JP4486787B2 - Method for producing multilayer molded product - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a multilayer molded article comprising a base material made of a thermoplastic resin and a skin material bonded and integrated on at least a part of the surface thereof.
[0002]
[Prior art]
Conventionally, a multilayer molded article formed by bonding a surface material such as a synthetic resin sheet, a woven fabric or a non-woven fabric to a part of the surface of a base material made of a thermoplastic resin has an economical efficiency, a light weight and a good imparting property. From the viewpoint of shape and the like, it is widely used in automobile interior parts (for example, door trims and instrument panels), interior / exterior parts of home appliances, and other fields.
[0003]
As a method for producing such a multilayer molded article, for example, the one disclosed in Patent Document 1 below is known. In this manufacturing method, as shown in FIG. 5, the skin material 3 is disposed between a pair of male and female molds 1 and 2, and thereafter, from the main resin supply gate 4 provided on the back surface side of the skin material 3, A molten thermoplastic resin (molten resin) 5 as a material is supplied into the cavity 6 between the molds 1 and 2 to produce a multilayer molded product. Here, the “main resin supply gate” means a gate that can supply a large part of the amount of resin necessary for manufacturing the substrate, for example, 60% or more, and an auxiliary resin that compensates for the shortage. It does not include the supply gate. Hereinafter, when simply referred to as “resin supply gate”, “main resin supply gate” is indicated.
[0004]
[Patent Document 1]
Japanese Patent Publication No. 5-39172 [0005]
[Problems to be solved by the invention]
In the conventional method for manufacturing a multilayer molded article as described above, as shown in FIG. 5, when the resin supply gate 4 is formed at a position opposite to the portion where the skin material 3 is disposed, the multilayer is preferably formed. It is possible to produce molded articles.
[0006]
However, depending on the shape and position of the skin material, the resin supply gate may not be provided at a position facing the skin material placement site. For example, as in the case of a multilayer molded article 10 (door trim which is an automobile interior part) 10 shown in FIG. 6, when the skin material 12 is elongated and the position of the bonding portion is a position on the edge of the base material 14. It is difficult to form a resin supply gate at a position facing the skin material arrangement site.
[0007]
When the molten resin is supplied from the resin supply gate located at a position shifted from the skin material arrangement site, the edge of the skin material is pushed and moved by the flow of the molten resin, or the design surface of the skin material ( The molten resin wraps around the (surface) side, and the appearance of the product is impaired.
[0008]
Of course, it is possible to form the resin supply gate so as to face the skin material arrangement portion, but the cost for manufacturing a mold having such a gate becomes enormous.
[0009]
Accordingly, an object of the present invention is to provide a production method capable of producing a good multilayer molded product regardless of the shape and position of the skin material.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a method for producing a multilayer molded product according to the present invention includes (1) a main resin supply gate for supplying a molten thermoplastic resin, and a position away from the resin supply gate. A first mold having a recess, and a second mold that is openable and closable with respect to the first mold and that forms a cavity with the first mold when closed. The second mold having a protrusion provided at a position corresponding to the edge of the skin material in the multilayer molded product after completion of manufacture is prepared at a position facing the recess, and (2) is in an open state. A skin material is disposed at a predetermined position between the first mold and the second mold and away from the portion facing the main resin supply gate beyond the ridge, and the first mold and When the space between the second mold and the second mold is closed, a part of the edge of the skin material contacts the protrusion of the second mold. To, (3), characterized in that narrowed between the first mold and the second mold to supply molten resin from a main resin feed gate to clamping the thermoplastic resin after completion fed in or fed It is said.
[0011]
When a multilayer molded product is manufactured by such a method, the molten resin from the resin supply gate at a position away from the skin material does not directly hit the edge of the skin material due to the presence of the protrusions, The molten resin can be prevented from wrapping around the design surface side of the skin material.
[0012]
In addition, when the molten resin is supplied from the main resin supply gate, it is preferable that the cavity clearance between the first mold and the second mold be smaller than the height of the ridge. This is because the molten resin from the resin supply gate is reliably supplied from the back side of the skin material.
[0013]
Furthermore, it is preferable to arrange the skin material at a predetermined position between the first and second molds so that a part of the edge of the skin material is in contact with the protrusion or is located in the recess. This is for more accurate positioning.
[0014]
As the skin material, it is preferable to use a pre-shaped skin material. This is because the pre-shaped skin material is easy to handle and can be positioned accurately.
[0015]
In order to perform positioning accurately, the skin material may be adsorbed and arranged on the cavity surface of the second mold.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, this embodiment is related with the method of manufacturing the multilayer molded article 10 shown in FIG. 6 demonstrated previously.
[0017]
First, a molding apparatus used for manufacturing the multilayer molded article 10 of FIG. 6 according to the method of the present invention will be described with reference to FIGS. 1 and 2. As shown in the figure, the molding apparatus 20 includes a fixed mold support board 22, a first mold 24 that is a male mold supported on the upper surface of the mold support board 22, and an upper side of the mold support board 22. And a second mold 30 that is a female mold supported on the lower surface of the mold support board 28.
[0018]
The pair of upper and lower molds 24 and 30 respectively have cavity surfaces 32 and 34 that correspond to the desired shape of the multilayer molded article 10 and face each other. The cavity surfaces 32 and 34 form cavities that generally match the outer shape of the desired multilayer molded article 10 when the upper and lower molds 24 and 30 are closed. The material of the molds 24 and 30 is not particularly limited, and is appropriately selected from various metal materials, resins, ceramics, and the like depending on a required shape, surface state, and molding conditions.
[0019]
The cavity surface 32 of the lower mold 24 is provided with a main resin supply gate 36 for supplying the molten resin into the cavity. The resin supply gate 36 is a resin supply passage 38 formed in the mold 24. Communicated with. The resin supply passage 38 is connected to an injection nozzle of an injection device (not shown) that can melt the thermoplastic resin and inject a desired amount. The position and number of the resin supply gates 36 are appropriately changed depending on the shape and size of the multilayer molded product 10 to be manufactured. If the molten resin cannot be distributed in the cavity by using only the main resin supply gate 10, an auxiliary resin supply gate (not shown) may be provided at other parts of the cavity surface 32 as appropriate. Good.
[0020]
A protrusion 40 is formed on the cavity surface 34 of the upper mold 30. The protrusion 40 is provided at a position corresponding to the edge of the skin material 12 in the multilayer molded product 10 disposed between the molds 24 and 30 during molding. The protrusion 40 defines a skin material arrangement portion where the skin material 12 is arranged during molding between the edge of the cavity surface 34 of the mold on the outside thereof. It is desirable that the height of the protrusion 40 is larger than the thickness of the skin material 12 to be used when it is compressed. Further, although depending on the thickness of the base material 14 of the multilayer molded article 10, it is preferable to form the recess 42 in the portion of the lower mold cavity surface 32 facing the protrusion 40. This is to prevent the thickness of the base material 14 from being reduced only by the portion of the ridge 40, and, as will be described later, to make the cavity clearance smaller than the height of the ridge 40 during the supply of the molten resin.
[0021]
Further, a clamp device 44 for clamping the skin material 12 is disposed outside the lower mold 24. The clamp device 44 includes a clamp frame 46. As understood from the two-dot chain line in FIG. 2, the clamp frame 46 protrudes from the cavity surfaces 32 and 34 of the molds 24 and 30 when the skin material 12 is supplied between the molds 24 and 30. Is sandwiched between the lower surface of the outer peripheral portion of the upper mold 30. In the illustrated embodiment, the clamp frame 46 is a continuous U-shaped body as shown in FIG. 2, but may have other forms, for example, a plurality of divided forms. The clamp frame 46 can be moved up and down by a driving device 48 such as an air cylinder.
[0022]
Next, a method for manufacturing the multilayer molded article 10 of FIG. 6 using the molding apparatus 20 described above will be described with reference to FIGS.
[0023]
First, a thermoplastic resin to be the base material 14 of the multilayer molded article 10 and the skin material 12 are prepared.
[0024]
The thermoplastic resin is put into an injection device (not shown) and is in a molten state in advance.
[0025]
On the other hand, as shown in FIG. 3A, the skin material 12 is supplied between the molds 24 and 30 in an open state and arranged at a predetermined position on the cavity surface 32 of the lower mold 24. In this state, as shown by a two-dot chain line in FIG. 2, a part of the outer peripheral portion of the skin material 12 protrudes from the mold 24, and this portion is placed on the clamp frame 46 and appropriate fixing means such as a pin (illustrated). No) is positioned and fixed to the clamp frame 46. At the time of positioning, a part of the edge 50 of the skin material 12 is in a state of being in contact with the ridge 40 or in a state of being located in the recess 42. As for the degree, it is preferable that the edge 50 of the skin material 12 is not detached from the ridge 40 in the mold clamping stage to be described later. However, when the mold clamping is completed, the edge 50 of the skin material 12 is removed from the ridge 40. It is more preferable to set it to the extent which corresponds to the front-end | tip part.
[0026]
Next, the drive device 26 is controlled to move the upper mold support plate 28 and the mold 30 downward, and the outer peripheral portion of the skin material 12 between the lower surface of the outer peripheral portion of the upper mold 30 and the clamp frame 46. Pinch. And the drive apparatus 48 of the clamp apparatus 44 is controlled, and the clamp frame 46 is lowered | hung with the metal mold | die 30 with the state which clamped the skin material 12 maintained.
[0027]
When the mold is lowered in this way and stopped at a predetermined position, a cavity 52 having a predetermined size is formed between the molds 24 and 30. If the cavity is formed between the molds 24 and 30, when the molten resin 54 is injected from the injection device, the molten resin 54 is supplied from the resin supply passage 38 of the mold 24 through the resin supply gate 36 into the cavity 52. ((B) of FIG. 3). At this time, the molten resin 50 supplied from the resin supply gate 36 gradually spreads outward from the space in the cavity 52 where the skin material 12 is not disposed, and eventually reaches the protrusion 40 and the recess 42. As shown in FIG. 4, the molten resin 54 flows outward along the inner surface of the recess 42 after the flow direction is changed downward by the protrusion 40. As a result, the molten resin 54 is preferentially supplied to the back surface side of the skin material 12, and the edge 50 of the skin material 12 disposed adjacent to the protrusion 40 or the recess 42 is pushed to design the surface of the skin material 12. It does not enter the side (the side facing the mold 30).
[0028]
When the molten resin 54 is supplied, it is preferable to set the position so that the cavity clearance between the molds 24 and 30 is smaller than the height of the protrusion 40. That is, it is preferable that the tip of the ridge 40 is positioned so as to slightly enter the recess 42. If the molten resin is supplied in a state in which the cavity clearance is larger than the height of the protrusion 40, the protrusion 40 does not function as a flow deflection function or a weir of the molten resin 54, and the design surface side of the skin material 12 This is because the molten resin 54 may enter into the product, resulting in poor appearance of the product.
[0029]
Next, the mold 30 is further lowered to perform mold clamping, and the molten resin supplied into the cavity 52 is cooled and solidified ((c) in FIG. 3). The timing of mold clamping may be either during the supply of the molten resin 54 or after the supply is completed. However, when the mold is clamped after the supply is completed, the mold clamping should be started immediately after the supply of the molten resin 54 is completed. Is preferred.
[0030]
When a predetermined cooling / solidification time has elapsed, the mold support board 28 and the mold 30 are raised, and the base material 14 formed by solidifying the molten resin 52 and the skin material 12 are bonded together. Take out the goods. Thereafter, processing such as excision of the protruding portion of the skin material 12 and winding on the back surface of the product is performed, and the multilayer molded product 10 as a product shown in FIG. 6 is completed. As described above, since the molten material does not flow to the design surface side of the skin material 12, the appearance of the product is extremely good.
[0031]
In addition, as a thermoplastic resin, resin normally used by compression molding, injection molding, extrusion molding, etc. can be applied as it is. For example, general thermoplastic resins such as polypropylene, polyethylene, acrylonitrile-styrene-butadiene block copolymers, polyamides such as polystyrene and nylon, polyvinyl chloride, polycarbonate, acrylic resins, styrene-butadiene block copolymers, EPM and EPDM Examples thereof include thermoplastic elastomers such as these, mixtures thereof, and polymer alloys using these, and these may be non-foaming or foaming.
[0032]
Further, these thermoplastic resins may contain fillers such as glass fibers that are usually used as required, various inorganic or organic fillers, and of course various pigments, lubricants that are usually used, Additives such as antistatic agents and stabilizers may be blended.
[0033]
As the skin material, any material that does not melt even when in contact with a thermoplastic resin in a molten state and can be heat-sealed to the thermoplastic resin, for example, a woven or knitted fabric such as a moquette or to limit, a needle Nonwoven fabrics such as punched carpets, metal foils, thermoplastic resins and thermoplastic elastomer sheets or films can be appropriately selected according to the thermoplastic resin of the substrate.
[0034]
These skin materials may be laminated skin materials having two layers or three or more layers in which foam layers and backing layers are appropriately laminated as required, and skin materials in which foam layers are laminated are particularly preferably applied. These laminated skin materials can be bonded to the base material thermoplastic resin, or the surface skin material can be impregnated with molten thermoplastic resin to adhere to the base material thermoplastic resin. It is necessary to be something.
[0035]
As the foam layer in this case, polyolefin-based foams such as polypropylene and polyethylene, polypinyl chloride foam, and soft or semi-rigid polyurethane foam can be used.
[0036]
As the backing layer, a nonwoven fabric or a synthetic resin sheet or film can be used. As the fibers constituting the nonwoven fabric, natural fibers such as cotton, wool, silk and hemp, or synthetic resins such as polyamide, polyester, and nylon can be used. What was made into the nonwoven fabric is used. Examples thereof include nonwoven fabrics such as a needle punch type, a thermal bond type, a spun bond type, a melt blow type and a spun lace type. Examples of the sheet or film made of a synthetic resin include a thermoplastic resin such as polypropylene and polybutylene, and a sheet or film of a polyolefin-based thermoplastic elastomer, and a material that is fusible with the base thermoplastic resin is used.
[0037]
As mentioned above, although preferred embodiment of this invention was described in detail, it cannot be overemphasized that this invention is not limited to the said embodiment.
[0038]
For example, a foamable thermoplastic resin can be used for the base material 14. In order to foam the base material 14, after the surface material 12 is positioned and the cavity 52 is formed between the molds 24 and 30 in the same manner as the procedure of (a) to (c) in FIG. A molten resin 54 containing a foaming material is supplied from the resin supply gate 36 and the mold is clamped. First, primary cooling is performed in the mold clamping state shown in FIG. 3C, and a skin layer is formed on the molten resin 54 in contact with the cavity surface 34 of the mold 30. The primary cooling time at this time is usually about 0.1 to 5 seconds, although it varies depending on various conditions such as mold temperature, molten resin temperature and characteristics. When the primary cooling for a predetermined time is completed, as shown in FIG. 3D, when the mold 30 is moved upward and the cavity 52 is enlarged, it is trapped in the unsolidified portion of the supplied molten resin 54. The foaming gas generated by the decomposition of the foaming agent that has been expanded expands, increasing the thickness while forming a foamed layer in the thickness direction of the molded body. When the cavity clearance reaches the product thickness after foaming, the cavity expanding operation, that is, the rise of the mold 30 is stopped, and this state is maintained and the molten resin 54 is cooled and solidified.
[0039]
As the foaming agent used in this method, a known chemical foaming agent used when producing a foam of a thermoplastic resin as a base can be used. Specifically, inorganic foaming agents such as sodium bicarbonate, ammonium bicarbonate and ammonium carbonate, nitroso compounds such as N, N′-dinitrosopentamethylenetetramine, azodicarbonamide, azo such as azopisisobutyronitrile, etc. A blowing agent such as a compound, a sulfonyl hydrazide such as benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonyl hydrazide, or p-toluenesulfonyl semicarbazide can be used. It is a preferred embodiment to add salicylic acid, urea and a foaming aid containing these as required. Of course, the type of foaming agent is selected in consideration of the melting temperature of the thermoplastic resin to be used, the target foaming ratio, and the like. The amount added is adjusted in consideration of the strength, density and the like of the target molded product, but is generally 0.1 to 5 parts by weight with respect to 100 parts by weight of the resin. Further, in addition to the chemical foaming agent, liquid or gaseous carbon dioxide and / or nitrogen or the like may be directly injected into the molten resin for foaming.
[0040]
Moreover, in the said embodiment, although the shaping | molding apparatus 20 uses what is called a vertical type whose mold clamping direction is an up-down direction, this invention is a horizontal direction, ie, at least one of a metal mold | die is a horizontal direction. It is also applicable to a horizontal molding apparatus that is movable.
[0041]
Further, in the above embodiment, the skin material 12 is not previously processed, but the skin material 12 is preheated before being supplied between the molds 24 and 30, or preshaped. May be. In particular, when preliminary shaping is performed, there is an advantage that accurate positioning can be performed.
[0042]
From the viewpoint of accurate positioning of the skin material, a suction passage 56 connected to a vacuum pump is formed in the mold as indicated by the dotted line in FIG. 1, and the skin material 12 is adsorbed to the cavity surface 34 of the mold 30. Is also effective.
[0043]
Furthermore, the position where the skin material 12 is disposed is not limited to the edge portion of the base material 14. For example, even in the central portion, there may be a case where the skin material needs to be disposed in a part away from the main resin supply gate 36 in the molds 24 and 30. In such a case, an annular protrusion may be provided so as to surround the skin material arrangement portion of the mold, and the edge of the skin material may be disposed so as to contact the annular protrusion over the entire circumference.
[0044]
Further, the mold clamping may be performed before the supply of the molten resin is completed.
[0045]
【The invention's effect】
As described above, according to the production method of the present invention, it is possible to efficiently produce a multilayer molded article having good positioning properties and appearance of the skin material. Moreover, since the position of the resin supply gate may be a general position, there is an effect that the cost for manufacturing the mold can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a molding apparatus that can be used in a method for producing a multilayer molded article according to the present invention.
FIG. 2 is a schematic arrow view along the line II-II in FIG. 1;
FIGS. 3A to 3D are schematic explanatory views showing a method for producing a multilayer molded article in stages, and FIG. 3D is a diagram in the case of producing a multilayer molded article having a foamable substrate. is there.
FIG. 4 is an enlarged view of a mold showing a flow state of a molten resin.
FIG. 5 is a schematic explanatory view illustrating a conventional method for producing a multilayer molded article.
FIG. 6 is a schematic view showing an example of a multilayer molded article produced by the method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 ... Molding apparatus, 24 ... 1st metal mold | die, 30 ... 2nd metal mold | die, 36 ... Main resin supply gate, 40 ... Projection, 42 ... Recessed part, 44 ... Clamp apparatus, 50 ... Edge, 52 ... Cavity 54 ... Molten resin, 56 ... Suction passage.

Claims (5)

A method for producing a multilayer molded article comprising a base material made of a thermoplastic resin and a skin material laminated and integrated on at least a part of the surface of the base material and having a foam layer ,
A first mold having a main resin supply gate for supplying a molten thermoplastic resin, and a recess provided at a position away from the resin supply gate, and the first mold A second mold that is openable and closable and forms a cavity with the first mold when closed, and is a skin material in a multilayer molded product after manufacture is completed at a position facing the recess. Preparing the second mold having a protrusion provided at a position corresponding to the edge of
A skin material is disposed at a predetermined position between the first mold and the second mold in an open state, away from the portion facing the main resin supply gate, beyond the ridge, A portion of the edge of the skin material is in contact with the ridge when the space between the first mold and the second mold is closed;
A molten thermoplastic resin is supplied from the main resin supply gate with a gap between the first mold and the second mold being narrowed, and the mold is clamped during or after the completion of the supply of the thermoplastic resin. A method for producing a multilayer molded article.   When the molten thermoplastic resin is supplied from the main resin supply gate, the cavity clearance between the first mold and the second mold is set to be smaller than the height of the protrusion. The method for producing a multilayer molded article according to claim 1, wherein   The method for producing a multilayer molded article according to claim 1 or 2, wherein the skin material is arranged at the predetermined position so that a part of an edge of the skin material is in contact with the protrusion or located in the recess. .   The method for producing a multilayer molded article according to any one of claims 1 to 3, wherein a pre-shaped skin material is used as the skin material.   The method for producing a multilayer molded article according to any one of claims 1 to 4, wherein the skin material is adsorbed and disposed on the cavity surface of the second mold by suction.

Images