JPS6119653B2 - - Google Patents

Description

[Detailed description of the invention]

An object of the present invention is to provide a polyamide stretched film, particularly a polyamide stretched film whose main component is an aliphatic polyamide such as polycapramide (nylon-6) or polyhexamethylene adipamide (nylon 66); The object of the present invention is to provide a polyamide stretched film with improved mechanical properties. Yet another object is to provide an industrially advantageous method for producing such films. Nylon 6 and nylon 66 films are heat resistant,
As a tough, high-performance film with excellent cold resistance and impact resistance, it is an important material indispensable for packaging frozen foods, etc., but its industrial production is not easy. Conventionally, these stretched films could be produced by extruding a molten polymer through a T-die and simultaneously biaxially stretching it, or by extruding it through a cylindrical die and using inflation, but the former method required extremely complicated and expensive equipment. In the latter case, it was difficult to obtain thickness accuracy and mechanical properties due to non-uniform stretching orientation. Therefore, a sequential stretching method has been considered as a method that is more superior in terms of productivity and quality. Method for suppressing crystallization of film during roll stretching (Japanese Patent Publication No. 47-3195
Although many studies have been carried out, such as the above, no satisfactory results have been obtained. The present inventors previously succeeded in easily obtaining a stretched film of aliphatic polyamide by mixing a copolyamide containing meta-xylylene diamine with aliphatic polyamide and melt-extruding the mixture. After repeated research, they discovered that by mixing cheaper copolymers, an effective stretched film could be obtained with a small amount of mixing, leading to the completion of the present invention. That is, 50 to 97 parts by weight of aliphatic polyamide (component A) based on the total amount of resin, (a) 3 to 80 mol% of caprolactam, (b) one or more aliphatic diamines having 4 to 12 carbon atoms and carbon 3 to 80 mol% of polyamide forming units consisting of one or more types of aliphatic dicarboxylic acids having numbers 4 to 36
and (c) 3 to 90 mol% of polyamide-forming units consisting of one or more aliphatic or alicyclic diamines and one or more aromatic dicarboxylic acids and/or alicyclic dicarboxylic acids (a), ( A polyamide-based stretched film consisting of a polymer mixture of 3 to 50 parts by weight of copolymerized polyamide (component B) based on the total resin amount, in which b) and (c) are polymer constituent units; This is a method of manufacturing the film. Compared to producing films from polyamides containing metaxylylene diamine as the main component, such as polymethaxylylene adipamide, (a) caprolactam and
(b) a polyamide-forming component made of one or more aliphatic diamines and aliphatic dicarboxylic acids; and (c) a polyamide-forming component made of xylylene diamine and one or more aromatic dicarboxylic acids or alicyclic dicarboxylic acids. By mixing and melting component B, such as a terpolymer, into an aliphatic polyamide, the effect of improving the sequential stretchability of the film is even more remarkable, and it is effective in small amounts, has high productivity, and can be easily commercially produced at low cost. We discovered this and succeeded in making it possible to generalize the production of sequentially stretched polyamide films. Of course, it goes without saying that uniaxial stretching and simultaneous stretching are possible by mixed melting, but even in this case, the stretchability is improved compared to the case of using component A alone such as nylon 6 or nylon 66. There is. The role of these copolymers is not clear, but nylon 6, nylon 66 or nylon
In the case of 610, after uniaxial stretching, the subsequent stretching in the perpendicular direction becomes difficult due to strong constraints due to the crystal orientation accompanied by the formation of strong hydrogen bonds between molecules, whereas these low-crystalline It is thought that this is because the mixing and melting of the copolymer inhibits the strong oriented crystallization during the initial uniaxial stretching, and then the constraint on deformation becomes smaller. Conventionally, many studies have been made for a long time regarding the mixed melt extrusion of different types of polyamides in order to improve the physical properties of nylon filaments. For example, by spinning a mixture of low-melting point polyamide and high-melting point polyamide to obtain an ironable fiber with a melting point of 230°C or higher (US Pat. No. 2,193,529), and improving the flat spot problem of tires by using nylon 6 or nylon 66 tire cord. As described in US Patent No.
3195603 specification), spinning of polycapramide or polyhexamethylene adipamide melt mixed with 5 to 80 parts by weight of polyamide having a glass transition temperature of 140°C or higher (US Patent No. 3393252 specification), or As a method for improving the stiffness of nylon 6 or nylon 66 fibers, 5 to 40 parts by weight of a polyhexamethylene isophthalamide copolymer is mixed with polycapramide or polyhexamethylene adipamide and melt-spun (Japanese Patent Publication No. 11830-11830) Publication No.) etc. In both cases, the dimensional stability and Young's modulus of nylon fibers are improved by dispersing and filling polyamide with a rigid structure, and it can be easily inferred that the improvement in stretchability of polyamide stretched films such as those of the present invention is achieved. Such research has never been seen before. Commercially produced polyamide films include nylon 6, nylon 66, or nylon 12.
There are films of aliphatic polyamides such as, and their physical properties are superior to other polyolefin films, polyester films, cellophane, etc., such as impact resistance, cold resistance, pinhole resistance, and oil resistance. On the other hand, if it is weak and thin, there are problems with printing and automatic packaging, and although it has excellent heat resistance, it shows a decrease in strength when sterilized using super steam or hot water of 120℃ or higher, and it does not have sufficient gas barrier properties. There are some points that need improvement, such as points that cannot be said to be satisfactory. In the present invention, various properties can be imparted by changing the composition of component B, mixing ratio, or stretching conditions, and it is also important that it makes it possible to provide various improved polyamide stretched films.
For example, when polycapramide is used as component A, it generally has a breaking strength of 15 to 30 Kg/mm ² and a Young's modulus of 150 to 340 Kg/mm 2 .
mm ² , impact strength 7-15Kg・cm/25μ, low-temperature impact strength 6-12Kg・cm/25μ, impact strength after 30 minutes treatment with 120℃ hot water 3.5-7.0Kg・cm/25μ, oxygen permeability coefficient 1×
It can change like 10 ^-13 ~3×10 ^-12 cc・cm/cm ²・sec・cmHg. The main copolyamide of component B used in the present invention is (a) 3 to 80 mol% of caprolactam, (b) one or more aliphatic diamines having 2 to 12 carbon atoms and 4 carbon atoms.
3 to 80 polyamide-forming units consisting of one or more of 36, preferably 4 to 12 aliphatic dicarboxylic acids.
mol% and (c) 3 to 90 mol% of polyamide forming units consisting of one or more aliphatic or alicyclic diamines and one or more aromatic dicarboxylic acids or/and alicyclic dicarboxylic acids. , (b), and (c). The aliphatic diamines mentioned here include ethylene diamine, propylene diamine,
Butylene diamine, pentamethylene diamine, hexamethylene diamine, 2-methylhexamethylene diamine, and/or 3-methylhexamethylene diamine, 2,2,4-trimethylhexamethylene diamine, and/or 2,4,4-trimethylhexane methylene diamine, 3-t-butylhexamethylene diamine, heptamethylene diamine,
These include octamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, and the like. (c)
In addition to the diamines mentioned above, the component diamines include cyclohexane bismethylamine, isophorone diamine, para-aminocyclohexylmethane, and the like.
In addition, examples of aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, 2-methyl adipic acid, and/or adipic acid.
or 3-methyladipic acid, 3-t-butyladipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, icosandione Examples include dimers of acid, tetracosanedioic acid, oleic acid, and linoleic acid. The aromatic dicarboxylic acids used are terephthalic acid,
Isophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, fluorenedicarboxylic acid, 3-
(4-carboxyphenyl)1,1,3-trimethyl-5-indanecarboxylic acid or structural formula HOOC
-φ-X-φ-COOH is used. X here
is -O-, = _SO2 , = _CR1R2 , and _{R1 and R2} are independently H or alkyl having 1 to 5 carbon atoms, or mutually connected alkylene having 4 to 5 carbon atoms. Examples of alicyclic dicarboxylic acids include hexahydroterephthalic acid, hexahydroisophthalic acid, and hexahydrophthalic acid. If the polyamide component (b), which is composed of aliphatic diamine and aliphatic dicarboxylic acid, exceeds 80 mol%, the effect of improving stretchability will be low. (c) component is a polyamide structural unit made from diamine and aromatic dicarboxylic acid.
If it exceeds 90 mol%, the melt viscosity of the copolymer becomes extremely high, making polymerization and mixing and melting difficult, which is not preferable. Moreover, if the caprolactam component (a) exceeds 80 mol % in the polyamide structural unit, the effect of improving stretchability is low, which is not preferable. The copolyamide used in the present invention is produced by mixing approximately equivalent amounts of the above-mentioned diamines and dicarboxylic acids, or by mixing an aqueous solution or dispersion of a nylon salt with caprolactam, and by a conventional autoclave polymerization method. It can be obtained by heating and drying in a vacuum, but in special cases it can also be produced by a solution method. The solution viscosity of these copolymers is set to such a value that when mixed and melted with component A nylon 6 or nylon 66, fluidity is easy and a uniform film surface can be obtained. Aliphatic polyamide used in the present invention (component A)
is α-type crystal (Y-Kinoshita: Macromol.
Chem., 33, 1, 1959), specifically nylon 4,
Examples include polyamides such as nylon 6, nylon 9, nylon 11, nylon 6.6, nylon 6.10, and nylon 10.10, or copolymers thereof. The mixing ratio of the aliphatic polyamide (component A) and the copolymerized polyamide (component B) is such that component B is at least 3 parts by weight, preferably at least 5 parts by weight, based on the entire mixture (100 parts by weight) in view of sequential stretchability. Even if the amount is increased to 40 parts by weight or more, no further effect of improving sequential stretchability is observed. However, there are improvements in performance such as gas barrier properties, hot water resistance, transparency, and Young's modulus, and as a polyamide film, it is possible to widely change the B component up to 50 parts by weight to obtain products with improved properties over a wide range. . Components A and B are preferably mixed by mixing the respective chips or powders in a conventional V-type or cylindrical blender and then melting and re-pelletizing, or directly melting and extruding without re-pelletizing to form a film. However, it is not particularly limited to this. In the B component copolymer or with A component and B as necessary.
Antioxidants, light stabilizers, antigelation agents, lubricants, antiblocking agents, pigments, antistatic agents, surfactants, or other thermoplastic resins can be added to the mixture with the components. Stretched films are produced by heating to a temperature higher than the melting point of any component of the polyamide mixture mentioned above, extruding the molten polymer through a die, and then heating the film at 90°C.
First, an end-stretched film is prepared by rapidly cooling to the following temperature and solidifying. In the case of uniaxial stretching, this unstretched film is usually stretched between two or more rolls having different peripheral speeds, or by holding the ends of the film with clips in a tenter and pulling the film. The stretching temperature is 40°C or higher and lower than the melting point of the copolymer of component B, preferably 50 to 100°C.
It is. The stretching ratio is 1.5 to 7.0 times, preferably 2.5 to 7.0 times.
It is 5.0 times. The stretched uniaxially stretched film is usually heat treated at a temperature lower than the melting point of component A and higher than the stretching temperature for 5 minutes or less, preferably 5 to 60 seconds under tension or under a certain degree of relaxation. In the case of sequential biaxial stretching, a partially stretched film prepared using a flat die is stretched in the longitudinal direction, and then both ends of the film are held with clips and stretched in the transverse direction substantially perpendicular to the first stage stretching direction. Although this method is commonly used, the order may be reversed to carry out stretching in the transverse direction, followed by stretching in the machine direction. To perform simultaneous biaxial stretching, an unstretched film created using a flat die is stretched simultaneously in the vertical and horizontal directions in a tenter, or a cylindrical unstretched film created using a circular die is stretched using an inflation method. This is done by stretching. The stretching ratio in one direction is at least 2.0 times or more, preferably 3 to 5 times. The stretching temperature is 40°C or higher and lower than the melting point of the component B copolymer, preferably the first stage stretching temperature is set at 50 to 100°C, and the second stage stretching temperature is set at 70 to 120°C. In most cases, the biaxially stretched film obtained in this manner is preferably stretched at a temperature higher than the maximum temperature for stretching and lower than the melting point of component A for 5 minutes or less in order to improve the thermal dimensional stability of the film. is heat treated for 5-60 seconds. During this processing, the film is held either under tension, under a certain amount of relaxation, or in a combination of both. The polyamide film obtained by the present invention is excellent in transparency, mechanical properties, heat resistance, cold resistance, and oil resistance, but it is particularly suitable for biaxially oriented films made of conventionally known aliphatic polyamides that are not melt-blended, such as It has higher mechanical strength than biaxially stretched nylon 6 film, and when processing the film, such as high-speed printing, automatic bag making, and automatic filling packaging, troubles due to low elastic modulus and problems with packaging bags. It has the characteristic that there are fewer problems such as bag breakage during transportation, etc. Furthermore, the film has excellent transparency, good printing ink coverage and clarity, and has the advantage of increasing commercial value. In addition, there is little loss in strength when the packaging bag is sterilized using super steam or high-temperature hot water, making it suitable for heat-resistant packaging. Also nylon-62
Axially oriented films have relatively good gas barrier properties, but the film of the present invention can also provide even better gas barrier properties, and as an aliphatic nylon film, it also has the characteristics of transparency, oil resistance, and cold resistance. Therefore, it is extremely useful for packaging purposes, particularly for heat sterilization storage packaging of foods that are susceptible to deterioration and spoilage, and for storage packaging of drugs that are sensitive to deterioration. These features can be widely changed and controlled by appropriately selecting the composition and amount of the polyamide mixture and the film forming conditions, allowing us to produce a wide range of different types of films with various performances suited to the application. It is possible to provide this service over a period of time. The present invention will be explained in detail below with reference to Examples, and the measurement items in the Examples were measured by the following methods. (1) Melting point (Tm) The temperature at the heat absorption point was measured using a Perkin-Elmer differential calorimeter at a heating rate of 20°C/min. (2) Glass transition temperature (Tg) A sheet-like piece created by melting a chip between two hot plates and then rapidly cooling it was used to absorb heat at a heating rate of 20℃/min using a PerkinElmer differential calorimeter. The point temperature was measured. (3) Relative viscosity (ηr) Polymer concentration 1 g/
The falling time of 100 ml of sulfuric acid solution at a temperature of 25°C was measured using an Ostwald viscometer and expressed as a ratio of the time when only the solvent was used. (4) Severity (Haze) Using a haze meter S type manufactured by Toyo Seiki Co., Ltd.,
Measured according to JIS-K6714. (5) Yield point strength and yield point elongation Measured according to ASTM-D882. (6) Breaking strength and breaking elongation Measured according to ASTM-D882. (7) Impact strength Measured at 20°C and 65% RH using a film impact tester manufactured by Toyo Seiki Co., Ltd., and expressed as per 25 μm thickness. Low-temperature impact strength was measured in a -30°C room. (8) Oxygen permeability coefficient OXTRAN− manufactured by Modern Control, USA
30 using the same pressure method using a POD automatic oxygen permeability meter
Measured at °C. (9) Method for determining aliphatic polyamides that form α-type crystals X-ray pattern at room temperature of a solid obtained by melting and crystallizing the corresponding aliphatic polyamide between the melting point of the aliphatic polyamide and a temperature 30°C lower than the melting point From this, the formation of α-type crystals (Macromol・Chem., 33, 1, 1959) according to Y. Kinoshita's classification is determined. (10) Shrinkage rate Calculated from dimensional changes before and after the film was left in dry heat at 180°C for 30 minutes or in boiling water for 30 minutes. Example 1 and Comparative Example 1 8.71 kg (75 mol) of hexamethylene diamine was mixed with an aqueous dispersion of 3.32 kg (20 mol) of isophthalic acid and 6.65 kg (40 mol) of terephthalic acid in 30 kg of distilled water,
Next, 2.34 Kg (16 mol) of adipic acid and 2.83 Kg (25 mol) of caprolactam were added to prepare a slurry-like polymerization stock solution, which was transferred to an autoclave and purged with nitrogen, sealed, and heated while stirring to raise the internal temperature. 200
℃, and the internal pressure was 13Kg/cm ² . Next, water is distilled out while maintaining this pressure, and the internal temperature is gradually increased to bring the internal pressure to normal pressure.Finally, after maintaining the internal temperature at 280℃ for 1 hour, nitrogen is pressurized and the autoclave is placed. The copolyamide was discharged from a nozzle, cooled, and chipped to obtain a copolymer with a relative viscosity of 2.24 and a glass transition point of 124°C. Several batches of the chips thus obtained were put into ion-exchanged water and extracted four times for 4 hours each at 80°C.Finally, the water was drained off and the chips were vacuum-dried. This was used as the B component, and nylon 6 chips with a relative viscosity of 3.30 were mixed as the A component in various proportions (weight ratio), melt extruded at 285℃ using a T-die, cooled with a cooling roll at 35℃. A stretched film with a thickness of about 220 μm and a width of about 25 cm was obtained. This film is 110mm in diameter at a speed of 2m/min.
The first
After longitudinal stretching under the conditions shown in the table, the film was stretched horizontally by running through a film transverse stretching tenter having a width of about 3 m and a length of about 11 m, and heat set under tension at 200° C. for 15 seconds in the tenter.

[Table] In the evaluation of the stretchability shown in the table, the number of breaks during transverse stretching per 8 hours of operating time was 1 or less as ○, 2 times as △, and 3 times or more as ×. Comparative Example 2 Only the A component of Example 1 was prepared using the same equipment as Example 1,
Although the film was stretched sequentially using this method, it was not possible to obtain a uniform stretched film because there were many breaks during the transverse stretching. Comparative Examples 3 and 4 A copolymer with a relative viscosity of 3.12 and a melting point of 202°C obtained from 85 moles of caprolactam, 5 moles of hexamethylene diammonium adipate, and 10 moles each of hexamethylene diamine and terephthalic acid was used as the B component, and in Example 1 The used nylon-6 was mixed and melt-extruded using the A component to prepare an unstretched film under the same conditions as in Example 1, and then sequential stretchability was compared under the conditions shown in Table 2.
As a result, sequential stretchability could not be obtained even when 30 parts by weight of component B was mixed.

[Table] Example 2 A 90/10 mixture of A component polyamide and B component polyamide prepared in the same manner as in Example 1 was heated and melted at a temperature of 270°C using an extruder with a diameter of 20 mm having a T-die. An unstretched film with a thickness of 250 μm was obtained by extrusion on a cooling roll adjusted to . This film was sequentially biaxially stretched by 3.5 times in both longitudinal and transverse directions at a temperature of 90°C using a TMLONG film stretching tester, and then heat-set at a temperature of 200°C for 30 seconds to obtain a uniform and transparent biaxially stretched film. Ta. The physical properties of this film are shown in Table 3. Comparative Example 5 For comparison, only nylon 6 (ηr=3.10) was melt-extruded in the same manner as in Example 2, and then sequentially biaxially stretched, but the film broke during stretching or the stretched film was unstretched. It was not possible to obtain a uniform film because some portions remained unevenly.
Therefore, Table 3 shows the physical properties of a film obtained by simultaneously biaxially stretching 3.5 times each in both longitudinal and transverse directions at a temperature of 90°C and then heat-setting at a temperature of 200°C for 30 seconds.

[Table] Example 3 In the same manner as in Example 1, 35 mol of hexamethylene diamine, 25 mol of isophthalic acid, adipic acid, 11
An aqueous dispersion containing 65 moles of caprolactam and caprolactam was polymerized to obtain a copolymer with a relative viscosity of 2.11 and a melting point of about 190°C. This was used as a component B, and nylon 6 having a relative viscosity of 3.30 was used as a component A, and a mixed chip was prepared at a weight ratio of B:A=20:80. This was carried out using the same device as in Example 1.
When the film was biaxially stretched using this method, it showed good successive biaxial stretching properties. Example 4 An aqueous dispersion consisting of 70 moles of hexamethylene diamine, 15 moles of terephthalic acid, 56 moles of adipic acid and 30 moles of caprolactam was polymerized in the same manner as in Example 1, resulting in a copolymer with a relative viscosity of 2.15 and a melting point of about 235°C. Obtained union. This was used as a component B, and nylon 6 having a relative viscosity of 3.30 was used as a component A, and a mixed chip was prepared at a weight ratio of B:A=20:80. When this was biaxially stretched using the same equipment and method as in Example 1, it showed good successive biaxial stretching properties.

Claims (1)

[Scope of Claims] 1 (a) 3 to 80 mol% of caprolactam (b) Number of carbon atoms: 2
~12 or more aliphatic diamines and 4 to 36 carbon atoms
(c) 3 to 80 mol% of polyamide-forming units consisting of one or more aliphatic dicarboxylic acids and (c) one or more aliphatic or alicyclic diamines and an aromatic dicarboxylic acid or/and alicyclic dicarboxylic acid. 3 to 90 mol% of polyamide forming units consisting of one or more
3 to 50 parts by weight of a copolyamide (component B) having polymer constituent units of (a), (b), and (c) in the total amount of resin,
Aliphatic polyamide (component A) is 97 to 50% of the total resin amount.
Polyamide-based stretched film consisting of a polymer mixture with parts by weight. 2. The polyamide-based stretched film according to claim 1, wherein the film is biaxially stretched in directions perpendicular to each other. 3 Film has a breaking strength of 17Kg/mm2 or ^more , 8Kg
Impact strength of cm/25μ or more, 2×10 ^-12 cc・cm/cm ²・se
The polyamide-based stretched film according to claim 1 or 2, which has an oxygen permeability coefficient of c·cmHg or less. 4 (a) 3 to 80 mol% caprolactam (b) 2 carbon atoms
~12 or more aliphatic diamines and 4 to 36 carbon atoms
(c) 3 to 80 mol% of polyamide-forming units consisting of one or more aliphatic dicarboxylic acids and (c) one or more aliphatic or alicyclic diamines and an aromatic dicarboxylic acid or/and alicyclic dicarboxylic acid. (a) 3 to 90 mol% of polyamide structural units consisting of one or more types;
A mixture of 3 to 50 parts by weight of a copolymerized polyamide (component B) having polymer constituent units of (b) and (c) based on the total amount of resin, and 97 to 50 parts by weight of aliphatic polyamide (component A) based on the total amount of resin. After melting and forming into an unstretched film,
A method for producing a stretched polyamide film, which comprises stretching in at least one direction. 5. The method for producing a stretched polyamide film according to claim 4, wherein the stretching step is to sequentially stretch an unstretched film in directions perpendicular to each other.