DE1404478C - Method of heat treating a biaxially oriented film - Google Patents

Description

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the lower, the more uniform the film with regard to the implementation of a heat deseiner, if necessary optical properties is. voltage.

The process does not require any additional complications. The following examples are intended to further enhance the invention

adorned devices and has the further explanations.

in part that it enables the production of a biaxially oriented 5 B bis die 1 1 film of the specified type which has balanced physical properties; The properties of a non-oriented polyethylene terephthalate film are, for example, uniform with a cross-section such that the film body ßige thickness, yield point, modulus, birefringence, a width of about 39 cm and a thickness of about the breaking point in the transverse direction of the web - io 0.9 mm with edge thicknesses of about 2.80 mm in one. Under the birefringence the difference in width is about 3.2 mm, was ^{biaxially stretched three times at 80 to between the maximum and minimum refractive 100 0} C, indices in a given plane of an anisotropic. The biaxially stretched film was then at to understand about translucent material. Heat-fixed 185 ° C and under a tension of 15 According to a preferred embodiment, the 5.27 kg / cm ² for 3 minutes is at about 120 ⁰ C modifi method of the invention in the manner performed sheet. A sample of the film obtained in this way showed that when the film was passed through more than one change in birefringence from edge to edge of the buffer zone, the film in the first buffer zone was 0.03.

Temperature of at least 100 ⁰ C below the temperature, which was used in the implementation of the heat-20 non-oriented film according to the same method.

f jxierung is complied with, is held while the driving is treated, but one after the sideways

The temperature of the film in the remaining buffer zones allowed the film to stretch for about 8 seconds

between the temperature of the first buffer zone and that of a temperature of 25 ° C. The movie was

Temperature, which is then, as described above, heat-setting and heat-heat setting is adhered to. 25 relaxed. A sample of the resulting film

The film in the buffer zone is expediently exhibited a change in the birefringence of the edge

neither at least 100 ⁰ C below the temperature, to the edge of only 0.01.

which is used for heat setting, or similar results have been obtained when a

half 100 ⁰ C, 'but at least 1O ⁰ C below the aqueous gelatin layer applied and this before the

Heat setting temperature held. When the tem- 30 modification of the heat-set film dried

temperature of the film is kept above 100 ° C, so was.

it is advisable to keep the temperature between 45 and B e i s d i e 1 2 75 ° C below the heat setting temperature

keep. If the temperature of the film at least a non-oriented polyethylene terephthalate film 100 ⁰ C below the heat setting temperature overall will hold 35 having a width of about 58.70 cm and a thickness of, it is appropriate one or more of about 0.229 mm, at a temperature of 80 additional buffer zones to be provided. up to 90 ° C first in the longitudinal direction and then in the transverse direction is particularly suitable for the heat treatment of biaxially oriented stretches by three times the biaxial direction. The biaxially stretched film was then heat set at a final thickness of 40 polyethylene terephthalate films for 0.2 minutes at about 215 ° C. One from 0.05 to 0.25 mm. The inventive test of the film obtained in this way showed the following, but it can also be used for other films made of different linear polyesters such as: B. to measure at the edges of the film in the directions of films made of high-melting, poorly soluble, usually microcrystalline, cold-drawable, .hochpolymeren 45 of the film in the +45 or -45 ° to the longitudinal direction of the main plane: esters of terephthalic acid and glycols of the series ρ . ·. - _t g .5 ^. _Ä

HO (CH ₂ ) "OH, where η is an integer from 2 to 10 Young's modulus. '.'. '.'.". '.'. ". '.'. '.'. '.".'. " 22 500 kp / cm «

means. _n,. ■ r. _o .

The residence time of the film in the buffer zone is code · · · · ^υ /> ■

usually 0.01 to 5 minutes. 5 ° A second sample of the same film was made as

In the method according to the invention, the. described above, treated, however, after

Heat setting preferably after the stretching, the transverse stretching and before the heat setting

of the film in the transverse direction. Therefore the film was kept at 120 ⁰ C for 0.1 minutes,

preferably when carrying out the procedure. The lateral tension and the longitudinal

the longitudinal stretching prior to stretching 55 tension is essentially the same as it was after

carried out in the transverse direction. second stretching prevailed, d. i.e., the biaxial

The stretched film according to the invention was kept in such a way that it retained its treatment provided since the process in a buffer-borne dimension, while it is conveyed onward in an additional zone in such a way that its longitudinal dimension is not carried out in the direction how it was influenced in a known way at the age of 60. A sample of the resulting stretching and heat setting is used. Da- Films showed the following differences: the physical properties of the polymeric material, measured at the edges of the extrusion, can be measured through a series of zones of film at angles of +45 and -45 ° to the longitudinal, through a Zone in which there is a longitudinal direction in the main plane of the film: stretching, and then through a 6 ₅

Zone in which transverse stretching takes place, resulting in a strength of 490 kp / cm ²

the heat treatment according to the invention follows. Young's modulus 12,000 kgf / cm ²

Then the heat setting takes place and finally stretching 90%

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B e i s ρ i e 1 3 the following differences in the physical properties, measured at the edges of the film below

A non-oriented polyethylene terephthalate film at angles of +45 and -45 ° to the longitudinal direction in

with a width of about 58.70 cm and a thickness from the main plane of the film:

about 0.178 mm was initially in the longitudinal direction and 5. "

then in the transverse direction at 80 to 90 ⁰ C each around the ilf ^stl ? ^k . ^e .. · ■ ·· '; ,. '™ , ^p ( ^cm "

Triple biaxially stretched. The biaxially stretched modulus of elasticity 14 250 kp / cm ²

Film was then, 0.2 minutes at about 200 ⁰ C strain, 78 / _0th

heat set. A sample of the resulting film. .

showed the following differences in the physical io example

Properties, measured at the edges of the film, A non-oriented polyethylene terephthalate film

at angles of +45 and -45 ° to the longitudinal direction with a width of about 58.70 cm and a thickness of

in the main level of the film: ι. about 0.178 mm was at 80 to 90 ⁰ C in first

. . ₂ lengthways and then crossways in each case

strength 900 kp / cm _{15 the three fac} | _{ie b} i _axia | stretched. The biaxially stretched one

The modulus of elasticity 17 700 kp / cm ² _Fi , _{m then became 0> 2 minutes at about 2} ± ₅ ° C

Elongation V * .y _a . heat set. A sample of the resulting film

A second sample of the same film was produced as before- showed the following differences in physical

Treated as described above, with the exception of properties measured at the edges of the film

that after the transverse stretching and before the heating 20 at angles of +45 and -45 ° to the longitudinal direction

fixing (which only took 0.1 minutes) the film in the main layer of the film:

Was held at 140 ⁰ C for 0.1 minutes, wherein. ~> -, n ν 2

one the lateral tension and the longitudinal tension strength 1 270 kp / cm

held essentially at the value as it was after the modulus of elasticity of 2800 kg / cm

second stretch was reached, that is, the biaxially stretching 25 129 / _0th

A second sample of the same film as previous dimension while being described, handled, with the exception that its length dimension was not that after transverse stretching and before the heat was affected. fixation (which lasted only 0.1 minutes) of the film A sample of the film obtained in this way showed that it was held at 205 ^° C. for 0.1 minutes, during the following differences in the physical properties - the tension in the lateral direction and in longitudinal shafts, measured at the edges of the film under direction remained essentially the same as angles of +45 or -45 ° to the longitudinal direction in was reached after the second stretching, that is, the main plane of the film: the biaxially stretched film was held so that . ,. , -, ₂ 35 its lateral dimension remained the same while

vehemence ······ ·> ™ κρ / cm _{to jhn SQ we} i _t e _r conveyed that his Längsab-

Young's modulus 1125 kg / cm ² _{Measurement not heeinüu} £ _{t was}

Strain 57 / _{0th £ ine sample of Fi} i _{ze ms} i _g t _e the _{thus obtained}

. . . the following differences in the physical properties

B e 1 s ρ 1 e _{4o scna} f _teri) measured at the edges of the film below

A non-oriented polyethylene terephthalate film at angles of +45 and -45 ° to the longitudinal direction in the

with a width of about 58.70 cm and a thickness main plane of the film:

mm of about 0.178 was at 80 to 90 ⁰ C in first. ₂

^Longitudinal and then transverse by £ f stI? *? * ·········· \ 130 kp / cm ^

stretched three times biaxially. The biaxially stretched 45 modulus of elasticity 23 900 kp / cm-

The film then became 115% elongation at about 200 ° C for 0.2 minutes.

heat set. A sample of the resulting film. .

showed the following differences in the physical example

Properties measured at the edges of the film A non-oriented polyethylene terephthalate film

at angles of +45 and -45 ° to the longitudinal direction 50 with a width of about 58.70 cm and a thickness of

in the main plane of the film: about 0.178 mm was initially ^{at 80 to 90 ° C}

"... _nnn,. “In the longitudinal direction and then in the transverse direction, respectively

E? ^St l? . - ♦ "* * y; τ-7? SS l ^{V Cm} three times stretched biaxially. The biaxial

Elastic modulus 17 700 kgf / cm ² _{stretched film was} then applied for 0.2 minutes

Elongation Vl / ₀ . ^ _about 215 ⁰ C heat-set. A sample of the

A second sample of the film was made as above the film showed the following differences in the

described, treated, however, according to the physical properties, measured at the edges

Transverse stretching and before heat setting (that of the film at angles of +45 and -45 ° to the

only takes 0.1 minutes) the film for 0.1 minutes lengthways in the main plane of the film:

held at 175 ⁰ C, with the lateral tension and the 60. ,

Tension in the longitudinal direction essentially £? ⁸ "? ~ Ί ^ι ·· * ■■;«. ^ F ^{p /} , ^cni 2

remained the same as they were after the second modulus of elasticity 22 500 kp / cm ²

Stretching have been achieved, ie, the biaxially stretched. Elongation l iu / ₀ .

Film was held in such a way that it became sideways off a second sample of the same film as

measurement was maintained while it was carried on as described previously, treated, however, after

Portiert that its dimension in the longitudinal direction of the transverse stretching and before the heat fixation

was not affected. (which only lasted 0.1 minutes) the movie 0 ,! Minutes

A sample of the thus obtained film showed the at 6O ⁰ C and then 0.1 Minulcn at! 35 ⁰ C

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held, with the tension in the side and in the longitudinal direction remained the same as it was after the second stretching

direction remained essentially the same as it was reached, i.e. i.e., the biaxially stretched film

after the second stretching was achieved, d. i.e., was held to be its lateral dimension

the biaxially stretched film was held so that it retained while it was advanced so its lateral dimension was maintained while it was 5 so that its longitudinal direction was not affected,

transported so that the longitudinal dimension. A sample of the film thus obtained showed the

was not affected. the following differences in the physical properties

A sample of the resulting film showed the shafts, measured at the edges of the film below

the following differences in the physical intrinsic angles of +45 or -45 ° to the longitudinal direction in the shafts, measured at the edges of the film under the main plane of the film:

Angles of +45 or -45 ° to the longitudinal direction in _. . . _ ",,,,

the main plane of the film: strength 725 kp cm

'. . Young's modulus 13,000 kgf / cm ²

Strength 550 kp / cm ^2, elongation 74%.

Young's modulus 8440 kgf / cm ²

Elongation 56%. B e i s ρ i e 1 8

. -I ₇ A non-oriented polyethylene terephthalate film

B e ι s ρ ι e 1 7 _{with e} j _{Qem so} i _chen cross-section that the body of the

A non-oriented polyethylene terephthalate film film was approximately 39 cm wide and a thickness of approximately having a width of about 58.70 cm and a thickness so 0.9 mm, with the edges having a thickness of about

from about 0.178 mm at 80 to 90 ⁰ C was initially in 2.8 mm to a distance of about 3.2 mm from the

In the longitudinal direction and then in the transverse direction, each calculated around the edge, was biaxially stretched,

stretched three times biaxially. The biaxially stretched three times three times at one temperature

The film was then heated to 80 to 100 ° C at about 215 ° C for 0.2 minutes. The biaxially stretched film heat set. A sample of the resulting film as was then at a temperature of about

showed the following differences in physical heat set and at a temperature of 185 ° C

Properties measured at the edges of the film for about 120 ° C for 4 minutes under a tension of

Heat relaxed at angles of +45 or -45 ° to the longitudinal direction 5.27 kp / cm ² . A sample of it

in the main plane of the film: the film obtained showed a change in the double

_. ,. “30 edge-to-edge refraction of 0.03.

strength 1 270 kp / cm _{a second sample of the above} ,

Young's modulus of 28 00 kg / cm ^{2 of the} _{non-oriented film was made according to} the same

name liy / ₀ . Procedure, but with the exception that

A second sample of the same film was How-after lateral stretching of the film described above, during a treated, but it has been held after 35 time period of about 8 seconds at a temperature of the transverse stretching and before the heat fixation of 88 ⁰ C. The film was then (which lasted only 0.1 minute) the film was heat-set at 115 ° C. for 0.1 minutes and then heat-relaxed for 0.1 minutes at 155 ° C. in the manner described above. A sample of the obtained was held, the stress in the lateral film showing a change in birefringence from direction and lengthwise essentially the 40 edge to edge of only 0.01.

Claims (2)

1 2 these films can be used as packaging materials or the like. Claims: the optical and physical properties of the plastic films, which have previously been 1. Process for heat-treating a biaxially conventional biaxial orientation and heat-fixation-oriented film from a linear polyester, S longitudinal process are obtained, however, for particularly polyethylene terephthalate, the particular uses of the films, for example by heat stretching both longitudinally and when used for production from photographic also transversely oriented film subsequently phical materials, not satisfactory. It is assumed in the heat stretching of a heat setting that the optical defects of the films known hitherto and possibly subsequent heat dissipation are due to the fact that they are subjected to tension, characterized during the stretching in the transverse direction, if it is evident that after the heat stretching, the film in a direction of 90 ° to the stretching, but before the heat setting, the film is moved through direction, the middle part of the film is passed behind the at least one buffer zone, in the edges of the film, which are maintained by the stretching pre-conditions such that noticeable 15 direction and pulled forward, subsequent changes in the film dimensions are lost. As a result, the molecular orientation is avoided and the temperature of the film is not uniform in all directions, which leads to the fact that optical irregularities occur at a substantially constant temperature for a period of at least 0.01 minutes. This optical irregularity is maintained at temperature which is above 20 ⁰ C, but not compensated 20 of the subsequent heat setting of at least 10 ⁰ C below the temperature, but rather only fixed so that is, the heat in the practice of - The resulting film for photographic purposes is adhered to fixation. is completely unsuitable. 2. The method according to claim 1, characterized in that the object of the invention is to provide a method for indicates that when the film is passed through, heat treating biaxially oriented films more than one buffer zone of the film in the first to indicate a linear polyester, in the case of the films Buffer zone can be obtained at a temperature of at least, no optical deficiency -100 ° C below the temperature, which at times have more, so that they are also suitable for photogra implementation The heat fixation can be used for phical purposes. is maintained while the temperature of 3 ° The object is according to the invention with the one film in the remaining buffer zones between the above-mentioned process for heat treatment Temperature of the first buffer zone and the temperature of a biaxially oriented film made of a linear rature is that solved in the implementation of the heat polyester that after the heat fixation is adhered to. Stretching, but before heat setting, the film 35 is passed through at least one buffer zone in which conditions are maintained such that noticeable changes in the film dimensions are avoided and the temperature of the film during a The invention relates to a method for Wärmebe- period of time of at least 0.01 minutes on a biaxially oriented film of a 40 substantially constant temperature is maintained in the act, linear polyesters, especially Polyäthylenterephtha- which is above 20 ⁰ C, but at least 10 ⁰ C lat, the temperature being maintained by heat stretching below the temperature that is maintained in the case of the film oriented longitudinally as well as in the transverse direction using the heat setting,
subsequent to the thermal stretching of a heat. According to the method of the invention, in which the fixation and, if necessary, subsequent heat- 45 temperature of the film in the buffer zone at a relaxation is subjected. Temperature within the range from 20 to below Biaxially oriented plastic films are known already sawn 9:30 ⁰ C, the heat setting temperature is maintained. Such films are, however, proportionate, it is possible for the first time to have a uniform molar unstable and tend to shrink under the influence of spherical orientation and uniform optical inherent heat, the shrinkage being achieved in the subsequent uniform . In order to remedy this disadvantage, the heat setting stage must be fixed. As a result, biaxially oriented plastic films are more normal - it is possible to subject optically perfect polyester films to heat setting, which can be produced at a higher temperature, in particular polyethylene terephthalate films, than the stretching, which is also used in the photographic field, whereby the molecular orientation (crystallization 55 Which is retained according to the method of tion) without the polymer melting the improvement in the optical melt which can be achieved in the process. In this way, the properties of the films treated according to the invention against the action of high temperatures are constantly ascertained from the examples given below. in which the physical properties, It is also already known that biaxially oriented films 60, in particular the birefringence values, are invented a linear polyester then followed by the duly heat-treated films with the de-heat stretching both in the longitudinal and in the speaking properties of a known manner in the transverse direction of a heat setting and given treated films are compared. A comparison of the if a subsequent thermal release to the physical data given in these examples subject. 65 shows that according to the method of the invention The films that are more uniform to be treated by the previously known processes are obtained than by the th oriented films have a process that is known to some. It must be taken into account Purposes sufficient dimensional stability, d. That is, the deviation of the birefringence is so