JP6895250B2 - Surface protective film - Google Patents

Description

The present invention relates to an optical surface protective film with a separator. In particular, the adhesive constituting the optical surface protective film used for protecting the surface of an optical member (for example, a polarizing plate used for a liquid crystal display, a wave plate, a retardation plate, an optical compensation film, a reflective sheet, a brightness improving film, etc.) By attaching (laminating) a specific separator used to protect the surface of the agent layer until actual use, it is excellent in peelability and workability, and further, it is possible to prevent the occurrence of dents, which is useful.

The surface protective film generally has a structure in which an adhesive layer is provided on a film-like base film (support). Such a surface protective film is attached to an optical member which is an adherend via the adhesive layer, and is used for the purpose of protecting the optical member from scratches and stains on the surface during processing, transportation, inspection, and the like. Be done. For example, a panel of a liquid crystal display is formed by bonding optical members such as a polarizing plate and a wave plate to a liquid crystal cell via an adhesive layer. The pressure-sensitive adhesive layer is protected and stored by a release-treated separator or the like from the need to protect it from drying or the like until it is actually attached to the optical member (Patent Document 1).

After that, when the surface of the pressure-sensitive adhesive layer of the surface protective film is actually attached to the optical member and used, the separator is peeled off and removed.

JP 2012-224811

When the separator is thick, it is peeled off, and when the separator has a high peeling force (adhesive force) against the pressure-sensitive adhesive layer constituting the surface protective film of the separator, a problem of inferior peelability and workability occurs.

Further, when a thin separator is used instead of the thick separator when the adhesive is applied, it is caused by fine particles (for example, polyester-based filler) contained in the base material or the like constituting the separator adhering to the surface of the separator. Therefore, when the pressure-sensitive adhesive layer is formed, it causes dents on the surface of the pressure-sensitive adhesive layer. Further, when the adhesive layer is attached to the adherend with dents on the surface, air bubbles enter the dented portion (space) between the adhesive layer and the adherend, and the adherend is inspected. There arises a problem of deteriorating the inspectability in.

Therefore, as a result of diligent research in view of the above circumstances, the present inventors have specified the thickness of the polyester-based base material constituting the separator to be laminated on the optical surface protective film, and further provided a cavity to make the separator stiff. By weakening (rigidity), the peeling force of the separator against the pressure-sensitive adhesive layer can be suppressed, and the peelability and workability are excellent. Furthermore, by having a cavity, the cushioning property is excellent, and the dents caused by the separator It is an object of the present invention to provide an optical surface protective film with a separator which can suppress the occurrence and has excellent inspectability.

That is, the optical surface protective film with a separator of the present invention is an optical surface protective film having an adhesive layer on at least one side of the base film, and a surface of the pressure-sensitive adhesive layer opposite to the surface in contact with the base film. In addition, an optical surface protective film with a separator having a separator, wherein the separator has a release layer and a polyester-based base material, the polyester-based base material has a cavity, and the polyester-based base material has a cavity. The thickness is 25 to 100 μm, and the 180 ° trigger peeling force of the separator with respect to the pressure-sensitive adhesive layer is 0.7 N / 50 mm or less.

The optical surface protective film with a separator of the present invention preferably has a cavity ratio of 15% or more with respect to the volume of the polyester-based base material.

In the optical surface protective film with a separator of the present invention, it is preferable that the base film is a polyester film.

In the optical surface protective film with a separator of the present invention, it is preferable that the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing a (meth) acrylic polymer.

In the present invention, the thickness of the polyester-based base material constituting the separator to be laminated on the optical surface protective film is specified, and by further providing a cavity, the peeling force of the separator against the pressure-sensitive adhesive layer constituting the optical surface protective film can be obtained. It suppresses, has excellent peelability and workability, and has a cavity, so that the separator with excellent cushioning property can suppress the occurrence of dents due to the separator, and an optical surface protective film can be applied to the adherend. It is useful because an optical surface protective film with a separator having excellent inspectability can be obtained in a bonded state.

It is a schematic cross-sectional view which shows one structural example of the optical surface protection film with a separator which concerns on this invention. It is a schematic cross-sectional view which shows one structural example when the separator is peeled off from the optical surface protection film with a separator which concerns on this invention.

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

<Overall structure of optical surface protective film with separator>
The optical surface protective film with a separator disclosed herein (hereinafter, may be simply referred to as “surface protective film”) is generally referred to as an adhesive tape, an adhesive label, an adhesive film, or the like. Is protected by a separator, and in particular, surface protection that protects the surface of optical components (for example, optical components used as liquid crystal display panel components such as polarizing plates and wavelength plates) during processing, inspection, and transportation. Suitable as a film. The pressure-sensitive adhesive layer in the surface protective film is typically formed continuously, but is not limited to such a form, and is formed in a regular or random pattern such as a dot shape or a striped shape. It may be an adhesive layer. Further, the surface protective film disclosed herein may be in the form of a roll or in the form of a single leaf.

<Base film>
The optical surface protective film constituting the optical surface protective film with a separator of the present invention is characterized by having a base film. In the technique disclosed herein, the resin material constituting the base film can be used without particular limitation, and for example, transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property, and the like are possible. It is preferable to use one having excellent properties such as flexibility and dimensional stability. In particular, since the base film has flexibility, the pressure-sensitive adhesive composition can be applied by a roll coater or the like, and can be wound into a roll shape, which is useful.

As the base film (support), for example, polyester-based polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate; cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate-based polymers; The base material is a plastic film composed of a resin material containing an acrylic polymer such as polymethylmethacrylate; or the like as a main resin component (main component of the resin component, typically a component accounting for 50% by weight or more). It can be preferably used as a film. Other examples of the resin material include styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers; olefin-based polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers; Examples thereof include those using a vinyl chloride polymer; an amide polymer such as nylon 6, nylon 6, 6, and aromatic polyamide; and the like as a resin material. Still other examples of the resin material include imide-based polymers, sulfone-based polymers, polyether sulfone-based polymers, polyether ether ketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, and vinyl butyral-based polymers. , Arilate-based polymer, polyoxymethylene-based polymer, epoxy-based polymer and the like. It may be a base film composed of a blend of two or more of the above-mentioned polymers.

As the base film, a plastic film made of a transparent thermoplastic resin material can be preferably adopted. Among the plastic films, it is more preferable to use a polyester film. Here, the polyester film mainly contains a polyester polymer material (polyester resin) having a main skeleton based on an ester bond such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate. Say something. Such a polyester film has preferable properties as a base film for a surface protective film, such as excellent optical properties and dimensional stability.

If necessary, the resin material constituting the base film may contain various additives such as an antioxidant, an ultraviolet absorber, a plasticizer, and a colorant (pigment, dye, etc.). For example, known or conventional surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and undercoating may be applied. Such a surface treatment may be, for example, a treatment for enhancing the adhesion between the base film and the pressure-sensitive adhesive layer (the anchoring property of the pressure-sensitive adhesive layer).

As the base film, it is also possible to use a plastic film which has been subjected to antistatic treatment. It is preferable to use the base film because the charge of the surface protective film itself at the time of peeling can be suppressed. Further, the base film is a plastic film, and by subjecting the plastic film to an antistatic treatment, it is possible to reduce the charge on the surface protective film itself and obtain an excellent antistatic ability on the adherend. The method for imparting the antistatic function is not particularly limited, and a conventionally known method can be used. For example, an antistatic resin, a conductive polymer, or a conductive substance composed of an antistatic agent and a resin component can be used. Examples thereof include a method of applying the contained conductive resin, a method of depositing or plating a conductive substance, and a method of kneading an antistatic agent or the like.

The thickness of the base film is usually about 5 to 200 μm, preferably about 10 to 100 μm. When the thickness of the base film is within the above range, it is preferable because it is excellent in sticking workability to the adherend, peelability from the adherend, and workability.

The surface protective film disclosed herein may also be implemented in an embodiment that includes, in addition to the base film, the pressure-sensitive adhesive layer, and the separator, yet another layer. Examples of the other layer include an antistatic layer and an undercoat layer (anchor layer) that enhances the anchoring property of the pressure-sensitive adhesive layer.

<Adhesive layer>
The pressure-sensitive adhesive layer used in the present invention can be used without particular limitation as long as it is formed from a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive polymer having adhesiveness. As the pressure-sensitive adhesive composition, for example, an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a synthetic rubber-based pressure-sensitive adhesive, a natural rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, and the like can be used. , Acrylic adhesives, urethane adhesives, and silicone adhesives are preferably used (containing) at least one selected from the group, and the (meth) acrylic polymer which is the adhesive polymer is used. It is a particularly preferable embodiment to use the contained pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive).

When the pressure-sensitive adhesive layer uses an acrylic pressure-sensitive adhesive, the (meth) acrylic-based polymer, which is a pressure-sensitive adhesive polymer constituting the acrylic pressure-sensitive adhesive, is an alkyl having 1 to 14 carbon atoms as a raw material monomer constituting the pressure-sensitive adhesive polymer. A (meth) acrylic monomer having a group can be used as the main monomer. As the (meth) acrylic monomer, one kind or two or more kinds can be used. By using the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, it becomes easy to control the peeling force (adhesive force) to the adherend (protected body) to be low, and light peeling becomes possible. A surface protective film having excellent properties and removability can be obtained. The (meth) acrylic polymer in the present invention refers to an acrylic polymer and / or a methacrylic polymer, and the (meth) acrylate refers to an acrylate and / or methacrylate.

Specific examples of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl (meth). ) Acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl ( Examples include meta) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate. Be done.

Among them, in the surface protective film of the present invention, in particular, n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate , N-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) ) A (meth) acrylic monomer having an alkyl group having 4 to 14 carbon atoms such as acrylate is preferable. In particular, by using a (meth) acrylic monomer having an alkyl group having 4 to 14 carbon atoms, it becomes easy to control the peeling force (adhesive force) to the adherend to be low, and the material has excellent removability. It becomes.

In particular, it is preferable to contain 65% by weight or more of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms with respect to 100% by weight of the total amount of the monomer components constituting the (meth) acrylic polymer. , More preferably 75% by weight or more, further preferably 85 to 99.9% by weight, and most preferably 90 to 99% by weight. If it is less than 50% by weight, the appropriate wettability of the pressure-sensitive adhesive composition and the cohesive force of the pressure-sensitive adhesive layer will be inferior, which is not preferable.

Further, as the (meth) acrylic polymer, a hydroxyl group-containing (meth) acrylic monomer can be used as the raw material monomer. As the hydroxyl group-containing (meth) acrylic monomer, one kind or two or more kinds can be used. By using the hydroxyl group-containing (meth) acrylic monomer, it becomes easier to control cross-linking of the pressure-sensitive adhesive composition, and by extension, a balance between improvement of wettability due to flow and reduction of peeling force (adhesive force) in peeling is achieved. It becomes easier to control.

Examples of the hydroxyl group-containing (meth) acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. , 8-Hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, and the like. ..

The hydroxyl group-containing (meth) acrylic monomer is preferably contained in an amount of 25% by weight or less, more preferably 15% by weight or less, based on 100% by weight of the total amount of the monomer components constituting the (meth) acrylic polymer. More preferably, it is 0.1 to 10% by weight. When it is within the above range, it is easy to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the obtained pressure-sensitive adhesive layer, which is preferable.

In addition, as other polymerizable monomer components, the Tg is set to 0 ° C. or lower (usually -100 ° C. or higher) so that the adhesive performance can be easily balanced, and the glass transition temperature and peeling of the (meth) acrylic polymer are set. A polymerizable monomer for adjusting the property can be used as long as the effect of the present invention is not impaired.

Further, as the (meth) acrylic polymer, a carboxyl group-containing (meth) acrylic monomer can be used as the raw material monomer. By using the carboxyl group-containing (meth) acrylic monomer, it is possible to suppress an increase in the adhesive strength of the pressure-sensitive adhesive layer (surface protective film) over time, and it is possible to suppress the increase in the adhesive strength over time, and the removability, the adhesive strength increase prevention property, and the work. Excellent in sex. Further, it is preferable because it has excellent shearing force as well as cohesive force of the pressure-sensitive adhesive layer.

Examples of the carboxyl group-containing (meth) acrylic monomer include (meth) acrylic acid, carboxylethyl (meth) acrylate, and carboxylpentyl (meth) acrylate.

The amount of the carboxyl group-containing (meth) acrylic monomer is preferably 10% by weight or less, preferably 0 to 8% by weight, based on 100% by weight of the total amount of the monomer components constituting the (meth) acrylic polymer. Is more preferable, and 0 to 6% by weight is further preferable. When it is within the above range, it is easy to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the obtained pressure-sensitive adhesive layer, which is preferable.

Further, the (meth) acrylic polymer can be used without particular limitation as long as other polymerizable monomers other than the raw material monomer are not impaired in the characteristics of the present invention. For example, as the other polymerizable monomer, a cohesive force / heat resistance improving component such as a cyano group-containing monomer, a vinyl ester monomer, and an aromatic vinyl monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, and an epoxy A group-containing monomer, N-acryloylmorpholine, vinyl ether monomer, or other component having a functional group that acts as an improvement in peeling power (adhesive power) or a cross-linking base point can be appropriately used. Among them, it is preferable to use a cyano group-containing monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, and a nitrogen-containing monomer such as N-acryloylmorpholine. By using the nitrogen-containing monomer, it is possible to secure an appropriate peeling force (adhesive force) that does not cause floating or peeling, and it is possible to obtain a surface protective film having excellent shearing force, which is useful. As these polymerizable monomers, one kind or two or more kinds can be used.

Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, N, N-dimethylmethacrylicamide, N, N-diethylacrylamide, N, N-diethyl. Examples thereof include methacrylamide, N, N'-methylenebisacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylaminopropyl methacrylamide, diacetone acrylamide and the like.

Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and N, N-dimethylaminopropyl (meth) acrylate.

Examples of the vinyl ester monomer include vinyl acetate, vinyl propionate, vinyl laurate and the like.

Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes.

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

Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether and the like.

In the present invention, the other polymerizable monomer is preferably 0 to 30% by weight, preferably 0 to 10% by weight, based on 100% by weight of the total amount of the monomer components constituting the (meth) acrylic polymer. Is more preferable. The other polymerizable monomers can be appropriately adjusted to obtain the desired properties.

The (meth) acrylic polymer may further contain an alkylene oxide group-containing reactive monomer as a monomer component.

The average number of moles of the oxyalkylene unit added to the alkylene oxide group-containing reactive monomer is preferably 1 to 40 from the viewpoint of compatibility with the oxyalkylene group-containing compound, and is preferably 3 to 40. Is more preferable, 4 to 35 is further preferable, and 5 to 30 is particularly preferable. When the average number of added moles is 1 or more, the effect of reducing contamination of the adherend (protected body) tends to be efficiently obtained. Further, when the average number of moles added is larger than 40, the interaction with the oxyalkylene group-containing compound is large, and the viscosity of the pressure-sensitive adhesive composition tends to increase, which tends to make coating difficult, which is not preferable. The terminal of the oxyalkylene chain may remain as a hydroxyl group or may be substituted with another functional group or the like.

The alkylene oxide group-containing reactive monomer may be used alone or in combination of two or more, but the total content is the total amount of the monomer components of the (meth) acrylic polymer. Of the above, 0 to 20% by weight is preferable, and 0 to 10% by weight is more preferable. If the content of the alkylene oxide group-containing reactive monomer exceeds 20% by weight, the contamination of the adherend deteriorates, which is not preferable.

Examples of the oxyalkylene unit of the alkylene oxide group-containing reactive monomer include those having an alkylene group having 1 to 6 carbon atoms, and examples thereof include an oxymethylene group, an oxyethylene group, an oxypropylene group, and an oxybutylene group. Be done. The hydrocarbon group of the oxyalkylene chain may be linear or branched.

Further, it is more preferable that the alkylene oxide group-containing reactive monomer is a reactive monomer having an ethylene oxide group. By using a reactive monomer-containing (meth) acrylic polymer having an ethylene oxide group as the base polymer, the compatibility between the base polymer and the oxyalkylene group-containing compound is improved, and bleeding to the adherend is suitably suppressed. A low-contamination pressure-sensitive adhesive composition is obtained.

Examples of the alkylene oxide group-containing reactive monomer include a (meth) acrylate alkylene oxide adduct and a reactive surfactant having a reactive substituent such as an acryloyl group, a methacryloyl group, and an allyl group in the molecule. can give.

Specific examples of the (meth) acrylate alkylene oxide adduct include polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol (meth) acrylate, and polyethylene glycol-polybutylene glycol (meth). ) Acrylic, Polyethylene Glycol-Polybutylene Glycol (Meta) acrylate, methoxypolyethylene Glycol (Meta) acrylate, ethoxypolyethylene Glycol (Meta) acrylate, Butoxypolyethylene Glycol (Meta) acrylate, Octoxypolyethylene glycol (Meta) acrylate, Lauroxypolyethylene Glycol (meth) acrylate, stearoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol-polypropylene glycol (meth) acrylate and the like can be mentioned.

Specific examples of the reactive surfactant include, for example, an anionic reactive surfactant having a (meth) acryloyl group or an allyl group, a nonionic reactive surfactant, a cationic reactive surfactant, and the like. Can be given.

The (meth) acrylic polymer preferably has a weight average molecular weight (Mw) of 100,000 to 5 million, more preferably 200,000 to 4 million, still more preferably 300,000 to 3 million, and most preferably 300,000 to 1.2 million. Is. When the weight average molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive layer is reduced, which tends to cause adhesive residue. On the other hand, when the weight average molecular weight exceeds 5 million, the fluidity of the polymer decreases, the wettability to the adherend (for example, the polarizing plate) becomes insufficient, and the adherend and the pressure-sensitive adhesive layer of the surface protective film Tends to cause blisters that occur during. The weight average molecular weight is obtained by measuring by GPC (gel permeation chromatography).

The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 0 ° C. or lower, more preferably −10 ° C. or lower (usually −100 ° C. or higher). When the glass transition temperature is higher than 0 ° C., the polymer does not easily flow, for example, the polarizing plate, which is an optical member, is not sufficiently wetted, and the blisters generated between the polarizing plate and the pressure-sensitive adhesive layer of the surface protective film. Tends to be the cause. In particular, when the glass transition temperature is set to −70 ° C. or lower, it becomes easy to obtain an adhesive layer having excellent wettability to a polarizing plate and light peelability. The glass transition temperature of the (meth) acrylic polymer can be adjusted within the above range by appropriately changing the monomer component and composition ratio used.

The polymerization method of the (meth) acrylic polymer is not particularly limited, and can be polymerized by a known method such as solution polymerization, emulsion polymerization, massive polymerization, suspension polymerization, etc., but particularly from the viewpoint of workability and subject matter. Solution polymerization is a more preferable embodiment from the viewpoint of characteristics such as low contamination of the body (protected body). Further, the obtained polymer may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer and the like.

<Oxyalkylene group-containing compound>
The pressure-sensitive adhesive composition used in the present invention can also contain an oxyalkylene group-containing compound. By containing an oxyalkylene group-containing compound, it is possible to further develop light peelability. Examples of the oxyalkylene group-containing compound include an organopolysiloxane having an oxyalkylene chain and an oxyalkylene group-containing compound containing no organopolysiloxane.

Specific examples of the organopolysiloxane having an oxyalkylene chain include specific examples of an organopolysiloxane having an oxyalkylene chain in the main chain, for example, as a commercial product, the trade names are X-22-4952 and X-22. -4272, X-22-6266, KF-6004, KF-889 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), BY16-201, SF8427 (above, manufactured by Toray Dow Corning), IM22 (manufactured by Asahi Kasei Wacker), etc. Can be given. Examples of the organosiloxane having an oxyalkylene chain on the side chain include commercially available products with trade names KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, and KF-945. , KF-640, KF-642, KF-643, KF-6022, X-22-6191, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017, X-22-2516 (The above is manufactured by Shin-Etsu Chemical Co., Ltd.) SF8428, FZ-2162, SH3749, FZ-77, L-7001, FZ-2104, FZ-2110, L-7002, FZ-2122, FZ-2164, FZ-2203, FZ -7001, SH8400, SH8700, SF8410, SF8422 (all manufactured by Toray Dow Corning), TSF-4440, TSF-4441, TSF-4445, TSF-4450, TSF-4446, TSF-4452, TSF-4460 (momentive) Performance Materials), BYK-333, BYK-307, BYK-377, BYK-UV3500, BYK-UV3570 (manufactured by Big Chemie Japan) and the like. These compounds may be used alone or in combination of two or more.

Specific examples of the oxyalkylene group-containing compound containing no organopolysiloxane include polyoxyalkylene alkylamine, polyoxyalkylenediamine, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, and polyoxyalkylene alkylphenyl ether. , Polyoxyalkylene alkyl ether, polyoxyalkylene alkyl allyl ether, polyoxyalkylene alkyl phenyl allyl ether and other nonionic surfactants; polyoxyalkylene alkyl ether sulfate ester salt, polyoxyalkylene alkyl ether phosphoric acid ester salt, poly Anionic surfactants such as oxyalkylene alkyl phenyl ether sulfates and polyoxyalkylene alkyl phenyl ether phosphates; other cationic surfactants having polyoxyalkylene chains (polyalkylene oxide chains) and amphoteric Examples thereof include a surfactant, a polyether compound having a polyoxyalkylene chain (including a derivative thereof), an acrylic compound having a polyoxyalkylene chain (including a derivative thereof), and the like. Further, the polyoxyalkylene chain-containing monomer may be blended as a polyoxyalkylene chain-containing compound. Such a polyoxyalkylene chain-containing compound may be used alone or in combination of two or more.

Specific examples of the polyether compound (polyether component) having a polyoxyalkylene chain include a block copolymer of polypropylene glycol (PPG) -polyethylene glycol (PEG), a block copolymer of PPG-PEG-PPG, and the like. Examples thereof include block copolymers of PEG-PPG-PEG. Examples of the derivative of the polyether compound having a polyoxyalkylene chain include an oxypropylene group-containing compound having an etherified terminal (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.) and an oxypropylene having an acetylated terminal. Group-containing compounds (terminal acetylated PPG, etc.), and the like can be mentioned.

Further, specific examples of the acrylic compound having a polyoxyalkylene chain include a (meth) acrylate polymer having an oxyalkylene group. As the oxyalkylene group, the number of moles of the oxyalkylene unit added is preferably 1 to 50, more preferably 2 to 30, and even more preferably 2 to 20. Further, the terminal of the oxyalkylene chain may remain as a hydroxyl group or may be substituted with an alkyl group, a phenyl group or the like.

The (meth) acrylate polymer having an oxyalkylene group is preferably a polymer containing (meth) acrylate alkylene oxide as a monomer component, and specific examples of the (meth) acrylate alkylene oxide are ethylene. Examples of the glycol group-containing (meth) acrylate include methoxy-polyethylene glycol (meth) acrylate type such as methoxy-diethylene glycol (meth) acrylate and methoxy-triethylene glycol (meth) acrylate, ethoxy-diethylene glycol (meth) acrylate, and ethoxy. -Ethoxy-polyethylene glycol (meth) acrylate type such as triethylene glycol (meth) acrylate, butoxy-polyethylene glycol (meth) acrylate type such as butoxy-diethylene glycol (meth) acrylate, butoxy-polyethylene glycol (meth) acrylate type such as butoxy-triethylene glycol (meth) acrylate, phenoxy Phenoxy-polyethylene glycol (meth) acrylate type such as −diethylene glycol (meth) acrylate, phenoxy-triethylene glycol (meth) acrylate, 2-ethylhexyl-polyethylene glycol (meth) acrylate, nonylphenol-polyethylene glycol (meth) acrylate type, methoxy Examples thereof include methoxy-polypropylene glycol (meth) acrylate type such as -dipropylene glycol (meth) acrylate.

Further, as the monomer component, other monomer components other than the (meth) acrylic acid alkylene oxide can also be used. Specific examples of other monomer components include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, and isobutyl (meth) acrylate. , Hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate , Isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate and other acrylates having an alkyl group having 1 to 14 carbon atoms and / or methacrylate. Be done.

Further, as other monomer components other than the (meth) acrylate alkylene oxide, a carboxyl group-containing (meth) acrylate, a phosphoric acid group-containing (meth) acrylate, a cyano group-containing (meth) acrylate, vinyl esters, and an aromatic vinyl compound , Acid anhydride group-containing (meth) acrylate, hydroxyl group-containing (meth) acrylate, amide group-containing (meth) acrylate, amino group-containing (meth) acrylate, epoxy group-containing (meth) acrylate, N-acryloyl morpholine, vinyl ethers Etc. can be used as appropriate.

In a more preferred embodiment, the polyoxyalkylene chain-containing compound containing no organopolysiloxane is a compound having at least a part (poly) ethylene oxide chain. By blending the (poly) ethylene oxide chain-containing compound, the compatibility with the base polymer is improved, bleeding to the adherend is preferably suppressed, and a low-contamination pressure-sensitive adhesive composition can be obtained. Above all, when a block copolymer of PPG-PEG-PPG is used, a pressure-sensitive adhesive having excellent low contamination property can be obtained. As the polyethylene oxide chain-containing compound, the weight of the (poly) ethylene oxide chain in the entire polyoxyalkylene chain-containing compound containing no organopolysiloxane is preferably 5 to 90% by weight, more preferably 5 to 85%. By weight%, more preferably 5 to 80% by weight, most preferably 5 to 75% by weight.

Further, as commercially available products of the polyoxyalkylene chain-containing compound containing no organopolysiloxane, for example, ADEKA PLRONIC 17R-4, ADEKA PLLONIC 25R-2 (all manufactured by ADEKA), Latemul PD-420, Latemul PD. -420, Latemuru PD-450, Emargen 120 (manufactured by Kao), Aqualon HS-10, KH-10, Neugen EA-87, EA-137, EA-157, EA-167, EA-177 (above, No. 1) (Manufactured by Industrial Pharmaceutical Co., Ltd.) and the like.

The content of the oxyalkylene group-containing compound is 0.01 to 5 with respect to 100 parts by weight of the adhesive polymer (main polymer, for example, (meth) acrylic polymer) constituting the pressure-sensitive adhesive composition. It is preferably 0 parts by weight, more preferably 0.02 to 2 parts by weight, still more preferably 0.03 to 1.6 parts by weight, and most preferably 0.1 to 0.8 parts by weight. When it is within the above range, the pressure-sensitive adhesive layer (surface protective film) used in the present invention is likely to exhibit light peelability (removability), which is preferable.

<Crosslinking agent>
In the surface protective film of the present invention, it is preferable that the pressure-sensitive adhesive composition contains a cross-linking agent. Further, in the present invention, the pressure-sensitive adhesive composition can be used to form a pressure-sensitive adhesive layer. For example, when the pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive containing the (meth) acrylic polymer, the constituent units, the constituent ratios, the selection and addition ratio of the cross-linking agent, etc. of the (meth) acrylic polymer are appropriately selected. By adjusting and cross-linking, an adhesive layer (surface protective film) having more excellent heat resistance can be obtained.

As the cross-linking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative, a metal chelate compound and the like may be used, and the use of an isocyanate compound and an epoxy compound is particularly preferable. Further, these compounds may be used alone or in combination of two or more.

Examples of the isocyanate compound include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI) and dimerate diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), 1, Alicyclic isocyanates such as 3-bis (isocyanatomethyl) cyclohexane, aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate (XDI), and the isocyanate compounds. Examples thereof include polyisocyanate modified products modified by allophanate bond, biuret bond, isocyanurate bond, uretdione bond, urea bond, carbodiimide bond, uretonimine bond, oxadiazine trione bond and the like. For example, as commercially available products, the trade names are Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takeda D178N (all manufactured by Takeda Pharmaceutical Company Limited), Sumijour T80, Sumijour L, Death Module N3400 (above, Sumika Bayer Urethane). , Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (all manufactured by Nippon Polyurethane Industry Co., Ltd.) and the like. These isocyanate compounds may be used alone or in combination of two or more, or a bifunctional isocyanate compound and a trifunctional or higher isocyanate compound may be used in combination. By using a cross-linking agent in combination, it is possible to achieve both adhesiveness and resilience (adhesiveness to a curved surface), and it is possible to obtain an adhesive layer (surface protective film) having more excellent adhesive reliability.

Examples of the epoxy compound include N, N, N', N'-tetraglycidyl-m-xylene diamine (trade name: TETRAD-X, manufactured by Mitsubishi Gas Chemical Company, Inc.) and 1,3-bis (N, N-diamine). Glycidylaminomethyl) cyclohexane (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.) and the like can be mentioned.

Examples of the melamine-based resin include hexamethylol melamine. Examples of the aziridine derivative include commercially available commercial products such as HDU, TAZM, and TAZO (all manufactured by Mutual Pharmaceutical Co., Ltd.).

Examples of the metal chelate compound include aluminum, iron, tin, titanium and nickel as metal components, and acetylene, methyl acetoacetate and ethyl lactate as chelate components.

The content of the cross-linking agent used in the present invention is, for example, preferably 0.01 to 20 parts by weight, preferably 0.1 to 15 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer. More preferably, it is more preferably 0.5 to 10 parts by weight, and most preferably 1 to 8 parts by weight. If the content is less than 0.01 parts by weight, the cross-linking by the cross-linking agent may be insufficient, the cohesive force of the obtained pressure-sensitive adhesive layer may be small, and sufficient heat resistance may not be obtained. It tends to cause adhesive residue. On the other hand, when the content exceeds 20 parts by weight, the cohesive force of the polymer is large, the fluidity is lowered, the wettability to the adherend (for example, the polarizing plate) is insufficient, and the adherend and the pressure-sensitive adhesive are used. It tends to cause blisters that occur between the layer (adhesive composition layer). Further, these cross-linking agents may be used alone or in combination of two or more.

<Crosslink catalyst>
The pressure-sensitive adhesive composition may further contain a cross-linking catalyst for more effectively advancing any of the above-mentioned cross-linking reactions. Examples of such cross-linking catalysts include tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris (acetylacetonato) iron, tris (hexane-2,4-dionat) iron, and tris (heptane-2,4-dionat). ) Iron, Tris (Heptane-3,5-Zionato) Iron, Tris (5-Methylhexane-2,4-Zionato) Iron, Tris (Octane-2,4-Zionato) Iron, Tris (6-Methylheptane-2) , 4-Zionato) Iron, Tris (2,6-dimethylheptane-3,5-Zionato) Iron, Tris (Nonan-2,4-Zionato) Iron, Tris (Nonan-4,6-Zionato) Iron, Tris ( 2,2,6,6-tetramethylheptane-3,5-dionat) iron, tris (tridecane-6,8-dionat) iron, tris (1-phenylbutane-1,3-dionat) iron, tris (hexa) Fluoroacetylacetonato) iron, tris (ethylacetate acetate) iron, tris (acetoacetate-n-propyl) iron, tris (isopropylacetate isopropyl) iron, tris (acetoacetate-n-butyl) iron, tris (acetoacetate- sec-butyl) iron, tris (acetoacetate-tert-butyl) iron, tris (propionylmethylacetate) iron, tris (propionylacetate ethyl) iron, tris (propionylacetate-n-propyl) iron, tris (propionylacetate isopropyl) Iron, Tris (propionyl acetate-n-butyl) iron, Tris (propionyl acetate-sec-butyl) iron, Tris (propionyl acetate-tert-butyl) iron, Tris (benzyl acetoacetate) iron, Tris (dimethyl malonate) iron , Tris (diethyl malonate) iron, trimethoxy iron, triethoxy iron, triisopropoxy iron, ferric chloride and other iron-based catalysts can be used. These cross-linking catalysts may be used alone or in combination of two or more.

The content of the cross-linking catalyst is not particularly limited, but is preferably about 0.0001 to 1 part by weight, preferably 0.001 to 0.5 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer, for example. Parts by weight are more preferred. When it is within the above range, the rate of the cross-linking reaction is high when the pressure-sensitive adhesive layer is formed, and the pot life of the pressure-sensitive adhesive composition is long, which is a preferable embodiment.

Further, the pressure-sensitive adhesive composition may contain other known additives, for example, powders such as lubricants, colorants and pigments, plasticizers, pressure-sensitive adhesives, low-molecular-weight polymers and surface lubrication. Agents, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, UV absorbers, polymerization inhibitors, silane coupling agents, antistatic agents, inorganic or organic fillers, metal powders, particulates, foils It can be added as appropriate depending on the intended use of the substance.

<Optical surface protection film with separator>
The optical surface protective film (surface protective film) with a separator of the present invention is formed by forming the pressure-sensitive adhesive layer on at least one side of the base film, and at that time, the cross-linking of the pressure-sensitive adhesive composition is adhesive. It is generally performed after the application of the agent composition, but it is also possible to transfer the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition after cross-linking to a base film or the like.

The method of forming the pressure-sensitive adhesive layer on the base film is not particularly limited. For example, the pressure-sensitive adhesive composition (solution) is applied to the base film, and a polymerization solvent or the like is dried and removed to form the pressure-sensitive adhesive layer. It is produced by forming it on a base film. After that, curing may be performed for the purpose of adjusting the component transfer of the pressure-sensitive adhesive layer, adjusting the cross-linking reaction, and the like. Further, when the pressure-sensitive adhesive composition is applied onto the base film to prepare a surface protective film, one or more kinds other than the polymerization solvent may be contained in the pressure-sensitive adhesive composition so that the pressure-sensitive adhesive composition can be uniformly applied on the base film. A new solvent may be added.

Further, as a method for forming the pressure-sensitive adhesive layer when manufacturing the surface protective film of the present invention, a known method used for manufacturing pressure-sensitive adhesive tapes is used. Specific examples thereof include a roll coat, a gravure coat, a reverse coat, a roll brush, a spray coat, an air knife coat method, and an extrusion coat method using a die coater or the like.

The surface protective film of the present invention is usually prepared so that the thickness of the pressure-sensitive adhesive layer is about 3 to 100 μm, preferably about 5 to 50 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, it is easy to obtain an appropriate balance between removability and adhesiveness, which is preferable.

The total thickness of the surface protective film of the present invention is preferably 8 to 300 μm, more preferably 10 to 200 μm, and most preferably 20 to 100 μm. When it is within the above range, it is excellent in adhesive properties (removability, adhesiveness, etc.), workability, and appearance characteristics, and is a preferable embodiment. The total thickness means the total thickness including all layers such as the base film, the pressure-sensitive adhesive layer, the separator, and other layers.

<Separator>
The surface protective film of the present invention has an adhesive layer on at least one side of the base film, and has a separator on the surface of the pressure-sensitive adhesive layer opposite to the surface in contact with the base film. However, it has a release layer and a polyester-based base material, the polyester-based base material has a cavity, the thickness of the polyester-based base material is 25 to 100 μm, and 180 of the separator with respect to the pressure-sensitive adhesive layer. ° The trigger peeling force is 0.7 N / 50 mm or less. The separator is for sticking a separator to the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive surface of the pressure-sensitive adhesive layer. In particular, by having a specific thickness and a cavity, the stiffness (rigidity) of the separator itself can be improved. It can be kept low, has excellent peelability and workability when peeling the separator from the surface of the pressure-sensitive adhesive layer, and can provide cushioning properties due to cavities, and can prevent glue dents that may occur after coating the pressure-sensitive adhesive. It can be prevented and becomes a preferable embodiment.

<Polyester base material>
The polyester-based base material (sometimes simply referred to as "base material") is not particularly limited as long as it is a polyester-based film that can protect the pressure-sensitive adhesive layer and has cavities, and is, for example, polyethylene terephthalate film or polyethylene. Examples thereof include naphthalate film and polybutylene terephthalate film.

The thickness of the polyester-based substrate is 25 to 100 μm, preferably 30 to 80 μm, and more preferably 40 to 70 μm. When it is within the above range, it is preferable because it is excellent in sticking workability to the pressure-sensitive adhesive layer and peelability and workability to the pressure-sensitive adhesive layer. If the thickness of the base material exceeds 100 μm, the stiffness (rigidity) of the separator itself becomes strong, and the peelability and workability are inferior, which is not preferable.

The surface of the polyester-based base material can be subjected to various surface treatments such as corona discharge treatment and various surface treatments such as embossing, if necessary. In addition, if necessary, fillers (inorganic fillers, organic fillers, etc.), antioxidants, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, colorants (pigments, dyes, etc.), etc. Various additives may be blended.

The cavity ratio is preferably 15% (volume%) or more, more preferably 18% or more, still more preferably 20% or more, based on the volume of the polyester-based base material. When the cavity ratio is 15% or more, the cushioning property of the separator is improved, and the filler contained in the base film constituting the optical surface protective film or the polyester-based base material constituting the separator (for example, polyethylene terephthalate (PET)). It is possible to absorb the unevenness caused by the filler) and suppress the occurrence of glue dents caused by the separator or the like. Further, since the stiffness (rigidity) of the separator is lowered, the peelability of the separator is improved. From the viewpoint of the strength of the separator and the like, the cavity ratio is preferably 40% or less, more preferably 30% or less.

The shape of the cavity of the polyester-based base material is spherical, elliptical spherical, thread-like, or the like, and is preferably in a dispersed form. The dispersion diameter is preferably 0.01 to 100 μm, more preferably 0.05 to 30 μm. Within the above range, the separator is strong, has excellent cushioning properties, and is excellent in peelability of the separator, which is a preferable embodiment. The shape of the cavity can be observed from the cross section of the base material with a scanning electron microscope.

<Release layer>
The release layer has adhesiveness to the polyester-based substrate and peelability to the pressure-sensitive adhesive layer, and can be formed from the release agent composition. The release agent composition is not particularly limited, and for example, a silicone compound such as dimethylsiloxane or diphenylsiloxane, a long-chain alkyl compound such as a silicone resin, a fluororesin, or asioresin can be used.

Further, the release agent composition may contain other known additives, such as antistatic agents, colorants, powders such as pigments, surfactants, plasticizers, and tackifiers. , Low molecular weight polymers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, UV absorbers, polymerization inhibitors, silane coupling agents, inorganic or organic fillers, metal powders, particulates, etc. Can be added as appropriate depending on the intended use.

<Making a separator>
The separator is formed on the polyester-based substrate by using the release agent composition.

The method for forming the release layer on the polyester-based substrate is not particularly limited. For example, a solution of the release agent composition is applied to the substrate, and a polymerization solvent or the like is dried and removed to form the release layer. It is produced by forming it on a substrate. After that, curing may be performed for the purpose of adjusting the component transfer of the release layer. Further, when the release agent composition is applied onto the base material to prepare a release layer, one or more types other than the polymerization solvent may be contained in the release agent composition so that the release layer can be uniformly applied on the base material. A new solvent may be added.

Further, as the method for forming the release layer, a known method used for producing the release layer is used. Specific examples thereof include a roll coat, a gravure coat, a reverse coat, a roll brush, a spray coat, an air knife coat method, and an extrusion coat method using a die coater or the like.

The thickness of the release layer is typically 1 to 200 nm, preferably 5 to 100 nm, and more preferably 10 to 50 nm. If the thickness of the release layer is too small, the release effect of the release layer is weak and it becomes difficult to peel off the separator, which may make it difficult to attach the optical surface protective film. On the other hand, if it is too thick, it may affect the stainability of the pressure-sensitive adhesive layer of the optical surface protective film.

Examples of commercially available products of the separator include Crisper K7211-50 μm, Crisper K7211-38 μm (above, manufactured by Toyobo Corporation), PET50 (K2411) PAT18LK, PET50 (K2411) PAT1 9K (above, manufactured by Lintec Corporation), and the like. ..

<Attachment of optical surface protection film and separator>
The optical surface protective film with a separator of the present invention has a form in which a release layer of the separator is bonded to the surface of the pressure-sensitive adhesive layer of the optical surface protective film. A known method is used for bonding.

<Optical member>
In the present invention, the optical surface protective film obtained by peeling the separator from the surface of the pressure-sensitive adhesive layer of the optical surface protective film with a separator can be attached to the optical member to protect the optical member. Since the separator has excellent cushioning properties, dents are unlikely to occur, and the peelability is also good. Further, since the optical surface protective film has excellent appearance quality (appearance), it is processed, transported, and shipped. Since it can be used for surface protection applications (surface protection film), it is useful for protecting the surface of the optical member (polarizing plate, etc.).

Hereinafter, some examples related to the present invention will be described, but the present invention is not intended to be limited to those shown in such specific examples. In addition, "part" and "%" in the following description are based on weight unless otherwise specified. In addition, the blending amount (addition amount) in the table is shown.

In addition, each characteristic in the following description was measured or evaluated as follows.

<Measurement of cavity ratio of polyester base material constituting separator>
After taking a picture of the cross section of the polyester base material with a scanning electron microscope, the cavities in the cross section area are traced on tracing film, and the filled figure is image-processed with an image analyzer, and the cavity ratio (%) is the area ratio. This value was directly expressed as the cavity ratio (volume%).
-Scanning electron microscope used: S-510 scanning electron microscope manufactured by Hitachi, Ltd.-Image analysis processing device used: Luzex IID manufactured by Nireco Co., Ltd.

<Measurement of separator thickness>
The thickness of the separator (separator thickness) is the total thickness of the polyester-based base material and the release layer, and was measured using R1-205 manufactured by Ozaki Seisakusho Co., Ltd.

<Measurement of (meth) acrylic polymer glass transition temperature (Tg)>
The glass transition temperature (Tg) (° C.) was determined by the following formula using the following literature values as the glass transition temperature Tgn (° C.) of the homopolymer by each monomer.
Formula: 1 / (Tg + 273) = Σ [Wn / (Tgn + 273)]
(In the formula, Tg (° C.) is the glass transition temperature of the copolymer, Wn (-) is the weight fraction of each monomer, Tgn (° C.) is the glass transition temperature of the homopolymer by each monomer, and n is the type of each monomer. Represents.)
Reference value:
2-Ethylhexyl acrylate (2EHA): -70 ° C
Butyl acrylate (BA): -55 ° C
2-Hydroxyethyl acrylate (HEA): -15 ° C.
Acrylic acid (AA): 106 ° C
For reference values, refer to "Acrylic resin synthesis / design and new application development" (published by the Publishing Department of the Central Management Development Center).

<Measurement of weight average molecular weight (Mw) of (meth) acrylic polymer>
The weight average molecular weight (Mw) of the (meth) acrylic polymer used was measured using a GPC apparatus (HLC-8220 GPC) manufactured by Tosoh Corporation. The measurement conditions are as follows.
Sample concentration: 0.2% by weight (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow velocity: 0.6 ml / min
Measurement temperature: 40 ° C
column:
Sample column; TSKguardcolum SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column; TSKgel SuperH-RC (1)
Detector: Differential Refractometer (RI)
The weight average molecular weight was determined by polystyrene conversion value.

<Presence or absence of dents on the surface of the adhesive layer>
Under a dark room fluorescent lamp, the separator was peeled off from the surface of the pressure-sensitive adhesive layer of the optical surface protective film, light was reflected on the surface of the pressure-sensitive adhesive layer, and visually confirmed whether there were any dents. The case where there was no dent was marked as ◯, and the case where there was a dent was marked as x.

<Measurement of the trigger peeling force of the separator>
As shown in FIG. 2, the optical surface protective film 3 with a separator is cut into a size of 50 mm in width and 100 mm in length, and a double-sided tape 4 (manufactured by Nitto Denko Co., Ltd., No. 500) is attached to the glass 5 (S9213, The surface of the base film 22 constituting the optical surface protective film 3 with a separator was pressed onto the surface of the base film 22 (manufactured by Matsunami Glass Ind.) At a pressure of 0.25 MPa and a speed of 0.3 m / min.
Subsequently, the single-sided adhesive tape 6 (No. 720, manufactured by Nitto Denko KK, width 50 mm) was cut to a length of 50 mm. The adhesive surface of the single-sided adhesive tape 6 was crimped with a hand roller onto the separator 1 having a width of 50 mm of the optical surface protective film 3 with a separator so that the end portion protruded by 1 mm. This was allowed to stand for 10 seconds under the conditions of 23 ° C. and 50% RH. Then, when the single-sided adhesive tape 6 was peeled off in the 180 ° direction at a speed of 0.3 m / min by an autograph, the maximum stress applied at the beginning of the peeling was used as a trigger peeling force (N / 50 mm).

The trigger peeling force (pickup force) is 0.7 N / 50 mm or less, preferably 0.68 N / 50 mm or less, and more preferably 0.65 N / 50 mm or less. If the trigger peeling force exceeds 0.7 N / 50 mm, it takes time to peel the separator from the surface of the pressure-sensitive adhesive layer of the optical surface protective film when a thick separator is used, resulting in peelability and work. It is inferior in sex and is not preferable. On the other hand, if the trigger peeling force is too low, it may not be possible to sufficiently protect the surface of the pressure-sensitive adhesive layer of the optical surface protective film, so 0.2 N / 50 mm or more is preferable.

<Preparation of (meth) acrylic polymer (A)>
100 parts by weight of 2-ethylhexyl acrylate (2EHA), 4 parts by weight of 2-hydroxyethyl acrylate (HEA), 2, as a polymerization initiator, in four flasks equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. Add 0.2 parts by weight of 2'-azobisisobutyronitrile (AIBN) and 205 parts by weight of ethyl acetate, introduce nitrogen gas with gentle stirring, and keep the liquid temperature in the flask at around 63 ° C. The polymerization reaction was carried out for 4 hours to prepare a (meth) acrylic polymer (A) solution (about 35% by weight). The weight average molecular weight of the (meth) acrylic polymer (A) was 650,000, and the Tg was −68 ° C.

<Preparation of (meth) acrylic polymer (B)>
95 parts by weight of butyl acrylate (BA), 5 parts by weight of acrylic acid (AA), 2,2'-azo as a polymerization initiator in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. 0.1 part by weight of bisisobutyronitrile and 234 parts by weight of ethyl acetate were charged, nitrogen gas was introduced while gently stirring, and the polymerization reaction was carried out for 6 hours while keeping the liquid temperature in the flask at around 65 ° C. A meta) acrylic polymer (B) solution (30% by weight) was prepared. The weight average molecular weight (Mw) of the (meth) acrylic polymer (B) was 1.1 million, and the glass transition temperature (Tg) was −47 ° C.

[Preparation of acrylic adhesive (1) solution]
The above (meth) acrylic polymer (A) solution (35% by weight) was diluted with ethyl acetate to 29% by weight, and 500 parts by weight (solid content 100 parts by weight) of this solution was added as a cross-linking agent with a trifunctional isocyanate compound. Isocyanurate of a certain hexamethylene diisocyanate (coronate HX: C / HX, manufactured by Nippon Polyurethane Co., Ltd.) 4 parts by weight (solid content 4 parts by weight), dibutyltin dilaurate as a cross-linking catalyst (“Sn” in Table 2, 1% by weight) (Ethyl acetate solution) 1.5 parts by weight (solid content 0.015 parts by weight) was added, and the mixture was mixed and stirred for about 1 minute at about 25 ° C. to prepare an acrylic pressure-sensitive adhesive (1) solution.

[Preparation of acrylic adhesive (2) solution]
The above (meth) acrylic polymer (B) solution (30% by weight) was diluted with ethyl acetate to 29% by weight, and 500 parts by weight (solid content 100 parts by weight) of this solution was added as a cross-linking agent to an epoxy-based cross-linking agent ( 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent: 110, number of functional groups: 4, trade name "TETRAD-C": T / C, manufactured by Mitsubishi Gas Chemicals, Inc.) 6 parts by weight (solid) 6 parts by weight) was added, and the mixture was mixed and stirred to prepare a solution of the acrylic pressure-sensitive adhesive (2).

[Preparation of acrylic adhesive (3) solution]
The above (meth) acrylic polymer (A) solution (35% by weight) is diluted with ethyl acetate to 29% by weight, and an isocyanate-based cross-linking agent (isocyanate-based cross-linking agent) is added to 500 parts by weight (solid content 100 parts by weight) of this solution as a cross-linking agent. Isocyanurate of hexamethylene diisocyanate (trade name "Coronate HX": C / HX, manufactured by Nippon Polyurethane Co., Ltd.) 5 parts by weight (solid content 5 parts by weight), dibutyltin dilaurate (1 wt% ethyl acetate solution) 3 as a cross-linking catalyst 0.3 parts by weight (solid content 0.03 parts by weight), 0.3 parts by weight (solid content 0) of a polyoxyalkylene chain-containing compound (Aqualon HS-10, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) that does not contain the additive organopolysiloxane. .3 parts) was added, and the mixture was mixed and stirred to prepare an acrylic pressure-sensitive adhesive (3) solution.

<Example 1>
[Preparation of antistatic film]
Antistatic agent (manufactured by Solvex, microsolver RMd-142, mainly composed of tin oxide and polyester resin) 10 parts by weight is diluted with a mixed solvent consisting of 30 parts by weight of water and 70 parts by weight of methanol to prevent antistatic. A drug solution was prepared.
The obtained antistatic agent solution was applied onto a polyethylene terephthalate (PET) film (thickness: 38 μm) as a base film using a Meyer bar, and dried at 130 ° C. for 1 minute to remove the solvent. An antistatic layer (thickness: 0.2 μm) was formed to prepare an antistatic treated film.

[Manufacturing of optical surface protective film with separator]
The above acrylic pressure-sensitive adhesive (1) solution was applied to the surface of the antistatic treatment film opposite to the antistatic treatment surface, and heated at 130 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 15 μm. .. Next, the surface of the pressure-sensitive adhesive layer was treated with silicone on one side, Crisper K7211-50 μm (manufactured by Toyobo Co., Ltd., specific gravity of polyester-based base material: 1.1 g / cm ³ , cavity ratio of polyester-based base material). A silicone-treated surface (20%, thickness 50 μm) was used for bonding to prepare an optical surface protective film with a separator.

<Examples 2 to 5, Comparative Examples 1 to 4>
As shown in Table 2, the acrylic pressure-sensitive adhesive (1) solution used in Example 1 or, instead, the acrylic pressure-sensitive adhesive (2) solution or the acrylic pressure-sensitive adhesive (3) solution was used, and the table was used. An optical surface protective film with a separator was produced in the same manner as in Example 1 except that the separator described in 3 was used.

Tables 1 to 3 show the above-mentioned compounding contents, various measurements and evaluation results of the optical surface protective film with a separator according to Examples and Comparative Examples. The blending amount in the table indicates the active ingredient.

From Table 3 above, in all the examples, by setting the cavity ratio and the thickness of the polyester-based base material constituting the separator within a desired range, it is possible to obtain excellent peelability and workability, and further prevent the occurrence of dents. It could be confirmed. Further, in the examples, since no dents are generated on the surface of the pressure-sensitive adhesive layer, the optical surface protective film is attached to the adherend without air bubbles when the adhesive layer is attached to the adherend. It is possible to provide an optical surface protective film having excellent inspectability at the time of inspection. On the other hand, in Comparative Examples 1 to 3, since the cavity ratio of the polyester-based base material constituting the separator is not included in the desired range, the separator has strong stiffness (rigidity) and is inferior in peelability and workability. Since the thickness of the polyester-based base material was not included in the desired range, the cushioning property could not be exhibited, and the occurrence of dents due to the separator was confirmed.

The optical surface protective film with a separator disclosed herein is said to be used during manufacturing, transportation, etc. of an optical member used as a component of a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, or the like. It is suitable as a surface protective film for protecting an optical member. In particular, it is useful as an optical surface protection film applied to optical members such as polarizing plates (polarizing films) for liquid crystal display panels, wave plates, retardation plates, optical compensation films, brightness improving films, light diffusion sheets, and reflective sheets. Is.

1: Separator 2: Optical surface protective film 3: Optical surface protective film with separator 4: Double-sided adhesive tape 5: Glass 6: Single-sided adhesive tape 11: Polyester-based base material 12: Release layer 21: Adhesive layer 22: Base film

Claims (4)

An optical surface protective film having an adhesive layer on at least one side of the base film, and an optical surface protective film with a separator having a separator on the surface of the adhesive layer opposite to the surface in contact with the base film. hand,
The separator has a release layer and a polyester-based base material.
The polyester-based base material has a cavity and has a cavity.
The thickness of the polyester-based base material is 25 to 100 μm, and the thickness is 25 to 100 μm.
An optical surface protective film with a separator, wherein the 180 ° trigger peeling force of the separator with respect to the pressure-sensitive adhesive layer is 0.7 N / 50 mm or less.
The optical surface protective film with a separator according to claim 1, wherein the cavity ratio is 15% or more with respect to the volume of the polyester-based base material. The optical surface protective film with a separator according to claim 1 or 2, wherein the base film is a polyester film. The optical surface protective film with a separator according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing a (meth) acrylic polymer.

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