JP2010269541A - Rubber mold for electromagnetic wave irradiation molding and electromagnetic wave irradiation molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber mold for electromagnetic wave irradiation molding and an electromagnetic wave irradiation molding method for positively heating a thermoplastic resin composition near the inner wall face of a cavity, and effectively improving quality in appearance, shape, surface accuracy and the like and mechanical strength when molding the thermoplastic resin using the rubber mold. <P>SOLUTION: The rubber mold 2 for the electromagnetic wave irradiation molding comprises a rubber material, and is used for heating and molding a thermoplastic resin molding composition 6A to be filled in the cavity 22 by irradiating the thermoplastic resin molding 6A with the electromagnetic wave including a wave region of 0.78-2 μm. The rubber mold 2 has a surface layer 25 having infrared absorbing performance on an inner wall face 221 of the cavity 22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rubber mold and an electromagnetic wave irradiation molding method used for thermoforming a thermoplastic resin which is irradiated with electromagnetic waves and filled in a cavity.

In general, there are various molding methods such as injection molding, blow molding, extrusion molding, and press molding as methods for obtaining a resin molded product having a predetermined shape using a thermoplastic resin.
On the other hand, in Patent Document 1, when a resin molded product made of a thermoplastic resin is molded by a vacuum casting method using a rubber mold, the thermoplastic resin is selectively used with respect to the mold. A resin molding method that can be heated is disclosed. In this resin molding method, when the molten thermoplastic resin is filled in the cavity of the mold, the thermoplastic resin is irradiated with an electromagnetic wave including a wavelength region of 0.78 to 2 μm through the mold, Due to the difference in physical properties between the rubber constituting the mold and the thermoplastic resin, the thermoplastic resin can be positively heated as compared with the rubber mold.

JP 2007-216447 A

However, when the molten thermoplastic resin is filled into the rubber mold, the molten thermoplastic resin may be cooled in the vicinity of the inner wall surface of the cavity of the rubber mold, and the viscosity may increase. In this case, the fluidity of the thermoplastic resin is lowered, and it may be difficult to obtain a resin molded product with good surface accuracy. On the other hand, when the irradiation intensity of electromagnetic waves is increased, there is a problem that the deterioration of the rubber mold is accelerated, the number of possible uses is reduced, or the surface accuracy of the resin molded product to be molded is lowered. . Similarly, when the electromagnetic wave irradiation time is lengthened, deterioration of the resin molded product to be molded may be promoted.
In addition, the problem of lowering the fluidity of the thermoplastic resin is particularly prominent when the molded resin product to be molded has a shape such as a large size or a thin wall, or when the viscosity of the thermoplastic resin itself used for molding is high. Tend to be.

  The present invention has been made in view of such conventional problems. When a thermoplastic resin is molded using a rubber mold, the thermoplastic resin composition in the vicinity of the inner wall surface of the cavity is positively heated. It is intended to provide a rubber mold for electromagnetic wave irradiation molding and an electromagnetic wave irradiation molding method that can effectively improve the quality and mechanical strength of the appearance, shape, surface accuracy, etc. of the resin molded product to be molded. is there.

A first invention is a rubber mold that is made of a rubber material and is used for heat-molding a thermoplastic resin composition that fills a cavity by irradiating an electromagnetic wave including a wavelength region of 0.78 to 2 μm.
The rubber mold is a rubber mold for electromagnetic wave irradiation molding characterized by having a surface layer having infrared absorption performance on the inner wall surface of the cavity (Claim 1).

A second invention is a method of molding a resin molded article using the rubber mold for electromagnetic wave irradiation molding,
An arrangement step of arranging a particulate thermoplastic resin composition in the cavity;
A heating step of irradiating the thermoplastic resin composition in the cavity through the rubber mold with an electromagnetic wave including a wavelength region of 0.78 to 2 μm, and heating and melting the thermoplastic resin composition;
A filling step of filling a molten thermoplastic resin composition into an unfilled cavity portion left in the cavity;
A cooling step of cooling the thermoplastic resin composition in the cavity to obtain a resin molded product (claim 3).

A third invention is a resin molded product obtained by the electromagnetic wave irradiation molding method (claim 4).

  In the first invention, an electromagnetic wave including a wavelength region of 0.78 to 2 μm is irradiated to the thermoplastic resin composition in the cavity through the rubber mold. At this time, the thermoplastic resin composition can be selectively heated compared to the rubber mold due to the difference in physical properties between the rubber material constituting the rubber mold and the thermoplastic resin constituting the thermoplastic resin composition ( The heating amount of the thermoplastic resin composition can be increased). Thereby, the temperature rise of the rubber mold can be suppressed and the thermoplastic resin composition can be melted.

  The rubber mold according to the present invention has a surface layer having infrared absorption performance on the inner wall surface of the cavity, so that the surface layer actively absorbs electromagnetic waves including a wavelength region of 0.78 to 2 μm. be able to. Thereby, the thermoplastic resin composition in the vicinity of the inner wall surface of the cavity can be positively heated, the increase in the viscosity of the thermoplastic resin composition in the vicinity of the inner wall surface can be prevented, and the decrease in fluidity thereof can be suppressed. it can. Therefore, it is possible to effectively improve the quality, such as the appearance, shape, surface accuracy, and mechanical strength of the resin molded product molded by the rubber mold.

In the second invention, first, as an arranging step, a particulate thermoplastic resin composition is arranged in a rubber mold cavity. At this time, the thermoplastic resin composition can be filled into almost the entire cavity, or can be filled into a part of the cavity.
Next, as a heating step, an electromagnetic wave including a wavelength region of 0.78 to 2 μm is irradiated to the thermoplastic resin composition in the cavity through a rubber mold. At this time, similarly to the first invention, an electromagnetic wave including a wavelength region of 0.78 to 2 μm can be actively absorbed by the rubber-type surface layer. Thereby, the thermoplastic resin composition in the vicinity of the inner wall surface of the cavity can be positively heated, the increase in the viscosity of the thermoplastic resin composition in the vicinity of the inner wall surface can be prevented, and the decrease in fluidity thereof can be suppressed. it can.

  Next, as a filling step, the molten thermoplastic resin composition is filled into unfilled hollow portions left in the cavities due to melting of the particulate thermoplastic resin composition. At this time, the part where the particulate thermoplastic resin composition was present in the rubber mold cavity before the heating step, the part located in the lower vertical direction in the rubber mold cavity, or the rubber mold cavity The surface or the like is filled with a particulate thermoplastic resin composition. And the filling amount of the thermoplastic resin composition of the molten state newly filled in a cavity can be decreased.

Thereby, it is possible to fill the entire cavity with the thermoplastic resin composition without excessively increasing the filling pressure, and to effectively suppress deformation and opening of the rubber mold. Therefore, it is possible to prevent resin leakage from the split surface (parting surface) in the rubber mold, and when the resin molded product is obtained by the cooling process, the quality, machine, etc. of the resin molded product are obtained. Effective strength can be improved effectively.
In addition, the same thermoplastic resin composition can be used for the thermoplastic resin composition in the particle state used in the arranging step and the molten thermoplastic resin composition used in the filling step, and different thermoplastic resin compositions. Can also be used. When using different thermoplastic resin compositions, it is preferable to use a highly compatible thermoplastic resin in order to increase the mechanical strength.

  The resin molded product of the third invention is obtained by the electromagnetic wave irradiation molding method, and can effectively improve the quality such as appearance, shape, surface accuracy, and mechanical strength.

Explanatory drawing which shows the state which performed the arrangement | positioning process in the electromagnetic wave irradiation shaping | molding method in an Example. Explanatory drawing which shows the state which performs the vacuum process and heating process in the electromagnetic wave irradiation shaping | molding method in an Example. Explanatory drawing which shows the state which performed the filling process in the electromagnetic wave irradiation shaping | molding method in an Example. In an Example, the wavelength (nm) is taken on a horizontal axis and the light transmittance (%) is taken on the vertical axis | shaft, and the graph which shows the light transmittance about transparent silicone rubber and translucent silicone rubber. In an Example, explanatory drawing which shows the state filled with the small resin particle and the large resin particle in the cavity of a rubber mold. In an Example, explanatory drawing which shows the state which fills only the large resin particle in the cavity of a rubber mold.

Preferred embodiments of the rubber mold for electromagnetic wave irradiation molding and the electromagnetic wave irradiation molding method of the present invention described above will be described.
In the present invention, the reason why the thermoplastic resin can be selectively heated by the electromagnetic wave including the wavelength region of 0.78 to 2 μm as compared with the rubber mold is considered as follows.
That is, an electromagnetic wave including a wavelength region of 0.78 to 2 μm irradiated on the surface of the rubber mold has a higher ratio of being transmitted through the rubber mold and absorbed by the thermoplastic resin than a ratio absorbed by the rubber mold. I think. For this reason, it is considered that the energy of light by electromagnetic waves including a wavelength region of 0.78 to 2 μm is preferentially absorbed by the thermoplastic resin, and the thermoplastic resin can be selectively heated.

Moreover, as an electromagnetic wave irradiated to the said thermoplastic resin composition through the said rubber type | mold, not only the electromagnetic wave of the area | region whose wavelength is 0.78-2 micrometers, but the electromagnetic wave of an area | region other than this may also be contained. In this case, it is preferable that the electromagnetic wave irradiated to the thermoplastic resin through the rubber mold includes a larger amount of electromagnetic waves in a region having a wavelength of 0.78 to 2 μm than electromagnetic waves in other regions.
The reason why electromagnetic waves in the wavelength region of 0.78 to 2 μm are used for heating the thermoplastic resin is that the electromagnetic waves in this wavelength region are easily transmitted through the rubber mold, and are absorbed by the thermoplastic resin. This is because it has the property of being easily processed.

The electromagnetic wave preferably has an intensity peak in a wavelength region of 0.78 to 2 μm. In this case, a halogen heater, an infrared lamp, or the like having a predetermined distribution characteristic for the wavelength of the emitted electromagnetic wave can be used as the electromagnetic wave generation source.
The rubber mold can be formed from a transparent or translucent silicone rubber as a rubber material. The hardness of this silicone rubber can be set to 25-80 in the JIS-A standard measurement.

The thermoplastic resin composition (resin particles) in the above particle state is obtained by mechanical pulverization (normal temperature, freeze pulverization, wet pulverization, jet pulverization), spraying (drying, coagulation), forced emulsification (melting emulsification, solution emulsification). It can be produced by various methods such as suspension polymerization and emulsion polymerization.
For example, as the resin particles, those produced by freeze-grinding thermoplastic resin pellets obtained by an extruder can be used. According to freeze pulverization, resin particles having various particle sizes can be produced. Further, as the resin particles, those produced by a so-called underwater cutting method by attaching a small-diameter die to the tip of the extruder can also be used. According to this extruded water cut method, resin particles of about 0.5 mm can be produced easily and inexpensively.
The resin particles can also be obtained by classification, sieving, etc., if necessary.

As a thermoplastic resin used for the said thermoplastic resin composition, what absorbs the electromagnetic wave of a 0.78-2 micrometer wavelength range, and a heating is accelerated | stimulated can be used.
The thermoplastic resin used in the thermoplastic resin composition is not particularly limited as long as it includes a polymer having thermoplasticity, and is composed of ABS resin (acrylonitrile / butadiene / styrene resin), ASA resin (acrylate / styrene / acrylonitrile resin). ), AES resin (acrylonitrile / ethylene-propylene-diene / styrene resin), etc., rubber-reinforced styrene resin, polystyrene, styrene / acrylonitrile copolymer, styrene / maleic anhydride copolymer, (meth) acrylic acid ester / styrene Styrene resins such as copolymers, olefin resins such as polyethylene and polypropylene, acrylic resins, polycarbonate resins, polyester resins, polyamide resins, vinyl chloride resins, polyarylate resins, polyacetal resins, polyphenylenes Ether resin, polyphenylene sulfide resin, fluorine resin, imide resin, ketone resin, sulfone resin, urethane resin, polyvinyl acetate, polyethylene oxide, polyvinyl alcohol, polyvinyl ether, polyvinyl butyral, phenoxy resin, photosensitive resin, liquid crystal Examples thereof include polymers and biodegradable plastics. These can be used alone or in combination of two or more.

  Among the above thermoplastic resins, rubber-reinforced styrene resin, olefin resin, acrylic resin, polyester resin, polyamide resin, polyester resin and polycarbonate resin alloy, rubber reinforcement are suitable for molding of molded products. Examples include alloys of styrene resins and polycarbonate resins, rubber-reinforced styrene resins, and alloys of polyester resins.

In the first invention, the surface layer is obtained by applying a liquid containing an infrared absorber, and the application amount of the infrared absorber is preferably 0.01 to 100 g / m ² ( Claim 2).
In this case, the application amount of the infrared absorber is appropriate, and the effect of positively heating the thermoplastic resin composition in the vicinity of the inner wall surface of the cavity can be easily obtained.
The surface layer can be formed by applying a liquid containing an infrared absorber and then drying. The surface layer can be maintained in a formation state over a plurality of times using a rubber mold, and is formed again on the inner wall surface of the cavity after molding the resin molded product once or a plurality of times. You can also.

The liquid containing the infrared absorbent can be applied by applying a solution in which the infrared absorbent is dissolved, a suspension in which the infrared absorbent is dispersed, an emulsion in which the infrared absorbent is emulsified, or the like. Moreover, the liquid containing an infrared absorber can be made into various paints having infrared absorption performance.
The surface layer can also be formed by sticking a resin film containing an infrared absorber to the inner wall surface of the cavity.

Further, as the infrared absorber, various agents that absorb electromagnetic waves including a near infrared wavelength region of 0.78 to 2 μm can be used.
As the infrared absorbent, either an inorganic infrared absorbent or an organic infrared absorbent can be used. The inorganic infrared absorber is selected from the group consisting of metal particles, carbon black, metal oxides such as tin oxide, zinc oxide, copper oxide, antimony-doped tin oxide, indium-doped tin oxide, In, Ga, Al, and Sb. And metal complex compounds such as zinc oxide containing at least one element.
Organic infrared absorbers include anthraquinone dyes, cyanine dyes, polymethine dyes, azomethine dyes, azo dyes, polyazo dyes, diimonium dyes, aminium dyes, phthalocyanine dyes, naphthalocyanine dyes, India Examples include cyanine dyes, naphthoquinone dyes, indolephenol dyes, triallylmethane dyes, metal complex dyes, dithiol nickel complex dyes, azocobalt complex dyes, squarylium dyes, and the like.

Examples of the rubber mold for electromagnetic wave irradiation molding and the electromagnetic wave irradiation molding method of the present invention will be described below with reference to the drawings.
As shown in FIGS. 1 to 3, the rubber mold 2 for electromagnetic wave irradiation molding in this example is made of a rubber material, and radiates an electromagnetic wave including a wavelength region of 0.78 to 2 μm to fill the cavity 22. Used to heat mold the plastic resin composition 6A. The rubber mold 2 has a surface layer 25 having infrared absorption performance on the inner wall surface 221 of the cavity 22.

Hereinafter, the rubber mold 2 for electromagnetic wave irradiation molding and the electromagnetic wave irradiation molding method of this example will be described in detail with reference to FIGS.
In this example, as the thermoplastic resin compositions 6A and 6B, an ABS resin that is an amorphous resin and a rubber-reinforced styrene resin is used.
The rubber mold 2 of this example is made of a transparent or translucent silicone rubber. In the rubber mold 2, a master model (handmade product etc.) of a resin molded product 60 to be molded is placed in a liquid silicone rubber, the silicone rubber is cured, and the cured silicone rubber is cut open. It can produce by taking out a master model from.

  Further, as shown in FIG. 1, the rubber mold 2 of this example is formed by forming one dividing surface 20 and combining two dividing mold parts 21. On the other hand, when the shape of the resin molded product 60 to be molded is complicated, the rubber mold 2 can be formed by combining three or more divided mold portions 21. At the time of molding, the plurality of divided mold parts 21 are held in a combined state by means for preventing mold opening. Moreover, the division | segmentation surface 20 can be easily aligned with the division | segmentation type | mold parts 21 by forming in an irregular wave shape etc.

In the electromagnetic wave irradiation molding method of this example, a thermoplastic resin is injection molded into the rubber mold 2 using the molding apparatus 1. As shown in FIGS. 1 to 3, the molding apparatus 1 includes the following pressure vessel 3, vacuum pump 31, injection cylinder 52, injection cylinder 53, electromagnetic wave generation means 4, and filter 43.
The pressure vessel 3 is configured to accommodate the rubber mold 2, and is configured to form a vacuum state by a vacuum pump 31 connected to the pressure vessel 3. The injection cylinder 52 is configured to inject the particulate thermoplastic resin composition 6 </ b> A into the cavity 22 through the injection portion 23 formed in the rubber mold 2. The injection cylinder 53 is configured to inject the molten thermoplastic resin composition 6B at a predetermined pressure into the cavity 22 through the injection portion 23 formed in the rubber mold 2. In this example, the pressure of the molten thermoplastic resin composition 6B injected from the injection cylinder 53 into the rubber mold 2 is set to 0.5 to 5 MPa.

The electromagnetic wave generating means 4 includes an electromagnetic wave (light) generating source 41 and a reflector (reflecting plate) 42 for guiding the electromagnetic wave generated by the generating source 41 in the direction of the rubber mold 2. As the electromagnetic wave generating means 4 of this example, a near infrared halogen heater having a light intensity peak in the vicinity of about 1.2 μm in the near infrared region is used. This near infrared halogen heater is configured to emit an electromagnetic wave including a wavelength region of 0.78 to 4 μm. The filter 43 of this example is quartz glass that reduces the amount of transmission of electromagnetic waves having a wavelength exceeding 2 μm.
2 and 3, an electromagnetic wave emitted from the electromagnetic wave generating means 4 is indicated by an arrow X.

  In addition, the absorbance to electromagnetic waves (light) including a wavelength region of 0.78 to 2 μm (a measure indicating the absorption intensity with respect to light of a specific wavelength) is the rubber resin mold 2 made of ABS resin used as a thermoplastic resin. It is larger than the silicone rubber used. The absorbance can be measured using, for example, Shimadzu UV3100.

  FIG. 4 shows the light transmittance of each silicone rubber with the wavelength (nm) on the horizontal axis and the light transmittance (%) on the vertical axis for transparent silicone rubber and translucent silicone rubber. It is a graph. In the figure, it can be seen that each silicone rubber transmits light having a wavelength between 200 and 2200 (nm). Therefore, when near infrared rays (light having a wavelength region of 0.78 to 2 μm), which is the wavelength region, are irradiated on the surface of the rubber mold 2 made of silicone rubber, most of the near infrared rays are transmitted through the rubber die 2. It can be absorbed by a thermoplastic resin. It can be seen that the thermoplastic resin can be selectively heated as compared with the rubber mold 2.

The surface layer 25 on the inner wall surface 221 of the cavity 22 of the rubber mold 2 in this example is obtained by evaporating the solvent by applying and drying a paint containing an infrared absorber. The application amount of the infrared absorber in the surface layer 25 of this example is 0.01 to 100 g / m ² .
The surface layer 25 can also be formed by sticking a resin film containing an infrared absorbent to the inner wall surface 221 of the cavity 22. It is also conceivable to include an infrared absorber in the rubber mold 2 itself (a rubber material used when the rubber mold 2 is produced). However, according to this method, the temperature rise of the rubber mold 2 itself is promoted. Therefore, it is preferable to form a surface layer 25 containing an infrared absorber on the inner wall surface 221 of the cavity 22 of the rubber mold 2.

Next, a method for manufacturing the resin molded product 60 using the molding apparatus 1 will be described in detail.
In the electromagnetic wave irradiation molding method of this example, when the resin mold 60 is molded by filling the rubber mold 2 with a thermoplastic resin, the particulate thermoplastic resin composition 6A and the molten thermoplastic resin composition 6B are used. And are used. In this example, ABS resins having different compositions are used for the thermoplastic resin composition 6A and the thermoplastic resin composition 6B.
The particulate thermoplastic resin composition 6A contains 0.1 to 20% by mass of small resin particles 62 having a particle diameter of 1 to 100 μm, the remainder being larger than the small resin particles 62 and having a particle diameter of 200. Those composed of large resin particles 61 having a size of ˜3000 μm are used.

  In molding the resin molded product 60, first, as shown in FIG. 1, as an arrangement step, the particle size is 1 to 1 on the inner wall surface 221 of the cavity 22 in the split mold portion 21 with respect to the rubber mold 2 in an open state. 100 μm small resin particles 62 are sprinkled and arranged. Next, the injection cylinder 52 is set in the injection part 23 of the rubber mold 2 in a closed state, and large resin particles 61 having a particle diameter of 200 to 3000 μm are put into the cavity 22 of the rubber mold 2. At this time, the content ratio of the thermoplastic resin composition 6A charged into the cavity 22 is such that the large resin particles 61 are 80 to 99.9% by mass and the small resin particles 62 are 0.1 to 20% by mass. To. Then, the thermoplastic resin composition 6 </ b> A is disposed (filled) in almost the entire cavity 22.

  When the small resin particles 62 are sprinkled on the inner wall surface 221 of the cavity 22, most of the small resin particles 62 adhere to the inner wall surface 221 of the cavity 22. Here, the rubber mold 2 of the present example is formed of silicone rubber, and the small resin particles 62 are effectively applied to the inner wall surface 221 of the cavity 22 made of silicone rubber by having a particle diameter of 1 to 100 μm. Can be attached.

  Further, when the large resin particles 61 are put into the cavity 22, the small resin particles 62 are attached to the inner wall surface 221 of the cavity 22. Thereby, the large resin particles 61 can pass (drop) inside the small resin particles 62 in the cavity 22. Therefore, the filling of the thermoplastic resin composition 6A into the cavity 22 can be performed smoothly. The small resin particles 62 and the large resin particles 61 can be filled by adding vibration or air current, in addition to filling by the dead weight.

Next, as shown in FIG. 2, as a vacuum process, the vacuum vessel 31 is evacuated by the vacuum pump 31, and the space left in the cavity 22 of the rubber mold 2 is evacuated.
Next, as shown in the figure, as a heating process, the electromagnetic wave including the wavelength region of 0.78 to 4 μm emitted from the electromagnetic wave generating means 4 is transmitted through the filter 43, and the transmitted electromagnetic wave after being transmitted through the filter 43 is The thermoplastic resin composition 6A in the cavity 22 is irradiated through the rubber mold 2. At this time, the thermoplastic resin composition 6A is selectively heated compared to the rubber mold 2 due to the difference in physical properties between the rubber material constituting the rubber mold 2 and the thermoplastic resin constituting the thermoplastic resin composition 6A. (The heating amount of the thermoplastic resin composition 6A can be increased). Thereby, the temperature rise of the rubber mold 2 can be suppressed and the thermoplastic resin composition 6A can be melted. And in the cavity 22, when the thermoplastic resin composition 6A is melted, an unfilled cavity portion 220 for newly filling the thermoplastic resin composition 6B is formed.

  Further, when performing the vacuum process and the heating process, the rubber mold 2 is deformed so that the cavity 22 is reduced in the direction in which the split mold part 21 faces (the direction perpendicular to the split surface 20). And the state of the cavity 22 after performing a heating process will be various states with the conditions of shaping | molding. In particular, when the fluidity of the thermoplastic resin composition 6A is not so good, the molten thermoplastic resin composition 6A is unlikely to sink below the cavity 22, and a bubble in which a large number of bubbles are formed in the central portion of the cavity 22 An unfilled cavity portion 220 is formed as a wake-up state.

  And rubber mold 2 of this example has surface layer 25 which has infrared absorption performance in inner wall surface 221 of the cavity 22, so that electromagnetic waves including a wavelength region of 0.78-2 μm are applied to surface layer 25. Can be actively absorbed. Thereby, the thermoplastic resin composition 6A in the vicinity of the inner wall surface 221 of the cavity 22 can be positively heated, and an increase in the viscosity of the thermoplastic resin composition 6A in the vicinity of the inner wall surface 221 is prevented, and its fluidity is lowered. Can be suppressed. Therefore, the quality, mechanical strength, and the like of the appearance, shape, and surface accuracy of the resin molded product 60 molded by the rubber mold 2 can be effectively improved.

  Next, as shown in FIG. 3, as the filling step, the injection cylinder 53 is set in the injection portion 23 of the rubber mold 2, and the molten thermoplastic resin composition 6 </ b> B is added to the unfilled cavity portion 220 of the cavity 22 by 0.00. Fill with an injection pressure of 1-5 MPa. Further, in the filling step of this example, irradiation of the transmitted electromagnetic wave to the thermoplastic resin composition 6A and the thermoplastic resin composition 6B through the rubber mold 2 is continued, and the thermoplastic resin composition 6A in the cavity 22 and The thermoplastic resin composition 6B is heated.

When the thermoplastic resin composition 6B in the molten state is filled, the thermoplastic resin composition 6A melted from the particle state is placed on the portion located on the inner wall surface 221 (rubber surface) of the cavity 22 of the rubber mold 2. Filled. Therefore, the thermoplastic resin composition 6B can fill the unfilled cavity portion 220 in a state of being almost separated from the thermoplastic resin composition 6A. Thereby, the resin molded product 60 consisting of the thermoplastic resin composition 6A and the thermoplastic resin composition 6B can be molded by a very simple method.
And in the resin molded product 60 to shape | mold, an outer side layer can be formed with the thermoplastic resin composition 6A, and a center layer can be formed with the thermoplastic resin composition 6B. Due to the difference in physical properties between the thermoplastic resin composition 6A constituting the outer layer and the thermoplastic resin composition 6B constituting the center layer, various properties required for the resin molded product 60 can be satisfied.

  In addition, since the cavity 22 is filled with the thermoplastic resin composition 6A, the filling amount of the molten thermoplastic resin composition 6B to be newly filled can be reduced. Thereby, it is possible to fill the entire cavity 22 with the thermoplastic resin compositions 6A and 6B without significantly increasing the filling pressure (injection pressure), and to effectively suppress deformation and opening of the rubber mold 2. it can. Therefore, resin leakage from the dividing surface (parting surface) 20 in the rubber mold 2 can be prevented, and when the resin molded product 60 is obtained by performing the cooling process, the appearance, shape, and surface of the resin molded product 60 are obtained. The quality such as accuracy and the mechanical strength can be effectively improved.

  By the way, in the conventional rubber mold 2 that does not have the surface layer 25, it takes time to raise the temperature of the thermoplastic resin compositions 6A and 6B, and the resin molded product 60 and the rubber mold that are molded by increasing the irradiation intensity of electromagnetic waves. There was a problem such as thermal deterioration in 2. On the other hand, by forming the surface layer 25 containing an infrared absorber on the inner wall surface 221 of the cavity 22 in the rubber mold 2, these problems are improved, the molding time is shortened, the resin molded product 60, and the rubber mold 2 can be alleviated.

Therefore, according to the electromagnetic wave irradiation molding method of this example, when the thermoplastic resin is molded using the rubber mold 2, the thermoplastic resin composition 6A in the vicinity of the inner wall surface 221 of the cavity 22 is positively heated. The resin molded product 60 that can improve the quality such as shape and surface accuracy and satisfy various required characteristics can be molded by a simple method.
Further, the effect of effectively improving the quality, such as the appearance, shape, surface accuracy, and mechanical strength of the resin molded product 60 is used when the molded resin molded product 60 has a large or thin shape, or is used for molding. This is particularly remarkable when the viscosity of the thermoplastic resin is high.

  In addition, in the electromagnetic wave irradiation molding method of this example, the surface layer 25 containing the infrared absorber is formed on the inner wall surface 221 of the cavity 22 of the rubber mold 2 so that the thermoplastic resin composition 6A has an infrared absorber. Etc. are not contained. Therefore, it is prevented that the resin molded product 60 to be molded is slightly discolored due to the inclusion of this component.

(Effect simulation)
FIGS. 5 and 6 show an enlarged view of the state in which the thermoplastic resin particles 61 and 62 are filled in the cavity 22 of the rubber mold 2. FIG. 5 shows a case where the large resin particles 61 and the small resin particles 62 are filled in the cavity 22, and FIG. 6 shows a case where only the large resin particles 61 are filled in the cavity 22.
As shown in FIG. 6, when trying to fill only the large resin particles 61 into the cavity 22, the large resin particles 61 adhere to the inner wall surface 221 of the cavity 22, and the inside of the large resin particles 61 is further separated by another large particle. It is considered difficult for the shaped resin particles 61 to pass (drop) (indicated by an arrow T).

  On the other hand, as shown in FIG. 5, when the large resin particles 61 are filled after the small resin particles 62 are filled in the cavity 22, the small resin particles 62 are effectively applied to the inner wall surface 221 of the cavity 22. It is assumed that the large resin particles 61 adhere and pass (drop) (indicated by an arrow T) inside the small resin particles 62 with almost no adhesion to the inner wall surface 221 of the cavity 22. Thereby, according to the 1st thermoplastic resin composition 6A containing the large resin particle 61 and the small resin particle 62, it thinks that the substantially whole cavity 22 can be filled effectively.

(Evaluation test)
In this evaluation test, a thermoplastic resin was used for the rubber mold 2 (invention product) in which the surface layer 25 containing the infrared absorber was formed and the rubber mold 2 (comparative product) in which this surface layer 25 was not formed. The time required for the ABS resin as the composition 6A to melt (the time (minutes) for reaching 260 ° C. in this evaluation test) was measured.
As the ABS resin used in this evaluation test, “Techno ABS330” (MFR = 42 g / 10 min, 220 ° C., 98.0 N) manufactured by Techno Polymer Co., Ltd. was used. Further, as the infrared absorber forming the surface layer 25, “Lumogen IR1050” manufactured by BASF was used as a solution having a concentration of 28 to 32% by mass. Further, a solution containing an infrared absorber is uniformly applied to the inner wall surface 221 of the cavity 22 in the rubber mold 2 with a brush (“Poster Brush No. 1” manufactured by Shobundo Co., Ltd.), dried for 10 minutes, and then about 10-50 μm. A coating film of the surface layer 25 was formed.

In this evaluation test, the cavity 22 of the rubber mold 2 made of silicone rubber is formed into a rectangular shape with a length of 80 mm × width of 55 mm × thickness of 2.5 mm, and heated by a halogen heater to obtain ABS resin. Was measured for the time (melting time) required to reach 260 ° C. from room temperature.
In addition, the ABS resin used in this evaluation test is obtained by freeze-grinding molded thermoplastic resin pellets, sieving them, and small resin particles 62 having a weight average particle diameter of 100 μm or less, and a large weight average particle diameter of 450 μm. Shaped resin particles 61 were obtained.

  As a result of the measurement of the melting time, it was 8 minutes for the invention that is the rubber mold 2 having the surface layer 25, whereas for the comparative product that is the rubber mold 2 that does not have the surface layer 25, It was 32 minutes. From this result, by forming the surface layer 25 containing the infrared absorber on the inner wall surface 221 in the cavity 22 of the rubber mold 2, the time required for melting the thermoplastic resin composition 6A to be molded can be greatly shortened. I understand.

DESCRIPTION OF SYMBOLS 1 Molding apparatus 2 Rubber mold 21 Split mold part 22 Cavity 220 Unfilled cavity part 25 Surface layer 3 Pressure vessel 4 Electromagnetic wave generation means 6A Thermoplastic resin composition 61 Large resin particle 62 Small resin particle 6B Thermoplastic resin composition 60 Plastic molded product

Claims (4)

A rubber mold made of a rubber material and used to heat mold a thermoplastic resin composition filled in a cavity by irradiating an electromagnetic wave including a wavelength region of 0.78 to 2 μm,
The rubber mold for electromagnetic wave irradiation molding, wherein the rubber mold has a surface layer having infrared absorption performance on the inner wall surface of the cavity. ^{2. The} electromagnetic wave irradiation according to claim 1, wherein the surface layer is obtained by applying a liquid containing an infrared absorber, and the amount of the infrared absorber applied is 0.01 to 100 g / m ^2. Rubber mold for molding. A method for molding a resin molded article using the rubber mold for electromagnetic wave irradiation molding according to claim 1 or 2,
An arrangement step of arranging a particulate thermoplastic resin composition in the cavity;
A heating step of irradiating the thermoplastic resin composition in the cavity through the rubber mold with an electromagnetic wave including a wavelength region of 0.78 to 2 μm, and heating and melting the thermoplastic resin composition;
A filling step of filling a molten thermoplastic resin composition into an unfilled cavity portion left in the cavity;
A cooling step of cooling the thermoplastic resin composition in the cavity to obtain a resin molded product.   A resin molded product obtained by the electromagnetic wave irradiation molding method according to claim 3.

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