KR101628580B1 - Method for preparing thermoplastic resin powder having anti-caking charateristics - Google Patents

Abstract

The present invention relates to a method for producing thermoplastic resin powder having excellent anti-caking properties and, more specifically, to a method for producing thermoplastic resin powder, in which powder caking occurring when the thermoplastic resin powder such as an acrylonitrile-butadiene-styrene (ABS) or acrylate-styrene-acrylonitrile (ASA) resin or the like is stored for a long time may be prevented. The method for producing thermoplastic resin powder comprises the following steps: (a) producing rubber modified graft copolymer powder by salting out a mixture of rubber modified graft copolymer latex, water, and an antioxidant through a salting-out agent; and (b) performing salting-out by adding emulsified SAN latex in a product obtained from step (a).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for manufacturing a thermoplastic resin powder,

The present invention relates to a method for producing a thermoplastic resin powder having excellent anti-caking properties, and more particularly, to a method for producing a thermoplastic resin powder having excellent anti-caking properties, and more particularly, to a method of producing acrylonitrile- -styrene-acrylonitrile (ASA) resin, which can prevent the caking phenomenon during the long-term storage of the thermoplastic resin powder.

In the case of acrylonitrile-butadiene-styrene (ABS) or acrylate-styrene-acrylonitrile (ASA) powder, when the content of acrylic rubber or butadiene rubber is high, When stored, transported or stored in the loaded state, solidification between the powders may occur due to the diffusion of the rubber, which is referred to as caking or blocking.

Such a solidification phenomenon may cause defective dispersion of the rubber in the matrix when the thermoplastic resin powder is extruded or injected to form a product, which may deteriorate the appearance quality such as mechanical properties, coloring property and gloss of the product.

On the other hand, conventionally, in the production of a thermoplastic resin, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, calcium of dicarboxylic acid, An anti-blocking agent such as cross-linked polymerized polystyrene particles and cross-linked acrylate particles is administered or a lubricant is administered to reduce the aggregation phenomenon between the rubber particles due to friction with the metal surface of the product molding apparatus, To prevent deterioration of the physical properties of the product.

For example, in Korean Patent No. 614787, issued to Stockhausen GmbH < RTI ID = 0.0 > GmbH, < / RTI > Compaq Kageka, granular materials of superabsorbent polymer particles passing less than about 60 weight percent through a US standard 50 mesh sheave are mixed to prevent caking of the powder / RTI >

However, the use of an anti-caking agent having a composition different from that of the powder may lower the physical properties of the product, in particular, the impact strength. Therefore, there is a continuing need for a method capable of improving the anti-caking property of the powder itself.

A problem to be solved by the present invention is to suppress the solidification phenomenon which may occur during the import and export of raw materials or long-term storage without deteriorating the physical properties of the final product, to improve the fluidity and storage stability of the powder itself, And to provide a method for producing a thermoplastic resin powder excellent in preventing properties.

In order to solve the above problems, the present invention provides a process for producing a thermoplastic resin powder, comprising the steps of: (a) salting out a rubber-modified graft copolymer latex, water and an antioxidant mixture with a salting agent to obtain a rubber-modified graft copolymer powder ; And (b) salting out the emulsion SAN latex to the product of step (a), wherein the emulsified SAN is added in an amount of 2 to 10 parts by weight based on 100 parts by weight of the rubber-modified graft copolymer do.

Though not to be limited theoretically, the surface of the primary salted rubber is adsorbed on the surface of a small amount of SAN by secondary salting, thereby preventing the rubber particles from being caked while preventing deterioration of the physical properties of the final product.

In the present invention, the step (a) and the step (b) may be continuously carried out in separate reactors.

(A) a rubber-modified graft copolymer latex, 0.1 to 2.0 parts by weight of an antioxidant, 1 to 10 parts by weight of a salting-out agent based on 100 parts by weight of a solid content of the rubber-modified graft copolymer latex, And 120 to 200 parts by weight of water to produce a rubber-modified graft copolymer powder; (b) transferring the salted (a) step product to a separate reactor; and adding a styrene-acrylonitrile (SAN) And salting out the thermoplastic resin powder.

In the step (a), an antioxidant and a salting agent are added to the rubber-modified graft copolymer latex to induce flocculation or salting-out reaction to produce a powdery rubber-modified graft copolymer mixed with water.

As the antioxidant, at least one selected from the group consisting of phenol, phosphorus, and sulfur ester may be used alone or in combination.

The amount of the antioxidant may be 0.1 to 2.0 parts by weight based on 100 parts by weight of the solid content of the rubber-modified graft copolymer latex. If the amount of the antioxidant is less than 0.1 parts by weight, the antioxidant may not provide a thermal stability effect. If the amount of the antioxidant is more than 2.0 parts by weight, economical efficiency may be deteriorated.

The salting agent may be at least one selected from the group consisting of citrate, edetate, glycolate, phosphate, hydrochloride, sulfate, acetate, tartrate, bromate, oxalate, lactate, carbonate and chloride salts Can be mixed.

The amount of the salting agent may be 1 to 10 parts by weight based on 100 parts by weight of the solid content of the rubber-modified graft copolymer latex. When the amount of the salting agent is less than 1 part by weight, aggregation or salting out reaction of the rubber-modified copolymer latex is less likely to occur. If the amount of the salting agent is more than 10 parts by weight, the rubber-modified graft copolymer latex and the salting agent react with each other The particle size distribution of the modified graft copolymer powder becomes uneven, and the mechanical properties and appearance quality of the final product may be deteriorated.

The rubber-modified graft copolymer latex may be one obtained by graft-polymerizing at least one of an aromatic vinyl compound and a vinyl cyan compound onto an acrylic or conjugated diene rubber latex.

In the graft copolymer, the rubber may be 50% by weight, preferably 60% by weight, for example, 60 to 80% by weight.

The aromatic vinyl compound may be at least one member selected from the group consisting of styrene, alphamethylstyrene, alphaethylstyrene, paramethylstyrene, and vinyltoluene, preferably styrene, but is not limited thereto.

The vinyl cyan compound may be at least one member selected from the group consisting of acrylonitrile, methacrylonitrile, and ethacrylonitrile, and may preferably be acrylonitrile, but is not limited thereto.

The rubber-modified graft copolymer latex may be an acrylonitrile-butadiene-styrene (ABS) latex or an acrylate-styrene-acrylonitrile (ASA) latex.

Meanwhile, in the step (b), the powder produced in the step (a) is transferred to the step (b), the emulsified SAN (styrene-acrylonitrile) is collectively administered, and salting out with the salting agent remaining in water, The modified graft copolymer powder is aged and dehydrated and dried to recover the thermoplastic resin powder.

The emulsified SAN is understood to mean an emulsion-polymerized styrene-acrylonitrile copolymer latex. Preferably 60 to 80% by weight of styrene and 20 to 40% by weight of acrylonitrile.

The amount of the emulsified SAN (styrene-acrylonitrile) may be 2 to 10 parts by weight based on 100 parts by weight of the solid content of the rubber-modified graft copolymer latex.

If the dose of the emulsified SAN is less than 2 parts by weight, the caking preventing property expected in the thermoplastic resin powder can not be provided. If the amount is more than 10 parts by weight, the impact strength of the produced thermoplastic resin powder may be lowered.

The emulsified SAN may have an average particle diameter of 1,000 ANGSTROM to 3,000 ANGSTROM, preferably 1,500 to 2,500 ANGSTROM.

If the average particle diameter of the emulsified SAN is less than 1,000 ANGSTROM, the smaller the particle size, the more the unit surface area increases and diffusion to the thermoplastic resin powder may actively occur. However, the emulsifier SAN content If the thickness is more than 3,000 ANGSTROM, the emulsification stability of the emulsified SAN may be lowered, and diffusion and coating of the emulsified SAN into the thermoplastic resin powder may be inhibited.

In the above-mentioned processes (a) and (b), the temperature of the reactor is Ta and Tb, respectively, and Ta?

In the step (a), an antioxidant and a salting agent are added to the rubber-modified graft copolymer latex to produce a powdery rubber-modified graft copolymer, and the rubber-modified graft copolymer latex It is preferable to maintain the temperature of the reactor at Ta since a sufficient level of heat is required to initiate coagulation or salting out reaction of the coalesced latex.

In the step (b), the powder produced in the step (a) is transferred to the step (b), and the emulsified SAN is administered in a batch to agglomerate the rubber-modified graft copolymer powder, followed by dehydration and drying to obtain a thermoplastic resin In order to recover the powder, it is preferable to increase the temperature of the reactor to Ta or more, since it is necessary to further heat a sufficient level of heat so that the reactant in the step (a) does not remain.

On the other hand, the Ta may be 75 to 85 ° C, and the Tb may be 85 to 95 ° C.

In the step (a), the temperature (Ta) of the reactor may be maintained at 75 to 85 ° C through a heat exchanger. If the temperature Ta is less than 75 ° C, the reaction time may be long due to a low reaction temperature. If the temperature Ta is higher than 85 ° C, it may be difficult to control the process due to excessive reaction heat in the subsequent step.

Also, in the step (b), the temperature (Tb) of the reactor may be raised and maintained at 85 to 95 ° C through a heat exchanger. If the temperature Tb is less than 85 ° C, it is difficult to react the residual reactant in the step (a). If the temperature Tb is higher than 95 ° C, it may be difficult to control the process due to excessive reaction heat in the step of recovering the powder.

According to one embodiment of the present invention, by applying styrene-acrylonitrile (SAN) to the thermoplastic resin powder as a raw material, uniform coating induction on the surface of thermoplastic resin powder and bridge phenomenon between thermoplastic resin powders The caking prevention property of the thermoplastic resin powder produced can be improved.

1 is a schematic view illustrating a method for producing a thermoplastic resin powder according to an embodiment of the present invention.
2 is a diagram illustrating a process for producing a thermoplastic resin powder according to an embodiment of the present invention.
FIG. 3 is a schematic view illustrating a caking test method of a thermoplastic resin powder produced according to a method for producing a thermoplastic resin powder according to an embodiment of the present invention.
FIG. 4 is a schematic view showing a caking test result of the thermoplastic resin powder produced according to the method for producing a thermoplastic resin powder according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" . Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The process according to the present invention consists of a process as shown in Figs. 1 and 2.

Example 1

ASA latex (Kumho XC140), which is an intermediate product before the production of the thermoplastic resin powder, was used. The ASA latex is a latex prepared by graft-polymerizing 40 wt% of a monomer mixture of styrene and acrylonitrile in a weight ratio of 7: 3 in 60 wt% of acrylic rubber.

The emulsion SAN is a latex having a weight average molecular weight of 80,000 and an average particle size of 2,000 Å, which is composed of styrene and acrylonitrile in a weight ratio of 7: 3.

The powder was agglomerated at an agglomeration temperature of 82 to 85 ° C in the step (a) using 0.6 parts by weight of antioxidant, 150 parts by weight of pure water and 4 parts by weight of salting agent based on 100 parts by weight of the solid content of the ASA latex. After transferring the salting out product produced in the step (a) to the step (b), the emulsified SAN of 2 parts by weight (based on the solid basis) based on the solid content of ASA latex was collectively administered and allowed to stand at 95 ° C for 5 minutes, And dried to obtain a thermoplastic resin powder.

Example  2

6 parts by weight of the emulsified SAN were batch-administered, and the ingredients and the manufacturing process were the same as those of Example 1 in the production of the thermoplastic resin powder.

Example  3

In addition to 10 parts by weight of the emulsified SAN as a batch, the ingredients and the manufacturing process used in the production of the thermoplastic resin powder were the same as in Example 2.

Comparative Example  One

ASA latex (Kumho XC140), which is an intermediate product before the production of the thermoplastic resin powder, was used. The ASA latex is a form in which 60% by weight of acrylic rubber is stained with 7: 3 grafted styrene and acrylonitrile, or the coated resin is dispersed in water.

(A) an ASA latex and an emulsified SAN were treated by administering 0.6 parts by weight of an antioxidant, 150 parts by weight of pure water, 4 parts by weight of a salting agent and 2 parts by weight of an emulsified SAN having an average particle diameter of 2,000 Å, based on 100 parts by weight of the solid content of the ASA latex. The powder was agglomerated simultaneously at the agglomeration temperature of 82 to 85 ° C.

After the powder produced in the step (a) was transferred to the step (b), (b) the resin was allowed to stand at 95 ° C for 5 minutes, followed by washing with water and dehydration to obtain a thermoplastic resin powder.

Comparative Example  2

In addition to 6 parts by weight of emulsified SAN as a batch, the ingredients and process for preparing the thermoplastic resin powder were the same as in Comparative Example 1.

Comparative Example  3

In addition to batchwise administration of 10 parts by weight of the emulsified SAN, the ingredients and manufacturing process used in the preparation of the thermoplastic resin powder were the same as in Comparative Example 1.

Comparative Example  4

0.6 parts by weight of antioxidant, 150 parts by weight of pure water and 4 parts by weight of salting agent were administered based on 100 parts by weight of solid component of ASA latex and the powder was agglomerated at 82-85 DEG C in step (a) without the introduction of emulsification SAN. The powder produced in the step (a) was transferred to the step (b) in the step (b), and the powder was allowed to stand at 95 ° C for 5 minutes, followed by washing with water and dehydration to obtain a thermoplastic resin powder.

Comparative Example  5

In addition to 15 parts by weight of emulsified SAN as a batch, the ingredients and manufacturing process used for preparing the thermoplastic resin powder were the same as in Example 1.

Experimental Example  1: Thermoplastic resin powder Cohesiveness  exam

FIG. 3 is a schematic view showing a caking test method of the thermoplastic resin powder according to Experimental Example 1. FIG.

Specifically, in Example 1-3 and Comparative Example 1 The thermoplastic resin powder to 5 In the thermoplastic resin powder 30g prepared according to the method for producing the mold of the cylinder-shaped having an inner diameter of 45mm, height 100mm, and 1kg / cm ² And stored at 40 ° C and 85% RH (relative humidity) for 3 hours under pressure. Then, the prepared powder block was placed on a sieve having a mesh interval of 4 mm, and the powder block was vibrated at 100 Hz for 100 seconds. After 5 minutes, the weight of the powder remaining on the sieve was measured and the amount of powder remaining relative to the powder block charged was calculated.

In this case, a high residual ratio means that the powder block can not be broken down to a fine powder enough to pass through the sieve, which means that the caking preventing property of the thermoplastic resin powder is poor.

Experimental Example  2: Physical property test of the final product

The purpose of this study was to investigate the effect of emulsified SAN on the physical properties of the final product when preparing the thermoplastic resin powder. To 100 parts by weight of a resin composition consisting of 44% by weight of each thermoplastic resin powder prepared in Examples 4 to 6 and Comparative Examples 1 to 5 and 56% by weight of a general SAN, 0.2 parts by weight of an antioxidant (SON 147BF, manufactured by Songwon Industry) And 0.7 part by weight of a lubricant (Pioneer Chemical, SUNLUBE) were mixed, and a specimen was prepared using a twin extruder and an extruder at 230 캜. The physical property evaluation items and evaluation methods for the specimens are as follows.

- Impact strength: measured according to ASTM D256 at a thickness of 3.2 mm.

- Flow Index: measured according to ASTM D1238.

- Tensile strength: measured according to ASTM D638.

- Thermal Stability: The resin was held for 10 minutes inside an injection machine screw set at 240 ° C, and then the difference in color between the molded specimen and the specimen not retained was evaluated. The evaluation index indicates the amount of change in? E.

-? E =

The dosage of each component to be administered in accordance with the method for producing the thermoplastic resin powder of each of Examples 1 to 6 and Comparative Examples 1 and 2 and the coagulation property of the thermoplastic resin powder prepared through Experimental Examples 1 and 2 and the physical properties The test results are shown in Table 1 and FIG.

In Experimental Example 1, if the residual rate of the powder after confirming the temperature of the sieve without controlling the temperature, humidity, and pressure is less than 0.5%, it is impossible to confirm the deviation of the caking prevention characteristic. This is because, in the case of a simple process in which hard styrene and acrylonitrile are first grafted or coated on a rubber latex due to the characteristics of an ASA or an ABS product to recover the powder in the latex state, solidification between powders does not occur.

Accordingly, it is possible to control the process parameters such as temperature, pressure, and humidity to a specific value or range to cause solidification between powders. As a result, the caking prevention characteristics of the thermoplastic resin powder according to the above Examples and Comparative Examples can be compared.

In the above evaluation method, the residual ratio may vary according to the process variables such as temperature, humidity, and pressure. However, since the residual ratio is relatively wide in the condition of Experimental Example 1, have.

As can be seen from the test results of Examples 1 to 3 and Comparative Examples 1 to 5, as the content of the emulsifying SAN used as the caking inhibitor increases, the residual ratio decreases. However, when the emulsifying SAN dosage is less than 2 parts by weight, It was confirmed that the solidification degree of the thermoplastic resin powder was increased with the increase of the ratio, and the residual ratio was decreased when the amount of the thermoplastic resin powder was 10 parts by weight or more. However, it was confirmed that the impact strength was decreased as the content of the acrylic rubber, .

As a result of the test results of Comparative Examples 1 to 3, in the step (a), it is impossible to induce a uniform coating on the surface of the thermoplastic resin powder in the form of the thermoplastic resin powder in which the ASA latex and the oil- bridge phenomenon (the start of solidification through adsorption between powders) can not be efficiently removed, there is not a great reduction in the residual ratio, which is an index of the caking prevention property of the thermoplastic resin powder produced.

On the other hand, according to the test results of Examples 1 to 3, the thermoplastic resin powder of the ASA latex coagulated in the step (a) is agglomerated with the emulsification SAN in the step (b) to diffuse and uniformly coat the thermoplastic resin powder on the surface And the decrease rate of the residual rate was large.

According to the test result according to Experimental Example 5, when the emulsified SAN was administered during the production of the thermoplastic resin powder, the caking-preventing property was improved at a low residual ratio without deteriorating the mechanical properties including impact strength and thermal stability. That is, it was confirmed that the physical properties of the final product can be maintained at a certain level while improving the storage stability of the thermoplastic resin powder.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (7)

(a) salting the rubber-modified graft copolymer latex, water and antioxidant mixture with a salting agent to produce a rubber-modified graft copolymer powder wherein the rubber-modified graft copolymer latex is an acrylate-styrene-acrylonitrile Latex; And
(b) introducing an emulsified SAN latex into the product of step (a) and salting out,
Wherein the emulsified SAN is added in an amount of 2 to 10 parts by weight based on 100 parts by weight of the rubber-modified graft copolymer. delete The method according to claim 1, wherein the emulsion SAN (styrene-acrylonitrile) copolymer latex has an average particle diameter of 1,000 ANGSTROM to 3,000 ANGSTROM. The method according to claim 1, wherein the content of the rubber in the graft copolymer is 60 to 80% by weight. The method according to claim 1, wherein the steps (a) and (b) occur in separate reactors, wherein the temperature of the step a reactor and the temperature of the step b reactor are Ta and Tb, respectively, Lt; / RTI > 6. The method according to claim 5, wherein the Ta is 75 to 85 deg. C and the Tb is 85 to 95 deg. The rubber-modified graft copolymer latex according to claim 1, wherein 0.1 to 2.0 parts by weight of an antioxidant, 1 to 10 parts by weight of a salting agent and 120 to 200 parts by weight of water are added to 100 parts by weight of a solid content of the rubber- To produce a copolymer powder.

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