KR19990054109A - Styrene-based resin composition excellent in drawing property and moldability - Google Patents

Abstract

The styrene-based thermoplastic resin composition of the present invention is a graft copolymer (I) obtained by copolymerizing a vinyl cyanide compound (A) and an aromatic vinyl compound (S) in a rubbery polymer (B), and the vinyl cyanide compound (A) and an aromatic vinyl. Copolymer (II) composed of compound (S), and vinyl cyanide compound (A), aromatic vinyl compound (S), and vinyl-based mercaptan compound (M) copolymerize to copolymer (III) having a nonlinear structure. Is done. The copolymer (I) or (II) may further include another monomer (E) copolymerizable with the vinyl cyanide compound (A) and the aromatic vinyl compound (S) to form a copolymer. As for the content rate of the said copolymer (I), (II), and (III), the range of 25-40: 25-40: 25-50 is preferable. The weight average molecular weight of the copolymer (II) is in the range of 120,000 to 600,000, and the copolymer (III) contains 0.0001 to 5 parts by weight of the vinyl mercaptan compound (M), and has a weight average molecular weight of 180,000 or more and 0.6 or more. It is preferable to have intrinsic viscosity.

Description

Styrene-based resin composition excellent in drawing property and moldability

Field of invention

The present invention relates to a styrene thermoplastic resin composition. More specifically, the present invention relates to a styrene-based thermoplastic resin composition excellent in stretchability and excellent in moldability suitable for vacuum molding or blow molding by reducing the thickness variation of the molded article.

Background of the Invention

Styrene-based thermoplastic resin compositions are used as resin raw materials for vacuum molding and blow molding.

Vacuum molding is a plastic sheet that obtains a product of a desired shape by extruding a sheet and manufacturing a sheet sheet first, and then softening the sheet in a vacuum molding machine and simultaneously performing vacuum or pressure and vacuum to adhere the softened sheet to a mold. It is a kind of molding method. This method is widely used to make the inner sheet of the refrigerator, and generally uses acrylonitrile-butadiene-styrene copolymer resin (ABS resin). This is because ABS resin not only has good mechanical properties and processability but also has excellent appearance and gloss. ABS resin here means the resin composition which mixed the acrylonitrile-styrene copolymer (SAN) which is 10-50 weight part in presence of polybutadiene rubber. However, the conventional general ABS resin has a problem that a lot of defects occur because a lot of thickness deviation occurs when forming a vacuum very locally a very thin portion. In order to solve this problem, when using SAN copolymer having high molecular weight and molecular weight distribution when compounding, thickness variation can be slightly reduced, but productivity is lowered and color is reduced because compounding and sheet production are overloaded due to fluidity deterioration due to high molecular weight. There is a disadvantage that changes occur.

On the other hand, blow molding is a molding technology for making hollow products such as plastic bottles, and its range is gradually expanded from forming of small containers to manufacturing of large structural materials. This method is inexpensive compared to injection molding, and it is possible to have a variety of designs since the structure of the molded product can be curved, and in particular, the use of the mold has been gradually expanded due to the advantage of having low residual stress.

In the case of manufacturing large molded articles, polyolefins such as low density polyethylene have excellent moldability, but when coating is required, there is a problem in applying structural materials due to low adhesion strength of the coating film, and in the case of modified polyphenylene ether, coating film adhesion, heat resistance, etc. It is excellent, but the chemical resistance is not good, so stress cracks are caused by thinner, etc.

ABS resin, an acrylonitrile-butadiene-styrene copolymer, has been widely used in injection molding and vacuum molding because of its mechanical properties, ease of molding, and beautiful appearance, but it has a heavy drawdown and a thick molding of the molded article. Often difficult to use.

Japanese Patent Publication JP95015039 discloses a technique for applying ABS resin having excellent paintability to blow molding of large parts. However, although the above problems are somewhat solved by using a resin composition having a specific molecular weight and a molecular weight distribution, a special technique is used except that ABS resins having a large molecular weight and molecular weight distribution are used as compared to the general ABS resins used for injection molding. In fact, simply increasing the molecular weight and molecular weight distribution does not significantly improve the blow moldability of ABS.

Japanese Patent Publication JP95005820 discloses a technique using a copolymer copolymerized with an organosilane compound in order to improve blow property, but this method has a problem of mass production and solution cost due to solution polymerization. .

In order to solve the above problems, the present inventors use a non-linear vinyl cyanide compound-aromatic vinyl compound copolymer, which has almost no fluidity deterioration, reduces the thickness deviation during vacuum molding, and improves the vacuum formation. It has developed a resin composition suitable for blow molding of large parts, which have high strength and low drawdown, and have low thickness and thickness of blow molded products.

An object of the present invention is to provide a styrene-based thermoplastic resin composition which hardly causes a decrease in fluidity during molding.

Another object of the present invention is to provide a styrene-based thermoplastic resin composition with improved stretching characteristics.

Another object of the present invention is to provide a styrene-based thermoplastic resin composition suitable for vacuum molding by reducing the thickness deviation of the molded article during vacuum molding.

Still another object of the present invention is to provide a styrene resin composition suitable for blow molding of a large part having a small thickness thickness of the molded article during blow molding.

The above and other objects of the present invention can be achieved by the present invention described below.

Summary of the Invention

The styrene-based thermoplastic resin composition of the present invention is a graft copolymer (I) obtained by copolymerizing a vinyl cyanide compound (A) and an aromatic vinyl compound (S) in a rubbery polymer (B), and the vinyl cyanide compound (A) and an aromatic vinyl. Copolymer (II) composed of compound (S), and vinyl cyanide compound (A), aromatic vinyl compound (S), and vinyl-based mercaptan compound (M) copolymerize to copolymer (III) having a nonlinear structure. Is done.

The copolymer (I) or (II) may further include another monomer (E) copolymerizable with the vinyl cyanide compound (A) and the aromatic vinyl compound (S) to form a copolymer.

As for the content rate of the said copolymer (I), (II), and (III), the range of 25-40: 25-40: 25-50 is preferable. The weight average molecular weight of the copolymer (II) is in the range of 120,000 to 600,000, and the copolymer (III) contains 0.0001 to 5 parts by weight of the vinyl mercaptan compound (M), and has a weight average molecular weight of 180,000 or more and 0.6 or more. It is preferable to have intrinsic viscosity.

Detailed Description of the Invention

The styrene-based thermoplastic resin composition of the present invention is a graft copolymer (I) obtained by copolymerizing a vinyl cyanide compound (A) and an aromatic vinyl compound (S) in a rubbery polymer (B), and the vinyl cyanide compound (A) and an aromatic vinyl. Copolymer (II) composed of compound (S), and vinyl cyanide compound (A), aromatic vinyl compound (S), and vinyl-based mercaptan compound (M) copolymerize to copolymer (III) having a nonlinear structure. Is done.

First, the graft copolymer (I) is emulsified and 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 having a particle diameter of 0.1 to 0.6 m. As the graft copolymer, 35 to 60 parts by weight of the acrylonitrile-styrene copolymer grafted to polybutadiene latex, and the content of acrylonitrile in the grafted acrylonitrile-styrene copolymer is 15 to 45 It is appropriate by weight. 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.

The copolymer (I) may further include another monomer (E) copolymerizable with the vinyl cyanide compound (A) and the aromatic vinyl compound (S) to form a copolymer.

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.

The copolymer (III) may further include another monomer (E) copolymerizable with the vinyl cyanide compound (A) and the aromatic vinyl compound (S) to form a copolymer.

The copolymer (III) having the nonlinear structure is a copolymer polymerized containing 5 parts by weight or less of a vinyl mercaptan compound with respect to 100 parts by weight of a vinyl cyanide compound and an aromatic vinyl compound. In particular, in order to improve vacuum forming of the ABS resin, the PS reduction weight average molecular weight of the copolymer (III) by GPC is 180,000 or more, and the intrinsic viscosity of the copolymer in a tetrahydrofuran solvent is 0.6 or more. . When the molecular weight and intrinsic viscosity are out of the above ranges, regardless of the copolymer content, vacuum forming of ABS resin does not improve clearly, so that uniform thickness distribution cannot be obtained. Blow forming also does not improve clearly. It is not suitable for molding.

US Pat. No. 4,918,159 proposes a method for producing a non-linear styrene resin using a multifunctional mercaptan. However, when the polyfunctional mercaptan alone is used, the dispersion system becomes very unstable as the polymerization progresses. There is a problem in controlling the polymerization reaction such that the whole polymerization system is hardened. Japanese Patent Application Laid-Open No. 59-149912 discloses that copolymers made of a polyaromatic compound and a polyfunctional compound copolymerizable with a vinyl cyanide compound have an effect of improving fluidity and mechanical properties, but are divinyl exemplified as a polyfunctional compound. In the case of benzene, it is not easy to control the molecular structure of the resin due to its high reactivity, and more specifically, the weight average molecular weight is 180,000 or more unless the range of PS reduction weight average molecular weight and intrinsic viscosity by GPC is not limited. Unless the intrinsic viscosity is 0.6 or more, the effect of improving moldability cannot be expected.

On the other hand, a chain transfer agent is used to obtain a desired molecular weight and molecular weight distribution in the production of styrene-based resin, and a mulcaptan-based compound is used for this purpose. However, when the mercaptan-based chain transfer agent is used, unreacted mercaptan compound remains in the resin after the reaction, and thus even a small amount of mercaptan causes odor to adversely affect the product. Therefore, many researchers are researching for replacement or reduction thereof, and a number of patents are pending.

The present inventors have studied to achieve the above object, as a result, has a vinyl group copolymerizable with a vinyl monomer during the polymerization of styrene-based resin, and at the same time a vinyl-based containing mercaptan group in the molecule to act as a chain transfer agent The use of the mercaptan compound prevents the gelation during the reaction that can occur when the polyfunctional compound is used, reduces the odor caused by the remaining mercaptan, and controls the amount of the vinyl-based mercaptan compound to control the nonlinear structure. It has been found that it is possible and therefore can change the moldability and processability of the resin.

In the present invention, in the preparation of the copolymer (III), a vinyl-based mercaptan compound is used to produce a nonlinear structure, and the stretching property is greatly improved 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. The content of the vinyl mercaptan compound used in the present invention is 0.0001 to 5 parts by weight, more preferably 0.01 to 3 parts by weight based on 100 parts by weight of the vinyl cyanide compound and the aromatic vinyl compound.

Vinyl-based mercaptan compound that can be used as a non-linear center in the present invention has the following structure.

R ¹ is hydrogen or a methyl group, R is a phenyl group, halophenyl group, alkyl group, alkylphenyl group, or alkylhalophenyl group, which may include an ester group and a sulfonic acid group, and preferably an alkylphenyl group. Halophenyl is substituted with one or two halogen compounds in phenyl group, alkylphenyl group is substituted with one or two alkyl groups in phenyl, and alkylhalophenyl group is substituted with alkyl group containing halogen compound or halogen and alkyl group together Say that it has been. In addition, the vinyl-based mercaptan may be used alone or in combination of several vinyl-based mercaptans.

When the content of the compound is 0.01 parts by weight or less, the effect of improving the stretching property is not obvious, and when 3 parts by weight or more, gelation proceeds and cannot be used. In addition, when the PS-reduced weight average molecular weight by GPC is 180,000 or less or the intrinsic viscosity in tetrahydrofuran solvent is 0.6 or less, the effect of improving the stretching property is not obvious, and the upper limit of the allowable weight average molecular weight and intrinsic viscosity is for use. The range is not limited unless gelation proceeds sufficiently as it may be applied differently depending on the situation.

As for the weight average molecular weight of copolymer (II), 120,000-600,000 are suitable when it shows in styrene conversion value by gel permeation chromatography (GPC). When 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, and when the weight average molecular weight is more than 600,000, the extrusion load is increased during molding, resulting in a decrease in productivity and a change in color.

In the present invention, the rubber polymer used to prepare the graft copolymer (I) is a diene rubber polymer such as polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, butyl acrylate-methylmetha Acrylic rubber, such as a methacrylate-methacrylic acid ester copolymer, saturated rubbery polymers, such as ethylene-propylene copolymer rubber, etc. can be used. The content of the rubbery component in the resin is appropriately 10 to 30 parts by weight. If it is less than 10 parts by weight, the impact resistance is weak.

The vinyl cyanide compound constituting the copolymer (I), (II) or (III) in the thermoplastic resin composition of the present invention is agrylonitrile or methacrylonitrile, and an aromatic compound is styrene, alphamethylstyrene or Mixtures of styrene and alphamethylstyrene may be applied, and these may be copolymerized with methacrylic acid ester compounds such as methyl methacrylate or butyl acrylate, N-phenylmaleimide, N-cyclohexylmaleimide, maleic anhydride, and the like. have. The amount of the cyanide compound unit in the resin is appropriately 10 to 50 parts by weight of the resin components excluding the rubbery polymer. If the amount is less than 10 parts by weight, stress cracking may occur due to paint or thinner and may cause problems in the appearance of the molded article. If more than the weight part may cause problems such as discoloration of the resin when reuse of the bar portion.

As a method for preparing the copolymers (I) and (II), known methods, that is, emulsion polymerization method, suspension polymerization method, solution polymerization method, and the like, are applied. For the present resin composition, auxiliary components such as heat stabilizers and lubricants are known. Can be added and used.

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 of Graft Copolymer (Ia):

45 parts by weight of polybutadiene latex (average particle size 0.3 μm) 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. 60 parts by weight of styrene and 40 parts by weight of acrylonitrile were added to the part and 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 added dropwise to 4% aqueous sulfuric acid solution heated to 90 ° C, precipitated, washed, dehydrated and dried to obtain a graft copolymer. The graft ratio of the copolymer obtained here was 50%, and the weight average molecular weight of the ungrafted acrylonitrile-styrene copolymer was 45,000.

Preparation of Graft Copolymer (Ib):

A rubber particle diameter of 0.3 μm was prepared in the same manner as in Ia, except that 40 parts by weight of a monomer mixture of styrene and acrylonitrile was used in 60 parts by weight of polybutadiene rubber.

Copolymer (IIa):

An acrylonitrile-styrene copolymer having a weight average molecular weight of 260,000 to 350,000 and an acrylonitrile content of 23 to 28% by weight was used.

Copolymer (IIb):

An acrylonitrile-styrene copolymer having a weight average molecular weight of 100,000 to 160,000 and an acrylonitrile content of 36 to 42% by weight was used.

Copolymer (IIc):

An acrylonitrile-styrene copolymer having a weight average molecular weight of 100,000 to 120,000 and an acrylonitrile content of 23 to 28% by weight was used.

Copolymer (IId):

An acrylonitrile-alphamethylstyrene copolymer having a weight average molecular weight of 100,000 to 160,000 and an acrylonitrile content of 23 to 28% by weight was used.

Copolymer (IIe):

An N-phenylmaleimide-styrene copolymer having a weight average molecular weight of 100,000 to 170,000 and an N-phenylmaleimide content of 40% by weight was used.

Preparation of Polymer (IIIa):

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, Then, 0.02 parts of vinyl mercaptan compound having the following structure was mixed with 0.5 parts of 2,2'-azobisisobutylonitrile as an initiator, and then the reactor was completely sealed, and then sufficiently stirred and dispersed, followed by increasing the internal temperature of the reactor. The temperature was raised and polymerization was performed at 75 ° C. for 6 hours. After the reaction was completed by cooling the inside of the reactor to room temperature, the obtained polymer was washed, dehydrated and dried to obtain a bead copolymer. The weight average molecular weight by GPC of the copolymer obtained here was 320,000.

Wherein R is-(C ₆ H ₄ )-(CH ₂ ) ₁₂ -and R ¹ is H.

Preparation of Copolymer (IIIb):

It was prepared in the same manner as in (IIIa) except that 0.06 parts of the same vinyl mercaptan compound as in (IIIa) was used.

Preparation of Copolymer (IIIc):

It was prepared in the same manner as in (IIIa) except that 0.1 part of the same vinyl mercaptan compound as in (IIIa) was used.

Example 1

The copolymers (I), (II) and (III) were mixed in the components and contents of Table 1, and 0.4 parts by weight of a conventional heat stabilizer and a lubricant were mixed with 100 parts by weight of the resin to form a twin screw extruder having a diameter of 40 mm. Pellets were prepared using. After manufacturing the compressed pellets of 400mm × 400mm × 2mm by using a press, the lattice of 50mm width and width was displayed on the prepared compression specimen, and then 300mm (L) × 30mm (W) × A vacuum molded article of 200 mm (H) was prepared, and the thickness of the intersection point of the lattice was measured with a thickness gauge with an accuracy of 1/100 mm for the vacuum molded article. The large minimum thickness and small standard deviation can be said to be excellent in vacuum forming, and the measured thickness and deviation are given in Table 2 together with general properties. In addition, the swell ratio and draw time were measured from a parison formed by extruding the prepared pellets at a cylinder temperature of 220 ° C. and a screw speed of 30 rpm using a blow molding machine having a diameter of 50 mm. The swelling ratio is defined as the diameter of the parison tip divided by the die diameter, and the draw time is defined as the time it takes for the parison to reach the ground, leaving a 1.2m high die from the ground. In general, the greater the swell ratio, the longer the draw time, the greater the strength of the parison and the better the moldability, the moldability evaluation results are shown in Table 2.

Example 2

The copolymers (I), (II) and (III) were mixed in the components and contents of Table 1, and were carried out in the same manner as in Example 1.

Example 3

The copolymers (I), (II) and (III) were mixed in the components and contents of Table 1, and were carried out in the same manner as in Example 1.

Example 4

The copolymers (I), (II) and (III) were mixed in the components and contents of Table 1, and were carried out in the same manner as in Example 1.

Comparative Example 1

The copolymers (I) and (III) were mixed with the components and contents shown in Table 1, and were carried out in the same manner as in Example 1.

Comparative Example 2

The copolymers (I) and (III) were mixed with the components and contents shown in Table 1, and were carried out in the same manner as in Example 1.

Comparative Example 3

The copolymers (I) and (III) were mixed with the components and contents shown in Table 1, and were carried out in the same manner as in Example 1.

TABLE 1

TABLE 2

The present invention has the effect of the invention capable of providing a styrene-based thermoplastic resin composition suitable for vacuum molding or blow molding as the drawing properties are good as shown in the results of Table 2.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (3)

Graft copolymer (I) formed by copolymerizing a vinyl cyanide compound (A) and an aromatic vinyl compound (S) with a rubbery polymer (B); Copolymer (II) consisting of the vinyl cyanide compound (A) and an aromatic vinyl compound (S); And a copolymer (III) having a nonlinear structure by copolymerizing the vinyl cyanide compound (A), the aromatic vinyl compound (S), and the vinyl mercaptan compound (M); And the content ratio of the copolymers (I), (II) and (III) is in the range of 25 to 40:25 to 40:25 to 50, and the weight average molecular weight of the copolymer (II) is 120,000 to It is in the range of 600,000, and the copolymer (III) contains 0.0001-5 parts by weight of a vinyl mercaptan compound (M), and has a weight average molecular weight of 180,000 or more and an intrinsic viscosity of 0.6 or more. The styrene-based thermoplastic resin composition of claim 1, wherein the vinyl-based mercaptan compound has a vinyl group copolymerizable with an aromatic vinyl compound or a cyanide compound and has a mulcaptan group. Wherein R ¹ is hydrogen or a methyl group, R is a phenyl group, halophenyl group, alkyl group, alkylphenyl group or alkylhalophenyl group, and may include an ester group or a sulfonic acid group. The copolymer (I) or (III) according to claim 1, wherein the copolymer (I) or (III) is another monomer capable of copolymerization with the vinyl cyanide compound (A) and the aromatic vinyl compound (S), such as an N-phenylmaleimide or methacrylic acid ester compound. (E) further contains a styrene-based thermoplastic resin composition.