JP3549341B2 - Molding method of molded article made of polymer alloy material - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for molding a molded article made of a polymer alloy material and having excellent gloss.
[0002]
[Prior art]
A mold for molding a molded article based on a polymer alloy material (hereinafter, simply referred to as a mold) usually includes a polymer alloy material (hereinafter simply referred to as a molten metal) that is melted in a cavity which is a hollow portion provided in the mold. (Which may be referred to as a resin), which is not deformed even by a high pressure at the time of filling, for example, carbon steel, stainless steel, aluminum alloy, and copper alloy. Then, by filling the cavity provided in the mold with the molten resin, a surface having a desired shape and constituting the cavity of the mold (hereinafter referred to as a cavity surface of the mold for convenience) is transferred. Obtained molded products.
[0003]
The polymer alloy material used as a raw material resin for molded articles is a material obtained by blending two or more thermoplastic resins, or a block copolymer or a graft copolymer in which two or more thermoplastic resins are chemically bonded. is there. And it is widely used as a high-performance material which can have the unique performance of each of the single thermoplastic resins. Examples of the polymer alloy material include impact-resistant polystyrene (HIPS) resin and modified polyphenylene ether (modified PPE) resin. The HIPS resin is obtained by blending a rubber component such as SBR or BR with the polystyrene resin for the purpose of improving the impact resistance of the polystyrene resin. The impact resistance of the molded product is improved, but the rubber component is blended. As a result, the transparency and gloss of the molded article are lost. Although polyphenylene ether (PPE) resin has excellent heat resistance, it is almost impossible to mold because of poor fluidity. However, by blending the polystyrene resin with the PPE resin, the fluidity is improved and a modified PPE resin that can be molded is obtained. In the modified PPE resin, since the PPE resin and the polystyrene resin are uniformly dispersed, the heat resistance and the fluidity can be changed according to the mixing ratio of both. As described above, the polymer alloying technique is an excellent technique capable of providing a polymer alloy material with performances that cannot be provided by a single resin alone.
[0004]
[Problems to be solved by the invention]
However, in a molded article molded based on a polymer alloy material, the appearance (especially, glossiness) of the molded article generally deteriorates, and in particular, poor appearance tends to occur in a portion where the thickness of the molded article changes or a weld portion. There is a problem. This cause is related to the material of the mold. As described above, the mold is usually made of a metal material having good heat conductivity. Therefore, when the molten polymer alloy material filled in the cavity comes into contact with the cavity surface of the mold, it immediately starts cooling. As a result, a solidified layer is formed on the molten polymer alloy material, resulting in poor transferability and poor gloss.
[0005]
In order to solve such a problem, in general, a method in which a molten polymer alloy material is injected into a cavity at high pressure to force the cavity surface of a mold to be transferred to the surface of a molded product, or Further, a method has been adopted in which the mold temperature is raised to suppress the development of a solidified layer in the molten resin. However, the former method leads to an increase in cost due to an increase in the size of the molding apparatus and an increase in the size and thickness of the mold itself, and stress remains inside the molded product due to high-pressure filling of the molten resin. The problem that the quality of goods falls is generated. In the latter method, the cooling time of the polymer alloy material in the cavity becomes longer because the mold temperature is set close to the load deflection temperature of the polymer alloy material used for molding. As a result, there is a problem that a molding cycle is lengthened and productivity is reduced. Moreover, it is extremely difficult to completely prevent a solidified layer from being formed on the surface of a molded article by these molding methods.
[0006]
Inorganic fibers are not added, that is, using a non-reinforced thermoplastic resin to prevent rapid cooling of the molten thermoplastic resin filled in the cavity, thereby preventing molding defects such as weld marks and flow marks. For the purpose of prevention, techniques for providing or attaching a low heat conductive material to the cavity surface of a mold are disclosed in, for example, JP-A-55-55839, JP-A-61-100425, and JP-A-62-208919. Japanese Patent Application Laid-Open Nos. 5-111937, 5-200789, JP-B-6-35134, and JP-A-6-218768.
[0007]
However, when a nest having low thermal conductivity is simply attached to the cavity surface of the mold using, for example, an adhesive, the following problems occur, and practical use is difficult.
(1) When the clearance between the mold and the nest having low thermal conductivity is small, when the temperature of the mold is repeatedly increased and decreased, the coefficient of linear expansion between the material constituting the mold and the material constituting the nest is reduced. The nest breaks due to the difference.
(2) In the case where the clearance between the mold and the nest having low thermal conductivity is large, if molding is performed for a long period of time, the molten resin enters between the mold and the nest, and burrs are generated on the molded product. Then, there arises a problem that the burrs break the nest at the time of releasing the mold.
[0008]
In addition, since fine craze generated during cutting remains on the outer periphery of the nest having low thermal conductivity, cracks occur on the outer periphery of the nest due to contact with high-temperature and high-pressure molten resin, and the nest is damaged. Problems arise. Therefore, the durability of the whole mold becomes a problem, and mass production of molded products becomes difficult.
[0009]
When trying to prevent rapid cooling of the molten resin by using a heat-resistant plastic nest, such a nest has low rigidity, and furthermore, has a low surface hardness, so if used for a long time, the nest may be deformed, There is a problem that nesting is damaged. Alternatively, there is a nest formed by forming a thin film of ceramic or the like on a metal surface by vapor deposition or the like, but there is a problem that the durability of the thin film is inferior and the thin film is separated from the metal surface. Therefore, such a nest is used only for a test die or a simple die, and cannot withstand long-term use.
[0010]
Another method to prevent rapid cooling of the molten resin is to use high frequency, electricity, steam, etc. to raise the mold temperature before filling the molten resin into the cavity, and use water etc. in the cooling process It is also known to lower the mold temperature to a low temperature. However, this method has many problems such as requiring excessive facilities, inviting high costs and prolonging the molding cycle, and has not been put to practical use at present.
[0011]
Therefore, an object of the present invention is to form a molded article made of a polymer alloy material and having extremely excellent gloss, without generating burrs on the molded article, and faithfully forming the surface constituting the cavity on the molded article. It is an object of the present invention to provide a method of molding a molded article that can be transferred to a surface. Furthermore, an object of the present invention is that the nest is easy to maintain, the nest made of a very brittle material such as ceramic or glass is not damaged during molding, the nest can be used for a long time, and the cavity surface can be used. It is an object of the present invention to provide a method for molding a molded article made of a polymer alloy material, which can surely transfer the state of the surface of a nest constituting the molded article to the surface of the molded article.
[0012]
[Means for Solving the Problems]
To achieve the above object, a method for molding a molded article comprising the polymer alloy material of the present invention comprises:
(A) a mold provided with a cavity for molding a molded article made of a polymer alloy material;
(B) a ceramic or glass nest having a thickness of 0.5 mm to 10 mm, which is disposed inside the mold and constitutes a part of the cavity;
(C) a restraining plate which is attached to the mold and forms a part of the cavity, which suppresses an end of the nest;
Consisting of
The clearance (C) between the nest and the holding plate is 0.001 mm to 0.03 mm (0.001 mm ≦ C ≦ 0.03 mm), and the holding allowance (ΔS) of the holding plate with respect to the nest is 0.1 mm. Using a mold assembly having the above (ΔS ≧ 0.1 mm),
After filling the polymer alloy material into the cavity, the polymer alloy material is cooled and solidified.
[0013]
When the thickness of the nest is less than 0.5 mm, the heat insulation effect by the nest is reduced, and the molten resin introduced into the cavity is rapidly cooled. As a result, the development of the solidified layer cannot be suppressed, and the gloss from the surface of the molded article becomes less. Lost. Further, the probability of appearance defects such as weld marks and flow marks increases. Further, the transferability of the cavity of the nest to the surface of the molded product is deteriorated, and the mirror surface of the surface of the molded product is deteriorated. When the nest is fixed to the mold, the nest may be bonded to the mold using, for example, a thermosetting adhesive. However, when the thickness of the nest is less than 0.5 mm, the thickness of the adhesive may be reduced. When the resin is not uniform, a non-uniform stress remains in the nest, so that the surface of the molded product may undulate or the nest may be damaged by the pressure of the filled molten resin. On the other hand, when the thickness of the nest exceeds 10 mm, the heat insulation effect of the nest becomes too large, and if the cooling time of the resin in the cavity is not extended, the molded article may be deformed after the molded article is taken out from the mold. . Therefore, a problem such as extension of the molding cycle may occur. In addition, by using such a nest, a molded product can be molded at a constant mold temperature, no special equipment is required, and the molding cycle is equivalent to that of normal molding. The thickness of the nest is preferably 1 mm to 7 mm, more preferably 2 mm to 5 mm.
[0014]
In the molding method of the present invention, the clearance (C) between the insert and the holding plate is 0.001 mm or more and 0.03 mm or less (0.001 mm ≦ C ≦ 0.03 mm), more preferably 0.003 mm to 0 mm. 0.03 mm (0.003 mm ≦ C ≦ 0.03 mm). Here, the clearance (C) is a gap between the nest and the holding plate measured in the thickness direction of the nest (the direction perpendicular to the cavity surface of the nest). More specifically, the minimum value of the clearance (C) is such that when the holding plate is attached, fine cracks are generated on the outer periphery of the nest, or when the nest thermally expands when the temperature of the mold rises, the nest and the holding plate become The stress may be applied to the fine cracks on the outer peripheral portion of the nest so that the nest may be damaged, or the nest may be damaged by an impact at the time of mold clamping. On the other hand, if the clearance (C) exceeds 0.03 mm, the molten resin may enter between the nest and the holding plate, causing cracks in the nest and causing burrs on the molded product.
[0015]
When the holding allowance (ΔS) is less than 0.1 mm, the craze generated at the end of the nest during the production of the nest comes into contact with the molten resin, so that the craze grows into a crack and the nest may be damaged. The upper limit of the suppression allowance (ΔS) is not particularly limited, but is preferably about 2 mm. Here, the holding allowance (ΔS) is the distance from the end surface (side surface) of the holding plate to the end portion (side surface) of the nest measured along a direction parallel to the cavity surface of the nest.
[0016]
The clearance (D) between the nest mounting portion provided in the mold and the nest may be a value as close as possible to zero, but is practically preferably 0.005 mm or more. Here, the clearance (D) refers to the clearance between the nest mounting portion of the mold and the end surface (side surface) of the nest measured along a direction parallel to the cavity surface of the nest. Although it depends on the linear expansion coefficient of the material forming the nest, if the clearance (D) is too small, the breakage of the nest due to the difference between the linear expansion coefficient of the material forming the nest mounting portion of the mold and the material forming the nest may be reduced. It may not be possible to prevent it. Therefore, the clearance (D) may be set to a value that does not cause such a problem. Note that if the clearance (D) is too large, the nesting may be damaged due to the positional deviation of the nesting and insufficient positional stability. Therefore, the clearance (D) is preferably about 2 mm or less.
[0017]
Usually, the mold is composed of a fixed mold part and a movable mold part. Depending on the shape of the molded article to be molded (hereinafter sometimes simply referred to as molded article), required surface characteristics, and the like, the nest may be provided only in the movable mold part, or may be fixed metal. It may be arranged only on the mold part, or may be arranged on both the movable mold part and the fixed mold part. The part of the mold to which the nest is attached may be constituted by a core attached to the mold. In addition, it is preferable that the nest is disposed in a mold, for example, facing a surface portion of a molded product requiring excellent smoothness (mirror surface).
[0018]
Note that forming a part of the cavity means forming a cavity surface that defines the outer shape of the molded product. More specifically, the cavities include, for example, a surface forming a cavity formed in a movable mold portion and a fixed mold portion, a surface forming a cavity formed in a nest, and a cavity formed in a holding plate. And the surface that constitutes. In addition, the surface which comprises these cavities is hereafter called a cavity surface.
[0019]
The thermal conductivity of the nest is 2 × 10^-2It is preferably at most cal / cm · sec · deg. Nesting is wide, zirconia-based material, alumina-based material, K₂O-TiO₂Or a glass selected from the group consisting of soda glass, quartz glass, heat resistant glass, and crystallized glass, and more specifically, ZrO.₂, ZrO₂-CaO, ZrO₂-Y₂O₃, ZrO₂-MgO, K₂O-TiO₂, Al₂O₃, Al₂O₃-TiC, Ti₃N₂And 3Al₂O₃-2SiO₂Or a glass selected from the group consisting of soda glass, quartz glass, heat resistant glass and crystallized glass, with a thermal conductivity of 2 × 10^-2cal / cm · sec · deg or less, ZrO₂-Y₂O₃Or 3Al₂O₃-2SiO₂Is preferably made of a ceramic consisting of 2 × 10^-2When a nest is manufactured using a material having a thermal conductivity exceeding cal / cm · sec · deg, the molten resin in the cavity is rapidly cooled by the nest, so that the nest is manufactured from ordinary carbon steel or the like without the nest. There is a case where only the same appearance as that of a molded article molded by a molded die is obtained, and there is a possibility that the development of a solidified layer cannot be suppressed.
[0020]
Alternatively, it is preferable that the nest is made of crystallized glass having a crystallinity of 10% or more, more preferably 60% or more, more preferably 70 to 100%. When the degree of crystallinity is 10% or more, the crystals are uniformly dispersed throughout the glass, so that the thermal shock strength and interfacial peeling property are dramatically improved, so that the occurrence of nest breakage during molding of the molded product is significantly reduced. Can be. When the degree of crystallinity is less than 10%, there is a disadvantage that interface separation easily occurs from the surface during molding. In addition, the surface roughness R of the nested cavity surface_maxIs 0.03 μm or less, and the linear expansion coefficient of the crystallized glass constituting the nest is 1 × 10^-6/ Deg or less, and the thermal shock strength is preferably 400 ° C. or more.
[0021]
The thermal shock strength is defined as the temperature at which a glass of 100 mm × 100 mm × 3 mm heated to a predetermined temperature is thrown into water at 25 ° C. to determine whether or not the glass breaks. The thermal shock strength of 400 ° C. means that when 100 mm × 100 mm × 3 mm glass heated to 400 ° C. is thrown into water at 25 ° C., no breakage occurs in the glass. The thermal shock strength of the heat-resistant glass is only about 180 ° C. Therefore, when the resin melted at a higher temperature (for example, about 300 ° C.) comes into contact with the nest, the nest may be distorted and the nest may be damaged. The thermal shock strength is also related to the degree of crystallinity of the glass. If the nest is made of crystallized glass having a degree of crystallization of 10% or more, the nest can be reliably prevented from being broken during molding.
[0022]
Here, crystallized glass means that a small amount of TiO₂And ZrO₂Is melted at a high temperature of 1600 ° C. or more, then molded by press, blow, roll, cast, etc., and further heat-treated for crystallization, and Li is added to the glass.₂O-Al₂O₃-SiO₂An example is a crystal in which a main crystal phase is grown and β-eucryptite-based crystals and β-spodumene-based crystals are formed. Alternatively, CaO-Al₂O₃-SiO₂After melting the system glass at 1400-1500 ° C., it was transferred into water and crushed to reduce the size of the particles, then accumulated, formed into a plate on a refractory setter, and further subjected to a heat treatment to obtain β-wollastonite. Examples in which a crystal phase is generated can be given. Furthermore, SiO₂-B₂O₃-Al₂O₃-MgO-K₂Heat treatment of OF-based glass to produce mica crystals, MgO-Al containing nucleating agent₂O₃-SiO₂An example is a glass in which cordierite crystals are generated by heat-treating a system glass. Incidentally, as the nest in the present invention, it is preferable to use a crystallized glass having a β-eucryptite-based crystal or a β-spodumene-based crystal having excellent strength and thermal properties.
[0023]
In these crystallized glasses, the ratio of crystal particles present in the glass substrate can be represented by an index called crystallinity. Then, the degree of crystallinity can be measured by measuring the ratio between the amorphous phase and the crystalline phase using an analytical instrument such as an X-ray diffractometer.
[0024]
In the case where the nest is made of ceramic, at least one thin film layer made of the material constituting the nest may be provided on the surface of the nest by a surface treatment technique such as ion plating. It can be filled, and the surface characteristics of the molded article can be further improved.
[0025]
When the nest is made of ceramic, a convex protrusion may be transferred to the surface of the molded product because the nest material is porous. However, crystallized glass has the advantage that the surface of the molded article is easily mirror-finished because the crystal particles are fine, the adhesion between the particles is excellent, and the glass is not porous.
[0026]
If the molded product requires mirror surface, the surface roughness R of the nested cavity surface_maxIs desirably 0.03 μm or less. Surface roughness R_maxExceeds 0.03 μm, the mirror finish may be insufficient, and the properties required for the molded product, for example, the surface smoothness (image clarity) may not be satisfied. To do so, the surface roughness R_maxIs reduced to 0.03 μm or less, for example, diamond lapping may be performed, and if necessary, lapping with cerium oxide may be performed. Lapping can be performed using a lapping machine or the like. Compared with the polishing of ordinary carbon steel or the like, for example, in the case of crystallized glass, a mirror surface can be obtained at about half the cost, so that the manufacturing cost of the mold assembly can be reduced. The surface roughness R_maxWas measured according to JIS B0601. In the case of molding a molded article having a matte or Heller line surface, fine irregularities or lines may be formed on the nested cavity surface by sandblasting or etching the nested cavity surface.
[0027]
Further, the nesting is performed when the coefficient of linear expansion is 12 × 10^-6It is preferable to manufacture from ceramic or glass of / deg or less. Here, the linear expansion coefficient is an average value at 50 ° C. to 300 ° C. Thereby, deformation and breakage of the nest due to expansion and contraction of different materials such as a mold and a nest can be effectively prevented. For example, when a molded product is molded by mounting a nest on a metal steel mold (in some cases, a core), the mold and the nest are formed by the heat of the molten resin and the heat of water, oil, or the like of a mold temperature controller. Both thermally expand. Therefore, when the linear expansion coefficient exceeds the above value, unless the clearance (D) between the nest mounting portion provided on the mold and the nest is considerably increased, the nest is damaged due to the difference in the linear expansion coefficient. There are cases. When the nest is made of crystallized glass, the coefficient of linear expansion is 1 × 10^-6/ Deg or less.
[0028]
In the molding method of the present invention, the material constituting the nest can be easily processed to have irregularities, curved surfaces, and the like by ordinary grinding, and a nest having any shape other than a considerably complicated shape can be manufactured. A nest can be produced by placing a ceramic powder or a molten glass in a molding die, press-molding and heat-treating. In addition, a nest can be produced by naturally shaping a plate-like object made of glass in a furnace while leaving it on a jig. The lapping process can be easily performed in the final step.
[0029]
When molding a molded product having a curved surface, the nest mounting portion of the mold is processed and suppressed according to the curvature of the back surface of the nest (the surface opposite to the cavity surface of the nest and facing the mold). The plate may also be ground in accordance with the curvature of the nested cavity surface. If such processing is not performed, the nest may be deformed and damaged by the pressure of the molten resin filled in the cavity. Also in this case, the nest is mounted on the nest mounting portion of the mold while maintaining the relationship of ΔS ≧ 0.1 mm and 0.001 mm ≦ C ≦ 0.03 mm, and the nest is held down by a plate.
[0030]
After processing into a predetermined shape by grinding or the like, if there is no risk that the nest will fall from the nest mounting part provided inside the mold when mounting the nest and there is no risk of breakage, or nest the nest without using an adhesive. When the nest can be mounted on the mounting portion, the nest can be directly mounted on the nest mounting portion provided inside the mold without using an adhesive. Alternatively, the nest may be bonded to the nest mounting portion using a thermosetting adhesive selected from an epoxy-based, urethane-based, acrylic-based, silicon-based, or the like. However, it is desirable to make the thickness of the adhesive as thin and uniform as possible in order to prevent the nest from being distorted due to the uneven thickness of the adhesive.
[0031]
Also, when the nest made by hot bending of the glass is mounted on the mold, the end face of the nest is inevitably not parallel to the side wall of the nest mounting part of the mold, but the nest and the nest mounting part of the mold are inevitable. The nest may be mounted on the mold with the clearance (D) between the dies being in the range of 2 mm or less, while paying attention to the occurrence of breakage of the end of the nest. It is also conceivable to grind the end face of the nest made of glass after hot bending to make it parallel to the side wall of the nest mounting part of the mold.However, since a sharply processed edge portion occurs in the nest, There is a possibility that the nest will be damaged when mounted on the mold. Therefore, it is desirable to cut the side wall of the nest mounting portion of the mold so as to be parallel to the end surface of the nest.
[0032]
The polymer alloy material is formed by blending at least two kinds of thermoplastic resins or a block copolymer or a graft copolymer in which two kinds of thermoplastic resins are chemically bonded.
[0033]
As thermoplastic resins constituting a polymer alloy material in which at least two kinds of thermoplastic resins are blended, styrene resins such as polystyrene resin, ABS resin, AES resin and AS resin; polyolefin resins such as polyethylene resin and polypropylene resin; methacrylic resin Polycarbonate resins; polyamide resins such as polyamide 6, polyamide 66 and polyamide MXD6; modified PPE resins; polyester resins such as polybutylene terephthalate resin and polyethylene terephthalate resin; polyoxymethylene resins; polysulfone resins; polyimide resins; polyphenylene sulfide resins; Polyarylate resin; Polyether sulfone resin; Polyether ketone resin; Polyether ether ketone resin; Polyester carbonate resin; Chromatography; elastomers, and the like. As a polymer alloy material in which two kinds of thermoplastic resins are blended, a polymer alloy material of a polycarbonate resin and an ABS resin can be exemplified. Incidentally, such a combination of resins is referred to as polycarbonate resin / ABS resin. The same applies to the following. Further, as a polymer alloy material in which at least two kinds of thermoplastic resins are blended, polycarbonate resin / PET resin, polycarbonate resin / PBT resin, polycarbonate resin / polyamide resin, polycarbonate resin / PBT resin / PET resin, modified PPE resin / HIPS Resin, modified PPE resin / polyamide resin, modified PPE resin / PBT resin / PET resin, modified PPE resin / polyamide MXD6 resin, polyoxymethylene resin / polyurethane resin, PBT resin / PET resin, polycarbonate resin / liquid crystal polymer. be able to. Further, as a polymer alloy material composed of a block copolymer or a graft copolymer in which at least two kinds of thermoplastic resins are chemically bonded, HIPS resin, ABS resin, AES resin, and AAS resin can be exemplified. The polymer alloy material may contain stabilizers, ultraviolet absorbers, release agents, dyes and pigments, and further, glass fibers, glass beads, carbon fibers, wollastonite, aluminum borate whiskers, titanium Inorganic fibers or inorganic fillers such as potassium whisker, basic magnesium sulfate whisker, calcium silicate whisker, calcium sulfate whisker, mica, kaolin, calcium carbonate and the like, or organic filler can also be added.
[0034]
Generally, in order to prevent the molded product from warping due to the shrinkage of the resin after molding, take out the molded product in consideration of the thermal conductivity and thickness of the fixed mold portion and the movable mold portion and the nest. It is desirable to minimize the temperature difference between the fixed mold part and the movable mold part at the time.
[0035]
In the molding method of the present invention, examples of the method of molding a molded article include an injection molding method and a blow molding method, which are generally used for molding a polymer alloy material, and a multicolor molding method. The method is an injection molding method.
[0036]
In the molding method of the present invention, since the mold assembly including the insert and the holding plate is used, the quenching of the molten polymer alloy material filled in the cavity can be eased. Therefore, even at a low mold temperature, it is possible to reliably and easily mold a molded article having excellent mirror surface properties, and to suppress the formation of a solidified layer. Can be granted. In addition, since the quenching of the molten polymer alloy material can be reduced, the fluidity of the resin is improved, so that the injection pressure of the molten polymer alloy material can be set low, and the stress remaining in the molded article can be reduced. As a result, the quality of the molded product is improved. Further, since the injection pressure can be reduced, for example, the thickness of the mold can be reduced, the size of the molding device can be reduced, and the manufacturing cost of the molded product can be reduced.
[0037]
When molding was performed at a mold temperature of 80 ° C. using a mold made of carbon steel using a polymer alloy material, poor gloss occurred on the surface of the molded product. In the molding method of (1), the surface of the molded article had extremely excellent gloss even at the same mold temperature.
[0038]
If the nest is made of a material having a low coefficient of thermal expansion, the nest is manufactured independently of the mold and disposed inside the mold. Easy. If the nest is made of crystallized glass, a nest that has a low coefficient of linear expansion, is resistant to thermal shock, and is less likely to be damaged or cracked can be manufactured. By using such a nest, the heat insulation effect by the nest is large, rapid cooling of the molten resin in the cavity can be suppressed, and appearance defects such as weld marks and flow marks can be effectively prevented from occurring. . In addition, since the nesting is suppressed by the holding plate within the predetermined clearance (C) and holding allowance (ΔS), the appearance of the end of the molded product is not impaired, and burrs are generated at the end of the molded product. And the molten resin does not come into contact with the fine craze remaining on the outer peripheral portion of the nest, thereby preventing breakage of the nest.
[0039]
【Example】
Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings.
[0040]
FIG. 1A is a schematic partial end view showing a mold assembly suitable for molding a molded product in the first embodiment. 1 (B) and 1 (C) are schematic end views of the mold assembly being assembled. Here, the mold assembly is assembled in the order of FIG. 1 (B), FIG. 1 (C), and FIG. 1 (A). In the example, the nest 30 was manufactured by grinding crystallized glass having a crystallinity of 70%. The specifications of the nest 30 are shown in Table 1 below.
[0041]
[Table 1]
Material: crystallized glass composed of spodumene-based crystal (N-0, manufactured by NEC Corporation)
Crystallinity: 70%
Density: 2.51 g / cm³
Thermal conductivity: 0.4 × 10^-2cal / cm · sec · deg
Linear expansion coefficient: -6.0 × 10^-6/ Deg
Thermal shock temperature: 800 ° C
[0042]
The fixed mold part 10 was made of carbon steel S55C. Cutting was performed so that the inner size was 271.20 mm × 81.20 mm and the depth was 4.02 mm, and the nesting portion 11 was provided on the fixed mold portion 10. The cavity surface 31 of the nest 30 having a thickness of 4.00 mm, a length of 271.00 mm, and a width of 81.00 mm is polished and finished using a diamond grindstone and a cerium oxide grindstone to form a cavity surface 31 of the nest 30. Surface roughness R_maxWas set to 0.02 μm. Then, the nest 30 was bonded and fixed in the nest mounting portion 11 using a two-component curing type epoxy adhesive (not shown) (see FIG. 1B). After the adhesion and fixing, the clearance (D) between the nest 30 and the nest mounting portion 11 was measured using a gap gauge, and the minimum clearance was 0.05 mm.
[0043]
The inner dimension of the holding plate 32 made of carbon steel S55C was 270.00 mm × 80.00 mm. Then, the holding plate 32 was fixed to the fixed mold part 10 using screws (not shown). The clearance (C) between the nest 30 and the holding plate 32 was 0.019 mm on average. Further, the holding allowance (ΔS) of the holding plate 32 with respect to the insert 30 was 0.5 mm. The movable mold part 20 and the fixed mold part 10 produced by cutting from carbon steel S55C were assembled to complete a mold assembly. The dimensions of the cavity 40 are 270.00 mm × 80.00 mm and thickness 2.00 mm, and the size of the obtained molded product is 270 mm × 80 mm and thickness 2 mm.
[0044]
The completed mold assembly was attached to an injection molding device. After heating to 130 ° C. using a mold temperature controller and then rapidly cooling to 40 ° C., no problems such as cracks occurred in the nest 30 made of crystallized glass.
[0045]
The mold assembly was heated to 80 ° C. using a 150 MST injection molding device manufactured by Mitsubishi Heavy Industries, Ltd. as the injection molding device. Using a modified PPE resin (AH20 manufactured by Mitsubishi Engineering-Plastics Co., Ltd.) which is a polymer alloy material as a raw material resin, an amount sufficient to completely fill the cavity 40 under the injection molding conditions shown in Table 2 below. The molten resin was injected into the cavity 40 through the gate part 12. After a lapse of 20 seconds from the completion of the injection, the molded product was taken out of the mold assembly. The surface of the molded article has gloss up to its end, and as a result of measuring the glossiness of the molded article surface with a digital deflection angle glossmeter (UGV-5D manufactured by Suga Test Instruments), 99% was obtained. And had very high gloss. Although molding was continuously performed for 10,000 shots, no damage such as cracks occurred in the insert 30.
[0046]
[Table 2]
Molding condition
Mold temperature: 80 ° C
Resin temperature: 280 ° C
Injection pressure: 600kgf / cm²-G
[0047]
(Comparative Example 1)
In Comparative Example 1, a mold was manufactured from a Starbucks steel, and a mold assembly in which the cavity surface of the mold was mirror-polished was used. The structure of the mold assembly of Comparative Example 1 has the same structure as that of the mold assembly of the embodiment, except that the mold assembly is not provided with a nest and a holding plate. FIG. 2A shows a schematic end view of the mold assembly in Comparative Example 1. Then, injection molding was performed using the same polymer alloy material as in Example 1.
[0048]
The flow of the molten resin in the cavity 40 was poor, and the cavity 40 could not be completely filled with the molten resin. Therefore, the injection pressure is set to 100 kgf / cm²-G increase, 700kgf / cm²Molding was performed as -G. The surface of the obtained molded article had poor glossiness, and flow marks were generated. As a result of measuring the glossiness in the same manner as in the example, the glossiness was extremely low at 22%.
[0049]
(Comparative Example 2)
In Comparative Example 2, as shown in a schematic partial end view of FIG. 2B, a mold assembly in which the pressing plate 32 was removed from the mold assembly described in the example was used. Then, injection molding was performed under the same conditions as in the example. The appearance of the end of the obtained molded product was ugly, and burrs and the like were generated. In addition, cracks occurred at the end of the insert 30 in 15 cycles of molding.
[0050]
(Comparative Example 3)
In Comparative Example 3, the clearance (C) between the holding plate 32 and the insert 30 in the mold assembly described in the example was 0.04 mm. Then, injection molding was performed under the same conditions as in the example. As a result, the molten resin penetrated into the gap between the holding plate 32 and the insert 30, and the molded product could not be removed from the mold assembly during mold release.
[0051]
(Comparative Example 4)
In Comparative Example 4, injection molding was performed under the same conditions as in the example, using the same mold assembly as in the example, except that the holding allowance (ΔS) of the holding plate 32 with respect to the insert 30 was set to 0.05 mm. Was. As a result, cracks grew from the outer peripheral portion of the insert 30 and cracks occurred on the entire insert at the fifth cycle of molding.
[0052]
Although the present invention has been described based on the preferred embodiments, the present invention is not limited to these embodiments. The molding conditions and materials used in each embodiment are merely examples, and the structure of the mold assembly is also an example, and can be changed as appropriate. The shapes and sizes of the nesting and the holding plate are also examples, and the design can be changed as appropriate depending on the shape of the molded product to be molded. The nesting and the holding plate may be provided on the movable mold part or on both the fixed mold part and the movable mold part as necessary.
[0053]
【The invention's effect】
By the method for molding a molded article made of the polymer alloy material of the present invention, the gloss of the molded article is extremely improved, and a molded article having excellent mirror surface properties can be easily obtained. Further, since the wettability between the molten resin and the nested cavity surface can be increased, high transferability of the cavity surface can be obtained, and the molded product can be easily released from the mold.
[0054]
Moreover, in the mold assembly of the present invention, the nesting is suppressed by the holding plate within the range of the predetermined clearance (C) and the holding allowance (ΔS), so that the nesting can be performed even if long-term molding is performed. A molded article having a mirror surface can be manufactured easily and inexpensively without breakage. In addition, the appearance of the end of the molded article is not impaired, the occurrence of burrs at the end of the molded article can be prevented, the rejection rate of the molded article can be reduced, and homogenization and high quality can be achieved. The manufacturing cost can be reduced. Furthermore, since the flowability of the molten resin is improved, the injection pressure of the molten resin can be set low, so that the stress remaining on the molded product can be reduced and the quality of the molded product can be improved. I do. Further, since the injection pressure can be reduced, the thickness of the mold can be reduced, the size of the molding device can be reduced, and the production cost of the molded product can be reduced. In addition, by forming a nest from crystallized glass, a molded product excellent in mirror surface property and transferability can be easily obtained. Moreover, if the nest is made of crystallized glass, a nest that has a low linear expansion coefficient, is resistant to thermal shock, and is less likely to be damaged or cracked can be manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic partial end view of a preferred embodiment of a mold assembly suitable for practicing the present invention, and a schematic partial end view of the mold assembly during assembly.
FIG. 2 is a schematic partial end view of a mold assembly in a comparative example.
[Explanation of symbols]
10 Fixed mold part
11 Nesting part
12 Gate section
20 Movable mold part
30 nesting
31 Nested Cavity Surface
32 Holding plate
40 cavities

Claims (5)

(A) a mold provided with a cavity for molding a molded article made of a polymer alloy material;
(B) a ceramic or glass nest having a thickness of 0.5 mm to 10 mm, which is disposed inside the mold and constitutes a part of the cavity;
(C) a holding plate which is attached to the mold and forms a part of the cavity, which suppresses an end of the nest;
Consisting of
A clearance between the nest and the holding plate is 0.001 mm to 0.03 mm, and a mold assembly having a holding allowance of the holding plate with respect to the nest of 0.1 mm or more is used.
A method for molding a molded article made of a polymer alloy material, comprising filling a polymer alloy material into a cavity, and then cooling and solidifying the polymer alloy material. The method for molding a molded article made of a polymer alloy material according to claim 1, wherein the nest has a thermal conductivity of 2 × 10 ⁻² cal / cm · sec · deg or less. _{Nesting, ZrO 2, ZrO 2 -CaO,} ZrO 2 -Y 2 O 3, ZrO 2 -MgO, K 2 O-TiO 2, Al 2 O 3, Al 2 O 3 -TiC, Ti 3 N 2 and 3Al ₂ O ₃ ceramic selected from the group consisting of -2SiO _2, or, or claim 1, characterized in that soda glass, quartz glass, and is fabricated from a glass selected from the group consisting of heat-resistant glass, and crystallized glass A method for molding a molded article comprising the polymer alloy material according to claim 2. _Nested ceramic consisting ZrO 2 _-Y 2 _{O 3} or _3Al 2 _O 3 -2SiO _2, or method of molding a molded article composed of a polymer alloy material according to claim 3, characterized in that it consists of crystallized glass . The polymer alloy material is a blend of at least two kinds of thermoplastic resins or a block copolymer or a graft copolymer in which two kinds of thermoplastic resins are chemically bonded. A method for molding a molded article comprising the polymer alloy material according to any one of claims 1 to 4.

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