JPH09183163A - Preparation of polyolefin resin structural body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare efficiently and favorably in cost a polyolefin resin structural body consisting of a base body made of a polyolefin resin and a surface sheet made of a polyolefin resin. SOLUTION: This method for preparing a polyolefin resin structural body wherein a base body made of a polyolefin resin and a surface sheet made of a polyolefin resin on one face of which unevenness based on embossing is provided are integrally laminated is provided and the method includes a process wherein after a molten polyolefin resin is calendered into a sheet and unevenness is provided on one face by embossing, the sheet is cut and molded preliminarily and it is mounted in a mold for injection molding in such a way that the opposite face to the uneven face of the sheet is brought into contact with a resin being filled by injection and a molten polyolefin resin for the base body is injected and filled into the cavity of the mold to mold integrally the sheet and the base body.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyolefin-based resin structure having excellent recyclability, appearance, functionality and the like.

[0002]

2. Description of the Related Art In recent years, resource problems and environmental problems have been discussed on a global scale, and environmental problems have become the first issue to be considered in production. for that reason,
Since "environmentally friendly products" are required, it is also an important issue to recycle, that is, to use materials that can be easily recycled.

By the way, a plastic product that is processed into an industrial product by processing resources such as petroleum and ore is easy to process.
It is inexpensive and has excellent durability, so it has a wide range of applications.
Since it is a social demand to use a material that can be easily recycled for this plastic product as well, it is desired to use a polyolefin resin such as polypropylene that is easily recyclable among plastics.

[0004] Further, the polyolefin resin has a high specific gravity (polypropylene: 0.91, polyethylene: 0.93) because the molar ratio of hydrogen atoms to carbon atoms is 2: 1 and the ratio of hydrogen atoms is high, and polypropylene resin is a plastic. It has the advantage of being the lightest of all. Further, the polyolefin-based resin is excellent in abrasion resistance, water resistance, chemical resistance, electrical resistance, and the like, and has an advantage that the price per unit volume is low because of its light specific gravity.

However, since the polyolefin resin has a high molding shrinkage ratio, the dimensional accuracy is not stable, warpage and sink marks are likely to occur, and the adhesiveness of secondary processing (painting, printing, bonding, etc.) is poor. Although the molding surface has gloss, it has a drawback that it is weak in scratching and easily scratched.

[0006] In particular, a molded product using a recycled resin material obtained by recycling a waste material of a polyolefin-based resin has stones, sink marks, weld lines, etc., and the appearance is deteriorated. It cannot be used in products. A method of painting the surface to improve the appearance is also conceivable, but since painting is generally done by a spray method using an organic solvent, it leads to environmental pollution.
Since it takes a lot of space and time for drying, the economy is poor. Also, it is difficult to cover sink marks and weld lines even when trying to restore the surface by painting,
There are inconveniences such as easy cracking and brittleness.

In order to solve these problems, one surface of a polyolefin-based resin substrate is embossed to form irregularities, and colored polyolefin-based resin surface sheets may be laminated and integrated as needed. Conceivable.

[0008] For example, Japanese Patent Laid-Open No. 59-39535 discloses a laminated sheet comprising a base sheet made of a resin such as polyethylene, polypropylene, an ethylene copolymer or a propylene copolymer, a metallic layer and a clear sheet. Is molded in advance, and the laminated sheet is mounted on an injection molding die, and the base resin is injected and filled into the die to integrally form the base and the laminated sheet, thereby obtaining a structure. It is disclosed. This laminated sheet is for giving a metallic feeling, and as a mold for injection molding, one having an uneven surface on the mounting surface of the laminated sheet is used to emboss the surface of the laminated sheet during injection molding. . However, when embossing is performed using a mold in this way, the manufacturing cost of the mold is high, which is a cost disadvantage.

Further, Japanese Patent Laid-Open No. 62-212114 discloses a PV.
A sheet made of resin such as C, polyethylene, polypropylene, ABS, etc., the surface of which is embossed and / or printed, is preformed, and the sheet is mounted on an injection molding die to form a substrate. There is disclosed a structure obtained by integrally molding a base and a sheet by injecting and filling a molding resin into the mold. This sheet is for surface decoration, and is embossed to make the surface uneven before the sheet is preformed. However, if this uneven sheet is used for injection molding as it is, the unevenness is thermally deformed. Therefore, in this method, a mold release agent is applied to the uneven surface before injection molding to prevent the deformation by filling the concave portion. , The mold release agent is removed after injection molding. Therefore, the efficiency is poor because an extra step is included, and the economical efficiency is poor because a release agent is used.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to efficiently and cost-effectively provide a polyolefin resin structure comprising a polyolefin resin substrate and a polyolefin resin surface sheet. It is to provide a manufacturing method.

[0011]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. The present invention is a method for producing a polyolefin-based resin structure in which a polyolefin-based resin substrate and a polyolefin-based resin top sheet having irregularities formed by embossing on one side are integrally laminated, The step of forming a molten polyolefin-based resin for a sheet into a sheet by calendering (A-1), and the step of embossing using an embossing roll to give unevenness to one side of the sheet (A-2). Including surface sheet manufacturing process (A)
And a step (B-1) of cutting the topsheet obtained in the step (A), a step (B-2) of preforming the cut topsheet, and a preformed topsheet, The surface sheet is mounted on an injection molding die in such a direction that the surface opposite to the concave-convex surface of the mold is in contact with the resin to be injected and then the molten polyolefin resin for the substrate is injected and filled into the cavity of the mold. Of integrally molding the base with the base (B-3)
There is provided a method for producing a polyolefin-based resin structure, which comprises the step (B) of producing a structure including The present invention also provides a method for producing a polyolefin-based resin structure in which a polyolefin-based resin substrate and a polyolefin-based resin top sheet having embossed unevenness on one surface are laminated and integrated. , A step of forming a molten polyolefin-based resin for a surface sheet into a sheet by calendering (A-1), and a step of embossing using an embossing roll to give unevenness to one side of the sheet (A-2 ) Including the manufacturing step (A) of the topsheet, and the step (B-1) of cutting the topsheet obtained in the step (A), the cut topsheet is injection-molded with an exhaust hole. The surface sheet is preliminarily molded by mounting it in a mold in such a direction that the surface opposite to the uneven surface of the sheet comes into contact with the resin to be injected and filled, and then the surface sheet is preformed, and then the cavity of the mold is formed. Including a step (B-4) of integrally molding the surface sheet and the substrate by injection-filling a molten polyolefin resin for the substrate therein, the structure manufacturing step (B), characterized by the polyolefin A method for manufacturing a resin-based structure is provided. Hereinafter, the present invention will be described more specifically.

[0012] The polyolefin resin which is the material of the top sheet of the top sheet present invention, ethylene, propylene, 4-methyl-1-pentene, 1
-A polymer obtained by polymerizing an olefin such as an α-olefin having 4 to 10 carbon atoms such as butene.
Specific examples include polyethylene, polypropylene, ethylene-propylene random copolymers, ethylene-propylene block copolymers, ethylene-α-olefin copolymers and the like. As these polyolefin-based resins, both virgin materials and recycled materials can be used.

To these polyolefin resins, known additives generally added to thermoplastic resins, for example,
Stabilizers, antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, surfactants, fillers, colorants and the like may be optionally blended according to the purpose, but in blending the additives, It is necessary to consider the type of additive, the amount of the additive, etc. so as not to impair the object and effect of the invention. Also, by blending a resin with a heat-resistant filler, the heat resistance of the obtained sheet can be improved, so that the accuracy of embossing can be improved and even a sheet with a small thickness can be injected as described below. It is possible to prevent breakage of the sheet and deformation of unevenness during molding. As such a filler having a heat resistance effect, for example, a fine particle material such as calcium carbonate, kaolin, mica, talc and the like can be mentioned, and the blending amount of the filler is a base material (polyolefin resin and other optional additives). It is preferably 5 to 10% by weight relative to Further, if the influence on the environment is excluded, aluminum flakes, mineral substances such as glass fibers, asbestos, glass fiber substances, materials such as carbon black may be used.

The surface sheet has one surface provided with unevenness such as a grain pattern by embossing. The thickness of the topsheet is usually 100-1000 μm, preferably 1
It is from 00 to 300 μm. If the sheet is too thick, the tensile strength of the film becomes too high, so that it is difficult to soften and molding becomes difficult, and the adhesiveness to the base resin also decreases. If the sheet is too thin, the tensile strength of the film will be too low and it may not be able to withstand the shear stress of the base resin injected and filled in the injection molding described later, and it may break. Becomes difficult to form.

The topsheet may be a transparent sheet. In the case of forming a transparent sheet, it is preferable to use a virgin material as a raw material resin in order to improve transparency and appearance quality. Further, in the case of a transparent sheet, it is preferable that printing is performed on the surface which is not embossed by embossing. By laminating such a printed transparent sheet on the substrate, it becomes easier to hide the substrate on the printed surface, and the appearance becomes more excellent.
Moreover, since the sheet is laminated on the substrate so that the printed surface of the sheet contacts the substrate, the printed surface is protected.

Further, when a transparent sheet having embossed unevenness on one side and printing on the surface not having the unevenness is used as the surface sheet, the transparent sheet is a polyolefin having a color. It is preferably used as a laminated sheet laminated on a base sheet made of a resin. By forming a transparent sheet on a base sheet, the printing surface of the transparent sheet is protected by the base sheet during injection molding for integral molding with the base body described later, and is hindered by the resin injected and filled. Never. Further, by using such a laminated sheet, the concealing property of the substrate can be further enhanced, and a desired color can be obtained by changing only the color of the base sheet without changing the color of the substrate. It is possible and the cost can be reduced. When using a laminated sheet, the thickness of the transparent sheet is usually 30 to 100 μm.
m, preferably 50 to 150 μm, and the thickness of the base sheet is usually 30 to 970 μm, preferably 50 to 150 μm. The transparent sheet preferably uses a virgin material as the raw material resin as described above, but the base sheet may be either a recycled material or a virgin material. Also,
The base sheet is colored by mixing a raw material resin with a colorant such as a pigment. When a recycled material is used as the raw material resin, a colorant darker than the color of the recycled material is used.

Manufacturing step (A) of surface sheet : Step (A-1) First, various additives are blended with the raw material resin as needed, and after mixing, they are melted and rolled into a sheet. Such molding is performed by calender molding in terms of forming a uniform surface. Calender molding is a method of rolling between two or more heated rolls to continuously form a sheet, and the number of calender rolls and the roll arrangement are not particularly limited. Further, the calender molding conditions can also be carried out under the conventional calender molding conditions of a general polyolefin resin, for example, the roll temperature varies depending on the type of resin used, but in the case of polypropylene, usually,
180-195 ° C. The width of the obtained sheet is usually 1000 to 1200 mm.

Step (A-2) Next, the sheet obtained by the above-mentioned roll forming is embossed to make unevenness on one surface. Embossing is a process of applying pressure to a sheet heated to an appropriate temperature with an embossing roll to form an uneven relief pattern such as a texture pattern on the surface, and the heating temperature of the sheet is equal to or higher than the softening temperature of the sheet. Well, usually 180-195 ° C. In addition, the unevenness depth can be set as appropriate, and when it is desired to make it fine (for example, graininess), the unevenness depth becomes small, and when it is desired to make it rough, the unevenness depth becomes large. Especially,
When printing on the surface of a sheet that does not have unevenness, taking into account the depth (three-dimensional effect) produced by the synergistic effect of unevenness and printing, the unevenness depth is good, and the surface is easily scratched. From the viewpoint of preventing the thickness, 40 to 50 μm is preferable.

When the sheet is subjected to printing such as a stone pattern, it is applied to the surface to which no unevenness is given before embossing the sheet. As a printing method, gravure printing is preferable in that a wide sheet can be printed, a long sheet can be printed, multicolor printing can be performed, and productivity is high. Gravure printing is a type of intaglio printing that fills the depressions on the printing cylinder (plate) with ink, scrapes off excess ink in the ridges with a doctor knife, and leaves the sheet in the depressions between the printing cylinder and the impression copper. It is a method of adhering the ink to the sheet. For multicolor printing, a drum type gravure printing machine can be used. Further, if necessary, characters may be printed by offset printing, silk screen printing, or the like.

When a laminated sheet obtained by laminating the above-mentioned transparent sheet on the base sheet is used as the surface sheet, the transparent sheet and the base sheet are laminated and integrated by thermocompression bonding by roll processing or the like. be able to. In this case, the transparent sheet is laminated and integrated so that the printed surface is in contact with the base sheet. The temperature of the bonding surface between the transparent sheet and the base sheet during thermocompression bonding varies depending on the raw material resin, but when polypropylene resin is used, it is usually 150 to 160 ° C. The temperature of the uneven surface of the transparent sheet may be a temperature at which the unevenness is not deformed, and is usually 160 ° C or lower.

Process (B) for manufacturing the structure : The surface sheet having one surface having irregularities and printed as necessary as described above is contacted with the polyolefin resin substrate with the surface having no irregularities. A structure is obtained by laminating and integrating as described above. Hereinafter, a method for manufacturing this structure will be described.

Step (B-1) First, the surface sheet has an appropriate shape and size according to the shape and size of the surface of the member to which the structure is applied, in consideration of physical properties such as thermal expansion coefficient of the sheet. Cut into pieces. If the sheet is not cut into a proper size, wrinkles, curling, etc. will occur when integrally molded with the substrate, and the finished state of the surface will deteriorate.

Step (B-2) The cut sheet obtained in the step (B-2) is preformed. Preforming is performed by vacuum forming or heat processing at 160 ° C or lower.
For example, in the case of preforming by vacuum forming, the unevenness of the surface sheet is formed on the flat surface of the vacuum forming mold that is maintained at a temperature at which the polyolefin resin softens, for example, in the case of polypropylene resin, at about 100 to 120 ° C. By arranging so that the surfaces not marked with are in contact, and then evacuating,
The topsheet is molded by drawing it onto a die that has a molded product facing the flat portion so that the uneven surface of the sheet is in contact. At this time, the temperature of the mold taken from the molded product is usually 160 ° C.
Hereafter, preferably, the temperature is set to about 50 to 80 ° C. to prevent the deformation of the unevenness. The degree of vacuum is usually 0.7 to 0.97.
mmHg, and the exhaust time is usually
5 to 10 seconds.

When preforming by thermal processing, the temperature
In a concave mold having a temperature of 160 ° C or less, preferably about 50 to 80 ° C, the uneven surface of the surface sheet is placed in contact with the mold surface, and the temperature of the surface sheet is 100 to 120 from the surface side having no unevenness.
It is performed by pressing with a convex mold at about ℃.

Step (B-3) The preformed sheet is mounted in an injection molding die in such a direction that the surface of the sheet having no unevenness is in contact with the resin for a substrate to be injected and filled. The temperature of the mold on which the sheet is mounted varies depending on the type of resin used, but is a temperature at which the irregularities are not deformed, specifically 160 ° C. or lower, more preferably 50 to 80 ° C. Further, the temperature of the mold to which the base resin is in contact is usually 100 to 120 ° C. when polypropylene is used as the raw material resin.

Subsequently, a molten polyolefin resin for a substrate is injection-filled in a cavity of a die in which the sheet is mounted, and the sheet and the molten resin are joined and integrated by the thermal energy and pressure to manufacture a structure. To be done. Here, the resin to be filled is a polyolefin resin, and any of the same resins as the above-mentioned resin for the surface sheet can be used. Further, known additives to be added to general thermoplastic resins may be blended with these resins, and examples of the additives include those exemplified as the additives in the surface sheet. Further, when the structure is desired to have heat resistance, it is preferable to incorporate the heat resistant filler as exemplified in the surface sheet. As the conditions for injecting and filling the molten base resin, the conditions generally used as injection molding conditions for polyolefin resins can be used as they are. Specifically, in the case of polypropylene, the resin temperature is usually 180 to 200 ° C. Also, the injection pressure depends on the size of the molding machine,
Normally, 2100 kg / cm ^{2 for} a 170-ton class molding machine
It is a degree. The injection speed is usually 120 to 190 cm ³ / sec. Furthermore, the temperature in the cylinder of the injection molding machine is usually 1 when polypropylene is used as the raw material resin.
50 to 180 ° C.

Step (B-4 ) Further, instead of the above steps (B-2) and (B-3), the above step (B-4)
-1) Attach the cut sheet obtained in 1) to an injection-molding die provided with an exhaust hole in such an orientation that the surface of the sheet with no irregularities is in contact with the resin to be injected and filled, and then vacuum exhaust. To preform the sheet in the mold by injection molding, and then injection-fill the molten polyolefin resin for the substrate into the mold to integrally form the sheet and the substrate to produce a structure. can do. In this method, an injection mold is used in which an exhaust hole is provided in the mold on which the sheet is mounted, and a vacuum mechanism for exhausting air from the mold cavity is further provided. The vacuum molding conditions and injection molding conditions are the same as the above steps.
The same as (B-2) and (B-3).

In addition, in the step (B-3) or the step (B-4), in order to improve the appearance of the surface of the resulting structure and prevent the surface sheet from being turned over or wrinkles, a gate is provided. A direct gate provided on the substrate side opposite to the surface sheet, that is, on the substrate surface of the structure is preferable. As the gate, any one such as a pin gate can be used. However, when the pin gate is adopted, the resin injected from the cylinder concentrates on one point of the surface sheet and hits the pressure of the resin flowing into the cavity at that point. May have an adverse effect on the surface sheet, such as unevenness or damage on the printed surface or the uneven surface. As a countermeasure, there is a method of increasing the cross-sectional area of the gate or increasing the number of gates. However, in the case of a gate with a circular cross-sectional shape, increasing the cross-sectional area makes it difficult to cut the gate after molding, and increasing the number of gates increases the number of gates to be cut after molding. There is also an inconvenience that the number of man-hours for the gate processing increases. Therefore, as the gate, the tip portion thereof continuously expands from the sprue side toward the cavity side, and the cross-sectional shape of the tip portion is an elongated shape such as a horizontally long rectangular shape or an elliptical shape as shown in FIG. It is preferable to use one. By making the cross-sectional shape elongated, it is possible to increase the cross-sectional area while keeping the gate width small, making it easier to cut the gate after molding and reducing the number of gate processing steps. Excellent production efficiency. In order to facilitate the cutting of the gate, the maximum width w of the gate in the lateral direction is usually preferably about 2 to 3 mm. The gate can also be obtained by using a gate whose tip portion continuously expands from the sprue side toward the cavity side and whose cross-sectional shape is a cross shape as shown in FIG. Although the cross-sectional area can be increased, the gate is slightly more difficult to cut as compared with an elongated cross-sectional shape.

In this way, a polyolefin resin structure is obtained. According to the manufacturing method of the present invention, since the embossing of the surface sheet is performed in advance before injection molding,
It is not necessary to use an injection mold having unevenness. Therefore, since it is not necessary to make unevenness on each of the injection molds according to the shape, size, etc. of the structure, it is efficient, and the manufacturing cost of the mold can be reduced.

Since the structure obtained by the manufacturing method of the present invention is laminated with the surface sheet having irregularities, it is possible to cover the sink mark and the weld line of the substrate made of recycled resin, and also the appearance. It will be excellent. Moreover, since the substrate is laminated with a sheet, the resin used for the substrate may have any color. Furthermore, since the surface decoration of the structure itself can be easily changed by changing the color, pattern, etc. of the sheet, it is possible to manufacture various designs with a single injection molding die, and improve the efficiency. good. In addition, since the material of the sheet and the base material is the same polyolefin resin, it is possible to reduce the weight and cost, and an adhesive is not required when laminating and integrating, and the recycling is easy. It also has the effect. Further, since the sheet is embossed, it has a high surface hardness, is less likely to be scratched, and is effective in preventing whitening. Furthermore, the sheet can cover sink marks and welds, and even if you want to color it, you can print the sheet, so there is no need to spray-paint with an organic solvent, it does not pollute the environment, and it is cost effective. Is also advantageous.

Such a structure can be applied to products using plastic such as home electric appliances, office automation equipment and vehicle equipment.

[0032]

Embodiments of the present invention will now be described in more detail with reference to FIGS. However, the present invention is not limited to this. [Embodiment 1] FIG. 1 is a side view showing the structure of a structure 1 manufactured in this embodiment. The structure 1 according to the present embodiment is
A base sheet 10 made of polypropylene resin (hereinafter referred to as PP resin), and a topsheet 20 made of PP resin having an embossed surface 24 having an embossed surface on one side, the surface sheet 20 having the surface. The surface sheet 20 and the base body 10 are laminated and integrated so that the back surface of the textured surface 24 of the sheet 20 contacts the base body 10. The topsheet 20 includes a translucent transparent sheet 26 having an embossed surface 24 and a base sheet 28 laminated and integrated with the substrate 10. The transparent sheet 26 is printed on the back surface of the uneven surface 24. The transparent sheet 26 and the base sheet 28 are laminated and integrated via the printing surface 32. In this embodiment, the transparent sheet 26 has a thickness of 125 μm, the base sheet 28 has a thickness of 145 μm, and the total thickness of the topsheet 20 is 270 μm. Further, in the present embodiment, the thickness of the base body is set to about 3 mm, but it can be set appropriately according to the member to be applied.

The method of manufacturing the structure 1 of this embodiment will be described in detail based on FIG. 2 and with reference to FIGS. First, FIG.
In the method of manufacturing the PP resin structure, a sheet manufacturing process 1000 for forming the topsheet 20 and a structure manufacturing process 2000 for integrally forming the topsheet 20 and the base body 10 to form a structure are described. To be done. In addition, a desired product is obtained by a product assembling step 3000 of assembling each of the obtained structures. When a product using the PP resin structure is distributed to the market and discarded, a product having recyclable physical properties is collected and crushed in a pulverizing process 4000.
After that, the sheet is supplied to the sheet manufacturing process 1000 or the structure manufacturing process 2000 for recycling. On the other hand, for example, those that do not have the physical properties as the PP resin structure due to being recycled a plurality of times are incinerated or landfilled in the incineration step 4500.

In this example, in manufacturing the structure 1,
In the sheet manufacturing process 1000, first, the PP resin melted in the PP resin melting process 1100 is calendered in the next sheet manufacturing process 1200 to create a sheet. In this embodiment, since the topsheet 20 is a laminated sheet,
In this sheet creating step 1200, a transparent sheet creating step 1210 for creating the transparent sheet 26 and a base sheet creating step 1220 for creating a base sheet are performed. Also,
In the sheet forming process 1200, the melted PP resin is calendered, for example, roll diameter 610 mm (12 inches), number of rolls 4, roll arrangement reverse L shape, roll temperature 1
It is rolled and formed into a sheet by a 90 ° calender forming machine.
Here, the transparent sheet 26 is formed into a sheet having a thickness of 125 μm by using a transparent virgin material of PP resin in order to improve transparency and appearance quality. The base sheet 28 is made of a PP resin virgin material or a recycled material filled with a pigment to form a sheet having a thickness of 145 μm. When the recycled material is used for the base sheet 28, a pigment darker than the recycled material is filled. Next, the obtained transparent sheet 26 has a stone pattern printed by gravure printing on one surface of the transparent sheet 26 in a sheet printing processing step 1300, and next, in a sheet embossing step 1400, the transparent sheet 26 An embossing roll having a roll temperature of 160 ° C. is used to form an uneven pattern on the non-printed surface. In this embodiment, the uneven pattern is a uniform grain pattern.

Next, in the lamination integration process 1500,
The transparent sheet 26 on which the uneven pattern and the printing are applied and the base sheet 28 are thermocompression bonded by a roll process or the like so that the base sheet 28 and the printed surface 32 are in contact with each other. Here, PP resin is 1
Deformation occurs at around 60 ° C. Therefore, during thermocompression bonding, the embossed surface 24 is deformed by setting the adhesive surface from 150 ° C to 160 ° C and the embossed surface 24 side lower than 160 ° C. Glue both sheets together.
Next, a manufacturing process 2000 of a structure using the surface sheet 20 will be described in detail. First, the topsheet 20 is
In the sheet cutting step 2100, the sheet is cut into the size of the molded product in consideration of the size of the structure, the coefficient of thermal expansion, and the like. Next, in the sheet molding step 2200, pre-molding prior to injection molding is performed. This preforming is performed by a vacuum forming method or thermal processing at 160 degrees or less. When the vacuum molding method is used, a temperature at which the PP resin is softened, for example, 100 to
The surface sheet 20 is arranged so that the base sheet 28 side is in contact with the flat surface portion of the vacuum molding die kept at 120 ° C., and then vacuum exhaust is performed, so that the surface sheet 20 faces the flat surface portion 137. Then, the sheet is drawn so that the transparent sheet 26 side of the sheet contacts the die. At this time, the temperature of the mold for which the surface cover 137 is molded is set to about 50 to 80 ° C. to prevent the unevenness from being deformed. In the case of preforming by heat processing, the transparent sheet 26 is placed in a concave mold at a temperature of about 50 to 80 ° C.
The side is in contact with the surface of the mold, and the base sheet 28 side is pressed by a convex mold having a temperature of about 100 to 120 ° C.

Next, the preformed topsheet 20 is
In the step 2300 of mounting the sheet in the mold, the base sheet 28 is mounted in the mold in such an orientation that the base sheet 28 side is in contact with the resin to be injected and filled next, and the step of injecting the base resin into the mold 24
At 00, the PP resin to be the base 10 is injection-molded so that the surface sheet 20 and the base 10 are laminated and integrated. Step 2400 of injecting the base resin into a mold
Will be described in detail with reference to FIGS. 3 and 4.

FIG. 3 is a sectional view showing the outline of the injection molding die, and FIG. 4 is a central sectional perspective view showing the outline of the vicinity of the gate of the injection molding die. In the figure, the injection molding die is composed of a die A on which the topsheet 20 is mounted and a die B having a gate 50, and the melted base resin is transferred from the cylinder 52 through the gate 50. Supplied into the mold cavity. In this injection molding, the topsheet 20
The temperature of the mold A which is in contact with is 160 ° C. or lower, for example, 5
The temperature of the mold B on the substrate side is set to 10 ° C by setting it from 0 ° C to 80 ° C.
0 ℃ to 120 ℃, cylinder temperature from 150 ℃ to 18 ℃
The temperature is set to 0 ° C., the surface sheet 20 is mounted on the mold A, and the tip portion 5 from the cylinder 52 as shown in FIG.
No. 1 spreads continuously from the sprue side toward the cavity side, that is, in a fan shape, and the resin 50 passes through the gate 50 whose cross-sectional shape of the tip portion is a substantially oblong rectangular shape.
It is integrally molded by injection at an injection pressure of 0 kg / cm ² to 1000 kg / cm ² .

Here, in this embodiment, since the thickness of the topsheet 20 is set to be small, a gate 50 having a substantially horizontally long rectangular cross section in which thin slits are formed on both sides of a small circular hole is used. doing. A circular pin gate 60 (Fig. 4
In the case of using the above-described gate 50 adjacent to the gate 50, the base resin supplied from the cylinder 52 hits the narrow range Q2 of the base sheet 28 through the thin pin gate 60 according to the arrow Y2 and spreads around. Flow into the cavity. Therefore, if the topsheet 20 is thick, there is no problem, but for the topsheet 20 that is thin as in this embodiment, the range of the base sheet 28 that directly receives the pressure of the inflowing base resin is the range Q2. Since it becomes narrower, depending on the injection pressure, the range Q
It is conceivable that a portion of the second base sheet 28 is damaged, for example, the base sheet 28 becomes thinner than other portions due to melting, and the printed surface 32 and the embossed surface 24 on the back surface of the transparent sheet 26 are affected. As measures against these problems, it is conceivable to reduce the injection pressure or thicken the base sheet 28. However, if the injection pressure is decreased, it takes a long time for the inflow to cause welds. Thickening results in surface sheet 2
0 will increase the thickness. Furthermore, it is possible to increase the diameter of the pin gate 60 or increase the number thereof, but this increases the number of man-hours for removing the gate, resulting in poor efficiency.

On the other hand, according to the gate 50 as described above,
The base resin supplied from the cylinder gradually spreads in a fan shape along the inner wall of the gate according to the arrow Y1, collides with a wide area Q1 of the base sheet, spreads around, and smoothly flows into the cavity without causing turbulent flow. Therefore, as compared with the conventional example, the range Q1 of the base sheet 28 that directly receives the pressure of the inflowing base resin is widened, so that the influence of the injection pressure is received with a wide Q1, and the influence on the surface sheet 20 is affected. Can be reduced. Furthermore, the remaining material of the gate 50 remaining on the substrate 10 is in the form of a thin plate, and can be easily removed.

As described above, according to this embodiment, since the embossed surface 24 of the transparent sheet 26 is in contact with the mold having a low temperature, the uneven pattern is less likely to be deformed.
The printed surface 32 is protected by the base sheet 28 and is not damaged by the injected resin, and the resin base side of the base sheet 28 is melted and integrally formed with the base 20. In addition, the tip such as the gate 50 is continuously expanded from the sprue side toward the cavity side, and by adopting a gate having an elongated cross-sectional shape, the die can be easily changed. The obstacles of the base sheet 28 can be reduced, and as a result, the topsheet 20 can be made thinner. In this embodiment, the gate 50 as described above is used to form the surface cover 137 in which the surface sheet 20 used in the portable word processor is thinned. However, the thickness of the surface sheet may be increased, or For other large molded products, the conventional pin gate 60
Or other gates may be used.

At the end of the structure completing step 2500, the gate 50a, burrs and the like are removed to complete the structure 1.

[Embodiment 2] FIG. 5 is a side view showing the structure of the structure 2 manufactured in this embodiment. The structure 2 according to the present embodiment includes a base 10 made of PP resin and an embossed surface 24 having an uneven surface formed by embossing on one surface.
And a translucent surface sheet 72 made of a PP resin as a material.
Is provided with a printing surface 32 printed on the back surface of the
The sheet 20 and the base 10 are laminated and integrated so that the sheet 2 and the base 10 are in contact with each other. The topsheet 72 has a thickness of about 100 μm to 1000 μm, and the thickness of the substrate is set appropriately. Also, the surface sheet 7
When the curved surface or a large bend is required, the thickness 2 is set to, for example, about 100 μm to 300 μm so as to reduce the wrinkles at the time of preprocessing the topsheet 72. In addition, a thick sheet may be used to obtain a pattern that is stacked on a flat surface and further emphasizes the depth feeling.

Further, the one-layer type surface sheet 7 as described above is used.
When 2 is used, it is advisable to add a filler having a heat resistance effect to the raw material resin so as to reduce the thermal influence on the sheet during injection molding. By doing so, the accuracy of embossing can be improved and the thickness of the sheet can be reduced. As a filling material, for example, calcium carbonate, kaolin, mica, talc or other fine particle material having a heat-resisting effect is blended in an amount of 5 to 10% by weight with respect to the base material so that recycling and environmental friendliness can be prevented. be able to. Further, if the influence on the environment is excluded, aluminum flakes, mineral substances such as glass fibers, asbestos, glass fiber substances, materials such as carbon black may be used.

FIG. 6 shows a manufacturing process of a product provided with the structure 72. In this manufacturing process, the surface sheet manufacturing process in the manufacturing process shown in FIG. 2 is different. Top sheet manufacturing process 1000a in this embodiment
Then, the PP resin melted in the polyolefin resin melting step 1100 is calendered into a sheet forming step 120.
Only the transparent sheet 72 is prepared with 0a, and the surface sheet is completed through the sheet printing process 1300 and the sheet embossing process 1400. Therefore, in the manufacturing process of the topsheet 72, the number of steps is 2
The number of steps can be reduced. Note that other manufacturing steps are omitted because they are similar to those in FIG. Further, in FIG. 7, the surface sheet manufacturing process is the same as the process shown in FIG. 6, and the structure manufacturing process is different from the structure manufacturing process 2000 of FIGS. 2 and 6. In the manufacturing process 2000a of this structure, the sheet 72 cut according to the size of the product in the sheet cutting process 2100 is directly used as a mold by omitting the sheet forming process 2200 shown in FIGS. 2 and 6. The step 2300 of attaching the sheet to be attached to the mold is performed. The mold used here is an injection mold provided with an exhaust hole and further provided with a vacuum mechanism for exhausting air from the mold cavity. Then, in the vacuum forming step 2250 of the sheet, the sheet is pre-processed in the injection molding die by vacuum evacuation to bring the sheet into close contact with the die. Then, a step 2400 of injecting the base resin into the mold,
Structure manufacturing process 200 through structure completion process 2500
0a is completed. According to this manufacturing process, it is possible to reduce the number of processes by two as compared with the processes shown in FIGS. This manufacturing process is suitable for molding a large number of molded products. The sheet manufacturing process 1000 of FIG. 2 and the structure manufacturing process 2000a shown in FIG. 7 may be combined. In the structure shown in FIG. 1 and FIG. 5, the surface sheet is a transparent sheet, but if the surface is provided with a textured surface by embossing, it is hard to be scratched and has a structure excellent in environment and recyclability. You can get the body.

[0045]

According to the present invention, a polyolefin resin structure comprising a polyolefin resin substrate and a polyolefin resin surface sheet can be produced efficiently and cost-effectively. Productivity is improved.

[Brief description of the drawings]

FIG. 1 is a side view showing a structure of a structure 1.

FIG. 2 is a diagram showing an example of a manufacturing process of a structure of the present invention.

FIG. 3 is a cross-sectional view schematically showing an injection molding die.

FIG. 4 is a central cross-sectional perspective view schematically showing the vicinity of the gate of the injection mold.

5 is a side view showing the structure of the structure 2. FIG.

FIG. 6 is a diagram showing an example of a manufacturing process of the structure of the present invention.

FIG. 7 is a diagram showing an example of a manufacturing process of the structure of the present invention.

FIG. 8 is a view showing a cross-sectional shape of a gate of an injection molding die.

FIG. 9 is a view showing a cross-sectional shape of a gate of an injection molding die.

[Explanation of symbols]

10 ... Base, 20 ... Surface sheet, 24 ... Concavo-convex processed surface, 2
6 ... Transparent sheet, 28 ... Base sheet, 32 ... Printing surface,
50 ... Gate, 60 ... Gate, 72 ... Surface sheet

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B29C 63/02 9446-4F B29C 63/02 // B29K 23:00 105: 32 503: 04 B29L 9 : 00 (72) Inventor Naruhiko Suzuki 1-1-1 Higashitaga-cho, Hitachi-shi, Ibaraki Electric Company, Hitachi, Ltd.

Claims (14)

[Claims] 1. A method for producing a polyolefin-based resin structure in which a polyolefin-based resin substrate and a polyolefin-based resin top sheet having embossed unevenness on one surface are laminated and integrated. A step of forming a molten polyolefin resin for a surface sheet into a sheet by calendar forming (A-1), and a step of embossing using an embossing roll to give unevenness to one side of the sheet (A-2) Including the step of manufacturing a topsheet (A), and a step of cutting the topsheet obtained in the step (A) (B-1), a step of preforming the cut topsheet (B-2), And the preformed surface sheet is mounted in an injection molding die in such a direction that the surface opposite to the uneven surface of the sheet is in contact with the resin to be injected and filled, and then melted for the substrate in the cavity of the mold. Made poly A method for producing a polyolefin resin structure, characterized by including a step (B) for producing a structure, including a step (B-3) for integrally molding a surface sheet and a substrate by injection-filling an olefin resin. . 2. The polyolefin-based resin structure according to claim 1, wherein, in the step (B-3), the temperature of the mold with which the uneven surface of the topsheet contacts is 160 ° C. or lower. Production method. 3. The method for producing a polyolefin resin structure according to claim 1, wherein in the step (A-1), a polyolefin resin for a surface sheet is blended with a heat resistant filler. 4. In the step (B-3), the gate for introducing the molten polyolefin resin is on the side of the substrate opposite to the surface sheet, and the tip of the gate is from the sprue side to the cavity side. The method for producing a polyolefin-based resin structure according to any one of claims 1 to 3, wherein the tip end portion has a slender shape in cross section. 5. In the step (B-3), the gate for introducing the molten polyolefin resin is on the substrate side opposite to the surface sheet, and the tip of the gate is from the sprue side to the cavity side. The method for producing a polyolefin-based resin structure according to any one of claims 1 to 3, wherein the tip end portion has a cruciform cross section, and the tip end portion has a cruciform shape. 6. A method for producing a polyolefin-based resin structure in which a polyolefin-based resin substrate and a polyolefin-based resin top sheet having embossed unevenness on one surface are laminated and integrated. A step of forming a molten polyolefin resin for a surface sheet into a sheet by calendar forming (A-1), and a step of embossing using an embossing roll to give unevenness to one side of the sheet (A-2) Including the step of manufacturing a surface sheet (A), and a step of cutting the surface sheet obtained in the step (A) (B-1), the cut surface sheet being an injection molding die provided with an exhaust hole. The surface sheet is preliminarily molded by mounting the mold in such a direction that the surface opposite to the uneven surface of the sheet is in contact with the resin to be injected and filled, and then the surface sheet is preformed, and then the inside of the cavity of the mold. A process of injection-filling a molten polyolefin resin for a substrate into a top sheet and integrally molding the surface sheet and the substrate
A method for producing a polyolefin-based resin structure, comprising the step (B) for producing a structure, which comprises (B-4). 7. The polyolefin-based resin structure according to claim 6, wherein in the step (B-4), the temperature of the mold with which the uneven surface of the topsheet contacts is 160 ° C. or lower. Production method. 8. The method for producing a polyolefin resin structure according to claim 6, wherein in the step (A-1), a polyolefin resin for a surface sheet is blended with a heat resistant filler. 9. In the step (B-4), the gate for introducing the molten polyolefin resin is on the substrate side opposite to the surface sheet, and the tip of the gate is from the sprue side to the cavity side. The method for producing a polyolefin-based resin structure according to any one of claims 6 to 8, wherein the tip end portion has a slender shape in cross section. 10. In the step (B-4), the gate for introducing the molten polyolefin resin is on the substrate side opposite to the surface sheet, and the tip of the gate is from the sprue side to the cavity side. The method for producing a polyolefin-based resin structure according to any one of claims 6 to 8, wherein the tip end portion has a cruciform cross section, and the tip end portion has a cruciform shape. 11. The surface sheet is transparent, and the surface opposite to the uneven surface is printed.
The method for producing the polyolefin-based resin structure according to any one of 1. 12. The method according to claim 11, further comprising a step of performing printing by performing printing on one side of the sheet, between the step (A-1) and the step (A-2). A method for producing a polyolefin resin structure according to claim 1. 13. A laminated sheet in which a transparent sheet having an uneven surface formed by embossing on one surface and having a printed surface on the opposite surface to the uneven surface is laminated on a base sheet having colors. The method for producing a polyolefin-based resin structure according to claim 11 or 12. 14. A step of printing by performing printing on one side of the sheet between step (A-1) and step (A-2), wherein a transparent sheet is provided after step (A-2). The method for producing a polyolefin-based resin structure according to claim 13, including a step of laminating and integrating with a base sheet.