JP2019016594A - Polybutylene terephthalate resin composition for sealing member - Google Patents

Abstract

To provide a polybutylene terephthalate resin composition for a seal member which is excellent in sealing property, heat resistance, and toughness, is less likely to generate burr and is suitable for a material for a seal member.SOLUTION: The polybutylene terephthalate resin composition for a seal member includes: 0.5 to 20 pts.mass of an inorganic filler, having an aspect ratio of 3 to 200 and an average particle diameter of 5 to 300 μm; and 0.1 to 20 pts.mass of an olefin resin and/or fluorine resin on the basis of 100 pts.mass of the polybutylene terephthalate resin.SELECTED DRAWING: None

Description

  The present invention relates to a polybutylene terephthalate resin composition suitably used as a sealing member such as a gasket.

  A sealed battery such as a coin-type battery or a button-type battery includes a metal case and a lid as outer members, and a battery material such as an electrolyte sealed in the case is sealed by covering the lid. And in order to prevent the electrolyte etc. in a case from leaking outside, a sealing member such as a gasket formed by molding a resin material is provided at a portion where the case and the lid are in contact with each other, and is reliably sealed. That is, the sealing performance is first mentioned as the required performance of the gasket. Therefore, various conventional gasket materials for satisfying sealing properties have been proposed (see, for example, Patent Documents 1 and 2).

  In addition, for example, when the battery as described above is used for automobile parts, the gasket is also required to have heat resistance. On the other hand, in the example of the battery as described above, the gasket is provided between the case and the lid, and is used in a crimped state. Therefore, a certain degree of toughness is also required to prevent damage when the gasket is caulked. In addition, if there is a gap between the case and the lid, there is a concern that the electrolyte or the like leaks from the gap. One cause of such a gap is that a burr is generated when the gasket is molded, and the burr is sandwiched between the case and the lid. In particular, as described above, since the gasket is used by being clamped between the case and the lid, the molded product is usually thin to some extent. In order to mold such a thin molded product, it is necessary to use a material with high fluidity. However, the high fluidity of the material means that it is easy to enter the gap between molds and to generate burrs. Tend to be. For this reason, the material for molding the gasket is also required to be a material that hardly generates burrs. It is not easy to satisfy all of these required performances.

  On the other hand, polybutylene terephthalate resin (hereinafter also referred to as “PBT resin”) has high heat resistance and is excellent in electrical properties, mechanical properties, weather resistance, chemical resistance, etc. It is widely used for various applications such as automobile parts. Therefore, the composition containing the PBT resin is useful as a material for the gasket as described above, but it is excellent in various performances as described above, that is, sealing properties, heat resistance, and toughness, and it is difficult to generate burrs. It is not straightforward, and it requires careful ingenuity.

Japanese Patent No. 5720125 Japanese Patent No. 5809788

  The present invention has been made in view of the above-described conventional problems, and its problems are excellent in sealing properties, heat resistance, and toughness, hardly generate burrs, and suitable for use as a sealing member material. The object is to provide a terephthalate resin composition.

One aspect of the present invention that solves the above problems is as follows.
(1) 0.5 to 20 parts by mass of an inorganic filler having an aspect ratio of 3 to 200 and an average particle size of 5 to 300 μm, 100 parts by mass of the polybutylene terephthalate resin, an olefin resin and / or Or the polybutylene terephthalate resin composition for sealing members containing 0.1-20 mass parts of fluororesins.

(2) The polybutylene terephthalate resin composition for seal members according to (1), wherein the seal member is a gasket.

(3) The polybutylene terephthalate resin composition for a seal member according to (2), wherein the gasket is for vehicle use.

(4) The polybutylene terephthalate resin composition for sealing members according to (2), wherein the gasket is for a lithium battery.

(5) The polybutylene terephthalate resin composition for sealing members according to (4), wherein the lithium battery is a coin type or a button type.

(6) The polybutylene terephthalate resin composition for seal members according to (4) or (5), wherein the lithium battery is a primary battery.

  According to the present invention, it is possible to provide a polybutylene terephthalate resin composition for a seal member that is excellent in sealing properties, heat resistance, and toughness, hardly generates burrs, and is suitable as a material for a seal member.

The polybutylene terephthalate resin composition for a seal member of the present embodiment is an inorganic filler 1 having an aspect ratio of 5 to 100 and an average particle diameter of 5 to 300 μm with respect to 100 parts by mass of the polybutylene terephthalate resin. It contains 20 parts by mass and 0.1 to 20 parts by mass of an olefin resin and / or a fluorine resin. Hereinafter, the polybutylene terephthalate resin is also referred to as “PBT resin” and the “polybutylene terephthalate resin composition for seal members” is also simply referred to as “PBT resin composition”.
The PBT resin composition of the present embodiment is a resin composition that is excellent in sealing properties, heat resistance, and toughness, hardly generates burrs, and is suitable as a material for a sealing member. First, each component in the PBT resin composition will be described below.

[PBT resin]
The PBT resin includes a dicarboxylic acid component containing at least terephthalic acid or an ester-forming derivative thereof (C1-6 alkyl ester, acid halide, etc.) and an alkylene glycol (1,4-butanediol) having at least 4 carbon atoms or It is a resin obtained by polycondensation with a glycol component containing an ester-forming derivative (acetylated product or the like). The PBT resin is not limited to homopolybutylene terephthalate but may be a copolymer containing 60 mol% or more (particularly 75 mol% or more and 95 mol% or less) of a butylene terephthalate unit.

  The amount of the terminal carboxyl group of the PBT resin is not particularly limited as long as the effect of the present invention is not inhibited. The amount of terminal carboxyl groups of the PBT resin is preferably 30 meq / kg or less, and more preferably 25 meq / kg or less.

The intrinsic viscosity (IV) of the PBT resin is 0.60 to 1.00 dL / g, preferably 0.70 to 0.95 dL / g, and more preferably 0.75 to 0.90 dL / g. When a PBT resin having an intrinsic viscosity in such a range is used, the resulting PBT resin composition is particularly excellent in fluidity. Conversely, if the intrinsic viscosity is less than 0.60 dL / g, the mechanical properties may be insufficient, and if it exceeds 1.00 dL / g, excellent fluidity cannot be obtained.
The PBT resin having an intrinsic viscosity in the above range can be adjusted by blending PBT resins having different intrinsic viscosities. For example, a PBT resin having an intrinsic viscosity of 0.8 dL / g can be prepared by blending a PBT resin having an intrinsic viscosity of 0.9 dL / g and a PBT resin having an intrinsic viscosity of 0.7 dL / g. The intrinsic viscosity (IV) of the PBT resin can be measured, for example, in o-chlorophenol at a temperature of 35 ° C.

  In the PBT resin, as dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives, for example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-dicarboxydiphenyl ether, etc. C8-14 aromatic dicarboxylic acids; C4-16 alkane dicarboxylic acids such as succinic acid, adipic acid, azelaic acid and sebacic acid; C5-10 cycloalkane dicarboxylic acids such as cyclohexane dicarboxylic acid; of these dicarboxylic acid components And ester-forming derivatives (C1-6 alkyl ester derivatives, acid halides, etc.). These dicarboxylic acid components can be used alone or in combination of two or more.

  Among these dicarboxylic acid components, C8-12 aromatic dicarboxylic acids such as isophthalic acid, and C6-12 alkanedicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid are more preferable.

  In the PBT resin, as glycol components (comonomer components) other than 1,4-butanediol, for example, ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, 1, C2-10 alkylene glycol such as 3-octanediol; polyoxyalkylene glycol such as diethylene glycol, triethylene glycol and dipropylene glycol; alicyclic diol such as cyclohexanedimethanol and hydrogenated bisphenol A; bisphenol A, 4,4 Bisphenols, such as aromatic diols such as' -dihydroxybiphenyl; ethylene oxide 2 mol adducts of bisphenol A, propylene oxide 3 mol adducts of bisphenol A, etc. Alkylene oxide adducts of C2-4 of A; or ester-forming derivatives of these glycols (acetylated, etc.). These glycol components can be used alone or in combination of two or more.

  Among these glycol components, C2-6 alkylene glycol such as ethylene glycol and trimethylene glycol, polyoxyalkylene glycol such as diethylene glycol, and alicyclic diol such as cyclohexanedimethanol are more preferable.

  Examples of comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-carboxy-4′-hydroxybiphenyl. Aromatic hydroxycarboxylic acids; Aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; C3-12 lactones such as propiolactone, butyrolactone, valerolactone, caprolactone (ε-caprolactone, etc.); ester formation of these comonomer components Derivatives (C1-6 alkyl ester derivatives, acid halides, acetylates, etc.).

[Inorganic filler]
The inorganic filler used in the PBT resin composition of the present embodiment is an inorganic filler having an aspect ratio of 3 to 200 and an average particle diameter of 5 to 300 μm.

  By setting the aspect ratio of the inorganic filler to 3 to 200, it is possible to secure the caulking property by improving the sealing property by the orientation at the time of injection molding and not impairing the toughness of the PBT resin composition. When the aspect ratio is less than 3, the sealing property becomes insufficient, and when it exceeds 200, the caulking property becomes insufficient. The aspect ratio is preferably 5 to 150, and more preferably 5.5 to 100. In this specification, the aspect ratio is used as an index representing the anisotropy of a shape such as a fiber shape or a plate shape, and is a ratio of the maximum length to the maximum vertical length (aspect ratio = maximum length / maximum vertical). Long). For example, in the case of a fibrous filler, the aspect ratio is the ratio between the length in the major axis direction and the maximum value in the direction perpendicular to the major axis.

  When the average particle diameter of the inorganic filler is 5 to 300 μm, both sealing properties and caulking properties can be achieved. When the average particle size is less than 5 μm, the caulking property becomes insufficient, and when it exceeds 300 μm, the sealing property becomes insufficient particularly in a thin molded product. The average particle size is preferably 10 to 200 μm, and more preferably 12 to 100 μm. In the present specification, the average particle size means a particle size having an integrated value of 50% in a particle size distribution measured by a laser diffraction / scattering method for an inorganic filler before being melt-kneaded as a resin composition. In addition, when the inorganic filler is not in the form of particles, plates or powders but in a fibrous form, the average fiber length or the average fiber diameter, whichever is larger, is regarded as the average particle diameter.

  Examples of the material for the inorganic filler include talc, mica, glass flakes, boron nitride, and the like. Among these, talc and mica are preferable.

  In the PBT resin composition of the present embodiment, the inorganic filler is included in an amount of 0.5 to 20 parts by mass with respect to 100 parts by mass of the PBT resin. If it exceeds 1, the fluidity will be lowered, and it will be difficult to form a thin gasket or the like. The content is preferably 2 to 10 parts by mass.

  The PBT resin composition of this embodiment contains an olefin resin and / or a fluorine resin. Hereinafter, each resin will be described.

[Olefin resin]
Examples of the olefin resin include polyethylene, polypropylene, and cyclic polyolefin. Among these, polyethylene and polypropylene are preferable.

[Fluorine resin]
Examples of the fluororesin include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, and an ethylene / chlorotrifluoroethylene copolymer. Among them, polytetrafluoroethylene is preferable.
The polytetrafluoroethylene used in this embodiment is not only a tetrafluoroethylene polymer, but also a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-perfluoroalkoxyethylene copolymer. , Ethylene trifluoride copolymer, tetrafluoroethylene-ethylene copolymer and the like are also included.

The olefin-based resin and / or fluorine-based resin includes 0.1 to 20 parts by mass with respect to 100 parts by mass of the PBT resin. It is disadvantageous in terms of caulking and burr. The content is preferably 0.5 to 10 parts by mass, and more preferably 1 to 8 parts by mass.
When the olefin resin and the fluorine resin are used in combination, the content ratio (X / Y) of the olefin resin (X) and the fluorine resin (Y) is preferably 1/10 to 10/1. . If the ratio of the olefin resin is large, the caulking property and cost are advantageous, and if the fluorine resin is large, the sealing property is advantageous.

[Other additives]
In the PBT resin composition of this embodiment, the other additive which can be normally added to a PBT resin composition can be included in the range which does not inhibit the effect of this invention. Other additives include PBT resins, olefin resins, thermoplastic resins excluding fluororesins, antioxidants, stabilizers, lubricants, mold release agents, compatibilizers, colorants, impact modifiers, Examples include hydrolyzable improvers and inorganic fillers having an aspect ratio of less than 3 or more than 200. In addition, as addition amount of another additive, it is preferable that it is 10 mass parts or less with respect to 100 mass parts of PBT resin, and it is more preferable that it is 5 mass parts or less. In particular, when an inorganic filler having an aspect ratio exceeding 200 is added in excess of 10 parts by mass, the caulking property may be disadvantageous.

  In the present embodiment, examples of the sealing member include gaskets, packing, members requiring waterproofness, optical components, condenser lenses, and the like. The PBT resin composition of this embodiment is excellent in sealing properties, heat resistance, and toughness, and is less likely to generate burrs. Therefore, the PBT resin composition is suitable for in-vehicle use that requires heat resistance. In particular, it is suitable for use as a gasket for in-vehicle lithium batteries and a gasket for coin-type or button-type lithium batteries (particularly, primary batteries) because burrs are less likely to occur.

  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.

[Examples 1-7, Comparative Examples 1-7]
In each example and comparative example, a base resin (PBT resin), a polypropylene resin (PP resin), or a polyphenylene sulfide resin (PPS resin), an inorganic filler (talc, mica), and polyethylene (PE) as an olefin resin ) And / or polytetrafluoroethylene (PTFE) as a fluororesin is blended in the number of parts (parts by mass) shown in Tables 1 and 2 below, and has a screw of 30 mmφ (Nippon Steel Co., Ltd.) Manufactured at a cylinder temperature of 260 ° C. to obtain a pellet-shaped PBT resin composition (hereinafter referred to as “resin pellet”).
In addition, the detail of said each component is as follows.

(1) Base resin / PBT resin: PBT resin manufactured by Wintech Polymer Co., Ltd. (intrinsic viscosity: 0.70 dL / g, terminal carboxyl group amount: 19.5 meq / kg)
PP resin: Nippon Polypro Co., Ltd., BC8
PPS resin: Polyplastics PPS resin, DURAFIDE (registered trademark) 0220A9
(2) Inorganic filler / talc: Made by Matsumura Sangyo Co., Ltd., Crown talc PP (average aspect ratio 6, average particle size 13 μm)
-Mica: manufactured by Yamaguchi Mica Co., Ltd., AB-25S (average aspect ratio 80, average particle size 24 μm)
・ Glass flakes: Fine flakes (average aspect ratio 150, average particle size 170 μm), manufactured by Nippon Sheet Glass Co., Ltd.
Glass beads: manufactured by Potters Ballotini Co., Ltd., EMB-10 (average aspect ratio 1, average particle size 5 μm)
Glass fiber: manufactured by Nippon Electric Glass Co., Ltd., ECS03T-747H (average aspect ratio 286, average fiber length 3 mm, average fiber diameter 10.5 μm)
(3) Olefin resin, fluororesin / PE resin: Sanyo Chemical Industries, Sunwax 161-P
・ PTFE: KIT-mura, manufactured by Kitamura Co., Ltd.

[Evaluation]
The following evaluation was performed using the obtained resin pellets.
(1) Sealing property The resin pellets obtained in each of the examples and comparative examples obtained as described above were put into an injection molding machine (manufactured by Nippon Steel Works, Ltd., J-55AD). A disc-shaped test piece having a thickness of 0.5 mm was formed. Using a molded test piece, in accordance with ISO15106-4, using GTR-30XAP G6800T manufactured by GTR Tech Co., Ltd., by differential pressure method, at 85 ° C. and 85% RH atmosphere, 1 mm thickness, 1 m ² area, permeation The moisture permeation amount converted per 24 hours was measured. The case where the moisture permeation amount was 20 g or less was evaluated as ◯, the case where it was more than 20 g and 25 g or less was evaluated as Δ, and the case where it was more than 25 g was evaluated as ×. The results are shown in Tables 1-2.

  As the assembly method of the seal member, assuming the assembly by caulking, the compression characteristics and bending characteristics of the molded products made of the resin pellets of the respective examples and comparative examples were evaluated. This is because, when the seal member is assembled by caulking, since compression stress and bending stress are mainly applied to the seal member, it is required that cracks due to the stress do not occur.

(2) Crimpability 1 (compression characteristics)
The resin pellets of each of the examples and comparative examples were put into an injection molding machine (manufactured by Nippon Steel Works, J-55AD) to form a tensile test piece according to ISO 3167, and 10 × 10 × from the center. A 4 mm test piece was cut out. A compression test was performed with Tensilon UTA-50kN manufactured by Orientec Co., Ltd. so as to apply a load to the 10 × 10 mm surface of the cut specimen. When 50% strain was applied in the thickness direction of the test piece (when the thickness of the test piece was halved), the test piece was taken out from the testing machine and visually observed for the occurrence of cracks in the test piece. The case where the crack did not generate | occur | produce was evaluated as (circle) and the case where the crack has generate | occur | produced as x. The results are shown in Tables 1-2. Except for the determination method, a test was conducted in accordance with ISO604.

(3) Crimpability 2 (bending properties)
The resin pellets of each of the examples and comparative examples were put into an injection molding machine (manufactured by Nippon Steel Works, J-55AD), and an 80 × 10 × 4 mm bending test piece based on ISO 3167 was molded. A bending test was performed with Tensilon RTC-1325A manufactured by Orientec Co., Ltd., except that the molded test piece was used and the span was changed to 32 mm in accordance with ISO178. The case where the fracture strain was 10% or more was evaluated as “◯”, the case where it exceeded 6% and less than 10% was evaluated as “Δ”, and the case where it was 6% or less was evaluated as “X”. The results are shown in Tables 1-2.

(4) Heat resistance The resin pellets of each Example and Comparative Example obtained as described above were put into an injection molding machine (manufactured by Nippon Steel Works, J-55AD) and conformed to ISO 3167. A bending test piece was molded, and a bending test was performed in accordance with ISO178. The test was performed in a constant temperature bath at 60 ° C., and the flexural modulus at high temperature was evaluated. The case where the flexural modulus at 60 ° C. was 1 GPa or more was marked as “◯”, and the case where it was less than 1 GPa was marked as “X”.

(5) Burr The resin pellets obtained in each of the examples and comparative examples obtained as described above were put into an injection molding machine (manufactured by Nippon Steel Works Co., Ltd., J-55AD), and tensile according to ISO 3167. A test piece was molded and the state of occurrence of burrs was visually observed. The case where significant burrs were observed in the molded product was indicated as x, the case where burrs were slightly observed was indicated as Δ, and the case where burrs were hardly observed was indicated as ◯.

  From Table 1, it can be seen that the PBT resin composition of the present invention can be used as a resin composition for a seal member having excellent sealing properties, caulking properties (toughness), heat resistance, and burrs.

Claims (6)

  0.5 to 20 parts by mass of an inorganic filler having an aspect ratio of 3 to 200 and an average particle size of 5 to 300 μm, and an olefin resin and / or a fluorine-based resin with respect to 100 parts by mass of the polybutylene terephthalate resin. The polybutylene terephthalate resin composition for sealing members containing 0.1-20 mass parts of resin.   The polybutylene terephthalate resin composition for a seal member according to claim 1, wherein the seal member is a gasket.   The polybutylene terephthalate resin composition for a seal member according to claim 2, wherein the gasket is for vehicle use.   The polybutylene terephthalate resin composition for sealing members according to claim 2, wherein the gasket is for a lithium battery.   The polybutylene terephthalate resin composition for a seal member according to claim 4, wherein the lithium battery is a coin type or a button type.   The polybutylene terephthalate resin composition for a seal member according to claim 4 or 5, wherein the lithium battery is a primary battery.