JPH0241226A - Manufacture of molded form - Google Patents

Abstract

PURPOSE:To eliminate cutting or floating of the fiber of a knitted fabric and to mold with small radius of curvature even at the corner of a molded by so setting a molding plate to the mold as to cross all the sides of the mold at the needle wale and course of the fabric. CONSTITUTION:Knitted fabrics 1, 1 are disposed on both front and rear faces of a molding board 5 formed, for example, of a hard vinyl chloride plate, pressed to form a molding plate 6 integrally laminated with the fabric 1 and the board 5. This plate 6 is so set on the upper face of the mold 11 as to cross the needle wale W and course C of the fabric 1 at all the sides 11a, 11a,... of the mold 11. Then, the plate 6 is molded along the mold 11 by pressure molding, vacuum molding or press molding to thereby obtain a molded form. Thus, even if the fabric 1 is different in the needle wale W and course C directions of the fabric 1 in terms of elongation, the elongation of the fabric 1 is averaged in the elongating direction of the plate 6. Accordingly, conductive fiber 2 is not cut or not levitated at the corner part 16 of the mold 11 being easily elongated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing a molded article by molding a molded plate formed by integrating a knitted fabric and a molded substrate.

(Prior Art) In manufacturing a molded product by molding a molded plate formed by integrating a knitted fabric and a molded substrate, the present applicant has disclosed, for example, in Japanese Patent Application No. 61-95799, that the development magnification is large; A formed plate that can be subjected to deep drawing processing is provided.

This molded plate is a knitted fabric made of conductive fibers and a heat-melt resin having a higher heat shrinkage rate than the conductive fibers, and the conductive fibers are crimped by the heat-shrinkage of the heat-melt resin. The knitted fabric is overlaid on a molded substrate and melted and pressed to integrate it.

To manufacture a molded product using such a molding plate, set the molding plate in the mold so that the needles, needles, and courses of the knitted fabric are parallel to each side of the mold, By applying heat and pressure in this state, the molded plate was molded along the mold.

The molded product obtained by the above method has a conductive knitted fabric disposed over the entire surface, and therefore is suitable for use in, for example, semiconductor electrically insulated wire devices, etc. whose functions may be impaired by static electricity or noise penetration. Containers for packaging and transporting electronic devices, magnetic disks that are sensitive to static electricity and noise,
Suitable for use in filing cases and the like for storing and preserving recording materials such as magnetic cards.

(Problem to be solved by the invention) However, in the conventional manufacturing method, although the elongation rate of the knitted fabric is different between the needle wale direction and the course direction, the needle wale and course of the knitted fabric are Because forming plates or forming molds were set along each side for forming, in the course direction where the elongation rate is relatively high, the forming plate could be stretched along the forming die without any problem, but the relative elongation rate was If the needle wale direction is too small, the conductive fibers of the knitted fabric may be cut or the molded plate may not be molded along the mold, causing the conductive fibers to float.

In other words, knitted fabrics generally have different elongation rates in the needle/wale direction and the course direction, and the course direction often stretches more easily than the needle/wale direction. Therefore, the conductive fiber direction of the knitted fabric is When molding is performed with the molded plate centered in the mold along each side, the molded plate is greatly elongated, especially at some corners of the mold (large corners and protruding corners). This causes problems such as lifting of the fibers and breakage of the fibers in the elongated portions of the knitted fabric in the needle and wale directions. Therefore,
In conventional manufacturing methods, when the radius of curvature of a part of a corner is small, the molded plate is particularly elongated at this part of the corner, causing problems such as the above-mentioned fiber breakage. I couldn't.

The present invention solves the above-mentioned drawbacks, and its purpose is to:
To provide a method for manufacturing a molded article, in which the fibers of a knitted fabric are not cut or the fibers are not lifted during molding, and the molded article can be molded with a small radius of curvature even at a part of the corner of a mold. It is in.

(Means for Solving the Problems) The method for manufacturing a molded article of the present invention includes setting a molded plate formed by integrating a knitted fabric and a molded substrate in a mold having at least one side, and molding the molded plate. A method for manufacturing a molded article by molding it along a mold, the method comprising placing a molding plate in the mold so that the needle wale and course of the knitted fabric intersect all sides of the mold. This feature achieves the above objective.

In the present invention, a molded plate formed by laminating a knitted fabric whose constituent fibers are crimped conductive fibers and a molded substrate can be used.

The above knitted fabric is manufactured as follows. As shown in Fig. 3(a), conductive fibers 2 are prepared by twisting a filament yarn made of conductive fibers or a spun yarn made of conductive short fibers, and a fiber made of a heat-melting resin is twisted. Twisted thermofusible fibers 3 are pulled together at least one by one and twisted in opposite directions (this is referred to as -L twist) to create a plied yarn 4.
make. At this time, it is preferable to increase the number of twists in the ply twist because this increases the degree of crimp of the conductive fibers 2 obtained in the subsequent process. Furthermore, if the twisting force of the heat-fusible fibers 3 is made larger than that of the conductive fibers 2 at the stage of first twisting, the number of ply twists of the conductive fibers 2 will increase in the resulting plied yarn 4, and as above, the number of ply twists of the conductive fibers 2 will increase. This is preferable because the degree of crimp is increased. In other words, the number of ply twists of the conductive fibers 2 in the obtained plied yarn 4 is determined by maintaining the balance between the twisting force of the first twist and the twisting force of the final twist of each fiber. When the twisting force of the first twist of the fibers 3 is large, the repulsive force that tries to return to the original twist is added to the twisting force of the first twist, and the number of second twists of the conductive fibers 2 increases by that amount.

In this case, the twisting force may be increased by increasing the number of twists or by increasing the fiber diameter.

Next, the knitted fabric 1 is obtained by knitting the thus obtained plied yarn 4 using a normal knitting machine.

In particular, it is preferable that the knitted fabric 1 be knitted using a knitting machine such as a flat knitting machine, a circular knitting machine, a warp knitting machine, etc., and knitted with stockinette knitting having the highest expansion and contraction ratio as shown in FIG. Further, in the figure, it is preferable that the knitted fabric is knitted so that the distance between the needle wales W is approximately twice the distance between the courses C, since the knitted fabric L stretches almost evenly in the vertical and horizontal directions. Note that in the present invention, the ratio of the distance between the needle wales W and the distance between the courses C is not limited in any way, and the knitted fabric may be used even if it is particularly easy to stretch in one direction of the knitted fabric, for example, in the course C direction. be able to.

Next, the knitted fabric 1 thus obtained is heat-treated by passing it between heated rolls to a temperature at which the heat-fusible fibers 3 are slightly melted.

The conductive fiber 2 twisted spirally is shown in FIG. 1(b).
As shown in FIG. 2, the spacing between the helices is shrunk in the axial direction due to the thermal contraction of the heat-fusible fibers 3 in the axial direction due to the heat treatment, and the conductive fibers 2 are wound into a finely curled state. causes shrinkage. Further, slightly melting the heat-fusible fibers 3 fixes the intersections of the fibers 3 and also serves to prevent the stitches of the knitted fabric 1 from becoming loose. In this way, the knitted fabric 1 made of the twisted yarn 4 of the conductive fibers 2 and the heat-fusible fibers 3 is in a state in which the conductive fibers 2 are finely crimped in a spiral shape around the contracted heat-fusible fibers 3. Thus, the stitches become fixed.

In addition to the methods described above, conductive fibers can be crimped by using a hot-melt material with a high shrinkage rate on a part or the entire surface of a filament-based yarn made of conductive long fibers or a spun yarn made of conductive short fibers. A method may also be used in which a knitted fabric is formed using a composite yarn to which a resin is attached by dipping, and then the conductive fibers 2 are crimped by shrinking the heat-melting resin by heat treatment. In this case, the conductive fiber 2 is not finely curled in a spiral shape, but is irregularly curled. Therefore, crimping in the present invention includes states such as spiral curls, twists, zigzag shapes, etc.
It encompasses all shapes that can be stretched by applying an outward force.

Specifically, as the conductive fiber 2 in the present invention, metal fiber, carbon fiber, metal-adsorbing synthetic resin fiber, metal-plated synthetic resin fiber, etc. are used.

Here, the metal-adsorbing synthetic resin fiber is, for example, acrylic fiber that has been subjected to a reduction treatment after adsorbing copper ions, and is particularly preferable because it has excellent bending resistance. Also,
As the heat-melting resin, polyolefin resins such as polyethylene and polypropylene, polyamide resins, polyester resins, polyacrylonitrile resins, polyvinyl chloride resins, polycarbonate resins, polymethyl methacrylate resins, etc. are preferably used. In relation to the properties, a resin having a higher heat shrinkage rate than that of the conductive fiber 2 is selected. If transparency is required for the final product obtained, use a resin that has a transparency equal to or higher than that of the resin used as the molded plate 5 described in detail below, such as polyvinyl chloride resin, polycarbonate resin, or polymethyl methacrylate resin. is particularly preferably used.

As shown in FIG. 5, the knitted fabric 1 thus formed is laminated on a molded substrate 5 and fixed together to create a molded vi6. Here, the knitted fabric 1 may be embedded in a position near the surface of the molded substrate 5, or the knitted fabric 1 may be embedded in the center of the molded base vi5 in the thickness direction. Also, knitted fabric 1
may be laminated and integrally fixed to the front and back surfaces of the molded substrate 5, respectively.

In order to join the knitted fabric 1 and the molded substrate 5, as shown in FIG. By doing so,
The heat-fusible fibers 3 are melted, and the heat-fusible fibers 3 are pressed toward the molded substrate 5 to be fixed and integrally fixed thereto. As a heating method, a direct heating method using a hot plate such as a press, high frequency induction heating using the conductivity, etc. are suitably used. Further, as a pressurizing method, surface processing such as press molding or line processing such as roll forming is used. For example, when the heat-melting compatible fiber 3 and the molded substrate 5 are made of vinyl chloride resin, the heating temperature is 110 to 120°.
A range of C is preferred. Alternatively, the overlapping and heating may be performed simultaneously by feeding the molded substrate 5 in a molten state onto the knitted fabric 1 by extrusion molding. When the molded substrate 5 is a thick plastic sheet, a conductive sheet is obtained, and when it is a thin plastic film, a conductive film is obtained.

As the molded substrate 5, a plastic sheet or film made of polyolefin resin such as polyethylene or polypropylene, polyamide resin, polyester resin, polyacrylonitrile resin, polyvinyl chloride resin, polycarbonate resin, polymethyl methacrylate resin, etc. is used. In particular, plastic sheets or films made of polyvinyl chloride resin, polycarbonate resin, polymethyl methacrylate resin, etc. and having a total light transmittance of 70% or more are preferred because they can impart transparency to the final product. Further, it is preferable to use the same resin as the thermofusible resin constituting one flat cloth 1 and the molded substrate 5 in order to increase the adhesion strength between the knitted cloth 1 and the molded substrate 5.

Next, a method for manufacturing a molded product using the molded plate 6 formed as described above will be explained.

In order to manufacture a molded product from such a molded plate 6, for example, drape molding, air slip molding, straight molding,
This can be carried out by plug assist molding or the like, and the molding method and type of mold can be appropriately selected depending on the shape of the molded product, the purpose of use, economic efficiency, etc. Furthermore, although any type of mold or female mold can be used as the mold, a mold having at least one side is used in the present invention. A mold having at least one side means a mold whose planar projection shape is a polygon such as a triangle, quadrangle, or pentagon, or a semicircle or sector. To heat the molded plate, a near-infrared heater or a far-infrared heater can be used as a heat source, similar to a general vinyl chloride plate. Further, the molding temperature is preferably set slightly higher than the molding temperature of general vinyl chloride resin plates. For example, vacuum forming can be carried out at 110-120°C, and pressure forming can be carried out at 100-110°C, pressure 3-5 kg/
This can be done with c+a.

As shown in FIGS. 1 and 2, this molding plate 6 is shaped so that the needle wale W and course C of the knitted fabric l intersect with all sides 11a, Ila... of the mold 11. It is set on the upper surface of the mold 11. This intersection angle θ is preferably 30'' to 60°, particularly preferably 40° to 50°. Thereafter, the forming plate 6 is formed along the forming die 11 by air pressure forming, vacuum forming, press forming, etc. , a molded article is obtained.

In this way, by setting and molding so that the needle wale W and course C of the knitted fabric 1 intersect with each side 11a of the mold 11, the needle wale W and the course C of the knitted fabric 1 are temporarily
Even if the elongation rates are different in the wale W and course C directions, the elongation rates of the knitted fabric 1 are averaged in the elongation direction of the forming plate 6, so that, for example, the forming mold 11 is easily elongated.
The conductive fibers 2 will not be cut or lifted at the corner portions 16.

Molded products manufactured in this way are, for example, trays, containers, and packages for packaging and transporting electronic equipment such as semiconductor electrical insulated wire devices, and for storing and storing recording materials such as magnetic disks and magnetic cards. filing cases, parts for electronic/electrical equipment such as computers, word processors, etc.
Various materials such as housings, partitions used in OA rooms, clean rooms, etc. have antistatic functions,
It can be used in any application that requires electromagnetic blocking function.

(Examples) The present invention will be described in more detail below based on Examples.

[As shown in Fig. 7, knitted fabrics 1 and 1 are placed on both the front and back surfaces of a molded substrate 5 made of a hard vinyl chloride plate, and then the knitted fabrics 1 and 1 are pressed. A molded plate 6 was produced in which the molded substrate 5 was laminated and fixed together.

The forming plate 6 used here is a knitted fabric 1 that has been crimped to have a vertical dimension of 2 m and a horizontal dimension of 1.0 m, whereas the original knitted fabric has a vertical dimension of 4 m and a horizontal dimension of 1.5 m. there was.

The size of the stitches of this knitted fabric 1 is approximately 1 in width before forming.
mm x length 2 mm, and is made by twisting conductive fibers and thermofusible resin as described above.

The maximum elongation of the molded plate 6 in the contraction direction is 2 to 2.5 times the original length, and the maximum elongation in the lateral direction is 3 to 3.5 times the original length. , the molded plate 6 is more easily elongated in the horizontal direction (course direction) than in the vertical direction (in the 1 dollar run-air direction).

Next, a molded article was manufactured using the drape molding apparatus shown in FIG.

In the figure, 7 is a lamp frame that holds both ends of the molded plate 6, 8 is a heater that heats the molded plate 6 from both sides, 9 is a table, 10 is a base provided on the table 9, and 11 is this This is a mold placed on a base 10. The table 9 is provided with an intake port 13 with an air valve 12 that can be opened and closed, and the base IO is provided with a plurality of ventilation holes 14.

In manufacturing a container-shaped molded product with one side open, first, as shown in FIG. 8(a), the molding plate 6 is heated to a predetermined temperature with a heater 8, and then as shown in FIG. 8(b). Then, the clamp 7 is lowered and the molding plate 6 is disposed along the upper surface of the mold 11. Next, as shown in FIG. 8(C), by opening the air valve 12 of the table 9, the air inside the mold 11 is removed through the intake port 13 and the ventilation hole 14, and the inside of the mold 11 is evacuated. In this state, the molding plate 6 is closely deformed along the outer surface of the mold 11.

Here, the needle wale W and course C of the knitted fabric 1 of the forming plate 6 are as shown in FIG.
The forming plate 6 is set on the upper surface of the mold 11 so that it intersects all sides of the knitted fabric 1, that is, so that each fiber direction of the knitted fabric 1 intersects each side of the mold 11 at a predetermined angle. do. This crossing angle θ is preferably 30° to 60°, particularly 4
0° to 50° is preferred. Next, as shown in FIG. 8(d), after the molded plate 6 is cooled and solidified in the mold 11, the air valve 12 is closed and the inside of the mold 11 is set to normal pressure, and the clamp frame 7 is
is moved upward and the molded product 15 is taken out from the mold 11. In addition, in drape molding, the molded molding plate 6 contracts when cooled and acts to hug the mold 11, so it is preferable to provide the mold 11 with a sufficient draft angle.

Further, in order to set the molding plate 6 in the mold 11, the molding plate 6 may be moved relative to the fixed mold 11, or the mold 11 may be moved.

FIG. 9 shows the set angle (intersection angle) θ of the forming plate 6 of the mold 11 with respect to the fiber direction of the knitted fabric 1 and the corners of the molded product when molding the rectangular molded product shown in FIG. It shows the relationship with some critical radius of curvature (R dimension). In the figure, A shows the above-mentioned relationship curve in the longitudinal direction of the molded plate (needle-wale direction), and B shows the relationship curve in the width direction (course direction) of the molded plate.

As shown in the figure, as the set angle θ of the mold 11 approaches 45°, the critical radius of curvature in the width direction of the molding plate increases, but the critical radius of curvature in the longitudinal direction of the molding plate decreases. Therefore, it can be seen that by setting the mold at a predetermined angle, the critical radius of curvature of a portion of the corner of the entire molding plate becomes smaller, and the portion of the corner can be formed sharply.

In addition, in the above example, a method for manufacturing a molded product using a molded plate formed by laminating a conductive knitted fabric and a molded substrate was explained, but the present invention is not limited to conductive knitted fabrics, but can also be applied to reinforcing fibers. It can also be applied to the case of molding a molded plate formed by laminating a knitted fabric formed by the method and a molded substrate.

(Effects of the Invention) As described above, according to the present invention, even when the elongation direction of the knitted fabric is different in the longitudinal direction and the transverse direction, by equalizing the elongation rate of the knitted fabric, even deep drawn products can be It is possible to manufacture a molded product with a small radius of curvature at a portion of the corner, and it is also possible to manufacture a molded product with a complicated shape. In particular, by creating a knitted fabric using crimped conductive fibers as constituent fibers, it can be suitably used for deep-drawn packaging containers, transportation containers, etc. that require antistatic and electromagnetic blocking functions. .

Figure 1(a) is a schematic side view showing a state in which a molding plate according to an embodiment of the present invention is set on a mold and being molded;
b) Its schematic plan view, Figure 2 is its explanatory diagram, Figure 3 (a
) is an enlarged plan view of the twisted yarn constituting the knitted fabric of the present invention, FIG. 3(b) is an explanatory diagram of its function, FIG. 4 is a schematic diagram showing an example of the knitted fabric, and FIG. Perspective view, Figure 6(a)
is an enlarged plan view of the knitted fabric, FIG. 6(b) is an enlarged view of the knitted fabric showing the stretched state of the forming plate shown in FIG. 5, and FIG. Figures 8(a) to (d)
) is an explanatory diagram showing a manufacturing method according to an embodiment of the present invention in which a molded product is manufactured by drape molding, and FIG. 9 is a graph showing the relationship between the cent angle of the mold and the critical radius of corner curvature of the molded product.

DESCRIPTION OF SYMBOLS 1... Knitted fabric, 2... Conductive fiber, 3... Heat meltable fiber, 5... Molded substrate, 6... Molded plate, 11...
Molding mold.

that's all

Claims (1)

[Claims] 1. A method for manufacturing a molded article, which comprises setting a molded plate formed by integrating a knitted fabric and a molded substrate in a mold having at least one side, and molding the molded plate along the mold, the method comprising: A method for producing a molded article, which comprises setting a molding plate in a mold so that the needle wales and courses of the knitted fabric intersect all sides of the mold.