DE742364C - Process for improving the mechanical properties of films or the like made from thermoformable polymerisation products - Google Patents

Description

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ISSUED ON DECEMBER 3, 1943

It is known that thermoformable organic, film-forming substances by pressing, Rolling. Or spraying in the heat in moldings and that the mechanical properties of these fittings very much depend on the processing temperature are dependent, and in general, the better, the higher the processing temperature lay. When improving the mechanical properties, however, higher temperatures are used with regard to the application limited, because from certain temperatures upwards the substances, for example stick to the apparatus or it has now been found that the mechanical properties of foils, Sheets, rods or threads of thermoformable polymerisation products, which in the absence of volatile solvents, e.g. B. by pressing, rolling or spraying, can be improved significantly if you do this without pressure and friction heated to temperatures at which they only have low dimensional stability.

Polymerization products that can be thermoformed are those of vinyl chloride, styrene, Acrylic or methacrylonitrile or the methacrylic acid ester or polymerisation

of mixtures of these

bonds with one another or with others polymerizable under the same conditions Compounds and their conversion products, in particular chlorination products, called. In the usual way, the substances can also contain small amounts of plasticizers or lubricants Contain fillers or dyes.

The mechanical properties of the polymerization products mentioned change very strongly when heated. In particular, the elastic and plastic elongation of the fabrics changes. The values for elastic elongation initially increase when heated, but then drop significantly from a certain temperature. The plastic expansion is significantly lower than the elastic at lower temperatures, while only plastic expansion is present at very high temperatures. ie when stretching, the molecules slide past each other and when cooling down they remain in the state brought about by the stretching. At the temperatures at which the films or the like are to be post-treated by the method according to the invention, the polymerization products have a number of special properties. The elastic stretch is practically no longer present at all. The tear resistance is also only extremely low. It is only a small fraction, e.g. B. with polyvinyl chloride a thousandth and less, the tear strength at normal temperature. As a result, the masses have little dimensional stability and are in a flowable state, so to speak. This post-treatment temperature is z. B. for polyvinyl chloride depending on the polymerization stage at 250 to 280 ² C. It can easily be determined for each polymerization product.

The heat treatment according to the invention only needs to take a very short time. The foils or the like can be placed over hot surfaces, for example standing or rotating cylinders, or being guided through hot zones. There can also be several such hot surfaces or hot Zones can be arranged one behind the other. When treating threads, one uses appropriately hot surfaces that have grooves. By using relatively short hot surfaces avoid the risk of the polymerization products in the stick to it at high temperatures, deform or even decompose. The painting for example with talc ock-r wax. The hot zones can also by radiating surfaces, on which the polymerization products in g Distance to be led along, to be formed. You can also get hot GaM ' against the polymerization products or let them flow through hot, indifferent ones Draw liquids. _

Also on objects lined with the named polymerization products or coated, the heat treatment can be carried out. So you can z. B. a wire wound with a film obtained by rolling for a short time heat the required temperature. With this treatment, shrinkage subsides the foil tightly to the wire. By pressing foils that have already been treated by the process according to the invention, thicker laminates or moldings can be used produce.

While the films produced in the absence of volatile solvents o.dgi. mostly show a more or less strong shrinkage on heating, the products treated according to the process according to the invention practically no longer shrink when heated again. Learn through the treatment, an improvement of the structure in terms of both surfaces and in terms dvc transparency and often an increase ⁹ ^ elongation at break at ordinary temperature and in almost all cases an increase in their elastic elongation at elevated temperature.

So shows z. B. a film made of hochpoiymerem vinyl chloride, which was obtained by rolling 1 <-. 'I 185 ⁰ C, where a rough and wrinkled or a decomposition of the product by the rolling process is avoided, at normal! "Temperature an expansion of only about JO ⁰ / ,,. rope) St for very long rolling time bd 185 ° C, the strain only about 4 "") are gesteigeit. the Folia begins i'ber already due to decomposition comparable no color. briefly treating a boi 185 ⁵ C obtained roll film of polyvinyl chloride at about j8o · (. 'where no discoloration occurs, the elongation of the film at ordinary ¹¹ S Licher temperature is, surprisingly, to 2oo ° / ₀ and by even more increased The I ¹ OHe then also shows a glossier surface and clearer transparency and hardly shrinks any more

more suitable, ζ. B. for cable wraps or sheaths, as dielectric Interlayers for capacitors or as packaging material.

From the following table are the values of the mechanical properties of such Foils made of poryvinyl chloride, unfilled and filled, can be seen.

Fillers no lot Mechanical up to 60 strain
in O/ 9 4O properties measured Soot j before treatment to 44 . ¹ ^ / 20th Aluminum; in the rolling direction to 43 ! ίο to l8 after treatment strain
in Q / No. Type j powder ' '14 to in the direction of travel ^111/0 I. Cadmium red j I. to 37 ; 7 to 7th the slide f. 200 to 300 i Titanium white ι
ι 3 measured to 42 29 Tear force
in grams 125 to 170 j 6 to per 100 deniers 150 to 185 I. 17th Tear force
in grams 7 to
I. 38 to 50 2 ■ 10 per 100 deniers 39 to 50 100 to 115 3 50 38 to 46 92 to 102 41 4th 42 34 to 38 5 33 to 46 36 38

When a copolymer of 80 parts vinyl chloride and 20 parts of styrene, which was verwalzt at 153 ⁰ C to form a film can the elastic elongation can be increased by a post-treatment on a hot surface at about 250 ⁰ C to three times the amount of the original elongation.

If the post-treatment of threads or ribbons takes place with simultaneous twisting, in this way, thicker, horsehair-like threads, threads and cords can be produced. To the Achieving a uniform twist is expediently carried over the tapes or threads short hot surfaces, especially over smooth or grooved cylinders or through funnels.

After this treatment, the films or the like can undergo a normal stretching at lower Temperatures at which the elastic elongation is still great. be subjected. The foils can also be stretched by guiding them over heated surfaces or through hot zones, but under strong tension.

The stretching can take place simultaneously or in succession in the longitudinal and transverse directions. The stretching of ribbons, threads and the like can also be carried out in a manner similar to that of heat treatment be made with simultaneous twisting.

It is advisable to choose the temperature for the subsequent stretching treatment.

_ Area in which the polymerisation products have their highest elastic elongation, e.g. B. for polyvinyl chloride 100 to 140 ⁰ C. This stretching treatment is a partial

κ- cniir o-rr »Ri> Krhöhnnp · Her tear resistance

treated at 280 ⁰ C polyvinyl chloride sheet to nine times the iirsprünglichen length which Röntgenbikl shows a clear fiber chart, the extremely high tensile strength from 280 to 330 g per 100 deniers has by drawing over a heated at 120 ⁰ C cylinder a film and easy to can split fine fibers. Without the previous heat treatment at 280 ^° C., the rolled film can only be stretched by about 70% ^{at 120 ° C.} It then only has a tear strength increased by about 20%, about ^only 55 § P ^{ro IO} ° deniers.

The invention does not cover the stretching of films or the like from polymerization products coveted or granted patent protection as such, but only for stretching the foils or the like, if they were previously heated according to the method according to the invention.

The patent 689 539 already relates to a method for stretching films or Ribbons made of organic, thermoformable plastics in the heat to multiples the original length, - at which one of volatile solvents practically free foils or tapes made from these masses, e.g. also foils obtained by rolling or Tapes, without applying pressure, pulls them over one or more heated surfaces in such a way that the foils are placed on the heated surface Area or immediately behind it. In contrast, the plates, Films, rods or threads according to the invention for a short "time to temperatures, in which they only have low dimensional stability

d. H. practically only such a pull should be exerted around the plates, foils or the like. To keep them tense and to prevent them from throwing themselves.

Table 2 below gives the values for tear strength, elongation at break and cleavage of polyvinyl chloride films, which differ at different temperatures were strongly stretched in comparison to films which were subjected to heat treatment 290 ° C and then stretched to 'IViI in the same way.

IS One at 185 ⁰ C 30th Cast foils temperature Stretching in% by
guided Tear resistance fracture Cleavable By 10 ", rolled foil 40 from a di- the the original C. in grams speed view treatment without oxane solution Elongation
in ⁰ C Length ' O 100 deniers each strain f S. the slide 20 treatment a 70 after the stretch
kung according to c e no cloudy by rolling
at iS5 ^c .C With aftertreatment 20th biggest possible
achievable d 10 to 20 (40 _ _ treatment at 290 ⁰ C 35 120 b 45 4 to 20 20. (40) , O 55 I70 7 ° 250 no brighter 20th 400 200 - milky II5 40 150 40 IS - - 200 450 185 8th - bright II9 400 ■ 830 220 45 small amount - 880 130 16 very good - 880 350 225 ir until 15 - milky 480 280 to 330 S. veine bright I30 650 170 18th small amount - 200 220 16 very good - 650 4OO 270 IO ceine - 150 I30 212 25th - - 260
- 170 12th - - I70 400 7OO 185 60 - - 820 105 30th Well bright II8 300 120 12th very good 150 II 820 220

For comparison, the table also shows the properties of a cast from Diocan Foil made of poly-dichloride specified.

The table clearly shows that the "treated at 290 ⁰ C and stretched at 119 ° C, the cast film surpasses 50 film in the mechanical properties to some extent, while the non-treated at the high temperatures films exhibit relatively low values in the mechanical properties It can also be clearly seen that, depending on the degree of subsequent stretching and the temperature at which stretching was carried out, the tear strength and elongation of the films are largely influenced and

Even when a film of the aforementioned copolymer of example, parts of vinyl chloride and 20 parts of styrene, which has been treated at 255 "C, may be obtained by a subsequent stretching at 9O ⁰ C by 150% the no tensile force of 40 g to 145 g per 1,000 Dtimers increase.

The films or threads that are still stretched after the heat treatment can also find versatile use. 1-z. B. in the cable industry, as a replacement for * Bast, used to make yarn. Ropes, horsehair, braids or fishing nets and for. Clothing, upholstery and decoration. The division of the highly oriented 120

these are woven into fabrics, in particular because of their chemical resistance can be used in many ways.

Claims (1)

Claim: Method of improving the mechanical properties of in the absence of volatile solvents by pressing, rolling or spraying made foils or the like from thermoformable Polymerization products, characterized in that the films or the like are heated to temperatures for a short time without pressure and stretching are heated, in which they have only low dimensional stability.