JP5742567B2 - Liquid crystalline polyester composition and molded article comprising the same - Google Patents

Description

  The present invention relates to a liquid crystalline polyester composition excellent in fitting property, dielectric strength and low gas property, and a molded product obtained therefrom.

  Due to its liquid crystal structure, liquid crystalline polyester has excellent heat resistance, fluidity, dimensional stability, and flame retardancy. As a result, the application of snap-fit parts is expanding to reduce the number of parts and reduce the number of screws. However, due to the small size and thinness of the molded product, the strength of the snap fit part is insufficient and the fitting property is insufficient, the insulation distance of the molded product is shortened and the tracking performance is reduced, and the small box-like shape When the molded product or the like is used under a sealed high temperature, fogging generated from the surface of the molded product starts to cause problems such as defective insulation and poor contact, and high characteristics are demanded.

  These liquid crystalline polyesters are widely blended with glass fibers for the purpose of improving heat resistance and mechanical strength. Among glass fibers, instead of glass fibers having a circular cross section, eyebrows and oval shapes are used. Studies have been made to improve the dimensional stability and mechanical strength by blending glass fibers having a flat cross section with a crystalline or amorphous thermoplastic resin.

  Examination (for example, patent document 1) which improves the glass fiber filling density of a molded article and improves mechanical strength, dimensional stability, and heat resistance by mix | blending the glass fiber which has non-circle and a circular cross section with liquid crystalline polyester, Study to reduce weld blisters, warpage of molded products, blisters during reflow processing in surface mounting (for example, Patent Documents 2 to 4), crystalline thermoplasticity by blending liquid crystalline polyester with glass fibers having a non-circular cross-sectional shape Studies have been made to improve low warpage, mechanical strength, slidability, etc. by blending resin with glass fibers having a non-circular cross-sectional shape (for example, Patent Documents 5 and 6). As for the resin composition disclosed in the above, there is no dimensional stability such as low warpage after molding and reduction of blistering of molded products during reflow processing in surface mounting. It has been much better.

JP 2008-13702 A JP-A-4-103656 JP 2007-161898 A JP 2003-268252 A Japanese Patent Laid-Open No. 2-173047 JP 2008-214526 A

  However, in recent years, in electrical and electronic parts applications such as connectors, relays, and optical pickups, which are often used in liquid crystalline polyester compositions, the fitting, dielectric strength, and low gas properties are required for further miniaturization and thinning. However, there is a demand for higher performance, and the known methods are not sufficiently satisfactory for these problems.

  In view of the background of such prior art, the present invention has a high snap-fit property at a fitting portion, an excellent tracking resistance that is an index of dielectric strength, and a fogging property that shows fogging due to gas generated on the surface of a molded product. An object of the present invention is to provide a liquid crystalline polyester composition excellent in the above and a molded product obtained therefrom.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a liquid crystalline polyester composition comprising a glass fiber having a non-circular cross-sectional shape with a cross-sectional area in a specific range and a liquid crystalline polyester having a specific composition. The present inventors have found that the product is excellent in snap fit and tracking resistance and has a small amount of gas generated from the surface of the molded product and excellent in fogging properties, and has reached the present invention.

That is, the present invention relates to (1) 100 parts by weight of the liquid crystalline polyester (a) composed of the following structural units (I), (II), (III), (IV), and (V). A liquid crystalline polyester composition comprising 10 to 200 parts by weight of glass fiber (b) having a non-circular cross-sectional shape corresponding to a circle having a diameter ratio of 2 to 5 and a cross-sectional area of 6 to 12 μm in diameter,

(2) The liquid crystalline polyester composition according to (1), further containing 0.1 to 0.5 parts by weight of a tetraester (c) of stearic acid and pentaerythritol with respect to 100 parts by weight of the liquid crystalline polyester.
(3) The liquid crystalline polyester composition according to (1) or (2), wherein glass fibers having a fiber length of 0.1 to 0.6 mm are contained in an amount of 80% by weight or more in all glass fibers,
(4) A molded product formed by melt-molding the liquid crystalline polyester composition according to any one of (1) to (3) above,
(5) The molded product according to (4), wherein the molded product is a part having a fitting portion.

  According to the present invention, it is possible to provide a molded product that is excellent in snap fit and tracking resistance, has a small amount of gas generated from the surface of the molded product, and has excellent fogging properties.

  Hereinafter, the present invention will be described in detail.

  The liquid crystalline polyester (a) of the present invention is a polyester called a thermotropic liquid crystal polymer that exhibits optical anisotropy when melted, and has the following structural units (I), (II), (III), (IV) and ( V).

  The structural unit (I) was generated from p-hydroxybenzoic acid, the structural unit (II) was generated from 4,4′-dihydroxybiphenyl, and the structural unit (III) was generated from hydroquinone. The structural unit, the structural unit (IV) represents a structural unit produced from terephthalic acid, and the structural unit (V) represents a structural unit produced from isophthalic acid.

  Since the liquid crystalline polyester (a) of the present invention comprises the above structural unit, the mesogen length comprising the structural unit (I) is controlled, and the balance between crystallinity and molecular rigidity is excellent. Since the formed product exhibits excellent dimensional stability, it has excellent snap fit. Further, the terminal structure of the liquid crystalline polyester is controlled, and the low gas property is excellent. By blending the glass fiber (b) described later with the liquid crystalline polyester (a), a liquid crystalline polyester composition having excellent snap fit, tracking resistance and fogging properties can be obtained by improving the adhesion between the two. Can do.

  The structural unit (I) is 65 to 80 mol%, particularly preferably 68 to 78 mol%, based on the total of the structural units (I), (II) and (III).

  Further, the structural unit (II) is 55 to 85 mol%, preferably 55 to 78 mol%, more preferably 58 to 73 mol%, based on the total of the structural units (II) and (III). It is.

  The structural unit (IV) is 50 to 95 mol%, preferably 55 to 90 mol%, more preferably 60 to 85 mol%, based on the total of the structural units (IV) and (V). is there.

  Further, the sum of the structural units (II) and (III) and the sum of (IV) and (V) are substantially equimolar. The term “substantially equimolar” as used herein means equimolar as the structural unit constituting the polymer main chain excluding the terminal, and is not necessarily equimolar when the structural unit constituting the terminal is added. Means that.

  When the composition is in a more preferable range, a liquid crystal exhibiting excellent fogging properties by controlling the terminal structure of the liquid crystalline polyester because of excellent balance between toughness and rigidity and good snap fit at the fitting portion. This is preferable because a conductive polyester composition is obtained.

  The melting point (Tm) of the liquid crystalline polyester (a) of the present invention is preferably 220 to 350 ° C., more preferably 270 to 345 ° C., further preferably 300 to 340, from the viewpoint of the balance between processability and heat resistance. ° C.

  Here, the melting point (Tm) is the difference between Tm1 + 20 ° C. after observing the endothermic peak temperature (Tm1) observed when the polymer having been polymerized is measured under the temperature rising condition from room temperature to 20 ° C./min in differential calorimetry. This is the endothermic peak temperature (Tm2) observed when the temperature is held for 5 minutes, then cooled to room temperature under a temperature drop condition of 20 ° C./minute, and measured again under a temperature rise condition of 20 ° C./minute.

  The melt viscosity of the liquid crystalline polyester (a) in the present invention is preferably 1 to 200 Pa · s, more preferably 10 to 100 Pa · s, and still more preferably 20 to 50 Pa · s.

  The melt viscosity is a value measured by a Koka flow tester under the condition of melting point of liquid crystalline polyester + 10 ° C. and shear rate of 1,000 / second.

There is no restriction | limiting in particular in the manufacturing method of liquid crystalline polyester (a) of this invention, It can manufacture according to the well-known polyester polycondensation method. Examples of known polyester polycondensation methods include the following production methods.
(1) A method for producing a liquid crystalline polyester from p-acetoxybenzoic acid and 4,4′-diacetoxybiphenyl, diacetoxybenzene, terephthalic acid and isophthalic acid by a deacetic acid condensation polymerization reaction.
(2) Liquid crystalline polyester by reacting p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl and hydroquinone with terephthalic acid and isophthalic acid with acetic anhydride to acetylate the phenolic hydroxyl group, followed by deacetic acid polymerization How to manufacture.
(3) A method for producing a liquid crystalline polyester from phenyl p-hydroxybenzoate and 4,4′-dihydroxybiphenyl, hydroquinone, diphenyl terephthalate and diphenyl isophthalate by a dephenol polycondensation reaction.
(4) A predetermined amount of diphenyl carbonate is reacted with p-hydroxybenzoic acid and aromatic dicarboxylic acid such as terephthalic acid and isophthalic acid to form phenyl esters, respectively, and then aromatics such as 4,4′-dihydroxybiphenyl and hydroquinone. A method for producing a liquid crystalline polyester by adding a group dihydroxy compound and dephenol polycondensation reaction.

  Among them, (2) p-hydroxybenzoic acid and 4,4′-dihydroxybiphenyl, hydroquinone, terephthalic acid, and isophthalic acid are reacted with acetic anhydride to acetylate the phenolic hydroxyl group, and then liquid crystal is obtained by deacetic acid polycondensation reaction. A method for producing a reactive polyester is preferably used from the viewpoint of polymerization reaction control.

  The amount of acetic anhydride to be used is preferably 1.00 to 1.15 molar equivalent of the total of the phenolic hydroxyl groups of p-hydroxybenzoic acid, 4,4′-dihydroxybiphenyl and hydroquinone, 1.03-1. 12 molar equivalents are more preferred, and 1.05-1.12 molar equivalents are even more preferred. By making the usage-amount of acetic anhydride into the said range, the acetylation rate of hydroquinone with a small acetylation reaction rate can be controlled easily. By controlling the terminal structure of the liquid crystalline polyester, a liquid crystalline polyester composition with less gas generation and excellent fogging properties can be obtained, which is preferable.

  When the liquid crystalline polyester (a) of the present invention is produced by a deacetic acid polycondensation reaction, a melt polymerization method in which the polycondensation reaction is completed by reacting under reduced pressure at a temperature at which the liquid crystalline polyester melts is preferable. The melt polymerization method is an advantageous method for producing a uniform polymer, and is preferable because a polymer with less gas generation and excellent fogging property can be obtained.

  For example, in a reaction vessel equipped with a predetermined amount of p-hydroxybenzoic acid and 4,4′-dihydroxybiphenyl, hydroquinone, terephthalic acid, isophthalic acid, acetic anhydride, a stirring blade, a distillation pipe, and a discharge port at the bottom. There is a method in which the reaction is completed after charging and heating under stirring in a nitrogen gas atmosphere to acetylate the hydroxyl group, raising the temperature to the melting temperature of the liquid crystalline polyester, and performing polycondensation under reduced pressure. The conditions for the acetylation are usually 130 to 300 ° C., preferably 135 to 200 ° C. for 1 to 6 hours, more preferably 140 to 180 ° C. for 2 to 4 hours. The polycondensation temperature is a melting temperature of the liquid crystalline polyester, for example, in the range of 250 to 365 ° C., and preferably a melting point of the liquid crystalline polyester + 10 ° C. or higher. The degree of vacuum during polycondensation is usually 0.1 mmHg (13.3 Pa) to 20 mmHg (2660 Pa), preferably 10 mmHg (1330 Pa) or less, more preferably 5 mmHg (665 Pa) or less. In addition, although acetylation and polycondensation may be performed continuously in the same reaction vessel, acetylation and polycondensation may be performed in different reaction vessels.

  As a method for removing the obtained polymer from the reaction vessel after completion of the polymerization, the inside of the reaction vessel is pressurized to, for example, about 0.02 to 0.5 MPa at a temperature at which the polymer melts, and a discharge port provided at the lower portion of the reaction vessel. There can be mentioned a method of discharging resin in a strand shape, cooling the strand in cooling water, cutting the pellet, and obtaining resin pellets.

  When producing the liquid crystalline polyester (a) of the present invention, the polycondensation reaction can be completed by a solid phase polymerization method. For example, the polymer or oligomer of the liquid crystalline polyester of the present invention is pulverized by a pulverizer and the melting point of the liquid crystalline polyester is −5 ° C. to the melting point −50 ° C. (for example, 200 to 300 ° C.) under a nitrogen stream or under reduced pressure. A method of heating in the range for 1 to 50 hours, polycondensing to a desired degree of polymerization, and completing the reaction can be mentioned.

  Although the polycondensation reaction of the liquid crystalline polyester (a) of the present invention proceeds even without a catalyst, a metal compound such as stannous acetate, tetrabutyl titanate, potassium acetate and sodium acetate, antimony trioxide, and magnesium metal should be used. You can also.

  The glass fiber (b) used in the present invention has a non-circular cross-sectional shape corresponding to a circle having a major axis / minor axis ratio of 2 to 5 and a cross-sectional area of 6 to 12 μm in diameter.

  The major axis / minor axis ratio of the glass fiber (b) having a non-circular cross-sectional shape is defined as the quotient of the longest linear dimension of the glass fiber cross-section and the linear dimension passing through the central axis of the major axis and orthogonal to the major axis. A value obtained by observing a cross section of a glass fiber having a simple cross-sectional shape with a scanning electron microscope, and selecting, for example, 100 glass fibers having a non-circular cross-sectional shape and calculating the number average of the major axis / minor axis ratio It is.

  The ratio of the major axis (longest diameter of the cross section) to the minor axis (shortest diameter perpendicular to the central point of the major axis) of the glass fiber (b) having a non-circular cross-sectional shape is 2 to 5, preferably 3.5. It is -4.5, More preferably, it is 3.8-4.2. When the ratio of the major axis to the minor axis is smaller than 2, the cross-sectional shape is close to a circle, so that the effect of being a non-circular cross section is small, and when it is larger than 5, the effect of improving the mechanical strength cannot be obtained.

  The glass fiber (b) having a non-circular cross-sectional shape has a specific surface area that is larger than that of a glass fiber having an equivalent cross-sectional area and a circular cross-sectional shape. In addition, since the glass fibers are easily oriented and aligned in the flow direction of the molded product, it is estimated that the interfacial peeling between the liquid crystalline polyester and the glass fibers is suppressed after cooling. From these things, since the adhesiveness of liquid crystalline polyester and glass fiber improves, the obtained liquid crystalline polyester composition is excellent in the balance of toughness and rigidity, and is excellent in the snap fit property in a fitting part. In addition, the surface smoothness of the molded product is improved because the adhesion of the liquid crystalline polyester and the glass fiber is prevented from being raised on the surface of the molded product. Therefore, the fitting of the molded product having the fitting portion is facilitated, and the snap fit is improved. Further, by improving the surface smoothness, a minute discharge from the unevenness on the surface of the molded product is reduced when a voltage is applied, and the tracking resistance is improved. Furthermore, since the adhesion between the liquid crystalline polyester and the glass fiber is improved, there are few voids at the interface between the liquid crystalline polyester and the glass fiber, the amount of generated gas is suppressed, and the fogging property is improved.

  Further, the glass fiber (b) having a non-circular cross-sectional shape disturbs the molecular orientation of the liquid crystalline polyester and relaxes anisotropy when blended with the liquid crystalline polyester as compared with the glass fiber having a circular cross section. Therefore, the dimensional stability at the time of shaping | molding of a liquid crystalline polyester composition improves, it is excellent in the fitting in the molded article which has a fitting part, and snap fit property improves.

  Therefore, when the ratio of the major axis to the minor axis of the glass fiber having a non-circular cross-sectional shape is within the scope of the present invention, the adhesion between the liquid crystalline polyester and the glass fiber is higher than when using a glass fiber having a circular cross-sectional shape. Excellent in snapping, tracking resistance and fogging.

  The cross-sectional area of the glass fiber (b) having a non-circular cross-sectional shape is a value corresponding to the cross-sectional area of a circle having a diameter of 6 to 12 μm. When the cross-sectional area of the glass fiber having a non-circular cross-sectional shape is smaller than the value corresponding to the cross-sectional area of a circle having a diameter of 6 μm, spinning in glass fiber production becomes difficult. In particular, the fiber diameter is preferably a value corresponding to the cross-sectional area of a circle having a diameter of 9 μm or more. When the cross-sectional area of a glass fiber having a non-circular cross-sectional shape is larger than the cross-sectional area of a circle having a diameter of 12 μm, it is blended in a liquid crystalline polyester as compared with the glass fiber (b) having a cross-sectional area in the range of the present invention. Sometimes the glass fiber is difficult to break, and the glass fiber longer than the fiber length in the range described later in the liquid crystalline polyester composition increases, so that the glass fiber often floats and protrudes on the surface of the molded product, and the surface smoothness decreases. To do. Moreover, in the case of the said glass fiber, since a specific surface area becomes small compared with the glass fiber (b) which has the cross-sectional area of the range of this invention, the adhesiveness of liquid crystalline polyester and glass fiber falls. They reduce snap fit, tracking resistance and fogging.

  Examples of the non-circular cross-sectional shape of the glass fiber (b) having a major axis / minor axis ratio and a cross-sectional area within the range of the present invention include, for example, oval, eyebrows, oval, semi-circle, arc, or these Similar cross-sectional shape. An oval shape and an eyebrows shape are preferable, and an oval shape is more preferable. The oval mentioned here is different from an oval, and includes two or more parallel shapes such as a rounded quadrangle, an ellipse having parallel straight portions, or a shape formed by combining a rectangle and two semicircles. A shape having a straight part and a part of a circle at two or more locations is included. The use of glass fibers having an oval cross-sectional shape is preferable because the strength and dimensional stability are higher than those of an elliptical or eyebrow-shaped cross-sectional shape.

  The blending ratio of the glass fiber (b) having a non-circular cross-sectional shape is 10 to 200 parts by weight, preferably 20 parts by weight or more, more preferably 30 parts by weight or more with respect to 100 parts by weight of the liquid crystalline polyester (a). preferable. On the other hand, 150 parts by weight or less is preferable, and 100 parts by weight or less is more preferable. When the blending ratio of the glass fiber is less than 10 parts by weight, the reinforcing effect of the glass fiber is small, the surface smoothness and dimensional stability are not improved, and the effect of the present invention is not sufficiently exhibited. Moreover, when there are more compounding ratios of glass fiber than 200 weight part, since the orientation of liquid crystalline polyester is disturbed largely, fluidity | liquidity will be impaired, and the balance of toughness and rigidity will be bad and snap fit property will fall.

  The liquid crystalline polyester composition containing the glass fiber (b) of the present invention, which is in the above preferred range, is a glass fiber having a circular cross section or a glass fiber having a non-circular cross sectional shape having a cross sectional area outside the range of the present invention. It is characterized by having excellent snap fit and tracking resistance, which were not obtained when blended with, and specifically improving fogging properties.

  As the glass fiber length in the liquid crystalline polyester composition of the present invention, the number of 0.1 to 0.6 mm is preferably 80% by weight or more, more preferably 85% by weight or more, and still more preferably 90%. % By weight or more. The glass fiber having a non-circular cross-sectional shape and having a cross-sectional area within the range of the present invention is controlled to be easily broken when kneaded with the liquid crystalline polyester, and the distribution of the glass fiber length within the above range is obtained. can get.

  When the glass fiber length is within the above range, the distribution of the glass fiber length in the liquid crystalline polyester composition becomes sharp and glass fibers having a uniform fiber length exist. As a result, the number of glass fibers with a fiber length of 0.6 mm or more is reduced, and the glass fibers are less projected to the surface of the molded product, resulting in excellent surface smoothness and dimensional stability, and accordingly snap fit and tracking resistance. More improved. Moreover, the short glass fiber whose fiber length is 0.1 mm or less decreases, and the liquid crystalline polyester composition can express sufficient mechanical strength and heat resistance. Here, the fiber length of the glass fiber in the composition is that the pellet made of the liquid crystalline polyester composition is placed in a crucible and ashed in a 600 ° C. electric furnace, and then the remaining glass fiber is dispersed in soapy water. It can be obtained by observing under an optical microscope and measuring the fiber length of the photographed glass fiber. Measurement is performed by measuring 500 or more fibers and calculating the weight% of the fiber length of 0.1 to 0.6 mm.

  The glass fiber (b) used in the present invention is preferably treated with an epoxy-based, urethane-based, acrylic-based coating or sizing agent, and the surface thereof is treated with a coupling agent such as γ- (2-amino). Ethyl) aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, hydroxypropyltrimethoxysilane, γ-ureidopropyl Silane coupling agents such as triethoxysilane and vinylacetoxysilane, isopropyltrisisostearoyl titanate, isopropyltris (dioctylpyrophosphate) titanate, tetraoctylbis (ditridecylphosphite) titanate, Coupling with titanium coupling agents such as bis (dioctylpyrophosphate) ethylene titanate, isopropyltridecylbenzenesulfonyl titanate, isopropyltri (dioctylphosphate) titanate, and aluminum coupling agents such as acetoalkoxyaluminum diisopropylate Also good.

  The type of the glass fiber (b) used in the present invention is not limited to the above-mentioned non-circular cross-sectional shape and cross-sectional area within the scope of the present invention, as long as it is generally used for resin reinforcement. There is no limitation, for example, it can select and use from a chopped strand, a milled fiber, etc. of a long fiber type or a short fiber type. As the glass fiber used in the present invention, a weakly alkaline glass fiber is excellent in terms of mechanical strength and can be preferably used. In particular, glass fibers having a silicon oxide content of 50 to 80% by weight are preferably used, and more preferably glass fibers having a silicon oxide content of 65 to 77% by weight.

  The glass fiber (b) used in the present invention may be coated or bundled with a thermoplastic resin such as an ethylene / vinyl acetate copolymer or a thermosetting resin such as an epoxy resin.

  In the liquid crystalline polyester composition of the present invention, a filler other than the glass fiber (b) having a non-circular cross section can be further mixed and used as a resin composition within a range not impairing the effects of the present invention. Examples of the filler herein include fillers such as a fiber, a plate, a powder, and a granule. Specifically, glass fibers having a circular cross section, PAN-based and pitch-based carbon fibers, stainless steel fibers, metal fibers such as aluminum fibers and brass fibers, organic fibers such as aromatic polyamide fibers and liquid crystalline polyester fibers, and gypsum fibers , Ceramic fiber, asbestos fiber, zirconia fiber, alumina fiber, silica fiber, titanium oxide fiber, silicon carbide fiber, rock wool, potassium titanate whisker, barium titanate whisker, aluminum borate whisker, silicon nitride whisker, acicular titanium oxide Fibrous or whisker-like fillers such as mica, talc, kaolin, silica, glass beads, glass flakes, clay, molybdenum disulfide, wollastonite, titanium oxide, zinc oxide, calcium polyphosphate and graphite Plate-like Hama material and the like.

  The above-mentioned filler used in the present invention can also be used by treating the surface thereof with the above coupling agent or other surface treatment agent. Moreover, you may use the said filler in combination of 2 or more types.

  The liquid crystalline polyester composition of the present invention preferably further contains a tetraester (c) of stearic acid and pentaerythritol. As a result, the gap at the interface between the liquid crystalline polyester (a) and the glass fiber (b) having a non-circular cross-sectional shape is reduced and the adhesion is improved. Therefore, the cross-sectional area and non-circular cross-sectional shape within the scope of the present invention are reduced. The effect of the surface smoothness of the molded product of the liquid crystalline polyester composition using the glass fiber is improved, and as a result, the molded product having the fitting portion can be easily fitted and the snap fit is improved. Further, since the surface smoothness is further improved, when a voltage is applied to the molded product of the liquid crystalline polyester composition, a slight discharge from the irregularities on the surface of the molded product is reduced, and the tracking resistance is improved. Furthermore, by improving the adhesiveness between the liquid crystalline polyester and the glass fiber, there are few voids at the interface between the liquid crystalline polyester and the glass fiber, the amount of gas generated from the surface of the molded product is suppressed, and the fogging property is improved. In addition, because it contains a tetraester of stearic acid and pentaerythritol, the surface of the molded product at the time of mold release and deformation due to protruding pins are suppressed, so the dimensional stability of the molded product is excellent, and fitting Excellent fit with molded product having a part, and snap fit is further improved.

  The amount of tetraester (c) of stearic acid and pentaerythritol is 0.1 to 0.5 parts by weight, more preferably 0.3 to 0.5 parts by weight per 100 parts by weight of the liquid crystalline polyester. Part. When the blending amount of the tetraester of stearic acid and pentaerythritol is within the above range, the surface smoothness of the molded product is excellent because of excellent adhesion at the interface between the liquid crystalline polyester and the glass fiber having a non-circular cross-sectional shape. Since the dimensional stability is improved and the gap at the interface between the liquid crystalline polyester and the glass fiber is reduced, the effect of the present invention can be increased.

  In the liquid crystalline polyester composition of the present invention, an antioxidant and a heat stabilizer (for example, hindered phenol, hydroquinone, phosphites and their substitutes), an ultraviolet absorber (in the range not impairing the effects of the present invention) For example, anti-coloring agents such as resorcinol and salicylate, phosphites, hypophosphites, etc., release agents other than lubricants and tetraesters of stearic acid and pentaerythritol (montanic acid and metal salts thereof, esters thereof, Half esters, stearyl alcohol, stearamide and polyethylene wax, etc.), colorants including dyes and pigments, carbon black, crystal nucleating agents, plasticizers, flame retardants (bromine flame retardants, phosphorus flame retardants, etc.) Red phosphorus, silicone flame retardant, etc.), flame retardant aid, and antistatic Usual additives such as, by blending the polymer other than the liquid crystal polyester can further impart predetermined properties.

  The liquid crystalline polyester composition of the present invention is preferably produced by melt kneading, and a known method can be used for melt kneading. For example, a Banbury mixer, a rubber roll machine, a kneader, a single-screw or twin-screw extruder can be used. Among these, from the viewpoint of controlling the glass fiber length in the liquid crystalline polyester composition, it is preferable to use an extruder, more preferably a twin screw extruder, and in particular, a glass fiber having a non-circular cross-sectional shape. It is particularly preferable to use a twin-screw extruder having a side feed portion for adding the from the middle portion of the extruder. As kneading methods, 1) Filler and other additives excluding glass fiber having a non-circular cross-sectional shape, and other additives are added all at once from the original feeder and kneaded, and then have a non-circular cross-sectional shape. Method of adding and kneading glass fiber and other fillers and additives from side feeder if necessary (side feed method), 2) Liquid crystalline polyester composition containing liquid crystalline polyester and other additives in high concentration (Master pellet) is prepared, and then the master pellet is kneaded with liquid crystalline polyester so as to have a specified concentration, and then glass fiber having a non-circular cross-sectional shape and, if necessary, side-feeding other fillers. Any method such as (master pellet + side feed method) may be used.

  The screw rotation speed of the twin screw extruder is not particularly limited as long as the glass fiber length in the liquid crystalline polyester composition is 0.1 to 0.6 mm, and the number of screw rotations is not particularly limited. If the amount is too large, the shear force applied to the liquid crystalline polyester composition will increase, so the glass fiber length will be shortened.If the screw rotation speed is too small, the discharge rate will decrease and the productivity will decrease. It is preferable to set an appropriate value in accordance with the composition and the twin screw extruder.

  However, the above additives may be melt-kneaded in a twin-screw extruder together with the liquid crystalline polyester composition, but may be blended (eg, tumbler mixer, ribbon blender, etc.) to the pellets after melt-kneading extrusion. .

  The liquid crystalline polyester composition of the present invention is melt-molded by ordinary molding methods such as injection molding, extrusion molding, and press molding, and has excellent surface appearance (color tone), mechanical properties, heat resistance, and flame retardancy. Can be processed into products.

  Examples of the molded product include injection molded products, extrusion molded products, press molded products, sheets, pipes, films, fibers, and the like, and particularly fitting parts such as connectors, relays, optical pickups, LED lamps, coil bobbins, and the like. Since the effects of the present invention can be remarkably obtained in molded articles having the above, injection molded articles that can be easily processed into those molded articles are preferred.

  Molded articles made of the liquid crystalline polyester composition thus obtained include, for example, various gears, various cases, sensors, LED lamps, connectors, sockets, resistors, relay cases, relay bases, relay spools, switches, Coil bobbin, condenser, variable capacitor case, optical pickup, oscillator, various terminal boards, transformer, plug, printed wiring board, tuner, speaker, microphone, headphones, small motor, magnetic head base, power module, housing, semiconductor, liquid crystal display Parts, FDD carriage, FDD chassis, HDD parts, motor brush holder, parabolic antenna, electric / electronic parts represented by computer-related parts, VTR parts, TV parts, irons, hair dryers, rice cookers Parts, microwave oven parts, acoustic parts, audio equipment parts such as audio / laser discs / compact discs, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts, home appliances, office appliance parts, offices Machine-related parts such as computer-related parts, telephone-related parts, facsimile-related parts, copier-related parts, cleaning jigs, oilless bearings, stern bearings, underwater bearings, motor parts, lighters, typewriters, etc. Parts, microscopes, binoculars, cameras, optical instruments such as watches, precision machine parts, alternator terminals, alternator connectors, IC regulators, light dimmer potentiometer bases, various valves such as exhaust gas valves, fuel related / exhaust System / intake system pipes, air intake nozzle snorkel, intake manifold, fuel pump, engine coolant joint, carburetor main body, carburetor spacer, exhaust gas sensor, coolant sensor, oil temperature sensor, throttle position sensor, crankshaft position sensor , Air flow meter, brake butt wear sensor, thermostat base for air conditioner, motor insulator for air conditioner, automotive motor insulator such as power window, heating air flow control valve, brush holder for radiator motor, water pump impeller, turbine vane, Wiper motor related parts, distributor, starter switch, starter relay, transmitter Wiring harness, window washer nozzle, air conditioner panel switch board, coil for fuel solenoid valve, fuse connector, horn terminal, electrical component insulation plate, step motor rotor, lamp bezel, lamp socket, lamp reflector, lamp housing, brake It can be used for automobile / vehicle-related parts such as pistons, solenoid bobbins, engine oil filters, and ignition device cases. Among them, in order to express the effects of excellent snap fit, tracking resistance and fogging by incorporating glass fiber having a non-circular cross-sectional shape with a fiber diameter within the scope of the present invention, the fitting portion is provided. It is useful for small electrical / electronic components, such as connectors, relays, optical pickups, LED lamps, and coil bobbins.

  Hereinafter, although an example explains the present invention still in detail, the gist of the present invention is not limited only to the following example.

  The composition analysis and characteristic evaluation of the liquid crystalline polyester were performed by the following methods.

(1) Melting | fusing point (Tm) measurement of liquid crystalline polyester Endothermic peak temperature (Tm1) observed when it measures on 20 degree-C / min temperature rising conditions from differential scanning calorimeter DSC-7 (made by Perkin Elmer). After the observation, the sample was held at a temperature of Tm1 + 20 ° C. for 5 minutes, then once cooled to room temperature under a temperature drop condition of 20 ° C./min, and the endothermic peak temperature observed when measured again under a temperature rise condition of 20 ° C./min ( Tm2) was taken as the melting point. In the following production examples, the melting point is described as Tm.

(2) Melt viscosity measurement of liquid crystalline polyester Koka flow tester CFT-500D (orifice 0.5φ × 10 mm) (manufactured by Shimadzu Corporation) was used, the temperature was the melting point of liquid crystalline polyester + 10 ° C., and the shear rate was 1000 / sec. Measured with

Production Example 1
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 932 parts by weight of p-hydroxybenzoic acid, 251 parts by weight of 4,4′-dihydroxybiphenyl, 99 parts by weight of hydroquinone, 284 parts by weight of terephthalic acid, 90 parts by weight of isophthalic acid And 1252 parts by weight of acetic anhydride (1.09 equivalents of total phenolic hydroxyl groups) were allowed to react at 145 ° C. for 1 hour with stirring in a nitrogen gas atmosphere, and then heated from 145 ° C. to 350 ° C. over 4 hours. I let you. Thereafter, the polymerization temperature was maintained at 350 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.0 hour, the reaction was continued, and the polycondensation was completed when the torque reached 20 kg · cm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm ² (0.1 MPa), the polymer was discharged to a strand-like material via a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  This liquid crystalline polyester (a-1) is derived from a structural unit derived from p-hydroxybenzoic acid (structural unit (I)), a structural unit derived from 4,4′-dihydroxybiphenyl (structural unit (II)), and hydroquinone. The ratio of the structural unit derived from p-hydroxybenzoic acid (structural unit (I)) to the sum of the structural units (structural unit (III)) is 75 mol%, the structural unit derived from 4,4′-dihydroxybiphenyl (structural unit ( II)) and hydroquinone-derived structural unit (structural unit (III)), the proportion of 4,4′-dihydroxybiphenyl-derived structural unit (structural unit (II)) is 60 mol%, terephthalic acid-derived structural unit Ratio of structural unit derived from terephthalic acid (structural unit (IV)) to structural unit derived from (structural unit (IV)) and structural unit derived from isophthalic acid (structural unit (V)) There was 76 mol%, Tm is 330 ° C., a melt viscosity of 28 Pa · s.

Production Example 2
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 845 parts by weight of p-hydroxybenzoic acid, 322 parts by weight of 4,4′-dihydroxybiphenyl, 127 parts by weight of hydroquinone, 421 parts by weight of terephthalic acid, 57 parts by weight of isophthalic acid And 1322 parts by weight of acetic anhydride (1.09 equivalents of the total phenolic hydroxyl groups) were allowed to react at 145 ° C. for 1 hour with stirring in a nitrogen gas atmosphere, and then heated from 145 ° C. to 350 ° C. over 4 hours. I let you. Thereafter, the polymerization temperature was maintained at 350 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.0 hour, the reaction was continued, and the polycondensation was completed when the torque reached 20 kg · cm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm ² (0.1 MPa), the polymer was discharged to a strand-like material via a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  In this liquid crystalline polyester (a-2), the ratio of the structural unit (I) to the total of the structural unit (I), the structural unit (II), and the structural unit (III) is 68 mol%, and the structural unit (II) and the structure The ratio of the structural unit (II) to the total of the units (III) is 60 mol%, the ratio of the structural unit (IV) to the structural unit (IV) and the structural unit (V) is 88 mol%, Tm is 342 ° C., The melt viscosity was 21 Pa · s.

Production Example 3
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 870 parts by weight of p-hydroxybenzoic acid, 352 parts by weight of 4,4′-dihydroxybiphenyl, 89 parts by weight of hydroquinone, 292 parts by weight of terephthalic acid, 157 parts by weight of isophthalic acid And 1302 parts by weight of acetic anhydride (1.09 equivalents of total phenolic hydroxyl groups) were allowed to react at 145 ° C. for 1 hour with stirring in a nitrogen gas atmosphere, and then heated from 145 ° C. to 330 ° C. over 4 hours. I let you. Thereafter, the polymerization temperature was maintained at 330 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.0 hour, the reaction was further continued, and the polycondensation was completed when the torque reached 20 kg · cm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm ² (0.1 MPa), the polymer was discharged to a strand-like material via a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  In this liquid crystalline polyester (a-3), the ratio of the structural unit (I) to the total of the structural unit (I), the structural unit (II), and the structural unit (III) is 70 mol%, and the structural unit (II) and the structure The ratio of the structural unit (II) to the total of the units (III) is 70 mol%, the ratio of the structural unit (IV) to the structural unit (IV) and the structural unit (V) is 65 mol%, Tm is 310 ° C., The melt viscosity was 30 Pa · s.

Production Example 4
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 994 parts by weight of p-hydroxybenzoic acid, 126 parts by weight of 4,4′-dihydroxybiphenyl, 112 parts by weight of terephthalic acid, 216 parts by weight of polyethylene terephthalate isophthalic acid and acetic anhydride 960 parts by weight (1.10 equivalents of the total phenolic hydroxyl groups) was charged and reacted at 145 ° C. for 1 hour with stirring in a nitrogen gas atmosphere, and then heated from 145 ° C. to 320 ° C. over 4 hours. Thereafter, the polymerization temperature was maintained at 320 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.0 hour, the reaction was continued, and the polycondensation was completed when the torque reached 20 kg · cm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm ² (0.1 MPa), the polymer was discharged to a strand-like material via a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  This liquid crystalline polyester (a-4) has a structural unit (I) of 66.7 mol%, a structural unit (II) of 6.3 mol%, an ethylenedioxy unit derived from polyethylene terephthalate of 10.4 mol%, The structural unit (IV) was 16.6 mol%, the Tm was 313 ° C., and the melt viscosity was 13 Pa · s.

Production Example 5
In a 5 L reaction vessel equipped with a stirring blade and a distillation pipe, 24.9 parts by weight of p-hydroxybenzoic acid, 812.9 parts by weight of 6-hydroxy-2-naphthoic acid, 41,4′-dihydroxybiphenyl 419.0 Parts by weight, 373.8 parts by weight of terephthalic acid, and 964.8 parts by weight of acetic anhydride (1.05 equivalents of the total phenolic hydroxyl group), and after reacting at 145 ° C. for 1 hour with stirring under a nitrogen gas atmosphere, The temperature was raised from 145 ° C. to 360 ° C. in 4 hours. Thereafter, the polymerization temperature was maintained at 360 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.0 hour, the reaction was continued, and the polycondensation was completed when the torque reached 20 kg · cm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm ² (0.1 MPa), the polymer was discharged to a strand-like material via a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  In this liquid crystalline polyester (a-5), the structural unit (I) is 2 mol%, the 6-oxy-2-naphthalate unit is 48 mol%, the structural unit (II) is 25 mol%, and the structural unit (IV) is 25 mol%. Mol%, Tm was 350 ° C., and melt viscosity was 25 Pa · s.

  The composition of the liquid crystalline polyester obtained in each production example is shown in Table 1.

  The fillers and additives used in each example and comparative example are shown below.

Filler (b-1): Nittobo flat fiber (CSG3J-831), cross-sectional shape of oval (track shape having parallel straight portions), ratio of major axis (20 μm) / minor axis (5 μm) 4, diameter 11 μm A cross-sectional area equivalent to glass fiber having a circular cross-sectional shape, and a fiber length of 3 mm.
(B-2): Nittobo flat fiber (CSG3PA-820), cross-sectional shape of an oval (track shape having parallel straight portions), a long diameter (28 μm) / short diameter (7 μm) ratio of 4 and a circular shape of 15 μm in diameter The cross-sectional area equivalent to the glass fiber of the cross-sectional shape, fiber length 3 mm.
(B-3): Nittobo flat fiber (CSH3PA-870), cross-sectional shape of eyebrows, cross-sectional area equivalent to glass fiber having a circular cross-sectional shape with a long diameter (20 μm) / short diameter (10 μm) ratio of 2 and a diameter of 15 μm , Fiber length 3 mm.
(B-4): Nippon Electric Glass E glass chopped strand (ECS-03T790DE), circular cross-sectional shape (major axis / minor axis ratio 1), fiber diameter 6.5 μm, fiber length 3 mm.
(B-5): Nippon Electric Glass E glass chopped strand (ECS-03T747H / P), circular cross-sectional shape (major axis / minor axis ratio 1), fiber diameter 10 μm, fiber length 3 mm.

Additive (c-1): Pentaerythritol tetrastearate (LOXIOLVPG861 manufactured by Cognis Japan)
(C-2): Montanic acid glycol ester (Clariant Lycowax E)

Examples 1-7, Comparative Examples 1-9
Liquid crystalline polyester (a-1 to a-5) obtained in the production example with a blending amount shown in Table 2 with respect to 100 parts by weight of the liquid crystalline polyester using a TEM35B type twin screw extruder manufactured by Toshiba Machine with a side feeder. And additives (c-1, c-2) are charged from the hopper, fillers (b-1 to b-5) are charged from the side, the cylinder temperature is set to the melting point of the liquid crystalline polyester + 10 ° C., and the screw The rotational speed was set to 150 rpm, and melt kneaded to obtain pellets. However, in Example 3, the screw rotation speed was 175 rpm, and in Example 4, the screw rotation speed was 200 rpm. The pellets of the obtained liquid crystalline polyester composition were preliminarily dried at 130 ° C. for 3 hours with a hot air dryer, and then evaluated as (1) to (4) below. The results are shown in Table 2.

(1) Evaluation of snap fit properties The liquid crystalline polyester compositions of Examples 1 to 7 and Comparative Examples 1 to 9 were subjected to a FANUC α30C injection molding machine (FANUC screw diameter 28 mm), and the cylinder temperature was the melting point of the liquid crystalline polyester +10. A molded product with a box shape of inner diameter vertical 50 × horizontal 80 × height 5 × wall pressure 4 mm, with claw 0.8 mm thick × 2 mm long and square plate 50 × 80 × 1 mm thick Was molded, and the center of the square plate was pushed to perform 30 fitting tests on the box-formed product. The snap-fit property was evaluated based on the number of the nail of the box-shaped product that was not broken and the square plate was fitted. The larger the number, the better the snap fit.

(2) Tracking resistance evaluation The liquid crystalline polyester compositions of Examples 1 to 7 and Comparative Examples 1 to 9 were subjected to a FANUC α30C injection molding machine (FANUC screw diameter 28 mm), and the cylinder temperature was the melting point of the liquid crystalline polyester +10. A square plate having a thickness of 50 × 80 × 1 mm was molded at 0 ° C., and a comparative tracking index (CTI) was measured according to the test method of IEC1121 (A solution). It can be said that the higher the value, the better the tracking resistance.

(3) Evaluation of fogging properties 5 g of the liquid crystalline polyester compositions of Examples 1 to 7 and Comparative Examples 1 to 9 were weighed into test tubes (outer diameter 18.0 mm × height 75 mm) to obtain measurement samples. A sample test tube was inserted into a drive lock bath (manufactured by Synics Co., Ltd.) containing two aluminum blocks each having a hole diameter of φ18.5 mm × 71 mm, and a slide glass was placed on the test tube opening. Heat treatment is performed for a period of time, and the gas generated at this time is deposited on the slide glass. Thereafter, the haze value (cloudiness) of the slide glass is measured with a direct reading haze meter (manufactured by Toyo Seiki Co., Ltd.). The smaller the haze value, the less fogging and the better the fogging property, and the higher the haze value, the more the glass becomes cloudy and the fogging property is inferior.

(4) Evaluation of glass fiber length distribution 10 g of the liquid crystalline polyester composition pellets of Examples 1 to 7 and Comparative Examples 1 to 9 were placed in a crucible and incinerated in an electric furnace at 600 ° C., and then the remaining glass. Disperse the fibers in soapy water, observe using an optical microscope, take a photograph at 10000x, and measure the fiber length of 1000 glass fibers at 120x magnification using image analysis software ("Quick Grain Standard" manufactured by Innotech). The weight% of the fiber length of 0.1 to 0.6 mm was calculated. The more glass fibers in the above range, the more uniform the glass fiber length in the liquid crystalline polyester composition and the sharper the distribution.

  From Table 2, it can be seen that the liquid crystalline polyester composition of the present invention is excellent in snap fit, tracking resistance, and fogging, and is therefore suitable for small precision molded products for electrical / electronic applications having fitting portions. .

  The liquid crystalline polyester composition of the present invention is useful for small precision molded products for electrical and electronic applications having fitting parts such as connectors, relays and optical pickups that require snap fit, tracking resistance and fogging. is there.

Claims (5)

The major axis / minor axis ratio is 2 to 5 with respect to 100 parts by weight of the liquid crystalline polyester (a) composed of the following structural units (I), (II), (III), (IV) and (V). A liquid crystalline polyester composition comprising 10 to 200 parts by weight of glass fiber (b) having a non-circular cross-sectional shape corresponding to a circle having a diameter of 6 to 12 μm.

The liquid crystalline polyester composition according to claim 1, comprising 0.1 to 0.5 parts by weight of tetraester (c) of stearic acid and pentaerythritol with respect to 100 parts by weight of the liquid crystalline polyester. The liquid crystalline polyester composition according to claim 1 or 2, wherein glass fibers having a fiber length of 0.1 to 0.6 mm are contained in an amount of 80% by weight or more in all glass fibers. The molded product formed by melt-molding the liquid crystalline polyester composition in any one of Claims 1-3. The molded product according to claim 4, wherein the molded product is a part having a fitting portion.