JPH0931426A - Adhesive sheet for automobile coating film protection - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To prevent deformation of a paint film applied to a car body of an automobile and to protect the paint film of a car body from acid rain, dust, dust, etc. A pressure-sensitive adhesive sheet for protecting an automobile coating film, which has a sufficient adhesive force and does not leave an adhesive residue on the vehicle body when peeled off. SOLUTION: The automobile coating film protection is characterized in that a support is provided with an adhesive layer having a rubber-based adhesive having a penetration of 100 to 250 according to JIS-K-2207 at 25 ° C. It is an adhesive sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive film for protecting automobile coating film, which is difficult to deform the coating film applied to the automobile body and is suitable for protecting the coating film of automobile body from acid rain, dust, dust and the like. It is about the seat.

[0002]

2. Description of the Related Art Adhesive sheets have been widely used for commercial use, office use, process control, physical distribution control, household use, etc. in the form of labels, stickers, patches, delivery slips and the like. Explaining the general configuration of this pressure-sensitive adhesive sheet, it is a state in which the pressure-sensitive adhesive is sandwiched between the surface substrate and the release sheet, the surface substrate is paper, foil,
Alternatively, a film or the like is used. Further, as the release sheet, high density base paper such as glassine paper, clay coated paper, polyamid base paper obtained by laminating a resin film such as polyethylene on kraft paper or high quality paper, or polyvinyl alcohol, starch on kraft paper or high quality paper, etc. A resin-coated base paper having a coating layer containing a water-soluble polymer or the like and a pigment as a main component and coated with a release agent such as a silicone compound or a fluorine compound is used. As the pressure-sensitive adhesive, various acrylic, rubber-based, vinyl ether-based emulsions, solvent or solventless pressure-sensitive adhesives are used.

On the other hand, various floating substances such as dust, acid rain, etc. and collisions when a newly painted automobile or its parts are loaded on a ship or truck and transferred to a remote place such as overseas There is a demand for means for preventing damage, gloss blurring, discoloration, etc. of a coating film caused by an object. Conventionally, a method of providing a wax coating film having a thickness of 5 to 20 μm has been known as such a preventive measure. However, it is difficult to provide a uniform wax coating film, a uniform protective film cannot be obtained, it is susceptible to acid rain, it easily stains, it penetrates into the coating film and causes discoloration, etc. There is a problem in that a great deal of labor is required for coating and its removal, and that environmental problems such as the use of solvents and the treatment of waste liquid are likely to occur.

Therefore, various surface-protective pressure-sensitive adhesive sheets having a pressure-sensitive adhesive layer provided on a support have been investigated (Japanese Patent Laid-Open Nos. 56-55251 and 57-205470). There is a problem that the adhesive strength of the adhesive layer to be applied to the coating film is low, and the basic performance such as peeling off of the adhesive sheet for surface protection when the vehicle is transported outdoors cannot be satisfied.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides an excellent automotive paint film protective film which is difficult to deform a paint film applied to a car body and is suitable for protecting the car body film from acid rain, dust, dust and the like. Regarding an adhesive sheet, it is intended to provide an adhesive sheet for protecting an automobile coating film, which has a sufficient adhesive force to a vehicle body and does not leave a glue on the vehicle body when peeled off.

[0006]

The present invention has a penetration of 100 to 2 according to JIS-K-2207 at 25 ° C.
A pressure-sensitive adhesive sheet for protecting an automobile coating film, comprising a support and a pressure-sensitive adhesive layer having a rubber pressure-sensitive adhesive of 50.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure-sensitive adhesive used in the pressure-sensitive adhesive sheet for protecting automobile coating film according to the present invention has a JI of
It is necessary that the rubber-based pressure-sensitive adhesive has a penetration degree of 100 to 250 based on SK-2207, and examples thereof include natural rubber, polyisobutylene, isobutylene-isoprene copolymer, and isobutylene-1-butene copolymer. Polymers, isobutylene-n-butene copolymers and other rubber-based polymers as a main component, tackifiers, softeners, fillers, release agents, pigments, in order to obtain a predetermined penetration as necessary. An ultraviolet absorber or the like is appropriately added. Among them, a pressure-sensitive adhesive using a polyisobutylene, an isobutylene-1-butene copolymer, or an isobutylene-n-butene copolymer is preferable because it is less likely to be thermally deteriorated when exposed to sunlight outdoors. Incidentally, if the penetration of the adhesive exceeds 250, the adhesive becomes too soft and has a high adhesive force to the automobile coating film, which makes it difficult to peel off the adhesive sheet. Conversely, the penetration is 1
If it is less than 00, the pressure-sensitive adhesive becomes too hard and sufficient adhesive performance cannot be obtained. The preferable penetration is in the range of 120 to 220.

Examples of the support which constitutes the pressure-sensitive adhesive sheet of the present invention include cellophane, soft polyvinyl chloride, hard polyvinyl chloride, polyethylene terephthalate, homopolymers and copolymers of α-olefins such as ethylene, propylene and butene. Furthermore, films such as those obtained by copolymerizing monomers such as vinyl acetate and methyl methacrylate,
Examples include sheets such as metal foil, non-woven fabric, and synthetic paper.

The pressure-sensitive adhesive sheet for protecting automobile coating film is often exposed to the sun's rays outdoors. When the support is a white film, it reflects the sun's rays and suppresses the temperature rise of the coating film. This makes it possible to prevent thermal deterioration of the pressure-sensitive adhesive, which is preferable. In particular, for homopolymers and copolymers of α-olefins, titanium oxide, zinc oxide, lithopone, lead white,
Chalk, barium sulfate, alumina white, silica white, and clay are more preferably applied or contained with titanium oxide or zinc oxide. Among them, the support is 2
The light transmittance at 00 to 400 nm is preferably 5% or less. By the way, when the light transmittance of wavelength 200-400 nm exceeds 5%, the adhesive component migrates to the automobile coating film,
It is not preferable because the protective property of the automobile coating film and the weather resistance of the pressure-sensitive adhesive are deteriorated such that the coating film becomes cloudy or discolored.

Further, when a primer layer made of a resin whose main component is an acrylic acid ester copolymer modified with an alkyleneimine compound is provided on the back surface of the support, the adhesion between the support and the pressure-sensitive adhesive is improved, and the pressure-sensitive adhesive component is It is desirable because it effectively suppresses the occurrence of fogging in the coating film by shifting to the automobile coating film.

Incidentally, the acrylic acid ester copolymer modified with the alkyleneimine compound used in the present invention includes (meth) acrylic acid, cinnamic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid and monoalkylmalein. A monomer containing one or more kinds of carboxyl groups selected from acids, monoalkyl itaconic acid, monoalkyl fumaric acid and the like, and (meth) acrylamide, N-methylol (meth) acrylamide, 2-hydroxypropyl ( (Meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) Acrylate,
From 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylonitrile, styrene, α-methylstyrene, vinyl acetate, (meth) acrolein, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, etc. A copolymer obtained by copolymerizing one or more selected monomers is ethyleneimine, butyleneimine, N-
(2-aminoethyl) aziridine, N- (3-aminopropyl) aziridine, N- (2-aminopropyl) propyleneimine and the like are reacted.

The method for producing the copolymer used as the main component of the primer layer is not particularly limited, and includes solution polymerization method, bulk polymerization method, emulsion polymerization method,
A polymerization method such as a suspension polymerization method can be appropriately adopted.

The monomer concentration during polymerization is usually 20 to
70% by weight, preferably about 30 to 60% by weight is suitable. Examples of the polymerization initiator used during the polymerization include persulfates such as potassium persulfate and ammonium persulfate, 2,2′-azobisisobutyronitrile, 2,2 ′.
-Azo compounds such as azobis (2,4-dimethylvaleronitrile), hydrogen peroxide, benzoyl peroxide,
Peroxides such as di-t-butyl peroxide, lauryl peroxide, ammonium persulfate and sodium sulfite,
Examples thereof include so-called redox type polymerization initiators which are combined with acidic sodium sulfite and the like. The amount of the above-mentioned polymerization initiator used is usually 0.
It is desirable that the amount is 2 to 2% by weight, and more preferably about 0.3 to 1% by weight.

Further, as a chain transfer agent to be added upon polymerization, alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, dodecyl mercaptan, octyl thioglycolate, nonyl thioglycolate, 2-ethylhexyl thioglycolate, thioglycolic acid esters such as β-mercaptopropionate-2-ethylhexyl, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-
Isopropylidene-1-cyclohexene and the like can be mentioned. Particularly, thioglycolic acid esters, 2,4
When -diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene or the like is used, the resulting copolymer has a low odor, which is preferable.

The amount of the chain transfer agent used is adjusted in the range of 0.001 to 3% by weight based on the total monomers to be polymerized.
The polymerization reaction is usually at room temperature to 200 ° C., preferably 40 to 1
It is carried out under a temperature condition of 20 ° C. for about 2 to 8 hours. Further, the amination reaction with the alkyleneimine compound can be obtained, for example, by mixing and stirring the copolymer and the alkyleneimine under a temperature condition of 40 to 150 ° C, preferably 50 to 100 ° C. Further, a thickener, a wetting agent, a leveling agent, a defoaming agent, a cross-linking agent, a pigment and the like may be appropriately added to the copolymer for the primer layer.

The method of applying or impregnating the coating liquid for the primer layer onto the support is, for example, air knife coater, roll coater, gravure coater, bar coater, blade coater, rod blade coater, lip coater, curtain coater, and various types of coaters. Equipment such as a size press coater is used. The coating amount of the primer layer is 0.1 to 20 g / m ^{2 as} a dry weight, and more preferably 0.1.
It is adjusted in the range of 5 to 10 g / m ² .

Regarding the method for constructing the pressure-sensitive adhesive sheet for protecting automobile coating film of the present invention, the method of directly applying the pressure-sensitive adhesive coating liquid or the heat-melting liquid of the pressure-sensitive adhesive to the support or the surface of the release agent of the release sheet according to a conventional method. A pressure-sensitive adhesive is applied on the top and dried if necessary to provide a pressure-sensitive adhesive layer, and this pressure-sensitive adhesive layer and the back surface of the support or the surface of the primer layer provided on the back surface of the support are laminated to finish. As the device for applying the adhesive, for example, a reverse roll coater, a knife coater, a bar coater, a die coater, a gear-in die coater, a slot die coater, an air knife coater, a reverse gravure coater, a variogravure coater, etc. are appropriately used. It The amount of adhesive applied is 5 to 30 g / m on a dry basis.
² , more preferably in the range of 7 to ²⁰ g / m ² . Incidentally, if it is less than 5 g / m ² , the adhesive performance of the obtained pressure-sensitive adhesive sheet will be insufficient, while if it exceeds 30 g / m ² , the pressure-sensitive adhesive may squeeze out or cause cohesive failure during peeling.

The pressure-sensitive adhesive sheet for protecting automobile coating film of the present invention comprises
A release sheet may be attached to the surface of the pressure-sensitive adhesive layer, or the following release agent layer may be provided on the surface of the support opposite to the pressure-sensitive adhesive layer. The base material when using the release sheet, high-density base paper such as glassine paper, clay-coated paper, kraft paper or high-quality paper, such as casein, dextrin, starch, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, polyvinyl Natural such as alcohol, styrene-butadiene copolymer, methylmethacrylate-butadiene copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, acrylic ester copolymer,
Alternatively, a release substrate provided with a sealing layer mainly composed of a synthetic resin and a pigment, or polylaminated paper obtained by laminating polyethylene or the like on kraft paper or high-quality paper, or polypropylene, water on a film such as polyethylene terephthalate, or the like, 0.05% dry weight of solvent type or non-solvent type silicone resin, fluororesin, long chain alkyl compound, etc.
A release agent layer formed by thermal curing, ionizing radiation curing or the like after coating of about 3 g / m ² is used. When the release agent layer is directly provided on the support and the adhesion between the support and the release agent is poor, it is desirable to subject the release agent application surface to a surface activation treatment such as corona discharge treatment.

[0019]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. Unless otherwise specified, all parts, weights, ratios, coating amounts and the like in the examples are shown by solid content weight.

Example 1 Polypropylene / polyethylene mixed resin (weight ratio: 9 /
A 50 μm-thick film consisting of 1) is subjected to corona discharge treatment on one surface, and a long-chain alkyl release agent is applied with a bar coater to a dry weight of 0.1 g / m ^2, and the release agent is dried. Layers were formed. Then, polyisobutylene (trade name: Tetrax 3T, manufactured by Nippon Petrochemical Co., Ltd.) was applied as an adhesive on the opposite side of the release agent layer of the film with a knife coater so that the dry weight was 15 g / m ² . After drying, the pressure-sensitive adhesive sheet for protecting automobile coating film of the present invention was obtained.

Example 2 In the same manner as in Example 1 except that polyisobutylene (trade name: Tetrax 4T, manufactured by Nippon Petrochemical Co., Ltd.) was used as the adhesive, the automobile coating film protection of the present invention. An adhesive sheet for use was obtained.

Example 3 In the same manner as in Example 1 except that polyisobutylene (trade name: Tetrax 6T, manufactured by Nippon Petrochemical Co., Ltd.) was used as the adhesive, the automobile coating film protection of the present invention. An adhesive sheet for use was obtained.

Example 4 [Production of support] Polypropylene 70% by weight Polyethylene 10% by weight Titanium oxide 19.5% by weight Ultraviolet absorber (trade name: Tinuvin 326, manufactured by Ciba-Geigy) 0.5% by weight The resin mixture is supplied to an extruder, melt-kneaded by the extruder, and extruded in a film form from a T die to give a thickness of 40
A white film of μm was produced.

"Production of Adhesive Sheet" The surface of the above-mentioned support was subjected to corona discharge treatment, and a long-chain alkyl release agent was applied with a bar coater to a dry weight of 0.1 g / m ² .
The release agent layer was formed by drying. On the other hand, the back surface of the support was subjected to corona discharge treatment, and polyisobutylene (trade name: Tetrax 5T, manufactured by Nippon Petrochemical Co., Ltd.) was applied as an adhesive with a reverse roll coater to a dry weight of 12 g / m ^2. After drying, the pressure-sensitive adhesive sheet for protecting automobile coating film of the present invention was obtained.

Example 5 [Production of support] Polypropylene 74% by weight Polyethylene 10% by weight Zinc oxide 15.5% by weight Light stabilizer (trade name: Tinuvin 622LD, manufactured by Ciba-Geigy) 0.5% by weight The resin mixture is supplied to an extruder, melt-kneaded by the extruder, and extruded in a film form from a T-die to a thickness of 50.
A white film of μm was produced.

[Production of Adhesive Sheet] The surface of the above support was subjected to corona discharge treatment, and a long-chain alkyl release agent was applied by a bar coater to a dry weight of 0.1 g / m ² .
The release agent layer was formed by drying. On the other hand, the back surface of the support was subjected to corona discharge treatment and modified with an alkyleneimine compound to obtain an acrylate copolymer (trade name: Polyment N
K-350, manufactured by Nippon Shokubai Co., Ltd.) has a dry weight of 1.5.
It is coated with a bar coater so as to be g / m ² and dried, and polyisobutylene (trade name: Tetrax 3T, manufactured by Nippon Petrochemical Co., Ltd.) as an adhesive has a dry weight of 15 g.
It was coated with a knife coater so as to be / m ² and dried to obtain an automobile coating film-protecting pressure-sensitive adhesive sheet of the present invention.

Example 6 [Production of coating liquid for primer layer] A resin was synthesized by the following formulation in a four-necked flask equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas introduction tube. Isopropyl alcohol: 21 parts Toluene: 49 parts Methacrylic acid: 2.4 parts Methyl methacrylate: 27.6 parts The above composition was charged into a flask and heated to 80 ° C. while blowing nitrogen gas. 0.14 parts of azobisbutyronitrile and 7.5 while keeping the liquid temperature at 80 ° C.
Add in several batches over time, 80 ° C after final addition
Then, it was held for another hour. And it cooled to room temperature and obtained the solution of the copolymer containing a carboxyl group. Then, add 1.3 parts of ethyleneimine to the flask above.
Dropped in minutes. After 1 hour from the completion of the dropping, the temperature was raised to 75 ° C., and the temperature was kept at the same temperature for 4 hours. Then, the distillation apparatus was set in a 4-neck flask and heated under reduced pressure to remove isopropyl alcohol and unreacted ethyleneimine. After removal to the outside of the system, an acrylate copolymer modified with an alkyleneimine compound was obtained. Finally, the nonvolatile content was adjusted to 10% with toluene to obtain a primer layer coating liquid.

An automobile coating film-protecting pressure-sensitive adhesive sheet of the present invention was produced in the same manner as in Example 5, except that the coating liquid for a primer layer was applied in an amount of ² g / m ² .

Comparative Example 1 In Example 1, a dry weight of a pressure-sensitive adhesive containing polyisobutylene as a main component and having a penetration of 80 according to JIS-K-2207 at 25 ° C. of 12 was applied to the back surface of the front substrate.
coated with a reverse roll coater to achieve g / m ² ,
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that it was dried.

COMPARATIVE EXAMPLE 2 In Example 1, the dry weight of the pressure-sensitive adhesive mainly composed of polyisobutylene having a penetration of 330 according to JIS-K-2207 at 25 ° C. on the back surface of the front substrate was 1
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that coating was carried out with a reverse roll coater so as to obtain 5 g / m ² and drying.

The eight types of pressure-sensitive adhesive sheets thus obtained were evaluated as follows, and the obtained results are shown in Table 1.

[Adhesive Strength] A protective pressure-sensitive adhesive sheet was adhered to a metal plate having an alkyd / melamine coating film at room temperature, and JI
According to S-Z-0237, the load (g / 25 mm) when peeling at an angle of 180 ° at a pulling speed of 300 mm / min was measured by an Instron type tensile tester.

[Glue Remaining] After sticking a protective pressure-sensitive adhesive sheet at room temperature on a metal plate having an alkyd / melamine coating film,
After leaving it under the condition of 80 ° C. for 24 hours, the adhesive residue on the coating film surface was visually evaluated when the protective pressure-sensitive adhesive sheet was peeled off at room temperature. ⊚: No adhesive residue at all ○: Almost no adhesive residue at Δ: Some adhesive residue, but no problem in practical use ×: Severe adhesive residue, not practical

[Penetration] According to JIS-K-2207, the penetration was measured with a penetration tester under the conditions of 25 ° C. and a weight of 150 g. [Light transmittance] Light transmittance at a wavelength of 200 to 400 nm was measured by a spectrophotometer according to JIS-K-7105.

[Applicability of Coating Film Adhesion] After adhering the protective pressure-sensitive adhesive sheet to the plate having the alkyd / melamine coating film at room temperature, the protective pressure-sensitive adhesive sheet was left standing outdoors for 3 months and the floating state of the protective pressure-sensitive adhesive sheet was visually judged. ◎: There is no uplifting ○: Almost no uplifting △: There is some uplifting, but there is no problem in practical use ×: There is considerable uplifting, which is a problematic point in practical use

[Comprehensive Evaluation] The respective evaluations were comprehensively evaluated to determine the performance as the pressure-sensitive adhesive sheet for protecting automobile coating film of the present invention. ⊚: Very good performance ◯: Excellent performance Δ: Slightly insufficient, but at a level where there is no practical problem ×: Insufficient, practical problem level

[0037]

[Table 1]

[0038]

As is apparent from the examples, the pressure-sensitive adhesive sheet for protecting automobile coating film obtained according to the present invention has a sufficient adhesive force to the vehicle body and has a glue remaining on the vehicle body when peeled off. It was a pressure-sensitive adhesive sheet for protecting automobile coating films.

Claims (4)

[Claims] 1. An automobile coating film protective film characterized in that a support is provided with an adhesive layer having a rubber-based adhesive having a penetration of 100 to 250 according to JIS-K-2207 at 25 ° C. Adhesive sheet. 2. The pressure-sensitive adhesive sheet for protecting automobile coating film according to claim 1, wherein the support is a polyolefin resin film containing titanium oxide or zinc oxide. 3. The pressure-sensitive adhesive sheet for protecting an automobile coating film according to claim 1, wherein the support has a light transmittance of 200 to 400 nm of 5% or less. 4. The support is a polyolefin resin film, and a primer layer containing an acrylic acid ester copolymer modified with an alkyleneimine compound as a main component is provided between the support and the adhesive layer. The pressure-sensitive adhesive sheet for protecting automobile coating film according to any one of 1 to 3.