JPS6410521B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel cellulose derivative obtained by reacting methylolated cellulose with methylene diacetate or ethylene diacetate. Traditionally, the industrial method for producing molded products such as cellulose fibers and films involves dissolving cellulose in a cupric ammonia solution or xanthating it to form a solution, which is then coagulated and regenerated using an acid. It is carried out by. However, these industrial methods include many points that require improvement, such as large amounts of water consumption, the need to recover heavy metals, and high energy consumption. In recent years, in order to eliminate such drawbacks, a method has been proposed in which cellulose is dissolved in a new organic solvent and the resulting dope is directly spun and shaped, with the aim of closing the process. In addition to N-methylmorpholine N-oxide, which has attracted attention in recent years, dimethyl sulfoxide (hereinafter abbreviated as DMSO)/paraformaldehyde (hereinafter abbreviated as DMSO)
In the case of PFA (abbreviated as PFA) system, it is necessary to use two or more solvents in combination in actual application, which makes the method of recovering and reusing the solvent complicated, etc. It has been found that there is a fatal drawback in solvent recovery. In addition to these drawbacks, especially when using the DMSO/PFA system, there are
It is easy to cause the problem of thermal decomposition of DMSO. On the other hand, cellulose derivatives form liquid crystals in combination with specific solvents, and the molded products obtained from them are
Significant improvements in mechanical properties are expected. As a result of comprehensively examining the shortcomings of the prior art and new possibilities as described above, the present inventors have developed a new method that is soluble in a single solvent and that provides optical anisotropy when combined with a specific solvent. The present invention was achieved by discovering a cellulose derivative. That is, an object of the present invention is to provide a novel cellulose derivative which is easy to recover because it is soluble in a single solvent and which provides a dope with excellent moldability. The novel cellulose derivative according to the present invention comprises cellulose in the form of methylolated cellulose.
Dissolve in DMSO/PFA mixed solvent, then methylene diacetate (hereinafter abbreviated as MDA)
Or obtained by reacting with ethylene diacetate (hereinafter abbreviated as EDA), the number average number of pyranose rings in one polymer chain is 100 or more, and a methylenedioxy chain is present in the pyranose ring. The terminus is converted into the amount of bound acetic acid.
It is characterized by being substituted with acetyl groups at a ratio of 8.4 to 42% and having ultraviolet absorption in the range of 260 nm to 280 nm in a solution state. Up to now, several attempts have been made to dissolve cellulose in a DMSO/PFA mixed solvent and react with a reactant to obtain new derivatives. Hydroxyethylation of cellulose is one example. In addition, acetic acid,
Attempts to obtain new substances using acetic anhydride and acetic chloride were also made by R.B. Seymour (Journal).
of Polymer Science, 11 , (1978)). According to their point, among the reagents that can generally acetylate cellulose in a heterogeneous system, only acetic anhydride reacts with cellulose dissolved in a DMSO/PFA mixed solvent, and the resulting derivative is characterized by an ultraviolet wavelength around 340 nm. It is said to indicate absorption. Furthermore, they found that the presence of DMSO and PFA had a unique effect on each reactant for cellulose, and that the reactions between various reactants and cellulose, which were previously known to be heterogeneous, were It has also been suggested that it gives derivatives that could not be predicted. The present inventors also conducted repeated studies on the reaction between cellulose dissolved in a DMSO/PFA mixed solvent and an acetylating agent, and found that, contrary to the suggestions of R.B. Seymour et al., MDA or EDA was used as a reactant to react with cellulose. As a result, they surprisingly succeeded in synthesizing a new cellulose derivative that has ultraviolet absorption in the wavelength range of 260 nm to 280 nm in a solution state. The cellulose raw material used in the present invention may be natural cellulose such as cotton or wood (which may contain impurities such as lignin), or may be regenerated cellulose. Natural cellulose containing impurities such as lignin can be easily separated when dissolved in a DMSO/PFA mixed solvent because the impurities are insoluble. The degree of polymerization of the raw material (in this specification,
"Degree of polymerization" refers to the number average number of pyranose rings in one polymer chain. ) can be adjusted according to the purpose,
Usually, it is sufficient to have at least 100. Also,
The degree of polymerization is determined to improve the mechanical properties of the product.
You can also use more than 1000. When cellulose is dissolved in a DMSO/PFA mixed solvent, the concentration of cellulose in the solution is preferably 2 to 10% by weight, although it depends on its degree of polymerization. A sufficient amount of paraformaldehyde to be added is 3 to 5 moles per glucose residue of cellulose to be dissolved. The melting temperature is preferably 70°C to 90°C.
Extreme heating should be avoided as it causes decomposition of DMSO, which is a fatal drawback in industrialization. In some cases, it may be advantageous to remove excess paraformaldehyde from the cellulose solution once dissolved in subsequent reaction steps or solvent recovery steps. The amounts of MDA and EDA used as reactants can be appropriately selected depending on the properties of the final product to be obtained, especially the degree of substitution. For example, when you want to obtain a derivative that is soluble in polar solvents such as water, dimethylformamide, dimethylacetamide (hereinafter abbreviated as DMAC), and formamide (hereinafter abbreviated as FA) when the amount of bound acetic acid is 8.4 to 30%. requires 3 to 40 moles of reactant per glucose residue of cellulose. If it is desired to obtain a product with a higher amount of bound acetic acid, 40 moles or more of the reactant may be added. In general, both MDA and EDA serve as non-solvents for cellulose dissolved in a DMSO/PFA mixed solvent, so
Excessive use causes cellulose precipitation, which is not preferable. For example, the amount of MDA acceptable for a 3% by weight cellulose solution is
Up to twice the volume of DMSO. Incidentally, in this case, the amount of MDA is approximately 90 moles relative to cellulose. In this case, even if other reaction conditions are varied, the maximum amount of acetic acid bound in the resulting derivative is around 42%. On the other hand, in the reaction with MDA or EDA, the selection of catalyst is important, and sodium acetate is the most suitable catalyst. Other catalysts, such as pyridine,
When aluminum chloride, boron trifluoride ether complex, etc. are used, or when no catalyst is used, no reaction occurs or there is almost no effect of promoting the reaction. The amount of the sodium acetate catalyst to be added can be appropriately selected from several ppm to several thousand ppm. The important point here is that due to differences in the amount of catalyst, the solubility range of the resulting product in the same solvent varies depending on the amount of bound acetic acid. For example, when comparing the solubility range in water, the amount of sodium acetate used is
When the amount is 100 ppm, the lower limit of the amount of bound acetic acid that shows water solubility is 8.4%, whereas when the amount of sodium acetate used is 250 ppm, the lower limit of the amount of bound acetic acid that shows water solubility is 18%. The reason for this is not clear, but it is thought that one factor is that sodium acetate changes the reactivity of formaldehyde to cellulose. However, in any case, the aqueous solution of the product obtained exhibits ultraviolet absorption around 264 nm, and is clearly different from the material obtained by R.B. Seymour et al. The cellulose derivative obtained in the present invention has a methylenedioxy chain in the pyranose ring, and an acetyl group is substituted at the end of the methylene dioxy chain. Note that the reaction temperature is preferably 90 to 100°C. Since the degree of substitution of the cellulose derivative of the present invention cannot be uniquely determined, the amount of bound acetic acid is used as a substitute. The amount of bound acetic acid is the weight % of the amount of acetic acid (liberated as sodium acetate) liberated when a given weight of the product is treated with caustic soda relative to the amount of the original cellulose derivative. The amount of bound acetic acid in this specification is
This is a value obtained according to ASTMD-68T. The cellulose derivative of the present invention generally contains water, dimethylformamide, formamide, N-methylformamide, and N-methylformamide, although it depends on the amount of bound acetic acid.
- Amide solvents such as propylacetamide,
Easily soluble in DMSO and other sulfoxide solvents, pyridine, formic acid, acetone, water/acetone mixed solvents, etc. The dope obtained from these is
Can be used as a molding dope. For example, by dry spinning a solution obtained using water as a solvent, it is possible to produce fibers that are pollution-free and do not require solvent recovery. For example, when dissolved in formamide, a dope exhibiting optical anisotropy at a polymer concentration of about 30% by weight can be formed, and a molded article with excellent mechanical properties can be obtained from this dope. The first feature of the cellulose derivative according to the present invention is that it is obtained by dissolving cellulose in a DMSO/PFA mixed solvent and reacting this with MDA and EDA, and a cellulose with a high degree of polymerization is used as the starting cellulose. If so, the degree of polymerization will be correspondingly high. Therefore, by molding this cellulose derivative as a raw material, a molded article with excellent mechanical properties can be obtained.
The second feature of the cellulose derivative of the present invention is that since it contains a methylenedioxy chain in its molecule, the properties of the molded product can be easily changed by adding an acid or the like and heat treating it. . The third feature of the cellulose derivative of the present invention is that it has strong surface activity in a low bound acetic acid content range, for example, 8.4 to 27%, and can be applied to fields such as emulsion stabilizers. . Hereinafter, the present invention will be explained with reference to examples. Example 1 Two types of cellulose (degree of polymerization = 300 and 1000)
Each was vacuum dried at 60℃ for 7 hours, and 3g was collected.
The mixture was mixed with 100 ml of DMSO and 3 g of PFA, and stirred at a temperature of 80°C to obtain a homogeneous cellulose solution in 5 hours.
Then, excess PFA was exhausted out of the system at 80°C.
To this solution, 3.75 mg of sodium acetate was added and dissolved, and then 15 ml of MDA was added and reacted at 90° C. for 10 hours. The polymer component was recovered by precipitation in 500 ml of methanol and dried. The resulting compound was soluble in water and exhibited specific absorption in the UV wavelength range of 264-268 nm. The amount of bound acetic acid was 22.0%.
This product was also dissolved in organic solvents such as formic acid, formamide, dimethylsulfoxide, dimethylacetamide, N-methylpyrrolidone, γ-butyrolactam, and the like. The above method was repeated using various amounts of MDA. The range of water solubility of the obtained cellulose derivative is shown in Table 1 below in terms of the amount of bound acetic acid.

【table】

[Table] In the table, nothing means insoluble, and presence means soluble. No.
The derivative of 6 was dissolved in acetone and formamide. Example 2 3.0 mg of sodium acetate was added to 100 ml of the cellulose solution obtained in Example 1 to dissolve it, and 15 ml of EDA was heated at 100°C.
The mixture was allowed to react for 12 hours. The reaction was precipitated in 500 ml of methanol to recover the polymer components and dried. The resulting compound exhibits water solubility;
Its UV showed an absorption peak at 268 nm. Its IR
The figure was almost the same as that obtained in Example 1. This derivative was also soluble in organic solvents such as formic acid, formamide, dimethyl sulfoxide, dimethyl acetamide, γ-butylactone, and N-methylpyrrolidone. Example 3 Add 100 ml of the cellulose solution prepared in Example 1 to
As reaction catalysts for MDA, boron trifluoride ether complex salt, aluminum chloride, and pyridine were used separately in place of sodium acetate. First, the amount of boron trifluoride ether complex salt added was varied in the range from 0.05 ml to 0.5 ml, 15 ml of MDA was added, and the mixture was reacted at room temperature for 3 to 5 hours. The polymer component was recovered by precipitation with 500 ml of methanol, and the solubility of the product was examined, but it was not soluble in the solvent shown in Example 1. Moreover, its IR spectrum did not show any absorption characteristic of ester groups. Similarly aluminum chloride and pyridine
Add 15 ml of MDA, varying the amount added in the range from 0.01 g to 0.1 g, and let it cool at room temperature for 3 to 30 minutes.
The reaction was allowed to proceed for 5 hours. The results showed that, similar to the case of the boron trifluoride ether complex salt, the reactant did not dissolve in the solvent shown in Example 1. Even when EDA was used instead of MDA as a reactant, only sodium acetate was effective as a reaction catalyst, and boron trifluoride ether complex salt,
Aluminum chloride and pyridine were not effective as catalysts. Example 4 To 100 ml of the cellulose solution prepared in Example 1,
Sodium acetate was added in different amounts (1.5 mg and 3.75 mg) to examine the difference in reactivity to 15 ml of MDA. Example 1 when adding 1.5 mg of sodium acetate
It showed water solubility even in a region where the reaction rate was lower than the water solubility range shown in , that is, a region where the amount of bound acetic acid was low. The amount of bound acetic acid in this case was 8.4%. When we measured the ultraviolet (UV) absorption spectrum and infrared (IR) absorption spectrum of one of these samples, it showed absorption at 264 mμ in the UV (see attached Figure 1). In IR, an absorption different from that of commercially available cellulose acetate appeared at 950 cm ^-1 (see attached Figure 2). The solid line curve in FIG. 1 is the UV absorption spectrum of the cellulose derivative, and the dotted line curve is the UV absorption spectrum of commercially available cellulose acetate. In the above cellulose derivative, new absorption is observed in the region (260 to 270 mμ) showing the handmark, but not in cellulose acetate. The lower curve in FIG. 2 is the IR absorption spectrum of the cellulose derivative, and the upper curve is the IR absorption spectrum of commercially available cellulose acetate. The large difference between the upper and lower IR absorption spectra is the hand mark at 950 cm ^-1
It's in the nearby absorption band. Example 5 Two types of cellulose derivatives obtained by the method described in Example 1 (polymerization degree (DP) of raw material cellulose: 300 and
1000) dissolved in water at concentrations of 28% and 20%, respectively.
% dope was obtained. The dope was degassed under vacuum for a day and night, and the dope viscosity was measured to be 5,400 poise and 7,500 poise, respectively. The above dope was extruded from a spinning nozzle with 76 holes (diameter of each hole = 0.08 mm) into a dry cylinder controlled at 170° C. at a discharge rate of 3.0 cc/min, and dry spun. The physical properties of the obtained fibers are summarized in Table 2.

[Table] Whiteness is measured using Hitachi colorimeter EPR-type.
Calibration was performed at 400 nm and the reflectance was shown. As is clear from the table, the use of derivatives with a high degree of polymerization is more preferable in terms of the physical properties of the resulting fibers. Example 6 Derivatives listed in Table 1 of Example 1 (No. 6,
DP = 300) was dissolved in formamide to a concentration of 38% by weight, and by applying a minute shearing force, it was possible to easily obtain a dope that exhibited optical anisotropy under crossed Nicols under a polarizing microscope. This dope was defoamed under reduced pressure for a day and night, and then extruded using an extruder (inner diameter 12 mmφ) from a 0.07 mmφ, 50-hole nozzle at a discharge rate of 2.5 cc/min, and passed through a 1.8 cm air gap with methanol/water (=1 /1,
The yarn was run through a V/V) system coagulation bath and wound onto a drum. After that, it was soaked in water for a day and night, and then air-dried. Table 3 shows the performance of the obtained fibers.

[Table] As can be seen from this table, even if a derivative with the same degree of polymerization (300) as in Example 5 is used, fibers with excellent physical properties can be obtained by changing the solvent used. This means that by spinning a dope that exhibits specificity, that is, optical anisotropy, it is possible to obtain fibers with high orientation, and thus high tensile strength and initial Young's modulus.

[Brief explanation of the drawing]

FIG. 1 shows the ultraviolet (UV) absorption spectrum of the novel cellulose derivative obtained by the method of the present invention (solid line). For comparison, the UV spectrum of cellulose acetate is also shown (dotted line). FIG. 2 shows infrared (IR) absorption spectra of the novel cellulose derivative obtained by the method of the present invention (lower curve) and commercially available cellulose acetate (upper curve).

Claims (1)

[Claims] 1. Obtained by the reaction of cellulose dissolved in dimethyl sulfoxide/paraformaldehyde with methylene diacetate or ethylene diacetate, the number average number of pyranose rings in one polymer chain is 100 or more, In addition, it has a methylenedioxy chain in the pyranose ring, and the terminal thereof is substituted with an acetyl group at a rate of 8.4 to 42% in terms of the amount of bound acetic acid,
A cellulose derivative characterized by exhibiting ultraviolet absorption at 260 nm to 280 nm in a solution state. 2. The cellulose derivative according to claim 1, which is obtained by using sodium acetate as a catalyst. 3. The cellulose derivative according to claim 1 or 2, which is essentially soluble in water and other polar solvents.