JP2000038454A - Production of rubber latex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing rubber latex for the production, for example, of high performance ABS resin substantially without generating aggregates at the expansion step even using rubber latex having a small particle size. SOLUTION: This method comprises adding an acid anhydride to small- particle rubber latex, which was obtained by emulsion polymerization and becomes unstable at acidic pH, having an average particle size of 150 nm or less at neutral or alkaline pH to expand the small-particle rubber latex to give rubber latex having a wide range of particle size, wherein the acid anhydride and the small-particle rubber latex are supplied into passing-through type tower mixer 8 to give a latex mixture, which is then introduced into container 6, thereafter the latex mixture is left for 10-300 min for sitting, then the resultant latex mixture is neutralized using a basic substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber latex having an average particle diameter of 150 to 400 nm having a wide particle diameter distribution suitable for producing an ABS resin by an industrially simple method.
The present invention relates to a method for producing a rubber latex obtained from a small particle rubber latex having a particle size of less than 150 nm without generating a coagulated product.

[0002]

2. Description of the Related Art ABS resins and ASA resins are prepared by mixing a monomer mixture comprising a vinyl cyanide monomer, an aromatic vinyl monomer and an unsaturated carboxylic acid ester monomer with a rubber-like polymer. A resin composition obtained by graft polymerization to
Due to its many features such as high impact resistance, high surface gloss, and good fluidity, it is widely used in the world.

[0003] The mechanical properties of the ABS resin depend on the properties of the rubbery polymer, the dispersed particle size and particle size distribution in the matrix resin, the amount of graft copolymerization on the rubbery polymer, the thickness of the graft layer, and the like. That is generally well known. In particular, the excellent impact resistance, which is a characteristic of ABS resins, is a property that fluctuates greatly due to these factors.
In order to obtain an ABS resin having excellent impact resistance, it is important to appropriately set these factors. From this point of view, various studies have been made on rubbery polymers suitable for use as ABS resin raw materials, and ABS resins developed based on these findings have been widely used as industrial materials.

[0004] Generally, the dispersed particle size of the rubber-like polymer used in the ABS resin is widely used in the range of 150 to 400 nm in average particle size from the viewpoint of impact resistance and appearance. . However, it takes a very long time to produce a rubbery polymer having such a particle size range by agglomeration by an emulsion polymerization method. In an effort to improve such low productivity, a relatively small rubbery polymer of less than 150 nm was prepared in advance and this was in some way reduced to an average particle size of 150 nm.
This is a technique called so-called enlargement, in which a rubber-like polymer having a size of about 400 nm is used.

Japanese Patent Publication Nos. 32-9592 and 33-4
No. 437 proposes enlargement by the freezing method, but the equipment required for the enlargement process becomes industrially enormous.
The problem is that the cost is likely to be very high. In addition, Japanese Patent Publication No. 37-10565 and 41-9
Nos. 82 and 60-19930 propose a method of enlarging a latex by applying a mechanical force such as a shearing force to the latex. There are problems such as difficulty in obtaining latex stably. In addition, the coagulated matter refers to a massive solid precipitated from rubber latex.

Further, Japanese Patent Publication Nos. 46-32056, 59-49937, and 62-61044 disclose a method of enlarging an acid by adding an acidic substance or an acid anhydride. This method is considered to be an industrially effective method with a relatively small amount of solidified material,
The resulting enlarged latex had a relatively narrow particle size distribution. However, such a rubber latex having a narrow particle size distribution has recently been demanded to be reduced in cost, and has been unsuitable for producing an ABS resin capable of satisfying diversified performance requirements.

JP-B-46-35976 discloses a method in which a monomer having an acid group is polymerized or copolymerized to obtain a latex, which is mixed with a rubber-like polymer latex to enlarge the composition. Although proposed, there is a problem that a relatively large amount of a rubbery polymer which does not enlarge remains and a desired particle size distribution cannot be obtained.

Further, Japanese Patent Publication No. Hei 7-21014 and Japanese Patent Application Laid-Open No. Hei 7-157502 propose a continuous enlarging method using a flow-type tubular device. However, there has been a problem that a rubber latex having a narrow particle diameter is obtained, and the particle diameter of a rubber latex that can be produced by using an acid as an acidic substance is limited, so that rubber latex having various particle diameters as required cannot be produced.

Further, as rubber latex used for the ABS resin, JP-A-9-249791 and JP-A-3-24979 are known.
Although it is possible to balance the impact resistance as proposed in Japanese Patent No. 288551, the moldability, which is one of the basic performances of the ABS resin, is deteriorated,
In many cases, it has a bad influence on coloring properties as proposed in Japanese Patent No. 278404, and it is preferable to use a rubber latex having a rather wide particle size distribution in order to produce an ABS resin applicable to a wide range of uses.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rubber for producing a rubber latex having a desired particle size distribution at a time with almost no coagulation during the process of enlargement by an industrially advantageous method. An object of the present invention is to provide a method for producing latex. The rubber latex as a raw material of the ABS resin or the like is often required to have a certain particle size distribution for practical use except for a specific case, and in particular, excellent impact resistance, which is a characteristic of the ABS resin, A wide particle size distribution was required to balance the fluidity-resin molding appearance with higher dimensions. In such a demand, a step of preparing a plurality of enlarged rubber latexes having different particle diameters in advance and blending them at a certain ratio is required, and from an industrial viewpoint, the production process becomes complicated and the equipment is increased. There are many issues such as inviting.

[0011]

The gist of the present invention is that an acid anhydride previously dispersed in an aqueous medium is mixed with small-particle rubber latex in a flow-type tubular device and introduced into a container at a low Reynolds number. After that, the mixture is allowed to stand for a certain period of time to allow the enlargement to proceed, and thereafter, through a neutralization step with a basic substance, finally obtains a rubber latex suitable for producing a high-performance ABS resin having a wide particle size distribution. It is characterized by the following. That is, the present invention provides a neutral or alkaline small particle rubber latex having an average particle diameter of 150 nm or less, which is unstable in an acidic region obtained by emulsion polymerization, and adding an acid anhydride to enlarge the small particle rubber latex. A method for producing a rubber latex for obtaining a rubber latex having a wide particle size distribution, wherein an acid anhydride and a small particle rubber latex are supplied into a flow-type tubular device and mixed to form a mixed latex, and the mixed latex is placed in a container. And then leaving the mixture to stand for 10 minutes or more and 300 minutes or less, and then neutralizing with a basic substance. In the production method, the time required from the start of introducing the mixed latex into the container to the end of the introduction is 5 minutes or more and 60 minutes or less, and most of the mixed latex discharged into the container is placed below the liquid level. And the mixed latex in the supply pipe which supplies the mixed latex into the container from the flow-type tubular device is in a laminar flow state having a Reynolds number of 2,000 or less,
The aqueous solution obtained by previously mixing the acid anhydride and water in the first-stage flow-type tubular device is supplied to the second-stage flow-type tubular device and mixed with the small-particle rubber latex. Ratio of particles having a weight average particle size S of 150 to 400 nm and having a particle size of less than 150 nm is less than 10% by weight and further having a particle size in the range of 0.8 × S to 1.25 × S. Is 70% by weight or less,
Are each preferred.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The small particle rubber latex used in the present invention has a need to promote the enlargement by adding an acid anhydride.
≦ 6), it is necessary to be an unstable one that causes aggregation or the like. For this purpose, neutral or alkaline (pH>
6).

The type of the emulsifier to be used is not particularly limited as long as the above-mentioned object is achieved. Examples thereof include fatty acid soaps such as sodium oleate, sodium stearate, sodium laurate, mixed fatty acid sodium, and potassium salts thereof. Rosin acid soaps represented by abietic acid salts and alkenyl succinates having an alkyl group having 6 to 15 carbon atoms can be used, and these can be used alone or in combination of two or more. Since the small particle latex can be easily obtained by emulsion polymerization, its use amount is preferably 0.5 to 5 parts by weight used for normal emulsion polymerization based on 100 parts by weight of the rubbery polymer.

The composition of the rubber-like polymer is not particularly limited as long as it exhibits rubber-like properties at normal temperature. For example, polybutadiene rubber, styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR) ) And acrylic rubbers such as polybutyl acrylate rubbers, and these may be used alone or in combination of two or more.

The weight average particle diameter of the small particle rubber latex is less than 150 nm, and if it exceeds 150 nm, the polymerization time is prolonged and not only the economical advantage which is one of the objects of the present invention is diminished, but also , Enlargement becomes difficult to progress.

[0016] The concentration of the small particle rubber latex has a great effect on the particle diameter of the enlarged particles and the amount of coagulated product. If the concentration is high, the diameter of the enlarged particles increases, and the amount of coagulated matter increases, and if the concentration is lowered, the reverse tendency is observed. Therefore, an appropriate concentration is selected, but a practically preferable range is 20 to 50% by weight of a small particle rubber latex. If the content is less than 20% by weight, a large amount of acid anhydride is required, and the enlarged latex becomes thin and the practical value is reduced. If it exceeds 50% by weight, a large amount of coagulated material is generated.

As a method for obtaining the small particle rubber latex, emulsion polymerization is selected from the viewpoint of ease of production. In addition, the initiator in the emulsion polymerization is not particularly limited, and "hot rubber" using ordinary potassium persulfate is used.
Formulas and so-called "cold rubber" formulas (redox formulas) using an organic peroxide, a reducing agent and a catalyst can be used.

The acid anhydride used in the present invention is not particularly limited as long as it is an anhydride of an organic acid.
Maleic anhydride, propionic anhydride, benzoic anhydride, glutaric anhydride, valeric anhydride, isovaleric anhydride, succinic anhydride, citraconic anhydride, itaconic anhydride and the like are preferred, and acetic anhydride or maleic anhydride is particularly preferred. It is.

The amount of the acid anhydride to be used is arbitrarily selected according to the particle size of the desired enlarged rubber latex. A rubber latex having a larger particle diameter can be obtained by using a large amount of the acid anhydride, and a rubber latex having a smaller particle diameter can be obtained by using a small amount of the acid anhydride.However, when the amount of the added acid anhydride is too small, The enlargement becomes difficult to progress, and the lower limit of the amount of the acid anhydride used is limited. Although it depends on the type of the acid anhydride, it is generally necessary to add 0.1 parts by weight or more to 100 parts by weight of the small particle rubber latex.

In order to uniformly disperse the acid anhydride in the small particle rubber latex, it is preferable to previously dissolve or disperse the acid anhydride in an aqueous medium. More preferably, it is preferable to mix the rubber latex in a state where the acid anhydride and water are uniformly mixed in advance in a flow tube type device (a state of an aqueous solution). The contents of the flow pipe type device here will be described later. Enlargement is possible without previously dissolving or dispersing the acid anhydride in an aqueous medium, but a large amount of coagulated material is generated. In addition, when the amount of water is too large to be a dilute acid anhydride aqueous solution, almost no coagulation is generated, but the enlarged latex is also diluted, which is disadvantageous in terms of production cost and practical value. Disappears. From the above, it is preferable to use 10 to 50 parts by weight of water per 1 part by weight of the acid anhydride.

FIG. 1 is a diagram showing an example of a production apparatus used in the method for producing a rubber latex of the present invention. As shown in FIG. 1, the manufacturing apparatus includes a water inlet 2 and an acid anhydride inlet 3.
An acid anhydride and water are mixed in advance to provide an aqueous solution,
The first-stage flow-type tubular device 9 for supplying the aqueous solution to the second-stage flow-type tubular device 8, and the inlet 1 for introducing the small-particle rubber latex are provided. The mixed latex is introduced into the container 6 by introducing the mixed latex into the container 6, and the mixed latex having the discharge port 5 and passing through the second-stage flowing tubular device 8. After supplying (supplying) a supply pipe 4 and the mixed latex introduced from the supply pipe 4 for 10 to 300 minutes, the small particle rubber latex is enlarged and the particle size distribution of the rubber latex is widened. A container 6 for neutralizing the latex with a basic substance.

The acid anhydride dispersed in the aqueous medium is intermittently or continuously supplied into the small-particle rubber latex using the second-stage flow-type tubular device 8. The shape of the flow pipe type device 8 is not particularly limited, but for example, a device as shown in FIG. 1 is preferable. In the illustrated apparatus, a small particle rubber latex is supplied from an inlet 1, and an acid anhydride previously dispersed in an aqueous medium is supplied to a mixing section A from an inlet 7. The small particle rubber latex and the acid anhydride previously dispersed in an aqueous medium are mixed in a second-stage flow-type tubular device 8 to form a mixed latex, and the mixed latex is supplied via a supply pipe 4 to an outlet 5. Is introduced into the container 6.

In the second-stage flow-type tubular device 8, there is a mixing element B which promotes mixing at part A where the small-particle rubber latex and the acid anhydride dispersed in the aqueous medium come into contact with each other. As an example of the mixing element B, a device for dynamically stirring such as an in-line mixer or a device for statically stirring such as a static mixer can be installed. 1 can be installed at various angles from horizontal to vertical. When the specific gravity of the rubber latex particles to be enlarged is larger than that of water, the inlet of the small particle rubber latex is set up to lower the small particle rubber latex, and when it is small, the small particle rubber latex It is preferred that the inlet of the rubber latex is set downward as shown in FIG. 1 so that the flow of the small particle rubber latex rises. In addition, like the mixing element B, an in-line mixer, a static mixer, or the like can be used as the mixing element D of the first-stage flow-type tubular device 9.

The rubber latex (mixed latex) thus mixed is transferred into the container 6 which is not stirred as it is. When transferred to the container 6, the discharge port 5 shown in FIG.
Is installed at a position such that most of the mixed latex is discharged below the liquid level of the rubber latex in the container 6.
The majority means that when the container 6 is empty, the discharge port 5 cannot be below the liquid level, so that 50% by weight or more, preferably 70% by weight or more of the total amount of the mixed latex.
Less than 0% by weight. If an amount exceeding 50% by weight of the total amount of the mixed latex is supplied above the liquid level, a large amount of coagulated material is generated.

Further, from an industrial point of view, the flow state of the mixed latex flowing in the supply pipe 4 shown in FIG. A so-called laminar flow state in which the Reynolds number in the pipe is 2000 or less is preferable. If the Reynolds number is in a turbulent state exceeding 2000, a large amount of solidified material is generated in the supply pipe 4, which is not preferable. Although any method may be used to adjust the Reynolds number of the mixed latex flowing in the supply pipe 4, a known method of changing the inner diameter of the pipe,
A method of adjusting the flow rate in the tube, a method of adjusting the viscosity of the mixed latex, and the like can be used.

When the mixed latex obtained by mixing the small particle rubber latex and the acid anhydride is transferred from the supply pipe 4 to the container 6 through the outlet 5, the acid anhydride is already dispersed in the rubber latex. Because the diffusion of the acid anhydride is promoted by the flow generated during the liquid transfer,
Agitation is not required during or after the liquid transfer, but rather, a large amount of coagulated material is generated due to the stirring. In addition, the time required from the start of the liquid transfer to the container 6 from the flow-type tubular device 8 to the end of the liquid transfer is determined according to the purpose of the present invention to obtain a rubber latex having a wide particle size distribution. Although it is affected by the holding time after the mixed latex is completely introduced, it is preferable to adjust the mixing time to 5 minutes or more and 60 minutes or less. When the time is less than 5 minutes, it becomes impossible to obtain a rubber latex having a desired wide particle size distribution,
The same is true even if the time exceeds 60 minutes. Although this mechanism is not well understood, the time from the start of mixing the acid anhydride and the rubber latex until the latex is stabilized by the basic substance, that is, the enlargement time, varies continuously or intermittently. It is presumed that a desired particle size distribution can be obtained by the above.

In the present invention, it is presumed that the acid anhydride is mixed into the small particle rubber latex and then hydrolyzed to enlarge the small particle rubber. Therefore, the acid anhydride depends on the hydrolysis rate of the acid anhydride. Holding time, that is, standing time. The holding time is closely related to the time required from the start to the end of the liquid transfer from the flow-type tubular device to the container 6 and varies to some extent depending on the type of the acid anhydride used, but usually 10 minutes. The time is at least 300 minutes, preferably at least 15 minutes and at most 200 minutes. If the holding time of holding the mixture of the acid anhydride and the small particle rubber latex in the container 6 without stirring is short, the progress of the enlargement becomes insufficient, and the diameter of the enlarged particle becomes small or 150 nm.
The number of small particles less than the above is increased, and the intended high-performance ABS resin cannot be obtained. On the other hand, when the time exceeds 300 minutes, the particle size distribution of the rubber latex becomes narrow, and a large amount of lumps are generated.

After being kept in the container 6 for a specific time, the enlarged rubber latex can be stabilized by adding a basic substance. Although any basic substance may be used, compounds such as sodium hydroxide, potassium hydroxide, ammonium hydroxide (aqueous ammonia), sodium carbonate and potassium carbonate can be used, and particularly preferred is sodium hydroxide. Or potassium hydroxide. These can be used in the form of an aqueous solution, the concentration of which is selected depending on the type of the substance, and an aqueous solution of about 1 to 10% by weight is used. If it exceeds 10% by weight, coagulated matter is liable to be generated, and if it is less than 1% by weight, the latex becomes too thin and the productivity deteriorates.

The expanded rubber latex has an average particle size of 15 for the purpose of being provided for the production of ABS resin.
A range from 0 to 400 nm is chosen. When the thickness is less than 150 nm or more than 400 nm, impact resistance and surface gloss, which are one of the basic performances of the obtained ABS resin, become low.

The particle size distribution of the rubber latex, which is the object of the present invention, is preferably such that the proportion of particles having a size of less than 150 nm is less than 10% by weight, preferably less than 7% by weight. If it exceeds 10% by weight, the performance of the ABS resin obtained by using the rubber becomes poor. Second, 0.8 × S to 1.25 × S (however, S
Is the weight average particle size of the manufactured rubber latex. ) Is 70% by weight of particles having a particle diameter in the range
Or less, more preferably 60% by weight or less. With a rubber latex having a narrow particle size distribution exceeding 70% by weight, it is impossible to produce an ABS resin applicable to a wide range of applications which is the object of the present invention.

The rubber latex having a specific particle size distribution obtained according to the present invention can be produced by using AB consisting of acrylonitrile-butadiene rubber-styrene.
The resin is not limited to S resin, and any resin may be used, but acrylonitrile-acrylic rubber-styrene (ASA) resin, methyl methacrylate-butadiene rubber-styrene (MBS) resin, high-impact polystyrene resin, and polycarbonate resin with these resins And a polymer alloy with a polyester resin and a polyamide resin.

[0032]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. The percentages and parts in the following examples mean% by weight and parts by weight unless otherwise specified. The particle diameter distribution of the rubber latex in the following Examples and Comparative Examples was such that ultra-dilute rubber latex droplets were placed on a copper mesh for a transmission electron microscope provided with a corrosion film, and this was dyed with osmium tetroxide. After that, the water was evaporated to dryness, photographed with a transmission electron microscope (magnification: 20,000 times), and the size of 300 to 500 rubber particles was counted and determined.

Production Example 1-Production of Small Particle Rubber Latex (A) In a 10-liter stainless steel autoclave equipped with a stirrer, 150 parts of deionized water (hereinafter simply referred to as water) styrene 10 parts Potassium oleate 1.5 parts Potassium rosinate 1.5 parts Potassium hydroxide 0.1 part Potassium persulfate 0.3 part was charged, the pressure was reduced after replacing with nitrogen, butadiene 90 parts was charged, the internal temperature was raised to 70 ° C, and polymerization was carried out for 10 hours. went. After removing the remaining butadiene monomer by steam distillation, the mixture was cooled to give an average particle size of 85 nm, a solid content of 40.1%,
A small particle rubber latex (A) having a pH of 11.0 was obtained.

Production Example 2-Small particle rubber latex (B)
In the example described in Preparation Example 1, 90 parts of butadiene was added to 5 parts of acrylonitrile instead of 10 parts of styrene.
The polymerization was carried out in the same manner except that the average particle diameter was changed to 8 parts.
A small particle rubber latex (B) having 0 nm, a solid content of 40.3% and a pH of 11.1 was obtained.

Production Example 3-Small particle rubber latex (C)
Production of 10L glass reactor with nitrogen replacement (with stirrer)
And 150 parts of water, 0.03 parts of sodium carbonate, 0.5 parts of dipotassium alkenylsuccinate, 0.3 parts of Rongalit, 0.00005 parts of ferrous sulfate heptahydrate, 0.00005 parts, and 0.00015 parts of disodium ethylenediaminetetraacetate. Warmed. 98.8 parts of n-butyl acrylate 0.9 parts of allyl methacrylate 0.3 parts of 1,3-butylene methacrylate 0.2 parts 0.2 parts of tert-butyl hydroperoxide 0.5 parts of dipotassium alkenyl succinate The resulting solution was added dropwise over 4 hours under a nitrogen flow.
A small particle rubber latex (C) having a solid content of 40.4% and a pH of 8.8 was obtained.

Example 1 The mixing element B shown in FIG. 1 has an inner diameter of 30 mm, a length of 250 mm, and the mixing element D has an inner diameter of 15 m.
m, a small-particle rubber latex (A) having an average particle diameter of 85 nm obtained in Production Example 1 was introduced from the inlet 1 at room temperature by using a two-stage flow-type tubular device 8 or 9 which was a static mixer having a length of 125 mm. After the liquid was fed at 100 ml / min and the inside of the tube 8 was filled with latex, water was supplied from the inlet tube 2 at a rate of 6 ml / min and acetic anhydride from the inlet 3 at a rate of 0.25 ml / min. A) and acetic anhydride were mixed by a flow tube type apparatus 8. The mixed latex obtained by this mixing was confirmed to be in a laminar flow state at a Reynolds number of 55 in a supply pipe 4 having an inner diameter of 8 mm, and a container 6 having a discharge port 5 5 mm above the bottom (capacity 5 L, no (Stirring). 40 minutes after the discharge to the container 6 starts, the introduction pipe 1
3 were simultaneously stopped, and all the remaining liquid in the tube was sent out into the container 6 as it was. After leaving the mixed latex in the container 6 for 10 minutes, 190 ml of a 4% aqueous sodium hydroxide solution was added, and after 5 minutes, the mixture was stirred and neutralized to adjust the pH of the latex to 11, thereby completing the enlargement.
The obtained latex was filtered with a gauze, and the obtained mass was dried and measured for weight. As a result, it was 0.15 g (0.01% based on the total polymer), which was good. The weight average particle size (S) was 320 nm, and the particle size distribution of the obtained enlarged latex was measured. As a result, the ratio of particles smaller than 150 nm was 3%, 256 nm (0.8 × S) to 400 nm.
42% of particles having a particle size in the range of (1.25 × S)
And had a broad particle size distribution.

Example 2 The same operation was performed except that the latex feed rate was 200 ml / min, all the latex was introduced into the container 6 in 20 minutes, and the standing time was 2 hours. Reynolds number at 4; 27), mass after drying is 0.0
8 g (0.005% based on the total polymer) was good.
The weight average particle diameter (S) was 320 nm, and the particle diameter distribution of the obtained enlarged latex was measured.
The ratio of particles less than m is 1%, 0.8 × S to 1.25 × S
Particles having a wide particle size distribution of 55%.

Example 3 A treatment was carried out in the same manner as in Example 1 except that the rubber latex used was changed to the small particle rubber latex (B) of Production Example 2 (Reynolds number in the supply pipe 4 at this time; 5
5) The mass after drying was as good as 0.20 g (0.013% based on the total polymer). Weight average particle size (S)
Was 270 nm, and the particle size distribution of the resulting enlarged latex was measured. As a result, 4% of the particles had a particle size of less than 150 nm, and 5% of the particles were in the range of 0.8 × S to 1.25 × S.
It had a particle size distribution as wide as 4%.

Example 4 A treatment was carried out in the same manner as in Example 1 except that the rubber latex used was changed to the small particle rubber latex (C) of Production Example 3 (Reynolds number in the supply pipe 4 at this time; 5
5) The mass after drying was as good as 0.10 g (0.006% based on the total polymer). Weight average particle size (S)
Was 340 nm, and the particle size distribution of the resulting enlarged latex was measured. As a result, 5% of the particles had a particle size of less than 150 nm, and 5% of the particles were in the range of 0.8 × S to 1.25 × S.
It had a particle size distribution as wide as 1%.

COMPARATIVE EXAMPLE 1 A small particle rubber latex (A) 4,0 was placed in a container 6 (volume: 5 L) using a device having an acid anhydride aqueous solution inlet 7 as an outlet 5.
Under stirring at 200 rpm, 230 g of water was introduced from the introduction pipe 2 and 9.6 g of acetic anhydride were respectively supplied and supplied from the introduction pipe 3 for 30 seconds. After completion of the supply, stirring was continued for 1 minute to stop stirring. 3 as it is
After allowing to stand for 0 minutes, 190 ml of a 4% aqueous sodium hydroxide solution was added to adjust the pH to 11. The mass after drying is 0.
08 g (0.005% based on the total polymer) was good. The weight average particle diameter (S) was 310 nm, and the particle diameter distribution of the obtained enlarged latex was measured.
3% of particles less than 0 nm, 0.8 × Sｎｍ1.25
The particles falling within the range of × S had a narrow particle size distribution of 84%.

Comparative Example 2 A treatment was carried out in the same manner as in Example 1 except that the standing time after the entire amount of latex was introduced into the container 6 was changed to 3 minutes (at this time, the Reynolds Number; 54),
0.03 g of a mass after drying (0.03
02%). Weight average particle size (S) of 17
0 nm, and the particle size distribution of the resulting enlarged latex was measured.
And there were very many.

Comparative Example 3 A treatment was carried out in the same manner as in Example 1 except that the standing time after the entire amount of the latex was introduced into the container 6 was changed to 8 hours (at this time, the Reynolds Number; 5
4) The mass after drying was as large as 82.5 g (5.16% based on the total polymer). The weight average particle size (S) was 390 nm, and the particle size distribution of the obtained enlarged latex was measured. As a result, the ratio of particles having a particle size of less than 150 nm was 1% by weight, 0.8 × S to 1.25 × S. The particles falling within the range had a narrow particle size distribution of 89%.

[0043]

As described above, according to the method for producing rubber latex of the present invention, even if rubber latex having a small particle diameter is used, hardly any coagulated material is generated in the enlargement step, and high performance ABS is obtained. It is possible to industrially produce an enlarged rubber latex having a wide particle size distribution suitable for production of a resin or the like.

[Brief description of the drawings]

FIG. 1 is an apparatus diagram showing an example of a production apparatus used in a method for producing a rubber latex of the present invention.

[Explanation of symbols]

1 ··· Small particle rubber latex inlet, 2 ··· water inlet, 3 ··· acid anhydride inlet, 4 ··· supply pipe, 5 ··· discharge pipe, 6 ··· container, 7 ··· acid anhydride Aqueous solution inlet, 8,
9 ··· Flow type tubular device, A, C · · · mixing section, B, D · · ·
Mixing element

Continued on the front page F term (reference) 4F070 AA04 AC40 CA05 CA19 CB01 CB13 FA05 FA08 FB05 FB06 FC01 4J002 AC031 AC071 AC081 BG041 EF126 EL136 EL146

Claims (5)

[Claims] 1. A neutral or alkaline average particle diameter of 150, which is unstable in an acidic region obtained by emulsion polymerization.
A method for producing a rubber latex in which an acid anhydride is added to a small particle rubber latex having a particle diameter of not more than nm to obtain a rubber latex having a large particle size distribution by adding an acid anhydride, wherein the acid anhydride and the small particle rubber latex are used. Is supplied into a flow-type tubular device and mixed to form a mixed latex. The mixed latex is introduced into a container and allowed to stand for 10 minutes or more and 300 minutes or less, and then neutralized with a basic substance. Method for producing rubber latex. 2. The method for producing a rubber latex according to claim 1, wherein the time required from the start of introducing the mixed latex into the container to the end of the introduction is from 5 minutes to 60 minutes. 3. A mixed latex in a supply pipe for discharging most of the mixed latex discharged into a container below the liquid level and supplying the mixed latex from a flow-type tubular device into the container has a Reynolds number of 2,000. The method for producing a rubber latex according to claim 1, wherein the method is in the following laminar flow state. 4. An aqueous solution obtained by previously mixing an acid anhydride and water in a first-stage flow-type tubular device is supplied to a second-stage flow-type tubular device and mixed with the small-particle rubber latex. A method for producing the rubber latex described above. 5. The rubber latex thus produced has a weight average particle size S of 150 to 400 nm, and the proportion of particles having a particle size of less than 150 nm is less than 10% by weight, and more preferably 0.8 × S to 1. The method for producing a rubber latex according to claim 1, wherein the proportion of particles having a particle diameter in the range of 25 x S is 70% by weight or less.