JP2518456B2 - Undercoat composition for adhesive film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a primer composition for an adhesive film, which improves the adhesion between an adhesive mainly composed of acrylic rubber and a polyolefin plastic film.

[Conventional technology]

In surface protective sheets or films such as various adhesive tapes, metal plates, resin plates, and plywood, the polyolefin-based plastic film that is the support has low polarity, so even if a pressure-sensitive adhesive is applied, the adhesiveness is low and interface peeling occurs. .

Therefore, various methods have been proposed in order to improve the adhesion. For example, methods are known in which the film surface is physically or chemically oxidized or corona-treated by corona discharge, or an undercoating treatment with a chlorinated polyolefin is performed.

Chlorinated polyolefins have good adhesion to polyolefin-based plastic films but poor adhesion to adhesives, so they are disclosed in JP-A-58-32661 and JP-A-5-32661.
As described in 9-53557, an undercoat agent such as a mixture of a chlorinated polyolefin and an acrylate copolymer having a hydroxyl group or a graft product of an acrylic copolymer is proposed, and a good evaluation is obtained. ing.

However, it has been found that these methods cannot be applied as an undercoating agent for an adhesive film used for an adherend having a large surface roughness.

In other words, with the recent trend toward high-grade adherends, the surface roughness of the coating plate used for roofs and walls for building materials, VCRs for home appliances, housings for stereo amplifiers and tuners, etc. is 10 μm or more. In some cases, it has become 20 μm or more. That is, the surface of the coating is roughened to reduce the gloss and give a high-grade feeling. In particular, coating plates for building materials are rapidly increasing due to an increase in the number of housing starts.

[Problems to be Solved by the Invention]

For coated plates with large surface roughness as described above,
To improve the flexibility of the pressure-sensitive adhesive of the pressure-sensitive adhesive film so that the pressure-sensitive adhesive deforms and adheres well to a rough surface to ensure good stickiness, while suppressing deterioration of the adhesive strength over time. It is necessary to appropriately crosslink the adhesive.

For example, the present inventors previously mentioned in Japanese Patent Application No. 64-2670 a surface for a rough coated plate using a pressure sensitive adhesive composed of a specific glass transition temperature, a high molecular weight acrylic rubber and a methylol compound having a specific structure. Proposed a protective film. However, with the above surface protection film, it is not possible to deal with all coated plates with various rough surfaces, and the adhesive flows to the rough surface of the adherend after a lapse of time, increasing the adhesive strength after a lapse of time. However, the adhesiveness between the support 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 an undercoating composition having excellent adhesiveness between an acrylic rubber-based pressure-sensitive adhesive and a polyolefin-based plastic film.

[Means for solving the problem]

The present inventors have focused their attention on how to improve the adhesiveness between the adhesive and the chlorinated polyolefin based on the highly adhesive chlorinated polyolefin having a high adhesiveness mainly with the acrylic rubber and the film, and earnestly experimented, As a result of repeated research, the present invention has been completed.

That is, the present invention is a composition comprising (1) 10 to 90% by weight of a chlorinated polyolefin having a chlorine content of 15 to 40% by weight and 0.1 to 10% by weight of a functional group, and (2) 90 to 10% by weight of an acrylic rubber. (3) 1 to 20 parts by weight of an isocyanate reaction catalyst is blended with 100 parts by weight of the product.

Examples of the chlorinated polyolefin used in the present invention include chlorinated polypropylene, chlorinated polyethylene and the like, and it is necessary that a functional group is provided with a group having reactivity with isocyanate such as a hydroxyl group or a carboxyl group. The added one is preferably used.

If the content of the functional group imparted to the chlorinated polyolefin is less than 0.1% by weight, the adhesiveness between the adhesive and the undercoating agent will decrease, and if it exceeds 10% by weight, the adhesive will harden due to excessive crosslinking and the adherend will be adhered. Adhesiveness to is reduced.

The chlorine content of chlorinated polyolefin is 15-40% by weight,
It is preferably 20-30% by weight, which has a chlorine content of 15%.
When it is less than 40% by weight, the solubility in the solvent is insufficient and the workability is deteriorated, and when it exceeds 40% by weight, the adhesion to the support is deteriorated.

Further, the isocyanate reaction catalyst used in the present invention is triethylamine, cobalt naphthenate, benzyltrimethylammonium hydroxide, stannous chloride, tetra-n-butyltin, stannic chloride, tri-.
Examples thereof include n-butyltin acetate, n-butyltin trichloride, trimethyltin hydroxide, dimethyltin dichloride and dibutyltin dilaurate. Among them, dibutyltin dilaurate is particularly preferable.

The composition ratio of the chlorinated polyolefin (1) and the acrylic rubber (2) is 10% by weight of the chlorinated polyolefin.
When the amount is less than the above range, the adhesion between the support and the undercoating agent is deteriorated, and when it exceeds 90% by weight, the tackiness and the adhesion between the undercoating agent are deteriorated.

When the amount of the isocyanate reaction catalyst is less than 1 part by weight per 100 parts by weight of the above composition, the reaction between the functional group and the isocyanate group cannot be completed, and the adhesiveness between the adhesive and the primer is insufficient, so that it cannot be used immediately after preparation. However, if it exceeds 20 parts by weight, bleed-out occurs and the adherend is contaminated.

The pressure-sensitive adhesive film to which the undercoating agent of the present invention can be preferably applied has a polyolefin-based plastic as a support and is coated with a pressure-sensitive adhesive containing 1 to 10 parts by weight of a polyfunctional isocyanate per 100 parts by weight of acrylic rubber.

As the acrylic rubber, a copolymer obtained by copolymerizing an acrylic acid alkyl ester monomer or a methacrylic acid alkyl ester monomer and a functional group-imparting monomer is preferably used. The acrylic acid alkyl ester monomer and methacrylic acid acrylic ester monomer preferably have an alkyl group having 1 to 8 carbon atoms. Among these monomers, for example, butyl acrylate and acrylic acid 2
-Hexyl, methyl methacrylate, ethyl methacrylate and the like are preferably used. Also, acrylic ester,
Regardless of the type of methacrylic acid ester, two or more types can be used in combination.

In addition, a suitable amount of a vinyl-based monomer copolymerizable with the acrylic acid alkyl ester monomer and the methacrylic acid alkyl ester monomer, such as styrene, vinyl acetate, acrylonitrile, and methacrylonitrile can be used.

Examples of the functional group-containing monomer that is copolymerized with acrylic rubber include (1) hydroxyl group, (2) carboxyl group, and other monomers that are reactive with isocyanate as the functional group. Specific monomers are as follows. Is.

(1) As the hydroxyl group-containing monomer, acrylic acid 2-
Hydroxyethyl, 2-hydroxybutyl acrylate,
2-hydroxypropyl methacrylate, methacrylic acid 2
-Hydroxyethyl and the like.

(2) Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid.

Two or more kinds of these functional group-containing monomers can be used in combination.

A compound having two or more isocyanate groups in the molecule is used as the polyfunctional isocyanate, and examples thereof include tolylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, biphenylene diisocyanate, tetramethylene diisocyanate,
Hexamethylene diisocyanate, hexamethylene diisocyanate, xylene diisocyanate and the like are preferably used.

If the amount of the polyfunctional isocyanate is less than 1 part by weight, the adhesion between the pressure-sensitive adhesive and the undercoating agent will be deteriorated, and if it is more than 10 parts by weight, the pressure-sensitive adhesive will be hard and the adhesion to the adherend will be deteriorated.

As described above, the pressure-sensitive adhesive has two components of acrylic rubber and polyfunctional isocyanate as essential components, but a tackifier, a softening agent, an ultraviolet absorber, an antioxidant, a rust preventive, a crosslinking accelerator, It goes without saying that a compounding agent that is usually compounded with the pressure-sensitive adhesive such as a colorant may be added.

Examples of the support used in the present invention include ethylene, a polyethylene film of propylene homopolymer, a polypropylene film, a polyolefin such as an ethylene-vinyl acetate copolymer, or a copolymer or mixture containing olefin as a main component. .

[Action]

The technical point of the undercoating agent for pressure-sensitive adhesive films of the present invention is to exhibit remarkable adhesion between the pressure-sensitive adhesive mainly composed of acrylic rubber and the polyolefin-based plastic film.

The primer is composed of a chlorinated polyolefin having a specific functional group, an acrylic rubber and an isocyanate reaction catalyst. Intermolecular force between the chlorinated polyolefin in the primer and the polyolefin plastic film, intermolecular force between the chlorinated polyolefin and acrylic rubber in the primer and the adhesive, and further functional groups in the primer and the adhesive It is considered that the cohesive bond force generated through the isocyanate bonds the adhesive, the primer and the support with remarkable adhesion. Moreover, since an isocyanate reaction catalyst is added to form a covalent bond, remarkable adhesiveness can be obtained immediately after the production of the adhesive film.

It goes without saying that the adhesiveness between the pressure-sensitive adhesive and the polyolefin-based plastic film is higher than the corona treatment when the above-mentioned undercoating agent is used.

As mentioned above, the above-mentioned three components are necessary as this primer, and chlorinated polyolefin alone is not effective,
In fact, it is the same as when there is no top and bottom coating agent, while the case where only acrylic rubber is used is equivalent to the case where no bottom coating agent is used and has no similar effect.

Contamination of the pressure-sensitive adhesive film obtained by applying the undercoating agent to the adherend is extremely low as in the case where the undercoating agent is not used since the chlorinated polyolefin is held by the primary bond by the polyfunctional isocyanate.

〔Example〕

Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples. However, all parts are parts by weight.

Example 1 50 parts of hydroxylated chlorinated polypropylene (S-180 manufactured by Sanyo Kokusaku Pulp Co., OH content 1.7%, chlorine content 22%, both solid content) acrylic rubber 50 parts (Toa Paint ( Ltd. PS-220, Mw = 1.2 million, Tg = -43
Dibutyltin dilaurate 5 parts (manufactured by Tokyo Kasei Kogyo Co., Ltd.) A 4% by weight toluene solution of the above mixture was prepared and used as a primer on one side of an unstretched polypropylene film having a thickness of 40 μm and a thickness after drying of 1 μm. 100 parts of acrylic rubber (PS-220 manufactured by Toa Paint Co., Ltd., Mw = 1.2 million, Tg = −43)
C.) Hexamethylene diisocyanate 5 parts (Sumitomo Biurethane Co., Ltd. Sumidule N) was applied to a 10 wt% toluene solution pressure sensitive adhesive so that the thickness after drying would be 20 μm to obtain a pressure sensitive adhesive film.

 The characteristics of this adhesive film are shown in Table 1.

Example 2 Example 1 was applied to one side of a polyethylene film having a thickness of 60 μm.
In the same manner as above, a primer and a pressure sensitive adhesive were applied and dried to obtain a pressure sensitive adhesive film.

 The characteristics of this adhesive film are shown in Table 1.

Comparative Example 1 The pressure-sensitive adhesive of Example 1 was dried on one side (corona-treated surface) of an unstretched polypropylene film having a thickness of 40 μm to give a thickness after drying.
The adhesive film was applied so as to have a thickness of 20 μm.

 The characteristics of this adhesive film are shown in Table 1.

Comparative Example 2 4% toluene consisting of a mixture of 50 parts of the chlorinated polypropylene of Example 1 (S-180 manufactured by Sanyo Kokusaku Pulp Co., Ltd.) and 5 parts of dibuutiltin dilaurate on one side of a 40 μm thick unstretched polypropylene film. The solution was applied as an undercoat so that the thickness after drying was 1 μm, and the adhesive of Example 1 was applied thereon so that the thickness after drying was 20 μm to obtain an adhesive film.

 The characteristics of this adhesive film are shown in Table 1.

Comparative Example 3 50 parts of the chlorinated polypropylene of Example 1 (S-180 manufactured by Sanyo Kokusaku Pulp Co., Ltd.) and acrylic rubber (PS-220 manufactured by Toa Paint Co., Ltd.) 50 on one side of an unstretched polypropylene film having a thickness of 40 μm. A 4% by weight toluene solution consisting of a mixture with 1 part was applied as an undercoat so that the thickness after drying would be 1 μm, and the adhesive of Example 1 was applied thereon so that the thickness after drying was 20 μm. It was applied to and used as an adhesive film.

 The characteristics of this adhesive film are shown in Table 1.

[Effect of the invention] The primer composition for an adhesive film of the present invention provides remarkable adhesion between an adhesive mainly composed of acrylic rubber and a polyolefin-based plastic film, and protects a roughened coated plate. It is an extremely useful primer composition as a primer for producing a film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyohisa Ota 1500 Ogawa, Shimodate, Ibaraki Prefecture Shimodate Laboratory, Hitachi Chemical Co., Ltd. (56) Reference JP-A-58-32661 (JP, A) JP Sho 59-53557 (JP, A)

Claims (2)

(57) [Claims] (1) A chlorine content of 1 to 10% by weight of a functional group consisting of a hydroxyl group or a carboxyl group in a molecule is added.
For 100 parts by weight of a composition comprising 0 to 40% by weight of chlorinated polyolefin 10 to 90% by weight and (2) 90 to 10% by weight of an acrylic rubber containing a hydroxyl group or a carboxyl group in the molecule, (3) the above hydroxyl group Alternatively, an undercoat composition for an adhesive film, which comprises 1 to 20 parts by weight of an isocyanate reaction catalyst that accelerates the reaction between a carboxyl group and an isocyanate group. 2. The primer composition for pressure-sensitive adhesive films according to claim 1, wherein the isocyanate reaction catalyst is dibutyltin dilaurate.