JP2013119196A - In-mold molding method and resin molded product molded by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-mold molding method by which the molding of a resin molded product and painting on the surface are simultaneously carried out, a partition line formed on the surface of the resin molded product is controlled to only one or zero and the wrinkle produced on the surface of the finished resin molded product is minimized to finely decorate the surface.SOLUTION: A transfer sheet (10) is sucked on a cavity molding surface (32) by arranging the cylindrically rounded transfer sheet (10) in the mold (34) forming a cavity (42) having an opening (45) and evacuating a portion between the transfer sheet 10 and the cavity molding surface 32 through a suction passage (44) and after that, the opening (45) is closed with a core mold (38) to seal the cavity (42) and the molten resin (Y) is injected into the transfer sheet (10).

Description

  The present invention relates to an in-mold molding method applicable to general interior / exterior material products of complex shapes used for automobiles, airplanes, heavy machinery, cruisers, houses, furniture, home appliances, and the like, and a resin molded article formed by the method. And about.

  A decorative / transfer sheet (PET original fabric; hereinafter simply referred to as “transfer sheet”) on which a design pattern is printed is sandwiched between molds of an injection molding machine, and then molten resin (plastic) is inserted into the mold. In-mold molding, in which a printed design pattern is transferred to a resin by the heat of a molten resin or the like, is widely used for decorating resin molded products such as automobile parts and household appliance parts.

  In general, in addition to in-mold molding, there are methods such as painting, printing, vacuum transfer, or hydraulic transfer in addition to in-mold molding, but in-mold molding can lead to post-molding and secondary processing. Since there is no yield reduction due to quality defects at the time, there is an advantage that the lead time is shortened and the yield of the total process can be controlled. In addition, according to in-mold molding, since hard coating is possible at the time of molding, in recent years, cases employed in the manufacture of mobile phone casings are increasing.

  As such an in-mold molding method, for example, a technique for transferring a predetermined pattern from a transfer sheet at a time onto the entire peripheral surface of a columnar resin molded product is disclosed in Japanese Patent Laid-Open No. 4-208423 (Patent Document 1). Yes.

  According to the technique disclosed in Patent Document 1, when a pair of molds are closed to form a cavity, a pair of transfer sheets supplied so that the transfer surfaces face each other are arranged between both molds. . As a result, when the mold is closed, the transfer sheet is sandwiched between and closely adhered to each other by a pair of opposite edges of the mold, and a cylindrical transfer sheet is formed in the cavity. After that, by injecting molten resin into this cylindrical transfer sheet, a resin molded product that matches the cavity shape is molded, and at the same time, the design from the transfer sheet is applied to the entire peripheral surface of the resin molded product. Can be transferred.

JP-A-4-208423

  However, in the technique disclosed in Patent Document 1, two joints (= hereinafter referred to as “partition lines”) in which a pair of transfer sheets are in close contact with each other by being sandwiched between molds always occur. For this reason, two partition lines will also be generated in the pattern transferred to the peripheral surface of the resin molded product. In addition, since the portion sandwiched between the molds remains as burrs, the cut marks of the burrs appear on the appearance, causing the aesthetics of the resin molded product to be impaired.

  In addition, if the shape of the cavity forming surface is complicated in order to form a more complicated shaped resin molded product, as long as it is a simple cylindrical resin molded product as in Patent Document 1. Because it is difficult to bring the transfer sheet into precise contact with the cavity forming surface, the transfer sheet may be wrinkled on the surface of the resin molded product, or the transfer sheet may be torn due to high temperature and pressure during injection. As a result, it was impossible to mold a resin molded product having a complicated surface shape.

  The present invention has been developed in view of such problems of the prior art. Therefore, the main problem of the present invention is that the molding of the resin molded product and the painting on the surface thereof can be performed simultaneously, and the partition line generated on the surface of the resin molded product can be reduced to one or zero. Furthermore, another object of the present invention is to provide an in-mold molding method capable of minimizing wrinkles generated on the surface of a finished resin molded product and decorating it cleanly, and a resin molded product formed by the method.

In order to achieve the above object, in the present invention, the in-mold forming method is configured as follows. That is,
The end opening 10c of the transfer sheet 10 coincides with the opening 45 between the cavity forming surfaces 32 of the mold 34 forming the cavity 42 having the opening 45 in at least one place. Arranged so that
The pressure between the transfer sheet 10 and the cavity forming surface 32 is reduced through the suction path 44 formed in the mold 34 and opened to the cavity forming surface 32, and the transfer sheet 10 is adsorbed to the cavity forming surface 32. Let
While the transfer sheet 10 is adsorbed on the cavity forming surface 32, the opening 45 is closed by the core mold 38 to seal the cavity 42, and then the injecting molten resin Y into the transfer sheet 10 is performed. This is a molding method.

Moreover, it is preferable to add the following structure to this invention. That is,
The mold 34 includes an inner mold 35 and an outer mold 36 that covers the inner mold 35, and is rounded and cylindrically formed between the cavity forming surfaces 32 provided on the inner mold 35. The transfer sheet 10 is disposed such that the end opening 10c of the transfer sheet 10 coincides with the opening 45 of the cavity 42,
The pressure between the transfer sheet 10 and the cavity forming surface 32 is reduced through the suction path 44 that is formed in the inner mold 35 and opens in the cavity forming surface 32, and the transfer sheet 10 is moved to the cavity forming surface 32. Adsorb to
While the transfer sheet 10 is adsorbed to the cavity forming surface 32, the outer mold 36 is placed on the inner mold 35,
The core mold 38 is advanced toward the inner mold 35 to close the opening 45 of the cavity 42 to seal the cavity 42, and then the molten resin Y is injected into the transfer sheet 10.

  According to the present invention, between the transfer sheet 10 and the cavity forming surface 32, the transfer sheet 10 formed into a cylindrical shape by joining both edge portions 10a and 10b of the rolled transfer sheet 10 butting each other is decompressed. In this way, it is adsorbed on the cavity forming surface 32. Thereafter, since the molten resin Y is injected inside the transfer sheet 10, at most one partition line can be formed on the pattern formed on the surface of the finished resin molded product Z. . Further, since the transfer sheet 10 is sucked to the cavity forming surface 32 under reduced pressure before the molten resin Y is injected, the wrinkles of the transfer sheet 10 can be extended by the reduced pressure suction, and the finished resin molded product Z It is possible to minimize wrinkles generated on the surface.

  Of course, when both edge portions 10a and 10b butting each other in the rolled transfer sheet 10 are bonded by a known seamless process, the partition line formed on the surface of the resin molded product Z becomes zero. Further, even if seamless processing is not performed, one partition line can be made almost inconspicuous by adjusting the partition lines so that the symbols are continuous without a sense of incongruity.

Moreover, it is preferable to add the following structure to this invention. That is,
After disposing the transfer sheet 10 between the cavity forming surfaces 32, until the transfer sheet 10 is adsorbed to the cavity forming surface 32 under reduced pressure,
The balloon 40 that expands and contracts when the pressurized fluid L is supplied and discharged is inserted into the transfer sheet 10 through the opening 45 in a contracted state, and the pressurized fluid L is supplied to expand the balloon 40. By pressing the transfer sheet 10 against the cavity forming surface 32 with the balloon 40,
After the transfer sheet 10 is adsorbed to the cavity forming surface 32 under reduced pressure and before the cavity 42 is sealed,
The balloon 40 deflated by discharging the pressurized fluid L is taken out from the opening 45.

  According to this, the balloon 40 is inflated in the transfer sheet 10 in the cavity 42, and the transfer sheet 10 is pressed against the cavity forming surface 32 with the inflated balloon 40, so that the cavity formed in the die 34 is formed. Even if the shape of the forming surface 32 is complicated, the transfer sheet 10 can be accurately aligned with and closely contacted with the shape of the cavity forming surface 32 by the pressing force generated by the expansion of the balloon 40. Even the molded product Z can be decorated more beautifully.

  Throughout this specification, the cylindrical transfer sheet 10 may be inserted between the cavity forming surfaces 32 of the mold 34 when the mold is opened, or after the mold is closed. There may be. Further, the “tubular shape” of the transfer sheet 10 does not mean only a cylindrical shape, but a shape corresponding to the surface shape of the resin molded product Z defined by the cavity forming surface 32 (for example, bottomed) (Cylindrical shape). That is, the outer shape of the “cylindrical transfer sheet 10” is not particularly limited as long as it has an end opening 10c into which the balloon 40 is inserted.

It is preferable to add the following configuration to the present invention (see FIG. 4). That is,
After the transfer sheet 10 is disposed between the cavity forming surfaces 32 of the mold 34 or the inner mold 35 and before the balloon 40 is inserted into the transfer sheet 10, the transfer sheet 10 is inserted into the mold 34 or It is adsorbed on one cavity forming surface 32 of the inner mold 35. By doing so, the transfer sheet 10 can be easily positioned with respect to the cavity forming surface 32.

The following configuration is preferably added to the present invention. That is,
The dynamic friction coefficient of the surface of the balloon 40 is set to 4.0 or less.

  When the balloon 40 is inflated and presses the transfer sheet 10 against the cavity forming surface 32, the surface of the balloon 40 comes into contact with and rubs against the surface of the opposite transfer sheet 10 (surface that adheres to the resin molded product Z). You will slide on the surface of the lever. At this time, if the coefficient of dynamic friction (= MIU) on the surface of the balloon 40 is too large, the surface of the balloon 40 is caught on the surface of the transfer sheet 10, and the transfer sheet 10 is wrinkled or severe. 10 may be torn. In this regard, the above-described problem can be solved by setting the dynamic friction coefficient of the surface of the balloon 40 to 4.0 or less.

Moreover, it is preferable to add the following structure to this invention. That is,
The transfer sheet 10 includes a resin base sheet 12 that is highly stretchable at room temperature, and a pattern ink layer 14 that is formed on the surface of the base sheet 12 and is highly stretchable at room temperature.
The base sheet 12 has an elongation rate of 200% or more at normal temperature and an elastic recovery rate of 40% or less at the time of 60% elongation, and the resin constituting the base sheet 12 is: The melting point is 120 ° C. or higher.

  By forming the transfer sheet 10 with a resin base sheet 12 having high stretchability at normal temperature and a pattern ink layer 14 formed on the surface of the base sheet 12 and also having high stretchability at normal temperature, Even when the shape of the cavity forming surface 32 is complicated and deep drawing when the transfer sheet 10 is adsorbed to the cavity forming surface 32 and further pressed against the cavity forming surface 32 by the balloon 40, the transfer sheet In the portion where the cavity forming surface 32 is widened, the portion 10 expands correspondingly, and in the portion where the cavity forming surface 32 is narrowed, it shrinks correspondingly as well, and closely adheres to the entire surface along the shape of the cavity forming surface 32. By injecting the molten resin Y with the transfer sheet 10 in close contact, the pattern drawn on the pattern ink layer 14 of the transfer sheet 10 is directly drawn on the surface of the resin molded product Z without deformation.

  As described above, even if the base sheet 12 and the design ink layer 14 constituting the transfer sheet 10 are inferior in heat resistance, a material having high elasticity at room temperature can be used as described above. In addition, the transfer sheet 10 is attracted to the cavity forming surface 32 by reducing the pressure between at least the transfer sheet 10 and the cavity forming surface 32. When the molten resin Y is injected into the transfer sheet 10 in this adsorbed state, the heat of the injected molten resin Y is immediately conducted to the mold through the transfer sheet 10, so that the injection pressure of the molten resin Y or the molten resin Y It is possible to avoid the transfer sheet from becoming hot as in the conventional in-mold molding in which the transfer sheet is stretched using heat.

  According to the present invention, the molding of the resin molded product and the painting on the surface thereof can be performed at the same time, the partition line generated on the surface of the resin molded product can be one or zero, It was possible to provide an in-mold molding method capable of molding a resin molded product having almost no wrinkles on the surface and a resin molded product formed by the method.

It is sectional drawing ((a) cross section, (b) longitudinal cross section) of the metal mold apparatus in the case of using an inner metal mold | die and an outer metal mold | die used for this invention. It is sectional drawing of the transfer sheet of this invention. It is sectional drawing of the other Example concerning the transfer sheet of this invention. It is sectional drawing ((a) cross section, (b) longitudinal cross section) which shows the procedure of injection molding. It is sectional drawing ((a) cross section, (b) longitudinal cross section) which shows the procedure of injection molding. It is sectional drawing ((a) cross section, (b) longitudinal cross section) which shows the procedure of injection molding. It is sectional drawing ((a) cross section, (b) longitudinal cross section) which shows the procedure of injection molding. It is sectional drawing ((a) cross section, (b) longitudinal cross section) which shows the procedure of injection molding. It is sectional drawing ((a) cross section, (b) longitudinal cross section) which shows the procedure of injection molding. It is sectional drawing ((a) cross section, (b) longitudinal cross section) which shows the procedure of injection molding. It is sectional drawing ((a) cross section, (b) longitudinal cross section) which shows the procedure of injection molding. It is a longitudinal cross-sectional view of the metal mold | die apparatus in the case of using 1 metal mold | die used for this invention. It is a longitudinal cross-sectional view before injection of the mold apparatus shown in FIG.

  Embodiments to which the present invention is applied will be described below with reference to the drawings. First, after describing the configuration of the transfer sheet 10 used for in-mold molding according to the present invention, the mold apparatus 30 of an injection molding machine that performs in-mold molding will be described, and then using this transfer sheet 10. A procedure for performing in-mold molding will be described. The mold apparatus 30 includes an inner mold 35, an outer mold 36, and a core mold 38 (this is a separation mold apparatus 30; see FIGS. 1 to 11), and an inner mold apparatus 30. It can be considered that the mold 35 and the core mold 38 are integrated with the mold 35 and the outer mold 36 (this is an integrated mold apparatus 30; see FIGS. 12 and 13). The former will be described with reference to the drawings, and the latter will be briefly described with reference to the former.

  As shown in FIG. 2, the transfer sheet 10 according to the present invention includes a base sheet 12, a design ink layer 14, and a primer layer 16 provided as necessary.

  The base material sheet 12 is made of a material having an elongation rate of 200% or more at normal temperature and an elastic recovery rate of 40% or less at the time of 60% elongation. Examples of such a material include a soft polyolefin film, a urethane elastomer film, or a vinyl chloride film that has high stretchability even at room temperature.

  Further, as will be described later, in the in-mold molding of this embodiment using this transfer sheet 10, the molten resin Y is injected after the transfer sheet 10 is adsorbed on the cavity forming surface 32 of the mold 34. Therefore, since the heat of the molten resin Y is immediately conducted to the mold 34 through the transfer sheet 10, the transfer sheet 10 that has received the injection of the molten resin Y does not become as hot as before. Thereby, even if it receives the heat from the molten resin Y at the time of injection, the transfer sheet 10 can be prevented from being melted or thermally deteriorated. Therefore, the resin constituting the base sheet 12 has the above-mentioned stretchability and bending resistance. A material having a low melting point (having a melting point of about 120 ° C.) while having excellent tear resistance can be used.

  For the pattern ink layer 14 on which a desired pattern (including characters) is drawn, a thermoplastic polyurethane resin, a thermoplastic acrylic resin, or a vinyl chloride / vinyl acetate copolymer resin alone or a polymer blend is preferably used. However, it is not limited to these.

  Conventionally, the ink used for in-mold molding must be selected to have a high cohesive force and low stretchability at room temperature in order to withstand high temperatures caused by heat received from the molten resin Y during injection. For this reason, the pattern ink layer used in the conventional method has to be stretched by preheating or heating with the heat of the molten resin Y at the time of injection.

  However, in this embodiment, since the transfer sheet 10 including the design ink layer 14 does not become as high as the conventional one as described above, the design ink layer 14 is also at room temperature, similarly to the base sheet 12. A material having high elasticity (but slightly inferior in heat resistance) can be used. However, the design ink layer 14 having heat resistance that can withstand a certain temperature rise (130 to 150 ° C.) due to heat at the time of injection is required.

  Any known printing method such as offset printing, gravure printing, screen printing, or the like may be used as a method for printing the pattern on the pattern ink layer 14. Throughout the present specification, “design” is a concept that includes not only patterns but also characters and symbols.

  The primer layer 16 is an olefin-based primer, and is provided when an olefin-based crystalline polymer typified by PP (polypropylene) is used as the material of the resin molded product Z. Further, when an amorphous material typified by ABS resin is used as the material of the resin molded product Z, it is not necessary to provide the primer layer 16.

  As shown in FIG. 3, a release layer 18 may be provided between the base sheet 12 and the design ink layer 14. When the release layer 18 is not provided, the resin molded product Z is in a state where the surface of the base sheet 12 is laminated. When the release layer 18 is provided, the base sheet 12 is subjected to design ink after injection molding. By peeling from the layer 14, the design ink layer 14 (and the primer layer 16) is transferred to the surface of the resin molded product Z.

  As shown in FIG. 1, a mold apparatus 30 of an injection molding machine that performs in-mold molding using such a transfer sheet 10 is roughly a pair of inner molds (female molds) 35 and a pair of outer molds. 36, a pair of core type (male type) 38, and a balloon 40 used as necessary.

  The pair of inner dies 35 has a cavity forming surface 32 having a predetermined shape on the surfaces facing each other, and a cavity 42 is formed inside by closing both dies 34 (FIG. 5). (See (a)). In the in-mold molding of this embodiment, since it is necessary to insert the balloon 40 into the cavity 42 as will be described later, at least one end (both ends in this embodiment) of the cavity 42 with the mold 34 closed. There is an opening 45 (see FIG. 5B).

  Further, the inner mold 35 is formed with a suction path 44 having one end opened in the cavity forming surface 32 and the other end connected to a suction pump or the like (not shown). The suction passage 44 may be a plurality of (or even one) through-holes as shown in the figure, or a porous metal is used for the inner mold 35 and countless fine holes are used as the suction passage 44. May be. When a porous metal is used for the inner mold 35, the outer mold 36 is made of a dense metal and the suction path 44a is provided. In the case of the through hole type suction path 44, the suction path 44 a provided in the outer mold 36 communicates with the suction path 44 of the inner mold 35. The number of inner molds 35 is not limited to two, and the cavity 42 may be formed by combining three or more inner molds 35. Further, the opening 45 may be provided only at one of the end portions.

  The pair of core molds (male molds) 38 is a mold that closes the openings 45 at both ends of the cavity 42, a main body portion 47 having a mold closing surface 46 that closes the opening 45, and a diameter smaller than that of the main body portion 47 from the center. Projected and inserted into the cavity 42 when molding a cylindrical resin molded product Z (or a cylindrical shape having a partition “node” at the inner central portion), etc., the inner shape of the resin molded product Z is It is comprised with the convex part 48 to prescribe | regulate. Of course, when the solid resin molded product Z is molded, the convex portion 48 is not necessary. In this embodiment, the core mold 38 is attached to the outer mold 36 so as to be able to advance and retract. However, the pair of core molds 38 may be separated and independent from the outer mold 36. Further, an L-shaped injection path 59 having one end opened in the cavity 42 and the other end opened in the mold closing surface 46 is formed in the main body 47 of one core mold 38.

  The pair of outer molds 36 are formed with a mold receiving space 50 formed in a concave shape for receiving the inner mold 35 in a state of being covered with the inner mold 35 and closed. That is, a space forming surface 52 that forms the mold housing space 50 is formed on the surfaces of the outer molds 36 facing each other. Further, when the outer mold 36 is clamped, one end of the outer mold 36 communicates with the injection path 59 of the main body portion 47 of the core mold 38 at a position disengaged from the inner mold 35, and the other end is connected to a molten resin supply device (not shown). The molten resin injection path 58 is formed at the end of one (right side) outer mold 36.

  In this embodiment, the molten resin Y supplied through the molten resin injection path 58 passes through the injection path 59 formed in the main body portion 47 of the lower core mold 38 in the drawing and is melted on the mold closing surface 46. Since the resin injection hole 60 is injected into the cavity 42, the injection path 59 and the molten resin injection path 58 communicate with each other during mold clamping, and the injection path 59 is adsorbed to the cavity forming surface 32 of the inner mold 35. The transfer sheet 10 is opened inside.

  Of course, the injection position of the molten resin Y is not limited to this, and an optimal injection position can be selected according to the shape of the resin molded product Z, but the injection pressure of the molten resin Y is determined by the transfer sheet 10. In order to prevent the transfer sheet 10 from being damaged by acting directly on the sheet, it is preferable to inject along the transfer sheet 10 from one end of the cavity 42 toward the other end as in this embodiment.

  The balloon 40 used as needed includes a main body portion 54 that expands and contracts by supplying and discharging a pressurized fluid L that is a gas such as compressed air and a liquid such as hydraulic oil and water. The coupler 56 is configured to supply and discharge the pressurized fluid L. The material of the main body 54 is preferably a material that has high durability and airtightness against expansion and contraction, and has a flexibility that allows the main body portion 54 to closely adhere to the shape of the cavity forming surface 32 of the inner mold 35 during expansion. As will be described later, when the balloon 40 is inflated, the surface of the balloon 40 comes into contact with and rubs against the primer layer 16 of the transfer sheet 10 (the design ink layer 14 when the primer layer 16 is not provided). The surface material of the balloon 40 is preferably a material in which the ink of the design ink layer 14 does not easily transfer to the surface of the balloon 40. In the present embodiment, the material of the main body portion 54 is a material in which a knit fabric is applied to the outer surface of chloroprene rubber used for a fabric such as a wet suit to increase the strength.

  Further, it is preferable to set the dynamic friction coefficient (= MIU) of the surface of the balloon 40 (knitted fabric in this embodiment) to 4.0 or less. When the balloon 40 expands and presses the transfer sheet 10 against the cavity forming surface 32, the surface of the balloon 40 is the surface of the opposing transfer sheet 10 (in this embodiment, the primer layer 16 that adheres to the surface of the resin molded product Z). ) And slide on this surface in a rubbing manner. At this time, if the coefficient of dynamic friction (= MIU) on the surface of the balloon 40 is too large, the surface of the balloon 40 is caught on the surface of the transfer sheet 10, and the transfer sheet 10 is wrinkled or severe. 10 may be torn. In this respect, the above-described problems can be solved by setting the dynamic friction coefficient of the balloon surface to 4.0 or less. In addition, it is preferable to set the MMD (friction coefficient variation: average deviation) on the surface of the balloon 40 to 0.75 or less. The smaller the MMD value, the smaller the MIU variation and the smoother the surface.

  In addition, in order to make the dynamic friction coefficient of the surface of the balloon 40 4.0 or less, a material having a small MIU on the surface may be selected, and the surface has a fine center line average roughness of about several microns to several tens of microns. The frictional force may be reduced by forming a rough surface and preventing adhesion between materials. The method of forming irregularities is particularly effective for adhesive PVC materials and urethane materials. Further, as a specific example of the unevenness formation, it is conceivable to add a matting agent such as silica fine particles to the surface of the balloon 40 or to physically emboss the surface.

  Further, a cooling water supply pipe 62 and a cooling water discharge pipe 64 are connected to the inner mold 35, the core mold 38, and the outer mold 36, respectively, in order to prevent seizure due to heat from the molten resin Y. The cooling water CW is allowed to flow (in FIGS. 4 to 11, the cooling water supply pipe 62 and the cooling water discharge pipe 64 are not shown in order to avoid complication of the drawings). .

  Next, a procedure for performing in-mold molding of a resin molded product Z having a complicated shape (cylindrical resin molded product Z having a partition at the inner center) using the transfer sheet 10 and the mold apparatus 30 described above. explain.

(Step 1)
First, a transfer sheet 10 that is rolled up into a cylindrical shape is prepared (see FIG. 4B). When forming a cylindrical shape, both edges 10a and 10b of the transfer sheet 10 are rolled and abutted against each other so that the base sheet 12 of the transfer sheet 10 is on the outside and the primer layer 16 (or the design ink layer 14) is on the inside. And heat seal the overlap. Of course, the overlapping portion may be bonded with an adhesive or the like, or the both edge portions 10a and 10b may be bonded to each other without being overlapped. In addition, it is preferable to set the positions of the pattern and the joint so that the pattern of the pattern ink layer 14 is naturally continuous at the position of the joint because the partition line in the finished resin molded product Z can be made inconspicuous.

  Next, after the transfer sheet 10 is inserted between the inner dies 35 with the pair of inner dies 35 open, the inner dies 35 are closed (see FIG. 5). At this time, the transfer sheet 10 is disposed so that the end opening 10 c in the cylindrical transfer sheet 10 coincides with the opening 45 of the cavity 42. The transfer sheet 10 can be smoothly inserted by fixing the transfer sheet 10 to an appropriate jig. If the cylindrical transfer sheet 10 can be inserted from the opening 45 even when the inner mold 35 is in the closed state, the inner mold 35 may be inserted after the inner mold 35 is closed. Further, after the insertion, one side of the inner mold 35 may be sucked to lightly adsorb one surface of the cylindrical transfer sheet 10. This state is indicated by a broken line X.

(Step 2)
Thereafter, as shown in FIG. 6, the deflated balloon 40 is inserted into the cylindrical transfer sheet 10 through the opening 45. Then, the balloon 40 is inflated by supplying the pressurized fluid L through the coupler 56, and the transfer sheet 10 is pressed against the cavity forming surface 32 on the surface of the balloon 40 (see FIG. 7). After pressing the transfer sheet 10 against the cavity forming surface 32 at a predetermined pressure for a certain period of time, suction X is performed as shown by the solid line through the suction paths 44 of both molds, and the transfer sheet 10 is pressed against the cavity forming surface of both molds 34. 32. When the inner mold 35 is formed of a porous metal, uniform adsorption is performed on the entire surface of the transfer sheet 10. When the inner mold 35 is made of a dense metal, it is adsorbed by the suction path 44. The cavity forming surface 32 may be a mirror surface, but this is made into a fine rough surface to form a minute gap between the surface of the transfer sheet 10 in contact with the cavity forming surface 32 and the rough surface, and the suction path 44 from the gap. In addition, the air tightness of the space between the cavity forming surface 32 and the transfer sheet 10 may be enhanced by allowing air to flow smoothly.
The timing of starting the suction X is preferably after completion of the inflation of the balloon 40 as described above.

  The balloon 40 may start to be inflated or may be inflated. After the suction, the pressurized fluid L is discharged through the coupler 56 to deflate the balloon 40, and the deflated balloon 40 is taken out from the cavity 42.

(Step 3)
As shown in FIGS. 8 and 9, the outer mold 36 is placed on the inner mold 35 so that the inner mold 35 is accommodated in the mold accommodating space 50, and the convex portions 48 are formed from both ends of the inner mold 35. The core mold 38 is attached so as to be inserted into the opening 45 of the cavity 42, the main body portion 47 of the core mold 38 is fitted to the entire circumference of the end portion of the inner mold 35, and the opening 45 is closed by the main body portion 47. The cavity 42 is in a state where only the molten resin injection hole 60 of the injection path 59 is opened. In this step, the suction X from the suction paths 44 and 44a is continued.

(Step 4)
As shown in FIG. 10, the molten resin injection path 58 and the core mold of the outer mold 36 are maintained while maintaining the state in which the transfer sheet 10 is sucked into the cavity forming surface 32 by continuing the suction X from the suction path 44. The molten resin Y is injected into the cavity 42 through the 38 injection paths 59 and the molten resin injection hole 60.

  At this time, the molten resin Y having a temperature close to 200 ° C. comes into contact with the transfer sheet 10, but as described above, the transfer sheet 10 is in close contact with the inner curved surface of the cavity forming surface 32. Is immediately conducted and radiated from the transfer sheet 10 to the mold 34, and the temperature of the transfer sheet 10 rises only to about 120 ° C. Therefore, the transfer sheet 10 is damaged by the heat from the molten resin Y even though the base sheet 12 and the design ink layer 14 constituting the transfer sheet 10 are made of a material having a lower heat resistant temperature than conventional materials. Can be avoided. The suction X ends at the same time as or after the completion of the injection, but can be ended when the transfer sheet 10 is not affected by the injection.

(Step 5)
After injecting the molten resin Y, the molten resin Y is cooled and solidified. After the cooling is finished, as shown in FIG. 11, the outer mold 36, the core mold 38, and the inner mold 35 are sequentially moved to open the mold, and the resin molded product Z having the transfer sheet 10 attached to the surface is formed. Take out. When the release layer 18 is provided between the base sheet 12 and the design ink layer 14, the design ink layer 14 (and the primer layer) is removed by peeling the base sheet 12 from the design ink layer 14. Only 16) can be transferred to the surface of the resin molded product Z.

  In addition, in-mold molding of the resin molded product Z can be performed without using the balloon 40. In this case, the procedure for inserting the balloon 40 into the inside of the transfer sheet 10 in the above (Step 2), the procedure for inflating the balloon 40 and pressing the transfer sheet 10 against the cavity forming surface 32, and the cavity 42 by contracting the balloon 40. The procedure of taking out from is omitted.

  Up to this point, the separation mold apparatus 30 including the inner mold 35, the outer mold 36, and the core mold 38 has been described. Subsequently, as illustrated in FIGS. 12 and 13, the inner mold 35 is provided. An integrated mold apparatus 30 constituted by a mold 34 integrated with the outer mold 36 and a core mold 38 will be briefly described. In this case, since the mold 34 is the same as the separated mold except that the inner mold 35 and the outer mold 36 are integrated, the common part (including the case where the balloon 40 is not used) is the description of the separated mold. Is incorporated into the integrated type and description thereof is omitted.

  For the integrated mold apparatus 30, the inner mold 35 is replaced with the mold 34 in (Step 1) and (Step 2). However, the case where the metal mold | die 34 cannot be made into a porous metal and the inner metal mold | die 35 is formed with a dense metal is applied. In (Step 3), since the outer mold 36 is integrated with the inner mold 35 in the integrated mold, the convex portions 48 are inserted into the openings 45 of the cavity 42 from both ends of the mold 34. The core mold 38 is attached. Also in (Step 4), the outer mold 36 is replaced with the mold 34. In (Step 5), “the outer mold 36, the core mold 38, and the inner mold 35 are sequentially moved to open the mold”, and “the mold 34 and the core mold 38 are moved sequentially to open the mold”. And read "." As a result, in-mold molding that can be applied to the entire interior / exterior material product having a complicated shape in the integrated mold apparatus 30 becomes possible.

10: transfer sheet, 12: substrate sheet, 14: design ink layer, 16: primer layer, 18: release layer, 30: mold apparatus, 32: cavity forming surface, 34: mold (female), 35 : Inner mold, 36: Outer mold, 38: Core mold, 40: Balloon, 42: Cavity, 44, 44a: Suction path, 45: Opening of (cavity), 46: Mold closing surface, 47: Main body part, 48: convex part, 50: mold housing space, 52: space forming surface, 54: body part, 56: coupler, 58: molten resin injection path, 59: injection path, 60: molten resin injection hole, 62: cooling water Supply pipe, 64: Cooling water discharge pipe, CW: Cooling water, L: Pressurized fluid, X: Suction, Y: Molten resin, Z: Resin molded product

Claims (7)

Between the cavity forming surfaces of the mold forming a cavity having an opening in at least one place, a transfer sheet rolled up into a cylindrical shape is disposed so that the end opening of the transfer sheet coincides with the opening,
Depressurizing between the transfer sheet and the cavity forming surface through a suction path formed in the mold and opening to the cavity forming surface, and adsorbing the transfer sheet to the cavity forming surface;
An in-mold molding method in which the opening is closed with a core mold while the transfer sheet is adsorbed to the cavity forming surface to seal the cavity, and then the molten resin is injected into the transfer sheet. The transfer sheet is composed of an inner mold and an outer mold that covers the inner mold, and the transfer sheet rolled into a cylindrical shape between the cavity forming surfaces provided in the inner mold. The end opening of the transfer sheet is disposed so as to coincide with the opening of the cavity,
Depressurizing between the transfer sheet and the cavity forming surface through a suction path formed in the inner mold and opening to the cavity forming surface, and adsorbing the transfer sheet to the cavity forming surface;
While the transfer sheet is adsorbed on the cavity forming surface, the outer mold is covered with the inner mold,
The in-mold molding according to claim 1, wherein the core mold is advanced toward the inner mold to close the opening of the cavity to seal the cavity, and then the molten resin is injected into the transfer sheet. Method. After disposing the transfer sheet between the cavity forming surfaces, until the transfer sheet is vacuum-adsorbed to the cavity forming surface,
A balloon that expands and contracts when pressurized fluid is supplied and discharged is inserted into the transfer sheet through the opening in a contracted state, and the balloon is expanded by supplying the pressurized fluid and The transfer sheet is pressed against the cavity forming surface to be adhered,
After the transfer sheet is vacuum-adsorbed on the cavity forming surface and before the cavity is sealed,
The in-mold molding method according to claim 1 or 2, wherein the balloon contracted by discharging the pressurized fluid is taken out from the opening. After disposing the transfer sheet between the cavity forming surfaces and before inserting the balloon into the transfer sheet,
The in-mold molding method according to claim 3, wherein the transfer sheet is adsorbed to one of the cavity forming surfaces.   5. The in-mold molding method according to claim 3, wherein a dynamic friction coefficient of a surface of the balloon is 4.0 or less. The transfer sheet has a highly elastic resin base material sheet at room temperature, and a pattern ink layer formed on the surface of the base material sheet and highly elastic at normal temperature. And having an elongation rate of 200% or more at room temperature and an elastic recovery rate of 40% or less at 60% elongation, and
The in-mold molding method according to claim 1, wherein the resin constituting the base sheet has a melting point of 120 ° C. or higher.   A resin molded product produced by the in-mold molding method according to claim 1.

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