JPH07138471A - Polyamide resin composition and packaging film prepared therefrom - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in the oxygen barrier resistance, transparency and slipperiness under high humidity of the film prepared therefrom, useful for packaging films for high water content foods, etc., by incorporating a polyamide resin with each specified amount of silica and talc. CONSTITUTION:This resin composition is obtained by incorporating (A) 100 pts.wt. of a polyamide resin such as nylon 6 or nylon 6-66 copolymer resin with (B) 0.03-0.5 pts.wt. of silica pref. 80-350ml/100g in oil absorption and (C) 0.01-0.07 pts.wt. of talc pref. 30-50ml/100g in oil absorption.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyamide resin composition for film forming. More specifically, the present invention relates to a polyamide resin composition for forming a polyamide film, which is prepared by combining specific silica and talc and is particularly excellent in slipperiness under high humidity.

[0002]

2. Description of the Related Art Polyamide films are superior in oxygen barrier properties, tough strength and flexibility to biaxially oriented polypropylene films and biaxially oriented polyester films.
Because of its features such as heat resistance, transparency, and that it can be used in a wide temperature range, it is mainly used as a food packaging material by utilizing these features.

In the technical field of such a polyamide film, if the film has poor slipperiness, the film may be caught during bag making, or ink misalignment may occur during multicolor printing. It is a very important characteristic in terms of productivity, quality and commercial value. In particular, in the packaging material field of foods containing a large amount of water such as konjac and pickles, poor slipperiness under high humidity causes bag feeding failure and facilitates filling of such water-rich contents. It cannot be performed and stable continuous operation becomes difficult.

Various methods have heretofore been tried to improve the slipperiness of such a polyamide film. For example, a method of adding an inorganic filler (Japanese Patent Publication No. 54-474).
1) and a method of blending polyethylene (Japanese Patent Publication No. 53-4)
5226) etc. have been proposed

[0005]

However, in the former method of incorporating the inorganic filler, there is a possibility that the transparency, which is a characteristic of the polyamide film, is lowered and the commercial value is lost. Therefore, the addition amount is significantly limited, and sufficient slipperiness cannot be exhibited. In particular, the improvement of slipperiness under high humidity was insufficient.

Further, when the surface activity of the inorganic particles is high, the thermal stability of the polyamide resin becomes poor, fish eyes and die lines are apt to occur, the appearance becomes poor, and continuous stable productivity becomes a problem. In particular, silica-based particles have such a strong tendency that the appearance defects such as die lines and fish eyes are liable to occur, and therefore care must be taken when using them. on the other hand,
The method of blending polyethylene is also recognized to greatly reduce the transparency of the film, and at the same time, it has the drawback of causing a decrease in strength.

Therefore, it has not been easy to industrially obtain a polyamide film having excellent slipperiness without causing deterioration of transparency, deterioration of strength, poor appearance and the like.

[0008]

[Means for Solving the Problems] As a result, the inventors have conducted earnest studies to develop a film having excellent slipperiness, particularly slipperiness under high humidity, while ensuring the transparency of the polyamide film. The inventors have found that such an object can be achieved by blending a certain amount of silica and talc in a polyamide resin, and particularly by using silica and talc having a specific oil absorption amount together, and arrived at the present invention.

That is, the gist of the present invention is a resin composition obtained by mixing 0.03 to 0.5 part by weight of silica and 0.01 to 0.07 part by weight of talc with 100 parts by weight of a polyamide resin. The present invention relates to a polyamide film. The present invention will be described in detail below. As the polyamide resin used in the present invention, a polyamide resin obtained by polycondensation of a lactam having 3 or more membered rings, a polymerizable ω-amino acid, a dibasic acid and a diamine, or the like can be used. Specifically, ε-caprolactam, aminocaproic acid, enanthlactam, 7-aminoheptanoic acid, 1
Polymers such as 1-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone and α-piperidone, diamines such as hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine and metaxylenediamine, and terephthalic acid , Isophthalic acid,
Polymers or copolymers obtained by subjecting dicarboxylic acids such as adipic acid, sebacic acid, dodecane dibasic acid, glutaric acid, etc. to polymerisation, for example nylon 4, 6,
7, 8, 11, 12, 6/6, 6/10, 6/11, 6
・ 12, 6T, 6/6 ・ 6, 6/12, 6 / 6T, 6I
/ 6T and the like.

Of these, nylon 6 or nylon 6/6/6 copolymer resin is particularly suitable in terms of the thermal and mechanical properties of the obtained film. Regarding the relative viscosity (ηrel) of the polyamide resin used,
According to JIS-K-6810, 98% sulfuric acid concentration 1%,
A range of 2 to 6, preferably 2 to 5 as a value measured at a temperature of 25 ° C. is suitable. If the relative viscosity is too low, the mechanical strength of the obtained film is low and it cannot be used. On the other hand, if the relative viscosity is too high, the extrusion pressure and torque are too high, and molding becomes impossible.

The polyamide resin of the present invention has a water extraction amount of 1% or less, preferably 0.5% or less, which is measured according to the method for measuring the content of low molecular weight substances specified in JIS-K-6810. Is preferred.
When the amount of water extracted is large, the oligomer component is remarkably attached to the vicinity of the die, and the die continuous line and fish eyes are generated by these adhered substances, so that the industrial continuous productivity is deteriorated.

The silica used in the present invention is not particularly limited, and commercially available ones can be used, but preferably,
The oil absorption measured according to JIS-K-5101 is 80.
What is in the range of up to 350 ml / 100 g is used. If the amount of oil absorption is too large, the dispersibility of silica in the polyamide film becomes poor, and fish eyes are easily generated due to secondary aggregates, which is not preferable. on the other hand,
If the oil absorption is too small, voids and stretching breakage during stretching increase, which is not preferable. In the present invention, it is preferable to use particles obtained by classifying and removing particles having a particle diameter of 10 μm or more.

The silica suitable for the present invention may be so-called wet silica or dry silica. Further, by subjecting the surface to a known method such as a silane coupling agent or a titanium coupling agent, better dispersibility can be obtained, and at the same time, the transparency of the film is improved.
The method of this surface treatment is not particularly limited, but for example, the method described in JP-A-63-251460 can be used.

The silica content is 100% polyamide resin.
The amount is 0.03 to 0.5 part by weight, and particularly preferably 0.1 to 0.25 part by weight. If the amount added is too small, the improvement of the slipperiness of the film becomes insufficient, which is not preferable. On the other hand, if the addition amount is too large, it may cause deterioration of transparency and fish eyes. The talc is not particularly limited, and commercially available ones can be used, but JIS-K-51
Oil absorption measured according to method 01 is 30 to 50 ml / 10
Those in the range of 0 g are preferable. If the oil absorption is too large, the dispersion will be poor like silica, and if it is too small, voids and stretch breaks will occur. In the present invention, it is preferable to use particles obtained by classifying particles of 10 μm or more and removing them.

The blending amount of talc is 100% polyamide resin.
The amount is 0.01 to 0.07 part by weight, and particularly preferably 0.01 to 0.06 part by weight. If the amount added is small, the slipperiness under high humidity (85% RH) is not improved, and conversely, if it is too large, the transparency deteriorates and the slipperiness under high humidity also deteriorates. The present invention is characterized in that the specific amount of silica and talc described above are used together. This is for ensuring the slipperiness, particularly the slipperiness under high humidity, while ensuring the transparency. That is, in order to improve slippage under high humidity with silica alone or talc alone, for example, each of them can be reduced to, for example, 0.
It is necessary to add a large amount of 5 parts by weight or 0.08 parts by weight or more, but if such a large amount is added, problems such as deterioration of transparency and generation of fish eyes occur, which is not practical.

The silica and talc may be added to the polyamide resin by adding during polymerization of the polyamide resin, or by kneading the polyamide resin in high concentration in advance using a uniaxial or biaxial extruder. A so-called masterbatch method in which this is diluted at the time of molding is used, a kneading method in which it is kneaded into a polyamide resin in advance at the additive concentration used in molding, and a dry blending method in which a predetermined amount is added to the polyamide resin during molding At this time, a known spreading agent may be used if necessary. Also,
Silica and talc may be added by different methods.

Polyamide resins containing these inorganic fillers include various lubricants such as bisamide compounds, hindered phenols, phosphoric acid esters, and phosphorous acid ester-based materials as long as the properties of the film are not impaired. You may mix and use additives, such as an antioxidant, a weather resistance improving agent, a mold release agent, an antistatic agent, an antiblocking agent, a dye, and a pigment. Bisamide compounds are particularly effective and useful as organic lubricants.

The polyamide film of the present invention can be formed by a known method. For example, a melt of the resin raw material is continuously extruded from a T-die and is formed into a film while being cooled by a casting roll, a T-die method is continuously extruded from an annular die, and water is contacted and cooled. A water-cooled inflation method, an air-cooled inflation method of extruding from an annular die and cooling with air is also used.

Further, a multilayer film can be obtained by a coextrusion method in which other raw materials are simultaneously extruded by these molding methods. As a method for forming a raw material for a stretched film, a T-die method and a water-cooled inflation method are particularly excellent in continuous stretchability. Further, the polyamide film of the present invention can be stretched, and a known method can be applied as a stretching method. For example, a film formed by the T-die method uses a roll method for longitudinal stretching, and a so-called sequential biaxial stretching method using a tenter method when stretching in the transverse direction, a tubular film formed by an annular die. In addition to the above-mentioned sequential biaxial method, a tubular drawing method that allows simultaneous drawing in the machine and transverse directions is used.

The polyamide film of the present invention can be used by laminating it with another film such as a polyolefin film. The method for laminating is not particularly limited, but when coextruding, each layer can be simultaneously stretched (costretched) in the same manner for a coextruded film. The polyamide film of the present invention thus obtained can be used after corona treatment on one side or both sides for improving printability and laminating property.

[0021]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. In addition, evaluation of various physical properties in the following examples was performed as follows. (1) Transparency The haze value was evaluated using a haze meter manufactured by Tokyo Denshoku Co., Ltd. (2) Sliding property The static friction coefficient was measured by a parallel displacement method under the conditions of 23 ° C. and relative humidity of 65% and 85%. (3) Appearance of Film The film was cut into a square of 300 mm × 300 mm, and the portion was visually observed to determine whether a die line was generated and the number of fish eyes (FE) having a size of 40 μm or more.

Examples 1 to 3 and 5 and Comparative Examples 1 and 3 60 kg of ε-caprolactam, 1.2 kg of water, and 200 ml of an autoclave in an amorphous wet type having an oil absorption of 310 ml / 100 g according to the JIS-K-5101 method. Synthetic silica was charged so as to have the addition amount shown in Table 2 when polyamide resin chips were used.

The autoclave was sealed in a nitrogen atmosphere, the temperature was raised to 260 ° C., the reaction was carried out under pressure for 2 hours while stirring, then the pressure was gradually reduced to 100 Toor, and the pressure was further reduced for 2 hours. The reaction was carried out. Then, nitrogen was introduced into the autoclave to blow it to an upper pressure, stirring was stopped, and the polyamide resin was extracted as a strand and made into chips.

Then, the obtained polyamide resin chips were put into boiling water to extract and remove unreacted monomers, and then vacuum dried. The relative viscosity of the obtained polyamide resin was measured and found to be 4.5. Talc of the combination shown in Table 1 was added to 100 parts by weight of this polyamide resin, and the addition amount shown in Table 2 was added to obtain a stretched raw fabric having a thickness of 135 μm by a water-cooled inflation method. The obtained film was heat-set at 80 ° C. using a biaxial stretching machine manufactured by Long Co. to obtain a biaxially stretched film having a thickness of about 15 μm.

Examples 4, 6 and Comparative Examples 2, 4, 5 100 parts by weight of commercially available nylon 6 resin (Novamid 1020: Novamid is a registered trademark, manufactured by Mitsubishi Kasei Co., Ltd.),
The inorganic fillers shown in Table 1 were added in the amounts shown in Table 2, and a stretched raw fabric having a thickness of 135 μm was formed by a water cooling inflation method. Then, the obtained film was simultaneously biaxially stretched at a strain rate of 20000% / min under a condition of 80 ° C. using a biaxial stretching machine manufactured by Long Co., and further heat set at 210 ° C. to have a thickness of about 1
A 5 μm biaxially stretched film was obtained. Table 2 shows the evaluation results of various physical properties of the obtained film.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

According to the present invention, it is possible to obtain a film having excellent slipperiness especially under high humidity while ensuring the transparency of the polyamide film having excellent oxygen barrier property.
Therefore, the present invention is a very useful technique especially in the field of packaging materials for foods containing a large amount of water.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoaki Kinmasa 370 Enzo, Chigasaki City, Kanagawa Mitsubishi Kasei Co., Ltd. Chigasaki Plant

Claims (3)

[Claims] 1. To 100 parts by weight of a polyamide resin, 0.03 to 0.5 parts by weight of silica and 0.01 to 0.
A polyamide resin composition for film forming, comprising 07 parts by weight. 2. A silica 0.03 having an oil absorption of 80 to 350 ml / 100 g with respect to 100 parts by weight of a polyamide resin.
To 0.5 parts by weight and 0.01 to 0.07 parts by weight of talc having an oil absorption of 30 to 50 ml / 100 g, a polyamide resin composition for film molding. 3. A packaging film having excellent slipperiness, which comprises the polyamide resin composition according to claim 1 or 2.