JPH04370179A - Application sheet having undercoating layer - Google Patents

Abstract

PURPOSE:To provide a tacky sheet of a polyolefinic plastic film substrate, excellent in adhesion and having hardly any change in tack characteristics with time. CONSTITUTION:A tacky sheet is obtained by forming an undercoating layer composed of the first layer composed of (a) a crosslinked chlorinated polyolefin or (b) a crosslinked acrylic acid-based polymer and the second layer composed of ethylene vinyl acetate copolymer on the surface of a polyolefinic plastic film substrate and further providing a tacky agent layer composed of polyisobutylene or butyl rubber thereon.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive sheet, film or tape having a polyolefin plastic film as a support.

0002

[Prior Art] Of the rubbers used as adhesives for adhesive sheets, films, or tapes (hereinafter referred to as adhesive sheets) for surface protection of metal plates, painted steel plates, resin plates, etc., natural rubber, polyisoprene, or polybutadiene are used. Since diene rubber has unsaturated double bonds in its molecules, it is susceptible to oxidative deterioration and has low weather resistance and heat resistance. On the other hand, acrylic rubber, which has excellent weather resistance, is chemically active and highly reactive, so it interacts strongly with the adherend, and sometimes forms chemical bonds with the adherend surface. The disadvantage is that the adhesive strength changes significantly over time, and in severe cases, it may become impossible to peel or a portion of the adhesive may transfer to the surface of the adherend.

On the other hand, polyisobutylene or butyl rubber is chemically extremely inert due to its molecular structure, has low reactivity, and has low polarity. Therefore, it has superior weather resistance when compared to the above-mentioned diene rubber, has no drawbacks like acrylic rubber, and maintains useful performance as a pressure-sensitive adhesive for pressure-sensitive adhesive films. However, due to the above-mentioned properties, the adhesion to the polyolefin plastic film used as a support is low, and direct coating is not sufficient as an adhesive film. As a method for improving adhesion, Japanese Patent Laid-Open No. 56-59885 proposes an undercoat composition comprising chlorinated polypropylene and butyl rubber.

0004

[Problems to be Solved by the Invention] Adhesive sheets using this primer composition have no problems in applications where the pasting period is short or only light processing is performed, but the pasting period is one month. The main component is polyisobutylene or butyl rubber for materials that exceed the maximum pressure, are subjected to tight bending or deep drawing, are stored as rolls after pasting such as painted steel plates, and are subjected to high pressure, or for outdoor applications such as building materials. The adhesion between the adhesive and the support was insufficient, and the adhesive often transferred to the surface of the adherend, which was a problem.

[0005]

[Means for Solving the Problems] As mentioned above, the present inventors have developed a method using a pressure-sensitive adhesive mainly composed of a polymer having isobutylene units as a main component, which is useful as a pressure-sensitive adhesive sheet, and a support made of a polyolefin plastic film. As a result of intensive experiments and research in order to provide a primer with excellent adhesion, the present invention has been completed.

That is, the present invention provides an adhesive sheet using a polyolefin plastic film as a support and polyisobutylene or butyl rubber as an adhesive, in which the surface of the support is made of (a) a crosslinked chlorinated polyolefin or (b) It is characterized by having an undercoat layer composed of a first layer made of a crosslinked acrylic acid polymer and a second layer made of an ethylene vinyl acetate copolymer formed thereon. The crosslinked chlorinated polyolefin or crosslinked acrylic acid polymer as used in the present invention refers to a basic polyolefin or acrylic acid polymer having a crosslinkable functional group that is crosslinked with a crosslinking agent.

Examples of chlorinated polyolefins having functional groups include chlorinated polyethylene and chlorinated polypropylene, and examples of functional groups include hydroxyl groups, carboxyl groups, and amino groups. Here, if the content of functional groups added to the chlorinated polyolefin is less than 0.1% by weight, the adhesion with the support will decrease, and if it exceeds 20% by weight, ethylene vinyl acetate copolymer or functional groups will be added. The adhesion between the ethylene-vinyl acetate copolymer and the crosslinking agent or a mixture of both is reduced.

Chlorinated polyolefin chlorine content is 10~
50% by weight, preferably 20-30% by weight. 10
If it is less than 50% by weight, the solubility in the solvent will be insufficient and workability will be poor, and if it exceeds 50% by weight, the adhesion to the support will be poor.

[0009] Examples of acrylic acid polymers include polymers obtained by copolymerizing an alkyl acrylate monomer, an alkyl methacrylate monomer, and a monomer having a functional group. The alkyl acrylate monomer and alkyl methacrylate monomer preferably have an alkyl group having 1 to 8 carbon atoms. Such monomers include methyl acrylate,
Examples include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and ethyl methacrylate.

Monomers to be copolymerized with these include those having a hydroxyl group, carboxyl group, epoxy group, amino group, etc. as functional groups, specifically 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, methacrylic acid. 2-hydroxyethyl, 2-hydroxypropyl methacrylate, acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, glycidyl acrylate, acrylamide, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, t-butylaminoethyl methacrylate Examples include.

[0011] A suitable amount of a vinyl monomer copolymerizable with the above-mentioned alkyl acrylate monomer and alkyl methacrylate monomer, such as styrene, vinyl acetate, acrylonitrile, methacrylonitrile, etc., can be used.

The amount of functional groups in the acrylic acid polymer is 0.1 to 50, preferably 1 to 50% by weight of the monomer having functional groups.
It is 5. If it is less than 0.1% by weight, thermal curing will be insufficient, and if it is more than 50% by weight, crosslinking will proceed too much, and in both cases the adhesiveness between the adhesive and the support will be reduced.

Next, examples of the crosslinking agent include those commonly used, such as polyfunctional isocyanates, amino resins, amines, and epoxy resins, which promote thermal curing by chemical reaction with the above-mentioned functional groups. Particularly desirable are polyfunctional isocyanates and amino resins that react rapidly at relatively low temperatures. The polyfunctional isocyanates mentioned here include tolylene diisocyanate, diphenylmethane diisocyanate, 1,
5-naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, triphenylmethane triisocyanate, polyphenylmethane polyisocyanate, etc., and various derivatives such as trimethylolpropane adduct of tolylene diisocyanate and biuret form of hexamethylene diisocyanate. Can be mentioned.

Next, amino resins include melamine, benzoguanamine, urea, etc., added and condensed with formaldehyde or alcohol, such as methylolmelamine, methylated methylolmelamine, butylated butyrolmelamine,
Examples include methylolbenzoguanamine and methylolurea.

The amount of the crosslinking agent is 0.1 to 100 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymer. If it is less than 0.1 part by weight, thermal curing will be insufficient, and if it is more than 100 parts by weight, crosslinking will progress too much, resulting in poor adhesion between the adhesive and the support.

Next, the ethylene vinyl acetate copolymer used for the second layer may be uncrosslinked or crosslinked.

The ethylene-vinyl acetate copolymer is a polymer obtained by copolymerizing ethylene and vinyl acetate, and has a vinyl acetate content of 5 to 50% by weight, preferably 10 to 30% by weight. If it is less than 5% by weight, the adhesion with the first layer is insufficient, and if it is more than 50% by weight, the adhesion with the adhesive is insufficient and it cannot be used.

[0018] Ethylene-vinyl acetate copolymers having functional groups capable of crosslinking can also be obtained by introducing hydroxyl groups, carboxyl groups, acetoxyl groups, etc. into the ethylene-vinyl acetate copolymers described above using saponification, grafting, or modification reactions. This is what I did. Examples of this crosslinking agent include the aforementioned polyfunctional isocyanates and amines.

The support to which the primer of the present invention can be applied is a homopolymer of α-olefin having 2 to 6 carbon atoms such as ethylene, propylene, butene, pentene, methylpentene, etc., ie, polyethylene, polypropylene, polybutene, polymethylpentene, etc. Or a copolymer or mixture of these α-olefins, or a copolymer containing these α-olefins as a main component and other polymerizable α,β-unsaturated monomers. Note that before applying the primer to the surface of these supports, the coated surface may be modified by corona treatment, flame treatment, or the like. The above primer is diluted with a suitable solvent and applied to the surface of the support to a thickness of 1 to 5 microns.

The adhesive to which the undercoat according to the present invention can be applied is one containing polyisobutylene or butyl rubber as a main component. Here, polyisobutylene is an isobutylene polymer, a copolymer of isobutylene, normal butylene,
Butyl rubber is a copolymer of isobutylene and isoprene (
(regular butyl rubber, chlorinated butyl rubber, brominated butyl rubber), or partially vulcanized products and modified products thereof.

[0021]

[Function] The present invention divides the undercoat into two layers, each having good bonding strength to the polyisobutylene or butyl rubber that is the main component of the adhesive and the polyolefin plastic film that is the support, and By providing good bonding strength between the agents, the adhesion between polyisobutylene or butyl rubber and polyolefin plastic film, which has been difficult in the past, can be significantly improved.

[0022]

[Examples] The present invention will be explained below with reference to Examples, but the present invention is not limited by the Examples. All parts are by weight.

Example 1 Hydroxyl group-added chlorinated polypropylene S-180 (manufactured by Sanyo Kokusaku Pulp Co., Ltd., hydroxyl group content 1.7%, chlorine content 22%) and Coronate L were mixed into S-180/Coronate L. A primer A solution, which is a 1% toluene solution, was prepared at a ratio of = 100 parts/5 parts. The obtained solution was coated on the corona-treated surface of a polyethylene film (thickness: 60 μm), which had undergone corona treatment on one side, to a solid content of 0.2 g/m 2 and dried at 100° C. for 1 minute. Next, use EV as primer B.
550 (manufactured by Mitsui Polychemical Co., Ltd.) in 1% toluene (50°C), 0.2 g of solid content was applied to the coated surface of Primer A.
/m2 and dried at 100°C for 1 minute. Furthermore, polyisobutylene MML-120 (
A 5% toluene solution (manufactured by Tonex Co., Ltd.) was applied to give a solid content of 10 g/m 2 and dried at 100° C. for 2 minutes to produce an adhesive film.

Example 2 In Example 1, HPR VR10 was used as primer B.
3 (manufactured by Mitsui Polychemical Co., Ltd.) and Coronate L are V
An adhesive film was produced in the same manner except that a 1% toluene solution having a ratio of R103/Coronate L=100 parts/10 parts was used.

Example 3 In Example 1, Evaflex 55 was used as the primer B.
0 and HPR VR103 and Coronate L are Evaflex 550/VR103/Coronate L=50 parts/
An adhesive film was produced in the same manner except that a 1% toluene solution having a ratio of 50 parts/5 parts was used.

Comparative Example 1 An adhesive film was produced in the same manner as in Example 1, except that the primer A was not applied.

Comparative Example 2 An adhesive film was produced in the same manner as in Example 1, except that the primer B was not applied.

Example 4 Butyl acrylate, acrylonitrile and acrylic acid 2
- Hydroxyethyl, butyl acrylate/acrylonitrile/2-hydroxyethyl acrylate = 85 parts/1
After pearl polymerization (initiator: hydrogen peroxide, emulsifier: nonionic anionic surfactant, reaction temperature: 65°C, polymerization time: 5 hours) with a ratio of 0 parts/5 parts, the acrylic polymer was washed with water and dried. Obtained. Next, the obtained acrylic polymer was made into a 1% toluene solution, and 3 parts of Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) was added to this solution based on 100 parts of the solid content of the acrylic polymer to prepare a primer A solution. The resulting solution was applied to a polyethylene film (thickness: 60 mm) with corona treatment on one side.
It was coated on the corona-treated surface of a 1000 µm (1.5 µm) corona-treated surface at a solid content of 0.2 g/m 2 and dried at 100° C. for 1 minute. Next, as primer B, a 1% toluene solution (50°C) of EV550 (manufactured by Mitsui Polychemical Co., Ltd.) was applied to the coated surface of primer A so that the solid content was 0.2 g/m2. 1 in °C
Dry for a minute. Furthermore, polyisobutylene M is applied to the coated surface.
A 5% toluene solution of ML-120 (manufactured by Tonex Co., Ltd.) was applied to a solid content of 10 g/m2.
It was dried at ℃ for 2 minutes to produce an adhesive film.

Example 5 In Example 4, HPR VR10 was used as primer B.
3 (manufactured by Mitsui Polychemical Co., Ltd.) and Coronate L, V
An adhesive film was produced in the same manner except that a 1% toluene solution having a ratio of R103/Coronate L=100 parts/10 parts was used.

Example 6 In Example 4, Evaflex 55 was used as the primer B.
0 and HPR VR103 and Coronate L, Evaflex 550/VR103/Coronate L = 50 parts/
An adhesive film was produced in the same manner except that a 1% toluene solution having a ratio of 50 parts/5 parts was used.

Comparative Example 3 An adhesive film was produced in the same manner as in Example 4, except that the primer A was not applied.

Comparative Example 4 An adhesive film was prepared in the same manner as in Example 4, except that the primer B was not applied.

Comparative Example 5 An adhesive film was produced in the same manner as in Example 4, except that acrylic polymer alone was used as the undercoat A.

Tables 1 and 2 show the test results for the above adhesive films.

[0035]

[Table 1]

[0036]

[Table 2]

Test details *1 Adhesion between adhesive and support Roll pressure bonding of adhesive sides of adhesive film (2 kgf/
cm), treated under heating and pressure conditions of 65°C and 30 kg/cm2 for 1 day, and then left at room temperature for 1 hour.
A peel test was conducted at a speed of 180° at a speed of 180° to measure the peeling resistance between the adhesive and the support. *2 Roll pressure bonding of heat-resistant adhesive film to aluminum plate (2 kgf/cm
) and treated under heating and pressure conditions of 65° C. and 30 kg/cm 2 for one day, and then left at room temperature for 1 hour, the adhesive film was peeled off, and the surface of the aluminum plate was observed. *3 Roll pressure bonding of weather-resistant adhesive film to aluminum plate (2 kgf/cm
) and using a sunshine weather meter (manufactured by Suga Test Instruments Co., Ltd., model WEL-SUN-HC), the atmospheric conditions:
After being treated at 43° C.-60% RH (black panel temperature: 63° C., rainfall: 12 min/h) for 200 hours and left at room temperature for 1 hour, the adhesive film was peeled off and the surface of the aluminum plate was observed. ○: No adhesive transfer was observed. ×: Transfer of adhesive is observed. The results are shown with the symbols above.

[0038]

[Effect of the invention] According to the present invention, adhesion, heat resistance,
It is possible to provide pressure-sensitive adhesive sheets that exhibit little change over time, such as weather resistance, and have great industrial value.

Claims (1)

[Claims] 1. An adhesive sheet having a polyolefin plastic film as a support and polyisobutylene or butyl rubber as an adhesive, wherein the surface of the support is made of (a) a crosslinked chlorinated polyolefin or (b)
A pressure-sensitive adhesive sheet having an undercoat layer comprising a first layer made of a crosslinked acrylic acid polymer and a second layer made of an ethylene vinyl acetate copolymer formed thereon.