KR20030040879A - Thermoplastic resin composition having improved weld-strength - Google Patents

Abstract

PURPOSE: A thermoplastic resin composition is provided, to improve the hot melt deposition, thereby enhancing the adhesive power and the adhesive strength with other plastic resin and the releasability from metal. CONSTITUTION: The thermoplastic resin composition comprises 20-40 parts by weight of a graft acrylonitrile-butadiene-styrene copolymer; 60-80 parts by weight of a heat resistant copolymer; and 1-5 parts by weight of a low molecular weight acryl-based additive. Preferably the graft acrylonitrile-butadiene-styrene copolymer is obtained by grafting an aromatic vinyl compound and a cyano vinyl compound onto a conjugated diene rubber latex; the heat resistant copolymer is a copolymer of α-methylstyrene and acrylonitrile; and the low molecular weight acryl-based additive has a molecular weight of 1,000-20,000.

Description

Thermosetting resin composition excellent in thermal adhesion {THERMOPLASTIC RESIN COMPOSITION HAVING IMPROVED WELD-STRENGTH}

The present invention relates to a thermoplastic resin composition, and more particularly, to a thermoplastic resin composition having excellent heat weldability.

Acrylonitrile-butadiene-styrene (hereinafter referred to as "ABS") thermoplastic resin is a material widely used in various office equipment, electrical, electronic parts, automotive interior materials, etc., due to its excellent physical properties such as impact resistance, chemical resistance, and molding processability. In order to be used in these electrical and electronic products have to have heat resistance, various methods for imparting heat resistance to the ABS resin has been studied.

As one of methods for imparting heat resistance to ABS resins, a method of kneading a heat resistant copolymer into a graft ABS polymer to produce a heat resistant ABS resin has been used. The method of manufacturing the heat-resistant ABS resin is a method of manufacturing by replacing part or all of the styrene used in the manufacture of the heat-resistant copolymer for kneading with α-methylstyrene having excellent heat resistance (US Pat. Nos. 3,010,936 and 4,659,790), Malay Method for producing by including a mid compound (Japanese Patent Laid-Open No. 58-206657, No. 63-162708, No. 63-235350 and US Pat. No. 4,757,109), Method of kneading with polycarbonate resin, Method of filling inorganic material Etc. are known.

Heat-resistant ABS resin has many steps to apply the product by post-processing after injection molding, it should be excellent in this post-processing. In particular, in order to be used for automotive back lamp housing, the heat adhesion with plastic for back lamp, ie polymethyl methacrylate, should be excellent. Therefore, the demand for a heat-resistant ABS resin excellent in such post-processing properties, in particular heat welding is increasing.

In order to solve the problems of the prior art, it is an object of the present invention to provide a thermoplastic resin composition excellent in heat adhesion.

The present invention to achieve the above object, a) graft ABS polymer; b) heat resistant copolymers; And c) provides a thermoplastic resin composition comprising a low molecular weight acrylic additive.

Hereinafter, each component of the thermoplastic resin composition of the present invention will be described in detail.

a) graft ABS polymer

The graft ABS polymer is prepared by graft polymerization of an aromatic vinyl compound and a vinyl cyanide compound on a conjugated diene rubber latex. The conjugated diene rubber latex uses a large diameter rubber latex prepared by preparing a small diameter rubber latex and then fusion.

The particle diameter and gel content of conjugated diene rubber latex used in the manufacture of graft ABS polymer have a great influence on the impact strength and processability of the resin. In general, the smaller the particle diameter of the rubber latex, the lower the impact resistance and workability, and the larger the particle diameter, the better the impact resistance. The lower the gel content, the more the monomer swells in the rubber latex and the polymerization takes place, thereby increasing the apparent particle size, thereby improving the impact strength. However, the higher the content of the rubber latex and the larger the particle size, there is a problem that the graft rate is lowered. The graft rate greatly affects the physical properties of the graft ABS polymer. When the graft rate is lowered, there are many rubber grafts that are not grafted.

Therefore, a method for producing conjugated diene rubber latex having an appropriate particle diameter and gel content is important, and a method for increasing the graft ratio when grafting an aromatic vinyl compound and a vinyl cyanide compound to a large diameter rubber latex is important.

Hereinafter, the manufacturing process of the graft ABS copolymer resin will be described in detail for each step by dividing the manufacturing process of the small-diameter rubber latex, the manufacturing process of the large-diameter rubber latex, and the graft polymerization process.

Manufacturing Process of Small Diameter Rubber Latex

The small-diameter rubber latex used in the present invention is a conjugated diene polymer, the particle diameter is preferably 600 Pa to 1500 Pa, the gel content is 70% to 95%, the swelling index is preferably 12 to 30. If the gel content exceeds 95%, the impact strength is lowered, if less than 70% has a problem that the thermal stability is lowered.

Small diameter rubber latex is 100 parts by weight of conjugated diene, 1 to 4 parts by weight of emulsifier, 0.1 to 0.6 parts by weight of polymerization initiator, 0.1 to 1.0 parts by weight of electrolyte, 0.1 to 0.5 parts by weight of molecular weight regulator, 90 to 130 parts by weight of ion-exchanged water. The reaction is carried out at 50 ° C. to 65 ° C. for 7 to 12 hours, followed by further batch administration of 0.05 to 1.2 parts by weight of a molecular weight modifier to prepare at 55 to 70 ° C. for 5 to 15 hours.

The emulsifiers include alkyl aryl sulfonates, alkali metal alkyl sulfates, sulfonated alkyl esters, fatty acid soaps, alkali salts of rosin acid, and the like, or may be used alone or in admixture of two or more thereof.

A water-soluble persulfate or a peroxy compound can be used as the polymerization initiator, and an oxidation-reduction system can also be used. The most suitable water-soluble persulfates are sodium and potassium persulfates, and fat-soluble polymerization initiators include cumenehydro peroxide, diisopropyl benzenehydroperoxide, azobis isobutylnitrile, tertiary butyl hydroperoxide, paramethane hydroperoxide, Benzoyl peroxide etc. can be used individually or in mixture of 2 or more types.

As the electrolyte, KCl, NaCl, KHCO ₃ , NaHCO ₃ , K ₂ CO ₃ , Na ₂ CO ₃ , KHSO ₃ , NaHSO ₃ , K ₄ P ₂ O ₇ , K ₃ PO ₄ , Na ₃ PO ₄ , K ₂ HPO ₄ , Na ₂ HPO ₄ and the like can be used alone or as a mixture of two or more thereof.

Mercaptans are mainly used as said molecular weight regulator.

The polymerization temperature is very important for adjusting the gel content and swelling index of the rubber latex, and the choice of initiator should also be considered.

<Large Diameter Rubber Latex Manufacturing Process (Small Diameter Rubber Latex Fusion Process)>

Since the large-diameter rubber latex particle diameter imparts high impact to the thermoplastic resin, its preparation is very important, and the particle diameter required for satisfying the physical properties in the present invention is preferably about 2500 mm to 5000 mm.

The manufacturing process of large diameter rubber latex is as follows.

The particle size was 600 ~ 1500Å, gel content 70% to 95%, swelling index 12 to 30 parts of small diameter rubber latex to 2.5 parts by weight of the aqueous solution of acetic acid was slowly administered for 1 hour to enlarge the particles and then stirred To stop the particle diameter is 2500Å to 5000Å, the gel content is 70% to 95% and the swelling index is fused to 12 to 30 to prepare a large diameter conjugated diene rubber latex.

<Graft polymerization process>

A graft ABS polymer is prepared by graft copolymerizing an aromatic vinyl compound and a vinyl cyanide compound on the large-diameter conjugated diene rubber latex prepared by the above method.

The graft polymerization process for preparing the graft ABS polymer includes 40 to 70 parts by weight of large-diameter rubber latex, 15 to 40 parts by weight of aromatic vinyl compound, 5 to 20 parts by weight of vinyl cyanide compound, 0.2 to 0.6 parts by weight of emulsifier, and molecular weight regulator 0.2 To 0.6 parts by weight and 0.1 to 0.5 parts by weight of the polymerization initiator to graft copolymerize.

The aromatic vinyl compound includes styrene, α-methylstyrene, ο-ethylstyrene, p-ethylstyrene, vinyltoluene, derivatives thereof, and the like. The vinyl cyanide compound is acrylonitrile, methacrylonitrile, ethacrylonitrile. And derivatives thereof.

The temperature of the polymerization reaction is suitable 45 ℃ to 80 ℃ and the polymerization time is preferably 3 to 5 hours.

The method of adding each component in the graft polymerization may be a method of collectively administering each component, a multi-step divided administration method, or a continuous administration method. In order to improve the graft rate and minimize the formation of coagulated products, a multi-step divided administration method or a continuous method may be employed. The method of administration is preferred.

The emulsifiers used in the polymerization reaction are alkylaryl sulfonates, alkali methylalkyl sulfates, sulfonated alkyl esters, fatty acid soaps, alkali salts of rosin acid, and the like, and these may be used alone or in mixture of two or more thereof.

As the molecular weight regulator, tertiary dodecyl mercaptan is mainly used, and as polymerization initiator, peroxides such as cumene hydroperoxide, diisopropylbenzenehydro peroxide, persulfate, sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, Oxidation-reduction catalyst systems made of a mixture with a reducing agent such as ferrous sulfate, dextrose, sodium pyrolate, sodium sulfite and the like can be used.

The polymerization conversion rate of the latex obtained after the completion of the polymerization was 96% or more, and an antioxidant and a stabilizer were administered to the latex to coagulate with an aqueous sulfuric acid solution at a temperature of 80 ° C. or higher, followed by dehydration and drying to obtain a powder. Stability of the graft copolymer latex prepared above is determined by measuring the solidified solid content (%) as shown in Equation 1 below.

[Equation 1]

When the solidified solid content is 0.7% or more, latex stability is extremely low and a large amount of coagulated material makes it difficult to obtain a graft polymer suitable for the present invention.

In addition, the graft ratio of the graft polymer is measured as follows. The graft polymer latex is coagulated, washed, and dried to obtain a powder form, 2 g of this powder is placed in 300 ml of acetone and stirred for 24 hours. The solution is separated using an ultracentrifuge, and then the separated acetone solution is dropped in methanol to obtain an ungrafted portion, which is dried and weighed. From these weights, the graft ratio is calculated according to the following equation.

[Equation 2]

The graft rate of the graft ABS polymer used in the present invention is preferably 26% or more. If the graft ratio is less than 26%, the thermal stability is lowered, which is not preferable.

The graft ABS polymer is used in an amount of 20 to 40 parts by weight, preferably 25 to 30 parts by weight, based on the thermoplastic resin composition of the present invention. It should be used in the above range can maintain the physical properties of the resin composition good.

b) heat resistant copolymer

The heat resistant copolymer is prepared by adjusting 50 to 80 parts by weight of α-methylstyrene (AMS) monomer and 20 to 50 parts by weight of acrylonitrile (AN) monomer in an appropriate ratio to copolymerize. As polymerization method, block polymerization is preferable. 26 to 30 parts by weight of toluene is used as the solvent and 0.1 to 1.0 parts by weight of di-t-dodecyl mercaptan is used as the solvent for 100 parts by weight of monomer.

The mixed solution of these reactants is charged in an average reaction time of 2 hours to 4 hours, and the reaction temperature is maintained at 140 ° C to 170 ° C.

The manufacturing process is a continuous process consisting of raw material input pump, continuous stirring tank, preheating tank and volatilization tank, polymer transfer pump and extrusion machine.

The molecular chain structure distribution of the obtained α-methylstyrene and acrylonitrile copolymer was analyzed using a ¹³ C NMR analyzer. The analytical method was obtained by dissolving the obtained pellets in deuterated chloroform and using tetramethylsilane as an internal standard, and the peaks appearing in the range of 141 to 144 ppm among the measured 140 to 150 ppm peaks were determined by the {AMS-AN-AN} chain structure. The area of these peaks was measured by taking the peaks in the range of 144.5 to 147 ppm as the {AMS-AMS-AN} chain structure and the peaks in the range of 147.5 to 150 ppm as the {AMS-AMS-AMS} chain structure. Analyzed.

In the present invention, the [AMS-AMS-AMS] chain structure in the molecular chain structure of the copolymer is preferably 14% or less. If it exceeds 14%, thermal stability will be degraded due to thermal decomposition of the [AMS-AMS-AMS] chain structure during processing. In addition, the chain structure of [AMS-AN-AN] is preferably 39% or less. If the [AMS-AN-AN] chain structure exceeds 39%, the heat resistance is poor.

The heat resistant copolymer is used in an amount of 60 to 80 parts by weight, preferably 70 to 75 parts by weight based on the thermoplastic resin composition of the present invention. The heat resistance of the resin composition can be maintained well in the above range.

c) low molecular weight acrylic additives

The acrylic additive used in the present invention is a low molecular weight acrylic resin. Styrene / acrylic resins having a molecular weight between 1000 and 20,000 may be preferably used, and the shape is not limited to the liquid state or the flake state. Specific examples of such acrylic additives include Toagosei Co. of Japan. Ltd. UP1000 (molecular weight: 1000) or UH2900 (molecular weight: 16,000) and UC3900 (molecular weight: 4,600).

The low molecular weight acrylic additive is used in the thermoplastic resin composition of the present invention in an amount of 1 to 10 parts by weight, preferably 1 to 3 parts by weight. To be used in the above range can be improved the heat adhesion of the resin composition.

The thermoplastic resin composition of the present invention may be prepared by mixing a graft ABS polymer, a heat resistant copolymer, and a low molecular weight acrylic additive. The thermoplastic resin composition may further include a lubricant or an antioxidant.

The use of polyethylene wax, magnesium stearate or mixtures thereof oxidized with the lubricant can further improve the thermal adhesion of the thermoplastic resin composition. The amount of the lubricant is 0.1 to 5 parts by weight, preferably 0.1 to 2 parts by weight.

The present invention will be described in more detail with reference to the following examples and comparative examples. However, an Example is for illustrating this invention and is not limited only to these.

EXAMPLE

Preparation Example 1 Preparation of Graft ABS Polymer

Manufacturing Process of Small Diameter Rubber Latex

In a nitrogen-substituted polymerization reactor (autoclave) 100 parts by weight of ion-exchanged water, 100 parts by weight of 1,3-butadiene as monomer, 1.2 parts by weight of potassium rosin salt as emulsifier, 1.5 parts by weight of potassium oleate salt, sodium carbonate as electrolyte ₂ CO ₃ ) 0.1 parts by weight, 0.5 parts by weight of potassium hydrogen carbonate (KHCO ₃ ), 0.3 parts by weight of tertiary dodecyl mercaptan (TDDM) as a molecular weight regulator, and the reaction temperature was raised to 55 ℃, persulfate as an initiator 0.3 parts by weight of potassium was administered in a batch to initiate the reaction. After reacting for 10 hours, 0.05 parts by weight of tertiary dodecyl mercaptan was further administered again, and reacted at 65 ° C. for 8 hours to terminate the reaction, thereby preparing small-diameter rubber latex.

The gel content of the prepared small-diameter rubber latex was 90%, the swelling index was 18, and the particle size was about 1000Å.

The gel content, swelling index, and particle size of the small-diameter rubber latex were measured by the following method.

(Gel content and swelling index)

The rubber latex was coagulated with dilute acid or metal salt and washed, dried in a vacuum oven at 60 ° C. for 24 hours, and the resulting rubber mass was chopped with scissors, and then 1 g of the rubber piece was placed in 100 g of toluene for 48 hours. After storage in a dark room at room temperature, the sol and the gel were separated and the gel content and the swelling index were measured according to the following equations (3) and (4).

[Equation 3]

[Equation 4]

The particle diameter was measured using a Nicomp 370 HPL (manufactured by Nicomp, USA) by the dynamic laser light skating method.

<Manufacture of large diameter rubber latex (fusion of small diameter rubber latex)>

100 parts by weight of the small-diameter rubber latex prepared above was added to the reactor, the stirring speed was adjusted to 10 rpm, and the temperature was adjusted to 30 ° C., and then 3.0 parts by weight of 7% acetic acid aqueous solution was gradually added for 1 hour, and then the stirring was stopped. A large diameter conjugated diene rubber latex was prepared by fusing a small diameter rubber latex by leaving it for 30 minutes. The large-diameter rubber latex prepared by the fusion process was analyzed in the same manner as the small-diameter rubber latex.

The rubber latex obtained at this time had a particle diameter of 3100 mm 3, a gel content of 90% and a swelling index of 17.

<Graft process (production of graft ABS copolymer)>

60 parts by weight of the large-diameter rubber latex prepared by the fusion method in the nitrogen-substituted polymerization reactor, 65 parts by weight of ion-exchanged water, 0.35 parts by weight of potassium rosinate emulsifier, 0.1 parts by weight of sodium ethylenediaminetetraacetate, 0.005 parts by weight of ferrous sulfate , 0.23 parts by weight of formaldehyde sodium sulfoxylate was administered to a batch reactor, and the temperature was raised to 70 ° C. In addition, 40 parts by weight of ion-exchanged water, 0.5 parts by weight of potassium rosinate, 19.2 parts by weight of styrene, 8.2 parts by weight of acrylonitrile, 0.3 parts by weight of T-dodecyl mercaptan, and 0.3 parts by weight of diisopropylene hydroperoxide were mixed. After continuous addition for 10 hours, 10 parts by weight of ion-exchanged water, 0.1 parts by weight of potassium rosinate, 9.6 parts by weight of styrene, 3.0 parts by weight of acrylonitrile, 0.1 parts by weight of T-dodecyl mercaptan, and diisopropylene hydride 0.1 parts by weight of the mixed emulsion of loperoxide was continuously added for 1 hour, and then heated to 80 ° C, and aged for 1 hour to terminate the reaction.

At this time, the polymerization conversion rate was 97.5% by weight, solid coagulation content was 0.2%, graft rate was 37%.

The latex was coagulated with an aqueous sulfuric acid solution, washed and a powder was obtained.

Preparation Example 2 Preparation of Heat Resistant Copolymer

70 parts by weight of α-methylstyrene, 30 parts by weight of acrylonitrile, 30 parts by weight of toluene with a solvent, and 0.15 parts by weight of di-t-dodecylmercaptan with a molecular weight modifier were added to the reactor continuously so that the average reaction time was 3 hours. The reaction temperature was maintained at 148 ° C. The polymerization liquid discharged from the reactor was heated in a preheating tank, volatilized unreacted monomer in a volatilization tank, and the temperature of the polymer was maintained at 210 ° C., and the SAN-based copolymer resin was processed into pellets using a polymer transfer pump extruder. .

Example 1

27 parts by weight of the graft ABS copolymer prepared according to Preparation Example 1, 73 parts by weight of the SAN copolymer prepared by the method of Preparation Example 2, 3 parts by weight of UP1000 (molecular weight 1,000, Toagosei of Japan) as a low molecular weight acrylic additive , 1 part by weight of EBA (ethylene bis stearamide) and 0.3 part by weight of antioxidant were mixed with a lubricant to prepare pellets at 230 ° C. using a twin screw extruder.

Example 2

A pellet was prepared in the same manner as in Example 1 except that UH2900 (molecular weight 16,000, Toagosei, Japan) was used as the low molecular weight acrylic additive.

Example 3

A pellet was prepared in the same manner as in Example 1 except that UC3900 (molecular weight 4,600, Toagosei, Japan) was used as the low molecular weight acrylic additive.

Example 4

Pellets were prepared in the same manner as in Example 1 except that UH2900 (molecular weight 16,000, Toagosei, Japan) was used as the low molecular weight acrylic additive.

Example 5

Pellets were prepared in the same manner as in Example 1, except that oxidized polyethylene wax was used instead of EBA as a lubricant.

Comparative Example 1

Pellets were prepared in the same manner as in Example 1, except that the low molecular weight acrylic additive was not used.

The pellets prepared according to Examples 1 to 5 and Comparative Example 1 were again injected to measure physical properties such as impact strength, tensile strength, flowability, and heat deformation temperature, and the results are shown in Table 1 below.

In addition, after the injection specimen was melted for 60 seconds at a pressure of 5 bar at 320 ° C., the weld strength between the resin and the metal surface was evaluated. That is, the degree of heat weldability was evaluated by the size and thickness of the strand generated after the resin contacted with the metal surface. Under the same thermal welding conditions, if the strands were thick and large, the heat welding strength was lowered. If the strands were not thin, the thermal welding strength was judged to be good. When all strands were generated as 0% and the state without strands as 100% was evaluated relatively according to the number and thickness of the strands.

division Tensile Strength ¹⁾ (kg / ㎠) Fluidity ²⁾ (g / 10min) Heat Deflection Temperature (1/4 ", ℃) ³⁾ Flexural Strength ⁴⁾ (kg / ㎠) Relative welding strength (%) Example 1 510 14.4 94.0 830 60 Example 2 520 12.3 96.8 850 50 Example 3 480 13.2 95.4 800 40 Example 4 490 16.8 91.0 810 40 Example 5 500 9.5 97.0 850 40 Comparative Example 1 510 9.9 97.5 850 30

Note: 1) Tensile strength: measured according to ASTM D638.

2) Flowability: measured according to ASTM D1238.

3) Heat Deflection Temperature (HDT): Measured according to ASTM D648.

4) Flexural Strength: Measured according to ASTM D790.

As shown in Table 1, it can be seen that the thermoplastic resin composition of the present invention has 10 to 30% improvement in thermal weldability without significantly lowering physical properties such as tensile strength.

The thermoplastic resin of the present invention is excellent in post-processing properties, in particular heat welding property, and excellent in adhesiveness and adhesive strength with other plastics and also excellent in releasability with metals. In addition, other physical properties such as impact resistance are not lowered.

Claims (5)

a) graft ABS polymer; b) heat resistant copolymers; And c) a low molecular weight acrylic additive. The method of claim 1, The graft ABS polymer is 20 to 40 parts by weight, 60 to 80 parts by weight of the heat-resistant copolymer, and 1 to 5 parts by weight of the low molecular weight acrylic additive. The method of claim 1, The graft ABS polymer is prepared by graft reacting an aromatic vinyl compound and a vinyl cyanide compound to a conjugated diene rubber latex. The method of claim 1, The heat resistant copolymer is a thermoplastic resin composition of a copolymer of α-methylstyrene (AMS) and acrylonitrile (AN). The method of claim 1, The molecular weight of the low molecular weight acrylic additive is a thermoplastic resin composition of 1,000 to 20,000 acrylic resin.