DE2428464B2 - Biaxially stretched and heat-bonded multilayer film and its use - Google Patents

Description

The invention relates to a biaxially stretched and heat-bonded multilayer film with a Outer layer A and an outer layer B made of crystalline, aromatic, saturated, linear polyesters with different properties.

Polyester films are used as supports for photographhiche Films known They have good transparency, high mechanical strength, high heat distortion temperature, chemical resistance and inertness to photographic emulsions. However, if a photographic emulsion comprising a hydrophilic polymer, e.g. B. contains gelatin as a binder on the Surface of a polyester film is applied, occurs due to considerable shrinkage and disintegration phenomena, caused by the moisture, a twisting of the film on. Since that Turning in a decrease in performance when enlarging and causing copying work, there is an interest in Films that do not twist. The screwing in occurs when there is excessive drying. I the The emulsion-coated surface forms the inner surface of the curved material. So far an attempt was made to avoid the undesired twisting by increasing the thickness of the polyester film or that a twist preventing mint was applied to the surface of the polyester film became. However, these measures increase the cost of the carrier material and lead to complications the production.

There are also multilayer films of the type mentioned above are known (z. B. DE-AS 11 34 503, DE-OS 16 94 404, CH-PS 3 95 530). In the case of such multilayer films, at least one of the outer layers can Particles with a particle diameter of e.g. B. 4 μη) included to make the slide writable. In CH-PS 3 95 530 it is stated that it is on a good flat position the film arrives About how this flatness can be achieved when there is a risk when using the films of penetration occurs in the sense set out above nothing can be found in the publications.

In US-PS 3416 991 and in this corresponding GB-PS 10 91 588 describes a multilayer tape which runs along each side edge and is curled perpendicular to the stretching direction. B. a laminate consisting of two layers, namely an unstretched film made from a homopolymer of ethylene terephthalate and of a film made from a copolymer of ethylene terephthalate and ethylene isophthalate with a ratio of terephthalate to isophthalate in the range of 6: 4 (weight basis) indicated (see example 10 of US-PS 34 16 991). These

Foil shows a twisting, which is probably on the Difference between those forming the two foils Polymers is due Furthermore, in example 2 of this US-PS a multilayer

term film indicated, in which a twisting of the film on the difference in the fundamental molar viscosity between the sliding component of polypropylene with an intrinsic viscosity of 0.53 and the layer component from polypropylene with an intrinsic viscosity of 1.09. However, this is actually not the case, since, as indicated in column 4, lines 72 to 74 of the US-PS, the layer with the low intrinsic viscosity is arranged on the concave side of the multilayer film, while the Layer with the higher intrinsic viscosity is present on the convexly curved surface

In the multilayer film known from US Pat caused, with an excessive heating of a such layer material does not guarantee the development of a twisting

The plastic material obtained according to the above-mentioned US-PS with screwed-in side edges is used as packaging material, handicraft or handicraft material, tire cord or as decoration material used However, this material does not have sufficient rigidity and also does not have an outer surface a satisfactory resistance to weathering and abrasion obtained using a liquid

so coating composition can be coated in such a way that a uniform and smooth layer coating is obtained is, in particular the liquid materials used a shrinkage or stretching of the Can cause layered film.

The invention is based on the object of providing a multilayer film of the type mentioned at the beginning create that when handling liquid materials that shrink or stretch a Create a polyester layer, do not undesirably

(X) rolls and a smooth and even layer application enabling surface.

To solve this problem, according to the invention, a biaxially stretched and heat-solidified one multilayer film of the type mentioned provided that the intrinsic viscosity of the polyester of layer B is 0.02 to 0.5 (100 cmVg) - preferably 0.03 to 0.2 - larger than that of the Material of layer A and that the intrinsic viscosity

Both materials are in the range from 0.35 to 1.0 (100 cmVg) - preferably from 0.4 to 0.9 (100 cmVg) - and that the stretching ensures an F-5 longitudinal value of at least 12.0 kg / mm ^{2 is} made, so that the film is rolled up transversely to its longitudinal axis so that the outer layer of the material with the higher intrinsic viscosity is inside the curvature

The viscosity is measured in accordance with the determination method specified in DIN 53 728. The intrinsic viscosity is then determined in an o-chlorophenol solution of the polyester at 35 ° C and expressed in 100 cm ³ / g. This viscosity measurement is based on the following equation:

15th

Intrinsic viscosity = _c - * d

where T) sp is the specific viscosity of a polymer solution and has no dimension and C is the concentration of the polymer in the solution, expressed by g / 100 cm ^3. This gives the dimension for the intrinsic viscosity 100 cm ³ / g.

The term "F-5 longitudinal value" used above denotes the tensile strength of the film, measured at 5% elongation. To determine this tensile strength, a film ^{sample is stretched by 5 1} Vo at room temperature and a relative humidity of 65% and a pull rate of 100% per minute using a conventional tensile tester, such as an Instron tensile tester, at which point the the force exerted on the specimen is measured and reported in kg / mm ^{2 of} the cross-sectional area of the specimen before the test J5

According to the invention, the F-5 longitudinal value of the polyester ^{layered film is set to at least 12.0 kg / mm 2} by appropriately selecting the stretching conditions for the film

As a result of the values chosen according to the invention for the materials and the stretching, the film is in their latitude, d. H. across its length, screwed in, in such a way that the outer layer with the higher intrinsic viscosity im Located inside the curvature this is due to the difference in shrinkage tension between the Outer layers A and B can be traced back. The difference between the intrinsic viscosities of the two The outer layers are due to the difference in the molecular weight of the polyester materials.

If z. B. the intrinsic viscosity (η) is less than 0.35 (100 cm ³ / g), the degree of crystallization is high and the film is crystallized in the first stage of stretching (stretching in the machine direction, or stretching in the transverse direction), see above that when the second stretching is carried out, the film tends to break. If (η) is higher than 1.0, film formation becomes difficult, then the polymer tends to heat decompose, which requires countermeasures. Therefore, the viscosity of the polyesters is in the range of 035 to 1.0.

If the difference in the viscosities of the polyester materials forming the two outer layers is less than 0.02, the layer support does not twist. On the other hand, the difference bs (η) is above 0.5, the film due to the high difference in the Sc ^K can melzviskosität not coextruded werdea Further, occurs in this case, a layer separation in the film, so that such a multilayer film virtually useless is

The amount of twisting of the film is with a larger difference in intrinsic viscosities between the two outer layers, a smaller difference between the thickness of the two outer layers and a higher heat-setting temperature is larger.

Because of the screwing in, the film has a high degree of rigidity. Screwing in is also otherwise advantageous or at least not annoying. When treating the foil with liquid materials that cause a polyester layer to shrink or stretch will cause the Shrinkage on drying to the point that the twisting is practically eliminated. This is the film is particularly suitable as a support for photographic recording materials, the photographic Emulsion layers are on top of layer A, i.e. the layer with the lower one Intrinsic viscosity

The film can also be rolled up or twisted in by applying another suitable one shrinkable coating layer on the film instead of the photographic emulsion. One such a film is suitable as a writing, drawing or printing film.

The provision that the F-5 longitudinal ^{value is at least 12.0 kg / mm 2} ensures that the multilayer film has sufficient mechanical strength in practical use

The film can consist of the two polyester layers A and B alone. But it can also have a third Have polyester layer C between the outer layers A and B.

The material of the layers is a crystalline aromatic polyester, e.g. B. a homopolyester such as

Polyethylene terephthalate, Polyethylene-2,6-naphthalate, Polytetramethylene terephthalate Polytetramethylene-2,5-naphtha! Ator Polycarbonate,

a copolyester composed of at least 85 mole percent units of one monomer making up the homopolyester and not more than 15 mole percent units of another ester-forming monomers, a mixture of these polyesters or a polymer mixture, which consists of at least 90% by weight of such a homopolyester or copolyester and not more than 10% by weight of another polymer, which practically does not have the excellent properties of the polyester Examples of the polymer that can be used in the polymer blend are Polyamides, like

Voiycaprolactam or Polyhexamethylene adipamide, Polyolefins such as polyethylene, Polypropylene or polybutene-1 and

Vinyl polymers such as polystyrene.
The film achieves superior weather resistance through the use of a mixture of polyethylene terephthalate and polyethylene-2,6-naphthalate for at least one of the outer loops A and B.

The amount of polyethylene-2,6-naphthalate varies depending on the desired properties of the Foil.

Usually the suitable amount is 0.1 to 100% by weight, preferably 0.5 to 30% by weight, and particularly 1.0 to 10.0% by weight. based on weight

the polyester layer A or the layer B.

It is believed that when the mixture of polyethylene terephthalate and polyethylene-2,6-naphthalate formed surface is exposed to sunlight, this surface light of a short time Wavelength range (high energy) due to the content of polyethylene-2,6-naphthalate and absorbed thus inhibits the deterioration of the film

The films can be produced in a known manner. Production is preferably carried out by Coextrusion followed by stretching and heat setting.

When polyethylene-2,6-naphthalate is used as the polyester, it is appropriate to set the F-5 longitudinal value to 16.0 kg / mm ² or more.

The stretch ratio is in the range from 3.5 to 6.0, preferably 4.0 to 5.0, in the longitudinal direction and from 1.5 to 4.0, preferably 2.5 to 3.5, in the transverse direction, wherein the stretch ratio in the longitudinal direction by at least δ.3. preferably at least around 0.7 and in particular is 1.0 higher than the draw ratio in the transverse direction. As a result of stretching the film in the The fact that the stretch ratio in the longitudinal direction is higher than in the transverse direction keeps the film has sufficient strength in the longitudinal direction even if the thickness of the film is reduced very much.

The film can also contain additives, such as, for example, customary stabilizers, matting agents or antistatic agents making means included. The thickness of the multilayer film is usually in the range from 1 to 2000 μπι, in particular 4 to 500 μπι. If the Film consists of two layers, the ratio of the thickness of each polyester layer A and B to that is Total thickness of the layer film in the range from 5 to 95%. With three layers, the thickness of the polyester layer is C. freely selectable. If it is desired to increase the thickness of the entire film, the thickness becomes the Polyester layer C adjusted so that the desired thickness results

In one embodiment of the invention, the film contains - as is known per se - at least in one of the layers A and B particles with a particle diameter of 0.1 to 10 μm, expressed as the arithmetic mean of the diameter of a particle in the direction of the maximum extent and in the Direction of minimum expansion, made of a material from the group of MgO, ZnO, MgCO ₃ , CaCO ₃ , CaSO +, BaSO ₄ , Al2O3, S1O2, TiOi calcium terephthalate, barium terephthalate, zinc terephthalate, manganese terephthalate, carbon black, graphite and / or pigments.

The shape of the particles can be orthogonal or spherical. The particles lead to a good one Slidability of the film.

The particles can be added before or during the polymerization reaction to form the polyester can be added. You can also use the polyester in an extruder when pelletizing after polymerization be mixed. The particles can also be sheeted during the extrusion of the polyester can be added. The amount of the particles to be added varies depending on the properties desired of the layer and is not particularly limited. Usually the amount is 0.01 to 40% by weight, preferably 0.05 to 5% by weight, particularly preferably 0.1 to 2% by weight, based on the weight of layer A. or layer B.

The intrinsic viscosity is a direct measure of that Molecular weight. Thus, a high intrinsic viscosity means a high molecular weight Da a Low molecular weight polyester is easier to crystallize than a higher polyester Molecular weight, the layer of the low molecular weight polyester (layer A) has a higher degree of crystallization than the layer B of the higher molecular weight polyester in the multilayer film. Since a higher degree of crystallization of the layer has a greater resistance to abrasion granted, the surface of layer A has a higher one Abrasion resistance than the surface of layer B.

If particles of an inert material in the polyester layer A (polyester with a lower molecular weight

is large weight) are dispersed, the degree of crystallization of the polyester layer A by the action of inert compound increases because the inert particles promote crystallization of the polyester. In this way can be the degree of crystallization of the layer A and

ία thus significantly increasing the abrasion resistance of the surface of the polyester layer A. A lower molecular weight polyester has a higher terminal carboxyl group content than a higher molecular weight polyester. A layer of the polyester with a lower molecular weight therefore has better adhesion to the added particles of inert material. Thus, the incorporation and dispersion of an inert compound in the polyester layer A is also advantageous with a view to preventing the escape and separating off the added inert compound

The films are suitable for many applications: as Packaging films, molded films (i.e. films of a desired shape, the z. B. for panels in the household are provided), foils for outdoor applications (e.g. for the production of blinds, exterior parts of a house, street signs or the like), electrically insulating foils and foils to be metallized, as a carrier for adhesive tapes, measuring tapes and magnetic cards, when colored for decorative purposes.

Photographic films made using the sheets as supports are useful as Roll films, cinema films, photographic films for plate making, photographic duplicating films, 8 mm cinema films, photographic drying plates, Sheet films and radiographic films.

In this case, since high transparency is desired for photographic purposes, none

Layer of the film incorporated particles.

The foil can also be used as the raw material for the Production of split fibers can be used.

The threads obtained by splitting or splicing are twisted in a spiral, as the difference between the Intrinsic viscosity between the outer layers of the threads contributes to a difference in the snap tension the high temperatures used at the time of cleavage and at the time of swelling Solvents, the heat treatment after the

eo cleavage and heat treatment after Thus, the resulting filaments have superior softness to bulkiness and upper tensile properties, the high tensile strength being knot strength, pulling strength and durability which is generally inherent in polyester fibers, are retained.

Embodiments of the invention are given below

The properties given in the examples were determined using the following measuring methods.

Intrinsic viscosity

Measured in an o-ChlorphenolIösung of the polyester at 35 ⁰ C and expressed in 100 cmVg.

stiffness

The measuring method is based on the F i g. 1 explained in more detail A sample film A with a width of 1.27 cm and a length of 28 cm was taken out in the measuring direction (machine direction). The sample was leveled and a weight B was placed on it. The one between the sagging part C, which was 7.5 cm in length, and the perpendicular angle θ formed was used as a measure of the Taken stiffness of the foil.

Loss of wear and tear

Measured according to ASTM method D I242-52T. Using a Taber wear tester, the amount of wear loss became one Film sample under a load of 1000 g and below Measured using a CS-17 wear ring. The speed of rotation was 70 rpm, and the number of rotations was 1000.

Density of the respective film forming
Polyester layers

Each of the polyesters with different intrinsic viscosity was made under the same conditions Use the same extruder as when coextruding this polyester into a film underneath Forming a film Her same thickness as the multilayer film extruded The density of each of the so obtained films were measured. The measurement was made using a density gradient tube that was filled with a liquid, the density of which was continuously changing. A small The sample of the film to be measured is introduced into the liquid column, this FÜmprobe within the Liquid stops at a certain position, at which the density of the liquid is equal to the density of the film is equal to. The liquid used to measure the density consisted of a mixture of n-heptane and carbon tetrachloride. To determine the densities of layers A and B of the multilayer film foils made of only polyester A alone or polyester B alone were used in each case, with

it was assumed that the density values measured in this way equal the density of the corresponding outer layers, forming the multilayer film are.

Example I.

Polyethylene terephthalate was made using a catalyst of 40 mol% manganese acetate, 20 mmole% antimony trioxide and 40 mmole% phosphoric acid produced, the percentages based on the weight of the starting dimethyl terephthalate are. In this polymerization reaction, inert particles were not added or they became fine ones Kaolin powder with a particle diameter of 1 to 3 μm in an amount of 0.14% by weight or 0.28 wt .-%, based on the polyester weight, added, and there were various polymers with a Intrinsic viscosities of 0.50, 0.65 and 0.85, respectively, which are free from

: isui, i rvai / iiii

UCI ailgCgCUCIICIl ITICIIgC

contained, manufactured.

Then, two polyesters of different intrinsic viscosities selected from the above polyesters were coextruded using a conventional extruder so that the ratio of the film thicknesses would have the values given in Table I, with those in Experiments 1 to 5 being given in Table I. five unstretched polyester films were formed. Each of the unstretched films were stretched first μιη in a ratio of 3.4 in the longitudinal direction and then in a ratio of 3.8 in the transverse direction to form a film having a thickness of 36 and then 30 seconds in hot air at 205 ⁰ C thermally solidified. The stiffness, density and wear loss of the resulting films were measured and the results are shown in Table I.

The films in tests 1 to 5 showed a total of twisting in the width direction, with the Polyester layer with the higher intrinsic viscosity was arranged on the inside of the curve.

The properties of polyester films with different intrinsic viscosities were used for comparison measured. The results are shown in Comparative Examples 1 to 3. These slides are flat. Table I shows that the multilayer films have an increased rigidity compared to the flat individual films exhibit.

In Table I, B denotes a layer with a higher intrinsic viscosity and A denotes a layer with lower intrinsic viscosity.

Table I.

B.
A. attempt
1 No.
2 3 4th 5 Comparative experiment
1 2 ■ Single
foil No.
3 Ratio of the layer thicknesses
(%)
the total film thickness B.
A. 50
50 20th
80 30th
70 50
50 40
60 singles
foil 0.14 singles
foil Amount of added
Kaolin (wt .-%) B.
A. 0.14
0 0
0.28 0.14
0.14 0
0.28 0
0 0.14 0.63 0.14 Intrinsic viscosity of the
Layers (100 cnrVg) 0.62
0.50 0.63
0.49 0.75
0.62 0.77
0.61 0.63
0.48 0.49 0.75

Total thickness of the film

36

36

36

36

ίο

continuation Foil stiffness' * "

A «' ³ '

attempt
1 No.
2 3 4th 5 Comparative experiment
1 2 42.0 No.
3 49.0
46.5 48.0
46.0 47.5
46.0 49.5
47.0 48.0
46.5 42.5 1.3972 43.0 1.3972
1.4015 1.3968
1.4019 1.3955
1.3973 1.3950
1.3975 1.3970
1.4021 1.4015 22.2 1.3950 27.0
25.5 33 ,; »
19.11 23.5
22.0 35.5
22.0 33.5
27.5 17.7 25.9

Density of the layer or the B
Film (g / cm ³ ) A.

Wear loss every B
Layer or Foil (mg) A

'* "The stiffness of each film was measured in the machine direction only.

'' ^2I The stiffness was measured with the surface of layer B facing upwards.

'* · "The measurement of the stiffness was carried out with the surface of the layer A facing upwards.

Example 2

Multi-layer films were produced in the same manner as in Example 1 with the modification that kaolin was added to polyethylene-2,6-naphthalate with an intrinsic viscosity of 0.50 and 0.63, respectively and stretching the film first in the longitudinal direction at a stretch ratio of 3.4 and then in the transverse direction at a draw ratio of 3.7 to form a film having a thickness of 23 μπι was carried out then during 30 Seconds at 230 ° C was heat set. The rigidity, density and wear loss of the foils were measured and the results are given in Experiment 1 of Table II.

For comparison, the properties of individual polyester films were also measured. The results are in the comparative experiments 1 to 2 reproduced. Table II shows that when polyethylene-2,6-naphthalate is used as Polyester was used, the results were the same as in Example 1.

Table II

B.
A. Attempt no.
1 Comparative experiment
1 No.
2 Ratio of the layer thicknesses
(%) of the total film thickness B.
A. 50
50 Single slide Single slide Amount of iiaolin added
(Wt .-%) B.
A. 0
0.14 0.14 0.14 Intrinsic viscosity of the layers
(lOOcm-Vg) - 0.60
0.48 0.48 0.61 Thickness (μπι) R ¹ * - ¹ '
A ¹ " ¹ 23 23 23 Foil stiffness' * " B.
A. 34.0
32.5 29.0 29.5 Density of the layer over the film
(g / cm ³ ) B.
A. <- » r · e \ -v
1.3613 1.3613 1.3596 Loss of wear on each layer
or the slide (mg) 57.9
48.5 49.3 57.1

eil, C2> _and C3) _{mean the} same as in Table I.

Example 3

Polyethylene terephthalate with an intrinsic viscosity of 0.50, 0.65 and 0.85 were made in the same manner as in Example 1 using no inert particles or adding a fine kaolin powder with a Particle diameter of 1 to 3 μm in an amount of 0.14% produced. Using two polyesters selected from these with different intrinsic viscosity were polyester films (Runs 1 to 6) as indicated in Table III, in the same way vie produced as in example 1 In these experiments the films were biaxially successively in the Stretch ratios in the longitudinal and the

Cross direction as indicated in table IN under Formation of films with a thickness of 36 μm stretched and then hot air for 30 seconds, which is applied to the in Temperatures indicated in Table III were maintained, heat set was further carried out in each of the experiments Kaolin was incorporated into the polyester layer A with a lower intrinsic viscosity, and it became none Kaolin in the polyester layer B with a higher

Intrinsic viscosity incorporated The strength, elongation, the F-5 value, the stiffness, density and the Wear losses of each of the resulting films are shown in Table III.

For comparison, the properties of polyester films with the different intrinsic viscosities are also included shown as individual films as comparative experiments 1 to 4 in Table III.

Table III Ratio of the layer
thickness (%) of the film
total thickness lot
kaolin of added
(Wt .-%) Intrinsic viscosity everyone
Layer (100 cm Vg) A. Stretch ratio
(Longitudinal X across) Heat supply
consolidation
temperature B A B. Λ B. (Π 0.50 V Wl 9ULII
No. 30 70 0 0.14 0.63 0.50 3.9 X 3.7 205 1 30 70 0 0.14 0, o3 0.62 4.4 X 3.3 195 2 30 70 0 0.14 0.75 0.50 4.4 X 3.3 195 3 50 50 0 0.14 0.63 0.50 3.9 X 3.7 205 4th 50 50 0 0.14 0.63 0.62 4.4 X 3.3 195 5 50 50 0 0.14 0.75 4.4 X 3.3 195 6th Cf.
attempt
No. Single slide 0.14 0.63 3.5 X 3.8 205 1 Single slide 0.14 0.50 4.4 X 3.3 195 2 Single slide 0.14 0.62 4.4 X 3.3 195 3 Single slide 0.14 0.75 4.4 X 3.3 195 4th

Table III (continued) Physical properties of the stretched films

thickness (Ml. ('21 stiffness Density of the layer A. Wear and tear t (mg) Results of the tensile strength test Fo value (g / cm ¹ ) loss fracture fracture ) (kg / mnr) 1.3987 A. strain strength (lim) B. A. B. B. (%) (kg / mm '; attempt 1.3985 13.6 No. 31 10.5 1 36 52.0 47.5 1.3943 1.3942 40 MD 91 35 15.5 32 TD 133 24 10.9 2 36 55.0 47.5 1.3939 1.3987 42 MD 69 42 15.8 35 TD 135 33 Ü, l 3 36 54.5 47.0 1.3913 1.3985 46 MD 75 43 13.7 32 TD 140 31 10.3 4th 36 544 49.0 1.3943 1.3942 41 MDIlO 36 15.6 33 TD 135 23 10.7 5 36 56 ^ 50.5 1.3939 40 MD 70 43 T59 37 TD 137 32 6th 36 56.0 51.5 1.3913 46 MD 77 42

continuation

thickness

(μπι)

ι " ¹ » '· * ³ · Stiffness density of the layer ⁽ * ³¹ (g / cm ³ )

Attrition Loss (mg)

Tensile test results Break-break F-5 value

elongation strength

(%) (kg / mm ² ) (kg / mm ² )

Cf.
attempt
No.
1 36 36 41.5 1.4013 21 MD 120
TD 99 22nd
24 10.8
11.8 2 36 44.5 1.3985 30th MD 55
TD 130 40
29 15.1
10.9 3 36 45.0 1.3942 35 MD 57
TD 135 42
31 15.8
10.7 4th and ⁽ * ³⁾ in T 46.0 U916 39 MD 60
TD 137 44
34 15.6
10.8 CD.C2) abelle III mean same as ill table I.

Example 4

Polyethylene ^ e-naphthalate polymer with an intrinsic viscosity of 0.57 and polyethylene terephthalate polymers with an intrinsic viscosity of 0.65 and 0.55 were prepared in the same manner as in Examples 1 and 2. Then the above polymers were made coextruded by a common coextruding machine, so that the films obtained had the polyethylene-2,6-naphthalate content indicated in Table IV and the thickness of each layer was as shown in Table IV. There were two unstretched Polyester films (experiments 1 and 2) produced. Each of the films was then cut in the longitudinal direction a draw ratio of 3.6 and then in the transverse direction at a ratio of 4.1 to form a film with a thickness of 45 μm and then stretched for 30 seconds with hot air at 215 ° C heat-set. The intrinsic viscosity and the rigidity of the obtained films were measured. the Polyethylene terephthalate layer surface and the surface made of polyethylene terephthalate / polyethylene-2,6-naphthalate of the foil were each attached to a high pressure mercury lamp as a substitute for sunlight exposed for predetermined periods of time, and then the strength and elongation of the so treated film measured. The results are given in Table IV.

The films in tests 1 and 2 were twisted in the width direction after heat consolidation, wherein the layer with a higher intrinsic viscosity was arranged on the inside of the curve.

For comparison, the results are with a film made only of polyethylene terephthalate without the addition of Polyethylene-2,6-naphthalate existed, shown in Table V as Comparative Experiment 1. Even after thermosetting was this slide. The multilayer films using a mixture of Polyethylene terephthalate and polyethylene-2,6-naphthalate had a very high stiffness compared to the flat individual film due to the twisted shape Table IV clearly shows that the films, which are a mixture of polyethylene terephthalate and polyethylene-2,6-naphthalate contained, had very good weather resistance, which is reflected in the results Irradiation with a high pressure mercury lamina aul the surface of the polyethylene-2,6-naphthalate-containing film was shown.

In Table IV, B means a layer having a higher intrinsic viscosity and A means a layer

so with a lower intrinsic viscosity

The intrinsic viscosity of the layers A and B was measured on samples that were separated at the time dei Melt extrusion were taken.

Table IV

Attempt no.

PEN content in polyester layer B
(Wt .-%)

internal sink viscosity (lOOcmVg)
B / A

⁽ * ²⁾ B 48.5

⁽ "Stiffness, (· ') a 455

0.594 / 0.504 48.0
45.5

15th

continuation

Attempt no.
1 TD (PET + PEN)
MD
TD 324
1920 2 TD (PET +
Ml PEN)
TD Relationship ί ^ΡΕΤ ) 50/50
PET
MD 71.2
2600 44.3
1970 70/30
PET
MD 70.0
2940 [a) ^ pet + pen)
Irradiated film area ^(M)
direction 1053
2160 254
1750 58.6
1580 100.3
2140 13.4
1350 494
1450 21.3
1690 Exposure time (h)
Empty test (O) elongation at break
Breaking strength
(kg / cm ² ) 2.7
830 17.3
1470 453
1430 23
690 19.3
1200 15.4
1120 21.0
1490 60 elongation at break
Breaking strength
(kg / cm ² ) 1.9
680 1.8
610 120 elongation at break
Breaking strength
(kg / cm ² )

Footnote: ⁽ * "· ⁽ ' ²⁾ and ⁽ ' ³⁾ mean the same as given in Table I. MD machining direction and TD = transverse direction. PEN polyethylene ^ o-naphthalate, PET = polyethylene terephthalate.

· ** 'The surface from which the irradiation was carried out.

Table V component Intrinsic viscosity (lOOcnrVg)

Stiffness'*"

Irradiated film surface

direction

Exposure time (h) Empty attempt (0)

60

120

Elongation at break (%)
Breaking strength (kg / cm ² )

Elongation at break (%)
Breaking strength (kg / cm ² )

Elongation at break (%)
Breaking strength (kg / cm ² )

Comparative example MD I. 93.6 PET alone 2580 0494 16.3 41.8 1360 PET 1.8 MD 720 102.3 2440 2.1 750 1.8 680

PET polyethylene terephthalate MD machining direction (longitudinal direction). TD cross direction.

'* "The stiffness of the film was only measured in the machine direction.

Example 5

A film with an intrinsic viscosity of 0.61, the was obtained by extruding polyethylene terephthalate alone, and a film with an intrinsic viscosity

_S jtat of 0.56 obtained by extruding polyethylene terephthalate alone was laminated by the co-extrusion method to form a multilayer film, the ratio of the thicknesses being

both layers was 30:70. The slide became biaxis.! stretched first in the longitudinal direction at a ratio of 3.0 and then in the transverse direction at a ratio of 3.3 and then heat set for 30 seconds at JIO ⁰ C at a constant length to form a film with a thickness of 100 µm

A primer layer containing a hydrophilic copolymer of vinyl acetate and maleic anhydride, was on the raised (convex) part (surface at the lower Intrinsikvislcosität) applied to the film and dried at 60 ⁰ C for 10 seconds, followed by Wärnieverfestigung for 7 minutes at 130 ° C connected. Then, an ordinary silver halide emulsion for negatives was coated thereon to a thickness of 20 µm and dried

For comparison, a single film with an intrinsic viscosity of 0.61 and the same thickness was used prepared under the same film production conditions and under the same conditions as above indicated, the primer coat and the sulfide halide emulsion were applied for a photographic negative - atcriai on a surface of the single-layer FeSe The coated multi-layer film and the stripped single-layer film each became one

Table Vl

subjected to photographic development. The extent of twisting the film was made after the film was obtained at a predetermined humidity and measured after development. The results are shown in Table VI.

The twist value used in Table VI was measured in the following manner. A circular sample with a diameter of 100 mm became from the film, its twist value

to be measured, cut out. Man UeU the Sample at a certain relative humidity for 48 hours to develop the twist stand. Then the screwed-in circular sample was placed on a flat plate, for example a glass plate brought the screwed-in part at the bottom, this sample with the flat plate at two Points on the perimeter came into contact. The distance (X mm) between the two points was measured using measured by a cathetometer. The rotation value is now expressed in (100-X) The rotation against the emulsion-coated surface was indicated by + and the twist against the opposite Surface through—. The results are given in Table VI.

Support

Rotation value ^ before development ** ¹ '

30% RH *) 70% RH

Turning value
after development '' ²¹

30% RH 70% RH

Example!
Comparative example

multilayer film * - 1.3 -0.3

Single slide il-17.0 +6.1

/ ι RH equals relative humidity

'* "Film, dried, after mixing and measuring before development. ^R2> Film after standing in low humidity, measured after development.

+ 2.1
+ 164

+0.3
+ 5.3

From the results of Table VI it can be seen, that the photographic films made using; of the multi-layer foils produced as a carrier: were considerably reduced in size; Showed turning.

Example 6

A film with an intrinsic viscosity of 0.62, the by extrusion of polyethylene terephthalate alone was obtained, and a film with an intrinsic viscosity of 0.50, which was obtained by extruding polyethylene terephthalate was obtained alone were processed into a composite film, the ratio of The thickness of the two layers was set to 1: 1, and the film was then stretched in the longitudinal direction at a ratio of 4.0 to a thickness of 90 µm Stretched The film was passed between rubber sheets and pressure was applied to the film in one direction Applied perpendicular to the direction of stretching around the film to form monofilaments with a mean thread of 1600 den to split. The threads were twisted in an atmosphere at 300 ° C to an extent of about 1000 twists each Meters twisted and bundled while the threads partially melted to form a yarn. That Yarn had good knitting and weaving properties and good hand. Furthermore the yarn exhibited excellent softness, bulk, and covering properties when compared to split Fibers obtained from a single sheet formed under the same conditions.

1 sheet of drawings

Claims (3)

Patent claims: 1. Biaxially stretched and heat-bonded multilayer film with an outer layer A and an outer layer B made of crystalline, aromatic, saturated, linear polyesters with different properties, characterized in that the latrine viscosity of the polyester of layer B is 0.02 to 0.5 (100 cmVg) is greater than that of the material of layer A and that the intrinsic viscosities of both materials are in the range of 0 ^ 5 to 1.0 (100cnvVg) and that the stretching while ensuring an F-5-I longitudinal value of at least 12.0 kg / mm ^{2 is} made, so that the film is rolled up transversely to its longitudinal axis in such a way that the outer layer made of the material with the higher intrinsic viscosity is inside the curvature 2. Multi-layer polyester film according to claim 1, characterized in that at least one of the layers contains particles of an inert compound with a particle diameter of 0.1 to tO μπ from the group of MgO, ZnO, MgCXH CaCO ₃ , CaSO <, BaSO ₄ , Al ₂ O ₃ , SiO ₂ , TiO ₂ , calcium terephthalate, barium terephthalate, zinc terephthalate, mangam terephthalate, carbon black, graphite and / or pigments 3. Use of the multilayer polyester film according to Claim 1 or 2 as a support in photographic recording materials, the photographic emulsion layers being on layer A.