JPS6331571B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyester sewing thread for high-speed sewing that has high strength and excellent heat resistance. Polyester fiber has high strength and high modulus,
Since it also has good color fastness, it is widely used as a material for sewing thread. However, polyester fiber sewing thread has a melting point of 250 to 265°C at most, and is not suitable for high-speed sewing. In other words, during high-speed sewing, the sewing machine needle reaches a high temperature of 300°C or higher, and during sewing, the upper thread and lower thread become entangled in the fabric being sewn. When the bobbin thread rubs against the thread and the entangled portion reaches a high temperature, the polyester fibers melt and the strength of the sewing thread decreases or the thread breaks. Therefore, attempts have been made to solve these problems.
For example, attempts have been made to improve the smoothness of the oil or increase the amount of oil adhered, but this has not yet reached the point of achieving high-speed sewability. In addition, attempts have been made to blend polyester and cotton to improve heat resistance, but the heat resistance of cotton is insufficient and satisfactory high-speed sewing performance cannot be obtained, and if cotton is blended, dyeing may occur. There are also drawbacks such as a decrease in fastness. In other words, the biggest drawback of polyester sewing thread is
As mentioned above, it melted during sewing. In order to improve this melting phenomenon, it is effective to construct the sewing thread from a spun yarn having a large amount of fluff on the surface layer of the yarn. However, even if such a spun yarn is used, once melting occurs, the melting will easily propagate to the inner layer of the sewing thread, causing yarn breakage. The inventors
Even if non-melting fibers are used to prevent the spread of this melted portion, cotton fibers and rayon fibers will deteriorate in strength when the temperature reaches 300°C or higher.
The present invention was developed based on the discovery that during high-speed sewing, the unmelted fibers are cut due to the applied tension, and that the function of preventing the fused portion from spreading is not sufficiently achieved. That is, the present invention provides polyester staple fibers having a strength of 6.5 g/de or more, and a polyester staple fiber having a strength of 2 g/de or more after heat treatment at a temperature of 300° C. for 1 minute, and which has a breaking elongation greater than the cutting elongation of the polyester staple fiber. It consists of heat-resistant fibers having a cutting elongation, and contains 10 to 50% by weight of the heat-resistant fibers based on the total weight,
A polyester sewing thread for high-speed sewing is characterized in that it is composed of a blended yarn in which the proportion of the heat-resistant fibers in the cross section is 10% or more of the total number of constituent fibers. The present invention will be explained in detail below. The polyester short fibers used in the sewing thread of the present invention need to have a high strength of 6.5 g/de or more. If the strength is less than 6.5 g/de, the strength of the sewing thread will not be sufficiently high, resulting in a decrease in seam strength, which is undesirable. Next, the heat-resistant fibers used in the present invention include:
The strength after processing for 1 minute at a dry heat temperature of 300℃ is 2.
It is important to use a material with a ratio of g/de or higher.
If the strength under these conditions is less than 2 g/de, the heat-resistant fibers will break in the sewing thread that is exposed to high temperatures during high-speed sewing, and cannot act as block fibers to prevent the propagation of melting of the polyester fibers. Furthermore, as a characteristic necessary for the heat-resistant fiber used in the present invention, its elongation at break must be greater than the elongation at break of the short polyester fiber. In other words, in order for the yarn obtained by blending heat-resistant fibers to efficiently utilize the high strength of polyester short fibers, the elongation of the polyester should be made smaller so that when the sewing thread is subjected to tension, , the strength of the polyester is greater and contributes to the strength of the sewing thread. If the elongation of the heat-resistant fibers is low, the heat-resistant fibers will be cut first when the sewing thread is pulled, and the strength of the short polyester fibers and the heat-resistant fibers cannot be utilized efficiently. Heat-resistant fibers with such features include:
Preferred examples include fibers made of polymetaphenylene isophthalamide, and fibers made of a polymer obtained by blending the polymetaphenylene isophthalamide with polymethaxylylene isophthalamide. In particular, in the case of fibers made of the latter blended polymer, there was almost no decrease in strength after heat treatment at 300°C for 1 minute, with a strength of 3.5g/de
In addition, the elongation at break is 38.5%, and by using it in combination with short polyester fibers with an elongation at break of 20%, there is little loss in strength due to blending, and it functions well as the sewing thread of the present invention. You can. Furthermore, in the sewing thread of the present invention, the mixing ratio of the heat-resistant fibers is required to be 10 to 50% by weight of the total weight, and the amount of the heat-resistant fibers is relative to the total number of constituent fibers in the cross section. The number of components must be 10% or more. When the mixing ratio of the heat-resistant fibers is less than 10%, the amount of heat-resistant fibers is small, so the role of preventing melted polyester and stopping its propagation to the inside (blocking effect of heat-resistant fibers) is sufficient. Not, but
On the other hand, the content of polyester short fibers in which the mixing ratio exceeds 50% is relatively reduced, and the strength of the sewing thread is greatly reduced, making it impossible to obtain sufficient strength. It is necessary that polyester staple fibers account for 50% or more of the entire sewing thread. Furthermore, the ratio of the number of heat-resistant fibers to the total number of fibers traversing the thread must be 10% or more. Further, it is desirable that the heat-resistant fibers are uniformly dispersed (randomly or mixedly distributed) in the traverse. If the ratio of the number of constituent fibers is less than 10%, the heat-resistant fibers will not be uniformly dispersed in the cross section, and the number of fibers will be small, so that the blocking effect of the heat-resistant fibers will not be sufficiently achieved. The polyester sewing thread thus obtained can prevent the molten polyester from propagating inside the thread even if the polyester fibers melt during high-speed sewing, and can prevent thread breakage due to melting, greatly increasing sewing efficiency. It can be applied to. Examples will be explained below. Example Sample A Single fiber denier 1.1 de, cutting strength 7.4 g/de,
A fiber made of a polymer blend of 80% by weight polyester short fibers with a cutting elongation of 18% and a boiling water shrinkage rate of 1.2%, and a heat-resistant fiber of polymethaphenylene isophthalamide and polymethaxylylene isophthalamide in a ratio of 8:2. and 20% by weight to obtain a yarn of 60 count (cotton yarn count) with a twist coefficient α = 3.5 (S twist), and three of these yarns are aligned.
A sewing thread was prepared by applying a final twist to 90% of the first twist (Z twist), then dyeing at a temperature of 130°C, and then applying a silicone oil agent in an amount of 3% based on the total weight of the thread. The polyester fiber in this yarn has a breaking strength of 7.2 g/de and a breaking elongation of 19.5%, while the heat-resistant fiber has a breaking strength of 3.1 g/de and a breaking elongation of 19.5%.
It was 38%. Furthermore, the heat-resistant fiber is heated to a temperature of 300
When the strength was measured after being treated at ℃ for 1 minute, the cutting strength was 3.1 g/de, with no change at all. still,
The proportion of heat-resistant fibers in this sewing thread is
It was 20%. This thread was tested for sewing at high speed and the results shown in Table 1 were obtained. Sample B Using only the short polyester fibers used in Sample A, sewing thread with the same number of twists and count was made, which was dyed at a temperature of 130°C and then treated with an oil agent under the same conditions as Sample A. The results of the high-speed sewing test for this thread are the first
Shown in the table. Sample C Sewing thread was made under the same conditions as Sample A, except that 20% by weight cotton fiber was used in place of the heat-resistant fiber used in Sample A, and a high-speed sewing test was conducted. The results are shown in Table 1.

[Table] As is clear from Table 1, in Sample A (Example) using heat-resistant fibers, the continuous operation time due to high speed rotation is significantly improved.

Claims (1)

[Claims] 1 Polyester staple fibers having a strength of 6.5 g/de or more and polyester staple fibers having a strength of 2 g/de or more after heat treatment at a temperature of 300°C for 1 minute and a breaking elongation greater than the breaking elongation of the polyester staple fibers. short fibers containing heat-resistant fibers made of metaphenylene isophthalamide, containing 10 to 50% by weight of the heat-resistant fibers based on the total weight, and containing the heat-resistant fibers based on the total number of fibers in the cross section. A polyester sewing thread for high-speed sewing, characterized in that it is composed of a blended yarn in which the number of fibers is 10% or more.