KR20060078280A - Resin composition for biaxial oriented polyamide film, method of producing biaxial oriented polyamide film, and biaxial oriented polyamide film formed by the method - Google Patents

Abstract

The present invention provides a resin composition for a biaxially stretched polyamide film comprising a polyamide resin and 50 to 500 ppm (based on the weight of polyamide resin) of N, N'-ethylene bisamide, and a single polymerization or copolymerization of lactams, followed by melt extrusion. And then biaxially stretched to produce a polyamide film, biaxially stretched polyamide in which 50 to 500 ppm of N, N'-ethylenebisamide is added to the polyamide resin in the single polymerization stage or just before melt extrusion. The manufacturing method of a film, and the biaxially stretched polyamide film manufactured by the said method are related.

According to the present invention, when the polyamide resin and EBS are copolymerized or the polyamide resin is blended with EBS immediately before melt extrusion, the film is extruded and then biaxially stretched to produce a film, the bowing phenomenon of the film is improved and the film is improved. The uniformity of the quality is improved.

Polyamide Composition, Biaxially Stretched Polyamide Film, Ethylene Bisamide

Description

RESIN COMPOSITION FOR BIAXIAL ORIENTED POLYAMIDE FILM, METHOD OF PRODUCING BIAXIAL ORIENTED POLYAMIDE FILM, AND BIAXIAL ORIENTED POLYAMIDE FILM FORMED BY THE METHOD}

This invention relates to the resin composition for biaxially stretched polyamide films, the manufacturing method of a biaxially stretched polyamide film, and the biaxially stretched polyamide film manufactured by this method. More specifically, by adding ethylene-bis-stearamide (hereinafter abbreviated as "EBS") during polymerization or extrusion to improve the film's bowing phenomenon, it is possible to improve the film quality uniformity and printing, etc. It relates to a resin composition for a biaxially stretched polyamide film capable of improving post-processability, a method for producing a biaxially stretched polyamide film, and a biaxially stretched polyamide film produced by this method.

Polyamides, which are conventionally represented by polyamide 6 (hereinafter abbreviated as "NY6"), have excellent physical and chemical properties and are widely used in fibers and films. In particular, the NY6 film has excellent transparency and strength, as well as excellent gas barrier properties, and is used as a base film for various packaging films.

If the physical properties of the film, for example, the mechanical strength and density are nonuniform in each width direction, defects such as distortion of the surface of the film may occur in post-processing such as coating, deposition, cutting, and printing, thereby degrading the quality of the finished product. . On the other hand, if the uniformity of the widthwise portions allowed in the post-processing of the film is satisfied, there is a problem that the yield of the film is lowered. Therefore, it was desired to produce a film having uniform physical properties for each widthwise portion without lowering the product yield.

However, in the conventional manufacturing method, since the clips hold both ends of the film in the transverse stretching machine, the longitudinal residual stress generated during the longitudinal stretching and the transverse residual stress generated during the transverse stretching, and the shrinkage caused by heat setting The stress is constrained at the end of the film with respect to stress, while the central portion of the film is less influenced by the clip, so the restraint against deformation is relatively weak. Therefore, the bowing phenomenon of the film caused by the difference in the restraint force between the both ends and the center part in the transverse stretching machine in the direction opposite to the direction in which the film travels is accompanied by the process of biaxial stretching and heat setting. Although it becomes an unavoidable problem in the process, it is extremely difficult to equalize the widthwise physical properties of the film due to the bowing phenomenon of the film.

In order to obtain uniform film properties in the transverse direction, various methods have been tried in the process and equipment.

For example, Japanese Patent Publication No. 64-2914 discloses a method of heat treatment using a heating roll. There is a disadvantage in that both ends are not thermally constrained by a heating roll to cause width shrinkage, and Japanese Patent Publication No. 67-9273 performs heat treatment using a temperature gradient in the transverse direction of the film, and Japanese Patent Application Laid-Open No. 87-87. 183327 and 87-183328 disclose heat treatment processes such as changes in wind speed and air volume and forced heating at both ends of the film, but such heat treatment methods reduce the effective operation rate due to the complexity of equipment and prolongation of condition adjustment time. There were the same disadvantages.

In addition, Japanese Patent Publication No. 88-24456 discloses a method of forcibly advancing the center portion of the film by a nip roll, but all of these methods have a problem that the film is damaged by contact with the roll at a high temperature.

On the other hand, Japanese Patent Laid-Open Publication Nos. 91-130126, 91-130127, 92-142916, and 92-142917 disclose a heat treatment method for adding a cooling process after a lateral stretching process. Although the cooling treatment is performed in the section, there is little effect of reducing the bowing phenomenon of the film, and there is a disadvantage in that productivity decreases due to an increase in equipment cost and waste of energy.

On the other hand, although a method of adding (Ethylene-bis-stearamide, abbreviated as "EBS") as an organic slip agent and a water-repellent agent (Japanese Patent Laid-Open No. 49-90346, US Patent 4490324) is disclosed, Boeing phenomenon It is not described at all, and it is described that it is added at only 500ppm or more. If it is added in such a content, there is no effect of improving Boeing, but rather, the Boeing phenomenon is worsened. ) In the form of. In addition, the heat treatment temperature was also limited to 40 to 150 ℃, there was a distance from the film production of NY6.                         

The present inventors have completed the present invention by finding out that when the film is prepared by adding EBS, which functions as an organic slip agent and a water repellent agent, to NY6 resin during extrusion, the film can be improved. It came to the following.

An object of the present invention is to improve the bowing phenomenon of a film by adding ethylene-bis-steaamide to form a film during polyamide polymerization or extrusion of a polyamide resin, thereby improving film uniformity and post-processing of films such as printing. The resin composition for biaxially stretched polyamide films which can be made, the manufacturing method of a biaxially stretched polyamide film, and the biaxially stretched polyamide film manufactured by this method are provided.

In order to achieve the above technical problem, in one embodiment of the present invention, a polyamide resin; And it provides a resin composition for biaxially stretched polyamide film comprising 50 to 500ppm of N, N'-ethylenebisamide of the formula (1) based on the weight of the polyamide resin.

[Formula 1]

(Wherein R ₁ and R ₂ are C14-C22 aliphatic hydrocarbon chains.)

According to an embodiment of the composition of the present invention, the N, N'-ethylenebisamide may be N, N'-ethylenebisstearamide or N, N'-ethylenebisoleamide.

In yet another aspect of the present invention, a method for producing a polyamide film by homopolymerizing or copolymerizing lactams, melt extruding and then biaxially stretching the polyamide film in the monopolymerization or copolymerization step or immediately before melt extrusion. There is provided a method for producing a biaxially stretched polyamide film in which 50 to 500 ppm of N, N'-ethylenebisamide of the following formula (1) is added to an amide resin.

According to one embodiment of the method for producing a film of the present invention, the melt extrusion may be carried out at a temperature of 240 to 265 ℃.

According to another embodiment of the manufacturing method of the film of the present invention, the lactam may be ε-caprolactam (abbreviated as "CPL").

In still another aspect of the present invention, there is provided a biaxially stretched polyamide film formed by the method for producing the biaxially stretched polyamide film.

According to one embodiment of the polyamide film of the present invention, the baud rate may be 2.5 to 3.00, and the specific gravity change may be 0.01 to 0.10.

Hereinafter, the present invention will be described in detail.

The polyamide resins used in the present invention are homopolyamides or copolyamides obtained by polymerizing or copolymerizing lactams using water as a reaction initiator, and, if necessary, metal acetate and heat for improving electrostatic pinning properties. You may polymerize or copolymerize further using additives, such as a phosphorus compound for stability, and silica inorganic particle for giving unevenness | corrugation to a film surface.

The lactams are any one selected from the group consisting of ε-caprolactam, capryllactam, lauryllactam, α-pyrrolidone and α-piperidone. Among these, epsilon -caprolactam is preferable from the viewpoint of supply and availability of raw materials. The lactams may be homopolymerized or copolymerized with other monomers, and other copolymerizable monomers include nylon salts composed of aliphatic or aromatic diamines and aliphatic or aromatic dicarboxylic acids, and representative examples of the diamines are ethylene. Diamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylenediamine, hexylenediamine, paraxylylenediamine, and the like. Terephthalic acid, isophthalic acid, decamethylenecarboxylic acid, dodecamethylenecarboxylic acid, pimeric acid and the like.

The polyamide resin used in the present invention is blended with 50 to 500 ppm of EBS immediately before melt extrusion of a polyamide resin produced by a conventionally known melt polycondensation method, or after adding 50 to 500 ppm of EBS to lactams. It is resin formed by superposition | polymerization or copolymerization by a well-known melt polycondensation method. The polyamide resin preferably has a relative viscosity of 2.7 to 3.5 measured using a sulfuric acid (96%) solvent at 25 ° C in view of excellent film formability.

At this time, if the amount of melt polycondensation or blending EBS is less than 50ppm, there is no effect of Boeing improvement, and if the amount of EBS is more than 500ppm, the Boeing phenomenon is rather deteriorated and the physical properties of the final film are worsened.

Thereafter, the polyamide resin was formed into a chip form using a twin screw extruder or the like, and then the polyamide resin in the chip form was melt-extruded by a conventionally known T-die method to obtain an unstretched sheet. It is possible to prepare a biaxially stretched polyamide film by stretching to about 2.6 to 3.3 times in the machine direction and then to 3.0 to 4.1 times in the direction perpendicular to the machine direction. In the melt extrusion process by the extruder, the temperature of the melted kneaded product is preferably maintained at 240 to 265 ° C. If the temperature exceeds 265 ° C, the moldability at the time of stretching is poor, the color of EBS is decomposed by heat, and the color is degraded, and the impact strength of the produced biaxially oriented polyamide film is lowered. There is a problem that film molding becomes difficult.

In the step of biaxial stretching by the tenter method, the heat treatment is preferably performed at a temperature in the range of 190 to 215 ° C, and the heat treatment time is preferably 1 second or more. If less than 1 second, heat setting tends to be insufficient. In addition, the upper limit of the heat treatment time is not particularly limited, but the longer the treatment time, the larger the stretching apparatus is required and the higher the cost. Therefore, the heat treatment time is preferably about 1 to 30 seconds. The relaxation rate of the film in heat processing is set to 10% or less (MD direction and / or TD direction). When the film is heat-treated in a state of slightly relaxed, the degree of crystallinity of the film is increased and the shrinkage rate is lowered. As a result, a film excellent in dimensional stability is obtained.

The bowing ratio of the biaxially stretched polyamide film prepared according to the present invention is preferably 2.5 to 3.00 because the difference in physical properties between the center and the edge is minimized.

In addition, the specific gravity change rate in the width direction of the biaxially stretched polyamide film prepared according to the present invention is preferably 0.01 to 0.10, since the difference in physical properties between the center and the edge part is minimized.

And the additive can be suitably added to the biaxially stretched polyamide film which concerns on this invention as needed. Examples of the additive that can be used include antiblocking agents such as inorganic fillers and lubricants such as calcium stearate. In addition, the biaxially stretched polyamide film according to the present invention can be laminated with other films.

Hereinafter, the present invention will be described in more detail with reference to the following Examples, which are intended to illustrate the present invention, but the scope of the present invention is not limited by the following Examples.

In the following examples, only the evaluation of the bowing rate, the change in specific gravity direction in the width direction, the degree of orientation for each film position, and the number of film breaks were performed. Instead.

Boeing rate

For the shape in which the straight line drawn transversely on the surface of the film from the entrance of the transverse drawer exits the transverse drawer and then bent into a bow, the distance from the reference straight line to the peak of the bow (mm) is b. And when the width (mm) of the film F is W, it calculated and calculated | required by the following formula | equation.

B = b / W × 100 (%)

Rate of specific gravity change by width part

Five points were taken at uniform intervals in the width direction of the film, and the specific gravity was first determined according to the conditions of ASTM D1505 by the density gradient pipe method, and then calculated by the following equation.

Orientation by Film Location

The left, middle, and right three points were taken in the width direction of the film, and the orientation angles for each position of the film were measured using an orientation angle measuring device called a cobra.

Film breaks

In the production of a film for 12 hours in a continuous process in which an unstretched sheet is produced by a conventional method, and the unstretched sheet is stretched 2.8 times in the machine direction and 3.5 times in the direction perpendicular to the machine direction. The number of breaks was measured.

<Examples 1-3>

Water, hypophosphorous acid, magnesium acetate and silica were added as additives to the CPL, and EBS was blended to a NY6 resin having a relative viscosity of 3.0 by the conventional melt polycondensation method, and melt-extruded to prepare a film. The bowing rate of the film, the specific gravity change rate in the width direction of the film, the degree of orientation for each film position, and the number of film breaks were measured. The results are shown in Table 1.

<Examples 4-6>

Boeing rate of the film while melting and extruding NY6 resin having a relative viscosity of 3.0, prepared by the conventional melt polycondensation method, by adding water, hypophosphorous acid, magnesium acetate, silica, and EBS in Table 1 as additives to the CPL. , The widthwise specific gravity change rate of the film, the degree of orientation for each film position, and the number of film breaks were measured. The results are shown in Table 1.

Comparative Example 1

Except not blending EBS, the film was prepared in the same manner as in Examples 1 to 3 while measuring the bowing rate of the film, the specific gravity change rate in the width direction of the film, the degree of orientation for each film position and the number of film breaks. The results are shown in Table 1.

<Comparative Example 2-4>                     

Except for blending the EBS to the content of Table 1, while measuring the film in the same manner as in Examples 1 to 3, the film boeing rate, the specific gravity change rate in the width direction of the film, the degree of orientation by film position and the number of film breaks were measured. The results are shown in Table 1.

<Comparative Example 5-7>

Except for copolymerizing using EBS in the content of Table 1, while measuring the film in the same manner as in Examples 4-6, measuring the boeing rate of the film, the specific gravity change rate in the width direction of the film, the degree of orientation by film position and the number of film breaks It was. The results are shown in Table 1.

TABLE 1

EBS (ppm) Boeing rate (%) % Change in specific gravity Orientation Angle by Film Position (°) Breaks Left medium Ooh Example 1 100 2.95 0.04 85 88 87 0 Example 2 250 2.79 0.04 85 87 86 0 Example 3 450 2.93 0.05 84 86 84 0 Example 4 100 2.68 0.04 84 87 85 0 Example 5 250 2.65 0.06 85 87 84 0 Example 6 450 2.95 0.05 85 89 86 0 Comparative Example 1 0 4.64 0.16 83 92 84 One Comparative Example 2 1000 4.25 0.13 84 90 81 2 Comparative Example 3 2000 3.64 0.10 86 89 84 2 Comparative Example 4 3000 3.97 0.13 85 89 84 One Comparative Example 5 1000 4.57 0.12 82 90 84 2 Comparative Example 6 2000 3.78 0.17 83 88 82 One Comparative Example 7 3000 4.02 0.16 84 87 81 2

As shown in Table 1, the biaxially stretched polyamide film produced according to the present invention can be seen that the film quality is uniform due to the small boeing rate and specific gravity change rate, and also excellent in workability because no breakage occurs during manufacturing. Able to know.

 According to the present invention, the film is formed by adding ethylene-bis-steaamide during polyamide polymerization or during extrusion of polyamide resin to improve the bowing phenomenon of the film, thereby making biaxial stretching excellent in small widthwise physical properties and excellent post-processing property. Polyamide films can be obtained.

Claims (7)

Polyamide resins; And 50 to 500 ppm of N, N'-ethylenebisamide of Chemical Formula 1 based on the weight of the polyamide resin. [Formula 1]

(Wherein R ₁ and R ₂ are C14-C22 aliphatic hydrocarbon chains.) The method of claim 1, The N, N'-ethylene bisamide is N, N'-ethylene bis stearamide or N, N'-ethylene bis oleamide resin composition for biaxially stretched polyamide film. In the method of producing a polyamide film by homopolymerizing or copolymerizing lactams, melt extrusion and then biaxial stretching Method for producing a biaxially stretched polyamide film, characterized in that 50 to 500ppm of N, N'-ethylene bisamide of the general formula (1) is added to the polyamide resin in the single polymerization or copolymerization step, or just before melt extrusion . The method for producing a biaxially stretched polyamide film according to claim 3, wherein the melt extrusion is performed at a temperature of 240 to 265 ° C. The method of claim 3, wherein The said lactam is epsilon caprolactam, The manufacturing method of the biaxially-stretched polyamide film characterized by the above-mentioned. Biaxially stretched polyamide film produced by the process according to claim 3. The method of claim 6, A biaxially stretched polyamide film, having a bowing rate of 2.5 to 3.00 and a specific gravity change rate of 0.01 to 0.10.