TWI697538B - Surface protection film - Google Patents

Abstract

The surface protection film of the present invention is a surface protection film that is adhered to an optical component or an electronic component to protect its surface. It has a substrate with a Young's modulus of 2500 MPa or less and a thickness of 50 μm or more, and a substrate provided on the substrate An adhesive layer with a storage elasticity of 0.1MPa or more on one side.

Description

Surface protection film

The present invention relates to a surface protective film laminated with an adhesive on one surface of a substrate, and particularly relates to a surface protective film adhered to the surface of various optical components or electronic components for protecting the surface.

Conventionally, when assembling electronic equipment, various electrical components and optical components are previously unitized and mounted on a substrate. As such unitized optical components and electronic components, most of them are known including image pickup components, lens units of cameras, communication components, sensor components, vibrators, and other motor units. In order to prevent surface damage during processing, assembling, inspection, and transportation of these optical components and electronic components, surface protection films are pasted.

The surface protection film is one where an adhesive layer is arranged on one surface of the substrate, and the surface of the adhered object is protected by the adhesive layer adhered to the adherend of the optical component or electronic component, and when the surface protection is not required, Those who are stripped from the adherend. In the past, surface protection films for optical or electronic components are known to use polyethylene terephthalate and polyethylene naphthalate esters as the base material, and the adhesive layer uses acrylic Acrylic acid-based adhesives or silicone-based adhesives (for example, refer to Patent Document 1).

[Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Publication No. 2005-341520

However, with the progress of miniaturization of the above-mentioned optical components or electronic components year by year, the size of the surface protection film accompanying this has also become smaller. For such a small-sized surface protection film, it is difficult to automatically mechanize the pasting and peeling operations, and the current situation is performed by hand.

However, if the small size surface protection film is pasted and peeled by hand, it will produce defects that do not occur in the normal label size. For example, even if the substrate and adhesive that are widely used for adhesive sheets are used, they will be peeled off. There are also cases of paste residue. If the paste remains in a miniaturized optical component or electronic component, even a small amount may cause quality degradation or malfunction.

Therefore, in order to prevent paste residue, it is also considered to reduce the adhesive force. However, when the adhesive force is simply reduced, the small-sized surface protection film is likely to peel off from the adherend inadvertently, and it is difficult to ensure sufficient protection performance. Moreover, if the substrate is thin, although it is not easy to produce the above-mentioned paste residue, but on a small surface When the protective film and the base material are significantly thinner, the handleability decreases.

The present invention was made in view of the above-mentioned problems. The object of the present invention is to provide a surface protection film that ensures proper adhesion and good handling properties even if the size of the surface protection film is small, and does not cause paste residue to be peeled off.

After investigating the mechanism of the occurrence of the paste residue, the inventors found that the lower half of the general substrate is mostly strong. Therefore, when the small-size surface protection film is peeled off by hand, the substrate is partially pressed into the adherend when it is peeled off. . Therefore, it is explored that in a surface protection film with a small size and a thick base material that requires a large flexural force during peeling, the pressing force becomes relatively large. Therefore, due to the pressing force, the adhesive scratches the adherend at the end of peeling. Paste residue occurred.

Therefore, the inventors of the present invention have actively reviewed the results and found that if the storage elasticity of the adhesive is high and the Young's modulus of the substrate is low, there is almost no such scratching, which prevents the paste from remaining and also makes the adhesive The force becomes an appropriate value and the adhesive performance is also good, and the following invention is completed. That is, the present invention provides the following (1) to (17).

(1) A surface protection film, which is a surface protection film pasted on optical or electronic components to protect the surface, characterized by having a substrate with a Young's modulus of 2900 MPa or less and a thickness of 50 μm or more, and An adhesive layer on one side of the substrate with a storage elastic modulus of 0.1 MPa or more.

(2) The surface protection film described in (1) above, wherein the film area is 20 cm ² or less.

(3) The surface protection film according to (1) or (2) above, wherein the thickness of the substrate is 300 μm or less.

(4) The surface protection film according to any one of (1) to (3) above, wherein the storage elastic modulus of the adhesive layer is 1 MPa or less.

(5) The surface protection film according to any one of (1) to (4) above, wherein the Young's modulus of the substrate is 500 MPa or more.

(6) The surface protection film described in any one of (1) to (5) above, wherein the adhesive force is 0.1 to 1.0 N/25mm.

(7) The surface protection film described in any one of (1) to (6) above, wherein the thickness of the adhesive layer is 3 to 45 μm.

(8) The surface protection film according to any one of (1) to (7) above, wherein the substrate is a laminate containing at least a polyethylene terephthalate film and a polyolefin film.

(9) The surface protection film described in any one of (1) to (8) above, wherein the adhesive layer is formed of an acrylic adhesive composition containing an acrylic polymer.

(10) The surface protection film described in (9) above, wherein the acrylic polymer contains at least 1 to 20% by mass of alkyl (meth)acrylate having an alkyl group of 1 or 2 carbon atoms, and an alkyl group A copolymer of monomers with a carbon number of 3-8 alkyl (meth)acrylate and 60-92% by mass.

(11) The surface protection film described in (9) or (10) above, wherein the acrylic polymer contains at least 0.1 to 2.5% by mass of a carboxyl group-containing monomer and 0.5 to 15% by weight of hydroxyl group-containing (meth)acrylate. quality % Monomer copolymer.

(12) The surface protection film described in any one of (9) to (11) above, wherein the acrylic adhesive composition contains 3 to 20 parts by mass of a crosslinking agent relative to 100 parts by mass of the acrylic polymer .

(13) The surface protection film according to any one of (1) to (12) above, wherein the adhesive layer is formed of a non-energy ray curable adhesive composition.

(14) The surface protection film described in any one of (1) to (13) above, which is adhered to the photographic component to protect the light-receiving part of the photographic component.

(15) The surface protection film described in any one of (1) to (14) above, wherein the Young's modulus of the substrate is 1000 to 2000 MPa, the thickness is 60 to 150 μm, and the storage elasticity of the adhesive layer The rate is 0.15~0.35MPa, the thickness is 5~45μm, and the adhesion is 0.1~0.6N/25mm.

(16) A member with a surface protection film, characterized by comprising a member selected from the group consisting of an optical member and an electronic member, and any one of the above (1) to (15) attached to the surface of the member Surface protection film.

(17) A method for protecting the surface of an optical component or an electronic component, characterized by attaching the surface protection film described in any one of (1) to (15) above to the surface of the optical component or electronic component to protect the surface.

According to the present invention, it is possible to provide The small size also ensures proper adhesion and good handling, and peels off the surface protective film without paste residue.

In the following description, the "weight average molecular weight" is a value measured in terms of polystyrene measured by a gel permeation chromatography (GPC) method, and specifically is a value measured based on the method described in the examples.

In addition, in the description in this specification, for example, "(meth)acrylate" is used as a term representing both "acrylate" and "methacrylate", and other similar functions are also the same.

Hereinafter, the present invention will be explained in more detail using embodiments.

The surface protection film of the present invention is adhered to an adherend selected from optical components or electronic components to protect the surface of the user. It has a substrate with a Young's modulus of 2900MPa or less and a thickness of 50μm or more, and a set An adhesive layer with a storage elastic modulus of 0.1 MPa or more on one side of the substrate. The surface protection film is adhered to the adherend through the adhesive layer for the user.

The surface protection film of the present invention is a relatively small-sized one used to protect relatively small optical components or electronic components. Furthermore, the base material of the surface protection film is relatively thick because it has good handling properties. That is, the surface protection film of the present invention has a small size and a thicker base material that is less likely to produce paste residue. By setting the Young's modulus of the base material and the storage elasticity of the adhesive layer to a certain value, The adhesion is good, and the paste residue is not easy to occur when the surface protective film is peeled from the adherend.

In the present invention, the Young's modulus of the base material is preferably 2900 MPa or less, and 500 MPa or more, as described above. If the Young's modulus of the substrate is greater than 2900MPa, the substrate will be pressed into the adherend with strong force when peeling off the surface protection film, and paste residue is likely to occur. And if the Young's modulus is greater than 2900 MPa, the adhesion of the surface protection film described later tends to decrease. On the other hand, by making the Young's modulus of the base material 500 MPa or more, a certain degree of rigidity can be imparted to the base material, and the surface protection film has a good surface rationality. Moreover, it is easy to adjust the adhesive force described later to a desired range.

The Young's modulus of the substrate, in order to ensure proper handling and adhesion, and to prevent paste residue, is preferably 600~2800MPa, and more preferably 1000~2000MPa.

In addition, the Young's modulus of the substrate is a value measured in accordance with JISK-7127 (1999).

In addition, if the thickness of the substrate is 50 μm or more as described above, if it is less than 50 μm, the handling properties will deteriorate, and it will be difficult to stick the surface protective film to the adherend and peel off by hand. In addition, in the press processing described later, it may be difficult to cut only the surface protection film without cutting the release sheet. On the other hand, the upper limit of the thickness of the substrate is not particularly limited, but from the viewpoint of good handleability, it is preferably 300 μm or less.

Based on the above viewpoints, the thickness of the substrate is more preferably 55 to 200 μm, and more preferably 60 to 150 μm.

In addition, the storage elastic modulus of the adhesive layer of the present invention is set to 0.1 MPa or more as described above. When the storage elastic modulus is less than 0.1MPa, the adhesive layer is too soft. When the Young's modulus of the substrate is as low as above, the adhesive force If it becomes higher, the peeling performance of the surface protection film decreases. Furthermore, paste residue is likely to occur. The storage elastic modulus of the adhesive layer is preferably 1 MPa or less. By setting it to 1 MPa or less, the adhesive layer is easy to exhibit good adhesiveness, and it is easy to properly protect the adherend.

The storage elasticity of the adhesive layer is preferably 0.12 to 0.5 MPa, more preferably 0.15 to 0.35 MPa in order to prevent the paste residue and make the adhesiveness good.

In addition, the storage elasticity can be adjusted by changing the material of the adhesive. For example, as described later, the storage elastic modulus can be improved by increasing the amount of crosslinking by containing a reactive functional group in the main polymer. Moreover, the storage elasticity can be reduced when the crosslinking dosage is reduced. Furthermore, it can also be adjusted by suitably changing the monomer type which comprises the main polymer, such as an acrylic polymer, or the weight average molecular weight of a main polymer.

In addition, the storage elastic modulus of the adhesive layer is the storage elastic modulus G'measured by the shear cutting method under an environment of 1 Hz and 23°C as described later.

If the adhesive layer is thinner, the adhesive force decreases, if it is thicker, the adhesive force increases. The thickness of the adhesive layer is usually adjusted to about 20-50μm. In addition, the thickness of the adhesive layer is preferably 3 to 45 μm, more preferably 5 to 25 μm in order to easily adjust the adhesive force to a desired range described later.

In addition, it can be used if the adhesive force of the surface protection film is about 1.5N/25mm or less, but it is preferably 0.1 to 1.0N/25mm. By setting the adhesive force of the protective surface film to 0.1N/25mm or more, after being adhered to the adherend, it can prevent inadvertent peeling from the adherend and can properly protect the adherend. And, by setting it to 1.5N/25mm or less, the protective surface film can be peeled off from the adherend by human hands, and then by setting it to 1.0N/25mm or less The protective surface film can be easily peeled off by hand. In addition, the adhesive force can be appropriately adjusted by appropriately changing the material constituting the adhesive as described later, or by changing the thickness of the adhesive or the Young's modulus of the substrate as described above.

The adhesive force of the protective surface film is preferably 0.2~0.9N/25mm, more preferably 0.25~0.6N/25mm in order to fully improve the balance of either the protective performance and the peelability.

In addition, the so-called adhesive force of the protective surface film means the adhesive force measured when the protective surface film is attached to a specific adherend and then peeled off as shown in the following examples.

In addition, the surface protection film of the present invention has a small size as described above, and the film area is usually set to 20 cm ² or less. By setting it as 20 cm ² or less, it can be suitably used as a surface protection film for miniaturized electronic components or optical components. On the other hand, the lower limit of the film area is not particularly limited, but from the viewpoint of practicality, it is preferably 0.05 cm ² or more.

In addition, the area of the film is more preferably 0.1 to 10 cm ² , and still more preferably 0.2 to 4 cm ^{2 in} order to easily exert the effects of the present invention and improve practicality.

In addition, in the present invention, the area of the film means the area of the substrate, for example, when a part of the substrate has unevenness, it is the area seen by the substrate in a plan view.

The shape of the surface protection film is not particularly limited. For example, it can be processed into a circle, a square, a rectangle, and the like. Moreover, the surface protection film is usually one with an adhesive layer provided on the entire substrate, but there may also be parts where the adhesive layer is not provided. For example, there may be a non-adhesive area where the adhesive layer is not provided in the central part of the surface direction of the substrate. And the substrate is usually flat, but it may also have a partially bulged shape. For example, only the central part of the substrate bulges and surrounds the central part Become a plane.

As above, when the non-adhesive area or the bulging part is provided in the center of the surface protection film, the center of the surface protection film does not contact the adherend. Therefore, even when a part of the adherend is composed of a precision member that causes defects if it comes into contact with the adhesive layer, the surface protection film of the present invention can be used.

In addition, in order to improve the visibility of the surface protection film, the base material or the adhesive layer can also be colored with pigments or dyes.

In addition, in the present invention, in order to achieve a good balance of paste residual characteristics, protective performance, proper handling, and peelability, the Young's modulus of the base material is preferably 500-2900MPa, the thickness is 50-300μm, and the storage elasticity of the adhesive layer The rate is 0.1~1MPa, the thickness is 3~45μm or less, and the adhesion of the surface protection film is 0.1~1.0N/25mm.

In addition, in order to achieve a better balance of the residual characteristics of the paste, handling suitability and peelability, it is better that the Young's modulus of the substrate is 1000~2000MPa, the thickness is 60~150μm, and the storage elasticity of the adhesive layer is 0.15~ 0.35MPa, thickness of 5~45μm and adhesion of surface protection film is 0.1~0.6N/25mm.

Next, the materials constituting the base material and the adhesive layer will be described in detail.

<Substrate>

As long as the base material has a Young's modulus within a specific range as described above, it may be composed of a single-layer resin film, or may be composed of multiple layers of resin films. However, in order to have an appropriate Young's modulus and good handling properties, multiple layers may be used. constitute.

When the substrate is a single-layer film, select the resin film system with a relatively low Young's modulus among general films. A specific example is low-density polyethylene (LDPE, density: 0.910g/cm ³ or more and less than 0.930g/ cm ³ ), medium density polyethylene (density: 0.930g/cm ³ or more and less than 0.942g/cm ³ ), high-density polyethylene (HDPE, density: 0.942g/cm ³ or more), etc. Polyolefin film such as ethylene film or polypropylene, polybutylene terephthalate, urethane acrylate cured film, non-stretch polypropylene film, etc.

In addition, when the substrate is composed of a plurality of layers, it is a laminate comprising a resin film with a relatively high Young's modulus and a resin film with a relatively low Young's modulus. Specifically, it is preferably used as a single-layer film. Each of the above-mentioned resin films and a laminate of a resin film having a Young's modulus higher than the resin film. Here, as a resin film with a high Young's modulus, for example, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfate film, polystyrene film, polycarbonate Ester film, biaxially stretched polypropylene film, etc. are preferably polyethylene terephthalate.

In order for the Young's modulus to have an appropriate value and good handling properties, the substrate is more preferably a laminate comprising ethylene terephthalate and polyolefin film, and more preferably comprises ethylene terephthalate and Laminated body of low density polyethylene film.

In addition, when the resin film is composed of multiple layers, it may be a two-layer structure of a resin film with a relatively high Young's modulus and a resin film with a relatively low Young's modulus, but it is preferably relative to the Young's modulus of the two layers. Between the low resin films, a three-layer structure with a relatively high Young's modulus resin film is provided. As a 3-layer structure A preferred example is a case where a low density polyethylene film, a polyethylene terephthalate film and a low density polyethylene film are arranged in sequence.

In addition, the substrate may be subjected to suitable surface treatment or the like to form a film or the like on the surface of the resin film. For example, it is also possible to form an easy bonding layer on the surface of the substrate where the adhesive layer is provided to improve the adhesion with the adhesive layer. The easy-adhesive layer system is formed of, for example, a polyester resin, a urethane resin, a polyester urethane resin, an acrylic resin, or the like.

In addition, the thickness of the base material means the total thickness of the base material. For example, when it is composed of a plurality of resin films, the total thickness of all resin films is the thickness of the substrate, and the thickness of the film layer having an easy-to-bond layer or the like is also included.

<Adhesive layer>

The adhesive that forms the adhesive layer is not particularly limited, and examples include acrylic adhesives, urethane adhesives, silicone adhesives, rubber adhesives, and polyester adhesives. These adhesives can be used 1 or in combination of 2 or more types. The adhesive is usually formed of an adhesive composition containing main polymer components such as acrylic resin (ie, acrylic polymer), urethane resin, polysiloxane resin, rubber component, and polyester resin. Among these adhesives, in order to make it easy to have an adhesive force of 0.1 to 1 N/25 mm and a storage elasticity of 0.1 MPa or more, an acrylic adhesive is preferred.

The following is a more detailed description of the use of acrylic adhesives as adhesives.

Acrylic adhesive (hereinafter also referred to as "acrylic adhesive composition "Things") are those containing acrylic polymer as the main polymer for imparting adhesiveness, and the acrylic polymer is the main component in the acrylic adhesive composition. That is, the acrylic polymer usually contains 50% by mass or more of the total amount of the composition, preferably 70% by mass or more, and more preferably 80% by mass or more.

Acrylic polymers are those that polymerize monomers containing at least alkyl (meth)acrylates. The alkyl (meth)acrylate is exemplified by those having a carbon number of 1 to 18, such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, ( N-propyl meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, (meth) ) Nonyl acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, etc.

Alkyl (meth)acrylate is usually contained at 50% by mass or more, preferably 60 to 99% by mass, more preferably 60 to 99% by mass relative to the total amount of monomers constituting the acrylic polymer (hereinafter also simply referred to as "the total amount of monomers") It is 70~97% by mass.

In the acrylic polymer, as the monomer component constituting the polymer, it is preferable that the alkyl (meth)acrylate has 1 or 2 carbon atoms in the alkyl (meth)acrylate relative to the total amount of the monomer The alkyl (meth)acrylate containing 1-20% by mass and the carbon number of the alkyl group is 3-8 is 60-92% by mass relative to the total amount of the monomer. Using a specific alkyl (meth)acrylate in such a ratio, it is easy to make the storage elastic modulus as mentioned above 0.1~1MPa or more, and it is easy to adjust the adhesive force to 0.1~1N/25mm.

Furthermore, as the monomer component in the acrylic polymer, the alkyl (meth)acrylate having a carbon number of 1 or 2 preferably contains 3 to 15% by mass relative to the total amount of the monomer, and the alkyl The alkyl (meth)acrylate having a carbon number of 3 to 8 contains 75 to 90% by mass.

In addition, in order to adjust the glass transition temperature of the adhesive so that the adhesiveness of the acrylic polymer is good, the above-mentioned alkyl (meth)acrylate-based alkyl methacrylate having a carbon number of 1 or 2 is preferred. On the other hand, the alkyl (meth)acrylate having 3-8 carbon atoms in the alkyl group is preferably alkyl acrylate in order to exhibit excellent adhesion, and the carbon tree of the alkyl group is preferably 4-6.

In addition, alkyl (meth)acrylates having 1 or 2 carbon atoms in the alkyl group are exemplified by methyl (meth)acrylate and ethyl (meth)acrylate. Among these, methyl (meth)acrylate is preferred. ester.

In addition, the alkyl (meth)acrylate having 3 to 8 carbon atoms in the alkyl group is preferably n-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, etc., more preferably acrylic acid N-butyl ester.

The acrylic polymer is preferably one obtained by copolymerizing a monomer further containing a polymerizable monomer other than the aforementioned alkyl (meth)acrylate, and such a monomer is preferably a monomer having a functional group. The functional group-containing single system provides, for example, the necessary functional group for reacting with the crosslinking agent described later, and adjusts the adhesive force. The functional group-containing monomer is a monomer having a polymerizable double bond and functional groups such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, and an epoxy group in the molecule. Among these, a hydroxyl group and a carboxyl group are preferred.

The above-mentioned functional group-containing monomers preferably contain carboxyl group-containing monomers in order to improve the adhesion of the surface protective film. Relative to carboxyl-containing monomers The total amount of the monomer is preferably from 0.1 to 2.5% by mass, more preferably from 0.5 to 2.0% by mass. In this way, by using a small amount of carboxyl group-containing monomers, the storage elasticity can be adjusted to an appropriate value, and the adhesive force can be appropriately improved. Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, and itaconic acid, and acrylic acid is preferred.

In addition, the functional group-containing monomer preferably further contains a hydroxyl group-containing compound, and more preferably contains a hydroxyl group-containing (meth)acrylate. The hydroxyl group-containing (meth)acrylate is preferably 0.5 to 15% by mass relative to the total amount of the monomer. By setting the content of the hydroxyl group-containing (meth)acrylate in the above range, the acrylic polymer can be appropriately crosslinked by the crosslinking agent described below, and the storage elastic modulus or adhesive force can be easily adjusted to an appropriate value. In addition, the content of the hydroxyl-containing (meth)acrylate is more preferably 2-10% by mass.

Specific examples of hydroxyl-containing (meth)acrylates are 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, (meth) 2-hydroxybutyl acrylate and the like.

These hydroxyl-containing (meth)acrylates can be used alone or in combination of two or more kinds.

Acrylic polymers may be (meth)acrylates, dialkyl (meth)acrylic acid esters other than the above monomers, alkyl (meth)acrylates and functional group-containing monomers Amine, vinyl formate, vinyl acetate, styrene, vinyl acetate and other monomers copolymerized. As (meth)acrylates other than alkyl (meth)acrylates and functional group-containing monomers, alkoxyalkyl (meth)acrylates, alkoxyalkyl (meth)acrylates, (Meth) nonylphenoxy polyethylene glycol acrylate, tetrahydrofurfuryl acrylate, polyether and acrylic acid ester Acrylics.

In addition, as the dialkyl (meth)acrylamide, dimethyl (meth)acrylamide, diethyl (meth)acrylamide, and the like are used.

The weight average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 100,000 to 1,500,000, and still more preferably 200,000 to 1,200,000. By making the range of the weight average molecular weight within the above range, it is easy to adjust the storage elastic modulus and adhesive force of the adhesive layer to a desired range.

The acrylic adhesive composition preferably contains a crosslinking agent. By using a crosslinking agent, the acrylic polymer has a crosslinking structure in the adhesive layer. Examples of the crosslinking agent include isocyanate-based crosslinking agents, reducing oxygen-based crosslinking agents, aziridine-based crosslinking agents, metal chelate-based crosslinking agents, etc. Among these, isocyanate-based crosslinking agents are preferred, It is also preferable to use an isocyanate-based crosslinking agent in combination with other crosslinking agents.

The isocyanate-based crosslinking agent is exemplified by organic polyvalent isocyanate compounds, specifically, aromatic polyvalent isocyanate compounds, aliphatic polyvalent isocyanate compounds, alicyclic polyvalent isocyanate compounds, and the third of these organic polyvalent isocyanate compounds Polymers, and terminal isocyanate urethane prepolymers obtained by reacting these organic polyvalent isocyanate compounds with polyol compounds.

Further specific examples of the isocyanate crosslinking agent are 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, and diphenylmethane-4 ,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, two Cyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate; these urets; trimethylolmethane such as adducts of toluene diisocyanate and trimethylolpropane Modification of toluene diisocyanate, trimethylolpropane such as adduct of xylene diisocyanate and trimethylolpropane, etc. Among these, toluene diisocyanate modified by trimethylolpropane and xylene diisocyanate modified by trimethylolpropane are preferred.

Specific examples of epoxy-based crosslinking agents are, for example, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl -M-xylene diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine, etc. .

Specific examples of aziridine-based crosslinking agents are diphenylmethane-4,4'-bis(1-aziridine carboxyamide), trimethylolpropane tris-β-aziridinyl propionate , Tetra-hydroxymethylmethane tris-β-aziridinyl propionate, toluene-2,4-bis(1-aziridine carboxyamide), trimethylene melamine, bis-m-xylylenedimethanyl -1-(2-methylaziridine), ginseng-1-(2-methylaziridine)phosphine, trimethylolpropane tris-β-(2-methylaziridinyl)propionate Wait.

The metal chelate-based crosslinking agent includes metal-based chelate compounds such as aluminum, zirconium, titanium, zinc, iron, and tin, but from the viewpoint of performance, aluminum chelate compounds are preferred. Examples of aluminum chelate compounds include aluminum diisopropoxide monooleyl acetate, monoisopropoxide aluminum dioleyl acetate, monoisopropoxide aluminum monooleate Monoethyl acetyl acetate, diisopropoxy aluminum monolauryl acetyl acetate, diisopropoxy aluminum monostearyl acetyl acetate, diisopropoxy aluminum monoisohard Tallow Acetate, Monoisopropoxy Aluminum mono-N-lauryl-β-aluminum hydride monolauryl acetate, triacetyl aluminum acetate, monoacetyl acetate aluminum bis (isobutyl acetyl acetate) chelate Monoacetate aluminum bis(2-ethylhexylacetate) chelate, monoacetate aluminum bis(dodecylacetate) chelate, single Aluminum acetyl acetate bis(oleyl acetyl acetate) chelate and the like, of which ginseng aluminum acetate is preferred.

The content of the crosslinking agent in the acrylic adhesive composition is preferably 3 to 20 parts by mass relative to 100 parts by mass of the acrylic polymer. If the content of the crosslinking agent is more than the above lower limit, the acrylic polymer can be appropriately crosslinked, and the storage elastic modulus can be easily adjusted to 0.1 MPa or more. Moreover, by being below the upper limit value, excessive crosslinking can be prevented, the storage elastic modulus can be prevented from becoming too high, and the adhesive force can be prevented from decreasing.

In addition, in order to make the storage elastic modulus and the adhesive force easily reach the above-mentioned preferable values, the content of the crosslinking agent is more preferably 4 to 15 parts by mass, and more preferably 5 to 9 parts by mass.

The acrylic adhesive composition may easily contain additives other than the crosslinking agent within the range that does not impair the effect of the present invention. Examples of such additives include antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, etc., energy ray polymerizable compounds, photopolymerization initiators, and the like.

In addition, the adhesive composition constituting the adhesive layer is preferably a non-energy ray-curable adhesive composition. The so-called non-energy-ray-curable adhesive composition means that, like the energy-ray-curable adhesive composition described later, the composition does not contain components that are hardened by energy rays. Even if energy rays are irradiated, The adhesive force of the adhesive layer formed by the composition has not changed. In the present invention, energy ray curability is not imparted to the adhesive layer, and by adjusting the Young's modulus of the substrate and the storage elasticity of the adhesive layer as mentioned above, the peeling performance of the surface protective film can be improved. And can prevent paste residue. In addition, specific examples of energy rays include ultraviolet rays, electron beams, and the like.

However, the adhesive composition may also be an energy ray hardening type adhesive composition. The energy ray curable adhesive composition is not particularly limited if it has energy ray curability, and an X-type is used as a preferred aspect.

The X-type energy ray curable adhesive composition is the main polymer (for example, acrylic polymer) of the adhesive having energy ray curability. For example, in the case of an acrylic adhesive composition, it becomes an energy ray curable acrylic polymer in which at least a part of the above-mentioned acrylic polymer has an unsaturated group in the side chain.

However, the adhesive curable adhesive composition may also be a Y-type energy ray curable adhesive composition. The Y-type energy-ray curable adhesive composition is prepared by blending an energy-ray polymerizable compound with the main polymer (for example, acrylic polymer) for exerting adhesiveness to impart energy-ray curability. As the energy-ray polymerizable compound, epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate, and other energy-ray polymerizable oligomers or energy-ray polymerizable compounds are used monomer. These energy ray polymerizable compounds have at least two or more photopolymerizable carbon-carbon double bonds in the molecule. Furthermore, X-type and Y-type can also be used together as an energy-beam curable adhesive composition. That is, the energy-ray curable adhesive composition may contain energy-ray polymerizable properties in addition to the main polymer. And at least a part of the main polymer has an unsaturated group in the side chain.

In addition, when the adhesive layer is formed of an energy-ray curable adhesive composition, after being adhered to the adherend, it can be cured by irradiating energy rays before peeling off the adherend. In this case, the adherend can be appropriately protected with high adhesive force during pasting, and the adhesive force becomes low when peeling from the adherend, so it is easy to prevent the paste from remaining. At this time, the above-mentioned adhesive force means the adhesive force before the energy ray is irradiated, and the peelability is good even if the adhesive force is high, so its upper limit can be higher than 1.5N/25mm.

In addition, when the adhesive layer is formed of an energy-ray curable adhesive composition, the surface protection film can also be irradiated with energy rays before being adhered to the adherend.

In the adhesive layer of the surface protection film, in order to protect the adhesive layer, a release sheet can also be attached. As a peeling sheet, it can be used for peeling on one side of a resin film such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene, etc. with a release agent such as silicone resin Processors, etc., but not limited to them. In addition, the surface protection film may be provided in plural on one release sheet of a size sufficiently larger than the surface protection film.

The method of forming the adhesive layer is not particularly limited. The adhesive composition diluted with an appropriate solvent can be applied to the release sheet as needed, and then heated and dried to form the adhesive layer, and then the base is pasted on the adhesive layer The material can be formed.

Moreover, the adhesive composition diluted with an appropriate solvent as needed can also be directly coated on the substrate, and then heated and dried to form an adhesive layer. The adhesive layer formed in this way is also better to adhere the release sheet.

As manufactured above, it has a substrate, adhesive layer and peeling thin The laminated body of the sheet (also referred to as the "adhesive sheet") is preferably cut from the base material in such a way as to surround a specific part (surface protection film part), and then subjected to punching processing. Here, the cut marks are formed by cutting into the base material and the adhesive layer, but not cutting into the release sheet. After the punching process, the laminate of the adhesive layer and the substrate except the surface protection film part is removed from the release sheet to form a surface protection film with a specific shape on the release sheet.

[Optical component or electronic component]

As an optical component or electronic component protected by the surface protection film of the present invention, for example, one or more lenses and a camera sensor such as CCD, CMOS, etc. are housed in a housing or a photographic component inside a package; plural lens holding A lens unit in the lens barrel and housed in a frame or package as needed; a light-emitting element unit with light-emitting elements such as LEDs; a motor unit such as a vibrator; communication components and sensor components. These optical components or electronic components are preferably used for mounting on other components such as a substrate.

In addition, the term "optical member" refers to an optical member that receives light, emits light, or transmits light, such as the above-mentioned camera module, lens unit, light-emitting element unit, communication module that transmits or receives optical signals, and light sensor module. As a specific example of an optical member. Moreover, the so-called electronic components are usually exemplified as at least a part of a circuit, electronic components that transmit or receive electrical signals, electronic components that process electrical signals, electronic components that are actuated by electrical signals or electricity, etc., such as the aforementioned camera components , Light-emitting element units, motor units such as vibrators, communication components that transmit or receive electrical signals, and various sensor components are specific examples of electronic components. Again, send Or communication components or light sensor components, camera components, and light-emitting element units that receive optical signals are usually electronic components and also optical components.

In addition, the optical member or the electronic member is preferably, for example, one that houses the above-mentioned electronic member or optical member in a package or a housing or is supported by a supporting member. Moreover, it is preferable that a part of an electronic component or an optical component is exposed on the surface, and a surface protection film is used, for example to protect the exposed component.

[How to use surface protective film]

The surface protection film of the present invention is adhered to the surface of the adherend selected from the optical component or the electronic component to protect the surface of the user. Specifically, the optical component or electronic component to which the surface protection film is attached (hereinafter also referred to as the "component with surface protection film") is processed, installed on other components, inspected or transported, etc. The surface protection film is Protect the surface of optical components or electronic components in these steps. In addition, the surface protection film is peeled off from the optical member or the electronic member when the steps are completed and surface protection is not required.

In addition, the surface of the adherend on which the surface protection film is adhered may be flat, or may have steps or unevenness. If there are steps or irregularities, paste residue is likely to occur in the steps or irregularities. However, the surface protective film of the present invention can prevent paste residue even in this case.

The adhesion of the surface protection film to the adherend and the peeling from the adherend are usually performed by hand. These operations can be performed by directly grasping the surface protection film with fingers, or by using a tool such as a pin holder.

In addition, the member with a surface protection film can also be heated in the steps of processing, installation, inspection, or transportation described above. The heating temperature at this time is not particularly limited, but is about 60 to 200°C, preferably about 70 to 150°C. Moreover, heating is performed in order to harden the thermosetting adhesive used for mounting an optical member or an electronic member (a member with a surface protection film) to another member.

In addition, the surface protection film is particularly preferably used as a surface protection film for imaging devices among the above-mentioned optical components or electronic components.

The imaging component is usually provided with a light-receiving part, which is used to receive light from the outside on one side and guide the light through the lens inside the component to the imaging element. The light-receiving part is arranged on a part (for example, the center) of one surface of the imaging component, and is made of glass or transparent resin. The surface protection film is better to be pasted to cover the light-receiving part on one side of the imaging component where the light-receiving part is provided.

[Example]

Hereinafter, the present invention will be described in further detail based on examples, but the present invention is not limited by these examples.

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

[Weight average molecular weight (Mw)]

The gel permeation chromatography (GPC) was used to measure under the following conditions, and the value measured in terms of standard polystyrene was used.

(Measurement conditions)

Measuring device: Product name "HLC-8220GPC", manufactured by TOSOH Co., Ltd.

Column: Product name, "TSKGel SuperHZM-M", manufactured by TOSOH Co., Ltd.

Developing solvent: tetrahydrofuran

Column temperature: 40℃

Flow rate: 1.0mL/min

[Measurement of Young's Modulus of Substrate]

The Young's modulus of the substrate was measured according to JISK-7127 (1999) at a test speed of 200mm/min.

[Measurement of storage elasticity of adhesive]

Using a viscoelasticity measuring device (manufactured by ANTON PAAR, device name "MCR300"), a sample of an adhesive layer with a diameter of 8 mm × a thickness of 1 mm was measured by the shearing and cutting method under an environment of 1 Hz and 23°C. G'. In addition, in the following Examples and Comparative Examples, the above samples are obtained by laminating an adhesive layer formed from a solution of the adhesive composition under the same conditions as the Comparative Example.

[Thickness of base material and adhesive layer]

According to JIS K7130, a constant pressure thickness measuring device (manufactured by TECLOCK, product name "PG-02") is used for measurement. In addition, the thickness of the adhesive layer is measured by measuring the thickness of the adhesive sheet, and subtracting the thickness of the substrate and the release sheet from this value. Got the value.

[Adhesion]

The adhesive force is measured in accordance with JISZ 0237 with a width of 25 mm. However, the adherend is LPC VECTRA A130 (trade name, manufactured by POLYPLASTICS Co., Ltd.), and the adhesive sheet (surface protective film) cut into a width of 25mm is reciprocated once with a 2kg roller and adhered to the adherend by pressure on. Adhesive force is measured after being placed in an environment of 23°C and 50% relative humidity for 24 hours, using a Tensilon universal tensile testing machine to measure the adhesive force when peeling at a peeling angle of 180°.

In addition, in the following examples and comparative examples, since the surface protection film has a small size, the sample cannot be collected, so the adhesive sheet before press processing is cut as the sample.

[Evaluation of paste residue]

After the surface protection film is adhered to the soda lime glass, it is placed in a dry environment at 85°C (relative humidity 0%) for 4 hours, and then placed at 23°C and 50% relative humidity for 24 hours, then the surface protection film is peeled off. The paste residue on the glass was observed with a wide-field confocal microscope "HD100D" (manufactured by LASER LOCK Co., Ltd.), and the state was evaluated based on the following criteria.

A: No paste residue

B: Part of the paste remains but no problem

C: There are many paste residues and there are problems in actual use

[Evaluation of handling suitability] <Paste Workability>

The surface protection film obtained by pressing into a size of 7 mm (38.5 mm ² ) in diameter was peeled off from the release film using a pin holder, and the workability when pasting to an optical member was evaluated by the following criteria.

A: The film is not slack, and the workability is good

B: Some tasks are difficult but can be pasted

C: The film has large slack and poor workability

[Example 1]

Using 86 parts by mass of n-butyl acrylate, 8 parts by mass of methyl methacrylate, 1 part by mass of acrylic acid and 5 parts by mass of 2-hydroxyethyl acrylate as raw material monomers, solution polymerization was carried out in an ethyl acetate solution to obtain acrylic Solution of polymer (weight average molecular weight: 800,000).

In this acrylic polymer solution, the solid content ratio is 7.5 parts by mass relative to 100 parts by mass of the acrylic polymer (solid content), and an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd.) , Trade name "CORONATE L"), to obtain a solution of adhesive composition (1).

The adhesive composition (1) was applied to a PET film (manufactured by LINTEC Co., Ltd., trade name "SP-PET751031") that was subjected to a silicone peeling treatment on a peeling sheet so that the thickness after drying became 20μm. After noodles, dry at 100°C for 1 minute to form an adhesive layer.

Next, prepare a low density polyethylene film (density: 0.923g/m ³ , thickness 27.5μm)/polyethylene terephthalate film (thickness 25.0μm)/low density polyethylene film (density: 0.923g/ A resin film with a total thickness of 80 μm formed by three layers of m ³ , 27.5 μm in thickness) is used as the substrate A, and the substrate A is stuck on the adhesive layer to obtain an adhesive sheet. Subsequently, press processing was performed to obtain a circular surface protection film (film area: 0.38 cm ² ) with a diameter of 7 mm. The evaluation results of the surface protection film are shown in Table 1.

[Example 2]

The amount of the isocyanate-based crosslinking agent added to the adhesive composition (1) was changed to a solid content ratio of 4 parts by mass to obtain an adhesive composition (1)'. Using this adhesive composition (1)' and substrate A, an adhesive tape was obtained in the same manner as in Example 1. Subsequently, press processing was performed, and in the same manner as in Example 1, a circular surface protection film with a diameter of 7 mm was obtained.

[Example 3]

Except that the base material pasted on the adhesive layer was changed to base material C made of a non-stretched polypropylene film (manufactured by Toyobo Co., Ltd., trade name "PYLEN FILM CT P1147" with a thickness of 80 μm), it was the same as Example 1 Obtain adhesive tape. Subsequently, press processing was performed, and in the same manner as in Example 1, a circular surface protection film with a diameter of 7 mm was obtained.

[Example 4]

In addition to changing the base material pasted on the adhesive layer to a low-density polyethylene film (density: 0.923g/m ³ , thickness 27.5μm)/polyethylene terephthalate film (thickness 50.0μm)/low An adhesive tape was obtained in the same manner as in Example 1, except for a resin film substrate D with a total thickness of 105 μm composed of three layers of a density polyethylene film (density: 0.923 g/m ³ , thickness 27.5 μm). Subsequently, press processing was performed, and in the same manner as in Example 1, a circular surface protection film with a diameter of 7 mm was obtained.

[Example 5]

Using 75.5 parts by mass of n-butyl acrylate, 18.9 parts by mass of 2-ethylhexyl acrylate, and 5.6 parts by mass of 4-hydroxybutyl acrylate as raw material monomers, solution polymerization was performed in an ethyl acetate solution to obtain an acrylic polymer ( Weight average molecular weight: 700,000) solution. In this acrylic polymer solution, an isocyanate-based crosslinking agent (manufactured by Asahi Kasei Chemical Co., Ltd., trade name ", with a solid content ratio of 3.75 parts by mass relative to 100 parts by mass of the acrylic polymer (solid content) DURANATE 24A-100") and an aluminum chelate crosslinking agent (manufactured by Soken Chemical Co., Ltd., trade name "M" with a solid content ratio of 0.25 parts by mass relative to 100 parts by mass of acrylic polymer (solid content) -2A”) to obtain a solution of adhesive composition (3).

The adhesive composition (3) was adhered to the substrate A in the same manner as in Example 1 to obtain an adhesive tape. Subsequently, press processing was performed, and in the same manner as in Example 1, a circular surface protection film with a diameter of 7 mm was obtained.

[Example 6]

The same procedure as in Example 2 was carried out except that the thickness of the adhesive layer was 50 μm.

[Example 7]

The same procedure as in Example 1 was carried out except that the thickness of the adhesive layer was 2 μm.

[Example 8]

Except that the thickness of the adhesive layer was set to 5 μm, it was carried out in the same manner as in Example 2.

[Example 9]

Except that the thickness of the adhesive layer was set to 10 μm, it was carried out in the same manner as in Example 1.

[Example 10]

Except that the thickness of the adhesive layer was 25 μm, it was carried out in the same manner as in Example 1.

[Example 11]

Except that the thickness of the adhesive layer was set to 45 μm, it was carried out in the same manner as in Example 5.

[Comparative Example 1]

Combine 68.6 parts by mass of 2-ethylhexyl acrylate, 30 parts by mass of methyl acrylate, 0.2 parts by mass of glycidyl methacrylate, 1.2 parts by mass of acrylic acid, and 1 part by mass of glycidylpropyltrimethoxysilane in ethyl acetate. Solution polymerization was performed in the solution to obtain a solution of acrylic polymer (weight average molecular weight: 800,000).

In this acrylic polymer solution, an aziridine-based crosslinking agent (manufactured by TOYOKEM Co., Ltd., trade name) having a solid content ratio of 0.5 parts by mass relative to 100 parts by mass of the acrylic polymer (solid content) "BXX5172") to obtain a solution of adhesive composition (2). The adhesive composition (2) was applied to the release film in the same manner as in Example 1 to form an adhesive layer, and the adhesive layer was adhered to the adhesive layer made of polyethylene terephthalate (Toyobo Co., Ltd.) An adhesive sheet is obtained on the easy-adhesive layer side surface of the substrate B made by the company, trade name "COSOMOSHINE A4300", thickness: 100μm). Subsequently, press processing was performed, and in the same manner as in Example 1, a circular surface protection film with a diameter of 7 mm was obtained.

[Comparative Example 2]

Except the point that the base material stuck to the adhesive layer was changed to base material B, it carried out similarly to Example 1, and obtained the adhesive sheet. Subsequently, press processing was performed, and in the same manner as in Example 1, a circular surface protection film with a diameter of 7 mm was obtained.

[Comparative Example 3]

Except that the base material stuck to the adhesive layer was changed to base material A, the same procedure was performed as in Comparative Example 1 to obtain an adhesive sheet. Subsequently, press processing was performed, and in the same manner as in Example 1, a circular surface protection film with a diameter of 7 mm was obtained.

As understood from Table 1 above, the surface protection films of Examples 1 to 11 are those with a small size and a larger substrate thickness. However, since the Young’s modulus of the substrate and the storage elasticity of the adhesive are set to specific values, When the adherend was peeled off, no paste residue occurred, and even if it did, there was very little paste residue. In addition, because the adhesive force of Example 6 is higher than 1.0N/25mm, the peeling performance is lower than that of other examples. Furthermore, the adhesive force of Example 7 is lower than 0.1N/25mm, and the protection performance is less than that of other examples.

On the other hand, in Comparative Examples 1 to 3, since at least any one of the Young's modulus of the base material or the storage elastic modulus of the adhesive layer is outside the specified range, the paste remains or the adhesive is too high and the peeling performance difference.

Claims (16)

A surface protective film pasted on a photographic component to protect the light-receiving part of the photographic component. It is a surface protective film pasted on an optical component or an electronic component to protect its surface. It is characterized by having a Young's modulus of 2900MPa Below, a substrate with a thickness of 50 μm or more, and an adhesive layer provided on one surface of the substrate with a storage elasticity of 0.1 MPa or more, the thickness of the adhesive layer is 5-25 μm. The surface protection film according to claim 1, wherein the film area is 20 cm ² or less. The surface protection film according to claim 1 or 2, wherein the thickness of the base material is 300 μm or less. The surface protection film according to claim 1 or 2, wherein the storage elastic modulus of the adhesive layer is 1 MPa or less. The surface protection film according to claim 1 or 2, wherein the Young's modulus of the substrate is 500 MPa or more. Such as the surface protection film described in claim 1 or 2, wherein the adhesive force is 0.1~1.0N/25mm. The surface protection film according to claim 1 or 2, wherein the thickness of the adhesive layer is 3 to 45 μm. The surface protective film according to claim 1 or 2, wherein the substrate is a laminate containing at least a polyethylene terephthalate film and a polyolefin film. The surface protection film according to claim 1 or 2, wherein the adhesive layer is composed of an acrylic adhesive group containing an acrylic polymer Formed into things. The surface protective film according to claim 9, wherein the acrylic polymer contains at least 1 to 20% by mass of an alkyl (meth)acrylate having an alkyl carbon number of 1 or 2 and an alkyl carbon number of 3. ~8 Alkyl (meth)acrylate copolymer with 60~92% by mass monomer. The surface protective film according to claim 9, wherein the acrylic polymer is a copolymer of at least 0.1 to 2.5% by mass of a carboxyl group-containing monomer and 0.5 to 15% by mass of a hydroxyl group-containing (meth)acrylate monomer Things. The surface protection film according to claim 9, wherein the acrylic adhesive composition contains 3 to 20 parts by mass of the crosslinking agent relative to 100 parts by mass of the acrylic polymer. The surface protection film according to claim 1 or 2, wherein the adhesive layer is formed of a non-energy ray curable adhesive composition. The surface protection film as described in claim 1 or 2, wherein the Young's modulus of the aforementioned base material is 1000~2000MPa, the thickness is 60~150μm, the storage elasticity of the aforementioned adhesive layer is 0.15~0.35MPa, and the thickness is 5 ~45μm, and the adhesion is 0.1~0.6N/25mm. A member with a surface protection film, characterized by comprising a member selected from any one of an optical member and an electronic member, and a surface protection film described in any one of claims 1 to 14 pasted on the surface of the member. A method for protecting the surface of an optical component or an electronic component, which is characterized in that the surface protection film described in any one of claims 1 to 14 is adhered to the surface of the optical component or the electronic component to protect the surface.