JPH05127133A - Plastic molding and production of the same - Google Patents

Abstract

PURPOSE:To impart excellent hydrophilicity to the surface of the molding while maintaining various performances, such as hardness, hard characteristic and transparency, by specifying the ratio of the silicon atom number ratio to the carbon atom number in a surface layer part and the silicon atom number ratio to the carbon atom number in the inside. CONSTITUTION:The plastic molding contg. silicon is so formed that the silicon atom number ratio to the carbon atom number within 1mum of the surface layer part is <=99% of the silicon atom number ratio to the carbon atom number in the inside. Further, <=95% is preferable and <=92% is more preferable. The surface characteristics relating to wettability with water is not improved if the ratio exceeds >99%. A method for executing a plasma treatment by using at least one kind of the gases selected from helium, neon, argon, and fluorocarbon is used as the method of specifying the silicon atom number ratio to the carbon atom number of the surface layer part to <=99% of the same ratio in the inside. Above all, the low-temp. plasma treatment method is preferred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic molded article containing a silicon atom and a method for producing a plastic molded article, which is suitable as a plastic molded article excellent in water wettability, for example, for contact lenses, intraocular lenses and the like. Used for.

[0002]

2. Description of the Related Art Recently, various plastic molded articles containing silicon have been developed. However, a plastic molded article containing silicon has insufficient water wettability, and improvement in water wettability has been desired. Therefore, for example, US Pat. No. 4,214,014 discloses in US Pat. No. 4,214,014 as an example of means for imparting water wettability to the surface of a contact lens, which is one of plastic molded articles containing silicon. A method of imparting hydrophilicity to a contact lens by performing plasma treatment is disclosed. However, when such a method is adopted, there is a problem that the material of the contact lens is deteriorated by oxygen gas.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to solve the above drawbacks, and provides a plastic molded article having improved surface water wettability while maintaining the original physical properties of the plastic, and a method for producing the same. Is provided.

[0004]

[Means for Solving the Problems] The present invention has the following constitution in order to achieve the above object.

[(1) In a plastic molded article containing silicon, the ratio of the number of silicon atoms to the number of carbon atoms within 1 mμ of the surface layer portion is 99% or less of the ratio of the number of silicon atoms to the number of carbon atoms inside. Molded plastic products.

(2) A method for producing a plastic molded article, characterized in that at least a part of silicon atoms is removed by subjecting a silicon-containing plastic molded article to plasma treatment in an atmosphere of an inert gas. The term “silicon-containing plastic molded article” in the present invention means that the polymer main chain and / or side chain contains silicon, for example, a siloxane bond or an organosilane group such as a trimethylolsilyl group. It is a molded product containing a polymer as a main component. Specific examples of such a polymer include tris (trimethylsiloxy) silylpropyl methacrylate, polydimethylsiloxane having a double bond at both ends, a homopolymer using a silicone-containing (meth) acrylate, or a homopolymer of these monomers and other monomers. And copolymers and the like. Copolymerizable monomers include monofunctional monomers such as (meth) acrylic monomers, aromatic vinyl monomers, and heterocyclic vinyl monomers, or di-, tri-, tetra- (meth) acrylic monomers, aromatic divinyl monomers, aromatic diallyl monomers. Such as polyfunctional monomers. Examples of the (meth) acrylic monomer include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate, (meth) acrylic acid, hydroxyethyl (meth) acrylate and hydroxybutyl. Hydroxyalkyl (meth) acrylates such as (meth) acrylate, halogenated alkyl (meth) acrylates such as trifluoroethyl (meth) acrylate and tetrafluoroethyl (meth) acrylate, cycloalkyl (such as cyclohexyl (meth) acrylate ( Examples thereof include (meth) acrylates. Among them, the use of methyl methacrylic acid can impart heat resistance and strength, and the use of fluoroalkyl (meth) acrylate can provide a polymer satisfying both functions of oxygen gas permeability and strength. Is preferred. Examples of the aromatic vinyl monomer include vinylbenzene, vinylnaphthalene, vinylethylbenzene and the like. Further, examples of the heterocyclic vinyl monomer include vinyl galbazole, maleimide, maleic anhydride and the like.

Next, the copolymerizable polyfunctional monomer will be described. Examples of the di (meth) acrylic monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, bisphenol A di (meth) acrylate, ethylene oxide-added di (meth) acrylate, and urethane modified propylene glycol di thereof. Examples thereof include (meth) acrylate and phosphazene (meth) acrylate.

As the tri (meth) acrylic monomer, trimethylolpropane tri (meth) acrylate, glycerol (meth) acrylate, pentaerythritol (meth) acrylate, neopentyl glycol (meth) acrylate, sorbitol (meth) acrylate, phospha Examples thereof include zentri (meth) acrylate. Examples of the tetra (meth) acrylic monomer include tetra (meth) acrylate and sorbitol tetra (meth) acrylate. Examples of aromatic divinyl compounds include o-, m-, and p-divinylbenzene, and examples of aromatic diallyl compounds include:
Examples thereof include o-, m-, and p-diallyl phthalate. Examples of other polyfunctional monomers include bismaleimide and allyl (meth) acrylate. From the viewpoint of copolymerizability, transparency, etc., di-, tri-,
Tetra-, (meth) acrylate monomers are preferred. Of these, tri (meth) acrylate is most preferable from the viewpoint of strength.

The molded article may be transparent or opaque, but since the above-mentioned polymer containing silicon used in the present invention has excellent oxygen gas permeability, it can be applied to optical materials and the like. Something is preferable, and one having transparency is preferable. The presence of silicon atoms may be uniform throughout the polymer or may be a heterogeneous system having a so-called micro phase separation structure. In particular, a heterogeneous system is particularly preferable because it provides a good balance between polymer strength and oxygen gas permeability. The diameter of the heterogeneous island component is preferably 100 mμ or more and 1000 mμ or less from the viewpoint of transparency. If it is less than 100 mμ, the balance between oxygen gas permeability and strength tends to be poor, and 1000 mμ
If it exceeds, the molded product tends to be turbid and the transparency tends to decrease. The shape of the island component can take various shapes such as spherical shape, elliptical shape, needle shape, and angular shape. Here, the diameter means the longest diameter, and the measurement method is to observe with a transmission electron microscope. Is possible.

In the present invention, it is necessary that the ratio of the number of silicon atoms to the number of carbon atoms within the surface layer portion of 1 mμ is 99% or less of the ratio of the number of silicon atoms to the number of carbon atoms inside. Further, it is preferably 95% or less, and more preferably 92% or less. If it exceeds 99%, the surface characteristics of wettability are not improved.

The number of silicon atoms referred to in the present invention is measured by X-ray photoelectron spectroscopy.

In the present invention, as a method of setting the ratio of the number of silicon atoms to the number of carbon atoms in the surface layer portion to 99% or less of the internal ratio, at least one gas selected from helium, neon, argon and freon is used. A method of plasma treatment using is used. Among them, the low temperature plasma treatment method is preferable.

Further, in order to maximize the effect, the first plasma treatment is performed in an atmosphere of at least one gas selected from the group consisting of helium, neon, argon and freon, and then the second treatment. It is preferable to perform plasma treatment using another gas selected from the above-mentioned gases. Of these, freon means CF ₄ gas, which is particularly preferable because it does not deteriorate the material of the lens even if the surface of the plastic molded product is treated for a long time. The pressure of the gas atmosphere is usually preferably in the range of 0.01 to 5.0 torr. There is no problem even if a small amount of oxygen, nitrogen, or another fluorocarbon compound is contained in the plasma treatment atmosphere.

As a device for performing the plasma treatment, it is preferable to use a vacuum chamber provided with an oscillator of high frequency, low frequency or the like. Among them, the treatment with high frequency has a remarkable effect, and generally, 13.56 MHz is used. The output is appropriately selected depending on the size of the apparatus and the product to be processed, but is usually 10 to 500 W. The treatment time is the same, but usually, a sufficient effect can be obtained by about 10 to 20 minutes. The present invention is not limited by these conditions.

As the method for producing a plastic molded article of the present invention, the most preferable low-temperature plasma apparatus will be described in more detail. For example, a decompression container having an inlet and an exhaust means for exhausting to a predetermined depressurized state is used, It is carried out by disposing a plastic molded product on both negative electrodes and maintaining a predetermined depressurized state, then discharging the Freon gas on both positive and negative electrodes to create a plasma state, and subjecting the molded product to plasma treatment.

In the present invention, as a method for producing a plastic molded product before plasma treatment, cast polymerization,
It can be used without particular limitation, such as injection molding and extrusion molding. Cast polymerization is preferably used especially when the plastic has three-dimensional cross-linking. In order to obtain a predetermined shape, it is possible to form a desired shape simultaneously with molding using an appropriate mold, but when it is necessary to create various shapes such as contact lenses, etc. It is also a useful method to use a cutting or polishing method after first forming a flat plate-shaped molded product. According to the present invention, the obtained molded article has a smaller number of silicon atoms on the surface as compared with the inside thereof, and therefore the water wettability of the surface is remarkably improved. That is, it has a hydrophilic surface, and
It is preferably applied to contact lenses, intraocular lenses, etc., because it does not impair oxygen gas permeability due to internal silicon atoms.

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to such examples.

Example 1 Polydimethylsiloxane 45 having double bonds at both ends
Parts by weight, 47.5 parts by weight of trifluoroethyl methacrylate, 3 parts by weight of methacrylic acid, and 4.5 parts by weight of trimethylolpropane trimethacrylate are uniformly mixed, and 0.05 parts by weight of azobisisobutyronitrile, azo After adding 0.15 parts by weight of biscyclohexanecarbonitrile, seal it in a test tube and heat it from 60 ° C to 110 ° C.
The temperature was raised over 4 hours, and then the temperature was maintained at 110 ° C. for 4 hours to obtain a polymer. From this, a disk shape having a thickness of about 5 mm was cut out and both sides were polished. This disk is used for high frequency oscillation frequency 13.5
Plasma treatment was performed using Freon under the conditions of 6 MHz, high frequency output 50 w, and gas atmosphere of 1.0 torr.

The silicon atom / carbon atom ratio in the surface layer portion of the resulting sample was 0.195. While inside)
The silicon atom / carbon atom ratio is 0.214, and the silicon atom / carbon atom ratio on the surface is 91.1 which is the same as the internal ratio.
%Met. The contact angle of this plasma-treated sample is 8 °
On the other hand, the contact angle of the untreated sample was 31 ° and the water wettability was extremely good. For hardness,
There was no difference between treated and untreated.

Example 2 50 parts by weight of tris (trimethylsiloxy) silylpropyl methacrylate, 50 parts by weight of trifluoroethyl methacrylate, 0.05 part by weight of azobisisobutyronitrile, and 0.15 part by weight of azobiscyclohexanecarbonitrile were added. After dissolution, the mixture was sealed in a test tube and polymerized in the same manner as in Example 1 to obtain a polymer. Two pieces having a thickness of about 5 mm were cut out from this polymer, and one of them was used for plasma treatment with Freon gas in the same manner as in Example 1. Furthermore, except that the processing gas was changed to argon gas,
The treatment was performed in the same manner, and the contact angles before and after the treatment were examined. As a result, the contact angle before the treatment was 58 ° and the contact angle after the treatment was 34 °.
And the water wettability after the treatment was extremely good. Further, the remaining one was subjected to plasma treatment with argon gas in the same manner as in Example 1 and further with freon gas in the same manner, and the change in contact angle before and after the treatment was examined. As a result, the contact angle before treatment was 58 ° and the contact angle after treatment was 36 °
The water wettability before and after the treatment was extremely good.

From the results of Examples 1 and 2, the silicon-containing plastic molded articles obtained by the present invention can be produced without lowering the hardness and hardness of the plastic molded articles.
It can be seen that hydrophilicity can be imparted to the surface.

[0022]

Industrial Applicability According to the present invention, it is possible to obtain a plastic molded article having excellent hydrophilicity on its surface while maintaining various performances such as hardness, hardness and transparency. Especially,
It is possible to impart sufficient water wettability to the surface of the contact lens, which has excellent gas permeability.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G02B 1/04 7132-2K

Claims (7)

[Claims] 1. A plastic molded article containing silicon, characterized in that the ratio of the number of silicon atoms to the number of carbon atoms within the surface layer portion of 1 mμ is 99% or less of the ratio of the number of silicon atoms to the number of carbon atoms inside. Molding. 2. The plastic molded article according to claim 1, wherein the ratio of the number of silicon atoms to the number of carbon atoms within the surface layer portion of 1 mμ is 95% or less of the ratio of the number of silicon atoms to the number of carbon atoms inside. 3. The plastic molded article according to claim 1, wherein the ratio of the number of silicon atoms to the number of carbon atoms within 1 mμ of the surface layer portion is 92% or less of the ratio of the number of silicon atoms to the number of carbon atoms inside. 4. The plastic molded product according to claim 1, wherein silicon is contained in the plastic molded product through a siloxane bond. 5. A plastic molded article containing silicon,
A plastic molded article according to claim 1, which is a gas-permeable hard contact lens. 6. A method for removing at least a part of silicon atoms by subjecting a plastic molded article containing silicon to plasma treatment under an atmosphere of at least one gas selected from helium, neon, argon and freon. A method for producing a characteristic plastic molded product. 7. The method for producing a plastic molded article according to claim 6, wherein the plastic molded article is a gas permeable hard contact lens.