JP2008137732A - Toothed belt made of thermoplastic polyurethane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toothed belt made of thermoplastic polyurethane restraining discoloration caused by light absorption while preventing propagation of bacteria and growth of mildew by adding the appropriate amounts of an antimicrobial agent and a mildewproofing agent. <P>SOLUTION: The toothed belt 1 has a plurality of tooth parts arranged at predetermined intervals along a longitudinal direction, a back part, and core wires embedded in the plurality of tooth parts or the back part. The plurality of tooth parts and the back part are formed of thermoplastic polyurethane elastomer as a base material. The antimicrobial agent containing silver as a main component, and the mildewproofing agent containing thiabenzole as a main component, are added to the thermoplastic polyurethane forming the tooth parts and the back part. As to the compounding amounts, the antimicrobial agent is 0.6-1.0 pts.mass, and the mildewproofing agent is 0.15-0.25 pts.mass to 100 pts.mass of thermoplastic polyurethane. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toothed belt made of thermoplastic polyurethane having antibacterial and antifungal properties.

  Conventionally, belts based on a thermoplastic resin such as thermoplastic polyurethane have been widely used as belts used for transporting foods. Furthermore, in such a belt, in order to suppress the growth of bacteria and the growth of fungi on the conveyance surface, a material obtained by adding an antibacterial agent or a fungicide to a thermoplastic resin as a base material is known. For example, Patent Document 1 discloses an antibacterial / antifungal belt in which an antibacterial agent mainly composed of bis (2-pyridylthio-1-oxide) zinc is added to a resin such as polyurethane.

JP-A-11-29212

  However, since commonly used antibacterial agents and fungicides absorb light and cause discoloration of the belt, inevitably, the more the antibacterial agent and fungicides are added to the resin, the more light is added. Absorbs more and discolors the belt. In conventional antibacterial / antifungal belts, many antibacterial agents and fungicides are added unnecessarily, and there is a problem that the belt is severely discolored at an early stage after the start of use. Therefore, it is preferable that the antibacterial agent and the antifungal agent are blended in the minimum amount necessary for exhibiting sufficient antibacterial and antifungal properties.

  An object of the present invention is to provide a thermoplastic polyurethane tooth which can suppress discoloration while preventing the growth of bacteria and the growth of fungi by adding appropriate amounts of antibacterial and fungicidal agents to the belt base material. It is to provide an attached belt.

Means for Solving the Problems and Effects of the Invention

The toothed belt made of thermoplastic polyurethane according to the first invention has a plurality of tooth portions arranged at predetermined intervals along the longitudinal direction, a back portion, and the plurality of tooth portions or a core wire embedded in the back portion. Further, the plurality of tooth portions and the back portion are thermoplastic polyurethane toothed belts based on a thermoplastic polyurethane elastomer,
An antibacterial agent mainly composed of silver and an antifungal agent mainly composed of thiabenzol are added to the thermoplastic polyurethane forming the tooth part and the back part, and 100 parts by mass of the thermoplastic polyurethane, The antibacterial agent is blended in an amount of 0.6 to 1.0 part by mass, and the antifungal agent is blended in an amount of 0.15 to 0.25 part by mass.

  In this thermoplastic polyurethane toothed belt, a silver-based antibacterial agent and a thiabenzole-based antifungal agent are added to the thermoplastic polyurethane that forms a plurality of teeth and back portions, and the blending amount thereof is The antibacterial agent is 0.6 to 1.0 part by mass and the fungicide is 0.15 to 0.25 part by mass with respect to 100 parts by mass of the thermoplastic polyurethane. This prevents bacterial growth and fungal growth, and also suppresses discoloration of the belt due to light absorption.

  Embodiments of the present invention will be described. This embodiment is an example in which the present invention is applied to a toothed belt for conveyance used for conveyance of foods.

  FIG. 1 is a partially enlarged perspective view of the toothed belt of the present embodiment. As shown in FIG. 1, the toothed belt 1 includes a plurality of tooth portions 2 disposed at predetermined intervals along the belt longitudinal direction, a back portion 3 disposed opposite to the plurality of tooth portions 2, and a plurality of tooth portions 2. A core wire 4 embedded in the tooth portion 2 or the back portion 3 and a canvas 5 covering the plurality of tooth portions 2 are provided. FIG. 1 shows a toothed belt 1 in which a core wire 4 is embedded in the back portion 3 as an example.

  Both the plurality of tooth portions 2 and the back portion 3 are made of a thermoplastic polyurethane elastomer as a base material. As an isocyanate compound for producing this thermoplastic polyurethane, toluene diisocyanate, methylene diisocyanate, or the like is used. As the polyol, polytetramethylene glycol, adipate-based polyol, polycaprolactone-based polyol, or the like is used.

  Further, an antibacterial agent mainly composed of silver and an antifungal agent mainly composed of thiabenzol are added to this thermoplastic polyurethane, and the surface of the back 3 (conveying surface: lower side in FIG. 1) Surface) antibacterial and antifungal properties are enhanced. Here, the blending amount of the antibacterial agent and the antifungal agent exhibits sufficient antibacterial and antifungal properties, and the discoloration of the belt 1 caused by absorption of light by the antibacterial agent and the antifungal agent is suppressed as much as possible. Is set to an appropriate amount. Specifically, 0.6 to 1.0 parts by mass of an antibacterial agent and 0.15 to 0.25 parts by mass of an antifungal agent are blended with 100 parts by mass of thermoplastic polyurethane.

  The core wire 4 is made of polyarylate fiber, glass fiber, polyester fiber, aramid fiber or the like. The core 4 is embedded in a plurality of teeth 2 or backs 3 made of a thermoplastic polyurethane elastomer as a base material, and extends along the longitudinal direction of the belt 1 (perpendicular to the plane of FIG. 1). ing.

  As the canvas 5 covering the tooth portion 2, 6 nylon, 66 nylon, polyester, aramid fiber, etc., which are used alone or in combination can be used. Further, the warp (belt width direction) and weft (belt length direction) configuration of the canvas 5 is also the filament yarn or spun yarn of the fiber, and the woven configuration may be any of plain fabric, twill fabric, and satin fabric. In addition, it is preferable to use partly the stretched wooly nylon yarn, urethane elastic yarn, or a mixed twist of urethane elastic yarn and nylon.

  As described above, in the thermoplastic polyurethane toothed belt 1 of this embodiment, a silver-based antibacterial agent and a thiabenzol-based antifungal agent are added to the thermoplastic polyurethane forming the plurality of tooth portions 2 and the back portion 3. And are blended. Furthermore, the compounding quantity is 0.6-1.0 mass part for an antibacterial agent, and 0.15-0.25 mass part for antifungal agents with respect to 100 mass parts for thermoplastic polyurethane. This prevents the growth of bacteria and the growth of fungi on the conveying surface on which foods are placed, and also suppresses discoloration of the belt 1 due to the absorption of light by the antibacterial agent and the fungicide.

  Next, as a specific example of the present invention, an antibacterial agent and an antifungal agent were blended in the thermoplastic polyurethane in the blending amounts described above to prepare a sample. And the effect of this invention was verified compared with the sample (comparative example) in which the antibacterial agent and the antifungal agent were not mix | blended about the antibacterial property, mold resistance, and discoloration degree of the sample of this Example.

(Test sample)
In both Examples and Comparative Examples, samples were prepared using methylene diisocyanate as an isocyanate for producing a thermoplastic polyurethane resin as a base material, and using polybutylene adipate as a polyol. Samples of Examples (Examples 1 to 3) are mainly composed of the above-mentioned thermoplastic polyurethane, an antibacterial agent mainly composed of silver (Bioside TB-B10K, manufactured by Taisho Technos Laboratory Co., Ltd.), and thiabenzol. The antifungal agent (Bioside R-TZ, manufactured by Taisho Technos Laboratory Co., Ltd.) as an ingredient is blended in the blending amount shown in Table 1 (unit: antibacterial agent or antifungal agent part by mass relative to 100 parts by mass of thermoplastic polyurethane). And produced. On the other hand, an antibacterial agent and a fungicide were not blended in the sample of the comparative example.

(Antimicrobial test)
The antibacterial test was conducted in accordance with JIS Z 2801: 2000 antibacterial processed product-antibacterial test method, and verified that the samples of the examples had sufficient antibacterial effect. The specific test method is as follows.

1) Test strains The test strains used in this test are as follows.
Escherichia coli NBRC 3972
Staphylococcus aureus NBRC 12732

2) Calculation of antibacterial activity value and determination of antibacterial effect The antibacterial activity value R is calculated from the following equation.
R = log (B / C)
Here, R: antibacterial activity value, B: average value of viable bacteria after 24 hours of unprocessed test sample (pieces), C: average value of viable cell counts of 24 hours after antibacterial processed test samples (pieces) It is. That is, B corresponds to the number of viable bacteria after 24 hours of the comparative sample, and C corresponds to the number of viable bacteria after 24 hours of the example sample. When the antibacterial activity value R calculated from the above formula is larger than 2, it is determined that there is an antibacterial effect.

  The results of the above antibacterial test are shown in Table 2.

  As shown in Table 2, in both cases of Escherichia coli and Staphylococcus aureus, the number of viable bacteria after 24 hours was less than 10 in the samples of Examples 1 to 3, and the antibacterial activity value R was larger than 2. ing. This proved that Examples 1 to 3 have a sufficient antibacterial effect.

(Mold resistance test)
The mold resistance test was performed in accordance with the test of plastic products of JIS Z 2911: 2000 Annex 1 (normative), and it was verified that the samples of the examples had sufficient mold resistance. The specific test method is as follows.

1) Test strains The test strains used in this test are as follows.
Aspergillus niger van Tidghem NBRC 6431
Penicillium funiculosum Thom (blue mold) IAM 7013
Paecilomyces variotii Bainier IAM 5001
Gliocladium virens Miller, Giddens & Foster NBRC 6355
Chaetomium globosum Kunze ex Fries NBRC 6347

2) Test method
JIS Z 2911 defines two methods (Method A and Method B) as test methods. Method A uses an inorganic salt agar medium as a nutrient source, and evaluates the extent to which mold damages the material components. Method B is an inorganic salt agar medium with glucose added to evaluate mold resistance in an environment where mold tends to occur. Since these details are described in JIS Z 2911, they are omitted here.

3) Criteria In method A and method B, the growth of mold in the sample is observed, and the mold resistance is evaluated according to the following criteria.
(Observation results in Method A)
0: No mold growth was observed with the naked eye or under a microscope.
1: The growth of mold is not observed with the naked eye, but is confirmed under a microscope.
2: The growth of mycelia is observed with the naked eye, but the area of the growth part does not exceed 25% of the total area of the sample.
3: Mycelial growth is observed with the naked eye. The area of the growth part exceeds 25% of the total area of the sample.
(A method criteria)
And the observation result is
0: The material is not a nutrient source for mold.
Case 1: The material contains or is contaminated with nutrients that cause the mold to grow slightly.
In the case of 2 or 3: The material is not resistant to mold and contains a nutrient source suitable for mold growth.
Is determined.

(Observation results in Method B)
0: No mold growth was observed with the naked eye or under a microscope. If a growth inhibition zone is observed around the sample, the width is described in parentheses in mm.
1: The growth of mold is not recognized with the naked eye, but is confirmed under a microscope.
2: The growth of mycelium is slight, and the area of the growth part does not exceed 25% of the total area of the sample.
3: The growth of mycelium is moderate and the area of the growth part is 25-50% of the total area of the sample
4: Mycelium grows well, the area of the growth part is 50-100% of the total area of the sample
5: Mycelia grow vigorously and cover the front of the sample.
(B method judgment criteria)
The above observation results
0: Strong mold growth inhibitory effect 0 (with inhibition zone): Strong mold growth inhibitory effect 1 due to diffusible substance 1: Incomplete mold growth inhibitory effect 2-5: Gradual mold The growth effect is reduced and disappears completely.
Is determined.

  Table 3 shows the results of observing the degree of mold growth of the samples after the lapse of 4 weeks from the start of the tests in the above mold resistance test.

  As shown in Table 3, in Examples 1 to 3, the observation results are 0 for both the A method and the B method. That is, no mold growth was observed with the naked eye or under a microscope. Thereby, it was demonstrated that the sample of an Example has sufficient mold resistance (mold prevention).

(Discoloration test results)
The discoloration test was performed according to JIS K 6266. Specifically, the samples of Examples 1 to 3 and the comparative example were irradiated with light using an ultraviolet carbon arc lamp as a light source for 7 days under the condition of an atmospheric temperature of 63 ± 3 ° C., and the color difference measuring device was used as a reference. The color difference ΔE * from the body was measured. The results are shown in Table 4.

  As shown in Table 4, the color difference between Examples 1 to 3 and the comparative example is the same, and the discoloration in the sample of the example remains the same as the discoloration of the comparative example in which the antibacterial agent and the antifungal agent are not blended. I understand that.

  By the above test, 0.6 to 1.0 parts by mass of the antibacterial agent and 0.15 to 0.25 parts by mass of the antifungal agent are blended with 100 parts by mass of the thermoplastic polyurethane, so that the bacteria propagate. It has been demonstrated that the growth of fungi is reliably prevented, and that the discoloration associated with the absorption of light by the antibacterial and antifungal agents is suppressed to the same extent as when they are not added.

It is a partially expanded perspective view of the toothed belt of this embodiment.

Explanation of symbols

1 Toothed belt 2 Tooth part 3 Back part 4 Core wire

Claims (1)

A plurality of tooth portions arranged at predetermined intervals along the longitudinal direction; a back portion; and the plurality of tooth portions or a core wire embedded in the back portion; and the plurality of tooth portions and the back portion. A thermoplastic polyurethane toothed belt based on a thermoplastic polyurethane elastomer,
An antibacterial agent mainly composed of silver and a fungicidal agent mainly composed of thiabenzol are added to the thermoplastic polyurethane forming the tooth part and the back part,
The thermoplastic polyurethane, wherein 0.6 to 1.0 parts by mass of the antibacterial agent and 0.15 to 0.25 parts by mass of the antifungal agent are blended with respect to 100 parts by mass of the thermoplastic polyurethane. Toothed belt.

Images