JP2615038B2 - Method for producing chitin molded article - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a chitin molded article, and more particularly, to a method for producing a chitin molded article suitable for producing a contact lens or the like which is required to have high transparency. It relates to a manufacturing method.

(Prior Art) Many coagulants are known for obtaining a molded article from a chitin solution. For example, JP-A-51-13367 discloses acetone, coagulant for chitin dissolved in trichloroacetic acid or dichloroacetic acid and halogenated hydrocarbon, and acetone.
It describes aliphatic ketones such as methyl ethyl ketone, chlorinated aliphatic hydrocarbons such as carbon tetrachloride and trichloroethylene, hydrocarbons such as cyclohexane and hexane, and alcohols such as ethyl alcohol and isopropyl alcohol. Further, JP-A-52-100499 discloses ketones or alcohols such as acetone, methyl ethyl ketone, methanol, ethanol, propanol or butanol as coagulants for chitin dissolved in dimethylacetamide or N-methylpyrrolidone containing a small amount of lithium chloride. Have been described.

(Problems to be Solved by the Invention) However, such a coagulant is useful for producing a molded article having a relatively small diameter or thickness such as a fiber or a film, but has a large thickness and a particularly high transparency. When a molded article such as a contact lens is required to have high transparency, for example, it has a drawback that sufficient transparency cannot be obtained, and it is difficult to completely remove a solvent. Not something.

An object of the present invention is to provide a method for producing a chitin molded article having excellent transparency. It is another object of the present invention to provide a method for producing a chitin molded article in which no solvent remains in the molded article.

(Means for Solving the Problems) The inventors of the present invention have conducted intensive studies to achieve the above-mentioned objects, and as a result, when dimethylformamide is used as a coagulant when wet-forming a solution of chitin or a chitin derivative. As a result, the present inventors have found that the above-mentioned object can be achieved, and arrived at the present invention.

That is, the gist of the present invention is a method for producing a chitin molded body, which comprises using dimethylformamide as a coagulant when coagulating a solution of chitin or a chitin derivative to produce a molded body.

In the present invention, chitin refers to poly (N-acetyl-) obtained by treating crustaceans, insects and the like with hydrochloric acid and caustic soda to remove proteins and calcium.
D-glycosamine). Examples of the chitin derivative include so-called chitosan in which a part of the acetylamino group of chitin is deacetylated, etherified products, esterified products, hydroxyethylated products, O-ethylated products, and specific examples thereof include poly [N -Acetyl-6-O-
(2-hydroxyethyl) -D-glycosamine], poly [N-acetyl-6-O- (ethyl) -D-glucosamine] and the like.

As a solvent for dissolving these into a solution, in the case of chitin having a large amount of acetylglucosamine groups, for example, a mixture of trichloroacetic acid and a halogenated hydrocarbon, a mixture of lithium chloride and dimethylacetamide,
Alternatively, a mixture of lithium chloride and N-methylpyrrolidone can be preferably used. On the other hand, in the case of chitosan having many glucosamine groups, an acid aqueous solution such as acetic acid can be preferably used. Two
It is preferred to make a 0 wt% chitin dope.

The method of the present invention is particularly useful when processing these solutions into molded articles such as films, lenses, plates, cylinders, fibers, etc., especially when the molded articles have a large thickness or diameter, for example, thickness or diameter. Is useful when producing a molded article having a diameter of 0.1 mm or more.

In the present invention, dimethylformamide is used as a coagulant. However, these do not impair the purpose of the present invention, and may contain other organic solvents such as alcohols, ketones and ethers in a small amount, preferably 10 v / v. v% or less may be contained.

As a method of coagulating the chitin solution, an ordinary method of immersing the chitin solution in a coagulant can be adopted, but the method is not particularly limited. The solidification temperature is preferably 100 ° C. or less, particularly preferably 50 ° C. or less. The preferred solidification time varies depending on the size and thickness of the molded product to be produced, but is preferably 2 hours or more when a relatively thick molded product such as a molded product having a thickness of 0.1 mm or more is produced. Further, in the present invention, after coagulation, the coagulant can be replaced with another organic solvent to facilitate drying.

For example, when a contact lens is manufactured by the method of the present invention, it is preferable that the process from solidification to drying is performed under a fixed length, and the following method can be employed.

First, the chitin dope may be continuously applied to the outer peripheral portion of the solid without any break, immersed in a coagulant, coagulated, and dried as it is. In this case, the coagulated material shrinks as the coagulation proceeds, and as a result, the coagulated material is not separated from the outer periphery of the solid, but remains on the surface, that is, from solidification to drying under a fixed length. Is performed.
As the solid material, any shape such as a sphere, a rod, a column, a polygon, and the like can be used, and any material may be used as long as it is an inorganic or organic material such as metal, glass, plastic, and wood. . It is particularly preferable that the surface of the solid is smooth and has the same shape as the inside of the lens to be formed.

To apply the chitin dope to the outer periphery of such a solid material, the viscosity of the chitin dope itself may be used. For example, when the solid material is a cylindrical shape, the cylindrical shape may be replaced with a larger-diameter tubular material. The chitin dope may be inserted into the gap between the outside of the cylinder and the inner wall of the tube. The thickness of the chitin dope applied to the outer peripheral portion varies depending on the concentration of the chitin dope and the thickness of the contact lens material to be obtained.
1 ~ 50mm, more preferably 1 ~ 30mm, optimally 2 ~ 20mm
Range.

The chitin dope applied as described above is brought into contact with a coagulant to coagulate, and the temperature of the coagulant is preferably in the range of 0 to 100 ° C. The bath ratio is preferably at least 5 times the capacity of the chitin dope. By bringing the chitin dope into contact with the coagulant in this way, a coagulated substance adhered to the outer periphery of the solid substance is obtained.

The coagulated material may be washed by an organic solvent treatment or a hot water treatment other than the used coagulant, if necessary.

Drying may be performed while the solidified matter is attached to the outer periphery of the solid matter. Thus, a chitin molded body suitable as a contact lens material is obtained. As a drying method,
Natural drying, hot air drying, vacuum drying, etc. can be adopted. The drying temperature is preferably in the range of 0 to 120 ° C. Further, it is preferable that after drying, treatment with water or a low-boiling compound such as alcohol is performed to completely remove the remaining solvent or coagulant.

EXAMPLES Next, the present invention will be described more specifically with reference to examples.

Example 1 and Comparative Example 2 8 g of chitin powder (manufactured by Shin Nippon Chemical) was dissolved at room temperature in 92 g of N-methylpyrrolidone containing 8 W / W% lithium chloride.
A chitin dope was obtained. This chitin dope is applied on the outer surface of a glass tube with a diameter of about 10 cm to a thickness of about 10 mm with a width of 10 cm, at 25 ° C.
Was immersed in 500 cc of dimethylformamide for solidification. After being left overnight at room temperature, it was vacuum dried for about 6 hours. Then, wash with warm water of 80 ° C for 30 minutes,
After air drying for 2 hours, vacuum drying was performed for 2 hours, and then peeled off from the glass tube. The contact lens material thus obtained has an average thickness of 3.8 mm, and the wet strength and the visible light transmittance when wet are 2660 g / mm ² and 70.5 (400 nm) to 90.5, respectively.
3.4 (800 nm)%.

The lens material was cut and polished in consideration of the swelling ratio (72%) when containing water to obtain a lens.

The obtained lens has wet strength and visible light transmittance of 2140 g / mm ² and 81.7 (400 nm) to 99.9 (80 nm, respectively).
0 nm)%, which was suitable for use as a contact lens.

For comparison, solidification was carried out in the same manner as in Example 1 except that it was immersed in water instead of dimethylformamide. During the solidification, the molded body had already been devitrified and was not in a state usable as a contact lens. .

(Effect of the Invention) According to the method of the present invention, it is possible to produce a chitin molded article having a high transparency and a small amount of residual solvent. Therefore, the present invention is particularly useful for producing a highly transparent contact lens. is there.

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Claims (1)

(57) [Claims] 1. A method for producing a chitin molded article, comprising using dimethylformamide as a coagulant when coagulating a solution of chitin or a chitin derivative to produce a molded article.