JPH0323337B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a multilayer composite injection molded product having high heat resistance and excellent mechanical properties, especially a high elastic modulus even in a thick molded product. <Prior art> Liquid crystalline polyester forms an anisotropic melt phase,
It is known that highly oriented injection molded articles with high modulus of elasticity can be obtained without adding reinforcing materials such as glass fibers during injection molding. Examples of aromatic polyesters that form an anisotropic melt phase include liquid crystal polymers obtained by copolymerizing p-hydroxybenzoic acid with polyethylene terephthalate (Japanese Patent Application Laid-open No. 72393/1983), p-hydroxybenzoic acid and 6-hydroxy- Liquid crystal polymers made by copolymerizing 2-naphthoic acid (Japanese Unexamined Patent Publication No. 77691/1989), and liquid crystal polymers made by copolymerizing p-hydroxybenzoic acid with 4,4'-hydroxybiphenyl, terephthalic acid, and isophthalic acid (Special Publication No. 57-24407, Japanese Unexamined Patent Publication No. 60-25046) are known. <Problems to be Solved by the Invention> However, it is known that these liquid crystal polyesters can produce injection molded products with a high elastic modulus when the molded product is thin, but have a low elastic modulus when the molded product is thick ( WJJackson et al., J.Polym.Sci.
Polym.Chem.Ed., 14 , 2043 (1976)). The present inventors have previously discovered that multilayer composite molding is effective in obtaining a high elastic modulus molded product even when the molded product is thick, but many of these liquid crystal polyesters It was found that the properties were poor and a multilayer composite molded product with a high modulus of elasticity could not be obtained. Therefore, it is an object of the present invention to obtain a high elastic modulus multilayer composite injection molded product with high interlayer adhesive strength. <Means for Solving the Problems> As a result of intensive studies to solve the problems, the present inventors have arrived at the present invention. In other words, the present invention provides an anisotropic material, at least one of which is composed of a structural unit selected from the following structural formulas () to (), and which has a heat of crystal fusion of 0.1 cal/g or less as measured by a differential scanning calorimeter (DSC). The present invention relates to a multilayer composite injection molded article comprising one or more polymers which are aromatic polyesters capable of forming a molten phase. (However, X in the formula is

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Indicates one or more groups selected from [Formula], and Y is

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[expression] and

Indicates one or more groups selected from [Formula] vinegar. Also, Z is

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Indicates one or more groups selected from [Formula]. ) In the aromatic polyester capable of forming an anisotropic melt phase used in the present invention, the above structural unit ( )
is methylhydroquinone, chlorohydroquinone, phenylhydroquinone, t-butylhydroquinone, hydroquinone, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 2,6-dihydroxynaphthalene,
The structural unit () is a structural unit of a polyester produced from one or more dihydroxy compounds selected from 2,7-dihydroxynaphthalene and 4,4'-diphenyldicarboxylic acid, and the structural unit () is a structural unit formed from one or more dihydroxy compounds selected from the above. , 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, 1,2
-bis(2-chlorophenoxy)ethane-4,
4'-dicarboxylic acid, terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 4,4'-
diphenyl ether dicarboxylic acid and 1,4-
It shows the structural unit of polyester produced from one or more dicarboxylic acids selected from cyclohexanedicarboxylic acids. Moreover, the structural unit () is p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 3-chloro-4-hydroxybenzoic acid, 3-hydroxybenzoic acid,
It shows the structural unit of polyester produced from one or more aromatic hydroxycarboxylic acids selected from phenyl-4-hydroxybenzoic acid. The above structural unit ()/[()+()] is 20~
100 mol%, preferably 70-100 mol%, and 20
If it is less than mol%, the effect of the present invention is small. Also, the above structural unit ()/[()+()+
()] is preferably 20 to 100 mol%. Of the aromatic polyester structural units used in the present invention, the structural unit () is essential, and the high intermolecular interaction of 4,4'-diphenyldicarboxylic acid, which is one of the components constituting the structural unit (), makes this It is considered that the purpose of the invention can be achieved. Further, the aromatic polyester used in the present invention can be produced according to the conventional polyester polycondensation method,
Although there are no particular limitations, representative manufacturing methods include, for example, the following methods (1) to (4). (1) Acylated products of aromatic dihydroxy compounds, acylated products of aromatic hydroxycarboxylic acids, and 4.
A method for producing from an aromatic dicarboxylic acid such as 4'-diphenyl dicarboxylic acid by deacetic acid polycondensation reaction. (2) A method for producing an aromatic dihydroxy compound from an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid such as 4,4'-diphenyldicarboxylic acid, and acetic anhydride by a deacetic acid polycondensation reaction. (3) A method for producing by dephenol polycondensation from an aromatic dihydroxy compound, a diphenyl ester of an aromatic dicarboxylic acid such as 4,4'-diphenyldicarboxylic acid, and a phenyl ester of an aromatic hydroxycarboxylic acid. (4) Aromatic hydroxycarboxylic acids and 4,4'-
A method in which an aromatic dicarboxylic acid such as diphenyl dicarboxylic acid is reacted with a desired amount of diphenyl carbonate to convert the carboxyl group into phenyl ester, and then an aromatic dihydroxy compound is added and a phenol-decondensation polycondensation reaction is performed. Acetic acid No. 1 is used as a catalyst for polycondensation reaction.
Metal compounds such as tin, tetrabutyl titanate, lead acetate, antimony trioxide, magnesium, sodium acetate, potassium acetate and trisodium phosphate are representative, and are particularly effective in dephenol polycondensation. The aromatic polyester that can be preferably used in the present invention forms an anisotropic melt phase, but under conditions of a shear rate of 1000 (1/sec) at a temperature 60°C higher than the temperature at which it starts to exhibit anisotropy (liquid crystal initiation temperature). Those having a measured melt viscosity of 10 to 15,000 poise can be preferably used. In addition, the aromatic polyester forming the anisotropic melt phase used in the present invention can be measured using a differential scanning calorimeter (DSC).
The heat of crystal fusion measured at a heating rate of 20℃/min is
It is necessary that it is 0.1 cal/g or less. If the heat of crystal fusion is greater than 0.1 cal/g, the adhesive strength between the layers of the composite injection molded article tends to decrease, which is not preferable because problems such as interlayer peeling occur. The composite injection molded article of the present invention is formed by a multilayer composite of one or more types of polymers, and the most preferred is a multilayer composite molded article in which the above-mentioned aromatic polyesters of the same type or different types are combined. In this case, the thickness of the layer is
It is 0.2 mm or more, preferably 0.8 mm or more. Furthermore, it is also possible to reduce anisotropy, which is a drawback of liquid crystal polymers, by forming a multilayer composite such that the flow directions of the injection molded products in each layer intersect with each other by 30° or more. By performing multilayer composite injection molding of these aromatic polyesters, for example, when performing multilayer sandwich molding, the elastic modulus of a single layer molded product can be made almost equal to the elastic modulus of a multilayer molded product. The thickness (t) of the molded product is almost equal to the modulus of elasticity at the thickness (nt) of the multilayer (n layer) molded product, which is a drawback of aromatic polyester that forms an anisotropic melt phase. It is possible to suppress a significant decrease in the elastic modulus when changing from the thickness (t) to the molded product thickness (nt). On the other hand, when a thermoplastic polymer other than an aromatic polyester capable of forming an anisotropic melt phase is used, examples of the thermoplastic polymer include polyethylene terephthalate, polybutylene terephthalate, amorphous polyarylate,
Polyester polycarbonate, polycarbonate, polysulfone, polyether sulfone, polyether ketone, polyether ether ketone,
Polyetherimide, polyphenylene sulfide, nylon 6, nylon 4,6, nylon 6,
6. Examples include polyethylene, polypropylene, polystyrene, ADS, etc., but many of the aromatic polyesters that form an anisotropic melt phase have linear expansion coefficients of 10 ^-6 cm/cm/°C or less in the flow direction, so these are By adding reinforcing agents and fillers such as glass fiber and carbon fiber to thermoplastic polymer, the coefficient of linear expansion is increased to 5x.
It is preferable to keep it below 10 ^-5 cm/cm/°C. By using these thermoplastic polymers in combination with aromatic polyesters capable of forming an anisotropic melt phase, it is also possible to obtain thick, high-modulus multilayer composite injection molded products. In order to carry out multilayer composite injection molding of one or more types of polymers in this way, an injection molding machine having two or more injection units is used, and a sandwich injection molding machine (for example, synthetic resin 17 , (5), 54 (' 71)), two-color injection molding machines (or multi-material injection molding machines), and mixed-color injection molding machines. Although these injection molding machines are well known, thermotropic polymers have never been molded with these machines, and by using these molding machines, the biggest drawback of thermotropic polymers is the molded product. It cannot be predicted from conventional knowledge that the decrease in elastic modulus when the thickness is large can be suppressed. By using these molding machines, multilayer composite injection molded products can be obtained. Note that at least one of the polymers of the present invention is an aromatic polyester that forms an anisotropic melt phase, and a reinforcing agent such as glass fiber, carbon fiber, asbestos, etc.
Additives such as fillers, nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents and flame retardants, as well as other thermoplastics, are added to impart desired properties to the molded article. be able to. The multilayer composite injection molded article of the present invention has an extremely high modulus of elasticity due to its structure and the characteristics of the aromatic polyester that forms an anisotropic melt phase. Examples will be described below. <Example> Example 1 324 parts by weight of p-acetoxybenzoic acid, 137 parts by weight of chlorohydroquinone diacetate, and 162 parts by weight of phenylhydroquinone diacetate were mixed with a stirring blade,
The mixture was charged into a reaction vessel equipped with a distillation tube and acetic acid depolymerization was performed. First, under a nitrogen gas atmosphere at 250 to 330℃ without stirring.
After reacting for 1.5 hours, stirring was started at 330°C, and the reaction was continued for an additional 1.25 hours. After that, the temperature was raised to 350℃, and the pressure inside the system was gradually reduced to 0.5mmHg.
When the reaction was continued for an additional 1.0 hour to complete polycondensation, almost the theoretical amount of acetic acid was distilled out, and a polymer having the following theoretical structural formula was obtained. In addition, we confirmed the optical anisotropy by placing this polyester on the sample stage of a polarizing microscope and increasing the temperature.
The temperature was 261°C, showing good optical anisotropy. The logarithmic viscosity of this polyester (pentafluorophenol solution 0.1 g/dl, 60°C) is 3.68, and at 320°C
The melt viscosity at a shear rate of 1000 (1/s) is
It was 2000 poise. The thermal properties of this polymer were measured using a PerkinElmer DSC-type at a heating rate of 20°C/min, but no melting point was detected. This polymer was molded under the following conditions to obtain a three-layer composite injection molded product having a thickness of 8 mm. Using a Sumitomo-Nestal two-color injection molding machine manufactured by Sumitomo Heavy Industries, Ltd., which has a maximum mold clamping force of ²⁵ tons, a maximum injection amount of 20.4 cc, and a maximum injection pressure of 1900 Kgf/cm2, the above aromatic polyester is molded at a cylinder temperature of 290 to 310. After injection molding inner layer 1 of 3 x 8 x 70 mm at a nozzle temperature of 320°C, the mold was inverted and both sides of the inner layer were coated with the same polymer.
Sandwich molding with outer layer 2 of 2.5 x 8 x 60 mm,
A composite injection molded product consisting of three layers and having a cross section as shown in FIG. 1 and having a thickness of 8 mm was obtained. In order to measure the elastic modulus of the outer layer and inner layer of this molded product, the three-layer molded product was cut into three layers and the bending elastic modulus of each sample was measured using Tensilon UTM-4 model manufactured by Toyo Baldwin Co., Ltd. Distance between spans 40
mm, and the strain rate was 1 mm/min. As a result, as shown in Table 1, the flexural modulus of the outer layer was 17.9GPa, and the flexural modulus of the inner layer was 17.9GPa.
It was 20.8GPa. On the other hand, only the inner layer (thickness 3mm)
The flexural modulus of the molded product injection molded is 21.2GPa, and the flexural modulus of the outer layer and inner layer samples obtained by cutting these shows that even though the skin layer is cut, only the inner layer is molded. It was found that the flexural modulus of elasticity was almost the same as that of the sample obtained by On the other hand, instead of a composite molded product consisting of three layers, a single-layer molded product of 8 x 8 x 60 mm was injection molded, and three layers of the single-layer molded product were added to the thickness corresponding to the outer layer (2.5 mm thickness) and inner layer (3 mm thickness). When the flexural modulus was measured by cutting, it was found that the elastic modulus of the outer layer was 11.5 GPa, the inner layer was 10.7 GPa, and the elastic modulus decreased more than that of the three-layer composite molded product of the present invention. Furthermore, the obtained three-layer composite injection molded product was divided into two equal parts in the length direction, and the shear adhesive strength between the layers was measured using Tensilon UTM-1 manufactured by Toyo Baldwin Co., Ltd. using the method shown in Figure 2. 11.6Kg/cm ²
It had high adhesive strength.

[Table] Example 2 360 parts by weight of p-acetoxybenzoic acid, 129 parts by weight of hydroquinone diacetate, 167 parts by weight of t-butylhydroquinone diacetate, and 4,
323 parts by weight of 4′-diphenyldicarboxylic acid was added to the stirrer using a stirring blade.
After charging into a reaction vessel equipped with a distillation tube and reacting at 250 to 330°C in a nitrogen gas atmosphere for 1.5 hours without stirring,
Stirring was started at 330°C and the reaction was continued for an additional 1.5 hours.
After that, the temperature was raised stepwise to 350℃ and 360℃, and the pressure inside the system was gradually reduced to 0.5mmHg.
When the reaction was carried out for 1.25 hours to complete polycondensation, almost the theoretical amount of acetic acid was distilled out, and a polymer having the following theoretical structural formula was obtained. In addition, we confirmed the optical anisotropy by placing this polyester on the sample stage of a polarizing microscope and increasing the temperature.
It showed good optical anisotropy at 260°C. The logarithmic viscosity of this polyester was 3.25 as a result of measurement under the same conditions as in Example 1, and the shear rate was 1000 at 320°C.
The melt viscosity at (1/sec) was 5800 poise.
Also, as in Example 1, DSC was performed at a heating rate of 20°C/min.
When the melting point and heat of crystal fusion were measured using a method, the melting point was 294°C, and the heat of crystal fusion was 0.08 cal/g. This polymer was molded using the same molding machine as in Example 1,
A three-layer composite injection molded product was molded at a cylinder temperature of 290 to 330°C and a nozzle temperature of 330°C, and the flexural modulus of the inner layer and outer layer was measured in the same manner as in Example 1. The results are shown in Table 2.

[Table] Furthermore, when the shear adhesive strength between the layers of this three-layer composite injection molded product was measured in the same manner as in Example 1, it was found to have an adhesive strength of 3.3 Kg/cm ² . Comparative Example 1 343 parts by weight of methylhydroquinone diacetate,
327 parts by weight of 4,4'-diphenyldicarboxylic acid and 1,2-bis(phenoxy)ethane-4,4'-
45 parts by weight of dicarboxylic acid was charged into a reaction vessel equipped with a stirring blade and a distillation tube, and heated at 250 to 330°C under a nitrogen gas atmosphere.
After reacting for 1.5 hours without stirring, stirring was started at 330°C, and the reaction was continued for an additional 1.5 hours. After that, the temperature was raised stepwise to 350℃ and 370℃, the pressure inside the system was gradually reduced, and the reaction was further carried out for 1.0 hours at 0.5mmHg to complete the polycondensation, and almost the theoretical amount of acetic acid was distilled out. A polymer having the structural formula was obtained. We also confirmed the optical anisotropy by placing this polyester on the sample stage of a polarizing microscope and increasing the temperature.
It showed optical anisotropy at 295℃. The logarithmic viscosity of this polyester was measured under the same conditions as Example 1.
3.10, and the shear rate at 355℃ is 1000 (1/
The melt viscosity in seconds) was 6100 poise. Also,
The melting point and heat of crystal fusion were measured by DSC at a heating rate of 20°C/min as in Example 1.
The temperature was 341°C, and the heat of crystal fusion was 0.33 cal/g. This polymer was molded using the same injection molding machine as in Example 1, with a cylinder temperature of 330 to 360°C and a nozzle temperature of 370°C.
Although a three-layer composite injection molded product was molded at ℃, there was no adhesion between the layers at all, and peeling between the layers occurred as soon as the molded product was ejected from the mold. Comparative Example 2 A polymer having the following theoretical structural formula was polymerized. This polyester was placed on the sample stage of a polarizing microscope and heated to 251℃ to confirm the optical anisotropy.
It showed good optical anisotropy. The logarithmic viscosity of this polyester was measured under the same conditions as Reference Example 1.
5.38, and the shear rate at 310℃ is 1000 (1/
The melt viscosity in seconds) was 1250 poise. This polymer was heated at a heating rate of 20 using DSC as in Reference Example 1.
Measured at °C/min Melting point: 275 °C, heat of crystal fusion
It was 0.35 cal/g. This polymer was molded using the same injection molding machine as in Example 1, with a cylinder temperature of 260 to 300°C and a nozzle temperature of 300°C.
Although a three-layer composite injection molded product was molded at ℃, there was no adhesive force between the layers at all, and peeling between the layers occurred as soon as the molded product was ejected from the mold. <Effects of the Present Invention> It was found that the multilayer composite injection molded product of the present invention has good adhesion between layers, and the decrease in elastic modulus is small even when the molded product is thick.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a multilayer composite molded product, and FIG. 2 is a schematic diagram of an apparatus for measuring interlayer adhesive strength of a multilayer composite molded product. 1...Inner layer, 2...Outer layer, 3...Crosshead, 4...Sample, 5...Aluminum plate, 6...Load cell.

Claims (1)

[Scope of Claims] 1 At least one has the following structural formulas () to ()
from one or more aromatic polyesters capable of forming an anisotropic melt phase having a heat of crystal fusion of 0.1 cal/g or less as measured by differential scanning calorimetry (DSC) A multilayer composite injection molded product. (However, X in the formula represents one or more groups selected from [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] ] [Formula] [Formula] [Formula] [Formula] Indicates one or more groups selected from [Formula] and [Formula]. Also, Z is selected from [Formula] [Formula] [Formula] [Formula] (Indicates one or more groups.)