JP2009515020A - Method for extruding thin films from aromatic polyamide-imide compositions - Google Patents

Abstract

  A method for extruding a film (F) having a thickness of 1000 μm or less from a polymer composition (C), wherein the polymer composition (C) is at least 40 based on the total mass of the polymer composition (C). % By weight of at least one aromatic polyamide-imide, the aromatic polyamide-imide comprising: trimellitic anhydride monobasic acid halide; at least one comonomer selected from diamines and diisocyanates, and anhydride groups and A process comprising a polycondensation reaction of at least one substance (S) comprising only one functional group capable of reacting with either an acid halide group or on the other hand with either an amine group or an isocyanate group, or only a precursor of said functional group Wherein the amount of substance (S) is 1 mol% or more based on the total number of moles of trimellitic monobasic acid halide and substance (S).

Description

Detailed Description of the Invention

  This application claims the benefit of US Application No. 60/734752, filed Nov. 9, 2005, the entire contents of which are hereby incorporated by reference.

〔Technical field〕
The present invention relates to a method for extruding a thin film from an aromatic polyamide-imide composition.

[Background Technology]
High temperature thin films, and particularly high temperature very thin films, are currently popular with polyimides such as KAPTON® grade. They are manufactured by solution casting and require the use of organic solvents. It is well known that those skilled in the art do not like the use of organic solvents.
A solvent-free variant was proposed by Emery et al. (US Pat. No. 4,581,264), which consisted of extruded polyamide-imide films. It works to some extent, but in some other cases, especially very thin films, polymer compositions with very high polyamide-imide content, ie as detailed in US Pat. No. 4,581,264. It has proved unsuccessful when it has to be manufactured from what actually provides the most attractive properties.

  U.S. Pat.No. 4,581,264 discloses aromatic polyamides through melt channels and extrusion dies at continuously increasing shear rates and temperatures of about 302 ° C. to about 360 ° C. (about 575 ° F. to about 680 ° F.). A process for extruding various articles from an imide composition is described. Among them are thin or thick sheets, thick tubes and thin films. The thin films of U.S. Pat. No. 4,581,264 are reported to have thicknesses that vary from 1 mil to 15 mils in some cases. Example 1 describes the production of a film having a thickness of 6.5 mils by extruding a smooth polyamide-imide polymer. In contrast, the film of Example 2 having a thin thickness (ie, 3 mils) was extruded from an 80:20 mixture of polyamide-imide polymer and ULTEM® polyetherimide rather than a smooth polyamide-imide polymer. It was done. ULTEM® polyetherimides usually exhibit significantly lower levels of properties than polyamide-imides, but act as processing aids. Thus, although the use of ULTEM® polyetherimide in Example 2 is detrimental to properties, it is actually 0.076 mils (0.003 inches) based on the extrusion method taught in US Pat. No. 4,581,284. It was necessary to successfully extrude a thin film.

In fact, the extrusion process described in U.S. Pat. No. 4,581,264 is very thin from a smooth polyamide-imide polymer and a polymer composition comprising more than 80% by weight polyamide-imide more generally. It does not adapt well to extrude films (typically 4 mils or less).
Improved method for extruding films from polyamide-imide compositions, particularly well suited for extruding very thin films of good appearance from polymer compositions containing polyamide-imide well above 80% by weight A method is highly desired.
This need and yet other needs are met by the present invention.

[Disclosure of the Invention]
A certain feature of the present invention is a method for extruding a film (F) having a thickness of 1000 μm or less from a polymer composition (C), wherein the polymer composition (C) is the polymer composition (C). Comprising at least 40% by weight of at least one aromatic polyamide-imide, based on the total weight of the aromatic polyamide-imide:
Trimellitic anhydride monobasic acid halide;
At least one comonomer selected from diamines and diisocyanates, and the only functional group capable of reacting with either an anhydride group and an acid halide group on the one hand or an amine group and an isocyanate group on the other hand, or the only said functional group At least one substance (S) comprising a precursor of
Produced by a process comprising a polycondensation reaction of
The amount of substance (S) relates to a process wherein the amount of the trimellito monobasic acid halide and the substance (S) is 1 mol% or more based on the total number of moles.

Such a method results in a polyamide-imide film with improved quality, especially a good-looking polyamide-imide film as thin as 25 μm with a very high polyamide-imide content (typically 85% by weight or more) Without the use of solvents.
Another feature of the present invention relates to a film obtained by the above method.
A feature of the invention of particular interest is a method for extruding a film (F) having a thickness of 1000 μm or less from a polymer composition (C), wherein the polymer composition (C) is the polymer composition ( C) comprising at least 40% by weight of at least one aromatic polyamide-imide, based on the total weight of C, wherein the aromatic polyamide-imide is a combination of (i) trimellitic anhydride monobasic acid halide and trimellitic acid monomer And (ii) produced by a process comprising a polycondensation reaction between at least one comonomer selected from diamines and diisocyanates, the amount of trimellitic acid being 2 mol% or more based on the total number of moles of acid monomers Regarding the method.

Detailed Description of the Invention
Film (F)
The thickness (t) of the film (F) is advantageously defined as:
t = ∫vτ (x, y, z) dx dy dz / V
Where x, y and z are coordinates in a three-dimensional space of a unit volume dV (dV is equal to dx × dy × dz) of a film (F) with a total simple volume V, and τ is a local thickness. is there.

The local thickness associated with the mass point coordinates (x, y, z) is defined as the length of the shortest straight line D containing the mass point of interest and spans the film (F) (i.e., D is the film ( From the mass point entering F), D extends the film (F) to the Dell mass point).
The thickness of the film (F) is preferably 100 μm or less, more preferably less than 75 μm, more preferably less than 55 μm, more preferably less than 40 μm and most preferably less than 30 μm. Furthermore, the thickness of the film (F) is advantageously greater than 10 μm, preferably greater than 15 μm and more preferably greater than 20 μm.

Polymer composition (C)
Aromatic polyamide-imide In the present invention, “aromatic polyamide-imide” comprises at least one aromatic ring, at least one imide group as it is and / or in the form of an amide acid, and the amide acid form of the imide group Is intended to mean any polymer comprising more than 50% by weight of repeating units [repeat units (R1)] containing at least one amide group.
Preferably, the aromatic polyamide-imide contains more than 90% by weight of repeating units (R1). More preferably, it contains no repeating unit other than the repeating unit (R1).

式中:
Arは典型的には以下であり:

Rは典型的には以下である:

The repeating unit (R1) is advantageously:

Where:
Ar is typically:

R is typically:

及び/又は以下の繰り返し単位を含有する対応アミド-アミド酸:

式中、(i-b)に示されているような2つのアミド基の芳香環への連結は、1,3及び1,4ポリアミドアミド酸配置を表していると理解される;

及び/又は以下の繰り返し単位を含有する対応アミド-アミド酸:

式中、(ii-b)に示されているような2つのアミド基の芳香環への連結は、1,3及び1,4ポリアミドアミド酸配置を表していると理解される;及び

及び/又は以下の繰り返し単位を含有する対応アミド-アミド酸:

式中、(iii-b)に示されているような2つのアミド基の芳香環への連結は、1,3及び1,4ポリアミドアミド酸配置を表していると理解される。 The repeating unit (R1) is preferably selected from:

And / or the corresponding amide-amide acid containing the following repeating units:

Where the linkage of two amide groups to the aromatic ring as shown in (ib) is understood to represent 1,3 and 1,4 polyamidoamidic acid configurations;

And / or the corresponding amide-amide acid containing the following repeating units:

Wherein the linkage of two amide groups to the aromatic ring as shown in (ii-b) is understood to represent 1,3 and 1,4 polyamidoamidic acid configurations; and

And / or the corresponding amide-amide acid containing the following repeating units:

Where the linkage of two amide groups to the aromatic ring as shown in (iii-b) is understood to represent 1,3 and 1,4 polyamidoamidic acid configurations.

The repeating unit (R1) is very preferably a mixture of repeating units (ii) and (iii).
Excellent results have been obtained with aromatic polyamide-imides consisting of a mixture of repeating units (ii) and (iii).
A polymer commercially available from Solvay Advanced Polymers as TORLON® polyamide-imide follows this standard.

The aromatic polyamide-imide used in the method of the present invention is:
Trimellitic anhydride monobasic acid halide;
At least one comonomer selected from diamines and diisocyanates, and the only functional group capable of reacting with either an anhydride group and an acid halide group on the one hand, or an amine group and an isocyanate group on the other hand, or the only said function At least one substance (S) comprising a precursor of the group,
Produced by a process comprising a polycondensation reaction of
The amount of substance (S) is 1 mol% or more based on the total number of moles of trimellitic monobasic acid halide and substance (S).

As trimellitic anhydride monobasic acid halide, 4-trimellitic anhydride chloride is preferred.
The comonomer preferably comprises at least one aromatic ring. More preferably, it contains at most two kinds of aromatic rings.
The comonomer is preferably a diamine. As examples of diamines, mention may be made of: paraphenylenediamine, benzidine, 4-[(4-aminophenyl) methyl] aniline. More preferably, the diamine is selected from the group consisting of 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, mphenylenediamine and mixtures thereof.

The substance (S) contains either an anhydride group and an acid halide group on the one hand, or an amine group and an isocyanate group on the other hand, or the only functional group that can react with the precursor of said functional group.
Substances (S) containing only functional groups that can react with anhydride groups and acid halide groups may include aniline, naphthylamine, anisidine and phenyl isocyanate.
Substances (S) containing only functional groups capable of reacting with amine groups and isocyanate groups (S) include phthalic anhydride, 1,8-naphthalene anhydride, 1,2-cyclohexene dicarboxylic anhydride (cis or trans), anhydride Mention may be made of succinic acid, maleic anhydride, benzoic anhydride, benzoyl chloride and naphthoyl chloride.
As the substance (S) comprising the sole precursor of a functional group capable of reacting with amine groups and isocyanate groups, any substance comprising two adjacent carboxylic acids, in particular trimellitic acid and maleic acid, may be mentioned.

The substance (S) preferably contains only one functional group capable of reacting with amine groups and isocyanate groups, or only one precursor of said functional group.
The substance (S) more preferably contains only one precursor of functional groups capable of reacting with amine groups and isocyanate groups.
Substance (S) may be aliphatic or aromatic. Preferably it is aromatic.
The most preferred substance (S) is trimellitic acid. Excellent results were obtained when trimellitic acid was used as the only substance (S).
The amount of substance (S), particularly the amount of trimellitic acid, is preferably 1.5 mol% or more, more preferably 2 mol% or more, and more preferably, based on the total number of moles of trimellitic anhydride monobasic acid halide and substance (S). Preferably it is 2.5 mol% or more. Furthermore, the amount of substance (S) is advantageously 25 mol% or less, preferably 15 mol% or less, more preferably 10 mol%, based on the total number of moles of trimellitic monobasic acid halide and substance (S). Hereinafter, it is more preferably 8 mol% or less.

The aromatic polyamide-imide advantageously has an intrinsic viscosity (IV) of 0.60 or less, preferably 0.55 or less and more preferably 0.50 or less. Furthermore, it is advantageously 0.20 or more, preferably 0.25 or more and more preferably 0.30 or more. Intrinsic viscosity measurements are performed according to ASTM D2857, ASTM D5336 and ASTM D52251 at 25 ° C. using 1-methyl-2-pyrrolidinone (NMP) in a Schott Gerate Viscometer Instrument (AVS 440).
The aromatic polyamide-imide has an average molecular weight (Mw) of advantageously 40,000 g / mol or less, preferably 35,000 g / mol or less and more preferably 30,000 g / mol or less. Furthermore, advantageously in a DMF solution containing at least 10,000 g / mol, preferably at least 12,000 g / mol and more preferably at least 15,000 g / mol and containing 0.1 M LiBr (dissolved at 100 ° C.) at room temperature by GPC. Measured using polystyrene calibration and corrected with NMR data to give complete values.

  The polymer composition (C) comprises at least 40% by weight of at least one aromatic polyamide-imide, based on the total weight of the polymer composition (C). The aromatic polyamide-imide is preferably 85% by mass or more, more preferably 90% by mass or more, more preferably 95% by mass or more and most preferably 99% by mass based on the total mass of the polymer composition (C). It is contained in the polymer composition (C) in the above amount.

External lubricant The polymer composition (C) preferably comprises an external lubricant. Any external lubricant is in principle suitable as long as it has no detrimental effect on the process and the film extruded therefrom.
The external lubricant is preferably a fluorocarbon polymer. In the present invention, the fluorocarbon polymer is based on at least one ethylenically unsaturated monomer (hereinafter “fluorinated monomer”) in which more than 50 mol% of the repeating units contain at least one fluorine atom, based on the total number of moles of repeating units. ) Is intended to mean any polymer resulting from.
The fluorocarbon polymer preferably contains more than 75% by weight, more preferably more than 90% by weight fluorine or monomer-derived repeating units, more preferably more than 97% by weight fluorine based on the total number of moles of repeating units. Containing repeating units derived from the monomer.

The fluorocarbon polymer preferably comprises repeating units derived from vinylidene fluoride (VF ₂ ) or tetrafluoroethylene (TFE). Preferably, the fluorocarbon polymer is composed of repeating units arising from vinylidene fluoride (VF ₂₎ or tetrafluoroethylene (TFE), and VF ₂ or at least one other fluorinated monomer other than TFE, VF ₂ or TFE Depending on which is used as the base monomer. Other fluorinated monomers include vinylidene fluoride (or VF ₂ when TFE is used as the base monomer); trifluoroethylene; chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (or TFE when VF ₂ is used as the base monomer); hexafluoropropylene (HFP); octafluorobutene; perfluoro (alkyl vinyl) ether, such as perfluoro (methyl vinyl) ether (PMVE), perfluoro (ethyl vinyl) ether (PEVE) And perfluoro (propyl vinyl) ether (PPVE); perfluoro (1,3-dioxole); perfluoro (2,2dimethyl-1,3-dioxole) (PDD); formula CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ The product of CF ₂ X, where X is —SO ₂ F, —CO ₂ H, —CH ₂ OH, —CH ₂ OCN or —CH ₂ OPO ₃ H; the formula CF ₂ = CFOCF ₂ CF ₂ SO product ₂ F; formula F (CF ₂₎ the product of _n CH ₂ OCF = CF _2, Among, n represents is 1, 2, 3, 4 or 5; product of formula _{R 1 CH 2 OCF = CF 2} , wherein, R ₁ is hydrogen or F (CF _{2) z, z} is 1, 2, 3 or 4; product of formula R ₃ OCF═CH ₂ , wherein R ₃ is F (CF ₂ ) _z and z is 1, 2, 3 or 4; perfluorobutylethylene ( PFBE); 3,3,3-trifluoropropene and 2trifluoromethyl-3,3,3-trifluoro-1-propene.

More preferably, the external lubricant is a homopolymer of tetrafluoroethylene or a copolymer in which the repeating units are derived from vinylidene fluoride (VF ₂ ) and hexafluoropropylene (HFP). If this second, VF ₂ / HFP copolymer, based on the total moles of repeating units, preferably at least 50 mol%, more preferably at least 60 mole% of the VF _2, and preferably at most 30 mol%, further Preferably it consists of at most 40 mol% HFP. Furthermore, VF ₂ / HFP copolymer, based on the total moles of repeating units, preferably at most 95 mol%, more preferably at most be 85 mole percent VF _2, preferably at least 5 mol% and more preferably at least Consists of 15 mol% HFP.

Excellent results, Dyneon PTFE commercially available from 3M ^TM PA5956, Solvay Solexis commercially available from tradename Tecnoflon (R) NM fluoroelastomer sold 60-85 mole% of VF ₂ and 40 It was obtained with vinylidene fluoride (VF ₂ ) -hexafluoropropylene (HFP) copolymer consisting of ˜15 mol% HFP, or a mixture thereof.
Surprisingly, the use of an external lubricant not only reduces the adhesion between the polymer and the extruder barrel and die surface as taught in U.S. Pat. It has been found to contribute to reducing and improving film thickness consistency.

The external lubricant, in particular the fluorocarbon polymer, is preferably contained in the polymer composition (C) in an amount of at least 0.1% by weight and more preferably at least 0.3% by weight, based on the total weight of the polymer composition. Furthermore, it is preferably contained in the polymer composition (C) in an amount of preferably at most 2% by mass and more preferably at most 1% by mass based on the total mass of the polymer composition.
The external lubricant preferably has an average molecular weight of no more than 700,000 (measured by conventional GPC technology).
The external lubricant, in particular the fluorocarbon polymer, is preferably evenly distributed in the matrix formed by the polymer composition (C).

  The polymer composition (C) may contain other conventional additives of aromatic polyamide-imide compositions as long as their properties and their amounts do not impair the desired properties. Non-limiting examples of the additive include adhesion promoter, antioxidant, antistatic agent, carbon black, carbon fiber, compatibilizer, curing agent, dye, extended filler, flame retardant, glass fiber, metal Includes particles, release agents, pigments, plasticizers, reinforcing fillers, rubber, silica, smoke retardants, reinforcing agents, UV absorbers, and the like, and mixtures thereof.

  The polymer composition (C) generally comprises 0-5% by weight of at least one solvent of aromatic polyamide-imide. The term “aromatic polyamide-imide solvent” is intended to mean a normally solvent substance capable of dissolving the aromatic polyamide-imide. Typical solvents for the aromatic polyamide-imides of the present invention are 1-methyl-2-pyrrolidinone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) or other dipolar aprotic It is a sex solvent. For example, NMP needs to be heated to about 100 ° C. to dissolve the aromatic polyamide-imide, but once dissolved, the solution can be cooled without any effect on the solubility of the polymer. Preferably, the polymer composition (C) is essentially free of solvent. Highly preferably free of solvent.

Extrusion Method The film (F) is usually extruded by an extruder, which includes a barrel and an extrusion die. The extruder may contain a single barrel, or mostly a plurality of barrels.
The method of the invention is preferably:
(i) supplying the polymer composition (C) to the feed end of the barrel of the extruder;
including.

  Both single screw and twin screw extruders can give good results. Normally, the feed end of the barrel where powdered or pelletized polymer and possibly other materials such as fillers, additives and external lubricants are delivered to the hopper from where they are carried forward and mixed To supply. The polymer composition (C) is preferably fed to the extruder at a feed rate of 7 Lb / hour (3.17 kg / hour) or more, and the feed rate preferably does not exceed 12 Lb / hour (5.44 kg / hour). Screws with a compression ratio of 1: 1 to 3: 1 can be used continuously in the film extrusion process without significant differences. Both undersupply and oversupply are advantageously used, and films as thin as 1 mil (25.4 μm) can be produced. It is also advantageous to operate the screw at a low speed, typically 100 rpm or less and preferably 60 rpm or less. Nevertheless, the screw of the film extruder is preferably operated at 10 rpm or more, more preferably 14 rpm or more.

(ii) A step of melting the polymer composition (C) between the screw blades of the extruder to form a melt (M) of the polymer composition (C).
Typically, the material is plasticized by frictional heat generated by the rotary screw of the extruder and external heat applied through the barrel. The barrel temperature of the extruder is advantageously 250 ° C. or higher, preferably 300 ° C. or higher and more preferably 325 ° C. or higher. Further, it is generally less than 730 ° F. (387.8 ° C.) and preferably less than 705 ° F. (373.9 ° C.). However, good results can be obtained at barrel temperatures of about 450 ° F. (232 ° C.) to about 600 ° F. (316 ° C.) when the extruder is a co-rotating intermesh twin screw extruder. In general, screw movement advances the material along the machine and melts and mixes the polymer and in some cases additives while applying shear.

(iii) passing the melt (C) through the melting channel of the extrusion die, the extrusion die being attached to the outlet of the extruder.
The molten material remains in the extruder as a result of screw action, typically through an oval or circular melt channel.
(iv) A step of heating the extrusion die and holding the polymer composition (C) as a melt.
The die temperature is generally at least 680 ° F. (360.0 ° C.), but when the die temperature is above 730 ° F. (387.8 ° C.), the material often begins to decompose. Thus, the die temperature of the extruder is advantageously less than 730 ° F. (387.8 ° C.), preferably less than 705 ° F. (373.9 ° C.). Further, the temperature of the extrusion die is advantageously 645 ° F. (340.5 ° C.) or higher, preferably 670 ° F. (354.4 ° C.) or higher. The pressure of the extrusion die is generally comprised between 700 and 2500 psi (48.3 to 172.4 bar).

(v) passing the melt (M) through the melt channel, the melt channel having a profile that gives the melt (M) a constantly increasing shear rate.
(vi) a step of extruding the melt (M) outside the outlet of the extrusion die, the outlet having a shape that forms a film in a molten form.
The molten material generally enters a final extrusion die that gives the film its shape. It is also preferable to adjust the die adapter to reduce the residence time between the screw tip and the die.
(vii) a step of providing a film by extruding the molten product from an extrusion die and then solidifying it.
Solidification is usually caused by cooling. The film can be cooled by a number of methods. Air cooling is preferred.
The method advantageously further comprises a step consisting of pelletizing the polymer composition (C) prior to step (i) feeding the polymer composition (C) to the extruder. During this process, it is advantageous to operate the extruder preferably at a low speed of 60 rpm or less.

  In a second aspect, the invention relates to a film obtainable by the above method. The film can be obtained in particular by extrusion, using different types of extruders, in particular twin screw or single screw extruders. The film obtained by the method of the present invention is preferably identical to film (F), very preferably according to all preferred properties of film (F), in particular its thickness, regardless of priority. The film is obtained by other methods and retains the same or substantially the same characteristics characterized by film (F).

The film (F) produced by the method of the present invention or the film obtainable by the method is useful for many applications, such as electrical and electronic insulation applications, such as wire and cable tape, flexible printed circuit boards, motors. Includes slot liners, magnet wire insulators, transformers and capacitor insulators. They can also be used in friction and wear applications such as metal-polymer bushings and bearings.
A significant advantage of the process of the present invention is that it is a high quality extruded very thin film (as thin as 25 μm) from a polymer composition comprising well over 80% by weight of aromatic polyamide-imide essentially free of solvent. ). Such beneficial advantages have not been achieved with any prior art extrusion process.
The following examples are included to provide further guidance to those skilled in the art in practicing the present invention. The provided examples are merely representative of the work that contributes to the teaching of the application. Accordingly, these examples are not intended to limit the invention as defined in the claims in any manner.
Excellent results have been obtained using the methods substantially exemplified herein.

Examples The following raw materials The raw materials are:
Aromatic polyamide-imide (PAI) powder produced by a process comprising polycondensation reaction of trimellitic acid chloride, 4,4′-diaminodiphenyl ether and m-phenylenediamine, and trimellitic acid.
Prepare three grades (PAI 1, PAI 2 and PAI 3), differing only in the amount of trimellitic acid;
PTFE Dyneon ^TM PA5956, tetrafluoroethylene homopolymer commercially available from 3M;
Tecnoflon® NM, a fluoroelastomer made of VF ₂ / HFP copolymer commercially available from Solvay Solexis;
Magnesium oxide commercially available from Kyowa as KM-3150.

Six polymer compositions (samples) were prepared in the form of pellets with a Berstorff B extruder, using the same pelletizing compounding conditions:
Table 1: Pelletizing conditions

  The ingredients of each formulation were mixed together during the pelletization process. The screw speed was 60 rpm. Three grades of PAI, characterized by using different amounts of trimellitic acid, are summarized in the first row of Table 2. They had an intrinsic viscosity of 0.486 dL / g for PAI 1, 0.699 dL / g for PAI 2 and 0.468 dL / g for PAI 3 (measured as defined in the description center of the invention). ).

Table 2: Properties and amounts of the components of the polymer composition (sample)

  Subsequently, a film was prepared from the six polymer compositions (samples). All film extrusions were performed on an Egan single screw extruder, fitted with a 15.24 cm (6 inch) film die and used an underfeed mode. The conditions used are summarized in Table 3. The screw speed was 60 rpm. All films were cured at 500 ° F. (260 ° C.) for 4 hours.

Table 3: Film extrusion conditions

  Films from Samples 1, 2 and 3 were extruded with a 2.3: 1 screw profile. Also, the film from Sample 1 was extruded using a 1: 1 screw profile (hereinafter “1a”). Experiments with Sample 1 (1 and 1a) in Table 4 using PAI 1 of the present invention (TMA = 3.0 based on total moles of trimellitic monobasic acid halide and trimellitic acid) are very good looking thin films The experiment with sample 2 using PAI 2 (TMA with only 0.3%) failed due to high die pressure (> 4300 psi). This indicated that the screw profile had no effect on the quality of the film obtained. Increasing the amount of TMA from 3.0% to 5.5% (PAI 3) led to the extrusion of a good looking film as thin as 25 μm (Sample 3).

  Surprisingly, the film obtained according to the invention was characterized by several anisotropic properties (see Table 4). Properties such as tensile strength, tensile elongation and tensile modulus along the flow direction (MD) were superior to the cross direction (TD).

Table 4: Film properties

  Some other films were extruded from polymer compositions containing Tecnoflon®, magnesium oxide and finally PTFE (samples 4, 5 and 6 in Table 5). Film thicknesses of 50 μm or less were obtained characterized by some additional anisotropic properties.

Table 5: Film properties

Again, properties such as tensile strength, tensile elongation and tensile modulus along the flow direction (MD) were superior to those in the transverse direction (TD). The linear thermal expansion coefficient (CLTE) follows a similar trend. Surprisingly, the properties of sample 6 were found to be more consistent than the others.
The present invention will be described with reference to preferred and exemplary embodiments, but is not limited thereto. Those skilled in the art will recognize that various modifications can be made without departing from the scope of the invention as defined in the claims.

Claims (28)

A method for extruding a film (F) having a thickness of 1000 μm or less from a polymer composition (C), wherein the polymer composition (C) is at least 40 based on the total mass of the polymer composition (C). % By weight of at least one aromatic polyamide-imide, the aromatic polyamide-imide comprising:
Trimellitic anhydride monobasic acid halide;
At least one comonomer selected from diamines and diisocyanates, and the only functional group capable of reacting with either an anhydride group and an acid halide group on the one hand or an amine group and an isocyanate group on the other hand, or the only said functional group At least one substance (S) comprising a precursor of
Produced by a process comprising a polycondensation reaction of
The method wherein the amount of substance (S) is 1 mol% or more based on the total number of moles of trimellitic monobasic acid halide and substance (S).   A method for extruding a film (F) having a thickness of 1000 μm or less from a polymer composition (C), wherein the polymer composition (C) is at least 40 based on the total mass of the polymer composition (C). % By weight of at least one aromatic polyamide-imide, wherein the aromatic polyamide-imide is selected from (i) a combination of trimellitic anhydride monobasic acid halide and trimellitic acid monomer, and (ii) diamine and diisocyanate Wherein the amount of trimellitic acid is 2 mol% or more based on the total number of moles of acid monomer.   The method of claim 1 or 2, wherein the film (F) is extruded in an extruder, the extruder comprising a barrel and an extrusion die. (i) supplying the polymer composition (C) to the supply end of the barrel of the extruder;
(ii) melting the polymer composition (C) between the blades of the screw of the extruder to form a melt (M) of the polymer composition (C);
(iii) passing the melt (C) through the melting channel of the extrusion die, the extrusion die being attached to the outlet of the extruder,
(iv) heating the extrusion die and holding the polymer composition (C) as a melt,
(v) passing the melt (M) through the melt channel, the melt channel having a profile that provides the melt (M) with an ever increasing shear rate;
(vi) extruding the melt (M) outside the outlet of the extrusion die, the outlet has a shape that forms a film in a molten form,
(vii) solidifying the molten shape after extrusion from an extrusion die to provide a film;
The method of claim 3 comprising:   The method according to claim 4, further comprising the step of pelletizing the polymer composition (C) prior to the step of feeding the polymer composition (C) to an extruder.   6. The extruder of any one of claims 3-5, wherein the extruder is a co-rotating intermesh twin screw extruder and has a barrel temperature of about 450 ° F (232 ° C) to about 600 ° F (316 ° C). the method of.   The method according to any one of claims 3 to 5, wherein the extruder is a co-rotating intermesh single screw extruder.   The method according to any one of claims 3 to 7, wherein the temperature of the extrusion die is 645 ° F (340.5 ° C) or higher.   The method of claim 8, wherein the temperature of the extrusion die is 680 ° F (360.0 ° C) or higher.   The method of any one of claims 3 to 9, wherein the temperature of the extrusion die is less than 730 ° F (387.8 ° C).   The method of claim 10, wherein the temperature of the extrusion die is less than 710 ° F (376.7 ° C).   The method according to any one of claims 3 to 11, wherein the polymer composition (C) is fed to the extruder at a feed rate of 7 Lb / hr (3.17 kg / hr) or more.   The process according to any one of claims 3 to 12, wherein the polymer composition (C) is fed to the extruder at a feed rate of less than 12 Lb / hr (5.44 kg / hr).   14. The method according to any one of claims 1 to 13, wherein the aromatic polyamide-imide has a weight average molecular weight of 40,000 g / mol or less.   The method according to any one of claims 1 and 3 to 14, wherein the amount of the substance (S) is 15 mol% or less based on the total number of moles of trimellitic monobasic acid halide and the substance (S). .   The process according to any one of the preceding claims, wherein the polymer composition (C) comprises at least 85% by weight of aromatic polyamide-imide, based on the total weight of the polymer composition (C).   The method according to any one of claims 1 to 16, wherein the thickness of the film (F) is 100 µm or less.   The method according to claim 17, wherein the thickness of the film (F) is 55 μm or less.   The method according to any one of claims 1 to 18, wherein the polymer composition (C) further comprises an external lubricant.   The method of claim 19, wherein the external lubricant is a fluorocarbon polymer.   21. The method of claim 20, wherein the fluorocarbon polymer is a homopolymer of tetrafluoroethylene. Fluorocarbon polymers, vinylidene fluoride consisting of 60 to 85 mol% of VF ₂ and 40 to 15 mole% of HFP (VF ₂₎ - hexafluoropropylene (HFP) copolymer The method of claim 20, wherein. Fluorocarbon polymers, homopolymers, and 60 to 85 mole percent VF ₂ and 40 to 15 mole% of vinylidene fluoride consisting HFP of tetrafluoroethylene (VF ₂₎ - is a mixture of hexafluoropropylene (HFP) copolymer, The method of claim 20.   The method according to any one of claims 19 to 23, wherein the external lubricant is contained in the polymer composition (C) in an amount of at least 0.1% by weight, based on the total weight of the polymer composition (C). .   The method according to any one of claims 19 to 24, wherein the external lubricant is contained in the polymer composition (C) in an amount of 1% by mass or less, based on the total mass of the polymer composition (C). .   26. The method according to any one of claims 1 to 25, wherein the polymer composition (C) comprises 0 to 5% by weight of at least one solvent of aromatic polyamide-imide.   The film obtained by the method of any one of Claims 1-26.   28. Use of a film according to claim 27 in an application selected from electrical and electronic insulation applications and friction and wear applications.