KR20010056218A - Thermoplastic Resin Composition with Good Antibacterial Characteristics - Google Patents

Abstract

PURPOSE: Provided is a thermoplastic styrene resin composition which can be used for various products requiring antibiosis due to its excellent antibiosis and anti-fungus effects and preserves existing ABS(acrylonitrile-butadiene styrene copolymer) character without deterioration of general physical properties and heat stability. CONSTITUTION: A thermoplastic resin composition with excellent antibiosis comprises (i) a basic resin 100wt.% composed of graft rubber polymer 30-50wt.% containing diene based rubber 40-60 wt.%, SAN resin 70-50wt.% of molecular weight 90,000-120,000 copolymerized of aromatic vinyl monomer and unsaturated nitrile monomer; (ii) inorganic antibiotics 0.5-1.0wt.%; and (iii) organic antibiotics 0.5-0.1wt.%.

Description

Thermoplastic Resin Composition with Good Antibacterial Characteristics

Field of invention

The present invention relates to an acrylonitrile-butadiene-styrene resin (hereinafter ABS resin) composition having excellent antibacterial properties. More specifically, the present invention relates to a styrene resin composition having an excellent antimicrobial property without selecting the organic antimicrobial agent and inorganic antimicrobial agent, and by adjusting the combination ratio to reduce the physical properties of the ABS resin and discoloration phenomenon.

Background of the Invention

Generally, the acrylonitrile-butadiene-styrene copolymer (hereinafter referred to as ABS resin) obtained by graft copolymerization of an aromatic vinyl monomer represented by styrene and an unsaturated nitrile monomer represented by acrylonitrile to a butadiene-based rubbery polymer is referred to as impact resistance and processability. It is excellent in mechanical strength. Therefore, ABS resin is applied to the fields of electricity, electronics, OA equipment, automobiles, sundries, building materials, and the like. That is, in the electrical and electronic fields of the housing and parts of household appliances including air conditioners, vacuum cleaners, washing machines, etc., in the field of OA equipment of facsimile, computers, and telephone housings, and for automotive parts and toys using heat, plating, and matte ABS. , Leisure products, and upholstery.

In recent years, the product development which strengthened the function according to each use is progressing actively, and the high functional ABS resin which strengthened weather resistance, flame retardancy, transparency, antibacterial property, etc. is commercialized.

In general, plastics are thought to be difficult to deteriorate to microorganisms, but additives used in processing become nutrients to microorganisms, and contaminants attached to the surface of plastics become nutrients to microorganisms and thus may be degraded. In addition, due to the generalization of plastics, the encapsulation of residential environments, and the optimization of room temperature, products that have antibacterial properties have been developed in the plastics sector in response to the reality that an environment that matches the growth conditions of microorganisms has been developed. It is increasing. In particular, in recent years, interest in hygiene has increased, and various methods have been applied to plastics in order to prevent contamination by bacteria. In general, a method of giving antimicrobial properties to plastics is a method of using an antimicrobial agent. The antimicrobial properties vary depending on the type and the amount of the antimicrobial agent and whether the product is deteriorated.

Antimicrobial agents conventionally used to impart antimicrobial properties to plastics can be largely divided into inorganic and organic antimicrobial agents. The inorganic antimicrobial agent has the advantage of having a continuous antimicrobial effect because it is not easily eluted, but requires a large amount of use, and there is a problem of inducing resin discoloration by causing decomposition of metal ions during processing as the amount is increased. On the other hand, the organic antimicrobial agent is excellent in antimicrobial effect, but because it is easily eluted, it was difficult to obtain a continuous antimicrobial effect.

Therefore, when using an inorganic antimicrobial agent or an organic antimicrobial agent alone, the conventional problem is not overcome. That is, when the inorganic antimicrobial agent is used alone, the amount of the antimicrobial agent should be increased to secure the antimicrobial properties. The increased antimicrobial component causes discoloration of the resin and a decrease in physical properties, resulting in an increase in manufacturing cost. In addition, when the organic antimicrobial agent is used alone, the antimicrobial persistence is lowered due to elution, resulting in a decrease in the antimicrobial properties of the entire resin.

Therefore, the present inventors overcome the problems that occur when using the conventional antimicrobial agent, by using a combination of appropriately selected types of inorganic antimicrobial and organic antimicrobial agents in a way that can maintain the antimicrobial properties, by adjusting the amount of ABS resin ABS resin has excellent antibacterial properties without physical property degradation and discoloration.

An object of the present invention is to provide a composition of ABS resin excellent in antibacterial properties while maintaining the properties of the ABS product.

Another object of the present invention is to add a combination of inorganic antimicrobial and organic antimicrobial agent in a specific ratio to the ABS resin, but to provide a ABS resin excellent in antibacterial properties more simply by manufacturing in a conventional processing method.

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 thermoplastic resin composition is excellent in antibacterial properties as produced according to the invention (A) (a ₁₎ a diene rubber content of 40 to 60% by weight of the graft rubber polymer and 30 to 50% by weight of (a ₂₎ an aromatic vinyl monomer And 100 weight part of base resin which consists of 70-50 weight% of SAN resin which the weight average molecular weight which copolymerized unsaturated nitrile-type monomer is 90,000-120,000; (B) 0.5 to 1.0 parts by weight of the inorganic antibacterial agent; And (C) 0.5 to 0.1 parts by weight of an organic antimicrobial agent, and prepared by melt kneading. At this time, the inorganic antimicrobial agent is selected from the group consisting of antimicrobial zeolite, antimicrobial apatite, and zinc lipion, and the organic antimicrobial agent is zizolyl benzimidazole, normal chlorophenyl by guanido hexanedi gluconate , Polyhexylmethylene guanidine phosphite, and dehydro sodium acetate. In particular, the ratio of use of the organic antimicrobial agent and the inorganic antimicrobial agent is 1: 1 to 1:10, and the total amount of the organic antimicrobial agent and the inorganic antimicrobial agent is used in the range of 0.5 to 1 part by weight based on 100 parts by weight of the basic resin.

If the graft rubber copolymer is used in an amount of 30 wt% or less, the impact strength of the ABS resin may be lowered. If the graft rubber copolymer is used in an amount of 50 wt% or more, the rubber properties may increase, resulting in a decrease in flow characteristics and an increase in manufacturing cost. . If the weight average molecular weight of the SAN resin is 90,000 or less, the flow characteristics are improved while the impact strength is sharply lowered, and if it is 120,000 or more, the impact strength is increased while the flow characteristics are lowered. In addition, if the amount of the inorganic antimicrobial agent is 0.5 parts by weight or less, the continuous antimicrobial properties are lowered, and when used more than 1.0 parts by weight, discoloration problems may occur due to an increase in the metal ion content of the inorganic antimicrobial agent. If the amount of the organic antimicrobial agent is less than 0.1 part by weight, the amount of remaining antimicrobial agent is reduced by eluting and the amount of the remaining antimicrobial agent is decreased. If the amount of the organic antimicrobial agent is used more than 0.5 part by weight, deterioration of the organic antimicrobial agent occurs during processing. There arises a problem that is caused and the manufacturing cost rises. When the ratio of organic antimicrobials and inorganic antimicrobials decreases, the ratio of inorganic antimicrobials decreases, while the ratio of organic and inorganic antimicrobials decreases. As a result, the characteristics of the organic antimicrobial agent are reduced, thereby reducing the complementary antimicrobial properties between the organic antimicrobial agent and the inorganic antimicrobial agent. In addition, if the total amount of the antimicrobial agent to be used is 0.5 parts by weight or less, the antimicrobial effect by using the antimicrobial agent is lowered, if more than 1.0 parts by weight, the antibacterial effect is excellent, but there is a problem that causes discoloration of the ABS resin and the manufacturing cost increases.

The resin composition of the present invention can be more clearly understood by the following examples, the following examples are merely illustrative purposes of the present invention and are not intended to limit the scope of the invention.

Example 1

30 parts by weight of graft copolymer having 50% by weight of butadiene rubber and 70 parts by weight of a SAN resin having a good weight average molecular weight of 120,000. 0.5 parts by weight of polyhexylmethylene guanidine phosphite was mixed and melt-extruded to prepare pellets, and the prepared pellets were injection molded by an injection molding machine to prepare test specimens.

Examples 2-5

Except for changing the content of the ABS resin and SAN resin, the inorganic antimicrobial agent, and the organic antimicrobial content of the basic resin used as shown in Table 1, the test specimens were prepared in the same manner as in Example 1 to measure the physical properties.

Comparative Examples 1 to 6

The test specimens were prepared in the same manner as in Example 1 except that the contents of the ABS resin and the SAN resin, the inorganic antimicrobial agent, and the organic antimicrobial agent were used alone or in small or excessive amounts as shown in Table 1. Physical properties were measured.

Basic resin content (%) Antibacterial content (parts by weight) Graft copolymer SAN Inorganic antibacterial agents Organic antimicrobial agents Example 1 30 70 0.5 0.5 Example 2 30 70 0.9 0.1 Example 3 40 60 0.5 0.25 Example 4 50 50 0.8 0.2 Example 5 50 50 0.25 0.25 Comparative Example 1 30 70 1.0 - Comparative Example 2 30 70 - 0.5 Comparative Example 3 30 70 0.3 0.1 Comparative Example 4 30 70 0.1 0.3 Comparative Example 5 40 60 0.5 - Comparative Example 6 50 50 1.0 0.5

The physical properties of the specimens prepared in Examples 1 to 5 and Comparative Examples 1 to 6 were measured, and the results are shown in Table 2.

Notched Izod impact strength (kg · cm / cm) on the specimen was measured according to ASTM D251 with a thickness of 6.4 mm.

Evaluation for flowability (220 ° C., 10 kg, 10 g / min) was measured using ASTM D1238.

Thermal stability was measured using Cheil Industries Simple Method. In other words, the resin processed into pellets is injected into a hopper of 100 tons of mold force, and one molded article is molded while the cylinder temperature is maintained at 250 ° C. Compare the degree of color change between the initial unsettled molded product and the second 20-minute stay molded specimen and mark it as △ E. In other words, if the difference of △ E is small, the discoloration is low, and the thermal stability of the product is excellent, and it is widely used as a comparative comparative evaluation method.In general, if △ E is less than 1.0, it is a very good level, and if △ E is 2 or more, the product heat Stability problems are expected. At this time, the color measurement (ΔE) was measured according to ASTM D1925.

Antimicrobial properties were evaluated by the following method.

(1) Measurement standard: Press-contact method was applied, and used strains were E. coli (ESCHERICHIA COLI ATCC 25922), Bacillus subtilis (BACILLYS MEGATERIUM ATCC 10778), Pseudomonas aeruginosa (PSEUDOMONAS AERUGINOSA ATCC 15442), Typhoid bacteria (SALONELLA TYPHIMYRIYM), etc. KCTC Four or more kinds were used.

The evaluation method of the antimicrobial properties is carried out by the following procedure, and when the bacterial decay rate is 90% or more, the antimicrobial effect is evaluated.

(2) Method for measuring antimicrobial properties: After inoculating test specimens and control specimens with the test specimen, extract the cultured bacteria after closely contacting a certain amount of the inoculum between the specimen and the specimen. When the number of bacteria present in the extract is measured, the rate of bacterial reduction between the antimicrobial test specimen and the control specimen is measured. The size of the test piece shall be rectangular with 5cm x 6cm in width and length, respectively. In addition, the control piece is also manufactured to the same size as the test specimen.

Inoculum preparation is appropriately diluted with the broth broth cultured for 24 hours so that the number of bacteria regenerated from the test specimen or control at contact time "0" time is 1 to 2 x 10 ⁶ , and 0.1 ml of the bacterial solution is used as the inoculum. At this time, the dilution of the culture solution using physiological saline.

The control specimen is the same kind and structure as the test specimen, but is used as a control means for test specimens inoculated with bacteria and non-inoculation specimens.

Inoculation of test specimens and control specimens is shaken for 24 hours when using E. coli and allowed to stand for 15 minutes before preparing the inoculum. Using a pipette, 0.1 ml of inoculum is evenly adhered on the test piece and the control piece. Sampling at contact time "0" is carried out as soon as possible after inoculation, inoculated in a pipette dish and washed with neutralizing solution phosphate buffer (pH 7.2). Also, uninoculated specimens are placed in a pipette dish and washed with a neutralizing solution (20 ml). Shake slowly for exactly 1 minute, then dilute continuously. 0.2 ml of each of them is harvested and inoculated thinly on a flat medium of Tryptone glucose extract agar medium. The dilution of 10 times, 10 ² times is usually suitable. The neutralizing solution should be neutralized by special antibacterial treatment and be suitable for the required pH conditions. Sampling from the culture through constant contact time is inoculated test pieces and inoculated control pieces are placed in a sterile sterile plastic container and allowed to stand at 25 ℃ for 24 hours at 1kg / cm² pressure. After incubation, the specimen and the control piece are placed in a pipette dish, washed with neutralizing solution, shaken slowly for exactly 1 minute, and then diluted continuously. Incubate in a plate incubator at 30 ° C. for 48 hours.

Antifungal properties were evaluated as follows.

(1) Measurement standard: ASTN G-21 method is applied and used strains are ASPEGILLUS NIDGER ATCC9642, PENICILLIUM PINOPHILUM ATCC 11797, CHAETOMIUM GLOBOSUM ATCC 6205, GILOCLADIUM VIRENS ATCC 9645, AUREIBASIDIUM PULLKULANS ATCC 15233. The degree of growth of the fungus is evaluated according to the grading criteria set as follows after incubating the test specimens for 3 weeks, and in the case of 0 grade, the antifungal effect is evaluated.

Grade 0: No mold growth

Grade 1: Grow up to 25% of the specimen area

Grade 2: 25 to 50% of the specimen area

Grade 3: grow to 50-75% of specimen area

Grade 4: Over 75% of specimen area

(2) Measuring method: Inoculate test specimen and control specimen with mixed spore suspension and incubate for a certain period of time, then compare the growth status between the antifungal test specimen and the control specimen through the growth status of the cultured mold. It is a qualitative indication of the degree of antifungal activity. The size of the test piece is prepared by 50 × 50 mm to prepare three pieces, and the control piece is also prepared in the same way. For inoculum preparation, 50 ml of sterile water added with 0.005% of dioctyl sodium sulfosuccinate was placed in a 100 ml Erlenmeyer flask, and each mold spores were collected and sufficiently dispersed. Filter the contents with gauze to make the filtrate a mixed spore suspension. For the preparation of test and control pieces, place the specimens on the medium prepared in a 90 mm x 90 mm glass container. The size of the test specimen and the reference specimen into the container shall be prepared 50mm × 50mm, and three containers for the specimen and the reference specimen shall be prepared.

The medium used is Kg ₂ PO ₄ 0.7g, K ₂ HPO ₄ 0.7g, MgSOP ₄ · 7H ₂ O 0.7g, NH ₄ NO ₃ 1.0g, NaC1 0.005g, FeSO ₄ · 7H ₂ O 0.002g, ZnSO ₄ · 7H Accurately weigh 0.001 g of ₂ O and 15.0 g of Agar, place in a container, heat, dissolve well, and adjust the pH to 6.8 with sodium hydroxide. It is sterilized for 20 minutes at a steam pressure of 1,055 g / cm² and 120 ± 2 ° C in a autoclave. The control piece is used as a control means for the control and non-inoculated test pieces inoculated with the fungus.

Inoculation of test specimens and control specimens should be prepared in advance the day before the use of the mixed spores and sprayed on the sample with a sterilized sprayer on the day of the test. Cultivation of test pieces and control pieces is incubated in a plate incubator for 3 weeks at 28 ° C. and 85% humidity.

Physical property evaluation results of Examples and Comparative Examples General property evaluation Injection Stability Evaluation Antimicrobial Evaluation IZOD MI △ E % Decay Mold Growth Grade Example 1 20 30 0.8 95 0 Example 2 20 30 0.8 95 0 Example 3 30 20 0.9 95 0 Example 4 30 20 0.9 95 0 Example 5 40 10 1.0 95 0 Comparative Example 1 20 30 0.8 50 0 Comparative Example 2 20 30 0.8 96 3 Comparative Example 3 20 30 0.8 50 3 Comparative Example 4 20 30 0.8 50 0 Comparative Example 5 30 20 0.9 50 0 Comparative Example 6 40 10 3.0 95 0

From Table 2, it can be seen that Examples 1 to 5 reached satisfactory levels of impact strength, fluidity, and heat resistance even though the organic and inorganic antimicrobial agents were added. In particular, due to the complementary action of the inorganic and organic antimicrobial agents used in a certain range, the decay rate was all 95% or more, and no growth phenomenon of the fungus was observed.

On the other hand, Comparative Examples 2, 3 and 4, in which the inorganic antimicrobial agent was used alone or under-used, the decay rate or the antifungal properties were lowered due to the continuous degradation of the antimicrobial properties, and Comparative Examples 1 and 5 in which the organic antimicrobial agent was not used. It can be seen that the decay rate is quite low. In particular, Comparative Example 6 in which the total amount of the antimicrobial agent exceeds 1 part by weight, while the antimicrobial activity was maintained, the thermal stability was sharply lowered.

Styrene-based resin composition excellent in the antimicrobial properties of the present invention is excellent in antibacterial and antifungal properties can be used in a variety of products that require antimicrobial properties and has the advantage of maintaining the existing ABS properties without deteriorating general physical properties and thermal stability have.

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 (3)

(A) 30 to 50% by weight of the graft rubber polymer having (a ₁ ) diene rubber content of 40 to 60% by weight and (a ₂ ) the weight average molecular weight of copolymerized aromatic vinyl monomer and unsaturated nitrile monomer is 90,000 to 100 parts by weight of a base resin composed of 70 to 50% by weight of a SAN resin of 120,000; (B) 0.5 to 1.0 parts by weight of the inorganic antibacterial agent; And (C) 0.5 to 0.1 parts by weight of the organic antibacterial agent; The thermoplastic resin composition excellent in the antimicrobial characteristic characterized by consisting of. The method of claim 1, wherein the inorganic antimicrobial agent is at least one selected from the group consisting of antimicrobial zeolite, antimicrobial apatite, and zinc lipion, and the organic antimicrobial agent is zizolyl benzimidazole, normal chlorophenyl by guanido hexanedi A thermoplastic resin composition having excellent antibacterial properties, characterized in that at least one member is selected from the group consisting of gluconate, polyhexylmethylene guanidine phosphite, and dehydro sodium acetate. The method according to claim 1, wherein the organic antimicrobial agent and the inorganic antimicrobial agent are used in a ratio of 1: 1 to 1:10, and the total amount of the organic antimicrobial agent and the inorganic antimicrobial agent is 0.5 to 1 part by weight based on 100 parts by weight of the base resin. A thermoplastic resin composition having excellent antibacterial properties.