JP2545462B2 - Biaxially oriented polyamide film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention comprises an aliphatic polyamide mainly composed of polytetramethylene adipamide and a mixture thereof with an aromatic poiamide mainly composed of polymethaxylylene adipamide, The present invention relates to a biaxially oriented polyamide film having heat resistance, gas barrier properties and mechanical strength.

[Prior Art] Polytetramethylene adipamide is produced from tetramethylene diamine or its functional derivative and adipic acid or its functional derivative, and is known as nylon 46 resin.

This nylon 46 resin is considered to be of great value as a useful engineering plastic because it has excellent mechanical strength such as tensile strength, bending strength, impact strength, etc., and also excellent heat resistance and sliding characteristics. There is.

The reason why Nylon 46 resin shows these excellent properties is that its melting point and crystallinity are extremely high when compared with general polyamide resins such as Nylon 66 resin, Nylon 6 resin, Nylon 12 resin. However, this also causes the nylon 46 resin to have significantly poorer extrusion moldability than general polyamide resins.

In other words, the fact that nylon 46 resin has a high melting point of approximately 290 ° C means that the resin temperature during extrusion film formation must be 300 ° C or higher, which is the thermal decomposition temperature of the amide bond (approximately 320 ° C). It will be close. In other words, nylon 4
6 The extrusion film-forming temperature of resin causes a drawback that the temperature range suitable for extrusion film-forming is narrow due to its melt fluidity and conditions for avoiding thermal decomposition. Also, having high crystallinity means that more heat is required to melt the nylon 46 resin. This means that a high plasticizing temperature, a long plasticizing time, a high kneading torque, etc. are required during extrusion film formation, which not only cause high cost in equipment and production, but also stable. Extrusion film formation cannot be performed, and technical problems such as inducing thermal decomposition of the polymer occur.

Furthermore, when trying to biaxially stretch an unstretched film obtained by extrusion, uniaxial stretching is easy because the crystallinity of the unstretched film is high, but biaxial stretching is difficult. Defects such as cutting, stretching unevenness, and pinholes tend to occur not only in mechanical drawing methods such as sequential drawing and simultaneous drawing but also in inflation methods that use gas, and defects such as pinholes with good thickness unevenness tend to occur. It is extremely difficult to obtain a biaxially oriented film that is free of defects.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to improve the defects while maintaining the excellent properties of nylon 46 resin, and to provide a good unstretched film in melt extrusion. Another object of the present invention is to provide a technique that enables biaxial orientation.

[Structure of the Invention] As a result of earnest research to improve extrusion and biaxially stretched film-forming property of nylon 46 resin, the present inventor has blended polytetramethylene adipamide with a specific amount of polymeta-xylylene adipamide. When used with polyamide, it has excellent extrusion and biaxially stretched film forming properties and excellent heat resistance that is the same as that of nylon 46 resin alone, and gas barrier that is the same as that of polymethyxylylene adipamide alone. The present invention has been accomplished by the finding that it exhibits excellent properties and also has good mechanical properties.

Here, polymeta-xylylene adipamide is made from meta-xylylenediamine or a functional derivative thereof and adipic acid or a functional derivative thereof, and has long been known as a nylon MXD6 resin.

This nylon MXD6 resin can be biaxially stretched, and the characteristic of the biaxially oriented film is that it has excellent gas barrier properties, and also has excellent mechanical strength such as tensile strength and secondary processability. It is used for a wide range of purposes at the beginning.

The reason why the nylon MXD6 resin exhibits excellent biaxial stretchability is that it has appropriate crystallinity.

The present invention is polytetramethylene adipamide 30 to 90% by weight.
Is a biaxially oriented polyamide film comprising a mixture of 70 to 10% by weight of polymethaxylylene adipamide.

 The present invention will be described in detail below.

In the present invention, polytetramethylene adipamide and adipic acid or a functional derivative thereof as an acid component,
The main object is a polyamide obtained by a condensation reaction using tetramethylenediamine or a functional derivative thereof as an amine component, but a part of the adipic acid component or tetramethylenediamine component may be replaced with another copolymerization component. . Such polytetramethylene adipamide is also called nylon 46 resin.

A preferred embodiment of the method for producing nylon 46 resin is disclosed in
It is described in JP-A-149430 and JP-A-56-149431.

The intrinsic viscosity of the nylon 46 resin used in the present invention is m-
When measured with cresol at 35 ° C., it is preferably in the range of 0.80 to 1.90, more preferably 1.00 to 1.60.

When using nylon 46 resin having an intrinsic viscosity of more than 1.90, the fluidity of the composition is poor, the gloss of the appearance of the obtained molded product is lost, and the variation in its mechanical and thermal properties becomes large. Not preferable.

On the other hand, if the intrinsic viscosity is less than 0.80, the mechanical strength of the composition will be low.

In the present invention, polymeta-xylylene adipamide mainly uses a polyamide obtained by a condensation reaction using adipic acid or a functional derivative thereof as an acid component and meta-xylylenediamine or a functional derivative thereof as an amine component. A part of the adipic acid component or the metaxylylenediamine component may be replaced with another copolymerization component.

The polymethaxylylene adipamide is a polyamide structural unit obtained from metaxylylenediamine and at least one α, ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain of at least 50 mol% or more, preferably It is a copolymer containing 70 mol% or more. Examples of these include homopolymers such as polymeta-xylylene adipamide, polymeta-xylylene sebacamide, poly-meta-xylylene speramide, and meta-xylylene / para-xylylene adipamide copolymers, meta-xylylene / para-xylylene pimeramide. Copolymers, copolymers such as metaxylylene / paraxylyleneazeramide copolymers, etc., and components of these homopolymers or copolymers with aliphatic diamines such as hexamethylenediamine and alicyclic diamines such as piperazine , Para
Aromatic diamines such as bis-2-aminoethylbenzene, aromatic carboxylic acids such as terephthalic acid, lactams such as ω-caprolactam, ω-aminenocarboxylic acids such as 7-aminoheptanoic acid, and para-aminomethylbenzoic acid. Examples thereof include a copolymer obtained by copolymerizing with an aromatic aminocarboxylic acid. The metaxylylenediamine component of the polymetaxylylene adipamide used in the present invention may contain metaxylylenediamine or 30 mol% or less of para-xylylenediamine. Further, the constitutional unit obtained from the cysylylenediamine component and one or more kinds of α, ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms is at least 50 mol% or more, preferably 70 mol% or more in the molecular chain. Is preferable from the viewpoint of moldability.

The polymeta-xylylene adipamide in the present invention is required to have a high viscosity such that a uniform film is formed during melt molding, and a relative viscosity of 1.8 to 4.0.
Is preferred.

Polymeta-xylene adipamide was prepared by the usual melt polymerization method.
It can be obtained by a method of carrying out polymerization at a temperature of about 0 to 300 ° C. under normal pressure, increased pressure or reduced pressure.

In the present invention, the mixing ratio of polymethaxylylene adipamide to polytetramethylene adipamide is 10% by weight to 70% by weight, preferably 10% by weight to 50% by weight, based on the weight of the mixture.
%, More preferably 20 to 50% by weight.

If the compounding amount of polymethaxylylene adipamide exceeds 70% by weight, the heat resistance will decrease. If it is less than 10% by weight, the gas barrier property based on polymethaxylylene adipamide will only decrease. Therefore, the effect of improving the extrusion property and the biaxially stretched film forming property of polytetramethylene adipamide becomes insufficient, and the film forming becomes extremely difficult.

If desired, the biaxially oriented film of the present invention may contain a pigment and other compounding agents in an expression amount. These compounding agents should be compounded within a range that does not lose the small amount of effect expression by addition, the excellent characteristics inherent to the composition by excessive addition, and the advantage in film formation.

As such a compounding agent, a flame retardant, for example, a brominated biphenyl ether, a brominated bisphenol-A diglycidyl ether and its oligomer, a halogen-containing compound such as a polycarbonate oligomer produced from brominated bisphenol-A as a raw material; Phosphorus compounds such as phenyl phosphate; Phosphorus-nitrogen compounds such as phosphonamide; Flame retardant aids such as antimony trioxide and zinc borate can be added. In addition, hindered phenol compounds for the purpose of improving heat resistance. It is also possible to add an antioxidant or a heat stabilizer such as an organic phosphorus compound or a sulfur compound. Various epoxy compounds may be added for the purpose of improving melt viscosity stability and hydrolysis resistance. Examples of the epoxy compound include a bisphenol A type epoxy compound obtained by reacting bisphenol A with epichlorohydrin, an aliphatic glycidyl ether formed by a reaction of various glycols or glycerol with epichlorohydrin, a novolak type epoxy compound, an aromatic or aliphatic carboxylic acid. Type epoxy compound,
Alicyclic compound type epoxy compounds obtained from alicyclic compounds are preferable, and particularly preferable epoxy compounds include bisphenol A type epoxy compounds and low molecular weight polyethylene glycol diglycidyl ether.

Other stabilizers, colorants, antioxidants, lubricants, UV absorbers, and antistatic agents can also be added.

Preferred lubricants include calcium carbonate, silicon dioxide (including hydrates, diatomaceous earth, silica sand, quartz, etc.),
Alumina, silicate containing 30% by weight or more of SiO ₂ [eg, amorphous or crystalline clay minerals, aluminosilicate compounds (including calcined products and hydrates), warm asbestos, zircon, fly ash, etc.] , Oxides of Ma, Zn, Zr and Ti, sulfates of Ca and Ba, phosphates of Li, Na and Ca (including monohydrogen and dihydrogen salts), benzoates of Li, Na and K, Mg, Ca, Ba, Zn, Cd, Pb, Sr, Mn, Fe, Co and Ni titanates, Ba and Pb chromates, carbon (eg carbon black, graphite etc.), glass (eg glass powder, Glass beads, etc.), MgCO ₃ , fluorite,
And ZnS are exemplified. Particularly preferred are spherical silica, silicone resin particles, silicic acid anhydride, hydrous silicic acid, aluminum oxide, aluminum silicate (calcined product,
(Including hydrates), 1 lithium phosphate, 3 lithium phosphate,
Sodium phosphate, calcium phosphate, barium sulfate, titanium oxide, lithium benzoate, double salts of these compounds (including hydrates), glass powder, clay (including kaolin, bentonite, clay etc.), talc, diatomaceous earth Etc. are illustrated.

A small amount of other thermoplastic resin such as styrene resin, acrylic resin, polyethylene, polypropylene, fluororesin, other polyamide resin, polycarbonate resin, polysulfone, etc .; thermosetting resin such as phenol resin, melamine resin, unsaturated Polyester resin, silicone resin and the like; further soft thermoplastic resin such as ethylene-vinyl acetate copolymer, polyester elastomer,
Ethylene-propylene-terpolymer or the like may be added.

Any compounding method can be used to obtain the biaxially oriented film of the present invention.

Usually, it is preferable to disperse these compounding components more uniformly, and to homogenize them by mixing all or part of them simultaneously or separately, for example, with a mixer such as a blender, kneader, roll, or extruder. A method may be used in which some of the components are mixed simultaneously or separately, for example, by a blender, a kneader, a roll, an extruder, etc., and the remaining components are mixed by these mixers or extruders to homogenize them. . Further, there is a method in which a composition dry-blended in advance is melt-kneaded in a heated extruder to homogenize it, then extruded into a wire shape, and then cut into a desired length to granulate. The film-forming composition thus produced is usually kept in a sufficiently dried state, put into a film-forming machine hopper, and provided for film formation. Further, it is also possible to dry-blend the constituent raw materials of the composition and directly put them in the hopper of the film-forming machine and melt-knead them in the film-forming machine.

When melt-kneading or melt-extruding the polymer mixture of the present invention, it is desirable that the residence time in the molten state does not exceed 5 minutes.

When the residence time exceeds 5 minutes, deterioration of the resin due to thermal decomposition of amide bond due to high melting temperature and deterioration of heat resistance of nylon 46 resin due to progress of amide exchange reaction are observed.

From the above lack of thermal stability, the performance of maintaining heat resistance based on the nylon 46 resin recognized in the present invention,
It is unique to this polymer mixture, and it is clear that it is difficult to maintain or improve heat resistance by copolymerization.

In order to obtain a polyamide biaxially stretched film comprising the polymer mixture of the present invention, the polymer mixture is heated to 290 ° C to 3 ° C.
Melts in the temperature range of 10 ° C, preferably 290 ° C to 300 ° C,
The film is extruded from a flat die such as a T-die or an I-die into a film shape, and is rapidly cooled by contacting it with a roll cooled to a temperature not higher than the glass transition point of the unstretched film, preferably 25 ° C to 60 ° C. , A substantially amorphous unstretched film is obtained. At this time, if the temperature of the roll is higher than the glass transition point of the polymer mixture, a flat film cannot be obtained or devitrification occurs, which makes uniform stretching difficult in the next stretching step.

In order to biaxially stretch an unstretched film, the film is stretched between two or more rolls having different peripheral speeds in the machine direction so as to have a stretching ratio of 2 to 5 times, and then both ends of the film are gripped with clips. A method of stretching in the transverse direction at right angles to the stretching direction in the first stage is usually used, but the order may be reversed and transverse stretching may be carried out, followed by longitudinal stretching.

The stretching condition for the first stage is a glass transition temperature of the film material of 150 ° C., preferably 80 ° C. to 130 ° C.
Stretching is performed at a draw ratio of 2 times, preferably 3 to 4 times. When the stretching temperature of the film is lower than the glass transition point of the film, extremely high stress is required to stretch the film, and the film often breaks or devitrifies, which makes high-stretching difficult. On the other hand, when the film is stretched at a temperature higher than 150 ° C., the film is fused and the film having an effective orientation cannot be obtained.

Next, when the film oriented in one direction is stretched in a direction substantially perpendicular to the stretching direction, the film is at a temperature higher than the stretching temperature and a temperature of 150 ° C. or lower, preferably 80 ° C. to 130 ° C. Stretching is performed at a temperature of 2 to 5 times, preferably 2.5 to 4 times. When the stretching temperature is equal to or lower than the above temperature, it becomes difficult to uniformly stretch the film in the direction perpendicular to the orientation direction against the orientation and crystallization already formed in the film, and in addition, Thickness unevenness becomes large. On the other hand, when the stretching temperature is higher than the melting point of the film of -5 [deg.] C. or lower, the orientation of the film already formed is destroyed, and it becomes difficult to obtain a film having excellent physical properties. If the film has a draw ratio of less than 2 times, the film is likely to have unevenness of drawing and uneven thickness, and it is difficult to impart sufficient orientation to the film. Further, if the stretching ratio exceeds 5 times in the first stage stretching, the next stretching becomes difficult or breaks, but the second stage stretching easily causes the film to break.

The biaxially stretched polyamide film thus obtained exhibits good properties as it is, but it may be further stretched in the machine direction or the transverse direction in order to improve the physical properties in a specific direction. In order to further impart thermal stability to the stretched film, the film may be stretched at a temperature of 275 ° C. or higher and 275 ° C. or lower for 5 minutes or less, preferably 5 to 30.
Heat treat for seconds. During the heat treatment, the film is held in either a fixed length, relaxed or stretched condition, or a combination thereof. This heat treatment increases the crystallization of the film, removes the strain of the film generated during the stretching process, and improves the mechanical properties and dimensional stability of the film.

The biaxially stretched polyamide film obtained as described above has characteristics such as excellent mechanical strength, heat resistance, and gas barrier property, although the characteristics vary depending on the composition of the polyamide mixture and the film forming conditions.

In the present invention, as the biaxial stretching method, the above-mentioned sequential biaxial stretching method, simultaneous biaxial stretching method, or bubble-blow stretching of an unstretched film obtained by extruding from a circular die and contacting a mandrel and rapidly cooling. Any method such as an inflation method in which simultaneous biaxial stretching is performed to obtain a tubular film may be used.

Hereinafter, the present invention will be described more specifically with reference to examples.

 The measurement items in the examples were measured by the following methods.

(1) Relative viscosity (ηrel) 0.1% by weight in 96% sulfuric acid measured at 20 ° C. (2) Intrinsic viscosity ([η]) measured at 25 ° C. using m-cresol solvent (3) Oxygen gas permeation coefficient ( Po ₂ ) and carbon dioxide permeation coefficient (Pco ₂ ) O ₂ / with a GPM-200 type gas permeation meter manufactured by Lyssy of Switzerland
Oxygen gas permeation amount and carbon dioxide gas permeation amount were measured at 30 ° C using a mixed gas of CO ₂ = 80/20 (volume).
It is set to 00 mm and pulled at a tensile speed of 100 mm / min and a chart speed of 100 mm / min with an Instron type universal tensile tester, and the Young's modulus is calculated from the tangent line of the rising portion of the obtained load-elongation curve.

(5) Breaking strength and breaking elongation From the stress-strain curve obtained by the method of (4), the strength at the breaking point,
Find the elongation.

Examples 1-5 Intrinsic viscosity 1.67 dried at 105 ° C. under reduced pressure of 10 Torr for 12 hours
Nylon 46 resin ("STANYL" made by DSM, Netherlands)
And nylon MXD6 resin (“MX Nylon 6007” manufactured by Mitsubishi Gas Chemical Co., Inc.) dried under the same conditions as above were uniformly mixed in advance with a tumbler in an amount ratio shown in Table 1, and then the screw diameter was 68 mm. Cylinder temperature 305 using a vented extruder or Labo Plastomill twin screw extruder
Melt-kneading was performed at 0 ° C., and threads discharged from the die were cooled and cut to obtain molding pellets.

Then, the pellets were melted at 300 ° C and extruded from a T-die on a cooling roll kept at 60 ° C to a thickness of 220μ.
m of unstretched film was obtained. This unstretched film is the first
Biaxial stretching was sequentially performed under the conditions shown in the table to obtain a film of 20 μm. The physical properties of the obtained film are shown in Table 2.

Comparative Examples 1 to 4 The same nylon 46 and nylon MXD6 as in Examples 1 to 5 were individually melted at 300 ° C. and 265 ° C. and extruded from a T die onto a cooling roll kept at 60 ° C. to prepare an unstretched film. Then
This was biaxially stretched under the conditions shown in Table 1 (Comparative Example 1,
2).

Further, 95 parts by weight of nylon 46 and 5 parts by weight of nylon MXD6 were melt-mixed, pelletized and similarly biaxially stretched (Comparative Example 3). 20 parts by weight of nylon 46 and nylon M
80 parts by weight of XD6 was melt mixed and biaxially stretched in the same manner (Comparative Example 4). The physical property values of these films are shown in Table 2.

As can be seen from Table 1, the films of Comparative Examples 1 and 3 have poor stretchability and cannot be formed into a film, and as can be seen from Table 1, the films of Comparative Examples 2 and 4 are inferior in heat resistance. On the other hand, it was found that the gas barrier property was more than 10 times better than the commercially available PET film.

According to the present invention, as is clear from the examples, a film having excellent heat resistance and gas barrier properties can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideo Kato 3-37-19 Koyama, Sagamihara City, Kanagawa Prefecture, Sagamihara Research Center, Teijin Limited (56) Reference JP-A-56-49226 (JP, A) Sho 62-156160 (JP, A) JP 63-128071 (JP, A) JP 2-8246 (JP, A)

Claims (3)

(57) [Claims] 1. A biaxially oriented polyamide film comprising a mixture of 30 to 90% by weight of polytetramethylene adipamide and 70 to 10% by weight of polymethaxylylene adipamide. 2. A mixture of 30 to 90% by weight of polytetramethylene adipamide and 70 to 10% by weight of polymethaxylylene adipamide is melted at a temperature of 290 to 310 ° C., extruded into a film and then rapidly cooled. To obtain an unstretched film, a step of simultaneously or sequentially stretching the unstretched film 2 to 5 times in the machine direction and the transverse direction at a temperature of glass transition point to 150 ° C. to obtain a biaxially oriented film, and If necessary, a biaxially oriented polyamide film obtained by subjecting the biaxially oriented film to a heat treatment at a temperature of 275 ° C. or lower for 1 to 300 seconds. 3. The biaxially oriented polyamide film according to claim 1, which is obtained by an inflation method.