JPH07119391B2 - Undercoat composition for adhesive sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a pressure-sensitive adhesive mainly composed of a polymer having an isobutylene unit as a main component in a pressure-sensitive adhesive sheet, tape or film (hereinafter referred to as a pressure-sensitive adhesive sheet). The present invention relates to a pressure-sensitive adhesive sheet, a tape or a primer composition for a pressure-sensitive adhesive sheet in a film, which improves adhesion to a support such as a polyolefin plastic film.

[Prior Art] Since the polyolefin-based plastic film, which is a support in various pressure-sensitive adhesive sheets, has a low polarity, even if a pressure-sensitive adhesive is applied, the adhesion is low and the interface peels off.

Here, various methods have been proposed in order to improve the adhesion. For example, a method of physically or chemically oxidizing the film surface, or a method of performing corona treatment by corona discharge, flame treatment, radiation treatment, or the like is known.

Examples of the pressure-sensitive adhesive that can obtain good adhesion with the treated surface thus obtained include pressure-sensitive adhesives containing various acrylic acid ester polymers and vinyl ether polymers as the main components. Since these pressure sensitive adhesives have high polarity themselves, there arises a problem that the pressure sensitive adhesive sheet cannot be peeled off.

On the other hand, since the pressure-sensitive adhesive mainly composed of a polymer having an isobutylene unit as the main component has extremely low polarity in its molecular structure, it retains useful properties such as little change with time in the adhesive force after sticking the pressure-sensitive adhesive sheet. Nevertheless, even if the surface treatment of the above-mentioned polyolefin-based plastic film is not performed, sufficient adhesion with the support cannot be obtained without the improvement aimed at activating the pressure-sensitive adhesive. Therefore, as described in JP-A-56-59885, an undercoat composition has been proposed which comprises a mixture of chlorinated polypropylene and one or two of polyisobutylene or butyl rubber.

[Problems to be Solved by the Invention] However, an undercoating agent using the above-mentioned undercoating composition is 10 μm
It cannot be applied as an undercoating agent for pressure-sensitive adhesive sheets used for adherends having a large surface roughness of m, 20 μm. That is,
Even the above-mentioned pressure-sensitive adhesive flows due to the rough surface of the adherend, and the adhesive force after a lapse of time increases. As a result, the adhesion between the undercoating agent and the pressure-sensitive adhesive is not sufficient, so that there is a problem that partial peeling occurs at the interface.

An object of the present invention is to provide a primer composition for a pressure-sensitive adhesive sheet, which has excellent adhesion between the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet and the support.

[Means for Solving the Problems] As described above, the inventors of the present invention have used a pressure-sensitive adhesive mainly composed of a polymer having an isobutylene unit as a main component, which is useful as a pressure-sensitive adhesive sheet, and a support composed of a polyolefin plastic film. Diligent experiments to provide a primer with excellent adhesion,
As a result of repeated research, the present invention has been completed.

That is, the present invention provides a primer composition for a pressure-sensitive adhesive sheet, which comprises 100 to 10% by weight of a chlorinated ethylene-vinyl acetate copolymer and 0 to 90% by weight of a polymer having an isobutylene unit as a main component. It is provided.

The chlorine content of the chlorinated ethylene-vinyl acetate copolymer used in the present invention is preferably 1 to 30% by weight, more preferably 5 to 20% by weight. This is because when the chlorine content exceeds 30% by weight, the adhesiveness between the pressure-sensitive adhesive and the undercoat decreases, and when the chlorine content is less than 1% by weight, the adhesiveness between the support and the undercoat decreases.
Workability is reduced due to insufficient dissolution in solvent.

The polymer having an isobutylene unit as a main component used in the present invention is an isobutylene polymer (polyisobutylene), a random copolymer of isobutylene and normal butylene, a copolymer of isobutylene and isoprene (regular butyl rubber, chlorinated butyl rubber, Brominated butyl rubber, partially crosslinked butyl rubber) or vulcanized or modified products (modified with functional groups such as hydroxyl group, carboxyl group, amino group, epoxy group) and the like.

The primer composition in the present invention is applied to a combination of a pressure-sensitive adhesive mainly composed of a polymer having an isobutylene unit as a main component and a support composed of a polyorifine plastic film, and a chlorinated ethylene-vinyl acetate copolymer alone or It can be used as a blend of it and a polymer having an isobutylene unit as a main component. When used in a formulation,
If the amount of the chlorinated ethylene-vinyl acetate copolymer added to the composition is less than 10% by weight, the adhesion between the undercoating agent and the support will deteriorate, so it is necessary to add 10% by weight or more.

The support of the pressure-sensitive adhesive sheet to which the primer composition of the present invention can be applied is ethylene, in addition to a polyethylene film of propylene homopolymer, a polypropylene film, an ethylene-
Examples thereof include films such as polyolefins such as vinyl acetate copolymers, copolymers containing olefin as a main component, or a mixture thereof.

In addition, in order to obtain a stronger adhesiveness with the undercoat composition, a support whose one surface is surface-treated by a general method to improve wettability is preferably used.

As the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet to which the undercoat composition of the present invention can be applied, the above-mentioned polymer having an isobutylene unit as a main component is used, and a tackifier, a softening agent, a light stabilizer (UV absorber). , Quenching agents, etc.), antioxidants, rust preventives, coloring agents and the like, which are generally used, may be added.

[Function] The technical point of the undercoating composition for pressure-sensitive adhesive sheets of the present invention is to exhibit remarkable adhesion between a pressure-sensitive adhesive mainly composed of a polymer having an isobutylene unit as a main component and a polyorifine-based plastic film. is there. That is, the chlorinated ethylene-vinyl acetate copolymer has a good compatibility with the polymer having an isobutylene unit as a main component, and since it has excellent adhesion to the polyolefin plastic film, it is a good primer. It seems to be.

Further, it is considered that the use of a polymer having the same isobutylene unit as the main component as that of the pressure-sensitive adhesive ensures the adhesiveness with the pressure-sensitive adhesive, resulting in a good primer.

[Examples] Hereinafter, the present invention will be described with reference to Examples, but the scope of the present invention is not limited to these Examples. However, all parts are parts by weight.

Example 1 One-sided corona treatment of a polyethylene film having a thickness of 60 μm with an undercoating agent of a 3 wt% toluene solution of a chlorinated ethylene-vinyl acetate copolymer (Super Clone A manufactured by Sanyo Kokusaku Pulp Co., Ltd., chlorine content 11.5%) It was applied to the surface so that the thickness after drying would be 1 μm, and a 10% by weight toluene solution adhesive of polyisobutylene (Vistanex MML-140 manufactured by Tonex Co., Ltd.) was applied to the surface so that the thickness after drying was 20 μm. To obtain an adhesive sheet.

The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Example 2 50 parts of chlorinated ethylene-vinyl acetate copolymer (Superflon A manufactured by Sanyo Kokusaku Pulp Co., Ltd., chlorine content 11.5%),
A 3% by weight toluene solution of a composition consisting of 50 parts of polyisobutylene (Vistanex MML-140 manufactured by Tonex Co., Ltd.) was used as an undercoat, and the undercoat and the adhesive were applied and dried in the same manner as in Example 1 to obtain an adhesive sheet. And

The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Comparative Example 1 The pressure-sensitive adhesive sheet of Example 1 was applied to one side of a corona-treated surface of a polyethylene film having a thickness of 60 μm so that the thickness after drying was 20 μm to obtain a pressure-sensitive adhesive sheet.

The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Comparative Example 2 Chlorinated Polypropylene (Toyo Kasei Co., Ltd. Hardlen 13L
P, chlorine content of 26%) 50 parts, polyisobutylene (Tonex KK Vistanex MML-140) 50 parts of a toluene solution consisting of 3 wt% of the composition,
A primer and a pressure sensitive adhesive were applied and dried in the same manner as in Example 1 to obtain a pressure sensitive adhesive sheet.

The characteristics of this pressure-sensitive adhesive sheet are shown in Table 1.

Test contents Roll the adhesive sheet onto the adherend (pressure 2 kg / c
m), temperature and pressure of 80 ° C., and 100 kg / cm ² for 1 hour, and after peeling, it was observed whether the adhesive was peeled from the support.

○: No peeling was observed.

Δ: Peeling is observed within the range of 20% or less of the surface area of the adhesive sheet.

X to Δ ... Peeling is observed in the range of 20 to 50% of the surface area of the adhesive sheet.

X: Peeling is observed in the range of 50% or more of the surface area of the adhesive sheet.

The results are indicated by the symbols above.

EFFECTS OF THE INVENTION The primer composition for a pressure-sensitive adhesive sheet of the present invention provides remarkable adhesion between a pressure-sensitive adhesive mainly composed of a polymer having isobutylene as a main component and a polyolefin-based plastic film. It is an extremely useful primer composition as a primer for the production of a protective sheet for a coated plate on the surface.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yutaka Yamaguchi Yutaka Yamaguchi 1500 Ogawa, Shimodate, Ibaraki Hitachi Chemical Co., Ltd. Shimodate Research Laboratory (56) Reference JP-A-56-59885 (JP, A)

Claims (2)

[Claims] 1. A chlorinated ethylene-vinyl acetate copolymer 100.
A basecoat composition for pressure-sensitive adhesive sheets, which comprises 0 to 90% by weight of a polymer having an isobutylene unit as a main component with respect to 10% by weight. 2. The primer composition for pressure-sensitive adhesive sheets according to claim 1, wherein the chlorine content of the chlorinated ethylene-vinyl acetate copolymer is 1 to 30% by weight.