JP2821243B2 - Manufacturing method of laminated biaxially stretched film - Google Patents

Description

The present invention relates to a method for producing a laminated biaxially stretched film, and more particularly, to a method for producing a polyamide laminated biaxially oriented film using a sequential biaxial stretching method. It is about the method.

[Conventional technology]

m- and / or p-xylylenediamine and carbon number 6 to
A film of an aromatic polyamide (hereinafter abbreviated as A) containing at least 70 mol% of polyamide constituent units composed of α and ω aliphatic dicarboxylic acids in the molecular chain has excellent oxygen gas barrier properties with little humidity dependency. And excellent in transparency and oil resistance. However, it is inferior in bending pinhole resistance, and its use has been limited.

On the other hand, an aliphatic polyamide (hereinafter abbreviated as B) film is excellent in mechanical properties such as tensile strength and pinhole resistance, but has a sufficient oxygen gas barrier property when used in foods, pharmaceuticals, chemicals, and the like. Not really.

Therefore, a biaxially stretched film including a layer containing (A) as a main component and a layer containing (B) as a main component has been proposed.

[Problems to be solved by the invention]

However, production of the above-described polyamide-laminated biaxially stretched film is not always easy.

For example, JP-A-56-49269 discloses a production method by a sequential biaxial stretching method which is industrially advantageous because it is suitable for mass production. In order to ensure this, it is essential that the total number of layers (A) and (B) is eight or more.

As another production method, there is a method described in JP-A-57-51427, but this method is a production method by an inflation method, and is not an industrially advantageous production method.

The invention provides a relatively low total number of layers and mechanical properties,
An object of the present invention is to provide a method for producing a polyamide laminated biaxially stretched film having good oxygen gas barrier properties by a sequential biaxial stretching method.

[Means for solving the problem]

The present inventors have conducted intensive studies in view of the above-mentioned circumstances, and as a result, with respect to a polyamide laminated film having a total number of layers of 5 layers or less, a sufficient sequential biaxial The knowledge that stretchability was ensured was obtained, and the present invention was completed.

That is, the gist of the present invention is to provide a polyamide structural unit comprising m- and / or p-xylylenediamine and an α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in a molecular chain at 70 mol%.
A non-oriented laminated film having a total number of layers of 5 or less is obtained by extruding in a molten state two or more raw material polyamides selected from a raw material group consisting of an aromatic polyamide, an aliphatic polyamide and a mixed polyamide containing the same. Stretching temperature of non-oriented laminated film is 40 ~ 80 ℃, average deformation rate is 10,000%
The film is stretched longitudinally 2.5 to 3.7 times under the conditions of / min or more, the stretched film is stretched at a temperature of 55 to 100 ° C, and the average deformation rate is 300 to 10,000.
The film was stretched 3.0 to 5.0 times under the condition of 00% / min.
A method for producing a laminated biaxially stretched film, characterized in that a heat treatment is performed under the condition that the lower temperature is lower by 5 ° C. and the upper limit is 5 ° C. lower than the melting point of the aromatic polyamide raw material.

 Hereinafter, the present invention will be described in detail.

 First, the raw material polyamide will be described.

In the present invention, m- and / or p-xylylenediamine which is one of the raw material polyamides and α, having 6 to 12 carbon atoms,
As the aromatic polyamide containing a polyamide constituent unit composed of ω aliphatic dicarboxylic acid in an amount of 70 mol% or more in the molecular chain, the following may be mentioned.

(1) Homopolymers such as poly-met-xylylene adipamide, poly-met-xylylene piperazide, poly-met-xylylene azeramid, poly-para-xylylene azeramide, poly-para-xylylene decanamid (2) Copolymers such as poly-meta-xylylene / para-xylylene adipamide, poly-met-xylylene / para-xylylene piperamide, poly-met-xylylene / para-xylylene azeramide, poly-met-xylylene / para-xylylene sepacamide (3) A copolymer comprising 70% by mole or more of the above-mentioned homo- or copolymer component and another polyamide component (4) A polymer 5 compatible with the above-mentioned homo- or copolymer component In the above, other polyamide constituents include hexamethylenediamine, 2,2,4-trimethylhexa. Aliphatic ring- or heteroatom-containing diamines such as aliphatic diamines such as methylene diamine, piperazine bispropylamine and neopentyl glycol bispropylamine, and fatty acid dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid, and terephthalic acid An aromatic dicarboxylic acid such as isophthalic acid, a polyamide component obtained from a cycloaliphatic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid, a lactam such as ε-caprolactam,
and ω-aminocarboxylic acids such as ε-aminocarboxylic acid.

In the above description, as the polymer compatible with the polymer, other polyamide constituents or other compatible thermoplastic resins are intended. If the amount of the polymer to be mixed exceeds 20% by weight, the gas barrier property of the obtained laminated stretched film is undesirably reduced.

And, in the aromatic polyamide raw material, m- and / or p-xylylenediamine and α, having 6 to 12 carbon atoms,
In the case of a polymer having less than 70 mol% of the polyamide constituent unit composed of the ω aliphatic dicarboxylic acid in the molecular chain, the gas barrier property of the obtained laminated biaxially stretched film is reduced, which does not meet the purpose of the present invention. .

In the present invention, examples of the aliphatic polyamide include the following.

(1) Homopolymer of ε-caprolactam (homopolymer) (2) 2 to 10% by mole of ε-caprolactam as a main component
(3) Mixture of the above homopolymer and / or copolymer with 5 to 20% by weight of a polymer compatible with the above. In the above, copolymerization with ε-caprolactam Possible compounds include nylon salts of aliphatic or aromatic diamines with aliphatic or aromatic dicarboxylic acids.

Representative examples of diamines include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylenediamine, metaxylylenediamine,
Paraxylylenediamine and the like, and representative examples of dicarboxylic acids include adipic acid, sebacic acid, corkic acid, glutaric acid, azelaic acid, β-methyladipic acid, terephthalic acid, isophthalic acid, decamethylenedicarboxylic acid, dodeca Examples include methylene dicarboxylic acid and pimelic acid.

Among the above-mentioned aliphatic polyamides, a homopolymer of ε-caprolactam, usually called nylon-6, is inexpensive and easily available, but it has conventionally been said that sequential biaxial stretching is difficult.

The method of the present invention can be said to be extremely advantageous industrially because such a homopolymer of ε-caprolactam can be smoothly and sequentially biaxially stretched.

In the present invention, as the mixed polyamide, a mixture of the above-mentioned aromatic polyamide and aliphatic polyamide can be used. The mixed polyamide is usually prepared by using a cut off material (hereinafter, referred to as “ear trim end material”) at the side of the film gripped by the tenter clip, a scrap, and the like, which are generated in a manufacturing process.

In addition, the raw material polyamide has large hygroscopicity,
When a material that has absorbed moisture is used, when the material is hot-melted and extruded, water vapor and oligomers are generated, which tends to hinder film formation.

Therefore, it is preferable to use a substantially anhydrous raw material having a water content of 0.1% by weight or less.

In the present invention, within the range that does not affect the properties of the film, the above-mentioned raw material polyamide, a lubricant, an antistatic agent, an antioxidant, an antiblocking agent, a stabilizer, a dye,
Various additives such as pigments and inorganic fine particles can be added.

 Next, a film forming method will be described.

In the method of the present invention, first, a substantially amorphous, non-oriented, unoriented laminated film (hereinafter referred to as “non-oriented laminated film”) is produced by a co-extrusion method.

The co-extrusion method, for example, compared to the dry lamination method, the wet lamination method, etc., can omit the previous steps such as forming a single film and applying an adhesive, so that a non-oriented laminated film can be obtained in one step, and solvent pollution and This is an excellent method that has no drawbacks such as leaving solvent odor.

As a specific example of the co-extrusion method, a multi-manifold die method, a feed block method, a multi-srod die method, and the like are known, and any of the methods can be employed in the method of the present invention.

The co-extruded non-oriented laminated film is brought into close contact with the surface of the casting roll kept at 40 ° C. or lower, preferably 35 ° C. or lower, and solidified. Known means such as an electrostatic pinning method and an air knife method can be employed as the contact means.

In the method of the present invention, the non-oriented laminated film is selected from a raw material group consisting of the aromatic polyamide (A), the aliphatic polyamide (B) and a mixed polyamide (C) thereof, and has a total number of layers of 5 or less. It is necessary to form an oriented laminated film.

A / B, A / B / A, B / A / B, A / B / C,
B / A / C, A / C / B, A / C / B / C / A, B / C / A / C / B and the like.

The non-oriented laminated film is stretched in the longitudinal direction by a roll-type longitudinal stretching machine (hereinafter, simply referred to as “longitudinal stretching”).
Is called). In the present invention, a known roll-type high-speed longitudinal stretching machine can be used.

In the longitudinal stretching, the stretching temperature is 40 to 80 ° C and the average deformation speed is 10.0
It must be performed 2.5 to 3.7 times under the condition of 00% / min or more.

If the stretching temperature is lower than 40 ° C, the film after longitudinal stretching tends to cause longitudinal stretching unevenness, and if the temperature is higher than 80 ° C, the film easily sticks to the roll surface, similarly, after the longitudinal stretching. The film tends to have longitudinal stretching unevenness, and furthermore, directional hydrogen bonding occurs in the stretching direction, and the film stretches in the next transverse direction (hereinafter simply referred to as “lateral stretching”). Uneven stretches and unstretched residual portions (unstretched portions near the tenter clips) are generated, and the film is easily torn, which is not preferable.

The above-mentioned deformation speed refers to a value calculated by the following equation (I).

In the above formula (I), each symbol has the following meaning.

V _MD : Film longitudinal deformation speed (% / min) X: Film longitudinal stretching ratio (times), obtained from U _H / U _L L: Length of longitudinal stretching section (m) _UL : Low speed roll Linear velocity (m / min) U _H : linear velocity of high-speed roll (m / min) If the deformation speed (V _MD ) is lower than 10,000% / min, During the transverse stretching, unevenness in the transverse stretching is likely to occur in the film, which is not preferable. On the other hand, when the deformation rate (V _MD ) is more than 10,000% / min, the longitudinal stretching is favorably performed, and the transverse stretching is not generated in the next transverse stretching, which is preferable. The upper limit of the deformation rate can be selected variously depending on the structure of the apparatus used, the performance, the film temperature at the start of stretching, etc.
It is good to be less than 0,000% / min.

In addition, when the film temperature at the start of stretching is low, it is preferable that the deformation speed be low within the above range, and when the film temperature is high, it is preferable that the deformation speed be high within the above range. When the deformation rate is 5,000% / min or more, the film temperature may increase slightly (10 to 20 ° C.) due to heat generation during stretching. In this case, it is necessary to cool the film as necessary. There is.

If the longitudinal stretching ratio is smaller than 2.5 times, the desired orientation effect cannot be imparted to the finally obtained film, and if it is larger than 3.7 times, the transverse stretching unevenness and unstretched residue at the next transverse stretching. It is not preferable because it is apt to occur and torn easily. The preferred longitudinal stretching ratio is 2.7 to 3.5 times.

The stretching temperature can be easily adjusted by a preheating roll, and the longitudinal stretching ratio can be easily adjusted by changing the linear velocity of a high-speed roll and a low-speed roll in a roll-type vertical stretching machine.

For transverse stretching, the stretching temperature is 55-100 ° C, and the average deformation speed is 300
It is necessary to perform 3.0 to 5.0 times under conditions of ~ 10,000% / min.

The stretching temperature (the film temperature at the end of the transverse stretching) is 55
100100 ° C., preferably 60-90 ° C., but when the deformation rate and stretching ratio of the film are high, the film temperature is selected to be higher within the above range, and when the deformation speed and stretching ratio are low, It is preferable to select a lower film temperature within the above range. When the stretching temperature is out of the range, it is difficult to perform stable transverse stretching.

The film may be heated by a method of blowing hot air, a method of installing an infrared heater, a method of combining these methods, or the like.

The above-mentioned deformation speed refers to a value calculated by the following equation (II).

In the above formula (II), each symbol has the following meaning.

V _TD: transverse deformation speed of the film (% / min) Y: a mechanical set magnification of the film (magnification), y ₂ / y ₁
Find more. y ₁ is the width of the tenter at a position where the tenter clip begins to widen, y ₂ denotes a width between tenter in the transverse stretching end position.

U: Speed of the tenter (m / min) L _r : Length of the transverse stretching section (m) When the average deformation speed (V _TD ) is lower than 300% / min, the film tends to have transverse stretching unevenness and 10,000% If it is more than / min, the film is likely to break, which is not preferable.

When the transverse stretching ratio is smaller than 3 times, the unstretched residue tends to be generated, and when it exceeds 5 times, the transversely stretched film is apt to break, which is not preferable. The preferred range of the stretching ratio is 3.
The range is 5 to 4.5 times.

Next, the biaxially stretched film has a lower limit of a temperature 110 ° C. lower than the melting point of the aliphatic polyamide raw material (B) and an upper limit of a temperature 5 ° C. lower than the melting point of the aromatic polyamide raw material (A). Heat treatment under the following conditions.

By the above heat treatment, the dimensional stability of the biaxially stretched laminated film can be improved.

The temperature conditions in the above heat treatment can be selected from the following conditions according to the properties imparted to the film finally obtained.

(1) When obtaining a hot water non-shrinkable film having a shrinkage ratio of 4% or less when immersed in boiling water for 5 minutes The lower limit of the heat treatment temperature is 55 ° C. lower than the melting point of (A). , A temperature range having an upper limit of 5 ° C. lower than the melting point of (A) is selected.

When the heat treatment is performed at a temperature lower than the above range, the hot water shrinkage of the finally obtained film is increased, and the desired hot water non-shrinkable film cannot be obtained, and the heat treatment is performed at a temperature exceeding the above range. And the surface of the film whitens,
It is not preferable because of devitrification and breakage of the film.

(2) When obtaining a hot-water shrinkable film having a shrinkage ratio of 15% or more when immersed in boiling water for 5 minutes The lower limit of the heat treatment temperature is 100 ° C. lower than the melting point of (B). A temperature range having an upper limit of 30 ° C. lower than the melting point of B) is selected.

When the heat treatment is performed at a temperature lower than the above range, the heat treatment of the film becomes insufficient, and the film naturally shrinks even when left at room temperature, and when the heat treatment is performed at a temperature exceeding the above range, the hot water shrinkage decreases, A hot water shrinkable film having a large shrinkage rate cannot be obtained.

Note that each of the above heat treatments may be performed in the above temperature range in any state of the film in a tensioned state, a relaxed state, or a state in which both are combined. In the method of the present invention, it is preferable to carry out the reaction in a relaxed state of about 3 to 15%, but of course, the present invention is not limited to this.

The laminated biaxially stretched film that has been sufficiently heat-set by heat treatment is cooled and wound up according to a conventional method.

〔Example〕

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples unless it exceeds the gist.

In the following examples, the physical properties of the obtained films were evaluated by the methods described below.

Film thickness (μm) The total thickness of the film is measured at intervals of 30 mm in the width direction of the film, and the average value is shown. The thickness was measured using a contact type thickness gauge.

Film thickness unevenness (%) A value calculated by the following equation.

(The thickness unevenness described above can be said to have good thickness accuracy if the thickness is 10% or less.) Stretching ratio (times) Draw a circle with a diameter of 30 mm on a non-stretched film with a felt pen, and the circle after stretching and the circle before stretching. And the respective lengths in the vertical direction (longitudinal direction) and in the horizontal direction (width direction) were measured, and the ratio was calculated to obtain the draw ratio.

Breaking strength (kg / mm ² ), breaking elongation (%) A test piece of 10 mm in width and 100 mm in length was prepared from the film, and an autograph (DSS-2000 type) manufactured by Shimadzu Corporation was used for this test piece. The measurement was performed under the conditions of a chuck interval of 50 mm, a pulling speed of 50 mm / min, a measurement atmosphere of 23 ° C., and a relative humidity of 40%.

Pinhole strength (kg / mm) A circular formwork with an inner diameter of 100 mm is attached to the autograph (DSS-2000) crosshead, and the sample film is tensioned and fixed to this formwork. Attach a spherical needle with a 0.5 mm diameter tip through a metal round bar to the rhodo cell attached to the, and pierce by moving the crosshead at a rising speed of 50 mm / min. The strength (g) was measured, and the value divided by the thickness (mm) of the film was defined as the pinhole resistance.

Oxygen permeability (cc / m ² · 24hrs) oxygen permeability measuring apparatus OXY-TRAN100 type (Modern Control
Was measured under the conditions of 25 ° C. and 65% RH.

Hot water shrinkage (%) First, the product film is conditioned in an atmosphere at a temperature of 23 ° C and a relative humidity of 50%, and a square marked line with a side length of 80 mm is placed on the film surface. It is drawn so as to be parallel to the vertical and horizontal directions.

Next, the sample was immersed in boiling water for 5 minutes, taken out, and then again placed in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50%.
Left for hours.

The dimensions of the square before and after immersion in boiling water were measured, and were determined by the following formula.

Here, I _M1 and I _M2 mean the lengths before and after immersion of the side along the longitudinal direction of the film, and I _T1 and I _T2 mean the lengths before and after immersion of the side along the lateral direction of the film, respectively.

The vertical hot water shrinkage and the horizontal hot water shrinkage are
For hot water non-shrinkable films, less than about 4% is desirable,
For hot water shrinkable films, about 15% or more is desirable.

The raw material polyamide used in the following examples is as follows.

<Aromatic polyamide (A)> Polymethaxylylene adipamide (Mitsubishi Gas Chemical Co., Ltd., MXD-NY) (melting point: 243 ° C.) <Aliphatic polyamide (B)> Poly-ε-caproamide (Mitsubishi Chemical Corporation) Manufactured by Novamid 1022) (melting point: 224 ° C) <Mixed polyamide (C)> A mixture of the above (A) and (B) at a mixing ratio of about 1: 2 (a biaxial mixture of B / A / B produced in Example 1) Example 1 Raw material (B) and (A) using two 65 mmφ extruders
Was heated and melted at temperatures of 260 ° C. and 270 ° C., respectively, and led to a T-die having two inlets and three manifolds.

The raw material (A) from the first extruder was guided to the central manifold, and the raw material (B) from another extruder was guided to the upper and lower manifolds. The raw material (B) was branched into two by a flow path and led to upper and lower manifolds. Then, three layers of B / A / B were laminated at the exit of the T-die and extruded into a film.

The laminated film was brought into close contact with an 800 mmφ cooling roll maintained at 35 ° C. by an electrostatic pinning method and quenched, whereby the raw material (B) layer was about 50 μm each, and the raw material (A) layer was about 50 μm.
μ, a non-oriented laminated film having a total thickness of about 150 μm was obtained.

The above non-oriented laminated film is guided to a longitudinal stretching machine composed of a plurality of rolls.
The film was longitudinally stretched at a stretch ratio of 2.9 / min.

Subsequently, the longitudinally stretched film is transferred to a tenter-type transverse stretching machine, and both ends thereof are gripped with tenter clips, and transverse stretching is performed under the conditions of a stretching temperature of 80 ° C, an average deformation speed of 3000% / min, and a stretching ratio of 3.2 times. Was.

Subsequently, a heat treatment was performed at 200 ° C. while holding the transversely stretched film with a tenter clip.

The film after heat treatment, cut off both ears of the film,
Wound by winder.

The thickness of each layer of B / A / B of the obtained laminated biaxially stretched film was about 5 μm, and the total thickness was about 15 μm.

The film was produced continuously for 5 hours by the above-mentioned method, but the operation could be performed smoothly without any abnormality during the production.

Table 1 shows the details of the operating conditions and the situation at the time of stretching, and Table 2 shows the measurement results of the physical properties of the obtained film.

Example 2 In Example 1, except that the two layers of A / B were laminated and extruded into a film using a T-die having two inlets and two manifolds, A raw material (B) layer was about 100 μm, a raw material (A) layer was about 50 μm, and a non-oriented laminated film having a total thickness of about 150 μm was obtained.

Thereafter, using the same apparatus as used in Example 1, longitudinal stretching, transverse stretching and heat treatment were performed under the conditions described in Table 1 to produce a two-layer laminated biaxially stretched film.

The film was produced continuously for 5 hours by the above-mentioned method, but the operation could be performed smoothly without any abnormality during the production.

Table 1 shows the details of the operating conditions and the situation at the time of stretching, and Table 2 shows the measurement results of the physical properties of the obtained film.

Example 3 In Example 1, the raw materials (B) and (C) were used,
Except that the raw material (B) layer was about 50 μm each, the raw material (C) layer was about 150 μm, and the total thickness was the same as in Example 1 except that the three layers of B / C / B were extruded into a film. A non-oriented laminated film of about 200 μm was obtained.

Thereafter, using the same apparatus as used in Example 1, longitudinal stretching, transverse stretching and heat treatment were performed under the conditions shown in Table 1 to produce a three-layer laminated biaxially stretched film.

The film was produced continuously for 5 hours by the above-mentioned method, but the operation could be performed smoothly without any abnormality during the production.

 Table 1 shows the details of the operating conditions and the conditions at the time of stretching.

Examples 4 to 6 In Example 1, the longitudinal stretching, the transverse stretching and the heat treatment were performed in the first manner.
A laminated biaxially stretched film composed of three layers of B / A / B was produced in the same manner as in Example 1 except that the conditions described in the table were changed.

The film was produced continuously for 5 hours by the above-mentioned method, but the operation could be performed smoothly without any abnormality during the production.

Table 1 shows the details of the operating conditions and the conditions at the time of stretching, and Table 2 shows the measurement results of the physical properties of the film obtained in Example 5.

Comparative Examples 1 to 6 In Example 1, the longitudinal stretching, the transverse stretching and the heat treatment were performed in the first manner.
A laminated biaxially stretched film composed of three layers of B / A / B was produced in the same manner as in Example 1 except that the conditions described in the table were changed.

 Table 1 shows the details of the operating conditions and the conditions at the time of stretching.

[Effects of the Invention] According to the present invention described above, the stretching temperature, the deformation speed,
By establishing the stretching ratio and the heat treatment temperature, a biaxially stretched laminated polyamide film having a total number of layers of 5 or less can be stably produced by an industrially advantageous sequential biaxial stretching method, and the industrial value of the present invention is Is big.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-83892 (JP, A) JP-A-2-245026 (JP, A) JP-A-57-51427 (JP, A) 62129 (JP, A) JP-B 63-4217 (JP, B2) JP-B 57-8646 (JP, B2) JP-B 52-17067 (JP, B2) (58) Fields studied (Int. ⁶ , DB name) B29C 55/02-55/16 B32B 27/34

Claims (1)

(57) [Claims] Aromatic polyamides and fats containing at least 70 mol% of polyamide constituent units in the molecular chain comprising m- and / or p-xylylenediamine and α, ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms. Extruded in a molten state from two or more raw material polyamides selected from a raw material group consisting of an aromatic polyamide and a mixed polyamide thereof to obtain a non-oriented laminated film having a total number of layers of 5 or less. The film is stretched longitudinally 2.5 to 3.7 times under the conditions of 40 to 80 ° C. and an average deformation rate of 10,000% / min or more.
At a temperature of 55 to 100 ° C. and an average deformation rate of 300 to 10,000% / min., Which is 3.0 to 5.0 times transversely stretched. Then, the lower limit of the temperature of the transversely stretched film is 110 ° C. lower than the melting point of the aliphatic polyamide. A method for producing a laminated biaxially stretched film, wherein the heat treatment is performed under conditions in which the upper limit is a temperature 5 ° C. lower than the melting point of the aromatic polyamide raw material.