JP2016026250A - Composite material, antibacterial article comprising composite material, method for producing composite material and method for producing antibacterial article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material which prevents occurrence of environmental problems such as global warming and air pollution, allows saving of oil resources, and can show excellent antibacterial properties.SOLUTION: A composite material comprises bamboo and shellac resin, and a compounding ratio between the bamboo and the shellac resin is: bamboo:shellac resin=80:20-30:70.SELECTED DRAWING: None

Description

  The present invention relates to a composite material, an antibacterial article including the composite material, a method for manufacturing the composite material, and a method for manufacturing the antibacterial article. More specifically, the present invention relates to a composite material capable of exhibiting excellent antibacterial properties, an antibacterial article including the composite material, a method for producing the composite material, and a method for producing the antibacterial article.

  There are a wide variety of pathogens such as bacteria and viruses around us. These pathogens can enter the body through various routes such as skin, mucous membranes, oral cavity, and wounds, and can cause inflammation, fever, convulsions, paralysis, etc. in various parts of the body. Whether an infectious disease develops when a pathogen enters the body depends largely on the infectivity of the pathogen itself and how effective the immune function of the organism is in preventing the growth of the pathogen. To do. For example, infants that have just been born do not have sufficient immune function. In addition, coldness, exhaustion of physical strength, stress, and aging decrease immune function. Therefore, pathogens can be a sufficient threat in hospitals where many people with reduced immune functions gather.

  Such nosocomial infections are often used in various media, and recently, health-consciousness has increased, and much attention has been paid to the prevention of infectious diseases. Along with this, many antibacterial articles have been developed. By the way, even if it is an antibacterial article, the field utilized is wide. For example, antibacterial articles are not only those that can directly lead to infectious diseases such as food poisoning, pneumonia, and skin diseases, such as cooking utensils, watering utensils, and clothing, but also infections. There are small stationery and fancy goods that are directly connected.

  Many antibacterial articles contain an antibacterial component that exhibits an antibacterial effect. However, in general, antibacterial components are expensive compared to general-purpose materials. Therefore, an antibacterial component that is cheaper and can be stably supplied in large quantities is demanded. From such a viewpoint, bamboo is an inexpensive and excellent antibacterial material. Bamboo has a lot of nutrients in the body, especially in the early stages of growth, and is an antibacterial component mainly composed of 2,6-dimethoxy-1,4-benzoquinone, parabenzoquinone, etc. to protect itself from mold and bacteria Secrete. Bamboo exhibits high tensile strength and compressive strength, and excellent wear resistance, impact resistance, etc., particularly in the fiber direction, as compared to other wood materials.

  However, bamboo has a cylindrical shape, and it is difficult to process into a complicated shape by cutting or cutting. Therefore, a technique is known in which bamboo material pulverized into a powder is molded with a binder component made of resin. For example, in Patent Document 1, a powder obtained by pulverizing a fine powder of 10 to 200 microns using a defibrated bamboo fiber chopped strand obtained by dissociating cellulose and hemicellulose forming cell walls from lignin, starch, processed starch, etc. Antibacterial and deodorizing raw bamboo powder molded into arbitrary blocks with natural pastes and processed pastes such as CMC (carboxymethylcellulose), PVA (polyvinyl alcohol), PVAC (polyvinyl acetate), acrylic and epoxy. Techniques relating to deodorants are disclosed.

  By the way, in recent years, environmental problems are one of the most important themes that companies must tackle regardless of the type of business. One example is the disposal of waste such as plastic products (including those made entirely of plastic, including those in which some composite materials are made of plastic). As a method for treating plastic product waste, incineration treatment and landfill treatment are generally used. In the landfill process, carbon dioxide is not generated, and although concerns such as environmental hormones remain, the emission of harmful substances is suppressed compared to the incineration process. However, landfill processing requires land to be landfilled by the amount of waste. Then, it is impossible to process all plastic waste in this way.

  In contrast, the incineration process can process a large amount of waste in a limited facility. However, the high amount of heat, carbon dioxide, and other harmful substances emitted during incineration can cause environmental problems such as global warming and air pollution, as well as the economic burden of construction and maintenance of incineration facilities. ing. The problem of global warming associated with carbon dioxide emissions may cause serious situations on a global scale, such as water shortages, food depletion, desertification, and expansion of habitats for pathogenic bacteria and pests.

  Focusing on the emission of carbon dioxide, for example, disclosed in Patent Document 1, starch and processed starch and CMC as green bamboo powder and natural paste, even if incinerated, The amount of carbon dioxide originally taken from the atmosphere (carbon neutral). Therefore, the concentration of carbon dioxide in the atmosphere is not increased. Such a material is “a renewable, organic organic resource excluding fossil resources” and is called a biomass material. On the other hand, other pastes such as PVA, PVAC, acrylic, and epoxy contain petroleum-derived components. Therefore, when the articles disclosed in Patent Document 1 using these pastes and articles in other fields obtained by applying the technology are discarded and incinerated, the concentration of carbon dioxide in the atmosphere is To increase.

  Petroleum is not only a raw material for plastics but also an extremely important energy source. However, oil has limited reserves. Therefore, if you continue to use oil, it will eventually run out. On the other hand, biomass materials have the advantage of being reproducible as well as carbon neutral. Therefore, taking advantage of reproducibility, there is an urgent need to replace petroleum with biomass materials.

JP 2013-6403 A

  As described above, providing an antibacterial article using bamboo as a biomass material and a binding component has great significance from the viewpoint of preventive medicine as well as from the viewpoint of reducing environmental burden and saving resources. By the way, the binding component used with bamboo is not anything that can be used as long as it is a biomass material. The starch, processed starch, and CMC disclosed as a binding component in Patent Document 1 have insufficient water resistance. Therefore, it is inappropriate as a use of cooking utensils, tableware, and water-related items.

  On the other hand, a water-resistant binding component cannot be easily dissolved in water and used. Therefore, when using a water-resistant binder component, it is necessary to manufacture a molded article mainly in a state of being dissolved by powder, an organic solvent, or heated and melted. However, the binder component is not uniformly mixed with bamboo powder in the powder state. For this reason, in the case of performing drilling with a drill or cutting with a saw on an article after molding, the suitability (post-workability) and mechanical strength tend to decrease. Further, when the binder component is dissolved in an organic solvent, it is necessary to dry the organic solvent for molding. In addition, if the generated organic solvent is released into the atmosphere, there is a risk of air pollution and the like, so a separate process is required. Furthermore, the binder component which consists of many biomass materials has thermoplasticity. For this reason, when the material is heated and melted, the low melting point material has a low heat resistance instead of requiring less heat energy to be melted. Further, a material having a high melting point requires a large amount of heat energy for melting.

  The present invention has been made in view of such conventional problems, does not cause environmental problems such as global warming and air pollution, and from among the biomass materials that enable saving of petroleum resources, It is an object of the present invention to provide a composite material that can exhibit excellent antibacterial properties and a method for producing the composite material by using bamboo material and shellac resin. Another object of the present invention is to provide an antibacterial article that exhibits excellent antibacterial properties and has both sufficiently practical post-processing suitability and mechanical strength, and a method for producing the antibacterial article.

  As a result of intensive studies to solve the above problems, the present inventors use bamboo as an antibacterial material, and use a shellac resin that is a biomass material and has thermosetting properties as a binding component. And it discovered that the composite material which can show favorable antibacterial property was obtained by making the mixture ratio of a bamboo and shellac resin into a specific range, and completed this invention. In addition, the present inventors have found that an antibacterial article obtained by using such a composite material has both post-processing suitability and mechanical strength, and completes the present invention.

  That is, the composite material of the present invention, the antibacterial article including the composite material, the method for producing the composite material, and the method for producing the antibacterial article that solve the above problems mainly include the following configurations.

  (1) A composite material including bamboo and shellac resin, wherein a blending ratio of the bamboo and the shellac resin is bamboo: shellac resin = 80: 20 to 30:70.

  According to such a configuration, the composite material includes bamboo and shellac resin in a ratio of 80:20 to 30:70. Such a composite material does not cause environmental problems such as global warming and air pollution, and can save oil resources. Further, when an antibacterial article is produced by, for example, thermoforming, the obtained antibacterial article not only exhibits excellent antibacterial properties, but also has sufficiently practical post-processing suitability and mechanical strength.

  (2) The composite material according to (1), wherein the bamboo is powdery or fibrous and is dispersed in the shellac resin.

  According to such a configuration, bamboo is dispersed in the shellac resin. For example, when an antibacterial article is produced by thermoforming such a composite material, the resulting antibacterial article is more suitable for post-processing than an antibacterial article obtained by thermoforming a composite material having non-dispersibility. And mechanical strength variation is smaller.

  (3) An antibacterial article obtained by thermoforming the composite material according to (1) or (2).

  According to such a configuration, the antibacterial article does not cause environmental problems such as global warming and air pollution, and can save petroleum resources. Moreover, the antibacterial article not only exhibits excellent antibacterial properties, but also has sufficiently practical post-processing suitability and mechanical strength.

  (4) The antibacterial article according to (3), wherein the composite material is in a powder form or a chip form.

  According to such a configuration, the antibacterial article is obtained by heat-molding a composite material once processed into a powder form or a chip form. Therefore, the antibacterial article can be processed into various shapes by thermoforming.

  (5) The manufacturing method of a composite material including the mixing process which mixes bamboo and shellac resin so that it may become bamboo: shellac resin = 80: 20-30: 70 at 70-120 degree.

  According to such a structure, bamboo is mixed with shellac resin melted at 70 to 120 ° so that bamboo: shellac resin = 80: 20 to 30:70. The resulting composite material not only exhibits excellent antibacterial properties, but also has sufficiently practical post-processing suitability and mechanical strength.

  (6) The method for producing a composite material according to (5), including a primary pulverization step of pulverizing the bamboo into a powder or fiber before the mixing step.

  According to such a configuration, bamboo pulverized into powder or fiber is used in the mixing step. Therefore, bamboo is more uniformly dispersed in the shellac resin. As a result, the antibacterial article using the obtained composite material has less variations in post-processing suitability and mechanical strength compared to the antibacterial article using the composite material with non-uniform dispersibility.

  (7) A secondary pulverization step of pulverizing the composite material obtained by the method for producing a composite material according to (5) or (6) into a powder or a chip, and a thermoforming step of thermoforming the obtained pulverized product A method for producing an antibacterial article.

  According to such a configuration, the obtained composite material is once pulverized into a powder form or a chip form, and then heat-molded. Therefore, the antibacterial article can be processed into various shapes by thermoforming.

  (8) The method for producing an antibacterial article according to (7), including a thermosetting treatment step of performing thermosetting treatment of the shellac resin simultaneously with the thermoforming step or after the thermoforming step.

  According to such a configuration, the antibacterial article containing the shellac resin can be further improved in heat resistance, water resistance, chemical resistance, wear resistance, mechanical strength, and the like. In addition, the thermosetting process may be performed simultaneously with the thermoforming process. In this case, the thermoforming process also serves as a thermosetting process. On the other hand, the thermosetting treatment step may be performed after the heat forming step.

  ADVANTAGE OF THE INVENTION According to this invention, the composite material which can exhibit the outstanding antimicrobial property, and the manufacturing method of this composite material can be provided. In addition, according to the present invention, it is possible to provide an antibacterial article that exhibits excellent antibacterial properties and has sufficient practical post-processing suitability and mechanical strength, and a method for producing the antibacterial article.

FIG. 1 is a schematic graph for explaining the relationship between the blending ratio of bamboo and shellac resin and antibacterial property or moldability / processability.

<Composite material>
The composite material of one embodiment of the present invention includes bamboo and shellac resin. The blending ratio of bamboo and shellac resin is bamboo: shellac resin = 80: 20-30: 70. First, the concept of the present embodiment will be described before specifically describing the present embodiment.

  Bamboo used in the present embodiment includes lignin that functions as a binding component, 2,6-dimethoxy-1,4-benzoquinone, parabenzoquinone, and the like having antibacterial action. For example, when such bamboo is pulverized into powder, charged in a mold, and pressure-molded, a molded article formed into a shape corresponding to the mold is obtained. Only bamboo is present on the surface of the molded article. Therefore, the antibacterial effect of the antibacterial property of bamboo is reflected as it is. Further, post-processing suitability and mechanical strength of the molded article are considered to depend on the binding force. Therefore, the effect of binding components such as lignin contained in bamboo is directly reflected in post-processing suitability and mechanical strength.

  In contrast, in a molded article obtained from a composite of bamboo pulverized into powder and shellac resin, not only bamboo but shellac resin is exposed on the surface of the molded article. Roughly speaking, the antibacterial properties of such molded articles are the antibacterial action of bamboo and the antibacterial action of shellac resin, respectively, in the area where bamboo is exposed and the area where shellac resin is exposed. It is inferred that it will be an appropriate amount. In addition, post-processing suitability and mechanical strength of molded articles are presumed to depend on the properties of both bamboo and shellac resins.

  Here, as an antibacterial action, the antibacterial action of bamboo is superior to the antibacterial action of shellac resin. Therefore, when the blending ratio of shellac resin with respect to bamboo increases, the exposed area of shellac resin increases, and the antibacterial property of the molded article is the best when it consists only of bamboo, and the blending ratio of shellac resin increases. It is expected to decline with time.

  On the other hand, post-processing suitability and mechanical strength of molded articles are poor in the case of bamboo alone, because the absolute amount of the binder component is insufficient. And shellac resin acts as a binding component. Therefore, the post-processing suitability and mechanical strength of the molded article are improved as the ratio of the shellac resin to the bamboo increases, and then the characteristic that the shellac resin is hard and somewhat brittle is expressed and changes in a complicated manner.

  FIG. 1 is a schematic graph for explaining the relationship between the blending ratio of bamboo and shellac resin and antibacterial properties or moldability / processability. Fig. 1 shows the antibacterial property on the horizontal axis with the blending ratio (bamboo / shellac resin mass ratio) of bamboo and shellac resin contained in the molded article obtained by pressure molding based on the above prediction. The relationship is shown with the vertical axis, post-processing suitability and mechanical strength on the right vertical axis. In Table 1, Graph 1 represents the relationship between the blending ratio of bamboo and shellac resin and antibacterial properties, and Graph 2 represents the relationship between the blending ratio of bamboo and shellac resin, post-processing suitability, and mechanical strength. In addition, FIG. 1 is a schematic graph until it gets tired. Therefore, the slope of the curve in FIG. 1 does not necessarily accurately reflect the actual situation.

  As shown in FIG. 1, a molded article obtained by pressure molding only powdered bamboo exhibits the most excellent antibacterial properties. On the other hand, this molded article has poor post-processing suitability and mechanical strength, and causes practical problems. Therefore, when a composite material of bamboo and shellac resin is used and the post-processing suitability and mechanical strength are observed, the post-processing suitability and mechanical strength are improved as the blending ratio of the shellac resin increases. However, if the proportion of shellac resin is excessively increased, post-processing suitability and mechanical strength begin to decrease due to an increase in the proportion of shellac resin. On the other hand, the antibacterial property maintains a high effect for a while even if the shellac resin exceeds the blending ratio in which post-processing suitability and mechanical strength are less than the practical level. As a result, as a result, the region where the effect of the antibacterial article obtained from the composite material of the present embodiment is maintained is equal to the region where post-processing suitability and mechanical strength exceeding the practical level can be obtained.

  Shellac resin is brittle compared to general-purpose resin materials. Therefore, if a general-purpose tough resin material is used as a binder component, a region where post-processing suitability and mechanical strength exceeding a practical level can be obtained may be expanded. However, most of general-purpose resin materials contain petroleum-derived components. Therefore, such a resin material cannot solve the problems of the present embodiment (particularly environmental problems such as global warming and air pollution).

  Returning to the description of the present embodiment, based on the above reasons, in the composite material of the present embodiment, the blending ratio of bamboo and shellac resin is bamboo: shellac resin = 80: 20 to 30:70. The blending ratio of bamboo and shellac resin is more preferably 75:25 to 40:60. When the blending ratio of bamboo and shellac resin is within the above range, the antibacterial article obtained using the composite material has not only antibacterial properties but also practicality in post-processing suitability and mechanical strength. When the blending ratio of bamboo exceeds 80%, post-processing suitability and mechanical strength tend to decrease. On the other hand, when the blending ratio of bamboo is less than 30%, the antibacterial article tends to deteriorate in post-processing suitability and mechanical strength. Moreover, when the compounding ratio of bamboo is less than 10%, the antibacterial article tends to greatly decrease the antibacterial property.

  Next, raw materials for the composite material (bamboo and shellac resin) will be described. Bamboo (bamboo material) is a wooden material belonging to bamboo and exhibits antibacterial properties. Bamboo is a biomass material that is defined as “renewable, biologically derived organic resources excluding fossil resources”.

  Bamboo contains antibacterial components such as 2,6-dimethoxy-1,4-benzoquinone and parabenzoquinone. These antibacterial components exhibit a strong antibacterial action. To give an example, the antibacterial activity value of a molded product obtained by pressure-molding crushed bamboo can be a numerical value of 6.7 or more based on the conditions and results of the antibacterial test in the examples described later. . In this embodiment, the antibacterial activity value is defined by JIS Z 2801, and is calculated by the following calculation formula: “the logarithm of the number of viable bacteria after inoculating and culturing bacteria in the antibacterial processed product and the unprocessed product. It is a value indicating a difference.

R = (Ut-Uo)-(At-Uo)
Where R is the antibacterial activity value, Uo is the logarithm of the number of viable bacteria immediately after inoculation of the unprocessed test piece, Ut is the logarithm of the number of viable bacteria 24 hours after the unprocessed test piece, and At is the antibacterial processed test piece Is a logarithmic value of the viable cell count after 24 hours.

  The antibacterial component is contained in a large amount especially in the green part of the bamboo surface. The composite material of this embodiment is not a case where only a special portion of bamboo (for example, a green portion of the bamboo surface) is used, but a case where powder obtained by uniformly crushing all portions of bamboo is used. However, a good effect can be obtained. More preferably, the composite material of the present embodiment is used so as to include a lot of green portions on the bamboo surface.

  The kind of bamboo is not particularly limited. As an example, the bamboo is a bamboo sword, a true bamboo, a light bamboo, a cocoon, or the like. Among these, Miso bamboo is preferred because it is easily available because it lives in various parts of Japan, is a large species, and exhibits high antibacterial effects.

  Bamboo can be pulverized into powder or fiber. The bamboo of this embodiment is preferably dispersed in a shellac resin, which will be described later, after being pulverized into powder or fiber. By using bamboo pulverized into a powder or fiber, the composite material can be used for, for example, thermoforming to produce an antibacterial article, resulting in variations in post-processing suitability and mechanical strength of the obtained antibacterial article. Compared with an antibacterial article obtained by heat-molding a composite material having non-uniform dispersibility, it becomes smaller.

  The method for crushing bamboo is not particularly limited. For example, bamboo can be pulverized into powder or fiber by passing it through a pulverizer that applies mechanical force such as cutting, compression, and cutting. In addition, the bamboo may be pulverized into a fiber by a blasting process or a steaming process. The size of bamboo pulverized into a powder is generally 2 mm or less, preferably 1 mm or less, more preferably 0.5 mm or less. In addition, the size of bamboo pulverized into fibers is generally such that the fiber diameter is 0.2 mm or less and the length is 10 mm or less, preferably 5 mm or less.

  On the other hand, shellac resin (shellac resin) is a resin obtained by refining a resinous substance secreted by a scale insect and several kinds of scale insects closely related thereto. Shellac resin is a biomass material. Shellac resin is rare as a biomass material and exhibits self-crosslinking properties at an appropriate heating temperature and heating time. Therefore, when the thermosetting treatment is performed under conditions where a crosslinking reaction occurs, heat resistance, water resistance, oil resistance, wear resistance, and the like can be improved.

  Shellac resin is mainly an esterified product of shellolic acid, aleuritic acid and jalaric acid. The esterified product has a heat softening temperature (a state in which a crosslinking reaction is not performed by heat curing treatment) of about 70 to 75 ° C. In addition, the shellac resin can be improved in heat resistance, water resistance, oil resistance, wear resistance and the like by performing a thermosetting treatment by heating at about 120 to 180 ° C. for an appropriate time. Therefore, when the composite material is used for an application that does not require a heat resistant temperature of 70 ° C. or higher or high water resistance, the antibacterial article can be obtained without performing a thermosetting treatment. On the other hand, when the composite material is used for an application that requires excellent heat resistance, water resistance, etc., it may be softened and then subjected to thermosetting at a high temperature. Thus, shellac resin can select a preferable processing method according to the use of a composite material. Details of such a heating method will be described later.

  As described above, according to the present embodiment, the composite material includes bamboo and shellac resin in a ratio of 80:20 to 30:70. For example, when an antibacterial article is produced by thermoforming such a composite material, the resulting antibacterial article not only exhibits excellent antibacterial properties, but also has sufficiently practical post-processing suitability and mechanical strength. Have both.

<Production method of composite material>
The manufacturing method of the composite material of one Embodiment of this invention includes the mixing process which mixes bamboo and shellac resin so that it may become bamboo: shellac resin = 80: 20-30: 70 at 70-120 degreeC. The bamboo and shellac resins used in this embodiment are the same as those described above in the embodiment of the composite material. Therefore, these descriptions are omitted as appropriate.

  As described above, the heat softening temperature of the shellac resin is about 70 to 75 ° C. Therefore, in the mixing step, when the shellac resin is heated to 70 to 120 ° C., more preferably 80 to 115 ° C., the shellac resin is softened without being subjected to a crosslinking reaction and is in a molten state. In such a molten shellac resin, bamboo is mixed in this mixing step so that bamboo: shellac resin = 80: 20 to 30:70. The mixed bamboo can be appropriately dispersed in the shellac resin in the molten state.

  Bamboo mixed with shellac resin is more likely to be uniformly mixed with shellac resin if it is pulverized in advance. Therefore, it is preferable that the manufacturing method of the composite material of this embodiment includes the primary grinding | pulverization process which grind | pulverizes bamboo into a powder form or a fiber form before a mixing process. Thereby, the bamboo is more uniformly dispersed in the shellac resin. As a result, the antibacterial article using the obtained composite material has less variations in post-processing suitability and mechanical strength than the antibacterial article using the composite material having non-uniform dispersibility.

  The method for performing the primary pulverization step and the mixing step is not particularly limited. As an example, as described above, the pulverization of bamboo may be performed by using a pulverizer that applies mechanical force, or by a blasting process or a steaming process. Moreover, mixing of bamboo and shellac resin can be implemented by using various kneading apparatuses such as a roll mill, a kneader, and a twin screw extruder. The mixing of the bamboo and the shellac resin is preferably carried out by melting the shellac resin and then adding the bamboo pulverized into a powder or fiber.

  The composite material obtained through the mixing step is then pressure-molded and processed into an antibacterial article.

<Method for producing antibacterial article>
The method for producing an antibacterial article according to an embodiment of the present invention includes a secondary pulverization step of pulverizing the composite material obtained through the mixing step into a powder form or a chip shape, and heating for thermoforming the obtained pulverized product. Includes a molding process.

  The secondary pulverization step is a step of pulverizing the composite material obtained through the mixing step into a powder form or a chip form. The method for pulverizing the composite material is not particularly limited. As an example, the composite material can be pulverized into powder or chips using various known pulverizers. The composite material pulverized into a powder form or a chip form can be processed into various shapes in the subsequent thermoforming process.

  The thermoforming step is a step of processing the pulverized composite material obtained in the secondary pulverization step into various shapes by thermoforming. The method for thermoforming the pulverized product is not particularly limited. For example, the heat molding may be performed by a method such as charging a pulverized product into a mold composed of a combination of a fixed mold and a movable mold and performing pressure molding.

  Here, the shellac resin is a rare thermosetting resin as a biomass material. Therefore, when a thermosetting treatment is performed, intermolecular crosslinking may occur due to an esterification reaction between a carboxyl group and a hydroxyl group of a component constituting the shellac resin. In the case of using a composite material having a high content ratio of shellac resin in consideration of the possibility that water produced by the esterification reaction causes hydrolysis of the ester and remains as bubbles of water vapor in the molded product. It is preferable to immediately remove water generated during the thermosetting treatment.

  It is preferable that such a shellac resin thermosetting treatment (thermosetting treatment step) is performed at the same time as or after the heating step. That is, when the heating temperature and the heating time in the thermoforming process are adjusted to satisfy the conditions for causing the thermosetting reaction of the shellac resin, the thermosetting process can be performed simultaneously with the thermoforming process. On the other hand, only the thermoforming process is performed in a temperature range where the shellac resin is sufficiently softened but does not cause a thermosetting reaction (for example, about 80 to 120 ° C.). Thermosetting treatment may be performed by raising the temperature to about 120 to 180 ° C. By performing the thermosetting treatment step, the shellac resin is cured, and the antibacterial article containing the shellac resin is further improved in heat resistance, water resistance, chemical resistance, wear resistance, mechanical strength, and the like.

  As mentioned above, according to the manufacturing method of the antibacterial article of this embodiment, the antibacterial article by which the above-mentioned composite material was processed into various shapes is obtained. The obtained antibacterial article not only exhibits excellent antibacterial properties, but also has sufficiently practical post-processing suitability and mechanical strength.

  Moreover, the obtained antimicrobial article is used for various uses. For example, antibacterial articles include tableware such as cups and bowls, bowls, dishes, cooking utensils such as rice scoops and cutting boards, knives patterns, pot patterns, bath utensils such as bath tubs, bath lids, and slats. It can be used for handrails, floor materials, wall materials, etc. of medical buildings. Among these, antibacterial articles exhibit not only excellent antibacterial properties but also sufficiently practical post-processing suitability and mechanical strength, so that these are strictly required fields (for example, handrails and floors of medical buildings). Even when used in materials, wall materials, etc., the requirements can be fully met.

  In the case of producing an antibacterial article having a surface that is in direct contact with food, such as tableware and cooking utensils, shellac resin is preferably the sixteenth from the viewpoint of food safety and hygiene. A purified shellac resin or white shellac resin listed in the revised Japanese Pharmacopoeia is preferable.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to these examples.

Example 1
-Preparation of composite material Bamboo (kind: Somune bamboo) was pulverized using a mechanical pulverizer (primary pulverization step). The obtained bamboo (bamboo powder) was passed through a 36 mesh (spread: 0.42 mm) sieve. First, using two rolls heated to 100 ° C., shellac resin (trade name: dry transparent white rack, manufactured by Nippon Shellac Industry Co., Ltd.) is heated and melted (mixing step), and the bamboo after sieving is bamboo: The mixture was mixed so that the shellac resin = 75: 25 (mass ratio) and kneaded for 10 minutes to obtain a thin plate-shaped composite material. Thereafter, the composite material was cooled to room temperature and pulverized using a pulverizer (Wonder Blender, Osaka Chemical Co., Ltd.) (secondary pulverization step) to obtain a composite material.

-Preparation of antibacterial article 36 g of the above composite material was charged in a mold that can be molded into a disk shape with a diameter of 100 mm (mixing process), and heated at a heating press of 140 (manufactured by Shinto Metal Industries Co., Ltd.) at a heating temperature of 140 An antibacterial article having a diameter of 100 mm and a thickness of about 4 mm was produced by pressure molding (heating molding process and thermosetting process) under conditions of ˜160 ° C., pressure 10 MPa, and heating time 15 minutes.

(Example 2)
A composite material and an antibacterial article were produced in the same manner as in Example 1 except that the blending ratio of bamboo and shellac resin was changed to bamboo: shellac resin = 50: 50.

(Comparative Example 1)
Except for using only bamboo without compounding shellac resin and performing pressure molding under the conditions of a heating temperature of 180 ° C., a pressure of 20 MPa, and a heating time of 5 minutes, the composite material and An antibacterial article was prepared.

(Comparative Example 2)
A composite material and an antibacterial article were produced in the same manner as in Example 1 except that the blending ratio of bamboo and shellac resin was changed to bamboo: shellac resin = 25: 75.

(Comparative Example 3)
The composite material and the composite material were prepared in the same manner as in Example 1 except that only shellac resin was used without blending bamboo, and pressure molding was performed under the conditions of a heating temperature of 140 ° C., a pressure of 0 MPa, and a heating time of 15 minutes. An antibacterial article was prepared.

  About each antibacterial article obtained in Examples 1-2 and Comparative Examples 1-3, antibacterial property, post-processability, and mechanical strength were evaluated with the following method.

(Antimicrobial test)
Each antibacterial article was cut into a square with a side of 50 mm to produce a test piece for antibacterial test, and an antibacterial test was conducted according to JIS Z2801. In addition, Escherichia coli NBRC3972 of Escherichia coli was used as the bacterial species, and the test bacterial solution was prepared by dilution of 1/50 NB. Table 1 shows the antibacterial activity value of the antibacterial article. In addition, if an antibacterial activity value is 2.0 or more, it can be judged that practical antibacterial property is shown.

(Post-processing suitability)
A commercially available tabletop drilling machine (EARTH MAN DP-200, manufactured by Takagi Corporation, drill diameter: 6.5 mm, rotation speed: about 2300 rpm, feed rate: about 60 mm / min) and tabletop band saw (EARTH MAN tabletop woodworking band saw RBS-10 Manufactured by Takagi Co., Ltd., blade width: 6.35 mm, number of ridges: 6 ridges / inch, thickness: 0.35 mm, blade speed: about 19 m / second) Opening and cutting were performed. The antibacterial article has a perforated surface and a cut surface (in the antibacterial article, the surface of the antibacterial article where the drill and blade blade first is the front surface and the opposite side is the back surface), and the following evaluations are made. Post-processing suitability was evaluated according to the criteria. The results are shown in Table 1.
(Evaluation criteria)
○: It was judged that the perforated surface and the cut surface were less rough and suitable for post-processing.
X: It was judged that the perforated surface and the cut surface were rough and were not suitable for post-processing.

(Mechanical strength)
Each antibacterial article (excluding the antibacterial articles of Comparative Example 1 and Comparative Example 3) was cut into a strip shape having a width of 10 mm and a length of 80 mm to obtain a test piece, and subjected to a bending load test under the following conditions. The mechanical strength (bending strength) was evaluated based on the maximum load until failure occurred. Table 1 shows the bending strength values. In addition, since the antibacterial article of Comparative Example 1 was easily broken at the stage of preparing the test piece, it was determined that the mechanical strength was extremely low without performing this evaluation. Moreover, since the antibacterial article of Comparative Example 3 had an antibacterial activity value of less than 2 in the antibacterial test, this evaluation was not performed.
Test type: 3-point bending Test speed: 1.5 mm / min

  Regarding the numerical value of mechanical strength (bending strength), for example, according to the materials of the Japan Plastic Industry Federation, the bending strength of polypropylene, which is a typical general-purpose plastic, is 41 to 55 MPa. On the other hand, as shown in Table 1, the antibacterial article of Comparative Example 2 had a bending strength of 35.3 MPa, which was slightly lower than that of polypropylene. In the present invention, the antibacterial article is advantageous in that it has a higher strength, and the application range is expanded. Therefore, in this evaluation, it was judged that what shows a mechanical strength larger than the antimicrobial article of the comparative example 2 was preferable. From this point, the antibacterial articles of Examples 1 and 2 exhibited excellent mechanical strength. Moreover, as for the antibacterial article of these Examples 1-2, all were excellent in the antibacterial test and the result of post-processing suitability.

  On the other hand, the antibacterial article of Comparative Example 1 deviating from the range of bamboo: shellac resin = 75: 25 to 25:75 was inferior in post-processing suitability and extremely low in mechanical strength. Similarly, the antibacterial article of Comparative Example 3 was inferior in antibacterial test results and was inappropriate for use as an antibacterial article.

  From the above, the antibacterial article made of the composite material of the present invention in which bamboo and shellac resin are contained in a mass ratio of bamboo: shellac resin = 80: 20 to 30:70 has antibacterial properties, post-processing suitability and mechanical strength. And antibacterial articles having good antibacterial properties and sufficiently practical post-processing suitability and mechanical strength.

1 Graph showing the relationship between the mixing ratio of bamboo and shellac resins and antibacterial properties 2 Graph showing the relationship between the mixing ratio of bamboo and shellac resins and suitability for post-processing and mechanical strength

Claims (8)

Including bamboo and shellac resin,
The compounding ratio of the said bamboo and the said shellac resin is a composite material which is bamboo: shellac resin = 80: 20-30: 70.   The composite material according to claim 1, wherein the bamboo is powdery or fibrous and is dispersed in the shellac resin.   An antibacterial article, wherein the composite material according to claim 1 or 2 is thermoformed.   The antibacterial article according to claim 3, wherein the composite material is in a powder form or a chip form.   The manufacturing method of a composite material including the mixing process which mixes bamboo and shellac resin at 70-120 degrees so that it may become bamboo: shellac resin = 80: 20-30: 70.   The manufacturing method of the composite material of Claim 5 including the primary grinding | pulverization process which grind | pulverizes the said bamboo into a powder form or a fiber form before the said mixing process. A secondary pulverization step of pulverizing the composite material obtained by the method for producing a composite material according to claim 5 or 6 into powder or chips;
A method for producing an antibacterial article, comprising a thermoforming step of thermoforming the obtained pulverized product.   The method for producing an antibacterial article according to claim 7, further comprising a thermosetting treatment step of performing a thermosetting treatment of the shellac resin simultaneously with the thermoforming step or after the thermoforming step.

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