DE1704733A1 - Polyethylene terephthalate film and process for making the same - Google Patents

Description

PATENTANWXlTt

DR.-INQ. H. FINCKE DIPL. -INQ. H. BOHR DIPL.-INQ. S. STAEQER

Long distance call. '24 * 0 40

8 MUNICH β, MflllwMraB

15. NRZ. 1971

M 21283 - Dr.F / J? IGI Case P, 19402

P 17 04 735.5-16

description to the patent application of

IMPERIAL CHEMICAL INDUSTRIES LIIIITEI) ₁ . London,

"concerning:

"Polyethylene Terephthalate Film and Process for their production "

The priority of filing in the UK from 17, 6, 1966 i3t.

The invention relates to biaxially oriented film, in particular such film made of polyethylene terephthalate.

According to d6, «rn process for the production of biaxially oriented Polyethylene terephthalate film is the amorphous film after extrusion ^ »!], on a cold roller quenched a temperature that is below the glass transition temperature, so that crystallization of the extruded

109827/1574

th melt is avoided. Due to heat transfer limits a film that is more than 3.8 niia thick cannot easily getting produced. As the draw ratio for the production of uniformly oriented film from filled amorphous film is at least 3.25 J 1 in both the longitudinal and transverse directions, has the limitation the thickness of the amorphous film means that there is no uniformly oriented film with a thickness greater than about 0.36 mm is technically producible.

The aim of the invention is to overcome this difficulty.

According to the invention, a uniformly biaxially oriented polyethylene terephthalate film is created which a 1 to 15 # content of finely divided inert Has filler and a thickness of about 0.36 to about 0.09 mm.

According to the invention, a method for producing the film is proposed according to the invention, which consists in that an amorphous polyethylene terephthalate extruded with a 1- to 15 ^ sodium content of finely divided inert filler and then at 80 to 130 ⁰ C in the longitudinal - as well as the transverse direction, the draw ratio being so large that the film is drawn evenly, but is less than 3.25: 1.

The exact value of the draw ratio for even drawing of the film depends on that contained in the film Amount of the finely divided inert filler, the lower the draw ratio being possible, the more Filler is present. For example, a film with 1? & Filler cannot be pulled evenly, though the draw ratio is below 2.6: 1. Against this can a

109827/1574

BATH

0> ■ ".

Film with 5 i "filler at a draw ratio of 2.2 already: are pulled evenly. 1

A * film mesh with more than 15 % filler cannot easily be processed in an extruder.

The particle size of the fillers that can be used in the production of the films according to the invention, is 0.1 to 5 μ in advance. For some applications where the film is subject to heavy loads during molding it is also important that the distribution of particle sizes is within narrow limits. Examples of fillers are silica (including diatomaceous earth), silicates and aluminosilicates (β.B. clay and koalin), titanium dioxide, abrasives such as β.B. Glass or carborundum powder, and ornaments, such as talc and mica or mother-of-pearl flour are suitable.

In order to achieve the optimal dispersion of the filler in the films, the filler is preferably used during the Division of the polymer or its predecessors incorporated. He can s.B. easily added to the ethylene glycol before this is mixed with dimethyl terephthalate to prevent the ester exchange before the polymerization to achieve.

The amorphous polyethylene terephthalate film can be produced in that the melt emerging from the extruder immediately quenched to a temperature below the glass transition temperature. This can be expedient achieve in that the film is guided around a cooled rotating drum. To the thick films according to the invention To produce successfully, it is necessary that the heat transfer «between the extruded film and the cooling drum is very good. Thus, the film is preferably pressed onto the drum, for example by a jet of cooled air

109827/1574

by means of an electrostatic charge on the top of the foil while holding the drum on a substantially voltage lower than the voltage on the electrostatic charging wire held near the top of the foil by preferably grounding the drum.

The films can be drawn in a manner known per se. They can be pulled lengthways first and then crossways or crossways first. For drawing in the longitudinal direction, the film can expediently be passed through slowly or rapidly rotating pairs of rollers, with an infrared heater, for example, being arranged between the two pairs of rollers. The ZicV.en in the Längurichtunt; but can be effected in that the film is guided over a series of heated rollers arranged at a small distance from one another, v / o all or some, for example the first and the last, are driven. The drawing of the film in the transverse direction can expediently be carried out with a drawing frame, _t that in a hot air oven. is held so that the drawing temperature can be maintained.

The pulling processes for the longitudinal and transverse directions can also be effected simultaneously instead of one after the other, for which several devices have been proposed, such as a pulling mechanism in which the frame rails diverge for pulling in the transverse direction, while the longitudinal distance between for simultaneous pulling in the longitudinal direction the clamps become larger and larger as they pass through the device. Preferably, the oriented films are heat set according to the invention, ie, they are wärhend gehindeTt at a shrinkage at a temperature in the range 150 to 23O ° C, preferably maintained at 180 to 230 ⁰ C. If the films according to the invention ^{are kept at 200 °} C. for 1 minute, they do not shrink by more than 3 % *

109827/1574

The pollen according to the invention can be modified in many ways in well-known catfish, for example provided with a coating consisting of a melt, a solution or a dispersion of a thermoplastic material in order to make it heat-sealable. Such coatings can consist of polyethylene, ethylene / vinyl acetate copolyraeren, polyvinyl acetate, hydrolyzed polyvinyl acetate, vinyl chloride / vinyl acetate copolymers, butadiene / methyl methacrylate copolymers or butadiene / methyl methacrylate / styrene copolymers. The heat sealable coatings can also be chosen such that they also comparable to the film a Undurchläßlgkeit against water vapor and other oasis M

Rent. Examples of this are coatings of copolymers of vinylidene chloride with one or more of the Compounds: acrylonitrile, itaconic acid, vinyl chloride and Mention acrylic acid. The foils can also be coated with other substances, such as B.B. Paper, wood, sheet metal or metal foil, be layered.

The films according to the invention have many possible uses because they have a good surface finish obtained without the use of costly coating processes and because they are easily deformed let, because a lower draw ratio is used in their manufacture finding for the production of facing panels, a.B. for household appliances or the construction of buildings and Vehicles, especially when a lower weight is required, such as aircraft. For this purpose, they give thermoplastic sheets of a previously unknown dimensional stability, so that they are easy can be assembled.

The foils can be further processed into porateiles, e.g. by vacuum forming in the usual vacuum forming

109827/157 *

BAB QWfiÖNAL

forming temperature or by mechanical deformation by means of punching or pressing machines, v ^; e they are used, for example, for the production of pressed parts from 31ech. Further examples of these latter processes are given in the applicant's British patent application 29 626/65. By means of such pressing processes, metal parts can also be firmly connected to the foils according to the invention. For example, metal hinges could be fitted in a flush manner, in order to be used, for example, for the production of kuchdeckein. Because of the dimensional stability of the thermoformed foils, they are particularly suitable for the production of molded parts by vacuum forming or cold pressing of molded parts that are heated during use, e.g. molded parts that are to be housed in the engine compartment of a motor vehicle or used as reflectors in lighting equipment or low-power radiant heaters.

Other uses for the films of the present invention include, for example, slot liners and closures for electric motors; Stiffening pads for clothing made of textiles, e.g. stiffening inserts for collars; Wrapping tapes; Rulers and protractors; Seals; Fracture plates; Membranes and conveyor belts.

example 1

A polyethylene terephthalate film with a thickness of 2.59 mm and a 1.8 # content of titanium dioxide was extruded and quenched on a grounded cooling drum, to which it is electrostatically pressed with the aid of an electrostatic charging wire. The average particle size of the titanium dioxide is 0.2 μ, and 90 i> of the particles are in the range 0.15 μ than 0.3. The film is first in the longitudinal direction at 85 ⁰ C uno

109827/1574

BATH

then in each case in the cross direction also at 85 ⁰ C under a draw ratio of 2.6: drawn. 1 The film is then heat-set in an extension of the transverse drawing frame at 21O ⁰ C. thereby preventing it from shrinking.

The resulting film has a thickness of 0.33 mm and an extremely glossy surface. When heated to 200 ⁰ C for 1 "linute the shrinkage of the film is 2?>.

A number of hemispherical bowls are made at room temperature pressed with a pressing machine from circular blanks which have been cut out of the film. Included a die with a diameter of 12.7 mm is used. Blanks with a diameter of up to about 30.5 mm are made of perfect shape, which do not have any cracks. or have crazing or splitting.

Example 2

An undrawn polyethylene terephthalate film having a thickness of 2.59 mm and a 10 $ sodium content in the titanium dioxide according to Example 1 as the filler is initially in the longitudinal direction and then in the transverse direction, respectively at 80 to 85 ⁰ C under a draw ratio of 2.4 : 1 drawn and then heat-set while maintaining the surface area at 210 ⁰ C.

The resulting film has a thickness of 0.457 mm. When the film is heated to 200 ^° C. for 1 minute, the shrinkage is 2 f>.

Patent claims:

109827/1574

Claims (4)

Patent application c 1. Uniformly "biaxially oriented polyethylene terephthalate with a 1 to 15% content of finely divided inert filler, characterized in that it is in the form of a sheet with a thickness of 0.36 to 0.89 mm. 2. Film according to claim 1, characterized in that the particle size of the filler is in the range 0.1 to 0.5 lies. 3. Foil according to claim 1 or 2, characterized in that it ^{experiences when heated to 200 0} C for fung of not more than £ 3>. that they shrink when heated to 200 ⁰ C for 1 minute 4. A method for producing a film according to any one of claims 1 to 3, characterized in that a amorphous polyethylene terephthalate film with a 1- to 15 ^ -igen content of finely divided inert filler extruded and then drawn at 80 to 130 ° C in both the longitudinal and transverse directions, the drawing ratio is so large in each case that the film is pulled evenly, but is less than 3 »25: 1. PAT :: -! - 'A "WÄ! .T5 WMNG.H.FI OC. DIPL-INO. H EOHR DlPC-ING S. STAEGEi 109827/1574