CN114479256B - Low-melting-point high-melt-flow-rate carbon black master batch and preparation method thereof - Google Patents

Abstract

The invention discloses a carbon black masterbatch with low melting point and high melt flow rate. When the mass content of carbon black in the color masterbatch is as high as 40-50%, the mass melt flow rate (load 10.0kg, test temperature 190°C) is greater than 50g/10min, up to 800g/10min, can be easily mixed and dispersed with polyethylene and polypropylene resins during melt processing, especially at relatively low temperatures (110°C) with low melting point polyolefin resins including LDPE , EVA, POE, etc. mixed to meet its processing needs. The carbon black masterbatch with low melting point and high melt flow rate of the present invention is made of the following raw materials in mass ratio: 15-30 parts of polyethylene resin, 30-40 parts of liquid paraffin oil, 40-50 parts of carbon black, functional additives 0.05-0.1 part, antioxidant less than or equal to 0.01 part.

Description

A kind of carbon black master batch with low melting point and high melt flow rate and preparation method

technical field

The invention relates to a carbon black masterbatch and a preparation method, more specifically to a low melting point high melt flow rate carbon black masterbatch and a preparation method.

Background technique

Polyethylene is a semi-crystalline thermoplastic resin prepared by polymerization of ethylene as a monomer. It has certain rigidity, flexibility, odorless, non-toxic, good chemical stability, low water absorption and excellent electrical insulation. Polyethylene has many different classification methods according to the difference in polymerization method, molecular weight, chain structure and performance. At present, the more commonly used classification method is to classify according to the density of polyethylene resin, mainly including: high-density polyethylene (HDPE) , Medium Density Polyethylene (MDPE), Low Density Polyethylene (LDPE) and Linear Low Density Polyethylene (LLDPE). HDPE is the highest density among commercial polyethylenes, with a relative density of about 0.940-0.976g/cm ³ . At the same time, because of its most regular main chain structure and low branching degree, HDPE has the highest crystallinity and melting point. The crystallinity of HDPE is often as high as 80% to 90%, the melting point is about 135°C, and the maximum operating temperature can reach 100°C. HDPE's high density and high crystallinity make it superior to other polyethylene varieties in heat resistance, hardness, mechanical strength and creep properties, and is suitable for preparing engineering plastic parts for gas pipes, hot water pipes, automobiles and construction. The relative density of MDPE is 0.926-0.953g/cm ³ , which is slightly lower than that of HDPE. The crystallinity of MDPE is 70%-80%, and the melting temperature is 126-135°C. The remarkable feature of MDPE is resistance to environmental stress cracking and long-term retention of mechanical properties (such as strength, etc.), and it is often used in pipes, films, hollow containers, wire and cable coatings, etc. Compared with HDPE and MDPE, LDPE has lower crystallinity, density and melting point. This is because more side chains of different lengths are formed on the main molecular chain of the latter during the polymerization reaction, which reduces the crystallization ability. The crystallinity of LDPE is about 40%-50%, the density is 0.91-0.925g/cm ³ , and the melting point is 105-110°C. The low crystallinity of the LDPE structure improves the flexibility, extensibility, transparency, electrical insulation and processing properties of polyethylene, and can be used to prepare films, wires, cables, coatings, foamed plastics and other products, especially suitable for the preparation of soft, transparent, etc. plastic products.

LLDPE resin developed on the basis of traditional polyethylene resin is called third-generation polyethylene. LLDPE is a copolymer of ethylene and a small amount of α-olefin (such as 1-butene, 1-octene, etc.). Compared with LDPE resin, which has more branched chains of different lengths, the introduction of a small amount of comonomer makes the main chain structure of LLDPE resin only have very short branched chain structures. Although the density of LLDPE resin is almost similar to that of LDPE, it has higher crystallinity, softening temperature and melting temperature than LDPE. At the same time, LLDPE also has higher tensile strength, tear strength, environmental stress cracking resistance, low temperature resistance, A series of advantages such as heat resistance and puncture resistance. LLDPE has a wider range of applications, mainly including films, moldings, pipes, sheets, wires and cables, containers, fuel tanks and chemical tanks. Among the four commonly used polyethylene resin categories such as commercialized HDPE, MDPE, LDPE and LLDPE, LLDPE has the highest cost performance and the lowest market price. The density, crystallinity and melting point of polyethylene with different structures are compared in Table 1. The schematic diagram of the relationship between the melting temperature, crystallinity and crystal structure of the three polyethylene resins is shown in Figure 1.

Table 1 Comparison of density, crystallinity and melting point of polyethylene with different structures

performance HDPE MDPE LLDPE LDPE <![CDATA[Density, g/cm³]]> 0.940～0.976 0.926～0.953 0.918～0.935 0.910～0.925 Crystallinity, % 80～90 70～80 50～60 40～50 Melting point, °C 135 126～135 120～125 105～110

The advantage of using low-melting point polyethylene variety LDPE to prepare plastic products is that it has good toughness. It is often used to prepare transparent films, hoses, and foamed plastics. LDPE is more suitable for the preparation of chemically foamed and cross-linked foamed plastics. Polyethylene foam is a kind of wide source of raw materials, stable chemical properties, good cushioning and heat resistance, low thermal conductivity, density and water absorption, etc., especially the use of azodicarbonamide (AC) as the chemical The chemically cross-linked polyethylene foam prepared by the foaming agent and dicumyl peroxide (DCP) as the cross-linking agent also has the characteristics of good elasticity, high strength, and better cushioning performance. It is used in shock-absorbing and sealing parts for automobiles, It has more advantages in the application of sports shoes and individual combat equipment of field troops. Although LLDPE has many varieties, the highest cost performance, and the lowest commercial price in the commercial polyethylene resin category, it is not suitable for the preparation of chemically cross-linked polyethylene foam. This is because the melting point of LLDPE is relatively high, about 120-125 ° C. When LLDPE resin is mixed with auxiliary agents such as foaming agent AC and cross-linking agent DCP above this temperature, it is very easy to cause foaming agent AC and cross-linking agent DCP. Early decomposition interferes with and affects the later foaming process, making it difficult to prepare polyethylene foam with stable expansion ratio and performance. At the same time, the crystallinity of LLDPE resin is relatively higher than that of LDPE resin, and the foam plastic prepared by LLDPE has higher hardness, poor elasticity and hand feeling. Most of the commercialized chemically cross-linked polyethylene foams currently use LDPE as the base material or are prepared by blending LDPE with polymers with lower melting point and better elasticity, such as ethylene-vinyl acetate copolymer (EVA), EPDM, etc. rubber etc. EVA is a random copolymer formed of ethylene monomer and vinyl acetate (VAc) monomer. It has the characteristics of low melting point, good elasticity, and easy mixing with polyethylene. For example, the melting point of EVA resin with VAc mass content of 10-20wt% is 80 ~ 90 ℃, especially suitable for polyethylene foam with LDPE and chemical cross-linking method, and this modified foam has better elasticity and feel.

In the preparation of black chemically cross-linked LDPE or LDPE/EVA foam, the colorant needs to use pigment carbon black. When preparing foamed plastics, its volume will often expand by 2 to 30 times. At this time, in order to ensure the color requirements of the product, the amount of carbon black used is much larger than that of non-foamed polyethylene plastic products. At present, when producing black chemically cross-linked LDPE or LDPE/EVA foam plastics, most of the industry adopts two kinds of fractional coloring: ① directly using powdered carbon black for coloring, the advantage is low cost, but there are many disadvantages, for example: powdery carbon black is called It is easy to pollute the production equipment and the environment during the mixing process; as an inorganic material, carbon black with low apparent density and large specific surface area has low adhesion to the surface of polymer substrates such as LDPE and EVA, and it is difficult to pass the processing of common plastic products. The equipment directs it to disperse evenly. ②Using polyethylene as the carrier of carbon black masterbatch has the advantage of solving the problem of polluting production equipment and the environment during the weighing and mixing of powdered carbon black.

At present, commercialized polyolefin-based carbon black masterbatches are mostly made of HDPE and LLDPE as the matrix resin, and a small amount of LDPE and EVA are used as the matrix resin. This is because compared with LDPE and EVA, the high melt flow rate powdered LLDPE and HDPE suitable for the preparation of carbon black masterbatches are easy to get and the price is lower; the price of LDPE in the market is about 2000-3000 yuan/ton higher than that of LLDPE and HDPE , the price of general-purpose EVA is about 5,000-10,000 yuan/ton higher than that of LLDPE and HDPE, so there are fewer varieties and higher prices for high melt flow rate powdered LDPE and EVA resins suitable for preparing carbon black masterbatches. Based on the above analysis, it can be seen that the carbon black masterbatch prepared directly using HDPE or LLDPE as the matrix resin has a melting point of 120-135 ° C, which is not suitable for use as a colorant for chemically cross-linked LDPE or LDPE/EVA foam systems; Carbon black masterbatch made of LDPE or EVA as the matrix resin has a melting point of 85-110°C and is suitable for use as a colorant for chemically cross-linked LDPE or LDPE/EVA foam systems, but the cost of carbon black masterbatch is high. In addition, in the production process of black low-melting point flexible polyolefin films such as LDPE film, EVA film, polyolefin elastomer (POE) film, black LDPE, LDPE/EVA pipe, black low-smoke halogen-free polyolefin flame-retardant cable material, etc. Carbon black masterbatches with low melting point and high fluidity are also required. At present, due to the lack of supply and difficulty in procurement of powdered LDPE and EVA resins with high melt flow rates, the supply of low-cost, low-melting point, and high-melt flow rate carbon black masterbatches in the market is limited.

In summary, at present, in the preparation process of carbon black masterbatches with low melting point and high fluidity, especially low-cost, low-melting point, high-fluidity carbon black masterbatches with a wide range of raw materials, the products prepared by the prior art have certain advantages. limitations. Therefore, LLDPE resin, which has a wide range of raw materials and relatively low price, is designed as the base material, and liquid paraffin oil is used as the plasticizer in the amorphous region of LLDPE to further improve its fluidity while reducing the melting point and crystallinity of LLDPE. , low melting point, high carbon black content, high melt flow rate carbon black masterbatch, to meet the needs of low melting point polyolefins such as LDPE, EVA, POE and other related plastic product processing industries.

Contents of the invention

The purpose of the present invention is to solve the problems and deficiencies in the prior art, and to provide a carbon black masterbatch with a low melting point and a high melt flow rate. The present invention uses the polyethylene variety LLDPE with wide sources and low market price as the base resin to prepare Carbon black masterbatch with low cost, low melting point, high carbon black content, high melt flow rate. When the mass content of carbon black in the color masterbatch is as high as 40-50%, the mass melt flow rate (load 10.0kg, test temperature 190°C) is greater than 50g/10min, up to 800g/10min, and can be easily combined with polyethylene, poly Propylene resin is mixed and dispersed during melt processing, especially at a relatively low temperature (110°C) with low-melting polyolefin resins including LDPE, EVA, POE, etc. to meet its processing needs. Special materials, equipment selection, unique formula and process design also make the preparation of carbon black masterbatches maintain the characteristics of weak alkalinity and almost no antioxidant. The carbon black masterbatches of the present invention are especially suitable as chemical foaming and peroxide It is used as a coloring agent for preparing LDPE or LDPE/EVA foam plastic system, peroxide crosslinked polyolefin cable material, and low-smoke halogen-free flame-retardant cable material by cross-linking process.

The present invention also provides a method for preparing the carbon black masterbatch with a low melting point and a high melt flow rate. In the method, liquid paraffin oil, functional additives and antioxidants are added to a storage tank with stirring blades according to the formula ratio at room temperature A stable dispersion is formed in the medium; and then the mixture of LLDPE and paraffin oil containing additives is prepared by a twin-screw extruder, which can prevent carbon black from inhaling too much paraffin oil at the initial stage of mixing due to its strong ability to absorb paraffin oil, resulting in carbon black The melt flow rate of the masterbatch decreases and affects the melting point of LLDPE; finally, the LLDPE/paraffin oil mixture melt prepared above is mixed with the carbon black automatically measured by the weight loss scale in the weighing silo by means of a double-rotor continuous mixer. Mix, and further use a single-screw extruder to continue mixing evenly and obtain a low-melting-point high-melt flow rate carbon black masterbatch through a pelletizer underwater granulation process.

The present invention is achieved through the following technical solutions:

The carbon black masterbatch with low melting point and high melt flow rate of the present invention is made of the following raw materials in mass proportion:

The above-mentioned carbon black masterbatch with low melting point and high melt flow rate of the present invention, its further technical scheme is that described polyethylene resin is powdery linear low density polyethylene one or two kinds of different mass melt flow rate varieties combination. A still further technical solution is that the melt mass flow rate of the powdery linear low density polyethylene resin is 10-50 g/10 min under the conditions of a load of 2160 g and a test temperature of 190°C.

The above-mentioned carbon black masterbatch with low melting point and high melt flow rate of the present invention, its further technical solution can also be that the relative density of the liquid paraffin oil is 0.845-0.890g/cm ³ , and the kinematic viscosity at 100°C is 15-25mm ² /s, acid value ≤0.01mgKOH/g, initial boiling point above 350°C, low acid value and high viscosity varieties with average relative molecular weight ≥600.

The above-mentioned carbon black masterbatch with low melting point and high melt flow rate of the present invention, its further technical solution can also be that the average primary particle diameter of the carbon black is 20-30nm, the specific surface area is 50-70m ² /g, and the oil absorption value is 50 ～60mL/100g, tinting strength 120～130; the pH value of the carbon black aqueous dispersion obtained by mixing 50g carbon black and 100g boiling water is between 7～9 when cooled to 25°C. The carbon black has relatively high primary particle size and coloring strength, low specific surface area and oil absorption value, and weak alkalinity. Carbon black with this structural feature has a low ability to absorb liquid paraffin oil, and will not interfere with its plasticization of the amorphous region in linear low-density polyethylene resin due to a large amount of liquid paraffin oil absorption, which is beneficial to liquid paraffin oil. Play the role of lowering the melting point of linear low-density polyethylene; the weakly basic characteristics of carbon black can ensure that the carbon black masterbatch prepared by it is more suitable for peroxide crosslinked polyolefin products.

The further technical solution of the above-mentioned carbon black masterbatch with low melting point and high melt flow rate of the present invention can also be that the functional auxiliary agent is one of carbonate, nitrate or a combination thereof. The use of carbonates, nitrates, etc. can further reduce the oil absorption value of carbon black; especially carbonates can also effectively adjust the acidity and alkalinity of carbon black and liquid paraffin oil to make it show the weak alkalinity required by the formula. Carbonates are preferred as they are less corrosive to metal equipment. A further technical scheme is that the carbonate is one of potassium carbonate, sodium carbonate, sodium bicarbonate or a combination thereof.

The further technical solution of the above-mentioned carbon black masterbatch with low melting point and high melt flow rate of the present invention can also be that the antioxidant is one of the commercial antioxidants B215 and B225. The amount of antioxidant used here is very low, which is based on the fact that the carbon black masterbatch contains a large amount of liquid paraffin as a plasticizer in addition to using powdery linear low-density polyethylene with a relatively low melting point to further reduce the powdery linear low density. The melting point and processing temperature of density polyethylene, so the processing temperature of this carbon black masterbatch is lower than that of conventional carbon black masterbatch, and polyethylene is not easy to produce thermal degradation during processing; secondly, lower antioxidant usage The amount is also to ensure that the carbon black masterbatch is more suitable for peroxide crosslinked polyolefin products after the carbon black masterbatch is processed, and its products contain almost no antioxidants.

The preparation method of the above-mentioned low melting point high melt flow rate carbon black master batch of the present invention comprises the following steps:

Mixing of liquid paraffin oil and additives: Add liquid paraffin oil, functional additives, and antioxidants to a storage tank with stirring paddles at room temperature to form a stable dispersion. The liquid paraffin oil storage tank consists of two When working, the two storage tanks are used alternately. When one of them is used normally after stirring, the other is stirred and dispersed for standby;

Preparation of LLDPE/paraffin oil mixture by twin-screw extruder: first prepare LLDPE/paraffin oil mixture by using parallel twin-screw extruder, liquid paraffin oil is mixed with LLDPE resin through twin-screw extruder in proportion through metering pump, LLDPE powder The resin is added into the hopper by a dynamic weighing system (loss-in-weight automatic weighing scale), and the liquid paraffin oil is placed at one-third of the screw length near the hopper, and the temperature of the twin-screw extruder is controlled at 110-160°C; The process of feeding and mixing LLDPE, carbon black and paraffin oil at the same time is mainly to prevent carbon black from absorbing too much paraffin oil in the early stage of mixing due to its strong ability to absorb paraffin oil, resulting in a decrease in the melt flow rate of the carbon black masterbatch and Affect the melting point drop of LLDPE;

Preparation of carbon black masterbatch: ① Double-rotor continuous mixer blending: the LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous Blending in the kneader, the speed of the twin-rotor continuous kneader is controlled at 500-550rpm, and the temperature of the kneader is 120-160°C; ②Single-screw extruder granulation: LLDPE/paraffin The oil/carbon black mixing system is further mixed evenly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater granulation process of the pelletizer; the screw speed of the single-screw extruder is 70-80rpm , The temperature of the conveying section of the machine is controlled at 80-100°C, and the temperature of the plasticizing section and the machine head is controlled at 100-150°C.

Compared with the prior art, the present invention has the following beneficial effects:

本发明抗氧剂的使用量很低，是基于该炭黑母粒配方中使用大量液体石蜡作为增塑剂进一步较低粉状线型低密度聚乙烯的熔点和加工温度，因此该炭黑母粒的加工温度低于常规炭黑母粒的加工温度，聚乙烯在加工过程中不容易产生热降解；其次，由于抗氧剂的存在会消耗过氧化物交联剂分解产生的部分自由基降低交联效率，因此配方设计中较低的抗氧剂使用量也是为了炭黑母粒加工完成以后其产品中几乎不含抗氧剂，可以保证制得的炭黑母粒更适用于过氧化物交联的聚烯烃制品。

将液体石蜡油、功能助剂、抗氧剂于室温下按照配方比例加入带有搅拌桨叶的储罐中形成稳定的分散液有助于少量功能助剂和抗氧剂的分散。采用平行双螺杆挤出机首先制备LLDPE/石蜡油混合物再与炭黑混合制备母粒，不采用LLDPE、炭黑和石蜡油三者同时投料混合的工艺，主要是为了避免炭黑因较强的吸收石蜡油能力而在混合初期过多吸入石蜡油，导致炭黑母粒熔体流动速率下降和影响LLDPE的熔点下降幅度。The present invention overcomes the following deficiencies that mainly exist in the preparation of carbon black masterbatches in the prior art, and performs targeted formulation and process design and creative improvements: ① most of the existing carbon black masterbatches made of polyethylene as a carrier are in powder form LLDPE and HDPE are used as matrix resins, but LDPE and EVA resins are rarely used. This is because compared with LDPE and EVA, the high melt flow rate powdered LLDPE and HDPE suitable for the preparation of carbon black masterbatches are easy to get and the price is lower; the price of LDPE in the market is about 2000-3000 yuan/ton higher than that of LLDPE and HDPE , the price of general-purpose EVA is about 5,000-10,000 yuan/ton higher than that of LLDPE and HDPE, so there are fewer varieties and higher prices for high melt flow rate powdered LDPE and EVA resins suitable for preparing carbon black masterbatches. ② Differential scanning calorimetry (DSC) was used to test the melting temperatures of different polyolefin resins at a heating rate of 10°C/min: HDPE 135°C, LLDPE 125°C, LDPE 110°C, and EVA (VAc 14wt% ) at 90°C, theoretically, it is the best choice to use LDPE and EVA resin as the carrier to prepare low melting point carbon black masterbatch, but due to the lack of supply, high price and purchase of powdered LDPE and EVA resin with high melt flow rate in the market Difficulties limit the supply and demand of low-cost, low-melting point, high-melt flow rate carbon black masterbatches in the market. ③At present, when azodicarbonamide (AC) is used as a chemical foaming agent and dicumyl peroxide (DCP) is used as a crosslinking agent to prepare polyolefin foam plastics, most polyolefins use LDPE, EVA or LDPE/EVA as the main raw material. This is because the melting points of LDPE and EVA are relatively low. When the temperature is controlled near the melting point of LDPE at 110°C, when LDPE and EVA are mixed with foaming agent AC and crosslinking agent DCP, they will not be damaged due to the early decomposition of foaming agent AC and crosslinking agent DCP. Affect the later foaming process. Therefore, when preparing black polyolefin foam plastics, it is not suitable to use LLDPE or HDPE as the base material to mix carbon black masterbatch with carbon black, because this kind of carbon black masterbatch needs to be heated at 125-135°C In order to mix evenly with LDPE and EVA, such a high temperature will cause the early decomposition of the blowing agent AC and the crosslinking agent DCP, which will affect the processing stability of the later foam plastics. ④Although the melting point of LLDPE resin is about 125°C, which is about 15°C higher than that of LDPE, it is not suitable to directly use it as a matrix material to prepare carbon black masterbatches with low melting point. However, we creatively proposed to use LLDPE resin, which is easy to get in the market and relatively low in cost, as the matrix, and use liquid paraffin oil with specific properties as the plasticizer, and use the plasticizing effect of liquid paraffin oil on the LLDPE amorphous region to reduce its crystallinity. Its melting point drops, realizing the feasibility of using LLDPE resin with higher melting point to prepare low melting point carbon black masterbatch. ⑤Because the relative density (0.845～0.890g/cm ³ ) and molecular weight of liquid paraffin oil are lower than those of LLDPE, and its price is lower than that of LLDPE resin, even lower than that of LDPE resin, so LLDPE and a certain proportion of liquid paraffin In addition to the characteristics of lower melting point, the carbon black masterbatch made by mixing oil as the main material and carbon black has lower raw material formula cost, lower density of the prepared carbon black masterbatch, better fluidity and more market competitiveness . ⑥In our research, we found that when the amount of liquid paraffin oil is not too large, the melting point of LLDPE cannot be effectively reduced. For example, the mass ratio LLDPE/liquid paraffin oil=100/0～100/20, and the melting point of LLDPE only drops from 125°C to 120°C , a small decrease. If the melting point of LLDPE in the LLDPE/liquid paraffin oil mixture is to be reduced from 125° C. to 110° C. or even lower than the melting point of LDPE, the mass ratio of LLDPE/liquid paraffin oil must reach 100/100, or even higher such as 100/250. ⑦ Although the melting point of LLDPE can be lowered by mixing LLDPE with a certain proportion of liquid paraffin oil, this mixture has no practical application value because the mixture (100/20) containing a small amount of liquid paraffin oil will crystallize due to LLDPE when cooled to room temperature. And its extruded precipitation surface, the LLDPE precipitation phenomenon of high proportion paraffin oil content (100/100～100/250) among the present invention is more obvious, affects the use of finished product. We cleverly used the porosity and high oil absorption characteristics of carbon black to avoid the precipitation of liquid paraffin oil while using a high proportion of liquid paraffin oil and LLDPE to prepare low-melting point carbon black masterbatches. ⑧The present invention screens out through research that the suitable liquid paraffin oil is low acid value (≤0.01mgKOH/g), high viscosity (kinematic viscosity at 100°C is 15-25mm ² /s), which is based on the high proportion of liquid paraffin oil High-viscosity varieties have less volatility and migration when oils are processed at high temperatures. In addition, since acidic substances will cause ionic decomposition of peroxide crosslinking agents, thereby reducing the efficiency of free radical decomposition, the low acid value index of liquid paraffin oil can ensure that the carbon black masterbatch prepared by it is more suitable for peroxide Cross-linked polyolefin articles. 9. Another feature of the present invention is that the type selection of carbon black is different from the conventional masterbatch formula design and is uniquely innovative. Most of the carbon black in the masterbatch of the prior art is selected with a small primary particle size (15～20nm) and a large specific surface area ( 100～120m ² /g), high oil absorption value (105～125mL/100g), in order to meet the requirements of easy dispersion and good coloring effect in the later use of the masterbatch. Varieties with small primary particle size, large specific surface area, and high oil absorption value are more likely to absorb liquid paraffin oil. In order to avoid competition between carbon black and the amorphous region in LLDPE resin to absorb paraffin oil, it is proposed to use relatively high primary particle size ( 20-30nm), lower specific surface area (50-70m ² /g) and oil absorption value (50-60mL/100g) carbon black varieties, carbon black with this structural feature has a lower ability to absorb liquid paraffin oil, It will not interfere with its plasticizing effect on the amorphous region in the linear low-density polyethylene resin due to a large amount of liquid paraffin oil absorbed, and is conducive to the role of the liquid paraffin oil in lowering the melting point of the linear low-density polyethylene. In addition, carbon black varieties are required to meet both high coloring strength and weak alkaline characteristics. The weak alkaline characteristics of carbon black are also to ensure that the carbon black masterbatch prepared by it is more suitable for peroxide crosslinked polyolefin products. ⑩Although commercially available carbon black has a lower specific surface area (≤20m ² /g), its ability to absorb liquid paraffin oil is weak, but the disadvantage of this type of carbon black is that its primary particle size is too large ( 100-500nm), the coloring effect is reduced. In order to ensure that the primary particle size (20-30nm) carbon black we choose has a good coloring effect, and at the same time further reduce the specific surface area of carbon black and reduce the competitive absorption of liquid paraffin oil, carbonic acid is added to the formula system. The salt method further reduces the oil absorption value of carbon black, and at the same time uses carbonate to effectively adjust the acidity and alkalinity of carbon black and liquid paraffin oil, and finally makes the prepared carbon black masterbatch weakly alkaline. Additionally, carbonates are less corrosive to metal equipment.

The usage amount of antioxidant of the present invention is very low, is to use a large amount of liquid paraffins as plasticizer further lower melting point and processing temperature of powdery linear low density polyethylene based on this carbon black masterbatch formula, so this carbon black masterbatch The processing temperature of the pellets is lower than that of conventional carbon black masterbatches, and polyethylene is not prone to thermal degradation during processing; secondly, due to the presence of antioxidants, it will consume part of the free radicals generated by the decomposition of peroxide crosslinking agents to reduce Cross-linking efficiency, so the lower amount of antioxidant used in the formulation design is also for the fact that after the carbon black masterbatch is processed, the product hardly contains antioxidants, which can ensure that the prepared carbon black masterbatch is more suitable for peroxide Cross-linked polyolefin articles.

Add liquid paraffin oil, functional additives, and antioxidants into a storage tank with stirring blades according to the formula ratio at room temperature to form a stable dispersion, which helps to disperse a small amount of functional additives and antioxidants. The parallel twin-screw extruder is used to first prepare the LLDPE/paraffin oil mixture and then mix it with carbon black to prepare the masterbatch. The process of feeding and mixing LLDPE, carbon black and paraffin oil at the same time is not used, mainly to avoid carbon black due to strong The ability to absorb paraffin oil and excessive inhalation of paraffin oil at the initial stage of mixing will lead to a decrease in the melt flow rate of the carbon black masterbatch and affect the melting point of LLDPE.

In summary, low melting point of the present invention, high melt flow rate carbon black master batch, its carbon black content is up to 40～50%, under load 10.0kg, test temperature 190 ℃ (polyethylene is the carbon black master batch of carrier Usually the test load is 21.6kg, the temperature is 190°C) the melt mass flow rate is greater than 50g/10min, the highest is even greater than 800g/10min, the DSC test (heating rate 10°C/10min) the melting temperature is less than or equal to 110°C, which enriches the current market. Provides varieties of general-purpose carbon black masterbatches, providing users with more choices. When the carbon black masterbatch can be used in the processing of low-melting point polyolefin plastic products, it also has a series of advantages such as relatively low processing temperature, high coloring strength, and good dispersibility. In addition, the main material of the carbon black masterbatch is composed of LLDPE and paraffin oil, the cost is relatively low, and the preparation process is simple. The carbon black master batch with low melting point and high melt flow rate of the present invention is mainly suitable for polymer systems such as LDPE, EVA and POE, and also suitable for high melting point polymer systems such as LLDPE, HDPE and PP.

Description of drawings

Fig. 1 is a schematic diagram of the relationship between melting temperature, crystallinity and crystal structure of three kinds of polyethylene resins.

Fig. 2 Schematic diagram of the effect of liquid paraffin oil content on the melting temperature, crystallinity and crystal structure of LLDPE resin.

Figure 3-1, Figure 3-2 Schematic diagram of the effect of adding liquid paraffin oil on the microstructure and performance of carbon black masterbatch.

Figure 4 Schematic diagram of the production process of low melting point, high melt flow rate carbon black masterbatch.

Fig. 5 (a), Fig. 5 (b) DSC test part embodiment, the heating curve and the melting temperature of the sample of the comparative example.

Detailed ways

The present invention is illustrated below through specific examples, but the present invention is not limited to these examples.

Example 1

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, temperature MFR=30g/10min at 190°C) 10, LLDPE resin (load 2160g, temperature 190°C when MFR=50g/10min) 20, liquid paraffin oil (100 Kinematic viscosity at ℃ is 15mm ² /s) 30, carbon black (primary particle size 20nm, specific surface area 70m ² /g, oil absorption 60mL/100g, coloring strength 120, pH value 7) 40, antioxidant B215 0.01, Potassium carbonate 0.05.

Preparation process: 1. Mixing of liquid paraffin oil and additives: add liquid paraffin oil, functional additives, and antioxidants into a storage tank with stirring blades according to the formula ratio at room temperature to form a stable dispersion for later use. 2. Twin-screw extruder prepares LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the twin-screw extruder through a metering pump, and LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale. The temperature of the screw extruder is controlled at 120-160°C. 3. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 500 rpm, and the temperature of the mixer is 120-150°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 70rpm, the temperature of the conveying section of the extruder is controlled at 80°C, and the temperature of the plasticizing section and the head is controlled at 100-140°C.

The properties of low melting point and high melt flow rate carbon black masterbatch are shown in Table 1 after testing.

Example 2

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, temperature MFR=50g/10min at 190°C) 20, LLDPE resin (load 2160g, temperature 190°C when MFR=10g/10min) 5 liquid paraffin oil (100°C Kinematic viscosity under the conditions is 25mm ² /s) 35, carbon black (primary particle size 25nm, specific surface area 60m ² /g, oil absorption value 50mL/100g, coloring strength 120, pH value 7.5) 40, antioxidant B225 0.008, carbonic acid Sodium 0.1.

Preparation process: 1. Mixing of liquid paraffin oil and additives: add liquid paraffin oil, functional additives, and antioxidants into a storage tank with stirring blades according to the formula ratio at room temperature to form a stable dispersion for later use. 2. Twin-screw extruder prepares LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the twin-screw extruder through a metering pump, and LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale. The temperature of the screw extruder is controlled at 120-160°C. 3. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 500 rpm, and the temperature of the mixer is 120-150°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 80rpm, the temperature of the conveying section of the extruder is controlled at 90°C, and the temperature of the plasticizing section and the head is controlled at 100-140°C.

The properties of low melting point and high melt flow rate carbon black masterbatch are shown in Table 1 after testing.

Example 3

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=48g/10min at 190°C) 20, liquid paraffin oil (kinematic viscosity 20mm ² /s at 100°C) 40, carbon black (primary particle Diameter 25nm, specific surface area 50m ² /g, oil absorption 55mL/100g, coloring strength 125, pH 9)40, antioxidant B215 0.01, sodium bicarbonate 0.08.

Preparation process: 1. Mixing of liquid paraffin oil and additives: add liquid paraffin oil, functional additives, and antioxidants into a storage tank with stirring blades according to the formula ratio at room temperature to form a stable dispersion for later use. 2. Twin-screw extruder prepares LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the twin-screw extruder through a metering pump, and LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale. The temperature of the screw extruder is controlled at 110-150°C. 3. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 500 rpm, and the temperature of the mixer is 130-160°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 75rpm, the temperature of the conveying section of the extruder is controlled at 100°C, and the temperature of the plasticizing section and the head is controlled at 110-150°C.

The properties of low melting point and high melt flow rate carbon black masterbatch are shown in Table 1 after testing.

Example 4

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=25g/10min at 190°C) 20, liquid paraffin oil (kinematic viscosity 15mm ² /s at 100°C) 35, carbon black (primary grain Diameter 20nm, specific surface area 55m ² /g, oil absorption value 55mL/100g, coloring strength 130, pH value 8)45, antioxidant B215 0.01, potassium carbonate 0.05, sodium carbonate 0.05.

Preparation process: 1. Mixing of liquid paraffin oil and additives: add liquid paraffin oil, functional additives, and antioxidants into a storage tank with stirring blades according to the formula ratio at room temperature to form a stable dispersion for later use. 2. Twin-screw extruder prepares LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the twin-screw extruder through a metering pump, and LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale. The temperature of the screw extruder is controlled at 120-160°C. 3. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 550rpm, and the temperature of the mixer is 120-150°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 75rpm, the temperature of the conveying section of the extruder is controlled at 90°C, and the temperature of the plasticizing section and the head is controlled at 100-140°C.

The properties of low melting point and high melt flow rate carbon black masterbatch are shown in Table 1 after testing.

Example 5

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=35g/10min at 190°C) 15, liquid paraffin oil (kinematic viscosity 20mm ² /s at 100°C) 35, carbon black (primary particle Diameter 20nm, specific surface area 65m ² /g, oil absorption 55mL/100g, coloring strength 120, pH 8.5)50, antioxidant B215 0.005, potassium carbonate 0.02, sodium carbonate 0.03, sodium bicarbonate 0.05.

Preparation process: 1. Mixing of liquid paraffin oil and additives: add liquid paraffin oil, functional additives, and antioxidants into a storage tank with stirring blades according to the formula ratio at room temperature to form a stable dispersion for later use. 2. Twin-screw extruder prepares LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the twin-screw extruder through a metering pump, and LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale. The temperature of the screw extruder is controlled at 110-150°C. 3. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 550 rpm, and the temperature of the mixer is 130-160°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 80rpm, the temperature of the conveying section of the extruder is controlled at 100°C, and the temperature of the plasticizing section and the head is controlled at 110-150°C.

The properties of low melting point and high melt flow rate carbon black masterbatch are shown in Table 1 after testing.

Example 6

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=50g/10min at 190°C) 15, liquid paraffin oil (kinematic viscosity 15mm ² /s at 100°C) 35, carbon black (primary particle Diameter 25nm, specific surface area 50m ² /g, oil absorption 50mL/100g, coloring strength 125, pH 7)50, antioxidant B225 0.01, sodium bicarbonate 0.05.

Preparation process: 1. Mixing of liquid paraffin oil and additives: add liquid paraffin oil, functional additives, and antioxidants into a storage tank with stirring blades according to the formula ratio at room temperature to form a stable dispersion for later use. 2. Twin-screw extruder prepares LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the twin-screw extruder through a metering pump, and LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale. The temperature of the screw extruder is controlled at 110-150°C. 3. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 550 rpm, and the temperature of the mixer is 130-160°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 80rpm, the temperature of the conveying section of the extruder is controlled at 95°C, and the temperature of the plasticizing section and the head is controlled at 110-150°C.

The properties of low melting point and high melt flow rate carbon black masterbatch are shown in Table 1 after testing.

Example 7

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=10g/10min at 190°C) 15, liquid paraffin oil (kinematic viscosity 20mm ² /s at 100°C) 35, carbon black (primary grain Diameter 25nm, specific surface area 70m ² /g, oil absorption 60mL/100g, tinting strength 130, pH 8)50, antioxidant B225 0.01, potassium carbonate 0.1.

Preparation process: 1. Mixing of liquid paraffin oil and additives: add liquid paraffin oil, functional additives, and antioxidants into a storage tank with stirring blades according to the formula ratio at room temperature to form a stable dispersion for later use. 2. Twin-screw extruder prepares LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the twin-screw extruder through a metering pump, and LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale. The temperature of the screw extruder is controlled at 110-150°C. 3. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 550 rpm, and the temperature of the mixer is 130-160°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 80rpm, the temperature of the conveying section of the extruder is controlled at 100°C, and the temperature of the plasticizing section and the head is controlled at 110-150°C.

The properties of low melting point and high melt flow rate carbon black masterbatch are shown in Table 1 after testing.

Example 8

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, temperature MFR=16g/10min at 190°C) 5, LLDPE resin (load 2160g, temperature 190°C when MFR=25g/10min) 10, liquid paraffin oil (100 The kinematic viscosity at ℃ is 25mm ² /s) 35, carbon black (primary particle size 25nm, specific surface area 60m ² /g, oil absorption 55mL/100g, coloring strength 125, pH value 9) 50, antioxidant B225 0.01, Sodium carbonate 0.08.

Preparation process: 1. Mixing of liquid paraffin oil and additives: add liquid paraffin oil, functional additives, and antioxidants into a storage tank with stirring blades according to the formula ratio at room temperature to form a stable dispersion for later use. 2. Twin-screw extruder prepares LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the twin-screw extruder through a metering pump, and LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale. The temperature of the screw extruder is controlled at 110-150°C. 3. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 550 rpm, and the temperature of the mixer is 130-160°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 80rpm, the temperature of the conveying section of the extruder is controlled at 90°C, and the temperature of the plasticizing section and the head is controlled at 110-150°C.

The properties of low melting point and high melt flow rate carbon black masterbatch are shown in Table 1 after testing.

Comparative example 1

Raw material formulation (mass ratio, parts): LDPE resin (MFR=1.5g/10min at load 2160g, temperature 190°C) 100. The properties of the resin are shown in Table 2 after testing.

Comparative example 2

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=2g/10min at a temperature of 190°C) 100. The properties of the resin are shown in Table 2 after testing.

Comparative example 3

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=50g/10min at temperature 190°C) 60, high structure carbon black (particle size 20nm, specific surface area 120m ² /g, oil absorption value 115mL/100g, Tinting strength 105)40.

Preparation process: ① Double-rotor continuous mixer blending: the integrated feeding system is turned on to transport LLEPE and high-structure carbon black to the intermediate silo of the dynamic weighing system, and then the weight loss scale in the weighing silo is automatically weighed and then continuously Continuously and directly put into the twin-rotor continuous mixer for blending, wherein the speed of the twin-rotor continuous mixer is controlled at 500rpm, and the temperature of the mixer is 150-180°C. ②Single-screw extruder granulation: the blended material in the twin-rotor continuous mixer is finally subjected to the underwater granulation process of the pelletizer to obtain carbon black masterbatch. Among them, the screw speed of the single-screw extruder is 80rpm, the temperature of the conveying section is controlled at 100°C, and the temperature of the plasticizing section and the head is controlled at 160-190°C. The properties of the carbon black masterbatch are shown in Table 2 after testing.

Comparative example 4

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=2g/10min at 190°C) 100, liquid paraffin oil (kinematic viscosity 25mm ² /s at 100°C) 20.

Preparation process: The liquid paraffin oil is mixed with the LLDPE resin in proportion to the twin-screw extruder from the storage tank through the metering pump, and the LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale, and the temperature of the twin-screw extruder is controlled at 110 ~150°C, cooled and pelletized to obtain LLDPE/paraffin oil blend. The performance of the LLDPE/paraffin oil blend is shown in Table 2 after testing.

Comparative example 5

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=25g/10min at 190°C) 50, liquid paraffin oil (kinematic viscosity 25mm ² /s at 100°C) 10, high-structure carbon black (Particle size 20nm, specific surface area 120m ² /g, oil absorption value 115mL/100g, coloring strength 105) 40, antioxidant B225 0.2.

Preparation process: 1. Twin-screw extruder to prepare LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the storage tank through a metering pump, and the LLDPE powder resin is mixed with a weight-loss automatic weighing scale Add in the hopper, and control the temperature of the twin-screw extruder at 120-160°C. 2. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 550 rpm, and the temperature of the mixer is 130-160°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 80rpm, the temperature of the conveying section of the extruder is controlled at 100°C, and the temperature of the plasticizing section and the head is controlled at 120-160°C.

The properties of the carbon black masterbatch are shown in Table 2 after testing.

Comparative example 6

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=2g/10min at 190°C) 100, liquid paraffin oil (kinematic viscosity 25mm ² /s at 100°C) 50.

Preparation process: The liquid paraffin oil is mixed with the LLDPE resin in proportion to the twin-screw extruder from the storage tank through the metering pump, and the LLDPE powdery resin is added into the hopper with a weight-loss automatic weighing scale, and the temperature of the twin-screw extruder is controlled at 110 ~150°C, cooled and pelletized to obtain LLDPE/paraffin oil blend. The performance of the LLDPE/paraffin oil blend is shown in Table 2 after testing.

Comparative example 7

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=20g/10min at 190°C) 50, liquid paraffin oil (kinematic viscosity 25mm ² /s at 100°C) 10, high-structure carbon black (Particle size 20nm, specific surface area 120m ² /g, oil absorption value 115mL/100g, coloring strength 105) 40, antioxidant B225 0.2.

Preparation process: 1. Twin-screw extruder to prepare LLDPE/paraffin oil mixture: liquid paraffin oil is mixed with LLDPE resin in proportion through the storage tank through a metering pump, and the LLDPE powder resin is mixed with a weight-loss automatic weighing scale Add in the hopper, and control the temperature of the twin-screw extruder at 110-150°C. 2. Preparation of carbon black masterbatch: The LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous mixer for blending with the carbon black automatically measured by the weight loss scale in the weighing silo. The speed of the twin-rotor continuous mixer is controlled at 550 rpm, and the temperature of the mixer is 130-160°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 80rpm, the temperature of the conveying section of the extruder is controlled at 90°C, and the temperature of the plasticizing section and the head is controlled at 110-150°C.

The properties of the carbon black masterbatch are shown in Table 2 after testing.

Comparative example 8

Raw material formula (mass ratio, parts): LLDPE resin (load 2160g, MFR=50g/10min at 190°C) 40, liquid paraffin oil (kinematic viscosity 25mm ² /s at 100°C) 20, high-structure carbon black (Particle size 20nm, specific surface area 120m ² /g, oil absorption value 115mL/100g, coloring strength 105) 40, antioxidant B225 0.01.

Preparation process: 1. Mixed absorption of liquid paraffin oil, carbon black, and antioxidant: Utilizing high-structure carbon black which has a strong ability to absorb liquid paraffin oil, firstly liquid paraffin oil, antioxidant, and carbon black are mixed at room temperature Mix evenly according to the formula ratio to form a carbon black mixture that absorbs paraffin oil. 2. Preparation of carbon black masterbatch: the above-mentioned carbon black mixture absorbing paraffin oil and LLDPE resin are continuously and directly put into the double-rotor continuous mixer for blending after being automatically measured by the loss-in-weight scale in the weighing silo. The speed of the continuous mixer is controlled at 550 rpm, and the temperature of the mixer is 130-160°C. The LLDPE/paraffin oil/carbon black mixing system in the twin-rotor continuous mixer is further mixed uniformly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater pelletizing process of the pelletizer. The screw speed of the screw extruder is 80rpm, the temperature of the conveying section of the extruder is controlled at 90°C, and the temperature of the plasticizing section and the head is controlled at 110-150°C. The properties of the carbon black masterbatch are shown in Table 2 after testing.

Table 1 Example 1～Example 8 formula and performance list

*The mass content of carbon black is tested according to the international standard ISO 6964; **The melt mass flow rate of carbon black masterbatch is tested according to the international standard ISO 1133, with a load of 10kg and a temperature of 190°C; ***The melting point is tested by a differential scanning calorimeter, The heating rate is 10°C/min, and the peak temperature on the second heating curve after canceling the heat removal history; ****The carbon black particle dispersion size grade and dispersion apparent grade are tested in accordance with the international standard ISO 18553. The test resin is LDPE, carbon black Black mass content 2%.

Table 2 List of formulations and properties of Comparative Example 1 to Comparative Example 8

*The mass content of carbon black is tested according to the international standard ISO 6964; **The melt mass flow rate of carbon black masterbatch is tested according to the international standard ISO 1133, with a load of 10kg and a temperature of 190°C; ***The melting point is tested by a differential scanning calorimeter, The heating rate is 10°C/min, and the peak temperature on the second heating curve after canceling the heat removal history; ****The carbon black particle dispersion size grade and dispersion apparent grade are tested in accordance with the international standard ISO 18553. The test resin is LDPE, carbon black Black mass content 2%.

Claims (6)

1. a low melting point high melt flow rate carbon black masterbatch, is characterized in that, is made of the raw material of following mass proportioning: 15-30 parts of polyethylene resin, 30-40 parts of liquid paraffin oil, 40-50 parts of carbon black, 0.05-0.1 part of functional auxiliary agent, and less than or equal to 0.01 part of antioxidant; wherein, the polyethylene resin is powder A combination of one or two varieties of linear low-density polyethylene with different mass melt flow rates; the liquid paraffin oil has a relative density of 0.845-0.890 g/cm ³ and a kinematic viscosity of 15-25 mm ² at 100°C /s, acid value ≤0.01mgKOH/g, initial boiling point above 350°C, low acid value and high viscosity varieties with average relative molecular mass ≥600; the carbon black has an average primary particle size of 20-30 nm and a specific surface area of 50 ~70 m ² /g, oil absorption value 50~60 mL/100g, tinting strength 120~130; the carbon black water dispersion obtained by mixing 50g carbon black and 100g boiling water has a pH value between 7~9 when cooled to 25°C ; The preparation method of described low melting point high melt flow rate carbon black masterbatch, comprises the following steps: Mixing of liquid paraffin oil and additives: Add liquid paraffin oil, functional additives, and antioxidants to a storage tank with stirring paddles at room temperature to form a stable dispersion. The liquid paraffin oil storage tank consists of two When working, the two storage tanks are used alternately. When one of them is used normally after stirring, the other is stirred and dispersed for standby; Preparation of LLDPE/paraffin oil mixture by twin-screw extruder: first prepare LLDPE/paraffin oil mixture by using parallel twin-screw extruder, liquid paraffin oil is mixed with LLDPE resin through twin-screw extruder in proportion through metering pump, LLDPE powder The resin is added into the hopper using a dynamic weighing system, that is, a loss-in-weight automatic weighing scale. Liquid paraffin oil is placed at a third of the screw length near the hopper, and the temperature of the twin-screw extruder is controlled at 110~160°C; Preparation of carbon black masterbatch: ① Double-rotor continuous mixer blending: the LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous Blending in the kneader, the speed of the twin-rotor continuous kneader is controlled at 500~550rpm, and the temperature of the kneader is 120~160°C; ②Single-screw extruder granulation: LLDPE/paraffin The oil/carbon black mixing system is further mixed evenly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater granulation process of the pelletizer; the screw speed of the single-screw extruder is 70~80 rpm, the temperature of the conveying section of the machine is controlled at 80~100°C, and the temperature of the plasticizing section and machine head is controlled at 100~150°C. 2. The carbon black masterbatch with low melting point and high melt flow rate according to claim 1, characterized in that, the powdery linear low density polyethylene resin melts under the conditions of 2160g and 190°C of test temperature under the condition of load of 2160g and test temperature. The body mass flow rate is 10~50g/10min. 3. The carbon black masterbatch with low melting point and high melt flow rate according to claim 1, characterized in that, the functional auxiliary agent is one of carbonate, nitrate or a combination thereof. 4. The carbon black masterbatch with low melting point and high melt flow rate according to claim 3, characterized in that, the carbonate is one of potassium carbonate, sodium carbonate, sodium bicarbonate or a combination thereof. 5. The carbon black masterbatch with low melting point and high melt flow rate according to claim 1, characterized in that, the antioxidant is one of the commercial antioxidants B215 and B225. 6. a preparation method of the low melting point high melt flow rate carbon black masterbatch as described in any one of claim 1-5, is characterized in that, comprises the following steps: Mixing of liquid paraffin oil and additives: Add liquid paraffin oil, functional additives, and antioxidants to a storage tank with stirring paddles at room temperature to form a stable dispersion. The liquid paraffin oil storage tank consists of two When working, the two storage tanks are used alternately. When one of them is used normally after stirring, the other is stirred and dispersed for standby; Preparation of LLDPE/paraffin oil mixture by twin-screw extruder: first prepare LLDPE/paraffin oil mixture by using parallel twin-screw extruder, liquid paraffin oil is mixed with LLDPE resin through twin-screw extruder in proportion through metering pump, LLDPE powder The resin is added into the hopper using a dynamic weighing system, that is, a loss-in-weight automatic weighing scale. Liquid paraffin oil is placed at a third of the screw length near the hopper, and the temperature of the twin-screw extruder is controlled at 110~160°C; Preparation of carbon black masterbatch: ① Double-rotor continuous mixer blending: the LLDPE/paraffin oil mixture melt prepared above is continuously and directly put into the double-rotor continuous Blending in the kneader, the speed of the twin-rotor continuous kneader is controlled at 500~550rpm, and the temperature of the kneader is 120~160°C; ②Single-screw extruder granulation: LLDPE/paraffin The oil/carbon black mixing system is further mixed evenly in the single-screw extruder, and finally the carbon black masterbatch with low melting point and high melt flow rate is obtained through the underwater granulation process of the pelletizer; the screw speed of the single-screw extruder is 70~80 rpm, the temperature of the conveying section of the machine is controlled at 80~100°C, and the temperature of the plasticizing section and machine head is controlled at 100~150°C.

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