JPH10120646A - Production of pentaerythritol ester of mercaptocarboxylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pentaerythritol ester of a mercaptocarboxylic acid which is a monomer capable of preventing undesirable releases of urethane-based plastic lenses from a mold and generation of minute voids in them. SOLUTION: This pentaerythritol ester of a mercaptocarboxylic acid is produced by reacting pentaerythritol containing <=5wt.% of bispentaerythritol with a mercaptocarboxylic acid in the presence of a catalyst. Urethane-base plastic lenses are obtained by reacting the obtained opentaerythritol ester of the mercaptocarboxylic acid with an iso(thio)cyanate compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pentaerythritol mercaptocarboxylate and a method for producing the same, and a urethane plastic lens obtained by reacting the pentaerythritol mercaptocarboxylate with an iso (thio) cyanate compound.

[0002]

2. Description of the Related Art Urethane resins are tougher and more transparent than other resins.
In recent years, plastic lenses have been manufactured. Accordingly, proposals regarding urethane-based plastic lenses have been actively made, and the present inventors have also made various proposals regarding plastic lenses using this polyurethane resin (Japanese Patent Publication No. 4-58488, Japanese Patent Publication No. 4-58488).
-58489, JP-A-63-46213).

[0003] Among these urethane-based plastic lens resins, the most typical resin is a resin obtained by reacting pentaerythritol mercaptocarboxylic acid ester with an iso (thio) cyanate compound, and is colorless, transparent and highly refractive. It has low dispersion and is the best resin for plastic lens with excellent impact, dyeability, workability, etc.

[0006] Pentaerythritol mercaptocarboxylic acid ester is a so-called direct esterification method in which ordinary polyhydric alcohol and mercaptocarboxylic acid are removed in the presence of an esterification catalyst while distilling off by-product water out of the system (Japanese Patent Publication No. 39-9071).

[0005] The purity of pentaerythritol, which is the raw material of this ester compound, is about 90% by weight with ordinary industrial chemicals.
And contains several types of impurities. Among the major impurities, bispentaerythritol, a formalin bimolecular condensate of pentaerythritol, and dipentaerythritol, a dehydrated dimer of pentaerythritol,
Kinds are mentioned, and approximately 3 to 8% by weight and 2 to 5% by weight are contained.

In general, a plastic lens is manufactured by injecting a monomer mixture into a mold composed of two glass molds and a resin gasket or tape, followed by heat polymerization.

[Problems to be solved by the invention]

However, the production of a plastic lens in which pentaerythritol mercaptocarboxylate is reacted with an iso (thio) cyanate compound is different from the production of a general-purpose plastic lens obtained by polymerizing diethylene glycol bis (allyl carbonate).
In some cases, problems such as difficulty in releasing from the mold after polymerization and difficulty in generating extremely fine bubbles inside the obtained lens may occur.

The problem of releasability leads to breakage of an expensive glass mold, and the problem of air bubbles leads to a decrease in lens yield. In other words, these problems have been troublesome to increase the cost of the plastic lens.

[0009]

Means for Solving the Problems In view of such problems, the present inventors have conducted intensive studies and as a result, have found that poor release and fine bubbles are caused by the monomer pentaerythritol mercaptocarboxylate. I found it. As a result of further intensive studies, surprisingly, the use of pentaerythritol mercaptocarboxylate produced from pentaerythritol having a bispentaerythritol content of not more than a specific amount surprisingly solves the above problem. The present inventors have found that the plastic lens can be manufactured economically, and have reached the present invention.

That is, the present invention provides a pentaerythritol mercaptocarboxylic acid ester obtained by reacting pentaerythritol having a content of impurities of bispentaerythritol of 5% by weight or less with mercaptocarboxylic acid in the presence of an acid catalyst, and a process for producing the same. And a urethane-based plastic lens obtained by reacting the pentaerythritol mercaptocarboxylic acid ester with an iso (thio) cyanate compound.

The purity of pentaerythritol as a raw material of the ester compound of the present invention is not limited at all by the purity and the content of dipentaerythritol, but is limited only by the content of bispentaerythritol. That is, pentaerythritol having a bispentaerythritol content of 5% by weight or less is preferred, and those exceeding 5% by weight are not preferred because the problems of mold releasability and bubbles may occur.

[0012] The other raw material, mercaptocarboxylic acid, is a compound having one or more mercapto groups and one or more carboxyl groups in one molecule, and is not particularly limited in quality. It is preferably used. Specific examples include thioglycolic acid, thiolactic acid, 3-mercaptopropionic acid, thiomalic acid, thiosalicylic acid, and the like, but the present invention is not limited to only these listed compounds. These may be used alone or two or more of them may be reacted with pentaerythritol.

Examples of the esterification catalyst for reacting pentaerythritol with mercaptocarboxylic acid include mineral acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and alumina, and p-toluenesulfonic acid, benzenesulfonic acid, trichloroacetic acid, dibutyltin oxide and the like. Acid catalysts typified by organic acids are preferably used. Even if no catalyst is added, the reaction proceeds, but the reaction rate is slower than when a catalyst is used, and the reaction tends to take a long time. On the other hand, in the case of a basic catalyst, the reaction solution tends to be easily colored, and in some cases, a more detailed study than the acid catalyst is required in determining the type and amount of the catalyst. I can not say.

In the production of pentaerythritol mercaptocarboxylate, the use of an azeotropic agent is not an essential condition, but a method of using an azeotropic agent to continuously remove by-produced water from the system by heating under reflux. General. Examples of commonly used azeotropic agents include, for example, benzene, toluene, xylene, nitrobenzene, chlorolobenzene, dichlorolobenzene, anisole, diphenyl ether, methylene chloride, chloroform, dichloroethane and the like. These may be used as a mixture of two or more kinds, or may be used as a mixture with another solvent.

The pentaerythritol mercaptocarboxylate of the present invention obtained by the above-mentioned method includes, for example, the following compounds. Pentaerythritol thioglycolate, pentaerythritol-
3-mercaptopropionate, pentaerythritol thiolactate, pentaerythritol thiosalicylate, and the like. The ester compound of the present invention is not limited only to these listed compounds. Further, these ester compounds may be compounds in which the hydroxyl group is completely esterified or compounds in which only a part of the hydroxyl group is esterified. Further, a mixture thereof may be used. These ester compounds are 2
You may mix and use more than one kind.

The iso (thio) cyanate compound of the present invention is a compound having at least one iso (thio) cyanato group in one molecule. Specifically, for example, xylylenediiso (thio) cyanate, trimethylhexamethylenediiso (thio) cyanate, hexamethylenediiso (thio) cyanate, isophoronediiso (thio) cyanate, bis (iso (thio) cyanate Cyclohexyl) methane, bis (iso (thio) cyanatomethyl) cyclohexane, 2,5-bis (isocyanatomethyl) -1,4-
Examples thereof include dithiane, 2,5-diisocyanato-1,4-dithiolane, bis (isocyanatomethyl) disulphide, and their isocyanurates, burettes, carbodiimides, and the like. The iso (thio) cyanate compound of the present invention is not limited to only these listed compounds. These may be used as a mixture of two or more.

The plastic lens of the present invention is obtained by reacting a pentaerythritol mercaptocarboxylic acid ester produced from limited pentaerythritol with an iso (thio) cyanate compound. The usage ratio of at least one or more of these ester compounds and at least one or more of the iso (thio) cyanate compounds is SH group / NC
O group = 0.3-2.0, preferably 0.7-2.
It is in the range of 0.

For the purpose of improving the physical properties, operability, polymerization reactivity and the like of the plastic lens of the present invention, besides ester compounds and iso (thio) cyanates forming urethane resins, amines and the like are also typical. Other active hydrogen compounds, epoxy compounds, olefin compounds, carbonate compounds, ester compounds, metals, metal oxides, organometallic compounds, inorganic substances and the like, other than the urethane-forming raw material, or two or more may be added.

The production of the plastic lens of the present invention is usually carried out as follows. Mix and defoam the ester compound, iso (thio) cyanate compound and, if necessary, a third monomer such as an olefin compound, and inject the homogeneous mixture into a mold consisting of a glass mold and a resin gasket or tape. I do. This mold is heated and / or
Alternatively, the resin lens is formed by UV irradiation, and the plastic lens is taken out.

The plastic lens obtained by the present invention is subjected to surface polishing, antistatic treatment, hard coat treatment, and anti-reflection coat treatment in order to improve anti-reflection, anti-fogging or fashionability as required. ,staining,
Physical or chemical treatment such as dimming treatment, painting with a colorant or a transparent surface protective agent can be performed.

[0021]

The present invention will be described below in more detail with reference to examples and comparative examples. In these examples, “parts” means “parts by weight”. The obtained plastic lens was evaluated by the following method.

Refractive index and Abbe number: Measured at 20 ° C. using a Pulrich refractometer. Release evaluation: 10 plastic lenses were manufactured.
A case where there was no breakage or cracking of the mold was evaluated as (（), and other cases were evaluated as (X). Bubble evaluation: The plastic lens was observed with a microscope of 100 times magnification.

Example 1 650 parts (4.2 mol) of pentaerythritol, p-toluenesulfonic acid were placed in a five-necked reaction flask equipped with a stirrer, a reflux cooling water separator, an N ₂ gas purge tube, and a thermometer. -19 parts of monohydrate, 900 ml of toluene, and 1000 ml of water were charged at room temperature. The charged pentaerythritol had a purity of 89.6% by weight, and contained 4.7% by weight of dipentaerythritol and 5.4% by weight of bispentaerythritol. (Hydrolysis of bispentaerythritol) This reaction flask was heated to reflux (internal temperature of 87 to 89 ° C.) under an N ₂ atmosphere and maintained for 2 hours.
Hydrolysis of bispentaerythritol was performed. When the reaction solution was analyzed by HPLC, the purity of pentaerythritol was 93.7% by weight, dipentaerythritol was 4.7% by weight, and bispentaerythritol was 1.0% by weight. (Synthesis of ester compound) Next, 1982 parts (18.5 mol) of 3-mercaptopropionic acid was added, and further, while heating and refluxing, water and by-produced water were continuously drawn out of the system. Time (internal temperature 104-121 ° C)
Cooled to room temperature. The amount of water withdrawn from the system after subtracting the charged water was 96.6% of the theoretically generated water.
The reaction solution is washed with a base and water, and after removing toluene and a trace amount of water under reduced pressure under heating, the solution is filtered to obtain 2122 parts of pentaerythritol-3-mercaptopropionate (hereinafter abbreviated as PEMP). . PE obtained
The APHA of MP was 10, and the SHV was 7.91 eq / g. (Production of plastic lens) PEMP113 obtained
Parts, 87 parts of m-xylylene diisocyanate, 0.010 parts of dimethyltin dichloride, 0.010 parts of dimethylcyclohexylamine, and 0.18 part of dioctyl phosphoric acid under reduced pressure to prepare a uniform monomer mixture. did. This mixture is poured into a mold composed of a glass mold and a resin gasket,
Polymerization was carried out by heating for an hour, and the plastic lens was taken out after cooling. Table 1 shows the results.

Example 2 4.7% by weight of dipentaerythritol, 3.3% by weight of bispentaerythritol and 91.7% by weight of pentaerythritol were used in the same manner as in Example 1 without hydrolysis. The test was performed. Table 1 shows the results.

Example 3 The same procedure as in Example 1 was carried out using 4.5% by weight of dipentaerythritol, 4.7% by weight of bispentaerythritol and 90.7% by weight of pentaerythritol without hydrolysis. The test was performed. Table 1 shows the results.

Example 4 Dipentaerythritol 5.0% by weight, bispentaerythritol 5.0% by weight, purity 89.6% by weight using pentaerythritol without hydrolysis as in Example 1 The test was performed. Table 1 shows the results.

Comparative Example 1 Example 1 was carried out without hydrolyzing bispentaerythritol. Table 1 shows the results.

COMPARATIVE EXAMPLE 2 2.2% by weight of dipentaerythritol, 7.8% by weight of bispentaerythritol, and 89.7% by weight of pentaerythritol using pentaerythritol as in Example 1 without hydrolysis. The test was performed. Table 1 shows the results.

Example 5 The same procedure as in Example 1 was carried out using 2.2% by weight of dipentaerythritol, 4.3% by weight of bispentaerythritol and 93.2% by weight of pentaerythritol without hydrolysis. The test was performed. Table 1 shows the results.

Example 6 The same procedure as in Example 1 was carried out using 5.2% by weight of dipentaerythritol, 3.6% by weight of bispentaerythritol and 90.9% by weight of pentaerythritol without hydrolysis. The test was performed. Table 1 shows the results.

Example 7 Using 8.9% by weight of pentaerythritol, 0.5% by weight of bispentaerythritol and 90.3% by weight of dipentaerythritol in the same manner as in Example 1 without hydrolysis. The test was performed. Table 1 shows the results.

Example 8 A test was conducted in the same manner as in Example 1 except that thioglycolic acid was used instead of mercaptopropionic acid. The obtained ester compound was pentaerythritol thioglycolate. Table 2 shows the results.

Comparative Example 3 A test was conducted in the same manner as in Example 8 except that pentaerythritol was not hydrolyzed. Table 2 shows the results.

Example 9 A test was conducted in the same manner as in Example 1 except that thiolactic acid was used instead of mercaptopropionic acid. The obtained ester compound was pentaerythritol thiolactate.
Table 2 shows the results.

Comparative Example 4 A test was conducted in the same manner as in Example 9 except that pentaerythritol was not hydrolyzed. Table 2 shows the results.

[0036]

[Table 1]

[0037]

[Table 2]

Example 10 56 parts of PEMP of Example 1, 20 parts of m-xylylene diisocyanate, 26 parts of ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate 1
0 parts, dimethyltin dichloride 0.11 parts (0.1%),
2-hydroxy-2-methyl-1-phenylpropane-
1-one 1.1 parts (1.0%), t-butylferroxy (2-ethylhexanoate) 0.11 part (0.1%)
Was degassed under reduced pressure to prepare a uniform monomer mixture. This mixed solution was poured into a mold composed of a glass and a resin gasket, and after UV irradiation, heated and cured, and a plastic lens was taken out. Table 3 shows the results.

Comparative Example 5 The test of Example 10 was performed using the PEMP of Comparative Example 1. Table 3 shows the results.

[0040]

[Table 3]

[0041]

According to the present invention, a high-quality urethane-based plastic lens having excellent releasability and no bubbles can be produced more economically.

Claims (3)

[Claims] 1. A bispentaerythritol content of 5
A method for producing pentaerythritol mercaptocarboxylate by reacting pentaerythritol in an amount of not more than 5% by weight with mercaptocarboxylic acid in the presence of an acid catalyst. 2. A pentaerythritol mercaptocarboxylic acid ester obtained by the method according to claim 1. 3. A urethane plastic lens obtained by reacting the pentaerythritol mercaptocarboxylate according to claim 2 with an iso (thio) cyanate compound.