TW201625755A - Surface protection method - Google Patents

Abstract

This surface protection method is a method in which the surface of a member to be protected which is to be heat treated, said member being either an optical member or an electronic member, is protected by a surface protective film, wherein the surface protective film comprises a substrate and an adhesive layer made from an energy-ray curable adhesive composition and provided to one surface of the substrate. The surface protective film is adhered to the surface of the member to be protected, with the adhesive layer interposed therebetween, and after the adhesive layer of the surface protective film adhered to the surface is cured by energy-rays, the member to be protected to which the surface protective film is affixed is heat-treated.

Description

Surface protection method

The present invention relates to a surface protection film which is formed by laminating an adhesive on one surface of a substrate, and is attached to the surface of various optical members or electronic members to protect the surface.

Conventionally, for example, a lens unit, a communication-sensor module, a motor unit such as a vibrator, and the like, such as a unitized optical member or an electronic member, are processed, assembled, inspected, transported, etc., in order to To prevent damage to the surface, sometimes the surface protection film is attached to the exposed surface. The surface protective film is peeled off from the optical member or the electronic member at a point where surface protection is not required.

The optical member or the electronic member may be attached to another member such as a substrate in a state in which a surface protective film is attached, but a thermosetting adhesive may be used during mounting. At this time, the optical member or the electronic member is heated in a state in which the surface protective film is attached in order to cure the adhesive. However, when the surface protective film is placed under high temperature heating, the adhesion is sometimes increased and it is difficult to peel off from the adherend.

Therefore, in the past, it was required that the adhesion performance would not be greatly changed even if heated. In order to meet the required characteristics, for example, in the adhesive layer, an adhesive containing an acrylic copolymer as a main component and containing a nitrogen-containing monomer is used (refer to Patent Document 1).

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-332419

However, although the surface protection film disclosed in Patent Document 1 suppresses the rate of change in the adhesive force, the adhesion is increased to some extent by heating, and the peeling performance after heating cannot be sufficiently improved. Therefore, there is a demand for a surface protection method which can sufficiently improve the peeling performance of the surface protective film while well protecting the surface of the electronic member or the optical member.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a surface protection method which can achieve a good peeling performance of a surface protective film while appropriately protecting a surface of an optical member or an electronic member by a surface protective film. .

The inventors of the present invention conducted intensive investigations and found that an energy ray-curing type adhesive as a surface protective film was used and surface protection was performed. The above problem can be solved by curing the adhesive layer with an energy ray before heating the film, and thus the present invention has been completed.

(1) A surface protection method which is a surface protection method in which a surface of a member to be thermally treated, which is any one of an optical member or an electronic member, is protected by a surface protection film, and the surface protection film has a base a material and an adhesive layer formed on one surface of the substrate and composed of an energy ray-curable adhesive composition, wherein the surface protective film is passed through the adhesive layer and attached to the protected member. On the surface, the adhesive layer of the surface protective film attached to the surface is hardened by an energy ray, and then the protected member to which the surface protective film is attached is heat-treated.

(2) The surface protection method according to (1) above, wherein the surface protective film has an adhesion force before the energy ray irradiation of 1100 to 20000 mN/25 mm, and an adhesion force after the energy ray irradiation is 200 to 1000 mN/25 mm.

(3) The surface protection method according to (1) or (2) above, wherein the surface protective film has an initial adhesion force of less than 10000 mN/25 mm before the energy ray irradiation.

(4) The surface protection method according to any one of (1) to (3) above, wherein the surface protective film has an adhesion increase rate of 1.5 times or less after heating at 80 ° C for one hour after the energy ray irradiation.

(5) The surface protection method according to any one of (1) to (4) above, wherein the energy ray-curable adhesive composition comprises an acrylic Polymer (A).

(6) The surface protection method according to the above (5), wherein the acrylic copolymer (A) is an energy ray-curable acrylic polymer containing an unsaturated group in a side chain.

(7) The surface protection method according to the above (5) or (6), wherein the acrylic copolymer (A) is at least one or two carbon atoms having 5 to 50% by mass of an alkyl group. An alkyl acrylate which does not contain or contains less than 5% by mass of a monomer component of a carboxyl group-containing monomer.

(8) The surface protection method according to any one of the above-mentioned (5), wherein the acrylic copolymer (A) has a carbon number of 30 to 85% by mass of an alkyl group of 3 or more ( The monomer component of the alkyl methacrylate is copolymerized as a copolymer component.

(9) The surface protection method according to any one of (1) to (8) above wherein the energy ray-curable adhesive composition comprises an energy ray polymerizable compound.

(10) The surface protection method according to any one of (1) to (9) above, wherein, in the heat treatment, the member to be protected to which the surface protective film is attached is heated to 80 ° C or higher.

(11) The surface protection method according to any one of (1) to (10) above, wherein the protected member is a photographic module.

(12) A surface protective film for use in attaching an optical member or an electronic member to protect a surface protective film of the surface, comprising a substrate, and being disposed on one side of the substrate, and hardened by an energy ray An adhesive layer composed of a type of adhesive composition, The adhesion force before the energy line irradiation is 1100~20000mN/25mm, and the adhesion force after the energy line irradiation is 200~1000mN/25mm.

In the present invention, the peeling property of the surface protective film can be made good, and the surface of the optical member or the electronic member can be appropriately protected by the surface protective film.

In the following description, the "weight average molecular weight" means a value converted by standard polystyrene measured by a gel permeation chromatography (GPC) method, specifically, according to the method described in the examples. Measured value.

In addition, in the description in this specification, for example, "(meth)acrylate" shows the terms "acrylic ester" and "methacrylate", and other similar terms are the same.

Hereinafter, the present invention will be described in more detail by way of embodiments.

[surface protection method]

The surface protection method according to the present invention is a method of protecting a surface of a member to be thermally treated by any one of an optical member or an electronic member by a method of protecting a surface protective film, comprising a substrate and being disposed on the substrate a surface protective film of an adhesive layer composed of an energy ray-curable adhesive composition attached to the surface of the member to be protected through an adhesive layer To protect the surface. In the method, the adhesive layer of the surface protective film attached to the surface of the member to be protected is cured by energy rays, and then the protected member to which the surface protective film is attached is heat-treated.

In the present invention, the adhesive layer is hardened by the energy ray before the heat treatment, thereby preventing the adhesion of the adhesive layer from becoming strong during heating, and easily peeling off the surface protection from the protected member even after the heat treatment. The film is therefore less likely to cause poor peeling or residual glue. Further, since the surface protective film also has a certain degree of adhesive force after the energy ray irradiation as described later, the protective performance of the surface protective film is not greatly impaired after the energy ray hardening or after the heat treatment. Further, since the surface protective film is attached to the member to be protected with a high adhesion force before the heat treatment, even if, for example, a large vibration or impact is applied to the member to be protected before the heat treatment, the surface protection film can be prevented from being The protective member is inadvertently peeled off to achieve good protection performance.

The surface protection method of the present invention attaches a surface protective film to the surface of the member to be protected to protect the surface of the member to be treated which has been subjected to various treatments. Specifically, the protected member to which the surface protective film is attached (hereinafter also referred to simply as the member with the surface protective film) is processed and attached to other members, and then inspected or transported, the surface protective film, For example, in a series of steps comprising any of these steps, the surface of the optical member or electronic component is protected. Further, in the present invention, the member with the surface protective film is subjected to heat treatment in any of a series of steps, and before the heat treatment, the energy line is irradiated onto the surface protective film from a generally known irradiation device. In order to reduce the adhesion. at this time, The energy line is usually irradiated on the entire adhesive layer.

Further, the energy ray is usually irradiated onto the adhesive layer through the substrate from the substrate side. Further, specific examples of the energy ray include ultraviolet rays, electron beams, and the like, and ultraviolet rays are preferably used.

The heating temperature in the heat treatment is not particularly limited, but is preferably 60 ° C or higher, and particularly preferably 80 ° C or higher. In the present invention, the adhesion of the adhesive polymer is suppressed by the irradiation of the energy ray, and the adhesion of the adhesive polymer is suppressed by crosslinking or hardening to suppress the movability of the adhesive polymer. Therefore, it is possible to prevent the adhesion of the adhesive layer from being increased by heating, and it is not easy to cause peeling failure or residual glue when the surface protective film is peeled off from the protected member. The upper limit of the heating temperature in the heat treatment is not particularly limited, but is usually 200 ° C or lower, preferably 150 ° C or lower. Further, the heating time of the member with the surface protective film at the above heating temperature is usually about 1 to 120 minutes, preferably about 30 to 100 minutes.

Further, in the present invention, the member having the surface protective film is preferably subjected to the above heat treatment in the step of being attached to another member such as a substrate. Specifically, when the member having the surface protective film is attached to another member such as a substrate by a thermosetting adhesive, the heat treatment is preferably performed in order to cure the adhesive.

Furthermore, in the present invention, the member with the surface protective film attached to the surface protective film to cure the adhesive layer before the heat treatment, but the member with the surface protective film is preferably attached thereto. The steps of processing, transporting, inspecting, or mounting to other components before the energy line is irradiated. In the steps before the irradiation of the energy ray, even if the surface protection film is attached The member is subjected to an impact, and the surface protective film is also firmly attached to the member to be protected without peeling or the like, so that the member to be protected can be appropriately protected.

[protected component]

In the present invention, the member to be protected protected by the surface protective film is an optical member or an electronic member. Examples of the optical member or the electronic component include a lens module in which one or two or more lenses and an image sensor such as a CCD or a CMOS are housed in a casing or a package; a plurality of lenses are held in the lens barrel, and the corresponding A lens unit that is housed in a casing or a package; a light-emitting element unit having a light-emitting element such as an LED; a motor unit such as a vibrator; a communication module, a sensor module, and the like. These optical members or electronic members are preferably members that are used by being attached to other members such as a substrate.

The optical member means an optical component having light-sensitive or light-emitting light or light transmission, and examples thereof include a camera module, a lens unit, a light-emitting element unit, and a communication module that transmits or receives an optical signal. A photo sensor module or the like is a specific example of an optical member. In addition, the electronic component generally includes an electronic component including at least a part of a circuit and transmitting or receiving an electric signal, an electronic component for processing a telecommunication signal, and an electronic component operated by a telecommunication signal or electric power. For example, a motor unit such as a photographing module, a light-emitting element unit, and a vibrator, a communication module that transmits or receives an electric signal, various sensor modules, and the like can be cited as specific examples of the electronic component. The communication module or the light sensor module, the photographic module, and the illuminating element unit that transmit or receive the optical signal are usually components that are both electronic components and optical components.

Further, the optical member or the electronic member is preferably, for example, the above-described electronic component or optical component housed inside the package or the case, or supported by the support member. In addition, a portion of the electronic component or optical component is preferably exposed on the surface, and the surface protective film is used, for example, to protect the exposed component.

Further, among the surface protective films, among them, it is preferable to protect the photographic module. The photographing module is usually provided with light for receiving light from the outside, and is guided to the light receiving portion of the photographing element through a lens inside the module. The light receiving portion is provided on a part (for example, the center) of one surface of the photographing module, and is made of glass or a transparent resin. Preferably, the surface protective film is attached to one surface of the light receiving unit and attached to the image forming unit so as to cover the light receiving portion. Since the surface protective film is attached to the surface of the casing or the package around the light receiving portion and the light receiving portion with a high adhesive force, the light receiving portion provided on one surface of the image pickup module can be appropriately protected.

[surface protection film]

Next, the surface protective film used in the present invention will be described.

In the surface protection film of the present invention, the adhesion force before the energy ray irradiation is preferably 1100 to 20000 mN/25 mm, and the adhesion force after the energy ray irradiation is preferably 200 to 1000 mN/25 mm.

In the present invention, by setting the adhesive force before the energy ray irradiation to 1100 mN/25 mm or more, the adhesion of the surface protective film to the optical member or the electronic member can be improved, and the protective performance can be improved. In addition, by setting it to 20000 mN/25 mm or less, it is easy to make the sticky line after the energy ray irradiation. Focus on becoming the desired size. From this point of view, the adhesion force before the energy ray irradiation is particularly preferably 4000 to 16000 mN/25 mm. The adhesive force before the irradiation of the energy ray can be adjusted by the type of the monomer constituting the adhesive component such as the alkyl (meth) acrylate or the like, the ratio of the crosslinking agent, and the like.

Further, by setting the adhesive force after the irradiation of the energy ray to 200 mN/25 mm or more, the surface protective film may be attached to the member to be protected by a certain degree of adhesion after the irradiation of the energy ray. Therefore, in the present invention, after the energy ray is irradiated, the surface protective film can be protected from the protective member for a certain period of time after the adhesive member is lowered, and the protective performance can be favorably maintained. Further, by setting the adhesive force after the energy ray irradiation to 1000 mN/25 mm or less, the surface protective film can be peeled off from the member to be protected with a relatively small peeling force after the energy ray irradiation. From these points of view, the adhesion layer of the adhesive layer is preferably 250 to 850 mN/25 mm after the irradiation of the energy ray. The adhesive force after the energy ray irradiation can be controlled by the kind or amount of the energy ray polymerizable compound (B), the amount of the unsaturated group introduced into the acrylic copolymer or the like, the amount of the functional group monomer, and the like.

Further, the surface protective film is preferably 1.5 times or less, and more preferably 1.4 times or less, after the energy ray is irradiated at 80 ° C for 1 hour. When the adhesion increase rate is suppressed to be low as described above, the change in the adhesive force due to heating can be suppressed after the energy ray irradiation, so that the peeling property at the time of peeling off the surface protective film can be made good. The lower limit of the rate of increase in the adhesion is not particularly limited, and is usually 1.0 or more.

Adhesion increasing rate, for example, as described later, in acrylic adhesive For example, the carboxyl group-containing monomer may be omitted or the content thereof may be suppressed as a functional group monomer, and further, by using a hydroxyl group-containing monomer, the lowering can be suppressed as described above.

In addition, the initial adhesion force before the energy ray of the adhesive layer is preferably less than 10000 mN/25 mm. By setting the initial adhesion to such a relatively low value, it is possible to easily reattach the surface protective film and improve the reworkability. The lower limit of the initial adhesion is not particularly limited, and is usually 500 mN/25 mm or more. The initial adhesion is particularly preferably 3000~9500mN/25mm.

The initial adhesion can be adjusted by the type and ratio of the alkyl (meth)acrylate, the type of the monomer containing the functional group, the compounding ratio, and the amount of the crosslinking agent.

Further, the above-mentioned adhesion force, adhesion rate increase rate, and initial adhesion measurement method are values measured according to the method described in the examples.

Next, each configuration of the surface protective film of the present invention will be described in more detail.

<Adhesive layer>

The adhesive layer is composed of an energy ray-curable adhesive composition. The energy ray-curable adhesive composition is cured by irradiating an energy ray as described above to lower the adhesive force. Examples of the adhesive constituting the energy ray-curable pressure-sensitive adhesive composition include an acrylic pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyoxynylene-based pressure-sensitive adhesive, and a rubber-based pressure-sensitive adhesive.

Energy line hardening adhesive composition, using so-called X The type is preferred. The X-type energy ray-curable adhesive composition is an energy ray-curable one of the main polymers constituting the adhesive component of the adhesive, and is, for example, an unsaturated base in a side chain of the polymer. Further, as the energy ray-curable adhesive composition, a Y-type energy ray-curable adhesive composition can be cited as another preferred embodiment. The Y-type energy ray-curable adhesive composition imparts energy ray hardenability by blending an energy ray polymerizable compound different from the main polymer constituting the adhesive component. Further, the energy ray-curable adhesive composition may be further mixed with an X-ray and a Y-type, that is, in a main polymer having an energy ray-curable composition and an adhesive component, and further compounding another energy ray-curable compound ( Hereinafter, it is referred to as an XY type, and is preferable.

The case of using an acrylic adhesive as an adhesive will be described in more detail below.

When an acrylic adhesive is used as the adhesive, the energy ray-curable adhesive composition is an energy ray-curable adhesive composition containing the acrylic copolymer (A).

The acrylic copolymer (A) is a main polymer constituting an adhesive component. The acrylic copolymer (A) is a copolymer of a monomer component (hereinafter also referred to as "copolymer component") containing an alkyl (meth)acrylate as a main monomer. Examples of the (meth)acrylic acid alkyl esters include those in which the number of carbon atoms of the alkyl group is from 1 to 18, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, and isopropyl (meth)acrylate. N-propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, Ethyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, and the like.

The acrylic copolymer (A) is usually contained in an amount of 50% by mass or more, preferably 50 to 99.8% by mass, more preferably 75 to 99.5% by mass, based on the total amount of the copolymer component. Composition.

Further, the acrylic copolymer (A) preferably contains 30 to 85% by mass of the (meth)acrylic acid having an alkyl group having 3 or more carbon atoms in the alkyl (meth) acrylate in the total amount of the copolymer component. The alkyl ester is used as a copolymer component. When the content of the (meth)acrylic acid alkyl ester having 3 or more carbon atoms in the alkyl group is in this range, it is possible to easily impart appropriate adhesion properties and peeling properties to the surface protective film. From this viewpoint, the content of the alkyl (meth)acrylate having an alkyl group of 3 or more is particularly preferably 40 to 80% by mass, more preferably 45 to 75% by mass.

The alkyl (meth) acrylate having a carbon number of 3 or more is preferably an alkyl (meth) acrylate having an alkyl group having 3 to 8 carbon atoms, and particularly preferably an alkyl group having 4 to 4 carbon atoms. The alkyl (meth) acrylate is more preferably an alkyl acrylate having an alkyl group having 4 to 8 carbon atoms. Specifically, n-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate or the like is preferred.

Further, the acrylic copolymer (A) preferably contains, as a copolymer component, an alkyl (meth)acrylate having an alkyl group having 1 or 2 carbon atoms. In this case, the alkyl (meth)acrylate having an alkyl group having 1 or 2 carbon atoms is preferably 5 to 50% by mass based on the total amount of the copolymer component. It is 10 to 40% by mass, more preferably 15 to 35% by mass.

As described above, the acrylic copolymer (A) can easily achieve an excellent adhesion or initial adhesion by containing a predetermined low carbon number (meth)acrylic acid alkyl ester as a copolymer component.

The alkyl (meth)acrylate having 1 or 2 carbon atoms of the alkyl group may, for example, be methyl (meth)acrylate or ethyl (meth)acrylate. Among them, methyl acrylate or methyl group is preferred. Methyl acrylate.

The acrylic copolymer (A) preferably contains a polymerizable monomer other than the alkyl (meth)acrylate as a copolymer component, and specifically, preferably contains a functional group-containing monomer. The functional group-containing monomer is a functional group required to bond the unsaturated group-containing compound described later to the acrylic copolymer (A) or to react with a crosslinking agent described later. The monomer having a functional group is a monomer having a polymerizable double bond in the molecule and a functional group such as a hydroxyl group, a carboxyl group, an amine group, a substituted amino group or an epoxy group.

The acrylic copolymer (A) is preferably a copolymerized copolymer component containing 0.2 to 40% by mass of a functional group-containing monomer in the total amount of the copolymer component. By setting the content of the functional group-containing monomer within the above range, the acrylic copolymer (A) can be appropriately crosslinked by a crosslinking agent described later.

Further, the content of the functional group-containing monomer is preferably from 0.2 to 30% by mass, more preferably from 0.5 to 20% by mass. By setting the functional group-containing monomer to such a range, proper adhesion properties can be ensured, and the unsaturated group-containing compound described later can be appropriately introduced into the side chain, and the acrylic copolymer can be made by the crosslinking agent ( A) Crosslink properly.

In addition, for example, in the X type, the content of the functional group-containing monomer is 20% by mass or less as described above, and the amount of the unsaturated group-containing compound is also, for example, 85 equivalents or less as described later. The adhesion force after the energy ray is irradiated reaches a more appropriate value.

The monomer having a functional group, and in the above, a monomer having a hydroxyl group is preferably used. As the hydroxyl group-containing monomer, for example, a hydroxyl group-containing (meth) acrylate can be used. Specific examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. 2-hydroxybutyl acrylate or the like.

The acrylic copolymer (A) preferably contains no carboxyl group-containing monomer, or even if it contains a carboxyl group-containing monomer, the content is less than 5% by mass based on the total amount of the copolymer component, and is used as a copolymer component. By setting the carboxyl group-containing monomer to less than 5% by mass, the adhesive layer can maintain the adhesive strength or initial adhesion after the irradiation of the energy ray at an appropriate value, and the peeling performance or the reworkability can be easily improved.

From such a viewpoint, the content of the carboxyl group-containing monomer of the copolymer component is preferably less than 3% by mass, particularly preferably less than 1% by mass, and further preferably, the carboxyl group-free monomer is not used as the copolymer. ingredient. Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, and itaconic acid.

The compound containing an unsaturated group may be used alone or in combination of two or more.

The acrylic copolymer (A) may contain, in addition to the above monomers, a (meth)acrylic acid alkyl ester and a functional group-containing monomer. (meth) acrylate, dialkyl (meth) acrylamide, vinyl formate, vinyl acetate, styrene, vinyl acetate or the like is used as a copolymer component. As the (meth) acrylate other than the (meth)acrylic acid alkyl ester and the functional group-containing monomer, an (meth)acrylic acid alkoxyalkyl ester or a (meth)acrylic acid alkoxyalkyl ester can be used. Base) decyl phenoxy ethoxylated polyethylene glycol ester, tetrahydrofuranfuran methacrylate, diacrylate of polyether and acrylic acid ester, and the like.

Further, as the dialkyl (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide or the like can be used. The dialkyl (meth) acrylamide is preferably used when the energy ray-curable adhesive composition is of the X-Y type described later. By using a dialkyl (meth) acrylamide as a constituent monomer, the energy ray-curable acrylic copolymer can be improved with respect to an energy ray polymerizable compound such as a urethane acrylate having a high polarity (B). ) the compatibility.

The weight average molecular weight of the acrylic copolymer is preferably 100,000 or more, particularly preferably 100,000 to 1,500,000, more preferably 150,000 to 1,000,000. Here, the weight average molecular weight of the acrylic copolymer is an acrylic copolymer before the reaction of the compound containing an unsaturated group when the unsaturated group-containing compound is reacted to form an energy ray-curable acrylic polymer.

When the energy ray-curable adhesive composition forming the acrylic pressure-sensitive adhesive is X-type, the acrylic copolymer (A) itself has energy ray curability. Specifically, at least a part of the acrylic copolymer (A) is an energy ray-curable acrylic having a side chain having an unsaturated group. Copolymer. The energy ray-curable acrylic copolymer can be obtained by reacting an unsaturated group-containing compound with an acrylic copolymer obtained by copolymerizing the above copolymer component.

The unsaturated group-containing compound has a substituent which can react with a functional group of a functional group-containing monomer constituting the acrylic copolymer. This substituent differs depending on the kind of the functional group which the functional group monomer has. For example, when the functional group is a hydroxyl group, the substituent is preferably an isocyanate group, an epoxy group or the like. When the functional group is a carboxyl group, the substituent is preferably an isocyanate group, an epoxy group or the like, and the functional group is an amine group or In the case of the substituted amino group, the substituent is preferably an isocyanato group or the like, and when the functional group is an epoxy group, the substituent is preferably a carboxyl group, and among them, an isocyanate group is preferred. The above substituent is contained in one molecule per molecule of the unsaturated group-containing compound.

The unsaturated group-containing compound contains 1 to 5 energy ray-polymerizable carbon-carbon double bonds per molecule, preferably 1 to 2. The energy ray polymerizable carbon-carbon double bond is preferably a (meth) acrylonitrile group. Specific examples of the unsaturated group-containing compound include (meth)acryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, and (meth)acryl decyl isocyanate. Allyl isocyanate, glycidyl (meth)acrylate, (meth)acrylic acid, and the like. Further, examples thereof include an acryl-based monoisocyanate compound obtained by reacting a diisocyanate or a polyisocyanate compound with hydroxyethyl (meth)acrylate; a diisocyanate compound or a polyisocyanate compound, a polyol compound, and An acrylonitrile monoisocyanate compound obtained by the reaction of (meth)acrylic acid hydroxyethyl ester.

Further, as the compound containing an unsaturated group, a polymerizable group-containing polyalkylene oxide compound of the following formula (1) can also be used.

In the formula, R ¹ is hydrogen or a methyl group, preferably a methyl group, and each of R ² to R ^{5 is} independently hydrogen or an alkyl group having 1 to 4 carbon atoms, preferably hydrogen, and n is an integer of 2 or more. It is preferably 2 to 4. There are a plurality of R ² to R ⁵ which may be the same or different from each other. In other words, since n is 2 or more, the polymerizable group-containing polyalkylene oxide compound represented by the above formula (1) contains two or more R ² groups. At this time, there are two or more R ² which may be the same or different from each other. The same applies to R ³ to R ⁵ . NCO represents an isocyanate group.

The amount of the unsaturated group-containing compound is usually about 10 to 100 equivalents based on 100 equivalents of the functional group of the acrylic copolymer, but crosslinking can be suitably carried out by crosslinking agent by lowering the equivalent of the functional group. Therefore, it is preferably used in an amount of 15 to 95 equivalents. In addition, it is particularly preferred to use at a ratio of 20 to 85 equivalents. By setting it as 85 equivalent or less, the number of the unsaturated groups which the acrylic copolymer has can be reduced, and the adhesive force after the energy-beam irradiation is relatively easy to increase. In addition, when the heating is performed after the energy ray irradiation by setting it to 20 equivalent or more, it is easy to suppress the rate of increase of the adhesive force.

As the compound containing an unsaturated group, a compound having a (meth) acrylonitrile group and an isocyanate group is preferably used, and specifically, (meth) propylene oxirane ethyl isocyanate is preferred.

When the energy ray-curable adhesive composition constituting the acrylic adhesive is Y-type, the energy ray-curable adhesive composition is blended with an energy ray polymerizable compound different from the acrylic copolymer (A) (B) ) to give energy line hardenability.

As the energy ray polymerizable compound (B), an energy ray polymerizable oligomer such as an epoxy acrylate ester, an urethane acrylate, a polyester acrylate or a polyether acrylate can be used, or Energy ray polymerizable monomer.

The energy ray polymerizable monomer is a low molecular weight compound having at least two or more photopolymerizable carbon-carbon double bonds in the molecule, and specifically, tris(meth)acrylic acid trihydroxyl can be used. Methylpropane ester, tetrakis (meth) methacrylate, neopentyl (meth) acrylate, neopentyl tetra(meth) acrylate, bis(methyl) acrylate Pentaerythritol monohydroxy ester, dipentaerythritol hexa(meth)acrylate or 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate Wait.

Among these, a urethane acrylate-based oligomer can be preferably used. A urethane acrylate-based oligomer is a compound containing an isocyanate unit and a polyol unit and having a (meth) acrylonitrile group at the terminal. The urethane acrylate-based oligomer may, for example, be a polyhydric alcohol having a hydroxyl group at the end of a polyether polyol or a polyester polyol, and reacted with a polyisocyanate to form an amino group of a terminal isocyanate. An acid ester oligomer, a compound obtained by reacting a compound having a (meth) acrylonitrile group with a functional group at the terminal, and the like. The urethane acrylate is low The polymer has energy ray hardenability by the action of a (meth) acrylonitrile group.

Examples of the polyisocyanate used in the urethane acrylate-based oligomer include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and 1,3-xylene diisocyanate, and 1,4. -xylene diisocyanate, diphenylmethane 4,4-diisocyanate, isophorone diisocyanate, 1,3-bis-(isocyanatomethyl)-cyclohexane, 4,4'-dicyclohexyl Methane diisocyanate and the like. Examples of the compound having a (meth)acryl fluorenyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and polyethylene glycol (meth)acrylate. Hydroxy (meth) acrylate.

Further, examples of the (meth) acrylate having a hydroxyl group include polyhydric alcohols such as pentaerythritol and partial esters of (meth)acrylic acid.

The urethane acrylate oligomer is preferably a bifunctional group having two or more (meth) acryl fluorenyl groups in one molecule. However, when it is not used together with the X type, it is preferably Those having 3 or more functional groups are preferably those having 4 or more functional groups. When a trifunctional group or more is used, it is easy to make an adhesive force after hardening into an appropriate value. Further, it is easy to achieve good peeling performance of the surface protective film after the energy ray irradiation. Further, as the urethane acrylate-based oligomer, a 12-functional group or less is usually used.

Further, the urethane acrylate-based oligomer preferably has a weight average molecular weight of from 1,000 to 15,000, particularly preferably from 1,500 to 8,500.

The energy ray polymerizable compound (B) is usually blended in an amount of 1 to 150 parts by mass based on 100 parts by mass of the acrylic copolymer (A), and is not combined with the X type. When used in combination, it is preferably 20 to 100 parts by mass, particularly preferably 35 to 75 parts by mass. By setting the content of the energy ray polymerizable compound (B) in these ranges, the adhesion of the adhesive layer before and after the irradiation of the energy ray can be appropriately maintained. In addition, when it is 75 parts by mass or less as described above, the adhesive force after the energy ray irradiation can be set relatively high with a relatively small amount of the energy ray polymerizable compound (B), and it is easy to cause the energy ray after irradiation. The protection performance is good. In addition, when it is set to 35 mass parts or more, when it heats after an energy-beam irradiation, it is hard to raise an adhesive force.

In the acrylic adhesive, the energy ray-curable adhesive composition in the XY type may be composed of an energy ray polymerizable compound (B) in addition to the acrylic copolymer (A), and an acrylic copolymer. At least a part of (A) or the like is an energy ray-curable acrylic copolymer having an unsaturated group in a side chain. In the case of the X-Y type, the breaking strength and the elongation at break of the adhesive layer can be made good, and the residual adhesive to the adherend can be easily reduced when the surface protective film is peeled off.

The energy ray-curable acrylic copolymer used in the X-Y type can be used in the same manner as the user of the above X type.

Further, the energy ray polymerizable compound (B) may be the same as those used in the above Y type, and is preferably a urethane acrylate oligomer. In this case, a polyisocyanate is particularly preferable. Isophorone diisocyanate, 1,3-bis-(isocyanatomethyl)-cyclohexane, 4,4'-dicyclohexylmethane diisocyanate or the like. Further, as the polyol forming the polyol unit in the urethane acrylate, polypropylene glycol (PPG), polyethylene glycol (PEG), polytetramethylene glycol, polycarbonate diol, etc. are preferably used. , these The number average molecular weight of the polyol is preferably from 300 to 2,000, particularly preferably from 500 to 1,000.

Further, in order to improve the breaking strength and elongation at break of the pressure-sensitive adhesive layer, the polyol preferably contains two or more kinds of polyols, and the polyol preferably contains PPG and PEG, and is preferably only composed of PPG and PEG. Composition. The molar ratio of PPG to PEG is preferably from 9:1 to 1:9, more preferably from 9:1 to 1:4, more preferably from 4:1 to 3:2, and most preferably from 7.5:2.5 to 6.5: 3.5.

Further, the urethane acrylate oligomer in the X-Y type is preferably a 2-functional group having two (meth) acrylonitrile groups in one molecule. By using a 2-functional group, the peeling property or the adhesiveness can be made good, and the breaking strength and the elongation at break can be easily improved.

In the X-Y type, the energy ray polymerizable compound (B) is preferably from 1 to 50 parts by mass, particularly preferably from 5 to 30 parts by mass, per 100 parts by mass of the acrylic copolymer (A).

The adhesive layer may have a crosslinked structure in which the main polymer of the acrylic copolymer (A) or the like is crosslinked. The crosslinking agent (C) to be crosslinked and contained in the energy ray-curable adhesive composition may, for example, be an organic polyvalent isocyanate compound, an organic polyvalent epoxy compound or an organic polyvalent imine compound. It is preferably an organic polyvalent isocyanate compound (isocyanate crosslinking agent).

Examples of the organic polyvalent isocyanate compound include an aromatic polyvalent isocyanate compound, an aliphatic polyvalent isocyanate compound, an alicyclic polyvalent isocyanate compound, and a terpolymer of these organic polyvalent isocyanate compounds, and organic polyvalents thereof. Isocyanate compound and polyolization The terminal isocyanate urethane prepolymer obtained by the reaction of the compound, and the like.

More specific examples of the organic polyvalent isocyanate compound include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylene diisocyanate, 1,4-dimethylbenzene diisocyanate, and diphenyl. Methane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, bicyclo Hexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, adduct of toluene diisocyanate and trimethylolpropane, and the like.

Specific examples of the organic polyvalent epoxy compound include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl Alkyl xylene diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidylamine, and the like.

Specific examples of the organic polyvalent imine compound include N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxyguanamine), trimethylolpropane-tri-β- Aziridine propionate, tetramethylolmethane-tri-beta-aziridine propionate and N,N'-toluene-2,4-bis(1-aziridinecarboxylamine) tri-ethylene melamine Wait.

The content of the crosslinking agent (C) is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, even more preferably 0.5 to 0.5 parts by mass based on 100 parts by mass of the main polymer such as the acrylic copolymer (A). The ratio of 8 parts by mass is used. When the content of the crosslinking agent (C) is at most the above upper limit value, the adhesive layer can be prevented from being excessively crosslinked, and an appropriate adhesion can be easily obtained. In addition, When the amount of the crosslinking agent is at least the above lower limit value, it is possible to prevent the adhesive from remaining in the electronic member or the optical member.

The energy ray-curable adhesive composition preferably contains a photopolymerization initiator (D).

The photopolymerization initiator may, for example, be a photopolymerization initiator such as a benzoin compound, an acetophenone compound, a mercaptophosphine oxide compound, a titanocene compound, a thioxanthone compound or a peroxide compound, or an amine or Specific examples of the light sensitizer and the like include 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl diphenyl sulfide, and the like. Kethiram monosulfide, azobisisobutyronitrile, dibenzyl, diethylidene, β-chloropurine, 2,4,6-trimethylbenzhydryldiphenylphosphine oxide, etc. . By adjusting the photopolymerization initiator (D), the irradiation time and the amount of irradiation of the energy line for hardening can be reduced.

The content of the photopolymerization initiator (D) is not particularly limited, and is preferably 0.1 to 10 parts by mass, particularly preferably 1 to 5 parts by mass, per 100 parts by mass of the main polymer such as the acrylic copolymer (A). .

Further, the adhesive layer may be colored in such a manner that the light transmittance of the surface protective film is less than 50%. In the adhesive layer, since the visibility of the surface protective film can be improved by coloring, for example, the surface protective film can be easily peeled off from the release sheet described later by a human hand. The light transmittance of the surface protective film was measured at a wavelength of 600 nm by a spectrophotometer UV-3600 manufactured by Shimadzu Corporation. The above light transmittance is preferably about 10 to 40%.

In order to color the adhesive layer, the adhesive composition usually contains dyeing Among the materials and pigments, it is preferred to contain a blue dye or a blue pigment.

Further, the energy ray-curable pressure-sensitive adhesive composition may suitably contain components other than the above-described components such as an anti-deterioration agent, an anti-charge agent, a flame retardant, a polyoxymethylene compound, and a chain transfer agent.

The thickness of the adhesive layer is not particularly limited, and is preferably from 3 to 50 μm, particularly preferably from 5 to 30 μm. By setting the thickness of the adhesive layer to the above range, the adhesion to the adherend can be easily improved.

Further, the surface protective film may partially deposit the adhesive layer on the substrate, and form a non-adhesive portion on the substrate together with the adhesive portion. When a surface protective film partially provided with an adhesive layer is produced, screen printing or ink jet printing can be performed. The adhesive portion and the non-adhesive portion are preferably selected from the group consisting of a strip shape, a square shape, a dot shape, a shape in which a plurality of wave lines are arranged, a checkerboard pattern, and a shape in which a plurality of patterns are arranged. Configuration, can also be other shapes.

When the adhesive layer is partially disposed in a pattern, the pattern is usually disposed on the entire surface of the substrate.

Furthermore, in each pattern, the pitch of the pattern (that is, the interval between adjacent adhesive portions or the interval between adjacent non-adhesive portions) is preferably 10 to 500 μm, and particularly preferably 10~300μm, especially 10~250μm.

That is, the width of each strip and the interval of the strips, the width of each wave line, the spacing between the wave line and the wave line, the width of each line forming the square, and the line between the adjacent lines forming the square The interval, the interval between the dots, the width and height of the dots, and the height and width of each of the squares constituting the checkerboard pattern are preferably 10 to 500 μm, particularly preferably 10 to 300 μm, and particularly preferably 10 to 250 μm.

Further, the surface protective film may be irradiated with an energy ray in advance to be hardened by a part of the adhesive layer before being applied to the surface of the member to be protected. When a part of the adhesive layer is partially hardened by the irradiation of the energy ray, the surface protective film is adhered to the surface of the surface of the member to be protected, and has a strong adhesive portion in which the energy is not irradiated and the adhesive force is high. And the energy line is irradiated to harden so that the adhesion is lower than the weak adhesion of the strong adhesion portion.

The strong adhesive portion and the weak adhesive portion are the same as the adhesive portion and the non-adhesive portion, and are preferably configured in a pattern shape. The details of the pattern of the strong adhesive portion and the weak adhesive portion are the same as those of the adhesive portion and the non-adhesive portion, and the description is omitted here.

The partial hardening of the pressure-sensitive adhesive layer is not particularly limited, and for example, a mask that transmits an opening having a shape conforming to a weakly adhering portion, or a light-shielding member having a light-shielding portion having a shape conforming to a strong adhesive portion is generally used. The known irradiation device performs irradiation of an energy ray on the adhesive layer. The energy ray may be irradiated to the adhesive layer from the substrate side through the substrate, or may be irradiated from the opposite side of the substrate.

The surface protection film is provided with an adhesive portion and a non-adhesive portion or a strong adhesive portion and a weak adhesive portion, and the ratio of the area of the adhesive portion to the non-adhesive portion or the ratio of the area of the strong adhesive portion to the weakly adhesive portion is appropriately adjusted. Adjust the adhesion of the surface protection film appropriately.

In the present invention, even if the adhesive layer is partially provided, or the adhesive layer is partially hardened, as described above, the surface protective film adhered to the surface of the member to be protected is adhered by the energy ray before the heat treatment. Hard layer The entire layer of the adhesive layer is hardened.

<Substrate>

The material of the substrate is not particularly limited, and a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a poly pair can be used. Ethylene phthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionic polymer resin film, ethylene-(meth)acrylic copolymer film, poly A film of a styrene film, a polycarbonate film, a fluororesin film or the like. Further, a crosslinked film or a laminated film can be obtained for this purpose.

In addition, the substrate must have permeability relative to the wavelength of the energy line used. That is, when ultraviolet rays are used as the energy ray, the substrate is a light permeable film. Further, when an electron beam is used as the energy ray, the substrate does not have to be light-transmitting, and a colored film can be used. Further, the thickness of the substrate can be adjusted depending on the performance required for the surface protective film, and is preferably 10 to 300 μm, particularly preferably 30 to 150 μm.

The film area of the surface protective film is preferably 100 mm ² or less, and particularly preferably about 10 to 80 mm ² . The surface protective film is reduced in size in response to the optical member and the electronic member. However, as described above, since the peeling performance is good, even if the size is small, it is easy to peel off by hand. Further, the shape of the surface protective film is not particularly limited, and for example, it can be processed into a circular shape, a circular shape, a square shape, a rectangular shape or the like.

Adhesive layer side of the surface protection film, can be attached to the peeling thin The sheets are protected with a release sheet. The release sheet can be applied to a peeling agent such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene or the like by a release agent such as a polyoxymethylene resin. Etc., but not limited to this. The surface protective film may be provided in plural on one peeling sheet which is much larger than the size of the surface protective film.

The method of forming the pressure-sensitive adhesive layer is not particularly limited, and the energy ray-curable pressure-sensitive adhesive composition which is diluted with a suitable solvent is applied to the release sheet so as to have a predetermined dry film thickness, and then dried. After the adhesive layer is formed, the substrate is bonded to the adhesive layer to form.

Further, an energy ray-curable adhesive composition which is diluted with a suitable solvent as necessary may be directly applied onto a substrate and then dried to form an adhesive layer. The release sheet can be further attached to the adhesive layer.

Further, the through process can be performed before or after the formation of the adhesive layer. The through processing can be performed, for example, on a laminate of a substrate and an adhesive layer provided on the release sheet, and the shape of the surface protection film can be formed into a circular shape or the like as described above. Further, the unevenness can be appropriately formed on the surface protective film by molding or the like at an arbitrary timing.

[Examples]

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

The measurement method and evaluation method in the present invention are as follows.

[weight average molecular weight (Mw)]

The measurement was carried out under the following conditions using a gel permeation chromatography apparatus, and the value measured by standard polystyrene conversion was used.

(measurement conditions)

Measuring device: product name "HLC-8220GPC", manufactured by Tosoh Corporation

Column: Product name "TSKGel SuperHZM-M", manufactured by Tosoh Corporation

Developing solvent: tetrahydrofuran

Column temperature: 40 ° C

Flow rate: 1.0mL/min

[adhesion]

The surface protective film was cut into a width of 25 mm to form a sample, and attached to a mirror surface of the wafer as the adherend by a 2 kg roller in an environment of 23 ° C and 50% relative humidity. After allowing to stand in an environment of 23° C. and 50% relative humidity for 20 minutes, the adhesion at the time of peeling at a tensile speed of 300 mm/min and 180° was measured, and the adhesion force before the energy ray irradiation was measured. Further, after standing at 23 ° C and 50% relative humidity for 20 minutes, ultraviolet rays were irradiated under a nitrogen atmosphere using an ultraviolet irradiation device (RAD-2000 m/12 manufactured by Lintec Co., Ltd.) (illuminance 230 mW/cm ^{2 )} The amount of light is 190 mJ/cm ² ). The sample attached to the silicon wafer. Then, the adhesion at the stretching rate of 300 mm/min and 180° was measured under an environment of 23° C. and 50% relative humidity, and the adhesion was made after the energy ray irradiation.

[Adhesion and adhesion increase rate after heating]

The surface protective film was cut into a width of 25 mm to form a sample, and attached to a mirror surface of the wafer as the adherend by a 2 kg roller in an environment of 23 ° C and 50% relative humidity. After standing for 20 minutes, using an ultraviolet irradiation apparatus (made of Lintec Co. RAD-2000m / 12), under a nitrogen atmosphere in a UV irradiation (illuminance 230mW / cm ^2, light quantity of 190mJ / cm ²⁾ attached to the silicon wafer Sample. Then, it was placed in an oven at 80 ° C for 1 hour, and then returned to an environment of 23 ° C and 50% relative humidity. After 20 minutes, the adhesion of the surface protective film at a tensile speed of 300 mm/min and 180° was measured. Force, and the measured value is set as the adhesion after heating.

Further, the adhesion growth rate (B/A) of the ratio of the adhesion (B) after heating to the adhesion (A) after the above-described measured energy ray irradiation was calculated.

[initial adhesion]

The adhesive sheet was cut into a width of 25 mm to form a sample, and attached to a mirror surface of the wafer as the adherend by a 2 kg roller in an environment of 23 ° C and 50% relative humidity. Shortly after attachment (within 1 minute), the adhesion at a tensile speed of 300 mm/min and 180° was measured at 23 ° C and 50% relative humidity, and the adhesive force was set to Initial adhesion.

〔evaluation method〕

<reworkability>

The reworkability when the surface protective film obtained in each of the examples and the comparative examples and which was not subjected to heat treatment and ultraviolet irradiation was attached to the adherend, and then reattached was evaluated by the following evaluation criteria.

A: It is easy to reattach the surface protective film and has good reworkability.

B: When the surface protective film is attached to the adherend, it is difficult to reattach and the reworkability is insufficient.

<Protection>

The protective properties of the surface protective films of the respective examples and comparative examples were evaluated by the following evaluation criteria.

A: The surface protective film is excellent in adhesion to the adherend at all stages, and is excellent in protective properties.

B: Before the irradiation of the energy ray, the surface protective film has good adhesion to the adherend, but after the energy ray is irradiated, the adhesion is insufficient, and the surface protective film is inadvertently peeled off.

C: Before and after the irradiation of the energy ray, the adhesion of the surface protective film to the photographic module is low, and the surface protective film is inadvertently peeled off.

<Peeling>

The peeling property at the time of peeling the surface protection film from the adhering body in each Example and the comparative example was evaluated by the following evaluation criteria.

A: The surface protective film was easily peeled off, and when visually observed, no residual glue was observed on the adherend.

B: Although no residual glue was observed in the attached body, the peeling resistance was relatively high when the surface protective film was peeled off, and it took time to perform peeling by hand.

C: When the surface protective film was peeled off, the peeling resistance was high, and it took time to peel off by a manual operation, and when visually observed, the residual glue was observed on the adherend.

[Example 1]

In an ethyl acetate solvent, 69.5 parts by mass of n-butyl acrylate, 30 parts by mass of methyl acrylate, and 0.5 parts by mass of 2-hydroxyethyl acrylate were polymerized to obtain an acrylic copolymer having a weight average molecular weight of 460,000. Then, 100 parts by mass (in terms of solid content) of the acrylic copolymer diluted with the ethyl acetate solvent and a pentaerythritol-based 5-nonfunctional urethane acrylate oligomer 60 having a weight average molecular weight of 2,300 were mixed. 2.0 parts by mass of Irgacure 184 (manufactured by BASF Corporation) as a photopolymerization initiator, and 8 parts by mass of an organic polyvalent isocyanate compound (product name "BHS8515", manufactured by Toyochem Co., Ltd.) as a crosslinking agent, and An ethyl acetate dilution of the energy ray-curable adhesive composition (Y type) was obtained. The diluted solution was applied to a substrate composed of a polyethylene terephthalate film having a thickness of 50 μm so as to have a thickness of 20 μm after drying, and then dried by heating at 100 ° C for 1 minute to form a substrate. Adhesive layer to obtain a surface protective film.

Then, the release sheet was further superposed on the adhesive layer of the surface protective film, and the surface protective film was processed into a circular shape having a diameter of 5 mm (area: 19.6 mm ² ). After bonding the surface protective film after the through-hole processing to the image forming module of the adherend, the ultraviolet ray irradiation device (RAD-2000m/12, manufactured by Lintec Co., Ltd.) was used to irradiate the ultraviolet ray under a nitrogen atmosphere (illuminance 230 mW/ Cm ² , light quantity 190 mJ/cm ² ) Surface protection film. Then, the adherend to which the surface protective film was attached was heated at 80 ° C for 1 hour to heat-treat, and then the surface protective film was peeled off.

[Example 2]

65 parts by mass of n-butyl acrylate, 20 parts by mass of methyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate were polymerized in an ethyl acetate solvent to obtain an acrylic copolymer having a weight average molecular weight of 470,000, and then Further, 16 parts by mass of isocyanate methyl methacrylate (MOI) as an unsaturated group-containing compound (80 equivalents per 100 equivalents of 2-hydroxyethyl acrylate) is reacted with the acrylic copolymer 100. An ethyl acetate dilution of an energy ray-curable acrylic copolymer was obtained in parts by mass. Then, 2.0 parts by mass of Irgacure 184 (manufactured by BASF Corporation) as a photopolymerization initiator, and 1 part by mass of an organic polyvalent isocyanate compound (product name "BHS8515", manufactured by Toyochem Co., Ltd.) as a crosslinking agent were mixed. A diluted solution of the energy ray-curable adhesive composition (X type) was obtained by 100 parts by mass (in terms of solid content) of the energy ray-curable acrylic copolymer diluted with the ethyl acetate. then It was carried out in the same manner as in Example 1.

[Example 3]

In the same manner as in Example 1, except that the amount of the urethane acrylate oligomer was changed to 120 parts by mass.

[Example 4]

52 parts by mass of n-butyl acrylate, 20 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate were polymerized in an ethyl acetate solvent to obtain an acrylic copolymer having a weight average molecular weight of 500,000. Further, 33.7 parts by mass of isocyanate methyl methacrylate (MOI) as an unsaturated group-containing compound (90 equivalents per 100 equivalents of 2-hydroxyethyl acrylate) is further reacted with the acrylic copolymer 100. An ethyl acetate dilution of an energy ray-curable acrylic copolymer was obtained in parts by mass. Then, 0.3 parts by mass of Irgacure 184 (manufactured by BASF Corporation) as a photopolymerization initiator, and 0.5 parts by mass of an organic polyvalent isocyanate compound (product name "BHS8515", manufactured by Toyochem Co., Ltd.) as a crosslinking agent were mixed. A diluted solution of the energy ray-curable adhesive composition (X type) was obtained by 100 parts by mass (in terms of solid content) of the energy ray-curable acrylic copolymer diluted with the ethyl acetate. Then, it was carried out in the same manner as in Example 1.

[Comparative Example 1]

In Example 2, except that the ultraviolet irradiation was performed after the heat treatment, the same procedure as in Example 2 was carried out, and after the ultraviolet irradiation, the surface protective film was peeled off from the adherend.

The adhesion of the energy rays before and after the irradiation of the above-mentioned examples and comparative examples, the adhesion energy after further heating to 80 ° C (adhesive force after heating), the rate of increase of adhesion, and the determination of initial adhesion The results, as well as the evaluation results of each evaluation test, are shown in Table 1.

From the above results, it was found that in Examples 1 to 4, since the surface protective film was heated after the ultraviolet irradiation, the adhesion was not excessively increased after the heat treatment, and the peeling property was improved. In addition, the initial adhesion is also good, and the reworkability is excellent. Further, in Examples 1 and 2, since the adhesive force after the energy ray irradiation was relatively large, the surface protective film was hardly peeled off at any stage after the heat treatment was performed before and after the irradiation of the energy ray. It has excellent protection performance.

On the other hand, in Comparative Example 1, ultraviolet irradiation was performed after the heat treatment. At the time of shooting, the peeling performance after ultraviolet irradiation is insufficient, and it cannot be used practically.

Claims (11)

A surface protection method, which is a surface protection method for protecting a surface of a member to be thermally treated by any one of an optical member or an electronic member, wherein the surface protection film is provided with a substrate, And the adhesive layer formed of the energy ray-curable adhesive composition on one surface of the substrate, and the surface protective film is attached to the surface of the protected member through the adhesive layer. After the adhesive layer of the surface protective film attached to the surface is hardened by the energy ray, the protected member to which the surface protective film is attached is heat-treated. The surface protection method according to claim 1, wherein the surface protective film has an adhesion force before the energy ray irradiation of 1100 to 20000 mN/25 mm, and an adhesion force after the energy ray irradiation is 200 to 1000 mN/25 mm. The surface protection method according to claim 1 or 2, wherein the surface protective film has an initial adhesion of less than 10000 mN/25 mm before the energy ray irradiation. The surface protection method according to any one of claims 1 to 3, wherein the surface protective film has an adhesion increase rate of 1.5 times or less after heating at 80 ° C for 1 hour after the energy ray irradiation. The surface protection method according to any one of claims 1 to 4, wherein the energy ray-curable adhesive composition comprises an acrylic copolymer (A). The surface protection method according to claim 5, wherein the acrylic copolymer (A) is an energy ray-curable acrylic polymer having an unsaturated group in a side chain. The surface protection method according to claim 5 or 6, wherein the acrylic copolymer (A) is an alkyl (meth)acrylate having at least 5 to 50% by mass of an alkyl group having 1 or 2 carbon atoms; A monomer component which does not contain or contains less than 5% by mass of a monomer having a carboxyl group is copolymerized. The surface protection method according to any one of claims 5 to 7, wherein the acrylic copolymer (A) is an alkyl (meth)acrylate having a carbon number of 30 to 85% by mass of an alkyl group of 3 or more. The monomer component is copolymerized as a copolymer component. The surface protection method according to any one of claims 1 to 8, wherein the energy ray-curable adhesive composition comprises an energy ray polymerizable compound. The surface protection method according to any one of claims 1 to 9, wherein in the heat treatment, the member to be protected to which the surface protective film is attached is heated to 80 ° C or higher. The surface protection method according to any one of claims 1 to 10, wherein the protected member is a photographic module.