WO2010032583A1

WO2010032583A1 - Surface-protective film and laminate

Info

Publication number: WO2010032583A1
Application number: PCT/JP2009/064560
Authority: WO
Inventors: 克彦細越; 光則丸山
Original assignee: 株式会社きもと
Priority date: 2008-09-17
Filing date: 2009-08-20
Publication date: 2010-03-25
Also published as: TW201016822A; JPWO2010032583A1; JP6054591B2; KR101627882B1; CN102149778B; KR20110057210A; TWI555814B; CN102149778A

Abstract

A surface-protective film comprising a substrate and a pressure-sensitive adhesive layer formed on one side thereof, wherein the pressure-sensitive adhesive layer is such that the difference between storage modulus at 150°C and that at 20°C satisfies a prescribed relationship and that the temperature at which the tan δ is maximum is -5°C or below. The surface-protective film exerts excellent initial tackiness to the surface of an object to be protected, such as a metal sheet, a decorative laminated sheet, a plastic sheet, or a glass sheet, and exhibits little tack increase even after heat treatment, particularly even when used in a field accompanied with high-temperature heating. When the surface-protective film is peeled from an object protected therewith, the surface -protective film rarely leaves a pressure-sensitive adhesive residue on the surface of the resulting object. Further, the surface-protective film does not cause delamination phenomena such as lifting.

Description

Surface protective film and laminate

The present invention relates to a surface protective film used for temporarily protecting the surface of a metal plate, a decorative plate, a plastic plate, a glass plate, etc. during processing, transportation, storage, etc., and a laminate on which the surface protective film is adhered. About the body.

In general, as a surface protection film used to temporarily protect the surface of metal plates, decorative plates, plastic plates, glass plates, etc. during processing, transportation, storage, etc. There is known a pressure-sensitive adhesive layer provided with a pressure-sensitive adhesive as a main component and a crosslinking agent added thereto for crosslinking. (See Patent Document 1).

Japanese Unexamined Patent Publication No. 63-225677 (Example)

However, such a surface protective film has good adhesiveness at the initial stage of application, but the adhesiveness with time after application tends to increase. For this reason, the used surface protection film cannot be easily peeled off from the object to be protected, requiring labor for the peeling operation. In some cases, a part of the adhesive layer of the surface protection film remains on the surface of the object to be protected. And the surface protective film stretches and breaks.

In particular, an object to be protected with a surface protective film is exposed to a high temperature state of about 100 to 150 ° C., for example, in a thermoforming process or a drying process after painting, or in a medium temperature state of about 40 to 60 ° C. for a long time. When stored, the tackiness increases significantly over time.

Also, there is a problem that peeling phenomenon such as floating occurs due to heat treatment (particularly in the case of a high temperature state as described above) in the drying process after coating such as thermoforming.

Therefore, the present invention has excellent initial adhesiveness to the surface of an object to be protected such as a metal plate, a decorative plate, a plastic plate, and a glass plate, and when used in an application involving heat treatment, particularly high temperature heating, the adhesive strength even after the heat treatment. The surface protection film that prevents the adhesive from remaining on the surface of the object to be protected and does not cause a peeling phenomenon such as floating, and the laminate on which the surface protection film is adhered The purpose is to provide a body.

The surface protective film of the present invention is a surface protective film having an adhesive layer on one surface of a substrate, and the adhesive layer has a difference between the storage elastic modulus at 150 ° C. and the storage elastic modulus at 20 ° C. (1). The tan δ maximum temperature is satisfied, and the tan δ maximum temperature is −5 ° C. or lower.

[Equation 1] G ′ (150) −G ′ (20) ≧ 0 (1)
[Wherein G ′ (150) is a storage elastic modulus at 150 ° C., and G ′ (20) is a storage elastic modulus at 20 ° C. Further, tan δ is a value obtained by dividing the loss elastic modulus by the storage elastic modulus. ]

Also preferably, the adhesive layer is characterized in that tan δ at 100 ° C. to 150 ° C. is 0.1 or less.

Preferably, the surface protective film of the present invention is obtained by laminating a surface having an adhesive layer of the surface protective film and a stainless steel plate (SUS304 steel plate defined in JIS G4305) and leaving it in an environment of 150 ° C. for 30 minutes. After that, the adhesive strength of the surface protective film to the stainless steel plate (180-degree peeling adhesive strength in JIS Z0237: 2000) is 0.1 N / 50 mm to 1 N / 50 mm.

When the response of the stress to the sinusoidal strain of the viscoelastic body is expressed as a complex number, it is defined as in equation (2), where G ′ is the storage elastic modulus, G ″ is the loss elastic modulus, and G ^* is the complex elasticity. It is called rate.

[Formula 2] G ^* = G ′ + iG ″ (2)
[Wherein G ′ represents an elastic component of G, and G ″ represents a viscous component of G. ]

Further, the storage elastic modulus referred to in the present invention is related to the amount of energy stored when strain is applied to the viscoelastic body, and the loss elastic modulus is related to the loss due to heat of the energy. The complex elastic modulus is a physical property value representing the relationship between stress and strain in a viscoelastic body. These are determined by measuring dynamic viscoelasticity. The dynamic viscoelasticity referred to here is a viscoelastic behavior that appears when a regular vibration having a sinusoidal change is applied.

Tan δ is a ratio of loss elastic modulus to storage elastic modulus, and is a value expressed by loss elastic modulus / storage elastic modulus. The tan δ maximum temperature is the temperature (° C.) at which tan δ takes a maximum value.

The laminate of the present invention is characterized in that the surface having the pressure-sensitive adhesive layer of the surface protective film is stuck on the hard coat layer. Further, the hard coat layer has a contact angle with water of 110 degrees or less and a contact angle with kerosene of 50 degrees or less. The hard coat layer has a contact angle with water of 50 degrees or more and a wetting tension of 27 to 45 mN / m.

According to the present invention, since it is a surface protective film having an adhesive layer exhibiting specific physical properties on one surface of a substrate, initial adhesiveness to the surface of an object to be protected such as a metal plate, a decorative plate, a plastic plate, or a glass plate When it is used for applications involving heat treatment, especially high-temperature heating, there is little increase in adhesive strength even after heat treatment, and it is difficult for adhesive residue to remain on the surface of the object to be protected when peeling from the object. And the surface protection film which does not produce peeling phenomena, such as a float, can be provided. Provided is a surface protective film that is excellent in initial tackiness even when stuck to a hard coat layer, particularly a hard coat layer having specific surface properties, and that hardly causes adhesive residue on the hard coat layer even after heat treatment. be able to.

Hereinafter, embodiments of each component will be described.

The substrate used in the present invention is not particularly limited to transparent or opaque, and may be appropriately selected according to the use. However, if the material is transparent, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, Examples thereof include plastic films such as polycarbonate, polyethylene, polypropylene, polystyrene, triacetyl cellulose, acrylic, polyvinyl chloride, and norbornene compounds. Opaque materials include opaque substrates such as paper and synthetic paper, the above plastic film made opaque by including pigments, and the above plastic film provided with a colored layer having a concealing property Etc.

The thickness of the base material varies depending on the use and cannot be generally specified. However, in consideration of ease of handling, the lower limit is generally 2 μm or more, preferably 10 μm or more, and the upper limit is 300 μm or less, preferably about 125 μm or less. Conceivable.

Such a substrate is subjected to easy adhesion treatment such as plasma treatment, corona discharge treatment, deep ultraviolet irradiation treatment, sand blast treatment, or undercoat easy adhesion treatment layer in order to improve adhesion with the adhesive layer described later. May be provided.

Next, the adhesive layer will be described. The adhesive layer has the difference between the storage elastic modulus at 150 ° C. and the storage elastic modulus at 20 ° C. satisfying the above formula (1), and the tan δ maximum temperature is −5 ° C. or lower, preferably −10 ° C. or lower, and further −20 ° C. It is as follows.

Thus, when the difference between the storage elastic modulus at 150 ° C. and the storage elastic modulus at 20 ° C. satisfies the above formula (1) and the tan δ maximum temperature is −5 ° C. or lower, When used in applications involving heating, there is little increase in adhesion even after heat treatment, and it is difficult for the adhesive to remain on the surface of the protected object when peeling from the protected object, and peeling phenomenon such as floating occurs. There can be no surface protection film.

That is, the adhesive layer is such that the difference between the storage elastic modulus at 150 ° C. and the storage elastic modulus at 20 ° C. satisfies the above formula (1), so that the adhesive layer becomes too soft at high temperatures and Since it can be prevented from becoming too familiar, even when it is used for heat treatment, especially in applications involving high temperature heating of about 100 ° C to 150 ° C, there is little increase in adhesive strength even after heat treatment, and peeling from the object to be protected In this case, the adhesive residue on the surface of the object to be protected can hardly be left.

Furthermore, the adhesive layer has an initial tackiness by setting the tan δ maximum temperature to -5 ° C or lower, so it has excellent initial adhesiveness, and peeling phenomenon such as floating even when exposed to a high temperature of about 100 ° C to 150 ° C. Can be made difficult to occur.

Further, the adhesive layer preferably has a tan δ at 100 ° C. to 150 ° C. of 0.1 or less. By setting tan δ at 100 ° C. to 150 ° C. to 0.1 or less, the behavior of the elastic component in the adhesive layer appears stronger than the behavior of the viscous component. When peeling off, the adhesive residue on the surface of the object to be protected can be made more difficult. Moreover, although it changes with materials and shapes of a to-be-protected object, it exists in the tendency which can prevent that the initial adhesive force becomes high too much.

In addition, the adhesive layer preferably has an adhesive force with respect to the stainless steel plate after being left in an environment of 150 ° C. for 30 minutes between 0.1 N / 50 mm and 1 N / 50 mm. When the adhesive strength to the stainless steel plate after being left for 30 minutes in an environment of 150 ° C. is 0.1 N / 50 mm or more, peeling such as floating due to heat treatment in the drying process after thermoforming or painting The phenomenon can be made less likely to occur, and by setting it to 1 N / 50 mm or less, the peelability is good, and the workability and the handleability can be improved.

As the adhesive constituting such an adhesive layer, natural resin-based adhesives, synthetic resin-based adhesives and the like are used, and synthetic resin-based adhesives such as acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, etc. Are preferably used. Among them, since it has weather resistance, hardly causes cohesive failure, can easily control the adhesive force, and can adjust the performance of removability and reattachability, a crosslinkable adhesive is preferable. A crosslinkable acrylic pressure-sensitive adhesive is particularly preferably used because of easy handling. The crosslinking agent used for the adhesive layer is not particularly limited, and for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an imine crosslinking agent, and a metal chelate can be used.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is 1 μm to 30 μm, preferably 2 μm to 10 μm in consideration of tackiness, adhesive strength, handling property, economy, etc. at the initial stage and after heating.

In the adhesive layer, in addition to adhesives and crosslinking agents, pigments, dyes, colorants, matting agents, antistatic agents, flame retardants, fungicides, rust inhibitors, antibacterial agents, ultraviolet absorbers, light stabilizers, You may add additives, such as a heat stabilizer, antioxidant, a plasticizer, a leveling agent, a flow regulator, an antifoamer, a dispersing agent, a fluorescent whitening agent, a storage stabilizer, a silane coupling agent. However, the addition amount of these additives is preferably in a range that does not hinder the effect of the adhesive layer.

The surface protective film of the present invention as described above is prepared by preparing an adhesive layer coating solution by dissolving or dispersing the above-mentioned adhesive agent, crosslinking agent, and additives added as necessary in a solvent. The coating method of, for example, bar coater, die coater, blade coater, spin coater, roll coater, gravure coater, flow coater, spray, screen printing, etc., is applied onto the above-mentioned substrate, dried and cured by heating. It can be obtained by forming an adhesive layer. Further, from the viewpoint of handleability, it may be prepared by applying and drying on a substrate, and then providing a separator on the surface of the exposed adhesive layer and then curing by heating.

Further, the surface protective film of the present invention can also be obtained by applying the above-mentioned adhesive layer coating solution onto a separator in the same manner as described above, drying it, bonding it to a substrate, and then curing it by heating.

Examples of the method of using the surface protective film of the present invention include, for example, protection during the production of optical members such as polarizing plates, during the printing process, during the production of electronic circuit boards, and during the production of electronic components such as ceramic capacitors. can give.

As described above, the surface protective film of the present invention is a surface protective film having an adhesive layer on one surface of a substrate, and the adhesive layer has a storage elastic modulus at 150 ° C. and a storage elastic modulus at 20 ° C. Since the difference satisfies the above formula (1) and the tan δ maximum temperature is −5 ° C. or less, it has excellent initial adhesiveness to the surface of a protected object such as a metal plate, a decorative plate, a plastic plate, a glass plate, and heat treatment. In particular, when used in applications involving high-temperature heating, there is little increase in adhesive strength even after heat treatment, and it is difficult for adhesive residue to remain on the surface of the protected object when peeling from the protected object, and peeling such as floating The phenomenon can be made difficult to occur.

The laminate of the present invention is obtained by sticking the surface having the adhesive layer of the surface protective film to the object to be stuck.

Hereinafter, the hard coat layer used in various fields will be exemplified and described as the object to be attached. The hard coat layer as an example can be obtained by preparing a curable composition (paint), applying it to a desired application target, and curing it.

The curable composition that can be used in this example contains a resin component. The resin component includes one or both of a thermosetting resin and an ionizing radiation curable resin. Thermosetting resins and ionizing radiation curable resins include, for example, polyester resins, acrylic resins, acrylic urethane resins, polyester acrylate resins, polyurethane acrylate resins, epoxy acrylate resins, urethane resins, epoxy resins, and polycarbonates. Resin, melamine resin, phenol resin, silicone resin, fluorine resin and the like.

In particular, the resin component preferably contains at least an ionizing radiation curable resin from the viewpoint of excellent coating hardness (hard coat property) after curing. As the ionizing radiation curable resin, a photopolymerizable prepolymer that is crosslinked and cured by irradiation with ionizing radiation (ultraviolet rays or electron beams) can be used. In this example, the photopolymerizable prepolymer described later may be used alone, or two or more kinds may be used in combination.

The photopolymerizable prepolymer includes a cationic polymerization type and a radical polymerization type. Examples of the cationic polymerization type photopolymerizable prepolymer include epoxy resins and vinyl ether resins. Examples of the epoxy resin include bisphenol epoxy resin, novolac epoxy resin, alicyclic epoxy resin, and aliphatic epoxy resin. As the radical polymerization type photopolymerizable prepolymer, an acrylic prepolymer (hard prepolymer) having two or more acryloyl groups in one molecule and having a three-dimensional network structure by crosslinking and curing is hard coat property. In view of the above, it is particularly preferably used.

Examples of acrylic prepolymers include urethane acrylate, polyester acrylate, epoxy acrylate, melamine acrylate, polyfluoroalkyl acrylate, and silicone acrylate. The urethane acrylate prepolymer can be obtained, for example, by esterifying a polyurethane oligomer obtained by reaction of polyether polyol or polyester polyol with polyisocyanate by reaction with (meth) acrylic acid. Examples of the polyester acrylate-based prepolymer include esterification of a hydroxyl group of a polyester oligomer having hydroxyl groups at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid, or a polyvalent carboxylic acid. It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to an acid with (meth) acrylic acid. The epoxy acrylate prepolymer can be obtained, for example, by esterification by a reaction of an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolac epoxy resin with (meth) acrylic acid.

The acrylic prepolymer can be appropriately selected according to the type and application of the member to be coated. The acrylic prepolymer can be used alone, but it is preferable to add a photopolymerizable monomer in order to impart various performances such as improvement of cross-linking curability and adjustment of curing shrinkage.

Examples of the photopolymerizable monomer include monofunctional acrylic monomers (for example, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, butoxyethyl acrylate, etc.), bifunctional acrylic monomers (for example, 1,6-hexanediol diacrylate). , Neopentyl glycol diacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, hydroxypivalate ester neopentyl glycol diacrylate, etc.), trifunctional or higher acrylic monomers (eg dipentaerythritol hexaacrylate, trimethylpropane triacrylate, pentaerythritol tris) Acrylate etc.). “Acrylate” includes not only acrylate but also methacrylate. These photopolymerizable monomers may be used alone or in combination of two or more.

The total content (in terms of solid content) of the photopolymerizable prepolymer and the photopolymerizable monomer in the curable composition is preferably 40 to 99% by weight, more preferably 60 to 95% by weight, based on the total resin component. More preferably, it is 80 to 90% by weight.

When forming the above-mentioned hard coat layer and curing it by ultraviolet irradiation, additives such as a photopolymerization initiator, a photopolymerization accelerator, and an ultraviolet sensitizer are blended in the curable composition. It is preferable to do. The blending amount of these additives is usually selected in the range of 0.2 to 10 parts by weight with respect to 100 parts by weight of the total of the above-described photopolymerizable prepolymer and photopolymerizable monomer.

As the resin component, a thermosetting resin may be contained in the resin component instead of or in addition to the ionizing radiation curable resin. When the thermosetting resin is contained in the resin component, a thermopolymerizable monomer or prepolymer is used alone or in combination, and if desired, a thermopolymerization initiator, that is, a compound that generates active radical species by heating, or the like is contained.

Further, as the resin component, in addition to the thermosetting resin and ionizing radiation curable resin described above, other resins such as a thermoplastic resin may be included as long as the effects of the present invention are not impaired.

In addition, if necessary, an additive component may be added to the curable composition as long as the effects of the present invention are not impaired. Examples of the additive component include inorganic fine particles, resin fine particles, surface conditioners, lubricants, colorants, pigments, dyes, fluorescent brighteners, flame retardants, antibacterial agents, antifungal agents, ultraviolet absorbers, light stabilizers, heat Stabilizers, antioxidants, plasticizers, leveling agents, flow regulators, antifoaming agents, dispersants, storage stabilizers, crosslinking agents and the like can be mentioned. In particular, by adding inorganic fine particles or resin fine particles having a desired size, a mat hard coat layer having a desired shape can be formed. When such a hard coat layer is applied with a surface protective film and subjected to heat treatment (for example, 150 ° C., 90 minutes) due to the influence of the residual monomer component and the various additive components described above, for example, There is a tendency that glue remains more easily than when sticking to an object.

In particular, for the mat hard coat layer, when the adhesion of the adhesive layer is high with respect to the unevenness of the mat hard coat layer, the mat hard coat layer has a large surface area with the contacting adhesive layer, and therefore is subjected to heat treatment or the like. It tends to leave glue more than the clear hard coat layer. Also, when the adhesion of the adhesive layer is low with respect to the unevenness of the mat hard coat layer, the mat hard coat layer has a smaller surface area with the contacting adhesive layer, and therefore tends to be more likely to float than the clear hard coat layer. It is in. However, in the surface protective film of the present invention, since the adhesive layer has specific physical properties, even if it is attached to the mat hard coat layer, it is difficult for adhesive to remain even after heat treatment, and it is difficult for floating to occur. be able to.

Moreover, even if the surface property of the hard coat layer as an example of the object to be adhered is specific, the surface protective film of the present invention can be such that no adhesive residue is generated after the heat treatment. Specifically, as the hard coat layer, the contact angle with respect to water is smaller than a specific value, and the contact angle with respect to the soot oil is adjusted to be smaller than a specific value.

For example, when fingerprints adhere to the surface of the hard coat layer, the attached fingerprints are less noticeable (improving the degree of fingerprint visibility). Instead of imparting strong water and oil repellency to the coating surface, It is effective to impart excellent hydrophilicity and lipophilicity. And, by adjusting the surface properties of the hard coat layer so that each of the contact angle for water and the contact angle for oil is adjusted to be smaller than a specific value, it is possible to develop moderate hydrophilicity and lipophilicity. it can. If appropriate hydrophilicity and lipophilicity can be expressed on the surface of the hard coat layer, the contact area of the fingerprint component (consisting of an aqueous component and an oil component) with the coating surface will not be too small, and the fingerprint component will be coated. The surface can be appropriately wetted and spread. As a result, even when a fingerprint adheres to the surface of the hard coat layer, the attached fingerprint can be made inconspicuous (improvement in the difficulty of visually recognizing the fingerprint).

In addition to the adjustment described above, the contact angle with respect to water is adjusted to a predetermined angle or more, and the wetting tension is adjusted to a predetermined range, thereby improving the fingerprint visual difficulty and preventing the hard coat property from being lowered. In addition, the wiping property of the fingerprint after the fingerprint is attached becomes good, and the fingerprint component after wiping can be made inconspicuous.

In this example, it is preferable that the contact angle of the hard coat layer with respect to water is adjusted to 110 ° or less. More preferably, it is adjusted to 100 ° or less. By adjusting the contact angle with water to 110 ° or less, the contact area with water does not become too small, and the attached fingerprint can be made inconspicuous (improvement of fingerprint visibility difficulty).

In this example, it is preferable that the contact angle of the hard coat layer with the oil is adjusted to 50 ° or less. More preferably, it is adjusted to 40 ° or less. By adjusting the contact angle with the cocoon oil to 50 ° or less, the oily component in the fingerprint wets and spreads. For this reason, the attached fingerprint becomes inconspicuous (improvement of fingerprint visibility difficulty), and the fingerprint component after wiping can be inconspicuous.

In this example, the contact angle of the hard coat layer with respect to water is preferably adjusted to 50 ° or more. More preferably, it is adjusted to 60 ° or more, more preferably 70 ° or more, and particularly preferably 80 ° or more. By adjusting the contact angle with water to 50 ° or more, the contact area with water does not become too large. As a result, the aqueous component in the fingerprint is easily separated and the fingerprint wiping property is improved. That is, in this example, by adjusting the contact angle of the hard coat layer with respect to water within a predetermined range, in addition to the improvement in the difficulty of visually recognizing the fingerprint, the wiping property of the fingerprint is also improved.

Note that the values of the contact angle with respect to water and the contact angle with respect to bran oil are both values measured by a method based on JIS-R3257 (1999).

In this example, it is preferable that the wetting tension of the hard coat layer is adjusted to 27 mN / m or more. More preferably, it is adjusted to 30 mN / m or more. The wetting tension of the hard coat layer is preferably adjusted to 45 mN / m or less. More preferably, it is adjusted to 40 mN / m or less, more preferably 38 mN / m or less. By adjusting the wetting tension of the hard coat layer within a predetermined range, the fingerprint wiping property can be improved.

The value of the wetting tension is a value measured by a method in accordance with JIS-K6768 (1999).

A hard coat layer having such surface physical properties is obtained by blending a compound having a HLB value by the Griffin method within a specified range (nonionic compound) as an additive component to the curable composition of the hard coat layer described above. Can do. Examples of such compounds include nonionic compounds having an HLB value by the Griffin method of 2 or more, preferably 5 or more, more preferably 10 or more, for example 18 or less, preferably 15 or less. By blending a nonionic compound in which the HLB value is appropriately adjusted, it becomes easy to adjust the contact angle of the hard coat layer with water, the contact angle with kerosene, and the wetting tension within the predetermined ranges described above.

A nonionic compound is a generic term for compounds that are soluble in water and do not exhibit ionic properties, but are composed of a combined bond of a hydrophobic group (lipophilic group) and a hydrophilic group.

Such compounds include at least hydrophilic groups (eg, polyalkylene oxide, hydroxyl group, carboxyl group, sulfonyl group, phosphate, amino group, isocyanate group, glycidyl group, alkoxysilyl group, ammonium salt, various metal salts, etc.). A compound having at least one kind, and examples thereof include ethoxylated glycerin triacrylate, ethoxylated bisphenol A diacrylate, polyethylene glycol diacrylate, polyether-modified acrylate, and polyhydroxy-modified acrylate. Among these, polyethylene glycol diacrylate is preferably used from the viewpoints of solubility in a solvent and handleability.

Moreover, fatty acid esters and polyethers can also be used as nonionic compounds.

Examples of the fatty acid ester include fatty acid esters obtained by condensation of a monohydric alcohol or a dihydric or higher polyhydric alcohol and a fatty acid, such as propylene glycol monostearate, propylene glycol monolaurate, diethylene glycol monostearate, diethylene glycol. Examples thereof include monolaurate, glycerol monostearate, sorbitan sesquioleate, sorbitan monooleate, sorbitan monostearate, sorbitan monopalmitate, sorbitan monolaurate, and the like. Moreover, polyoxyalkylene addition fatty acid ester is also mentioned as fatty acid ester.

In addition, you may mix | blend the nonionic compound which addition-polymerized the alkylene oxide to fatty acid ester. As the alkylene oxide to be subjected to addition polymerization, ethylene oxide or propylene oxide is suitable. Each of ethylene oxide and propylene oxide may be subjected to addition polymerization alone or may be copolymerized.

Examples of the polyoxyalkylene-added fatty acid ester include polyoxyethylene hydrogenated castor oil, polyoxyethylene glycerol monostearate, polyoxyethylene (4) sorbitan monostearate, polyoxyethylene (20) sorbitan monostearate, Polyoxyethylene (4) sorbitan tristearate, polyoxyethylene (5) sorbitan monooleate, polyoxyethylene (5) sorbitan monooleate, polyoxyethylene (20) sorbitan trioleate, polyoxy Ethylene (4) sorbitan monolaurate, polyoxyethylene glycol 400 monooleate, polyoxyethylene glycol 400 monomonostearate Ether, polyethylene glycol 400 monolaurate, polyoxyethylene (4) sorbitan monolaurate and the like.

In this example, polyoxyethylene cholesteryl ether, polyoxyethylene decyl tetradecyl ether, or the like may be used as a compound other than fatty acid ester or polyether.

The content of the compound having an HLB value in a predetermined range by the Griffin method is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, more preferably 1 part by weight or more with respect to 100 parts by weight of the resin component. It is preferably 60 parts by weight or less, more preferably 15 parts by weight or less, and still more preferably 10 parts by weight or less. By setting the lower limit of the content of this compound to 0.1 parts by weight, it becomes easy to adjust the contact angle of the hard coat layer with water, the contact angle with kerosene, and the wetting tension to the predetermined ranges described above. Moreover, it can prevent that the hardness (hard-coat property) of the surface of a hard-coat layer falls by making the upper limit of content of this compound into 60 weight part. By blending an appropriate amount, it is expected that the fingerprint wiping property of the hard coat layer is further improved.

The hard coat layer preferably further has a pencil scratch value adjusted to H or higher. More preferably, it is adjusted to 2H or more. By adjusting the pencil scratch value to a predetermined value or more, it is possible to effectively prevent the surface of the hard coat layer from being scratched without improving the degree of difficulty in visually recognizing the fingerprint and deteriorating the fingerprint wiping property. The pencil scratch value is a value measured by a method according to JIS-K5600-5-4 (1999).

The hard coat layer preferably further has a refractive index adjusted to 1.45 to 1.65. More preferably, it is adjusted to 1.46 to 1.52. By adjusting the refractive index value within a predetermined range, the difference between the refractive index of the hard coat layer and the refractive index of the fingerprint component can be reduced. As a result, when a fingerprint adheres to the hard coat layer, the attached fingerprint becomes more inconspicuous (further improvement in the difficulty of visually recognizing the fingerprint), and the fingerprint component after wiping can be made inconspicuous.

The thickness of the hard coat layer is preferably about 0.1 μm or more and 30 μm or less. By setting the thickness of the hard coat layer to 0.1 μm or more, a film having sufficient hardness can be obtained. On the other hand, even if the thickness of the hard coat layer exceeds 30 μm, the coating hardness does not improve further. Further, when the thickness of the hard coat layer is increased, curling due to contraction of the coating tends to occur. Accordingly, the thickness is preferably 30 μm or less from the viewpoint of economy and curl prevention. In this example, the hard coat layer may be a thin film having a thickness of about 10 μm or less, and further about 5 μm or less. Even if it is a thin film, necessary and sufficient performance is ensured.

In addition, in order to obtain the above-mentioned surface characteristics, the surface of the hard coat layer may be subjected to a surface treatment such as a plasma treatment, a corona discharge treatment, or a deep ultraviolet irradiation treatment.

The hard coat layer having such surface properties is more susceptible to additive components and surface treatment than the above-described hard coat layer. It tends to be easy to do. However, in the surface protective film of the present invention, since the adhesive layer has specific physical properties, even if it is attached to a hard coat layer having such specific surface physical properties, it is difficult for adhesive residue to remain after heat treatment. Can be.

The curable composition is usually realized in the form of a paint. In the case of an organic solvent-based paint, it may be appropriately selected depending on the type of resin component, but after dissolving or dispersing the above-described resin component (additional component further if necessary) with a diluting solvent such as an organic solvent, A curable composition can be manufactured by adding an additive as needed.

As an object to be coated, it is a base material that is desired to have an effect of improving hard coat properties (abrasion resistance) and fingerprint visibility difficulty. The aspect of the base material that can be used in this example is not particularly limited, and may have any thickness such as a film shape, a sheet shape, or a plate shape. Further, the surface of the substrate may have, for example, an uneven shape or a three-dimensional shape having a three-dimensional curved surface.

The material of the substrate is not particularly limited and may be a hard substrate such as a glass plate, but in this example, a flexible resin substrate is preferable. The kind of resin which comprises a resin base material is not specifically limited. For example, as a resin in the case of forming a resin substrate in the form of a film or a sheet, for example, acrylic, polycarbonate, polyvinyl chloride, polyester, polypropylene, polyethylene, acetylcellulose, cycloolefin, and the like can be mentioned. On the other hand, examples of the resin when the resin base material is formed in a plate shape include acrylic, polycarbonate, polyvinyl chloride, and the like.

In addition, an easy adhesion treatment may be performed on the surface of the base material for the purpose of improving the adhesion with the hard coat layer composed of a cured product of the curable composition. Examples of the easy adhesion treatment include plasma treatment, corona discharge treatment, deep ultraviolet irradiation treatment, and formation of an undercoat easy adhesion layer.

Application (coating) of the curable composition to the object to be applied may be performed by a conventional method, for example, bar coating, die coating, blade coating, spin coating, roll coating, gravure coating, flow coating, dip coating, spray coating, screen. Examples include printing and brushing. It is applied so that the thickness of the coated film after application is preferably about 0.1 to 30 μm after drying and curing described below. When the curable composition is applied to the application target, the coated film is preferably dried at about 50 to 120 ° C.

Curing of the curable composition can be performed by irradiating the coated film after application with heat curing and / or ionizing radiation (light).

In the case of heat, for example, an electric heater, an infrared lamp, hot air, or the like can be used as the heat source. In the case of ionizing radiation (light), the radiation source is not particularly limited as long as the curable composition applied to the substrate can be cured in a short time. For example, examples of infrared ray sources include lamps, resistance heating plates, and lasers. Examples of the visible light source include sunlight, a lamp, a fluorescent lamp, and a laser. Ultraviolet (ionizing radiation) radiation sources include ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arcs, metal halide lamps, and the like. Ultraviolet rays in a wavelength region of 100 nm to 400 nm, preferably 200 nm to 400 nm, emitted from such an ultraviolet ray source are irradiated. Examples of the electron beam (ionizing radiation) source include scanning and curtain electron beam accelerators. An electron beam having a wavelength region of 100 nm or less emitted from such an electron beam accelerator is irradiated.

The dose of ionizing radiation varies depending on the type of ionizing radiation. For example, in the case of ultraviolet rays, the amount of light is preferably about 100 to 500 mJ / cm ² , and in the case of electron beams, it is preferably about 10 to 1000 krad.

The hard coat layer produced as described above is used in applications requiring improvement in hard coat properties (scratch resistance) and fingerprint visibility difficulty, particularly various displays (for example, plasma display panel PDP, cathode ray tube CRT, Hard coats for liquid crystal displays (LCDs, electroluminescence displays ELD, etc.); for showcases, watch and instrument cover glasses; for touch surfaces of touch panel electronic devices such as bank ATMs and ticket vending machines Is preferably used.

Electronic devices include information processing apparatuses such as mobile phones having the above-mentioned various displays (including personal portable information terminals incorporating PDA (Personal Digital Assistants) functions) and personal computers. is there.

Hereinafter, the present invention will be further described with reference to examples. “Parts” and “%” are based on weight unless otherwise specified.

[Examples 1 to 3 and Comparative Examples 1 to 4]
As a base material, on one side of a 25 μm-thick polyethylene terephthalate film (Lumirror S28: Toray Industries, Inc.), a coating solution for adhesive layers (Examples 1 to 3 and Comparative Examples 1 to 4) having the formulation shown in Table 1 was applied as a bar coater. Each was coated by the method, and dried at 90 ° C. for 1.5 minutes to form a pressure-sensitive adhesive layer having a dry film thickness of 2.5 μm, which was then bonded to a separator (MRF: Mitsubishi Chemical Polyester Film Co., Ltd.) to improve handling. . Next, curing was performed in an environment of 60 ° C. for 48 hours to prepare surface protective films of Examples 1 to 4 and Comparative Examples 1 to 4.

For the adhesive layers obtained in the examples and comparative examples of Table 1, (1) storage elastic modulus at 150 ° C. and 20 ° C., tan δ maximum temperature, and tan δ at 100 ° C. to 150 ° C. were measured. Moreover, about the surface protection film obtained by the Example and the comparative example, (2) initial stage adhesive force, (3) adhesive force after a heating, (4) adhesive residue, (5) floating was evaluated. The results are shown in Table 2.

(1) Storage elastic modulus at 150 ° C. and 20 ° C., tan δ maximum temperature, tan δ at 100 ° C. to 150 ° C.
A predetermined amount of the pressure-sensitive adhesive, curing agent, and solvent of the formulations shown in Table 1 were weighed, mixed and sufficiently stirred. It transferred to another container so that the coating film thickness after drying might be set to about 1 mm, and drying and curing were performed at 40 degreeC for 4 days. Thereafter, only the coating film was taken out from the container to prepare a measurement sample.

Using a viscoelasticity measuring device (Physica MCR301: Anton Paar), by measuring the dynamic viscoelasticity of the measurement sample, the storage elastic modulus at 150 ° C. and 20 ° C., the tan δ maximum temperature, and the tan δ at 100 ° C. to 150 ° C. Asked. The measurement conditions were a strain of 0.1%, a frequency of 1 Hz, and a temperature range of −30 ° C. to 160 ° C.

(2) Initial adhesive strength The surface protection films of Examples and Comparative Examples were cut into a size of 50 mm wide × about 200 mm long so that the length direction was the coating direction, and test specimens were prepared. Next, the test piece was affixed to a stainless steel plate (SUS304 steel plate specified in JIS G4305) and allowed to stand in an environment of 23 ° C. and 50% RH for 1 hour. HTM-100: Orienttech Co.) was used to measure 180 ° peel strength.

(3) Adhesive strength after heating A test piece was prepared in the same manner as in (2), attached to a stainless steel plate, left in an environment of 23 ° C. and 50% RH for 30 minutes, and then left in an environment of 150 ° C. for 30 minutes. Further, after being left for 30 minutes in an environment of 23 ° C. and 50% RH, the adhesive strength was measured by peeling 180 degrees in the same manner as in (2).

(4) Adhesive residue After measuring the adhesive force after heating of (3), the adhesive residue was evaluated by visually observing the state of the stainless steel plate. The evaluation was “○” when there was no adhesive residue on the stainless steel plate, “△” when there was adhesive residue on a part of the stainless steel plate, and stainless steel caused cohesive failure between the stainless steel plate and the base material. A piece of glue remaining on almost the entire surface of the board was designated as “x”.

(5) Float In measuring the adhesive strength after heating in (3), after leaving the stainless steel plate with the test piece stuck in an environment of 150 ° C. for 30 minutes, it was left in an environment of 23 ° C. and 50% RH for 30 minutes. In doing so, it was visually evaluated whether or not floating occurred from the stainless steel plate. “○” indicates that the test piece and the stainless steel plate are bonded to each other, and no floating occurs. “△” indicates that the area where the test piece is in close contact with the stainless steel plate is larger than the peeled area. The case where the area peeled off from the plate was larger than the area in close contact with each other was designated as “x”.

From Table 2, in the surface protective films of the examples, the difference between the storage elastic modulus at 150 ° C. and the storage elastic modulus at 20 ° C. of the adhesive layer is greater than 0, satisfies the above formula (1), and the tan δ maximum temperature is − It was 5 ° C or lower. For this reason, it has excellent initial adhesiveness, and there is little increase in adhesive force even after heat treatment at 150 ° C. for 30 minutes, there is no adhesive residue on the surface when peeling from the stainless steel plate, and it is difficult for floating to occur. It was. In addition, the adhesive strength after heating (180-degree peeling adhesive strength according to JIS Z0237: 2000) was 0.1 N / 50 mm to 1 N / 50 mm, so that the peelability was good.

In the surface protective films of Comparative Examples 1 and 2, the tan δ maximum temperature of the adhesive layer was −5 ° C. or lower, but the tan δ at 100 ° C. to 150 ° C. was greater than 0.1, and the storage elastic modulus at 150 ° C. Since the difference from the storage elastic modulus at 20 ° C. is less than 0 and does not satisfy the above formula (1), the float does not occur, but the initial adhesiveness is high, and the adhesive strength is also after heat treatment at 150 ° C. for 30 minutes. As a result, the adhesive remained on the surface when peeling from the stainless steel plate. Moreover, since the adhesive strength after heating (180 degree peeling adhesive strength in JIS Z0237: 2000) was 1 N / 50 mm or more, the peelability was poor.

In the surface protective film of Comparative Example 3, the difference between the storage elastic modulus at 150 ° C. and the storage elastic modulus at 20 ° C. was smaller than 0, but the tan δ maximum temperature of the adhesive layer was higher than −5 ° C. I have. For this reason, there was no glue residue.
In the surface protective film of Comparative Example 4, since the tan δ maximum temperature of the adhesive layer was −5 ° C. or lower and tan δ at 100 ° C. to 150 ° C. was 0.1 or lower, no floating occurred and the initial adhesiveness was increased. However, good results were obtained. However, since the difference between the storage elastic modulus at 150 ° C. and the storage elastic modulus at 20 ° C. is smaller than 0 and does not satisfy the above formula (1), the adhesive strength after the heat treatment is increased, and peeling from the stainless steel plate In this case, the adhesive remained on the surface.

[Example 4]
A hard coat film (KB film GN7B: having a clear hard coat layer made of an ionizing radiation curable resin on one surface of a substrate and a mat hard coat layer made of silica fine particles and an ionizing radiation curable resin on the other surface. Kimotosha) was prepared. Next, the surface which has the adhesion layer of the surface protection film of Example 1 was stuck on the clear hard-coat layer of the prepared hard coat film, and the laminated body of Example 4 was produced. The clear hard coat layer had a contact angle with water of 62 degrees, a contact angle with cocoon oil of 31 degrees, and a wetting tension of 23 mN / m or less.

[Example 5]
The surface having the adhesive layer of the surface protective film of Example 1 was stuck on the matte hard coat layer of the hard coat film of Example 4 to produce the laminate of Example 5. The mat hard coat layer has a contact angle with water of 79 degrees, a contact angle with cocoon oil of 34 degrees, and a wetting tension of 23 mN / m or less. The arithmetic average roughness in JIS B0601: 2001 is 0.12 ± 0.00. It was 04 μm.

[Example 6]
Prepare a hard coat film (KB film AFP: Kimoto Co., Ltd.) having a hard coat layer with a contact angle with water of 76 degrees, a contact angle with kerosene of 36 degrees, and a wetting tension of 32 mN / m on one side of the substrate. did. Next, the surface which has the adhesion layer of the surface protection film of Example 1 was stuck on the hard-coat layer of the prepared hard-coat film, and the laminated body of Example 6 was produced.

[Comparative Examples 5 to 7]
In the same manner as in Examples 4 to 6, except that the laminates of Examples 4 to 6 were changed to the surface protective film of Comparative Example 4 instead of the surface protective film of Example 1, Comparative Examples 5 to 7 A laminate was produced.

For the laminates obtained in Examples 4 to 6 and Comparative Examples 5 to 7, when the surface protective film was peeled from the hard coat layer, (6) initial adhesive strength, (7) adhesive strength after heating, ( 8) The adhesive residue and (9) floating were evaluated. The results are shown in Table 3.

(6) Initial adhesive strength The laminates obtained in Examples 4 to 6 and Comparative Examples 5 to 7 were cut into a size of 50 mm width × about 200 mm length, and a test piece was prepared at 23 ° C. and 50% RH. After leaving for 1 hour in the environment of, peel the surface protective film from the hard coat layer by 180 degrees using a Tensilon universal tensile tester (Tensilon HTM-100: Orientec Co., Ltd.) according to JIS Z0237: 2000. The peel strength was measured.

(7) Adhesive strength after heating A test piece was prepared in the same manner as in (6), left in an environment of 23 ° C. and 50% RH for 30 minutes, then left in an environment of 150 ° C. for 30 minutes, and further 23 ° C. After leaving for 30 minutes in an environment of 50% RH, the adhesive strength was measured by peeling 180 degrees in the same manner as in (6).

(8) Adhesive residue For the laminates of Examples 4 to 6 and Comparative Examples 5 to 7, a test piece was cut to the size of A-4 and allowed to stand in an environment of 23 ° C. and 50% RH for 30 minutes. Thereafter, the film was left for 90 minutes in an environment of 150 ° C., and further left for 30 minutes in an environment of 23 ° C. and 50% RH, and then the surface protective film was peeled off from the hard coat layer by hand. Evaluation is visually observed, and “XX” indicates that the adhesive remains on the entire surface of the hard coat layer, and “XX” indicates that the adhesive remains on the hard coat layer. Although it is difficult to understand, it is observed with a magnifying glass (25 × 25 times), and “△” indicates that there is a fine point residue (about 10 μm × 20 μm) on the hard coat layer. A sample with almost no adhesive residue was designated as “◯”.

(9) Lifting In the measurement of the adhesive strength after heating in (7), the test piece was left in the environment of 150 ° C. for 30 minutes and then left in the environment of 23 ° C. and 50% RH for 30 minutes. It was visually evaluated whether or not the float was generated from the coat layer. “○” indicates that the test piece and the hard coat layer are bonded to each other and no floating occurs, and “△” indicates that the area where the test piece is in close contact with the hard coat layer is larger than the peeled area. “×” indicates that the area peeled off from the hard coat layer was larger than the adhered area.

From Table 3, the laminates of the examples all had excellent initial tackiness with respect to the hard coat layer, and there was little increase in the adhesive strength even after heat treatment at 150 ° C. for 30 minutes, and no floating occurred. .

Further, in the laminates of Examples 4 and 5, when the surface protective film was peeled off from the hard coat layer after the heat treatment at 150 ° C. for 90 minutes, the hard coat layer did not visually recognize the adhesive residue, and was observed with a loupe. There was almost no fine glue residue.

In addition, the laminate of Example 6 had specific physical properties when the surface protective film was peeled off from the hard coat layer after 150 ° C. and 90 minutes of heat treatment. Although the evaluation of the adhesive residue was inferior compared with the hard coat layer of the laminate, the adhesive residue could not be visually confirmed, and a fine adhesive residue could be confirmed with a magnifying glass.

On the other hand, in the laminate of the comparative example, since the tan δ maximum temperature of the adhesive layer was −5 ° C. or lower and tan δ at 100 ° C. to 150 ° C. was 0.1 or lower, no float occurred and the initial adhesiveness was too high. Good results were obtained. However, the adhesive layer of the surface protective film had a difference between the storage elastic modulus at 150 ° C. and the storage elastic modulus at 20 ° C. smaller than 0 and did not satisfy the above formula (1). When the surface protective film was peeled off from the hard coat layer after the heat treatment at 150 ° C. for 90 minutes, adhesive residue clearly visible was generated in various places on the hard coat layer.

Further, in the laminate of Comparative Example 7, since the hard coat layer had specific physical properties, when the surface protective film was peeled off from the hard coat layer after heat treatment at 150 ° C. for 90 minutes, it can be clearly seen visually. The adhesive residue was generated on the entire surface of the hard coat layer.

As described above, the surface protective film used in the laminate of the example is compared with the surface protective film used in the laminate of the comparative example, even when the object to be protected is various hard coat layers, It exhibits extremely excellent performance such as moderate initial tackiness, suppression of increase in adhesive strength after heat treatment, anti-floating property, and anti-glue property.

Claims

A surface protective film having an adhesive layer on one surface of a substrate, wherein the adhesive layer has a difference between a storage elastic modulus at 150 ° C. and a storage elastic modulus at 20 ° C. satisfying the formula (1), and a tan δ maximum temperature A surface protective film characterized by having a temperature of −5 ° C. or lower.
[Equation 1] G ′ (150) −G ′ (20) ≧ 0 (1)
[Wherein G ′ (150) is a storage elastic modulus at 150 ° C., and G ′ (20) is a storage elastic modulus at 20 ° C. Further, tan δ is a value obtained by dividing the loss elastic modulus by the storage elastic modulus. ]
2. The surface protective film according to claim 1, wherein the adhesive layer has a tan δ at 100 ° C. to 150 ° C. of 0.1 or less.
It is a surface protection film of Claim 1 or 2, Comprising: The surface which has the adhesion layer of the said surface protection film, and a stainless plate (SUS304 steel plate prescribed | regulated to JISG4305) are bonded, and it is 30 degreeC in environment of 30 degreeC. A surface protective film characterized in that the adhesive strength of the surface protective film to the stainless steel plate (180 ° peel-off adhesive strength in JIS Z0237: 2000) is 0.1 N / 50 mm to 1 N / 50 mm after standing for a minute.
A laminate comprising a surface having an adhesive layer of the surface protective film according to any one of claims 1 to 3, which is adhered to the hard coat layer.
The laminate according to claim 4, wherein the hard coat layer has a contact angle with respect to water of 110 degrees or less and a contact angle with respect to soot oil of 50 degrees or less.
The laminate according to claim 5, wherein the hard coat layer has a contact angle with water of 50 degrees or more and a wetting tension of 27 to 45 mN / m.