JP3538950B2 - Liquid crystal polyester resin mixture and molding method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal polyester which can stably plasticize a liquid crystal polyester at the time of molding and can provide a stable molding, and provides a molded article having excellent mechanical properties and thermal stability. The present invention relates to a resin mixture and a method for molding a liquid crystal polyester using the liquid crystal polyester resin mixture.

[0002]

2. Description of the Related Art Liquid crystal polyesters form a polydomain having a liquid crystal state without entanglement even in a molten state because molecules are rigid, and exhibit a behavior in which molecular chains are remarkably oriented in a flow direction at a low shear rate. It is called a type (thermotropic liquid crystal) polymer. Liquid crystal polyesters have extremely excellent melt fluidity due to this specific behavior, and have heat deformation resistance of 300 ° C. or more depending on the structure, and molded articles for use in electronic components, OA, AV components, heat-resistant tableware, etc. It is used for

[0003] As a molding method for obtaining these molded articles,
It is common to use an extruder using a screw such as injection molding or extrusion molding. At this time, the instability in the plasticizing process of the liquid crystal polyester is often considered to be a problem. That is, the plasticization time is not constant and becomes unstable, and in injection molding, plasticization may not be completed within the cooling time. In some cases, the quality was also adversely affected.

The reason why the plasticization time of the liquid crystal polyester becomes unstable is not clear, but one of the causes is that the melt viscosity of the liquid crystal polyester itself is largely dependent on the shear rate and the temperature, and therefore, the particles of the liquid crystal polyester It is mentioned that only the surface is selectively plasticized and the fusion is likely to occur.

As means for suppressing such a phenomenon, Japanese Patent Application Laid-Open No. 5-125259 discloses the use of a composition obtained by blending a higher fatty acid metal salt and a higher fatty acid with a thermotropic liquid crystal polymer. ing.
JP-A-5-125258 discloses that plasticization can be stably performed by using a particle mixture comprising thermotropic liquid crystal polymer particles and a metal salt of a higher fatty acid.

However, in each case, since a higher fatty acid or a metal salt thereof which decomposes at a high temperature is used in combination with a liquid crystal polymer having high heat resistance, a gaseous product in a molding machine is required to obtain a molded product of the liquid crystal polymer. It is not always sufficient for the purpose of higher practicality because it is difficult to carry out stable molding work because of increased generation, and there is a concern that the thermal stability of the obtained molded product may be reduced. is not.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above problems, whereby the resin mixture itself is plasticized stably during molding, stable molding can be performed, and mechanical properties and It is an object of the present invention to provide a liquid crystal polyester resin mixture which gives a molded article having excellent thermal stability and a method for molding a liquid crystal polyester using the liquid crystal polyester resin mixture.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a fluorocarbon-based liquid crystal polyester or a liquid crystal polyester resin composition containing a liquid crystal polyester and a filler as main components has been added. The present inventors have found that a liquid crystal polyester resin mixture which achieves the above object can be obtained by blending a specific amount of a surfactant, and that the liquid crystal polyester can be plasticized stably during molding by using the mixture.

That is, the present invention is the following invention. (1) 100 parts by weight of liquid crystal polyester and fillers 0 to 15
Liquid crystal polyester resin composition 1 containing 0 parts by weight as a main component
0.00 parts by weight of the fluorocarbon surfactant 0.00
A liquid crystal polyester resin mixture, wherein 1 to 5 parts by weight of the liquid crystal polyester resin composition is mixed at a temperature lower than a flowing temperature defined below. Flow temperature: 4
Load the resin heated at a heating rate of 100 ° C / min with a load of 100 kgf.
This is a temperature at which the melt viscosity shows 48,000 poise when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under the pressure of / cm ² . (2) liquid crystal polyester are those containing 30 mol% of the total at least a repeating structural unit represented by the formula A ₁ (1) below the liquid crystal polyester resin mixture according.

[0010]

Embedded image (3) A method for molding a liquid crystal polyester, comprising using the liquid crystal polyester resin mixture according to (1) or (2).

The liquid crystal polyester used in the present invention is:
A polyester called a thermotropic liquid crystal polymer, which is derived from (1) a combination of an aromatic dicarboxylic acid, an aromatic diol, and an aromatic hydroxycarboxylic acid, and (2) a polyester derived from a different kind of aromatic hydroxycarboxylic acid. And (3) a product derived from a combination of an aromatic dicarboxylic acid and an aromatic diol, and (4) a product obtained by reacting an aromatic hydroxycarboxylic acid with a polyester such as polyethylene terephthalate. To form an anisotropic melt at a temperature of In addition, instead of these aromatic dicarboxylic acids, aromatic diols and aromatic hydroxycarboxylic acids,
Sometimes their ester-forming derivatives are used.

Examples of the repeating structural unit of the liquid crystal polyester include, but are not limited to, the following. Repeating structural unit derived from aromatic hydroxycarboxylic acid:

[0013]

Embedded image Repeating structural unit derived from aromatic dicarboxylic acid:

[0014]

Embedded image Repeating structural unit derived from aromatic diol:

[0015]

Embedded image

[0016]

Embedded image

[0017] heat resistance, mechanical properties, particularly preferred liquid crystal polyesters of the balance between workability, the repeating structural unit represented by the formula A ₁ are those containing at least 30 mol%.

Specifically, the following combinations (a) to (f) are preferred. (A): (A ₁ ), (B ₁ ) or (B ₁ ) and (B ₂ )
A mixture of (C ₁ ). (B): (A ₁ ), (A ₂ ). (C) in those combinations of the structural units of :( a), that replaces the part of A ₁ in A _2. (D) In those combinations of the structural units of :( a), that replaces the part of B ₁ in B _3. (E) in what combination of structural units of :( a), that replaces the part of the C ₁ at C _3. (F): a combination of the structural units of (b) plus the structural units of B ₁ and C ₁ . The liquid crystal polyesters having the basic structures (a) and (b) are described, for example, in JP-B-47-47870, respectively.
And JP-B-63-3888.

In the present invention, a filler is added to the liquid crystal polyester as required. When adding filler,
150 parts by weight of filler for 100 parts by weight of liquid crystal polyester
The filler is added in an amount of 20 parts by weight or less, preferably 20 parts by weight to 100 parts by weight of the liquid crystal polyester. When the compounding ratio of the filler is more than 150 parts by weight, the melt viscosity of the composition increases, the granulating property and the moldability decrease, and even if a fluorocarbon surfactant is added to the liquid crystal polyester resin composition, In addition, the effect of stabilizing plasticization at the time of molding is reduced. The liquid crystal polyester resin composition used in the present invention is generally in the form of particles such as pellets or chips. The preferred shape of the liquid crystal polyester resin composition is a column or a sphere having an average particle diameter of 1 mm or more and 10 mm or less. If the average particle size is smaller than 1 mm, gas is liable to be entrained when plasticizing the resin with a screw during molding, and the surface condition of the obtained product is unfavorably deteriorated. In addition, the average particle size is 10
If it is larger than mm, plasticization during molding processing becomes difficult, and the rotational torque of the screw also increases, which is not preferable. Means for obtaining particles or chips of the liquid crystal polyester resin composition is not particularly limited, but a liquid crystal polyester and a filler, if necessary, a release improver, a heat stabilizer, a coloring material, etc. may be added to a Henschel mixer, a tumbler, or the like. After mixing using, extruder to perform melt kneading,
A method of cutting the molten resin extruded from the hole of the die into particles by a rotary blade, or a method of cutting the resin strand extruded from the hole of the die into particles by cooling and solidifying with a rotary blade is common. . It is also possible to obtain liquid crystal polyester particles or chips by directly connecting an extruder downstream of the reactor for the polymerized liquid crystal polyester.

The filler used in the present invention is a fibrous or needle-like reinforcing material such as glass fiber, silica alumina fiber, wollastonite, carbon fiber, potassium titanate whisker, aluminum borate whisker, and titanium oxide whisker. ; Calcium carbonate, dolomite, talc,
Examples include inorganic fillers such as mica, clay, and glass beads, and one or more of them can be used.

The fluorocarbon surfactant used in the present invention generally has a fluorocarbon group as a basic skeleton and a hydrophilic group added thereto. Generally,
A linear or branched perfluoroalkyl group (C _n F _{2n + 1} ) having 6 to 10 carbon atoms has a hydrophobic skeleton, and a sulfonate, a carboxylate, an ammonium salt as a hydrophilic group,
Aminosulfonic acid salts and the like are used.

The fluorocarbon surfactants preferably have a particle size of 80 mesh pass. Examples of commercially available products include Florad FC-95 and FC-95, which are potassium salts of perfluoroalkylsulfonic acid. 9
3 (manufactured by 3M), Megafac F-110 (manufactured by Dainippon Ink and Chemicals, Inc.), Florado FC-124 (manufactured by 3M), which is a lithium salt of trifluoromethanesulfonic acid, and highly branched perfluorocarbon Examples of the sulfonate include trade names “Fugent” 100 and 110 (manufactured by Neos).

In the liquid crystal polyester resin mixture of the present invention, the mixing ratio of the fluorocarbon surfactant is 0.001 to 5 per 100 parts by weight of the liquid crystal polyester or 100 parts by weight of the total of the liquid crystal polyester and the filler.
Parts by weight, and particularly preferably 0.003 to 3 parts by weight.
Parts by weight. When the mixing ratio of the fluorocarbon surfactant is more than 5 parts by weight, the plasticization time increases during molding and the variation in the plasticization time between shots increases. As a result, the molded product is colored, It is not preferable because the mechanical strength decreases and the amount of gas generated from the molded article increases. Also, when the compounding ratio of the fluorocarbon surfactant is less than 0.001 part by weight, the effect of stabilizing the plasticization at the time of the intended molding is insufficient, which is not preferable.

In the liquid crystal polyester resin mixture of the present invention, a compound having an external lubricant effect, such as a higher fatty acid, a metal salt of a higher fatty acid, a phosphorus compound, or a fluororesin powder, is mixed with the fluorocarbon surfactant in the liquid crystal polyester resin composition. It is also possible.

The liquid crystal polyester resin composition used in the present invention or the liquid crystal polyester resin mixture of the present invention is added to a colorant such as a dye or a pigment as long as the object of the present invention is not impaired; an antioxidant; One or more conventional additives such as an agent, an ultraviolet absorber, an antistatic agent, and a surfactant can be added. In addition, a small amount of thermoplastic resin, for example, polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether and modified products thereof, polysulfone, polyethersulfone, polyetherimide and the like, and a small amount of thermosetting resin, For example, one or two or more of phenol resin, epoxy resin, polyimide resin and the like can be added.

The liquid crystal polyester resin mixture of the present invention comprises
As long as the liquid crystal polyester or the liquid crystal polyester resin composition containing the liquid crystal polyester and the filler as main components and the fluorocarbon-based surfactant are mixed at a temperature lower than the flow temperature of the liquid crystal polyester, the compounding means is not particularly limited. For example, it can be obtained by mixing particles of a liquid crystal polyester resin composition and powder or particles of a fluorocarbon surfactant in a solid state at room temperature or in a heated atmosphere using a Henschel mixer, a tumbler or the like.

[0027]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. The measurements and tests of various physical properties in the examples were performed by the following methods. (1) Measurability at the time of injection molding: The average weighing time of 50 consecutive shots and its standard deviation were calculated. (2) Tensile properties: molded ASTM No. 4 tensile dumbbell,
It was measured in accordance with ASTM D638.

(3) Relative amount of low-boiling gas generated from the molded article: JIS 1 (1/2) dumbbell (0.8 m thick)
m), and the obtained molded product is 5 mm in length and 5 m in width.
m, and cut into chips having a thickness of 0.8 mm. This chip 4
g, precisely weighed, washed with distilled water, placed in a vacuum-dried 25 cc vial, sealed with a packing made of polytetrafluoroethylene, heated in a hot air dryer set at 120 ° C for 20 hours, and molded. Gas was evolved from the product. This vial was used for headspace gas chromatography (GC-15A / HSS-3) manufactured by Shimadzu Corporation.
A) Attach to A) and keep it at 120 ° C.
-WAX (manufactured by J & WS CIENTIFIC) was used to inject into a 15 m-long column, and at the same time as the injection, the column temperature was raised from 80 ° C. at 2 ° C./min, and the total amount of gas up to a retention time of 25 minutes was detected by a detector. . An FID type was used as a detector, and helium was used as a carrier gas.

The relative amount of this gas is represented by the total area of various gases, and the relative amount of gas generated from the molded article is compared with this value. If you did not put the sample in the vial,
That is, the measured value in an empty bottle is 3000, and the larger the value, the more low-boiling gas is generated from the molded product. Gases detected by the retention time of 25 minutes were analyzed by gas chromatography / mass spectrometry to find aromatic hydrocarbons,
It was confirmed to be aliphatic hydrocarbons, acetic acid, phenols and the like.

Examples 1-4, Comparative Examples 1-3 The repeating structural unit is A₁, B₁, B_Two, C₁From
A₁: B₁: B _Two: C₁Is 60:15:
5:20 and the flow temperature determined by the above method is 323 ° C.
Liquid crystal polyester and milled glass fiber (
Table 1 shows EFH75-01 manufactured by Central Glass Co., Ltd.
After mixing with a Henschel mixer with the composition, a twin screw extruder (Ikegai
Cylinder temperature using a PCM-30 manufactured by Tekko Co., Ltd.)
Granulated at a temperature of 340 ° C. to obtain a liquid crystal polyester resin composition.
Was. The obtained liquid crystal polyester resin composition is
Is also cylindrical with an average particle size of 2 mm and a length of 2.5 mm.
Was. The obtained liquid crystal polyester resin composition is
Florer, a potassium salt of fluoroalkylsulfonic acid
With FC-95 (3M) at the ratio shown in Table 1.
Mix at room temperature using a blur and mix with a liquid crystal polyester resin.
Compound was obtained.

These liquid crystal polyester resin mixtures were
After drying at 20 ° C. for 3 hours, JIS 1 (1/2) dumbbells were molded at a cylinder temperature of 350 ° C. and a mold temperature of 130 ° C. using an injection molding machine (PS40E5ASE manufactured by Nissei Plastics Industry Co., Ltd.). The weighing time of the shot was measured and its stability was evaluated. The tensile properties and the amount of generated gas were measured from the obtained dumbbell pieces. Similarly, for a liquid crystal polyester resin composition containing no fluorocarbon-based surfactant (Comparative Example 1), the stability of the measurement time,
The tensile properties and the amount of generated gas were measured. Table 1 shows the results.

The composition in which the phosphorus compound was mixed with the liquid crystal polyester resin composition (Examples 1 to 4) had less fluctuation in the measuring time between shots than the composition containing no phosphorus compound (Comparative Example 1). It can be seen that the measuring time itself is shortened, the plasticization is stable, the mechanical properties are excellent, and the gas generated from the molded product is at a low level.
In the case where the fluorocarbon surfactant was mixed with 0.0005 parts by weight of the liquid crystal polyester resin composition (Comparative Example 2), the effect of stably plasticizing during molding was insufficient. On the other hand, in the case of mixing 25 parts by weight of the fluorocarbon surfactant with respect to the liquid crystal polyester resin composition (Comparative Example 3), the molded product was discolored and the tensile properties were significantly reduced.

Comparative Example 4 An experiment was carried out in the same manner as in Example 1 except that a fluorocarbon surfactant was mixed with a liquid crystal polyester in advance together with milled glass fibers and granulated by a twin screw extruder. Table 1 shows the results. In the case where the fluorocarbon surfactant was previously kneaded into the liquid crystal polyester resin in a molten state (Comparative Example 4), the absolute value of the measuring time and the variation between shots were large, and the plasticization during molding was unstable.

Comparative Example 5 An experiment was conducted in the same manner as in Example 1 except that a sodium salt of 2-ethylhexylalkyl sulfate was used instead of the fluorocarbon surfactant. Table 1 shows the results. In the case where the sodium salt of 2-ethylhexylalkyl sulfate was mixed with the liquid crystal polyester resin (Comparative Example 5), the effect of stabilizing the plasticization was insufficient and the amount of gas generated from the molded product was extremely large.

[0035]

[Table 1]

[0036]

According to the liquid crystal polyester resin mixture of the present invention, a liquid crystal polyester is stably plasticized at the time of molding, a stable molding can be performed, and a molded article having excellent mechanical properties and thermal stability is obtained. Is a liquid crystal polyester resin mixture. The liquid crystal polyester molding method using the liquid crystal polyester resin mixture is useful in molding performed by an extruder using a screw such as injection molding and extrusion molding.

Continuation of the front page (56) References JP-A-6-207083 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 67/00-67/04

Claims (3)

(57) [Claims] 1. A liquid crystal polyester composition comprising 100 parts by weight of a liquid crystal polyester and 0 to 150 parts by weight of a filler, 100 parts by weight of a liquid crystal polyester resin, and 0.001 to 5 parts by weight of a fluorocarbon surfactant. A liquid crystal polyester resin mixture, which is mixed at a flow temperature of the resin composition defined below. Flow temperature: 4 ° C. / min heating rate in a heated resin under load 100 kgf / cm ^2, an inner diameter of 1 mm, length 10
mm when extruded from a 4 inch nozzle
This is the temperature that indicates poise. 2. A liquid crystal polyester is a liquid crystal polyester resin mixture according to claim 1, wherein those containing 30 mol% of the total at least a repeating structural unit represented by the formula A ₁ below. Embedded image 3. A method for molding a liquid crystal polyester, comprising using the liquid crystal polyester resin mixture according to claim 1.