JPH0229691B2 - KINZOKUDOOGANJUSURUSERUROOSUSEIKEITAIOYOBISONOSEIZOHOHO - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a cellulose molded body containing metallic copper and having conductivity and bactericidal properties, and a method for manufacturing the same. Among metals, copper is an excellent conductive substance and has sterilizing power against microorganisms and living organisms, and recently there has been a lot of interest in its application to conductivity and sterilizing properties. For example, conductive films and fibers are useful in the electrical and electronic industries, and are used in many applications such as electrostatic shielding materials for electrical equipment and electronic equipment, sheet heating element materials, and coating materials inside and outside the insulation layer of power cables. Various conductive films and fibers have been developed for various purposes. Copper's antibacterial properties are also well known, including the fact that copper sulfate can be added to aquarium water to inhibit the growth of green algae, and that copper doorknobs are normally sterile. For example, it is maintained. It is an object of the present invention to impart such excellent effects of copper to polymeric substances, particularly cellulose. Conventionally, cellulose molded bodies containing metallic copper have been obtained by filling and blending fine powder of metallic copper, and metallic copper is present throughout the molded body. However, the molded product obtained in this way has the following drawbacks. (1) When a molded body is obtained by blending metallic copper fine powder with a cellulose solution, as the blending amount increases, the spinnability and film-forming properties of the mixture deteriorate significantly. (2) When blending metallic copper fine powder, increasing the blending amount significantly reduces the mechanical strength of the compact, so the blending amount is limited from the viewpoint of strength. (3) The fine powder easily falls off during the wet spinning treatment of a blended solution of fine metallic copper powder, such as coagulation, regeneration, and drying. (4) Metallic copper fine powder is easily oxidized by the atmosphere of the blended solution. The method of blending fine metallic copper powder has a number of drawbacks as described above, and until now, the use of cellulose molded bodies containing metallic copper for materials that require electrical conductivity and sterilization properties has been almost impossible. has not been done. Additionally, there are some that have metallic copper present on the surface of the material. For example, there are materials in which metallic copper is vacuum-deposited on the surface of the material, materials in which the surface of the material is plated with copper, materials in which a copper oxide compound is attached and then reduced, and materials in which an adhesive containing metallic copper is applied to the surface. be. However, these materials are characterized by the presence of metallic copper only on the surface of the material, and cannot be made to exist over the entire surface of the material. In view of these problems, the present inventors conducted research to create a molded body containing metallic copper throughout the cellulose molded body, and finally arrived at the present invention. The object of the present invention is to contain metal copper, which exhibits sufficient strength during molding, has excellent flexibility and flexibility, and has excellent conductivity and sterilization properties, throughout the cellulose molded body. An object of the present invention is to provide a molded article and a method for manufacturing the same. The gist of the present invention for achieving such an object of the present invention is to form a coordination compound of cellulose and copper from a copper ammonia cellulose solution, and then to reduce the compound to form a coordination compound containing metallic copper. The cellulose molded body and the copper ammonia cellulose solution are extruded through a molding die, introduced into a coagulation solution bath and solidified, and then dried to reduce the moisture content to 50% by weight or less, and the dried molded body is reduced. The present invention provides a method for producing a cellulose molded article containing metallic copper, which comprises immersing it in a chemical solution and reducing it. Examples of the cellulose solvent containing a copper compound include copper-amine complex salt solutions such as copper hydroxide-ammonia and copper hydroxide-ethylenediamine, but copper-ammonia solutions are particularly preferred in the present invention. Furthermore, the molded product referred to in the present invention refers to all forms obtained from the cuprammonium cellulose solution, and typical molded products include filaments, hollow fibers, films, and the like. As is already known, in a cuprammonium cellulose solution, cellulose is dissolved in an aqueous solution of a copper ammonium complex salt, forming a cellulose-copper-ammonium complex salt represented by the following formula (). This cupric ammonia cellulose solution undergoes partial hydrolysis by coagulating with hot water, a coagulant such as an alkali, and most of the ammonia and part of the copper are diffused out and are expressed by the following formula (). A compound in which copper and cellulose are coordinated is formed. At the same time, during this coagulation process, filaments, hollow fibers,
Alternatively, it can be formed into a film or the like. The copper cellulose coordination compound () obtained in this way is a compound containing approximately one copper atom per one unit of glucose, and the copper atoms are regularly arranged within the cellulose molecule and form strong bonds. It is then shaped into a predetermined shape. By subjecting this copper cellulose coordination compound () to a reduction treatment, a cellulose molded article containing metallic copper of the present invention can be obtained. The method for obtaining the above-mentioned molded article of the present invention will be explained in detail below. Copper ammonia cellulose solution (composition: cellulose concentration 10%, ammonia concentration 7%, copper concentration 3.6%), which is usually used industrially.Hereinafter, in the present invention, % means % by weight unless otherwise specified.
) is extruded through a forming die to form a filament, hollow fiber, or film, and introduced into a coagulating liquid bath to impart a coagulating effect. The cuprammonium cellulose solution is sufficiently coagulated in a coagulation liquid bath and formed into the above-mentioned molded body. The solidified molded body is once dried, and its moisture content is reduced to 50% or less.
Preferably it is 20% or less. solidified molded body,
In other words, a large amount of water (approximately 200%) is attached to the coordination compound of copper and cellulose. This adhered water is
It has the effect of suppressing the reducing action in the next reduction treatment, and if it contains 50% or more water, it will not be completely reduced to metallic copper, resulting in a black molded body containing cuprous oxide. Next, by immersing the molded body dried to a predetermined moisture content in a reducing agent solution, the copper contained in the molded body can be reduced to metallic copper. Boron hydride compounds are particularly suitable as reducing agents.
And preferably sodium borohydride is used. The concentration of the reducing agent solution varies depending on the amount of the substance to be reduced, but 0.1 to 0.6% is appropriate. 0.1
If it is less than 0.6%, the reducing ability is weak and metal copper cannot be reduced sufficiently, and if it exceeds 0.6%, the reducing effect is strong but the reduction efficiency is poor and uneconomical. The most preferred range is 0.2-0.4%. A reduction catalyst is used for the reduction treatment. The reduction catalyst varies depending on the type of reducing agent, but when using sodium borohydride as the reducing agent, alkali metal carbonates and alkali metal hydrogen carbonates are suitable;
Preferably potassium hydrogen carbonate is used. The appropriate concentration is 1 to 6%. If it is less than 1%, the decomposition reaction of sodium borohydride is slow and sufficient reduction treatment cannot be performed. If it exceeds 6%, the decomposition reaction will be rapid and uniform reduction treatment will not be possible. The most preferred range is 2-4%. After the reduction treatment, a cellulose molded body containing metallic copper is obtained by sufficiently washing with water and drying. The molded article of the present invention thus obtained has a smooth surface and the luster of metallic copper, has the excellent electrical conductivity and sufficient sterilizing power of metallic copper, and has mechanical properties. The strength is also sufficient,
It also has excellent flexibility and flexibility. The molded article of the present invention was observed using an electron microscope, but no metallic copper particles could be observed even when magnified 8000 times. It is presumed that such a characteristic state of the metallic copper arranged in the molded article of the present invention is closely related to the degree of dispersion of the metallic copper into the cellulose microstructure. The cellulose molded article containing metallic copper of the present invention is thought to be produced through a compound in which approximately one copper atom is coordinated to the glucose unit of cellulose, and therefore, it is considered that the cellulose molded article containing metallic copper is produced by filling and blending ordinary metallic copper fine powder into cellulose. It is thought that the degree of dispersion is significantly different from the case. Generally, cellulose is thought to form a molecular chain with glucose as its minimum unit, and the molecular chain extends through crystalline and amorphous regions, forming so-called gross micelles. In the present invention, the copper atom coordinated to glucose, which is the smallest unit of cellulose, is reduced,
It is thought that metallic copper exists regularly in very fine regions of cellulose, is arranged throughout the entire region, and exists in a state that makes it difficult to break the molecular chains of cellulose. On the other hand, when fine powder of metallic copper is blended, the particle size of the fine powder is as large as 0.1 to 10 microns, and although it exists in a dispersed state throughout the molded body, it is far from being uniformly dispersed, and of course there is no regularity. Furthermore, particles having the above-mentioned particle size may be dispersed in a state where the molecular chains of cellulose are cut, which may cause a decrease in the mechanical strength of the molded article. As mentioned above, the cellulose molded article containing metallic copper of the present invention has an innovative feature in its structure. Therefore, the molded product has the luster of metallic copper and has a smooth surface. It also has sufficient mechanical strength for molding and has excellent flexibility and flexibility. Furthermore, because it contains metallic copper arranged in the above-mentioned characteristic structure, it has good conductivity.
Needless to say, it has excellent bactericidal properties. Next, the present invention will be explained in detail with reference to Examples. Example 1 A cuprammonium cellulose solution prepared by a known method and having a composition of 10% cellulose, 7% ammonia, and 3.6% copper was passed through a slit die into a coagulation bath of 11% caustic soda solution at 30°C. It was extruded and formed into a film. The sufficiently coagulated film was washed with water and then dried in a hot air dryer at 100°C so that the moisture content of the film was 15%. This film was immersed for 3 minutes in an aqueous solution at 30°C consisting of a sodium borohydride concentration of 0.3% and a potassium hydrogen carbonate concentration of 3% to perform a reduction treatment. After the reduction treatment, it was washed with water, immersed in a 10% glycerin solution, and air-dried to obtain a cellulose film containing metallic copper. The cellulose film thus obtained had the luster of metallic copper, was strong and flexible. The properties of this film are shown in Table 1 as Example 1. As Comparative Example 1, a film extruded by the same method as above and coagulated with caustic soda was
The characteristics of the transparent film obtained by regenerating with 5% sulfuric acid at After blending and coagulating this blend stock solution by extruding it in the same manner as above, it was heated at 30°C.
Table 1 shows the properties of films containing fine metallic copper powder obtained by regeneration with 5% sulfuric acid.

[Table] As can be seen from Table 1, the cellulose film containing metallic copper of the present invention exhibits excellent electrical conductivity and has the performance of having little decrease in mechanical strength. Example 2 A cuprammonium cellulose spinning dope having the same composition as in Example 1 was used and extruded in a circular manner through an annular nozzle, while isopropyl myristate was injected into the center of the cuprammonium cellulose solution from the center of the annular nozzle. Filled and extruded. The hole diameter of the annular nozzle was 5 mm, the extrusion rate of the spinning dope was 18 ml/min, and the extrusion rate of isopropyl myristate was 4 ml/min. The extruded spinning stock solution is allowed to fall freely 300 mm into the air, and then heated at 30℃ and 11%.
The filament was introduced into an aqueous solution of caustic soda and coagulated to form a filament, which was then wound into a skein at a speed of 95 m/min. Next, the wound vines were thoroughly washed with water and air-dried to a moisture content of 20%, and then the sodium borohydride concentration was 0.5% and the potassium carbonate concentration was 3%.
% and boric acid at 30° C. for 5 minutes. After that, the skeins were washed with water, air-dried, and then cut and left indoors for several hours to remove the isopropyl myristate filled in the hollow fibers and obtain cellulose hollow fibers containing metallic copper. Ta. The hollow fiber thus obtained had the luster of metallic copper. The properties of this hollow fiber are shown in Table 2 as Example 2. In addition, as Comparative Example 3, transparent hollow fibers obtained by spinning hollow fibers in the same manner as above and solidifying them with caustic soda were regenerated with 7% sulfuric acid at 30°C (after drying, cut them to obtain hollow fibers). In addition, as Comparative Example 4, a fine powder of metallic copper (particle size 1 to 5 μm) was blended into a spinning dope having the same composition as in Example 1. This blend stock solution was spun and solidified in the same manner as above, and then heated at 30°C.
Table 2 shows the properties of the hollow fibers obtained by regenerating them with 5% sulfuric acid, washing with water, drying, cutting, and removing the hollow agent.

[Table] As can be seen from Table 2, the cellulose hollow fibers containing metallic copper of the present invention exhibit excellent electrical conductivity and are characterized by little decrease in mechanical strength. Example 3 A cuprammonium cellulose spinning stock solution having the same composition as in Example 1 was extruded from a one-hole spinneret with a diameter of 0.6 mm into a spinning funnel filled with spinning water.
Sufficient coagulation was carried out under flowing tension in a container to form a monofilament. The temperature and flow rate of the spinning water were 53° C. and 200 ml/min, and the coagulated monofilament was wound into a skein. Next, the strand-shaped monofilament was thoroughly washed with water, and then dried in a hot air dryer at 90°C to a moisture content of 20%. Thereafter, it was immersed for 5 minutes in an aqueous solution at 30° C. containing 0.3% sodium borohydride and 3% potassium bicarbonate for reduction treatment. After the reduction treatment, it was washed with water and air-dried to obtain a cellulose monofilament containing metallic copper. The monofilament thus obtained had the luster of metallic copper, and its properties are shown in Table 3 as Example 3. In addition, as Comparative Example 5, the characteristics of cellulose monofilament obtained by regenerating after coagulation were investigated, and as Comparative Example 6, fine metallic copper powder (with particle size) was added to the spinning dope having the same composition as in Example 1. Blend 1~5 μ)
This blend stock solution was spun and coagulated in the same manner as above, then regenerated with 5% sulfuric acid at 30°C, washed with water, and dried. The properties of the monofilaments obtained are shown in Table 3.

[Table] As can be seen from Table 3, the cellulose monofilament containing metallic copper of the present invention has excellent electrical conductivity and is characterized by little decrease in mechanical strength.

Claims (1)

[Claims] 1. A cellulose molded article containing metallic copper obtained by reducing a coordination compound of cellulose and copper formed from a cupric ammonia cellulose solution. 2. Extrude the cuprammonium cellulose solution through a molding die, introduce it into a coagulation liquid bath and coagulate it, and then dry it once to reduce its moisture content to 50% by weight or less,
A method for producing a cellulose molded body containing metallic copper, which comprises reducing the dried molded body by immersing it in a reducing agent solution. 3. A method for producing a cellulose molded article containing metallic copper according to claim 2, which uses sodium borohydride as a reducing agent.