JPWO2016114100A1 - Masking tape - Google Patents

Abstract

There is provided a masking tape comprising a support comprising a paper substrate and an adhesive layer on the first side of the support. The pressure-sensitive adhesive layer contains a rubber polymer and an acrylic polymer, and the weight ratio of the rubber polymer to the acrylic polymer is 40/60 or more and 95/5 or less.

Description

The present invention relates to a masking tape. In detail, it is related with the masking tape used suitably in the case of coating etc.
This application claims priority based on Malaysian patent application PI2015010007 filed on Jan. 16, 2015, the entire contents of which are incorporated herein by reference.

  A masking pressure-sensitive adhesive tape for coating (hereinafter referred to as “masking tape”) is used to mask a portion that is not intended for coating. Such a masking tape generally has a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive; hereinafter the same) on one side of a sheet-like support, and can be attached to a mask object via the pressure-sensitive adhesive. It is configured. A paper substrate such as Japanese paper or crepe paper is preferably used for the support in the masking tape for painting. Patent document 1 is illustrated as a technical document regarding the masking tape using a crepe paper. Patent Documents 2 and 3 are technical documents related to water-dispersed pressure-sensitive adhesives and pressure-sensitive adhesive sheets, but do not disclose a masking tape using a paper base material.

Japanese Patent Application Publication No. 2012-516382 Japanese Patent Application Publication No. 2013-7024 Japanese Patent Application Publication No. 2008-163095

  The masking tape for painting is peeled off from the mask object after the painting is completed. Therefore, the masking tape is required to have a property that hardly changes the appearance of the mask object. Specific examples of the appearance change mentioned here include that the adhesive of the masking tape remains on the surface of the mask object, and that the mask object has fogging (shadows) or dents.

  The present invention relates to an improvement of a masking tape provided with a paper substrate, and an object thereof is to provide a masking tape that hardly changes in appearance on a mask object after peeling.

  One masking tape disclosed herein includes a support including a paper substrate and an adhesive layer on the first surface of the support. The pressure-sensitive adhesive layer includes a rubber polymer and an acrylic polymer. The weight ratio of the rubber polymer to the acrylic polymer (rubber polymer / acrylic polymer) is typically 40/60 or more and 95/5 or less. The thickness of the said adhesive layer can be 5 micrometers or more, for example. The pressure-sensitive adhesive layer can be obtained, for example, from a water-dispersed pressure-sensitive adhesive composition containing the rubber polymer and the acrylic polymer.

  The pressure-sensitive adhesive layer may further contain a tackifier resin. The content of the tackifying resin can be, for example, 50 parts by weight or less with respect to 100 parts by weight of the total amount of the rubber polymer and the acrylic polymer. As said tackifier resin, what has a softening point of 90 degreeC or more can be used preferably.

The basis weight of the paper base material is preferably 15 g / m ² or more and 150 g / m ² or less. The thickness of the paper substrate is preferably 20 μm or more and 800 μm or less.

  The masking tape which concerns on a preferable one aspect | mode may have the peeling strength with respect to a stainless steel (SUS) board 1.0N / 18mm or more. The masking tape which concerns on another preferable one aspect | mode may have a peeling strength with respect to a SUS board of 10.0 N / 18mm or less.

  The masking tape disclosed here is suitable as a masking tape used for exterior coating of a transport machine, for example.

FIG. 1 is a schematic cross-sectional view illustrating a configuration of a masking tape according to an embodiment.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention 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. Further, various physical properties listed in the present specification mean values measured by the methods described in Examples described later unless otherwise specified.

In this specification, the “pressure-sensitive adhesive” refers to a material that exhibits a soft solid (viscoelastic body) state in a temperature range near room temperature and adheres to an adherend by pressure. The adhesive here is generally defined as “CA Dahlquist,“ Adhesion: Fundamental and Practice ”, McLaren & Sons, (1966) P. 143”, and generally has a complex tensile modulus E ^* (1 Hz). <10 < ⁷ > dyne / cm < ² > material (typically a material having the above properties at 25 [deg.] C.). The pressure-sensitive adhesive in the technology disclosed herein can be grasped as a solid component (nonvolatile content) of the pressure-sensitive adhesive composition or a constituent component of the pressure-sensitive adhesive layer.

  In this specification, “(meth) acryloyl” means acryloyl and methacryloyl comprehensively. Similarly, “(meth) acrylate” means acrylate and methacrylate, and “(meth) acryl” generically means acrylic and methacryl.

  In this specification, “acrylic polymer” means a polymer containing more than 50% by weight of monomer units derived from a monomer having at least one (meth) acryloyl group in one molecule as monomer units constituting the polymer. Say. Hereinafter, a monomer having at least one (meth) acryloyl group in one molecule is also referred to as an “acrylic monomer”. The acrylic polymer in this specification is defined as a polymer containing more than 50% by weight of monomer units derived from an acrylic monomer.

  In this specification, the “water dispersion type” means a form in which at least a part of the components are dispersed in water. For example, the “water-dispersed pressure-sensitive adhesive composition” means that the composition contains a pressure-sensitive adhesive composition and water, and a part of the pressure-sensitive adhesive composition is dispersed in water. The “dispersion” means a state where at least a part of the components are not dissolved in water, and includes a suspended state and an emulsified state.

  The concept of “masking tape” in this specification may include what is called a “masking sheet”. The masking tape disclosed herein is typically configured as a pressure-sensitive adhesive sheet having a size in the longitudinal direction larger than the size in the width direction, and preferably in the length direction in comparison with the width direction. Is configured as a large strip-like adhesive sheet.

<Support>
[Paper base]
The paper substrate in the technology disclosed herein can be crepe paper, Japanese paper, kraft paper, glassine paper, high-quality paper, synthetic paper, topcoat paper, and the like. Among these, a preferable paper base material includes crepe paper or Japanese paper that can be usually used as a base material for a masking tape. Japanese paper may be beaten wood pulp or a mixture of one or more synthetic short fibers. Examples of the synthetic short fiber material include vinylon, nylon, polyester, polypropylene, and polyvinyl chloride.

  The thickness of the paper substrate can be, for example, 20 μm to 800 μm, usually 30 μm to 450 μm. The more preferable thickness may vary depending on the type of paper base material. For example, when the paper substrate is crepe paper, the thickness can be, for example, 800 μm or less, usually 300 μm or less, preferably 200 μm or less, more preferably 150 μm or less. The thickness of the crepe paper can be, for example, 40 μm or more, usually 50 μm or more, preferably 70 μm or more, more preferably 100 μm or more. For example, when the paper base material is Japanese paper, the thickness may be, for example, 300 μm or less, usually 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less. The thickness of the Japanese paper can be, for example, 20 μm or more, usually 30 μm or more, preferably 40 μm or more, more preferably 50 μm or more.

The basis weight of the paper substrate, for example ^{15g / m 2 ~150g / m 2} , preferably be a ^{20g / m 2 ~100g / m 2} . The basis weight when the paper substrate is crepe paper, preferably ^{35g / m 2 ~80g / m 2} , more preferably be ^{50g / m 2 ~70g / m 2} . The basis weight of the case the paper substrate is Japanese paper, for example ^{15g / m 2 ~100g / m 2} , there preferably ^{25g / m 2 ~70g / m 2} , more preferably ^35g / ^{m 2 ~60g} / m 2 obtain.

The paper base material may further contain a general resin material, a filler, a colorant, and the like that can be used for the paper base material of the pressure-sensitive adhesive sheet or the masking tape, if necessary.
For example, a paper base material (for example, crepe paper) is impregnated with a general impregnating agent in the field of crepe paper such as natural rubber, isoprene, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber, acrylonitrile butadiene styrene rubber and the like. May be. The amount of the impregnating agent is not particularly limited, and may be, for example, 40 to 60% by weight, more preferably 46 to 52% by weight, based on the total weight of the paper substrate.

[Air permeability]
The air permeability of the paper substrate is not particularly limited. For example, a paper substrate having an air permeability in the range of 0.5 to 100 seconds / 100 mL can be preferably used. More preferable air permeability may vary depending on the type of paper substrate. For example, the air permeability when the paper substrate is crepe paper can typically be 5-100 seconds / 100 mL, preferably 10-50 seconds / 100 mL, more preferably 15-35 seconds / 100 mL. The air permeability when the paper substrate is Japanese paper is typically 0.5 to 20 seconds / 100 mL, preferably 0.5 to 10 seconds / 100 mL, more preferably 0.5 to 5 seconds / 100 mL. possible.
The air permeability is measured according to JIS P8117 using a Gurley standard type densometer (B type).

[Undercoat layer]
The support in the technology disclosed herein may have an undercoat layer between the first surface of the paper substrate and the pressure-sensitive adhesive layer. The undercoat layer can be, for example, a primer layer provided for the purpose of improving the adhesion between the first surface of the support and the pressure-sensitive adhesive layer. Such an undercoat layer (for example, primer layer) is preferably provided so as to constitute the first surface of the support. A known material can be used to form such an undercoat layer. For example, resins such as acrylic resins, rubber polymers, urethane polymers, and epoxy resins can be used. The basis weight of the undercoat layer is typically 1 to 15 g / m ² , preferably ^{2 to} 10 g / m ² , for example 3 to 6 g / m ² .

[Back treatment layer]
The said support body may have the back surface treatment layer which comprises the surface of the 2nd surface side (opposite side of an adhesive layer) of a paper base material. The said back surface treatment layer can be used in order to adjust the back surface peeling strength (peeling strength with respect to the self back surface) of a masking tape, for example. For the formation of the back treatment layer, for example, a known release treatment agent such as a long-chain alkyl release agent or a silicone release agent can be used. The basis weight of the back treatment layer is typically 0.01 to ² g / m ² , preferably 0.05 to 1 g / m ² .

[Backsize layer]
The said support body may have a backsize layer in the 2nd surface side (opposite side to an adhesive layer) of a paper base material. A known material can be used as the back size agent used for forming the back size layer. For example, vinyl acetate resin, acrylic resin, styrene butadiene rubber (SBR), polyester resin, melamine resin, polyamide resin, urea formaldehyde resin, or the like can be used. The basis weight of the backsize layer is typically 1 to 20 g / m ² , preferably ² to 17 g / m ² , more preferably 5 to 15 g / m ² , for example 7 to 11 g / m ^2. . In addition, in the support body including the back treatment layer, it is preferable to arrange a backsize layer between the back treatment layer and the paper substrate.

<Adhesive layer>
The masking tape disclosed here has an adhesive layer containing a rubber-based polymer and an acrylic polymer on the first surface of the paper substrate. Such a pressure-sensitive adhesive layer can be suitably formed using, for example, a pressure-sensitive adhesive composition containing a corresponding rubber polymer and acrylic polymer. The form of the pressure-sensitive adhesive composition is not particularly limited, and examples thereof include a solvent type, a water dispersion type (typically an aqueous emulsion type), an aqueous solution type, an active energy ray curable type (for example, an ultraviolet curable type), and a hot melt type. It can be in various forms. From the viewpoint of reducing environmental burdens, it is preferable to use a water-dispersed pressure-sensitive adhesive composition. Hereinafter, although the component which may be contained in an adhesive layer is demonstrated by making into a main example the case where the said adhesive composition is a water dispersion type, it is not the intention which limits this invention.

[Rubber polymer]
The rubber-based polymer may be a known rubber-based polymer that can be used as a constituent component of a rubber-based pressure-sensitive adhesive such as a natural rubber-based pressure-sensitive adhesive or a synthetic rubber-based pressure-sensitive adhesive. The concept of natural rubber here includes non-modified natural rubber, depolymerized natural rubber, natural rubber obtained by graft-modifying these natural rubber with (meth) acrylic acid alkyl ester, acrylic acid, and the like. , Modified natural rubber such as natural rubber modified with a carboxyl group-containing monomer such as methacrylic acid or itaconic acid. Specific examples of the synthetic rubber include polyisoprene, polybutadiene, polyisobutylene, butyl rubber, styrene-butadiene-styrene block copolymer, styrene-ethylenebutylene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene. -Styrene-type elastomers, such as an ethylene butylene random copolymer, etc. are mentioned. Other examples of the rubber-based polymer include ethylene propylene rubber, propylene butene rubber, and ethylene propylene butene rubber. These can be used alone or in combination of two or more. Of these, preferred rubber-based polymers include natural rubber and isoprene rubber. Natural rubber (which may be depolymerized natural rubber) is particularly preferred.

  Such a rubber-based polymer is typically a pressure-sensitive adhesive composition (preferably a water-dispersed pressure-sensitive adhesive composition) for forming the pressure-sensitive adhesive layer in the form of an aqueous dispersion in which the rubber-based polymer is dispersed in water. It can be preferably used as a constituent of the product. Hereinafter, the aqueous dispersion of rubber polymer is also referred to as “rubber latex”.

  Examples of the rubber latex include natural rubber latex and synthetic rubber latex. The natural rubber latex may be an aqueous dispersion of modified natural rubber obtained by grafting (meth) acrylic acid alkyl ester or the like to natural rubber. Synthetic rubber latex is an aqueous dispersion of synthetic polymer. Examples of the synthetic polymer include polyisoprene, styrene butadiene rubber (SBR), styrene-butadiene-vinyl pyridine polymer, polybutadiene polymer, methyl methacrylate-butadiene copolymer, acrylonitrile-butadiene polymer ( NBR), polychloroprene (CR) and the like.

  A commercially available rubber latex can be used. For example, as styrene butadiene rubber latex, manufactured by Nippon Zeon Co., Ltd. (Nipol series), manufactured by JSR Co., Ltd., manufactured by Asahi Kasei Latex Co., Ltd., manufactured by DIC Corporation (Lackstar series), manufactured by Nippon A & L Co., Ltd. (Narustar series) and the like. Examples of the styrene-butadiene-vinylpyridine latex include products such as those manufactured by Nippon Zeon (Nipol series) and those manufactured by Nippon A & L (pilatex series). Examples of the polybutadiene latex include products made by Nippon Zeon Co., Ltd. (Nipol series). Examples of the methyl methacrylate-butadiene latex include products manufactured by Japan A & L Co., Ltd. (Nalstar series). Examples of the acrylonitrile-butadiene latex include products manufactured by Nippon Zeon Co., Ltd. (Nipol series), manufactured by Nippon A & L Co., Ltd. (Siatex series), and manufactured by DIC Corporation (Lackstar series). Examples of the polychloroprene latex include products made by Showa Denko KK (Showpren series), Tosoh Corporation (Skyprene series), and the like. Examples of natural rubber latex include products manufactured by Tile Restex.

[Acrylic polymer]
As the acrylic polymer, for example, a polymer of a monomer raw material that includes alkyl (meth) acrylate as a main monomer and can further include a submonomer copolymerizable with the main monomer is preferable. Here, the main monomer means a component occupying more than 50% by weight of the monomer composition in the monomer raw material.

As the alkyl (meth) acrylate, for example, a compound represented by the following formula (1) can be preferably used.
CH ₂ = C (R ¹ ) COOR ² (1)
Here, R ¹ in the above formula (1) is a hydrogen atom or a methyl group. R ² is a chain alkyl group having 1 to 20 carbon atoms (hereinafter, such a range of the number of carbon atoms may be represented as “C _1-20 ”). From the viewpoint of the storage elastic modulus and the like of the pressure-sensitive adhesive, an alkyl (meth) acrylate in which R ² is a C _1-14 chain alkyl group is preferable, and R ² is an alkyl (meta) that is a C _1-10 chain alkyl group. ) Acrylate is more preferable, and alkyl (meth) acrylate in which R ² is a butyl group or a 2-ethylhexyl group is particularly preferable.

Examples of the alkyl (meth) acrylate in which R ² is a C _1-20 chain 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, 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, 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, And eicosyl (meth) acrylate. These alkyl (meth) acrylates can be used alone or in combination of two or more. Particularly preferred alkyl (meth) acrylates include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA).

A submonomer having copolymerizability with the main monomer, alkyl (meth) acrylate, can be useful for introducing a crosslinking point into the acrylic polymer or increasing the cohesive strength of the acrylic polymer. As the submonomer, for example, the following functional group-containing monomer components can be used singly or in combination of two or more.
Carboxyl group-containing monomers: ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as maleic acid, itaconic acid and citraconic acid and anhydrides thereof (maleic anhydride, anhydrous) Itaconic acid).
Hydroxyl group-containing monomer: For example, hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate; Unsaturated alcohols such as vinyl alcohol and allyl alcohol.
Amide group-containing monomer: 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, N-butoxymethyl (meth) acrylamide.
Amino group-containing monomer: for example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate.
Monomers having an epoxy group: for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether.
Cyano group-containing monomer: for example, acrylonitrile, methacrylonitrile.
Keto group-containing monomers: for example, diacetone (meth) acrylamide, diacetone (meth) acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetoacetate, vinyl acetoacetate.
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinyl Pyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N- (meth) acryloylmorpholine.
Alkoxysilyl group-containing monomer: For example, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxy Propylmethyldiethoxysilane.

  The amount of the submonomer may be appropriately selected so as to achieve a desired cohesive force, and is not particularly limited. Usually, from the viewpoint of achieving a good balance between cohesive force and adhesiveness, the amount of the secondary monomer is suitably 20% by weight or less, preferably 15% by weight or less, preferably 10% by weight or less of the monomer composition of the acrylic polymer. Is more preferable.

Although it does not specifically limit, When using a carboxyl group-containing monomer as said submonomer, the content can be 0.1-10 weight% of all the monomer raw materials, for example, and usually 0.2-8 It is appropriate to set the weight% (typically 0.5 to 5% by weight).
Although it does not specifically limit, When using a hydroxyl-containing monomer as said submonomer, the content can be made into 0.001 to 10 weight% of all the monomer raw materials, for example, and usually 0.01 to 5 weight % (Typically 0.02 to 2% by weight).

  For the purpose of increasing the cohesive strength of the acrylic polymer, other copolymer components other than the above-mentioned secondary monomer can be used. Examples of such copolymer components include vinyl ester monomers such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), vinyltoluene; cyclohexyl (meth) acrylate, cyclopentyl ( Cycloalkyl (meth) acrylates such as meth) acrylate and isobornyl (meth) acrylate; aryl (meth) acrylate (eg phenyl (meth) acrylate), aryloxyalkyl (meth) acrylate (eg phenoxyethyl (meth) acrylate), aryl Aromatic ring-containing (meth) acrylates such as alkyl (meth) acrylates (eg benzyl (meth) acrylate); olefins such as ethylene, propylene, isoprene, butadiene and isobutylene Monomers; Chlorine-containing monomers such as vinyl chloride and vinylidene chloride; Isocyanate group-containing monomers such as 2- (meth) acryloyloxyethyl isocyanate; Alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; And vinyl ether monomers such as vinyl ether and ethyl vinyl ether. The amount of such other copolymerization component is not particularly limited as long as it is appropriately selected depending on the purpose and application. For example, it is preferably 10% by weight or less of the monomer composition of the acrylic polymer.

  The copolymer composition of the acrylic polymer is suitably designed so that the glass transition temperature (Tg) of the polymer is -15 ° C or lower (typically -75 ° C or higher and -15 ° C or lower). The temperature is preferably −25 ° C. or less (for example, −70 ° C. or more and −25 ° C. or less), more preferably −40 ° C. or less (for example, −70 ° C. or more and −40 ° C. or less). The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (that is, the type and amount ratio of monomers used for the synthesis of the polymer).

  Here, the Tg of the acrylic polymer refers to a fox based on the Tg of the homopolymer (homopolymer) of each monomer constituting the polymer and the weight fraction (copolymerization ratio based on weight) of the monomer. The value obtained from the formula.

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
Vinyl acetate 32 ° C
Acrylic acid 106 ℃
Methacrylic acid 228 ° 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 the above document, values obtained by the following measurement method are used (see Japanese Patent Application Publication No. 2007-51271). Specifically, a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser is charged with 100 parts by weight of monomer, 0.2 part by weight of azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent. 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.

Such an acrylic polymer is typically a pressure-sensitive adhesive composition (preferably a water-dispersed pressure-sensitive adhesive composition) for forming the pressure-sensitive adhesive layer in the form of an aqueous dispersion in which the acrylic polymer is dispersed in water. It can be preferably used as a constituent of the product.
The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as synthetic methods for acrylic polymers, such as solution polymerization method, emulsion polymerization method, bulk polymerization method, suspension polymerization method, photopolymerization method, etc. Can be adopted as appropriate. For example, an emulsion polymerization method can be preferably used.

  As a monomer supply method when emulsion polymerization is performed, a batch charging method, a continuous supply (dropping) method, a divided supply (dropping) method, or the like that supplies all monomer raw materials at one time can be appropriately employed. The monomer raw material may be added dropwise in the form of an aqueous emulsion. The polymerization conditions are not particularly limited. For example, the polymerization temperature can be about 20 ° C. to 100 ° C. (typically 40 ° C. to 90 ° C.).

  The initiator used for the polymerization can be appropriately selected from conventionally known polymerization initiators. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2, 2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate, 2,2′-azobis (N, N Azo initiators such as' -dimethyleneisobutylamidine), 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, for example, persulfate such as potassium persulfate and ammonium persulfate Salt initiators, for example, peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide, hydrogen peroxide, for example, substituted ethane initiators such as phenyl substituted ethane, Eg to a carbonyl-based initiators such as aromatic carbonyl compounds, for example, a combination of a persulfate and sodium hydrogen sulfite, redox initiators such as a combination of a peroxide and sodium ascorbate and the like. Such a polymerization initiator can be used individually by 1 type or in combination of 2 or more types.

  The amount of the polymerization initiator used may be a normal amount, for example, 0.005 to 1 part by weight, preferably about 0.01 to 0.8 part by weight based on 100 parts by weight of all monomer components. You can choose from.

  The emulsifier used for the polymerization is not particularly limited, and an emulsifier usually used for emulsion polymerization may be used. For example, sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene Anionic emulsifiers such as sodium alkylsulfosuccinate; nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene polyoxypropylene block polymer, and the like. In addition, radically polymerizable (reactive) emulsifiers (for example, Daiichi Kogyo Seiyaku (for example, Daiichi Kogyo Seiyaku Co., Ltd.)) are introduced into these anionic emulsifiers and nonionic emulsifiers. (Trade name "HS-10") manufactured by Co., Ltd. may be used. Moreover, from the viewpoint of storage stability of the pressure-sensitive adhesive composition, an embodiment in which only an emulsifier having no radical polymerizable functional group is used as the emulsifier can be preferably employed.

  These emulsifiers can be used alone or in combination of two or more. The blending ratio of the emulsifier may be, for example, 0.2 to 10 parts by weight, preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the total amount of the monomer composition.

  A chain transfer agent that adjusts the molecular weight of the acrylic polymer can be used as necessary. As the chain transfer agent, a chain transfer agent usually used for emulsion polymerization is used. Examples thereof include mercaptans such as 1-dodecanethiol, mercaptoacetic acid, 2-mercaptoethanol, 2-ethylhexyl thioglycolate, and 2,3-dimethylcapto-1-propanol. These chain transfer agents are appropriately used alone or in combination. Moreover, the mixture ratio of a chain transfer agent may be 0.001-0.5 weight part with respect to 100 weight part of total amounts of a monomer composition, for example.

The weight average molecular weight of the acrylic polymer (Mw) may be particularly limited without, for example, ¹⁰ × 10 ⁴ ~500 × 10 4 range. Here, the Mw of the acrylic polymer refers to the Mw of the toluene-soluble component (sol component) of the acrylic polymer. Specifically, the Mw of the acrylic polymer refers to a standard polystyrene equivalent value based on GPC (gel permeation chromatography) obtained by the method described in Examples described later. From the viewpoint of peel strength, the Mw of the acrylic polymer is preferably 150 × 10 ⁴ or less, and more preferably 100 × 10 ⁴ or less. Further, from the viewpoints of holding power (cohesive force) and non-glue residue, the acrylic polymer Mw is preferably 20 × 10 ⁴ or more, more preferably 30 × 10 ⁴ or more (for example, 40 × 10 ⁴ or more). obtain.

[Blend ratio]
The pressure-sensitive adhesive layer in the technology disclosed herein may contain the rubber-based polymer and the acrylic polymer as described above in an arbitrary weight ratio (that is, a blend ratio based on weight). In the pressure-sensitive adhesive layer according to a preferred embodiment, the weight ratio of rubber polymer to acrylic polymer (hereinafter also referred to as “rubber / acrylic ratio”) is in the range of 40/60 to 95/5. Since the pressure-sensitive adhesive layer having such a composition has a rubber / acrylic ratio in an appropriate range, it can hardly change the appearance of the mask object and can stably exhibit an appropriate peel strength for the mask object. Therefore, it is preferable. This is particularly significant in a masking tape that can be attached to a coating film (for example, a urethane coating film, a nitrocellulose coating film, etc.) or a metal.

  The rubber / acrylic ratio is usually suitably more than 50/50, preferably more than 60/40, more preferably more than 65/35, still more preferably more than 75/25, and particularly preferably 80/20. It is super (for example, over 85/15). When the rubber / acrylic ratio is increased, the cohesive force of the pressure-sensitive adhesive layer tends to be further improved. This is preferable from the viewpoint of improving non-glue residue. Further, when the rubber / acryl ratio is increased, the appearance of the mask object tends to hardly change. The upper limit of the rubber / acryl ratio can be less than 95/5, for example, 93/7 or less.

[Tackifying resin]
In a preferred embodiment, the pressure-sensitive adhesive layer can contain a tackifier resin. As tackifying resin, well-known tackifying resin which can be used for an adhesive can be used. By using the tackifying resin, the peel strength with respect to the mask object can be adjusted to an appropriate range.

  Examples of tackifying resins include unmodified rosin (gum rosin, wood rosin, tall oil rosin, etc.), stabilized rosin (for example, stabilized rosin obtained by disproportionating or hydrogenating the unmodified rosin), and polymerized rosin (for example, the above-mentioned Rosin multimer, typically dimer), modified rosin (for example, unsaturated acid-modified rosin in which the unmodified rosin is modified with an unsaturated acid such as maleic acid, fumaric acid, (meth) acrylic acid, etc.) Rosin ester resins such as rosin esters, stabilized rosin esters (hydrogenated rosin esters, disproportionated rosin esters, etc.), polymerized rosin esters, etc .; rosin phenol resins such as rosin-modified phenol resins; coumarone Inden resin, hydrogenated coumarone inden resin, phenol modified coumarone inden resin, epoxy modified coumarone inden tree Coumarone indene resins such as α-pinene resins, β-pinene resins, polyterpene resins, hydrogenated terpene resins, aromatic modified terpene resins, terpene phenol resins, etc .; aliphatic petroleum resins, aromatic resins Petroleum resins such as petroleum resins, aromatic modified aliphatic petroleum resins, copolymerized petroleum resins, alicyclic petroleum resins, and their hydrides (hydrogenated petroleum resins). These can be used alone or in combination of two or more. Preferred tackifying resins include rosin ester resins (stabilized rosin esters, polymerized rosin esters, etc.), rosin phenol resins and petroleum resins.

  In a preferred embodiment, two or more kinds of tackifying resins can be used in combination. In an embodiment in which two types of tackifying resins A and B are used in combination, the weight ratio of these tackifying resins is not particularly limited. The amount of tackifying resin A in the total amount of tackifying resin A and tackifying resin B is typically 10% by weight or more, preferably 25% by weight or more, more preferably 30% by weight or more (eg 50% by weight). %)). The proportion of the tackifying resin A is typically 95% by weight or less of the total amount of the tackifying resin A and the tackifying resin B, preferably 90% by weight or less, more preferably 80% by weight or less (for example, 70 % By weight or less). The tackifier resin A may be selected from rosin resins, rosin ester resins, rosin phenol resins (for example, rosin modified phenol resins) and terpene resins. The tackifying resin B can be selected from, for example, petroleum-based resins (for example, hydrogenated petroleum resins).

  The amount of tackifying resin used is not particularly limited. In one embodiment of the technology disclosed herein, the amount of the tackifying resin used is, for example, 50 parts by weight or less (typically less than 50 parts by weight) with respect to 100 parts by weight of the total amount of the rubber-based polymer and the acrylic polymer. ). From the standpoint of non-glue residue, etc., it is usually appropriate to use the tackifying resin in an amount of 30 parts by weight or less, preferably 20 parts by weight or less, based on the total amount of 100 parts by weight. By setting the amount of the tackifying resin used to less than 20 parts by weight (for example, 18 parts by weight or less) relative to 100 parts by weight of the total amount, a better result can be realized. In a preferred embodiment, the amount of the tackifying resin used relative to 100 parts by weight of the total amount can be 15 parts by weight or less, and may be 10 parts by weight or less.

  In another embodiment of the technology disclosed herein, the amount of the tackifying resin used is, for example, 100 parts by weight or less (typically 100 parts by weight with respect to 100 parts by weight of the total amount of the rubber-based polymer and the acrylic polymer). Less than part by weight). From the viewpoint of pasting workability and the like, it is appropriate that the amount of the tackifying resin used is usually 80 parts by weight or less with respect to 100 parts by weight of the total amount of rubber polymer and acrylic polymer, and less than 70 parts by weight. Preferably, the amount is less than 60 parts by weight (for example, 55 parts by weight or less).

  The minimum of the usage-amount of tackifying resin is not specifically limited. From the viewpoint of suitably exhibiting the effect of the use of the tackifying resin, it is usually appropriate that the amount of the tackifying resin used is 1 part by weight or more with respect to 100 parts by weight of the total amount of the rubber polymer and the acrylic polymer. The amount is preferably 3 parts by weight or more, and more preferably 5 parts by weight or more.

  In one embodiment, the use amount of the tackifying resin with respect to 100 parts by weight of the total amount of the rubber polymer and the acrylic polymer can be 10 parts by weight or more, may be 25 parts by weight or more, and is 35 parts by weight or more (for example, 40 parts by weight or more). By increasing the amount of the tackifying resin used, effects such as improvement in peel strength and reduction in the peel strength change rate tend to be exhibited better.

  The softening point of the tackifying resin to be used is not particularly limited. From the viewpoint of non-glue residue and cohesive strength, a tackifying resin having a high softening point can be preferably used. A tackifying resin having a high softening point is also preferable from the viewpoint of suppressing the change in the appearance of the mask object and the change in the peel strength over time. For example, a tackifying resin having a softening point of 120 ° C. or higher is preferable, and a softening point of 130 ° C. or higher is more preferable. In a preferred embodiment, a tackifier resin having a temperature of 140 ° C. or higher (eg, 145 ° C. or higher) can be used. The kind of the tackifying resin having a high softening point is not particularly limited. For example, one kind of the above-described tackifying resin can be used alone or two or more kinds can be used in combination. Preferable examples include rosin ester resins (for example, polymerized rosin esters) and rosin phenol resins.

  The pressure-sensitive adhesive layer disclosed herein includes a combination of a tackifying resin having a high softening point (for example, a tackifying resin having a softening point of 120 ° C. or higher) and a tackifying resin having a lower softening point as described above. You may go out. As the tackifying resin having a low softening point, those having a softening point of 110 ° C. or lower (preferably 100 ° C. or lower, for example, 80 ° C. or lower) can be used. The kind of tackifying resin having a low softening point is not particularly limited. For example, one kind of the above-described tackifying resin can be used alone or in combination of two or more kinds. Preferable examples include petroleum resins, stabilized rosins and stabilized rosin esters.

  In an embodiment in which a tackifying resin C having a softening point of 120 ° C. or higher and a tackifying resin D having a softening point of less than 120 ° C. (for example, 110 ° C. or lower) are used in combination, the ratio of the amount of the tackifying resin used ( The weight ratio is not particularly limited. The proportion of the tackifying resin C in the total amount of the tackifying resin C and the tackifying resin D is typically 10% by weight or more, preferably 25% by weight or more, more preferably 30% by weight or more (for example, 50% by weight). %)). The proportion of the tackifying resin C is typically 95% by weight or less, preferably 90% by weight or less, more preferably 80% by weight or less (for example, 70% by weight or less). The tackifier resin C may be selected from rosin ester resins, rosin phenol resins (for example, rosin-modified phenol resins) and terpene resins (for example, terpene phenol resins). The tackifying resin D can be selected from petroleum-based resins (eg, hydrogenated petroleum resins) and stabilized rosin esters.

  In addition, the softening point of tackifying resin can be measured based on the softening point test method (ring ball method) prescribed | regulated to JISK2207.

[Crosslinking agent]
In the technology disclosed herein, the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer may contain a crosslinking agent as necessary. The type of the crosslinking agent is not particularly limited, and conventionally known crosslinking agents such as carbodiimide crosslinking agents, hydrazine crosslinking agents, epoxy crosslinking agents, isocyanate crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents. It can be appropriately selected from a crosslinking agent, a silane coupling agent and the like. Such crosslinking agents can be used singly or in combination of two or more.
The usage-amount of a crosslinking agent is not specifically limited, It can set suitably so that the adhesive which shows a desired characteristic may be formed. For example, the content of the crosslinking agent with respect to 100 parts by weight of the polymer component (the total amount of the rubber polymer and acrylic polymer) can be 10 parts by weight or less, preferably 0.01 to 10 parts by weight, more preferably 0. .015 to 5 parts by weight.

  An example of a preferable crosslinking agent is an epoxy-based crosslinking agent. Examples of the epoxy-based crosslinking agent include N, N, N ′, N′-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1, 6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, penta Erythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl In addition to ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether, Examples thereof include epoxy resins having two or more. Moreover, as an epoxy-type crosslinking agent, commercial items, such as the brand name "Tetrad C" by Mitsubishi Gas Chemical Co., Ltd. and the brand name "E50-C" by Soken Chemical Co., Ltd., can also be used, for example.

  The amount of the epoxy crosslinking agent used is not particularly limited. The content of the epoxy crosslinking agent with respect to 100 parts by weight of the polymer component is typically 5 parts by weight or less, preferably 1 part by weight or less, more preferably 0.5 parts by weight or less (for example, 0.1 parts by weight or less). can do. The content of the epoxy crosslinking agent with respect to 100 parts by weight of the polymer component is typically 0.005 parts by weight or more, and preferably 0.01 parts by weight or more (for example, 0.015 parts by weight or more).

  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, trimethylolpropane / tolylene diisocyanate trimer adduct (product name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate trimer adduct (Nippon Polyurethane Industry Co., Ltd.) And an isocyanate adduct such as isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name “Coronate HX”). In the water-dispersed pressure-sensitive adhesive composition, it is preferable to use an isocyanate crosslinking agent that can be dissolved or dispersed in water. For example, a water-soluble, water-dispersible or self-emulsifying type isocyanate crosslinking agent can be preferably employed. A so-called blocked isocyanate type isocyanate crosslinking agent in which an isocyanate group is blocked can be preferably used. An isocyanate type crosslinking agent can be used individually by 1 type or in combination of 2 or more types.

  The amount of the isocyanate crosslinking agent used is not particularly limited. For example, the content of the isocyanate-based crosslinking agent with respect to 100 parts by weight of the polymer component is typically 15 parts by weight or less, preferably 10 parts by weight or less, more preferably 7 parts by weight or less. The content of the isocyanate-based crosslinking agent with respect to 100 parts by weight of the polymer component is typically 0.1 parts by weight or more, preferably 0.5 parts by weight or more (for example, 1.0 parts by weight or more).

  A carbodiimide-based crosslinking agent is a compound having a carbodiimide group. The carbodiimide group is a functional group in which one hydrogen atom is extracted from carbodiimide (HN = C = NH) (-N = C = NH), or a functional group in which two hydrogen atoms are extracted (-N = C = NH). N-). As the carbodiimide-based crosslinking agent, for example, a low molecular compound or a high molecular compound having two or more carbodiimide groups can be used. Examples of commercially available carbodiimide crosslinking agents include Carbodilite V series (aqueous solution type) such as “Carbodilite V-02”, “Carbodilite V-02-L2”, and “Carbodilite V-04” manufactured by Nisshinbo Co., Ltd. Carbodilite series such as Carbodilite E-01 (water dispersion type) such as Carbodilite E-01, Carbodilite E-02, and Carbodilite E-04.

  The amount of carbodiimide-based crosslinking agent used is not particularly limited. The content of the carbodiimide-based crosslinking agent with respect to 100 parts by weight of the polymer component is typically 15 parts by weight or less, preferably 10 parts by weight or less, more preferably 7 parts by weight or less. The content of the carbodiimide-based crosslinking agent with respect to 100 parts by weight of the polymer component is typically 0.1 parts by weight or more, preferably 0.5 parts by weight or more (for example, 1.0 parts by weight or more).

[Other ingredients]
The pressure-sensitive adhesive composition may be a leveling agent, a crosslinking aid, a plasticizer, a softener, a filler, an antistatic agent, an anti-aging agent, an ultraviolet absorber, an antioxidant, a light stabilizer, etc., if necessary. You may contain various additives common in the field | area of an adhesive composition. About such various additives, conventionally well-known things can be used by a conventional method, and since it does not characterize this invention in particular, detailed description is abbreviate | omitted.

[Formation of adhesive layer]
A pressure-sensitive adhesive composition containing a rubber-based polymer and an acrylic polymer can typically be prepared by mixing these polymers with other components (such as a tackifying resin) that can be used as necessary. it can. In the case of a water-dispersed pressure-sensitive adhesive composition, it can be prepared by mixing an aqueous dispersion of rubber polymer particles (rubber latex) and an aqueous dispersion of acrylic polymer particles (acrylic polymer emulsion). preferable. This makes it possible to easily prepare a pressure-sensitive adhesive composition in which a rubber polymer and an acrylic polymer are well blended at a desired ratio. In this case, the tackifying resin that can be optionally used is also preferably mixed in the form of a water-dispersed tackifying resin in which the tackifying resin is dispersed in water.

As a method of forming a pressure-sensitive adhesive layer using such a pressure-sensitive adhesive composition, various conventionally known methods can be appropriately applied. For example, a method (direct method) of forming a pressure-sensitive adhesive layer by directly applying (typically applying) the pressure-sensitive adhesive composition to the first surface of the support and drying it can be preferably employed. Further, the pressure-sensitive adhesive composition is applied to a surface having good releasability (for example, the surface of a release liner, the back surface of a support subjected to a release treatment, etc.) and dried to form a pressure-sensitive adhesive layer on the surface. You may employ | adopt the method (transfer method) which transcribe | transfers an adhesive layer to the 1st surface of a support body.
The masking tape disclosed here can be manufactured according to the manufacturing method of a normal adhesive tape. For example, an undercoat treatment is performed on the first surface of the paper substrate, a backsize treatment and / or a back surface treatment is performed on the second surface to produce a support, and an adhesive is applied to the undercoat treatment surface (first surface) of the support. It can be produced by forming a layer and cutting it into an appropriate size or width as required.
Application of the pressure-sensitive adhesive composition can be performed using a known or conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater. . The pressure-sensitive adhesive layer is typically formed continuously, but may be formed in a regular or random pattern such as a dot or stripe depending on the purpose and application.

Although not particularly limited, the thickness of the pressure-sensitive adhesive layer may be, for example, 3 μm or more, usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and further preferably 20 μm or more. When the thickness of the pressure-sensitive adhesive layer is increased, the smoothness of the pressure-sensitive adhesive surface (the surface to be adhered to the adherend, that is, the mask object) tends to be improved. This is particularly effective when porous paper such as crepe paper or Japanese paper is used as the paper substrate. When the smoothness of the adhesive surface is improved, the adhesion to the adherend is improved, and it is preferable because the paint or the like hardly enters from the outer edge of the masking tape into the pasting range. Good smoothness of the adhesive surface is preferable from the viewpoint of non-glue residue and peel strength stability. In a preferable embodiment (for example, an embodiment in which the paper substrate is crepe paper), the thickness of the pressure-sensitive adhesive layer may be 25 μm or more, or 30 μm or more.
The upper limit of the thickness of an adhesive layer is not specifically limited, For example, it can be 200 micrometers or less. The thickness of the pressure-sensitive adhesive layer is usually 150 μm or less, preferably 100 μm or less, more preferably 70 μm or less, and further preferably 50 μm or less (for example, 40 μm or less).
Note that the pressure-sensitive adhesive layer in the technology disclosed herein may have a single-layer structure composed of only one layer or a multilayer structure including two or more layers.

  Although it does not specifically limit, the gel fraction of the adhesive which comprises an adhesive layer may be about 10 to 90% on a weight basis, for example. From the viewpoint of suitably balancing the cohesive force and peel strength, the gel fraction is preferably 20 to 85%, and more preferably 25 to 80%. The gel fraction of the pressure-sensitive adhesive can be adjusted, for example, by selecting the composition and molecular weight of the acrylic polymer, the presence / absence of the use of the crosslinking agent, the type thereof, and the amount used. In addition, the gel fraction of an adhesive is measured with the following method. The upper limit of the gel fraction is 100% by weight in principle.

[Gel fraction]
The pressure-sensitive adhesive composition is dried at 130 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of about 35 μm. A pressure-sensitive adhesive sample is collected from the pressure-sensitive adhesive layer, and the gel fraction is measured.
Specifically, about 0.1 g of a pressure-sensitive adhesive sample (weight Wg ₁ ) is wrapped in a purse-like shape with a porous polytetrafluoroethylene membrane (weight Wg ₂ ) having an average pore diameter of 0.2 μm, and the mouth is octopus yarn (weight Wg) ₃ ) Bind with. As the porous polytetrafluoroethylene membrane, a trade name “Nitoflon (registered trademark) NTF1122” (Nitto Denko Corporation, average pore diameter 0.2 μm, porosity 75%, thickness 85 μm) or its equivalent is used. This wrap is immersed in 50 mL of toluene and kept at room temperature (typically 23 ° C.) for 7 days to elute only the sol component in the pressure-sensitive adhesive layer out of the membrane. Next, the packet is taken out and wiped off the ethyl acetate adhering to the outer surface, and then the packet is dried at 130 ° C. for 2 hours, and the weight (Wg ₄ ) of the packet is measured. By substituting each value into the following equation, it is possible to calculate the gel fraction F _G of the pressure-sensitive adhesive.
Gel fraction F _G (%) = [(Wg ₄ −Wg ₂ −Wg ₃ ) / Wg ₁ ] × 100

<Masking tape>
The masking tape disclosed herein may have a total thickness of 1 mm or less (eg, 500 μm or less). Here, the total thickness of the masking tape refers to the total thickness of the support and the pressure-sensitive adhesive layer. The lower limit of the total thickness of the masking tape can be, for example, 30 μm or more, and is usually preferably 50 μm or more.

The more preferable range of the total thickness of the masking tape may vary depending on the type of paper substrate.
For example, when the paper substrate is crepe paper, the total thickness is, for example, 1 mm or less, usually 500 μm or less, preferably 300 μm or less, more preferably 200 μm or less. The total thickness may be, for example, 50 μm or more, usually 70 μm or more, preferably 100 μm or more, more preferably 120 μm or more.
For example, when the paper substrate is Japanese paper, the total thickness is, for example, 500 μm or less, usually 300 μm or less, preferably 200 μm or less, more preferably 150 μm or less. The total thickness can be, for example, 30 μm or more, usually 50 μm or more, preferably 60 μm or more, more preferably 70 μm or more.

  The width of the masking tape is not particularly limited, and can be appropriately set according to the purpose and application. In a preferred embodiment, the width of the masking tape can be, for example, 500 mm or less, usually 300 mm or less, preferably 200 mm or less. The width of the masking tape may be 100 mm or less, or 70 mm or less. Further, from the viewpoint of easiness of the pasting operation and the peeling operation, the width of the masking tape can be, for example, 5 mm or more, usually 10 mm or more (typically 15 mm or more). The width of the masking tape may be 20 mm or more, or 30 mm or more.

  An example of a cross-sectional structure of the masking tape disclosed herein is schematically shown in FIG. The masking tape 1 includes a support 10 and any pressure-sensitive adhesive layer 20 disclosed herein. The support 10 includes a paper substrate 12, an undercoat layer 14 on the first surface 12A, and a backside layer 16 on the second surface 12B of the paper substrate 12. The surface of the undercoat layer 14 corresponds to the first surface 10 </ b> A of the support 10, and the surface of the back layer 16 corresponds to the back surface 10 </ b> B of the support 10. An adhesive layer 20 is disposed on the first surface 10 </ b> A of the support 10.

  As shown in FIG. 1, the masking tape according to a preferred embodiment typically has a surface (adhesive surface) 20 </ b> A of the pressure-sensitive adhesive layer 20 in contact with the back surface 10 </ b> B of the support 10, typically around the core 30. It may be in the form of a masking tape roll 100 wound in a spiral. Such a masking tape roll 100 is obtained by, for example, attaching one end of the masking tape 1 to an adherend, and rewinding the roll 100 by applying tension between the attached portion and the roll 100 ( That is, the present invention can be preferably applied to a usage mode in which the masking tape 1 is continuously applied to a long range (by feeding the tape 1 from the roll 100).

As a modification, the masking tape 1 shown in FIG. 1 is disposed on the masking tape 1 and the surface (adhesive surface) 20A of the adhesive layer 20, and at least the surface (front surface) on the adhesive layer 20A side is a release surface. It may be in the form of a masking tape roll in which release liners (not shown) are overlapped and these are wound around the core 30.
Moreover, the masking tape disclosed here may be a sheet shape or a tape shape that is not wound, and the adhesive surface may be protected by a release liner.

  A conventional release paper or the like can be used as the release liner, and is not particularly limited. For example, a release liner having a release treatment layer on the surface of a liner substrate such as a plastic film or paper, and a release made of a low adhesive material such as a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin (polyethylene, polypropylene, etc.) A liner or the like can be used. The release treatment layer may be formed by surface-treating the liner base material with various release treatment agents such as silicone-based, long-chain alkyl-based, fluorine-based, and molybdenum sulfide.

  The masking tape disclosed herein is a masking tape that does not have a release liner (for example, a mask mask in a roll form, from the viewpoint of workability when continuously sticking to a large mask object for a long time and resource saving) That is, it is preferably in the form of a masking tape roll).

  The length of the masking tape contained in the masking tape roll is not particularly limited, and can be, for example, 5 m or longer, and is preferably 10 m or longer. The large length of the masking tape contained in one roll of masking tape roll is particularly advantageous in applications in which the masking tape is continuously applied to the adherend for a long time. On the other hand, it is preferable that the masking tape roll is not too heavy from the viewpoint of reducing the burden on the worker who performs the pasting operation. From this viewpoint, the length of the masking tape included in one roll of masking tape roll can be, for example, 50 m or less, and is preferably 30 m or less.

The masking tape disclosed here preferably has a tensile strength in the flow direction (MD) of 30 N / 18 mm or more, and more preferably 50 N / 18 mm or more. When MD tensile strength is high, when it peels off the masking tape after use from a mask target object, it will become difficult to tear in the middle and it exists in the tendency for peeling workability | operativity to improve. Further, since the masking tape can be applied with sufficient tension (that is, in a stretched state without slack), it is preferable from the viewpoint of application workability and application accuracy. This is particularly advantageous in a masking tape that is supposed to be used for a long continuous application. The upper limit of MD tensile strength is not specifically limited, For example, it can be set to 150 N / 18mm or less, and it is suitable that it is normally set to 120 N / 18mm or less.
The tensile strength in the width direction (TD) of the masking tape is not particularly limited. From the viewpoint of better preventing tearing during peeling, the TD tensile strength can be set to, for example, 10 to 100 N / 18 mm, and usually 15 to 80 N / 18 mm.
The tensile strength is measured in accordance with the “tensile strength” measuring method described in JIS Z0237: 2009.

In the masking tape disclosed herein, the elongation at break of TD is preferably 15.0% or less, and more preferably 12.5% or less, from the viewpoint of suppressing cupping. The cupping refers to a phenomenon in which the masking tape is bent in the width direction (typically, with the adhesive surface facing inward). Suppressing cupping is particularly significant in a masking tape that is supposed to be used for a long continuous application. The lower limit of elongation at break of TD is not particularly limited, but is usually preferably 2.0% or more and more preferably 4.0% or more from the viewpoint of surface shape followability and the like.
The elongation at the time of MD fracture of the masking tape is not particularly limited, and can be, for example, 1.5 to 20.0%, and usually 3.0 to 15.0%.
The elongation at break is measured in accordance with the “elongation” measurement method described in JIS Z0237: 2009.

  The masking tape according to a preferred embodiment preferably has a back surface peel strength of 0.7 N / 18 mm or more, and more preferably 1.0 N / 18 mm or more, from the viewpoints of overlayability and pasting workability. As shown in FIG. 1, in the masking tape roll wound with the adhesive surface in contact with the back surface (especially a masking tape roll that is continuously applied for a long time), from the viewpoint of application workability, etc., the masking tape roll It is preferable to have the above-mentioned back surface peel strength that does not unwind due to its own weight. Therefore, it is particularly meaningful to have the above-mentioned back surface peel strength. Although the upper limit of the back surface peel strength is not particularly limited, it is usually suitably set to 10.0 N / 18 mm or less. The back surface peel strength is measured by using, as an adherend, a material obtained by attaching a masking tape to the surface of a SUS plate in the SUS peel strength measurement described in Examples described later.

  The masking tape according to a preferred embodiment has a SUS peel strength of 1.0 N / 18 mm or more, more preferably 1.5 N / 18 mm or more, still more preferably 2.0 N / measured by the method described in the examples described later. 18 mm or more. A masking tape exhibiting such characteristics has good workability for attaching to a mask object having an unpainted metal surface, for example. The upper limit of SUS peel strength is not particularly limited. For example, 10.0 N / 18 mm or less, usually 7.0 N / 18 mm or less, preferably 5.0 N / 18 mm or less, more preferably 4.0 N / 18 mm from the viewpoint of suppressing changes in the appearance of the mask object and reducing the work load. Hereinafter, it is more preferably 3.5 N / 18 mm or less (for example, 3.0 N / 18 mm or less).

  The masking tape according to another preferred embodiment has a SUS peel strength of 2.5 N / 18 mm or more, more preferably 4.0 N / 18 mm or more, for example, 5.0 N / 18 mm or more. A masking tape exhibiting such characteristics has good adhesion to a mask object having an unpainted metal surface, for example. The upper limit of the SUS peel strength is not particularly limited, but is typically 15.0 N / 18 mm or less, usually 10.0 N / 18 mm or less (for example, 7.0 N / 18 mm) from the viewpoint of suppressing changes in the appearance of the mask object. The following).

  The masking tape according to a preferred embodiment has a peel strength after 2 hours of coating of 0.5 N / 18 mm or more, more preferably 0.7 N / 18 mm or more, more preferably measured by the method described in the examples described later. It is 1.0 N / 18 mm or more. A masking tape exhibiting such properties has good workability for applying to a mask object having a coating film (for example, a urethane coating film, a nitrocellulose coating film, etc.). The upper limit of the peel strength after 2 hours against the coated plate is not particularly limited. For example, 7.0 N / 18 mm or less, usually 5.0 N / 18 mm or less, preferably 4.0 N / 18 mm or less, more preferably 3.0 N / 18 mm, from the viewpoint of suppressing changes in the appearance of the mask object or reducing the work load. Hereinafter, it is more preferably 2.5 N / 18 mm or less (for example, 2.0 N / 18 mm or less).

  A masking tape according to another preferred embodiment has a peel strength of 3.0 N / 18 mm or more, more preferably 5.0 N / 18 mm or more, such as 7.0 N / 18 mm or more, and 8 N / It may be 18 mm or more. A masking tape exhibiting such characteristics has good adhesion to a mask object having a coating film. The upper limit of the peel strength after 2 hours against the coated plate is not particularly limited, but is typically 15.0 N / 18 mm or less, and usually 12.0 N / 18 mm or less, from the viewpoint of suppressing changes in the appearance of the mask object.

  The masking tape according to a preferred embodiment has a peel strength of 0.5 N / 18 mm or more, more preferably 0.7 N / 18 mm or more, more preferably 1 after 1 day against a coated plate measured by the method described in the examples described later. 0.0 N / 18 mm or more. A masking tape exhibiting such characteristics is excellent in performance (surface shape followability) for maintaining a close contact state along the surface shape of a mask object having a coating film (for example, a urethane coating film, a nitrocellulose coating film, etc.). . The upper limit of the peel strength after one day from the coated plate is not particularly limited, and can be, for example, 7.0 N / 18 mm or less. From the viewpoint of suppressing the change in the appearance of the mask object and reducing the work load, it is usually 5.0 N / It is 18 mm or less, preferably 4.0 N / 18 mm, more preferably 3.0 N / 18 mm or less, and further preferably 2.5 N / 18 mm or less (for example, 2.0 N / 18 mm or less).

  A masking tape according to another preferred embodiment has a peel strength of 3.0 N / 18 mm or more, more preferably 5.0 N / 18 mm or more, for example 7.0 N / 18 mm or more, and 8.0 N after 1 day for the coated plate. / 18mm or more may be sufficient. A masking tape exhibiting such characteristics is excellent in surface shape followability for a mask object having a coating film. Although the upper limit of the peel strength after 1 day against the coated plate is not particularly limited, it is typically 15.0 N / 18 mm or less, and usually 12.0 N / 18 mm or less, from the viewpoint of suppressing changes in the appearance of the mask object.

  The masking tape according to a preferred embodiment may have a peel strength change rate measured by the method described in Examples described later in the range of −25% to + 25% (more preferably −20% to + 20%). preferable. A masking tape having such characteristics can achieve both a workability for attaching, a surface shape followability and a peeling workability at a high level in a well-balanced manner.

  The masking tape disclosed here preferably has a displacement distance at 23 ° C. of 0.15 mm or less in the holding force test described in the examples described later, from the viewpoint of non-glue residue and surface shape followability. More preferably, it is 0.10 mm or less. Further, the displacement distance at 40 ° C. is preferably 0.25 mm or less, more preferably 0.20 mm or less, and further preferably 0.15 mm or less.

  The masking tape disclosed here has a probe tack measured by the method described in the examples described later of 0.1 N / φ5 mm or more (for example, 0.3 N / φ5 mm or more) from the viewpoint of application workability. Further, it is preferably 2.0 N / φ5 mm or less (typically 1.5 N / φ5 mm or less, for example, 1.3 N / φ5 mm or less).

  The masking tape disclosed herein can be suitably used for an application for masking various mask objects (typically, an application for masking the mask object at least during painting). For example, it is suitable as a masking tape used by being attached to a metal surface or a painted surface. For example, acrylic, polyester, alkyd, melamine, urethane, nitrocellulose, acid-epoxy cross-linked, or a composite of these (for example, acrylic melamine, alkyd melamine), etc. It may be the surface of the coating film formed by the coating treatment used.

  Examples of preferable mask objects include metal plates (steel plates, stainless steel plates, aluminum plates, etc.); painted metal plates (for example, housing materials, building materials, and exterior bodies of transport machinery) with a coating on the surface of the metal plate. And the like, and the like, but not limited thereto, and the like. The said transport machine is not limited to what mainly transports a person, The thing for mainly transporting things other than a person may be used. Specific examples of transport machinery include aircraft (including airplanes, helicopters, air cushion boats, etc.), ships (including large ships, small ships, water scooters, etc.), railway vehicles (trains such as Shinkansen, diesel Transportation of cars, linear motor cars, cable cars, monorails, trolley buses, etc.), automobiles (including passenger cars, trucks, buses, auto three-wheelers, tractors, snow vehicles, bulldozers, amphibious vehicles, etc.) Machine included. The masking tape disclosed herein can be easily applied to a long range and can be excellent in peeling workability. Taking advantage of such features, it can be particularly preferably applied to the use of masking large transport machines such as airplanes, large ships, and railway vehicles during painting.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples. In the following description, “parts” and “%” are based on weight unless otherwise specified. Each characteristic in the following description was measured or evaluated as follows.

[Weight average molecular weight (Mw)]
The acrylic polymer aqueous dispersion was dried at 130 ° C. for 3 minutes to form an acrylic polymer layer having a thickness of about 35 μm. A sample of an acrylic polymer was collected from the acrylic polymer layer, immersed in toluene at room temperature for 7 days to elute soluble components, and the extract of the toluene soluble components was dried to obtain a measurement sample. This measurement sample was redissolved in tetrahydrofuran (THF) to prepare a 0.1 wt% THF solution. For the filtrate (sample solution for molecular weight measurement) obtained by filtering the THF solution with a membrane filter having an average pore size of 0.45 μm, Mw based on standard polystyrene was determined by a GPC measurement device. As the GPC measuring apparatus, model name “HLC-8320GPC” manufactured by Tosoh Corporation was used. The measurement conditions were as follows.
[GPC measurement conditions]
Column: TSKgel GMH-H (S) × 2
Column size: 7.8 mm I.D. D. × 300mm
Detector: Differential refractometer Eluent: THF
Flow rate: 0.6 mL / min Measurement temperature: 40 ° C
Sample injection volume: 100 μL

[Against SUS peel strength]
The pressure-sensitive adhesive sheet was cut into a strip having a width of 18 mm to prepare a test piece. In an environment of 23 ° C. and 50% RH, the test piece was pressed against a stainless steel plate (SUS plate) as an adherend by reciprocating a 2 kg roller once. After leaving this in an environment of 23 ° C. and 50% RH for 30 minutes, in accordance with JIS Z0237, a 180 ° peel strength [N / 18 mm] is measured using a tensile tester at a tensile speed of 300 mm / min. did.

[Peeling strength against painted plate]
(Peel strength after 2 hours)
The pressure-sensitive adhesive sheet was cut into a strip having a width of 18 mm to prepare a test piece. As the adherend, a coated plate having a layer of a lacquer coating (trade name “ANCHOR”, manufactured by DPI SDN.BHD) based on a modified nitrocellulose resin on its surface was used. The coated plate is coated with the lacquer paint in an environment of 23 ° C. and 50% RH and dried for 2 hours. The above-mentioned test piece was pressure-bonded to the painted plate by reciprocating a 2 kg roller once. The test piece attached to the painted plate was left in an environment of 23 ° C. and 50% RH for 2 hours. Then, according to JIS Z0237, 180 degree | times peel strength [N / 18mm] was measured on conditions with a tensile speed of 300 mm / min using the tensile tester.
(Peel strength after 1 day)
180 degree peel strength [N / 18 mm] was measured in the same manner except that the test piece attached to the coated plate was left in an environment of 23 ° C. and 50% RH for one day (about 24 hours).
(Peel strength after 30 minutes)
180 degree peel strength [N / 18 mm] was measured in the same manner except that the test piece attached to the coated plate was left in an environment of 23 ° C. and 50% RH for 30 minutes.

[Peel strength change rate]
From the measured value of the peel strength (P1) [N / 18 mm] after 2 hours against the coated plate and the measured peel strength (P2) [N / 18 mm] after 1 day against the coated plate, The peel strength change rate was calculated.
Peel strength change rate [%] = [(P2-P1) / P1] × 100

[Probe tack]
In an environment of 23 ° C. and 50% RH, a probe tack test was performed under the following conditions to measure the maximum value of adhesive strength.
Apparatus: Probe tack tester (manufactured by Tester Sangyo Co., Ltd.)
Probe: SUS, diameter 5mm
Contact load: 0.20N
Contact time: 1 second Peeling speed: 1 cm / second Contact speed: 1 cm / second

[Retention force test]
(23 ° C holding power)
The pressure-sensitive adhesive sheet was cut into a strip having a width of 18 mm to prepare a test piece. One end of the test piece was attached to an SUS plate as an adherend using a hand roller with an adhesion area of 18 mm in width and 18 mm in length. After maintaining this in an environment of 23 ° C. and 50% RH for 30 minutes, according to JIS Z0237, the SUS plate is suspended at a test temperature of 23 ° C. and 50% RH, and 500 g is added to the free end of the test piece. The load was applied. After holding for 1 hour at a test temperature of 23 ° C. and 50% RH with the load applied, the displacement distance (mm) of the test piece from the first attachment position was measured.
(40 ° C holding power)
In the same manner as described above, a test piece was attached to a SUS plate and held in an environment of 23 ° C. and 50% RH for 30 minutes, and then the SUS plate was suspended at a test temperature of 40 ° C. according to JIS Z0237. A load of 500 g was applied to the free end of the test piece. After holding for 1 hour at a test temperature of 40 ° C. with the load applied, the displacement distance (mm) of the test piece from the initial attachment position was measured.

[Coating test]
As the adherend, a test panel was used in which a steel plate was coated with the lacquer paint in an environment of 23 ° C. and 50% RH and dried for 2 hours. Each pressure-sensitive adhesive sheet was cut into a strip having a width of 18 mm, and attached to the painted surface (the surface coated with the lacquer paint) with a hand roller. The lacquer paint was sprayed on the area including the masked area. The resulting product was dried for 2 hours in an environment of 23 ° C. and 50% RH, and then the pressure-sensitive adhesive sheet was peeled off by hand. The appearance change on the surface of the coated film after peeling was visually observed, and the degree of appearance change suppression was evaluated according to the following three levels.
○: Residue, contamination, and emaciate were not observed.
Δ: No adhesive residue was observed, but either contamination or trace was observed.
X: Adhesive residue was recognized.

<< Experimental Example 1 >>
<Example 1>
[Synthesis of acrylic polymer (A1)]
A monomer component comprising 92 parts of 2-ethylhexyl acrylate (2EHA), 5 parts of n-butyl acrylate (BA), 2 parts of methyl methacrylate (MMA) and 1 part of methacrylic acid (MAA), and solid with respect to 100 parts of the monomer component An aqueous emulsion (monomer emulsion) of the monomer mixture was prepared by mixing and emulsifying 2 parts of an emulsifier with 100 parts of ion exchange water in minutes. As an emulsifier, sodium lauryl sulfate was used.
The monomer emulsion was placed in a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirring device, and stirred at room temperature for 1 hour or more while introducing nitrogen gas. Subsequently, the temperature of the system was raised to 60 ° C., and 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (polymerization initiator) (Wako Pure Chemical Industries, Ltd.) was added to the reaction vessel. Company, trade name “VA-057”) 0.1 part was added, and the monomer emulsion was reacted for 6 hours while maintaining the system at 60 ° C. After cooling the system to room temperature, the pH was adjusted to 7.5 by addition of 10% ammonium water to obtain an aqueous dispersion (A1e) of acrylic polymer A1. Mw of the toluene-soluble component (sol component) of this acrylic polymer A1 was 80 × 10 ⁴ .

[Preparation of pressure-sensitive adhesive composition (C1)]
A pressure-sensitive adhesive composition (C1) containing a rubber-based polymer and an acrylic polymer in a blend ratio (weight basis) of 90:10 was prepared.
Specifically, 90 parts of a natural rubber latex (trade name “TRDPL-51N”, Tyre-Tex Corp.) and 10 parts of the above acrylic polymer aqueous dispersion (A1e) in a solid part, Adhesive according to this example by mixing 9 parts of a tackifying resin with a solid content and 0.017 parts of a cross-linking agent with a solid content to 100 parts of the total amount of the solid content and the solid content of the aqueous dispersion. An agent composition (C1) was obtained. As the tackifying resin, an aqueous emulsion of rosin phenolic resin having a softening point of 150 ° C. (trade name “Tamanol E-200NT”, Arakawa Chemical Industries, Ltd.) was used. As the crosslinking agent, an epoxy-based crosslinking agent (trade name “E50-C”, Soken Chemical Co., Ltd.) was used. The pressure-sensitive adhesive composition (C1) had a gel fraction of 74%.

[Preparation of adhesive sheet (D1)]
Apply a rubber emulsion (trade name “TRMG-40N”, Tyleditex Co., Ltd.) as a primer on the first surface of crepe paper with a basis weight of 66 g / m ² , thickness of 116 μm, and air permeability of 26 seconds / 100 mL. And dried at 130 ° C. for 2 minutes to form an undercoat layer having a basis weight of 5 g / m ² . Next, an acrylic resin emulsion (trade name “NIKASOL FX-494”, Nippon Carbide Co., Ltd.) is applied to the second surface of the crepe paper (the surface opposite to the undercoat layer), and a temperature of 130 ° C. for 2 minutes. It dried and the back surface layer (back size layer) with a basic weight of 9 g / m < ² > was formed. Thus, the base material for masking tapes (base material (B1)) which concerns on this example was obtained.
The pressure-sensitive adhesive composition (C1) was applied to the undercoat layer side of the substrate (B1) and dried at 100 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 35 μm. In this way, a masking tape (adhesive sheet D1) according to this example was obtained.

<Examples 2 and 3 and Comparative Example 1>
The same procedure as in Example 1 was conducted, except that the amounts of the natural rubber latex and the acrylic polymer aqueous dispersion (A1e) were changed so that the blend ratios of the rubber polymer and the acrylic polymer were as shown in Table 1, respectively. The pressure-sensitive adhesive compositions (C2), (C3) and (C4) according to Examples 2 and 3 and Comparative Example 1 were prepared.

<Comparative example 2>
Adhesive containing no rubber polymer in the same manner as in Example 1 except that 90 parts of the natural rubber latex based on solid content was replaced with 90 parts of the acrylic polymer aqueous dispersion (A1e) based on solid content. A composition (C5) was prepared.

<Comparative Example 3>
A pressure-sensitive adhesive containing no acrylic polymer in the same manner as in Example 1 except that 10 parts of the acrylic polymer aqueous dispersion (A1e) based on the solid content was replaced with 10 parts of the natural rubber latex based on the solid content. A composition (C6) was prepared.

  The obtained adhesive sheet (masking tape) was evaluated by the method described above. The obtained results are shown in Table 1 together with the schematic configuration of the pressure-sensitive adhesive sheet according to each example.

  From the results shown in Table 1, Examples 1 to 3 in which the rubber / acryl ratio is in the range of 40/60 to 95/5 are compared to Comparative Example 2 containing only an acrylic polymer and Comparative Example 1 having a small rubber / acryl ratio. By comparison, it can be seen that the results of the coating test were clearly good. In Comparative Example 3 containing only the rubber-based polymer, the result of the coating test was good, but the peel strength after 2 hours against the coated plate was remarkably low and the rate of change in peel strength was extremely high compared to Examples 1-3. . In Examples 1 to 3, the rate of change in peel strength was significantly smaller than that in Comparative Examples 1 and 2, and it was confirmed that the peel strength was excellent in stability over time. In addition, Examples 1 to 3 have higher SUS peel strength than Comparative Examples 1 to 3, suggesting that the workability of attaching to a mask object (particularly a large mask object) is excellent.

<< Experimental example 2 >>
The materials used in this experimental example are shown below.

[Tackifying resin]
T1: Aqueous emulsion of rosin phenol resin having a softening point of 150 ° C., product name “Tamanol E-200NT”, Arakawa Chemical Industries, Ltd. product.
T2: aqueous emulsion of hydrogenated petroleum resin having a softening point of 100 ° C., product name “AM-1000-NT”, Arakawa Chemical Industries, Ltd. product.
T3: Aqueous emulsion of polymerized rosin ester having a softening point of 160 ° C., product name “Superester E-865NT”, Arakawa Chemical Industries, Ltd. product.
T4: An aqueous emulsion of a stabilized rosin ester having a softening point of 100 ° C., product name “Superester E-720”, Arakawa Chemical Industries, Ltd. product.

[Crosslinking agent]
X2: Isocyanate-based crosslinking agent (blocked isocyanate, product name “BL-400”, Bayer)
X3: Carbodiimide crosslinking agent (Product name “Carbodilite E-02”, Nisshinbo Co., Ltd.)

<Example 4>
A natural rubber latex (trade name “TRNA-60D”, Tyleditex Co., Ltd.) and an acrylic polymer aqueous dispersion (A1e) are used in an amount such that the blend ratio of the rubber polymer and the acrylic polymer is 67:33. A pressure-sensitive adhesive composition according to Example 4 was prepared by mixing 50 parts of tackifying resin T2 with respect to 100 parts of the total amount of the rubber-based polymer and the acrylic polymer. A pressure-sensitive adhesive sheet according to Example 4 was produced in the same manner as Example 1 except that this pressure-sensitive adhesive composition was used.

<Examples 5-9>
Except having used the kind and quantity of tackifying resin shown in Table 2, it carried out similarly to Example 4, and produced the adhesive sheet which concerns on Examples 5-9.

<Examples 10 to 14>
In the same manner as in Example 4 except that the tackifying resins T1 and T2 were used so that the total amount of T1 and T2 was the amount shown in Table 3 at a weight ratio of T1: T2 = 30: 20. The adhesive sheet which concerns on Examples 10-14 was produced.

<Examples 15 to 20>
Adhesive sheets according to Examples 15 to 20 were produced in the same manner as in Example 4 except that the types and amounts of tackifying resins and crosslinking agents shown in Table 4 were used.

  The obtained adhesive sheet (masking tape) was evaluated by the method described above. The obtained result is shown to Tables 2-4 with schematic structure of the adhesive sheet which concerns on each example. For easy understanding, Table 3 quotes the results of Examples 2 and 7 in Tables 1 and 2, and Table 4 quotes the results of Examples 4 and 9 in Table 2.

  As shown in Tables 2 to 4, the pressure-sensitive adhesive sheets of Examples 4 to 20 having a rubber / acryl ratio in the range of 40/60 to 95/5 showed good results in the coating test. From the results shown in Table 2, it can be seen that by using two or more kinds of tackifying resins, the peel strength against the coated plate can be improved as compared with the case where each tackifying resin is used alone. In particular, in Examples 7 and 8, good results were obtained. From the results shown in Table 3, it can be seen that the peel strength change rate can be suppressed by increasing the amount of the tackifying resin used. As shown in Table 4, the pressure-sensitive adhesive sheet of Example 9 using the tackifying resin T1 is a more suitable probe than the pressure-sensitive adhesive sheet of Example 15 using the tackifying resin T3 having the same softening point. Showed tack.

  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 Masking tape 10 Support body 10A Surface (1st surface)
10B Rear side (second side)
12 Paper substrate 12A First side 12B Second side 14 Undercoat layer (primer layer)
16 Back layer (back size layer)
20 Adhesive layer 30 Core material 100 Masking tape roll

Claims (10)

A support comprising a paper substrate;
An adhesive layer on the first surface of the support,
The pressure-sensitive adhesive layer includes a rubber polymer and an acrylic polymer, and a weight ratio of the rubber polymer to the acrylic polymer is 40/60 or more and 95/5 or less.   The masking tape according to claim 1, wherein the pressure-sensitive adhesive layer is obtained from a water-dispersed pressure-sensitive adhesive composition containing the rubber-based polymer and the acrylic polymer.   The masking tape of Claim 1 or 2 whose thickness of the said adhesive layer is 5 micrometers or more.   The said adhesive layer is a masking tape as described in any one of Claim 1 to 3 containing tackifying resin.   The masking tape according to claim 4, wherein the content of the tackifying resin is 50 parts by weight or less with respect to 100 parts by weight of the total amount of the rubber-based polymer and the acrylic polymer.   The masking tape of Claim 4 or 5 whose softening point of the said tackifying resin is 90 degreeC or more. 7. The masking tape according to claim 1, wherein the paper base has a basis weight of 15 g / m ² or more and 150 g / m ² or less and a thickness of 20 μm or more and 800 μm or less.   The masking tape as described in any one of Claim 1 to 7 whose peeling strength with respect to a stainless steel (SUS) board is 1.0 N / 18mm or more.   The masking tape as described in any one of Claims 1-8 whose peeling strength with respect to a SUS board is 10.0 N / 18mm or less.   The masking tape as described in any one of Claim 1 to 9 used for the exterior coating of a transport machine.

Images