JP7224577B1 - Separation and collection method of base material - Google Patents

Abstract

A method for efficiently separating and recovering a substrate from a laminate in which a support, an adhesive layer and a substrate are laminated in this order is provided. The above object is a method for separating and recovering a substrate from a laminate in which a substrate, an adhesive layer and a substrate are laminated in this order, wherein the substrate has a Gurley air permeability of 10 to 1000. second/100 ml non-woven fabric or air-permeable film, including a step of immersing the laminate in a detachment liquid to detach the substrate from the pressure-sensitive adhesive layer, wherein the detachment liquid has a pH of 13.0 at 25°C. 3 or more, and the dynamic surface tension of the desorbing liquid measured at 25° C. for 1000 msec is 60 mN/m or less. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a method for separating and recovering a substrate from a laminate obtained by laminating a substrate and an adhesive sheet having an adhesive layer and a support.

In recent years, the amount of general waste or industrial waste, including packages made from plastic films, plastic bottles, and other plastic products, has been steadily increasing, and waste disposal has become an important environmental problem.
Examples of the plastic product include a food packaging package using a plastic film, and such a food packaging package may be laminated with a sheet including a pressure-sensitive adhesive layer. Such multi-layered food packaging packages have a problem that they cannot be recycled as they are because different kinds of materials are mixed.
Regarding the material recycling of such multilayer packaging materials, for example, Patent Document 1 discloses that a water-disintegratable or alkali-disintegratable base paper is used as a support, and at least one surface of the base paper has an adhesive area. An adhesive sheet is disclosed. Further, Patent Document 2 discloses an alkali-peelable film label to be attached to a product or its container.

JP 2010-043226 A JP-A-2003-241669

However, in Patent Document 1, the amount of residue when the base paper is subjected to the disaggregation test is less than 50 mg, preferably all disaggregation, but the disaggregated pulp and the plastic film piece as the substrate are used as a filter. When trying to separate by filtration, there is a problem that the pulp dispersion aggregates the film pieces due to the filtration pressure, clogging the filter. This problem may be solved by introducing a filtration device with a filter cleaning function, but the initial investment cost will be high, and the pulp component will eventually have to be disposed of, so the recycling efficiency will be low. put away.
Also, when price tag stickers are used for plastic packaging materials such as food trays and packs, frost and condensation that occur during chilled storage or when changing the storage environment from frozen to refrigerated are sufficient. However, in the case of the film label described in Patent Document 2, the alkaline processing liquid is only exposed from the adhesive-exposed part at the end when the label is peeled off with alkali. Since it cannot work, it is necessary to increase the alkali release property of the adhesive. Then, it becomes necessary to increase the hydrophilicity of the pressure-sensitive adhesive, and there is a problem that it becomes difficult to achieve compatibility with water-resistant adhesive strength.
Accordingly, an object of the present invention is to provide a method for efficiently separating and recovering a substrate from a laminate obtained by laminating a substrate and a pressure-sensitive adhesive sheet having both alkali peelability and water-resistant adhesive strength.

The inventors of the present invention have completed the present invention as a result of earnest studies in order to solve the above problems.
That is, the present invention relates to the following [1] to [3].

[1] A method of separating and recovering a substrate from a laminate in which a support, an adhesive layer and a substrate are laminated in this order,
The support is a nonwoven fabric or a breathable film having a Gurley air permeability of 10 to 1000 sec/100 ml,
including a step of detaching the base material from the adhesive layer by immersing the laminate in a detachment liquid,
The desorbed liquid has a pH of 13.3 or higher at 25°C,
And the dynamic surface tension of the desorbed liquid at 1000 msec measured at 25 ° C. is 60 mN / m or less,
A method for separating and recovering a base material.

[2] The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer containing an acrylic copolymer, the acrylic copolymer is a copolymer of a monomer mixture containing a (meth)acrylate having a carboxyl group, and the The method for separating and recovering a substrate according to [1], wherein the acrylic copolymer has an acid value of 0.1 to 100 mgKOH/g.

Further, according to an embodiment of the present invention, the method for separating and recovering a substrate according to [1] or [2], wherein the coating amount of the adhesive layer is 10 to 30 g/m ² .

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for efficiently separating and recovering a base material from a laminate obtained by laminating a base material and a pressure-sensitive adhesive sheet having both alkali peelability and water-resistant adhesive strength.

The present invention will be described in detail below. It goes without saying that other embodiments are also included in the scope of the present invention as long as they match the gist of the present invention. In addition, in the present specification, the numerical range specified using "-" includes the numerical values described before and after "-" as the range of lower and upper values.
Terms are defined before describing the present invention in detail. (Meth)acrylic acid includes acrylic acid and methacrylic acid. (Meth)acrylates include acrylates and methacrylates. A monomer is a monomer having an ethylenically unsaturated double bond.
Unless otherwise noted, the various components appearing in this specification may be used singly or in admixture of two or more.

The present invention provides a laminate obtained by laminating an adhesive layer, an adhesive sheet having a nonwoven fabric or a breathable film having a Gurley air permeability of 10 to 1000 seconds/100 ml as a support, and a substrate, at 25°C. Detaching the substrate from the laminate by immersing it in a desorption liquid having a pH of 13.3 or more and a dynamic surface tension of 60 mN/m or less at 25° C. for 1000 msec. It is a separation and recovery method.

≪Laminate≫
The laminate used in the present invention is obtained by laminating a support, an adhesive layer and a substrate in this order. There is no particular limitation on the method for producing the laminate, and it can be produced by a conventionally known method. For example, it can be produced by laminating a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer and a support and a substrate.

<Adhesive sheet>
The pressure-sensitive adhesive sheet can be formed by coating a support with a pressure-sensitive adhesive composition, which will be described later, and drying it. Alternatively, it can be formed by coating a release liner with a pressure-sensitive adhesive composition described later, drying it to form a pressure-sensitive adhesive layer, and then laminating a support. The support is a nonwoven fabric or a breathable film having a Gurley air permeability of 10 to 1000 seconds/100 ml. By using a support having a Gurley air permeability of 1,000 seconds/100 ml or less, the permeability of the stripping liquid to the support in the laminate is improved, and the contact area between the adhesive layer and the stripping liquid is improved for detachment. Efficiency can be improved. In order to further improve the desorption efficiency, the Gurley air permeability is preferably 100 seconds/100 ml or less.
In addition, by setting the Gurley air permeability of the support to 10 seconds/100 ml or more, the water-resistant adhesive strength of the adhesive sheet is maintained, and it becomes possible to prevent water immersion peeling when frost or dew condensation occurs. .
The waterproof adhesive strength can be evaluated, for example, by the method described in Examples. The water resistant adhesive strength measured by this method should be 300 gf/25 mm or more, preferably 350 gf/25 mm or more, and most preferably 450 gf/25 mm or more.

The Gurley air permeability is measured by the method described in JIS P8117:2009. It is also possible to convert ISO air permeability or Oken air permeability into Gurley air permeability by the method described in JIS P8117:2009.

(support)
The material of the support of the present invention is not particularly limited. For example, olefins such as polyethylene or polypropylene, polyesters such as polyethylene terephthalate, petroleum-based materials such as polyamides, recycled fibers such as rayon and cupra, and natural fibers such as cotton can be used. A petroleum-based material is preferred because the fibers are finely dispersed in the desorbing agent of the present invention and can cause filtration problems. When a non-woven fabric is used as the support, a spun lace method, a spun bond method, a thermal bond method, an air through method, a needle punch method, or the like can be used as a processing method. When a breathable film is used as the support, a stretching method or the like can be used.

The nonwoven fabric can be combined with a filling agent to adjust its air permeability. The method of compositing is not particularly limited, and includes coating methods such as roll coater, blade coater, gravure coater, air knife coater, bar coater, and spray, impregnation methods such as size press and dip, and the like. Coating is preferred from the viewpoint of

When the nonwoven fabric and the filler are combined, the acid value of the filler is preferably 20 mgKOH/g or more, more preferably 25 mgKOH/g or more, from the viewpoint of releasability.

The nonwoven fabric can be calendered to adjust its air permeability. The calendering process is appropriately used on-machine or off-machine, and the form of the pressurizing device, scum in the pressurizing nip, heating, etc., are appropriately adjusted according to the usual calendering device.

[Release liner]
As the release liner (sometimes referred to as a separator), conventionally known ones can be used without particular limitation. For example, a release agent such as fluororesin or silicone resin is applied to a suitable substrate (e.g., glassine paper, kraft paper, clay coated paper, paper laminated with a resin film such as polyethylene, resin such as polyvinyl alcohol or acrylic copolymer). A release liner obtained by treating at least one surface of a paper coated with

[Coating method]
A known method can be used for the coating method, and various known coating devices such as a comma coater, reverse coater, slot die coater, lip coater, gravure chamber coater, and curtain coater can be used to coat the support or the release liner. The pressure-sensitive adhesive sheet of the present invention can be obtained by coating and drying. In this case, it is preferable to dry at 80° C. to 120° C. after applying the pressure-sensitive adhesive composition to a release liner or the like. By setting the drying temperature to 80° C. or higher, a pressure-sensitive adhesive sheet can be obtained in an appropriate time, and by setting the drying temperature to 120° C. or lower, thermal deterioration of the support or release liner can be prevented.

The coating amount of the pressure-sensitive adhesive layer is preferably 10 to 30 g/m ² from the viewpoint of achieving both water-resistant adhesiveness and releasability. When it is 10 g/m ² or more, it is easier to secure water-resistant adhesiveness, and when it is 30 g/m ² or less, it is easier to secure releasability.

In addition, the pressure-sensitive adhesive sheet of the present invention preferably has an adhesive strength of 3 N or more in a 180° peel test for non-removable food packaging applications.
The 180° peel test method is as follows. A sheet containing a pressure-sensitive adhesive layer and a support is prepared in a size of 25 mm in width and 100 mm in length, and the pressure-sensitive adhesive layer exposed by peeling off the release sheet from the pressure-sensitive adhesive sheet under an atmosphere of 23° C. and a relative humidity of 50% is used as a base material. and crimped once with a 2 kg roll. After leaving it for 24 hours, it is peeled off at a speed of 300 mm/min in a direction of 180 degrees using a tensile tester.

(Adhesive layer)
The pressure-sensitive adhesive layer in the present invention plays a role of separating the base material by dissolution, peeling, or the like with a release liquid. The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition, and examples of resins contained in the pressure-sensitive adhesive composition include acrylic copolymers, urethane copolymers, polyester copolymers, polyamide copolymers, and the like. but preferably contains an acrylic copolymer.

((acrylic copolymer))
An acrylic copolymer is a copolymer obtained by polymerizing a (meth)acrylate monomer mixture. Examples of (meth)acrylate monomers include (meth)acrylates having a carboxyl group, (meth)acrylates having an alkyl group, (meth)acrylates having an ethylene glycol chain or propylene glycol chain, and (meth)acrylates having a hydroxyl group. It is preferred that a (meth)acrylate having a carboxyl group is included from the viewpoint of elimination.

Also, the acid value of the acrylic copolymer is preferably 0.1 to 100 mgKOH/g. When the acid value of the acrylic copolymer is 0.1 to 100 mgKOH/g, it becomes easier to achieve both water-resistant adhesion and releasability.

[(Meth)acrylate having a carboxyl group]
Examples of (meth)acrylates having a carboxyl group include (meth)acrylic acid, β-carboxyethyl acrylate, ω-carboxypolycaprolactone monoacrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, and the like. mentioned. The use of (meth)acrylic acid is preferred in terms of adhesive performance and cost.

[(Meth)acrylate having an alkyl group]
Examples of (meth)acrylates having an alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, and n-hexyl (meth)acrylate. Acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate Acrylate, dodecyl (meth)acrylate and the like.

[(Meth)acrylate having an ethylene glycol chain or propylene glycol chain]
(Meth)acrylates having an ethylene glycol chain or a propylene glycol chain include methoxy (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate. ) acrylate, ethoxypolypropylene glycol (meth)acrylate, and the like.

[(Meth)acrylate having a hydroxyl group]
(Meth)acrylates having a hydroxyl group are, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxy Hydroxyalkyl (meth)acrylates such as butyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, polyethylene glycol mono (meth)acrylate, Glycol mono(meth)acrylates such as polypropylene glycol mono(meth)acrylate and 1,4-cyclohexanedimethanol mono(meth)acrylate.

[Other monomers]
Monomers other than the above can also be used as long as they are copolymerizable with (meth)acrylate monomers. Other monomers include, for example, acetoacetoxyethyl (meth)acrylate, 3-(trimethoxysilyl)propyl (meth)acrylate, 3-(triethoxysilyl)propyl (meth)acrylate, 3-(methyldimethoxysilyl)propyl ( Self-crosslinking monomers such as meth)acrylate, 3-(methyldiethoxysilyl)propyl (meth)acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl methacrylate, Epoxy group-containing monomers such as 1,2-epoxy-4-vinylcyclohexane, aminomethyl (meth) acrylate, dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, etc. Amino group-containing monomers, amide group-containing monomers such as (meth)acrylamide and diacetone (meth)acrylamide, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, N-methylitaconimide, N -ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, N-(meth)acryloyloxymethylenesuccinimide, N-( Imido group-containing monomers such as meth)acryloyl-6-oxyhexamethylenesuccinimide and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, vinyl acetate, styrene, methylstyrene, vinyltoluene, acrylonitrile and other vinyl monomers, etc. is mentioned.

((Production of acrylic copolymer))
An acrylic copolymer is a copolymer obtained by polymerizing a (meth)acrylate monomer mixture. The method of polymerization includes usual polymerization methods such as solution polymerization and emulsion polymerization.

[Production by emulsion polymerization]
Acrylic copolymers can be obtained, for example, by emulsion polymerization.
First, the monomers are mixed to form a uniform mixed solution. This mixed solution may be subjected to polymerization as it is, or may be subjected to polymerization after adding a part or all of water and a surfactant and stirring to form an emulsified liquid.

After preparing these mixed solutions or emulsions, polymerization is carried out in the presence of a polymerization initiator. After charging the reaction vessel and starting polymerization, it may be further divided into several additions, or after charging a part of it into the reaction vessel and starting polymerization, the rest may be continuously added dropwise, or water and necessary A part or the whole amount of the surfactant may be charged in a reaction vessel, and the whole amount may be added dropwise continuously. In the case of polymerization using a mixed solution, it is preferable to charge the reaction vessel with the total amount of the surfactant and part or all of the water in advance.

As a method of adding the polymerization initiator, the whole amount may be charged in the reaction vessel in advance, the whole amount may be added after the temperature is raised, or a part is charged in the reaction vessel and after the polymerization is started, it is added several times. It may be divided into two and dividedly added, a part may be charged into a reaction vessel and after polymerization is started, the rest may be continuously added dropwise, or the whole amount may be continuously added dropwise. When the polymerization initiator is dividedly added or continuously dropped, it may be dividedly added or continuously dropped into the reaction vessel alone, or may be dividedly added or continuously dropped in a state of being mixed with a mixed solution or emulsion. good. After adding the polymerization initiator by these methods, the polymerization initiator may be added once or twice or more for the purpose of increasing the reaction rate. Thus, the acrylic copolymer of the present invention can be obtained.

Surfactants used in emulsion polymerization are preferably appropriately selected from anionic surfactants and nonionic surfactants. Further, the surfactant may be a reactive surfactant having a radically polymerizable functional group, or a non-reactive surfactant having no radically polymerizable functional group. They can also be used in combination.

Among surfactants, reactive surfactants are anionic surfactants having one or more radically polymerizable unsaturated double bonds in the molecule. Examples thereof include sulfosuccinic acid ester-based surfactants, alkylphenol ether-based surfactants, and the like.

Non-reactive anionic surfactants include, for example, polyoxyethylene polycyclic phenyl ether sulfates, higher fatty acid salts such as sodium stearate, alkylarylsulfonates such as sodium dodecylbenzenesulfonate, and alkyl surfactants such as sodium lauryl sulfate. Examples include sulfate salts, polyoxyethylene alkyl ether sulfate salts such as sodium polyoxyethylene lauryl ether sulfate, and polyoxyethylene alkyl aryl ether sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate.

Non-reactive nonionic surfactants include, for example, polyoxyethylene alkylphenyl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether; polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene polyoxyethylene alkyl ethers such as oleyl ether; polyoxypolycyclic phenyl ethers such as polyoxyethylene distyrenated phenyl ether; and polyoxyethylene sorbitan fatty acid esters. Surfactants can be used alone or in combination of two or more.

Among the surfactants described above, it is preferable to use a reactive or non-reactive anionic surfactant because good polymerization stability can be obtained. It is preferable to use 0.5 to 3 parts by weight of the surfactant per 100 parts by weight of the monomer mixture.

A polymerization initiator is used for emulsion polymerization. The polymerization initiator may be either water-soluble or oil-soluble, but when using an oil-soluble initiator, it is necessary to dissolve it in a water-miscible solvent in advance. It is preferred to use agents.

Water-soluble polymerization initiators include, for example, potassium persulfate, sodium persulfate, ammonium persulfate, ammonium (amine) salt of 4,4′-azobis-4-cyanovaleric acid, 2,2′-azobis(2-methyl amidoxime) dihydrochloride, 2,2'-azobis(2-methylbutanemidoxime) dihydrochloride tetrahydrate, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl )-2-hydroxyethyl]-propionamide}, 2,2′-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] and the like. Among these, potassium persulfate and sodium persulfate are preferred.

The water-soluble polymerization initiator is preferably used in an amount of 0.01 to 1.0 parts by mass, more preferably 0.02 to 0.5 parts by mass, per 100 parts by mass of the monomer mixture. When the content is 0.01 to 1.0 parts by mass, the polymerization reactivity can be further improved.

Furthermore, the water-soluble polymerization initiator can be a redox polymerization initiator (using both an oxidizing agent and a reducing agent). Examples of the oxidizing agent include ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, p-methane hydroperoxide and the like. Examples of reducing agents include sodium sulfite, sodium acid sulfite, Rongalite, ascorbic acid, and the like.

The redox polymerization initiator is preferably used in an amount of 0.01 to 1.0 parts by mass, more preferably 0.02 to 0.5 parts by mass, with respect to 100 parts by mass of the monomer mixture for each of the oxidizing agent and the reducing agent. preferable. When the content is 0.01 to 1.0 parts by mass, the polymerization reactivity can be improved.

Buffers can be used to adjust the pH as needed during emulsion polymerization. The buffering agent is not particularly limited as long as it has a pH buffering action for the reaction solution for emulsion polymerization. Buffers include, for example, sodium hydrogen carbonate, potassium hydrogen carbonate, monosodium phosphate, monopotassium phosphate, disodium phosphate, trisodium phosphate, sodium acetate, ammonium acetate, sodium formate, ammonium formate, trisodium citrate, and the like. are mentioned.

The buffering agent is preferably used in an amount of less than 5 parts by mass, more preferably less than 3 parts by mass, relative to 100 parts by mass of the monomer mixture.

A chain transfer agent may be used as necessary to adjust the molecular weight during emulsion polymerization. Compounds having, for example, a thiol group or a hydroxyl group are generally known as chain transfer agents. Examples of compounds having a thiol group include mercaptans such as lauryl mercaptan, 2-mercaptoethyl alcohol, dodecyl mercaptan, and mercaptosuccinic acid, alkyl mercaptopropionates such as n-butyl mercaptopropionate and octyl mercaptopropionate, and mercaptopropionate. and alkoxyalkyl mercaptopropionate such as methoxybutyl acid. Also included are alcohols such as methyl alcohol, n-propyl alcohol, isopropyl alcohol (IPA), t-butyl alcohol, and benzyl alcohol. A chain transfer agent can be used alone or in combination of two or more.
The chain transfer agent is preferably 0.01 to 7.5 parts by mass, more preferably 0.03 to 3.0 parts by mass, per 100 parts by mass of the monomer mixture.

Furthermore, known additives such as neutralizers, leveling agents, preservatives, antifoaming agents, thickeners, and pigment dispersions can be blended as optional components.

In order to adjust the pH of the acrylic copolymer, the neutralizing agent is preferably added in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the acrylic copolymer. By blending 0.1 to 5 parts by mass, the pH of the acrylic copolymer can be adjusted, and the storage stability of the acrylic copolymer is enhanced.

The amount of the leveling agent to be blended is preferably 0.1 to 1 part by mass per 100 parts by mass of the acrylic copolymer. By blending 0.1 part by mass or more, the leveling property at the time of coating is improved, and cissing and shrinkage can be suppressed. By blending it in an amount of 1 part by mass or less, it is possible to suppress deterioration in adhesive strength and removability when the adhesive layer is formed.

The amount of the antiseptic to be added is preferably 0.1 to 1 part by mass per 100 parts by mass of the acrylic copolymer. By blending 0.1 parts by mass or more, it is possible to suppress putrefaction and bacterial growth of the water-based adhesive. By blending it in an amount of 1 part by mass or less, it is possible to suppress deterioration in adhesive strength and removability when the adhesive layer is formed.

The antifoaming agent is preferably added in an amount of 0.1 to 1 part by mass per 100 parts by mass of the acrylic copolymer. By blending 0.1 parts by mass or more, foaming during coating of the water-based adhesive can be suppressed, and repelling due to foaming can be suppressed. By blending it in an amount of 1 part by mass or less, it is possible to suppress deterioration in adhesive strength and removability when the adhesive layer is formed.

The amount of the thickener to be blended is preferably 0.1 to 5 parts by mass per 100 parts by mass of the acrylic copolymer. By blending 0.1 parts by mass or more, the water-based pressure-sensitive adhesive can be thickened, and shrinkage and cissing during coating can be suppressed. By blending it in an amount of 5 parts by mass or less, it is possible to suppress deterioration in adhesive strength and removability when the adhesive layer is formed.

Pigment dispersions are used when the pressure-sensitive adhesive layer requires concealability and color development. The amount of the pigment dispersion to be blended is preferably 0.1 to 5 parts by mass per 100 parts by mass of the acrylic copolymer. By blending 0.1 part by mass or more, it is possible to enhance the concealability and color developability of the pressure-sensitive adhesive layer. By blending it in an amount of 5 parts by mass or less, it is possible to suppress deterioration in adhesive strength and removability when the adhesive layer is formed.

[Manufacturing by solution polymerization]
The acrylic copolymer can also be obtained by adding a polymerization initiator to the monomer mixture and carrying out solution polymerization. Solvents used in the solution polymerization include, for example, methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, hexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, n-propanol, and isopropanol. is preferred, and ethyl acetate is more preferred.

The solution polymerization is preferably carried out by adding about 0.001 to 1 part by mass of a polymerization initiator to 100 parts by mass of the monomer mixture. Generally, the polymerization can be carried out at a temperature of about 50° C. to 90° C. for 6 hours to 20 hours under nitrogen stream. Moreover, in the polymerization, a chain transfer agent can be used to appropriately adjust the molecular weight of the copolymer.

Chain transfer agents used in solution polymerization include, for example, n-dodecylmercaptan, mercaptoisobutyl alcohol, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, glycidylmercaptan. , α-methylstyrene dimer, carbon tetrachloride, chloroform, and hydroquinone. About 0.01 to 1 part by mass of the chain transfer agent can be used with respect to 100 parts by mass of the monomer mixture.

Polymerization initiators used in solution polymerization are generally azo compounds and organic peroxides.
Azo compounds include, for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 1,1′-azobis(cyclohexane 1-carbonitrile), 2,2 '-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4 , 4′-azobis(4-cyanovaleric acid), 2,2′-azobis(2-hydroxymethylpropionitrile), and 2,2′-azobis(2-(2-imidazolin-2-yl)propane ) and the like.

Organic peroxides are, for example, benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate , t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

[Curing agent]
The pressure-sensitive adhesive layer in the invention can further contain a curing agent. Examples of curing agents include titanium chelate compounds, aluminum chelate compounds, zirconium chelate compounds, zinc oxide, aziridine compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, hydrazide compounds, and the like. Curing agents can be used alone or in combination of two or more.
The curing agent is preferably blended in an amount of 0.01 to 10 parts by mass, more preferably 0.03 to 8 parts by mass, per 100 parts by mass of the acrylic copolymer. Addition of 0.01 to 10 parts by mass further improves adhesion to the substrate and cohesion.

[Tackifying resin]
The pressure-sensitive adhesive layer in the present invention may further contain a tackifying resin. Examples of tackifying resins include rosin-based tackifying resins, synthetic hydrocarbon-based tackifying resins, terpene-based tackifying resins, terpene-phenol-based tackifying resins, and emulsion types using these. By including these tackifying resins, the waterproof adhesive strength can be further improved.

Rosin-based tackifying resins include rosin esters obtained by esterifying unmodified rosins such as gum rosin, tall oil rosin, and wood rosin with alcohol, and modified rosins such as disproportionated rosins obtained by modifying unmodified rosins, polymerized rosins, and hydrogenated rosins. , modified rosin esters such as disproportionated rosin esters obtained by further esterifying these modified rosins with alcohol, polymerized rosin esters and hydrogenated rosin esters, and rosin phenol obtained by adding phenol to unmodified rosins are preferred. Among these, rosin esters and modified rosin esters are preferred because they further improve adhesive strength and transparency. In the rosin ester and the modified rosin ester, some hydroxyl groups of the alcohol used for esterification may remain unreacted. Examples of alcohols used for esterification include monofunctional alcohols such as methanol, bifunctional alcohols such as ethylene glycol, trifunctional alcohols such as glycerin, and tetrafunctional alcohols such as pentaerythritol. Trifunctional or less alcohols are preferred in consideration of solubility.

Synthetic hydrocarbon-based tackifying resins include, for example, coumarone-based resins, coumarone-indene-based resins, styrene-based resins, xylene-based resins, phenol-based resins, and petroleum-based resins.

The softening point of the tackifying resin is preferably from 0 to 160°C, more preferably from 0 to 120°C, even more preferably from 0 to 100°C. When the softening point of the tackifier resin is from 0 to 160° C., it becomes easy to achieve both adhesive physical properties and releasability. The softening point is the softening temperature measured according to the dry bulb method specified in JISK5902.

The tackifying resin is preferably used in an amount of 10 to 50 parts by mass, more preferably 15 to 40 parts by mass, per 100 parts by mass of the copolymer (A). By using 10 to 50 parts by mass of the tackifying resin, it becomes easy to achieve both waterproof adhesive strength and releasability.

<Base material>
Examples of the substrate constituting the laminate include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene, polyester resins such as polyethylene terephthalate, vinyl acetate resins, polyimide resins, fluorine resins, polyvinyl chloride resins, Examples include plastic films made of resin materials such as cellophane, polyethylene nonwoven fabrics, polyester nonwoven fabrics, vinylon nonwoven fabrics, and the like. The substrate may be a single layer or a laminate of multiple layers. In addition, on the substrate, a printed layer for displaying a product name, decoration, and aesthetic appearance, and an overcoat layer for protecting the printed layer and imparting design properties such as gloss. may be provided. From the viewpoint of releasability and recyclability after separation and recovery, it is preferable not to include a printed layer or an overcoat layer.

In the present invention, "detachment" refers to detachment of the base material from the laminate by dissolving or swelling the adhesive layer with a detachment liquid and peeling off the adhesive layer. It includes both the case of detachment and the case of detachment of the base material due to neutralization, swelling, etc. even if the adhesive layer does not dissolve.

Since the object of the present invention is to obtain a substrate after detachment as a recycled or recycled substrate, it is preferable to remove as much of the adhesive layer and the like as possible from the substrate. Specifically, it is preferable that at least 50% by mass or more of 100% by mass of the pressure-sensitive adhesive layer is detached in the area or film thickness direction. More preferably 60% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more are desorbed.
After the substrate is immersed in the desorption liquid and the substrate is detached, the substrate recovery step can be freely selected according to the materials of the support material and substrate, such as specific gravity separation and size separation.

≪Desorption liquid≫
The release liquid has a dynamic surface tension of 60 mN/m or less at 25° C. for 1,000 msec. In addition, by setting the pH of the release liquid to 13.3 or more at 25° C., the pressure-sensitive adhesive layer can be swollen or dissolved, and the separation from the substrate can be promoted, so the separation efficiency between the support and the substrate is improved. improves.
The desorbed liquid should have a dynamic surface tension of 60 mN/m or less at 1000 msec measured at 25°C and a pH of 13.3 or more at 25°C. An aqueous solution is preferable from the viewpoint of maintaining the properties of the recycled material using the base material. These desorbed liquids may be heated.

[Dynamic surface tension modifier]
Any dynamic surface tension modifier may be used to reduce the dynamic surface tension, preferably a surfactant.

Types of surfactants include, for example, nonionic, anionic, cationic, and amphoteric surfactants, and suitable types and blending amounts can be appropriately selected and used according to required properties. At least one of a nonionic surfactant and an anionic surfactant is preferably included from the viewpoint of releasability and foamability.
In addition, it is preferable that the surfactant has a structure to which alkylene oxide (hereinafter also referred to as AO) is added, because detachment and reattachment properties are improved.

(Nonionic surfactant)
The nonionic surfactant is not particularly limited as long as it has a dynamic surface tension lowering ability, but an alkylene oxide adduct to which an alkylene oxide is added is preferred. More preferably, compounds obtained by adding alkylene oxide to alcohols having active hydrogen (alcohol-based nonionic surfactants), compounds obtained by adding alkylene oxide to amines (amine-based nonionic surfactants ), or a compound obtained by adding an alkylene oxide to a fatty acid (fatty acid-based nonionic surfactant). The addition may be either random addition or block addition. Also, the carbon number of the alkylene oxide is preferably 2 to 4 carbon atoms.

[Alcohol-based nonionic surfactant]
Examples of alcohol-based nonionic surfactants include alkylene oxide adducts of primary or secondary alcohols having a total carbon number of 8 to 24, or alkylene oxide adducts of alkylphenols having a total carbon number of 8 to 12. be done. The primary or secondary alcohol having a total carbon number of 8 to 24 may be either saturated or unsaturated.
Examples of primary or secondary alcohols having a total carbon number of 8 to 24 include lauryl alcohol, stearyl alcohol, oleyl alcohol, dodecyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, and myristyl alcohol.
Examples of the alkylene oxide to be added to the alcohol include ethylene oxide, propylene oxide and butylene oxide, and ethylene oxide is preferably essential. The number of moles of alkylene oxide to be added is preferably 1 to 100 mol, more preferably 2 to 50 mol, per 1 mol of alcohol or alkylphenol. It is preferable that it is in the above range because it is particularly excellent in releasability.

[Amine-based nonionic surfactant]
Amine-based nonionic surfactants include alkylene oxide adducts of saturated or unsaturated primary or secondary amines having a total of 8 to 36 carbon atoms. Amines include 2-ethylhexylamine, di-2-ethylhexylamine, laurylamine, dilaurylamine, tetradecylamine, ditetradecylamine, hexadecylamine, dihexadecylamine, stearylamine, distearylamine, oleylamine, di and oleylamine. The type and number of moles of alkylene oxide to be added are the same as those described in the section [Alcoholic Nonionic Surfactant] above.

[Fatty acid-based nonionic surfactant]
The structure of the fatty acid-based nonionic surfactant is not particularly limited. Examples include oils and fats composed of esters of higher fatty acids and glycerin, and alkylene oxide adducts of mixtures of the above oils and fats and 2 to 10 polyhydric alcohols. The higher fatty acid having 10 to 24 total carbon atoms may be either saturated or unsaturated.
Examples of the higher fatty acids having 10 to 24 carbon atoms in total include saturated higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, palmitoleic acid, oleic acid, elaidic acid, linoleic acid, unsaturated higher fatty acids such as linolenic acid, erucic acid and ricinoleic acid; Dihydric to decahydric polyhydric alcohols include ethylene glycol, propylene glycol, glycerin, polyglycerin, sorbitol, sorbitan, sucrose and the like. The type and number of moles of alkylene oxide to be added are the same as those described in the section [Alcoholic Nonionic Surfactant] above.

(Anionic surfactant)
The anionic surfactant is preferably a non-soap surfactant, such as a sulfonate anionic surfactant, a sulfate ester anionic surfactant, a carboxylic acid anionic surfactant, a phosphate ester anionic surfactant. active agents.
[Sulfonic acid-based anionic surfactant]
Examples of the sulfonic acid anionic surfactant include alkylsulfonic acid, alkylbenzenesulfonic acid, alkylnaphthalenesulfonic acid, alkyldiphenyletherdisulfonic acid, alkylmethyltaurine, sulfosuccinic acid diester, alkylene oxide adduct of sulfonic acid, and these. salt of Specific examples include hexanesulfonic acid, octanesulfonic acid, decanesulfonic acid, dodecanesulfonic acid, toluenesulfonic acid, cumenesulfonic acid, octylbenzenesulfonic acid, dodecylbenzenesulfonic acid, dinitrobenzenesulfonic acid, and lauryldodecylphenyl ether disulfone. An acid or the like can be used.

[Sulfuric Acid Ester-Based Anionic Surfactant]
Examples of the above-mentioned sulfate ester-based anionic surfactants include sulfate esters (alkyl ether sulfate esters), alkylene oxide adducts of sulfate esters, and salts thereof. Specific examples include lauryl sulfuric acid, myristyl sulfuric acid, polyoxyethylene lauryl ether sulfuric acid, and the like.

[Carboxylic acid-based anionic surfactant]
Examples of the carboxylic acid-based anionic surfactants include alkylcarboxylic acids, alkylbenzenecarboxylic acids, alkylene oxide adducts of carboxylic acids, and salts thereof. Specific examples include lauric acid, myristic acid, palmitic acid, stearic acid, polyoxyethylene lauryl ether acetic acid, and polyoxyethylene tridecyl ether acetic acid.

[Phosphate Ester Anionic Surfactant]
Examples of the phosphate ester-based anionic surfactants include phosphate esters (alkyl ether phosphate esters), alkylene oxide adducts of phosphate esters, and salts thereof. Specific examples include octyl phosphate, lauryl phosphate, tridecyl phosphate, myristyl phosphate, cetyl phosphate, stearyl phosphate, polyoxyethylene octyl ether phosphate, and polyoxyethylene lauryl ether phosphate. etc. can be used.

The anionic surfactant preferably has an alkyl group of 2 to 24 carbon atoms or an alkenyl group of 2 to 24 carbon atoms, more preferably an alkyl group of 8 to 18 carbon atoms. The alkyl group or alkenyl group may be linear or branched.

When the anionic surfactant is an alkylene oxide adduct, examples of the alkylene oxide include ethylene oxide, propylene oxide and butylene oxide, with ethylene oxide being preferred. The number of moles of alkylene oxide to be added is preferably 1 to 12 mol, more preferably 1 to 8 mol, per 1 mol of alcohol or alkylphenol. It is preferable that it is in the above range because it is particularly excellent in releasability.

Examples of salts constituting the above-mentioned anionic surfactants include metal salts of sodium, potassium, magnesium, calcium and the like. These salts may be used individually by 1 type, and may be used in combination of 2 or more type.
Among them, the anionic surfactant is preferably a sulfonate type or a phosphate type, more preferably an alkyl sulfonate or a polyoxyalkylene alkyl ether sulfonate, from the viewpoint of desorption and reattachment properties. , polyoxyalkylene alkyl ether phosphate, and the like.

(Cationic surfactant)
Examples of cationic surfactants include alkylamine salts and quaternary ammonium salts. Specifically, stearylamine acetate, trimethylyac ammonium chloride, trimethyl tallow ammonium chloride, dimethyldioleyl ammonium chloride, methyloleyl diethanol chloride, tetramethylammonium chloride, laurylpyridinium chloride, laurylpyridinium bromide, laurylpyridinium disulfate, cetylpyridinium bromide. , 4-alkylmercaptopyridine, poly(vinylpyridine)-dodecyl bromide, dodecylbenzyltriethylammonium chloride and the like can be used.

(Amphoteric surfactant)
Examples of amphoteric surfactants include betaine lauryldimethylaminoacetate, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, betaine coconut fatty acid amidopropyldimethylaminoacetate, polyoctylpolyaminoethylglycine, and imidazoline. derivatives.

One of these dynamic surface tension modifiers may be used alone, or two or more thereof may be used in combination. The content of the surfactant in the desorbed liquid is preferably in the range of 0.1 to 10% by mass, more preferably in the range of 0.25 to 5% by mass, based on the total mass of the desorbed liquid. Yes, most preferably 0.5 to 1% by mass. When it is 0.1% by mass or more, it is preferable because it is excellent in removability, and from the viewpoint of foaming, it is preferably 10% by mass or less.

[Basic compound]
Since the desorption liquid used in the present invention has a pH of 13.3 or higher at 25° C., it must contain a basic compound.
The basic compound is not particularly limited, and examples thereof include sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), ammonia, barium hydroxide (Ba(OH) ₂ ), Sodium carbonate _{( Na2CO3} ) is preferably used. At least one of sodium hydroxide and potassium hydroxide is more preferred.

[Antifoaming agent]
An antifoaming agent may be added to the stripping liquid in order to suppress foaming when the dynamic surface tension modifier is added. Antifoaming agents include silicone compounds and non-silicone compounds.

(Silicone-based compound)
Examples of the silicone compound include emulsion type, self-emulsifying type, oil type, oil compound type, and solvent type.

The emulsion type is a silicone antifoaming agent made into an O / W type emulsion by emulsifying a silicone oil compound with an active agent. Examples include “FC2913” and “SILFOAM SE47” manufactured by Wacker Silicone, “BYK-015” and “BYK-1640” manufactured by BYK-Chemie Japan, and “TEGO Foamex 1488” manufactured by Evonik Japan.

The self-emulsifying type is a silicone-based antifoaming agent containing 100% active ingredients that becomes an emulsion state by diluting and mixing with water. , "SILFOAM SD670" and "SILFOAM SD850" manufactured by Asahi Kasei Wacker Silicone.

The oil type is a 100% silicone oil defoaming agent that does not contain solvents or additives. AK12500” and “BYK-1770” manufactured by BYK-Chemie Japan.

The oil compound type is a silicone antifoaming agent in which silica particles are blended with silicone oil. "PULPSIL22274VP", BYK-Chemie Japan's "BYK-017" and "BYK-018" are mentioned.

The solvent type is a silicone antifoaming agent obtained by dissolving silicone oil in a solvent. and "BYK-025".

(Non-silicone compound)
Examples of the non-silicone compounds include fatty acid ester compounds, urea resin compounds, paraffin compounds, polyoxyalkylene glycol compounds, acrylic ester copolymers, ester polymers, ether polymers, and amide polymers. mineral oil emulsified type, polysiloxane adduct, fluorine compound, vinyl polymer, acetylene alcohol, acrylic copolymer, special vinyl polymer, ethylene glycol, higher alcohol (octyl alcohol, cyclohexanol, etc.) be done.

An antifoaming agent may be used individually by 1 type, and may use 2 or more types together. The content of the antifoaming agent in the stripped liquid is preferably in the range of 0.01 to 5% by mass, more preferably in the range of 0.03 to 3% by mass, based on the total mass of the stripped liquid. be. When it is 0.01% by mass or more, it is excellent in defoaming properties, and when it is 5% by mass or less, it is difficult to remain on the surface of the substrate after detachment, and it is excellent in washability.

It has good alkali resistance, and when combined with a dynamic surface tension modifier, it is difficult to reduce the detachability and reattachment properties. It is at least one selected from the group consisting of silicone compounds and non-silicone compounds.

≪Separation and recovery method≫
The separation and recovery method after the desorption step is not particularly limited. For example, when the support and the substrate are made of the same material, they may be collected through a washing process and a drying process without being separated. If the support and base material are different materials, depending on the intended use of the recycled material, it may be recovered without separation. If a single material is to be obtained, specific gravity separation, near-infrared detection, and air jet are combined. After separating by a known separation method, it may be recovered through a washing step or a drying step as necessary.

The release liquid permeates from the end portion of the laminate, contacts the adhesive layer, dissolves or swells, and separates the base material and the adhesive layer. Therefore, in order to proceed with the detachment step efficiently, it is preferable that the laminate is cut or pulverized and the pressure-sensitive adhesive layer is exposed on the cross section when immersed in the detachment liquid. In such a case, the substrate can be detached in a shorter time.

The temperature of the desorption liquid when the laminate is immersed is preferably 25 to 100.degree. C., more preferably 40 to 90.degree. C., and particularly preferably 50 to 80.degree. The immersion time in the desorbing solution is preferably 1 minute to 24 hours, more preferably 3 minutes to 6 hours, and preferably 5 minutes to 4 hours. The amount of the desorption liquid used is preferably 5 to 100,000 times, more preferably 10 to 10,000 times the mass of the laminate. is preferably stirred or circulated. The rotation speed is preferably 80-5000 rpm, more preferably 80-4000 rpm.

After detaching and recovering the base material from the laminate, the obtained base material is washed with water and dried, and if necessary, the support and the base material are separated to obtain a recycled base material. The removal rate of the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer and the support on the surface of the substrate is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% with respect to the area of the pressure-sensitive adhesive sheet before removal. That's it.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples. In the examples, "parts" means "mass parts", and "%" means "% by mass".
In addition, the compounding amounts in the table are parts by mass, and values other than water and solvent are non-volatile content conversion values. A blank column in the table indicates that it was not blended.

The acid value of the acrylic copolymer was measured by the following method.
<Measurement of acid value>
Accurately weigh 1 g of acrylic copolymer into a stoppered Erlenmeyer flask, add 100 ml of water or toluene/ethanol (volume ratio: toluene/ethanol = 2/1) mixed solution and dissolve, then 0.1N-alcohol. It was titrated with an aqueous potassium hydroxide solution. The acid value (unit: mgKOH/g) was determined by the following formula. In addition, the acid value was the numerical value of the dried sample.
Acid value = {(5.61 × a × F) / S} / (non-volatile content / 100)
S: Sample collection amount (g)
a: consumption of 0.1N-alcoholic potassium hydroxide solution (ml)
F: Factor of 0.1N-alcoholic potassium hydroxide solution

<Production of adhesive composition>
[Production Example 1-1] (Production of adhesive composition (A-1))
0.1 part of tert-dodecylmercaptan as a chain transfer agent was dissolved in 85 parts of n-butyl acrylate and 15 parts of methacrylic acid. Further, 6.7 parts of Newcol 707SF (aqueous solution of polyoxyethylene polycyclic phenyl ether sulfate salt, active ingredient 30%, manufactured by Nippon Nyukazai Co., Ltd.) as an anionic surfactant, and 5% aqueous ammonium persulfate solution as an initiator. After dissolving 6 parts in 35 parts of deionized water, the solution was added and stirred to obtain an emulsion. This was placed in the dropping funnel.
A four-necked flask equipped with a stirrer, condenser, thermometer and the dropping funnel was charged with 72.5 parts of deionized water, the air inside the flask was replaced with nitrogen gas, and the internal temperature was raised to 80°C while stirring. and added 2.4 parts of a 5% ammonium persulfate aqueous solution. After 5 minutes, the emulsion was dropped from the dropping funnel over 3 hours.
While keeping the internal temperature at 80° C., the mixture was aged at 80° C. for 4 hours while stirring, and then cooled to obtain an acrylic copolymer aqueous dispersion. To this aqueous dispersion, 0.3 parts of Adecanate B-940 (manufactured by ADEKA) as an antifoaming agent, 0.2 parts of Pelex OT-P (manufactured by Kao Corporation) as a leveling agent, and Lebanax FX-360 (Shoei) as a preservative. Chemical Co., Ltd.) 0.05 part was added, and the pH was adjusted (measured with a Horiba pH meter D-52) and the viscosity was adjusted with an alkali thickener and ammonia water to obtain a pH of 8.0 and a viscosity of 2,000 mPa (BL A pressure-sensitive adhesive composition (A-1) with a type viscometer #4-12 rpm) was obtained.

[Production Example 1-2] (Production of adhesive composition (A-2))
A pressure-sensitive adhesive composition (A-2) was obtained in the same manner as in [Production Example 1-1], except that the types and blending amounts of the monomer, surfactant, and initiator were changed as shown in Table 1.

[Production Example 1-3] (Production of adhesive composition (A-3))
94.9 parts of n-butyl acrylate, 0.1 part of 2-hydroxyethyl acrylate, 5 parts of acrylic acid and acetic acid were placed in a four-necked flask equipped with a stirrer, condenser, thermometer and the dropping funnel under a nitrogen atmosphere. 100 parts of ethyl and 0.015 parts of 2,2'-azobisisobutyronitrile were charged. The mixture was heated while stirring, and after confirming the initiation of the polymerization reaction, the reaction was carried out at the reflux temperature for 2 hours. Then, 0.005 part of 2,2'-azobisisobutyronitrile was added to the reaction solution and the reaction was continued for 6 hours. After that, the reactor was cooled and 130 parts of ethyl acetate was added to obtain an acrylic copolymer solution. Immediately before preparing the pressure-sensitive adhesive sheet of Production Example 3-3, 0.5 part of aluminum chelate A (manufactured by Kawaken Fine Chemicals Co., Ltd., aluminum trisacetylacetonate) was added as a curing agent, and ethyl acetate was added as a solvent to adjust the non-volatile content to 30. % to obtain an adhesive composition (A-3).

[Production Examples 1-4, 5] (Production of adhesive composition (A-4, 5))
PSA compositions (A-4 to A-5) were obtained in the same manner as in [Production Example 1-3] except that the types and blending amounts of the monomer, initiator and curing agent were changed as shown in Table 1. However, the curing agent was blended immediately before preparing the pressure-sensitive adhesive sheets of Production Examples 3-4 and 3-5.

Abbreviations in Table 1 are listed below.
2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate MA: methyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate MAA: methacrylic acid AA: acrylic acid 707SF; Aqueous solution of ring phenyl ether sulfate, active ingredient 30%)
KH-10: Daiichi Kogyo Seiyaku Co., Ltd., Aqualon KH-10 ((polyoxyethylene-1-(allyloxymethyl)alkyl ether sulfate ester ammonium salt)
APS: ammonium persulfate AIBN: 2,2′-azobisisobutyronitrile Aluminum chelate A: manufactured by Kawaken Fine Chemicals, aluminum chelate A (aluminum trisacetylacetonate)
TDI/TMP: Trimethylolpropane adduct of tolylene diisocyanate (37.5% non-volatile content)

<Support>
[Production Example 2-1] (Production of support (B-2))
237.8 parts of water and 0.86 parts of Pelex OT-P (manufactured by Kao Corporation, sodium dioctyl sulfosuccinate, active ingredient 70%) were placed in a reaction vessel (reaction tank) equipped with a stirrer, thermometer, dropping funnel, and reflux device. planted. Separately, 69.5 parts of methyl methacrylate, 18.0 parts of n-butyl acrylate, 12.5 parts of methacrylic acid, 3.0 parts of t-dodecyl mercaptan, 2.01 parts of Pelex OT-P, and 65.8 parts of water. An ethylenically unsaturated monomer emulsified liquid (first-stage dropping vessel) was prepared by mixing and stirring in advance to be dropped in the first stage. After the internal temperature of the reaction vessel was raised to 80° C. and the contents were sufficiently replaced with nitrogen, 12.1 parts of a 5% aqueous solution of potassium persulfate was added as an initiator to initiate emulsion polymerization. While maintaining the internal temperature at 80° C., the ethylenically unsaturated monomer emulsion and 5.5 parts of a 5% potassium persulfate aqueous solution were added dropwise over 2 hours. After the dropwise addition was completed, the mixture was reacted for 2 hours, and neutralized by adding 9.9 parts of 25% aqueous ammonia while maintaining the temperature at 80°C. Subsequently, 50.0 parts of methyl acrylate and 102.0 parts of n-butyl acrylate were mixed in advance to prepare a second-stage ethylenically unsaturated monomer solution (second-stage dropping tank) and 10 parts of ammonium persulfate. % aqueous solution was added dropwise over 2 hours. After the dropping was completed, the mixture was allowed to react for another 3 hours while maintaining the temperature at 80° C. to obtain an aqueous dispersion of fine resin particles. The acid value of the obtained resin fine particles was 31.2 mgKOH/g. Water was further added to this to adjust the non-volatile content to 40%, thereby obtaining a filler for non-woven fabric.
Polyethylene terephthalate non-woven fabric MF-90 (support (B-1), Gurley air permeability of 0.1 second) manufactured by Japan Vilene Co., Ltd. was pressed against a metal roll using a pressure nip device consisting of a metal roll and an elastic roll. After calendering at a surface temperature of 195° C., a nip pressure of 100 kN/m, and a processing speed of 10 m/min, the filling agent was applied with a gravure coater so that the coating amount after drying was 3 g/m ² , and 80° C. 120 Air dried for seconds. The resulting filler treated polyethylene nonwoven fabric (support (B-2)) had a Gurley air permeability of 15 sec/100 ml.

[Production Example 2-2] (Production of support (B-3))
A solution consisting of a high-density polyethylene polymer (melt mass flow rate (hereinafter referred to as “MFR”) = 0.8) and HFC refrigerant R32 is discharged from a nozzle to a low-temperature and low-pressure region from a high-temperature and high-pressure condition to flash the solvent to obtain gold. After depositing in a net shape to form a fibrillated net fiber, both sides were treated with a felt calender at 138° C. for a contact time of 5 seconds to obtain a polyethylene nonwoven fabric. The Gurley air permeability of the obtained nonwoven fabric (support (B-3)) was 4 seconds/100 ml.
The MFR was measured according to JIS K7210-1:2014 at a temperature of 230° C. and a load of 2.16 kgf (21.2 N).

[Production Example 2-3] (Production of support (B-4))
The filling agent obtained in Production Example 2-1 was applied to the support B-3 obtained in Production Example 2-2 with a gravure coater so that the coating amount after drying was 3 g/m ² . It was air-dried at °C for 120 seconds. The resulting filler-treated polyethylene nonwoven fabric (support (B-4)) had a Gurley air permeability of 11 sec/100 ml.

[Production Example 2-4] (Production of support (B-6))
The filling agent obtained in Production Example 2-1 was dried on a polyethylene non-woven fabric Tyvek 1-73B (support (B-5), Gurley air permeability 22 seconds/100 ml) manufactured by Asahi-DuPont Flashspun Products Co., Ltd. It was applied with a gravure coater so that the subsequent coating amount was 3 g/m ² and air-dried at 80° C. for 120 seconds. The resulting filler-treated polyethylene nonwoven fabric (support (B-6)) had a Gurley air permeability of 45 seconds/100 ml.

[Production Example 2-5] (Production of support (B-7))
The support (B-5) was calendered using a pressure nip device consisting of a metal roll and an elastic roll at a metal roll surface temperature of 130° C., a nip pressure of 100 kN/m, and a processing speed of 10 m/min. The obtained nonwoven fabric (support (B-7)) had a Gurley air permeability of 150 sec/100 ml.

[Production Example 2-6] (Production of support (B-8))
The support (B-5) was calendered using a pressure nip device consisting of a metal roll and an elastic roll at a metal roll surface temperature of 140° C., a nip pressure of 100 kN/m, and a processing speed of 5 m/min. The resulting nonwoven fabric (support (B-8)) had a Gurley air permeability of 500 sec/100 ml.

[Production Example 2-7] (Production of support (B-10))
A polypropylene non-woven fabric Syntex (support (B-9), Gurley air permeability 180 seconds/100 ml) manufactured by Mitsui Chemicals, Inc. was subjected to a surface temperature of 130 using a pressure nip device consisting of a metal roll and an elastic roll. ℃, a nip pressure of 100 kN/m, and a processing speed of 10 m/min. The resulting nonwoven fabric (support (B-10)) had a Gurley air permeability of 450 sec/100 ml.

[Production Example 2-8] (Production of support (B-11))
The filling agent obtained in Production Example 2-1 was applied to the support (B-9) with a gravure coater so that the coating amount after drying was 3 g/m ² and air-dried at 80° C. for 120 seconds. The obtained nonwoven fabric (support (B-11)) had a Gurley air permeability of 720 sec/100 ml.

[Production Example 2-9] (Production of support (B-12))
94.6 parts of FS2016 manufactured by Sumitomo Chemical Co., Ltd. and 5 parts of HMS-PP manufactured by SunAllomer Co., Ltd. as polypropylene resins, and N,N'-dicyclohexyl-2,6-naphthalene dicarboxamide (Shin Nippon Rika Co., Ltd.) as β crystal nucleating agent NU-100 manufactured by 0.2 parts of the company and 0.2 parts of cross-linked PMMA particles (Eposter MA1002 manufactured by Nippon Shokubai Co., Ltd.) as a slip agent were added and mixed, supplied to a twin-screw extruder, and melt-mixed at 200°C. Then, it was extruded into a gut shape, cooled in a water bath at 20°C, cut into 3 mm lengths with a tip cutter, and dried at 100°C for 2 hours. Next, it is supplied to an extruder heated to 200° C., melted, extruded into a sheet through a T-die mouthpiece, adhered to a cast drum heated to a surface temperature of 120° C., and pressed from the non-drum surface side. Hot air at 120° C. was blown to cool and solidify to produce an unstretched film. The unstretched film was introduced into an oven heated and maintained at 100°C, preheated, stretched 6 times in the MD direction, and cooled with rolls at 40°C. Subsequently, while holding both ends of the film stretched in the MD direction, it was guided to a tenter, and after being stretched 9 times in the TD direction in an atmosphere heated to 125 ° C. (area ratio: longitudinal stretch ratio × transverse stretch ratio = 54 times ), followed by a relaxation heat treatment of 5% in the transverse direction at 150 ° C. in a tenter in order to complete the crystal orientation of the microporous polypropylene film and to impart planarity and dimensional stability. to obtain a microporous polypropylene film (support (B-12)). The obtained support (B-12) had a Gurley air permeability of 80 seconds/100 ml.

[Production Example 2-10] (Production of support (B-13))
The filler obtained in Production Example 2-1 was applied to the support (B-7) with a gravure coater so that the coating amount after drying was 3 g/m ² and air-dried at 80° C. for 120 seconds. The obtained nonwoven fabric (support (B-13)) had a Gurley air permeability of 1300 sec/100 ml.

Table 2 summarizes the Gurley air permeability of each support.

<Production of adhesive sheet>
[Production Example 3-1] (Production of adhesive sheet (C-1))
The pressure-sensitive adhesive composition (A-1) is applied onto the release sheet using a comma coater, dried in a drying oven at 100° C. for 120 seconds, and then laminated to the support (B-5) for adhesion. A sheet (C-1) was obtained. The amount of adhesive applied was 26.2 g/m ² .

[Production Examples 3-2 to 21] (Production of adhesive sheets (C-2 to 21))
Adhesive sheets (C-2 to C-21) were obtained in the same manner as in [Production Example 3-1] except that the composition and blending amount were changed as shown in Table 3. However, the contents of supports (B-1), (B-5), (B-9), (B-14) and support (B-15) are as follows.
Support (B-1): Polyethylene terephthalate non-woven fabric MF-90 manufactured by Japan Vilene Co., Ltd. (Support (B-1), Gurley air permeability 0.1 sec/100 ml)
Support (B-5): Polyethylene non-woven fabric Tyvek 1-73B manufactured by Asahi DuPont Flashspun Products Co., Ltd. (Support (B-5), Gurley air permeability 22 seconds/100 ml)
Support (B-9): Polypropylene non-woven fabric Syntex manufactured by Mitsui Chemicals, Inc. (Support (B-9), Gurley air permeability 180 seconds/100 ml)
Support (B-14): commercially available glassine paper (Gurley air permeability 15 sec/100 ml)
Support (B-15): commercially available polyethylene film (thickness 25 μm, Gurley air permeability 1300 seconds/100 ml or more)

<Production of desorbed liquid>
[Production Example 4-1] (Production of elimination liquid (D-1))
As surfactants, 0.25 parts of Emulgen A-60 manufactured by Kao Corporation, 2 parts of sodium hydroxide, and 97.75 parts of water were blended and stirred with a disper to obtain an elimination liquid (D-1).

[Production Examples 4-2 to 18] (Production of desorbed solutions (D-2 to 18))
Elimination liquids (D-2 to D-18) were obtained in the same manner as in [Production Example 4-1] except that the composition and blending amount were changed as shown in Table 4.

In Table 4, Lipocard 16-29 is manufactured by Lion Specialty Chemicals Co., Ltd., and other surfactants are manufactured by Kao Corporation.

[Example 1]
Laminates were produced and detachability evaluations were carried out by the following methods. In addition, the waterproof adhesive strength of the laminate was also measured.
[Production of laminate]
At 23 ° C., in an atmosphere of 50% relative humidity, each adhesive sheet (C-1) produced in Production Example 3-1 was cut into 25 mm × 100 mm, and the adhesive layer exposed by peeling off the release sheet was used as a base material (polyethylene film , 30 mm×120 mm, thickness 50 μm), and press-bonded once with a 2-kg roll to obtain a laminate.

[Water resistance adhesive strength]
A 25 mm×20 mm end portion of the adhesive sheet was peeled off from the laminate, and then folded inward by about 10 mm to attach the adhesive layers to each other. After immersing this in ion-exchanged water for 20 minutes, remove the sample from the ion-exchanged water, drain the surface water, reinforce the substrate side with a SUS plate, and measure the adhesive force in accordance with JIS Z 0237: 2009. The obtained value was taken as the waterproof adhesive strength.
It was determined that if the water-resistant adhesive strength is 300 gf/25 mm or more, it is possible to prevent water immersion peeling when frost or dew condensation occurs.

(Removability evaluation)
400 g of desorbing liquid (D-4) and 12 g of a 1 cm×1 cm sample of the laminate were placed in a 1000 mL stainless steel beaker and stirred at 80° C. and 2000 rpm. The detached base material floating near the surface of the treatment liquid was scooped, washed with water, and dried to separate and recover the base material.

In the separation and recovery test, 10 substrates were recovered after 15 minutes, 30 minutes, and 1 hour from the start of stirring, washed with water, and dried. The presence or absence of absorption peaks of the adhesive was confirmed using FT-IR for a total of 30 locations, 3 locations on the front and back sides of the base material, and evaluated according to the following criteria.
A (very good): Less than 5 locations where absorption peaks of the pressure-sensitive adhesive layer were observed in the base material collected 15 minutes after the start of stirring.
B (excellent): In the base material collected 30 minutes after the start of stirring, the number of locations where absorption peaks of the pressure-sensitive adhesive layer were confirmed for the first time is less than 5 locations.
C (Practical): In the base material collected 1 hour after the start of stirring, the absorption peak of the pressure-sensitive adhesive layer was confirmed for the first time at less than 5 locations.
D (impossible to use): 6 or more locations where the absorption peak of the pressure-sensitive adhesive layer was confirmed in the base material recovered 1 hour after the start of stirring.

[Examples 2 to 34, Comparative Examples 1 to 8]
A separation and recovery test was conducted in the same manner as in Example 1, except that the base material and adhesive sheet of the laminate, and the release liquid were changed to those shown in Table 5, and the release performance was evaluated. However, in Comparative Example 3, the difference between the support and the substrate was determined by the thickness.
In Comparative Example 2, no absorption peak of the pressure-sensitive adhesive layer was observed in 10 substrates collected 15 minutes after the start of stirring. It was judged that it was not practical because it took a long time to wash with water. Comparative Examples 7 and 8 were at a level such that they were peeled off before the start of the measurement of the waterproof adhesive strength, so the detachability test could not be carried out.

The substrates in Table 5 are described below.
PET: polyethylene terephthalate film, thickness 200 μm
PE: polyethylene film, thickness 50 μm
PP: Polypropylene film, thickness 50 μm

From the above evaluation results, it is possible to efficiently separate and recover the substrate from the laminate in which the pressure-sensitive adhesive sheet having water-resistant adhesive strength and the substrate are bonded together by the method for separating and recovering the laminate of the present invention.

Claims (3)

A method for separating and recovering a substrate from a laminate in which a support, an adhesive layer and a substrate are laminated in this order,
The support is a nonwoven fabric or a breathable film (excluding base paper) having a Gurley air permeability of 10 to 1000 sec/100 ml,
including a step of immersing the laminate in a detachment liquid to detach the substrate from the adhesive layer, wherein the detachment liquid has a pH of 13.3 or higher at 25°C;
And the dynamic surface tension of the desorbed liquid at 1000 msec measured at 25 ° C. is 60 mN / m or less,
A method for separating and recovering a base material. The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer containing an acrylic copolymer, the acrylic copolymer is a copolymer of a monomer mixture containing a (meth)acrylate having a carboxyl group, and the acrylic copolymer 2. The method for separating and recovering a substrate according to claim 1, wherein the polymer has an acid value of 0.1 to 100 mgKOH/g. 3. The method for separating and recovering a substrate according to claim 1, wherein the coating amount of the adhesive layer is 10 to 30 g/m ² .