KR820000576B1 - Process for the manufacture of oriented shhets of thermoplastic resin whicb are pretected against the action of ultraviolet rays - Google Patents

Abstract

The sheet is manufd. by extrusing a sheet from the the thermoplastic resin, conditioning this sheet to a temp. favoring orientation, stretching to induce mol. orientation tensions and cooling under tension to below T2. Before stret ching solvent exerting swelling action and 5-40 wt.% of>1 anti-UV agent which is soluble in the solvent. The amt. of soln. deposited per m2 of the surface of the sheet is 20-200 g. The solvent is evapd.<60 sec after appling the solvent to a mixt. of 1,1,2-trichloroethane and tetrachloroethylene and the anti-UV agent is benzophenone deriv.

Description

The manufacturing method of the orientation sheet which is a thermoplastic resin protected by ultraviolet action.

This invention relates to the manufacturing method of the orientation sheet which is a thermoplastic resin protected by ultraviolet action.

It can be seen that the physical properties of the thermoplastic resin sheet can be sufficiently improved by the alignment treatment.

The direct method of making the alignment sheet of the thermoplastic resin is to extrude a thick sheet from this resin, to adjust the sheet to a temperature suitable for stretching and orienting, and to stretch the adjusted sheet to at least one straight direction to induce an orientational tension, The sheet under tension is cooled to a temperature below the secondary transition temperature of the resin so that the induced tensile tension is fixed.

During or after stretching as described in French Patent Nos. 2,073,691, filed December 11, 1970 and 2,137,447, filed May 9, 1972, in the name of the applicant, for example, It is also possible to make a special sheet. In particular, these sheets are used for roof coverings and to cover building facades.

Moreover, ultraviolet light has a very detrimental effect on the physical properties of the thermoplastic site.

Therefore, it is necessary to protect the thermoplastic resin sites exposed to solar radiation against the action of solar radiation.

A method that can be used to achieve this protection is to mix a sunscreen agent such as a benzophenone derivative or a benzotriazole derivative in the composition used to prepare the sheet.

In fact, these sunscreens are uneconomical because they are difficult to synthesize, and only the sunscreens in the surface layer of the sheet have protection against the action of ultraviolet light. This approach improves the techniques applied to the sheets formed and in the surface layers of these sheets. This is possible by concentrating the sunscreen.

It has therefore been proposed to coat sheets with a protective varnish containing sunscreen, but this method has made some progress with special varnishes, but this is expensive to achieve the final protection of the protective layer.

It has also been proposed to immerse the sheet in a material which can dissolve the sunscreen and exhibit limited expansion in the resin surface layer. As a result, the sunscreen penetrates into the surface of the soft part of the sheet and remains dispersed therein after the solvent has evaporated. However, this latter method involves both surface treatment of unnecessary and unwanted sheets and makes it necessary to use large drying equipment.

Moreover, this method is actually relatively difficult and has many difficulties when dealing with continuous sheets.

Finally, it has been proposed to surface-coat at least one side of the sheet using a solution of the same type as used in the dipping method. This method is particularly economical and effective but cannot be used to treat the oriented sheets. Applicants have found that this method leads to the release of the induced tensile tension on the sheet surface portion, resulting in cracking, which is the starting point of the sheet rupture and causes the sheet to break.

This results in a substantial reduction in the physical properties required in the orientation and shrinkage of the sheet. In addition, in the case of non-planar alignment sheets such as corrugated sheets, the use of this method is difficult.

In the present invention, a method of protecting the alignment sheet, which is a thermoplastic resin, against the action of ultraviolet rays has been developed, which is particularly effective, economical and eliminates the drawbacks of the conventional method. Accordingly, the present invention relates to a method for producing an alignment sheet, which is a thermoplastic resin which is protected against UV action, which extrudes a sheet into a resin, adjusts the sheet to a temperature suitable for stretching and orientating the sheet, and adjusts the adjusted sheet to molecules in the sheet. Elongate at least one straight line to induce orientational tension and cool the elongated sheet to a temperature below the secondary transition temperature of the resin, wherein at least one solvent exhibits expansion in the resin before elongating the controlled sheet; A solution of at least one sunscreen that can be dissolved in a solvent is used on at least one side of the sheet and is prepared by evaporating the solvent.

It can be seen that even if the sheet is stretched after coating according to this process, there is no change in the prevention of ultraviolet rays given to the sheet, and in particular, since the thickness of the surface layer and the UV-protecting agent contained in the layer are sufficient, the sheet is effectively protected. Furthermore, stretching the sheet after coating does not cause any surface cracking and no other defects.

The amount of UV protection agent that penetrates the sheet in solution form depends on the elongation rate used during fabrication of the orientation sheet and the final amount to be distributed on the surface of the orientation sheet.

Per square meter of sheet surface treated prior to stretching, the amount of sunscreen penetrated during coating is preferably 10-30 g / m 2.

All of the sunscreens can be used, and in particular, it depends on the nature of the thermoplastic resin constituting the sheet and the simplicity of the conditions of use of the sheet. Some examples of sunscreens that can be used include benzophenone derivatives, such as hydroxyl derivatives and alkoxylated derivatives, benzotriazole derivatives, substituted acryronitrile and aryl esters.

However, the resin here is mainly polyvinyl chloride, and in the present invention, 2,2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-octoxy benzo Preferred are benzophenone derivatives such as phenone. Several other sunscreens can also be used.

Generally the amount of sunscreen present in the treatment solution is 5-40% by weight of the solution, preferably 10-30% by weight. In particular, it is selected according to the properties of the thermoplastic resin constituting the sheet and the amount of sunscreen to penetrate. Selection of the solvent used to prepare the solvent or coating solution is selected according to the following conditions.

(1) be able to dissolve the sunscreen used;

(2) Solvents should exhibit an swelling action on the surface of the resin to allow penetration of the sunscreen during treatment.

It is also essential that the solvent be as inexpensive as possible, not toxic in use, be fire resistant and not adversely affect the hardening resistance of the sheet. According to various good methods of this invention, the solvent which improves the hardening resistance of a sheet is selected.

The solvent of the solvent or treatment solution is selected according to the resinous function which constitutes the sheet and can be measured in each case by preliminary experiments.

Thus, when the sheet consists of a resin mainly composed of vinyl chloride, such as a copolymer containing at least 50% by weight of the amount derived from vinyl chloride or a homopolymer of vinyl chloride, as a solvent in the present invention, 1, such as methylene chloride and dichloroethane, Preference is given to using chlorinated solvents derived from hydrocarbons containing -3 carbon atoms.

The best results are obtained using a mixture of 1,1,2-trichloroethane and tetrachloroethylene with a weight ratio between 1.5 and 3, or with a solution containing 10-40 g of sunscreen per 100 g of solution. In this case, the amount of solution penetrated per square meter and per face of the sheet to be treated is preferably 20-200 g.

In order to facilitate dissolving the sunscreen in the solvent and infiltrating the solution into the surface layer of the treated surface of the sheet, it is preferable to use the solution at a temperature above normal temperature and below boiling point under standard pressure.

In addition, penetration of the solution is facilitated when the sheet is at a relatively high temperature or when the temperature of the secondary transition is higher than the general temperature.

In order to have sufficient time for the solution to penetrate to a sufficient extent, it is preferable to select a solvent or solvent mixture having a boiling point, preferably a temperature above the temperature of the sheet treated under standard pressure.

Take the boiling point of 1,1,2-trichloroethane and tetrachloroethylene (1,1,2-tricooloethane is 114 ° C and tetrachloroethylene is 121 ° C), and the mixture of these solvents The solution can be used to treat the sheet at a temperature of 90-115 °. In this temperature range, a sheet made of a resin led by polyvinyl chloride can be elongated to induce orientational tension. It is preferred to use the solution in a sheet at a temperature that facilitates orientation by stretching, which temperature can be achieved by first extruding the sheet by passing it through one or more cooling rolls.

However, treatment of sheets at temperatures below or above their orientation temperature is all excluded, which sheets have their orientation temperature after UV treatment or, in some cases, before stretching treatment.

The treatment solution is preferably coated and used on the drawings to be treated, which is not particularly problematic if the surface is flat and the viscosity of the solution is low. For this purpose one or two sets of nebulizers or other similar devices may be used.

Since the operation can be continued and effectively, the apparatus can be simply adjusted to continuously manufacture the alignment sheet. After infiltrating the treatment solution, the solvent is evaporated off. However, this evaporation can occur when the solution has sufficiently penetrated the surface layer of the treated surface of the sheet.

The time between operation and evaporation can vary widely the properties of the solvent, sunscreen, resin, and sheet temperature depending on the desired penetration depth. Usually this time is 60 seconds or less, preferably 10-40 seconds.

In order to evaporate, it is preferable to pass a sheet through the chamber which evaporates a solvent. Therefore, the solvent can be condensed and rarely recycled. If the solvent vapor is toxic, it may be possible to prevent leakage of the vapor or to inhale the vapor.

The yarn is preferably stretched and then maintained at the temperature selected for orientation. However, if the yarn is heated with a thermal composition apparatus that keeps the sheet at a temperature that is optimal for orientation, the yarn can be held at a different temperature from the temperature to be stretched. Evaporation conditions (temperature, pressure and duration) can easily be measured empirically in some cases.

When removing the solvent, if necessary, the sheet is placed in a thermostat and then in a single-axis or double-side stretching device, and the stretched sheet is returned to a temperature below the secondary transition temperature of the resin constituting the sheet under tension. If necessary, the sheet oriented by elongation may optionally be dug up using, for example, the methods described in French Patent No. 2,073,691 filed December 11, 1870 and 2,137,447 filed May 9, 1972 by Applicant. You can do it with pictographs.

In more detail, the method of the present invention is continuously extruded, the extruded sheet is passed through a heating regulating roller to reach an orientation temperature, and the coated sheet is continuously coated with an ultraviolet ray treatment solution, The sheet coated with the yarn, which is maintained at the orientation temperature of the treated sheet, is passed through to evaporate the solvent in the solution, and finally the sheet is passed through the stretching device to the alignment device.

As described above, various parameters can be changed when using the method of the present invention, which mainly affects the thickness of the surface layer of the surface of the sheet treated according to the method. Various methods can be used to obtain the desired thickness here and generally this thickness is greater than 30 microns and 60-150 microns is preferred. One of the most interesting is the protection against UV radiation of transparent, translucent or opaque double oriented wavy sheets, mainly polyvinyl chloride, which is widely used in construction. The method according to the invention can be used to produce sheets in this period as well as to produce any other article oriented by stretching, such as a film, plate, blowfill, net or strip. Thus, it can be seen that the sheet is generally any article which is very deep and has at least one plane before orientation by stretching.

The following examples illustrate, by way of example, the actual state of the method of the invention and do not limit the scope of the invention.

EXAMPLE

The polyvinyl chloride sheet was continuously extruded with an extruder equipped with a balancing die having a width of 82 cm and a temperature of 200-220 ° C., and then cooled by passing the extruded sheet through a continuous roller maintained at a temperature of 115 ° C. The sheet exiting the roll had a thickness of 4,45 mm and a surface temperature of 120 ° C., and the moving speed was 1.3 m / min.

A solution containing 30% 1,1,2-trichloroethane, 50% tetrachloroethyl and 20% 2-hydroxy-4-methoxy-benzophenone (percent by weight) was adjusted Used on the top of the sheet, the solution is permeated at a rate of 17.5 g / m 2 of the sheet surface.

The sheet is passed through a 2 meter long enclosure, which is 20-50 cm from the point of use. The chamber is equipped with a circulation fan and an extraction fan, and the temperature is maintained at 120 ° C. Solvent vapor is extracted from the chamber, condensed and recycled. The dried sheet is passed through the rolls of the lower tank to extend to the species, the speed of the roll is controlled to stretch the sheet to 100% species, and the stretch roll is maintained at 115 ° C. The periphery of the sheet elongated in this way is gripped by a picture installed on a transverse device that stretches the sheet 100% transversely.

Transverse stretching of sheets is carried out in a room kept at 105 ° C and sealed and ventilated.

Finally, when a double-stranded sheet gripped by transverse elongation creep is injected into the waveguide device as described in French Patent No. 2,137,447, it has a waveform shape of 1.2 waveforms with a final width of 1.097 meters and has a wave-shaped profile. Obtain a sheet of paper.

The thus obtained corrugated sheet has a long repulsive force of 1,800 kg · cm / cm 2 at 20 ° C., which does not change after 36 months of exposure to the action of solar radiation.

However, comparing untreated identical double oriented corrugated sheets initially has the same tensile repulsive force; After 36 months of exposure to solar radiation, the value drops to 720 kg.cm/cm 2.

Claims (1)

After extracting the sheet from the resin, the sheet is adjusted to a temperature suitable for stretching and orienting, the adjusted sheet is stretched at least in a straight direction to induce molecular orientation tension of the sheet, and the stretched sheet is below the secondary transition temperature of the resin. In preparing an alignment sheet made of a thermoplastic resin which is cooled by stretching to a temperature to protect against ultraviolet action, 5-40 which can be dissolved in at least one solvent and a solvent exhibiting an expansion action in the resin before stretching the controlled sheet. Manufacture of an orientation sheet made of thermoplastic resin, characterized in that a solution of at least one UV protective agent in weight% is prepared on at least one side of the sheet with an amount of solution penetrated per square meter of the sheet surface of 20-200 g. Way.