CN107189345A - A kind of graphene/organic fiber In-sltu reinforcement urea-formaldehyde foam material and preparation method thereof - Google Patents

Abstract

The invention discloses a graphene/organic fiber in-situ reinforced urea-formaldehyde foam material and a preparation method thereof. Ultrasonic dispersion at ℃ for 0.5~2h, then adjust the pH value of the system to 7.8~8.5, add the first batch of urea, react at 70~85℃ for 0.5~2h, immediately adjust the pH value of the system to 4.5~5.2 with formic acid solution, continue When the reaction system appears to be atomized, add the second batch of urea and adjust the pH of the system to 7-9 after 0.5-2 hours of reaction, add the third batch of urea, react for 5-30 minutes and then cut the material to obtain graphene-modified UF Resin solution; add 0.05-20 parts of organic fiber and 1-10 parts of surfactant to the resin solution, stir at high speed for 1-5 minutes, add 1-10 parts of foaming agent, continue stirring for 1-10 minutes, add 0.01-5 parts The curing agent is stirred evenly and poured into a foaming mold, and foamed and cured in a hot oven at 30-120°C to obtain a graphene/organic fiber in-situ reinforced urea-formaldehyde foam material.

Description

A kind of graphene/organic fiber in-situ reinforced urea-formaldehyde foam material and preparation method thereof

1. Technical field

The invention relates to a graphene/organic fiber in-situ reinforced urea-formaldehyde foam material and a preparation method thereof, belonging to the field of polymer material synthesis and processing.

2. Background technology

Foam plastics can be used for thermal insulation, sound absorption and sound insulation, packaging shock absorption, dust prevention, explosion suppression, etc., and the market is huge. At present, the commonly used foam plastics are mostly polystyrene (PS), polypropylene (PP) or polyurethane (PU) foam. Toxic fumes pose a serious safety hazard.

Urea-formaldehyde (UF) foam is a kind of amino foam obtained by foaming and curing the resin obtained by polycondensation reaction of urea and formaldehyde. The UF combustion process can produce inert gases such as NH ₃ , CO ₂ , H ₂ O, and at the same time form a carbonized layer on the surface of the material to prevent the flame from spreading further. The combustion aid can reach the flame-retardant level, and its all-water-based foaming process is environmentally friendly, simple, and easy to implement. Therefore, compared with traditional foam materials such as PS and PU foam, UF foam is not only cheap, but also has high temperature resistance, excellent flame retardancy (flammability), low smoke density, no molten droplets and no toxic gas generation during combustion Small and other advantages. However, there are very few commercial products and applications of UF foam on the market. This is mainly due to the lack of flexible groups in the UF molecular chain, resulting in high brittleness, easy cracking, slag drop, and low mechanical strength of the foam products.

At present, the research reports related to UF foam enhancement and toughening modification mainly include: CN201310259583.5 uses lignin to modify UF foam, and the modified foam has lower formaldehyde emission and better toughness; CN201310236803.2 uses methylol Base cellulose, nano-montmorillonite, glycerin, lignin, etc. are used as toughening modifiers, and wood fiber, waste paper fiber and perlite are used as fillers to modify UF foam. The modified foam prepared has a compressive strength of 170 -220kPa; CN201511003516.2 uses inorganic fibers such as basalt fibers and nanoparticles such as nano-silica to strengthen UF foam, and the compressive strength of the modified foam reaches 120-400kPa; Dai Bencai et al., Guizhou Chemical Industry, 2007, 31(2), 7-8, using sodium lignosulfonate and polyvinyl alcohol to modify urea-formaldehyde foam, when the dosage of the two is 13.7% and 4.4% respectively, the free formaldehyde content of the modified foam is reduced, and the compressive strength reaches 0.8MPa. To sum up, most of the fillers currently used to strengthen modified UF foams are inorganic substances such as nano-montmorillonite, nano-silica, perlite, and basalt fibers. The surface of such fillers lacks functional groups that can interact with the UF matrix. , when it strengthens UF, the interface between the filler and the UF matrix is weak, and the interface debonding is prone to occur; while the commonly used wood fiber has good compatibility with the UF matrix, but its bulk strength and modulus are low, and it is not suitable for UF enhancement is limited. Therefore, the key to obtain toughened UF foams is to select reinforcing fillers with high bulk strength and strong interaction with the matrix to modify UF.

3. Contents of the invention

The purpose of the present invention is to provide a graphene/organic fiber in-situ reinforced urea-formaldehyde foam material and its preparation method for the deficiencies in the prior art, which is characterized in that it will have super high strength, super large specific surface area, high flame retardancy and easy Functionally modified graphene is introduced into the synthesis system of UF resin. Through the study of UF resin/graphene coupling compatibilization technology, the graphene is properly modified to form multiple interface interactions such as chemical bonds and hydrogen bonds. , to achieve complete exfoliation and good dispersion of graphene in the UF resin matrix, and then introduce high-strength organic fibers with good compatibility with UF resin in the foaming and crosslinking process to further increase the strength of the foam material and obtain excellent comprehensive properties. In situ reinforcement of UF foams with graphene/organic fibers.

The object of the present invention is achieved by the following technical measures, wherein the raw material fractions are parts by weight unless otherwise specified.

A kind of starting material formula component of graphene/organic fiber in-situ reinforced urea-formaldehyde foam material is:

Among them, the surfactant is Span-60, Tween-80, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dioctyl succinate sulfonate, sodium laurate sulfate, alkylphenol polyoxyethylene One or more of ethers;

The foaming agent is one or more of ammonium bicarbonate, sodium bicarbonate, n-hexane, cyclohexane, n-pentane, cyclopentane, petroleum ether;

The curing agent is ammonium chloride, formic acid, ammonium sulfate, ethylenediamine hydrochloride, ammonium persulfate, phthalic acid, p-toluenesulfonic acid, p-aminobenzenesulfonic acid, diammonium hydrogen phosphate, ammonium sulfamate one or more;

The organic fiber is one or more of ultra-high molecular weight polyvinyl alcohol fiber, polyimide fiber, aromatic polyamide fiber, aromatic polyester fiber, ultra-high molecular weight polyacrylonitrile fiber, ultra-high molecular weight polyethylene fiber ;

The coupling agent is a polyhydroxy polyether compound with a hydroxyl value of 20-700 mgKOH/g.

Preparation of graphene/organic fiber in situ reinforced urea-formaldehyde foam:

Preparation of graphene modified UF resin liquid:

Add 0.05-20 parts of graphene and 0.05-5 parts of coupling agent to the aqueous formaldehyde solution, ultrasonically disperse at 25-90°C for 0.5-2 hours, then adjust the pH of the system to 7.8-8.5, add the first batch of urea, and After reacting at 70-85°C for 0.5-2 hours, immediately adjust the pH value of the system to 4.5-5.2 with formic acid solution, continue the reaction until the system appears atomized, add the second batch of urea and adjust the pH value of the system after 0.5-2 hours of reaction 7 to 9, add the third batch of urea, react for 5 to 30 minutes, and then unload to obtain graphene-modified UF resin liquid;

Preparation of graphene/organic fiber in situ reinforced urea-formaldehyde foam:

Add 0.05-20 parts of organic fiber and 1-10 parts of surfactant to the graphene-modified UF resin liquid, stir at high speed for 1-5 minutes, add 1-10 parts of foaming agent, continue stirring for 1-10 minutes, add 0.01- 5 parts of curing agent are stirred evenly and poured into a foaming mold, and foamed and cured in a hot oven at 30-120°C to obtain a graphene/organic fiber in-situ reinforced urea-formaldehyde foam material.

Four, the present invention has the following advantages

The present invention aims to prepare a graphene/organic fiber reinforced urea-formaldehyde foam material by in-situ polymerization, which has the following characteristics: graphene is a single-layer two-dimensional honeycomb lattice structure carbon material formed by sp2 hybridized carbon atoms tightly packed , its physical and chemical properties are unique, its strength is 130GPa, 100 times higher than steel, and it is the material with the highest strength at present; its single-layer atomic structure and pore structure make it have a super large specific surface area, the theoretical specific surface area is as high as 2630m ² /g; In addition, graphene is also flame retardant and has excellent flame retardant properties. In the initial stage of UF resin synthesis, graphene is first added to formaldehyde monomer with low viscosity, ultrasonically dispersed, and polyhydroxy polyether compound is used as a coupling agent to treat the surface of graphene to make it uniformly dispersed; Then add urea to the system, and in-situ polymerize to prepare graphene-modified UF resin. On the one hand, polyhydroxy polyether compounds can form intermolecular hydrogen bonds and chemical bonds with the hydroxyl, carboxyl and epoxy groups on the surface of graphene; on the other hand, they have good compatibility with UF systems and can participate in the condensation of UF resins And cross-linking reaction, so as to form a strong interaction between the two-phase interface in the composite system, realize the complete exfoliation and good dispersion of graphene in the UF matrix, and achieve a significant improvement in its mechanical properties with low content of graphene; at the same time in High-performance organic fibers with good compatibility with UF matrix are introduced into the system to further strengthen the modified UF foam. Due to the strong interaction between graphene, organic fiber and UF resin, the modified foam can be endowed with good integrity, and the modified UF foam material with excellent comprehensive performance can be obtained.

5. Specific implementation

The present invention is specifically described below through the examples, it is necessary to point out that the present examples are only used to further illustrate the present invention, and can not be interpreted as limiting the protection scope of the present invention, those skilled in the art can according to the above-mentioned present invention SUMMARY OF THE INVENTION Some non-essential improvements and adjustments are made to the present invention.

Example 1

Add 5 parts of graphene and 0.5 parts of polyhydroxy polyether compound with a hydroxyl value of about 50 mgKOH/g to formaldehyde aqueous solution and sonicate at 50 ° C for 0.5 h, then adjust the pH value of the system to 7.8, add the first batch of urea, at 75 After reacting at ℃ for 1 hour, immediately use formic acid solution to adjust the pH value of the system to 4.8, and react under this condition until the system appears atomized, add the second batch of urea, continue the reaction for 0.5 hours, adjust the pH value of the system to 8.5, and add the second batch of urea Three batches of urea were fed after reacting for 10 minutes to obtain a graphene-modified UF resin solution; in the resin solution, 20 parts of high molecular weight polyvinyl alcohol fibers, 5 parts of sodium dodecylbenzenesulfonate and the mixture of Span-60 were added, After stirring at high speed for 5 minutes, add 3 parts of ammonium bicarbonate, continue stirring for 3 minutes, add 1.5 parts of ammonium chloride and formic acid, stir evenly, pour into a foaming mold, foam and solidify in a hot oven at 40°C to obtain graphite Olefin/organic fiber reinforced urea-formaldehyde foam.

The closed cell rate of the reinforced urea-formaldehyde foam material is over 85%, the density is 0.12kg/m ³ , the compressive strength is 700% higher than that of pure UF foam, and the slag dropping rate is 90% lower than that of pure UF foam.

Example 2

Add 0.1 part of graphene and 0.1 part of polyhydroxy polyether compound with a hydroxyl value of about 400mgKOH/g to formaldehyde aqueous solution and ultrasonicate at 70°C for 2 hours, then adjust the pH value of the system to 8.5, add the first batch of urea, and heat at 75°C After reacting for 2 hours, immediately use formic acid solution to adjust the pH value of the system to 5, react under this condition until the system appears atomized, add the second batch of urea, continue the reaction for 2 hours, adjust the pH value of the system to 8.5, add the third batch of urea, After reacting for 10 minutes, the material was cut to obtain a graphene-modified UF resin solution; 10 parts of polyimide fibers, 10 parts of Tween-80, sodium lauryl sulfate and alkylphenol polyoxyethylene ether mixture were added to the resin solution, After stirring at high speed for 2 minutes, add 5 parts of cyclohexane and cyclopentane, continue stirring for 5 minutes, add 0.5 parts of formic acid and p-aminobenzenesulfonic acid, stir well, pour into a foaming mold, and heat it in a 90°C oven. Bubble and cure, obtain graphene/organic fiber reinforced urea-formaldehyde foam material.

The reinforced foam material has a closed cell rate of 50%, a density of 0.09kg/m ³ , a compressive strength of 400% higher than that of pure UF foam, and a slag dropping rate of 80% lower than that of pure UF foam.

Example 3

Add 10 parts of graphene and 2 parts of polyhydroxy polyether compound with a hydroxyl value of about 600mgKOH/g to formaldehyde aqueous solution and ultrasonicate at 25°C for 1h, then adjust the pH value of the system to 8, add the first batch of urea, and heat at 75°C After reacting for 0.5h, immediately use formic acid solution to adjust the pH value of the system to 4.6, react under this condition until the system appears atomized, add the second batch of urea, continue the reaction for 0.5h, adjust the pH value of the system to 8.5, and add the third batch Urea, after reacting for 10 minutes, cut the material to obtain a graphene-modified UF resin solution; add 5 parts of aromatic polyamide fiber, 3 parts of dioctyl sodium sulfosuccinate and sodium laurate sulfate to the resin solution, and stir at high speed for 5 minutes , add 3 parts of sodium carbonate and n-pentane, continue to stir for 1min, add 2 parts of p-toluenesulfonic acid and phthalic acid, stir well, pour into a foaming mold, and foam in a hot oven at 120°C And solidify, obtain graphene/organic fiber reinforced urea-formaldehyde foam material.

The closed cell rate of the reinforced foam is 8%, the density is 0.08kg/m ³ , the compressive strength is 300% higher than that of pure UF foam, and the slag dropping rate is 50% lower than that of pure UF foam.

Claims (2)

1. a graphene/organic fiber in-situ reinforced urea-formaldehyde foam material and preparation method thereof, is characterized in that the starting raw material formula component of this material is by weight: Among them, the surfactant is Span-60, Tween-80, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dioctyl succinate sulfonate, sodium laurate sulfate, alkylphenol polyoxyethylene One or more of ethers; The foaming agent is one or more of ammonium bicarbonate, sodium bicarbonate, n-hexane, cyclohexane, n-pentane, cyclopentane, petroleum ether; The curing agent is ammonium chloride, formic acid, ammonium sulfate, ethylenediamine hydrochloride, ammonium persulfate, phthalic acid, p-toluenesulfonic acid, p-aminobenzenesulfonic acid, diammonium hydrogen phosphate, ammonium sulfamate one or more; The organic fiber is one or more of ultra-high molecular weight polyvinyl alcohol fiber, polyimide fiber, aromatic polyamide fiber, aromatic polyester fiber, ultra-high molecular weight polyacrylonitrile fiber, ultra-high molecular weight polyethylene fiber ; The coupling agent is a polyhydroxy polyether compound with a hydroxyl value of 20-700 mgKOH/g. 2. the preparation method of graphene/organic fiber in-situ reinforced urea-formaldehyde foam material as claimed in claim 1, is characterized in that the method may further comprise the steps: Preparation of graphene modified UF resin liquid: Add 0.05-20 parts of graphene and 0.05-5 parts of coupling agent to the aqueous formaldehyde solution, ultrasonically disperse at 25-90°C for 0.5-2 hours, then adjust the pH of the system to 7.8-8.5, add the first batch of urea, and After reacting at 70-85°C for 0.5-2 hours, immediately adjust the pH value of the system to 4.5-5.2 with formic acid solution, continue the reaction until the system appears atomized, add the second batch of urea and adjust the pH value of the system after 0.5-2 hours of reaction 7 to 9, add the third batch of urea, react for 5 to 30 minutes, and then unload to obtain graphene-modified UF resin liquid; Preparation of graphene/organic fiber in situ reinforced urea-formaldehyde foam: Add 0.05-20 parts of organic fiber and 1-10 parts of surfactant to the graphene-modified UF resin liquid, stir at high speed for 1-5 minutes, add 1-10 parts of foaming agent, continue stirring for 1-10 minutes, add 0.01- 5 parts of curing agent are stirred evenly and poured into a foaming mold, and foamed and cured in a hot oven at 30-120°C to obtain a graphene/organic fiber in-situ reinforced urea-formaldehyde foam material.