JPH03244663A - Transparent antibacterial sheet - Google Patents

Abstract

PURPOSE:To obtain an antibacterial sheet excellent in transparency by mixing a crystalline thermoplastic resin with a specified amount of solid zeolite particles holding metallic ions having an antibacterial action and rolling the mixture at a temperature below the melting point of the resin. CONSTITUTION:100 pts.wt. crystalline thermoplastic resin (A) (e.g. polypropylene or nylon 6) is mixed with 0.05-3 pts.wt. solid zeolite particles (B) holding metallic ions having an antibacterial action (e.g. copper ions). The obtained resin composition is rolled at a temperature below the melting point of component A to give a transparent antibacterial sheet having a resin layer with a haze of 15% or less. Since this sheet is transparent and has a function of preventing the occurrence of bacterial or microbial decay, contamination, etc., it can be widely used in applications, e.g. as the raw material and packaging material of foods, optical instruments, liquid crystal, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to a transparent antibacterial sheet material that has excellent transparency and antibacterial properties, but does not have any harmful effects on living organisms. [Conventional technology] Conventionally, antibacterial sheet materials made of plastic have been used mainly in food packaging, food processing, daily necessities, environmental equipment/materials, medical care/pharmaceuticals, electronics/engineering, etc. It is used to prevent microbial disasters such as spoilage and product deterioration. The following methods are already known for imparting antibacterial properties to these sheet materials: ・Blending antibacterial organic compounds ・Blending heavy metal powders, fibers, or knitted fabrics that exhibit antibacterial properties : ・Blending antibacterial heavy metal compound powder or particles ・Modifying the resin to impart antibacterial properties. Among these, compositions containing organic compounds are likely to be accompanied by a decrease in antibacterial properties due to elution, volatilization, or sublimation of the compound.
Furthermore, the blending of antibacterial heavy metal powders, etc. is not only difficult to achieve uniformly due to the large density difference with the resin, but also often results in a decrease in transparency due to the low affinity of the resin to the surface of the metal powder, etc. . Similar problems are often associated with formulations such as antibacterial heavy metal compound powders, and means for modifying resins may impair the advantages of the raw resin, so the scope of application is extremely limited. [Problems to be Solved by the Invention] In most of the above-mentioned conventional technologies, a sheet-like product is manufactured by kneading an antibacterial substance into a crystalline thermoplastic resin, but the lack of transparency due to crystallinity. Depending on the application, this becomes a major obstacle in developing applications for the sheet-like material. The present inventors have conducted extensive research on methods for obtaining a sheet-like material that has antibacterial properties and is also a crystalline thermoplastic resin with excellent transparency. [Means for solving the problem] As a result, when a crystalline thermoplastic resin composition containing a zeolite antibacterial agent in a specific proportion is rolled, the transparency of the sheet material is significantly improved, and the antibacterial The present invention was completed based on this finding. As is clear from the above description, an object of the present invention is to provide a transparent antibacterial sheet material having excellent transparency and sufficient antibacterial properties, and a method for producing the same. That is, the present invention provides a resin composition mainly composed of 100 parts by weight of a crystalline thermoplastic resin and 0.05 to 3 parts by weight of zeolite solid particles holding metal ions exhibiting antibacterial activity, which is made transparent by rolling. It consists of a transparent antibacterial sheet-like material (a concept that includes both sheets and films) and the transparent antibacterial sheet-like material. In the present invention, both natural zeolite and synthetic zeolite can be used as the zeolite. Zeolite is a general term for aluminosilicates that generally have a three-dimensional skeleton structure, and is expressed by one of the following general formulas depending on the valence of the metal rMJ contained: mMio・A1tOs'pSfO1qHaO (M is a monovalent Gold H)mMllAlxOs・psiolqHzo
(M is a divalent metal) mMaolAlaOs・psi0
1qH*o (M is a trivalent metal) (where M represents an ion exchangeable ion, usually a mono- or divalent metal ion. m and p are the coefficients of metal oxide and silica, respectively) , q represents the number of water of crystallization) Specific examples of zeolites include A-type zeolide, X-
type zeolide, Y-type zeolide, T-type zeolide,
Examples include, but are not limited to, high silica zeolite, sodalite, mordenite, alcyme, clinoptilolite, chabasite, erionite, and the like. The zeolite-based solid particles holding metal ions exhibiting antibacterial activity of the present invention refer to some of the ion-exchangeable metal ions in the zeolite, such as sodium ions, calcium ions, potassium ions, magnesium ions, iron ions, etc. All of the components have been replaced with antibacterial metal ions. Examples of antibacterial metal ions include silver, copper, lead,
ions of tin, chromium, cadmium, zinc, bismuth or thallium, preferably silver, copper or zinc ions. The content ratio of each metal exhibiting a bactericidal effect to the total amount of zeolite (based on the weight of anhydrous zeolite) is as follows: Silver: 30% by weight or less, preferably 0.00% by weight or less
1 to 5% by weight; in the case of copper or zinc, up to 35% by weight, preferably 0.
01 to 15% by weight; When two or more of silver, copper, and zinc ions are used together, the sum of these ions is preferably in the range of 0.001 to 15% by weight. In addition, metal ions other than silver, copper or zinc ions, for example,
There is no problem even if ions such as sodium, potassium, calcium, or ammonium ions coexist in amounts that do not interfere with the bactericidal effect. Part by weight of antibacterial zeolite solid particles holding antibacterial metal ions in the transparent antibacterial sheet of the present invention (
(based on anhydrous zeolite) is 0 based on the weight percent of crystalline resin.
．． The amount is set in the range of 0.05 to 3 parts by weight, preferably 0.1 to 2 parts by weight, and more preferably 0.2 to 1 part by weight. If the amount of antibacterial zeolite solid particles holding antibacterial metal ions is less than 0.05 parts by weight, sufficient antibacterial properties will not be exhibited, and if the amount exceeds 3 parts by weight, the antibacterial properties will be reduced during rolling. It becomes difficult to obtain a transparent sheet-like product since the tendency of the sheet to whiten, become perforated or cut becomes difficult to ignore. Examples of the crystalline thermoplastic resin used in the present invention include the following: High-density polyethylene (H
DPE), medium density polyethylene (MDPE), linear low density polyethylene (L-LDPE) or ultra-high molecular weight polyethylene (UHMW-PE); homopolymerized polypropylene or copolymerized polypropylene; in addition to poly-1-butene, etc., ethylene or polyolefin resins such as copolymers containing propylene as a main component and other α-olefins or polar monomers; polyamide resins such as nylon-6, nylon-6,6, nylon-11, nylon-12, etc. ; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyacecool resins; and mixtures of two or more of these resins, as long as they are crystalline thermoplastic resins, depending on the type of raw material resin. There are no restrictions. Among these, crystalline polyolefin resins are preferred from the standpoint of practicality, ease of processing, and the like. In addition, modified resins obtained by copolymerizing or grafting unsaturated carboxylic acids such as maleic acid, acrylic acid, and fumaric acid, and derivatives such as their acid anhydrides or esters to the above resins, or treating the above resins with ionizing radiation, Modified resins crosslinked with a crosslinking agent can also be used depending on the application. In the present invention, various fillers (or reinforcing materials) may be added to the crystalline thermoplastic resin in an amount that does not substantially reduce its transparency. Fillers that can be used include fibrous reinforcing materials such as glass fiber, carbon fiber, and vinylon fiber, flake fillers such as mica and talc, spherical fillers such as glass peas, and amorphous fillers such as calcium carbonate, wood chips, and wood powder. can be mentioned. The surface of these fillers (or reinforcing materials) is preferably subjected to a treatment that imparts affinity to the resin to be blended. Examples of such treatment include addition of an unsaturated carboxylic acid or its acid anhydride, addition of an unsaturated amine, and rubber coating. In addition to these fillers, a moisture absorbent, an extender, a coloring agent, a flame retardant, an anti-deterioration agent, an antistatic agent, a lubricant, etc. can be added as necessary. In the present invention, the crystalline thermoplastic resin and zeolite solid particles holding metal ions exhibiting an antibacterial effect are melt-kneaded, and a film is formed by a known molding method such as a T-die method or an inflation method. A rolling process is performed on the rolled sheet material. The rolling in the present invention must be carried out between one or more pairs of rolls at a temperature below the melting point (defined later) of the crystalline thermoplastic resin. If an attempt is made to roll the sheet at a temperature higher than the melting point of the crystalline thermoplastic resin, the sheet will melt and rolling will not take place. This can cause problems such as adhesion to surfaces. The melting point of the resin in the rolling process of the present invention is defined by JIS K
It refers to the temperature at which the maximum peak of the thermal behavior curve of the resin is obtained using a DSC (differential scanning calorimeter) in accordance with 7121. Further, the rolling operation may be repeated or the sheet-like material may be preheated before rolling, if necessary. In order to improve the transparency of the sheet, the surface roughness of the rolling roll used to produce the transparent antibacterial sheet of the present invention is usually less than IS, preferably less than 0.5S, more preferably less than 0.5S. Set to 2S or less. The rolling reduction ratio (r:%), which is one of the requirements for rolling conditions in the present invention, can be expressed by the following formula from the thickness of the material resin before rolling (hl) and the thickness of the sheet after rolling (h2). can. r=100” (hi ha )/h+ (%
) The final rolling reduction ratio of the rolled film or sheet (sheet-like material) is preferably set in a range of 50% or more and 90% or less, more preferably 60% or more and 85% or less. The transparent antibacterial sheet material of the present invention conforms to ASTM DIO03.
The haze measured according to the method is 15% or less, preferably 8%.
The content is more preferably 5% or less. [Examples] The present invention will be explained in more detail below using Examples and Comparative Examples, but the present invention is not limited thereto. The zeolite-based solid particles holding metal ions exhibiting antibacterial action (hereinafter referred to as "antibacterial agent") used in the examples are commercially available under the trade name "Bactekiller BM103J (manufactured by Kobo)." is a powder containing 3.5% by weight of silver in A-type zeolide, and has a particle size of 2 μm.In addition, when performing melt kneading and film formation by rolling, the antibacterial agent is added in advance. The crystalline thermoplastic resin containing the following was heated in a heating oven at 120°C for 8 hours or more before being subjected to processing. Rolling suitability was evaluated based on whether whitening, holes, breaks, etc. occurred in the sheet material during the rolling process. If a uniform transparent sheet was obtained, it was marked as ×, and if a uniform transparent sheet was obtained, it was marked as ○. Antibacterial properties were evaluated from the killing rate of viable bacteria measured by the method shown below. A result with a killing rate of 90% or more was marked as “○”. , results of less than 90% were expressed as "x". The sample bacterial solution contains Escherichia coli as a test bacterial strain.
h-ia coil IFO3301) or Staphylo-coccus aureus
IFo 13276) using normal bouillon medium.
After culturing overnight at <RTI ID=0.0>C,</RTI> the mixture is diluted with sterile physiological saline so that the number of bacteria per 11 liters is about 10' to 10'. A fixed amount of the bacterial solution is sprayed onto one side of the sample sheet, and the surface of the sample sheet is wiped with sterile gauze immediately after spraying and after being left at 35° C. for 18 hours. The test bacteria attached to this gauze are extracted with 5CDLP broth medium to make a test solution, and the number of viable bacteria in this test solution is determined by 5C
Conventional pour plate culture method using DLP agar medium (37°C,
The killing rate is calculated from the number of viable bacteria adhering to the sample surface immediately after spraying and after 18 hours. Examples 1 to 3 and Comparative Examples 1 to 3 Polypropylene homopolymer (abbreviated as PP, melt flow rate 1.0 g 710 minutes, density 0.90 g / c
c, melting point 162°C) and 0.5 parts by weight, 1 part by weight, or 2.5 parts by weight of the antibacterial agent were melt-kneaded in a granulator, and then mixed to a thickness of 1 by T-die method. Three types of rolling sheets with different antibacterial agent concentrations (74% rolling degree) were prepared with a width of .5 ma + width of 250 mm. The above rolling sheet was supplied to a pair of upper and lower rolls with a roll diameter of 300 mm and a width of 400 mm, and the roll temperature was 110°C.
Three types of rolled sheets with a thickness of 0.40 mm and different concentrations of antibacterial agents were obtained (reduction ratio of 73%). Table 1 shows the transparency (Ilk degree) and antibacterial properties of each sheet. Further, as Comparative Examples 1.2 and 3, Table 1 shows the results of cases in which no antibacterial agent was included, and cases in which 0.02 parts by weight or 10 parts by weight of an antibacterial agent were included. Examples 4-6 and Comparative Examples 4-5 Ethylene-propylene random copolymer (rR-PP
Abbreviated as J. Melt flow rate 2.2 g 710 min, density 0.90 g/cc, melting point 142 °C, ethylene content 4 mol% and propylene content 96 mol%) 100
parts by weight and 0.5 parts by weight, 1 part by weight or 1.5 parts by weight of the antibacterial agent.
After melt-kneading each composition consisting of parts by weight in a granulator,
Three types of rolling sheets (haze of 29%) with different antibacterial agent concentrations were formed using the T-die method with a thickness of 1.5 mm and a width of 250 am. Each of the above sheets was supplied to a rolling roll with a roll diameter of 300 mm and a width of 400 mm, and rolled at a roll temperature of 90°C to obtain three types of rolled sheets (transparent sheets) with a thickness of 0.42 mm and different antibacterial agent concentrations. was obtained (reduction rate of 72%). Table 1 shows the transparency and antibacterial properties of each sheet. Furthermore, as Comparative Examples 4 and 5, Table 1 shows the results of cases in which no antibacterial agent was included and cases in which 0.02 parts by weight of an antibacterial agent was included. Example 7 and Comparative Example 6 Ethylene-brobylene block copolymer [rB-PP
Abbreviated as J. Melt flow rate (MFR) 0.5g/
10 minutes, density 0.91 g/cc, melting point 160°C, ethylene content 8 mol% and propylene content 92 mol%]
A composition consisting of 100 parts by weight and 1 part by weight of the antibacterial agent was kneaded using a granulator, and the mixture was mixed using a T-die method to a thickness of 2.3 mm x width of 2.
A 50mm sheet was formed into a rolling sheet (haze level 80).
%)It was created. This sheet was rolled in the same manner as in Example 1 to obtain a film with a thickness of 0.35 mm (rolling ratio: 85%).
). Table 1 shows the transparency and antibacterial properties of the film. Further, as Comparative Example 6, the results when no antibacterial agent was included are shown in Table 1. Examples 8 and 9 and Comparative Example 7 Made of high-density polyethylene homopolymer [abbreviated as rPEJ]. Melt index (MI) 0.8g710
min, density 0.94 g/cc, melting point 130℃ 110
0 parts by weight and 1 part by weight or 2 parts by weight of the antibacterial agent were kneaded in a granulator, and two types of rolling sheets (!l degree of 92%) with a thickness of 2.2 mm and a width of 250 mm were prepared using a T-die method. Created 0
Both sheets were rolled in the same manner as in Example 1 at a rolling temperature of 90°C to obtain a rolled sheet with a thickness of 0.45 mm (rolling reduction rate of 80%).
). Table 1 shows the transparency and antibacterial properties of both sheets. Additionally, Table 1 also shows the results of Comparative Example 7 in which no antibacterial agent was included. [Effects of the Invention] The sheet-like material of the present invention has antibacterial properties and is transparent even though it is formed of a crystalline thermoplastic resin. The sheet according to the present invention is not only transparent, but also has the ability to prevent spoilage caused by bacteria and microorganisms, as well as product deterioration and contamination. Can be used in a wide range of applications such as equipment-related, precision photography-related, food-related, liquid crystal-related, medical-related materials, packaging, etc.

Claims (2)

[Claims] (1) 0.0 zeolite solid particles holding metal ions with antibacterial activity in 100 parts by weight of crystalline thermoplastic resin
5 to 3 parts by weight, and the haze of the resin layer is 15% or less. (2) 100 parts by weight of crystalline thermoplastic resin and 0.0 parts by weight of zeolite solid particles holding metal ions having antibacterial activity.
1. A method for producing a transparent antibacterial sheet, comprising rolling a resin composition containing 5 to 3 parts by weight of the thermoplastic resin at a temperature below the melting point of the thermoplastic resin.