JPH0710558B2 - Method for producing antibacterial molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an antibacterial property used for food / pharmaceutical packaging, tableware / medical equipment / optical equipment / electronic equipment packaging, or biophysical equipment. The present invention relates to a method for manufacturing a molded product.

[Prior Art] Conventionally, as a molded article of a resin containing an antibacterial inorganic substance, as shown in JP-B-58-33103, a sheet obtained by laminating a film containing a volatile additive, As disclosed in Japanese Examined Patent Publication No. 63-54013, molded articles such as granules, films and fibers made of a resin containing antibacterial zeolite are known.

[Problems to be Solved by the Invention] Conventionally, in a molded article of a resin containing an antibacterial inorganic substance containing a volatile additive, since the antibacterial substance is volatile,
It cannot exhibit antibacterial properties for a long period of time, and cannot maintain hygienic safety. On the other hand, a granular material made of a resin containing antibacterial zeolite, a film,
Molded articles such as fibers could not fully exhibit the antibacterial properties of antibacterial zeolite.

The present invention is to solve the above problems, it is possible to maintain the hygienic safety, antibacterial effect improved antibacterial effect compared to the conventional antibacterial zeolite-containing molded article of the same content It is an object to provide a zeolite-containing resin molded product.

[Means for Solving the Problems] In order to achieve the above object, the present invention is configured as follows. That is, the present invention relates to a method for producing an antibacterial molded article characterized in that a preformed body is stretched and molded into a three-dimensional shape by blowing a pressurized fluid into the preformed body made of a resin containing antibacterial zeolite. .

In the present invention, a resin containing an antibacterial zeolite as a preform such as parison is stretched, but the antibacterial zeolite exposed on the surface of the resin wall at the stage of the preform. Improve the exposure state of
In order to improve the exposed state of the antibacterial zeolite, which was buried in the vicinity of the surface of the resin wall at the stage of preforming, and in view of blow moldability, the stretching ratio is preferably 1.02 to 5 times. Further, in order to further improve the above effect, it is preferable to expand with a pressurized fluid set to a temperature lower than that of the preform and a temperature lower than that of the preform by 120 ° C.
Particularly preferably, the molecules are oriented in the tensile direction by stretching at a temperature not lower than the glass transition point and not higher than the melting point of the preform. Furthermore, it is possible to improve the exposed state of the zeolite by co-extruding the preform as a multi-layered parison consisting of a main layer containing no antibacterial zeolite and a skin layer of 2 to 100 μm composed of an antibacterial zeolite-containing resin. preferable. Specific examples of the multi-layer molded product include two or more multi-layer molded products such as an inner layer made of an antibacterial zeolite-containing resin, an outer layer made of an antibacterial zeolite-containing resin, and an inner and outer layers made of an antibacterial zeolite-containing resin. Is.

Incidentally, when obtaining a preform by melt-kneading the antibacterial zeolite-containing resin in an extruder, the antibacterial zeolite-containing resin adjusts the water content to 3000 ppm or less, preferably 1500 ppm or less to suppress the foaming phenomenon of the molded product. Above all preferred. The water content of the antibacterial zeolite-containing resin is the water content when supplied to the extruder for obtaining the preform, and the water content is the water content of the antibacterial zeolite and the water content of the thermoplastic synthetic resin. It is the calculated water content, and the crystal water in the antibacterial zeolite is not calculated. In addition, it is suitable to vacuum-dry at a heat treatment temperature of 200 ° C. or higher during the production of the antibacterial zeolite from the viewpoint of preventing the foaming phenomenon during the blow molding. The preferable heat treatment temperature is higher than the temperature at which the antibacterial zeolite-containing resin is melt-kneaded and plasticized during the production of the antibacterial molded article.

In the present invention, the antibacterial zeolite, natural zeolite, ion-exchangeable ions in synthetic zeolite, for example, sodium ions, calcium ions, potassium ions, magnesium ions, iron ions such as silver ions, copper The particle size of the antibacterial zeolite is 0.2 to 10 μm, preferably 0.2 to 3 μm, which is substituted with ions, zinc ions, ammonium ions, etc., because the exposed state of the antibacterial zeolite on the resin wall surface during molding is This is appropriate from the viewpoint of increasing the number and improving the stability of antibacterial activity. Here, the particle size is the arithmetic average value of the primary particle size measured by a scanning electron microscope.

In addition, the antibacterial zeolite-containing resin means that the antibacterial zeolite is 0.5 wt% or more and 60 wt% or less, preferably 2 wt% or more and 20 wt% or less in the thermoplastic synthetic resin, for example, high density polyethylene, It is a resin contained in high density polyethylene, low density polyethylene, polypropylene, ionomer, polyamide, polycarbonate, polyvinyl chloride, or olefin elastomer, urethane elastomer, amide elastomer and the like.

In general, an organic bactericide has a short expected period of its effect and also has a drawback that the effect is impaired over time. However, the antibacterial zeolite-containing resin used in the present invention is an antibacterial agent exposed on the resin wall surface. The antibacterial zeolite exerts a bactericidal effect, and ionized substances such as ionized silver in the antibacterial zeolite hardly elute outside, and the bactericidal effect can be exerted for a long time.

[Operation] In a preform made of a plasticized antibacterial zeolite-containing resin such as parison, the antibacterial zeolite is exposed in the resin wall surface of the preform because it is dispersed as islands in the resin. The amount of antibacterial zeolite is negligible. In the present invention, the antibacterial zeolite-containing resin wall is rapidly cooled by contacting with the pressurized fluid set to a low temperature by expanding the pressurized fluid set to a temperature lower than that of the preformed body. It is stretched as it goes. At this time, stretching acts on the boundary portion between the antibacterial zeolite and the resin of the preform, and the antibacterial zeolite exposed on the surface of the resin wall at the stage of the preform improves its exposed state, and The embedded antibacterial zeolite is exposed near the surface of the resin wall at the stage of preforming. Therefore, the exposed state of the antibacterial zeolite on the resin wall surface,
The so-called “cue-out state” is better than the molded product obtained by the conventional manufacturing method.

[Example] <Production of molded article> Example 1 A masterbatch containing 20% by weight of material (1) and 80% by weight of material (2) shown below was produced. Then, the water content of the masterbatch is 820 ppm (Karl Fischer method,
The mixture was treated at a heating furnace temperature of 250 ° C.), and the masterbatch and the material (2) were mixed at a mixing ratio of 1: 4 to obtain an antibacterial zeolite-containing resin.

Material (1): Antibacterial zeolite Average particle size 1.3 μm Bulk specific gravity 0.4, Silver ion exchange rate 2.5% Material (2): Polypropylene melt flow rate 1.0 [JIS-K-6758] Density 0.90 (Mitsubishi Noblene “MA-7”) ) Then, while the above-mentioned antibacterial zeolite-containing resin is melt-kneaded in the first extruder (screw diameter 40 mm), the resin consisting of only material B containing no antibacterial zeolite is used in the second extruder (screw diameter 40 mm) Was melt-kneaded.

An antibacterial zeolite-containing resin melt-kneaded by the first extruder and a resin containing no antibacterial zeolite melt-kneaded by the second extruder are formed into a co-extrusion die having a die diameter of 20 mm and a set temperature of 180 ° C. After supplying and laminating both materials in the die,
The inner layer was coextruded as a multi-layered parison having an antibacterial zeolite-containing resin and an outer layer made of a resin containing no antibacterial zeolite.

Then, the extruded multi-layer parison was placed between the molds of the division type, the molds were closed, and compressed air with a pressure of 6 kg / cm ² and a temperature of 20 ° C. was introduced into the multi-layer parison, and the multi-layer parison was held in the mold cavity. After expanding into a shape and cooling the molded product, the mold was opened to remove excess burrs to obtain a multilayer molded product A as shown below.

Molded product A Stretching ratio 1.2 times in the longitudinal direction and 1.8 times in the lateral direction Average wall thickness 800 μm (outer layer: 780 μm, inner layer 20 μm) Example 2 Except that the water content of the masterbatch was 1200 ppm,
A multilayer molded product B was obtained under the same mold and molding conditions as in Example 1 above.

Example 3 A resin comprising the material (1) was used to treat the masterbatch to a moisture content of 820 ppm, and a single layer extrusion head was used, and the same mold and molding conditions were used as in Example 1 above. A layered product C was obtained.

Comparative Example A resin composed of the material (1) was used to treat the masterbatch with a water content of 3200 ppm, which was extruded using a single-layer extrusion head, and then cooled and solidified as it was to form a cylindrical single-layer molding. Item D was obtained.

<Evaluation> Part of the molded articles obtained in Examples and Comparative Examples was cut out, and the exposed state of the antibacterial zeolite on the resin wall surface and the foamed state of the entire resin wall were evaluated.

<Evaluation result> As the means for evaluating the exposed state, the surface state was observed with an electron microscope, and the exposed state of the antibacterial zeolite of the single-layer molded article D was set to 100, and the number of particles exposed on the wall surface was expressed as a 100% ratio. In addition, as a means for evaluating the foaming state, one in which foaming is hardly noticeable by visual observation is ○,
The case where slight foaming occurred was evaluated as Δ, and the case where remarkable foaming occurred was evaluated as ×.

As a result of the above, the molded products A to C obtained by stretching the resin wall containing the antibacterial zeolite by blow molding are
The exposed state was improved as compared with the molded product D that was cooled and solidified as it was. Further, in the molded products A to C obtained with the water content of the masterbatch of the antibacterial zeolite-containing resin being 3000 ppm or less, the foaming phenomenon of the antibacterial zeolite-containing resin was hardly seen.

[Effect of the Invention] According to the present invention, pre-molding is performed by blowing a pressurized fluid into a pre-molded body made of an antibacterial zeolite-containing resin mixed with 0.5-60 wt% of antibacterial zeolite having a particle size of 0.2-10 μm. The body is stretched to a ratio of 1.02 to 5 times and blow molded into a three-dimensional shape, so the exposed state of the antibacterial zeolite on the resin wall surface can be improved, and food and medicine packaging tableware, medical equipment, and optical equipment -Useful as a packaging method for electronic devices or as a manufacturing method for bio-science and science equipment.

Claims (1)

[Claims] 1. A pressurized fluid is blown into a preformed body made of an antibacterial zeolite-containing resin containing 0.5 to 60% by weight of an antibacterial zeolite having a particle diameter of 0.2 to 10 μm.
Stretch the preform to a stretch ratio of 1.02 to 5 times,
A method for producing an antibacterial molded article, which is characterized by blow molding into a three-dimensional shape.