JPS5944989B2 - Composite molding method of fiber sheet and plastics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a composite molding method suitable for manufacturing molded products having a structure in which a fiber sheet is laminated on the surface of a plastic sheet or plate three-dimensionally molded into various curved surfaces. .

Conventional methods for obtaining this type of molded structure include vacuum forming or press forming a plastic sheet or plate individually, but the appearance and feel are flat, cold, and hard. It was hot.

In addition, heat embossing has been carried out on the surface of a plastic sheet or plate in advance to improve its appearance and feel, but this method is not sufficiently effective. Furthermore, as mentioned above, a fiber sheet is attached to the surface of a plastic sheet or plate after it has been individually formed. Because the threads do not stretch sufficiently, in order to adhere them to a three-dimensional curved surface, it is necessary to cut and sew fiber sheets into three-dimensional shapes and then paste them together, which is a long and complicated process. Moreover, the appearance of the finished molded product also lacked commercial value. There have also been cases where fiber sheets have been pasted onto plastic sheets or boards and then molded to improve the appearance and feel; Because it has a large recovery force, it has problems such as peeling and deformation of the molded product.

This is because the fiber sheet has low thermoplasticity at the molding temperature. The present invention was designed to eliminate the above-mentioned drawbacks when a plastic sheet or plate and a fiber sheet are bonded together and molded, as seen in the latter method, and it is possible to achieve sufficient thermoplasticity at the molding temperature. It is characterized by the use of a fiber sheet with fibers.

That is, the present invention uses highly oriented undrawn fibers with a birefringence index (△n) of 0.02 to 0.045 obtained by melt spinning polyamide as a base fabric, and has a softening point higher than that of the highly oriented undrawn fibers. A fiber sheet in which the fibers having the above-mentioned fibers are made into pile yarns, or a fiber sheet in which the above-mentioned highly oriented undrawn fibers are mainly unevenly distributed in the back layer and fibers having a higher softening point than the highly oriented undrawn fibers are unevenly distributed mainly in the surface layer is used as a plastic. This is a composite molding method that is characterized by laminating sheets or plates of steel and then thermoforming.

According to the present invention, by using an unstretched fiber-containing sheet made of polyamide spun under specific spinning conditions,
The process is simple and can be molded at low temperature and pressure, and even in molded parts with large curvature, there is no tearing, peeling, or deterioration of the appearance, and a composite molded product with an excellent appearance and texture can be obtained. be able to.

Furthermore, since the highly oriented undrawn fibers of the present invention have a large elongation, stress is uniformly distributed and there is no built-in strain, so there is no possibility of delamination or deformation of the molded product. The polyamide used in the present invention is ω-amino acid H2N
Polyamide + HN from (CH2) n-1C00H or lactam (CH2) n-1C0 → p to ω, d-diamine H2N (CH2) MNH2 and ω, d-dicarboxylic acid HOOC (CH2) Polyamide + HN from n-2C00H CH2)MNHCO(CH2)n-2C0]p
and copolyamides mainly composed of these repeating units.

However, ω, ω5 are the positions of the molecular chain ends, p is the degree of polymerization, M,
n indicates a positive integer.

As the copolymerization component, conventionally known diamine components and/or dicarboxylic acid components can be used. In order to produce undrawn polyamide fibers having a birefringence index (Δn) of 0.02 to 0.045 from the above-mentioned polyamide, it is necessary to appropriately set spinning conditions.

Normally, the birefringence (Δn) is 0.02 to 0.03 at a spinning speed of about 500 to 2000 m/min, and 2000 to 40 m/min.
At a spinning speed of 00 m/min, the birefringence (Δn) is 0,0
3 to 0,045. The birefringence (Δn) is calculated using the following formula using sodium D line (wavelength 589 mμ) as a light source and arranging filaments diagonally.

However, n = interference fringe due to the degree of orientation of polymer molecular chains γ = retardation obtained by using a Berek compensator for orientation that does not result in interference fringes λ = wavelength of sodium D line α = fiber diameter birefringence is 0, If it is less than 0.02, it is not only unstable with respect to the molding temperature, but also changes rapidly over time, resulting in an extremely short life as a fiber, thread, or fiber sheet.
If it is 5 or more, crystallization progresses rapidly and the elongation of the fiber during molding is small, making it unsuitable for molding in the present invention.

The above range of fiber physical properties is preferably selected arbitrarily within the range depending on the type, thickness, molding method, and molding temperature of the plastic to be simultaneously molded as a composite material.

Next, any sheet using these fibers or threads can be used, such as non-woven fabrics, woven or knitted fabrics, etc., but the fibers or threads and drawn fibers (for example, △NO, 6O or more) such as commonly used polyamide fibers or other sheets can be used. It is important to manufacture sheets by mixing fibers with a high thermal softening point or threads made of these fibers.

In such cases, it is preferable that the drawn fibers with a high degree of orientation, the fibers with a high thermal softening point, or the threads made of these fibers be arranged in a bent manner within the tissue.
For example, a fiber sheet can be considered in which the fibers are mainly arranged on the front surface, such as pile yarns or floating fibers of a floating structure, and the undrawn polyamide fibers of the present invention are arranged on the back surface. Such a fibrous sheet is preferable because it is possible to obtain a molded article whose surface retains the fiber form by laminating the unstretched fiber surface with the plastic surface and molding the sheet. The fiber sheet may be colored or printed in advance, and may also be subjected to treatments such as flame retardancy, stain resistance, water repellency, oil repellency, and polyurethane elasticity treatment.

Further, the above-mentioned coloring treatment and various performance imparting treatments can be performed at the fiber or thread stage, or can be performed before fiber formation. On the other hand, as the plastic sheet or plate, all commonly used thermoplastic materials such as vinyl chloride resin, ABS resin, and polyolefin resin can be used.

Plasticizers, flame retardants, antistatic agents, inorganic fillers, nucleating agents, stabilizers and the like may be added to the material of the plastic sheet as desired. In addition, the adhesive used to bond the plastic sheet or board to the fiber sheet is one that has a high affinity for the fibers and plastics, has sufficient adhesive strength, and has a suitable thermoplasticity even after curing. Preferably. Possible bonding methods include dry lamination and wet lamination, and it is also possible to use hot melt adhesives in the form of films, non-woven fabrics, and powders.

It is also possible to adhesively laminate a plastic sheet or plate with a fiber sheet at the time of molding and manufacturing. Further, methods for thermoforming the laminated sheet obtained as described above include press molding, vacuum forming, etc., and an appropriate molding temperature is used depending on the type of plastic.

The heating means may be either wet heat or dry heat. The three-dimensional structure formed by the method of the present invention has a fiber layer on the surface, so the appearance
The product has an excellent texture, and the molding process does not require excessive force; the force that causes the fiber sheet to return to its original shape after molding is almost zero, so there is no possibility of deformation or damage between the layers. No peeling occurred, and a beautiful molded product faithful to the original molding pattern could be obtained, and good results were obtained for automobile interior parts, decorative laminates for furniture, toys, and other molded products.

Examples of the present invention will be described below.

In addition, the softening point of the fiber in the present invention refers to the temperature at which the fiber becomes easily deformed rapidly when heated at a constant temperature increase rate, and was measured by the following method. When a load of 0,019/d is applied to one fiber or a bundle of several fibers and the temperature is increased at a rate of 1°C/min in air, contraction occurs when a certain temperature range is reached. is contracted so that the load remains constant.

The relationship between the dimensional change of the sample fiber and temperature at this time is made into a graph, and the temperature at which the change occurs rapidly is determined as the softening point. Example 1 Nylon-6 melting temperature 260°C, spinning speed 1200m
/min to produce a multifilament yarn (
A softening point of about 165°C was obtained.

This yarn was used as the ground part, and the pile part was thread-dyed. 210 denier/48 filament highly oriented nylon 6 multifilament drawn false twisted crimped yarn (softening point 185°C) was used for single circular knitting. A pile knitted fabric with a basis weight of 3409/m was obtained by knitting a velor structure using a machine. In this knitted fabric, highly oriented unstretched nylon-6 fibers form a ground portion to maintain dimensional stability of the knitted fabric. However, since the highly oriented drawn nylon yarn forms a pile part and is in a bent state, when it is thermoformed, the former yarn undergoes substantial elongation in the yarn axis direction during molding. In the latter case, the bent yarn simply approaches a straight line, and no essential elongation of the yarn occurs.

A commercially available two-component reactive urethane adhesive (product name: Hamatite Ichi Yokohama Goshunsha Co., Ltd.) was applied to this knitted fabric to a solid content of 30 μm, resulting in a thickness of 0,877 μm! After laminating with the vinyl chloride resin board of I, it was dried to obtain a laminate.

After heating this laminate to 160° C., vacuum forming was performed using a vacuum forming mold having a curved surface shape. The unstretched nylon fibers elongate approximately four times at this temperature, and the stress generated at that time is extremely small, allowing for easy molding even into curved shapes, and a beautiful finish with no distortion after molding. . In addition, although the nylon-6 pile fibers are elongated at the curved surface, the stress is evenly distributed, which is sufficient to prevent peeling, and there is almost no thermal deformation, resulting in a three-dimensional molded product with an excellent appearance. . This molded product was durable enough to be used as an interior panel for an automobile, and had an excellent appearance and feel. Example 2 Nylon-66 was melt-spun at a melting temperature of 296°C and a spinning speed of 1300 m/min to obtain a multifilament yarn having a birefringence of 0.022 and 220 denier/28 filaments (softening point of about 220 deC).

Claims (1)

[Claims] 1 Birefringence obtained by melt spinning polyamide (△n
) is 0.020 to 0.045 as a base fabric, and a fiber sheet made of pile yarn made of fibers having a higher softening point than the highly oriented undrawn fibers, or a back side mainly made of the highly oriented undrawn fibers. A fiber sheet comprising fibers unevenly distributed in layers and having a higher softening degree than the highly oriented undrawn fibers mainly unevenly distributed in the surface layer and a plastic sheet or plate are laminated and then thermoformed. A composite molding method of fiber sheets and plastics.