JP2019077148A - Method for manufacturing injection molded product, and injection molded product - Google Patents

Abstract

To provide an injection molded product having both rigidity and an aesthetic feature.SOLUTION: A method for manufacturing an injection mold product includes the steps of: obtaining a first kneaded product by melting and kneading a thermoplastic resin and a filler; obtaining a second kneaded product by melting and kneading a thermoplastic resin and a flame retardant agent; and dry blending the first kneaded product and the second kneaded product and injection molding. A first shear viscosity of the first kneaded product under a shear rate 1×10/s is larger than the second shear viscosity of the second kneaded product under above mentioned shear rate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing an injection molded article and an injection molded article.

  Generally, resin products used in home appliances, automobiles, office automation equipment and the like are molded by injection molding or the like. In recent years, it has been desired to reduce the amount of resin material used for resin products from the viewpoint of reducing environmental burden and reducing material cost.

  And as a method of reducing the usage-amount of a resin material, the method of forming thinly is known. However, when it is attempted to mold a thin-walled resin product by injection molding, the flowability of the molten resin material in the mold may be reduced. In addition, the thickness of the thinned resin product may decrease.

  In addition to strength, in the above-described home appliances and OA devices, flame retardancy and aesthetics are required. In order to obtain sufficient flame retardancy, it is necessary to add a certain amount or more of the flame retardant, but if the amount of the flame retardant added is increased, the strength decreases.

  On the other hand, as a method of enhancing the strength of a resin product, a method of containing a filler such as glass fiber with respect to a thermoplastic resin is known (see, for example, Patent Documents 1 and 2).

  Patent Document 1 describes a resin composition having a polycarbonate, a phosphazene compound, and a filler. The resin composition described in Patent Document 1 adds a filler after mixing a polycarbonate and a phosphazene compound. In the resin composition described in Patent Document 1, the filler is added in the middle of the production process and distributed throughout, thereby achieving both flame retardancy and rigidity in the injection molded product.

  Patent Document 2 describes a method in which a composition obtained by melt-dipping a reinforced fiber bundle epoxy resin in polycarbonate and a composition containing a crystalline resin and a flame retardant are dry-blended and injection-molded.

JP, 2014-201638, A JP, 2013-209629, A

  However, in the resin composition described in Patent Document 1, since the flame retardant is distributed throughout, there is a risk that the strength of the injection-molded article may be reduced.

  Moreover, in the resin composition described in Patent Document 2, since the reinforcing fiber bundle epoxy resin is only dipped in the polycarbonate, the reinforcing fiber bundle epoxy resin may not be dispersed in the whole, and the strength may not be sufficient. .

  Thus, in the case of thin-walled injection molded products, there is room for consideration from the viewpoint of achieving both flame retardancy, strength and appearance.

  An object of the present invention is to provide an injection molded article having both flame retardancy, strength and aesthetics.

The present invention relates to a method for producing an injection molded article as a means for solving the above problems, comprising the steps of melt-kneading a thermoplastic resin and a filler to obtain a first kneaded product, the thermoplastic resin and the flame retardant Melt-kneading to obtain a second mixture, and dry-blending the first mixture and the second mixture, followed by injection molding, wherein the shear rate is 1 × 10 ³ / sec. The first shear viscosity of the first mixture is greater than the second shear viscosity of the second mixture at the shear rate.

  Further, according to the present invention, an injection-molded article as another means for solving the above-mentioned problems comprises a first kneaded product obtained by melt-kneading a thermoplastic resin and a filler, and melting the thermoplastic resin and the flame retardant. An injection molded article produced by dry blending a second kneaded product obtained by kneading and injection molding, wherein the filler is on the inside of the injection molded article, and the flame retardant is on the outside of the injection molded article. It is ubiquitous.

  According to the present invention, it is possible to provide an injection molded article having high strength, flame retardancy and aesthetic appearance.

It is a figure which shows roughly an example of the manufacturing method of the injection molded article in embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described.

  The manufacturing method of the injection molded product which concerns on one embodiment of this invention mixes a 1st kneaded material and a 2nd kneaded material, and inject-molds the obtained mixture as a material. The first kneaded material and the second kneaded material may be in a form known as an injection molding material. Examples of such forms include pellets, flakes and debris.

  The mixing of the first kneaded material and the second kneaded material may be sufficient if both the kneaded materials are mixed to a uniform composition in the cylinder at the time of injection molding, and the first kneaded material and the second kneading The mixing of the substances can be carried out by the usual methods of mixing the materials in injection molding. The mixing is a dry blend and can be performed using a tumbler. Here, "dry blending" means a mixing method in which materials are directly mixed and mixed without using a medium such as a solvent.

  Moreover, injection molding can be performed on the normal conditions which use a resin material. The conditions for injection molding can be determined as appropriate depending on the type of resin in the first and second kneaded materials.

  The first kneaded product is a melt-kneaded product of a composition containing a thermoplastic resin and a filler. The second kneaded product is a melt-kneaded product of a composition containing a thermoplastic resin and a flame retardant.

  The thermoplastic resin in the first kneaded product and the second kneaded product can be appropriately selected in the range satisfying the requirements for shear viscosity described later. The same thermoplastic resin is used as the thermoplastic resin contained in the first and second kneaded materials. Here, "the same resin" means a resin having the same main chain. For example, resins having merely different molecular weights are the same resin. Moreover, let resin which denatured the terminal atom be the same resin as resin before modification. The fact that the thermoplastic resins contained in the first and second kneaded materials are the same resin means that the requirements for shear viscosity described later can be easily achieved, and the compatibility of both the kneaded materials at the time of injection molding It is preferable from the viewpoint of enhancing.

  Examples of thermoplastic resins include polycarbonate, styrenic resins, polyethylene, polypropylene, polyethylene terephthalate and polybutylene terephthalate. Examples of polycarbonates include aromatic polycarbonates. Examples of styrenic resins include acrylonitrile-butadiene-styrene copolymer (ABS resin), polystyrene (PS) and high impact polystyrene (HIPS).

  As the thermoplastic resin, it is preferable to use an aromatic polycarbonate or a styrenic resin from the viewpoint of mechanical properties such as rigidity and toughness in an injection molded article and cost.

  The filler may be a fibrous filler or a granular filler. Here, “fibrous” means a form having an average thickness of 20 μm or less and an aspect ratio (ratio of major axis / minor axis) of 5 or more. The filler is preferably a fibrous filler from the viewpoint of enhancing the rigidity of the injection-molded article. Fibrous fillers are generally susceptible to loss of smoothness in the appearance of injection molded articles. However, in the present invention, since it is excellent in the effect of suppressing the deterioration of the appearance due to the reason described later, it is more preferable to use a fibrous filler for the improvement of the rigidity. The fibrous filler may be one kind or more.

  The fibrous filler may be broken at the time of melt-kneading at the time of preparing the first kneaded material and at the time of injection molding thereafter. If the length of the fibrous filler is too short, the strength (rigidity) of the injection molded article may be insufficient. On the other hand, when the fibrous filler is too long, the appearance of the injection-molded article tends to be adversely affected, and the appearance may be insufficient. In addition, uniform dispersion of the fibrous filler in the first kneaded product may be insufficient. The average fiber length of the fibrous filler in the injection molded product is preferably 100 μm or more from the viewpoint of achieving sufficient rigidity of the injection molded product, and is 500 μm or less from the viewpoint of the dispersibility of the fibrous filler Is preferred.

  The form of the particulate filler is a non-fibrous shape, and may be, for example, spherical, or may be amorphous as a crushed resin composition. The aspect ratio of the particulate filler may be less than 5, but is preferably 2 or less, more preferably 1.5 or less. The granular filler may be of one kind or more.

  If the filler is too large, the appearance of the injection molded product may be impaired. The size of the granular filler is preferably as small as possible in terms of the appearance and rigidity of the injection-molded article. For example, the average maximum diameter of the particulate filler is preferably 50 μm or less.

  The material of the fibrous filler and the particulate filler can be appropriately selected from inorganic compounds generally used for the filler (aggregate) in the resin composition. The material of the fibrous filler and the material of the granular filler may be the same or different. Examples of filler materials include glass, talc, mica and carbon. Moreover, it is preferable to use glass fiber for a fibrous filler.

  The shape and size of the fibrous filler and the granular filler can be determined by a conventional method for measuring the shape and size of the filler in the resin composition. For example, the shape and size of the filler can be determined by analysis of a magnified image of the cross section of the kneaded or injection molded article.

  The flame retardant may be an organic flame retardant or an inorganic flame retardant. Examples of organic flame retardants include bromo compounds and phosphorus compounds. In addition, examples of the inorganic compounds include antimony compounds and metal hydroxides. The flame retardant is preferably a non-halogenated phosphoric acid compound from the viewpoint of reducing the burden on the environment. The flame retardant may be of one kind or more.

In the first and second kneaded materials, the first shear viscosity of the first kneaded material at a shear rate of 1 × 10 ³ / sec is greater than the second shear viscosity of the second kneaded material at the shear rate. Use each one. That is, the ratio of the first shear viscosity to the second shear viscosity is greater than 1.0. When the ratio is 1.0 or less, the appearance of the injection-molded article tends to be impaired. From the viewpoint of sufficiently expressing both the rigidity and the appearance of the injection-molded article, the ratio is preferably 1.5 or more. If the ratio is too large, the effect of the ratio will plateau, so the upper limit may be appropriately determined within a range where the desired rigidity and aesthetics are sufficiently developed.

  The first shear viscosity and the second shear viscosity can be determined by a conventional method of measuring the shear viscosity of the resin composition. For example, the first shear viscosity and the second shear viscosity can be measured using a Capirograph manufactured by Toyo Seiki Seisaku-sho, Ltd.

  In addition, the first shear viscosity, the second shear viscosity and their ratio can be adjusted by a conventional method of adjusting the shear viscosity of the resin composition. For example, the type of resin material in the first and second kneaded products, the content of the filler in the first kneaded product or the content of the flame retardant in the second kneaded product, and the melt kneading of the first and second kneaded products. It can be adjusted by the condition of.

  The content of the thermoplastic resin, the fibrous filler and the particulate filler in the kneaded product can be determined in accordance with the content in the injection molded product, and the content of the component in the injection molded product is as expected. It can be appropriately determined in the range where the effect can be obtained.

  For example, in the injection-molded article, when the content of the thermoplastic resin in the first kneaded material is too small, the appearance may be impaired due to the relatively large content of the filler. On the other hand, when the content of the thermoplastic resin in the first kneaded material is too large, the content of the filler may be relatively reduced, whereby the rigidity may be insufficient. In addition, when the content of the thermoplastic resin in the second kneaded product is too small, the rigidity of the injection molded product may be insufficient because the content of the flame retardant relatively increases. On the other hand, when the content of the thermoplastic resin in the second kneaded product is too large, the content of the flame retardant relatively decreases, and the flame retardancy of the injection molded product may be insufficient.

  Thus, the content of the thermoplastic resin is 60 to 60 parts of the total amount of the thermoplastic resin, the filler and the flame retardant in the injection molded product, from the viewpoint of enhancing each of the flame retardancy, rigidity and appearance in the injection molded product. It is preferable that it is 90 mass%. The content of the filler is preferably 3 to 25% by mass, and more preferably 5 to 20% by mass, with respect to the total amount of the thermoplastic resin, the filler and the flame retardant in the injection-molded article. Furthermore, the content of the flame retardant is preferably 3 to 50% by mass, and more preferably 5 to 20% by mass, with respect to the total amount of the thermoplastic resin, the filler and the flame retardant in the injection-molded article.

  It is preferable that the mass ratio of the first kneaded product and the second kneaded product (first kneaded product: second kneaded product) is 92: 8 to 50:50, and it is more preferably 90:10 to 60:40. preferable. When the first kneaded material rich in the filler and the second kneaded material rich in the flame retardant are within this range, the second kneaded material covers the first kneaded material, so the appearance is less likely to deteriorate. In addition, since the first kneaded material rich in the filler is more than the second kneaded material rich in the flame retardant, the strength of the injection molded article can be maintained. When the mass ratio of the first and second kneaded materials is out of the above range, the appearance is deteriorated and the strength of the injection-molded article is reduced.

  The injection molded article may further contain other components other than the thermoplastic resin, the flame retardant and the filler as long as the effects of the present embodiment can be obtained. Examples of other ingredients include colorants, UV absorbers and elastomers. The content of these other components in the injection molded product can be appropriately determined in the range in which the effects of the other components can be obtained as well as the effects of the present embodiment. The other components may be added to one of the first and second kneaded materials, or may be added to both.

  In addition, the method for producing an injection-molded article may further include other steps other than the step of obtaining the first kneaded material, the step of obtaining the second kneaded material, and the injection molding step of the obtained mixture. Examples of other steps include a granulation step of processing each of the first and second kneaded materials into a shape for a material for injection molding, and a step of drying a mixture of both kneaded materials prior to injection molding. included. These other steps can be performed under the normal conditions for injection molding of the resin composition, as long as the requirements for the ratio of shear viscosity described above are satisfied.

  The injection molded article obtained by injection molding contains a thermoplastic resin, a filler and a flame retardant, and the filler is unevenly distributed inside and the flame retardant is unevenly distributed outside the filler. The uneven distribution means to exist with a biased distribution. That is, in the injection-molded article, the filler is distributed to the inside of the injection-molded article, and the flame retardant is distributed to the surface side of the injection-molded article. Such a biased distribution may include an increase or decrease of the presence ratio in a predetermined direction, or may not include such an increase or decrease. In addition, a part of the filler may be present on the surface side of the injection molded article, or a part of the flame retardant is present in the inside (central part) of the injection molded article, in the range where the above distribution deviation is observed. It may be done.

  Fillers and flame retardants in injection molded articles can be detected by known techniques. For example, it can be detected by cutting the injection molded article and observing the cross section with a microscope or performing elemental analysis.

  The rigidity and appearance of the injection-molded article can be determined as appropriate depending on the use of the injection-molded article. For example, injection molded articles can be used as structural materials (such as exterior materials and interior materials) of electrical devices such as printers. In applications requiring both such appearance and strength, the injection molded article preferably has a flexural modulus of 3000 MPa or more in order to satisfy the required rigidity, and the required appearance smoothness In order to satisfy (aesthetic), it is preferable to have a ten-point average roughness (Rz) of 6 or less.

  Hereinafter, the present embodiment will be described in more detail with reference to the drawings. FIG. 1 is a schematic view of a method of manufacturing an injection molded article in the present embodiment.

  In the present embodiment, a mixture of the first kneaded product 3a having a large shear viscosity and the second kneaded product 3b having a small shear viscosity (for example, a mixture by dry blending) is used as a material for injection molding. For example, the first kneaded product 3a is produced by melt-kneading the thermoplastic resin 1 and the filler 2a. Similarly, the second kneaded product 3b is produced by melt-kneading the thermoplastic resin 1 and the flame retardant 2b. These kneaded materials are produced, for example, as pellets.

  The first kneaded product 3a and the second kneaded product 3b are sufficiently mixed by a known method for injection molding such as dry blending, and the obtained mixture is introduced into an injection molding machine. In the cylinder of the injection molding machine, both kneaded materials become uniform composition 4, but it is considered that composition 4 contains area 4a rich in filler 2a and area 4b rich in flame retardant 2b. Be

  Since the shear viscosity A of the first kneaded product 3a is higher than the shear viscosity B of the second kneaded product 3b, in the cylinder, the region 4a rich in the filler 2a is higher than that in the region 4b rich in the flame retardant 2b It is also considered to exhibit high viscosity. As a result, in injection molding, when composition 4 is injected along the X direction into molds (not shown) disposed on both sides in the Y direction in the figure, composition 4 is contained in the mold. The fountain flow and the lower viscosity, flame retardant-rich region 4b in the composition 4 is moved to the surface of the mold (the surface of the injection molded article) as compared to the region 4a rich in the filler 2a. Therefore, it is considered that a structure is formed in which the filler 2 b is unevenly distributed inside the injection molded article 5 and the flame retardant 2 b is unevenly distributed outside the injection molded article 5.

  The filler is highly effective in enhancing the rigidity of the injection molded product, but when it is present on the surface of the injection molded product and in the vicinity thereof, the appearance of the injection molded product is deteriorated. On the other hand, although the flame retardant does not easily impair the smoothness of the appearance of the injection molded product, the effect of the filler to increase the rigidity of the injection molded product is extremely small.

  As described above, in the injection molded product according to the embodiment, the flame retardant having little influence on the appearance is unevenly distributed on the surface of the injection molded product and in the vicinity thereof, and the flame retardant having a high effect of enhancing the flame retardancy is an injection molded product It is unevenly distributed in the central part in the opposing direction (Y direction) of the mold in the cross section crossing the injection direction (X direction). Thus, it is considered that the injection molded article having the filler on the inner side exhibits higher rigidity than the case where the flame retardant is also present on the surface of the injection molded article and in the vicinity thereof. In addition, since the particulate filler is unevenly distributed on the surface side of the injection-molded article, the reduction of the appearance due to the fibrous filler is suppressed, and the injection-molded article exhibits the above-mentioned appearance.

  EXAMPLES Hereinafter, the present invention will be specifically described using examples, but the present invention is not limited to the following embodiments.

Example 1
60 parts by mass of polycarbonate and 10 parts by mass of glass fiber are melt-kneaded at a cylinder temperature of 270 ° C. and a screw rotation speed of 250 rpm using a twin-screw kneader (HYPERKTX-30; Kobe Steel, Ltd.) to a diameter of 2 to 3 mm The first kneaded material 1 was obtained as a cylindrical pellet of about 3 to 4 mm in length.

  20 parts by mass of polycarbonate and 10 parts by mass of flame retardant are melt-kneaded using a twin-screw kneader at a cylinder temperature of 270 ° C. and a screw rotational speed of 250 rpm, and cylindrical with a diameter of about 2 to 3 mm and a length of about 3 to 4 mm The second kneaded material 1 was obtained as a pellet of

  The polycarbonate used was “Calibre 301-10 (manufactured by Sumika Stylon Polycarbonate Co., Ltd.)” (“CALIBER” is a registered trademark of Trinseo Europe Ltd.). Hereinafter, the polycarbonate is also referred to as "PC1". Moreover, as glass fiber, "CSF 3 PE-455 (made by Nitto Boseki Co., Ltd.)" was used. The flame retardant used "PX-200 (made by Daihachi Chemical Co., Ltd.)" which is a condensed phosphoric acid type compound.

The shear viscosity at a melt shear rate of 1 × 10 ³ / sec was measured using a capillary rheometer (Capirograph 1D; Toyo Seiki Seisakusho Co., Ltd.) for each of the first kneaded material 1 and the second kneaded material 1. As a result of the measurement, it is confirmed that the shear viscosity (first shear viscosity) of the first kneaded product 1 is larger than the shear viscosity (second shear viscosity) of the second kneaded product 1, and further, the second kneaded product 1 The ratio Rη of the first shear viscosity of the first kneaded product 1 to the shear viscosity was 4.7.

  The first kneaded product 1 and the second kneaded product 1 were dry-blended with a tumbler to obtain a mixture of these pellets. The obtained mixture was dried at 80 ° C. for 4 hours, and then placed in a hopper of an injection molding machine, and injection molded to obtain an injection molded article 1, which is referred to as Example 1. The conditions for the injection molding were a cylinder temperature of 270 ° C., a mold temperature of 80 ° C., an injection speed of 30 mm / sec, and a holding pressure of 50 MPa.

  The shape of the injection molded article 1 conforms to the dimensions described in JIS K7171. That is, the injection-molded article 1 has a rectangular parallelepiped shape of 1.6 mm long, 10 mm wide, and 100 mm long.

Example 2
An injection molded article 2 was obtained as in Example 2 in the same manner as Example 1 except that the polycarbonate of the first kneaded product was changed to 60 parts by mass to 65 parts by mass and the filler was changed from 10 parts by mass to 5 parts by mass. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 4.5.

[Example 3]
An injection molded article 3 was obtained as in Example 3 in the same manner as Example 1 except that the polycarbonate of the first kneaded product was 60 parts by mass to 50 parts by mass and the filler was 10 parts by mass to 20 parts by mass. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 5.5.

Example 4
An injection molded article 4 was obtained as in Example 4 in the same manner as Example 1 except that the polycarbonate of the first kneaded material was changed from 60 parts by mass to 67 parts by mass and the filler was changed from 10 parts by mass to 3 parts by mass. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 4.3.

[Example 5]
An injection-molded article 5 was obtained as in Example 5 in the same manner as in Example 1 except that the polycarbonate of the first kneaded product was 60 parts by mass to 45 parts by mass, and the filler was 10 parts by mass to 25 parts by mass. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 6.0.

[Example 6]
An injection-molded article 6 is obtained in the same manner as in Example 1 except that the polycarbonate of the second kneaded product is 20 parts by mass to 25 parts by mass, and the flame retardant of the second kneaded product is 10 parts by mass to 5 parts by mass. It is referred to as Example 6. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 2.3.

[Example 7]
An injection molded article 7 is obtained in the same manner as in Example 1 except that the polycarbonate of the first kneaded product is 60 parts by mass to 50 parts by mass and the flame retardant of the second kneaded product is 10 parts by mass to 20 parts by mass. It is referred to as example 7. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 6.3.

[Example 8]
An injection molded article 8 was obtained as in Example 8 in the same manner as Example 1 except that the polycarbonate of the second kneaded product was changed to 20 parts by mass to 27 parts by mass and the flame retardant was changed to 10 parts by mass to 3 parts by mass. . Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 1.5.

[Example 9]
Example 1 except that the polycarbonate of the first kneaded product is 60 parts by mass to 50 parts by mass, the polycarbonate of the second kneaded product is 20 parts by mass to 15 parts by mass, and the flame retardant is 10 parts by mass to 25 parts by mass. Thus, an injection-molded article 9 was obtained as in Example 9. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 9.5.

[Example 10]
60 parts by mass to 85 parts by mass of polycarbonate of the first kneaded product, 10 parts by mass to 5 parts by mass of glass fibers, 20 parts by mass to 5 parts by mass of polycarbonate of the second kneaded product, and 10 parts by mass of a flame retardant The injection-molded article 10 was obtained in the same manner as in Example 1 except that the amount of the above was changed to 5 parts by mass to obtain Example 10. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 8.8.

[Example 11]
An injection molded article 11 is obtained in the same manner as in Example 1 except that the polycarbonate of the first kneaded product is 60 parts by mass to 40 parts by mass and the polycarbonate of the second kneaded product is 20 parts by mass to 40 parts by mass. It is set as Example 11. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 2.9.

[Example 12]
Example 1 except that the polycarbonate of the first kneaded product is 60 parts by mass to 82 parts by mass, the polycarbonate of the second kneaded product is 20 parts by mass to 3 parts by mass, and the flame retardant is 10 parts by mass to 5 parts by mass. Thus, an injection-molded article 12 was obtained as in Example 12. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 11.5.

[Example 13]
An injection molded article 13 was obtained as in Example 13 in the same manner as Example 1, except that the thermoplastic resin of the first kneaded product was changed from polycarbonate to ABS resin. Also in this example, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 3.0. As the ABS resin, a commercially available product "Toyolac 700-314 (manufactured by Toray Industries, Inc.)" was used.

Comparative Example 1
An injection-molded article was prepared in the same manner as Example 1, except that 80 parts by mass of polycarbonate, 10 parts by mass of glass fiber, and 10 parts by mass of flame retardant were melt-kneaded together and pellets of the kneaded product were injection molded. C1 was obtained, which is referred to as Comparative Example 1. In Comparative Example 1, the shear viscosity was not measured because the injection molded product C1 was not produced after the step of kneading the first and second kneaded materials.

Comparative Example 2
An injection molded article C2 was obtained as Comparative Example 2 in the same manner as Example 1, except that the polycarbonate of the second kneaded product was changed to 20 parts by mass to 30 parts by mass and no flame retardant was added. In Comparative Example 2, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 1.1.

Comparative Example 3
An injection molded article C3 was obtained in the same manner as in Example 1 except that the amount of the polycarbonate of the first kneaded product was 60 parts by mass to 70 parts by mass, and glass fibers were not added, and it was set as Comparative Example 3. In Comparative Example 3, the shear viscosity of the first kneaded product was larger than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 4.2.

Comparative Example 4
"Calibre 301-22 (made by Sumika Styron Polycarbonate Co., Ltd.)" (hereinafter also referred to as PC2) is used for the polycarbonate of the first kneaded product, and "Calibre 301-6 (Sumitomo Stylon polycarbonate" is used for the polycarbonate of the second kneaded product. An injection molded article C4 is obtained in the same manner as in Example 1 except that 25 parts by mass of “made by Co., Ltd.” (hereinafter referred to as “PC3”) is used and the flame retardant is changed to 10 parts by mass to 5 parts by mass. It was four. In Comparative Example 4, the shear viscosity of the first kneaded product was smaller than the shear viscosity of the second kneaded product, and the shear viscosity ratio Rη was 0.8.

  Viscosity ratio Rη of the first shear viscosity to the second shear viscosity and the composition of the injection molded articles 1 to 13 (Examples 1 to 13) and C1 to C4 (Comparative Examples 1 to 4) (= first shear viscosity / second) The shear viscosity is shown in Table 1.

[Evaluation]
(1) Evaluation of rigidity The bending test according to JIS K7171 was done about each of the injection molded articles 1-13 (Examples 1-13) and C1-C4 (comparative examples 1-4). More specifically, a bending test was performed using a universal material testing machine "Tensilon" manufactured by A & D Co., Ltd., under the measurement conditions of an indentation speed of 2 mm / min and a distance between supporting points of 64 mm. And bending elastic modulus Ef was computed and it evaluated by the following reference | standard.
:: Ef is 3500 MPa or more ○: Ef is 3000 MPa or more and less than 3500 MPa ×: Ef is less than 3000 MPa

(2) Evaluation of Appearance Regarding the injection molded articles 1 to 13 (Examples 1 to 13) and C1 to C4 (Comparative Examples 1 to 4), the surface of the injection molded article was manufactured using VK-X100 manufactured by Keyence Corporation. It observed and analyzed the image of the said surface, and calculated 10 point roughness average Rz. And it evaluated by the following standard.
:: Rz is less than 4 μm ○: Rz is 4 μm or more and less than 6 μm ×: Rz is 6 μm or more

(3) Evaluation of deflection temperature under load The deflection temperature under load was measured according to ISO 75-1 and 2 for each of injection molded articles 1 to 13 (Examples 1 to 13) and C1 to C4 (Comparative Examples 1 to 4). In more detail, HDT tester S3-MH (Toyo Seiki Seisaku-sho, Ltd.) was used, and the load was set to 0.45 MPa. And deflection temperature under load was evaluated by the following standards.
:: temperature is 85 ° C. or more ○: temperature is 80 ° C. or more and less than 85 ° C. ×: temperature is less than 80 ° C.

(4) Evaluation of flame retardancy For evaluation of flame retardancy, injection molded articles 1 to 13 (Examples 1 to 13) for UL test molded to 100 mm × 10 mm × 1.6 m and C1 to C4 (comparative examples) 1 to 4) were used. Flame retardancy is evaluated by adjusting the injection molded articles 1 to 14 and C1 to C5 for 48 hours in a constant temperature room at 23 ° C. and 50% humidity, and defined by UL Underwriters Laboratories (UL) in the United States, UL 94. It was conducted in accordance with the test (combustion test of plastic material for parts of equipment). Here, the “UL 94 test” is a method of evaluating flame retardancy from the afterflame time and drip property after indirectly heating a burner flame for 10 seconds to a resin molding of a predetermined size held vertically. And the flame retardance was evaluated by the following references | standards.
:: V-0
○: V-1, V-2
X: out of specification

(5) Internal Structure The injection molded articles 1 to 13 (Examples 1 to 13) and C1 to C4 (Comparative Examples 1 to 4) were respectively cut into a portion near the surface and other portions, The distribution of the filler remaining after burning the resin of the part of As a result, in the injection molded articles 1 to 13 (Examples 1 to 13), the filler increased as the distance from the surface of the injection molded article increased.

  In the injection-molded articles C1 and C2 (Comparative Examples 1 and 2), the fillers were substantially uniformly distributed. In addition, in the injection-molded article C4 (Comparative Example 4), the filler was more distributed on the surface side.

  Moreover, about each of the injection molded articles 1-13 (Examples 1-13) and C1-C4 (comparative examples 1-4), it cut | disconnects into the part near the surface, and the part other than that, Each part is cut. The distribution of the flame retardant was observed with a microscope. As a result, in the injection molded articles 1 to 13 (Examples 1 to 13), the flame retardant decreased as the distance from the surface of the injection molded article increased.

  In the injection molded articles C1, C3 and C4 (comparative examples 1, 3 and 4), the flame retardants were almost uniformly distributed.

  The evaluation results of Examples 1 to 13 and Comparative Examples 1 to 4 are shown in Table 2.

  As shown in Table 2, it can be seen that the injection molded articles 1 to 13 (Examples 1 to 13) are all sufficient in flexural modulus, deflection temperature under load, flame retardancy and appearance.

  On the other hand, all of the injection molded articles C1, C2 and C4 (comparative examples 1, 2 and 4) were insufficient in flame retardancy and appearance of the surface. For injection molded articles C1 and C4 (comparative examples 1 and 4), the thermoplastic resin, the filler and the flame retardant are collectively melt-kneaded, so the filler is uniformly dispersed and sufficient on the surface of the injection molded article and its vicinity It is believed that the amount was present. Moreover, in the injection molded article C2 (comparative example 2), it is considered that the flame retardant is not contained.

  In addition, in the injection molded product C3 (Comparative Example 3), the filler was not contained, so the flexural modulus and the deflection temperature under load were insufficient.

  According to the present invention, it is possible to obtain an injection molded article which is excellent in rigidity and has a surface appearance smoothness unique to a resin molded article, due to the type of filler and two types of melt-kneaded products having sufficiently different shear viscosities. Be Therefore, according to the present invention, it is expected that the improvement of the productivity of the above-mentioned injection molded product and the further reduction of the environmental load associated with the production thereof can be achieved.

1 thermoplastic resin 2a filler 2b flame retardant 3a first kneaded product 3b second kneaded product 4 composition 4a region rich in filler 4b region rich in flame retardant 5 injection molded article

Claims (12)

Melt-kneading a thermoplastic resin and a filler to obtain a first kneaded product;
Melt-kneading the thermoplastic resin and the flame retardant to obtain a second kneaded product;
Dry blending and injection molding the first kneaded product and the second kneaded product;
Including
The first shear viscosity of the first mixture at a shear rate of 1 × 10 ³ / sec is greater than the second shear viscosity of the second mixture at the shear rate.
Method of manufacturing injection molded articles.   The method for producing an injection molded article according to claim 1, wherein a ratio of the first shear viscosity to the second shear viscosity is 1.5 or more.   The method for producing an injection molded article according to claim 1 or 2, wherein the thermoplastic resin is an aromatic polycarbonate or a styrenic resin.   The method for producing an injection molded article according to any one of claims 1 to 3, wherein the filler is a fibrous filler.   The method for producing an injection molded article according to claim 4, wherein the fibrous filler is glass fiber.   The content of the thermoplastic resin is 60 to 90% by mass, and the content of the filler is 3 to 25% by mass with respect to the total amount of the thermoplastic resin, the filler, and the flame retardant, The method for producing an injection-molded article according to any one of claims 1 to 5, wherein the content of is 3 to 50% by mass.   The manufacturing method of the injection molded product of Claim 6 whose content of the said filler is 5-20 mass%.   The manufacturing method of the injection molded article of Claim 6 or 7 whose content of the said flame retardant is 5-20 mass%.   In the injection molding step, the first kneaded material and the second kneaded material are dry blended so that the mass ratio of the first kneaded material and the second kneaded material is 92: 8 to 50:50, The manufacturing method of the injection molded article as described in any one of Claims 1-8.   10. The injection according to claim 9, wherein the first kneaded material and the second kneaded material are dry blended so that the mass ratio of the first kneaded material and the second kneaded material is 90: 10 to 60: 40. Method of producing a molded article.   The method for producing an injection-molded article according to any one of claims 1 to 10, wherein the flame retardant is a phosphorus-based compound. An injection-molded article produced by injection molding a dry blend of a first kneaded product obtained by melt-kneading a thermoplastic resin and a filler, and a second kneaded product obtained by melt-kneading the thermoplastic resin and a flame retardant. And
The filler is unevenly distributed inside the injection molded article, and the flame retardant is unevenly distributed outside the injection molded article.
Injection molded products.

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