JPS58191702A - Preparation of modified polyvinyl acetal - Google Patents

Abstract

PURPOSE:To prepare the titled compound exhibiting excellent dispersing activity in a solvent, by acetalizing a PVA solution of a carboxylic acid-modified PVA with an aldehyde compound in the presence of a nonionic surface active agent and a mineral acid. CONSTITUTION:A solution or dispersion composed of 50-98pts.wt. of a PVA having an average polymerization degree of 200-5,000 and 2-50pts.wt. of a carboxylic acid-modified PVA is added with an aldehyde compound and made to react with each other in the presence of 0.01-2wt% of a nonionic surface active agent having an HLB value of 10-19 (e.g. polyoxyethylene lauryl ether) and 1.0-50wt% (based on the solution or dispersion) of a mineral acid at <=50 deg.C under stirring to effect the acetalization of the PVA.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a modified polyvinyl acetal that is solvent soluble and exhibits excellent dispersant action in a solvent.

The method of the present invention involves adding and mixing an aldehyde compound to a polyvinyl alcohol solution or dispersion containing carboxylic acid-modified polyvinyl alcohol in the presence of a nonionic surfactant and a mineral acid. , characterized in that the above-mentioned polyvinyl alcohol is acetalized.

The polyvinyl alcohol used in the present invention suitably has an average degree of polymerization of about 200 to 5,000, and its saponification degree may be as long as it exhibits the properties generally referred to as polyvinyl alcohol.

Furthermore, the carboxylic acid-modified polyvinyl alcohol acts as a dispersant for the reaction system, keeps the reaction system homogeneous, and is itself acetalized, thereby improving the function of the product as a dispersant. Such carboxylic acid-modified polyvinyl alcohol is generally a water-soluble resin obtained by saponifying a copolymer of vinyl acetate and an unsaturated carboxylic acid, an unsaturated carboxylic acid ester, an unsaturated dicarboxylic acid ester, or an unsaturated dicarboxylic acid anhydride. Representative examples of the above unsaturated carboxylic acids include acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, maleic ester, fumaric acid ester A/, maleic anhydride, and itaconic ester.

The proportion of polyvinyl alcohol and carboxylic acid-modified polyvinyl alcohol in combination is not particularly limited, but it is usually preferably 2 to 50 parts by weight of carboxylic acid-modified polyvinyl alcohol to 50 to 98 parts by weight of polyvinyl alcohol.

Polyvinyl alcohol and carboxylic acid-modified polyvinyl alcohol are available in aqueous solutions and organic solvent solutions.

The reaction is carried out in the form of a water-containing organic solvent solution or a dispersion in an organic solvent or a water-containing organic solvent. As an organic solvent,
Although toluene and alcohol 1fAV are used, it is generally preferred to use water or a water-containing organic solvent as the liquid medium.

Note that mineral acids act as catalysts, such as sulfuric acid,
Hydrochloric acid, nitric acid, etc. are used. The amount of mineral acid used is approximately 1.0 to 504% by weight of polyvinyl alcohol and carboxylic acid-modified polyvinyl alcohol Ji(7).

Further, the aldehyde compounds used in the present invention include formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, heptylaldehyde, benzaldehyde, etc., and these may be used alone or in a mixture of two or more. Can be used.

The aldehyde compound is preferably used in an amount of from equimole to b moles per vinyl alcohol unit of polyvinyl alcohol and carboxylic acid-modified polyvinyl alcohol.

In the present invention, first, a solution or dispersion of polyvinyl alcohol and carboxylic acid-modified polyvinyl alcohol is prepared, a nonionic surfactant and a mineral acid are added thereto, and after stirring,
The aldehyde compound is added to this liquid at a relatively low temperature, eg, below 20'C. Preferably, the aldehyde compound is mixed dropwise.

After addition of the aldehyde compound, the reaction system was heated at 20°C.
After stirring for 1 hour at a temperature below 20-50°C, especially 30-4
Preferably, stirring is continued for 1 to 2 hours at 0°C.

In the method of the present invention, there is no need to carry out the reaction at high temperatures as is generally used, and when water is used as a solvent, an extremely fine powdery reaction product is obtained, and even when an organic solvent is used, a homogeneous reaction product is obtained. A reaction product is obtained.

When water is used as a solvent, add an alkali or potassium substance such as caustic alkali, alkali carbonate, or aqueous ammonia to the reaction system in an amount corresponding to the mineral acid used as a catalyst to neutralize the reaction system. The reaction product is filtered, washed with water and dried to obtain a product.

In addition, when a combined organic solvent or an organic solvent is used, after neutralizing the reaction system as described above, the reaction system is poured into vigorously stirred water, and the precipitated reaction products and products are filtered out. Wash with water and dry, or pour the reaction system directly into vigorously stirred water,
Thereafter, this aqueous mixture is neutralized, and the precipitated reaction product is filtered off, washed with water, and dried to obtain a product.

The products obtained by the present invention are highly dispersible and can be obtained in fine powder form, with excellent homogeneous solubility in organic solvents such as evaporated ethanol, toluene, methyl ethyl ketone, styrene monomer, and cyclohexanone. inorganic compounds such as alumina,
Useful as a dispersant for dispersing metal powders, magnetic iron oxides, silicon nitride, bentonite, kaolin, silicon and carbide, organic or inorganic pigments, pesticides, etc.

In addition, in the present invention, a small amount (for example, 0.0
1 to 2% by weight) of a nonionic surfactant is added, and as this surfactant, polyethylene glycol alkyl ether or hapolyethylene glycol alkyl phenyl ether of HLBIO-19 is preferably used. By adding a nonionic surfactant, the reaction system is kept more homogeneous and the reaction becomes smoother.

Next, examples of the present invention will be shown. In the examples, % indicates 9% by weight unless otherwise specified.

Example (1) Maleic anhydride with an average molecular weight of 53,100 is added to 90 parts of polyvinyl alcohol with a degree of saponification of 98 mol% and a degree of polymerization of 10 oo.
9 to which 5.3 parts of vinyl alcohol maleic acid copolymer resin obtained by saponifying lead acid vinyl copolymer resin
00 tel of water and heated at 80-90'C for 1 hour to dissolve. After complete dissolution, the nonionic activator polyoxyethylene lauryl ether (HL, B12.O)
1 g was added, stirred, and then cooled to 15°C. 37 to this
Add 50 g of % hydrochloric acid and mix thoroughly, then add 78 parts of n-butyraldehyde dropwise and mix at 15-20°C. After completing the dropwise addition in 30 minutes, stir at the same temperature for 1 hour, and then reduce the reaction system to 30-35°C. The temperature was raised to °C and stirred at the same temperature for 2 hours. Next, the reaction system was cooled to 20'C or less, and added with 20% sodium carbonate.
7.9 was added in several portions to neutralize the reaction system 1 acid.

After filtering the precipitated fine powder, washing with water and dehydrating it,
It was dried under reduced pressure at ~600C.

The particle size of the product thus obtained was such that 90% passed through a 60 mesh, and the degree of butyralization was 66 mol%. The product also contains toluene/ethanol/l/l:
It was completely dissolved in the mixed solvent, and the viscosity of the 10% solution at 20°C was '10Ocps.

Example (2) 10% hydrated isopropyl alcohol 9000, saponification degree 97 mol%, polymerization degree 100o polyvinyl alcohol
A mixture of 90 parts of A/90 parts and 9 parts of a vinyl alcohol maleic acid copolymer resin obtained by saponifying a vinyl acetate maleic anhydride copolymer resin having an average molecular weight of 53,200 was added, and then 40.9 parts of 37% hydrochloric acid and hyphorioxy Ethylene nonyl phenyl ether ()-ILB 13.0 ) 1 fi
was added, and the uniformly mixed solution was cooled to 13°C, and 79 g of isobutyraldehyde was added dropwise while stirring.

After the addition was completed, the reaction system was stirred at 20'C for 30 minutes, and then
By heating to 40°C and stirring for 1 hour, the reaction system became a completely clear solution.

The reaction system was cooled to 15°C while stirring, and added with sodium bicarbonate-3
4 J/ was added in several portions to neutralize the reaction system. Next 1
Water 20001/ cooled to 0°C was vigorously stirred, and the reaction system was poured into it. The precipitated powder was filtered, washed with water, and then dried with hot air at 40'C. The degree of butyralization of the resin was 69 mol%, ivy. This resin was completely dissolved in styrene monomer or toluene. Toluene ethanol (
The viscosity of a 10% solution using a 1:l) mixed solvent at 20°C was 85.0 cps.

Example (3) 90 parts of polyvinyl alcohol with a saponification degree of 99 mol% and a degree of polymerization of 900, 18 parts of a vinyl alcohol acrylic acid copolymer resin with an average molecular weight of 53,100, and polyoxyethylene decyl ether (HLB 14°0) 2 in 10,100 O of water.
g and stirred at 80°C for 1 hour to completely dissolve.

The solution was then cooled to 15°C and 37% hydrochloric acid co
After adding 88 g of n-butyraldehyde and stirring thoroughly,
portions were mixed dropwise.

After completion of the dropwise addition, the reaction system was heated to 30-35'C, stirred at the same temperature for 2 hours, cooled to below 15°C, and sodium bicarbonate-349 was added several times to neutralize the reaction system. The precipitated fine powder was filtered, washed with water, dehydrated, and then dried with stirring by blowing hot air at 60°C. The particle size of the product obtained was such that 86% passed a 60 mesh. The degree of butyralization of the product is 6
At 5%, it is completely dissolved in a mixed solvent of toluene and methyl ethyl ketone (1:1), and the viscosity of a 10% solution at 20°C is 7.
It was 0 Cps.

Example (4) A mixture of 80 parts of polyvinyl alcohol with a degree of saponification of 89% and a degree of polymerization of 1200 and 20 parts of a vinyl alcohol maleic acid copolymer resin with an average molecular weight of 58176 was added to 20% hydrated isopropanol 1000fi and stirred. Polyoxyethylene tridecyl ether A/(HLB 14°0) 29 and sulfuric acid 209 were added to this, and the mixture was cooled to 10°C. Isobutyraldehyde 859 was added dropwise to the mixture, and after completing the addition in about 15 minutes, the temperature was raised to 40°C and stirred for 2 hours. The reaction system became a transparent liquid. The reaction system was then cooled to 15°C and neutralized by adding 25.9 g of 28% aqueous ammonia, and poured into 2 ooozl of water cooled to 100 C with vigorous stirring.

The generated precipitate was filtered, washed with water, dehydrated, and dried under reduced pressure at 60°C. Powdered product resin is transparently dissolved in toluene.
,, The viscosity of 2o0c of a 10% solution using toluene/cyclohexanone (1:1) mixed solvent is 100cI
) S, and the degree of butyralization was 69 mol%.

Example (5) Polyvinyl alcohol-A with a degree of saponification of 98% and a degree of polymerization of 500
/94.5 parts of vinyl alcohol acrylic acid co-polymer resin with an average molecular weight of 53,100 was mixed with 800 parts of water.
After completely dissolving the solution, the solution was cooled to 15°C, and 35p of 37% hydrochloric acid was added to the solution, followed by thorough stirring.

First, polyoxyethylene octylphenyl ether iv ('HLBxs, o ) z9 was added to the solution, and 90 g of isobutyraldehyde was added dropwise to the solution using a stirring knife.

After completion of the dropwise addition, the reaction system was stirred at 15 to 20 °C for 1 hour,
The temperature was raised to 30-35°C and stirred at the same temperature for 2 hours. The mixture was cooled to below 20°C, and 30 g of sodium bicarbonate was added several times to neutralize the reaction system. The precipitated powder was filtered, washed with water, and then dried with air at 600C with stirring.

80% of the resin thus obtained passes through a 50 mesh, is completely dissolved in a mixed solvent of toluene ethanol-A/(1:1), and the viscosity of a 30% solution of 2000 is 20CI)S. Met.

Example (6) (1) A, modified butyral resin obtained in Example (2) and B
The dispersibility of alumina oxide in a toluene-n-butanol (1:1)/Jt mixed solvent was compared for polyvinyl butyral resin obtained from polyvinyl alcohol having a degree of saponification of 98 mol% and a degree of polymerization of 1000.

40% alumina oxide, toluene/n-phytano A/
(1: l) Mixed solvent 58% with wood A or 82%
% was added to the dissolved material, placed in a 200III cylinder with a stopper, shaken for 5 minutes in a shaker, and then left to stand for 60 minutes, and then the height of the opaque layer was read.

A, 95gt B, 55m1 (2) Example (C1 modified butyral resin obtained in 5J).

γ-p of polyvinyl butyral resin obtained from polyvinyl alcohol with a degree of saponification of 98 mol% and a degree of polymerization of 500 in a mixed solvent of toluene and methyl ethyl ketone (1:l).
The dispersibility of e 203 (MX-450 manufactured by Toda Kogyo Co., Ltd.) was compared.

γ-Fe2O3 40%, toluene/methyl ethyl ketone mixed solvent 5B%, resin C1 or l), 2% dissolved, put in a 200 yst cylinder with a stopper, shaken for 10 minutes with a shaker, and left to stand for 10 minutes. Read the height of the opaque layer.

C, 80 g/D, 32 recommended l Example (maleic anhydride with an average molecular weight of 53,100 in 95 parts of polyvinyl alcohol with a degree of saponification of 98 mol% and a degree of polymerization of 1000)
Adding 5 parts of vinyl alcohol maleic acid copolymer resin obtained by saponifying vinyl acetate copolymer resin to 900
In addition to the in-10 panol of d, polyoxyethylene nonylphenyl ether (HLB17.O) 5 f
1, stirred, cooled to 15°C, and added 37% hydrochloric acid 40°C.
Add 50 g of isobutyraldehyde and mix thoroughly.
After stirring at 15-20°C for 30 minutes, another 35 parts of isobutyraldehyde was added dropwise. After stirring at 15-20°C for 1 hour, the temperature was raised to 30-35°C and stirred for 2 hours.

Then, the reaction system was cooled to below 15°C and added with sodium bicarbonate-3.
4II was added in several portions to neutralize the reaction system. then 10
2000 ml of water cooled to 0.00 mL was vigorously stirred, and the reaction system was pressurized therein. 7JI-
The degree of isobutyralization of the resin obtained by filtering, washing with water, and drying with hot air at 50 to 60°C was 71 mol%. This resin was completely dissolved in toluene and styrene monomer.

It also completely dissolves in toluene:ethanol (1: l)/l solvent, and the viscosity of a 10% solution at 20 °C is 50 Cp.
It was s.

Patent applicant: Daiichi Kogyo Seiyaku Co., Ltd.

Claims (4)

[Claims] (1) Add and mix an aldehyde compound to a polyvinyl alcohol solution or dispersion containing carboxylic acid-modified polyvinyl alcohol in the presence of a nonionic surfactant and a mineral acid, and mix with the above-mentioned acid-modified polyvinyl alcohol. A method for producing modified polyvinyl acetal, which comprises simultaneously acetalizing the polyvinyl alcohol. (2) To 50 to 98 parts by weight of the polyvinyl μ alcohol, to the acid-modified polyvinyl alcohol/L/2 to
Process according to claim 1, characterized in that 50 parts by weight are used. (3) The mineral acid is 1.0 to 5 relative to the polyvinyl alcohol and carboxylic acid-modified polyvinyl alcohol.
3. The manufacturing method according to claim 1 or 2, characterized in that it is used in a proportion of 0M %. (4) The production method according to any one of claims 1 to 3, wherein the acetalization reaction is carried out at 50'C or less.