JP2013248851A - Base film for transfer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base film for transfer on one surface of which an ink layer to be transferred to a transfer object is printed, with which a desired molding can be obtained without causing breakage of a transfer film even if the transfer film is made to follow a three-dimensionally molded transfer object when vacuum press thermal transfer is carried out.SOLUTION: A base film for transfer 2 satisfies following (a) to (c). (a) A melting point is 161°C or higher, (b) a Young's modulus is 350 MPa or less, and (c) a ratio (MD/TD) of a Young's modulus in a direction MD of the film to a Young's modulus in a direction TD of the film satisfies 0.95<MD/TD<1.05.

Description

  The present invention relates to a transfer substrate film used for transferring an ink layer such as a pattern to a three-dimensionally transferred object such as a cover case of a mobile phone or an interior panel of a car by a vacuum pressure thermal transfer method. It is.

  Conventionally, a hydraulic transfer method is known as a method for transferring a design to a three-dimensionally formed transfer target having a complicated three-dimensional shape. This water pressure transfer method is a method in which an ink layer serving as a design is floated on the surface of the water, and this ink layer is attached to the surface of a transfer medium for transfer. However, the hydraulic transfer method has a problem that transfer accuracy is low and it is difficult to express a high degree of design.

  As a method for solving this problem, a vacuum pressure thermal transfer method is used. As a substrate film for transfer used in this vacuum pressure thermal transfer method, it is excellent in releasability of the ink layer at the time of transfer, has a higher melting point than polyethylene resin, and has flexibility. Copolymer) has been used (see Patent Document 1).

JP 2001-80292 A

  However, although the polypropylene resin described in Patent Document 1 is flexible in a high temperature atmosphere, it is inferior in heat resistance. Therefore, let the transfer film follow the three-dimensionally transferred object. As a result, a satisfactory molded product was not obtained by breaking.

The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a transfer base film that can solve the above problems.
The inventors of the present invention have solved the above-mentioned problems by using a transfer substrate film under predetermined conditions.
That is, the transfer substrate film according to the present invention is a transfer substrate film in which an ink layer transferred to a transfer object is printed on one surface, a melting point of 161 ° C. or higher, a Young's modulus of 350 MPa or less, The relationship between the Young's modulus in the MD direction and the Young's modulus in the TD direction (MD / TD) is 0.95 <MD / TD <1.05.

Here, the yield point load of the transfer base film may be 6.0 N / cm or more.
Furthermore, the transfer base film may be composed of 70 to 50% by weight of homopolypropylene and 30 to 50% by weight of a propylene-based elastomer having a melting point of 140 to 170 ° C.
Further, an uneven structure may be formed on at least one surface of the transfer base film.

According to the present invention, as a transfer base film for printing a high-precision pattern such as a wood grain pattern, a transfer base film that is difficult to tear and has an appropriate tensile strength that does not unnecessarily stretch, can be obtained. Is provided.
In particular, in printing processing of high-accuracy patterns, it has an appropriate tensile strength, does not require a carrier for the support layer, and has an appropriate flexibility (elongation-followability to the shape of the transferred object) and heat resistance during transfer.

(A) is a schematic diagram showing a substrate film for transfer according to the present invention. (B) is a schematic diagram which shows the transfer film of the state which provided the ink layer in the base material film for transfer of (a). It is a figure explaining the process in the case of transferring by the vacuum pressure thermal transfer method. It is the figure which showed the manufacturing process of the base film for transcription | transfer of double-sided satin by T die-cast method. It is a figure which shows the formation process of the ink layer to the base film for transfer. It is a figure which shows the flow of manufacture of a molded object. It is a perspective view of the to-be-transferred body used for transfer of a transfer film. It is a figure which shows the surface of the molded object obtained by transcribe | transferring to a to-be-transferred body.

Hereinafter, embodiments of the transfer base film according to the present invention will be described.
The transfer base film 2 (see FIG. 1 (a)) according to the present invention is a part of a transfer film 1 used for makeup of a three-dimensional object to be transferred such as a cover case of a mobile phone or an interior panel of a car. It functions as a base material for the ink layer 3 (see FIG. 1B).
The substrate film for transfer 2 according to the present invention is one in which the ink layer 3 transferred to the transfer medium is printed on one surface, and (a) the melting point is 161 ° C. or higher, and (b) the Young's modulus is 350 MPa or less, (c) The relationship between the Young's modulus in the MD direction and the Young's modulus in the TD direction (MD / TD) satisfies 0.95 <MD / TD <1.05.

<Melting point of substrate film for transfer>
If the melting point of the transfer base film 2 is 161 ° C. or higher, the transfer film 1 is not broken or melted during the heat treatment by the vacuum pressure thermal transfer method performed under the conditions of 2 to 10 atm and 100 to 140 ° C., Transcription is possible. When the transfer substrate film 2 has a melting point of less than 161 ° C., the transfer film 1 is torn or melted during the heat treatment for transfer under the same conditions, and transfer cannot be performed.

  About the melting | fusing point of the base film 2 for transfer, in the range of 161 degreeC or more, by setting to melting | fusing point higher than the temperature conditions at the time of the transfer set according to the heat-resistant temperature of the to-be-transferred body 9 (refer FIG. 6). The transfer film 1 is not torn or melted during transfer.

  As shown in FIG. 1B, the transfer film 1 is obtained by providing the transfer base film 2 with the ink layer 3, and therefore has substantially the same melting point as that of the transfer base film 2.

  The melting point of the transfer substrate film 2 is preferably adjusted by the blending ratio of a homopolymer having a melting point higher than that of the copolymer.

<Young's modulus of substrate film for transfer>
The Young's modulus (MPa) of the transfer base film 2 is preferably 350 MPa or less. Furthermore, it is preferable that it is 110-350 MPa.

  When the Young's modulus is 350 MPa or less, the transfer film 1 extends appropriately at the time of transfer, so that the ink layer 3 can be transferred to the transfer target 9.

  When the Young's modulus (MPa) of the transfer base film 2 is greater than 350 MPa, the transfer film 1 does not extend by the transfer under the above conditions of the transfer film 1 and cannot be transferred cleanly.

  The Young's modulus of the transfer base film 2 can be adjusted by the resin configuration and the blending ratio (% by weight) thereof.

  Regarding the relationship (MD / TD) of the Young's modulus in the MD direction (film flow direction) and TD direction (film width direction) of the transfer base film 2, it should be 0.95 <MD / TD <1.05. For example, the pattern can be transferred cleanly without distortion. On the contrary, if it is out of the above range, the pattern is distorted in one direction at the time of transfer, and the transferred pattern of the molded body 5 (see FIG. 7B) is not clean.

  Here, the Young's modulus in the MD direction and the TD direction of the transfer base film 2 can be adjusted by stretching in one direction (MD direction or TD direction) during the manufacture of the transfer base film 2. The Young's modulus relationship (MD / TD) of the transfer base film 2 can be set to 0.95 <MD / TD <1.05.

<Yield point load>
When the yield point load of the transfer base film 2 is 6.0 N / cm or more, the transfer film 1 obtained by printing the ink layer 3 on the transfer base film 2 is wound into a roll. Wrinkles are less likely to occur.

  On the other hand, when the yield point load is less than 6.0 N / cm, when the ink layer 3 is printed in a state where a predetermined tension is applied to the transfer base film 2, the transfer base film 2 is necked. The pattern printed on the transfer base film 2 is easily distorted, and in this case, wrinkles are likely to occur when the printed transfer film 1 is rolled.

  Moreover, if the base film 2 for transfer is the said specific melting | fusing point, the specific Young's modulus, and the relationship (MD / TD) of a specific Young's modulus, the resin used for the base film 2 for transfer will be selected suitably. be able to.

  The substrate film for transfer 2 can be formed by a conventionally known method, and it is particularly preferable to form the film by a T-die casting method. When the film is formed by the T-die casting method, a film in which the relationship between the Young's modulus (MD direction) and the Young's modulus (TD direction) of the transfer base film 2 is 0.95 <MD / TD <1.05 is obtained. Is easy.

  Further, the surface of the transfer base film 2 may be provided with unevenness. For example, if an uneven structure such as a satin pattern or a pattern is provided on the back surface of the transfer base film 2 (the surface of the transfer film 1 opposite to the transfer side), the transfer base film 2 or transfer film When winding 1 in a roll shape, the blocking resistance and the slipperiness of the film can be improved.

  In addition, if the concavo-convex structure is provided on the surface of the transfer base film 2 on the side in contact with the ink layer 3, when the ink layer 3 is formed by printing, coating or the like, the ink or coating liquid is caused by a capillary phenomenon or the like. It is also possible to improve the transferability.

  Here, the concavo-convex structure may be provided on the transfer base film 2 in accordance with the printing position of the printing content (characters and designs) of the ink layer 3. The concavo-convex structure for improving the blocking resistance and the transfer property gives a favorable result that the concavo-convex of about 0.1 to 5 μm in the center line average roughness Ra (JIS B 0601).

  In addition, the method of forming irregularities on the surface of the transfer base film 2 is not particularly limited, but the transfer base film 2 may be formed separately from the film formation or after film formation.

[Transfer base film]
The transfer base film 2 may be any resin material as long as the above numerical conditions are satisfied. For example, homopolypropylene (hereinafter sometimes referred to as homo-PP) and propylene-based elastomer (hereinafter referred to as homo-PP). What is sometimes referred to as a PP-based elastomer) can be suitably used.
By doing in this way, even if it is not a multilayer film, even if it is a single layer, the peelability with respect to the ink layer 3 of the transfer film 1 can be made compatible. That is, a transfer film that can be transferred without providing a support layer is obtained.
Moreover, by using homo PP for the transfer base film 2, the releasability from the ink layer 3 is high.

<Homo PP>
Homopolypropylene suitably used for the transfer substrate film 2 is a homopolymer of propylene. By using this homopolypropylene, a transfer base film 2 having excellent heat resistance can be obtained. In the case of a polypropylene copolymer containing other monomers such as ethylene as a polymer structural unit instead of homopolypropylene, the melting point of the transfer base film 2 is lowered, and the heat resistance of the transfer base film 2 is lowered. It is not preferable. Further, by using homopolypropylene, the releasability from the ink layer 3 becomes high.

<PP elastomer>
On the other hand, the PP elastomer suitably used for the transfer substrate film 2 is preferably a copolymer obtained by copolymerization with propylene and one or more monomers selected from ethylene and α-olefin (excluding propylene). Specific examples of the α-olefin include butene, pentenehexene, heptene, octene, decene, dodecene and the like, and these random copolymers and block copolymers are preferable.

  A Ziegler-Natta catalyst, a metallocene catalyst, or the like is used for the production of the PP-based elastomer. The metallocene catalyst can precisely design the molecular structure of the polymer, can freely control the fine structure and copolymerization of the polymer, and can provide the heat resistance and flexibility required for the PP elastomer used in the present invention. it can. Accordingly, it is desirable that the PP elastomer used in the present invention is a PP elastomer produced using a metallocene catalyst.

  The melting point of the PP elastomer used for the transfer substrate film 2 is preferably 140 ° C to 170 ° C, and more preferably 150 ° C to 165 ° C. When the melting point of the PP-based elastomer is lower than 140 ° C., the transfer base film 2 contracts and deforms due to heat during vacuum pressure heat transfer, and the design ink layer 3 cannot be transferred cleanly.

  The melting point of the PP elastomer was measured using a differential scanning calorimeter (DSC) according to JIS K-7121. That is, after heating at a heating rate of 20 ° C. per minute to a temperature approximately 30 ° C. higher than that at the end of melting and maintaining for 10 minutes, cooling at a cooling rate of 10 ° C. per min. The apparatus was then stabilized and heated at a heating rate of 10 ° C. per minute to a temperature about 30 ° C. higher than the end of the melting peak (endothermic peak), and the endothermic peak temperature was taken as the melting point.

  The PP elastomer preferably has a shore A hardness of 65 to 90. The Shore A hardness of the PP-based elastomer was measured in accordance with ASTM D2240.

  The MFR of the PP elastomer is preferably 2 g / 10 min to 50 g / 10 min. If the MFR is less than 2 g / 10 min, the melt viscosity is too high and extrusion molding becomes difficult. When MFR exceeds 50 g / 10 min, it becomes difficult to obtain a film having a uniform thickness because the melt viscosity is too small.

  As described above, the PP-based elastomer resin is not particularly limited as long as it satisfies the above physical properties. For example, a commercially available resin may be used. As the commercially available PP-based elastomer, “Tuffmer” (registered trademark) or the like can be suitably used, but the present invention is not limited thereto.

  The blending ratio (% by weight) of the homo PP and PP elastomer in the transfer base film 2 is preferably homo PP: PP elastomer = 70-50: 30-50. By setting the blending ratio, a transfer base film 2 excellent in heat resistance and flexibility can be obtained.

  The thickness (μm) of the transfer base film 2 can be appropriately selected according to the use such as the shape of the transfer target 9 to be transferred. It is preferable to set it as 30 micrometers-150 micrometers from the relationship of a moldability. When the thickness of the transfer base film 2 is less than 30 μm, it is difficult to form the transfer base film 2 because it is thin, and when it exceeds 150 μm, the transfer base film 2 satisfying flexibility is formed. I can't.

  In addition, when the above-mentioned homo-PP and PP-based elastomer are used, the transfer base film 2 satisfies the flexibility and peelability with a single layer without providing a support layer made of urethane-based resin or the like. is there.

(Transfer film)
The transfer film 1 includes an ink layer 3 and a transfer base film 2 according to the present invention. The transfer film 1 is used for transferring a design such as a wood grain pattern or characters to the transfer body 9.

<Method for producing transfer film 1>
The transfer film 1 is manufactured by the process of forming the transfer base film 2 by the above-described T die casting method, and then the process of forming the ink layer 3 on one surface of the transfer base film 2. The
<Ink layer 3>
The ink layer 3 can be provided by a conventionally known method such as gravure printing, offset printing, and inkjet printing. Moreover, according to a use, a grain pattern, a stone pattern, a cloth pattern, a tile tone pattern, a brick tone pattern, a leather pattern, a character, a geometric pattern etc. can be used for a design.

  A known ink can be used for the ink layer 3 (see FIG. 1), which is a design, and includes a vehicle composed of a colorant such as a pigment or a dye and a binder. Resin used in binder is cellulose derivative, styrene resin, styrene copolymer resin, acrylic resin, methacrylic resin, rosin ester resin, polyvinyl acetate resin, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polyester resin, polyurethane One or more of a resin, a butyral resin, and a polyamide resin can be used. In addition, as the colorant, inorganic pigments such as titanium white, carbon black, dial, chrome lead and ultramarine, organic pigments such as aniline black, quinacridone, isoindolinone and phthalocyanine blue, or other dyes can be used.

[Transfer]
The transfer target 9 (see FIG. 6) to which the ink layer 3 of the transfer film 1 is transferred is not particularly limited. For example, a transfer body made of a resin such as a polypropylene resin, a vinyl chloride resin, a phenol resin, an ABS resin, a polyethylene terephthalate resin, or a polycarbonate resin is particularly preferable.

  Furthermore, the shape of the transfer target 9 may be a flat plate, a curved plate, a rod-shaped body, a three-dimensional object, or the like. In addition to the flat surface, the transferred surface may have a concavo-convex structure on the surface. Even a surface having a concavo-convex structure as shown in FIG. 6 can be transferred without tearing or the like (see examples described later).

[Transfer method]
A method for transferring a pattern onto the surface of the transfer target 9 using the transfer film 1 according to the present invention will be described.

  The transfer method in the present invention is characterized in that the steps of the vacuum pressure thermal transfer method and the peeling step of the transfer base film 2 are performed in this order.

<Process of vacuum pressure thermal transfer method>
The vacuum-pressurized thermal transfer process is a method of transferring the ink layer 3 as a pattern onto the surface of the transfer target 9 using the transfer film 1 as shown in FIGS.

  In the vacuum pressure thermal transfer process, a transfer device as shown in FIG. 2 is used. This transfer apparatus is configured around the upper and lower chambers 6 and 7.

  The upper chamber 6 is driven up and down by a driving device 8B. A plurality of heaters H are provided on the inner upper surface of the upper chamber 6. On the other hand, a support base 10 is disposed in the lower chamber 7. The support base 10 is driven up and down by the drive device 8A. The upper chamber 6 and the lower chamber 7 are connected to a vacuum pump 12, a solenoid valve 4, a compressed gas cylinder 11, and the like as pressure control means.

Next, the steps of the vacuum pressure thermal transfer method of the ink layer 3 using this transfer device will be described.
First, as shown in FIG. 2A, the transfer body 9 is set on the support base 10. Next, the transfer film 1 is set above the transferred body 9 so that the ink layer 3 faces the transferred body 9. An adhesive (not shown) is applied to the surface of the ink layer 3 or the transfer target 9.

  Next, as shown in FIG. 2B, the upper chamber 6 is lowered by the driving device 8B and brought into close contact with the lower chamber 7, and the chambers 6 and 7 are sealed.

  Then, the transfer base 9 is brought into contact with the transfer film 1 by raising the support base 10 by the driving device 8 </ b> A and pushing up the transfer target 9 toward the transfer film 1.

  Subsequently, the vacuum pump 12 is operated to depressurize the space S in the upper chamber 6 and the lower chamber 7 to a vacuum state. Thereafter, the inside of the upper chamber 6 is returned to atmospheric pressure or is brought into a pressurized state, so that the transfer film 1 wraps around to the details of the transfer body 9, and the transfer film 1 enters the transfer body 9. In close contact.

Subsequently, the transfer film 1 is heated by operating the heater H so that the upper and lower chambers 6 and 7 are heated to 100 to 140 ° C., and the upper chamber 6 is pressurized to 2 to 10 atm.
At this time, the surface of the ink layer 3 of the transfer film 1 or the surface of the transferred body 9 is adhered by an adhesive or the like, and the surface of the ink layer 3 of the transfer film 1 adheres to the transferred body 9, substantially. The ink layer 3 and the transfer base film 2 are transferred to the transfer target 9.

  Subsequently, the operation of the heater H is stopped and the inside of the upper chamber 6 and the lower chamber 7 is returned to the atmospheric pressure to cool the transfer target 9 and the transfer film 1.

<Transfer substrate film peeling process>
Finally, as shown in FIG. 2C, in the peeling process of the transfer base film 2, the upper chamber 6 is raised by the driving device 8B, and the transfer target 9 and the transfer film 1 are taken out. Then, the transfer base film 2 is peeled off from the ink layer 3. As a result, the ink layer 3 remains on the transfer medium 9 and is transferred. Further, the ink layer 3 is trimmed to complete the formed body 5.

[Post-processing]
In addition, on the surface of the molded body 5 after transfer, a conventionally known topcoat layer such as a transparent protective layer may be further formed by a coating method or the like in order to impart durability, design expression and the like as appropriate. Good.

[Use of molded body]
The molded body 5 obtained in the above process is an article having a transferred decorative surface having an uneven structure, particularly an article having an uneven structure such as a three-dimensional shape on the surface, and is used for various applications. For example, a mobile phone cover case, a car interior panel, a soap holder case, and a pen stand.

Examples of the transfer base film 2 according to the present invention will be described below.
[Example 1]
As shown in FIG. 3, the transfer base film 2 was formed by T-die casting.
Specifically, 60 wt% homo PP (density: 0.900 g / cm ³ , melting point: 160 ° C., MI: 2.1 g / 10 min) and 40 wt% PP elastomer (density: 0.868 g / cm 2). A resin composed of cm ³ , melting point: 141 ° C., MI: 6.0 g / 10 min, Shore A hardness: 82) is extruded from a T-die in a molten state, and nip-formed by a metal roller 13 and a silicon roller 14 having an uneven surface. Thus, a transfer base film 2 having a thickness of 70 μm on both sides was obtained.
Then, as shown in FIG. 4, the ink layer 3 was formed by gravure printing. Specifically, first, the cylinder 16 was rotated, and a part of the cylinder 16 was immersed in the ink reservoir 18 to fill the cells (plate surface depressions) with ink. Next, the doctor blade 15 was pressure-bonded to the plate surface, and unnecessary ink other than the ink clogged in the cells was scraped off.
Next, the transfer base film 2 is sandwiched between the pressure roller 19 and the cylinder 16, and the cylinder 16 is moved by the pressure roller 19 so that the ink is uniformly transferred to one surface of the transfer base film 2. The transfer base film 2 was pressed downward (open arrow), and ink was transferred from each cell of the cylinder 16 to the transfer base film 2. After the transfer, the transfer base film 2 was passed through the dryer 17 and dried to form the ink layer 3, whereby the transfer film 1 was obtained.
Using the obtained transfer film 1, the ink layer 3 serving as a design was transferred to the transfer body 9 in the vacuum pressurization thermal transfer process and evaluated.
The relationship between the melting point, Young's modulus, Young's modulus (MD / TD), yield point load and evaluation results of the transfer base film 2 are shown in Table 1 including other examples and comparative examples.

[Example 2]
A transfer film 1 was obtained in the same manner as in Example 1 except that the blending ratio of the resin was 65% by weight of homo-PP and 35% by weight of PP-based elastomer. Further, the image was transferred by the same transfer method as in Example 1.

[Example 3]
A transfer film 1 was obtained in the same manner as in Example 1 except that the thickness of the transfer base film 2 was 90 μm in Example 1. Further, the image was transferred by the same transfer method as in Example 1.

[Example 4]
Transferring in the same manner as in Example 1 except that the blending ratio of the resin in Example 1 was 50% by weight of homo PP, 50% by weight of PP elastomer, and the thickness of the transfer base film 2 was 100 μm. Film 1 was obtained. Further, the image was transferred by the same transfer method as in Example 1.

[Example 5]
A transfer film 1 was obtained in the same manner as in Example 1 except that the thickness of the transfer base film 2 was set to 80 μm in Example 1. Further, the image was transferred by the same transfer method as in Example 1.

[Example 6]
A transfer film 1 was obtained in the same manner as in Example 1 except that the blending ratio of the resin was 70% by weight of homo-PP and 30% by weight of PP-based elastomer. Further, the image was transferred by the same transfer method as in Example 1.

[Example 7]
Transferring in the same manner as in Example 1 except that the blending ratio of the resin in Example 1 was 50% by weight of homo PP, 50% by weight of PP elastomer, and the thickness of the transfer base film 2 was 80 μm. Film 1 was obtained. Further, the image was transferred by the same transfer method as in Example 1.

[Comparative Example 1]
In Example 1, homo PP was changed to random PP (ethylene content: 4.6 wt%, density: 0.890 g / cm ³ , melting point: 132 ° C., MI: 3.5 g / 10 min), and the resin mixing ratio was A transfer film 1 was obtained in the same manner as in Example 1 except that 70% by weight of random PP, 30% by weight of PP-based elastomer, and the thickness of the transfer base film 2 were set to 60 μm. Further, the image was transferred by the same transfer method as in Example 1.

[Comparative Example 2]
In Example 1, homo PP was changed to random PP (ethylene content: 4.6 wt%, density: 0.890 g / cm ³ , melting point: 132 ° C., MI: 3.5 g / 10 min), and the resin mixing ratio was A transfer film 1 was obtained in the same manner as in Example 1 except that 70% by weight of random PP, 30% by weight of PP-based elastomer, and the thickness of the base film for transfer 2 were set to 70 μm. Further, the image was transferred by the same transfer method as in Example 1.

[Comparative Example 3]
Transfer in the same manner as in Example 1 except that the blending ratio of the resin in Example 1 was 60% by weight of homo PP, 40% by weight of PP elastomer, and the thickness of the transfer base film 2 was 60 μm. Film 1 was obtained. Further, the image was transferred by the same transfer method as in Example 1.

[Test method, evaluation criteria, results consideration]
<Heat resistance>
(Measurement of melting point of substrate film for transfer)
In accordance with the method defined by JIS K 7121, measurement was performed with a differential scanning calorimeter (TA-50WS: manufactured by Shimadzu Corporation).
Measurement conditions: Sample charge: 6 mg, temperature increase, temperature decrease rate: 10 ° C./min

(Evaluation criteria for heat resistance of substrate film for transfer)
Judgment was made based on whether or not the film can be used as the transfer film 1 after the heat treatment at 140 ° C. in the vacuum pressure heat transfer process. Specifically, it was as follows.
“◯”: The transfer film 1 is not torn or melted during the heat treatment in the vacuum pressure thermal transfer process.
“X”: The transfer film 1 is torn or melted during the heat treatment in the vacuum pressure thermal transfer process.
If the transfer base film 2 is not heat resistant, the transfer itself is impossible if the pattern is damaged by the tearing or melting of the transfer film 1 under the heat treatment conditions of the heater H in the vacuum-pressurized thermal transfer process as described above. There is a case.
Therefore, it is necessary that the transfer base film 2 has appropriate heat resistance. About the heat resistance aptitude of each Example, after heating the base material film 2 for transfer to 140 degreeC, it was judged by whether it can be used as the base material film 2 for transfer.
The high heat aptitude of the transfer substrate film 2 leads to the fact that the lower layer of the ink layer 3 maintains the desired properties required for transfer even under heat treatment conditions during vacuum pressure thermal transfer. If the heat resistance of the material film 2 is high, the transferability tends to be good.
The heat resistance of each of the examples and comparative examples shown in Table 1 was determined based on this standard.

(Evaluation results for heat resistance)
By containing the homo-PP and the heat-resistant PP-based elastomer at predetermined concentrations, it was possible to sufficiently withstand the heat treatment conditions (about 140 ° C.) at the time of the vacuum pressure heat transfer (Example 1). ~ 7).
On the other hand, in the case of using random polypropylene (random PP) and a PP-based elastomer, none of the heat resistance suitability was obtained in contrast to Examples 1 to 7 (Comparative Examples 1 and 2).

<Printability>
(Measurement of yield point load)
According to the method specified by ASTM D 882, the tensile tester was used to measure at a speed of 500 mm / min.

(Evaluation criteria for printing process suitability)
The suitability for printing was determined by the yield point load of the transfer base film 2. When the yield point load is in an appropriate range (6.0 or more), the transfer film 1 does not extend too much during printing, and the printing process suitability is high.
The printing process suitability shown in Table 1 was determined from the measurement results obtained under the conditions of the above-described test method for each example and comparative example, and was determined based on whether or not wrinkles occurred after printing.
“◯”: No wrinkle was generated on the transfer film 1.
“×”: Wrinkles were generated on the transfer film 1.

(Evaluation results of printing process suitability)
Since the transfer base film 2 according to Examples 1 to 6 has a homo PP of 70 to 50% by weight, a PP elastomer of 30 to 50% by weight, and a thickness of 70 μm or more, the yield point load is 6.0. It became the above range, it was not extended too much at the time of a printing process, and all the printing process aptitudes were favorable (refer Table 1).
From this, the yield point load of the transfer base film 2 becomes 6.0 or more by containing the homo-PP and the PP-based elastomer at a predetermined ratio as in Examples 1 to 3. As a result, when the yield point load is 6.0 or more, the transfer base film 2 having good printing process suitability according to various printings can be obtained.

<Transferability>
(Measurement of Young's modulus)
According to the method prescribed by ASTM D882, the tensile tester was used to pull at a speed of 50 mm / min, and the stress-strain curve was obtained from the initial slope of the tensile test.

(Evaluation criteria for transfer aptitude)
Transferability is the ease of transfer when the ink layer 3 of the transfer film 1 is transferred to the transfer target 9. When the Young's modulus of the transfer film 1 is 350 MPa or less, the transfer film 1 is suitably stretched during transfer, so that three-dimensional transfer is facilitated. If the pressure is higher than 350 MPa, the transfer film 1 has a small extension during transfer and cannot be transferred clearly.
Further, if the Young's modulus relationship (MD / TD) is 0.95 <MD / TD <1.05, the pattern is less likely to be distorted during transfer, and the image can be clearly transferred. If it is in the other range, the pattern tends to be distorted in one direction at the time of transfer. In this case, the transferred pattern is not beautiful.
In each of the examples and comparative examples, no other layer is provided in addition to the ink layer 3, and the ink layer 3 itself is hardly involved in the Young's modulus of the transfer film 1. However, the characteristics of the transfer film 1 are almost the same.
Using a resin case (see FIG. 6) as the transfer target 9, transfer suitability was evaluated according to the following evaluation criteria.
“◯”: The pattern was transferred with good reproducibility.
“Δ”: A part of the pattern on the side part was slightly deformed, but could be transferred without any practical problem.
“×”: The pattern on the side surface was deformed, and transfer was defective.

(Evaluation result of transfer aptitude)
Further, in the example, as shown in FIG. 7A, the transfer film 1 tends to uniformly extend even on the curved surface of the corner portion, and the width of the grain pattern tends to be equally spaced. As shown in (b), the grain pattern was partially concentrated, and the grain pattern tended not to be equally spaced in the transverse direction.
In Comparative Example 1 and Comparative Example 3, the Young's modulus is 350 MPa or less, but it is out of the range of 0.95 <MD / TD <1.05. The transfer aptitude was “x”.

(Comprehensive evaluation)
As a comprehensive evaluation, the transfer base film 2 of Examples 1 to 3 was provided with particularly preferable properties based on a comprehensive judgment based on the evaluations of the respective aptitudes.

  As described above, the transfer base film 2 and the like according to the present invention have been described based on the embodiment and each example, but the specific configuration is not limited thereto, and each claim in the claims Design changes and additions are permitted without departing from the spirit of the invention according to the paragraph.

  In particular, as long as the transfer film 1 has a resin structure and ratio that satisfy the ranges of the melting point, Young's modulus, and yield point load, the transfer film 1 according to the present invention is not limited to the above-mentioned homo PP and PP elastomers. There is a high possibility of obtaining the action and effect during transfer.

DESCRIPTION OF SYMBOLS 1 Transfer film 2 Transfer base film 3 Ink layer 4 Electromagnetic valve 5 Molded body 6 Upper chamber 7 Lower chamber 8A, 8B Driving device 9 Transfer target 10 Support base 11 Compressed gas cylinder 12 Vacuum pump 13 Metal roller 14 Silicon roller 15 Doctor Blade 16 Cylinder 17 Dryer 18 Ink reservoir 19 Pressure roller H Heater

Claims (4)

In the transfer base film in which the ink layer transferred to the transfer target is printed on one surface, the transfer base film satisfies the following (a) to (c).
(A) Melting point is 161 ° C. or higher (b) Young's modulus is 350 MPa or less (c) The relationship between MD Young's modulus in MD direction and Young's modulus in TD direction (MD / TD) is 0.95 <MD / TD <1. 05   The transfer base film according to claim 1, wherein a yield point load is 6.0 N / cm or more. 70-50% by weight homopolypropylene,
The substrate film for transfer according to claim 1 or 2, comprising 30 to 50% by weight of a propylene-based elastomer having a melting point of 140 to 170 ° C.   The substrate film for transfer according to any one of claims 1 to 3, wherein an uneven structure is formed on at least one surface.