A method and apparatus for converting input image data in line-scan format into block-scan format, and for converting input image data in block-scan format into line-scan format. The apparatus can be implemented as a single integrated circuit which includes a memory and control logic for implementing format conversion, but no external address lines. The apparatus includes an address generator which automatically generates an address sequence for each strip of input data. Each input data strip comprises N lines of image data words, with L vectors in each line, where each vector comprises M image data words. The apparatus converts a line-scan format input data strip into blocks each consisting of N vectors. Each input data strip is processed efficiently, by automatically generating a sequence of addresses for the vectors of the strip. During each iteration of a format conversion operation, one address is generated, one vector is read out of a memory location identified by that address, and one input vector is written into the memory location. The address generator preferably generates addresses for B input data strips which comprise an image by performing a sequence of iterations during each of B cycles, where each iteration includes the step of "modulo k" addition by an increment F, where F has a different value during each cycle. The increment F for each of the cycles following the first cycle is stored as it becomes available during performance of a previous one of the cycles.

Most image sensors and displays generate or accept image data in color raster scan format. FIG. 1 represents an image being displayed in such a format, in which (horizontal) line 1 is displayed first (the pixels comprising line 1 are displayed sequentially, from left to right), and line 2 is then displayed (the pixels comprising line are 2 displayed sequentially, from left to right), and so on. For a color image, each pixel is typically driven by a set of three analog color component signals. Typically, each analog color component signal is generated by processing a multi-bit digital data word (color component sample) in a digital-to-analog conversion circuit.
In the case that a set of data in color raster scan format represents a monochrome image, the data are said to be in "line-scan" format. In the case that a set of data in color raster scan format represents a color image, the individual color component samples are interleaved.
Conventional color video data in color raster scan format can be interleaved in various different ways. For example, the data can be "pixel interleaved" so that the color component samples within each line are interleaved, or the data can be "line interleaved" so that the color component samples are interleaved on a line-by-line basis. In a frame of line interleaved color raster scan format data, each line of "red" color component samples (each "red" color component sample consisting of a multi-bit word) is followed by a line of "green" color component samples (each "green" color component sample consisting of a multi-bit word), and each line of "green" color component samples is followed by a line of "blue" color component samples (each "blue" color component sample consisting of a multi-bit word).
Throughout this specification, including in the claims, "block" denotes a set of N.times.M samples of a given color component, "word" denotes a color component sample (for example, an eight-bit word defining a red, green, or blue color component sample), "vector" denotes a succession of M words of a single color component that are contiguous on the same line, and "line length" denotes the number of words per line of image data (for the color component having the highest horizontal resolution, in the case of color image data in which the different color components have different resolution). Thus, a block of image data consists of N vectors.
Most image compression algorithms do not process image data in line-scan format, and instead process image data in N.times.M block format. For example, the conventional image compression algorithms known as the ISO "JPEG" algorithm for still images, the CCITT "H.261" recommendation for video conference, and the ISO "MPEG" algorithm for video compression, all process image data in 8.times.8 block format. Each set of block format data processed by such an algorithm is typically a sequence of "minimum coded units" or "MCUs". Each MCU (which can be thought of as a "super block" of a color image) consists of a certain number of blocks for each color component. Since different color components are sometimes sampled with different resolution, the number of blocks per color component in an MCU can vary with the color component (although the blocks for each color component in an MCU all correspond to the same area of the image).
In the case that a sequence of MCUs (i.e., a set of image data in MCU-scan format) represents a monochrome image, the data are said to be in "block-scan" format, and an MCU comprises only one block of data. In the case that data in MCU-scan format represent a color image, blocks of color component samples are interleaved within each MCU.
To implement conventional JPEG, H.261, or MPEG compression, the input data are ideally provided to the image compression processor in minimum coded unit-scan (MCU-scan) format, with each MCU consisting of data in 8.times.8 block format (M=N=8). Examples of such MCU-scan format input data include: a repeating sequence of an 8.times.8 block of red words, followed by an 8.times.8 block of green words, followed by an 8.times.8 block of blue words (image processors for processing "RGB(1:1:1)" images will expect the input data to have this format); and a repeating sequence of two 8.times.8 blocks of Y words, followed by an 8.times.8 block of U words, followed by an 8.times.8 block of V words (image processors for processing "YUV(2:1:1)" images will expect the input data to have this format).
FIG. 2 represents a sequence of blocks of one color component of the image data of FIG. 1, in the order in which such blocks can be asserted to a JPEG image compression processor. Initially, the first eight words from the first line of FIG. 1 are asserted sequentially (from left to right in FIG. 2) as vector 1 of FIG. 2. Then, the first eight words from the second line of FIG. 1 (vector 2 of FIG. 2) are asserted sequentially. Then, the first eight words from the next six lines of FIG. 1 are asserted sequentially (as vectors 3 through 8 of FIG. 2). Next, the second group of eight words from the first line of FIG. 1 are asserted sequentially (as vector 9 of FIG. 2). Thereafter, the second group of eight words from the second line of FIG. 1 are asserted sequentially (as vector 10 of FIG. 2), the second group of eight words from each of the third through eighth lines of FIG. 1 are then asserted sequentially, and so on.
A block diagram of a conventional image compression/decompression system is shown in FIG. 3. The system shown in FIG. 3 receives image data (such as video data from a camera) in color raster scan format, converts the data to MCU-scan format in format converter 20, and performs image compression on the resulting MCU-scan format data in image coding processor 22. The compressed image data asserted at the output of processor 22 are stored or transmitted, and then undergo decompression (inverse-compression) in image decoding processor 24. After undergoing decompression in processor 24, the decompressed data are converted from MCU-scan format to color raster scan format in format converter 26, and the resulting data are displayed (in color raster scan format).
Two types of conventional apparatus for converting image data between color raster scan and MCU-scan formats will next be described with reference to FIGS. 4 and 5. In the apparatus of FIG. 4, memory 32 stores image data whose format is to be converted, and image processor 30 (which performs image compression and/or decompression) supplies address signals for reading data out from, and writing data into, memory 32. In the apparatus of FIG. 5, memory 32 stores image data whose format is to be converted, and micro-controller 34 supplies address signals for writing data into memory 32 and reading format-converted data from memory 32 for subsequent processing by an image processor (not shown in FIG. 5).
In conventional systems of the type shown in FIG. 4 and 5, memory 32 includes two banks of memory. A first strip of data (i.e., N lines of color raster scan data) is read from (or written into) one bank while a second strip of data is written into (or read from) the second bank. For example (during color raster scan to MCU-scan format conversion), the first N lines of color raster scan data can be stored in the first bank of memory 32. Then, while a second set of N lines of color raster scan format data is stored in the second bank, the first strip of data is read from the first bank in MCU-scan format. Then, while a third set of N lines of color raster scan data is stored in the first bank, the second strip of data is read from the second bank in MCU-scan format, and so on.
Major disadvantages of such conventional systems for converting image data between color raster scan and MCU-scan formats include the following: a large capacity memory must be employed (i.e., a memory having capacity to store twice the number of words which comprise each strip of input data, for example, a memory for storing 2N lines of image data where each input data strip comprises N lines); and if such a large capacity memory is implemented as a single memory having two memory banks, the memory must be sufficiently fast to allow both a read access and a write access per word (i.e., the memory access speed must be at least twice the pixel rate, which limits the pixel rate in many applications).
It has been proposed to convert image data from color raster scan format into MCU-scan format in such a manner that only one address is generated per word of the input data. The address is employed to read a previously stored word from a memory location and write a new word into the same memory location.
A similar scheme is proposed in European Patent Application No. 410,909A (published Jan. 30, 1991). EPA 410,909 discloses an apparatus for converting strips of monochrome image data (such as video data) from line-scan format into column-scan format (for example, to convert three input data lines of seven words each, as shown in FIG. 2 of EPA 410,909, into seven three-word columns as shown in FIG. 3 of EPA 410,909).
Although the address generator shown in FIG. 6 of EPA 410,909 is capable of generating a sequence of addresses for reordering a strip of input data in line-scan format into column-scan format, it does so in an inefficient manner. In particular, EPA 410,909 employs a much more complicated apparatus for scan-format conversion than does the present invention, in that EPA 410,909 employs a selection circuit SEL2, an addition circuit S3, and a multiplication circuit which provide input signals to circuit SEL2, to generate coefficients for use in generating the address sequence. This logic circuitry could be eliminated by employing the inventive technique, in which required coefficients for address generation are stored for future use as they become available during an address sequence generation process.

Method and apparatus for converting image data


An exposure apparatus radiates an exposure light beam from an exposure light source onto a reticle via an illumination optical system including a first fly""s eye lens, a second fly""s eye lens, a lens system, a blind, and a condenser lens system, and it projects an image of a pattern on the reticle onto a wafer via a projection optical system. An illumination characteristic is measured by using an evaluation mark plate on a reticle stage and a spatial image-measuring system provided for a wafer stage. The states of the second fly""s eye lens and the lens system are adjusted by the aid of a driving unit on the basis of the measured value. A concentration filter plate, which is formed with a pattern of a predetermined transmittance distribution, is rotatably arranged in the vicinity of a conjugate plane with respect to an image plane between the second lens system and the blind. The angle of rotation of the concentration filter plate 51 is controlled so that the uneven illuminance is corrected. The illumination optical system can be adjusted correctly for a short period of time. It is possible to improve the uniformity of the exposure amount distribution.

1. Field of the Invention
The present invention relates to an exposure apparatus and an exposure method to be used in order to transfer a mask pattern onto a substrate through a projection optical system in the lithography step for producing, for example, semiconductor elements, liquid crystal display elements, plasma display elements, or thin film magnetic heads. In particular, the present invention relates to an exposure apparatus and an exposure method capable of controlling the distribution of illumination generated by an illumination system automatically or precisely.
2. Description of the Related Art
In order to respond to the improvement in the degree of integration and the degree of fineness of the semiconductor device, the exposure apparatus, which is in charge of the lithography step (representatively including the resist application step, the exposure step, and the resist development step) for producing the semiconductor device, is required to further enhance, for example, the resolving power and the transfer faithfulness. In order to enhance the resolving power and the transfer faithfulness as described above, it is necessary that the wavelength of the exposure light beam as the exposure beam is shortened, the projection optical system having a large numerical aperture is used, and the exposure amount is controlled highly accurately in order to expose, with a proper exposure amount, the photoresist applied on the wafer as the substrate. In order to extract the image formation characteristic of the projection optical system to the limit so that the exposure amount is controlled for the photoresist highly accurately, it is necessary to optimize the illumination optical system so as to enhance the illumination characteristic of the illumination optical system for illuminating the reticle as the mask with the exposure light beam as far as possible.
The adjustment to optimize the illumination optical system of the exposure apparatus has been hitherto performed in accordance with the following steps.
(a) An operator measures the illumination characteristic (for example, uneven illuminance) of an adjustment objective of the illumination optical system.
(b) The state (for example, position or angle of inclination) of a predetermined optical member is adjusted by using a driving unit corresponding to the illumination characteristic on the basis of the obtained result of the measurement. The driving amount concerning this process is set so that the illumination characteristic is improved as far as possible by correcting the optical design value on the basis of the experience of the operator.
(c) After the adjustment, the remaining amount of the illumination characteristic is measured again. If the remaining amount exceeds an allowable range, the adjustment is performed again by the aid of the driving unit.
(d) After the completion of the adjustment, the final state (optimum state) of the optical member is stored.
The adjustment steps as described above are repeated for every illumination characteristic of the adjustment objective for each of a plurality of illumination conditions to store the optimum state of the corresponding optical member. When the illumination condition is switched, the corresponding optical member is set to be in the optimum state respectively.
As described above, the adjustment for optimizing the illumination optical system of the conventional exposure apparatus has been performed by the operator, for example, when the exposure apparatus is assembled and adjusted and when the maintenance is performed.
However, when the operator performs the adjustment, an inconvenience arises such that a long period of time is required to perform the adjustment. Further, it is necessary to adjust the illumination optical system for each of the plurality of illumination conditions. Therefore, the overall adjustment time is fairly prolonged. The time required for the optimization is also affected by the degree of skill of the operator. Therefore, there has been also such a fear that the adjustment time is further prolonged depending on the operator.
When the states of a plurality of optical members in the illumination optical system are required to be adjusted, it is necessary to consider, for example, the mutual influence caused by the adjustment as well. Therefore, the adjustment steps have been extremely complicated.
As described above, the adjustment for the conventional illumination optical system has required the complicated steps which take a long period of time. Therefore, for example, it has been difficult to perform such an operation that the allowable level of a predetermined illumination characteristic is changed depending on, for example, the required accuracy for the device to be produced. Further, for example, the uneven illuminance of the illumination characteristic is changed in a time-dependent manner, for example, due to the cloudiness of the optical member in the illumination optical system and the deterioration of the saltpeter material in some cases. However, in such a case, it has been difficult for the conventional adjustment method to make quick response.
The uneven illuminance is principally divided into the uneven illuminance which is axially symmetrical with respect to the optical axis (centro-symmetrical unevenness), i.e., the quadratic function-like unevenness, and the inclination unevenness in which the illuminance is gradually increased or decreased in the area across the optical axis, i.e., the linear function-like unevenness. It is necessary that the uneven illuminance as described above is corrected highly accurately in the orthogonal two directions in the case of the full field exposure type exposure apparatus such as the stepper. On the other hand, in the case of the scanning exposure type exposure apparatus such as those based on the step-and-scan system, the uneven illuminance in the scanning direction is averaged by the scanning exposure operation to such an extent that little problem occurs. Therefore, it is required to especially correct the uneven illuminance in the non-scanning direction perpendicular to the scanning direction highly accurately.
The uneven illuminance has been hitherto corrected in ordinary cases by driving a group of predetermined lenses in the illumination optical system in the optical axis direction, or by driving the group of lenses so that the tilt angle about the two axes is changed. In general, the situation of the uneven illuminance differs depending on the illumination condition. Especially, in the case of the centro-symmetrical unevenness, the degree of concaveness/convexness of the illuminance is changed corresponding to the change of the position through which the light flux passes in the lens group depending on the numerical aperture of the exposure light beam (illumination light beam). Therefore, for example, as for the lens group as the adjustment objective, the optimum position is previously stored for each of the illumination conditions, and the lens group is driven to the optimum position every time when the illumination condition is changed.
A phenomenon is known, in which the cloudy substance adheres to the surface of the optical element when the exposure light beam in the ultraviolet region reacts with a minute amount of organic matter contained in the gas existing around the optical element. Usually, the gas, from which the organic matter or the like is removed, for example, through a chemical filter, is supplied to the surroundings of the respective lenses of the illumination optical system and the projection optical system. However, when the exposure apparatus is used for a long period of time, then a slight amount of remaining organic matter gradually increases the cloudiness of the lens, and the centro-symmetrical unevenness, in which the illuminance is lowered especially at the central portion, is sometimes advanced in a time-dependent manner. In such a case, the operator has adjusted the position of the corresponding lens group again, depending on the degree of advance of the centro-symmetrical unevenness. Further, for example, when the centro-symmetrical unevenness is extremely advanced during the process of the use of the exposure apparatus for several years, the lens group as the adjustment objective itself is exchanged with a lens group having a strong effect of correction in some cases.
As described above, the uneven illuminance of the conventional exposure apparatus has been corrected by controlling the tilt angle or the position of the predetermined lens group including the lens having a certain curvature (refractive power) in the optical system, or by exchanging the lens group with another lens group.
However, when it is intended to correct the uneven illuminance by driving the lens having a certain curvature other than the flat plane, the uniformity of the coherence factor ("sgr" value) of the illumination light beam is occasionally deteriorated in the illumination area on the reticle as the mask, and in the exposure area on the wafer as the substrate to be exposed. When the uniformity of the "sgr" value is deteriorated in the exposure area as described above, an inconvenience arises such that the line width uniformity, which is the original object of the suppression of the uneven illuminance, is lowered. On the other hand, if the correction amount of the uneven illuminance is set so that the deterioration of the uniformity of the "sgr" value is suppressed, a limit appears in the line width control accuracy.
Especially, in recent years, the design rule (standard line width) of the semiconductor device becomes finer and finer year by year. In order to further improve the line width control accuracy, it is demanded to develop an exposure method which makes it possible to improve the uniformity of the exposure amount distribution without deteriorating the uniformity of the "sgr" value.
Taking the foregoing viewpoints into consideration, a first object of the present invention is to provide an exposure apparatus which makes it possible to correctly adjust an illumination optical system for a short period of time.
Further, a second object of the present invention is to provide an exposure apparatus which makes it possible to substantially automatically adjust an illumination optical system which is capable of making switch to a plurality of illumination conditions.
Further, a third object of the present invention is to provide a method for efficiently using such an exposure apparatus and a method for producing a highly accurate device based on the use of such an exposure apparatus.
A fourth object of the present invention is to provide an exposure method which makes it possible to improve the uniformity of the exposure amount distribution without substantially deteriorating the uniformity of the coherence factor of an exposure light beam.
A fifth object of the present invention is to provide an exposure apparatus which makes it possible to carry out the exposure method provided in accordance with the fourth object.
A sixth object of the present invention is to provide a method for producing a device, which makes it possible to produce the device with a high line width control accuracy by using the exposure method according to the present invention.
According to a first aspect of the present invention, there is provided an exposure apparatus for exposing a second object with an exposure light beam via a first object, the exposure apparatus comprising: an illumination system which is provided with an optical member and which illuminates the first object with the exposure light beam; an illumination condition-switching system which is arranged in the illumination system and which switches an illumination condition of the first object with the exposure light beam; and
an adjusting system which adjusts a state of the optical member in the illumination system in order to control an illumination characteristic of the illumination system depending on the switched illumination condition.
According to the present invention as described above, when the illumination condition is switched with the illumination condition-switching system, the state of the optical member (for example, position in the optical axis direction, position in the direction perpendicular to the optical axis, and tilt angle) is adjusted by the aid of the adjusting system depending on the illumination condition after the switching operation. Accordingly, the predetermined illumination characteristic of the illumination system can be substantially automatically controlled to be in a desired state for a plurality of illumination conditions respectively. The adjusting system may include a driving system which moves the optical member, and a control system which controls the driving system depending on the switched illumination condition.
In this arrangement, an example of the predetermined illumination characteristic of the evaluation object is at least one of uneven illuminance of the exposure light beam and a collapse amount of a telecentric property (telecentricity) of the exposure light beam. Both of them are extremely important characteristics to obtain a high resolution on the second object. Further, it is desirable that the illumination characteristic of the evaluation objective includes an inclination component and a concave/convex component of the uneven illuminance of the exposure light beam, and inclination components (two-dimensional vector amounts) and a magnification component of the collapse amount of the telecentric property of the exposure light. The five components of the illumination characteristic can be easily controlled substantially singly by mutually independently driving a plurality of optical members in the illumination system. Therefore, it is especially easy to effect the automatization.
It is desirable that the exposure apparatus further comprises a characteristic-measuring system which measures the illumination characteristic of the illumination system, wherein the control system determines and stores a relationship between a driving amount of the driving system and an amount of change of the illumination characteristic on the basis of a result of the measurement performed by the characteristic-measuring system. When the illumination characteristic is changed in a time-dependent manner, the illumination characteristic can be quickly restored to a desired state, for example, by periodically measuring the illumination characteristic with the characteristic-measuring system, by updating the previously stored relationship by means of calculation (simulation), or by simultaneously using both of the foregoing means (i.e., by updating the relationship by means of calculation during the periodic measurement of the illumination characteristic) so that the optical member is driven on the basis of the obtained result.
According to a second aspect of the present invention, there is provided an exposure apparatus for exposing a second object with an exposure light beam via a first object, the exposure apparatus comprising:
an illumination system which is provided with an optical member and which illuminates the first object with the exposure light beam;
a characteristic-measuring system which measures an illumination characteristic of the illumination system; and
an adjusting system which adjusts a state of the optical member in accordance with a result of the measurement performed by the characteristic-measuring system.
According to the exposure apparatus as described above, the illumination system can be correctly adjusted for a short period of time by driving the adjusting system on the basis of the result of the measurement performed by the characteristic-measuring system provided with, for example, a spatial image-measuring system.
In the present invention as described above, when the illumination system includes an optical integrator (uniformizer or homogenizer) and a first optical system and a second optical system which introduce the exposure light beam passed through the optical integrator into an irradiation plane of the first object or a plane conjugate therewith, the following illumination characteristics can be controlled substantially mutually independently by performing the adjustment for the states of the foregoing optical members respectively as follows:
(a1) adjustment for the position of the optical integrator in the optical axis direction: magnification component of the collapse amount of the telecentric property of the exposure light beam;
(b1) adjustment for the position of the first optical system in the optical axis direction: concave/convex component of the uneven illuminance;
(c1) adjustment for the two-dimensional position of the second optical system in the direction perpendicular to the optical axis: inclination component of the collapse amount of the telecentric property (two-dimensional vector amount); and
(d1) adjustment for the tilt angle of the second optical system: inclination component of the uneven illuminance in the tilting direction. It is desirable that the tilting angle corresponds to the non-scanning direction perpendicular to the scanning direction in the case of the exposure apparatus based on the scanning exposure system, because of the following reason. That is, the uneven illuminance is averaged owing to the integral effect in the scanning direction, while it is desirable to make the correction with the tilt, because no averaging effect is generated in the non-scanning direction.
In the present invention described above, it is desirable that the illumination system further includes an optical element which sets an illuminance distribution of the exposure light beam to a local area for modified illumination, a beam-shaping optical system which introduces the exposure light beam from an exposure light source into the optical element, a light-collecting optical system which introduces the exposure light beam from the optical element, and the optical integrator which uniformizes the illuminance distribution of the exposure light beam from the light-collecting optical system, wherein the adjusting system adjusts the state of the light-collecting optical system or the beam-shaping optical system.
In this arrangement, for example, the beam-shaping optical system is adjusted so that the magnitude of the illuminance of the exposure light beam and magnitude of the dispersion of the illuminance distribution of the exposure light beam are balanced. Thus, it is possible to decrease the uneven illuminance on condition that the loss of the exposure light beam is minimized.
According to a third aspect of the present invention, there is provided an exposure apparatus for exposing a second object with an exposure light beam via a first object, the exposure apparatus comprising:
an illumination system which illuminates the first object with the exposure light beam;
a characteristic-measuring system which measures an illumination characteristic of the illumination system; and
a control system which independently determines a magnification component and an inclination component of a collapse amount of a telecentric property of the exposure light beam from the illumination characteristic measured by the characteristic-measuring system. It is easy to perform the adjustment substantially mutually independently by dividing the collapse amount of the telecentric property into the inclination component and the magnification component as described above. The control system may independently determine a concave/convex component and an inclination component of uneven illuminance of the exposure light beam afforded by the illumination system, from the illumination characteristic measured by the characteristic-measuring system.
According to a fourth aspect of the present invention, there is provided an exposure method for exposing a second object with an exposure light beam from an illumination system via a first object, the exposure method comprising the steps of:
illuminating the first object with the exposure light beam;
measuring an illumination characteristic of the illumination system;
independently determining a magnification component and an inclination component of a collapse amount of a telecentric property of the exposure light beam from the measured illumination characteristic;
adjusting the illumination system on the basis of the determined magnification and the inclination components of the collapse amount of the telecentric property; and
exposing the second object with the exposure light beam from the adjusted illumination system passing through the first object. According to this exposure method, the telecentric property of the illumination system can be adjusted easily for a short period of time. Thus, it is possible to improve the throughput. This method may further comprise the step of independently determining a concave/convex component and an inclination component of uneven illuminance of the exposure light beam afforded by the illumination system from the measured illumination characteristic.
According to a fifth aspect of the present invention, there is provided a method for adjusting an exposure apparatus provided with an illumination system for illuminating a first object with an exposure light beam, for exposing a second object with the exposure light beam via the first object, the method comprising the steps of:
setting a predetermined optical member in the illumination system in a plurality of states to measure an illumination characteristic of the illumination system in each state;
determining a relationship between an amount of change of the state of the optical member and an amount of change of the illumination characteristic on the basis of a result of the measurement of the illumination characteristic; and
adjusting the state of the optical member in order to control the illumination characteristic on the basis of the determined relationship. According to this adjusting method, it is possible to efficiently adjust the illumination characteristic by previously determining the relationship between the driving amount of the optical member and the amount of change of the illumination characteristic. The method may further comprise the step of storing the determined relationship.
According to a sixth aspect of the present invention, there is provided an exposure method for exposing a second object with an exposure light beam via a first object, the exposure method comprising the steps of:
radiating the exposure light beam onto the first object; and
controlling a transmittance distribution of the exposure light beam in a planer area traversing an optical axis of the exposure light beam in the vicinity of an exposure plane of the second object or in the vicinity of a plane conjugate with the exposure plane.
According to the exposure method as described above, the uneven illuminance is adjusted not by driving an optical element having a predetermined curvature other than the flat plane. The transmittance distribution of the planer area is controlled (especially controlled two-dimensionally) so that the uneven illuminance is corrected. Accordingly, the illuminance distribution can be controlled without substantially deteriorating the uniformity of the coherence factor of the exposure light beam in the exposure area of the second object. Therefore, the illuminance distribution is controlled so that the unevenness of the cumulative exposure amount on the second object is corrected, and thus it is possible to improve the uniformity of the exposure amount distribution so that the line width uniformity may be reliably improved. Further, the transmittance distribution is not fixed, it can be controlled variably two-dimensionally. Therefore, when any cloudiness or the like appears on the optical element such as those of the illumination system, and the illuminance distribution on the second object is changed in a time-dependent manner, then the transmittance distribution is controlled so that the change is offset. Thus, it is possible to always maintain high uniformity of the exposure amount distribution.
In this process, for example, the transmittance distribution for the exposure light beam is controlled to give a concentric distribution about the center of the optical axis so that the unevenness of the exposure amount distribution for the second object is corrected. When the concentric distribution is given as described above, it is possible to appropriately correct the uneven illuminance (centro-symmetrical unevenness) which is axially symmetrical with respect to the optical axis. Further, the centro-symmetrical unevenness can be corrected substantially continuously within a predetermined range by rotating the transmittance distribution.
In another example, the transmittance distribution for the exposure light beam is controlled to give a predetermined distribution in a first direction so that the unevenness of the exposure amount distribution for the second object is corrected. That is, the transmittance distribution is controlled to give a one-dimensional predetermined distribution. The direction of the one-dimensional distribution is variable. When the one-dimensional transmittance distribution is used as described above, it is possible to correct the unevenness of the cumulative exposure amount in the non-scanning direction (direction perpendicular to the scanning direction) when the scanning exposure is performed. That is, when the predetermined distribution is a distribution which changes one-dimensionally symmetrically about the center of the optical axis, the centro-symmetrical unevenness (quadratic function-like unevenness) can be corrected substantially continuously within a predetermined range after the scanning exposure. When the predetermined distribution is a distribution in which the transmittance is gradually increased or decreased as the position is separated farther from the optical axis, the inclination unevenness (linear function-like unevenness) can be corrected substantially continuously within a predetermined range after the scanning exposure.
The transmittance distribution for the exposure light beam may be further controlled in a direction intersecting the direction of the predetermined distribution with the same distribution as the predetermined distribution or with another distribution. When a plurality of one-dimensional transmittance distributions are combined, it is possible to correct the two-dimensional uneven illuminance such as the inclination unevenness and the centro-symmetrical unevenness in the stationary state. The present invention can be also applied to the exposure apparatus of the full filed exposure type such as the stepper. It is also possible to omit the mechanism for driving a large lens group to be used to correct the uneven illuminance.
In the scanning exposure system in which the first object and the second object are synchronously moved in a scanning direction when the second object is exposed, it is desirable that the transmittance distribution for the exposure light beam is controlled so that exposure amount distribution (exposure amount distribution in the non-scanning direction), which is obtained by adding up an exposure amount of the exposure light beam for the second object in the scanning direction, is uniformized. In this process, the uneven illuminance in the scanning direction is averaged by the scanning exposure. Therefore, the cumulative exposure amount distribution is uniformized on the entire surface of the second object by uniformizing the exposure amount distribution in the non-scanning direction perpendicular to the scanning direction. Thus, it is possible to obtain a high line width control accuracy.
According to a seventh aspect of the present invention, there is provided an exposure apparatus for exposing a second object with an exposure light beam via a first object, the exposure apparatus comprising:
an illumination system which illuminates the first object with the exposure light beam; and
at least one filter which is arranged in the vicinity of an exposure plane of the second object or in the vicinity of a plane conjugate with the exposure plane on an optical path for the exposure light beam up to the second object and which has a predetermined transmittance distribution with respect to the exposure light beam.
According to the present invention as described above, the transmittance distribution can be controlled substantially continuously, for example, by mechanically rotating the filter, or by electrically rotating the transmittance distribution of the filter. Therefore, it is possible to carry out the exposure method according to the sixth aspect of the present invention. In this arrangement, the apparatus may further comprise a driving unit which controls an angle of rotation of the filter itself or which makes control to electrically rotate the transmittance distribution of the filter. Accordingly, it is possible to automatically correct the unevenness of the exposure amount.
In this arrangement, the illumination system may include one stage of optical integrator or a plurality of stages of optical integrators for uniformizing an illuminance distribution of the exposure light beam, and a field diaphragm for defining an illumination area on the first object of the exposure light beam from the optical integrator; wherein the filter may be arranged on a plane in the vicinity of the field diaphragm or on a plane in the vicinity of an irradiation plane of the first object. Accordingly, the filter can be easily arranged.
The filter may be composed of two sheets of a first filter and a second filter which have the same transmittance distribution in a one-dimensional direction symmetrically with respect to an optical axis respectively, and the two sheets of the filters may be rotated in mutually opposite phases. Accordingly, the centro-symmetrical unevenness can be corrected continuously by means of the simple control. When the present invention is applied to an exposure apparatus based on the scanning exposure system, it is desirable that the exposure apparatus further comprises a stage system which synchronously moves the first object and the second object in a scanning direction; an exposure amount distribution-measuring unit which measures a distribution of added-up value in the scanning direction of an exposure amount of the exposure light beam on the second object; and a control unit which controls an angle of rotation of the filter by the aid of the driving unit in accordance with the exposure amount distribution measured by the distribution-measuring unit. In this arrangement, the unevenness of the exposure amount can be corrected highly accurately by measuring the distribution of the added-up value in the non-scanning direction with the distribution-measuring unit, and rotating the filter so that the distribution is uniform.
According to an eighth aspect of the present invention, there is provided an exposure apparatus for illuminating a first object with an exposure light beam and exposing a second object with the exposure light beam via the first object, the exposure apparatus comprising:
an illumination optical system which is capable of illuminating the first object under a plurality of illumination conditions respectively and in which an illuminance distribution of the exposure light beam has an identical tendency for the plurality of illumination conditions respectively; and
an optical member which is arranged on an optical path for the exposure light beam up to the second object and which adjusts the illuminance distribution.
According to the exposure apparatus of the present invention as described above, when the illumination condition is changed, for example, from the ordinary illumination to the modified illumination or the small "sgr" value illumination, the uniformity of the exposure amount distribution can be improved by offsetting the amount of change of the uneven illuminance by means of the optical member, for example, when the degree of the centro-symmetrical unevenness or the inclination unevenness is slightly changed.
In this arrangement, it is desirable that the illumination optical system is adjusted to have uneven illuminance in which the illuminance distribution is substantially symmetrical with respect to an optical axis of the illumination optical system. Accordingly, it is easy to correct the uneven illuminance. For example, the optical member includes at least one optical fiber which is arranged separately from an exposure plane of the second object or a conjugate plane thereof and which has a predetermined transmittance distribution with respect to the exposure light beam.
According to an ninth aspect of the invention, an exposure method for illuminating a first object with an exposure light beam and exposing a second object with the exposure light beam via the first object is provided. The exposure method comprises:
changing an illumination condition for the first object depending on a pattern to be transferred onto the second object;
adjusting an inclination component and a centro-symmetrical component of uneven illuminance or uneven exposure amount in an irradiation area of the exposure light beam, respectively; and
adjusting the centro-symmetrical component without adjusting the inclination component during a predetermined period after the adjustment of the uneven illuminance or uneven exposure amount.
According to an tenth aspect of the invention, an exposure method for irradiating a first object with an exposure light beam via an illumination optical system and exposing a second object with the exposure light beam via the first object is provided. The exposure method comprises:
detecting the exposure light beam on a predetermined plane on which the second object is arranged to measure an illumination characteristic including at least one of a distribution of exposure amount or illuminance in an irradiation area of the exposure light beam and a telecentricity of the illumination optical system;
moving at least one optical element of the illumination optical system on the basis of the measured illumination characteristic;
updating the measured illumination characteristic by means of calculation until the illumination characteristic is measured next time; and
moving the at least one optical element on the basis of the updated illumination characteristic.
A method for producing a device according to the present invention comprises the step of transferring a device pattern onto a substrate by using the exposure method according to any one of the aspects of the present invention. According to the present invention, it is possible to mass-produce a highly functional device with a high line width control accuracy.

Exposure apparatus and exposure method capable of controlling illumination distribution


A vehicle roof comprising at least one cover element, which selectively closes or at least partially exposes a roof opening and which, with respect to the vehicle longitudinal center plane, comprises a carrier element on either side, said carrier element being provided with a gate and interacting with an adjusting device, which is guided in a guide rail arranged in the vehicle longitudinal direction and comprises a carriage element, which interacts with the gate of the respective carrier element at least in order to pivot the cover element and comprises a guide section on which the carrier element rests. The guide section is formed by a wall of a plastic component, which can be elastically deformed and give way in a hollow space formed by the plastic component.

1. Field of the Invention
The invention relates to a vehicle roof with at least one cover element which optionally closes or at least partially opens up a roof opening.
2. Related Technology
A vehicle roof of this type is known, for example, from U.S. Pat. No. 6,695,398 B2 and comprises a cover element which, along both lateral edges thereof with respect to the vehicle longitudinal center plane, is provided with a carrier element which constitutes a pivoting or deployment arm. Guide rails, in each of which one of the carrier elements is displaceably guided, are arranged along the lateral edges of the roof opening. The carrier elements each interact with an adjustment device which comprises a carriage element which is provided with a claw which interacts with a guide track or control track of the particular carrier element. Movement of the carriage elements in the guide rails triggers a pivoting movement of the carrier elements and therefore of the cover element.
Furthermore, it is known from practice, in the case of carriage elements according to the type described above, to form a guide section on which the lower side of the particular carrier element rests and which consists of an elastically mounted steel roller which is formed from a rolling bearing steel tube in which a damper forming the elastic mounting is embedded. Such a guide section which is formed from a steel roller is also highly cost-intensive. Adequate compensation for tolerances in the vertical direction of the vehicle may possibly not be possible because of the small dimensions of the damper. Also, high surface pressure prevails because of the linear contact, which is predetermined by the steel roller, with the guide web formed on the particular carrier element. This may in turn lead, when the adjustment device is actuated, to undesirable noises occurring because of the "stick-slip effect".


An ocular lens material comprising a siloxane-containing polymer obtained by polymerizing a monomer mixture containing (A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and (B) a vinyl ester of lower fatty acid as essential components. An ocular lens material comprising a polymer obtained by saponification of the siloxane-containing polymer. Processes for producing the ocular lens materials. The ocular lens materials are excellent not only in lipid-stain resistance, wettability and oxygen permeability, but also in flexibility, particularly, shape recovery at the same time.

The present invention relates to an ocular lens material and a process for producing the same. More particularly, the present invention relates to an ocular lens material suitably used for, for example, soft contact lens and soft intraocular lens, which is excellent not only in lipid-stain resistance, wettability and oxygen permeability, but also in flexibility, particularly, shape recovery at the same time, and a process for producing the ocular lens material.
Recently, consumer""s demands for contact lenses, for example, are directed to a soft contact lens with high oxygen permeability, and for intraocular lenses, for example, a foldable intraocular lens. For these reasons, various materials having properties such as high oxygen permeability and excellent flexibility in particular are suggested.
For instance, a contact lens comprising a copolymer obtained by polymerizing siloxanyl (meth)acrylate and vinyl ester is disclosed in Japanese Unexamined Patent Publication No. 163811/1988, and a contact lens comprising a copolymer obtained by polymerizing siloxanyl (meth)acrylate, a vinyl ester, and vinyl (meth)acrylate and/or allyl (meth)acrylate is disclosed in Japanese Unexamined Patent Publication No. 301919/1988.
However, it cannot be said that these contact lenses are excellent in flexibility taking the monomer mixture into account though all of them have high oxygen permeability and excellent stain resistance.
In addition to the above, a water-containing contact lens obtained by saponifying a polymer comprising a (meth)acrylate polymer, which has at least one polymerizable group on average, a vinyl monomer, a vinyl ester of fatty acid and a crosslinkable monomer, is disclosed in Japanese Unexamined Patent Publication No. 102471/1994, and a silicone-containing hydrogel material formed from a polymer prepared by using a monomer mixture comprising a polysiloxane pre-polymer, a bulk polysiloxanylalkyl (meth)acrylate monomer and a hydrophilic monomer is disclosed in Japanese Unexamined Patent Publication No. 508063/1995. Also, in International Publication No. WO 97/09169, an ocular lens material obtained by hydrating, by using a water-soluble organic solvent, a polymer prepared by solution polymerization of a polymerizable silicon-containing compound and/or a polymerizable fluorine-containing compound, hydroxyalkyl (meth)acrylate, and a cross-linked compound is disclosed.
However, though these contact lenses and materials have properties such as high oxygen permeability, lipid-stain resistance and wettability, they only have one or a plurality of such properties, and do not show flexibility, particularly shape recovery, which is one of the important properties required for an ocular lens material, in particular, a soft ocular lens material.
As mentioned above, ocular lens materials having not only high oxygen permeability, excellent lipid-stain resistance and superior wettability but also shape recovery at the same time have not been provided yet. Accordingly, development of such materials as the above has been expected.
The present invention has been carried out from the viewpoint of the above prior arts. An object of the present invention is to provide an ocular lens material which has not only high oxygen permeability, excellent wettability and superior lipid-stain resistance, but also flexibility, particularly shape recovery at the same time, and an easy process for producing the ocular lens material.
The present invention relates to
(1) an ocular lens material comprising a siloxane-containing polymer obtained by polymerizing a monomer mixture containing
(A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and
(B) a vinyl ester of lower fatty acid as essential components;
(2) an ocular lens material comprising a polymer prepared by saponifying a siloxane-containing polymer obtained by polymerizing a monomer mixture containing
(A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and
(B) a vinyl ester of lower fatty acid as essential components; and
(3) a process for producing the above ocular lens material, characterized by preparing a siloxane-containing polymer by polymerization of a monomer mixture containing
(A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and
(B) a vinyl ester of lower fatty acid as essential components; and then
subjecting said siloxane-containing polymer to saponification.
The ocular lens material of the present invention, hereinafter referred to as an ocular lens material I, comprises a siloxane-containing polymer obtained by polymerizing a monomer mixture containing (A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and (B) a vinyl ester of lower fatty acid as essential components.
The siloxane macromonomer (A) is a component which mainly imparts flexibility as typified by shape recovery and mechanical strength to the ocular lens material I.
The active unsaturated group in the siloxane macromonomer (A) is an active unsaturated group which can be subjected to radical polymerization. Examples of the active unsaturated group are (meth)acryloyl group, vinyl group, allyl group, (meth)acryloyloxy group, vinyl carbamate group and the like. Among these, acryloyloxy group and vinyl group are preferable from the viewpoint that they can impart excellent flexibility to the ocular lens material I and copolymerizability with other monomers is excellent.
In the instant specification, xe2x80x9c(meth)acrylxe2x80x94xe2x80x9d means xe2x80x9cacrylxe2x80x94 and/or methacrylxe2x80x94xe2x80x9d.
It is desired that a number average molecular weight of the siloxane macromonomer (A) is at least 2,000, preferably at least 2,500 and more preferably at least 3,000 in order to impart excellent flexibility to the ocular lens material I without increasing hardness extremely. Also, it is desired that a number average molecular weight of the siloxane macromonomer (A) is at most 100,000, preferably at most 50,000, more preferably at most 10,000 not to make shape recovery inferior though the ocular lens material I becomes softened.
As the siloxane macromonomer (A), for example, the macromonomer of dialkyl siloxane having an active unsaturated group described in U.S. Pat. No. 4,189,546 specification can be used to obtain the aimed ocular lens material I.
Usually, many siloxane macromonomers are bad in wettability and relatively lack mechanical strength when each of the macromonomers is homopolymerized. Accordingly, as the siloxane macromonomer (A) used in the present invention, a siloxane macromonomer having a urethane group represented by the formula:
in the macromonomer structure is preferable in order to improve wettability.
When the siloxane macromonomer (A) contains the above urethane group, suitable mechanical strength and excellent wettability can be imparted to the ocular lens material I. It is desired that the number of the urethane group in the siloxane macromonomer (A) is at least 2, preferably at least 4 on average in order to impart sufficient mechanical strength and wettability. On the other hand, when too many urethane groups are introduced, flexibility of the ocular lens material I decreases. Therefore, it is desired that the average number of the urethane group in the siloxane macromonomer (A) is at most 20, preferably at most 14.
In the present invention, the macromonomer to which hydrophilic parts are introduced at the both ends of the siloxane structure described in U.S. Pat. No. 4,495,361 specification or U.S. Pat. No. 5,807,944 specification can also be used as the siloxane macromonomer (A) in order to obtain the ocular lens material I whose flexibility, particularly shape recovery, is improved.
In the present invention, as the siloxane macromonomer (A), a macromonomer represented by the formula (I-1) is preferably used:
A1xe2x80x94(xe2x80x94U1xe2x80x94S1xe2x80x94)nxe2x80x94U2xe2x80x94S2xe2x80x94U3xe2x80x94A2xe2x80x83xe2x80x83(I-1)
wherein each of A1 and A2 is independently an active unsaturated group, an active unsaturated group having an alkylene group having 1 to 20 carbon atoms or an active unsaturated group having an alkylene glycol group having 1 to 20 carbon atoms;
U1 is a diurethane type group which contains urethane bonds formed with adjacent A1 and adjacent S1 on both sides or which contains urethane bonds with adjacent two S1 on both sides;
U2 is a diurethane type group which contains urethane bonds formed with adjacent A1 and adjacent S2 on both sides or which contains urethane bonds with adjacent S1 and adjacent S2 on both sides;
U3 is a diurethane type group which contains urethane bonds formed with adjacent S2 and adjacent A2 on both side;
each of S1 and S2 is independently a group represented by the formula:
wherein each of R1 and R2 is independently an alkylene group having 1 to 20 carbon atoms, each of R3, R4, R5, R6, R7 and R8 is independently a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, which may be substituted with a fluorine atom, or a group represented by the formula:
A3xe2x80x94U4xe2x80x94R1xe2x80x94Oxe2x80x94R2xe2x80x94
in which A3 is an active unsaturated group, an active unsaturated group having an alkylene group having 1 to 20 carbon atoms or an active unsaturated group having an alkylene glycol group having 1 to 20 carbon atoms, U4 is a urethane type group which contains urethane bonds formed with adjacent A3 and adjacent R1 on both sides, and each of R1 and R2 is the same as above, x is an integer of 1 to 1500, y is 0 or an integer of 1 to 1499, and x+y is an integer of 1 to 1500;
n is 0 or an integer of 1 to 10;
or a macromonomer represented by the following formula (I-2) is preferably used:
xe2x80x83B1xe2x80x94S3xe2x80x94B1xe2x80x83xe2x80x83(I-2)
wherein B1 is an active unsaturated group having urethane bond; and
S3 is a group represented by the formula:
wherein each of R1 and R2 is independently an alkylene group having 1 to 20 carbon atoms, each of R3, R4, R5, R6, R7 and R8 is independently a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, which may be substituted with fluorine atom, or a group represented by the formula:
A3xe2x80x94U4xe2x80x94R1xe2x80x94Oxe2x80x94R2xe2x80x94
in which A3 is an active unsaturated group, an active unsaturated group having an alkylene group having 1 to 20 carbon atoms or an active unsaturated group having an alkylene glycol group having 1 to 20 carbon atoms, U4 is a urethane type group which contains urethane bonds formed with adjacent A3 and adjacent R1 on both sides, and each of R1 and R2 is the same as above, x is an integer of 1 to 1500, y is 0 or an integer of 1 to 1499, and x+y is an integer of 1 to 1500.
In the formula (I-1), examples of the active unsaturated group represented by A1 and A2 are (meth)acryloyl group, vinyl group, allyl group, (meth)acryloyloxy group, vinyl carbamate group and the like as mentioned above. Among them, acryloyloxy group and vinyl group are preferable and acryloyloxy group is particularly preferable, since more excellent flexibility can be imparted to the ocular lens material I and copolymerizability with other monomers is excellent.
When the above active unsaturated group has an alkylene group or an alkylene glycol group, it is desired that the number of carbon atoms of the alkylene group or the alkylene glycol group is 1 to 20, preferably 1 to 10.
In the formula (I-1), as to the group S1 or S2 represented by the formula:
wherein each of R1, R2, R3, R4, R5, R6, R7, R8, x and y is the same as above, each of R1 and R2 is preferably an alkylene group having 1 to 5 carbon atoms, and each of R3, R4, R5, R6, R7 and R8 is preferably an alkyl group having 1 to 5 carbon atoms. A3 in the formula: A3xe2x80x94U4xe2x80x94R1xe2x80x94Oxe2x80x94R2xe2x80x94, which represents R3, R4, R5, R6, R7 or R8, is the same active unsaturated group as the above-exemplified one. When the active unsaturated group has an alkylene group or an alkylene glycol group, it is desired that the number of carbon atoms of the alkylene group or the alkylene glycol group is 1 to 20, preferably 1 to 10 carbon atoms. In addition, it is desired that x is an integer of 1 to 500, y is 0 or an integer of 1 to 499, and x+y is an integer of 1 to 500.
In the formula (I-1), it is desired that n is 0 or an integer of 1 to 5.
In the formula (I-2), examples of the active unsaturated group having urethane bond, represented by B1 are (meth)acryloylisocyanate group, (meth)acryloyloxyisocyanate group, allylisocyanate group, vinylbenzylisocyanate group and the like. The group represented by S3 in the formula (I-2) is the same as the group represented by S1 or S2 in the above formula (I-1).
Among the above macromonomers, because flexibility such as shape recovery and mechanical strength can be greatly imparted to the lens material, a macromonomer represented by the formula:
A1xe2x80x94U2xe2x80x94S2xe2x80x94U3xe2x80x94A2
wherein each of A1, A2, U2, U3 and S2 is the same as above; and a macromonomer represented by the formula:
A1xe2x80x94(xe2x80x94U1xe2x80x94S1xe2x80x94)nxe2x80x2xe2x80x94U2xe2x80x94S2xe2x80x94U3xe2x80x94A2
wherein each of A1, A2, U1, U2, U3, S1 and S2 is the same as above, and nxe2x80x2 is an integer of 1 to 4, are preferable. In particular, a macromonomer represented by the formula:
wherein A is a group represented by the formula:
and a is an integer of 20 to 50, is preferable.
The above vinyl ester of lower fatty acid (B) is a component which mainly imparts shape recovery to the ocular lens material I and hydrophilic property to the ocular lens material II according to the saponification mentioned below.
Typical examples of the vinyl ester of lower fatty acid (B) is a compound represented by the formula (II):
wherein R is hydrogen atom or an alkyl group having 1 to 15 carbon atoms, which may be substituted with a halogen atom. Concrete examples of the compound are vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl monochloroacetate, vinyl monofluoroacelate, vinyl trichloroacetate, vinyl trifluoroacetate and the like. These can be used alone or in a mixture thereof.
Among the above vinyl esters of lower fatty acid (B), because shape recovery and hydrophilic property can be greatly imparted to the lens material, vinyl acetate, vinyl propionate and vinyl pivalate are preferable. In particular, vinyl acetate is preferable.
The siloxane-containing polymer which constitutes the ocular lens material I of the present invention is prepared by polymerizing the monomer mixture containing the siloxane macromonomer (A) and the vinyl ester of lower fatty acid (B) as essential components. The monomer mixture can also contain, for instance, a silicon-containing monomer (C).
The above silicon-containing monomer (C) is preferably used since it is a component which mainly imparts oxygen permeability and further, flexibility, particularly shape recovery, to the ocular lens material I.
Typical examples of the silicon-containing monomer (C) are a silicon-containing (meth)acrylate such as pentamethyldisiloxanylmethyl (meth)acrylate, trimethylsiloxydimethylsilylpropyl (meth)acrylate, methylbis(trimethylsiloxy)silylpropyl (meth)acrylate, tris(trimethylsiloxy)silylpropyl (meth)acrylate, mono[methylbis(trimethylsiloxy)siloxy]bis(trimethylsiloxy)silylpropyl (meth)acrylate, tris[methylbis(trimethylsiloxy)siloxy]silylpropyl (meth)acrylate, trimethylsilylmethyl (meth)acrylate, trimethylsilylpropyl (meth)acrylate, methylbis(trimethylsiloxy)silylethyltetramethyldisiloxanylmethyl (meth)acrylate, tetramethyltriisopropylcyclotetrasiloxanylpropyl (meth)acrylate, tetramethyltriisopropylcyclotetrasiloxybis(trimethylsiloxy)silylpropyl (meth)acrylate or trimethylsiloxydimethylsilylpropyl (meth)acrylate; a silicon-containing styrene derivative represented by the formula:
wherein p is an integer of 1 to 15, q is 0 or 1 and r is an integer of 1 to 15, such as tris(trimethylsiloxy)silylstyrene, methylbis(trimethylsiloxy)silylstyrene, dimethylsilylstyrene, trimethylsilylstyrene, tris(trimethylsiloxy)siloxanyldimethylsilylstyrene, [methylbis(trimethylsiloxy)siloxanyl]dimethylsilylstyrene, pentamethyldisiloxanylstyrene, heptamethyltrisiloxanylstyrene, nonamethyltetrasiloxanylstyrene, pentadecamethylheptasiloxanylstyrene, heneicosamethyldecasiloxanylstyrene, heptacosamethyltridecasiloxanylstyrene, hentriacontamethylpentadecasiloxanylstyrene, trimethylsiloxypentamethyldisiloxymethylsilylstyrene, tris(pentamethyldisiloxy)silylstyrene, [tris(trimethylsiloxy)siloxanyl]bis(trimethylsiloxy)silylstyrene, methylbis(heptamethyltrisiloxy)silylstyrene, tris[methylbis(trimethylsiloxy)siloxy]silylstyrene, trimethylsiloxybis[tris(trimethylsiloxy)siloxy]silylstylene, heptakis(trimethylsiloxy)trisiloxanylstyrene, tris[tris(trimethylsiloxy)siloxy]silylstyrene, [tris(trimethylsiloxy)hexamethyltetrasiloxyl][tris(trimethylsiloxy)siloxy]trimethylsiloxysilylstyrene, nonakis(trimethylsiloxy)tetrasiloxanylstyrene, methylbis(tridecamethylhexasiloxy)silylstyrene, heptamethylcyclotetrasiloxanylstyrene, heptamethylcyclotetrasiloxybis(trimethylsiloxy)silylstyrene or tripropyltetramethylcyclotetrasiloxanylstyrene; and the like. These can be used alone or in admixture thereof.
Among the above silicon-containing monomers (C), because high oxygen permeability and flexibility, in particular, shape recovery can be greatly imparted to the ocular lens material I at the same time, the silicon-containing (meth)acrylate is preferable. In particular, tris(trimethylsiloxy)silylpropyl acrylate is preferable.
Furthermore, the monomer mixture can also contain, for instance, a fluorine-containing monomer (D), in addition to the siloxane macromonomer (A), the vinyl ester of lower fatty acid (B) and the silicon-containing monomer (C).
The fluorine-containing monomer (D) is a component which mainly imparts oxygen permeability and flexibility to the ocular lens material I, improving lipid-stain resistance at the same time.
Typical examples of the fluorine-containing monomer (D) are 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,3,3-tetrafluoro-t-pentyl (meth)acrylate, 2,2,3,4,4,4-hexafluorobutyl (meth)acrylate, 2,2,3,4,4,4-hexafluoro-t-hexyl (meth)acrylate, 2,3,4,5,5,5-hexafluoro-2,4-bis(trifluoromethyl)pentyl (meth)acrylate, 2,2,3,3,4,4-hexafluorobutyl (meth)acrylate, 2,2,2,2xe2x80x2,2xe2x80x2,2xe2x80x2-hexafluoroisopropyl (meth)acrylate, 2,2,3,3,4,4,4-heptafluorobutyl (meth)acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl (meth)acrylate; a fluoroalkyl (meth)acrylate represented by the formula:
wherein R1 is a fluoroalkyl group having 3 to 15 carbon atoms and R2 is hydrogen atom or a methyl group, such as 3-perfluorobutyl-2-hydroxypropyl (meth)acrylate, 3-perfluorohexyl-2-hydroxypropyl (meth)acrylate, 3-perfluorooctyl-2-hydroxypropyl (meth)acrylate, 3-(perfluoro-3-methylbutyl)-2-hydroxypropyl (meth)acrylate, 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl (meth)acrylate or 3-(perfluoro-7-methyloctyl)-2-hydroxypropyl (meth)acrylate; and the like.
Among them, fluoroalkyl acrylate is preferable since flexibility can be greatly imparted to the ocular lens material I particularly out of oxygen permeability, flexibility and lipid-stain resistance.
Usually, many fluorine-containing compounds can impart oxygen permeability and lipid-stain resistance to a material, but are bad in wettability. To the contrary, a fluoroalkyl acrylate having a hydroxyl group represented by the formula:
wherein Rxe2x80x21 is a perfluoroallyl group having 3 to 15, preferably 3 to 8, more preferably 4 to 6 carbon atoms is particularly preferable from the viewpoint that flexibility and wettability can be imparted to the ocular lens material I without lacking oxygen permeability and lipid-stain resistance.
The proportion of the siloxane macromonomer (A), the vinyl ester of lower fatty acid (B) and the silicon-containing monomer (C) used as occasion demands is preferably defined as mentioned below. That is, in order to impart sufficient flexibility, mechanical strength and oxygen permeability to the ocular lens material I, it is desired that the ratio of the total weight of the siloxane macromonomer (A) and the silicon-containing monomer (C) to the weight of the vinyl ester of lower fatty acid (B), the total weight of (A) and (C)/the weight of (B), that is, when the silicon-containing monomer (C) is not used, the weight of (A)/the weight of (B), is at least 30/70, preferably at least 50/50. In order to impart sufficient shape recovery and hydrophilic property to the ocular lens material I, it is desired that the above ratio is at most 90/10, preferably at most 80/20.
When the silicon-containing monomer (C) is used, the ratio of the weight of the siloxane macromonomer (A) to the weight of the silicon-containing monomer (C), the weight of (A)/the weight of (C), is preferably defined as mentioned below. That is, in order to impart sufficient mechanical strength to the ocular lens material I without lowering shape recovery, it is desired that the weight of (A)/the weight of (C) is at least 20/80, preferably at least 25/75. In order to impart sufficient oxygen permeability to the ocular lens material I, it is desired that the above ratio is at most 90/10, preferably at most 80/20.
The proportion of the siloxane macromonomer (A) and the vinyl ester of lower fatty acid (B), and the silicon-containing monomer (C) and the fluorine-containing monomer (D) which are used as occasion demands is preferably defined as mentioned below. That is, in order to impart effects from the siloxane macromonomer (A), the vinyl ester of lower fatty acid (B) and the silicon-containing monomer (C) sufficiently to the ocular lens material I, it is desired that the ratio of the total weight of siloxane macromonomer (A), the vinyl ester of lower fatty acid (B) and the silicon-containing monomer (C) to the weight of the fluorine-containing monomer (D), the total weight of (A), (B) and (C)/the weight of (D), is at least 20/80, preferably at least 40/60. In order to impart sufficient lipid-stain resistance in particular to the ocular lens material I, it is desired that the above ratio is at most 90/10, preferably at most 85/15.
As occasion demands, the monomer mixture can also contain a crosslinkable compound (E) having at least two polymerizable groups.
The above crosslinkable compound (E) is a component which mainly imparts optical properties such as transparency to the ocular lens material I and further improves mechanical strength thereof so that the ocular lens material I can be used as a lens material.
Typical examples of the crosslinkable compound (E) are ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, methacryloyloxydiethyl acrylate, divinylbenzene, diallyl phthalate, diallyl adipate, diethylene glycol diallyl ether, triallylisocyanurate, xcex1-methylene-N-vinylpyrrolidone, 4-vinylbenzyl (meth)acrylate, 3-vinylbenzyl (meth)acrylate, 2,2-bis(p-(meth)acryloyloxyphenyl)hexafluoropropane, 2,2-bis(m-(meth)acryloyloxyphenyl)hexafluoropropane, 2,2-bis(o-(meth)acryloyloxyphenyl)hexafluoropropane, 1,4-bis(2-(meth)acryloyloxyhexafluoroisopropyl)benzene, 1,3-bis(2-(meth)acryloyloxyhexafluoroisopropyl)benzene, 1,2-bis(2-(meth)acryloyloxyhexafluoroisopropyl)benzene, 1,4-bis(2-(meth)acryloyloxyisopropyl)benzene, 1,3-bis(2-(meth)acryloyloxyisopropyl)benzene, 1,2-bis(2-(meth)acryloyloxyisopropyl)benzene and the like. These can be used alone or in admixture thereof.
Among the above crosslinkable compounds (E), because optical property and mechanical strength can be greatly imparted to the ocular lens material I and handling is easy, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, diallyl adipate and diethylene glycol diallyl ether are preferable. In particular, ethylene glycol di(meth)acrylate and diethylene glycol diallyl ether are preferable.
In order to impart sufficient optical property and mechanical strength to the ocular lens material I, it is desired that the amount of the crosslinkable compound (E) in the monomer mixture is at least 0.01% by weight, preferably at least 0.05% by weight. In order to remove fear that flexibility of the ocular lens material I is lowered although mechanical strength is imparted to the ocular lens material I, it is desired that the amount of the crosslinkable compound (E) in the monomer mixture is at most 15% by weight, preferably at most 10% by weight.
The above monomer mixture may further contain an ultraviolet-ray absorbing agent in order to improve ultraviolet-ray absorbability of the ocular lens material I.
Examples of the ultraviolet-ray absorbing agent are a benzotriazole ultraviolet-ray absorbing agent such as 2-(2xe2x80x2-hydroxy-5xe2x80x2-methacryloxyethyleneoxy-t-butylphenyl)-5-methylbenzotriazole or a compound represented by the formula (III):
wherein Z1 is hydrogen atom, a halogen atom such as chlorine atom, bromine atom or iodine atom, an alkyl group having 1 to 6 carbon atoms or an alkoxyl group having 1 to 6 carbon atoms, and each of Z2 and Z3 is independently hydrogen atom or an alkyl group having 1 to 6 carbon atoms, such as 2-(2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)benzotriazole, 5-chloro-2-(3xe2x80x2-t-butyl-2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)benzotriazole or 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethyl)-4-methylphenol; a benzophenone ultraviolet-ray absorbing agent such as 2-hydroxy-4-methoxybenzophenone or 2-hydroxy-4-octoxybenzophenone; a salicylic acid derivative ultraviolet-ray absorbing agent; a hydroxyacetophenone derivative ultraviolet-ray absorbing agent; and the like. Among them, the benzotriazole ultraviolet-ray absorbing agent is preferable from the viewpoint of ultraviolet-ray absorbability. In particular, the compound represented by the formula (III), such as 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethyl)-4-methylphenol is preferable.
The above ultraviolet-ray absorbing agent may or may not have a polymerizable group, and is not particularly limited.
It is desired that the amount of the above ultraviolet-ray absorbing agent in the monomer mixture is at least 0.01% by weight, preferably at least 0.05% by weight in order to impart sufficient ultraviolet-ray absorbability to the ocular lens material I. Also, it is desired that the amount is at most 5% by weight, more preferably at most 3% by weight in order to prevent relative decrease in other properties and induction of polymerization inhibition caused by excessive addition.
In order to produce the ocular lens material I of the present invention, a siloxane-containing polymer can be prepared by polymerizing the above monomer mixture.
In preparing the above siloxane-containing polymer, a radical polymerization initiator, a photo sensitizer and the like are usually added first to the monomer mixture obtained by adjusting kind and amount of monomers. They are added in accordance with a radical polymerization method such as a thermal polymerization method or a photo polymerization method mentioned below, wherein radical generated in an active unsaturated group is subjected to polymerization reaction.
Typical examples of the radical polymerization initiator are a thermal polymerization initiator such as azobisisobutyronitrile, azobisdimethylvaleronitrile, benzoyl peroxide, t-butyl hydroperoxide, cumene peroxide; a benzoin photo polymerization initiator such as methylorthobenzoyl benzoate, methylbenzoyl formate, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether or benzoin-n-butyl ether; a phenone photo polymerization initiator such as 2-hydroxy-2-methyl-1-phenylpropane-1-one, p-isopropyl-a-hydroxyisobutylphenone, p-t-butyltrichloroacetophenone, 2,2-dimethoxy-2-phenylacetophenone, xcex1,xcex1-dichloro-4-phenoxyacetophenone or N,N-tetraethyl-4,4-diaminobenzophenone; 1-hydroxycyclohexyl phenyl ketone; 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime; a thioxanthone photo polymerization initiator such as 2-chlorothioxanthone or 2-methylthioxanthone; dibenzosvarron; 2-ethylanthraquinone; benzophenone acrylate; benzophenone; benzyl; and the like.
The photo sensitizer is not activated independently by irradiation of ultraviolet-ray. However, when used together with a photo initiator, the photo sensitizer effects as a promotor and show more excellent effects than the photo initiator alone. Examples of the photo sensitizer are 1,2-benzoanthraquinone; an amine compound such as n-butylamine, di-n-butylamine or triethylamine; tri-n-butylphosphine; allylthiourea; s-benzylisothiuronium-p-toluenesulfinate; diethylaminoethyl methacrylate; and the like.
The radical polymerization initiator and the photo sensitizer can be suitably selected and used alone or in admixture thereof. It is desired that the amount thereof is about 0.002 to 2 parts by weight (hereinafter referred to as xe2x80x9cpart(s)xe2x80x9d), preferably about 0.01 to 1 part, based on 100 parts of the total amount of the monomer mixture.
In the radical polymerization method, only a radical polymerization initiator and a photo sensitizer may be used for polymerization of the monomer mixture. However, a diluent can be also used, for instance, to improve compatibility of each monomer.
Typical examples of the diluent are an alcohol such as methanol, ethanol, propanol, butanol, pentanol or hexanol; a ketone such as acetone or methyl ethyl ketone; an ether such as diethyl ether or tetrahydrofuran; and the like. These can be used alone or in admixture thereof.
Among the diluents, an alcohol having 1 to 6 carbon atoms is preferable since the monomer mixture gains excellent solubility. In particular, n-propanol, n-butanol and n-pentanol are preferable.
The monomer mixture is admixed with the diluent according to the following proportion. That is, in order to dissolve the monomer mixture in the diluent sufficiently, it is desired that the weight ratio of the monomer mixture to the diluent, the monomer mixture/the diluent, is at most 90/10, preferably at most 80/20. In order to remove fear that the aimed polymer becomes cloud in white to lower optical property and the polymer lacks mechanical strength, it is desired that the above weight ratio is at least 30/70, preferably at least 50/50.
The ocular lens material I can be prepared by means of every conventional method. However, from the viewpoint of achieving maximum benefit from the properties of the ocular lens material I, it is particularly preferable to produce a lens by preparing a siloxane-containing polymer according to polymerization reaction after injecting the above monomer mixture and, if necessary, the above diluent into a mold composed of two parts, one part corresponding to the front shape of a lens, such as, a contact lens or an intraocular lens, and the other part corresponding to the back shape of the lens, and sealing the mold. In case of producing an intraocular lens, a mold having a shape corresponding to a one-piece intraocular lens in which an optic and haptics are united with each other may be used. Also, a mold having a shape corresponding to the optic and a mold having a shape corresponding to the haptics may be used.
After a monomer mixture and, if necessary, a diluent are injected into the mold, polymerization reaction is carried out to give a siloxane-containing polymer. Any usual method can be employed for the polymerization without particular limitation.
The methods for the polymerization are, for instance, a thermal polymerization method, wherein a mixture of a monomer mixture containing the above radical polymerization initiator and, if necessary, a diluent, is heated at about 30xc2x0 C. to 60xc2x0 C. for several hours to several 10 hours to polymerize the mixture, and then the temperature of reaction system is gradually increased to about 120xc2x0 C. to 140xc2x0 C. over several hours to ten and several hours to complete the polymerization; a photo polymerization method, wherein the above mixture is irradiated with light ray such as ultraviolet-ray, which has wavelength corresponding to absorption band of activation of the radical polymerization initiator and then, the monomer mixture is polymerized; and a combination method of thermal polymerization and photo polymerization.
When the thermal polymerization method is carried out, the above mixture can be heated in a thermostat container or a thermostat room, and can be irradiated with electromagnetic wave such as microwave. The temperature of the mixture may be increased stepwise. When the photo polymerization method is carried out, the photo sensitizer may be further added to the mixture.
The thus-obtained siloxane-containing polymer is put out from the mold to give the ocular lens material I of the present invention.
The above ocular lens material I can be subjected to mechanical process such as cutting process or polishing process as occasion demands.
The above ocular lens material I has excellent properties sufficient and suitable for an ocular lens material. However, the above siloxane-containing polymer is subjected to saponification to obtain a material whose wettability is further improved.
That is, the ocular lens material of the present invention, hereinafter referred to as ocular lens material II, comprises a polymer prepared by saponifying a siloxane-containing polymer obtained by polymerizing a monomer mixture containing (A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and (B) a vinyl ester of lower fatty acid as essential components. The process of the present invention is characterized by the above saponification.
The saponification in the present invention is to form vinyl alcohol as mentioned below by subjecting units derived from the vinyl ester of lower fatty acid (B) in the polymer, which can decompose by saponification, to alkali treatment with an alkaline compound or to acid treatment with, for instance, sulfuric acid according to the conventionally known saponification method of polyvinyl ester. In saponification by the acid treatment, however, there are defects that saponification speed is late, uniform saponification is difficult and that side reaction occurs. For these reasons, saponification by the alkali treatment is preferred. By saponification, hydrophilic property, in other words surface wettability, can be imparted to the ocular lens material II without much increase of water content.
wherein R is the same as the above.
Examples of the alkaline compound used for the alkali treatment are ammonia, an alkaline metal hydroxide, an alkaline earth metal hydroxide and the like. Concrete examples of the alkaline compound are ammonium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide and the like. Because most alkaline compounds are solids, it is preferred that these alkaline compounds are dissolved in water, an alcohol, an ether or the like to give an alkaline solution and the alkaline solution is used for saponification.
Examples of the alcohol are methanol, ethanol, propanol, butanol and the like. Examples of the ether are diethyl ether, tetrahydrofuran and the like.
Among the alkaline solutions of alkaline compound used for saponification, those obtained from an alcohol are preferable. In order to carry out saponification efficiently, a methanol aqueous solution of sodium hydroxide having a concentration of 0.01 to 1 mol/L is more preferable. In particular, a methanol aqueous solution of sodium hydroxide, in which the volume ratio of methanol to water, methanol/water, is 30/70 to 90/10, is preferable.
An ocular lens material can be subjected to dyeing in case where saponification is carried out by alkali treatment in the present invention.
Specifically, a siloxane-containing polymer is prepared as mentioned above, then immersed and swollen in a mixture obtained by dispersing, or dissolving a dye in an organic solvent such as methanol, ethanol or 2-propanol, and non-reacted residual monomers in the siloxane-containing polymer are eluted while the dye is dispersed in the polymer at the same time. The dye can be fixed to the siloxane-containing polymer in subsequent saponification by alkali treatment.
There is no particular limitation for the above dye. Preferable examples thereof are, for example, reactive dyes such as C. I. Reactive Black 5, C. I.: standing for xe2x80x9cColor Indexxe2x80x9d, hereinafter referred to as the same, C. I. Reactive Blue 21, C. I. Reactive Orange 78, C. I. Reactive Yellow 15, C. I. Reactive Blue 4, C. I. Reactive Red 11, C. I. Reactive Yellow 86, C. I. Reactive Blue 163, C. I. Reactive Red 180, and the like. The amount of the dye is not particularly limited as long as it is used in such an amount that sufficient dyeing of the ocular lens material II can be achieved.
The siloxane-containing polymer is subjected to saponification by immersing the polymer in the above alkaline solution or the above solution of acidic compound.
The temperature in saponification is not particularly limited. In general, it is desired that the temperature is about 0xc2x0 C. to about 100xc2x0 C., preferably about 10xc2x0 C. to about 70xc2x0 C.
The treatment time for saponification, which is not determined as a whole, can be changed depending on kind of alkaline compound and acidic compound, concentration of alkaline compound and acidic compound, or temperature of saponification. However, it is desired that the treatment time is at least 0.1 hour, preferably at least 0.5 hour in order to improve hydrophilic property of the ocular lens material II effectively. Also, it is desired that the treatment time is at most 30 hours, preferably at most 15 hours, in order to remove fears that an inappropriate material for an ocular lens is produced because the material becomes cloud in white to lower transparency, or because mechanical strength thereof is lowered, and that working efficiency is lowered due to extended treatment time.
The saponified polymer can be boiled in physiological saline (0.9% sodium chloride aqueous solution) for several hours.
Further, it is also possible to carry out the above saponification after photo-irradiation to the prepared siloxane-containing polymer in the present invention.
The ocular lens material II obtained by the saponification of alkali treatment after photo-irradiation to the siloxane-containing polymer has further increased surface wettability.
It is preferable to carry out photo-irradiation before the saponification to a siloxane-containing polymer as mentioned above, but there, is no particular limitation for the condition of the siloxane-containing polymer as long as the polymer is dried or swollen by an extraction solution employed for removing residual monomers during extraction process.
It is desired that light to be irradiated is ultraviolet ray having a wavelength of preferably at most 380 nm, more preferably at most 300 nm from the viewpoint of efficient improvement of wettability. It is particularly preferable to irradiate ultraviolet ray having a wavelength near 185 nm and ultraviolet ray having a wavelength near 250 nm simultaneously.
It is desired that the photo-irradiation time is 0.1 to 600 minutes, preferably 1 to 60 minutes from the viewpoint of efficient improvement of wettability without affecting productivity to produce a desired ocular lens from the ocular lens material II.
Either of the above steps may precede when both of the steps are employed together, one step being such that a siloxane-containing polymer is immersed and swollen in a mixture obtained by dispersing, or dissolving, a dye in an organic solvent to elute residual monomers in the siloxane-containing polymer which did not react while the dye is dispersed in the polymer at the same time, and the other step being such that the siloxane-containing polymer is irradiated with photo. When the photo-irradiation step is carried out after the elution step, light may be irradiated after a sample is dried for increased efficiency of photo-irradiation.
The ocular lens material I of the present invention is most suitable for a soft ocular lens material in particular. This is because the ocular lens material I has excellent flexibility, particularly shape recovery, in addition to advantages of conventional soft ocular lens materials, such as high oxygen permeability, superior lipid-stain resistance and excellent wettability. The reason why a material excellent in shape recovery is suitable for a soft ocular lens material can be seen when a material inferior in shape recovery is taken into account. When used as a contact lens, a material inferior in shape recovery disturbs stable eyesight immediately after wearing lenses, causes uncomfortable feeling to patients during wearing lenses, and further, induces troubles in eyeball. Meanwhile, when an ocular lens material is used as a soft intraocular lens, the best advantage of the soft intraocular lens resides in the fact that incision of eyeball can be extremely small since the lens is foldable when inserted in the eye. However, when an ocular lens material is inferior in shape recovery, wide incision is therefore necessary because the material is difficult to fold. In addition, when shape recovery is inferior, it is difficult for a lens to recover its original shape after insertion in the eye and function as a lens is not achieved, resulting in lowering of eyesight. Accordingly, the ocular lens material I of the present invention is very suitable for an ocular lens material for the reason that it has excellent flexibility, particularly shape recovery, in addition to high oxygen permeability, superior lipid-stain resistance and excellent wettability.
Furthermore, in recent growing development of soft ocular lens materials with high oxygen permeability, use of a silicon-containing component is becoming essentially important for high oxygen permeability. However, though high oxygen permeability is imparted to the material, the material becomes extremely vulnerable to stain by lipid and inferior in hydrophilic property when used for an ocular lens because of high affinity of the silicon-containing component with a lipid component. Such characteristics are also inappropriate for an ocular lens material. On the contrary, the ocular lens material II of the present invention has not only high oxygen permeability and excellent flexibility as typified by shape recovery, but also excellent hydrophilic property, surface wettability in other words, and lipid stain resistance at the same time due to saponification, showing most suitable properties for an ocular lens material all together.
Next, the ocular lens material and the process for producing the same of the present invention are explained in detail, but the present invention is not limited thereto.

Ocular lens materials and process for producing the same