JPH02180903A - Crosslinked chitosan - Google Patents

Abstract

PURPOSE:To obtain a crosslinked chitosan improved in flexibility and heat resistance by crosslinking chitosan by reaction with a specified N- hydroxyimidoester compound. CONSTITUTION:1-10wt.% chitosan (a) of a degree of deacetylation of chitin of 40-100% is dissolved in a dilute aqueous solution whose acidity is adjusted to a pH of 4-5 with, e.g. hydrochloric acid. An N-hydroxylimidoester compound (b) of formula I (wherein X is a residue of a 2-6C compound of 2-6 OH groups; A is an oxyethylene or the like; Y is a residue of a dibasic acid such as oxalic acid; Z is a group selected from among groups of formulas II-VIII and partially substituted derivatives thereof; m is 1-500; and n is 2-6) is mixed with the above solution in an (a) to (b) ratio by weight of 100/(1-50), and the mixture is agitated at 20-30 deg.C for about 5min at 1000-2000rpm and left standing at 40-60 deg.C for 2-3hr.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to crosslinked chitosan obtained by reacting chitosan and an N-hydroxyimide ester compound.

[Prior Art] Chitosan is a type of polysaccharide obtained by deacetylating chitin (mostly collected from the shells of crustaceans such as crabs) and has many amino groups in its molecule.

Chitosan is known to have properties such as being soluble in dilute acid aqueous solutions, having excellent ecological compatibility and biodegradability, being water retentive, and being low in calories. Utilizing these properties, it has already been put into practical use as a cationic flocculant and filtration agent in wastewater treatment, and is also being widely studied in fields such as pharmaceuticals such as artificial skin, as well as cosmetics and foods. ing.

[Problems to be solved by the invention] However, chitosan cannot be said to be fully utilized effectively because it does not dissolve in anything other than dilute acids, and its physical properties are rigid and lack flexibility. is the current situation.

The purpose of the present invention is to provide a material that can be used in a wider range of applications by making use of the advantages of chitosan described above while imparting flexibility and stability against heat and chemicals.

[Means for Solving the Problems] The present invention is a crosslinked chitosan obtained by reacting chitosan with an N-hydroxyimide ester compound represented by the general formula [I].

A is one or more mixed groups selected from oxyethylene group, oxypropylene group and oxybutylene group, Y is a dibasic acid residue, Z is and a partially substituted product thereof, and a partially substituted product thereof.

vinegar (However, during the ceremony.

X is a residue of a compound having 2 to 6 carbon atoms and 2 to 6 hydroxyl groups, and a partially substituted product thereof, (4) Formula [■Coゝ”CI( and H / and a partially substituted product thereof, 5) Formula [■ko\H2 /CI-(・ and its partially substituted product, (6) Formula [X1fl] \ l12 Electron CI-I 2 [ /CI(・ and its partially substituted product, 111 is a group selected from 1-5
00, fl indicates 2-6. ) The chitosan used in the present invention is a deacetylated form of chitin, which is a polysaccharide in which glucosamine is bonded to β-1,4 type (1
, 4)-2-amino-2deoxy-β-D-glucosamine.

Chitin is N-acetylated and glucosamine is β-1,4
It is expressed by the general formula [LX].

and partially substituted products thereof, and (7) formula [■ko\CI-(H[7buII- (in the formula, p is 10 to 500). 100%, preferably 70 to 100% chitosan PSH [trade name of Yaizu Suisan Co., Ltd., deacetylation degree 8] can be used.
5% or more.

The N-hydroxyimide ester compound used in the present invention is used as a crosslinking agent, and is represented by the general formula [I
] (hereinafter referred to as a crosslinking agent).

In general formula [I], X has 2 to 6 carbon atoms, and 2 to 6
Compounds with hydroxyl groups, such as ethylene glycol,
An alcohol residue derived from propylene glycol, glycerin, diglycerin, trimethylolethane, trimethylolpropane, pentaerythritol, erythritol, sorbitol, mannitol, glucose, mannose, xylose, sorbitan, etc., and n is one of these alcohols. It shows a value of 2 to 6 corresponding to the hydroxyl group.

A is one type or a mixture of two or more groups selected from oxyethylene group, oxypropylene group, and oxybutylene group, and when two or more types are used, it may be added in a block form or randomly. , In indicates the average number of moles added.

Y is a dibasic acid, such as oxalic acid, malonic acid.

Succinic acid, glutaric acid, adipic acid, pimelic acid, corkic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, isosuccinic acid, methylsuccinic acid, ethylmalonic acid, dimethylmalonic acid, malic acid, Tartronic acid, maleic acid, fumaric acid, oxalacetic acid, tartaric acid, mesooxalic acid, acetone dicarboxylic acid, citraconic acid, mesaconic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, homophthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid ,
Dihydrophthalic acid, 0-phenyleneacetic acid, m-phenylenediacetic acid, 5p-phenylenediacetic acid, 0-phenyleneacetic acid-β-propionic acid, naphthalene-2,3-dicarboxylic acid, naphthalene-1,2-dicarboxylic acid, naphthalene-
1,8-dicarboxylic acid, diphenic acid, aspartic acid,
Indicates a residue of a dibasic acid such as glutamic acid, α-ketoglutaric acid, α-oxyglutaric acid, etc.

In addition to the structures of formulas [I] to [■], Z is a partially substituted product thereof, such as in the case of formula [I]1 and in the case of formula [■].

In the case of formula [V], In the case of formula [VI], It includes structures such as.

When the crosslinking agent of general formula [I] having each of the above structures reacts specifically with the amino group of chitosan, it liberates N-hydroxyimide and reacts with the amino group of chitosan to form an addition product. Therefore, as shown in the example below, it acts as a crosslinking agent for the amino group of x1-san and performs a crosslinking reaction in an aqueous solution at room temperature.

Polymerize chitosan to form a gel.

In the above reaction, when X is an alcohol residue generated from a diol such as ethylene glycol or propylene glycol, n is 2, the crosslinking agent becomes difunctional, and a relatively soft gel is formed.

In addition, when X is an alcohol residue derived from a polyol such as pentaerythritol or sorbitol, n
is 4 or 6, the crosslinking agent is polyfunctional, and when a gel is made with these, a rigid gel with a high crosslinking density is formed.

In addition, when A is an oxyethylene group, the crosslinking agent has a greater affinity for crosslinking than when it is an oxypropylene group or an oxybutylene group. In the case of a copolymer of oxypropylene groups and oxybutylene groups, the degree of hydrophilicity varies depending on the ratio of each component, so the degree of hydrophilicity of crosslinked chitosan can be adjusted by this.

m can range from 1 to 500, but the smaller m is, the more
Since the crosslinking density per unit weight of the crosslinking agent increases, crosslinked chitosan tends to form a rigid gel, and the wood-philicity of the crosslinking agent decreases. When m exceeds 500, the crosslinking density per unit weight of the crosslinking agent becomes too low, and its action as a crosslinking agent becomes extremely small, making it unsuitable for practical use.

Note that the dibasic acid having Y as a residue is arbitrarily selected from the viewpoint of ease of esterification with an oxyalkylene adduct of alcohol and an acid imide.

In addition, as acid imides, phthalimide whose partial structure of Z is general formula [■] and its partially substituted product, general formula [V]
and its partially substituted product, maleimide, and the general formula [VI] and its partially substituted product, succinimide, are desirable because they are easy to produce industrially and are inexpensive.

The crosslinked chitosan of the present invention can be obtained by adding a crosslinking agent to a dilute aqueous chitosan acid solution and thoroughly mixing the mixture.

A dilute acid aqueous solution of chitosan is hydrochloric acid, acetic acid, sulfuric acid, etc. to adjust the pH.
1 to 10% by weight of chitosan in an aqueous solution adjusted to 4 to 5.
Add and stir thoroughly to dissolve.

The mixing ratio of Ki1 to San and the crosslinking agent is 100:1 to 50 by weight. The reaction is carried out at a temperature of about 20-30°C, and after mixing for about 5 minutes at 1100°C-200°C using a disper, the mixture is allowed to stand at 40-60°C for 2-3 hours.

[Effects of the Invention] The crosslinked chitosan obtained in the present invention is a new polymer compound, and has excellent heat resistance and flexibility, and is expected to be used in pharmaceutical related fields such as artificial skin.

[Example] Next, the present invention will be specifically explained with reference to Examples. %
indicates weight %.

Example 1 Chitosan P S H [Yaizu Suisan Co., Ltd. trade name, white powder, average molecular weight: 10000, elemental analysis value (theoretical value): C43.8% (45.0%) in 0.5% acetic acid aqueous solution , I
! 6, :l1% (6,8%), N 8.8'! ,(8,
5%) was added to prepare a 5% aqueous solution.

To this, a crosslinking agent represented by the formula [X], P-6000 [trade name of Nippon Oil & Fats Co., Ltd., white powder 1 molecular weight near 000, pH]
: 3,5. Moisture: 0.44%, elemental analysis value (theoretical value)
:c 53.1% (53.4%), 88.9% (8.5
%).

NO, 7% (0,8%)] wochitosan/crosslinking agent 31
0.1.310.2.310.4 and 310.8 were mixed at a weight ratio of 11000pp using a desper.
After stirring for 5 minutes, transfer to a polyethylene container (15 x 30
x1cm) and reacted at 40°C for 3 hours.
A film having a dry film thickness of 35 μm was obtained. This film was used as a test piece.

CI□-〇-machi
Nippon Oil & Fats Co., Ltd. product name, white powder, molecular weight: 5700,
pH: 3.8. Moisture: 0.41% 1 element analysis value (theoretical value): C52, parts (53,4%) 418.3% (8,5
%).

NO, 8% (0.8%) and chitosan/crosslinking agent are 31
They were mixed at a weight ratio of 0.1.310.2.310.4 and 310.8, respectively, and a film test piece was prepared in the same manner as in Example 1.

C112-0 Series Example 2 A 5% chitosan aqueous solution was prepared in the same manner as in Example 1. Example 3 A 5% chitosan aqueous solution was prepared in the same manner as in Example 1.
Cross-linking agent shown by the formula [Shopco], AM-102 [NOF (NOF)
Co., Ltd. product name, white powder, molecule ffi: 3400, PI4
: 3.6. Moisture: 0.46%, elemental analysis value (theoretical value)
:C53.6% (53.4%), 118.9% (8.5
%).

N008% (0.8%)] and chitosan/crosslinking agent is 310
, 1.310.2.310.4 and 370.8 weight ratios, respectively, and coated test pieces were prepared in the same manner as in Example 1.

Comparative Example 1 A 5% chitosan aqueous solution was prepared in the same manner as in Example 1,
Pour into a polyethylene container (15 x 30 x 1 cm),
Volatile components were evaporated at 40° C. and 600 to 760 mmHg for 3 hours to obtain a film with a dry film thickness of 35 μm. This film was used as a comparative test piece.

For each test piece obtained above, gel fraction, elongation at break,
Tensile strength and heat loss were measured.

The results are shown in Tables 1 and 2. Furthermore, an infrared absorption spectrum diagram of the crosslinked chitosan obtained in Example 1 is shown in FIG.

Test method〉 Gel fraction: Take 5 pieces of each test piece and add 1 piece of 0.5% acetic acid aqueous solution.
00ml was added and mixed using a homomixer at 20°C for 2 hours to dissolve. Thereafter, this solution was filtered through a filter paper, and the residue was dried at 40° C. for 3 hours, then the weight of the residue was measured, and the ratio of the weight of the residue to the weight of the test piece was expressed as %.

Tensile test: Cut each test piece into a size of 80 x 10 mm and use a tensile tester [Strograph W manufactured by Toyo Seiki Co., Ltd.]
The elongation at break and tensile strength were measured using

Note that the stretching was carried out indoors at a room temperature of 20'C, and the pulling speed was 5 mm/min.

Heating loss: Take 10o+g of each test piece,
at! using ePoint Pyrolyser [manufactured by 8 Water Analysis Industry Co., Ltd.]. I decided. The heating rate was 10°C/min, the temperature range was 25 to 600°C, and the loss on heating was expressed as X.

As is clear from Table 1, the chitosan of Comparative Example 1 dissolves in the dilute acid aqueous solution and has a gel fraction of 0%, whereas the crosslinked chitosan obtained in the example no longer dissolves in the dilute acid. ,
It showed a high gel fraction. Also, in terms of elongation at break,
Crosslinked chitosan showed higher values compared to chitosan.

As shown in Table 2, in terms of heating loss, especially 3
The difference between the two is obvious at around 00°C.

That is, chitosan showed a significant change in Wt at 200 to 300° C. that appeared to be due to thermal decomposition, but crosslinked chitosan was found to be less susceptible to heat.

From the above, crosslinked chitosan obtained by reacting chitosan with a crosslinking agent is a two-dimensional polymer compound that no longer dissolves in dilute acid aqueous solution, and is a flexible film.

Tsugu @ Yuzu 4, f in the drawing! Figure 1 shows the chitosan/P-600 obtained in Example 1.
0=310,4 (weight ratio) is an infrared absorption spectrum diagram of crosslinked chitosan.

Claims (1)

[Scope of Claims] 1) Crosslinked chitosan obtained by reacting chitosan with an N-hydroxyimide ester compound represented by the general formula [I]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...［I］ (However, in the formula, X is the residue of a compound with 2 to 6 carbon atoms and 2 to 6 hydroxyl groups, A is an oxyethylene group, One or more mixed groups selected from oxypropylene group and oxybutylene group, Y is dibasic acid residue, Z is (1) formula [II] ▲ Numerical formula, chemical formula, table, etc. ▼ and its Partially substituted products, (2) Formula [III] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and its partially substituted products, (3) Formula [IV] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and its partially substituted products, (4) Formula [V] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and its partially substituted products. (5) Formula [VI] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and its partially substituted products, (6) Formula [VII] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and partially substituted products thereof, and (7) Formula [VIII] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and a group selected from its partially substituted products, m is 1 ~500, n indicates 2 to 6.)