WO2009001987A1

WO2009001987A1 - Silicone-hydrogel compound for soft contact lens and soft contact lens produced using the compound

Info

Publication number: WO2009001987A1
Application number: PCT/KR2007/005098
Authority: WO
Inventors: Tack In Nam
Original assignee: Bescon.Co., Ltd.
Priority date: 2007-06-25
Filing date: 2007-10-18
Publication date: 2008-12-31
Also published as: JP2010531474A; RU2434899C2; CN101688042A; RU2009146491A; CA2686938C; AU2007355828A8; CA2686938A1; KR101231181B1; JP5432133B2; AU2007355828A1; UA92126C2; EP2170992A4; CN101688042B; KR20080113467A; EP2170992A1; AU2007355828B2

Abstract

The present invention relates to a silicone hydrogel composition for a soft contact lens and a soft contact lens using the same which comprises silicone N,O-bis(trimethylsilyl)acrylamide monomer and 2-hydroxyethyl methacrylate added with water soluble N-vinyl-2-pyrrolidone or N,N-dimethylacrylamide monoer to improve hydrophilic property and a cross-linking agent such as ethylene glyx>l dimethacrylate or divinyl benzene to provide a hydrophilic property, high water content rate, high oxygen permeability, good elongation and optical transmission.

Description

SILICONE-HYDROGEL COMPOUND FOR SOFT CONTACT LENS AND SOFT CONTACT LENS PRODUCED USING THE COMPOUND

Technical Field

[1] The present invention relate to a silicone -hydrogel soft contact lens, and more particularly, to a silicone-hydrogel composition for a soft contact lens including 2-hydroxyethyl methacrylate and N,O-bis(trimethylsilyl)acrylamide as a silicone monomer, and a soft contact lens using the same. Background Art

[2] Generally, a contact lens is classified into a hard lens having methyl metacrylate

(MMA) as a basic material and a soft lens including 2-hydroxyethyl methacrylate (HEMA) as a basic material wherein the soft lens has been increasingly used since it provides relatively higher oxygen permeability and a water content rate. This is possible since HEMA includes a hydroxyl group, a representative hydrophilic molecular structure, within a monomer and thus has a high water content rate unlike MMA (Refojo et., J. appl. Poly. Sd., 9:2425(1965)).

[3] Meanwhile, hydrogel refers to a cross-linking high molecule including much moisture in equilibrium and has a lot of physiological applications including medical high molecule for a contact lens (Reference: US. Patent No. 4300820).

[4] Currently, hydrogel used for lenses includes mostly 2-hydroxyethyl methacrylate as a monomer which is mixed with a small amount of a cross-linking agent and manufactured by a radical thermal polymerization. The lenses which are manufactured by the foregoing material have a water content rate of approximately 40% for properties of the material, are hydrophilic and soft to give a user less sense of a foreign matter and less pressure to the cornea when attached thereto. However, the lenses have weak mechanical strength and have a limited oxygen permeability of approximately 10Dk[IO cm /sec](m£ O mmHg)] and a limited wearing feeling, and protein is attached thereto if a user wears them for a long time (Wilson et al., Encyclo. Of Chem. Tech., 7: 192(1976); and US patent No. 6096138).

[5] As known in the art, the wearing feeling of the lens is closely related to the water content rate, and various attempts have been made to raise the water content rate. Some of the attempts have been commercialized. Specifically, an advanced product which has a water content rate of 80% and oxygen permeability of 40Dk[IO cm /sec] (mΑ O mmHg)] with a water-soluble monomer such as N-vinyl-2-pyrrolidone (NVP) and N,N-dimethylacrylamide (DMA) has been developed. However, the soft contact lens having the high water oontent rate easily dries and has a weak material to lower optical correction performance. A user may feel inconvenient when wearing and removing the lens. Thus, the contact lens having the high water content rate is mainly used as a one day disposable lens and inappropriate for long term use (Refojo. et al., Cont. & Intracular Lens Med. J., 1:36(1975)).

[6] Methacrylic high molecule which includes siloxane or fluorine and is used to manufacture RGP (rigid gas permeable) contact lens provides good wearing feeling and high oxygen permeability, and affects less to the cornea and is stable even though a hard material is used. Also, methacrylic high molecule triggers side effects such as corneal edema less than conventional polymethylmethacrylate (PMMA) does. However, siloxane or fluorine high molecule is a representative hydrophobic high molecule and is not wet by tears when applying to a contact lens. As RGB contact lens is hard and has an inherent shape, it may trigger some side effects or complications due to cornea distortion or difficulty in tear circulation. Also, the RGB contact lens has weak strength and is difficult to be manufactured, which results in high expenses and is easy to be contaminated or damaged when being worn.

[7] To tackle problems of the contact lens that is widely used, a soft contact lens

(silicone hydrogel soft contact lens) including hydrogel having good oxygen permeability with silicone has been started to be manufactured. Such a contact lens was released in the market for the first time in 1998, sharply increasing market share to approximately 150 million dollars in 2003 (Optician 2005).

[8] Silicone hydrogel is produced as a copolymer of a hydrophilic monomer such as

HEMA and a silicone containing monomer. General silicone monomers are very hydrophobic and difficult to maintain visibility due to separation of a phase when polymerized with a hydrophilic monomer such as HEMA To overcome such problem, a compatibilizer should be developed and used to improve compatibility between hydrophilic and hydrophobic monomers. PBVC (poly[dimethysiloxy]di[silylbutanol] bis[vinyl carbamate]), and a silicone macromer are used as a compatibilizer, which cost a lot of development expenses, and are difficult to manufacture lenses since they have a large molecular amount and high viscosity.

[9] Generally, silicone resin is hydrophobic and limitedly used in hydrogel type lenses since it lowers a water content rate. As a surface of the lenses is hydrophobic, the surface should be oxygen plasma treated to be hydrophilic through a post processing to thereby prevent a problem in wearing the lenses. There arises a problem that protein adheres to the surface of the lenses.

[10] Silicone hydrogel has a low elongation due to a property of the material and thus has low shape restoration of a contact lens. With increased hydrophobic property of the surface of the lens due to silicone, epithelial tissue of the cornea and the lenses are compatible with each other, and the lenses adhere to the cornea. Disclosure of Invention Technical Problem

[11] Accordingly, it is an aspect of the present invention to improve oxygen permeability of a contact lens by polymerizing a hydrophobic silicone monomer with a hydrophilic monomer to make the monomer hydrophilic.

[12] Also, it is another aspect of the present invention to provide a silicone hydrogel composition for a soft contact lens which includes water properly by adding N- vinyl-2-pyrrolidone (NVP>99%: Aldrich) or N,N-dimethylacrylamide (DMA, Aldrich), provides good optical transmission without a compatibilizer, and does not have a problem to be worn even without an additional surface treatment, and a soft contact lens using the same.

Technical Solution

[13] The foregoing and/or other aspects of the present invention can be achieved by providing a silicone hydrogel composition for a soft contact lens which comprises 2-hydroxyethyl methacrylate and silicone N,O-bis(trimethylsilyl)acrylamide) monomer represented by a following chemical formula 1.

[14] [Chemical Formula 1]

C¹⁵] H₂C=CH

C = O I N

(H ₃C)₃Si ^ ^-Ξι(CH₃)₃

[16] According to another aspect of the present invention, a content of

N,O-bis(trimethylsilyl)acrylamide) in the composition is 10 wt% and below.

[17] According to another aspect of the present invention, the composition comprises ethylene glycol dimethacrylate.

[18] According to another aspect of the present invention, a content of

N,O-bis(trimethylsilyl)acrylamide in the composition is 10 wt% and below, and a content of ethylene glycol dimethacrylate is 05 wt% and below. [19] According to another aspect of the present invention, the composition comprises divinyl benzene. [20] According to another aspect of the present invention, a content of

N,O-bis(trimethylsilyl)acrylamide in the composition is 10 wt% and below, and a content of divinyl benzene is 04 wt% and below. [21] According to another aspect of the present invention, the composition comprises one of N-vinyl-2-pyrrolidone and N,N-dimethylacrylamide. [22] According to another aspect of the present invention, a content of

N,O-bis(trimethylsilyl)acrylamide) is 5 wt% and below, a content of ethylene glyxtl dimethacrylate is 04 to 07 wt% and below and a content of N-vinyl-2-pyrrolidone is

45 wt% and below. [23] According to another aspect of the present invention, the composition comprises N- vinyl-2-pyrrolidone. [24] According to another aspect of the present invention, a content of

N,O-bis(trimethylsilyl)acrylamide is 5 wt% and below, a content of divinyl benzene is

03 to 05 wt% and below and a content of N-vinyl-2-pyrrolidone is 35 wt% and below.

[25] According to another aspect of the present invention, the composition comprises

N,N-dimethylacrylamide. [26] According to another aspect of the present invention, a content of

N,O-bis(trimethylsilyl)acrylamide is 5 wt% and below, a content of ethylene glyx>l dimethacrylate is 04 wt% and below and a content of N,N-dimethylacrylamide is 40 wt% and below. [27] According to another aspect of the present invention, the composition comprises

N,N-dimethylacrylamide. [28] According to another aspect of the present invention, a content of

04 wt% and below and a oontent of N,N-dimethylacrylamide is 30 wt% and below. [29] The foregoing and/or other aspects of the present invention can be achieved by providing a soft contact lens which is manufactured by the composition. Advantageous Effects

[30] As described above, silicone hydrogel composition for a soft contact lens and a soft contact lens using the same according to the present invention provides a contact lens which is directly attached to the eye to correct myopia, hypermetropia and astigmatism and adjust eyesight. The silicone hydrogel soft contact lens according to the present invention has hydrophilic property and high water content of 40 to 70%, high oxygen permeability of 50 to 100DK, good elongation of 200 to 400% and good optical transmission, secures healthy eyes, minimizes a sense of a foreign matter, a sense of dryness and pressure of the cornea to make a user feel comfortable. Also, the contact lens reduces rates of corneal edema or other illnesses.

[31] Further, the silicone hydrogel soft contact lens according to the present invention provides advantages of both oxygen permeable hard lens (RGP lens) having good oxygen permeability and a soft contact lens providing good wearing feeling to be wearable for consecutive two weeks to one month and tackle the problem of an existing lens being attached and detached every day.

[32] Additional aspects and advantages of the general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive ooncept. Best Mode for Carrying Out the Invention

[33] The present invention relates to a copolymer which is made by mixing

2-hydroxyethyl methacrylate (BISOMER HEMA ULTRA made by Cognis), a hydrophilic monomer as a main material, N,O-bis(trimethylsilyl)acrylamide (self synthesis) as a silicone monomer to improve oxygen permeability, N- vinyl-2-pyrrolidone (NVP>99%, made by Aldrich) or N,N-dimethylacrylamide (DMA made by Aldrich) water soluble monomer to raise hydrophilic property and ethylene glyool dimethacrylate (EGDMA>98%, made by Aldrich) or divinyl benzene (DVB> 80%, made by Aldrich) as a cross-linking agent in small amounts and then by a thermal polymerization of 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane) as a radical initiator. A copolymer is a long molecular structure in which small units called monomers are repeatedly linked to each other and includes a chemical linkage (three-dimensional structure) of those monomers.

[34] The contact lens was not particularly surface treated as it had a water content rate of

40 to 70% and was very hydrophilic. Here, a compatibilizer was not used. The contact lens is not weak and thus wearable for two weeks even though it has a high water content rate.

[35] Oxygen permeability was high, 50- 100Dk ([10 (cnf/sec)(m£ O mmHg)], and had no side effects, provided comfortable feeling and caused no problem for long term wear according to many clinical tests.

[36] The weak property of silicone hydrogel contact lens was improved and the result is as follows.

[37] Elongation was 200 to 400%, young modulus was 50 to 65 g/mnf, tensile strength was

80 to 110 g/mif and toughness was 120 to 145 g/mnf, which are very good for a contact lens. Mode for the Invention

[38] Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

[39] Exemplary embodiment 1

[40] Polymerization of N,O-bis(trimethylsilyl(acrylamide) and 2-hydroxyethyl methacrylate

[41] The amount of N,O-bis(trimethylsilyl)acrylamide is increased from 1Og to 9Og by adding 1Og each, and the amount of 2-hydroxyethyl methacrylate is decreased from 9Og to 1Og by reducing 1Og each to make a mixture. An initiator, 2,5-dimethyl 2,5-di(2-ethylhexanoylperoxy)hexane of QIg to Ig is dissolved to polymerize the mixture at 11O⁰C for 30 minutes.

[42] As a result, it was polymerized when the initiator of 02g (02 wt%) and above was used, regardless of the amount, but the initiator was not involved in transparency (compatibility). The mixture was cured by N,O-bis(trimethylsilyl)acrylamide of 1Og (10 wt%) and above, but had lower compatibility and became opaque milk color. The more N,O-bis(trimethylsilyl)acrylamide is used, the lower curability becomes. Thus, the polymer became soft.

[43] Preferably, an initiator of 02g (02 wt%) is used for polymerization. As

N,O-bis(trimethylsilyl)acrylamide has high degree of crosslink, the mixture is cured without a cross-linking agent. Compatibility (transparency) was good with 2-hydroxyethyl methacrylate and N,O-bis(trimethylsilyl)acrylamide monomer of 1Og (10 wt%).

[44] Exemplary embodiment 2

[45] Polymerization of N,O-bis(trimethylsilyl)acrylamide and N-vinyl-2-pyrrolidone

[46] The amount of N,O-bis(trimethylsilyl)acrylamide is increased from 1Og to 9Og by adding 1Og each, and the amount of N-vinyl-2-pyrrolidone is decreased from 9Og to 1Og by reducing 1Og each to make a mixture. An initiator, 2,5-dimethyl 2,5-di(2-ethylhexanoylperoxy)hexane, of QIg to Ig is dissolved to polymerize the mixture at 11O⁰C for 30 minutes.

[47] As a result, the mixture was not cured regardless of the amount of the initiator. The more N,O-bis(trimethylsilyl)acrylamide was used, the lower curability became. Thus, the mixture is not cured even when polymerized, and is sticky like an adhesive.

[48] In the present polymerization, even though N,O-bis(trimethylsilyl)acrylamide and a water soluble monomer, N-vinyl-2-pyrrolidone, are polymerized, the polymer was not cured. Thus, the mixture was not applicable for a lens and requires a cross-linking agent to be cured.

[49] Exemplary embodiment 3

[50] Polymerization of N,O-bis(trimethylsilyl)acrylamide, 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate

[51] The amount of N,O-bis(trimethylsilyl)acrylamide is increased from 1Og to 9Og by adding 5g each, and the amount of 2-hydroxyethyl methacrylate is decreased from 9Og to 1Og by redoing 5g each to make a mixture added with a cross-linking agent, ethylene glycol dimethacrylate, of Olg to Ig. An initiator, 2,5-dimethyl 2,5-di(2-ethylhexanoylperoxy)hexane of Q2g is dissolved to polymerize the mixture at HO⁰C for 30 minutes.

[52] As a result, with increase in ethylene glycol dimethacrylate, transparency

(compatibility) and curability improved but elongation became weaker. A polymer was obtained to be applicable to a lens by using ethylene glyool dimethacrylate of 05g (05 wt% and below). The polymer was cured by using N,O-bis(trimethylsilyl)acrylamide of 20 wt% and below and became transparent, but water absorption was not good after hydration for N,O-bis(trimethylsilyl)acrylamide of 10 wt% to 20 wt% and below. The polymer was transparently cured for 20 wt% and above, but became opaque and easily broken after hydration.

[53] In the present polymerization, use of the cross-linking agent, ethylene glycol dimethacrylate, improved degree of cross link and transparency (compatibility) and raised curability of the polymer and strength. It can be known that ethylene glycol dimethacrylate of 05 wt% is suitable for a lens.

[54] If N,O-bis(trimethylsilyl)acrylamide of 10 wt% and below, 2-hydroxyethyl methacrylate of 90 wt% and above and a cross-linking agent, ethylene glyool dimethacrylate, of 05 wt% and below are polymerized, compatibility improved and the polymer was transparently cured and had good hydration, which is applicable for a flexible lens to some extent.

[55] Exemplary embodiment 4 [56] Polymerization of N,O-bis(trimethylsilyl)acrylamide, 2-hydroxyethyl methacrylate and divinyl benzene

[57] The amount of N,O-bis(trimethylsilyl)acrylamide is increased from 1Og to 9Og by adding 5g each, and the amount of 2-hydroxyethyl methacrylate is decreased from 9Og to 5g by reducing 5g each to make a mixture added with a cross-linking agent, divinyl benzene, of QIg to Ig. An initiator, 2,5-dimethyl

2,5-di(2-ethylhexanoylperoxy)hexane of Q2g is dissolved to polymerize the mixture at HO⁰C for 30 minutes.

[58] As a result, with increase in divinyl benzene, transparency (compatibility) and curability improved but elongation became weaker. A polymer was obtained to be applicable to a lens by using divinyl benzene of 04g (04 wt%) and below. The polymer was cured by using N,O-bis(trimethylsilyl)acrylamide of 20 wt% and below and became transparent, but water absorption was not good after hydration for 10 wt% to 20 wt% and below. The hydration of the polymer was good for 10 wt% and below. For 20 wt% and above, the polymer was cured transparently, but became opaque and easily broken after hydration.

[59] In the present polymerization, use of the cross-linking agent, divinyl benzene, improved degree of cross link and transparency (compatibility) and raised curability of the polymer and strength. It can be known that divinyl benzene of 04 wt% and below is suitable for a lens.

[6D] If N,O-bis(trimethylsilyl)acrylamide of 10 wt% and below, 2-hydroxyethyl methacrylate of 90 wt% and above and a cross-linking agent, divinyl benzene, of 04 wt% and below are polymerized, compatibility improves and thus a polymer which is elongated and has good transparency and water absorption can be made.

[61] Compared to the exemplary embodiment 3, use of divinyl benzene is better for compatibility (transparency) than ethylene glyool dimethacrylate.

[62] Exemplary embodiment 5

[63] Polymerization of N,O-bis(trimethylsilyl)acrylamide, 2-hydroxyethyl methacrylate,

N-vinyl-2-pyrrolidone and ethylene glyool dimethacrylate

[64] The polymerization is performed by adjusting a water content rate of the polymer according to the exemplary embodiment 3 to improve hydrophilic property and by adding a water soluble monomer, N-vinyl-2-pyrrolidone, to check polymerization between the materials.

[65] The amount of N,O-bis(trimethylsilyl)acrylamide is increased from 5 wt% to 50 wt% by adding 5 wt% each, the amount of 2-hydroxyethyl methacrylate is decreased from 90 wt% by reducing 5 wt% each, and N-vinyl-2-pyrrolidone is increased from 5 wt% by adding 5 wt% each to make a mixture added with a cross-linking agent, ethylene glyool dimethacrylate, of Ql wt% to 1 wt%. An initiator, 2,5-dimethyl 2,5-di(2-ethylhexanoylperoxy)hexane of 02 wt% is dissolved to polymerize the mixture at 110⁰C for 30 minutes.

[66] As a result, with the cross-linking agent, ethylene glyool dimethacrylate, of 1 wt%, the polymer was cured by using N,O-bis(trimethylsilyl)acrylamide of 5 wt% to 10 wt%, 2-hydroxyethyl methacrylate of 50 wt% and below and N-vinyl-2-pyrrolidone of 40 wt% and above are polymerized to be cured transparently. However, the polymer was easily broken, and lost elongation and was easily torn after hydration. With the cross-linking agent of 04 wt% to 09 wt%, the polymer was cured by using N,O-bis(trimethylsilyl)acrylamide of 5 wt% and below, 2-hydroxyethyl methacrylate of 5 wt% to 90 wt% and below and N-vinyl-2-pyrrolidone of 5 wt% to 40 wt% and below are polymerized to be cured transparently. Particularly, the polymer using the cross-linking agent of 04 wt% to 07 wt% had good water absorption and elongation after hydration.

[67] If the amount of N-vinyl-2-pyrrolidone increases, a water content rate rises and compatibility between materials improves to thereby raise transparency. Compatibility was good with N-vinyl-2-pyrrolidone of 45 wt% and below, and a transparent polymer was obtained. Here, the water oontent rate was 38% to 55%. With N-vinyl-2-pyrrolidone of 45 wt% and above, a polymer having high water oontent rate of 55% and above was obtained.

[68] In the present polymerization, use of N,O-bis(trimethylsilyl)acrylamide of 5 wt% and below results in a polymer having good transparency, elongation and water absorption to be suitable for a lens.

[69] Use of the cross-linking agent, ethylene glyool dimethacrylate, raised a degree of cross link, improved transparency (compatibility) and curability of the polymer to make it strong. Elongation of the lens was lowered after hydration. Use of ethylene glyool dimethacrylate of 04 wt% to 07 wt% is appropriate for a lens.

[70] Increased use of N-vinyl-2-pyrrolidone improves compatibility between materials and transparency, but increases a water oontent rate and lowers elongation and tensile strength of the polymer. If N-vinyl-2-pyrrolidone of 45 wt% and below is used, a polymer having a water content rate of 38 wt% to 55 wt% is created to appropriate for a lens since it has good elongation and wettability.

[71] Exemplary embodiment 6 [72] Polymerization of N,O-bis(trimethylsilyl)acrylamide, 2-hydroxyethyl methacrylate,

N-vinyl-2-pyrrolidone and divinyl benzene

[73] The polymerization is performed by adjusting a water content rate of the polymer according to the exemplary embodiment 4 to improve hydrophilb property and by adding a water soluble monomer, N-vinyl-2-pyrrolidone, to check polymerization between the materials and by using divinyl benzene to be compared with ethylene glycol dimethacrylate as the cross-linking agent aα»rding to the exemplary embodiment 5.

[74] The amount of N,O-bis(trimethylsilyl)acrylamide is increased from 5 wt% to 50 wt% by adding 5 wt% each, the amount of 2-hydroxyethyl methacrylate is decreased from 90 wt% by reducing 5 wt% each, and N-vinyl-2-pyrrolidone is increased from 5 wt% by adding 5 wt% each to make a mixture added with a cross-linking agent, divinyl benzene, of Ql wt% to 1 wt%. An initiator, 2,5-dimethyl 2,5-di(2-ethylhexanoylperoxy)hexane of 02 wt% is dissolved to polymerize the mixture at 110⁰C for 30 minutes.

[75] As a result, with the cross-linking agent, divinyl benzene, of 1 wt%,

N,O-bis(trimethylsilyl)acrylamide of 5 wt% to 10 wt%, 2-hydroxyethyl methacrylate of 50 wt% to 90 wt% and below and N-vinyl-2-pyrrolidone of 10 wt% and above are polymerized to be cured transparently. However, the polymer was easily broken, and lost elongation and was easily torn after hydration. With the cross-linking agent of 04 wt% to 09 wt%, N,O-bis(trimethylsilyl)acrylamide of 5 wt% and below, 2-hydroxyethyl methacrylate of 5 wt% to 90 wt% and below and N- vinyl-2-pyrrolidone of 5 wt% to 40 wt% and below are polymerized to be cured transparently. Particularly, the polymer using the cross-linking agent of 04 wt% to 07 wt% had good water absorption and elongation after hydration.

[76] Increased use of N-vinyl-2-pyrrolidone improves compatibility between materials and transparency. If N-vinyl-2-pyrrolidone of 35 wt% and below is used, compatibility was good and a transparent polymer was obtained. Here, a water content rate was 38% to 55%. If N-vinyl-2-pyrrolidone of 35 wt% and above is used, a polymer having high water content rate of 55% and above was obtained.

[77] In the present polymerization, use of N,O-bis(trimethylsilyl)acrylamide of 5% and below results in a polymer having good transparency, elongation and water absorption to be suitable for a lens.

[78] Use of the cross-linking agent, divinyl benzene, further improves transparency

(compatibility) with higher degree of cross link than ethylene gljcol dimethacrylate according to the exemplary embodiment 5 and raises curability of the polymer to make it strong. Elongation of the lens was lowered after hydration. The size of the polymer was smaller than that using ethylene gljcol dimethacrylate. Use of divinyl benzene of 03 wt% to 05 wt% improves transparency and elongation of the polymer which is appropriate for a lens.

[79] Increased use of N-vinyl-2-pyrrolidone improves compatibility between materials and transparency, but lowers elongation and tensile strength of the polymer due to increase in a water content rate. If N-vinyl-2-pyrrolidone of 35 wt% and below is used, a polymer has a water content rate of 38% to 55%, and provides good transparency and elongation to be appropriate for a lens.

[80] Exemplary embodiment 7

[81] Polymerization of N,O-bis(trimethylsilyl)acrylamide, 2-hydroxyethyl methacrylate,

N,N-dimethylacrylamide and ethylene gljcol dimethacrylate

[82] The polymerization is performed by adjusting a water content rate of the polymer according to the exemplary embodiment 3 to improve hydrophilb property and by adding another water soluble monomer, N,N-dimethylacrylamide to check polymerization between the materials.

[83] N,O-bis(trimethylsilyl)acrylamide of 5wt% and below according to the result from the exemplary embodiment 5 is used, the amount of 2-hydroxyethyl methacrylate is decreased from 90 wt% by reducing 5 wt% each, and the amount of N,N-dimethylacrylamide is increased from 5 wt% by adding 5 wt% each to make a mixture added with a cross-linking agent, ethylene glycol dimethacrylate, of 04 wt%. An initiator, 2,5-dimethyl 2,5-di(2-ethylhexanoylperoxy)hexane of 02 wt% is dissolved to polymerize the mixture at 11O⁰C for 30 minutes.

[84] As a result, N,N-dimethylacrylamide of 40 wt% and above was compatible with

N,O-bis(trimethylsilyl)acrylamide of 5 wt% and became cured to generate a transparent polymer. A water oontent rate was 55% and above with a very high expansion rate. Increased use of N,N-dimethylacrylamide raised the water content rate and expansion rate, and improved compatibility between the materials and transparency.

[85] In the present polymerization, use of N,O-bis(trimethylsilyl)acrylamide of 5% and below results in a polymer having good transparency, elongation and water absorption to be suitable for a lens.

[86] Increased use of N,N-dimethylacrylamide improved compatibility between the materials and transparency, but triggered a very high expansion rate due to increase in the water oontent rate and lowered elongation and tensile strength of the polymer. If N,N-dimethylacrylamide of 40 wt% and above and 70 wt% and below is used, a polymer provides good transparency, water content rate and elongation to be appropriate for a lens.

[87] Exemplary embodiment 8

[88] Polymerization of N,O-bis(trimethylsilyl)acrylamide, 2-hydroxyethyl methacrylate,

N,N-dimethylacrylamide and divinyl benzene

[89] The polymerization is performed by adjusting a water oontent rate of the polymer according to the exemplary embodiment 4 to improve hydrophilic property, to check polymerization suitability between materials and to compare with the cross-linking agent, ethylene gljcol dimethacrylate, according to the exemplary embodiment 7.

[90] N,O-bis(trimethylsilyl)acrylamide of 5wt% and below according to the result from the exemplary embodiment 5 is used, the amount of 2-hydroxyethyl methacrylate is decreased from 90 wt% by reducing 5 wt% each, and the amount of N,N-dimethylacrylamide is increased from 5 wt% by adding 5 wt% each to make a mixture added with a cross-linking agent, divinyl benzene, of Q4 wt%. An initiator, 2,5-dimethyl 2,5-di(2-ethylhexanoylperoxy)hexane of 02 wt% is dissolved to polymerize the mixture at 11O⁰C for 30 minutes.

[91] As a result, N,N-dimethylacrylamide of 30 wt% and above was compatible with

[92] In the present polymerization, use of N,O-bis(trimethylsilyl)acrylamide of 5% and below results in a polymer having good transparency, elongation and water absorption to be suitable for a lens.

[93] Increased use of N,N-dimethylacrylamide improved compatibility between the materials and transparency, but triggered a very high expansion rate due to increase in the water content rate and lowered elongation and tensile strength of the polymer. If N,N-dimethylacrylamide of 30 wt% and above and 70 wt% and below is used, a polymer provides good transparency, water content rate and elongation to be appropriate for a lens.

[94] Compared to the exemplary embodiment 7, use of the cross-linking agent, divinyl benzene, improved compatibility (transparency) of the polymer more than ethylene glycol dimethacrylate does, but decreased elongation and had a smaller diameter.

[95] Exemplary embodiment 9

[96] Polymerization of N,O-bis(trimethylsilyl)acrylamide, 2-hydroxyethyl methacrylate,

N,N-dimethylacrylamide, N-vinyl-2-pyrrolidone and ethylene glycol dimethacrylate

[97] The polymerization is performed by adjusting a water content rate of the polymer according to the exemplary embodiment 4 to improve hydrophilb property and to check polymerization suitability between two materials of N,N-dimethylacrylamide and N-vinyl-2-pyrrolidone as water soluble monomers.

[98] N,O-bis(trimethylsilyl)acrylamide of 5 wt% and below according to the result from the exemplary embodiment 7 is used, 2-hydroxyethyl methacrylate of 60wt% is used and N,N-dimethylacrylamide and N-vinyl-2-pyrrolidone are changed properly within 40 wt% to make a mixture added with a cross-linking agent, ethylene glyool dimethacrylate, of 04 wt%. An initiator, 2,5-dimethyl

2,5-di(2-ethylhexanoylperoxy)hexane of 02 wt% is dissolved to polymerize the mixture at 110⁰C for 30 minutes.

[99] As a result, regardless of changes in N,N-dimethylacrylamide and N- vinyl-2-pyrrolidone, the mixture had good compatibility and generated a transparent polymer when cured, but it changed into a milk color by absorbing water.

[100] In the present polymerization, the mixture had good compatibility and generated a transparent polymer when cured, but it changed into a milk color by hydration, regardless of changes in N,N-dimethylacrylamide and N-vinyl-2-pyrrolidone. Thus, the polymer may not be used for a lens, and one of N,N-dimethylacrylamide and N- vinyl-2-pyrrolidone should be selected to use the polymer for a lens.

[101] Exemplary embodiment 10

[102] Polymerization of N,O-bis(trimethylsilyl)acrylamide, 2-hydroxyethyl methacrylate, N-vinyl-2-pyrrolidone, N,N-dimethylacrylamide and divinyl benzene

[103] The polymerization is performed by adjusting a water content rate of the polymer according to the exemplary embodiment 5 to check polymerization suitability between two materials of N,N-dimethylacrylamide and N-vinyl-2-pyrrolidone.

[104] With the result from the exemplary embodiment 8,

N,O-bis(trimethylsilyl)acrylamide of 5 wt% and 2-hydroxyethyl methacrylate of 63 wt% are used and N,N-diemthylacrylamide and N-vinyl-2-pyrrolidone are changed properly within 40 wt% to make a mixture added with a cross-linking agent, divinyl benzene, of Q4 wt%. An initiator, 2,5-dimethyl 2,5-di(2-ethylhexanoylperoxy)hexane of 02 wt% is dissolved to polymerize the mixture at 11O⁰C for 30 minutes. [105] As a result, regardless of changes in N,N-dimethyl£crylamide and N- vinyl-2-pyrrolidone, the mixture had good compatibility and generated a transparent polymer when cured, but it changed into a milk color by absorbing water.

[106] The polymerization according to the present embodiment has the same result as that according to the exemplary embodiment 9. The mixture had good compatibility and generated a transparent polymer when cured, but it changed into a milk color by hydration, regardless of changes in N,N-dimethylacrylamide and N- vinyl-2-pyrrolidone. Thus, the polymer may not be used for a lens, and one of N,N-dimethylacrylamide and N-vinyl-2-pyrrolidone should be selected to use the polymer for a lens.

[107] That is, the polymerization according to the present embodiment has the same result as that according to the exemplary embodiment 9.

[108] Exemplary embodiments 11 to 16 and Comparative embodiment 1

[109] Based on the results from the exemplary embodiments, according to exemplary embodiments 11 to 16, a soft contact lens was made by mixing 2-hydroxyethyl methacrylate, N,O-bis(trimethylsilyl)acrylamide and divinyl benzene (or ethylene glycol dimethacrylate), and N-vinyl-2-pyrrolidone or N,N-dimethylacrylamide. According to a comparative embodiment 1 , a contact lens was made by mixing 2-hydroxyethyl methacrylate, divinyl benzene as a cross-linking agent and 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane) as an initiator to thereby compare properties such as a water content rate, elongation rate, tensile strength and oxygen permeability.

[110] The oxygen permeability is a flow rate of oxygen transmitting a unit area of a contact lens material in a unit thickness, according to a unit pressure change. The method of measuring the oxygen permeability is as follows.

[I l l] A Dry a sample to be measured and a tool at the maximum.

[112] B. Mount a lens on a lower tool, and fix the lower tool by O-rings and then cover it with an upper tool by four screws not to leak gas.

[113] C. Make bubbles by soapy water of approximately 10% in an indicator.

[114] D. Connect a gas container with each line and operate a gas pressure sensor.

[115] E Purge each part with gas to be measured, for about two hours.

[116] F. Record time when the bubbles from the indicator started moving and the environmental factors at that time, and check and record the status at predetermined time intervals.

[117] G. Calculate by using a formula. [118] The formula is as follows.

area of sample x time taken for reference scale to me cm sec -⁽D

[120] Here, P, V and T refer to the status of the environment where the experiment is carried out. P' and T' refer to STP status and V is a value calculated according to the STP status.

^C121] _t , , _v ' I cmHSTή- cm - Permeability (DK) = = — ^ '- (2)

ΔPrαωi/rc cm sec-cmHa

[122] Here, I is an average thickness of the sample, Pressure has a value indicated by the pressure sensor. The value of the formula ® is substituted for the formula © to calculate permeability (DK).

[123] The water content rate is calculated commonly by dry- weight-basis representing moisture weight ratio to a dry weight of the sample as percent, but also by wet- weight-basis representing containing moisture ratio to a total weight including moisture as percent. However, there are made many definitions related to the water content rate such as "relative water content rate in saturated water content rate" or "equilibrium water content rate by relative humidity of surrounding air". Recently, volume water content rate representing containing moisture volume ratio to a total volume of the sample is also used in some cases.

[124] The moisture content of the contact lens is measured by using wet- weight-basis.

[125] The measuring method is as follows.

[126] A Hydrate the lens sufficiently (for about 24 hours and more).

[127] B. Remove water from the lens with a deer skin and measure a weight (M ).

[128] C. Dry the lens from an oven for at least 20 minutes and above (the point of time where the weight is not changed any more).

[129] D. Measure the weight of the dried lens (M ).

[130] E Measure the weight of at least ten sample lenses according to the processes of A to D and determine an average value as a water content rate.

[131] The formula is as follows.

^[132] M, - \U water content rate = — λ 100

M₁ [133] Exemplary embodiment 11: Manufacturing of contact lens 1:

[134] 2-hydroxyethyl methacrylate, N,O-bis(trimethylsilyl)acrylamide, N- vinyl-2-pyrrolidone and divinyl benzene (or ethylene gljcol dimethacrylate) [135] A mixture of 2-hydroxyethyl methacrylate of 643 wt% and above, N- vinyl-2-pyrrolidone of 30 wt% and below, N,O-bis(trimethylsilyl)acrylamide of 5 wt% and below, and divinyl benzene of 05 wt% and above (or ethylene gljcol dimethacrylate of 06 wt% and above) as a cross-linking agent is added with dissolved 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane) of 02 wt% and above as an initiator. The mixture was then injected to a mold manufactured with polypropylene (Casting Mold) and polymerized at 11O⁰C for 30 minutes to be cured. Then, the lens was separated from the mold to check compatibility (transparency). The lens was transparent, and the water content rate and the status were measured after hydration. [136] Exemplary embodiment 12: Manufacturing of contact lens 2: [137] 2-hydroxyethyl methacrylate, N,O-bis(trimethylsilyl)acrylamide, N- vinyl-2-pyrrolidone and divinyl benzene (or ethylene gljcol dimethacrylate) [138] A mixture of 2-hydroxyethyl methacrylate of 835 wt% and above, N- vinyl-2-pyrrolidone of 15 wt% and below, N,O-bis(trimethylsilyl)acrylamide of 1 wt% and below, and divinyl benzene of 03 wt% and above (or ethylene gljcol dimethacrylate of 04 wt% and above) as a cross-linking agent is added with dissolved 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane) of 02 wt% and above as an initiator. A lens was manufactured the same as that according to the exemplary embodiment 11 to evaluate properties.

[139] Exemplary embodiment 13: Manufacturing of contact lens 3: [140] 2-hydroxyethyl methacrylate, N,O-bis(trimethylsilyl)acrylamide, N- vinyl-2-pyrrolidone and divinyl benzene (or ethylene gljcol dimethacrylate) [141] A mixture of 2-hydroxyethyl methacrylate of 71.4 wt% and above, N- vinyl-2-pyrrolidone of 25 wt% and below, N,O-bis(trimethylsilyl)acrylamide of 3 wt% and below, and divinyl benzene of 04 wt% and above (or ethylene gljcol dimethacrylate of 05 wt% and above) as a cross-linking agent is added with dissolved 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane) of 02 wt% and above as an initiator. A lens was manufactured the same as that according to the exemplary embodiment 11 to evaluate properties.

[142] Exemplary embodiment 14: Manufacturing of contact lens 4: [143] 2-hydroxyethyl methacrylate, N,O-bis(trimethylsilyl)acrylamide, N- vinyl-2-pyrrolidone and divinyl benzene (or ethylene gljcol dimethacrylate) [144] A mixture of 2-hydroxyethyl methacrylate of 643 wt% and below, N- vinyl-2-pyrrolidone of 30 wt% and above, N,O-bis(trimethylsilyl)acrylamide of 5 wt% and below, and divinyl benzene of 05 wt% and above (or ethylene glyxil dimethacrylate of 06 wt% and above) as a cross-linking agent is added with dissolved 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane) of 02 wt% and above as an initiator. A lens was manufactured the same as that according to the exemplary embodiment 11 to evaluate properties.

[145] Exemplary embodiment 15: Manufacturing of contact lens 5: [146] 2-hydroxyethyl methacrylate, N,O-bis(trimethylsilyl)acrylamide, N- vinyl-2-pyrrolidone and divinyl benzene (or ethylene glycol dimethacrylate) [147] A mixture of 2-hydroxyethyl methacrylate of 65.4 wt% and below, N- vinyl-2-pyrrolidone of 30 wt% and above, N,O-bis(trimethylsilyl)acrylamide of 4 wt% and below, and divinyl benzene of 04 wt% and above (or ethylene glycol dimethacrylate of 05 wt% and above) as a cross-linking agent is added with dissolved 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane) of 02 wt% and above as an initiator. A lens was manufactured the same as that according to the exemplary embodiment 11 to evaluate properties.

[148] Exemplary embodiment 16: Manufacturing of contact lens 5: [149] 2-hydroxyethyl methacrylate, N,O-bis(trimethylsilyl)acrylamide,

N,N-dimethylacrylamide and divinyl benzene (or ethylene glycol dimethacrylate) [150] A mixture of 2-hydroxyethyl methacrylate of 66.4 wt% and below,

N,N-dimethylacrylamide of 30 wt% and above, N,O-bis(trimethylsilyl)acrylamide of Q3g, and divinyl benzene of 04 wt% and above (or ethylene glycol dimethacrylate of 05 wt% and above) as a cross-linking agent is added with dissolved 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane) of 02 wt% and above as an initiator. A lens was manufactured the same as that according to the exemplary embodiment 11 to evaluate properties.

[151] Comparative embodiment 1 : Manufacturing of contact lens [152] A mixture of 2-hydroxyethyl methacrylate of 9g and divinyl benzene of Ig as a cross-linking agent which are commonly used is added with dissolved 2,5-dimethyl-2,5-di(2-ethylhexanoyl peroxy)hexane) of (B2g as an initiator. The mixture was then injected to a mold manufactured with polypropylene (Casting Mold) and polymerized at 11O⁰C for 30 minutes to be cured. Then, the lens was separated from the mold to check a water content rate. According to the checking result, the lens

-11 2 had low water content rate of 38% and oxygen permeability of 10 to 20Dk[IO (an / sec)(m# O mmHg)].

[153] Table 1 [Table 1] [Table ]

[154] The properties of the contact lens which was manufactured with the foregoing content according to the exemplary embodiments and comparative embodiment are as follows.

[155] Table 2 [Table 2] [Table ]

[156] As shown in Table 2, the exemplary embodiments according to the present invention are hydrophilic, and have high water content rate of 40 to 70% and high oxygen permeability of 50 to 90Dk[IO (cm /sec)(m# O mmHg)], which are far better than those according to the comparative embodiment.

[157] Although a few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

[1] A silicone hydrogel composition for a soft contact lens which comprises

2-hydroxyethyl methacrylate and silicone N,O-bis(trimethylsilyl)a;rylamide) monomer represented by a following chemical formula 1. [Chemical Formula 1]

H₂C=CH

C = O I N

(H₃C)₃Si -^ ^Sι(CH ₃)₃

[2] The composition according to claim 1, wherein a content of

N,O-bis(trimethylsilyl)acrylamide in the composition is 10 wt% and below. [3] The composition according to claim 1, wherein the composition comprises ethylene glyx>l dimethacrylate. [4] The composition according to claim 1 , wherein the composition comprises divinyl benzene. [5] The composition according to claim 3, wherein the composition comprises one of N-vinyl-2-pyrrolidone and N,N-dimethylacrylamide. [6] The composition according to claim 4, wherein the composition comprises one of N-vinyl-2-pyrrolidone and N,N-dimethylacrylamide. [7] A soft contact lens which is manufactured by using the composition according to one of claims 1 to 6.