JP5546349B2 - Process for producing stretched semi-aromatic polyamide film and stretched semi-aromatic polyamide film produced by the method - Google Patents

Description

  The present invention relates to a method for producing a semi-aromatic polyamide stretch film and a semi-aromatic polyamide stretch film produced by the method.

  Polyamide films are used as packaging materials or industrial materials because they have excellent toughness, heat resistance, cold resistance, printing characteristics, and the like. However, the demands of the market are getting higher year by year, and a film having excellent heat resistance, heat and humidity resistance, chemical resistance, dimensional stability, etc. at higher temperatures or higher humidity is required.

  In response to such a request, Patent Document 1 discloses a polyamide mainly composed of terephthalic acid and an aliphatic alkylenediamine having 9 to 12 carbon atoms, and has a difference in intrinsic viscosity, cold crystallization temperature and glass transition temperature. A polyamide having a density in a specific range and a stretched film using the polyamide have been proposed.

  Furthermore, in Patent Document 1, as a method for producing a polyamide film, polyamide is melted and extruded into a sheet shape, which is rapidly cooled on a cooling roll cooled to a glass transition temperature (Tg) or lower and solidified by cooling. It is disclosed that the stretching temperature is (Tg + 5 ° C.) to 80 ° C.

JP 2000-186141 A (particularly claims 1, 0025, 0026)

  However, the manufacturing method disclosed in Patent Document 1 can manufacture a film at a laboratory level, but continuously and stably produce a stretched film having excellent thickness and appearance uniformity. It is difficult. On the other hand, a semi-aromatic polyamide containing an aliphatic alkylenediamine unit having 9 carbon atoms is known as a semi-aromatic polyamide, and this semi-aromatic polyamide has particularly heat resistance, low water absorption, and moisture absorption. Although it is excellent in dimensional stability and chemical resistance, when using a polyamide having a large number of 1,9-nonanediamine units among these semi-aromatic polyamides, biaxial stretching is particularly difficult. No successful examples have been reported for the industrial production of films.

  Therefore, the present invention aims to provide a method for continuously producing a semi-aromatic polyamide stretched film having excellent heat resistance, moist heat resistance, chemical resistance, dimensional stability, and excellent uniformity in appearance such as thickness. And

  When the present inventors diligently studied the production technique of the semi-aromatic polyamide stretched film, when the sheet-like molten resin is cooled and solidified using the moving cooling body surface or the like, the temperature of the moving cooling body surface or the like is within a specific range. I found out that it was necessary. In addition, the present inventors have found that a film cannot be continuously produced unless the relationship between the preheating temperature and preheating time before stretching, the stretching temperature and the strain rate of stretching is satisfied, and the present invention has been completed. It came to do.

That is, as a result of earnest research to solve the above-mentioned problems, the present inventors can continuously produce a film satisfying the above-mentioned purpose by forming and stretching a polyamide having a specific resin composition under specific conditions. As a result, the present invention has been completed.
That is, the gist of the present invention is as follows.

(A) a melt extrusion cooling step for obtaining an unstretched sheet by melt-extruding and cooling a polyamide-based resin into a sheet, and a biaxial stretching step for biaxially stretching the unstretched sheet in the longitudinal direction and the transverse direction ,
As the polyamide-based resin, a polyamide-based resin containing a dicarboxylic acid unit containing 60 to 100 mol% of a terephthalic acid unit and a diamine unit containing 60 to 100 mol% of an aliphatic alkylenediamine unit having 9 carbon atoms is used.
The cooling temperature of the moving cooling body in the melt extrusion cooling step of the polyamide-based resin is 40 ° C to 120 ° C,
The preheating temperature Tp in the biaxial stretching step is (Tg-20) to (Tg + 40) ° C. with Tg as the glass transition temperature, and Tp and the preheating time tp (seconds) satisfy the relationship of the following formula (1): A process for producing a stretched semi-aromatic polyamide film, characterized by stretching at a stretching temperature of Tg or higher and a stretching strain rate exceeding 400% / min.
1 × 10 ⁴ × EXP (−0.06 × Tp) ≦ tp ≦ 2 × 10 ⁷ × EXP (−0.1 × Tp) (1)

  (B) As a polyamide-based resin, a dicarboxylic acid unit containing 60 to 100 mol% of a terephthalic acid unit is included, and a 1,9-nonanediamine unit and, if necessary, a 2-methyl-1,8-octanediamine unit. A total of 60 to 100 mol% of diamine units and a molar ratio of 1,9-nonanediamine units to 2-methyl-1,8-octanediamine units (1,9-nonanediamine units): (2- A method for producing a stretched semi-aromatic polyamide film according to (a), wherein a polyamide-based resin having a methyl-1,8-octanediamine unit) = 50: 50 to 100: 0 is used.

  (C) A semi-aromatic polyamide stretched film produced by the method for producing a semi-aromatic polyamide stretch film according to (a) or (b) above, wherein the thickness nonuniformity is 10% or less. Group polyamide stretched film.

  (D) A stretched semi-aromatic polyamide film according to (c), wherein a film having a length of 100 m or more is wound into a roll.

  According to the present invention, a stretched semi-aromatic polyamide film having excellent heat resistance, moist heat resistance, chemical resistance, dimensional stability, and uniform thickness and appearance as compared with conventional polyamide films is continuously industrially produced. be able to. For this reason, the said film can be used conveniently for uses, such as an industrial material, an industrial material, and household goods.

It is the figure which represented the relationship of (1) Formula on the basis of the preheating temperature Tp and the preheating time tp in an Example and a comparative example.

Hereinafter, the present invention will be described in detail.
The semi-aromatic polyamide constituting the film obtained by the production method of the present invention contains a dicarboxylic acid unit containing 60 to 100 mol% of a terephthalic acid unit and 60 to 100 mol% of an aliphatic alkylenediamine unit having 9 carbon atoms. And diamine units.

  That is, the semi-aromatic polyamide contains 60 to 100 mol% of terephthalic acid units as dicarboxylic acid units as described above. Preferably it is 70-100 mol%, More preferably, it is 85-100 mol%. When the terephthalic acid unit is less than 60 mol%, the heat resistance and low water absorption of the resulting film are lowered.

  As described above, the semi-aromatic polyamide contains 60 to 100 mol% of an aliphatic alkylenediamine unit having 9 carbon atoms as a diamine unit. Preferably it is 75-100 mol%, More preferably, it is 90-100 mol%. When the content of the aliphatic alkylenediamine unit having 9 carbon atoms is less than 60 mol%, the heat resistance, low water absorption, and chemical resistance of the obtained semi-aromatic polyamide stretched film are lowered.

  Examples of the aliphatic diamine unit having 9 carbon atoms include 1,9-nonanediamine, which is a linear aliphatic alkylenediamine, 2-methyl-1,8-octanediamine, and 4-methyl-1,8-octanediamine. Can be mentioned, and one or more of these can be used.

  According to the present invention, it contains a diamine unit containing a total of 60 to 100 mol% of a 1,9-nonanediamine unit and optionally a 2-methyl-1,8-octanediamine unit, and is a 1,9-nonanediamine. The molar ratio of the unit to the 2-methyl-1,8-octanediamine unit is (1,9-nonanediamine unit) :( 2-methyl-1,8-octanediamine unit) = 50: 50 to 100: 0. It is preferable to use a polyamide-based resin. This molar ratio is more preferably (1,9-nonanediamine unit) :( 2-methyl-1,8-octanediamine unit) = 70: 30 to 100: 0, and 75:25 to 95: 5. It is particularly preferred that By using the 1,9-nonanediamine unit and the 2-methyl-1,8-octanediamine unit in the above proportions, a film having particularly excellent heat resistance and low water absorption can be obtained. Examples of such commercially available semi-aromatic polyamides include Genesta (trade name) manufactured by Kuraray.

  Polyamide raw materials other than those described above can be used in combination as long as the object of the present invention is not impaired. Examples of polyamide raw materials that can be used in combination include lactams such as ε-caprolactam, ζ-enantolactam, η-capryllactam, and ω-laurolactam; 1,4-butanediamine, 1,5-pentanediamine, 1 Linear aliphatic alkylenediamine such as 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, Branched-chain aliphatic alkylene diamines such as 4-methyl-1,8-octaneamine and 5-methyl-1,9-nonanediamine; and alicyclic diamines such as isophorone diamine, norbornane dimethylamine and tricyclodecane dimethylamine Or; aromatic diamines such as phenylenediamine; oxalic acid, malo Aliphatic dicarboxylic acids such as acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid and octadecanedioic acid; and aromatic dicarboxylic acids such as 1,4-naphthalenedicarboxylic acid and isophthalic acid Can be mentioned.

  As a guideline for selecting the polyamide raw material and the composition, it is preferable that the melting point of the semi-aromatic polyamide to be obtained is in the range of about 250 ° C to 350 ° C. When the melting point is less than 250 ° C., the heat resistance is insufficient, and when it exceeds 350 ° C., the processing temperature becomes high and the polymer undergoes thermal decomposition.

  The semi-aromatic polyamide used in the production method of the present invention preferably has an intrinsic viscosity [η] measured in concentrated sulfuric acid at 30 ° C. in the range of 0.8 to 2.0 dl / g, 0.9 More preferably, it is in the range of -1.8 dl / g. When the intrinsic viscosity [η] of the polyamide is within the above range, a stretched semi-aromatic polyamide film having excellent formability into a film and excellent mechanical properties, heat resistance and the like can be obtained.

  The semi-aromatic polyamide used in the production method of the present invention preferably has 10 mol% or more of the end groups of the molecular chain sealed with an end-capping agent. More preferably, it is 40 mol% or more, Most preferably, it is 70 mol% or more. When the end-capping rate is 10 mol% or more, the viscosity change during melt molding of the semiaromatic polyamide is small, and the resulting semiaromatic polyamide stretched film has excellent physical properties such as appearance and hot water resistance.

  The end-capping agent therefor is not particularly limited as long as it is a monofunctional compound having reactivity with the amino group or carboxyl group at the end of the polyamide, and acid anhydrides such as monocarboxylic acid, monoamine, and phthalic anhydride, Monoisocyanates, monoacid halides, monoesters, monoalcohols and the like can be used. Of these, monocarboxylic acids or monoamines are preferable from the viewpoint of reactivity and stability of the sealing end, and monocarboxylic acids are more preferable from the viewpoint of ease of handling, etc., reactivity, stability of the sealing end, and price. From these points of view, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid are preferred.

  In the stretched semi-aromatic polyamide film obtained by the production method of the present invention, a pigment such as a lubricant or titanium is used as necessary within the range not sacrificing the various properties as a film in order to further improve the various properties. , Coloring agents such as dyes, anti-coloring agents, heat stabilizers, hindered phenols, antioxidants such as phosphate esters and phosphite esters, weathering improvers such as benzotriazole compounds, bromine-based and phosphorus-based compounds A modifier, an antistatic agent, an ultraviolet absorber, an antifogging agent, various polymer resins, and the like such as a flame retardant, a plasticizer, a release agent, and a reinforcing agent such as talc can be added.

  The stretched semi-aromatic polyamide film obtained by the production method of the present invention preferably contains fine particles as an additive to improve its slipperiness. Examples of the fine particles for that purpose include inorganic particles such as silica, alumina, titanium dioxide, calcium carbonate, kaolin, and barium sulfate. Examples of the organic fine particles include acrylic resin particles, melamine resin particles, silicone resin particles, and crosslinked polystyrene particles. The average particle diameter of the fine particles can be selected in the range of 0.05 to 5.0 μm according to the friction characteristics, optical characteristics, and other required characteristics for the film.

Various methods can be used as a method of blending the above additives. The following method can be mentioned as the typical method.
(A) Method to add during polymerization of semi-aromatic polyamide (a) Master batch method to prepare pellets kneaded directly by adding to semi-aromatic polyamide (c) Direct addition to semi-aromatic polyamide during sheet film formation , Method of melt-kneading with an extruder (D) Method of directly adding to the extruder and melt-kneading when forming a sheet

  The raw material of the stretched semi-aromatic polyamide film obtained by the production method of the present invention may be a mixture of virgin raw materials, or a non-standard produced when producing a stretched semi-aromatic polyamide film. It may be a film, a scrap mixture generated as an ear trim, or a virgin raw material added to the scrap mixture. The mixing can be performed by a known method such as a dry blending method using a known apparatus, a kneading method in which a uniaxial or biaxial extruder is used for melt kneading and mixing.

  The stretched semi-aromatic polyamide film may be subjected to corona treatment, plasma treatment, acid treatment, flame treatment, coating treatment, etc. in order to improve the adhesion of the film surface.

  Various coating agents can be applied to the surface of the semi-aromatic polyamide film in order to impart functions such as easy adhesion, antistatic properties, releasability, and gas barrier properties. The coating can be applied to the film after stretching, or can be applied to the film before stretching, or it can be coated immediately before the stretching machine, and dried and formed into a film in the preheating section of the stretching machine. .

  Next, the detail of the manufacturing method of the semi-aromatic polyamide stretched film of this invention is demonstrated. According to the method of the present invention, a film having a length of 100 m or more can be continuously produced. Although the stretched semi-aromatic polyamide film can be made into a single sheet, it is preferably in the form of a film roll from the viewpoint of productivity when used in various applications.

  According to the production method of the present invention, the above-mentioned semi-aromatic polyamide and the additive blended therein are melt-extruded by an extruder, and a polymer melt is discharged in a sheet form from a flat die such as a T die or I die, An unstretched sheet is obtained by contacting and cooling a cooling surface of a moving cooling body such as a cooling roll or a steel belt. At this time, the extrusion temperature is preferably not lower than the melting point (Tm) of the semi-aromatic polyamide and not higher than 370 ° C. If the extrusion temperature is lower than the melting point, the viscosity may increase and the extrusion may not be possible, and if it exceeds 370 ° C., the semi-aromatic polyamide may be decomposed.

  The temperature of the moving cooling body is required to be 40 ° C to 120 ° C, more preferably 45 ° C to 90 ° C, and further preferably 45 ° C to 60 ° C. Normally, polyamide has a high crystallization rate, and when it is slowly cooled, crystals grow and it becomes difficult to stretch. Therefore, in order to achieve both improvement in cooling efficiency and suppression of condensation of water droplets on the moving cooling body, It is usual to cool down in the vicinity.

  When the temperature of the moving cooling body exceeds 120 ° C., it takes a long time until the molten polymer develops an appropriate hardness on the moving cooling body, and it becomes difficult to come off the moving cooling body. As a result, for example, when the moving cooling body is a roll, it breaks and winds around the roll, or even if it does not break, the pulsation occurs due to the momentum when the film comes off the roll. In addition, crystals with different sizes are generated in the unstretched sheet, and stretching unevenness occurs or stretching becomes difficult.

  Moreover, when the semi-aromatic polyamide used in the production method of the present invention is rapidly cooled with a moving cooling body of less than 40 ° C., the portion that has not yet contacted the moving cooling body (cooling roll) in the molten polymer becomes hard, The hardened part does not adhere to the moving cooling body (cooling roll). As a result, the unstretched film has a portion that is in close contact with the moving cooling body and a portion that is not in close contact with each other, and cannot be stably operated. Further, in the subsequent stretching step, breakage or non-uniform stretching occurs. In addition to the resin characteristics of high crystallization speed, the glass transition temperature (Tg) is high, and the resin characteristic of high elastic modulus and high hardness in the low temperature region prevents uniform adhesion with the moving cooling body, resulting in local This is considered to be caused by the occurrence of uneven cooling rate.

  In order to obtain a sheet by uniformly cooling and solidifying the polymer melt, a method such as an air knife casting method, an electrostatic application method, a vacuum chamber method, or the like is used as a method for bringing the polymer melt into close contact with the moving cooling body and cooling and solidifying. Can be used.

  The obtained unstretched sheet usually has a thickness of about 10 μm to 3 mm, and has excellent properties such as low water absorption and chemical resistance, but has a thickness of about 0.5 μm to 1.5 mm. By biaxially stretching, low water absorption, chemical resistance, heat resistance, and mechanical strength are further improved.

  As a stretching method therefor, a flat sequential biaxial stretching method, a flat simultaneous biaxial stretching method, a tubular method, or the like can be used. Among them, the flat simultaneous biaxial stretching method is optimal because the film thickness accuracy is good and the physical properties in the film width direction are uniform. As a stretching apparatus for the flat simultaneous biaxial stretching method, a screw type tenter, a pantograph type tenter, a linear motor driven clip type tenter, or the like can be used. The draw ratio is 1.5 to 10 times in the machine direction (MD direction) and the transverse direction (TD direction), respectively, because the heat resistance and mechanical strength of the finally obtained semi-aromatic polyamide film are excellent. It is preferable that it is 2 times to 5 times.

  The stretching speed requires that the stretching strain rate in the MD direction and the TD direction both exceed 400% / min, and is preferably 800% / min or more and 12000% / min or less, and is preferably 1200% / min. More preferably, it is at least 6000% / min. When the strain rate is 400% / min or less, crystals grow during stretching and the film breaks. On the other hand, if the strain rate is too high, the unstretched sheet may not follow the deformation and may break.

An unstretched film needs to be preheated before stretching. In order to obtain the stretched semi-aromatic polyamide film of the present invention, the preheating temperature Tp and the preheating time tp satisfy the relationship of the following formula (1), and Tp is (Tg-20) to (Tg + 40) ° C. It is necessary. Tp is preferably (Tg−15) to (Tg + 35) ° C. Further, tp is in a practical range of 1 to 60 seconds.
1 × 10 ⁴ × EXP (−0.06 × Tp) ≦ tp ≦ 2 × 10 ⁷ × EXP (−0.1 × Tp) (1)

  When the preheating temperature Tp is less than (Tg−20) ° C., the film is easily broken during stretching, the load applied to the stretching machine is large, and troubles on equipment are likely to occur. Further, when the preheating temperature exceeds (Tg + 40) ° C., stretching unevenness and film breakage are likely to occur.

  When the left side of the formula (1) is not satisfied, the film is not sufficiently preheated, and the film is stretched while being hard. For this reason, the film may be cut or the stretching stress becomes too high, resulting in a high load on the apparatus and a failure.

  When the right side of the equation (1) is not satisfied, the film is preheated excessively and crystallization proceeds before stretching. For this reason, when it is originally desired to crystallize by orientation, the crystallization partially progresses before stretching, which tends to cause unevenness and cause breakage.

  The stretching temperature needs to be a temperature equal to or higher than Tg, and more preferably exceeds Tg and equal to or lower than (Tg + 50) ° C. When the stretching temperature is less than Tg, the film is easily broken and stable production cannot be performed. On the other hand, if it exceeds (Tg + 50) ° C., stretching unevenness may occur.

  After performing the stretching as described above, it is preferable to perform a heat setting treatment as necessary while holding the film with a clip for stretching. A preferable heat setting treatment temperature is 200 ° C to (Tm-5) ° C, and more preferably 240 ° C to (Tm-10) ° C. Further, after the heat setting treatment, it is preferable to perform 1 to 10% relaxation treatment as needed while holding the film, and more preferably 3 to 7% relaxation treatment. By performing the relaxation treatment, sufficient dimensional stability can be obtained.

  A semi-aromatic polyamide stretched film roll is obtained by performing heat setting treatment and relaxation treatment as desired, and then cooling and winding up on a take-up roll. The obtained semi-aromatic polyamide stretched film roll can be slit again to a desired width to make a semi-aromatic polyamide stretched film roll again.

  The thickness of the stretched semi-aromatic polyamide film is not particularly limited. For example, as a polyamide-type resin film for packaging, 8-50 micrometers is preferable and 10-30 micrometers is more preferable. However, in the stretched semi-aromatic polyamide film of the present invention, it is necessary that the thickness unevenness R obtained as described below is 10% or less. Preferably it is 8% or less, More preferably, it is 6% or less. If the thickness unevenness R exceeds 10%, it causes slack and wrinkles of the film during processing, causes of coating defects and lamination defects, and causes quality defects of the final product.

  The thus obtained semi-aromatic polyamide stretched film of the present invention is provided with a coating layer or vapor deposition layer on the surface, laminated with other polymers, etc., if necessary, paper, metal foil, It can be used by laminating or printing with woven fabric, non-woven fabric, wood or the like.

  Examples of paints that form the coating layer include gas barrier paints (polyvinyl alcohol aqueous solution, polyvinylidene chloride, etc.), easy-adhesion paints (urethane-based, ester-based, olefin-based dispersions), antistatic paints (interfaces) Activator, conductive polymer, carbon, metal oxide, etc.), UV absorbing paint (HALS, zinc oxide, etc.), hard coat paint (acrylic, silane coupling agent, etc.), Examples include release coatings (silicone, olefin, etc.).

  Examples of the vapor deposition layer include inorganic layers such as alumina and silica, and organic layers such as melamine.

  Examples of polymers to be laminated include high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, ultrahigh molecular weight polyethylene, polypropylene, ethylene / propylene copolymer (EPR), and ethylene / butene copolymer. (EBR), ethylene / vinyl acetate copolymer (EVA), ethylene / vinyl acetate copolymer saponified product (EVOH), ethylene / acrylic acid copolymer (EAA), ethylene / methacrylic acid copolymer (EMAA), Polyolefin resins such as ethylene / methyl acrylate copolymer (EMA), ethylene / methyl methacrylate copolymer (EMMA), ethylene / ethyl acrylate copolymer (EEA); acrylic acid, methacrylic acid, maleic acid, Fumaric acid, itaconic acid, crotonic acid, mesaconic acid, citraconic acid Carboxyl group-containing unsaturated compounds such as glutaconic acid, cis-4-cyclohexene-1,2-dicarboxylic acid, endobicyclo- [2.2.1] -5-heptene-2,3-dicarboxylic acid, and metal salts thereof ( Na, Zn, K, Ca, Mg); acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, endobicyclo- [2.2.1] -5-heptene-2,3 dicarboxylic acid anhydride Group-containing unsaturated compounds; glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, glycidyl citraconic acid, etc., such as carboxyl group or its metal salt, acid anhydride group, epoxy Polyolefin resins having functional groups such as groups introduced therein; polybutylene terephthalate, polyethylene Polyester resins such as phthalate, polyethylene isophthalate, PET / PEI copolymer, polyarylate, polybutylene naphthalate, polyethylene naphthalate, and liquid crystal polyester; polyether resins such as polyacetal and polyphenylene oxide; polysulfone, polyethersulfone, etc. Polysulfone resins such as polyphenylene sulfide and polythioether sulfone; polyketone resins such as polyether ether ketone and polyallyl ether ketone; polyacrylonitrile, polymethacrylonitrile, acrylonitrile / styrene copolymer, methacrylate Ronitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer (ABS), methacrylonitrile / styrene / butadiene copolymer Polynitrile resins such as coalescence (MBS); Polymethacrylate resins such as polymethyl methacrylate and polyethyl methacrylate; Polyvinyl ester resins such as polyvinyl acetate; Polyvinylidene chloride, polyvinyl chloride, polyvinyl chloride / vinylidene chloride Polyvinyl chloride resins such as polymers and vinylidene chloride / methyl acrylate copolymers; Cellulosic resins such as cellulose acetate and cellulose butyrate; Polycarbonate resins such as polycarbonate; Polyimides such as thermoplastic polyimide, polyamideimide and polyetherimide Resins: polyvinylidene fluoride, polyvinyl fluoride, ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene / chlorotrifluoroethylene copolymer (ECTF) ), Tetrafluoroethylene / hexafluoropropylene copolymer (TFE / HFP, FEP), tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer (TFE / HFP / VDF, THV), tetrafluoroethylene / fluoro ( Fluorine resins such as alkyl vinyl ether) copolymers (PFA); thermoplastic polyurethane resins; polyurethane elastomers, polyester elastomers, polyamide elastomers, and the like.

Hereinafter, the present invention will be described specifically by way of examples.
The evaluation methods of various physical properties in the following examples and comparative examples were as follows. Unless otherwise specified, all measurements were performed in an environment of a temperature of 20 ° C. and a humidity of 65%.

<Evaluation method>
1. Intrinsic viscosity of semi-aromatic polyamide [η]
The intrinsic viscosity (ηinh) of each sample of 0.05, 0.1, 0.2, and 0.4 g / dl in concentrated sulfuric acid at 30 ° C. was obtained from the following formula, and this was excluded from the concentration 0 The inserted value was defined as intrinsic viscosity [η].
ηinh = [ln (t1 / t0)] / c
[Where ηinh is the intrinsic viscosity (dl / g), t0 is the solvent flow time (seconds), t1 is the sample solution flow time (seconds), and c is the concentration of the sample in the solution (g / dl) . ]

2. Melting point (Tm) and glass transition temperature (Tg) of semi-aromatic polyamide
Using a DSC apparatus (DSC7 manufactured by PerkinElmer Co., Ltd.), the semi-aromatic polyamides of Reference Examples 1 to 3 described later were heated from 20 ° C. to 350 ° C. at + 10 ° C./min and held for 5 minutes in a nitrogen atmosphere. After (1st Scan), it was cooled from 350 ° C. to 20 ° C. at 100 ° C./min and held for 5 minutes. Furthermore, the glass transition temperature in the process (2nd Scan) in which the temperature was raised again from 20 ° C. to 350 ° C. at + 10 ° C./min was defined as Tg of the semiaromatic polyamide. Similarly, the peak top temperature of the crystal melting peak observed with 2nd Scan was defined as Tm.

3. Unevenness of stretched semiaromatic polyamide film The thickness of the film was measured using a thickness meter “MT12B” manufactured by HEIDENHAIN. Thickness unevenness R is the maximum value of 30 measurement values obtained by measuring the thickness of the center and both ends of the entire width direction of the film 10 times per 1 m in the longitudinal direction at an arbitrary position of the roll-shaped film. Is Lmax, the minimum value is Lmin, and the average value is La,
R = (Lmax−Lmin) / 2La × 100
Expressed in In addition, both ends means the position of the distance of 10% of full width toward the center from the both ends of the film along the width direction.

4). Stretch strain rate Calculation was carried out using the following formula.
α: Stretch ratio. For longitudinal stretching, α = V ₀ / V _I
For transverse stretching, α = W ₀ / W _I
V _I : Preheating supply section speed [m / min]
V ₀ : Stretch outlet speed [m / min]
V: Average stretching speed [m / min] = (V _I + V ₀ ) / 2
W _I : film width [m] at the inlet of the preheating supply section
W ₀ : width of the film at the exit of the stretching machine [m]
L: Stretched part distance [m]
Stretch strain rate = (α-1) × 100 × V / L

Reference Example 1 (Production of semi-aromatic polyamide)
3289 parts by mass of terephthalic acid (TA), 2533 parts by mass of 1,9-nonanediamine (NMDA), 633 parts by mass of 2-methyl-1,8-octanediamine (MODA), 48.9 parts by mass of benzoic acid (BA), 6.5 parts by mass of sodium phosphite monohydrate (0.1% by mass based on the total of the above four polyamide raw materials) and 2200 parts by mass of distilled water were placed in a reaction kettle and purged with nitrogen. These ratios were TA / BA / NMDA / MODA = 99/2/80/20 (molar ratio). And after stirring for 30 minutes at 100 degreeC, internal temperature was heated up to 210 degreeC over 2 hours. At this time, the pressure in the reaction kettle was increased to 2.12 MPa (22 kg / cm ² ). The reaction was continued for 1 hour, and then the temperature was raised to 230 ° C., and then the temperature was maintained at 230 ° C. for 2 hours. The reaction was carried out while gradually removing water vapor and keeping the pressure at 2.12 MPa (22 kg / cm ² ). . Next, the pressure was reduced to 0.98 MPa (10 kg / cm ² ) over 30 minutes, and the reaction was further continued for 1 hour to obtain a prepolymer having an intrinsic viscosity of 0.30 dl / g. This was dried at 100 ° C. under reduced pressure for 12 hours, and then pulverized to a size of 2 mm or less. Next, this was subjected to solid phase polymerization for 10 hours under the conditions of a temperature of 230 ° C. and a pressure of 13.3 Pa (0.1 mmHg) to obtain a white semi-aromatic polyamide having a melting point of 290 ° C. and an intrinsic viscosity of 1.25 dl / g. . This was supplied to a twin screw extruder (“TEX44C” manufactured by Nippon Steel Co., Ltd.), melt kneaded and extruded under the condition of a cylinder temperature of 320 ° C., cooled and cut to produce a pellet-like semi-aromatic polyamide. .

Table 1 shows the melting point, glass transition temperature, and intrinsic viscosity of the produced semi-aromatic polyamide.
Reference Example 2 and Reference Example 3 (Production of semi-aromatic polyamide)
A semi-aromatic polyamide was produced in the same manner as in Reference Example 1 using terephthalic acid, 1,9-nonanediamine, and 2-methyl-1,8-octanediamine in the proportions shown in Table 1, respectively.

  Table 1 shows the melting point, glass transition temperature, and intrinsic viscosity of the semi-aromatic polyamides of Reference Examples 2 and 3.

Example 1
The semi-aromatic polyamide of Reference Example 1 (R1) was charged into a 65 mm single-screw extruder having cylinder temperatures of 295 ° C. (front stage), 320 ° C. (middle stage) and 320 ° C. (second stage), and melted to 320 ° C. Extruded into a sheet form from the T-die, and cooled by pressing and adhering to a cooling roll with a circulating oil temperature set to 50 ° C. by an electrostatic application method to form a substantially unoriented unstretched film having a thickness of 240 μm Obtained.

The cooling roll used was coated with ceramic _(Al 2 _{O 3)} to 0.15mm thickness on the surface. Further, two carbon brushes were arranged on the upstream side of the point where the roll surface and the film were in contact with each other and brought into contact with the cooling roll, and the surface of the ceramic coating layer was discharged by grounding the carbon brush holder. A tungsten wire having a diameter of 0.2 mm was used as an electrode, and a voltage of 6.5 kV was applied with a 300 W (15 kV × 20 mA) DC high voltage generator.

  Next, while holding both ends of this unstretched film with clips, it is led to a tenter type simultaneous biaxial stretching machine (manufactured by Hitachi, Ltd.) having an inlet width of 193 mm and an outlet width of 605 mm, and a preheating part temperature of 120 ° C. Simultaneous biaxial stretching was performed at 130 ° C., a longitudinal stretching strain rate of 2400% / min, a transverse stretching strain rate of 2760% / min, a longitudinal stretching ratio of 3.0 times, and a transverse stretching ratio of 3.3 times. And after heat fixing at 250 ° C. in the same tenter, after 5% relaxation treatment in the width direction of the film, it is uniformly cooled, the film ends are released from the clips, the ears are trimmed, A length of 500 m was wound up with a width of 0.5 m, and a biaxially stretched semi-aromatic polyamide stretched film having a thickness of 25 μm was obtained. The film winding speed was 18 m / min. The obtained semi-aromatic polyamide stretched film had no severing, stable operability, excellent thickness uniformity of 10% or less, transparency of haze of 1.5%, and good appearance.

  The evaluation results of the semi-aromatic polyamide stretched film of Example 1 are shown in Tables 2 and 3.

Examples 2-8
Compared to Example 1, the film production conditions such as the cooling roll temperature, stretching strain rate, preheating temperature, stretching temperature, and heat setting temperature were changed as shown in Table 3. Other than that was carried out similarly to Example 1, and manufactured the film. Table 3 shows the production conditions of each film and the characteristics of the obtained semi-aromatic polyamide stretched film.

  Since Examples 1 to 8 were all according to the production method of the present invention, the film could be stretched satisfactorily using a semi-aromatic polyamide, and the obtained stretched film had little thickness unevenness. Met.

Comparative Examples 1-6
Compared to Example 1, the manufacturing conditions were changed as shown in Table 3. Other than that, an attempt was made to produce a film in the same manner as in Example 1.

As such, since Comparative Example 1 did not satisfy the condition on the left side of the formula (1), the film was broken in the stretching section of the preheating time stretching machine, and a stretched film could not be obtained. Since the comparative example 2 did not satisfy the conditions on the right side of the formula (1) and the stretching strain rate was too low, the film was broken at the initial stage of the stretching section of the stretching machine, and a stretched film could not be obtained. Since the comparative example 3 did not satisfy the condition of the left side of the formula (1) like the comparative example 1, it broke at the initial stage of the stretching section of the stretching machine, and a stretched film could not be obtained. In Comparative Example 4, a stretched film could be obtained, but as in Comparative Example 2, the right side condition of the formula (1) was not satisfied, and the stretching strain rate was too low, so the stretching unevenness was large. Since the comparative example 5 did not satisfy the condition of the left side of the formula (1) like the comparative example 1, it broke at the initial stage of the stretching section of the stretching machine, and a stretched film could not be obtained. Since the comparative example 6 did not satisfy the conditions on the right side of the expression (1) as in the comparative example 2, it was broken at the initial stage of the stretching section of the stretching machine, and a stretched film could not be obtained.
The results of Comparative Examples 1-6 are shown in Table 3.

  FIG. 1 is a graph in which data of Examples 1 to 8 and Comparative Examples 1 to 6 are plotted with the preheating temperature Tp on the horizontal axis and the preheating time tp on the vertical axis. In the figure, the solid line indicates the value of the left side of the expression (1) (“Expression A” in Table 2), and the broken line indicates the value of the right side of the expression (1) (“Expression B” in Table 2). That is, in FIG. 1, when the preheating temperature Tp and the preheating time tp change, processing is performed with the preheating temperature Tp and the preheating time tp in the region between the solid line of “Formula A” and the broken line of “Formula B”. This means that the desired result can be obtained by satisfying the conditions of the present invention, and if this region is treated with a preheating temperature Tp or a preheating time tp outside the range, the conditions of the present invention are not satisfied. It means that the result of the period cannot be obtained.

Examples 9-16, Comparative Examples 7-12
Compared with Examples 1-8 and Comparative Examples 1-6, the resin used was changed to the resin of Reference Example 2 (R2). Other than that was made the same as Examples 1-8 and Comparative Examples 1-6.

  The results are shown in Table 4. Although these Examples 9-16 and Comparative Examples 7-12 differed in resin used compared with Examples 1-8 and Comparative Examples 1-6 as mentioned above, Examples 1-8, The same results as in Comparative Examples 1 to 6 were shown.

Examples 17-24, Comparative Examples 13-18
Compared with Examples 1-8 and Comparative Examples 1-6, the resin used was changed to the resin of Reference Example 3 (R3). Other than that was made the same as Examples 1-8 and Comparative Examples 1-6.

  The results are shown in Table 5. Although these Examples 17-24 and Comparative Examples 13-18 differed in resin used compared with Examples 1-8 and Comparative Examples 1-6 as mentioned above, Examples 1-8, The same results as in Comparative Examples 1 to 6 were shown.

Example 25
Under the same conditions as in Example 1, the film was wound up by continuously stretching 10000 m in length. As a result, the operability and the appearance were good, and a semi-aromatic polyamide stretched film roll could be obtained without problems. The film thickness unevenness R was 4.7%.

Example 26
Compared with Example 1, the method of pressing the sheet-like melt extruded from the T-die to the cooling roll was changed to the air knife method, and a cooling roll having a hard chrome plating surface coating was used. Otherwise, under the same conditions as in Example 1, the film was wound up by continuously stretching 10000 m in length. The air knife device was used at a lip interval of 1 mm and an air pressure of 4 kPa. As a result, the operability and the appearance were good, and a semi-aromatic polyamide stretched film roll could be obtained without problems. This film had a thickness unevenness R of 4.2%.

Examples 27-30
Compared to Example 1, the film production conditions such as the cooling roll temperature, stretching strain rate, preheating temperature, stretching temperature, and heat setting temperature were changed as shown in Table 6. Other than that was carried out similarly to Example 1, and manufactured the film. Table 6 shows the production conditions of each film and the characteristics of the obtained semi-aromatic polyamide stretched film.

Comparative Example 19
Compared with Example 1, the cooling roll which set the temperature of circulating oil to 35 degreeC was used. Other than that was carried out similarly to Example 1, and produced the unstretched film. However, the portion of the molten polymer not yet in contact with the cooling roll became hard and the portion did not adhere to the cooling roll. Therefore, in the unstretched film, the part which closely_contact | adheres to the cooling roll which is a moving cooling body, and the part which does not contact | adhere appear, and it was not able to operate stably. As a result, it was not possible to proceed to the stretching process.

Comparative Example 20
Compared with Example 1, the cooling roll which set the temperature of circulating oil to 125 degreeC was used. Other than that was carried out similarly to Example 1, and produced the unstretched film. However, pulsation occurred when the unstretched film peeled from the cooling roll, and stable operation was not possible. For this reason, it was not possible to proceed to the stretching process.

Comparative Example 21
Compared to Example 3, the preheating temperature in the biaxial stretching process was changed to 95 ° C. Otherwise, the production of a film was attempted in the same manner as in Example 3. However, the film was frequently broken during stretching and could not be operated stably.

Comparative Example 22
Compared to Example 1, the preheating temperature in the biaxial stretching process was changed to 170 ° C. Otherwise, the production of a film was attempted in the same manner as in Example 1. However, the film was frequently broken during stretching and could not be operated stably.

  The polyamide film of the present invention is excellent in mechanical properties, flexibility and adhesiveness, and is excellent in heat resistance, moist heat resistance, chemical resistance and low water absorption as compared with conventional polyamide films. For this reason, pharmaceutical packaging materials; food packaging materials such as retort foods; electronic parts packaging materials for semiconductor packages, etc .; electrical insulation materials for motors, transformers, cables, etc .; dielectric materials for capacitor applications, etc .; cassette tapes, digital Magnetic tape materials such as magnetic tape for data storage and data tape for data storage; protective plates for solar cell substrates, liquid crystal plates, conductive films, display devices; LED mounting substrates, flexible printed wiring boards, flexible flat cables, etc. Electronic substrate materials; heat-resistant adhesive tapes such as FPC coverlay films, heat-resistant masking tapes, industrial process tapes; heat-resistant barcode labels; heat-resistant reflectors; various release films; heat-resistant adhesive base films; Agricultural materials; medical materials; civil engineering, building materials ; Filtration membrane or the like; domestic, as such a film for industrial materials can be suitably used.

Claims (4)

A melt extrusion cooling step of obtaining an unstretched sheet by melt-extruding and cooling a polyamide-based resin into a sheet, and a biaxial stretching step of biaxially stretching the unstretched sheet in the longitudinal direction and the transverse direction,
As the polyamide-based resin, a polyamide-based resin containing a dicarboxylic acid unit containing 60 to 100 mol% of a terephthalic acid unit and a diamine unit containing 60 to 100 mol% of an aliphatic alkylenediamine unit having 9 carbon atoms is used.
The cooling temperature of the moving cooling body in the melt extrusion cooling step of the polyamide-based resin is 40 ° C to 120 ° C,
The preheating temperature Tp in the biaxial stretching step is (Tg-20) to (Tg + 40) ° C. with Tg as the glass transition temperature, and Tp and the preheating time tp (seconds) satisfy the relationship of the following formula (1): A process for producing a stretched semi-aromatic polyamide film, characterized by stretching at a stretching temperature of Tg or higher and a stretching strain rate exceeding 400% / min.
1 × 10 ⁴ × EXP (−0.06 × Tp) ≦ tp ≦ 2 × 10 ⁷ × EXP (−0.1 × Tp) (1)   The polyamide-based resin includes a dicarboxylic acid unit containing 60 to 100 mol% of terephthalic acid units, and a total of 60 of 1,9-nonanediamine units and optionally 2-methyl-1,8-octanediamine units. The diamine unit is contained in an amount of ˜100 mol%, and the molar ratio of the 1,9-nonanediamine unit to the 2-methyl-1,8-octanediamine unit is (1,9-nonanediamine unit): (2-methyl-1 , 8-octanediamine unit) = 50: 50 to 100: 0, a polyamide-based resin is used. The method for producing a stretched semi-aromatic polyamide film according to claim 1.   A semi-aromatic polyamide stretched film produced by the method for producing a semi-aromatic polyamide stretch film according to claim 1 or 2, wherein the uneven thickness is 10% or less. .   The stretched semi-aromatic polyamide film according to claim 3, wherein a film having a length of 100 m or more is wound in a roll shape.

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