JP4737129B2 - Photocatalytic apatite-containing resin and method for producing the same - Google Patents

Description

  The present invention relates to a resin containing an antibacterial agent, and more particularly to a resin containing a photocatalytic apatite and a method for producing the same.

A portable device such as a portable information device or a cellular phone touches a human hand, and dust or the like adheres to it via hand grease or tobacco tar. These hand fats, tobacco tar, and dust propagate germs. This impairs the appearance and cleanliness of the portable device. On the other hand, interest in antibacterial activity is increasing. For this reason, cases such as portable information devices and mobile phones, operation keys, and the like have been strongly required to have antibacterial measures. Generally, titanium oxide (TiO2) is used as these antibacterial agents. For example, a coating resin in which titanium oxide is mixed in a resin is prepared, and this coating resin is laminated on the housing through a protective film on the housing resin. The key is coated with a coating resin containing titanium oxide on the surface. As described above, Patent Documents 1 and 2 are keys using titanium oxide.
JP-A-9-102238 JP, 11-195345, A There is also a coating resin in which titanium oxide is microencapsulated and mixed into the resin. A material using such a coating resin as a key is described in Patent Document 3. JP-A-9-190254 Japanese Patent Application No. 2002-146110

  However, in Patent Documents 1 to 3, since it is necessary to form a coating layer on a resin molded product for antibacterial purposes, the number of manufacturing steps increases and the cost increases. Further, in Patent Documents 1 to 3, every time a coating film containing an antibacterial agent is pressed, the film is scraped little by little, and eventually the film disappears and the antibacterial action is lost.

  As these measures, it is conceivable to mix an antibacterial agent directly into the resin. However, this method degrades the resin on which the titanium oxide, which is an antibacterial agent, is based. In other words, titanium oxide causes so-called choking that the resin surface is gradually powdered and weathered. In recent years, photocatalytic apatite, which has been studied as an antibacterial agent instead of titanium oxide, is also considered to cause choking similarly to titanium oxide. For this reason, as described in Patent Document 4 below, photocatalytic apatite is Even when used as an antibacterial agent, a coating resin was made and an antibacterial coating layer was formed on the surface of the resin molded product.

  However, the inventors have discovered that photocatalytic apatite does not cause so-called choking that weathers the resin.

  The object of the present invention is to easily manufacture an antibacterial resin molded product, reduce the number of manufacturing steps, reduce the manufacturing cost, and even if the antibacterial resin molded product surface is scraped, the antibacterial action is not reduced. Furthermore, a resin that does not cause choking by an antibacterial agent, and a method for producing the same are provided.

The present invention includes a step of directly kneading a photocatalyst having a chemical structure in which a part of Ca of calcium hydroxyapatite is substituted with Ti and a resin material to form a resin composition, and heat-melting and injecting the resin composition And a process for producing a resin molded product . Photocatalyst as described above does not cause so-called chalking to weathering of the resin. For this reason, a photocatalyst can be directly mixed into the resin to constitute the entire molded product. Therefore, even if the resin surface is scraped off, the antibacterial action does not decrease. Production of the resin molded article containing the photocatalyst is easily possible inexpensive cost can be reduced number of manufacturing steps. The photocatalyst force decomposes bacteria compared with titanium oxide, bacteria, dust, etc., strong other words the antibacterial.

  The photocatalyst having a chemical structure in which a part of Ca of calcium hydroxyapatite used in the present invention is substituted with Ti is a combination of Ti oxide having a photocatalytic function and apatite at an atomic level. Such photocatalytic apatite itself is disclosed in Japanese Patent Application Laid-Open No. 2000-327315, and FIG. 3 shows the surface chemical structure of Ti—CaHAP.

  The resin molded product containing a photocatalyst having a chemical structure in which a part of Ca of the calcium hydroxyapatite of the present invention is substituted with Ti is easy to manufacture the resin molded product, suppresses the manufacturing man-hours, and reduces the manufacturing cost. Even if the surface of the resin molded product is scraped off, the antibacterial action is not reduced, and further choking by the antibacterial agent can be prevented.

  Examples of the present invention will be described.

  A method for producing a resin containing resin and photocatalytic apatite will be described below.

(1) First, prepare photocatalytic apatite (product name: PCAP-100, manufactured by Taihei Chemical Co., Ltd.) and resin, specifically, polypropylene (manufactured by Nippon Polyolefin Co., Ltd.).
Three types of photocatalytic apatites with an average particle size of 20 (μm), 10 (μm) and 5 (μm) were prepared. In addition to the above polypropylene, polyethylene, nylon, polyethylene terephthalate, polystyrene, polycarbonate and the like can be used as the resin.
(2) Next, the prepared photocatalytic apatite and polypropylene are kneaded.
Kneading is performed using a kneading machine (product name KZW-15, manufactured by Technobel Corp.). The kneading conditions are 190 ° C. and 5 to 30 minutes. Photocatalytic apatite and polypropylene were mixed uniformly under the above conditions. After this, the kneaded product was cooled and then cut into pellets (diameter 2 mmΦ × length 3 mm). Four types of samples 1, 2, 5, and 6 were produced by the above method. Other than these, Sample 3 has no antibacterial agent added. Sample 4 is obtained by adding titanium oxide. Details of each sample are shown in Table 1.

  Sample 1 was obtained by adding 10 wt% of photocatalytic apatite (Ti-CaHAP) having a particle size of 20 (μm) as a photocatalyst to polypropylene resin.

  Sample 2 was obtained by adding 3 wt% of photocatalytic apatite (Ti-CaHAP) having a particle size of 10 (μm) as a photocatalyst to polypropylene resin.

  Sample 3 has no photocatalyst added to the polypropylene resin.

  Sample 4 is obtained by adding 10 wt% of titanium oxide having a particle size of 0.007 (μm) to polypropylene resin.

  Sample 5 is obtained by adding 2 wt% of photocatalytic apatite (Ti-CaHAP) having a particle size of 20 (μm) as a photocatalyst to polypropylene resin.

Sample 6 was obtained by adding 10 wt% of photocatalytic apatite (Ti-CaHAP) having a particle size of 5 (μm) as a photocatalyst to polypropylene resin.
(3) Subsequently, six types of samples were shaped into the following shapes using this pellet using an injection molding machine (product name SG-50, manufactured by Sumitomo Machine Co., Ltd.). The injection molding conditions are a cylinder temperature of 190 ° C. and a mold temperature of 250 ° C. The shape of each sample is (width 12 mm × width 70 mm × thickness 3 mm).
<Evaluation test of photocatalytic activity>
In the evaluation test method, the sample 1 was placed in a closed container (500 cc), and 12 ml of aldehyde gas (CH3CHO) was placed in the container and left in a dark place for 1 hour. Thereafter, an ultraviolet ray irradiator (product name: Lumina Ace LA150-TX, manufactured by Hayashi Watch Industry Co., Ltd.) was used to continuously irradiate 1 mW ultraviolet ray. By irradiating with ultraviolet rays, aldehyde (CH3CHO) is decomposed into carbon dioxide and moisture by the photocatalyst. The amount of the decomposed carbon dioxide was measured using a chromatography (GL Science Co., Ltd., product name GC-390B) at an interval of 1 hour. Therefore, the greater the amount of carbon dioxide measured, the higher the activity of the photocatalyst. Subsequently, the remaining samples 2 to 6 were evaluated by the above evaluation method. The results are shown in Table 2.

  As a criterion for determining the decomposition ability, 0.1 (ppm / hour) or more per unit time was considered appropriate. This is an appropriate value for, for example, decomposing hand grease, tobacco tar, dust and the like adhering to the case, key top, etc. overnight, that is, by the next day. Referring to Table 2, it is found that Sample 1, Sample 2, and Sample 4 are suitable resins for the casing, key top, and the like.

Next, a choking evaluation test was performed on the samples 1 to 6.
<Evaluation test for choking>
The evaluation test method of choking was evaluated from the weight reduction rate due to weathering.
Specifically, samples 1 to 6 were placed in a dark place, and an ultraviolet irradiator (product name: Lumina Ace LA150-TX, manufactured by Hayashi Watch Industry Co., Ltd.) was used, and 10 mW of ultraviolet rays were continuously irradiated. The weight change at this time was measured at intervals of 100 hours. The results are shown in Table 3.

As an evaluation, the weight change of the product was evaluated with a limit of about 99.5%.
Therefore, samples 1, 2, 3, 5, and 6 are appropriate. Of these, sample 3 does not contain a photocatalyst resin, so there is no weight reduction.

  From the above two evaluation results, Sample 1 and Sample 2 having high photocatalytic activity and no choking are suitable for a photocatalytic apatite-containing resin casing, a photocatalytic apatite-containing resin key, and the like. Such a photocatalytic apatite-containing resin can be applied to input devices such as a mouse, an input pen, and a keyboard that are touched manually, in addition to an electronic device casing and a portable device casing.

  Subsequently, a key top using a photocatalyst-containing resin having a chemical structure in which a part of Ca of calcium hydroxyapatite is substituted with Ti will be described.

  FIG. 1 shows a configuration of a key top according to this embodiment, and FIG. 2 is a cross-sectional view taken along line AA of FIG. 1 is a key switch, 2 is a key top, 3 is a key top member, 4 is a notation of letters, symbols, designs, etc., 5 is a concave portion of the key top member, and 6 is a mixture of antibacterial agents.

  Each key switch 1 has a unique meaning such as letters, numbers, symbols, designs, and the like. When the key switch 1 is pressed, it is detected at a contact (not shown) and a signal of that meaning is notified to the outside. These letters, numbers, symbols, symbols, and the like are displayed on the key top 2. Specifically, the key top 2 is generally composed of a key top member 3 and a notation 4. The key top member 3 is formed with a concave portion 5 in the shape of a groove in which letters, numbers, symbols, designs, and the like are formed on the top and side portions. A notation 4 is provided in the concave portion 5. The notation 4 in FIG. 1 is the number 1, for example. The key top member 3 is a resin, specifically, an ABS resin. The material of the notation 4 is an antibacterial agent mixture 6 made of a photocatalyst having a chemical structure in which a part of Ca of calcium hydroxyapatite made of an antibacterial agent and a resin is substituted with Ti and a resin.

Next, a key top manufacturing method will be described.
First, the notation 4 was molded using an injection molding machine (trade name Cycap, manufactured by Sumitomo Heavy Industries, Ltd.). This injection molding machine is generally composed of a supply unit, a member mixing unit, a member heating unit, and an injection unit. The above-mentioned photocatalytic apatite (trade name Photocatalytic apatite PCAP-100 manufactured by Taihei Chemical Co., Ltd.) has an average particle diameter of 20 μm, ABS resin (trade name VD-200 manufactured by UMG Co., Ltd.), and black pigment (product manufactured by Clariant Japan Co., Ltd.). Name Sanodal Deep Black MLW). The black pigment is a coloring of the notation and facilitates the color identification of the key top member 2. In the member mixing portion, 85% by weight of ABS resin, 10% by weight of photocatalytic apatite and 5% by weight of black pigment were uniformly mixed. Next, it is heated and melted in the member heating section. Subsequently, the melted antibacterial agent mixture 6 is injected from the injection portion into the mold. The cavity portion of this mold is formed in the same shape as the desired notation body 4 in advance. Therefore, a photocatalytic apatite-containing resin is formed as the notation 4.

  Next, the key top member 2 is molded in the same manner that the notation 4 is molded. A mold having a cavity part in which the key top member 2 is formed is prepared. Then, a material, specifically, an antibacterial mixture 6 composed of 80% by weight of ABS resin and 20% by weight of photocatalytic apatite is injected into the mold from the injection part by the same manufacturing method. Therefore, the key top member 2 made of a photocatalytic apatite-containing resin is formed. The notation 4 described above is fitted into the concave portion 5 of the key top member 2.

In the above embodiment, the photocatalytic apatite-containing resin is used for both the key top member 2 and the notation 4. However, when at least one of the key top member 2 and the notation 4 is provided with a photocatalyst-containing resin having a chemical structure in which a part of Ca of calcium hydroxyapatite is substituted with Ti, an antibacterial effect can be obtained.
<Second embodiment>
The first embodiment is a method of fitting the notation body 4 and the key top member 2 together.
However, the concave portion of the key top member may be filled with a photocatalyst-containing resin having a chemical structure in which part of Ca in the paste-like calcium hydroxyapatite is substituted with Ti, and may be solidified by heating and drying.

The block diagram of the key top which concerns on this embodiment, AA sectional view of FIG. It is a surface chemical structure figure of Ti-CaHAP.

Explanation of symbols

1 key switch,
2 key tops,
3 Key top material,
4 Notation,
5 concave parts,
6 Antibacterial agent mixture

Claims (3)

A step of directly kneading a photocatalyst having a chemical structure in which a part of Ca of calcium hydroxyapatite is substituted with Ti and a resin material to produce a resin composition;
Heating and melting the resin composition and injecting;
A method for producing a resin molded product comprising: The method for producing a resin molded product according to claim 1, wherein the content of the photocatalyst is 3 wt% to 10 wt%. The method for producing a resin molded product according to claim 1 or 2, wherein the photocatalyst has an average particle size of 10 to 20 µm .

Images