JP2021130246A - Method of producing molded product - Google Patents

Abstract

To provide a method of producing a molded product capable of increasing production efficiency.SOLUTION: A method of producing a molded product is a method of forming a molded product 10 by molding a base material 11 made of a fiber board 11A including vegetable fibers and thermoplastic resin and includes: a setting step of setting the heated and softened base material in a lower die 21 of a cold press device 20; and a pressing step of cold pressing the base material by mold closing the cold press device. The lower die is formed of a material having heat conductivity smaller than that of stainless steel.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a molded product by molding a base material made of a fiber board containing a plant fiber and a thermoplastic resin to produce a molded product.

As a molded product whose use is used as a vehicle interior material, for example, a fiber board in which plant fibers are bound with a thermoplastic resin is used. This molded product is manufactured by cold-pressing a heat-softened base material to form an arbitrary shape. As for the method for producing such a molded product, the technique described in Patent Document 1 and the like are known. In the manufacturing method described in Patent Document 1 and the like, as shown in FIG. 4A, after placing the heat-softened base material on the upper surface of the lower mold of the cold press at room temperature, FIG. 4 (a) As shown in b), a molded product is obtained by lowering the upper mold and pressing the base material. In the molded product shown in FIG. 4, a skin material is attached to one surface of the base material, and the skin material is set in the upper mold during cold pressing and pressed integrally with the base material.

JP-A-2019-155977

However, in the molded product produced by the above method, the lower surface of the base material starts to be cooled by the lower mold from the time when the heat-softened base material is set in the lower mold of the cold press machine. A large temperature difference occurs between the upper surface and the lower surface of the material. Along with this, there is a difference in the shrinkage rate between the upper surface portion and the lower surface portion of the base material, so that the base material is deformed due to warpage. In particular, when the thermoplastic resin contained in the base material is made of a crystalline resin such as a polyolefin resin, the deformation due to the difference in shrinkage is large.
The molded product deformed in this way requires a work of straightening by pressing from both sides using a jig or the like in a subsequent process, which causes a decrease in production efficiency.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a molded product capable of improving production efficiency.

In order to solve the above problems, the present invention is shown below.
The invention according to claim 1 is a method for producing a molded product by molding a base material made of a fiber board containing a plant fiber and a thermoplastic resin to form a molded product, wherein the heat-softened base material is used. The lower mold includes a setting process of setting the lower mold of the cold press machine and a pressing process of molding the cold press machine and cold pressing the base material, and the lower mold has a heat conductivity smaller than that of stainless steel. The gist is that it was made of a material with a ratio.
The gist of the invention according to claim 2 is that, in the invention according to claim 1, the lower mold is made of a material having a thermal conductivity smaller than that of stainless steel as a whole.
The invention according to claim 3 is the invention according to claim 1, wherein the lower mold is made of a material having a thermal conductivity smaller than that of stainless steel at the surface layer portion with which the base material to be set abuts. Is the gist.
The gist of the invention according to claim 4 is that the lower mold is made of a resin in the invention according to any one of claims 1 to 3.
The gist of the invention according to claim 5 is that the thermoplastic resin is made of a crystalline resin in the invention according to any one of claims 1 to 4.
The gist of the invention according to claim 6 is that the molded product is a package tray in the invention according to any one of claims 1 to 5.

According to the present invention, in a method for producing a molded body for molding a base material made of a fiber board containing a plant fiber and a thermoplastic resin, by suppressing bending deformation due to a difference in heat shrinkage of the base material during cold pressing, It is possible to improve the production efficiency by eliminating the work of correcting the deformed molded body by using a jig or the like in the subsequent process.

The present invention will be further described in the following detailed description with reference to the plurality of references mentioned with reference to non-limiting examples of typical embodiments according to the invention. Similar parts are shown through several figures.
It is a process drawing explaining the manufacturing method of the molded article of this embodiment. It is a schematic diagram which shows the upper die and the lower die of the cold press machine used in the forming press process of FIG. 1, (a) shows the state at the time of setting, (b) shows the state at the time of a press. It is explanatory drawing explaining the method of measuring the deformation amount of the sample of an Example and a comparative example. It is a schematic diagram which shows the upper mold and the lower mold of the cold press machine used in the molding press process in the conventional molding manufacturing method, (a) shows the state at the time of setting, (b) shows the state at the time of a press. .. It is explanatory drawing explaining the deformed state of the base material which occurs in the manufacturing method of the conventional molded article. It is explanatory drawing explaining the straightening method in the manufacturing method of the conventional molded article.

The matters shown here are for exemplifying and exemplifying embodiments of the present invention, and are considered to be the most effective and effortless explanations for understanding the principles and conceptual features of the present invention. It is stated for the purpose of providing what seems to be. In this regard, it is not intended to show structural details of the invention beyond a certain degree necessary for a fundamental understanding of the invention, and some embodiments of the invention are provided by description in conjunction with the drawings. It is intended to clarify to those skilled in the art how it is actually realized.

The method for producing a molded product of the present embodiment is a method for producing a molded product by molding a base material made of a fiber board containing plant fibers and a thermoplastic resin, and as shown in FIG. 1, it is heat-softened. After the base material 11 is placed on the upper surface of the lower mold 21 of the cold press machine 20 and set, the lower mold 21 and the upper mold 22 are mold-clamped and cold-pressed to produce a molded product.
Here, in particular, the lower mold 21 of the cold press machine 20 used in the present embodiment may have a thermal conductivity smaller than that of stainless steel at least in the surface layer portion 21b with which the base material 11 to be set is in contact. It is made of the material that it has.

The molded body is not limited in shape, size, thickness, etc., and is not limited in use, but examples of the molded body include interior materials and exterior materials of automobiles, railroad vehicles, ships, airplanes, and the like.
Of these, as interior and exterior materials for automobiles, specifically, package trays, door base materials, pillar garnishes, switch bases, quarter panels, side panels, armrests, automobile door trims, seat structural materials, seat backboards, ceilings. Materials, console boxes, automotive dashboards, various instrument panels, deck trims, bumpers, spoilers, cowlings, etc.
This molded product is particularly useful as an interior material for automobiles because it is lightweight and has high rigidity.

In addition to the above-mentioned molded products, examples thereof include interior materials and exterior materials for buildings, furniture, and the like.
That is, door covering materials, door structural materials, desks, chairs, shelves, covering materials for various furniture such as chests of drawers, and the like can be mentioned. In addition, a packaging body, an accommodating body such as a tray, a protective member, a partition member, and the like can be mentioned.

Among the above-mentioned interior materials for automobiles, the package tray is a large plate-like material having a size of, for example, 1,500 × 1,300 mm or 1,300 × 700 mm, and is easily deformed. It is particularly suitable as a molded product because it requires straightening work.

In this embodiment, a package tray 10 having a base material 11 and a skin material 12 attached to one surface of the base material 11 is exemplified as a molded body. The skin material 12 is set on the upper mold 22 side during cold pressing.
However, although not illustrated, the molded product may be composed of only the base material 11 without including the skin material 12.

Hereinafter, each constituent member will be specifically shown. The fiber board 11A constituting the base material 11 has a plate shape of a predetermined thickness and contains plant fibers and a thermoplastic resin. Of these, plant fibers are fibers extracted from plants (trunks, stems, branches, leaves, roots, etc.) and include leaf vein-based plant fibers, bast-based plant fibers, wood-based plant fibers, and the like.
The plant body that is the source of plant fiber is not limited, for example, kenaf, hemp, jute hemp, ramie, flax, Manila hemp, sisal hemp, ganpi, sansho, 楮, banana, pineapple, coconut palm, corn, sugar cane, etc. Examples include bagasse, palm, papyrus, reeds, esparto, survivorgrass, wheat, rice, bamboo, various conifers (sugi and hinoki, etc.), broadleaf trees and cotton. As these plants, only one kind may be used, or two or more kinds may be used in combination.
Among the above-mentioned plants, kenaf, hemp, jute hemp, ramie, and flax (flux) are preferable as the plant body which is the source of the plant fiber, and kenaf is particularly preferable, and further, kenaf is preferable. Kenaf fibers collected from the kenaf bast are particularly preferred.

The specific shape of the plant fiber is not limited, but for example, the average fiber length can be 10 to 200 mm (further 20 to 170 mm, particularly 25 to 150 mm, especially 30 to 90 mm). This average fiber length is based on JIS L1015, and single fibers are randomly taken out one by one by the direct method, straightened without stretching, and the fiber length is measured on a scale, for a total of 200 fibers. It is the average value of the measured values.
The fiber diameter of the plant fiber is also not limited, but for example, the average fiber diameter can be 1 to 2500 μm (further 10 to 2000 μm, particularly 100 to 1750 μm, particularly 200 to 1500 μm). This average fiber diameter is an average value of values measured using an optical microscope at the center of each of the 200 single fibers used for measuring the average fiber length in the length direction.

The fiber board 11A constituting the base material 11 contains a thermoplastic resin as a binder resin for binding plant fibers to each other. The type of this thermoplastic resin is not limited, and well-known ones can be used.
The thermoplastic resin is mainly a crystalline resin having a large molding shrinkage rate. The crystalline resin has a crystalline portion in which molecules are regularly arranged when the temperature of the molten resin drops to the crystallization temperature and solidifies.
Specific examples of the crystalline resin include thermoplastic resins such as polyolefin resins, polyester resins, polyamide resins, fluororesins, polyacetal resins, polyphenylene sulfide resins, and polyether ether ketone resins. Only one of these may be used, or two or more thereof may be used in combination.
However, the thermoplastic resin is not limited to the crystalline resin, but also includes an amorphous resin having a small molding shrinkage rate. Specific examples of the amorphous resin include polyvinyl chloride, polystyrene, polymethylmethacrylate, ABS (acrylonitrile-butadiene-styrene), and polycarbonate.

Examples of the above-mentioned polyester resin include polylactic acid, aliphatic polyester resin, aromatic polyester resin and the like. Examples of the aliphatic polyester resin include polycaprolactone and polybutylene succinate. Examples of the aromatic polyester resin include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.
Examples of the above-mentioned fluororesin include polytetrafluoroethylene and ethylene / tetrafluoroethylene copolymers.

Among the above-mentioned, as the thermoplastic resin, a polyolefin resin is preferable.
Examples of the olefin monomer constituting the polyolefin resin include ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene and 1-. Examples include hexene and 1-octene. Only one of these may be used, or two or more thereof may be used in combination.
That is, examples of the polyolefin resin include polyethylene resins such as an ethylene homopolymer, an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, and an ethylene / 4-methyl-1-pentene copolymer. ..
These polyethylene resins are resin in which 50% or more of the total number of constituent units is derived from ethylene. Further, polypropylene resins such as a propylene homopolymer, a propylene / ethylene copolymer (propylene / ethylene random copolymer, etc.), and a propylene / 1-butene copolymer can be mentioned. These polypropylene resins are resin in which 50% or more of the total number of constituent units is derived from propylene.

The fiber board 11A constituting the base material 11 may be composed of only plant fibers and thermoplastic resin fibers, but if necessary, a plasticizer (plasticizer for binder resin), an antioxidant, a flame retardant, and the like. It can contain other components such as lubricants, antifungal agents, antibacterial agents, fillers and colorants.
When the fiber board 11A contains other components, the content of the other components is usually 0.1 to 10 parts by mass when the total mass of the plant fiber and the thermoplastic resin fiber is 100 parts by mass.

The ratio between the total amount of plant fibers contained in the fiber board 11A and the total amount of thermoplastic resin fibers is not limited, but when the total amount of plant fibers and the total amount of thermoplastic resin fibers is 100% by mass, the plant The ratio of the total amount of fibers can be 10 to 90% by mass, preferably 15 to 85% by mass, more preferably 20 to 80% by mass, still more preferably 25 to 75% by mass, and 30 to 70% by mass. Is particularly preferable, 35 to 65% by mass is particularly preferable, and 40 to 60% by mass is particularly preferable.

The thickness of the fiber board 11A is not particularly limited and may be an appropriate thickness depending on the intended use of the molded product, etc., but is usually 0.5 to 200 mm, particularly 0.5 to 80 mm. When the thickness of the fiber board is 0.5 to 200 mm, it can be used as a lightweight member having sufficient strength in many applications. In the present embodiment, the thickness of the fiber board 11A is 2.5 to 3.5 mm.

The basis weight of the fiber board 11A is not particularly limited, and can be, for example, 200 to 3000 g / m ² . The basis weight is more preferably a 400~2500g / ^{m 2,} further preferably a 600~2000g / ^{m 2,} it is preferable that further 800~1800g / ^{m 2.}

The skin material 12 is a sheet-like member to be attached to one surface of the base material 11, and is not particularly limited as long as it can be attached to the base material 11. For example, a non-woven fabric, a woven fabric, a knitted cloth, or the like. Leather such as synthetic leather and genuine leather, resin film, wood grain sheet and the like can be used. Among these, non-woven fabric is preferable.

The non-woven fabric is made into a sheet by entwining fibers.
The method of entwining the fibers is not particularly limited, and examples thereof include a needle punch method, a stitch bond method, a spun bond method, a chemical bond method, a thermal bond method, a melt blow method, a spunlace method, a steam jet method, and a water punch method. Can be mentioned.

The fibers used for the non-woven fabric are not particularly limited, and for example, resin fibers made of the above-mentioned thermoplastic resin, inorganic fibers such as glass fibers, natural fibers such as the above-mentioned plant fibers, cotton and cellulose fibers, and half of rayon fibers and the like. Synthetic fibers and the like can be mentioned. Only one of these may be used, or two or more thereof may be used in combination. Among these, resin fibers are preferable.

As for the non-woven fabric (skin material 12), similarly to the fiber board 11A, a plasticizer (plasticizer for resin fibers), an antioxidant, a flame retardant, a lubricant, a fungicide, an antibacterial agent, a filler, etc. Other components such as colorants can be included.

As shown in FIGS. 1 and 2, the cold press machine 20 of the present embodiment cold presses the base material 11 and the skin material 12 integrally on the fixed lower mold 21 and the lower mold 21. On the other hand, it is provided with an upper mold 22 that can move in the vertical direction. The lower mold 21 and the upper mold 22 are formed into molded bodies having a predetermined shape by pressing the base material 11 and the skin material 12 between the mold surfaces of each other. The cold press 20 is not limited to the above configuration, and the upper mold 22 may be fixed or movable, and the lower mold 21 may be movable.

The material of the lower mold 21 is a material having a low thermal conductivity as a whole in order to prevent the base material 11 from being rapidly cooled when the base material 11 which has been heated and melted is placed and comes into surface contact with the lower mold 21. The lower mold 21 is made of a steel material generally used as a material, particularly a material having a thermal conductivity smaller than that of stainless steel.

The material of the lower mold 21 includes resin materials such as epoxy resin, polyethylene resin, phenol resin, silicon, and urethane foam, as well as alumina, ittoria, zirconia, zircon, cozy light, brick, marble, granite, sand rock, pebble, and crystal. , Calcium silicate, inorganic substances such as concrete, wood, glass and the like. In this embodiment, epoxy resin is used as the material of the lower mold 21.

Here, the lower mold 21 may be the whole as described above, but only the surface layer portion 21b, which is the peripheral portion of the contact surface 21a on which the base material 11 to be set is placed and abuttes, has a thermal conductivity smaller than that of stainless steel. It may be formed of a material having a conductivity. In this case, the lower mold 21 may be formed of a steel material such as stainless steel, and the surface portion 21b may be coated or bonded with a resin material such as an epoxy resin or a phenol resin. Further, in the lower mold 21, the surface layer portion 21b is formed of a resin material such as epoxy resin, and the other portion is formed of a steel material such as stainless steel, and these are assembled and joined to form a laminated structure. It can also be.

On the other hand, the material of the upper mold 22 is not particularly limited, and the material generally used in the cold press machine 20 can be used, for example, a metal material such as stainless steel, iron, aluminum, copper, and brass. Can be used.

As shown in FIGS. 1 and 2A, the setting step of the present embodiment is a step of setting the heat-softened base material 11 on the lower mold 21 of the cold press machine 20.
Further, as shown in FIG. 2B, the pressing step of the present embodiment is a step of cold-pressing the lower die 21 and the upper die 22 by molding.

Next, in the method for producing a molded product of the present embodiment, a method for producing a package tray 10 which is a molded product by molding a base material 11 made of a fiber board 11A containing plant fibers and a thermoplastic resin is shown in FIG. This will be described with reference to FIG.
First, in the base material heating step 30 of FIG. 1, the base material 11 made of the fiber board 11A is heated and softened by the heating device 40. The heating temperature at which the base material 11 is heated and softened is a temperature 10 ° C. higher than the melting point of the thermoplastic resin. In the present embodiment, when the polyolefin resin is used as the thermoplastic resin, the melting point of the polyolefin resin is 170 ° C., so the heating temperature of the base material 11 is set to 180 ° C.

Next, the base material 11 heated and softened in the base material heating step 30 is transferred to the next molding press step 31 and cooled at room temperature in the first setting step, as shown in FIG. 2 (a). It is placed on the mounting surface of the lower mold 21 of the inter-press machine 20. In this step, at the same time, the skin material 12 at room temperature is also set in the upper mold 22 of the cold press machine 20. Next, in the pressing step in the forming pressing step 31, as shown in FIG. 2B, the upper die 22 is lowered and the die is compacted to integrally press the base material 11 and the skin material 12. At this time, the lowering time of the upper mold 22 is about 15 seconds. The heat-softened base material 11 is cooled at a predetermined cooling temperature by a cold press and formed into a predetermined shape. Further, when the skin material 12 is pressed against one surface of the heat-softened base material 11, the molten thermoplastic resin permeates the surface material 11 so that the skin material 12 is attached to one surface of the base material 11.

The press pressure in the press step in the molding press step 31 is not particularly limited, but is preferable from the viewpoint of handleability of the base material 11 and the skin material 12 and facilitation of suitable processing (molding) on the molded product. It is 0.2 to 0.8 MPa, more preferably 0.25 to 0.7 MPa, and particularly preferably 0.3 to 0.6 MPa.
The cooling temperature in the pressing step is preferably 100 to 150 ° C., more preferably 110, than the melting point of one type of thermoplastic resin contained in the base material 11 and the lowest melting point of two or more types of thermoplastic resin. It is a temperature as low as ~ 140 ° C., particularly preferably 115 to 135 ° C.

By this pressing step, the base material 11 formed into a predetermined shape and the skin material 12 attached to one surface thereof are subjected to processing such as cutting and drilling of edges in the next trimming step 32, whereby molding is performed. The body package tray 10 is completed.

Next, the operation of the method for producing a molded product of the present embodiment will be described.
Conventionally, in the forming press process, as shown in FIG. 4, the lower die 21 and the upper die 22 of the cold press machine 20 are generally formed of a metal having a high thermal conductivity such as stainless steel or nickel-chromium steel. rice field. Therefore, the base material 11 is placed on the lower mold 21 in the setting process, and from the time when it comes into direct contact with the lower mold 21, heat is taken away by the lower mold 21 at room temperature, and the lower surface 11b, which is the contact surface, is cooled quickly. In this way, when rapidly cooled, crystallization does not proceed sufficiently due to the characteristics of the thermoplastic resin (for example, polyolefin resin, etc.), so that the amount of shrinkage on the lower surface 11b side is small as shown in FIG. 5A. .. On the other hand, the upper surface 11a side of the base material 11 is not in direct contact with the lower mold 21 and the upper mold 22 at the time when the base material 11 is set, so that it is gradually cooled to crystallize the thermoplastic resin. As the crystallization progresses, the amount of shrinkage is larger than that on the lower surface 11b side. As a result, a large temperature difference is generated between the upper surface 11a and the lower surface 11b of the base material 11 immediately after the start of mold clamping, whereby the upper surface 11a side and the lower surface 11b side of the base material 11 are separated from each other. Since there is a difference in shrinkage rate, the base material 11 after molding is deformed due to a large bending warp as shown in FIG. 5 (b).

As a result, conventionally, as shown in FIG. 6, the molded body deformed in this way has been corrected by pressing it with an air cylinder from both sides using a jig or the like as shown in FIG. This has led to a decrease in production efficiency.

On the other hand, according to the method for producing a molded product of the present embodiment, in the lower mold 21 of the cold press machine 20, at least the surface layer portion 21b with which the base material 11 abuts has a thermal conductivity smaller than that of stainless steel as described above. It is made of an epoxy resin having. The thermal conductivity of epoxy resin is about two orders of magnitude smaller than that of stainless steel, as will be described later. Therefore, in the molding press step 31, when the heat-softened base material 11 is placed on the lower mold 21 and comes into direct contact with the surface thereof, the base material 11 has a heat insulating effect due to the material of the lower mold 21 having a small thermal conductivity. As a result, the lower surface 11b is rapidly cooled and the temperature is suppressed from dropping. As a result, the temperature difference between the upper surface 11a side and the lower surface 11b side of the base material 11 becomes smaller, and the difference in the amount of resin shrinkage becomes smaller. It is suppressed. As a result, it is possible to omit the work of straightening the package tray 10 which is a deformed molded body with a jig or the like in a subsequent process, so that the production efficiency can be improved.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

[Material used]
[Base material]
As the base material 11, a fiber board 11A containing plant fibers and a thermoplastic resin for binding the plant fibers was used.
Kenaf fiber was used as the plant fiber. This kenaf fiber was obtained by defibrating the bast taken out from the kenaf, and the average fiber length was 70 mm.
As the thermoplastic resin fiber, a resin fiber having a melting point of 170 ° C. and a fineness of 6.6 dtex, which was obtained by melt-spinning a polypropylene resin, was used. The resin fibers were cut to have an average fiber length of 50 mm.
50 parts by mass of the kenaf fiber and 50 parts by mass of the resin fiber are mixed, the mixed cotton is laminated by the air array method, entangled by the needle punch method, and then heated at a temperature of 200 ° C. and a pressing time of 120 seconds. The fiber board 11A was obtained by cooling at a temperature of 30 ° C. and a pressing time of 180 seconds. The obtained fiber board 11A had a basis weight of 1500 g / m ² and a thickness of 2.3 mm.

[Skin material]
As the skin material 12, a non-woven fabric obtained by entwining resin fibers by a needle punching method was used.
As the resin fiber, one having a melting point of 260 ° C. and a fineness of 3.3 dtex obtained by melt-spinning a polyethylene terephthalate resin was used.
The non-woven fabric had a basis weight of 180 g / m ² and a thickness of 1.0 mm.

〔Example〕
[Cold press]
The upper mold 22 was entirely made of stainless steel. The temperature of the upper mold 22 is 28 ° C. Here, the thermal conductivity of stainless steel is 16.7 to 20.9 W / m · K.
The lower mold 21 was entirely made of epoxy resin. The temperature of the lower mold 21 is 28 ° C. Here, the thermal conductivity of the epoxy resin is 0.21 W / m · K.
[Set process]
The base material 11 softened by heating at 170 ° C. in advance was directly placed on the lower mold 21 of the cold press machine 20. The skin material 12 was attached to the upper mold 22 of the cold press machine 20.
[Press process]
The upper mold 22 of the cold press 20 was lowered in 15 seconds, and the lower mold 21 and the upper mold 22 were molded. The press pressure was 0.5 MPa for cold pressing, and No. Sample 10A of 1 was obtained.
The obtained No. Sample 10A of 1 had a square shape with a side length of 30 cm and a thickness of 2.5 mm.

[Comparative example]
[Cold press]
The upper mold 22 was entirely made of stainless steel.
The lower mold 21 was also made entirely of stainless steel.
[Set process]
The base material 11 and the skin material 12 were set in the same manner as in Examples.
[Press process]
Cold press in the same manner as in the above embodiment, and No. Sample 10A of 2 was obtained.
The obtained No. Sample 10A of No. 2 had a square shape with a side length of 30 cm and a thickness of 2.5 mm.

〔evaluation〕
Immediately before the pressing process, No. For the base material 11 used in each of the samples 1 and 2, the temperatures of the upper surface 11a and the lower surface 11b were measured, and the temperature difference between them was calculated. The results are shown in Table 1.
After the pressing process, No. The amount of deformation was measured for each of the samples 1 and 2 10A. As shown in FIG. 3, the amount of deformation was measured by pressing one side edge of the sample 10A against the mounting surface G and bringing it into contact with the other side edge to be lifted from the mounting surface G. The distance W from the end point H of the base material 11 to the mounting surface G was measured at the other side edge portion. Further, the distance W was measured at each sample 10A at a total of eight end points H at the center of each side and each corner, and the one having the largest numerical value was defined as the amount of deformation. The results are shown in Table 1.

From Table 1, the following is clear.
In the sample 10A of the example, the temperature difference between the upper surface 11a and the lower surface 11b of the base material 11 was 10 ° C., and the amount of deformation was 1 mm.
In the sample 10A of the comparative example, the temperature difference between the upper surface 11a and the lower surface 11b was 75 ° C., and the amount of deformation was 6 mm.
From the above, the lower mold 21 of the cold press 20 is made of an epoxy resin having a low thermal conductivity, which causes a temperature difference between the upper surface 11a and the lower surface 11b of the base material 11 due to the heat insulating effect. It is clear that the deformation of the base material 11 due to the difference in cooling between the upper surface 11a and the lower surface 11b is suppressed.

In the in-house standard, the allowable deformation amount of the package tray 10, which is a molded product molded by the manufacturing method of the present embodiment, is set to 3 mm, and the deformation amount of the comparative example is a standard value after cold pressing. However, the amount of deformation of the embodiment is within the standard value.

The above examples are for illustration purposes only and are not to be construed as limiting the invention. Although the present invention has been described with reference to typical embodiments, the language used in the description and illustration of the invention is understood to be descriptive and exemplary rather than restrictive. .. As described in detail here, modifications can be made within the scope of the appended claims without departing from the scope or spirit of the invention in that form. Although specific structures, materials and examples have been referred to herein in detail of the invention, it is not intended to limit the invention to the disclosures herein, but rather the invention is claimed in the accompanying claims. It shall cover all functionally equivalent structures, methods and uses within the scope of.

The present invention can be used in a wide range of product fields such as vehicles and building materials, and is particularly useful as a method for manufacturing vehicle interior materials, and is preferably used for various interior materials such as package trays.

10; Package tray, 11; Base material, 11A; Fiber board, 12; Skin material, 20; Cold press, 21; Lower mold, 21b; Surface layer.

Claims (6)

A method for producing a molded product by molding a base material made of a fiber board containing plant fibers and a thermoplastic resin to form a molded product.
The setting process of setting the heat-softened base material in the lower mold of the cold press, and
A press step of cold-pressing the base material by molding the cold press machine is provided.
The lower mold is a method for manufacturing a molded product, characterized in that the lower mold is made of a material having a thermal conductivity smaller than that of stainless steel. The method for producing a molded product according to claim 1, wherein the lower mold is made of a material having a thermal conductivity smaller than that of stainless steel as a whole. The method for producing a molded product according to claim 1, wherein the lower mold is formed of a material having a thermal conductivity lower than that of stainless steel in a surface layer portion with which the base material to be set abuts. The method for producing a molded product according to any one of claims 1 to 3, wherein the lower mold is made of a resin. The method for producing a molded product according to any one of claims 1 to 4, wherein the thermoplastic resin is made of a crystalline resin. The method for producing a molded product according to any one of claims 1 to 5, wherein the molded product is a package tray.

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