PROCESS FOR THE PREPARATION OF LOW-GLOSS ABS RESINS

Abstract: The present invention relates to a process for the preparation of an ABS thermoplastic resin or resins comprising latex-blending ABS and butadiene-based rubber latices in the coagulation step, to form a polymeric gloss modifier containing PBD, SBR, or NBR latices in an amount of 25 weight percent or less of the total resin based on the solid content.

Description: PROCESS FOR THE PREPARATION OF LOW-GLOSS ABS RESINS BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a process for the preparation of an acrylonitπle- butadιene-styrene(ABS) thermoplastic resin or resins comprising latex-blending ABS and butadiene-based rubber latices in the coagulation step, to form a polvmeπc gloss modifier containing polybutadιene(PBD) rubber, styrene-butadiene rubber(SBR) oi acrylonitπle-butadiene rubber(NBR) latices in an amount of 25 weight percent or less of the total resin based on the solid content Description of the Related Art Vanous attempts have been made to develop a process to satisfactoπlv reduce the surface gloss of an article molded from a thermoplastic resin Some of the proposed solutions may include a method of improving processing techniques, and a method of incorporating inorganic fillers such as silica into the thermoplastic resin Howevei these methods tend to adversely affect the mechanical properties of the final products and further result in a high production cost In order to overcome the drawbacks mentioned abov e a method has been developed wherein control of the surface gloss is achieved through incorporating an organic additive such as a polymeric gloss modifier ha\ ing a lower thermal shrinkage than the thermoplastic base resin In this method, the particle size of the polymeric modifier distributed on the molded surface is considered as a ke factor for reducing the surface gloss In Japanese Pat No 58-93711 there is disclosed a process for preparing low- gloss ABS thermoplastic resins which comprises incorporating polystyrene into the ABS latex This method, however, is not effecti e in reducing the surface gloss of the resins and degrades the impact resistance of the products therefrom The surface gloss is lowered using another method preparing thermoplastic resins more specificallv. ABS thermoplastic resins using emulsion polymerization This piocesb compnses introducing carboxy c acids during emulsion polymerization and inducing a condensation reaction between the carboxyhc acids in the compounding step to achieve particle sizes that can effect a lowered surface gloss This method however, does not provide an appreciable gloss reduction due to the low yield of the condensation reaction, and further shows poor reproducibility. Korean Pat. Publication No. 93-6912 discloses processes for producing low-gloss ABS resins by using suspension polymerization or two-step of bulk and suspension polymerization. While the low-gloss ABS resins produced thereby meet the aforementioned requirements, the products molded therefrom suffer from other problems such as severe shrinkage, nonuniform gloss distribution and reduced hardness to an extent that varies greatly depending upon injection conditions, making the range of applications very limited. SUMMARY OF THE INVENTION An object of the present invention is to provide a novel process for the preparation of an ABS thermoplastic resin or resins comprising latex-blending in the coagulation step, to form a polymeric gloss modifier for ABS resins and products therefrom that overcomes many of the problems and disadvantages of the aforementioned prior art. Another object of the present invention is to provide a process for the preparation of an ABS thermoplastic resin or resins comprising mixing and coagulating ABS and butadiene-based rubber latices. to form an ABS thermoplastic resin or resins which can be used as a surface gloss modifier for thermoplastic resins. It is a further object of this invention to provide a process for the preparation of an ABS resin or resins as a gloss modifier which allows a simple production process and thus reduces the production cost compared to the prior art processes which adopt an emulsion or a 2-step bulk-suspension polymerization, without undermining the gloss characteristics and mechanical properties of the resulting polymer resins therefrom. DETAILED DESCRIPTION OF THE INVENTION The present invention provides, in embodiments, a process for the preparation of an ABS thermoplastic resin or resins comprising blending ABS and butadiene-based rubber latices in the coagulation step, to form a gloss modifier resin 01 resins containing a butadiene-based rubber latex in an amount of 25 percent or less b\ weight of the total resin based on the solid content In other embodiments of the present invention, there are provided a process foi the preparation of a low-gloss ABS thermoplastic resin or resins of which surface structure is reminiscent of clusters of grapes, wherein the clustered particles aie made oi the butadiene-based rubber compound In still other embodiments of the present invention, there are provided a process for the preparation of low-gloss ABS thermoplastic resins which does not undermine the mechanical properties of the resulting polymer resins therefrom, by forming strongl) bound clusters of butadiene-based rubber latex particles on the surfaces of relatively biggei ABS latex particles through partial miscibihty between the butadiene-based rubber latex particles and the rubbery component of the ABS latex particles during the aforementioned coagulation step The ABS thermoplastic resins and butadiene-based rubber compounds for use in the piesent invention may be prepared by any known polymerization processes One class of butadiene-based rubber compounds suitable for use in the present invention includes PBD(polybutadιene) rubber, SBR(styrene-butadιene rubber) and NBR (aciylonitπle-butadiene rubber) The preferred diameter of the butadiene-based rubbei latex particles is in the range of about 90 to about 400 nm. The present invention provides some specific advantages in embodiments as follows The invention provides a process for the preparation of a low-gloss ABS lesin oi resins which allows a simple production process and thus reduces the production cost compared to the prior art processes wherein a polymeric modifier is prepared in a separate process and incorporated into the ABS base resin as an additive, without undermining the gloss characteristics and mechanical properties of molded parts produced therefrom The polymer product of the present invention may be blended under normal processing conditions with other thermoplastic resins, for example, SAN (stv i ene- acrylonitrile copolymer) and poly carbonate(PC)/ABS blends, without compromising low gloss and mechanical properties for their expected uses such as auto inteπoi parts The surface gloss of the polymer resins of the current invention was e aluated as follows In a Henschell mixer. 30 to 80 parts by weight of PW-601 (a - J - styrene-acrylonitrile copolymer containing 69 parts by weight of -methv i stvrene commercially available from LG Chemical Ltd., Korea), 0.4 parts by weight of ethylene bisstearamide, 0.2 parts by weight of cyclic neopentane tetraalkyl bisbutyl phenyl phosphite. 0.2 parts by weight of butylidine bisbutyl methyl phenol, and 20 to 70 parts by weight of the polymer resin of the current invention were blended and dispersed. The resulting mixture was extruded into the form of pellets by using a single scre extruder at 220°C, and then the resulting pellets were injection-molded into a specimen preferrably plate-like in shape. The surface gloss of the samples was determined at a degree of 60° using a Glossometer (Toyo Seiki. Japan). The following Examples are being supplied to further define various species of the present invention, it being noted that these Examples are intended to illustrate and not limit the scope of the present invention. Parts and percentages are by weight unless otherwise indicated. Example I An NBR latex with an acrylonitrile content of 30 parts by weight (solid content 29 percent) and an ABS latex with a butadiene content of 40 parts by weight (solid content 39 percent) were used. The diameter of the NBR latex particles was about 150 nm. 120 parts by weight of aqueous anionic emulsifier, 0.7 parts by weight of sodium chloride. 0.3 parts by weight of -methyl styrene dimer, 0.05 parts by weight of sodium hydrosulfide. 40 parts by weight of acrylonitrile. and 0.2 parts by weight of potassium persulfate were charged into a clean reactor. The reactor as well as the reaction mixture was purged under an argon or nitrogen atmosphere. 60 parts by weight of butadiene were then added to the reactor and the resulting mixture was stirred and heated at a temperature of 65°C. At a conversion of 40 percent, 1.0 parts by weight of anionic emulsifier was added to the reactor over a time span of 30 minutes. When a conversion of 90 percent was reached, the reaction was terminated by adding diethyl hydroxv amine as an effective polymerization terminator, and the reaction mixture was cooled. Throughout the aforementioned reaction, the temperature within the reactor was maintained at 65°C. The pressure within the reactor was also maintained at under 6.0 kgf/cnr through a conversion of 50 percent. To 294 g of the NBR latex thus prepared were added 1965 g of ABS latex in a 5 L coagulation reactor at 50°C. which was followed by the addition of 3.5 parts by weight of potassium chloride as a coagulating agent. The resulting mixture was mixed together and aged until the temperature reached 80°C. In a Henschell mixer. 20 to 70 parts by weight of the polymer resin of the current invention, 30 to 80 parts by weight of PW-601 (a styrene-acrylonitrile copolymer containing 69 parts by weight of -methyl styrene commercially available from LG Chemical Ltd.. Korea), 0.4 parts by weight of ethylene bisstearamide. 0.2 parts by weight of cyclic neopentane tetraalkyl bisbutyl phenyl phosphite, and 0.2 parts by weight of butylidine bisbutyl methyl phenol were blended and dispersed. The resulting mixture was extruded into the pellet form by using a single screw extruder at 220°C. and then the resulting pellets were injection-molded into a specimen of a desired shape. Measurements were made of the surface gloss and impact strength on the samples thus prepared, and the results are shown in Table 1. Example II Example I was repeated with the exception that 1921 g of ABS latex and 352 g of NBR latex were used. The results are given in Table 1. Example III Example I was repeated with the exception that 1878 g of ABS latex and 41 1 g of NBR latex were used. The results are given in Table 1. Example IV Example I was repeated with the exception that 1834 g of ABS latex and 470 g of NBR latex were used. The results are given in Table 1. Example V Example I was repeated with the exception that 1790 g of ABS latex and 528 g of NBR latex were used. The results are given in Table 1. Example VI Example I was repeated with the exception that 1747 g of ABS latex and 587 g of NBR latex were used. The results are given in Table 1. Example VII A PBD latex (solid content 41 percent) with a particle diameter of 100 nm was prepared by a well-known method. Example I was repeated with the exception that 2919 g of ABS latex and 86 g of the aforementioned PBD latex were used. The results are given in Table 1. Example VIII Example VII was repeated with the exception that 2757 g of ABS latex and 138 g of PBD latex were used. The results are given in Table 1. Example IX Example VII was repeated with the exception that 2595 g of ABS latex and 186 g of PBD latex were used. The results are given in Table 1. Example X Example VII was repeated with the exception that 2435 g of ABS latex and 257 g of PBD latex were used. The results are given in Table 1. Example XI An SBR latex (solid content 33 percent) with a particle diameter of 100 nm and a styrene content of 20 parts by weight was prepared by a well-known method. Example I was repeated with the exception that 2235 g of ABS latex and 82 g of the aforementioned SBR latex were used. The results are given in Table 1. Example XII Example XI was repeated with the exception that 1978 g of ABS latex and 149 g of SBR latex were used. The results are given in Table 1. Example XIII Example XI was repeated with the exception that 1721 g of ABS latex and 201 g of SBR latex were used. The results are given in Table 1. Comparative Example I Example I was repeated with the exception that no NBR latex was used. The results are given in Table 1. Table 1 (Test Method) Impact Strength: ASTM D-256 6.4 mm notched

Claims: WHAT IS CLAIMED IS 1. A process foi the preparation of an acrylonιtrile-butadιene-styrene(ABS) resin thermoplastic resin or resins comprising mixing ABS and butadiene-based rubbei latices in the coagulation step to form a polymeric gloss modifier 2. A process in accordance with claim 1 wherein the butadiene-based rubber latex is in an amount of 25 weight percent or less of the total resin on the basis of the solid content 3. A process in accordance with claim 1 wherein the butadiene-based rubber contains 50 weight percent or less of acrylonitrile monomers. 4. A process in accordance with claim 1 wherein the butadiene-based rubber contains 50 weight percent or less of styrene monomers. 5. A process in accordance with claim 1 wherein the butadiene-based rubbei has a particle diameter ranging from 90 to 400 nm. 6. A thermoplastic resin prepared by blending a polymeric gloss modifier resin prepared in accordance with any one of the claims 1 to 5 with any thermoplastic resins 7. A thermoplastic resin in accordance with claim 6 wherein the thermoplastic resin is prepared by blending with a styrene-acrylonitrile copolymer

Inventors: YANG SE-WOO, YOO JIN-NYOUNG, YANG, SE-WOO, YOO, JIN-NYOUNG
Applicants: LG CHEMICAL LTD, YANG SE WOO, YOO JIN NYOUNG, LG CHEMICAL, LTD., YANG, SE-WOO, YOO, JIN-NYOUNG
Application year: 1998
Main classification: C08F279
IPC codes: C08F279, C08L9, C08L25, C08L55