JPS5986640A - Chitin suspension and production thereof - Google Patents

Abstract

PURPOSE:To produce easily a finely divided chitin suspension which is stable only by mechanical operation without using any chemical agents, by treating a coarsely powdered chitin suspension with a high-pressure homogenizing apparatus. CONSTITUTION:A high-pressure homogenizing apparatus is used which is operated in such a manner that a suspension which is caused to flow into a valve device 1 in the direction of an arrow is passed through a small-diameter orifice 3 between a valve seat 2 and a valve 4 to apply pressure to the suspension and to rapidly accelerate it and is made to collide with a collision ring 5 to rapidly reduce the speed. Chitin obtd. from crab or shrimp, refined and crushed to small pieces (the longest being 1-2mm.) is dispersed in water (concn. being 10wt% or below). The suspension is introduced into the homogenizing apparatus and passed therethrough while applying a pressure of at least 200kg/cm<2>, pref. 350- 560kg/cm<2> to the suspension. By repeating this stage, a chitin suspension is produced in which the content of the stabilized suspension is at least 50% after 0.5wt% suspension having a water retention value of at least 200% is left to stand for one hr.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stable aqueous suspension of chitin and a method for producing the same.

Chitin exists in large amounts in nature, and like cellulose, it is attracting attention as a source of linic acid. That is, chitin is present as a structural polysaccharide in the cell walls of crustaceans such as shrimp, krill, and crabs, insects such as rhinoceros beetles, and fungi, and is widely and actively produced in nature. However, to date, it has hardly been used as a resource, and even though it is only subject to disposal, it is not a 51st opinion. Chitin can be used for paper,
Additives to textiles, additives to photographic products, pharmaceuticals, cosmetics, and anti-111ig agents have been proposed, but in order to do so, it is necessary to formulate them in a form that can be used effectively.

Chitin is a polysaccharide with a chemical structure consisting of β-1,4 bonds of N-acetyl-D-glucosamine, but it is extremely stable against chemicals, so it requires complicated treatments to dissolve it in solvents or derivatize it. However, it has not yet reached the stage where it can be used industrially, and requires the use of special chemicals.

However, chitin can be used as it is or in the form of fine particles or suspension. There are several proposals to make it into fine particles or suspension, but the manufacturing method is complicated, the action of the chemical is too strong, leading to molecular collapse, and the suspension is unstable and cannot be used for a short period of time. Most of them have the disadvantage of solid-liquid separation, and none have been put into practical use yet.

Chitin is even more difficult to mechanically crush than cellulose etc.)
Even if freeze-pulverization is performed, the particle size is limited to 200 μm. Some attempts have been made to dissolve chitin in concentrated sulfuric acid or concentrated hydrochloric acid and pour the solution into water to precipitate chitin in the form of fine particles, but these methods either result in molecular collapse (cleavage of glucosidic bonds, partial deacetylation) or partial deacetylation. Due to the sulfation of chitin, it is no longer a highly pure chitin (Japanese Patent Publication No. 51-6720, etc.).

So-called microcrystalline chitin obtained by treating chitin with acid (USP 3,847,897 (1974)
, USP 4,059,457 (1977), but these also have problems such as partial deacetylation when using hydrochloric acid, and a small amount of phosphorus binding when using phosphoric acid.

As a result of extensive research, the present inventors have discovered that a stable fine-particle chitin suspension can be prepared solely by mechanical action without using chemical agents, leading to the present invention.

The present invention will be explained in more detail below.

The manufacturing method of the present invention consists of the following two steps. That is, (1) a suspension of chitin is passed through a small diameter orifice, and the suspension is mixed with at least 200 ml of chitin. 7/c
A process in which a high velocity is applied with a pressure difference of 4, and then a shearing action is performed by rapidly decelerating this by collision (
2) A step of repeating the first step so that the chitin suspension becomes a stable suspension that does not undergo solid-liquid separation even when left standing.

Apparatus suitable for carrying out the present invention is widely used by dairy manufacturers and others.
This is a high-pressure homogenization device used for producing emulsions and dispersions. Homogenizers of this type and their operating mechanisms are well known, e.g.
Engineering 1a (5) 86-92 (
1974).

The outline of the homogenizing device will be explained with reference to the drawings. This type of device applies energy to a low viscosity suspension to force it to flow out of a narrow agitation chamber at high speed. The heart of the device is the valve and seat arrangement of the homogenizer, which is mounted on the discharge end of the high-pressure pump. FIG. 1 shows a typical valve device. The suspension is allowed to flow into the valve device 1 as indicated by the arrow. At this point of entry, the suspension is under high pressure but at low velocity. This liquid is applied to valve 4 and valve seat 2.
As it enters the small diameter orifice 3 formed in the narrow gap in the darkness, its velocity increases to 200ffi/
rapidly accelerated to seconds. The pressure drops between the inlet and outlet sides of the orifice 3.

As the suspension emerges from between the valve 4 and the valve seat 2, it hits the impingement ring 5 surrounding the orifice and its high velocity is reduced.

In carrying out the present invention, the raw material is purified from crabs, shrimps, etc. in its properly moistened state, or once dried and then ground into small pieces of about 1 to 2 mm in length at the longest part.

This is dispersed in water to make a suspension, but the amount of chitin dispersed is at most 10% in terms of weight percentage.
and is preferably in the range of about 1 to 5%.

This suspension was introduced into the homogenizer for at least 20 min.
Apply a pressure of 9/d to 0, preferably 350 to 560 kg/cU. This suspension is then passed through a homogenizer several times to obtain a stable chitin suspension. The temperature of the suspension increases as it passes through the homogenizer.

It is believed that the interplay of pressure drop and temperature increase during passage through the homogenizer is necessary to produce a stable chitin suspension according to the present invention.

The aqueous suspension of chitin obtained by the present invention has physical properties similar to those of the aqueous suspension of beaten bulb, and has high water retention and suspension stability in water. If the number of passes through a homogenizing device during production is reduced, a paper-like sheet can be obtained using a papermaking method, and if the number of passes through a homogenizer is increased, a film-like sheet can be obtained using a casting method.

This will be explained in more detail with reference to Examples below. 6- Definition, measurement method, etc. of the properties of chitin suspensions shown in Examples will be summarized.

(1) Stable amount: Dilute the gel-like 111J suspension of chitin with water to prepare a dispersion of 0, s wt %. 100ml of this! The stable amount is a value defined as 100-A, where A- is the amount of clear supernatant liquid that is produced after the sample is placed in a graduated cylinder and allowed to stand at room temperature for 1 hour.

(2) Water retention value;
Place it in a wire mesh basket with a mesh size of 0 and centrifugal effect of 1000.
Treat with centrifugal force for 10 minutes to dehydrate. Then, take out the sample and measure its weight (Wlg). Next, this sample is dried at 105° C. until it reaches a constant weight t(t), and its weight W2.!i' is measured.

The water retention value (~VRV) is calculated using the following formula.

2 Example 1 40 g of commercially available chitin powder (Kyowa Yushi Glφ) was dispersed in 2 parts of water to prepare a 2wtfA chitin suspension. This was transferred to a Gaulin homogenizer (15M-8TA) at room temperature (
(approximately 25°C) and passed five times at a pressure of 560 kg/cA. As the number of passes increases, the suspension becomes more viscous and gel-like.

At the end of five passes, the liquid temperature reached 51°C, and a stable gel-like chitin suspension was obtained. When the stable amount and water retention value of this were measured, values of ioo and 580% were obtained, respectively.

Examples 2 to 4 Experiments were conducted to understand the relationship between the number of passages through the homogenizer and the characteristics of the product. The same experiment as in Example 1 was conducted, except that the number of passes was changed to 10, 15, and 20 times.

The properties of the obtained gel-like chitin suspension were as shown in Table 1.

7- Calculated from the value of 445ec-' in Table 1 (25°C). The solid content concentration is 1 wt%.

Furthermore, all of these gel-like chitin suspensions exhibit ticuntropic properties.

Figure 2 shows the sliding speed of the gel suspension obtained in Example 4.
The shear stress relationship curve is shown.

Example 5 An experiment was conducted to examine the influence of the suspension temperature when passing through a homogenizer. In the same manner as in Example 1, a suspension of commercially available chitin (Kyowa Yushi e[) 40.9 and water 2e was prepared and heated to 80°C. This was charged into a homogenizer and passed through 560 at a pressure of 9/9-8-1 five times. As the number of passes increases, the suspension becomes more viscous and becomes gel-like. At the end of five passes, the liquid temperature was 85°C, and a stable gel-like chitin suspension was obtained. When we measured the stable amount and water retention value of this, we found that
Values of 100 and 760 chi were obtained, respectively. From this result, it was confirmed that by preheating the suspension slurry, fewer passes were required to obtain the same water retention value.

Comparative Example 1 An experiment was conducted to compare a stable chitin suspension according to the invention with a suspension obtained from microcrystalline chitin.

One slice of commercially available chitin (Kyowa Yushi) was dispersed in a 0.5% hydrochloric acid aqueous solution 70β, and this was placed in a glass-lined pressure cooker. Heat this at about 130℃ (1.5~2.OJ
c9/caG) for 1 hour, and after cooling, the hydrochloric acid was neutralized with an aqueous ammonia solution. Next, washing with water was repeated until chlorine ions were no longer detected, and after grinding with a Disc Refiner-10-, dry smoke was carried out with a spray dryer to obtain microcrystalline chitin in the form of fine particles. Using this microcrystalline chitin, a 0.5 wt water suspension was prepared based on the "crystalline cellulose" section of the Japanese Pharmacopoeia, and the stable amount was measured to be 6. In addition, a 25 wt % gel suspension was prepared based on the above pharmacopoeia, and the water retention value was measured and found to be 145.

Example 6 Chitin@seed liquid according to the present invention can be used as a paper strength enhancer.

The chitin gel suspension obtained in Practical Example 4 was added in an amount of 0.5, 1, 2.3 wt % of the paper pulp in terms of chitin solid content, and thoroughly mixed and dispersed in a mixer. This is JIS
The paper was made using a hand paper machine in accordance with P8209-1961. Table 2 shows the properties test results of the obtained sheet.

Table 2 (Note) Bleached kraft pulp was used for the papermaking valve.

The result may be that chitin r/d according to the present invention, ceramic liquid ('J
.

It can be seen that it has young fruits that are remarkable as paper strength enhancers.

Example 7 The chitin suspension obtained in Example 4 was flowed onto polyethylene sand and dried at room temperature. Smooth translucent thickness approx. 25μ
m sheets were obtained.

It can be written on with pencil, ink, or ink, and can be used as tracing paper to produce clear copies.

[Brief explanation of the drawing]

No. 11 is a schematic cross-sectional view of a homogenizing device applied to carry out the method of the present invention and an enlarged view of its part. 1° Valve device 2. Valve seat 3. Small diameter orifice 4, valve 5
．． Collision ring FIG. 2 is a diagram showing the relationship between the sliding speed and the sliding stress of the chitin suspension according to the present invention. Daicel Chemical Industry Co., Ltd. -13-

Claims (2)

[Claims] (1) Water retention value is 200% or more and 0.5% by weight
A chitin suspension having a stable amount of 50 or more after the suspension is left for 1 hour. (2) Passing a suspension of chitin powder through a small diameter orifice to give the suspension at least 200/C9/J
A step of applying a high velocity with a pressure difference of t, and then causing the collision to cause a rapid deceleration to cause a shearing action;
A method for producing a chitin suspension comprising the step of repeating the above steps so that the chitin suspension becomes a substantially stable suspension.