JP2012176593A - Method for manufacturing resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a resin molding with a coat layer by which a coat layer excellent in durability can be formed without lengthening a molding cycle.SOLUTION: A coating agent (120) of a heat curing type is applied to a cavity surface of a core plate (110a) of a metal mold for injection molding. At this time, a temperature Tm of the core plate (110a) is made lower than a thermal curing temperature Tc of the coating agent (120). Thereafter, a thermoplastic resin (130) is injected into a cavity of the metal mold for injection molding. At this time, a maximum temperature Tp of the cavity surface of the core plate (110a) becomes equal to or higher than the thermal curing temperature Tc of the coating agent (120). Thereby, the coating agent (120) is cured by the heat of the thermoplastic resin (130).

Description

  The present invention relates to a method for producing a resin molded product having a coating layer on the surface.

  In recent years, detection devices such as microwell plates and microchannel chips have been used in the medical field and scientific field to detect biological substances such as proteins and nucleic acids.

  Conventionally, a glass substrate processed has been used as these detection devices. However, since glass substrates are expensive, recently, detection devices made of resin that are inexpensive and easy to mass-produce have become mainstream.

  However, in the detection device made of resin, there is a possibility that the detection sensitivity may be lowered when proteins, fluorescent dyes, and the like adhere to the surface of the resin substrate. Therefore, in order to prevent protein and the like from adhering to the resin substrate surface and improve the flow of the solution, it is widely performed to make the resin substrate surface hydrophilic.

  As a means for improving the hydrophilicity of the resin molded product, it is conceivable to increase the surface free energy of the resin molded product. For example, a method of forming a coat layer (hydrophilization layer) containing a photocatalyst such as titanium oxide on the surface of a resin molded product has been proposed (see, for example, Patent Document 1). Patent Document 1 discloses forming a hydrophilic layer containing a photocatalyst by applying a coating agent (hydrophilizing agent) containing a photocatalyst or a precursor thereof to the surface of a bathtub made of a resin or the like. .

  However, the resin molded product (tub) manufactured by the method described in Patent Document 1 has a problem of durability. That is, in the resin molded product manufactured by the method described in Patent Document 1, since the adhesion between the resin base material and the hydrophilic layer is poor, the hydrophilic layer may be peeled off with use.

  As a means for solving this problem of durability, a method of previously forming a coat layer (hydrophilic layer) on the cavity surface of a molding die has been proposed (for example, see Patent Document 2). In Patent Document 2, 1) a coating agent (hydrophilizing agent) is applied to the cavity surface of a molding die to which a release agent is applied, and 2) the applied hydrophilic agent is dried by heating to form a hydrophilic layer. 3) Injecting a thermosetting resin into the cavity of the molding die to form a resin molded product, and transferring the hydrophilic layer to the surface of the resin molded product. 4) To the surface of the demolded resin molded product. There is described a method for producing a resin molded product, in which an attached hydrophobic substance (such as a release agent) is removed by polishing.

  By adopting the production method described in Patent Document 2, it is possible to produce a resin molded article having good adhesion between the resin base material and the hydrophilic layer and excellent durability.

JP-A-10-225393 JP 2001-121603 A

  However, the manufacturing method described in Patent Document 2 has a problem that the molding cycle becomes long and the manufacturing efficiency decreases.

  In the method of Patent Document 2, before injecting the thermosetting resin into the cavity of the molding die, the coating agent (hydrophilic agent) applied to the cavity surface is dried by heating for a certain time (for example, 10 minutes). (Hydrophilic layer) must be formed.

  In the method of Patent Document 2, since thermosetting resin is mainly used, the thermosetting resin in the cavity must be heated for a long time (for example, 30 minutes).

  Further, in the method of Patent Document 2, since a hydrophobic release agent is applied to the cavity surface of the molding die, the mold release agent attached to the surface of the resin molded product must be removed after demolding. Don't be.

  As described above, in the manufacturing method described in Patent Document 2, it takes time to form the coat layer, cure the thermosetting resin, remove the release agent, and the like, resulting in a long molding cycle.

  This invention is made | formed in view of this point, and provides the manufacturing method of the resin molded product which has a coating layer which can form the coating layer excellent in durability, without lengthening a shaping | molding cycle. For the purpose.

  The present inventor has found that the above problem can be solved by applying a thermosetting coating agent to the cavity surface of the molding die and curing the coating agent with the heat of the thermoplastic resin injected into the cavity. Further studies were made to complete the present invention.

That is, the present invention is a method for producing a resin molded product having a coating layer on a surface thereof: a first step of applying a thermosetting coating agent to at least a part of a cavity surface of an injection mold; A thermoplastic resin is injected into the cavity of the injection mold to which the coating agent has been applied to cure the coating agent applied to the cavity surface and to form a molded article of the thermoplastic resin. The temperature of the injection mold in the first step is T _m , the thermosetting temperature of the thermosetting coating agent is T _c , and the cavity surface in the second step This is a method for producing a resin molded product, wherein “T _m <T _c ≦ T _p ”, where T _p is the maximum temperature of the resin.

  According to the present invention, it is possible to produce a resin molded product having a coating layer with excellent durability without lengthening the molding cycle.

The schematic diagram for demonstrating one Embodiment of the manufacturing method of this invention The schematic diagram which shows the example of the resin molded product manufactured with the manufacturing method shown by FIG.

  The production method of the present invention is a method for producing a resin molded product having a coating layer on the surface by an injection molding method. Here, the “coat layer” means a layer (function-imparting layer) that imparts some function to the surface of the resin molded product. The coat layer is, for example, a hydrophilic layer, a water repellent layer, an antistatic layer, or the like, but is not limited thereto.

  The manufacturing method of the present invention includes 1) a first step of applying a thermosetting coating agent to the cavity surface of the injection mold, and 2) applying heat to the cavity of the injection mold coated with the coating agent. And a second step of injecting a plastic resin to form a resin molded product. Hereinafter, each step will be described.

1) First Step In the first step, a thermosetting coating agent is applied to the cavity surface of the injection mold. Here, the “cavity surface” refers to a surface that forms a cavity (cavity portion) of an injection mold.

  The shape, size, material and the like of the injection mold to be used are not particularly limited, and can be appropriately selected according to the resin molded product to be manufactured.

  The coating agent is applied to at least a part of the cavity surface of the injection mold. That is, the coating agent may be applied to the entire surface of the cavity, or may be applied to only a part of the surface. Different types of coating agents may be applied to different areas of the cavity surface.

  The type of the coating agent is not particularly limited as long as it is a thermosetting type, and can be appropriately selected from known coating agents. Examples of the coating agent include a thermosetting hydrophilic agent, a water repellent agent, an antistatic agent, and the like. The coating agent can be prepared by dispersing or dissolving a known function-imparting substance or binder in a solvent. A commercially available coating agent may be used.

  When applying the coating agent to the cavity surface, it is preferable that the cavity surface is not subjected to mold release treatment. This is because if the release agent is applied to the cavity surface, it is necessary to remove the release agent attached to the surface of the resin molded product after releasing the resin molded product. For example, by using a silica-based or fluorine-based coating agent as a coating agent to be applied to the cavity surface, the resin molded product can be easily released without applying a release agent.

  The method for applying the coating agent is not particularly limited, and can be appropriately selected according to the shape of the injection mold, the application area, and the like. Examples of the method for applying the coating agent include a spray method and a roll coating method.

As will be described later, the manufacturing method of the present invention is characterized in that in the second step, the coating agent is cured by the heat of the injected thermoplastic resin. That is, the coating agent is not cured until the thermoplastic resin is injected into the cavity in the second step. Accordingly, in a first step of applying the coating agent to the cavity surface, so that the coating agent is not cured, it is preferable to lower than the thermal curing temperature T _c of the coating agent temperature T _m of a injection mold ( T _m <T _c ). The temperature of the injection mold can be adjusted with a mold temperature controller or the like.

2) Second Step In the second step, a thermoplastic resin is injected into the cavity of the injection mold to which the coating agent has been applied to form a resin molded product.

  One feature of the production method of the present invention is that a thermoplastic resin is used instead of a thermosetting resin. In the production method of the present invention, the coating agent is not cured at the time when the resin is injected. Therefore, when a low-temperature thermosetting resin is injected into the cavity, the coating agent and the thermosetting resin are mixed and a coating layer cannot be formed. On the other hand, when a thermoplastic resin is used, a thermoplastic resin having a certain high temperature is injected into the cavity, so that the coating agent is cured by the heat of the thermoplastic resin without mixing the coating agent and the thermoplastic resin. A layer can be formed.

  The type of the thermoplastic resin is not particularly limited, and can be appropriately selected from known thermoplastic resins according to required properties (for example, transparency and chemical resistance). Examples of the thermoplastic resin that can be used include polyethylene terephthalate, polycarbonate, acrylic resin (polymethyl methacrylate, etc.), polyvinyl chloride, polyethylene, polypropylene, polyether sulfone, and the like.

As described above, the manufacturing method of the present invention is characterized in that, in the second step, the coating agent is cured by the heat of the injected thermoplastic resin. Therefore, the temperature of the thermoplastic resin to be injected is adjusted so that the maximum temperature T _p of the cavity surface when the thermoplastic resin is injected is equal to or higher than the thermosetting temperature T _c of the coating agent (T _c ≦ T _p ). Is preferred. The temperature of the thermoplastic resin can be adjusted by adjusting the temperature of the cylinder of the injection device.

Before the thermoplastic resin is injected into the cavity, the thermoplastic resin is heated so as to have a fluidity sufficient to fill the cavity. When a high-temperature thermoplastic resin is injected into the cavity and touches the cavity surface, a skin layer of the resin molded product starts to be formed, and the temperature of the cavity surface rapidly increases. The aforementioned “maximum temperature T _p of the cavity surface when the thermoplastic resin is injected” means the maximum temperature in the temperature change of the cavity surface at this time.

  When the thermoplastic resin is injected into the cavity of the injection mold, the coating agent applied to the cavity surface is cured by the heat of the thermoplastic resin to form a coat layer. Curing of the coating agent receives heat by touching the thermoplastic resin and proceeds almost simultaneously with the formation of the skin layer of the thermoplastic resin. As a result, the coat layer adheres to the surface of the formed resin molded product.

  After the coating agent is sufficiently cured and the resin molded product is sufficiently solidified, the resin molded product having the coat layer is released. Usually, the coating agent is sufficiently cured between the time when the resin molded product is cooled and removed from the mold. Therefore, there is no need to separately set the heating time for curing the coating agent.

  By the above procedure, a resin molded product having a coat layer on the surface can be produced.

  In the production method of the present invention, since the coating agent is cured by the heat of the thermoplastic resin injected into the cavity, it is not necessary to heat and dry the coating agent before injecting the thermoplastic resin. Further, since the manufacturing method of the present invention uses a thermoplastic resin, it is not necessary to heat the resin in the cavity for a predetermined time. Furthermore, the manufacturing method of the present invention does not require the release agent to be applied to the cavity surface, and therefore it is not necessary to remove the release agent attached to the surface of the resin molded product.

  Thus, the production method of the present invention can produce a resin molded product having a coating layer with excellent durability without lengthening the molding cycle.

(Embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram for explaining a manufacturing method according to an embodiment of the present invention. Here, an example of manufacturing the microwell plate shown in FIG. 2 is shown.

  First, as shown in FIG. 1A, an injection mold core plate 110a and cavity plate 110b are prepared. It is not necessary to apply a release agent to the core plate 110a and the cavity plate 110b.

Next, as shown in FIG. 1B, a thermosetting coating agent 120 (for example, a silica-based hydrophilizing agent) is applied to the surface of the core (convex portion) of the core plate 110a. At this time, the temperature _{T m} of a core plate 110a, to lower than the thermal curing temperature _{T c} of the coating agent 120. Temperature T _m of a core plate 110a is various conditions such as the filling property and the molding cycle of thermoplastic resin in the subsequent steps is also set in consideration. For example, when the thermosetting temperature T _c of the coating agent 120 is 120 ° C., the temperature T _m of the core plate 110a is set to 100 ° C. Therefore, the applied coating agent 120 is not cured.

Next, as shown in FIG. 1C, the core plate 110a and the cavity plate 110b are combined to perform mold clamping. In this case, the temperature _{T m} of a core plate 110a, to lower than the thermal curing temperature _{T c} of the coating agent 120.

Next, as shown in FIG. 1D, a thermoplastic resin 130 is filled into the cavity of the injection mold. At this time, the temperature of the thermoplastic resin 130 to be filled is adjusted so that the maximum temperature T _p of the cavity surface is _{equal to} or higher than the thermosetting temperature T _c of the coating agent 120. For example, when the thermosetting temperature _Tc of the coating agent 120 is 120 ° C., the temperature of the thermoplastic resin 130 to be filled is set to 320 ° C. so that the maximum temperature T _p of the cavity surface is 120 to 150 ° C. Thereby, the coating agent 120 applied to the core of the core plate 110a is cured, and the coat layer 140 is formed.

  Finally, as shown in FIGS. 1E and 1F, the core plate 110a and the cavity plate 110b are opened, and the resin molded product (microwell plate) 100 is released.

  The resin molded product (microwell plate) 100 shown in FIG. 2 can be manufactured by the above procedure. FIG. 2A is a plan view of the microwell plate 100. 2B is a cross-sectional view taken along line BB in FIG. 2A. As shown in these drawings, the coat layer 140 is firmly attached to the inner surface of the recess (well) of the microwell plate 100.

  In addition, when forming a coat layer in the recessed part of a resin molded product, the method of apply | coating a coating agent by the spray method etc. after forming a resin molded product is also considered. However, the coating agent can be applied more evenly when the coating agent is applied to the convex portion (core) of the core plate than to apply the coating agent to the concave portion of the resin molded product. Thus, when forming a coating layer in the recessed part of a resin molded product, the manufacturing method of this invention is especially suitable.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example, this invention is not limited by these Examples.

  In this example, a microwell plate (well diameter: 7.3 mm, well depth: 11 mm, plate thickness: 1.2 mm; see FIG. 2) in which a hydrophilic layer is formed on the inner surface of the well is prepared. Show.

  First, a silica-based (glass-based) hydrophilizing agent (Fressera R-EP4; Panasonic Electric Works Co., Ltd.) was applied to the surface of the core of the core plate using a spray gun while the injection mold was open. (See FIG. 1B). At this time, the temperature of the core plate and the cavity plate was adjusted to 100 ° C. using a mold temperature controller. In addition, the recommended curing conditions of the used hydrophilic treatment agent are 120 ° C. × 1 minute + normal temperature × 24 hours or 120 ° C. × 10 to 20 minutes.

  The application of the hydrophilizing agent by the spray gun was performed by an automatic spray machine attached to the molding machine, and it was set so that the surface of the core could be sprayed in accordance with the molding cycle. Use ME-5000SP (Musashi Engineering Co., Ltd.) for the spray controller of the automatic spray machine, ST-6SK (Fuso Seiki Co., Ltd.) for the spray valve, and SOT-1L (Musashi Engineering Co., Ltd.) for the straight one-touch tank. did. None of the core plate and cavity plate of the injection mold was subjected to release treatment.

  Next, the core plate and the cavity plate are combined and clamped (see FIG. 1C), and then molten polycarbonate (Iupilon H-3000R; Mitsubishi Gas Chemical Co., Ltd.) is injected into the cavity of the injection mold. did. At this time, the temperature of the injection mold was 100 ° C., and the temperature of the injection cylinder was 320 ° C. The maximum temperature of the cavity surface during injection was 120-150 ° C.

  50-60 seconds after injecting the polycarbonate, the core plate and the cavity plate were opened, and the resin molded product (microwell plate) was released (see FIG. 1F). As described above, the mold for injection molding was not subjected to release treatment, but could be easily released.

  By the above procedure, a microwell plate having a hydrophilic layer on the inner surface of the well could be produced in a short molding cycle (a few minutes level) (see FIG. 2). When the contact angle of the free surface of water on the inner surface of the well was evaluated using a solution in which blue ink was added to pure water, the contact angle of the well according to the manufacturing method of the present invention was higher than that of the well in which the hydrophilic layer was not formed. Smaller and better results were obtained.

  The production method of the present invention is useful, for example, as a method for producing a detection device such as a microwell plate or a microchannel chip used in the medical field or scientific field.

DESCRIPTION OF SYMBOLS 100 Resin molded product 110a Core plate 110b Cavity plate 120 Coating agent 130 Thermoplastic resin 140 Coating layer

Claims (4)

A method for producing a resin molded product having a coat layer on the surface,
Applying a thermosetting coating agent to at least a part of the cavity surface of the injection mold;
A thermoplastic resin is injected into the cavity of the injection mold to which the coating agent has been applied, and the coating agent applied to the cavity surface is cured, and a molded article of the thermoplastic resin is formed. Two steps,
The temperature of the injection mold in the first step is T _m , the thermosetting temperature of the thermosetting coating agent is T _c , and the maximum temperature of the cavity surface in the second step is T _p . Sometimes “T _m <T _c ≦ T _p ”,
Manufacturing method of resin molded product.   The method for producing a resin molded product according to claim 1, wherein the thermosetting coating agent is a hydrophilizing agent, a water repellent agent, or an antistatic agent.   The method for producing a resin molded product according to claim 1, wherein the thermosetting coating agent is a silica-based or fluorine-based coating agent.   The manufacturing method of the resin molded product of Claim 3 which does not apply | release a mold release agent to the cavity surface of the said metal mold | die for injection molding.

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