JP4802569B2 - Method for producing silicone monomer - Google Patents

Description

  The present invention relates to a silicone monomer suitable for use as a raw material for ophthalmic lenses such as contact lenses, intraocular lenses, and artificial corneas, and a method for producing a silicone monomer.

  Conventionally, a monomer containing a silicon group such as a siloxanyl group is known as an ophthalmic lens monomer.

  As one of such compounds, compounds represented by the above formula (c) or formula (c ′) are known (for example, Patent Document 1). Since this compound has a hydroxyl group in the molecule, it has a feature that compatibility with a hydrophilic monomer can be easily obtained, and the purity can be increased to 80% by weight or more by examining reaction conditions. However, it is difficult to completely consume the raw material epoxy silane, and it is also difficult to separate the epoxy silane, so that it remains in the monomer. This epoxy silane is a compound that is said to have a property of exuding when polymerized, and is also presumed to have irritation to eyes and the like. Thus, when this silicone monomer is used to form an ophthalmic lens, it may remain in the polymer, which may cause discomfort for the wearer. For this reason, there has been a strong demand for the development of a high-purity silicone monomer having as little epoxy silane content as possible, that is, preferably 50 ppm or less.

  As a method for reducing the content of this epoxy silane, there is a concept of giving priority to consumption of raw materials by increasing the reaction time. However, even in such a method, several hundred ppm of epoxysilane remains, and the purity is lowered due to the formation of by-products, and there is a concern about the influence of the by-products.

Patent Document 2 discloses a method of reacting a reaction product with acetic acid-methanol. However, even if this method is used, several hundred ppm of epoxysilane remains, which is not sufficient.
JP-A 56-22325 Example 4 JP, 2005-23011, A Example 1

  In view of the above problems, the present invention is based on the general formulas (a) and / or (a ′) in order to eliminate the possibility of deteriorating wearing feeling such as squeaking when used as a raw material for an ophthalmic lens. In the silicone monomer containing the silicone compound represented by the formula (1), a silicone monomer having a high purity of 80% by weight or more and a reduced content of epoxysilane contained therein, that is, a content of 50 ppm or less is provided. For the purpose.

In order to achieve the above object, the present invention has the following configuration. I.e., having the steps of reacting an epoxy silane and an unsaturated carboxylic acid represented by the following following general formula (a1), and performing processing by adding a strong acid to the reaction product, the formula (a) And / or a method for producing a silicone monomer, wherein the content of the silicone compound represented by (a ′) is 80% by weight or more and the content of the epoxysilane represented by the general formula (a1) is 50 ppm or less ,

(R ¹ represents an organic group having 1 to 20 carbon atoms including a polymerizable group. R ^{2 to} R ⁴ each independently represent hydrogen, an organic group having 1 to 20 carbon atoms, or —XA. R ⁵ to. R ⁷ independently represents hydrogen, an organic group having 1 to 20 carbon atoms, or —XA, X represents a divalent organic group having 1 to 20 carbon atoms, and A represents a siloxanyl group.
In other words, various preferred embodiments are proposed.

  Since the amount of epoxy silane contained in the silicone monomer according to the present invention is 50 ppm or less, polymerization is performed using this silicone monomer, and the polymer is further processed into an ophthalmic lens. It can be suitably used as a raw material for ophthalmic lenses such as contact lenses, intraocular lenses, and artificial corneas.

  The present inventors have intensively studied about the reduction of the epoxy silane remaining in the silicone monomer represented by the general formula (a) and / or (a ′), and caused a strong acid to act on the remaining epoxy silane in the silicone monomer. Thus, it has been found that the residual epoxysilane can be reduced to 50 ppm or less by converting to silicone diol. And when the silicone monomer having the epoxysilane content of 50 ppm or less was used, it was found that eye discomfort no longer occurs even for ophthalmic lenses such as contact lenses, and the present invention was completed.

  The silicone monomer of the present invention contains 80% by weight or more of a compound represented by the following general formula (a) and / or (a ′).

Wherein, R ¹ represents an organic group having 1 to 20 carbon atoms having a polymerizable group. Here, the polymerizable group represents an organic group capable of sequential polymerization such as chain polymerization such as radical polymerization and ionic polymerization, and polycondensation. Examples of R ¹ —COO— groups include acrylic acid groups, methacrylic acid groups, vinyloxyacetic acid groups, allyloxyacetic acid groups, crotonic acid groups, 2- (meth) acryloylpropanoic acid groups, and 3- (meth) acryloylbutanoic acid groups. Group, 4-vinylbenzoic acid group, 3-aminophthalic acid group, 3-hydroxyphthalic acid group and the like. This structure is simple to introduce derived from unsaturated carboxylic acid, and it is preferable that all of carboxylic acid, carboxylic acid salt, and carboxylic acid anhydride are available, so that acrylic acid group and methacrylic acid group are preferable. It is. X represents a divalent aliphatic or aromatic organic group having 1 to 20 carbon atoms. A represents a siloxanyl group. As the siloxanyl group, those represented by the following formula (b) are preferable from the viewpoint of availability of raw materials and ease of synthesis.

(A ^{1 to} A ¹¹ each independently represents hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. N represents an integer of 0 to 200; And c each independently represents an integer of 0 to 20, except when n = a = b = c = 0.)
Examples of groups A ^{1 to} A ¹¹ include hydrogen, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, t-butyl group, hexyl group, cyclohexyl group, 2- Examples thereof include alkyl groups such as ethylhexyl group and octyl group, and aryl groups such as phenyl group and naphthyl group. Further, a part of hydrogen may be substituted with a functional group not containing carbon, such as an amino group, a hydroxyl group, a thiol group, a nitro group, and a sulfonic acid group, and an ether group, a thioether group, and a sulfone group. The structure may contain a divalent or higher-valent group that does not contain carbon, such as a cyano group, a carboxyl group, an amide bond, a urea bond, or an ester within the range not departing from the total carbon number range. It may contain a carbon-containing atomic group such as a bond or a heterocyclic ring. Of these, the most preferred is a methyl group.

  In introducing the substituent represented by the formula (b), particularly preferred are tris (trimethylsiloxy) silyl groups and bis (trimethylsiloxy) since the raw materials for the introduction are industrially available at a relatively low cost. A methylsilyl group, a trimethylsiloxydimethylsilyl group, a polydimethylsiloxane group, a polymethylsiloxane group, a poly-co-methylsiloxane-dimethylsiloxane group, etc., and most preferred are tris (trimethylsiloxy) silyl group, bis (trimethyl) Siloxy) methylsilyl group and trimethylsiloxydimethylsilyl group.

R ^{2 to} R ⁴ each independently represent hydrogen or an organic group having 1 to 20 carbon atoms. The organic group may have, for example, a functional group not containing carbon such as amino group, hydroxyl group, thiol group, nitro group, and sulfonic acid group, and carbon such as ether group, thioether group, and sulfone group. The structure may contain a divalent or higher-valent group that does not contain carbon atoms, and within a range not departing from the total carbon number range, a cyano group, a carboxyl group, an amide bond, a urea bond, an ester bond, or a complex. It may contain a carbon-containing atomic group such as a ring.

  The compound represented by the general formula (a) and / or (a ′) of the present invention is simply a compound represented by the general formula (a1) (epoxysilane), an unsaturated carboxylic acid, preferably the above-mentioned preferred. It can be obtained by reacting an unsaturated carboxylic acid.

Here, R ^{5 to} R ⁷ each independently represent hydrogen, an organic group having 1 to 20 carbon atoms, or —X—A (in addition, the description of R ^{5 to} R ⁷ is the above general formula (a) or ( It is the same as the description of R ^{2 to} R ⁴ for the compound represented by a ′), and X and A also each of the compounds represented by the general formula (a) and / or (a ′) The same applies to the description of X and A).

  Such a silicone compound can be synthesized with reference to the aforementioned Japanese Patent Application Laid-Open No. 56-22325. After completion of the reaction, it is diluted with a solvent, washed with an alkali, dehydrated with a desiccant, and then the solvent is removed to obtain a crude silicone monomer.

  In the silicone monomer of the present invention, the purity of the silicone compound represented by the general formula (a) and / or (a ′) is 80% by weight or more, preferably 90% by weight or more. The crude silicone monomer can be purified by vacuum distillation or thin-film distillation, or by column purification. The upper limit of purity is not particularly limited, but is about 99% by weight in consideration of a loss in the purification process.

  In the silicone monomer of the present invention, the content of the epoxysilane represented by the general formula (a1) is 50 ppm or less, preferably 30 ppm or less, more preferably 20 ppm or less, and particularly preferably 10 ppm or less. When the amount of the epoxysilane is small, the possibility of unpleasant sensation in the eyes even when the ophthalmic lens is formed is reduced, and the ophthalmic lens having a good wearing feeling can be obtained. Although there is no limitation in particular as a minimum, when it considers economical efficiency, it is about 1 ppm.

  The epoxy silane represented by the general formula (a1) remains in the crude body from several hundred ppm to several thousand ppm, and the content thereof is set to 50 ppm or less. It is difficult for purification operations such as column separation. Therefore, the production method of the present invention includes a step of performing treatment by adding a strong acid to a reaction product of the compound represented by the general formula (a1) and the unsaturated carboxylic acid. In the present invention, a strong acid refers to an acid having a pKa of 3 or less, and examples of such an acid include hydrochloric acid, sulfuric acid, phosphoric acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, and the like. Among these, when trifluoroacetic acid is used, the hydrolysis of the epoxy silane represented by the general formula (a1) proceeds well, is easily converted into silicone diol, and the by-products are also reduced. Most preferably used.

  The conditions for the treatment with strong acid are not particularly limited, but when the above-mentioned trifluoroacetic acid is used, the temperature is preferably −80 ° C. to 150 ° C., considering the ease of operation, 20 ° C to 130 ° C is more preferable, and -20 ° C to 100 ° C is most preferable because thermal decomposition of the silicone compound can be suppressed. The processing time is suitably 1 to 5 hours.

  In addition, a solvent may be used to improve the affinity (compatibility), miscibility and fluidity between the crude product and the strong acid when the crude product of the silicone monomer is treated with a strong acid. But it doesn't matter.

  Next, in order to remove the added strong acid, the silicone diol produced by the treatment, etc., the treatment can be performed by adding a base to neutralize, and further washing with water or a basic aqueous solution.

  Furthermore, performing distillation purification and column purification on the silicone monomer thus obtained is preferably employed because it can remove impurities such as the generated silicone diol and improve the purity.

  The silicone monomer of the present invention is copolymerized with other polymerizable monomers and is suitably used for the production of ophthalmic lenses such as contact lenses, intraocular lenses, and artificial corneas.

  As a polymerization method, a known radical polymerization method or the like can be adopted. Also, in order to obtain an ophthalmic lens, a method of molding from the obtained polymer or a silicone monomer, a polymerization initiator, etc. are charged in the mold in advance. In this method, polymerization is carried out, followed by processing.

  Further, it is also possible to preferably employ a post-process such as further extraction processing of the obtained ophthalmic lens.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

Measurement Method 1 (Measurement of Silicone Monomer Purity, Gas Chromatography (GC))
GC-18A (FID detector) manufactured by Shimadzu Corporation and DB-5, 0.25 mm × 30 m × 1 μm (manufactured by J & W) were used for the capillary column. The carrier gas was helium (138 kPa), the inlet temperature was 280 ° C., the detector temperature was 280 ° C., and the temperature raising program was 60 ° C. (5 minutes) → 10 ° C./minute→325° C. (19 minutes). A sample was prepared by dissolving 100 μL of a measurement sample in 1 mL of isopropyl alcohol, and 1 μL was injected.

Measuring method 2 (Measurement of residual epoxysilane amount, gas chromatography mass spectrometer (GCMS))
Hewlett-Packard 5890 series II was used. The conditions were as follows.

Column: DB-WAX, 0.25 mm × 30 m × 0.25 μm (manufactured by J & W)
Temperature rising program: 50 ° C. (2 minutes hold) → 20 ° C./min→250° C. (2.5 minutes hold)
Inlet temperature: 250 ° C, detector temperature: 280 ° C
Carrier gas: helium (3.0 mL / min)
Injection volume: 2 μL
0.01 g of a sample was weighed into a 10 ml volumetric flask, and the volume was adjusted to 10 ml with acetone to obtain a measurement sample. A standard sample of epoxy silane was prepared by weighing 0.02 g of epoxy silane in a 100 ml volumetric flask and using a constant volume with acetone as a standard mother liquor. The measurement sample and each standard sample were measured by a selected ion detection method (SIM) using GCMS to obtain a chromatogram. The concentration of epoxysilane was calculated by a calibration curve method.

Example 1
A silicone compound represented by the following (c) and (c ′) synthesized with a reaction time of 15 to 20 hours by the method described in JP-A-56-22325 is diluted with hexane, and 0.5N sodium hydroxide is diluted. After washing with alkali and adding sodium sulfate and drying, the mixture was filtered and the solvent was distilled off with an evaporator. When the purity of the obtained silicone monomer crude product was measured, the purity of the silicone agent was 89.9%. It was 550 ppm when content of the epoxy silane in this silicone agent was measured.

  Next, 3 g of trifluoroacetic acid was added to 30 g of the crude silicone monomer, and the mixture was stirred at 50 ° C. for 2 hours. Next, 30 g of hexane was added and neutralized by adding 100 g of 10% sodium carbonate water at room temperature. Subsequently, the mixture was washed twice with 50 mL of 0.5 N aqueous sodium hydroxide solution and three times with 35 mL of 2.6% brine, dried by adding sodium sulfate to the organic layer, filtered, and the solvent was distilled off with an evaporator. The purity of the obtained silicone monomer was measured and found to be 89.4%. Moreover, when content of epoxysilane was measured, it was 20 ppm.

Example 2
Based on the method described in JP-A-2005-23011, 90 g of methanol and 15 g of acetic acid were added to 130 g of the crude silicone monomer obtained in Example 1, and the mixture was stirred at 22 ° C. for 30 minutes. After distilling off the solvent with an evaporator, 30 g of hexane was added, washed with 50 mL of 0.5N aqueous sodium hydroxide solution 5 times with 2.6 mL of sodium chloride solution 3 times, sodium sulfate was added to the organic layer and dried. the solvent was distilled off by an evaporator over filtered. The purity of the obtained silicone monomer was measured and found to be 91.8%. Moreover, when content of epoxysilane was measured, it was 500 ppm.

Next, 3 g of trifluoroacetic acid was added to 30 g of the crude silicone monomer, and the mixture was stirred at 50 ° C. for 2 hours. Next, 30 g of hexane was added and neutralized by adding 100 g of 10% sodium carbonate water at room temperature. Subsequently twice with 0.5N aqueous sodium hydroxide 50 mL, and washed 3 times with 2.6% saline 35 mL, dried by adding sodium sulfate to the organic layer, the solvent was distilled off by an evaporator over filtered. The purity of the obtained silicone monomer was measured and found to be 89.6%. Moreover, when content of epoxysilane was measured, it was 40 ppm.

Example 3
In Example 1, a silicone monomer was obtained in the same manner as in Example 1 except that the treatment condition of trifluoroacetic acid was changed to 25 ° C. for 2 hours. The resulting silicone monomer had a purity of 89.6% and an epoxysilane content of 40 ppm.

Example 4
In Example 1, a silicone monomer was obtained in the same manner as in Example 1 except that the amount of trifluoroacetic acid used was changed to 1 g. The resulting silicone monomer had a purity of 89.7% and an epoxysilane content of 40 ppm.

Comparative Example 4
A silicone monomer was obtained in the same manner as in Example 1 except that 3 g of phosphoric acid was used instead of trifluoroacetic acid. The resulting silicone monomer had a purity of 88.5% and an epoxysilane content of 50 ppm.
Comparative Example 1
6 g of activated carbon was added to 30 g of the crude silicone monomer obtained in Example 1, and the mixture was stirred at 22 ° C. for 30 minutes. After removing the activated carbon by filtration and distilling off the solvent with an evaporator, 30 g of hexane was added, washed 5 times with 50 mL of 0.5N aqueous sodium hydroxide solution and 3 times with 35 mL of 2.6% brine, and sulfuric acid was added to the organic layer. sodium dried was added and the solvent was distilled off by an evaporator over filtered. It was 380 ppm when content of the epoxy silane of the obtained silicone monomer was measured.

Comparative Example 2
A silicone monomer was obtained in the same manner as in Comparative Example 1 except that Kyoward 500 (adsorbent containing 38% magnesium oxide, manufactured by Kyowa Chemical Industry Co., Ltd.) was used instead of the activated carbon of Comparative Example 1. It was 400 ppm when content of the epoxy silane of the obtained silicone monomer was measured.

Comparative Example 3
In Example 1, a silicone monomer was obtained in the same manner as in Example 1 except that the reaction time was 30 hours. When the purity of the obtained silicone monomer crude product was measured, the purity of the silicone agent was 78.2%. The content of epoxysilane in the silicone agent was measured and found to be 114 ppm.

Claims (1)

The following general formula (a), which comprises a step of reacting an epoxysilane represented by the following general formula (a1) with an unsaturated carboxylic acid, and a step of performing treatment by adding trifluoroacetic acid to the reaction product And / or production of a silicone monomer in which the content of the silicone compound represented by (a ′) is 80% by weight or more and the content of the epoxysilane represented by the general formula (a1) is 40 ppm or less Method.

(R1 represents a C1-C20 organic group containing a polymerizable group. R2-R4 each independently represents hydrogen, a C1-C20 organic group, or -X-A. R5-R7 each independently. Represents hydrogen, an organic group having 1 to 20 carbon atoms, or -X-A. X represents a divalent organic group having 1 to 20 carbon atoms. A represents a siloxanyl group.)