JP2634698B2 - Method for reducing tackiness of soft acrylic polymers - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for reducing the tackiness of certain soft acrylic polymers. The invention is particularly useful for ophthalmic lenses made from such soft acrylic polymers, especially for foldable intraocular lenses.

Intraocular lenses have been known since about 1950. They are,
It is used to replace the natural lens of the eye that has been damaged by a disease such as trauma or cataract. A typical intraocular lens (10L) is an artificial lens ("opti
c) ") and at least one support member (" haptic ") for positioning 10L in the eye. Visual part is polymethyl methacrylate (PMMA)
And can be rigid, relatively flexible, or even completely deformable, and the 10L can be rolled or folded, including:
And allows it to be inserted into the eye through a relatively small incision. The tactile part is generally polypropylene or
Manufactured from a resilient material such as PMMA. 10L
May have either a “one-part” or “multi-part” design. The so-called multi-part lens is that the sight and haptic (one or more) are manufactured separately,
Subsequently, the tactile part is provided to the visual part. In a one-piece lens, the optic and haptics are formed from a one-piece material and, depending on the material, the haptics are then cut or lathed from the material to produce 10L.

EP 485 197 A1 (published May 13, 1992) has a high refractive index, is flexible and transparent, can be inserted into the eye through a relatively small incision, and One type of soft acrylic polymer is disclosed that is suitable for forming a 10 L that recovers its original shape. This type of lens material is effective in that thinner lenses can be crafted (10L is folded and allows for the use of smaller incisions), but this type of lens is
In addition to handling equipment, it has been found to have a tendency to adhere to itself. In fact, the inserted 10L may take several minutes to separate from itself after insertion. A tacky lens requires the surgeon to perform more operations and increases the operating time (due to the operations and the longer time to open the fold). Lenses with reduced surface tack can be more easily manipulated during implantation procedures. A lens with reduced surface tackiness, as a final result, facilitates 10L placement, reduces operative time, and increases patient safety.

Both chemically non-reactive and chemically reactive plasmas have been used for several years to treat various polymer surfaces. For example, Inagak
i et al., "Adhesion of glow discharge polymers to metals and polymers", Journal of Applied Polymer Science , 26: 333.
3-3341 (1981), and Inagaki et al., Capacitive (Capaci
tively) Distribution of polymer precipitation during glow discharge polymerization in coupling systems ", Journal of Applied Polymer Sci
ence , 26: 3425-3433 (1981). Furthermore, plasma treatment has recently been used for treating silicone contact lenses and silicone intraocular lenses. For example, Ho et al., "Ultra-thin coating of plasma polymer of methane applied to the surface of silicone contact lenses", Jornal of Biomedical Materials Research , 22:
919-937 (1988); Hettlich et al., "Plasma-Induced Surface Modification on Silicone Intraocular Lenses: Chemical Analysis and In Vitro Characterization", Biomaterials , 12: 521-52.
4 (1991); and Tidwell, CD, "Surface Modified,
Development of Self-passivating Intraocular Lens ", Master's Thesis, University of Washington (1990).

Plasma treatments have been used to modify other types of polymer surfaces, but to the applicant's knowledge, plasma treatments have traditionally been used to reduce the tackiness of soft acrylic polymer surfaces. Absent.

SUMMARY OF THE INVENTION Surprisingly, it has been found that plasma treatment of the polymer surface of articles made from soft acrylic polymers greatly reduces the stickiness often associated with such articles.

The method of the present invention provides that the article to be treated
o frequency (RF) placed in a plasma reactor and treated with plasma. Plasma is
It can be formed from inert gases or organic molecules. Conditions for forming a stable plasma vary from reactor to reactor. The processing parameters adjusted to create the plasma include gas type, power, pressure, flow rate, time,
And temperature. Factors that vary from reactor to reactor and can affect plasma processing conditions include reactor chamber geometry / volume (barrel, cuboid or cube volume) electrode type / geometry / plane spacing, RF power / frequency, gas Flow / pump system. Other factors affecting processing are the material being processed, the loading density of the sample and the fixturing.

DETAILED DESCRIPTION OF THE INVENTION The method of the present invention may be applied to anything made from a soft acrylic polymer that has an inherent tack in air or flowing media, where such tack is not desired. The method of the present invention is preferably utilized for a monomer having the following formula, and a modified soft acrylic polymer that can be formed from a crosslinking monomer: Wherein: X is H or CH _3; m is an 0; Y is no, 0, S, or NR, wherein, R represents, H, CH
_{3, C n H 2n + 1} (n = 1~10), iso _{-OC 3 H 7, C 6 H} 5, or be a CH ₂ C ₆ H _5; Ar is an aromatic ring such as benzene, the aromatic ring can be unsubstituted, or _{H, CH 3, C 2 H} 5, n-C
₃ H _7, iso _{-C 3 H 7, OCH 3,} C 6 H 11, Cl, Br, C 6 H 5, or
It is substituted with CH ₂ C ₆ H _5; and crosslinking monomers have a plurality of polymerizable ethylenically unsaturated groups.

European Patent Publication No. 485 published May 13, 1992
No. 197 A1 (the “197 application”) discloses methods for preparing these soft acrylic polymers and describes these polymers in great detail; therefore, they are further described herein. I will not do it. Further, the '197 application discloses a method for forming 10 L from these polymers. The entire contents of the '197 application are incorporated herein by reference.

While not intending to be bound by any particular theory, Applicants believe that reducing the tack of these soft acrylic articles by plasma treatment with an inert gas involves three primary mechanisms: 1 The impact of ionic or charged particles on the extended polymer chains on the 10L surface is due to the clipped chains.
(Pendant chemical groups have been physically removed by ion bombardment of the polymer surface), giving a smoother surface. Thus, when the 10L contacts either itself or another surface (eg, a device), the entanglement of these chains is reduced.

2) During the generation of the plasma, short wavelength UV is also radiated, which, under high vacuum, promotes increased surface cross-linking of the polymer structure. This denser cross-linking of the polymer surface contributes and reduces the tackiness of the surface.

3) Increasing the surface polymer network structure gives surfaces with both increased polarity and wetting properties (ie, more hydrophilic surfaces);
It has been shown to have a major effect on the adhesive properties of soft acrylic when immersed in water.

When reactive molecules are used in the processing of soft acrylic,
The primary mechanism of tack reduction is a function of the properties of the particular polymer and the particular gas plasma. For example,
With methane gas treatment, the treated polymer is not only highly hydrophobic, but also very highly crosslinked, giving a smooth and dense surface. The surface minimizes the possibility of surface interaction (ie, chain entanglement).

Depending on the type of plasma used, the reduced stickiness may be due to the treated article being present in an aqueous medium (eg, in water, saline, or aqueous bodily fluids), or when the article is wet (polymeric). (If water remains on the surface). For example, the 10 L stickiness decreases only in aqueous media when argon gas plasma is used, but decreases in air as well as aqueous media when methane gas plasma is used.

Plasma chambers suitable for use in the present invention are commercially available (eg, Advanced Plasma Systems, Inc.
(St. Petersburg, Florida), GaSonics / IPS, Inc. (Hay
ward, California), Plasma Science, Inc. (Forster C
ity, California), and Advanced Surface Technolo
gy, Inc. (from Billerica, Massachusetts). Particularly useful plasma chambers are Advanced Plasma Systems,
B-Serie available from Inc. ("Advanced Plasma")
s Plasma System. Fixtures for goods and / or
Or a holder may be desired to ensure uniform surface treatment; such fixtures and holders are also available from Advanced Plasma.

The article to be treated, if necessary or desired, is placed in a suitable fixture and mounted in a plasma chamber. The chamber is evacuated, then gas is introduced into the chamber and adjusted to the desired pressure. Next, the power of the RF power generator is turned on. A plasma is formed in the chamber and processes the article at the desired time. After processing is completed, the RF power generator is turned off and the article is removed from the chamber.

Processing conditions for plasma treatment of soft acrylic articles can vary depending on the type of plasma and reactor specifications. Generally, types of plasma useful in the present invention include inert gases such as argon and helium (and mixtures thereof), and reactive gases such as various hydrocarbons (eg, methane). In the treatment of 10 L of soft acrylic, it is preferable to use argon plasma. In argon plasma processing, the preferred range of processing conditions (using a cubic reactor with primary electrodes) is as follows; power = 300-400
Watts; pressure = 150-225 mTorr; and time = 3-5 minutes. These settings are only approximate and may vary somewhat depending on the particular reactor chamber used.

The following examples are presented to illustrate further various aspects of the present invention, and are not intended to limit the scope of the invention in any way.

Example 1 The following is an example of a typical procedure for argon plasma treatment of a soft acrylic optic.

The lens holder and plasma chamber are first cleaned with oxygen plasma by procedures well known to those skilled in the art. The optic to be treated is mounted on a lens holder and the lens holder is placed in a plasma chamber. The chamber is then sealed and evacuated. Argon gas is pumped into the chamber until the pressure reaches 160 mTorr ("mTorr"). Next, the power of the RF power generator is turned on to 400 watts, the power is maintained for 5 minutes, and then the power is turned off. The gas is allowed to flow for 5 minutes after the power generator has been turned off, then the chamber is purged with argon gas and the vacuum is returned to atmospheric pressure. The sample is then removed from the chamber.

Example 2 In another typical example of argon plasma treatment of the soft acrylic optic, the chamber was filled with argon gas at a pressure of 225 mTorr and power was applied at 300 watts for 3 minutes. Followed the procedure.

Example 3 A typical procedure for methane plasma treatment of the soft acrylic optics follows the procedure of Example 1 except that the chamber was filled with methane gas at a pressure of 50 mTorr and power was applied at 50 watts for 10 minutes. Was.

The present invention has been described with reference to certain preferred embodiments; however, the present invention may be embodied in other specific forms or modifications without departing from its spirit or essential characteristics. The above-described embodiments are considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Piper, Barbara A. Texas 76116, USA, Fort Worth, Number 320, Liverpool Court 3329 (56) References JP-A-2-84444 (JP, A) JP-A-59-24825 (JP, A) JP-A-3-286832 (JP, A) JP-A-59-71336 (JP, A)

Claims (16)

(57) [Claims] 1. A method for reducing the tackiness of a soft acrylic article, comprising: placing the soft acrylic article to be treated in a high frequency plasma reactor; closing the reactor chamber, Reducing the pressure to substantially zero; introducing a plasma gas into the reactor chamber and adjusting the pressure; generating a plasma in the reactor chamber using a high frequency power generator; and the soft acrylic Treating the soft acrylic article for a time sufficient to remove tackiness on the surface of the article. 2. The method of claim 1, wherein said plasma gas is selected from the group consisting of an inert gas and a hydrocarbon. 3. The plasma gas is selected from the group consisting of argon, helium, and mixtures thereof.
The method according to claim 2. 4. The plasma gas contains argon.
The method of claim 3. 5. The method according to claim 1, wherein the plasma gas contains helium.
The method of claim 3. 6. The method according to claim 3, wherein said plasma gas contains a mixture of argon and helium. 7. The method of claim 2, wherein said plasma gas contains methane. 8. The method of claim 1, wherein the soft acrylic article is placed in a suitable fixture before being placed in the reactor chamber. 9. The soft acrylic article is an intraocular lens, and the suitable fixture is a lens holder.
The method according to claim 8. 10. The method of claim 9, wherein said plasma gas is selected from the group consisting of an inert gas. 11. The plasma gas is selected from the group consisting of argon, helium, and mixtures thereof.
The method according to claim 10. 12. The method of claim 11, wherein said plasma gas contains argon. 13. The plasma gas contains methane.
The method according to claim 9. 14. A method for reducing the tackiness of a soft acrylic intraocular lens, comprising the steps of: placing the intraocular lens in a lens holder; placing the intraocular lens and the lens holder in a high frequency plasma reactor. Disposing; closing the reactor chamber and reducing the pressure in the chamber to substantially zero; introducing argon gas into the reactor chamber and adjusting the pressure; using a high frequency power generator Generating a plasma in the plasma chamber; and treating the intraocular lens for a time sufficient to remove tackiness of the surface of the intraocular lens. 15. The method of claim 14, wherein said plasma reactor is a cubic reactor having a primary electrode. 16. The method of claim 1, wherein the pressure of the argon gas in the reactor chamber is adjusted to a pressure of about 150 mTorr to about 225 mTorr, and the intraocular lens is processed in about 3 minutes to about 5 minutes. 15. The method according to 15.