JPS584752B2 - Netsukatsusenenchaxoseibutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to heat-activated adhesive compositions that are normally non-tacky, become tacky upon activation by heating, and can remain tacky for a period of time after activation.

Pressure-sensitive adhesives that are commonly used in the past have the advantage of being easy to stick to adherends, but because they are always sticky, they can attract dust or inadvertently adhere to other objects. The disadvantage was that things often happened.

In addition, since hot melt adhesives are usually non-tacky, they do not have the above-mentioned disadvantages of pressure-sensitive adhesives and are easy to handle. In order to adhere the label provided with the can to the can, heat and pressure must be applied while the label and the can are in contact, which is a cumbersome process and requires expensive equipment.

The present invention has been made in view of the above-mentioned current situation, and is intended to provide a composition that has the advantages of both pressure-sensitive adhesives and hot-melt adhesives. It becomes sticky when heated to
The object of the present invention is to provide a heat-activated adhesive composition that can maintain its adhesive properties for some time even after heat is removed.

The present inventors believe that alternating copolymers and random copolymers cannot be used as bases for the adhesive composition of the present invention because of their weak cohesive strength, and that they can be partially crosslinked to improve their cohesive strength. As a result of experiments, we learned that block copolymers of styrene and butadiene or isoprene do not necessarily have to be partially cross-linked because they have poor compatibility with plasticizers and other ingredients. Noting that it has excellent cohesive strength as it is and has good compatibility with blended components such as plasticizers, as a result of various experiments, we mixed specific amounts of tackifier and special plasticizer with the above block copolymer. The inventors have discovered that the intended purpose can be achieved by doing so, and have come up with the present invention.

That is, the heat-activated adhesive composition according to the present invention contains 5 to 100 parts by weight of a tackifier and 50 to 400 parts by weight of a crystalline plasticizer to 100 parts by weight of a block copolymer of styrene and butadiene or isoprene. It is characterized by the fact that

In the block copolymer of the present invention, the polystyrene block has a molecular weight of about 6,000 to 120,000, the polybutadiene or polyisoprene block has a molecular weight of about 15,000 to 200,000, and the polystyrene content is about 18
~48 mol% is preferred.

Tackifiers are components that increase tackiness when activated by heating, and include alkylphenol resins, terpenephenol resins, aromatic petroleum resins, coumaron indene resins, styrene resins, olefin resins, etc. There are a variety of them, but there are no particular limitations.Chikarabutsugin, its derivatives, and terpene resins are preferred because they have good compatibility with block copolymers and crystalline plasticizers.

Furthermore, the crystalline plasticizer, which is an important component in the present invention, is in a solid crystalline state at temperatures below the softening point, and once melted, it does not crystallize immediately even after the heat is removed, but rather slowly crystallizes. Specific examples thereof include disiloxhexyl phthalate and diphenyl phthalate.

The present invention utilizes the slow crystallization effect of the crystalline plasticizer after heat melting, and by appropriately selecting the type and number of parts of the plasticizer, adhesive retention of the adhesive composition after heat activation is achieved. Time can be changed relatively freely.

Next, regarding the number of parts of the adhesive composition component according to the present invention, 5 to 5 parts of the tackifier is added to 100 parts by weight of the block copolymer of styrene and butadiene or isoprene.
100 parts by weight, and the crystalline plasticizer is 50 to 400 parts by weight.

If the amount of the tackifier is less than 5 parts by weight, the adhesive strength of the resulting adhesive composition upon thermal activation will be too small to be practical;
If it exceeds 100 parts by weight, the adhesive composition becomes constantly sticky and a thermally active adhesive composition cannot be obtained.

In addition, if the amount of crystalline plasticizer is less than 50 parts by weight, the desired heat-activated adhesive composition will not be obtained because the desired heat-activated adhesive composition will become sticky as when the tackifier is added in excess of 100 parts by weight, and if the amount exceeds 400 parts by weight, The adhesion retention time after thermal activation is too short to be practical, and both are unfavorable.

Note that there is no problem in adding a known anti-aging agent to suppress deterioration of the heat-activated adhesive composition.

In addition, when using an anti-aging agent, block copolymer 1
It may be added in an amount of about 0.5 to 2 parts by weight per 00 parts by weight.

The heat-activated adhesive composition of the present invention is generally prepared by dissolving the ingredients in an organic solvent such as toluene, benzene, etc. and applying it to a film-like base material such as paper, cloth, or plastic film.
It is used by being impregnated or melt-laminated onto a substrate.

The heat-activated adhesive composition of the present invention as described above is usually non-adhesive, so unlike pressure-sensitive adhesives, it does not attract dust or the like.
It does not inadvertently adhere to other objects, and even after being activated by heat, it remains sticky for a while even after the heat is removed, so it can be easily heated by hand with a hairdryer, iron, etc. Can be used for pasting work.

Also, bonding of treated surfaces of silicone-treated paper, or AB
It is fully applicable to bonding S plates, PVC plates, etc. where satisfactory results cannot be obtained with ordinary adhesives.

Furthermore, by appropriately selecting the type and number of crystalline plasticizers, the adhesive retention time after heat activation of the adhesive composition can be set relatively freely, making it useful for clearly indicating the expiration date of fresh foods and fruits. It can also be used effectively.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, "parts" in the examples mean parts by weight.

Example 1 20 parts of toluene, 100 parts of a styrene-phtacyene copolymer (manufactured by Shell Chemical Co., Ltd., Cariflex TR1101, styrene content 33 mol%), 20 parts of FF Kuchijin (manufactured by Arakawa Forestry Co., Ltd.) as a tackifier, and Dicyclohexacyl phthalate is added in varying amounts of 50, 100, 150, 200, and 350 parts and stirred to dissolve.

Next, a piece of Japanese paper with a thickness of 50 microns was immersed in each solution, pulled up, heated and dried in a hot air circulation dryer at 100°C for 2 minutes, and then left at room temperature for 10 days to heat-activate it to make it completely sticky. A non-adhesive sheet was obtained.

Table 1 shows the adhesive retention time of the pressure-sensitive adhesive sheet thus obtained after heat activation and the adhesive strength upon heat activation.

Adhesive retention time is the time it takes for the heat-activated adhesive sheet to lose its adhesive properties when left at room temperature (20°C) after being activated by heating at 100°C for 10 seconds, and is determined by the adhesiveness to the fingertips. It is.

Further, the adhesive strength was measured by adhering a heat-activated adhesive sheet to an ABS plate and using a 180° peeling method, and the measurement was performed according to JISO-2336.

For comparison, data obtained by blending 30 parts and 450 parts of dicyclohexyl phthalate are shown.

Next, Table 2 shows the changes over time in the adhesive strength of the heat-activated adhesive sheets to various objects.

Incidentally, a sample containing 100 parts of dicyclohecylphthalate was used, and the measurement was performed according to JISC-2336.

Note that the measured values in Tables 1 and 2 are all average values of 10 samples, and the unit of adhesive strength is kg 72 cm width.

Example 2 Styrene-isoprene copolymer (manufactured by Shell Chemical Co., Ltd., Cauliflakes TR1107, styrene! 30 mol%) 10
0 parts, MS-1150 (manufactured by Yasushi Oil Co., Ltd., terpene resin)
30 parts, 80 parts of diphenyl phthalate and 200 parts of toluene.
After dissolving the mixture in the following manner, a heat-activated adhesive sheet was obtained in the same manner as in Example 1.

The adhesive sheet was activated at 100°C for 10 seconds, and its adhesive retention time and adhesive strength to an ABS board were measured in the same manner as in Example 1. The adhesive retention time was 3 hours and 10 minutes, and the adhesive strength was 1. .8k9/2cm wide (measured values are average values of 10 samples each).

According to the above examples, the heat-activated adhesive sheet using the heat-activated adhesive composition of the present invention retains its adhesive properties for a while even after heat is removed after heat activation, and the adhesive retention time is determined by crystallization. It can be seen that it can be set relatively freely depending on the type of plasticizer and the number of parts mixed.

Claims (1)

[Claims] 1 5 to 10 parts by weight of tackifier per 100 parts by weight of block copolymer of styrene and butadiene or isoprene
1. A heat-activated adhesive composition characterized in that it contains 0 parts by weight of a crystalline plasticizer and 50 to 400 parts by weight of a crystalline plasticizer.