JP3026418B2 - Release treatment agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a releasable treating agent, and more particularly, to a substrate using a pressure-sensitive adhesive such as a pressure-sensitive adhesive tape, a pressure-sensitive adhesive label, a pressure-sensitive adhesive sheet, etc. The present invention relates to a release treatment agent capable of making the back surface or the surface of release paper peelable.

[0002]

2. Description of the Related Art Conventionally, a release agent used for the above purpose is:
The silicone-based release agent is roughly classified into a silicone-based release agent and a non-silicone-based release agent. The silicone-based release agent has excellent release performance with respect to any of a rubber-based and an acrylic-based adhesive.

[0003]

However, since silicone-based release agents require heat treatment at a high temperature at the time of release agent treatment, they cannot be used for substrates having poor heat resistance, such as OPP and polyethylene. There is a problem with the low molecular silicone compound present as an impurity in the release agent, and there are drawbacks in writing properties and the like. On the other hand, examples of non-silicone release agents include long-chain acrylate polymers, fluorinated alkyl vinyl monomer polymers, polyvinyl alcohol, and polycarbamates. These release agents are satisfactory in terms of releasability and residual adhesiveness. It cannot be done.

[0004] Japanese Patent Publication No. 29-2989 describes a release treatment agent comprising a reaction product obtained by reacting polyvinyl alcohol with stearyl isocyanate. This polyvinyl alcohol-based release agent has the most effective non-silicone release agent because it exhibits a release effect with an extremely small amount of coating, has excellent performance at high speed release, and has good writing and heat resistance. It is used.

However, this type of release agent is poor in adhesion and flexibility and poor in solubility in a solvent, so that the solution gels in winter or the like, or the release agent precipitates or precipitates. There is a problem with workability. Accordingly, an object of the present invention is to provide a release treatment agent which is excellent in adhesion and flexibility to a base material and which is excellent in workability due to improvement in solubility.

[0006]

The above objects are achieved by the present invention described below. That is, the present invention provides a release treating agent comprising a reaction product of a polyvinyl alcohol-based copolymer to which an aliphatic polyester is grafted and an isocyanate having an aliphatic group having 12 or more carbon atoms. It is.

The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found that a polyvinyl alcohol-based copolymer having an aliphatic polyester grafted thereon has a carbon number of 12 or less.
A reaction product obtained by reacting an isocyanate having two or more aliphatic groups has excellent release performance, and also has excellent adhesiveness and flexibility to a substrate, and workability accompanying improvement in solubility. Was found to be improved, and the present invention was completed.

Further, an aliphatic group having 12 or more carbon atoms is added to a polyvinyl alcohol copolymer obtained by grafting a polyester selected from polycaprolactone or polyvalerolactone to polyvinyl alcohol having a degree of saponification of 60 mol% or more. The release treatment agent comprising a reaction product obtained by reacting the isocyanate has excellent performance.

A polyvinyl alcohol-based copolymer obtained by grafting an aliphatic polyester to polyvinyl alcohol,
The reaction product obtained by reacting an isocyanate having an aliphatic group having 12 or more carbon atoms is a reaction product obtained by reacting a conventional polyvinyl alcohol with an isocyanate having an aliphatic group having 12 or more carbon atoms. Compared to things
The adhesiveness to the substrate and the flexibility are remarkably excellent, and the solubility in a solvent is remarkably excellent.

More specifically, the present invention provides a releasable treatment agent in which polyvinyl alcohol is modified by grafting an aliphatic polyester to polyvinyl alcohol, and adhesion, flexibility and solubility are remarkably improved. Can be.

[0011]

Next, the present invention will be described in more detail with reference to preferred embodiments. The resin constituting the release treatment agent of the present invention can be obtained as follows. First, a polyvinyl alcohol copolymer is obtained by graft copolymerizing a lactone compound such as an ε-caprolactone compound or a δ-valerolactone compound as an aliphatic polyester compound with polyvinyl alcohol having a saponification degree of 60 mol% or more.

The polyvinyl alcohol used in the present invention has a saponification degree of vinyl acetate unit of 60 mol% or more and a weight average polymerization degree of 20 to 20,000, preferably 200 to 20,000.
3,000. In the present invention, the aliphatic polyester compound to be reacted with polyvinyl alcohol is ε
A lactone compound capable of forming a polyester by conventional lactone ring-opening polymerization, such as a caprolactone compound and a δ-valerolactone compound.

In the present invention, the caprolactone compound to be reacted with polyvinyl alcohol includes, for example, ε
-Caprolactone, monomethyl-ε-caprolactone,
Monoethyl-ε-caprolactone, monopropyl-ε-
Various monoalkyl-ε-caprolactones, such as caprolactone, and monododecyl-ε-caprolactone, both of the two alkyl groups are not bonded to the carbon atom at the ε-position, but are each at a similar separate carbon atom Substituted dialkyl-ε-caprolactones, the carbon atom at the ε-position of the lactone ring is not di-substituted and the other two or three
Trialkyl-ε-caprolactone in which three carbon atoms have been replaced by three alkyl groups, and ethoxy-
Alkoxy-ε-caprolactones such as ε-caprolactone or cycloalkyl- such as cyclohexyl-, phenyl- and benzyl-ε-caprolactone.
ε-caprolactone, aryl-ε-caprolactone, aralkyl-ε-caprolactone and the like.

Further, the δ-valerolactone compound includes
5-valerolactone, 3-methyl-5-valerolactone, 3,3-dimethyl-5-valerolactone, 2-methyl-5-valerolactone, 3-ethyl-5-valerolactone, and the like.

The reaction between the polyvinyl alcohol and the lactone compound is carried out by mixing the two and reacting them at a temperature of 10 to 220 ° C. for several hours to tens of hours, preferably using a suitable catalyst under a nitrogen stream. Thus, a polyvinyl alcohol copolymer obtained by grafting an aliphatic polyester to polyvinyl alcohol can be obtained. In other words,
When polyvinyl alcohol alone is reacted with isocyanate, it is generally in an emulsified and dispersed state or a state of being dissolved in a solvent such as water or alcohol. This is because, in addition to the extremely high softening temperature of polyvinyl alcohol, when heated at a temperature of 100 ° C. or more for a long time, the polyvinyl alcohol gradually undergoes thermal decomposition.

On the other hand, according to the present invention, in the reaction between polyvinyl alcohol and the lactone compound, the white powdered polyvinyl alcohol and the liquid lactone compound are in an inhomogeneous state in the initial mixed state of the two, As the reaction proceeded, the polyvinyl alcohol as a white powder changed to a uniform reaction product, and despite the high temperature, the thermal decomposition observed in the unreacted polyvinyl alcohol was not observed.

Next, by changing the molecular weight of the aliphatic polyester to be grafted onto the polyvinyl alcohol according to the present invention, that is, by changing the weight ratio between the polyvinyl alcohol and the aliphatic polyester, the polyvinyl alcohol having the characteristics of the polyvinyl alcohol and the aliphatic polyester can be obtained. An alcohol-based copolymer is obtained. The weight ratio of the polyvinyl alcohol to the aliphatic polyester is 90 to 60 parts by weight of the polyvinyl alcohol and 10 to 4 parts of the aliphatic polyester.
A range of 0 parts by weight is preferred.

The polyvinyl alcohol-based copolymer having an amount of polyvinyl alcohol exceeding 90 parts by weight and an aliphatic polyester of less than 10 parts by weight has an adhesive property in a peelable resin obtained due to performance from polyvinyl alcohol. The effect of improvement in flexibility and solubility is small. On the other hand, a polyvinyl alcohol-based copolymer in which the amount of the polyvinyl alcohol is less than 60 parts by weight and the amount of the aliphatic polyester exceeds 40 parts by weight is not suitable as the release treatment agent of the present invention because of the performance from the aliphatic polyester. .

In the present invention, in order to graft-polymerize a lactone compound to polyvinyl alcohol, the two are mixed, and preferably a catalyst is added under a nitrogen stream to form a mixture of 80 to 2 times.
The stirring is carried out at a temperature of 20 ° C. for several hours. It is also possible to carry out graft polymerization in a molten and heated state using a kneading machine such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader or a Brabender.

Next, the polyvinyl alcohol-based copolymer obtained as described above is reacted with an isocyanate having an aliphatic group having 12 or more carbon atoms to form a resin constituting the release treatment agent of the present invention. can get. The isocyanate having an aliphatic group used in the present invention can be represented by the general formula R-NCO. R in the formula is a linear aliphatic group having 12 or more carbon atoms, and includes an alkyl group and an alkenyl group.

Specific examples of the isocyanate having an aliphatic group include lauryl isocyanate (C 12), myristyl isocyanate (C 14),
Cetyl isocyanate (carbon number 16), stearyl isocyanate (carbon number 18), eicosanyl isocyanate (carbon number 20), docosanyl isocyanate (carbon number 22), tetracosanyl isocyanate (carbon number 2)
4), hexacosanyl isocyanate (26 carbon atoms),
Octacosanyl isocyanate (28 carbon atoms) and the like.

The isocyanate having an aliphatic group is
A reaction product of a linear alcohol having 12 or more carbon atoms and a diisocyanate in a molar ratio of about 1: 1 which may have one free isocyanate group;
As described above, the release treatment agent of the present invention is obtained.

Examples of the linear alcohol having 12 or more carbon atoms include lauryl alcohol (12 carbon atoms), myristyl alcohol (14 carbon atoms), cetyl alcohol (16 carbon atoms), and stearyl alcohol (1 carbon atom).
8), eicosanol (carbon number 20), docosanol (carbon number 22), tetracosanol (carbon number 24), hexacosanol (carbon number 26), octacosanol (carbon number 28) and the like. Examples of the diisocyanate to be reacted with the linear alcohol having 12 or more carbon atoms include various diisocyanates used as raw materials for polyurethane resins.

Next, the reaction of the polyvinyl alcohol-based copolymer with an isocyanate having an aliphatic group having 12 or more carbon atoms will be described. After dissolving or dispersing the copolymer in a solvent inert to isocyanate groups, isocyanate having an aliphatic group having 12 or more carbon atoms is reacted at 80 to 150 ° C.

At this time, the reaction ratio of the isocyanate is 0.6 to the hydroxyl groups in the polyvinyl alcohol-based copolymer.
A range of -1.1 equivalents is preferred. The reaction is stopped when the absorption peak based on the isocyanate group in the reaction mixture disappears. The reaction mixture was poured into a poor solvent such as 2 to 5 times of alcohol to precipitate, and the precipitate was separated by filtration.
Dry to obtain the object of the present invention. The reaction product thus obtained exhibits excellent solubility in solvents such as toluene and xylene, and has excellent properties such as releasability, residual adhesiveness, adhesion to a substrate, and flexibility. .

The release treatment agent of the present invention comprises the above reaction product, and can be applied in a solid state or a solution state. Also, when forming a peelable film with this release treatment agent,
By crosslinking the hydroxyl groups remaining in the copolymer with various crosslinking agents, a release film excellent in heat resistance, mechanical strength, water resistance, solvent resistance and the like can be obtained.
Any of various crosslinking agents can be used as long as it reacts with a hydroxyl group. Specifically, a phenol resin, a melamine resin, an epoxy resin, an isocyanate resin and the like are suitable.

The release treatment agent of the present invention has a solid content of 0.01 to 1.0 g / m ² , preferably 0.05 to 0.1 g / m ² .
5 g / m ² is applied to a support such as a plastic film, sheet, or tape to form a peelable film, sheet,
It can be used as a product such as a tape, and can be used as a product such as a pressure-sensitive adhesive, a pressure-sensitive adhesive tape, a pressure-sensitive adhesive tape or a pressure-sensitive adhesive using a rubber-based, acrylic-based, or hot-melt-based pressure-sensitive adhesive.

[0028]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the text and tables, parts and% are based on weight unless otherwise specified. Production Examples 1 to 3 Polyvinyl alcohol having a saponification degree of 98.5% (polymerization degree of 55
0), ε-caprolactone and tetrabutyl titanate were charged into a reaction vessel and stirred at 1 ° C./2 under a nitrogen stream.
Heat for ~ 3 min. At 150 to 160 ° C., the heterogeneous system up to that becomes gradually homogeneous, and at 180 to 200 ° C., it becomes completely homogeneous. The reaction was continued at 200 to 220 ° C. for 6 hours to obtain a resin constituting the release treatment agent of the present invention having the physical properties shown in Table 1 below.

Table 1

[Test Methods] The tests of the physical properties shown in Table 1 above were performed by the following methods. * 1) Molecular weight: N, N-dimethylformamide solution (5
%) GPC measurement. * 2) Hardness: A sheet obtained by press-molding the resin obtained in Production Examples 1 to 3 at a temperature of 160 ° C is JIS K-6.
It was measured with an A-type hardness meter based on No. 301.

* 3) 100% modulus (MPa), tensile strength (MPa) and elongation (%): Press molded sheets of the resin obtained in Production Examples 1 to 3 were subjected to JIS K-7311-3.
No. dumbbell was used to measure the physical properties. * 4) Vicat softening point: JIS K-
7206.

Example 1 30 parts of the resin of Production Example 1 were dispersed in 60 parts of xylene.
166 parts of stearyl isocyanate are added at the reflux temperature. As the reaction proceeds, the mixed solution becomes homogeneous and becomes completely homogeneous, and the reaction is further continued for 1 hour. After cooling, the reaction product is poured into three times the amount of methanol to obtain a white precipitate. After washing, drying and pulverizing, a desired release treatment agent was obtained.

Example 2 Using 30 parts of the resin of Production Example 2, 60 parts of xylene and 185 parts of docosanyl isocyanate, the reaction was carried out in the same manner as in Example 1 to obtain a desired release treatment agent. Example 3 A reaction was carried out in the same manner as in Example 1 using 40 parts of the resin of Production Example 3, 70 parts of xylene, and 200 parts of hexaconyl cyanocyanate to obtain the intended release treatment agent.

Comparative Example 1 Polyvinyl alcohol (degree of saponification: 98.5%, degree of polymerization: 55)
0) Using 25 parts of xylene, 50 parts of xylene and 166 parts of stearyl isocyanate, the reaction was carried out in the same manner as in Example 1 to obtain a release treating agent. Comparative Example 2 Polyvinyl Alcohol (Saponification Degree 98.5%, Degree of Polymerization 55
0) 25 parts, xylene and 200 parts of tocosanyl isocyanate were reacted in the same manner as in Example 1 to obtain a release treating agent.

Peeling Force Test The peeling treatment agents obtained in the above Examples and Comparative Examples were dissolved in a 2% concentration toluene solution and dried on a corona-treated surface of an OPP film and an untreated surface of a PET film. Coating was performed so that the amount of adhesion was 0.1 g / m ² . A 25 mm wide rubber-based adhesive tape (Nichiban) is attached to this peelable film.
And 2 kg of acrylic adhesive tape (Sekisui Chemical)
At room temperature (20 ° C, humidity 52
%) After 24 hours, after storage at a high temperature (50 ° C.) for 24 hours, and after leaving at room temperature for 2 hours.

Drop-off test A gauze was reciprocated 10 times with a load of 50 g / cm ^{2 on} the release-treated layer, and the adhesion to the support was observed. ○ ・ ・ ・ No change. △ ・ ・ ・ Some parts are missing. ×: Dropped out.

Adhesion Test 100 pieces of 1 mm square cells were cut into the coating film with a knife, and a peeling test was performed with a cellophane tape. Storage test A 2% toluene dilution was stored at 5 ° C. and 23 ° C. for 3 days, and changes in the solution were observed.

Table 2 Peeling force (g / inch)

[0039]

EFFECTS OF THE INVENTION The release treatment agent of the present invention is excellent in workability due to improvement in adhesion, flexibility and solubility to a substrate, and has excellent release performance even at room temperature and 50 ° C. It is shown.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI D21H 19/62 D21H 19/62 27/00 27/00 A (72) Inventor Katsumi Kuriyama 1-7-7 Nihonbashi Bakurocho, Chuo-ku, Tokyo No. 6 in Dainichi Seika Kogyo Co., Ltd. (56) References JP-A-7-179714 (JP, A) JP-A-7-109339 (JP, A) JP-A-58-63722 (JP, A) JP-A Sho 49-114618 (JP, A) JP-A-57-155231 (JP, A) JP-A-63-51474 (JP, A) JP-A-63-117028 (JP, A) JP-A-3-212459 (JP, A) A) JP-A-8-100024 (JP, A) JP-A-9-59588 (JP, A) JP-A-9-59326 (JP, A) JP-A-7-138897 (JP, A) (58) Survey Fields (Int.Cl. ⁷ , DB name) C09D 167/00-167/08 C09D 129/04 C09D 151/00-151/10 C09D 5/00 C09J 167/00- 167/08 C09J 129/04 C09J 151/00-151/10 C09J 5/02 C08G 63/00-63/91 C08F 261/04 D21H 19/60 D21H 19/62 D21H 27/00

Claims (3)

(57) [Claims] 1. A releasable treatment agent comprising a reaction product of a polyvinyl alcohol-based copolymer onto which an aliphatic polyester is grafted and an isocyanate having an aliphatic group having 12 or more carbon atoms. 2. The release treatment agent according to claim 1, wherein the polyvinyl alcohol has a degree of saponification of 60 mol% or more. 3. The release treating agent according to claim 1, wherein the aliphatic polyester comprises polycaprolactone or polyvalerolactone.