JP5139195B2 - Method for producing rubber-reinforced styrene resin - Google Patents

Description

The present invention relates to a method for producing a rubber-reinforced styrene resin . Specifically, the present invention relates to a method for producing a rubber-reinforced styrene resin for enhancing the antioxidant function of the rubber-reinforced styrene resin .

  Rubber reinforced styrene based on names such as HIPS based on polybutadiene rubber, ABS resin, MBS resin, ABSM resin, AAS resin based on acrylic rubber, AES resin based on ethylene / propylene rubber Resins have an excellent balance between mechanical properties and processability, and are used in a wide range of fields such as vehicles, light electrical appliances, and OA equipment.

  As methods for producing these rubber-reinforced styrene resins, emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, and combinations thereof are known, but styrene in the presence of a rubber component, or A method of emulsion polymerization of styrene and monomers such as acrylonitrile and methyl methacrylate is frequently used. The rubber-reinforced styrene resin latex polymerized by emulsion polymerization is traded in powder or pellets through salting out, recovery, drying, or granulation processes, and then molded into vehicle parts, electrical parts, etc. The As described above, the rubber-reinforced styrene-based resin is exposed to high temperatures not only in the production process but also in the subsequent use. Therefore, the rubber component is susceptible to deterioration, particularly oxidative deterioration, leading to a decrease in mechanical strength. It is a factor.

For this reason, conventionally, such rubber-reinforced styrene-based resins are blended with phenol-based, sulfur-based, phosphorus-based, and amine-based antioxidants alone or in combination. In particular, phenol-based stabilizers have been sterically hindered (hindered) and / or made higher in molecular weight in order to meet higher requirements.

For example, a method has been disclosed in which a hindered phenol stabilizer having a melting point of 115 ° C. and a dispersing agent and casein are used in a ball mill for 6 hours to form a dispersion. However, it takes a long time for dispersion and is inferior in standing stability. Therefore, when blended in a resin latex , there is a problem that the stabilizer is separated.

  A product obtained by butylating a reaction product of paracresol and dicyclopentadiene, which is introduced in Patent Document 1 (Japanese Patent Application Laid-Open No. 11-217483), is also a high molecular weight and high melting point phenol-based stabilizer. Because it is difficult to make an emulsion, it is added and blended as a solid when mixing and granulating the graft copolymer obtained by salting out (condensing) the emulsion polymer and the copolymer pellets by the bulk polymerization method. However, oxidative deterioration in the salting out and drying steps of the graft copolymer cannot be prevented.

On the other hand, liquid products of the above-mentioned specific phenol-based stabilizers are industrially produced and sold as stabilizers for blending resin latex, but are dispersions with large particles. For this reason, there is a problem that the storage stability of the dispersion is poor and it is easy to separate. For example, K-840 manufactured by Chukyo Yushi Co., Ltd. has a large weight average particle size of 1.17 microns and less than 0.2 microns: 0%, 0.2 to 0.5 microns: 20.7%, 0.5 -1.0 micron: 2.9%, 1.0-10 micron: 33.8%, 10-20 micron: 0.0%, 20-30 micron: 19.0%, 30-40 micron: 1. It has a 6% particle size distribution and many large particles. For this reason, even when blended with a latex of a rubber-reinforced styrene resin that is generally 0.2 to 0.5 microns, the uniform dispersibility is inferior, and the stabilizer must be separated or excessively added.
JP-A-11-217483

The object of the present invention is not only to provide a low particle diameter emulsion containing a high melting point phenol-based stabilizer, but also excellent dispersibility in rubber-reinforced styrene resin (graft or / and copolymer) latex , And minimizing the amount required.

The inventors of the present invention not only improve the standing stability of the emulsion itself by setting the emulsified particles of the high-melting phenol-based stabilizer emulsion to a specific particle diameter, but also improve the stability of the emulsion to the rubber-reinforced styrene resin latex . The present inventors have found that it is excellent in dispersibility and can minimize the required addition amount.

That is, the present invention is a phenol-based stabilizer emulsion composed of a phenol-based stabilizer having a melting point of 90 ° C. or higher and, if necessary, another stabilizer and an emulsifier, and has a weight average particle size of 0.1. After adding a phenol-based stabilizer emulsion containing ˜1.0 microns and 70% or more of all particles to 1.0 microns or less to the rubber-reinforced styrene-based resin latex and uniformly dispersing in the latex, The present invention provides a method for producing a rubber-reinforced styrene resin through a salting-out step .

The phenol-based stabilizer emulsion of the present invention is excellent in standing stability, is excellent in addition efficiency, and exhibits a great antioxidant effect when used in a small amount. For this reason, it can utilize suitably for production of a rubber reinforced styrene resin as an antioxidant emulsion.

As a phenol-based stabilizer having a melting point of 90 ° C. or higher used in the present invention, a product obtained by butylation of a reaction product of p-cresol and dicyclopentadiene (melting point: 115 ° C., average molecular weight: 600 to 700), 4,4′-thiobis-3-methyl-6-tert-butylphenol (melting point 160 ° C., molecular weight 359), 4,4′-butylidenebis-3-methyl-6-tertiarybutylphenol (melting point 209 ° C., molecular weight 383), 2,2′-methylenebis-4-methyl-6-tert-butylphenol (melting point: 128 ° C., molecular weight: 341), and the like can be used, and one or more can be used. In particular, a phenol-based stabilizer having an average molecular weight of 500 or more is preferable. For example, a product obtained by butylation of a reaction product of p-cresol and dicyclopentadiene (for example, Good
Year: product name “Wingstay L”).

  In addition, the stabilizer emulsion of the present invention contains other stabilizers together with the above-mentioned phenolic stabilizers, such as conventionally known sulfur stabilizers, phosphorus stabilizers, amine stabilizers, and other (low melting point). A phenol-based stabilizer can be blended, and among these, a sulfur-based stabilizer is particularly preferable.

Examples of sulfur stabilizers include dilauryl-3,3′-thiopropionate, dimistil-3,3′-thiopropionate, distearyl-3,3′-thiopropionate, and pentaerythryltetrakis-3. -Lauryl thiopropionate, ditridecyl-3,3'-thiopropionate, 2-mercaptobenzimiazole, 2-tetrabutyl 6-3-tert-butyl-2-hydroxy-5-methylbenzoyl-4-methylphenyl Examples include acrylate, 2-1-2-hydroxy-3,5-ditertiarypentylpenylethyl-4,6-ditertiarypentylpenyl acrylate, and one or more of them can be used. In particular, dilauryl-3,3′-thiopropionate is preferred.
Examples of the phosphorus-based stabilizer include trisnolylphenyl phosphite, triphenyl phosphite, tris-2,4-dibutylphenyl phosphite and the like, and one or more of them can be used. Examples of the amine stabilizer include alkylated diphenylamine. Furthermore, as the low melting point phenol-based stabilizer, 2,6-ditertiarybutyl-4-methylhenol (melting point 69 ° C.), n-octadodecyl 3-3,5 ditertiary hydroxyphenyl propionate (melting point 49 to 54 ° C.) ) And the like, and can be used alone or in combination of two or more.

The blending ratio of the above-mentioned high melting point phenol-based stabilizer and other stabilizers is not particularly limited, but the phenol-based stabilizer: other stability in terms of the weight ratio in view of the stability effect required for rubber-reinforced styrene resins. Agent = 1: It is preferable that it is 0.0-3.0. In particular, a combination with a sulfur-based stabilizer, and more preferably phenol-based stabilizer: sulfur-based stabilizer = 1: 0.3 to 3.0.

Examples of emulsifiers that can be used in the present invention include anionic emulsifiers such as alkali metal salts of carboxylic acids such as rosin acid and higher fatty acids, alkali metal salts of alkyl sulfates, alkali metal salts of alkyl sulfonic acids, and the like. Nonionic emulsifiers such as oxyalkylene alkyl ethers can be mentioned, and one or more can be used. Of these, nonionic emulsifiers are particularly preferred.
Further, it is also possible to use a dispersant such as polyvinyl alcohol, polyalkylene oxide, sodium polyacrylate, and methylcellulose together with the emulsifier.
There is no particular limitation on the amount of the above-mentioned emulsifier (or combined use with a dispersant), and the minimum amount necessary for emulsifying the above-mentioned phenol-based stabilizer (or combined use with other stabilizers) is sufficient. is there. In general, the amount is 1 to 70 parts by weight per 100 parts by weight of a phenol-based stabilizer (or a total when used in combination with a dispersant).

  Also, the stabilizer emulsion is diluted with water to a concentration that is easy to handle. Generally, the solid content is 10 to 70% by weight.

  Furthermore, there is no restriction | limiting in particular as an installation which prepares an emulsified liquid, What is necessary is just an installation which can input, mix (stirring), and discharge | emit the phenol type stabilizer and emulsifier which are essential components by this invention, and water.

The stabilizer emulsion of the present invention comprises a phenol-based stabilizer having a melting point of 90 ° C. or higher, and if necessary, other stabilizers and an emulsifier, and has a weight average particle size of 0.1 to 1.0 microns, 70% or more. Particles are 1.0 microns or less. In the case of an emulsified liquid outside this range, the standing stability of the liquid itself is poor, and it separates over time. Moreover, even if it uses immediately after adjustment, it is inferior in miscibility with rubber-reinforced styrene resin latex, and an excessive addition is required.
Preferably, the weight average particle diameter is 0.2 to 0.8 microns, and 70% or more of the particles are 0.8 microns or less.

  As a method of preparing an emulsion having a particle size specified in the present invention, a high melting point phenol-based stabilizer is heated alone or together with an emulsifier and, if necessary, other stabilizers to a temperature higher than the melting point of the stabilizer. After liquefaction, the water is gradually added at a liquid temperature equal to or lower than the cloud point of the emulsifier to cause phase conversion from the W / O system to the O / W system. For example, by adjusting the stirring conditions at the time of phase change, for example, the power per unit volume (PV value) and the tip speed of the stirring blade, or by using a homogenizer (static mixer) having no stirring blade, By adjusting, the fine particle emulsion defined in the present invention can be obtained. Specifically, it can be carried out by the method described in Examples described later.

  The particle diameter of the stabilizer emulsion of the present invention can be confirmed with a normal particle measuring device. For example, it can be confirmed by a liquid phase dispersion sedimentation method using a centrifugal sedimentation type particle size distribution analyzer (SA-CP3L) manufactured by Shimadzu Corporation.

  The stabilizer emulsion of the present invention may further contain various compounds such as benzophenone, benzotriazole, benzoate, salicylate, and cyanoacrylate ultraviolet absorbers as necessary.

The stabilizer emulsion of the present invention is added to a latex of rubber-reinforced styrene resin produced by emulsion polymerization called ABS resin, AAS resin, AES resin, MBS resin or a slurry before salting out, for example. The rubber-reinforced styrene-based resin can be obtained by being uniformly dispersed in the latex (or slurry) and through subsequent steps after salting out. These resins can be suitably used for applications such as vehicles and electricity in the same manner as conventional resins.
The addition and blending amount of the stabilizer emulsion can be appropriately varied depending on the composition of the rubber-reinforced styrene resin, particularly the rubber content, salting-out / drying conditions, the target antioxidant level, and the like. Generally, the emulsion (solid content) is 0.01 to 1.0 part by weight, particularly preferably 0.05 to 0.5 part by weight per 100 parts by weight of the rubber-reinforced styrene resin latex (solid content). is there.

〔Example〕
The embodiment of the present invention will be described with the following stabilizer emulsion (solid content of about 30% by weight).
Phenol-based stabilizer: Wingstay manufactured by Good Year
L (product obtained by butylation of a reaction product of paracresol and dicyclopentadiene, melting point 115 ° C., average molecular weight 600 to 700).
Sulfur-based stabilizer: dilauryl 3,3 ′ thiopropionate.
Emulsifier: polyoxyethylene lauryl ether.
Phenol-based stabilizer: 1.0 part by weight Sulfur-based stabilizer: 1.0 part by weight Emulsifier: 0.3 part by weight Water: 5.4 parts by weight

[Example-1]
The total amount of emulsifier (liquid) is charged into a SUS kettle with a jacket, thermometer and stirrer with an internal volume of about 4 cubic meters (stirring power: 12.47 kW, P / V value: 10.39), and then the sulfur system is stabilized under stirring All the agent (powder) is charged. Steam is passed through the jacket, and after heating, when the temperature reaches 110 ° C., the whole amount of phenol-based stabilizer (powder) is added. After confirming the dissolution of the phenol-based stabilizer, water is gradually added, and W / O is changed to O / The phase was changed to W type. Thereafter, stirring was further continued for 60 minutes to obtain a stable emulsion. The weight average particle size and distribution of the resulting stabilizer emulsion are as follows.
Weight average particle size: 0.66 microns.
Particle distribution: 89.4% of particles less than 1.0 microns and 75.4% of particles less than 0.8 microns.
The resulting stabilizer emulsion was placed in a 500 ml graduated cylinder and allowed to stand at room temperature for 1 month. After standing, the presence or absence of separation of the liquid was confirmed, but no separation was observed.

[Example-2]]
To a SUS kettle (stirring power: 12.47 kW, P / V value: 10.39) with a jacket, thermometer and stirrer with an internal volume of about 4 cubic meters, a phenol-based stabilizer (powder) and a sulfur-based stabilizer ( The powder is charged in the total amount, and further 1/3 weight of water of the phenol stabilizer. Steam was passed through the jacket and heated. Stirring was started with a stirrer from 5 minutes from the start of heating to dissolve the phenol-based stabilizer. The temperature of the contents at this time was 91 ° C. Thereafter, the entire amount of the emulsifier (liquid) was added while stirring was continued. The temperature of the contents at this time was 70 ° C. Further, the remaining water was gradually added, the phase was changed from W / O to O / W type, and stirring was continued for 60 minutes to obtain a stable emulsion. The weight average particle size and distribution of the resulting stabilizer emulsion are as follows.
Weight average particle size: 0.70 micron Particle distribution: 86.2% of particles below 1.0 micron, 71.7% of particles below 0.8 micron.
The resulting stabilizer emulsion was placed in a 500 ml graduated cylinder and allowed to stand at room temperature for 1 month. After standing, the presence or absence of separation of the liquid was confirmed, but no separation was observed.

[Comparative Example-1]
Created in the same procedure as in Example 1, except that the stirring power was changed to 7.2 KW and the PV value was 6.0.
Weight average particle size: 0.76 micron Particle distribution: 62.6% of particles below 1.0 micron, 52.6% of particles below 0.8 micron.
When the obtained stabilizer emulsion was put into a 500 ml measuring cylinder and allowed to stand at room temperature, separation was observed from the third day after standing.

Various stabilizer emulsions prepared in Examples 1-2 and Comparative Example-1 were prepared from acrylonitrile-styrene-grafted polybutadiene latex (number average particle size: 0.4 micron, polybutadiene content: 50% by weight, solid content). 50 wt%) After adding 0.5 parts by weight per 100 parts by weight of solid content, ABS resin powder was obtained through salting out and drying steps with magnesium sulfate.
In Examples-1 and 2, no aggregates were observed in the salting out step, but in Comparative Example-1, the generation of aggregates was observed.
Moreover, in order to evaluate the antioxidant performance of these stabilizer emulsions, the oxidation heat generation start temperature was measured using the obtained ABS resin powder.
Example-2: 208 degreeC, Comparative example-1: 202 degreeC, It turned out that the performance of an emulsion with a bad dispersion state is inferior.
The oxidation heat generation start temperature is when DTA (model name: SSC5000) manufactured by Seiko Denshi Kogyo Co., Ltd. is used, and about 15 mg of ABS resin powder is heated at a rate of 10 ° C./min in an air atmosphere. Further, the temperature at which onset of heat generation due to oxidation is observed.

The phenol-based stabilizer emulsion of the present invention is excellent in standing stability, is excellent in addition efficiency, and exhibits a great antioxidant effect when used in a small amount. For this reason, it can utilize suitably for production of a rubber reinforced styrene resin as an antioxidant emulsion.

Claims (2)

It is a phenol stabilizer emulsion composed of a phenol stabilizer having a melting point of 90 ° C. or more, and a sulfur stabilizer and a nonionic emulsifier (however, the weight ratio of the phenol stabilizer to the sulfur stabilizer is , Phenol-based stabilizer: sulfur-based stabilizer = 1: 0.3 to 3.0)) , the weight average particle diameter of 0.2 to 0.8 microns, and 70% or more of the total particles A method for producing a rubber-reinforced styrene resin by adding a phenol-based stabilizer emulsion having a particle size of 0.8 microns or less to a rubber-reinforced styrene resin latex, uniformly dispersing in the latex, and passing through a salting-out step . The method for producing a rubber-reinforced styrene resin according to claim 1, wherein the phenol-based stabilizer is a product obtained by butylating a reaction product of paracresol and dicyclopentadiene.