JPH04194063A - Fine silk fiber material and its production - Google Patents

Abstract

PURPOSE:To obtain the subject fiber having excellent paper-making property, heat-insulation and printability and useful for paper-strengthening material, etc., by dispersing silk fiber in water, etc., passing the dispersion through a narrow orifice, letting the dispersion impinge against a vessel wall at a high speed to apply strong shearing force to the silk fiber by the quick deceleration and repeating the above procedures. CONSTITUTION:Silk fibers are dispersed in water or in an organic solvent which does not dissolve the silk fiber. The dispersion is passed through a narrow orifice at a pressure difference of >=200kg/cm<2>G and let impinge against a vessel wall at a high speed to effect the quick deceleration and the application of strong shearing force to the silk fiber. The above procedures are repeated to obtain the objective fine silk fiber material containing silk fibers, having nearly uniform diameter [a diameter of 0.01-1.0mum (measured in dry state) and an average diameter of about 0.1mum] and a length/diameter ratio of >=100 and distributed at random as a whole in non-bonded state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a fine silk fiber material, a fine silk fiber aggregate, and a method for producing the same.

[Prior art and its problems] Silk has been prized as the most valuable fiber since ancient times due to its unique luster, drapability, and texture. When spinning silk, a large amount of waste cotton, raw silk waste, etc. are generated, but as the price of raw silk has soared, it has become important to make effective use of these leftover silk threads.

Traditionally, fibers widely used industrially have a fiber diameter of about 3 to 20 mm, but in recent years, fiber diameters of 0.1
．． Fine fibers of about 1111 are attracting attention. 0.1
An aggregate of fibers having a fiber diameter of approximately tnn is useful in many respects because of its fine fiber diameter.

For example, it can be used as a filter material because it captures particles that cannot normally be captured, it can be used as a heat insulating material because it contains a large amount of air, and it can be used as a material for paper and paper strength because it has good printability. It can be expected to be used in many fields.

However, the fiber diameter of silk is usually 10J! m, and it was impossible to process it to 1- or less.

[Means to solve the problem]

The present inventors conducted extensive research to solve the above-mentioned problems, and as a result, completed the present invention.

That is, in the present invention, the diameter when measured in a dry state is 0.
It ranges from 0.01 m to 1.0 tm, with an average of 0.01 m to 1.0 tm.
II! Silk fibers of approximately uniform thickness with a length of approximately 100 times the diameter and a length of 100 times or more are present in a disorderly direction as a whole without being bundled.Does not dissolve water or silk fibers. In order to obtain a fine silk fiber dispersed aggregate made of the above-mentioned silk fiber material that does not cause re-agglomeration of the fine fibers in an organic solvent and a fiber diameter of about 0.1μ, the silk fibers are mixed with water,
Alternatively, an operation in which the silk fibers are dispersed in an organic solvent that does not dissolve them, passed through a small-diameter orifice with a pressure difference of at least 200 kg/cnlG, and caused to collide with the vessel wall at high speed to rapidly decelerate, thereby applying a strong shearing force to the silk fibers. The present invention provides a method for producing the above-mentioned fine silk fiber material, which is characterized in that the steps are repeated.

It should be noted that the expression "prevented reaggregation" here means that reaggregation does not occur. More specifically, the suspension of silk fibers is sufficiently stable even without treatment to prevent re-agglomeration, and becomes a suspension that does not re-agglomerate even if left standing.

In the present invention, silk fibers are micronized in the form of an aqueous dispersion, or in a dispersed state in an organic solvent that does not dissolve the silk fibers or in a mixture of the solvent and water. Examples of organic solvents that do not dissolve silk fibers include isopropyl alcohol and glycerin.

Further, in the present invention, a high-pressure homogenizer, a disc refiner, a Jordan, a beater, etc. are used to refine the fibers, and a high-pressure homogenizer is a particularly effective means. Examples of high-pressure homogenizers include Manto
Examples include those commercially available as n-Gaulin (trademark) homogenizers. This equipment is originally used to produce a homogeneous liquid emulsion, and includes a high-pressure pump, a valve device that discharges the liquid to be treated at high pressure from the high-pressure pump, a valve seat device that collides with the discharged liquid, and a high-pressure pump for the treatment liquid. Equipped with a circulation flow path to the suction side. Devices of this type and their operation are described in the known literature, for example in Chemical Engineering
g), 13(5), 86-92.1974.

Although high pressure homogenizer processing is essentially continuous, charging of processing liquids can be carried out in batches, ie, as a semi-continuous operation. The processing pressure and the number of processing times can be easily determined by comparing the properties of the obtained processing liquid with those desired. As the processing pressure increases, the same level of refinement effect can be expected even if the number of processing steps is reduced.

When treating silk fibers with this high-pressure homogenizer, prepare a silk fiber slurry (medium is water or an organic solvent that does not dissolve silk fibers) with a concentration of 0.5 to 10% by weight, preferably 1 to 5% by weight. At least 200 kg/ctl when passing the slurry through the small diameter orifice! G
A high velocity is applied with a pressure difference of , and then the velocity is rapidly decelerated by colliding with the wall near the orifice outlet, thereby shearing and cutting the silk fibers. By repeating this process until the silk fibers are microfibrillated and become a substantially stable suspension, a silk fiber material having a fine fiber diameter, which is the object of the present invention, can be obtained.

The stability of the suspension is evaluated by physical properties such as stable amount, water retention value, viscosity, and Schopper freeness. In the present invention, the stable amount, water retention value, viscosity, and Schopper freeness of the silk fiber suspension are measured by the methods shown below.

l) A stable amount of a gel suspension of silk fibers is diluted with water to prepare a 0.5% by weight dispersion. This was transferred to a 100 d measuring cylinder, and when the amount of transparent supernatant liquid produced after being left at room temperature for 1 hour was defined as Ad, the value defined by 100-A was defined as the stable amount. The stable amount is an index representing the difficulty of separation of a dispersed suspension, and the stable amount of a dispersion that does not separate at all is 100.

2) Water retention value A water suspension sample of silk fiber was placed in a 200 mesh filter cloth.
This is treated with a centrifugal force of 1300 centrifugal force for 20 minutes to remove liquid. Thereafter, the sample is taken out and its weight (01+g) is measured. Next, this sample is dried at 105°C until it has a constant weight, and its weight (Wz g ) is measured. The water retention value (W, R, V) is calculated using the following formula.

z Water retention value is an index representing water retention capacity, and the larger the value, the greater the water retention capacity.

3) Adjust the temperature of a suspension sample with a solid content concentration of 2% by weight to 25°C, and measure the viscosity using a B-type viscometer (manufactured by Tokyo Keiki), model BL, with a rotor Nα of 4.60 rotations. .

4) Chotsuparokibarji Sl? ) Conducted in accordance with JIS P8121-1976 R-valve ice charcoal test method.

In carrying out the present invention, silk fibers are soaked in a sodium carbonate aqueous solution (0.5%) heated to about 95°C to remove sericin, washed with water, dried, and pulverized to a fiber length of 0.5 mm or less. This is used as a raw material and dispersed in water or a suitable organic solvent that does not dissolve silk fibers to form a suspension. The concentration of the suspension is preferably in the range of 1 to 5% by weight.

This suspension is introduced into the above-mentioned high-pressure homogenizer, etc., and the
Apply a pressure of 0 kg/dG and pass through a high-pressure homogenizer. During this time, a shearing force is applied to the silk fibers, but the effect is mainly obtained as a tearing and peeling force in the direction parallel to the fiber axis, and the fibers gradually become microfibrillated and are defined by the above physical property values. The stability of the suspension as a suspension is increased.

〔Effect of the invention〕

According to the production method of the present invention, completely new fine silk fiber materials and fine silk fiber aggregates which are beyond the conventional common sense and which cannot be achieved using ordinary spinning techniques for obtaining thin fibers are provided.

The fine silk fiber aggregate obtained by the present invention has paper-making properties by itself, so it can be used as a filtering material, contains a large amount of air in the page air, so it can be used as a heat-insulating material, and has good printability, so it can be used as a paper. It can be expected to be used in many fields, such as for strength enhancement and as a material.

〔Example〕

The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Silk fibers from which sericin has been removed in advance are pre-pulverized using a centrifugal pulverizer (Nippon Seiki Seisakusho new product, Type 2M1). The wire mesh is 0.
A hole diameter of 25 m is used.

40 g of crushed silk fibers are dispersed in 1960 g of water to prepare a silk fiber dispersion having a solid content concentration of 2% by weight.

This was processed using a high-pressure homogenizer (Gaulin 15M-8
7A) at room temperature (approximately 25°C) and pressure 500kg.
/ciaG.

The treatment was carried out 100 times to obtain a silk fiber stabilized suspension. The physical properties of the obtained suspension were as follows: stable amount 100, water retention value 570%, viscosity 1040 cps, Schopper wood bark 9.
It was 4°SR.

The aqueous suspension obtained above was formed into a film by a casting method. Table 1 shows the physical properties of the obtained film. In addition, an electron micrograph of the same film is shown in Figure 1. In Figure 1, the average fiber diameter of the fibers that make up the film is approximately 0.1
− is.

Table-1 (Basic weight 60g/box) Measurement conditions: Rheometer (manufactured by Fudo Kogyo) Film Convergence; 10 Kakus Film length: 50m+ Tensile strength: 60m/win

[Brief explanation of the drawing]

FIG. 1 is an electron micrograph showing the shape of the fibers constituting the film obtained in Example 1. Applicant's agent Kaoru Furuya (3 others) Figure 1

Claims (1)

[Claims] 1. The diameter when measured in a dry state is from 0.01 μm to 1
．． Fine silk fibers that are in the range of 0 μm, average about 0.1 μm, and have a length of more than 100 times the diameter and have an almost uniform thickness that are not tied together but are arranged in a disorderly direction. material. 2. A fine silk fiber dispersed aggregate made of the silk fiber material according to claim 1, in which the fine fibers do not cause re-agglomeration in water or an organic solvent that does not dissolve silk fibers. 3 Disperse silk fibers in water or an organic solvent that does not dissolve silk fibers, pass through a small diameter orifice with a pressure difference of at least 200 kg/cm^2G, and collide with the vessel wall at high speed to rapidly decelerate the silk fibers. Claim 1 characterized in that the operation of applying strong shearing force to the fibers is repeated.
A method for manufacturing the fine silk fiber material described.