JPH07228625A - Modified polyvinyl alcohol - Google Patents

Abstract

(57) [Summary] [Structure] A modified polyvinyl alcohol having a specific hydroxyl group in its side chain. [Effect] The polyvinyl acetate emulsion produced by using the modified PVA of the present invention has a good appearance, a high viscosity, a small structural viscosity, and an excellent viscous behavior at the same time.
Moreover, it exhibits outstanding performance in that it has excellent stability when frozen and at high temperatures. Furthermore, the modified PVA of the present invention exhibits thermoplasticity without using a plasticizer, can be used as a resin that can be thermoformed, and is soluble in cold water even after thermoforming.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a modified polyvinyl alcohol (hereinafter, polyvinyl alcohol is abbreviated as PVA) useful as a dispersion stabilizer for emulsions and the like.

[0002]

2. Description of the Related Art A water-soluble polymer is used as a protective colloid,
It is known that a high-viscosity emulsion can be obtained by polymerizing vinyl ester monomers alone or together with ethylene or acrylic acid esters in an aqueous medium. These are adhesives, paints, paper processing. Although widely used for materials and the like, this emulsion is a non-Newtonian fluid and has the property that the apparent viscosity changes greatly with the shear rate (the structural viscosity is large). Therefore, this emulsion has a problem that workability is extremely hindered particularly when an application process is required such as an adhesive or a pressure-sensitive adhesive. That is, partially saponified PV
When a protective colloid such as A is used, safety and compatibility with various additives are excellent, and an emulsion having a relatively high viscosity is obtained, but the structural viscosity of the emulsion becomes large. On the other hand, when PVA having a high degree of saponification is used as the protective colloid, the structural viscosity becomes small, but the obtained emulsion has a low viscosity and tends to gel when left standing for a long period of time or added with an additive, and again after freezing. It becomes difficult to return to the original emulsion.

[0003]

An object of the present invention is to provide a novel modified PVA which is useful as a dispersion stabilizer for emulsions and which can be thermoformed and is soluble in cold water.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found a modified PVA having a structural unit (A) represented by the following general formula and completed the present invention. Came to let.

[0005]

[Chemical 2]

(N: integer of 3 to 20) Furthermore, in the above-mentioned modified PVA, a modified PVA having a structural unit (B) derived from an ethylenically unsaturated carboxylic acid, a lower alkyl ester thereof or an acid anhydride thereof was found. It was further,
In the above modified PVA, a modified PVA having a structural unit (D) derived from ethylenically unsaturated sulfonic acid was found.

The structural unit (A) in the present invention is the structural unit (A) represented by the above chemical formula 2. Structural unit (A)
N in is an integer of 3 to 20, preferably 4 to 15, and more preferably 5 to 10. 3-butene-1-all,
Structural units derived from 5-hexen-1-ol, 7-octen-1-ol, 9-decen-1-ol and the like can be mentioned. The structural unit (B) in the present invention is a structural unit derived from an ethylenically unsaturated carboxylic acid, its lower alkyl ester or its acid anhydride, and specifically, acrylic acid, methacrylic acid, crotonic acid, maleic acid. Acid, itaconic acid, acrylic acid ethyl ester, methacrylic acid methyl ester, crotonic acid methyl ester, citraconic acid,
Citraconic acid diethyl ester, maleic acid, maleic acid monomethyl ester, maleic acid diethyl ester,
Structural units derived from itaconic acid dimer ester, maleic anhydride, aconitic acid and the like, among them, citraconic acid, maleic acid, itaconic acid, maleic acid monomethyl ester, a structural unit derived from maleic anhydride is preferable, and further maleic acid. A structural unit derived from an acid, maleic anhydride, maleic acid monomethyl ester, or itaconic acid is more preferable. The structural unit (D) in the present invention is a structural unit derived from ethylenically unsaturated sulfonic acid, and specifically, olefin sulfonic acid such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid or a salt thereof. A sulfoalkylmaleate represented by the following chemical formula 3 or 4, a N-sulfoisobutylene acrylamide sodium salt represented by the following chemical formula 5, a sulfoalkyl (meth) acrylamide such as sodium 2-acrylamido-2-methylpropanesulfonate. , And sulfoalkyl (meth) acrylates such as sodium 2-sulfoethyl acrylate represented by the following chemical formula 6 below.

[0008]

[Chemical 3]

[0009]

[Chemical 4]

[0010]

[Chemical 5]

[0011]

[Chemical 6]

(In the above Chemical Formulas 3 to 6, R: an alkyl group, R ': an alkylene group, M: hydrogen, an alkali metal or ammonium ion, R ¹ : hydrogen or a methyl group, R ² : hydrogen or an alkyl group, respectively. means.)

The content of the above structural unit (A) in the present invention is not particularly limited, but when the modified PVA of the present invention is used as a protective colloid for emulsion polymerization of vinyl ester type monomers, the structural unit ( The content of A) is 0.1 to 15
Suitable is mol%, preferably 1 to 12 mol%. When the modified PVA of the present invention can be thermoformed and used as cold water-soluble PVA, the content of the structural unit (A) is 1 to 30.
Suitable is mol%, preferably 1 to 17 mol%. Also,
In the modified PVA of the present invention, when the structural unit (B) is contained, water solubility is remarkably improved. The content of the above structural unit (B) in the present invention is not particularly limited, but is preferably 0.1 to 10 mol%, and 0.1 to 5 mol%
Is more preferable. Further, in the modified PVA of the present invention, even when it contains the structural unit (D), the water solubility is remarkably improved. The above structural unit (D) in the present invention
The content of is not particularly limited, but is preferably 0.1 to 10 mol%, more preferably 0.1 to 55 mol%. The saponification degree of the modified PVA of the present invention is not particularly limited and may be completely saponified or partially saponified as long as the water solubility is substantially maintained, but 80 mol% or more is preferable. The degree of polymerization of the modified PVA of the present invention is not particularly limited, but with respect to the modified polyvinyl acetate obtained by acetylating the modified PVA by a conventional method, gel permeation chromatography at 30 ° C. using tetrahydrofuran as a solvent ( The weight average molecular weight in terms of standard polystyrene measured by GPC) is preferably 10,000 to 500,000,
00 to 300,000 is more preferable.

As the method for producing the modified PVA of the present invention, a copolymer obtained by copolymerizing a monomer that can be converted into the structural unit (A) and a vinyl ester such as vinyl acetate as a basic component is used as an alcohol. Obtained by saponification in solution. The copolymerization is carried out without solvent or in an alcohol solvent. As alcohols used at this time, lower alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol are used. There are no particular restrictions on the method of charging the monomer during polymerization, but the structural unit (B)
Alternatively, when a monomer convertible to the structural unit (D) is introduced, the structural unit (B) or the structure is added in the presence of the monomer convertible to the structural unit (A) and the vinyl ester (C). A method of dividing or continuously charging the monomer that can be converted to the unit (D) and a method of continuously charging these three components can be applied. As the catalyst used in the copolymerization, known radical catalysts such as α, α′-azobisisobutyronitrile and benzoyl peroxide are used. It is desirable to control the polymerization temperature between 58 and 65 ° C.

The copolymer obtained by the polymerization reaction is dissolved in alcohol, if necessary, hydrous alcohol, and saponified. Examples of alcohols used at this time include lower alcohols such as methyl alcohol and ethyl alcohol, and methyl alcohol is particularly preferably used. These alcohols may contain solvents such as acetone, acetic acid methyl ester, acetic acid ethyl ester and benzene as long as they are 40% by weight or less. As the catalyst used at the time of saponification, an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide, an alkali catalyst such as sodium methylate, or an acid catalyst such as mineral acid is used. The saponification temperature is not particularly limited, but a range of 20 to 50 ° C is suitable. As the saponification reaction proceeds as the saponification reaction proceeds, the product is crushed when a gel-like material is produced,
By thoroughly washing and drying, the modified P of the present invention
VA is obtained.

Since the modified PVA of the present invention has a hydrophobic group based on the structural unit (A) in the main chain, it has a high solution viscosity and an excellent function as a surfactant. Therefore, it is a dispersion stabilizer for emulsions. It is useful for Further, when it has a hydrophilic group based on the structural unit (B) or the structural unit (D), the water solubility is remarkably improved.

When the modified PVA of the present invention is used as a dispersion stabilizer for emulsion polymerization of vinyl ester-based monomer, the vinyl ester-based monomer of the present invention is added in the presence of water, protective colloid and water. A known polymerization method can be applied in which the modified PVA is charged temporarily, dividedly or continuously, and if necessary, the catalyst is also dividedly or continuously added while heating and stirring. When used as a protective colloid, the modified PVA of the present invention is preferably used in an amount of about 1 to 15% by weight, more preferably 2 to 12% by weight, based on the resin component of the dispersoid. As vinyl ester-based monomers, in addition to vinyl acetate, vinyl propionate, vinyl butyrate, 2,2,
4,4-tetramethylvalerianic acid, etc. are listed, and vinyl chloride, ethylene, (meth) acrylic acid ester is copolymerized with these monomers, or a small amount of acrylic acid,
Methacrylic acid, crotonic acid, itaconic acid, maleic anhydride, etc. can also be copolymerized.

The modified PVA of the present invention comprises, in addition to the above dispersion stabilizer for emulsion polymerization, a surfactant for various uses, wood, paper,
For applications such as adhesives such as aluminum foil, non-woven fabric binders, paints, fiber processing agents, paper clear coating agents, paper strength enhancers, pigment binders, fiber glues, and hydrophobic fiber glues such as polyester. It is useful.

[0019]

EXAMPLES Next, the present invention will be described more specifically with reference to examples.

Example 1 Vinyl acetate was added to a polymerization tank equipped with a reflux condenser, a stirrer, a thermometer, a nitrogen introducing pipe, a charging port for a post-added liquid and a pump.
6.4 g and 4.3 g of 3-butene-1-ol were charged. While stirring the polymerization solution, substitute nitrogen in the system and heat in a constant temperature bath. When the temperature reached 60 ° C, add 0.3 g of 2,2'-azobisisobutyronitrile into the system and polymerize. Started. Polymerization was performed from the start of polymerization while analyzing the solid content concentration in the polymerization system, and after 5 hours, the polymerization tank was cooled to stop the polymerization. The solid content concentration before the termination of the polymerization was 30% by weight.
The resulting polymerized paste was dropped into n-hexane to obtain a polymer. The content of 3-buten-1-ol units in the obtained polymer was 13.1 mol%. Next, a 20 wt% methanol solution of the polymer was prepared, and while stirring 46 ml of the solution at 40 ° C., 2 ml of a 10 wt% methanol solution of sodium hydroxide was prepared.
In addition, it was saponified. The gel-like substance was pulverized, washed with methanol, and dried at 50 ° C. for 18 hours to obtain a white powder of modified PVA.
The polymer structure was analyzed by nuclear magnetic resonance spectroscopy and summarized in Table 1.

Example 2 The following polymerization was carried out in the same manner using the same reactor as in Example 1. 46.4 g of vinyl acetate, 5-hexene-1-
I charged 6.0 g of oars. While stirring the polymerization solution, substitute nitrogen in the system and heat in a constant temperature bath. When the temperature reached 60 ° C, add 0.3 g of 2,2'-azobisisobutyronitrile into the system and polymerize. Started. Polymerization was carried out while analyzing the solid content concentration in the polymerization system from the start of the polymerization, and the polymerization was stopped after 6 hours by cooling the polymerization tank. The solid content concentration before the termination of the polymerization was 20% by weight. The polymerized paste obtained
A polymer was obtained by dropping into n-hexane. The content of 5-hexen-1-ol units in the obtained polymer was 11.0 mol%. Then, prepare a 20 wt% methanol solution of the polymer,
While stirring 46 ml of the solution at 40 ° C., sodium hydroxide
Saponification was performed by adding 2 ml of a 10 wt% methanol solution. The gel-like substance was pulverized, washed with methanol, and dried at 50 ° C. for 18 hours to obtain a white powder of modified PVA. The polymer structure was analyzed by nuclear magnetic resonance spectroscopy and summarized in Table 1.

Example 3 The following polymerization was carried out in the same manner using the same reactor as in Example 1. Vinyl acetate 46.4g, 4-buten-1-ol 4.3g, itaconic acid 0.04g, methanol 12g
I prepared it. While stirring the polymerization solution, substitute nitrogen in the system and heat in a constant temperature bath. When the temperature reached 60 ° C, add 0.6 g of 2,2'-azobisisobutyronitrile to the system and polymerize. Started. From the start of the polymerization, the solid content concentration in the polymerization system was analyzed, and the polymerization was carried out while dropping a 25 wt% methanol solution of itaconic acid, and 4 ml was added almost uniformly over 3 hours, and then the polymerization tank was cooled. Then, the polymerization was stopped. The solid content concentration before the termination of the polymerization was 20% by weight. The resulting polymerized paste was dropped into n-hexane to obtain a polymer. The content of 4-buten-1-ol units in the obtained polymer was 11.0 mol% and the content of itaconic acid units was 1.2 mol%. Then, a 20 wt% methanol solution of the polymer was prepared, and while stirring 46 ml of the solution at 40 ° C., 2 ml of a 10 wt% methanol solution of sodium hydroxide was added to perform saponification.
The gel-like substance was pulverized, washed with methanol, and dried at 50 ° C. for 18 hours to obtain a white powder of modified PVA. The polymer structure was analyzed by nuclear magnetic resonance spectroscopy and summarized in Table 1.

Example 4 The following polymerization was carried out by the same method using the same reactor as in Example 1. 46.4 g of vinyl acetate, 5-hexene-1-
Oat 6.0 g, maleic acid 0.05 g, methanol 12
g prepared. While stirring the polymerization solution, the system was replaced with nitrogen and heated in a thermostat, and when the temperature reached 60 ° C, 2,2'-
0.6 g of azobisisobutyronitrile was added to the system to initiate polymerization. From the start of the polymerization, the solid content concentration in the polymerization system was analyzed and the polymerization was carried out while dropping a 25 wt% methanol solution of maleic acid, and 4 ml was dripped almost uniformly within 4 hours, and then the polymerization tank was cooled. Then, the polymerization was stopped. The solid content concentration before the termination of the polymerization was 20% by weight. The resulting polymerized paste was dropped into n-hexane to obtain a polymer. The content of 5-hexen-1-ol units in the obtained polymer was 8.0 mol% and the content of itaconic acid units was 1.8%. Then, a 20 wt% methanol solution of the polymer was prepared, and while stirring 46 ml of the solution at 40 ° C., 2 ml of a 10 wt% methanol solution of sodium hydroxide was added to perform saponification.
The gel-like substance was pulverized, washed with methanol, and dried at 50 ° C. for 18 hours to obtain a white powder of modified PVA. The polymer structure was analyzed by nuclear magnetic resonance spectroscopy and summarized in Table 1.

Comparative Examples 1 to 4 For comparison, in Comparative Example 1, the content of branched fatty acid vinyl ester having an average carbon number of 10 was 5 mol% (structural unit (A)
And the content of the structural unit (B) is 0 mol%), and in Comparative Example 2, the content of the branched fatty acid vinyl ester having an average carbon number of 10 is 3 mol% (the content of the structural unit (A) and the structural unit (B) is 0). Mol%), and in Comparative Example 3, the content of itaconic acid was 2
Mol% (content of structural unit (A) 0 mol%), Comparative Example 4
Then, a PVA-based polymer was produced in the same manner as in Example 1 except that the content of maleic anhydride was 1 mol% (the content of the structural unit (A) was 0 mol%). Obtained P
The performance of the VA-based polymer is shown in Table 1. The obtained PVA-based polymer had no water solubility at all and only swelled in hot water, or the aqueous solution had a low viscosity even though it had good water solubility. The results are summarized in Table 1.

[0025]

[Table 1]

1) Water solubility: Prepare a 7.5 wt% aqueous solution,
The evaluation results are shown by the following symbols. (⊚: transparent, ×: there was undissolved content) 2) Thermoformability: hot press at 220 ° C., and the evaluation results are shown by the following symbols. (◎: good heat pressability, ×: poor heat pressability)

Example 5 The following polymerization was carried out in the same manner as in Example 1 using a 3 L scale reactor. 1680 g of vinyl acetate, 390 g of 7-octen-1-ol and 420 g of methanol were charged. While stirring the polymerization solution, the system was replaced with nitrogen in the system and heated in a constant temperature bath, and when the temperature reached a constant temperature of 60 ° C, 30 g of 2,2-azobisisobutyronitrile was added to the system to initiate polymerization. . From the start of the polymerization, the polymerization was carried out while analyzing the solid content concentration in the polymerization system, and the polymerization was stopped after 4 hours by cooling the polymerization tank. The polymerization rate before the termination of the polymerization was 56%. The resulting polymerized paste was dropped into n-hexane to obtain a polymer.
The content of 7-octen-1-ol unit in the obtained polymer was
It was 5.0 mol%. Next, a 25 wt% methanol solution of the polymer was prepared, and a 10 wt% methanol solution of sodium hydroxide was added to the polyvinyl acetate at a molar ratio of 0.10. While stirring the solution at 40 ° C. It saponified.
The gel-like substance was pulverized, washed with methanol, and dried at 50 ° C. for 18 hours to obtain a white powder of modified PVA. The polymer structure was analyzed by nuclear magnetic resonance spectroscopy and summarized in Table 2.

Example 6 The following polymerization was carried out in the same manner as in Example 1 using a 5 L scale reactor. 2800 g of vinyl acetate and 119 g of 7-octen-1-ol were charged. While stirring the polymerization solution,
The system was replaced with nitrogen in the system and heated in a thermostat, and when the temperature reached 60 ° C, 6.0 g of 2,2-azobisisobutyronitrile was added to the system to initiate polymerization. Polymerization was performed from the start of polymerization while analyzing the solid content concentration in the polymerization system, and after 5 hours, the polymerization tank was cooled to stop the polymerization. The polymerization rate before the termination of the polymerization was 42%. The obtained polymerized paste is n-
It was dropped into hexane to obtain a polymer. In the obtained polymer
The content of 7-octen-1-ol units was 3.1 mol%. Next, a 20 wt% methanol solution of the polymer was prepared,
While stirring the solution at 40 ° C, a 10 wt% methanol solution of sodium hydroxide was added to the polyvinyl acetate in a molar ratio of 0.
The mixture was added to 10 and saponified. The gel-like substance was pulverized, washed with methanol, and dried at 50 ° C. for 18 hours to obtain a white powder of modified PVA. The polymer structure was analyzed by nuclear magnetic resonance spectroscopy and summarized in Table 2.

Example 7 The following polymerization was carried out in the same manner using the same reactor as in Example 6. 2800 g of vinyl acetate, 7-octene-1-
300 g of oar and 700 g of methanol were charged. While stirring the polymerization solution, replace the nitrogen in the system and heat in a constant temperature bath.
When the temperature became constant at ℃, 33 g of 2,2-azobisisobutyronitrile was added to the system to initiate polymerization. Polymerization was performed while analyzing the solid content concentration in the polymerization system from the start of polymerization, and 4.
After 5 hours, the polymerization was stopped by cooling the polymerization tank. The polymerization rate before the termination of the polymerization was 63%. The resulting polymerized paste was dropped into n-hexane to obtain a polymer. The content of 7-octen-1-ol units in the obtained polymer was 8.4.
It was mol%. Next, a 25 wt% methanol solution of the polymer was prepared, and a 10 wt% methanol solution of sodium hydroxide was added to the polyvinyl acetate at a molar ratio of 0.10. While stirring the solution at 40 ° C. It saponified. The gel-like substance was pulverized, washed with methanol, and dried at 50 ° C. for 18 hours to obtain a white powder of modified PVA. The polymer structure was analyzed by nuclear magnetic resonance spectroscopy and summarized in Table 2.

Example 8 The following polymerization was carried out by the same method using the same reactor as in Example 6. 2800 g of vinyl acetate, 7-octene-1-
800 g of oats and 30 g of sodium allylsulfonate were charged. While stirring the polymerization solution, the system was replaced with nitrogen in the system and heated in a constant temperature bath, and when the temperature reached a constant temperature of 60 ° C, 30 g of 2,2-azobisisobutyronitrile was added to the system to initiate polymerization. . Polymerization was performed from the start of polymerization while analyzing the solid content concentration in the polymerization system, and after 5 hours, the polymerization tank was cooled to stop the polymerization. The polymerization rate before the termination of the polymerization was 38%.
The resulting polymerized paste was dropped into n-hexane to obtain a polymer. In the obtained polymer, the content of 7-octen-1-ol unit was 11.0 mol% and the content of sodium allylsulfonate unit was 0.5 mol%. Then 25% by weight of the polymer
A methanol solution was prepared, and a 10 wt% methanol solution of sodium hydroxide was added to the polyvinyl acetate at a molar ratio of 0.010 with stirring at 40 ° C. to saponify the solution. The gel was crushed and washed with methanol,
It was dried at ℃ for 18 hours to obtain modified PVA as white powder. The polymer structure was analyzed by nuclear magnetic resonance spectroscopy and summarized in Table 2.

Comparative Example 5 The following polymerization was carried out in the same manner using the same reactor as in Example 6. 2800 g of vinyl acetate, 25 g of sodium allylsulfonate and 700 g of methanol were charged. While stirring the polymerization liquid, replace the nitrogen in the system and heat in a constant temperature bath,
When the temperature reached 60 ° C, 1.5 g of 2,2-azobisisobutyronitrile was added to the system to initiate polymerization. Polymerization is performed while analyzing the solid content concentration in the polymerization system from the start of polymerization,
Polymerization was stopped by cooling the polymerization tank after 4 hours. The polymerization rate before the termination of the polymerization was 62%. The resulting polymerized paste was dropped into n-hexane to obtain a polymer. The content of sodium allylsulfonate unit in the obtained polymer was 0.5 mol%. Next, a 30 wt% methanol solution of the polymer was prepared, and a 10 wt% methanol solution of sodium hydroxide was added to the polyvinyl acetate at a molar ratio of 0.008 while stirring the solution at 40 ° C. It saponified. The gel was crushed and washed with methanol, then at 50 ° C for 18
After drying for an hour, a white powder of modified PVA was obtained. The polymer structure was analyzed by nuclear magnetic resonance spectroscopy and summarized in Table 2.

[0032]

[Table 2]

1) Water solubility: Prepare a 7.5 wt% aqueous solution,
The evaluation results are shown by the following symbols. (◎: transparent, ×:
2) Thermoformability: hot-pressed at 220 ° C., and the evaluation results are shown by the following symbols. (◎: good heat pressability, ×: poor heat pressability)

[0034]

As is apparent from the above examples, the polyvinyl acetate emulsion produced by using the modified PVA of the present invention has a good appearance and a high viscosity, and at the same time has a small structural viscosity and an excellent viscosity. It behaves and exhibits outstanding performance in that it has excellent stability when frozen and at high temperatures. Furthermore, the modified PVA of the present invention exhibits thermoplasticity without using a plasticizer, can be used as a resin that can be thermoformed, and is soluble in cold water even after thermoforming.

Front Page Continuation (72) Inventor Yufumi Hatanaka, 1 Kuraray Co., Ltd., 2045, Satsuki, Kurashiki, Okayama Prefecture (72) Inventor Masao Tsuji 1 Kuraray Co., Ltd., 2045, Sakkazu, Kurashiki, Okayama (72) Inventor, Fujiwara Naoki, 1621 Sakazu, Kurashiki, Okayama Prefecture Kuraray Co., Ltd. (72) Inventor Ken Kusunoki, 1621 Sakazu Sakurazu, Kurashiki, Okayama (72) Inventor Toshiaki Sato 1621 Satsuki, Kurashiki, Okayama Kura Co., Ltd. Within

Claims (3)

[Claims] 1. A structural unit (A) represented by the following general formula:
Modified polyvinyl alcohol having. [Chemical 1] (N: integer of 3 to 20) 2. The modified polyvinyl alcohol according to claim 1, which has a structural unit (B) derived from an ethylenically unsaturated carboxylic acid, a lower alkyl ester thereof or an acid anhydride thereof. 3. The modified polyvinyl alcohol according to claim 1, which has a structural unit (D) derived from an ethylenically unsaturated sulfonic acid.