JPH11147916A - Method for producing polyvinyl alcohol rich in syndiotacticity - Google Patents

Abstract

(57) [Problem] To provide a method for producing PVA having high syndiotacticity even at a polymerization temperature of 0 ° C. or higher. SOLUTION: The following formula: (Wherein, R ¹ and R ² each represent a fluorinated hydrocarbon group, a part of which may be substituted with a chlorine atom;
³ is a hydrocarbon group, a fluorinated hydrocarbon group, a fluorine atom,
Or a chlorine atom) is polymerized and then saponified to produce polyvinyl alcohol having a syndiotacticity (duplex) of 65% or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The invention of this application relates to polyvinyl alcohol (hereinafter referred to as PVA) having a high syndiotacticity.
). More specifically, the invention of this application relates to a method for producing a high syndiotactic PVA having a syndiotacticity of 65% or more, comprising polymerizing a fluorine-containing branched carboxylic acid vinyl ester and then saponifying the polymer. .

[0002]

2. Description of the Related Art In general, PVA is produced by saponifying a polyvinyl ester, particularly polyvinyl acetate, obtained by polymerization of an aliphatic vinyl ester with an alkali catalyst. It is well known that the physical properties of PVA greatly change due to the stereoregularity of the side chain hydroxyl group. That is, the higher the degree of isotacticity or syndiotacticity, the higher the crystallinity of PVA, and the higher the heat resistance and strength of molded products such as fibers and films. In particular, the increase in syndiotacticity leads to an increase in intermolecular hydrogen bonds, so that the physical properties are dramatically improved.

Generally, the stereoregularity of PVA obtained from polyvinyl acetate is as low as about 53% in syndiotacticity (duplex), and its tacticity does not change much even if the polymerization solvent or polymerization temperature is changed. As a method for obtaining PVA having a high syndiotacticity, there is known a method in which vinyl trifluoroacetate having a polar substituent or vinyl pivalate having a bulky substituent is polymerized and then saponified. For example, vinyl trifluoroacetate in n-nonane
When polymerized at 40 ° C, syndiotacticity of 63% P
VA is obtained (Makromol, Chem., 165, 2
17, p. 1973). However, the monomer vinyl trifluoroacetate has a problem that it is easily decomposed even by a very small amount of water and lacks storage stability.

Recently, vinyl pivalate has been polymerized in n-hexane at -40 ° C. to give syndiotactic-6.
It is reported that 9% of PVA is obtained (Polyme
r J., Vol. 29, No. 3, p. 293, 1997).
However, according to this report, the polymerization time is indeed as long as 10 days, which is not a level that can be carried out on a very industrial scale.
Further, in order to obtain PVA having a syndiotacticity of 65% or more, polymerization at a low temperature of 0 ° C. or less is indispensable, which is disadvantageous in terms of equipment, and the productivity is low due to a slow polymerization reaction. There is a problem. In addition, the obtained polyvinyl pivalate is less likely to be saponified and is usually reacted under violent alkaline conditions. Therefore, there is a problem that the PVA is colored by impurities such as trace amounts of oxygen in the reaction system.

[0005] On the other hand, it has long been reported that PVA having a syndiotacticity of 74% can be synthesized by saponifying a polymer obtained by low-temperature cationic polymerization of tin tetrachloride with trimethylsilyl vinyl ether in nitroethane (74%). Molecular Chemistry, 24, 606, 1967
Year). However, cationic polymerization is disadvantageous in that it is easily affected by impurities such as moisture in the air, and in this case, it is industrially disadvantageous because the polymerization temperature needs to be lowered to -78 ° C. The degree of polymerization of the PVA to be produced is extremely low at 30 and the physical properties such as the strength of the molded product are inevitably inadequate.

In addition, other than the above-mentioned vinyl trifluoroacetate,
Vinyl ester having a linear fluorinated hydrocarbon group
Has been studied in the past (Vysokomol
Soedin., Ser. B, Volume 9, Issue 1, Page 4, 1967
Year, and Kinet. Mech. Polyreactions, Int. Symp. Ma
cromol. Chem., Prepr., vol. 3, p. 249, 1969.
Year). And specifically, at 20 ° C., 7H-dodecafluoro
Vinyl heptanoate, CH _Two= CH-OCO (CF_TwoCF
_Two)_ThreeSyndiotacticity by polymerizing H
It is reported that 78% of PVA is obtained. Only
However, the experimental data in this report is only this one point.
The melting point of 236 ° C. of the obtained PVA is
Because it is the same level as
I have to say that there is. Actually, at 20 ° C
When you go, the syndiotacticity is 64%,
In addition, it drops to 61% at 60 ° C.

Further, Japanese Patent Application Laid-Open No. 62-204823 discloses a fluorine-substituted vinyl pivalate, CH ₂ ＣＨCH
—OCOC (CF ₃ ) _n (CF ₃ ) _3-n (n = 1-3)
A method for producing a gas separation element having high selective permeability by homo- and copolymerization of is disclosed. However, the obtained polyvinyl ester has not been converted to PVA, and there is no description about stereoregularity.

[0008]

SUMMARY OF THE INVENTION The invention of this application has been made in view of the state of the prior art as described above, and overcomes the limitations of the prior art, and has a high quality and physical properties. It is an object of the present invention to provide a new method for producing PVA that can efficiently and stably produce PVA having a high nervousness (duplex) of 65% or more at a polymerization temperature of 0 ° C. or more.

[0009]

In order to solve the above-mentioned problems, the present application first provides a first invention as follows.

[0010]

Embedded image

Wherein R ¹ and R ² each represent a fluorinated hydrocarbon group which may be partially substituted with a chlorine atom, and R ³ represents a hydrocarbon group or a fluorinated hydrocarbon group. ,
A method for producing PVA having a syndiotacticity (duplex) of at least 65%, comprising polymerizing a fluorine-containing branched carboxylic acid vinyl ester represented by a fluorine atom or a chlorine atom) and then saponifying the polymer. I will provide a.

This application also relates to the manufacturing method.
Thus, as a second invention, R¹And R ^TwoBut each
Having 1 to 3 carbon atoms which may be partially substituted with a chlorine atom
As a third aspect of the present invention, a method for producing a fluorinated hydrocarbon,
^ThreeIs a hydrocarbon group having 1 to 3 carbon atoms, or fluorinated carbon
In a fourth aspect, the method is a hydrogen group.¹And R^Two
Are each a trifluoromethyl group and R^ThreeIs a methyl group
Or a trifluoromethyl group, or even a fifth
The invention also provides a method of polymerizing at a temperature of 0 ° C. or higher.
You.

[0013]

Embodiments of the present invention will be described below in detail. First, the fluorine-containing branched carboxylic acid vinyl ester represented by the above formula will be described. In the formula, each of R ¹ and R ² is a group in which a part or all of the hydrogen atoms bonded to the carbon atom of the hydrocarbon group is fluorine. A fluorinated hydrocarbon group substituted by an atom,
Alternatively, it is a chlorinated fluorinated hydrocarbon group in which part of the hydrogen atoms is replaced by chlorine atoms, and at least one or more fluorine atoms are bonded to carbon atoms.

The number of carbon atoms at this time may be arbitrary, but from the viewpoint of easy synthesis and availability as a raw material monomer, selectivity of polymerization reaction and saponification, etc., generally 10 or less, Further, it is appropriate to use a standard of 6 or less, and more preferably, it has 1 to 3 carbon atoms. The case where R ³ is a hydrocarbon group or a fluorinated hydrocarbon group is also considered as the same as described above.

Illustrative examples of fluorine-containing branched vinyl carboxylate having R ¹ , R ² and R ³ include, for example,
Vinyl perfluoropivalate, vinyl 2,2-bistrifluoromethylpropionate, vinyl chlorooctafluoropivalate, vinyl hexafluoro-2-chloromethylisobutyrate, vinyl perfluoroisobutyrate, vinyl hexafluoro-2-chloroisobutyrate, Examples thereof include vinyl perfluorocyclohexylcarboxylate and vinyl perfluoroadamantylcarboxylate. Among them, vinyl perfluoropivalate and vinyl 2,2-bistrifluoromethylpropionate are exemplified as particularly preferred.

The polymerization can be carried out by solution polymerization in addition to bulk polymerization, and a common organic solvent used for radical polymerization can be used as a solvent. As the polymerization initiator, an ordinary radical polymerization initiator such as an azo compound or a peroxide can be used. In order to accelerate the polymerization reaction, a sensitizer may be added or ultraviolet light may be irradiated.

The polymerization temperature is not particularly limited, but is 0 ° C. to 80 ° C.
It is preferably in the range of ° C. If the polymerization temperature is higher than 80 ° C., the syndiotacticity decreases, which is not preferable. On the other hand, when the polymerization temperature is too low, that is, lower than 0 ° C., the polymerizability is extremely reduced and productivity is lacking, which is not preferable.
In the polymerization of the invention of this application, monomers copolymerizable with a fluorine-containing branched vinyl carboxylate, for example, α-olefins such as ethylene, propylene and isobutene, acrylic acid, methacrylic acid, crotonic acid, maleic acid and itacone Acids, unsaturated acids such as maleic anhydride or salts thereof or mono- or dialkyl esters, acrylonitrile, methacrylonitriles, acrylamide, methacrylamides, vinyl ethers, vinyl chloride, vinylidene chloride, vinyl sulfonic acid or salts thereof in small amounts It is also possible for them to be present.

The PVA of the invention of this application is produced by saponifying the fluorine-containing polyvinyl ester obtained by the above polymerization, and the saponification method is not particularly limited, and an appropriate solvent is used. For example, a tetrahydrofuran solution can be saponified by a known method using an alkali such as sodium hydroxide or potassium hydroxide as a catalyst. Although the reason why the fluorine-containing branched carboxylic acid vinyl ester of the invention of the present application gives a PVA having a high syndiotacticity is not clear, the steric repulsion effect between the monomer and the growing radical due to branching of carbon adjacent to the side chain carbonyl, and It is presumed that the synergistic effect of both the electrostatic repulsion effect and the syndiotactic polymerization were more favorably exerted by the hydrogenated hydrocarbon group.

According to the method of the present invention, PVA having a high syndiotacticity of 65% or more can be produced even at a polymerization temperature of 0 ° C. or more. It is suitable for conductive materials and the like.

[0020]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples.
The invention of this application is not limited to the following examples unless it exceeds the gist. The measuring methods used in the examples and comparative examples are as follows. <Syndiotacticity (two twins)> 400 MHz NM
Proton NMR of PVA by R instrument (Varian)
Is measured to determine the proportion (%) of triads (mm / mr / rr), and from the following formula, syndiotacticity (dual) (%)
Was calculated.

Syndiotacticity (duplex) = rr + (mr / 2) <Degree of polymerization> Column (TSKgelGMHH, manufactured by Tosoh Corporation)
Gel permeation chromatograph (manufactured by JASCO Corporation) equipped with RH and G3000HHR) and a differential refractometer (manufactured by JASCO Corporation, RI-930), number average molecular weight of polyvinyl ester in a tetrahydrofuran solvent at 40 ° C. Was calculated in terms of polystyrene, and the degree of polymerization was calculated by dividing each by the molecular weight of the monomer. Example 1 Vinyl 2,2-bistrifluoromethylpropionate 1
1.8 parts by weight (0.15 mol / L) of 2,2′-azobisisobutyronitrile as a polymerization initiator was added to 00 parts by weight (5.8 mol / L), and polymerization was carried out at 60 ° C. for 3 hours. The product was diluted with acetone and reprecipitated in n-hexane, and the degree of polymerization of the polyvinyl ester obtained was determined by gel permeation chromatography. Further, a polyvinyl ester is dissolved in tetrahydrofuran and alkali-saponified to form PVA.
Was obtained, and syndiotacticity (duplet) was determined from proton NMR measurement of PVA. The results are shown in Table 1. Example 2 Vinyl 2,2-bistrifluoromethylpropionate 6
2.3 parts by weight (0.15 mol) of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 4 parts by weight (2.9 mol / L) and 36 parts by weight (50 vol%) of methanol.
/ L) In addition, under UV irradiation by a high pressure mercury lamp, 20
Polymerized at 24 ° C. for 24 hours. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Example 3 Vinyl 2,2-bistrifluoromethylpropionate 5
8 parts by weight (2.9 mol / L), tetrahydrofuran 4
3.1 parts by weight (0.15 mol / L) of benzoyl peroxide as a polymerization initiator was added to 2 parts by weight (50 vol%),
Polymerization was carried out at 20 ° C. for 24 hours under irradiation of ultraviolet rays by a high-pressure mercury lamp. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Example 4 100 parts by weight of vinyl perfluoropivalate (5.6 m
ol / L) of 1.5 parts by weight (0.15 mol / l) of 2,2'-azobisisobutyronitrile as a polymerization initiator.
L) and polymerized at 60 ° C. for 3 hours. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Example 5 79 parts by weight of vinyl perfluoropivalate (3.9 mo)
1 / L), 21 parts by weight of tetrahydrofuran (30 vol.
%), As a polymerization initiator, 1.7 parts by weight (0.15 mol / L) of 2,2'-azobisisobutyronitrile was added.
Polymerized for hours. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Example 6 100 parts by weight of vinyl hexafluoro-2-chloroisobutyrate (5.8 mol / L) were added with 2,2'- as a polymerization initiator.
1.7 parts by weight of azobisisobutyronitrile (0.15 parts)
mol / L) and polymerized at 60 ° C. for 3 hours. Example 1
The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in. The results are shown in Table 1. Comparative Example 1 1.3 parts by weight (0.07 mol / L) of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 100 parts by weight of vinyl pivalate (6.8 mol / L), and a high-pressure mercury lamp was added. Under ultraviolet irradiation at 0 ° C. for 24 hours. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 2 57 parts by weight of vinyl pivalate (3.4 mol / L), n
1.5 parts by weight (0.10 mol / L) of 2,2′-azobisisobutyronitrile as a polymerization initiator was added to 43 parts by weight (50 vol%) of hexane, and 20 ° C. under ultraviolet irradiation by a high pressure mercury lamp. For 24 hours. Example 1
The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in. The results are shown in Table 1. Comparative Example 3 1.5 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 100 parts by weight of vinyl 7H-dodecafluoroheptanoate (3.6 mol / L) (0.15 m
ol / L), and under ultraviolet irradiation by a high-pressure mercury lamp,
Polymerization was performed at 20 ° C. for 9 hours. The degree of polymerization was determined in the same manner as in Example 1. Further, polyvinyl ester was dissolved in methanol and alkali-saponified to obtain PVA, and a syndiotacticity (duplet) was obtained in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 4 67 parts by weight of vinyl 7H-dodecafluoroheptanoate (1.8 mol / L), 33 parts by weight of methanol (50 v
ol%), 2.0 parts by weight (0.15 mol / L) of 2,2'-azobisisobutyronitrile as a polymerization initiator was added, and irradiated with ultraviolet light from a high-pressure mercury lamp at 20 ° C for 24 hours.
Polymerization was carried out for a period of time, but the monomer was solvolyzed and no polymer was obtained.

[0022]

[Table 1]

[0023]

As described in detail above, according to the invention of this application, PVA having a high syndiotacticity of 65% or more can be efficiently and stably produced even at a polymerization temperature of 0 ° C. or more. . These are useful for high-strength high-modulus materials, heat-resistant materials, and the like.

[Procedure amendment]

[Submission date] November 26, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Patent application title: Method for producing polyvinyl alcohol rich in syndiotacticity

[Claims]

Embedded image (Wherein R ¹ and R ² each represent a fluorinated hydrocarbon group which may be partially substituted with a chlorine atom, and R ³ represents a hydrocarbon group, a fluorinated hydrocarbon group, a fluorine atom Or a chlorine atom), which is obtained by polymerizing a vinyl ester of a fluorine-containing branched carboxylic acid represented by the following formula (1) and then saponifying the polymer: (3) A method for producing polyvinyl alcohol having a syndiotacticity (duplex) of 65% or more.

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The invention of this application relates to polyvinyl alcohol (hereinafter referred to as PVA) having a high syndiotacticity.
). More specifically, the invention of this application relates to a method for producing a high syndiotactic PVA having a syndiotacticity of 65% or more, comprising polymerizing a fluorine-containing branched carboxylic acid vinyl ester and then saponifying the polymer. .

[0002]

2. Description of the Related Art In general, PVA is produced by saponifying a polyvinyl ester, particularly polyvinyl acetate, obtained by polymerization of an aliphatic vinyl ester with an alkali catalyst. It is well known that the physical properties of PVA greatly change due to the stereoregularity of the side chain hydroxyl group. That is, the higher the degree of isotacticity or syndiotacticity, the higher the crystallinity of PVA, and the higher the heat resistance and strength of molded products such as fibers and films. In particular, the increase in syndiotacticity leads to an increase in intermolecular hydrogen bonds, so that the physical properties are dramatically improved.

Generally, the stereoregularity of PVA obtained from polyvinyl acetate is as low as about 53% in syndiotacticity (duplex), and its tacticity does not change much even if the polymerization solvent or polymerization temperature is changed. As a method for obtaining PVA having a high syndiotacticity, there is known a method in which vinyl trifluoroacetate having a polar substituent or vinyl pivalate having a bulky substituent is polymerized and then saponified. For example, vinyl trifluoroacetate in n-nonane
When polymerized at 40 ° C, syndiotacticity of 63% P
VA is obtained (Makromol, Chem., 165, 2
17, p. 1973). However, the monomer vinyl trifluoroacetate has a problem that it is easily decomposed even by a very small amount of water and lacks storage stability.

Recently, vinyl pivalate has been polymerized in n-hexane at -40 ° C. to give syndiotactic-6.
It is reported that 9% of PVA is obtained (Polyme
r J., Vol. 29, No. 3, p. 293, 1997).
However, according to this report, the polymerization time is indeed as long as 10 days, which is not a level that can be carried out on a very industrial scale.
Further, in order to obtain PVA having a syndiotacticity of 65% or more, polymerization at a low temperature of 0 ° C. or less is indispensable, which is disadvantageous in terms of equipment, and the productivity is low due to a slow polymerization reaction. There is a problem. In addition, the obtained polyvinyl pivalate is less likely to be saponified and is usually reacted under violent alkaline conditions. Therefore, there is a problem that the PVA is colored by impurities such as trace amounts of oxygen in the reaction system.

[0005] On the other hand, it has long been reported that PVA having a syndiotacticity of 74% can be synthesized by saponifying a polymer obtained by low-temperature cationic polymerization of tin tetrachloride with trimethylsilyl vinyl ether in nitroethane (74%). Molecular Chemistry, 24, 606, 1967
Year). However, cationic polymerization is disadvantageous in that it is easily affected by impurities such as moisture in the air, and in this case, it is industrially disadvantageous because the polymerization temperature needs to be lowered to -78 ° C. The degree of polymerization of the PVA to be produced is extremely low at 30 and the physical properties such as the strength of the molded product are inevitably inadequate.

In addition, other than the above-mentioned vinyl trifluoroacetate,
Vinyl ester having a linear fluorinated hydrocarbon group
Has been studied in the past (Vysokomol
Soedin., Ser. B, Volume 9, Issue 1, Page 4, 1967
Year, and Kinet. Mech. Polyreactions, Int. Symp. Ma
cromol. Chem., Prepr., vol. 3, p. 249, 1969.
Year). And specifically, at 20 ° C., 7H-dodecafluoro
Vinyl heptanoate, CH _Two= CH-OCO (CF_TwoCF
_Two)_ThreeSyndiotacticity by polymerizing H
It is reported that 78% of PVA is obtained. Only
However, the experimental data in this report is only this one point.
The melting point of 236 ° C. of the obtained PVA is
Because it is the same level as
I have to say that there is. Actually, at 20 ° C
When you go, the syndiotacticity is 64%,
In addition, it drops to 61% at 60 ° C.

Further, Japanese Patent Application Laid-Open No. 62-204823 discloses a fluorine-substituted vinyl pivalate, CH ₂ ＣＨCH
—OCOC (CF ₃ ) _n (CH ₃ ) _3-n (n = 1-3)
A method for producing a gas separation element having high selective permeability by homo- and copolymerization of is disclosed. However, the obtained polyvinyl ester has not been converted to PVA, and there is no description about stereoregularity.

[0008]

SUMMARY OF THE INVENTION The invention of this application has been made in view of the state of the prior art as described above, and overcomes the limitations of the prior art, and has a high quality and physical properties. It is an object of the present invention to provide a new method for producing PVA that can efficiently and stably produce PVA having a high nervousness (duplex) of 65% or more at a polymerization temperature of 0 ° C. or more.

[0009]

In order to solve the above-mentioned problems, the present application first provides a first invention as follows.

[0010]

Embedded image

Wherein R ¹ and R ² each represent a fluorinated hydrocarbon group which may be partially substituted with a chlorine atom, and R ³ represents a hydrocarbon group or a fluorinated hydrocarbon group. ,
A method for producing PVA having a syndiotacticity (duplex) of at least 65%, comprising polymerizing a fluorine-containing branched carboxylic acid vinyl ester represented by a fluorine atom or a chlorine atom) and then saponifying the polymer. I will provide a.

This application also relates to the manufacturing method.
Thus, as a second invention, R¹And R ^TwoBut each
Having 1 to 3 carbon atoms which may be partially substituted with a chlorine atom
As a third aspect of the present invention, a method for producing a fluorinated hydrocarbon,
^ThreeIs a hydrocarbon group having 1 to 3 carbon atoms, or fluorinated carbon
In a fourth aspect, the method is a hydrogen group.¹And R^Two
Are each a trifluoromethyl group and R^ThreeIs a methyl group
Or a trifluoromethyl group, or even a fifth
The invention also provides a method of polymerizing at a temperature of 0 ° C. or higher.
You.

[0013]

Embodiments of the present invention will be described below in detail. First, the fluorine-containing branched carboxylic acid vinyl ester represented by the above formula will be described. In the formula, each of R ¹ and R ² is a group in which a part or all of the hydrogen atoms bonded to the carbon atom of the hydrocarbon group is fluorine. A fluorinated hydrocarbon group substituted by an atom,
Alternatively, it is a chlorinated fluorinated hydrocarbon group in which part of the hydrogen atoms is replaced by chlorine atoms, and at least one or more fluorine atoms are bonded to carbon atoms.

The number of carbon atoms at this time may be arbitrary, but from the viewpoint of easy synthesis and availability as a raw material monomer, selectivity of polymerization reaction and saponification, etc., generally 10 or less, Further, it is appropriate to use a standard of 6 or less, and more preferably, it has 1 to 3 carbon atoms. The case where R ³ is a hydrocarbon group or a fluorinated hydrocarbon group is also considered as the same as described above.

Illustrative examples of fluorine-containing branched vinyl carboxylate having R ¹ , R ² and R ³ include, for example,
Vinyl perfluoropivalate, vinyl 2,2-bistrifluoromethylpropionate, vinyl chlorooctafluoropivalate, vinyl hexafluoro-2-chloromethylisobutyrate, vinyl perfluoroisobutyrate, vinyl hexafluoro-2-chloroisobutyrate, Examples thereof include vinyl perfluorocyclohexylcarboxylate and vinyl perfluoroadamantylcarboxylate. Among them, vinyl perfluoropivalate and vinyl 2,2-bistrifluoromethylpropionate are exemplified as particularly preferred.

The polymerization can be carried out by solution polymerization in addition to bulk polymerization, and a common organic solvent used for radical polymerization can be used as a solvent. As the polymerization initiator, an ordinary radical polymerization initiator such as an azo compound or a peroxide can be used. In order to accelerate the polymerization reaction, a sensitizer may be added or ultraviolet light may be irradiated.

The polymerization temperature is not particularly limited, but is 0 ° C. to 80 ° C.
It is preferably in the range of ° C. If the polymerization temperature is higher than 80 ° C., the syndiotacticity decreases, which is not preferable. On the other hand, when the polymerization temperature is too low, that is, lower than 0 ° C., the polymerizability is extremely reduced and productivity is lacking, which is not preferable.
In the polymerization of the invention of this application, monomers copolymerizable with a fluorine-containing branched vinyl carboxylate, for example, α-olefins such as ethylene, propylene and isobutene, acrylic acid, methacrylic acid, crotonic acid, maleic acid and itacone Acids, unsaturated acids such as maleic anhydride or salts thereof or mono- or dialkyl esters, acrylonitrile, methacrylonitriles, acrylamide, methacrylamides, vinyl ethers, vinyl chloride, vinylidene chloride, vinyl sulfonic acid or salts thereof in small amounts It is also possible for them to be present.

The PVA of the invention of this application is produced by saponifying the fluorine-containing polyvinyl ester obtained by the above polymerization, and the saponification method is not particularly limited, and an appropriate solvent is used. For example, a tetrahydrofuran solution can be saponified by a known method using an alkali such as sodium hydroxide or potassium hydroxide as a catalyst. Although the reason why the fluorine-containing branched carboxylic acid vinyl ester of the invention of the present application gives a PVA having a high syndiotacticity is not clear, the steric repulsion effect between the monomer and the growing radical due to branching of carbon adjacent to the side chain carbonyl, and It is presumed that the synergistic effect of both the electrostatic repulsion effect and the syndiotactic polymerization were more favorably exerted by the hydrogenated hydrocarbon group.

According to the method of the present invention, PVA having a high syndiotacticity of 65% or more can be produced even at a polymerization temperature of 0 ° C. or more. It is suitable for conductive materials and the like.

[0020]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples.
The invention of this application is not limited to the following examples unless it exceeds the gist. The measuring methods used in the examples and comparative examples are as follows. <Syndiotacticity (two twins)> 400 MHz NM
Proton NMR of PVA by R instrument (Varian)
Is measured to determine the proportion (%) of triads (mm / mr / rr), and from the following formula, syndiotacticity (dual) (%)
Was calculated.

Syndiotacticity (duplex) = rr + (mr / 2) <Degree of polymerization> Column (TSKgelGMHH, manufactured by Tosoh Corporation)
Gel permeation chromatograph (manufactured by JASCO Corporation) equipped with RH and G3000HHR) and a differential refractometer (manufactured by JASCO Corporation, RI-930), number average molecular weight of polyvinyl ester in a tetrahydrofuran solvent at 40 ° C. Was calculated in terms of polystyrene, and the degree of polymerization was calculated by dividing each by the molecular weight of the monomer. Example 1 Vinyl 2,2-bistrifluoromethylpropionate 1
1.8 parts by weight (0.15 mol / L) of 2,2′-azobisisobutyronitrile as a polymerization initiator was added to 00 parts by weight (5.8 mol / L), and polymerization was carried out at 60 ° C. for 3 hours. The product was diluted with acetone and reprecipitated in n-hexane, and the degree of polymerization of the polyvinyl ester obtained was determined by gel permeation chromatography. Further, a polyvinyl ester is dissolved in tetrahydrofuran and alkali-saponified to form PVA.
Was obtained, and syndiotacticity (duplet) was determined from proton NMR measurement of PVA. The results are shown in Table 1. Example 2 Vinyl 2,2-bistrifluoromethylpropionate 6
2.3 parts by weight (0.15 mol) of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 4 parts by weight (2.9 mol / L) and 36 parts by weight (50 vol%) of methanol.
/ L) In addition, under UV irradiation by a high pressure mercury lamp, 20
Polymerized at 24 ° C. for 24 hours. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Example 3 Vinyl 2,2-bistrifluoromethylpropionate 5
8 parts by weight (2.9 mol / L), tetrahydrofuran 4
3.1 parts by weight (0.15 mol / L) of benzoyl peroxide as a polymerization initiator was added to 2 parts by weight (50 vol%),
Polymerization was carried out at 20 ° C. for 24 hours under irradiation of ultraviolet rays by a high-pressure mercury lamp. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Example 4 100 parts by weight of vinyl perfluoropivalate (5.6 m
ol / L) of 1.5 parts by weight (0.15 mol / l) of 2,2'-azobisisobutyronitrile as a polymerization initiator.
L) and polymerized at 60 ° C. for 3 hours. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Example 5 79 parts by weight of vinyl perfluoropivalate (3.9 mo)
1 / L), 21 parts by weight of tetrahydrofuran (30 vol.
%), As a polymerization initiator, 1.7 parts by weight (0.15 mol / L) of 2,2'-azobisisobutyronitrile was added.
Polymerized for hours. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Example 6 100 parts by weight of vinyl hexafluoro-2-chloroisobutyrate (5.8 mol / L) were added with 2,2'- as a polymerization initiator.
1.7 parts by weight of azobisisobutyronitrile (0.15 parts)
mol / L) and polymerized at 60 ° C. for 3 hours. Example 1
The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in. The results are shown in Table 1. Comparative Example 1 1.3 parts by weight (0.07 mol / L) of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 100 parts by weight of vinyl pivalate (6.8 mol / L), and a high-pressure mercury lamp was added. Under ultraviolet irradiation at 0 ° C. for 24 hours. The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 2 57 parts by weight of vinyl pivalate (3.4 mol / L), n
1.5 parts by weight (0.10 mol / L) of 2,2′-azobisisobutyronitrile as a polymerization initiator was added to 43 parts by weight (50 vol%) of hexane, and 20 ° C. under ultraviolet irradiation by a high-pressure mercury lamp. For 24 hours. Example 1
The degree of polymerization and syndiotacticity (duplex) were determined in the same manner as in. The results are shown in Table 1. Comparative Example 3 1.5 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 100 parts by weight of vinyl 7H-dodecafluoroheptanoate (3.6 mol / L) (0.15 m
ol / L), and under ultraviolet irradiation by a high-pressure mercury lamp,
Polymerization was performed at 20 ° C. for 9 hours. The degree of polymerization was determined in the same manner as in Example 1. Further, a polyvinyl ester was dissolved in methanol and alkali-saponified to obtain PVA, and a syndiotacticity (duplex) was obtained in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 4 67 parts by weight of vinyl 7H-dodecafluoroheptanoate (1.8 mol / L), 33 parts by weight of methanol (50 v
ol%), 2.0 parts by weight (0.15 mol / L) of 2,2'-azobisisobutyronitrile as a polymerization initiator was added, and the mixture was irradiated with ultraviolet light from a high-pressure mercury lamp at 20 ° C at 24 ° C.
Polymerization was carried out for a period of time, but the monomer was solvolyzed and no polymer was obtained.

[0022]

[Table 1]

[0023]

As described in detail above, according to the invention of this application, PVA having a high syndiotacticity of 65% or more can be efficiently and stably produced even at a polymerization temperature of 0 ° C. or more. . These are useful for high-strength high-modulus materials, heat-resistant materials, and the like.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Mitsuo Sawamoto, Inventor 920-23, 920-23, Haramachi, Shizuichi, Sakyo-ku, Kyoto-shi, Kyoto (72) Inventor Hiroshi Nakajima 23 Uji Kozakura, Uji-shi, Kyoto Unitika's Central Research Laboratory ( 72) Inventor Kazutoshi Terada 2045-1, Sakurazu, Kurashiki-shi, Okayama Pref.Kura Rekurashiki Research Laboratories Co., Ltd. (72) Inventor Daiji Ida Yoshida Honcho, Sakyo-ku, Kyoto-shi, Kyoto Prefecture Graduate School of Engineering, Kyoto University (72) Inventor Tetsuya Asahi 1-8, Kasumi, Yokkaichi-shi, Mie Prefecture Tosoh Corporation Yokkaichi Research Laboratory (72) Inventor Shoka Oki 1-8, Kasumi, Yokkaichi-shi, Mie Prefecture Yokkaichi Research Center (72) Inventor Yoshimichi Okano Aboshi Himeji, Hyogo Prefecture (12) Inventor Masamichi Nishimura 1239 Shinzai-ku, Himeji-shi, Hyogo Iseru Chemical Industry Co., Ltd. Research Institute in

Claims (5)

[Claims] 1. The following formula: (Wherein R ¹ and R ² each represent a fluorinated hydrocarbon group which may be partially substituted with a chlorine atom, and R ³ represents a hydrocarbon group, a fluorinated hydrocarbon group, a fluorine atom Or a chlorine atom), which is obtained by polymerizing a vinyl ester of a fluorine-containing branched carboxylic acid represented by the following formula (1) and then saponifying the polymer: (3) A method for producing polyvinyl alcohol having a syndiotacticity (duplex) of 65% or more. 2. The method according to claim 1, wherein R ¹ and R ² are each a fluorinated hydrocarbon group having 1 to 3 carbon atoms, a part of which may be substituted with a chlorine atom. 3. The method according to claim 1, wherein R ³ is a hydrocarbon group having 1 to 3 carbon atoms or a fluorinated hydrocarbon group. 4. The method according to claim 3, wherein R ¹ and R ² are each a trifluoromethyl group, and R ³ is a methyl group or a trifluoromethyl group. 5. The method according to claim 1, wherein the polymerization is carried out at a polymerization temperature of 0 ° C. or higher.