JPS6031329B2 - Hydrosol production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is a hydrosol, that is, a particle size of 0.01 to 0.1r.
A new method for producing a dispersion in which polymer particles of m are stably dispersed in water, and is characterized by hydrosolizing 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, as a method for producing a hydrosol, as shown in Japanese Patent Publication No. 46-22343 and Japanese Patent Application Laid-Open No. 50-19842, polymer particles having carboxyl groups (with a particle size of about 0 .3~0
．． The so-called stripper full method involves scraping off the surface of high-speed Takaazusa particles of 7rm) using an alkali such as caustic potash, caustic soda, or ammonium hydroxide to make fine particles with a particle size of about 0.01 to 0.1 French m. However, according to the above-mentioned conventional method, which has been generally adopted, the emulsifier is mixed into the hydrosol, resulting in poor water resistance of coating films and other molded products obtained therefrom.

Furthermore, there is a limit to the molecular weight of a polymer that can be converted into a hydrosol, and generally, when the weight average molecular weight is 1 pi (10,000) or more, it becomes difficult to form a hydrosol. 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- A copolymer with a weight average molecular weight of 1 to 1 is synthesized, consisting of 2% by weight of 2% by weight and 99% to 8% by weight of other unsaturated monomers that can be copolymerized with this copolymer, and an alkali or aqueous alkali solution is added to this copolymer. In addition, neutralizing part or all of the acidic groups in the copolymer molecules,
Production of a hydrosol characterized by adding water to the mixture and inverting the phase to obtain a hydrosol in which the above-mentioned copolymer is stably dispersed in water with an average particle size in the range of 0.01 to 0.1 mm. It's in the method.

That is, the inventors did not use a polymer emulsion as in the past, but compared the molecular weight of a specific copolymer with acidic groups obtained by bulk polymerization or solution polymerization using a small amount of solvent. After neutralizing the copolymer with an alkali or an aqueous alkali solution, the copolymer has an average particle size of 0.01 to 0.1 mm by adding water and inverting the phase. We succeeded in obtaining a hydrosol that was stably dispersed in water within this range.

The hydrosol according to the present invention obtained in this way is
When made into coatings or other molded products, it exhibits much improved water resistance compared to conventional hydrosols, and because the molecular weight of the polymer is relatively high, various physical properties are also good. , it exhibits excellent performance comparable to coatings formed from general organic solvent solutions.

For this reason, it has a wider range of applications than conventional hydrosols, including paints, paper sizing agents, adhesives, adhesives, etc.
It can be extremely advantageously applied to various fields such as overcoating agents, exterior materials, interior materials, and films. In this invention, first, in the absence of a solvent or in the presence of a small amount of solvent, 1 to 2% by weight of an unsaturated monomer having an acidic group and 99 to 80% by weight of an unsaturated monomer copolymerizable therewith are added. A copolymer having a weight average molecular weight of 1 to 1 is synthesized by weight%.
A solvent is used in the case of a bulk polymerized thick monomer composition or for the purpose of facilitating viscosity control, but the amount used is usually 2% by weight or less.

Further, as the solvent used here, various general organic solvents can be used, but methanol, ethanol, n-4 butanol, and n-f are preferred. Alcohol-based hydrophilic solvents such as lo/f alcohol, inpropyl alcohol, sec-butanol, or hydroxyl groups, carboxyl groups,
It is desirable to use prepolymers without oligomers having hydrophilic stems such as amino groups. Examples of unsaturated monomers having particularly important acidic groups in the monomer components include unsaturated monomers having carboxyl groups as acidic groups, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid. Metariki rubonic acid, styrene sulfonic acid, allyl sulfonic acid, sulfopropyl acrylate, 2-acryloyloxynaphthalene-2-sulfonic acid, 2-methacryloxynaphthalene-02-sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2 - Examples of acidic groups such as acryloyloxybenzenesulfonic acid include unsaturated sulfonic acids having a sulfonic group, and may also have other acidic groups, one or more of these. use.

The amount of the unsaturated monomer used must be 1 to 2% by weight based on the total monomers, for example, in the case of unsaturated carboxylic acid, it is particularly preferably 5 to 15% by weight, and unsaturated sulfone Particularly preferred in the case of acids is 3 to 1% by weight.

This usage amount is less than 1% by weight or 2% by weight
If it exceeds 100%, no good results will be obtained in hydrosolization. Other copolymerizable unsaturated monomers used in combination with such unsaturated monomers can be arbitrarily selected from various ethylenically unsaturated monomers.

For example, the alkyl group has 1 to 15 carbon atoms, particularly preferably 3 carbon atoms.
~10 acrylic acid esters and methacrylic acid esters,
Other examples include vinyl ether, vinyl ester, acrylonitrile, acrylamide, hydroxyalkyl acrylate, styrene, vinyl chloride, ethylene, and ethylenically unsaturated monomers having functional groups such as amino groups in the molecule, depending on the intended use. Type 1 or 2
Select and use more than one species. Synthesis of a copolymer without a solvent or using a small amount of solvent is carried out by a conventionally known method, in which each of the above monomers is charged into a reactor, the atmosphere is replaced with nitrogen, and an appropriate polymerization process such as an organic peroxide or an azo compound is carried out. The polymerization may be carried out by heating using an initiator and, if necessary, a polymerization regulator such as a mercaptan.

At this time, if desired, tackifiers, softeners, plasticizers, fillers, pigments, etc. may be added in advance to the reactor. These additives can also be added each time the copolymer is synthesized. The copolymer synthesized by the above method must have a weight average molecular weight in the range of 1 to 1.

The reason for this is as follows: if it is less than 1 pi, the physical properties such as cohesive force and physical strength will be poor when used as a coating or other molded product, and if it exceeds 1 pi, the viscosity will be high. This may interfere with the alkaline treatment,
This is because it becomes difficult to generate hydrosol. In this invention, next, an alkali or an aqueous alkali solution is added to the polymer having the above-mentioned molecular weight and which may contain a small amount of the solvent for neutralization.

The treatment temperature at this time is kept at a constant temperature depending on the type and properties of the copolymer, but is generally from 40 to 9,500 ℃. Examples of the alkali or alkaline aqueous solution used for neutralization include ammonia, aqueous ammonia, caustic soda, and aqueous solutions of caustic soda such as caustic potash. It may be used at a ratio of 1/50 to 2 equivalents. After this neutralization treatment, if water is gradually added while continuing to mix thoroughly, a so-called phase inversion phenomenon will occur at regular intervals, and the water will form a continuous layer and co-polymerize in this layer. A 0/W type dispersion in which the combined particles are dispersed is produced.

After forming this dispersion, gradually add the required amount of water,
Adjust the viscosity and solids concentration of the dispersion. The viscosity is generally 30 to 1,000 poise at 2500, and the solid content concentration is usually 10 to 60% by weight. The dispersion thus obtained is a hydrosol in which the copolymer particles as dispersed particles have an average particle size of 0.01 to 0.1 mmnl, and the copolymer particles are uniformly and stably dispersed in water. When this is cast alone or with a crosslinking agent added onto a carrier and dried to form a coating, or when cured and molded into other molded products, it exhibits the excellent performance described above. .

Examples of this invention will be described below.

In addition, in the following, parts mean parts by weight. Example 1 n-butyl methacrylate 60 ethyl methacrylate 60 methacrylic acid 15 azobis glutinous acid
0.15 Tarawalylmerkabutane
0.075 ta 15 of the above compositions
Pour the liquid into the four-necked flask and drink it for 40 minutes while praying.
The atmosphere was replaced with nitrogen for a minute.

While dropping the remaining amount from the dropping funnel, the reaction was carried out at 83°C for 4 hours, and the weight average molecular weight was 8 x 1 pi (by GPC).
A copolymer was synthesized. Next, a caustic soda aqueous solution (2
% by weight) at a temperature of 86°C, and then, while further concentrating, 25 parts of water per 10 parts of the copolymer was gradually added over a period of about 2 hours. dripped.

When 15 eaves of water was dropped, a phase inversion phenomenon occurred in which the continuous layer became water.

Hido obtained in this way.

The sol has a viscosity (2500) of 175 poise, a solid content concentration of 26.5% by weight, and an average particle diameter of 0.08 French m (
(by Nanosizer). This hydrosol, 7
Cast on a 5Am thick polyester film and heated at 110o
The film was dried by heating for 1 minute at 50°C to form a film with a thickness of 50 cm. The results of examining the water resistance and other properties of this film are shown in Table 1 below. 1st
Table (Note) 1 Weight average molecular weight 2 obtained by emulsion polymerization of a monomer mixture with 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 1× polymer emulsion.

2 This is a measured value divided into tensile speeds of 50 legs/min.

Reference Example 10 parts of the copolymer synthesized in Example 1 were placed in a flask, and 1/1 part of the copolymer was added to the carboxyl group of the copolymer.
16 equivalents of caustic soda aqueous solution (2% by weight) was brought into contact with 10 parts of the copolymer, and 25 parts of water was added at the same time to give 90q0
The field was heated and flooded for one hour at a temperature of .

Although the copolymer absorbed water and swelled slightly, there was no phase inversion, and the water and copolymer remained separated into two phases. In addition, when the above-mentioned digestion was carried out by dropping flies, the copolymer was fragmented by the shearing force of the flies, producing grain-sized particles of rice, and these particles became a turbid liquid suspended in water.

However, when the feeding was stopped, the particles immediately precipitated and separated into two phases, a copolymer precipitate and a transparent aqueous phase, and the separated copolymer particles immediately self-agglomerated. Further, even when the salt immersion temperature was 100 qo, the above binding results were obtained.
As described above, by the so-called digestion method in which a copolymer and an alkaline aqueous solution are heated and mixed at once, it has not been possible to obtain an aqueous dispersion in which the copolymer is stably dispersed in water as colloidal particles.

Example 2 n-octyl acrylate 65 methyl methacrylate 35 acrylic acid
10 seconds Azobisisobutyronitrile 0.1 seconds Butanol
Five days later, of the above composition, 10 times the monomer mixture and 5 times sec-butanol were charged into a four-necked flask, and the flask was purged with nitrogen at 40°C for 40 minutes while shaking.

Then, 0.1 tsp of azobisisobutyronitrile was added, and after completely dissolving, the temperature was raised to 8,000 ℃. Next, the remaining monomer mixture was passed through the dropping funnel at a rate of about 0.87 m/min over a period of 2 hours, and reacted at 85 ± 5°C for 4 hours, resulting in a weight average molecular weight of 6.5 × 1 mm (GPC ) was synthesized. Next, 1/8 equivalent of ammonia aqueous solution (25% by weight) was added to the carboxyl group of this copolymer to neutralize it at a temperature of 80±3°C, and then the copolymer was further copolymerized. 10 polymers versus 2
00 parts of water was gradually added dropwise over a period of about 2 hours.

When 120 parts of water was added dropwise, a phase inversion phenomenon occurred in which the continuous layer became water.

The hydrosol thus obtained has a viscosity (25
℃) is 270 poise, and the solid content concentration is 34. $wt%,
The average particle diameter was 0.06 m.

Using this hydrosol, a film was prepared 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
3 n-octyl acrylate 65 methyl methacrylate 35 methacrylate
2. Azobisisobutyronitrile
0.1 sec-butanol
A copolymerization reaction was carried out using the above raw material composition as in Example 2, and the weight average molecular weight was 6 x 1 (G
A copolymer of (by PC) was synthesized.

1 for the carboxyl group contained in the copolymer.
Neutralization was carried out in the same manner as in Example 2 using an equivalent amount of ammonia aqueous solution (25% by weight), and then 30 parts of water was gradually added dropwise to 100 parts of the copolymer while stirring. did.

When 18 anchors of water were dropped, a phase inversion phenomenon occurred in which the continuous phase became water.

The hydrosol thus obtained has a viscosity (25
q0) is 55 poise, solid content concentration is 25.1% by weight,
The average particle diameter was 0.09 mm.

Using this hydrosol, 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 65 methyl methacrylate 35 methacrylate
20 sec Azobisisobutyronitrile 0.1 sec-Butanol
With the above raw material composition, co-merging was carried out in the same manner as in Example 2, and the weight average molecular weight was 6.8.
A copolymer of x1 and (by GPC) 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 group contained in the copolymer, and then copolymerized while holding a candle. 15 parts of water was gradually added to 100 parts of the mixture.

When 80 parts of water was added dropwise, a phase inversion phenomenon occurred in which the continuous phase became water.

The hydrosol thus obtained has a viscosity (25
oo) Ga is 370 poise, solid content concentration is 43.6% by weight
The average particle diameter was 0.03 mm.

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

Claims (1)

[Claims] 1 A weight average consisting of 1 to 20% by weight of an unsaturated monomer having an acidic group and 99 to 80% by weight of another unsaturated monomer copolymerizable with it in the absence of a solvent or in the presence of a small amount of solvent. Synthesize a copolymer with a molecular weight of 10^4 to 10^6, add an alkali or alkaline aqueous solution to neutralize part or all of the acidic groups in the copolymer molecule, and then add water. The above copolymer is phase-inverted to obtain an average particle size of 0.01~
A method for producing a hydrosol, characterized by obtaining a hydrosol stabilized in water in the range of 0.1 μm.