JP4388853B2 - Method for producing thermoplastic resin foam molded article - Google Patents

Description

  The present invention relates to a method for producing a thermoplastic resin foam molded article.

  Conventionally, thermoplastic resin foam molded products have been widely used mainly as interior parts for automobiles such as door trims, pillar trims, and quarter trims, separator trays in trunks, and the like from the viewpoint of weight reduction.

  When the thermoplastic resin foam molded product is used for interior parts for automobile interiors, functional members such as reinforcing ribs, bosses for attaching to the vehicle body, clip seats and the like are provided on the back surface of the molded product. As a method for producing a thermoplastic resin foam molded article having such a functional member, for example, as shown in FIG. 1, between a pair of molds 1 and 2 having a recess 3 corresponding to the shape of the functional member. The heated and softened thermoplastic resin foam sheet 4 is supplied, and the mold clearance is clamped until the mold clearance reaches the thickness (predetermined shape) obtained by removing the functional member from the final thermoplastic resin molded product. The thermoplastic resin foam sheet is formed from the thermoplastic resin by supplying the molten thermoplastic resin by injection through the molten resin passage 5 provided in the mold and injecting the molded resin. A method of fusing and integrating functional members is known (see Patent Document 1).

  However, in the above method, when the supply pressure of the molten thermoplastic resin is high, the thermoplastic resin foam sheet 4 is damaged by the supply of the molten thermoplastic resin as shown in FIG. As described above, the molten thermoplastic resin 6 sometimes leaks from the concave portion of the mold to the surface of the thermoplastic resin foam sheet 4. Therefore, development of a method for producing a thermoplastic resin foam molded article having an excellent appearance has been desired.

JP 2001-121561 A

  The objective of this invention is providing the manufacturing method of the thermoplastic resin foam molded article excellent in the external appearance.

That is, the present invention provides a thermoplastic resin foam molded article comprising the following steps in a method for producing a thermoplastic resin foam molded article in which a functional member made of a thermoplastic resin is partially fused: It is a manufacturing method.
(1) A step of heating and softening the raw material thermoplastic resin foam sheet.
(2) Softening in the step (1) between a pair of male and female dies having a molded part for shaping the thermoplastic resin foam sheet and having a concave part corresponding to the shape of the functional member in the molded part Supplying a thermoplastic foam sheet.
(3) A step of once stopping mold clamping after mold clamping until the mold clearance becomes larger than the thickness of the thermoplastic foam sheet softened by heating larger than a predetermined shape thickness.
(4) After the mold clamping is resumed and the mold clearance is clamped so as to have a predetermined shape thickness, or at the same time when the mold clearance reaches the predetermined thickness, it is melted through a resin passage provided in the mold so as to communicate with the recess. Supplying the state of the thermoplastic resin to the recess by rotating the screw of an in-line screw type resin feeder.
(5) A step of cooling the thermoplastic resin foam molded product molded in step (4) and taking it out of the mold.
Furthermore, the present invention provides a method for producing a thermoplastic resin foam molded article in which a functional member made of a thermoplastic resin is partially fused. The method includes the following steps: It is a manufacturing method.
(1) A step of heating and softening the raw material thermoplastic resin foam sheet.
(2) Softening in the step (1) between a pair of male and female dies having a molded part for shaping the thermoplastic resin foam sheet and having a concave part corresponding to the shape of the functional member in the molded part Supplying a thermoplastic foam sheet.
(3) After clamping so that the mold clearance becomes a predetermined shape thickness, or at the same time as the predetermined shape thickness,
(4) A step of supplying a molten thermoplastic resin to the concave portion by rotating the screw of an in-line screw type resin feeder through a resin passage provided in the mold so as to communicate with the concave portion.
(5) A step of cooling the thermoplastic resin foam molded product molded in step (4) and taking it out of the mold.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the manufacturing method of the thermoplastic resin foam molded product excellent in the external appearance.

  The thermoplastic resin constituting the raw material thermoplastic resin foam sheet used in the present invention can be appropriately selected according to the type of thermoplastic resin constituting the functional member fused to the foam sheet. Examples of the thermoplastic resin constituting the raw material thermoplastic resin foam sheet include polyethylene resins, polypropylene resins, polystyrene resins, polyethylene terephthalate resins, polyvinyl alcohol resins, vinyl chloride resins, ionomer resins, acrylonitrile- Examples thereof include butadiene-styrene resin. The thermoplastic resin foam sheet may be composed of two or more kinds of thermoplastic resins, and may be the same or different multilayer thermoplastic resin foam sheets.

  The thermoplastic resin constituting the raw material thermoplastic resin foam sheet is preferably a polypropylene resin from the viewpoint of heat resistance and cost. Examples of the polypropylene resin include a propylene homopolymer, a copolymer containing 50 mol% or more of a propylene-derived structural unit, and the like. Examples of the copolymer component of propylene in the copolymer include α-olefins having 2 or 4 to 10 carbon atoms. Examples of the α-olefin having 2 or 4 to 10 carbon atoms include ethylene, 1-butene, 4-methylpentene-1, 1-hexene, 1-octene and the like. The content of the copolymer component in the copolymer is preferably 10% by weight or less when the copolymer component is ethylene, and when the copolymer component is an α-olefin having 4 to 10 carbon atoms, It is preferable that it is 30 weight% or less.

  As the polypropylene resin, a polypropylene resin into which long chain branching is introduced by low-level electron beam crosslinking is preferably used (see JP-A-62-1121704). In addition, a polypropylene resin into which an ultrahigh molecular weight component is introduced is also preferably used.

  The raw material thermoplastic resin foam sheet can be produced by melt-kneading a thermoplastic resin and a foaming agent, and extruding and foaming. As the foaming agent, generally used inorganic or organic chemical foaming agents and physical foaming agents such as inert gases such as nitrogen gas and carbon dioxide can be used.

  The foaming ratio of the raw material thermoplastic resin foam sheet is not particularly limited and can be arbitrarily selected according to the target product. From the viewpoint of product rigidity, it is preferably 10 times or less, and the viewpoint of weight reduction of the product Therefore, it is preferably 2 times or more. The thickness of the raw material thermoplastic resin foam sheet is not particularly limited, and an arbitrary thickness can be selected. From the viewpoint of sheet strength and handling, the thickness of the thermoplastic resin foam sheet is preferably 1 mm to 10 mm.

  The thermoplastic resin foam sheet may have a skin material on the surface thereof. Examples of the skin material include woven fabric, non-woven fabric, knitted fabric, sheet, film, and foam. The material constituting these skin materials is not particularly limited. For example, thermoplastic resins such as polyolefin resins, polyvinyl chloride resins and polystyrene resins, thermosetting resins such as polyurethane resins, or Examples thereof include rubbers such as cis-1,4-polybutadiene and ethylene-propylene copolymers, and thermoplastic elastomers. Such a skin material may be provided with an uneven pattern such as embossing, printing or dyeing. The skin material may be a single layer or a multilayer structure composed of two or more layers, and a skin material provided with a polyolefin-based foam layer or a polyurethane-based foam layer is used to give a soft feeling. May be.

  Moreover, you may equip the one surface or both surfaces of the said thermoplastic resin foam sheet with the porous layer. The form of the porous layer is not particularly limited as long as the functional member can be fused to the thermoplastic resin sheet through the porous layer, and has a woven cloth, a non-woven cloth, a net-like material, and a communication hole. Although a foam etc. can be used, a nonwoven fabric is used preferably. Examples of the material constituting the porous layer include thermoplastic resins such as polyolefin resins, polyester resins, polyamide resins, polystyrene resins, natural fibers such as cellulose fibers such as cotton, hemp, bamboo, and the like. Examples include fibers mixed with fibers, metals, and minerals.

  The thickness of the skin material and the porous layer can be arbitrarily selected according to the target product, and the skin material, the porous layer and the thermoplastic resin foam sheet are, for example, a method using an adhesive or welding. These are laminated by the general method.

  The functional member made of a thermoplastic resin in the present invention is formed so as to protrude from the thermoplastic resin foam sheet, and specifically, a rib for reinforcing a thermoplastic resin foam molded article, a thermoplastic resin It is a member such as a boss, a clip, or a hook for attaching the foam molded product to another member.

  The thermoplastic resin constituting the functional member can be appropriately selected according to the type of the thermoplastic resin constituting the thermoplastic resin foam sheet for fusing the functional member. Examples of the thermoplastic resin constituting the functional member include polyethylene resin, polypropylene resin, polyester resin, polyethylene terephthalate resin, polyvinyl alcohol resin, vinyl chloride resin, ionomer resin, polyamide resin, and acrylonitrile. -Butadiene-styrene resins, polycarbonate resins, modified products thereof, polymer alloys composed of two or more of the above resins, and the like. The functional member may be composed of two or more types of thermoplastic resins. The thermoplastic resin that constitutes the functional member is preferably a thermoplastic resin that is compatible with the thermoplastic resin that constitutes the thermoplastic resin sheet, from the viewpoint of fusion strength with the thermoplastic resin foam sheet.

  The thermoplastic resin that constitutes the functional member includes glass fiber, inorganic fiber such as carbon fiber, various fillers such as inorganic particles such as talc, clay, silica, calcium carbonate, antioxidant, colorant, flame retardant In addition, various additives such as a low shrinkage agent may be blended.

  In the present invention, the functional member may be attached to only one surface of the thermoplastic resin foam sheet, or may be attached to both surfaces of the thermoplastic resin foam sheet. Further, the attachment position and the number of attachments are not particularly limited.

  In the mold used in the present invention, at least one mold is provided with recesses corresponding to the number and the shape corresponding to the number and shape of the functional members to be formed. A molten resin passage for supplying a plastic resin is provided.

  An in-line screw type resin feeder is connected to the outer end of the molten resin passage of the mold. The resin feeder is not particularly limited as long as it is an inline screw type resin feeder, and examples thereof include an injection machine and an extruder having an inline screw.

  Next, one aspect of the process of the production method of the present invention will be described.

  Step (1) is a step of heating and softening the raw material thermoplastic resin foam sheet. Examples of the heating means include a far-infrared or near-infrared heater or oven. Although the heating temperature of a raw material thermoplastic resin foam sheet changes with kinds of thermoplastic resin, for example in the case of a polypropylene foam sheet, it is preferable to heat at about 130-160 degreeC.

  The step (2) includes a molding part for shaping the thermoplastic resin foam sheet, and a step (1) between a pair of male and female dies having a concave part corresponding to the shape of the functional member in the molding part. This is the step of supplying the thermoplastic resin foam sheet softened in step ii).

Step (3) is a step in which the mold clearance is temporarily stopped after the mold is clamped until the mold clearance becomes larger than the thickness of the thermoplastic resin foam sheet softened by heating larger than the predetermined shape thickness.
In step (3), the inside of the mold cavity is preferably vacuumed or compressed air is added to the mold cavity.

In the step (4), after the mold clamping is restarted and the mold clearance is clamped so as to have a predetermined shape thickness, or at the same time as the predetermined shape thickness is reached, the resin provided in the mold so as to pass through the concave portion This is a step of supplying a molten thermoplastic resin to the concave portion through rotation of a screw of an in-line screw type resin supply machine through a passage.
In the step (4), the inside of the mold cavity may be vacuumed following the step (3), or compressed air may be added to the mold cavity.

  The molten thermoplastic resin is supplied to the concave portion of the mold by plasticizing and kneading the thermoplastic resin in the barrel as in the case of injection molding using a normal in-line screw type injection device, and the molten thermoplastic resin at the tip of the barrel. If the molten thermoplastic resin collected in the part is supplied by advancing the screw, the supply pressure of the molten thermoplastic resin increases and damage to the thermoplastic resin sheet tends to increase, corresponding to the shape of the functional member It becomes easy for the molten thermoplastic resin to leak out from the mold recess. Therefore, in the present invention, the molten thermoplastic resin is supplied to the concave portion of the mold not by supplying the molten thermoplastic resin accumulated by moving the screw but by rotating the screw without moving forward. Supply thermoplastic resin. By supplying the molten thermoplastic resin by rotating the screw of the resin feeder in this way, it is possible to reduce the supply pressure of the molten thermoplastic resin, and damage the thermoplastic foam sheet. The functional member can be molded without giving the molten thermoplastic resin from the mold recess corresponding to the shape of the functional member.

  When the molten thermoplastic resin is supplied to the mold recess by rotating the screw, the supply pressure of the molten thermoplastic resin can be controlled by various methods such as screw back pressure and screw rotation speed, but can be controlled by the screw rotation speed. preferable. The supply pressure is preferably controlled to be 10 MPa or less, and the rotational speed of the screw is preferably 5 to 100 rpm.

  Although the supply amount of the molten thermoplastic resin can be controlled by any method, it is preferably controlled by the rotation time of the screw.

  Step (5) is a step of cooling the thermoplastic resin foam molded article molded in step (4) and taking it out of the mold. In this way, a thermoplastic resin foam molded article can be obtained.

  Next, the other aspect of the process of the manufacturing method of this invention is demonstrated.

In another aspect of the present invention, the following steps are included.
(1) A step of heating and softening the raw material thermoplastic resin foam sheet.
(2) Softening in the step (1) between a pair of male and female dies having a molded part for shaping the thermoplastic resin foam sheet and having a concave part corresponding to the shape of the functional member in the molded part Supplying a thermoplastic foam sheet.
(3) After clamping so that the mold clearance becomes a predetermined shape thickness, or at the same time as the predetermined shape thickness,
(4) A step of supplying a molten thermoplastic resin to the concave portion by rotating the screw of an in-line screw type resin feeder through a resin passage provided in the mold so as to communicate with the concave portion.
(5) A step of cooling the thermoplastic resin foam molded product molded in step (4) and taking it out of the mold.
The manufacturing method is different from the above-described manufacturing method in steps (3) and (4), but the manufacturing method does not damage the thermoplastic resin foam sheet as in the above-described manufacturing method, and The functional member can be molded without leakage of the molten thermoplastic resin from the mold recess corresponding to the shape of the functional member, and a thermoplastic resin foam molded article having an excellent appearance can be obtained.

  Since the thermoplastic resin molded article thus obtained has a good appearance, it can be suitably used for automobile interior parts such as door trims, pillar trims, quarter trims, and package trays.

  The method for producing a thermoplastic resin foam molded article of the present invention can be obtained by a conventional method, particularly when a thermoplastic resin foam sheet in which a skin material having a foam layer having an expansion ratio of 2 times or more is used as a raw material. Since a thermoplastic resin foam molded article having a better appearance than a molded article can be obtained, it is preferably applied.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited by these Examples.

Example 1
As shown in FIG. 4, a pair of press dies comprising a female die 1 and a male die 2 having a recess 3 corresponding to a rib shape and a molten thermoplastic resin passage 5 (size of molding surface: length 300 mm, width 300 mm, height 10 mm) was used.
As a raw material thermoplastic resin foam sheet, a polypropylene resin foam sheet (manufactured by Sumika Plustech: Sumiceller foam PP sheet 5050, expansion ratio = 5 times, thickness = 5 mm) and an olefin thermoplastic elastomer sheet (made by Kyowa Leather, thickness) = 0.35 mm) was used.
The foamed laminated sheet 4 is heated to 150 ° C. in an oven and placed on the molding surface of the male mold 2 adjusted to 30 ° C. with the elastomer surface facing the female mold, and then the female mold 1 is placed in the clamping direction. The mold was clamped until the mold clearance reached a predetermined shape thickness of 5 mm. After the molded body made of the foamed laminated sheet is cooled in the mold for 10 seconds, the screw of the in-line screw type injection device (not shown) is not advanced, but is rotated at 30 rpm for 5 seconds to provide the male mold 2 Through the resin passage 5, about 50 g of polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd .: AX568, melt flow rate = 65 g / 10 min) melted at 250 ° C. was supplied to the recess 3. After filling the recess 3 with the resin, it was cooled for 20 seconds, and the male and female molds 1 and 2 were opened to obtain a thermoplastic resin foam molded product in which the ribs were fused to the surface of the non-skin. The obtained thermoplastic resin foam molded article did not collapse on the surface of the skin material, and had a good appearance with no resin leakage around the rib portion on the side of the anti-skin material.

Example 2
Using the same press mold as in Example 1, as the thermoplastic resin foam sheet, polypropylene resin foam sheet (manufactured by Sumika Plastics: Sumiceller foam PP sheet 5050, foaming magnification = 5 times, thickness = 5 mm) A foamed laminated sheet in which a laminated skin consisting of an olefinic thermoplastic elastomer sheet (Kyowa Leather, thickness = 0.35 mm) and a highly foamed polypropylene foamed sheet (Toray: PPSM15030, expansion ratio = 15 times, thickness 3 mm) is laminated by heat. Was used.
The foamed laminated sheet 4 is heated to 150 ° C. in an oven, placed on the molding surface of the male mold 2 adjusted to 30 ° C. with the elastomer surface facing the female mold, and then the female mold 1 is placed in the clamping direction. The mold was clamped until the mold clearance reached 8 mm, and the mold clamping was temporarily stopped. After cooling the molded body made of the foamed laminated sheet in the mold for 10 seconds, the female mold is further moved 2 mm in the mold clamping direction so that the mold clearance is 6 mm, which is a predetermined shape thickness. The polypropylene resin melted at 250 ° C. in the concave portion 3 through the resin passage 5 provided in the male mold 2 by rotating the screw for 5 seconds at 30 rpm without moving the screw forward (manufactured by Sumitomo Chemical: AX568, melt flow rate = 65 g / 10 minutes) about 50 g was supplied.
After filling the recess 3 with resin, the resin was cooled for 30 seconds, and the male and female molds 1 and 2 were opened to obtain a thermoplastic resin foam molded product having ribs fused to the surface of the non-skin material.
The obtained thermoplastic resin foam molded article did not collapse on the surface of the skin material, and had a good appearance with no resin leakage around the rib portion on the side of the anti-skin material.

Comparative Example 1
Using the foamed laminated sheet and mold used in Example 1, the molten thermoplastic resin is stored in a barrel so that the molten resin becomes about 50 g by an in-line screw type injection device, and the stored molten thermoplastic resin is Thermoplastic resin foam molding in which ribs are fused to the anti-skin surface of the foamed laminated sheet in the same manner as in Example 1 except that the screw is advanced without rotating and supplied to the recess 3 through the resin passage 5. I got a product. In the obtained thermoplastic resin molded product, the product surface on the opposite rib side was crushed, and the resin supplied to the recess leaked around the rib portion.

It is the schematic of an example of the manufacturing method of the thermoplastic resin foam molded article of this invention. It is the schematic of the other example of the manufacturing method of the thermoplastic resin foam molding of this invention. It is a schematic sectional drawing of the example of a defect of the thermoplastic resin foam molded product by which the functional member was partially provided in the thermoplastic resin foam sheet. It is a schematic sectional drawing of the example of a defect of the thermoplastic resin foam molded product by which the functional member was partially provided in the thermoplastic resin foam sheet.

Explanation of symbols

1: Female mold 2: Male mold 3: Recessed part corresponding to the shape of the functional member 4: Thermoplastic resin foam sheet 5: Molten thermoplastic resin supply passage 6: Molten thermoplastic resin

Claims (2)

A method for producing a thermoplastic resin foam molded article, comprising the following steps in a method for producing a thermoplastic resin foam molded article in which a functional member made of a thermoplastic resin is partially fused.
(1) A step of heating and softening the raw material thermoplastic resin foam sheet.
(2) Softening in the step (1) between a pair of male and female dies having a molded part for shaping the thermoplastic resin foam sheet and having a concave part corresponding to the shape of the functional member in the molded part Supplying a thermoplastic foam sheet.
(3) A step of once stopping mold clamping after mold clamping until the mold clearance becomes larger than the thickness of the thermoplastic foam sheet softened by heating larger than a predetermined shape thickness.
(4) After the mold clamping is resumed and the mold clearance is clamped so as to have a predetermined shape thickness, or at the same time when the mold clearance reaches the predetermined thickness, it is melted through a resin passage provided in the mold so as to communicate with the recess. Supplying the state of the thermoplastic resin to the recess by rotating the screw of an in-line screw type resin feeder.
(5) A step of cooling the thermoplastic resin foam molded product molded in step (4) and taking it out of the mold.   The production method according to claim 1, wherein the raw material thermoplastic resin foam sheet has a skin material and / or a porous layer.

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