DE1629593A1 - Polyethylene terephthalate film - Google Patents

Description

Polyethylene terephthalate film

The present invention relates to a polyethylene terephthalate film and a method for their production.

The polyethylene films belonging to the known state of the art Tere phthalates, which are usually characterized by an intrinsic viscosity of about 0.55, have various Defects, mainly that when stretched in only one direction, they are not dimensionally stable, so they become but, in order to make them dimensionally stable, fixed by heat, the PiIm fibers, ie. it splits in general 0 * 2

The subject of the present invention is nßn © ine hitaefixierte, non-fibrous polyethylene terephthalate film, characterized by a predominantly uniaxial ^, molecular orientation due to hedges by at least four times, one istrinsicviscös ^ * ^ · xsm. © ipdiester 0.65, a tensile strength of at least 3

& ® and

a shrinkage which is not more in the stretching direction at 105 ⁰ C as 10 #, 50 #, and at least strength elongation in the direction transverse to the stretching direction.

In one of the various preferred embodiments the film according to the invention has a coating on at least one side, for example an adhesive composition, a composition containing magnetic particles or a metallic coating which adheres firmly to the surface.

Erfindungsgemäes one can produce such a film by, predominantly stretched, an amorphous film of polyethylene terephthalate having a Intrinsicviseosität of at least 0.65 in one direction and above 80 C heat-fixed _β Gemäß8 a preferred, continuous combined process for producing this film © xtrudiert one polyethylene terephthalate, which is Intrinsicviscosität ailndestens about 0.65, in sheet form at a temperature of 270 to 315 ° C \ extrudlerte scares the film to below 80 ⁰ C., to obtain the film in substantially amorphous form} heating the film to above 80 ° and 0 in a region in which orientation mofekulare erfolgtj the sheet expands in a direction at least four times in excess of 80 ⁰ C out; and heated the stretched film to 150 to 250 ⁰ C, while it is preferably held clamped- »

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The peculiarity and advantages of the film according to the invention are derived from the The following description and the various figures shown in the accompanying drawings can be better understood

Fig. 1 is a graphical representation of the relationship between

de »Tensile strength and the stretching ratio (degree of stretching) for unidirectional stretched polyethylene terephthalate film;

Fig. 2 is a graph showing the relationship between Heat-fixed operation and elongation at break in the transverse direction to the direction of the predominant orientation for unidirectional stretched polyethylene terephthalate film j

Fig. 3 is a graph showing the relationship between the Tension in the transverse direction to the prevailing orientation direction and the intrinsic viscosity for one direction stretched, heat-set polyethylene terephthalate film;

Fig. 4 is a graph showing the relationship between the pneumatic impact strengthened it and the intrinsic viscosity for heat-set polyethylene terephthalate film stretched in one direction o

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Fig. 1 tends that stretching greatly increases tensile strength in the stretching direction. The Ergebniese shown in Fig. 1 was obtained by conventional Polyäthylenterephthalatfolien ait a Intrineicviecosität of 0.55 at a temperature of 90 ⁰ C in a direction were gereokt, wherein the degree of stretching of a portion of the Heckverhältniese slightly large than once to about five times comprised su . The ones stretched in one direction. Nioht films were fixed in the Hitee, üie vorxeiinaixigxei * * the 1st Folienreokung leioht daraus'cu recognize that ungereokte film (Beckverhältnls 1) a tensile strength of less than kg / o ^«2 comprises, during a stretched on the quadruple · Foil" a Tensile strength of about 2800 kg / om possessed. The fact that a film stretched twice has a tensile strength modulus of 32,300 kg / om, while a film stretched five times has a modulus of approximately 126,000 kg / ee having.

Figure 1 also illustrates the practical limitation to one Reqkgrad «which can be used for conventional polyethylene terephthalate foils, if such a foil is more than approximately stretches five times in one direction, the film is Defibration unusable.

Berköaalicn ·, polyethylene films stretched in one direction « terephthalic, which are intact in their structure for their practical use, are limited to those films that are up to on Reckverbältniese below about S gertefct «« »den are.

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However, such films have no dimensional stability and must be fixed in the heat so that they become dimensionally stable, that is, so that they do not shrink by more than 10 -5 ^{at 105 ° C.} The heat setting, however, causes fraying in such films. .

FIG. 2 shows the disadvantageous effect of the heat setting temperature on the elongation at break in the transverse direction to the stretching direction of conventional polyethylene terephthalate films stretched in one direction and having an intrinsic viscosity of 0.55 »in which the elongation is up to 600 io . It can be seen from Fig. 2 that the elongation at break of such films decreases considerably as the heat setting temperature is increased. Also is at a Hitzefixiertemperatur of 150 ⁰ C, which represents the minimum lernparatur that, for example, enough so that the shrinkage at 105 ⁰ C '10 ° / a does not exceed the sufficient dimensional stabilization of the film is necessary, the elongation at break in the neighborhood of only about 5 to 7 $> ₉ and since the film at this limitation of the elongation, the flexibility is lacking _f * cleaves the film slightly up and fiberized when any appreciable Zukräften in the transverse direction; is exposed to the direction of stretching, and frayed easily when it is hit. In addition, the elongation at break at the higher and more preferred heat fix temperatures, e.g. B. at 200 ° C, even lower, and

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the risk of fraying becomes even greater

Ee was now surprisingly found is that a film of polyethylene terephthalate not fraying, dimensionally stabilized and vorherrechend stretched in a direction that is not in particular by at least 50 # strength elongation at break in the transverse direction to the direction of νοτ- prevailing orientation and a shrinkage at 105 ⁰ C Overdough, labeled, can be produced. It has been found that a necessary feature of such a film is the combination of an intrinsic viscosity value of at least 0.65 and predominant unidirectional orientation. Such a film exhibits, when it is dimensionally stabilized, high tensile strength in the direction of the prevailing orientation in the amount of preferably at least 3 500 kg / cnr, excellent dimensional stability, as they are no longer ze in a shrinkage value at 105 ⁰ C of 10 #, igt, and a surprising and unexpected pneumatic impact resistance and elongation of preferably at least 50? £ for the bruc in the transverse direction to the prevailing orientation direction

The elongation characteristics in the transverse direction to the prevailing Orientation directions of the film according to the invention are in Fig. 3 is shown, in which the percentage elongation at break

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is stretched against a Intrinsicviscosität at 90 ⁰ C for four times, and applied heat-set at 150 ⁰ C film. The percentage elongation at break is only approximately iq * for a film whose intrinsic viscosity is approximately 0.5; the relationship between the elongation at break and the iet Intrinsicviecoeltät bie to a Intrinsicviscosität about 0.63 to 0.65, at which point the percent elongation at break is approximately 50 i "linear. The percent elongation at break increases rapidly above an intrinsic viscosity of about 0.63 to 0.65 and is about 260 pounds at an intrinsic viscosity of 0.75.

The Uberraechende pneumatiseheSchlagfestigkeit of the inventive film is shown in Fig. A, in which the pneumatic impact resistance against the Intrinsicviscosität a film which has been in turn to stretched four times at 90 ⁰ C and heat set at 150 ⁰ C, let to worn * From Flg . 4 let it be seen that for a film with an intrinsicviacoaity of about 0.5, the impact strength is about 71 kg χ cm / mm; the relationship between pneumatischerSchlagfestigkeit and Intrinsicviscosität is right up tu a Intrinsicviscosität of about 0.65, is the value at which the pneumatischeSchlagfeetigkeit about 79 constant. Above an intrinsic viscosity of approx.

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134 kg χ era / mm.

The resistance to shredding can be assessed by the percentage transverse elongation at break and by the pneumatic impact resistance, as shown in FIGS. 3 and 4. An elongation of at least 50 ¹ A is a critical level, since such a film can withstand transverse stresses without splitting and fraying.

Polyethylene terephthalate films stretched in one direction and belonging to the known state of the art with an intrinsic viscosity of 0.55 and a tensile strength above 3,500 kg / cm fray in the direction of stretching during stretching itself or, if they survive the stretching stage, after heat setting, such as is often shown by "shattering". A Another advantage of the film according to the invention is that it can be used in can be produced in a single-stage stretching process, which enables higher production speeds and lowers the plant costs.

The inventive film is for picture tapes ("video tapes"), Audio tapes, adhesive tapes and other applications where high strength in one direction, resistance to shredding and excellent dimensional stability are required

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become, ζ. B. for metallized pollen. This slide is also useful for the production of capacitors. By using high stretching ratios to increase the rigidity or the flexural modulus of the film, lower thicknesses can be used, oho these difficulties arise with the Konäensatorwiajtelapparat. *

The film stretching by stretching is two-dimensional and therefore preferred. Type of film orientation and can be brought about by any suitable means by: for example, the film between or around a pair or a series of slowly rotating rollers that can be heated to the desired temperature, and then between or around a pair or a Series of rapidly rotating rollers, the speed of which is greater than that of the slowly rotating rollers. The stretching ratio used is preferably more than four, so that a film is obtained whose tensile strength in the stretching direction is at least 3,500 kg / cm ² and which is therefore suitable for areas of application where there is a high level of stress.

The film can be reversed at any temperature within the Berelohe, in a molecular orientation occurs, namely above the transition temperature «further ord-

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tion and below the Kriatallachmelzpuaktes dee polymeric llateriale, ζ. B. above 80 and below 250 ⁰ C. The Te used for stretching and heat setting the film erfinaungegemäeaen "peratureη may be prepared by any suitable HassnmhatD, for example by placing the foil on heated surfaces by application of OTDR 3trahlungeheizkörpern be divided • Inge.

The erfindungsgemäese foil has a Disenffionaatabilieierung, commonly referred ala Hltzefixieruog be subjected by the foil bie briefly to a temperature above 150 and preferably to a temperature in the range of 150 250 ⁰ C is heated. 'Shrink ,. DIEA "raiext _e i _n at 105 C not more than 10 jC.

The degree of restraint or relaxation during heat fixation is determined by the properties required. Around High modulus films for uses where high stiffness and low elongation under load are required, su achieve is a complete tension during the Fixation essential. The film has only a slight tendency to echo in width during bit fixation however, it is preferred to keep the foil in all with the foil coplenary directions * firmly. Where it is mainly due to the

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thermal dimensional stability is important, as is the case with metal yarns and collar stiffening, is a relaxation in the direction the main orientation (that is the direction in which the main. Shrinkage tosw »relaxation occurs), Je naok deo desired ratio of thermal dimensional stability to tensile strength «of up to 15 # permitted.

The for the erflndungsgenässe method used Polyäthylentsrephthalat is obtained, for example in the US Patentsohriften in the catfish described 2465319 "2534028 or 2727882, and melt-extruded at a temperature above 270 ⁰ C through a suitable opening in the usual manner and anechliessend * on quenched below 80 ⁰ C so that the polymeric material obtained in amorphous Folieηfor ".

The following examples, in which all parts, unless otherwise specified, are screwed points, illustrate the invention Further:

example 1

Am polyethylene terephthalate, which is made by solid phase polyoerisatlon genes described in US Pat. No. 2,534,028 (Ieard) * method has been established and an Intrinaicviscosi-

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tat of 0.85 which is transferred from the last Polymrrisationsgefäee in a conventional extrusion apparatus, is heated in the ea to 280 ⁰ C, and bschrecktrommel extruded through an orifice to a maintained at 60 ⁰ C *.

"The average pick of the amorphous polyethylene terephthalate film obtained is 0.13 mm. A square sample of the film with a side length of 10.2 cm is placed on a frame stretching apparatus. and the two other edges of the film sample are each held by one of the two movable sides of the frame stretcher. The film sample in the frame stretcher has an effective elongation of 3 inches along each edge held by the frame stretcher heated in an oven to 97 ^° C. and stretched in one direction only to a length of 30.5 cm by moving the two movable sides of the frame stretching apparatus apart at a stretching speed of about £ 21,000 per minute.

The film sample stretched four times in one direction is fully clamped in frame and heated with air

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of 150 ⁰ C for about three minutes hitse fixed .

The foregoing procedure is carried out using poly-. ethylene terephthalate different at IntrinsicviscQsität
the same temperature and stretching conditions from & he ^{repeats the conditions specially given in Table 1} · The properties · * | The shafts of each oil sample are shown in this table.

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Example 2

A roll of an invention, 0.0127 mm thick, in one Direction of stretched and heat-fixed η film with an intrineic viscosity of 0.85 is in a conventional vacuum metallization device at a pressure of 0 * 9 microns and below Use of a resistance heated evaporation crucible at f

a film speed of 61 m per minute with aluminum Metallized / Samples of the metallized foil are coated on the metal-coated side with an adhesive-coated sheet of a similar but non-metallized foil laminated into a sandwich-like structure, the middle layer of which is the metal layer. The laminar structure is in Split 0.396 mm wide strips. The metalized yarn produced therefrom shows good luster and excellent adhesion and frays as a result of fraying of the base yarnβ or the gap edges practically do not appear.

Example 3

Samples of the metallized films according to Example 2 are in conventional way of making electrical capacitors wound on a condens at orwicke lvorr ichtuncj. The foil shows excellent rigidity and can be processed smoothly;

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Tabel

Intrinsic " viecoeität

0.55 0.6a

0.74 0.85 1.0 1.18

VJl • Ρ * -4

Stretching Ratio Heat Fixed «- Stretching Pneumatic

(in a Rieh- parator C in transverse Schlagfeatigkeit birefringence tung reokt). direction kg x cm / mm

4 χ *

4 χ

4 * 4 χ

4 χ 4 χ

150 150 150 150 150 150

7th 71 0.1134 67 82.3 0.1103 248 Η4 -. 507 142.5 0.1096 325 161 '0.1048 - 191 0.0942

β »
οβ

> »» ιο ο

CP

οβ

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In the test, applied voltages which by far exceed the resistance due to η of the film, show no sign of a Vereagens, which indicates the absence of gaps due to the fraying of the base film *

Example 4

A heat-set polyethylene terephthalate film of the present invention, stretched in one direction and having an intrinsic viscosity of 0.85, is used as the basis of a photographic film used in accordance with U.S. Patent 2,698,239 (Alles and Saner). The film according to the invention comes as a base film 12, shown in Fig. 4 and described in Example 12 of the cited patent, for use. After the usual processing, the photosensitive emulsion shows both in wet as well as good adhesion when dry «. Repeated bending neither destroys the bond nor the basic -The foil has been proven to be split or frayed.

Example 5

The erfinduagsgemäese, non-fraying, stretched in one direction, heat-set film with an intrinsic viscosity of 0.85 is used to produce a magnetic recording tape

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turns. A 0.305 m wide roll of 0.076 mm thick polie is used to make the surface more sensitive to adhesion a magnetic coating composition in a known manner pretreated with a conventional solvent mixture of methylene chloride / trifluoro acidic acid. Daa pre-treated sand is applied in carefully controlled layer thickness with the following magnetic treatment

JBisenoacyd (γ) .25 Vinyl chloride / vinyl acetate Hiechpolymerieat 10 Buna-N Kautachuk 2.5% by weight.

Solvent (llethyliaobutyl ketone) 62.5 Qew.jC.

The observed film receives a magnetic orientation in a known manner, it is thoroughly dried and in .508 cm wide strips disassembled. The splitting yields alnd excellent, and ea ea shows no fraying as a result of the very rapid up and down with repeated starting and stopping and rewinding on a magnetic tape drive.

Example 6

A polyethylene terephthalate film with an intrinsic visual coating of 0.65 was stretched in one direction by adding the film

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»I.

form β rallies under the following conditions via slow, idle and fast running

(a) Slow roller temperature - 100 ^° C

(b) ^{Idler roller temperature - 97 0} C (o) Heat setting roller temperature - 180 ⁰ O

(d) The speed of the lung running

Role. - 1.98 m each

Min »

(e) Speed of the high-speed roll

-10.9 m each way.

The most important physical properties in the stretching direction of the sheet structure obtained were as follows

Module 140,000 kg / cm ²

Elongation under a load of 2,460 kg / cm: 2.1 # tensile strength 4,900 kg / cm ² _β

The trueness of the film according to the invention is further enhanced by the following control tests are illustrated in which pollen samples produced in the above-described manner have different stretching ratios and heat-setting temperatures exposed as shown in the table below aind, and the percent longings under a load of 2 460 k ^ / cm were determined »

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Stretching ratio heat setting elongation in the stretching

temperature C direction in

4.4 70 * 14.3 5.0 70 * 4.0 5.5 70 * 3.5 5.5 180 2.1

* Too low for a favorable effect.

The film according to the invention thus has tensile strength properties which cannot be achieved with the films belonging to the known prior art. This ability to resist stretching under high loads depends on both the high stretching ratio and the heat set temperature. In the known films, high stretching ratios lead to fiberization of such films during heat setting.

The term "elongation under load" as used herein is commonly known as "braiding" and in many applications represents z. Plastic pipes, for example, are a critical property. In use, the pipeline is usually durable, mainly due to the pressure of the liquid medium contained in it or transported in it, exposed to stress. When the components of the pipeline, e.g. B. the above

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If the foil were to expand, then obviously the line would also expand, distort, or otherwise change its desired shape. The film according to the invention is also suitable thanks to its low creep values, which are achieved by stretching the film at a high stretching ratio in one direction and then heat-setting at high temperature without fraying, in particular for the production of pipelines. As stated above, the known prior art, unidirectional foils, fray; which have been heat-set in order to achieve low creep values are very severe that they cannot be used with success. Tensile ("teneilized") polyethylene terephthalate films, which by stretching in each of the zv / ei perpendicular to each other. Tungezjs fix heat and post-stretch with a second and a final fixation produced «earth. To illustrate, it should be said that a film held under a tension of 350 kg / cm, the elongation values were extrapolated to 100,000 hours - showed that the tensile strength polyethylene terephthalate film (intrinsic viscosity 0.57) elongated by 0.66 pounds, while the film according to the invention (Intrinsieviscosität 0.65) is yielded only 0.35 # = extended experiments that the increase of the load dieae ^M / erte even can be further diverge so sehliesslich

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the film of the known prior art becomes unusable at the required load of 2,460 kg / cm ^2. The abnormal testing of the pollen according to the invention is carried out by stressing z. B. with 2,460 kg / cm, and measurement of the length and the elongation of the load-bearing film as a function of time with the help of an elongation measuring device connected to an Instron tensile strength testing apparatus (model TT-B, Ibstron Engineering Company, Quincy, Massachusetta) coupled "in general, one observes a Anfangsanpaasung or strain j in the inventive film, the Intrinaieviscosität is 0.65 and the uad gereokt in one direction has been heat-set at 150 ⁰ C, the creep value but is only 2 to 3 1 / 2 # at 10,000 hours »Higher creep values are not permitted for pipe constructions.

The ability of the film ₉ to withstand shrinkage at elevated temperatures is also a critical property in many applications. In some Magnetbandanweneiimgsswecken the temperatures can, for example, up to 60 ⁰ C and get over it, and if daa band more than about 2 $ shrinking t, usually occurs a strong distortion of the captured information on j also occur B £ eehani8che difficulties in handling _t when the shrinking takes place on a roll of tape, for example when the tape is

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The dimensional instability can be measured by hanging a film sample without tension in an oven at the desired temperature and calculating the percentage shrinkage from the initial and final dimensions of the film. This determination is expediently carried out at slightly higher temperatures, for example at 105 ⁰ G, at which a shrinkage of 10 # is the maximum permissible value. in which the temperature of the liquids can be sufficient * to cause shrinkage and distortion of the network of the pipeline.

In the present context, tensile strength is the force or *, the pull per unit of the cross-sectional area, expressed in kg

2 '

per cm, verstaadeng for rubbing the film at room temperature necessary is. The stretch is the auamasa up to which the Foil can be stretched before it breaks when subjected to stress exposed in one sighting at $ 100 elongation per minute becomes «The tensile strength module or» the tensile strength index biodialp which is usually referred to simply as a module and is included in

2
kg per cm is expressed »is the slope of the stress-strain curve © at 1 ig @ r elongation when the film is stretched by TQO # per minute. The three tensile strengths of the film were determined with the aid of an inatron tensile strength test apparatus

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(Model TT-B, Inatron Engineering Co., Quincy, Mass.) By a two inch long and one inch wide sample of film with a Speed of 100 # per minute was stretched. The apparatus provides a stress-strain map from which the appropriate Values can be calculated.

The pneumatic impact resistance, i.e. H. the resistance to breakage in the event of a sudden strike is, for example, in many applications in pipelines, a critical film property “Sudden eye waves in pipeline systems, for example typical water pressure from the rapid closing of the valves can have a disastrous effect, e.g. B. cause the pipeline to tear. The improper Foil structures are characterized by increased pneumatic impact resistance and are suitable for drilling lines useful.

The pneumatic impact strength is the energy required to tear the film and is measured in kg χ cm / mm thickness of the film sample. The determination of the pneumatic impact strength occurs folgendermassenj One measures the velocity of a projectile which is mechanically accelerated by air pressure, first in free flight and then it unmittoXbarfnaohden by rupture of the test sample exerts Foil © eats been braked.

With this test method, the film sample is 4.45 x 4.45 cm, and the projectiles 3 are steel balls with a diameter of 1.27 cm and a weight of 8.3 grams the ball in free flight measures 40+ meters per second. The speeds are determined by photoelectric time measurement of the Passages of the steel balls between light beams that are at a measured edge distance from each other. The pneumatic impact resistance results from the loss of kinetic energy of the ball due to the tearing of the film sample and is calculated from the following formula:

(Square the square of the constant x (speed - speed

(in free flight in braked plug,

The constant is directly proportional to the weight of the projectile and inversely proportional to the acceleration due to gravity nal.

The determination of the Intrinsicviscosität erfindungsgemäesen polyethylene terephthalate film is performed using a one percent solution at 30 ⁰ C in a solvent, dae 25 weights parts Trifluoresaigsäure (TFA) and 75 weight parts of methylene chloride containing (CH ₂ CL _2).

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Claims (1)

ο. Heat-fixed ρ non-fraying polyethylene internal phthalate film, characterized by a predominantly uniaxial, molecular orientation due to stretching by at least four times, an intrinsic viscosity of at least 0 »65», a tensile strength of at least 3,500 kg / cm and shrinkage 105 ⁰ C, dia 10 fo in the direction of stretching does not exceed, and at least 5O $ strength at break in the transverse direction to Reckrichtungβ ο Film according to claim 1, characterized by an elongation less than 3.5 # in the direction of molecular orientation under a load of 2-460 kg / cm. β film according to claim 1 or 2, characterized by a pneu ~ matic impact strength of at least 78j8 kg χ cm / mm. ο film according to one of claims 1 to 3, characterized by a binder or metal coating, or one made therefrom Metal thread. A method for producing a film according to any one of the claims BAD ORJGJNAL _β25 009886 / 20S8 F-1547 1 to 4, characterized! that an amorphous polyethylene terephthalate film with an intrinsic viscosity of at least 0.65 is predominantly uniaxially molecularly oriented by stretching the film at least four times ^{at a temperature above 80 ° C .;} and the film is dimensionally stabilized by heat setting _β 6. The method according to claim 5, characterized in that the heat setting at 150 to 250 ⁰ C is carried out. 7. The method according to claim 5 or 6, characterized in that the film is clamped during the heat fixation holds, 8ο Method according to one of claims 5 to 7 »characterized in that the amorphous polyethylene terephthalate film is produced by extrusion at 270 to 315 ⁰ C and quenching below 80 ⁰ C = 9 · Method according to one of claims 5 to 8, characterized in that " indicates that the expansion is effected by stretching or rolling. 009886/2068 - 26 - Blank page