JP4319177B2 - Modified polyvinyl alcohol and dispersant using the same - Google Patents

Description

The present invention relates to a modified polyvinyl alcohol having a double bond derived from a specific monomer in the main chain, and a dispersant using the same.

As polyvinyl alcohol having a reactive unsaturated double bond introduced into the molecule, polyvinyl alcohol (hereinafter referred to as PVA) is post-modified with a reactive molecule containing a polymerizable double bond. Obtained by introducing an unsaturated double bond into the side chain of PVA (for example, see Patent Document 1) and a polyvinyl ester copolymer having a protected ethylenically unsaturated double bond. Those obtained after removing the protection (for example, see Patent Document 2), those obtained by introducing an unsaturated double bond at the end of the PVA molecule using an aldehyde as a chain transfer agent (for example, see Patent Document 3) Etc. are known.

JP 04-283749 A JP 2001-072720 A JP 2004-250695 A

An object of the present invention is to provide a modified PVA having an unsaturated double derived from a specific monomer in the main chain in the molecule and a dispersant using the same.

The above problem can be solved by copolymerizing a specific monomer and carrying out a saponification reaction.

That is, the present invention is a modified PVA having a saponification degree of 20 to 60% and an average polymerization degree of 100 to 1000, which contains a bond unit represented by the general formula (Formula 9) in the molecular main chain. In this case, the absorbance at 270 nm according to the ultraviolet absorption spectrum of 0.2% by mass of an aqueous solution, methanol solution or aqueous methanol mixed solution is preferably 0.05 or more, and the amount of unmodified PVA is preferably 25% or less. .
(In formula, X1 and X2 represent a C1-C12 lower alkyl group, a hydrogen atom, or a metal salt. G represents the integer of 0-3. H represents the integer of 0-12. Y1. Represents a carboxylic acid, a carboxylic acid ester, a carboxylic acid metal salt or a hydrogen atom.)

A modified PVA having an unsaturated double derived from a specific monomer in the main chain in the molecule is obtained.

The modified PVA is obtained by copolymerizing a monomer having an ethylenically unsaturated double bond and a monomer having a vinyl ester unit and then saponifying to obtain a carbonyl group-containing PVA, washing and drying. There is a random introduction of an unsaturated double bond starting from a carboxyl group in the main chain.

As the monomer having an ethylenically unsaturated double bond, those represented by the general formula (Formula 10) can be suitably used.
(Wherein X3 and X4 represent a lower alkyl group having 1 to 12 carbon atoms or a hydrogen atom. I represents an integer of 0 to 12. Y2 represents a carboxylic acid, a carboxylic acid ester, a carboxylic acid metal salt, or Represents a hydrogen atom.)
Examples of these monomers include dimethyl maleate and diethyl maleate.

Moreover, the monomer represented by the general formula (Chemical Formula 11) can also be suitably used.
(In the formula, X5 and X6 represent a lower alkyl group having 1 to 12 carbon atoms or a hydrogen atom. J represents an integer of 0 to 12. Y3 represents a carboxylic acid, a carboxylic acid ester, a carboxylic acid metal salt, or Represents a hydrogen atom.)
Examples of these monomers include dimethyl fumarate, monoethyl fumarate, diethyl fumarate, dimethyl citraconic acid and the like.

Moreover, the monomer represented by the general formula (Chemical Formula 12) can also be suitably used.
(In the formula, k represents an integer of 0 to 12. Y4 represents a carboxylic acid, a carboxylic acid ester, a carboxylic acid metal salt, or a hydrogen atom.)
Examples of these monomers include maleic anhydride and citraconic anhydride.

The content (copolymerization amount) of these monomers is not particularly limited, but is preferably 0.1 to 50 mol% from the viewpoint of securing the amount of unsaturated double bonds in the molecule and water solubility, 1-10 mol% is more preferable.

The monomer having a vinyl ester unit is not particularly limited, but vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate In addition, vinyl acetate is preferable from the viewpoint of stable polymerization.

Moreover, you may copolymerize the monomer which can be copolymerized with these monomers as needed. The copolymerizable monomer is not particularly limited, but examples thereof include olefins such as ethylene, propylene, 1-butene and isobutene, acrylic acid, methacrylic acid, crotonic acid, phthalic acid, maleic acid, itaconic acid and the like. Monomer having an anionic group, or a salt thereof, monoalkyl ester or dialkyl ester having 1 to 18 carbon atoms, acrylamide, N-alkyl acrylamide having 1 to 18 carbon atoms, N, N-dialkyl acrylamide, diacetone Acrylamides such as acrylamide, 2-acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts or quaternary salts thereof, methacrylamide, N-alkylmethacrylamide having 1 to 18 carbon atoms, N, N-dialkylmedium Methacrylamides such as chloramide, diacetone methacrylamide, 2-methacrylamide propanesulfonic acid and salts thereof, methacrylamide propyldimethylamine and salts or quaternary salts thereof, alkyl vinyl ethers having an alkyl chain length of 1 to 18 carbon atoms , Vinyl ethers such as hydroxyalkyl vinyl ether and alkoxyalkyl vinyl ether, N-vinyl amides such as N-vinyl pyrrolidone, N-vinyl formamide, N-vinyl acetamide, vinyl cyanides such as acrylonitrile and methacrylonitrile, vinyl chloride, chloride Vinyl halides such as vinylidene, vinyl fluoride, vinylidene fluoride, vinyl bromide, vinylidene bromide, vinyl silanes such as trimethoxyvinyl silane, allyl acetate, allyl chloride Allyl alcohol, allyl compounds such as dimethyl allyl alcohol, vinyl silyl compounds such as vinyltrimethoxysilane, there is isopropenyl acetate and the like. Although the usage-amount of these copolymerizable monomers is not specifically limited, 0.001-20 mol% is preferable with respect to all the monomers to be used. When itaconic acid is used as the copolymerizable monomer, the content (copolymerization amount) of the itaconic acid monomer is preferably 0.05 to 10 mol%, more preferably 0.1 to 3 mol%.

The average degree of polymerization of the modified PVA is in the range of 100 to 1000, preferably in the range of 200 to 800, from the viewpoint of improving the affinity with the monomer and the balance of protective colloid properties.

The method for polymerizing the monomer is not particularly limited, and a known polymerization method is used, and solution polymerization is usually performed using an alcohol such as methanol, ethanol or isopropyl alcohol as a solvent. Bulk polymerization, emulsion polymerization, and suspension polymerization can also be performed. Such solution polymerization may be continuous polymerization or batch polymerization, and the monomer may be charged in a divided manner, may be charged all at once, or any means such as adding continuously or intermittently may be used.

The polymerization initiator used in the solution polymerization is not particularly limited, but azobisisobutyronitrile, azobis-2,4-dimethylpareronitrile, azobis (4-methoxy-2,4-dimethylpareronitrile). ) And other azo compounds, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, acetylcyclohexylsulfonyl peroxide, peroxides such as 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, and diisopropylpropyl Percarbonate compounds such as dicarbonate, di-2-ethylhexyl peroxydicarbonate, diethoxyethyl peroxydicarbonate, t-butylperoxyneodecanate, α-cumylperoxyneodecanate, t-butylperoxyneo Decanate The perester compound, azobisdimethylvaleronitrile can be used a known radical polymerization initiator such as azo-bis-methoxy valeronitrile. The polymerization reaction temperature is usually selected from the range of about 30 ° C to 90 ° C.

In saponification, a copolymer obtained by copolymerizing monomers is dissolved in alcohol, and an ester in the molecule is hydrolyzed in the presence of an alkali catalyst or an acid catalyst. Examples of the alcohol include methanol, ethanol, butanol and the like. The concentration of the copolymer in the alcohol is not particularly limited, but is selected from a range of 10 to 80% by weight. As the alkali catalyst, for example, alkali catalysts such as alkali metal hydroxides and alcoholates such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate and potassium methylate can be used. For example, an inorganic acid aqueous solution such as hydrochloric acid or sulfuric acid, or an organic acid such as p-toluenesulfonic acid can be used. These catalysts are preferably used in an amount of 1 to 100 mmol equivalents relative to the copolymer. The saponification temperature is not particularly limited, but is in the range of 10 to 70 ° C, preferably 30 to 40 ° C. Although reaction time is not specifically limited, It is performed over 30 minutes-3 hours.

The absorbance of the modified PVA is not particularly limited, but it is preferable that the absorbance at 270 nm of 0.2% by mass of an aqueous solution, a methanol solution or a water-methanol mixed solution is 0.05 or more. This absorbance can be adjusted to any value by changing the amount of catalyst used in the saponification step, the saponification time, and the saponification temperature.

Here, regarding the attribution of the ultraviolet absorption spectrum, in JP-A-2004-250695, etc., the absorption at 215 nm is attributed to the structure of —CO—CH═CH— in the PVA resin, and the absorption at 280 nm is in the PVA resin. Bruno -CO- (CH = _{CH) 2} - belong to the structure of the absorption of 320nm is the -CO- (CH = _{CH) 3} in PVA-based resin - there is a description that relates to belong to the structure of.

The UV absorption spectrum derived from the double-chain structure (—CO— (CH═CH) ₂ —) of an unsaturated double bond of PVA using a general aldehyde as a chain transfer agent has a peak top near 280 nm. The modified PVA of the present invention is derived from the structure of the general formula (Formula 13) and has a peak included in the range of 265 to 275 nm at the center of 270 nm.

The degree of saponification of the modified PVA is in the range of 20 to 60%, and preferably in the range of 35 to 45%, from the viewpoint of improving the balance of water solubility, affinity with monomers, and protective colloid properties.

The modified PVA of the present invention is used, for example, for suspension polymerization of vinyl chloride. Specifically, in a method for producing a vinyl chloride polymer by suspension polymerization of vinyl chloride or a mixture of monomers copolymerizable with vinyl chloride in an aqueous medium of a polymerization initiator and a dispersant, (1) A method in which the modified PVA of the present invention and a dispersant other than (2) and (1) are used in combination.
(2) Examples of the dispersant other than (1) include gelatin, methyl cellulose, hydroxypropyl cellulose, and PVA other than (1). Among these, PVA having a saponification degree of 60 to 99% and an average polymerization degree of 1500 to 3000 is preferable from the viewpoint of improving the physical properties of the vinyl chloride resin.

(1) The use amount of the modified PVA of the present invention is preferably 0.005 to 0.3 parts by mass with respect to 100 parts by mass of vinyl chloride or a mixture of monomers copolymerizable with vinyl chloride, 0.1 mass part is more preferable. (2) The amount of the dispersant other than (1) is preferably 0.01 to 0.3 parts by weight with respect to 100 parts by weight of vinyl chloride or a mixture of monomers copolymerizable with vinyl chloride. 04-0.15 mass part is more preferable.

For example, the suspension polymerization is performed in the presence of a polymerization initiator by adding the dispersants (1) and (2) to water and dispersing vinyl chloride or a monomer copolymerizable with vinyl chloride. As a polymerization initiator, the polymerization initiator used in the above-mentioned solution polymerization is mentioned.
The polymerization temperature is selected from the range of 30 to 70 ° C, for example. The ratio of vinyl chloride or a mixture of monomers copolymerizable with vinyl chloride and water is preferably 1: 0.9 to 1: 3, more preferably 1: 1 to 1: 1.5, in terms of mass ratio.

Hereinafter, the present invention will be described in more detail with reference to examples.
Unless otherwise specified, “parts” and “%” mean “parts by mass” and “mass%”.

Example 1
<Manufacture of modified PVA>
10 parts of vinyl acetate, 21 parts of methanol, 0.023 part of dimethyl maleate and 0.10% azobisisobutyronitrile with respect to vinyl acetate are charged into a polymerization vessel, heated after nitrogen substitution and heated to the boiling point. Furthermore, a mixed solution of 3.5 parts of vinyl acetate, 7.5 parts of methanol and 0.203 parts of dimethyl maleate was continuously added until the polymerization rate reached 75%, and the polymerization rate reached 90%. At that time, the polymerization was stopped. Subsequently, unpolymerized vinyl acetate is removed by a conventional method, and the resulting polymer is saponified with sodium hydroxide by a conventional method and dried to obtain an average polymerization degree of 400, a saponification degree of 39.0 mol%, and dimethyl maleate. A modified PVA having an absorbance of 1.1 mol% at a wavelength of 270 nm of an aqueous solution of 1.0 mol% and a non-modified PVA amount of 17% was obtained.

<Analysis method>
The saponification degree of PVA was measured according to JIS K 6726 “3.5 saponification degree”, and the average polymerization degree of PVA was measured according to JIS K 6726 “3.7 average polymerization degree”. Is. The content of dimethyl maleate is measured by ¹ H-NMR and ¹³ C-NMR. The unmodified PVA content was determined by completely saponifying the modified PVA with an alkali catalyst in methanol, adjusting the Soxhlet-extracted sample to a 0.01 w / v% aqueous solution, using ion exclusion HPLC, and an IR detector. It is calculated by the area ratio. The 270 nm absorbance is obtained by measuring the absorbance of ultraviolet light at 270 nm after adjusting the modified PVA to a 0.2 mass% aqueous solution.

<Photocurability>
5 parts of modified PVA was dissolved in 45 parts of water to prepare an about 10% aqueous solution, and 0.005 part of a photopolymerization initiator (Irgacure 2959; manufactured by Nagase Sangyo Co., Ltd.) was added to the aqueous solution to perform UV irradiation. .

<Suspension polymerization of vinyl chloride>
In a 100 L stainless steel autoclave equipped with a stirrer, 14 kg of water at 30 ° C. with stirring, 0.02 part by mass of the modified PVA obtained as a dispersant (1) with respect to 100 parts by mass of the vinyl chloride monomer described later, Non-modified PVA (trade name: Denkapoval W-20N, average polymerization degree 2200, saponification degree 79-80%, Denki Kagaku Kogyo Co., Ltd.) 0.12 parts by mass as dispersant (2), di-polymerization initiator 0.012 kg each of 2-ethylhexyl peroxydicarbonate and azobisdimethylvaleronitrile was charged. After degassing the autoclave in vacuum, 10 kg of vinyl chloride monomer was added and polymerized at 50 ° C. for 10 hours. The physical properties of the obtained vinyl chloride resin were measured according to the following methods.

<Evaluation of pore volume>
This indicates the porosity of the vinyl chloride particles, and is a value obtained by measuring a pore radius of 75 to 75000 angstroms using a mercury intrusion porosimeter model 65 manufactured by CARLO ERBA.

<Evaluation of particle size distribution>
It is an average particle diameter obtained by measuring according to JISZ-8801.

<Bulk specific gravity>
It measured according to JIS K-6721.

<Plasticizer absorption>
Glass fiber was packed in the bottom of an aluminum alloy container having an inner diameter of 25 mm and a depth of 85 mm, and 10 g of vinyl chloride resin was charged. To this was added 15 ml of a plasticizer (dioctyl phthalate, hereinafter referred to as DOP), and the mixture was allowed to stand for 30 minutes to fully penetrate the DOP into the vinyl chloride resin. Thereafter, excess DOP was centrifuged at an acceleration of 1500 G, and the amount of DOP absorbed in 10 g of the vinyl chloride resin was measured and converted to an amount per 100% by mass of the vinyl chloride resin.

<Fisheye>
After mixing 100 g of vinyl chloride resin, 50 g of DOP, 3 g of cadmium / barium stabilizer and 0.2 g of ultramarine, kneaded with a roll at a temperature of 150 ° C. for 3 minutes for 5 minutes to produce a sheet, which is present in 100 cm ^{2 of} the sheet I counted the number of fish eyes.

Examples 2-3 and Comparative Example 1
Dispersion made of modified PVA in the same manner as in Example 1 except that the degree of saponification, molecular weight (Mn), the type of monomer having an ethylenically unsaturated double bond, and the amount of modification were changed as shown in Table 1. Agent (1) was prepared and evaluated in the same manner as in Example 1. In Example 3, itaconic acid was used.

<Production of itaconic acid-modified PVA>
10 parts of vinyl acetate, 21 parts of methanol, 0.023 parts of dimethyl maleate, 0.204 parts of itaconic acid and 0.10% azobisisobutyronitrile with respect to vinyl acetate are charged into the polymerization vessel, and heated after purging with nitrogen. Then, the temperature was raised to the boiling point, and further, a mixture of 3.5 parts of vinyl acetate, 7.5 parts of methanol and 0.203 parts of dimethyl maleate was continuously added until the polymerization rate reached 75%, and polymerization was performed. The polymerization was stopped when the polymerization rate reached 90%. Subsequently, unpolymerized vinyl acetate is removed by a conventional method, and the resulting polymer is saponified with sodium hydroxide by a conventional method and dried to obtain an average polymerization degree of 400, a saponification degree of 39.0 mol%, and dimethyl maleate. A modified PVA having an absorbance of 0.9 at a wavelength of 270 nm of an aqueous solution of 1.0 mol%, 1.0 mol% of itaconic acid and a 0.2% aqueous solution and an unmodified PVA amount of 16% was obtained. <Analysis method>
The contents of dimethyl maleate and itaconic acid were measured by ¹ H-NMR and ¹³ C-NMR.

The dispersant of the present invention can be used for producing a vinyl chloride polymer.
The vinyl chloride resin produced by using the dispersant of the present invention has a high plasticizer absorption and can provide a molded product with little fish eye. Therefore, when the dispersant of the present invention is used, a vinyl chloride resin having excellent quality can be obtained.

The modified PVA can be easily cured with energy rays such as ultraviolet rays and electron beams by combining with a photoinitiator, a polymerizable monomer, etc., if necessary, and paints, inks, adhesives, printing plates Effectively used for etching resist, solder resist, vinyl chloride suspension polymerization dispersant, protective colloid agent in vinyl acetate emulsion polymerization, protective colloid agent in acrylic emulsion polymerization, protective colloid agent in styrene emulsion polymerization, etc. Can do.

Claims (10)

A modified polyvinyl alcohol having a saponification degree of 20 to 45% and an average polymerization degree of 100 to 1000 having a bond unit represented by the general formula (Chemical Formula 1) derived from dimethyl maleate or maleic anhydride in the molecular main chain.
(In formula, X1 and X2 represent a C1-C12 lower alkyl group, a hydrogen atom, or a metal salt. G represents the integer of 0-3. H represents the integer of 0-12. Y1. Represents a carboxylic acid, a carboxylic acid ester, a carboxylic acid metal salt or a hydrogen atom.) The modified polyvinyl alcohol according to claim 1, wherein the absorbance at 270 nm according to the ultraviolet absorption spectrum of 0.2 mass% of an aqueous solution, a methanol solution or a water-methanol mixed solution is 0.05 or more. The modified polyvinyl alcohol according to claim 1 or 2, wherein the peak top of the ultraviolet absorption spectrum derived from the unsaturated double bond represented by the general formula (Chemical Formula 2) is between 265 and 275 nm.
The modified polyvinyl alcohol according to any one of claims 1 to 3, wherein the content of unmodified polyvinyl alcohol is 25% or less. The modified polyvinyl alcohol as described in any one of Claims 1-4 formed by copolymerizing the monomer which has an anionic group in a side chain. The modified polyvinyl alcohol according to any one of claims 1 to 5, which is obtained by copolymerizing itaconic acid. The copolymer obtained by copolymerizing dimethyl maleate or maleic anhydride , a monomer having a vinyl ester unit, and a monomer copolymerizable with these monomers, and then saponifying the obtained copolymer. A method for producing a modified polyvinyl alcohol according to one item. The method for producing a modified polyvinyl alcohol according to claim 7, wherein the copolymerizable monomer is itaconic acid. In the process for producing a vinyl chloride polymer obtained by suspension polymerization of vinyl chloride or a mixture of monomers copolymerizable with vinyl chloride in an aqueous medium of a polymerization initiator and a dispersant, (1) The manufacturing method of the vinyl chloride polymer which uses together the modified polyvinyl alcohol as described in any one of 1-6, and dispersing agents other than (2) (1). (2) The method for producing a vinyl chloride polymer according to claim 10, wherein the dispersant other than (1) is polyvinyl alcohol having a saponification degree of 60 to 99% and an average polymerization degree of 1500 to 3000.