JP3309886B2 - Method for producing starch fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing starch fibers, and more particularly, to a novel and improved method for producing starch fibers capable of obtaining starch fibers having an arbitrary average fiber length depending on the application. It is about.

[0002]

2. Description of the Related Art Starch fibers made from starch in the form of pulp have been conventionally used, for example, as a substitute for all or part of wood pulp. And the retention of internal chemicals used in papermaking is improved. It is also used in mixture with wood pulp in the production of glassine paper utilizing the transparency of starch fibers.

[0003] As a method for producing such starch fibers, a starch suspension is heated or alkali-treated to form a colloidal dispersion of starch, which is converted into a filamentous flow in a coagulation bath comprising an aqueous solution of ammonium sulfate or the like. And a method of coagulating a starch colloidal dispersion obtained by boiling and dissolving a starch aqueous suspension by a jet cooking method in a coagulation bath (for example, US Pat. No. 4,139,699, Italy). Patent application 91A000610, Sho 60-354 80 No., etc.).

[0004]

The fiber length of the starch fiber obtained by the above-mentioned conventional production method is, for example, less than 1 mm in Italian Patent Application No. 91A000610.
In JP 60-354 80 No. is described as 0.1 to 3.0 mm. However, when starch fibers are used in the papermaking field, for example, if the fiber length is extremely short, the fibers fall out of the wire during papermaking and the intended purpose cannot be achieved. There is a disadvantage that the paper is fed as it is.

[0005] Further, in the case of using the transparency of starch fibers, it is conceivable that the transparency obtained by the difference in the fiber length of the starch fibers also changes.

[0006] As described above, if starch fibers having an arbitrary fiber length can be used according to the purpose, the intended purpose of use can be effectively achieved, and further, an effect which has not been considered until now can be expected.

Accordingly, an object of the present invention is to provide a method for producing a starch fiber in which the fiber length can be arbitrarily controlled as required.

[0008]

The inventors of the present invention have conducted intensive studies and found that there are some types of natural starch, some of which are spinnable, and some of which do not, which result in long and short starch fibers, respectively. That is, they have found that by using a raw material obtained by mixing both species in an appropriate ratio, a starch fiber having a specific fiber length distribution can be obtained in accordance with the mixing ratio, thereby completing the present invention.

[0009] Namely the present invention, the colloidal dispersion of starch Te method odor producing starch fibers by spinning, were mixed with starch without starch and spinnability with hauls yarn properties at a predetermined mixing ratio starch The mixture
A colloidal dispersion is prepared using
By spinning, a specific flatness according to the mixing ratio is obtained.
A method for producing starch fibers, characterized by obtaining starch fibers having a uniform fiber length distribution .

In the present invention, the term "starch having no spinnability" means a starch fiber having an average fiber length distribution of about 1 mm or less when starch fibers are prepared by the following method. Certain starch refers to one from which starch fibers having an average fiber length distribution of about 15 mm or more can be obtained.

A method for preparing starch fibers for examining the spinnability is as follows. First, a 10% by weight aqueous suspension of starch is prepared and heated and swelled to 95 ° C. to obtain a starch colloidal dispersion. . The dispersion is discharged at a constant temperature of 55 ° C. into the coagulation bath at a discharge pressure of 3 kg / cm ² from a nozzle having a diameter of 0.4 mm provided in the coagulation bath. A 40% by weight aqueous solution of ammonium sulfate is used as a coagulation liquid in the coagulation bath, and the coagulation bath is stirred so that the discharge direction of the starch dispersion and the flow direction of the coagulation liquid are at an angle of about 45 °.

The average fiber length distribution of starch fibers was measured by the following method. The starch fiber prepared as described above is taken out of the coagulation bath, spread on a preparation, dried and fixed, then enlarged by a projector, and the length of each fiber is measured using a map meter. Approximately 200 starch fibers are fixed per preparation, and 10 preparations are prepared in one test, and the average fiber length distribution is obtained by calculation from the results of performing three tests on one type of starch.

[0013] By actually preparing starch fibers from starch by the above-mentioned method, it is possible to distinguish between a spinnable starch type and a non-spinnable starch type. The following are examples of starch types found from the results of the present inventors.

Spinnable starch varieties: potato, cassava (tapioca), taro, sweet potato, potato, daijo, yautea, hariimo, yam, yam, guinea yam, indian kuzuimo, quilts verma and the like.

Non-spinnable starch species: corn,
Wheat, rice (rice), barley, rye, oat, sorghum, millet, millet, millet and the like.

In general, there is a tendency that starch obtained from plant stems and roots has spinnability, and starch obtained from grains does not have spinnability. It will need to be prepared and judged. Although the starches exemplified above are all natural starches, the starches that can be used in the present invention are not limited to natural ones, and even modified starches such as modified starches are classified according to the presence or absence of spinnability as described above. Anything that can be used can be used.

In practicing the present invention, first, starch particles obtained by mixing a spinnable starch and a non-spinnable starch at an arbitrary ratio are suspended in water to prepare an aqueous suspension. Then, it is heated and swelled to form a starch colloidal dispersion. If the starch concentration of the aqueous starch suspension is low, the cohesive force at the time of agglomeration at the time of spinning decreases, and if the starch concentration is high, the fluidity of the swollen starch colloidal dispersion is lost and spinning becomes impossible. The starch concentration varies depending on the type of starch and the like and cannot be unconditionally determined, but is generally preferably 5 to 20% by weight. The heating temperature may be any temperature at which the starch can be sufficiently swollen and gelatinized, and generally a temperature of 100 ° C. or less.

The colloidal starch dispersion which swells and exhibits a colloidal state is cooled and spun while maintaining a predetermined temperature. The temperature of the colloidal starch dispersion during spinning is 50 to 6
Preferably, it is maintained at 0 ° C. It is known that when the temperature of the dispersion changes, the viscosity changes, so that stable starch fibers cannot be obtained, and that when the temperature drops significantly, starch aging occurs.

Next, the starch colloid dispersion maintained at a predetermined temperature is placed in a closed container, and a constant pressure is applied thereto, and the mixture is discharged into a coagulation bath from an arbitrary number, diameter and shape of nozzle openings. It can be spun into starch fibers by wet spinning. Such a wet spinning method is a method conventionally used as a spinning method for a viscose fiber or the like, and therefore, an existing spinning apparatus can be used. The diameter (thickness) of the starch fiber can be adjusted by changing the diameter of the nozzle.

As the coagulating liquid in the coagulating bath, an aqueous solution of a salt which forms an electrolyte in water such as ammonium sulfate, sodium sulfate, magnesium sulfate, ammonium phosphate, sodium carbonate, ammonium chloride, etc. can be used, and ammonium sulfate is particularly preferred. If the concentration of the coagulation liquid is low, the coagulation effect cannot be sufficiently obtained, and generally, an aqueous salt solution having a concentration of about 30 to 40% by weight is preferable.

The coagulation liquid in the coagulation bath is constantly stirred to generate a flow in the coagulation liquid. The direction and speed of the coagulation liquid flow influence the fiber length and strength of the resulting starch fibers. That is, in order for the starch dispersion discharged into the coagulation liquid to have a stable thread-like flow, it is desirable that the discharge direction of the starch dispersion and the flow direction of the coagulation liquid coincide with each other. If they cannot be matched from the design, the discharge direction and the flow direction of the coagulating liquid are 9
When the angle is set to 0 ° or less, a thread-like flow can be formed in the starch dispersion. In addition, by making the flow rate of the coagulating liquid higher than the discharge rate of the starch dispersion liquid to stretch the starch filamentous material, the insolubilization of starch fibers in water and the strength of starch fibers can be improved. However, if the flow rate of the coagulating liquid is excessively high, the starch filaments may be torn in the coagulating bath, and a desired fiber length may not be obtained. For the above reasons,
The flow direction and flow rate of the coagulation liquid need to be determined by preliminary experiments so that the desired starch fibers can be obtained.

[0022]

The present invention will be further described below with reference to examples. A 10% by weight aqueous suspension of a starch mixture in which the mixing ratio of potato starch and corn starch was variously varied was prepared and heated and swelled to 95 ° C. to obtain a starch colloidal dispersion. 40% by weight of ammonium sulfate
A round nozzle having a diameter of 0.4 mm was placed in a coagulation bath comprising a coagulation solution of an aqueous solution, and the above-mentioned starch colloid dispersion was added to a coagulation bath.
The mixture was discharged from a nozzle into a coagulation bath at a discharge temperature of 3 kg / cm ² at a constant temperature of 5 ° C. to produce starch fibers. During the discharge, the coagulation bath was stirred so that the discharge direction of the starch dispersion and the flow direction of the coagulation liquid were at an angle of about 45 °.

Table 1 and FIG. 1 show the relationship between the mixing ratio of potato starch (potato) and corn starch (corn) and the average fiber length distribution of the obtained starch fibers.
In addition, a micrograph of the starch fiber obtained in each experiment is also shown.

[0024]

Table 1 Starch mixing ratio (% by weight) Average fiber length distribution Micrograph [potato / corn] (mm) (26 times magnification) 0/100 0.9 ± 0.18 Figure 2 30/70 3.3 ± 0 .80 50/50 4.9 ± 0.57 FIG. 4 70/30 9.7 ± 0.54 FIG. 5 100/0 18.2 ± 2.2 FIG.

[0025]

As can be seen from the above description, according to the present invention, the use of a raw starch in which the mixing ratio of a spinnable starch and a non-spinnable starch is changed allows an arbitrary average Starch fibers having a fiber length distribution can be easily produced. By using such a controlled starch fiber of fiber length depending on the application, it is possible to expect the expression of effects that could not be obtained when using a conventional starch fiber whose fiber length is not controlled, Use of starch fibers can be expanded.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the mixing ratio of potato starch (potato) and corn starch (corn) in the raw material starch and the average fiber length distribution of the obtained starch fibers.

FIG. 2 is a micrograph of a starch fiber obtained from a raw starch having a potato / corn mixing ratio of 0/100 (corn only).

FIG. 3 is a photomicrograph of a starch fiber obtained from a raw starch having a potato / corn mixture ratio of 30/70.

FIG. 4 is a photomicrograph of starch fibers obtained from a raw starch having a potato / corn mixing ratio of 50/50.

FIG. 5 is a photomicrograph of starch fibers obtained from a raw starch having a potato / corn mixing ratio of 70/30.

FIG. 6 is a micrograph of a starch fiber obtained from a raw starch having a potato / corn mixing ratio of 100/0 (potato only).

Claims (2)

(57) [Claims] 1. A colloidal dispersion of starch Te method odor producing starch fibers by spinning, hauls yarn resistant is starch and spinnable without starch and a predetermined mixed
Colloidal dispersion using starch mixture mixed in mixed ratio
Liquid, and spinning this colloidal dispersion.
Have a specific average fiber length distribution according to the mixing ratio.
A method for producing starch fiber, characterized in that starch fiber is obtained . 2. The method for producing starch fiber according to claim 1, wherein potato starch is used as the spinnable starch and corn starch is used as the non-spinnable starch.