JPS5849168B2 - Continuous plate making method using opposing belts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves continuously heating polymerizable raw materials to polymerize and harden them.
The present invention relates to an opposed belt type continuous plate manufacturing method for producing plate-shaped polymers.

An unsaturated monomer (hereinafter abbreviated as monomer) whose main component is a polymerizable raw material, particularly methyl methacrylate or methyl meccrylate.

) or partial polymers thereof (hereinafter abbreviated as syrup).

) is polymerized to form an infinitely long plate-shaped polymer (hereinafter abbreviated as plate).

) is a method for continuously manufacturing two endless belts (hereinafter abbreviated as belts) arranged so that opposing belt surfaces run in the same direction and at the same speed.

) and a continuous gasket running between the belt surfaces near both ends of the molding space, from one end of which a polymerizable raw material is supplied,
A method is known in which the belt is heated as it runs, polymerized and hardened, and the plate is taken out from the other end (for example, U.S. Pat. No. 2,500,728, U.S. Pat. No. 3,376).
, 371, 3,371, 383 and 3,872,197)
.

Generally, a heated polymerization zone is provided so that polymerization occurs as the belt runs.

This polymerization is normally carried out by heating both back surfaces of the upper and lower belts using a heating medium such as water, air, or infrared rays, and is carried out by heating the back surfaces of the upper and lower belts at a temperature of 100°C, which is the boiling point of the monomer.
A method is adopted in which the first polymerization zone is heated at a lower temperature and the second polymerization zone is heated to a temperature higher than 100°C to complete the polymerization, and then the plate is cooled and removed from the belt. ing.

However, in the above-mentioned plate making method, even if the opposing belt surfaces are smooth and the plate is made using a device that maintains the interval between the belt surfaces with high precision, and an optically good plate is obtained, When a plate is heated for the purpose of, for example, cutting into a shape, optical strain is newly developed due to the relaxation of strain within the plate, which impairs the appearance and has the drawback of causing a decrease in commercial value.

An object of the present invention is to provide an opposed-belt continuous plate manufacturing method for producing a plate-like product having excellent optical uniformity even after the obtained plate is subjected to heat softening treatment.

To provide an opposed belt type continuous plate making method that exhibits its true value especially when manufacturing thick plates.

The gist of the present invention is to provide gaskets that follow the running of the belts and are sandwiched between the opposing surfaces of two endless belts that run opposite each other at a certain interval, and near both ends of the two belts. A polymerizable raw material is continuously supplied from the upstream end into a molding space defined by This method is characterized in that the upper belt side is maintained at a higher temperature than the lower belt side in a zone where the flow rate progresses and the flow becomes impossible.

That is, as a specific example, this can be achieved by supplying the heating medium only to the back surface of the upper belt in the heating polymerization zone until the polymerization of the polymerizable raw material progresses to a state where it cannot flow.

Also, when supplying heating medium to the back surface of both the upper and lower belts, this can also be achieved by increasing the temperature of the heating medium supplied to the back surface of the upper belt compared to the back surface of the lower belt, or by increasing the amount of heating medium. It is.

The zone where the upper belt side is held at a higher temperature than the lower belt side is effective in the zone until the polymerizable raw material in the heating polymerization zone progresses to a state where it cannot flow, and even if it is carried out after that, the effect will not be maintained. Extremely small.

The temperature difference between the upper and lower belts varies depending on the polymerization temperature, the type and amount of initiator added, and when using syrup as a polymerizable raw material, the initial polymerization rate and viscosity, and the plate thickness, but it is large. It is more effective.

However, if the temperature of the lower belt surface is extremely low in this zone, the polymerization time will become longer, so in practice, the polymerization rate should be taken into consideration.

The temperature of the belt surface can be changed stepwise or continuously.

Any heating method may be used to heat the zone as long as it can carry out the present invention, but a method of spraying a heating medium such as hot water in the form of a shower has a large heat transfer coefficient and a high temperature. This is preferable because it is easy to control.

Hereinafter, the case where hot water is used for heating in this zone will be explained in more detail based on the drawings.

FIG. 1 shows the entire opposing belt type continuous plate making apparatus suitable for carrying out the present invention, in which the opposing endless bells N, 1' located above and below are connected to main pulleys 2, 3 and 2/,
3/ gives tension and is driven by the drive motor 16 to run in the same direction and at the same speed.

A pair of upper and lower rollers 4, 4' supports the belt 11' at a predetermined interval to regulate the thickness of the product.

Monomers or polymerizable raw materials mixed with catalysts and other auxiliaries are delivered to the bell N, 1' and the gaskets 7, 7' near both ends thereof using a metering pump 5 and an injection device 6 installed at the upstream end of the belt. It is supplied to a certain shaped space surrounded by.

The monomer or polymerizable raw material is supplied to hot water spray devices 8, 8.
The belt is heated by hot water sprayed onto the back surface 11, 11' of the belt, and further heated by far-infrared heaters 9, 9' to complete the polymerization.

Next, a cooling or warming zone 10. It is cooled or kept warm at 20 and continuously taken out as a plate-shaped product.

When supplying the monomer or syrup as a polymerizable raw material, any hot water temperature below 100°C can be used; however, in order to avoid increasing the size of the equipment and increase productivity, 60-9 in the sense of polymerization
A temperature of about 5°C is preferred.

2 and 3, hot water is used as the heating medium in the zone and is applied to the belts 1, 1 from the spray nozzles 81, 81'.
', shows the state in which hot water is sprayed on the back surface 11 and 11'.

In the conventional method, as shown in FIGS. 2 and 3, hot water was supplied by uniformly spraying the back surfaces 11 and 11' of both the upper and lower belts. The resulting plates had defects in optical properties after post-treatment such as heat softening.

In the same FIG. 2 and FIG. 3, the temperature of the hot water from the spray nozzle 81 that is sprayed on the upper belt back surface 11 is lower than that of the hot water from the spray nozzle 81' that is sprayed on the lower belt back surface 11'. Either increase the height or increase the amount of spray applied.

To change the spray amount, either change the spray pressure or use the spray nozzle 81' that sprays warm water onto the lower belt backrest 11'.
Reduce the pore diameter of

Furthermore, the number of spray nozzles 81' that spray warm water onto the back surface 11' of the lower belt is smaller than the number of spray nozzles 81 that spray warm water onto the back surface 11 of the upper belt.

The present invention is most easily accomplished with the apparatus shown in FIG.

That is, the polymerizable raw material supplied from the injection device 6 is transferred as the belt runs, and in this zone, the upper belt back surface 11
An embodiment is shown in which hot water is sprayed only from the spray nozzle 81 attached to the hot water piping 82, and hot water is not supplied to the back surface 11' of the lower belt.

Note that these hot water temperature and amount of hot water can also be changed as the polymerization progresses.

The polymerizable raw material used in the present invention is particularly methyl methacrylate or a monomer mixture containing methyl methacrylate as a main component and other unsaturated monomers, preferably methyl methacrylate 90 % by weight or more.

Other unsaturated monomers include monoethylenically unsaturated compounds and polyfunctional compounds that are copolymerizable with methyl methacrylate.

Examples of the monoethylenically unsaturated compound include Z-tacrylic esters, acrylic esters, and styrene.

Examples of the polyfunctional compound include methacrylic acid esters such as glycol dimethacrylate and allyl methacrylate, diallyl phthalate, and diethylene glycol bisallyl carbonate.

Furthermore, a mixture of these monomers and a suitable amount of polymer dissolved or suspended therein or a partially polymerized monomer/polymer mixture, that is, a syrup, can be used as long as the polymerizable raw material does not lose its fluidity.

A polymerization catalyst is mixed with the polymerizable raw material.

Examples of polymerization catalysts include abbisisobutyronitrile,
Azobisdimethylvaleronitrile, azobiscyclohexanenitrile, penzoyl peroxide, lauroyl peroxide, acetyl peroxide, cabryl peroxide, 2,4 dichlorobenzoyl peroxide, isopropyl peroxydicarbonate, isobutyl peroxide, acetyl cyclo Free radical catalysts such as xylsulfonyl peroxide can be used.

It is also possible to use a combination of redox polymerization catalysts such as peroxides and amines.

Various additives such as stabilizers, plasticizers, polymerization regulators, fillers, dyes, pigments, etc. may be added to the polymerizable raw material to the extent that they do not inhibit polymerization.

If desired, a release agent may be added to the extent that it does not have a substantial negative effect on product quality.

Examples will be described below.

"%" in the examples means % by weight.

Examples 1-4, Comparative Examples 1-2 Methyl methacrylate syrup with a polymerization rate of 25% (viscosity approximately 1
Using a polymerizable raw material prepared by mixing 2 poise 200G) with azobisdimethylvaleronitrile 3001)Ifit as a polymerization initiator and dioctyl sulfosuccinate 15 bleaching as a release agent, a plate with a thickness of 4.5 mm and 6 mm was used. A polymer was produced.

The equipment used is similar to that shown in FIG.

Polished thickness 1. 5 7W7M, width 3000 mm stainless steel endless belts 1.1' are located above and below, each with a main pulley 2.3.2' with a diameter of 2100 mm.
, 3' are hydraulically tensioned at a tension of 10 kg/i4, and the belts 1, 1' are connected to the main pulleys 2, 3'. 3.
By driving 2' and 3', it is made to travel at a speed of 1.5 m/min.

The polymerizable raw material is supplied through the injection device 6 by a metering pump 5, and at the same time, hollow pipes made of polyvinyl chloride mixed with a considerable amount of plasticizer are used as gaskets 7, 7' to seal the vicinity of both ends of the belt, and the upper and lower belts 11' Insert it near both ends of the opposing sides.

The total length of the zone from supplying the polymerizable raw material to taking out the plate-shaped product is 100 m, and the first half is 66 m long, with a group of rollers 4 and 4' arranged at 400 mm intervals to regulate the distance between both sides of the belt. The first polymerization zone is heated by spraying hot water at 80℃, and the latter 34m is the second polymerization zone where the temperature is raised to 140℃ with a far-infrared heater 99' and the temperature is maintained, and the air blower. Cooling zone 1 by
0 20.

In the first polymerization zone, as shown in Figure 4, Examples 1, 2, 3, and 4 were prepared by varying the zone length in which hot water was sprayed only on the back surface 11 of the upper belt, and in Figure 3, the upper and lower belt Table 1 shows Comparative Examples 1 and 2 in which the plates were made by the conventional method of uniformly spraying hot water on both back surfaces 11 and 11'.

From these results, it was found that the Example was superior to the Comparative Example in that the degree of optical strain developed after the obtained plate was heat-treated was smaller.

Examples 5-7. Using the apparatus shown in FIGS. 2 and 3, in the zone from the upstream end of the first polymerization zone to door 15, the hot water spray amount ratio of the lower belt back surface 11' to the upper belt back surface 11 was set to 0.1,
Plate manufacturing was carried out under exactly the same conditions as in Example 1, except that the thicknesses were 0.3 and 0.6, and the plate thickness was 5 mm.

On the other hand, as Comparative Example 3, hot water was sprayed only on the lower belt side, and plate manufacturing was carried out under the same conditions.

The results are shown in Table-2.

From these results, the degree of optical distortion after heat treatment of the obtained plate was smaller in each Example than in Comparative Example 3,
It turned out to be excellent.

Examples 8 and 9, Comparative Example 4 For methyl methacrylate syrup with a polymerization rate of 25%, azobisdimethylvaleroni I-IJ Le 6oopp! Il
Using a polymerizable raw material mixed with 10 m of dioctyl sulfosuccinate and 10 m of dioctyl sulfosuccinate, the belt speed was set to 2.5 m/min, the plate thickness was set to 4, and the hot water spray in the first polymerization zone was applied to both back surfaces 11 of the upper and lower belts as shown in Figure 3. .11', and in a zone 9 m from the upstream end of the first polymerization zone, the temperature of the hot water sprayed onto the back surface 11 of the upper belt was 85°C, and the temperature of the hot water sprayed onto the back surface 11' of the lower belt was varied. The results are shown in Table 3.

It can be seen from Table 3 that Examples 8 and 9 are superior to Comparative Example 4.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of an opposed belt type continuous plate making apparatus used for carrying out the present invention. Fig. 2 is a longitudinal sectional side view of the zone as the polymerizable raw material in the heating polymerization zone progresses to polymerization until it becomes unable to flow, Fig. 3 is a longitudinal sectional front view thereof, and Fig. 4 is a longitudinal sectional front view showing another example. It is. 1, 1' are endless belts, 2, 2', 3.
3' is the main pool 'J-', 4.4' is a group of rollers, 5 is a metering pump, 6 is a polymerizable raw material injection device, 7, 7' is a gasket, 8, 8' is a hot water spray device, 9, 9' is the far infrared heater, 11.11' is the back of the upper and lower belts, 81, 81
' is a spray nozzle, and 12 is a plate-shaped polymer.

Claims (1)

[Scope of Claims] 1. A gasket formed by two endless belts running opposite each other at a certain interval and a gasket sandwiched between the opposite sides of the two belts and running following the belts. A polymerizable raw material is continuously supplied from the upstream end into a certain molding space, and as the belt runs, it is heated and polymerized and cured via the belt surface.The polymerization of the polymerizable raw material in the heated polymerization zone progresses and the flow occurs. An opposing belt type continuous plate making method characterized by maintaining the upper belt side at a higher temperature than the lower belt side in the range until the belt becomes impossible. 2. The continuous board making method according to claim 1, wherein the polymerizable raw material is an unsaturated monomer whose main component is methyl methacrylate or methyl meccrylate, or a partial polymer thereof. 3. The opposed-belt continuous plate manufacturing method according to claim 1 or 2, in which warm water is used as a heating medium in the heated polymerization zone where the polymerizable raw material progresses in polymerization until it reaches a non-flowable state. 4. A patent characterized in that the upper belt side is maintained at a higher temperature than the lower belt side by heating only the upper belt surface in the heated polymerization zone where the polymerizable raw material progresses to polymerization and reaches a state where it cannot flow. Claim 1,
The opposed belt type continuous plate making method according to item 2 or 3. 5. A patent claim characterized in that the amount of heating medium supplied to the upper belt surface side is larger than that to the lower belt surface side in the heating polymerization zone where the polymerizable raw material progresses to polymerization and reaches a state where it cannot flow. Range 1, 2 or 3
Continuous plate making method using opposed belts as described in . 6. A patent claim characterized in that the temperature of the heating medium supplied to the upper belt surface side is set higher than that of the lower belt surface side in the zone where the polymerizable raw material in the heating polymerization zone progresses to polymerization and reaches a state where it cannot flow. The opposed belt type continuous plate making method according to scope 1, 2 or 3.