JPH06157923A - Production of thermoplastic polymer powder - Google Patents

Abstract

PURPOSE:To obtain the subject powder having a high bulk specific gravity by adding a prescribed amount of a polymer, etc., to a coagulated slurry of a specific thermoplastic polymer, pressurizing and compressing the resultant mixture at a temperature within a prescribed range and then disintegrating the pressurized and compressed material. CONSTITUTION:The objective powder is obtained by adding (B) a polymer such as methyl methacrylate and/or an inorganic compound such as talc in an amount of 0.1-10 pts.wt. [based on 100 pts.wt component (A)] to a coagulated slurry of (A) a thermoplastic polymer, having a glass transition temperature T.(A) of the formula {(n) is the number of monomers forming the thermoplastic polymer; W1 to Wn are the weight fraction of respective monomers (i) [(i) is 1 to (n)] in the polymer; Tg1 to Tg2 are the glass transition temperatures ( deg.C) of the polymers composed of the respective monomers} and prepared by carrying out the emulsion polymerization of the monomers (i) such as butadiene or polymer powder obtained by drying the slurry, pressurizing and compressing the component (A) at a temperature within the range expressed by [Tg(A)-30] to [Tg(A)+50] deg.C and then disintegrating the resultant pressurized and compressed material.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a thermoplastic polymer powder having a high bulk specific gravity.

[0002]

2. Description of the Related Art Conventionally, various methods for improving the bulk specific gravity of thermoplastic polymer powder have been studied. For example, in JP-A-55-90520 and JP-A-64-26663, the bulk specific gravity is increased by adding a powder-modifying graft polymer or an inorganic fine powder after solidification of a graft copolymer latex. Ways to improve have been proposed.

[0003]

However, these methods are methods of improving the bulk specific gravity by modifying the surface of the polymer powder to make the packing structure of the particle groups dense. That is, it is difficult to obtain a thermoplastic polymer powder having a sufficiently improved bulk specific gravity because it is not a modification method for increasing the density by reducing voids inside individual particles.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies for the purpose of obtaining a thermoplastic polymer whose bulk specific gravity is improved by reducing voids inside particles, and as a result, a specific polymer and It has been found that a thermoplastic polymer powder having a high bulk specific gravity, in which the inside of particles is compacted, is obtained by compressing and / or crushing a thermoplastic polymer containing an inorganic compound added thereto. Reached

The gist of the present invention is to obtain a coagulation slurry of a thermoplastic polymer (A) having Tg (A) represented by the formula (X), obtained by emulsion polymerization, or a heavy slurry obtained by drying the slurry. The thermoplastic polymer (A) 100 is added to the coalesced powder.
0.1 to 10 parts by weight of the polymer (B) and / or the inorganic compound (C) is added to the parts by weight (Tg (A) -3.
0) to (Tg (A) +50) ° C. The thermoplastic polymer (A) is pressure-compressed in the temperature range shown and then crushed to obtain a thermoplastic polymer powder.

Tg (A) = W ₁ × Tg ₁ + W ₂ × Tg ₂ + ... + W _n × Tg _n- (X) [where n is a unit amount forming the thermoplastic polymer (A)] Is the number of the body, and W ₁ , W ₂ ... W _n are each monomer i (i =
1, 2, represents the polymer (A) weight fraction in _{n), Tg 1, Tg 2} ···, Tg n is the glass transition temperature of the polymer composed of the monomer i (° C. ) Represents. The present invention will be described in more detail below.

Examples of the monomer forming the thermoplastic polymer (A) in the present invention include diene monomers such as butadiene, isopropylene and chloropropylene; alkyl acrylates such as butyl acrylate and octyl acrylate. Monomers; methacrylic acid alkyl ester monomers such as methyl methacrylate and ethyl methacrylate; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; aromatic vinyl monomers such as styrene and α-methylstyrene; Examples thereof include vinyl halide monomers such as vinyl chloride and vinyl bromide; various copolymerizable monomers such as dimethyl siloxane, and two or more of these may be used in combination.

As the thermoplastic polymer (A) in the present invention, a polymer having Tg (A) represented by the formula (X) is used.

When a coagulant is added to the thermoplastic polymer (A) latex, the emulsified state of the latex is destroyed and the emulsified and dispersed polymer particles aggregate to form aggregate particles (hereinafter referred to as coagulated particles). .) Is formed, and the coagulated particles are dispersed in water as a dispersion medium to obtain a slurry. When the polymer (B) and / or the inorganic compound (C) is added to and mixed with this slurry, a mixture in which the polymer (B) and / or the inorganic compound (C) is adsorbed on the surface of coagulated particles is obtained. .

In order to make the coagulated particles in the mixture thus obtained more compact, the slurry usually has a Tg of
(A) The temperature is raised to the above temperature and heat treatment is performed. This treatment is generally called solidification, and the solidification temperature depends on Tg (A), but is usually 60 to 120 ° C. The mixture is recovered as a powder by dehydrating and drying the solidified slurry.

The above process is a case where the polymer (B) and / or the inorganic compound (C) is added to and mixed with the slurry after coagulation. In the present invention, the thermoplastic polymer after solidification and after drying. It is also possible to add and mix with (A). When added after drying, the polymer (B)
And / or the inorganic compound (C) is preferably added in a dry powder state.

The polymer (B) and / or the inorganic compound (C) may be added separately. For example, it can be added at each stage after solidification and drying.

The polymer (B) used in the present invention assists the crushing process by adding it to the thermoplastic polymer (A), and the Tg calculated by the following formula (Y)
It is preferable that (B) is a polymer that is higher than Tg (A) by 50 ° C. or more. Furthermore, Tg (B) is preferably 60 ° C. or higher. Polymer (B) when less than 60 ° C
Are likely to exist in an aggregated state, and the original modifying effect may not be obtained at the time of addition, which is not preferable.

Tg (B) = W ₁ × Tg ₁ + W ₂ × Tg ₂ + ... + W _n × Tg _n- (Y) [where n is a monomer forming the polymer (B)] W ₁ , W ₂ ... W _n are each monomer i (i = 1, 2, ...
, N) represents the weight fraction in the polymer (B), Tg ₁ ,
Tg ₂ ..., Tg _n represent the glass transition temperature (° C.) of the polymer composed of each monomer i. The polymer (B) is added and mixed in the form of latex, coagulated slurry, dry powder, or the like. As the monomer forming the polymer (B), the same monomers as those forming the thermoplastic polymer (A) can be used.

The inorganic compound (C) used in the present invention is
An oxide of one or more elements selected from the group consisting of Si, Mg, Al, Ca, Ba, Zn and Ti,
Examples thereof include chlorides, hydroxides, carbonates and sulfates, or a mixture thereof. Specific examples thereof include SiO ₂ , MgO, Mg (OH) ₂ , MgCO ₃ , and A.
l ₂ O ₃ , Al (OH) ₃ , Al ₂ (CO ₃ ), CaO, C
Examples thereof include aCO ₃ , TiO ₂ , talc, clay, and diatomaceous earth calcium metasilicate.

The average particle size of the polymer (B) and / or the inorganic compound (C) depends on the particle size of the thermoplastic polymer (A), but is preferably 10 μm or less, more preferably 5 μm.
It is preferably m or less. If the average particle size exceeds 10 μm, the effect of modifying the surface of the particles of the thermoplastic polymer (A) is small, so that crushing after pressure compression becomes difficult. As the particle size of the polymer (B) and / or the inorganic compound (C) is smaller, the surface of the powder of the thermoplastic polymer (A) can be coated with a smaller amount, and the modifying effect is increased.

The amount of the polymer (B) and / or the inorganic compound (C) added is 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the thermoplastic polymer (A).
Parts by weight. If the addition amount is less than 0.1 parts by weight, it is difficult to crush after compression and compression described later and a good powder cannot be obtained, and if it is more than 10 parts by weight, the original amount of the thermoplastic polymer (A) is not obtained. It is not preferable because the physical properties change.

Next, pressure compression of the mixture will be described.
When the mixture after drying is pressure-compressed, voids inside the thermoplastic polymer (A) particles in the recovered mixture are eliminated and the inside is compacted. At the same time, the mixture becomes blocked. Since the surface of the particles of the thermoplastic polymer (A) is coated with the polymer (B) and / or the inorganic compound (C), the block can be easily crushed.

The temperature for compressing the mixture under pressure is (Tg
It is preferably in the range of (A) -30) to (Tg (A) +50) ° C. If it is performed at a temperature lower than (Tg (A) -30) ° C., the effect of improving the bulk specific gravity, which is the object of the present invention, is unlikely to be exhibited,
If the temperature is higher than (Tg (A) +50) ° C., the effect of the polymer (B) and / or the inorganic compound (C) will not be exhibited and crushing will be difficult, which is not preferable.

The pressurizing pressure is usually a surface pressure of 1000 kg / cm.
It is preferably about ² or less. When the pressure is high, the strength of the mixture in a block state increases and it becomes difficult to disintegrate, and it becomes difficult to obtain a good powder.

[0021]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by these examples. In addition, "part" in Examples and Comparative Examples
Represents "parts by weight".

Example 1 (1) Method for producing thermoplastic polymer (A-1) 1,3 Butadiene (Bd) 75 parts Styrene (St) 25 parts Divinylbenzene 1 part Ferrous sulfate 0.006 parts Sodium pyrophosphate 0.6 part Diisopropylbenzene hydroperoxide 0.4 part Dextrose 0.4 part Potassium oleate 1 part Deionized water 200 parts Each charge component of the above composition is charged into a pressure autoclave and stirred at 50 ° C. for 48 hours. A rubber latex was produced by reaction (polymerization rate 98%). After adding 1 part of sodium chloride to 70 parts (as solid content) of this rubber latex, a mixed monomer consisting of 13 parts of methyl methacrylate, 2 parts of ethyl acrylate and 0.045 part of cumene hydroperoxide and formaldehyde sodium sulfoxylate 0.06. Part was added, and the first stage graft polymerization was carried out at 70 ° C. for 2 hours. Then, in the presence of the polymer obtained in the previous step, styrene 1 was used as the second stage graft monomer.
After adding 5 parts and 0.06 parts of cumene hydroperoxide,
The second step graft polymerization was carried out at 70 ° C. for 3 hours to obtain a latex of the thermoplastic polymer (A-1) (solid content concentration 3
6% by weight, average particle size 0.115 μm).

(2) Method for producing polymer (B-1) Deionized water 280 was added to a reactor equipped with a stirrer and a reflux condenser.
Part, sodium dioctylsulfosuccinate 1 part, ammonium persulfate 0.2 part, methyl methacrylate 85 parts, butyl acrylate 15 parts, n-octyl mercaptan 0.
After a mixture of 02 parts was charged and the inside of the vessel was replaced with nitrogen, the temperature of the reaction vessel was raised to 65 ° C. with stirring, and the mixture was heated and stirred for 2 hours to polymerize to obtain a polymer (B-1) ( Solid content 2
7.8% by weight, average particle size 0.13 μm).

(3) Preparation of polymer powder 200 parts of the thermoplastic polymer (A-1) latex was placed in a container equipped with a 6-blade fan turbine type agitator.
Coagulation was performed using 600 parts of 0.23% dilute sulfuric acid. The polymer (B-1) was added to this slurry in a latex state. Then, after heating up to the solidification temperature shown in Table 1, dehydration drying was performed to obtain a powder. This powder was pressed and compressed at the temperature and pressure shown in Table 1 and then crushed to obtain a powder. The evaluation results are shown in Table 1.

Example 2 50 wt% of styrene, 40 wt% of butyl acrylate and 10 wt% of methyl methacrylate were emulsion polymerized to obtain a latex of a thermoplastic polymer (A-2) (solid content 3
3% by weight, average particle size 0.137 μm). Using the same apparatus as in Example 1, 200 parts of the thermoplastic polymer (A-2) latex was coagulated with 600 parts of 0.18% dilute sulfuric acid. Hydrophobic silica (B-2) (manufactured by Nippon Aerosil Co., Ltd., product number: R972, average particle size 0.0)
14 μm) was added. Then, after heating up to the solidification temperature shown in Table 1, dehydration drying was performed to obtain a powder. This powder was pressed and compressed at the temperature and pressure shown in Table 1 and then crushed to obtain a powder. The evaluation results are shown in Table 1.

Comparative Example 1 Except that the temperature at the time of compression and compression was carried out under the conditions shown in Table 1,
Treatment was carried out under the same conditions as in Example 2 to obtain a powder. The evaluation results are shown in Table 1.

Example 3 Deionized water 280 was added to a reactor equipped with a stirrer and reflux condenser.
Part, sodium dioctylsulfosuccinate 1 part, ammonium persulfate 0.2 part, methyl methacrylate 85 parts, butyl acrylate 15 parts, n-octyl mercaptan 0.
After a mixture of 02 parts was charged and the inside of the vessel was replaced with nitrogen, the temperature of the reaction vessel was raised to 65 ° C. with stirring, and the mixture was heated and stirred for 2 hours to polymerize to obtain a thermoplastic polymer (A-3). (Solid concentration 27.8% by weight, average particle size 0.13 μm). 200 parts of the thermoplastic polymer (A-3) latex was mixed with 0.
Coagulation was performed using 27% dilute sulfuric acid. Hydrophobic silica (B-2) was added to this slurry. Then, after heating up to the solidification temperature shown in Table 1, dehydration drying was performed to obtain a powder. This powder was pressed and compressed at the temperature and pressure shown in Table 1 and then crushed to obtain a powder. The evaluation results are shown in Table 1.

Example 4 The thermoplastic polymer (A-1) latex used in Example 1 was coagulated in the same manner as in Example 1. This slurry was solidified, dehydrated and dried in the same manner as in Example 1 to obtain a powder. Hydrophobic silica (B-2) was added to this powder,
Mixed. This powder was pressed and compressed at the temperature and pressure shown in Table 1 and then crushed to obtain a powder. The evaluation results are shown in Table 1.

Example 5 Deionized water 680 in a reactor equipped with stirrer and reflux condenser
Parts, dioctyl sodium sulfosuccinate 5 parts, ammonium persulfate 1.2 parts, methyl methacrylate 100 parts, n
-A mixture of 0.02 parts of octyl mercaptan was charged, the inside of the vessel was replaced with nitrogen, the temperature of the reaction vessel was raised to 65 ° C under stirring, and the mixture was heated and stirred for 2 hours to polymerize the polymer (B-3 Was obtained (solid content concentration 15% by weight, average particle size 0.05 μm).

The polymer (B-3) was added in a latex state to the slurry of the thermoplastic polymer (A-1) obtained in the same manner as in Example 1. Thereafter, in the same manner as in Example 1, solidification, dehydration and drying were performed to obtain a powder. This powder was pressed and compressed at the temperature and pressure shown in Table 1 and then crushed to obtain a powder. The evaluation results are shown in Table 1.

[0031]

[Table 1]

[0032]

According to the present invention, the bulk specific gravity of the thermoplastic polymer can be remarkably improved as compared with the case where a conventionally known method is used.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Wataru Hatano 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory

Claims (1)

[Claims] 1. A coagulated slurry of a thermoplastic polymer (A) having Tg (A) represented by the formula (X) obtained by emulsion polymerization, or a polymer powder obtained by drying the slurry, 0.1 to 10 parts by weight of the polymer (B) and / or the inorganic compound (C) are added to 100 parts by weight of the thermoplastic polymer (A) (Tg (A) -30) to (Tg).
(A) A method for producing a thermoplastic polymer powder, which comprises compressing the thermoplastic polymer (A) within a temperature range of +50) ° C. and then crushing it. Tg (A) = W ₁ × Tg ₁ + W ₂ × Tg ₂ + ... + W _n × Tg _n −− (X) [where n is the number of monomers forming the thermoplastic polymer (A)] And W ₁ , W ₂ ... W _n are each monomer i (i =
1, 2, represents the polymer (A) weight fraction in _{n), Tg 1, Tg 2} ···, Tg n is the glass transition temperature of the polymer composed of the monomer i (° C. ) Represents. ]