JPH0536534B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to modified protein fibers, protein fiber products, and methods for producing the same. [Prior art and its problems] Silk fibers or animal hair fibers such as wool and mohair are
It is widely used as an animal-derived protein fiber. Silk fiber has excellent dyeability, moisture absorption and desorption properties, luster, and texture (touch), and has properties not found in other fibers such as synthetic fibers. However, on the other hand, there is still room for improvement in the practical performance of silk, such as wrinkle resistance, abrasion resistance, and stiffness resistance. On the other hand, animal hair fibers such as wool have a crimp shape.
Although it has excellent properties such as elasticity, hygroscopicity, and dyeability, it is inferior in shrinkage resistance, heat setting property, alkali resistance, and mechanical properties when wet. In order to improve the above-mentioned problematic properties without sacrificing the excellent practical functional properties of silk fibers or animal hair fibers, new crosslinks can be chemically introduced, monomers can be filled inside the sample, etc. Various processing techniques using chemical modification have been developed. Among the chemical processing methods for silk fibers, graft processing for the purpose of increasing the amount of silk fibers is well known. However, when increasing the weight increase rate through this grafting process, the functional properties of the silk thread, such as its durability and wrinkle resistance, often decrease, and the fine structure of the fiber, which is directly related to the functional properties of the fiber, is often reduced. There were also problems such as an adverse effect on (degree of molecular orientation, degree of crystallinity, etc.). Therefore, it is desired to develop a new processing technique that does not lose silk's original texture even after chemical processing and that causes minimal deterioration of the above-mentioned properties. In conventional grafting methods, the active site in the fiber where the processing reaction begins is not defined. Elucidating in detail the reactivity of active sites in fibers where processing reactions occur will provide basic information for developing chemical processing methods that can add new functional properties to protein fibers without losing their excellent properties. obtain. Furthermore, as mentioned above, although it is relatively easy to increase the weight increase rate using conventional graft processing techniques, the modification effect on physical properties such as texture, wrinkle resistance, and mechanical properties is generally limited. small. Given this technical background, there has been a desire for the emergence of new processing techniques for protein fibers. In order to meet such demands, the present inventors previously proposed a method of processing silk surfaces with succinic anhydride or glutaric anhydride (Japanese Patent Application Laid-Open No. 1999-1-1992).
No. 132877). The product obtained by this method has excellent wrinkle resistance and light resistance, but in the case of this product, conversely, it was not possible to efficiently perform graft processing using conventional vinyl monomers. [Problems to be solved by the invention] The present invention solves the above-mentioned problems and improves the wrinkle resistance of protein fibers or their products without adversely affecting the microstructure of the fibers. To provide a modification method for improving the thermal morphological stability and heat resistance of fibers, and to obtain a modified product that can be further grafted with a vinyl monomer, as well as wrinkle resistance and thermal morphological stability. The object of the present invention is to provide protein fibers and protein fiber products that have improved heat resistance and can be grafted with vinyl monomers. [Means for Solving the Problems] In the present invention, research has been carried out with the central objective of elucidating the physical properties of protein fibers such as silk fibers and wool, and methods of modifying them through chemical processing have also been intensively studied. As a result, by heat-treating silk protein fibers, animal hair protein fibers, or these textile products in an organic solvent containing an acid anhydride with a vinyl group, lysine, arginine, serine, and By reacting amino acid side chain moieties such as tyrosine with vinyl group-containing acid anhydrides, protein fibers and their textile products can be made to have heat resistance, thermal shape stability, and wrinkle resistance without adversely affecting the microstructure of the fibers. Through the vinyl groups introduced into the fibers, the resulting product can be grafted with a conventional vinyl monomer at a high grafting rate without causing felt shrinkage. We have discovered that it can be done easily. That is, according to the present invention, by subjecting an acid anhydride having a vinyl group to an acylation reaction at an amino acid side chain site contained in the fiber, the acid anhydride is contained in a proportion of 3 to 20% by weight based on the total fiber. Modified protein fibers and protein fiber products are provided. Further, according to the present invention, by contacting a protein fiber or protein fiber product with an acid anhydride solution having a vinyl group and heating, the acid anhydride is added to the amino acid side chain site of the fiber or protein fiber product. There is provided a method for producing modified protein fibers and protein products according to claim 1, which comprises carrying out an acylation reaction. According to the present invention, it is possible to improve various properties of protein fibers such as heat resistance and thermal shape stability without damaging the fibers or impairing the original texture characteristics of the fibers. Furthermore, since the product of the present invention has a vinyl group introduced therein, it is possible to easily perform graft processing using a conventionally known vinyl monomer via this vinyl group. Moreover, in this case, unlike conventional grafting processing performed directly on fibers,
The grafting process has the advantage that felt shrinkage does not occur and a high grafting rate can be obtained. Examples of the acid anhydride having a vinyl group used in the present invention include itaconic anhydride, aconitic anhydride, citraconic anhydride, maleic anhydride, crotonic anhydride,
Examples include acrylic anhydride and methacrylic anhydride. In addition to dimethylformamide and dimethyl sulfoxide, pyridine and a mixed solution of glacial acetic acid and acetic acid can also be used as processing solvents. The concentration of acid anhydride in the processing solvent is preferably set in the range of 5 to 30% by weight, preferably 10 to 20% by weight. The processing conditions are 30℃ in a processing solvent containing acid anhydride.
As mentioned above, it is desirable that animal hair fibers be treated at 65°C or higher, and silk fibers preferably treated at 75°C or higher for 1 hour or more. In addition, when using a solvent such as dimethyl sulfoxide that swells the fibers appropriately without adversely affecting the microstructure of the fibers, sufficient modification can be achieved even at low reaction temperatures and short reaction times. effect can be obtained. After the reaction is complete, in order to remove unreacted acid anhydride in the product, the fibers can be washed with a good acid anhydride solvent such as methanol or isopropanol, and then treated with heated acetone for 1 hour if necessary. desirable. In the present invention, the vinyl group-containing acid anhydride (hereinafter also simply referred to as anhydride) is added in an amount of 3 to 20% by weight on a dry basis, based on the protein fiber or its product (hereinafter also simply referred to as protein fiber). %, preferably from 5 to 15% by weight. If the amount of acid anhydride introduced into the reaction is less than the above range, the modification effect of the acid anhydride will be small, while if it is more than the above range, the functionality of the protein fibers, such as flexibility and wrinkle resistance, will be reduced. Note that the reaction in this case is an acylation reaction of an acid anhydride having a vinyl group to an amino acid side chain site in the fiber or textile product. In the present invention, the active sites of silk protein when reacting with anhydride are lysine, arginine, serine, and tyrosine. However, unlike wool fiber, the amounts of lysine and arginine in silk protein are minute. For convenience, the reaction mechanism between itaconic anhydride and the side chain molecules of lysine and serine molecules is schematically expressed by the following reaction formula. or (However, in the formula, S represents a silk fibroin molecule.) In addition to silk fibers, the protein fibers used in the present invention include
Includes animal hair fibers such as wool, mohair, cashmere, and wool. Further, protein fiber products include woven fabrics, knitted fabrics, etc. formed from these protein fibers. [Effects of the Invention] The method of the present invention is a chemical modification processing method that targets not only silk protein fibers but also animal hair protein fibers such as wool, mohair, cashmere, and hairless fibers, and their textile products. The problem with conventional grafted silk is that when the processing rate is increased to increase the bulking effect, various physical properties such as heat resistance, morphological stability during heating and temperature raising processes, and wrinkle resistance are impaired. Ta. According to the method of the present invention using an acid anhydride having a vinyl group, even if the amount of the acid anhydride introduced is increased, there is no adverse effect on the microstructure of the fiber, and the heat resistance, morphological thermal stability, and wrinkle resistance are improved. be able to. Furthermore, animal hair fibers, silk fibers, or their products can be processed with less deterioration of the fiber structure. Protein fibers processed according to the present invention have especially improved heat resistance, and therefore can be used as functional materials in various industrial fields including clothing and non-clothing fields. Acid anhydrides with vinyl groups react specifically with the side chain portions of amino acids such as lysine, arginine, serine, and tyrosine in protein fibers. The greatest feature of the present invention is that it is possible to reliably chemically introduce processing agent molecules having vinyl groups into protein fiber molecules without adversely affecting the microstructure of the fibers, and it is a novel chemical modification method that has not existed in the past. Since vinyl groups are highly reactive in chemical reactions, it is possible to bond epoxy compounds, which are currently used as protein fiber modifiers, to the vinyl groups that have been introduced into the fibers, or to add vinyl monomers to the protein fibers. Various modification effects can be expected by grafting. Through such modification methods, it is also possible to modify silk or animal hair fibers into functional materials with new properties. The present invention is a simple chemical processing method that involves simply contacting protein fibers or products with a solution containing an acid anhydride having a vinyl group and heat-treating them. A predetermined processing effect can also be achieved by simple processing such as impregnating fibers with a solution and irradiating the fibers with microwaves. [Example] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited only to these Examples. Example 1 A domestic silkworm silk fabric (Habutae with 14 momme weight) was used as a sample. It was immersed in a dimethylformamide solution containing 10% (w/v) itaconic anhydride, and then modified at 75°C for different times. We performed quality processing. The bath ratio was set at 1:20 by weight. After the reaction was completed, the sample was washed with methanol and further treated with acetone at 55°C for 1 hour to extract and remove unreacted acid anhydride, followed by washing with water to prepare a modified sample. This modified sample was air-dried and then dried under standard conditions (20
℃, 65% RH) was used as the measurement sample. The rate of increase in sample weight and the amount of acyl introduced when the processing reaction time was changed were determined. The results obtained are shown in Table-1.

[Table] Calculated from the amount.
Next, the molecular orientation and crystallinity of the sample were evaluated by measuring the refractive index. To measure the refractive index,
Using a polarizing microscope manufactured by Olympus, the refractive index (n) in the fiber direction and the refractive index (n) in the direction perpendicular to the fiber axis were measured by the Betzke method. The difference between the two refractive indexes was defined as the birefringence (nn) of the sample, and the value obtained by (n+2n)/3 was defined as the average refractive index. The values of birefringence (Δn) and average refractive index (nA) correspond to the degree of disorder of sample molecules and the crystallinity of the sample, respectively. The results obtained are shown in Table 2 below. Since the changes in these values before and after processing are minute, it is clear that even if itaconic anhydride treatment is performed, the change in the microstructure of the sample is extremely small. Therefore, the chemical processing method of the present invention is a chemical modification technique that does not impair the original properties of silk fibers. In addition, the control group shown in Table 2 shows the results measured using unprocessed silk fabric as a sample, and Comparative Example 1 and Comparative Example 2 are compared to Comparative Example 1 described later.
The results of measurements using samples treated with the conventional modification processing method shown in Comparative Example 2 are also shown.

[Table] The wrinkle resistance rate was measured as an evaluation of the wrinkle resistance, which is an important function in terms of practical performance, of silk fabrics (14 momme Habutae) produced with different processing times. The wrinkle prevention rate is
Measured by JIS F1509 method (Monsanto method). Table 3 shows the measurement results of the wrinkle prevention rate obtained.

[Table] As is clear from Table 3, the wrinkle resistance of silk fabrics was improved by treatment with itaconic anhydride. Comparative Example 1 Using the raw silk fabric used in Example 1 as a sample,
Methyl methacrylate graft polymerization was carried out in the following manner. Methyl methacrylate was added to an emulsified solution prepared by adding potassium persulfate as a polymerization initiator and polyoxyethylene nonyl phenyl ether as an emulsifier to a sulfuric acid acidic solvent with a pH of 2.8.
%, then add the sample and heat at 80℃.
The polymerization reaction proceeded. A processed silk fabric with a graft ratio of 13% was prepared from the change in sample weight before and after processing.
The silk threads constituting this processed fabric were taken out, and the refractive index was measured using the same method as in Example 1 to easily evaluate subtle changes in the microstructure of the fibers.
The results are shown in Table 2 above. Comparative Example 2 The raw silk fabric used in Example 1 was grafted with 2-hydroxyethyl methacrylate. Ammonium persulfate was added as a polymerization initiator to a sulfuric acid solution adjusted to pH 3.8, and a sample was further added to conduct a polymerization reaction of 2-hydroxyethyl methacrylate at a reaction temperature of 65°C, resulting in a processed silk fabric with a grafting rate of 14%. was prepared. The refractive index of the sample silk thread was measured in the same manner as in Comparative Example 1, and the results are shown in the table above.
Shown in 2. Example 2 A silk fabric was modified in a dimethyl sulfoxide solution containing itaconic anhydride. The details of the processing were the same as in Example 1, but the processing temperature was 70°C. Although the treatment temperature was 70° C., which is 5° C. lower than that in Example 1, it was confirmed from the increase in processing rate that the reaction of modification processing proceeded favorably. The results of refraction measurements of the processed silk threads confirmed that the degree of deterioration of the fiber microstructure was minimal. Example 3 A wool fiber (2/39S) that had been extracted and defatted overnight with acetone/ethanol (1:1 vol) was treated with itaconic anhydride in the following manner. 1 g of wool fiber was immersed in a dimethylformamide solution containing 10% (wt%) itaconic anhydride,
Processing was carried out at 65° C. for different times (1, 2, and 4 hours). Note that the details of the processing were the same as in Example 1. Table 4 shows the processing time of the wool fiber thus obtained, the measured value of the processing rate, and the measured value of the amount of acyl introduced.

[Table] Table 5 also shows the strength, elongation, and moisture absorption rate of the processed wool fibers.

[Table] Furthermore, Table 6 shows the maximum shrinkage peak temperature of the sample during the heating process determined by thermomechanical measurement manufactured by Rigaku Denki Co., Ltd. These thermal measurements were performed at a heating rate of 10°C/min, a sample length of 15 mm, and an initial sample load of 1.
g. The measurement was carried out in a nitrogen gas atmosphere. Further, the DSC curve of the sample determined by differential scanning calorimetry manufactured by Rigaku Denki Co., Ltd. is shown in Figure 1. In Figure 1,
Curve a shows the control (processing rate 0%), curve b,
c and d have processing rates of 9.88%, 14.0%, and 17.4%, respectively.
The results are shown for the sample. These measurements were performed at a heating rate of 10°C/min, sample weight 2.5mg, and DSC.
The measurement was carried out in a 2.5 mcal/s range and in a nitrogen gas atmosphere. As a control, in the DSC curve of (a), an endothermic peak attributed to thermal decomposition of keratin molecules appears at 232°C.
The DSC curve then shifted to the exothermic side. In the itaconic anhydride-treated sample, a central endothermic peak appeared at 250°C, about 20°C higher than the control, and the DSC curve then became flat in the temperature range of 250 to 310°C, indicating that the sample had better heat resistance than the control. It was confirmed that there was an improvement.

[Table] It can be seen that even in the high temperature range where thermal decomposition of the sample progresses partially, the heat resistance and thermal stability of the treated sample are improved compared to the control sample. Example 4 Wool fibers were modified in a dimethyl sulfoxide solution containing itaconic anhydride. The treatment temperature was 60°C. The details of the processing were the same as in Example 3. This treated wool (vinyl group content 150 mol/10 ⁵ g) and untreated wool were grafted in the following treatment bath. Methacrylamide (MAA) 20% (OWF) Ammonium persulfate 2% MAA Nonionic surfactant 0.5g/1 For graft polymerization, the temperature was gradually raised from 20℃ to 75℃ for 20 minutes, and the treatment was carried out at this temperature for 30 minutes. I went by doing this. After treatment, the grafted wool was washed with hot water. The untreated wool caused felt shrinkage during the grafting process, and the grafting rate was as low as 7.3%. In contrast, wool treated with itaconic anhydride did not shrink at all, and the grafting rate was 14.8%, about twice as high as that of untreated wool. The effect of graft processing on improving physical properties such as heat resistance and thermal morphological stability was also remarkable. Example 5 A silk fabric was modified in the same manner as in Example 1 using a mixed system in which maleic anhydride was dissolved in dimethylformamide. Almost the same amount of acyl groups could be introduced into the sample as in Example 1 using itaconic anhydride. It was confirmed that processed silk fabrics had improved heat resistance, thermal shape stability, and wrinkle resistance. According to the results of refractive index measurements, as in the case of itaconic anhydride, even if the processing rate was increased, the extent to which the microstructure of the fibers was adversely affected was extremely small.

[Brief explanation of the drawing]

FIG. 1 shows the DSC curve of wool treated with itaconic anhydride.

Claims (1)

[Claims] 1. An acid anhydride having a vinyl group is acylated at the amino acid side chain site contained in the fiber, and the acid anhydride is introduced at a ratio of 3 to 20% by weight to the whole fiber. Modified protein fibers and protein fiber products. 2. A protein fiber and a protein fiber product are brought into contact with a solution of an acid anhydride having a vinyl group and heated, thereby causing the acid anhydride to undergo an acylation reaction at the amino acid side chain site of the fiber or fiber product. The method for producing modified protein fibers and protein fiber products according to claim 1.