JPH06330001A - Degradable tacky film - Google Patents

Abstract

PURPOSE:To obtain a degradable tacky film useful for protecting the surface of automobiles, having properties degradable under a natural condition and a simplified process by providing one side of a base film prepared from a lactic acid-based polymer with a tacky agent layer. CONSTITUTION:One side of a base film prepared from a lactic acid-based polymer is provided with a tacky agent layer to give the objective film. The polymer is either a polylactic acid or a lactic acid-hydroxycarboxylic acid copolymer and has preferably 30,000-500,000 molecular weight. The polylactic acid is either a poly(L-lactic acid) or poly(DL-lactic acid) having 50-100mol% L-lactic acid unit or a poly(D-lactic acid) or poly(DL-lactic acid) having 50-100mol% D-lactic acid unit.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a degradable adhesive film. Specifically, stainless steel, aluminum and other metal plates or processed products, resin-coated wood boards, decorative boards,
Surface and degradable adhesive film for surface protection that is temporarily attached to the surface of adherends such as wooden and metal furniture and automobile bodies to be used for surface protection, and the surface (surface) on the side where integrated circuits of semiconductor wafers are incorporated Degradable adhesive film for semiconductor wafer processing, which is used for protection when the other surface (back surface) of the semiconductor wafer is ground or dicing, and display degradability that is printed or painted on the film surface. The present invention relates to an adhesive film and a degradable adhesive film used as a self-adhesive tape for binding vegetables and for stationery.

[0002]

2. Description of the Related Art Conventionally, surfaces of metal plates such as stainless steel and aluminum or processed products thereof, resin-coated wood boards, decorative boards, wooden and metal furniture, measuring instruments such as watches, and adherends such as automobile bodies. Adhesive film for surface protection that is temporarily attached to the surface of the semiconductor wafer, and is attached to the surface of the semiconductor wafer on which the integrated circuit is incorporated, and is protected when grinding or dicing the other surface (back surface) of the semiconductor wafer. Adhesive film for semiconductor wafer processing, used for
As an adhesive film used as an adhesive film for display which is printed or painted on the film surface, polyvinyl chloride, polyolefin, ethylene-vinyl acetate copolymer film or the like is used as a base film, and an adhesive layer is provided on the surface thereof. Adhesive films or tapes are widely used.

For example, Japanese Unexamined Patent Publication (Kokai) No. 2-107684 discloses a surface protective film having a pressure-sensitive adhesive layer provided on one side of a soft vinyl chloride resin film containing a polymer plasticizer having a molecular weight of 500 or more, In addition, JP-A-61-1
No. 0242 (US Pat. Nos. 4,853,286 and 4,928,438) disclose base film such as ethylene-vinyl acetate copolymer film or polybutadiene film having Shore D type hardness of 40 or less. Disclosed is an adhesive film for wafer processing, characterized in that an adhesive is provided on the surface of the.

Japanese Patent Laid-Open No. 2-300281 discloses that a new automobile (four-wheeled or two-wheeled vehicle) (painted vehicle) may be exposed to rain, dust, dust, or sea breeze during transportation or storage until it reaches consumers. A protective pressure-sensitive adhesive film that is temporarily attached to the surface of a body of an automobile or the like for the purpose of preventing corrosion deterioration has been disclosed. As the adhesive film for protecting automobiles, a polyolefin film such as polyethylene or polypropylene, a polyvinyl chloride film or the like coated with an adhesive on one side is used.

Films made of polyvinyl chloride, polyolefin, etc. have been conventionally used for displaying, displaying, advertising, advertising, etc. by displaying characters, patterns, etc. on signboards, walls, etc., or for decorating car bodies, structures, etc. In addition, a method of sticking a printed, transferred or painted character, pattern, design or the like on the adherend is widely used.

Due to the nature of the purpose of use, the above-mentioned various surface-protective pressure-sensitive adhesive films are attached to an adherend for a predetermined period of time to protect the surface thereof, and in most cases they are peeled off and discarded. However, the base film used for these conventional pressure-sensitive adhesive films, as described above, does not decompose in a natural environment such as polyvinyl chloride, polyolefin, ethylene-vinyl acetate copolymer or has a remarkably low decomposition rate. Therefore, if it is buried after use, it will remain in the soil semipermanently. Also, when dumped in the ocean, it may damage the landscape and destroy the living environment of marine life, and waste treatment has become a social problem. Further, when incinerated, a large amount of energy is required for incineration, and particularly polyvinyl chloride has a problem of generating a toxic gas.

Conventionally, lactic acid-based polymers have been known as degradable polymers. For example, Japanese Patent Publication Sho 49-36
Japanese Patent No. 597 discloses a surgical aid obtained from a lactic acid-glycolic acid copolymer composed of lactic acid units of 65 to 85% by weight and glycolic acid units of 35 to 15% by weight, and Japanese Patent Publication No. 62-501611 discloses a medical transplant base material obtained from a copolymer of caprolactone and lactide (a cyclic dimer of lactic acid).

Lactic acid-based polymers such as polylactic acid or lactic acid-hydroxycarboxylic acid copolymer are effectively hydrolyzed even by moisture in the air, and when used outdoors, they are used indoors, in the dark, or in vivo. As compared with the case where it is treated, the strength is reduced more quickly, and phenomena such as embrittlement, fracture, and disappearance may occur earlier than expected. Therefore, the lactic acid-based polymer has a problem in that it is mainly used as a material for molded articles used outdoors.

When it is used outdoors, it decomposes faster than the expected decomposition time, when it is attempted to use a degradable molded article made of a lactic acid-based polymer such as polylactic acid or lactic acid-hydroxycarboxylic acid copolymer as a material. Sometimes it can bring serious consequences, a major drawback that can never be overlooked.

[0010]

There are various findings regarding the hydrolysis rate of polylactic acid and lactic acid-hydroxycarboxylic acid copolymers. Therefore, when a decomposable molded article for disposable use is made using these resins, it is necessary to design the resin according to the decomposition time required for the use. For example, if the usage period is about half a year, it is preferable to use a high molecular weight poly (L-lactic acid). Also, the usage period is about several days, and it is preferable to decompose as soon as possible after use. For use, it is preferred to use lactic acid-glycolic acid copolymers.

According to the knowledge of the inventors, when a molded article made of a lactic acid-based polymer such as polylactic acid or lactic acid-hydroxycarboxylic acid copolymer is used outdoors, it is usually used indoors, in a dark place, or in vivo. It was found that the strength decreased obviously faster than that of the case, and the phenomena such as embrittlement, fracture, and disappearance occurred earlier than expected. For example, based on the knowledge of the hydrolysis rate, when a film made with the expectation of maintaining its strength for at least half a year at normal temperature was used outdoors, it became brittle in about 1 month if it was early. , No longer fulfill its function. Worse,
The extent to which this decomposition rate was accelerated was completely unexpected and its decomposition period was variable. The present invention intends to solve such a conventional problem.

That is, the object of the present invention is to solve the above-mentioned problems and to be adhered to the surface of an adherend for a predetermined period of time to serve as surface protection, display, binding, etc. of the adherend,
An object of the present invention is to provide a degradable pressure-sensitive adhesive film using as a base film a film having a property of being decomposed and disappeared in a natural environment after being discarded after use. Another object of the present invention is to provide a degradable pressure-sensitive adhesive film having excellent weather resistance and having a property of being decomposed and disappearing in a natural environment after use. Another object of the present invention is to provide a degradable pressure-sensitive adhesive film for surface protection, display, binding, stationery, etc., which uses as a base film a film that decomposes and disappears in a natural environment after use.

[0013]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a film containing a lactic acid-based polymer as a main component is used as a base film, and an adhesive is provided on one side of the base film. It has been found that a degradable adhesive film can be obtained by providing a layer.

That is, according to the present invention, there is provided a degradable pressure-sensitive adhesive film having a pressure-sensitive adhesive layer provided on one surface of a substrate film obtained from a lactic acid-based polymer.

The degradable pressure-sensitive adhesive film of the present invention is produced by applying a pressure-sensitive adhesive to one surface of a lactic acid-based polymer film obtained by molding a lactic acid-based polymer and drying it to form a pressure-sensitive adhesive layer. In addition, at least one surface of a base film obtained from a lactic acid-based polymer is printed, painted, etc., and is marked with characters, patterns, seals, marks, etc., and is used as a base film, and one surface of the base film is used. By providing the pressure-sensitive adhesive layer in the same manner as above, the degradable pressure-sensitive adhesive film for display is manufactured.

These degradable pressure-sensitive adhesive films maintain a certain strength for a predetermined period of time, and when they are discarded after use, they are hydrolyzed in a natural environment. Therefore, it does not accumulate as waste. Further, it is a degradable pressure-sensitive adhesive film having the same level of adhesive strength as conventional ones. Therefore, metal plate or its processed product, resin coated wood board, decorative board,
An integrated circuit of a semiconductor wafer was incorporated as a surface protective degradable adhesive film that was temporarily attached to the surface of adherends such as wooden and metal furniture, measuring instruments such as watches, and automobile bodies. As a degradable adhesive film for semiconductor wafer processing, which is attached to the side surface and is used for protection when grinding or dicing the other surface (back surface) of the semiconductor wafer, or the surface of the film is printed or painted. As a degradable adhesive film for display, other,
It is useful as a self-adhesive tape for binding vegetables, a self-adhesive tape for stationery, and the like.

The present invention will be described in detail below. In the present invention, the lactic acid-based polymer refers to polylactic acid and lactic acid-hydroxycarboxylic acid copolymer, which is already known as a bioabsorbable polymer. The lactic acid-hydroxycarboxylic acid copolymer preferably used is
It is a copolymer of lactic acid or lactide with hydroxycarboxylic acid or a cyclic dimer thereof. In addition, although L-form and D-form exist in lactic acid, in the present invention, when simply referred to as lactic acid, L-form and D-form are used unless otherwise specified.
We will refer to both the body and the body. The molecular weight of a polymer refers to the weight average molecular weight unless otherwise specified.

The polylactic acid used in the present invention includes poly (L-lactic acid) whose constituent unit is L-lactic acid only, poly (D-lactic acid) only D-lactic acid, and L-lactic acid unit and D-lactic acid. Lactic acid units and poly (DL-
Any of lactic acid) can be used. Lactic acid used in the present invention
Examples of the hydroxycarboxylic acid which is a comonomer of the hydroxycarboxylic acid copolymer include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid and hydroxyheptanoic acid.

The polylactic acid and lactic acid-hydroxycarboxylic acid copolymer used in the present invention are L-lactic acid and D-lactic acid.
It can be obtained by selecting a necessary one from lactic acid and hydroxycarboxylic acid as a raw material monomer and performing dehydration polycondensation. Examples of the dehydration polycondensation method include a heat dehydration condensation reaction of lactic acid or lactic acid and other hydroxycarboxylic acids, preferably a method of performing the reaction in an organic solvent while removing generated water out of the reaction system.

Further, lactide which is a cyclic dimer of lactic acid,
It can also be obtained by ring-opening polymerization of cyclic esters such as glycolide, caprolactone, propiolactone, butyrolactone, and valerolactone, which are cyclic dimers of glycolic acid.

A molded product obtained from a lactic acid-based polymer is hydrolyzed not only in water or soil after disposal, but also by water in the air, rainwater or the like not only in the period of use. Therefore, the molecular weight of the lactic acid-based polymer is related to the properties such as the tensile strength of the base material film. When the molecular weight is low, the tensile strength decreases, and when it is high, the tensile strength improves. However, if it is too high, the molding processability tends to decrease, and it tends to be difficult to form a film.
From this viewpoint, the molecular weight of the lactic acid-based polymer used in the present invention is preferably in the range of 10,000 to 1,000,000. More preferably 30,000 to 5
It is 0,000.

When the lactic acid-based polymer is polylactic acid, when a sheet or film is molded by melt extrusion molding, calender molding or the like, and heat-treated such as heat setting under heating, crystallization sometimes progresses. The transparency of the molded product may be lost. Specifically, in the case of poly (L-lactic acid) having 100 mol% of L-lactic acid unit and 100 mol% of D-lactic acid unit, in order to obtain a transparent molded article, It is necessary to perform the heat treatment such as heat setting at a low temperature of about 60 to 90 ° C., which has a drawback that the temperature range of the forming process is narrow.

In consideration of these points, in order to obtain a transparent molded product, L (lactic acid) is more preferable than poly (L-lactic acid) consisting of L-lactic acid units or poly (D-lactic acid) consisting only of D-lactic acid units. -Poly (DL-lactic acid) consisting of lactic acid unit and D-lactic acid unit is preferred. Specifically, the polylactic acid preferably used has a weight average molecular weight of 30,000.
Is about 500,000, and the L-lactic acid unit is about 50 to
100 mol% (more preferably 70-100 mol%)
Poly (L-lactic acid) and poly (DL-lactic acid) having D-lactic acid units of 50 to 100 mol% (more preferably 70 to 100 mol%) and poly (DL-lactic acid). ).

When the lactic acid-based polymer is a lactic acid-hydroxycarboxylic acid copolymer, the degradability is affected by the content of lactic acid units. When the content of lactic acid unit is low, when it is discarded after use, the decomposition may be very slow or the decomposition may be insufficient. From this viewpoint, the content of lactic acid units in the copolymer is preferably 10 mol% or more.

Specifically, the preferred lactic acid-glycolic acid copolymer has a weight average molecular weight of 30,000 to 50.
A copolymer having a lactic acid unit of 30 to 98 mol% and a glycolic acid unit of 2 to 70 mol%. A more preferable composition is 70 to 98 mol% of lactic acid unit.
And a copolymer with 2 to 30 mol% glycolic acid units. A preferred lactic acid-hydroxycaproic acid copolymer has a weight average molecular weight of 30,000 to 50.
A copolymer having a lactic acid unit of 10 to 98 mol% and a hydroxycaproic acid unit of 2 to 90 mol%. A more preferable composition is 20 to 9 lactic acid units.
It is a copolymer with 8 mol% and hydroxycaproic acid units 2-80 mol%.

The optimum molecular weight and copolymer composition of the lactic acid-based polymer used in the present invention are appropriately selected from the above range according to the longest application period in the intended use. For example, based on the findings of the present inventors, it is preferable to use poly (L-lactic acid) having a molecular weight of 150,000 or more when the usage period is six months or more. For example, when the usage period is about 1 month, poly (L-lactic acid) having a molecular weight of 50,000 or more or poly (DL-lactic acid) having a molecular weight of 100,000 or more and less than 5 mol% of D-lactic acid units is used. ) Is preferably used. When the use period is only several days to several weeks, poly (DL-lactic acid) containing less than 25 mol% of D-lactic acid unit or lactic acid-glycolic acid containing less than 15 mol% of glycolic acid unit in addition to the above-mentioned polymer. Copolymers are preferably used. Further, when a highly flexible molded product is required, for example, a lactic acid-hydroxycaproic acid copolymer containing about 60 mol% of hydroxycaproic acid units can be used to obtain a molded product suitable for about 3 months. To be

The degradable pressure-sensitive adhesive film of the present invention comprises a base film made of the above-mentioned lactic acid-based polymer, which is formed by a known film-forming method such as solution casting method, melt extrusion method, calender method or inflation method. It can be obtained by providing an adhesive layer on one surface of the base film.

Since the degradable pressure-sensitive adhesive film is often used outdoors, it is preferable to add an ultraviolet absorber or a light stabilizer to the base film. Also,
It is preferable to use a highly flexible base film to which a plasticizer is added depending on the application. In addition, if necessary,
Other additives such as antioxidants, heat stabilizers, lubricants, pigments and colorants may be added.

When the substrate film contains an ultraviolet absorber or a light stabilizer, it is selected from an ultraviolet absorber and a light stabilizer with respect to 100 parts by weight of a lactic acid-based polymer obtained by ring-opening polymerization or dehydration polycondensation. 0.001-5 parts by weight of at least one additive, more preferably 0.05-
Add 5 parts by weight and mix. When the addition amount of the ultraviolet absorber and the light stabilizer is small, the weather resistance when the degradable adhesive film is used outdoors, that is, the effect of suppressing the promotion of decomposition due to ultraviolet exposure is not sufficiently recognized, and If the amount is too large, the characteristics originally possessed by the lactic acid-based polymer are likely to be impaired. Considering this, the addition amount of the ultraviolet absorber and the light stabilizer is preferably within the above range.

The ultraviolet absorbers and light stabilizers used in the present invention include phenyl salicylate and p-tert-
Salicylic acid derivatives such as butylphenyl salicylate,

2,4-dihydroxybenzophenone, 2
-Hydroxy-4-methoxybenzophenone, 2,2 '
-Dihydroxy-4-methoxybenzophenone, 2,
2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2,2 ', 4,4'-tetra Benzophenones such as hydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone and bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane,

2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'- Hydroxy-3'-ter
t-Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'
-Di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-ter
t-octylphenyl) benzotriazole, 2-
(2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2- [2'-hydroxy-3'-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2,2′-methylenebis [4- (1,
1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] and the like, benzotriazoles,

Trade name Sanduvor EPU and Sand
oxalic acid anilide derivative known as uvorVSU, 2-
Ethoxy-5-tert-butyl-2′-ethyloxalic acid bisanilide, 2-ethoxy-2-ethyloxalic acid bisanilide, 2,4-di-tert-butylphenyl-3,5-
Di-tert-butyl-4-hydroxybenzoate,
2-Ethylhexyl-2-cyano-3,3-diphenyl acrylate, 1,3-bis- (4-benzoyl-3-
Hydroxyphenoxy) -2-propyl acrylate,
1,3-Bis- (4-benzoyl-3-hydroxyphenoxy) -2-propyl methacrylate, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, methyl ortho-benzoylbenzoate, ethyl-2-cyano-3 , 3-diphenyl acrylate, 2-hydroxy-
Known as 4-benzyloxybenzophenone, nickel dibutyldithiocarbamate, nickel-cytobisphenol complex, nickel-containing organic light stabilizer, barium, sodium, phosphorus-containing organic / inorganic complex, semicarbazone light stabilizer, trade name Sanshade, etc. Zinc oxide UV stabilizers and synergists,

Bis (2,2,6,6-tetramethyl-4
-Piperidyl) sebacate, bis (1,2,2,6,6)
-Pentamethyl-4-piperidyl) sebacate, 1-
[2- {3- (3,5-di-tert-4-hydroxy-phenyl) propionyloxy} ethyl] -4- {3
-(3,5-Di-tert-butyl-4-hydroxyphenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-
Tetramethyl-3-octyl-1,2,3-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl succinate-1- (2-hydroxyethyl)
-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate,

Poly [6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-
Diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-
Tetramethyl-4-piperidyl) imino]], 2-
Bis (1,2,2,2,3-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonate
6,6-pentamethyl-4-piperidyl), tetraxy (2,2,6,6-tetramethyl-4-piperidyl)
1,2,3,4-butane tetracarboxylate, 1,
2,3,4-butanetetracarboxylic acid and 1,2,2
Condensate of 6,6-pentamethyl-4-piperidinol and tridecyl alcohol, 1,2,3,4-butanetetracarboxylic acid, 2,2,6,6-tetramethyl-4-piperidinol and tridecyl alcohol Condensate of 1,
2,3,4-butanetetracarboxylic acid and 1,2,2
6,6-pentamethyl-4-piperidinol and β, β,
β ′, β′-tetramethyl-3,9- (2,4,8,1
Condensate of 0-tetraoxaspiro [5,5] undecane) diethanol, 1,2,3,4-butanetetracarboxylic acid and 2,2,6,6-tetramethyl-4-piperidinol and β, β, β ', β'-tetramethyl-3,9-
Condensation product of (2,4,8,10-tetraoxaspiro [5,5] undecane) diethanol, 1,2,2,6
6-pentamethyl-4-piperidyl methacrylate,
Hindered amines such as 2,2,6,6-tetramethyl-4-piperidyl methacrylate may be mentioned.

[2,2'-thiobis-] known as light stabilizers such as polyethylene and polypropylene.
(4-Tert-octylphenolite)]-n-butylamine nickel and [2,2′-thiobis- (4-te
rt-octylphenolite)]-2-ethylhexylamine nickel may cause degradation of the polylactic acid and lactic acid-hydroxycarboxylic acid copolymer when mixed with the polylactic acid and lactic acid-hydroxycarboxylic acid copolymer. Is not suitable.

As a method of mixing the ultraviolet absorber and / or the light stabilizer with the lactic acid-based polymer, a predetermined amount of the ultraviolet absorber and / or the light stabilizer is added to the lactic acid-based polymer, and a ribbon blender, a Henschel mixer or the like is used. A method of mixing at a temperature near room temperature using a mixer, a method of heating and melting a lactic acid-based polymer at 100 to 280 ° C., adding a predetermined amount of an ultraviolet absorber and / or a light stabilizer, and kneading, or a lactic acid-based polymer Polymer and UV absorber and /
Alternatively, a method of dissolving and mixing the light stabilizer in a solvent such as chloroform, methylene chloride, benzene, toluene, xylene, dimethylformamide, dimethylsulfoxide, dimethylimidazolidinone and the like can be mentioned.

In the base film used in the present invention, other additives such as a plasticizer, an antioxidant, a heat stabilizer, a lubricant, a pigment and a colorant may be added, if necessary, in addition to the above ultraviolet absorber and stabilizer. It does not matter if it is mixed.

As a plasticizer, a phthalic acid derivative such as di-n-octyl phthalate, di-2-ethylhexyl phthalate, dibenzyl phthalate, diisodecyl phthalate, ditridecyl phthalate or diundecyl phthalate,
Isophthalic acid derivative such as diisooctyl phthalate, adipic acid derivative such as di-n-butyl adipate, dioctyl adipate, maleic acid derivative such as di-n-butyl maleate, citric acid derivative such as tri-n-butyl citrate, mono Itaconic acid derivatives such as butyl itaconate,
Oleic acid derivatives such as butyl oleate, ricinoleic acid derivatives such as glycerin monoricinoleate, low molecular weight compounds such as phosphate esters such as tricresyl phosphate and trixylenyl phosphate, high molecular plastics such as polyethylene adipate and polyacrylate Agents and the like. Among the above plasticizers, preferred plasticizers include glycerin triacetate (triacetin), lactic acid, lactide, lactic acid oligomers having a degree of polymerization of about 2 to 10, and the like.

When a plasticizer is added to the lactic acid type polymer,
The amount added is appropriately selected according to the flexibility required for the base film. If too much is added, bleeding out (protrusion to the surface) of the substrate film is unfavorable. Therefore, the amount of the plasticizer added is preferably 1 to 50 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of the lactic acid polymer.

When the lactic acid-based polymer contains a plasticizer, it is preferable that the polymer has low crystallinity in terms of plasticization efficiency, bleed-out prevention and the like. Therefore, when a plasticizer is added, it is preferable to use poly (DL-lactic acid) or lactic acid-hydroxy acid copolymer as the lactic acid-based polymer. More preferably, the L-lactic acid unit is 50-
Poly (DL-lactic acid) having 98 mol% and D-lactic acid unit of 2 to 50 mol%, poly (DL-lactic acid unit of 50 to 98 mol% and L-lactic acid unit of 2 to 50 mol% DL-lactic acid), 2 to 70 mol% of glycolic acid unit and lactic acid unit 3
Lactic acid-glycolic acid copolymers with 0-98 mol%, lactic acid-hydroxycaproic acid copolymers with 2-90 mol% hydroxycaproic acid units and 10-98 mol% lactic acid units are used. These polymers are effectively plasticized by the plasticizer and can prevent plasticizer bleed-out.

When the base film is produced by the solution casting method, chloroform, methylene chloride, benzene, acetonitrile, toluene, xylene, dimethylformamide, dimethylsulfoxide, dimethylimidazolidinone, etc. are used as a solvent and then smoothed. It is performed by casting on a flat surface and removing the solvent.

When the substrate film is produced by the melt extrusion method, if the kneading temperature is too low, it is difficult to obtain extrusion stability and overload tends to occur. On the other hand, if the extrusion temperature is too high, thermal decomposition of the lactic acid-based polymer will be severe, resulting in a decrease in molecular weight, a decrease in strength, coloration and the like, which is not preferable. Therefore, the kneading temperature is preferably 100 to 280 ° C, more preferably 130 to 250 ° C. The extruder die may have annular or linear slits. The temperature of the die may be similar to the kneading temperature range.

Although it is not always necessary to stretch the film after it is formed, when it is stretched, it is stretched at least 1.1 to 10 times, preferably 2 to 7 times in the uniaxial direction. The stretching temperature is selected from the range of 60 to 210 ° C. depending on the type of lactic acid polymer used. The stretching is preferably biaxial stretching from the viewpoint of the strength of the obtained film.

The thickness of the base film is 10 to 2000 μm
The thickness is about 20 to 500 μm, more preferably 100 to 300 μm. The thickness is appropriately selected depending on the application.

As a method for providing a pressure-sensitive adhesive layer on one surface of the obtained base film, a method of applying a pressure-sensitive adhesive to one surface of the base film is preferable, and a conventionally known coating method such as a roll coater method or dipping Method, brush coating method, spray method and the like. The adhesive can be applied to the whole surface or a part of the base film. The thickness of the pressure-sensitive adhesive layer is appropriately determined depending on the shape of the adherend, the surface state, the application, etc., but generally 2 to 200 μm is preferable.

After applying the adhesive, the adhesive layer is dried in a drying oven. The drying temperature at this time varies depending on the type and thickness of the base film, the composition of the pressure-sensitive adhesive, the thickness of the pressure-sensitive adhesive layer, etc., but is preferably 40 to 180 ° C. More preferably, it is 60 to 120 ° C. If the drying temperature is less than 40 ° C., it cannot be sufficiently dried, and if it exceeds 180 ° C., problems such as wrinkles occur due to shrinkage of the base film. The drying time varies depending on the composition and thickness of the base film, the type of pressure-sensitive adhesive, the thickness of the pressure-sensitive adhesive layer, etc., but is usually 2-1.
A method in which it is continuously conveyed in the drying furnace at a speed of 00 m / min and is retained in the drying furnace for 0.1 to 30 minutes is preferable.

In addition, a pressure-sensitive adhesive is applied to one surface of a film having good peelability such as a polypropylene film in advance by the above method and dried to form a pressure-sensitive adhesive layer, and then the surface of the pressure-sensitive adhesive layer is a substrate film. A method of laminating a lactic acid-based polymer film and pressing it to transfer the pressure-sensitive adhesive layer to the substrate film side can also be adopted.

As the adhesive applied to one side of the base film, a rubber-based adhesive containing natural rubber or synthetic rubber as a main component, acrylic resin-based, silicone resin-based, urethane resin-based, epoxy resin-based, melamine resin Examples thereof include synthetic resin-based pressure-sensitive adhesives containing a resin, a phenol resin-based resin, a vinyl acetate resin-based resin, etc. as a main component. Among these, an acrylic resin-based pressure-sensitive adhesive having excellent weather resistance is particularly preferable.

Examples of the acrylic resin-based pressure-sensitive adhesive include copolymers containing ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc. as a main component and other vinyl-based monomers copolymerized. Examples thereof include a solution system in which the copolymer is uniformly dissolved in an organic solvent and a water emulsion system in which the copolymer is dispersed in water in the form of particles.

Among these, the pressure-sensitive adhesive particularly preferably used is one obtained by emulsion polymerization of a monomer mixture containing an alkyl acrylate ester monomer and a monomer having a carboxyl group. Further, it is preferably obtained by emulsion polymerization of a monomer mixture in which vinyl monomers, polyfunctional monomers, internal cross-linking monomers and the like which are copolymerizable with them are mixed if necessary.

Examples of the alkyl acrylate ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, octyl acrylate, octyl methacrylate, nonyl. Examples thereof include acrylate, nonyl methacrylate, dodecyl acrylate, dodecyl methacrylate, and the side chain alkyl group may be linear or branched. Further, two or more of the above alkyl acrylate ester monomers may be used in combination depending on the purpose.

Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid,
Examples thereof include itaconic acid, maleic acid and fumaric acid.
This monomer is preferably copolymerized in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the acrylic resin emulsion pressure-sensitive adhesive constituent monomer. Since the carboxyl group in the pressure-sensitive adhesive reacts with the cross-linking agent described later to form a cross-linked structure, when the amount of the monomer having a carboxyl group in the pressure-sensitive adhesive is small, a sufficient cross-linked structure is not formed. However, the cohesive force becomes insufficient, and the non-transferability of the pressure-sensitive adhesive to the adherend decreases. On the other hand, if the amount is too large, the reaction system during emulsion polymerization becomes unstable, which is not preferable. From this viewpoint, the above range is preferable.

Examples of the vinyl monomer copolymerizable with the acrylic acid alkyl ester monomer and the carboxyl group-containing monomer include, for example, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, acrylamide, methacrylamide, and dimethylamino acrylate. , Dimethylaminomethacrylate, vinyl acetate, styrene, acrylonitrile and the like.

If necessary, a crosslinking agent, a surfactant, an organic solvent or the like can be added to the adhesive. The surface active agent is preferably a nonionic surface active agent in order to prevent contamination and corrosion of the adherend. The addition amount is 0.01 to 50 parts by weight, preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the adhesive.
0 parts by weight. Addition of a surfactant has the effect of improving the coatability and preventing an increase in the adhesive strength with time after sticking to an adherend.

As a cross-linking agent, sorbitol polyglycidyl ether, polyglycol polyglycidyl ether,
Pentaerythritol polyglycidyl ether, epoxy resin such as trimethylolpropane polyglycidyl ether, methylolated melamine, alkyl etherified melamine, melamine-urea co-condensate, alkyl etherified methylol group-containing urea-formaldehyde initial condensate,
Melamine resins such as guanamine resin, 1,1 ′-(methylene-di-p-phenylene) bis-3,3′-aziridinyl urea, 1,1 ′-(hexamethylene) bis-3,
3'-aziridinylurea, ethylenebis- (2-aziridinylpropionate), tris (1-aziridinyl)
Phosphine oxide, 2,4,6-triaziridinyl-1,3,5-triazine, trimethylolpropane-
Examples include aziridine resins such as tris- (2-aziridinylpropionate).

The cross-linking agent is added alone when it is water-soluble, and when it is water-insoluble, it is dissolved in a small amount of alcohols or acetones and added to the acrylic resin. Further, for the purpose of accelerating the crosslinking reaction, it is possible to add an accelerator such as organic tin, organic lead, organic cobalt, amines and the like. The addition amount of the crosslinking agent varies depending on the type of the crosslinking agent used and the type of the pressure-sensitive adhesive layer, but is preferably 0.01 to 20 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive. If the amount added is less than 0.01 parts by weight, a sufficient crosslinking reaction will not occur. Also, the upper limit does not need to be added in excess of 20 parts by weight, considering the number of functional groups that cause a crosslinking reaction in the pressure-sensitive adhesive layer. Since the addition of the cross-linking agent increases the molecular weight of the pressure-sensitive adhesive, it is possible to suppress the time-dependent increase in the adhesive strength after being adhered to the adherend, and when the pressure-sensitive adhesive is peeled from the adherend It is possible to prevent the transfer.

The degradable pressure-sensitive adhesive film of the present invention can be not only physically and mechanically peeled after being adhered to an adherend for a predetermined period of time, but also decomposed and removed using an alkali or an acid. Examples of preferably used acids include hydrochloric acid and sulfuric acid. Moreover, sodium hydroxide, potassium hydroxide, etc. are illustrated as an alkali preferably used.
Particularly preferred is an aqueous solution of sodium hydroxide. At this time, heating may be performed to promote decomposition and removal. For example, the substrate film can be almost completely removed by treating with 1N aqueous sodium hydroxide solution at 60 ° C. for about 1 hour.

The degradable pressure-sensitive adhesive film of the present invention is a metal plate containing stainless steel, aluminum or the like or a processed product thereof, a synthetic resin plate, a synthetic resin molded processed product, a resin-coated wooden board, a decorative wooden board, wooden and metal furniture, a watch. It can be used as a degradable pressure-sensitive adhesive film for surface protection when transporting, storing, processing, etc. of measuring instruments such as.

When the automobile or the like is transported or stored, in particular, when it is transported by sea by sea, the degradable pressure-sensitive adhesive film of the present invention can be used as a corrosion preventive instead of a protective coating for preventing corrosion by sea breeze or the like. it can. This not only eliminates the need for protective coating for transportation and storage, but also eliminates the work of removing the protective coating using a solvent or the like.

Further, as an adhesive film for preventing damage to a semiconductor wafer when it is attached to the surface (front surface) of the semiconductor wafer on which the integrated circuit is incorporated and the other surface (rear surface) of the semiconductor wafer is ground or diced. Can be used. That is, after the integrated circuit is incorporated in the semiconductor wafer, the degradable adhesive film of the present invention is attached to the surface (front surface) of the semiconductor wafer on which the integrated circuit is incorporated, and then the other surface of the semiconductor wafer ( Grind or dice the back side). Since the stress generated by grinding or dicing is absorbed by the decomposable adhesive film, the semiconductor wafer can be prevented from being damaged.

In addition to the above-mentioned uses, the degradable adhesive film of the present invention is a self-degrading self-adhesive tape for binding, a self-degrading self-adhesive tape for stationery that bundles vegetables such as spinach and green onions by cutting into a width of about 5 to 50 mm. It can be used as a tape or the like.

Further, after the lactic acid-based polymer is formed into a film by the above-mentioned method, the surface thereof is subjected to printing, painting, etc., and then an adhesive material layer is provided on one surface of the film by the above-mentioned method, whereby the degradability for display is obtained. An adhesive film is obtained. The film surface on which printing, painting, etc. are applied may be the surface on which the adhesive material layer is provided, the surface on which the adhesive material layer is not provided, or both surfaces. Moreover, you may print, paint, etc. on the other surface of the degradable adhesive film which has an adhesive material layer on one surface obtained by the said method.

Specific examples of printing, painting, etc. applied to the degradable pressure-sensitive adhesive film for display of the present invention include display, display,
Examples include advertisements, letters for advertising, designs, designs, seals, marks, and the like. Even if these are drawn by hand,
It may be mechanically printed. Further, instead of letters, designs, etc., the whole or a part of the base film may be coated with paints of various colors, or the designs may be drawn and used as a degradable adhesive film for decoration.

The degradable adhesive film for display, which has been printed or painted as described above, is attached to the wall surface of a signboard, a building, etc. through an adhesive layer, and posted, displayed, advertised, advertised, etc. Therefore, the work of directly painting on the walls of signboards, buildings, etc. is omitted, and it is possible to efficiently and easily display on many places. The same applies to the case where the surface decoration of a car body, a building or the like is performed.

For printing or painting, known materials such as paints, dyes, inks, pigments, and black inks can be used.
For example, ink for offset printing, ink for gravure printing (for polyethylene terephthalate, polyvinyl chloride, polystyrene), black ink, paint, UV ink, heat set ink, black ink, red ink and the like can be mentioned.

Among the above inks and paints, an oil-based ink or an oil-based ink using a solvent that dissolves a lactic acid-based polymer, such as chloroform, methylene chloride, benzene, toluene, xylene, dimethylformamide, dimethylsulfoxide, dimethylimidazolidinone. Paint is not preferred.

The lactic acid-based polymer film used in the present invention is mainly composed of a lactic acid-based polymer having an ester group in its molecular structure, and has good coatability for adhesives and paints, and good printability with ink and the like. is there. Therefore, for example, corona discharge treatment or the like which is usually performed on polyolefin films, ethylene-vinyl acetate copolymer films, polybutadiene films and the like is not required to improve the coatability and printability.

[0069]

EXAMPLES The present invention will be described in more detail below with reference to examples. Preparation Examples 1 to 9 <Preparation of lactic acid-based polymer by ring-opening polymerization> Commercially available L-lactide (hereinafter referred to as L-LTD) and DL-lactide (D-form 50 mol / L-form 50 mol, hereinafter DL-). LT
D) and glycolide (hereinafter referred to as GLD)
Each was purified by recrystallization four times using ethyl acetate. Commercially available ε-caprolactone (hereinafter, referred to as CL) was dried over calcium hydride and then distilled for purification.
In a glass reaction vessel whose surface was treated with silane, the L-LTD and DL-LT in the amounts shown in [Table 1] and [Table 2] were used.
D, GLD, CL, stannous octoate as a catalyst, and lauryl alcohol (Preparation Examples 1 and 2) as a molecular weight modifier were charged, and the vessel was degassed under reduced pressure and dried overnight. The reaction vessel was sealed under reduced pressure, heated to the temperatures shown in [Table 1] and [Table 2], and polymerized for a predetermined time. After completion of the reaction, the contents of the reaction vessel were dissolved in 20 volumes of chloroform, and the solution was poured into 5 volumes of hexane. The precipitated polymer was recovered and dried to obtain lactic acid-based polymers P-1 to P-9. The molecular weight of the obtained lactic acid-based polymer was determined by gel permeation chromatography using chloroform as a solvent (hereinafter referred to as G
It was measured using a (PC) and calculated in terms of polystyrene. The polymerization conditions and the molecular weight measurement results of the various lactic acid-based polymers obtained are shown in [Table 1] and [Table 2].

[0070]

[Table 1]

[0071]

[Table 2]

Preparation Examples 10 to 13 <Preparation of lactic acid polymer by direct dehydration polycondensation> Dea
In a reactor equipped with n Stark Trap, commercially available 90% L-lactic acid (hereinafter referred to as LA), 90% D-lactic acid (hereinafter referred to as DA), glycolic acid (hereinafter referred to as GA) in an amount shown in [Table 3] was used. Each) and hydroxycaproic acid (hereinafter referred to as HCA) are charged at 150 ° C.,
After distilling water while stirring at 50 mmHg for 3 hours,
Tin powder 6.2 g was added, and the mixture was stirred at 150 ° C. and 30 mmHg for 2 hours for oligomerization. To this oligomer, 28.8 g of tin powder and 21.1 kg of diphenyl ether were added, and an azeotropic dehydration reaction was carried out at 150 ° C. and 35 mmHg. The distilled water and the solvent were separated by a water separator, and only the solvent was returned to the reactor. . After 2 hours, the organic solvent returned to the reactor was 4.6
After passing through a column packed with 3 kg of molecular sieve 3A and returning to the reactor, 150 ° C., 35 mmHg
The reaction was carried out for 40 hours to obtain a polylactic acid solution. After adding 44 kg of dehydrated diphenyl ether to this solution to dilute it, the solution was cooled to 40 ° C., and the precipitated crystals were filtered to obtain 10
Wash 3 times with kg of n-hexane, 60 ° C., 50 mmH
dried at g. 0.5N-HCl 12.0k to this powder
g and 12.0 kg of ethanol were added, and the mixture was stirred at 35 ° C. for 1 hour, filtered, dried at 60 ° C. and 50 mmHg, and the lactic acid-based polymer powders P-10 to P-13 with a yield of about 85%.
Got The obtained P-10 to P-13 were dissolved in chloroform, and the molecular weight in terms of polystyrene was measured by GPC. Similarly, P-10 was dissolved in acetonitrile and measured by HLC (High Performance Liquid Chromatography) to find that the content of residual monomer in the polymer was 0.2.
% By weight. [Table 3] shows the polymerization conditions and the molecular weight measurement results of the various lactic acid-based polymers obtained.

[0073]

[Table 3]

Preparation Example 14 <Preparation of plasticizer> L-lactide 1.8 k placed in a reactor
1.0 kg of lactic acid aqueous solution (concentration 87% by weight) was added to g,
Heated at 100 ° C. for 2 hours. When cooled, a viscous transparent liquid was obtained at room temperature. The oligomer was dissolved in chloroform and the degree of polymerization distribution was measured by gel permeation chromatography. As a result, lactic acid and a lactic acid oligomer were contained. Average degree of polymerization is 2.8
Met. Hereinafter referred to as LA oligomer.

Reference Examples 1 to 7 and Reference Comparative Examples 1 to 10 P-1, P-4 and P-5 obtained in Preparation Examples were each dissolved in chloroform (concentration 10% by weight) and added thereto [Table 4]. ], [Table 7] or [Table 8]
(2'-hydroxy-5'-methylphenyl) benzotriazole (hereinafter referred to as TP), 2-hydroxy-4
-N-Octoxybenzophenone (hereinafter referred to as HOB) or 4-dodecyloxy-2-hydroxybenzophenone (hereinafter referred to as DHB) was added and mixed well. This solution was cast on a glass surface, air-dried, and then the solvent was completely removed by vacuum drying to obtain a transparent film having a thickness of 100 μm. In addition, P-2 and P obtained in Preparation Example
-3 was melted at 220 ° C. using a Brabender type kneader, and a predetermined amount of bis (2,2,6,6-tetramethyl-4-piperidyl) shown in [Table 5] or [Table 6] was obtained. Sebacate (hereinafter referred to as HAL), TP or 2-
(2'-Hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole (hereinafter referred to as T320) was added and mixed. The obtained polymer composition was heated to 50 kg / cm ^{2 at the} temperature shown in [Table 5] or [Table 6].
A transparent sheet having a thickness of 0.5 mm was prepared by hot pressing at a pressure of. In Reference Examples 1 to 3 and Reference Comparative Example 1, the film was fixed and left in a place exposed to the sun on the day (hereinafter, this condition is simply referred to as the outdoors). In Reference Comparative Example 2, although it was also outdoors, it was placed in a box (so as to allow rain to enter) so as not to be exposed to the sun (hereinafter, this condition is simply referred to as a dark place). On 24th and 44th days, a part of the film was taken and the molecular weight was measured by GPC. T
Polymer compositions containing TP (Reference Examples 1 to 3), as compared to those left outdoors without adding P (Reference Comparative Example 1)
Clearly showed that the decomposition was suppressed, and in particular, in Reference Examples 2 and 3, the decomposition behavior was almost the same as the decomposition in the dark (Reference Comparative Example 2). The obtained results are shown in [Table 4].

[0076]

[Table 4]

Reference Example 1 in Reference Example 4 and Reference Comparative Example 3
In the same manner as in Reference Comparative Example 2, the sheet was left outdoors in the same manner as in Reference Comparative Example 4 and subjected to a tensile strength test on the sheet after a predetermined number of days. The obtained results are shown in [Table 5].

[0078]

[Table 5]

In Reference Example 5 and Reference Comparative Example 5, each sheet was left outdoors, and in Reference Comparative Example 6, the sheet was allowed to stand in the dark and a tensile strength test was conducted after a predetermined number of days. The obtained results are shown in [Table 6].

[0080]

[Table 6]

In Reference Example 6 and Reference Comparative Example 7, the film was left outdoors. In Reference Comparative Example 8, the sample was left in the dark.
After 3 months, a part of the film was taken and the molecular weight was measured by GPC. The obtained results are shown in [Table 7].

[0082]

[Table 7]

In Reference Example 7 and Reference Comparative Example 9, the film was left outdoors. In Reference Comparative Example 10, it was left in the dark. After 2 months, a part of the film was taken and the molecular weight was measured by GPC. The obtained results are shown in [Table 8].

[0084]

[Table 8]

Reference Examples 8 to 11 The UV absorbers shown in [Table 9] were added to P-10 to P-13 obtained in Preparation Examples, and the mixture was mixed at room temperature with a Henschel mixer to contain the UV absorber. A lactic acid-based resin composition was obtained. Then, triacetin as a plasticizer was added to the lactic acid-based resin composition obtained from P-10 and P-11 in an amount shown in [Table 9], and the mixture was mixed with a Henschel mixer to give 18
The mixture was mixed at 0 ° C. to obtain a lactic acid resin composition containing an ultraviolet absorber and a plasticizer. The obtained lactic acid-based resin composition was pelletized using a twin-screw extruder and then melt-extruded using a single-screw extruder to obtain a film having a thickness of 150 μm. The degradability of the obtained film was evaluated in the same manner as in Reference Example 7. However, the standing period in Reference Examples 10 to 11 was one month. Table 9 shows the compounding formulation, the extrusion temperature and the change in the molecular weight.

[0086]

[Table 9]

Preparation Examples 15 to 19 <Preparation of lactic acid-based polymer film> To the lactic acid-based polymers P-5 to P-9 obtained in Preparation Example, the ultraviolet absorber shown in [Table 10] was added, and a Henschel mixer was used. And mixed at room temperature to obtain a lactic acid-based polymer composition containing an ultraviolet absorber. Then, triacetin was added to the composition obtained from P-7 and P-8, and the LA oligomer obtained in Preparation Example 6 was added to the composition obtained from P-9 as a plasticizer in [Table 10]. After adding at the ratios shown, P-7 and P
-8 was 150 ° C, and P-9 was 130 ° C and mixed using a plastomill. In addition, P-6 is 210 ℃, P
-7 and P-8 are 150 ° C, P-9 is 130 ° C, P-
Sample No. 5 was pressed at a pressure of 50 kg / cm ² at 100 ° C. to be processed into a sheet having a thickness of 1 mm. Next, these sheet materials were cooled with liquid nitrogen and pulverized with a hammer mill pulverizer to obtain a lactic acid-based polymer composition. Then, it was extruded from a T-die at a temperature shown in [Table 10] with a single screw extruder to obtain lactic acid-based polymer films F-1 to F-5 having a thickness of 110 to 120 µm. The compounding recipe, the extrusion temperature and the film thickness are shown in [Table 10].

[0088]

[Table 10]

Examples 1 to 5 <Production of degradable pressure-sensitive adhesive film> The lactic acid polymer films F-1 to F-5 obtained in Preparation Examples 15 to 19 were used as the base film of the degradable pressure-sensitive adhesive film. On the other hand, 91 parts by weight of butyl acrylate, 4 parts by weight of acrylonitrile,
An acrylic adhesive emulsion (gel content 87% by weight) obtained by emulsion polymerization of 2 parts by weight of methacrylic acid and 3 parts by weight of N-methylolmethacrylamide in an aqueous medium was added to 100 parts by weight of its solid content. A pressure-sensitive adhesive emulsion formulation containing 0.5 part by weight of trimethylolpropane polyglycidyl ether was heated at 60 ° C. for 24 hours. The pressure-sensitive adhesive emulsion formulation was applied to one surface of each of the base films F-1 to F-5 using a reverse roll coater so that the thickness after drying was 15 μm, and dried to form a pressure-sensitive adhesive layer. The drying conditions at this time were a drying temperature of 70 ° C. and a drying time of 30 minutes. The pressure-sensitive adhesive was uniformly applied to the entire surface of the substrate film, and the coatability was good. The pressure-sensitive adhesive layer was placed inside and wound around a paper tube in a roll shape while sandwiching the release paper to obtain degradable pressure-sensitive adhesive films HF-1 to HF-5. The performance evaluation results are shown in [Table 11]. The adhesive strength of the degradable pressure-sensitive adhesive films obtained in Examples 1 to 5 was evaluated by the following method.

<Adhesive strength> The adhesive film was laminated on a mirror surface stainless steel (# 800 polishing) with a laminator (pressure 1 kg / c).
m ² ), they were bonded together, left at 23 ° C. for 1 day, and then the stress when peeled off at a peeling angle of 180 ° and a speed of 300 mm / min was measured and converted into a film width of 25 mm. In addition, the adhesive film used for the evaluation of adhesive strength is 20c in soil.
It was buried in the depth of m for 12 months and taken out, and the molecular weight retention was evaluated by the following method. The obtained results are shown in [Table 11].

<Molecular weight retention> The substrate film portion of the adhesive film left in soil for 12 months after use was dissolved in chloroform, and the molecular weight in terms of polystyrene was measured by gel permeation method (GPC method). The difference from the molecular weight of is calculated and calculated by the following formula. DW = 100 W ₁ / W _{0 In the} above formula, DW: molecular weight retention W ₀ : molecular weight immediately before production W ₁ : molecular weight after leaving in soil for 12 months after use Furthermore, the adhesiveness obtained in Example 2 The tensile breaking strength of the film HF-2 was measured using a tensile tester at a tensile speed of 50 cm /
It was measured at min. As a result, the tensile strength at break was 4.6.
It was kgf / mm ² . Also, the adhesive film HF-2
To a mirror-finished stainless steel (# 800 polished) with a laminator (pressure 1 kg / cm ² ), and at 21 ° C. for 21 minutes.
Left for days. When the film was peeled off from the mirror-finished stainless steel plate in the same manner as in the above-mentioned adhesive strength evaluation method, it could be peeled off well. The peel strength at that time was 118 g / 25 mm. The tensile strength at break of the adhesive film HF-2 after peeling was 2.4 kgf / mm ² , which was sufficiently higher than the minimum tensile strength at which the adhesive film HF-2 could be favorably peeled from the stainless steel plate at the time of peeling the film.

Comparative Example 1 100 parts by weight of polyvinyl chloride (average degree of polymerization 1100),
Resin composition containing 35 parts by weight of dioctyl phthalate, 2 parts by weight of composite stabilizer, 1.0 part by weight of TP as an ultraviolet absorber and 1 part by weight of composite fatty acid amide (stearic acid: palmitic acid amide, 7: 3 weight ratio). Was kneaded and rolled by a calendar method to obtain a soft vinyl chloride film having a thickness of 100 μm. An adhesive film HF-11 was obtained in the same manner as in Example 1 except that the soft vinyl chloride film was used as the substrate film. Obtained adhesive film H
The performance evaluation of F-11 was carried out in the same manner as in Example 1, and the results are shown in [Table 11]. Also, after leaving it in soil for 12 months, it was dissolved in tetrahydrofuran and the molecular weight retention was evaluated by GPC in the same manner as in Example 1. The obtained results are shown in [Table 11].

[0093]

[Table 11]

Example 6 The lactic acid-based polymer film F-3 obtained in Preparation Example 17 was used as a base film for a degradable adhesive film. On the other hand, 23 parts by weight of methyl methacrylate, acrylic acid-2-
73 parts by weight of ethylhexyl, glycidyl methacrylate 2
A monomer mixture containing 1 part by weight and 2 parts by weight of methacrylic acid was emulsion-polymerized in an aqueous medium to obtain an acrylic resin water emulsion type adhesive having a solid content of about 47% by weight. 10 parts by weight of diethylene glycol monobutyl ether, 0.5 parts by weight of polyoxyethylene nonylphenyl ether as a surfactant, 0.5 parts by weight of trimethylolpropane polyglycidyl ether as a cross-linking agent, and 100 parts by weight of the solid content of the adhesive. Tetramethylol-tri-β-aziridinyl propionate (0.5 parts by weight) was added to each to prepare a pressure-sensitive adhesive compounding solution. Using a roll coater, one side of the base film is coated with the compounded solution, and
It was dried at 0 ° C. to obtain a degradable pressure-sensitive adhesive film HF-6 having a pressure-sensitive adhesive layer having a thickness of 10 μm. The pressure-sensitive adhesive was uniformly applied to the entire surface of the substrate film, and the coatability was good. The obtained degradable adhesive film HF-6 was used as a semiconductor silicon wafer (diameter: 6 inches, thickness: 6) in which an integrated circuit was incorporated.
00 μm) and the back surface of the semiconductor silicon wafer is polished using a polishing machine (manufactured by Disco, rotary surface grinder DFG-83H / 6 type), wafer feed rate: 200 mm / min, grindstone grain size: first; 40
/ 60 μm, second; 20/30 μm, cooling water: 5 liters / min, polishing amount: 400 μm (600 μm → 200
(μm). Then, the film was peeled off and the wafer was washed with pure water. The same operation as above was repeated to polish the back surface of 100 semiconductor silicon wafers. At this time, the number of damaged semiconductor silicon wafers was zero (0), and the working time required for polishing was about 1 hour, and the workability was good. The adhesive force of the obtained adhesive film HF-6 to the silicon mirror wafer was evaluated by the following method. The molecular weight retention was evaluated in the same manner as in Example 1. The obtained results are shown in [Table 12].
Shown in.

<Adhesive strength> Using a rubber roller having a pressing force of 2 kg / cm ² , a width of 25 mm was formed on the surface of the silicon mirror wafer.
mm sample film is attached, temperature 23 ° C, relative humidity 5
When the sample film is peeled from the surface of the silicon mirror wafer at a temperature of 23 ° C., a peeling angle of 180 °, and a peeling speed of 30 cm / min after being left in a 0% atmosphere for a predetermined time. Measure the adhesive strength of. After the evaluation of the adhesive strength, the adhesive film was
After left in soil for a month, the molecular weight retention was evaluated in the same manner as in Example 1, and the obtained results are shown in [Table 12].

Comparative Example 2 A thickness of 110 μm comprising two layers of an ethylene-vinyl acetate copolymer film (hereinafter referred to as EVA film) formed by T-die extrusion method and a polypropylene film.
Example 6 except that the EVA film layer surface was subjected to corona discharge treatment to form a base film using the laminated film of
Adhesive film HF-12 was obtained in the same manner as. The adhesive strength of the obtained adhesive film HF-12 to the silicon mirror wafer was evaluated in the same manner as in Example 6, and the results are shown in [Table 12]. Also, the molecular weight retention was evaluated in the same manner as in Example 6, and the obtained results are shown in [Table 12].

[0097]

[Table 12]

Example 7 The decomposable pressure-sensitive adhesive film HF-2 obtained in Example 2 was attached to the entire roof portion of an automobile body (new car with surface coating). After the vehicle body was left outdoors for one month, the HF-2 attached to the vehicle body was peeled off from the end, and the coating of the vehicle body could be easily peeled off without shifting to the adhesive film side. In addition, on the surface of the peeled vehicle body, there was no residual adhesive, there was no abnormality in gloss, etc., and the state of the coating film was good.

Examples 8 to 11 A degradable adhesive film was obtained by providing an adhesive layer in the same manner as in Example 1 except that the lactic acid polymer film obtained in Reference Examples 8 to 11 was used as the substrate film. It was In addition, the applicability of the pressure-sensitive adhesive to the base film was good.
Each of the obtained degradable pressure-sensitive adhesive films was attached to a mirror-finished stainless steel plate and left at 23 ° C. for 1 week. After that, when the degradable adhesive film was peeled off from the mirror-finished stainless steel plate, it could be peeled off well. The degradable adhesive film after peeling was buried in soil and left for 12 months. After that, when taken out from the soil, all the films were remarkably decomposed.

Examples 12 to 16 Lactic acid-based polymer film F obtained in Preparation Examples 15 to 19
Printing was performed on one surface of each of -1 to F-5 by using an offset printing machine (manufactured by Akira Seisakusho, type: RI-1 type). The ink is manufactured by Toka Color Chemical Co., Ltd., product name: BEST-ONE
Process black H (tack value 15.3 at 30 ° C.) was used. The sample was left to stand in a room with a relative humidity of 40% for 3 days and naturally dried at room temperature. The printing condition was good, and the transfer ink amount estimated from the transmission density was 1.3 to 2.9 g /
It was about m ² , which was about the same as the transferred amount of the transparent film for photolithography (Mylar base). On the other hand, 91 parts by weight of butyl acrylate, 4 parts by weight of acrylonitrile, 2 parts by weight of methacrylic acid, and 3 parts by weight of N-methylolmethacrylamide were emulsion-polymerized in an aqueous medium to obtain an acrylic adhesive emulsion (gel content: 87 parts by weight). %), 2 parts by weight of trimethylolpropane polyglycidyl ether was added to 100 parts by weight of the solid content, and the mixture was heated at 60 ° C. for 24 hours. One side of the printed film (the side opposite the printed side)
A pressure-sensitive adhesive emulsion formulation was applied using a reverse roll coater so that the thickness after drying was 15 μm, and dried to form a pressure-sensitive adhesive layer, and the degradable pressure-sensitive adhesive film for display PF-
1 to PF-5 were obtained. The drying condition at this time is a drying temperature of 70.
C., the drying time was 30 minutes. Further, the pressure-sensitive adhesive was uniformly applied to the entire surface of the substrate film, and the coatability was good.
The pressure-sensitive adhesive layer of PF-1 to PF-5 was placed inside, and the release paper was sandwiched and wound around a paper tube in a roll shape. In addition, PF-1
The amount of transferred ink of PF-5 to PF-5 was evaluated by the following method, and the retention of molecular weight was evaluated in the same manner as in Example 1. The evaluation results are shown in [Table 13].

<Transfer Ink Amount> Transmission Density Meter (Macbeth T
D903) was used to measure the transmission density of the printing film, and it was estimated by comparison with the transmission density of a known film.

Comparative Example 3 100 parts by weight of polyvinyl chloride (average degree of polymerization 1100),
Resin composition containing 35 parts by weight of dioctyl phthalate, 2 parts by weight of composite stabilizer, 0.05 part by weight of TP as an ultraviolet absorber and 1 part by weight of composite fatty acid amide (stearic acid: palmitic acid amide, 7: 3 weight ratio). Was kneaded and rolled by a calendar method to obtain a soft vinyl chloride film having a thickness of 110 μm. Printing and pressure-sensitive adhesive application were carried out in the same manner as in Example 12 except that the soft vinyl chloride film was used as the substrate film to obtain a degradable pressure-sensitive adhesive film PF-R for display. Performance evaluation of the obtained PF-R was carried out in the same manner as in Example 12, and the results are shown in [Table 13]. Further, after leaving it in the soil for 12 months, it was dissolved in tetrahydrofuran and the molecular weight retention was evaluated by GPC in the same manner as in Example 12, and the obtained results are shown in [Table 13].

[0103]

[Table 13]

Examples 17 to 20 Offset printing was performed in the same manner as in Example 12 except that the lactic acid-based polymer films obtained in Reference Examples 8 to 11 were used as the substrate film, and then an adhesive layer was provided to display. A degradable adhesive film for use was obtained. The pressure-sensitive adhesive was uniformly applied to the entire surface of the substrate film, and the coatability was good. The transfer ink amount of each of the obtained degradable pressure-sensitive adhesive films for display was evaluated in the same manner as in Example 12, and the result was in the range of 1.6 to 2.8 g / m ² .

Examples 21 to 22 The lactic acid-based polymer films F-1 and F-2 obtained in Preparation Examples 15 and 16 were provided on one side with a gravure rotary press (intaglio,
Gravure printing was performed using a solid plate (35 μm) for coat using a baby machine. A two-pack type ink for polyethylene terephthalate (PET) was used for the ink of Example 21, and a one-pack type ink for polystyrene was used for the ink of Example 22. After printing, the printing surface was dried with a household hair dryer. As a result of evaluating the printability and the adhesion of the ink by the following methods, all were good.
The obtained results are shown in [Table 14]. The adhesive emulsion composition was applied to one surface (opposite side of the printed surface) of the printed film so as to have a dried thickness of 15 μm and dried in the same manner as in Example 12 to form an adhesive layer, and then decomposed for display. -Type adhesive films PF-6 to PF-7 were obtained. Obtained PF-
The adhesive strengths of 6 to PF-7 and the molecular weight retention after being left for 12 months were evaluated in the same manner as in Example 12, and the results are shown in [Table 14].

<Printability> A sample film after printing is visually inspected, and printing ink is evenly distributed, and no swimming of ink, streaks, band-like unevenness, etc. are recognized as good.

<Ink adhesion> At the room temperature, cellophane tape (manufactured by Nichiban Co., Ltd., trade name: Nichiban, width: 25 m) was applied to the printed surface of the printed sample film after drying.
After m) is pressed and attached with a fingertip, it is immediately peeled off, and the ink which is not peeled off by the cellophane tape is considered good.

[0108]

[Table 14]

[0109]

The decomposable pressure-sensitive adhesive film of the present invention is characterized by using a film obtained by molding a lactic acid-based polymer as a base film and has a property of decomposing in a natural environment. Therefore, when it is discarded after use, it does not decompose in the natural environment and does not accumulate as waste. Moreover,
The degradable pressure-sensitive adhesive film of the present invention uses a lactic acid-based polymer film having an active group in the chain as a substrate film, and therefore is excellent in pressure-sensitive adhesive coating property, ink printability, paint coating property, and the like. Therefore, the adhesion between the base film and the pressure-sensitive adhesive is good, and in the production of the degradable pressure-sensitive adhesive film, it is not necessary to apply corona discharge treatment or the like to the surface of the base film to facilitate coating or coating. The process can be simplified.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Funae 2-1, Tango Dori, Minami-ku, Nagoya, Aichi Prefecture Mitsui Toatsu Chemical Co., Ltd.

Claims (12)

[Claims] 1. A degradable pressure-sensitive adhesive film comprising a base film made of a lactic acid-based polymer and a pressure-sensitive adhesive layer provided on one surface of the base film. 2. The degradable pressure-sensitive adhesive film according to claim 1, wherein the lactic acid-based polymer is at least one polymer selected from polylactic acid and lactic acid-hydroxycarboxylic acid copolymer. 3. The lactic acid-based polymer has a molecular weight of 30,000.
It is -500,000, The degradable adhesive film of Claim 1 or 2 characterized by the above-mentioned. 4. Polylactic acid is an L-lactic acid unit of 50 to 100.
Poly (L-lactic acid) having a mol%, poly (DL-lactic acid),
The degradable pressure-sensitive adhesive film according to claim 2, which is at least one polymer selected from poly (D-lactic acid) and poly (DL-lactic acid) having D-lactic acid units of 50 to 100 mol%. . 5. A lactic acid-hydroxycarboxylic acid copolymer comprising 30 to 98 mol% of lactic acid units and 2 to 2 glycolic acid units.
At least one polymer selected from lactic acid-glycolic acid copolymers having 70 mol% and lactic acid-hydroxycaproic acid copolymers having 10 to 98 mol% lactic acid units and 2 to 90 mol% hydroxycaproic acid units. The degradable pressure-sensitive adhesive film according to claim 2, wherein 6. The base film is a lactic acid-based polymer 100.
The degradability according to claim 1, comprising 1 part by weight and at least 1 part by weight of at least one plasticizer selected from glycerin triacetate, lactic acid, a lactic acid oligomer having a degree of polymerization of 2 to 10 and lactide. Adhesive film. 7. The lactic acid-based polymer 100 is used as the base film.
The degradable pressure-sensitive adhesive film according to claim 1, wherein 0.001 to 5 parts by weight of at least one additive selected from an ultraviolet absorber and a light stabilizer is included with respect to parts by weight. 8. The additive is 2-hydroxy-4-n-octoxybenzophenone and 4-dodecylquin-2-one.
Benzophenones, including hydroxybenzophenone, 2
-(2'-hydroxy-5'-methylphenyl) benzotriazole and 2- (2'-hydroxy-3 ',
Benzotriazoles including 5'-di-tert-butylphenyl) benzotriazole, and bis (2,2
The degradable pressure-sensitive adhesive film according to claim 7, which is at least one additive selected from sebacates including 2,6,6-tetramethyl-4-piperidyl) sebacate. 9. The degradable pressure-sensitive adhesive film according to claim 1, wherein the degradable pressure-sensitive adhesive film is an automobile surface protection pressure-sensitive adhesive film. 10. The decomposable adhesive film according to claim 1, wherein the degradable adhesive film is a protective adhesive film for a semiconductor wafer used in back grinding and dicing of a semiconductor wafer having an integrated circuit incorporated therein. Adhesive film. 11. The degradable pressure-sensitive adhesive film is a pressure-sensitive adhesive film for surface protection of at least one processed product selected from a metal plate and a metal processed product, a synthetic resin plate and a synthetic resin processed product, and a wood board and a wood processed product. A degradable pressure-sensitive adhesive film according to claim 1. 12. The degradable pressure-sensitive adhesive film according to claim 1, wherein the degradable pressure-sensitive adhesive film is a display pressure-sensitive adhesive film having a substrate film having at least one surface printed or painted.