JP6046500B2 - Protection sheet for chemical treatment - Google Patents

Description

  The present invention relates to a protective sheet for chemical treatment, and more particularly to a protective sheet for chemical treatment that masks a non-treatment target portion (a portion where the influence of the chemical solution is to be excluded) when an adherend is treated with the chemical solution.

  When an adherend (material to be treated) is treated with a chemical solution, the pressure-sensitive adhesive sheet for masking a non-treatment target portion (a portion where the influence of the chemical solution is to be excluded) of the adherend is typically a film. The pressure-sensitive adhesive (pressure-sensitive adhesive layer) and a base material that supports the pressure-sensitive adhesive are used, and the pressure-sensitive adhesive is attached to an adherend and used. Such an adhesive sheet for chemical treatment (hereinafter also referred to as “chemical treatment protective sheet” or simply “protective sheet”) is, for example, glass thickness adjustment or removal of burrs formed on the cut end face of glass. Etching process that dissolves glass with chemical solution (etching solution), etching process that partially corrodes metal surface with chemical solution (etching solution), circuit board (printed circuit board, flexible printed circuit board (FPC), etc.) It can be suitably used in a plating process or the like in which the connection terminal portion is partially plated with a chemical solution (plating solution). Patent documents 1-3 are mentioned as literature about this kind of technique.

JP 2010-53346 A Japanese Patent Laid-Open No. 2003-82299 JP 2009-209233 A

  The protective sheet for chemical solution treatment is also referred to as a surface of the protective sheet (a surface directly exposed to the chemical solution, that is, a surface opposite to the side attached to the adherend) or an outer edge (hereinafter referred to as an end surface or a side surface). ) To prevent the intrusion of the chemical liquid from (i.e., chemical liquid intrusion prevention (sealability)).

  Here, the infiltration of the chemical solution from the outer edge of the protective sheet can also occur from the interface between the adhesive of the protective sheet and the adherend. In order to prevent such intrusion from the interface, the property (adhesion) that the adhesive of the protective sheet adheres to the surface of the adherend without any gap is important. However, if an adhesive with high peel strength (adhesive strength) is used to improve the adhesion to the surface of the adherend, peeling workability when peeling off the protective sheet that has become unnecessary after chemical treatment is removed. Decreases. For example, the protective sheet itself is easily broken at the time of peeling or the adhesive of the protective sheet remains on the adherend surface (so-called adhesive residue). In addition, there is a concern that the load on the adherend during peeling may increase the adherend or the structure (for example, ITO film) on the surface. From these circumstances, when a protective sheet having a higher peel strength (heavy peel) is used, the efficiency of the peel work tends to be reduced because the peel work needs to be performed with more care.

  Then, this invention aims at provision of the protective sheet for chemical | medical solution processing which can make the chemical solution penetration prevention property and the peeling workability | operativity from a to-be-adhered body compatible at high level.

The protective sheet for chemical treatment provided by this specification includes a base material and an adhesive layer provided on one side of the base material. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (also referred to as a pressure-sensitive adhesive; the same shall apply hereinafter) is typically an acrylic pressure-sensitive adhesive mainly composed of an acrylic polymer. The protective sheet is 30 minutes after stuck to a glass plate in a peel angle of 180 °, it is preferable slow peel strength _{P L} measured at a tensile rate of 300 mm / min condition is 0.1 N / 20 mm or more. Further, the protective sheet is 30 minutes after stuck to a glass plate in a peel angle of 180 °, it is preferable tensile speed 10 m / fast peel strength is measured in minutes condition P _H is less than 3N / 20 mm.

In the art disclosed herein, a low speed peel strength P _L indicates the degree of peeling difficulty of the protective sheet (resistance) against the stress applied relatively slowly, as a characteristic associated with adhesion of the adhesive to the adherend Can be grasped. On the other hand, high-speed peel strength P _H as the peel strength that assumes cleanly peeled to the scene from (adherend after being chemical treatment for example, paste the protective sheet) the protective sheet has become unnecessary adherend Can be grasped.

It said protective sheet (typically adherend having a surface made of polar materials such as glass) adherend to the surface of a good low-speed peel strength P _L is 0.1 N / 20 mm or more Shows adhesion. Therefore, it is possible to effectively prevent the chemical solution from entering from the interface between the pressure-sensitive adhesive and the adherend, and the chemical solution penetration preventing property is excellent. Further, since the high-speed peel strength P _H is suppressed below 3N / 20 mm, the protective rupture of the sheet (tear) or adhesive residue does not easily occur upon the release of the protective sheet from the adherend, applied to the adherend The load is also small. Accordingly, the peeling workability is excellent. And since the gel fraction of an adhesive exists in the range of 25 mass% or more and 70 mass% or less, chemical | medical solution penetration | invasion prevention property and peeling workability | operativity can be made compatible with balance.

The protective sheet preferably has a ratio of the low-speed peel strength P _{L to} the high-speed peel strength P _H (P _L / P _H ) greater than 0.5. Such a protective sheet is lightly peeled at a high speed while being peeled off at a low speed. For this reason, for example, even if the gel fraction of the pressure-sensitive adhesive is less than 60% by mass (typically greater than 25% by mass and less than 60% by mass) in order to improve adhesion, the protective sheet breaks when the protective sheet is peeled off. And adhesive residue are less likely to occur, and the load on the adherend is small. Therefore, the chemical solution intrusion prevention property and the peeling workability can be achieved at a higher level.

In a preferred embodiment of the technology disclosed herein, the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing an acrylic polymer and a release adjusting agent. Here, the release modifier is included in the pressure-sensitive adhesive composition, whereby the low-speed peel strength P _L and the high-speed peel strength P _{H of} the protective sheet (pressure-sensitive adhesive sheet) provided with the pressure-sensitive adhesive layer formed from the composition. And in other words (in other words, the value of P _L / P _H ). Protective sheet of such embodiments may balance between P _L and P _H, it may be assumed to achieve both the peeling workability chemical penetration preventing property at high levels.

  The acrylic pressure-sensitive adhesive preferably contains a monomer unit derived from a carboxylic acid vinyl ester in a proportion higher than 20% by mass. By this, the protective sheet which can make chemical solution permeation prevention property and peeling workability compatible at a higher level can be realized. The monomer unit derived from the carboxylic acid vinyl ester may be contained in an acrylic polymer, may be contained in a polymer different from the acrylic polymer, or may be contained in both of them.

  In a preferred embodiment, the acrylic polymer that is the main component of the acrylic pressure-sensitive adhesive is synthesized by polymerizing (typically solution polymerization) a monomer material containing an alkyl (meth) acrylate and a carboxylic acid vinyl ester. It is. In other words, the acrylic polymer includes a monomer unit derived from an alkyl (meth) acrylate and a monomer unit derived from a carboxylic acid vinyl ester. The content of the carboxylic acid vinyl ester in the monomer raw material is preferably higher than 20% by mass. According to this aspect, a protective sheet that achieves both high-level prevention of chemical solution intrusion and peeling workability can be realized.

  The pressure-sensitive adhesive layer in the technique disclosed herein is preferably formed from a pressure-sensitive adhesive composition containing the acrylic polymer and an isocyanate-based crosslinking agent. A protective sheet having such a pressure-sensitive adhesive layer can achieve a higher level of both chemical solution intrusion prevention and peeling workability.

It is sectional drawing which shows typically the example of 1 structure of the protective sheet for chemical | medical solution processes. It is sectional drawing which shows typically the other structural example of the protective sheet for chemical | medical solution processing.

  Hereinafter, preferred embodiments of the present invention will be described. Matters necessary for the implementation of the present invention other than matters specifically mentioned in the present specification can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field. The “sheet” in this specification includes a film whose thickness is relatively thinner than the sheet and a tape generally referred to as an adhesive tape.

<Overall configuration of protective sheet>
The protective sheet disclosed here includes a base material and an adhesive layer provided on at least one surface of the base material. The shape of the protective sheet may be a sheet shape, and may be, for example, a roll shape or a single plate shape with a separator.
A typical configuration example of such a protective sheet is schematically shown in FIG. This protective sheet 10 includes a sheet-like substrate (for example, a resin-made sheet-like substrate) 1 and an adhesive layer 2 provided on one surface (one surface) thereof. The protective sheet 10 has an effect on the surface of the pressure-sensitive adhesive layer 2 on the adherend (material to be treated) before being treated with a chemical solution. The part to be excluded (hereinafter also referred to as “non-processing target part”)). This protects the non-processed portion from the chemical solution. As shown in FIG. 2, the protective sheet 10 before use (that is, before application to an adherend) typically has a surface of the pressure-sensitive adhesive layer 2 (applied surface to the adherend. Hereinafter, also referred to as an adhesive surface). .) May be protected by a release liner 3 having at least a pressure-sensitive adhesive layer 2 side as a release surface. Alternatively, the other surface of the base material 1 (the back surface of the surface on which the pressure-sensitive adhesive layer 2 is provided) is a peeling surface, and the pressure-sensitive adhesive layer 2 is formed on the other surface by winding the protective sheet 10 in a roll shape. The form which contact | abutted and the surface (adhesion surface) was protected may be sufficient. The protective sheet may be a double-sided pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is provided on each surface of the substrate. In that case, the adhesive surface (adhesive surface) of each pressure-sensitive adhesive layer may be protected by a release liner having at least a pressure-sensitive adhesive layer side as a release surface, and both surfaces are release surfaces. The form wound by the roll shape via the peeling liner used may be sufficient.

  As a base material used for the protective sheet, a known film-like or sheet-like base material can be appropriately selected and used. The material of the substrate is not particularly limited. For example, a base material formed from a metal material (aluminum or the like), a base material formed from a resin material, a base material formed from a composite material thereof (for example, a plastic film having a metal vapor-deposited on one side) or the like can be used. .

Preferred examples of the substrate in the technology disclosed herein include polyolefins such as polyethylene (PE), polypropylene (PP), ethylene propylene rubber (EPR), ethylene-propylene-butene copolymer, ethylene-ethyl acrylate copolymer, etc. Resin; Polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate; Polyamide resin (PA); Polyimide resin (PI); Polyphenylene sulfide resin (PPS); Polycarbonate resin (PC); Polyurethane resin (PU); ethylene-vinyl acetate resin (EVA); fluororesin such as polytetrafluoroethylene (PTFE); base material (plastic film) made of a resin material such as acrylic resin; The base material which consists of a resin material which contains such 1 type of resin independently may be sufficient, and the base material (plastic film) which consists of a resin material with which 2 or more types were blended may be sufficient.
Here, the plastic film typically refers to a non-porous plastic film and is a concept distinguished from a woven fabric and a non-woven fabric. As the base material of the protective sheet disclosed herein, any of an unstretched plastic film and a stretched (uniaxially stretched or biaxially stretched) plastic film can be used.

Among these, as a preferable resin material from the viewpoint of having appropriate flexibility, a polyolefin resin (for example, one of polyolefin resins such as PP, PE, EPR, or a mixture of two or more of them is blended). Polyolefin resin) and polyester resin (for example, PET). Polyolefin resins and polyester resins have moderate flexibility. A protective sheet provided with such a base material made of a resin material is easy to follow the step even when there is a step on the surface of the adherend (ie, has high surface shape followability). Therefore, it is difficult to form a chemical solution intrusion path (void) between the protective sheet adhesive and the adherend. Therefore, it is suitable as a base material for a protective sheet for chemical treatment.
In addition, the said level | step difference may originate in the structure formed in the surface of the to-be-adhered body. As an adherend having such a structure, for example, a transparent conductive film (for example, ITO (indium tin oxide) is partially formed on the surface, such as used in tablet computers, mobile phones, and organic LEDs (light emitting diodes). ) Film) or a glass substrate provided with FPC.

  As the base material of the protective sheet disclosed herein, one made of a resin material having high acid resistance can be preferably adopted. Such a base material is an acidic chemical solution (for example, a hydrofluoric acid solution used for glass etching, an acidic solution such as a chromium plating solution, a copper sulfate plating solution, a nickel plating solution, an acidic electroless nickel plating solution, or an acidic tin plating solution). Difficult to swell even when exposed to plating solution. This is advantageous in preventing an event that the acidic chemical solution swells the base material and enters the protective sheet to cause the chemical solution to reach the adherend (non-treatment target portion). As a preferable base material from the viewpoint of excellent balance between acid resistance and flexibility, a base material made of polyolefin resin is exemplified.

  The substrate may be a single layer or a multilayer structure having two or more layers (for example, a three-layer structure). For example, a resin film (multilayer film) having a multilayer structure including the above-described film can be used as the substrate. In the multilayer film, the resin material constituting each layer may be a resin material containing one kind of resin as described above alone, or may be a resin material in which two or more kinds of resins are blended.

  In a preferred embodiment, the substrate is a single-layer or multilayer polyolefin resin film. Here, the polyolefin resin film refers to a plastic film formed from a resin material containing a polyolefin resin (that is, a resin containing polyolefin as a main component). The proportion of the polyolefin resin in the resin component (polymer component) in the polyolefin resin film is preferably more than 50% by mass, preferably 75% by mass or more, and more preferably 90% by mass or more. The resin component may be a film substantially made of a polyolefin resin. Alternatively, a resin component is formed from a resin material containing a resin component (PA, PC, PU, EVA, etc.) other than a polyolefin resin in addition to a polyolefin resin as a main component (for example, a component exceeding 50% by mass in the resin component). It may be a film made.

  As the polyolefin resin, one kind of polyolefin can be used alone, or two or more kinds of polyolefins can be used in combination. The polyolefin may be, for example, a homopolymer of α-olefin, a copolymer of two or more α-olefins, a copolymer of one or two or more α-olefins and other vinyl monomers, and the like. Specific examples include ethylene-propylene copolymers such as PE, PP, EPR, ethylene-propylene-butene copolymers, ethylene-ethyl acrylate copolymers, and the like. Both low density (LD) polyolefins and high density (HD) polyolefins can be used. Such polyolefin resin films include biaxially oriented polypropylene (OPP) film, low density polyethylene (LDPE) film, linear low density polyethylene (LLDPE) film, medium density polyethylene (MDPE) film, and high density polyethylene (HDPE). ) Film, a polyethylene (PE) film obtained by blending two or more kinds of polyethylene (PE), a PP / PE blend film obtained by blending polypropylene (PP) and polyethylene (PE), and a polyolefin resin film such as various flexible polyolefin films. .

The PP may be various polymers (propylene-based polymers) containing propylene as a main monomer (main constituent monomer, that is, a component exceeding 50% by mass of the whole monomer). The concept of propylene-based polymer here includes, for example, the following polypropylene.
A homopolymer of propylene (ie homopolypropylene). For example, isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene.
A random copolymer (random polypropylene) of propylene and another α-olefin (typically, one or more selected from ethylene and an α-olefin having 4 to 10 carbon atoms). For example, random polypropylene obtained by random copolymerization of 96 to 99.9 mol% of propylene and 0.1 mol% to 4 mol% of another α-olefin (preferably ethylene and / or butene).
A copolymer (block polypropylene) obtained by block copolymerizing propylene with another α-olefin (typically, one or more selected from ethylene and an α-olefin having 4 to 10 carbon atoms). Such a block polypropylene may further contain a rubber component containing at least one of propylene and the other α-olefin as a by-product. For example, a polymer obtained by block copolymerization of 0.1 mol% to 10 mol% of other α-olefin (preferably ethylene and / or butene) with 90 mol% to 99.9 mol% of propylene, and propylene and other as by-products The block polypropylene which further contains the rubber component which uses as an ingredient at least 1 sort (s) among (alpha) -olefins.

  The polyolefin resin may be a resin (PP resin) in which the main component of the resin component is a propylene-based polymer as described above and another polymer is blended as a subcomponent. The other polymer includes an α-olefin other than propylene, for example, an α-olefin having 2 or 4 to 10 carbon atoms as a main monomer (a main constituent monomer, that is, a component exceeding 50% by mass of the whole monomer). One or more of the polyolefins to be treated. The PP resin may have a composition containing at least PE as the accessory component. The PE content can be, for example, 3 to 50 parts by mass (typically 5 to 30 parts by mass) per 100 parts by mass of PP. The resin component may be a PP resin substantially composed of PP and PE. Further, it may be a PP resin containing at least PE and EPR as subcomponents (for example, a PP resin whose resin component is substantially composed of PP, PE, and EPR). In this case, the content of EPR can be, for example, 3 to 50 parts by mass (typically 5 to 30 parts by mass) per 100 parts by mass of PP.

  The PE may be a homopolymer of ethylene or a copolymer of ethylene as a main monomer and another α-olefin (for example, an α-olefin having 3 to 10 carbon atoms). Preferable examples of the α-olefin include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. Any of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE) can be used. For example, LDPE and / or LLDPE can be preferably employed.

  A polyolefin resin film containing an olefin polymer alloy and a carbonyl unit-containing thermoplastic resin can also be used as the substrate. Here, the carbonyl unit-containing thermoplastic resin refers to a thermoplastic resin containing a carbonyl (C═O) unit in the molecular skeleton. Such a polyolefin resin film may be substantially free of halogen atoms and have flexibility, heat resistance, and flame retardancy comparable to polyvinyl chloride (PVC).

  The olefin polymer alloy is a component mainly for suppressing thermal deformation of the substrate, and is preferably a polymer alloy containing an ethylene component and a propylene component. The form of the polymer alloy is not particularly limited. For example, a polymer blend in which two or more kinds of polymers are physically mixed, a block copolymer or a graft copolymer in which two or more kinds of polymers are bonded by a covalent bond, and two kinds Various forms such as an IPN (Interpenetrating Polymer Network) structure in which the above polymers are intertwined without being covalently bonded to each other can be used. Further, it may be a compatible polymer alloy in which two or more kinds of polymers are compatible, or an incompatible polymer alloy in which two or more kinds of polymers are incompatible and form a phase separation structure.

  Examples of such an olefin polymer alloy include a polymer blend of polypropylene (homopolypropylene, random polypropylene) and polyethylene (including a copolymer of ethylene and a small amount of α-olefin), propylene / ethylene copolymer, propylene. A terpolymer of ethylene and other α-olefins other than these (as other α-olefins, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene) 1-octene, and 1-butene is preferred.

  When the olefin polymer alloy is a copolymer, it is preferably a multistage polymerized olefin copolymer (preferably an ethylene / propylene copolymer) polymerized by two or more stages of multistage polymerization. Examples of such a multistage polymerized olefin copolymer include polymer alloys as described in JP-A No. 2001-192629. That is, a first-stage polymerization is performed using a monomer mixture containing propylene as a main component, and then a polypropylene (first stage) / propylene-ethylene copolymer obtained by copolymerizing propylene and ethylene in the second and subsequent stages ( It is a polymer alloy of the second and subsequent stages. The first stage polymerization is preferably carried out in the presence of a titanium compound catalyst and an organoaluminum compound catalyst. The second and subsequent polymerizations are preferably carried out in the presence of a titanium-containing polyolefin formed by the first polymerization and an organoaluminum compound catalyst. As the titanium compound catalyst, for example, titanium trichloride and magnesium chloride were co-ground and treated with n-butyl orthotitanate, 2-ethyl-hexanol, ethyl p-toluate, silicon tetrachloride, diisobutyl phthalate, or the like. Examples thereof include a solid catalyst having a spherical shape and an average particle diameter of 1 to 30 μm. Examples of the organoaluminum compound catalyst include alkylaluminum such as triethylaluminum. In the polymerization layer, a silicon compound such as diphenyldimethoxysilane or an iodine compound such as ethyl iodide may be added as an electron donor.

  From the viewpoint of suppressing thermal deformation, the olefin-based polymer alloy has a dynamic storage elastic modulus (E ′) at 80 ° C. of 40 MPa or more and less than 180 MPa (for example, 45 MPa to 160 MPa) and dynamic storage at 120 ° C. Those having an elastic modulus (E ′) of 12 MPa or more and less than 70 MPa (for example, 15 MPa to 65 MPa) are preferable. In consideration of surface shape followability and workability near room temperature, the dynamic storage elastic modulus (E ′) at 23 ° C. is preferably 200 MPa or more and less than 400 MPa. The dynamic storage elastic modulus (E ′) is obtained by preparing a test piece (thickness 0.2 mm, width 10 mm, length 20 mm) by polymer alloy, and measuring dynamic viscoelastic behavior due to temperature dispersion of the test piece. It is a value measured using DMS200 (manufactured by Seiko Instruments Inc.) as a device under predetermined measurement conditions (for example, measurement method: tension mode, temperature increase rate: 2 ° C./min, frequency: 1 Hz). As an example of such a polymer alloy, trade names “Cataloy KS-353P”, “Cataloy KS-021P”, “Cataloy C200F”, “Cataloy Q-200F” manufactured by Sun Allomer Co., Ltd., and the like can be given.

  The said carbonyl unit containing thermoplastic resin is used in order to give a moderate softness | flexibility and favorable extendibility to a base material, and is a thermoplastic resin which contains a carbonyl (C = O) unit in molecular skeleton. As will be described later, when the polyolefin resin film contains an inorganic flame retardant, it may be a component that activates the flame retardancy imparting action of the inorganic flame retardant. As such a thermoplastic resin, a flexible polyolefin resin containing a carbonyl unit in the molecular skeleton is suitable. For example, an ethylene copolymer (ethylene / vinyl ester copolymer, ethylene / unsaturated carboxylic acid copolymer) synthesized using a vinyl ester and / or an α, β-unsaturated carboxylic acid or a derivative thereof as a monomer or comonomer. And the like, and metal salts thereof. The melting point of the thermoplastic resin is not particularly limited, but is preferably 120 ° C. or lower (typically 40 to 100 ° C.). The melting point can be measured by a general differential scanning calorimeter (DSC).

  Examples of the vinyl ester in the ethylene copolymer or the metal salt thereof include carboxylic acid vinyl esters such as vinyl acetate. Examples of the α, β-unsaturated carboxylic acid or derivatives thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, maleic anhydride, and itaconic anhydride or anhydrides thereof; methyl ( (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, cyclohexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, maleic acid Examples thereof include unsaturated carboxylic acid esters such as 1-methyl, 1-ethyl maleate, diethyl maleate, 1-methyl fumarate, and glycidyl (meth) acrylate. These can be used alone or in combination of two or more. Of these, alkyl (meth) acrylate is preferable, and ethyl acrylate is more preferable.

  Preferable examples of ethylene / vinyl ester copolymer and ethylene / unsaturated carboxylic acid copolymer include ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / ethyl acrylate copolymer, ethylene / acrylic. Acid / ethyl acrylate copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl acetate / ethyl acrylate copolymer, ethylene / glycidyl methacrylate copolymer, ethylene / glycidyl methacrylate-ethyl acrylate copolymer, and metal salts thereof Is mentioned. These can be used alone or in combination of two or more.

  The polyolefin resin film containing the olefin polymer alloy and the carbonyl unit-containing thermoplastic resin preferably contains an inorganic flame retardant. Examples of such inorganic flame retardants include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, calcium hydroxide, and barium hydroxide; basic magnesium carbonate, magnesium carbonate-calcium, calcium carbonate, Metal carbonates such as barium carbonate and dolomite; metal hydrates such as hydrotalcite and borax (hydrates of metal compounds); inorganic metal compounds such as barium metaborate and magnesium oxide. These can be used alone or in combination of two or more. Of these, metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, calcium hydroxide, and barium hydroxide, basic magnesium carbonate, and hydrotalcite are preferable.

  The inorganic flame retardant is also preferably subjected to a surface treatment with a silane coupling agent. Thereby, various properties such as flexibility, heat resistance and flame retardancy can be further improved. Specific examples of such silane coupling agents include vinyltriethoxysilane, vinyl-tolyl (2-methoxy-ethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ- Aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxy Examples include silane, N-phenyl-γ-aminopropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane. These can be used alone or in combination of two or more.

  The method for surface treatment of the inorganic metal compound with the silane coupling agent is not particularly limited, and conventionally known methods such as a dry treatment method and a wet treatment method can be appropriately employed. The amount of adhesion of the silane coupling agent to the surface of the inorganic metal compound can vary depending on the type of coupling agent, the type of inorganic metal compound, the specific surface area, etc. Usually, it is about 0.1 mass part-5.0 mass parts (for example, 0.3 mass part-3.0 mass parts).

  The blending ratio of the olefin polymer alloy and the carbonyl unit-containing thermoplastic resin is not particularly limited, but is preferably 90:10 to 20:80 on a mass basis, for example, from the viewpoint of achieving both heat resistance and flame retardancy. Moreover, when mix | blending an inorganic type flame retardant, the compounding quantity is a polymer component (for example, the above-mentioned multistage polymerization olefin copolymer and a carbonyl unit containing thermoplastic resin from a viewpoint of a flame retardance improvement and a softness | flexibility maintenance. The total is preferably about 10 to 200 parts by mass (for example, 20 to 100 parts by mass) with respect to 100 parts by mass.

  Any resin film described above may contain an appropriate component depending on the use of the protective sheet, if necessary. For example, additives such as light stabilizers such as radical scavengers and ultraviolet absorbers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slip agents, antiblocking agents, etc. may be appropriately blended. it can. Examples of light stabilizers include those containing benzotriazoles, hindered amines, benzoates and the like as active ingredients. Examples of the antioxidant include those containing alkylphenols, alkylene bisphenols, thiopropylene acid esters, organic phosphite esters, amines, hydroquinones, hydroxylamines and the like as active ingredients. Each of these additives can be used alone or in combination of two or more. The amount of the additive should be the same as the usual amount of the resin film used as the base material of the protective sheet in the application depending on the use of the protective sheet (for example, for glass etching and plating masking). Can do.

  Such a substrate (resin film) can be produced by appropriately adopting a conventionally known general film forming method (extrusion molding, inflation molding, etc.). The surface of the substrate on which the pressure-sensitive adhesive layer is provided (the surface on the pressure-sensitive adhesive layer side, the surface to which the pressure-sensitive adhesive is applied) is treated to improve the adhesiveness with the pressure-sensitive adhesive layer (throwing of the pressure-sensitive adhesive) Surface treatment such as corona discharge treatment, acid treatment, ultraviolet irradiation treatment, plasma treatment, and primer (primer) coating may be performed. As the surface treatment (primer treatment) by primer application, it is preferable to use an undercoat agent in which an isocyanate is blended with an acrylic polymer. The surface (back surface) opposite to the pressure-sensitive adhesive layer side surface of the base material may be subjected to surface treatment such as antistatic treatment or peeling treatment, if necessary. As the release treatment, for example, by providing a long-chain alkyl-based or silicone-based release treatment layer on the back surface of the base material, the unwinding force of the protective sheet wound in a roll shape can be reduced.

  The thickness of a base material can be suitably selected according to the flexibility (hardness) etc. of the resin film to be used. In general, the thickness of the base material is 500 μm or less (preferably 300 μm or less, more preferably 200 μm or less, typically 100 μm or less, for example, 80 μm or less) from the viewpoint of followability and adhesion to a stepped surface. It is. Further, from the viewpoint of peeling workability and other handling properties (handling properties), the thickness of the substrate is suitably 10 μm or more (preferably 20 μm or more, more preferably 25 μm or more, for example, 30 μm or more). Moreover, when the thickness of a base material becomes large, it exists in the tendency which becomes easy to prevent the swelling penetration | invasion of the chemical | medical solution from the protective sheet surface.

  The kind of adhesive which comprises the adhesive layer provided on the said base material is not specifically limited. For example, acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives (natural rubber-based, synthetic rubber-based, mixed systems thereof, etc.), silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, polyether-based pressure-sensitive adhesives, fluorine-based pressure-sensitive adhesives, etc. 1 type or 2 types or more of adhesives selected from these various adhesives. Of these, acrylic adhesives, rubber adhesives, and silicone adhesives are preferred because they are excellent in resistance to chemicals (for example, acidic chemicals such as etching solutions and acidic plating solutions). Similarly, the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive is not particularly limited, and a composition in which the polymer constituting the pressure-sensitive adhesive described above is blended and the blending ratio is appropriately selected can be used.

  Especially, it is preferable that the adhesive which comprises an adhesive layer is an acrylic adhesive containing an acrylic polymer as a base polymer (The main component in a polymer component, main adhesive component). Here, the “base polymer” refers to a main component (main adhesive component) among the polymer components contained in the adhesive, and typically refers to a component occupying more than 50% by mass of the polymer component. The “acrylic polymer” refers to a polymer including a monomer unit derived from a monomer (acrylic monomer) having at least one (meth) acryloyl group in one molecule. The acrylic polymer includes an acrylic monomer, and a monomer raw material (a single monomer or a monomer that may further include another monomer copolymerizable with the acrylic monomer (that is, a monomer having no (meth) acryloyl group)) It may be a polymer (copolymer) synthesized by polymerizing a monomer mixture.

A typical example of the acrylic polymer is one in which the main component of the acrylic monomer contained in the monomer raw material is an alkyl (meth) acrylate. “(Meth) acrylate” means acrylate and methacrylate comprehensively. Similarly, “(meth) acryloyl” refers to acryloyl and methacryloyl, and “(meth) acryl” refers to acryl and methacryl generically.
The proportion of the alkyl (meth) acrylate in the acrylic monomer contained in the monomer raw material typically exceeds 50% by mass, preferably 60% by mass or more, more preferably 70% by mass or more. For example, 80 mass. In a preferred embodiment, the proportion of alkyl (meth) acrylate in the acrylic monomer may be 90% by mass. A monomer raw material having a composition containing only alkyl (meth) acrylate as the acrylic monomer may be used. Alternatively, the monomer raw material may contain an acrylic monomer other than alkyl (meth) acrylate, for example, for the purpose of adjusting the adhesion performance or gel fraction. In that case, the ratio of the alkyl (meth) acrylate to the acrylic monomer in the monomer raw material can be, for example, 99.5% by mass or less, and may be 99% by mass or less (for example, 98% by mass or less). .

As the alkyl (meth) acrylate, for example, a compound represented by the following formula (1) can be preferably used.
CH ₂ = CR ¹ COOR ² (1)
Here, R ¹ in the above formula (1) is a hydrogen atom or a methyl group. R ² is a linear or branched alkyl group, typically a C _1-20 alkyl group. From the viewpoint of the storage elastic modulus of the pressure-sensitive adhesive, an alkyl (meth) acrylate in which R ² is a C _1-14 (eg, C _1-10 ) alkyl group can be preferably used.
In this specification, C _ab refers to a range of the number of carbon atoms (a or more and b or less). For example, a C _1-20 alkyl group refers to an alkyl group having 1 to 20 carbon atoms.

Examples of the alkyl (meth) acrylate in which R ² is a C _1-20 alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) ) Acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2 -Ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate Rate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, Nonadecyl (meth) acrylate, eicosyl (meth) acrylate, etc. are mentioned. These can be used alone or in combination of two or more.

Among them, the alkyl ^{R 2} is an alkyl group of _{C 4-10} (meth) acrylate, for example, n- butyl acrylate, n- butyl methacrylate, 2-ethylhexyl acrylate. For example, the ratio of one or more of these is 30% by mass or more in total (preferably 40% by mass to 99% by mass, for example, 50% by mass to 98% by mass, typically exceeding 50% by mass. (A proportion of 97% by mass or less). In the acrylic polymer, one or more of alkyl (meth) acrylates in which R ² is a C _4-10 alkyl group is 40% by mass to 90% by mass in total (more preferably 50% by mass to 80% by mass). The copolymer may be copolymerized at a ratio of not more than mass%, typically exceeding 50 mass% and not more than 70 mass%, for example exceeding 50 mass% and not more than 60 mass%.

In a preferred embodiment of the technology disclosed herein, a monomer in which R ² in the above formula (1) is an alkyl group having 6 or more carbon atoms (for example, 7 or more, typically 8) can be used. Since such a monomer has a relatively large number of carbon atoms in the alkyl group, it has a high hydrophobicity, and this can be expected to prevent the penetration of a chemical solution (particularly, a chemical solution containing an aqueous solvent). In consideration of easy availability of raw materials, ease of production, polymerization reactivity, prevention of chemical penetration, and the like, the number of carbon atoms is preferably about 20 or less. For example, alkyl (meth) acrylates in which R ² is a hexyl group, heptyl group, octyl group, nonyl group, 2-ethylhexyl group, propylhexyl group or the like are preferable. Among these, a preferable monomer includes alkyl (meth) acrylate in which R ² is a 2-ethylhexyl group. These monomers can be used individually by 1 type or in combination of 2 or more types.

In such an embodiment, that is, when a monomer in which R ² in the formula (1) is an alkyl group having 6 or more carbon atoms (for example, 7 or more, typically 8) is used, the monomer raw material has a glass transition temperature ( In order to adjust Tg) and improve cohesion, R ² in the above formula (1) may further contain an alkyl (meth) acrylate which is a C _1-5 alkyl group. Examples of such alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and s-butyl. Examples include (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, and isopentyl (meth) acrylate. These can be used alone or in combination of two or more.

In the alkyl (meth) acrylate represented by the above formula (1), the proportion of the monomer in which R ² is an alkyl group having 6 or more carbon atoms can be, for example, a proportion exceeding 50% by mass, preferably It is 60 mass% or more, More preferably, it is 70 mass% or more. From the viewpoint of improving the hydrophobicity of the resulting pressure-sensitive adhesive and improving the chemical solution intrusion prevention property (typically, the performance of preventing the chemical solution from entering due mainly to swelling of the pressure-sensitive adhesive with an aqueous chemical solution). May be 80 mass% or more (for example, 90 mass% or more, typically 95 mass% or more). As the alkyl (meth) acrylate, only a monomer in which R ² is an alkyl group having 6 or more carbon atoms may be used. Therefore, in the alkyl (meth) acrylate represented by the above formula (1), the proportion of the alkyl (meth) acrylate having an alkyl group having 1 to 5 carbon atoms is 20% by mass or less (for example, 10% by mass or less, Typically, it is preferably 5% by mass or less. Or the composition which does not use the alkyl (meth) acrylate whose R _< ² _> is a _C1-5 alkyl group may be sufficient.

  The monomer raw material used for synthesizing the acrylic polymer is a compound other than alkyl (meth) acrylate in addition to alkyl (meth) acrylate (hereinafter also referred to as monomer A), and alkyl (meth) acrylate and A copolymerizable comonomer (hereinafter also referred to as monomer B) may be included. Such a comonomer can be used for the purpose of improving various properties such as adhesion, non-contamination (adhesive residue prevention), light release property, and heat resistance. The monomer B is not limited to the monomer, and may be an oligomer copolymerizable with the monomer A.

Examples of the monomer B include a monomer having a functional group (hereinafter also referred to as a functional group-containing monomer). Such a functional group-containing monomer can be added for the purpose of introducing a crosslinking point into the acrylic polymer and increasing the cohesive strength of the acrylic polymer. As such a functional group-containing monomer,
For example, ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, ethylenically unsaturated such as itaconic acid, maleic acid, fumaric acid, citraconic acid Carboxyl group-containing monomers such as dicarboxylic acids;
For example, an acid anhydride group-containing monomer such as an acid anhydride such as the above-mentioned ethylenically unsaturated dicarboxylic acid such as maleic anhydride or itaconic anhydride;
For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl Hydroxyalkyl (meta) such as (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl (meth) acrylate ) Acrylates, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol Call hydroxyl group and unsaturated alcohols such as monovinyl ether (hydroxyl group) containing monomer;
Functional group-containing monomers containing a nitrogen atom in the functional group, such as amide group-containing monomers, amino group-containing monomers, and cyano group-containing monomers described below, that is,
For example, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, Amide group-containing monomers such as N-butoxymethyl (meth) acrylamide;
For example, amino group-containing monomers such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate;
For example, cyano group-containing monomers such as acrylonitrile and methacrylonitrile;
For example, sulfonic acids such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid Group-containing monomers;
For example, a phosphate group-containing monomer such as 2-hydroxyethylacryloyl phosphate;
For example, epoxy group (glycidyl group) -containing monomers such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether;
For example, keto group-containing monomers such as diacetone (meth) acrylamide, diacetone (meth) acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetoacetate, vinyl acetoacetate;
For example, an isocyanate group-containing monomer such as 2- (meth) acryloyloxyethyl isocyanate;
For example, alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate;
For example, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxypropylmethyldiethoxysilane, etc. An alkoxysilyl group-containing monomer of
Is mentioned. These can be used alone or in combination of two or more. Among them, a functional group-containing monomer such as a carboxyl group, a hydroxyl group, and an epoxy group is preferable because a crosslinking point can be suitably introduced into the acrylic polymer and the cohesive force of the acrylic polymer can be further increased. . A carboxyl group-containing monomer or a hydroxyl group-containing monomer is more preferable. Carboxyl group-containing monomers are particularly preferred.

The monomer raw material in the technique disclosed herein may contain a monomer other than the functional group-containing monomer as the monomer B for the purpose of adjusting the Tg of the acrylic polymer and improving the cohesive force. Such monomers include
For example, vinyl acetates such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl cyclohexanecarboxylate, vinyl benzoate and the like;
For example, aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), vinyl toluene, etc .;
Aromatics such as aryl (meth) acrylate (eg phenyl (meth) acrylate), aryloxyalkyl (meth) acrylate (eg phenoxyethyl (meth) acrylate), arylalkyl (meth) acrylate (eg benzyl (meth) acrylate) Sex ring-containing (meth) acrylates;
For example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N A monomer having a nitrogen atom-containing ring such as vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N- (meth) acryloylmorpholine;
For example, olefinic monomers such as ethylene, propylene, isoprene, butadiene, isobutylene;
For example, chlorine-containing monomers such as vinyl chloride and vinylidene chloride;
For example, vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether;
Examples thereof include cycloalkyl (meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate. These can be used alone or in combination of two or more.

  The monomer raw material may also contain a comonomer such as a multifunctional monomer as the monomer B for the purpose of crosslinking or the like, if necessary. Examples of such polyfunctional monomers include hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and polypropylene glycol di (meth) acrylate. , Neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like. These can be used alone or in combination of two or more.

The total amount of such acrylic monomers (monomers having at least one (meth) acryloyl group in one molecule) can be, for example, 30% by mass or more of all monomer raw materials constituting the acrylic polymer. From the viewpoint of adhesion to the adherend and the like, usually, the total amount of acrylic monomers is preferably 40% by mass or more of all monomer raw materials constituting the acrylic polymer, and is 50% by mass or more (for example, more than 50% by mass). ) Is more preferable. In one embodiment, the total amount of acrylic monomers is 70% by mass or more (preferably 80% by mass or more, more preferably 90% by mass or more, for example, 95% by mass or more, further 99% by mass of all monomer raw materials constituting the acrylic polymer. (Mass% or more) may be sufficient and the monomer raw material which consists only of acrylic monomers may be sufficient.
The acrylic polymer may be a copolymer of an acrylic monomer and a monomer other than the acrylic monomer. In this case, the copolymerization ratio of the monomer other than the acrylic monomer can be, for example, 1 to 70% by mass, usually 1 to 60% by mass is preferable, 5 to 50% by mass is preferable, and 10 to 50%. The mass% is more preferable. In a preferred embodiment, the copolymerization ratio of monomers other than the acrylic monomer may be 20 to 50% by mass (for example, 30% by mass or more and less than 50% by mass).

When using the functional group-containing monomer as described above as the monomer constituting the acrylic polymer, from the viewpoint of achieving both high adhesion and peeling workability, alkyl (meth) acrylate (preferably in the above formula (1) Functional group-containing monomer (preferably carboxyl group-containing monomer) is 1 part by mass to 10 parts by mass (for example, 2 parts by mass to 100 parts by mass of alkyl (meth) acrylate) in which R ² is a C _4-10 alkyl group. 8 parts by mass, typically 3 parts by mass to 7 parts by mass). For example, by using an appropriate amount of a carboxyl group-containing monomer, adhesion to an adherend (particularly, an adherend having a surface made of glass or other polar material) is improved, and from the interface between the pressure-sensitive adhesive and the adherend. It is possible to better prevent the chemical solution from entering.
When a monomer other than the above functional group-containing monomer is used as the monomer constituting the acrylic polymer, an alkyl (meth) acrylate (preferably in the above formula (1) is used from the viewpoint of achieving both high adhesion and peeling workability. 1 part by mass of a monomer other than the above functional group-containing monomer (preferably a carboxylic acid vinyl ester such as vinyl acetate) with respect to 100 parts by mass of R ² is an alkyl (meth) acrylate having a C _4-10 alkyl group. It is preferable to include 100 parts by mass (for example, 2 parts by mass to 90 parts by mass, typically 5 parts by mass to 85 parts by mass).
When using the above-mentioned polyfunctional monomer as a monomer constituting the acrylic polymer, alkyl (meth) acrylate (preferably R ² in the above formula (1) is used from the viewpoint of achieving both high adhesion and peeling workability. 30 parts by mass or less (for example, 20 parts by mass or less, typically 1 part by mass to 10 parts by mass) with respect to 100 parts by mass of alkyl (meth) acrylate in which is a C _4-10 alkyl group. Part) is preferably included.

In a preferred embodiment of the technology disclosed herein, the acrylic polymer may include an alkyl (meth) acrylate and a carboxylic acid vinyl ester in its monomer composition. Such an acrylic polymer is typically obtained by polymerizing (typically solution polymerization) a monomer material containing an alkyl (meth) acrylate and a carboxylic acid vinyl ester. The use of the carboxylic acid vinyl ester can contribute to prevention of chemical solution intrusion from the interface between the pressure-sensitive adhesive and the adherend through improvement in adhesion to the adherend (for example, a glass substrate).
Examples of the vinyl carboxylate include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl cyclohexanecarboxylate, vinyl benzoate and the like. These can be used alone or in combination of two or more. Among these, from the viewpoint of improving the low-speed peel strength, the glass transition temperature (Tg) of homopolymers such as vinyl acetate, vinyl propionate and vinyl butyrate is higher than −20 ° C. (for example, higher than −20 ° C. and 80 ° C. The following carboxylic acid vinyl esters are preferred. Particularly preferred carboxylic acid vinyl ester is vinyl acetate.
The content ratio of the carboxylic acid vinyl ester in the monomer raw material (when two or more carboxylic acid vinyl esters are included, the total ratio thereof) can be, for example, 1 to 60% by mass, and preferably 5 to 50% by mass. 10 to 50% by mass is more preferable. In a preferred embodiment, the content of the carboxylic acid vinyl ester may be 20 to 50% by mass (for example, 30% by mass or more and less than 50% by mass).

  The technique disclosed here can be preferably implemented in an embodiment in which the monomer raw material constituting the acrylic polymer has a composition containing only an alkyl (meth) acrylate and a carboxyl group-containing monomer as the acrylic monomer. As a preferred example of such an embodiment, there is an embodiment in which only an alkyl (meth) acrylate and a carboxyl group-containing monomer are included as an acrylic monomer, and a carboxylic acid vinyl ester (for example, vinyl acetate) is included as a monomer other than the acrylic monomer. In this case, it is preferable to include 15 to 100 parts by mass (for example, 30 to 95 parts by mass, typically 50 to 90 parts by mass) of the carboxylic acid vinyl ester with respect to 100 parts by mass of the alkyl (meth) acrylate.

  Although it does not specifically limit, It is preferable that the copolymer composition of an acrylic polymer is set so that Tg of this acrylic polymer may be in the range of -70 degreeC--20 degreeC. From the standpoint of achieving both a high level of chemical solution penetration prevention and peeling workability, the acrylic polymer has a Tg of -60 ° C to -20 ° C (more preferably -50 ° C to -20 ° C, such as -40 ° C to -20 ° C. It is more preferable that the temperature is set to (° C.). When the Tg of the acrylic polymer is not too high, good adhesion to the surface of the adherend is exhibited, and the penetration of the chemical solution from the interface between the pressure-sensitive adhesive and the adherend can be effectively prevented. Further, the Tg of the acrylic polymer not being too low can also contribute to prevention of chemical solution intrusion (typically, chemical solution infiltration mainly due to swelling of the adhesive with the chemical solution).

  Here, the Tg of the acrylic polymer is a fox based on the Tg of a homopolymer of each monomer constituting the polymer and the mass fraction (copolymerization ratio based on mass) of the monomer. The value obtained from the formula. Accordingly, the Tg of the acrylic polymer can be adjusted by appropriately changing the composition of the monomer raw material (that is, the type of monomer used and the ratio of the amount used). As the Tg of the homopolymer, the value described in known materials is adopted.

In the technique disclosed here, the following values are specifically used as the Tg of the homopolymer.
2-Ethylhexyl acrylate -70 ° C
n-Butyl acrylate -55 ° C
Ethyl acrylate -22 ° C
Methyl acrylate 8 ℃
Methyl methacrylate 105 ° C
Cyclohexyl methacrylate 66 ° C
Vinyl acetate 32 ° C
2-hydroxyethyl acrylate -15 ° C
Styrene 100 ° C
Vinyl chloride 82 ℃
Acrylic acid 106 ℃
Methacrylic acid 130 ° C
For the Tg of homopolymers other than those exemplified above, the values described in “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc, 1989) shall be used.

When not described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc, 1989), values obtained by the following measurement method are used (Japanese Patent Laid-Open No. 2007-51271). reference).
Specifically, in a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, 100 parts by mass of monomer, 0.2 parts by mass of azobisisobutyronitrile and 200 parts by mass of ethyl acetate as a polymerization solvent were added. Stir for 1 hour while flowing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature is raised to 63 ° C. and the reaction is carried out for 10 hours. Next, the mixture is cooled to room temperature to obtain a homopolymer solution having a solid concentration of 33% by weight. Next, this homopolymer solution is cast-coated on a release liner and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. This test sample was punched into a disk shape having a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to shear strain at a frequency of 1 Hz using a viscoelasticity tester (ARES, manufactured by Rheometrics), in a temperature range of −70 to 150 ° C. The viscoelasticity is measured by the shear mode at a heating rate of 5 ° C./min, and the peak top temperature of tan δ is defined as Tg of the homopolymer.

  A method for polymerizing the monomer or a mixture thereof (monomer raw material) is not particularly limited, and a conventionally known general polymerization method can be employed. Examples of such a polymerization method include solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. Among these, solution polymerization is preferable because it is excellent in water resistance and chemical solution penetration prevention. The mode of polymerization is not particularly limited, and can be performed by appropriately selecting conventionally known monomer supply methods, polymerization conditions (temperature, time, pressure, etc.) and use components other than the monomers (polymerization initiator, polymerization solvent, etc.). . For example, as a monomer supply method, the entire monomer mixture may be supplied to the reaction vessel at one time (collective supply), or may be gradually dropped and supplied (continuous supply), or divided into several times to be predetermined. Each amount may be supplied (divided supply) every time. The monomer or a mixture thereof may be partially or entirely supplied as a solution dissolved in a solvent or a dispersion emulsified in water.

  When emulsion polymerization is employed as the method for polymerizing the acrylic polymer, a general emulsion polymerization emulsifier can be appropriately selected and used as the emulsifier (surfactant). Usually, it is preferable to use an anionic emulsifier or a nonionic emulsifier (which may be a radical polymerizable emulsifier (reactive emulsifier) having a radical polymerizable functional group). Such emulsifiers can be used singly or in combination of two or more. The amount of the emulsifier used (solid content basis) is, for example, about 0.2 to 10 parts by mass (preferably about 0.5 to 5 parts by mass) with respect to 100 parts by mass of the monomer raw material. it can.

  When solution polymerization is employed as the polymerization method for the acrylic polymer, examples of the polymerization solvent include aromatic compounds such as toluene and xylene (typically aromatic hydrocarbons); acetates such as ethyl acetate and butyl acetate. Any one selected from aliphatic or alicyclic hydrocarbons such as hexane, cyclohexane and methylcyclohexane; halogenated alkanes such as 1,2-dichloroethane; ketones such as methyl ethyl ketone and acetylacetone; A solvent or 2 or more types of mixed solvents can be used.

  Although it does not specifically limit as a polymerization initiator, For example, the redox type | system | group which combined oxidizing agents and reducing agents, such as an azo initiator, a peroxide initiator, a substituted ethane initiator, and a peroxide. An initiator etc. are illustrated. As the azo initiator, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate, 2,2 '-Azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile (AMBN), 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2' -Azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (N, N'-dimethyleneisobutylamidine) dihydrochloride is exemplified. Examples of the peroxide initiator include persulfates such as potassium persulfate and ammonium persulfate; benzoyl peroxide (BPO), t-butyl hydroperoxide, and hydrogen peroxide. Examples of substituted ethane initiators include phenyl substituted ethane. Examples of the redox initiator include a combination of persulfate and sodium bisulfite, and a combination of peroxide and sodium ascorbate. Of these, azo initiators are preferred from the viewpoint of chemical solution penetration prevention.

  Although the usage-amount of a polymerization initiator can be suitably selected according to the kind of polymerization initiator, the kind of monomer (composition of a monomer mixture), etc., it is 0.005-mass part normally with respect to 100 mass parts of monomer raw materials normally. It is appropriate to select from a range of about 1 part by mass. As a method for supplying the polymerization initiator, any of a batch charging method, a continuous supply method, a divided supply method, etc. in which substantially the entire amount of the polymerization initiator to be used is put in the reaction vessel before the supply of the monomer mixture is started. It is. From the viewpoint of ease of polymerization operation, ease of process control, etc., for example, a batch charging method can be preferably employed. The polymerization temperature can be, for example, about 20 ° C. to 100 ° C. (typically 40 ° C. to 90 ° C.).

  For the above polymerization, various conventionally known chain transfer agents (which may be grasped as molecular weight regulators or polymerization degree regulators) can be used as necessary. Such chain transfer agents are selected from mercaptans such as dodecyl mercaptan (dodecanethiol), glycidyl mercaptan, 2-mercaptoethanol, mercaptoacetic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, and the like. There may be one or more. When the chain transfer agent is used, the amount used is not particularly limited, but can be, for example, about 0.001 to 0.5 parts by mass with respect to 100 parts by mass of the monomer raw material. Alternatively, a chain transfer agent need not be used. As a preferred embodiment, an embodiment in which the monomer raw material is polymerized by solution polymerization without using a chain transfer agent can be mentioned.

The weight average molecular weight of the acrylic polymer is not particularly limited, but usually about 30 × 10 ^{4 to} 150 × 10 ⁴ is appropriate. When solution polymerization is used as the polymerization method, the weight average molecular weight of the acrylic polymer is suitably about 30 × 10 ⁴ to 70 × 10 ⁴ from the viewpoint of solution viscosity, adhesive performance, etc., and 40 × 10 ^{4 to} 60 About × 10 ⁴ is preferable.

  The pressure-sensitive adhesive layer of the protective sheet disclosed herein may be formed using a pressure-sensitive adhesive composition containing an acrylic polymer as described above. For example, the pressure-sensitive adhesive composition may be prepared by subjecting a polymerization reaction liquid obtained by polymerizing a monomer raw material (typically solution polymerization) to an appropriate treatment such as concentration adjustment or pH adjustment as necessary, or acrylic. It can be prepared by appropriately blending a pressure-sensitive adhesive forming component (polymer, tackifier, etc.), an additive (for example, a crosslinking agent) and the like other than the polymer.

  The form of the pressure-sensitive adhesive composition is not particularly limited. For example, various forms such as a solvent type, an aqueous emulsion type, an aqueous solution type, an active energy ray (for example, ultraviolet ray) curable type, and a hot melt type may be used. Among these, a solvent-type pressure-sensitive adhesive composition is particularly preferable from the viewpoint of resistance to an aqueous chemical solution (prevention of chemical solution penetration). Such a solvent-type pressure-sensitive adhesive composition is typically prepared in the form of a solution containing the acrylic polymer in an organic solvent. As said organic solvent, the thing similar to the polymerization solvent used for solution polymerization can be used. Although not particularly limited, from the viewpoints of drying efficiency and coating properties of the pressure-sensitive adhesive composition, the solvent-type pressure-sensitive adhesive composition is usually contained in a solid content (NV) of 10 to 55% by mass (for example, 15 to 45). It is appropriate to prepare it at (mass%).

The pressure-sensitive adhesive composition (typically a solvent-type pressure-sensitive adhesive composition) in the technology disclosed herein preferably contains a release adjusting agent in addition to the acrylic polymer. The release modifier, it is possible to use various materials (in other _words, the value of _P L / P _H) balance between low-speed peeling strength P _L and the high-speed peel strength P _H may regulate. In particular, use of a release modifier that may increase the value of P _{L /} P _H by significantly reducing the high speed peel strength than the low-speed peel strength are preferred.

The technique disclosed herein can be preferably implemented in an embodiment that includes a compound having a hydrophilic part and a lipophilic part in one molecule as the above-described release modifier. As such a release adjusting agent, a known anionic surfactant, nonionic surfactant, cationic surfactant or the like can be used. Of these, anionic surfactants or nonionic surfactants are preferred.
Examples of the anionic surfactant include alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate; alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate; (poly) oxyethylene lauryl amine, (poly) oxyethylene stearyl amine, and the like. (Poly) etheramine; (poly) ether sulfate such as sodium (poly) oxyethylene alkyl ether sulfate, ammonium (poly) oxyethylene alkylphenyl ether sulfate, sodium (poly) oxyethylene alkylphenyl ether sulfate; (poly) oxyethylene Examples include sodium alkylsulfosuccinate and (poly) oxyethylene alkyl ether phosphate.
Examples of the nonionic surfactant include (poly) oxyethylene alkyl ether, (poly) oxyethylene alkylphenyl ether, (poly) oxyethylene fatty acid ester, polyoxyethylene polyoxypropylene block polymer, and the like.
Here, the term “(poly) oxyethylene” means that both the number of repeating oxyethylene units (number of added moles of ethylene oxide) is 1 and the number is 2 or more. The same applies to (poly) ether.

In a preferred aspect of the technology disclosed herein, the release modifier has at least one of a -POH group, a -COH group, and a -SOH group. Especially, the peeling regulator which has -POH group is preferable. Such release modifiers typically contain a phosphate ester structure, such as monoesters of phosphoric acid (ROP (= O) (OH) ₂ ; where R is a monovalent organic group), diesters ((RO) ₂ P (═O) OH; where R is the same or different monovalent organic group), a mixture containing both a monoester and a diester, and the like.

Examples of the release adjusting agent having a -POH group include phosphoric acid alkyl ester and (poly) oxyethylene alkyl ether phosphoric acid ester. The (poly) oxyethylene alkyl ether phosphate ester as the release adjusting agent may be a monoester of phosphoric acid, a diester, or a mixture containing both the monoester and the diester.
The average number of repeating oxyethylene units in the (poly) oxyethylene alkyl ether phosphate ester may be, for example, about 1 to 10. In consideration of the balance between the ability to reduce the high-speed peel strength and the prevention of chemical penetration, (poly) oxyethylene alkyl ether phosphates having an average number of repetitions of 1 to 6 (for example, 2 to 4) are preferably employed. obtain.
Moreover, the alkyl group in (poly) oxyethylene alkyl ether phosphate ester may be a C6-C20 alkyl group, for example. In consideration of the balance between the performance of reducing the high-speed peel strength and the chemical solution intrusion prevention, the number of carbon atoms of the alkyl group is preferably 8 to 20, more preferably 10 to 20, still more preferably 12 to 20 (Typically 13-20, for example 16-18).

  “Phosphanol (registered trademark)” series manufactured by Toho Chemical Industry Co., Ltd. is listed as a commercially available (poly) oxyethylene alkyl ether phosphate ester that can be preferably used as a release modifier in the technology disclosed herein. It is done. Specific examples include Phosphanol (registered trademark) RL-210, RL-310, RM-410, RS-410, ED-200, ML-220, and ML-240.

Another preferred example of the release modifier is (poly) etheramine. For example, (poly) etheramine represented by the following formula (2) can be used.
R ³ —N [— (CH ₂ CH ₂ O) _n —H] ₂ (2)
Here, n in Formula (2) is 1-20, and is typically 1-10. R ³ is a hydrocarbon group, for example, a C _10-30 saturated or unsaturated hydrocarbon group, preferably a C _10-20 (more preferably C _14-18 ) alkyl group. Preferable examples of the compound represented by the formula (2) include (poly) oxyethylene laurylamine and (poly) oxyethylene stearylamine. Of these, (poly) oxyethylene stearylamine is preferable.

Although it does not specifically limit, as a peeling regulator in the technique disclosed here, it is preferable to use that whose HLB (Hydrophile-Lipophile Balance) value is about 4-15 (more preferably 5-10). it can.
The molecular weight of the release modifier is not particularly limited. Appropriately exert the effect of containing a release modifier (that is, the effect of adjusting the value of P _L / P _H , particularly the effect of reducing P _H intensively), and suppress the decrease in adhesive residue and cohesive force In view of the above, usually, a release regulator having a molecular weight (a mass average molecular weight when the molecular weight is distributed) of about 200 to 5000 (for example, 300 to 3000) is preferable.

  The peeling regulator in the technique disclosed here can be used alone or in combination of two or more. As a peeling regulator according to a preferred embodiment, a peeling regulator containing only one or more (poly) oxyethylene alkyl ether phosphates is exemplified. As a peeling regulator according to another preferred embodiment, a peeling regulator containing a combination of a peeling regulator having a -POH group and (poly) etheramine is exemplified. For example, a release modifier containing a combination of (poly) oxyethylene alkyl ether phosphate ester and (poly) etheramine represented by the above formula (2) is preferable.

The amount of the release modifier may be a value of P _H and P _{L /} P _H of the protective sheet is set to be the preferred ranges disclosed herein. Content of the peeling regulator with respect to 100 parts by mass of the acrylic polymer can be set to 0.01 to 15 parts by mass, for example. From the viewpoint of appropriately exerting the effect of containing a release adjusting agent and suppressing the decrease in adhesiveness, usually the content of the release adjusting agent with respect to 100 parts by mass of the acrylic polymer (two or more types of release adjusting agents) In the case of using the above, the total content thereof) is suitably 0.05 to 10 parts by mass, and preferably 0.1 to 5 parts by mass.

When (poly) oxyethylene alkyl ether phosphate is used as a release modifier, the content of (poly) oxyethylene alkyl ether phosphate relative to 100 parts by mass of the acrylic polymer is, for example, 0.01 to 5 parts by mass. Preferably, it is 0.05-3 mass parts, More preferably, it is 0.1-2 mass parts.
Moreover, when (poly) etheramine is used as a release modifier, the content of (poly) etheramine with respect to 100 parts by mass of the acrylic polymer can be, for example, 0.1 to 10 parts by mass, and preferably is 0.1. 5 to 5 parts by mass.
When (poly) oxyethylene alkyl ether phosphate ester and (poly) ether amine are used in combination as a release modifier, the mass ratio of (poly) oxyethylene alkyl ether phosphate ester to (poly) ether amine is not particularly limited. However, it is usually appropriate to be about 1/5 to 5/1, and preferably about 1/3 to 3/1 (more preferably 1/1 to 1/3).

  It is preferable that the said adhesive composition contains a crosslinking agent. The type of the crosslinking agent is not particularly limited, and may be appropriately selected from various crosslinking agents usually used in the pressure-sensitive adhesive field according to, for example, the type of the crosslinkable functional group of the functional group-containing monomer. Can do. Examples of various crosslinking agents usually used in the pressure-sensitive adhesive field include isocyanate crosslinking agents such as polyisocyanates, silane crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, and metal chelate crosslinking agents. And melamine-based crosslinking agents. Such a crosslinking agent can be used individually by 1 type or in combination of 2 or more types.

  Examples of the isocyanate-based crosslinking agent include: aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; aliphatic isocyanates such as hexamethylene diisocyanate; More specifically: lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; 2,4-tolylene diisocyanate, 4 Aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate and xylylene diisocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene Diisocyanate trimer adduct (made by Nippon Polyurethane Industry Co., Ltd., trade name “Coronate HL”), isocyanurate of hexamethylene diisocyanate (Nippon Polyureta) It can be exemplified, and the like; Kogyo Co., Ltd. under the trade name "Coronate HX") isocyanate adducts such as. As an isocyanate type crosslinking agent, 1 type of such an isocyanate compound can be used individually or in combination of 2 or more types.

  Examples of the epoxy-based crosslinking agent include N, N, N ′, N′-tetraglycidyl-m-xylenediamine (manufactured by Mitsubishi Gas Chemical Company, trade name “TETRAD-X”), 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (trade name “TETRAD-C” manufactured by Mitsubishi Gas Chemical Company) and the like. Examples of the melamine-based crosslinking agent include hexamethylol melamine.

  Of these, preferred crosslinking agents include isocyanate-based crosslinking agents. The technology disclosed herein is a cross-linking agent that contains an isocyanate-based cross-linking agent and does not contain an epoxy-based cross-linking agent (typically, an isocyanate-based cross-linking agent) from the viewpoint of achieving both high chemical penetration prevention and peeling workability. In the embodiment using a cross-linking agent comprising only an agent, it can be preferably carried out. The use of the isocyanate-based crosslinking agent is also advantageous from the viewpoint that the gel fraction of the pressure-sensitive adhesive described later can be easily controlled within the preferred range disclosed herein.

  A pressure-sensitive adhesive composition according to a preferred embodiment is a crosslinking agent comprising an acrylic polymer in which a carboxyl group-containing monomer is copolymerized as a functional group-containing monomer and an isocyanate crosslinking agent (a crosslinking agent comprising only an isocyanate crosslinking agent). In combination). According to such a pressure-sensitive adhesive composition, it is possible to realize a protective sheet that achieves a high degree of compatibility between adhesion and peeling workability. Moreover, it is advantageous also from a viewpoint that it is easy to control the gel fraction of an adhesive to the preferable range indicated here. From the viewpoint of easy control of the gel fraction and adhesion to the adherend, the technology disclosed herein is such that the acrylic polymer is copolymerized with a carboxyl group-containing monomer, and the hydroxyl group-containing monomer is substantially It can preferably be carried out in a mode in which it is not copolymerized. A combination of such an acrylic polymer and a crosslinking agent containing an isocyanate crosslinking agent (typically a crosslinking agent comprising only an isocyanate crosslinking agent) is particularly preferred.

  The amount of the crosslinking agent contained in the pressure-sensitive adhesive composition is not particularly limited, but is usually 0.5 to 10 with respect to 100 parts by mass of the acrylic polymer from the viewpoint of achieving both adhesion and peeling workability. It is appropriate that the amount is about 1 part by mass (for example, 1 to 7 parts by mass, typically 2 to 7 parts by mass).

  The pressure-sensitive adhesive composition may further contain a crosslinking accelerator. The kind of crosslinking accelerator can be suitably selected according to the kind of crosslinking agent to be used. In the present specification, the crosslinking accelerator refers to a catalyst that increases the speed of the crosslinking reaction by the crosslinking agent. Examples of the crosslinking accelerator include tin (Sn) -containing compounds such as dioctyltin dilaurate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetylacetonate, tetra-n-butyltin, and trimethyltin hydroxide; N, N , N ′, N′-tetramethylhexanediamine, amines such as triethylamine, and nitrogen (N) -containing compounds such as imidazoles. Of these, Sn-containing compounds are preferred. The amount of the crosslinking accelerator contained in the pressure-sensitive adhesive composition is, for example, about 0.001 to 0.5 parts by mass (preferably 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the acrylic polymer). About mass parts). The technique disclosed here is an embodiment in which the pressure-sensitive adhesive composition does not substantially contain a crosslinking accelerator in consideration of ease of control of the gel fraction of the pressure-sensitive adhesive, adhesion to the adherend, and the like. It can be preferably implemented.

  The said adhesive composition may contain a tackifier as needed. As the tackifier, conventionally known ones can be used without any particular limitation. For example, terpene tackifier resin, phenol tackifier resin, rosin tackifier resin, aliphatic petroleum resin, aromatic petroleum resin, copolymer petroleum resin, alicyclic petroleum resin, xylene resin, epoxy tackifier Examples include an imparting resin, a polyamide tackifying resin, a ketone tackifying resin, and an elastomer tackifying resin. These can be used alone or in combination of two or more. In the case of using a tackifier, the amount used is 50 parts by mass or less (typically from 100 parts by mass of the acrylic polymer from the viewpoint of sufficiently obtaining the effect of the tackifier without reducing the properties of the acrylic polymer. Is preferably 0.1 to 30 parts by mass). In addition, the technique disclosed here can be preferably implemented in a mode in which the pressure-sensitive adhesive composition does not substantially contain a tackifier in consideration of adhesion and adhesive residue prevention.

  The pressure-sensitive adhesive composition may be prepared by blending the acrylic polymer with another polymer (arbitrary polymer) as necessary. Such an optional polymer can be blended, for example, for the purpose of increasing the cohesive strength of the pressure-sensitive adhesive. An increase in the cohesive strength of the adhesive improves the ability to prevent the chemical solution from entering from the outer edge of the protective sheet (typically, the ability to prevent the chemical solution from entering mainly due to the pressure sensitive adhesive swelling). Can contribute.

The composition of the arbitrary polymer is not particularly limited. For example, a polymer containing a carboxylic acid vinyl ester in the monomer composition can be preferably employed. As the vinyl carboxylate, vinyl acetate or vinyl propionate is preferable, and vinyl acetate is particularly preferable. Specific examples of polymers containing carboxylic acid vinyl esters in the monomer composition include vinyl chloride / vinyl acetate copolymers, vinyl chloride / vinyl acetate / acrylic monomer copolymers, vinyl chloride / vinyl propionate copolymers, and the like. Examples thereof include vinyl copolymers and ethylene / vinyl acetate copolymers.
The Tg of the arbitrary polymer is preferably more than −20 ° C., more preferably 0 ° C. or more, further preferably 20 ° C. or more, and particularly preferably 30 ° C. or more. Although the upper limit of Tg is not particularly limited, an arbitrary polymer having Tg of 120 ° C. or lower (more preferably 100 ° C. or lower) is usually preferable from the viewpoint of adhesion to the adherend surface and the like. For example, a vinyl chloride / vinyl acetate copolymer having a Tg of 40 ° C. to 70 ° C. can be preferably used.
The mass average molecular weight (Mw) of the arbitrary polymer may be, for example, about 0.5 × 10 ⁴ to 10 × 10 ⁴ . In consideration of the balance between adhesion to the adherend surface and cohesiveness, an arbitrary polymer having an Mw of 0.8 × 10 ^{4 to} 5 × 10 ⁴ (more preferably 1 × 10 ^{4 to} 3 × 10 ⁴ ) ( For example, a vinyl chloride / vinyl acetate copolymer) is preferable.

  When the above arbitrary polymer (for example, vinyl chloride / vinyl acetate copolymer) is used, the amount used can be 30 parts by mass or less with respect to 100 parts by mass of the acrylic polymer. From the viewpoint of achieving both cohesion and adhesiveness, the amount of the optional polymer used is usually 1 to 30 parts by mass (more preferably 5 to 25 parts by mass, for example 10 to 20 parts by mass) with respect to 100 parts by mass of the acrylic polymer. It is preferable that

In the technology disclosed herein, the proportion of the acrylic polymer in the solid content (adhesive forming component) in the adhesive composition is preferably more than 50% by mass. From the viewpoint of highly achieving both the chemical solution intrusion prevention property and the peeling workability, the ratio of the acrylic polymer is more preferably 70% by mass or more (for example, 80% by mass or more). In a preferred embodiment, the proportion of the acrylic polymer may be more than 85% by mass (for example, 90% by mass or more). Such embodiment is advantageous, for example, from the viewpoint of further increasing the value of P L _/ P _H.

  The technology disclosed herein is preferably implemented in an embodiment in which the solid content (adhesive forming component) of the pressure-sensitive adhesive composition includes a monomer unit derived from a carboxylic acid vinyl ester (hereinafter also referred to as a carboxylic acid vinyl ester unit). Can be done. Such a carboxylic acid vinyl ester unit can be synthesized, for example, by polymerizing a monomer material containing an alkyl (meth) acrylate and a carboxylic acid vinyl ester (typically solution polymerization) to synthesize an acrylic polymer, It can be included in the pressure-sensitive adhesive composition in the form of a monomer unit constituting a homopolymer or copolymer of a carboxylic acid vinyl ester, for example, due to blending of an arbitrary polymer containing a carboxylic acid ester. As a suitable example of the pressure-sensitive adhesive composition containing a carboxylic acid vinyl ester unit, an acrylic polymer obtained by polymerizing a monomer raw material containing an alkyl (meth) acrylate and a carboxylic acid vinyl ester, and a monomer composition having a vinyl carboxylate A pressure-sensitive adhesive composition containing an optional polymer containing an ester (for example, vinyl chloride / vinyl acetate copolymer) in combination.

  The proportion of the carboxylic acid vinyl ester unit in the solid content of the pressure-sensitive adhesive composition can be, for example, 5% by mass or more, and is preferably 10% by mass or more. From the viewpoint of improving the adhesion to an adherend (for example, a glass substrate) to achieve both high chemical solution entry prevention and peeling workability, the above ratio is preferably 20% by mass or more, and 30% by mass or more. More preferably. In addition, since the adhesiveness may decrease even if the ratio is too high, it is usually appropriate that the ratio of the carboxylic acid vinyl ester unit in the solid content of the pressure-sensitive adhesive composition is 65% by mass or less. Yes, it is preferably 55% by mass or less, and more preferably 50% by mass or less.

  The pressure-sensitive adhesive composition is an antistatic agent, slip agent, anti-blocking agent, leveling agent, plasticizer, filler, colorant (pigment, dye, etc.), pH adjustment as long as the effect of the present invention is not significantly hindered. Various additives generally used in the field of pressure-sensitive adhesives such as an agent, a dispersant, a stabilizer, an antiseptic, and an anti-aging agent may be further contained as necessary. When using such an additive, the compounding quantity can be made into the same grade as the normal compounding quantity of the adhesive composition used for formation of an adhesive layer (manufacture of a protection sheet) in the said use.

  As a method for providing the pressure-sensitive adhesive layer on the substrate, for example, a method (direct method) in which the above-mentioned pressure-sensitive adhesive composition is directly applied (typically applied) to the substrate and cured, For example, the pressure-sensitive adhesive composition is applied on the surface of a transfer sheet having peelability and cured to form a pressure-sensitive adhesive layer on the release surface, and the pressure-sensitive adhesive layer is bonded to a substrate. And a transfer method (transfer method) can be used. The curing treatment may be one or more treatments selected from drying (heating), cooling, crosslinking, additional copolymerization reaction, aging and the like. For example, a treatment simply drying a pressure-sensitive adhesive composition containing a solvent (heating treatment, etc.) or a treatment simply cooling (solidifying) a pressure-sensitive adhesive composition in a heated and melted state is also referred to as a curing treatment here. May be included. When the said hardening process includes two or more processes (for example, drying and bridge | crosslinking), these processes may be performed simultaneously and may be performed over multiple steps.

  Application of the pressure-sensitive adhesive composition can be carried out using a conventional coater such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater. From the viewpoint of promoting the crosslinking reaction and improving the production efficiency, the pressure-sensitive adhesive composition is preferably dried under heating. Depending on the type of support to which the pressure-sensitive adhesive composition is applied, for example, a drying temperature of about 40 ° C. to 150 ° C. can be employed. After drying, an aging treatment may be performed by holding at about 40 ° C. to 60 ° C. so that the crosslinking reaction further proceeds. The aging time may be appropriately selected according to the desired degree of crosslinking and the progress rate of the crosslinking reaction, and can be, for example, about 12 hours to 120 hours, typically about 12 hours to 72 hours.

  The thickness of an adhesive layer is not specifically limited, It can adjust suitably according to the objective. The thickness of the pressure-sensitive adhesive layer can be, for example, about 1 μm to 100 μm. From the viewpoint of adhesion to the adherend surface, the preferred thickness is 2 μm or more, more preferably 3 μm or more (for example, 5 μm or more, typically 7 μm or more). Further, from the viewpoint of peeling workability, the thickness of the pressure-sensitive adhesive layer is preferably 40 μm or less, and typically 30 μm or less. It is preferable that the thickness of the pressure-sensitive adhesive layer is not too large from the viewpoint of suppressing the infiltration of the chemical liquid due to the swelling of the pressure-sensitive adhesive.

The arithmetic average surface roughness of the surface of the pressure-sensitive adhesive layer (adhesive surface, that is, the surface to be adhered to the adherend) is preferably 1 μm or less, and is approximately 0.05 μm to 0.75 μm (for example, approximately 0.05 μm to 0). More preferably, it is in the range of 0.5 μm, typically about 0.1 μm to 0.3 μm. When the smoothness of the adhesive surface increases, the adhesion between the adhesive surface and the adherend surface is improved. As a result, it is possible to better prevent the chemical solution from entering the interface between the adhesive and the adherend. In addition, since the adhesive layer with high smoothness has less stress bias when peeling from the surface of the adherend, a part of the adhesive is cut off due to local stress and remains on the adherend side. Can be avoided well. Therefore, the protective sheet having such a pressure-sensitive adhesive layer on the substrate can be smoothly peeled off from the adherend without causing contamination such as adhesive residue on the adherend surface.
The arithmetic average surface roughness of the adhesive surface is measured using a general surface roughness measuring device (for example, a non-contact three-dimensional surface shape measuring device manufactured by Veeco, model “Wyko NT-3300”). Can do.

  The surface on the side of the substrate where the adhesive layer is provided does not affect the surface state of the adhesive layer (surface roughness of the adhesive surface) (that is, a factor that increases the arithmetic average surface roughness of the adhesive surface) It is preferable to have a smoothness of a level that does not become. For example, the substrate preferably has an arithmetic average surface roughness of 1 μm or less on the surface of the pressure-sensitive adhesive layer side, and is 0.05 μm to 0.75 μm (for example, approximately 0.05 μm to 0.5 μm, typically approximately More preferably, the thickness is 0.1 μm to 0.3 μm. By setting it as this structure, the smoothness of an adhesive surface also becomes high.

The gel fraction of the adhesive which comprises a protective sheet is not specifically limited, For example, it may be 20 mass% or more. From the viewpoint of improving the peeling workability (suppressing high-speed peeling strength) and the like, it is usually preferable that the gel fraction is 25% by mass or more. Increased gel fraction of the adhesive improves the prevention of chemical penetration from the outer edge of the protective sheet (typically, the ability to prevent chemical penetration due to the adhesive mainly swelling with the chemical) To do. Further, the cohesive force of the pressure-sensitive adhesive is increased, and contamination such as adhesive residue is less likely to occur when the protective sheet is peeled off. From these viewpoints, the gel fraction of the pressure-sensitive adhesive is more preferably 27% by mass or more (for example, 30% by mass or more).
The upper limit of the gel fraction is not particularly limited, but is typically 80% by mass or less, preferably 70% by mass or less, more preferably less than 60% by mass (for example, 55% by mass or less). When the gel fraction is too high, depending on the configuration of the pressure-sensitive adhesive, the adhesion to the adherend surface tends to be reduced, and chemical liquid intrusion from the interface between the pressure-sensitive adhesive and the adherend may easily occur. The technique disclosed herein can be preferably implemented in an embodiment in which the gel fraction of the pressure-sensitive adhesive is 50% by mass or less (typically 45% by mass or less, for example, 40% by mass or less) from the viewpoint of adhesion. .
The gel fraction can be adjusted by copolymerization composition of acrylic polymer (for example, use of functional group-containing monomer or polyfunctional monomer), molecular weight, cross-linking agent and other additives.

The gel fraction was measured by wrapping a measurement sample having a weight W1 in a porous sheet made of tetrafluoroethylene resin and immersing the sample in ethyl acetate for 1 week at room temperature, then drying the measurement sample and weighing the weight W2 of the ethyl acetate insoluble matter. And W1 and W2 are calculated by substituting into the following formula: gel fraction [%] = W2 / W1 × 100;
More specifically, the gel fraction can be measured by the following method. That is, about 0.1 g of a measurement sample is wrapped in a purse-like shape with a porous sheet made of tetrafluoroethylene resin having an average pore diameter of 0.2 μm, and the mouth is tied with a kite string. The total mass Wa (mg) of the tetrafluoroethylene resin porous sheet and the kite string is measured in advance. Then, the mass of the package (the total mass of the pressure-sensitive adhesive layer and the package) Wb (mg) is measured. Place this packet in a 50 mL screw tube (use one screw tube per packet) and fill the screw tube with ethyl acetate. This is allowed to stand at room temperature (typically 23 ° C.) for 7 days, and then the packet is taken out and dried at 120 ° C. for 2 hours, and the mass Wc (mg) of the package after drying is measured. The gel fraction (%) of the pressure-sensitive adhesive layer is determined by using the following formula for Wa, Wb and Wc:
Gel fraction [%] = (Wc−Wa) / (Wb−Wa) × 100
By substituting for. As the porous sheet made of tetrafluoroethylene resin, a trade name “Nitoflon (registered trademark) NTF1122” manufactured by Nitto Denko Corporation can be used. The same method can be adopted in the embodiments described later.

The protective sheet disclosed herein, 30 minutes after stuck to a glass plate in a peel angle of 180 °, the slow peel strength _{P L} measured at a tensile rate of 300 mm / min condition 0.1 N / 20 mm or more (typically Is preferably 0.2 N / 20 mm or more, for example, 0.25 N / 20 mm or more. Protection sheet shown such slow peel strength P _L is excellent in adhesion to a glass plate other adherend (workpiece). Accordingly, it is possible to effectively prevent the chemical solution from entering from the interface between the pressure-sensitive adhesive and the adherend. The upper limit of the low speed peel strength _{P L} is not particularly limited, usually, slow peel strength _{P L} is 5N / 20 mm or less (e.g., 3N / 20 mm or less, typically 2N / 20 mm or less) suitably to be.
Slow peel strength P _L can be measured by the following method. A protective sheet to be used for measurement is cut into a 20 mm × 60 mm square shape with the MD (Machine Direction) of the base material as the longitudinal direction to produce a test piece. The pressure-sensitive adhesive layer side of the test piece is attached to the glass substrate by reciprocating a 2 kg roller once. After holding this in an environment of 25 ° C. and 50% RH for 30 minutes, using a tensile tester (manufactured by Shimadzu Corporation, trade name “Tensilon”), in accordance with JIS Z0237, 25 ° C., 50% Under an RH environment, 180 ° peel adhesion to glass is measured under the conditions of a peel angle of 180 ° and a tensile speed of 300 mm / min. As the glass substrate, trade name “MICROSLIDE GLASS” manufactured by Matsunami Glass Co., Ltd. can be used. The same method can be adopted in the embodiments described later.

The protective sheet disclosed herein, also adhered to the glass plate peeling angle 180 ° after 30 minutes, high-speed peel strength P _H measured at a tensile rate of 10 m / min condition 3N / 20 mm or less (more preferably 2.5N / 20mm or less, for example, 2N / 20mm or less, typically 1.5N / 20mm or less). Protection sheet shown such high-speed peel strength P _H, the protective rupture of the sheet (tearing) and adhesive residue is less likely to occur when it is peeled from the glass plate other adherend (workpiece), applied to the adherend The load is also small. Accordingly, the peeling workability is excellent. Fast peel strength but _P lower limit of _H is not particularly limited, usually, it is suitable that fast peel strength _{P H} is 0.05 N / 20 mm or more (typically 0.1 N / 20 mm or more).
Measurement of high-speed peeling strength P _H, in addition to the pulling speed and 10 m / min can be carried out in the same manner as in the measurement of low-speed peel strength P _L. The same method can be adopted in the embodiments described later.

In the protective sheet disclosed herein, the ratio (P _L / P _H ) of the low-speed peel strength P _{L to} the high-speed peel strength P _H is preferably greater than 0.5, and more preferably 1 or more. P L _/ P _H is greater than 0.5 protective sheet, is light peeling at high speed peeling is heavy split at a low speed. Therefore, the chemical solution intrusion preventing property and the peeling workability can be achieved in a balanced manner. For example, even when the gel fraction of the pressure-sensitive adhesive is less than 60% by mass (typically 50% by mass or less), the protective sheet is less likely to be stretched or left behind when the protective sheet is peeled off. In a preferred embodiment of the protective sheet disclosed herein, P _L / P _H is 2 or more (more preferably 3 or more, for example, 4 or more). According to such a protective sheet, the chemical solution intrusion prevention property and the peeling workability can be achieved at a higher level.

The protective sheet disclosed here has a strength T _M25 when stretched to 10% in MD (Machine Direction) at a temperature of 25 ° C. and 10% stretch in TD (Transverse Direction) at the same temperature. It is preferable that at least one of the strengths T _T25 is 1 N / cm to ₂₅ N / cm. It is more preferable that both T _M25 and T _T25 satisfy the numerical value range of strength at the time of 10% stretching described above. When the strength at the time of 10% stretching (T _M25 , T _T25 ) is 1 N / cm or more, the protective sheet has an appropriate hardness, and thus is easy to handle. For example, when affixing to an adherend, wrinkles, floats, wrinkles, and the like are less likely to occur and the application is easy. Further, since the protective sheet has a strength higher than a predetermined level, it is possible to prevent inconveniences such as tearing of the protective sheet at the time of peeling, and the peeling workability is good. The strength at the time of 10% stretching (T _M25 , T _T25 ) is preferably 22 N / cm or less (for example, 20 N / cm or less, typically 18 N / cm or less). When the strength (T _M25 , T _T25 ) when the protective sheet is stretched by 10% is ₂₅ N / cm or less, even if the surface of the adherend has a step, the surface shape can be satisfactorily followed. It is excellent in chemical solution penetration prevention.
Here, the strength at the time of 10% stretching (tensile tension) is a test having a width of 10 mm cut out along each measurement direction (T _M25 , T _T25 ) at a temperature of 25 ° C. in accordance with JIS K7127. This refers to the tensile tension when a piece is stretched 10% under the condition of a tensile speed of 300 mm / min.

The protective sheet disclosed here has at least a bending rigidity value D _M25 to MD at a temperature of 25 ° C. and a bending rigidity value D _T25 to TD at the same temperature from the viewpoint of the workability of peeling and handling of the protective sheet. One is preferably 1.5 × 10 ⁻⁵ Pa · m ³ or more (for example, 2 × 10 ⁻⁵ Pa · m ³ or more, typically 3 × 10 ⁻⁵ Pa · m ³ or more). Further, from the viewpoint of surface shape followability and the like, at least one of _{DM 25} and _DT25 is 10 × 10 ⁻⁵ Pa · m ³ or less (for example, 9.5 × 10 ⁻⁵ Pa · m ³ or less, typically 9 × 10 ⁻⁵ Pa · m ³ or less) is preferable. It is more preferable that both D _M25 and D _T25 satisfy the numerical range of the bending rigidity value described above.

The bending stiffness value D _M25 is an equation when the thickness of the base material is h, the Poisson's ratio of the base material is V, and the tensile elastic modulus to MD at a temperature of 25 ° C. of the protective sheet is E _M25 :
^{_{D M25 = E M25 h 3/}} 12 (1-V 2);
Is a value obtained by The bending stiffness value D _T25 is also obtained using the tensile elastic modulus E _T25 to TD in the same manner as in the case of D _M25 . In addition, since the bending rigidity value of an adhesive layer is very small compared with the bending rigidity value of a base material, the bending rigidity value of a protective sheet can be substantially equivalent to the bending rigidity value of a base material. Therefore, the bending rigidity values D _M25 and D _T25 of the protective sheet refer to values converted per cross-sectional area of the base material constituting the protective sheet. The cross-sectional area of the substrate is calculated based on the thickness of the substrate. The thickness h of the base material is a value obtained by subtracting the thickness of the pressure-sensitive adhesive layer from the actual measurement value of the thickness of the protective sheet. The Poisson's ratio V is a value (dimensionless number) determined by the material of the base material. When the material is a resin, 0.35 can usually be adopted as the value of V.

In the protective sheet disclosed herein, at least one of the tensile elastic modulus E _M25 to MD at a temperature of 25 ° C. and the tensile elastic modulus E _T25 to TD at the same temperature is preferably 50 MPa or higher (eg, 100 MPa or higher, typically Is 150 MPa or more). This protective sheet tends to be excellent in handleability in a room temperature environment. Further, E _M25 and E _T25 of the protective sheet can be 9000 MPa or less (for example, 8000 MPa or less, typically 4000 MPa or less). In such a protective sheet, the bending rigidity values D _M25 and D _{T25 tend to} be appropriate values. Therefore, it tends to be excellent in adhesiveness even on a stepped surface.

The tensile elastic modulus E _M25 , _ET25 of the protective sheet is obtained by cutting out a test piece having a predetermined width along the MD or TD from the protective sheet, and in accordance with JIS K7161, the test piece is pulled at a temperature of 25 ° C. at a tensile speed of 300 mm / min. It can be calculated from linear regression of a stress-strain curve obtained by stretching to MD or TD under the conditions of In addition, since the tensile elasticity modulus of an adhesive layer is very small compared with the tensile elasticity modulus of a base material, the tensile elasticity modulus of a protective sheet can be substantially equivalent to the tensile elasticity modulus of a base material. Accordingly, in this specification, the tensile elastic modulus E _M25 , E _T25 of the protective sheet refers to a value converted per cross-sectional area of the base material constituting the protective sheet. The cross-sectional area of the substrate is calculated based on the thickness of the substrate. The thickness of the substrate is a value obtained by subtracting the thickness of the pressure-sensitive adhesive layer from the actual measurement value of the thickness of the protective sheet.

  The strength at the time of 10% stretching of the base material, the bending stiffness value at a predetermined temperature, and the tensile elastic modulus are substantially equal to the strength at the time of 10% stretching of the protective sheet, the bending stiffness value at a predetermined temperature and the tensile elastic modulus as described above. possible. Therefore, a protective sheet satisfying each of the above characteristics can be obtained by selecting, for example, the type of base material (for example, blending components and blending ratio), thickness, and the like.

  The protective sheet may be in the form of a protective sheet with a release liner in which a release liner is disposed on the surface of the pressure-sensitive adhesive layer before use (before application to an adherend). When the release liner is placed on the adhesive surface and the surface facing the adhesive surface (release surface) is excellent in smoothness, the smoothness of the adhesive surface (adhesive surface) is more stable until the protective sheet is used. Can be maintained.

As the release liner, various papers (which may be papers with a resin laminated on the surface), resin films, and the like can be used without particular limitation. When a resin film is used as the release liner, preferred examples of the resin component constituting the resin film include polyolefin resins, polyester resins such as PET, polyamide resins, polycarbonate resins, polyurethane resins and the like. A release liner made of a resin material containing one kind of such resin may be used, or a release liner made of a resin material in which two or more kinds of resins (for example, PE and PP) are blended may be used. . Such a resin film for a release liner can be produced by appropriately adopting a general film forming method as in the case of a resin sheet for a substrate. The structure of the release liner may be a single layer or a multilayer structure of two or more layers.
When the transfer method is employed as a method for providing the pressure-sensitive adhesive layer on the substrate, the same transfer sheet and release liner may be used. For example, a base material is bonded to the pressure-sensitive adhesive layer formed on the release surface of the transfer sheet, the pressure-sensitive adhesive layer is transferred to the base material, and this transfer sheet is left as it is on the pressure-sensitive adhesive layer and used as a release liner. be able to. Thus, the mode in which the transfer sheet also serves as a release liner is preferable from the viewpoints of productivity improvement, material cost reduction, waste amount reduction, and the like.

  The thickness of the release liner is not particularly limited, and may be about 5 μm to 500 μm (for example, about 10 μm to 200 μm, typically about 30 μm to 200 μm). The release surface of the release liner (the surface disposed in contact with the adhesive surface) is subjected to a release treatment with a conventionally known release agent (for example, general silicone-based, long-chain alkyl-based, fluorine-based, etc.) as necessary. May be. The back surface of the peeling surface may be subjected to a peeling treatment, may be subjected to a surface treatment other than the peeling treatment, or may not be treated.

  The arithmetic average surface roughness of the surface of the release liner on the side of the pressure-sensitive adhesive layer is 0.05 μm to 0.75 μm (for example, about 0.05 μm to 0.5 μm, typically about 0.1 μm to 0.3 μm) is preferable. Thereby, the smoothness of the pressure-sensitive adhesive surface (adhesive surface) can be kept high until the protective sheet is used. High smoothness of the pressure-sensitive adhesive surface is advantageous in preventing chemical solution from entering from the interface between the pressure-sensitive adhesive and the adherend. Moreover, it is preferable also from a viewpoint of adhesive residue prevention. For the same reason, in the protective sheet in the form of protecting the adhesive surface until the protective sheet is used by bringing the surface (adhesive surface) of the adhesive layer into contact with the back surface of the base material, the arithmetic average of the back surface of the base material is used. The surface roughness is preferably 0.05 μm to 0.75 μm (for example, approximately 0.05 μm to 0.5 μm, typically approximately 0.1 μm to 0.3 μm).

  The protective sheet disclosed herein can be used as a protective sheet for affixing to a desired part of an adherend and protecting the part. The pressure-sensitive adhesive used for this protective sheet has high adhesion to the adherend. Accordingly, the outer edge of the protective sheet is excellent in the performance of preventing the intrusion of a chemical solution (particularly an aqueous chemical solution, typically an acidic chemical solution) from the interface between the pressure-sensitive adhesive and the adherend. As a result, it is possible to reliably prevent the chemical solution from entering a region not intended to be exposed to the chemical solution and protect the surface. In addition, since it has both high adhesion and light release at the time of high-speed peeling, it is difficult to damage the protective sheet itself or the adherend, and it is difficult for adhesive residue to remain on the adherend surface. Accordingly, the peeling workability is excellent.

  Taking advantage of such features, the protective sheet disclosed herein can be used, for example, to reduce the thickness of the glass or to remove the burrs and microcracks formed on the cut end surface of the glass. Etching treatment that dissolves in the etching solution), etching treatment that partially corrodes the metal surface with a chemical solution (etching solution) for decoration and printability, circuit boards (printed boards, flexible printed circuit boards (FPC), etc.) It can be suitably used in a plating process or the like in which the connection terminal portion is partially plated with a chemical solution (plating solution).

  In addition, for example, when the protective sheet is attached to a range including the outer edge of the adherend and the chemical treatment is performed, when the chemical liquid partially enters from the outer edge of the adherend (the outer edge of the region where the protective sheet is attached), The smoothness of the outer edge (edge) of the adherend may be impaired due to the influence of the chemical solution. When the smoothness of the edge of the adherend is impaired, in particular, a brittle adherend such as a glass substrate may cause inconveniences such as a decrease in strength of the adherend. Since the protective sheet disclosed here is excellent in the performance of preventing the chemical solution from entering from the outer edge of the protective sheet, it is possible to effectively prevent an event that the smoothness of the edge of the adherend is lowered.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to the specific examples. In the following description, “part” and “%” are based on mass unless otherwise specified.

[Production of substrate]
<Production Example 1>
A mixture of 80 parts of polypropylene (PP), 10 parts of polyethylene (PE) and 10 parts of ethylene propylene rubber (EPR) was extruded by the T-die method to form a film-like substrate having a thickness of 40 μm (PP / PE / EPR blend film) A was obtained. One side of the substrate A was subjected to corona discharge treatment.
Here, as PP, crystalline homopolypropylene having a resin density of 0.905 and random polypropylene having a resin density of 0.900 were used at a mass ratio of 1: 1. As PE, low-density polyethylene “Petrocene (registered trademark) 205” manufactured by Tosoh Corporation was used. As EPR, “Tuffmer (registered trademark) P0180” manufactured by Mitsui Chemicals, Inc. was used.

<Production Example 2>
Low-density polyethylene (“Petrocene (registered trademark) 180” manufactured by Tosoh Corporation) is molded by an inflation molding machine at a die temperature of 160 ° C. to obtain a film-like substrate (PE film) B1 having a thickness of 60 μm. It was. One side of the substrate B1 was subjected to corona discharge treatment.

<Production Example 3>
Low-density polyethylene (“Petrocene (registered trademark) 180” manufactured by Tosoh Corporation) is molded by an inflation molding machine at a die temperature of 160 ° C. to obtain a film substrate (PE film) B2 having a thickness of 40 μm. It was. One side of the substrate B2 was subjected to corona discharge treatment.

[Preparation of pressure-sensitive adhesive composition]
<Preparation Example 1>
In a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 263 parts of toluene as a polymerization solvent, 100 parts of 2-ethylhexyl acrylate as a monomer raw material, 80 parts of vinyl acetate and 5 parts of acrylic acid, a peroxide system As a polymerization initiator, 0.3 part of benzoyl peroxide (BPO, “Nyper (registered trademark) BW” manufactured by NOF Corporation) was added, and nitrogen reflux was performed at room temperature for 1 hour. Next, the temperature of the container contents was raised to 63 ° C., and polymerization was performed in a nitrogen stream for 6 hours. Thereafter, the temperature of the container contents was raised to 80 ° C. and aged for 6 hours to obtain a solution of acrylic polymer A. Polyoxyethylene alkyl ether phosphate ester (“Phosphanol (registered trademark) RL-210 manufactured by Toho Chemical Industry Co., Ltd.) was used as a release modifier for 100 parts of the solid content of the acrylic polymer A solution thus obtained. ", 0.3 parts of HLB 5.4), 5 parts of an isocyanate-based crosslinking agent (" Coronate (registered trademark) L "manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent, so that the solid content is 20% Toluene was added to obtain an adhesive composition A. The Tg of the acrylic polymer A calculated from the Fox equation is −32 ° C.

<Preparation Example 2>
In Preparation Example 1, instead of 0.3 part of “Phosphanol (registered trademark) RL-210”, “Phosphanol (registered trademark) RM-410” (polyoxyethylene alkyl ether manufactured by Toho Chemical Industry Co., Ltd.) 1 part of phosphate ester, HLB 5.8) was used as a release modifier. In other respects, a pressure-sensitive adhesive composition B was obtained in the same manner as in Preparation Example 1.

<Preparation Example 3>
In Preparation Example 2, polyoxyethylene stearylamine (“Nymine (registered trademark) S-204” manufactured by NOF Corporation, HLB 8.0) as a release adjusting agent with respect to a solid content of 100 parts of the acrylic polymer A solution. 2 parts and 15 parts of a vinyl chloride copolymer (Tg 64 ° C., weight average molecular weight of about 18000) were further blended. Otherwise, the pressure-sensitive adhesive composition C was obtained in the same manner as in Preparation Example 2.

<Preparation Example 4>
For 100 parts of the solid content of the acrylic polymer A solution obtained in the same manner as in Preparation Example 1, 5 parts of an isocyanate-based crosslinking agent (“Coronate (registered trademark) L” manufactured by Nippon Polyurethane Industry Co., Ltd.) was added as a crosslinking agent. Toluene was added so that the solid content was 20%, and an adhesive composition D was obtained.

<Preparation Example 5>
An epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., “TETRAD (registered trademark) -C”) 2 as a crosslinking agent with respect to 100 parts of the solid content of the acrylic polymer A solution obtained in the same manner as in Preparation Example 1. The pressure-sensitive adhesive composition E was obtained by adding toluene so that the solid content was 20%.

<Preparation Example 6>
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, a dropping funnel and a stirring device, 182 parts of toluene as a polymerization solvent, 100 parts of 2-ethylhexyl acrylate and 4 parts of 2-hydroxyethyl acrylate as a monomer raw material, azo-based polymerization 2,2 'as initiator
-Azobis (2-methylpropionitrile) (Wako Pure Chemical Industries, Ltd., AIBN) 0.2 part was put, and nitrogen reflux was performed at room temperature for 1 hour. Next, the temperature of the container contents was raised to 61 ° C., and polymerization was performed in a nitrogen stream for 5 hours. Thereafter, the temperature of the container contents was raised to 70 ° C. and aged for 5 hours to obtain a solution of acrylic polymer F. For 100 parts of the solid content of the acrylic polymer F solution thus obtained, 4 parts of an isocyanate-based crosslinking agent (“Coronate (registered trademark) L” manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent and as a crosslinking accelerator Dioctyltin dilaurate (Tokyo Fine Chemical Co., Ltd. “Environizer OL-1”) 0.02 part was added, acetylacetone was added as a solvent so that the amount of the solvent was 4%, and the solid content was 20%. Toluene was added so that an adhesive composition F was obtained. The Tg of the acrylic polymer F calculated from the Fox equation is −68.3 ° C.

[Preparation of protective sheet]
<Example 1>
Two base materials A were prepared. The pressure-sensitive adhesive composition A was applied to the corona-treated surface of the first substrate A and dried at 80 ° C. for 1 minute to form a pressure-sensitive adhesive layer having a thickness of about 10 μm. The non-corona-treated surface of the second substrate A was bonded to this pressure-sensitive adhesive layer, and aged at 50 ° C. for 2 days (48 hours) to obtain a protective sheet according to this example.

<Example 2>
As the substrate C, a polyethylene terephthalate film (“Lumirror (registered trademark) S-10” manufactured by Toray Industries, Inc.) having a thickness of 38 μm was prepared. The adhesive composition B was applied to one side of the substrate C and dried at 80 ° C. for 1 minute to form an adhesive layer having a thickness of about 10 μm. A silicone-treated surface of a polyethylene terephthalate film (Mitsubishi Chemical Polyester Film Co., Ltd., “Diafoil (registered trademark) MRF38”) having a thickness of 38 μm treated on one side with a silicone-based release agent was bonded to this adhesive layer. A protective sheet according to this example was obtained by aging at 50 ° C. for 2 days.

<Example 3>
The adhesive composition C was applied to one side of the substrate C and dried at 80 ° C. for 1 minute to form an adhesive layer having a thickness of about 10 μm. A silicone-treated surface of a polyethylene terephthalate film (Mitsubishi Chemical Polyester Film Co., Ltd., “Diafoil (registered trademark) MRF38”) having a thickness of 38 μm treated on one side with a silicone-based release agent was bonded to this adhesive layer. A protective sheet according to this example was obtained by aging at 50 ° C. for 2 days.

<Example 4>
Two base materials B1 were prepared. The pressure-sensitive adhesive composition C was applied to the corona-treated surface of the first substrate B1, and dried at 80 ° C. for 1 minute to form a pressure-sensitive adhesive layer having a thickness of about 10 μm. The non-corona-treated surface of the second base material B1 was bonded to this pressure-sensitive adhesive layer and aged at 50 ° C. for 2 days to obtain a protective sheet according to this example.

<Example 5>
Two base materials B2 were prepared. The pressure-sensitive adhesive composition D was applied to the corona-treated surface of the first base material B2, and dried at 80 ° C. for 1 minute to form a pressure-sensitive adhesive layer having a thickness of about 10 μm. The non-corona-treated surface of the second base material B2 was bonded to this pressure-sensitive adhesive layer and aged at 50 ° C. for 2 days to obtain a protective sheet according to this example.

<Example 6>
A protective sheet according to this example was obtained in the same manner as in Example 4 except that the pressure-sensitive adhesive composition E was used in place of the pressure-sensitive adhesive composition C.

<Example 7>
A protective sheet according to this example was obtained in the same manner as in Example 4 except that the pressure-sensitive adhesive composition F was used in place of the pressure-sensitive adhesive composition C, and the thickness of the pressure-sensitive adhesive layer was about 20 μm.

[Gel fraction measurement]
About 0.1 g of the adhesive collected from the protective sheet after aging, a porous sheet made of tetrafluoroethylene resin (trade name “Nitoflon (registered trademark) NTF1122” manufactured by Nitto Denko Co., Ltd.) with a total mass of Wa and silk thread And the total mass Wb of this wrap was weighed. The package was immersed in a solvent (ethyl acetate) and allowed to stand at 23 ° C. for 7 days, and then dried at 120 ° C. for 2 hours. The mass Wc of the package after drying was measured. The above-mentioned Wa, Wb and Wc were substituted into the following formula to calculate the gel fraction of the pressure-sensitive adhesive.
Gel fraction [%] = (Wc−Wa) / (Wb−Wa) × 100

[Evaluation of chemical penetration prevention]
Prepare a glass substrate made by Matsunami Glass Industry Co., Ltd., trade name “MICROSLIDE GLASS” (length 76 mm, width 26 mm, thickness 1.3 mm), and visually observe the edge (outer edge) to obtain a smooth shape ( That is, it was confirmed that the shape was straight without any unevenness. A test tape was prepared by applying a protective tape to each of the front and back surfaces of the glass substrate. This sample was allowed to stand for 30 minutes.
100 mL of 20% hydrofluoric acid (HF) aqueous solution was poured into a plastic container having a length of 100 mm, a width of 100 mm, and a height of 30 mm, and the sample after standing for 30 minutes was submerged therein and allowed to stand for 3 hours.
After 3 hours, a sample was taken out of the 20% aqueous hydrofluoric acid solution using polyethylene tweezers, sufficiently washed with water, and dried at 50 ° C. for 2 hours.
After drying, the protective sheet was peeled off from the glass substrate, the front and back surfaces of the glass substrate (that is, the region where the protective sheet was attached) were visually confirmed, and the presence / absence of chemical penetration was evaluated according to the following two levels.
○: No dissolution due to infiltration of the chemical solution was observed on either the front surface or the back surface.
X: Dissolution by the penetration of the chemical solution was confirmed on at least one of the front surface and the back surface.
In addition, operation which peels off a protection sheet from a glass substrate was performed by the operator peeling in a 180 degree direction manually with the tensile speed of about 10 m / min in the measurement environment of 25 degreeC and 50% RH.

[Evaluation of edge smoothness]
In the evaluation of the chemical solution intrusion prevention property, the edge of the glass substrate after the protective sheet was peeled off was visually observed again, and the smoothness of the edge was evaluated according to the following two levels.
○: The edge was a straight shape without irregularities.
X: Unevenness was recognized at the edge.

[Peeling workability evaluation]
In the evaluation of the chemical solution intrusion prevention property, the workability when peeling the protective sheet from the glass plate was evaluated according to the following two levels.
○: The film can be smoothly peeled off, and the protective sheet was not stretched or cut.
X: Peeling was heavy and elongation of the protective sheet was observed.

[Low speed peel strength measurement]
The low-speed peel strength for glass was measured under the following conditions.
Measurement environment: 25 ° C, 50% RH
Specimen size: width 20mm, length 60mm
Tensile speed: 300 mm / min Peeling direction: 180 °
Size of protective sheet: 20 mm × 60 mm (cut in the MD direction as the longitudinal direction)
Substrate: Glass substrate manufactured by Matsunami Glass Industry Co., Ltd., trade name “MICROSLIDE GLASS”, size 1.3 mm × 65 mm × 165 mm
Operation method: A protective sheet was pressed against the surface of the adherend by reciprocating a 2 kg roller, and allowed to stand in the measurement environment for 30 minutes, and then the low-speed peel strength was measured.

[High speed peel strength measurement]
The high-speed peel strength for the glass was measured in the same manner as the low-speed peel strength measurement except that the tensile speed was 10 m / min.

  Table 1 shows the evaluation results of the protective sheets according to Examples 1 to 7.

As shown in Table 1, a low-speed peel strength _{P L} is 0.1 N / 20 mm or more (more specifically 0.25 N / 20 mm or higher), high-speed peeling strength _{P H} is 3N / 20 mm or less (more specifically 1.5N / 20 mm or less), and the protective sheets of Examples 1 to 4 having a gel fraction in the range of 25% to 70% are all excellent in chemical solution intrusion prevention and have high edge smoothness. Peeling workability was also good. In any of these protective sheets, no adhesive residue on the adherend surface was observed in the high-speed peel strength measurement.
On the contrary, in Example 5 Fast peel strength P _H is too high, the elongation of the protective sheet was observed in the peeling workability evaluating. Further, adhesive residue on the adherend surface was observed in the high-speed peel strength measurement. Protective sheet Examples 6 and 7, the low-speed peeling strength P _L although 0.1 N / 20 mm or more, since the gel fraction is too high then insufficient adhesion to an adherend, of the chemical to the surface of the glass It was inferior in performance to prevent intrusion and to keep the edge smooth. The protective sheet of Example 6, there was a fire in the peeling workability fast peel strength P _H is too high.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

DESCRIPTION OF SYMBOLS 1 Base material 2 Adhesive layer 3 Release liner 10 Protection sheet for chemical | medical solution processing

Claims (6)

A protective sheet for chemical treatment comprising a substrate and an adhesive layer provided on one side of the substrate,
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive mainly composed of an acrylic polymer,
Adhered to the glass plate peeling angle 180 ° after 30 minutes, low speed peel strength _{P L} measured at a tensile rate of 300 mm / min condition is at 0.1 N / 20 mm or more,
30 minutes later attached to a glass plate in a peel angle of 180 °, a tensile rate of 10 m / fast peel strength is measured in minutes condition _{P H} is not more than 3N / 20 mm,
Wherein the ratio of low-speed peeling strength _{P L} with respect to high-speed peeling strength _{P H (P L / P H} ) is greater than 0.5, and,
The protective sheet for chemical | medical solution processing whose gel fraction of the said acrylic adhesive is 25 to 70 mass%. Wherein the ratio of the high-speed peel strength _{P H} slow peel strength to _{P L (P L / P H} ) is 1 or more, the protective sheet for chemical treatment according to claim 1.   The said adhesive layer is a protective sheet for chemical | medical solution processing of Claim 1 or 2 formed from the adhesive composition containing a peeling regulator.   The said acrylic adhesive is a protective sheet for chemical | medical solution treatment as described in any one of Claim 1 to 3 which contains the monomer unit derived from carboxylic acid vinyl ester in a ratio higher than 20 mass%. The acrylic polymer is synthesized by polymerizing a monomer raw material containing an alkyl (meth) acrylate and a carboxylic acid vinyl ester,
The protective sheet for chemical | medical solution processing as described in any one of Claim 1 to 4 whose content rate of the said carboxylic acid vinyl ester in the said monomer raw material is higher than 20 mass%.   The said adhesive layer is a protective sheet for chemical | medical solution processing as described in any one of Claim 1 to 5 formed from the adhesive composition containing the said acrylic polymer and isocyanate type crosslinking agent.

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