JPH0453901B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a polycarbonate resin composition with improved moldability and solvent cracking resistance. [Prior Art] Bisphenol-based aromatic polycarbonate (hereinafter sometimes simply referred to as polycarbonate) has been known as a molding resin with excellent physical and thermal properties. However, the polycarbonate has a high melt viscosity, and therefore the molding temperature and molding pressure are high compared to other resins, which has been considered to be a difficult point in molding. Furthermore, polycarbonate molded articles not only have poor hardness, but also have the disadvantage of being susceptible to cracking when subjected to concentrated stress in the presence of certain solvents. The high impact resistance inherent in polycarbonate,
It has been proposed to blend various polyesters into polycarbonate in order to improve the disadvantages of polycarbonate, such as low moldability and low solvent cracking resistance, without significantly impairing transparency and heat resistance. For example, Japanese Patent Publication No. 54-37633 describes an example in which a polyalkylene terephthalate copolymerized with an ethylene oxide adduct of bisphenol A as one of the diol components is blended with polycarbonate. An example of blending them into polycarbonate is disclosed in JP-A No. 53-94538. Furthermore, it is known that transparency can be improved by blending polyester polycarbonate into a composition of polycarbonate and polyalkylene terephthalate (Japanese Patent Application Laid-Open No.
55-145751). (Problems to be Solved by the Invention) However, the method described in Japanese Patent Publication No. 54-37633 uses an expensive diol such as an ethylene oxide adduct of bisphenol A, which is industrially disadvantageous. Furthermore, since the polyalkylene terephthalate blended in the method described in JP-A-53-94538 is an amorphous polyester, the effect of improving the solvent cracking resistance of polycarbonate cannot be said to be sufficient. Furthermore, in the method described in JP-A-55-145751, although the transparency of the composition of polycarbonate and polyalkylene terephthalate is improved by adding the polyester carbonate copolymer, the polyester disclosed in the invention When carbonate is added to a polycarbonate system alone, it is not only difficult to maintain the transparency of the polycarbonate itself, but also the effect of improving solvent cracking resistance cannot be sufficiently obtained. Therefore, the purpose of the present invention is to improve the moldability and solvent cracking resistance, which are the disadvantages of polycarbonate, without significantly impairing the good properties inherent to polycarbonate (high impact resistance, heat resistance, transparency). An object of the present invention is to provide an inexpensive polycarbonate composition that can improve the properties of polycarbonate. [Means for Solving the Problems] As a result of various studies to achieve the above object, the present inventors have found that a polyester copolymer obtained by a specific polymerization method can be used as a modifier for polycarbonate. Recognizing its superiority, the present invention was developed. That is, the present invention provides (a) bisphenol aromatic polycarbonate
100 parts by weight and (b) (a) a difunctional carboxylic acid mainly consisting of terephthalic acid or its ester-forming derivative, and a diol component having a number average degree of polymerization of 1 to 1;
(b) A polyester copolymer obtained by polycondensing 5 to 100 parts by weight of a bisphenol aromatic polycarbonate having a viscosity average molecular weight of 5000 or more to 100 parts by weight of a polyester precursor having a viscosity average molecular weight of 5,000 or more. This is a polycarbonate resin composition prepared by mixing 5 to 200 parts by weight. Here, the viscosity average molecular weight M is determined by the following intrinsic viscosity [η] measured in dichloromethane at 20°C.
This is a value determined by Schnell's formula. [η] = 1.23×10 ^-5 M ⁰ . ⁸³ The bisphenol aromatic polycarbonate used as one component of the composition or one component of the copolymer in the present invention is represented by the following general formula (). It is a polymer having a structural unit of (In the formula, Z ² is a bond or alkylene having 1 to 8 carbon atoms, alkylidene having 2 to 8 carbon atoms, cycloalkylene having 5 to 15 carbon atoms, cycloalkylidene having 5 to 15 carbon atoms, SO ₂ , SO, O, CO or R ₁ and R ₂ each represent a hydrogen, chlorine or bromine atom or a saturated alkyl group having 1 to 8 carbon atoms. Further, p and q each represent an integer from 0 to 4. ) The following can be mentioned as suitable examples of the structural unit of formula (). These bisphenol-based aromatic polycarbonates are conventionally known and can be easily produced by the known phosgene method or transesterification method using an aromatic dihydroxy compound or a derivative thereof as a main raw material. The polyester precursor used in the present invention is composed of a difunctional carboxylic acid, mainly terephthalic acid, or its ester-forming derivative (hereinafter, these may be collectively referred to as the dicarboxylic acid component) and a diol component. Terephthalic acid type (poly) having the structural unit of the following general formula ()
It is ester. (Here, Z ¹ in the formula is a divalent residue obtained by removing the hydroxyl group from a diol, and n is a number from 1 to 30.) A polyester in which the dicarboxylic acid component is other than terephthalic acid, for example, the main component is an aliphatic dicarboxylic acid. When a precursor is used, the resulting copolymer does not have the property of sufficiently improving the solvent cracking resistance of polycarbonate. As the dicarboxylic acid component, other dicarboxylic acid components other than the terephthalic acid component can be used in combination within a range that does not impair the effects of the present invention. They include, for example, aliphatic dicarboxylic acids such as oxalic acid, malonic acid, adivic acid, suberic acid, azelaic acid, sebacic acid or decanedicarboxylic acid, and aromatic dicarboxylic acids such as isophthalic acid or naphthalenedicarboxylic acid and their ester-forming properties. It is a derivative. The content of these other dicarboxylic acid components is generally 20 mol% of the total dicarboxylic acids.
within Although there are no particular limitations on the diol component, the following are exemplified. They are ethylene glycol,
1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, 1,8
- aliphatic diols having from 2 to 15 carbon atoms, such as octanediol, neopentyl glycol or 1,10-decanediol, diethylene glycol, triethylene glycol, polyethylene glycol or poly(tetramethylene oxide)-α,ω-diol; and random or block copolymers of ethylene oxide and 1,2-propylene oxide. Especially 1,
It is preferable to use 4-butanediol or ethylene glycol in an amount of 80 mol % or more based on the total glycol components, since the solvent crack resistance of the polycarbonate can be dramatically increased. The above diol component and dicarboxylic acid component are induced into a polyester precursor by a conventional polycondensation method. Generally, it is obtained by heating both in the presence or absence of a polycondensation catalyst and distilling by-product water, lower alcohol, etc. out of the system. In the present invention, it is essentially important that the number average degree of polymerization of the polyester precursor is in the range of 1 to 30. When the number average degree of polymerization of the polyester precursor is within this range, the resulting copolymer has high blocking properties. When the highly blocking copolymer is mixed with polycarbonate, the drawbacks of polycarbonate can be improved without impairing its original physical properties. When the number average degree of polymerization of the polyester precursor is less than 1, that is, when the dicarboxylic acid component and the diol component have not substantially reacted, adding polycarbonate to the system for copolymerization will result in The blocking properties of the polymer are reduced. The object of the present invention is to improve the solvent cracking resistance without impairing the good properties originally possessed by polycarbonate even when the copolymer with low blocking properties (high randomness) is blended into polycarbonate. is not achieved. On the other hand, if the number average degree of polymerization of the polyester precursor exceeds 30, it becomes difficult to uniformly disperse the polyester precursor and polycarbonate, making it difficult to obtain a copolymer with high blocking properties. In the present invention, the average degree of polymerization of the polyester precursor is 1
〜20. The viscosity average molecular weight (hereinafter simply referred to as molecular weight) of the polycarbonate subjected to copolymerization in the present invention is 5000 or more, more preferably 8000 to 8000.
In the range of 100000. When the molecular weight is within the above range, a copolymer with high blocking properties is easily obtained. A method of obtaining a copolymer by directly adding phosgene and a bisphenol compound to polyester or its precursor, or a method of obtaining a copolymer by copolymerizing oligocarbonate with a molecular weight of less than 5000 with polyester or its precursor, The blocking properties of polycarbonate units are low. Even if the copolymer with low blocking properties is blended into polycarbonate, the object of the present invention, which is to improve the solvent cracking resistance without impairing the good properties originally possessed by polycarbonate, cannot be achieved. In the present invention, the measure of blockiness can be expressed by the melting point depression of the obtained copolymer.
For example, when the ester component constituting the copolymer is crystalline, the melting point based on the polyester units in the copolymer preferably satisfies the following formula. Do not copolymerize polycarbonate Melting point of polyester without copolymerizing polycarbonate (°C) − Melting point based on polyester units in copolymer (°C) ≦0.015×(Number of moles of polycarbonate units in copolymer/in copolymer The copolymerization ratio of the polyester precursor and polycarbonate in the present invention is
The amount of polycarbonate is 5 to 100 parts by weight per 100 parts by weight. If the copolymerization ratio of polycarbonate is too low, it will be difficult to maintain the excellent physical properties of polycarbonate. On the other hand, if the copolymerization ratio of polycarbonate is too high, the effect of improving the defects of polycarbonate will not be sufficient.
The most preferable copolymerization ratio is polyester precursor
The amount of polycarbonate is 5 to 30 parts by weight per 100 parts by weight. The copolymerization method employed in the present invention is achieved by mixing a predetermined amount of the specific polyester precursor and polycarbonate and subjecting the mixture to normal polyester polymerization conditions. Most simply, after producing the polyester precursor, the desired copolymer can be obtained by adding polycarbonate to the system and continuing polymerization. The polyester copolymer obtained by the above method is mixed in an amount of 5 to 200 parts by weight per 100 parts by weight of the bisphenol aromatic polycarbonate.
If the amount is less than 5 parts by weight, the effect of improving the physical properties of polycarbonate, which is the object of the present invention, will not be sufficient. On the other hand, if the mixing amount exceeds 200 parts by weight, the resulting composition will no longer exhibit the properties inherent to polycarbonate resin (eg, high impact strength). A preferred mixing ratio is 10 to 50 parts by weight of the polyester copolymer per 100 parts by weight of the polycarbonate. Note that the effects of the present invention (particularly transparency) become remarkable by mixing the copolymer with a bisphenol-based aromatic polycarbonate having the same structure as that subjected to copolymerization. The preferred molecular weight of this bisphenol aromatic polycarbonate is 5,000 to 100,000. In order to obtain the polycarbonate resin composition of the present invention, various methods commonly used for adding plasticizers or fillers to thermoplastic resins may be used to mix the polycarbonate and polyester copolymer. I can do it. For example, an extruder, a Banbury mixer, a kneading roll, etc. can be used. Various fillers can be mixed into the resin composition of the present invention, if necessary. These fillers include carbon black, titanium oxide, alumina, silica, talc, glass fiber, asbestos,
Other pigments and dyes etc. For molding, conventional thermoplastic resin molding methods, such as extrusion molding, injection molding, compression molding, and calender molding, can be used as is. [Example] Next, the present invention will be specifically explained with reference to Examples. In addition, η _SP in the examples is 0.5 in a phenol/tetrachloroethane mixed solvent (1:1 weight ratio).
g/dl, a value measured at 30°C. Synthesis Examples 1, 2, 11, 18, and 19 2.5 kg of dimethyl terephthalate, 1.8 kg of ethylene glycol, and 1 g of zinc acetate dihydrate were heated and stirred at 190°C to perform transesterification. After almost a predetermined amount of methanol has been distilled off, triphenyl phosphate
1.2 g and 1.1 g of antimony oxide were added. 240℃
When the temperature was raised to , the pressure was reduced using an aspirator, and stirring was continued for 15 minutes, a polyethylene terephthalate oligomer (polyester precursor) with a number average degree of polymerization of 10 was obtained. The degree of polymerization was measured by the terminal group assay method. After returning the system to normal pressure, bisphenol A polycarbonate (manufactured by Idemitsu Petrochemical Co., Ltd., Idemitsu Polycarbonate A-3000, viscosity average molecular weight 29000)
(Synthesis Example 1, 380g; Synthesis Example 2,
620g; Synthesis example 11, not added; Synthesis example 18, 80g;
Synthesis Example 19, 3000 g) While kneading, the pressure was again reduced using an aspirator. After reaching 50 torr, the temperature of the system was increased to 280°C over 10 minutes. After 15 minutes, the degree of reduced pressure was increased to 0.2 torr using a vacuum pump, and heating and stirring were continued. After 2 hours, the reaction was stopped, and the reactant was taken out and rapidly cooled. Synthesis examples 1, 2, 18 and 19
The product obtained is transparent and contains methylene chloride, which is a good solvent for polycarbonate but a non-solvent for polyethylene terephthalate, and phenol/tetrahydrofuran (1:1 by weight, which is a good solvent for polyethylene terephthalate but a non-solvent for polycarbonate). ratio) Even when dissolved in a mixed solvent, it was not separated. This confirmed that the products obtained in Synthesis Examples 1, 2, 18, and 19 were copolymers in which a polyester component and a polycarbonate component were chemically bonded. Analysis results of the copolymers by DSC (differential scanning calorimetry) showed that all copolymers had melting points between 252 and 256°C, indicating that the copolymers had blocked polyethylene terephthalate segments. It was confirmed that it was a copolymer. Note that the melting point of the polyethylene terephthalate homoprimer obtained in Synthesis Example 11 was 260°C. Synthesis Example 3 Instead of using 1.8Kg of ethylene glycol in Synthesis Example 1, 1.26Kg of ethylene glycol and 1,4
-Cyclohexane dimethanol Polycondensation was carried out in exactly the same manner except that 1.25 kg of mixed diols (molar ratio 0.7/0.3) were used. As a result of the same solvent test as in Synthesis Example 1, the obtained product was not separated by the solvent, so it was confirmed that the product was copolymerized. Synthesis Example 12 In Synthesis Example 1, dimethyl terephthalate and ethylene glycol were charged and at the same time polycarbonate was blended, and the reaction proceeded in accordance with Synthesis Example 1 to obtain a product. It was confirmed that the obtained product was copolymerized by the same solvent test as in Synthesis Example 1, but the melting point of the polyethylene terephthalate component was not clearly recognized in the DSC analysis results. Synthesis Example 13 After obtaining a polyester having a number average degree of polymerization of 100 according to Synthesis Example 1, polycarbonate was added and a polymerization reaction was carried out in the same manner as in Synthesis Example 1. The obtained product was opaque when melted, and as a result of a solvent test, it was confirmed that most of the product was separable and was not chemically copolymerized. In addition, the product had an insoluble portion in the viscosity measurement solvent, making it impossible to measure the viscosity. Synthesis Examples 14, 15 and 16 Polymers were obtained in the same manner as in Synthesis Example 1, except that a predetermined amount of polycarbonate having a viscosity average molecular weight of 2600 was used as the polycarbonate added in Synthesis Example 1. The melting point corresponding to the polyethylene terephthalate segment of the obtained polymer is 250°C when the amount of polycarbonate added is 5 parts by weight (Synthesis Example 14) relative to 100 parts by weight of the polyester precursor, and 10 parts by weight (Synthesis Example 15). and 15 parts by weight (Synthesis Example 16), a clear melting point was no longer observed. Synthesis Example 17 A polyester copolymer was obtained in exactly the same manner as in Synthesis Example 3 except that the bisphenol polycarbonate was not added. Synthesis example 4 2.5Kg of dimethyl terephthalate, 2.6Kg of 1,4-butanediol, 1g of tetrabutyl titanate
The mixture was stirred and heated to 190°C to carry out transesterification.
After approximately the predetermined amount of methanol had distilled out, the temperature was raised to 240°C, the pressure was reduced using an aspirator, and stirring was continued for 15 minutes. A polybutylene terephthalate oligomer (polyester precursor) with a number average degree of polymerization of 10 was obtained. Ta. Thereafter, a predetermined amount of polycarbonate was added in the same manner as in Synthesis Example 1 to perform polycondensation. As a result of the same solvent test as in Synthesis Example 1, it was confirmed that the obtained product was copolymerized because the product could not be separated by the solvent. Example 100 parts by weight of bisphenol A polycarbonate (manufactured by Idemitsu Petrochemical Co., Ltd., Idemitsu Polycarbonate A-3000, viscosity average molecular weight 29000) and a predetermined amount of the product obtained in the above synthesis example were each added to 120 parts by weight.
After drying for 12 hours at
-40-28 model) and kneaded and pelletized under the following conditions. Cylinder temperature: 270−275− from the hopper side
275-280℃ Adapter temperature: 270℃ Die temperature: 270℃ After drying the obtained pellets at 120℃ for 12 hours,
A test piece was obtained by injection molding using a Nippon Steel Ankelberg model V-15-75 injection molding machine (mold temperature: 120°C). Melt index of pellets (280°C, g/10 minutes) as a guide for moldability and fluidity of the composition
The tensile impact strength (ASTMD-1822 standard) was measured as a measure of impact resistance, and the haze value (haze) of a 3 mm thick molded piece was measured as a measure of transparency. As a guideline for solvent cracking resistance, toluene/isooctane (40/60 volume ratio) was used as the solvent, and the critical strain was measured by the 1/4 ellipse method (Reference: Nakatsuji, Shikizai, 39 455 (1966)). . The results are shown in Table 1.

【table】

[Table] As can be seen from Table 1, the polycarbonate composition mixed with the copolymer produced by the production method of the present invention has improved fluidity and solvent cracking resistance without significantly reducing the original impact resistance and transparency of polycarbonate. Improvements were approved. On the other hand, in Composition No. 6 and Composition No. 14, in which polyester that is not copolymerized with polycarbonate was used as a modifier for polycarbonate, although the fluidity and solvent cracking resistance of the polycarbonate were improved, it was observed that the transparency was significantly reduced. It was done. Composition No. 7, which used a copolymer in which polycarbonate was added during polycondensation of dimethyl terephthalate and ethylene glycol, maintained transparency, but the effect of improving solvent cracking resistance was poor. On the other hand, the number average degree of polymerization
Composition No. 8, which uses a product obtained by adding polycarbonate to polyethylene terephthalate (100) and performing a reaction, had a haze of more than 10 and the original transparency of the polycarbonate was significantly reduced. Furthermore, the molecular weight of the added polycarbonate is
Composition No. 9 using a copolymer with a molecular weight lower than 5000 had transparency similar to Composition No. 7, but no improvement in solvent cracking resistance was observed. (Effects of the Invention) According to the present invention, a composition is provided that has improved fluidity and solvent cracking resistance, which are disadvantages of polycarbonate, without significantly reducing the original impact resistance and transparency of polycarbonate.

Claims (1)

[Scope of Claims] 1. (a) 100 parts by weight of a bisphenol-based aromatic polycarbonate, and (b) (a) synthesized from a difunctional carboxylic acid mainly consisting of terephthalic acid or its ester-forming derivative and a diol. (b) 5 to 100 parts by weight of a bisphenol aromatic polycarbonate having a viscosity average molecular weight of 5000 or more is added to 100 parts by weight of a polyester precursor having a number average degree of polymerization of 1 to 30, and polycondensation is performed. A polycarbonate resin composition prepared by mixing 5 to 200 parts by weight of a polyester copolymer. 2. The composition according to claim 1, which uses a polyester copolymer whose melting point based on polyester units satisfies the following formula. Melting point of polyester without copolymerizing polycarbonate (°C) - Melting point based on polyester units in the copolymer (°C) ≦0.015×(Number of moles of polycarbonate units in the copolymer/Number of moles of polycarbonate units in the copolymer 3. The resin composition according to claim 1, which uses a polyester precursor having a structural unit represented by the following general formula (). (In the formula, Z ¹ is an ethylene group or a tetramethylene group, and n is a number from 1 to 30.)