JP2024016444A - Method for separating and recovering base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for separating and recovering a base, where the method is suitable for plastic recycling and, even when used for a laminate obtained by bonding a base and a pressure-sensitive adhesive sheet together, the sheet comprising a support and a pressure-sensitive adhesive layer applied in an amount of 10-100 g/m², realizes excellent removability of the pressure-sensitive adhesive sheet while inhibiting the removed components from re-adhering.

SOLUTION: A method for separating and recovering a base includes a step in which a laminate is immersed in remover liquid to remove a pressure-sensitive adhesive sheet, where the remover liquid contains a basic compound, a surfactant having an HLB of 7 or more, and a defoaming agent.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a method for separating and recovering a base material.

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 increasing, and the disposal of waste has become an important environmental issue.
Examples of the above-mentioned plastic products include food packaging packages using plastic films, and such food packaging packages may have a sheet containing an adhesive layer attached to form a laminate. Such multi-layered food packaging packages contain a mixture of different types of materials, so there is a problem in that they cannot be recycled as they are.
Regarding the material recycling of such multi-layer packaging materials, for example, Patent Document 1 describes that a laminate including an adhesive layer containing a polyurethane resin having a predetermined acid value is treated with an alkaline aqueous solution to remove the adhesive. Techniques have been disclosed in which layers and the like are separated and the base material is separated and recovered.
Further, Patent Document 2 discloses a technique for removing ink from a film using a cleaning solution that has a basic pH and contains a cationic or anionic surfactant.

JP2020-090627A Special table 2015-520684 publication

However, in the desorption process described in Patent Document 1, when the amount of the packaging material treated with the alkaline aqueous solution is increased in order to improve productivity, the desorption performance decreases and furthermore, the desorbed components are finely dispersed. This poses a problem in that it re-adheres to the plastic base material. Molding materials obtained by recycling such base materials suffer from deterioration in appearance and physical properties due to foreign matter.
Furthermore, when the desorption liquid contains the surfactant described in Patent Document 2, bubbles are generated in the desorption step. The generated bubbles trap components (particularly highly lipophilic components) eluted from the adhesive layer, form micelles, and float to the surface of the desorption liquid. On the other hand, when a base material with a low specific gravity is used, it similarly floats to the surface of the desorbed liquid, so the desorbed components and the base material crowd together on the surface of the desorbed liquid, and are further re-released to the base material. There is a problem that adhesion deteriorates.
Furthermore, packaging materials such as food trays require strong adhesive strength to the base material in order to prevent price tag stickers and the like from being removed artificially. Therefore, the amount of adhesive layer applied is generally 10 to 100 g/ ^m2 , but when recycling packaging materials with such a relatively thick adhesive layer, the above problems tend to become even more pronounced. There is.
Therefore, an object of the present invention is to provide excellent removability of the adhesive sheet even in a laminate in which a base material is laminated to an adhesive sheet having an adhesive layer with a coating amount of 10 to 100 g/m ² . It is an object of the present invention to provide a method for separating and recovering base materials suitable for plastic recycling, in which re-adhesion of separated components is suppressed.

In a method for separating and recovering a base material according to one embodiment of the present invention, a laminate in which a base material and a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer and a support with a coating amount of 10 to 100 g/m ² are bonded together is coated with a basic compound. The adhesive sheet is characterized by including a step of immersing the pressure-sensitive adhesive sheet in a desorption liquid containing a surfactant and an antifoaming agent having an HLB value of 7 or more to desorb the pressure-sensitive adhesive sheet.
In the method for separating and recovering a base material according to one aspect of the present invention, the antifoaming agent is at least one selected from the group consisting of an emulsion-type silicone compound, a self-emulsifying silicone compound, and a non-silicone compound. It is characterized by
The method for separating and recovering a substrate according to one aspect of the present invention is characterized in that the surfactant includes at least one of a nonionic surfactant and an anionic surfactant.
In the method for separating and recovering a base material according to one aspect of the present invention, the adhesive layer includes an acrylic copolymer, and the acrylic copolymer is a copolymer of a monomer mixture containing a (meth)acrylate having a carboxyl group. The acrylic copolymer is characterized by having an acid value of 0.1 to 150 mgKOH/g.

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a method for separating and recovering a base material suitable for plastic recycling, which has excellent removability of a pressure-sensitive adhesive sheet, and further suppresses redeposition of desorbed components.

The present invention will be explained in detail below. It goes without saying that other embodiments are also included in the scope of the present invention as long as they meet the spirit of the present invention. Further, in this specification, a numerical range specified using "~" includes the numerical values written before and after "~" as the lower limit value and upper limit value range.
Before describing the present invention in detail, some terms will be defined. (Meth)acrylic acid includes acrylic acid and methacrylic acid. (Meth)acrylate includes acrylate and methacrylate. The monomer is a monomer having ethylenically unsaturated double bonds.
Unless otherwise noted, the various components appearing in this specification may be used individually or in combination of two or more.

The present invention includes a step of immersing a laminate in which a base material and a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer and a support with a coating weight of 10 to 100 g/m ² are bonded together in a release liquid to release the pressure-sensitive adhesive sheet. A method for separating and recovering a base material, comprising: a desorbing liquid containing a basic compound, a surfactant having an HLB value of 7 or more, and an antifoaming agent.
The release liquid contains a basic compound and a surfactant with an HLB value of 7 or more, thereby promoting the release of the adhesive sheet, and further contains a release component (for example, an adhesive derived from the adhesive layer). Since it is possible to suppress redeposition of components) to the base material from which they have been removed, clean base materials can be recovered.
Antifoaming agents can suppress foam generated by surfactants during the desorption process, but antifoaming agents are generally extremely lipophilic and have a small HLB value of about 1 to 3, so the HLB value is low. Contrary to surfactants of 7 or more, they tend to reduce the releasability.
However, by using a combination of a surfactant with an HLB value of 7 or more and an antifoaming agent, the present application provides excellent desorption and reattachment properties even when the amount of the laminate relative to the desorption liquid is increased. It is possible to achieve both. This is due to the fact that the generation of bubbles is suppressed, and the antifoaming agent in the desorption liquid has an affinity with the components desorbed from the adhesive layer and is in a stable state. It is presumed that it exhibits excellent reattachment properties without impairing the improvement.

<Separation and recovery method>
The separation and recovery method of the base material of the present invention is to prepare ^a laminate in which a base material and a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer and a support with a coating amount of 10 to 100 g/m 2 are bonded together. The method includes a step of immersing the adhesive sheet in a desorption liquid containing 7 or more surfactants and an antifoaming agent to desorb the pressure-sensitive adhesive sheet.
In the present invention, "detachment" refers to the desorption of the adhesive sheet base material from the laminate as the adhesive layer dissolves or swells with a desorption liquid and peels off. This includes both the case where the adhesive layer is released and the case where the adhesive layer is peeled off and detached by neutralization, swelling, etc. even if it does not dissolve.

Since the purpose of the present invention is to obtain the base material after the adhesive sheet has been removed as a recycled base material or recycled base material, it is preferable to remove as much of the adhesive sheet as possible from the base material. Specifically, the removal rate of the adhesive sheet having the adhesive layer and the support on the surface of the base material is preferably 70% or more, more preferably 80% or more, based on the area of the adhesive sheet before detachment. Particularly preferably, it is 90% or more.
The substrate recovery step after being immersed in a desorption solution and detached from the adhesive sheet can be freely selected depending on the material of the support material and the substrate, such as specific gravity separation or size separation.

<Desorption liquid>
The desorption liquid may contain a basic compound, a surfactant with an HLB value of 7 or more, and an antifoaming agent, and can swell and dissolve the adhesive layer. From the viewpoint of maintaining the properties of the recycled material using the base material, an aqueous solution is preferable. These desorption liquids may be heated.

[Basic compound]
As mentioned above, the desorption solution used in the present invention needs to contain a basic compound.
The basic compound is not particularly limited, and examples include sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), ammonia, barium hydroxide (Ba(OH) ₂ ), Sodium carbonate (Na ₂ CO ₃ ) is preferably used. More preferably, at least one of sodium hydroxide and potassium hydroxide is used.

The content of the basic compound in the desorption solution is preferably 0.5 to 20% by mass, more preferably 1 to 15% by mass, even more preferably 2 to 15% by mass, based on the mass of the desorption solution. range. Within the above range, the release liquid can maintain sufficient basicity to remove the adhesive sheet and recover the base material by dissolving or swelling the adhesive layer, which will be described later.

[Surfactant with HLB value of 7 or more]
A surfactant having an HLB value of 7 or more mainly plays a role in improving the releasability of the pressure-sensitive adhesive sheet. This is thought to be because the action of the surfactant with an HLB value of 7 or more lowers the surface tension of the release liquid, making it easier to penetrate into the adhesive layer and promoting release properties. Further, it is thought that the adsorption of a surfactant having an HLB value of 7 or more on the surface of the released component and the base material prevents the adhesive component from re-adhering.

Furthermore, when the amount of the laminate relative to the desorbing liquid is increased during separation and recovery, the laminate and the separated base material tend to curl while enveloping the desorbed adhesive sheet. However, it is difficult to cleanly remove the adhesive layer and the like. However, since the desorption liquid contains a surfactant having an HLB value of 7 or more, the surfactant is adsorbed to the surface of the laminate and the separated base material, and curling is suppressed. As a result, detachability is improved and re-adhesion can be suppressed.

The HLB value is an index value related to the affinity of surfactants for water and oil, and is divided into equal parts, with the HLB value of substances without hydrophilic groups being 0 and the HLB value of substances having only hydrophilic groups being 20. be. The concept of HLB was proposed by William Griffin of the Atlas Powder Company in 1949, and several methods for determining it by calculation have been proposed. In the present invention, the HLB value can be determined from the following equation using the Griffin method.
Formula) HLB=20×[(molecular weight of hydrophilic group contained in surfactant)/(molecular weight of surfactant)]

Examples of the hydrophilic group contained in the surfactant include a hydroxyl group and an ethyleneoxy group.

It is important that the HLB value of the surfactant in the present invention is 7 or more. When the HLB is 7 or more, excellent detachability and reattachment properties are exhibited as described above. The HLB value of the surfactant is preferably 8 or more, more preferably 10 or more. Further, the HLB value of the surfactant is preferably 20 or less, more preferably 19 or less, and still more preferably 17 or less. It is preferable that the HLB value is 20 or less because it has excellent antifoaming properties.

Types of surfactants with an HLB value of 7 or more include, for example, nonionic, anionic, cationic, and amphoteric surfactants, and suitable types and amounts can be selected and used according to the required properties. can. From the viewpoint of detachability and foamability, it is preferable that at least one of a nonionic surfactant and an anionic surfactant is included.
Further, the surfactant preferably has a structure in which alkylene oxide (hereinafter also referred to as AO) is added, since this improves detachability and reattachment properties.

(Nonionic surfactant)
The nonionic surfactant is not particularly limited as long as it has an HLB value of 7 or more, but is preferably an alkylene oxide adduct to which alkylene oxide is added. 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 alkylene oxide to fatty acids (fatty acid nonionic surfactant). The above addition may be either random addition or block addition. Further, the alkylene oxide preferably has 2 to 4 carbon atoms.
More preferred nonionic surfactants are alcohol-based nonionic surfactants obtained by adding an alkylene oxide having 2 to 4 carbon atoms to an alcohol.

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

[Amine-based nonionic surfactant]
Examples of 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. Examples of amines include 2-ethylhexylamine, di2-ethylhexylamine, laurylamine, dilaurylamine, tetradecylamine, ditetradecylamine, hexadecylamine, dihexadecylamine, stearylamine, distearylamine, oleylamine, di- Examples include oleylamine. Further, the type of alkylene oxide and the number of moles added are the same as those described in the section of [Alcoholic nonionic surfactant] mentioned above.

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

(Anionic surfactant)
The anionic surfactant having an HLB value of 7 or more is preferably a non-soap type, such as a sulfonic acid-based anionic surfactant, a sulfuric acid ester-based anionic surfactant, a carboxylic acid-based anionic surfactant, or a phosphoric acid-based anionic surfactant. Examples include acid ester anionic surfactants.
[Sulfonic acid-based anionic surfactant]
Examples of the sulfonic acid-based anionic surfactants include alkylsulfonic acids, alkylbenzenesulfonic acids, alkylnaphthalenesulfonic acids, alkyldiphenyl ether disulfonic acids, alkylmethyltaurine, sulfosuccinic acid diesters, alkylene oxide adducts of sulfonic acids, and these. Examples include salt. Specific examples include hexane sulfonic acid, octanesulfonic acid, decane sulfonic acid, dodecane sulfonic acid, toluene sulfonic acid, cumene sulfonic acid, octylbenzenesulfonic acid, dodecylbenzenesulfonic acid, dinitrobenzenesulfonic acid, and lauryl dodecylphenyl ether disulfone. An acid etc. can be used.

[Sulfate ester anionic surfactant]
Examples of the sulfate-based anionic surfactant include sulfuric esters (alkyl ether sulfuric esters), alkylene oxide adducts of sulfuric esters, and salts thereof. Specific examples include lauryl sulfate, myristyl sulfate, and polyoxyethylene lauryl ether sulfate.

[Carboxylic acid-based anionic surfactant]
Examples of the carboxylic acid-based anionic surfactant include alkyl carboxylic acids, alkylbenzene carboxylic 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-based anionic surfactant]
Examples of the phosphoric ester-based anionic surfactant include phosphoric esters (alkyl ether phosphates), alkylene oxide adducts of phosphoric 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 having an HLB value of 7 or more preferably has an alkyl group having 2 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, and more preferably has an alkyl group having 8 to 18 carbon atoms. It is something. The alkyl group or alkenyl group may be linear or branched.

Further, when the anionic surfactant having an HLB value of 7 or more 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 added is preferably 1 to 12 moles, more preferably 1 to 8 moles, per mole of alcohol or alkylphenol. It is preferable that the content is within the above range because it has particularly excellent releasability.

Examples of the salt constituting the above-mentioned anionic surfactant include metal salts such as sodium, potassium, magnesium, and calcium. These salts may be used alone or in combination of two or more.
Among them, preferred anionic surfactants are sulfonate type and phosphate type from the viewpoint of detachability and reattachment property, and more preferred are alkyl sulfonates and polyoxyalkylene alkyl ether sulfonates. , polyoxyalkylene alkyl ether phosphate, and the like.

(Cationic surfactant)
Examples of the cationic surfactant having an HLB value of 7 or more include alkylamine salts and quaternary ammonium salts. Specifically, stearylamine acetate, trimethylyacyanmonium chloride, trimethyltallow ammonium chloride, dimethyldioleylammonium chloride, methyloleyldiethanol 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.

(Ampholytic surfactant)
Examples of amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, and imidazoline. Examples include derivatives.

These surfactants having an HLB value of 7 or more may be used alone or in combination of two or more. The content of the surfactant having an HLB value of 7 or more in the desorption solution is preferably in the range of 0.1 to 10% by mass, more preferably 0.3 to 5% by mass, based on the mass of the desorption solution. It is in the range of % by mass. It is preferable that the content is 0.1% by mass or more because it has excellent detachability and reattachment property, and it is preferable that it is 10% by mass or less from the viewpoint of antifoaming properties.

[Defoaming agent]
By using the antifoaming agent in combination with the above-mentioned surfactant with an HLB value of 7 or more, it exhibits good antifoaming properties without reducing the detachability and reattachment properties, and the foaming caused by the surfactant is suppressed. Can be suppressed.
Examples of the antifoaming agent include silicone compounds and non-silicone compounds.

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

Emulsion type is a silicone antifoaming agent that emulsifies a silicone oil compound with an activator to form an O/W type emulsion.For example, "KM-89" and "KM-98" manufactured by Shin-Etsu Chemical, 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.

Self-emulsifying type antifoaming agents are silicone antifoaming agents with 100% active ingredients that become an emulsion when diluted with water and mixed.For example, "KS-540" and "X-50-1176" manufactured by Shin-Etsu Chemical Co., Ltd. , "SILFOAM SD670" and "SILFOAM SD850" manufactured by Asahi Kasei Wacker Silicone.

The oil type is a 100% silicone oil antifoaming 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 made by blending silica particles with silicone oil, such as "KM-89" and "KM-98" manufactured by Shin-Etsu Chemical, "SILFOAM SC370" manufactured by Asahi Kasei Wacker Silicone, Examples include "PULPSIL22274VP" and "BYK-017" and "BYK-018" manufactured by BYK Chemie Japan.

Solvent type is a silicone antifoaming agent made by dissolving silicone oil in a solvent, such as "KM-89" and "KM-98" manufactured by Shin-Etsu Chemical, "BYK-019" manufactured by BYK Chemie Japan, "BYK-025" is an example.

(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. Examples include emulsified types of mineral oil, polysiloxane adducts, fluorine compounds, vinyl polymers, acetylene alcohol, acrylic copolymers, special vinyl polymers, ethylene glycol, and higher alcohols (octyl alcohol, cyclohexanol, etc.). It will be done.

The antifoaming agents may be used alone or in combination of two or more. The content of the antifoaming agent in the desorption solution 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 mass of the desorption solution. . When it is 0.01% by mass or more, antifoaming properties are excellent, and when it is 5% by mass or less, it is excellent in detachability and reattachment properties.

Preferably, emulsion-type silicone compounds and self-emulsifying antifoaming agents have good alkali resistance and are less likely to reduce detachment and re-deposition when combined with the above-mentioned surfactants with an HLB of 7 or higher. At least one type selected from the group consisting of type silicone compounds and non-silicone compounds.

The desorption liquid permeates through the end portion of the laminate, contacts the adhesive layer, and dissolves or swells, thereby separating the base material and the adhesive layer. Therefore, in order to proceed with the desorption process efficiently, it is preferable that the laminate is cut or crushed and the adhesive layer is exposed in the cross section when it is immersed in the desorption liquid. In such a case, the adhesive sheet can be removed in a shorter time.

The temperature of the desorption liquid during immersion of the laminate is preferably in the range of 25 to 100°C, more preferably 30 to 100°C, particularly preferably 30 to 90°C. The immersion time in the desorption solution is preferably in the range of 1 minute to 24 hours, more preferably 1 minute to 12 hours, and preferably 1 minute to 6 hours. The amount of desorption liquid to be used is preferably 50,000 to 100,000 times, more preferably 100,000 to 100,000 times the mass of the laminate. It is preferable to perform stirring or circulation. The rotation speed is preferably 80 to 5000 rpm, more preferably 80 to 4000 rpm.

After removing and recovering the adhesive sheet from the laminate, a recycled base material can be obtained through a process of washing and drying the resulting base material.

<Laminated body>
The laminate used in the present invention is made by laminating a base material and a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer and a support with a coating weight of 10 to 100 g/m ² .

(Base material)
Examples of base materials 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, and cellophane resins. Plastic films made of materials, polyethylene nonwoven fabrics, polyester nonwoven fabrics, vinylon nonwoven fabrics, etc. are mentioned. The base material may be a single laminate or a laminate of a plurality of laminates. In addition, on the base material, there is a printed layer for displaying product names, decoration, and giving an aesthetic appearance, and an overcoat layer for protecting the printed layer and adding design properties such as gloss. may be provided. From the viewpoint of removability and recyclability after separation and recovery, it is preferable not to include a printed layer or an overcoat layer.

(adhesive sheet)
The adhesive sheet has an adhesive layer with a coating weight of 10 to 100 g/m ² and a support. The coating amount of the adhesive layer is preferably 10 to 50 g/m ² , more preferably 10 to 25 g/m ² . In the present invention, the adhesive sheet is a release layer that is released from the laminate.

The pressure-sensitive adhesive sheet can be formed by applying the pressure-sensitive adhesive composition described below onto a support and drying it. Alternatively, the adhesive layer can be formed by coating the adhesive composition described below on a release liner and drying to form an adhesive layer, and then bonding the support.

[Support]
Examples of the support include paper, plastic, rubber, foam, fiber, nonwoven fabric, glass, metal, wood, and the like. Among these, paper and plastic are preferred. As the paper support material, for example, high-quality paper, coated paper, thermal paper, etc. can be used. There are also acidic papers and neutral papers, depending on the method of fixing the sizing agent to the paper. Examples of the plastic support material include polyethylene, polypropylene, polyester, and polyimide. The support may be a single material or a laminate. Further, the back surface of the support (the surface opposite to the surface to which the adhesive layer is directly bonded) can be subjected to a release treatment or an antistatic treatment. The thickness of the support is generally 10 μm to 200 μm, preferably 20 μm to 80 μm.

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

[Coating method]
Coating can be done by any known method, such as a comma coater, reverse coater, slot die coater, lip coater, gravure chamber coater, curtain coater, etc., on the support or release liner. The pressure-sensitive adhesive sheet of the present invention can be obtained by coating and drying the adhesive sheet. Further, in this case, it is preferable to apply the adhesive composition to a release liner or the like and then dry it at 80°C to 120°C. By setting the drying temperature to 80°C or higher, a pressure-sensitive adhesive sheet can be obtained in a suitable time, and by setting the drying temperature to 120°C or lower, thermal deterioration of the support or release liner can be prevented.

<Adhesive layer>
The adhesive layer in the present invention plays a role in separating the base material by dissolving, peeling, etc. with a release liquid. Examples of the resin contained in the adhesive layer include acrylic copolymers, urethane copolymers, polyester copolymers, polyamide copolymers, etc., but acrylic copolymers may also be included. preferable.

Further, it is preferable that the adhesive layer in the present invention has an adhesive force of 3 N/25 mm or more in a 180° peel test for use in food packaging packages that do not require re-peeling.
The 180° peel test method is as follows. A sheet containing an adhesive layer and a support is prepared with a size of 25 mm in width and 100 mm in length, and the releasable sheet is peeled off from the adhesive sheet at 23° C. and in an atmosphere of 50% relative humidity, and the exposed adhesive layer is used as a base material. , and press it back and forth once with a 2kg roll. After leaving it for 24 hours, it was peeled off in a 180 degree direction at a speed of 300 mm/min using a tensile testing machine.

Further, the adhesive layer in the present invention preferably has a gel fraction of 50 to 100%, more preferably 70 to 100%, when immersed in an aqueous sodium hydroxide solution. In the present invention, "detachment" refers to cases where the adhesive layer dissolves and the base material detaches, and cases where the adhesive layer does not dissolve but peels off due to neutralization, swelling, etc. and the base material detaches. In this case, both forms are included, but by making the latter state in which the majority of peeling occurs due to swelling, the surface area of the detached adhesive layer can be kept small and the re-adhesion prevention effect of the surfactant can be enhanced. .

The method for measuring the gel fraction when immersed in an aqueous sodium hydroxide solution is as follows. The adhesive composition is applied to a polyethylene terephthalate (PET) film to a dry film thickness of about 100 μm, and then dried at 23° C. for 7 days. Next, the weight of the 200 mesh wire mesh is measured (the weight is defined as M). The pressure-sensitive adhesive sheet prepared above was cut into a size of 5 cm x 5 cm, and the weight of the test piece bonded to a 200-mesh wire mesh was measured (the weight was defined as A). Note that 200 mesh is a mesh specified by JIS G-3555. The test piece is immersed in 50 ml of an aqueous sodium hydroxide solution prepared by adding 2 parts by mass of sodium hydroxide to 98 parts by mass of ion-exchanged water, and left at 60° C. for one day. Thereafter, it is taken out, washed with ion-exchanged water, dried at 100° C. for 20 minutes, and weighed (the weight is designated as T).
Subsequently, the polyethylene terephthalate (PET) film is taken out from the test piece, the adhesive layer is removed using ethyl acetate, and the weight of the PET film is measured (the weight is defined as K). The gel fraction is determined by substituting the obtained value into the following formula (1).
Formula (1)
(T-M-K) x 100/(A-M-K)

(Acrylic copolymer)
The acrylic copolymer is a copolymer obtained by polymerizing a monomer mixture of (meth)acrylate. 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. From the viewpoint of removability, it is preferable to include (meth)acrylate having a carboxyl group.

Further, the acid value of the acrylic copolymer is preferably 0.1 to 150 mgKOH/g. When the acid value of the acrylic copolymer is 0.1 to 150 mgKOH/g, it becomes easier to achieve both adhesive properties and release properties.

[(meth)acrylate having carboxyl group]
The (meth)acrylate (a5) having a carboxyl group is, for example, (meth)acrylic acid, β-carboxyethyl acrylate, ω-carboxypolycaprolactone monoacrylate, 2-acryloyloxyethylsuccinic acid, 2-acryloyloxyethylhexahydrophthal Examples include acids. (Meth)acrylic acid is preferably used from the viewpoint 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 Examples include acrylate, dodecyl (meth)acrylate, and the like.

[(Meth)acrylate having ethylene glycol chain or propylene glycol chain]
Examples of (meth)acrylates having an ethylene glycol chain or propylene glycol chain include methoxy (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate. ) acrylate, ethoxypolypropylene glycol (meth)acrylate, and the like.

[(meth)acrylate having hydroxyl group]
Examples of (meth)acrylates having a hydroxyl group include 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, Examples include glycol mono(meth)acrylates such as polypropylene glycol mono(meth)acrylate and 1,4-cyclohexanedimethanol mono(meth)acrylate.

[Other monomers]
Monomers other than those mentioned above can also be used as long as they are copolymerizable with other (meth)acrylates. 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-epoxycyclohexylmethylmethacrylate, 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- -ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexy itaconimide, N-lauryl itaconimide, N-(meth)acryloyloxymethylene succinimide, N-( Imide group-containing monomers such as meth)acryloyl-6-oxyhexamethylene succinimide and N-(meth)acryloyl-8-oxyoctamethylene succinimide; other vinyl monomers such as vinyl acetate, styrene, methylstyrene, vinyltoluene, acrylonitrile, etc. can be mentioned.

(Manufacture of acrylic copolymer)
The acrylic copolymer is a copolymer obtained by polymerizing a monomer mixture of (meth)acrylate. Examples of the polymerization method include common polymerization methods such as solution polymerization and emulsion polymerization.

[Manufacture by emulsion polymerization]
The acrylic copolymer can be obtained, for example, by emulsion polymerization.
First, 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 part or all of water and a surfactant and stirring to form an emulsion.

After preparing these mixed solutions or emulsions, polymerization is carried out in the presence of a polymerization initiator. As a method, polymerization may be started by charging the entire mixed solution or emulsified solution into a reaction vessel, or a part of the mixed solutions or emulsions may be charged into a reaction vessel. After charging the reaction vessel and starting polymerization, it may be further divided into several portions and added, a portion may be charged into the reaction vessel and polymerization may be started, and then the remainder may be continuously added dropwise, or water and the necessary components may be added in advance. Depending on the situation, a part or all of the surfactant may be charged into a reaction vessel, and the entire amount may be continuously added dropwise. When polymerizing using a mixed solution, it is preferable to charge the entire amount of the surfactant and part or all of the water into the reaction vessel in advance.

The polymerization initiator can be added in advance by charging the entire amount into the reaction container, by adding the entire amount after raising the temperature, or by charging a portion into the reaction container and adding it several times after starting polymerization. It may be added in portions, a portion may be charged into a reaction vessel and after polymerization has started, the remainder may be continuously added dropwise, or the entire amount may be continuously added dropwise. When adding the polymerization initiator in portions or continuously dropping it, it may be added in portions or continuously dropping into the reaction vessel alone, or it may be added in portions or continuously dropping in a state mixed with a mixed solution or emulsion. good. Note that after adding the polymerization initiator by these methods, the polymerization initiator may be additionally added once or twice or more for the purpose of increasing the reaction rate. In this way, the copolymer (A) of the present invention can be obtained.

The surfactant used in emulsion polymerization is preferably selected appropriately 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 not having a radically polymerizable functional group, and both may be used. They can also be used together.

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

Examples of non-reactive anionic surfactants include polyoxyethylene polycyclic phenyl ether sulfates, higher fatty acid salts such as sodium stearate, alkylaryl sulfonates such as sodium dodecylbenzenesulfonate, and alkyl surfactants such as sodium lauryl sulfate. Examples include sulfate ester salts, polyoxyethylene alkyl ether sulfate ester salts such as polyoxyethylene lauryl ether sodium sulfate, and polyoxyethylene alkylaryl ether sulfate ester salts such as polyoxyethylene nonylphenyl ether sodium sulfate.

Examples of non-reactive nonionic surfactants include polyoxyethylene alkylphenyl ethers such as polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether; polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene. Examples include polyoxyethylene alkyl ethers such as oleyl ether; polyoxypolycyclic phenyl ethers such as polyoxyethylene distyrenated phenyl ether; and polyoxyethylene sorbitan fatty acid ester. A single surfactant or two or more kinds of surfactants can be used.

Among the above-mentioned surfactants, it is preferable to use reactive or non-reactive anionic surfactants because good polymerization stability can be obtained. The surfactant is preferably used in an amount of 0.5 to 3 parts by weight per 100 parts by weight of the monomer mixture.

A polymerization initiator is used in 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 before use. It is preferred to use agents.

Examples of water-soluble polymerization initiators include 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-methylbutanamidoxime) 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 weight, more preferably 0.02 to 0.5 parts by weight, based on 100 parts by weight of the monomer mixture. When the amount is 0.01 to 1.0 parts by mass, polymerization reactivity can be further improved.

Further, as the water-soluble polymerization initiator, a redox polymerization initiator (using an oxidizing agent and a reducing agent in combination) can be used. 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 the reducing agent include sodium sulfite, acidic sodium sulfite, Rongalite, and ascorbic acid.

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, per 100 parts by mass of the oxidizing agent and reducing agent, respectively, based on 100 parts by mass of the monomer mixture. preferable. When the amount is 0.01 to 1.0 parts by mass, the polymerization reactivity can be improved.

During emulsion polymerization, a buffer can be used to adjust the pH as necessary. The buffering agent is not particularly limited as long as it has a pH buffering effect on 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, etc. can be 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, per 100 parts by mass of the monomer mixture.

During emulsion polymerization, a chain transfer agent can be used as necessary to adjust the molecular weight. For example, compounds having 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 mercaptopropion. Examples include 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. Chain transfer agents can be used alone or in combination of two or more.
The chain transfer agent is preferably 0.01 to 7.5 parts by weight, more preferably 0.03 to 3.0 parts by weight, based on 100 parts by weight of the monomer mixture.

Furthermore, known additives such as a neutralizing agent, a leveling agent, a preservative, an antifoaming agent, a thickener, and a pigment dispersion can be added as optional ingredients.

The neutralizing agent is preferably blended in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the acrylic copolymer in order to adjust the pH 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 can be improved.

The leveling agent is preferably blended in an amount of 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, leveling properties during coating can be improved and repellency and shrinkage can be suppressed. By blending it in an amount of 1 part by mass or less, it is possible to suppress a decrease in adhesive strength and removability when forming an adhesive layer.

The preservative is preferably added in an amount of 0.1 to 1 part by weight per 100 parts by weight of the acrylic copolymer. By blending 0.1 part by mass or more, it is possible to suppress spoilage and bacterial growth of the aqueous adhesive. By blending it in an amount of 1 part by mass or less, it is possible to suppress a decrease in adhesive strength and removability when forming an adhesive layer.

The antifoaming agent is preferably blended in an amount of 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, it is possible to suppress foaming during application of the aqueous adhesive and suppress repellency due to foaming. By blending it in an amount of 1 part by mass or less, it is possible to suppress a decrease in adhesive strength and removability when forming an adhesive layer.

The amount of thickener to be blended is preferably 0.1 to 5 parts by weight per 100 parts by weight of the acrylic copolymer. By blending 0.1 part by mass or more, the water-based adhesive can be thickened and shrinkage and repellency during coating can be suppressed. By blending in an amount of 5 parts by mass or less, it is possible to suppress a decrease in adhesive force and removability when forming an adhesive layer.

Pigment dispersions are used when the adhesive layer requires hiding properties and coloring properties. The pigment dispersion is preferably blended in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the acrylic copolymer. By blending 0.1 part by mass or more, the hiding property and coloring property of the adhesive layer can be improved. By blending in an amount of 5 parts by mass or less, it is possible to suppress a decrease in adhesive force and removability when forming an adhesive layer.

[Production by solution polymerization]
The acrylic copolymer can also be obtained by adding a polymerization initiator to a monomer mixture and performing solution polymerization. Examples of the solvent used in the solution polymerization include 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.

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, polymerization can be carried out at a temperature of about 50° C. to 90° C. for 6 hours to 20 hours under a nitrogen stream. Furthermore, during polymerization, the molecular weight of the copolymer can be appropriately adjusted using a chain transfer agent.

Chain transfer agents used in solution polymerization include, for example, n-dodecyl mercaptan, mercaptoisobutyl alcohol, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, and glycidyl mercaptan. , α-methylstyrene dimer, carbon tetrachloride, chloroform, and hydroquinone. The chain transfer agent can be used in an amount of about 0.01 to 1 part by weight per 100 parts by weight of the monomer mixture.

Polymerization initiators used in solution polymerization are generally azo compounds and organic peroxides.
Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane 1-carbonitrile), 2,2'-azobis(2-methylbutyronitrile), '-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) ) etc.

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

(hardening agent)
The adhesive layer in the present invention can further contain a curing agent. Examples of the curing agent include titanium chelate compounds, aluminum chelate compounds, zirconium chelate compounds, zinc oxide, aziridine compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, and hydrazide compounds. The 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 weight, more preferably 0.03 to 8 parts by weight, per 100 parts by weight of the acrylic copolymer. By blending 0.01 to 10 parts by mass, the adhesion to the base material and cohesive force are further improved.

(tackifying resin)
The adhesive layer in the present invention may further contain a tackifier resin. Examples of the tackifying resin include a rosin-based tackifying resin, a synthetic hydrocarbon-based tackifying resin, a terpene-based tackifying resin, a terpene-phenol-based tackifying resin, or an emulsion type using these. By including these tackifying resins, the adhesive force can be further improved.

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

Examples of the synthetic hydrocarbon-based tackifying resin include coumaron-based resins, coumaron-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 0 to 160°C, more preferably 0 to 120°C, even more preferably 0 to 100°C. When the softening point of the tackifier resin is 0 to 160°C, it becomes easy to achieve both adhesive properties and release properties. Note that the softening point is a softening temperature measured according to the dry bulb method specified in JIS K5902.

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

EXAMPLES The present invention will be explained in more detail below using examples, but the present invention is not limited to the examples. In the examples, "parts" means "parts by mass" and "%" means "% by mass."
Further, the blending amounts in the table are parts by mass, and values other than water and solvent are nonvolatile content equivalent values. In addition, a blank column in the table indicates that it is not blended.

Note that the acid value of the acrylic copolymer was measured by the following method.
<Measurement of acid value>
Precisely 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) mixture, dissolve it, and add 0.1N-alcohol. Titration was carried out using potassium hydroxide solution. The acid value (unit: mgKOH/g) was determined by the following formula. In addition, the acid value was taken as the value of the dried sample.
Acid value = {(5.61×a×F)/S}/(nonvolatile content concentration/100)
S: Amount of sample collected (g)
a: Consumption amount (ml) of 0.1N-alcoholic potassium hydroxide solution
F: Factor of 0.1N-alcoholic potassium hydroxide solution

<Production of acrylic copolymer>
[Production Example 1-1] (Production of copolymer (A-1))
2.5 parts of tert-dodecyl mercaptan as a chain transfer agent was dissolved in 88 parts of n-butyl acrylate and 12 parts of methacrylic acid. Further, 6.7 parts of Nucor 707SF (aqueous solution of polyoxyethylene polycyclic phenyl ether sulfate salt, 30% active ingredient, manufactured by Nippon Nyukazai Co., Ltd.) as an anionic surfactant, and 5.5 parts of a 5% ammonium persulfate aqueous solution as an initiator. 6 parts were dissolved in 35 parts of ion-exchanged water, and the mixture was added and stirred to obtain an emulsion. This was placed in a dropping funnel.
Put 72.5 parts of deionized water into a four-necked flask equipped with a stirrer, cooling tube, thermometer, and above-mentioned dropping funnel, replace the air inside the flask with nitrogen gas, and raise the internal temperature to 80°C while stirring. 2.4 parts of 5% ammonium persulfate aqueous solution was added. After 5 minutes, the emulsion was added dropwise from the dropping funnel over a period of 3 hours.
While maintaining the internal temperature at 80°C, the mixture was further aged at 80°C for 4 hours with stirring, and then cooled to obtain a copolymer (A-1).

[Production Examples 1-2 to 8] (Production of copolymers (A-2 to 8))
Copolymers (A-2 to A-8) were obtained in the same manner as [Production Example 1-1] except that the types and amounts of monomers, surfactants, and initiators were changed as shown in Table 1.

[Production Example 1-9] (Production of copolymer (A-9))
In a four-necked flask equipped with a stirrer, condenser, thermometer, and above-mentioned dropping funnel, 94.9 parts of n-butyl acrylate, 0.1 part of 2-hydroxyethyl acrylate, 5 parts of acrylic acid, and acetic acid were added 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 the start of the polymerization reaction was confirmed, and the reaction was continued at reflux temperature for 2 hours. Next, 0.005 part of 2,2'-azobisisobutyronitrile was added to the reaction solution, and the reaction was continued for 6 hours. Thereafter, the reaction vessel was cooled and 130 parts of ethyl acetate was added to obtain a copolymer (A-9) solution.

[Production Examples 1-10 to 17] (Production of copolymers (A-10 to 17))
Copolymers (A-10 to A-17) were obtained in the same manner as [Production Example 1-9] except that the types and amounts of monomers and initiators were changed as shown in Table 2.

The abbreviations in Tables 1 and 2 are listed below.
2EHA: 2-Ethylhexyl acrylate BA: n-butyl acrylate MA: Methyl acrylate MMA: Methyl methacrylate MEA: Methoxyethyl acrylate AM-90G: Manufactured by Shin-Nakamura Chemical Co., Ltd., NK Ester AM-90G (methoxypolyethylene glycol acrylate)
HEA: 2-hydroxyethyl acrylate MAA: methacrylic acid AA: acrylic acid S-710: Sila Ace S-710 (3-(trimethoxysilyl)propyl methacrylate) manufactured by JNC Corporation
707SF; manufactured by Nippon Nyukazai Co., Ltd., Newcor 707SF (aqueous solution of polyoxyethylene polycyclic phenyl ether sulfate salt, active ingredient 30%)
KH-10: Daiichi Kogyo Seiyaku Co., Ltd., Aqualon KH-10 ((polyoxyethylene-1-(allyloxymethyl)alkyl ether sulfate ammonium salt)
APS: ammonium persulfate AIBN: 2,2'-azobisisobutyronitrile

<Manufacture of adhesive sheet>
[Production Example 2-1] (Production of adhesive sheet (B-1))
After mixing 30 parts of copolymer (A-1) and 70 parts of copolymer (B-1), 0.3 part of Adekanate B-940 (manufactured by ADEKA) was added as an antifoaming agent, and Perex was added as a leveling agent. Add 0.2 parts of OT-P (manufactured by Kao Corporation) and 0.05 parts of Revanax FX-360 (manufactured by Shoei Chemical Co., Ltd.) as a preservative, and further adjust the pH with an alkaline thickener and aqueous ammonia (Horiba, Ltd. pH meter D). -52) and viscosity adjustment to obtain an adhesive composition with pH 8.0 and viscosity 2,000 mPa (BL type viscometer #4-12 rpm).
The resulting adhesive composition was applied onto a releasable sheet using a comma coater so that the coating amount after drying was 15 g/m ² , and dried in a drying oven at 100° C. for 120 seconds. A pressure-sensitive adhesive sheet (B-1) was obtained by laminating thermal paper (manufactured by Ricoh Co., Ltd., 150LA-1) as a support material.

[Production Examples 2-2 to 11] (Production of adhesive sheets (B-2 to 11))
Adhesive sheets (B-2 to B-11) were obtained in the same manner as [Manufacturing Example 2-1] except that the composition and blending amount were changed as shown in Table 3.

[Production Example 2-12] (Production of adhesive (B-12))
To 100 parts of copolymer (A-9), 0.5 part of aluminum chelate A (manufactured by Kawaken Fine Chemical Co., Ltd., aluminum trisacetylacetonate) was blended as a curing agent, and ethyl acetate was added as a solvent to reduce the nonvolatile content. The adhesive composition was adjusted to 30%.
The resulting adhesive composition was applied onto a releasable sheet using a comma coater so that the coating amount after drying was 15 g/m ² , and dried in a drying oven at 100° C. for 120 seconds. The adhesive sheet 12 (B-12) was obtained by bonding with thermal paper (manufactured by Ricoh, 150LA-1) as a support material and aging for one week at a temperature of 23° C. and a relative humidity of 50%.

[Production Examples 2-13 to 27] (Adhesive sheet (manufacture of B-13 to B-27)
Adhesive sheets (B-13 to B-27) were obtained in the same manner as [Manufacturing Example 2-12] except that the composition and blending amount were changed as described in Tables 4-1 and 4-2 (Table 4 below). .

The abbreviations in Tables 3 and 4 are listed below.
SN-385NS: Manufactured by Harima Kasei Co., Ltd., Hariestar SN-385NS (rosin emulsion, base resin softening point 85°C)
A-75: Superester A-75 (rosin ester, softening point 70-80°C), manufactured by Arakawa Chemical Industry Co., Ltd.
Aluminum chelate A: Manufactured by Kawaken Fine Chemical Co., Ltd., aluminum chelate A (aluminum trisacetylacetonate)
TETRAD-X: manufactured by Mitsubishi Gas Chemical Co., Ltd., TETRAD-X (N, N, N', N'-tetraglycidyl-m-xylylenediamine)
TDI/TMP: trimethylolpropane adduct of tolylene diisocyanate (nonvolatile content 37.5%)

The supports in Tables 3 and 4 are described below.
Thermal paper: manufactured by Ricoh, 150LA-1 (paper thickness 82±9μm)
Coated paper: Manufactured by Oji Paper Co., Ltd., Mirror Coat Gold (cast coated paper containing calcium carbonate, basis weight 84.9 g/m ² )
PET: Polyethylene terephthalate film, thickness 50μm
PP: Polypropylene film, thickness 40μm

<Production of desorption liquid>
[Production Example 3-1] (Production of desorption liquid (C-1))
1 part of POE alkyl ether A (polyoxyethylene lauryl ether, POE addition number: 4, HLB: 9.7) as a surfactant, BYK-1650 (manufactured by BYK Chemie Japan, silicone emulsion type antifoaming agent) as an antifoaming agent. , solid content concentration 27.5%), 2 parts of sodium hydroxide, and 96.9 parts of water were mixed and stirred with a disper to obtain a desorbed liquid (C-1).

[Production Examples 3-2 to 28] ((Production of desorption liquid (C-2 to 23, C'-1 to 5))
A desorption solution (C-2 to 23, C'-1 to 5) was obtained in the same manner as in [Production Example 3-1] except that the composition and blending amount were changed as shown in Tables 5 and 6.

The abbreviations and materials in Tables 5 and 6 are described below.
[Surfactant]
(Nonionic surfactant)
POE alkyl ether A: polyoxyethylene (POE) lauryl ether, POE addition number: 4, HLB: 9.7
POE alkyl ether B: POE lauryl ether, POE addition number: 12, HLB: 15.3
POE alkyl ether C: POE stearyl ether, POE addition number: 12, HLB: 13.9
POE alkyl ether D: POE oleyl ether, POE addition number; 13, HLB; 13.6
POE acetylene diol A: POE addition number; 1.3, HLB; 4.0
POE acetylene diol B: POE addition number; 30, HLB; 17
(Anionic surfactant)
Sodium lauryl sulfate: HLB; >20
POE alkyl ether phosphoric acid A: POE alkyl ether phosphoric acid, number of alkyl carbons: 12 to 15, number of POE additions: 4, HLB: 13.3
POE alkyl ether phosphate B: POE lauryl ether phosphate, POE addition number: 4, HLB: 10.0
(Cationic surfactant)
Stearyltrimethylammonium chloride: HLB; 8.9
[Defoaming agent]
BYK-018: Manufactured by BYK Chemie Japan, silicone oil compound type, solid content >97%
BYK-1770: Manufactured by BYK Chemie Japan, silicone oil type, solid content >96%
TEGO Foamex 1448: manufactured by Evonik Japan, silicone emulsion type, solid content 24%, main agent: water KM-89: manufactured by Shin-Etsu Chemical, silicone emulsion type, solid content 34%, main solvent: water KS -540: Manufactured by Shin-Etsu Chemical, silicone self-emulsifying type, solid content concentration 100%,
BYK-015: Manufactured by BYK-Chemie Japan, solid content concentration >97%
BYK-1640: Manufactured by BYK Chemie Japan, non-silicone type, solid content concentration 62%, main solvent: water

<Manufacture of laminate>
(Manufacture of laminate (D-1))
At 23°C and in an atmosphere of 50% relative humidity, peel off the release sheet from the adhesive sheet (B-2) and attach the exposed adhesive layer to the base material (polyethylene terephthalate film, thickness 200 μm), and press it back and forth with a 2 kg roll once. In this way, a laminate (D-1) was obtained.

(Manufacture of laminates (D-2 to 29))
Laminates (D-2 to 29) were obtained in the same manner as laminate (D-1) except that the adhesive sheet and base material were changed to those listed in Tables 7-1 to 7 (Table 7 below). .

The base materials in Tables 7-1 to 7-7 are described below.
PET: Polyethylene terephthalate film, thickness 200μm
PS: Polystyrene film, thickness 100μm
PP: Polypropylene film, thickness 100μm
Non-woven fabric: Asahi DuPont Flash Spun Products, Tyvek 1073D hard type (polyethylene non-woven fabric)

<Separation and recovery of base material>
[Example 1]
In a 1000 mL stainless steel beaker, put 400 g of the desorption liquid (C-4) and 12 g of a test piece cut into a size of 1 cm x 1 cm from the laminate (D-1) produced above, and heat the mixture at 80°C and 2000 rpm. It was stirred with
The desorbed liquid was filtered using a 10-mesh stainless steel mesh, and the PET base material remaining on the mesh was washed with water and dried to separate and recover the base material.

[Examples 2-6, 8-23, 25-52, Comparative Examples 1-5]
The base material was separated and recovered in the same steps as in Example 1, except that the laminate and the desorption liquid were changed to those listed in Table 7.

[Example 7]
In a 1000 mL stainless steel beaker, put 400 g of the desorption liquid (C-4) and 12 g of a test piece cut out from the manufactured laminate (D-7) into a size of 1 cm x 1 cm, and stir at 80 ° C. and 2000 rpm. did.
The base material after desorption floating near the surface of the desorption liquid was scooped out, washed with water, and dried to separate and recover the base material.

[Example 24]
Separation and recovery was carried out in the same steps as in Example 7, except that the laminate and the desorbed liquid were changed to those listed in Table 7.

In each example, the following evaluations were performed in the step of immersing the laminate in a release liquid to remove the adhesive layer. The results are shown in Table 7.

<Evaluation method>
(defoaming)
Ten minutes after the start of stirring, the stirring was temporarily interrupted, and the height of the liquid level (above the bubbles) was visually observed and evaluated based on the following criteria. The height refers to the capacity scale written on the beaker, and the larger the number, the higher the liquid level, that is, the more bubbles are generated.
A (Excellent): The height of the liquid level (above the bubbles) during stirring is less than 500 mL B (Good): The height of the liquid level (above the bubbles) during stirring is 500 mL or more and less than 700 mL C (Acceptable): During stirring The height of the liquid level (above the bubbles) is 700 mL or more and less than 900 mL D (not allowed): The height of the liquid level (above the bubbles) during stirring is 900 mL or more

(removability)
At 15 minutes, 30 minutes, and 1 hour after the start of stirring, the test pieces were collected, washed with water, and dried. Supports and substrates were selected one by one using FT-IR and visual inspection, and 10 substrates were sampled. The presence or absence of an absorption peak of the adhesive was confirmed using FT-IR at 30 locations, 3 locations on the front and back sides of each base material, and evaluated based on the following criteria.
A (excellent): In the base material collected 15 minutes after the start of stirring, absorption peaks of the adhesive layer were observed at less than 5 locations.
B (Good): In the base material collected 30 minutes after the start of stirring, for the first time, the number of locations where absorption peaks of the adhesive layer were confirmed is less than 5.
C (Acceptable): In the base material collected 1 hour after the start of stirring, for the first time, the number of locations where the absorption peak of the adhesive layer was confirmed is less than 5 locations.
D (unacceptable): Absorption peaks of the adhesive layer were observed at 6 or more locations in the base material collected 1 hour after the start of stirring.

(Reattachability)
In the removability evaluation, stirring was continued for an additional 60 minutes from the time when the absorption peak of the adhesive layer was no longer observed at 25 or more of the 30 locations. Thereafter, the test pieces were collected, washed with water, and dried. Supports and substrates were selected one by one using FT-IR and visual inspection, and 10 substrates were sampled. The presence or absence of an absorption peak of the adhesive was confirmed using FT-IR at a total of 30 locations, 3 locations on the front and back sides of each base material.
In the removability evaluation, for the comparative example with an evaluation result of D, it was judged that the reattachment evaluation was difficult and was not conducted.
A (Excellent): Absorption peaks of the adhesive layer were observed at less than 5 locations.
B (Good): Absorption peaks of the adhesive layer were observed at 5 or more and less than 8 locations.
C (Acceptable): Absorption peaks of the adhesive layer were observed at 8 or more and less than 10 locations.
D (unacceptable): Absorption peaks of the adhesive layer were confirmed at 10 or more locations.

The above evaluation results indicate that the desorption liquid of the present invention can easily detach the adhesive sheet from the laminate and recover a high-quality base material with less re-adhesion of the adhesive layer. .

Claims (4)

A method for separating and recovering a base material from a laminate in which a base material is laminated with a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer and a support having a coating amount of 10 to 100 g/ ^m2 , the method comprising:
including the step of immersing the laminate in a release liquid to release the adhesive sheet,
The desorbing liquid contains a basic compound, a surfactant with an HLB value of 7 or more, and an antifoaming agent,
Separation and recovery method of base material. 2. The method for separating and recovering a base material according to claim 1, wherein the antifoaming agent is at least one selected from the group consisting of emulsion-type silicone compounds, self-emulsifying silicone compounds, and non-silicone compounds. The method for separating and recovering a base material according to claim 1, wherein the surfactant includes at least one of a nonionic surfactant and an anionic surfactant. The adhesive layer is an adhesive layer containing an acrylic copolymer, the acrylic copolymer is a copolymer of a monomer mixture containing (meth)acrylate having a carboxyl group, and the acrylic copolymer is a copolymer of a monomer mixture containing (meth)acrylate having a carboxyl group. The method for separating and recovering a base material according to any one of claims 1 to 3, wherein the acid value of the polymer is 0.1 to 150 mgKOH/g.