JPH06145319A - Copolyester and its production - Google Patents

Abstract

PURPOSE:To obtain a copolyester which can give an optical material having good transparency and excellent moldability, heat resistance, dimensional stability and chemical resistance and being economically profitable. CONSTITUTION:A substantially linear copolyester is produced from a mixture comprising 2,6-naphthalenedicarboxylic acid or its esterifiable derivative and terephthalic acid or its esterifiable derivative, a dihydroxy compound having aromatic rings in the main chain and side chains and represented by the formula wherein R1 is 2-4C alkylene; R2 is hydrogen, 1-7C alkyl, allyl or aralkyl; R3, R4 and R5 may be the same or different from each other and are each hydrogen or 1-4C alkyl; and l, m and n are each an integer of 1 or 2, and a 2-4C aliphatic glycol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester copolymer and a method for producing the same, more specifically, it has excellent transparency, heat resistance, chemical resistance, small birefringence, and excellent dimensional stability. The present invention relates to a polyester copolymer particularly suitable as a substrate and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, glass has been most frequently used as an optical material, but glass is excellent in transparency.
Although it has the advantage of small optical anisotropy, it has the drawbacks of poor moldability, heavy weight, and uneconomical. Therefore, in recent years, researches on plastic optical materials such as polycarbonate (PC) and polymethylmethacrylate (PMMA), which replace glass, have been actively conducted. Actually, PC or P
Many MMA lenses are commercially available, and PCs are often used for transparent parts of automobiles in order to reduce their weight. However, PC has poor fluidity and poor chemical resistance. PMMA has a high water absorption rate and poor dimensional stability.
In addition, the use of optical discs for recording and reproducing information such as voices, images and characters using laser light has been rapidly expanding in recent years. The material for the substrate is required to have physical properties such as low birefringence, excellent transparency, and heat resistance, so that these products are currently quite expensive. Conventionally,
Such optical disc substrates include PC, PMMA,
Transparent plastic materials such as amorphous polyolefin (APO) have been used. Further, a special aromatic polyester copolymer resin (JP-A-57-20864, JP-A-2-98845, JP-A-2-38428) has been proposed.

However, although PC has high heat resistance and excellent transparency, it has the drawbacks of poor moldability and large birefringence. In addition, since it has poor chemical resistance, it cannot be said to be perfect as a glass substitute material. Further, PMMA has excellent moldability and small birefringence, but has a drawback that it has high hygroscopicity and is liable to undergo deformation such as warpage when formed into a molded product. APO has small birefringence and is excellent in heat resistance and dimensional stability.
It is extremely expensive. On the other hand, all of the reported special aromatic polyester resins are not always satisfactory because they have insufficient optical properties, insufficient heat resistance, or use expensive raw materials. That is,
It is desired to develop an optical material having excellent transparency, heat resistance, moldability, dimensional stability, and chemical resistance, and further to develop an optical disk substrate having a small birefringence made of such a material.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies in view of the above problems, and as a result, a polyester polymer having a specific composition has excellent optical properties. It has been found that an excellent optical disk substrate can be obtained, and the present invention has been completed. The purpose is to have a small optical anisotropy, transparency, heat resistance,
An object of the present invention is to provide an optical material having excellent moldability and dimensional stability and good chemical resistance, and a method for producing an optical disk substrate having a small birefringence made of the optical material. Other objects and effects of the present invention will be apparent from the following description.

[0005]

That is, the present invention is 2,6-
A mixed composition of naphthalenedicarboxylic acid or an ester-forming derivative thereof and terephthalic acid or an ester-forming derivative thereof; and a general formula (1)

[Chemical 3] (Wherein R ₁ is an alkylene group having 2 to 4 carbon atoms, R ₂ is hydrogen or an alkyl group having 1 to 7 carbon atoms, an allyl group, an aralkyl group, R ₃ , R ₄ and R ₅ are hydrogen. Or an alkyl group having 1 to 4 carbon atoms, which may be the same or different, and l, m, and n each represent an integer of 1 or 2). This is achieved by a substantially linear aromatic polyester copolymer comprising a ring-containing dihydroxy compound and an aliphatic glycol, and a method for producing the same.

The above polyester copolymer is 2,6
-A mixed composition of naphthalenedicarboxylic acid or an ester-forming derivative thereof and terephthalic acid or an ester-forming derivative thereof, a dihydroxy compound having an aromatic ring in the main chain and side chains represented by the general formula (1), and a fat Aromatic polyester copolymers obtained by polycondensation by heating and stirring group glycols in the presence of a catalyst to carry out an esterification reaction or transesterification reaction, and then raising the temperature further and under high vacuum and heating conditions. This is used for molding to obtain a polyester copolymer molded product. As the component of the dicarboxylic acid used for the aromatic polyester copolymer of the present invention, 2,6-naphthalenedicarboxylic acid or its ester-forming derivative and terephthalic acid or its ester-forming derivative are used.
The composition ratio of the 2,6-naphthalenedicarboxylic acid component is 60 mol% or more and 90 mol%, and the terephthalic acid component is 10 to 10.
It is 40 mol%. When the composition ratio of 2,6-naphthalenedicarboxylic acid is 60% or less, the heat resistance decreases. or,
If it is 90% or more, the moldability of the molded product deteriorates.

In the present invention, examples of the dihydroxy compound having a benzene ring in the main chain and side chain represented by the general formula (1) include 1,1-bis (4-hydroxyethoxyphenyl) 1-phenylmethane, 1,1-bis (4
-Hydroxyethoxyphenyl) 1-phenylethane,
1,1-bis (4-hydroxyethoxyphenyl) 1-
Phenyl-n-propane, 1,1-bis (4-hydroxyethoxyphenyl) 1-phenyl-2 methylpropane, 1,1-bis (4-hydroxyethoxyphenyl)
1-phenyl-n-butane, 1,1-bis (4-hydroxyethoxyphenyl) 1-phenyl-n-pentane,
1,1-bis (4-hydroxyethoxyphenyl) 1-
Phenyl-n-hexane, 1,1-bis (4-hydroxyethoxyphenyl) 1-phenyl-n-heptane,
1,1-bis (4-hydroxyethoxy-3-methylphenyl) 1-phenylethane, 1,1-bis (4-hydroxyethoxy-3-tert-butylphenyl) 1-
Phenylethane, 1,1-bis (4-hydroxyethoxy-3,5-dimethylphenyl) 1-phenylethane,
1,1-bis (4-hydroxyethoxy-3,5-di (tert-butylphenyl)) 1-phenylethane,
1,1-bis (4-hydroxyethoxyphenyl) 1-
(4-Methylphenyl) ethane, 1,1-bis (4-hydroxyethoxyphenyl) 1- (3-thymerphenyl) ethane, 1,1-bis (4-hydroxyethoxy-)
3-methylphenyl) -1- (3-methylphenyl) ethane, 1,1-bis (4-hydroxyethoxy-3-t)
ert-butylphenyl) -1- (3-methylphenyl) ethane, 1,1-bis (4-hydroxyethoxyphenyl) -1- (2,3-dimethylphenyl) ethane,
1,1-bis (4-hydroxyethoxyphenyl) -1
-(2,4-Dimethylphenyl) ethane, 1,1-bis (4-hydroxyethoxyphenyl) -1- (3,5-
Dimethylphenyl) ethane (3-methylphenyl) ethane, 1,1-bis (4-hydroxyethoxy-3-methyl-6-tert-butylphenyl) -1- (3,5-
Dimethylphenyl) ethane, 1,1-bis (4-hydroxypropoxyphenyl) -1-phenylethane, 1,
1,1-bis (4-hydroxyalkoxyphenyl) -1-monophenylalkanes such as 1-bis (4-hydroxyethoxyphenyl) -1-phenyl-propane,

1,1-bis (4-hydroxyethoxyphenyl) -1,1-diphenylmethane, 1,1-bis (4-hydroxyethoxy-3-methylphenyl)-
1,1-diphenylmethane, 1,1-bis (4-hydroxyethoxy-2-methylphenyl) -1,1-diphenylmethane, 1,1-bis (4-hydroxyethoxy-
2,6-Dimethylphenyl) -1,1-diphenylmethane, 1,1-bis (4-hydroxyethoxy-3-te)
rt-butylphenyl) -1,1-diphenylmethane,
1,1-bis (4-hydroxyethoxy-2,6-di-
tert-butylphenyl) -1,1-di (3-methylphenyl) methane, 1,1-bis (4-hydroxyethoxyphenyl) -1,1-di (4-tert-butylphenyl) methane, 1,1 -Bis (4-hydroxybutoxyphenyl) -1,1-diphenylmethane, 1,1-bis (4-hydroxypropoxy-3-methylphenyl)
Examples thereof include 1,1-bis (4-hydroxyalkoxyphenyl) -1,1-diphenylmethanes such as -1,1-diphenylmethane, which may be used alone or in combination of two or more kinds.

Of these, 1,1-bis (4-hydroxyethoxyphenyl) -1-phenylalkanes, 1,
1-bis (4-hydroxyethoxyphenyl) -1,1
1,2-bis (4-hydroxyethoxyphenyl) -1-phenylethane, 1,1-bis (4), which is good in diphenylalkanes, has a remarkable effect of reducing birefringence, and improves the glass transition temperature. -Hydroxyethoxyphenyl) -1,1-diphenyl-methane and its derivatives are preferred.

The polyester of the present invention contains at least one dihydroxy compound having an aromatic ring in the main chain and side chain represented by the general formula (1) in a proportion of 5 to 95 mol% with respect to the total dicarboxylic acid component. Preferably 10
It is composed of 80 mol%. When the composition of the dihydroxy compound represented by the general formula (1) having an aromatic ring in the main chain and side chains is less than 5 mol%, the optical anisotropy becomes large. Also,
When it is 95 mol% or more, the polymerization reaction does not easily proceed during the production of the polymer, and it is difficult to reach a sufficient degree of polymerization.

In the present invention, as the aliphatic glycol, ethylene glycol, 1,3 propanediol,
1,2-propanediol, 1,4-butanediol,
1,3-butanediol, 1,2-butanediol,
Examples include diols such as 1,5-pentanediol, 1,4-pentanediol, 1,3-pentanediol, and 1,2-pentanediol, and alicyclic dimethanols such as cyclohexanedimethanol and cyclopentanedimethanol. Among them, ethylene glycol and 1,4-butanediol are preferred, and ethylene glycol is most preferred. These may be used alone or in combination of two or more.

A mixed composition of 2,6-naphthalenedicarboxylic acid of the present invention or an ester-forming derivative thereof and terephthalic acid or an ester-forming derivative thereof, and a main chain and a side chain represented by the general formula (1) Polyester copolymers composed of a dihydroxy compound having an aromatic ring and an aliphatic glycol can be prepared by, for example, transesterification method, direct polymerization method,
It can be produced by selecting an appropriate method from known methods such as a solution polymerization method and an interfacial polymerization method. In addition, the reaction conditions such as the polymerization catalyst at that time may be the same as conventional ones, and known methods can be used. The glass transition temperature of the polyester copolymer of the present invention is 100 ° C or higher, preferably 110 ° C or higher. When the glass transition temperature is less than 100 ° C, the thermal stability becomes poor and the use is limited. When molding an optical disk substrate from the polyester copolymer of the present invention, starting the raw material and the charging step, the polymerization reaction, the step of extruding the polymer into the refrigerant into pellets or sheets,
It is desirable to take care so that dust or the like does not enter during the process of drying and molding it. The cleanliness is usually less than 1000 for compact discs,
In the case of more advanced information recording, it is 100 or less.

The polyester copolymer of the present invention is useful as an optical disk substrate, an optical lens, a cover for a light source, or the like.
Although the intrinsic viscosity of the polyester varies depending on the conditions, it is preferably in the range of 0.4 or more and 0.8 or less, and more preferably 0.5 or more and 0.7 or less. This intrinsic viscosity is 0.4
If it is less than the above range, the strength of the molded product is weak and the product becomes brittle. On the other hand, when it exceeds 0.8, the molecules tend to be oriented and the birefringence after injection molding increases. An injection compression molding machine is usually well suited for molding the disk, and the mold surface temperature and the polymer temperature are particularly important in the molding conditions. Dicarboxylic acid component,
Types of glycol components, including dihydroxy compounds,
The mold surface temperature is preferably 20 ° C. or higher and 100 ° C. or lower, although it cannot be generally specified depending on the composition and the degree of polymerization, and
The polymer temperature at this time is preferably 250 ° C. or higher and 330 ° C. or lower. When the mold surface temperature is 20 ° C. or lower and the polymer temperature is 250 ° C. or lower, both the fluidity and transferability of the polymer are poor, and stress strain remains during injection molding,
It is uneconomical because the birefringence tends to increase and the molding cycle time also increases. When the mold temperature is 100 ° C. or higher, the transferability is good, but the mold is easily deformed at the time of release. Further, when the polymer temperature is 330 ° C. or higher, the polymer is apt to be decomposed, which causes a decrease in strength of the molded product and coloring.

[0014]

INDUSTRIAL APPLICABILITY As described above, the polyester copolymer of the present invention has excellent transparency, is excellent in moldability, heat resistance, dimensional stability and chemical resistance, and can provide an economically advantageous optical material. , Industrially useful. Further, the optical disk substrate made of this material has a small birefringence and is industrially useful.

[0015]

EXAMPLES The present invention will be specifically described with reference to the following examples. In the examples, "parts" means parts by weight. Further, the intrinsic viscosity, glass transition temperature, birefringence, total light transmittance and mechanical strength of the polymers in the examples were measured by the following methods. (1) Intrinsic Viscosity of Polymer Using a mixed solvent of phenol and tetrachloroethane (mixing ratio 60:40), it was dissolved at 80 ° C. and then measured in a 20 ° C. constant temperature bath. (2) Glass transition temperature of polymer It was determined by using about 10 mg of a sample in a differential scanning calorimeter (Rigaku Denki DSC-8230) and heating at a temperature rising rate of 10 ° C / min.

(3) Birefringence: 1.2 mm thick and 12 mm diameter molded by an injection compression molding machine.
The retardation at a position of 50 mm in the radial direction from the center of a 0 mm disk was measured with a polarization microscope manufactured by Carl Zeiss Inc. (Senermon, Berek, equipped with a Brace Keller compensator) with a 546 nm monochromatic light source. (4) Total Light Transmittance Using a disk substrate sample, measurement was carried out with a self-recording spectrophotometer (U-3400 manufactured by Hitachi) in the wavelength range of 400 to 900 nm, and the average value was shown. (5) Crack occurrence rate With respect to 100 disk substrate molded products, the center hole was observed with a microscope to find cracks and cracks caused by impact, and the occurrence rate was shown in%.

Example 1 100 parts of dimethyl 2,6-naphthalenedicarboxylate, 10 parts of dimethyl terephthalate, 33 parts of 1,1-bis (4-hydroxyethoxyphenyl) -1-phenylethane,
And 63 parts of ethylene glycol as a raw material and 0.1 part of calcium acetate as a catalyst. These are charged into a reaction tank and stirred at 190 ° C. to 230 ° C. according to a conventional method.
Transesterification was carried out by gradually heating to ° C. After extracting a predetermined amount of methanol out of the system, 0.03 parts of germanium oxide as a polymerization catalyst and 0.8 parts of triethyl phosphate for preventing coloring due to residual calcium acetate were added,
The temperature of the heating tank is 280 ° C and the degree of vacuum is 1To while gradually increasing the temperature and reducing the pressure and removing the generated ethylene glycol.
It was made to reach below rr. While maintaining this condition, waiting for the increase in viscosity, the reaction was terminated when the torque applied to the stirrer reached a predetermined value, and the mixture was extruded into water to obtain pellets. This polymer has an intrinsic viscosity of 0.58 and a glass transition temperature of 1.
It was 20 ° C. In addition, this pellet is vacuum dried by heating,
After adjusting the water content to 0.005% or less, the mold temperature is 70%.
℃, adjust the polymer temperature to 300 ℃, injection compression molding machine (Dynamelta M-25A II-DD
In M), a disc having a predetermined size was molded. This disc has a retardation of 12 nm and a total light transmittance of 9
It was 1%. The molded disk substrate had a crack occurrence rate of 0% and had excellent workability.

Example 2 Dimethyl 2,6-naphthalenedicarboxylate 8 as a raw material
4 parts, dimethyl terephthalate 17 parts, 1,1-bis (4
Example 1 using 33 parts of -hydroxyethoxyphenyl) -1-phenylethane and 53 parts of ethylene glycol.
Pellets were obtained in the same manner as in. This polymer had an intrinsic viscosity of 0.56 and a glass transition temperature of 115 ° C. The disc obtained by injection molding at a mold temperature of 65 ° C. and a polymer temperature of 290 ° C. had a retardation of 13 nm and a total light transmittance of 91%. As a result of microscopic examination of the molded disk substrate, the crack occurrence rate was 0%, which was good.

Examples 3 to 6 and Comparative Examples 1 to 3 After pellets were obtained in the same manner as in Example 1 except that the composition of the raw materials was changed, the mold temperature was 40 ° C to 100 ° C, and the polymer temperature was 2 ° C.
A disk was obtained by injection molding at 80 ° C to 300 ° C. The results of the polymer and disk analysis are shown in Table 1. From Table 1, the composition of the present invention of Comparative Example 1 has a low glass transition temperature and poor transparency. This adversely affects the thermal stability and transparency of the molded product, which is not preferable. Further, the disk has no cracks but has a relatively large warp. This is not preferable because it causes noise when reading signals and writing information after the product is manufactured. The non-invention products of Comparative Examples 2 and 3 have a sufficiently high glass transition temperature, a small retardation, and good transparency, but are very brittle, and thus cracks easily during molding, which is not preferable. However, as is clear from Examples 3 to 6, the polyester copolymer of the present invention is excellent in heat resistance, transparency and moldability, has high thermal stability and dimensional stability, and has a small birefringence. It can be seen that this is an excellent optical disk substrate.

[Table 1]

Claims (4)

[Claims] 1. A mixed composition of 2,6-naphthalenedicarboxylic acid or an ester-forming derivative thereof and terephthalic acid or an ester-forming derivative thereof, and a compound represented by the general formula (1): (Wherein R ₁ is an alkylene group having 2 to 4 carbon atoms, R ₂ is hydrogen or an alkyl group having 1 to 7 carbon atoms, an allyl group, an aralkyl group, R ₃ , R ₄ and R ₅ are hydrogen. Or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. L, m, n represent an integer of 1 or 2) and an aromatic ring is provided in the main chain and side chain. A substantially linear aromatic polyester copolymer comprising the dihydroxy compound and an aliphatic glycol having 2 to 4 carbon atoms. 2. A dihydroxy compound having an aromatic ring in the main chain and side chain represented by the general formula (1) is 1,1-bis (4
-Hydroxyethoxyphenyl) 1-phenylethane. 3. The polyester copolymer according to claim 1, wherein the aliphatic glycol is ethylene glycol. 4. A mixed composition of 2,6-naphthalenedicarboxylic acid or an ester-forming derivative thereof, terephthalic acid or an ester-forming derivative thereof, an aliphatic glycol, and a main chain represented by the following general formula (1): And a dihydroxy compound having an aromatic ring in the side chain are heated and stirred in the presence of a catalyst to perform an esterification reaction or a transesterification reaction,
Next, a method for producing a polyester copolymer molded article, which comprises subjecting the polyester copolymer to a further elevated temperature for polycondensation under high vacuum to perform molding. [Chemical 2] (In the formula, R _{1 to} R ₅ and l, m, and n are the same as above)