US3560606A - Process for preparing drawn polyamide films - Google Patents

Process for preparing drawn polyamide films Download PDF

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Publication number
US3560606A
US3560606A US746889A US74688968A US3560606A US 3560606 A US3560606 A US 3560606A US 746889 A US746889 A US 746889A US 74688968 A US74688968 A US 74688968A US 3560606 A US3560606 A US 3560606A
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United States
Prior art keywords
film
drawn
films
water content
temperature
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Expired - Lifetime
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US746889A
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English (en)
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Mutsuo Kuga
Kayomon Kyo
Takeshi Mashimo
Wakuo Matsumura
Hiroshi Kayama
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Nippon Rayon Co Ltd
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Nippon Rayon Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B29C55/10—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial
    • B29C55/12—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial
    • B29C55/16—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial simultaneously
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2077/00—Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material

Definitions

  • Polyamide film is processed by adding 1 to 6% by weight water, preheating and then biaxially drawing at a temperature at least C. higher than the preheating temperature. During preheating a substantial difference in water content between the interior and surface of the film is created.
  • the films made by this process have a relatively low friction coefficient.
  • a process for drawing a polyamide film which comprises treating the polyamide film with Water, preheating the film to produce a difference of water content between the surface and the interior of the film and drawing the film simultaneously in the longitudinal and transverse direction.
  • the process of the invention it is possible to obtain a polyamide film having uneven reticulated fine projections on its surface, and a low friction coefiicient. Moreover, blocking characteristics are reduced and the processability of the film is improved.
  • the film obtained also has a uniformity of properties.
  • Ratio of draw speeds can be defined as follows:
  • longitudinal draw speed ratio of draw speeds transverse draw speed in which the longitudinal draw speed and transverse draw speed show respectively normal values or mean values of draw speeds in longitudinal and transverse directions from the begin of drawing to an optional point reached in the drawing process. Draw speeds are measured at the said point.
  • the longitudinal draw speed and transverse draw speed can be defined respectively as follows:
  • I and I1 are respectively the length in the transverse direction and width of the drawn film, which are measured after 2 minutes from the beginning of the drawing at an optional point on the film track.
  • the film obtained has unevenly reticulated fine projections (or webs) on the surface and an improved friction coefficient.
  • the method of giving a film a difference of water content between its surface and interior is preferably as follows.
  • a film having the desired water content is preheated in the shortest possible time to a suitable temperature in order to achieve a difference of water content between the surface and the interior. It is then drawn simultaneously in the longitudinal and transverse directions in a drawing zone where the temperature of the atmosphere is higher than the temperature of the preheated film, so that the surface of the preheated film is heated during drawing to evaporate water from its surface and provide a large difference of water content between the surface and the interior.
  • polyamide films includes films made from linear polyamides, for example, poly-E-caproamide, poly-hexamethylene-adipamide, poly-hexamethylene-sebacamide, polyll-aminoundecanamide, copolymerized polyamide, etc.
  • the water-content of the polyamide film is preferably from 1 to 6% by weight before preheating.
  • Preferred amounts of water which are added in the pretreatment of the polyamide films vary according to the types of polyamide film and may for example be within the following approximate ranges:
  • Water content (percent Polyamide by weight of film) Poly-e-caproamide 1-6 Polyhexamethylene-adipamide 1-6 Polyhexamethylene-sebacamide 1-5 Poly-1l-amino-undecanamide 1-3 These values may however vary according to the temperature and other conditions under which the film is treated.
  • the relationship between the water content of the polyamide film before drawing and the surface properties of the films obtained may be as follows:
  • Raw film having too high a water content may give rise to a drawn film having uneven reticulated fine projections (webs) on its surface which may grow gradually and simultaneously result in a decrease of their heights.
  • the friction coefiicient of the film may increase as the water content in the raw film increases.
  • the absorption of water onto the raw film is effected prior to the drawing step, and water is added to the undrawn film, for example, by the use of a water bath, water spray, etc. in order to give a uniform water content to the raw film which may be drawn uniformly. As a result, it is possible to obtain a uniformly undulating surface on the drawn film.
  • the water content is preferably uniformly distributed throughout the film before drawing, for example, by passing the film through an atmosphere maintained at the correct temperature and humidity.
  • a film having the correct water content is then preheated to a suitable temperature and drawn simultaneously in the longitudinal and transverse directions whilst maintaining a difference of water content between the surface and the interior of the film during a drawing process.
  • Improper heating may give rise to an incorrect difference in water content between the surface and the interior of the film. It is therefore necessary to use the shortest possible time to heat the film to the temperature required for drawing. Suitable heating times and temperatures may be determined empirically according to types and dimensions of the raw films.
  • the film may preferably be drawn, at least in part, in a zone where the temperature of the atmosphere is at least 5 C. above the temperature of the preheated film, before the film is drawn such that the ratio between the average thickness of the drawn film and the undrawn film is 0.5:1.
  • the temperature of the atmosphere may be maintained by any suitable method, for example, using hot air, infra-red radiation, etc. After drawing of the film, it may be heat-set for example by heating at a temperature not higher than C. below the melting point of the film with the film maintained under tension such that the transverse direction remains substantially constant.
  • the most advantageous water content of the raw film may be determined by drawing raw films having various water contents simultaneously in the longitudinal and transverse directions and inspecting the surface of the resultant film.
  • a suitable method of inspection is by the photographic determination of drawn polyamide film.
  • a photographic enlargement (X) has been prepared showing the surface of a simultaneously longitudinally and transversely drawn polyamide film prepared from a raw poly-e-caproamide film having a thickness of 200a and a water content of 1.2% by weight of film, and obtained by pre-heating the raw film to C. for several seconds, and drawing simultaneously in the longitudinal and transverse directions with an elongation of 3X3, with a draw speed of 24,000 percent/min., and a draw ratio of about 1 in an atmosphere having a temperature of 160 C. Uneven reticulated fine projections (webs) which are very closely spaced can be observed.
  • An enlarged photographic appearance of the glycerincoated surface of a drawn poly-e-caproamide film obtained by simultaneous drawing in the longitudinal and transverse directions of a similar raw film having a water content of 1.2% by weight shows the difference between the inner and outer structures of the drawn film. It may be seen that the inner structure of the drawn film is similar to that of the transparent film obtained from a raw film which had a water content of 6.0% by weight.
  • the friction coefficient was measured using a commercial instrument designed for measuring the friction coefiicient of textile materials (available from Toyo Sokuki, K.K., Japan) with a slide speed of 0.50 cm./sec., a load of grms. the width of the test strip being 0.50 cm. and the contact length of 2.0 cm., the film surfaces being in contact with each other.
  • a satisfactory method for obtaining improved biaxially drawn polyamide films having a low friction coefficient has not been previously reported.
  • Biaxially drawn polyamide films having low friction coefficients have been obtained by the present invention and the improved polyamide films have a friction coefiicient of less than three.
  • Example 1 Substantially amorphous films of poly-e-caproamidc (relative viscosity 3.0 at 25 C. in 96% sulphuric acid) having an average thickness of 200p are pretreated with water to give the films a water content of about 3% (measured by Karl Fischers method) and density of 1.130. Samples of the films were preheated to 70 C., 80 C., 100 C., 110 0., 140 C. and 160 C. respectively by passing them through a preheating zone, in which the atmosphere was maintained at 170 C. for a suitable time e.g. 3 to 6 seconds. The preheated films were then simultaneously drawn in the longitudinal and transverse directions with a draw speed of about 24,000 percent min.
  • Table 1 illustrates the low static friction coefficient of films prepared by the present-process as compared with film wherein the draw temperature was lower than the preheat temperature.
  • Substantially amorphous films (average thickness 160a; density1.128) of poly-e-caproamide (relative viscosity 3.0 measured at 25 C. in 96% sulphuric acid) were pretreated with water to give the films a water content of about 1.2, 3, 4.5 and 6.0% respectively.
  • the films were preheated to 70 C. by passing through a preheating zone, where the atmosphere was maintained at 130 C. for a residence time of about 4 seconds.
  • the preheated films were then simultaneously drawn in the longitudinal and transverse directions with a draw speed of about 30,000 percent/min. in a drawing zone, where the atmosphere was maintained at 140 C., to draw the films with a magnification of 3 in the longitudinal direction and 3.5 in the transverse direction at a ratio of draw speeds of about 0.6 to 1.0.
  • the preheated film was then simultaneously drawn in the longitudinal and transverse directions with a draw speed of about 24,000 percent/min. in an atmosphere having a temperature of 150 C. to provide a film having a magnification of about 3 in both the longitudinal and transverse direction at a ratio of draw speeds of 1 to 1.2.
  • the drawn film was heat-set by heating for 10 seconds at 190 C. under tension so that its transverse dimensions would be kept constant to give a film 22 in thickness.
  • Microscopic observation of the surface of a drawn film showed that throughout the surface numerous fine uneven Webs (of a height of about l-2 microns) were formed thereon.
  • the static friction coeflicient of the drawn film measured by this method was about 1.0, and the film obtained had improved antiblocking characteristics and its machinability was improved.
  • the film transparency measured at 450 m was 80%.
  • Example 4 A substantially amorphous film (density 1.030; thickness 200 1.) of poly-1l-amino-undecanamide (relative viscosity 2.8 at 25 C. in 96% sulphuric acid) was left in a vessel, in which the atmosphere was kept at a temperature of 35 C. and a relative humidity of to give a film having a water content of about 1.2% (measured by Karl Fischers method).
  • the film was pre-heated to about C. by conventional infra-red heaters in an atmosphere maintained at C. for a period of 2.7 seconds.
  • the preheated film was then simultaneously drawn in the longitudinal and transverse directions with a draw speed of Example A substantially amorphous film (density 1.125; average thickness 150g) of poly-e-caproamide (relative viscosity 3.2 at 25 C. in 96% sulphuric acid) was extruded at a speed of m./min. by means of a conventional T- die process using a 90 mm. extruder, and immediately immersed in a water bath, maintained at 40 C. This provided an average water content for the film of about 3%.
  • the film was then passed through a vessel, in which the atmosphere was maintained at a temperature of 50 C. and a relatively humidity of 60%.
  • the film was then immediately pre-heated to about 75 C. by passing it through a pre-heating zone 1 m. in length at a through-put speed of 10 m./min. where the atmosphere was maintained at 90 C. by conventional infra-red heaters.
  • the pre-heated film was then simultaneously drawn in the longitudinal and transverse directions with a draw speed of about 24,000 percent/ min. through a drawing zone, where the atmosphere was maintained at 150 C. to draw a film with magnification of about 3 in the longitudinal direction and 3,4 in the transverse direction at a ratio of draw speeds of 0.6 to 1.0.
  • the drawn film was heat-set for 10 seconds at 190 C. under tension, in order that its dimensions would be kept constant in a transverse direction, to give a film 1. in thickness.
  • the polyamide film obtained had unevenly reticulated projections on its surface, and a static friction coefficient of 0.7. It had improved antiblocking characteristics and processability.
  • Example 6 Poly-e-caproamide (relative viscosity 3.0 a C. in 96% sulphuric acid) was extruded with a conventional screw extruder having a diameter of 65 mm. to give a raw film density1.l28having a thickness of 215 microns. The raw film was dipped into a water bath, which was maintained at C. to provide an average water content of the film of about 3%. The film was then passed through a vessel, in which the atmosphere was maintained at a temperature of C. and a relative humidity of. and then pre-heated to C. by passing it through a preheating zone 1 m. in length at a through-put speed of 10 m./min. the atmosphere being maintained at C.
  • the preheated film was immediately drawn simultaneously in the longitudinal and transverse directions with a draw speed of about 30,000 percent/min. through a drawing zone, where the atmosphere was maintained at 120 C. by conventional hot air heaters, to draw a film having a magnification of about 3 in both the longitudinal and transverse directions at a ratio of dra-w speeds of 1 to 1.2.
  • the drawn film was heat-set for 10 seconds at 200 C. under tension in order that its dimension in the transverse direction be kept constant to give a film 24 in thickness.
  • the polyamide film obtained had unevenly reticulated fine projections on its surface, and a static friction coefiicient of 1.0 with improved antiblocking characteristics and processability.
  • Example 7 A substantially amorphous film (density 1.128; average thickness of poly-e-caproamide (relative viscosity 3.0 at 25 C. in 96% sulphuric acid) was dipped into a water bath maintained at 35 C. to give a film having an average water content of about 2.5%. The film was pre-heated to about 90 C. for approximately 5 seconds in an atmosphere at 120 C. using conventional infra-red heaters in order to provide a large difference of water content between the surface and the interior of the film.
  • the pre-heated film was immediately drawn simultaneously in the longitudinal and transverse directions with a draw speed of about 30,000 percent/min. through a drawing zone, in which the atmosphere was maintained at 120 C. by conventional hot air heaters, to draw a film Cir having a magnification of about 3 in both the longitudinal and transverse directions at a ratio of draw speeds of 0.9 to 1.2.
  • the draw film was heat-set for 8 seconds at 200 C. under tension in order that its dimensions would be kept constant in a transverse direction to provide a film 15 in thickness.
  • the static friction coefiicient of the polyamide film was 1.2 and it had improved antiblocking characteristics and processability.
  • Example 8 A substantially amorphous film of polyhexamethylene sebacamide (average thicknessdensityl,057) was pretreated with water to give the film a water content of about 3%.
  • the film was preheated to 130 C. by passing through a preheating zone, where the atmosphere was maintained at 180 C.
  • the preheated film was then simultaneously and biaxially drawn in the longitudinal and transverse directions with a draw speed of about 30,000 percent/min. in a drawing zone, where the atmosphere was maintained at 140 C. to draw the film with a magnification of 3 in the longitudinal direction and 3.5 in the transverse direction at a ratio of draw speeds of about 0.6 to 1.0.
  • the drawn film was heat-set by heating for 10 sec. at C. under tension 50 that its transverse dimension would be kept constant whereby to yield a film having a thickness of 15,.
  • the static friction coefficient of the drawn film was about 2.5. It was observed that the obtained film had improved antiblocking characteristics and machinability.
  • a suitable additive may be added to the water absorbed by the film so as to enhance its heat transmision without adverse effect on the film properties.
  • a process for drawing a polyamide film which comprises:
  • polyamide film is selected from a member of the group consisting of poly-e-caproamide, poly-hexamethylene-adipamide, polyhexamethylene sebacamide, poly-l-aminoundecanamide, poly-laurinamide, a copolymerised polyamide or a mixture of two or more thereof.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Polyamides (AREA)
US746889A 1967-07-25 1968-07-23 Process for preparing drawn polyamide films Expired - Lifetime US3560606A (en)

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Application Number Priority Date Filing Date Title
JP4776867 1967-07-25

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US3560606A true US3560606A (en) 1971-02-02

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US (1) US3560606A (enrdf_load_stackoverflow)
BE (1) BE718492A (enrdf_load_stackoverflow)
CH (1) CH480159A (enrdf_load_stackoverflow)
DE (1) DE1779248C3 (enrdf_load_stackoverflow)
FR (1) FR1584032A (enrdf_load_stackoverflow)
GB (1) GB1230599A (enrdf_load_stackoverflow)
NL (1) NL141229B (enrdf_load_stackoverflow)
SE (1) SE359255B (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3788503A (en) * 1969-12-30 1974-01-29 Kohjin Co Method for producing biaxially molecule-oriented poly-{68 -caproamide resin film
US4133802A (en) * 1974-03-26 1979-01-09 Toyo Boseki Kabushiki Kaisha Meta-xylylene diamine/aliphatic dicarboxylic acid polyamide film

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4120928A (en) * 1976-04-19 1978-10-17 Toyo Boseki Kabushiki Kaisha Production of biaxially stretched film of polyamide blend
DE2850182C2 (de) * 1978-11-18 1983-06-23 Naturin-Werk Becker & Co, 6940 Weinheim Schlauchfolie zur Verpackung und Umhüllung von pastösen Lebensmitteln, insbesondere Wurst und Käse

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3788503A (en) * 1969-12-30 1974-01-29 Kohjin Co Method for producing biaxially molecule-oriented poly-{68 -caproamide resin film
US4133802A (en) * 1974-03-26 1979-01-09 Toyo Boseki Kabushiki Kaisha Meta-xylylene diamine/aliphatic dicarboxylic acid polyamide film

Also Published As

Publication number Publication date
GB1230599A (enrdf_load_stackoverflow) 1971-05-05
NL6810318A (enrdf_load_stackoverflow) 1969-01-28
CH480159A (de) 1969-10-31
FR1584032A (enrdf_load_stackoverflow) 1969-12-12
DE1779248C3 (de) 1974-10-31
BE718492A (enrdf_load_stackoverflow) 1969-01-24
SE359255B (enrdf_load_stackoverflow) 1973-08-27
NL141229B (nl) 1974-02-15
DE1779248B2 (de) 1974-03-28
DE1779248A1 (de) 1972-04-20

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