DE1199984B - Use of linear, saturated polyesters for the production of thin films - Google Patents

Description

Using linear, saturated polyesters to make thinner Films It is known that thin films are made from linear, saturated polyesters one or more aromatic dicarboxylic acids or their esters and a glycol tend to wrinkle and wrinkle.

Films that are less than about 0.00254cm thick may crease or even rolling them up will result in the foils at the fold or bend points tear.

In addition, rolls of such wrinkled films are difficult, if not not at all for making windings, e.g. B. for capacitors, usable. Experts have previously assumed that the addition of inorganic pigments to polyesters, the wrinkling in films made from the polyesters is increased.

It was therefore surprising to find that the wrinkle resistance of polyester films with a thickness of less than 0.00254 mm is then significantly improved can be, if one produces the films from polyesters, the only small amounts contain certain pigments. The addition of these pigments as fillers and / or as a matting agent for polyesters in larger quantities was already known.

The subject of the invention is the use of linear, saturated Polyesters containing 0.01 to 0.5 percent by weight of silica, titanium dioxide, zirconium oxide, Aluminum oxide, talc, gypsum, fluorspar, kaolin, mica, barium sulfate, calcium carbonate and / or bentonite with a refractive index of 1.4 to 1.8 and a particle size from 0.01 to 10 microns, for making films with one layer thickness less than 0.00254 cm.

Polyesters are particularly suitable for producing the films from a linear, high polymer condensation product of at least one aromatic Dicarboxylic acid with a glycol exist.

Suitable polyesters are, for example: polyethylene terephthalate, Polyester from terephthalic acid and 1,4-cyclohexanedimethanol, polyester from dimethyl terephthalate and 1, 4-cyclohexanedimethanol, polyesters made from terephthalic acid, succinic acid and 1,4-Cyclohexanedimethanol, polyester made from terephthalic acid, isophthalic acid and 1,4-cyclohexanedimethanol and polyesters made from 4,4'-sulfonyl-di-benzoic acid, succinic acid and 1,5-pentanediol.

The foils can be used in automatic without creasing or folding Packing devices are introduced.

Furthermore, the films can be processed into rolls or tubes, that do not stick to each other or stick to each other.

The pigments can be incorporated into the polyester by any known method incorporated, which enables the production of a uniform mixture of the poly- esters and the pigment. The pigments can be incorporated into the polyester e.g. B. by Mixing the ingredients in a device such as a Banbury mixer, a heating roller or a combination thereof. The pigments can are also incorporated into the polyesters during the polymerization dry mixing with the polymer with the polyester and by stirring in suitable dispersion media.

The fact that such small amounts of finely divided inorganic Pigments as enumerated above have such an effect on polyester exercise is also surprising because known pigments, such as Silicic acid when using yarns, rovings made of wool, rayon and the like for the purpose of Reduction in lubricity are added, an increase in the coefficient of friction cause. As already stated, the addition of a small amount of Silicic acid as well as the other specified pigments in polyesters the opposite Effect, d. H. the addition causes an increase in the sliding properties of the polyester.

Another surprising result is that the essentially colorless polyester cannot be changed by the pigments. Moreover, it causes the addition of the pigments has no adverse effects on the physical and electrical Properties of the foils.

In addition to the pigments, small amounts of other substances can be added to the polyesters Additives such as antioxidants, colorants and antistatic compounds. can be added.

The pigments added to the polyesters have refractive indices which are close to the refractive index of the polyester into which they are incorporated. The following table illustrates this fact. The table shows the refractive indices of pigments for films made of polyesters, e.g. B. from terephthalic acid, isophthalic acid, 1,4-cyclohexanedimethanol polyester in a ratio of 5: 1: 6 (refractive index 1.54 to 1.60) and polyethylene terephthalate (refractive index 1.64). Additive refractive index Fluorspar ............... 1.434 Silica gel ............... 1.46 Plaster of paris .................. 1.523 Silicic acid ............. 1,544 Aerosil ................ 1.55 Bentonite ............... 1.55 Kaolin ................. 1.561 to 1.567 Mica ............... 1.598 Talc ................ 1.589 Barium sulfate ........... 1.64 Calcium Carbonate ....... 1.657 Alumina ........ 1.760 to 1.768 The following examples are intended to illustrate the invention in more detail: Comparative Example The following comparative example shows the properties of two pigmented films of different thicknesses which were rolled up into a roll. Polyester films were used that contained less than 0.5 percent by weight of silica (SiO2) as pigment or were pigment-free. The following results were obtained: Appearance after rolling up Film thickness with SiO2 without SiO2 0.00762 cm well I acceptable 0.00127 cm well unusable The results show that a film with a thickness of less than 0.00254 cm without SiO2 content is unusable, while it can be used well by incorporating SiO2. In contrast, with a thicker film, the addition of SiO2 is less noticeable, ie the film can be processed both without SiO2 and with SiO2 content.

Example 1 To about 34 kg of a polyester which by condensation of terephthalic acid, isophthalic acid and 1,4-cyclohexanedimethanol in molar ratio of 5: 1: 6 and which contained an antioxidant became 27.2 g (about 0.08%) of finely divided silica having an average particle size of about 3 microns was added. The mixture was then vacuumed for about 40 hours dried at about 80 ° C. The polyester was then made using an extruder extruded into foils. the The film was exposed to a heat radiator in the Heat stretched lengthways by about 170 ovo, hot stretched widthwise at about 99 ° C by 1850 / o and fixed at 215 ° C. In this way, a roll of film about 120 m long was made obtained a thickness of about 0.00076 cm. The film became ribbons of one width from. about 3 cm blended and wound up, with a smooth, fold-free roll was obtained.

The same polyester that did not contain silica became the same Way dried, extruded, cross-stretched and heat-treated, thereby a 0.00076 cm thick film was obtained. This film was also made of about ~ 3 cm wide strips cut and wound, creating soft, wrinkled rolls were obtained.

To test the properties of the foils, capacitors were used thirty-five turns and a simple dielectric layer of both of the rolls specified above. Each slide was about 50.8 cm consumed. With regard to the mechanical properties of the capacitors and with regard to a leakage test carried out at 24 volts AC was found to that all of the twenty-five capacitors made using the polyester material - containing silica were acceptable during thirty-three Capacitors made from a non-silica polyester material only twelve were acceptable, these twelve being worse and jagged or had torn edges and folds.

Example 2 A polyester blend was made which was 0.04 Weight percent silica gel contained the reaction components in the example 1 were described, were added before their polymerization.

The polyester was extruded and hot drawn 200.0 °. It was an approximately 900 m long film with a thickness of approximately 0.0016 cm in the form of a smooth Receive a roll, which is then cut up and rewound into smooth, wrinkle-free rolls became. The same polyester containing no pigment was made in the same way extruded and hot drawn by 200%. Here about 840 m of a film of obtained about 0.0016 cm thick. These rolls were a little wrinkled, and when trying cutting and rewinding them proved impossible to rewind reels that weren't very wrinkled.

Example 3 A polyester was made from terephthalic acid and succinic acid and 1,4-cyclohexanedimethanol by condensation polymerization in molar proportions of 3: 1: 4, the 0.25 percent by weight TiO2 with an average particle size of 0.2 microns. The TiO2 was added before the polymerization. The polyester was extruded into a sheet about 1,350 m long and 0.00127 cm thick, which could be wound into a smooth, wrinkle-free roll.

Example 4 A polyester was made from 4,4'-sulfonyldibenzoic acid, Succinic acid and 1,5-pentanediol by condensation polymerization in molar proportions of 5: 1: 6, with the one to be polymerized mixture 0.08 percent by weight bentonite was added prior to polymerization. The polyester was extruded into a sheet with a thickness of 0.00127 cm and into a smooth, wrinkle-free roll with a length of about 270 m.

Claims (1)

Claim: Use of linear, saturated polyesters, the 0.01 to 0.5 weight percent silica, Titanium dioxide, zirconium oxide, aluminum oxide, Talc, gypsum, fluorspar, kaolin, mica, barium sulfate, calcium carbonate and / or Bentonite with a refractive index of 1.4 to 1.8 and a particle size of Contains 0.01 to 10 microns, for making single-layer films less than 0.00254 cm. Publications considered: Der Plastverarbeiter, May 1961, P. 205;