JP4647430B2 - Method for producing aromatic polyamide fiber for reinforcing thermosetting urethane resin belt - Google Patents

Description

  The present invention relates to an aromatic polyamide fiber for reinforcing a resin belt, and more particularly to a method for producing an aromatic polyamide fiber suitably used for reinforcing a resin belt of an OA device or the like having excellent positioning accuracy.

  The timing belt, the V belt, the flat belt, and the like, which are power transmission belts, use fiber cords to suppress the expansion of the resin serving as the base and reinforce the strength. As the fiber cord, polyester, glass, aromatic polyamide fiber, and the like, which are high modulus fibers, are generally used. Among them, aromatic polyamide fibers are widely used because of their excellent flexibility and high modulus. In particular, small diameter pulleys are frequently used in office systems and precision machines such as OA equipment, and it is known that aromatic polyamide fibers having excellent bending resistance are particularly suitable than rigid glass fibers (for example, Patent Document 1, Patent Document 2, etc.).

  However, in the past, when using such a resin belt, a tensioner was used to keep the belt tension constant. However, in recent years, in order to reduce the size of the device and reduce the cost, the tensioner is omitted. The layout is increasing. The fixed layout between the shafts is required to have a small dimensional change due to aging or the like, but the aromatic polyamide fiber has a problem that the aging change due to moisture absorption is large.

  Also, in OA equipment, especially printers, the position of the resin belt for operation control is important because the printing position is shifted and normal printing cannot be performed with a little play. There has been a demand for a reinforcing fiber with a small amount.

JP 54-135954 A JP-A-9-159000

  It is an object of the present invention to provide a method for producing an aromatic polyamide fiber having excellent dimensional stability as a resin belt reinforcing fiber, in particular, dimensional stability in the length direction due to humidity.

In the method for producing an aromatic polyamide fiber for reinforcing a thermosetting urethane resin belt according to the present invention, an aromatic polyamide fiber is impregnated in an aqueous solution having a blocked isocyanate component of 90% or more, and heat treatment is performed at a temperature higher than the dissociation temperature of the blocked isocyanate. It is characterized by that. Furthermore, the dissociation temperature of the blocked group of the blocked isocyanate is 100 ° C. or higher and 200 ° C. or lower, the melting point of the blocked isocyanate is 5 ° C. higher than the block dissociation temperature, and the melting point of the isocyanate after the block dissociation is block dissociated. The temperature is preferably 3 ° C. or more lower than the temperature, and it is preferable to perform treatment with a water-soluble epoxy after the heat treatment.

Also, the aromatic polyamide fibers, it is co polyparaphenylene-3,4'-diphenylene terephthalamide and, it is preferable tree fat belt is for OA equipment.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the aromatic polyamide fiber excellent in dimensional stability as a fiber for resin belt reinforcement, especially the dimensional stability of the length direction by humidity is provided.

  The aromatic polyamide fiber used for the aromatic polyamide fiber for reinforcing a resin belt of the present invention is generally called an aramid fiber, but a para-aramid fiber excellent in strength is particularly preferable. Specific examples of such fibers include, for example, polyparaaminobenzamide, polyparaphenylene terephthalamide, polyparaaminobenzhydrazide terephthalamide, polyterephthalic acid hydrazide, polymetaphenylene isophthalamide, and copolymers thereof. Mention may be made of fibers. In particular, a copolymer type copolyparaphenylene 3,4'-oxydiphenylene terephthalamide fiber (“Technola” manufactured by Teijin Techno Products Co., Ltd.) having high bending fatigue is more effective as the fiber used in the present invention. .

  The single yarn fineness of the aromatic polyamide fiber used is preferably 4 dtex or less, more preferably 0.5 dtex or more and 3 dtex or less. If the single yarn fineness is too large, it will be difficult to exert fiber strength, and if the single yarn fineness is too small, the strength utilization rate when they are brought close to each other tends to decrease. The total fineness is preferably in the range of 100 to 1000 dtex. The number of twists is preferably 80 T / 10 cm or less from the viewpoint of effectively utilizing strength, and more preferably used without twisting in order to improve dimensional stability.

  The production method of the present invention is a production method in which such an aromatic polyamide fiber is impregnated in an aqueous solution containing a blocked isocyanate as a main component and heat-treated at a temperature higher than the dissociation temperature of the blocked isocyanate.

  The blocked isocyanate used in the present invention is composed of a blocked polyisocyanate compound, and is an addition reaction product of a polyisocyanate compound and a blocking agent. It will give birth. An aqueous solution containing a blocked isocyanate as a main component means that the main component other than water in the aqueous solution is a blocked isocyanate component, preferably 50% or more, most preferably 90% or more of the total solid content. It is to be. Surprisingly, the treatment of the aromatic polyamide fiber with the blocked isocyanate surprisingly reduced the dimensional stability, particularly the dimensional change due to humidity. The reason is not clear, but it is presumed that this is because isocyanate reacts with the water adsorption site of the aromatic polyamide fiber to suppress water adsorption.

Here, the dissociation temperature of the blocked isocyanate is preferably 100 ° C. or higher and 200 ° C. or lower, more preferably 120 to 180 ° C. By taking such a dissociation temperature, it becomes possible to process without impairing the physical properties of the aromatic polyamide fiber. Here, the dissociation temperature is a temperature at which the blocking agent of the blocked isocyanate is dissociated, and a temperature increase rate of 10 ° C. is used in a N ₂ gas atmosphere using a TG / DTA simultaneous measuring device in which a differential thermal analyzer and a thermogravimetric measuring device are combined. It is the peak temperature of the DTA curve when the temperature is raised to 300 ° C. at a time / minute.

  Further, the melting point of the block isocyanate is preferably 5 ° C. or more higher than the block dissociation temperature, and the isocyanate melting point after the block dissociation is preferably 3 ° C. or more lower than the block dissociation temperature. Heat treatment can be effectively carried out by using a blocked isocyanate having such a melting point.

  Here, as a polyisocyanate compound which becomes a part of the block polyisocyanate, an isocyanate group of tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, tris (hexamethylene diisocyanate), tris (hexamethylene diisocyanate) is used. Examples thereof include polycondensates bonded in a chain, polyisocyanates such as polymethylene polyphenyl isocyanate and triphenylmethane triisocyanate. The blocking component is preferably a blocking agent having one or more active hydrogen atoms. For example, phenols such as phenol, thiophenol, cresol and resorcinol, aromatic secondary amines such as diphenylamine and xylidine, pyrazole, Examples thereof include cyclic amines such as dimethylpyrazole, phthalimides, lactams such as caprolactam and valerolactam, oximes such as acetoxime, methyl ethyl ketoxime and cyclohexanone oxime, and acidic sodium sulfite.

  Among these, the blocked isocyanate suitably used in the present invention includes a compound obtained by blocking an isocyanate polycondensed using diphenylmethane diisocyanate.

  The total solid concentration in the aqueous solution mainly composed of blocked isocyanate used in the present invention is 1 to 30% by weight, preferably 1.5 to 20% by weight, and more preferably 2 to 15% by weight. Is preferred. If the total solid content concentration is too low, the surface tension of the aqueous solution increases, the uniform adhesion to the fiber surface decreases, and the amount of solid adhering to the blocked isocyanate tends to decrease, thereby reducing the humidity dimension stabilizing effect. is there. On the other hand, when the aqueous solution solid content concentration is too high, not only is the production cost disadvantageous, but the amount of blocked isocyanate solid content increases too much, so that the agent falls off during processing, and the workability tends to decrease. It is in.

  In the production method of the present invention, the heat treatment is thereafter performed, but the solid content attached to the aromatic polyamide fiber after the heat treatment is preferably in the range of 0.1 to 10% by weight, more preferably 0.3 to 7% by weight. It is preferable that it is the range of these. In order to control the amount of solids adhered to the fiber, means such as squeezing with a pressure roller, scraping with a scrubber, blowing off with air blowing, suction, tapping with a beater, etc. can be adopted, and the amount of adhesion is increased. Or it can be applied multiple times to ensure uniformity. At this time, the heat treatment conditions are preferably 130 to 200 ° C. and 180 to 240 minutes.

  In the production method of the present invention, in order to improve adhesiveness, it is preferable to further treat the aromatic polyamide fiber with a water-soluble epoxy after heat treatment. It is possible to further improve the adhesive force with the resin due to the synergistic effect with the block polyisocyanate.

  Moreover, it is preferable that it is a thermosetting urethane resin as resin to reinforce. In combination with an aromatic polyamide fiber, flexibility and adhesion can be balanced with extremely high performance.

  The aromatic polyamide fiber for reinforcing a resin belt obtained by the production method of the present invention is excellent in dimensional stability and can be suitably used for various power transmission belts such as a timing belt, a V belt, and a flat belt. It is preferably used for resin belts for OA equipment, particularly printers, which greatly change in humidity due to air conditioning and cope with bending with high curvature.

Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the characteristic in an Example was performed with the following measuring method.
(1) Humidity dimensional change The sample cord was immersed in softened water for 48 hours or more, and water was saturated. This sample was sandwiched between chucks, applied with a load of 0.011 g / dtex, and allowed to stand at room temperature under a nitrogen stream until there was no dimensional change. The amount of dimensional change during the drying process was measured to determine the humidity dimensional change.

[Example 1]
An aqueous solution mainly composed of blocked isocyanate having a solid component concentration of 20% was prepared by diluting a methyl ethyl ketoxime block of diphenylmethane diisocyanate (manufactured by Meisei Chemical Co., Ltd., DM6011) with softening water. The dissociation temperature of the blocked group of the blocked isocyanate was 150 ° C., and the melting point of the isocyanate after the dissociation of the blocking group was 37 ° C.
Meanwhile, an aromatic polyamide fiber (manufactured by Teijin Techno Products Co., Ltd., trade name Technora), a non-twisted cord made of 440 dtex / 263 filament multifilament yarn was prepared.

The cord was immersed in the aqueous solution using a contributor processing machine (tire code processing machine manufactured by CA Ritzler Co., Ltd.), then dried at a temperature of 130 ° C. for 2 minutes, and subsequently at a temperature of 240 ° C. Heat treatment was performed for a minute. On the obtained treatment cord, 3.0% by weight was adhered as a solid content of the treatment agent. The humidity dimensional change of the treated cord was measured and listed in Table 1.
The obtained treated cord was treated with a water-soluble epoxy and used for reinforcing a thermosetting urethane resin to obtain a printer belt. Excellent adhesion and dimensional stability.

[Example 2]
In Example 1, the process similar to Example 1 was performed except the solid component density | concentration of the methyl ethyl ketoxime block body of diphenylmethane diisocyanate having been 5%. In this case, the solid component adhesion amount was 0.8%. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, it carried out like Example 1 except having performed water dipping instead of the processing agent. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, the change in humidity dimension was measured without the agent treatment. The results are shown in Table 1.

Claims (6)

A method for producing an aromatic polyamide fiber for reinforcing a thermosetting urethane resin belt, comprising impregnating an aromatic polyamide fiber in an aqueous solution having a blocked isocyanate component of 90% or more and heat-treating the block isocyanate at a dissociation temperature or higher. . The method for producing an aromatic polyamide fiber for reinforcing a thermosetting urethane resin belt according to claim 1, wherein the dissociation temperature of the block group of the blocked isocyanate is 100 ° C or higher and 200 ° C or lower. The thermosetting urethane resin belt according to claim 1 or 2, wherein the melting point of the blocked isocyanate is 5 ° C or more higher than the block dissociation temperature, and the melting point of the isocyanate after block dissociation is 3 ° C or more lower than the block dissociation temperature. A method for producing an aromatic polyamide fiber for reinforcement. The method for producing an aromatic polyamide fiber for reinforcing a thermosetting urethane resin belt according to any one of claims 1 to 3, wherein the aromatic polyamide fiber is copolyparaphenylene 3,4'-oxydiphenylene terephthalamide. . The method for producing an aromatic polyamide fiber for reinforcing a thermosetting urethane resin belt according to any one of claims 1 to 4, wherein the heat treatment is followed by treatment with a water-soluble epoxy. The method for producing an aromatic polyamide fiber for reinforcing a thermosetting urethane resin belt according to any one of claims 1 to 5 , wherein the resin belt is for OA equipment.