JPS5924709A - Production of thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain the titled resin excellent in blendability and free from a need of washing operation, by coagulating an MBS resin latex at a temperature in a specified range to form a coagulated slurry, and adding thereto an alkaline substance at a temperature in a specified range to adjust its pH to a specified value. CONSTITUTION:A latex of a thermoplastic resin is formed which contains a monomer component at least 90wt% of which consisting of butadiene, methyl methacrylate, and styrene. Then, this latex is brought into contact with a coagulating solution (an example of a coagulant being sulfuric acid) at a temperature in the range of 0-80 deg.C to form a coagulated slurry and then an alkaline substance (e.g., sodium hydroxide) is added to the obtained slurry so that the pH of the slurry is higher by at least 0.1 than the initial pH, and that the pH of the entire mixture is adjusted to 7.0 or below. Then, the desired thermoplastic resin is obtained by solidifying the coagulated particles of the coagulated slurry by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a thermoplastic resin in which the total amount of butadiene, methyl methacrylate and styrene as monomer components is 90% by weight or more.

Butagen is similar to MBS Kizuki.

Thermoplastic resins containing methyl methacrylate and styrene in a total amount of 90% by weight or more are usually produced by emulsion polymerization. Such thermoplastic resins are usually manufactured as dry powder through a series of manufacturing steps including polymerization, coagulation, washing, dehydration, and drying.
It is used in combination with π-vinyl resin or other thermoplastic resins. Such MIIS resins are used as modifiers to significantly improve the impact resistance of substrate 117j resins.

In particular, it is widely used as an important modifier for polyvinyl chloride resins.

Among the above MBS resin manufacturing processes, the two-phase coagulation and washing steps are usually operated continuously.

The coagulation step is a step in which the polymer latex is first brought into contact with a coagulating liquid to form a coagulated slurry, and then heated and heated in 1 to 3 steps to solidify the polymer.

On the other hand, the washing step is a step in which the solidified polymer slurry is washed with water continuously or batchwise while separating solid and liquid. These coagulation steps and washing steps are important steps that affect the physical properties of the obtained polymer. % vc The coagulation process is a process that primarily determines the powder properties of the resin powder produced, and studies have been conducted to improve powder properties such as bulk specific gravity, dehydration properties, and fluidity index. These studies are aimed at reducing fine powder, which is the main cause of problems in handling, transportability, storage, and drying costs. The main goal was to obtain a powder consisting of hard particles.As a result of these studies, it was possible to improve the powder properties, but since the powder particles became hard, it was relatively difficult to melt and mold the powder. The crosstalk effect caused by the screw extruder or calender device was reduced, and spots and fish eyes were likely to occur on the surface of the molded product, resulting in an unfavorable surface appearance.

Therefore, currently, countermeasures are being taken to reduce the powder properties due to restrictions on resin physical properties, or to strengthen the kneading process at the expense of increased construction and energy costs.

On the other hand, in the cleaning process, it is necessary to wash and remove residual coagulant, residual polymerization aid, residual single F1, etc. This may cause problems in physical properties and operation, such as the tropical color of the resin or smoke emission when melting the resin. In particular, the removal of the residual a% precipitate is the most important operation, and the amount of washing water used is 5 to 30 times that of the normal polymer.However, the use of such a large amount of water is resource-intensive. , it is also unfavorable from an environmental standpoint.

Due to this situation, bulk specific gravity is high (,
The ultimate goal of technological improvement was to produce fine powder-free particles with good dehydration properties and excellent fluidity, and to eliminate the need for such a washing process. As a link to this, in terms of improving powder properties, the janitorial drying method, spray coagulation method, or the present applicant's patent application
3115, which was proposed as a method for producing powder and granules, has been established.Among these technologies, the powder produced by spray drying and spray coagulation is microscopically spherical and Although it has the characteristics of a powder, macroscopically it is a fine powder and requires countermeasures against dust during handling.Also, there are many problems in terms of energy cost, productivity, etc. in manufacturing. The powder and granules according to No. 1 have extremely good powder properties such as bulk specific gravity, dehydration properties, and fluidity, and there is almost no fine powder.However, because the particles become hard, they cannot be mixed with other resins. When used, it is difficult to knead and may cause problems with the surface appearance of the resin in some cases.Therefore, there is a strong need for technological development that overcomes the conflicting powder properties of improving powder properties and improving crosstalk. ing.

In view of the current situation, the present inventors have developed a method with excellent cross-talk characteristics.

Moreover, M, B51il does not require cleaning operations! As a result of intensive research on the method for producing i-fat, we brought MBS resin latex and coagulation liquid into contact at a predetermined temperature range to form a coagulation slurry, and then added an alkaline substance to the coagulation slurry at a predetermined temperature range to determine the pH. The present invention was achieved by discovering that the above object can be achieved by adjusting the value of .

That is, the gist of the present invention is that when producing a thermoplastic resin by coagulating a thermoplastic resin latex in which the total amount of butadiene, methyl methacrylate, and styrene as monomer components is 90% by weight or more, After performing a coagulation operation in the temperature range of ℃ to obtain a coagulated slurry,
Add an alkaline substance to the coagulated slurry in the temperature range of ℃ so that the pI of the coagulated slurry is 0.1 or more higher than the initial pH, and the overall p is 7.0 or less. The method for producing a thermoplastic resin is characterized in that the temperature of the coagulation step 1 is raised after the adjustment to solidify the coagulated particles.

When performing a coagulation operation according to the present invention, coagulants include acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and sulfurous acid; magnesium sulfate, and magnesium chloride.

Polyvalent metal salts such as calcium chloride, aluminum sulfate, aluminum chloride, and potash can be used.

Examples of alkaline substances include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide; alkali metals or alkaline earth metal oxides;
Sodium carbonate, potassium carbonate, zitorium bicarbonate.

Salts of weak acids such as thorium/storium acid and aqueous ammonia;
Examples include water-eleven amines, and the plI of the aqueous solution is 7.
．． Anything that is 0 or more can be used.

In carrying out the present invention, the temperature range during the coagulation operation and the addition of an alkaline substance must be within the range of 0 to 80°C because it is necessary to maintain the polymer particles in the coagulation slurry in a soft agglomerated state.

At a temperature of 0°C, there is a risk of some frozen parts forming, which is not favorable for work. Furthermore, at temperatures exceeding 80°C, the coagulated particles are completely solidified, the micellar particles are fused to each other, and are mechanically and chemically stabilized, so that the effect of the alkali treatment is no longer expressed, thereby achieving the object of the present invention. I can't.

Furthermore, in the present invention, the amount of the alkaline substance added is 0.0.
The pH is within a range such that the pH of the cells and the analytical slurry as a whole after adding the alkaline substance becomes 7.0 or less. This is necessary for effectively reacting the alkaline substance, and is also an essential requirement for maintaining the soft agglomerated state of the emulsified micelles and preventing re-emulsification of the micelle particles. If the amount of alkaline substance added is small enough to not increase the pH difference by 0.1 or more as described above, the above effect will not be sufficiently expressed, which is not preferable.:1'
The pH of the entire slurry after adding the alkaline substance is 7.
Although the above effect can be expected if the added amount exceeds O, there are inconvenient problems such as re-emulsification of micelles in water due to soft agglomerated particles and partial hydrolysis of the polymer, making it impractical for practical industrial use. This is not preferable because it becomes impossible to operate.

In the present invention, the above-mentioned powder or granules are solidified and treated with alkali while retaining their activity without td, and then the coagulated particles are solidified by raising the temperature of the coagulated slurry using a conventional method. For the first time, the solidified material can be subjected to solid-liquid separation using a centrifugal dehydrator or the like.

Butadiene obtained by the method of the invention.

Thermoplastic 4i! composed of methyl methacrylate and styrene! (2) The fat has extremely good crosstalk properties, and the appearance of molded products obtained using it can be improved. Moreover, it does not require a cleaning process during the manufacturing process, and is superior to conventional methods. It has the following characteristics.

Although the rationale for not requiring a washing step in the present invention is still unclear, water-soluble substances 2, such as emulsifiers, which have been rendered insolubilized or poorly soluble by the coagulation operation, are reactivated or solubilized by reaction with alkaline substances. Moreover, since the polymer particles are in a soft agglomerated state before assimilation, the activated water-soluble substance helps improve crosstalk, and also eliminates unnecessary W,
! It is considered that water-soluble substances such as precipitating agents are rendered harmless by reaction with alkaline substances and leak out from the particles into water, making the washing aI operation unavoidably soft.

The present invention will be specifically explained below using Examples.

All numbers in Examples are parts by weight.

Example 1 Butadiene 50? ) [1, 20 parts of methacrylic m-methyl,
Styrene/30 parts, dicumyl peroxide 0.9 parts, octyl mercaptan 066 parts, emulsifier Nonsal TK-
1 (trade name 1 manufactured by Nippon Oil & Fats Co., Ltd.) 1.8 parts, sodium pyrophosphate 0.3 parts.

Ferrous sulfate heptahydrate 0.007 part, glucose 0.4 part.

An emulsion polymer latex obtained by polymerizing 0.15 parts of a crosslinking agent, 0.8 parts of sodium sulfate, 0.03 parts of sodium hydroxide and 180 parts of water in a conventional manner is prepared from 1 part of sulfuric acid and 299 parts of water. A coagulated slurry was obtained. The temperature of the slurry at this time was 50° (II,
pH was 1.3. Next, a 5-ml aqueous solution (23°C) of thorium hydroxide was added to the slurry to adjust pII to 3,
The temperature of the hindlimb slurry, which had been adjusted to 0, was raised to 85°C to solidify the heavy pulp particles. The hindlimb slurry was cooled to 70° C. and dehydrated by centrifugation without washing with water to obtain a wet polymer powder containing 45% water (dry paste).

This wet polymer powder was then thoroughly dried.

Next, 10 parts of the dry polymer was mixed with 90 parts of polyvinyl chloride resin, and this mixture was melt-extruded at 200°C using a molding machine equipped with a T-die at the tip of a screw extruder to a thickness of 0.
．． A 2 mm sheet was prepared.

As a result of examining the fish eyes generated on the obtained sheet, only 11 were observed within an area of 200 mm x 2001 m.

Example 2 Poutadier/40 parts, methyl methacrylate 22 parts, styrene 35 parts, butyl acrylate 3 parts.

Lauroyl peroxide 0.8 parts, lauryl mercaptan 0.3 parts, disproportionated potassium rosinate 2 parts, emulsifier Demol N (trade name, Kao Atlas Co., Ltd. ff) 0.3
parts, potassium hydroxide 0.03 parts.

061 parts of crosslinking agent, 0.6 parts of sodium sulfate and 18 parts of water
An emulsion polymer latex obtained by polymerizing 0 part by a conventional method was brought into contact with a coagulation solution consisting of 3 parts of sulfuric acid and 297 parts of water to obtain a coagulation slurry.

At this time, the temperature of the slurry was 45°C, and the pH was 1.1. Next, a 5 weight polyaqueous solution of potassium hydroxide was added to the slurry to adjust the pH to 3.0, and the temperature of the hindlimb slurry was raised to 83° C. to solidify the polymer particles. Water was added to the hindlimb slurry, cooled to 70°C, and centrifugally dehydrated without washing with water to obtain a wet polymer powder containing 47% water (dry base). This wet polymer powder was then thoroughly dried.

20 parts of the dry polymer were then mixed with 80 parts of polyvinyl chloride resin, and the mixture was fed to a calender and heated at 200°C.
A transparent sheet with a thickness of 0.3 fins was created.

As a result of examining the fish eyes generated on the obtained sheet, 0.2 fish eyes with a diameter of 0.5 tnm or more were observed within a range of 200 mm x 230 mm.

Comparative Example 1 Using the same latex as used in Example 1, a coagulated slurry was obtained in the same manner as in Example 1, and then the temperature of the slurry was immediately raised to 85°C to form coalesced particles. It solidified.

The solidified polymer slurry was washed with water at a magnification of 30 times while being dehydrated, and centrifugally dehydrated to obtain a wet polymer powder containing 46% water (dry base). Thereafter, this wet polymer powder was thoroughly dried, and a sheet having a thickness of 0.2 mm was prepared in the same manner as in Example 1.

As a result of examining the fish eyes generated on the obtained sheet, 32 fish eyes were observed within an area of 200 mm x 200 mm.

Comparative Example 2 Using the same latex as used in Example 1, a coagulated slurry was obtained in the same manner as in Example 1, and the temperature of the slurry was immediately raised to 85°C to form polymer particles'. It solidified.

The solidified polymer slurry is centrifugally dehydrated without washing to remove 4% of the water content.
A wet polymer powder containing 4% (dry paste) was obtained. After sufficiently drying this polymer wet powder, the thickness was reduced to 0 by the same method as in Example 1.
62 sheets were created.

When I investigated the fish eyes that appeared on the obtained sheet, I found 47 fish eyes within a 200 x 200 area.

In addition, the entire sheet turned slightly yellow and a J6 tropical color phenomenon was observed.

Comparative Example 3 Using the same latex as used in Example 2, a coagulated slurry was obtained in the same manner as in Example 2, and the temperature of the coagulated slurry was immediately raised to 85°C to form polymer particles. solidified. The pH of this slurry was 1.0. Next, a 5% by weight aqueous sodium hydroxide solution (25° C.) was added to adjust the pH of the slurry to 3.0, followed by dehydration and drying in the same manner as in Example 2. Next, a seal 1- with a thickness of 0.3 mm was created in the same manner as in Example 2.

When the obtained sheet was examined for fish eyes having a diameter of 0.5 mm or more, 1.3 fish eyes were observed within the range of 200y+++x230cm.

Example 3 20 parts of butadiene, 30 parts of methyl methacrylate, 50 parts of styrene, 1.0 part of lauroyl peroxide, 1.2 parts of octyl mercaptan, 2.0 parts of sodium laurate
part, 0.5 part of emulsifier Demol P (trade name, manufactured by Kao Atlas Co., Ltd.).

An emulsion polymer latex obtained by polymerizing 0.02 parts of sodium hydroxide, 0.2 parts of sodium sulfate, and 160 parts of water by a conventional method is brought into contact with a coagulation solution consisting of 1 part of hydrochloric acid and 299 parts of water to coagulate it. Got slurry. The temperature of the slurry at this time was 40°C, and pl[ was 1.2. Then, a saturated aqueous solution (22° C.) of IJium (bicarbonate) was added to the slurry to adjust the pH to 4.0, and then the temperature of the slurry was raised to 88° C. to solidify the polymer particles. The hindlimb slurry was cooled to 75°C and centrifugally dehydrated (without washing with water) to obtain a wet polymer powder containing 39 g of water (dry base). This wet polymer powder was then thoroughly dried.

Next, 20 parts of the dry polymer were mixed with 80 parts of polyvinyl chloride resin, and the mixture was pressure-fed to a calender and heated to 200°C.
A sheet having a thickness of 0.4 mm was obtained. This sheet is transparent, and when we examined the inside of the sheet using a method that allows light to pass through, we found only 8 fisheyes within the range of 200 x = m-oo-.

Example 4 60 parts of butadiene, 13 parts of methyl methacrylate, 23 parts of styrene, 4 parts of ethyl acrylate.

0.7 part of cumene hydroperoxide, 0.9 part of tertiary dodecyl butane, 1.0 part of disproportionated potassium rosinate, emulsifier Nonsal TK-1 (trade name, manufactured by Bhon Yushi Co., Ltd.) 1. 0 parts, potassium hydroxide 0.02 parts,
Rongalit 0.25 parts.

Ferrous sulfate heptahydrate 0,004 parts, sulfuric acid) IJum 0
．． An emulsion polymer latex obtained by polymerizing 8 parts of sulfuric acid and 155 parts of water in a conventional manner was brought into contact with a coagulating solution consisting of 2 parts of sulfuric acid and 298 parts of water by the method described in Japanese Patent Application No. 73115/1983. Obtain analytical slurry. At this time, the temperature of the slurry was 50' (: l, , pH was 1.2. Then, a 5-weight aqueous solution of thorium hydroxide (21°C) was added to the slurry to adjust the pH of the slurry to 4.0. The temperature of the hindlimb slurry adjusted to 82° C. was increased to solidify the particles.The slurry was then centrifugally dehydrated without washing with water to obtain a wet polymer powder.

The moisture content of this wet powder was 17% (dry base), and after sufficiently drying, the bulk specific gravity was measured and found to be 0.43.

Next, 10 parts of this dry polymer was mixed with 90 parts of polyvinyl chloride resin.
A sheet having a thickness of 0.2 mm was prepared in the same manner as in Example 2.

When the obtained sheet was examined for fish eyes, only 0.2 fish eyes with a diameter of 0.5 mm and 1 mm were observed within an area of 200 mm x 230 mm.

Example 5 Using the same latex as in Example 4, a coagulation slurry was prepared by pouring it into a stirring coagulation solution consisting of 2 parts of sulfuric acid and 298 parts of water. The pH of this slurry was 1.2 and the temperature was 50°C.

Next, a 5% by weight aqueous sodium hydroxide solution (21°C) was added to the slurry to make the slurry (7) pH 4. 'Adjusted to 0. This slurry was centrifugally dehydrated without washing with water heated to 82° C. to obtain a wet polymer powder containing 46φ (dry base) of water. After thoroughly drying this wet powder, the bulk specific gravity of the dry polymer powder was measured and found to be 0.23. In addition, when this polymer was made into a sheet in the same manner as in Example 4 and the physical properties were evaluated, the number of fish eyes with a diameter of 0.5 or more was 0.3.
It was.

Comparative Example 4 Example 4 except that the pH of the slurry was adjusted to 10.0 by adding 5 parts by weight of sodium hydroxide aqueous solution (18°C)
I did the same test. As a result, the moisture content of the dehydrated wet powder was 24% (dry base).

The bulk specific gravity of the dry powder is 0.38, and the diameter inside the sheet is 0.5r.
Fisheye above rar is 200m++'X 2
It was 0.2 pieces per 00 minutes. However, during the dehydration operation, the P cloth frequently became clogged and the P solution also became cloudy, making it impossible to operate on an industrial scale.

Claims (1)

[Claims] When producing a thermoplastic resin by coagulating a thermoplastic resin latex consisting of 90% by weight or more of Petadier/methyl methacrylate and styrene as monomer components, a temperature of 0 to 80 ° C. After performing a coagulation operation in a temperature range of 0 to 80°C to obtain a coagulated slurry, an alkaline substance is added to the coagulated slurry to make the pH of the coagulated slurry 0.1 or more higher than the initial pH. and adjusting the overall pH to 7.0 or less, and then raising the temperature of the coagulated slurry to solidify the coagulated particles.