JPH0228624B2 - NENSETSUCHAKUZAISOSEIBUTSU - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel pressure-sensitive adhesive composition, and more specifically, a novel adhesive composition comprising a block thermoplastic elastomer and a copolymer resin of isoprene, aromatic monoolefin, and aliphatic monoolefin as a tackifier. This invention relates to an adhesive composition. It has been well known that thermoplastic elastomers comprising aromatic monoolefin polymer blocks and conjugated diolefin polymer blocks can be used as base polymers for pressure-sensitive adhesives and hot melt adhesives. For example, A-B-A type (A represents an aromatic monoolefin polymer block, B represents a conjugated diolefin polymer block, the same applies hereinafter).
When the block copolymer is mixed with tackifier resins such as rosin resins and polyterpene resins, and process oil, adhesive compositions useful in various fields such as adhesives, hot melt adhesives, and latex adhesives can be obtained. (Japanese Patent Publication No. 44-17037), and A-B-A-B type block copolymers and A-B-A
When a tackifier resin is mixed with the -B-A type block copolymer, compositions useful as various pressure-sensitive adhesives can be similarly obtained (Japanese Patent Publication No. 49-330).
Furthermore, recently, attempts have been made to use a combination of an A-B-A type block copolymer and an A-B type block copolymer (US Defense Patent No. T100203). However, although the compositions obtained using these conventional techniques are superior in terms of adhesive strength and holding power compared to pressure-sensitive adhesive compositions obtained using natural rubber as a base elastomer, they are inferior in terms of initial adhesive strength. This tendency is particularly noticeable when a block copolymer derived from styrene and 1,3-butadiene (hereinafter sometimes abbreviated as S/B block copolymer) is used as a thermoplastic elastomer. It was hot. Therefore, the present inventors conducted intensive studies to improve the shortcomings of the prior art and develop a pressure-sensitive adhesive composition that has excellent initial adhesion as well as excellent adhesion and holding power. The inventors have discovered that it is effective to use hydrocarbon resin, and have completed the present invention. Thus, according to the present invention, (A) a thermoplastic elastomer comprising an aromatic monoolefin polymer block and a conjugated diolefin polymer block, and (B) 25 to 70% by weight of isoprene and an aromatic monoolefin as a tackifier. An adhesive compounded with a hydrocarbon resin obtained by cationic polymerization of a monomer mixture consisting of 25 to 70% by weight and 5 to 40% by weight of an aliphatic monoolefin in the presence of an aluminum halide catalyst. A composition is provided. In the present invention, 25 to 70% by weight of isoprene,
Preferably 30 to 65% by weight, aromatic monoolefin 25 to 70% by weight, preferably 30 to 65% by weight, aliphatic monoolefin 5 to 40% by weight, preferably 10
A solid hydrocarbon resin, preferably a hydrocarbon resin having a softening point of 50 to 120° C., obtained by subjecting a monomer mixture containing 30% by weight to thionic polymerization using an aluminum halide catalyst is used as the tackifier. In the present invention, it is essential to use isoprene as the conjugated diolefin component,
Even if other conjugated diolefins such as 1,3-pentadiene and 1,3-butadiene are used, they are inferior in terms of the balance of initial adhesive strength, adhesion strength, and retention strength, and they also have poor heat resistance when used as hot melt adhesives. It is also insufficient in terms of stability and odor. The usage ratio of isoprene is as above,
If the ratio exceeds 70% by weight, high molecular weight polymers are likely to be produced which adversely affect the compatibility with the thermoplastic elastomer, and if this ratio is less than 25% by weight, a large amount of liquid low molecular weight polymer will be produced during the polymerization reaction. It is produced as a by-product and the softening point of the resin is significantly lowered. On the other hand, examples of aromatic monoolefins include styrene, α-methylstyrene, vinyltoluene, isopropenyltoluene, etc., and any of them can be used as a tackifier for adhesive compositions. Hydrogen resin can be obtained. The proportion of the aromatic monoolefin in the monomer mixture is as described above, and outside this range, the compatibility with the thermoplastic elastomer decreases. In addition, as the aliphatic monoolefin, isoptylene, butene-1, cis-butene-2, trans-butene-2, pentene-1, cis-pentene-2, trans-pentene-2, 2-methyl-butene-1 , 2-methyl-butene-2, diisobutylene, cyclopentene, cyclohexene, etc., and those having 4 to 8 carbon atoms are particularly preferred. By using such aliphatic monoolefin, the compatibility with the thermoplastic elastomer is improved and the adhesive performance is also improved, but when the proportion is 40% by weight,
If it exceeds this, the resin yield will decrease, a large amount of liquid low molecular weight polymer will be produced as a by-product, and the softening point of the resin will drop significantly. Furthermore, other polymerizable components such as 1,3-butadiene, 1,3-pentadiene, cyclopentadiene, dicyclopentadiene, methylcyclopentadiene, indene, methylindene, etc. within a range that does not essentially impair the effects of the present invention. may be included, but it is desirable that the content thereof be as small as possible. The hydrocarbon resin used in the present invention can be obtained by cationically polymerizing such a monomer mixture in the presence of an aluminum halide catalyst according to a conventional method. Examples of catalysts used include aluminum halides such as aluminum chloride, aluminum bromide, and complexes of these with ligands such as hydrochloric acid, halogenated hydrocarbons, aromatic hydrocarbons, and the like. In the present invention, it is an essential requirement to use such an aluminum halide catalyst, and the effects of the present invention can also be obtained even if a boron halide catalyst, which is commonly used in the production of aromatic petroleum resins, is used. I can't. Further, as the diluent, any of aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons can be effectively used, but aromatic hydrocarbons are particularly preferred. This solvent is usually used in a proportion of 20 to 1000 parts by weight, preferably 50 to 500 parts by weight per 100 parts by weight of monomer. Polymerization is usually carried out at a temperature of 0 to 120°C, preferably 20 to 100°C, and the pressure of the reaction system may be above or below atmospheric pressure. Reaction times generally can vary from a few seconds to 12 hours or more. After the polymerization is completed, the desired hydrocarbon resin is obtained by processing and drying according to a conventional method. The thermoplastic elastomer that is the base polymer of the composition of the present invention is a block copolymer derived from an aromatic monoolefin and a conjugated diolefin, and is generally used as a base polymer in the field of adhesives. Any formula (A-B) n or (A-B
) _o-1 ---A (wherein A is substantially an aromatic monoolefin polymer block, B is substantially a conjugated diolefin polymer block, and n is an integer from 2 to 10) The aromatic monoolefin content is 10 to 70% by weight, preferably 10 to 55% by weight, and the average molecular weight is 25,000 to 500,000, preferably 40,000 to 40,000.
200,000 block copolymer. Specific examples of the aromatic monoolefin constituting the block copolymer include styrene, α-methylstyrene, vinyltoluene, etc., but styrene is usually used. Specific examples of the conjugated diolefin include 1,3-butadiene, isoprene, and 1,3-pentadiene. Such block copolymers also include so-called ``tapered'' copolymers containing a ``substantially conjugated diolefin polymer block'' of copolymers containing small amounts of aromatic monoolefin units in proportions that gradually increase from one end of the block to the other. "Block copolymers" are also included, and if necessary, AB type block copolymers may be appropriately blended. All of these block copolymers are known substances, and can be prepared using known methods using lithium-based initiators, such as Japanese Patent Publication No. 19286-1986 and Japanese Patent Publication No. 23798-1973.
It is manufactured according to the method described in Japanese Patent Publication No. 43-17979, Japanese Patent Publication No. 43-2394, etc. The blending ratio of the base polymer and hydrocarbon resin is not necessarily uniform depending on the use of the adhesive composition, but generally 30 to 250 parts by weight, preferably 40 to 150 parts by weight of the hydrocarbon resin per 100 parts by weight of the base polymer. is blended. In addition to the block type base polymer and hydrocarbon resin, other base polymers and tackifier resins may also be used in combination with the block type base polymer and the hydrocarbon resin to the extent that they do not essentially impede the effects of the present invention. It is also possible to add softeners, antioxidants, fillers, etc. The compositions of the invention are manufactured according to any method. For example, each component can be heated and kneaded by putting it into a blade mixer equipped with blades with an appropriate shape for kneading, and it can be continuously kneaded using an extruder-type kneader equipped with a single or twin screw. It can also be manufactured. Alternatively, each component can be stirred and mixed in the presence of a solvent such as toluene to form an adhesive solution. The solution type, hot melt type, etc. adhesive composition thus obtained can be used to manufacture various adhesive tapes and adhesive label products by uniformly applying it to a desired base material using a coating machine. Further, after heating and kneading, the mixture can be placed in a container such as a paper drum, cooled, and then remelted to be used for hot melt bonding. The present invention will be explained in more detail with reference to Examples below. Note that all parts and percentages in Reference Examples and Examples are based on weight. Reference Example 1 After charging 100 parts of benzene and 1.2 parts of aluminum chloride or 2.0 parts of boron trifluoride diethyl etherate, gradually add 100 parts of a monomer mixture having the composition shown in Table 1 and copolymerize at 65°C. Various hydrocarbon resins were produced by this process. The softening point was measured according to the ring and ball method specified in JISK-2531, and the hue was measured according to Gardner chromaticity specified in ASTM D1544-63T. The results are shown in Table 1.

【table】

[Table] Example 1 A-B-A type styrene-butadiene block copolymer (Krayton 1101, polystyrene content 30
%, manufactured by Ciel Chemical Co., Ltd.) 100 parts, tackifier resin 100
1 part, naphthenic process oil (Ciel Flex 371, manufactured by Ciel Chemical Co., Ltd.) 30 parts and antioxidant 1
A part was dissolved and mixed in toluene to prepare an adhesive solution with a nonvolatile content concentration of 40%. Next, this solution was applied onto a 25μ thick polyester film to create an adhesive tape with an adhesive thickness of 25μ, and the initial adhesive strength
Adhesion and holding power were measured. The tackifier used was not only the hydrocarbon resin obtained in the reference example (the tackifier alpha in Table 2 corresponds to that in Table 1), but also conventional thermoplastic elastomer-based tackifiers for comparison. Various tackifier resins that are used industrially as tackifiers for elastomer adhesives were simultaneously evaluated. The initial adhesive strength is based on JISZ-0237 at 23℃.
Attach a 10 cm length of adhesive tape with the sticky side facing up to the slope of a stainless steel plate with a 30 degree inclination angle, and tape 30 different sizes from 3/32 inch to 1 inch in diameter from a position 10 cm above the slope. The size of the largest diameter ball that stops on the adhesive tape when rolled at an initial speed of 0 is the size of the ball, and the adhesive strength is based on JIS Z-0237. The adhesive tape was attached to a 10 mm x 100 mm length and measured by peeling it in a 180 degree direction at a speed of 200 mm/min at 23°C. Attach adhesive tape so that the area of ×10 mm touches each other, and
The time required for the adhesive tape to fall off from the stainless steel plate was measured under a load of 1 kg.
The results are shown in Table 2. From the results in Table 2, it can be seen that the adhesive of the present invention exhibits an initial adhesive strength equal to or higher than that of low softening point rosin ester, and also has an excellent balance of initial adhesive strength, adhesive strength, and holding power. . In contrast, compositions obtained using ordinary aliphatic hydrocarbon or polyterpene resins (Experiment No. 11 to
12) showed almost no performance as an adhesive, and when resins obtained with rosin ester or boron trifluoride catalysts were used (experiment numbers 13 and 8), the balance between holding power and adhesive strength was poor. Inferior. Example 2 A-B-A styrene-isoprene block copolymer (Krayton 1107, polystyrene content 14
%, manufactured by Ciel Chemical Co., Ltd.) 100 parts, tackifier resin 100
1 part, naphthenic process oil (Ciel Flex 371, manufactured by Ciel Chemical Co., Ltd.) 20 parts and antioxidant 1
The adhesive physical properties were evaluated in the same manner as in Example 1, except that the adhesive was blended. The results are shown in Table 3. From the results in Table 3, the adhesive of the present invention exhibits an initial adhesive strength equal to or greater than that of adhesives obtained using rosin ester or polyterpene resin, and also has an excellent balance of adhesive strength and holding power. I understand that.

【table】

【table】

【table】

[Table] * Same as Table 2

Claims (1)

[Claims] 1 A thermoplastic elastomer consisting of an aromatic monoolefin polymer block and a conjugated diolefin polymer block is added with (B) isoprene as a tackifier.
Carbonization obtained by cationic polymerization of a monomer mixture consisting of 25 to 70% by weight of aromatic monoolefin, 25 to 70% by weight of aromatic monoolefin, and 5 to 40% by weight of aliphatic monoolefin in the presence of an aluminum halide catalyst. An adhesive composition containing a hydrogen resin.