JPS61283672A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. having excellent light resistance, peel strength and retentivity and suitable for use as packaging tape, masking tape and medical pressure-sensitive adhesive tape, by mixing a chlorosulfonated polyolefin with a styrene block copolymer. CONSTITUTION:10-800pts.wt. styrene block copolymer such as styrene/isoprene/ styrene block copolymer or styrene/butadiene/styrene block copolymer and optionally, additives, such as tackifier, softener, antioxidant, etc. are mixed with 100pts.wt. chlorosulfonated polyolefin having a chlorine content of 20-45wt%, a sulfur content of 3wt% or below and an MI of 1-150g/10min and/or chlorosulfonated ethylene/vinyl acetate copolymer. The mixture is melt- kneaded in a kneader.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can be used for packaging tapes, masking tapes, stickers and labels for furniture, home appliances, etc., adhesive paper for carpet cleaners, adhesive sheets for medical use, etc. The present invention relates to a pressure-sensitive adhesive composition.

[Conventional technology]

Conventional pressure-sensitive adhesives (hereinafter referred to as pressure-sensitive adhesives) are solvents that have natural rubber or synthetic rubber as their main component, to which tackifiers, softeners, anti-aging agents, etc. are added, and are dissolved in organic solvents. type, and an aqueous type made by adding the above-mentioned tackifier and the like to emulsify an Acrylic IJ/l/based polymer such as an acrylic acid ester copolymer as the main ingredient.

However, since the former uses an organic solvent, there is a risk of fire due to ignition and toxicity to workers, and -1 water-based type has disadvantages such as poor water resistance and a large cost for the water drying process. was there. In recent years, we have seen the emergence of solvent-free hot-melt adhesives that are mainly composed of thermoplastic polymers. This hot melt type adhesive does not require a drying process, so it is non-polluting and can reduce production costs.

Styrenic block copolymers such as styrene/isoprene block copolymer (hereinafter abbreviated as S) and styrene/butadiene/styrene block copolymer (hereinafter abbreviated as SBS) are thermoplastics with excellent processability. It is often used as a base polymer for the hot-melt adhesive mentioned above in rubber. Hot melt type adhesives using these polymers not only have a low total cost but also have excellent tack and peel strength, but are inferior in light resistance and holding power. That is, their use has been limited because their peel strength decreases when exposed to sunlight, and their holding power is insufficient under high loads.

To solve this problem, methods such as selecting tackifiers and anti-aging agents and optimizing the blending ratio have been taken, but it is important to create a good balance of peel strength and retention at the same time by using these low molecular weight components. The formulation and selection were difficult, and the improvement in light resistance was not satisfactory.

[Problem that the invention seeks to solve]

The purpose of the present invention is to provide a means for improving the holding power and light resistance, which have not been sufficiently satisfactory when conventionally only styrene block copolymers were used as a pace polymer. It is something to do.

[Means for solving problems]

The gist of the present invention is to improve light resistance, peel strength, and holding power by using a mixture of a chlorosulfonated polyolefin and a styrene block copolymer as a paste polymer for an adhesive.

That is, the present invention provides chlorosulfonated polyolefin 100
Styrenic block copolymer 10 to 800 parts by weight
A pressure-sensitive adhesive composition whose main component is a mixture of parts by weight. The details will be explained below.

[Effect]

Adhesives that use a styrenic block copolymer as the base polymer usually contain tackifiers and softeners.

Obtained by melt-kneading fillers and anti-aging agents. As mentioned above, this adhesive has drawbacks such as insufficient holding power when applied to heavy-duty packaging tapes, masking tapes, etc., and loss of adhesive strength when exposed to sunlight for a long period of time. The inventors of the present invention have conducted intensive research to improve these three points, and have found that the problem can be solved by using a mixture of a chlorosulfonated polyolefin and a styrene block darimer copolymer as the base polymer. As the chlorosulfonated polyolefin, chlorosulfonated polyethylene (hereinafter abbreviated as PK-01M) and/or chlorosulfonated ethylene vinyl acetate copolymer (hereinafter abbreviated as ICVA-O9M) is preferable. EVA-
08M has higher adhesion and improved compatibility than BE-08M. PE-08M or IVA-CISM
The raw material polyethylene or raw material ethylene-vinyl acetate copolymer is not particularly limited in production method, but it is preferably one having a melt index of 1 to 1509/10 minutes.

If the melt index is less than 1, the melt viscosity will be too high when kneading with a kneader during compounding, making uniform kneading difficult.
Even when it is dissolved in a solvent, the viscosity of the liquid is too high or it cannot be dissolved. When the melt index exceeds 150, the holding power of the resulting adhesive is not sufficiently improved. Note that high-pressure polyethylene is preferred in terms of ease of kneading and ease of dissolution in a solvent.

Furthermore, if an ethylene-vinyl acetate copolymer is used instead of ordinary polyethylene, a product with better adhesive strength can be obtained, but in this case, the amount of vinyl acetate in the polymer is 5 to 30%.
% by weight is preferable from the viewpoint of the balance between adhesive strength and light resistance.

The manufacturing method of the chlorosulfonated product does not matter, but the amount of chlorine is 20 to 4.
Preferably, the weight is 1% by weight and the amount of sulfur is 6% by weight or less. When the amount of chlorine is less than 20% by weight, due to the influence of crystals in OSM,
If it exceeds 45% by weight, the rigidity will be too strong due to the cohesive force of chlorine, resulting in poor kneading properties in a kneader, poor solubility in solvents, and insufficient improvement in adhesive strength. In addition, the amount of sulfur is 3% by weight.
If it exceeds this, OSM tends to gel due to heat generated during kneading, resulting in poor adhesive strength. In particular, when it is desired to improve the cohesive force, natural crosslinking or thermal crosslinking is possible, so the amount of sulfur is 1.
5% or more is preferable.

IcTA-03M also does not require any particular manufacturing method, but the amount of chlorine is 10
It is preferable that the amount of sulfur is 3% by weight or less. If the amount of chlorine is less than 10% by weight, the cohesive strength of the resulting adhesive will not be sufficiently improved, and if it exceeds 45% by weight, the adhesive strength will not be sufficiently improved.

Also, if the sulfur content exceeds 3% by weight, EV
A-08M gels and becomes less adhesive.

In particular, when it is desired to improve the cohesive force, natural crosslinking or thermal crosslinking is possible, so the amount of sulfur (L3% or more is preferable).

In the present invention, the mixing ratio of SXS and/or SBS and OSM and/or E'VA-03M is 10 to 800 parts by weight, preferably 50 to 300 parts by weight, and 10 to 800 parts by weight, preferably 50 to 300 parts by weight, per 100 parts by weight of S-S and/or 5BS. If it is less than 80 parts by weight, the effect of improving holding power and light resistance will not be sufficient.
If it exceeds 0 parts by weight, the tack will decrease.

Typically, a tackifier is added to the base polymer mixture.

A softener, anti-aging agent, and acid acceptor are added and melted and kneaded in a kneader to form an adhesive. Tackifiers include terpene resins, petroleum resins, rosins, and derivatives thereof, and softeners include process oils based on esters. The resulting adhesive can be used as it is as a hot-melt type adhesive, but it is of course not the purpose of the present invention to dissolve these polymers and compounding agents in an organic solvent such as toluene or ethyl acetate and use them as a solvent type. It's not something that can be done differently.

In the present invention, the acid acceptor is an essential component, and its absence is undesirable because it promotes corrosion of the equipment and gelation of the polymer due to decomposition of the chlorosulfonate.

As the acid acceptor, for example, a metal oxide or an epoxy compound is used.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to improve the light resistance, peel strength, and holding power of an adhesive whose main component is a styrenic block copolymer.

〔Example〕

The present invention will be explained below by giving examples.

Example 1 Melt index 2 (117/10 min, ethylene vinyl acetate copolymer with a vinyl acetate content of 20% by weight was chlorosulfonated in carbon tetrachloride to form a salt at 30% by weight with a sulfur content of 0.8% by weight TA- 03M was obtained. Using this and Califlex TR1107 (Shell Chemical Co., Ltd.) as a pace polymer, an adhesive was prepared using a kneader with a content of 13t in the following procedure.The formulation is shown in Table 1, but the total amount was 8009.
The jacket temperature was maintained at 90°C.

1. The tackifier, anti-aging agent, and acid acceptor were added and melted and kneaded for 10 minutes.

2. 'VA-O3M was added to sxs and melt-kneaded for 20 minutes.

5) A softener was added and melt-kneaded for an additional 20 minutes.

4. Apply the resulting adhesive to release paper using a doctor blade, then transfer it to high-quality paper to prepare an adhesive sheet.

The pole tack, adhesive force (180 degree peeling method), and holding force were measured using the method specified in J Engineering 5-Z-0237. The adhesive sheet was tested by comparing the pole tack before and after irradiation with a high-pressure mercury lamp.

The results are shown in Table 1.

Example 2 Melt index 4 g/l 0 minutes, vinegar [ethylene vinyl acetate copolymer with a vinyl content of 26% by weight was chlorosulfonated to have a chlorine content of 29.7% by weight, sulfur, 1 lcL7
Weight: 1% (7) ETA-08M was obtained. A device similar to Example 1 using this and Kaliflex TR1117 (Shell Chemical Co., Ltd.) as a base polymer.

The adhesive was prepared according to Condition 2 procedure. Example 1 based on this
An adhesive-coated product was prepared and tested in the same manner as above. The formulation and results are shown in Table 1.

Example 3 Melt index 109710 minutes, density α9219/
05M (!:
Califlex TR1101 (Shell Chemical S B S
) was used as a pace polymer to prepare a pressure-sensitive adhesive coated product in the same manner as in Example 1, and it was subjected to a test. The results are shown in Table 1.

Example 4 A solvent-based adhesive was prepared by direct dissolution with a formulation similar to that shown in Example 1. That is, a compounding agent and a solvent were placed in a glass bottle, glass beads were added, and the mixture was dissolved on a ball mill. Using the resulting adhesive, an adhesive sheet was prepared and evaluated in the same manner as in Example 1.

Comparative Example A pressure-sensitive adhesive sheet was prepared and tested in the same manner as in Example 1, except that only S-S was used as the pace polymer, including the formulation and 9 conditions of the apparatus. The results are shown in Table 1.

As can be seen from the above coating 1, according to the present invention, it is possible to obtain a pressure-sensitive adhesive having superior holding power and light resistance compared to the case where only S-S and/or SBS are used as the pace polymer.

Note 1 Escollette 1304 Terpene-modified phenolic resin Shelflex 371N manufactured by Etsuso Naphthenic process oil Aletage RO Tsukiyuki Ihi Katsuyoshi manufactured by Shell Super anti-oxidant Tsukura TNP Anti-aging agent Ferro 909 manufactured by Shinko Ohmukai Epoxy manufactured by Organic Chemical Co., Ltd. Compound MgO + 150 Section M Ibikantai Magnesium Oxide Note 2 Judgment method for holding strength According to JIS Z 02571c, a load of 1 to 9 was applied at 40°C, and the sheet was judged by whether it slipped in 60 minutes.

How to judge light resistance Using a Sunshine Weathermeter (manufactured by Suga Test Instruments), arc irradiation was performed for 2 hours without rainfall, and peel strength before and after irradiation (by 180° peeling method using a stainless steel plate according to JIS Z 0237) ) was measured. Those whose rate of change with respect to the initial value was within ±30% were rated O, otherwise, ×.

Claims (1)

[Claims] (1) A pressure-sensitive adhesive composition whose main component is a mixture of 10 to 800 parts by weight of a styrenic block copolymer to 100 parts by weight of a chlorosulfonated polyolefin.