JP2007284647A - Resin molded product for painting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin molded product by molding a polyamide resin composition that retains satisfactory electroconductivity since including a large amount of electroconductive fiber, in addition, has excellent surface property, excellent coating adherence in no need of the primer treatment. <P>SOLUTION: The resin molded product for painting is obtained by molding the resin composition comprising the following components (A) to (C): the component (A), 55 wt.% to less than 88 wt.% of at least one selected from the group consisting of polyamide 6 resin, polyamide 66 resin or their mixture or copolymer, having a ISO viscosity number of 80-160 ml/g; the component (B), 11 to 35 wt.% of conductive fiber; and the component (C), 0.1 to 10 wt.% of ethylene-vinyl alcohol copolymer and/or partially saponified ethylene-vinyl acetate copolymer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin molded article for coating, which is made of a specific resin composition and is provided with a coating film on at least a part of its surface. Specifically, the present invention relates to a coating resin molded body that can provide a coated resin molded body having excellent coating adhesion, conductivity and appearance without providing a primer layer or the like on the resin surface. is there.

  Polyamide resin (hereinafter sometimes abbreviated as “PA”) is a variety of engineering plastics (engineering plastics) that utilize its excellent moldability, mechanical properties, chemical resistance, etc. It is widely used as a material for electrical and electronic parts, automobile parts and various structural parts. Among these parts, when used for various covers, housings, exterior panels, switches, etc., there are cases where coating is applied for the purpose of improving design and functionality.

  However, the polyamide resin has a problem that the coating adhesion is lower than other engineering plastics. For this reason, when coating the surface of a molded body made of polyamide resin, generally, a preliminary process for providing a primer layer (adhesive paint) or the like in advance is necessary. Therefore, from the viewpoint of productivity improvement and reduction of environmental load substances, a polyamide resin composition having excellent paint adhesion without requiring primer coating has been desired.

  Conventionally, as a method for improving the coating adhesion of polyamide resin, for example, a method of blending an epoxy compound has been performed. However, the epoxy compound has a problem that it reacts with the polyamide resin even in a small amount to reduce the fluidity of the resin composition. On the other hand, since the effect of improving paint adhesion cannot be obtained unless a large amount of epoxy compound is blended, the epoxy compound-blended polyamide resin composition having excellent paint adhesion is remarkably low in fluidity. There has been a problem that the material is restricted in shape.

  Such a low-fluidity polyamide resin may be used by adjusting the shape, molding conditions, etc. of the resin molded body when it does not contain, for example, a reinforcing agent such as a fibrous substance or a conductive component. There was a problem that its use range was very limited. Furthermore, in a polyamide resin composition containing a fibrous substance such as carbon fiber, the fibrous substance floats on the surface of the resin molded body due to a decrease in fluidity, and the surface property of the resin molded body is deteriorated. There is a problem that the surface property of the coating film is lowered when the film is provided, so that prior primer treatment or the like is essential.

  For these problems, for example, a method of improving the paint adhesion by blending a large amount of other resins having good paint adhesion is known. Specifically, for example, a PA / PPE (polyphenylene ether) resin composition (see, for example, Patent Document 1), a PA / ABS (acrylic butadiene-styrene copolymer) resin composition (for example, see Patent Document 2), and the like. Is mentioned.

In general, electrostatic coating is often used as a method for coating the surface of the polyamide resin, and imparting such conductivity to the polyamide resin is performed. The level of electrical conductivity required for the resin composition to be electrostatically coated is generally at least 10 ⁸ Ω · cm level for the volume resistance in the core phase of the molded body and at least 10 for the surface resistivity of the molded body. ¹¹ Ω level.

  In order to impart conductivity to the polyamide resin, for example, an antistatic agent such as an ionic surfactant or a nonionic surfactant, or a carbon-based material such as conductive carbon black, hollow carbon fibril, carbon fiber, or graphite. In addition, metal powders, metal fibers, and the like are mixed with metal coating materials, and techniques for improving the conductivity of polyamide resins have also been proposed.

  For example, a specific conductive carbon black (C), an inorganic filler (an alloy of a polyamide resin (A) and an ethylene / α-olefin copolymer (B) graft-modified with α, β-unsaturated carboxylic acid ( D), a resin composition containing an ethylene / vinyl alcohol copolymer and / or a partially saponified product (E) of an ethylene / vinyl acetate copolymer has been proposed (see, for example, Patent Document 3).

  A copolymer of olefins and a compound having both an unsaturated group and a polar group is added to 100 parts by weight of a resin composition comprising 90 to 99.9% by weight of a polyamide resin and 0.1 to 10% by weight of a conductive substance. A thermoplastic resin composition containing 1 to 15 parts by weight has been proposed (see, for example, Patent Document 4).

  In general, conductive carbon black is widely used for the purpose of imparting conductivity to a resin, but it is difficult to handle due to its high bulk density, and it is difficult to increase the mixing ratio with the resin. As the mixing ratio to the resin increases, there is a problem that the fluidity of the resulting resin composition is lowered. For the purpose of improving this and further improving conductivity, a polyamide resin composition in which a specific amount of polyvinyl alcohol resin is blended with a polyamide resin composition blended with discontinuous conductive fibers has been proposed (for example, (See Patent Document 5).

JP-A-9-124923 Japanese Patent Laying-Open No. 2005-264083 JP 2005-145995 A JP 2003-64254 A JP 2002-338802 A

  However, the resin compositions described in Patent Documents 1 and 2 have excellent coating adhesion, but because they contain a large amount of PPE resin or ABS resin that has a lower flow than the polyamide resin, the fibrous material is still used. The blended material had a problem that the appearance (surface property) was remarkably lowered.

  Moreover, although the resin composition described in Patent Document 3 is excellent in the resin property balance, since carbon black is used as the conductive material, there is a limit to the level of conductivity obtained. Furthermore, the resin composition described in Patent Document 4 is also excellent in the balance of resin properties such as fluidity, conductivity, and coating adhesion, but the effect becomes remarkable when the content of the conductive material is small. None of these were satisfactory for the demand for higher conductivity.

  And in patent document 5, although the polyvinyl alcohol resin is mix | blended in order to further improve the electroconductivity of the polyamide resin composition which mix | blended discontinuous conductive fiber, it is the objective of the improvement of electroconductivity, and resin molding There was no suggestion about improving the surface properties of the body and the adhesion of the coating film. Further, those exemplified as polyvinyl alcohol resins are all homopolyvinyl alcohol resins and water-soluble resins mixed therewith, and are essentially themselves (such as kneading extrusion processing and injection molding processing). There was a problem of being a resin lacking suitability for hot melt processing.

  And when the present inventors examined use of the homopolyvinyl alcohol resin as described in Patent Document 5 for a resin molded body for coating, a large amount of gel was generated, and silver (silver) was formed on the surface of the molded body. The problem of remarkably deteriorating the appearance occurred.

In this way, the content of the conductive fiber is still increased and sufficient electrical conductivity, specifically, high electrical conductivity with a surface resistivity of 9 × 10 ⁸ Ω or less is maintained, and the surface property is excellent. And the polyamide resin composition which is excellent also in the coating adhesiveness without requiring a primer treatment etc. has not been found, and its provision has been eagerly desired.

  In view of the above-mentioned problems, the present inventors have made extensive studies on coating resin moldings, particularly coating polyamide resin moldings. As a result, conductive fibers and specific vinyl alcohol have been added to specific polyamide resins having specific physical properties. The present inventors have found that the above problems can be solved by including a copolymer, specifically, an ethylene / vinyl alcohol copolymer and / or a partially saponified product of an ethylene / vinyl acetate copolymer, and completed the present invention. .

  That is, the gist of the present invention resides in a resin molded article for coating formed by molding a resin composition comprising the following components (A) to (C).

  Component (A) At least one polyamide resin selected from the group consisting of polyamide 6 resin, polyamide 66 resin, or a mixture or copolymer thereof having an ISO viscosity of 80 ml / g or more and 160 ml / g or less: 55% by weight or more Less than 88% by weight

  Component (B) Conductive fiber: 11 to 35% by weight.

  Component (C) Partially saponified ethylene / vinyl alcohol copolymer and / or ethylene / vinyl acetate copolymer: 0.1 to 10% by weight.

  The polyamide resin composition according to the present invention and a molded product comprising the polyamide resin composition are suitable as a resin molded product for coating because they are excellent in coating adhesion, do not require a primer, and have an excellent appearance. Moreover, the polyamide resin composition of the present invention and the resin molded body for coating formed by molding the same can adjust the type, blending amount, and dispersion state of the conductive fibers, and exhibit high degree and arbitrary surface resistivity. You can make it. And since it becomes possible to give arbitrary performances, such as electrostatic coating and electromagnetic wave shielding, industrial utility value is very large.

  The resin molded body for coating formed by molding the polyamide resin composition of the present invention is excellent in electrical conductivity, coating film adhesion, appearance, and mechanical properties, so electromagnetic wave shielding, products for electrostatic coating, etc. It can be applied to electrical and electronic parts (for example, protective cases for electronic circuits, various panels, various bases), automotive parts (for example, fenders, garnishes, exterior panels, doors, housings for various sensors, etc.), machinery It is expected that the effect becomes remarkable by applying to parts.

  Hereinafter, the present invention will be described in detail.

Component (A) Polyamide Resin Component (A) used in the present invention is at least one selected from the group consisting of polyamide 6 resin, polyamide 66 resin, or a mixture or copolymer thereof having an ISO viscosity of 80 to 160. Polyamide resin. More specifically, a polyamide 6 resin (hereinafter sometimes referred to as “PA6”), a polyamide 66 resin (hereinafter sometimes referred to as “PA66”), a co-weight of the polyamide 6 resin and the polyamide 66 resin. It shows at least one polyamide resin selected from the group consisting of a coalescence and this mixture (blend).

  As the component (A) used in the present invention, polyamide 6 resin or a mixture or copolymer of polyamide 6 resin and 66 resin rich in polyamide 6 resin and the 66 resin (hereinafter referred to as “PA6 / PA66”) may be used. )), The impact resistance tends to be improved. Further, by using polyamide 66 resin or a mixture or copolymer of polyamide 66 resin and 66 resin (hereinafter sometimes referred to as “PA66 / PA6”) rich in polyamide 66 resin, PA66 / PA6 is particularly used. When it is a blend, the heat-resistant rigidity tends to be improved.

  In the present invention, by using a specific polyamide resin such as PA6 or PA66 as the component (A), the coating resin molded body has physical properties such as coating adhesion, appearance, thermal stability, mechanical properties, It tends to improve in a well-balanced manner. The component (A) used in the present invention may be determined by appropriately selecting a polyamide resin within the scope of the present invention according to its use.

  In particular, PA66 and PA66 / PA6, which have little dimensional change due to the influence of rainfall and humidity, are preferable for applications exposed to outdoor environments. Further, PA6 and PA6 / PA66, which are excellent in impact resistance, are preferable for portable electronic device housing applications. Furthermore, PA66 and PA66 / PA6, which are excellent in heat resistance, are preferable when the product coating process and usage environment exceed 210 ° C, and moderate heat resistance when used at a temperature of 210 ° C or lower. PA6 and PA6 / PA66 are preferable because they have excellent moldability.

  The polyamide resin of component (A) used in the present invention is characterized by having an ISO viscosity of 80 to 160 ml / g. Here, the ISO viscosity number indicates a viscosity number measured under the method defined in ISO-307, specifically, in a 96% concentrated sulfuric acid at a concentration of 0.5% by weight and 23 ° C. By setting the viscosity number to 80 to 160 ml / g, the resin molded body for coating of the present invention can be made excellent in appearance and mechanical properties.

  If the ISO viscosity number is too small, the mechanical properties are deteriorated. Conversely, if the ISO viscosity number is too large, the fluidity and appearance are deteriorated. Therefore, the ISO viscosity number of the component (A) used in the present invention is preferably 95 to 140 ml / g when the component (A) is PA6 resin or PA6 / 66, and is preferably PA66 resin or PA66 / 6 resin. In this case, it is preferably 120 to 155 ml / g.

  The concentration of the terminal amino group and carboxyl group (end group concentration) of the component (A) polyamide resin used in the present invention is arbitrary, and a part of the end group is terminated with acetic acid, stearic acid, stearylamine or the like. It may be sealed or denatured. Especially in this invention, it is preferable that the ratio (carboxyl group / amino group) of the terminal group density | concentration of the polyamide resin of the component (A) used for this invention is 0.3-5 from a heat-stable point.

  Content of the component (A) in the resin molding for coating of the present invention is 55% by weight or more and less than 88% by weight. When there are too few components (A), the external appearance in the resin molding for coating of this invention will become defect, and conversely, even if there are too many, it will not become favorable electroconductivity. Therefore, the component (A) in the present invention is preferably 60% by weight or more and less than 88% by weight, and particularly preferably 70% by weight or more and less than 88% by weight.

Component (B) Conductive Fiber The component (B) conductive fiber used in the present invention may be a conventionally known arbitrary conductive fiber, and usually has a volume resistivity of 1 × 10 ³ Ω · cm or less. Use what has.

  Specific examples of the component (B) used in the present invention include metal fibers such as nickel, copper and SUS; carbon fibers; organic or inorganic fibers coated with metals such as tin, copper and nickel; It is done. Among these, nickel fiber and carbon fiber are preferable from the viewpoint of excellent balance of conductivity and mechanical properties and easy availability, and carbon fiber has good conductivity and low specific gravity. This is preferable because the resin molded body for coating can be reduced in weight.

  The shape of the conductive fiber of the component (B) used in the present invention may be appropriately selected and determined as long as it is a normal so-called fibrous one. If the fiber length is too short, the impact resistance of the resin molded body for coating of the present invention is lowered. Conversely, if the fiber length is too long, the appearance may be lowered, so the weight average fiber diameter is 0.1 to 100 μm. Of these, 1 to 20 μm is preferable.

  Further, if the weight average fiber length is too short, the electrical conductivity is lowered, and conversely if it is too long, the appearance is lowered. Therefore, the weight average fiber length is preferably 1 μm to 2 cm, and more preferably 20 μm to 1 cm. . Furthermore, it is preferable that the above-mentioned ratio of the weight average fiber length to the weight average fiber diameter (average aspect ratio; weight average fiber length / weight average fiber diameter ratio) is 2 or more.

  As described above, as the component (B) used in the present invention, carbon fiber is preferable, but the production method thereof is arbitrary, and conventionally known production methods such as PAN, pitch, cellulose, and hydrocarbon gases are used. Any of the weight average fiber length / weight average fiber diameter and graphite fiber of the phase growth system may be used. When carbon fiber is used as the component (B) conductive fiber used in the present invention, PAN-based carbon fiber is particularly preferable because of its excellent balance of strength, impact resistance, and conductivity.

  The carbon fiber used in the present invention is obtained by treating a part or all of the surface with an organic substance, or by nickel, ytterbium, gold, silver, plating, CVD, PVD, ion plating, vapor deposition, etc. You may be covered with metal components, such as copper and tin. Among these, in order to improve the handleability and the dispersibility of the component (A) in the resin, it is preferable to use those treated with a sizing agent (bundling agent).

  Any conventionally known sizing agent (sizing agent) can be used. Specifically, epoxy compounds, polyurethane compounds, saturated or unsaturated polyesters, polyphenylene sulfites, polyphenylene ethers, polycarbonates, polyoxymethylenes, polystyrenes, polyolefins, acrylic resins, vinyl acetate resins, ethylene vinyl acetate copolymers, polyamide resins, etc. A homopolymer, a copolymer, etc. are mentioned.

  Of these, epoxy compounds, polyamide compounds, and urethane compounds are preferred. The sizing agent (sizing agent) may be water-soluble or water-insoluble, but among them, a water-soluble one that is easy to sizing is preferable. The content of the sizing agent (bundling agent) in the component (B) may be appropriately selected and determined. However, if the amount is too small, the effect of improving the handleability of the conductive fibers is not sufficient, and conversely too much. Thermal stability and conductivity are reduced. Therefore, the content is preferably 0.5 to 10% by weight, particularly 2 to 8% by weight.

And content of the conductive fiber of a component (B) in the resin molding for coating of this invention is 11 to 35 weight%. When the component (B) is less than 11% by weight, the electrical conductivity becomes insufficient, while when it exceeds 35% by weight, the appearance is deteriorated. In the present invention, the content of the component (B) may be appropriately selected and determined within the above range according to the use of the resin molded body of the present invention. Specifically, for example, when electromagnetic shielding properties are required, the surface resistivity of the resin molded body may be set to 1 × 10 ³ Ω or less. When applying electrostatic coating, it is preferably 1 × 10 ⁸ Ω or less, more preferably 1 × 10 ¹⁰ Ω or less.

Component (C) Ethylene / vinyl alcohol copolymer and / or partially saponified product of ethylene / vinyl acetate copolymer The ethylene / vinyl alcohol copolymer of component (C) used in the present invention is ethylene and vinyl alcohol. Random copolymer. Component (C) used in the present invention usually has an ethylene copolymerization ratio of 1 to 99 mol%. If the ethylene content is too high, the coating adhesion tends to decrease, and conversely if the ethylene content is too low, the thermal stability of the polyamide resin composition for resin moldings for coating of the present invention decreases and the appearance of the molded product May decrease. Therefore, the ethylene content is preferably 20 to 70 mol%, and more preferably 30 to 70 mol%.

  The saponification degree in the partially saponified ethylene / vinyl acetate copolymer of the component (C) used in the present invention may be appropriately selected and determined, but is usually 40 mol% or more. If the degree of saponification is too low, the thermal stability at the time of melting of the polyamide resin composition for a resin molded body for coating of the present invention may be lowered. Therefore, the saponification degree is preferably 60 mol% or more, more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

  The saponified ethylene / vinyl acetate copolymer partially saponified as the component (C) used in the present invention may be determined by appropriately selecting the MI measured according to JIS-K6730. It is 10 minutes, and 0.8 to 250 g / 10 minutes is particularly preferable from the viewpoint of the melt fluidity and strength of the polyamide resin composition for a resin molded body for coating of the present invention.

  In the partially saponified ethylene / vinyl acetate copolymer component (C) used in the present invention, the ethylene / vinyl acetate copolymer contains a small amount of a copolymerizable monomer component. Also good. Examples of the copolymerizable monomer component include α-olefins such as propylene, isobutene, α-octene, α-dodecene, α-octadecene, unsaturated carboxylic acids or salts thereof, partial alkyl esters, complete alkyl esters, Examples include acrylonitrile, acrylamide, anhydrides, unsaturated sulfonic acids or salts thereof.

  As the component (C) used in the present invention, an ethylene / vinyl alcohol resin is preferably used in view of thermal stability and appearance. Content of the component (C) in this invention exists in the range of 0.1-10 weight%. If the content of component (C) is low, the effect of improving coating adhesion is not sufficient. Conversely, if it is too much, the reaction with component (A) polyamide resin becomes remarkable, and the resin molded product for coating of the present invention Since the melt fluidity of the polyamide resin composition for coating is lowered and the appearance of the resin molded product for coating is lowered, the content of the component (C) is 1 to 10% by weight, particularly 6.5 to 10% by weight. It is preferable that

  The component (C) used in the present invention may be a desired product produced by any conventionally known production method, or a commercially available product may be used. Examples of commercially available saponified ethylene / vinyl acetate copolymers include Eval manufactured by Kuraray and Soarnol manufactured by Nippon Gosei Kagaku.

Other components In the resin molded body for coating of the present invention, other additives, specifically, heat stabilizers, ultraviolet absorbers, flame retardants, reinforcing agents, and components, as long as the effects of the present invention are not impaired. A thermoplastic resin other than (A), a conductive material other than component (B), and the like may be contained.

  Examples of the heat stabilizer include copper halide, potassium iodide, pentaerythritol phosphite compound, phosphinate compound, hindered phenol, hydrotalcite and the like. Examples of the ultraviolet absorber include hindered amines. These contents may be appropriately selected and determined, but are usually 2% by weight or less with respect to the polyamide resin composition for a resin molded article for coating of the present invention.

  Examples of the flame retardant include brominated epoxy, brominated polystyrene, brominated acrylic, brominated polyphenylene ether, antimony compound, zinc borate, melamine cyanurate, melamine polyphosphate, phosphazene, and phosphinate metal salt. These contents may be appropriately selected and determined, but are usually 30% by weight or less with respect to the polyamide resin composition for a resin molded body for coating of the present invention.

  Further, as the conductive material other than the component (B), for example, conductive carbon black such as ketjen black, furnace black, acetylene black, carbon nanotube, flake graphite in the range of 0 to 10% by weight in the total composition. Etc. These contents may be appropriately selected and determined, but are usually 10% by weight or less based on the polyamide resin composition for a resin molded body for coating of the present invention.

  Examples of the reinforcing agent include glass fiber, glass flake, wollastonite, talc, kaolin, mica and the like. These contents may be appropriately selected and determined, but are usually 10% by weight or less based on the polyamide resin composition for a resin molded body for coating of the present invention.

  Among these additives, by using copper halide, specifically, copper iodide and / or copper chloride 0.001 to 0.3% by weight, and potassium iodide 0.01 to 1% by weight in combination, It is preferable because heat aging resistance and weather resistance are improved. The resin molding for coating of the present invention containing these is optimal for outdoor use and for use at a high temperature of 80 ° C. or higher.

  Specific examples of the thermoplastic resin other than the component (A) polyamide resin include, for example, polystyrene resin (PS), polyethylene resin (PE), polypropylene resin (PP), acrylic resin (AN), acrylic-styrene resin ( AS), ABS resin, general-purpose plastics such as high impact polystyrene resin (HIPS); polyamide resin (PA) other than component (A), polycarbonate resin (PC), polybutylene terephthalate resin (PBT), polyphenylene ether resin (PPE) Engineering plastics such as liquid crystal polymers (LCP), polyphenylene sulfide resin (PPS), etc .; Super engineering plastics such as acrylic elastomer, styrene elastomer, olefin elastomer, etc. Sexual elastomer resin or the like; and the like.

  The content of these thermoplastic resins may be appropriately selected and determined. Usually, the weight ratio of the thermoplastic resin other than the component (A) and the component (A) (the thermoplastic resin / component other than the component (A)) (A)) is preferably less than 0.8.

  Among thermoplastic resins, the inclusion of a thermoplastic elastomer resin is preferable because impact resistance can be improved. As the thermoplastic elastomer, ethylene / butene copolymer, ethylene / octene copolymer, ethylene / propylene copolymer, styrene / ethylene / butene / styrene copolymer, acrylic / butadiene / styrene copolymer, etc. are particularly preferable. . Further, these thermoplastic elastomer resins are preferably modified with an unsaturated acid or a derivative thereof in order to improve compatibility with the component (A).

  Further, as a thermoplastic resin, a PA resin, specifically, a polyamide 6 copolymer (6I / 6T copolymer) containing terephthalic acid in the monomer unit, a polyamide 6 (MXD6) containing meta-xylene in the monomer unit, etc. Is used, the content is further 0.01 to 0.6 parts by weight, preferably 0.01 to 0.3 parts by weight, based on 1 part by weight of component (A), thereby further improving the appearance. It is preferable because it can be improved.

  As the method for producing the resin molded body for coating of the present invention, any method known in the art for producing a resin composition can be used. Specifically, for example, there is a method of producing a pellet by melting and kneading each component (A), (B), (C) and other additives to be added as necessary, and molding the pellet. . Moreover, the method of shape | molding what dry-blended each component is mentioned. Especially, in this invention, it is preferable to use the method of dry blending the pellet of two or more types of each component. For melt kneading, any conventionally known machine or method can be used. Specifically, for example, a single-screw or twin-screw extruder, a multi-screw extruder, a roll, a Banbury mixer, and the like can be given.

  The production method of the resin molded body for coating of the present invention is not particularly limited, and a molding method generally employed for the resin composition, that is, an injection molding method, a hollow molding method, an extrusion molding method, a sheet molding method, a heat molding method, and the like. What is necessary is just to shape | mold by the shaping | molding method, the rotational molding method, the lamination molding method, the press molding method. Of these, molding by injection molding is preferred because of high cycle characteristics (high productivity).

  As the method for producing the resin molded body for coating of the present invention, among them, resin pellets comprising component (A) and component (B), preferably pellets obtained by melting and kneading components (A) and (B) A method of molding a resin composition obtained by dry blending the component with component (C) is preferred. In addition, when the component (C) is melted and kneaded simultaneously with the components (A) and (B), in order to reduce the thermal stability of the obtained polyamide resin composition and maintain coating adhesion, It is preferable to shorten the residence time of the resin composition in the kneader.

  In addition, a pellet shows the thing of a granule shape here, The shape is arbitrary, Specifically, it is shapes, such as spherical shape, cylindrical shape, and prismatic shape. In addition, the size (dimension) may be appropriately selected and determined from any conventionally known value. However, when the pellet is too small or conversely too large, dispersion stability and biting into the molding machine are reduced. There is. Therefore, the longest diameter is usually 1 to 30 mm, and it is preferable that each of the diameter, the short side, and the long side is a columnar shape or a square column shape having a length of 2 to 5 mm.

  The method for coating the resin molded body for coating of the present invention is not particularly limited, and any conventionally known method for coating a thermoplastic resin molded body can be used. The resin molded body for painting of the present invention is characterized by exhibiting sufficient paint adhesion even without applying a primer treatment that is usually performed when coating with a conventional polyamide resin molded product. A simple primer treatment step can be omitted, but a primer treatment may be performed if necessary. Moreover, since the resin-molded body for painting of the present invention is also excellent in electrical conductivity, an electrostatic coating method implemented on a steel plate for automobile exterior parts can be applied as necessary.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, “%” in the blending amounts in the following examples and comparative examples represents weight%.

  In obtaining each resin composition of Examples and Comparative Examples, the following raw materials were prepared.

1. Ingredient (A)
(A-1) Polyamide 6 resin: manufactured by Mitsubishi Engineering Plastics, Novamid 1010J, viscosity number 118 ml / g, melting point 223 ° C.

(A-2) Polyamide 66 resin: manufactured by DuPont, ZYTEL-FE3218, ISO viscosity number 138 ml / g, melting point 264 ° C.

2. Ingredient (B)
(B-1) Carbon fiber: Toho Tenax Co., Ltd., HTA-C6-N, using a polyamide resin as a sizing agent, sizing agent content 3.5%, average fiber diameter 7 μm, volume resistivity 1.5 × 10 ^-3 Ω · cm

(B-2) Carbon fiber: manufactured by Toho Tenax Co., Ltd., HTA-C6-US, urethane resin is used as a sizing agent, sizing agent content is 2.5%, average fiber diameter is 7 μm, and volume resistivity is 1.5 × 10. ^-3 Ω · cm

3. Ingredient (C)
(C-1) Ethylene / vinyl alcohol resin: Kuraray Co., Ltd., Eval G156A, ethylene copolymerization ratio 47 mol%, saponification degree 99% or more, density 1.12, MI 6 [g / 10 min] (JIS K6730) , Measured under the condition of 190 ° C x 2160g)

(C-2) Partial saponification product of ethylene / vinyl acetate copolymer: manufactured by Tosoh Corporation, Mersen H6960, density 0.99 g / cm 3, melting point 113 ° C., vinyl acetate content 4.2% by weight, saponification degree 90%, MI is 40 [g / 10 min] (measured under the condition of 190 ° C. × 2160 g in accordance with JISK6730)

4). Other ingredients (D)
(D-1) Epoxy resin compound: manufactured by Toto Kasei Co., Ltd., Epototo YD5013
(D-2) Polyvinyl alcohol resin: manufactured by Kuraray Co., Ltd., Poval PVA102, degree of saponification 98-99%
(D-3) Polyamide 6: Mitsubishi Engineering Plastics, 1020J, ISO viscosity number 182 ml / g, melting point 223 ° C.
(D-4) Polyamide 12: manufactured by EMS, Grillamide L20G, melting point 178 ° C.

[Evaluation methods]
(1) Paint adhesion:
A square plate-like molded body having a vertical and horizontal dimension of 100 mm × 100 mm and a thickness of 3 mm was used as a test piece. First, an acrylic / urethane coating (OP-Z-NY, manufactured by Origin Electric Co., Ltd.) was applied to the surface of the test piece and baked at a temperature of 80 ° C. for 60 minutes. Next, 100 square grids each having a width of 1 mm on one side were formed on the painted film surface after baking. A cellophane tape was applied to the surface of the coating film, and when the cellophane tape was peeled off, it was visually observed whether or not the coating film surface was peeled off. The coating film surface was not peeled off with the cellophane tape, and the residual rate of the mass remaining on the surface of the test piece was determined. A sample with a residual rate of 100% was marked with ◯, and other samples were marked with x.

(2) Appearance (2-1) Surface appearance of molded product before painting:
As the test piece, a plate-like molded body before coating was used, similar to that used in the above (1) coating adhesion evaluation.

  The surface appearance of the test piece was visually observed. If a silver streak or a remarkably rough surface was formed, it was rated as x.

(2-2) Paint film surface appearance of molded product after coating In the test piece for which the coating adhesion evaluation of (1) was performed, the coating film of the resin molded product for coating at a portion where no slit was formed The appearance of the surface was visually observed. When a remarkably rough surface is formed, it is marked with ◯ when there is no such defect.

(6) surface resistivity;
The surface resistivity was measured according to JIS-K6911. Advantest Corporation digital super high resistance meter R8340 was used as a measuring device. As the test piece, a plate-like test piece before coating was used in the same manner as that used in the above (1) paint adhesion evaluation.

(3) flexural modulus;
Based on ASTM D790, the bending elastic modulus (unit: MPa) in an absolutely dry state was measured.

(4) Thermal deformation temperature;
Based on ASTM D648, the temperature was measured under a stress condition of 0.45 MPa and in an absolutely dry state.

(5) Impact strength;
In accordance with ASTM D256, an IZOD impact value (unit: J / m) of 1/8 inch thickness was measured in a completely dry state.

(Examples 1-6, Comparative Examples 1-5)
It prepared so that it might become the compounding quantity (weight ratio) of the resin composition shown in Table 1 and 2, and the resin composition was manufactured with the following methods.

  First, using a twin screw extruder (manufactured by Nippon Steel Works, TEX30HCT, screw diameter 30 mmφ), the component (C) is discharged under the conditions of a cylinder temperature of 270 ° C. and a screw rotation speed of 200 rpm, and a discharge rate of 10 kg / h The resin composition pellet which melt-kneaded all the components except was manufactured. At this time, the component (B) was blended from the middle part of the extruder by side feed, and the components (B) other than the component (B) were added all at once from the upstream part of the extruder. Subsequently, the pellets produced by the melt kneading and the component (C) pellets were dry blended with a tumbler mixer and dried with a hot air dryer at 120 ° C. for 8 hours to obtain a polyamide resin composition.

[Preparation of test piece];
Using a molding machine (SH100 manufactured by Sumitomo Heavy Industries, Ltd.), resin temperature 280 ° C., mold temperature 80 ° C., filling time 0.4 sec, pressure holding time 10 sec, cooling time 10 sec, screw rotation speed 150 rpm, back pressure 5 kg / cm ² A test piece was molded and evaluated. The results are shown in Tables 1 and 2.

As is clear from Tables 1 and 2, the polyamide resin compositions (Examples 1 to 6) of the present invention are all excellent in coating adhesion and appearance, and have high conductivity, rigidity and impact resistance. It can be seen that the mechanical properties such as properties and heat-resistant rigidity are excellent in balance of physical properties, showing sufficient characteristic values as a reinforced polyamide resin.

On the other hand, the polyamide resin compositions of Comparative Examples 1 to 8 have problems in any of coating adhesion, appearance, and conductivity, and the balance of various physical properties aimed by the present invention was insufficient. In Comparative Examples 4 to 8, since the appearance defects of the resin molded bodies before and after coating were already remarkable, other evaluations were stopped.

Claims (5)

A resin molded article for coating formed by molding a resin composition comprising the following components (A) to (C).
Component (A) At least one polyamide resin selected from the group consisting of polyamide 6 resin, polyamide 66 resin, or a mixture or copolymer thereof having an ISO viscosity of 80 ml / g or more and 160 ml / g or less: 55% by weight or more Less than 88 wt% component (B) Conductive fiber: 11 to 35 wt%
Component (C) Ethylene / vinyl alcohol copolymer and / or partially saponified ethylene / vinyl acetate copolymer: 0.1 to 10% by weight   2. The resin molding for coating according to claim 1, wherein the component (C) is an ethylene / vinyl alcohol copolymer having a saponification degree of 99% or more.   The resin molded article for coating according to claim 1 or 2, wherein the component (B) is carbon fiber.   The resin molding for coating according to any one of claims 1 to 3, which is obtained by molding a resin composition obtained by dry blending resin pellets comprising component (A) and component (B) and component (C). body. Content of a component (C) is 6.5 to 10 weight%, The resin molding for coating in any one of the Claims 1 thru | or 4 characterized by the above-mentioned.