JPH0443117B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an adhesive tape with writability, and particularly to a polypropylene adhesive tape that has excellent cuttability with a dispenser (tape cutter). (Prior art) Adhesive tapes are required to have various properties depending on the field of use, purpose, etc., but so-called mending tapes, which are used for correcting drawings, etc., have the ability to be written with a pencil; The important quality requirements are that the tape can be copied clearly with the tape attached, and that the tape can be easily cut with a dispenser (tape cutter). In addition to a base material layer containing polypropylene and methylpentene polymer as components and a writing layer containing inorganic fine particles, the present applicant previously formed a crystalline polypropylene layer with a specific thickness that does not substantially contain different polymers or particles, It was proposed to obtain a tape base material with improved cuttability by biaxial stretching (Japanese Patent Publication No. 1-24191, Japanese Patent Application No. 1982-192052).
issue). (Problems to be Solved by the Invention) However, upon further research, it was discovered that the above-mentioned base material for tape has a so-called bowing phenomenon during biaxial stretching during the manufacturing process, which causes the molecular orientation at both ends of the stretched film to change when the film is pulled out. When the tape obtained from both ends of this stretched film is cut with a dispenser, the tape may be cut diagonally from the middle depending on the force applied during cutting (diagonal cut). It turns out that the problem is that it is easy to do. The present invention solves the above-mentioned drawbacks and provides an adhesive tape that can be reliably cut straight with a dispenser and has writability. (Means for Solving the Problems) The gist of the present invention is to provide an adhesive tape comprising an adhesive layer on one side of a laminated base material in which each layer is biaxially stretched. A rough layer consisting of a polymer mainly composed of propylene, a polymer mainly composed of 4-methylpentene-1, and inorganic fine particles is formed on one side of the main layer consisting of coalescence and petroleum resin and/or terpene resin. providing a base material;
An adhesive layer is provided on the other outer surface of the main layer, and each thickness of the above and is relative to the total thickness of the base material;
50-90%; 5-25% of the adhesive tape. The propylene-based polymer used for the rough surface layer in the present invention has a Vikat softening point (measured value according to JISK-7206) of 140°C or lower, especially
It is preferable to use one with a temperature of 130°C or lower. Specifically, a propylene-α-olefin copolymer having the above-mentioned softening point or a mixture of crystalline polypropylene with a high softening point and low-crystalline polypropylene may be used as long as it satisfies the above-mentioned softening point. If a tape having a Vikatto softening point exceeding 140° C. is used, it has the disadvantage that it is difficult to develop surface irregularities due to inorganic fine particles, and the tape is likely to have poor cuttability. In addition, polymers containing 4-methylpentene-1 as a main component have a Vikato softening point of 160°C or less,
Preferably, a temperature of 150°C or lower is used. This softening point is close to the stretching temperature of the base material, and it is possible to prevent interfacial destruction with the propylene-based polymer during stretching. Furthermore, the inorganic fine particles may be those commonly used as inorganic fillers for plastics such as potassium carbonate, tank, clay, etc., and the maximum roughness measured by JISB-0601 of the final adhesive tape can be used.
The grain size is preferably 10 μm or less, with a ten-point average roughness of 2.0 to 6.0 μm, and the maximum grain size is preferably about 10 μm. Next, examples of polymers containing propylene as a main component used in the main layer in the present invention include crystalline polypropylene, propylene-α olefin copolymers such as propylene-ethylene copolymers, or mixtures thereof. Crystalline polypropylene (40-80% by weight) and propylene-ethylene random copolymer (60% by weight) with an ethylene content of 1-10% by weight
~20% by weight), it is easy to obtain an adhesive tape that has better cutting properties and can prevent diagonal cutting of the tape. Petroleum resins for the main layer include aliphatic petroleum resins, alicyclic petroleum resins, aromatic petroleum resins, etc. From this point of view, it is preferable to use an alicyclic petroleum resin that has been completely hydrogenated. Furthermore, as the terpene resin, polymers of α-pinene, β-pinene, dipentene, or modifications thereof can be used. The mixing ratio of the above-mentioned petroleum resin and/or terpene resin to the main layer is preferably in the range of 15 to 35% by weight; if it is less than 15% by weight, the cutting properties will be poor, and if it exceeds 35% by weight, the stretchability of the base material will be poor. There are drawbacks. A crystalline polypropylene layer containing no other components may be provided on one side or both sides of this main layer, and a layer of crystalline polypropylene containing no other components is preferably in the range of 5 to 20% of the total thickness of the base material. This layer can further provide an effect of preventing the tape from being cut diagonally. Although various adhesives can be used for the adhesive layer provided on the base material consisting of the above-mentioned layers, an acrylic acid ester adhesive and a solvent-free type are preferable from the viewpoint of adhesive strength and non-polluting properties. Further, in order to increase the adhesive strength between the base material and the adhesive, a carboxylic acid-modified polypropylene layer may be provided on the surface in contact with the adhesive layer, or the surface of the crystalline polypropylene on the adhesive side may be subjected to corona treatment. The thickness structure of the base material of the tape of the present invention is as follows:
and each thickness of the rough surface layer relative to the total thickness of the base material;
It needs to be in the range of 50-90%, 5-25%, + 75-100%. Thicknesses outside this range have problems with cuttability and strength. The final adhesive tape length, fragrance, breaking strength, and elongation must be 900 to 1200 Kg/cm ² and 80% or less, respectively. By satisfying the properties within this range, an excellent adhesive tape can be obtained. It will be done. Various methods can be considered for manufacturing the adhesive tape made of the above-mentioned base material and adhesive, but after laminating each layer of the base material by a coextrusion method etc., an adhesive is applied, and this laminate is stretched. This method is preferable from the viewpoint of productivity and the like. Regarding the stretching conditions, the stretching ratio in the length direction is 6 to 10 times, and the stretching ratio in the width direction is 2 to 2 times in the range of 5 to 8 times.
Axial stretching is preferred. Stretching temperature is 150-160
It is preferable to stretch at an ambient temperature of °C. The present invention will be explained in detail below using Examples. (Example) Example 1 The composition of the main layer was as shown in Table 1, and on one side of the main layer was a propylene-ethylene random copolymer with a melt index of 7, a Vikat softening point of 128°C, and an ethylene content of 5% by weight. (PP), 4-methylpentene-1 polymer (PMP) with a melt index of 22 and a Vikato softening point of 145°C, and calcium carbonate, and the content of each component is PP=
56% by weight, PWP = 20% by weight, calcium carbonate =
A rough surface layer of 24% by weight was laminated. Furthermore, there is a melt index on the other side of the main layer.
1.6, a crystalline polypropylene layer with a Vikatsu softening point of 150° C. and a carboxylic acid-modified polypropylene layer (Admer OF500, manufactured by Mitsui Petrochemicals) were laminated in the above order to form a base material (///). The thickness composition of each layer in the base material is; 15%, ; 70
%, ;10%, ;5%, and a four-layer unstretched laminated sheet was obtained by coextrusion. Next, an acrylic ester pressure-sensitive adhesive was applied to the layer side of the unstretched laminated sheet without a solvent, and the sheet was stretched at a stretching temperature of 156° C. by 8 times in length and 7 times in width. then 170
A heat treatment was performed at ℃ for 5 seconds to obtain an adhesive tape having a base layer of 35μ and a total thickness of 55μ. Table 1 shows the evaluation results for the dispenser cuttability of the obtained adhesive tape. Dispenser cutting performance was measured using a commercially available dispenser (with a cutting blade thickness of 0.35 mm and a blade spacing of 1.3 Cut the tape by pulling it in a direction of 15 degrees to the cutting blade and twisting it 20 degrees to the left or right. Cutting was attempted 50 times each on the left and right sides, and if the width of the diagonal cut was in the range of 0 to 3 mm, and all of the cuts were successfully made (◎), the success rate of making good cuts was 90% or more, indicating practicality. Those with a success rate of less than 90% were marked (△).

[Table] From Table 1, adhesive tapes Nos. 1 to 3 of the present invention have excellent dispenser cutting properties, especially
It can be seen that No. 2, a mixture of crystalline polypropylene and propylene-ethylene random copolymer, is superior. On the other hand, it can be seen that the conventional product No. 4 has poor dispenser cutting performance and is prone to diagonal cuts. Example 2 The main layer had the same structure as No. 2 in Table 1, and 56% by weight of the propylene-based polymer (PP) shown in Table 2 and 4-methylpentene-1 were applied on one side of the main layer. A rough surface layer consisting of 20% by weight of the main component polymer (PMP) and 24% by weight of calcium carbonate is provided, and a melt index is added on the other side of the main layer.
1.6. A crystalline polypropylene layer with a Vikatsu softening point of 150°C and a carboxylic acid-modified polypropylene layer (Admer QF500, manufactured by Mitsui Petrochemicals) were laminated in the above order to form a base material (///).
The thickness of each layer on the base material was set as shown in Table 2, and a four-layer unstretched laminated sheet was prepared by coextrusion. Further, an adhesive was applied under the same conditions as in Example 1, followed by stretching and heat treatment to obtain an adhesive tape. The evaluation results of the dispenser cuttability, writability, and copyability of the obtained adhesive tape are shown below.
Shown in 2. "Writability" was determined by writing on the tape surface using a pencil with a hardness of 6H, and those that were easy to write on were marked as (◎), and those that were slightly difficult to write on and at the upper and lower limits of practical use were marked as (○). "Copyability" was determined by drawing a straight line on MTC paper (manufactured by Osstritz) using a pencil with a hardness of 6H, pasting each adhesive tape on the straight line, copying with a diazo or electronic copying machine, and checking whether there were any traces of pasting. Those with almost no traces of tape pasting were marked as (◎), those with some traces of pasting but at the lower limit were marked as (○), and those where the straight line drawn by the 6H pencil was difficult to see due to pasting marks were marked as (△).

[Table] * 〓

Claims (1)

[Scope of Claims] 1. An adhesive tape in which each layer is formed by providing an adhesive layer on one side of a biaxially stretched laminated base material, comprising a polymer mainly composed of propylene, and a petroleum resin and/or a terpene resin. A rough surface layer consisting of a polymer mainly composed of propylene, a polymer mainly composed of 4-methylpentene-1, and inorganic fine particles is provided on one side of the main layer to form a base material. An adhesive layer is provided on the other outer surface, and each thickness of the above and is 50 to 90% of the total thickness of the base material.
; An adhesive tape characterized in that the content is in the range of 5 to 25%. 2. The adhesive tape according to claim 1, wherein the rough surface layer is made of a polymer mainly composed of propylene and has a Vikato softening point of 140°C or less. 3. The adhesive tape according to claim 1, wherein the polymer having propylene as a main component in the main layer is crystalline polypropylene, a propylene-ethylene copolymer, or a mixture thereof. 4. The adhesive tape according to claim 3, wherein the polymer mainly composed of propylene in the main layer is a mixture of crystalline polypropylene and a propylene-ethylene random copolymer. 5. The adhesive tape according to claims 1 to 4, characterized in that a cosmetic polypropylene layer containing no other ingredients is provided on one or both sides of the main layer to form a base material. 6. The adhesive tape according to claims 1 to 5, characterized in that the base material is formed by providing a carboxylic acid-modified polypropylene layer on the surface in contact with the adhesive layer. 7. The adhesive tape according to claim 5, wherein the surface of the crystalline polypropylene layer on the adhesive side is subjected to corona treatment.