JPH08333550A - Tacky sheet - Google Patents

Abstract

PURPOSE: To obtain a tacky sheet capable of readily disintegrating without adversely being affected by a tacky agent and a film and doing not care even if mixed into a recyle process by using the film as the surface substrate. CONSTITUTION: In this tacky sheet, a surface substrate comprises a film having defibrability to an aqueous solution of an alkali and composed of a lactic acid- based polymer and a tacky agent constituting a tacky agent layer is a copolymer obtained by neutralizing a carboxylic acid-modified rosin-containing acrylic acid ester copolymer composed of a composition composed of (a) 5-40wt.% (poly)ethylene glycol (meth)acrylate monomer, (b) 5-40wt.% carboxylic acid- modified rosin ester monomer, (c) 30-60wt.% (meth)acrylic acid 4-18C alkylester monomer, (d) 5-20wt.% ethylenic unsaturated carboxylic acid-containing monomer and (e) 5-20wt.% monomer copolymerizable with these components (a), (b), (c) and (d) with an alkaline substance and having re-defibrability to water or an alkali aqueous solution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive sheet using a film as a surface base material, and more particularly, to easily disintegrate the pulp and the film without adversely affecting the pressure-sensitive adhesive and the film. The present invention relates to a pressure-sensitive adhesive sheet that can be mixed in the recycling process.

[0002]

2. Description of the Related Art Adhesive sheets have been processed into labels, stickers, stickers, patches, etc. in a very wide range for commercial use, office use, household use and the like. The general structure of the pressure-sensitive adhesive sheet is one in which a pressure-sensitive adhesive layer is formed between a surface base material and a release sheet, and paper, film, metal foil or the like is used for the surface base material, and the release sheet is glassine. High density base paper such as paper, clay coated paper, polyethylene laminated base paper, etc. coated with a release agent such as a silicone compound or a fluorine compound is used. As the pressure-sensitive adhesive, various types of rubber-based, acrylic-based, vinyl ether-based emulsion, solvent or solventless pressure-sensitive adhesives are used. Such an adhesive sheet is a permanent adhesive type that is permanently used while being attached to an adherend after being attached to a product, etc. It is a removable type.

On the other hand, regarding the recycling of used paper, in Japan, the amount of used waste paper, including recycled waste paper, exceeds 50% of the raw materials for paper and paperboard production, as a raw material for pulp production, and it is already the main raw material. Has occupied the position of. Recycled pulp can be used in newspapers, cardboards, magazines, imitations, colors (including art), whites, cards, special whites, middle whites, white manila, tickets, old Chinese fabrics, tea imitations Paper), mount, land ticket, ball, thermal recording paper, pressure-sensitive copying paper, OCR paper, and the like. In general, these methods for reclaiming pulp from waste paper include a disintegration step for disintegrating waste paper to obtain a pulp suspension, a rough selection for separating foreign matters in the pulp suspension, a fine selection step, and a de-settling for separating printing ink. Regenerated pulp is formed through a black ink process and a bleaching process that whitens the color.

However, wax-processed paper, polyethylene-laminated paper, adhesive sheets, etc. cannot separate water-insoluble wax, polyethylene, adhesives, etc. from pulp fibers, making it difficult to make recycled pulp. It is considered to be waste paper. Particularly, in the case of a pressure-sensitive adhesive sheet, a water-insoluble pressure-sensitive adhesive is contained in an amount of 5 to 50%, and since this pressure-sensitive adhesive has a strong adhesive force, it is impossible to separate it from pulp fibers.

With the adhesive still contained in the recycled pulp,
When the paper is made using the recycled pulp, the adhesive may block the eyes of the wire in the paper making process, stain the press roll or the blanket, cause paper breakage, and cause a problem of significantly lowering paper making efficiency. However, there is a problem in that the formation of spots on the paper surface and other adverse effects on paper layer formation or quality.

In particular, a pressure-sensitive adhesive sheet using a plastic film such as polyethylene, polyvinyl chloride, polystyrene, polyethylene terephthalate as a surface substrate is not disintegrated or hardly disaggregated and is difficult to remove, and it is difficult to remove during the re-pulping process. It has a bad influence. At present, it is the actual situation that used paper including a pressure-sensitive adhesive sheet having a film as a surface base material is separated as an industrial waste by manually separating only the pressure-sensitive adhesive sheet from recovered magazines.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and provides a surface substrate with a film which is easily disintegrated even when mixed with general waste paper and does not adversely affect recycled pulp. The adhesive sheet used is provided.

[0008]

The present invention provides a release sheet,
In a pressure-sensitive adhesive sheet formed by laminating a pressure-sensitive adhesive layer and a surface base material, the surface base material is a film composed of a lactic acid-based polymer and having a disintegration property against an alkaline aqueous solution, and the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is A carboxylic acid-modified rosin-containing acrylic acid ester copolymer having the following composition, which is a copolymer neutralized with an alkaline substance, and characterized in that it is a pressure-sensitive adhesive having re-degradability with respect to water or an aqueous alkaline solution. It is an adhesive sheet. (A) a carboxylic acid-modified rosin ester monomers .. 5 to 40 wt% (b) (poly) ethylene glycol (meth) acrylate monomers .. 5 to 40 wt% (c) (meth) C ₄ -C ₁₈ acrylic acid Alkyl ester monomer: 30 to 60% by weight (d) Ethylenically unsaturated carboxylic acid-containing monomer: 5 to 20% by weight (e) Monomer copolymerizable with the above a, b, c and d :: 5 to 20 weight%

[0009]

The present invention uses a film made of a lactic acid type polymer as a surface base material. In order to solve the problems of the present invention, polyhydroxybutyric acid or a copolymer of hydroxybutyric acid and hydroxyvaleric acid, a polymer of hydroxycarboxylic acid such as poly (3-hydroxyalkanoate), polybutylene succinate or polyethylene succinate or Films having a disaggregation property with respect to an alkaline aqueous solution, such as a condensation product of them and succinic acid, are also conceivable.However, these films are opaque and have elasticity, and wrinkles may occur during adhesion processing. Insufficient sheet quality.

Specific examples of lactic acid-based polymers include copolymers of polylactic acid, lactic acid or lactide with hydroxycarboxylic acids such as glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid and hydroxyheptanoic acid. And so on. The structural unit of polylactic acid is poly (L-lactic acid) consisting only of L-lactic acid.
Lactic acid), poly (D-lactic acid) consisting only of D-lactic acid, and poly (DL-lactic acid) in which both are connected in various proportions can be used.

Lactic acid-based polymers which are preferably used are obtained by dehydration condensation of raw material monomers, or lactide which is a cyclic dimer of lactic acid, and glycolide, caprolactone,
It can be obtained by ring-opening polymerization of cyclic esters such as propiolactone, butyrolactone and valerolactone. The weight average molecular weight of the polymer is preferably about 50,000 to 1,000,000. By the way,
If the molecular weight is less than 50,000, physical strength and heat-resistant dimensional stability tend to be poor, which is not suitable for adhesive processing. Also,
If the molecular weight exceeds 1,000,000, the film becomes too steel and is not suitable for adhesive processing.

The surface base material may be subjected to various kinds of processing which are carried out in the field of pressure-sensitive adhesive sheets. For example, a pigment coating layer may be provided to improve printability, a thermosensitive coloring layer or an ink receiving layer, etc. May be provided to provide the function as various recording materials, or a concealing layer may be provided, and further, coloring or printing may be performed.

The pressure-sensitive adhesive used in the pressure-sensitive adhesive sheet of the present invention is (a) a carboxylic acid-modified rosin ester monomer ... 5-40% by weight (b) a (poly) ethylene glycol (meth) acrylate monomer. wt% (c) (meth) C ₄ -C ₁₈ alkyl ester monomers .. 30-60% by weight (d) an ethylenically unsaturated carboxylic acid containing monomer .. 5 to 20 wt% of acrylic acid (e) above a, Monomer copolymerizable with b, c, and d ... A carboxylic acid-modified rosin-containing acrylic acid ester copolymer having a composition of 5 to 20% by weight, which is a copolymer obtained by neutralizing with an alkali.

Examples of the (a) carboxylic acid-modified rosin ester monomer include compounds represented by the following general formula 1.

[0015]

Embedded image

[Wherein R is a methyl group or a hydrogen atom, m
Represents an integer of 1 to 8. ]

The carboxylic acid-modified rosin ester monomer must be copolymerized in the range of 5 to 40% by weight. Incidentally, if it is less than 5% by weight, the water re-disaggregation becomes insufficient. On the other hand, when it exceeds 40% by weight, the cohesive force of the pressure-sensitive adhesive becomes poor and the function of the pressure-sensitive adhesive sheet deteriorates.

As the (b) (poly) ethylene glycol (meth) acrylate monomer, the following general formula 2
The compound represented by can be illustrated.

[0019]

Embedded image

[Wherein R ₁ is a methyl group or a hydrogen atom,
R ₂ represents a methyl group, a phenyl group, an acryloyl group or a methacrylyl group, and n represents an integer of 1-10. ]

The (poly) ethylene glycol (meth) acrylate monomer should be copolymerized in the range of 5 to 40% by weight. Incidentally, if it is less than 5% by weight, the disintegration property to an alkaline aqueous solution becomes insufficient. On the other hand, 4
If it exceeds 0% by weight, the cohesive force of the pressure-sensitive adhesive decreases, and the function of the pressure-sensitive adhesive sheet decreases.

Further, (c) C _{4 of} (meth) acrylic acid
Specific examples of the C ₁₈ alkyl ester monomer include butyl (meth) acrylate, hexyl (meth) acrylate,
Octyl (meth) acrylate, (meth) acrylic acid-2
-Ethylhexyl, stearyl (meth) acrylate, etc. are mentioned. Then, the proportion of this monomer in the copolymer portion is copolymerized in the range of 30 to 60% by weight.
Incidentally, if it is less than 30% by weight, the adhesive strength of the pressure-sensitive adhesive becomes poor, and if it exceeds 60% by weight, the water re-disaggregation becomes insufficient.

Specific examples of the (d) ethylenically unsaturated carboxylic acid-containing monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, monoalkyl maleic acid, monoalkyl itaconic acid, monoalkyl fumaric acid. Acid etc. are mentioned. Then, the proportion of this monomer in the copolymer portion is copolymerized in the range of 5 to 20% by weight. Incidentally, if it is less than 5% by weight, the cohesive force of the adhesive becomes poor, and if it exceeds 20% by weight, the adhesive force of the adhesive becomes insufficient.

Further, (e) above (a), (b), (c)
Specific examples of other monomers copolymerizable with and (d) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, cyclohexyl (meth) acrylate, and (meth) acrylic. Methoxyethyl acrylate, ethoxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, styrene , Divinylbenzene, ethylene, (meth) acrylonitrile, (meth) acrylamide, N-
Butoxymethyl (meth) acrylamide, N, N'- methylene bis (meth) acrylamide, etc. are mentioned. The proportion of these copolymerizable monomers in the copolymer is adjusted within the range of 5 to 20% by weight.

Among these other copolymerizable monomers (e), methyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, divinylbenzene and (meth) are particularly preferable. Acrylonitrile, (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N, N'-methylenebis (meth)
Acrylamide and the like are preferable in terms of crosslinkability, glass transition temperature, adhesion performance and the like.

Here, the role of each of the above-mentioned monomers with respect to the pressure-sensitive adhesive of the present invention will be briefly described. As components that impart water redispersibility of the pressure-sensitive adhesive, (a) a carboxylic acid-modified rosin ester monomer and (b) ( Poly) ethylene glycol (meth) acrylate monomers are both important,
Next, as a component for imparting tackiness of the adhesive, (c)
(Meth) C ₄ -C ₁₈ alkyl ester monomers of acrylic acid is important, as the component for further impart cohesive strength of the adhesive, it is important (d) an ethylenically unsaturated carboxylic acid-containing monomers.

Therefore, in order to obtain a pressure-sensitive adhesive having excellent re-degradability with respect to water and good adhesive performance as in the present invention, the above-mentioned (a) carboxylic acid-modified rosin ester monomer and (b) ( Poly) ethylene glycol (meth) acrylate monomer, (c) (meth) acrylic acid C ₄ ~
The balance of the formulation of the C ₁₈ alkyl ester monomer, (d) the ethylenically unsaturated carboxylic acid-containing monomer, and (e) the other monomer copolymerizable therewith is extremely important.

The method for producing the above copolymer is not particularly limited, and examples thereof include water, a solvent,
It is produced by a known method such as a method of solution polymerization in the presence of a chain transfer agent or a polymerization initiator, or a method of emulsion polymerization in an aqueous system in the presence of an emulsifier, a chain transfer agent, a polymerization initiator or a dispersant. .

The monomer concentration during polymerization is usually 30 to 70.
Weight%, preferably about 40 to 60% by weight is suitable. Examples of the polymerization initiator used in the polymerization include persulfates such as potassium persulfate and ammonium persulfate, 2,2′-azobisisobutyronitrile, 2,2 ′.
-Azo compounds such as azobis (2,4-dimethylvaleronitrile), hydrogen peroxide, benzoyl peroxide,
Examples thereof include so-called redox-based polymerization initiators, which are composed of peroxides such as lauryl peroxide, and combinations of ammonium persulfate with sodium sulfite, acidic sodium sulfite, and the like. The amount of the polymerization initiator used is usually 0.2 to 2 parts by weight, more preferably, the total amount of the monomers used for the polymerization.
It is adjusted in the range of 0.3 to 1 part by weight.

Further, as a chain transfer agent to be added upon copolymerization, alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, dodecyl mercaptan, octyl thioglycolate, nonyl thioglycolate, and 2-ethylhexyl thioglycolate. , Thioglycolic acid esters such as β-mercaptopropionate-2-ethylhexyl, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-
Isopropylidene-1-cyclohexene and the like can be mentioned. Particularly, thioglycolic acid esters, 2,4
When -diphenyl-4-methyl-1-pentene or 1-methyl-4-isopropylidene-1-cyclohexene is used, the copolymer obtained has a low odor, which is preferable. The amount of the chain transfer agent used is adjusted in the range of about 0.001 to 3 parts by weight of all the monomers to be polymerized.

The polymerization reaction is usually carried out at a temperature of 60 to 100 ° C. for 2 to 8 hours. Furthermore, a wetting agent, a leveling agent, a thickening agent, an antifoaming agent, an antiseptic agent and the like can be added appropriately.

The copolymer obtained by the above-mentioned method has a carboxyl group in the copolymer, such as sodium hydroxide, potassium hydroxide, ammonia, various primary and secondary groups.
It is imparted with water solubility by neutralizing with an appropriate alkaline substance such as high-grade or tertiary amine, and thus the water redispersibility of the resulting copolymer film appears.

The glass transition temperature of the above copolymer is -6.
It is in the range of 0 to -30 ° C and is appropriately selected according to the purpose. Incidentally, the glass transition temperature of the copolymer is -60.
If the temperature is lower than ℃, the cohesive force of the obtained coating becomes insufficient, and if it exceeds -30 ℃, the coating of the obtained copolymer tends to be too hard, resulting in poor practicality.

The present invention uses such a copolymer as a pressure-sensitive adhesive and employs a specific film as the surface substrate, so that the film can be used as the surface substrate which may be mixed in the recycling process of used paper. The obtained pressure-sensitive adhesive sheet is obtained.

The base material of the release sheet used in the present invention is high-density base paper such as glassine paper, clay-coated paper, kraft paper, or high-quality paper such as casein,
Dextrin, starch, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, acrylic acid Such as ester copolymers,
A release base material such as a sheet provided with a sealing layer containing a natural or synthetic resin and a pigment as a main component, a kraft paper or a high-quality paper laminated with polyethylene or the like, a film such as polypropylene, or the like can be used. In addition, lactic acid such as polylactic acid, lactic acid or a copolymer of lactic acid or lactide with hydroxycarboxylic acid such as glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid or hydroxyheptanoic acid can be used for kraft paper or high-quality paper. You may use what laminated | stacked the type | system | group polymer and these lactic acid type polymer films themselves. Then, a water-dispersed, solvent-based or solvent-free silicone resin, fluororesin or the like is applied to these release substrates at a dry weight of 0.0
After being coated at about 5 to 3 g / m ² , a release layer is formed by heat curing, ionizing radiation curing or the like.

In particular, in the constitution of the pressure-sensitive adhesive sheet including the release sheet, considering that it is mixed in the recycling process, clay-coated paper, kraft paper, high-quality paper or the like among the above-mentioned release substrates can be used as natural or synthetic. Water-soluble release material with a sealing layer containing resin and pigment as main components in a dry weight of about 0.1 to 10 g / m ² or water-soluble polymer such as polyvinyl alcohol, carboxymethyl cellulose, and methyl cellulose Hydrolyzed with a film or an alkaline aqueous solution formed from a copolymer of polylactic acid, lactic acid or lactide and a hydroxycarboxylic acid such as glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, or hydroxyheptanoic acid. Lactic acid-based polymer film, kraft paper or high-quality paper Release substrate consisting of those laminated with Rimmer is desirable.

There is no particular limitation on the method of forming the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer is formed by coating the pressure-sensitive adhesive on the surface of the release agent layer of the release sheet according to a conventional method and drying, and the surface substrate is attached. It is finished together. in this case,
The pressure-sensitive adhesive is usually adjusted to a viscosity of about 10 to 8,000 centipoise by a means such as molecular weight adjustment, dilution with water, or thickening, and is applied to the release sheet. , For example, reverse roll coater,
Knife coater, air knife coater, bar coater, slot die coater, lip coater, reverse gravure coater, etc. are used, and the coating amount of the adhesive is 5
It is adjusted in the range of about 50 g / m ² . By the way, 5g
If it is less than / m ² , the adhesive performance of the resulting pressure-sensitive adhesive sheet will be insufficient, while if it exceeds 50 g / m ² , the pressure-sensitive adhesive may stick out during bonding of the pressure-sensitive adhesive sheets or cause cohesive failure during peeling. is there.

[0038]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these. Unless otherwise specified, all parts, proportions, coating amounts and the like in the examples are shown by solid weight.

Example 1 (Synthesis of carboxylic acid-modified rosin ester) 70 g of methacrylic acid and 90 g of epichlorohydrin were placed in a flask equipped with a stirrer, an exhaust pipe, a dropping funnel, a nitrogen suction pipe, and a thermometer.
Was charged, the temperature was raised to 100 ° C. under nitrogen gas, and the temperature was maintained for 2 hours. Then, the fully dissolved rosin abietic acid was added to 3
00 g was added and the mixture was kept at 230 ° C. for 2 hours. Next, 125 g of glutaric anhydride was added, and the mixture was kept at 230 ° C. for 2 hours to synthesize a carboxylic acid-modified rosin ester represented by the following [Chemical Formula 3].

[0040]

Embedded image

(Production of pressure-sensitive adhesive) First, a carboxylic acid-modified rosin ester represented by [Chemical Formula 3]: 6 was prepared as an emulsified monomer mixed liquid.
0 parts Methoxydiethylene glycol methacrylate: 60 parts Butyl acrylate: 100 parts 2-Ethylhexyl acrylate: 100 parts Acrylic acid: 40 parts Dimethylaminoethyl methacrylate: 40 parts Anionic emulsifier (trade name: Emal NC-35, Kao) (Manufactured by the company): 6 parts Ion-exchanged water: 150 parts were mixed to prepare.

Next, a flask equipped with a stirrer, a cooler, a dropping funnel, a nitrogen suction tube, and a thermometer was charged with 150 parts of ion-exchanged water, 3 parts of potassium peroxide, and 3 parts of octyl mercaptan, and the mixture was replaced with nitrogen at 80 ° C. After heating to
The emulsified monomer mixture liquid was dropped ⅙. Reaction rate is 9
When it reached 0%, the remaining monomer mixture was added dropwise over 3 hours to carry out polymerization. After the dropping was completed, the reaction was completed by aging at 80 ° C. for 3 hours. Next, put the contents of the flask at 40 ° C.
After cooling to room temperature, ammonia water was added to carry out a neutralization reaction, and after completion of the reaction, vigorous stirring was carried out to produce an adhesive for use in the present invention.

(Preparation of Adhesive Sheet) Commercially available clay-coated release paper was coated with the above adhesive at a dry weight of 22 g / m ² and dried, and the adhesive layer surface and a commercially available polylactic acid film ( Product name: Lacty, made by Shimadzu) Adhesive sheet was created by bonding the back side.

Example 2 (Synthesis of carboxylic acid-modified rosin ester) Example 1 except that 60 g of acrylic acid was used instead of methacrylic acid and 140 g of adipic anhydride was used instead of glutaric anhydride.
A carboxylic acid-modified rosin ester represented by the following [Chemical Formula 4] was synthesized in the same manner as in.

[0045]

[Chemical 4]

(Production of pressure-sensitive adhesive) First, a carboxylic acid-modified rosin ester represented by [Chemical Formula 4] as an emulsified monomer mixture liquid: 6
0 parts Methoxydiethylene glycol methacrylate: 60 parts Butyl acrylate: 100 parts 2-Ethylhexyl acrylate: 100 parts Acrylic acid: 40 parts Dimethylaminoethyl methacrylate: 40 parts Anionic emulsifier (trade name: Emal NC-35, Kao) (Manufactured by the company): 6 parts Ion-exchanged water: 150 parts were mixed to prepare. Then, an adhesive was produced in the same manner as in Example 1. (Preparation of pressure-sensitive adhesive sheet) A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above pressure-sensitive adhesive was used.

Example 3 (Production of pressure-sensitive adhesive) First, a carboxylic acid-modified rosin ester represented by [Chemical Formula 3]: 2 was prepared as an emulsified monomer mixed liquid.
8 parts methoxydiethylene glycol methacrylate: 152
Parts Butyl acrylate: 40 parts 2-Ethylhexyl acrylate: 100 parts Acrylic acid: 60 parts Dimethylaminoethyl methacrylate: 20 parts Anionic emulsifier (trade name: Emal NC-35, manufactured by Kao): 6 parts Ions Exchanged water: Prepared by mixing 150 parts. Then, an adhesive was produced in the same manner as in Example 1. (Preparation of pressure-sensitive adhesive sheet) A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above pressure-sensitive adhesive was used.

Example 4 An adhesive sheet was prepared in the same manner as in Example 1 except that the following base materials were used as the release sheet. (Preparation of Release Sheet) As coating liquid, kaolin (trade name: UW-90, manufactured by EMC): 15 parts, phosphate esterified starch (trade name: Neil gum A-55C, manufactured by Abbe Co.): 5 parts, Polyvinyl alcohol (Product name: Kuraray P
VA-103, manufactured by Kuraray Co., Ltd .: 80 parts, dispersant (trade name: Aron A-9, manufactured by Toagosei Chemical Industry Co., Ltd.): 0.1 part, so that the solid content concentration is 40%. Was mixed and prepared on a commercially available high-quality paper having a weight of 64 g / m ² to obtain a dry weight of 5 g / m ^2, and dried to form a sealing layer. Then, smoothing was performed with a super calender to obtain a release substrate.

Next, a solvent type silicone release agent (trade name: LTC-3) was applied on the sealing layer of the release substrate thus obtained.
00B, manufactured by Toray Dow Corning Co., Ltd .: 100 parts, catalyst (trade name: SRX-212, manufactured by Toray Dow Corning Co., Ltd.): 0.8 parts, so that the dry weight becomes 1.0 g / m ² , It heat-cured and the release sheet was obtained.

Example 5 As a base material of a release sheet, a commercially available kraft paper having a basis weight of 72 g / m ² was laminated with polylactic acid (trade name: Lacty, manufactured by Shimadzu Corporation) to a thickness of 20 μm. An adhesive sheet was prepared in the same manner as in Example 4 except that the material was used.

Example 6 An adhesive sheet was prepared in the same manner as in Example 4 except that a commercially available polylactic acid film (trade name: Lacty, manufactured by Shimadzu Corporation) was used for both the surface substrate and the release substrate.

Example 7 (Production of pressure-sensitive adhesive) A carboxylic acid-modified rosin ester represented by [Chemical Formula 3] as an emulsion monomer mixture liquid: 1
50 parts Phenoxydiethylene glycol acrylate: 20 parts Butyl acrylate: 60 parts 2-Ethylhexyl acrylate: 100 parts Acrylic acid: 50 parts Dimethylaminoethyl methacrylate: 20 parts Anionic emulsifier (trade name: Emal NC-35, Kao) (Manufactured by the company): 6 parts Ion-exchanged water: 150 parts were mixed to prepare. Then, an adhesive was produced in the same manner as in Example 1. (Preparation of pressure-sensitive adhesive sheet) A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above pressure-sensitive adhesive was used.

Example 8 (Production of Adhesive) Carboxylic acid-modified rosin ester represented by [Chemical Formula 3] as an emulsified monomer mixture liquid: 6
0 parts Phenoxydiethylene glycol acrylate: 70 parts Butyl acrylate: 60 parts 2-Ethylhexyl acrylate: 100 parts Acrylic acid: 80 parts Dimethylaminoethyl methacrylate: 30 parts Anionic emulsifier (trade name: Emal NC-35, Kao) (Manufactured by the company): 6 parts Ion-exchanged water: 150 parts were mixed to prepare. Then, an adhesive was produced in the same manner as in Example 1. (Preparation of pressure-sensitive adhesive sheet) A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above pressure-sensitive adhesive was used.

Example 9 (Production of adhesive) Carboxylic acid-modified rosin ester represented by [Chemical Formula 3] as an emulsified monomer mixture liquid: 8
0 parts Phenoxydiethylene glycol acrylate: 20 parts Butyl acrylate: 100 parts 2-Ethylhexyl acrylate: 140 parts Acrylic acid: 20 parts Dimethylaminoethyl methacrylate: 40 parts Anionic emulsifier (trade name: Emal NC-35, Kao) (Manufactured by the company): 6 parts Ion-exchanged water: 150 parts were mixed to prepare. Then, an adhesive was produced in the same manner as in Example 1. (Preparation of pressure-sensitive adhesive sheet) A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above pressure-sensitive adhesive was used.

Example 10 (Preparation of Surface Substrate) 100 g of D, L-lactide, 0.01% by weight of stannous octoate and 0.03% by weight of lauryl alcohol were placed in a glass polymerization tube and vacuumed for 1 hour. After degassing, the tube was sealed. This mixture sealed tube at 200 ° C, 4
After heating for a period of time to cause ring-opening polymerization, poly (D,
L-lactic acid) was obtained. The average molecular weight of the obtained resin was 30,000. The obtained resin is pelletized using a twin-screw extruder, then melt-extruded using a single-screw extruder,
A film having a thickness of 50 to 60 μm was obtained. (Preparation of adhesive sheet) Other than using the surface base material,
An adhesive sheet was obtained in the same manner as in Example 1.

Comparative Example 1 Example 1 except that a commercially available polyethylene terephthalate film (manufactured by Toyobo Co., Ltd.) was used as the surface substrate.
A pressure-sensitive adhesive sheet was prepared in the same manner as.

Comparative Example 2 (Production of pressure-sensitive adhesive) A carboxylic acid-modified rosin ester represented by [Chemical Formula 3] as an emulsified monomer mixture liquid: 1
0 parts Methoxydiethylene glycol methacrylate: 60 parts Butyl acrylate: 60 parts 2-Ethylhexyl acrylate: 200 parts Acrylic acid: 20 parts Dimethylaminoethyl methacrylate: 30 parts Anionic emulsifier (trade name: Emal NC-35, Kao) (Manufactured by the company): 6 parts Ion-exchanged water: 150 parts were mixed to prepare. Then, an adhesive was produced in the same manner as in Example 1. (Preparation of pressure-sensitive adhesive sheet) A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above pressure-sensitive adhesive was used.

Comparative Example 3 (Production of pressure-sensitive adhesive) A carboxylic acid-modified rosin ester represented by [Chemical Formula 3]:
80 parts Methoxydiethylene glycol methacrylate: 10 parts Butyl acrylate: 50 parts 2-Ethylhexyl acrylate: 60 parts Acrylic acid: 10 parts Dimethylaminoethyl methacrylate: 90 parts Anionic emulsifier (trade name: Emal NC-35, Kao) (Manufactured by the company): 6 parts Ion-exchanged water: 150 parts were mixed to prepare. Then, an adhesive was produced in the same manner as in Example 1. (Preparation of pressure-sensitive adhesive sheet) A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above pressure-sensitive adhesive was used.

Comparative Example 4 (Production of Pressure-Sensitive Adhesive) A carboxylic acid-modified rosin ester represented by [Chemical Formula 3] as an emulsified monomer mixture liquid: 1
0 part Methoxydiethylene glycol methacrylate: 180
Parts Butyl acrylate: 30 parts 2-Ethylhexyl acrylate: 30 parts Acrylic acid: 140 parts Dimethylaminoethyl methacrylate: 10 parts Anionic emulsifier (trade name: Emal NC-35, manufactured by Kao): 6 parts Ions Exchanged water: Prepared by mixing 150 parts. Then, an adhesive was produced in the same manner as in Example 1. (Preparation of pressure-sensitive adhesive sheet) A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the above pressure-sensitive adhesive was used.

Comparative Example 5 As an adhesive, an acrylic adhesive (trade name: Nikazol L-145, manufactured by Nippon Carbide Industry Co., Ltd.) insoluble in water and an aqueous alkaline solution was applied to a dry weight of 22 g / m ^2. A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the adhesive sheet was dried.

Comparative Example 6 A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that a commercially available water-soluble film (trade name: Flexine, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as the surface substrate.

The pressure-sensitive adhesive sheet obtained as described above was subjected to the following evaluation tests, and the results obtained are summarized in Table 1.

(Evaluation test items) [Adhesive force] The adhesive force to the SUS plate and the glass plate was measured according to the method for measuring the normal adhesive force of JIS Z-0237. (Unit: g / 25mm)

[Evaluation of Recyclability] In the form of a pressure-sensitive adhesive sheet including a release sheet, the pressure-sensitive adhesive sheet itself was used as a sample for evaluation in consideration of mixing in the used paper recycling process. 1500 ml of water was added to 45 g of a sample obtained by cutting the sheet into a size of about 20 mm square, and 1 g of NaOH was added, and the mixture was subjected to 150,000 rotations with a TAPPI disintegrator and then dehydrated with a 60-mesh nylon screen to remove the residue. Disperse again in 5000 ml of water and add 18% N.
1.5 g of aOH aqueous solution, deinking agent (trade name: DI-60
0, manufactured by Kao Co., Ltd.) and added with 1.8 g each of 10% concentration solution, and then stirred for 120 minutes while maintaining the temperature at 55 ° C.

Next, this dispersion liquid was mixed with a floatator to 1
Float separation treatment for 0 minutes, remove the bubbles generated at that time with a scraper, dehydrate again with a 60 mesh nylon screen, wash with 1000 ml of water, disperse the remaining material in 4500 ml of water and make a handmade sheet Then, the residual state of the undisaggregated material was visually observed and judged according to the following evaluation criteria. (Criteria for evaluating recyclability) ⊚: There are almost no undisintegrated substances. ◯: There is a slight amount of undisintegrated matter, but there is no problem in practical use. X: Undisaggregated material is noticeable.

[Adhesiveness Appropriate] After applying an adhesive to the release agent layer side of the release sheet and drying it with a dryer, one side of the adhesive side and one side of the surface base material are attached and firmly fixed. Then, while pulling the surface base material, the pressure-sensitive adhesive layer and the back surface of the surface base material are attached to each other to form an adhesive sheet, and wrinkles are generated on the surface base material due to heat shrinkage, or the surface due to elasticity or elongation of the surface base material. Occurrence of wrinkles on the substrate was judged according to the following evaluation criteria. (Appropriate Evaluation Criteria for Adhesive Processing) O: Wrinkles do not occur on the surface substrate after the adhesive sheet is prepared. Δ: After the pressure-sensitive adhesive sheet is produced, some wrinkles are generated on the surface base material. X: Wrinkles are generated on the surface substrate after the pressure-sensitive adhesive sheet is produced.

[0067]

[Table 1]

[0068]

As shown in Table 1, the pressure-sensitive adhesive sheet of the present invention does not cause wrinkles during production and has a necessary adhesive force when it is attached, even though the film is used as the surface substrate. The pressure-sensitive adhesive sheet was easily decomposed or dispersed even after being used or when it was left unused and mixed into a recycled paper recycling process, and was removed outside the process.

Claims (2)

[Claims] 1. A pressure-sensitive adhesive sheet comprising a release sheet, a pressure-sensitive adhesive layer, and a surface base material laminated, wherein the surface base material is a film made of a lactic acid-based polymer and having a dissociation property with respect to an alkaline aqueous solution. The adhesive constituting the agent layer is a copolymer obtained by neutralizing a carboxylic acid-modified rosin-containing acrylic ester copolymer having the following composition with an alkaline substance, and having re-degradability with respect to water or an alkaline aqueous solution. An adhesive sheet characterized by being an agent. (A) a carboxylic acid-modified rosin ester monomers .. 5 to 40 wt% (b) (poly) ethylene glycol (meth) acrylate monomers .. 5 to 40 wt% (c) (meth) C ₄ -C ₁₈ acrylic acid Alkyl ester monomer: 30 to 60% by weight (d) Ethylenically unsaturated carboxylic acid-containing monomer: 5 to 20% by weight (e) Monomer copolymerizable with the above a, b, c and d :: 5 to 20 weight% 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the release sheet is made of a base material having re-degradability with respect to water or an aqueous alkaline solution.