JPH0219166A - Oxygen permeable molding - Google Patents

Abstract

PURPOSE:To form a lens which is transparent and has high oxygen permeability by using a block copolymer consisting of respective segments having volume fractions and the coeffts. of oxygen permeability in prescribed relations. CONSTITUTION:The oxygen permeable molding consists of the block copolymer expressed by the general formula A-B, A-B-A or B-A-B and the volumetric ratio of the segment B is 30-70%. The segment A and the segment B from a microdomain smaller than the wavelength of visible light. The coefft. of the oxygen permeability of the molding is set at 0.5-1 times (vaPa+vbPb) when the volumetric fractions of the segments A, B are respectively designated as va, vb and the coeffts. of oxygen permeability as Pa, Pb.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a molded article that has excellent transparency and higher oxygen permeability than random copolymers of the same composition.

(Prior art) In recent years, contact lenses have become widely popular as a means of vision correction, and in order to prevent oxygen deficiency disorders in the cornea, transparent materials with excellent oxygen permeability are required. Random copolymers mainly composed of siloxanyl methacrylate and methyl methacrylate are used as such materials.

(Problems to be Solved by the Invention) In order to increase the oxygen permeability of the random copolymer of siloxanyl methacrylate and methyl methacrylate, it is necessary to increase the content of siloxanyl methacrylate, which will result in a decrease in surface hardness. It has the disadvantage that it is small in size and has low tear strength.Conversely, if you try to eliminate this disadvantage, the content of siloxanyl methacrylate will be low and oxygen l;! There was a problem in that the transient properties were not sufficient and it was difficult to balance both properties at high temperatures.

The purpose of the present invention is to provide an oxygen-permeable molded product that has high oxygen permeability that can be used as an oxygen-enriching film, and that can be made into a contact lens that is transparent and has high oxygen permeability. It is about providing.

(Means for Solving the Problems) That is, the gist of the present invention consists of a block copolymer represented by the general formula A-B, A-B-A, or B-A-B, and the volume fraction of segment B is is 30 to 70%, in which segments A and B form microdomains smaller than the wavelength of visible light, and
Let v be the volume fraction and oxygen permeability coefficient of the components of segment A, respectively.
A + P a , when the volume fraction of the component of segment B and the oxygen permeability coefficient are respectively va + P R, the oxygen permeability coefficient of the molded body is (VA P a + ve P n
) is 0.5 to 1 times the oxygen permeability of the molded product.

(However, in the general formula A-B, A-B-A, or B-A-B, segment A is an alkyl methacrylate whose alkyl group has 1 to 4 carbon atoms, and 80% of its constituent monomer units are
Segment B is composed of monomer units represented by the following general formula (1) that constitute 80% by weight or more of the constituent monomer units.

CH2”C(CH3)COOC,H2111S tX
3. . . (1) (In the above general formula (1), m is an integer of 2 to 5, X is each independently a methyl group or CH3, where n is an integer of 0 to 30.)) This invention Segment A in the block copolymer used for this is an alkyl methacrylate whose alkyl group has 1 to 4 carbon atoms in an amount of 80% by weight or more, preferably 90% by weight of the constituent monomer units.
Among the alkyl methacrylates in which the alkyl group has 1 to 4 carbon atoms, methyl methacrylate is preferred.

The 100-mer structural unit copolymerizable with the alkyl methacrylate to constitute segment A includes 2,2
．． Examples include 2-1-lichloroethyl methacrylate, glycidyl methacrylate, allyl methacrylate, and ethylene dimethacrylate. The number average molecular weight of segment A is preferably about 5,000 to 100,000. If the number average molecular weight is smaller than the above lower limit, the strength of the molded product will not be sufficient, and if it is larger than the above upper limit, the transparency of the molded product will deteriorate. It is on a declining trend.

Segment B is represented by the above general formula (1) (where m.

80 parts by weight or more of the constituent monomer units are silicon-based methacrylates represented by X (X indicates the above-mentioned meaning), and a preferred specific example of this silicon-based methacrylate is tris(trimethylsiloxy)silylpropyl methacrylate. , methylbis(trimethylsiloxy)silylpropyl methacrylate, trimethylsilylpropyl methacrylate and CH3CH.

CH2-CCOOCs Ha-3i O-S i
(CH3)3H3 can be mentioned.

Monomer constituent units copolymerizable with the silicone-based methafrylate to constitute segment B include dimethylaminoethyl methacrylate, 2-trimethylsiloxyethyl methacrylate, allyl methacrylate, I
Examples include H, IH, 2H, 2H-hebutadecafluorodecyl methacrylate. The number average molecular weight of segment B is preferably about 5,000 to 100,000; if the number average molecular weight is smaller than the above lower limit, sufficient oxygen permeability cannot be obtained, and if it is larger than the above upper limit, transparency may decrease and tearing may occur. This is not preferable because it causes a decrease in strength.

The number average molecular weight of the block copolymer as a whole is:
If the block copolymer is A-B type, 10,000 to 20
For those represented by A-B-A or B-A-B, it is preferably about 1 sooo to 300,000.

The volume fraction of component B in the block copolymer is 30 to 70%
It must be. If the volume fraction of component B exceeds 70%, the surface hardness and tear strength will decrease, while if it is less than 30%, oxygen permeability will become insufficient, which is not preferred.

The above-mentioned block copolymer used in the present invention can be produced using various conventionally known ionic polymerization methods.
It is preferable to use a group transfer polymerization method such as that disclosed in Japanese Patent No. 603 because the degree of polymerization and composition of each segment can be controlled relatively easily.

In the molded article of the present invention, segment A and segment B of the block copolymer must form microdomains smaller than the wavelength of visible light;
The molded body can be made transparent. The oxygen permeability of the block copolymer molded article varies depending on the arrangement of the microdomains. In other words, when the domain of one segment is connected to the direction in which the microdomains want oxygen to permeate, it becomes a so-called parallel model, and the oxygen permeability P of the molded product is equal to the volume fraction of the component of segment A. The oxygen permeability coefficient is V Ar P a , and the volume fraction and oxygen permeability coefficient of segment B are vB and Pa, respectively.
When, P= (vAP, +VRP, l), and when each segment is stacked, it becomes a so-called series model, and it is shown as p= (VA/pH+vB/pB)-'.

It is difficult to establish an accurate model when the microdomains are random or in the case of random copolymerization, but as shown above, the volume fraction of segment B is 30 to 70%.
, the oxygen permeability in the parallel model is 0.2~
It becomes only about 0.4 times. Therefore, as mentioned above, it is difficult to balance oxygen permeability and mechanical strength with random copolymers, but the molded article of the present invention has an oxygen permeability of (VA P, +vB PB ) 0 of
．． It has a high oxygen permeability of 5 to 1 times,
As is clear from the above discussion, if the molded article has a structure in which the B segments are connected from one surface to the other, a molded article that satisfies the above conditions can be obtained. If the molding can be made into a completely parallel model, the oxygen permeability of the molded product will be (VAPa + VRPa), but some disturbance can be tolerated. If present, a good balance between oxygen permeability and mechanical strength can be achieved. In the above formula, P and Pll can be determined by preparing respective homopolymers and measuring their oxygen permeability coefficients.

A molded article with such a structure can be produced by, for example, casting a solution of a block copolymer dissolved in a solvent with a solubility parameter of 7.3 to 9.2 cal""・cm'"3", and then removing the solvent. Can be molded by

The solvent used here has a solubility parameter of 7.3 to 9.
2cal””・cm-”2, 8.4～
9.0 cal"28 cm/2 is preferable. This solubility parameter is a value calculated from a physical quantity such as heat of vaporization or a chemical structure. Examples of such solvents include the following solvents (in parentheses). The values within are the solubility parameter values).

Toluene (8,9), carbon tetrachloride (8,6), methyl isobutyl ketone (8,4), diethyl ketone (8,8)
etc.

When molded from a solution using such a solvent, the B segment of the block copolymer is microphase separated from the A segment, and a structure is created in which the B segments are connected from one surface to the other of the molded product. In addition, the size of the microdomains corresponding to each segment of the microphase-separated structure is smaller than the wavelength of visible light, making it possible to create a transparent molded product without scattering light. This is to make it possible.

If the solubility parameter of the solvent is less than 7.3 cal "2 cm-", the solution of the block copolymer will not be a homogeneous solution, and if the solubility parameter is greater than 9.2 cal "20 cm-"2 This is disadvantageous because the oxygen permeability of the obtained molded product becomes low.Also, the solubility parameter is 7.3 to 9.2c.
Even if the solvent is a l"'-am-"", it may be poorly soluble or insoluble depending on the molecular species and composition of the block copolymer, so select the solvent and casting conditions appropriately to obtain a uniform solution. Alternatively, it is better to choose a system that forms a colloidal solution.

The appropriate concentration of the block copolymer solution varies depending on the shape of the intended molded product, but is preferably about 10 to 7i.

In the present invention, first, a solution of the block copolymer is prepared, the solution is applied or poured into an appropriate frame to match the shape of the intended molded product, and then the solvent is removed by evaporation or the like. When the solvent is removed by evaporation, the desired molded product is obtained by evaporation at a temperature below the boiling point of the solvent.
Preferably, the solvent is evaporated at an evaporation rate of 0 mλ/hr or less. After the shape of the molded article is formed by solvent evaporation, it is preferable to perform post-drying to remove residual solvent in the molded article. For subsequent drying, it is preferable to vacuum dry the molded product while heating it to a temperature below the softening point.

In addition, as a method for molding thicker items or adjusting the thickness, you can mold thinner items and press multiple pieces together, adhere them with a solvent or solution, or apply an additional solution on top of the molded item. Alternatively, a method can be adopted in which the solvent is removed after injection.

The thus obtained molded product has a structure in which the B segment with high oxygen permeability is continuous from one surface to the other, and the size of the A segment and the microdomain formed by each A segment is several nm - several + nm. Since the wavelength is smaller than that of visible light, it is transparent and has high oxygen permeability.

Examples of the molded product of the present invention include ladder-shaped products such as films, sheets, and lenses. In the case of a film, it is useful as an oxygen permeable membrane or a transparent packaging material with high oxygen permeability. The membrane can have various shapes such as a flat membrane, a tubular membrane, or a hollow fiber membrane.

Furthermore, if a contact lens or an intraocular lens is molded using a lens shape with an appropriate thickness, the lens will be transparent and have excellent oxygen permeability. Furthermore, if it is formed into a sheet shape, it becomes possible to manufacture an internal viewing window or a transparent container that is transparent and has excellent oxygen permeability.

(Example) The present invention will be further explained below using Examples.

Reference Example 1 Preparation of block copolymer (A-B) 500 mIL equipped with argon inlet tube, stirrer, thermocouple, and exhaust tube
After the inside of the reaction vessel was sufficiently replaced with argon, 50 mol of tetrahydrofuran, 0.5 mJ2 of trisdimethylaminosulfonium bifluoride (0.04M solution of methyl cyanide), [(2-methoxy-2
-Methyl-1-propenyl)oxycotrimethylsilane (polymerization initiator) 0.5 mft (2.5 mmol) was charged.

Next, while stirring, 50 g (0.5 mol) of methyl methacrylate was added dropwise over 10 minutes while being careful not to allow the temperature of the reaction system to exceed 50°C. Slow stirring was continued until the temperature of the reaction system dropped to 30°C. When the temperature reached 30°C, a small amount was sampled and the molecular weight was measured by GPC. The number average molecular weight of the obtained polymer was approximately 2.
0000, which was almost the same as the expected molecular weight.

Next, tris(trimethylsiloxysilylpropyl methacrylate (118.5 mmol)) was added dropwise to this reaction system over 10 minutes to react, so that methyl methacrylate became segment A and tris(trimethylsiloxy)silylpropyl methacrylate became segment B. Synthesis 1 of the A-B type block copolymer.The obtained polymer was precipitated in water to deactivate the polymer growth terminals, and then dried to obtain a white powdery polymer.This block The number average molecular weight of the copolymer is approximately 400
It was 00.

Reference Example 2 Preparation of Block Copolymer (A-B-A) Using the same reaction apparatus as used in Reference Example 1, 25 g (0.25 mol) of methyl methacrylate was used, and the A-B block copolymer was prepared in the same manner. After synthesizing the polymer, 25 g of methyl methacrylate was further added dropwise over 10 minutes to react without deactivating the polymer growth terminals, resulting in A-
A B-A type block copolymer was synthesized. The obtained polymer was precipitated in water to inactivate the polymer growth terminals, and then dried to obtain a white powdery polymer. The number average molecular weight of this block copolymer was about 39,000.

Reference Example 3 Preparation of block copolymer (B-A-B) Using the same reaction apparatus as used in Reference Example 1, tris().limethylsiloxy)disolbrobyl methacrylate-1 was used instead of methyl methacrylate. -25g (60 mmol)
, using 50 g (0.5 mol) of methyl methacrylate in place of (trimethylsiloxy)silylpropyl methacrylate, synthesized an A-B type block copolymer by the same scanning, and then adding 25 g of (trimethylsiloxy)silylpropyl methacrylate. (60 mmol)
was added dropwise over 10 minutes to react, thereby synthesizing a B-A-B type block copolymer. The obtained polymer was precipitated in water to inactivate the polymer growth terminals, and then dried to obtain a white powdery polymer. The number average molecular weight of this block copolymer was about 38,000.

Examples 1 to 5 A-B, A-B-A and B-A synthesized in the above reference example
- 1.5 g of type B block copolymer was dissolved in 30 mfl each of toluene, carbon tetrachloride and methyl isobutyl ketone, spread on a flat glass petri dish, and heated at 30°C for 12 hours.
The solvent was left to evaporate for a while, and then vacuum dried at 120° C. for 12 hours to obtain a transparent film with a thickness of about 200 μm. The gas permeability of this film was measured using a gas permeability measuring device (
GTR-10, manufactured by Yanagimoto Seisakusho (■)) and a gas chromatograph (BC-BA, manufactured by Shimadzu Corporation (■)). Oxygen permeability coefficient PO2 (cm3 (STP) of the obtained film
) cm/cm', sec, cm) 1 g) are shown in Table 1. Comparative Examples 1 to 3 Chloroporm (solubility parameter 9.3), acetone (9,9), cyclohexanol (
Films were prepared in the same manner as in Examples 1 to 4, except that 11,4) was used, and the oxygen permeability coefficient was measured. The results are shown in Table 1 together with Examples 1 to 5.

Comparative Example 4 A film was prepared in the same manner as in Example 5 except that the casting solvent and 1.n-pentane (solubility parameter 7, O) were used. First, for this reason, it was not possible to create a film without holes, making it impossible to measure the oxygen permeation rate. Moreover, the obtained film was opaque.

Table 1 Block Solubility Oxygen Transmission Light Copolymer Solvent Lameter Overspeed Transmission
M rate Example IA, -B) - Rue > 8.9 1
．． 2 xlO-686% Example 2 A-B Carbon tetrachloride 8. δ 1. I Xl0-' 87%
Example 3 A-B MIBK 8.4
B, 6xlO-986% Example 4 A-B-A
Toluene 8.9 1. OXl0-' 8
6% Example 5 B-A-B Toluene 8.9
1. I Xl0-885% Comparative Example IA-B
Chloroporum8. 'J4. OXl0-' 85
% Comparative Example 2 A-B Acetone 8.9
2.2 Xl0-' 86% Comparative Example 3 A-B-
A Cyclohex 11.4 2. OxlO-”
84% Sanol Oxygen permeation rate unit: cm3 (STP) cm/cm2. s
ec, cmHg (36°C) As is clear from Table 1, the membrane formed by the method of the present invention is transparent and has excellent oxygen permeability.

Example 6 1.0 g of block copolymerized products synthesized in Reference Examples 1 to 3
wo each carbon tetrachloride 10. mλ, developed in a cylindrical metal container with a concave mirror surface on the bottom, and heated at 50°C for 2
The solvent was evaporated by leaving it for 4 hours, and the resulting molded product was heated to 12
Vacuum drying was carried out at 0° C. for 12 hours to obtain a molded product having a thickness of about 4 mm at the center. This molded product was fixed with the polar side facing down, and the flat side was cut into a concave shape and polished to a thickness of about 10°0 μm at the center to obtain a lens-shaped molded product with a diameter of about 10 mm. . This molded product is transparent and has an oxygen permeability of 1.0.
~1.2×10 −′, indicating high oxygen permeability.

(Effects of the Invention) As described above, the molded product of the present invention is transparent and has excellent oxygen permeability, and when compared with a conventional random polymer with the same level of oxygen permeability. Since the silicon component can be recommended, the tear strength and tensile strength will naturally be higher, and even if they have the same composition, the block copolymer method used in the present invention has better tear strength and tensile strength than the random copolymer. It has superior strength compared to conventional molded products made of oxygen permeable materials.

Hand Ito Mitsuneho Tadashi (the July 1986/Great Day 1) Amend the claims as shown in the attached sheet.

2) Page 5, line 3 of the specification " H3 3) Page 6, line 14 of the specification 2-3-19 Kyobashi, Chuo-ku, Tokyo (603) Mitsubishi Rayon Co., Ltd. President and Director: Akio Kawasaki Target of correction spontaneous correction Correct.

7゜ Contents of correction (Attachment) It is.

(Correction) Claim 1) - Molding made of a block copolymer represented by the formula A-B, A-B-A, or B-A-B, in which the volume fraction of segment B is 30 to 70%. segment A and segment B form a microdomain smaller than the wavelength of visible light, and the volume fraction of the component of segment A and the oxygen permeability coefficient are respectively MA and 7%, and the volume of the component of segment B is When the fraction and oxygen permeability coefficient are VB and PB, respectively, the oxygen permeability coefficient of the molded body is 0 of (VA Pa + vaPB).
．． Oxygen permeable molded product that is 5 times to 1 times permeable.

(However, in formula A-B, A-B-A, or B-A-B, segment A is an alkyl methacrylate whose alkyl group has 1 to 4 carbon atoms, and 80% of its constituent monomer units are
Segment B consists of 80% by weight or more of its constituent monomer units CH2, in which the 1,000 mer unit represented by formula (1) below constitutes 80% by weight or more of its constituent monomer units.
=C(CH3)COOC,H2-3i Xs・・・
(1) (In the above formula (1), m is an integer of 2 to 5, each X independently represents a methyl group, or n represents an integer of 0 to 30.

Claims (1)

[Scope of Claims] 1) A molded article consisting of a block copolymer represented by the general formula A-B, A-B-A, or B-A-B, in which the volume fraction of segment B is 30 to 70%. Segment A and segment B form a visible light wavelength ■■■■■■ black domain, and the volume fraction and oxygen permeability coefficient of the component of segment A are v_A, P_a, and segment B, respectively. When the volume fraction of the component and the oxygen permeability coefficient are v_B and P_B, respectively, the oxygen permeability coefficient of the molded body is (v_AP_a+v_B
An oxygen permeable molded article having an oxygen permeability of 0.5 to 1 times that of P_B). (However, in the general formula A-B, A-B-A, or B-A-B, segment A is an alkyl methacrylate whose alkyl group has 1 to 4 carbon atoms, and 80% of its constituent monomer units are
Segment B is composed of monomer units represented by the following general formula (1) that constitute 80% by weight or more of the constituent monomer units. CH_2=C(CH_3)COOC_mH_2_mSi
X_3...(1) (In the general formula (1) above, m is an integer from 2 to 5, and each X independently represents a methyl group or ▲a numerical formula, chemical formula, table, etc.▼. Here, n is Indicates an integer from 0 to 30.))