JPH0214246A - Thermoplastic liquid crystal polymer composition and production thereof - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic liquid crystal polymer composition having improved impact resistance and long-term heat-resistance by compounding a specific amount of a specific potassium 6-titanate fiber. CONSTITUTION:The objective composition is produced by compounding (A) a thermoplastic liquid crystal polymer having a weight-average molecular weight of 5,000-200,000 [e.g., wholly aromatic (co)polyester or wholly aromatic (co) polyester amide] with (B) 5-60wt.% of potassium titanate fiber having a pH of 6-8, preferably 6.5-7.5, exhibiting a half-value width of <=0.1, preferably <=0.05 in a characteristic peak of an X-ray diffraction chart at 2theta=13.8 deg. and optionally surface-treated with at least one kind of compound selected from gamma-mercapto- propyl trimethoxysilane, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermotropic liquid crystal polymer composition and a method for producing the same.

Conventional technology and its problems Thermotropic liquid crystal polymers are easily oriented during molding due to their molecular structure (rigid linear molecules) even when used as a resin alone, and have high mechanical strength in the flow direction and low fluidity. It is attracting attention as a thermoplastic resin that has excellent properties such as excellent molding shrinkage in the flow direction and extremely low molding shrinkage in the machine direction, and is expected to be used in a variety of fields.

However, in such thermotropic liquid crystal polymers, because the polymer chains are easily oriented during molding, there is a large difference in strength and molding shrinkage in the flow direction and in the direction perpendicular to the flow direction (hereinafter referred to as "anisotropy"). As a result, it has become difficult to design the shape of molded products, narrowing the field of application.

In addition, in many application fields, materials are required that maintain the characteristics of the polymer, such as flame retardancy, chemical resistance, and moldability, while also having excellent heat resistance, various mechanical strengths, and rigidity. That is the reality.

Therefore, in recent years, attempts have been made to improve the anisotropy of the polymer by adding powdered or flaky fillers such as calcium carbonate, mica, and glass peas to the polymer, and to add fibrous reinforcement such as glass fiber to the polymer. Attempts have been made to improve the heat resistance, strength and stiffness of the polymer by incorporating agents into it. However, the former approach has the fatal drawback of significantly reducing the impact resistance of the polymer and making it extremely brittle, while the latter approach has the effect of improving the anisotropy of the polymer. In addition, it causes abrasion of the contact surface with processing machines and molds, and the appearance of embossed glass fiber patterns on the surface of the molded product, impairing the surface smoothness that is characteristic of liquid crystal polymers and worsening the appearance. This results in a serious drawback.

From this point of view, we aim to improve the heat resistance, strength and rigidity of thermotropic liquid crystal polymers, maintain good surface appearance, have low anisotropy, and reduce wear on molding machines and molds. Polymer compositions have been developed (see, for example, JP-A-61-195156, JP-A-62-81448, etc.). The former composition consists of fully aromatic copolyester, which is a type of thermotropic liquid crystal polymer, potassium titanate fiber (hereinafter referred to as rPTW), which is a microfiber;
In particular, it is a composition containing 5 to 70% by weight of PTW containing 0.025% or less of free potassium. In addition, the latter composition contains 5 to 7 PTW in a thermotropic liquid crystal polymer.
This is a composition containing 0% by weight.

However, these compositions have particularly low notched isot impact strength (i.e., poor impact resistance);
They have a fatal drawback of being brittle, and the latter composition in particular has poor long-term heat resistance, and there is currently a strong desire to resolve these drawbacks.

Means for Solving the Problems It is an object of the present invention to provide thermotropic liquid crystal polymer resin compositions and thermotropic liquid crystal polymer resin compositions that have significantly improved impact resistance and long-term heat resistance that could never be expected with conventional PTW reinforced materials. The object of the present invention is to provide a manufacturing method thereof.

That is, in the present invention, pH 6 to 8, X-ray diffraction chart 2θ=
The present invention relates to a thermotropic liquid crystal polymer composition characterized by containing 5 to 60 times % of 6-potassium titanate fibers having a half value width of 0.1 or less at a characteristic peak of 13.8 degrees.

In the present invention, thermotropic liquid crystal polymer is
A polymer that is liquid crystalline (molecules aligned in the same direction) in a molten state. As the thermotropic liquid crystal polymer used in the present invention, a wide variety of conventionally known thermotropic liquid crystal polymers can be used, such as wholly aromatic (co)polyester, wholly aromatic (co)polyester,
Co) Polyesteramides, aromatic-aliphatic copolyesters, aromatic polyazomethines, aromatic polyester carbonates, etc. may be mentioned, and these may be used alone or in a mixture of two or more.

Totally aromatic (co)polyester and wholly aromatic (co)polyester amide are called fully aromatic because each monomer component that makes up the polymer chain has at least one aromatic ring, and the molecular structure is Due to its rigidity, the polymer can exhibit liquid properties in the molten phase. Such monomer components include hydroquinone, resorcinol, 4.4'-dihydroxydiphenyl, 4.4'
Aromatic aromas such as dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfone, 2,6-dihydroxynaphthoyl, etc. group diol, p-phenylenediamine, m-phenylenediamine,
p-xylylene diamine, m-xylylene diamine, 4
, 4'-diaminodiphenyl, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane,
Aromatic diamines such as 4,4'-diaminobenzophenone, 4°4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, terephthalic acid, isophthalic acid, 4,4'-dicarboxydiphenyl, 4.4 '
- Aromatic dicarboxylic acids such as dicarboxydiphenyl ether and 2,6-dicarboxynaphthoyl; aromatic acids such as p-hydroxybenzoic acid, m-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-hydroxycinnamic acid; Examples include aromatic aminocarboxylic acids such as hydroxycarboxylic acid, p-aminobenzoic acid, and 6-amino-2-naphthoic acid, but are not limited thereto.

A wholly aromatic (co)polyester and a wholly aromatic (co)polyester amide can be easily produced from these monomer components according to conventional methods. Fully aromatic (co)polyesters are disclosed in, for example, JP-A-56-104932 and JP-A-57-44.
According to the method disclosed in US Pat.
Each is manufactured according to the method disclosed in No. 82842.

A specific example of the aromatic-aliphatic (co)polyester is a copolymer of polyethylene terephthalate and p-hydroxybenzoic acid.

Specific examples of the aromatic polyazomethine include polytrilow 2-methyl-1,4-phenylenenitrilomethylidine-1,4-phenylenemethylidine), polytrilow 2-methyl-1,4-phenylenenitrilomethylidine-1,4-phenylenemethylidine)
-Methyl-1,4-phenylenenitrilomethylidine-1
, 4-phenylene methylidine), polytrilow 2-chloro-1,4-phenylene nitrilomethylidine-1,4
(phenylene methylidine), etc.

As the aromatic polyester carbonate, those disclosed in, for example, US Pat. No. 4,107,143 and US Pat. No. 4,284,757 are widely used.

The thermotropic liquid crystal polymer used in the present invention is
The weight average molecular weight measured by gel permeation chromatography is about 5,000 to about 200,000, especially about 10,000 to about 5
Preferably, it is 10,000.

If the weight average molecular weight of the thermotropic liquid crystal polymer is too small, the mechanical properties of the resulting resin composition tend to deteriorate; on the other hand, if the weight average molecular weight of the polymer is too large, it is difficult to produce such a polymer, and Both are unfavorable since the melt viscosity of the polymer increases, which tends to make the resulting resin composition difficult to mold.

The potassium titanate fibers blended into the composition of the present invention are:
It has the chemical formula K2O.6TiO□, and p)I is 6 to 8.
, preferably 6.5 to 7.5, and the half width at the characteristic peak at 2θ = 13.8° in the X-ray diffraction chart is 0.1.
Hereinafter, highly crystalline potassium 6-titanate fiber (6-PTW) with a particle size of 0.05 or less is preferred. What is pH here?
1% by weight suspension of PTW in water (using deionized water)
This refers to the value measured at 20°C after stirring for a minute. In addition, the half-width at the characteristic peak at 2θ = 13.8° in the X-ray diffraction chart means the peak height at 2θ = 13.8' by H11/
When the peak width at 2H is W, it is a value expressed as W/H. The latter value is an index indicating the degree of crystallinity of PTW, and the smaller the half width, the greater the degree of crystallinity.

The 6-PTW having the above characteristic values used in the present invention is
For example, it is manufactured according to the method shown below.

That is, 20 components such as 2CO3 and TiO2 are added to K2O1.
, 6-P TW is produced from Ti02 components such as TiO2-containing compounds according to conventionally known methods such as hydrothermal method, flux method, calcination method, melting method, etc., and then heat-treated at a high temperature of 700 ° C. or higher. After that, the characteristic peak at 2θ = 13.8° is highly crystallized with a half width of 0.1 or less, preferably 0.05 or less, and then acid treatment and water washing make the crystal system (6
-PTW) can be adjusted to a so-called neutral range of slightly acidic to slightly alkaline pH of 6 to 8 without changing 6-PTW.

When the pH of the 6-P TW used in the present invention exceeds 8, the thermotropic liquid crystal polymer easily undergoes molecular chain scission (thermal decomposition) during thermal melting (during blending and kneading and molding), resulting in molded products. The mechanical strength, especially the Izot impact strength, is significantly reduced, making it impossible to achieve the intended purpose of the present invention. On the other hand, when the pH is less than 6, 6-P TW
This is inconvenient because the acid remaining in the molded product not only deteriorates in appearance and mechanical strength but also causes corrosion of processing machines and molds.

Further, the half width of 6-PTW used in the present invention is 0.
If the pH exceeds 1, even if the pH is adjusted to 8 or less by acid treatment during the synthesis stage of 5-P TW, the crystallinity will be low and the pH will be lower than 6.
-The 20 component in PTW easily migrates to the surface of 6-PTW, and therefore, when kneaded into a thermotropic liquid crystal polymer, it is dissolved in the trace amount of water contained in the polymer, and the p
It is unsuitable because it becomes alkaline with H exceeding 8, and as a result, the molecular chains of the polymer are hydrolyzed at high temperatures where several polymers are melted, and therefore the reinforcing effect of 6-P TW cannot be fully expressed. be.

If 6-P TW with the above characteristic values is used, the reinforcing effect will be greater than that of high dimension glass fibers, which were conventionally considered to have a large reinforcing effect. Although the product is GF reinforced, its Izotsu impact value is significantly inferior and it is brittle.
It was discovered that this result overturns the chemical common sense.

The fiber diameter and fiber length of 6-P TW used in the present invention are not particularly limited, but the fiber diameter is usually 0.
The fiber length is usually about 0.01 to 2 μm, preferably about 0.05 to 1 μm, and the fiber length is usually about 2 to 500 μm, preferably 5
~100μm, aspect ratio (fiber length/fiber diameter)
It is appropriate that the value is 10 or more.

The 6-PTW used in the present invention does not need to be treated with a surface treatment agent, but is preferably surface treated with a surface treatment agent. As such a surface treatment agent, γ
-Mercaptopropyltrimethoxysilane, β-(3,
At least one selected from the group consisting of 4-epoxycyclohexyl)ethyltrimethoxysilane and N-phenyl-γ-aminopropyltrimethoxysilane is preferred. The use of 6-PTW treated with such a surface treatment agent has the advantage that it can be easily fed to a melt mixer which is carried out later.

In the present invention, the blending amount of the 6-PTW is 5 to 60% by weight, preferably 10% by weight, based on the total amount of the thermotropic liquid crystal polymer and the 6-PTW.
It is preferable that the amount is about 50% by weight. 6-P
If the blending amount of TW is less than 5 times %, the mechanical strength and rigidity (flexural modulus) of the resulting composition will not be sufficiently improved. On the other hand, when the amount of 6-P TW exceeds 60% by weight, 6-P TW itself becomes very bulky (
Apparent density 0.05~0. 2g/ee), which makes it difficult to feed to a melt mixer, which is not practical.

The thermotropic liquid crystal polymer composition of the present invention contains antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, mold release agents, colorants such as pigments, and flame retardants, within the range that does not impair the purpose of the present invention. , flame retardant aids, antistatic agents, conductivity imparting agents such as Ketchen Black, fillers in the form of powders such as calcium carbonate or flakes such as mica, reinforcing materials such as glass fibers and carbon fibers, etc., as appropriate. It can also be blended.

In producing the composition of the present invention, the blending means is not particularly limited, and the thermotropic liquid crystal polymer and 6. -P
TW may be premixed in advance using a Henschel mixer, tumbler mixer, or the like, or each may be separately supplied to a melt mixer and melt-kneaded. In particular, in order to produce uniformly shaped pellets with good quantitative properties for a molding machine such as an injection molding machine, it is preferable to follow a rotary type mist cutting method. In this method, a thermotropic liquid crystal polymer and 6-PTW are uniformly mixed in a melt mixer and then pelletized in a mist cut pelletizer. More specifically, the liquid crystal polymer and 6-P
After uniformly melting and kneading TW with a melt mixer, a rotary cutter that rotates at high speed is arranged perpendicular to the die section that extrudes it into a strand shape, and water and air are mixed from a nozzle provided at one end. Hot cutting can be performed with the cutting chamber filled with mist. According to the research of the present inventor, the melted material is first collected in the form of a strand using a conventional method, and after cooling in a water tank,
Even if the thermotropic liquid crystal polymer is pelletized using a general pelletizer, even if shearing force is applied to the completely solidified state where the thermotropic liquid crystal polymer crystallizes in the extrusion direction, the strands will break and become crumb-like, which is not the case with ordinary thermoplastic resins. It was difficult to produce pellets such as those obtained in

Effects of the Invention According to the present invention, a thermotropic liquid crystal polymer resin composition is provided, which has significantly improved impact resistance and long-term heat resistance, which could never be expected with conventional PTW reinforced materials. Moreover, the composition of the present invention improves the heat resistance, strength, and rigidity of the thermotropic liquid crystal polymer, maintains a good surface appearance, has small anisotropy, and
There is less wear on the molding machine and mold.

Example Examples are given below to further clarify the present invention.

Examples 1 to 3 Fully aromatic polyester Vectra A950 [manufactured by Hoechst Celanese] was used as a thermotropic liquid crystal polymer.

In addition, as potassium titanate fiber, 6-PTW (average fiber diameter 0.3 μm,
An average fiber length of 15 μm] was used. Furthermore, this 6-PTW
In order to improve the supply of potassium titanate fibers and the wettability with the thermotropic liquid crystal polymer, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane was added to 6-P TW heavy weight. Surface treated by adding 1% by weight (pH value after surface treatment is 7.1)
.

Vectra A950 and 6-P TW were heated in a twin screw extruder (PCM
45, manufactured by Ikegai Tekko ■] from the main hopper and side feeder, and after melting and kneading at a cylinder temperature of 300°C, the mist cut pelletizer [PHR-
100, manufactured by Ikegai Tekko ■] at a circulating oil temperature of 320° C., and then dehydrated and dried to obtain a uniform bean-like egg white pellet.

The obtained pellets were injection molded using an injection molding machine [FS-15ON, manufactured by Nisshin Jushi Kogyo ■] at a cylinder temperature of 290°C and a mold temperature of 80°C to obtain each test piece.

The tensile properties, bending properties, isot impact strength (notched), and heat distortion temperature were determined according to ASTM D-638, D, respectively.
-790, D-256, and D-648. In addition, the color difference ΔE between the test piece after being retained in an injection molding machine with a cylinder temperature of 290°C for 15 minutes and the test piece before being retained was measured using a colorimeter [Model Z-1001DP, manufactured by Nippon Heavy Industries Ltd.].
The thermal stability of the test pieces obtained in each example was evaluated.

These results are shown in Table 1 below.

Comparative Examples 1 to 3 and Reference Example 1 In Comparative Example 1, Vectra A950 was injection molded as it was. In Comparative Examples 2 and 3, in the same manner as in Examples 1 to 3, Vectra A950 and potassium titanate fibers shown below were melt-kneaded at a ratio of 70:30 (weight ratio), pelletized, and subjected to the same injection process. A molded test piece was obtained.

Potassium titanate fiber used in Comparative Example 2: pH 9,
2. X-ray diffraction chart 6-PTW (fiber diameter and fiber length are the same as those of Examples 1 to 3) with a half-value width of 0.113 at the characteristic peak of 2θ = L3.8', and Surface treated with the same silane coupling agent as 1 to 3 (pH value after surface treatment is 9)
．． 8).

Potassium titanate fiber used in Comparative Example 3: JP-A-6
HT-200 (described in Publication No. 1-19515)
Average fiber diameter 0.45 μm 1 average fiber length 22.5 μm, p
H8,2, 6-P TW with half width 0.03,
Surface treated with the same silane coupling agent as in Examples 1 to 3 (pH value after surface treatment is 8.5).

The same physical properties as in the above examples were measured for each injection molded test piece of Comparative Examples 1 to 3.

For reference, commercially available pellets filled with 30% glass fiber [Vectra A-130, manufactured by Polyplastics]
was injection molded in the same manner as above, and the same physical properties were measured.

The results are also shown in Table 1 below.

From Table 1 above, the following is clear. That is, the molded article of Example 2 exhibits higher mechanical strength than those of Comparative Examples 2 and 3. In particular, the notched isot impact strength is amazingly 10 times higher than that of conventionally known PTW reinforced products, and it also has more than double the high impact strength compared to the glass fiber reinforced product of Reference Example 1. There is.

Example 4 Aromatic-aliphatic polyester Rodlan LC500 (manufactured by Unitika) as a thermotropic liquid crystal polymer
It was used.

Moreover, the same potassium titanate fibers as in Examples 1 to 3 were used.

Rodlan LC500 and 6-PTW were mixed at a ratio of 70=30 (weight ratio) to obtain pellets in the same manner as in Examples 1 to 3. Next, injection molded test pieces were prepared from the pellets and physical properties were evaluated.

Comparative Example 4 An injection molded test piece was obtained in the same manner as in Example 4, except that the potassium titanate fiber used in Comparative Example 2 was used as the potassium titanate fiber, and the physical properties were evaluated.

Various physical properties of the test piece of Example 4 and the test piece of Comparative Example 4 are shown below.

The above results show that when the 6-P TW of the present invention is used, the resulting molded product has high mechanical properties, high Izot impact strength, and less thermal discoloration due to retention during molding.

Claims (4)

[Claims] (1) A thermotropic product characterized by containing 5 to 60% by weight of 6-potassium titanate fibers with a pH of 6 to 8 and a characteristic peak at 2θ = 13.8° in an X-ray diffraction chart whose half-width is 0.1 or less. Liquid crystal polymer composition. (2) Potassium titanate fiber has a pH of 6.5 to 7.5,
2. The composition according to claim 1, wherein the half-width at a characteristic peak at 2θ=13.8° in a line diffraction chart is 0.05 or less. (3) The surface of the potassium titanate fiber was selected from the group consisting of γ-mercaptopropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane. Claims treated with at least one type of claim (1)
) or the composition described in (2). (4) A thermotropic liquid crystal polymer characterized in that the 6-potassium titanate fiber and the thermotropic liquid crystal polymer according to claim (1) are uniformly melt-kneaded using a melt mixer and then pelletized using a mist cut pelletizer. Method for producing the composition.