JPS61152708A - Production of polymer - Google Patents

Abstract

PURPOSE:To produce a polymer having excellent transparency, moldability, heat-resistance and moisture absorption-resistance, and suitable as a material for optical element having low birefringence and high reciprocal dispersion, by polymerizing a specific unsaturated carboxylic acid ester. CONSTITUTION:Preferably 100-5(wt)% unsaturated carboxylic acid ester of formula (R is H or CH3; n is 0 or 1) and preferably 0-95% other polymerizable unsaturated monomer (e.g. methyl acrylate, styrene, etc.) are polymerized usually in the presence of a polymerization initiator such as benzoyl peroxide at 50-120 deg.C in a solvent such as benzene.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a polymer. More specifically, the present invention relates to a method for producing a polymer that is excellent in transparency, moldability, heat resistance, and moisture absorption resistance, has low birefringence, and has a high inverse dispersion rate and is suitable as an optical element material.

(Prior Art) Polymethyl methacrylate, polystyrene, polycarbonate resins, etc. have been known as transparent thermoplastic resins, especially resins for optical elements, but there is no transparent resin that satisfies all of the 111 required properties. The current situation is that it is not found at the moment.

For example, polymethyl methacrylate is transparent.

Although it is a relatively excellent material with excellent low birefringence and a high inverse dispersion rate, it has a problem of being prone to dimensional changes during use because of its extremely high hygroscopicity.

Polystyrene resin has very low hygroscopicity.

It has large birefringence, and its transparency tends to change over time.
It is unsuitable as a material for optical elements.

Further, polycarbonate resin has very excellent heat resistance and excellent moisture absorption, but has large birefringence and somewhat poor transparency.

Furthermore, polystyrene and polycarbonate have a low rate of inverse dispersion (1) when used, for example, in optical lens systems.

It is difficult to use it as a master lens, which controls the performance of an optical system. p Among these resins, many attempts have been made to improve the hygroscopicity of polymethyl methacrylate resin, which has particularly high potential for optical applications.

For example, JP-A-58-5318, JP-A-58-5
No. 354, JP-A-58-11515, JP-A-58-13652, JP-A-59-122,509, etc. disclose that cyclohexyl methacrylate, benzyl methacrylate, and higher alkyl methacrylate are added to methyl methacrylate. Methods such as copolymerization have been proposed.

(Problems to be Solved by the Invention) Although these methods of improving the hygroscopicity of polymethyl methacrylate resin do improve the hygroscopicity,
It is still not sufficient as a material for optical elements, and there is also the problem that heat resistance is significantly reduced.

(Means for Solving the Problems) That is, the present invention relates to a method for producing a polymer characterized by polymerizing an unsaturated carboxylic acid ester represented by the general formula (I).

(However, in formula 2, R is hydrogen or methyl group, n is 0 or 1
) The method for producing the polymer according to the present invention includes copolymerizing one or more unsaturated carboxylic acid esters represented by the general formula (I) with other polymerizable unsaturated monomers. Also included.

In the present invention, each of the unsaturated carboxylic acid esters represented by the general formula (I) can be polymerized alone, and ? Two or more types of C can be copolymerized. Moreover, these can be used alone or in combination of two or more, and furthermore, other polymerizable unsaturated monomers that can be copolymerized with these can be blended and copolymerized.

Here, other polymerizable unsaturated monomers include unsaturated fatty acid esters, aromatic vinyl compounds, vinyl cyanide compounds, and N-substituted maleimides. Examples of unsaturated fatty acid esters include methyl acrylate, ethyl acrylate,
Butyl acrylate.

Acrylic acid alkyl esters such as 2-ethylhexyl acrylate and stearyl acrylate, cyclohexyl acrylate, tricyclo acrylate (5,2,1,0"=
']] Decal-8-yl acrylic acid.

Aromatic acrylic esters such as chloroalkyl esters, phenyl acrylate, and benzyl acrylate.

Acrylic acid esters such as glycidyl acrylate.

Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, and cyclohexyl methacrylate.

methacrylic acid cycloalkyl esters such as methacrylic acid tricyclo[5,2,1,0''.6]dec-8-yl;

Examples include aromatic methacrylic esters such as phenyl methacrylate and benzyl methacrylate, and methacrylic esters such as glycidyl methacrylate.

Examples of the aromatic vinyl compound include styrene, α-substituted styrene such as α-methylstyrene and α-ethylstyrene, and nuclear-substituted styrene such as chlorostyrene, vinyltoluene, and t-butylstyrene. Examples of vinyl cyanide compounds include acrylonitrile and metacyclonitrile. Examples of N-substituted maleimide include N-methylmaleimide, N-ethylmaleimide, and N-inclovirmaleimide.

Aliphatic N-substituted maleimides such as N-butylmaleimide and N-laurylmaleimide; alicyclic N-substituted maleimides such as N-Schif-lohexylmaleimide;

Examples include aromatic N-substituted maleimides such as N-phenylmaleimide, N-methylphenylmaleimide, N-chlorophenylmaleimide, and N-methoxyphenylmaleimide.

Excellent transparency, moldability, heat resistance and moisture absorption resistance.

In order to obtain a polymer with low birefringence and high inverse dispersion, the polymerizable monomers used are preferably blended in the following manner.

Namely.

Other polymerizable unsaturated monomers are blended in an amount of 0 to 95% by weight. If the amount of unsaturated carboxylic acid ester represented by general formula (I) is too small, it will be difficult to sufficiently achieve or improve the above-mentioned properties.

As a method for producing the polymer of the present invention, known methods such as radical polymerization and ionic polymerization can be applied. For example, it can be produced by methods such as bulk polymerization, solution polymerization, and suspension polymerization in the presence of a 1-polymer initiator. Polymerization methods are preferred.

Examples of initiators used in the polymerization include benzoyl peroxide, lauroyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanony), 1,1-di-t- Organic peroxides such as butylperoxy-3,3,5-)limethylcyclohexane, azobisisobutyronitrile, azobis-4
-Azo compounds such as methoxy-2,4-cymervaleronitrile, azobiscyclohexanone-1-carbonitrile, azodibenzoyl, water-soluble catalysts such as potassium persulfate and ammonium persulfate, and peroxides or persulfuric acids. Any catalyst that can be used in normal radical polymerization, such as a redox catalyst using a combination of a salt and a reducing agent, can be used. The polymerization catalyst is 0.01 to 10% of the total amount of monomers.
Preferably, it is used in a range of % by weight. Mercaptan compounds, thioglycol, carbon tetrabromide as polymerization regulators.

α-methylstyrene dimer or the like may be added as necessary to adjust the molecular weight.

The polymerization temperature is preferably selected appropriately between 0 and 200°C, particularly preferably 50 and 120°C.

Solvents for solution polymerization include benzene, toluene,
Xylene, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, dichloroethylene, etc. can be used.

Suspension polymerization is carried out in an aqueous medium, with the addition of suspending agents and, if necessary, suspension aids. Suspending agents include water-soluble polymers such as polyvinyl alcohol, methylcellulose, and polyacrylamide, and sparingly soluble inorganic substances such as calcium phosphate and magnesium pyrophosphate. It is preferable to use 0.03 to 1% by weight of the heavy and poorly soluble inorganic material based on the total amount of monomers.

As a suspending agent, an anionic surfactant such as sodium dodecylbenzenesulfonate may be used. When a sparingly soluble inorganic substance is used as a suspending agent, it is preferable to use it in combination. The suspension aid is preferably used in an amount of 0.001 to 0.02% by weight based on the total amount of monomers.

The unsaturated carboxylic acid ester compound represented by the general formula (I) used in the present invention can be obtained using a generally known method for synthesizing methacrylic esters or acrylic esters.

Norbornyl methacrylate or norbornyl acrylate with J1=Q in the general formula (■) is an example of adding Id, i-ruhornene KHsO, or adding formic acid, acetic acid, etc., and then converting norborneol obtained by hydrolysis to methacrylic acid or acrylic acid. Obtained by acid esterification. Esterification can be carried out by a condensation reaction between norborneol and methacrylic acid, acrylic acid, methacrylic acid chloride, or acrylic acid chloride, or a transesterification reaction with methyl methacrylate, methyl acrylate, or ethyl acrylate.

In general formula (I), when n is 1, it represents norbornylmethyl methacrylate or norbornylmethyl acrylate, which can be synthesized by, for example, K as follows. 5
-Norbornene-2-methanol is subjected to a catalytic hydrogenation reaction to give norbornylmethanol, and this is made into a methacrylic ester, t or acrylic ester in the same manner as described above.

The monomer obtained by the present invention can be used for molding as a transparent resin. Especially as a material for optical elements for still cameras and video cameras.

Lenses for telescopes, eyeglasses, contact lenses, sunlight gathering, etc., prisms such as pentaprisms, mirrors such as concave mirrors, polygons, and optical fibers.

It can be applied to optical connectors, optical conductive elements such as optical waveguides, optical disks such as audio disks and computer information file disks, light emitting diodes, compensators, etc.

When using the polymer obtained by the present invention, consideration should be given to preventing deterioration of the polymer and improving molding processability, antioxidants such as phenolic, thioether, and phosphite, lubricants, antistatic agents, and ultraviolet absorbers. Agents and the like may be added as necessary. Also.

In use, various coating films such as magnesium heptadide can be applied to the surface of the molded polymer in order to prevent ghosting due to light reflection.

(effect) The polymer obtained by the present invention is transparent and moldable.

It has excellent heat resistance and moisture absorption resistance, low birefringence, and high inverse dispersion.

This is thought to be mainly due to the alicyclic and -applied norbornane skeleton.

(Example) Next, examples of the present invention will be shown.

Examples 1 to 6 and Reference Example 1 Into an Erlenmeyer flask equipped with a three-way stopcock, 100 parts by weight of monomers having the composition shown in Table 1, 0.4 parts by weight of lauroyl peroxide, and 0.2 parts by weight of n-dodecyl mercaptan were added and mixed.・After dissolving and replacing the inside of the flask with nitrogen gas,
The mixture was immersed in a constant temperature water bath at 60° C. while stirring and shaking, and polymerized for 30 minutes under a nitrogen stream to obtain a partially polymerized product. Subsequently, this partially polymerized product was injected into a glass cell and polymerized at 60°C for 4 hours, and then at 100°C for 5 hours to obtain a transparent sheet-like polymer. The total light transmittance, saturated water absorption, refractive index, and Atsube number of this polymer were measured.

After dissolving this polymer 1009 in tetrahydrofuray 2009, this solution was poured into methanol 51 under stirring to precipitate a bipolymer, which was separated from P and dried to obtain a white powdery polymer. The glass transition point of this polymer was measured. The above results are summarized in Table 1.

The characteristics were evaluated using the following method.

Light transmittance (ch): ASTM D-1003 saturated absorption f
L index (S): ASTM D570 refractive index, Atsbe number:
Atsube refractometer (manufactured by Elma Optical ■) K, Yoshi measurement Glass transition temperature Tg ('C): Differential scanning calorimeter (DSC)
) Measurement Examples 7 to 14 and Reference Examples 2 to 5 Ingredient l Ingredient ■ In the reaction vessel, put Ingredient 1. After charging component (1) and replacing the atmosphere in the reaction vessel with nitrogen gas while mixing and stirring, polymerization was carried out at 60°C for 2 hours and at 98°C for 4 hours. The polymerization rate at this time was 99%. The polymerized particles were filtered, pickled, washed with water, dried, and then made into pellets using an extruder and used as samples for characteristic evaluation. The results are shown in Table 2.

Examples 15 to 20 and Reference Example 6 Except that the monomers in the formulation shown in Table 3 were used.

It was carried out according to Example 7. The results are shown in Table 3.

(effect) Polymer transparency and moldability obtained by the present invention.

It has excellent heat resistance and moisture absorption resistance, low birefringence, and can increase the inverse dispersion rate.

（・〜　、(・′

Claims (1)

[Claims] 1. A method for producing a polymer, which comprises polymerizing an unsaturated carboxylic acid ester represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (However, in the formula, R is hydrogen or methyl group, n is 0 or 1
2. Production of the polymer according to claim 1, which involves polymerizing one or more unsaturated carboxylic acid esters represented by the general formula (I) and other polymerizable unsaturated monomers. Method.