JP2000072882A - Production of powdery diene-based graft polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a powdery diene-based graft polymer having excellent powder characteristics from a latex by spray-drying safely and in excellent productivity. SOLUTION: A latex which is a diene-based graft polymer latex having 50 wt.% to 85 wt.% rubber content in the polymer and contains 0.1-2 pts.wt. of a hindered phenol-based stabilizer and 0.3-6 pts.wt. of a thioether-based stabilizer based on 100 pts.wt. of the diene-based graft polymer is spray-dried and powdered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a diene-based graft polymer, and more particularly, to industrially continuously produce a diene-based graft polymer suitable for an impact modifier of a vinyl chloride resin. The present invention relates to a method for producing a powdery diene-based graft polymer having excellent powder properties by spray-drying a latex produced by an emulsion polymerization process.

[0002]

2. Description of the Related Art Diene-based graft polymers represented by MBS (methyl methacrylate / butadiene / styrene) resins are widely used as impact modifiers for various plastic products such as vinyl chloride resins. An emulsion polymerization method is generally used as a method for producing these diene-based graft polymers. Since these diene-based graft polymers are melt-kneaded with a vinyl chloride resin powder, they need to be recovered as a dry powder. As a general method of this powdering,
There is known a so-called coagulation method in which latex is introduced into an aqueous solution of a coagulant such as inorganic salts and acids, or a coagulant is introduced into the latex.

However, the coagulation method has the following problems. 1. The process is huge and complicated, the equipment cost is high,
There is also a problem in terms of productivity. 2. It is difficult to control the particle diameter and the particle structure (shape), and the resulting powder generally has a wide particle size distribution, a low bulk specific gravity, and is poor in fluidity and blocking resistance due to its irregular shape. 3. Since the coagulant is used, the coagulant remaining in the powder adversely affects the physical properties of the vinyl chloride resin, particularly the thermal stability.

[0004] On the other hand, as a method for obtaining powder having excellent powder characteristics at low equipment cost, a method of spray-drying a polymer latex is known. The only example of spray-drying a latex of a diene-based graft polymer is disclosed in JP-A-63-1.
JP-A-56830 discloses spray drying of a graft copolymer latex obtained by graft-polymerizing styrene-butadiene rubber with α-methylstyrene, methyl methacrylate, and acrylonitrile. But,
The rubber content in the graft copolymer shown is 20% by weight. It is known that the higher the rubber content, the higher the impact modification effect of the impact modifier for the vinyl chloride resin. The impact modifier must be a diene graft polymer having a rubber content of 50% by weight or more. Not worthy of reforming.

The biggest problem in spray-drying a diene-based graft polymer is prevention of autoxidation of the diene-based polymer in the backbone polymer. Generally, a diene polymer has a property of causing a reaction such as autoxidation and igniting in the presence of oxygen and heat. In particular, when the spray drier is operated continuously, there is a considerable possibility that accumulated matter accumulates in the dryer and the accumulated matter is automatically oxidized, causing ignition and explosion. To shorten the staying time of debris, frequently wash the inside of the dryer,
Although it is necessary to remove the retentate, this operation significantly reduces productivity.

[0006] The higher the content of the diene polymer, the easier it is to be oxidized as well as the more likely it is for the resin to stay in the dryer. Therefore, the high content of the diene polymer has a double adverse effect on the problem of autoxidation of the retentate. Will be exerted. That is, it is difficult to safely and continuously produce a diene-based graft polymer having a high rubber content by the method described in JP-A-63-156830.

[0007] For example, Japanese Patent Publication No. 61-42923 discloses a method in which latex is sprayed into a coagulation chamber in a coagulation atmosphere, and the agglomerated particles that have fallen are collected in a collection liquid at the side wall or bottom of the coagulation chamber. However, this method also employs a method of recovering in a liquid, and has not yet reached the point of spray drying.

[0008]

As described above, a method for obtaining a diene-based graft polymer having excellent powder properties by spray-drying a diene-based graft polymer latex with good safety and productivity is still known. Did not.

The present invention has been made in view of the above problems, and provides a method for spray-drying a powdery diene-based graft polymer having excellent powder properties from latex with good safety and productivity. The purpose is to do.

[0010]

The present invention relates to a diene-based graft polymer latex having a rubber content of 50 to 85% by weight in a polymer, wherein the latex is based on 100 parts by weight of the diene-based graft polymer. 0.1 to 2 parts by weight of a hindered phenol-based stabilizer and 0.0
The present invention relates to a method for producing a powdery diene-based graft polymer, comprising spray-drying a latex containing 3 to 6 parts by weight to powder.

The present inventors have analyzed the autoxidation mechanism and oxidation rate of the diene-based graft polymer in air, and found that by adding the above-mentioned predetermined amounts of the hindered phenol-based stabilizer and the thioether-based stabilizer, Fixed time M
The inventors have clarified that the oxidation of the BS resin is prevented, and have reached the present invention. According to the present invention, a diene-based graft polymer latex can be spray-dried safely and continuously for a long period of time, and as a result, a powdery diene-based graft polymer having excellent powder properties can be obtained with high productivity. Now you can.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a diene-based graft polymer is a butadiene-based polymer as a trunk polymer.
There is no particular limitation as long as a branched polymer is formed by graft-polymerizing a hard resin component monomer such as methyl methacrylate or styrene.

Here, the butadiene-based polymer includes polybutadiene and a butadiene-styrene copolymer having a butadiene unit content of 40% by weight or more, preferably 60% by weight or more. It is particularly preferable that the hard resin component monomer unit constituting the branch polymer has a methyl methacrylate unit and / or a styrene unit as a main component, and it is preferable that the monomer unit be contained, for example, at least 80% by weight in the branch polymer. The ratio of the methyl methacrylate unit to the styrene unit is, for example, 30:70 to 90:10 by weight. Other alkyl methacrylates, alkyl acrylates,
One or more monomer units such as an aromatic vinyl compound and a vinyl cyanide compound can be contained by graft copolymerization.

In the present invention, the rubber content in the diene-based graft polymer is the content of the butadiene-based polymer in the diene-based graft polymer, and the amount is 50 to 85% by weight.

A diene-based graft polymer having a rubber content of less than 50% by weight has poor performance as an impact modifier. In addition, the present invention can perform spray drying safely and with good productivity even when used for a diene-based graft polymer in which autoxidation easily occurs, so that the effect of the present invention is most exhibited when the rubber content is 50% by weight or more. You get. Rubber content 85% by weight
When it exceeds, adhesion to the inner wall of the dryer during spray drying becomes remarkable, and continuous operation becomes difficult, which is not always preferable.

The diene-based graft polymer latex used in the present invention is produced by emulsion polymerization. The emulsion polymerization method and emulsion polymerization conditions at that time are not particularly limited, and can be carried out under conventionally known methods and conditions. it can. Preferably, from the viewpoint of latex stability during spray drying,
First, it is preferable to polymerize a polybutadiene or butadiene-styrene copolymer latex as a core, and then perform graft polymerization of methyl methacrylate and styrene on the core in one step or two or more steps.

In the present invention, it is essential to add a hindered phenol-based stabilizer and a thioether-based stabilizer to the diene-based graft polymer latex before spray-drying. These additions prevent the oxidation of the diene-based graft polymer and its retentate in the spray dryer for a certain period of time, and enable continuous spray drying.

In the present invention, the hindered phenol-based stabilizer is a compound in which a bulky group is present at the ortho-position of the --OH group of the phenolic compound and which masks the properties of the phenolic --OH group. Examples include 2,6-di-tert-butyl-4-methylphenol,
2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-
Thiobis (3-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, n-
Octadecyl-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate, tetrakis [methylene-3 (3', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate ] Methane, triethylene glycol-bis [3- (3
-Tert-butyl-5-methyl-4-hydroxyphenyl) propionate], and pentaerythrityltetrakis [3- (3,5-di-tert-butyl-4)
-Hydroxyphenyl) propionate], and n-octadecyl-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate and triethylene glycol-bis [3-
(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred.

In the present invention, the amount of the hindered phenol stabilizer added to the latex is 0.1 to 2 parts by weight based on 100 parts by weight of the diene graft polymer. Preferably 0.2 to 100 parts by weight of the polymer
0.7 parts by weight. If the addition amount is less than 0.1 parts by weight, the period of antioxidation becomes short, and it becomes necessary to frequently clean the inside of the spray dryer. Further, even if it is added in excess of 2 parts by weight, it is not possible to obtain a productivity improvement effect that is commensurate with the increase in raw material costs.

In the present invention, the thioether-based stabilizer is a stabilizer having sulfide-s-, and specific examples thereof include 3,3'-thiodipropionic acid and dialkyl 3,3'-thiodipropionate. Pentaerythrityl-tetrakis (3-alkylthiopropionate), tetrakis [methylene-3- (alkylthio) propionate] methane, and bis [2-methyl-4 {3-alkyl-thiopropionyloxy} -5-tertiary Butylphenyl] sulfide, and dialkyl 3,3′-thiodipropionate and tetrakis [methylene-3- (alkylthio) propionate] methane are particularly preferred.

In the present invention, the amount of the thioether-based stabilizer to be added to the polymer latex is 100
The amount is 0.3 to 6 parts by weight, preferably 0.6 to 2 parts by weight based on parts by weight. If the addition amount is less than 0.3 parts by weight, the period of antioxidation becomes short, and it becomes necessary to frequently clean the inside of the spray dryer. Further, even if it is added in excess of 6 parts by weight, it is not possible to obtain a productivity improvement effect commensurate with an increase in raw material costs.

In the present invention, the amount ratio of the hindered phenol-based stabilizer to the thioether-based stabilizer is not particularly limited, but it is preferable to add the thioether-based stabilizer in an amount of 2 to 3 times the hindered phenol-based stabilizer. . Also,
It is also possible to use the above two kinds of stabilizers in combination with other antioxidants such as phosphite-based stabilizers.

The method for adding the hindered phenol-based stabilizer and the thioether-based stabilizer is not particularly limited as long as they are added to the latex before spray drying. For example, it is preferable that the above-mentioned stabilizer is emulsified and dispersed at the same time, or separately emulsified and dispersed, and then added at the end of the polymerization of the graft copolymer latex.

In the spray drying of the present invention, the latex is sprayed in the form of fine droplets and dried by blowing hot air on the latex. In this case, the continuous operation time of the spray dryer is determined by the formula (1).
It is preferable to operate continuously within a range not exceeding t (time) determined in (1). t = 7.8 × 10 ⁻²⁰ × exp {21540 / (273 + T−20)} × P × S (Equation 1) where t is the continuous operation possible time (hour), and T is the hot air of the spray dryer. Inlet temperature (° C.), P is the amount of hindered phenol-based stabilizer (parts by weight; based on 100 parts by weight of diene-based graft polymer), S is the amount of thioether-based stabilizer (parts by weight; 100 parts by weight of diene-based graft polymer) Part).
Note that P and S are respectively 0.1 ≦ P ≦ 2 and 0.3 ≦ S ≦
The range is 6.

In other words, as long as the time does not exceed t (time) in (Equation 1), continuous spray drying can be performed safely, and there is no need to perform cleaning work in the spray dryer during that time. If the spray drier is continuously operated for more than t (time) in (Equation 1), ignition and explosion may be caused by oxidation of the diene-based graft polymer.

Further, after the continuous operation for a time not exceeding the above-mentioned t (time), it is particularly preferable to wash the inside of the spray dryer and remove the residue. After the continuous operation, the operation is restarted without removing the long-term residue in the spray dryer, and if the total operation time exceeds the above (Equation 1), ignition and explosion occur due to oxidation of the diene-based graft polymer. there is a possibility.

Further, the temperature of the hot air introduced into the spray dryer (hot air inlet temperature), that is, the maximum temperature of the hot air capable of contacting the powdered diene graft polymer is preferably 200 ° C. or less.
At a temperature exceeding 200 ° C., the continuous operation time becomes short, and the productivity may be reduced.
40 ° C to 180 ° C.

The spray dryer used in the present invention is not particularly limited, and a known dryer can be used. As for the spraying device, a rotating disk type atomizer, a pressure nozzle type atomizer, a two-fluid nozzle type atomizer and the like can be used. The latex to be spray-dried may be used alone,
It may be a mixture of a plurality of latexes. A single spray nozzle or a plurality of spray nozzles can be used.

As the gas used for the drying medium, ordinary air can be used, and it is not particularly necessary to use a gas having a reduced oxygen content.

Further, in the present invention, it is preferable to simultaneously add an inorganic filler such as silica, talc and calcium carbonate or a hard resin such as a polymer of methyl methacrylate or styrene and a copolymer thereof during spray drying. . This makes it possible to reduce the adhesion and stagnation on the inner wall of the dryer.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
In the Examples and Comparative Examples, “parts” and “%” represent “parts by weight” and “% by weight”, respectively, unless otherwise specified.

Various evaluations in Examples and Comparative Examples were performed by the following methods. (1) Evaluation of powder characteristics (Example 1, Comparative Example 1) As a spray dryer, a large spray drier (straight body height 8 m, straight body inner diameter 1.6 m, pressurized two-fluid nozzle) was used. Hot air inlet temperature 150 ° C, latex flow rate 53kg /
hr, operating at an outlet temperature of 85 ° C.

The particle size distribution is measured by Japanese Industrial Standards (JIS
No. 408) using an evaluation device. The bulk specific gravity of the polymer particles was measured according to JIS-K
The flowability of the particles was measured based on -6721 (unit: g / cm ³ ). The fluidity of the particles was measured by putting 80 g of the polymer particles into the bulk density meter, removing the damper, and discharging the particles per unit time (unit: g / sec). .) Was measured. (2) Evaluation of spray drying continuous operation (Examples 2 to 10 and Comparative Examples 2 to 8) In consideration of safety, spray drying was performed using a small spray dryer (manufactured by NIRO JAPAN Co., Ltd .;
8m, inner diameter 1.5m, rotating disk atomizer)
And at a hot air inlet temperature of 140 to 210 ° C. Air was used as hot air for drying.

Regarding the continuous operation of spray drying, the residue in the spray dryer after the continuous operation was visually observed. (3) Measurement of Izod impact strength of polyvinyl chloride resin (Example 11, Comparative Example 9)
After kneading at 85 ° C. and press-molding at 50 kg / cm ² and 185 ° C., the measurement was performed according to ASTM D-256.

[Example 1] (Evaluation of powder properties of spray-dried diene-based graft polymer) (1) Synthesis of butadiene-based polymer latex The following initial materials were charged into a 70 L autoclave (practical pressure: 0.6 MPaG). Raise the temperature while stirring, 43
At the point where the temperature reached ° C, the following catalyst was charged into the reactor. Thereafter, the temperature was raised to 70 ° C., and the following additional emulsifier was continuously added over a period of 0.5 to 1.5 hours from the start of polymerization, and the following 2.5 hours, 3.0 hours, and 3.5 hours after the start of polymerization Additional initiator was added. Thereafter, when the polymerization conversion reached 97%, the polymerization was terminated. The solid content of the obtained butadiene polymer latex was 40%.

<Initial charge> 1.3 butadiene 74 parts Styrene 26 parts Na pyrophosphate (anhydrous) 0.12 parts Paramenthane hydroperoxide 0.3 parts Potassium tallowate 0.2 parts Deionized water 135 parts <Catalyst> Ferrous sulfate 0.003 part Hydrous crystalline glucose 0.2 part Deionized water 5.0 parts <Additional emulsifier> Potassium tallowate 2.2 parts Deionized water 10 parts <Additional initiator (3 times)> Paramenthan hydro Peroxide 0.3 part each (2) Synthesis of graft copolymer latex The following grafting raw materials were charged into a reactor, and after purging with nitrogen, 0.3 parts of sodium formaldehyde sulfoxylate was added, and the internal temperature was increased to 70%. The temperature was raised to ° C. afterwards,
The following first-stage graft monomer was continuously added over 60 minutes. Then, after holding for 80 minutes, the following second-stage graft monomer was continuously added over 90 minutes. Thereafter, after holding for 120 minutes, the following third-stage graft monomer was continuously added over 20 minutes, and the polymerization was terminated by holding for 120 minutes.

<Graft raw material> Butadiene rubber polymer latex 465 parts (solid content 186 parts) Deionized water 20 parts Potassium tallowate 2.0 parts <First stage graft monomer> Methyl methacrylate 28.8 parts Ethyl Methacrylate 7.2 parts t-butyl hydroperoxide 0.14 parts <second stage graft monomer> styrene 54 parts t-butyl hydroperoxide 0.21 part <third stage graft monomer> methyl methacrylate 10 parts t-butyl hydroperoxide 0.04 parts Triethylene glycol-bis [3- (3-tert-butyl) was added to the obtained graft copolymer (rubber content: 65%) latex and 100 parts of the graft copolymer. −
5-methyl-4-hydroxyphenyl) propionate]
Was added and emulsified and dispersed in 0.61 part of dilauryl 3,3'-thiodipropionate, followed by spray drying with a large spray dryer. At the same time, silica (Aerosil R972) was continuously added from the hot air inlet at a ratio of 0.05 part to 100 parts of the polymer. The bulk specific gravity of the obtained dry powder is 0.52 g / cc, and the fluidity is 4.3 g.
/ Sec, and the particle size distribution is such that particles having a size of 300 μm or more are 1.0
%, Particles of 38 μm or less were extremely sharp, 3.5%.

Comparative Example 1 (Evaluation of Powder Properties of Coagulation Method MBS) In this comparative example, the graft copolymer latex obtained in Example 1 was pulverized by a coagulation method, and the powder properties were examined. .

As the coagulation tank, a continuous tank type coagulation process consisting of a coagulation tank, one solidification tank and two solidification tanks in total was used.

The coagulation tank was a 3-liter overflow Pyrex glass round bottom flask having an inner diameter of 180 mm, a three-way swept wing having a wing diameter of 120 mm (Fautler wing),
One baffle having two rods of the same diameter and a length of 40 mm attached to the lower part of the rod at a 75-degree angle to the upper part of the rod at the lower part of the rod is 130 clockwise from the upper surface of the tank starting from the overflow port.
The one attached at a degree angle was used. Following one solidification tank,
The two solidification tanks (made by Pyrex glass, 5 liter overflow: inner diameter 180 mm) used the stirring blade used for the coagulation tank and the baffle set in the same manner as the coagulation tank.

For the coagulation experiment, a 1.44% aqueous sulfuric acid solution (DS
Using A), set the temperature of each tank to coagulation tank / solidification 1 tank / solidification 2
Vessel = 30/80/90 ° C., the above polymer latex was stirred at 150 rpm / min while stirring the coagulation vessel at 400 rpm, the solidification vessel was stirred at 300 rpm, and the DSA was stirred at 300 rpm.
To 60 ml / min [latex / DSA weight ratio = 2.5 /
1 (polymer solid content concentration in the coagulation tank 27.5%)], and the mixture was dropped and coagulated in the coagulation tank. After the inside of the coagulation tank was in a steady state, the coagulation liquid slurry was sampled from the outlet of the coagulation 2 tank.

The obtained coagulated liquid slurry was subjected to a dehydration treatment (1800) using a centrifugal dehydrator (Tanabe upper discharge type O-20).
(rpm: 3 minutes), and then dried using a batch-type fluidized drier set to a hot air temperature of 70 ° C. The bulk specific gravity of the obtained dry powder is 0.33 g / cc, and the fluidity is 2.9 g / c.
c, the particle size distribution is such that 45.0% of particles having a size of 300 μm or more,
Particles having a size of 38 μm or less were as broad as 1.5%.

[Examples 2 to 8 and Comparative Examples 2 to 7] (Evaluation of continuous operation for spray drying) The graft copolymer latex used in Example 1 was prepared as shown in Table 1.
And the amount of the hindered phenol-based stabilizer and the thioether-based stabilizer shown in Table 1 were emulsified and dispersed, and spray-dried using a small spray dryer under the conditions shown in Table 1. At the same time, the silica (Aerosil R
972) was continuously added at a ratio of 0.05 part to 100 parts of the polymer. Table 2 shows the results of observation of the residue in the spray dryer after the continuous operation.

Example 9 (Rubber content: 75%; evaluation of continuous operation of spray drying) In this example, continuous operation of spray drying was evaluated when the rubber content in the diene-based graft polymer was increased.

That is, in the synthesis of (2) graft copolymer latex of Example 1, the graft copolymer (rubber) was prepared in the same manner as in Example 1 except that <raw material for graft> was changed as follows. (Content: 75%) A latex was obtained. Butadiene rubber polymer latex 750 parts (solid content 300 parts) Deionized water 10 parts Potassium tallowate 1.5 parts Next, the same procedure as in Example 2 was carried out except that this graft copolymer (rubber content 75%) latex was used. The spray drying continuous operation was evaluated in exactly the same manner. Table 2 shows the results of observation of the residue in the spray dryer after the continuous operation.

[Example 10] (No silica added; evaluation of continuous operation of spray drying) Evaluation of continuous operation of spray drying was performed in exactly the same manner as in Example 2 except that silica (Aerosil R-972) was not added during spray drying. Was done. Table 2 shows the results of observation of the residue in the spray dryer after the continuous operation.

[Comparative Example 8] (Rubber content: 90%; evaluation of continuous operation for spray drying) Except for changing the <grafting raw material> in the synthesis of the graft copolymer latex of Example 1 as follows: In the same manner as in Example 1, a graft copolymer (rubber content 90%) latex was obtained. Butadiene rubber polymer latex 2250 parts (solids content 900 parts) Deionized water 0 parts Potassium tallowate 1.0 part Next, Example 2 except that this graft copolymer (rubber content 90%) latex was used. The spray-drying continuous operation was started in exactly the same manner as described above, but the continuous operation was stopped after about 5 hours because the powder was strongly attached to the wall surface and the bottom and the recovery rate of the product was extremely reduced.

Example 11 (Evaluation of Impact Resistance) 100 parts of polyvinyl chloride resin having an average degree of polymerization of 700, 12 parts of the MBS powder obtained in Example 1, 3 parts of dioctyltin mercaptide as a stabilizer and a lubricant, METABLEN P-55
0 (Mitsubishi Rayon Co., Ltd.) 2 parts, Metablen P-71
0 (manufactured by Mitsubishi Rayon Co., Ltd.) and 1 part of each component were mixed with a Henschel mixer until the temperature reached 110 ° C. for 10 minutes to obtain a polyvinyl chloride resin composition. Impact resistance (Izod impact strength) of a molded article molded using the obtained resin composition
Was 90 kg-cm / cm ² .

[Comparative Example 9] (Example in which rubber content was 30%, impact resistance evaluation) The procedure was the same as in Example 1 (2), except that the raw materials for grafting were changed as follows in the synthesis of the graft copolymer latex. In the same manner as in Example 1, a graft copolymer (rubber content 30%) latex was obtained. Butadiene rubber polymer latex 110 parts (solid content 43 parts) Deionized water 140 parts Potassium tallowate 1.5 parts Example 1 was repeated except that this graft copolymer (30% rubber content) latex was used. Just like MB
S powder was obtained.

Further, a polyvinyl chloride resin composition was obtained in exactly the same manner as in Example 11 except that this MBS powder was used. As a result of measuring the impact resistance (Izod impact strength) of a molded article molded using the obtained resin composition, 1
It was 5 kg-cm / cm ² .

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

According to the present invention, it has become possible to provide a method for spray-drying a powdery diene-based graft polymer having excellent powder properties from latex with good safety and productivity.

Continued on the front page (72) Inventor Koji Matsumura 20-1, Miyukicho, Otake City, Hiroshima Prefecture Inside Mitsubishi Rayon Co., Ltd. Otake Works (72) Inventor Hideaki Makino 20-1, Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Inside the Ohtake Works (72) Inventor Akira Nakata 20-1, Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Inside the Ohtake Works (72) Haruki Sato 20-1, Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayo 4F070 AA07 AA08 AB08 AC16 AC22 AC23 AC37 AC50 AC76 AC83 AE01 AE03 DA34 DA60 4J002 BC032 BG062 BN161 DE238 DJ018 DJ048 EJ016 EJ026 EJ036 EJ046 EV047 EV067 EV076 EV077 FD01877076

Claims (6)

[Claims] 1. The rubber content in a polymer is from 50% by weight to 85% by weight.
A diene-based graft polymer latex in an amount of 0.1 to 2 parts by weight of a hindered phenol-based stabilizer and 0.3 to 6 parts by weight of a thioether-based stabilizer with respect to 100 parts by weight of the diene-based graft polymer. A method for producing a powdery diene-based graft polymer, comprising spray-drying a latex containing parts by weight to powder. 2. The method for producing a powdery diene-based graft polymer according to claim 1, wherein the hot air inlet temperature of the spray dryer used for spray drying is 200 ° C. or lower. 3. The diene graft polymer according to claim 1, wherein the continuous operation time of the spray dryer used for spray drying does not exceed t (time) determined by the formula (1). Production method. t = 7.8 × 10 ⁻²⁰ × exp {21540 / (273 + T−20)} × P × S (Equation 1) (where, t: continuous operation possible time (hour), T: spray dryer) Hot air inlet temperature (° C), P: hindered phenol-based stabilizer (parts by weight), provided that 0.1 ≦ P ≦ 2, S: amount of thioether-based stabilizer (parts by weight), provided that 0.3 ≦ S ≦ 6 is there.) 4. The spray dryer according to claim 1, wherein said spray dryer is used for spray drying.
The method for producing a diene-based graft polymer according to claim 3, wherein after the continuous operation for not more than (hour), the inside of the dryer is washed to remove the retained matter before the next continuous operation. 5. The diene according to claim 1, wherein an inorganic filler or a hard resin is further added to the diene-based graft polymer latex to be spray-dried, followed by spray-drying. A method for producing a graft polymer. 6. The polymer in the diene-based graft polymer latex having a rubber content of 50% by weight to 85% by weight,
The method for producing a diene-based graft polymer according to any one of claims 1 to 5, wherein a monomer unit constituting the branch polymer has a methyl methacrylate unit and a styrene unit as main components.