JPS62240329A - Highly water-swellable cellulose and its production - Google Patents

Abstract

PURPOSE:To obtain the titled cellulose with specific 13C-NMR spectra, weak in intramolecular hydrogen bond, by forming or film casting of an alkaline dope prepared by homogeneously dissolving cellulose in an alkaline solution, neutralizing the resulting product in a salt-contg. acidic bath followed by rinsing. CONSTITUTION:An alkaline dope prepared by homogenously dissolving cellulose in an alkaline solution (pref. aq. NaOH solution) is formed or subjected to film casting, the resulting product being neutralized in a salt (e.g. Na2SO4)-contg. acidic bath (e.g. of sulfuric acid) followed by rinsing, thus obtaining the objective cellulose. This cellulose has the following characteristics: 1 fraction of high magnetic field side (>=85.5ppm) in the 4C carbon zone (90.0-78.8ppm) of 13C-NMR spectra 55-85%, 2 non-accessibility fraction determined by deuterium method pref. 45-20%, 3 Hb-value as a measure of intramolecular hydrogen bond (ratio of OH stretching vibration at 3,430cm<-1> to that at 3,360cm<-1>) <=1.2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cellulose molded article obtained from an alkali dope in which cellulose is uniformly dissolved, which has weak intramolecular hydrogen bonds and has a high water swelling 1.

[Conventional technology]

As is well known, cellulose, in the form of recycled T&I fibers, cellophane, etc., is a raw material for molded products with good dimensional stability and sufficient a-contract strength. However, in the case of regenerated cellulose fibers and regenerated films, more advanced functions, particularly high water swelling properties, are sometimes required, and the emergence of such cellulose is desired. However, cellulose with such advanced functions, particularly high water swelling properties, has not yet appeared.

[Problem that the invention seeks to solve]

In view of this situation, an object of the present invention is to provide a cellulose molded article that has essentially excellent water swelling properties and a method for producing the same.

[Means for solving problems]

As a result of intensive studies in this direction, the present inventors discovered that a specific cellulose can form an alkaline dope stably and uniformly, as disclosed in Japanese Patent Application No. 60-42438, and that the dope can be directly applied to the alkaline dope. They found that by neutralizing with an acid, a molded article with significantly lower intramolecular hydrogen bonds and excellent water swelling properties could be obtained, and the present invention was defeated.

That is, the cellulose molded article of the present invention has 13
In the C-NMR spectrum, the 04 carbon peak area (90
, O ~ 78.8 ppm), the fraction of the high magnetic field side (sharp peak component, higher magnetic field side than the circuit 85.5 ppm) is 55 to 85%. do. When the fraction is 85% or more, there is a drawback that the orientation of the molded product when wet is slightly deteriorated. Also 55
% or less cannot be obtained by the production method described below.

The cellulose molded products according to the present invention include powders, fibers, and films formed by casting methods.

To understand the structure of the film, 13C-NM
The deuterium IR method is usually used rather than the R method. Therefore, regarding the film according to the present invention, the above-mentioned 13C-NM
The structure defined by the R method is.

According to the findings of the present inventors, when the film is air-dried, the inaccessible content (fraction of the hydroxyl group that is not deuterated) as defined by the deuterated IR method is 45 to 20%. The IR absorption region based on the hydroxyl group during equilibrium deuteration reached by the method is < 343 based on the intramolecular hydrogen bond.
It is equivalent to a structure in which the ratio (Hb) of the optical density of the peak at 0 cm to the optical density of the peak at 3360 am is 1.2 times or less.

If the inaccessible content is less than 20%, the orientation during wetting may be poor, and if the inaccessible content is more than 45%, it cannot be obtained by the method of the present invention. The low intramolecular hydrogen bonding of the inaccessible part is a measure of high disorder and loose structure, which ensures high water retention, especially when wet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the present invention in detail, the 13C-NMR measurement method, the above-mentioned fraction evaluation method, the deuterated IR method, and the inaccessible fraction evaluation method will be explained with reference to the accompanying drawings.

13C-NMR method Using a pulse-Fourier transform type NMR spectrometer, solid-state high resolution fa
Measure the 3C-NMR spectrum. The sample is packed in a Teflon sample tube, the contact time is around 2 milliseconds, and the sample rotation speed is 3000 Hz or less. Samples are measured in air-dried soft parts or in wet conditions. The chemical shift of each peak was determined by setting the methyl peak of adamantene measured under the same conditions as above at 29.5 pp.

The measurement temperature was between room temperature and 60°C. The pulse integration was 500 times or less. Figure 1 shows 13C-N in the 04 carbon beak region of a typical molded product obtained by the present invention.
An MR spectrum is shown. The fraction on the low magnetic field side specified above is the shaded part in the figure, and can usually be found from the integral curve of the spectrum.0 Line segment a / b x in the figure
It is 100 (%).

Figure 2 shows an overview of the equipment used for measurements using the deuterium fR method. A cellulose film adjusted to a thickness of 10 to 30 μm is set in a deuteration cell (6).

The cell (6) is set at 70° C. to remove moisture and prevent absorption of heavy water. After leaving to stand for 10 minutes to remove excess water, the fR spectrum of the blank (mixed film before deuteration) is measured. Next, cylinder (1)
Send dry Nt gas at 25°C obtained through the drying silica gel (2) at a flow rate of 10100O/+ll1n.
((3) is a flow meter), put heavy water (20cc) set at 25℃ into a heavy water bubbling container, bubble it with N2 gas, introduce heavy water into the deuteration cell, ) Deuterate the above sample. Under this condition 1
Deuterate for 20 minutes and measure the IR spectrum with an IR spectrometer. First, as shown in Figure 3, 360
Draw a baseline touching the spectra of 01Ml-' and 3000(J-', and
The transmittance at the intersection of the perpendicular line corresponding to cm-' and the baseline was adopted as the intensity Y of the incident light at each wave number. Also, the intensity I of transmitted light at 3430 cta-' and 3360 cm''
As, the transmittance at the intersection of the perpendicular line of each wave number and the spectrum was used. Calculate the optical density from the obtained 1 and I,
(by taking the ratio) rb was determined.

Also, the inaccessible fraction is J, MANN, H, J.

Trans, Fara by 1'1ARRINAN etc.
Day Soc, 52+492 (1956).

In order to produce highly water-swellable cellulose molded articles according to the present invention, cellulose is dissolved substantially uniformly to form an alkaline dope, the alkaline dope is molded or cast, and then the alkaline dope is molded or cast in an acidic bath containing salt. A manufacturing method characterized by neutralization and subsequent washing with water may be used. Note that after washing with water, drying may be performed if necessary.

Next, the cellulose molded article according to the present invention will be explained in more detail according to the above-mentioned manufacturing procedure.

The raw material cellulose used in the present invention includes natural cellulose such as wood pulp, cotton, hemp, etc., those obtained by adjusting the degree of polymerization by acid hydrolysis, mechanically pulverized or blasted, or high-temperature cellulose. In addition, so-called regenerated cellulose, that is, cellulose that is regenerated by being dissolved in some solvent and then neutralized and regenerated or coagulated in a non-solvent, or by evaporation and coagulation of easily volatile solvent components, etc. can be mentioned.

Specific examples of the solvent used to obtain the molded article of the present invention include aqueous solutions of hydroxides of alkali metals such as sodium and lithium. In particular, these alkali metal hydroxides are preferable from the viewpoint of safety when the final molded product is used in the pharmaceutical or food fields.

In producing the dope used in the present invention, for example, cellulose is added to an aqueous solution of an alkali metal hydroxide for 10
℃ or below, in which case the alkali metal hydroxide is
Finally, an aqueous solution of about 2°5N is used to dissolve cellulose. In other words, it is also possible to change the alkali concentration in stages for dissolution. If the cellulose content is present in the dope thus obtained in a proportion of 3% by weight or more, moldability by a wet method is guaranteed. The upper limit of the cellulose concentration is not particularly limited, and can be increased depending on the degree of polymerization, crystallinity, intramolecular hydrogen bonding, etc. of cellulose. For example, in the case of cellulose having a degree of polymerization of 170, the concentration of cellulose in the dope can be increased to over 20%.

The dope of the present invention may optionally include a third substance, for example,
It is also possible to add diols, polyols, oils and fats, seasonings, pigments, fragrances, proteins, polysaccharides, and the like.

An acidic solution containing various salts is used as a coagulation bath in this production method. As the acid, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as acetic acid and formic acid are used. As the salt, alkali metal salts such as nitric acid, sulfuric acid, and acetic acid, alkaline earth metal salts, salts of amphoteric metals, etc. are used, and the temperature in the coagulation bath is up to 5 weight LA saturation concentration. The temperature of the coagulation bath is above the freezing point of the bath composition used and below 80°C. At temperatures above 80°C, thermal decomposition of the molded article occurs. Obtain cellulose molded products with high orientation at low temperatures. In order to make the molded product fibrous or film-like and more highly oriented, it is stretched in a coagulation bath,
It is also possible to stretch with a hot roller or the like before and after washing with water.

In some cases, the Mk final molded product may be washed with water, then shredded as it is, and put into the process of manufacturing end-use products. The moisture content of the cellulose molded product obtained by the present invention immediately after spinning is that of the dry type! 100-12 for 100 copies
You can change the one containing 00 parts.

As mentioned above, the feature of the cellulose molded product of the present invention is that it has a high water swelling property that cannot be achieved by conventional methods for producing regenerated cellulose molded products. This is because conventional regenerated cellulose is once dissolved in a solution as a cellulose derivative, so the operation of regenerating it is essentially essential, whereas in the dope used in the present invention, the operation of regenerating it is essentially essential. This seems to be closely related to the fact that since cellulose is dissolved in its original state, it is essentially only necessary to neutralize it when obtaining a cellulose molded article from this dope.

〔Example〕

The present invention will be explained below with reference to examples, but it is clear that the present invention is not limited to these examples.

11L Cellulose with a degree of polymerization of 310 obtained by blasting a softwood bulb (degree of polymerization 1.100') was cooled to 4°C 9,1
A uniform dope obtained by dissolving the dope in a caustic soda aqueous solution of 7 wt.% to a concentration of 7 wt.% was passed through an extruder equipped with a nozzle with 50 holes of 0.125 mφ.
It was discharged into a 10 wt 1% aqueous sulfuric acid solution (20° C.) containing 0 wt. After vacuum drying this cellulose fiber at 40°C for 24 hours,
-90.0~ of cellulose based on C-NMR measurement method
Of the total integrated intensity of the C4 carbon region appearing at 78.8 ppm, the fraction existing on the asppm higher magnetic field side was calculated and found to be 60%.

Approximately 5 g of this fiber was dried at 50° C. to a constant weight, and then immersed in water at 30° C. for 60 minutes.

Immediately after soaking, the sample was sandwiched between filter papers, the moisture on the surface was wiped, and the weight was measured to determine the swelling value.

was calculated and used as a guideline for swollen coal.

In the case of this fiber, the α value was 5.0.

"Instead of the coagulation bath in Example 1, Kasaji Soda was discharged into an aqueous solution of caustic soda at 20°C and 0.1 in. to coagulate it into threads, and then
It was neutralized by passing it into 0% sulfuric acid, washed with water and dried to obtain cellulose fibers.

The NMR high field fraction of this fiber is 2.5%, and the α value is 0.
It was 2. ” Ex JIJL 2i Polymerization degree 49 obtained by blasting the same valve as in Example 1.
A uniform dope was obtained by dissolving cellulose of No. 0 in a 9.1 wt.% aqueous solution of caustic soda at 0.degree. C. to a concentration of 3 vat.%. This dope is cast onto a glass plate,
After smoothing it to a thickness of about 500μ with a doctor knife, it was heated at 20°C and 10wt containing saturated Na and SO.

% sulfuric acid aqueous solution for neutralization and solidification to form a film.

After thorough washing under running water, a transparent film was obtained.

This film was dried at 50° C. until it had a constant weight, and then immersed in water at 30° C., and the α value was measured in the same manner as in Example 1 and found to be 4.8.

In the same manner, a thin film for infrared absorption spectroscopy with a thickness of approximately 10 μm was prepared, and the deuterated infrared absorption was measured.

The inaccessible content and intramolecular hydrogen bonding parameter Hb were 35% and 0.97, respectively.

Cellulose with a degree of polymerization of 420 obtained by processing a "Ji 11 Juji" engineered softwood valve in a screw extruder set at 110°C is dissolved to a concentration of 5% in an 8-t0% caustic soda aqueous solution cooled to 0°C. A uniform dope was obtained.

This dope was cast onto a glass plate and leveled with a doctor knife to a uniform thickness of about 500μ, and then 20wt.

The glass plate was immersed together with the glass plate in an aqueous solution containing 10% aluminum sulfate and 10wt% sulfuric acid to form a coagulated film of cellulose. The wet film peeled off from the glass plate was washed under running water for 2 hours or more and then air-dried to obtain a transparent film.

The inaccessible fraction and intramolecular hydrogen bonding parameter Hb of this film were measured and calculated by deuterated infrared absorption method according to the measurement method described above.
It was 8% and 0.89.

Also, cut this film into small pieces to obtain 13C-NMI? According to the method, 90.0 to 78.8 ppm of cellulose is produced, and 85 ppm of the total intensity of the C4 carbon region appears.

The fraction existing on the higher magnetic field side was measured and found to be 78%.

The α value was 6.8, indicating high swelling property.

Instead of the coagulation bath in Examples 2 and 3, the TJ-bums cast on a glass plate were first immersed in water at 30°C for 10 minutes to coagulate, and then Neutralized by transferring to a 10% sulfuric acid bath. When the film thus formed was washed with water and dried, 13C-NMR measurement, deuterated infrared measurement, and α value were measured, the results shown in Table 1 were obtained.

(Table 1)

[Brief explanation of drawings]

Figure 1 shows 13CN in the C1 to Ch carbon beak region of a typical cellulose molded product obtained by the method of the present invention.
This is an MR spectrum. FIG. 2 shows a schematic diagram of a deuterated infrared device for evaluating the inaccessible fraction (X) and the intramolecular hydrogen bonding parameter (Hb). 1 is an air supply pump 2 is a drying silica gel, 3 is a flow meter, 4 is a DzO bubbling container, 5
is a sample stage, 6 is a deuteration cell, and 7 is an infrared main body. FIG. 3 is an infrared absorption spectrum of deuterated fossils in the OH group and OD group regions.

Claims (1)

[Claims] 1. In the 13C-NMR spectrum, of the total intensity of the C4 carbon region appearing at 90.0 to 78.8 ppm of cellulose, the fraction existing on the higher magnetic field side than 85 ppm is 55 to 85%. A cellulose molded product characterized by: 2. The cellulose molded product is a film obtained by a casting method, and the inaccessible fraction defined by the deuteration method of the air-dried product is 45 to 20%, and the degree of intramolecular hydrogen bonding is The parameter Hb (3430c
The cellulose molded article according to claim 1, wherein the ratio of OH stretching vibrations of m^-^1 and 3360 cm^-^1 is 1.2 or less. 3. Cellulose molding, which is characterized by dissolving cellulose substantially uniformly to make an alkaline dope, molding or casting the alkaline dope, then neutralizing it in an acidic bath containing salt, and then washing with water. method of manufacturing the product. 4. The method for producing a cellulose molded article according to claim 3, wherein the washing treatment includes washing with water and drying.