JPH11291411A - Surface protection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contamination of an etching solution and an alkaline solution and hydrolysis of a substrate surface in an etching step and a resist removing step in manufacturing a shadow mask, and to be capable of peeling from an adherend when peeling off. Is provided. SOLUTION: This is a surface protective film in which a pressure-sensitive adhesive layer is formed on a base film containing at least 70% of a polypropylene resin, wherein the pressure-sensitive adhesive layer comprises a (meth) acrylate monomer and a functional group. A copolymer with a vinyl-based monomer having a cross-linking agent capable of reacting with the functional group is crosslinked, and the glass transition temperature of the copolymer determined by the Fox equation is −25 to −10 ° C., and the A surface protective film, wherein the solvent-insoluble content of the pressure-sensitive adhesive layer is 85% by weight or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used to temporarily adhere to the surface of various plate-like members having relatively flat surface irregularities, and to protect the surface so that dust does not adhere or be damaged. Regarding the surface protection film, more specifically,
The present invention relates to a surface protective film suitably used for protecting a resist film or an etching resistive film provided on a non-etched surface in an etching step in manufacturing a shadow mask.

[0002]

2. Description of the Related Art In an etching process at the time of manufacturing a shadow mask, a resist film or an etching resistance film is provided on a surface opposite to a surface to be etched. Usually, a surface protective film is stuck thereon so that these films are protected from the etching solution. Then, after achieving the purpose of surface protection, the film is peeled off. Conventionally, as this surface protective film, a film in which a layer made of an acrylic pressure-sensitive adhesive is provided on one side of a polyester film and a layer made of a silicone-based release agent is provided on the other side thereof has been used.

[0003]

However, when the above-mentioned surface protective film is used, the silicone-based release agent falls off in the etching step using an acidic etching solution and the resist removing step using an alkaline solution, and the acidic etching solution and the alkaline solution are removed. There was a problem of contamination. Further, since the surface of the polyester film is easily hydrolyzed by an acidic etching solution or an alkaline solution and heat during the process, the wettability of water on the back of the polyester film is improved, and the water washing after removing the resist is performed.
There is a problem that water remains on the back of the polyester film even after the drying step. Further, the acrylic pressure-sensitive adhesive used in the above-mentioned surface protection film is easily affected by heat in each step, and thus the adhesive strength tends to increase. Therefore, when the purpose of surface protection is achieved, when the surface protection film is peeled off. In addition, there has been a problem that the removability from the adherend is poor, and the shadow mask material is sometimes deformed.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to prevent contamination of an etching solution and an alkaline solution and hydrolysis of a substrate surface in an etching step and a resist removing step in manufacturing a shadow mask. Another object of the present invention is to provide a surface protective film having good releasability from an adherend when peeled off.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies, studies, and studies to achieve the above-mentioned problems, and have finally completed the present invention. That is, the present invention is as follows. A surface protection film in which an adhesive layer is formed on a substrate film containing 70% or more of a polypropylene resin, wherein the adhesive layer is a vinyl having a (meth) acrylate monomer and a functional group. A copolymer with a system monomer is cross-linked with a cross-linking agent capable of reacting with the functional group, the glass transition temperature of the copolymer determined by the Fox equation is −25 to −10 ° C., and the pressure-sensitive adhesive is A surface protective film, wherein the solvent-insoluble content of the layer is 85% by weight or more.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in more detail.
The surface protective film of the present invention comprises polypropylene resin
An adhesive layer is formed on a base film containing 0% or more. This pressure-sensitive adhesive layer is obtained by crosslinking a copolymer of a (meth) acrylate monomer and a vinyl monomer having a functional group with a crosslinking agent capable of reacting with the functional group.

[0007] The (meth) acrylate monomer used in the present invention includes, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate. , Octyl acrylate, octyl methacrylate,
Examples include alkyl (meth) acrylates such as nonyl acrylate, nonyl methacrylate, dodecyl acrylate, and dodecyl methacrylate. These alkyl portions may be linear or branched. Also, these (meth) acrylate monomers are
One kind may be used alone, or two or more kinds may be used in combination.

The vinyl monomer having a functional group used in the present invention includes, for example, vinyl monomers having a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid and maleic acid; 2-hydroxyethyl ( Vinyl monomers having a hydroxyl group such as (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxyhexyl (meth) acrylate are exemplified. One of these vinyl monomers may be used alone, or two or more thereof may be used in combination.

The content of the vinyl monomer having a functional group is preferably 0.5 to 10 mol% based on all the monomers constituting the copolymer. When the content is less than 0.5 mol%, the copolymer cannot be sufficiently crosslinked by a crosslinking agent described later, and the solvent-insoluble content of the pressure-sensitive adhesive layer decreases. The content is more preferably 1 to 8 mol%.

A copolymer of the above (meth) acrylate monomer and the above-mentioned vinyl monomer having a functional group can be produced by a conventionally known method. Further, a polymerization initiator or the like can be used as needed.

In the copolymer, Fo shown below is used.
The glass transition temperature determined by the equation of x is −25−−.
The temperature is 10C, preferably -23 to -12C.

[0012]

(Equation 1)

Here, Tgmix represents the Tg of the copolymer, Tg1, Tg2, Tg3,... Represent the Tg of the first monomer, the second monomer, the third monomer,. W1, W2, W3,...
, The second monomer, the third monomer,...
Shows the weight fraction of

When the glass transition temperature is less than -25 ° C., when a surface protective film having an adhesive layer obtained from such a copolymer is attached to a resist film or the like,
The viscosity of the pressure-sensitive adhesive layer is greatly reduced by heat during the steps such as the etching step, and the etchant permeates the interface between the pressure-sensitive adhesive layer and the resist film from the end of the pressure-sensitive adhesive layer, and plays a role in protecting the resist film. Disappears. Conversely, when the glass transition temperature exceeds −10 ° C., the initial pressure-sensitive adhesive strength at room temperature of the pressure-sensitive adhesive layer obtained from such a copolymer is insufficient,
When the surface protective film is attached to the resist film, the film peels off, or the etchant seeps into the interface between the adhesive layer and the resist film from the edge of the adhesive layer, and plays a role in protecting the resist film. Disappears.

The pressure-sensitive adhesive layer is formed by crosslinking the copolymer with a crosslinking agent. The crosslinking is caused by the reaction between the functional group of the vinyl monomer and the crosslinking agent. The cross-linking agent is a compound having at least two groups capable of reacting with the functional group of the above-mentioned vinyl monomer, for example, a polyfunctional isocyanate compound such as trimethylolpropane tolylene diisocyanate and methylene diisoyanate. Polyglycidylamine compounds such as tetraglycidyl metaxylenediamine, tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyldiaminodiphenylmethane, triglycidyl p-aminophenol, diglycidylaniline, and diglycidyl o-toluidine. One of these crosslinking agents may be used alone, or two or more thereof may be used in combination.

In the present invention, the solvent-insoluble content of the pressure-sensitive adhesive layer is at least 85% by weight, preferably at least 90% by weight. If the solvent-insoluble content is less than 85% by weight, the peelability from the adherend when peeling off the surface protective film after achieving the purpose of surface protection becomes poor, and there is a practical problem.

In the present invention, the solvent insoluble content is measured by the following method. That is, about 0.1 g of the pressure-sensitive adhesive layer of the surface protective film is sampled, precisely weighed (a (g)), wrapped in a Teflon film, and immersed in ethyl acetate. One week after immersion, the weight after drying is measured (b (g)), and the solvent insoluble content is determined by the following equation. Solvent insoluble content (% by weight) = (b / a) × 100

The amount of the crosslinking agent depends on the content of the vinyl monomer having a functional group used in the copolymer, but is preferably 1 to 10 parts by weight based on 100 parts by weight of the copolymer. Parts by weight, more preferably 2 to 8 parts by weight.
If the amount is less than 1 part by weight, the copolymer is not sufficiently crosslinked, and the solvent-insoluble content of the pressure-sensitive adhesive layer tends to be low. Conversely, if the amount exceeds 10 parts by weight, the initial adhesive strength of the pressure-sensitive adhesive layer tends to be insufficient.

The surface protective film of the present invention contains 70% by weight or more, preferably 75% by weight of polypropylene as a base material.
Use a film containing more than weight%. If the content of polypropylene is less than 70% by weight, the base film changes its dimensions due to heat in the etching step, the surface protection film floats from the adherend (resist film), and the etching solution is removed from the adhesive layer. It permeates between the resist films. In the present invention, the polypropylene includes a generally known polypropylene resin such as a homopolymer, a random copolymer, and a block copolymer.

The base film contains 30% by weight.
In the following range, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene,
A polyolefin-based resin such as an ethylene-α-olefin copolymer or an ethylene-n-butyl acrylate copolymer may be mixed.

As the method for forming the pressure-sensitive adhesive layer on the substrate film, a conventionally known method is employed. However, after applying a solution of the pressure-sensitive adhesive composition containing the copolymer and the cross-linking agent, the solution is heated and the like. A method of crosslinking the composition is preferred.

In the surface protective film of the present invention, since the solvent-insoluble content of the pressure-sensitive adhesive layer is 85% by weight or more, the adhesive force of the pressure-sensitive adhesive layer hardly changes with time and is almost the same as the initial adhesive force. After achieving the purpose of surface protection, when the surface protection film is peeled off, the releasability from the adherend becomes good.

Further, in the surface protective film of the present invention, since the glass transition temperature of the copolymer in the pressure-sensitive adhesive layer is in a specific range, when the surface protective film is attached to a resist film, the film peels off. The etching solution does not soak into the interface between the pressure-sensitive adhesive layer and the resist film from the edge of the pressure-sensitive adhesive layer.

In the surface protective film of the present invention, since the base film is a polypropylene film, unlike the polyester film, it is not hydrolyzed by an acidic etching solution in the etching step or an alkali in the resist removing step. In addition, the wettability of the base film against water is not improved. Therefore, water does not remain on the substrate film surface after the subsequent drying step.

Further, in the surface protective film of the present invention, the content of polypropylene in the base film is 70%.
% Or more, the base film hardly changes its dimensions due to heat in the etching process, so that the surface protection film floats from the adherend (resist film), and the etching solution flows between the adhesive layer and the resist film. It does not soak.

Further, in the surface protective film of the present invention, since the silicone-based release agent layer is not formed on the surface of the base film opposite to the surface on which the pressure-sensitive adhesive layer is formed, the etching solution or the alkali in the etching step or the resist removing step is not used. Does not contaminate the liquid.

[0027]

The present invention will be specifically described below with reference to examples. The methods for measuring the properties are shown below. 1) Glass transition temperature (Tg) of copolymer It was determined from the following equation assuming that it follows the equation of Fox.

[0028]

(Equation 2)

Here, Tgmix indicates the Tg of the copolymer, Tg1, Tg2, Tg3,... Indicate the Tg of the first monomer, the second monomer, the third monomer,. W1, W2, W3,...
, The second monomer, the third monomer,...
Shows the weight fraction of

2) Solvent-insoluble content (% by weight) of the pressure-sensitive adhesive layer About 0.1 g of the pressure-sensitive adhesive layer was sampled from the surface protective film, precisely weighed (a (g)), wrapped in a Teflon film, and acetic acid was added. Soak in ethyl. One week after immersion, the weight after drying was measured (b
(G)), and the solvent insoluble content was determined by the following equation. Solvent insoluble content (% by weight) = (b / a) × 100

3) A photosensitive agent solution having the following composition was applied to an iron-nickel alloy thin plate for a shadow mask having an initial adhesive strength of 0.14 mm, and dried at 80 ° C. for 3 minutes to form a photosensitive film having a thickness of about 5 μm. . Acid casein solution (TS-50 stock solution manufactured by Fuji Pharmaceutical Co., Ltd.) 40 kg Polyvinyl alcohol (GL-05 stock weight manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 0.69 kg Ammonium dichromate (stock weight) 0.4 kg or more water To add a viscosity of 70 cp at 20 ° C.
And Using this photosensitive film as the surface to be adhered, a surface protective film was bonded using a laminator at a pressure of 8 kg / cm (linear pressure conversion) at a speed of 0.3 m / min. Thereafter, the peeling force when the surface protective film was peeled at a tensile speed of 0.3 m / min and an angle of 180 ° was defined as the initial adhesive force. In the present invention, it is preferable that the initial adhesive strength is about 10 to 150 gf / 20 mm.

4) Penetration test of etchant A surface protective film was bonded to the photosensitive film used in the measurement of the initial adhesive strength at a pressure of 8 kg / cm (linear pressure conversion) at a speed of 0.3 m / min using a laminator. This was immersed in a ferric chloride solution (Bohm concentration 45 °, solution temperature 60 ° C.) for 10 minutes. Then, after taking out and washing with water, it was visually evaluated whether or not the liquid had permeated the interface between the photosensitive film and the pressure-sensitive adhesive layer.

5) Peeling Force A surface protective film was attached to the photosensitive film used in the measurement of the initial adhesive force by using a laminator at a pressure of 8 kg / cm (linear pressure conversion) at a speed of 0.3 m / min. For 10 minutes, then at 90 ° C. for 10 minutes, and further at 120 ° C. for 1 minute. Thereafter, the peeling force when the surface protective film was peeled off at a tensile speed of 0.3 m / min and an angle of 180 ° was measured. In the present invention, the peel force is 10 to 200 gf / 2.
It is good if it is about 0 mm.

EXAMPLE 1 68 parts by weight of butyl acrylate, 29 parts by weight of methyl methacrylate, 3 parts by weight of 2-hydroxyethyl acrylate, and a polymerization initiator were placed in a reaction vessel equipped with a cooling pipe, a nitrogen introducing pipe, a thermometer, and a stirrer. 2,2′-azobis (2-
0.1 part by weight of amidinopropane) dichloride, 1.5 parts by weight of sodium dodecylbenzenesulfonate and 100 parts by weight of water as emulsifiers were added, emulsion polymerization was carried out at 80 ° C. for 5 hours, and the pH was adjusted to 7 with 15% by weight aqueous ammonia. It was adjusted to 0 to obtain a copolymer emulsion having a solid content of 50% by weight.
This emulsion was salted out with hydrochloric acid, and then washed with water and dried to obtain an acrylic copolymer. This acrylic copolymer was dissolved in toluene, and 3 parts by weight of trimethylolpropane tolylene diisocyanate was added to this solution and mixed with 100 parts by weight of the solid content of the acrylic copolymer to obtain an adhesive composition solution. On a 30 μm-thick homopolypropylene film with a corona treatment on one side, the coating after drying is 5 μm
This solution was applied so that the pressure-sensitive adhesive layer was dried in a dryer at 80 ° C. for 2 minutes to form an adhesive layer, thereby obtaining a surface protective film.

Example 2 A surface protective film was obtained in the same manner as in Example 1, except that 64 parts by weight of butyl acrylate and 33 parts by weight of methyl methacrylate were used.

Example 3 A surface protective film was obtained in the same manner as in Example 1, except that butyl acrylate was used in an amount of 60 parts by weight and methyl methacrylate was used in an amount of 37 parts by weight.

Example 4 The same adhesive composition solution as in Example 2 was applied onto a 40 μm thick film (homopolypropylene / low-density polyethylene = 70/30 (weight ratio) blend film) having one surface subjected to corona treatment. Coating and drying were performed in the same manner as in Example 1 to obtain a surface protective film.

Comparative Example 1 A surface protective film was obtained in the same manner as in Example 1, except that 79 parts by weight of butyl acrylate and 18 parts by weight of methyl methacrylate were used.

Comparative Example 2 A surface protective film was obtained in the same manner as in Example 1 except that butyl acrylate was used in an amount of 59 parts by weight and methyl methacrylate was used in an amount of 38 parts by weight.

Comparative Example 3 The same adhesive composition solution as in Example 2 was applied to a 40 μm-thick film (homopolypropylene / low-density polyethylene = 60/40 (weight ratio) blend film) having one surface subjected to corona treatment. Coating and drying were performed in the same manner as in Example 1 to obtain a surface protective film.

Comparative Example 4 A surface protective film was obtained in the same manner as in Example 2 except that trimethylolpropane tolylene diisocyanate was changed to 1 part by weight based on 100 parts by weight of the polymer solid content. .

The copolymers of Examples 1 to 4 and Comparative Examples 1 to 4, the solvent-insoluble content of the pressure-sensitive adhesive layer, and the surface protective film were evaluated. Table 1 shows the results.

[0043]

[Table 1]

[0044]

As is apparent from the above description, since the surface protective film of the present invention has a high solvent-insoluble content of the pressure-sensitive adhesive layer, the surface protective film can be removed after achieving the purpose of surface protection. It has good releasability from the adherend.
Further, the surface protective film of the present invention, since the glass transition temperature of the copolymer in the pressure-sensitive adhesive layer is in a specific range, when the surface protective film is attached to a resist film, without peeling the film, Further, the etchant does not soak into the interface between the pressure-sensitive adhesive layer and the resist film from the end of the pressure-sensitive adhesive layer. Further, since the base film is a polyolefin film, the base film is not hydrolyzed by the acidic etching solution in the etching step or the alkali in the resist removing step, so that the wettability of the base film with water does not improve, and No water remains on the substrate film surface after the drying step. Furthermore, since the content of polypropylene in the base film is 70% by weight or more,
Since the base film hardly changes its dimensions due to heat in the etching process, the surface protective film does not float from the adherend (resist film), and the etching solution does not seep between the adhesive layer and the resist film. . Therefore, the surface protection film of the present invention is suitably used particularly for protecting a resist film or an etching resistance film provided on an unetched surface in an etching step in manufacturing a shadow mask.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C09J 163/00 C09J 163/00 175/04 175/04 // C08G 18/62 C08G 18/62

Claims (1)

[Claims] 1. A surface protective film comprising an adhesive layer formed on a base film containing at least 70% of a polypropylene resin, wherein the adhesive layer comprises a (meth) acrylate monomer and a functional group. Is crosslinked with a crosslinking agent capable of reacting with the functional group, and the glass transition temperature of the copolymer obtained by the Fox equation is −
25 to -10 ° C, and the solvent-insoluble content of the pressure-sensitive adhesive layer is 8
A surface protective film having a content of 5% by weight or more.