KR100450110B1 - Thermoplastic Resin Compositions With Good Vacuum Formability - Google Patents

Abstract

The thermoplastic resin composition excellent in vacuum forming of the present invention is (A) a weight average molecular weight of 50,000 to 70 to 30% by weight of a butadiene-based rubber mixture of an aromatic vinyl monomer and a vinyl cyanide monomer mixture to 30 to 70% by weight of 50,000 20 to 50% by weight of graft copolymer having a content of 100,000 to 100,000; (B) 40 to 70% by weight of a styrene-acrylonitrile copolymer having a weight average molecular weight of 100,000 to 300,000 prepared by copolymerizing 50 to 90% by weight of an aromatic vinyl monomer and 50 to 10% by weight of a vinyl cyanide monomer; And (C) 0.01-5 parts by weight of polyfunctional multantan and 0.005-5 parts by weight of polyfunctional acrylic monomer based on 100 parts by weight of the monomer mixture consisting of 50 to 90% by weight of an aromatic vinyl monomer and 50 to 10% by weight of a vinyl cyanide monomer. It is made of 0.1 to 30% by weight of the copolymer having an ultra-high molecular weight of the nonlinear structure prepared by adding a.

Description

Thermoplastic Resin Compositions With Good Vacuum Formability

Field of invention

The present invention relates to a styrene-based thermoplastic resin composition excellent in vacuum formability. More specifically, the present invention relates to a styrene-based thermoplastic resin composition in which stretching properties are improved by using ultra-high molecular weight styrene-acrylonitrile (SAN) in which a polyfunctional acrylic monomer and a polyfunctional multantan are introduced.

Background of the Invention

Rubber-reinforced styrenic resins, particularly acrylonitrile-butadiene-styrene copolymers (ABS) resins are widely used in electrical and electronic parts, office equipment, automobile parts, etc. because of their excellent mechanical properties, ease of molding, and beautiful appearance. Most of these molded products are manufactured by injection molding, and in the case of increasing the size of the molded product or having a curved surface on the outside of the molded product, it is manufactured by vacuum molding.

Vacuum molding is a sheet extruded resin to prepare a sheet of sheet, and then the sheet is heat-softened in a vacuum molding machine, and then vacuum or pressure and vacuum are simultaneously applied to obtain a product of a desired shape by closely contacting the softened sheet to a mold. It is a kind of plastic molding method. This method is a molding method using the stretching property of the resin, wherein the stretching property of the resin indicates the degree of resistance when the resin is stretched or expanded by an external force at a high temperature at which the flow is possible. Such high temperature environment can be easily encountered in processes such as vacuum forming, blow molding, film forming, etc. At this time, the resin having good stretching characteristics is resistant and uniform evenly distributed even if the thickness becomes too thin or angular. Can be maintained. In general, the stretching property of the resin is closely related to the chemical structure of the resin. For olefin resins such as polyolefins, when the resin structure is branched, the stretching property is better than that of the linear structure. It is known that a molded article having a strong and uniform thickness distribution can be obtained.

Vacuum forming is widely used to make inner sheets of refrigerators and generally uses acrylonitrile-butadiene-styrene copolymer (ABS resin). This is because ABS resin not only has good mechanical properties and processability but also has excellent appearance and gloss. The ABS resin is a resin composition (g-ABS) obtained by graft copolymerization of a monomer mixture of 10-50 parts by weight of acrylonitrile and 50-90 parts by weight of styrene in the presence of polybutadiene rubber. It refers to a resin composition obtained by mixing 50 parts by weight of acrylonitrile-styrene copolymer (hereinafter referred to as SAN).

However, in the case of the conventional general ABS resin, due to the deterioration of the stretching characteristics, since the thickness variation for each part occurs during vacuum molding, a very thin part is formed locally. These thin parts have a problem that many breakages occur easily due to residual stress and external impact during or after assembling the refrigerator.

U.S. Patent No. 4,918,159 discloses a method for producing a styrene resin having a nonlinear structure using a polyfunctional mulcaptan in a rubber-reinforced styrene resin. However, when the polyfunctional multicaptan is used alone, there is a problem in controlling the polymerization reaction such that the reactivity is slow and the dispersion system is very unstable as the polymerization reaction proceeds, thereby causing the entire polymerization system to harden.

The present applicant has applied for a method of using a copolymer composition of an ultra high molecular weight vinyl cyanide compound and an aromatic vinyl compound in order to improve the stretching property of the sheet and induce uniform stretching for each part during vacuum molding (Korean patent) Application 2000-83855).

In addition, Korean Patent Application Nos. 97-51221 and 97-51222 have developed and applied a method for dramatically improving the existing stretching characteristics using a copolymer composition of a nonlinear vinyl cyanide compound and an aromatic vinyl compound. However, when the copolymer composition of the vinyl cyanide compound and the aromatic vinyl compound having such an ultra high molecular weight or nonlinear structure can be used to improve the stretching characteristics and reduce the thickness deviation, the extruder load during compounding and sheet production due to the deterioration of fluidity The increase in the productivity is lowered, the strength of the product is lowered, and there is a disadvantage that the change of color occurs.

In order to solve this problem, the present inventors use a non-linear ultra high molecular weight SAN copolymer in which a multifunctional mercaptan and an acrylic polyfunctional monomer are introduced, and thus, a resin composition having excellent stretching and flow characteristics without causing gelation. It is early to develop.

An object of the present invention is to provide a thermoplastic resin composition excellent in vacuum forming because there is little thickness knitting phenomenon after vacuum molding.

Another object of the present invention is to provide a thermoplastic resin composition having improved stretching properties.

Still another object of the present invention is to provide a thermoplastic resin composition in which fluidity is not lowered during the manufacturing process.

The above and other objects of the present invention can be achieved by the present invention described below. Hereinafter, the content of the present invention will be described in detail.

The ABS resin composition of this invention consists of (A) graft copolymer, (B) acrylonitrile-styrene (SAN) copolymer, and (C) ultra high molecular weight SAN copolymer which has a nonlinear structure. These components will be described in detail below.

(A) Graft Copolymer

The graft copolymer according to the present invention is a conventional emulsified graft by adding 70 to 30% by weight of a monomer mixture of styrene and acrylonitrile to 30 to 70% by weight of polybutadiene latex having a rubber particle size of 1000 to 5000Å It may be prepared by a polymerization method. The graft copolymer has a graft ratio of 50 to 100% and a weight average molecular weight of the grafted resin is 50,000 to 100,000. It is preferable to use about 20 to 50% by weight of the copolymer based on the final resin composition.

(B) Styrene-Acrylonitrile (SAN) Copolymer

The SAN copolymer according to the present invention is prepared by copolymerizing 50 to 90% by weight of aromatic vinyl monomer and 10 to 50% by weight of unsaturated nitrile monomer by conventional bulk polymerization or suspension polymerization. As the unsaturated nitrile monomer, a vinyl cyanide monomer is preferable. The copolymer is a commonly used SAN copolymer having a PS reduction weight average molecular weight of 100,000 to 300,000, preferably 40 to 70% by weight based on the final resin composition.

(C) Ultra High Molecular Weight SAN Copolymer

The ultra-high molecular weight SAN copolymer is 0.01-5 parts by weight of polyfunctional multantan and 0.005-5 parts by weight of a multi-tube based on 100 parts by weight of a monomer mixture composed of 50 to 90% by weight of an aromatic vinyl monomer and 10 to 50% by weight of a vinyl cyanide monomer. It is a copolymer having an ultra-high molecular weight of a nonlinear structure prepared by adding a functional acrylic monomer.

The ultra high molecular weight SAN copolymer according to the present invention is characterized in that the weight average absolute molecular weight by light scattering method is at least 300,000 or more.

Examples of the polyfunctional acrylic monomers include ethylene dimethacrylate, diethylene glycol methacrylate, triethylene glycol dimethacrylate, trimethylene propane trimethacrylate, 1,3-butanediol methacrylate, and 1,6-hexane. Diol dimethacrylate, allyl acrylate, etc. are mentioned.

The content of the multifunctional acrylate monomer is 0.005-5 parts by weight, more preferably 0.01-3 parts by weight based on 100 parts by weight of the aromatic vinyl monomer and the vinyl cyanide monomer mixture. When the total content of the multifunctional acrylate monomer is less than 0.005 parts by weight, the effect of improving the stretching property is not obvious. When the total content of the multifunctional acrylate monomer is greater than 5 parts by weight, the gelation reaction proceeds when the copolymer is formed and the surface of the gel of the melt is formed. Occurs in the phase.

The multifunctional multantan is a compound having three or more -SH groups, and there are trivalent and tetravalent multantans.

Examples of the trifunctional functional mercaptan include trimethylpropane tri (3-mulcetopropionate), trimethylpropane tri (3-mercaptoacetate), trimethylpropane tri (4-mercaptobutanate), and trimethylpropane tri (5- Mercaptopentanate), trimethylpropane tri (6-mercaptohexaonate), and the like.

Examples of the tetravalent functional mercaptan include pentaerythryl tetrakis (2-mercaptoacetate), pentaerythryl tetrakis (3-mercaptopropionate), pentaerythryl tetrakis (4-mercaptobutanate), Pentaerythryl tetrakis (5-mercaptopentanate), pentaerythryl tetrakis (6-mercaptohexanate), and the like.

The polyfunctional mercaptan that can be used in the present invention may be used alone or in combination of two or more of the above compounds. In the present invention, the multifunctional mercaptan is used in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the aromatic vinyl monomer and the vinyl cyanide monomer mixture.

In the present invention, a method for preparing the ultra-high molecular nonlinear copolymer may be a known method, that is, emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization. The ultrahigh molecular nonlinear copolymers of the present invention are blended with the linear copolymer in an appropriate proportion, rather than alone with the rubber graft polymer, to form a matrix of the final resin composition, eg, an ABS resin.

In addition to the above components, auxiliary components such as known heat stabilizers and lubricants may be added to the resin composition of the present invention.

The present invention may be further embodied by the following examples, which are for illustrative purposes of the present invention and are not intended to limit the scope of protection defined by the appended claims.

Example

Preparation and specifications of (A) graft copolymer, (B) SAN copolymer, and (C) ultra high molecular weight SAN copolymer used in the following Examples and Comparative Examples are as follows.

(A) Graft Copolymer

Butadiene rubber latex having a rubber particle diameter of 0.3 μm was added so that the content of the butadiene rubber was 50 wt% based on the entire monomer, 150 parts by weight of deionized water, 0.9 parts by weight of rosin soap, 0.3 parts by weight of cumene hydroperoxide, 0.2 parts by weight of mercaptan-based chain transfer agent and 0.3 parts by weight of glucose were added and the internal temperature was maintained at 70 ° C. To this, 35 parts by weight of styrene and 15 parts by weight of acrylonitrile were added dropwise for 3 hours, followed by polymerization by a redox initiator to prepare styrene-acrylonitrile-butadiene graft copolymer latex. It was solidified in 1.5% magnesium sulfate aqueous solution and dried to prepare a powdered styrene-acrylonitrile-butadiene graft copolymer resin.

(B) linear SAN copolymer

Cheil Industries, Ltd. SAN HR-5330 was used.

(C) Nonlinear Ultra High Molecular Weight SAN Copolymer

In a stainless autoclave equipped with a stirrer, 71% by weight of styrene monomer, 29% by weight of acrylonitrile monomer, 150 parts by weight of ion-exchanged water, 0.5 parts by weight of potassium triphosphate, trimethylpropane trivalent with polyfunctional multantan Mulchtopropionate) 0.3 parts by weight, 0.15 parts by weight of a polyfunctional acrylate monomer, and 0.3 parts by weight of 2,2'-azobisisobutylonitrile (AIBN) as an initiator were mixed, and then the reactor was completely sealed. Then, the mixture was sufficiently stirred to disperse, and then the internal temperature of the reactor was raised to 70 ° C. to proceed with polymerization for 5 hours. Thereafter, the inside of the reactor was cooled to room temperature to terminate the reaction, and the obtained polymer was washed, dehydrated and dried to obtain a bead-like copolymer.

Example 1

A graft copolymer (A) prepared above, a linear styrene-acrylonitrile copolymer (B), and a nonlinear ultra high molecular weight copolymer (C) using ethylene glycol dimethacrylate as a polyfunctional acrylate monomer were obtained. The mixture was mixed at a ratio of 50:20, and 0.4 parts by weight of a phenolic antioxidant, a thermal stabilizer, and magnesium stearate, a lubricant, was mixed with 100 parts by weight of the resin, to prepare pellets using a twin screw extruder having a diameter of 40 mm. It was. After producing the compressed pellets of 400mm × 400mm × 2mm by using the prepared pellets, the lattice of 50mm width and width was displayed on the prepared compression specimens, and then 300mm (L) × 30mm (W) through the vacuum molding machine. A physical specimen of 200 mm (H) was prepared.

Example 2

It was carried out in the same manner as in Example 1 except that allyl acrylate was used as the polyfunctional acrylate monomer.

Example 3

The same procedure as in Example 1 was carried out except that 1,3-butanediol methacrylate was used as the polyfunctional acrylate monomer.

Example 4

The same procedure as in Example 1 was carried out except that 1,6-butanediol methacrylate was used as the polyfunctional acrylate monomer.

Comparative Example

A resin composition prepared by mixing the graft copolymer (A) and the copolymer (B) in a ratio of 30:70 without using the nonlinear copolymer (C) was used.

Table 1 shows the physical properties of the specimens prepared in Examples 1-4 and Comparative Examples.

Example Comparative example One 2 3 4 Multifunctional Monomer Ethylene Glycol Dimethacrylate Allyl acrylate 1,3-butanediol methacrylate 1,6-butanediol methacrylate - THF Solubility Available Available Available Available - Weight average molecular weight (× 1000) 680 830 610 530 - Thickness (mm) 0.59 0.62 0.52 0.49 0.17 Standard deviation (mm) 0.11 0.12 0.12 0.17 0.36 Swellby 1.9 1.8 1.9 1.7 1.2 Draw time (sec) 57 63 59 55 35

* Property evaluation

(1) Evaluation of the formation of insoluble gel in the beads of the nonlinear ultra high molecular weight copolymer (C) was evaluated by solubility test for THF (tetrahydrofuran).

(2) The weight average absolute molecular weight of the nonlinear ultrahigh molecular weight copolymer (C) was measured by the light scattering method.

(3) Evaluation of vacuum forming

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 Swell ratio and draw time: The swell ratio and draw time were measured from a ferrison formed by extruding the manufactured 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. Swellby is defined as the diameter of the parison tip divided by the die diameter, and draw time is defined as the time it takes for Ferrison to leave the die 1.2 meters high from the ground and reach the ground. In general, the greater the swell ratio, the longer the draw time, the greater the parison's strength and the better formability.

From the results of Table 1, the resin composition to which the non-linear high molecular weight styrene-acrylonitrile copolymer prepared using the multifunctional acrylate monomer of the present invention is applied, is compared with the resin composition to which the non-linear ultra high molecular weight copolymer is not applied. It can be seen that it shows a significantly improved vacuum forming.

The present invention provides a thermoplastic resin composition suitable for vacuum forming of sheets requiring uniform stretching by improving the stretching characteristics of the resin composition by using a SAN having ultra high molecular weight in which a polyfunctional acrylate monomer and a polyfunctional mercaptan are introduced. Has the effect of providing.

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 (4)

(A) 20 to 50 wt% of a graft copolymer having a weight average molecular weight of 50,000 to 100,000 prepared by graft polymerization of 70 to 30 wt% of an aromatic vinyl monomer and a vinyl cyanide monomer mixture on 30 to 70 wt% of butadiene rubber ; (B) 40 to 70% by weight of a styrene-acrylonitrile copolymer having a weight average molecular weight of 100,000 to 300,000 prepared by copolymerizing 50 to 90% by weight of an aromatic vinyl monomer and 50 to 10% by weight of a vinyl cyanide monomer; And (C) 0.01-5 parts by weight of polyfunctional multantan and 0.005-5 parts by weight of polyfunctional acrylic monomer based on 100 parts by weight of the monomer mixture consisting of 50 to 90% by weight of an aromatic vinyl monomer and 50 to 10% by weight of a vinyl cyanide monomer. 0.1 to 30% by weight of a copolymer having a super high molecular weight of a nonlinear structure prepared by injection; Thermoplastic resin composition excellent in vacuum forming, characterized in that consisting of. The thermoplastic resin composition as claimed in claim 1, wherein the weight average absolute molecular weight of the copolymer (C) having a non-linear ultra high molecular weight is at least 300,000 by light scattering. The method of claim 1, wherein the multifunctional acrylic monomer is ethylene dimethacrylate, diethylene glycol methacrylate, triethylene glycol dimethacrylate, trimethylene propane trimethacrylate, 1,3-butanediol methacrylate , 1,6-hexanediol dimethacrylate, allyl acrylate thermoplastic resin composition excellent in vacuum forming, characterized in that selected from the group consisting of. The method of claim 1, wherein the multifunctional multantan is trimethyl propane tri (3- multo to propionate), trimethyl propane tri (3- mercapto acetate), trimethyl propane tri (4- mulcapto butanate), trimethyl propane Tri (5-mercaptopentanate), trimethylpropane tri (6-mercaptohexaonate), pentaerythryl tetrakis (2-mercaptoacetate), pentaerythryl tetrakis (3-mercaptopropionate) , Pentaerythryl tetrakis (4-mercaptobutanate), pentaerythryl tetrakis (5-mercaptopentanate), pentaerythryl tetrakis (6-mercaptohexanate) Thermoplastic resin composition excellent in vacuum forming.