JPS5853940A - Preparation of hydrosol - Google Patents

Abstract

PURPOSE:To prepare a hydrosol capable of forming a coating film or formed article having excellent water resistance and high physical properties, by neutralizing a specific high-molecular copolymer synthesized in the absence of solvent or in the presence of a small amount of solvent, and dispersing the neutralized product in water by phase inversion. CONSTITUTION:A copolymer having a weight-average molecular weight of 10<4>- 10<6> and composed of 1-20wt% unsaturated monomer having acidic group and 99-80% other unsaturated monomer copolymerizable therewith, is synthesized in the absence of solvent or in the presence of a small amount of solvent. An alkali or an alkaline aqueous solution is added to the copolymer to neutralize a part of or the whole acidic groups in said copolymer, and the product is subjected to the phase inversion by adding water. A hydrosol of the copolymer having an average particle diameter of 0.01-0.1mum and dispersed stably in water can be obtained by this process. The solvent is preferably methanol, etc., and its amount is <=20%. The monomer having acidic group is e.g. acrylic acid, etc., and the copolymerizable monomer is an acrylic acid ester having 3-10C alkyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides hydrosil particles with a particle size of 0.01 to 0.1μ.
A new method for producing a dispersion in which polymer particles of m are stably dispersed in water, and is characterized by hydrosilating a relatively high molecular weight polymer synthesized without a solvent or in the presence of a small amount of solvent. Concerning a new manufacturing method.

Conventionally, methods for producing hydrosil include polymer particles having a carboxyl group (particle size of approximately 0.0 .3~0
The so-called strippable method is generally used, in which the surface of particles (7 μm) is scraped off while stirring at high speed using an alkali such as caustic potash, caustic soda, or ammonium hydroxide to make fine particles with a particle size of approximately 0.01 to 0.1 μm. It has been adopted.

However, according to the conventional method described in item 1, emulsifiers are mixed into the hydrosil, which deteriorates the il+il aqueous properties of coating films and other molded products obtained therefrom. Further, there is a limit to the molecular weight of a polymer that can be hydrosilated, and generally, when the weight average molecular weight is 104 (10,000) or more, hydrosilation becomes difficult. For this reason, there was a natural limit in terms of application to various uses, and applications could only be developed mainly in the paint field and paper size processing field.

This invention was made with the aim of avoiding the above-mentioned conventional drawbacks, and its gist is that unsaturated monomers 1- Weight average molecular weight 10 consisting of 20% by weight and 99 to 80% by weight of other unsaturated monomers copolymerizable therewith.
Synthesize a copolymer of 4 to 106, add an alkali or aqueous alkali solution to neutralize part or all of the acidic groups in the copolymer molecule, and further add water to phase invert the above. A method for producing hydrosil, characterized by obtaining hydrosil in which a copolymer is stably dispersed in water with an average particle diameter in the range of 001 to 0.1 μm.

That is, the inventors compared the molecular weight of a specific copolymer with acidic groups obtained by bulk polymerization or solution polymerization using a small amount of solvent, rather than using a polymer emulsion as in the past. After neutralizing the copolymer with an alkali or alkaline aqueous solution, the above copolymer has an average particle size in the range of 0.01 to 0.1 μm by adding water and inverting the phase. We succeeded in obtaining hydrosil stably dispersed in water.

The hydrosil according to the present invention obtained in this way is
When made into coatings or other molded products, it exhibits a much improved 111iJ aqueous property compared to conventional hydrosils, and since the molecular weight of the polymer is relatively high, it also has good physical properties. It exhibits the same excellent performance as coating films formed from general organic solvent solutions. For this reason, the range of applications is wider than that of conventional hydrosils, from paint and paper to noise treatment agents, as well as adhesives, adhesives, etc.
It can be extremely effectively applied to various fields such as overcoating agents, exterior materials, interior coatings, packaging materials, and films.

In this invention, first, 1 to 20% by weight of an unsaturated monomer having an acidic group is added in the absence of a solvent or in the presence of a small amount of a solvent.
and 99 to 80% by weight of other unsaturated monomers copolymerizable with this, and a weight average molecular weight M104 to M106 copolymer is synthesized.

A solvent is used in the case of a monomer composition that is difficult to undergo bulk polymerization or for the purpose of facilitating viscosity control, but the amount used is usually 20% by weight or less. As the solvent used here, various general organic solvents can be used, but preferably alcoholic hydrophilic solvents such as methanol, ethanol, n-phthanol, n-propanol, isopropyl alcohol, and 5eC-phthanol, or hydroxyl group, carboxyl group,
It is desirable to use an oligomer or prepolymer having a hydrophilic group such as amide 7 group.

Examples of unsaturated monomers having particularly important acidic groups in the monomer components include unsaturated carboxylic acid having a carboxyl group as an acidic group, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid. acid, styrene sulfonic acid, allyl sulfonic acid, sulfopropyl acrylate, 2-acryloyloxynaphthalene-2-
Sulfonic acid, 2-methacryloyloxynaphthalene-2
Examples of acidic groups include unsaturated sulfonic acids having a sulfonic group, such as -sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and 2-acryloyloxybenzenesulfonic acid, and other acids having an acidic group. One or more of these may be used.

The amount of unsaturated monomers to be used should be 1 to 20 tonne % based on the total monomers, for example, in the case of unsaturated carboxylic acids, it is particularly preferable to use 5 to 15 wt. Especially in the case of unsaturated sulfonic acids, it is preferably from 3 to 10% by weight.

This usage amount is less than 1% by weight or 20% by weight
If it exceeds 7, good results are obtained for hydrosylation.
4+ 'I can't do it.

Other copolymerizable unsaturated monomers used in combination with such unsaturated monomers can be arbitrarily selected from various ethylenically unsaturated monomers. For example, an alkyl group having 1 to 15 carbon atoms, preferably 3 to 10 carbon atoms, acrylic esters and methacrylic esters, other vinyl ethers, vinyl esterophores, acrylonitrile, acrylamide, hydroxyalkyl acrylates, styrene, vinyl chloride, ethylene, intramolecular Examples include ethylenically unsaturated monomers having a functional group such as an amine group, and one or two of them are selected and used depending on the purpose of use.

Synthesis of a copolymer using a small amount of solvent is carried out by a conventionally known method. Each of the monomers described in 1. is charged into a reactor, the atmosphere is replaced with nitrogen, and organic peroxides, azo compounds, etc. The polymerization may be carried out by heating using an appropriate polymerization initiator and, if necessary, a polymerization regulator such as mercaptan. At this time, if desired, additives such as tackifiers, softeners, movable agents, fillers, and pigments may be added in advance to the reactor. These additives can also be added each time the copolymer is synthesized.

It is necessary that the weight average molecular weight of the copolymer synthesized by the above method is set within the range of 104 to 106. The reason for this is as follows: if it is less than 104, the physical properties, such as cohesive force and physical strength, will be poor when made into a coating or other molded product, and if it exceeds 106, it will have a high viscosity. This is because it interferes with this alkali treatment and tends to generate hydrosil.

In the present invention, an alkali or aqueous alkali solution is then added to the copolymer having the molecular weight as described above and which may contain a small amount of the solvent to neutralize the copolymer while stirring. The treatment temperature at this time is kept at a constant temperature depending on the type and properties of the copolymer, but it is generally 40-95°C.
It is. Alkali or aqueous alkaline solutions used for neutralization include ammonia, aqueous ammonia, caustic sorter,
Examples include aqueous solutions of caustic alkalis such as caustic potash, and they may be used in an amount of about 1150 to 2 equivalents relative to acidic groups such as carboxyl groups and sulfone groups in the copolymer.

After this neutralization treatment, if you continue stirring to mix well and then gradually add water, a so-called phase inversion phenomenon will occur for a certain period of time, and water will form a continuous layer and copolymerize in this layer. An 0/W type dispersion in which the combined particles are dispersed is produced. After this dispersion is stopped, a necessary amount of water is gradually cooled to adjust the viscosity and solid content concentration of the dispersion. The viscosity is generally 30 to 1,000 poise at 25°C, and the solids concentration is usually 10 to 60% by market weight.

The dispersion thus obtained is a hydrosil in which the average particle diameter of the copolymer as the dispersed particles is 0.01 to 0.1 μm, and the copolymer particles are uniformly and stably dispersed in water. It exhibits the above-mentioned excellent performance when it is cast alone or with the addition of a crosslinking agent etc. onto a carrier and dried to form a coating film, or when it is cured and molded into other molded products.

Examples of this invention will be described below.

Example 1 n-butyl methacrylate 60g ethyl acrylate 60Q methacrylic acid
15g azobisvaleric acid 015g lauryl mercaptan 0.075g 15& of the above compositions were charged into a fourth flask (No. 11), and the flask was purged with nitrogen for 40 minutes without stirring. The remaining amount was added dropwise from the dropping funnel and the mixture was reacted at 83°C for 4 hours to synthesize a copolymer with a weight average molecular weight of 8 x 105 (according to GPC).

Next, 1/1 to the carboxyl group of this copolymer
86 by adding 6 equivalents of caustic soda aqueous solution (20% by weight)
The mixture was neutralized at a temperature of .degree. C., and 250 parts of water was gradually added dropwise to 100 parts of the copolymer for about 2 hours while stirring.

When 150 parts of water was added dropwise, a phase inversion phenomenon occurred in which the continuous layer became water.

The hydrosil thus obtained has a viscosity (25
"C) had a solid content of 175 poise, a solid content concentration of 26.5% by weight, and an average particle diameter of 0.08 μm (heat drying with a nanosizer was performed to form a film with a thickness of 50 μm.

The results of examining the water resistance and other properties of this film are shown in Table 1 below.

(Note) 1) Weight average molecular weight 2 obtained by emulsion polymerization of a monomer mixture having the same composition as in Example 1 using thioglycolic acid as a chain transfer agent and potassium persulfate as a polymerization initiator.
This is a test result of a film made from a polymer emulsion of x104.

2) Measured values at a tensile speed of 5 Q mm and 7 minutes.

Example 2 n-octyl acrylate 651i' methyl methacrylate 35g acrylic acid
10g azobisisobutyronitrile 0.
1 g 5 ec-butanol 5 g Of the above composition, 10 Da of the monomer mixture and 5 g of 5 ec-7' tanol were charged into a fourth flask (No. 11), and the flask was purged with nitrogen at 40° C. for 40 minutes without stirring. Then, 0.1 g of azobisisobutyronitrile was added, and after completely dissolving, the temperature was raised to 80°C. The remaining monomer mixture is then added to the dropping roller from 1 to 2 at a rate of about 0.871 i'/min.
85 parts were added dropwise to the hair for 4 hours and reacted at 5°C for 4 hours to obtain a weight average molecular weight of 6.5 x 105 (according to GI'C).
A copolymer was synthesized.

At the same time, 1/8 of the carboxyl group of this copolymer
Add an equivalent amount of ammonia aqueous solution (25% by weight) to neutralize 80 parts at a temperature of 3°C, and then, without further stirring, add about 200 parts of water to 100 parts of the copolymer. I applied it to my hair for an hour and then gradually dripped it. When 120 parts of water was added dropwise, a phase inversion phenomenon occurred in which the continuous layer became water.

The hydrosil thus obtained has a viscosity (25
"C) had 270 voices, a solid content concentration of 34.9% by weight, and an average particle size of 0.06 μn). Using this hydrosil, a film was prepared as shown in Example 1 below,
The characteristics were evaluated in the same manner as in Example 1, and the results were as shown in Table 2 below.

Example 3 n-octyl acrylate 65g methyl methacrylate 35g acrylic acid
2g azobisisobutyronitrile 0.1if
sec-butanol 5g With the above raw material composition, a copolymerization reaction was carried out in the same manner as in Example 2,
A copolymer with a weight average molecular weight of 6 x 105 (according to GPC) was synthesized.

This copolymer was neutralized in the same manner as in Example 2 using an ammonia aqueous solution (25% by weight) of 1 equivalent to the carboxyl group contained therein, and then, while stirring, the copolymer was 300 parts of water was gradually added dropwise to 100 parts. When 180 parts of water was added dropwise, a phase inversion phenomenon occurred in which the continuous phase became water.

The hydrosil thus obtained has a viscosity (25
``C) has 55 voids, solid content concentration is 25.1% by weight,
The average particle diameter was 0.09 μm. Using this hydrosil, a film was formed according to Example 1, and the characteristics were evaluated in the same manner as in Example 1. The results were as shown in Table 2 below.

Example 4 n-octyl acrylate 65g methyl methacrylate 35g acrylic acid
20g Azobisisobutyronitrile 0.19
sec-butanol 5g With the above raw material composition, a copolymerization reaction was carried out in the same manner as in Example 2,
Weight average molecular weight 6.8X105 (according to G l' C)
A copolymer was synthesized.

This copolymer was neutralized in the same manner as in Example 2 using an ammonia aqueous solution (25% by weight) in an amount of 1/20 equivalent to the carboxyl groups contained in the copolymer. 150 parts of water was gradually added dropwise to 100 parts of the polymer. When 80 parts of water was added dropwise, a phase inversion phenomenon occurred in which the continuous phase changed to water.

The hydrosil thus obtained has a viscosity (25
"C) had 370 voids, a solid content concentration of 43.6% by weight, and an average particle diameter of 0.03 μm. Using this hydrosil, a film was formed according to Example 1, and The results of the characteristic evaluation conducted in the same manner [6] were as shown in Table 2.

As is clear from the test results in Table 2 and above, the hydrosil obtained by the method of this invention can form a film with excellent water resistance, and the mechanical properties of the support rod are also fully satisfactory. I understand.

Patent applicant: Nitto Electric Industry Co., Ltd.

Claims (1)

[Claims] (1) In the presence of no solvent or a small amount of solvent, from 1 to 20% by weight of an unsaturated monomer having an acidic group and 99 to 80% by weight of another unsaturated monomer that can copolymerize with dirt. Synthesize a copolymer having a weight average molecular weight of 104 to 106, add an alkali or aqueous alkali solution to neutralize part or all of the acidic groups in the copolymer molecule, and further add water. By phase inversion, the above copolymer has an average particle size of 0.01 to 0.
．． A method for producing hydrosil, characterized by obtaining hydrosil stably dispersed in water in a range of 1 μm.