JPH01104852A - Composite molding knitted fabric - Google Patents

Abstract

PURPOSE: To obtain a knitted fabric excellent in impregnability with thermoplastic synthetic resin, and suitable for reinforced plastic molded products with high mechanical strength and high modulus such as mechanical parts by knitting Taslan (R) textured yarns each comprising a specific amount of heat-resistant fiber and thermoplastic organic fiber. CONSTITUTION: This knitted fabric is obtained by knitting Taslan (R) textured bulk yarns each of which is produced by Taslan (R) texturing of (A) thermoplastic organic fibers (e.g. polyethylene, nylon 6) and (B) 5-50 wt.% of heat- resistant fibers >=450 deg.C in heat resistance (e.g. aramid fibers, glass fibers), for example, through forming loops by using the component A and the component B as core.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention is suitable for molding reinforced plastic products with high strength and high elastic modulus such as automobiles and various other mechanical parts, pressure vessels, and pipes. This invention relates to a knitted fabric for composite molding.

(Prior art) For reinforced plastics made of thermoplastic synthetic resin and reinforcing fibers, it is necessary to impregnate the above-mentioned reinforcing fibers with the thermoplastic synthetic resin having a high melt viscosity uniformly and without creating voids. is necessary.

As a method to meet these demands, glass fiber strands are opened using static electricity, and thermoplastic synthetic resin powder is spread and adhered to the opened glass fibers.
Thereafter, the above-mentioned powder is melted by heating to form a tape-shaped strand (see Japanese Patent Publication No. 47-36467), and the strand of reinforcement fiber to which thermoplastic synthetic resin powder is attached is made of flexible thermoplastic material. A method of coating a synthetic resin to form a flexible strand, manufacturing a textile using the flexible strand, and then heating it to melt the powder and coating layer and form it into a plate shape (Japanese Patent Application Laid-Open No. 60-36156) (see official bulletin) is known.

(Problem to be solved by the invention) Conventionally, thermoplastic synthetic resins have been used in the form of powder, so in order to improve the impregnating properties of thermoplastic synthetic resins, it is necessary to use powders with particle sizes on the order of microns. It is necessary to make it into a fine powder, which involves opening fibers for reinforcing materials, spreading and adhering the above powder,
This requires extremely complicated processes such as melting and coating, and in order to obtain sheet-shaped reinforced plastics, it is necessary to weave resin-impregnated strands, that is, prepreg, as warp and weft yarns. Since it is harder than ordinary fiber threads, it is extremely difficult to weave and prepare it.

The present invention provides a knitted fabric for composite molding which has extremely good impregnability with a thermoplastic synthetic resin and can be easily and inexpensively molded into a reinforced plastic sheet with high reinforcement efficiency.

(Means for Solving the Problems) The knitted fabric for composite molding of the present invention is knitted using Taslan processed yarn, which is a mixture of thermoplastic organic fibers and heat-resistant fibers having a heat resistance of 450° C. or higher, It is characterized in that the content of the heat-resistant fibers is 5 to 50% by weight of the total weight.

The thermoplastic organic fibers used in this invention include polyolefins such as polyethylene and polypropylene, nylon 6,
These fibers are made of polyamides such as nylon 66, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and thermoplastic synthetic resins such as polyphenylene sulfide and polyether ether ketone.

In addition, heat-resistant fibers with a heat resistance of 450°C or higher are 450°C or higher.
It is a fiber that neither thermally decomposes nor melts at temperatures lower than °C, and examples thereof include aramid fiber, glass fiber, and carbon fiber.

In this invention, a Taslan processed yarn in which the above-mentioned thermoplastic organic fibers and heat-resistant fibers are mixed is used. In the Taslan processing, a large number of filaments are supplied in a relaxed state to a fluid turbulence region by an air jet, and the above-mentioned filaments are This is a method of forming bulky threads by forming loops and entanglements in
The size of the loop and the height of the bulk are determined by the tension of the supplied filament, the supply speed ratio, etc. In the case of this invention, it is desirable that the thermoplastic organic fiber forms a loop and the heat-resistant fiber forms a core without forming a loop. The content is 5 to 50% by weight, preferably 20 to 45% by weight, and the thickness of these fiber threads.

The supply rate of the heat-resistant fibers is determined by the use of yarn in the knitted fabric described later, etc., but the supply rate of the heat-resistant fibers is 0.05 times or more and less than 1 time, preferably 0.05 times the supply rate of the thermoplastic organic fibers.
It is desirable to set it to ~0.9 times, particularly 0.1 to 0.8 times. Further, the denier number and filament number of the heat-resistant fiber yarn to be used are preferably 100 to 1000 deniers and 10 to 100 filaments, respectively, and the denier number and filament number of the thermoplastic organic fiber yarn are preferably 100 to 10,000 deniers and 100 to 10000 deniers, respectively. 10-1
000 filament is preferred.

The textures of textiles woven using the above-mentioned Taslan processed yarn include ternary textures such as plain weave, twill weave, and satin weave.

Examples of the guiding weave include a diagonal weave, a ridge weave, a torn twill weave, and a herring twill weave. In addition, various textures can be selected and used depending on the purpose, such as coarse plain weave, leno weave, and patterned weave, which are generally used as textures for reinforcing cloth using glass fibers. In addition to using the above-mentioned Taslan-processed yarn for both the warp and weft, the above-mentioned Taslan-processed yarn is used for either the warp or the weft, preferably the warp, and it is made from the same fiber as the thermoplastic organic fiber in the Taslan-processed yarn. You may use the yarn for the weft. In addition, the above-mentioned Taslan processed yarn may be used to knit fabrics with arbitrary structures such as warp knitting, circular knitting, flat knitting, etc. In the case of warp knitting, the above-mentioned Taslan processed yarn may be used to form stitch loops. Instead, the Taslan processed yarn can be inserted by a method such as lay-in or tuck-in.

(Function) The above-mentioned knitted fabric is cut to a desired size, and a plurality of sheets are stacked to form a blank so that the weight is equal to the weight of the desired molded product. By preheating the fiber to the melting temperature of thermoplastic organic fibers, attaching it to a mold, and pressing it, a molded product of a desired shape, that is, a reinforced plastic product, can be obtained. However, if the content of the hot-smelling fiber is less than 5% by weight of the total.

If it is too small, the reinforcement efficiency in the final product will be low,
On the other hand, if it exceeds 50% by weight, the void ratio increases and is unsuitable. Note that the press pressure is 50 to 15% relative to the projected area.
0 kg/alt is required, and it is desirable to pressurize quickly in 1 to 2 seconds. Further, the temperature of the mold is preferably in the range of the melting point of the thermoplastic organic fiber or 50° C. below the melting point;
The cooling time is determined by the thickest part of the molded article.

Therefore, as a Taslan processed yarn, the feeding speed ratio of the heat-resistant fiber yarn and the thermoplastic organic fiber yarn during processing is set to 0.0.
5 or more, less than 21, preferably 0.05 to 0.9, especially 0
．． When using yarn obtained by setting the value between 1 and 0.8,
Since the thermoplastic organic fibers form loops and the heat-resistant fibers are almost linear without forming loops, the elongation of the heat-resistant fibers in the direction is further reduced, making it easier to melt and impregnate the thermoplastic organic fibers. become. However, if the above feed rate ratio is less than 0.05, it is too small and the content of heat-resistant fibers decreases, and the heat-resistant fibers form a hard core, making it difficult to melt and impregnate thermoplastic organic fibers. On the other hand, when the ratio is 1 or more, the void ratio becomes high and loops of heat-resistant fibers are formed, making it easy for the final molded product to elongate. In addition, in the case of a woven fabric, when one of the warp and weft, for example, the warp is made of the above-mentioned Taslan processed yarn, and the weft is made of only thermoplastic organic fibers, multiple pieces of the resulting woven fabric are By stacking the warp threads in the same direction, a unidirectional reinforced board can be obtained, and by stacking the warp threads in alternating directions, a diagonal laminate board can be obtained. In addition, in the case of warp knitting, if the above-mentioned Taslan processed yarn is inserted in the warp direction, a molded product that is highly strengthened in the warp direction can be obtained, and by using the warp yarn insertion stitch together with the weft yarn insertion stitch, Both directional and lateral directions are highly reinforced. In addition, in circular knitting and flat knitting, the directionality in two directions is stronger than in warp knitting, so even without inserting weft threads, when stacked in the same direction, a unidirectional reinforced board can be obtained. When stacked in different directions, a diagonal laminate is obtained.

(Example) Aramid fiber yarn (manufactured by DuPont, Kevlar 49.380 denier, 260 filament) was used as a heat-resistant fiber,
In addition, fiber threads (450 denier, 144 filaments) made of polyethylene terephthalate (intrinsic viscosity measured at 30°C in a mixed solvent of phenol/tetrachloroethane = 60/40: 0.6) were used as thermoplastic organic fibers. These were simultaneously supplied to the air nozzle for Taslan processing and processed. However, the supply speed of the heat-resistant fiber yarn is 0.789 times that of the thermoplastic organic fiber yarn, and the supply air pressure of the nozzle is 5 kg/co? , the air flow rate is set to 7.
~ m/hr, respectively, and winding was performed at a speed of 200 m/min.

The obtained Taslan processed yarn is used for warp and weft,
Warp yarn density 19.7/am, weft yarn density 19.7/am
Weave cII+ plain woven fabric, and from this plain woven fabric, lengthwise 20 cm,
A sample with a width of 20 al was cut, three sheets were stacked together to form a blank, and vacuum dried at 80°C for 16 hours under conditions of 0.1 mm Hg or less, and then preheated at 300°C.
The above laminated sheet was attached to a heated mold, and after preheating and melting under a light load for 3 to 5 minutes, hot compression molding was performed at a pressure of 50 to 70 kg/ai. Then under pressure 60
After rapidly cooling to .degree. C., the mold was opened to obtain a reinforced laminate made of polyethylene terephthalate and reinforced with aramid fibers and having a thickness of 1.5 on. The aramid fiber content in this reinforced laminate was 40%, and the void rate was 2% or less. In addition, the above laminate can be manufactured using ASTM
・When a tensile test was conducted in accordance with D.3039,
It had a tensile strength of 900 to 1000 MPa, was isotropic, and had an extremely excellent appearance.

(Effects of the Invention) The knitted fabric for composite molding of the present invention is a m-woven fabric using Taslan processed yarn that is a mixture of thermoplastic organic fibers and heat-resistant fibers. It is easier to make composites than conventional fiber threads, and it can be made using conventional knitting technology. Fabrics can be produced, and by melt-molding at a temperature higher than the softening point of the thermoplastic organic fiber, good molded products with few voids can be produced. In addition, since the two types of fibers mentioned above are finely mixed and formed into bulk by Taslan processing, melt impregnation with thermoplastic organic fibers can be easily performed, resulting in more homogeneous molding than when Taslan processing is not performed. can manufacture products.

Patent applicant: Toyobo Co., Ltd. Agent: Patent Attorney Yoshi 1) Tsukasa Ryo

Claims (1)

[Scope of Claims] [1] It is knitted using Taslan processed yarn which is a mixture of thermoplastic organic fibers and heat-resistant fibers having a heat resistance of 450°C or higher, and the content of the heat-resistant fibers is 5% of the total content. A knitted fabric for composite molding, characterized in that it accounts for ~50% by weight. [2] The knitted fabric for composite molding according to claim 1, wherein the heat-resistant fiber is an aramid fiber. [3] The knitted fabric for composite molding according to claim 1 or 2, wherein the TASLAN processed yarn has thermoplastic organic fibers forming loops and heat-resistant fibers having a substantially linear shape.