KR100623009B1 - Method of preparing thermoplastic resin having improved weatherability and impact resistance - Google Patents

Abstract

The method for preparing a thermoplastic resin having improved weatherability and impact resistance according to the present invention is to prepare a mixed rubber latex by cohesion bonding 10 to 50 parts by weight of butadiene rubber and 50 to 90 parts by weight of an acrylic rubber, and aromatic vinyl to the mixed rubber latex. It is characterized by consisting of a step of graft polymerization by adding a monomer mixture consisting of a compound and a vinyl cyanide compound.

Weather resistance, impact resistance, thermoplastic resin composition, butadiene rubbery, acrylic rubbery, aromatic vinyl compound, vinyl cyanide compound

Description

Method of Preparing Thermoplastic Resin Having Improved Weatherability and Impact Resistance

Field of invention

The present invention relates to a method for producing a thermoplastic resin having improved weather resistance and impact resistance. More specifically, the present invention relates to a method for preparing a thermoplastic resin having improved weather resistance and impact resistance by graft polymerization using a mixed rubber latex obtained by physically cohesively bonding acrylic rubber and butadiene rubber with different physical and chemical properties. will be.

Background of the Invention

Generally, ABS resin is a copolymer of acrylonitrile monomer and butadiene monomer styrene monomer. They are in harmony with various physical properties such as stiffness, weather resistance, chemical resistance, impact resistance, glossiness, and moldability in ABS resin. In general ABS resin manufacturing process, butadiene monomer is polymerized through a conventional emulsion polymerization, and then a graft polymerization of a certain amount of styrene and acrylonitrile is carried out to compensate for a decrease in compatibility between butadiene rubber styrene and acrylonitrile. It is obtained through an extrusion process of mixing at a constant temperature with the styrene and the acrylonitrile copolymer obtained through dispersion polymerization or bulk polymerization.

Butadiene rubber in the ABS resin improves impact resistance, but in the overall ABS resin manufacturing process, the polymerization time is long because the polymerization process is made by the conventional emulsion polymerization method, and thus the ABS resin production time is influenced. Butadiene rubber should have a particle size of a predetermined size or more in order to exhibit impact resistance in the ABS resin, a long time polymerization reaction time is required to polymerize the butadiene rubber of a predetermined particle size or more through emulsion polymerization.

Butadiene rubber has the property of chemically double bonds and easily aging under the influence of oxygen or ultraviolet rays, thereby reducing weather resistance. In order to improve this, a method of adding a weathering stabilizer or the like during a graft polymerization process and an extrusion process is commonly used. However, the improvement effect is not so large that the typical ABS resin is limited to use indoors or indoors. In order to improve such weather resistance, there are conventionally known resin production methods using acrylic rubber.

Acrylic rubber-based resins are commonly referred to as ASA resins and consist of three components: acrylates, styrene, and acrylonitle, and because of their excellent weatherability, they are mainly used for outdoor applications. It is used in various fields such as parts, building materials, agricultural equipment, ASA / ABS two-layer sheet, profile extrusion, road signs, outdoor products, building materials, PVC, construction / interior, leisure / living goods, sporting goods, and automobile parts.

ASA-based thermoplastic resins are excellent in weathering discoloration, chemical resistance, thermal stability, etc., and are widely used in products such as satellite antennas, kayak paddles, chassis joiners, door panels, and side mirror housings. In particular, the demand for ASA resins for building materials has increased due to the recent regulations on the use of vinyl chloride resins and the advancement of the building materials market. As a result, the usage of the ASA resins as well as the existing chassis joiners is gradually increasing.

However, ASA resin has a very good weather stability while the impact resistance is weak, so the following methods are known to improve.

As a method for improving impact resistance, there are methods for adjusting the particle size of the acrylic rubber and adjusting the gel content. However, in the graft copolymerization process, it is difficult to control physical properties such as increasing coagulant, adjusting graft polymerization rate, and adjusting acrylic rubber content. There is a disadvantage that causes physical properties such as appearance and gloss after the process.

In addition, there is a method for improving the impact resistance by combining with butadiene-based rubber. In this method, butadiene-based rubber is used as a core or seed, and the shell layer is formed of acrylic rubber, followed by graft polymerization, acrylic rubber and butadiene-based rubber, and graft polymerization. And blended with the extruded ABS or ABS resin. However, these methods are difficult to control the efficiency and process operating conditions of the secondary polymerization of the seed polymerization process and the acrylic shell forming process, the graft rate difference between the acrylic rubber and butadiene rubber during graft polymerization, and difficult to control the graft rate There are problems such as ABS resin blending limitation due to deterioration of physical properties and weather resistance.

Accordingly, the present inventors attempted to improve weather resistance and impact resistance of the thermoplastic resin composition by performing grafting polymerization after acryl-based rubbery butadiene-based rubbery was physically chemically coagulated in the pre-graft polymerization step.

An object of the present invention is to provide a method for producing a thermoplastic resin with improved weather resistance.

Another object of the present invention is to provide a method for producing a thermoplastic resin having improved impact resistance by performing grafting polymerization after acryl-based rubbery butadiene-based rubbery is physically chemically coagulated in the pre-graft polymerization step.

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

Summary of the Invention

The method for preparing a thermoplastic resin having improved weatherability and impact resistance according to the present invention is to prepare a mixed rubber latex by cohesion bonding 10 to 50 parts by weight of butadiene rubber and 50 to 90 parts by weight of an acrylic rubber, and aromatic vinyl to the mixed rubber latex. It is characterized by consisting of a step of graft polymerization by adding a monomer mixture consisting of a compound and a vinyl cyanide compound.

Hereinafter, specific contents of the present invention will be described in detail below.

Detailed Description of the Invention

Butadiene Rubber

Butadiene-based rubber used in the present invention is prepared by a conventional emulsion polymerization method. The emulsifier uses at least one anionic emulsifier and a nonionic emulsifier. Synthesized rubber is in the form of latex, and the latex is polybutadiene polymer, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer butadiene-α-methylstyrene copolymer, butadiene-acrylate copolymer, butadiene-methacryl The rate copolymer etc. are not limited to these.

The butadiene-based rubber is in a latex state, each particle size is preferably in the range of 80 to 160 nm. If the particle size is less than 80 nm, the stability due to high viscosity in the manufacture of butadiene-based rubber is reduced, and due to the sudden increase in the number of butadiene-based rubber when mixed with the acrylic rubber, the physical property decreases during the graft polymerization after mixing with the acrylic rubber. Cause. When the particle size is larger than 160 nm, the production time of butadiene-based rubber is increased, and when mixing with the acrylic rubber and the acrylic coagulant, it is not uniformly mixed with the acrylic rubber and the coalescence due to the aggregation and diffusion between the butadiene-based rubber. Due to the occurrence of graft rate difference between butadiene-based rubber and acrylic rubber, physical properties are deteriorated.

The solid content of the butadiene-based rubbery is preferably 30 to 50% by weight. If the solid content is less than 30% by weight, it is disadvantageous for commercial production. If the solid content is more than 50% by weight, the polymerization stability is decreased and butadiene-based rubbery coagulation may occur, resulting in a decrease in uniformity when mixed with the acrylic rubbery.

In addition, the degree of gel content of the butadiene-based rubbery is preferably in the range of 70 to 90% by weight. If the gel content is less than 70% by weight, it may be difficult to handle due to the stickiness and high viscosity of the rubbery and may cause the problem of no filtering. If the gel content is more than 90% by weight, the swelling of the copolymerized monomers in the graft polymerization process If this is not done, hard core formation in rubbery material can be reduced.

Acrylic rubber

Acrylic rubber used in the present invention is prepared by a conventional emulsion polymerization method. The emulsifier uses one or more of the same anionic emulsifier and nonionic emulsifier as the butadiene-based rubbery preparation. The manufactured rubbery form is in a latex state and the acrylic rubber is a copolymer of an alkyl acrylate monomer and a monomer containing a small amount of unsaturated acid. As the alkyl acrylate monomer, monomers such as methyl acrylate, ethyl acrylate and butyl acrylate can be used, and as the monomer containing the unsaturated acid, a monomer having a carboxyl group is preferable. Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, methyl acrylic acid, itaconic acid, crotonic acid, fumaric acid, Methylene unsaturated carboxylic acids such as maleic acid.

The particle size of the acrylic rubber latex is preferably in the range of 30 to 200 nm, preferably in the range of 85 to 98% by weight of the alkyl acrylate monomer content. The monomer content containing unsaturated acid is preferably in the range of 2 to 15% by weight.

When the size of the acrylic rubber is less than 30 nm, the polymerization stability is lowered, copolymerization with the monomer containing unsaturated acid is not uniform, and uniformity is reduced when mixed with the butadiene rubber. When the size of the acrylic rubber is more than 200 nm, the content of unsaturated acid present in each particle interface is increased, and when mixed with the butadiene rubber, it may cause local large particle size of the butadiene rubber, thereby lowering the properties of the final product. .

If the alkyl acrylate monomer content is less than 85% by weight, the unsaturated acid-containing monomer content is relatively increased, thereby lowering the overall polymerization rate and increasing the content of the unsaturated acid present at the alkyl acrylate interface. Large chemical interactions cause localized large particle size. If the alkyl acrylate monomer content is more than 98% by weight, there is a problem in that the butadiene-based rubber and the acrylic rubber are graft-polymerized separately in the graft polymerization due to the weakening of the physicochemical interaction with the butadiene-based rubber. .

Preparation of Mixed Rubber Latex

The mixed rubbery latex of the present invention is prepared by adding and mixing the butadiene-based rubber having a particle size of 80 to 160 nm to the acrylic rubber having a particle size of 30 to 200 nm, and is prepared by physicochemical cohesion.

The mixing temperature of the two rubbers is preferably in the range of 40 to 80 ℃, butadiene rubber content is 10 to 50 parts by weight, acrylic rubber is preferably 50 to 90 parts by weight. Moreover, as for mixing time, 10 to 60 minutes are preferable.

In the mixing process, butadiene-based and acryl-based rubbers have a low homogenization rate at a temperature of less than 40 ° C. Therefore, a long time mixing process is required.

When the butadiene-based rubber content is less than 10 parts by weight, the weather resistance is good, but the effect of improving impact resistance is insignificant. When the butadiene-based rubber content is more than 50 parts by weight, weather resistance is deteriorated.

If the mixing time is less than 10 minutes, it is difficult to expect a homogeneous bonding between the two rubbers. If the mixing time is longer than 60 minutes, the creaming occurs due to the fusion between the two rubbers, the deterioration of latex stability, and the large cohesion behavior. .

Graft Polymerization Using Mixed Rubber Latex

A monomer mixture consisting of an aromatic vinyl compound and a vinyl cyanide compound is added to the mixed rubbery latex prepared above, and graft polymerization is performed in a conventional manner.

In an embodiment of the present invention, graft polymerization is performed by mixing 10-20 parts by weight of acrylonitrile and 30-40 parts by weight of styrene to 50-60 parts by weight of the mixed rubbery latex.

In the graft polymerization of the mixed rubber latex, a mixture of monomers composed of an aromatic vinyl compound and a vinyl cyanide compound is a monomer mixture of 30-40% of the total monomer mixture together with a molecular weight modifier, an emulsifier, a polymerization initiator, ion-exchanged water and a reducing agent. To the reactor, and after heating, the catalyst compound was added to form a first graft polymerization, and then a residual amount of the monomer mixture was gradually added for 2-3 hours to form a second graft polymerization. Specific examples of molecular weight regulators, emulsifiers, polymerization initiators and reducing agents used in graft polymerization in the present invention are described in Korean Patent Application No. 2002-28672, which is incorporated herein by reference.

The present invention will be further illustrated by the following examples, which are only described for the purpose of illustrating the present invention and are not intended to limit the protection scope of the present invention.

Example

The butadiene-based rubber and acrylic rubber used in Examples 1-3 are as follows.

Butadiene Rubber

A rubbery latex having a size of an average particle diameter of 120 nm prepared by a conventional emulsion polymerization method was used. The particle size was analyzed by CHDF-1100 (particle size analyzer).

Acrylic rubber

20 parts by weight of butyl acrylate, 0.4 parts by weight of tertiary dodecyl mercaptan, 1.2 parts by weight of sodium dodecyl benzenesulfonate, 0.1 parts by weight of sodium hydroxide, 0.7 parts by weight of potassium carbonate and 160 parts by weight of ion-exchanged water to the reactor After the temperature was raised to 60 ° C., 0.25 parts by weight of potasulfur sulfate was added to carry out the first polymerization for 1 hour. Thereafter, 60 parts by weight of butyl acrylate, 17 parts by weight of ethyl acrylate, and 3 parts by weight of methacrylic acid were mixed to raise the reactor temperature to 70 ° C., followed by secondary polymerization while introducing into the reactor for 3 hours. The reactor was maintained at 70 ° C. for 1 hour after the second polymerization. The average particle size of the prepared acrylic rubber was analyzed by CHDF-1100 (particle size analyzer) and found to have a size of 150 nm.

Example 1

Manufacture Mixed Rubbery Latex

85 parts by weight of acrylic rubber and 50 parts by weight of ion-exchanged water were added to the reactor and the reactor was kept at 55 ° C. while stirring at 100 rpm. Then, 15 parts by weight of butadiene-based rubber was added for 15 minutes, and the temperature was maintained for 30 minutes. The mixed rubbery latex having a particle size of 190 nm was prepared.

Graft polymerization

50 parts by weight of the mixed rubber latex prepared above in the graft polymerization reactor, 3.75 parts by weight of acrylonitrile monomer, 11.25 parts by weight of styrene monomer, 0.09 parts by weight of terdodosylmercaptan, 0.1 part by weight of cumene hydroperoxide, potassium stearate After adding 0.2 parts by weight, 0.3 parts by weight of sodium hydroxide and 140 parts by weight of ion-exchanged water, the temperature of the reactor was increased to 60 ° C, 0.003 parts by weight of ferrous sulfate and 0.15 parts by weight of tetrasodium parophosphate were added. Graft polymerization was performed.

The secondary graft polymerization was continuously performed immediately after the reactor temperature reached 70 ° C. due to the heat of polymerization generated during the first graft polymerization. 8.75 parts by weight of acrylonitrile monomer, 26.25 parts by weight of styrene monomer and 0.2 parts by weight of tertiary dedecylmercaptan were mixed and stirred in the primary graft polymer, and 0.22 parts by weight of cumene hydroperoxide was added to the reactor at a constant rate for 2 hours. The secondary polymerization was carried out to obtain graft polymer powder.

Example 2

A mixed rubber latex was prepared in the same manner as in Example 1, except that 70 parts by weight of the acrylic rubber and 30 parts by weight of the butadiene rubber were used. The particle size of the prepared mixed rubbery latex was 186 nm, and then the graft polymerization was performed in the same manner as in Example 1.

Example 3

A mixed rubber latex was prepared in the same manner as in Example 1, except that 55 parts by weight of the acrylic rubber and 45 parts by weight of the butadiene rubber were used. The particle size of the prepared mixed rubbery latex was 179 nm, and then the graft polymerization was performed in the same manner as in Example 1.

Comparative Example 1

Graft polymerization was carried out in the same manner as in Example 1, using 50 parts by weight of butadiene rubber ( average particle size 265 nm) prepared through conventional emulsion polymerization without using a mixed rubbery latex.

Comparative Example 2

Graft polymerization was carried out in the same manner as in Example 1 without using a mixed rubbery latex and using 50 parts by weight of an acrylic rubber (average particle size 211 nm) which was not copolymerized with a monomer including an unsaturated acid prepared through conventional emulsion polymerization.

 Comparative Example 3

 Graft polymerization was carried out in the same manner as in Example 1, using a rubbery latex obtained by mixing 30 parts by weight of butadiene-based rubber of Comparative Example 1 and 20 parts by weight of acrylic rubber of Comparative Example 2.

Comparative Example 4

 Graft polymerization was performed by mixing 20 parts by weight of butadiene rubber of Comparative Example 1 with 30 parts by weight of acrylic rubber (average particle diameter of 220 nm) having an unsaturated acid content of 1 part by weight of the interface.

The coagulant content, graft ratio and particle size of the graft polymer prepared in Examples 1-3 and Comparative Examples 1-4 are shown in Table 1 below.

Coagulum Graft rate Particle diameter Example One 0.10% 85% 230 nm 2 0.15% 85% 225 nm 3 0.12% 85% 224 nm Comparative Example One 0.17% 91% 285nm 2 0.30% 83% 230 nm 3 7.90% 93% 320 nm 4 4.42% 94% 315nm

Preparation and Evaluation of ABS Resins

The resin composition was prepared by the following method in order to evaluate the physical properties of the five graft polymer powders prepared in Examples and Comparative Examples in the resin.

30 parts by weight of the graft polymer prepared above, 27 parts by weight of acrylonitrile, a weight average molecular weight of 120,000, 70 parts by weight of SAN copolymer having a molecular weight distribution of 1.88, 1 part by weight of calcium stearate as a stabilizer, and ethylene bis steroid 1 part by weight of mixed extrusion and injection molding to prepare a test piece for measuring the physical properties. Each prepared specimen was evaluated for physical properties according to the following method, and is shown in Table 2 below.

(1) Impact strength: evaluated by Izod impact strength (1/4 ″) according to ASTM D256.

(2) Flow index: measured according to ASTM D1238.

(3) Glossiness (Gloss%): The measurement angle was measured at 60 ° according to ASTM D523.

(4) Yellowness: measured according to ASTM D1925.

(5) Whiteness: measured according to ASTM D1925.

(6) Color change: measured according to ASTM D1925.

Properties Example Comparative Example One 2 3 One 2 3 4 Izod impact strength 19 21 23 22 7 14 15 Flow index 3 3 3 3 3 0.9 1.2 Glossiness 90 90 90 90 90 56 62 Yellow road 18 19 22 25 18 18 17 Whiteness 80 78 75 71 80 80 81 Discoloration degree 0.7 2.2 4.1 10.0 0.3 5.0 4.9

As shown in Table 2, the ABS resin prepared using butadiene and acrylic mixed rubber latex was excellent in terms of discoloration and impact resistance. On the other hand, ABS resin produced using only butadiene-based rubber appeared high discoloration, ABS resin produced using only the acrylic rubber can be seen that the impact strength is significantly reduced.

 In addition, in Comparative Example 4, it can be seen that when the butadiene-based rubber and the acrylic rubber are not properly mixed, graft polymerization is not easy and physical properties such as fluidity decrease are generated.

The present invention is to prepare a thermoplastic resin composition having improved weather resistance and impact resistance by performing a graft polymerization after the butadiene-based rubber and 10 to 50 parts by weight and 50 to 90 parts by weight of the acrylic rubber 50 to 90 parts by weight before the graft polymerization. It has the effect of the invention providing a method.

Simple modifications and variations of the present invention can be readily used by those skilled in the art, and all such variations or modifications can be considered to be included within the scope of the present invention.

Claims (7)

A butadiene-based rubber, 10 to 50 parts by weight and 50 to 90 parts by weight of the acrylic rubber cohesive bonding to produce a mixed rubber latex, characterized in that for producing a thermoplastic resin. The method of claim 1, wherein the acrylic rubber is a copolymer of an alkyl acrylate monomer and a monomer containing an unsaturated acid. The method of claim 2, wherein the acrylic rubber has an alkyl acrylate monomer content of 85 to 98% by weight, and a monomer content containing unsaturated acid is 2 to 15% by weight. The method for producing a thermoplastic resin composition according to claim 1, wherein the butadiene-based rubbery and acryl-based rubbery cohesive bond is stirred and mixed for 10 to 60 minutes in a temperature range of 40 to 80 ° C.   The method for producing a thermoplastic resin according to claim 1, wherein the butadiene rubbery particle size is 80 to 160 nm, and the acrylic rubbery particle size is 30 to 200 nm.  The method of claim 1, further comprising graft polymerization by adding a monomer mixture composed of an aromatic vinyl compound and a vinyl cyanide compound to the mixed rubbery latex.  The method of claim 6, wherein the thermoplastic resin is polystyrene resin (PS resin), acrylonitrile-butadiene-styrene copolymer resin (ABS resin), acrylonitrile-styrene copolymer resin (SAN resin), rubber-modified polystyrene resin ( HIPS), acrylonitrile-styrene-acrylate copolymer resin (ASA resin), methyl methacrylate-butadiene-styrene copolymer resin (MBS resin), acrylonitrile-ethylacrylate-styrene copolymer resin (AES resin) ), Polycarbonate resin (PC), polyphenylene ether resin (PPE), polyethylene resin (PE), polypropylene resin (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), polyamide (PA) -based resin and at least one mixture selected from the group consisting of copolymers of these resins is added to the kneading extrusion Method for producing a thermoplastic resin, characterized in that.