JPH06345B2 - Method for molding photosensitive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for molding a photosensitive composition, particularly a method for molding a plastic into a sheet.

(b) Conventional Technology There are various conventional methods for molding plastic into a sheet as follows. The sheet here is used as a concept including a film, but generally, the thickness is 0.
The sheet is 1 mm or more and the film is less than 1 mm.

Extrusion molding method In general, a thermoplastic resin is melted by heating, extruded from a wide so-called T-shaped die having a narrow slit, and pressed against a cooling roll to be cooled and cured. This is called the casting method in the extrusion molding method.

Further, a so-called inflation method in which the material is extruded from a ring-type gap, air is blown from the center of the ring to form a valve, and the valve is folded into a sheet, belongs to this category.

In particular, the casting method using a T-shaped die has a great advantage in that a highly accurate sheet can be manufactured in a large volume in the extrusion method, and is most popular as a means for molding a thermoplastic resin into a sheet shape. It is a molding method.

Solution casting method (casting method) In this method, a plastic that is soluble in a solvent is dissolved in a solvent, the solution (called a dope) is supplied to a hopper, and the metal drum is fed through a narrow gap provided under the hopper. Alternatively, it is a method in which the sheet is cast on a metal belt and is rotated as it is to volatilize the solvent to solidify the sheet, and the sheet is peeled from the metal surface and taken out.

In this method, the sheet surface is well ground and solidified by contacting the metal surface which is kept smooth, so that a sheet having a very smooth and excellent gloss can be obtained, and the vertical and horizontal orientations are almost recognized. It is a remarkable feature that there is no place. It is said to maintain a level superior to any other process in thickness accuracy. The photographic film is made by this method using cellulose acetate.

Calendering method This method supplies thermoplastic resin between heated multi-stage rolls, repeats kneading, and finally introduces molten resin between two rolls for determining thickness, and solidifies by cooling. Is a method of manufacturing a sheet.

According to this method, a wide sheet can be manufactured with high efficiency. The most popular plastic sheet produced by this method is a soft and rigid polyvinyl chloride sheet.

(c) Problems to be Solved by the Invention The outline of the method for molding plastic into a sheet has been described above, but each has the following drawbacks.

In the extrusion molding method (1), a thermoplastic resin obtained by requiring a large amount of energy is further melted by further applying heat energy and molded. It is also possible to produce multilayer sheets by melt extrusion lamination, but not for substrates that should not be in contact with high temperatures. Insulating strain occurs in the sheet during heat molding, but it is difficult to completely relax it even if annealing is applied, and it is not suitable for applications where dimensional stability during heating is strictly required. is there.

Further, compared with the solution casting method, since the sheet thickness is inferior in uniformity and surface smoothness, there are drawbacks such as being unsuitable for production of products that are strictly required, such as photographic film. Have

In the solution casting method, sheeting equipment for obtaining an accurate sheet becomes very expensive, and if the solvent recovery equipment and safety equipment are included, the total equipment investment requires a huge amount. Also, the higher the production speed, the more expensive the equipment becomes, and the production cost becomes very high. In addition, the plastics that can be used for sheeting by this method are limited. Currently, most of them are cellulose acetate, and as the others, only a small part of polyvinyl chloride sheet, and some polyvinyl alcohol, polycarbonate, etc. There are too many examples to see. However, it is difficult to form an extremely thin sheet or a thick sheet, and there is a drawback that it can be formed only in the range of 50 to 300 μ at best.

In the calendar molding method, the material is limited to the extent that only soft and hard polyvinyl chloride is applicable to the thermoplastic synthetic resins. Also, this molding method is a process that consumes a large amount of energy similarly to the extrusion molding method, has higher productivity than the extrusion molding method, and requires only a small amount of a processing aid such as a stabilizer, so that the cost is low. Although it has the advantage of being inexpensive, it has drawbacks in that it is inferior to the polyvinyl chloride sheet produced by the extrusion method in terms of quality and compatibility with a variety of small rods.

Because of this situation, there was no other choice than a solution casting method to form a very uniform film that had excellent surface gloss and was smooth and free of foreign matter, such as a photographic film. There has been a strong demand in the industry for the development of a process for manufacturing the product of (1) above, which overcomes the drawbacks of the conventional process and is cheaper, safer, and has a wide range of applications, and is highly efficient.

(d) Means for Solving Problems To summarize the shortcomings of the existing process, that is, the fundamental problems to be solved, the materials must be heated and melted and kneaded during molding.

A large amount of solvent must be used during molding and must be recovered.

It means that.

The present inventor has completed the method of the present invention as a result of earnest research, and has developed an epoch-making sheet manufacturing process in which a photosensitive composition is applied as a method using neither heat nor solvent. The point of the present invention is that the curing defect due to air, which has been generally regarded as the greatest drawback of the photosensitive composition, is used in reverse. The point is that the photosensitive composition is spread on the metal surface and irradiated with light from the side opposite to the metal surface to cure. Therefore,
A sheet having an uncured surface that has been exposed to air after irradiating light is peeled off from the metal surface and then the uncured portion is brought into close contact with the metal surface, and light is irradiated from the uncured surface, or Similarly, the sheet having the other uncured surface peeled off from the metal surface is pressure-bonded to each other to integrate them, and then light is irradiated from both sides. The curing is completed because the air is completely shut off.

Here, in any of the above methods, it is important that both surfaces of the sheet are completed by replicating the metal surface. To simply block the air, for example, the photosensitive composition spread in a film form with transparent polyester film layers on the upper and lower sides is further sandwiched between smooth glass plates from above and below, and light is irradiated from both surfaces. By curing or by replacing either one of the transparent polyester film layers in the above example with a metal surface and then irradiating light from the polyester film layer to cure, a completely cured sheet can be obtained. can get. However, in the case of the sheet thus obtained, the polyester film is a replica on both sides in the case of the former, and in the case of the latter, either one side is the surface of the polyester film similarly transferred. Usually, reaction heat is generated during photocuring, and the heat causes the polyester film to wavy. Therefore, it has been found that a sheet excellent in smoothness cannot be obtained by such a method.

There is also a method in which a photosensitive composition is spread on a metal surface and the surface of the composition is cured in a nitrogen or carbon dioxide gas atmosphere. In the case of this method, the viscosity of the photosensitive composition is lowered to improve the spreadability of the resin, and when molding into a thin film, a relatively smooth surface can be obtained even on the side not in contact with the metal roll, When the viscosity is increased for molding, flow marks of the resin solution remain and the smoothness of the solution casting method cannot be obtained.

Any of the above methods is a known method, and it is necessary to use a polyester film, nitrogen gas or carbon dioxide gas is required, and extra costs are required. have.

From the above, in order to obtain a sheet with excellent surface gloss and smoothness, it is important to complete curing with both surfaces of the sheet in close contact with the smooth metal surface. It can be seen that the sexual composition is based on the premise that curing is inhibited by the presence of air. In this case, the metal surface is preferably in the form of a metal roll or a metal belt for continuous industrial production.

The photosensitive composition refers to a composition that is cured by irradiation with light, and is not particularly limited and can be applied to all photosensitive compositions. However, although it is necessary that the curing is inhibited by the presence of air (oxygen), there is no problem because it is normally inhibited except for exceptional cases. The viscosity of the composition is not particularly limited as long as it can be spread.

The photosensitive composition may be not only a monomer but also an oligomer, a prepolymer or the like as long as it is cured by irradiation with light, and a monomer having an acryloyl group or an allyl group as a functional group is common. .

For example, HEMA (2-hydroxyethyl methacrylate), N-methyl acrylamide, etc. are available.

Further, the composition need not be a single composition, but may be a mixture of various photosensitive compositions.

Moreover, you may mix a high molecular polymer with this photosensitive composition. Examples of the polymer to be mixed include polyamide-based ones. Among them, N-methoxy-6-nylon was found to have transparency even in the cured film, and was found to have a sheet forming ability.

The metal roll refers to a cylindrical drum having a metal surface.

Spreading refers to placing the composition on a roll by casting, which is usually discharged from a narrow slit-shaped inlet.

The side opposite to the metal roll is a method of irradiating the spread composition with light, and refers to a direction from the outside to the roll when viewed from the roll, not from the metal side.

The light here is basically ultraviolet light, but any light that can be used for curing visible light or the like may be used.

The reason why such a method is possible is that when the photosensitive composition is irradiated with light, the surface of the surface which is in contact with air undergoes curing inhibition by oxygen, so that the curing is very slow and the metal surface side is reflected. This is because it is considered that the resin will cure quickly due to the influence of light. Further, it is considered that air dissolves and permeates from the surface of the composition before curing and is inhibited thereby, but this dissolution and permeation does not reach the metal side.

The result of the inventor's experiment is shown in FIG. In FIG. 1, the horizontal axis represents time (seconds) and the vertical axis represents the spread thickness of the composition. In this case, the spread thickness is 3000μ. Therefore, the point where the thickness is 0 is the side in contact with air,
The point of is the side in contact with the metal roll. Curve (11) is the gelling curve and curve (12) is the curing curve. In this example, the point about 400μ from the surface is the fastest (about 30 seconds)
Gelled and cured. Next, gelation proceeded in the vertical direction of the layer, and after about 60 seconds had elapsed, gelation and curing started from the metal surface, and in about 120 seconds, the surface layer was completely cured leaving about 20 μ of the surface layer. In the figure, (13) shows a solution state, (14) shows a gel state, and (15) shows a solid state.

As described above, when exposed to air, a certain thickness from the surface is not cured (or curing is extremely slow), and thus the method of the present invention is possible.

There are two kinds of specific methods of the method of the present invention, each of which will be described below.

First of all, two metal rolls are arranged close to each other, a photosensitive composition is spread on the rolls, and the spread composition on both rolls is irradiated with light from the side opposite to the metal rolls. This is a method in which the side in contact with the roll is cured and the partially cured composition is guided by the rotation of the roll into the gap between the two rolls, both compositions are bonded and integrated into a sheet, and then the composition is completely cured by irradiating light again.

In the first method, the metal roll to be prefixed at the time of curing and the roll for forming the adhesive integral sheet can be implemented separately.

The second is to place two metal rolls close to each other, spread the composition on one roll, irradiate light from the side opposite to the metal roll, cure the side in contact with the metal roll, and rotate the roll. The partially cured composition is introduced into the gap between both rolls, the uncured side is passed through the gap so as to come into contact with the other metal roll, and after passing through, the light is irradiated from the side opposite to the other metal roll and is in contact with the metal roll. This is a method in which the side is cured, and then it is completely cured by irradiating with light again.

In order to shorten the production time of the above two specific methods, the intensity of the ultraviolet rays to be irradiated is increased or a composition having a fast curing rate is used. Also, the ultraviolet irradiation range (area)
Can be increased and the composition can be exposed to UV light for a longer time. For example, increasing the radius of the metal roll,
Instead of one metal roll, two rolls having a metal belt may be used.

The method of the present invention is easy to stop and start because the energy for curing polymerization is light and not heat, and it can be partially cured. That is, in the case of polymerization by heat, even if the heating device is turned off, the temperature does not immediately reach room temperature, so immediate stop of the polymerization is impossible. In addition, the start of operation similarly takes time to raise the temperature to a predetermined temperature. In the case of light, these are very smooth.

Further, in partial curing, even if it is locally heated by heat or the like, since the vicinity thereof is inevitably heated, partial curing in the true sense cannot be performed. However, if light is used, it is possible to cure only a specific portion by using various shapes of light blocking tools.

(e) Example FIG. 2 is a schematic sectional view showing an example of the sheet forming method of the present invention. Two metal rolls (1) are arranged close to each other, an upper ultraviolet irradiation device (2) is provided above them, a hopper (3) is provided on each metal roll, a lower ultraviolet irradiation device (4) is provided below, and a pinch roller is further provided below. (5) is provided.

The photosensitive composition (6) is spread and fed onto the metal roll from the two hoppers (3). Since the metal roll (1) is rotating, each photosensitive composition (6) advances toward the metal point (7) of both metal rolls (1). Proximity to hopper (7)
In the meantime, each photosensitive composition (6) is irradiated with ultraviolet rays by the upper ultraviolet irradiation device (2), and is cured from a certain depth from the surface and on the metal surface as described in FIG. Go for the first time In other words, the photosensitive composition (6) is gradually introduced into the approaching point (7) within a time such that the surface is not completely cured and the metal surface side is completely cured.

By this ultraviolet irradiation, the metal surface side is completely cured, so that the metal side surface is finished as smooth as the metal surface. Naturally, the surface of the metal roll is finished with a required degree of accuracy. This finishing method may be an ordinary method, for example, the same as the metal roll or the like in the solution casting method described above.

In this way, the composition in which the surface side is uncured and the roll side is cured is laminated at the proximity point (7) and the thickness is adjusted to be integrated. This is pulled by a pinch roller (5) and wound on the downstream side, or cut into sheets and accumulated. Between this metal roll (1) and the pinch roller (5),
The inside of the laminated sheet is completely cured by irradiating it with ultraviolet rays again. In this figure, ultraviolet rays are radiated from both sides, but this may be only from one side.

This completes sheet (8). Of course, it is free to perform stretching and other processing that is usually performed on the sheet.

By this method, it is possible to easily manufacture a sheet having very smooth surfaces on both sides, which has been very difficult in the past.

Furthermore, according to this method, another film or sheet, or another photosensitive composition is introduced from above the proximity point (7),
A laminated structure is also easy. In this case, it is also possible to manufacture a non-transparent material that cannot be made with a photosensitive resin. That is, even if the sheet in the middle does not transmit light at all, it is irrelevant to the irradiation on the metal roll (that is, does not block the ultraviolet irradiation),
In the irradiation after bonding, the uncured composition is completely cured by irradiation from both sides.

Furthermore, other substances, such as powder or granules for decoration or imparting functionality, and various shapes (lace-shaped objects,
Specimens such as plants and butterflies) can be sandwiched.

It can be said that FIG. 3 is conceptually a method in which the function of the metal roll in FIG. 2, that is, the imparting of smoothness to the surface and the adhesive integration are separated. Metal roll for adhesive integration (10)
Is placed in the center, and a metal roll (1) for finishing one side to the left and right of it is arranged, and a hopper (3) and a roll (1) are surrounded by it for at least half a circumference, and an ultraviolet irradiation device ( 2) is installed, and the roll (9) is installed in such a positional relationship that the uncured surface is not in contact. These devices are arranged in such a positional relationship that the composition reaches from the hopper (3) to the metal roll (1), the roll (9), the metal roll (10) and finally the pinch roll (5).

By doing so, in addition to the same advantages as in the case of the embodiment described with reference to FIG. 2, there are the following advantages.
That is, in FIG. 2, if the composition used has an affinity for the surface of the metal roll (1), and if a slight peeling stress is applied, the stress causes the two compositions to bond to each other. There is a possibility of acting as a stress to peel off both compositions below the close point (7). However, in the case of the method of FIG. 3, peeling and adhesive integration are not performed close to each other, so there is no fear of this. Further, since a sufficient distance for irradiation can be obtained, productivity can be improved. Further, during the process of inducing the partially-cured composition and guiding it to the metal roll (10), a step of incorporating a partially-cured device on the uncured surface or spraying a fine powdery colorant or magnetic substance It has advantages such as easy incorporation.

FIG. 4 is a schematic sectional view showing another example. In this example, two metal rolls (1) are vertically arranged close to each other.
Then, the composition (6) is spread and introduced from the uppermost portion, and the metal roll (1) is rotated and guided to the proximity point (7) as in the above example. Then, ultraviolet rays are irradiated between the introduction point and the proximity point (7) to cure the metal roll side.

Up to this point, the procedure is the same as in the above example, but the partially cured sheet-like body is transferred to another metal roll instead of being laminated here. At this time, it is necessary that the side prefixing the metal surface is inverted. Then, ultraviolet rays are similarly irradiated to cure the metal roll side.

Then, ultraviolet rays are irradiated again until the pinch roller (5) to completely cure. In this example, the ultraviolet irradiation has three stages.

(f) Effects of the Invention The sheet forming method of the present invention has the following remarkable effects.

 A sheet with a very smooth surface can be manufactured.

 The manufacturing equipment itself is very simple and inexpensive.

Since no solvent is required, there is no danger to humans or fire.

Since it is not necessary to collect the solvent and the like, the entire device becomes compact.

Easy on / off of polymerization and partial polymerization (curing).

There are many kinds of photosensitive compositions, and various compositions can be selected in order to obtain physical properties according to needs.

Since there is no need to use a solvent or a high temperature, it is possible to carry out laminating with a material that does not like a high temperature or a solvent.

Even if the composition changes, it can be operated with simple adjustment without the need for dedicated equipment. A normal extrusion molding machine, a solution casting method apparatus, and the like are dedicated machines, so that the resin cannot be easily changed.

[Brief description of drawings]

FIG. 1 is a graph showing a cured state, FIG. 2 is a schematic sectional view showing an embodiment of the method of the present invention, FIG. 3 is a schematic sectional view showing another example of the method of the present invention, and FIG. It is a schematic sectional drawing which shows another example. DESCRIPTION OF SYMBOLS 1 ... Metal roll 2 ... Upper ultraviolet irradiation device 3 ... Hopper 4 ... Lower ultraviolet irradiation device 5 ... Pinch roller 6 ... Composition 7 ... Proximity point 8 ... Sheet 11 ... Gelation curve 12 ... Curing curve 13 ... Solution state 14 ... Gel State 15 ... Solid state

Claims (4)

[Claims] 1. A molding of a photosensitive composition, which comprises spreading a photosensitive composition which is hardened by the presence of air on a metal surface and irradiating light from the side opposite to the metal surface to cure the photosensitive composition. Method. 2. A composition in which two metal rolls are disposed in close proximity to each other, a photosensitive composition which is subjected to curing inhibition by the presence of air is spread on the rolls, and the composition is spread on both rolls from the side opposite to the metal rolls. Irradiate the object with light to cure the side in contact with the metal roll, guide the partially cured composition by the rotation of the roll into the gap between both rolls, form an adhesive integral sheet of both compositions, and then irradiate with light again The method for molding the photosensitive composition according to claim 1, wherein the method is to completely cure the photosensitive composition. 3. Two metal rolls are arranged in close proximity to each other, and a photosensitive composition, which is subjected to curing inhibition by the presence of air, is spread on two metal rolls, which are separately arranged on the left and right sides with the rolls at the center. Then, the composition spread on both rolls is irradiated with light from the side opposite to the metal rolls to cure the side in contact with the metal rolls, and then each composition from the metal roll surface is rotated with the rotation of the rolls. Peel off and guide the uncured surface, which is hardened by air, between the two metal rolls located close to the center in a positional relationship so as not to directly touch an object such as an induction roll, and make both compositions into an integrated sheet. The method for molding a photosensitive composition according to claim 1, wherein the resin is completely cured by irradiation with light again. 4. Two metal rolls are arranged in close proximity to each other, one of the rolls is spread with a photosensitive composition which is subjected to curing inhibition by the presence of air, and light is radiated from the side opposite to the metal roll to contact the metal roll. Is cured, the composition partially cured by the rotation of the roll is introduced into the gap between both rolls, the uncured side is passed through the gap so as to contact the other metal roll,
The photosensitivity according to claim 1, wherein after passing, the side which is in contact with the metal roll is cured by irradiating with light from the side opposite to the other metal roll, and is then completely cured by irradiating with light again. Method of molding the composition.