Plastic molded product comprising copper-based compound microparticles and preparation method therefor

Abstract

Provided is a method for manufacturing a molded plastic products having copper-based compound particulates. The method includes the steps of: reacting copper sulfate with sulfuric salt, at a molar ratio of 1:1 in an aqueous solution at a temperature of 1080 C., thereby synthesizing copper sulfide particulates; forming a sheet comprising the copper sulfide particulates dispersed in a thermoplastic resin.

Claims

1. A method for manufacturing a molded plastic products, the method comprising the steps of: reacting copper sulfate with sulfuric salt, at a molar ratio of 1:1 in an aqueous solution at a temperature of 1080 C, thereby synthesizing copper sulfide particulates; and dispersing the copper sulfide particulates in a thermoplastic resin to form a molded plastic product, wherein the copper sulfide particulates have a chemical structure of Cu.sub.xS.sub.y satisfying x/y=0.8 to 1.5, x and y representing values greater than 0; the molded plastic product has an antibioisis that increases gradually as the x/y decreases; and the copper sulfide particulates have an X-ray diffraction pattern that includes peaks corresponding to a crystal structure of copper.

2. The method of claim 1, wherein the molded plastic product has a sulfur concentration of 10-60 mole %.

3. The method of claim 1, wherein the copper sulfide particulates are contained in the thermoplastic resin in an amount of less than 50 wt % based on a total weight of the molded plastic product.

4. The method of claim 1, wherein the dispersing further comprises; dispersing 0.1-5wt % of metal particulates based on a total weight of the molded plastic product, wherein the metal particles have an average particle size smaller than that of the copper sulfide particulates, and the metal particles are formed of at least one metal selected from the group consisting of chromium, manganese, iron, cobalt, nickel and zinc.

5. The method of claim 4, wherein the dispersing further includes: extruding the copper sulfide particulates and the thermoplastic resin in a form of sheet, wherein the sheet is subjected to primary cooling, heat treatment and secondary cooling formed by extrusion, and the formed sheet is subjected to primary cooling.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a picture that shows copper sulfate fine particles manufactured by the examples of the present invention.

(2) FIG. 2 is an XRD graph that shows the crystal structure of copper sulfate manufactured by the examples of the present invention.

(3) FIG. 3 is a photomicrograph in which copper sulfate manufactured by the examples of the present invention is magnified by a factor of 30,000.

DESCRIPTION OF EMBODIMENTS

(4) As the present invention may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the embodiments described in the present invention are not limited by any of the details of the foregoing description, therefore, various variations are possible by a person of ordinary skill in the pertinent art within the range of technical features of the present invention.

(5) Examples of the present invention provide molded plastic products that are relatively cheaper and easier to produce and have fine particles of copper-based compound with economy feasibility and productivity and method of manufacturing the products by manufacturing molded plastic products with copper-based fine particles having copper sulfate dispersed onto the thermoplastic resin. For this, method of producing molded plastic produced by dispersing fine particles of copper-based compound having copper sulfate onto the thermoplastic resin will be disclosed in detail. In addition, antibiosis and conductivity of the molded plastic products will also be disclosed in detail.

(6) In this invention, molded plastic products means products manufactured by extruding or injecting polymeric resin having fine particles of copper-based compound having copper sulfate. Molded plastic products such as fabric or wares can be manufactured through said process. Molded plastic products will be divided into molded fabric products and molded ware products in the following explanation. On the other hand, surface coating methods such as deposition or dyeing are not used to manufacture molded plastic products with improved antibiosis and conductivity in this invention considering economic feasibility and productivity. That is, the present invention chooses dispersing copper-based fine particles having antibiosis and conductivity inside and compounding with resin.

(7) <Production of Molded Fabric Products>

(8) Resins that can be used to produce molded fabric products in the present invention include polypropylene, polyethylene trephthalate, polylactic acid, polyamaide, etc., but not limited to those resins. That is, any resin chosen from the thermoplastic resin group that can be used as a materials for molded fabric products can be applied. Especially, polylactic acid (PLA) is a highly polymerized resin that is produced by fermenting starch from potatoes, corn, etc. polylactic acid (PLA) not only has excellent mechanical property, but also has good biodegradation. Accordingly, the use of polylactic acid (PLA) for fabric, films, molding and medical equipment is gradually increasing. The drawback of polylactic acid (PLA) is that it has lower mechanical property and heat resistivity that polyester resins such as polyethylene trephthalate, a petroleum-based resin. However, the above drawback is gradually improving through the synthesis of copolymer.

(9) Copper-based fine particles in the present invention can include copper sulfide(CuS), copper fluoridation(CuF.sub.2), copper chloride(CuCl.sub.2), etc. however, copper sulfide(CuS) is preferable among them. Copper sulfide are synthesized in forms of fine particles by reacting salt chosen from copper sulfate, sulfide salt, fluoride salt, chloride salt with aqueous solution in the mole ratio of 1:1. The chemical structure of the synthesized copper sulfide is Cu.sub.xM.sub.y, and the synthesis condition is limited in order to satisfy 0.51.5 of the x/y ratio. Here, M means S, F and Cl, but is not limited to them. In addition, M is all kinds of organic components that can produce copper sulfide fine particles by methods mentioned in the present invention. More concretely, M can be one that is chosen from groups 15 to 17 in the periodic table.

(10) Kinds of sulfide salt that can be used in the present invention can include sodium sulfide, iron sulfide, potassium sulfide, zinc sulfide, etc., while the fluoride salt can be one chosen from sodium fluoride, iron fluoride, potassium fluoride, zinc fluoride, etc. Also the chloride salt can be one chosen from sodium chloride, iron chloride, potassium chloride, zinc chloride, etc. Among them, copper sulfide that is synthesized using sodium sulfide and copper sulfate has best antibiosis and deodorization.

(11) On the other hand, if the reaction temperature is below 10 C., the average grain size becomes smaller because reactivity of copper sulfate and salt decreases when synthesizing copper-based particles. Accordingly, antibiosis is good while deodorization becomes worse. If the reaction temperature is over 80 C., density of crystals on the surface of copper sulfide and concentration of copper increase because reaction speed is extremely fast. Accordingly, deodorization is good while antibiosis becomes worse. In addition, if the x/y coupling ratio of the copper-based fine particles is below 0.5, concentration of S, F, Cl, etc. increases excessively. In this case, antibiosis becomes better while deodorization becomes worse. Also in case of over 1.5, concentration of copper increases resulting in better deodorization and worse antibiosis.

(12) In examples of the present invention, it is proper to use compounding process in order to maintain antibiosis and deodorization of fabric for a long time by increasing dispersibility of copper-based fine particles in the thermoplastic resin. Compounding process means mixing more than two kinds of solid matters in a certain component ratio at a certain temperature for a certain amount of time, and then producing master chips by extruding, cooling and cutting. In the compounding process of the present invention, greater than 0 wt % but smaller than 50 wt % of limited thermoplastic resin and copper-based fine particle are mixed at barrel temperature which is 3050 C. higher than the melting temperature of the resin. If concentration of the copper-based fine particles is 0 wt %, improvement of antibiosis cannot be confirmed. Also if concentration of the copper-based fine particles is higher than 50 wt %, antibiosis and deodorization, but the dispersion state of master chips becomes worse. As a result, the thread breaks during thread process.

(13) For compounding process, a compounder with a built-in biaxial and same direction screw is more preferable than a compounder with a single axis screw because it is better dispersibility. Also it is preferable that the L/D range of the compounding equipment is between 30 and 40. The composition of the compounded master chips includes previously known materials for improving property and process as well as the copper-based fine particles in the thermoplastic resin. The previously known materials can be organic adding agents such as compatibilizing agent, dispersing agent, antistatic agent, dying agent, etc., inorganic adding agents for improving activity and functionality, and other metal fine particles. The composition of master chips produced by the compounding process can be diversified according to purpose of use and usage. That is, fiber produced by previously known equipment was produced to fabric for patients' bedding, hospital gowns, hospital workers' duty uniforms, indoor wallpaper of hospitals, etc.

(14) The present invention is described in more detail by examples and comparative examples, but the examples are only illustrative and, therefore, not intended to limit the scope of the present invention. Performance evaluation for fiber produced by the examples and the comparative examples in the present invention was implemented as follows.

(15) (1) Average Diameter

(16) The average diameter of copper-based fine particles are measured with a grain size analyzer (ELS-Z2, Otsuka Electronics Co., Japan)

(17) (2) Ingredient Analysis (x/y composition)

(18) Ingredients of copper-based fine particles (S.sub.xM.sub.y) are analyzed by measuring concentration of Cu and M (one of S, F and Cl) with an inductive coupling plasma mass analyzer (Agilent 7500, Aglient Technologies Inc., U.S.).

(19) (3) Antibiosis

(20) Test lysate was contacted to a specimen using Escherichia Coli (ATCC 25922) as cultures. Then, the test lysate was cultivated by placing at a constant position at 25 C. for 24 hours. And then, antibiosis of the specimen was evaluated by counting the number of bacteria.

(21) (4) Deodorization

(22) 1 g of copper-based fine particles and 10,000 ng/mL of vapor phase formaldehyde were put in a reactor. Then, deodorization of the copper-based fine particles was evaluated by calculating concentration of removed formaldehyde after 5 minutes. At this time, concentration of remained vapor phase formaldehyde was measured with a gas chromatography (Agilent 6890, Aglient Technologies Inc., U.S.)

EXAMPLE 1

(23) Aqueous solution was manufactured by mixing 1 mole of CuSO.sub.4 and Na.sub.2S respectively with deionized water for 30 minutes. Then, copper sulfide (CuS) as shown in FIG. 1 was synthesized by reacting the aqueous solution at 50 C. in an isothermal reactor. At this stage, the x/y ratio of the synthesized ingredient was 1.02. The crystal structure of the synthesized copper sulfide has a unique structure for copper sulfide as shown in FIG. 2. FIG. 3 illustrates shapes of the grains observed with a microscope of 30,000 magnification. According to FIG. 3, there are no peaks because sulfur has no crystal structure, but copper presented peaks at 55, 65, 99, 125 and 137 degrees.

(24) X-ray powder diffraction (XRD, XD-3A, Shimadzu, Japan) was used to observe the fine particles. And then, 40 wt % of copper sulfide was input in PLA resin with a density of 1.2 (g/cm.sup.3), and master chips were made using a compounder with 30 of L/D and a built-in biaxial and same direction screw. Continually, molded fabric products were manufactured by threading the master chips. Nextly, antibiosis and deorderization of the fabric products were measured as proposed above.

EXAMPLE 2

(25) Copper sulfide (CuS) fine particles with the x/y ratio of 1.15 were synthesized by the same method in Example 1. Then, 10 wt % of the copper sulfide was input in PLA resin with a density of 1.2(g/cm.sup.3). Thereafter, fabric molded products were made by the same method in Example 1, and antibiosis and deorderization of the fabric products were measured.

EXAMPLE 3

(26) Copper sulfide (CuS) fine particles with the x/y ratio of 1.08 were synthesized by the same method in Example 1 using CuSO.sub.4 and K.sub.2S instead of CuSO.sub.4 and Na.sub.2S of Example 1. Then, 20 wt % of the copper sulfide were input in PA resin. Thereafter, fabric molded products were made by the same method in Example 1, and antibiosis and deorderization of the fabric products were measured.

EXAMPLE 4

(27) Copper fluoride (CuF.sub.2) fine particles with the x/y ratio of 1.10 were synthesized by the same method in Example 1 using CuSO.sub.4 and NaF instead of CuSO.sub.4 and Na.sub.2S of Example 1. Then, 50 wt % of the copper fluoride was input in PP resin. Thereafter, fabric molded products were made by the same method in Example 1, and antibiosis and deorderization of the fabric products were measured.

EXAMPLE 5

(28) Copper chloride (CuCl.sub.2) fine particles with the x/y ratio of 1.05 were synthesized by the same method in Example 1 using CuSO.sub.4 and NaCl instead of CuSO.sub.4 and Na.sub.2S of Example 1. Then, 5 wt % of the copper chloride was input in PET resin. Thereafter, fabric molded products were made by the same method in Example 1, and antibiosis and deorderization of the fabric products were measured.

COMPARATIVE EXAMPLE 1

(29) A fabric molded product was made of low-density polyethylene (LDPE) and having a diameter of 1 cm and a length of 10 cm was prepared, and the antibacterial activity thereof was measured according to the above-described method.

(30) Table 1 shows comparison among Examples 1 to 5 and Comparative Examples 1 by areas such as the composition ratio of x/y, the diameter of particles (nm), antibiosis (no./mL) and the deordorization (%) of the copper based fine particles, and antibiosis (no./mL) of the molded fabric products according to weight % of the copper based fine particles in the thermoplastic resin. Here, N/A means inaccessible measurement because the number of bacilli of Escherichia Coli (ATCC 25922) is over 10.sup.10.

(31) TABLE-US-00001 TABLE 1 Molded fabric products Copper based Reactants Reaction Copper based fine particle fine particle Copper Temp. Antibiosis Deordorization Content Antibiosis sulfate Salt ( C.) x/y (No./mL) (%) Resin Resin (wt %) (No./mL) Examples 1 CuSO.sub.4 Na.sub.2S 50 1.02 2.5 10.sup.2 75 PLA CuS 40 1.3 10.sup.5 2 CuSO.sub.4 Na.sub.2S 80 1.15 2.9 10.sup.2 85 PLA CuS 10 3.2 10.sup.6 3 CuSO.sub.4 K.sub.2S 65 1.08 3.5 10.sup.2 62 PA CuS 20 9.2 10.sup.5 4 CuSO.sub.4 NaF 70 1.10 2.1 10.sup.2 60 PP CuF.sub.2 50 1.3 10.sup.4 5 CuSO.sub.4 NaCl 60 1.05 2.0 10.sup.2 67 PET CuCl.sub.2 5 6.5 10.sup.6 Comp. 1 / / / / / 5 LDPE / / N/A Examples

(32) According to Table 1, copper based fine particles of Examples 1 to 5 of the present invention were Cu.sub.xM.sub.y, wherein M is chosen from groups 15 to 17 in the periodic table. Also the copper based fine particles have x/y ratios between 0.5 and 1.5 Then, antibiosis of the copper based fine particles falls within the range of 2.010.sup.23.510.sup.2 (no./mL) while deordorizations 6085%. In addition, antibiosis of the molded fabric products consisting of 550 wt % of fine particles of the said examples was 1.310.sup.46.510.sup.6. However, the antibacterial activity of the product of Comparative Example 1, was very low such that it could not be measured. And the deorderization is very low.

(33) Manufacturing Molded Container

(34) A Molded Product for a container according to the present invention is made of thermoplastic resin such as polyethyleneterephthalate, polylatic acid, polyethylene, polypropylene, polycarbonate, polymethylmethacrylate, polyvinylchloride, polyamide and so on. Since polyvinylchloride (PVC) has excellent workability, up to now, it is widely used as a material for a disposable container in medicine. As environmental regulations in the use of polyvinylchloride become seriously determined due to the generation of hazardous substances upon the combustion of polyvinylchloride, a quantity of polyvinylchloride consumption becomes reduced. Contrarily, olefin resin such as low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), etc. is increased in the quantity consumed. At this time, the container includes a receptacle as a fiber molded product for containing objects, and in addition thereto, the container may include consumable goods like tubes and other parts.

(35) The resins used in the present invention are different according to the sizes of the container. According to the viscosity characteristics of the resins, that is, a relatively small-sized container is made of olefin resins like PP and PE, and a middle-sized container is desirably made of polyethyleneterephthalate (PET). A relatively large-sized container is desirably made of polycarbonate (PC). Polymethylmethacrylate (PMMA) and polyvinylchloride (PVC) are generally used for consumable goods in hospital like tubes or other parts. Recently, polylatic acid (PLA) as a bio material derived from corn or potatoes has been used for an injection molded product.

(36) The molded product for a container according to the present invention is made by mixing the thermoplastic resin with 0 to 50 wt % of fine particles of copper-based sulfide and 0.1 to 5 wt % of fine particles of at least one metal selected from the group consisting of chrome, manganese, iron, cobalt, nickel, and zinc, at the same time. At this time, the mixed fine particles of copper-based sulfide desirably contain 10 to 60 mol % of sulfide. If the fine particles contain less than 10 mol % of sulfide, antimicrobial efficiencies become bad, and contrarily, if more than 60 mol % of sulfide, conductivity becomes bad.

(37) On the other hand, if only the fine particles of sulfide like copper sulfide is distributed to the thermoplastic resin and made to the form of fiber, they can be sufficiently used as a fiber molded product having improved antimicrobial efficiencies and conductivity. By the way, if the fine particles of sulfide are made to the form of a sheet for the use of the molded product for a container, their distribution becomes deteriorated to cause a pressure (extrusion pressure) to be raised. In case of a fine-sized sheet, good antimicrobial efficiencies and conductivity can be obtained through the fine particles of sulfide, but in case of a relatively large-sized sheet, the increment of the extrusion pressure should be considered.

(38) So as to prevent the extrusion pressure from being raised, accordingly, 0.1 to 5 wt % of fine particles of at least one metal selected from the group consisting of chrome, manganese, iron, cobalt, nickel, and zinc, which are transition metals selected in the period 4 of a periodic table are added. If the transition metals are mixed with the copper-based compound, they have more excellent distribution, antimicrobial efficiencies and conductivity when compared with main group metals like Al.

(39) So as to reduce the extrusion pressure, on the other hand, the average sizes of the fine particles of metal are desirably smaller than those of the fine particles of copper-based sulfide. In the process where the fine particles of metal are mixed with the thermoplastic resin, further, if the mixed concentration of the fine particles of metal is less than 0.1 wt % or more than 5 wt %, the extrusion pressure is increased. As mentioned above, the fine particles of metal are added just to control the extrusion pressure, and the appropriate antimicrobial efficiencies and conductivity are obtained through the copper-based sulfide. Therefore, the molded product for a container according to the present invention can be made, without the addition of the fine particles of metal. Of course, the added fine particles of metal are appropriately selected so that they do not give any bad influence on the antimicrobial efficiencies and conductivity required for the molded product for a container according to the present invention. At this time, the extrusion pressure for molding is desirable in the range of 0.05 to 1 P/h.

(40) According to the present invention, mixing was adopted to enhance the distribution between the resin and the fine particles and thus conducted at a barrel temperature higher by 30 to 50 C. than the melting temperature of the resin. The mixing was carried out by means of a mixer wherein co-rotating twin screws having more excellent distribution than a single screw are embedded. The ratio of L/D of the mixer was in the range of 30 to 40. The mixed resin was kept to a form of chips in a bunker, and after that, the chips were extruded at the condition of the extrusion temperature higher by 30 to 50 C. than the melting temperature of the used plastic resin. Next, molding, first cooling, heat treatment, and second cooling were carried out sequentially to make a plastic container having a desired shape.