JPS587656B2 - How to use this service - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing expandable thermoplastic polymer particles, and more specifically, the thermoplastic polymer particles are dispersed in water, and the particles are dispersed in water in the presence of a suspension stabilizer. In a method for producing expandable thermoplastic polymer particles by adding a readily volatile organic liquid blowing agent having a boiling point lower than the softening point of
By using calcium carbonate surface-treated with an organic substance as a suspension stabilizer, a production method with extremely excellent suspension stability is provided.

A readily volatile organic liquid blowing agent having a boiling point lower than the softening point of the particles is added to a suspension in which thermoplastic polymer particles are dispersed, and the blowing agent is impregnated into the particles to generate foaming heat. When producing plastic polymer particles, the surface of the polymer particles is softened by the blowing agent during the impregnation, and the particles are bonded together.

Suspension stabilizers are generally used to prevent binding of the polymer particles during this blowing agent impregnation.

Such suspension stabilizers include fine powders that are poorly soluble in water, such as tricalcium phosphate, magnesium pyrophosphate,
It is known that inorganic substances such as calcium carbonate, calcium silicate, bentonite, metal salts of fatty acids such as calcium stearate and zinc stearate, and organic fine powders such as fatty acid bisamides such as ethylenepis stearamide can be used. However, these fine powders must be used alone as suspension stabilizers, and in order to prevent the polymer particles from being bonded together by blowing agents and softeners, they must be used in large quantities, making them industrially less advantageous. Not in a good way.

Therefore, when using these poorly water-soluble fine powders, a method is generally adopted in which they are used in combination with a surfactant to improve suspension stability.

For example, for inorganic fine powders, an anionic surfactant is used to enhance the suspension ability by helping the fine powders to diffuse in water and preventing them from agglomerating.

Among these, a method using a combination of tribasic calcium phosphate and sodium dodecylbenzenesulfonate is well known.

The present inventors also investigated various inorganic fine powders and anionic surfactants, but the inorganic substances include phosphates such as dibasic and tribasic calcium phosphate, tribasic magnesium phosphate, and magnesium pyrophosphate, and birophosphate. It has been confirmed that the salt has the best suspension stability.

In addition, not only anionic surfactants but also nonionic and amphoteric surfactants can be used for organic fine powders such as calcium stearate and ethylene bisstearamide, but they are said to be less effective than anionic surfactants for inorganic fine powders. This is the general view.

In contrast to these methods, which use fine powders that are poorly soluble in water as dispersants,
Water-soluble organic substances having protective colloidal properties such as partially saponified polyvinyl alcohol, polyacrylates, polymethacrylates, polyvinylpyrrolitone, carboxymethylcellulose, ethylcellulose, methylcellulose, and sodium alginate are also often used as suspension stabilizers. Are known.

Moreover, these are usually used in combination with a surfactant or something like sodium pyrophosphate, rather than being used alone.

However, when these water-soluble organic substances are used as suspension stabilizers, the temperature at which the polymer particles are stably impregnated with the blowing agent without bonding and can be scaled is at most 9.
Impregnation is difficult at higher temperatures than 0°C.

In addition, when these water-soluble organic substances are used, it is extremely difficult to remove them through wastewater treatment, and from an environmental conservation perspective,
Not desirable.

In addition, according to Japanese Patent Publication No. 47-25147, as a method of preventing the bonding of polymer particles during impregnation with a blowing agent, an oil agent such as mineral oil, polyethylene glycol, dibutyl phthalate, etc. is applied to the surface of polystyrene particles in advance, and then carbonic acid A method has been shown in which polystyrene particles are suspended in water to which fine powders such as calcium, calcium silicate, Merck, etc., which cannot be dissolved by water and a blowing agent, are attached. The disadvantages are that it is necessary to subject the combined particles to a two-step surface treatment, and that a small amount of a water-soluble organic substance such as polyvinyl alcohol must be used in combination.

As a result of intensive research in view of the above points, the present inventors have found that by using fine surface-treated calcium carbonate, it is possible to eliminate the need to use a surfactant or a water-soluble organic substance with protective colloidal properties. It was discovered that excellent suspension stability can be achieved with a small amount of use.

That is, the present invention provides a manufacturing method in which thermoplastic polymer particles are dispersed in water to obtain expandable thermoplastic polymer particles in the presence of a blowing agent, in which calcium carbonate surface-treated with an organic substance is made to exist in water. The gist of the present invention is a method for producing expandable thermoplastic polymer particles characterized by the following.

According to the method of the present invention, calcium carbonate whose surface has been treated with an organic substance is sufficient as the suspension stabilizer. The presence of antifoaming agents and water-soluble organic substances caused intense foaming, and it was considered essential to use antifoaming agents, but this kind of foaming was not observed in the method of the present invention, which shows that it is very superior. .

Furthermore, from the perspective of wastewater treatment, it can be easily removed by coagulation-sedimentation method or flotation separation method, so suspension stabilizers using a combination of phosphates or pyrophosphates and anionic surfactants, or protective colloids can be used. This provides an industrially more advantageous method than using strong organic substances as suspension stabilizers.

Calcium carbonate surface-treated with an organic substance used in the method of the present invention is one surface-treated with stearic acid, fatty acid or fatty acid salt such as fatty acid calcium, resin acid whose main components are diterpenic acid and abietic acid, lignin, etc. Can be mentioned.

As for the particle size, extremely fine particles with an average particle size in the range of 0.03 μm to 0.15 μm are preferable.

Furthermore, the method of the present invention includes composites of calcium carbonate and other substances, such as composites of calcium carbonate and magnesium carbonate surface-treated with resin acids.

The calcium carbonate surface-treated with the organic substance is usually o.o. relative to the thermoplastic polymer particles used. i~1% by weight
used.

If it is less than 0.1% by weight, bonded particles tend to occur, which is not preferable.

On the other hand, if the amount is more than 1% by weight, the suspension stabilizing effect will not change and it will only become uneconomical.

In addition, when unsurface-treated calcium carbonate is used alone, even if it is used in an amount as high as 2% based on the polymer particles, a large number of bonded particles are still generated. Find out whether fine powder is effective in preventing bonding.

In addition, when surface-treated calcium carbonate is used as a suspension stabilizer, it has excellent properties without forming bonded particles even in the presence of a blowing agent under a wide range of suspension system temperatures from room temperature to 125°C. It can be said that it has good suspension stability.

When using these surface-treated calcium carbonates as a suspending agent, it is most desirable to use them alone, but they may also be used in combination with other inorganic fine powders.

However, the combined use of surfactants and organic substances having protective colloidal properties generally does not tend to give good results.

However, it can also be used under limited conditions.

As mentioned above, when surface-treated calcium carbonate is used as a suspension stabilizer, it can be used in a small amount and stably as a foaming agent without using surfactants or organic substances with protective colloid properties as dispersion aids. The economic effect cannot be overlooked as it can be impregnated with water.

The thermoplastic polymer particles used in the method of the present invention include polystyrene, copolymer particles containing styrene as a main component, such as styrene-acrylic acid ester copolymer particles, and styrene-methacrylic acid ester copolymer particles. particle,
Examples include styrene-butadiene copolymer particles.

In addition, methyl methacrylate polymer particles, copolymer particles with methacrylic acid ester containing methacrylic acid ester as a main component, such as methyl methacrylate-styrene copolymer particles, ethyl methacrylate-styrene copolymer particles, methacrylic acid Examples include methyl-α-methylstyrene-butyl acrylate copolymer particles.

Other crosslinked polyethylene polymer particles are also included.

Further, the blowing agent used in the method of the present invention is an organic compound that is liquid or gaseous at room temperature, has a boiling point of 100°C or less, and does not dissolve or swell the polymer particles;
Particular preference is given to hydrocarbons or halogenated hydrocarbons, such as propane, butane, pentane, hexane, cyclohexane, heptane, dichlorodifluoromethane and the like.

These blowing agents are contained in the polymer particles in an amount of 3 to 15% by weight.

Additionally, flame retardant expandable polymer particles can be made using known flame retardants such as tris(2.3 diglomoprobil) phosphate, hexabromocyclododecane, and flame retardant aids such as organic peroxides. You can also do that.

In addition, dyes, antistatic agents, etc. may also be present.

The present invention will be specifically explained below using Examples.

Example 1 Calcium carbonate whose surface was treated with 2200 g of water and a resin acid whose main component is abietic acid as a suspension stabilizer (manufactured by Shiraishi T-gyo ■, trade name: Hakuenka TDD')6.
Next, 2200 g of polystyrene particles having a particle size of 16 to 24 mesh were dispersed in the flask, and the flask was sealed and 220 g of pentane was press-injected as a blowing agent at a temperature of 90°C.

Next, the temperature was raised to 120℃ over 40 minutes, and then the temperature was raised to 120℃ for 1 hour.
After keeping it for a long time to allow sufficient impregnation, it was cooled to 30°C and taken out.

As a result, no bonded particles were observed, and good expandable polystyrene particles were obtained.

Example 2 A composite of calcium carbonate and magnesium carbonate (manufactured by Shiraishi Kogyo Co., Ltd., product name: Hakuenka AA) 6 which was surface-treated with 22001 water and a resin acid containing abietic acid as the main component as a suspension stabilizer in a 5.6 liter reactor. Add 1 .6r, then 16-24
2200r of polystyrene particles having a particle size of Menosh were dispersed and sealed, and at a temperature of 100°C without stirring,
220 g of pentane was injected as a blowing agent over 3 minutes.

Next, the temperature was raised to 115°C over 15 minutes, and the temperature was increased to 115°C for 2 hours.
After holding for a while, it was cooled to 30°C and taken out.

As a result, expandable polymethylene particles without bonded particles were obtained.

Example 3 2200 ml of water was added to a 5.61 ml reactor. Calcium carbonate (Shiraishi T) surface treated with stearic acid and suspension stabilizer.
11.0 g of styrene-butyl acrylate copolymer particles (product name: Hakuenka CCR, manufactured by W) were added, and then 2200 g of styrene-butyl acrylate copolymer particles consisting of 2 parts of butyl acrylate and 98 parts of styrene were dispersed and sealed, and then a blowing agent was added while stirring. Then, 220 g of butane was injected under pressure and the temperature was raised to 90°C.

After being impregnated at a temperature of 90°C for 3 hours, it was cooled to 30°C and taken out.

As a result, expandable styrene-butyl acrylate copolymer particles without bonded particles were obtained.

Example 4 11.0 g of calcium carbonate surface-treated with lignin (trade name: Calmos, manufactured by Shiraishi Kogyo ■) as a suspension stabilizer in 2200 r of water was added to a 5.6 liter reactor, and then 90 parts of methyl methacrylate, Methyl methacrylate-butyl acrylate-α-methylstyrene copolymer particles 220M consisting of 5 parts of butyl acrylate and 5 parts of α-methylstyrene
220 ft of pentane was press-injected as a foaming agent while the container was sealed and stirred.

Next, the temperature was raised to 100°C over 1 hour, and after being impregnated for 10 hours, it was cooled to 30°C and taken out.

As a result, good expandable copolymer particles without bound particles were obtained.

Comparative Example 1 In a 5.6 J reactor, 2200 r of water and calcium carbonate without surface treatment (manufactured by Shiraishi Kogyo ■) were used as a suspension stabilizer.
442 (product name: Akadama) was added, then polystyrene particles 2200r having a particle size of 16-24 mesh were dispersed, sealed, and pentane 22 was added as a blowing agent at a temperature of 90°C.
0g was press-fitted.

Next, the temperature was raised to 120°C over 40 minutes and maintained for 1 hour, and then cooled to 30°C and taken out.

As a result, a large number of bonded particles were generated.

This comparative example was carried out to compare with Example 1, and in Example 1, no bound particles were observed when the calcium carbonate surface-treated with resin acid was used in an amount of 0.3% based on the polystyrene particles. On the other hand, in Comparative Example 1, a large number of bonded particles were still formed even when 2% calcium carbonate was used, which shows how excellent the suspension stability of surface-treated calcium carbonate is.

Claims (1)

[Claims] 1. A manufacturing method in which thermoplastic polymer particles are dispersed in water to obtain foamable thermoplastic polymer particles in the presence of a blowing agent, in which fatty acids or fatty acid salts such as stearic acid, fatty acid calcium, diterpenic acid, and abietic acid are mainly used. A method for producing expandable thermoplastic polymer particles, which comprises allowing calcium carbonate surface-treated with an organic substance selected from resin acids and lignin to exist in water.