JP2003103536A - Filling method for monomer mixed liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of air bubbles when a mold is filled with a polymerizable monomer mixed liquid to manufacture a lens in a high excellent article ratio, in a method for manufacturing the ophthalmic lens by filling a space formed by a mold with the polymerizable monomer mixed liquid to polymerize the polymerizable monomer mixed liquid. SOLUTION: The generation of air bubbles in the polymerizable monomer mixed liquid is prevented by using a tube type pump in the filling with the polymerizable monomer mixed liquid and providing a flow channel resistive element to the flow channel between the outlet of the pump and a mold filling port to obtain the ophthalmic lens in a high acceptable product ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ophthalmic lens by forming a lens space by a mold made of resin or the like, and polymerizing a polymerizable monomer mixed solution in the space, and particularly, a polymerizable monomer mixed solution. The present invention relates to a method of preventing bubbles from being generated when a liquid is filled in a mold.

[0002]

2. Description of the Related Art In a method for producing an ophthalmic lens by filling a space in a mold with a polymerizable monomer mixed liquid and polymerizing the liquid, a monomer is usually supplied quantitatively into the mold by using a pump, Fill. If air bubbles are mixed in the monomer mixture liquid filled in the mold during this filling, air bubbles will also enter the polymerized ophthalmic lens product, leading to a reduction in the yield rate. As a conventional technique, for example, Japanese Patent Application Laid-Open No. 8-52819 proposes a method of preventing the generation of bubbles by injecting a monomer mixture solution and assembling a male mold and a female mold under vacuum. According to this method, it is possible to surely suppress the generation of bubbles, but there is a problem that the structure of the device and the like becomes complicated and the manufacturing cost increases.

On the other hand, in order to quantitatively inject the liquid, a plunger type pump having a high quantitative accuracy is generally used, but the plunger type pump is suitable for sending a liquid having no viscosity. When a liquid having a relatively high viscosity such as a monomer mixed solution is fed, it is likely to partially stay, and in a monomer mixed solution containing a polymerization catalyst, the polymerization proceeds in the staying portion. As a result, there is a problem in that the amount of liquid delivered is not stable. On the other hand, when a tube type pump is used, the monomer mixture flows through the tube due to the ironing effect of the rotor in the pump, so there is no problem of retention, but bubbles are mixed in the monomer mixture as compared to the plunger type pump. There is a problem that it is easy to do.

[0004]

SUMMARY OF THE INVENTION The present invention has been made under the circumstances as described above, and in a method for manufacturing an ophthalmic lens by filling a mold with a polymerizable monomer mixed liquid and polymerizing the mixture, a tube is used. The purpose of the present invention is to prevent air bubbles from being mixed in when supplying and filling the polymerizable monomer mixed liquid when a formula pump is used.

[0005]

Means for Solving the Problems As a result of various investigations to achieve the above object, the present inventors have inserted a flow path resistance into a flow path between an outlet of a tube type pump and a charging port of a monomer. As a result, they have found that the inclusion of bubbles can be prevented, and have reached the present invention. That is, the present invention is a method for manufacturing an ophthalmic lens by filling a cavity with a monomer formed when a female mold and a male mold are combined and polymerizing, in which a tube type pump is used to fill the monomer mixture, Further, there is provided a method for filling a monomer mixed liquid, characterized in that a flow passage resistance is provided in a flow passage between an outlet of the pump and a filling opening of a tube for feeding the cavity space.

Of course, the tube used in the present invention must not be attacked by the monomer used, but a material is selected so that the monomer does not react in the tube. Generally, tubes made of Teflon (registered trademark), polyethylene, polypropylene, silicone, etc. are used. As these tubes, those having an inner diameter of 0.5 to 1.5 mm are used. If the diameter of the tube becomes large, it will be difficult to run out the monomer mixture liquid and it will be difficult to fill a certain amount.On the other hand, if it is too thin, it will take time to fill the monomer mixture liquid or the liquid flow at the bend of the tube. Since there is a problem such as being stopped, it is preferable to use one having a diameter within the above range.

As the liquid feeding device other than the tube type pump, there are a diaphragm type pump, a magnet type pump, a plunger type pump and the like. However, these liquid feeding devices are suitable for feeding general aqueous solutions, but when feeding a reactive liquid that is an organic solvent system, such as a polymerizable monomer mixture, it is assumed that the monomer When polymerization starts, it is necessary to replace the pump itself, and there is also the risk that metal or resin wear, etc. generated by the operation of the pump will mix into the monomer mixture, so a tube type is used for ease of maintenance. Pumps are the most preferred. In the case of the tube type pump, even if the monomer mixed solution is polymerized and clogged in the tube, it can be dealt with immediately by exchanging the tube, and it is not necessary to consider the inclusion of abraded material such as metal.

A feature of the method of the present invention is that a flow path resistance is arranged between the pump outlet and the monomer filling port in the monomer liquid feeding flow path. In order to fill the resin mold with the polymerizable monomer, the tip of a tube extending from the pump inlet is immersed in a reservoir of the polymerizable monomer mixed solution, and the tube type pump is operated to suck the monomer mixed solution. As will be described later in detail, the tube type pump feeds the monomer mixture liquid by squeezing the liquid feeding tube to make the inside of the tube a negative pressure. Since there is a certain negative pressure in the tube from the inlet of the monomer mixture to the pump inlet, there is no particular problem, but the pumping tube in the pump is repeatedly pressurized and depressurized. Liquid transfer from the pump outlet is accompanied by the largest pressure change. In other words, there is a change such that the pressure of the monomer mixture, which is given pressure inside the pump, is suddenly reduced at the moment when it is released to normal pressure from inside the pump. Happens in a normal way. When the pressure changes as described above, bubbles are easily generated in the monomer mixed liquid. Therefore, the present invention solves the problem by providing a flow path resistance after the pump outlet so as to maintain a pressurized state for a certain period from the pump outlet so as not to cause a sudden pressure change. Became possible. This flow path resistance is achieved by connecting a tube whose inner diameter is smaller than the diameter of the liquid delivery tube at the pump outlet. As for the ratio of the diameter, one having a diameter of 1/3 to 1/19 with respect to the liquid feeding tube in the pump is used. If this diameter is larger than 1/3, the pressure cannot be kept sufficiently raised, so there is no effect of preventing bubble generation, and if it is smaller than 1/19, the flow path resistance becomes excessive and the dispensing time becomes longer. Since problems such as lengthening and disconnection of tube joints occur, it is preferable to set it within the above range. Particularly preferably 1/5 to 1/1
The range is 2.

Further, the length of the flow path resistance can be set arbitrarily depending on the balance with the diameter, but is usually between 2 cm and 25 cm. If the length is 2 cm or less, passage of the flow path resistance occurs instantaneously, so it is difficult to obtain the pressurizing effect in the tube due to the flow path resistance, and the effect of preventing bubble generation tends to be insufficient. If it is set to 25 cm or more, the flow path resistance becomes excessively large or has a useless length. Particularly preferably, it is in the range of 5 cm to 15 cm. The length is set longer when the ratio of the pipe inner diameter to the flow resistance to the liquid feeding tube is large, and set shorter when the ratio is small.

As the tube, a tube from the polymerizable monomer mixed liquid storage tank to the pump inlet, a liquid feeding tube in the pump, a tube from the pump outlet to the filling port to the resin mold, and the flow path resistance of the present invention provided therebetween There is a tube. The materials of these tubes may be different or the same. These tubes may be selected from any material as long as they are attacked by the monomer of the polymerizable monomer mixed solution or are not reactive as described above, but the liquid feeding tube in the pump will be described later. Since the material is squeezed in the pump, for example, silicone, Teflon, etc. are used as the material having elasticity and durability. Other tube materials may be selected from materials such as polyethylene and polypropylene other than the above.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be specifically described below with reference to the above contents with reference to the accompanying drawings.

FIG. 1 is a diagram showing the outline of the method of the present invention. The tube type pump 1 has a drive shaft 2 as shown in FIG.
Is rotated by a motor, and a plurality of rotors 3 provided around the drive shaft 2 rotate in conjunction with the drive shaft 2 and rotate at the same time. Drive shaft 2 and rotor 3
Is housed in a cylindrical recess 6 formed in the case portion 5 of the pump, and the liquid feeding tube 4 made of an elastic material such as silicone or Teflon is used as the recess 6 and the rotor 3.
The liquid in the liquid-sending tube is transferred in the rotation direction of the drive shaft 2 by the ironing effect of the rotation and the revolution of the rotor 3, which is set in the space between them.

According to the present invention, when the polymerizable monomer mixed liquid 11 is injected into the lens cavity formed by the combination of the male die 12 and the female die 13 by using the tube type pump 1, the outlet 8 of the pump and the female die are introduced. It is based on the discovery that it is possible to prevent bubbles from being mixed into the monomer mixed liquid by inserting a flow path resistance between the filling ports 14.

The flow path resistance is preferably provided near the outlet 8 from the pump of the liquid feeding tube 4. This is because the purpose is to set the pressure state in order to suppress the pressure fluctuation near the pump outlet. As a means for inserting the flow path resistance, a flow path resistance tube 10 having an inner diameter smaller than that of the solution supply tube 4 is connected to the solution supply tube 4 to connect the pump outlet 8 and the monomer mixture filling port 14. Provide in between.
In this example, the flow path resistance tube 10 has an inner diameter of 0.25 m with respect to the inner diameter of the liquid feeding tube in the pump of 1.9 mm.
m, 10 cm in length. The tube 9 from the monomer mixed solution 11 to the pump inlet 7 and the tube 9 from the flow path resistance 10 to the filling port 14 have an inner diameter of 1 mm.

FIG. 2 shows an enlarged view of the tube type pump. The drive shaft 2 rotates in the direction of arrow 15, and the rotor 3 revolves in the direction of large arrow 17 while rotating on its axis as shown by arrow 16. The rotor 3 squeezes the liquid in the direction of the arrow 17 while pressing the liquid feeding tube 4 sandwiched between the rotor 3 and the recess 6. As can be seen from the portion 18 sandwiched between the rotor 3 and the depression 6, the liquid feeding tube is compressed by the rotor and the tube between the rotors is not compressed. Therefore, after the portion 20 released from the pressure of the rotor, the pressure is reduced and the pressure is intermittently changed by the discontinuous pumping of the rotor. Therefore, the flow path resistance 10 was used to maintain the pressurized state and suppress the generation of bubbles. The cause of air bubbles cannot be determined, but it is expected that especially highly volatile monomers in the liquid mixture of the polymerizable monomer are vaporized under reduced pressure. It should be noted that after the flow path resistance, since the intermittent pressure change as seen in the immediate vicinity of the pump is eliminated, it is difficult for air bubbles to enter even if the pressure is released, but for the tube up to the filling port 14, It is desirable to use a diameter that does not differ much from the tube diameter used for the flow path resistance. In this example, 4 times the diameter of the flow path resistance is used, but if it is 10 times or more different, the mixed solution generated from the flow path resistance is extremely released, and bubbles may be generated again at this part. Is not preferred.

(Example 1) Using a nylon resin, FIG.
The male mold 12 and the female mold 13 as shown in (1) were molded by the injection molding method. N-vinyl-2-pyrrolidone 40 parts, N, N'-dimethylacrylamide 40 parts, methyl methacrylate 20 parts, ethylene glycol dimethacrylate 0.5 part, polymerization initiator azobisdimethyl from the filling port 14 on the concave surface of the female mold 13. A mixture of 0.05 parts of valeronitrile and a polymerizable monomer was filled using a tube pump 1 as shown in FIG. The inner diameter is 1.9 m for the liquid delivery tube 4 in the pump
m, and a Teflon tube having an outer diameter of 2.5 mm was used. Further, the inner diameter is 1 mm and the outer diameter is 1.6 mm for transporting the monomer mixed liquid from the polymerizable monomer mixed liquid storage tank 11 to the inlet 7 of the tube type pump and from the flow path resistance tube 10 to the filling port 14 to the female mold 13. Teflon tube 9 was used. Pump outlet 8 and tube 9 of liquid delivery tube 4
Between, length 10 cm, inner diameter 0.25 mm, outer diameter 1 mm
The Teflon-made flow path resistance tube 10 was used. Using this filling method, from the monomer mixture storage tank 11 to the female mold 13
The monomer mixture liquid was transported to and filled therein, and the male mold 12 was fitted therein, followed by thermal polymerization at 80 ° C. for 25 minutes. No bubbles were present in the obtained ophthalmic lens. There was also no problem of partial polymerization of the monomer in the pump.

(Comparative Example 1) 0.2 inner diameter used in Example 1
Teflon channel resistance tube 1 with 5 mm and 1 mm outer diameter
A monomer mixture solution was transported, filled and polymerized in the same manner as in Example 1 except that 0 was not inserted to manufacture an ophthalmic lens. Many of the lenses were found to have air bubbles, and failed the product inspection.

[0018]

As described above, according to the method of the present invention, in the case of manufacturing an ophthalmic lens by filling the space in the mold with the polymerizable monomer mixed liquid and polymerizing the mixture, when filling the mold. It is possible to prevent bubbles from being generated, and it is possible to manufacture lenses with a high yield rate. Further, since the monomer does not stay in the pump, there is no problem that the polymerization partially proceeds in the pump even if the thermal polymerization method is adopted.

[Brief description of drawings]

FIG. 1 is a schematic diagram of the present invention.

FIG. 2 is a view showing a main part of a tube type pump used in the method of the present invention.

[Explanation of symbols]

1 tube type pump 2 drive shaft 3 rotor 4 Liquid transfer tube 5 tube type pump case 6 cylindrical depressions 9 Monomer mixture transport tube 10 Flow resistance tube 11 Monomer mixed liquid storage tank 12 male 13 female 14 Filling port

Claims (3)

[Claims] 1. A tubular pump for manufacturing an ophthalmic lens by filling a polymerizable monomer mixed liquid into a cavity formed when a female mold and a male mold are combined and polymerizing the liquid, when filling the monomer mixed liquid. And a flow path resistance is provided in the flow path between the outlet of the pump and the monomer filling opening into the cavity. 2. The method for filling a monomer mixed solution according to claim 1, wherein the flow path resistance is a flow path resistance tube having an inner diameter smaller than that of the liquid feed tube in the pump. 3. An inner diameter of the flow path resistance tube is 1/3 to 1/19 of a liquid feeding tube in the pump, and a length of the resistance tube is 2 to 25 cm. The method for filling the monomer mixed liquid of.