DE2247645A1 - ARTICLE IN FLEXIBLE, HEAT-TREATED, BIAXIAL ORIENTED FILM MADE OF POLYMERIC POLYESTER AND THE METHOD FOR ITS MANUFACTURING - Google Patents

Description

PATENT ADVOCATE

DtPL-iNo. - * <> i

HELMUI r-.ORTZ ψ, / V

6 Frankfurt em Main 70.

received

P 22 47 645.5 January 17, 1973

Gze / Ra.

Union Carbide Corporation, New York, N.Y. 10017 / U.S.A.

Article made from flexible, heat-treated, biaxially oriented film made from polymeric polyester and process for its Manufacturing

The present invention relates to articles made from flexible, heat treated, biaxially oriented polymeric file Polyesters and a process for their manufacture; in particular, the invention relates to an improved method of fusing films of polymeric polyester under the action of heat received with the item for packaging purposes.

Films made from polyester are well known; the characteristics of this. Materials have opened up a wide range of uses for it. Thanks to their high strength and transparency turn out to be such films are extremely valuable packaging materials of food and other products, but the use of these films has been limited by certain difficulties to this day, arising from heat fusing and bonding of the films together. Part of the difficulty in fusing polyester films arises from the fact that the FIlMe to obtain the required physical properties of a certain orientation operation are exposed, and those that occur when fusing under the action of heat

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Temperatures influence the oriented films, the strength of the molten parts being influenced both directly and in the aged state Polyester films for packaging purposes are mainly used as a base material for laminated or coated sheet materials, with polyolefins or other sub Thermally fusible coating materials that were applied to the polyester film in order to ensure the fusibility under the action of heat.

The object of the present invention is polyester films with increased tensile strength, which are suitable for packaging purposes.

Another object of the present invention relates to fused polyester films that have high tensile strength exhibit.

Yet another object of the present invention is to provide a method for fusing polyester filaments to provide under the action of heat, wherein the polyester films have high tensile strength and are suitable for packaging purposes.

The present invention results in a flexible, heat- treated, biaxially oriented polymeric article Polyester film; the invention also provides a method of making such articles.

The solution according to the invention is characterized by a Object made of polyester film, with a tensile strength of

ο films of at least about 1,000 kg / cm, the

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Film for the ratio of tensile strengths perpendicular to the and in the machining direction a value between around 0.67 and 1.5, and at least part of the Object has a bead-like fusion.

The present invention is based on the discovery that high strength flexible film articles are obtained when Films made of high-strength, polymeric * polyester under the influence of heat to be merged; In detail, the process consists of the following stages:

a) laying a first layer of flexible biaxially oriented, heat-treated film of polymeric polyester on a second layer on a film of like polymeric polyester, each of the layers of the film being characterized as having a tensile strength of at least about 1,000 kg / em has, and where for the ratio the tensile strength? possibilities perpendicular to and in the machining direction a value between approximately 0.67 and 1.5 is obtained;

b) Clamping the layers of film on top of one another near the su fusing portion, the first and second film layers, respectively be pressed firmly against each other, so that the jsu fusing portion of the film is held in a largely stress-free state · ;.

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c) Effect of heat on the stacked Layers of film from a heat source, with sufficient intensity and for sufficient duration, to keep the fusing superimposed portions of the stress relieved film into a bead-like fusion; and

d) keeping the layers of film pressed together until the heat source has been removed.

An essential aspect of the present invention is that the polyester film used has been biaxially oriented and then heat-treated so that it exhibits little shrinkage at elevated temperatures. Films which have less than approximately 3% ^{shrinkage at 150 ° C. and less than approximately 10% shrinkage at 200 °} C. can be used within the scope of the present invention. Heat treatment is understood to mean a process in which the oriented polyester film is treated with heat while the film is simultaneously under tension, which is usually carried out immediately after the process for orienting the film, as described, for example, in US Pat. No. 2,823,421 is.

Another essential aspect of the present The invention also resides in that the biaxially oriented, heat-treated polyester film has a tensile strength of at least about 1,000 kg / cm and preferably at least

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ο
1,250 kg / cm, and that the tensile strengths of each individual film layer, measured perpendicular to the machine direction (TD) and in the machine direction (MD), have a ratio of TD to MD of approximately 0.67 to 1.5 and preferably from approximately 0.85 to 1.3 to v /iron.

The first and second film layers can be separated from one another Sources related and one overlaid differently, furthermore a web of film can be folded lengthways and part of the web can be placed on top of the other part, the two layers can also be made from the top and bottom the lower layer of a film which is obtained in the form of a tube.

Means for clamping the layers of film, like them for example in the. U.S. Patent 3,243,330 can be used to stack the layers of film on top of one another to press and the part of the film to be fused in a largely stress-free state keep. The layers of film that are pressed together should be that part of the superimposed film form which is immediately adjacent to the part of the film or tape to be fused. That part of the tape or film j to be merged, and therefore is kept in a largely tension-free state, preferably consists of an approximately 3.2 to 6.4 mm wide band which extends generally over the entire width or length of; überoinnnderlegerton film, which merged is to be extended. The portion of the film

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which is pressed onto one another with the clamping devices can vary depending on the clamping devices used and is not important for the practice of the present invention, however it is essential that the film is pressed together over the entire length, this length being the same as the length of the film, which is melted and fused under the action of heat. Furthermore, the superposed film layers must be held under the clamping pressure until the film layers have melted and fused under the action of heat and until the heat source has been removed therefrom. According to a preferred embodiment, the film layers are pressed against one another until the melted layers have cooled below the melting point of the film.

Films made of polymeric polyester suitable for making articles according to the present invention consist of biaxially oriented film, linear polymeric esters, such as polyethylene terephthalate, which is described in US Pat. No. 2,465,319. Films with an average molecular weight of »umludest 15,000, with an intrinsic viscosity. of at least 0.5, and with a characteristic density of Kuinimlest about 1.39 gr / cra ", with a melting point between about 240 and 260 'C, with a tensile strength of at least about 1000 kg / cra, with a ratio of tensile strengths soiikroclit kui- ( Ti)) and in the Ufiui'beitungsrichtung (MD) of about 0-07 to 1.5, and c-INCRA shrinkage at elevated temperatures, at 150 ⁰ C under about 3%, and at:> 00 ° C below about 10% lies, are

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for the present invention. Films that are used with preference and have proven to be extremely advantageous are due to a tensile strength of at least about 1,250 kg / cm ² , a TD / MD ratio for the tensile strengths of about 0.85 to 1.3 and a shrinkage at elevated temperatures , which is below approximately 2% at 150 ° C. and below approximately 6% ^{at 200 ° C., characterized.}

The merging of the clamped together, superimposed and pressed together layers of polyester film with the properties listed above can be used in the Be carried out so that the stress-free part of the film is sufficiently heated for a sufficient time, to melt, the layers of the film melting together without excessive thermal degradation. It was recognized that while the temperature for fusing the layers of polyester film is not important and in a broad sense The range of suitable fusing temperatures can vary greatly, depending on the type of source used is probably of importance to the Scbraelzstellon for the Achieve the desired quality and uniformity * For example in the context of the present invention, those are preferred for fusing polyester films Heat emitters are used as described in US Pat. No. 3,243,330 are written. Such varia radiators can be used to fuse be used which have sufficient heat dissipation energy develop so that the material softens so that the film layers form a bead-like fusion melt together without the heat radiators touching the film or, alternatively, such devices can used as a heat radiator for fusing v / erdon, which

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Join the film layers in contact and be separated from it again, while they emit sufficient heat energy to the film softens and Zusammeiiiichaiitliyt, _f The heaters can in any arbitrary * | are heated © mperatür, is that high enough for the ^ iXm softens and melts together, but it is preferred to use heat lamps at temperatures of at least about 600 ⁰ C, and more preferably at temperatures between about 650 and 700 ⁰ C. The duration of action necessary for this temperature is very short, uni Fusions of uniform quality and tensile strength are easily obtained. . _;

Another notable advantage of the process of merging according to the present invention results from the manufacture of parallel and separate bead-like Fusions in the slack part of the film between the small devices that are being used to press the film layers together, and the film during the formation of the bead-like joints sswischen these Klemiaeinrichtungen is separated * Accordingly using a continuous web of superimposed layers of polyester film in the processes according to the invention separate ^ adjacent ^ fused Film segments produced at the same time.

Accordingly, when carrying out the invention Process a flexible ^ heat-treated ^ biaxial oricmtiertor Obtained an article made of a polyester film that is at least in Ginom part has a bulge-like fusion.

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Polyester films are available in thicknesses from about 0.005 mm to about 0.25 mm or even thicker, but flexible films between about 0.01 mm to 0.05 mm in thickness are generally preferred. A polyester film article having a part fused according to the present invention; exhibits an average strength of at least about 1 kg / cm of film width for the fusion and preferably a strength of at least about 1.4 kg / crt of film width when tested within 24 hours of manufacture, after aging for five weeks at 60 ^° C. average strengths of at least approximately 0.7 kg / cm resulted for the film width. The remarkable retention of strength for the fusion according to the invention after aging is of very great importance for the production of articles from polyester filmeiij and is one of the various advantages achieved by the present invention,

The flexible film articles according to the invention can in the form of tubes, bags, containers; Sacks and be brought into similar forms, which are common to numerous Suitable for packaging purposes and other types of application are. Such objects can be produced by fusing the film layers either in the processing direction or vertically can be prepared for this purpose, and also the desired Number of bead-like closures on iron.

The; the following examples serve to describe the present Invention without restricting it in any way

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example 1

In this example, a discontinuous radiator, namely the model W 5222 from Weldotron, was used for fusing. The fusing device contained clamping devices for clamping the film, which had stationary lower clamping jaws and movable upper clamping jaws, whereby the film is clamped between these clamping jaws and a movable radiant heating element contacts the film to be fused and is separated from it again was maintained at a temperature between about 650 ⁰ C and 700 ⁰ C and was long enough so that in a single Arbeltsgang complete fusion of the film layers has been achieved.

In this example, 0.0125 mm thick films were made of polymeric! Polyester with the properties listed in Table 1 is used. Flat sheets of the film were laid one on top of the other with each film oriented in the machine direction and in the direction perpendicular thereto. The clamping devices were in one _; a distance of 4.76 mm and pressed the layers of film onto one another so that there was a band between the clamps! of tension-free film was created in order to apply the premeltings to it. The Varschaelzungen were mounted both in processing & vichtutigjWle in the direction perpendicular thereto, wherein the merging in the vertical direction perpendicular% n of Bearbeitungsrichtuni; of the Fllcia

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was attached, and the fusion was placed in the working direction parallel to the machine direction of the film,

Table I.

Properties of the films property

Movie A. Movie B. . 2,450 ο
kg / em 1,290 kg / cm ² 1,640 kg / cm ² 1,300 ο
kg / cm 1.5 1.0 1.39 g / cm 1 ^ 395 g / cm 1.8 % 2.0% 6.0% 0.55

Absolute strength perpendicular to the machining direction (TD)

Absolute strength

in the machining direction (MD) ratio TD / MD
Specific weight Shrinkage at 150 ^° C. Shrinkage at 200 ^° C. Intrinsic viscosity

The layers of film were melted and separated from the device with each pass of the fusing device, resulting in bead-like fusions along the edges of each adjacent segment of the fused film. The fused under heat Filmsogemente were examined within 24 hours after preparation, further samples were aged at 23 ° C and 60 ⁰ C for various times. A list of "the strength properties for the fusions ^ so / ohl with aged clay as with non-aged film samples" with fusions provides the following table II,

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strength Table II (kg / cm) B. F. of the mergers F i 1 ra at 60 ⁰ C
aged at 23 ° C
aged i 1 m A at 23 ° C
aged TD / MD Duration of
Aging TD / MD at 60 ⁰ C
aged TD / MD 1.37 / 1.88 (Weeks) 1.32 / 1.93 TD / MD 1.37 / 1.68 1.30 / 1.23 no
Aging 1.16 / 2.08 1.32 / 1.93 1.43 / 1.41 1 - 1.11 / 1.82 1.53 / 1.52 2 1.32 / 2.08 - - - - 1.00 / 1.14 3 - 1.11 / 1.53 1.19 / 1.52 0.80 / 1.71 4th 0.71 / 2.14 - 1.11 / 1.19 0.71 / 1.52 6th 0.53 / 2.05 0.52 / 1.12 1.53 / 1.64 0.78 / 1.62 S. 0.84 / 1.44 3.93 / 1.02 1.44 / 1.52 10 3.57 / 0.84

The tests to determine the absolute tensile strength and the strength of the fusions were carried out in accordance with Test programs according to ASTM D 882-64T b & i a trimming speed for the clamping cycles of about 50 cei / rain. A strength testing device was also used for these determinations from Instron used. Such properties as tensile strength and strength of fusion, like them are specified in the description and in the claims, are to be considered under consideration of this test progranin,

Fusions formed under the action of heat in films of polymeric polyester according to the present invention have high strength properties for the fusion ~

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work up. The fusions in film B, which has a TD / MD ratio of 1.0, show a somewhat better retention of the strength properties for the fusion than the fusions in film A (TD / MD ratio of 1.5) on aging over a longer period of time at 60 ⁰ C.

Example 2

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In this example, a continuously operating, radiant heat-supplying fusing machine from the company Weldotron, Model W 2318, as also used, for example, in US Pat. No. 3,243,330. In this Example were the following films made of polymer! Polyester used:

Film Ai identical to film A from Example 1

Film B: 0.013 mm thick polyester film with the following absolute tensile strength properties:

TD - -2. 240 kg / cm * MD - 1, 750 kg / cm ² TD / jMD 28

The fusions formed in Film A and Film "B", untor Use of continuously working, radiant heat lying Veraehmelaapparatux, as described above,

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and was operated at a temperature between about 650 C and .820 ⁰ C, and with a spacing of the clamping jaws of about 6.3 mm, exhibited the following fusion strengths:

Film A: Fusion Strength TD 1.25-1.43 kg / cm MD 1.25-1.43 kg / cm

Film B: Strength of Fusion TD 1.07-1.25 kg / cm MD 1.43 kg / cm

Example 3

Using the procedures described in Example 1 and apparatus were the following films made of polymeric Fused polyester.

Film A - Heat treated, biaxially oriented film with an intriusic viscosity. of about 0.55., with TD tensile strengths of 2,100 kji '/ cm' ⁵ and MD tensile strengths of 1,400 k ^ / cirt ² . The vnAiD liability was 1.5. The fiIw was 0.019 Baa (0.75 mils) thick.

Movie B -

V / äriitobehoiidelter, biaxially oriented pole yusterfilm with a Intrinsie- viscometers Caet unfiefa.hr of 0.55, with a

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Movie C -

TD tensile strength of 1,540 kg / cm and

ο an MD tensile strength of 1,470 kg / cm,

with a TD / MD ratio of 1.Oj the thickness of this film was 0.023 mm (0.92 mils).

Shrinkable biaxially oriented polyester film having a shrinkage of about 30% at 100 ⁰ C.

Superimposed layers of each of films A, B, and C were fused under the action of heat. The original strength (measured within 24 hours after formation of the fusion) of the fusions formed was for films A and B:

Movie A -

Movie B -

Movie C -

MD 2.42 kg / cm TD 1.07 kg / cm

MD 2.85 kg / cm TD 3.03 kg / cm

No fusions could be formed in this film.

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Claims (13)

- 16 - Claims 1.) Article made of flexible, heat-treated, biaxially oriented film made of polymeric polyester, characterized by an article made of polyester film, with a tensile strength of the film of at least about 1,000kg / cm ', the film being for the ratio the tensile strengths perpendicular to and in the machining direction have a value between approximately 0.67 and 1.5, and at least part of the object has a bulge-like fusion on ~ shows. 2. The object of claim 1, characterized by a tube as the object. 3. The object of claim 1, characterized by a laterally welded bag as the object. 4. Article according to one of claims 1 to 3, dr.clurcl? characterized in that the object r v.ulfitartiiio amalgamations nuJtveist. 5. (.k! F _; nnstan; J after one of the Ansj,: uelio 1 to 4, characterized in that the VerlJü2t-nis the Zu ^ - iestigiieitor! Perpendicular to the u: ui in ficr liearbcitungs direction oinou V ^ vt between ivigtifahr 0.85 and has. - 17 - 309818/0690 BATH ORIGINAL 6. Object according to one of claims 1 to 5, characterized characterized in that the bead-like fusion has a strength of at least about 0.71 kg / cm of the film having. 7 * A method for the production of objects according to any one of claims 1 to 6, by superimposing flexible films made of polymers! Polyester and fusing of these superimposed layers by . a) Laying a first layer on top of each other made of flexible, biaxially oriented, heat-treated Film of polymer polyester on a second layer of this polyester film, each of the film layers having a film tensile strength of at least approximately 1,000 kg / cm, the film being the ratio of tensile strength ■ abilities perpendicular to and in. The processing «- direction has a value between approximately 0.67 and 1.5; b) Clamping together part of the superposed film layers, adjacent to the portion to be fused under the action of heat _t wherein the first u.ud Äwsdte the film layer, be gegeneinanclergepresst ,, and the svu vorselu.ielzem.Ui film member is held in a largely stress-free state; - 18 - 309818/06 9 0 BATH ORIGINAL c.) Effect of heat on the stacked Layers of film from a heat source of sufficient intensity for a sufficient period of time to be stress-free melting the superposed film into a bead-like fusion; and d) to keep the superimposed film layers pressed together until the thermal energy source is taken away. 8. The method according to claim 7, characterized in that that a radiant heater is used as the source of heat energy. 9. The method according to any one of claims 7 or 8, characterized characterized in that the heat source is the one to be fused Part of the film is touched and deformed again, 10. The method according to any one of claims 7 to U , characterized in that the Ubex'cinanderlace film layers have been melted to separate, adjacent, vulst-like fusions. 11. The method according to any one of claims 7 to 10, characterized characterized in that the film layers for the ratio of tensile strengths perpendicular to the unci in the Working direction has a value between approx 0> ö5 and 1.3. 12. The method according to any one of claims 7 to 11, characterized characterized in that the heat source is at least one Temperature of uniit-iähr GOO (J nui'wc. Is, - 13 ~ 3 0 9818/0690 BATH ORIGINAL 13. The method according to any one of claims 7 to 12, characterized in that the Yiärmequelle the the part of the film to be fused is touched and severed. - 309 8 18/0690 BATH ORIGINAL