JPH0453696B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a molded article with a skin, which is formed by laminating a decorative, heat-insulating, or reinforcing skin on the surface of a plastic base material. [Prior art] When blow molding a hollow body by extruding a parison into a split mold and pressurizing fluid into the parison, blow molding is performed with a fiber sheet placed between the split mold parison and the parison. A method for manufacturing a molded article with a skin by closely adhering a parison and a fiber sheet is known from JP-A-57-49534. [Problems to be Solved by the Invention] According to the above method, a flat fiber sheet is brought into close contact with the parison and simultaneously formed into a three-dimensional shape. Although this method has the effect of omitting the step of laminating it on a plastic base material, it has been found from various experiments that the following problems occur on the other hand. (1) When a flat fiber sheet is brought into close contact with a parison and simultaneously molded into a three-dimensional shape by blow molding, the fiber sheet itself stretches apart, so in areas with a high blow ratio, the three-dimensional shape of the cavity surface is faithfully reproduced. This resulted in a problem of so-called molding defects. For example, when trying to mold the corner A3 of the protruding surface 73 of the skinned molded product 70 as shown in FIG. 13 to have a radius of curvature of 1 mm, the cavity surface of the mold is also formed to have a radius of curvature of 1 mm at the corresponding portion. However, conventional methods are inferior in reproducing three-dimensional shapes, and can only produce skinned molded products in which the radius of curvature of the corners of the protruding surface is 3 mm or more. (2) In addition, if a knitted fabric with excellent elasticity is used as the fiber sheet and the knitted fabric and parison are formed into a three-dimensional shape, the reproducibility itself can be solved to some extent, but on the other hand, the fiber sheet made of knitted fabric can be blown. There is a tendency for extreme elongation in areas where the ratio is high; for example, in a molded product with a skin as shown in Figure 13,
The blow-molded plastic base material near the corner A3 passes through small gaps in the fiber sheet and is exposed on the outer surface of the fiber sheet as a pattern of many speckled foreign objects, causing a problem that impairs the appearance characteristics of the molded product with skin. As a result, the original purpose of laminating a skin for decoration, insulation, or reinforcement could not be fully achieved. The present invention is intended to solve the above-mentioned problems, and aims to produce a molded article with a skin that is excellent in three-dimensional shape reproducibility and appearance characteristics. [Means for Solving the Problems] The present invention provides for a mold having a cavity surface formed into a desired three-dimensional shape and a parison of thermoplastic plastic in a plasticized state, so that the basis weight is between 80 and 80.
A nonwoven fabric of 500 g/m ² and a tensile strength of 10 Kg/cm ² or more is placed, then the parison is expanded, the parison and the nonwoven fabric are bonded together by thermocompression, and the mold is formed into a three-dimensional shape along the cavity surface of the mold. The present invention relates to a method for manufacturing a molded product with a skin, characterized in that the molded product is cooled and solidified while maintaining its condition. Molded product with skin: A molded product that is obtained by blow molding or pressure forming a plasticized parison in a cylindrical or sheet shape. It constitutes. Examples of molded products with skins include portable bags and interior materials for automobiles, but other products include automobile parts such as tanks, ducts, cases, housings, trays, and containers, light electrical parts,
Can be used for furniture parts and a wide range of fields. Furthermore, in terms of structure, it has at least two layers: a thermoplastic plastic as a base material and a nonwoven fabric as a skin. Thermoplastics: low density polyethylene, high density polyethylene, polystyrene, polyvinyl chloride, polypropylene,
A general term for thermoplastic plastics that can be blow molded or pressure molded, such as polyamide, polyacrylonitrile, polycarbonate, ethylene-vinyl acetate copolymer, polyphenylene oxide, and polyacetal (hereinafter referred to as plastic). In addition, two or more types of thermoplastic plastic materials may be mixed, silica, mica, talc, calcium carbonate, etc.
Fillers such as glass fiber and carbon fiber, plasticizers, stabilizers, colorants, antistatic agents, flame retardants,
A foaming agent or the like may also be mixed in if necessary. Non-woven fabric: A fabric-like product made by stacking fibers in parallel or alternately or randomly scattering them to form a web, and then joining the fibers that have become a web. The main manufacturing methods for nonwoven fabrics are (1) a dry method in which raw cotton for spinning is made into a short fiber web using a spinning card or a random waver using air flow; (2) extremely short chemical fibers and synthetic fibers are dispersed in water. Depending on the process, the web is made and bonded using adhesive fibers in the web, or by adding an adhesive. (3) The filaments coming out of the spinning nozzle are directly randomly distributed. There is a spunbond method in which the web is bonded by dispersion and accumulation. In addition, dry methods also include (a) chemical bonding using resin binder liquid, powder adhesive, low melting point fibrous adhesive, etc., and (b) needle punch method, static bonding method, etc. There are (c) those that mainly involve mechanical bonding, such as spunlace, and (c) those that combine chemical and mechanical bonding. Needle-punched cloth obtained by the needle-punching method has lower strength and higher elongation than woven cloth, and is severely deformed in any direction, so it is necessary to improve the strength of the cloth and stabilize its dimensions. . A method that takes into account the above points is a method in which a binder is bonded to a punched cloth, and No. 14.
As shown in the figure, overlap the web 81 and base fabric 82 and
There is something to punch. The thread used for the base fabric is, for example, 66 nylon: (5-15) denier x (60
~120) mm, 6 nylon: (3~30) denier x
(60-90) mm, heat-resistant nylon: (5-10) denier x (50-90) mm, polyester: (3-5) denier x (50-100) mm, polyacrylonitrile: (3
~6) Fineness is 3, such as denier x (50-90) mm
~15 denier fibers staple spun yarn with a length of about 2 to 5 inches, bundled with thin flexible filaments For example, 66 nylon: approximately 6 denier x (150 ~
200 pieces) = approx. 900-1200 denier / 1,6 nylon: approx. 9 denier x (20-100 pieces) = approx. 180-900
Denier/1, Polyester: Approximately 5 denier
(30-200 pieces) = approx. 150-1000 denier/1, polyacrotrile: approx. 2 denier x (100-400 pieces) =
Multifilament such as approximately 200-800 denier/1 or 66 nylon: 300-1100 denier/
1, 6 nylon: 300-1100 denier/1, 610 nylon: 500-900 denier/1, polyester:
A combination of two types of thick filaments, such as 400 to 800 denier/1, is often used, and the weave structure includes a flat structure in which the warp and weft threads are intertwined vertically, as well as several threads. There are various transitional weaves that jump and intertwine. In addition, the one that most satisfies the three-dimensional shape reproducibility and appearance characteristics of a molded article with a skin is a nonwoven fabric in which web fibers are entwined by the needle punch method in the absence of a base fabric as described above and reinforced using a binder. It is. In the present invention, since a nonwoven fabric is used as the skin of the molded product with a skin, it is easy to mold into a three-dimensional shape in that it has relatively no directionality in elongation compared to other fiber sheets such as woven or knitted fabrics, and it has a good texture on the surface. ,
It has an excellent texture and is cheaper than woven or knitted fabrics. Raw material fibers include synthetic fibers such as polyester, polypropylene, polyamide, acrylic, vinylon, and polyurethane, semi-synthetic fibers such as acetate and rayon, recycled fibers such as viscose rayon and copper anion rayon, cotton, linen, and sheep. Natural fibers such as silk and blended fibers thereof, and adhesives for forming nonwoven fabrics include acrylic, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, butadiene-styrene copolymer, and polyethylene. , ethylene-acrylic acid copolymer system, ethylene-acrylate copolymer system, ethylene-methacrylic acid copolymer system, ethylene-methacrylate copolymer system, etc. In addition, as for the configuration of the adhesive, it is desirable to laminate it on the nonwoven fabric in a state that does not prevent air permeability in order to prevent air pockets during molding, and when selecting the adhesive in consideration of its compatibility with the blow molding material. It's more effective. The nonwoven fabric used in the present invention has a basis weight of 80~
500Kg/ ^cm2 , preferably 150-350g/ ^m2 ,
Tensile strength (JIS-K-7113) at room temperature (20℃) is 10Kg/cm2 ^or more in both axial directions, preferably 15Kg/ ^cm2
The above are used. If the basis weight is less than 80 g/m ² or the tensile strength at room temperature is less than 10 Kg/cm ² , the plastic base material will be exposed as a foreign material pattern on the surface of the nonwoven fabric in areas where the blow ratio is high, impairing the appearance characteristics. Furthermore, if the basis weight exceeds 500 g/m ² , the three-dimensional shape reproducibility is poor and it is impossible to obtain a molded article with a skin in a desired three-dimensional shape. In addition to the above measures, the elongation of nonwoven fabric at room temperature (JIS
-K-7113) is preferably 30% or more in terms of appearance. Note that the manufacturing method of the present invention is suitable for obtaining a plate-shaped or concave structural member having a hollow double-walled structure in terms of strength and rigidity. In particular, when constructing one or both sides of a structural member, the tensile strength between the mold having the cavity surface configured in the desired three-dimensional shape and the plastic parison is 10 kg/1. A nonwoven fabric of cm ² or more is placed, the parison and the nonwoven fabric are pinched and crimped together at the pinch-off part located at the outer periphery of the cavity of the mold, the parison in the mold is expanded, and the parison and the nonwoven fabric are crimped together. After molding into a three-dimensional shape corresponding to the cavity surface and cooling and solidifying the parison, it is desirable to remove the burr portion of the molded product along the parting line, including the nonwoven fabric. In addition, in the present invention, the basis weight is 80 to 500.
g/m ² non-woven fabric is used,
Even within the above range, if the skin is formed on the entire surface of a structural member, there is a risk of deformation such as sink marks or warping after molding, so the basis weight of the nonwoven fabric should be set to W (g/m ² ), When the molding shrinkage rate of the plastic base material is S (%), S is 0 or more and 3
Deformation can be suppressed by setting W in the following range and W≦-50S+500, and in particular, by setting W≦-140S+500, a further deformation suppressing effect can be obtained. [Function] In the present invention, a specific nonwoven fabric is placed between a mold having a cavity surface configured in a three-dimensional shape and a plastic parison in a plasticized state,
The parison is then expanded. When the parison is inflated, the parison first comes into contact with the adjacent non-woven fabric, and then the inflation pressure of the parison (usually 3-14 kg/
cm ² ), it is pressed against the cavity surface formed in a three-dimensional shape and comes into close contact. At this time, the surface temperature of the parison in a plasticized state is high (for example, 170° C. to 220° C. in the case of polypropylene), and the parison and the nonwoven fabric are thermocompression bonded by the heat and expansion pressure of the parison. It was generally believed that nonwoven fabrics do not have elasticity and cannot be molded into simple shapes by themselves. However, in the present invention, by molding a specific nonwoven fabric under specific conditions, even complex three-dimensional shaped molded products with skins can be manufactured. [Examples] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it departs from the gist thereof. The methods used to measure the physical properties of plastics and nonwoven fabrics in Examples and Comparative Examples are as follows. Melt index (g/10min): JIS-K-7210, 230℃ Density (g/cc): JIS-K-7112 Mold shrinkage rate (%): 24 hours after removing the molded product from the mold It was calculated using the following formula, where L ₁ is the external dimension of the molded product, and L ₂ is the internal dimension of the mold housing corresponding to the length direction of the molded product. L2-L1/L2×100 Fabric weight (g/m ² ): The weight of 10 cm ² was measured with a direct reading balance and converted to the weight per 1 m ² . Tensile strength (Kg/cm ² ) and elongation (%): JIS-K-7113, dumbbell No. 2 test piece, tensile speed 50 mm/min, temperature condition 20°C, thickness measurement micro gauge Thickness (mm): micro gauge Measurement Example 1 An article storage case (hereinafter referred to as a case) is a molded product with a skin and an inner surface made of nonwoven fabric, consisting of a hollow double-walled body, a lid, and a hinge that connects these together. ) manufacturing method will be explained. In FIGS. 1 to 3, numerals 1 and 2 are split-type molds, and numeral 3 is a parison extruded from an extrusion head 4. One of the molds 1 and 2 has convex cavity surfaces 1a and 1b in a three-dimensional shape forming the inner walls of the main body and the lid, and a compression part 1c forming a hinge, Other mold 2
Inside, there are concave cavity surfaces 2a, 2b that face the convex cavity surfaces 1a, 1b and form the inner walls of the main body and lid, and a compressed part 2c that faces the compressed part 1c and forms a hinge. Further, 5 is a nozzle for blowing compressed air into the parison 3, 6 is an exhaust hole for discharging the fluid inside the cavity to the outside, 7 is a nonwoven fabric,
8 is a clamp for holding the nonwoven fabric 7 and placing it in the mold; 9 is a clamp for closing the lower end of the parison 3; 10 is an air outlet for pre-blowing formed in the extrusion head 4; 11 is a metal This is the mold matching surface. As shown in Figure 1, a mixture of 70% by weight polypropylene and 30% by weight talc (melt index 1.02g/10min, density 1.13g/cc,
A split-type mold 1 in which plastic made of plastic (with a molding shrinkage rate of 0.5%) is melt-kneaded in an extruder (not shown) and a cylindrical parison 3 in a molten plasticized state is spaced apart from an extrusion head 4. After being extruded between 2 and 3, the lower end of the parison 3 is closed with a clamp 9 to form a bottomed shape. Moreover, between the convex cavity surfaces 1a and 1b formed in the three-dimensional shape of the molds 1 and 2 and the parison 3, there is a polyester nonwoven fabric (fabric weight 244 g/m ² , elongation at room temperature direction 123
%, Y direction 127%, tensile strength X direction 46Kg/cm ² , Y
direction 86Kg/cm ² ). Then, as shown in FIG. 2, air is blown into the bottomed parison 3 from the air outlet 10 to perform pre-blowing, and the parison 3 and nonwoven fabric 7 are sandwiched over the entire circumference of the mold mating surface 11. As the molds 1 and 2 are closed, the parison 3 first comes into contact with the adjacent nonwoven fabric 7, and then the parison 3 and the nonwoven fabric 7 come into contact with areas of the cavity surfaces 1a, 1b, 2a, and 2c where the blowing ratio is not high. do. Then, as shown in FIGS. 3 and 4, both molds 1 and 2 are closed so that the parison 3 and the nonwoven fabric 7 are sandwiched and thermocompressed together over the front peripheral surface of the mold mating surface 11, and the parison At the same time, compressed air (5.3Kg/cm ² ) is blown into the cavity surface 1 from the exhaust hole 6 of the molds 1 and 2 through the nozzle 5.
The air between a, 1b and the parison 3 is forcibly discharged to the outside. In this way, the parison 3 slides on the surfaces of the cavities 1a and 1b with the nonwoven fabric in contact with each other, expands to the corners of the cavity surfaces 1a and 1b where the blowing ratio is high, and is formed into a shape corresponding to the cavity surfaces 1a and 1b. The nonwoven fabric 7 and the nonwoven fabric 7 are thermocompression bonded by the heat and expansion pressure of the parison 3 and take on a three-dimensional shape. At the same time, the parison 3 and the nonwoven fabric 7 are compressed by the compression parts 1c and 2c that protrude oppositely into the molds 1 and 2, forming a thin hinge. Then, after cooling and solidifying by maintaining this state for 80 seconds, molds 1 and 2 are
, remove the molded product, remove burrs along the entire parting line where the solidified plastic of the Parison and the nonwoven fabric were sandwiched and crimped, and
A main body 21 having a hollow double wall structure as shown in FIG.
Lid body 22 and hinge 2 that connects these together
3, consisting of a main body 21, a lid body 22, and a hinge 23.
A case 20, which is an example of a molded article with a skin, was obtained in which the skin of the nonwoven fabric 7 was formed over the entire inner surface of the case 20. The external dimensions of the case mating surface of the case 20 are 460 mm in length and 480 mm in width, and the plastic 2 serving as the base material
The average wall thickness of 9 is 1.5 mm, and the average wall thickness of nonwoven fabric 7 is 0.6
It was warm in mm. Observing the manufactured case 20, the mold cavity surface 1
The three-dimensional shape of a was faithfully reproduced, and no exposure of the plastic 29, which was the base material, was observed. Also, there are marks 26 and 27 on the outer peripheral end surface of the case 20, which are the marks left after removing burrs along the entire circumferential surface of the parting line where the plastic and nonwoven fabric were sandwiched and crimped.
Also, the nonwoven fabric did not come undone and was well bonded. Furthermore, after molding the case 20 and leaving it for 24 hours, no deformation such as sink marks or warping due to the adhesion of the nonwoven fabric was observed. Examples 2 to 10 and Comparative Examples 1 to 7 Using a mold in which the cavity surface on the side in contact with the nonwoven fabric was set to dimensions as shown in FIG. 6, with a mold apparatus as shown in FIG. A hollow double-walled concave container (hereinafter referred to as a container), which is a molded article with a skin as shown in FIG. 8, was obtained. In addition, the seventh
In the figure, 31 and 32 are molds, 31a is a concave cavity surface, 32a is a convex cavity surface, 33 is a parison, 35 is a nozzle, 36 is an exhaust hole, and 37 is a nonwoven fabric. Further, in FIG. 8, 40 is a container, and 46 is an end face of a trace where burrs have been removed. The manufacturing method was the same as in Example 1 except that the hinge forming step was not included. The plastic 49 used was the same as in Example 1, and the nonwoven fabric shown in Table 1 was used. Moreover, the molding conditions are as follows. Extrusion temperature: 200℃ Blow pressure: 4Kg/cm ² Extrusion dance: 90mm diameter circular die Cooling cycle in the mold: 60 seconds

【table】

[Table] The results of evaluating the skinned molded products of Examples 2 to 10 and Comparative Examples 1 to 7 thus obtained in terms of three-dimensional shape reproducibility, exposure of the base material, and aesthetic appearance of the end surface are shown in the second table. Shown in the table. Three-dimensional shape reproducibility: The radius of curvature of the corner part A2 of the molded product with skin shown in Fig. 8, which was molded at the corner part A1 of the cavity surface shown in Figs. 6 and 7 with a radius of curvature of 0.5 mm, was measured. , "○" means that the radius of curvature is molded from 0.5 mm to less than 1.0 mm, "△" means that the radius of curvature is molded from 1.0 mm to less than 1.5 mm, and "×" means that the radius of curvature is molded from 1.5 mm to less than 1.5 mm. ”. Exposure of the base material: The corner part B2 of the molded product with skin shown in FIG. 8, which was molded at the corner part B1 of the cavity surface shown in FIGS. 6 and 7, was observed with the naked eye, and the plastic 49 that is the base material was observed. ``○'' indicates that the surface of the nonwoven fabric is not exposed at all, and ``△'' indicates that it is slightly exposed.
When the plastic base material is completely exposed, it is marked as "x". Aesthetics of end face: Observe the end face 46 shown in FIG. 8 where burrs have been removed along the parting line where the plastic and non-woven fabric are sandwiched and crimped. If there is no unraveling of the non-woven fabric, it is marked "○", but it is not noticeable. Those with slight unraveling are indicated as "△", and those with severe unraveling are indicated as "x".

【table】

[Table] As shown in Table 2, the basis weight is 80 to 500g/
The skinned molded products of Examples ² to 10, which used non-woven fabrics with a size of 10 kg/cm ² and a tensile strength of 10 Kg/cm 2 or more, almost faithfully reproduced the shape of the cavity surface of the mold, and also showed good performance even in areas with a high blow ratio. The appearance characteristics were not impaired. In contrast, Comparative Examples 1 and 2 using nonwoven fabrics with a basis weight of less than 80 g/ ^m2 , and
Comparative example 7 using nonwoven fabric exceeding 500g/ ^m2 ,
Furthermore, in Comparative Example 4, which used a nonwoven fabric with a tensile strength of less than 10 Kg/cm ² in both axial directions, neither the reproducibility nor the appearance were satisfied. In particular, Table 2 shows that Examples 3 to 8 in which nonwoven fabrics with a basis weight of 150 to 350 g/m ² were used were excellent in both three-dimensional shape reproducibility and appearance characteristics. Examples 11 to 19 and Comparative Examples 8 to 11 A hollow double-wall structure board (set size: 1000 mm vertically) which is a molded product with a skin as shown in FIG. , width 350mm, height 20
mm, the average wall thickness of the base material was 2.5 mm, the weight of the molded product was 2500 g, and the cooling cycle in the mold was 180 seconds). In FIG. 9, 51 and 52 are molds, 51a and 52a are cavity surfaces, 53 is a parison, 55 is a nozzle, 56 is an exhaust hole, and 57 is a nonwoven fabric. Further, in FIG. 10, 60 is a board manufactured using the molding machine shown in FIG. 9, 61 is a hollow rib, 66 is an end surface where burrs are removed, and 69 is plastic. The manufacturing method was the same as in Example 1 except that the hinge molding step was not included. In addition, 13 types of boards were obtained using the plastic base materials shown in Table 3, the non-woven fabrics shown in Table 1, and the combinations shown in Table 4. The thus obtained boards of Examples 11 to 19 and Comparative Examples 8 to 11 were evaluated in terms of deformation resistance and base material exposure. The results are shown in Table 4 and used in the Examples and Comparative Examples. FIG. 12 shows the relationship between the molding shrinkage rate of the base material and the basis weight of the nonwoven fabric. In addition, the 12th
In the figure, "_" indicates the number of the example, and "()" indicates the number of the comparative example.

[Table] Deformation resistance (mm): 24 hours after the molded board 60 was taken out of the mold, the virtual straight line L connecting both ends of the outer surface in the vertical direction as shown in FIG. The length H measured up to the outer surface of the most concavely deformed part was measured. Exposure of base material: The corners of the hollow ribs 61 of the molded board 60 were observed with the naked eye, and the evaluation criteria for ○, Δ, and × were the same as in Table 2.

〔Effect of the invention〕

The method for manufacturing a molded article with a skin according to the present invention can easily manufacture even a molded article having a complex three-dimensional shape with excellent three-dimensional shape reproducibility, and the plastic base material can be easily manufactured by forming a plastic base material into a non-woven fabric with fine gaps. It is possible to produce a skin molded product with excellent appearance characteristics without exposing a foreign material pattern on the surface of the nonwoven fabric. The present invention is suitable as a method for manufacturing a molded article with laminated skins for decoration, heat insulation, or reinforcement.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the case manufacturing method according to the present invention, in which FIG. 1 is a side view when the mold is opened, FIG. 2 is a side sectional view immediately before the mold is closed, Fig. 3 is a side sectional view when the mold is closed, Fig. 4 is a sectional view taken along line A-A' in Fig. 3, Fig. 5 is a sectional perspective view of the manufactured case, and Figs. 6 is an explanatory diagram illustrating the set dimensions of the cavity surface on the side in contact with the nonwoven fabric, FIG. 7 is a side sectional view when the mold is closed, and FIG. 8 is a cross-sectional perspective view of the manufactured container, and FIGS. 9 to 10 show an embodiment of the board manufacturing method according to the present invention. FIG. 9 is a side sectional view when the mold is closed, and FIG. Figure 10 is a cross-sectional perspective view of the manufactured board, Figure 11 is an explanatory diagram explaining the method for measuring the amount of deformation, Figure 12 is a diagram showing the relationship between the molding shrinkage rate of the base material and the basis weight of the nonwoven fabric. FIG. 13 is an explanatory diagram illustrating problems with conventional skinned molded products, and FIG. 14 is an explanatory diagram illustrating a manufacturing method of needle punched cloth. 1, 2: Mold, 1a, 1b: Convex cavity surface, 2a, 2b: Concave cavity surface, 3: Parison, 7: Nonwoven fabric, 20: Case, 31, 32: Mold, 31a: Concave cavity surface , 32a: Convex cavity surface, 33: Parison, 37: Nonwoven fabric, 4
0: Container, 51, 52: Mold, 51a, 52
a: cavity surface, 53: parison, 57: nonwoven fabric, 60: board.

Claims (1)

[Claims] 1. The basis weight is between 80 and 500 g between the mold having a cavity surface formed into a desired three-dimensional shape and the thermoplastic plastic parisson in a plasticized state.
A non-woven fabric with a tensile strength of 10 Kg/cm ² or ^more is placed, and then the parison is expanded and the non-woven fabric is thermo-bonded with the parison and molded into a three-dimensional shape along the cavity surface of the mold, and this state is maintained. A method for producing a molded product with a skin, characterized in that the molded product is produced by cooling and solidifying the product.