JP3319737B2 - Method of manufacturing decorative molded products at the same time - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a simultaneously-decorated molded article having an excellent appearance in which a cavity is sufficiently filled with a resin and the decorative sheet is not damaged.

[0002]

2. Description of the Related Art Conventionally, as a method of decorating the surface of a resin molded product, there is a simultaneous decorating method using a decorative sheet.
The simultaneous molding and decorating method includes a simultaneous molding and transferring method using a transfer material as a decorative sheet and an insert method using an insert material as a decorative sheet.

In the simultaneous molding transfer method, a transfer material having a transfer layer formed of a release layer, a pattern layer, an adhesive layer, etc. formed on a base sheet is sandwiched in a molding die, and a molten resin is injected into the die. This is a method in which, after cooling to obtain a resin molded product, a transfer material is adhered to the surface of the molded product, the base sheet is peeled off, and the transfer layer is transferred to the surface of the object to be transferred, thereby performing decoration.

[0004] In the insert method, an insert material in which a pattern layer or the like is formed on a base sheet is sandwiched in a molding die, a molten resin is injected into the die, and cooled to obtain a resin molded product. This is a method of decorating by bonding an insert material to the surface of a molded product.

[0005] The simultaneous molding transfer method and the insert method have a feature that a pattern can be formed even in a molded article having a shape in which it is difficult to directly form a pattern by a printing method.

[0006]

However, these simultaneous molding and decorating methods have a problem that the decorating sheet is partially damaged when the molten resin is injected.

That is, there is a pin point gate as a gate of a molding die. The use of a molding die having a pinpoint gate has the advantages that the gate marks on the molded product are small and inconspicuous, and the runner can be easily removed from the molded product. However, about 1 in the cylinder
The high-temperature molten resin heated to 70 to 260 ° C. flows through a small-diameter gate portion such as a pinpoint gate to generate frictional heat at the gate portion, thereby further increasing the temperature. By suddenly hitting the decorative sheet installed in the molding die with high pressure,
The adhesive layer, the design layer, the base sheet, and the like that constitute the decorative sheet are partially melted and scattered. In addition, if the gate diameter is small, the flow rate of the resin is hindered and the resin does not flow to the end of the molded product, and it is necessary to inject the resin with a higher pressure, so that the decorative sheet is more likely to be damaged. there were.

Further, as other gate types, there are a side gate, a film gate, and the like that require a gate treatment after molding but can inject a large amount of molten resin. When a molding die having such a relatively large gate diameter is used,
High-temperature molten resin heated to 170 to 260 ° C. in the cylinder will flow into the cavity at once in a large amount, and the adhesive layer of the decorative sheet will be melted and flown by the amount of heat of the molten resin. There has been a problem that the decorative sheet does not adhere to the molding resin or the decorative sheet itself is damaged by the calorific value of the molten resin.

When the distance between the decorative sheet and the gate is small, the impact of the high-temperature and high-pressure molten resin is more likely to occur.

As described above, the adhesive layer, the design layer, the base sheet, etc. of the decorative sheet are damaged by the heat and pressure of the molten resin at the time of injection, and the bonding failure, the flow of the design, the wrinkles of the decorative sheet, And the like, and there is a problem that a defect occurs in the appearance of the simultaneously decorated decorative molded product.

Therefore, the present invention solves the above-mentioned drawbacks and easily manufactures a molded simultaneous decorative molded article having an excellent appearance in which the resin is sufficiently filled in the cavity and the decorative sheet is not damaged. The purpose is to provide a way to:

[0012]

Means for Solving the Problems In order to achieve the above object, a method for producing a simultaneously decorated decorative molded article according to the present invention is constituted as follows.

That is, according to the method for manufacturing a simultaneously-decorated molded article of the present invention, a decorative sheet is placed in a mold having a cavity, a molten resin is injected into the mold, and the decorative sheet and the resin are combined. In the method for producing a simultaneously decorated decorative molded article to obtain an integrated molded article, when the projected area of the molded article is a (m ² ) and the number of gates of the mold is b (pieces), 0 <a / b ≦ 0.0
6 was established.

In the above invention, when an average cross-sectional area of the gate is c (mm ² ), 0 <a / bc ≦ 0.
Twelve relationships may be established.

In the above invention, the gate may be configured as a pinpoint gate.

In the above invention, the projected area is:
In the range of 0 <a ≦ 0.06 (m ² ), b = 1 may be satisfied.

In the above invention, the temperature of the molten resin may be 170 to 260 ° C.

In the above invention, the decorative sheet may be a transfer material or an insert material.

In the above invention, the adhesive of the decorative sheet may be a thermoplastic resin, and the softening point specified in ASTM D648 may be 50 to 140 ° C.

[0020]

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing the relationship between the simultaneously decorated and molded product and the projected area in the method for producing a simultaneously decorated and molded product of the present invention. In the figure, reference numeral 1 denotes a simultaneously molded and molded product, and a denotes a projection area.

In the method for manufacturing the simultaneously decorated decorative molded article 1 of the present invention, a decorative sheet is placed in a mold having a cavity, a molten resin is injected into the mold, and the decorative sheet and the resin are integrated. 0 <a / b ≦ in the manufacturing method of the simultaneously decorated decorative molded article 1 for obtaining a molded article, where the projected area of the molded article is a (m ² ) and the number of gates of the mold is b (pieces). This is a method in which the relationship of 0.06 is established.

When the decorative sheet is supplied by the decorative sheet feeding device attached to the movable mold, or when the decorative sheet is larger than the cavity area, the mold has a sleep-rate type mold structure. Is preferred. When the decorative sheet is smaller than or approximately equal to the cavity area, the present invention can be applied to a two-plate molding die structure.

In the present invention, a gate is a port through which a resin melted in a cylinder of a molding machine is injected into a cavity in a mold from a nozzle and flows into the cavity directly or through a runner, sprue or the like in the mold. The part which becomes. Gates are classified into pinpoint gates, side gates, film gates, and the like, depending on the shape and the position of the gate. The pinpoint gate is
Usually, the gate is circular. In this case, the cross-sectional area of the gate is πr ^{2 where the} gate radius is r (mm). In the case of a multipoint gate, the average value of the cross-sectional area of each gate is defined as the gate cross-sectional area c.

The projected area a (m ² ) of the molded product is the maximum area of the cavity in the direction perpendicular to the opening direction of the mold,
That is, this is the area of the simultaneously decorated decorative molded product 1 projected on a horizontal plane in the die-cutting direction (see FIG. 1).

Here, it is important that the relationship 0 <a / b ≦ 0.06 holds. That is, when the molten high-temperature resin is injected and filled into the cavity, the problem of damaging the decorative sheet mounted in the molding die is due to the speed, flow rate and flow in the cavity when the molten resin is injected. I found that it depends on ease. In addition, they have found that it depends on the flow rate and pressure of the molten resin per gate when the molten resin is injected. In particular, when the area to be filled with the molten resin per gate increases, a higher pressure must be applied to the molten resin and the flow rate per gate increases, so that the molten resin having a high pressure and temperature near the gate is required. It was found that a large amount touched the decorative sheet and damaged the decorative sheet.

More specifically, the projected area of the molded product is represented by a
When (m ² ) and the number of gates b (pieces) of the mold satisfy the above relationship, the decorative sheet is not damaged by the pressure or heat of the molten resin. As long as the molded article has some shape, a / b is not 0, that is, the projected area a is not 0. When a / b exceeds 0.06, the gate 1
Since the area to be filled with molten resin per piece increases, higher pressure must be applied to the molten resin, and the flow rate per gate also increases. However, there is a problem in that a large amount is touched and damaged.

When the projection area a is 0 <a (m ² ) ≦ 0.06, it is preferable to set the number of gates to 1, that is, to satisfy b = 1. This is because, in the simultaneous decorating method, when the projection area a is 0 <a (m ² ) ≦ 0.06, it is better to set the number of gates to 1 for a multi-point gate having two or more gates. This is because it is possible to prevent wrinkles from occurring in the decorative sheet due to a weld line that occurs in such a case.

In general, it is preferable that the distance between the decorative sheet and the gate is not close to the decorative sheet.

The temperature of the molten resin is 170 to 2
Preferably it is 60 ° C. If the temperature of the molten resin is lower than 170 ° C., the flow of the molten resin is deteriorated, and there is a possibility that a short-circuit may occur in a molded product or poor adhesion of the decorative sheet may occur. If the temperature of the molten resin exceeds 260 ° C., the resin may be burnt and the molded product may be colored, or carbonized, and the resin residue may remain in the cylinder. Further, the decorative sheet may be melted. The molten resin is melted in the cylinder, and is generally in a state higher by about 10 to 40 ° C. than the temperature indicated by the nozzle of the injection molding machine. Then, when the molten resin is injected into the mold via the nozzle, it is considered that there is a temperature drop of about 10 to 40 ° C. Therefore, the nozzle indicated temperature of the injection molding machine may be regarded as indicating the molten resin temperature immediately before the injection.

As the decorative sheet, a transfer material or an insert material can be used.

The transfer material comprises a base sheet provided with a transfer layer comprising a release layer, a design layer, an adhesive layer and the like.

As a material of the base sheet, it is used as a base sheet of a usual transfer material such as a resin sheet of polypropylene resin, polyethylene resin, polyamide resin, polyester resin, acrylic resin, polyvinyl chloride resin and the like. Things can be used. When the surface of the base sheet has fine irregularities, the irregularities are transferred to the transfer layer, so that the surface shape such as matting or hair alignment can be expressed.

When the transfer layer has good releasability from the base sheet, the transfer layer may be provided directly on the base sheet. In order to improve the releasability of the transfer layer from the base sheet, a release layer may be formed over the entire surface before providing the transfer layer on the base sheet.

The release layer is formed entirely on the base sheet or the release layer. The release layer is a layer that is peeled from the base sheet or the release layer and becomes the outermost surface of the transferred object when the base sheet is peeled off after the simultaneous transfer of molding. Examples of the material of the release layer include acrylic resin, polyester resin, polyvinyl chloride resin, cellulose resin, rubber resin, polyurethane resin, polyvinyl acetate resin, and the like, as well as vinyl chloride-vinyl acetate copolymer. It is preferable to use a resin or a copolymer such as an ethylene-vinyl acetate copolymer resin.
When the release layer requires hardness, a photocurable resin such as an ultraviolet curable resin, a radiation curable resin such as an electron beam curable resin, or a thermosetting resin may be selected and used. The release layer may be colored or uncolored. As a method for forming the release layer, there are a coating method such as a gravure coating method, a roll coating method, and a comma coating method, and a printing method such as a gravure printing method and a screen printing method.

The design layer is formed on the release layer, usually as a printing layer. As a material of the printing layer, a resin such as a polyvinyl resin, a polyamide resin, a polyester resin, an acrylic resin, a polyurethane resin, a polyvinyl acetal resin, a polyester urethane resin, a cellulose ester resin, and an alkyd resin is used as a binder. ,
It is preferable to use a coloring ink containing a pigment or dye of an appropriate color as a coloring agent. As a method for forming the printing layer, a normal printing method such as an offset printing method, a gravure printing method, or a screen printing method may be used. The printing layer may be provided entirely or partially depending on the design to be expressed.

The design layer may be composed of a metal thin film layer or a combination of a printing layer and a metal thin film layer. The metal thin film layer is for expressing metallic luster as a design layer, and is formed by a vacuum deposition method, a sputtering method, an ion plating method, a plating method, or the like. Depending on the metallic gloss color you want to express, aluminum,
Metals such as nickel, gold, platinum, chromium, iron, copper, tin, indium, silver, titanium, lead, and zinc, and alloys or compounds thereof are used. The metal thin film layer may be partially formed. When providing the metal thin film layer, a front anchor layer or a rear anchor layer may be provided in order to improve the adhesion between another transfer layer and the metal thin film layer.

The adhesive layer is for bonding each of the above-mentioned layers on an object to be transferred. As the adhesive layer, a heat-sensitive or pressure-sensitive resin suitable for the material of the material to be transferred is appropriately used. For example, when the material of the transfer object is an acrylic resin, an acrylic resin may be used. When the material to be transferred is a polyphenylene oxide / polystyrene resin, polycarbonate resin, styrene copolymer resin, or polystyrene blend resin, an acrylic resin, polystyrene resin, polyamide A system resin or the like may be used. Further, when the material of the transfer object is a polypropylene resin, chlorinated polyolefin resin, chlorinated ethylene-vinyl acetate copolymer resin, cyclized rubber, and coumarone indene resin can be used. As a method of forming the adhesive layer, a gravure coating method, a roll coating method, a coating method such as a comma coating method, a gravure printing method,
There are printing methods such as a screen printing method. It is also possible to form an adhesive layer by laminating adhesive sheets made of the above materials by a laminating method or the like.

Here, the resin constituting the adhesive layer of the decorative sheet is a thermoplastic resin, and preferably has a softening point defined by ASTM D648 of 50 to 140 ° C. When the softening point is in this range, the adhesiveness to the molten resin is excellent.

The configuration of the transfer layer is not limited to the above-described embodiment. For example, when a material having excellent adhesiveness to the transfer object is used as the material of the design layer, the adhesive layer is omitted. be able to. If the design layer requires concealment, a concealment layer may be provided. The concealing layer may be formed in the same manner as the design layer.

Next, a method of decorating the surface of a resin molded product as an object to be transferred by using the above-described transfer material and simultaneous molding transfer method by injection molding will be described.

First, a transfer material is fed into a molding die composed of a movable die and a fixed die. At this time, the sheet transfer material may be fed one by one, or a necessary portion of a long transfer material may be sent intermittently. When a long transfer material is used, it is preferable to use a feeder having a positioning mechanism so that the register between the design layer of the transfer material and the molding die coincides with each other. In addition, when the transfer material is intermittently fed, if the transfer material is fixed by the movable type and the fixed type after the position of the transfer material is detected by the sensor, the transfer material can always be fixed at the same position. This is convenient because no misalignment of the design layer occurs.

After the molding die is closed, molten resin is injected and filled into the die from a gate provided on the fixed die, and a transfer material is adhered to the surface of the transfer material simultaneously with the formation of the transfer object.

As the molten resin, a polystyrene resin,
General-purpose resins such as polyolefin resins, ABS resins, AS resins, and AN resins can be given. In addition, polyphenylene oxide polystyrene resin, polycarbonate resin, polyacetal resin, acrylic resin,
General-purpose engineering resins such as polycarbonate-modified polyphenylene ether resin, polybutylene terephthalate resin, polybutylene terephthalate resin, ultrahigh molecular weight polyethylene resin, polysulfone resin, polyphenylene sulfide resin, polyphenylene oxide resin, polyarylate resin, polyetherimide resin, A super engineering resin such as a polyimide resin, a liquid crystal polyester resin, or a polyallyl heat-resistant resin can also be used. Further, a composite resin to which a reinforcing material such as glass fiber or inorganic filler is added can be used.

After cooling the resin molded product as the transfer object,
Open the molding die and take out the resin molded product. Finally, the base sheet of the transfer material is peeled off. In this way, by transferring only the transfer layer to the molded article, a simultaneously decorated decorative molded article can be obtained.

In order to obtain an insert material, the following method may be used.

The insert material has at least a design layer on a base sheet. As the base sheet, the same sheet as that of the transfer material may be used. Further, it is preferable to use the same pattern layer as that of the transfer material. Also,
The same adhesive layer as that of the transfer material may be used.
Therefore, the insert material differs from the transfer material in that it does not have a release layer.

As described above, the insert material can be obtained. Next, a method of using the insert material will be described.

The insert material is placed between the core mold having the gate and the cavity mold having the concave portion by using an insert material feeding device or the like, and is fixed in or around the cavity mold by means such as a clamp. When the molding shape is deep drawing, the insert material may be heated and softened by a heat source, and may be closely attached to the surface of the cavity mold by vacuum suction from the cavity mold side. The cavity mold and the core mold are clamped to form a closed space between the insert material and the core mold. The molten resin is injected into this space. As the molten resin, the same resin as used in the case of molding the transfer material may be used.
If the cavity mold and the core mold are opened, a molded product in which the insert material and the molding resin are integrated can be obtained.

Further, insert molding can be performed as follows. First, the insert material is fixed to a preforming mold having a concave portion for deep drawing by means of a clamp or the like, and then the insert material is heated and softened by a heat source and vacuum-sucked from the preforming mold side to form a preforming mold. Adhere to the surface. Next, the vacuum suction is released, and the insert material is taken out of the preforming mold. In this way, a deep drawn insert material can be obtained. Next, the preformed insert material is placed between a core mold having a gate and a cavity mold having a concave portion for deep drawing, and is fixed in or around the cavity mold by means such as a clamp. Next, the cavity mold and the core mold are clamped to form a closed space between the insert material and the core mold. If the molten resin is injected into this space and the cavity mold and the core mold are opened, the insert material and the molding resin can be integrated.

[0051]

(EXAMPLE) A polyethylene terephthalate film having a thickness of 0.05 mm is provided with a transparent window at the center using a strong adhesive ink, and a pattern including a concealed color pattern and characters is provided around the window. A pattern layer is formed by gravure printing in eight colors to have a thickness of 0.07 mm.
Was obtained as a decorative sheet.

The decorative sheet is made up of a short side of 0.3 m and a long side of 0.4.
A wood grain panel having a rectangular shape of m was sandwiched in a mold of a sleep rate method, and insert molding was performed. The projected area of the wood grain panel as a molded product is 0.12m
² (a = 0.12). A gate having two circular pinpoint gates on the back surface of the panel was used (b = 2). The cross-sectional area of each pinpoint gate was 0.8 mm ² (c = 1.6). In this case, a / b = 0.06 and a / bc = 0.0375.

In the injection molding step, the acrylic resin heated and melted at 240 ° C. in the cylinder was injected into the mold through the gate to obtain a simultaneously decorated decorative molded product.

In the thus-formed simultaneously decorated molded article, the adhesive layer and the design layer of the decorative sheet were not damaged and the design did not collapse.

(Comparative Example) A decorative simultaneously molded article was obtained in the same manner as in Example except that the number of gates was set to 1 (b = 1, c).
= 0.8). In this case, a / b = 0.12, a / bc =
It was 0.15. In the simultaneously decorated decorative molded product obtained in this manner, the molten resin was not sufficiently filled in the cavity, and the molten resin could be filled into the product shape by increasing the injection pressure. Then, the design layer was melted and the design collapsed.

[0056]

Since the present invention employs the above-described configuration, the following effects can be obtained.

According to the method for producing a simultaneously molded decorative product of the present invention, a decorative sheet is placed in a mold having a cavity,
In a method for producing a simultaneously molded decorative product by injecting a molten resin into a mold to obtain a molded product in which the decorative sheet and the resin are integrated, the projected area of the molded product is a (m ² ), When the number of gates is b (pieces), the relationship 0 <a / b ≦ 0.06 holds, so that the resin is sufficiently filled in the cavity,
It is possible to easily obtain a molded simultaneous decorative molded article having excellent appearance without damaging the decorative sheet.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a relationship between a simultaneously molded and decorated product and a projected area in the method of manufacturing a simultaneously decorated and molded product of the present invention.

[Explanation of symbols]

 1 Simultaneous decorative molding a Projected area

Claims (7)

(57) [Claims] A decorative sheet is placed in a mold having a cavity, a molten resin is injected into the mold, and a molded article in which the decorative sheet and the resin are integrated is obtained. In the manufacturing method, when the projected area of the molded product is a (m ² ) and the number of gates of the mold is b (pieces), 0 <a / b ≦ 0.0
6. A method for producing a simultaneously decorated decorative molded product, wherein the relationship of 6 is satisfied. 2. The method according to claim 1, wherein a relationship of 0 <a / bc ≦ 0.12 is satisfied when an average sectional area of the gate is c (mm ² ). 3. The method according to claim 1, wherein the gate is a pinpoint gate. 4. The projection area is 0 <a ≦ 0.06 (m ² )
The method for producing a simultaneously decorated decorative molded product according to any one of claims 1 to 3, wherein b = 1 is satisfied in the range described above. 5. The method for producing a simultaneously decorated decorative molded product according to claim 1, wherein the temperature of the molten resin is 170 to 260 ° C. 6. The method according to claim 1, wherein the decorative sheet is a transfer material or an insert material. 7. The adhesive of the decorative sheet is a thermoplastic resin, and has a softening point defined by ASTM D648 of 50 to 1.
The method for producing a simultaneously decorated decorative molded product according to any one of claims 1 to 6, which is at 40 ° C.