JP7594458B2 - Antibacterial resin molded product and its manufacturing method - Google Patents

Description

The present invention relates to an antibacterial resin molded product and a method for producing the same.

Antibacterial resin molded products containing antibacterial agents are known, for example from Patent Document 1.

Japanese Patent Application Publication No. 9-216563

Incidentally, the above-mentioned patent document describes a method for producing an antibacterial resin molded product by forming an antibacterial layer on the cavity surface of a mold in advance and then pouring a resin into the mold. In this case, there is a possibility that the antibacterial layer formed on the cavity surface of the mold will be washed away when the resin is poured in.
Other antibacterial resin molded products are often made by injection molding using resins containing antibacterial agents. However, in this method, only the antibacterial agent exposed on the surface contributes to the antibacterial properties, while the antibacterial agent buried in the resin does not contribute to the antibacterial properties, resulting in a large amount of antibacterial agent that does not participate in the antibacterial action. This results in poor utilization efficiency of the antibacterial agent.
In addition, organic antibacterial agents cannot be used because they are altered by the heat during injection molding.

The present invention aims to provide an antibacterial resin molded product that can use either inorganic or organic antibacterial agents and has improved utilization efficiency of the antibacterial agent, and a method for producing the same.

According to one aspect of the present invention,
A method for producing an antibacterial resin molded product having a thermoplastic resin body and an antibacterial layer provided on at least a portion of a surface of the body, comprising:
An upper mold and a first lower mold that open and close vertically are closed to form a first cavity for forming the main body portion, and a thermoplastic resin is poured into the first cavity;
The thermoplastic resin is cooled and solidified within the closed upper mold and the first lower mold to mold the main body portion;
While the main body portion is held by the upper die, the upper die and the first lower die are opened;
replacing the first lower die with a second lower die whose temperature is lower than the temperature of the main body portion held by the upper die;
The upper mold and the second lower mold are closed to form a second cavity for forming the antibacterial layer between the main body portion and the second lower mold;
A liquid urethane resin raw material containing an inorganic or organic antibacterial agent is poured into the second cavity;
The second lower mold is heated to harden the urethane resin raw material, thereby forming the antibacterial layer.

In the above-mentioned production method of the present invention,
The specific gravity of the antibacterial agent may be greater than the specific gravity of the urethane resin raw material.

In the above-mentioned production method of the present invention,
The urethane resin raw material may be a two-liquid type in which two kinds of liquids are mixed and then poured into the second cavity.

In the above-mentioned production method of the present invention,
The viscosity of the urethane resin raw material poured into the second cavity may be 20 mPa·s or more and less than 150 mPa·s.

In the above-mentioned production method of the present invention,
A curing time for hardening the antimicrobial layer may be longer than a cooling time for the body portion in the first cavity.

In the above-mentioned production method of the present invention,
The urethane resin raw material containing the antibacterial agent may be stirred in a tank for storing the urethane resin raw material before being poured into the second cavity.

In the above-mentioned production method of the present invention,
The thermoplastic resin may be an ABS (acrylonitrile butadiene styrene) resin or a PC-ABS (polycarbonate ABS) resin.

According to one aspect of the present invention,
A body portion made of a thermoplastic resin;
An antibacterial resin molded product having an antibacterial layer provided on at least a part of a surface of the main body,
The antibacterial layer is made of a urethane resin containing an inorganic or organic antibacterial agent,
the average particle size of the antibacterial agent is 1/1000 or more and less than 1/5 of the thickness of the antibacterial layer;
An antibacterial resin molded article is provided in which the concentration of the antibacterial agent in the surface layer of the antibacterial layer is higher than the concentration of the antibacterial agent in the center portion in the thickness direction of the antibacterial layer.

In the antibacterial resin molded article of the present invention,
The antibacterial layer may have a thickness of 50 μm or more.

In the antibacterial resin molded article of the present invention,
The antibacterial agent may have an average particle size of 5 μm or more.

In the antibacterial resin molded article of the present invention,
The thermoplastic resin may be an ABS (acrylonitrile butadiene styrene) resin or a PC-ABS (polycarbonate ABS) resin.

The present invention provides an antibacterial resin molded article and a method for producing the same, which can use either inorganic or organic antibacterial agents and has improved utilization efficiency of the antibacterial agent.

1 is a cross-sectional view of an antibacterial resin molded article according to the present invention. 1 is a schematic diagram showing a state in which an upper mold and a first lower mold are closed to form a first cavity. FIG. 4 is a schematic diagram showing a state in which a thermoplastic resin is poured into a first cavity to form a main body portion. FIG. 11 is a schematic diagram showing a state in which an upper mold and a first lower mold are opened while a main body portion is held by the upper mold. FIG. FIG. 13 is a schematic diagram showing a state in which a first lower die and a second lower die are replaced. 4 is a schematic diagram showing how a urethane resin raw material is poured into a second cavity formed by an upper mold and a second lower mold. FIG. FIG. 2 is a schematic diagram showing how an antibacterial layer is formed by curing a urethane resin raw material. 13 is a diagram showing the state in which a liquid urethane resin raw material containing an antibacterial agent is poured into a second cavity. FIG.

The present invention will be described below with reference to the drawings based on the embodiments. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and duplicated descriptions will be omitted as appropriate. Furthermore, the embodiments are illustrative rather than limiting the invention, and all of the features and combinations thereof described in the embodiments are not necessarily essential to the invention.

Figure 1 is a cross-sectional view of an antibacterial resin molded product 1 according to an embodiment of the present invention. As shown in Figure 1, the antibacterial resin molded product 1 has a body 2 made of thermoplastic resin and an antibacterial layer 3 provided on at least a portion of the surface of the body 2. The body 2 is made of a thermoplastic resin such as ABS (acrylonitrile butadiene styrene) resin or PC-ABS (polycarbonate ABS) resin. It is preferable that the thickness T of the antibacterial layer 3 is 50 μm or more.

The antibacterial layer 3 is composed of a urethane resin containing an inorganic or organic antibacterial agent 4 (see Figure 8). A particulate antibacterial agent 4 can be used as the antibacterial agent 4. The average particle size of the antibacterial agent 4 is preferably 5 μm or more. The average particle size can be determined as the volume average particle size (D50) using a laser scattering diffraction method particle size distribution measuring device.

For example, inorganic antibacterial agents such as a silver-supported inorganic antibacterial agent and a copper-supported inorganic antibacterial agent can be used as the particulate antibacterial agent 4. For example, the following can be used as the inorganic antibacterial agent.
Silver-supported inorganic antibacterial agents and copper-supported inorganic antibacterial agents using phosphates such as zirconia phosphate, aluminum phosphate, hydroxyapatite, and calcium phosphate as carriers;
Silver-supported inorganic antibacterial agents and copper-supported inorganic antibacterial agents using silicates such as zeolite and silica gel as carriers;
Silver-supported inorganic antibacterial agents and copper-supported inorganic antibacterial agents that use glass, activated carbon, carbon fiber, etc. as carriers

Alternatively, the following can be employed as organic antimicrobial agents:
Aldehyde-based antibacterial agents such as α-bromocinnamaldehyde; Carboxylic acid-based antibacterial agents such as sodium benzoate; Phenol-based antibacterial agents such as 2-benzyl-4-chlorophenol; Organic iodine-based antibacterial agents such as 3-iodo-2-propyl butyl carbamate; Penzimidazole-based antibacterial agents such as 2-(4-thiazolyl)pentimidazole; Isothiazolin-based antibacterial agents such as 2-n-octyl-4-isothiazolin-3-one; Nitrile-based antibacterial agents such as 2,4,5,6-tetrachloroisophthalonitrile; Pyridine-based antibacterial agents such as 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine; Triazine-based antibacterial agents such as N,N',N"-trishydroxyethylhexahydro-s-triazine; N-haloalkylthio-based antibacterial agents such as N-(fluorodichloromethylthio)phthalimide; Quaternary ammonium salt-based antibacterial agents such as didecyldimethylammonium chloride. Pyrithione-based antibacterial agents such as bis(pyridine-2-thiol-l-oxide) zinc salt; Organocopper-based antibacterial agents such as 8-oxyquinoline copper; Organoarsenic-based antibacterial agents such as 10,10'-oxybisphenoxaarsine; Organic antibacterial agents derived from plants such as wasabi, mustard, and cypress.

Next, a method for producing the antibacterial resin molded product 1 will be described with reference to FIGS.
2, the upper mold 10 and the first lower mold 20 are closed to form a first cavity C1 for forming the main body 2. The upper mold 10 and the first lower mold 20 are movable in the vertical direction relative to each other. Here, it is assumed that the upper mold 10 does not move in the vertical direction, and the first lower mold 20 is movable in the vertical direction.

Next, as shown in FIG. 3, molten thermoplastic resin R1 is poured into the first cavity C1 formed by the upper die 10 and the first lower die 20. After the first cavity C1 is filled with the thermoplastic resin R1, the upper die 10 and/or the first lower die 20 are cooled to cool and solidify the thermoplastic resin R1, thereby forming the main body 2.

Next, as shown in FIG. 4, the upper mold 10 and the first lower mold 20 are opened while the upper mold 10 holds the main body 2. Here, the main body 2 is cooled and shrinks more than the upper mold 10, so that the main body 2 is attached to the upper mold 10.

The method of holding the main body 2 on the upper mold 10 is not limited to this example. The main body 2 may be provided with a protrusion that protrudes toward the upper mold 10 to prevent it from escaping in the direction of the first lower mold 20. Alternatively, the upper mold 10 may be provided with a protrusion that protrudes toward the first cavity C1 to prevent the main body 2 from escaping in the direction of the first lower mold 20. Alternatively, such a protrusion provided on the upper mold 10 may be constituted by a movable pin that can advance into the first cavity C1.

Fig. 5 is a schematic diagram showing the state of replacing the first lower mold 20 with the second lower mold 30. As shown in Fig. 5, the first lower mold 20 is replaced with the second lower mold 30 set to a temperature lower than the temperature of the main body 2 held by the upper mold 10. Here, the upper mold 10 is moved in the left-right direction to above the second lower mold 30, which has been cooled. The second lower mold 30 is cooled to a temperature lower than the temperature of the main body 2 by water cooling or air cooling.
Note that setting the second lower mold 30 to a temperature lower than the temperature of the main body 2 held by the upper mold 10 may mean setting the temperature of the second lower mold 30 so that the cavity surface of the second lower mold 30 is lower than the temperature obtained by measuring the temperature of the main body 2 held by the upper mold 10 when the molds are opened. Alternatively, the temperature of the main body 2 held by the upper mold 10 when the molds are opened may be experimentally confirmed in advance, and the temperature of the second lower mold 30 may be set to be equal to or lower than this temperature. Alternatively, since the temperature of the main body 2 is higher than the temperature of the upper mold 10 when the molds are opened, the temperature of the second lower mold 30 may be set to be equal to or lower than the temperature of the upper mold 10.

Next, as shown in FIG. 6, the upper mold 10 and the second lower mold 30 are closed to form a second cavity C2 for forming the antibacterial layer 3 between the main body portion 2 and the second lower mold 30. The cavity formed by the upper mold 10 and the second lower mold 30 is composed of a space for accommodating the main body portion 2 and the second cavity C2 for forming the antibacterial layer 3. Therefore, the cavity formed by the upper mold 10 and the second lower mold 30 is larger than the first cavity C1 for forming the main body portion 2.

Next, as shown in FIG. 7, liquid urethane resin raw material R2 containing antibacterial agent 4 is poured into second cavity C2. The second lower die 30 is then heated to react and harden the urethane resin raw material R2 to form antibacterial layer 3. In this way, an antibacterial resin molded product 1 is formed in which antibacterial layer 3 is provided on at least a portion of the surface of main body 2.

According to the manufacturing method of this embodiment, the main body 2 and the antibacterial layer 3 are cured in separate processes. The curing temperature of the urethane resin raw material R2 that forms the antibacterial layer 3 is 100 degrees or less, which is lower than the heat resistance temperature at which the antibacterial effect of the organic antibacterial agent 4 is lost. Therefore, the antibacterial effect of the organic antibacterial agent 4 can be maintained when the urethane resin raw material R2 is cured to form the antibacterial layer 3.

8 is a diagram showing a state in which the liquid urethane resin raw material R2 containing the antibacterial agent 4 is poured into the second cavity C2. The flow rate is slower near the cavity surface 31 than at the center of the thickness direction of the second cavity C2 because the resistance to the fluid flowing in the second cavity C2 is greater near the cavity surface 31. When the urethane resin raw material R2 flows through the second cavity C2, the particulate antibacterial agent 4 is less likely to remain in the center of the thickness direction of the second cavity C2 due to the fountain flow phenomenon at the flow front, and is more likely to accumulate near the cavity surface 31. For this reason, in the antibacterial resin molded product 1 obtained by the manufacturing method of this embodiment, the concentration of the antibacterial agent 4 in the surface layer of the antibacterial layer 3 is higher than the concentration of the antibacterial agent 4 in the center of the thickness direction of the antibacterial layer 3. For this reason, the antibacterial agent 4 is more likely to be exposed on the surface of the antibacterial layer 3, and the utilization efficiency of the antibacterial agent 4 is improved.
The average particle size of the antibacterial agent 4 is preferably 1/1000 or more and 1/5 of the thickness of the antibacterial layer 3. If the average particle size of the antibacterial agent 4 is less than 1/1000, the antibacterial agent 4 becomes difficult to disperse in the urethane resin raw material R. If the average particle size of the antibacterial agent 4 is more than 1/5, the antibacterial agent 4 becomes difficult to be carried through the second cavity C2 by the urethane resin raw material R2.

The specific gravity of the antibacterial agent 4 is preferably greater than that of the urethane resin raw material R2. If the specific gravity of the antibacterial agent 4 is greater than that of the urethane resin raw material R2, the antibacterial agent 4 is likely to accumulate on the cavity surface 31 of the second lower mold 30 that constitutes the lower surface of the second cavity C2 in the process of forming the antibacterial layer 3. This makes it easier to position the antibacterial agent 4 on the surface of the antibacterial layer 3. The specific gravity of the antibacterial agent 4 is preferably 1.5 times or more the specific gravity of the urethane resin raw material R2. More preferably, the specific gravity of the antibacterial agent 4 is more than twice the specific gravity of the urethane resin raw material R2.

The urethane resin raw material R2 is preferably a two-liquid type in which two types of liquid are mixed and then poured into the second cavity C2. The two-liquid type urethane resin raw material R2 allows the hardening speed of the urethane resin raw material R2 to be adjusted by, for example, adjusting the blending ratio of the two types of liquid. Therefore, the hardening speed can be adjusted so that the antibacterial agent 4 moves within the urethane resin raw material R2 so that the antibacterial agent 4 is exposed to the surface before the urethane resin raw material R2 hardens.

The viscosity of the urethane resin raw material R2 poured into the second cavity C2 is preferably 20 mPa·s or more and less than 150 mPa·s. If the viscosity of the urethane resin raw material R2 is less than 20 mPa·s, the antibacterial agent 4 will settle quickly in the tank 32 even if the urethane resin raw material R2 containing the antibacterial agent 4 is stirred, and the concentration of the antibacterial agent 4 in the poured urethane resin raw material R2 will vary, and the antibacterial agent 4 will tend to be concentrated in the antibacterial layer 3. If the viscosity of the urethane resin raw material R2 is greater than 150 mPa·s, the urethane resin raw material R2 will not flow easily in the second cavity C2. In addition, the antibacterial agent 4 will not easily mix with the urethane resin raw material R2. Furthermore, the antibacterial agent 4 will not easily settle in the second cavity C2.

The curing time for hardening the antibacterial layer 3 in the process shown in FIG. 7 is preferably longer than the cooling time for the main body portion 2 in the first cavity C1 in the process shown in FIG. 3. This is because the longer the curing time for the antibacterial layer 3, the easier it is to ensure that the antibacterial agent 4 has time to move (settle) in the urethane resin raw material R2.

It is preferable to pour the urethane resin raw material R2 into the second cavity C2 with the particulate antibacterial agent 4 dispersed as evenly as possible in the urethane resin raw material R2. For this reason, it is preferable to stir the urethane resin raw material R2 containing the antibacterial agent 4 in the tank 32 (see FIG. 6) that stores the urethane resin raw material R2 before pouring it into the second cavity C2.

When manufacturing antibacterial resin molded articles 1 continuously, the mold is opened from the state shown in FIG. 7 to remove the antibacterial resin molded article 1, and the upper mold 10 is moved left and right to above the first lower mold 20, after which cooling of the second lower mold 30 is started to prepare for the process shown in FIG. 5.

In the above explanation, an example was described in which the upper mold 10 is movable in the left-right direction and the first lower mold 20 and the second lower mold 30 are movable in the up-down direction, but the present invention is not limited to this. The upper mold 10 may be movable in the left-right direction and the up-down direction, and the first lower mold 20 and the second lower mold 30 may be fixed. Alternatively, the upper mold 10 may be fixed, and the first lower mold 20 and the second lower mold 30 may be movable in the left-right direction and the up-down direction.

The present invention is not limited to the above-described embodiment, and can be modified and improved as appropriate.
Furthermore, the material, shape, size, value, form, number, location, and the like of each component in the above-described embodiment are arbitrary and not limited as long as they can achieve the present invention.

Reference Signs List 1 Antibacterial resin molded product 2 Main body 3 Antibacterial layer 4 Antibacterial agent 10 Upper mold 20 First lower mold 30 Second lower mold 31 Cavity surface 32 (Storage of urethane resin raw material) Tank C1 First cavity C2 Second cavity R1 Thermoplastic resin R2 Urethane resin raw material

Claims (10)

A method for producing an antibacterial resin molded product having a thermoplastic resin body and an antibacterial layer provided on at least a portion of a surface of the body, comprising:
An upper mold and a first lower mold that open and close vertically are closed to form a first cavity for forming the main body portion, and a thermoplastic resin is poured into the first cavity;
The thermoplastic resin is cooled and solidified within the closed upper mold and the first lower mold to mold the main body portion;
While the main body portion is held by the upper die, the upper die and the first lower die are opened;
replacing the first lower die with a second lower die whose temperature is lower than the temperature of the main body portion held by the upper die;
The upper mold and the second lower mold are closed to form a second cavity for forming the antibacterial layer between the main body portion and the second lower mold;
A liquid urethane resin raw material containing an inorganic or organic antibacterial agent is poured into the second cavity;
The second lower mold is heated to harden the urethane resin raw material and form the antibacterial layer. The method for producing an antibacterial resin molded product according to claim 1, wherein the specific gravity of the antibacterial agent is greater than the specific gravity of the urethane resin raw material. The method for manufacturing antibacterial resin molded products according to claim 1, wherein the urethane resin raw material is a two-liquid type in which two types of liquid are mixed and then poured into the second cavity. The method for producing an antibacterial resin molded product according to claim 1, wherein the viscosity of the urethane resin raw material poured into the second cavity is 20 mPa·s or more and less than 150 mPa·s. The method for manufacturing an antibacterial resin molded product according to claim 1, wherein the curing time for curing the antibacterial layer is longer than the cooling time of the main body portion in the first cavity. The method for producing an antibacterial resin molded product according to claim 1, wherein the urethane resin raw material containing the antibacterial agent is stirred in a tank that stores the urethane resin raw material before pouring it into the second cavity. The method for manufacturing antibacterial resin molded products according to claim 1, wherein the thermoplastic resin is ABS (acrylonitrile butadiene styrene) resin or PC-ABS (polycarbonate ABS) resin. A body portion made of a thermoplastic resin;
An antibacterial resin molded product having an antibacterial layer provided on at least a part of a surface of the main body,
The antibacterial layer is made of a urethane resin containing an inorganic or organic antibacterial agent,
the average particle size of the antibacterial agent is 1/1000 or more and less than 1/5 of the thickness of the antibacterial layer;
a concentration of the antibacterial agent in a surface layer of the antibacterial layer is higher than a concentration of the antibacterial agent in a center portion in a thickness direction of the antibacterial layer;
The antibacterial resin molded product , wherein the thermoplastic resin is ABS (acrylonitrile butadiene styrene) resin or PC-ABS (polycarbonate ABS) resin . The antibacterial resin molded product according to claim 8, wherein the antibacterial layer has a thickness of 50 μm or more. The antibacterial resin molded product according to claim 8, wherein the average particle size of the antibacterial agent is 5 μm or more.

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