JP3325871B2 - 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 a decorative sheet is not wrinkled or 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, in these simultaneous molding and decorating methods, there is a problem that when the molten resin is injected, the decorative sheet is wrinkled or partially damaged. Was.

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 60 to 280 ° C. flows through a small-diameter gate portion such as a pinpoint gate to generate frictional heat at the gate portion, thereby increasing the temperature. By suddenly hitting the decorative sheet installed in the molding die with high pressure,
The decorative sheet may be wrinkled, or the adhesive layer, the design layer, the base sheet, and the like that constitute the decorative sheet may be 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 wrinkled or damaged. There was a problem that it was easy to do.

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,
The high-temperature molten resin heated to 160 to 280 ° C. in the cylinder will flow into the cavity in large quantities at once, and the decorative sheet will wrinkle or the adhesive layer of the decorative sheet will be heated by the amount of heat of the molten resin. There has been a problem that the decorative sheet cannot be adhered to the molding resin due to being melted and flown, or the decorative sheet itself is damaged by the heat 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 pattern 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, resulting in poor adhesion, flow of the pattern, wrinkling of the decorative sheet, melting 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.

[0011] Accordingly, the present invention is to provide a simultaneously-decorated molded article having an excellent appearance in which the above-mentioned drawbacks are eliminated, the resin is sufficiently filled in the cavity, and the decorative sheet is free from wrinkling and damage. It is an object to provide a method for easily manufacturing.

[0012]

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

That is, according to the method of manufacturing a simultaneously decorated decorative 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 molded decorative product to obtain an integrated molded product, the mold has a gate diameter of a (mm), AST
Test temperature T in the test method specified in MD1238
(° C.), when the melt flow rate at the pressing force P (N) of the piston is b (g / 10 min), 1 × 10
^It was configured such that the relationship of ⁻⁵ ≦ b / (T × P) and 0.25 ≦ a × b were both satisfied.

In the above invention, the gate may be a pinpoint gate having a gate diameter of 0.5 to 5 mm.

In the above invention, the test temperature T
However, you may comprise so that it may be 160-280 degreeC.

Further, in the above invention, the decorative sheet may be configured to be a transfer material or an insert material.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail.

[0018] In the method for producing a simultaneously decorated decorative molded article according to the present invention, a decorative sheet is placed in a mold having a cavity,
Injection of a molten resin into a mold to obtain a molded article in which a decorative sheet and a resin are integrated, a method for manufacturing a simultaneously-decorated molded article, wherein the gate diameter of the mold is a (mm) and ASTM D12
The melt flow rate at the test temperature T (° C.) and the pressing force P (N) of the piston in the test method specified in 38 is b (g).
/ 10 min), 1 × 10 ⁻⁵ ≦ b / (T ×
P) and 0.25 ≦ a × b.

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 molding 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, a 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, it is circular, in which case the gate diameter refers to the diameter of the gate. In addition, even if a pinpoint gate has an elliptical or other deformed shape for some reason, or if the shape of a gate such as a side gate or a film gate is not circular, the average of the minimum inner diameter and the maximum outer diameter of the gate is averaged. Is the diameter. When the shape of the gate is rectangular, the diameter is the average of the diagonal line and the short side. When there are multiple gates, the average of the gate diameters is used as the gate diameter. In case of pinpoint gate, gate diameter is 0.5 ~
Preferably it is in the range of 5.0 mm. The gate diameter is 0.
If it is less than 5 mm, the molten resin solidifies at the gate portion, and in most cases, the molding resin is insufficiently filled. On the other hand, if the gate diameter a exceeds 5.0 mm, the labor of the gate cutting work becomes large. In particular, there is no insufficient filling, the decorative sheet is not easily damaged, and the gate diameter at which the gate is easily cut is 0.8 to 2.0 mm.

The molten resin is not particularly limited as long as it satisfies the condition of claim 1, but is not limited to ABS resin, A
S resin, PP resin, PC resin, PS resin, PMMA resin, PE resin, PBT resin, PET resin, various thermoplastic elastomer resins, and the like can be used. Here, the term “main component” means that these resins are contained in the molten resin in an amount of 51% by weight or more.

The AS resin generally refers to a copolymer resin containing acrylonitrile / styrene as a component, and the ABS resin generally refers to a copolymer resin containing acrylonitrile / styrene / butadiene as a component. However, butadiene as a rubber component is thermally dispersed in the AS resin. May be contained.

Although these are generally used alone, they can also be used as a polymer alloy or a mixture with other resins. For example, polypropylene (PP) resin and polyethylene (PE) resin, polypropylene (PP) resin and olefin rubber, polycarbonate (PC) resin and polybutylene terephthalate (PB)
T) resin, ABS resin and polycarbonate (PC) resin, polycarbonate (PC) resin and polyamide (P
A) Polymer alloys or mixtures of resins, ABS resins and vinyl chloride resins, polyester thermoplastic elastomer resins and polyurethane thermoplastic elastomer resins can be used. The mixing ratio of these components is not particularly limited.

In addition, a resin filler, a coloring agent, and the like can be contained in a range where the total weight other than the main component is 49% or less.

As the filler, an inorganic powder filler such as silica and talc and a fibrous filler such as glass fiber, carbon fiber and metal fiber such as stainless steel can be used. However, these fillers are used to increase the physical strength of the molded product, but work in a direction that makes the melt flow worse (decrease), so that wrinkles are formed in the simultaneous decorative decorating method. It is preferable to keep the amount as small as possible for generation.

The melt flow rate (MFR), also called the melt index (MI), is an index of the ease of resin flow, and when it is in a molten state in a mold, it can be determined that the larger the value, the easier it is to flow.

The melt flow rate is as per ASTM D12
The amount of resin extruded from the orifice at a constant temperature and pressure using an extrusion type plastometer is expressed in terms of grams per 10 minutes, and is expressed in g / g. It is a numerical value indicated in units of 10 min.

In general, a resin having a low melt flow rate has a poor fluidity, and when used in the simultaneous molding and decorating method, the resin is easily stretched due to a high temperature, and the resin in the cavity is liable to be stretched due to friction in the cavity. When the decorative sheet is stretched, a problem that the decorative sheet is excessively wrinkled on the end face of the mold easily occurs.

Here, the gate diameter of the mold is a (mm), A
Test temperature T in the test method specified in STM D1238
(° C.), when the melt flow rate at the pressing force P (N) of the piston is b (g / 10 min), 1 × 10
It is important that the relations ⁻⁵ ≦ b / (T × P) and 0.25 ≦ a × b hold. That is, when the molten high-temperature resin is injected and filled into the cavity, wrinkles and damages to the decorative sheet mounted in the molding die are caused by the flow rate of the molten resin and the flow in the cavity. I found that it depends on ease. In particular, when the molten resin is melted in the cylinder and injected at a temperature of 190 to 260 ° C., the flow rate at which the molten resin is injected depends on the gate diameter, and the flow rate in the cavity is the flow rate of the resin flowing through the cavity. It turned out to depend on ease.

More specifically, the mold gate diameter a (m
m), the test temperature T (° C.) according to the test method specified in ASTM D1238, and the melt flow rate b (g / 10 min) at the pressing force P (N) of the piston satisfy the above-mentioned relationship, whereby the decorative sheet is obtained. Are not wrinkled or damaged by the pressure or heat of the molten resin. b
If / (T × P) is not more than 1 × 10 ^−5, it is necessary to set a considerably high test temperature or a high piston pressure to fill the cavity with the molten resin. Unless the decorative sheet is extremely excellent in heat resistance, it may be melted. If a × b is not more than 0.25, the molten resin may be cooled and solidified at the gate before entering the cavity, and may not be filled. Therefore, if both of the above two conditions are not satisfied, it is difficult to obtain a simultaneously decorated decorative molded product with a decorative sheet made of a general-purpose material.

The test temperature T is 160 to 28
Preferably it is 0 ° C. When the test temperature T is lower than 160 ° C., the flow of the molten resin is deteriorated, and there is a possibility that a short-circuit may occur in the molded product or the decorative sheet may have poor adhesion. On the other hand, when the test temperature T exceeds 280 ° C., there is a possibility that resin burns may occur and the molded product may be colored, or carbonization may occur and 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. And
When the molten resin is injected into the mold through the nozzle,
It is thought that there is a temperature drop of about 40 ° C. Therefore, the nozzle indicated temperature of the injection molding machine may be regarded as indicating the temperature of the resin immediately before the injection, that is, the test temperature T.

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

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

The transfer material has 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, a base sheet of a usual transfer material such as a resin sheet of a polypropylene resin, a polyethylene resin, a polyamide resin, a polyester resin, an acrylic resin, a polyvinyl chloride resin or the like is used. 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. Further, it is also possible to form an adhesive layer by bonding sheets having adhesiveness made of the above materials by a laminating method or the like.

The structure 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 using the above-described transfer material and the simultaneous 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, a molten resin is injected and filled into the die from a gate provided in the fixed die, and a transfer material is adhered to the surface of the transfer material simultaneously with the formation of the transfer object.

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 that when the transfer material is used 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 1) A polyethylene terephthalate film having a thickness of 0.08 mm was used as a base sheet, and a transparent window was formed in the center of the base sheet using a strong adhesive ink. A pattern layer is formed by a gravure printing method in eight colors so as to have a pattern consisting of a pattern and a character, and an adhesive for bonding to an ABS resin is further printed as an adhesive layer to obtain an insert film having a thickness of 0.1 mm. Decorative sheet.

The decorative sheet was inserted into a mold of a sleep rate system for producing a nameplate, and insert molding was performed. As the gate, a gate having a circular pinpoint gate with a diameter of 0.8 mm on the back surface of the panel was used (a
= 0.8).

In the injection molding step, ABS resin melted at 240 ° C. in the cylinder was injected into the mold through the gate to obtain a simultaneously decorated decorative molded product. The melt flow rate b of the ABS resin used here was a test temperature of 220 ° C. and a piston pressing force of 100 in the test method of ASTM D1238.
25 g / 10 min under N (T = 220, P =
100, b = 25).

In this case, b / (T × P) ≒ 1.1 × 10
⁻³ and a × b = 20. In the simultaneously molded decorative molded product thus obtained, the decorative sheet did not wrinkle, and the adhesive layer and the design layer 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 1 except that an ABS resin to which glass fiber was added was used. The melt flow rate b of the ABS resin containing glass fiber was 0.3 g / 10 min at a test temperature of 220 ° C. and a piston pressing force of 100 N according to the test method of ASTM D1238 (T = 220, P = 10
0, b = 0.3).

In this case, b / (T × P) ≒ 1.4 × 10
⁻⁵ and a × b = 0.24. In the thus obtained simultaneously decorated decorative molded product, the resin was not sufficiently filled, and the resin could be filled into the product shape by increasing the injection pressure. The adhesive layer and the design layer of the sheet were damaged, and the design collapsed.

(Embodiment 2) Next, the gate diameter a is set to 0.84 m.
m was obtained in the same manner as in Comparative Example except that the product was enlarged to m (a = 0.84).

In this case, b / (T × P) ≒ 1.4 × 10
⁻⁵ and a × b ≒ 0.25. The thus obtained simultaneously decorated decorative molded product was free from wrinkling of the decorative sheet, and the adhesive layer and the design layer were not damaged and the design did not collapse.

[0059]

Since the present invention has the above-described structure, it has the following effects.

According to the method of manufacturing a simultaneously decorated decorative molded product of the present invention, a decorative sheet is placed in a mold having a cavity,
Injection of a molten resin into a mold to obtain a molded article in which a decorative sheet and a resin are integrated, a method for manufacturing a simultaneously-decorated molded article, wherein the gate diameter of the mold is a (mm) and ASTM D12
The melt flow rate at the test temperature T (° C.) and the pressing force P (N) of the piston in the test method specified in 38 is b (g).
/ 10 min), 1 × 10 ⁻⁵ ≦ b / (T ×
P) and the relationship of 0.25 ≦ a × b are both satisfied, so that the resin is sufficiently filled in the cavity and the decorative simultaneous sheet has an excellent appearance without wrinkling or damage. Can be easily obtained.

Claims (4)

(57) [Claims] A decorative sheet is provided in a mold having a cavity, and a molten resin is injected into the mold to obtain a molded article in which the decorative sheet and the resin are integrated. In the manufacturing method, the gate diameter of the mold is set to a (mm),
Test temperature T in the test method specified in MD1238
(° C.), when the melt flow rate at the pressing force P (N) of the piston is b (g / 10 min), 1 × 10
^A method for producing a simultaneously decorated decorative molded product, wherein the relationships of ⁻⁵ ≦ b / (T × P) and 0.25 ≦ a × b are both satisfied. 2. The method according to claim 1, wherein the gate is a pin point gate having a gate diameter of 0.5 to 5 mm. 3. The method for producing a simultaneously decorated decorative molded product according to claim 1, wherein the test temperature T is 160 to 280 ° C. 4. The method for producing a simultaneously decorated decorative molded product according to claim 1, wherein the decorative sheet is a transfer material or an insert material.