KR100727231B1 - Thermoplastic resin composition with good antibacterial characteristics and method for preparing the same - Google Patents

Abstract

 The present invention relates to a thermoplastic resin composition and a method for preparing the same, and more particularly, to a thermoplastic resin composition comprising 1 to 25 parts by weight of an inorganic antimicrobial dispersion based on 100 parts by weight of an organic latex. By introducing the inorganic antimicrobial component into the dispersion to effectively induce dispersion of the inorganic antimicrobial agent, there is an effect of providing a thermoplastic resin composition having the effect of improving the antimicrobial properties without mechanical property degradation and discoloration phenomenon.

Thermoplastic, Antimicrobial, Latex, Inorganic Antibacterial

Description

Thermoplastic resin composition excellent in antimicrobial properties and its manufacturing method {THERMOPLASTIC RESIN COMPOSITION WITH GOOD ANTIBACTERIAL CHARACTERISTICS AND METHOD FOR PREPARING THE SAME}

The present invention relates to a thermoplastic resin composition and a method for preparing the same, and more particularly, by introducing an inorganic antimicrobial agent into a dispersion in an organic latex, inducing effective dispersion of the antimicrobial agent, thereby improving the antimicrobial properties without deteriorating mechanical properties and discoloration. A thermoplastic resin composition and a method for producing the same.

Plastics are generally considered to be difficult to deteriorate with microorganisms, but when additives used in processing become nutrients to microorganisms and contaminants attached to plastic surfaces become nutrients to microorganisms, they are often degraded by microorganisms. have.

In addition, due to the generalization of plastics, the encapsulation of residential environments, and the optimization of room temperature, products that have antimicrobial properties have been developed in the plastics sector in response to the reality that an environment that matches microbial growth conditions is being developed. It is increasing. In particular, in recent years, interest in hygiene has increased, and various methods have been applied to plastics to prevent contamination by bacteria.

As a method for imparting antimicrobial properties to plastics, there are kneading methods in which drugs are added during molding processing, and post-treatment methods for surface processing after molding, and kneading methods take up most of them.

Antimicrobials used to impart antimicrobial properties to plastics can be broadly classified into organic and inorganic antimicrobials. Organic antimicrobials are primarily in liquid form and are added to products that require antimicrobial activity in a short time. Organic antibiotics temporarily have higher antimicrobial activity than inorganic antimicrobials, but their antimicrobial activity persists very short. In addition, there is a problem in human safety because of the high acute toxicity with the fear of generating resistant bacteria. Due to these problems, the area of use of organic antimicrobials has been reduced.

Inorganic antimicrobials are products made by substituting silver, zinc and copper, which are metal ions that have antibacterial effects on inorganic substances such as zeolite, calcium phosphate, zirconium phosphate, and silica gel, and are currently used in various fields such as plastic products, paper, and textiles. It is becoming. Inorganic antimicrobials have a temporary antimicrobial activity lower than that of organic antimicrobials, but have high human safety, no resistant bacteria, and antimicrobial duration is almost semi-permanent. However, in order to obtain antimicrobial activity, a relatively large amount of use is required, and as the amount of use increases, there is a problem of inducing discoloration of the resin due to decomposition of metal ions during processing. That is, when using an inorganic antimicrobial agent, the amount of antimicrobial agent should be increased in order to secure antimicrobial properties. The increased antimicrobial component causes discoloration of the resin and deterioration of physical properties, resulting in an increase in manufacturing cost.

In order to solve the problems of the prior art as described above, the present invention is to introduce an inorganic antimicrobial agent into the organic latex as a dispersion, inducing the effective dispersion of the antimicrobial agent to improve the antimicrobial properties without mechanical properties degradation and discoloration phenomenon It aims to provide.

Moreover, an object of this invention is to provide the manufacturing method of the said thermoplastic resin composition.

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

In order to achieve the above object, the present invention provides a thermoplastic resin composition comprising 1 to 25 parts by weight of the inorganic antimicrobial dispersion based on 100 parts by weight of the organic latex.

In addition, the present invention

Preparing an organic latex;

Preparing a mixed solution by blending an inorganic antimicrobial dispersion in the organic latex; And

Preparing the mixed solution into powder by agglomeration / drying or spray drying;

Method (A) comprising, or

Preparing an organic latex; And

Preparing an inorganic antimicrobial dispersion in a powder range of -20 to 0 ° C. in the glass transition temperature range of the organic latex and then drying the organic latex to prepare a powder;

It provides a method for producing a thermoplastic resin composition, characterized in that any one method selected from the method (B) comprising a.

Hereinafter, the present invention will be described in detail.

The present invention relates to a thermoplastic resin composition which effectively prevents mechanical property deterioration and discoloration and continuously secures antimicrobial properties by effectively introducing an inorganic antibacterial agent into a resin including an organic component, particularly a rubber component.

In addition, in the aggregation of the organic resin latex produced by the emulsion polymerization method with an acid or a salt, an inorganic antimicrobial agent is added at an appropriate time to form an organic material cell on the inorganic material core to an inorganic material cell or an organic material cell on the organic material core. By forming a hybrid form to form a primary dispersion of the inorganic material in the organic material and to make the secondary dispersion through the injection / injection process on the acrylonitrile copolymer resin prepared by solution polymerization to improve the dispersibility of the inorganic antimicrobial agent It relates to a method for producing a thermoplastic resin composition capable of improving the antimicrobial properties of the.

Preparation of Organic Latex

The organic latex is a single or two or more kinds of ABS (acrylonitrile-butadiene-styrene) resin, ASA (acrylonitrile-styrene-acrylate) resin, MBS (methyl methacrylate-butadiene-styrene) resin, etc. Can be used.

The organic latex has a particle size of 2500 to 3500Å, gel content of 65 to 95%, and swelling index of 10 to 50 parts by weight of polybutadiene rubber latex (A) and particle size and gel content of the same range, the swelling index 40 to 80 parts by weight of a polybutadiene mixture composed of 50 to 90 parts by weight of a polybutadiene rubber latex (B) having an amount of about 18 to 40, 20 to 80 parts by weight of two or more monomer mixtures composed of an aromatic vinyl compound or a vinyl cyan compound It is prepared by graft copolymerization by emulsion polymerization in a ratio of 40 to 60.

In the preparation of the organic latex, 0.1 to 2 parts by weight of an emulsifier, 0.2 to 1.0 parts by weight of a molecular weight regulator, and 0.05 to 1.0 parts by weight of a polymerization initiator may be used to induce emulsion polymerization stability and initiation reaction.

In the method for preparing the organic latex, 0 to 30% of the total monomers to be used are reacted by batch administration in the initial reaction, and at the same time, 0 to 70% of the monomer is used between 0 to 60 minutes, preferably 0 to 30 minutes, After continuously administering an emulsifier and an monomer in an emulsified state composed of an initiator, the reaction proceeds further for 1 hour and the reaction is completed.

The method of preparing the organic latex may be a method of dividing 100% of the total monomers to be used in addition to the production method in a batch or a continuous administration of the entire amount, and is not limited to a specific polymerization method. However, in order to achieve the high impact strength and effective polymerization stability of the ABS resin, it is preferable to divide the monomer in an appropriate range into a batch, and to continuously add the remaining portion in the emulsified state as described above.

The method for producing the organic latex is a reaction temperature of 40 to 80 ℃, the reaction time is preferably 2 to 7 hours, it can be changed depending on the polymerization initiator or required physical properties.

Preparation of Inorganic Antimicrobial Dispersion

The inorganic antimicrobial dispersion is prepared by adding an inorganic antimicrobial agent and an emulsifier and stirring using a homo mixer to disperse the organic latex and the inorganic antimicrobial agent.

The inorganic antibacterial agent is a product made by substituting silver, zinc, copper, etc., which are metal ions which have an antimicrobial action on inorganic substances such as zeolite, calcium phosphate, zirconium phosphate, silica gel, etc. It can be used individually or in mixture of 2 or more types.

The inorganic antimicrobial agent may include 1 to 5 parts by weight of an emulsifier based on 100 parts by weight of the inorganic antimicrobial agent.

The emulsifier may be a sulfonate-based emulsifier such as sodium lauryl sulfate, sodium dodecyl benzene sulfonate, or sodium alkyl benzene sulfonate.

It is preferable that the said emulsifier is pH 7 or less. When the pH is greater than 7, not only the dispersion stability of the inorganic antimicrobial particles is greatly lowered, but also the mechanical properties are degraded due to the phase separation phenomenon occurring during aggregation and the phase separation phenomenon during processing by introducing this into the organic latex. .

The inorganic antimicrobial dispersion may be prepared by adding an inorganic antimicrobial agent and an emulsifier and stirring for 1 hour at a stirring speed of 5,000 rpm or more using a homo mixer.

Introduction of Inorganic Antimicrobial Dispersions in Organic Latexes

The inorganic antimicrobial agent dispersion may be introduced into the organic latex by introducing an inorganic antimicrobial agent dispersion into the organic latex, followed by latex blending, and then coagulating with an acid or a salt and dehydrating and drying the powder. Method (A) and the like can be used.

The method (A) of obtaining the powder after blending the inorganic antimicrobial dispersion on a latex solution has a simple advantage in the manufacturing process, but should be blended with an organic latex, so an emulsifier suitable for blending should be selected when preparing the inorganic antimicrobial dispersion. do.

Another method of introducing the inorganic antimicrobial dispersion into the organic latex may include an inorganic antimicrobial dispersion immediately after the second agglomeration occurs in the glass transition temperature range of the organic latex when the organic latex is aggregated with an acid or a salt. Method (B) for preparing a powder by adding and drying can be used.

The temperature at which the inorganic antimicrobial dispersion is added is preferably in the temperature range of -20 to 0 ° C. of the glass transition temperature range of the organic latex.

Injecting the inorganic antimicrobial dispersion in the preparation method (B), and then further maintained for 30 to 40 minutes at a temperature in the range of 0 to +10 ℃ in the glass transition temperature range of the organic latex to form more solid particles Dehydration drying may yield an organic powder to which an inorganic antibacterial agent is added.

Method (B) of obtaining an inorganic antimicrobial dispersion after introducing an inorganic antimicrobial dispersion in a specific temperature range during aggregation of the organic latex can not only properly adjust the position of the inorganic antimicrobial agent according to the characteristics of the desired physical properties, but also improve the stability of the organic latex. There is an advantage in that the inorganic antimicrobial agent can be introduced in a range that does not significantly decrease.

The inorganic antimicrobial dispersion is preferably used in an amount of 1 to 25 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of the organic latex. If the content is less than 1 part by weight, there is no deterioration in mechanical properties when the inorganic antimicrobial dispersion is added. However, the content of the inorganic antimicrobial agent is too small to obtain a desired antimicrobial effect. When agglomeration, there is a problem that the temperature rise due to the formation of particles of the powder and the inorganic antimicrobial agent that is not included in the powder is excessively generated to lower the mechanical properties.

The flocculant used in the flocculation may be an acid flocculant such as sulfuric acid or acetic acid; Salt flocculants such as HgSO ₄ or CaCl ₂ ; Etc. can be used.

An antioxidant may be further included to minimize the risk of fire when the powder is manufactured.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

EXAMPLE

Example 1

Preparation of Inorganic Antimicrobial Dispersion

In a four-necked round flask equipped with a stirrer, 200 parts by weight of water and 2 parts by weight of sodium lauryl sulfate were added and stirred at 5,000 rpm using a homo mixer. Thus, 100 parts by weight of an inorganic antibacterial agent (antibacterial zeolite) was 40 ° C. Was slowly added to prepare an inorganic antimicrobial dispersion solution.

Preparation of Organic Latex

30 parts by weight of polybutadiene rubber latex having a gel content of 65%, a particle diameter of 3,000 Å and a swelling index of 20 in a nitrogen-substituted polymerization reactor, and a polybutadiene rubber latex having a gel content of 85% and a swelling index of 30. 90 parts by weight of ion-exchanged water, 0.5 parts by weight of potassium rosinate emulsifier, 18.5 parts by weight of styrene, 6.7 parts by weight of acrylonitrile, 0.3 parts by weight of tertiary dodecyl mercaptan, 0.05 parts by weight of sodium pyrophosphate, 0.06 part by weight of dextrose, 0.001 part by weight of ferrous sulfide, and 0.08 part by weight of tert-butyl hydroperoxide were collectively administered at 45 ° C., and the reaction was carried out while raising the reaction temperature to 70 ° C. over 60 minutes.

10 parts by weight of ion-exchanged water, 0.8 parts by weight of potassium rosinate, 15.8 parts by weight of styrene, 6.7 parts by weight of acrylonitrile, 0.05 parts by weight of sodium pyrophosphate, 0.06 parts by weight of dextrose, 0.001 parts by weight of ferrous sulfide, 0.1 part by weight of the mixed emulsion solution of cumene hydroperoxide was continuously administered for 60 minutes, then heated to 80 ° C. again, and aged for 1 hour, and the reaction was terminated. At this time, the polymerization conversion rate was 98.9%, the total solid content was 48.2%, the solid coagulation content was 0.02%.

Introduction of Inorganic Antimicrobial Agents in Organic Latexes

450 parts by weight of water and 1.5 parts by weight of sulfuric acid were previously added to a flocculation tank capable of rapid temperature increase to 100 ° C., and then the temperature was maintained at 84 ° C., and then 100 parts by weight of the organic latex (ABS latex) prepared above was continuously added.

After primary aggregation of the injected latex occurred, the temperature was raised to 90 ° C. over 10 minutes, and 5 parts by weight of the inorganic antimicrobial dispersion was added to the point where the latex viscosity rapidly increased. After the addition, the temperature was raised to 95 ° C., the temperature was stopped, and aged for 30 minutes. When aging was completed, the temperature was 92 ° C. After aging, the separation of the mother liquor from the sample was confirmed whether the inorganic antimicrobial dispersion was separated. After the completion of the reaction aging was dried to prepare a powder.

30 parts by weight of the obtained organic-based powder containing the inorganic antimicrobial agent and 100,000 parts by weight of a styrene-acrylonitrile (SAN) copolymer having a molecular weight of 100,000 and an acrylonitrile content of 27% were mixed and pressed / injected into a specimen. It was prepared, and physical properties and antimicrobial properties were measured.

Example 2

Except for using 10 parts by weight of the inorganic antimicrobial dispersion in Example 1 was carried out in the same manner as in Example 1.

Example 3

In the method of introducing the inorganic antimicrobial dispersion into the organic latex in Example 1, Example 1 except that the powder prepared by agglomeration and drying the inorganic antimicrobial dispersion in advance at room temperature after the latex blending was used It was carried out in the same manner as.

Example 4

An inorganic antimicrobial dispersion was introduced in Example 1 in the same manner as in Example 3, except that powder prepared using a spray drying method was used in the same manner as in Example 1. The temperature of the air introduced during spray drying was 170 ° C. and the air temperature at the outlet side was 90 ° C.

Comparative Example 1

Except for using the powder prepared in Example 1 without introducing the inorganic antimicrobial dispersion was carried out in the same manner as in Example 1.

Comparative Example 2

In Example 1, the powder was prepared in the same manner as in Comparative Example 1, except that 5 parts by weight of the same inorganic antimicrobial agent was extruded and extruded and extruded.

The physical properties of the specimens prepared according to the Examples and Comparative Examples were measured by the following method and the results are shown in Table 1 below.

* Izod impact strength test-measured according to ASTM D256 method. Specimen thickness is 1/4.

* Melt Flow Index (MI)-It measured according to ASTM D1238 method under the conditions of 220 degreeC and 10 Kg.

* Injection residence thermal stability-Molded one molded product by inserting resin processed into pellet form while maintaining the cylinder temperature of the injection machine at 250 ℃, and maintained it for 20 minutes in a stagnant state. The degree of color change between the stay molded product and the second 20 minute stay molded product is compared and expressed as ΔE. If the difference of △ E is small, the discoloration is excellent, 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. Stability problems are expected. At this time, the measurement of the degree of color change (ΔE) was measured according to ASTM D1925.

* Antibacterial (Attenuation Rate (%))

1) Measurement standard-Applying pressure-adhesive method, the used strains were Escherichia coli ATCC 25922, Bacillus Megaterium ATCC 10778, Pseudomonas Aeruginosa ATCC 15442, Salonella Typhimyriym KCTC 1925, etc. More than species were used.

2) Antimicrobial Measurement Method-After inoculating test specimen and control specimen with test specimen, extract the cultured bacteria after closely contacting a certain amount of inoculum between specimen and specimen. When the number of bacteria in the extract is measured, the rate of bacterial reduction between the antimicrobial and the control specimens is measured. The size of the test piece shall be rectangular, 5 cm x 6 cm in width and length, respectively, and N number shall be three pairs or more. In addition, the control piece is also prepared in the same size as the test piece.

Inoculum preparation is appropriately diluted with broth broth cultured for 24 hours so that the number of bacteria regenerated from the test or control pieces at 0 hour contact 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, with the inoculated controls in a pipette and washed with neutralizing solution phosphate buffer (pH 7.2). In addition, uninoculated test pieces are also 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 in a thin plate of Tryptone glucose extract cloth medium. At this time, 10-fold, 100-fold dilution is usually suitable. Neutralization solution should be neutralized by special antibacterial treatment and suitable for the required pH conditions. Sampling from the culture through a constant contact time, place the inoculated specimens and control pieces in a pipette dish, wash with neutralizing solution, shake slowly for exactly 1 minute and then dilute continuously. Incubate in a plate incubator at 30 ° C. for 48 hours.

* Antibacterial (antifungal)

1) Measurement standard-Measured according to ASTN G-21 method, strains used include Aspegillus Niger ATCC 9642, Penicillium Pinophilium ATCC 11797, Chaetomium Globosum ATCC 6205, Gliocladium Virens ATCC 9645, Aureobasidium Pullulans ATCC 15233. The degree of growth of the fungus is assessed 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.

Class 0: No mold growth.

Class 1: Growing up to 25% of the specimen area.

Class 2: Grown up to 26-50% of the specimen area.

Class 3: Grown up to 51-75% of the specimen area.

Class 4: Growing in excess of 75% of specimen area.

2) Method of measurement-After inoculating the specimen and the control specimen with a mixed spore suspension and incubating for a certain period of time, the growth status of the cultured mold was compared between the test specimen and the control specimen. It is a qualitative indication of the degree of antifungal properties. The size of the test piece is prepared by 50 × 50 cm 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 ioctyl 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 piece and the control piece placed in the container should be 50 mm x 50 mm, and three containers for the sample and the control piece should be prepared. Medium used was 0.7 g KH ₂ PO _4, 0.7 g K ₂ HPO ₄ , MgSOP ₄ .7H ₂ O 0.7 g, NH ₄ NO ₃ 1.0 g, NaCl 0.005 g, FeSO ₄ · 7H ₂ O 0.002 g, 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. This is sterilized for 20 minutes at a steam pressure of 1,055 g / cm 2 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 is prepared in advance the day before the use of the mixed spores, and sprayed the mixed spores on aging with a sterile sprayer on the test day. Incubate the specimens and control specimens in a plate incubator for 3 weeks at 28 ° C and 85% relative humidity.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Impact Strength (Kgcm / cm) 31 29 30 28 32 26 Fluidity (220 ℃, 10 Kg) 22 21 21 20 19 19 Injection Stability Thermal Stability (△ E) 0.8 1.0 0.8 2.0 0.7 2.3 Antimicrobial Evaluation Decay rate (%) 95 97 95 90 10 90 Antifungal 0 0 0 0 5 0

Through the Table 1, the impact strength and the strength even though the inorganic antimicrobial agent was added to the thermoplastic resin composition of Examples 1 to 3 prepared by adding the inorganic antimicrobial dispersion of the present invention compared to Comparative Example 1 prepared without using the inorganic antimicrobial agent There was no deterioration in mechanical properties such as fluidity, and the degree of discoloration was also good. In particular, the attenuation rate was measured at 95% or more, and the growth phenomenon of mold was not observed. In the case of Example 4 manufactured by the dry spraying method, the degree of discoloration was rather large in comparison with other methods in the manufacturing process, but it was confirmed that the antibacterial property was maintained.

On the other hand, in the case of Comparative Example 2 prepared by adding the inorganic antimicrobial at the time of injection / injection it was confirmed that the antimicrobial to some extent maintained but mechanical properties and discoloration is sharply reduced.

As described above, the thermoplastic resin composition of the present invention effectively induces the dispersion of the inorganic antimicrobial agent by introducing the inorganic antimicrobial component into the organic latex prepared by emulsion polymerization as a dispersion, thereby preventing mechanical property degradation and discoloration and antimicrobial activity There is an effect to improve.

Although described in detail above with reference to the specific embodiments of the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and such variations and modifications belong to the appended claims. It is also natural.

Claims (5)

A thermoplastic resin composition comprising 1 to 25 parts by weight of the inorganic antibacterial dispersion based on 100 parts by weight of the organic latex. Preparing an organic latex; Preparing a mixed solution by blending an inorganic antimicrobial dispersion in the organic latex; And Preparing the mixed solution into powder by agglomeration / drying or spray drying; Method (A) comprising, or Preparing an organic latex; And Preparing an inorganic antimicrobial dispersion in a powder range of -20 to 0 ° C. in the glass transition temperature range of the organic latex and then drying the organic latex to prepare a powder; Method for producing a thermoplastic resin composition, characterized in that any one method selected from the method (B) comprising a. The method of claim 1, The organic latex is at least one member selected from the group consisting of ABS (acrylonitrile-butadiene-styrene) resin, ASA (acrylonitrile-styrene-acrylate) resin, and MBS (methyl methacrylate-butadiene-styrene) resin Thermoplastic resin composition, characterized in that the use. The method of claim 1, The inorganic antimicrobial agent is selected from the group consisting of antimicrobial zeolite-based calcium phosphate and zirconium phosphate-based thermoplastic resin composition. The method of claim 1, The inorganic antimicrobial dispersion is prepared by adding 1 to 5 parts by weight of an emulsifier to 100 parts by weight of the inorganic antimicrobial agent according to claim 4 and stirring the mixture for 1 hour at a stirring speed of 5,000 rpm or more. .