CN1287017C - Chitin amine/polyviny vinyl alcohol composite fiber and its manufacturing method - Google Patents

Abstract

The invention discloses a chitosan-polyvinyl alcohol composite fiber with a skin-core structure and a manufacturing method thereof. The polyvinyl alcohol spinning stock solution is used as the core layer, and the chitosan or chitosan and polyvinyl alcohol blend spinning stock solution is used. It is the cortex, which is extruded from the sheath-core composite spinneret, formed by spinning, and then drawn and washed to obtain the composite fiber; the composite fiber is further treated with formaldehyde or glutaraldehyde acetalization to obtain the composite fiber. Chitosan and polyvinyl acetalized composite fiber with improved resistance to hot water and repeated washing; the composite fiber of the present invention has excellent biological function and dyeability due to the high content of chitosan in the cortex, and due to the polyvinyl alcohol in the core layer The excellent fiber-forming performance and drawing performance of the ethylene component make the fiber obtain excellent physical and mechanical properties, and the production cost is low; it can be used as a textile raw material for disposable or medical purposes; after acetalization, it can be used to prepare various health-care products. Functional fabric.

Description

Chitosan and polyvinyl alcohol composite fiber and its manufacturing method

field of invention

The invention relates to a composite fiber of functional fiber material chitosan and polyvinyl alcohol and a manufacturing method thereof, in particular to chitosan and polyvinyl alcohol composite fiber with a skin-core structure and a manufacturing method thereof.

current technology

Chitosan is the product of deacetylation of chitin after concentrated alkali treatment. Chitin is a natural biopolymer extracted from shells of shrimps, crabs, insects, and cell walls of fungi and algae. In nature, the annual biosynthesis of chitin is more than 10 billion tons, and it is an extremely rich organic renewable resource second only to cellulose. Among the many natural polysaccharides, chitin and its main derivative chitosan are the only basic polysaccharides, which have many specific biological functions, such as high biocompatibility, broad-spectrum antibacterial activity, immune promotion activity, and promotion of epithelial cell growth And inhibit the growth of fibroblasts to promote healing and reduce scar performance, biodegradation and absorbability.

Existing technologies use chitin or chitosan solution to spin fibers for medical purposes such as absorbable surgical sutures and artificial skin, or for "transdermal action to activate cells, promote metabolism and enhance immunity, antibacterial detoxification, and weight loss. The "drug application principle" health care underwear for reducing fat and delaying aging. However, pure chitin or chitosan fibers lack the physical and mechanical properties required for post-textile processing, and are expensive and expensive, which limits their widespread application.

The existing technology adopts adding chitosan fine particles to the viscose spinning stock solution to spin antibacterial viscose fibers, but because the addition amount is very small (1-2% W/W), it cannot achieve the desired multiple biological functions .

JP0347,263[91 47,2633] discloses a method for manufacturing artificial hair by blending chitosan and polyvinyl alcohol, in which polyvinyl alcohol with a degree of alcoholysis of 98-99% is dissolved in water to obtain 15% polyvinyl alcohol Aqueous solution, low molecular weight chitosan is dissolved in 10% acetic acid aqueous solution to obtain 10% chitosan solution, the two solutions are blended at the ratio of polyvinyl alcohol solution/chitosan solution = 80/30 to obtain a blended spinning stock solution, which is sprayed Hole extrusion, Glauber's salt coagulation bath coagulation, drafting to obtain blended chitosan and polyvinyl alcohol composite fibers, and then through formalization process to obtain fibers for artificial hair. However, the strength of the blended chitosan and polyvinyl alcohol fibers obtained by this method is about 2 g/d, and when used in textile applications with finer deniers, it still cannot meet the requirements for the physical and mechanical properties of fibers in post-textile processing.

The existing technology of spinning polyvinyl formal fibers (being commonly called as vinylon or vinylon) is to adopt polyvinyl alcohol aqueous solution as the spinning stock solution, through wet forming (glauber's salt or sodium hydroxide aqueous solution coagulation bath) or dry forming (thermal Moisture in the air evaporates and solidifies), stretches to obtain polyvinyl alcohol fibers, and then obtains polyvinyl formal fiber vinylon through a formalization process. The main disadvantage of vinylon is poor dyeability, low dyeing amount and not bright color. Another disadvantage is that the elasticity is poor, and the pure fabric is easy to wrinkle, so it is mainly used for blending with cotton or wool. Its main advantages are high strength and good hygroscopicity. The performance and appearance of vinylon filament are very similar to natural silk, but it is difficult to be used as high-grade clothing because of its difficult dyeing and poor elasticity, and its use is limited. But on the other hand, polyvinyl alcohol is a synthetic polymer that can be independent of petroleum resources. It can produce acetylene by cracking methane in natural gas or biogas (produced by the decay of plants in stagnant water), and acetic acid can be produced by the reaction of acetylene and acetic acid. Ethylene and vinyl acetate are polymerized to obtain polyvinyl acetate, and polyvinyl acetate is alcoholyzed under the action of methanol and sodium hydroxide to obtain polyvinyl alcohol. Moreover, polyvinyl alcohol is a biodegradable polymer. When it is degraded, it first undergoes internal oxidation under the action of microorganisms to generate hydrogen peroxide and ketones, and then the ketones are further hydrolyzed, and finally metabolized by microorganisms into CO ₂ and H ₂ O (there are also literatures It is reported that under the action of certain strains, polyvinyl alcohol undergoes internal oxidation to generate alcohols instead of ketones). Therefore, polyvinyl alcohol is a synthetic polymer that meets the requirements of sustainable development and environmental protection.

content of the invention

The purpose of the present invention is to provide a composite fiber of chitosan and polyvinyl alcohol with naturally renewable raw materials and naturally degradable products. The composite fiber has a skin-core structure, has excellent physical and mechanical properties and dyeability, and has biological fiber The unique style and variety of biological health care and medical functions, the production cost.

Another object of the present invention is to provide a manufacturing method of chitosan and polyvinyl alcohol composite fibers with naturally renewable raw materials and naturally degradable products. The manufacturing method adopts the existing manufacturing method of skin-core structure composite fibers. Simple and suitable for large-scale industrial production.

In order to achieve the above object, the technical solution adopted in the present invention is: a composite fiber of chitosan and polyvinyl alcohol, which has a skin-core composite structure, the skin layer is chitosan, and the core layer is polyvinyl alcohol.

The technical solution adopted in the present invention may also be: a composite fiber of chitosan and polyvinyl alcohol, which has a skin-core composite structure, the skin layer is a mixture of chitosan and polyvinyl alcohol, and the core layer is polyvinyl alcohol.

Wherein, when the cortex is a mixture of chitosan and polyvinyl alcohol, the content of chitosan in the mixture of the cortex is greater than 0wt%-less than 100wt%, the rest is polyvinyl alcohol, and the core layer is polyvinyl alcohol; the chitosan In the composite fiber with polyvinyl alcohol, the content of chitosan is more than 0%-80wt% of the total fiber.

Preferably, in the skin layer, the content of chitosan is 20-60wt%, the rest is polyvinyl alcohol, and the core layer is polyvinyl alcohol; in the composite fiber of chitosan and polyvinyl alcohol, the content of chitosan is preferably 2% of the total amount of fiber 4-30wt%.

The chitosan has a molecular weight of 150,000-500,000, a degree of deacetylation of 70-90 percent; a degree of polymerization of polyvinyl alcohol of 1700-4000, and a degree of alcoholysis of 90-99 percent.

Further, the cortex of the present invention is acetalized; preferably, the cortex is acetalized with formaldehyde or glutaraldehyde.

The fineness of the chitosan and polyvinyl alcohol composite fiber of the invention is 2-7d, the breaking strength is 2.5-4.5g/d, and the breaking elongation is 10-20%.

The manufacturing method of chitosan and polyvinyl alcohol composite fiber of the present invention is: a kind of manufacturing method of chitosan and polyvinyl alcohol composite fiber, with polyvinyl alcohol spinning stock solution as core layer, with chitosan spinning stock solution or chitosan The blended spinning stock solution with polyvinyl alcohol is the skin layer, which is extruded from the sheath-core composite spinneret, formed by spinning, and then drawn and washed to obtain the chitosan-polyvinyl alcohol composite fiber with a skin-core structure.

The chitosan-polyvinyl alcohol composite fiber of the present invention can be formed by spinning after being extruded from a sheath-core composite spinneret assembly, and can adopt a wet spinning process, a dry-wet spinning process or a dry spinning process.

The chitosan and polyvinyl alcohol composite fiber and the manufacturing method thereof according to the present invention further include processing the composite fiber through an acetalization process to obtain chitosan and polyvinyl acetal with improved hot water resistance and repeated washing resistance Compound fibers; formaldehyde or glutaraldehyde is used for acetalization treatment.

The polyvinyl alcohol spinning stock solution of the present invention is an aqueous solution of polyvinyl alcohol or dilute acetic acid aqueous solution, and the concentration of the polyvinyl alcohol is 5-45 wt%, preferably 15-40 wt%. If it is a dilute acetic acid aqueous solution of polyvinyl alcohol, the polyvinyl alcohol is dissolved in an aqueous acetic acid solution whose concentration is below 3wt%, preferably below 2wt%, to obtain the spinning dope with the above-mentioned concentration of polyvinyl alcohol.

The chitosan spinning stock solution of the present invention is a dilute acetic acid aqueous solution of chitosan, and the chitosan concentration in the spinning stock solution is 2-10 wt%, preferably 5-8 wt%. The concentration of acetic acid in the dilute acetic acid aqueous solution in which chitosan is dissolved is 1-10 wt%, preferably 2-5 wt%.

The blended spinning stock solution of chitosan and polyvinyl alcohol in the present invention refers to the blended spinning stock solution obtained by mixing the chitosan spinning stock solution with the aforementioned polyvinyl alcohol spinning stock solution. The content of chitosan in the solid content of the blended spinning dope is more than 0 wt %-less than 100 wt %, preferably 20-60 wt %.

The polyvinyl alcohol spinning stock solution in the present invention refers to the spinning stock solution obtained by dissolving polyvinyl alcohol in water or dilute acetic acid aqueous solution at 89-99° C. and degassing. The concentration of acetic acid in the dilute acetic acid aqueous solution in which polyvinyl alcohol is dissolved is below 3wt%, preferably below 2wt%. The concentration of polyvinyl alcohol is 5-45wt%, preferably 15-40wt%. The chitosan spinning stock solution is configured to the required concentration as required, and the chitosan spinning stock solution is obtained by defoaming; the obtained chitosan spinning stock solution is mixed with the aforementioned polyvinyl alcohol spinning stock solution through a thermostat and a static mixer , that is, the blended spinning stock solution of chitosan and polyvinyl alcohol. When extruding through the skin-core type composite spinneret, the metering ratio of the two spinning dopes of the skin layer and the core layer at the inlet of the skin layer and the inlet of the core layer is determined according to the solid content weight ratio of the skin layer/core layer. Generally, the solid content of the skin layer/core layer The layer solid content is 10/90-80/20, preferably 20/80-50/50.

Specifically, the manufacturing method of the composite fiber of chitosan and polyvinyl alcohol described in the present invention is: dissolving polyvinyl alcohol in water or dilute acetic acid aqueous solution at 95-98°C to obtain polyvinyl alcohol with a concentration of 5-45wt%. Vinyl alcohol solution, after degassing to obtain polyvinyl alcohol spinning stock solution; dissolving chitosan in 1-10wt% dilute acetic acid aqueous solution at room temperature to obtain a chitosan solution with a concentration of 2-10wt%, and deaeration to obtain chitosan Spinning stock solution; the chitosan spinning stock solution is extruded from the dissolving kettle and then transported to the static mixer by the booster pump through the thermostat (temperature control 95-98°C), and the polyvinyl alcohol directly pumped to the static mixer The spinning stock solution is evenly mixed to obtain the blended spinning stock solution of chitosan and polyvinyl alcohol. The resulting chitosan spinning stock solution is extruded from the dissolving kettle and then sent to the cortex inlet metering pump by a booster pump through a thermostat (temperature control 95-98°C) and a pre-filter, or the obtained chitosan is mixed with polyvinyl alcohol The blended spinning stock solution enters the cortex inlet metering pump through the pre-filter, and the other polyvinyl alcohol spinning stock solution passes through the pre-filter pump to the core layer inlet metering pump. The speed of the metering pump at the cortex inlet/the speed of the metering pump at the core layer inlet is 1/0.50-1/1.5. The fine flow of composite stock solution extruded through the skin-core composite spinneret, and the fibers formed by wet, dry-wet or dry spinning are stretched 2-5.5 times under dry heat at 180-210°C to obtain the skin-core type Chitosan and polyvinyl alcohol composite fiber.

The wet method, or dry-wet method, or dry spinning forming of the present invention can adopt methods in the prior art. For example, during wet forming, the thin stream of composite stock solution extruded from the composite spinneret directly enters the coagulation bath, and the coagulant uses Glauber's salt (saturated Na ₂ SO ₄ ) aqueous solution or NaOH aqueous solution spun by vinylon; during dry and wet forming, the composite The original solution flows through a 1-10cm air gap and then enters the coagulation bath; during dry forming, the composite original solution flows through a hot air tunnel at 100-170°C to volatilize the solvent and solidify.

Whether the skin-core type chitosan and polyvinyl alcohol fiber of the present invention adopts the acetalization treatment process depends on the final product use. When used for disposable or medical purposes, acetalization is not required. When used in hot water resistance or multiple washing applications, acetalization is required.

The sheath-core type chitosan and polyvinyl alcohol composite fiber manufactured according to the above method has excellent biological function and dyeability due to the high content of chitosan in the fiber cortex; Low production cost; due to the excellent fiber-forming performance and drawing performance of the polyvinyl alcohol component in the core layer, the fiber obtains excellent physical and mechanical properties. The composite fiber of the invention can be used as a textile raw material for disposable or medical purposes; after acetalization, the hot water resistance and repeated washing performance are improved, and can be used for preparing various fabrics with health care functions.

Detailed ways

The following are specific examples of the present invention, and the described examples are used to describe the present invention rather than limit the present invention. Unless otherwise specified, the solution concentration in the examples is the average weight percentage.

Example 1

Dissolve polyvinyl alcohol (polymerization degree 1750, alcoholysis degree 99%) in 2wt% dilute acetic acid aqueous solution at 95-98°C to obtain a polyvinyl alcohol solution with a concentration of 15wt%, and obtain polyvinyl alcohol spinning through deaeration stock solution. Dissolve chitosan (molecular weight: 200,000, degree of deacetylation: 80%) in 2 wt% dilute acetic acid aqueous solution at room temperature to obtain a chitosan solution with a concentration of 7.5 wt%, and obtain a chitosan spinning stock solution after degassing. The chitosan spinning stock solution is extruded from the dissolving kettle, and is transported to the static mixer by the booster pump through the thermostat (temperature control 95-98°C), and is evenly mixed with the polyvinyl alcohol spinning stock solution that is directly pumped to the static mixer. Mixing, the mixing ratio of chitosan stock solution/polyvinyl alcohol stock solution is 1/0.75 (V/V), and then enters the cortex inlet metering pump through the pre-filter, and the other polyvinyl alcohol spinning stock solution is directly pumped to the core layer through the pre-filter Inlet metering pump. Cortex inlet metering pump speed/core layer inlet metering pump speed is 1/1.32. The thin stream of the composite stock solution extruded through the skin-core composite spinneret directly enters the coagulation bath of a nearly saturated aqueous sodium sulfate solution (410 g/L) at 45°C, and is stretched 2.5 times after being solidified in the coagulation bath, and then heated in an aqueous solution of sodium sulfate at 90°C (370 grams per liter) in drafting 1.7 times, wash, dry and stretch 1.5 times under dry heat at 210 ℃, obtain sheath-core type chitosan and polyvinyl alcohol composite fiber, the content of chitosan in the cortex is 40wt%, The content of chitosan is 14wt% of the total amount of fiber, the fineness of the fiber is 6.2d, the strength is 3.1g/d, and the elongation at break is 15%.

Example 2

Others are the same as Example 1, but the difference is that the thin stream of the composite stock solution extruded through the skin core type composite spinneret directly enters the 30wt% NaOH aqueous solution coagulation bath, stretches 3 times after coagulation bath coagulation, then at 90 ℃ 20wt% It was stretched 2.2 times in a sodium hydroxide aqueous solution, washed and dried, and stretched 1.8 times under dry heat at 210°C to obtain a sheath-core chitosan-polyvinyl alcohol composite fiber with a fineness of 3.9d and a strength of 4.2g/d , Elongation at break of 13%.

Example 3

Polyvinyl alcohol (polymerization degree 1750, alcoholysis degree 99%) is dissolved in water at 95-98° C. to obtain a polyvinyl alcohol solution with a concentration of 45 wt%, and the polyvinyl alcohol spinning stock solution is obtained through defoaming. Dissolve chitosan (molecular weight: 150,000, degree of deacetylation: 85%) in 10 wt% dilute acetic acid aqueous solution at room temperature to obtain a chitosan solution with a concentration of 10 wt%, and obtain a chitosan spinning stock solution after degassing. The chitosan spinning stock solution is extruded from the dissolving kettle, and then is transported to the static mixer by the booster pump through the thermostat (temperature control 95-98°C), and spun with 45wt% polyvinyl alcohol directly pumped to the static mixer. The stock solution is evenly mixed, the mixing ratio of chitosan stock solution/polyvinyl alcohol stock solution is 1/0.6 (V/V), and then enters the cortex inlet metering pump through the pre-filter, and the other 45wt% is directly pumped to the core layer inlet metering through the pre-filter Pump. Cortex inlet metering pump speed/core layer inlet metering pump speed is 1/1.16. The fine flow of the composite raw liquid extruded through the skin-core composite spinneret is stretched through a 5cm air gap nozzle and then enters a coagulation bath of a nearly saturated aqueous sodium sulfate solution (410 g/L) at 45 ° C. After being solidified in the coagulation bath, it is stretched twice. Then draw 2.1 times in sodium sulfate aqueous solution (370 g/L) at 90°C, wash and dry, and stretch 1.6 times under dry heat at 210°C to obtain sheath-core chitosan and polyvinyl alcohol composite fibers, with carapace in the cortex The content of amine is 27wt%, the content of chitosan is 8wt% of the total fiber, the fineness of the fiber is 4.3d, the strength is 3.6g/d, and the elongation at break is 17%.

Example 4

Polyvinyl alcohol (polymerization degree 1750, alcoholysis degree 99%) is dissolved in water at 95-98° C. to obtain a polyvinyl alcohol solution with a concentration of 38 wt%, and the polyvinyl alcohol spinning stock solution is obtained through defoaming. Dissolve chitosan (molecular weight: 300,000, degree of deacetylation: 75%) in 2 wt% dilute acetic acid aqueous solution at room temperature to obtain a chitosan solution with a concentration of 5 wt%, and obtain a chitosan spinning stock solution after defoaming. The chitosan spinning stock solution is extruded from the dissolving kettle, and is delivered to the cortex inlet metering pump by the booster pump through the thermostat (temperature control 95-98°C), the pre-filter, and the other 38wt% polyvinyl alcohol spinning stock solution Pump through the pre-filter to the core layer inlet metering pump. The speed of the metering pump at the cortex inlet/the speed of the metering pump at the core layer is 1/0.53. The composite stock solution extruded through the skin-core composite spinneret flows through a 6.7-meter dry-process tunnel at 150°C for solvent volatilization and solidification, and the cured fibers are stretched 5.2 times under dry heat at 180°C to obtain skin-core chitosan and Polyvinyl alcohol composite fiber; the content of chitosan in the cortex is 100wt%, the content of chitosan is 20wt% of the total fiber, the fiber has a fineness of 3.1d, a strength of 3.2g/d, and an elongation at break of 20%.

Example 5

Others are the same as in Example 4, except that the obtained sheath-core type chitosan and polyvinyl alcohol composite fiber are placed in an aqueous solution of glutaraldehyde (32 g/liter), reacted at room temperature for 2 hours, then taken out, washed and dried to obtain the carapace Amine and polyvinyl glutaraldehyde composite fiber, the strength of the fiber is 3.9g/d, the elongation at break is 12%, and the hot water resistance is significantly improved.

Example 6

Others are the same as Example 2, but the difference is that the resulting chitosan and polyvinyl alcohol composite fiber is placed in an aldehyde composed of formaldehyde (25 g/liter), sulfuric acid (225 g/liter), sodium sulfate (70 g/liter) Take it out after reacting in a chemical bath at 70°C for 30 minutes, wash and dry to obtain chitosan-polyvinyl formal composite fiber, the fiber strength is 3.9g/d, the elongation at break is 12%, and the hot water resistance is significantly improved.

Example 7

Others are the same as Example 1, except that polyvinyl alcohol (2400 degree of polymerization, 98% degree of alcoholysis) is dissolved in the dilute acetic acid of 3wt%, obtains the concentration of 30wt% of polyvinyl alcohol spinning stock solution, and chitosan (molecular weight 50% 10, deacetylation degree 70%) is dissolved in 1wt% dilute acetic acid aqueous solution at room temperature, obtains the chitosan solution that concentration is 2wt%, the content of chitosan in the cortex of product chitosan and polyvinyl alcohol composite fiber is 8wt%, The content of chitosan is 2wt% of the total amount of fibers. The fineness of the fiber is 2.1d, the strength is 4.2g/d, and the elongation at break is 18%.

Example 8

Others are the same as Example 4, except that polyvinyl alcohol (polymerization degree 4000, alcoholysis degree 92%) is dissolved in water to obtain polyvinyl alcohol spinning stock solution concentration 5wt%, and chitosan (molecular weight 150,000, deacetylation degree 90%) was dissolved in 1wt% dilute acetic acid aqueous solution at room temperature to obtain a chitosan solution with a concentration of 10wt%. The content of chitosan in the cortex of the product chitosan and polyvinyl alcohol composite fiber was 100wt%. 79wt% of the total. The fineness of the fiber is 2.8d, the strength is 2.6g/d, and the elongation at break is 11%.

Example 9

Others are the same as Example 1, the difference is that the concentration of polyvinyl alcohol spinning stock solution is 30wt%, the concentration of chitosan solution is 2wt%, and the mixing ratio of appropriate chitosan stock solution/polyvinyl alcohol stock solution and the rotating speed of the cortical inlet metering pump/ The speed ratio of the metering pump at the inlet of the core layer, the chitosan content in the cortex of the product chitosan and polyvinyl alcohol composite fiber is 1wt%, and the chitosan content is 0.1wt% of the total fiber amount. The fineness of the fiber is 2.2d, the strength is 4.5g/d, and the elongation at break is 20%.

Example 10

Others are the same as Example 1, the difference is that the concentration of polyvinyl alcohol spinning stock solution is 30wt%, the concentration of chitosan solution is 4wt%, and the mixing ratio of appropriate chitosan stock solution/polyvinyl alcohol stock solution and the speed of the metering pump at the entrance of the cortex/ The speed ratio of the metering pump at the inlet of the core layer, the content of chitosan in the cortex of the product chitosan and polyvinyl alcohol composite fiber is 20wt%, and the content of chitosan is 6wt% of the total fiber amount. The fineness of the fiber was 4.9d, the strength was 4.0g/d, and the elongation at break was 15%.

Example 11

Others are the same as Example 1, the difference is that the concentration of polyvinyl alcohol spinning stock solution is 20wt%, the concentration of chitosan solution is 6wt%, and the mixing ratio of appropriate chitosan stock solution/polyvinyl alcohol stock solution and the rotating speed of the cortical inlet metering pump/ The speed ratio of the metering pump at the inlet of the core layer, the content of chitosan in the cortex of the product chitosan and polyvinyl alcohol composite fiber is 60wt%, and the content of chitosan is 10wt% of the total fiber amount. The fineness of the fiber is 5.5d, the strength is 3.5g/d, and the elongation at break is 18%.

Claims (15)

1. A chitosan and polyvinyl alcohol composite fiber has a skin-core type composite structure, the cortex is chitosan, and the core layer is polyvinyl alcohol. 2. A composite fiber of chitosan and polyvinyl alcohol, which has a skin-core composite structure, the skin layer is a mixture of chitosan and polyvinyl alcohol, and the core layer is polyvinyl alcohol. 3. The composite fiber of chitosan and polyvinyl alcohol according to claim 2, wherein the content of chitosan in the mixture of chitosan and polyvinyl alcohol in the cortex is greater than 0wt%-less than 100wt%, and all the other are polyvinyl alcohol, The core layer is polyvinyl alcohol. 4. The chitosan-polyvinyl alcohol composite fiber according to claim 1 or 2, wherein in the chitosan-polyvinyl alcohol composite fiber, the content of chitosan is greater than 0wt% and less than 80wt% of the total amount of fibers. 5. The composite fiber of chitosan and polyvinyl alcohol according to claim 2, the skin layer is 20-60wt% chitosan, the rest is polyvinyl alcohol, and the core layer is polyvinyl alcohol. 6. The composite fiber of chitosan and polyvinyl alcohol according to claim 5, wherein the content of chitosan is 4-30wt% of the total amount of fiber. 7. The chitosan-polyvinyl alcohol composite fiber according to claim 1 or 2, wherein said fiber is acetalized fiber. 8. The composite fiber of chitosan and polyvinyl alcohol according to claim 7, wherein the fiber is acetalized with formaldehyde or glutaraldehyde. 9. a kind of chitosan and polyvinyl alcohol composite fiber according to claim 1 or 2, the molecular weight of described chitosan is 150,000-500,000, and the deacetylation degree is 70-90%; The polymerization degree of polyvinyl alcohol is 1700-4000, the degree of alcoholysis is 90-99%; the fineness of the composite fiber is 2-7d, the breaking strength is 2.5-4.5g/d, and the breaking elongation is 10-20%. 10. the manufacture method of a kind of chitosan and polyvinyl alcohol composite fiber described in claim 1 or 2, take polyvinyl alcohol spinning stock solution as core layer, take the blending spinning stock solution of chitosan or chitosan and polyvinyl alcohol as The cortex is extruded from the skin-core composite spinneret, formed by spinning, and then drawn and washed to obtain chitosan-polyvinyl alcohol composite fibers with a skin-core structure. 11. The manufacturing method of a chitosan-polyvinyl alcohol composite fiber according to claim 10, dissolving polyvinyl alcohol with a degree of polymerization of 1700-4000 and a degree of alcoholysis of 90-99% at 95-98°C In water or dilute acetic acid aqueous solution below 3wt%, obtain a polyvinyl alcohol solution with a concentration of 5-45wt%, and obtain a polyvinyl alcohol spinning stock solution through defoaming; the molecular weight is 150,000-500,000, and the degree of deacetylation is 70- 90% of chitosan is dissolved in 1-10wt% dilute acetic acid aqueous solution at room temperature to obtain a chitosan solution with a concentration of 2-10wt%, and the chitosan spinning stock solution is obtained by defoaming; the chitosan spinning stock solution is self-dissolving After the middle pressure is discharged, the booster pump is transported to the static mixer through the thermostat whose temperature is controlled at 95-98°C, and is evenly mixed with the polyethylene spinning stock solution directly pumped to the static mixer to obtain chitosan and polyvinyl alcohol. The blended spinning stock solution; after the chitosan spinning stock solution is extruded from the dissolving tank, it is transported to the cortex inlet metering pump by the booster pump through a thermostat and a pre-filter whose temperature is controlled at 95-98°C, or The resulting blended spinning stock solution of chitosan and polyvinyl alcohol enters the cortex inlet metering pump through the pre-filter, and the other polyvinyl alcohol spinning stock solution passes through the pre-filter pump to the core layer inlet metering pump, and the cortex inlet metering pump speed/core layer The speed of the inlet metering pump is 1/0.50-1/1.5, and the fine flow of the composite stock solution extruded through the skin-core composite spinneret is stretched 2-5.5 times by dry heat at 180-210°C. The composite fiber of skin-core chitosan and polyvinyl alcohol was obtained. 12. The manufacturing method of a kind of chitosan and polyvinyl alcohol composite fiber according to claim 11, wherein said chitosan and polyvinyl alcohol composite fiber are formed by spinning after being extruded from sheath-core type composite spinneret assembly , can be formed by wet method, dry-wet method or dry spinning process; The wet forming method is that the thin stream of the composite stock solution extruded from the composite spinneret directly enters the coagulation bath, and the coagulant is saturated _Na2SO4 aqueous solution or NaOH aqueous solution of vinylon spinning _; The dry-wet method is formed as follows: the composite stock solution flows through an air gap of 1-10 cm and then enters the coagulation bath; The dry forming method is as follows: the composite stock solution flows through a hot air tunnel at 100-170° C. to volatilize the solvent and solidify. 13. The manufacturing method of a chitosan-polyvinyl alcohol composite fiber according to claim 10 or 11, wherein the chitosan-polyvinyl alcohol composite fiber is further subjected to acetalization treatment. 14. The manufacturing method of a kind of chitosan and polyvinyl alcohol composite fiber according to claim 13, wherein said acetalization treatment adopts formaldehyde or glutaraldehyde. 15. The manufacture method of a kind of chitosan and polyvinyl alcohol composite fiber according to claim 14, wherein said acetalization treatment is: placing sheath-core type chitosan and polyvinyl alcohol composite fiber in formaldehyde-containing or In the hydroformylation bath of glutaraldehyde, react at room temperature -70°C for 0.5-2 hours, take it out, wash and dry to obtain chitosan-polyvinyl acetalized composite fiber.