JPH0380052B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Field of Industrial Application The present invention relates to an aqueous dispersion composition having excellent coating film performance, comprising an ethylene-α,β-ethylenically unsaturated monocarboxylic acid copolymer or a salt thereof, and more specifically, relates to compositions that produce stable dispersions without the use of emulsifiers. It is known that an ethylene-α,β-ethylenically unsaturated monocarboxylic acid copolymer can be converted into a metal salt or ammonium salt to form an aqueous dispersion, and these aqueous dispersions can be used as paper coating agents, paper processing agents, and coating agents. It is widely used as adhesive, etc. (b) Prior Art Conventionally, two methods are known for producing an aqueous dispersion. One method is direct emulsion polymerization, and the other method is to disperse (post-disperse) a prepolymerized polymer in water. Generally, in either method, a large amount of emulsifier or protective colloid is used, and the emulsifier remains in the film formed from this aqueous dispersion, significantly reducing the physical properties of the film, especially water resistance, and adhesive performance. It has the disadvantage of causing As an attempt to improve this drawback, self-emulsifying aqueous dispersions that do not use emulsifiers are known. For example, a method in which ethylene and unsaturated carboxylic acid are copolymerized at high temperature and high pressure (Japanese Patent Publication No. 38-23494, etc.) is made into an emulsion by adding an alkali metal hydroxide or a base such as ammonium hydroxide (Japanese Patent Publication No. 38-23494, etc.). 42-275). However, it has the disadvantage that the acid used in producing the copolymer severely corrodes the reaction equipment, causing significant damage to the production equipment. On the other hand, a method for producing an ethylene-unsaturated carbon copolymer salt by hydrolyzing an ethylene-unsaturated carboxylic acid ester copolymer in the presence of water and an alkali metal hydroxide (Japanese Patent Publication No. 43-9558) ,
(Special Publication No. 33302/1973). however,
Even in these methods, since the reaction is carried out by heating to 180° C. or higher in the presence of a base such as an alkali metal, the reaction equipment is corroded and the equipment is severely damaged after long-term use. Also, please refer to Special Publication No. 46-42620 or Special Publication No.
In Publication No. 49-44578, ethylene-α, β
- A method has been proposed in which an ethylenically unsaturated carboxylic acid copolymer is dissolved in a mixture of water and a solvent, a base is reacted with the copolymer to disperse it in water, and the solvent is evaporated from the resulting dispersion. , solvent separation,
Not only is the recovery process complicated, but it is also economically expensive. Furthermore, Japanese Patent Publication No. 45-29909 describes a copolymer [(meth)]acrylic acid unit containing 10 to 50% by weight of ethylene and (meth)acrylic acid and optionally their esters. A process is also disclosed for latexizing .eta.]-value 0.0-1, measured at 100 DEG C. in cyclohexane, in the presence of a base at temperatures from 70 DEG to 180 DEG C. However, according to the experiments of the present inventors, the above-mentioned ethylene-(meth)acrylic acid or its ester copolymer (hereinafter simply referred to as ethylene copolymer) is also similar, but in general, the ethylene used is The copolymer has a high molecular weight of 7,000 to 40,000, which causes gelation and does not form a stable and good aqueous dispersion. On the other hand, in order to obtain a stable and good aqueous dispersion, methods of using an emulsifier or adding an inorganic salt or an organic salt to a high viscosity polymer aqueous solution to lower the viscosity (Japanese Patent Application Laid-open No. 1983-61249) , or a method using a low molecular weight ethylene copolymer (Japanese Patent Publication No. 55-6641), or by thermally decomposing an ethylene-alkyl (meth)acrylate copolymer to reduce the molecular weight and then adding ammonia or amines. 50-100
It can be produced by a method of reacting at a temperature of 100°C (Japanese Unexamined Patent Publication No. 53-59789), but in any of these methods, an aqueous dispersion with excellent coating performance superior to that of polyethylene cannot be produced. No. (c) Problems to be Solved by the Invention In view of the above points, the present inventors have conducted intensive research and have completed the present invention. The purpose of the present invention is to use a polymer that maintains low viscosity even at high resin concentrations and has superior polyethylene properties, resulting in excellent coating film performance such as strength, water resistance, and heat resistance, and a simple method. The present invention provides an aqueous dispersion composition which is stable and has good self-emulsifying properties. (d) Means for solving the problems The present invention provides (A) relatively high molecular weight ethylene-α,
A β-ethylenically unsaturated monocarboxylic acid ester copolymer is heat-degraded in the presence of water or steam in an inert atmosphere at a temperature of 200 to 500°C, and has a viscosity average molecular weight of 7,000 to 30,000. and a degraded product containing 0.5 to 3 mol% of carboxylic acid units or a completely or partially neutralized product of the degraded product containing 10 to 90% of carboxylic acid units.
weight% and (B) a carboxyl group-containing polymer with a viscosity average molecular weight of 500 to 5000 and an acid value of 30 or more, or a completely or partially neutralized product of the polymer, 90 to 10%.
The present invention provides an aqueous dispersion composition comprising at least two components (% by weight) dispersed in water. Ethylene-α, β-, the raw material used in the present invention
Ethylenically unsaturated monocarboxylic acid ester copolymer (hereinafter simply referred to as ethylene copolymer) is
Methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate,
From the group consisting of esters of acrylic acid or methacrylic acid with alcohols having 1 to 12 carbon atoms, such as isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, etc. 3 selected comonomer units
~50% by weight, with a viscosity average molecular weight of
A range of 30,000 to 100,000 is preferred. Component (A) of the present invention uses the relatively high molecular weight ethylene copolymer described above, and is heated in an inert atmosphere in the presence of water or steam at a temperature in the range of 200 to 500°C to reduce the viscosity. A degraded product having an average molecular weight in the range of 7000 to 30000, preferably 10000 to 17000, and containing 0.5 to 3 mol% of carboxylic acid units, preferably 0.7 to 2.5 mol%, or in whole or in part of the degraded product. It consists of a
It is possible to arbitrarily reduce the molecular weight of a relatively high molecular weight ethylene copolymer, and it is possible to reduce the molecular weight of an ethylene copolymer with a relatively high molecular weight.
Not only can it be produced more easily and economically at a lower cost than in the Japanese Patent Publication (No. 3), but it also has the characteristic that low viscosity is maintained even at high resin concentrations due to the residual ester moieties. On the other hand, in Japanese Patent Publication No. 46-21643, ethylene
A method is disclosed for obtaining an ethylene-acrylic acid copolymer by heating a copolymer consisting of acrylic acid isopropyl ester to a high temperature in the presence of steam or ammonium until all ester groups are hydrolyzed. . However, this method does not achieve the important objective of the present invention, which is to arbitrarily reduce the molecular weight of the raw material copolymer. The inert atmosphere as used in the present invention is not particularly limited, but it is appropriate to pass an inert gas such as nitrogen, carbon dioxide, argon, or helium through the reaction system to completely exclude air. Among them, it is preferable to use nitrogen. Furthermore, the temperature and pressure when carrying out the present invention depend on the properties of the raw materials used, that is, the average molecular weight of the ethylene copolymer, the ester content, the degree of molecular weight reduction, and the types of raw materials used. Depends on factors such as the amount of water, but typically the temperature is 200~
The temperature is 500° C. and the pressure is 5 to 500 kg/cm ² , and the reaction time is in the range of 1 to 10 hours, preferably 2 to 6 hours. If the above temperature is less than 200℃, it is not possible to lower the molecular weight of the raw resin, and if the temperature exceeds 500℃, the ester in the copolymer will volatilize and a decarboxylation reaction will occur, resulting in severe decomposition. I don't like it. The heat-degraded product obtained by the above heat-degradation conditions is an ethylene-carboxylic acid binary copolymer and/or an ethylene-carboxylic acid-alkyl carboxylate terpolymer whose molecular weight has been arbitrarily reduced. The viscosity average molecular weight is in the range of 7,000 to 30,000, preferably 10,000 to 17,000, and contains 0.5 to 3 mol% of carboxylic acid units, preferably 0.7 to 2.5 mol%. As mentioned above, when the viscosity average molecular weight is less than 7,000 and the carboxylic acid unit exceeds 3 mol%, the coating film performance such as strength, water resistance, and heat resistance decreases, and when the viscosity average molecular weight exceeds 30,000 and If the carboxylic acid unit content is less than 0.5 mol%, it is difficult to obtain a good aqueous dispersion. The above viscosity average molecular weight was determined from the following formula using the intrinsic viscosity [η] of decalin solvent at a temperature of 135°C. [η]=KM (K=14.3×10 ⁻⁵ (dl/g), α=0.82) In the present invention, it is also possible to completely or partially neutralize the degraded product. The neutralizing agent may be an alkali metal compound, an alkaline earth metal compound, an inorganic basic compound such as ammonia, or a compound showing basicity in water such as an organic basic compound. More specifically, for example, lithium hydroxide,
Potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, barium hydroxide,
Strontium hydroxide; lithium oxide, potassium oxide, sodium oxide, calcium oxide, magnesium oxide, strontium oxide, barium oxide; potassium carbonate, sodium carbonate, calcium carbonate, magnesium carbonate, potassium bicarbonate, sodium bicarbonate, calcium bicarbonate, Magnesium carbonate; sodium formate, potassium acetate, sodium acetate, sodium propionate, zinc acetate,
Inorganic basic compounds such as magnesium acetate, ammonium hydroxide, and ammonia, or monoalkylamines such as methylamine, ethylamine, and propylamine, secondary and tertiary amines such as dimethylamine, diethylamine, trimethylamine, and triethylamine. , ethanolamine,
Included are monoalkanolamines such as isopropanolamine, polyalkanolamines such as dimethylethanolamine, monocycloalkylamines such as cyclohexylamine, and monocycloalkanolamines such as cyclohexanolamine. Furthermore, morpholine, pyridine, etc. are also suitably used as neutralizing agents. Neutralization can be achieved by melting the degraded product and kneading it with the above-mentioned alkali metals, bases such as amines, etc. at a predetermined temperature, and it may also be carried out in the same equipment after the thermal degradation. Take out the degraded product,
You can neutralize it later. Neutralization may be complete neutralization, but in the case of partial neutralization, at least
It is preferable that the degree of neutralization is 10% or more. Component (B) of the present invention has a viscosity average molecular weight of 500 to 5000,
It is preferably a carboxyl group-containing polymer in the range of 2,000 to 5,000 and an acid value of 30 or more, preferably 50 or more, or a completely or partially neutralized product of the polymer. Examples of these include (1) honey; Natural waxes such as wax, carnauba wax, wood wax, and montan wax, and synthetic waxes such as paraffin wax, polyethylene wax, α-olefin wax, and fissure tropism wax, as well as unsaturated carboxylic acids such as maleic acid. By emulsification or solution polymerization using modified waxes with added acids or metal salts thereof, (2) radicals (including telomerization), olefins and α,β-ethylenic inorganics such as acrylic acid, methacrylic acid, maleic acid, etc. Examples include copolymers with saturated carboxylic acids or metal salts thereof, or low molecular weight ethylene copolymers obtained by thermally degrading relatively high molecular weight ethylene copolymers similar to component (3) (A), or metal salts thereof. However, the method (3) is preferred because it allows the molecular weight to be lowered as desired and is economically advantageous. If the above viscosity average molecular weight is less than 500, the strength of the coating film
Coating film performance such as water resistance deteriorates, and when the molecular weight exceeds 5,000, the effect of improving dispersibility is small. Similarly, when the acid value is less than 30, no effect of improving dispersibility is observed. The composition of the present invention has at least 10 to 90% of the above component (A).
% by weight, preferably 50-90% by weight and component (B) 90-10
% by weight, preferably in the range of 10 to 50% by weight. If the content of component (A) is less than 10% by weight, there is a concern that the strength, water resistance, and heat resistance of the coating film will decrease, and if it exceeds 90% by weight, the dispersibility of the emulsion will deteriorate. The method of aqueous dispersion of the compositions of the invention is carried out at customary temperatures, i.e. 100-200°C, preferably 120-200°C.
It is carried out by adding component (A), component (B), base and water into an autoclave at a temperature of 160°C and stirring. The order of addition of the above (A) component and (B) component is not particularly limited. For example, (1) predetermined amounts of the heat-degraded product of the (A) component and the heat-degraded product of the (B) component are placed in an autoclave. A method of injecting an aqueous solution of sodium hydroxide after melting and stirring at a predetermined temperature to create an aqueous dispersion. (2) A completely or partially neutralized product of the thermally degraded product of component (A) is previously melted in an autoclave. (3) A method of injecting water and a thermally degraded product of component (B) or a completely or partially neutralized product thereof and stirring at a predetermined temperature to obtain an aqueous dispersion.
Any method may be used, such as heating and melting component (B) in advance, adding water or an aqueous alkaline solution and component (A), stirring at a predetermined temperature, and dispersing the mixture in an aqueous manner. A solvent may also be present. Further, in order to stabilize the aqueous dispersion, it is desirable to adjust the pH of the aqueous solution to a range of 7 to 11. The aqueous dispersion thus obtained has a maximum particle size of
It is possible to obtain a good aqueous dispersion with a solid content of 20μ or less and a solids concentration in the range of 10 to 50% by weight. The aqueous dispersion composition of the present invention comprises the above component (A) and (B)
The main component is a water-soluble amino resin or a water-soluble epoxy resin, such as a water-soluble melamine resin or a water-soluble benzoguanamine resin, if necessary, to improve the coating performance.
Or polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyethylene oxide, polyacrylamide, polyacrylic acid, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, glue, casein to improve the stability of the dispersion and adjust the viscosity. , organic thickeners such as dextrin, or inorganic thickeners such as silicon dioxide, activated clay, and bentonite, nonionic surfactants, and anionic surfactants to stabilize the aqueous dispersion or improve the solid content concentration. Surfactants such as anti-rust agents, anti-mold agents, ultraviolet absorbers, heat stabilizers, anti-foaming agents, foaming agents, pigments such as titanium white, red iron, phthalocyanine, carbon black, permanent yellow, etc.
Even if it contains fillers such as calcium carbonate, magnesium carbonate, barium carbonate, talc, aluminum hydroxide, calcium sulfate, kaolin, mica, asbestos, mica, calcium silicate, etc., to the extent that the purpose of the present invention is not impaired. good. (E) Effect In the present invention, relatively high molecular weight ethylene-α,
A low molecular weight carboxyl group-containing polymer with an acid value of 30 or more that can be easily produced from β-ethylenically unsaturated monocarboxylic acid copolymers or their completely or partially neutralized products without problems such as corrosion. By mixing in a specific ratio, a good aqueous dispersion can be obtained without using an emulsifier or the like. Further, the coating film of the aqueous dispersion becomes a polyethylene coating film, and film properties such as water resistance and coating film hardness are improved. (F) Examples The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these Examples unless it departs from the gist of the present invention. Example 1 Ethylene-ethyl acrylate copolymer (hereinafter simply referred to as EEA) as a raw material (EA content 18% by weight,
Viscosity average molecular weight 36000) 1.5Kg and 1000ml of water 3.8
The mixture was charged into an autoclave and thermally degraded under a nitrogen atmosphere at a temperature of 350° C. and a pressure of 200 kg/cm ² for 1 hour to obtain a thermally degraded product having a viscosity average molecular weight of 12,000 and a carboxylic acid unit content of 2.1 mol %. The heat-reduced product was taken out and heated to 170° C. in a kneader to heat-melt it, and a saturated aqueous sodium hydroxide solution was added to obtain a completely neutralized component (A). On the other hand, 1.5 kg of the above raw material EEA and 1000 ml of water were put into an autoclave, and thermally degraded in a nitrogen atmosphere at a temperature of 360°C for 4 hours, and the viscosity average molecular weight was reduced.
4000, and a thermally degraded product with an acid value of 70 was obtained. The heat-reduced product was taken out and heated to 170° C. in a kneader to heat-melt it, and a saturated aqueous sodium hydroxide solution was added to obtain a completely neutralized component (B). 25 parts of a composition prepared by mixing 50% by weight of component (A) and 50% by weight of component (B) above and 75 parts of water were poured into an autoclave, stirred at a temperature of 140°C for 2 hours while maintaining the pH at 11, An aqueous dispersion was obtained, and the stability and film properties of the aqueous dispersion were measured, and the results are shown in Table 1. Examples 2 to 5 Components (A) and (B) used in Example 1 were used with various A/B mixing ratios, and emulsions were formed in the same manner as in Example 1. The evaluation results are shown in Table 1. Indicated. Example 6 Composition 25 in which unneutralized heat-degraded products of component (A) and component (B) of Example 1 were mixed at 50% by weight each.
and 75 parts of an aqueous sodium hydroxide solution were charged into an autoclave and stirred at a temperature of 140°C for 2 hours to obtain an aqueous dispersion, which was evaluated in the same manner as in Example 1. The results are shown in Table 1. Example 7 The same procedure as in Example 1 was carried out except that N,N'-dimethylethanolamine (abbreviated as DMEA) was used instead of sodium hydroxide as the base in Example 1, and the results are shown in Table 1. . Comparative Example 1 An attempt was made to obtain an aqueous dispersion in the same manner as in Example 1 using only the component (A) used in Example 1, but it turned into a gel. Comparative Example 2 An aqueous dispersion was obtained in the same manner as in Example 1 using only the component (B) used in Example 1, and the results of its evaluation are shown in Table 1. As a result, the coating film hardness was low and the water drop test was also poor. Comparative Example 3 Using the completely neutralized product of the thermal degradation product of Example 1 as the (A) component, and containing 5% by weight of EA as the (B) component.
Heat degraded EEA in 1000 ml of water at 360℃ for 4 hours, and use a heat-degraded product with an acid value of 20 and a viscosity average molecular weight of 4000, completely neutralized with sodium hydroxide to make 50% by weight each. Although the mixture was mixed in a similar manner and aqueous dispersion was carried out in the same manner as in Example 1, coarse particles remained and a uniform dispersion was not obtained. The results are shown in Table 1. Comparative Example 5 To 20 parts of component (A) used in Example 1, 1 part of Emal 0 (anionic surfactant) as a surfactant and water were added.
Pour 80 parts into an autoclave at a temperature of 180℃.
Although the mixture was stirred for 3 to 4 hours to form an aqueous dispersion, a uniform dispersion was not obtained. The results are shown in Table 1. Comparative Example 6 17 parts by weight of component (A) used in Example 1 and oleic acid
2.9 parts by weight were mixed in an autoclave, and an aqueous solution of 3.0 parts by weight of morpholine and 0.3 parts by weight of sodium hydroxide dissolved in 80 parts by weight of water was added.
The mixture was stirred at a temperature of 160° C. for 2 hours to form an aqueous dispersion, and evaluated in the same manner as in Example 1. The results are shown in Table 1. Comparative Examples 7-8 For reference, a commercially available emulsion, “Movinyl”
303”, “Movinyl 803” (trade name, Hoechst Synthetic
Table 1 shows the results of coating film hardness and water droplet tests conducted using a coating film manufactured by Co., Ltd.). Comparative Example 4 Raw material EEA containing 5% by weight of EA was thermally decomposed in the same manner as in Example 1 to obtain a thermally degraded product containing 0.3 mol% of carboxylic acid units and a viscosity average molecular weight of 12,000.
Table 1 shows the results of mixing 50% by weight of the thermally degraded product of component (B) and evaluating it in the same manner as in Example 1. The evaluation method and test method for the aqueous dispersion are as follows. Evaluation () Condition of aqueous dispersion ◎ ○ △ × (a) Appearance judgment...Aqueous Fine Rough Particle condition of gelled dispersion (b) Viscosity...Low Medium High Gelled by appearance observation (c) Storage stability ...Viscosity change when left at room temperature Low Medium High Gelling () Coating film hardness Depends on Sword Rocker. () Water drop test Compliant with JISK-6828

【table】

[Table] (G) Effects of the invention As mentioned above, the aqueous dispersion composition of the present invention has
Without using conventional emulsifiers or acid value replenishers such as oleic acid, we can provide a good aqueous dispersion with excellent polyethylene properties, and can be used in paints, adhesives, paper, metals, glass, wood, etc. Surface coating agents for various base materials such as plastics, paper reinforcing agents, paper sizing agents, ceramic binders, fiber sizing agents, waterproofing agents, vinyl acetate emulsions, acrylic emulsions, vinyldene chloride emulsions,
It is utilized in many fields, including the ability to improve the coating of synthetic resin emulsions such as styrene-butazine rubber emulsions, ethylene-vinyl acetate copolymers, and ethylene-vinyl chloride copolymers.

Claims (1)

[Scope of Claims] 1 (A) A relatively high molecular weight ethylene-α,β-ethylenically unsaturated monocarboxylic acid ester copolymer is heated in an inert atmosphere in the presence of water or steam at a temperature of 200 to 200°C. A degraded product obtained by heating at 500°C and having a viscosity average molecular weight of 7,000 to 30,000 and containing 0.5 to 3 mol% of carboxylic acid units or a completely or partially neutralized product of the degraded product is 90%
~10% by weight, and (B) a viscosity average molecular weight of 500 to 5000 and an acid value of
An aqueous dispersion composition comprising at least two components, 10 to 90% by weight of a polymer containing 30 or more carboxyl groups or a completely or partially neutralized product of the polymer, dispersed in water. 2. The aqueous dispersion composition according to claim 1, wherein the ethylene-α,β-ethylenically unsaturated monocarboxylic acid ester copolymer is an ethylene-ethyl acrylate copolymer. . 3 The carboxyl group-containing polymer of component (B) is
A relatively high molecular weight ethylene-α,β-ethylenically unsaturated carboxylic acid ester copolymer is heated in an inert atmosphere in the presence of water or steam at a temperature of 200 to 200°C.
Claim 1 or 2, characterized in that the product is a degraded product obtained by heating at a temperature of 500°C.
The aqueous dispersion composition described in . 4. The aqueous dispersion composition according to claim 3, wherein the ethylene-α,β-ethylenically unsaturated carboxylic acid ester copolymer of the component (B) is ethylene-ethyl acrylate. thing.