JP5667526B2 - Method of performing in-mold molding of complex shape, transfer sheet used for in-mold molding, and resin molded product formed by the method - Google Patents

Description

  The present invention relates to a decorative and transfer sheet and method used for in-mold molding of general interior and exterior material products used for automobiles, airplanes, heavy machinery, cruisers, houses, furniture, home appliances, and the like, and products thereof.

  A decorative resin / transfer sheet (PET original) on which a design pattern is printed in advance is sandwiched between male and female molds of an injection molding machine, and then the molten resin (plastic) is injected into the mold. In-mold molding in which a printed design pattern is transferred to a resin by heat or the like is widely used for decorating resin molded products such as automobile parts and home 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. There is an advantage that there is no reduction in yield due to quality defects at the time, lead time is shortened, and the yield of the total process can be controlled. In addition, since in-mold molding enables hard coating at the time of molding, in recent years, the number of cases in which in-mold molding is adopted in the manufacture of mobile phone housings is increasing.

  As a base film of a transfer sheet used for such in-mold molding, a polyethylene terephthalate biaxially stretched film is disclosed in JP-A-64-45699, JP-A-3-253317, JP-A-3-288699, and the like. A method using a polyvinyl chloride film is proposed in Japanese Patent Laid-Open No. 3-288700.

Japanese Unexamined Patent Publication No. 64-45699 JP-A-3-253317 JP-A-3-288699 JP-A-3-288700

  Among these, polyethylene terephthalate biaxially stretched film has excellent properties such as strength, heat resistance, surface smoothness, and non-contamination, and is therefore widely used as a base film for in-mold molding. As is well known, since it is highly crystallized by stretching, heat setting, etc., the elongation at break is small, and the resin molded product has a complicated shape with a high degree of deep drawing (for example, a shape having a corner corner of 8R or less). Then, there was a problem that the base film was torn during in-mold molding and could not function as a transfer sheet.

  On the other hand, polyvinyl chloride film can increase elongation at break by adding a plasticizer, and can follow relatively well even in complicated shapes with a high degree of deep drawing, but there is a problem with heat resistance. In addition, there was a fatal problem that the plasticizer bleeds out and contaminates the transfer surface, and this film was not satisfactory.

  In general, in the vacuum molding transfer method and the simultaneous molding transfer method, the transfer sheet is made plastic by the heat of the injected molten resin, and at the same time, the transfer sheet is stretched by the injection pressure and conforms to the mold surface. Therefore, in areas where there are complicated curved surfaces or undercuts in resin molded products, the pattern printed on the transfer sheet will increase in length and look worse (especially if the pattern contains characters). At the same time, it was not possible to decorate the back of the resin molded product (particularly a three-dimensional molded product) neatly, such as thinning the film thickness and cutting the handle.

  The present invention has been made in view of such circumstances, the purpose of which is to manufacture a resin molded product having a high degree of deep drawing and a resin molded product having an undercut, the film is torn during in-mold molding, Alternatively, an in-mold molding method that is optimal for obtaining a resin molded product having a beautiful appearance with little distortion such as a design pattern without generating wrinkles, a transfer sheet used therefor, and the method is used. It is in providing a molded resin molded product.

The invention described in claim 1 relates to a method of performing in-mold molding of a complicated shape,
“It has 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, and the pattern ink layer 14 is formed. When covering the opening 40 of the cavity mold 30 in which the cavity 32 having a predetermined shape is covered with the transfer sheet 10 having a dynamic friction coefficient of 4.0 or less on the surface opposite to the surface, the surface on the opposite side is used as the cavity. After covering the opening forming surface 41 of the mold 30 toward 32, suction is performed from the opening suction path 42c provided on the opening forming surface 41 to suck the transfer sheet 10 to the opening forming surface 41,
Next, even if the holding plate 34 is advanced toward the opening forming surface 41 and the suction from the opening surface suction path 42c is stopped, the transfer sheet 10 does not move undesirably and the inside of the cavity 32 is decompressed. A gap between the opening forming surface 41 and the pressing plate 34 to ensure that the transfer sheet 10 can slide on the opening forming surface 41 without resistance and stick to the inner surface of the cavity 32,
After stopping the suction from the opening surface suction path 42c, the inside of the cavity 32 is depressurized, and the transfer sheet 10 is sucked in while sliding the surface of the cavity mold 30 to be in close contact with the inner surface of the cavity 32,
The mold 30 is closed while the transfer sheet 10 is in close contact with the inner surface of the cavity 32, and then the molten resin is injected into the cavity 32 ".

  In this method, the transfer sheet 10 having the base sheet 12 in which the surface opposite to the surface on which the design ink layer 14 is formed, that is, the surface facing the mold 30 is made slippery is sucked into the cavity 32 having a predetermined shape. The molten resin is injected into the cavity 32 after being brought into close contact with the inner surface of the cavity 32.

  More specifically, when the transfer sheet 10 is sucked into the cavity 32, the opposite surface having high slidability smoothly slides on the surface of the cavity 32 even if the cavity 32 is deep and deeply drawn. Slides into the cavity 32. At this time, the transfer sheet 10 is pulled into the cavity 32 without substantially extending in the sliding state, so that the pattern ink layer 14 printed on the transfer sheet 10 keeps the same pattern in the cavity 32. It will be located at the planned location.

  Moreover, since the transfer sheet 10 is a material having high stretchability at room temperature and the design ink layer 14 having high stretchability at room temperature is formed on the surface thereof, the surface shape of the cavity 32 is complicated. Even if there is an undercut UC part on the opening or inner surface of the slab, the high stretchability causes the suction part (negative pressure) to stretch the stretched part and the narrow part to react quickly. It shrinks and adheres to the entire inner surface of the cavity 32 following the surface shape. At this time, although depending on the inner surface shape of the cavity 32, the unevenness of the inner surface shape and the undercut UC are usually shallower than the depth of the cavity 32, so the elongation at this point is not so much as to deform the pattern, and therefore this adhesion If the resin is injected in this state, the design is transferred as it is to the surface of the resin molded product Z without being deformed.

Further, as described above, even if the surface shape of the cavity 32 is complicated, the transfer sheet 10 closely adheres to the inner surface of the cavity 32 in a state where the surface of the transfer sheet 10 is uniformly extended by the suction pressure (negative pressure). Therefore, when injected into the cavity 32 in this state, the heat of the injected molten resin is immediately conducted to the mold 30 through the transfer sheet 10, and the injection pressure of the molten resin or the heat of the molten resin is used. Thus, it is possible to avoid a high temperature as in the conventional in-mold molding in which the transfer sheet is stretched . Therefore, even though those heat resistance is inferior as a base sheet 12 and the pattern ink layer 14 constituting the transfer sheet 10 may be used as long as highly elastic material at room temperature.

  In addition, in the in-mold molding of the present invention, as described above, the transfer sheet 10 is stretched evenly at room temperature to a certain degree before injection and is brought into close contact with the inner surface of the cavity 32, so that high temperature and high pressure at the time of injection is applied to the transfer sheet 10. However, the transfer sheet 10 is not torn or wrinkles are generated, and in addition, the elongation of the pattern on the complicated curved surface in the resin molded product Z is undesirably larger than other flat portions, It can be avoided that the portion is distorted and becomes uncomfortable with a sense of incongruity.

The invention described in claim 2 is an improvement of the method of in-mold molding described in claim 1,
“It has 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, and the pattern ink layer 14 is formed. When covering the opening 40 of the cavity mold 30 in which the cavity 32 having a predetermined shape is covered with the transfer sheet 10 having a dynamic friction coefficient of 4.0 or less on the surface opposite to the surface, the surface on the opposite side is used as the cavity. After covering the opening forming surface 41 of the mold 30 toward 32, suction is performed from the opening suction path 42c provided on the opening forming surface 41 to suck the transfer sheet 10 to the opening forming surface 41,
Next, even if the holding plate 34 is advanced toward the opening forming surface 41 and the suction from the opening surface suction path 42c is stopped, the transfer sheet 10 does not move undesirably and the inside of the cavity 32 is decompressed. A gap between the opening forming surface 41 and the pressing plate 34 to ensure that the transfer sheet 10 can slide on the opening forming surface 41 without resistance and stick to the inner surface of the cavity 32,
After the suction from the opening surface suction path 42 c is stopped, the core mold 36 having the convex portion 37 is inserted into the cavity 32, and the transfer sheet 10 is inserted into the cavity mold 30 at the tip of the convex portion 37. The surface is slid and extended into the cavity 32, and
The inside of the cavity 32 is depressurized, and the transfer sheet 10 is sucked into the cavity 32 while sliding the surface of the cavity mold 30 further, and is brought into close contact with the inner surface of the cavity 32,
The mold 30 is closed while the transfer sheet 10 is in close contact with the inner surface of the cavity 32, and then the molten resin is injected into the cavity 32 ".

  According to the second aspect of the present invention, a step of pushing the transfer sheet 10 into the cavity 32 at the tip of the convex portion 37 of the core mold 36 is added as a step before sucking the transfer sheet 10 by depressurizing the inside of the cavity 32. Since the transfer sheet 10 is relatively slowly pushed into the cavity 32 using the convex portion 37 of the core mold 36 and then sucked in quickly, the cavity 32 is decompressed and the transfer sheet 10 is sucked in. Compared to the above, the possibility that the transfer sheet 10 is torn or wrinkles are generated can be further reduced.

The invention described in claim 3
“A substrate base sheet 12 having high elasticity at room temperature and a pattern ink layer 14 formed on the surface of the base sheet 12 and having high elasticity at room temperature, and the pattern ink layer 14 The surface opposite to the surface on which the surface is formed has high slidability, and 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 60% elongation. And
The dynamic friction coefficient on the surface of the base sheet 12 opposite to the surface on which the design ink layer 14 is formed is 4.0 or less, and
The resin constituting the base sheet 12 is a transfer sheet 10 ”having a melting point of 120 ° C. or higher.

  The transfer sheet 10 described in claim 3 is suitable for direct use in the in-mold forming method described in claim 1 or 2.

  The invention described in claim 4 is a resin molded product Z formed by using the method of claim 1 or 2.

  The resin molded product Z formed using the method according to claim 1 or 2 has a beautiful appearance with little distortion such as a design pattern, without the transfer sheet 10 being torn or wrinkling. It has the characteristics.

  According to the present invention, when producing a resin molded product having a high deep drawability or a resin molded product having an undercut, the transfer sheet is not torn or wrinkles are generated during in-mold molding, and the design pattern In-mold molding was most suitable for obtaining a resin molded product having a beautiful appearance with little distortion such as.

It is sectional drawing of the transfer sheet concerning this invention. It is sectional drawing of the other Example concerning the transfer sheet of this invention. It is sectional drawing of the metal mold | die for injection molding used for this invention. It is sectional drawing which shows the procedure of injection molding. It is sectional drawing which shows the procedure of injection molding. It is sectional drawing which shows the procedure of injection molding. It is sectional drawing which shows the procedure of injection molding. It is sectional drawing which shows the procedure of injection molding. It is sectional drawing which shows the procedure of injection molding.

  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, a procedure for performing in-mold molding using the transfer sheet 10 will be described. Thereafter, specific examples will be described together with comparative examples.

  As shown in FIG. 1, 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 sheet 12 is made of a material having an elongation rate of 200% or more at room temperature and an elastic recovery rate of 40% or less at 60% elongation. A polyolefin film, a urethane elastomer film, or a vinyl chloride film can be mentioned.

  Moreover, the surface (upper surface in the figure) opposite to the surface (lower surface in the figure) on which the design ink layer 14 is formed in the base sheet 12 has low slip resistance. Specifically, the coefficient of dynamic friction (= MIU) is 4.0 or less. In order to reduce the MIU to 4.0 or less, for example, the surface in contact with the mold is formed with fine irregularities having a center line average roughness of about several microns to several tens of microns to prevent adhesion between materials. Can reduce the frictional force. This method is particularly effective for adhesive vinyl chloride sheets and urethane sheets. Further, as a specific example of the formation of irregularities, it is conceivable to add a matting agent such as silica fine particles to at least the surface of the base sheet 12 or to physically emboss the surface. . On the contrary, it is also possible to improve the sliding of the base material sheet 12 by making fine irregularities of about several microns to several tens of microns on the surface of the mold used for in-mold molding according to the present invention.

  Further, as will be described later, in the in-mold molding using the transfer sheet 10 of this embodiment, the molten resin is injected after the transfer sheet 10 is brought into close contact with the surface of the mold. Since heat is immediately conducted to the mold through the transfer sheet 10, the transfer seed 10 does not become as hot as before. For this reason, the resin constituting the base sheet 12 can avoid melting and thermal deterioration of the transfer sheet 10 even if it receives heat from the molten resin at the time of injection. A material excellent in tearing property can be adopted as the first selection of the base sheet 12, and a material having a low melting point (having a melting point of about 120 ° C.) can also be used.

  As 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, these are not specific.

  Conventionally, the ink used for in-mold molding has to be selected to have high cohesive strength and low elasticity at room temperature in order to increase the heat resistance to withstand the high temperatures caused by the heat received from the molten resin during injection. Since it was not obtained, the pattern ink layer used in the conventional method had to be stretched by preheating or heating with the heat of the molten resin at the time of injection. However, in this example, the transfer sheet 10 including the design ink layer 14 is not as hot as the conventional one, and therefore, the design ink layer 14 is highly stretchable at room temperature as in the case of the substrate sheet 12 (on the other hand, Those having poor heat resistance can be used. However, the design ink layer 14 having heat resistance that can withstand a temperature rise (130 to 150 ° C.) due to heat during 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. The “symbol” is a concept including not only a pattern 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. 2, 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 surface of the resin molded product Z is in a state in which the base sheet 12 is laminated. When the release layer 18 is provided, the base sheet 12 is made to be a design ink layer after injection molding. By peeling from the pattern 14, the design ink layer 14 (and the primer layer 16) is transferred.

  As shown in FIG. 3, an injection mold 28 of an injection molding machine that performs in-mold molding using such a transfer sheet 10 is generally a mold (female mold) in which a cavity 32 having a predetermined shape is formed. 30, a pressing plate 34, and a core type (male type) 36.

  The mold 30 is configured by combining a bottom core 39 and a plurality of slide cores 38, which are attached to a movable die plate and form the bottom of a cavity 32 (described below). In a state where the bottom core 39 and the slide cores 38 are combined, a cavity 32 having a predetermined shape (that is, the external shape of the resin molded product) is formed inside thereof, and is formed on one surface (lower surface in the drawing). Is formed with an opening 40 into which a convex portion 37 (described later) of the core mold 36 is inserted (this surface is referred to as an “opening forming surface 41”).

  One end of each slide core 38 and bottom core 39 constituting the mold 30 is open to the cavity 32 forming surface (that is, the inner surface of the mold 30) or the opening forming surface 41, and the other end. Is formed with a suction path 42 connected to a suction pump (not shown). In the present embodiment, a bottom suction path 42 a formed at the bottom core 39 and having one end opened at the bottom of the cavity 32 and a side suction formed at each slide core 38 and one end opened at the side of the cavity 32. A path 42b and an opening surface suction path 42c whose one end opens to the opening forming surface 41 are formed.

  The pressing plate 34 is a plate material in which a core mold insertion hole 44 into which the convex portion 37 of the core mold 36 is inserted is formed at the center, and a surface 34a of the pressing plate 34 facing the mold 30 is the cavity. The mold 30 can be in close contact with the opening forming surface 41 of the mold 30.

  The core mold 36 is attached to a fixed die plate, and has a mold closing surface 46 that closes the opening 40 of the mold 30 and a projection 37 that is inserted into the cavity 32 to define the inner shape of the resin molded product Z. In the illustrated embodiment, the molten resin injection path 50 having one end opened at the tip of the convex portion 37 and the other end connected to a molten resin supply device (not shown) passes through the core mold 36 vertically in the figure. Is formed.

  Next, a procedure for performing in-mold molding (in particular, in-mold molding of a resin molded product Z having an undercut UC) using the transfer sheet 10 and the injection mold 28 described above will be described.

(Step 1)
As shown in FIG. 4, the transfer sheet 10 and the injection mold 28 described above are prepared, and the surface of the transfer sheet 10 having low slip resistance (the surface opposite to the surface on which the design ink layer 14 is formed). Is directed to the cavity 32 formed in the mold 30 and the transfer sheet 10 is placed on the opening forming surface 41 so as to cover the opening 40 of the mold 30, and then the transfer sheet is sucked from the opening suction path 42 c. 10 is sucked onto the opening forming surface 41.

(Step 2)
The transfer sheet 10 moves undesirably even when the holding plate 34 is moved forward toward the opening forming surface 41 while the transfer sheet 10 is sucked onto the opening forming surface 41 and the suction from the opening surface suction path 42c is stopped. In addition, as will be described later, a gap that allows the transfer sheet 10 to slide on the opening forming surface 41 without resistance by the suction from the bottom suction path 42a and the side suction path 42b (for example, stick to the inner surface of the cavity 32) (for example, , 0.1 mm to 0.2 mm) in a state secured with the opening forming surface 41.

(Step 3)
The suction from the opening surface suction path 42c is stopped, and thereafter the suction from the bottom suction path 42a and the side suction path 42b is started to depressurize the cavity 32, and the transfer sheet 41 is slid while sliding the opening forming surface 41 10 is sucked and brought into close contact with the inner curved surface of the cavity 32 (see FIG. 5). As described above, the surface on the opening forming surface 41 side of the transfer sheet 10 is a surface having low slip resistance, and when the transfer sheet 10 is drawn into the cavity 32, the opening forming surface 41 smoothly slides. A part of the transfer sheet 10 is not torn or stretched, and the pattern drawn on the pattern ink layer 14 is not undesirably deformed. In addition, since the base sheet 12 and the design ink layer 14 having high elasticity at room temperature are used for the transfer sheet 10, it is not necessary to heat and soften the transfer sheet 10 as a pre-process. Only by suction, the transfer sheet 10 can be brought into close contact with the inner curved surface of the cavity 32 accurately.

(Step 4)
The mold 30 is advanced while maintaining the close contact state by the suction from the bottom suction path 42a and the side suction path 42b, and the convex part 37 of the mold 30 is inserted into the cavity 32 from the opening 40 (FIG. 6). After the cavity 32 is closed with the mold closing surface 46, the molten resin is injected into the cavity 32 through the molten resin injection path 50 (see FIG. 7).

  At this time, the molten resin having a temperature close to 200 ° C. comes into contact with the transfer sheet 10. However, since the transfer sheet 10 is in close contact with the inner curved surface of the cavity 32 as described above, the heat of the molten resin is transferred to the transfer sheet 10. Then, the heat is immediately transferred to the mold 30 (slide core 38 and bottom core 39), 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 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 the conventional material. Can be avoided.

(Step 5)
After injecting the molten resin, the molten resin is cooled and solidified. After the cooling is completed, the core mold 36, the slide core 38, and the pressing plate 34 are moved to open the mold, and the resin molded product Z is taken out (see FIGS. 8 to 9). Thereafter, the extra transfer sheet 10 is trimmed from the resin molded product Z as necessary. 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.

  EXAMPLES Examples and comparative examples according to the present invention will be described below, but the present invention is not limited to the examples.

[Example 1-1]
Polyurethane gravure ink is applied to a polyolefin sheet of 100 μm thickness (“Convenience Pure Soft PP type (multi-layer PP / EVA / PP)” manufactured by Okamoto Co., Ltd.) using a gravure rotary tester so that the dry film thickness is 3 μm. And applied. After drying this at 60 ° C. for 5 minutes, PP primer (“NAXPP primer” manufactured by Nippon Paint Co., Ltd.) was further applied using a gravure rotary tester so that the dry film thickness was 5 μm, and finally 60 ° C. And dried for 5 minutes to obtain a transfer sheet 10 used for in-mold molding.

The elongation rate of the obtained transfer sheet 10 (the elongation rate of three layers including the base material sheet (polyolefin sheet) layer 12, the pattern (gravure) ink layer 14 and the primer layer 16) is normal temperature (range of 10 to 40 ° C). ) And more than 800%. Table 1 shows the elastic recovery rate when the elongation rate is changed.

  Further, a differential scanning calorimeter (DSC3100; manufactured by Mac Science Co., Ltd., heating rate 2 ° C./min) was used for polyolefin sheet (“Convenience Pure Soft PP type (multi-layer PP / EVA / PP) manufactured by Okamoto Co., Ltd.)” DS) measurement was performed. DSC measurement is a method for measuring endotherm and heat generation while slowly raising or lowering the temperature of a sample. As a result, it was found that the olefin sheet had glass transition points at 45.3 ° C., 77.7 ° C., and 119.3 ° C., and a melting point at 122.8 ° C.

  In order to suppress the elongation and deformation of the pattern, as described above, in the present invention, the transfer sheet 10 is slid on the surface (opening formation surface 41) of the mold 30 and is brought into close contact with the inner curved surface of the cavity 32. Therefore, using FRICTION TESTER (manufactured by Kato Tech Co., Ltd .; KES-SE), the surface of the test material (the surface on which the design ink layer 14 is formed on the transfer sheet 10) is determined. The average friction coefficient of the opposite surface) and its variation were measured. The friction coefficient is measured by simulating a human finger and using a contact with a shape of 10 smooth 0.5mm diameter piano wires arranged on a plane (contact load is 50gf, feed) (Speed is 1.0mm / sec.)

  There are MIU (average friction coefficient) and MMD (friction coefficient variation = average deviation) as characteristic values that are considered to well represent the surface characteristics of the substrate sheet 12. It can be said that the larger the MIU value, the more rough the surface becomes, and the more easily caught by the fingers, and the smaller the MMD value, the more constant the MIU value and the smoother it is. The transfer sheet 10 in this example had an MIU of 2.18 and an MMD of 1.12.

[Example 1-2]
Polyurethane gravure ink is applied to a 70 μm thick PVC sheet (Nippon Wae Block Co., Ltd. “Tough Neil Pear Clear”) using a gravure rotary tester so that the dry film thickness is 3 μm. After drying for 5 minutes, PP primer (“NAXPP primer” manufactured by Nippon Paint Co., Ltd.) was applied to a thickness of 5 μm using a gravure rotary tester. This was dried at 60 ° C. for 5 minutes to obtain a transfer sheet 10. The elongation rate of the obtained transfer sheet 10 (the elongation rate of three layers including the base material sheet (polyolefin sheet) layer 12, the pattern (gravure) ink layer 14 and the primer layer 16) is normal temperature (range of 10 to 40 ° C). ) And 236%. Table 2 shows the elastic recovery rate when the elongation rate was changed.

  Furthermore, the DSC measurement of the vinyl chloride sheet (“Tuff Neil Clear” manufactured by Nippon Wae Block Co., Ltd.) was performed using a differential scanning calorimeter (DSC3100; manufactured by Mac Science Co., Ltd., heating rate 2 ° C./min). . This PVC sheet had a melting point of 227.7 ° C. Further, the MIU of this sheet was 2.79, and the MMD was 0.90.

[Example 2-1]
The transfer sheet 10 prepared in Example 1-1 was used. The resin molded product Z was modeled on a U-shaped hunting gun, and an injection mold 28 as shown in FIG. 3 was prepared. Using this injection mold 28, in-mold molding was performed as follows.
(Injection conditions)
Molding resin: Prime PP G-20%
Injection temperature: 220 ° C. Primary pressure: 100 MPa Holding pressure: 50 MPa Injection speed: 30 mm / sec.
(Molding process)
Step 1: Using the transfer sheet 10 of the present invention described above, the transfer sheet 10 is disposed so that the surface having a dynamic friction coefficient of 4.0 or less faces the cavity 32, and then sucked from the opening surface suction path 42 c, and the mold 30 The transfer sheet 10 is affixed to the opening forming surface 41. Next, the pressing plate 34 is moved to the pressing position of the transfer sheet 10 (a position in which a clearance of 0.1 to 0.2 mm is secured between the opening forming surface 41 so that the transfer sheet 10 can slide without resistance).
Step 2: At the same time as closing the opening surface suction path 42 c, the air in the cavity 32 is evacuated through the bottom suction path 42 a and the side suction path 42 b, and the transfer sheet 10 is drawn into the cavity 32 to closely contact the inner curved surface of the cavity 32.
Step 3: After the pressing plate 34 is brought into close contact with the opening forming surface 41, the mold 30 is closed, and injection molding is performed while the suction of the transfer sheet 10 is continued through the bottom suction path 42a and the side suction path 42b. .
Step 4: After cooling is completed, the bottom suction path 42a and the side suction path 42b are closed, and the mold 30 is retracted. Further, the holding plate 34 is also returned to the original position.
Step 5: Open each slide core 38 to the left and right and take out the resin molded product Z. When the transfer sheet 10 in which the release layer 18 is provided between the base sheet 12 and the design ink layer 14 is used, only the primer layer 16 and the design ink layer 14 are removed by peeling the base sheet 12. Transfer and complete in-mold molding.

  The resin molded product Z taken out could be transferred to the back surface with the undercut UC cleanly and without pattern elongation without being able to break the weld or film.

[Example 2-2]
The transfer sheet 10 prepared in Example 1-2 was used, the mold and injection conditions were the same as in Example 2-1, and molding was performed in the following steps.
(Molding process)
Step 1: Using the transfer sheet 10 of the present invention described above, the transfer sheet 10 is disposed so that the surface having a dynamic friction coefficient of 4.0 or less faces the cavity 32, and then sucked from the opening surface suction path 42 c, and the mold 30 The transfer sheet 10 is affixed to the opening forming surface 41. Next, the pressing plate 34 is moved to the pressing position of the transfer sheet 10 (a position in which a clearance of 0.1 to 0.2 mm is secured between the opening forming surface 41 so that the transfer sheet 10 can slide without resistance).
Step 2: At the same time as closing the opening surface suction passage 42c, the mold 30 is advanced, the transfer sheet 10 is pushed in by the convex portion 37 of the core die 36, and the transfer sheet 10 is moved into the cavity 32 while sliding the opening forming surface 41. To stretch elastically.
Step 3: The air in the cavity 32 is evacuated through the bottom suction path 42 a and the side suction path 42 b, and the transfer sheet 10 is drawn into the cavity 32 to closely contact the inner curved surface of the cavity 32.
Step 4: The pressing plate 34 is brought into close contact with the opening forming surface 41, and the cavity mold 30 is completely closed.
Step 5: Injection molding is performed in a state where suction of the transfer sheet 10 is continued through the bottom suction path 42a and the side suction path 42b.
Step 6: After cooling is completed, the bottom suction path 42a and the side suction path 42b are closed, and the mold 30 is moved backward. Further, the holding plate 34 is also returned to the original position.
Step 7: Open each slide core 38 to the left and right and take out the resin molded product Z. When the transfer sheet 10 in which the release layer 18 is provided between the base sheet 12 and the design ink layer 14 is used, the base sheet 12 is peeled off to transfer only the primer layer 16 and the design ink layer 14. In-mold molding is completed.

  The resin molded product Z taken out was able to be transferred cleanly to the back surface with the undercut UC without being able to break the weld or film. Furthermore, the lattice pattern in the deep-drawn portion and undercut UC portion could be molded and transferred with little pattern elongation and deformation.

[Comparative Example 1-1]
A polyurethane-based gravure ink was applied to a urethane elastomer sheet having a thickness of 50 μm (“Hai-Fas” manufactured by Okura Kogyo Co., Ltd.) using a gravure rotary tester so that the dry film thickness was 3 μm. After drying this at 60 ° C. for 5 minutes, PP primer (“NAXPP primer” manufactured by Nippon Paint Co., Ltd.) was further applied using a gravure rotary tester so that the dry film thickness was 5 μm. A transfer sheet was obtained by drying for a minute.

The transfer sheet thus obtained has an elongation ratio (elongation ratio of three layers including a base material sheet (urethane elastomer sheet) layer, a pattern (gravure) ink layer, and a primer layer) of 526 at room temperature (range of 10 to 40 ° C.). %Met. Table 3 shows the elastic recovery rate when the elongation percentage was changed.

  Furthermore, DSC measurement of the urethane elastomer sheet was performed with a differential scanning calorimeter (DSC3100; manufactured by Mac Science Co., Ltd., heating rate 2 ° C./min). This transfer sheet had glass transition points of 14.7 ° C., 23.9 ° C., 34.2 ° C., and 48.6 ° C., and had a melting point at 105.7 ° C. The transfer sheet had an MIU of 3.52 and an MMD of 0.83.

[Comparative Example 2-1]
The transfer sheet prepared in Comparative Example 1-1 was used. The resin molded product was modeled on a U-shaped hunting gun tip, and an injection mold 28 as shown in FIG. 2 was prepared. Using this injection molding die 28, in-mold molding was performed in the manner shown in Example 2-1.

  The molded product according to this comparative example has a PL (parting line) portion (in this embodiment, a surface where the transfer sheet is sandwiched between the mold 30 and the core 36), the transfer sheet breaks, welds and wrinkles The defect which seems to have a problem in heat resistance occurred.

[Comparative Example 1-2]
Polyurethane gravure ink was applied to a polyester sheet having a thickness of 125 μm (“Soft Shine” manufactured by Toyobo Co., Ltd.) using a gravure rotary tester so that the dry film thickness was 3 μm. After drying this at 60 ° C. for 5 minutes, PP primer (“NAXPP primer” manufactured by Nippon Paint Co., Ltd.) was further applied using a gravure rotary tester so that the dry film thickness was 5 μm. A transfer sheet was obtained by drying at 60 ° C. for 5 minutes. The resulting transfer sheet has an elongation ratio (elongation ratio of three layers including a base sheet (polyester-based sheet) layer, a pattern (gravure) ink layer, and a primer layer) of 100 at room temperature (range of 10 to 40 ° C.). %Met. Table 4 shows the elastic recovery rate when the elongation percentage was changed.

  Furthermore, DSC measurement of the polyester sheet was performed with a differential scanning calorimeter (DSC3100; manufactured by Mac Science Co., Ltd., heating rate 2 ° C./min). This sheet had a melting point of 222.7 ° C.

[Comparative Example 2-2]
The transfer sheet prepared in Comparative Example 1-2 was used. The molded product was modeled on a U-shaped hunting gun tip, and an injection mold 28 as shown in FIG. 3 was prepared. In-mold molding was performed using the injection mold 28 in the manner shown in Example 2-1, but the transfer sheet was caught in the mold at the time of mold clamping, and was too hard and poorly stretched. The mold could not be damaged and could not be molded.

[Comparative Example 1-3]
A polyurethane-based gravure ink was applied to a polyvinyl chloride sheet having a thickness of 70 μm (“Tough Neil Clear” manufactured by Nippon Wae Block Co., Ltd.) using a gravure rotary tester so that the dry film thickness was 3 μm. This was dried at 60 ° C. for 5 minutes, and further a PP primer (“NAXPP primer” manufactured by Nippon Paint Co., Ltd.) was applied using a gravure rotary tester so that the dry film thickness was 5 μm. A transfer sheet was obtained by drying at 5 ° C. for 5 minutes. The resulting transfer sheet has an elongation rate (elongation rate of 3 layers including a base sheet (polyolefin sheet) layer, a pattern (gravure) ink layer, and a primer layer) of 320% at room temperature (range of 10 to 40 ° C.). Met. Table 5 shows the elastic recovery rate when the elongation rate was changed.

  Furthermore, DSC measurement was performed on a PVC sheet (“Tough Neil Clear” manufactured by Nippon Wae Block Co., Ltd.) using a differential scanning calorimeter (DSC 3100; manufactured by Mac Science Co., Ltd., heating rate 2 ° C./min). It was. This PVC sheet had a melting point of 233.5 ° C. Moreover, MIU of this polyvinyl chloride sheet was 6.46, and MMD was 1.58.

[Comparative Example 2-3]
The in-mold transfer sheet prepared in Comparative Example 1-2 was used. The molded product was modeled on a U-shaped hunting gun tip, and an injection mold 28 as shown in FIG. 3 was prepared. Using this injection molding die 28, in-mold molding was performed in the manner shown in Example 2-1.

  However, the transfer sheet used was very slippery and partially extended from the edge of the cavity 32 and could not follow the inner curved surface of the cavity 32. It was torn and the molded product could not be obtained.

DESCRIPTION OF SYMBOLS 10 ... Transfer sheet 12 ... Base material sheet 14 ... Design ink layer 16 ... Primer layer 18 ... Release layer 28 ... Mold for injection molding 30 ... Mold type (female type)
32 ... Cavity 34 ... Presser plate 36 ... Core type (male type)
37 ... (core type) convex portion 38 ... slide core 39 ... bottom core 40 ... opening 41 ... opening forming surface 42 ... suction path 42a ... bottom suction path 42b ... side suction path 42c ... opening surface suction path 44 ... core type Insertion hole 46 ... Mold closing surface 50 ... Molten resin injection path Z ... Resin molded product

Claims (4)

It has a resin base sheet that is highly stretchable at room temperature and a pattern ink layer that is formed on the surface of the base sheet and is highly stretchable at room temperature, and is opposite to the surface on which the pattern ink layer is formed. When a transfer sheet having a coefficient of dynamic friction on the side surface of 4.0 or less is used to cover the opening of the cavity mold in which the cavity having a predetermined shape is formed, the opening of the cavity mold is formed with the opposite surface facing the cavity. After covering the surface, the transfer sheet is sucked to the opening forming surface by performing suction from the opening suction path provided on the opening forming surface,
Next, the transfer plate does not move undesirably even when the holding plate is moved forward toward the opening forming surface and suction from the opening surface suction path is stopped, and the transfer is performed when the inside of the cavity is decompressed. A gap between the opening forming surface and the pressing plate is secured between the opening forming surface and the pressing plate so that the sheet can slide on the opening forming surface without resistance and stick to the inner surface of the cavity.
After stopping suction from the opening surface suction path, the inside of the cavity is depressurized, and the transfer sheet is sucked in while sliding the surface of the mold, and is brought into close contact with the inner surface of the cavity,
An in-mold molding method characterized in that the mold is closed with the transfer sheet in close contact with the inner surface of the cavity, and then molten resin is injected into the cavity. It has a resin base sheet that is highly stretchable at room temperature and a pattern ink layer that is formed on the surface of the base sheet and is highly stretchable at room temperature, and is opposite to the surface on which the pattern ink layer is formed. When a transfer sheet having a coefficient of dynamic friction on the side surface of 4.0 or less is used to cover the opening of the cavity mold in which the cavity having a predetermined shape is formed, the opening of the cavity mold is formed with the opposite surface facing the cavity. After covering the surface, the transfer sheet is sucked to the opening forming surface by performing suction from the opening suction path provided on the opening forming surface,
Next, the transfer plate does not move undesirably even when the holding plate is moved forward toward the opening forming surface and suction from the opening surface suction path is stopped, and the transfer is performed when the inside of the cavity is decompressed. A gap between the opening forming surface and the pressing plate is secured between the opening forming surface and the pressing plate so that the sheet can slide on the opening forming surface without resistance and stick to the inner surface of the cavity.
After stopping the suction from the opening surface suction path, a core mold having a convex portion is inserted into the cavity, and the transfer sheet is extended at the tip of the convex portion while sliding the surface of the mold. And push it into the cavity,
The inside of the cavity is decompressed, and the transfer sheet is sucked in while further sliding the surface of the mold, and is closely adhered to the inner surface of the cavity,
An in-mold molding method characterized in that the mold is closed with the transfer sheet in close contact with the inner surface of the cavity, and then molten resin is injected into the cavity. A surface having a resin substrate sheet that is highly stretchable at room temperature and a pattern ink layer that is formed on the surface of the substrate sheet and that is highly stretchable at room temperature, and on which the pattern ink layer is formed The surface on the opposite side is highly slidable,
The base sheet has an elongation rate of 200% or more at normal temperature and an elastic recovery rate of 40% or less at 60% elongation.
The dynamic friction coefficient on the surface of the base sheet opposite to the surface on which the design ink layer is formed is 4.0 or less, and
The transfer sheet, wherein the resin constituting the base sheet has a melting point of 120 ° C. or higher.   A resin molded product formed by using the method according to claim 1.

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