JPH10140108A - Pressure-sensitive adhesive sheet for protecting coating film of automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pressure-sensitive adhesive sheet for protecting the coating film of an automobile from stains and external damages. SOLUTION: This sheet is prepared by using a polyolefin resin as the base film, forming a pressure-sensitive adhesive layer on one surface of the base film and forming a release agent layer on the other surface In this sheet, the release agent layer comprises a release agent and 0.1-2 pts.wt., per 100 pts.wt. release agent, weathering improver, and the pressure-sensitive adhesive layer comprises a rubber-based pressure-sensitive adhesive. The sheet should have a transmittance of 1% or below to light at a wavelength of 295-400nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive sheet for protecting a paint film of an automobile for the purpose of preventing the paint film applied to the automobile from being stained or damaged.

[0002]

2. Description of the Related Art Conventionally, a painted new vehicle or a part thereof is loaded on a truck or ship and transported to a remote place such as an overseas location, or temporarily temporarily indoors or outdoors until the new vehicle reaches a user's hand. When stored (2 to 12 months), various suspended or colliding substances such as acid rain, dust, and dust may cause damage to the paint film, fogging, gloss blur, and discoloration. Have been. As such means, spray coating such as paraffin wax has a thickness of 5 to 5.
A method of providing a protective film of 20 μm has been known. However, the thickness of the wax coating film tends to vary and easily affect the protection performance. Further, since the wax is a main component, the protection performance is deteriorated due to oxidative deterioration due to sunlight, and the wax itself is applied to the coating film. However, there is a problem that the color is discolored due to penetration. In addition, the work of painting and removing the wax requires a great deal of work, and the use of a solvent as a remover requires a wastewater treatment facility, so that there are many problems from the working environment.

Therefore, recently, a method of protecting a paint film of an automobile by using an adhesive paint film for protecting the paint film in place of the wax (for example, JP-A-6-73352, JP-A-6-73352).
No. 128540) has been adopted.
In general, a film for protecting an automobile coating film is processed into a tape shape so that it can be easily bonded to a completed automobile body.

It is important that the pressure-sensitive adhesive sheet for protecting a paint film has excellent lapping properties without peeling off while being adhered to an adherend (automobile body) during transportation and temporary storage of the vehicle. Furthermore, it is desirable that the adherend can be easily peeled off when it becomes unnecessary, and that the adherend has no adhesive residue after the peeling and does not contaminate the adherend. However, in general, even when the pressure-sensitive adhesive sheet for protecting the coating film has an appropriate adhesive force immediately after being applied, the adhesive force increases with time, and it becomes difficult to peel the pressure-sensitive adhesive sheet for protecting the coating film from the adherend surface. In some cases, when peeled as it is, there is a problem that glue remains or a base film is broken.

[0005] In particular, after the adhesive film for protecting a paint film is attached to an adherend, the film surface is directly exposed to sunlight when temporarily stored outdoors (2 to 12 months) or when transported. If present, in addition to being placed in a high temperature state of 50 to 80 ° C., and exposed to severe conditions such as exposure to a lot of ultraviolet rays, the tendency of adhesive residue and substrate film breakage due to deterioration of the base film and the adhesive is remarkable. become.

[0006] In order to solve the above-mentioned problems, it is possible to improve the weather resistance by mixing a known ultraviolet absorber, a light stabilizer, an antioxidant and other weather resistance improvers into a base film or an adhesive. Method (for example, JP-A-7-216325)
Is adopted. However, such a method can improve the weather resistance of the base film and the pressure-sensitive adhesive, and can suppress the deterioration due to ultraviolet rays and heat to some extent, but the amount of the weather resistance improver is limited. Was inadequate. When a well-known weather resistance improver is mixed into the base film or the adhesive in an excessive amount to impart sufficient weather resistance, the physical strength of the base film may be reduced, or the weather resistance improver may adhere to the base film. Bleeding out at the interface of the agent with the passage of time reduces the adhesion between the base film and the pressure-sensitive adhesive, and causes problems such as extremely easy generation of adhesive residue and fogging of the coating film surface when peeled from the adherend. Yes, satisfactory weather resistance has not yet been obtained. In addition, recently, temporary storage outdoors and long hauling of transportation have been progressing,
At present, there is a need for a pressure-sensitive adhesive sheet for protecting automotive coatings having better weather resistance.

[0007]

SUMMARY OF THE INVENTION The present invention provides a pressure-sensitive adhesive sheet for protecting automotive coatings, which has excellent weather resistance, has little deterioration of the base film and pressure-sensitive adhesive, and does not cause breakage of the base film or adhesive residue. The purpose is to do.

[0008]

Generally, an automotive coating protective film is processed into a tape shape, so that a release agent is applied to the surface opposite to the pressure-sensitive adhesive layer, and the structure of the release agent layer / substrate film / pressure-sensitive adhesive layer is constituted. become. Therefore, the present inventors, when pasting the coating film protective film to the coating film of the car, the first to receive the sunlight is the release agent layer, adding a weather resistance improver to this layer, sunlight, especially It has been found that by preventing the transmission of ultraviolet rays, it is possible to extremely efficiently prevent the deterioration of the base film as well as the deterioration of the adhesive. In addition, by adding a weather resistance improver to the release agent layer, the amount of the weather resistance improver conventionally compounded in the base film or the adhesive can be reduced, so that the weather resistance from the base film or the adhesive is improved. Bleed-out of the coating agent can be reduced, and it has been found that contamination of the coating film due to deterioration of adhesion between the film substrate and the adhesive and penetration of the weather resistance improving agent from the adhesive can be minimized. .

That is, the present invention provides a pressure-sensitive adhesive sheet for protecting automotive coatings, comprising a polyolefin resin as a base film, an adhesive layer provided on one side of the base film, and a release agent layer formed on the other side. The release agent layer is the release agent 1
0.1 to 2 parts by weight of a weather resistance improver is blended with respect to 00 parts by weight, the pressure-sensitive adhesive layer uses a rubber-based pressure-sensitive adhesive, and the pressure-sensitive adhesive sheet has a light transmittance of 1% at a wavelength of 295 nm to 400 nm. A pressure-sensitive adhesive sheet for protecting automotive coatings, characterized in that:

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The polyolefin resin used as the base film of the present invention is ethylene, propylene, α- such as butene.
Olefin homopolymers and copolymers, as well as monomer copolymers such as vinyl acetate and methyl methacrylate,
Alternatively, a mixture thereof may be used. In addition, ultraviolet absorbers, light stabilizers, antioxidants, plasticizers, antistatic agents, etc. may be added for the purpose of improving the weather resistance, heat resistance, processability and workability of the base film. It should be kept within a range that does not cause a trouble such as a decrease in physical strength of the film.

Further, the base film is preferably colored white. The reason for this is that, by coloring in white, sunlight is reflected, and a rise in the temperature of the coating film is suppressed as much as possible. Examples of the coloring agent include titanium oxide, zinc oxide, lithopone, lead white, barium sulfate, alumina white, silica white, clay, and the like. In particular, it is preferable to use titanium oxide which has excellent shielding properties and high whiteness, and when this is contained in the base film, the effect is great. The mixing amount of the colorant is 7 per 100 parts by weight of the polyolefin resin.
-30 parts by weight, preferably 9-20 parts by weight. When the amount is less than 7 parts by weight, the coloring is small and the shielding property is insufficient, and when it exceeds 30 parts by weight, the film strength becomes weak. The thickness of the base film may be appropriately determined depending on the composition and use, but is usually about 20 to 150 μm. If the thickness is less than 20 μm, the resistance to trauma may be poor.
It is not preferable because of poor economic efficiency.

As the release agent used in the present invention, water, solvent-type or non-solvent-type silicones, fluororesins, long-chain alkyl compounds and the like can be used. An essential requirement is to form a release agent layer by mixing a weather resistance improver with these release agents and applying them to a base film. Known UV absorbers, antioxidants, light stabilizers, etc. can be added as weather resistance improvers, but in particular, UV rays harmful to the base film are absorbed by the release agent layer before reaching the base film. Since it is important that the ultraviolet absorber be used, an ultraviolet absorber is preferred.

The ultraviolet absorber may be appropriately determined from known benzotriazole-based, benzophenone-based, benzoate-based ultraviolet absorbers and the like according to the use conditions.
-(2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chloro-benzotriazole, 2- (2 ' -Hydroxy-3 ', 5'-di-t-amylphenyl) -benzotriazole, 2-
(2'-hydroxy-5'-t-octylphenyl)-
Benzotriazole ultraviolet absorbers such as benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-noctoxybenzophenone,
Benzophenone-based ultraviolet absorbers such as 2-historoxy-4-benzyloxybenzophenone; 2,4-di-t-
Butylphenyl-3 ', 5'-di-t-butyl-4'-
Examples include benzoate-based ultraviolet absorbers such as hydroxybenzoate.

As antioxidants, 2,6-di-t-butyl-p-cresol, 2,2'-methylenebis- (4
-Methyl-6-t-butylphenol), tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4 ′)
-Hydroxyphenyl) propione], sulfur-based antioxidants such as dilaurylthiodipropionate, simiristylthiodipropionate, and phosphorus such as triphenylphosphite and diphenylindesylphosphite. Acid-based antioxidants;

Examples of the light stabilizer include dimethyl succinate / 1- (2-hydroxymethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate,
Hindered amine light stabilizers such as bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and the like can be mentioned.

The release agent containing the weather resistance improver is applied to the substrate at a dry weight of about 0.05 to 3 g / m ² and then forms a release agent layer by heat curing, ionizing radiation curing, or the like. I do. In order to prevent the performance of the release agent layer from being remarkably deteriorated, the amount of the weather resistance improver is specifically 0 to 100 parts by weight of the release agent. It should be limited to 1 to 2 parts by weight, preferably 0.5 to 1 part by weight. If the amount is less than 0.1 part by weight, the base film may be deteriorated when exposed to sunlight for a long time. Also, 2
If the amount exceeds the weight part, the weather resistance improver may bleed out to the release agent layer. The base film may be provided with a known corona treatment or an anchor coat layer before providing the release agent layer. The anchor coat layer may contain the weather resistance improver.

The pressure-sensitive adhesive used in the pressure-sensitive adhesive sheet for protecting automotive coatings of the present invention includes a rubber-based pressure-sensitive adhesive. For example, a rubber-based polymer such as natural rubber, polyisobutylene, isobutylene-isoprene copolymer, isobutylene-1-butene copolymer, isobutylene-n-butene copolymer is used as a main component, and if necessary, a tackifier,
A softener, a filler, a release agent, and a pigment can be appropriately blended. It is also possible to add a weather resistance improver, but it is liable to cause contamination of the paint film for automobiles. The application amount of the adhesive is 5 to 30 g / m ² , more preferably 7 to ²⁰ g in dry weight.
/ M ² . By the way, 5g / m ²
If less than 30 g / m ² , the adhesive performance becomes insufficient.
If it exceeds, the adhesive may protrude and cause cohesive failure. It is to be noted that pressure-sensitive adhesives other than rubber-based pressure-sensitive adhesives, such as acrylic-based and vinyl ether-based pressure-sensitive adhesives, are difficult to withstand severe temperature conditions, and are not preferably used.

The base film of the present invention is prepared by blending the above-mentioned additives and colorant with the polyolefin resin and then forming the film by a conventionally known method, for example, a commonly used extruder such as a T-die and an inflation device. Manufactured. Further, if necessary, a corona treatment or an anchor coat layer may be provided.

A release agent containing a weather resistance improving agent is applied to the surface on which the pressure-sensitive adhesive layer is not formed. Examples of the application device include a reverse coater, a knife coater, a bar coater, a die coater, a gear-in die coater, and a slot die coater. , An air knife coater, a reverse gravure coater, a bario gravure coater and the like are used as appropriate.

On the other hand, to form a pressure-sensitive adhesive layer on one side of the base film, a coating solution in which the pressure-sensitive adhesive is dissolved in a soluble solvent such as toluene may be applied and dried. A reverse coater, knife coater, bar coater, die coater, gear-in die coater, slot die coater, air knife coater, reverse gravure coater, bario gravure coater and the like are used as appropriate.

[0021]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted to such specific Examples. In the examples, the coating amount, the number of copies, the mixing ratio, and the like are all represented by solid content weight.

[0022]

[Example 1] [Production of base film] A resin composition obtained by blending 10 parts by weight of rutile type titanium oxide with 100 parts by weight of a mixture of polypropylene / polyethylene (80 parts by weight / 20 parts by weight) was subjected to a T-die method. Was formed into a film having a thickness of 50 μm to obtain a substrate film.

[Formation of Release Agent Layer] Both sides of this substrate film were subjected to corona discharge treatment, and one side was coated with a long-chain alkyl-based release agent 1
A benzotriazole-based ultraviolet absorber (trade name: SEESORB 709, made by Shiraishi calcium) for 00 parts by weight (trade name: Piroyl 1010, on the other hand, manufactured by YAS Corporation)
0.1 parts by weight of a releasing agent toluene solution is applied by a gravure coater so that the dry weight becomes 1 g / m ² ,
After drying, a release agent layer was formed.

[Production of pressure-sensitive adhesive sheet] Then, a pressure-sensitive adhesive containing polyisobutylene as a main component (trade name: Vistanex MML-80,
Exxon Co., Ltd.) was applied with a knife coater to a dry weight of 15 g / m ² , dried and wound up in a tape form to obtain an adhesive sheet for protecting automotive coatings of the present invention.

[0025]

Example 2 A pressure-sensitive adhesive sheet for protecting automotive coatings was prepared in the same manner as in Example 1, except that the amount of the ultraviolet absorber incorporated in the release agent layer was changed to 2 parts by weight.

[0026]

Example 3 A benzophenone-based ultraviolet absorber (trade name: SEESORB10) was used as an ultraviolet absorber to be mixed in the release agent layer.
(2, made of Shiroishi calcium), except that an adhesive sheet for protecting automotive coatings was prepared in the same manner as in Example 1.

[0027]

EXAMPLE 4 A benzoate-based ultraviolet absorber (trade name: SEESORB 71) was used as an ultraviolet absorber to be mixed in the release agent layer.
(2, made of Shiroishi calcium), except that an adhesive sheet for protecting automotive coatings was prepared in the same manner as in Example 1.

[0028]

Comparative Example 1 A pressure-sensitive adhesive sheet for protecting automotive coatings was prepared in the same manner as in Example 1 except that no ultraviolet absorber was added to the release agent layer.

[0029]

Comparative Example 2 A pressure-sensitive adhesive sheet for protecting automotive coatings was prepared in the same manner as in Example 1 except that the amount of the ultraviolet absorber incorporated in the release agent layer was changed to 0.05 parts by weight.

[0030]

Comparative Example 3 A pressure-sensitive adhesive sheet for protecting automotive coatings was prepared in the same manner as in Example 1 except that the amount of the ultraviolet absorber incorporated in the release agent layer was changed to 2.5 parts by weight.

The pressure-sensitive adhesive sheet for protecting automobile coating films thus obtained was evaluated as described below, and the obtained results are shown in Table 1.

[Evaluation] Accelerated weathering test A test piece was placed in a Sunshine Ink Senon Long Life Weather Meter (manufactured by Suga Test Instruments) and subjected to one cycle (temperature 63).
140 ° C., 40% RH × 6 hours → rain × 20 minutes → temperature 23 ° C., 65% RH × 1 hour) 140 times.

Evaluation of Initial Adhesive Strength The obtained adhesive sheet for protecting automobile coating films was adhered to a steel plate having a black alkyd / melamine coating film according to JIS Z0.
Evaluation was performed by 180 ° peeling according to 237.

Evaluation of Adhesive Strength and Removability after Weathering Test A pressure-sensitive adhesive sheet for protecting automobile coating films was adhered to a steel plate having a black alkyd / melamine coating film, subjected to an accelerated weathering test, and then subjected to 180 according to JIS Z0237. The adhesive strength at ℃ and the removability after peeling (adhesive residue, film deterioration) were evaluated. The evaluation criteria for removability are as follows. Re-peelability (adhesive residue) ○: no adhesive residue △: slight adhesive residue ×: large adhesive residue Re-peelability (film deterioration) ○: no film damage △: slight film damage (on steel plate) ×: Film breakage is large (30% or more of film remains on steel plate)

Measurement of transmittance The transmittance of the pressure-sensitive adhesive sheet for protecting automobile coating films (measurement wavelength range 2
95 to 400 nm) was measured with a self-recording spectrophotometer U-3500 (manufactured by Hitachi).

Comprehensive Evaluation The above test results were comprehensively evaluated. Comprehensive evaluation criteria ○ ・ ・ ・ ・ Excellent △ ・ ・ ・ ・ Some problems x ・ ・ ・ ・ Cannot be used to protect automotive coatings

[0037]

[Table 1]

[0038]

As is clear from the examples, the pressure-sensitive adhesive sheet for protecting automobile coating films of the present invention has particularly excellent weather resistance, has little deterioration of the base film and the pressure-sensitive adhesive, and has a high possibility of breaking the base film. It is an adhesive sheet for automobile coating film protection without adhesive residue.

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[Procedure amendment]

[Submission date] September 24, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art Conventionally, a painted new vehicle or its parts are loaded on a truck or ship and transported to a remote place such as overseas, or temporarily indoors or outdoors until the new vehicle reaches the user's hand. When stored (2 to 12 months), various suspended or colliding substances such as acid rain, dust, and dust may cause damage to the paint film, fogging, gloss blur, and discoloration. Have been. As such means, spray coating such as paraffin wax has a thickness of 5 to 5.
A method of providing a protective film of 20 μm has been known. However, the coating film of wax easier Maternal Oyo effect on protection performance occurs variations in thickness, further to or paint coating wax is lowered protection performance to oxidative deterioration by sunlight for the main component There is a problem that the wax permeates and discolors. In addition, the work of painting and removing the wax requires a great deal of work, and the use of a solvent as a remover requires a wastewater treatment facility, so that there are many problems from the working environment.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

[0022]

[Example 1] [Production of base film] A resin composition obtained by blending 10 parts by weight of rutile type titanium oxide with 100 parts by weight of a mixture of polypropylene / polyethylene (80 parts by weight / 20 parts by weight) was subjected to a T-die method. Was formed into a film having a thickness of 50 μm to obtain a substrate film.

Claims (2)

[Claims] 1. A pressure-sensitive adhesive sheet for protecting automotive coatings comprising a polyolefin resin as a base film, an adhesive layer provided on one side of the base film and a release agent layer formed on the other side. The adhesive layer contains 0.1 to 2 parts by weight of a weather resistance improver per 100 parts by weight of the release agent, the adhesive layer uses a rubber-based adhesive, and the wavelength of the adhesive sheet is 2
An adhesive sheet for protecting automotive coatings, wherein the light transmittance at 95 nm to 400 nm is 1% or less. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the weatherability improving agent is at least one selected from an ultraviolet absorber, an antioxidant, and a light stabilizer.