JPH023819B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a copolymerized polyamide film for packaging,
More specifically, the present invention relates to a copolyamide film for packaging with improved blocking resistance in hot water. [Problems to be solved by the conventional technology and the invention] Polyamide film has excellent transparency, pinhole resistance, gas barrier properties, heat resistance, oil resistance, thermoformability, etc., so it is mainly used for food packaging. used in In particular, polyamide film is attracting attention as an important constituent material for coextruded films with high performance. Nylon 6 film is mainly used for this purpose, but recently copolymerized polyamide films such as nylon 6/66 and nylon 6/12 have been gaining popularity. The reason is that the copolyamide film has excellent transparency, low-temperature impact resistance, and thermoformability. However, this copolyamide film has poor slip properties and is prone to blocking. For this reason, various slip agents and antiblocking agents are added to prevent blocking, and it is known that the addition of inorganic fine particles such as silica and talc is particularly effective. However, in the case of copolymerized polyamide films, troubles due to blocking in hot water have recently occurred. Moreover, this blocking easily occurs in water at a low temperature of around 60°C, even under a low load. For example, after filling and sealing a packaging bag made from a coextruded film of copolyamide (outer layer)/adhesive layer/polyolefin (inner layer),
When the bags are piled up and treated in hot water, the outer copolymerized polyamide films of the packaging bag will block each other. If this blocked coextrusion packaging bag is forcibly peeled off, the bag will break due to the strong blocking adhesion, causing serious trouble.
Blocking in hot water, which is characteristic of this copolyamide film, cannot be prevented even by adding inorganic fine particles such as silica or talc. [Means for Solving the Problems] As a result of repeated research to improve the drawbacks of such copolyamide films, the present inventors have found that copolymerization in hot water is possible by blending a specific amount of bisamide. The inventors have discovered that the blocking resistance of polyamide films can be improved, and have arrived at the present invention. That is, in the present invention, based on 100 parts by weight of copolymerized polyamide, or (In the formula, R ¹ represents an alkylene group, an arylene group, or an arylene dialkylene group, and R ² and R ³
represents an alkyl group, an aryl group, an aralkyl group, or a cycloalkyl group, and R ⁴ and R ⁵ represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a cycloalkyl group. ) is a copolymerized polyamide film for packaging containing 0.1 to 0.5 parts by weight of bisamide. Specific examples of the copolyamide in the present invention include nylon 6/66, nylon 6/12, nylon 6/610, nylon 6/6T (T: terephthalic acid component), nylon 6/66/12, and nylon 6/66. /
610 etc. As R ¹ in formula () or formula (),
C1-C12 alkylene groups such as methylene, ethylene, trimethylene, tetramethylene, hexamethylene, octamethylene, decamethylene, dodecamethylene, etc., arylene such as phenylene, naphthylene, etc. or an arylene dialkylene group such as a xylylene group in which two hydrogen atoms of an aromatic hydrocarbon are substituted with two alkylene groups. ^R2 and ^R3
Examples include ethyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group,
Decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, heneicosyl group,
Examples include alkyl groups having 2 to 30 carbon atoms such as docosyl group, heptacosyl group, and triaconcyl group, aryl groups such as phenyl group and naphthyl group, aralkyl groups such as benzyl group, and cycloalkyl groups such as cyclohexyl group. It will be done. These R ²
The groups represented by R ³ and R 3 may contain a small amount of unsaturated bonds, and R ² and R ³ may be the same group or different groups. ^R4 and ^R5
As hydrogen atom or methyl group, ethyl group,
1 to 12 carbon atoms, such as propyl, butyl, hexyl, octyl, decyl, and dodecyl
alkyl groups such as phenyl groups, aryl groups such as naphthyl groups, aralkyl groups such as benzyl groups,
Examples include cycloalkyl groups such as cyclohexyl groups, and R ⁴ and R ⁵ may be the same group or different groups. These R ¹ to R ⁵ groups may have a branched chain. The bisamide represented by the above general formula () is
Alkylene diamines such as ethylenediamine, propylene diamine, butylene diamine, hexamethylene diamine, octamethylene diamine, decamethylene diamine, dodecamethylene diamine; arylene diamines such as phenylene diamine and naphthylene diamine; arylene dialkylene diamines such as xylylene diamine; diamines such as stearic acid, hexanoic acid, octanoic acid, decanoic acid,
Alkylene bis fatty acid amide, arylene bis fatty acid amide, arylene bis fatty acid amide obtained by reaction with fatty acids such as lauric acid, myristic acid, palmitic acid, arachidic acid, behenic acid, oleic acid, elaidic acid, montanic acid, etc. Refers to all amides, but the most representative ones are N,N'-methylene bisstearic acid amide (hereinafter referred to as MBS), N,
N′-ethylene bisstearamide (hereinafter referred to as
It's called EBS. ). Bisamides represented by the general formula () include alkylamines such as ethylamine, methylamine, butylamine, hexylamine, decylamine, pentadecylamine, octadecylamine, and dodecylamine; arylamines such as aniline and naphthylamine; benzylamine, etc. aralkylamines; cycloalkylamines such as cyclohexylamine; monoamines such as terephthalic acid, p-phenylene dipropionic acid, succinic acid,
Refers to everything obtained by reaction with dicarboxylic acids such as adipic acid, among others, N,
N'-dioctadecyl terephthalic acid amide, N,
N'-diethylene-dioctadecyl terephthalic acid amide, N,N'-dioctadecyl-p-phenylene dipropionic acid amide, N,N'-dioctadecyl succinic acid amide, N,N'-dioctadecyl adipic acid amide, Dioctadecyl dibasic acid amide such as N,N'-dimethyl-dioctadecyl adipate amide is exemplified as a typical example. These bisamides are used alone or as a mixture, regardless of whether they are compounds represented by the general formulas () or (). The amount of the bisamide added in the present invention is 0.1 to 0.5 parts by weight, preferably 0.13 to 0.3 parts by weight, based on 100 parts by weight of the copolyamide. If the amount added is less than the above range, it will be difficult to obtain the effects of the present invention, and if it is added in a larger amount, it will cause problems such as poor biting during extrusion, which is not preferable. There are no particular restrictions on the method of adding the bisamide to the copolymerized polyamide, and well-known methods may be employed. However, the method of applying blended oil to the surface of the polyamide pellets and then adhering the bisamide powder thereto is as follows: It is preferable because it can be blended uniformly.
Furthermore, additives such as antistatic agents and colorants may be added depending on the intended use. The copolymerized polyamide film for packaging of the present invention is
Although it can be obtained using ordinary molding equipment, it is preferable to use a rapid compression type extruder screw. In the packaging copolymer film of the present invention, it is necessary to add 0.1 part by weight or more of bisamide to 100 parts by weight of the copolyamide.
If a slow compression type screw with a small compression ratio and a large number of ridges in the compression section is used, it may cause poor biting. [Effect of the invention] The copolymerized polyamide film for packaging of the present invention has the following properties:
It makes full use of the characteristics of copolyamides, such as transparency, impact resistance, and thermoformability, and can prevent blocking in hot water, making it especially suitable for food packaging films. [Example] Next, Examples and Comparative Examples of the present invention will be given. (1) Film molding Molding was performed using a T-die film molding device. The extruder has a diameter of 40 mm, and the T-die is a coat hanger type (width 450 mm). The molding conditions are
The extrusion temperature was 250°C, the lip opening was 0.4mm, the chill roll temperature was 50-60°C, the take-up speed was 3m/min, and the film thickness was 100μ. (2) Evaluation of blocking properties in hot water The formed film was pasted on a SUS board as shown in Figure 1, stacked and held horizontally in a constant temperature water bath, and the load was 75g (SUS board's own weight) and the immersion time was 5
I soaked it at various temperatures for 1 minute. Take it out and leave it to cool to room temperature, then peel it off by hand.
Blocking property was evaluated according to the following criteria. ○: No blocking. Δ: Blocking occurs partially. ×: Strong blocking occurs, and the bag will break if it is forcibly peeled off. (3) Film transparency (haze) Haze was measured according to ASTM D 1003-61 using an SM color computer manufactured by Suga Test Instruments. Comparative Example 1 A film was formed using 6/66 copolymerized polyamide pellets (hereinafter referred to as 6/66) having a relative viscosity of 4.4 and a melting point of 195°C. Table 1 shows the haze and blocking resistance in hot water of the film thus obtained. Blocking occurs even at temperatures as low as 60°C, and strong blocking occurs at temperatures above 70°C, and the bag will break if it is forcibly peeled off. In addition, dry heat 100
Blocking does not occur even if a similar experiment is performed at °C. Comparative Examples 2 to 3 6/66 was dry blended with EBS in the proportions shown in Table 1, formed into a film, and evaluated in the same manner as in Comparative Example 1. The results are shown in Table 1. It can be seen that although the blocking resistance is slightly improved compared to Comparative Example 1, it is not sufficient. Examples 1 to 3 Film molding and evaluation were performed in the same manner as in Comparative Examples 1 to 3, except that the amount of EBS added was 0.1% by weight or more. (Table 1). It can be seen that blocking in hot water can be effectively prevented by adding 0.1% by weight or more of EBS. Moreover, transparency (haze)
has little effect on It also shows similar blocking resistance even in a 15% by weight ethanol aqueous solution. When 0.13% by weight or more of EBS is added, blocking does not occur even in boiling water or under heavy load (Examples 2 and 3). Example 4 Example 3 was repeated except that MBS was used instead of EBS. MBS also shows similar blocking resistance (Table 1). Comparative Example 4 Inorganic slip agent talc [Nippon Talc Co., Ltd.] on 6/66
A film was formed in the same manner as in Comparative Example 1 using pellets prepared by dry blending 0.2% by weight of product: Micron Ace L-1 (trade name), and the blocking resistance in hot water was examined. (Table 1) It can be seen that even if an inorganic slip agent talc is added, it is not very effective in preventing blocking in hot water. Example 5 Comparative Example 4 was repeated except that 0.15% by weight of EBS was dry blended. The results are shown in Table 1, and no blocking occurred in hot water. Comparative Example 5 0.15% by weight of stearamide instead of EBS
Example 3 was repeated except that it was dry blended.
The results are shown in Table 1, and blocking in hot water could not be prevented. Comparative Example 6 Example 3 was repeated except that 0.15% by weight of erucamide was dry blended in place of EBS. The results are shown in Table 1, and the results were similar to those of Comparative Example 5. Comparative Example 7 Low molecular weight polyethylene instead of EBS [Hoechst Japan Co., Ltd. product: trade name Hoechst Wax]
Example 3 was repeated except that 0.15% by weight of dry blended PA190] was added. The results are shown in Table 1, and the results were similar to those of Comparative Example 5. Example 6 EBS was added to 6/12 copolymerized polyamide pellets (hereinafter referred to as 6/12) with a relative viscosity of 2.5 and a melting point of 190°C.
A dry blend of 0.15% by weight was carried out, and a film was formed under the same conditions as in Comparative Example 1. The results are shown in Table 1, and no blocking occurred in hot water. Comparative Example 10 Nylon 6 pellets (hereinafter referred to as 6) having a relative viscosity of 4.4 and a melting point of 220°C were formed into a film under the same conditions as in Comparative Example 1. The results are shown in Table 1, and no blocking occurred at all. Thus, it can be seen that blocking in hot water is a phenomenon unique to copolyamides. 【table】

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a formed film attached to a SUS plate and stacked on top of each other in order to evaluate blocking properties in hot water in Examples and Comparative Examples. 1... Sample film, 2... Cellotape (110 x 140 (mm)), 3... SUS board (100 x 100 x 1
(mm)).

[Claims]

1 A polymer obtained by polymerizing substantially equimolar amounts of biphenyltetracarboxylic dianhydride and an aromatic diamine compound in the presence of water, the logarithmic viscosity of the polymer (30°C, 0.5 g/ This is a composition in which polyamic acid having a concentration of 0.1 to 1.5 (N-methylpyrrolidone) is dissolved in an organic polar solvent in an amount of 5 to 40% by weight, and the free water content in the composition is 0.1 to 1.5. Measured by magnetic resonance spectroscopy
A polyamic acid solution composition characterized in that the content is 0.5% by weight or less. 2 Using substantially equal moles of biphenyltetracarboxylic dianhydride and aromatic diamine compound,
Polyamic acid is produced by reacting in an organic polar solvent containing 0.5 to 40 moles of water per mole of the acid dianhydride at a reaction temperature of 100°C or less, and the reaction solution becomes a homogeneous solution. After cooling, free water is removed from the reaction solution, and the content of free water in the reaction solution is determined to be 0.5% by weight or less as measured by nuclear magnetic resonance spectroscopy, and the logarithmic viscosity (30℃, 0.5
1. A method for preparing a polyamic acid solution composition, which comprises dissolving 5 to 40% by weight of polyamic acid having a content of 0.1 to 1.5 (g/100ml N-methylpyrrolidone).