JPH027988B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a releasable treatment agent comprising a polyvinyl carbamate compound having excellent heat resistance and a method for producing the same. BACKGROUND ART The back side of a base material in an adhesive tape, an adhesive tape, etc. is usually subjected to a release treatment using a release treatment agent. The properties required for this releasable treatment agent or its treatment layer include smooth unwinding of the tape, etc. during use, no reduction in adhesive strength by transferring to the adhesive surface, and excellent adhesion to the base material. In addition to not falling off easily, it has excellent heat resistance and has little change in peeling properties over time due to heat. Conventionally, as a stripping agent made of a reaction product of polyvinyl alcohol and an isocyanate compound, polyvinyl alcohol is dispersed in a solution in which polyvinyl alcohol is insoluble, such as xylene or toluene, and octadecyl isocyanate is added to the solution and reacted. (Special Publication No. 29-7333, Publication No. 3382-1982). These releasable processing agents were developed to overcome the problems caused by the superior releasability of conventional silicone-based compounds, such as the problem of tape rolls becoming loose and the problem of not being able to overlay them. It is something. Problems to be Solved by the Invention However, in the case of conventional stripping agents made of reaction products of polyvinyl alcohol and isocyanate compounds, the reaction is carried out by dispersing polyvinyl alcohol in an insoluble solvent. Based on this, there were problems in synthesis, such as the impossibility of using polyvinyl alcohol with a degree of saponification of 95 mol % or more, and the extremely slow reaction rate of polyvinyl alcohol with an average degree of polymerization of 2000 or more. In addition, there was also the problem that the release properties of the release treatment agent or its treated layer changed significantly depending on the thermal history, resulting in poor heat resistance. Means for Solving the Problems The present inventors have conducted intensive research to overcome the above problems and develop a polyvinyl carbamate-based peeling agent with excellent heat resistance and a method for producing the same. The inventors have also discovered that the object can be achieved by reacting polyvinyl alcohol and an isocyanate compound in a solution state, leading to the present invention. That is, the present invention relates to (A) general formula () (However, R is a hydrocarbon group having 8 or more carbon atoms or a halogen-substituted hydrocarbon group.) Has a structural unit represented by in the molecule, the content of vinyl alcohol units is less than 5 mol%, and (A) and (B) that the main component is a polyvinyl carbamate compound with a content of organic acid vinyl ester units of 5 mol% or less, and (B) that it has excellent heat resistance.
A stripping treatment agent having the characteristics of, polyvinyl alcohol with a degree of saponification of 95 mol% or more, and an amount of the general formula () RNCO ... () in an amount exceeding 0.95 equivalent to the hydroxyl group in this polyvinyl alcohol A hydrocarbon group having a number of 8 or more or a halogen-substituted hydrocarbon group) is reacted with an isocyanate compound represented by the following in a solution state in a solvent from the start of the reaction to the end of the reaction, including its intermediate products. The present invention provides a method for producing a releasable treatment agent characterized by the following. The stripping treatment agent of the present invention comprises a polyvinyl carbamate compound as a reaction product of polyvinyl alcohol and an isocyanate compound. Its manufacture can be carried out, for example, as follows. That is, first, a predetermined amount of polyvinyl alcohol is dissolved in a water-soluble solvent such as dimethyl sulfoxide, and a predetermined amount of an isocyanate compound is added to the resulting solution and reacted under heating. that time,
If necessary, it is necessary to maintain the reaction system in a solution state by adding a solvent such as xylene or toluene to dissolve the intermediate product. As described above, the object of the present invention is achieved by constantly maintaining the reaction system in a solution state from the start of the reaction to the end of the reaction. Therefore, the object of the present invention cannot be achieved by the conventional method of starting the reaction while dispersing polyvinyl alcohol in a solvent such as xylene or toluene. The end point of the reaction is determined by the disappearance of isocyanate groups from the reaction system. In carrying out the above reaction, a catalyst typified by, for example, an organic tin compound may be used, if necessary, to promote the reaction between the hydroxyl group and the isocyanate group. The polyvinyl alcohol used in the present invention is suitably one having an average degree of polymerization of 100 to 5,000. If the average degree of polymerization is less than 100, the peeling agent obtained will have poor film strength and heat resistance, while if it exceeds 5000, the solubility will be poor and this is not preferred in terms of reaction work. Polyvinyl alcohol, which exhibits the advantages of the dissolution method of the present invention, has an average degree of polymerization of 500.
Of these, the number is between 2000 and 3000. Further, the advantage of the present invention as a dissolution method is exhibited when the degree of saponification of polyvinyl alcohol is 95 mol % or more. General formula () used in the present invention:
Isocyanate compounds represented by RNCO include, for example, linear or branched alkyl groups, alkenyl groups, alkadienyl groups, alkapolyenyl groups, alkynyl groups having 8 or more carbon atoms, especially 8 to 32 carbon atoms, or halogens thereof. Examples include isocyanates having compounds. Specifically, octyl isocyanate, nonyl isocyanate, decyl isocyanate, undecyl isocyanate, dodecyl isocyanate, tridecyl isocyanate, tetradecyl isocyanate, pentadecyl isocyanate, hexadecyl isocyanate, heptadecyl isocyanate, octadecyl isocyanate, nonadecyl isocyanate, eicosyl isocyanate. , heneicosyl isocyanate, docosyl isocyanate, tricosyl isocyanate, tetracosyl isocyanate, pentacosyl isocyanate, hexacosyl isocyanate, octacosyl isocyanate, nonacosyl isocyanate, toiacontyl isocyanate, hentriacontyl isocyanate, dotria Representative examples include contyl isocyanate, 4-methyl-10-ethyl-2-dodecenyl isocyanate, octadecenyl isocyanate, decynyl isocyanate, polychlorohexadecyl isocyanate, and perfluorohexadecyl isocyanate. can. Examples of the solvent used to dissolve polyvinyl alcohol in the present invention include dimethyl sulfoxide, N-methylpyrrolidone, triethyl phosphate, diethylene glycol dimethyl ether, acetylacetone, sulfolane, butyrolactone, dioxane, tetrahydrofuran,
Examples include water-soluble ones such as methyl lactate. There is no particular limitation on the amount of the solvent to be used, and an amount that can dissolve the entire amount of polyvinyl alcohol used is used. In general,
3 to 8 times the weight of polyvinyl alcohol is used. Note that oil-soluble solvents such as toluene and xylene are suitable as the solvent for dissolving the intermediate product. On the other hand, isocyanate compounds are used in amounts exceeding 0.95 equivalents based on polyvinyl alcohol hydroxyl groups, usually
0.95 to 1.1 equivalents are used. As a result, a target product having a content of vinyl alcohol units of less than 5 mol % is obtained. In this way, the general formula () (However, R is a hydrocarbon group having 8 or more carbon atoms or a halogen-substituted hydrocarbon group as described above.) can get. The average degree of polymerization of the polyvinyl carbamate compound is determined by the polyvinyl alcohol used. Further, the content of organic acid vinyl ester units, such as vinyl acetate units, in the polyvinyl carbamate-based compound is determined by the degree of saponification of the polyvinyl alcohol used, but in the present invention, the content of the ester units is 5 mol% or less. It is preferable from the viewpoint of heat resistance. Effects of the Invention According to the present invention, since the reaction is allowed to proceed in a solution state from the start to the end, the reaction can be easily carried out even when using polyvinyl alcohol with a high degree of saponification and a high degree of polymerization. can. Furthermore, the obtained releasable treatment agent has excellent heat resistance and excellent adhesive strength or adhesion to the substrate. Examples Example 1 20 parts (parts by weight, the same shall apply hereinafter) of polyvinyl alcohol with an average degree of polymerization of 2600 and a degree of saponification of 99 mol% were placed in a 500 c.c. four-necked container equipped with a reflux condenser and a moisture metering receiver. Add dimethyl sulfoxide to the flask.
Add 130 parts and dissolve the polyvinyl alcohol while stirring. Thereafter, 70 parts of xylene was added to this solution, heated while stirring, and dissolved by heating at 140° C. for 2 hours, and the water in the polyvinyl alcohol was removed. Next, after cooling the system to 100°C, 147 parts of octadecyl isocyanate is added and reacted. The system was constantly maintained in a homogeneous state by adding xylene at appropriate times as the reaction progressed, and the reaction was allowed to proceed at 120°C for 5 hours.
The end point of the reaction is defined as the point at which no isocyanate groups remain in the system. The obtained reaction product is precipitated in methanol, separated and purified to obtain the desired product. Next, a 1% by weight toluene solution of the purified product is applied onto a cellophane film (thickness: 50 μm) at a coating amount (solid content) of 0.05/m ² and dried to obtain a release-treated film. Attach cellophane adhesive tape (No. 29, manufactured by Nitto Electric Industry Co., Ltd.) to this treated surface and
The peeling force (180 degree peel) was measured after heating at 70℃ for 24 hours and then standing at 20℃ for 4 hours.
300mm/min). The results are shown in the table. Comparative Example 1 A reaction with 147 parts of octadecyl isocyanate was attempted by dispersing 20 parts of the polyvinyl alcohol of Example 1 in 80 parts of xylene, but the reaction did not substantially proceed and no product could be obtained. Example 2 A target product was obtained according to Example 1 except that 128 parts of octadecyl isocyanate was used, and the peeling force of the purified product on the treated surface was measured. The results are shown in the table. Example 3 The desired product was obtained in accordance with Example 1, except that 20 parts of polyvinyl alcohol with an average degree of polymerization of 500 and a degree of saponification of 99 mol%, 110 parts of dimethyl sulfoxide, and 133 parts of octadecyl isocyanate were used. The peel force of the treated surface was measured. The results are shown in the table. Comparative Example 2 A reaction similar to that of Comparative Example 1 was attempted by dispersing the polyvinyl alcohol of Example 3 in xylene, but no product could be obtained. Example 4 A target product was obtained according to Example 1, except that 20 parts of polyvinyl alcohol with an average degree of polymerization of 1500 and a degree of saponification of 95 mol%, 120 parts of dimethyl sulfoxide, and 123 parts of octadecyl isocyanate were used, and the target product was treated with the purified product. The peel force of the surface was measured. The results are shown in the table. Comparative Example 3 A reaction similar to that of Comparative Example 1 was attempted by dispersing the polyvinyl alcohol of Example 4 in xylene, but no product could be obtained. Comparative Example 4 20 parts of polyvinyl alcohol with an average degree of polymerization of 1400 and a degree of saponification of 88 mol% was dispersed in 204 parts of xylene,
The desired product was obtained in accordance with Example 1, except that 116 parts of octadecyl isocyanate was added to this dispersion and reacted, and the peeling force of the purified product on the treated surface was measured. The results are shown in the table.

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Claims (1)

[Scope of Claims] 1. A removable treatment agent having the following characteristics (A) and (B). (A) General formula () (However, R is a hydrocarbon group having 8 or more carbon atoms or a halogen-substituted hydrocarbon group.) Has a structural unit represented by in the molecule, the content of vinyl alcohol units is less than 5 mol%, and The main component shall be a polyvinyl carbamate compound having an organic acid vinyl ester unit content of 5 mol% or less. (B) Excellent heat resistance. 2. The releasable treatment agent according to claim 1, wherein the polyvinyl carbamate compound has an average degree of polymerization of 100 to 5,000. 3 Polyvinyl alcohol with a degree of saponification of 95 mol% or more and the general formula () RNCO ... () in an amount exceeding 0.95 equivalent to the hydroxyl group in this polyvinyl alcohol (However, R is a hydrocarbon group having 8 or more carbon atoms or A stripping treatment agent characterized by reacting an isocyanate compound represented by (a halogen-substituted hydrocarbon group), including its intermediate products, in a solution state in a solvent from the start of the reaction to the end of the reaction. manufacturing method. 4 Average degree of polymerization of polyvinyl alcohol is 100~
5,000.