JPS61189922A - Molecularly orientated polytetramethylene adipamide film - Google Patents

Abstract

PURPOSE:To obtain the film with heat resistance and rigidity, keeping its toughness by a method in which the film is made of polytetramethylene adipamide and is at least uniaxially and molecularly orientated, and its primary tensile elastic modulus in an orientation direction is caused to be of a specified value or more. CONSTITUTION:A film is made, melting and solidifying the polymer substantially composed of polytetramethylene adipamide, and it is orientated at least in a uniaxial direction, thereby carrying out orientation crystallization as well as molecular orientation. Then the crystallization degree containing the anneal after orientation, is heightened, and the objective film is obtained. The tensile elastic modulus equal to 300kg/mm<2> or higher corresponds to the film of biaxial orientation. Generally, at the secondary working of the film, the film runs very smoothly at good productivity and the condition where no problems occur is satisfied. The film density range of 1.18-1.23g/cm<3> has the action of discriminating clearly in the dimension stability of the film at heating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel polyamide film, particularly an aliphatic polyamide film having excellent heat resistance and high rigidity.

Conventionally, in the field of polyamide film, its intermolecular force (hydrogen bonding force) has been mainly utilized to produce films for food packaging, etc.
There are aliphatic polyamide films used in the packaging film field, such as nylon 6 and nylon 8.6 films (non-oriented or 1-biaxially oriented films), and considering their low melting point. Nylon 11 and nylon 12 films were known for adhesive film applications.

On the other hand, aromatic polyamide films have been actively developed in recent years for industrial applications that take advantage of their heat resistance and rigidity, such as tapes and electrical insulation. It is a molecularly oriented film using aliphatic polyamide, and its intended industrial application field is heat resistance and toughness, which were limited by each of the above-mentioned conventional films, and mainly due to its toughness under heat. Fields that require 1. For example, retort food packaging applications,
It is used for general packaging and industrial purposes, such as automobile oil containers (pouch-like), lightweight containers (bags) for hot solutions, waste liquids, etc.

[Conventional Technology 1 As mentioned in Tama, conventionally known films had limitations in film performance due to the inherent properties of their polymers.For example, an aliphatic polyamide film, which is closest to the film of the present invention, Biaxially stretched film of nylon 6 (disclosed in Japanese Patent Publication No. 43-9399, Japanese Patent Publication No. 44-2598, etc.), biaxially stretched film of nylon 6.
-16058, etc.) are examples of typical polyamide oriented films that utilize the intermolecular force (hydrogen bonding force) of aliphatic polyamide, but each is an essential characteristic of the polymer. There are limits to film properties due to melting point, crystal structure, etc., and the melting point is high (265°C).
Even for nylon 6 and 6, which can have a high degree of crystallinity, the L limit of the temperature at which the oriented film can be used practically is about 140°C even after a short thermal history such as retort treatment, and for nylon 6 it is also 120°C. In addition, one of the problems with conventional polyamide film is that it lacks rigidity.For example, it can be used as a packaging film, causing problems such as wrinkles and pitch deviations during lamination and printing, and can be used with adhesive tapes, etc. As a base film, problems such as elongation and wrinkles were likely to occur during coating processing. The initial tensile modulus is most suitable as a typical characteristic representing the rigidity of these films, and is approximately 180 to 220 kg/+++a2 for nylon 6 (biaxially stretched film) and approximately 230 for nylon 6.6 (biaxially stretched film). ~300kg
/mm2.

[Problems to be Solved by the Invention] As mentioned above, the problems with conventionally known techniques, especially aliphatic polyamide films, are firstly the heat resistance during use, and secondly the firmness or rigidity of the film. The object of the present invention is to have a low initial tensile modulus.
Toughness is mainly based on these two points, namely, the intermolecular force based on the hydrogen bonds between molecules that aliphatic polyamide inherently holds (the characteristic values for the film are puncture strength,
The objective is to obtain a film that has heat resistance and rigidity A that could not be achieved with conventionally known aliphatic polyamides, while maintaining properties such as friction and abrasion resistance, bending fatigue resistance, and impact resistance. It is.

A film with this toughness, rigidity, and heat resistance was completely unknown until now, and it is a novel material not only for packaging film applications, but also for future cutting-edge technology fields such as electrical and electronic fields and biochemistry fields. It is used as a.

[Means and effects for solving the problems] As a means for solving the above problems, the inventors have conducted extensive studies and found that the polymer constituting the film is essentially polytetramethylene adipamide. (Hereafter, nylon 4/6
) was selected. As is well known, this polymer has been known in the literature for a long time, but it has only recently been put into practical use industrially after its manufacturing method was disclosed in JP-A-5Ei-149430 and JP-A-149431. It is a growing polymer, and up until now nothing was known about its use in film. There was a possibility that this polymer, which has a melting point of 295°C, could contribute to solving the problem in terms of heat resistance, but it is necessary to control its crystallization behavior (mainly stabilization by the degree of crystallization achieved and its completeness). Regarding the initial tensile modulus of elasticity of the film, which is another problem, the specific means was to provide as much molecular orientation as possible. That is, a polymer consisting essentially of nylon 4.B is melted and solidified to form a film, and this is stretched and oriented in at least one axis to promote oriented crystallization simultaneously with molecular orientation. The desired film was obtained by increasing the crystallinity including 7-neel. In this case, the tensile modulus is 300 kg/mm2
The above corresponds to biaxially oriented films and is generally used for secondary processing of films (printing, coating, laminating).
This value has been set as a guideline to ensure that the film runs extremely smoothly and with good productivity and that no problems occur. The structure of the present invention is a film oriented at least in the l-axis using nylon 4 and 6 as a means for solving these problems, and has a film of 300 k
The film has an initial tensile modulus of at least g/am2, preferably at least 350 kg/mm2. Film density 1
．． The range of 18 to 1.23 g/cm3 further clarifies the range of the film of the present invention, and the effect of the film of the present invention in heat resistance can be considered in terms of dimensional stability of the film under heat. has a clearly differentiating effect compared to conventional nylon 6 or nylon 6.6 films, i.e. 180
The heat shrinkage (dry) rate at 30 minutes at ℃ is maintained at 0.5% or less, and is made of nylon 6 (biaxially oriented film).
The film shape becomes extremely unstable near the softening temperature, causing more than 10% shrinkage or fusion, while nylon 6/6 (biaxially oriented film) shrinks 2-3% and shrinks 1-20%. decrease in film elongation (i.e. oxidative degradation)
accompanied by. If the density exceeds 1.23 g/cm3, the film becomes brittle, which is not preferable.

The film of the present invention may be any polymer consisting essentially of polytetramethylene adipamide, and is generally known in the art to be a blend of small amounts of polymers, especially of the same type of polymer. Mixing of polyamide resin, addition of heat stabilizers, lubricants, crystal nucleating agents, pigments, metal powders, flame retardants, etc. can be selected freely as long as the purpose of the present invention is not impaired. In addition, there are no particular restrictions on the molecular weight of the polymer, and generally speaking, if the method of film formation is a melt casting method (inflation method, T-die method, etc.), the extrudable molecular weight range of the polymer (as a guide, 96% sulfuric acid .1
The relative viscosity of the weight percent solution is 260 to 10.0, preferably 3.0 to 5.0. ) can be used.

Furthermore, for molecular orientation, no matter which conventionally known forming methods such as uniaxial stretching, uniaxial rolling, biaxial stretching, biaxial rolling, press rolling, etc. are used, the initial tensile modulus, which is a requirement for the film of the present invention, is It is sufficient if it satisfies at least 300 kg/mm2. However, as for biaxial orientation, it is well known that simultaneous stretching is the easiest method for conventional aliphatic polyamides.

[Examples] The configuration of the present invention has been described in detail above, but in order to make the present invention more specific, it will be described below using Examples. However, the present invention is not limited to the following examples.

Example 1 A polytetramethylene adipamide resin having a relative viscosity of 3.3 measured as a 0.1% by weight solution in 96% sulfuric acid (20°C) was dried to a moisture content of 0.01% or less and placed in a nitrogen atmosphere. T-d is melted at 320℃.
A film having a thickness of 150 mm was extruded from the ie, and rapidly solidified on a water-cooled cooling drum. This unstretched film (150 g) was introduced into a regular roll-type longitudinal stretching machine and stretched 3.5 times and 4 times in the longitudinal direction at a preheating temperature of 80°C and a stretching temperature of 120°C. A film of 42μ and 37JL was obtained by contact heat setting for 5 seconds. The initial tensile modulus of this film is JIS-C-23
As measured by the method of 18, a film stretched 3.5 times was 340 kg/am, and a film stretched 2.4 times was 370 kg/am.
g/mm2. The density of the film was measured using a density gradient tube and was found to be 1.2 for both samples.
It was 0g/cm3. In addition, this film is heated at 180℃,
The heat shrinkage after standing for 30 minutes was 2.5% in the vertical direction and 0% in the horizontal direction.

Example 2 The 150p unstretched film obtained in Example 1 was vertically
It was cut out into a square of 15c+s in width, set in a batch-type biaxial stretching machine (TM-Long machine), and biaxially stretched at 110° C. to 3.2 times in length and width at the same time. After stretching, this film was fixed with gold cotton and placed in air at 260° C. for 8 seconds to anneal it. The obtained film (18
JL) has an initial tensile modulus of 310k in both the vertical and horizontal directions.
g/lll112, and the density is 1.18g/cm3
Met. The shrinkage rate of the Naoki film after 30 minutes at 180° C. was 3% or less in all directions, and the puncture strength according to the JAS standard was 1.5 kg.

[Effects of the Invention] The effects of the present invention are summarized as follows. That is, the performance provided by the film of the present invention far exceeds the limits of heat resistance and rigidity of conventionally known aliphatic polyamide films, such as biaxially stretched nylon B.
The greatest effect can be said to be that it has created a film that opens up a new field, retaining the characteristics of aliphatic polyamide films that could not be exhibited even with polyester films (for example, polyester films).

Claims (2)

[Claims] (1) A film consisting essentially of polytetramethylene adipamide with at least uniaxially oriented molecules, the initial tensile modulus of which is at least 300 kg/m in the oriented direction.
A molecularly oriented polytetramethylene adipamide film characterized by having a molecular orientation of m^2 or more. (2) Film density is 1.18-1.23g/cm^
2. A molecularly oriented polytetramethylene adipamide film according to claim 1.