DE2115706A1 - Process for producing a polymer by photopolymerization and apparatus for carrying out the process - Google Patents

Description

Kabushiki Kaisha Toyota Chuo Kenkyusho, Nagoya, AiChi / Japan

Process for producing a polymer by photopolymerization and apparatus for carrying out it of the procedure

The invention relates to a method for producing a polymer by photopolymerization and an apparatus to carry out this procedure.

The photopolymerization is carried out according to conventional methods by adding a polymerizable reaction liquid such as a monomeric methyl methacrylate, Styrene or the like with a polymerization initiator such as a diacetyl compound, an iron ion compound or the like and mixed with a photosensitizer such as an organic dye. This reaction mixture is then exposed to visible light rays and / or irradiated ultraviolet rays to conduct polymerization.

Usually the external light source was used for the polymerization reaction statically over the photopolymerization reactor at a predetermined distance from the reaction medium

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arranged. Such a static light source is found in large reactors used for industrial mass production however, not very satisfactory because it is at a relatively large distance from the bottom of the reaction medium. Satisfactory results have not been obtained even when the light intensity is increased because the products obtained "are non-uniform. Attempts to avoid this problem by stirring the reaction medium have also failed. since the viscosity of the reaction medium increases sharply towards the end of the reaction, so that an effective Stirring is impossible.

It was also proposed to increase the number of light sources when using large-scale reactor vessels, see above that the irradiation becomes more effective. This measure is also not satisfactory, since the permeability for the Rays of light through the walls near the light sources adhering polymeric material is reduced. In addition, the conventional process has been a continuous one Operation poorly possible.

Accordingly, it is an object of the present invention to provide a method and to provide an apparatus which, at high yield, can produce excellent, homogeneous, industrial scale Products and can be used in continuous operation.

According to the invention, this object is achieved by a method for producing a polymer by photopolymerization, in which a reaction liquid containing the polymerizable material is filled in a transparent bag and is irradiated with an external light source,

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whereupon the polymer obtained is removed from the bag.

To achieve continuous operation, the bags filled with the reaction liquid can be attached to the Light source are passed. The device according to the invention for performing the method according to the invention comprises a transport device and light sources arranged above it. There can be bowl-shaped containers for receiving the bag may be provided. The light sources can be arranged within a tunnel and the intensity of the light sources can be larger at one end of the transport device than at the other.

In the following, the invention is explained in more detail with the aid of drawings and an exemplary embodiment.

Show it:

1 shows a partial side view of a first embodiment of the device according to the invention;

Fig. 2 is a cross section along the line H-II in Pig. I;

3 shows a partial side view of a second embodiment of the device according to the invention and

FIG. K shows a perspective partial view of the device according to FIG. 3.

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An essential aspect of the invention is that the photopolymerization reaction is carried out in reaction vessels which consist essentially of bags, sacks or sacks made of transparent material. The reaction liquid is filled into such a transparent bag, and the bag is together with its contents irradiated with light rays by means of an external light source, whereby the photopolymerization reaction takes place goes. In this way, the inventive method can be carried out very easily without a special reactor would be required. All that is required is a transparent bag and a light source. The polymer produced by this process can be further treated extremely easily. E.g. can Polymers are easily transported in the reactor bag. Because a relatively small amount of polymerizable reaction liquid can be contained in the bag, so you can easily use the entire contents of the bag to irradiate reaction liquid uniformly, so that a polymer having a high molecular weight and is produced with great homogeneity. In addition, to carry out the method according to the invention A conveyor belt or assembly line can be used, with many bags with the reaction liquid at one or the other several light sources are moved past, either simultaneously or in sequence. This will the inventive method of photopolymerization suitable for industrial mass production.

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When an assembly line system is used, a variety of light sources can be used along the direction of movement of the assembly line and these light sources can be provided so that an advantageous Light intensity profile is achieved, which allows the most advantageous irradiation.

The material of the transparent bag should be essentially unaffected by the light used for photopolymer exposure let through. Suitable translucent materials are, for example, polyethylene, polypropylene, cellulose | acetate or the like. Suitable for the process according to the invention In particular, all flexible, transparent materials that are stable, self-supporting and cohesive bag-like Able to form containers.

The size of the bags is not critical. With bag volumes of more than about 500 liters total capacity are likely however, difficulties in handling arise. Usually the bags are polymerizable after they have been filled Materials closed or sealed to prevent oxygen from entering and from the reaction takes part, whereby the Polymerxsationsreaktion could be adversely affected. "

The particular light source used depends, among other things, on the particular type of photoreaction chosen, as well as on the specific ones Light intensity and wavelength requirements. Suitable light sources are e.g. fluorescent lamps with visible Light or ultraviolet fluorescent lamps such as tungsten lamps, xenon lamps, sodium lamps or mercury lamps

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lamps. If the conveyor belt system described below is used, either a single light source or a large number of light sources can be arranged uniformly in the irradiation area Assembly line are arranged as near the take-off end of the assembly line system or vice versa. In this way, the intensity of the light irradiation may be different be made in the later reaction stage of ψ that in the first reaction stage. The mode of irradiation can be varied electrically by controlling the intensity of the light source if the light sources are arranged uniformly.

The process according to the invention is suitable for photopolymerization a wide variety of monomers, such as methyl methacrylate, Acrylonitrile, mixtures of acrylonitrile and styrene, styrene and other polymerizable materials. The method according to the invention can also be used for this purpose will graft a monomer onto a prepolymer, wherein the monomer is mixed with the prepolymer and this mixture is subjected to irradiation with light. On the other hand, a prepolymer can also be used with the method according to the invention or with the device according to the invention be crosslinked or polymerized to a higher degree.

Conventional polymerization initiators and photosensitizers can be used can be added to the reaction mixture in order to increase the efficiency of the process.

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The first embodiment of the device according to the invention is shown in Figures 1 and 2 and comprises a Bag 6, which contains a photopolymerizable reaction liquid and in a bowl-shaped vessel 5 lies. This bag 6 is moved by means of a transport device 1 through a tunnel 3 in which light sources 2 are arranged. The bags 6 are irradiated with the aid of the light sources 2 on their way through the tunnel 3. When the bags 6 have passed through the tunnel from one end to the other, the photopolymerization can take place be finished.

The transport device 1 comprises an endless belt 11, a drive roller 12 for moving the belt 11 in the direction of arrow A (Fig. 1), a tension roller 13 and two further rollers 13 '· The endless belt 11 is on the rollers 12, 13 and 13 ^r hung up. The drive roller 12 is connected to a motor, not shown. Furthermore, support rollers Ik and Ik 'are arranged at suitable intervals below the belt 11, which support it. The rollers Ik and Xk * are idle rollers which are rotated in contact with the lower surface of the belt 11. They are held on a conveyor belt substructure or frame 15. The upper region of the conveyor belt 11 carries bowl-shaped containers 5 which are moved through the reaction zone. The end of the belt 11 facing the tension roller 13 is the feed end D for the cup-shaped containers 5 and the end of the belt 11 facing the drive roller 12 is the removal end for the cup-shaped containers 5. The transport speed of the belt 11 is set so that the reaction liquid

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irradiated in the bags 5 with predetermined amounts of light is so that the polymerizable material within the duration of the exposure of the bowl-shaped container 5 to the light sources 2 exposed to sufficient irradiation and the reaction is completed.

The tunnel 3 with the light sources 2 is in the reaction area of the belt 11 arranged. The tunnel 3 comprises frame 31 and side walls 32 and a ceiling 33 'which are made of stainless steel plates can exist, which are ground and polished on their inner surface, so that a sufficient light reflection entry.

A number of cylindrical fluorescent lamps 21 are fastened in sockets 22 on the ceiling 33 along the conveyor belt 11. Further, a water-filled pipe 35 is arranged inside the tunnel 3 i ^m 'region of the holders 15 and above the conveyor belt 11, which serves for the removal of excess heat of reaction formed during the polymerization reaction by cooling water.

Furthermore, a ventilation system 4 is in the upper area of the Tunnel 3 is provided, which is used to control the tunnel temperature, serves. This ventilation device 4 comprises air outlets 44 which open into the ceiling 33. A pipeline 42 connects the air outlets 44 to a blower 41. The air outlets 44 have flaps 43 for control the air flow provided. Relatively flat boxes are used as bowl-shaped containers 5 transparent bag 6 filled with polymerizable reaction liquid is placed.

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Figures 3 and k show a modified embodiment of the device according to the invention, in which bowl-shaped containers 51 are connected to the conveyor belt. In this device, the bags 6 are charged with the polymerizable reaction liquid and placed in the container 51 at the entrance end B of the conveyor belt. The bags with their contents are passed under a number of light sources 2, whereby the photopolymerization is effected. The bags filled with the polymers obtained are ejected into a funnel Tk at the removal end C of the conveyor belt. The containers are then guided back to the feed end B of the conveyor belt.

According to FIG. K , the bowl-shaped containers 51 comprise a housing 511 for receiving the bags 6 with the polymerizable contents. Furthermore, chain links 51 ^ and holding tables 512, 513 are provided, which are arranged on both sides of the bottoms of the housing 511. A transport chain l60 is provided, which consists of individual chain elements l6l. These chain elements l6l are connected to one another by chain pins I63 and sleeves l62. The chain pins I63 are also used to fasten the chain links

The holding tables 512, 513 of the bowl-shaped containers 51 rest on the upper edge of the chain 160 of the transport device 16. The bowl-shaped containers 51 are fastened to the transport chain 160 in the region 515 which is at the front in the direction of movement, so that they are moved in the direction of arrow A together with the transport chain 160. The containers 51 are therefore pulled forward by the transport chain II6 via the connecting elements 514. the

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Transport chain l60 is guided semicircularly around a drive gear 18 according to FIG. 3, which with a drive motor not shown is connected. At the other end, the transport chain is l6o semicircular guided around a retaining gear 18 ·. In addition, are Idle rollers 14 and 14 'under the transport chain l6o "intended to hold the same.

Here, too, there are one or more light sources 2 in the reaction area above the transport chain between the ^ Feed end B and the acceptance end C along the transport direction intended. Below the acceptance end C of the transport chain 160 is a funnel 7 ^ for receiving the Bag 6 filled with the polymeric material 73 is provided.

Otherwise, the reaction device is designed as described above. The reaction chain l6o is driven by the drive gear l8 and moves together with the shell-shaped Container 51 in the direction of arrow A. The reaction liquid In the bags 16, light rays from the radiation source 2 are used to bring about the polymerization irradiated. The reaction is usually completed P or prepared for a complete reaction sequence, when the bowl-shaped containers 51 reach the doffing end C of the conveyor belt without further exposure to light being necessary. When the cupped Container 51 reach the dispensing end C, they are inclined in the vertical direction so that they the bags eject with the polymers. Then they are turned down and moved in the direction of the holding gear 18, where they are brought back into the upright horizontal position. Then these containers are at the receiving end B for

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the inclusion of additional bags with polymerizable content ready.

Of course, it is also possible to arrange the transport device in such a way that the feed end B in the
Workshop for the reaction liquid is arranged and that the discharge end C in the workshop for the treatment of the
polymeric material is arranged, with a region of the tunnel 3 is located outside between the two workshops. This makes it possible when the weather conditions are favorable
to use natural sunlight as a light source for photopolymerization. This modification of the process according to the invention combines two advantages, namely the production of the polymer at the same time as its transport
between the two factories, eliminating the need for transport time and work. In addition, it is designed
the process is economically advantageous through the use of natural sunlight.

The transport of the bags with the reaction liquid
can be continuous or intermittent, and
either by machine or manually. The speed of transport of the bags can be selected in view of the specific requirements of the polymerization, such as, for example, light irradiation and other requirements.

In the embodiment of the present invention described above, the bags with the reaction liquid were moved by means of a conveyor belt. However, a single bag can also be used in a stationary manner and irradiated with light without it bypassing the light source
to move. In doing so, equally good results are achieved. In this case, the bag can be placed on a mat

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be arranged below an external light source and exposed to a sufficient amount of light so that the photopolymerization is carried out.

Example:

The following is the photopolymerization of methyl methacrylate are described by the method according to the invention and with the aid of the device according to the invention. in the The following is a compilation of the specific data for the reaction device and the composition of the Reaction liquid given:

(a) Reaction facility data

Length of the reaction zone '42 m

Length of the tunnel 40 m

Transport speed of the belt 20 cm / min

Distance between bottom of the

Fluorescent lamps and top

of the ribbon 20 cm

40 watt fluorescent lamp

Number, of fluorescent lamps in

a number towards the

Belt movement 32

in the direction of the bandwidth Γ4

Total number of fluorescent lamps 448

(b) Composition of the reaction liquid

Methyl methacrylate 2 mol / liter

Reaction starter (diacetyl) 1 χ ίο "" ³ mol / liter

Water-methanol mixture as solvent (water: methanol = 1: 3)

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20 liters of the monomer are filled into a large number of polyethylene bags, each 60 cm wide and 60 cm long and 0.03 mm thick. The polyethylene bags filled with the liquid are placed in the bowl-shaped containers 5 (FIGS. 1 and 2) which are made of stainless steel. Each of the containers is 4O cm long, 40 cm wide and 15 cm high and has polished inner surfaces. The polyethylene bags are sealed with the exception of one corner which is cut off and forms an injection port. The reaction liquid is filled in through this filling inlet while the bag is in the container 5. This filling inlet is then closed. The filling height of the monomer in the bag is about 14 cm.

Thereafter, the bag 6 loaded with the bowl-shaped Vessel 5 is in the task area B of the transport device 1 the conveyor belt 11 is set.

The temperature in the tunnel is kept at 35 ° C. The monomer is irradiated with ultraviolet rays by means of the fluorescent lamps 21 for about 3 hours. After this Time has ended the reaction and the bags have reached the removal end C of the conveyor belt. The polymer appears in the sachets as a moist white powder. Using this technique, the polymer can be added in an amount 100 kg per hour can be generated.

The bags with the polymer are then taken from the bowl-shaped container 5 and opened. The polymer obtained is washed with water in a centrifugal separator to recover the powdery polymer. The yield at

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Polymer is about 93 % and the molecular weight of the polymer is about 740,000. The polymer turns out to be polymethyl methacrylate.

During this procedure, the temperature in the Reaction liquid controlled by means of cooling air, so that the heat generated during the reaction and that by the Heat generated by light sources is dissipated quickly and the temperature is kept within predetermined limits. The cooling air is introduced into the tunnel 3 by means of the ventilation device 4. In the present case, the Cooling air from the air outlets 44 through spaces blown over the bags 5 between the rows of fluorescent lamps 21 on the ceiling 33 of the tunnel 3. The amount of Injected air is controlled by the flaps 43. If rapid cooling or strong cooling is required, cooling water can be poured onto the polyethylene bags in the bowl-like ones Containers 5 are sprayed or injected, including pipes 35 for the cooling water.

The course of the reaction is so simple that it is not necessary to stir the reaction liquid, furthermore it is not necessary to constantly ™ clean the outside of the lamps in order to remove adhering polymer, as the Reaction liquid inside the transparent bag 6 is held and the light comes from an external light source 2. In addition, the reaction approaches of Protected access to air, since the bags 6 are tightly closed during the photopolymerization reaction and a Ingress of oxygen from the atmosphere is impossible. The polymer produced can easily be removed from the containers 5 and fed to the preparation process

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will. The polymer produced is namely in the bags 6 and can be transported further in this form will. The layer thickness of the reaction medium is sufficiently thin so that the light rays are easy and complete can enforce the entire reaction liquid, thereby providing excellent uniformity in the quality of the polymer produced.

By using the assembly line system, the process can be designed continuously and if the full capacity of the device according to the invention can the polymerization can be done in mass production. Because the amount of the reaction liquid in each of the bags is relative If the heat of reaction generated is low, it is kept within relatively narrow limits and cannot build up. Therefore the reaction temperature can be easily controlled. Furthermore, the reaction has to be carried out in the form of relative small units of polymerizable material in the bags have the advantage of causing an erroneous reaction can be disposed of in a single bag with the least possible loss by removing that single bag can.

Since the light irradiation zone is formed as a tunnel, the inner surface of which has excellent light reflection the light from the light source can be used effectively. The tunnel construction also makes it easier to control the Reaction temperature and keeps contamination with dust and other contaminating materials to a minimum down. It is also used when using a conveyor belt system the tunnel for the most effective use of the light rays from the light sources and for effective control

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the reaction temperature. On the other hand, however, it is not absolutely necessary to use a tunnel, especially since the control of the reaction temperature is anyway
is pretty simple. In order to achieve the most efficient possible irradiation with light, the inner surfaces of the tunnel should be made of a material with good reflective properties, such as well-ground stainless steel or aluminum plates or mirror-coated or white-painted plates. The tunnel can be in any way
be constructed and can, for example, cover both the side areas fc and the top of the reaction zone. On the other hand, only the upper region of the reaction zone or only the side region thereof can be covered.

The method for photopolymerization comprises according to the invention the use of a transparent bag as a reaction container for receiving the reaction liquid and
irradiating this bag with the reaction liquid with light rays by means of an external light source to carry out photopolymerization and obtain a uniform excellent polymer.

In addition, a transport system, such as a
w conveyor belt are used according to the invention, which
can hold many bags of reaction liquid,
which are moved with the conveyor belt and irradiated sequentially or simultaneously with the light beams
will. This technique enables the photopolymerization to be carried out continuously in large quantities, which makes the process according to the invention suitable for industrial use
Mass production is suitable.

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Claims (12)

Claims (\ . A method for the production of a polymer by photopolymerization, characterized in that a reaction flow text with the polymer-exerable material is filled in a transparent bag, and is irradiated with an external light source, whereupon the polymer obtained is removed from the bag. 2. The method according to claim 1, characterized in that that the transparent bag is made of a polymeric material. 3. The method according to claim 2, characterized in that that the polymeric material is a polyolefin, preferably polyethylene or polypropylene or cellulose acetate. 4. The method according to any one of claims 1 to 3t characterized in that the polymerizable material consists of a monomer, a prepolymer or consists of a mixture of these. 5 «Method according to one of claims 1 to 4, characterized characterized in that the polymerizable material made of styrene, methyl methacrylate, acrylonitrile or Mixtures of the same. 109842/1845 6. The method according to any one of claims 1 to 5, characterized characterized in that the reaction liquid is a photosensitizer and / or a starter for the photopolymerization reaction contains. 7. The method according to any one of claims 1 to 6, characterized in that the reaction liquid a solvent for the polymerizable material and optionally for the starter and / or the sensitizer contains. 8. The method according to any one of claims 1 to 7 »thereby It is indicated that the bag is tightly closed before the irradiation. 9. The method according to any one of claims 1 to 8, characterized marked that visible light rays or ultraviolet light rays are used. 10. The method according to any one of claims 1 to 9, characterized in that bags filled with the reaction liquid with the polymerizable material are guided past the light source. 11. Device for performing the method according to claim 10, characterized by a transport device (1, l6), preferably a conveyor belt (11) or a conveyor chain (l6o) and arranged above Light sources (2). 109842 / 184B 2 Ί15706 12. The device according to claim 11, characterized by shell-shaped container (5 »5 ¹ ) for receiving the bag (6). 13 · Device according to one of claims 11 or 12, characterized in that the light sources (2) are arranged within a tunnel (3). l4. Device according to one of Claims 11 to 13 »characterized in that the intensity of the light sources (2) at one end of the transport device (1, 16) is larger than at the other end. 109842/184 5 Blank page