JPH09267449A - Surface protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface protective film generating no peeling change when a separator is peeled and excellent in long-term antistatic properties resulting in excellent workability by successively laminating an antistatic layer and a self-adhesive layer on the single surface of a transparent support. SOLUTION: If necessary, a separator composed of paper or a plastic film can be provided on the self-adhesive layer and a release layer can be also provided on the other surface of the transparent support. As the transparent support, a support high in light transmissivity is pref. and there is a transparent plastic film composed of polyester or polycarbonate. The antistatic layer is pref. constituted of a polymer containing a monomer having an ion conductive group in its side chain from an aspect of antistatic effect and an acrylic self-adhesive or a rubbery self-adhesive is used in the self-adhesive layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface protective film used for originals for printed boards, printed matter, etc., and more particularly to a surface protective film suitably used for exposing a photoresist having tackiness in plate making and the like.

[0002]

2. Description of the Related Art Normally, printed wiring boards and resin letterpress plates are
It is prepared by contact-exposing an exposure original document to an adhesive photoresist such as a liquid photoresist. Since such an exposure document is used in close contact with the photoresist, if the surface of the document is not subjected to any treatment, a part of the photoresist is transferred to the document surface when the document is peeled off after the exposure is finished and stains are removed. Will occur. Under these circumstances, a surface protective film has been conventionally provided on the surface of the exposure original facing the photoresist to prevent the photoresist from adhering to the original.

However, when the photoresist adheres to the surface of the surface protective film, there is a problem in that the cleaning and replacement of the surface protective film are forced and the exposure operation becomes complicated. It is proposed to form a pressure-sensitive adhesive layer and to form a release layer on the other surface to prevent the adhesion of photoresist and to add antistatic property, such as surfactant and metal fine powder. (Actual Kaihei 3-114845).

However, although such a protective film has a sufficient antistatic effect in a general use method, it has the following drawbacks particularly when used for a long period of time. That is, a protective film to which an antistatic effect is added by adding a surfactant or a fine metal powder tends to decrease the strength of the release layer, yellows due to the influence of exposure ultraviolet light for a long period of time, and transmits light. A decrease in the rate is recognized.
Further, when a surfactant is used, stickiness occurs on the surface of the release layer, and when the surface protective film is wound into a roll, the surfactant moves to the adhesive layer and the release layer is charged. There is also a problem that the prevention effect decreases with time.

On the other hand, the adhesive layer of the surface protective film is usually
It is covered with a release sheet called a separator, and when used, the release sheet is peeled off and the adhesive layer is pasted to the surface of the object, but the conventional adhesive layer has no antistatic effect. When the release sheet was peeled off, static electricity was generated, and as a result, dust, dust, and the like adhered to the adhesive layer, leading to a decrease in yield during bonding. However, a method of adding a surfactant to the adhesive layer in order to solve such a problem is also conceivable, but if added to the extent that the antistatic effect is exhibited, the physical properties of the adhesive layer itself will change and I can't stand it.

[0006]

SUMMARY OF THE INVENTION The present invention has been made under such a background, and an object thereof is to prevent peeling electrification when the separator is peeled off and to have excellent antistatic property for a long period of time. As a result, it is to provide a surface protective film having excellent workability.

[0007]

In order to solve the above problems, the present invention provides a surface protective film comprising a transparent support and an antistatic layer and a pressure-sensitive adhesive layer provided on one surface of the transparent support in this order. Further, it is preferable that the antistatic layer contains a polymer having ionic conductivity.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The surface protective film of the present invention comprises an antistatic layer and a pressure-sensitive adhesive layer provided in this order on one surface of a transparent support as described above. It may have a separator made of a film or the like. Further, a release layer may be provided on the other surface of the transparent support.

The transparent support preferably has a high light transmittance, and examples thereof include transparent plastic films such as polyester, polycarbonate, polypropylene, triacetyl cellulose, polyvinyl chloride, acryl and polystyrene. The transparent support may be subjected to a surface treatment for improving the adhesion to the antistatic layer described later. Further, the thickness affects the resolution in the case of use as an exposure original document, and therefore 1 to 25 μm, preferably 3 to
A thin film of about 12 μm is preferable. When the surface protective film of the present invention is used for contact exposure, a matte layer may be formed on the surface thereof to improve vacuum adhesion, and a pigment is kneaded into the substrate itself. You may use the thing. The pigment may be inorganic or organic and its type,
Highly transparent resin beads of acrylic, silicone, polyethylene, polypropylene or the like are preferable so as not to hinder the transparency as much as possible.

The antistatic layer formed on one surface of the transparent support is preferably composed of a polymer imparted with ionic conductivity so as to most effectively exert the effects described below.

The polymer having ionic conductivity is a polymer containing a monomer having an ionic conductive group in its side chain. The monomer having an ion conductive group in such a side chain may be any of a cation type, a zwitterion type, an anion type and a nonion type, but a cation type,
Since the amphoteric ion type has greater ionic conductivity than the anionic type and nonionic type and is effective in suppressing charging, it is desirable to use a cation type or zwitterionic type monomer. The monomer having such a cation-type ion conductive group is a polymerizable monofunctional vinyl monomer having a quaternary ammonium group at the terminal, and specifically, dimethylaminoethyl acrylate quaternary chloride and dimethylamino. Ethyl methacrylate quaternary chloride, diethylaminoethyl acrylate 4
Examples thereof include quaternary chloride, diethylaminoethyl methacrylate quaternary chloride, p-dimethylaminostyrene quaternary chloride and p-diethylaminostyrene quaternary chloride. On the other hand, examples of the monomer having a zwitterionic ion-conductive group include betaine compounds of the above monomers, and these monomers can be used alone or in combination of two or more.

The monomer having an ion conductive group on the side chain is a monofunctional vinyl monomer having a hydroxy group at the terminal such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, or the monofunctional vinyl monomer. Acrylic acid, methacrylic acid and its esters, styrene and its derivatives, other monofunctional vinyl monomers such as vinyl acetate (other monomers, the same applies hereinafter) that are copolymerizable with the monomers, especially It is preferably used by copolymerizing with a monomer having a hydroxy group and a monomer having a carboxyl group.

The antistatic layer of the present invention is mainly composed of the above-mentioned copolymer having ionic conductivity, but a crosslinking agent, a curing agent or the like can be added if necessary.
If the antistatic layer is cured by adding such a crosslinking agent or a curing agent, the workability of the pressure-sensitive adhesive application work described below is improved.
Glycidyl derivatives such as epoxy resins and amines and polyamide resins as their curing agents, and polyester resin / isocyanate derivatives and the like can be used as effective additives.

The monomer having an ion conductive group in the side chain is 10 to 50% of the total monomers including other monomers.
It is preferable to mix in the range of (% by weight, the same applies hereinafter). The greater the amount of the monomer having an ion conductive group, the better the antistatic effect can be obtained. However, considering the adhesiveness with the base film and the pressure-sensitive adhesive layer, the range of 15 to 30% is particularly preferable. preferable.

This antistatic layer is obtained by adding the above copolymer to water, methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone,
It can be formed by dissolving or dispersing it in a suitable solvent such as ethyl acetate, toluene, xylene to prepare a coating solution, and coating and drying it on one side of the substrate film by a conventional method. As a coating method, a gravure coater, a roll coater,
A conventional coating method such as a wire bar may be used. As the coating amount of the coating liquid, the thickness of the antistatic layer formed is about 0.1
The amount is preferably in the range of 5 μm.

As the polymer having such ionic conductivity, for example, Bondip (product name, Konishi Co., Ltd.) commercially available as a two-pack type antistatic adhesive can be used.

For the pressure-sensitive adhesive layer provided on one surface of the antistatic layer, generally used acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives and the like are used. The thickness is preferably in the range of 1 to 10 μm. The coating method is the same as that of the antistatic layer.

In order to improve the releasability from the photoresist, on the surface of the transparent support opposite to the antistatic layer,
A release layer containing a silicone-based release agent may be formed. In this case, it is desirable that the release agent covers about 2 to 15% of the entire coating film. Further, when used for contact exposure, it is effective to add a pigment in order to improve vacuum adhesion. The pigment may be inorganic or organic, and the type thereof is preferably highly transparent resin beads such as acrylic, silicone, polyethylene, and polypropylene so as not to hinder the transparency as much as possible. The thickness may be about 1 to 10 μm. The method of forming the release layer is also the same as that of the antistatic layer.

[0019]

The present invention will be described more specifically with reference to the following examples. In addition, "%" and "part" in this example are based on weight unless otherwise specified.

Example 1 The following coating solution for antistatic layer was applied to one side of a transparent polyester film having a thickness of 6 μm by a bar coater, dried at 80 ° C. for 2 minutes, and then at 40 ° C. for 48 minutes. After time curing, an antistatic layer having a thickness of about 1 μm was formed. When the surface resistance value of the antistatic layer was measured according to JIS-K6911,
It was 4.1 × 10 ⁷ Ω / □.

<Coating liquid for antistatic layer> -Acrylic resin solution (solid content about 30%) 10 parts (Bondip PX base agent: Konishi Co.)-Epoxy resin solution (solid content about 10%) 10 parts (Bondip PX) Hardener: Konishi) ・ Isopropyl alcohol 15 parts ・ Water 5 parts

Next, the following adhesive layer coating liquid was applied onto the antistatic layer with a bar coater and dried at 80 ° C. for 1 minute to form an adhesive layer having a thickness of about 2 μm.

<Coating liquid for pressure-sensitive adhesive layer> 10 parts of acrylic acid ester copolymer (solid content 40%) (Arontack SCL-200: Toagosei Co., Ltd.) 10 parts of toluene 10 parts of ethyl acetate

Then, a 25 μm-thick polyester film (separator) was laminated on the pressure-sensitive adhesive layer using a laminator to prepare a surface protective film.

[Example 2] A release layer having a thickness of about 1 µm was provided by coating and drying the following release layer coating solution on the polyester film opposite to the antistatic layer of Example 1. A surface protective film was prepared in the same manner as in Example 1.

<Release layer coating liquid> Acrylic polyol (solid content 50%) 16 parts (Acridic A-801: Dainippon Ink and Chemicals, Inc.) Isocyanate prepolymer (solid content 75%) 1.5 parts (Bernock D-750: Dainippon Ink and Chemicals, Inc.) ・ Silicone additive 3 parts (Paintat 53: Dow Corning) ・ Toluene 15 parts ・ Methyl ethyl ketone 6 parts

Comparative Example A pressure-sensitive adhesive layer similar to that of Example 1 was formed by the same method without providing an antistatic layer on the polyester film of Example 1, and a separator similar to that of Example 1 was applied. Together, a surface protection film was produced.

An ash adhesion test was conducted on the surface of the transparent polyester film or the surface of the release layer opposite to the antistatic layer to determine whether or not the surface protection films obtained in Examples and Comparative Examples were triboelectrically charged. In the ash adhesion test by triboelectrification, the surface of the coating film was rubbed 10 times with gauze in an environment of 23 ° C. and 50% RH, and the degree of ash adhesion of tobacco was visually evaluated.

Further, a ash adhesion test was performed on the pressure-sensitive adhesive layer of the surface protection film, and a separator was attached to the pressure-sensitive adhesive layer. As for the ash adhesion test by peeling electrification, immediately after peeling the separator with the test piece of 10 cm square, the ash of the cigarette was separated by 1 m.
The presence or absence of ash adhesion was visually evaluated by approaching to m. The results are shown in Table 1. In addition, those with almost no ash were marked with ◯, and those with considerable ash were marked with x.

[0030]

[Table 1]

As is clear from the above results, almost no ash adherence was found on the triboelectric charges of the examples. As for peeling electrification, ash adhesion to the adhesive layer side was not recognized. On the other hand, in the case of the comparative example, both triboelectric charging and peeling charging occurred, and cigarette ash adhered due to the generated static electricity.

As described above, it can be understood that the antistatic effect is exerted through the adhesive layer in the examples. It can also be understood that in triboelectrification, the antistatic effect is exhibited even through the transparent polyester film and the release layer.

[0033]

The surface protective film of the present invention comprises the antistatic layer provided between the transparent support and the pressure-sensitive adhesive layer, so that the antistatic layer is provided on the surface of the base material opposite to the antistatic layer side and the pressure-sensitive adhesive layer. It has a very remarkable effect that the antistatic effect can be imparted to the surface opposite to the antistatic layer side. Therefore, it is not necessary to add an antistatic layer to the adhesive layer itself, whereby an antistatic effect can be imparted to the surface of the adhesive layer without changing its physical properties.
Further, since the antistatic layer is not exposed on the surface, the antistatic effect can be maintained without yellowing even after long-term use.

Claims (2)

[Claims] 1. A surface protective film comprising an antistatic layer and an adhesive layer provided in this order on one surface of a transparent support. 2. The surface protective film according to claim 1, wherein the antistatic layer is made of a polymer having ionic conductivity.