JPH10279815A - Antibacterial resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin compsn. which can give moldings, films, and sheets having antibacterial properties and transparent appearance with little cloudiness by compounding a thermoplastic resin with a specified amt. of zinc carbonate. SOLUTION: This compsn. comprises 99.9-80 wt.% thermoplastic resin and 0.1-20 wt.% zinc carbonate. The resin can be arbitrarily selected from among thermoplastic resins usually used as the raw materials in injection molding or extrusion, one moldable at 300 deg.C or lower being pref. Pref. thermoplastic resins are a styrene resin, a methacrylic resin, and a polycarbonate resin, the former two resins being esp. pref. Zinc carbonate used here is one generally called 'basic zinc carbonate', 'zinc carbonate.hydroxide', or 'transparent zinc white', is represented by the formula: xZnCO3 .yZn(OH)2 .zH2 O (x is 2; y is 2; and z is 1), and pref. has a particle size of 0.1-30 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a thermoplastic resin composition having excellent antibacterial properties.

[0002]

2. Description of the Related Art Thermoplastic resins are used in a wide range of fields such as electronics / electricity, home appliances, automobiles, sanitary fields such as toilet seats and kitchen / bathroom areas, and miscellaneous goods.
In recent years, it has been pointed out that bacteria and molds proliferate in products used for these, and have a bad effect on human bodies.

[0003] A method of imparting antibacterial properties to a thermoplastic resin is as follows.
There are two methods of kneading the antimicrobial agent into the thermoplastic resin or applying the antimicrobial agent to the surface of the thermoplastic resin product.
At present, inorganic antibacterial agents are mainly used as kneading antibacterial agents, while organic antibacterial agents are mainly applied in liquid form to products. Representative examples of inorganic antibacterial agents include zeolites and synthetic minerals substituted with metals such as silver,
Examples of the organic antibacterial agent include chlorohexidine and quaternary ammonium salts.

[0004] The addition of zinc carbonate to a thermoplastic resin is described, for example, in JP-A-63-179934, in which a vinyl chloride resin sheet is added together with an antibacterial agent (N (fluorodichloromethylthio) phthalimide powder). JP-A-2-255844 is characterized in that it contains a zeolite holding an antibacterial metal ion and a basic metal compound for the purpose of suppressing coloring when the antibacterial zeolite is mixed with the resin. It describes a resin composition and mentions basic zinc carbonate as one of the basic metal compounds. In Japanese Patent Application Laid-Open No. 8-100102, for the purpose of producing a fungicide / antibacterial polyacetal resin,
Polyacetal resin, antioxidant, specific zinc compound,
An invention relating to a resin composition comprising an organic compound such as tetrachloroisophthalonitrile is disclosed, and specific zinc compounds are exemplified.

[0005] However, there has been no example in which a zinc compound is added to a styrene resin or a methacrylic resin. In general, antibacterial agents have been developed mainly for olefin-based resins, and many are effective with olefin-based resins, but the effects of amorphous styrene-based resins and methacrylic-based resins are known. Not. As an example of a transparent antibacterial thermoplastic resin, Japanese Patent Application Laid-Open No. 5-140331 proposes a method of adding zinc oxide fine particles having a particle size of 0.1 μ or less, and a film having a thickness of 0.2 μm. The effect is described. According to this method, it is difficult to produce zinc oxide fine particles, and the cost is industrially high. Further, it is difficult to knead bulky because of the fine particles. Also, Japanese Patent Application Laid-Open
JP-A-311239 also discloses a transparent antibacterial resin composition comprising a transparent thermoplastic resin, an inorganic antibacterial agent having an average particle diameter of 1 μm or less, and a lubricant, but does not disclose zinc carbonate.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive resin composition which can be easily kneaded into a molten resin and has antibacterial properties. It is still another object of the present invention to provide a resin molded product, a film, and a sheet having antibacterial properties and having a low turbidity with a transparent feeling.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, zinc carbonate was added to thermoplastic resins, particularly styrene resins, methacrylic resins, and transparent thermoplastic resins. They have been found to have excellent antibacterial properties as well as good transparency and have reached the present invention. That is, in the present invention, (1) the thermoplastic resin is 99.
(1) The antibacterial resin composition comprising 9 to 80% by weight of zinc carbonate and 0.1 to 20% by weight of zinc carbonate, and (2) the thermoplastic resin is a styrene resin. (3) The thermoplastic resin is a methacrylic resin, and (4) the thermoplastic resin is transparent. The antibacterial resin composition according to the above (1), which is a thermoplastic resin.

Hereinafter, the present invention will be described in detail. The thermoplastic resin used in the present invention can be arbitrarily selected from thermoplastic resins used as a raw material in ordinary injection molding or extrusion molding. Resins are preferred. Such materials include, for example, styrene resins, olefin resins, methacrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyamide resins, polyester resins, polyurethane resins, polycarbonate resins, polyacetal resins. , Fluororesins and various thermoplastic elastomers, and alloys with these resins.

Of these, styrene resins, methacrylic resins and polycarbonate resins are preferred, and styrene resins and methacrylic resins are most preferred. Examples of the styrene resin used in the present invention include those generally used for molding, such as styrene homopolymer (PS), high impact polystyrene (HIPS), and methyl methacrylate / styrene copolymer. (MS), methyl methacrylate / butadiene / styrene copolymer (MBS), styrene / maleic anhydride copolymer (SMA), styrene / methacrylic acid copolymer (SMAA), α-methylstyrene or maleimide Heat-resistant styrene resin, styrene-acrylonitrile-based copolymer resin, α-methylstyrene-acrylonitrile-based copolymer resin, furthermore, polyphenylene ether-based resin and alloy of polyphenylene ether-based resin and thermoplastic resin other than polyphenylene ether-based resin Such as Can be.

The styrene / acrylonitrile copolymer resin includes acrylonitrile / styrene copolymer (AS), acrylonitrile / styrene / butadiene copolymer (ABS), and acrylonitrile / styrene / acryl rubber copolymer (AAS). Copolymerized with acrylonitrile-styrene-chlorinated polyethylene copolymer (ACS), acrylonitrile-styrene-ethylene-propylene rubber copolymer (AES), acrylonitrile-styrene-ethylene-vinyl acetate copolymer, α-methylstyrene or maleimide Examples of the heat-resistant ABS resin obtained by polymerization include α-methylstyrene / acrylonitrile copolymer resin, in which the styrene portion of the styrene / acrylonitrile copolymer resin is replaced with α-methylstyrene. α It may be mentioned methyl styrene-acrylonitrile copolymer resin.

The methacrylic resin preferably used in the present invention includes, for example, methyl methacrylate homopolymer, styrene, α-methylstyrene, acrylonitrile, various acrylates and methacrylates in addition to methyl methacrylate. A methacrylic resin whose various properties have been improved by copolymerizing other monomers, and a polymer mainly composed of acrylate or methacrylic acid ester or a polymer mainly composed of butadiene, methyl methacrylate, styrene, acrylonitrile And impact-resistant methacrylic resins obtained by graft copolymerization of various acrylates and methacrylates.

The transparent thermoplastic resin suitably used in the present invention includes styrene resins, olefin resins, methacrylic resins, polyvinylidene chloride resins, polyamide resins, polyester resins, polycarbonate resins, and various types of thermoplastic resins. Thermoplastic elastomers, and styrene resins include general-purpose polystyrene (GPP).
In addition to S), transparent HIPS is included. Further, examples of the thermoplastic elastomer include a styrene-butadiene block copolymer and a hydrogenated product thereof.

[0013] These thermoplastic resins preferably have a weight average molecular weight (Mw) of 1,000 to 1,000,000, and more preferably 10,000 to 1,000,000.
000, particularly preferably 50,000 to 800,000
Is in the range. Further, these thermoplastic resins may be used alone or in combination of two or more kinds as a polymer alloy.

The zinc carbonate used in the present invention is generally called basic zinc carbonate, zinc carbonate / hydroxide, or transparent zinc white. The general formula is xZnCO 2 .y Zn
It is represented by (OH) 2.zH2O. Typically x = 2,
Those with y = 3, z = 1 or x = 3, y = 6, z = 2 are well known, but the composition is undefined. The addition amount of zinc carbonate is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, and particularly preferably 0.8 to 5% by weight. When the amount is small, the antibacterial effect is not obtained, and when the amount is large, the impact strength and the transparency are reduced.

The particle size of zinc carbonate is preferably fine, but is preferably from 0.1 to 30 μm, more preferably from 0.2 to 20 μm, particularly preferably from 0.5 to 10 μm as long as it is practically available. The production method is not particularly limited. For example, it is produced by allowing soda ash (sodium carbonate) to act on a zinc salt solution. In the present invention, more preferable results can be obtained by adding a salt of an organic carboxylic acid and a metal. The salt of the organic carboxylic acid and metal used is 0.0
The content is preferably 1 to 10% by weight, more preferably 0.1 to 10% by weight.
5% by weight, particularly preferably 0.5 to 4% by weight, most preferably 0.8 to 3% by weight is added.

Examples of the organic portion of the salt of an organic carboxylic acid and a metal which can obtain more preferable results when added to the present invention include a hydrocarbon group, an aromatic compound, an alicyclic compound and the like. Examples of specific organic carboxylic acids include stearic acid, montanic acid, behenic acid, lauric acid, myristic acid, palmitic acid, lactic acid, butyric acid, acetic acid, maleic acid, oleic acid, stearoyl lactic acid, pantothenic acid, succinic acid, Aliphatic carboxylic acid salts such as 12-hydroxystearic acid, fumaric acid, tartaric acid, gluconic acid, cyclohexylbutyric acid, ethylenediaminetetraacetic acid, etc .; Examples include acids, alkyl ether carboxylic acids, N-acyl amino acids, acylated peptides and the like. Among these, an alkyl carboxylic acid is preferable, and a compound having 6 or more carbon atoms is more preferable.

In the present invention, the metal of the salt of a metal with an organic carboxylic acid is defined as Group I or II except for hydrogen in the periodic table.
Group, group III except boron, group IV except carbon, group V except nitrogen, phosphorus and arsenic, Po and III, IV, V, V
It means each element belonging to each subgroup a of Group I and VII. For example, Li, Na, K, Rb, Cs, Mg, Ca, Sr,
Ba, Sc, Y, La, Ce, Pr, Nd, Pm, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
b, Lu, Ti, Zr, Hf, V, Nb, Ta, Cr,
Mo, W, Mn, Tc, Re, Fe, Ru, Os, C
o, Rh, Ir, Ni, Pd, Pt, Cu, Ag, A
u, Zn, Cd, Hg, Al, Ga, In, Tl, S
i, Ge, Sn, Pb, Sb, Bi and the like. Among them, Zn, Na, Al, Mg, Ba, Ca, and K are easily available and more preferable.

The organic carboxylic acid and metal salt preferably used in the present invention may be used alone or in combination of two or more.
For example, a zinc stearate / barium stearate complex, a zinc stearate / calcium stearate complex, and the like can be given. The method for producing the antimicrobial resin composition of the present invention is not particularly limited, and after mixing the above components at a predetermined mixing ratio with a Henschel mixer or a tumbler, a single-screw or multi-screw extruder, a Banbury mixer,
It can be obtained by melt-kneading using a known kneading device such as a kneader or a roll. Alternatively, the raw materials can be obtained by supplying various raw materials to a melt-kneading apparatus using separate feeders without mixing the raw materials with a Henschel mixer or a tumbler, and kneading the raw materials.

In the present invention, if necessary, various additive components such as a plasticizer, a lubricant, a stabilizer, an antioxidant, an ultraviolet absorber, a flame retardant, a release agent and the like are polymerized. It can also be added at the time of molding of the polymer molded article. The antibacterial resin composition of the present invention obtained in this manner can be obtained by a known method generally used for molding a thermoplastic resin composition, such as injection molding, extrusion molding, blow molding, inflation molding, vacuum molding, and the like. The molded article is formed into various molded articles by the above method. Further, after being formed into a film, a biaxially stretched film, a sheet, a foamed sheet, a foamed bead or the like, it is formed into a desired formed body. In particular, when used for films and sheets, a product having higher transparency can be obtained.

The molding of the kneaded molded body is preferably performed at a temperature of 260 ° C. or lower, more preferably at a temperature of 240 ° C. or lower. This can prevent bubbles from being mixed into the molded body due to decomposition of zinc carbonate.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. In addition, the measuring method of each physical property is shown below. (1) Antibacterial test A flat molded body (thickness: 2 mm) of the resin composition was subjected to 50 mm x 5
The molded product was cut into 0 mm, wiped clean with a gauze impregnated with ethanol, and allowed to stand at 23 ° C. and a relative humidity of 60% for 24 hours to obtain a sample for an antibacterial test. A test sample was inoculated with 0.5 ml of a bacterial solution, and 45 mm × 4
After a 5mm polyethylene film is adhered, 37 ℃
And at the start of storage and 24 hours later, viable bacteria are washed out with an SCDLP medium (Nippon Pharmaceutical Co., Ltd.).

The number of surviving bacteria was measured on the washed solution by an agar plate culture method (37 ° C., 24 hours) using a standard agar medium for measuring the number of bacteria (manufactured by Nissui Co., Ltd.). Convert to the number of surviving bacteria. The test results are expressed as the logarithmic value of the difference in the number of viable bacteria from the blank. Since it is a logarithmic value, a difference of 1 indicates that a single digit value is different. That is, the larger the value, the greater the effect.

The test bacterium was Escherichia coli (IFO3301).
It was used. The test bacterial solution is prepared by suspending Escherichia coli in a solution prepared by dissolving 5 mg of meat extract, 10 mg of peptone, and 5 mg of sodium chloride in 1 liter of distilled water, and adjusting the number of bacteria per ml to about 10 ⁶ . (2) Raw materials used As the thermoplastic resin, rubber-reinforced polystyrene (HIPS)
-1) Styron (trade name, manufactured by Asahi Kasei Corporation) is used. In addition, rubber reinforced polystyrene (HIPS-2) to which 0.5% by weight of zinc stearate is added during the manufacturing process is used.

As general-purpose polystyrene (GPPS), polystyrene having a weight average molecular weight of 210,000 and containing no additives is used. As the methacrylate resin (PMMA), Delpet 60N (trade name, manufactured by Asahi Kasei Corporation) is used. As the zinc carbonate, zinc oxide and active zinc oxide, those manufactured by Shodo Chemical Co., Ltd. are used (the numbers in parentheses in the table indicate the average particle size).

As the zinc stearate and the magnesium stearate, special grade reagents manufactured by Wako Pure Chemical Industries, Ltd. are used.

[0026]

Examples 1 to 10 and Comparative Examples 1 to 6 After dry-blending the composition shown in Table 1, melt-kneading was performed at a kneading temperature (cylinder-set temperature) of 220 ° C. using a single screw extruder, and pelletizing was performed to obtain a resin composition. Get things. A pellet (100 mm × 100 mm × 2) for a test was obtained by pelletizing the obtained resin composition with an injection molding machine (manufactured by FANUC CORPORATION, trade name: Autoshot 50C)
mm (t)). The cylinder set temperature of the molding machine is 210 ° C., and the mold temperature is 60 ° C.

Tables 1 and 2 show the results of the antibacterial test of the obtained resin molded product.

[0028]

[Table 1]

[0029]

[Table 2]

As shown in Table 1, all of the resin molded articles of the examples exhibited excellent antibacterial performance, and were compared with the zinc oxides and active zinc oxides of Comparative Examples 2 and 3 in comparison with the average particle size. Is excellent in haze. In addition, in the comparison of Examples 1, 2, and 4, the effect of adding a salt of an organic carboxylic acid and a metal shows an improvement in haze. Table 2 shows the effect of adding zinc carbonate to each resin other than general-purpose polystyrene. The resin molded articles of the examples show better antibacterial properties than the comparative examples 4 to 6.

[0031]

The antibacterial resin composition of the present invention exhibits excellent antibacterial activity. The antimicrobial resin composition of the present invention shows good transparency when added to a transparent resin. For this reason, the antibacterial resin composition of the present invention has a wide range of applications, for example, various OA equipment and home appliances, refrigerator components, or toilet seats,
Various sanitary products such as wash basin parts, other building materials,
It is suitable for a wide range of uses such as vehicle parts, daily necessities, toys, and miscellaneous goods.

Claims (4)

[Claims] 1. An antibacterial resin composition comprising 99.9 to 80% by weight of a thermoplastic resin and 0.1 to 20% by weight of zinc carbonate. 2. The antibacterial resin composition according to claim 1, wherein the thermoplastic resin is a styrene resin. 3. The antibacterial resin composition according to claim 1, wherein the thermoplastic resin is a methacrylic resin. 4. The antibacterial resin composition according to claim 1, wherein the thermoplastic resin is a transparent thermoplastic resin.