JP2008208257A - Manufacturing method of l-shaped molded article consisting of liquid crystalline resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an L-shaped molded article showing, when the bending part is subject to a force, excellent strengths without damaging the characteristics of a liquid crystalline resin. <P>SOLUTION: In manufacturing the L-shaped molded article consisting of a crystalline resin composition containing 20-90 pts.wt. of a fibrous filler based on 100 pts.wt. of a crystalline resin, the manufacturing method is characterized in that the injection molding is carried out with the gate position set to the part 10 mm or more far from the L-shaped bending part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an L-shaped molded article comprising a liquid crystal resin composition having excellent bending portion rigidity.

  In recent years, electrical equipment has been reduced in size and performance, and it has become essential to reduce the size, thickness, and density of the components that make up it. It has come to be actively performed.

  Therefore, the characteristics required for liquid crystal resins are diversified. For example, among others, liquid crystalline resins have been widely used as small electrical and electronic component materials such as FPC connectors because of their excellent fluidity and high heat resistance. Since these parts are functional parts and are hardly subjected to external stress, the rigidity and toughness exhibited by conventional liquid crystalline resins were sufficient, but structural members that require mechanical strength Application to was difficult. In particular, since it is excellent in fluidity, jetting is likely to occur at the time of injection molding, and as a result, air is filled while being entrained. As a result, voids are formed inside the molded product, resulting in a decrease in mechanical strength. Further, since the liquid crystalline resin has particularly weak weld strength, an extra portion is intentionally designed so that the weld line does not appear on the product, and the portion is removed (for example, Patent Document 1).

On the other hand, like the weld line, the liquid crystalline resin molded product shows weaker strength than the portion where the molecular orientation is strong because the molecular orientation is disturbed near the gate. Generally, the gate position is designed in consideration of the weld line and the installation to the product part where there is no gate residue. For example, when molding a molded product with a bent part that requires strength If a gate is installed in the vicinity of the bent portion, the strength that the liquid crystalline resin should originally exhibit cannot be exhibited, and a good product may not be obtained.
Japanese Patent Laid-Open No. 9-293338

  The present invention provides an L-shaped molded article comprising a liquid crystalline resin composition capable of producing an L-shaped molded article having excellent strength when a force is applied to a bent portion without impairing the properties of the liquid crystalline resin. It is an object to provide a manufacturing method.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a method for producing a liquid crystalline resin molded body that maximizes the strength of the bent portion originally exhibited by the liquid crystalline resin composition, and complete the present invention. It reached.

  That is, the manufacturing method of the L-shaped molded article which consists of a liquid crystalline resin composition of this invention consists of the structure of the following (1).

(1) When manufacturing an L-shaped molded product comprising a liquid crystalline resin composition containing 20 to 90 parts by weight of a fibrous filler with respect to 100 parts by weight of a liquid crystalline resin, the L-shaped bending A method for producing an L-shaped molded product comprising a liquid crystalline resin composition, wherein a gate position is set at a portion separated by 10 mm or more from the portion and injection molding is performed.

  Moreover, in the manufacturing method of the L-shaped molded article which consists of this liquid crystalline resin composition of this invention, More preferably, it consists of the structure in any one of the following (2)-(5).

(2) The L-shaped molded article comprising the liquid crystalline resin composition according to (1), wherein the fibrous filler is composed of glass fibers having a number average fiber diameter of 6 μm to 20 μm. Manufacturing method.

(3) An L-shaped molded article comprising the liquid crystalline resin composition according to (1) or (2) above, wherein the gate cross-sectional shape is a regular n-square shape or a circular shape with n = 5 or more Production method.

(4) The gate cross-sectional shape is a regular n-corner shape or circular shape with n = 5 or more, and the length of the longest diagonal line of the regular n-corner shape or the diameter of the circular shape is 3 mm or less. A method for producing an L-shaped molded article comprising the liquid crystalline resin composition as described in (3) above.

(5) The L-shaped molded product comprising the liquid crystalline resin composition according to any one of (1) to (4) above, wherein the molded product to be molded has a maximum thickness of 5 mm or less. Production method.

  According to the method of the present invention, as described below, an L-shaped molded product of the liquid crystalline resin composition in which the rigidity of the bent portion originally exhibited by the liquid crystalline resin is maximized can be obtained.

  Furthermore, according to the method of the present invention, a molded product made of a liquid crystalline resin composition with few impurities such as low oligomers can be obtained, and thus has a great effect on the manufacture of insulators for motors such as air conditioners and refrigerators.

  The manufacturing method of the L-shaped molded article of the present invention comprises an L-shaped molded article comprising a liquid crystalline resin composition containing 20 to 90 parts by weight of a fibrous filler with respect to 100 parts by weight of the liquid crystalline resin. At the time of manufacture, the gate position is set at a portion separated from the L-shaped bent portion by 10 mm or more and injection molding is performed.

  In the present invention, what is important is that the installation position of the gate is set at a portion that is 10 mm or more away from the L-shaped bent portion, and is less than 10 mm away from the L-shaped bent portion. In the bent portion, the molecular orientation of the liquid crystalline resin is found and the mechanical strength is lowered.

  Examples of the liquid crystalline resin used in the present invention include a liquid crystalline polyester and a liquid crystalline polyester amide that form an anisotropic molten phase, and specific examples thereof include an aromatic oxycarbonyl unit, an aromatic dioxy unit, an aromatic Liquid crystalline polyester forming an anisotropic melt phase comprising a structural unit selected from an aromatic dicarbonyl unit, an ethylenedioxy unit, and the like, and the structural unit and an aromatic iminocarbonyl unit, an aromatic diimino unit, an aromatic iminooxy unit And a liquid crystalline polyester amide that forms an anisotropic molten phase composed of a structural unit selected from the above.

（ただし式中のＲ_１ は、

から選ばれた一種以上の基を示し、Ｒ_２ は、

から選ばれた一種以上の基を示す。また、式中Ｘは水素原子または塩素原子を示し、構造単位（II）および（III）の合計と構造単位（IV）は実質的に等モルである。） Examples of the liquid crystalline polyester forming the anisotropic melt phase are preferably liquid crystalline polyesters comprising the following structural units (I), (II) and (IV), (I), (II), (III ) And (IV) structural units, and liquid crystalline polyesters (I), (III) and (IV).

(However, R ₁ in the formula is

One or more groups selected from R ₂ ,

One or more groups selected from In the formula, X represents a hydrogen atom or a chlorine atom, and the total of the structural units (II) and (III) and the structural unit (IV) are substantially equimolar. )

であり、Ｒ_２ が

であるものが特に好ましい。 The structural unit (I) is a structural unit of a polyester formed from p-hydroxybenzoic acid, and the structural unit (II) is 4,4′-dihydroxybiphenyl, 3,3 ′, 5,5′-tetramethyl. -4,4'-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, phenylhydroquinone, methylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane and 4 , 4′-dihydroxydiphenyl ether selected from one or more aromatic dihydroxy compounds, the structural unit (III) is a structural unit generated from ethylene glycol, the structural unit (IV) is terephthalic acid, Isophthalic acid, 4,4′-diphenyldicarboxylic acid, 2,6-naphthalene Dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4′-dicarboxylic acid and 1,2-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylic acid Each of the structural units generated from one or more aromatic dicarboxylic acids selected from Of these, R ₁ is

And R ₂ is

Are particularly preferred.

  Examples of liquid crystalline polyester amides include 6-hydroxy-2-naphthoic acid, liquid crystalline polyester amide formed from p-aminophenol and terephthalic acid, p-hydroxybenzoic acid, 4,4′-dihydroxybiphenyl and terephthalic acid. Examples thereof include liquid crystalline polyesteramides (Japanese Patent Laid-Open No. 64-33123) formed from acid, p-aminobenzoic acid and polyethylene terephthalate.

  The liquid crystalline polyester that can be preferably used in the present invention is a copolymer comprising the above structural units (I), (II) and (IV), or comprising (I), (II), (III) and (IV). It is a copolymer, and the copolymerization amount of the structural units (I), (II), (III) and (IV) is arbitrary. However, the following copolymerization amount is preferable from the viewpoint of fluidity.

  That is, when the structural unit (III) is included, from the viewpoint of heat resistance, flame retardancy and mechanical properties, the total of the structural units (I) and (II) is the structural unit (I), (II). And 60-95 mol% is preferable with respect to the sum total of (III), and 75-93 mol% is more preferable. Further, the structural unit (III) is preferably 40 to 5 mol%, more preferably 25 to 7 mol%, based on the total of the structural units (I), (II) and (III). The molar ratio [(I) / (II)] of the structural unit (I) to the structural unit (II) is preferably 75/25 to 95/5 from the viewpoint of the balance between heat resistance and fluidity. Preferably it is 78 / 22-93 / 7. The structural unit (IV) is substantially equimolar to the total of the structural units (II) and (III).

  On the other hand, when the structural unit (III) is not included, the structural unit (I) is preferably 40 to 90 mol% based on the total of the structural units (I) and (II) from the viewpoint of fluidity. 60 to 88 mol% is particularly preferable. The structural unit (IV) is substantially equimolar with the structural unit (II).

  In the above, “substantially equimolar” means that the unit constituting the polymer main chain excluding the terminal is equimolar of the dioxy unit and the dicarbonyl unit, but the unit constituting the terminal is not necessarily equimolar. Means not limited.

  In the polycondensation of the liquid crystalline polyester that can be preferably used in the present invention, in addition to the components constituting the structural units (I) to (IV), 3,3′-diphenyldicarboxylic acid, 2,2 ′ Aromatic dicarboxylic acids such as diphenyldicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid and dodecanedioic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, chlorohydroquinone, methylhydroquinone, 4, Aromatic diols such as 4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxybenzophenone, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4 -Cyclohexanediol, 1,4-cyclohexanedimethano In addition, an aliphatic hydroxycarboxylic acid such as an aliphatic alicyclic diol, m-hydroxybenzoic acid, 2,6-hydroxynaphthoic acid, etc. is added in a small proportion within a range where the effects of the present invention are not impaired. It can be copolymerized.

  Further, examples of the liquid crystalline polyester amide preferably include those obtained by copolymerizing p-aminophenol and / or p-aminobenzoic acid with the above preferred liquid crystalline polyester.

  The method for producing the liquid crystalline resin in the present invention is not particularly limited, and can be produced according to a known polyester polycondensation method.

  For example, in the production of the liquid crystalline polyester that is preferably used, when the structural unit (III) is not included, the production methods (1) and (2) below include the structural unit (III). ) Is preferable.

(1) Deacetic acid polycondensation reaction from diacylated products of aromatic dihydroxy compounds such as p-acetoxybenzoic acid and 4,4′-diacetoxybiphenyl, 4,4′-diacetoxybenzene, and aromatic dicarboxylic acids such as terephthalic acid A method for producing a liquid crystalline polyester.

(2) Acetic anhydride is reacted with p-hydroxybenzoic acid, aromatic dihydroxy compounds such as 4,4′-dihydroxybiphenyl and hydroquinone, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid to acylate phenolic hydroxyl groups. And then producing a liquid crystalline polyester by a deacetic acid polycondensation reaction.

(3) In the presence of a bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid such as a polyester polymer such as polyethylene terephthalate, an oligomer, or bis (β-hydroxyethyl) terephthalate, by the method of (1) or (2) A method for producing a liquid crystalline polyester.

  Although these polycondensation reactions proceed even without a catalyst, it is sometimes preferable to add a metal compound such as stannous acetate, tetrabutyl titanate, potassium acetate and sodium acetate, antimony trioxide, and metal magnesium.

  Some of the liquid crystalline resins in the present invention can measure logarithmic viscosity in pentafluorophenol. In this case, the value measured at 60 ° C. at a concentration of 0.1 g / dl is 0.5 dl / g. In particular, when the structural unit (III) is included, 1.0 to 3.0 dl / g is preferable, and when the structural unit (III) is not included, 2.0 to 10.0 dl / g is preferable.

  In addition, the melt viscosity of the (A) liquid crystalline resin in the present invention is preferably 1 to 2,000 Pa · s, and more preferably 2 to 1,000 Pa · s.

  In addition, said melt viscosity is the value measured with the Koka flow tester on condition of melting | fusing speed | rate (Tm) +10 degreeC of liquid crystalline resin, and the conditions of a shear rate of 1,000 / sec.

Here, the melting point (Tm) is a temperature of (Tm ₁ +20) ° C. after observing the endothermic peak temperature Tm ₁ observed when the polymer is measured by differential calorimetry at room temperature to 20 ° C./min. The endothermic peak temperature observed when the sample is cooled to room temperature under a temperature-decreasing condition of 20 ° C./min, and then measured again under a temperature-raising condition of 20 ° C./min. Point to.

  The fibrous filler used in the present invention is preferably glass fiber. Specifically, for example, a long fiber type or short fiber type chopped strand, milled fiber, or the like can be used.

  The number average fiber diameter of the fibrous filler used in the present invention is preferably 6 to 20 μm, particularly preferably 6 to 12 μm. The number average fiber length is more preferably 55 to 1000 μm, and even more preferably 55 to 700 μm. Use of glass fibers having a number average fiber diameter of 20 μm or more used in the present invention is not preferable because the thin-wall moldability is lowered. In addition, the number average fiber length of glass fibers used in the present invention is 1000 μm or less, so that the flowability during molding does not decrease, and the number average fiber length of glass fibers is 55 μm or more. Is preferable because the rigidity and toughness of the obtained molded product can be increased. Here, as a method for measuring the number average fiber diameter and the number average fiber length of glass fibers, 10 g of pellets made of a composition containing a liquid crystalline resin and glass fibers are heated in air at 550 ° C. for 8 hours to obtain a resin. The number average fiber diameter and the number average fiber length were calculated from those obtained by measuring arbitrary 500 long diameters and fiber lengths of the fibrous filler that had been removed using an optical microscope at a magnification of 120 times.

  Furthermore, in order to maximize the characteristics of the fibrous filler used in the present invention, it is important to blend 20 to 90 parts by weight with respect to 100 parts by weight of the liquid crystalline resin, more preferably 30 to 70 parts. Part by weight is used. It is preferable to blend 20 parts by weight or more of the fibrous filler because the injection molding process is stabilized. In addition, it is preferable that the blending amount of the fibrous filler is 100 parts by weight or less without inhibiting thin-wall formability.

  In the liquid crystalline resin composition used in the present invention, an antioxidant and a heat stabilizer (for example, hindered phenol, hydroquinone, phosphites, and substituted products thereof, etc., are within a range that does not impair the effects of the present invention. ), Ultraviolet absorbers (for example, resorcinol, salicylate, benzotriazole, benzophenone, etc.), mold release agents (such as montanic acid and salts thereof, esters thereof, half esters thereof, stearyl alcohol, stearamide and polyethylene wax), plasticizers, flame retardants Ordinary additives such as flame retardant aids and other thermoplastic resins (such as fluororesins) can be added to impart predetermined characteristics. In this case, since impurities such as low oligomer components are not preferred, attention should be paid to the type and amount added.

  The liquid crystalline resin composition used in 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, the liquid crystalline resin composition of the present invention is preferably an extruder, more preferably a twin-screw extruder, and more preferably an intermediate because of the necessity of kneading the reinforcing material uniformly with good dispersibility. It is particularly preferable to use a twin screw extruder having an addition port. In the melt kneading method, the liquid crystalline resin is supplied from the raw material supply port to the twin screw extruder, the liquid crystalline resin is melted, and the molten liquid crystalline resin and the fibrous filler is supplied from the intermediate addition port. preferable.

  The gate cross-sectional shape in the present invention is preferably a regular n-square shape or a circular shape with n = 5 or more. In the regular polygonal gate cross-sectional shape having apexes less than n, the resin pressure is not transmitted uniformly, voids are formed, air is easily trapped, and strength is easily reduced.

  In addition, if the gate size in the present invention is a regular polygon, the length of the longest diagonal line is preferably 3 to 0.5 mm, or if it is circular, the diameter is preferably 3 to 0.5 mm. 1 mm is more preferable. If the diameter is larger than the above range, the amount of discarded resin such as a runner increases, and further, jetting may occur and the strength may be reduced, which is not preferable. On the other hand, if the diameter is smaller than the above range, the pressure loss at the gate portion becomes large and molding becomes difficult.

  Further, the maximum thickness of the L-shaped molded product in the present invention is preferably 5 to 0.3 mm, more preferably 3 to 0.5 mm. If it is thicker than the above-mentioned thickness, even if the gate position is set at a distance of 10 mm or more from the bent portion, jetting may occur inside the molded product to cause a decrease in strength, which is not preferable. On the other hand, if the thickness is smaller than the above-mentioned thickness, it is difficult to fill by general injection molding.

  The liquid crystalline resin composition of the present invention can be used without limitation for applications such as electricity, electronics, automobiles, machinery, and miscellaneous goods, but can be preferably used for motor insulators of motors such as air conditioners and refrigerators.

[Method for producing liquid crystalline resin]
Reference example 1
870 parts by weight of p-hydroxybenzoic acid, 327 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 1367 parts by weight of acetic anhydride (1. 03 equivalents) was charged into a reaction vessel equipped with a stirring blade and a distillation tube, and reacted for 2 hours while raising the temperature from room temperature to 145 ° C. with stirring in a nitrogen gas atmosphere, from 145 ° C. to 320 ° C. in 4 hours. The temperature rose. Thereafter, the polymerization temperature was reduced to 133 Pa at 320 ° C. for 1.0 hour, and the mixture was further stirred for about 1.5 hours to perform polycondensation. The p-oxybenzoate unit is 70 molar equivalents relative to the sum of the p-oxybenzoate unit, 4,4′-dioxybiphenyl unit and 1,4-dioxybenzene unit, and 4,4′-dioxybiphenyl unit is 4 Melting point 314 ° C., melting point of 70 molar equivalents relative to the total of 4,4′-dioxybiphenyl units and 1,4-dioxybenzene units, 65 molar equivalents of terephthalate units relative to the total of terephthalate units and isophthalate units A liquid crystalline polyester (A1) having a viscosity of 25 Pa · s (324 ° C., orifice 0.5 mm diameter × 10 mm, shear rate 1,000 / sec) was obtained.

Examples 1-3, Comparative Examples 1-4
EXAMPLES Hereinafter, although an Example demonstrates this invention further in full detail, this invention is not limited to these.

  In Reference Example 1 using a twin-screw extruder (TEX-44 manufactured by Nippon Steel Works) with an intermediate addition port with a diameter of 44 mm, in which the cylinder set temperature was set to the melting point of the liquid crystalline resin + 10 ° C. and the screw rotation speed was set to 250 rpm. 100 parts by weight of the obtained liquid crystalline resin was added from the raw material supply port to obtain a molten state, and glass fibers were supplied from the intermediate addition port at a rate shown in Table 1, and melt-kneaded at a discharge rate of 40 kg / hour to obtain pellets. . The following properties were evaluated using this pellet. In addition, the measurement and test of the physical property in an Example were performed with the following method. Moreover, the average fiber length of glass fiber was measured with the following method using the pellet obtained by melt-kneading. The results are shown in Table 1.

In addition, as a fibrous filler, the following (B1, B2) were used, respectively.
B1: Chopped glass fiber (NEC Electric Glass ECS03T-779H average fiber diameter 10.5 μm, length 3 mm)
B2: Chopped glass fiber (ECS03T-790DE average fiber diameter 6.5 μm, length 3 mm manufactured by Nippon Electric Glass)

Measuring method of glass fiber length As a measuring method of the number average fiber diameter and the number average fiber length of glass fiber, 10 g of a pellet made of a composition containing a liquid crystalline resin and glass fiber is heated in air at 550 ° C. for 8 hours. The number average fiber diameter and the number average fiber length are calculated from the measured lengths and lengths of any 500 fibrous fillers using an optical microscope at 120 times magnification. did.

Characteristic measurement method (1) Bending strength ・ Molding: Pellet was subjected to FANUCROBOSHOTα-30i injection molding machine (manufactured by FANUC CORPORATION), injection speed 200 mm / second, injection pressure 20 MPa, cylinder setting temperature was the melting point of liquid crystalline resin Continuous molding (injection time / cooling time = 7.0 / 10.0 seconds, screw rotation speed 100 rpm, back pressure 1 MPa, suck back 10 mm, mold temperature 90 ° C.) under conditions, gate (circular, diameter 1 mm) position The L-shaped molded product (longitudinal length 90 mm, vertical length 30 mm, width 17 mm, thickness 3 mm) was formed.

  In the tensile test, the test piece schematically shown in FIG. 1 was used, and then the longitudinal direction of the test piece was directly fixed with a chuck using a tensile tester (AG500C, trademark, manufactured by Shimadzu Corporation), and perpendicular to the longitudinal direction. The direction portion was fixed with a wire and fixed with the other chuck (distance between chucks: 80 mm), pulled at a crosshead speed of 1 mm / min, and the load when the bent portion was broken was measured. Those having a bending portion strength of 500 N or more were evaluated as “excellent” (indicated by “◎”), and those having a bending portion strength of less than “N” (indicated by “×”). In FIG. 1, (a) is a side view, (b) is a front view, h is the distance from the bent portion to the gate, and the first to third embodiments are 10 mm. Comparative Example 1 was 5 mm, and Comparative Examples 2 to 4 were 8 mm.

  From the above results, the L-shaped molded product made of the liquid crystalline resin composition of the present invention draws out the flexural strength originally exhibited by the liquid crystalline resin composition as compared with the molded product of the comparative example having the same composition. You can see that

  The L-shaped molded product comprising the liquid crystalline resin composition of the present invention can bring out the potential rigidity while maintaining the original excellent heat resistance and fluidity of the liquid crystalline resin. It can be suitably used for a suitably used component, particularly an electric / electronic component, specifically, a motor insulator of an electric motor.

FIG. 1 is a schematic view of a test piece used when measuring the strength of a bent portion in the examples, with the surface on which the gate G is provided as a front position, (a) is a side view, and (b) is a front view. is there.

Explanation of symbols

G Gate position h Distance from bend to gate

Claims (5)

  When manufacturing an L-shaped molded product comprising a liquid crystalline resin composition containing 20 to 90 parts by weight of a fibrous filler with respect to 100 parts by weight of the liquid crystalline resin, 10 mm from the L-shaped bent portion. A method for producing an L-shaped molded article comprising a liquid crystalline resin composition, wherein a gate position is provided at a portion apart from the above, and injection molding is performed.   The method for producing an L-shaped molded article made of a liquid crystalline resin composition according to claim 1, wherein the fibrous filler is made of glass fibers having a number average fiber diameter of 6 µm to 20 µm.   3. The method for producing an L-shaped molded article comprising a liquid crystalline resin composition according to claim 1, wherein the gate cross-sectional shape is a regular n-square shape or a circular shape with n = 5 or more.   The gate cross-sectional shape is a regular n-corner shape or circle shape with n = 5 or more, and the length of the longest diagonal line of the regular n-corner shape or the diameter of the circle shape is a gate size of 3 mm or less. The manufacturing method of the L-shaped molded article which consists of a liquid crystalline resin composition of Claim 3 characterized by the above-mentioned.   The method for producing an L-shaped molded article comprising the liquid crystalline resin composition according to any one of claims 1 to 4, wherein the molded article to be molded has a maximum thickness of 5 mm or less.

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