JPS5822047B2 - Method for manufacturing insoluble polymer molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing an insoluble polymer molded article.

More specifically, the purpose is to provide a new method for easily and inexpensively producing insoluble polymer molded articles from chitosan obtained by hydrolyzing chitin or its analogues (hereinafter referred to as chitin hydrolysis products). .

The above-mentioned chitin is a natural polymer whose main constituent unit is N-acetyl-D-glucosamine, which is widely distributed in nature and is relatively abundant as a resource.

Molded products made from chitin or its derivatives have attracted attention in recent years as functional materials that are non-toxic and biodegradable. Because chitin is insoluble and infusible in other common solvents, it is difficult to obtain molded products such as threads or films from chitin itself, and molded products made from chitin's soluble derivatives, such as chitosan, are difficult to obtain. In general, there are problems such as poor water resistance, and furthermore, it is difficult to make chitin derivatives other than chitosan due to the insolubility of chitin mentioned above, so various types are still being studied. be.

In consideration of the above-mentioned problems, the present inventors conducted repeated research to obtain insoluble molded products using chitin hydrolysis products as raw materials, and as a result, the present inventors discovered previously that chitin hydrolysis products By applying carbamoylation reaction,
The present invention was accomplished by discovering a method for easily producing insoluble molded articles from a hydrolyzed product of chitin, which is relatively easy to obtain among chitin derivatives.

That is, the present invention provides (1) a molded article made of a hydrolyzed product of chitin with monofunctional cyanic acid or isocyanic acid or their salts, or with urea, biuret, or triuret that produces monofunctional isocyanic acid by heating. (2) a method for producing an insoluble polymer molded article, characterized in that it is treated with a chitin hydrolysis product (
a), and monofunctional cyanic acid or isocyanic acid or their salts, or urea, biuret or triuret that produces monofunctional isocyanic acid by heating (
This is a method for producing an insoluble polymer*, which is characterized in that the composition containing b) is molded and then heated if necessary.

The present invention will be explained in detail below.

The basis of the method of the present invention is the carbamoylation reaction illustrated below.

More specifically, the product obtained by this reaction is insoluble in water, general organic solvents, and alkalis, and is soluble in dilute acids with a low degree of carbamoylation, but with a low degree of carbamoylation, Those with a certain degree of carbamoylation will swell but will be insoluble, and those with a high degree of carbamoylation will be insoluble and have a considerably low swelling property.

Therefore, for example, a molded article made of a chitin hydrolysis product is prepared in advance and then carbamoylated by an appropriate method, or a carbamoylating agent is added to an acid solution of the chitin hydrolysis product. An insoluble molded product can be easily obtained by a method such as molding this into a film or the like.

Next, the method of the present invention will be specifically described.

There is no particular restriction on the degree of polymerization of the chitin hydrolysis product used in the present invention, and the degree of deacetylation does not necessarily have to be completely deacetylated. It doesn't matter if it remains.

Preferably, the degree of deacetylation is around 80% and the concentration is 1%,
Viscosity in aqueous solution with acetic acid concentration of 1% is 10-2000c
Something around ps is good.

In order to obtain an insoluble molded article from the above-mentioned chitin hydrolysis product, a molded article made of the chitin hydrolysis product or its acid salt is prepared in advance by a conventionally known method, and the molded article is brought into contact with a carbamoylating agent. It is preferable to insolubilize it by allowing it to dissolve.

The acid used in the present invention may be either an organic acid such as formic acid or acetic acid or an inorganic acid such as hydrochloric acid or nitric acid, but acetic acid is particularly preferred.

The above-mentioned carbamoylating agent that characterizes the method of the present invention is monofunctional cyanic acid or isocyanic acid or salts thereof, or urea, biuret, triuret, etc. that produce monofunctional isocyanic acid by heating. Among these, salts such as sodium isocyanate are particularly preferred.

In order to carry out a reaction by bringing these salts into contact with a molded product made of a hydrolysis product of chitin or an acid salt thereof, it is preferable to immerse the molded product in an aqueous solution of the salts, and then add an acid thereto to allow the reaction to proceed. It is.

In this case, an organic solvent such as methanol or acetone may be added to prevent the molded product from swelling more than necessary at the initial stage of the reaction in the carbamoy carbonizing agent aqueous solution.

The reaction temperature is preferably about 0 to 100°C, and the insolubilized product can be obtained in about 1 to 24 hours, although the reaction time depends on other conditions.

The amount of carbamoylating agent used varies depending on the properties required of the desired molded product.

That is, if the desired product is required to have sufficient water resistance, the carbamoylating agent should be used in an amount equal to or more than the equivalent of the amine group in the chitin hydrolysis product that is the raw material.

In addition, if the target product is required to have a certain degree of hydrophilicity such as water swelling property, it is possible to use a carbamoylating agent in an amount less than the equivalent of the amine group, or to adjust the reaction conditions. You can reach your goal.

The carbamoylating agent is suitably applied as an aqueous solution as described above, but in some cases it is also possible to apply the carbamoylating agent as a vapor.

Furthermore, in the present invention, various additives such as natural or synthetic resins, plasticizers, various coloring agents, various fillers, etc. are added to the chitin hydrolyzed product, and this is molded to carry out the present invention. Of course, it is also possible.

The molded product obtained by the above method is insoluble in water, general organic solvents, alkalis and dilute acids, and particularly those that are highly carbamoylated have a low degree of swelling and sufficient strength even when wet.

Moreover, this material is non-toxic and has good microbial degradability and semipermeability.

For these reasons, the insoluble molded product obtained by the method of the present invention can be used in a wide range of applications such as various packaging films, disposable films, semipermeable membranes, coatings, medical materials, fibers, and others.

This will be explained in detail below using examples.

All percentages in the text are based on weight.

As a hydrolysis product of chitin, deacetylation degree is 8
0-85% chitosan was used.

Example 1 A chitosan acetate aqueous solution having a chitosan concentration of 2% and an acetic acid concentration of 1% was cast onto a glass plate and dried at 25° C. for 24 hours to obtain a chitosan acetate film.

This film was immersed in a 2% sodium isocyanate aqueous solution at 25°C, and after 1 hour, acetic acid was added dropwise to the solution to adjust the pH of the solution to about 8, and the film was left to stand for 3 hours.

Next, in order to prevent excess sodium isocyanate from remaining in the film, acetic acid was further added to bring the pH of the solution to about 4, and after leaving it for 3 hours, the film was taken out and washed with a dilute aqueous sodium carbonate solution and then with water. Obtained the object.

This film was insoluble in water, common organic solvents, alkalis, and dilute acids, was transparent, had sufficient strength, and showed almost no decrease in strength even when wet.

This material is non-toxic and has good microbial degradability.
It was suitable as a disposable film.

Example 2 A fibrous product was obtained by extruding a chitosan acetate aqueous solution having a chitosan concentration of 1% and an acetic acid concentration of 1% into acetone using a spinning machine.

This fibrous material was treated in the same manner as in Example 1 to make it insolubilized.

The resulting fibrous material was white and insoluble in water, common organic solvents, alkalis, and dilute acids.

This material was non-toxic and had sufficient strength even when wet, and was suitable as a gauze thread.

Example 3 A chitosan acetate aqueous solution with a chitosan concentration of 2%, acetic acid concentration of 1%, and urea concentration of 1% was poured into a glass mold, and water was evaporated to obtain a milky white film with a thickness of about 0.5 mm. .

This film is mostly soluble in water, but when this film is heat-treated at 120°C to 130°C for 30 minutes, it becomes translucent and insoluble in water and dilute acids, and has sufficient water resistance and sufficient physical strength. , had degrees.

This film is sufficiently stable in air, but easily disintegrated by microorganisms in soil, making it useful for a variety of disposable applications.

Claims (1)

[Scope of Claims] 1. A molded article made of a chitin hydrolysis product is treated with monofunctional cyanic acid or isocyanic acid or their salts, or with urea, biuret, or triuret that produces monofunctional isocyanic acid by heating. A method for producing an insoluble polymer molded article. 2 Molding a composition containing a hydrolysis product of chitin (a) and monofunctional cyanic acid or isocyanic acid or salts thereof, or urea, biuret, or triuret (b) that produces monofunctional isocyanic acid by heating. A method for producing an insoluble polymer molded article, the method comprising heating as necessary.