JP2018020531A - Method for producing vacuum molding sheet having good moldability and stability, and method for producing decorative product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a molding sheet that is a method for vacuum molding processing a resin sheet to produce a molding sheet which can suppress wrinkle and deflection of the molding sheet, sufficiently follows a mold and is excellent in moldability, and to provide a method for producing a decorative product.SOLUTION: There are provided a method for vacuum molding processing a resin sheet to produce a molding sheet which includes a vacuum suction step of the resin sheet on a mold at a mold temperature of 40-100°C, a step of stopping the vacuum suction and heating the resin sheet, and a vacuum suction step after the heating step, where the resin sheet exists in a temperature region in which such a temperature that a storage elastic modulus (E') measured at 10 Hz is 300 MPa is the mold temperature or lower by +130°C; and a method for producing a decorative product using the same.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a molded sheet having good moldability and stability, a method for producing a decorative article using the same, and a production apparatus.

  Conventionally, as a method for decorating the surface of communication equipment parts such as automobile interior parts and the case of mobile phones and personal computers, there is a simultaneous molding method using a sheet. In this method, a sheet composed of a base material, a decorative layer, and the like is placed in an injection mold, and after closing the mold, a molding resin is injected into the mold, and the sheet is placed on the surface of the resin molded product. A molded and simultaneously decorated molded product is obtained by bringing them into close contact with each other. In the above-mentioned simultaneous decoration method, it is general that the sheet is generally subjected to three-dimensional processing in advance along the cavity in a mold for injection molding before injecting the molding resin.

  As the above three-dimensional processing method, generally, after setting the sheet on the front surface of the cavity for injection molding, the vacuum forming processing method in which the sheet is brought into the cavity by sucking the air between the sheet and the cavity. Is used. Further, as this sheet, a polyethylene terephthalate-based sheet is often used from the viewpoint of moldability and heat resistance. Here, if the cavity has a complicated shape or the corner curve in the cavity is steep, the polyethylene terephthalate sheet generally has high rigidity, so that vacuum forming alone follows the cavity well. Hateful. Therefore, in order to make the sheet follow the cavity shape well, it is common to insert a heating plate or the like before vacuum suction and heat the sheet to soften it (Patent Document 1).

JP 2002-010343 A

Here, due to the structure of the injection molding machine, the sheet is generally installed vertically and heated. However, in the method described in Patent Document 1, there is a concern that when the sheet is softened by heating, the sheet bends due to gravity and cannot be stably and satisfactorily formed. Further, when the sheet is softened by heating, the sheet is wrinkled by heat, so that there is a problem that it is difficult to mold well.
Therefore, a vacuum processing method having excellent moldability and excellent stability during sheet heating has been demanded.

  As a result of intensive studies, the inventors have started vacuum suction of the resin sheet before heating, and by adhering the resin sheet to the cavity to some extent, once the vacuum suction is stopped and the resin sheet is heated It was discovered that wrinkles and sagging of the resin sheet can be suppressed.

That is, the present invention relates to the following [1] to [5].
[1] A method for producing a molded sheet by vacuum forming a resin sheet, the vacuum suction step of the resin sheet on a mold having a mold temperature of 40 ° C. to 100 ° C., and stopping the vacuum suction, While having the process of heating a resin sheet, and the vacuum suction process after this heating process, the temperature at which the storage elastic modulus (E ′) measured at 10 Hz is 300 MPa is the mold temperature + 130 ° C. A method for producing a molded sheet, which is present in the following temperature range.
[2] The method for producing a molded sheet according to [1], wherein the mold temperature is 80 ° C. or lower.
[3] The molded sheet according to any one of [1] or [2], wherein the resin sheet has a storage elastic modulus (E ′) measured at 10 Hz of 5000 MPa or less at a mold temperature. Method.
[4] Any of the above [1] to [3], wherein the resin sheet is a sheet having at least one layer containing a polyester polycondensate using at least terephthalic acid as a dicarboxylic acid and at least butanediol as a diol. A method for producing a molded sheet according to claim 1.
[5] After the resin sheet is vacuum-formed by the manufacturing method according to any one of [1] to [4], the mold is clamped and molten resin is injected into the mold, and the molded sheet is adhered to the resin surface. A method for producing a decorative product, characterized in that:

  In the vacuum processing method of the present invention, since a resin sheet is held by a cavity during heating by using a specific resin sheet, it is possible to suppress the deflection and wrinkle of the resin sheet due to heating. ADVANTAGE OF THE INVENTION According to this invention, the stability at the time of a heating can be provided and the vacuum processing method with a good moldability can be provided, The industrial value is high.

It is a figure which shows the measurement result of the storage elastic modulus (E ') of the resin sheet (PBT-type sheet | seat 1) used in Example 1. FIG. It is a figure which shows the measurement result of the storage elastic modulus (E ') of the resin sheet (PET-type sheet | seat 1) used in the comparative example 2.

Hereinafter, the present invention will be described in detail.
(Method for producing molded sheet)
After the resin sheet is set on the concave surface of the mold by the clamp member, the molded sheet of the present invention is subjected to a “vacuum suction process” and a “heating process” which will be described later, and then the mold concave part (hereinafter referred to as “cavity forming surface”). To form a three-dimensional shape so as to follow.

  The mold temperature in the production of the molded sheet is 40 ° C to 100 ° C. Within this temperature range, the molded decorative article can be easily taken out from the mold. From the standpoint of easy removal, the mold temperature is more preferably in the range of 40 ° C to 80 ° C.

<Vacuum suction process of the present invention>
In the vacuum suction process of the present invention, the space between the recess and the resin sheet in the molding die is sealed, and the resin sheet is made to follow the recess by exhausting from the vacuum suction hole and lowering the atmospheric pressure in the space. This is a stretching process. The atmospheric pressure in the space at this time may be less than 1 atm (= 101.3 kPa), and may be a reduced pressure condition, not necessarily a vacuum pressure. The pressure in the space is preferably a reduced pressure condition of 50 kPa or less, more preferably 10 kPa or less, and even more preferably 5 kPa or less. This atmospheric pressure is determined by the shape of the mold and the exhaust flow rate of the vacuum pump used.

  In the present invention, the vacuum suction of the resin sheet is started before heating to bring the sheet into contact with the cavity to some extent, and then the vacuum suction is stopped to heat the resin sheet, and the vacuum suction is started again. By starting the vacuum suction of the resin sheet before heating, the resin sheet is held by the cavity during heating, so that deflection and wrinkle of the resin sheet due to heating can be suppressed. Therefore, stopping and heating the vacuum suction in the resin sheet are preferably performed after the resin sheet is vacuum-sucked and the contact area between the resin sheet and the cavity becomes 10% or more of the surface area of the cavity, and is 20% or more. It is more preferable to carry out after that.

Also, by stopping the vacuum suction and heating the resin sheet, it is possible to maintain the sheet shape by reducing the pressure, but it is possible to suppress the heat being taken away by continuing the vacuum suction, so the temperature of the sheet surface increases. Easy and efficient In the present invention, the cavity surface area means the area of the concave surface of the mold for injection molding, that is, the area of the cavity surface in contact with the injected resin. Further, the contact area between the resin sheet and the cavity can be obtained by calculating and measuring the area where the resin sheet is in close contact with the portion of the cavity surface in contact with the injected resin, using a ruler. The ratio of the contact area between the resin sheet and the cavity can be calculated as “contact area between the resin sheet and the cavity” / “cavity surface area” × 100 (%). This can be controlled by the storage elastic modulus of the resin sheet described below under the mold temperature.

<Resin sheet heating process>
In the present invention, the heating step of the resin sheet includes a hot air generator, a plate heater in which nichrome wire is insulated with a heat-resistant mica plate, and the outer periphery is covered with stainless steel, a bonded steel plate, and the like, and a far infrared heater. Among them, a far-infrared heater is preferable because heating unevenness is small and an object at a distance is easily heated.
In the present invention, the heating temperature of the resin sheet is not particularly defined as long as the surface temperature of the resin sheet rises to within the mold temperature + 130 ° C., but the surface temperature of the heater is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. Preferably, 200 degreeC or more is more preferable. Moreover, from a viewpoint of preventing the thermal deterioration of a resin sheet, 400 degrees C or less is preferable and 300 degrees C or less is more preferable.

<Physical property rules for resin sheets>
In the present invention, a resin sheet having a temperature at which the storage elastic modulus (E ′) measured at 10 Hz is 300 MPa is in the temperature range of the mold temperature + 130 ° C. or less is used. In the present invention, since the resin sheet is vacuum-sucked before being heated and partially adhered to the cavity, the heat of the resin sheet is deprived by the cavity, and the resin sheet surface temperature is unlikely to rise when heated thereafter. However, if the resin sheet has the above storage elastic modulus, even when the resin sheet surface temperature rises only up to the mold temperature + 130 ° C., the resin sheet is sufficiently softened to follow the mold and is good. Can be molded. Although it is possible to raise the surface temperature of the resin sheet by raising the mold temperature, in this case, it is necessary to lower the mold temperature in order to take out the decorative product well after injecting the resin. The nature is bad. On the other hand, in the present invention, since the resin sheet is sufficiently softened by heating and good vacuum forming can be performed without increasing the mold temperature, productivity can be dramatically improved. It should be noted that the mold temperature is preferably 100 ° C. or less, and more preferably 80 ° C. or less, in order to satisfactorily remove the decorative product from the mold without lowering the mold temperature.

  The resin sheet preferably exists in a temperature range where the storage elastic modulus (E ′) measured at 10 Hz is 300 MPa, the mold temperature + 100 ° C. or less, and the storage elastic modulus measured at 10 Hz. More preferably, the temperature at which (E ′) is 300 MPa exists in the temperature range of the mold temperature + 50 ° C. or less.

  The storage elastic modulus (E ′) is one of physical quantities expressing viscoelasticity, and the measurement method is, for example, using a viscoelasticity measuring device or the like, for example, vibration frequency 10 Hz, strain 0.1%, temperature rise. The measurement is performed at an arbitrary temperature range at a speed of 3 ° C./min and a distance between chucks of 25 mm. Further, from the viewpoint of heat resistance, the lower limit value of the storage elastic modulus (E ′) measured at 10 Hz of the resin sheet is preferably 100 MPa or more in the temperature range of the mold temperature + 130 ° C. or less.

  In order to bring the resin sheet into close contact with the cavity to some extent by vacuum suction, the storage elastic modulus (E ′) at the mold temperature is preferably 5000 MPa or less. The storage elastic modulus (E ') at the mold temperature of the resin sheet is preferably 4000 MPa or less, more preferably 3000 MPa. The lower limit value of the storage elastic modulus (E ′) at the mold temperature is not particularly defined, but is preferably 200 MPa or more, and more preferably 500 MPa or more from the viewpoint of sheet handling properties.

  In order to set the storage elastic modulus of the resin sheet within the above range, in addition to using a resin sheet including a base material layer having the composition described later, an elastomer is added to the base material layer of the resin sheet. There are methods such as adjusting the crystallinity by adjusting the cooling conditions during film formation and adjusting the stretching conditions.

  Examples of the elastomer include polyolefin elastomers and polyester elastomers. Among these, a polyester elastomer is preferable from the viewpoint of compatibility with a polyester resin described later. Examples of the polyester elastomer include trade name Primalloy manufactured by Mitsubishi Chemical.

  In order to reduce the storage elastic modulus of the resin sheet, the cooling condition is to suppress the crystallization of the base material layer, for example, by changing the casting temperature during film formation from the glass transition temperature of the resin contained in the base material layer. In order to increase the storage elastic modulus of the resin sheet, for example, the casting temperature at the time of film formation is changed to the base material layer in order to promote crystallization of the base material layer. What is necessary is just to carry out slow cooling, such as making it the glass transition temperature or more of resin contained.

  In order to reduce the storage elastic modulus of the resin sheet, the drawing condition may be a low draw ratio, and in order to increase the storage elastic modulus of the resin sheet, the draw ratio may be increased. Here, in order to achieve the above storage elastic modulus, the base material layer in the resin sheet is preferably unstretched. Here, the term “non-stretched” means that no stretching treatment is performed on the formed base material layer.

<Usefulness as a decorative sheet>
Since the resin sheet of the present invention has the above-described physical properties, in the manufacturing method in which the vacuum suction is stopped and the resin sheet is heated, the resin sheet is partially adhered to the cavity. Even when the sheet surface temperature rises only up to the mold temperature + 130 ° C., the mold sufficiently follows the mold and can be molded satisfactorily. Therefore, it can be used for decoration using a mold having a sharp curve shape such that R at the corner of the mold is 5 mm or less. In particular, the present invention can also be used for decoration using a mold having a sharper curve shape such that R at the corner of the mold is 3 mm or less.

<Configuration rules of resin sheet>
Any resin sheet may be used as long as it has the above storage elastic modulus (E ′). The resin sheet used in the present invention may be composed of only the base material layer described later, or may be composed of a base material layer / functional layer in which a functional layer described later is laminated on the base material layer, but is colored. It is more preferable to use a base material layer / functional layer laminate structure because it easily imparts functions such as hard coat properties and reflectivity.

[Base material layer]
What is comprised with a thermoplastic resin is preferable, and it is preferable that this thermoplastic resin is a polyolefin-type resin or a polyester-type resin from a viewpoint of the softness | flexibility of a resin sheet, or a moldability. In particular, a polyester resin is preferable from the viewpoint of heat resistance and the surface adhesiveness of a decorative product.
Furthermore, as one method for setting the resin sheet to the above storage elastic modulus (E ′), among polyester resins, a polyester polycondensate containing at least terephthalic acid as a dicarboxylic acid and using at least butanediol as a diol. (Hereinafter, sometimes referred to as “PBT resin”) is preferably used. The content of the PBT resin in the base material layer is not particularly defined as long as the above storage elastic modulus (E ′) can be realized, but preferably contains 50 wt% or more of PBT resin, and contains 80 wt% or more. More preferred.

The PBT-based resin may contain isophthalic acid or hydrogenated dimer acid in addition to terephthalic acid as dicarboxylic acid and polytetramethylene ether glycol as diol in addition to butanediol for sheet flexibility. .
The method for producing the base material layer is not particularly defined, but film formation by an extrusion method is common.

  The base material layer may contain a resin such as a polyester elastomer, a pigment, a processing aid, and the like in addition to the PBT resin described above. The substrate layer itself may have a laminated structure or a single layer structure. Examples of the laminated structure include a PBT resin layer / PBT resin + pigment layer / PBT resin layer, a laminate of layers having different PBT resin contents, and the like. The layer ratio of the base material layer in the resin sheet is not particularly defined as long as the storage elastic modulus E ′ can be achieved, but is preferably 50% or more, more preferably 70% or more, with respect to the layer thickness of the entire sheet, 80 % Or more is more preferable. It may be 100%.

[Functional layer]
Examples of the functional layer include a release layer, a colored layer, a hard coat layer, an AR layer, an AG layer, an adhesive layer, and a heat resistant layer. Among these, only 1 type may be laminated | stacked on the base material layer, and 2 or more types may be laminated | stacked. The method for forming these layers is not particularly defined, but can be formed on the above-described base material layer by a known method such as coating.

The resin sheet used in the present invention may be composed of only the base material layer described later, or may be composed of a base material layer / functional layer in which a functional layer described later is laminated on the base material layer, but is colored. It is more preferable to use a base material layer / functional layer laminate structure because it easily imparts functions such as hard coat properties and reflectivity.
Further, in the case of producing a decorative article using the resin sheet of the present invention, when the resin sheet is used as a transfer sheet for in-mold molding, the resin sheet of the present invention is at least released as the functional layer described above. It becomes a laminated structure containing a layer. Even if it is a case where it manufactures a decorative article, when setting it as an insert molding method, the structure which does not contain the functional layer mentioned above may be sufficient as this sheet | seat.

  The laminated structure of the resin sheet used in the present invention includes only a layer containing a PBT resin, a layer containing a PBT resin / colored layer / adhesive layer, a layer containing a PBT resin / colored layer / hard coat layer / adhesive layer, etc. Is mentioned. According to this, after the resin sheet is vacuum-formed, insert molding can be performed in which the mold is clamped and the molten resin is injected into the mold, and the sheet is brought into close contact with the resin surface. Also, layers containing PBT resin / release layer / colored layer / adhesive layer, layers containing PBT resin / release layer / colored layer / hard coat layer / adhesive layer, layers containing PBT resin / release If the layer structure is one in which at least one release layer is inserted as a functional layer, such as a layer / hard coat layer / adhesive layer, etc., after the sheet is vacuum formed, the mold is clamped and the molten resin is injected into the mold. In-mold molding in which a hard coat layer or a colored layer is transferred to the surface can be performed.

  The preferred thickness of the resin sheet used in the present invention is preferably 200 μm or less, more preferably 150 μm or less in terms of the total thickness from the viewpoint of mold followability and cost. Further, from the viewpoint of handling properties and strength, the total thickness is preferably 10 μm or more, and more preferably 30 μm or more. When the resin sheet has a laminated structure, the thickness of the base material layer is preferably 180 μm or less, more preferably 150 μm or less, and further preferably 100 μm or less from the viewpoint of mold followability and cost. Moreover, from a viewpoint of handling property or intensity | strength, 5 micrometers or more are preferable, 10 micrometers or more are more preferable, and it is more preferable that it is 20 micrometers or more. Further, the thickness of each functional layer is preferably 50 μm or less, more preferably 30 μm or less, and further preferably 20 μm or less from the viewpoint of mold followability and cost. Moreover, 1 micrometer or more is preferable from a viewpoint of provision of sufficient functionality, and 2 micrometers or more are more preferable.

  Of these, among the functional layers, the release layer is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less from the viewpoint of moldability and cost. Further, from the viewpoint of releasability, 1 μm or more is preferable, and 1.5 μm or more is more preferable.

  Among these functional layers, the hard coat layer is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less, from the viewpoints of moldability and cost. Moreover, from a viewpoint of surface hardness, 1 micrometer or more is preferable and 2 micrometers or more are more preferable.

  Among these functional layers, the colored layer is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less from the viewpoint of moldability and cost. Moreover, from a viewpoint of coloring favorably, 1 micrometer or more is preferable and 1.5 micrometers or more are more preferable.

  Of these, among the functional layers, the adhesive layer is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less from the viewpoints of moldability and cost. Moreover, from an adhesive viewpoint, 0.1 micrometer or more is preferable and 0.5 micrometer or more is more preferable.

Further, from the same viewpoint, the total thickness of the functional layers is preferably 80 μm or less, more preferably 50 μm or less, and further preferably 30 μm or less. Moreover, 1 micrometer or more is preferable from a viewpoint of provision of sufficient functionality, and 2 micrometers or more are more preferable.
The method for forming these functional layers on the decorative sheet of the present invention is not particularly defined, but is generally formed by coating.

  The total thickness of the functional layer is preferably 50 μm or less, more preferably 30 μm or less, and further preferably 20 μm or less from the viewpoint of mold followability and cost. Moreover, 1 micrometer or more is preferable from a viewpoint of provision of sufficient functionality, and 2 micrometers or more are more preferable.

(Method for producing decorative products)
In the present invention, the method for producing a decorative product is such that after a resin sheet is vacuum formed to produce a molded sheet, the mold is closed and molten resin is injected into the mold to integrate the molded sheet on the resin surface. An in-mold method, in which a molded sheet is produced by vacuum forming a resin sheet and then the mold is closed and molten resin is injected into the mold to transfer only a part of the molded sheet to the resin surface. Law.

  In the above-mentioned insert method and in-mold method, the resin sheet is vacuum-molded to produce a molded sheet. After vacuum forming, the molten resin is injected as it is to produce a simultaneously molded decorative product. can do. In this case, since a molded sheet and a decorative product can be manufactured continuously in the same mold, production efficiency is high and preferable. On the other hand, using a different mold in advance, the resin sheet is vacuum formed to produce a molded sheet, which is inserted into the mold for injection molding, and then the mold is closed and melted in the mold. Resin may be injected.

<Injection resin>
If the injection resin used in manufacture of the decorating article of this invention is a thermoplastic resin, it will be used without a restriction | limiting. In particular, from the viewpoint of moldability and a small melting point difference from the resin sheet, for example, polycarbonate resin, polypropylene resin, ABS resin (acrylonitrile-butadiene-styrene copolymer synthetic resin) and the like are preferably used. Especially, since the polypropylene resin has a lower melting point than other resins, when the above-described PBT resin is used as the base material layer of the resin sheet, even when the heat-resistant layer is not provided as the functional layer, the resin at the time of injection is used. It is preferable because melting of the resin sheet can be prevented.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by these examples and comparative examples. In the following, the flow direction (take-off direction) at the time of manufacturing the sheet is described as MD, and the perpendicular direction thereof is described as TD.
[Evaluation method]
Various physical properties and the like were measured and evaluated as follows.

<Storage elastic modulus (E ')>
About each resin sheet used in Examples and Comparative Examples, a sample (vertical direction: 4 mm, horizontal direction: 60 mm) using a viscoelasticity measuring device manufactured by IT Measurement Co., Ltd., trade name “Viscoelastic Spectrometer DVA-200” Was measured by measuring the TD from 25 ° C. to 250 ° C. at a vibration frequency of 10 Hz, a strain of 0.1%, a heating rate of 3 ° C./min, and a gap of 25 mm. Moreover, the measurement result of the storage elastic modulus (E ') of the resin sheet (PBT-type sheet 1) used in Example 1 is shown in FIG. 1, and the storage elastic modulus of the resin sheet (PET-type sheet 1) used in Comparative Example 2 is shown in FIG. The measurement result of (E ′) is shown in FIG.

<Mold contact area ratio>
Using a mold that is 100 mm long × 100 mm wide × 5 mm deep, corner corner R is 1.8 mm, and the thickness of the molded product is 2 mm, a resin sheet is set on the cavity and vacuum suction is stopped. The ratio of the contact area between the resin sheet and the cavity to the cavity surface area at the start of heating was calculated as “the contact area between the resin sheet and the cavity” / “cavity surface area” × 100 (%). The cavity surface area was calculated by measuring the area of the concave surface of the mold for injection molding, that is, the area of the cavity surface in contact with the injected resin from the mold drawing. The contact area between the resin sheet and the cavity was calculated by measuring the area where the resin sheet was in contact with the injected resin on the cavity surface with a ruler.

<Heater temperature>
The heater surface temperature was measured with a contact thermometer. The heater temperatures in Examples 1 to 3 and Comparative Examples 1 and 2 were all 220 ° C.
<Resin sheet temperature>
The surface temperature of each resin sheet during heating with a heater was measured with a contact thermometer.

<Evaluation of stability during heating>
The sheet was evaluated as follows from the presence or absence of wrinkles and tarmi on the sheet during heating.
○: No wrinkles or tarmi ×: Wrinkles or tarmi occurred

<Evaluation of vacuum formability>
Using a mold with a length of 100 mm × width 100 mm × depth 5 mm, a corner R of 1.8 mm, and a molded product thickness of 2 mm, a resin sheet is set on the cavity, and vacuum suction and heating are performed. From the ratio of the contact area between the resin sheet and the cavity with respect to the cavity surface area after all the measurements were performed, the following judgment was made. A vacuum pump with an exhaust flow rate of 50 L / min was used for vacuum suction. The cavity surface area was calculated by measuring the area of the concave surface of the mold for injection molding, that is, the area of the cavity surface in contact with the injected resin from the mold drawing. The contact area between the resin sheet and the cavity was calculated by measuring the area where the resin sheet was in contact with the injected resin on the cavity surface with a ruler. From these, calculation was made as “the contact area between the resin sheet and the cavity” / “the surface area of the cavity” × 100 (%).
○: Contact area ratio is 80% or more ×: Contact area ratio is less than 80%

<Evaluation of injection moldability>
From the state of the sheet after injection molding, it was judged as follows.
○: No tearing, wrinkles, necking, etc. ×: There is tearing, wrinkles, necking, etc. PBT-based sheet 1 and PET-based sheet 1 which are resin sheets used in Examples and Comparative Examples are shown below.

<PBT-based sheet 1>
Extruded film-forming sheet having a thickness of 100 μm made of a polycondensate of terephthalic acid and butanediol (storage elasticity measured at a mold temperature (50 ° C.) of 1400 MPa and 10 Hz, measured at the mold temperature (50 ° C.). The temperature at which the rate (E ′) was 300 MPa was 75 ° C.).

<PET-based sheet 1>
Extruded film-forming sheet having a thickness of 50 μm made of a polycondensate of terephthalic acid and ethylene glycol (storage elastic modulus (E ′) measured at the mold temperature (50 ° C.) measured by the above-mentioned method at 4000 MPa and 10 Hz) The temperature at which the rate (E ′) becomes 300 MPa is 200 ° C.).

[Example 1]
The PBT sheet 1 is set as a resin sheet on the mold cavity adjusted to 50 ° C., the sheet is brought into close contact with the cavity to some extent by vacuum suction, and then the vacuum suction is stopped to evaluate the mold contact area ratio. did. Thereafter, the sheet was heated with an infrared plate heater having a surface temperature of 220 ° C., and the surface temperature of the sheet was heated to 120 ° C. Thereafter, vacuum suction was resumed while heating to obtain a molded sheet 1. Thereby, the sheet satisfactorily followed the cavity shape. Thereafter, the mold was clamped and PP resin was injected to obtain a decorative product 1. Each evaluation result is shown in Table 1.
[Example 2]
Molding sheet 2 was obtained in the same manner as in Example 1 except that the distance from the sheet of the infrared heater was adjusted and the surface temperature of the resin sheet was changed as shown in the table. Further, the molded sheet 2 was clamped and injected in the same manner as in Example 1 to obtain a decorative product 2. Each evaluation result is shown in Table 1.
[Example 3]
As a resin sheet, PBT sheet 1 is used as a base material layer, and as a functional layer, a release layer (thickness 2 μm), a hard coat layer (thickness 5 μm), a colored layer (thickness 2 μm), and an adhesive layer (thickness 1 μm) In this order, molding was performed in the same manner as in Example 2 except that a layer laminated by coating so that the total thickness of the functional layer was 10 μm was used, and a molded sheet 3 was obtained. Clamping and injection were performed in the same manner as in Example 2 except that this was used as a transfer sheet and polycarbonate was used as the injection resin, whereby a decorative product 3 was obtained. Each evaluation result is shown in Table 1.

[Comparative Example 1]
In Example 1, molding was performed in the same manner as in Example 1 except that vacuum suction was performed after the sheet was heated, and a molded sheet 4 and a decorative article 4 were obtained. Each evaluation result is shown in Table 1.
[Comparative Example 2]
Molding sheet 5 and decorative article 5 were obtained in the same manner as in Example 2 except that PET sheet 1 was used in place of PBT sheet 1 as the resin sheet. Each evaluation result is shown in Table 1. In addition, even if the temperature and position of the heater were adjusted, the sheet temperature could not be higher than this.

  Since the comparative example 1 heated before performing vacuum suction, the wrinkles and the tarmi generate | occur | produced in the resin sheet at the time of a heating. In addition, when vacuum suction is used, the adhesion to the mold is improved, but a defective appearance of the molded sheet, which seems to be caused by wrinkles that enter the resin sheet during heating, occurred during injection molding. In Comparative Example 2, since the temperature at which the storage elastic modulus (E ′) measured at 10 Hz is 300 MPa is high, the resin sheet is not sufficiently softened even when the resin sheet is heated in contact with the mold. The mold could not be followed well by vacuum forming.

Claims (5)

A method for producing a molded sheet by vacuum forming a resin sheet,
While having a vacuum suction step of the resin sheet on a mold having a mold temperature of 40 ° C. to 100 ° C., a step of stopping the vacuum suction and heating the resin sheet, and a vacuum suction step after the heating step,
The method for producing a molded sheet, wherein the resin sheet has a temperature at which a storage elastic modulus (E ′) measured at 10 Hz is 300 MPa in a temperature range of the mold temperature + 130 ° C. or less.   The method for producing a molded sheet according to claim 1, wherein the mold temperature is 80 ° C or lower.   The method for producing a molded sheet according to claim 1, wherein the resin sheet has a storage elastic modulus (E ′) measured at 10 Hz of 5000 MPa or less at a mold temperature.   4. The sheet according to claim 1, wherein the resin sheet is a sheet having at least one layer containing a polyester-based polycondensate using at least terephthalic acid as a dicarboxylic acid and at least butanediol as a diol. 5. A method for producing a molded sheet.   After the said resin sheet is vacuum-molded with the manufacturing method of any one of Claims 1-4, it clamps and inject | pours molten resin in a type | mold, It adheres a molding sheet to the resin surface, To make decorative items.

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