KR100435046B1 - Thermoplastic resin composition with excellent molding and extrusion stability - Google Patents

Abstract

The present invention is a graft copolymer (I) formed by copolymerizing a vinyl cyanide compound (A) and a monomer (E) copolymerizable with an aromatic vinyl compound (S) or (A) (S) to a rubbery polymer (B). Composed of 80 to 50 parts by weight of copolymer (II) consisting of parts by weight and (A), (S) or (A), (S) and (E), the weight average molecular weight of the copolymer (II) 120,000-600,000 In the composition of (II), 0.01-3 parts by weight of a mixture composed of 1-99% by weight of polyfunctional mercaptan and 99-1% by weight of a vinylbenzene compound is copolymerized, and has a weight average molecular weight of 180,000 or more and inherent. A thermoplastic resin composition comprising component (II-1) having a viscosity of 0.6 or more, comprising a divalent metal salt, a divalent metal chloride, a divalent metal carbonate, and a divalent metal oxide based on 100 parts by weight of the resin composition (I + II). 0.001 to 10 parts by weight of at least one divalent compound selected from the group To provide a thermoplastic resin composition, characterized in that, the thermoplastic resin composition of the present invention is suitable for the production of various molded articles such as molded article with a large molded article or surface is excellent in vacuum formability and extrusion stability.

Description

Thermoplastic resin composition with excellent molding and extrusion stability

The present invention relates to a thermoplastic resin composition, and more particularly, in a composition of acrylonitrile-butadiene-styrene copolymer resin (hereinafter referred to as "ABS resin"), salts of divalent metals, chlorides of divalent metals, and di-porous metals. The present invention relates to a thermoplastic resin composition having improved moldability and extrusion stability, comprising at least one divalent compound selected from the group consisting of carbides in the genus, and oxides of divalent metals.

In general, ABS resin has excellent mechanical and thermal properties and beautiful appearance characteristics including physical properties such as processability of styrene, rigidity and chemical resistance of acrylonitrile, impact resistance of butadiene rubber, etc. It is widely used in the field of rigid molded products from daily necessities such as automobile parts and general office supplies to industrial goods.

Most of these molded products are manufactured by injection molding, but in the case of the size of the molded products being large or curved on the outside of the molded products, they are produced by vacuum molding or the like. Vacuum molding is a plastic sheet that obtains a product of a desired shape by extruded a sheet of resin and first prepares a sheet of sheet, then heat-softens the sheet in a vacuum molding machine and simultaneously performs vacuum or pressure and vacuum to adhere the softened sheet to a mold. It is a kind of molding method.

However, the conventional general ABS resin has a problem that a lot of thickness variation occurs during the vacuum molding, so that a very thin portion locally occurs, so that a lot of defects such as tearing occur at the portion. In order to solve this problem, the use of SAN copolymer having a large molecular weight and molecular weight distribution can reduce the thickness variation somewhat, but due to the deterioration of fluidity, the extruder load increases during compounding and sheet production, resulting in a decrease in productivity and color change. There is this.

Japanese Patent Publication No. 95-15039 discloses a technique for applying ABS resin having excellent paintability to blow molding of large parts by using a resin composition having a slightly larger molecular weight and molecular weight distribution than conventional ABS resin. However, simply increasing the molecular weight and the molecular weight distribution does not significantly improve the blow moldability of the ABS resin and thus has limitations in application.

On the other hand, Japanese Patent Publication No. 95-5820 discloses a technique using a copolymer copolymerized with an organic silane compound to improve blow property of ABS resin, but this method is manufactured by solution polymerization, which makes it difficult to mass-produce. There is a problem that the manufacturing cost increases.

In the case of sheet extruding the resin, the heat history and flow of the resin in the melting or plasticization process of the resin are locally different, and at a specific site, the resin is stagnant or vortices are generated to receive excessive heat history or heat for a long time. Receiving the history, the resin is changed to a different shape and a different composition black around the appearance and color. Some of these components may be formed into hard particles or solid lumps due to chemical or physical changes such as crosslinking, meshing, carbonization or flocculation, and may protrude in the shape of unmelted solids on an extruded sheet or molded product. The appearance of lumps on the surface of the product resembles a silver streak or a die line from the die, reducing appearance quality. In addition, the sheet-like products are protruded more easily through the vacuum forming process, the secondary processing process, causing fatal appearance defects. This aspect tends to be intensified when the size or size of the processing equipment is large.

Various studies have been conducted to improve the appearance defects occurring during the processing of the resins as described above. For example, Japanese Patent Laid-Open No. 6-16897 discloses an antioxidant compound such as a hindered phenolic stabilizer. A method of applying during processing has been proposed. According to this method, there is an effect of suppressing the oxidation reaction during processing to improve the color and physical properties of the resin, but there is a limit in that sufficient effects cannot be obtained under excessive thermal history such as stagnation or retention during processing.

On the other hand, Korean Patent Application No. 93-18486 proposes a method of improving the processability by using a low molecular weight polyethylene wax, ethylene bis steamide or a metal soap-based lubricant compound in an excessive amount during resin processing. In this method, however, the lubricant compound used reduces the friction between the metal and the resin during processing, which gives a processability improvement effect to some extent, but does not improve the crosslinking and carbonization of the resin under excessive thermal history which is stagnant for a long time. When the lubricant compound is used, the color stability of the resin decreases due to the increase of low molecular weight material which is easy to decompose, and the stretching property of the resin in the secondary processing process, such as vacuum forming, becomes worse.

An object of the present invention is to overcome the problems of the prior art described above, by mixing the non-linear SAN resin having a crosslinking point in the composition of the ABS resin to improve the vacuum formability by reducing the thickness deviation during vacuum molding without deterioration of fluidity To provide a thermoplastic resin composition having improved extrusion stability and formability by adding at least one or more divalent compounds selected from the group consisting of chlorides of divalent metals and oxides of divalent metals.

That is, the present invention is a graft copolymer (I) obtained by copolymerizing a vinyl cyanide compound (A) with an aromatic vinyl compound (S) or a monomer (E) copolymerizable with (A) or (S) in a rubbery polymer (B). It consists of 20-50 weight part and 80-50 weight part of copolymers (II) which consist of (A), (S) or (A), (S), and (E), and the weight average molecular weight of copolymer (II) It is 120,000-600,000, and the weight average molecular weight copolymerized 180,000 including 0.01-3 weight part of the mixture which consists of 1-99 weight% of polyfunctional mercaptans, and 99-1 weight% of vinylbenzene compounds in the composition of (II). A thermoplastic resin composition comprising component (II-1) having an intrinsic viscosity of 0.6 or more and having a divalent metal salt, a divalent metal chloride, a divalent metal carbonate, and a divalent metal oxide based on 100 parts by weight of the resin composition (I + II). 0.001 to 10 parts by weight of at least one divalent compound selected from the group consisting of It is to provide a thermoplastic resin composition comprising a.

Hereinafter, the present invention will be described in more detail.

First, the graft copolymer (I) is a graft copolymer that is emulsion-polymerized or bulk polymerized by a conventional method using 10 to 50 parts by weight of acrylonitrile and 90 to 50 parts by weight of styrene in the presence of 30 to 60 parts by weight of polybutadiene latex. For example, the acrylonitrile-styrene copolymer grafted to polybutadiene latex is 35 to 60 parts by weight, and the acrylonitrile content of the grafted acrylonitrile-styrene copolymer is suitably 15 to 45 parts by weight. Do. If the content of acrylonitrile in the grafted acrylonitrile-styrene copolymer is out of the above range, the compatibility with the ungrafted acrylonitrile-styrene copolymer (II) is insufficient, resulting in a decrease in mechanical properties. Not good because it can happen.

On the other hand, the vinyl cyanide compound-aromatic vinyl compound copolymer (II), which may be represented by an acrylonitrile-styrene copolymer, is prepared in a conventional manner using 10 to 50 parts by weight of a vinyl cyanide compound and 90 to 50 parts by weight of an aromatic vinyl compound. Polymerized copolymers generally have a linear structure. Copolymer (II-1) having a nonlinear structure is a copolymer polymerized including a mixture of a polyfunctional multicaptan and a vinylbenzene compound of 3 parts by weight or less with respect to 100 parts by weight of a vinyl cyanide compound and an aromatic vinyl compound. In particular, in order to improve the vacuum formation of ABS resin, the PS reduction weight average molecular weight of the copolymer (II-1) by GPC should be 180,000 or more, and the intrinsic viscosity of the copolymer in tetrahydrofuran solvent should be 0.6 or more. . When the molecular weight and the intrinsic viscosity are out of the above range, vacuum forming of ABS is not significantly improved regardless of the content of the copolymer, so that a uniform thickness distribution cannot be obtained.

The polyfunctional mercaptan that can be used in the present invention is a compound having three or more -SH groups, and there are trifunctional and tetrafunctional mulcaptans. The trifunctional mercaptans include trimetholpropane tri (3-mercaptopropionate), trimetholpropane tri (3-mercaptoacetate), trimetholpropane tri (4-mercaptobutanate) and trimetholamide. Tyrolpropane tri (5-mercaptopentanate), trimetholpropane tri (6-mercaptohexaonate) and the like can be used. Tetrafunctional mercaptans include pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (4-mercaptobutanate), and pentaerythrate. Lititol tetrakis (5-mercaptopentanate), pentaerythritol tetrakis (6-mercaptohexanate), and the like. In the present invention, the multifunctional mulcaptan may be used alone or in combination of two or more of the above compounds. Divinylbenzene etc. are mentioned as a vinylbenzene type compound which can be used by this invention. The above compounds are only for illustrating the present invention and do not have a limiting meaning.

U.S. Patent No. 4,918,159 discloses a method for producing a non-linear styrene resin using a multifunctional multicaptan, but when using the multifunctional multicaptan alone, the reactivity is slow and the dispersion system becomes very unstable as the polymerization proceeds. This may cause problems in the polymerization reaction control, such as a problem that the entire polymerization system is hardened.

On the other hand, Japanese Patent Application Laid-Open No. 59-149912 discloses that the copolymer made of a polyaromatic compound and a polyfunctional compound copolymerizable with a vinyl cyanide compound improves the fluidity and mechanical properties. In this case, there is a problem in that the reactivity is not easy to control the molecular structure of the resin.

The present invention can overcome the above problems, in the preparation of non-linear copolymer (II-1), the reactivity is controlled by using a highly functional divinylbenzene and a polyfunctional multicaptan that is slow and easy to gelation And by limiting the range of the weight average molecular weight and the intrinsic viscosity of the polymerized copolymer, it is characterized by improving the moldability of the ABS resin by greatly improving the stretching characteristics. The content of the mixture consisting of the polyfunctional mercaptan and the vinylbenzene compound used in the present invention is 0.01-3 parts by weight, more preferably 0.1-2 parts by weight, based on 100 parts by weight of the vinyl cyanide compound and the aromatic vinyl compound. The mixing ratio of the mercaptan and the vinylbenzene compound is a ratio of 99-1% by weight of the vinylbenzene compound to 1-99% by weight of the polyfunctional mercaptan. In the present invention, when the content of the mixture consisting of the multifunctional mercaptan and the vinylbenzene compound is less than 0.01 part by weight, the effect of improving the stretching property is not obvious, and when the content exceeds 3 parts by weight, the gelation reaction proceeds and the copolymer is usable. Not formed.

In the present invention, the weight average molecular weight of the copolymer (II) is preferably 120,000-600,000 when expressed in terms of styrene by gel permeation chromatography (GPC). If the weight average molecular weight is less than 120,000, it is difficult to obtain a molded article having a uniform thickness distribution due to the drawdown is severe, and when exceeding 600,000, there is a problem that the productivity is lowered and the color change occurs due to a lot of extrusion load during molding.

In the present invention, the rubbery polymer (B) is an acrylic such as a diene rubbery polymer such as polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, butyl acrylate-methyl methacrylate-methacrylate ester copolymer, etc. Saturated rubber polymers, such as rubber | gum and ethylene propylene copolymer rubber, etc. can be used. The content of the rubbery component in the resin is appropriately 10-30 parts by weight. If it is less than 10 parts by weight, the impact resistance is weak, and if it exceeds 30 parts by weight, problems such as insufficient rigidity of the molded article may occur.

Acrylonitrile or methacrylonitrile may be used as the vinyl cyanide compound constituting the copolymer (I) or (II) or (II-1) in the thermoplastic resin composition of the present invention. , Alphamethylstyrene, or a mixture of styrene and alphamethylstyrene may be applied, and methacrylic acid ester compounds such as methyl methacrylate or butyl acrylate, N phenylmaleimide, N cyclohexyl maleimide, maleic anhydride, and the like. This may be copolymerized.

The amount of the cyanide compound unit in the resin is appropriately 10-50 parts by weight of the resin component except for the rubbery polymer, if less than 10 parts by weight stress cracking occurs due to paint or thinner may cause problems in the appearance of the molded article. On the contrary, if it exceeds 50 parts by weight, problems such as discoloration of the resin may occur during reuse.

In another aspect, the present invention is characterized by solving the appearance problems and extrusion instability caused during extrusion by processing by adding a compound that can suppress the change of the resin, such as crosslinking or agglomeration at the time of resin processing in the resin manufacturing process. As the compound for improving the processing stability of the resin, at least one selected from the group consisting of salts of divalent metals, chlorides of divalent metals, carbonates of divalent metals and oxides of divalent metals can be used. These divalent compounds are inactive or weakly reactive through reactions and interactions with the active functioning part in the raw material resin or the additives used in polymerization of the raw material resin or in the preparation of the final resin to promote appearance problems. Or compound. Specific examples of such divalent compounds include zinc chloride, magnesium chloride, calcium chloride, magnesium carbonate, calcium carbonate, zinc oxide, magnesium oxide, calcium oxide, and the like.

The amount of the divalent metal compound used to improve processing stability in the present invention is 0.001-10 parts by weight based on 100 parts by weight of the raw material resin, and the addition rate of the divalent compound is less than 0.001 parts by weight to stabilize the processing of the resin. Insufficient, when the amount exceeds 10 parts by weight, the color of the compound itself is severely expressed in the resin, worsening the color of the resin and greatly lowering the physical properties of the resin, it is essential that the amount of the divalent compound in the present invention is within the above range. .

In the present invention, as the method for preparing the copolymers (I) and (II), known methods, that is, emulsion polymerization method, suspension polymerization method, solution polymerization method and the like can be used. Supplementary ingredients, such as stabilizers, lubricants, may be added.

The invention will be further elucidated by the following examples which are set forth for the purpose of illustrating the invention and are not intended to limit the scope of the invention.

EXAMPLE

Preparation Example 1 Preparation of Graft Copolymer (G-1)

45 parts by weight of polybutadiene latex (rubber average particle size 0.32㎛) and 200 parts by weight of deionized water were added to a polymerization reactor equipped with a stirring device, a reflux cooler, a thermometer, and a preparation device. 7 parts by weight of a 4% aqueous potassium perchlorate solution while stirring under a nitrogen stream. And 60 parts by weight of styrene and 40 parts by weight of acrylonitrile were added to the monomer mixture, and 0.1 parts by weight of t-dodecyl mercaptan was continuously added for 3 hours to polymerize at 70 ° C. The latex obtained here was dropped into 4% aqueous sulfuric acid solution heated to 90 ° C, washed, dehydrated and dried to obtain a graft copolymer (G-1). The graft ratio of the obtained copolymer was 50% and the weight average molecular weight of the ungrafted acrylonitrile styrene copolymer was 45,000.

Preparation Example 2 Preparation of Copolymer (II-1)

Styrene 71%, acrylonitrile 29%, ion exchanged water 150 parts, tricalcium phosphate 0.4 part, carboxylic acid anionic surfactant 0.03 part, polyoxyethylene alkyl ether phosphate ester, And 0.5 part of trimetholpropane tri (3-mercaptopropionate) trivalent as a polyfunctional mercaptan and 0.1 part of divinylbenzene were mixed with 0.5 part of 2,2'-azobisisobutylonitrile as an initiator. After the reactor was completely sealed, the mixture was sufficiently stirred to disperse, and then the internal temperature of the reactor was raised to proceed with polymerization at 75 ° C. for 6 hours. Subsequently, the inside of the reactor was cooled to room temperature to terminate the reaction, and then the obtained polymer was washed, dehydrated and dried to obtain a bead-like copolymer (II-1). The weight average molecular weight by GPC of the copolymer obtained at this time was 320,000.

Preparation Example 3 Preparation of Copolymer (II-1)

A copolymer (II-2) was prepared in the same manner as in Production Example 2, except that 1 part of trimetholpropane tri (3-mercaptopropionate) and 0.02 part of divinylbenzene were mixed and used.

Preparation Example 4 Copolymer (S-1) to Copolymer (S-3)

Copolymers (S-1) to (S-3) used in this example are as follows.

S-1: The weight average molecular weight is 260,000 to 350,000, and the content of acrylonitrile is

Acrylonitrile-styrene copolymer of 23 to 28% by weight.

S-2: The weight average molecular weight is 100,000 to 160,000, and the content of acrylonitrile is

Acrylonitrile-styrene copolymer of 36 to 42% by weight.

S-3: The weight average molecular weight is 100,000 to 120,000, and the content of acrylonitrile is

Acrylonitrile-styrene copolymer of 23 to 28% by weight.

Example 1

Graft copolymer (G-1) and acrylonitrile-styrene copolymer (II-1) and (S-3) were respectively mixed at a ratio of 40:30:30, and calcium chloride 1 was added to 100 parts by weight of the resin. Pellets were prepared using a twin screw extruder with a diameter of 40 mm by mixing parts by weight and a small amount of the heat stabilizer. The prepared pellets were made into 400mm × 400m × 2m compression specimens using a press, and then the lattice of 50 mm width and width was displayed on the compressed specimens, and then 300 mm (L) × 30 mm (W) × A vacuum molded article of 200 mm (H) was prepared, and the physical properties of the vacuum molded article were evaluated and shown in Table 1 below.

Example 2

Vacuum molded article was carried out in the same manner as in Example 1 except that the acrylonitrile-styrene copolymer (S-2) was changed to (S-3) and 0.5 parts by weight of magnesium oxide was mixed with respect to 100 parts by weight of ABS resin. To prepare and evaluate the overall physical properties are shown in Table 1 below.

Example 3

Except for changing the acrylonitrile-styrene copolymer (II-1) to (II-2) was carried out in the same manner as in Example 2 to prepare a vacuum molded article and to evaluate the overall physical properties shown in Table 1 below It was.

Comparative Example 1

Example except that graft copolymer (G-1) was mixed with acrylonitrile-styrene copolymer (II-1) and (S-3) in a ratio of 40:30:30 and calcium chloride was not used. In the same manner as in Example 1 to prepare a vacuum molded article and to evaluate the overall physical properties are shown in Table 1 below.

Comparative Example 2

The same procedure as in Example 1 was carried out except that the graft copolymer (G-1) was mixed with the acrylonitrile-styrene copolymer (S-1) and (S-3) in a ratio of 40:30:30. To prepare a vacuum molded article and to evaluate the overall physical properties are shown in Table 1 below.

Comparative Example 3

Example except that graft copolymer (G-1) was mixed with acrylonitrile-styrene copolymer (S-1) and (S-3) in a ratio of 40:30:30 and calcium chloride was not used. In the same manner as in Example 1 to prepare a vacuum molded article and to evaluate the overall physical properties are shown in Table 1 below.

[Property evaluation method]

(1) minimum thickness and standard deviation

The thickness of the intersection points of the lattice for the vacuum molded article was measured with a thickness meter with an accuracy of 1/100 mm. Large minimum thickness and small standard deviation can be said to be excellent in vacuum forming.

(2) increase and decrease of torque

The torque change was observed while kneading at 260 ° C. and 10 RPM for 1 hour using a kneading apparatus of Torque Rheometer manufactured by Haake, Germany. At this time, torque is increased by comparing the minimum torque (typically after 20 minutes of elapsed torque) observed after melting of the resin with the torque when 1 hour has elapsed. TQ) was obtained and the degree of processing stability was evaluated. If the torque is continuously decreasing, the torque is decreased by comparing the torque when 1 hour has passed with the torque when 20 minutes have passed since the kneading. TQ) was obtained. If the TQ exceeds 0, it means that the crosslinking proceeds, and thus the processing stability is poor. The larger the value, the lower the processing stability. And If the TQ is 0 or near 0, there is almost no change in the resin during processing, and thus the processing stability is good. TQ was computed by the following formula.

TQ (torque increase) = (torque of resin after 1 hour min.torque) or

TQ (torque reduction) = (torque after 1 hour-torque after 20 minutes)

As confirmed through the results of Table 1, the thermoplastic resin composition of the present invention is excellent in processing stability and vacuum forming, and thus can be effectively used for the production of various molded articles such as large molded articles or curved molded articles.

Claims (6)

Graft copolymer (I) 20 to which a rubbery polymer (B) is copolymerized with a vinyl cyanide compound (A), an aromatic vinyl compound (S), and optionally a monomer (E) copolymerizable with (A) and (S). 50 parts by weight; 10 to 40 parts by weight of copolymer (II), consisting of (A), (S) and optionally (E), having a weight average molecular weight in the range of 120,000-600,000; And (A), (S) and optionally (E) a mixture of 1-99% by weight of polyfunctional mercaptan and 99-1% by weight of a vinylbenzene compound. 0.01-3 parts by weight based on 100 parts by weight of the total amount of component (E) is copolymerized, and includes 10 to 40 parts by weight of copolymer (II-1) having a weight average molecular weight of 180,000 or more and an intrinsic viscosity of 0.6 or more. And divalent metal salts, divalent metal chlorides, divalent metal carbonates and divalent to 100 parts by weight of the thermoplastic resin composition having a sum of the content of the copolymer (II) and the content of the copolymer (II-1) of at least 50 parts by weight or more. A thermoplastic resin composition comprising 0.001 to 10 parts by weight of at least one divalent compound selected from the group consisting of valent metal oxides. The thermoplastic resin composition according to claim 1, wherein the divalent compound is selected from the group consisting of zinc chloride, magnesium chloride, calcium carbonate, zinc oxide, magnesium oxide and calcium chloride. The method of claim 1, wherein the multifunctional mercaptan is trimetholpropane tri (3-mercapto propionate), trimetholpropane (tri (3-mercaptoacetate), trimethyrolpropane tri (4-mercap) Tobutaneito), trimetholpropane tri (5-mercaptopentanate), trimetholpropane tri (6-mercaptohexaonate) pentaerythritol tetraki (2-mercaptoacetate), pentaerythritol tetra Keith (3-Mercaptopropionate), Pentaerythritol Tetrakis (4-Mercaptobutanate), Pentaerythritol Tetrakis (5-Mercaptopentanate), Pentaerythritol Tetrakis (6-Mercaptohexa) Nate), at least one member selected from the group consisting of a thermoplastic resin composition. The thermoplastic resin composition according to claim 1, wherein the vinylbenzene compound is divinylbenzene. The thermoplastic resin composition according to claim 1, wherein the vinyl tetrachloride compound (A) is an acrylonitrile compound, and the aromatic vinyl compound is a styrene compound. The thermoplastic resin composition according to claim 1, wherein the aromatic vinyl compound (S) is styrene or alphamethyl styrene.