TW201630748A - Surface protective film - Google Patents

Abstract

This surface protective film is affixed to an optical member or an electronic member and is used to protect the surface of the optical member or the electronic member, wherein: the surface protective film is provided with a support body having a bending resistance of 5,000-45,000 mNcm, and an adhesive layer on one surface of the support body; the support body has a buffer layer comprising one or more materials selected from buffer layer formation resin films and buffer layer formation compositions containing an energy-beam-polymerizable compound; and when the buffer layer is indented by the tip of a triangular-pyramid-shaped indenter having a tip curvature radius of 100 nm and an inter-ridge angle of 115 DEG at a speed of 10 [mu]m/min, the indentation depth (Z) required for the compression load to reach 2 mN is 2.5 [mu]m or above.

Description

Surface protection film

The present invention relates to a surface protective film in which an adhesive is laminated on one side of a support, and more particularly to a surface protective film which is applied to a surface of various optical members or electronic members to protect the surface thereof.

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, the surface protective film may be attached to the exposed surface. The surface protective film can be peeled off from the optical member or the electronic member at the point of no surface protection.

Further, a substrate of the surface protective film is known, and for example, a polyethylene terephthalate film can be used from the viewpoint of transparency, and from the viewpoint of heat resistance, polyimide or A substrate of polyethylene naphthalate (refer to Patent Document 1).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-341520

In recent years, the optical member or the electronic member has been miniaturized, and accordingly, the size of the surface protective film has been gradually reduced. It has thus become difficult to process the surface protective film to an appropriate size using a through-blade. Therefore, the requirements for improving the processing precision of the surface protective film are gradually increasing.

Further, since the adhesion and peeling of the surface protective film are usually performed by hand, the workability of attaching and peeling is required to be good. Specifically, since the film has a small size, it is likely to be deviated at the time of attachment, and the number of times of reattachment is improved. In order to reduce the number of re-stickings, it is gradually required to improve the ease of attachment. Further, when the surface protective film is difficult to peel off from the adherend, an excessive load is applied to the optical member or the electronic member as the adhering body, which may cause damage to the fine member (causing deformation, damage, and the like). Therefore, the peeling performance of the surface protective film is also required to be good.

However, for example, in Patent Document 1, the workability of the surface protective film, the attachability and the peeling workability are not examined.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a surface protective film for an optical member or an electronic member which is excellent in workability in adhesion and peeling.

The inventors of the present invention conducted intensive studies and found that the surface protective film has a support having a specific bending resistance, and the support has a press-in depth required for a compression load when a predetermined shape of the indenter is pressed to reach 2 mN. The above problem can be solved by a buffer layer having a predetermined value or more, and thus the present invention has been completed.

That is, the present invention provides the following [1] to [12].

[1] A surface protective film for use in a surface protective film attached to an optical member or an electronic member to protect a surface thereof, the film system

a support having a bending resistance of 5000 mN ‧ cm or more and 45000 mN ‧ cm or less; and an adhesive layer on one side of the support body, and

The support system has a buffer layer composed of one or more selected from the group consisting of a buffer layer-forming composition containing an energy ray-polymerizable compound and a resin film for forming a buffer layer, and has a radius of a front end radius of curvature of 100 nm and an inter-edge angle of 115°. The front end of the tapered indenter has a press-in depth (Z) of 2.5 μm or more at a speed of 10 μm /min and a compression load when the buffer layer is pressed into 2 mN.

[2] The surface protection film according to [1] above, wherein the support further has a substrate.

[3] The surface protection film according to [2] above, wherein the support is a support having a resin layer on a surface of the substrate opposite to a surface on which the buffer layer is provided.

[4] The surface protective film according to any one of [1] to [3] above, wherein the front The buffer layer is exposed on the side opposite to the aforementioned adhesive layer.

[5] The surface protection film according to any one of [2] to [4] wherein the substrate is a resin film composed of polyethylene terephthalate.

[6] The surface protection film according to any one of the above [1], wherein the buffer layer forming composition contains a urethane (meth) acrylate (a1) and has a ring formation. The polymerizable compound (a2) having an alicyclic group or a heterocyclic group having 6 to 20 atoms and the polymerizable compound (a3) having a functional group are the above-mentioned energy ray polymerizable compounds.

[7] The surface protection film according to any one of [1] to [6] wherein the resin film for forming a buffer layer is a polyethylene film.

[8] The surface protection film according to any one of [1] to [7] wherein the buffer layer has a thickness of 5 to 100 μm .

[9] The surface protection film according to any one of [1] to [8] wherein the adhesive layer is composed of an energy ray-curable adhesive composition.

[10] The surface protection film according to any one of [1] to [9] wherein the adhesive layer is composed of an energy ray-curable adhesive composition comprising an acrylic copolymer.

The acrylic copolymer is an alkyl (meth)acrylate having at least 5 to 50% by mass of an alkyl group having 1 or 2 carbon atoms, and contains or contains less than 5% by mass of a carboxyl group-containing monomer. The monomer component is copolymerized.

[11] A member having a surface protective film provided with an optical member or an electronic member, and a surface attached to the surface of the optical member or the electronic member as described in any one of the above [1] to [10] Protective film.

[12] A method of protecting a surface of an optical member or an electronic member, The surface protection film according to any one of the above [1] to [10] is attached to the surface.

In the present invention, it is possible to provide a surface protective film for a surface protective film, and an optical member or a surface protective film for an electronic member which is excellent in workability at the time of attachment and peeling.

In the description in the present specification, the term "energy line" means, for example, an ultraviolet ray or an electron beam, and is preferably an ultraviolet ray or an electron beam.

In the description of the present specification, the "weight average molecular weight (Mw)" means a value converted by standard polystyrene measured by a gel permeation chromatography (GPC) method, specifically, The values measured by the methods described in the examples.

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

[Surface protection film]

The surface protective film of the present invention is used for adhering to an optical member or an electronic member to protect the surface thereof, and includes a support and an adhesive layer provided on one surface of the support.

The respective members of the surface protective film will be described below.

<support>

The support body of the surface protective film of the present invention is a support having a buffer layer and has a bending resistance of 5000 mN‧cm or more and 45000 mN‧cm or less.

When a support having a bending resistance of less than 5000 mN·cm is used, when the obtained surface protective film is attached to an optical member or an electronic member, the surface protective film is weak in rigidity and is difficult to attach to a target attached position. And the workability deteriorates.

Further, when a support having a bending resistance of more than 45,000 mN‧cm is used, when the surface protective film attached to the surface of the optical member or the electronic member is peeled off from the surface of the member, it becomes difficult because the hardness of the surface protective film is too strong. Peeling, which deteriorates workability. Further, when the peeling is performed, a load of a required degree or more is applied to the optical member or the electronic member, and the member may be damaged.

In particular, when attaching and peeling work by hand work, it is more difficult to handle a small-sized surface protective film by using an item such as a finger or a tweezers.

From this viewpoint, the bending resistance of the support is preferably 5,500 mN‧cm or more, more preferably 6000 mN‧cm or more, and further preferably 42500 mN·cm or less, and more preferably 40,000 mN·cm or less. The bending resistance is measured by the method according to JIS L 1913, specifically, the value measured and calculated according to the method described in the examples.

In addition, the thickness of the support is not particularly limited as long as the bending resistance of the support is in the above range, and the workability of attaching the surface protective film of the present invention to an optical member or an electronic member and peeling is good. Preferably, it is preferably 30 to 200 μm , more preferably 40 to 200 μm , still more preferably 50 to 150 μm .

(The buffer layer)

The buffer layer of the support body is required to have a front end of a triangular pyramid shaped indenter having a front end curvature radius of 100 nm and an inter-edge angle of 115° at a speed of 10 μm /min, and a compression load of 2 mN when the buffer layer is pressed into the buffer layer. The press-in depth (Z) (hereinafter also referred to as "press-in depth (Z)") is 2.5 μm or more.

The buffer layer is a layer composed of one or more selected from the group consisting of a buffer layer-forming composition containing an energy ray-polymerizable compound and a resin film for forming a buffer layer, and is formed by selecting a buffer layer containing an energy ray-polymerizable compound. The composition of the composition or the selection of the resin film for forming a buffer layer is easy to adjust the depth of penetration (Z) of the buffer layer.

In addition, the buffer layer is preferably a layer composed of one or more selected from the group consisting of a buffer layer forming composition containing an energy ray-polymerizable compound, since it is easy to increase the depth of press-fitting.

Further, the present inventors have found that in the configuration of the surface protective film, the buffer layer having the press-in depth (Z) adjusted to 2.5 μm or more is provided at a position in contact with the penetrating edge during processing. The penetration protection precision of the surface protection film and the size of the surface protection film are properly controlled.

In the surface protective film having the buffer layer having a press-in depth (Z) of less than 2.5 μm , the buffer layer becomes too hard, the through-edge is hard to enter during the through process, or the surface protective film becomes over the through-edge It is difficult to properly control the size of the surface protective film after the processing.

On the other hand, in the surface protective film having the buffer layer having a press-in depth (Z) of 30 μm or less, the buffer layer does not become too soft, and the buffer layer does not adhere to the penetrating edge during the through process. Further, when the penetrating blade is in contact, the buffer layer is not deformed without causing positional displacement of the surface protective film, so that the size of the surface protective film after the through process can be easily and accurately controlled.

From this point of view, the above-mentioned press-in depth (Z) is preferably 2.5 to 30.0 μm , more preferably 5.0 to 25.0 μm , still more preferably 8.0 to 20.0 μm , and particularly preferably 12.0 to 20.0 μm .

Further, in the present invention, the indentation depth (Z) means a value measured by the method described in the examples.

In addition, the indentation depth (Z) can be appropriately changed by changing the kind or content of the component contained in the buffer layer-forming composition containing the energy ray-polymerizable compound forming the buffer layer, the degree of hardening of the buffer layer, and the like. Adjust to the above range. In addition, it is also possible to adjust to the above range by appropriately selecting the raw material resin of the resin film for forming a buffer layer for forming the buffer layer.

In the surface protective film of the present invention, the buffer layer is preferably exposed on the side opposite to the adhesive layer described later.

The energy line contained in the buffer layer forming composition The polymerizable compound is not particularly limited as long as it can form a buffer layer having a press-in depth (Z) in the above range, and for example, a photocurable resin or a monomer can be used.

However, from the viewpoint of adjusting the indentation depth (Z) to the above range, it is preferred to contain a urethane (meth) acrylate (a1), an alicyclic group having a ring-forming atomic number of 6 to 20 or The heterocyclic group polymerizable compound (a2) and the functional group-containing polymerizable compound (a3) are used as a buffer layer forming composition of an energy ray polymerizable compound.

Further, the buffer layer-forming composition preferably contains a photopolymerization initiator, and may contain other additives or resin components within a range not impairing the effects of the present invention.

Each component contained in the buffer layer-forming composition containing the energy ray polymerizable compound will be described below.

[urethane (meth) acrylate (a1)]

The urethane (meth) acrylate (a1) used in the buffer layer-forming composition containing the energy ray-polymerizable compound has at least a (meth) acrylonitrile group and a urethane bond. a compound having the property of being polymerized and hardened by irradiation with an energy ray.

The urethane (meth) acrylate (a1) may be an oligomer, a high molecular weight body, or a mixture of these, preferably a urethane (meth) acrylate. Polymer.

The weight average molecular weight Mw of the component (a1) is preferably from 1,000 to 100,000, particularly preferably from 2,000 to 60,000, more preferably 3,000. 20,000.

Further, the number of (meth)acrylonitrile groups (hereinafter also referred to as "functional group number") in the component (a1) may be monofunctional, bifunctional or trifunctional or higher, preferably monofunctional or bifunctional.

The component (a1) can be obtained, for example, by reacting a (meth) acrylate having a hydroxyl group with a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound with a polyvalent isocyanate compound.

The component (a1) may be used alone or in combination of two or more.

The polyol compound which is a raw material of the component (a1) is not particularly limited as long as it is a compound having two or more hydroxyl groups.

Specific examples of the polyol compound include an alkanediol, a polyether polyol, a polyester polyol, and a polycarbonate polyol.

Among these, a polyester polyol is particularly preferred.

Further, the polyol compound may be a bifunctional diol, a trifunctional triol or a tetrafunctional or higher polyhydric alcohol, preferably a bifunctional diol, more preferably a polyester diol.

Examples of the polyvalent isocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; isophorone diisocyanate and norbornane diisocyanate; An alicyclic diisocyanate such as dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, ω,ω'-diisocyanate dimethylcyclohexane; 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, tolidine diisocyanate, tetramethylene xylene diisocyanate, naphthalene-1,5-diisocyanate An aromatic diisocyanate or the like.

Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylene diisocyanate are preferable.

A urethane (meth) acrylate obtained by reacting a hydroxyl group-containing (meth) acrylate with a terminal isocyanate urethane prepolymer obtained by reacting the above polyol compound with a polyvalent isocyanate compound can obtain a urethane (meth) acrylate. (a1).

The (meth) acrylate having a hydroxyl group is not particularly limited as long as it has at least a hydroxyl group and a (meth) acrylonitrile group in one molecule.

Specific examples of the (meth) acrylate having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, neopentyl tris(meth)acrylate a hydroxyalkyl (meth) acrylate such as an alcohol ester, a polyethylene glycol mono(meth)acrylate, or a polypropylene glycol mono(meth)acrylate; or a N-hydroxymethyl(meth)acrylamide a (meth) acrylamide of a hydroxyl group; a reaction product obtained by reacting (meth)acrylic acid with a diglycidyl ester of vinyl alcohol, vinyl phenol or bisphenol A.

Among these, a hydroxyalkyl (meth) acrylate is preferable, and 2-hydroxyethyl (meth) acrylate is especially preferable.

The conditions for reacting the terminal isocyanate urethane prepolymer and the (meth) acrylate having a hydroxyl group are preferably in accordance with the necessity The reaction is carried out at 60 to 100 ° C for 1 to 4 hours in the presence of a solvent or a catalyst added.

The content of the component (a1) in the buffer layer-forming composition containing the energy ray-polymerizable compound is from the viewpoint of forming a buffer layer having a press-in depth (Z) in the above range, with respect to the buffer layer-forming composition. The total amount (100% by mass) is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, still more preferably 25 to 55% by mass, particularly preferably 30 to 50% by mass.

[Polymerizable compound (a2) having an alicyclic group or a heterocyclic group having a ring number of 6 to 20]

The component (a2) used in the buffer layer-forming composition containing the energy ray-polymerizable compound is a polymerizable compound having an alicyclic group or a heterocyclic group having 6 to 20 ring atoms, and preferably has at least 1 A compound of (meth)acrylonitrile. By using the component (a2), the film formability of the obtained buffer layer-forming composition can be improved.

The ring of the alicyclic group or the heterocyclic group which the component (a2) has is formed to have an atomic number, preferably 6 to 20, more preferably 6 to 18, still more preferably 6 to 16, and particularly preferably 7 to 12.

Examples of the atom forming the ring structure of the heterocyclic group include a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom and the like.

In the present invention, the ring-forming atomic number is a number of atoms constituting the ring itself of a compound in which a ring is bonded to a ring, and an atom not constituting the ring (for example, a hydrogen atom bonded to an atom constituting the ring), Or the The atom contained in the substituent when the ring is substituted by a substituent is not included in the ring to form an atomic number.

Specific examples of the component (a2) include isodecyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentene (meth)acrylate. (A) alicyclic (meth) acrylate such as oxyalkyl ester, cyclohexyl (meth) acrylate, adamantyl (meth) acrylate, tetrahydrofuran (meth) acrylate, morpholine (meth) acrylate A heterocyclic group-containing (meth) acrylate such as an ester.

Further, the component (a2) may be used singly or in combination of two or more.

Among them, a (meth) acrylate containing an alicyclic group is preferred, and an isodecyl (meth) acrylate is more preferred.

The content of the component (a2) in the buffer layer-forming composition containing the energy ray-polymerizable compound is from the viewpoint of forming a buffer layer having a press-in depth (Z) in the above range, and enhancing the obtained buffer layer-forming composition. From the viewpoint of film formability, the total amount (100% by mass) of the composition for forming a buffer layer is preferably from 10 to 70% by mass, more preferably from 20 to 60% by mass, still more preferably from 25 to 55% by mass. %, particularly preferably 30 to 50% by mass.

[Polymerizable compound (a3) having a functional group]

The component (a3) used in the buffer layer-forming composition containing the energy ray-polymerizable compound is a polymerizable compound containing a functional group such as a hydroxyl group, an epoxy group, a decylamino group or an amine group, and preferably has at least 1 (A a compound of an acrylonitrile group.

The component (a3) has good compatibility with the component (a1), and the viscosity of the buffer layer-forming composition can be adjusted to an appropriate range, and the elastic modulus of the buffer layer formed of the composition can also be moderately range. Therefore, by using the component (a3), a buffer layer having a press-in depth (Z) in the above range can be formed.

Examples of the component (a3) include a hydroxyl group-containing (meth) acrylate, an epoxy group-containing (meth) acrylate, a guanamine group-containing compound, and an amine group-containing (meth) acrylate.

Examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and (methyl). 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenylhydroxypropyl (meth)acrylate, and the like.

Examples of the epoxy group-containing (meth) acrylate include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and allyl glycidyl ether.

Examples of the phosphonium group-containing compound include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hydroxyl. (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) propylene Amidoxime and the like.

The amino group-containing (meth) acrylate may, for example, be a (meth) acrylate having a primary amino group and a (meth) acrylate having a secondary amino group. An ester, a (meth) acrylate containing a tertiary amino group, and the like.

Further, examples of the polymerizable compound having another functional group include hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, and N-vinylene. A vinyl compound such as guanamine or the like.

The component (a3) may be used alone or in combination of two or more.

Among these, from the viewpoint of forming a buffer layer having a press-in depth (Z) in the above range, a hydroxyl group-containing (meth) acrylate is preferable, and phenyl hydroxypropyl (meth) acrylate is preferable. A hydroxyl group-containing (meth) acrylate having an aromatic ring.

The content of the component (a3) in the buffer layer-forming composition containing the energy ray-polymerizable compound is from the viewpoint of forming a buffer layer having a press-in depth (Z) in the above range, and enhancing the obtained buffer layer-forming composition. The total amount (100% by mass) of the composition for forming a buffer layer is preferably from 5 to 40% by mass, more preferably from 7 to 35% by mass, still more preferably 10%, from the viewpoint of the film forming property. 30% by mass, particularly preferably 13 to 25% by mass.

Further, the content ratio (a2)/(a3)] (mass ratio) of the component (a2) and the component (a3) contained in the component in the buffer layer forming composition is preferably 0.5 to 3.0, more preferably 1.0~3.0, more preferably 1.3~3.0, especially good 1.5~2.8.

When the content ratio is 0.5 or more, the film forming property of the obtained buffer layer-forming composition can be made good. On the other hand, when the content ratio is 3.0 or less, a buffer layer having a press-in depth (Z) in the above range can be formed.

[Polymerizable compound other than the component (a1) to the component (a3)]

The buffer layer-forming composition containing the energy ray-polymerizable compound may contain other polymerizable compounds other than the above components (a1) to (a3) within a range that does not impair the effects of the present invention.

The other polymerizable compound may, for example, be an alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms; a vinyl compound such as styrene or the like.

These other polymerizable compounds may be used alone or in combination of two or more.

The content of the other polymerizable compound in the buffer layer-forming composition containing the energy ray-polymerizable compound is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, Particularly preferably 0 to 2% by mass.

[Photopolymerization initiator]

In the buffer layer-forming composition containing the energy ray-polymerizable compound, when the buffer layer is formed, it is preferable to further contain a photopolymerization initiation from the viewpoint of shortening the polymerization time by light irradiation and reducing the amount of light irradiation. Agent.

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, an amine or an anthracene. Such as light sensitizers and the like. Specific examples thereof include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, and benzoin. Ether, benzoin ethyl ether, benzoin isopropyl ether, and the like.

These photopolymerization initiators may be used alone or in combination of two or more.

The content of the photopolymerization initiator in the buffer layer-forming composition containing the energy ray-polymerizable compound is preferably 0.05 to 15 parts by mass, more preferably 100 parts by mass based on 100 parts by mass of the total amount of the energy ray polymerizable compound. It is 0.1 to 10 parts by mass, and more preferably 0.3 to 5 parts by mass.

[Other additives and resin components]

Further, the buffer layer-forming composition containing the energy ray-polymerizable compound may contain other additives and resin components within a range that does not impair the effects of the present invention.

Examples of other additives include an antioxidant, a softener (plasticizer), a filler, a rust preventive, a pigment, an antistatic agent, a flame retardant, a dye, and the like.

When the additives are blended, the content of each of the additives in the buffer layer-forming composition is preferably 0.01 to 6 parts by mass, more preferably 0.1 to 3 parts by mass based on 100 parts by mass of the total amount of the energy ray polymerizable compound. Parts by mass.

(Resin film for buffer layer formation)

In addition, the resin film for forming a buffer layer (hereinafter also referred to simply as "the resin film for a buffer layer") is not particularly limited as long as it is a resin film capable of forming a buffer layer having a press-in depth (Z) within the above range. . For example, when the surface protective film after processing is peeled off using an adhesive tape or a heat sealing material, the adhesion from the adhesive tape or the heat sealing material is lifted. From the viewpoint, it is preferred to use a polyethylene film. Examples of the polyethylene resin of the raw material of the polyethylene film include high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE).

The thickness of the buffer layer is not particularly limited as long as the bending resistance of the support is in the above range, and the workability of attaching the surface protective film of the present invention to an optical member or an electronic member and peeling off is good. Preferably, it is preferably 5 to 100 μm , more preferably 10 to 80 μm , and still more preferably 15 to 50 μm .

(substrate)

The support body preferably further has a substrate. When the substrate is provided, the buffer layer is provided on one side of the substrate.

The base material is not particularly limited as long as the bending resistance of the support is in the above range, and is preferably a resin film from the viewpoint of water resistance and heat resistance (hereinafter, simply referred to as "base resin". film").

Examples of the resin constituting the resin film for a base material include polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and wholly aromatic polyester. Polyamide, polyimide, polyacetal, polycarbonate, modified polyphenylene ether, polyphenylene sulfide, polyfluorene, polyether ketone, biaxially oriented polypropylene, and the like.

Among these resins, one or more selected from the group consisting of polyester, polyamine, polyimine, and biaxially oriented polypropylene, and more preferably polyester, more preferably polyethylene terephthalate. ester.

In addition, the base material may be a single-layer film composed of one or more resins selected from the above resins, or a film obtained by laminating two or more of these resin films.

Further, the substrate used in the present invention may contain a filler, a colorant, an antistatic agent, an antioxidant, an organic lubricant, a catalyst, or the like, within a range not impairing the effects of the present invention.

Additionally, the substrate can be transparent or non-transparent or colored as desired. For example, when the buffer layer or the adhesive layer described later contains an energy ray polymerizable compound, it is necessary to have a penetrating property with respect to the wavelength of the energy ray used to cure the energy ray polymerizable compound. 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.

At least one surface of the substrate used in the present invention may be subjected to a subsequent treatment such as corona treatment or an easy-adhesion layer to be described later in order to improve the adhesion to the buffer layer and/or the adhesive layer.

Further, the thickness of the substrate is not particularly limited as long as the bending resistance of the support is in the above range, and may be adjusted according to the performance required for the surface protective film, and is preferably 10 to 300 μm . Very good is 30~150 μ m.

(resin layer)

The support may further have a resin layer on a surface of the substrate opposite to the surface on which the buffer layer is provided.

The resin layer is not particularly limited as long as the bending resistance of the support is in the above range, and for example, the same resin film as the above-mentioned resin film for a buffer layer can be used. From the viewpoint of improving the adhesion to the adhesive layer described later, a polyethylene film is preferred. Examples of the resin of the raw material of the polyethylene film include high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE).

The thickness of the resin layer is not particularly limited as long as the bending resistance of the support is in the above range, and the workability of the surface protective film of the present invention is good when it is attached to an optical member or an electronic member and peeled off. From the viewpoint, it is preferably 5 to 100 μm , more preferably 10 to 80 μm , still more preferably 15 to 50 μm .

<Adhesive layer>

The adhesive for forming the adhesive layer of the surface protective film of the present invention is not particularly limited, and examples thereof include an acrylic adhesive, an urethane-based adhesive, a polyoxygen-based adhesive, and a rubber adhesive. Agent, polyester adhesive.

These adhesives can be used alone or in combination of two or more.

Among the above adhesives, an acrylic adhesive is preferred. Further, in the case of the acrylic pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive (hereinafter also referred to as an acrylic pressure-sensitive adhesive composition) containing the acrylic copolymer (A) is generally used.

The acrylic copolymer (A) is usually an adhesive component in the adhesive layer, and is hereinafter referred to as a main polymer.

In the following description, an acrylic adhesive is mainly used as an example, but the same applies to other adhesives. In this case, a polymer other than the acrylic copolymer (A) is used as the main polymer constituting the 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 having 1 to 18 carbon atoms, 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, (methyl) ) decyl acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, and the like.

The acrylic copolymer (A) is preferably contained in an amount of 50% by mass or more, and particularly preferably 50 to 99.5% by mass of the alkyl (meth)acrylate as a copolymer component, based on the total amount of the copolymer component.

The acrylic copolymer (A) preferably contains 5 to 50% by mass of the alkyl group in the (meth)acrylic acid alkyl ester having 1 to 2 carbon atoms per mole of the copolymer component. An alkyl acrylate is used as a copolymer component. When the content is 5% by mass or more, the adhesion can be suppressed. In particular, when the acrylic adhesive is an energy ray-curable adhesive, the adhesive strength after the energy ray irradiation can be suppressed from being excessively high and the peeling performance can be deteriorated. In addition, the initial adhesion does not become too high, and sufficient reworkability can be obtained. When the content is 50% by mass or less, the adhesion is prevented from being insufficient, and the surface protective film is inadvertently removed from the electronic component in each step described later. And the case where the optical member is peeled off or the electronic member and the optical member are not sufficiently protected.

From the above viewpoints, the acrylic copolymer (A) is more preferably an alkyl (meth) acrylate having 1 to 2 carbon atoms in an amount of 10 to 40% by mass based on the total amount of the copolymer component. The ester is preferably a copolymer component, and more preferably contains 15 to 35% by mass.

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

Further, the acrylic copolymer (A) preferably contains 30 to 85% by mass of the alkyl group in the (meth)acrylic acid alkyl ester having 3 or more carbon atoms (methyl group) based on the total amount of the copolymer component. An alkyl acrylate 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 a carbon number of 3 or more is more preferably 40 to 80% by mass, still 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.

Acrylic copolymer (A), preferably containing (methyl) As the copolymer component, a polymerizable monomer other than the alkyl acrylate is preferably 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.

Here, the acrylic copolymer (A) preferably does not contain a 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. ingredient. By not containing a carboxyl group-containing monomer or lowering the content, the adhesive layer can suppress an excessive rise in the adhesive force after the energy ray irradiation, and the peeling property of the surface protective film can be made good. In addition, excessive increase in initial adhesion is also suppressed, and reworkability is also good.

From such a viewpoint, the content of the carboxyl group-containing monomer of the copolymer component is preferably less than 3% by mass, more preferably less than 1% by mass, and further preferably, the monomer having no carboxyl group is copolymerized. Composition. Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, and itaconic acid.

The above-mentioned functional group-containing monomer is preferably a hydroxyl group-containing compound, and particularly preferably a hydroxyl group-containing (meth) acrylate. The acrylic copolymer (A) preferably copolymerizes a copolymer component containing a hydroxyl group-containing (meth) acrylate in an amount of 0.2 to 40% by mass based on the total amount of the copolymer component. When the content of the hydroxyl group-containing (meth) acrylate is within the above range, the acrylic copolymer (A) can be appropriately crosslinked by a crosslinking agent described later.

Further, the content of the hydroxyl group-containing (meth) acrylate is preferably from 0.3 to 30% by mass, more preferably from 0.5 to 30% by mass. When the hydroxyl group-containing (meth) acrylate is 1 to 30% by mass, proper adhesion performance can be ensured, and the unsaturated group-containing compound described later can be appropriately introduced into the side chain, and the acrylic acid can be made by the crosslinking agent. The copolymer (A) is appropriately crosslinked.

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 above functional group-containing monomers 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) acrylate and a functional group-containing monomer (meth) acrylate or a dialkyl (meth) propylene hydride. An amine, 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, for example, when the adhesive composition is an energy ray-curable adhesive composition and used in the X-Y type described later. By adopting The dialkyl (meth) acrylamide as a constituent monomer can improve the compatibility of the energy ray-curable acrylic copolymer with respect to the energy ray polymerizable compound (B) such as a highly polar urethane acrylate. .

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

Further, the adhesive composition used in the above adhesive layer may be a non-energy hardening type adhesive composition or an energy ray-curable adhesive composition, but is preferably an energy ray-curable adhesive composition.

The energy ray-curable adhesive composition is not particularly limited as long as it has energy ray curability, and a X-type can be preferably used. The X-type energy ray-curable adhesive composition is an energy ray-curable one of the main polymer itself which is an adhesive component constituting the adhesive. For example, in the case of an acrylic adhesive composition, at least a part of the acrylic copolymer obtained by copolymerizing the copolymer component is an energy ray-curable acrylic copolymer having an unsaturated group in a side chain.

The energy ray-curable acrylic copolymer can be obtained by reacting an unsaturated group-containing compound with the above acrylic copolymer.

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 (A). The substituent has a type of functional group possessed by the functional monomer different. For example, when the functional group is a hydroxyl group or a carboxyl group, the substituent is preferably an isocyanate group, an epoxy group or the like, and 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. When the group is substituted or substituted, the substituent is preferably an isocyanate group or the like. When the functional group is an epoxy group, the substituent is preferably a carboxyl group, and among them, an isocyanate group is preferred. The 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 acrylonitrile monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate; a diisocyanate compound or a polyisocyanate compound, a polyol compound, and (a) A acrylonitrile monoisocyanate compound obtained by the reaction of hydroxyethyl acrylate.

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 group 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 unsaturated group-containing compound is usually about 10 to 100 equivalents based on 100 equivalents of the functional group of the acrylic copolymer (A), but can be appropriately crosslinked by a crosslinking agent by lowering the equivalent of the functional group. Preferably, it is preferably used in a ratio of from 15 to 95 equivalents, particularly preferably from about 20 to 90 equivalents.

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.

As the energy ray-curable adhesive composition, a Y-type energy ray-curable adhesive composition can be used as another preferred embodiment. The Y-type energy ray-curable adhesive composition is provided with an energy ray polymerizable compound (B) which is different from the main polymer of the adhesive component constituting the adhesive such as the acrylic copolymer (A). 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-based oligomer 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 and 2,6-toluene. Diisocyanate, 1,3-xylene diisocyanate, 1,4-dimethylbenzene diisocyanate, diphenylmethane 4,4-diisocyanate, isophorone diisocyanate, 1,3-bis-(isocyanate Base) - cyclohexane, 4,4'-dicyclohexylmethane 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 a polyhydric alcohol such as pentaerythritol and a partial ester 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. By using a trifunctional or higher group, the adhesion after the energy ray irradiation is easily reduced, and the peeling performance of the surface protective film is easily improved. 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 5 to 200 parts by mass based on 100 parts by mass of the acrylic copolymer (A) (main polymer), and preferably 40 to 40 parts when not used together with the X type. 200 parts by mass, particularly preferably 70 to 150 parts by mass. By setting the content of the energy ray polymerizable compound (B) in the above range, the adhesion of the adhesive layer before the energy ray irradiation can be appropriately maintained, and the pressure can be appropriately lowered by hardening by the energy ray. Low adhesion.

The energy ray-curable adhesive composition may be a combination of an X-type and a Y-type (hereinafter referred to as an X-Y type). In the acrylic adhesive, the energy ray polymerizable compound (B) is contained in addition to the acrylic copolymer (A), and at least a part of the acrylic copolymer (A) or the like has an unsaturated group in the side chain. The energy ray-curable acrylic copolymer can also be used as a preferred embodiment. By using 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.

For example, 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) used in the XY type may be the same as those used in the above Y type, and is preferably a urethane acrylate oligomer. The polyisocyanate is preferably 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. The number average molecular weight of the polyols 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 9:1 to 1:9, and particularly preferably 9: 1~1:4, more preferably 4:1~3:2, the best is 7.5:2.5~6.5:3.5.

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 XY type, the energy ray polymerizable compound (B) is preferably 1 to 50 parts by mass, particularly preferably 5 to 30 parts by mass, per 100 parts by mass of the acrylic copolymer (A) (main polymer). .

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 adhesive composition may, for example, be an organic polyvalent isocyanate compound, an organic polyvalent epoxy compound or an organic polyimine compound. Among these, organic is preferred. A 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. A urethane prepolymer of a terminal isocyanate obtained by reacting an isocyanate compound with a polyol compound.

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, isophor An ketone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, an 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 polyimine compound include N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxy decylamine), trimethylolpropane-tri-β-nitrogen Propionate propionate, tetramethylolmethane-tri-beta-aziridine propionate and N,N'-toluene-2,4-bis(1-aziridinecarboxylamine) tri-extension melamine .

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, particularly preferably 0.5 to 100 parts by mass based on 100 parts by mass of the acrylic copolymer (A) (main polymer). 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 (C) 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.

Further, the energy ray-curable adhesive composition preferably contains a photopolymerization initiator (D).

The photopolymerization initiator may, for example, be a benzoin compound, an acetophenone compound, a mercaptophosphine oxide compound, a titanocene compound, or a thioxanthone compound. A photopolymerization initiator such as a compound or a peroxide compound, or a photo sensitizer such as an amine or hydrazine, and the like, specifically, for example, 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin methyl ether, Benzoin ethyl ether, benzoin isopropyl ether, benzyl diphenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, dibenzyl, diethylidene, β-chloropurine, 2, 4,6-trimethylbenzimidyldiphenylphosphine oxide or the like. 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 acrylic copolymer (A) (main polymer). .

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 a dye or a pigment, and among them, a blue dye or a blue pigment is preferable.

Further, the above-mentioned adhesive may suitably contain an antioxidant, a softener (plasticizer), an anti-deterioration agent, an antistatic agent, a flame retardant, a rust preventive, a filler, a polyxanthene compound, a decane coupling agent, and a chain. A component other than the above components such as a transfer agent.

In addition, when the above adhesive layer is made of energy line hardening type When the adhesive composition composed of the composition of the composition is used, the adhesion of the surface protective film before the energy ray irradiation is preferably 1000 to 20000 mN/25 mm, and more preferably 4000 to 16000 mN/25 mm. By setting the adhesive force before the energy ray irradiation to 1000 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. Further, by setting it to 20,000 mN/25 mm or less, it is easy to make the adhesive force after the irradiation of the energy ray a desired size. The adhesion before the energy ray irradiation can be adjusted by the type of the alkyl (meth) acrylate, the mixing ratio, the amount of the crosslinking agent, and the like.

Further, the surface protective film preferably has an adhesive force after irradiation with an energy ray of 0.1 to 100 mN/25 mm, particularly preferably 20 to 90 mN/25 mm. Since the adhesive force after the irradiation of the energy ray is in this range, the surface protective film can be easily peeled off from the optical member or the electronic member after the energy ray irradiation.

The adhesive force after the irradiation of the energy ray can be controlled by the kind or amount of the energy ray polymerizable compound (B) and the amount of the unsaturated group introduced into the acrylic copolymer.

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.

Initial adhesion, which can be determined by the type and tone of alkyl (meth)acrylate The ratio, the type of the monomer containing the functional group, the blending ratio, the amount of the crosslinking agent, and the like are adjusted.

Further, the method for measuring the adhesion and initial adhesion is a value measured by the method described below.

[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 tantalum 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.

In addition, the use of 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⁾ to stand for 20 minutes attached to the silicon A sample of the 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.

[initial adhesion]

The surface protective film was cut into a width of 25 mm to form a sample, and attached to a tantalum wafer as a 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 as the initial viscosity. Focus on.

The thickness of the adhesive layer is not particularly limited, and is preferably 3 to 50 μm , particularly preferably 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 cover the adhesive layer on the support and form a non-adhesive portion together with the adhesive portion on the support. 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 support.

Furthermore, in each pattern, the spacing of the patterns (i.e., the spacing between adjacent adhesive portions or the spacing between adjacent non-adhesive portions) is preferably 10 to 500 μm . It is preferably 10~300 μm , especially preferably 10~250 μm .

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, or 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. μ m.

Further, the surface protective film may be irradiated with an energy line in advance to a portion of the adhesive layer before being applied to the surface of the adherend. Chemical. 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 to which the adhering body is attached, and has a strong adhesion in a state where the energy is not irradiated and the adhesive force is high. The part and the irradiated energy line are hardened to make the adhesive force lower than the weakly adhering part of the strong adhesive 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 having an opening having a shape conforming to the weak adhesion portion or a light-shielding member having a light-shielding portion having a shape conforming to the strong adhesion portion is generally used. The known irradiation device performs irradiation of the energy ray on the adhesive layer. The energy ray may be irradiated to the adhesive layer from the support side via the support, or may be irradiated from the opposite side of the support.

Even if the adhesive layer is partially cured, it is preferred to irradiate the surface protective film to the surface protective film attached to the adherend before peeling off the surface protective film from the optical member or the electronic member.

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.

<easy layer>

The support may have an easy-adhesion layer between the substrate and the buffer layer, between the substrate and the resin layer, or both in order to improve the adhesion between the layers of the respective layers.

Further, in order to improve the adhesion between the support and the adhesive layer, it is easy to follow between the surface contacting the adhesive layer (the surface of the support having the resin layer or the substrate) Floor.

The composition for forming an easy-to-adhere layer to form an easy-adhesion layer is not particularly limited, and examples thereof include a polyester resin, a urethane resin, a polyester urethane resin, and an acrylic resin. Composition.

The composition for forming an easy-to-adhere layer may contain a crosslinking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, a rust preventive, a pigment, a dye, or the like, as necessary.

The thickness of the easy-adhesion layer is preferably 0.01 to 10 μm , and particularly preferably 0.03 to 5 μm .

<Peeling sheet>

The adhesive layer side of the surface protective film of the present invention can be attached with a release sheet and protected by a release sheet. A release sheet which has been subjected to double-side peeling treatment, a release sheet which has been subjected to one-side peeling treatment, or the like can be used, and a release agent is applied to the surface of the substrate for release sheet.

The base material for peeling off the sheet, preferably a resin film, and a resin constituting the resin film, and examples thereof include polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate. A polyester resin film such as a resin, a polyolefin resin such as a polypropylene resin or a polyethylene resin, or the like.

Examples of the release agent include a rubber-based elastomer such as a polyfluorene-based resin, an olefin-based resin, an isoprene-based resin, and a butadiene-based resin, a long-chain alkyl resin, an alkyd resin, and a fluorine-based resin. Resin, etc.

The thickness of the release sheet is not particularly limited, and is preferably 10 to 200 μm , particularly preferably 20 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 made smaller in size in response to the optical member and the electronic member. In general, when the film size becomes small, it is difficult to perform attachment or peeling work. As described above, the surface protective film of the present invention is easily peeled off by hand because of its good peeling performance. 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.

When the surface protective film is processed into a predetermined film area and a predetermined shape, as described later, the through process is usually performed.

<Method for Producing Surface Protective Film>

The method for producing the surface protective film of the present invention is not particularly limited, and it can be produced by a generally known method.

For example, it is produced by bonding a buffer layer provided on the release sheet and an adhesive layer provided on the release sheet to each surface of both sides of the substrate. Further, a buffer layer may be directly provided on the surface of the substrate to form a support, and an adhesive layer may be provided on the support.

Further, it may be produced by laminating a buffer layer provided on the release sheet and an adhesive layer provided on the release sheet.

A method of forming a buffer layer on a release sheet or a substrate can be carried out by applying a composition for forming a buffer layer to a release sheet or a substrate by a generally known coating method to form a coating film. Further, the buffer layer can be formed by drying and/or illuminating the coating film.

Examples of the coating method include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a sheet coating method, a die coating method, a gravure coating method, and the like. .

In addition, in order to improve the coating property, an organic solvent may be prepared for the buffer layer-forming composition or the material of the buffer layer-forming resin film, and applied to the release sheet in the form of a solvent.

Examples of the organic solvent to be used include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol.

As the organic solvent, an organic solvent used in the synthesis of each component contained in the composition or an organic solvent of one or more kinds other than the above may be used as it is.

When the buffer layer forming composition for forming a coating film is a buffer layer forming composition containing an energy ray-polymerizable compound, the coating film can be cured by irradiating an energy ray to form a buffer layer.

The hardening treatment of the buffer layer can be completely cured at one time or hardened in plural times. That is, the coating film on the release sheet is completely cured to form a buffer layer, and then bonded to the substrate, or the coating film is not completely cured, but a buffer layer forming film in a semi-hardened state is formed. After bonding the buffer layer forming film to the substrate, the energy line is irradiated again to completely harden the shape. As a buffer layer.

Alternatively, the coating film is not completely cured on the substrate, but a buffer layer forming film in a semi-hardened state is formed, and then the energy ray is irradiated again to be completely cured to form a buffer layer.

The energy ray irradiated in the hardening treatment is preferably ultraviolet ray.

The amount of irradiation of the energy ray is appropriately changed depending on the type of the energy ray. For example, when ultraviolet rays are used, the illuminance of the ultraviolet ray to be irradiated is preferably 50 to 500 mW/cm ² , more preferably 100 to 340 mW/cm ² , and the irradiation amount of ultraviolet rays is preferably 80 to 2500 mJ/cm ² , which is particularly preferable. It is 100~2000mJ/cm ² .

Further, when a resin film for forming a buffer layer is used as the buffer layer, a buffer layer can be formed by a general extrusion lamination process in addition to the above coating method. In addition, a resin film for forming a buffer layer formed in advance may be bonded to a resin film for a substrate by using an adhesive.

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 an appropriate 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 or the support is bonded to the adhesive layer to form. Further, the energy ray-curable adhesive composition which is diluted with a suitable solvent may be directly applied to a substrate or a support, and then dried to form an adhesive layer.

Further, when the surface protective film is processed into a predetermined film area, it is sometimes mainly processed using a penetrating blade (through process). The through process is usually such that the through blade is provided from the support body The face of the adhesive layer enters the face on the opposite side (that is, the face provided with the buffer layer). By using the surface protective film of the present invention, since the buffer layer is present on the surface of the surface protective film on which the penetrating blade is pressed, the sliding of the penetrating blade generated during the through processing can be suppressed, and the processing can be improved. Precision. Through-cut processing can be performed, for example, on the laminate of the adhesive layer and the support formed on the release sheet. By this through processing, the shape of the surface protective film can be formed into a predetermined shape such as a circle as described above.

Further, the unevenness can be appropriately formed on the surface protective film by molding or the like at an arbitrary timing.

[Optical member or electronic member]

The optical member or the electronic component protected by the surface protection film of the present invention includes one or two or more lenses and a photographic module in which a video sensor such as a CCD or a CMOS is housed in a housing or a package; a lens unit that is held in a lens barrel and that is required to be housed in a frame 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, etc. . 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. Further, the electronic component is usually exemplified by at least a constituent circuit. Some of the electronic components that transmit or receive electrical signals, electronic components that process electrical signals, electronic components that operate by electrical signals or electric power, and the like, such as a photography module, a light-emitting component unit, a vibrator, etc. A motor unit, a communication module that transmits or receives a telecommunication signal, various sensor modules, and the like are specific examples of electronic components. 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, for example, the above-described electronic component or optical component is preferably housed inside the package or the frame or supported by the support member. In addition, a portion of the electronic component or optical component is preferably exposed to the surface, and the surface protective film is used, for example, to protect the exposed component.

[How to use the surface protective film]

The surface protective film of the present invention is used for attaching to a surface of an optical member or an electronic member to protect the surface thereof. Specifically, an optical member or an electronic member (hereinafter simply referred to as a member with a surface protective film attached) to which a surface protective film is attached is processed, attached to another member, and then inspected or transported. The surface protective film, in these steps, protects the surface of the optical member or the electronic member. Further, after the surface protective film is finished, the surface protective film is irradiated with an energy ray to lower the adhesive force, and then peeled off from the optical member or the electronic member.

The attachment and peeling of the surface protective film is usually carried out by hand. At this time, by using the surface protective film of the present invention, it is attached to the light. When the surface of the member or the electronic member is learned, the deviation of the attachment position is less likely to occur, so that the number of times of reattachment can be reduced. Further, even when the surface protective film that has been attached is peeled off from the adherend, it can be peeled off without applying an excessive load, so that damage to the optical member or the electronic member as the adhering body can be prevented ( Cause deformation, damage, etc.).

The member with the surface protective film can be heated in the above steps of processing, mounting, inspection, or transportation. The heating temperature at this time is not particularly limited and may be 60 to 200 ° C, preferably 70 to 150 ° C. The adhesive layer sometimes has an increased adhesion due to heating. When the energy ray-curable adhesive composition is used as the adhesive layer of the surface protective film of the present invention, even if the adhesive force is increased by heating, the energy ray can be irradiated afterwards to lower the adhesive force, so when the surface protective film is peeled off It is not easy to cause poor peeling or residual glue.

An optical member or an electronic member (a member to which a surface protective film is attached) to which a surface protective film is attached is preferably attached to another member such as a substrate by an adhesive. In this case, in the case where the adhesive is thermosetting, the member having the surface protective film is usually heated at 60 to 200 ° C or higher, preferably 70 to 150 ° C, in order to cure the adhesive. Then, when the surface protective film is irradiated with an energy ray to reduce the adhesive force without performing surface protection, the surface protective film is peeled off from the optical member or the electronic member.

Further, as the surface protective film, in the above optical member or electronic member, a surface protective film for use as a photographic module is particularly preferably used.

a photography module, usually on the one side, provided with light from the outside Photosensitive is applied, and the light is introduced into the photosensitive portion inside the module through a lens inside the module. The photosensitive 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. The surface protective film is preferably attached to one surface of the photosensitive portion provided with the photographic module so as to cover the photosensitive portion. The surface protective film is adhered to the surface of the frame or the package around the photosensitive portion and the photosensitive portion with a high adhesion force before the irradiation of the energy ray, so that the photosensitive portion provided on one surface of the photographic module can be appropriately protected. Further, since the surface protective film is removed by the energy ray, since the adhesive force is lowered, it can be easily peeled off from the photographic module, and the residual portion of the photosensitive portion or the like can be prevented from being generated.

As described above, the photographic module to which the surface protective film is attached is preferably a member for heating the thermosetting adhesive and fixing it to a substrate or the like.

[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.

[test methods] <weight average molecular weight (Mw) of raw materials>

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

<Bending resistance of support>

The MD direction and the TD direction of the support were measured by the method according to JIS L 1913. However, the support was cut into a test piece of 20 mm × 150 mm using a 45° cantilever tester. Further, two test pieces were prepared for each of the test pieces used in the MD direction and the TD direction. Here, the test piece in the MD direction indicates that the longitudinal direction of the test piece is the MD direction of the support.

Each of the test pieces was subjected to measurement twice per time (both ends) on the surface and twice (both ends) on the back side, and the total bending length (mN‧ cm) was measured four times. The average value was calculated from the measurement results of the four times. The measurement was also performed in the same manner with respect to the TD direction.

From the measured value of the bending length of the two pieces of the test piece in the MD direction and the mass per unit area (g/m ² ) of the test piece used for the measurement, the MD bending resistance was calculated using the calculation formula described in JIS L 1913. Sex. Regarding the TD direction, the bending length measurement value of the two pieces of the test piece was also used to calculate the TD bending resistance.

The average value of the calculated value of the MD bending resistance and the TD bending resistance was obtained, and the bending resistance (mN‧ cm) of the support was obtained.

<Measurement of the depth of penetration (Z) of the buffer layer>

A microscopic dynamic hardness tester (manufactured by Shimadzu Corporation, product name "DUH-W201S"), and a triangular pyramid shape indenter with a radius of curvature of 100 nm at the front end of the indenter and an angle of 115° between the edges, at 23 ° C, 50 The measurement was carried out under the environment of % RH (relative humidity).

Specifically, the buffer layer of the surface protective film to be formed is exposed on the glass plate of the micro-dynamic hardness tester, and the front end of the triangular pyramid-shaped indenter is pressed at a speed of 10 μm /min. In the buffer layer, the indentation depth (Z) at which the compression load reached 2 mN was measured.

[Method for evaluating surface protective film] <through machining accuracy>

The through-edge is introduced into the surface protective film from the support side to perform the through process. The through-size system is set to a circle having a diameter of 5 mm. The surface protection film after the through process was measured for the X direction and the diameter in the Y direction orthogonal to the X direction, and evaluated by the following criteria.

A: The diameter in the X direction and the Y direction is within 5 ± 0.1 mm.

B: The diameter in the X direction and the Y direction exceeds 5 ± 0.1 mm

<Workability>

The surface protective film was processed into a circular shape having a diameter of 5 mm. Using tweezers The surface protective film is peeled off from the release sheet and bonded to a photographing module as a contact. Further, after UV irradiation, the surface protective film was peeled off from the photographic module using tweezers, and the workability was evaluated by the following criteria.

A: It is easy to peel off from the release sheet, and it is easy to adhere to the photographic module without any error. In addition, peeling after UV irradiation is also easy.

B: It takes time to peel off from the release sheet, and it takes time to bond to the photographing module, but peeling after UV irradiation is easy.

C: It is easy to peel off from the release sheet, and it is easy to adhere to the photographic module without any error, but peeling after UV irradiation is time consuming.

[Manufacturing Example 1] (Synthesis of urethane acrylate oligomer (UA-1))

The 2-hydroxyethyl acrylate is reacted with a terminal isocyanate urethane prepolymer obtained by reacting a polyester diol with isophorone diisocyanate to obtain a bifunctional amine group having a weight average molecular weight (Mw) of 5,000. Formate acrylic oligomer (UA-1).

[Example 1] (1) Modulation of a buffer layer forming composition

40 parts by mass of the urethane acrylate oligomer (UA-1) synthesized in Production Example 1 and an acrylic acid were mixed as the energy ray-polymerizable compound in a total amount of 100 parts by mass (solid content ratio). 40 parts by mass of oxime ester (IBXA), and phenylhydroxypropyl acrylate (HPPA) 20 parts by mass, and further added 0.1 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Corporation, product name "Irgacure 184") and 0.2 parts by mass of phthalocyanine-based pigment as a photopolymerization initiator, and modulation buffer A composition for layer formation.

(2) Production of support

The buffer layer-forming composition was applied to polyethylene terephthalate having a thickness of 50 μm so that the thickness after hardening became 20 μm (trade name; Cosmo Shine, model; A-4100) A substrate composed of Toyobo Co., Ltd.) was formed to form a coating film. The coating film is irradiated with ultraviolet rays, and the coating film is cured to form a buffer layer forming film.

For the irradiation of the ultraviolet rays, a conveyor belt type ultraviolet irradiation device (ECS-401GX, manufactured by Eye Graphics Co., Ltd.) and a high pressure mercury lamp (H04-L41, manufactured by Eye Graphics Co., Ltd.: H04-L41) were used, and the lamp height was 150 mm. The irradiation was carried out under the irradiation conditions of 3 kW (converted output 120 mW/cm), illuminance at a wavelength of 365 nm, 120 mW/cm ² , and an irradiation amount of 100 mJ/cm ² .

Then, the formed buffer layer was formed into a film surface and a release sheet (manufactured by Lintec Co., Ltd., trade name "SP-PET381031", polyethylene terephthalate (PET) film after polyoxynitridation treatment) The surface after the peeling treatment of the thickness: 38 μm ) was irradiated again with ultraviolet rays from the side of the release sheet on the buffer layer forming film, and the buffer layer forming film was completely cured to form a buffer layer having a thickness of 20 μm .

The irradiation of the ultraviolet rays is performed by using the ultraviolet irradiation device and the high-pressure mercury lamp at a lamp height of 150 mm, a lamp output of 3 kW (converted output of 120 mW/cm), a light beam of 365 nm of illuminance of 160 mW/cm ² , and an irradiation amount of 500 mJ/cm ² . Under the conditions.

(3) Formation of adhesive layer

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 120 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 the surface of the support on the substrate side so as to have a thickness of 20 μm after drying, and then dried by heating at 100 ° C for 1 minute to form an adhesive layer on the substrate. Surface protection film.

[Embodiment 2]

A surface protective film was produced in the same manner as in Example 1 except that the thickness of the buffer layer was changed to 50 μm .

[Example 3]

Use: a low-density polyethylene film (buffer layer) having a thickness of 25 μm was bonded to a substrate having the same thickness as 75 μm by an epoxy resin-based adhesive to obtain a support having a thickness of 75 μm . A surface protective film was produced in the same manner as in Example 1 except that it was the same as in Example 1.

[Example 4]

Production: a low-density polyethylene film (buffer layer and resin layer) having a thickness of 25 μm was bonded to both sides of the same substrate as in Example 1 by an epoxy resin-based adhesive to have a thickness of 100 μm . Support body. On the resin layer, an adhesive layer having a thickness of 20 μm as in Example 1 was formed to prepare a surface protective film.

[Example 5]

The substrate was produced in the same manner as in Example 1 except that polyethylene terephthalate (trade name; Cosmo Shine, model; A-4100, manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm was used. Surface protection film.

[Comparative Example 1]

A surface protective film was produced in the same manner as in Example 1 except that the buffer layer was not formed.

[Comparative Example 2]

A surface protective film was produced in the same manner as in Example 1 except that a low-density polyethylene film having a thickness of 80 μm was used.

[Comparative Example 3]

A surface protective film was produced in the same manner as in Example 1 except that a low-density polyethylene film having a thickness of 50 μm was used and the thickness of the buffer layer was changed to 50 μm .

[Comparative Example 4]

The substrate was produced in the same manner as in Example 1 except that polyethylene terephthalate (trade name; Cosmo Shine, model; A-4100, manufactured by Toyobo Co., Ltd.) having a thickness of 125 μm was used. Surface protection film.

From the first table, the surface protective films produced in Examples 1 to 5 were excellent in workability and workability.

On the other hand, in the surface protection film produced in Comparative Example 1, since the support has excellent bending resistance, workability is excellent, but since the buffer layer is not provided, the penetration depth to the substrate is shallow, resulting in poor workability. The result.

In Comparative Examples 2 and 3, since the support had low bending resistance, workability was poor, and in Comparative Example 4, the bending resistance of the support was too high, resulting in poor workability.

[Industrial Applicability]

The surface protection film of the present invention is excellent in workability and workability.

Therefore, as the surface protective film of the present invention, for example, a surface protective film which is a surface for protecting an optical member or an electronic member can be preferably used, and when used for the purpose, the film processability can be improved, and the adhesion to the member can be improved. The frequency of the re-sticking is increased and the damage to the adherend at the time of peeling is effectively prevented.

Claims (12)

A surface protective film for use in a surface protective film attached to an optical member or an electronic member to protect a surface thereof, the film having a support having a bending resistance of 5000 mN ‧ cm or more and 45000 mN ‧ cm or less; One side of the support body is provided with an adhesive layer, and the support system has a buffer layer composed of one or more selected from the group consisting of a buffer layer forming composition containing an energy ray polymerizable compound and a resin film for forming a buffer layer. The tip end of the triangular pyramid-shaped indenter having a radius of curvature of 100 nm and an inter-edge angle of 115° at a speed of 10 μm/min, and a compression depth (Z) required for the compression load when the buffer layer is pressed into 2 mN is 2.5 μm or more. The surface protective film of claim 1, wherein the support further has a substrate. The surface protective film according to claim 2, wherein the support is a support having a resin layer on a surface of the substrate opposite to a surface on which the buffer layer is provided. The surface protection film according to any one of claims 1 to 3, wherein the buffer layer is exposed on a side opposite to the adhesive layer. The surface protection film according to any one of claims 2 to 4, wherein the substrate is a resin film composed of polyethylene terephthalate. The surface protection film according to any one of claims 1 to 5, wherein the buffer layer-forming composition contains a urethane (meth) acrylate (a1) having a ring-forming atomic number of 6 to 20 An alicyclic or heterocyclic group polymerizable compound (a2), and a polymerizable compound having a functional group (a3), as the energy ray polymerizable compound. The surface protection film according to any one of claims 1 to 6, wherein the resin film for forming a buffer layer is a polyethylene film. The surface protection film according to any one of claims 1 to 7, wherein the buffer layer has a thickness of 5 to 100 μm. The surface protection film according to any one of claims 1 to 8, wherein the adhesive layer is composed of an energy ray-curable adhesive composition. The surface protection film according to any one of claims 1 to 9, wherein the adhesive layer is composed of an energy ray-curable adhesive composition containing an acrylic copolymer, and the acrylic copolymer contains at least 5 ~50% by mass of the alkyl group has a carbon number of 1 or 2 (meth)acrylic acid ester, and does not contain or contain less than 5% by mass of a monomer component of a carboxyl group-containing monomer. A member provided with a surface protective film, comprising an optical member or an electronic member, and a surface protective film according to any one of claims 1 to 10 attached to the surface of the optical member or the electronic member. A method of protecting a surface of an optical member or an electronic member to which a surface protective film according to any one of claims 1 to 10 is attached.