JP4413707B2 - Heat-dissipating resin molded product with multilayer structure - Google Patents

Description

  The present invention relates to a heat-dissipating resin molded article having no pinhole and excellent gas barrier properties.

  Super engineering plastics such as polyarylene sulfide (hereinafter sometimes abbreviated as PAS) resin and liquid crystalline polymer represented by polyphenylene sulfide (hereinafter abbreviated as PPS) resin have high heat resistance, mechanical properties and chemical resistance. Since it has chemical properties, dimensional stability, and flame retardancy, it is widely used in electrical and electronic equipment component materials, automotive equipment component materials, chemical equipment component materials, and the like. In recent years, these parts have become lighter, thinner, and smaller, and heat radiation inside the parts has become a problem, and there is a demand for a material imparting heat radiation.

  For this reason, as described in Patent Documents 1 and 2, it has been attempted to impart high heat dissipation by adding a conductive filler, but in this method, the molded product exhibits conductivity. Therefore, there are problems that it cannot be used for parts for insulation, problems such as increase in viscosity and brittleness, and problems such as pinholes occurring when the thickness is reduced.

In addition, as described in Patent Documents 3 to 5, attempts have been made to impart heat dissipation and insulation properties by adding an insulating filler. Similar to the method, there were problems such as increased viscosity and brittleness, and pinholes when thinned.
JP-A-2-163137 JP 2003-411119 A JP-A-4-33958 Japanese Patent Laid-Open No. 4-198265 JP 2001-151905 A

  An object of the present invention is to solve such problems of the prior art and to provide a molded article having no pinhole and high thermal conductivity.

  The inventors of the present invention achieved the above-mentioned object, and as a result of intensive search and examination to obtain a molded product having no pinhole and high thermal conductivity, the moldability is inferior, and it is difficult to uniformly reduce the thickness. Pinhole while maintaining high heat dissipation by multilayer extrusion molding of heat-dissipating resin composition with thermal conductivity and resin material with low thermal conductivity that is insulating and excellent in moldability and easy to thin. The inventors have found that an insulating heat-dissipating resin molded product having no surface can be obtained, and have completed the present invention.

That is, the present invention provides a heat-dissipating resin composition (A) having a thermal conductivity of 1 W / m · K or more, a thermal conductivity of 0.5 W / m · K or less, and a volume resistivity of 1 × 10 ¹⁰ Ω. · A molded product obtained by multilayer extrusion molding of a resin material (B) that is greater than or equal to cm, and the thickness of one layer of the resin material (B) is 0.01 to 0.1 mm. Is a heat-dissipating resin molded product exhibiting an adhesion strength greater than 2.

  According to the present invention, using a material having high thermal conductivity, it becomes easy to form a heat sink without pinholes.

Hereinafter, the present invention will be described in detail. The heat-dissipating resin composition (A) having a thermal conductivity of 1 W / m · K or more used in the present invention and a thermal conductivity of 0.5 W / m · K or less and a volume resistivity of 1 × 10 ¹⁰ Ω · cm As the resin used for the resin material (B), any resin can be used as long as it is a resin that can be subjected to multilayer extrusion molding. However, engineering plastics are preferable and more preferable in terms of heat resistance and chemical resistance. Is a thermoplastic resin belonging to super engineering plastics. Among these, PAS resin and liquid crystalline polymer excellent in moldability are preferable.

  The PAS resin used in the present invention is mainly composed of — (Ar—S) — (wherein Ar is an arylene group) as a repeating unit. Examples of the arylene group include p-phenylene group, m-phenylene group, o-phenylene group, substituted phenylene group, p, p′-diphenylene sulfone group, p, p′-biphenylene group, and p, p′-di. A phenylene ether group, p, p′-diphenylenecarbonyl group, naphthalene group, and the like can be used. In this case, among the arylene sulfide groups composed of the above-mentioned arylene groups, in addition to a polymer using the same repeating unit, that is, a homopolymer, a copolymer containing different repeating units from the viewpoint of processability of the composition May be preferred. As the homopolymer, those having a p-phenylene sulfide group as a repeating unit and using a p-phenylene group as an arylene group are particularly preferably used. In addition, as the copolymer, among the arylene sulfide groups comprising the above-mentioned arylene groups, two or more different combinations can be used, and among them, a combination containing a p-phenylene sulfide group and an m-phenylene sulfide group is particularly preferably used. It is done. Among these, those containing 70 mol% or more, preferably 80 mol% or more of p-phenylene sulfide groups are suitable from the viewpoint of physical properties such as heat resistance, fluidity (moldability) and mechanical properties.

Further, among these PAS resins, a high molecular weight polymer having a substantially linear structure obtained by condensation polymerization from a monomer mainly composed of a bifunctional halogen aromatic compound can be particularly preferably used. In addition to the PAS resin having a structure, a polymer in which a branched structure or a crosslinked structure is partially formed by using a small amount of a monomer such as a polyhaloaromatic compound having three or more halogen substituents when polycondensation is performed. It is also possible to use a polymer in which a low molecular weight linear structure polymer is heated at a high temperature in the presence of oxygen or an oxidant to increase the melt viscosity by oxidative crosslinking or thermal crosslinking to improve the moldability. The PAS resin is mainly composed of the linear PAS (the viscosity at 310 ° C. and the shear rate of 1200 sec ⁻¹ is 10 to 300 Pa · s), and a part thereof (1 to 30% by weight, preferably 2 to 25% by weight). ) May be a mixed system with a branched or crosslinked PAS resin having a relatively high viscosity (300 to 3000 Pa · s, preferably 500 to 2000 Pa · s).

  In addition, the PAS resin used in the present invention is preferably a PAS resin that has been subjected to acid cleaning, hot water cleaning, organic solvent cleaning (or a combination thereof) and the like after polymerization to remove by-product impurities.

  Next, the liquid crystalline polymer used in the present invention refers to a melt processable polymer having a property capable of forming an optically anisotropic molten phase. The property of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the anisotropic molten phase can be confirmed by using a Leitz polarizing microscope and observing a molten sample placed on a Leitz hot stage under a nitrogen atmosphere at a magnification of 40 times. When the liquid crystalline polymer applicable to the present invention is inspected between crossed polarizers, the polarized light is normally transmitted even in the molten stationary state, and optically anisotropic.

  The liquid crystalline polymer as described above is not particularly limited, but is preferably an aromatic polyester or an aromatic polyester amide, and a polyester partially containing an aromatic polyester or an aromatic polyester amide in the same molecular chain. It is in. They preferably have a logarithmic viscosity (IV) of at least about 2.0 dl / g, more preferably 2.0-10.0 dl / g when dissolved in pentafluorophenol at 60 ° C. at a concentration of 0.1% by weight. .) Are used.

  The aromatic polyester or aromatic polyester amide as the liquid crystalline polymer applicable to the present invention is particularly preferably at least one compound selected from the group of aromatic hydroxycarboxylic acids, aromatic hydroxyamines, and aromatic diamines. Aromatic polyesters and aromatic polyester amides as constituent components.

More specifically,
(1) A polyester mainly composed of one or more aromatic hydroxycarboxylic acids and derivatives thereof;
(2) mainly (a) one or more of aromatic hydroxycarboxylic acids and derivatives thereof; and (b) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof; c) Polyester comprising at least one or more of aromatic diol, alicyclic diol, aliphatic diol and derivatives thereof;
(3) mainly (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof; and (c). A polyesteramide comprising one or more of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof;
(4) mainly (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof; and (c). One or more of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof; and (d) at least one or more of aromatic diol, alicyclic diol, aliphatic diol and derivatives thereof, and The polyesteramide which consists of, etc. are mentioned. Furthermore, you may use a molecular weight modifier together with said structural component as needed.

  Preferable examples of specific compounds constituting the liquid crystalline polymer applicable to the present invention include p-hydroxybenzoic acid, aromatic hydroxycarboxylic acids such as 6-hydroxy-2-naphthoic acid, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl, hydroquinone, resorcin, aromatic diols such as compounds represented by the following general formula (I) and the following general formula (II); terephthalic acid, isophthalic acid, 4 , 4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and aromatic dicarboxylic acids such as compounds represented by the following general formula (III); aromatic amines such as p-aminophenol and p-phenylenediamine Can be mentioned.

(However, X: alkylene (C1 -C4), alkylidene, -O-, -SO -, - SO 2 -, -S -, - CO- than group _{selected, Y :-( CH 2) n -} (n = 1~4), - O (CH 2) n O- (n = 1~4) from the group selected)
Particularly preferred liquid crystalline polymers to which the present invention is applied are aromatic polyesters containing p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid as main structural unit components.

  Next, the heat-dissipating resin composition (A) having a thermal conductivity of 1 W / m · K or more used in the present invention is obtained by adding a filler having a high thermal conductivity to a resin capable of multilayer extrusion molding. In particular, it is preferable to add a filler having high thermal conductivity to the PAS resin or liquid crystalline polymer. As the filler having a high thermal conductivity used here, any filler can be used as long as it has a thermal conductivity of 2 W / m · K or more. However, alumina, Boron nitride, magnesia and graphite are preferred. These fillers can be used alone or in combination of two or more. Moreover, when using these fillers, if necessary, they can be converged or surface-treated with a sizing agent or a surface treatment agent.

  The amount of filler added is not particularly limited as long as the heat conductivity of the heat dissipating resin composition (A) is 1 W / m · K or more, but generally the heat dissipating resin composition (A) The content is preferably 30% by weight or more, more preferably 50% by weight or more.

  In addition, the heat-dissipating resin composition (A) is blended with inorganic or organic fillers other than the above high thermal conductive fillers in order to improve performance such as mechanical strength, heat resistance and dimensional stability (deformation resistance, warpage). Alternatively, a fibrous, powdery, or plate-like filler may be used depending on the purpose.

  Examples of the fibrous filler include inorganic fibrous materials such as glass fiber, asbestos fiber, boron fiber, and potassium titanate fiber. A particularly typical fibrous filler is glass fiber. High melting point organic fiber materials such as polyamide, fluororesin and acrylic resin can also be used.

  The granular fillers include quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, wollastonite, silicate, iron oxide, titanium oxide, zinc oxide, etc. Examples include metal oxides, metal carbonates such as calcium carbonate and magnesium carbonate, and metal sulfates such as calcium sulfate and barium sulfate.

  Examples of the plate-like filler include mica and glass flakes.

  Furthermore, known substances generally added to thermoplastic resins, that is, flame retardants, colorants such as dyes and pigments, stabilizers such as antioxidants and ultraviolet absorbers, lubricants, crystallization accelerators, crystal nucleating agents, etc. In addition, compositions appropriately added according to the required performance can also be used in the present invention.

On the other hand, as the resin material (B) used in the present invention, any resin material can be used as long as the thermal conductivity is 0.5 W / m · K or less and the volume resistivity is 1 × 10 ¹⁰ Ω · cm or more. However, a resin material using the same resin as that used in the heat-dissipating resin composition (A) is preferable from the viewpoint of weldability at the time of multilayer extrusion molding.

As long as the resin material (B) satisfies the conditions of a thermal conductivity of 0.5 W / m · K or less and a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more, the resin can be used alone, and a filler is added. It may be a resin composition. As the filler added to the resin material (B), any filler can be added as long as the thermal conductivity of the composition is 0.5 W / m · K or less and the volume resistivity is 1 × 10 ¹⁰ Ω · cm or more. However, the filler addition amount is preferably 50% by weight or less, more preferably 30% by weight or less in the resin material (B) from the viewpoint of maintaining the moldability during multilayer extrusion molding and suppressing the generation of pinholes. .

  The multilayer molded article of the present invention is molded by a multilayer extrusion molding method. As the multilayer extrusion molding method, any known method such as multilayer T-die film / sheet molding, multilayer inflation film molding, multilayer pipe / tube extrusion molding, multilayer profile extrusion molding, or the like may be used. In addition, an adhesive layer can be used for bonding the layers.

  Further, the thickness of the resin material (B) is important, and if it is too thin, pinholes are frequently generated and reliability is lowered, which is not preferable. On the other hand, if it is too thick, the heat conductivity of the heat-dissipating resin molded product is lowered, which is not preferable. Therefore, the thickness of one layer of the resin material (B) needs to be 0.01 to 0.1 mm, and more preferably 0.02 to 0.06 mm. Here, the thickness of one layer of the resin material (B) means not the total layer thickness but the thickness of each layer when two or more layers of the resin material (B) are used. To do.

  Moreover, it is important from a practical point of view that the multilayer molded article of the present invention exhibits an adhesive strength with an evaluation score of resin delamination by the X-cut tape method to be described later of greater than 2.

  Furthermore, the ratio of the layer thickness of the heat-dissipating resin composition (A) to the total thickness of the multilayer molded product is also important, and if it is too small, the reliability due to frequent pinholes in the heat-dissipating resin composition (A) layer. This is not preferable because of lowering of heat resistance and thermal conductivity as a multilayer molded article. On the other hand, if the amount is too large, pinholes are generated in the resin material (B) and the reliability is lowered. Therefore, the layer thickness of the heat dissipating resin composition (A) with respect to the entire thickness of the multilayer molded article needs to be 55 to 98%, and more preferably 60 to 95%.

Next, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these. In addition, the method of the physical property measurement in an Example is as follows.
(1) Interlayer adhesion evaluation In accordance with the JIS K5400 X-cut tape method, a multilayer molded product was extruded into a sheet shape, cut to the interlayer, and scored according to the degree of peeling from the interlayer.
(2) Pinhole evaluation The multilayer sheet was cut into a size of 10 cm square and set in a differential pressure type gas permeability measuring device manufactured by Toyo Seiki Seisakusho. The pressure on both sides of the sheet was set to 1 atmosphere of oxygen and 0 atmosphere, respectively, and the presence or absence of pinholes was evaluated from the change in pressure of the cell set to 0 atmosphere after being left for 30 minutes. If the pressure change of the cell was 5 mmHg or less, it was judged that there was no pinhole, and it was judged that the homogeneity was good.
(3) Thermal conductivity The center of the molded sheet was punched into a 1 cm diameter circle, and the thermal diffusivity was measured using a Rigaku laser flash measuring machine LF / TCM-FA8510B. The specific heat and specific gravity of each resin material used were calculated based on the thickness structure of the multilayer sheet, and the thermal conductivity of the multilayer sheet was determined using the formula of thermal diffusivity x specific heat x specific gravity.
Examples 1-6, Comparative Examples 1-7
Using the resin material described below, a T-die multilayer sheet having a width of 10 cm and a thickness of 0.3 mm was extruded using a plast mill (3-layer T die) manufactured by Toyo Seiki Seisakusho. Table 1 shows the material configuration and thickness of the multilayer sheet of the example, and Table 2 shows the material configuration and thickness of the (multilayer) sheet of the comparative example. Table 3 shows the evaluation results of each sheet.
(Materials used)
Heat dissipation resin composition (A)
-(A-1) 60% by weight (in the composition) of graphite (thermal conductivity 100-150 W / m · K) blended with PPS resin (B-1) below; thermal conductivity 5.8 W / m K
-(A-2) 70% by weight (in the composition) of magnesia (thermal conductivity 30-40 W / m · K) blended with PPS resin (B-1) below; thermal conductivity 1.5 W / m K
・ (A-3) LCP of the following (B-2) blended with 60% by weight of alumina (thermal conductivity 20-30 W / m · K) (in composition); thermal conductivity 2.3 W / m · K
・ (A-4) LCP of the following (B-2), 40% by weight (in composition) of boron nitride (thermal conductivity 50 to 60 W / m · K); thermal conductivity 1.8 W / m K
-(A-5) 40% by weight (in the composition) of glass fiber (thermal conductivity 0.6-0.8 W / m · K) blended with PPS resin (B-1) below; thermal conductivity 0.5 W / m ・ K (comparative product)
Resin material (B)
(B-1) Polyphenylene sulfide (PPS) resin: manufactured by Polyplastics Co., Ltd., Fortron 0220A9; thermal conductivity 0.2 W / m · K, volume resistivity 2 × 10 ¹⁶ Ω · cm
(B-2) Liquid crystalline polymer (LCP): Polyplastics Co., Ltd., Vectra A950; thermal conductivity 0.3 W / m · K, volume resistivity 6 × 10 ¹⁶ Ω · cm

Claims (2)

A heat-dissipating resin composition (Ai) having a thermal conductivity of 1 W / m · K or more, comprising a polyarylene sulfide resin blended with one or more fillers selected from alumina, boron nitride, magnesia and graphite; A polyarylene sulfide resin material (Bi) having a thermal conductivity of 0.5 W / m · K or less and a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more, which is a molded product obtained by multilayer extrusion molding, A heat-dissipating resin molded product in which the thickness of one layer of Bi) is 0.01 to 0.1 mm and the evaluation score of resin delamination by the X-cut tape method is greater than 2. A heat-dissipating resin composition having a thermal conductivity of 1 W / m · K or more, comprising a liquid crystalline polymer comprising an aromatic polyester and one or more fillers selected from alumina, boron nitride, magnesia and graphite ( A-ii) and a liquid crystalline polymer resin material (B-ii) comprising an aromatic polyester having a thermal conductivity of 0.5 W / m · K or less and a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more. This is a multilayer extrusion molded product, the thickness of one layer of the resin material (B-ii) is 0.01 to 0.1 mm, and the adhesion score of the resin delamination by the X-cut tape method is greater than 2. Heat-dissipating resin molded product.