DE69410792T2 - Manufacture of dyed silk filaments - Google Patents

Description

1. Field of the invention

The invention relates to a method for producing a dyed silk thread by causing each silkworm larva to secrete a dyed silk thread. More particularly, this invention relates to a method for producing a dyed silk thread having excellent color fastness to light, washing and the like.

2. Description of the state of the art

As a typical illustrative dyeing process of silk, the following process is widely known.

First, a dye is dissolved in a small amount of boiling water and the resulting dye solution is diluted to a weight of about 50 times the weight of the silk to be dyed. Then, sodium sulfate is added to prepare a dye solution. Next, the silk previously washed with hot water is put into the solution, followed by gradually heating so that the solution boils in about 30 minutes. The solution is left to stand for about 30 minutes to achieve complete adhesion of the dye to the silk. After completion of the adhesion of the dye to the silk, the silk is taken out of the solution, followed by washing with water and drying to obtain dyed silk.

Instead of dyeing the cocoons after their formation, an attempt was made to obtain a cocoon that was already dyed during its formation.

For example, as disclosed in Japanese Patent Publication No. SHO 54-30944, it is also known to coat the spiracles of each grown larva, namely from the fourth diapause to the fifth instar, with a dye solution several times so that the dye is adsorbed to the silk glands in the larva. The larva can then secrete a silk thread from its spinneret, thereby producing a colored cocoon.

Alternatively, as disclosed in Japanese Patent Laid-Open No. HEI 3-193904, it is known to produce a dyed cocoon by immersing each silkworm larva in a dye solution to adsorb the dye onto its silk gland through the air holes, and then the larva can secrete a dyed silk thread through the spinnerets.

The preceding dyeing process, in which silk is immersed in a dye solution, requires many production steps and also requires considerable time and labor for each production step. In addition, this process requires the dye solution to be about 1/2 times the weight of the silk to be dyed. Thus, large-scale production facilities and large quantities of the dye are indispensable for this process.

Another disadvantage of the above method is the difficulty of controlling temperature and time. Without precise control, color bleeding of the silk can occur. In addition, the color shade varies considerably depending on the ratio of dye to water, making it very difficult to dye silk in a desired shade.

In the latter method, a dyed silk thread is produced by coating the air holes of each silkworm larva with a dye solution or by immersing the larva in the dye solution so that the solution is adsorbed to the silk glands in the larva, and then the larva can secrete a dyed silk thread through its spinnerets to obtain a dyed cocoon. However, the dyed cocoon thus formed has such a disadvantage that dyeing occurs not only when the cocoon is boiled but also when the boiled cocoon is treated or processed to obtain a dyed thread. There are other disadvantages in that the dyed silk thread has poor color fastness to light, washing and the like due to the use of the dye, and about 30% of the larvae die even though they are quickly dipped in the dye solution.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a dyed silk thread having excellent color fastness to light, washing and the like by a simple process without dependence on the above prior art.

The above object has been achieved by the present invention, which will be described below. The present invention provides a process for producing a dyed silk thread by absorbing a dyed solution through the air holes of each silkworm larva, and then allowing the larva to secrete the dyed silk thread through its spinneret. In this process, a solution of a polymer-bound dye is used as the dyeing solution.

According to the present invention, even when silkworm larvae are immersed in an aqueous solution of a polymer-bound dye and even when a water-insoluble pigment is used as a dye, the dyeing solution can be easily absorbed through the larva's air holes serving as respiratory organs. The reason for this easy absorption is that the pigment was dispersed or dissolved in the solution in molecular form bonded with the polymer. No silkworm larva was killed by the immersion. Upon metamorphosis into a pupa, the larva secretes a thread containing the polymer-bound dye mixed in the solution to form a cocoon. By spinning the dyed cocoon, a dyed, lustrous thread can be obtained.

Furthermore, the polymer-bound dye is mixed in a hypha before secretion and before hardening of the hypha accumulated in the body of the silkworm larva. The hypha is therefore directly dyed with the polymer-bound dye solution. This results in uniform dyeing of the secreted silk thread. In the present invention, a polymer-bound dye having excellent color fastness, particularly fastness to light and washing, is used as a dye so that the silk thread dyed therewith has excellent light fastness and is free from coloring off in the subsequent washing step. The silk thread thus obtained contains both the dye and the polymer component so that it has advantages such as gloss and improved physical properties.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described below in particular by preferred embodiments.

The polymer-bound dye solution usable in the present invention means a solution of a polymer-bound dye in neutral water, an aqueous acidic solution or an aqueous alkaline solution. The concentration of the polymer-bound dye may be in the range of preferably 0.1 to 15% by weight.

The polymer-bound dye is believed to have such a structure that the dye residue and the polymer residue are chemically bonded together in a single molecule. Many methods are known for the synthesis of the polymer-bound dye, which vary in the method for introducing the dye into the polymer and in the type of polymers applicable. These production methods of this polymer-bound dye can be roughly classified into the following groups according to the type of reaction.

(1) Processes in which mutually reactive functional groups are introduced into the dye or polymer and subsequently reacted.

As an example, a dye such as a C-(hydroxyalkyl) or N-(hydroxyalkyl) containing anthraquinone, triphenylmethane or azo dye is reacted with a reactive polymer containing carboxylic acid residue groups, acid anhydride residue groups or other reactive groups therein.

As another example, a dye having an amino or phenolic hydroxyl group is reacted with an epoxy-containing reactive polymer.

(2) Processes in which an addition-polymerizable group such as a vinyl group is introduced into a dye and the resulting dye is then homopolymerized or copolymerized with another addition-polymerizable monomer.

For example, m-aminostyrene is diazotized and then coupled with one of various priming components to develop a color. The resulting vinyl-containing azo dye is polymerized.

(3) Methods in which an addition-polymerizable group such as a vinyl group is introduced into one of the dye-forming raw materials. The resulting compound is homopolymerized or copolymerized with another addition-polymerizable monomer, followed by reacting the resulting raw material(s) to develop a color.

For example, m-aminostyrene is polymerized to produce an m-aminostyrene polymer. The resulting m-aminostyrene polymer is diazotized, followed by coupling with one of various priming components to develop a color.

(4) Processes in which a reactive condensation group is introduced into a dye and the resulting dye is subjected to cocondensation with further cocondensable monomer or precondensate thereof.

For example, an azo dye, anthraquinone dye, phthalocyanine dye or the like having one or more reactive halogen-containing groups is subjected to condensation with formaldehyde, an aminoplast resin or the like.

(5) Processes in which a condensing group is introduced into one of the dye-forming raw materials and thereafter the resulting material is subjected to co-condensation with another condensable monomer or a precondensate thereof, the co-condensate being reacted with the remaining dye-forming raw material(s) to develop a color.

For example, a priming component with one or more reactive groups is condensed with a reactive polymer, followed by coupling with one or more diazo components to develop a color.

(6) Processes in which dye residues are formed in an addition-polymerizable monomer and the addition-polymerizable monomer is then polymerized using the residues as a polymerization initiator.

In the present invention, it is preferable to use a polymer-bound dye obtained by mixing and polymerizing an addition-polymerizable monomer with the diazonium salt of a pigment, the diazonium salt of a dye, or the diazonium salt of a pigment or dye intermediate.

The term "the diazonium salt of a pigment" as used herein means, for example, the diazonium salt of a phthalocyanine pigment such as copper phthalocyanine blue or copper phthalocyanine green, a vat pigment such as anthraquinone, thioindigo, perinone or perylene, or a polycyclic pigment such as quinacridone or dioxazine, a sulfide pigment or an azo pigment such as an azo-coupled and azo condensation pigment.

On the other hand, the term "the diazonium salt of a dye" means, for example, the diazonium salt of a dye such as an azo dye, anthraquinone dye, indigoid dye, sulfide dye or phthalocyanine dye. The term "the diazonium salt of a pigment or dye intermediate" means the diazonium salt of an intermediate for the above-identified pigment or dye, for example, one obtained by introducing a diazonium salt into a known intermediate such as the diazonium salt represented by the following formula (1):

Any known addition-polymerizable monomer can be used as the addition-polymerizable monomer in the present invention. Examples include vinyl compounds such as acrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, styrene, methyl vinyl ketone, methyl vinyl ether, vinyl pyrrolidone, vinyl pyridine and isobutylene; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, methylerotonic acid, itaconic acid, maleic acid, fumaric acid and acetylenedicarboxylic acid and their derivatives such as esters, acid anhydrides, acid chlorides, acid amides, methylol acid amides and alkylmethylol acid amides; vinyl compounds such as diaminovinyltriazine and vinyl urea and their derivatives such as methylol derivatives and alkylmethylol derivatives; monomers such as glycidyl acrylate, glycidyl methacrylate and acrylglycidyl ether; Monomers containing a conjugated double bond such as butadiene, isoprene and chloroprene, monomers containing a non-conjugated double bond such as ethylene glycol diacrylate, polyethylene glycol diacrylate, diallyl phthalate and N,N'-methylenebisacrylamide; unsaturated polyesters, unsaturated fatty acids, unsaturated fatty acid alkyd resins and drying oils containing unsaturated double bonds in their molecules.

With the diazonium salt of the pigment, the diazonium salt of the dye or the diazonium salt of the pigment or dye intermediate each exemplified above, the polymerizable monomer also exemplified above and selected as desired depending on the application are mixed. The resulting mixture is then polymerized by a known method such as solution emulsion, suspension or bulk polymerization, whereby a colored polymer in which the polymer is chemically combined with the pigment dye or intermediate therefor can be obtained.

The present invention will be described below by means of Examples and Comparative Examples. All designations of "part" or "parts" and "%" mean parts by weight and percent by weight unless otherwise specified.

Example 1 (Preparation of an aqueous solution of a polymer-bound dye)

Four parts (as calculated in terms of a solid part) of a triaminocopper phthalocyanine blue hydrochloride paste were mixed with 12 parts of 35% hydrochloric acid, followed by the addition of water and ice, to obtain 130 parts of a solution.

To the resulting solution, 1.2 parts of sodium nitrite was added, followed by diazotization for 20 minutes. After completion of diazotization, excess nitrous acid was decomposed with sulfamic acid while observing the progress of decomposition with potassium iodide starch paper.

The diazonium chloride solution thus obtained was filtered and the filtrate was fed into a polymerizer. Fourteen parts of acrylic acid were fed into the polymerizer. The resulting mixture was stirred at the same temperature for 20 minutes, followed by polymerization at 65°C for 2 hours. The polymerization proceeded with foaming. After the foaming subsided, the polymerization mixture was stirred for another 2 hours. After the polymerization, 200 parts of water were fed into the polymerizer and then a polymer-bound dye thus precipitated was collected by filtration.

The polymer-bound dye thus collected was added and dissolved in a dilute aqueous solution of caustic soda so that the resulting polymer-bound dye solution was adjusted to pH 8 and had a concentration of 5%.

(Production of a dyed silk yarn)

The majority (about 100) silkworm larvae that had grown up to the fifth instar were immersed in the 5% aqueous polymer-bound dye solution prepared in this way for about 2-3 seconds.

The above immersion procedure was repeated two to five times. No larva died during these procedures.

According to these processes, the aqueous polymer-bound dye solution was absorbed through their spiracles serving as respiratory organs, accumulating the dye in their bodies. No difference was observed between the silkworm larva with the dye accumulated in their bodies as described above and an ordinary silkworm larva.

After the above operations were completed, the silkworm larvae were sericultured by a conventional method. During the metamorphosis of the larvae into pupae, each larva secreted a thread colored with the blue dye previously absorbed by the body and formed a blue cocoon.

By spinning the threads thus obtained from the cocoons, a blue silk yarn was successfully obtained. The blue silk yarn thus obtained had luster, had physical properties inherent in the copper phthalocyanine blue pigment, were much superior in light fastness to the yarn dyed with a dye, was free from color transfer, and had excellent light fastness to washing.

Example 2 (Preparation of an aqueous solution of a polymer-bound dye)

In a similar manner to Example 1, an aqueous solution of the diazonium chloride of copper phthalocyanine was obtained.

In another reactor, 14 parts of N,N-dimethylaminoethyl methacrylate, 0.6 part of polyethylene glycol nonylphenyl ether and 13 parts of water were fed, followed by stirring to obtain a monomer emulsion. To the thus obtained monomer emulsion was added the aqueous solution of diazonium chloride of copper phthalocyanine.

With stirring, 8 parts of a 5% aqueous solution of titanium trichloride was added dropwise to the solution prepared above. Accompanied by the dropwise addition, the polymerization proceeded with foaming and the temperature rose to 33°C by exothermic heat. The end point of the foaming was taken as the polymerization end. After the completion of the polymerization, a polymer-bound dye thus precipitated was collected by filtration. Five parts of the polymer-bound dye thus obtained were added to 95 parts of a 5% acetic acid solution to dissolve the latter in the foam, thereby obtaining an aqueous polymer-bound dye solution.

(Production of a dyed silk yarn)

The majority (about 100) silkworm larvae that had grown up to the fourth instar were immersed in the 2% aqueous polymer-bound dye solution prepared in this way for about 2-3 seconds.

The above immersion procedure was repeated two to five times. None of the larvae died during these procedures.

According to the processes, the aqueous polymer-bound dye solution was absorbed through their spiracles serving as respiratory organs, and the dye was accumulated in their bodies. No difference was observed between the silkworm larvae with the dye accumulated in their bodies as described above and ordinary silkworm larvae.

After completion of the above operations, the silkworm larvae were sericultured by a usual method. During the metamorphosis of the larva into pupae, each larva secreted a thread colored with the blue dye which was previously absorbed and formed a blue cocoon.

By spinning the threads from the cocoons thus obtained, a blue silk yarn was successfully obtained. The blue silk yarn thus obtained had luster, physical properties inherent in copper phthalocyanine blue pigment, was superior to the conventional dye-dyed yarn in light fastness, was free from color-off, and had excellent light fastness to washing.

Example 3 (Preparation of an aqueous solution of a polymer-bound dye)

With 6.9 parts of hydrochloric acid and 1.6 parts of sodium nitrite, 4.7 parts of a red chromogen were obtained, represented by the following formula (2):

diazotized. The reaction mixture was filtered, to the resulting filtrate was added a solution of 23.3 parts of acrylamide in 50 parts of water, followed by heating to 65ºC for 30 minutes and then stirring at 65-70ºC for 30 minutes to carry out polymerization. To the To the reaction mixture, 150 parts of water was added, the reaction product was then collected by filtration, followed by washing with methanol and then with water. The paste thus obtained was then suspended in 30 parts of water, followed by addition of 25.2 parts of a 37% aqueous formaldehyde solution. The resulting solution was adjusted to pH 9 with sodium carbonate, followed by methylol formation reaction at 60-65°C for one hour. The red solution thus obtained was filtered, and the filtrate was poured into 200 parts of methanol to precipitate the polymerization product. The precipitate thus obtained was collected by filtration, the filtrate was washed again with methanol and then with ethyl ether, followed by air drying, to obtain 27.7 parts of a red polymer-bound dye.

Five parts of the thus obtained red polymer-bound dye were dissolved in 95 parts of water to obtain an aqueous polymer-bound dye solution.

(Production of a dyed silk yarn)

A large number (about 100) silkworm larvae that had grown up to the fifth instar were immersed in the 5% aqueous polymer-bound dye solution prepared in this way for about 2-3 seconds.

The above dipping procedure is repeated two to five times. None of the larvae died during these procedures.

According to the processes, the aqueous polymer-bound dye solution was absorbed through their air holes serving as respiratory organs, whereby the dye was taken up into their bodies. No difference was found between the silkworm larvae with the dye taken up into their bodies as described above and the ordinary silkworm larvae.

After completion of the above operations, the silkworm larvae were sericultured by an ordinary method. During the metamorphosis of the larva into pupae, each larva secreted a thread dyed red with the dye previously absorbed and formed a red cocoon. By spinning the threads from the cocoons thus obtained, a red silk yarn was successfully obtained. The red silk yarn thus obtained had luster, physical properties inherent in the azo pigment, was superior in light fastness to the conventional dye-dyed yarn, was free from color transfer and had excellent light fastness to washing.

Claims (4)

1. A process for producing a dyed silk thread by absorbing a dyeing solution through the air holes of each silkworm larva, followed by allowing the larva to secrete the dyed silk thread through its spinneret, characterized in that a solution of a polymer-bound dye is used as the dyeing solution. 2. The method of claim 1, wherein the solution of polymer-bound dye has a concentration of 0.1 to 15 weight percent. 3. The process of claim 1, wherein the polymer-bound dye is obtained by mixing and polymerizing the diazonium salt of a pigment, a dye or a pigment or dye intermediate with an addition-polymerizable monomer. 4. The method of claim 1, wherein the polymer-bound dye solution is absorbed through the air holes of each silkworm larva by immersing the silkworm larva in the polymer-bound dye solution 2 to 5 times for 2 to 3 seconds each.