JPH10110096A - Polyamide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nylon 46 film which has a decreased amount of an amine component generating during thermal treatment and has a reduced odor. SOLUTION: This polyamide film comprises a polyamide resin mixture comprising (A) 40 to 90wt.% nylon 46 resin, (A2) 60 to 10wt.% nylon 6 and/or nylon 66 resins and (A3) 0 to 20wt.% copolymer of nylon 6 and nylon 66 [(A1)+(A2)+(A3)=100, (A2)+(A3)<60], and has an amine concentration of 10ppm or less in terms of an amine generating from a film of 1cm<2> and spreading into a volume of 1cm<3> during heat-treating at 120 deg.C for 1 hour.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide film produced mainly by an inflation method or a T-die method, and more particularly to a polyamide film having a small amount of an amine component generated upon heating and having a reduced odor. The present invention relates to a food packaging film made of a polyamide film.

[0002]

2. Description of the Related Art Nylon 46 made of tetramethylenediamine or a functional derivative thereof and adipic acid or a functional derivative thereof is excellent in mechanical strength such as tensile strength, bending strength, impact strength, heat resistance and sliding properties. Therefore, it is a valuable engineering plastic that has great utility value.

Conventionally, this resin is mainly formed by injection molding.
General-purpose polyamides such as nylon 66 have heat resistance,
Although it has been applied to applications in which slidability, chemical resistance, and the like are slightly insufficient, demand for films and extruded products has recently increased. Here, too, nylon 66 is mainly applied to fields where heat resistance is insufficient, and the demand for high heat resistant films is particularly strong especially in the food field.

In these food fields, there are many uses in which food is held in a bag made of a film or covered with a film and heat-treated. Nylon 66 film is melted and cannot withstand use, but its odor is slight and causes almost no problem. On the other hand, it has been found that a nylon 46 film has sufficient heat resistance, but emits a peculiar odor, which is a great obstacle for use in the food field. This is because a raw material (1,4-diaminobutane) specific to nylon 46 is used, and the processing temperature is higher than that of nylon 66 by about 30 ° C., and decomposition components are easily generated.

However, there is no precedent for studying the odor of the nylon 46 film, and since the extrusion processing temperature is about 30 ° C. higher than that of nylon 66, odor components are easily generated and compounds such as known deodorants are decomposed. It was found that the method used for nylon 66 or the like could not be used.

[0006] In order to adapt to the inflation method suitable for forming these films, especially for bag-like shapes, it is desirable to increase the melt viscosity and to lower the crystallization rate. Since these properties were not satisfied, film formation was difficult. To cope with this, it is necessary to increase the viscosity at the time of melting, and the present inventors have proposed a method of adding a special bifunctional compound in Japanese Patent Application Laid-Open No. 8-27378. However, the film produced by this method tends to increase the odor during the heat treatment, and it has become necessary to increase the degree of polymerization of the polyamide mixture by another method.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to produce mainly an inflation method or a T-die method. An object of the present invention is to provide a polyamide film in which an amine component generated during a heat treatment is reduced so as to be particularly suitable for a disliked use.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies from the following viewpoints in order to achieve the above object,
The present invention has been reached. 1) A method for producing a nylon 46 mixture having a low degree of generation of an odor component and easy to form a film, and having an increased degree of polymerization 2) A deodorant that reacts with an odor component that can be added to the nylon 46 mixture during extrusion 3) Extrusion method for removing deodorant components generated during extrusion 4) Method for removing odor components by post-treatment of manufactured film

The present invention relates to (A1) nylon 46 resin
9090 wt% (A2) 60 to 10 wt% of nylon 6 and / or nylon 66 resin and (A3) a polyamide resin mixture consisting of 0 to 20 wt% of a copolymer of nylon 6 and nylon 66 [(A1) + (A2) + (A3) = 10
0, (A2) + (A3) <60], and is a film produced by any one of the following methods (I), (II), (III) and (IV) or a combination thereof. the concentration of the amine component generated in 1 cm ³ than the film of 1 cm ² upon time heat treatment (measured by a Kitagawa gas detector tube method) is 10
Polyamide film with reduced odor of less than ppm. (I) A method of adding a deodorant having an ability to remove an amine component of 0.1 to 7% by weight to a polyamide resin mixture (II) A method of forcibly replacing air enclosed in a tube when manufacturing by an inflation method (III) A method of using an extruder with a vacuum vent function at the time of production and maintaining the pressure at the vent portion at 300 mmHg or less. (IV) The produced film is heated to 60 mm or more at 100 mmHg.
It is a method of keeping under a vacuum of g or less.

Hereinafter, the present invention will be described in detail. The nylon 46 resin as the component (A1) used in the present invention is mainly a polyamide obtained by a condensation reaction using adipic acid or a functional derivative thereof as an acid component and tetramethylenediamine or a functional derivative thereof as an amine component. As a target, a component in which a part of the adipic acid component or the tetramethylenediamine component is replaced with another copolymer component may be used.

Preferred embodiments of the nylon 46 resin are described in JP-A-56-149430 and JP-A-56-1494.
No. 31 is described.

The nylon 6 resin of the component (A2) used in the present invention means a linear polymer obtained by polymerizing ε-caprolactam, but within a range not impairing the basic properties of nylon 6, ε-caprolactam is used. A monomer other than caprolactam may be copolymerized or blended.

The nylon 66 resin of the component (A2) used in the present invention is a polyamide mainly composed of polyhexamethylene adipamide and hexamethylene adipamide unit. A substantially equimolar salt of methylenediamine and adipic acid is charged together with water into a polymerization tank, and the polymerization can be performed at a temperature of about 250 to 300 ° C. under normal pressure, pressure, or reduced pressure.

The copolymer of nylon 6 and nylon 66 as the component (A3) used in the present invention is prepared by charging ε-caprolactam and a substantially equimolar salt of hexamethylenediamine and adipic acid together with water into a polymerization tank. It can be obtained by a usual melt polymerization method. Here, the proportion of nylon 6 in the copolymer is 5 to 95 mol%, and preferably 10 to 90 mol%.

In the present invention, the proportion of (A1) in the polyamide resin mixture is 40 to 90% by weight, and (A2)
Is 60 to 10 wt% and (A3) is 0 to 20 wt% [(A1) + (A2) + (A3) = 100, (A2)
+ (A3) <60]. Here, the effect of adding the components (A2) and (A3) is to lower the crystallization speed and facilitate the film formation. Without the addition of (A2) and (A3), the crystallization rate is too high, and it is extremely difficult to form a film. In particular, it is virtually impossible to form a film by the inflation method. Here, the addition amount of the component (A2) is 10 to 60%, particularly preferably 25 to 45%. If it is less than 10%, the effect of lowering the crystallization rate is not sufficient, and if it is more than 60%, the melting point is lowered and the high heat resistance characteristic of nylon 46 is impaired. The addition amount of the component (A3) is 0 to 20%, and particularly preferably 3 to 10%. When (A3) is more than 20% or (A2) + (A3) is more than 60%, the high heat resistance characteristic of nylon 46 is impaired.

If the above polyamide resin mixture is used,
The crystallization rate is reduced compared to the case of the nylon 46 resin alone, and the film formation is extremely easy. However, in the case of the film formation by the inflation method, it is necessary to impart a high melt viscosity that can be further adapted to the process. . In order to increase the melt viscosity, it is necessary to bond the terminal groups of polyamide to increase the degree of polymerization.
A method using a special bifunctional compound proposed in Japanese Patent Publication No. 378 or a solid phase polymerization method can be considered.

The present inventors have studied various methods. As a result, in order to obtain a film with reduced odor, which is the object of the present invention, by an inflation method, it is essential to increase the degree of polymerization by a solid phase polymerization method. And measuring temperature 300
It has been found that it is necessary to use a polyamide resin mixture having a melt viscosity of 7000 poise or more measured at 100 ° C. and a shear rate of 100 (1 / S). JP-A-56-14943 as solid-state polymerization method
The method described in Japanese Patent Publication No. 0 or JP-A-56-149431 can be used. In the case of using a method other than the solid-phase polymerization method, compounds having an action of bonding end groups are added, but when these compounds are melted in a film manufacturing process, generation of a compound causing odor is generated. Inviting is not preferred.

Films can be obtained by using the polyamide resin mixture described in detail above, but these films contain an amine component originating in nylon 46 and cause a peculiar odor. . In particular, when used for food applications, the treatment is often performed at a high temperature of 180 ° C. or higher, but in such a case, the amine component in the film is volatilized and the odor is further increased, which is an obstacle to use.
Examples of such amine components include pyrroline, pyrrolidine,
And cyclopentylamine. The present inventors measured the amount of the amine component contained in the film by the following method, and in order to suppress the odor generated during the heat treatment as described above to a level that does not hinder practical use, the amount of the amine component was reduced. 10pp
m, preferably 5 ppm or less.

Amine component measurement method: A 600 cm ² film was placed in a 600 ml Erlenmeyer flask and heated at 120 ° C. for 1 hour.
After cooling at room temperature for 30 minutes, the concentration of the amine component in the flask is measured by a Kitagawa gas detector tube method.

One of the methods for achieving the object of the present invention is to add a compound which reacts with these amine components to a polyamide mixture as a deodorant having an amine removing ability, to capture the amine components and heat-treat the mixture. It is to reduce the odor at the time. For this purpose, it is necessary to have the ability to react with the above-mentioned amine component and to have high heat resistance which does not deteriorate at the processing temperature of nylon 46. The present inventors have conducted intensive studies and found that the following compounds satisfy this condition: sulfate (iron sulfate, aluminum sulfate, aluminum potassium sulfate, copper sulfate, zinc sulfate, tin sulfate), oxide (oxidation One or more compounds selected from aluminum, calcium oxide, silicon oxide, titanium oxide, zirconium oxide), zinc carbonate, and zinc chloride. Among them, aluminum compounds and zinc compounds are preferable, and sulfates such as potassium aluminum sulfate and aluminum sulfate are particularly effective. 0.5 to 7 wt. Of these compounds in a polyamide mixture
%, Desirably 1 to 4% by weight, and then manufactured by a usual inflation method or T-die method, a film with reduced odor can be obtained. At this time, the added amount is 0.
If it is less than 5 wt%, the deodorizing effect is not sufficient, while 7 wt%
%, The film becomes brittle, making it difficult to form a film and impairing the transparency of the film. As a method for adding these compounds, a method of extruding and kneading into a polyamide mixture, a master chip of a deodorant (base polymer is any of nylon 46, nylon 66, and nylon 6, or a mixture thereof) is used. Or a method of mixing the deodorant powder itself with the polyamide mixture. Among them, a method using a nylon 6 or nylon 66 master chip as a deodorant is advantageous.

Another method of reducing odor is to physically remove the amine component during the filming process, one of which relates to the inflation method. In the inflation method, a resin extruded from a die is formed into a tube under a specific blow ratio, and after taking a certain distance, the tube is folded and wound. At this time, a certain volume of air is sealed in the tube in order to maintain the shape of the tube, but the amine component volatilized from the film accumulates in the tube and hinders the volatilization and removal of the amine component from the film. It will be. As a result of intensive studies, the present inventors have found that if the air enclosed in the tube is forcibly replaced, the amine component is volatilized and removed from the film during the film formation process, thereby reducing odor.
This can be carried out industrially by introducing a certain amount of air into the tube while measuring the tube diameter, and taking out the air so that the tube diameter becomes constant. At this time, the larger the air exchange amount, the more advantageous the odor reduction,
It is desirable that the amount of air exchange per minute be at least one time based on the volume in the tube. If the ratio is less than 1, the deodorizing effect becomes insufficient. There is no particular upper limit on the replacement amount, and it is desirable that the replacement amount be large as long as the tube diameter can be controlled. A particularly preferable air replacement amount per minute is 7 times or more based on the volume in the tube.

Another method for removing the odor during the film forming step is to use an extruder having a vacuum vent function and remove the amine component from the vent portion by means of vacuum suction. At this time, it is necessary to maintain the pressure at the vent at 300 mmHg or less. If it is more than this, the effect of removing odor is insufficient. Particularly preferred is 10 mmHg or less.

Another way to reduce the odor of the film is by post-treatment of the produced film. As a result of intensive studies on a method for reducing odor by post-treatment, the present inventors have found that heating and vacuum treatment are effective. That is, the odor can be reduced by holding the film itself at a temperature of 60 ° C. or more and under a vacuum of 100 mmHg or less. The preferred condition is that the heating is performed at a temperature of 80 ° C. or more and a vacuum of 10 mmHg or less is maintained for 10 minutes or more. Above all, the temperature condition is important, and it is necessary that the temperature of the film itself exactly conforms to the above conditions.

By using the above-mentioned deodorizing methods alone or in combination, it is possible to obtain a film with a reduced odor. In this case, the film thickness is 10 to 150.
μm is desirable. If the thickness is less than 10 μm, not only properties (strength, etc.) as a film become insufficient, but also
It is difficult to make a homogeneous product. On the other hand, when the thickness is 150 μm or more, deodorization by other methods becomes difficult except when a deodorant is used. A thickness of 20-100 μm is most suitable for the application of the present invention.

One of the uses in which the film with reduced odor produced by the method described above can exhibit its characteristics is a food heating bag. Recently, a method of heating food at a high temperature of about 200 ° C. for a short time (30 to 60 seconds) with an instant heating cooker has been attracting attention. At this time, it is necessary to wrap the food in a film, There was a need for a durable film. It has been found that the film of the present invention is not only excellent in heat resistance but also generates little odor during high-temperature treatment and is very suitable for this use. Among them, an inflation film is particularly suitable because it is easy to make a bag. These bags are not only preferably used as the above-mentioned food heating bags, but are expected to greatly expand their use as heating bags for various articles and bags for heat sterilization in the future.

[0026]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition, the measurement of the various characteristics in an Example and a comparative example was based on the following method. (1) Crystallization temperature: Using a Differential Scanning Calorimeter Model 901 manufactured by TA Instruments, the temperature was raised to 330 ° C. at a heating rate of 20 ° C./min, and held for 3 minutes, followed by a cooling rate of 20 ° C./min. And the temperature was measured. (2) Melt viscosity: Measured at a measuring temperature of 300 ° C., a holding time of 4 minutes and a shear rate of 100 (1 / s) using a Rheograph 2002 manufactured by Gottfeld. (3) Amine component concentration: 6 in a 600 ml Erlenmeyer flask
After placing a 00 cm ² film and heating at 120 ° C. for 1 hour, the mixture is allowed to cool at room temperature for 30 minutes, and the concentration of the amine component in the flask is measured by a Kitagawa gas detector tube method.

In Examples and Comparative Examples, the following materials were used. Constituent (A1) Nylon 46 as Dutch DS
STYLKS400 manufactured by M Corporation was used. Constituent (A2) Nylon 6 manufactured by Tenaka Co., Ltd.
As H8001 and nylon 66, Leona 1300S manufactured by Asahi Kasei Corporation was used. Constituent component (A3) 85 mol% of ε-caprolactam,
Hexamethylenediamine adipate (AH salt) 15
Mol% in a polymerization vessel, polymerized under a steam pressure under a normal melt polymerization method, washed with hot water, and dried to obtain 3%.
A chip having η _rel = 1.47 and a water content of 0.05% in a _metacresol solvent at 5 ° C. was obtained. The deodorant master chip was prepared by mixing 30 wt% of a deodorant (potassium aluminum sulfate) with NH8001 manufactured by Tenaka Co., Ltd., and using a twin-screw extruder (TEX44, manufactured by Nippon Steel Works) with a cylinder temperature of 25.
It was extruded into chips at 0 to 270 ° C.

The polyamide resin mixtures of Examples and Comparative Examples were extruded into chips at a cylinder temperature of 270 to 330 ° C. using a twin screw extruder (TEX44, manufactured by Nippon Steel Works).

The solid phase polymerization method in Examples and Comparative Examples was carried out by maintaining the polyamide resin mixture in a vacuum tumbler type heater at 220 ° C. for 14 hours under a vacuum of 5 mmHg or less while mixing.

The inflation method in Examples and Comparative Examples uses a single screw having a diameter of 50 mm and L / D = 30.
The cylinder temperature is 280-300 ° C and the die head temperature is 290, using equipment with a die diameter of 100 mm (downward method).
The film was manufactured by operating at ３００300 ° C. In addition, at this time, a certain amount of air is introduced into the tube through a flow meter, and the tube diameter is measured separately with a sensor to maintain a constant value.
The air was taken out so as not to change, and the deodorizing effect was tested. In addition, the screw was replaced with a vent type screw with this apparatus, and a film was formed while vacuum suction was being applied to the vent portion to test the deodorizing effect.

In the T-die method in Examples and Comparative Examples, a film was extruded at a cylinder temperature of 270 to 300 ° C. and a die temperature of 290 to 300 ° C. using an SZW40 type device (using a 40 mm single screw) manufactured by Technovel Corporation. did. In this device, replace the screw with a vent type one,
The film was formed while vacuum-suctioning the vent, and the deodorizing effect was tested.

The heating and vacuum post-treatments in Examples and Comparative Examples are as follows:
This was performed by setting the film in a vacuum dryer heated to a predetermined temperature and maintaining the film under vacuum for a predetermined time.

Tables 1, 2, and 3 show the production methods, compositions, test conditions, and test evaluation results as examples and comparative examples.
In the table, “inflation” in the column of the production method means the inflation method.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

The film forming properties in the table were determined based on the take-up property, thickness unevenness, surface properties and the like during the film forming.

Examples 1 to 16 and Comparative Examples 1 to 8 "Inflation method" Nylon 46 alone (Comparative Example 2), system without solid-phase polymerization (Comparative Example 1), system with too much deodorant (Comparative Example 3) In a system in which the film thickness was too small (Comparative Example 4), the film-forming properties were poor, and film production was impossible. In the system to which the deodorization method described in this specification is not applied (Comparative Example 5), the amine component concentration is 12 ppm, which is a level at which odor becomes a problem. Further, in a system containing a large amount of components other than nylon 46 (Comparative Example 6), when heated to 220 ° C. in an instant heating cooker, it melted and had insufficient properties. On the other hand, typical examples are shown in Examples 1 to 4. In each case, a film having an amine component concentration of 10 ppm or less was obtained with good film-forming properties. Examples 5 to 7 show the effect of the combined use of the deodorizing methods, but the concentration of the amine component is lower than in the case of using each alone. Example 8 is an example in which components other than nylon 46 were reduced. The effects of the temperature in the heating vacuum treatment were examined in Examples 4, 9, and 10, and the higher the temperature, the more effective. No effect is exhibited at a lower temperature (Comparative Example 7). In Example 11, although the film thickness was increased, desired effects were observed.

"T-die method" In the system to which the deodorizing method shown in the present specification is not applied (Comparative Example 8), the amine component concentration is extremely high, whereas in Examples 12, 13, and 14, the amine component concentration is 10 ppm or less. Has been reduced to There is also a combined effect (Example 15), and even when the film thickness is increased, the deodorizing effect is recognized.

Example 17 Using the film produced by the method of Example 10, the film was cut into a length of 24 cm, and one end was heat-sealed to form a bag. When bread was put in this bag and heated at about 220 ° C. for 35 seconds in a flash cooker,
There was no film damage such as melting, and the bread was baked and heated to the same state.

[0041]

According to the present invention, it is possible to obtain a film having excellent mechanical strength and heat resistance and having little odor generated upon heating. Even if this film is used for heating in a state where the food is packaged, generation of odor from the film is sufficiently small, and the film can be suitably used for food packaging.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FIB29L 7:00)

Claims (10)

[Claims] 1. (A1) Nylon 46 resin 40 to 90 wt.
% (A2) Nylon 6 and / or Nylon 66 resin
60-10 wt% and (A3) nylon 6 and nylon 6
Polyamide resin mixture consisting of a copolymer with 0 to 20 wt% [(A1) + (A2) + (A3) = 100, (A
2) + (A3) <60], a polyamide film having a concentration of an amine component of 10 ppm or less in 1 cm ^{3 of} a 1 cm ² film when heated at 120 ° C. for 1 hour. 2. (A1) Nylon 46 resin 40 to 90 wt.
% (A2) Nylon 6 and / or Nylon 66 resin
60-10 wt% and (A3) nylon 6 and nylon 6
Polyamide resin mixture consisting of a copolymer with 0 to 20 wt% [(A1) + (A2) + (A3) = 100, (A
2) + (A3) <60], and the following methods (I) and (I
A film produced by any of I), (III) and (IV) or a combination thereof, and a concentration of an amine component generated in 1 cm ³ from a 1 cm ² film when heated at 120 ° C. for 1 hour ( Polyamide film with reduced odor of less than 10 ppm (measured by Kitagawa gas detector tube method). (I) A method of adding a deodorant having an ability to remove an amine component of 0.1 to 7% by weight to a polyamide resin mixture (II) A method of forcibly replacing air enclosed in a tube when manufacturing by an inflation method (III) A method of using an extruder with a vacuum vent function at the time of production and maintaining the pressure at the vent portion at 300 mmHg or less. (IV) The produced film is heated to 60 mm or more at 100 mmHg.
How to keep under vacuum under g 3. The polymerization degree can be increased by a solid-state polymerization method, and the melt viscosity measured at a measurement temperature of 300 ° C. and a shear rate of 100 1 / s is 7%.
The polyamide film according to claim 1, comprising a polyamide mixture having a molecular weight of 000 poise or more and produced by an inflation method. 4. The deodorant having the ability to remove amine components in (I) is a sulfate (iron sulfate, aluminum sulfate, aluminum potassium sulfate, copper sulfate, zinc sulfate, tin sulfate),
The polyamide film according to any one of claims 1 to 3, wherein the polyamide film is at least one compound selected from oxides (aluminum oxide, calcium oxide, silicon oxide, titanium oxide, and zirconium oxide), zinc carbonate, and zinc chloride. 5. The polyamide film according to claim 1, wherein the amount of air exchange per minute in (II) is at least one time based on the volume of the tube by an inflation method. . 6. The polyamide film according to claim 1, wherein the polyamide film is produced by an inflation method or a T-die method, and a pressure at a vent portion in (III) is 10 mmHg or less. 7. The polyamide film according to claim 1, wherein the holding in (IV) is heating under 80 ° C. or more and under vacuum of 10 mmHg or less for 10 minutes or more. 8. The polyamide film according to claim 1, wherein the film has a thickness of 10 to 150 μm. 9. The polyamide film according to claim 1, wherein the concentration of the amine component generated from the film is 5 ppm or less. 10. A food heating bag comprising the polyamide film according to any one of claims 1 to 9.