JPS591811B2 - Fiber sheet for molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a molded fabric that can be thermoformed into three-dimensional shapes with various curved surfaces, retains its fibrous form even after molding, and has an excellent appearance and feel. Regarding fiber sheets.

BACKGROUND ART Conventionally, the use of carpets made of fabric three-dimensionally formed to conform to the uneven floors of automobiles, buildings, etc. is known from Japanese Utility Model Publications No. 48-27761 and Japanese Utility Model Publication No. 50-48339.

That is, this publication discloses a molding fabric and a molding mat made of a laminate in which a synthetic resin backing layer is provided on the back side of a pile fabric. However, it has disadvantages in that excessive pressure and high-temperature heating are required for molding, and that the fabric has a large recovery force after molding, resulting in peeling and deformation of the molded product. It also has drawbacks such as not being able to stretch sufficiently along curved surfaces, resulting in breakage or peeling (other see-through development) at corners or molded areas with large curvature. Such defects are thought to be due to the low plasticity and heat elongation of the fiber sheet at the molding temperature. The present inventors have found that they can be thermoformed into three-dimensional shapes with various curved surfaces, and have excellent appearance and texture after molding.
Moreover, the present invention was achieved as a result of intensive research in order to obtain a fabric that is easily moldable and does not contain any inherent distortion that would cause deformation after molding.

That is, in the present invention, highly oriented undrawn fibers having a birefringence index (△n) of 0.02 to 0.08 obtained by melt-spinning polyethylene terephthalate or polyester mainly composed of ethylene terephthalate repeating units are used in the ground section. This is a moldable fiber sheet in which fibers having a higher softening point than the fibers are arranged in the pile portion. The fiber sheet of the present invention uses highly oriented undrawn fibers obtained by spinning polyester under specific spinning conditions for the ground part of the fabric, making the process easy to operate and can be molded at low temperature and low pressure. In addition, even in molded parts with large curvatures, there is no tearing, peeling, or deterioration of the appearance. In addition, highly oriented undrawn fibers are stable and have a large elongation, so stress is distributed evenly and there is no built-in strain, so they do not cause deformation after molding, and do not cause delamination when laminated with plastic sheets and integrally molded. There are no drawbacks that arise. Furthermore, undrawn polyester fibers with a specific △n can maintain stable and excellent elongation properties during fabric storage and dyeing processes prior to molding, and during heating during molding, and they do not undergo thermal crystallization after molding. This improves heat resistance and makes it even more stable. In addition, the pile portion of the fabric has many features such as being stable at molding temperatures by disposing fibers with a high softening point, and retaining an excellent appearance and feel even after molding. The polyester used in the present invention is a copolyester mainly composed of polyethylene terephthalate or ethylene terephthalate repeating units, and a wide range of conventionally known acid components and/or glycol components can be used as the copolymer component.

That is, examples of acid components include isophthalic acid, adipic acid, sebacic acid, etc., and examples of glycol components include propylene glycol, butylene glycol, diethylene glycol, neopentyl glycol,
Examples include cyclohexanedimethanol. It may also be a polyester using an oxyacid such as oxyethoxybenzoic acid as a copolymerization component. The content of ethylene terephthalate repeating units in the polyester is preferably 85 mol % or more from the viewpoint of stability over time, thermal stability, etc. of the polyester. From the above polyester, the birefringence (
Δn) is 0.02 to 0.08, particularly preferably 0.02
Appropriate setting of spinning conditions is required to produce highly oriented undrawn fibers of 5 to 0.07.

It can usually be obtained by high speed spinning of about 2000 to 4000 m/min. The birefringence index (△n) is calculated using a Nippon Kogaku POH type polarizing microscope using sodium D line (wavelength 589 mμ) as a light source and arranging the filaments diagonally, and using the following formula. . However, n: Interference fringes due to the degree of orientation of a single polymer molecular chain γ: Retardation determined using a Beretsk compensator for orientation that does not result in interference fringes λ: Wavelength of sodium D line (Mm) α: Fiber diameter (Mm) Further, it is preferable that the highly oriented undrawn fiber has a density of 1.35 or less when measured at 30° C. using a calcium nitrate monoaqueous density gradient tube.

If the birefringence is less than 0.02, it is not only unstable with respect to the molding temperature, but also dyeing before molding is impossible.
In addition, the lifespan of the fibers, threads, and fiber sheets is extremely short, making them unsuitable for practical use.

On the other hand, if it exceeds 0.08, crystallization will rapidly progress and the elongation of the fibers during molding will be small and unsuitable. Further, in the present invention, the high softening point fibers used in the pile portion include, in addition to ordinary drawn polyester fibers, other fibers having a high heat softening point or mixed fibers made of these fibers.

The difference in softening point between the fiber and the highly oriented undrawn polyester fiber is preferably 5°C or more, more preferably 20°C or more. A fiber sheet is formed using highly oriented undrawn polyester fibers and high softening point fibers, but any fabric such as woven or knitted fabric or nonwoven fabric may be used.

What is important here is that the fiber sheet is manufactured by disposing highly oriented undrawn polyester fibers in the ground part and distributing high softening point fibers in the pile part. As an example of such a method, high softening point fibers are arranged in the pile threads of a pile structure, the floating threads of a floating structure, etc., and the fibers are arranged in a bent shape within the fabric structure, and the elongation of the ground part during molding. Accordingly, it is preferable that the pile portion is systematically elongated. The fiber sheet may be colored or printed, and may also be subjected to treatments such as flame retardancy, stain resistance, water and oil repellency, and polyurethane elasticity processing.

The fibrous sheet thus obtained is usually laminated with a plastic sheet or plate, or both are adhered and thermoformed into the desired shape.

Examples of the plastic sheet or board include sheets or boards made of common thermoplastic plastic materials such as vinyl chloride resin, ABS resin, and polyolefin resin. Plasticizers, flame retardants, antistatic agents, inorganic fillers, nucleating agents, stabilizers, etc. can be added to the plastic material as desired. As a plastic material, high softening point fibers are selected from materials that do not damage the fiber morphology (・Materials that can be thermoformed under molding conditions.Also, adhesives that are sometimes used to bond plastic sheets and fiber sheets together) It is preferable that the agent has a high affinity with fibers and plastics, has sufficient adhesive strength, and has appropriate hot plasticity even after adhesive molding.Adhesive methods include dry lamination, wet lamination, etc. It is also possible to use a heat-melting adhesive in the form of a film or powder.

It is also possible to attach by extrusion lamination of plastic sheets without using adhesives. The fiber sheet or laminated sheet thus obtained can be easily formed into a desired shape by thermoforming such as press molding, vacuum forming, pressure forming, etc.

The heating means may be either dry heat or moist heat. Molded products made from the fiber sheet of the present invention retain the fiber morphology of the surface fiber layer, resulting in excellent appearance and texture, and can be easily molded without requiring excessive pressure during the molding process, resulting in a three-dimensional structure. Even if it is, there is no inherent strain, the force to return to the original shape is almost zero, and there is no deformation or delamination. Therefore, it is suitable for automobile interior parts, decorative laminates for furniture, toys, and other molded products.
The present invention will be explained below with reference to Examples.

Example 1 Polyethylene terephthalate with an intrinsic viscosity of 0660 measured at 30°C in a tetrachloroethane/phenol mixed solvent (6/4 weight ratio) was melted at a melting temperature of 280°C and a spinning speed of 30°C.
Melt spinning at 00 m/min, birefringence 0.034, density 1
．． 34 highly oriented undrawn multifilament yarns of 210 denier/30 filaments were obtained.

Use this thread as the ground part (210 denier/48 filament nylon 6 with thread-dyed pile part)
・Using 6 multifilament drawn false twisted crimped yarn, the fabric weight of velor structure is 3007/R with a single circular knitting machine.
A pile knitted fabric of RL was knitted.

In this knitted fabric, highly oriented undrawn polyester fibers form a ground part to maintain the dimensional stability of the knitted fabric, and also exhibit excellent elongation in the yarn axis direction during molding, allowing it to be molded well along uneven parts. On the other hand, the nylon yarn with a high softening point forms a pile part and is in a bent state within the tissue, so when thermoforming the bent yarn is stretched and approaches a straight shape, resulting in the formation of ground fibers. It can exhibit excellent extensibility along with elongation. Of course, the pile has a high softening point, so the appearance and texture will not be impaired by forming. This knitted fabric is laminated with a 0.7 mm thick ABS resin plate coated with an adhesive consisting of a saturated polyester resin (Byron 30S, Toyobo Co., Ltd.) and a hardening agent to a solid content of 20 μm.
A laminated sheet was obtained by drying.

After heating this laminated sheet to 170° C., vacuum forming was performed using a vacuum forming mold having a curved surface shape. The ground fibers elongated more than three times at this molding temperature, and the stress generated at that time was extremely small, allowing for easy molding even into curved shapes, and a beautiful finish was obtained with no distortion after molding. Although the pile fibers were elongated at the curved surface, the stress was evenly distributed, and a three-dimensional molded product with an excellent appearance was obtained without any peeling at the corners. Comparative examples in which polyurethane elastic fibers were used in place of highly oriented unstretched polyester fibers had good moldability, but had the drawback of inherent distortion and backlash after molding.

Example 2 Using the polyethylene terephthalate used in Example 1, various undrawn fibers of △n were produced by changing the spinning winding speed, and pile knitted fabrics were knitted in the same manner as in Example 1, and ABS
The resin plates were laminated and thermoformed, and the moldability (as soon as possible after fiber production) was evaluated.

The results are shown in Table-1. △NO. Fiber sheets using undrawn polyester fibers with O2 to 0.08 gave good results in terms of stability over time before molding, dyeing processability, and moldability, but in addition, Δn was 0.025 to 0.07. gave more favorable results.

Claims (1)

[Claims] 1 The birefringence index (△n) obtained by melt-spinning polyethylene terephthalate or polyester mainly composed of ethylene terephthalate repeating units is 0.02 to 0.0.
A fiber sheet for molding comprising highly oriented undrawn fibers of No. 8 arranged in the ground part and fibers having a higher softening point than the fibers arranged in the pile part.