NL8900189A - METHOD FOR MANUFACTURING POLY-EPSILON-CAPROAMIDE FILM - Google Patents

Description

W.

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YOU

V.0. 2005

Process for the production of poly-caproamide film.

The invention relates to a process for the production of homogenized polyamide poly-capro-amide film using a single polymer of caprolactam. The invention particularly relates to a manufacturing method which results in a film of uniform thickness, excellent transparency and low crystallization degree. Poly-f-caproamide polymer with a relative viscosity between 3 and 4.5 is bonded between a high voltage electrode greater than 10 KV and low current cooled by a roller rotary cooler, followed by vertical stretch and stretch horizontally.

This thermoplastic film has improved physical properties such as gas retention, pin-prick resistance, impact resistance, fracture strength, and transparency due to the biaxial (vertical and horizontal) stretching of the unoriented sheet.

Although various methods have been proposed for biaxially stretching unoriented film, they can generally be classified as methods for simultaneous biaxial stretching and methods for sequentially biaxial stretching.

In the simultaneous biaxial stretching method, the wire arrangement of the tension clamp is very complicated since the unoriented film must be simultaneously stretched biaxially (vertically and horizontally) in a tensioner.

This method is very expensive since the device is not yet in common use for this. In addition, this method shows a drop in productivity since the stretching speed is difficult to change.

Fig. 1 shows a manufacturing process in which biaxial stretching is performed sequentially.

Fig. 2 shows a cooling process of the unstretched sheet by the electrostatic pasting method.

89 00 189. " «T * -2-

As shown in Fig. 1, for successively biaxial stretching, use is made successively of a roll-equipped vertical stretching device 3 and a horizontal clamping device 4 of the clamp type, after 5 has extruded an unoriented sheet from the melt through a T-nozzle 1 of a extruder. The sheet is then routinely cooled and cured on the surface of a movable cooler, such as a roll-type rotary cooler 2.

However, the product thus obtained shows poor thermal conductivity in that a thin layer of air is mixed in between the molten, but unstretched sheet, and the movable cooler, thereby obtaining a sheet with a higher degree of crystallization and poor transparency. This is because the molten sheet is quickly cured and crystallized. The stretchability of the unstretched sheet is low, and the transparency of the stretched sheet is also low.

When an unstretched sheet of molten polymer is pasted and cooled on the surface of a cooler without forming a thin layer of air, a sheet of poly-caproamide polymer is obtained with a reduced degree of crystallization and improved stretchability.

According to the invention, to make the extruded molten sheet stick to the surface of the cooler, an electrostatic device is used, which sticks the sheet material to the surface of the cooler and cools it by applying a high voltage at a low current. between the surface of the electrode and the cooler with a knife-shaped, filamentous or multi-needle shaped electrode 5 between the T-nozzle and the cooler or as close as possible to the cooler, with an unstretched sheet passed between them. Rather, use is made of a wire-shaped electrode member rather than an expensive knife-shaped or multi-needle-shaped member.

As for the degree of polymerization of the polyamide resin to be used as the raw material, a relative viscosity of more than 3.0 or more preferably 3.0 to 4.5 is required.

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Homogenized poly-caproamide resin having a degree of polymerization such that the relative viscosity is less than 3.0 readily deteriorates with temperature. Therefore, in film production, the device is contaminated with oligomer and the desired stabilized physical properties of biaxially stretched film are not achieved. When the degree of polymerization is such that the relative viscosity is more than 4.5, it becomes difficult to make films because more load is caused during the manufacturing process.

The invention therefore uses homogenized poly-E-caproamide and, thanks to the electrostatic member described, makes it possible to make a biaxially stretched poly-caproamide film with excellent transparency, uniform thickness, low crystallization degree and low degree of crystallization.

According to the invention, a single polymer of caprolactam, commonly referred to as nylon 6, is used as the raw material. To improve the activity, blocking resistance, stretchability, heat resistance, and electricity removing properties of the stretched polymer film, additives such as active agent, antioxidant, ultraviolet ray absorber and static charge preventant may be added during the polymerization reaction. Blended to such an extent that the nature of the film is not adversely affected.

According to the invention, an unoriented, amorphous stretch sheet is produced by heating the poly-caproamide polymer above its melting point, extruded using an extruder and electrostatically bonded between the surface of a roll rotary cooler and a wire electrode , to which voltage of 4.0-10.0 KV is applied at a low current, and then is cured with cooling. When the voltage is higher than 10.0 KV, sparking takes place. When the voltage is less than 4.0 KV, the productivity of the biaxially stretched polyamide film cannot be achieved because it is 89 00 189.

f «-4- electrostatic power is too low (for biaxially stretched polyamide film, the drawing speed of the unstretched sheet must be greater than 20 m / min to reach production). For the unstretched sheet to be electrostatically pasted, it is desirable that the degree of crystallization is less than 5%, as this facilitates subsequent biaxial stretching.

The described electrostatic member is shown in Fig. 2. A single wire electrode 5 is disposed near the surface of a roll-type rotary cooler 2 and between the electrode 5 and the grounded cooler 2, a high voltage of 4.0-10.0 KV applied at low amperage. Electrostatic power is created between the electrode and the surface of the cooler. When a molten extrudate is passed between them, it is satisfactorily adhered to the surface of the cooler.

Then, as shown in Fig. 1, the unstretched sheet (S) is stretched vertically above its vertical V2 20 stretch value (=) of 2.0 and fed into the clamp type horizontal stretch 4. After the sheet has been pulled out to a certain width and fixed by the heat-fixing part 6, both edges are cut. Thus, a finished film is wound up.

Although such a biaxially stretched poly-cap-caproamide film (F) has satisfactory properties, the film can be stretched vertically or horizontally to improve a particular physical property.

The special value of the film (F) obtained according to the invention is measured as follows: 30 (A)% thickness deviation = ~ dmin x 100 agem in which: d x = the maximum thickness in the width direction; d. = the minimum thickness in the width direction; mm dgem = the average thickness in the width direction.

8900189.

% -ir -5- (B) relative viscosity: the resin is dissolved in 96.3% sulfuric acid at a concentration of 1.0 g / 100 ml and measured in a thermostat of 20 ° C with a 5 Oswald viscometer.

Embodiments 1-6

Homogenized polyamide poly-i-caproamide resin with a relative viscosity between 2.0 and 4.5 is dried in a rotary vacuum dryer at 110 ° C. After the moisture content has been brought to 0.1 wt%, the resin is melted at 260 ° C in a 90 mm diameter extruder equipped with a T-nozzle 1. Molten polymer resin is extruded between a ground-cooled rotary cooler 2 cooled at 25 ° C and a wire-shaped electrode 5 between which a voltage of 5.0 KV is applied at a low amperage. The polymer resin is pressed onto the cooler and an amorphous unstretched sheet (S) having a thickness of about 150 yam and a width of 1 m is obtained. This unstretched sheet (S) is stretched vertically in a stretch ratio, which is three times more is then a normal vertical stretcher (3) and then horizontally stretched in a ratio 3.5 times more than a normal clamp type horizontal stretcher. When its heat is adjusted, a biaxially stretched film (S) is wound with a thickness of 15 µm.

Table A shows the stretchability of each film produced. The percentage thickness deviation of each stretched film depends on its relative viscosity. In embodiments 1-6, the applied voltage is 5.0 KV and 30 the draw speed of the roll rotary cooler is 20 or 40 m / min.

Table A shows that a relative viscosity of 3.0-4.5 provided satisfactory stretchability at a thickness deviation of less than 10%.

8900189.

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TABLE A

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Drying, electrostatic bonding and stretching conditions are the same as in Table A. From homogenized polyamide poly-caproamide resin with a relative viscosity of 3.5, an unstretched sheet and a stretched film are obtained at an adhesive stress of 3 .0-10.0 KV and a drawing speed of the roll-shaped rotary cooler of 5-70m / min. The degree of adhesion of the molten polymer resin to the surface of the roll-shaped rotary cooler determines the thickness deviation, the stretchability of the 10 stretched sheet and the thickness deviation of the stretched film.

Table B shows the drawing speed of the unstretched sheet of more than 20 m / min within the limits of 4.0-10.0 KV, as well as improved stretchability and a thickness deviation of the stretched film of less than 10%.

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The invention provides a very effective method of manufacturing biaxially stretched polycaproamide film with a uniform thickness, excellent transparency and low crystallization degree. The degree of crystallization is reduced by fixing the homogenized polyamine poly-caproamide sheet obtained from a single-caprolactam polymer with a relative viscosity of at least 3.0, preferably 3.0-4.5. The degree of polymerization is fixed by the electrostatic bonding method, with a voltage of 4.0-10.0 KV at a low amperage bonding the resin material between the surface of a rotary rotary cooler and a filamentary electrode.

89 00189.

Claims (1)

A method of manufacturing a normal polymer film, wherein an unstretched sheet is produced by cooling and curing extruded molten resin on a roll-type rotary cooler and the unstretched sheet is vertically stretched with a vertical stretcher and then horizontally stretched with a horizontal stretcher, characterized in that a sheet with a low crystallization degree and a small deviation from the degree of crystallization is produced from an electrostatic sticking method from cap-caproamide polymer with a relative viscosity of 3.0-4.5 a voltage of 4.0-10.0 KV is applied to a filamentary electrode arranged near the surface of the roller-shaped rotary cooler, after which the obtained sheet is successively biaxially stretched to form a film. 8900189.