JPH01201324A - Polyester copolymer for optical material - Google Patents

Abstract

PURPOSE:To obtain the title copolymer improved in refractive index, Abbe's number, transparency, etc., by constituting it from a specified acid component and a binary diol component. CONSTITUTION:The title polymer copolymer for optical materials is a polyester comprising an acid component comprising naphthalene-2,6-dicarboxylic acid and a glycol component comprising a binary system of 1,4-cyclo hexanedimethanol (A) (usually, one having a trans/cis ratio of 70/30) and ethylene glycol (C) and having an A to B molar ratio of 50/50<=A/B<=82/18 and a refractive index n>1.6 and an Abbe's number nu>30. By using this copolymer, a plastic lens excellent in colorlessness and transparency and low in molding stress can be produced. Said polyester can be produced by using a tran sesterification catalyst such as calcium acetate and a Ge-base polycondensation catalyst such as GeO2.

Description

[Detailed description of the invention] 11: Chigori ±1 The present invention is a new material suitable for optical components, optical elements such as eyeglass lenses, and in particular polyester having a high refractive index, a high Atsube number, and good transparency. Regarding copolymers.

Conventional technology and problem 3. Traditionally, inorganic glass (crown glass, flint glass, etc.) lenses have been used for glasses and microscope lenses, but in recent years, they have become lighter, easier to dye, more fashionable, and more popular.
Plastic lenses using organic polymers are also becoming popular from the standpoint of safety.

Currently, the mainstream plastic used for lenses is CR.
-39 (polymer of diethylene glycol bisallyl carbonate monomer), which has a smaller specific gravity than inorganic glass and can be lighter in weight, and is actually used in large quantities.

However, since CR-39 has a refractive index of about 1.5, there is a problem that the lens must be thick to achieve the same function as inorganic glass.

Therefore, in order to provide lenses that are light, thin, and have an R performance equivalent to that of inorganic glasses, organic polymers with high refractive indexes have been actively developed.
8341, JP-A-57-28118. Japanese Patent Publication No. 57-8
These techniques are disclosed in Japanese Patent Publication No. 5002 and Japanese Patent Publication No. 58-14449.

On the other hand, in addition to the high refractive index required for lenses to reduce weight and thickness, Atsbe's number is also considered to be an important factor for lens materials.

In other words, the larger the Atsube number, the smaller the dispersion (wavelength dependence of the refractive index), and as a result, the less chromatic aberration (a phenomenon in which the light that is bent by the lens due to light waves is redirected to another point). It will be of high quality.

However, in both inorganic glasses and organic polymers, materials with a high refractive index generally have a small Arahe number, and conversely, materials with a high Atsube number tend to have a low refractive index. There isn't much to be satisfied with.

The present inventor has already filed a patent application after discovering that polyethylene-2,6-naphthalene dicarboxylate (hereinafter abbreviated as PEN-2,6) has a high refractive index and is suitable for optical lenses. Ta.

This PEN-2,6 is crystalline and has the property of gradually crystallizing at high temperatures and decreasing transparency.

Therefore, it is necessary for optical materials to be modified to maintain this transparency. Furthermore, PEN-2 can also increase the Atsube number.
6 is also necessary.

That is, in order to use PEN-2 and PEN-6 as better quality lenses, it is necessary to improve the polymer so as to lower the crystallinity and improve the Abbe's number.

Generally, a method of copolymerizing a third component is known as a means for reducing crystallinity, and it is also known that alicyclic compounds tend to increase the Abbe number. (Polymer Digest: March 1986) Therefore, we investigated copolymerizing an alicyclic compound as a method to simultaneously satisfy both properties.

By the way, polyesters made of naphthalene dicarboxylic acid and alicyclic diol are known.

For example, in Dutch Patent No. 6,40,9,569, naphthalene-2,
By copolymerizing 2,7-isomer with 6-dicarboxylic acid, a crystalline to amorphous polymer with a high glass transition point is obtained.

In addition, U.S. Pat. Ta,
It is described that a polyester with good transparency can be obtained.

Further, U.S. Pat. No. 3,396,149 describes a polyester with improved dyeability, which is composed of naphthalene-2,6-dicarboxylic acid, cyclohexane dimetatool, and ethylene glycol.

All of these techniques are characterized in that they obtain polymers using Zn-3b catalysts, and are known to have problems with transparency, for example.

Further, US Pat. No. 3,522,215 discloses that a polyester consisting of naphthalene dicarboxylic acid and cyclohexanedimetatool is polymerized with a Ti catalyst and used for fiber and film applications.

However, none of these proposals consider optical applications, and therefore not only do they not mention refractive index, Atsube number, etc., but they also do not actually mention hue or colorlessness).
Also, in terms of transparency, it is unsatisfactory for use as an optical material.

An object of the present invention is to provide a naphthalate-based polyester copolymer for optical materials that has a high refractive index, a high Abbe number, and good transparency and 9 hues.

In the present invention, the acid component is naphthalene dicarboxylic acid obtained by performing transesterification in the presence of a Ca compound and polycondensation in the presence of a Ge compound.

The glycol component is a copolymer consisting of two components: (a) 1,4-cyclohexanedimethanol and (b) ethylene glycol, and has the formula <1) 0.5010.50≦A/B≦0.8210.18
...has a composition that satisfies (1) and has a refractive index n of 1
．． It is a polyester copolymer for optical materials with good transparency characterized by having an Abbe number ν of 6 or more and 30 or more.

In the present invention, the "calcium compound J" used as a transesterification catalyst in producing a polymer is
Examples include organic acid salts and carbonates.

Specifically, calcium acetate and calcium benzoate.

Examples include calcium carbonate. Among these, calcium acetate is particularly preferred; the amount of the calcium compound used is usually 50 to 15% based on the acid component constituting the polyester.
0 mmol (nuno l)%. Here, if necessary, add 1 to 10 ml of cobalt acetate as a color toner.
% may be added.

Magnesium compounds as transesterification catalysts.

When using a mankan compound, transparency is good, but
Colorlessness is slightly inferior to calcium, and melt heat stability during molding is low. Zinc compounds have poor hue (colorless property) and are inferior in transparency and melt heat stability. Furthermore, lithium compounds have comparatively good thermal stability, but have poor transparency and hue.

Examples of the "germanium compound" used as a polymerization catalyst in the present invention include oxides, organic acid salts, alkyl compounds, and aryl compounds. Specific examples include germanium oxide, germanium tetraacetate, germanium oxalate, germanium tartrate, and tetraphenylgermanium. Among these, germanium dioxide is particularly preferred. G
The amount of the compound e used is usually 10 to 100 nno1% based on the acid component constituting the polyester. When a Ti compound or an Sb compound is used, the hue of the polymer and molded product is poor, and the molded product is likely to be distorted.

However, in the case of Ca-Ge, surprisingly, no molding distortion occurs, although the reason is not clear, and the material has performance suitable for optical lenses. Furthermore, the compound used as the acid component "naphthalene dicarboxylic acid" is specifically a lower alkyl ester of naphthalene-2,6-dicarboxylic acid, and this lower alkyl ester is combined with ethylene glycol and 1 , 4-cyclohexanedimethanol using the catalyst shown above, followed by polycondensation to obtain the desired polymer.

Here, "lower alkyl" refers to an alkyl group having 1 to 4 carbon atoms, and it is essential to use 1,4-cyclohexanedimethanol as a copolymer. Even with alicyclic compounds, when cyclohexanediol is used, the transesterification reaction type 9 condensation reactivity is low and a polymer exhibiting satisfactory physical properties cannot be obtained.Also, with tricyclodecane dimetatool, polymerization proceeds sufficiently. However, the melting temperature stability is poor and the hue changes easily.

Note that 1,4-cyclohexanedimethanol has trans and cis isomers, but this ratio is arbitrary. Unless otherwise specified, the trans/cis ratio is 70/
Make a mixture with a ratio of about 30%.

1. The molar ratio (A/B') of 4-cyclohexanedimethanol and ethylene glycol in the polymer is 50/
It is necessary that 50≦A/B≦82/18.

And preferably 60/40≦A/B≦75/25
It is.

Further, a lens using a polymer obtained within this range has a high refractive index and a high Abbe's number, and is suitable as an optical lens.

When A/B<50150, the crystallization rate of the polymer is slow and it is close to an amorphous state, so when molded into a lens, although transparency is good, mechanical strength is insufficient. The effect of improving the heat retention number is not sufficient, and furthermore, the softening point is lower than that of the polymer in the range of formula (1), so the heat resistance is also lowered, and the deterioration due to retention during molding is increased.

On the other hand, in the case of A/B, the copolymer has properties similar to a homopolymer, so the crystallization rate is extremely high, and even if the polymer is rapidly cooled after polymerization, whitening due to crystallization will occur. , it loses its transparency and cannot be used as a plastic lens.

[Effects of the Invention] By using the polyester copolymer of the present invention, it is possible to create a plastic container with a high refractive index and a high Abbe number, as well as good colorlessness (hue) and transparency, and little molding distortion. Furthermore, since it has excellent heat resistance, continuous molding using an injection molding machine is possible, and it can be applied to optical materials that require heat resistance in addition to lens applications.

[Example] Hereinafter, the present invention will be specifically explained using Examples. In the examples, parts refer to parts by weight, and the refractive index Abbe's number, glycol component analysis in the polymer, [η], and melting point/softening point determination were measured using the following method and apparatus.

(1) Using a refractive index Atsube refractometer (Type T, manufactured by I Atago Co., Ltd.)
The refractive index at 0°C was measured, and a sulfur iodide methylene solution was used as the intermediate solution.

(2) At the same time as the Atsube number refractive index, use an Atsube refractometer to obtain the dispersion i, i (N N c ) at the same time as measuring the refractive index, and calculate from the formula [ ν”' (N 1 ) / (Nr Nc ). did.

(a. Seal the glycol component composition polymer sample with an appropriate amount of methanol,
After autoclaving at 250°C for 6 hours, quantify by gas chromatography.

(4) Intrinsic viscosity: 1.1.2,2, a value determined from the solution viscosity measured at 35°C''C'' in a 223 mixed solvent of -te1-lachloroethane and phenol.

(5) Melting point: 1 part m 910 Differentiat manufactured by ouDont
Scanning Cal.

rineter and 990Therial Anatu
Measured with zer.

(0 softening point: Sp Measured with a Thermo Mechanical Analyzer Model 942 manufactured by DuPont.

(7) Thermal stability: Δ[η] △ [η co − [η ] l − [η ] 2[η
]1: Polymer intrinsic viscosity before molding [η]2: Melting point +
It is calculated as the polymer intrinsic viscosity of a molded piece molded at a temperature of 10°C.

Shakyu Yu 2.33.5 parts of dimethyl 6-naphthalene dicarboxylate.

Using 17.3 parts of 1.4-cyclohexanedimethanol (abbreviated as CHDM) and 9.9 parts of ethylene glycol as raw materials, 0.02 part of calcium acetate (82,71io1%
).

After carrying out the transesterification reaction using 1.7×10 −3 parts of cobalt acetate (5Ilio1%) as a catalyst,
Subsequently, 0.01 part of germanium oxide (70u+o1
%) as a polymerization catalyst, and the intrinsic viscosity [
A polymer with η]=0.50 was obtained. The resulting polymer had a glycol component composition ratio A/B of 70/30 and a melting point of 293°C. From this polymer, a small injection molding machine manufactured by C3I MI NMAX and length (20 mm) x width (
The refractive index and Atsube number of the sample prepared using the refractive index measurement sample preparation mold were measured. The refractive index at this time is 1.64. Atsbe's number was 30.5. Further, the intrinsic viscosity [η] of the molded sample was 0.48, and there was almost no [77] loss due to molding.

In addition, this polymer was applied to the injection molding machine Klofner Company F-
Continuous molding was performed using convex lens molds for magnifying glass of 85 and φ60 with a cylinder temperature of 300°C5, a mold temperature of 30°C, and a cycle time of 70 seconds.As a result, there was no problem with continuous moldability. No coloring (colbf using Minolta color difference meter CR-100 and the attached standard white board)
fi was -1°0) A lens with good transparency could be obtained.

Actual Example 2.3 and Above Examples 1 to 10 When various compounds were used as catalysts in place of calcium acid and germanium dioxide in Example 1, and when the glycol component composition in the polymer was changed, the copolymerization component was further added. Tables 1 and 2 show the physical properties of each polymer and the physical properties of the molded product when changed.

Claims (1)

[Claims] 1. The acid component is naphthalene dicarboxylic acid, the glycol component is composed of two components, 1,4-cyclohexanedimethanol and ethylene glycol, and has a composition satisfying the following formula (1), and has a refractive index. Rate n is 1.6 or more, Abbe number ν
30 or more, a highly transparent polyester copolymer for optical elements. 0.50/0.50≦A/B≦0.82/0.18...
-(1) However, here A represents the mole fraction of 1,4-cyclohexanedimethanol, B represents the mole fraction of ethylene glycol, and A+B=1.0. 2. The polyester copolymer for optical elements according to claim 1, which is obtained by carrying out a transesterification reaction in the presence of a calcium compound and carrying out a polycondensation reaction in the presence of a germanium compound.