JPH06136156A - Aromatic polyamide film and its production - Google Patents

Abstract

PURPOSE:To provide a para-oriented aromatic polyamide film excellent in heat resistance, mechanical strengths, thermal dimensional stability and hygroscopic dimensional stability. CONSTITUTION:A para-oriented aromatic polyamide film substantially consisting of a para-oriented aromatic polyamide of a logarithmic viscosity of 3.5 or above and having a rate [L] of dimensional change of film in at least one direction of below 1020, a Young's modulus of elasticity of film in an arbitrary direction of 500kg/mm<2> or above and an elongation of 30% or above is provided. The above rate [L] of dimensional range is defined as follows: rate of dimensional change [L]=55XalphaW-120Xalphar wherein alphar is the coefficient of thermal expansion (ppm/ deg.C, 30-150 deg.C), alphaW is hygroexpansivity (ppm/%RH, 0-55%RH).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a film of para-oriented aromatic polyamide,
More specifically, a film having excellent mechanical performance in both the longitudinal direction (hereinafter abbreviated as MD direction) and the width direction (hereinafter abbreviated as TD direction) of the film, and further excellent in heat resistance and dimensional stability, and a method for producing the same. It is about.

[0002]

2. Description of the Related Art Para-oriented aromatic polyamides represented by polyparaphenylene terephthalamide (hereinafter referred to as PPTA) have particularly excellent crystallinity and high melting point, and because of their rigid molecular structure, they are heat resistant. It has a high mechanical strength and is a polymer material that has been receiving particular attention in recent years. Fibers spun from a concentrated solution exhibiting its optical anisotropy have been reported to exhibit high strength and modulus,
It has already been implemented industrially.

On the other hand, some applications of PPTA as a film have been proposed. For example, in JP-B-57-17886, an optically anisotropic dope of PPTA is heated just before solidification until it becomes optically isotropic. After that, it is described that a film which is transparent and isotropic in mechanical properties is obtained by solidifying the film. P produced by this method
PTA films have excellent mechanical properties, heat resistance, chemical resistance, etc., and therefore, for example, flexible printed wiring boards (FPC), tape automated bonding (TPC)
Application as an insulating substrate such as a carrier tape for AB) is expected.

In these applications, as the wiring pattern becomes finer, the demand for dimensional accuracy becomes stricter.
A base film having a thermal dimensional change rate and a hygroscopic dimensional change rate close to those of a semiconductor element and a conductive material is demanded. For example, Japanese Patent Laid-Open No. 63-66233 discloses a PPTA film in which the film is kept constant in a wet state. There is disclosed a film in which a dimensional change due to moisture absorption is reduced by stretching the film at a magnification ratio or more and heat-treating it. However, since this film has a low coefficient of thermal expansion as compared with a conductive material such as copper, there is a problem that curling occurs due to a difference in dimensional change when the film and the copper foil are laminated.

On the other hand, for example, Japanese Patent Publication No. 56-45421 proposes a film in which a unit in which a halogen is introduced into an aromatic nucleus of para-oriented polyamide is copolymerized to reduce a dimensional change in moisture absorption. However, such a copolymer film has a defect that, for example, the crystallinity of the para-oriented aromatic polyamide is impaired, or that the heat shrinkage rate at a high temperature is large. Further, at a high temperature, there is a disadvantage that the surrounding metal or the like is corroded due to the elimination of the introduced halogen.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to a film having excellent mechanical performance and heat resistance, which uses a para-oriented aromatic polyamide, and a method for producing the film. In particular, a metal having a thermal dimensional change rate such as copper is used. It is an object of the present invention to provide a film having excellent moisture absorption dimensional stability and a method for producing the same.

[0007]

Means for Solving the Problems As a result of intensive studies to obtain a film that meets the above-mentioned object, the present inventors have found that a film in a wet state is dried while shrinking and then hot-stretched. The inventors have found that the thermal dimensional change rate and the moisture absorption dimensional change rate can be controlled, and further studies have been completed to complete the present invention.

That is, the first aspect of the present invention is that the logarithmic viscosity is 3.5.
A film consisting essentially of the above para-oriented aromatic polyamide, wherein the dimensional change rate [L] in at least one direction within the film plane is less than 1020, and the Young's modulus in any direction within the plane of the film is Para-Oriented Aromatic Polyamide Film Characterized by 500 Kg / mm ² or More and Elongation of 30% or More However, dimensional change rate [L] = 55 × α _W −120 × α _T α _T : coefficient of thermal expansion (Ppm / ° C., 30 to 150 ° C.) α _W : Hygroscopic expansion coefficient (ppm /% RH, 0 to 55% RH), the second is a para-oriented aromatic polyamide having a logarithmic viscosity of 3.5 or more. In a method for producing a film, which comprises casting an optically anisotropic dope consisting essentially of 95 parts by weight or more of sulfuric acid on a supporting surface, converting the dope into an optically isotropic mixture by moisture absorption and / or heating and then solidifying the same. , Wet cloth after coagulation and washing When the rum is dried, it is contracted in at least one direction to 0.95 times or less and in all directions by contracted by 0.6 times or more, and then dried, and then in at least one direction in a temperature range of 250 to 450 ° C. A method for producing a para-oriented aromatic polyamide film, which comprises heat-setting at a temperature of 300 ° C. or higher after stretching to 0.05 times or more and not exceeding 2 times in all directions. is there.

The para-oriented aromatic polyamide used in the present invention is substantially composed of a unit selected from the group consisting of the following constitutional units. —NH—Ar ₁ —NH— (1) —CO—Ar ₂ —CO— (2) —NH—Ar ₃ —CO— (3) where Ar ₁ , Ar ₂ and Ar ₃ are each at least one. A divalent group containing an aromatic ring, (1) and (2)
Are substantially equimolar when present in the polymer.

In the present invention, in order to ensure good mechanical performance and dimensional stability, Ar ₁ , Ar ₂ and A
Each r ₃ needs to be a para-oriented group. Here, the para-orientation type means that the binding direction of the main chain in the aromatic ring is located in the para position, or in the residue composed of two or more aromatic rings, the binding directions of the main chains at both ends are coaxial or parallel. Means there is.

Typical examples of such a divalent aromatic group include:

[0012]

[Chemical 1]

Here, X is --O--, --CH _2- , --S
_{O 2 -, - S -,} - CO- selected from among. Further, some hydrogen atoms of these aromatic rings may be substituted with an alkyl group, an alkoxy group or the like, but in consideration of the heat resistance of the film, a corrosive gas may be generated at a high temperature. It is preferably not substituted with a polar substituent such as halogen, nitro or sulfone.

Ar ₁ , Ar ₂ and Ar ₃ are all 2
There may be more than one species, and they may be the same or different from each other. The polymer used in the present invention can be produced from a diamine, a dicarboxylic acid or an aminocarboxylic acid corresponding to each unit by a method known so far. Specifically, a method of first deriving a carboxylic acid group into an acid halide, an acid imidazole, an ester, etc. and then reacting it with an amino group is used, and the type of polymerization is also a so-called low temperature solution polymerization method, interfacial polymerization method, melt polymerization method. , Solid phase polymerization method, etc. can be used.

The aromatic polyamide used in the present invention may be copolymerized with a group other than those described above in an amount of about 10 mol% or less, or may be blended with another polymer. The most typical aromatic polyamide used in the present invention is poly-p-phenylene terephthalamide (PPT).
A) and poly-p-benzamide. If the degree of polymerization of the aromatic polyamide used in the present invention is too low, a film having good mechanical properties, which is the object of the present invention, cannot be obtained, and therefore the logarithmic viscosity ηinh (sulfuric acid 1
The polymerization degree is selected so that 0.2 g of the polymer is dissolved in 00 ml to give a value measured at 30 ° C.

Such a film having isotropically high mechanical performance can be obtained by wet film formation from a liquid crystal stock solution of para-oriented aromatic polyamide typified by PPTA. However, a film obtained by directly solidifying a liquid crystal solution of PPTA has a large anisotropy of tensile modulus and elongation, so that it is extremely difficult to obtain isotropic physical properties. A film obtained by extruding in the state, optically isotropy and then solidifying is preferably used.

The thickness of the film of the present invention is 4 μm or more, 1
00μ or less is a preferable range, and 6μ or more and 75μ or less is more preferable. It is important for the film of the present invention that the dimensional change rate [L] in at least one direction within the film plane is less than 1020. This is for the following reason. FP
When a film is used as a carrier tape for C, TAB, etc., there arises a problem that curling occurs due to a difference in dimensional change between a copper plate to be bonded and a film. Usually, a thermosetting adhesive is used to bond the copper plate. Therefore, the curl of the copper clad board is in the state when the adhesive is cured (150 ° C,
0% RH) and normal copper-clad board usage conditions (30 ° C, 55% R)
It is determined by the difference in dimensional change between the copper plate and the film in H), and the smaller the difference in dimensional change, the less the curl. This difference in dimensional change [A (ppm)] is expressed by the following equation using the thermal expansion coefficient α _T and the hygroscopic expansion coefficient α _W.

[0018]

[Equation 1]

As a result of examination, the difference in dimensional change [A] is 300.
If it was less than 0 ppm, the curl of the copper clad plate was good.
Therefore, by using a film having α _W and α _r satisfying the following equation, it becomes possible to produce a copper clad plate having a good curl property. 55 × α _W −120 × α _r +1980 <3000 That is, it is necessary that the dimensional change rate [L] in the following equation is less than 1020.

The lower limit of [L] = 55 × α _W −120 × α _r [L] is not particularly limited, but it is preferably −4000 or more in consideration of the above formula. Also, α _W ,
α _r is not particularly limited either, but α _W is −20 to 70 ppm /% RH, α _r when considering from the copper plating process.
Is preferably in the range of -20 to 50 ppm / ° C.

The film of the present invention has a tensile modulus of 500.
It must be kg / mm ² or more, 600 Kg / mm ² or more. The film of the present invention needs to have an elongation of 30% or more in order to ensure handleability when used. The film of the present invention is produced, for example, by the following method.

First, the aromatic polyamide is dissolved in a solvent.
As the solvent, strong acids such as concentrated sulfuric acid, chlorosulfuric acid, fluorosulfuric acid, methanesulfonic acid and trifluoromethanesulfonic acid are used. The polymer concentration in the stock solution is room temperature,
It is preferably used at a concentration above the optical anisotropy at a temperature of not less than that, specifically at about 10% by weight or more, preferably about 12% by weight to 15% by weight.
When preparing the stock solution, it is preferable to cut off the air, and it is usually carried out in an atmosphere of an inert gas such as nitrogen or argon or in a vacuum. The stock solution can be prepared by heating if necessary, and can be subjected to defoaming, filtration, and the like.

The thus-prepared stock solution may be cast into a film by using a doctor knife or by pushing it out from a die and coagulated as it is. In particular, when a liquid crystal stock solution is used, heating or It is preferable that the undiluted casting solution be converted into an optically isotropic solution by moisture absorption and then solidified. It is preferred that the stock solution avoid contact with air or oxygen during casting or while the liquid crystal is optically isotropic.

As the coagulating liquid, water, dilute sulfuric acid, sodium hydroxide solution, sodium chloride solution or the like can be used. The temperature of the coagulation bath is not particularly limited and is usually in the range of about -10 ° C to 50 ° C. Since the coagulated film contains acid as it is, it is necessary to wash and remove the acid component as much as possible in order to produce a film in which mechanical properties are not significantly deteriorated by heating. Specifically, it is desirable to remove the acid content up to 500 ppm or less. Water is usually used as the cleaning liquid, but if necessary, warm water may be used, or neutralization cleaning with an alkaline aqueous solution may be performed, followed by cleaning with water or the like. The cleaning is performed by, for example, running in the cleaning liquid or spraying the cleaning liquid.

The washed film is then dried,
In the present invention, it is very important to dry while shrinking in a specific range, and by drying while shrinking, it becomes possible to control the thermal dimensional change rate as compared with a conventional film, and improve the elongation. It is also possible. Here, drying while shrinking means drying while making the area of the film smaller than in the gel film state.

The shrinking method can be easily performed by utilizing the shrinking force of the film itself. The shrinkage ratio must be 0.95 times or less in at least one direction, and the shrinkage ratio must be 0.6 times or more in all directions. If it is less than 0.6 times, the shrinking force becomes extremely weak, and partial shrinkage of the film causes partial wrinkling of the film, impairing the flatness and curling. If the shrinkage is not 0.95 times or less during drying, the thermal dimensional change rate becomes too small and the desired dimensional stability cannot be obtained, which is not preferable.

The shrinking and drying can be accomplished, for example, by shrinking between the rolls and drying, or by using a tenter dryer to shrink and dry. Other conditions relating to drying are not particularly limited, and methods such as heated air (air, nitrogen, argon, etc.) and room temperature gas, methods of utilizing radiant heat from electric heaters and infrared lamps, dielectric heating methods, etc. You can freely choose from. The drying temperature may be room temperature or higher, but is preferably 100 ° C. or higher in consideration of the drying speed. The maximum drying temperature is not particularly limited, but is preferably 400 ° C. or lower in consideration of the energy of drying, the decomposability of the polymer, and the like.

The dried film then needs to be heat stretched. The hot stretching is carried out in the range of 250 to 450 ° C. by stretching 1.05 times or more in one direction or two directions perpendicular to each other and stretching ratios in all directions not exceeding 2.0. Stretching may be carried out by any one of a method of stretching in only one direction of the film, a method of stretching in one direction and then stretching in a direction perpendicular to the stretching direction, or a method of stretching in two directions perpendicular to each other. Good. Stretching temperature is 25
If it is less than 0 ° C, stretching is difficult, and if it exceeds 450 ° C,
It is not preferable because it is brittle due to decomposition of the polymer and cannot be stretched. More preferably, it is better to stretch at 300 to 400 ° C.

If the stretching ratio is less than 1.05 times in all directions, the rate of dimensional change in humidity becomes large and the desired dimensional stability cannot be obtained, which is not preferable. If the stretching ratio exceeds 2.0 even in one direction, the film may be broken, which is not preferable. As a means for stretching, a method of stretching using a pair of rolls, a method of stretching using a tenter, and a method of stretching using both of them.
Conventional techniques such as a method using a biaxial stretching machine can be used.

In these stretching methods, the stretching speed is from 1 to
A range of 100% / min is preferred. Further, it is preferable to preheat the film to such an extent that the film is not highly crystallized before the stretching because smooth stretching can be performed. The film thus obtained must be heat-set at a temperature of 300 ° C. or higher under tension or under contraction. When heat setting is carried out at a temperature of less than 300 ° C., the rate of dimensional change in humidity becomes large, and a film having a desired dimensional change cannot be obtained. The upper limit of the heat setting temperature is not particularly limited, but in consideration of polymer decomposition and the like, it is preferably performed at 500 ° C. or lower.

[0031]

The present invention will be described in more detail with reference to the following examples. The thickness of the film was measured with a dial gauge having a measuring surface with a diameter of 2 mm. The strength and elongation were measured by using a constant speed elongation type strength and strength tester at a measuring length of 100 mm and a tensile speed of 50 mm / min in the circumferential direction.
The coefficient of thermal expansion of the film was measured using a thermomechanical analyzer (TMA). The humidity expansion coefficient of the film is about 5
Mark two points at an interval of cm, dry the film at 200 ° C. for 2 hours, and set the distance between the two points to 55.
It was determined by measuring with a measuring microscope the distance between two points after the moisture absorption completely reached equilibrium after being left in the% RH atmosphere for one week or more. Further, the rate of dimensional change was calculated from Equation 1 using the values of the coefficient of thermal expansion and the coefficient of hygroscopic expansion.

[0032]

Example 1 ηinh = 6.% in concentrated sulfuric acid having a concentration of 99.5%.
1 of PPTA was melted at 60 ° C. to prepare a stock solution having a polymer concentration of 12%. The stock solution was degassed under vacuum while maintaining it at 60 ° C. The filter is passed from the tank, the liquid is sent by the gear pump, and the dope is cast on the tantalum belt from the T die having the slit of 0.3mmX300mm.
The casting dope was optically isotropically blown with air having a relative humidity of about 12% and a temperature of about 105 ° C., and the casting dope was introduced into water at 5 ° C. together with the belt to be solidified. Then, the coagulated film was peeled off from the belt, warm water at about 30 ° C., and then 0.5% NaO.
In H aqueous solution, run in water at room temperature to wash,
A gel film was obtained.

This gel film was used for T with a tenter.
While shrinking in the D direction, drying was performed at 200 ° C.
Then, using a tenter, stretching was performed in the TD direction at 320 ° C. After that, heat setting was performed at 320 ° C. for 1 minute.
Table 1 shows the shrinkage ratio and the draw ratio at this time. The physical properties are shown in Table 2. As shown in the table, this film had an excellent dimensional change rate and physical properties.

[0034]

Examples 2 to 5 While shrinking the gel film obtained by the same method as in Example 1 in two directions orthogonal to each other between rolls,
It was dried at 200 ° C. Next, after stretching in the MD direction using a hot stretching roll, stretching was performed in the TD direction using a tenter. After that, heat setting was performed at 350 ° C. for 1 minute. Table 1 shows the shrinkage ratio, the draw ratio and the draw temperature at this time. The physical properties are shown in Table 2. As shown in the table, this film had an excellent dimensional change rate and physical properties.

[0035]

Examples 6 to 7 The gel film obtained by the same method as in Example 1 was dried at 200 ° C. while shrinking in two orthogonal directions using a biaxial stretching machine. Then, using a hot stretching machine, stretching was performed in the MD and TD directions. Then 350
Heat setting was performed at 0 ° C. for 1 minute. Table 1 shows the shrinkage ratio, the draw ratio and the draw temperature at this time. The physical properties are shown in Table 2.
As shown in the table, this film had an excellent dimensional change rate and physical properties.

[0036]

Comparative Example 1 The gel film obtained by the same method as in Example 1 was dried and shrunk by 0.9 times in the MD direction and 0.5 times in the TD direction while shrinking in two orthogonal directions using a biaxial stretching machine. I went. Under this condition, since the shrinkage ratio is large, the dry film was corrugated and a flat film could not be obtained.

[0037]

Comparative Example 2 A film was produced in the same manner as in Example 6 except that 0.97 times dry shrinkage was performed in both MD and TD. The stretching ratio and stretching temperature at this time are shown in Table 1, and the physical properties are shown in Table 2.
Shown in. Under this condition, since the shrinkage ratio is small, α _T becomes too small, and the dimensional change rate L becomes large.

[0038]

[Comparative Example 3] A film was produced in the same manner as in Example 6 except that hot stretching was performed 1.02 times in both MD and TD. The stretching ratio and stretching temperature at this time are shown in Table 1, and the physical properties are shown in Table 2.
Shown in. Under this condition, since the draw ratio was small, α _w did not decrease, and the dimensional change rate L was considerably large.

[0039]

COMPARATIVE EXAMPLE 4 A shrinkage-dried film obtained in the same manner as in Example 2 was stretched 2.1 times in the MD direction.
The film broke on the way.

[0040]

Comparative Example 5 When a shrink-dried film obtained by the same method as in Example 2 was tried to be stretched 1.05 times in the MD direction at 230 ° C., the film broke midway.

[0041]

Comparative Example 6 Example 6 except that hot stretching is performed at 470 ° C.
A film was produced in the same manner as in. Draw ratio at this time,
The stretching temperature is shown in Table 1. This film has a low elongation,
It was shabby and could not be measured for various physical properties.

[0042]

Comparative Example 7 The gel film obtained by the same method as in Example 1 was stretched 1.35 times in the MD direction using a roll stretching machine in the gel film state, and then 1.35 in the TD direction using a tenter. Double stretching was performed. After that, it was dried at 200 ° C. for a fixed length and then heat-set at 350 ° C. for 1 minute.
The physical properties of this film are shown in Table 2. As shown in the table, α _T was too low and the dimensional change rate was poor.

[0043]

Comparative Example 8 The gel film obtained by the same method as in Example 1 was used as a gel film in MD and TD using a tenter.
1.15 times stretching was performed in the direction. Then at a fixed length of 370 ℃
After being hot-air dried at 320 ° C., it was heat-fixed at 320 ° C. by shrinking it by 5% in the MD and TD directions. The physical properties of this film are shown in Table 2. As shown in the table, α _w did not decrease so much, and the dimensional change rate was poor.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

INDUSTRIAL APPLICABILITY The film of the present invention has excellent heat resistance, mechanical performance, chemical resistance, etc. possessed by para-oriented aromatic polyamide, and in addition to the thermal dimensional change rate and hygroscopic expansion as shown in Examples. The feature is that the rate can be controlled. For this reason, this film is an insulating substrate such as a flexible printed wiring board (FPC), a carrier tape for tape automated bonding (TAB), a base of a magnetic recording medium such as a magnetic tape or a magnetic disk, which requires particularly dimensional accuracy. It is useful as an insulating material for electric devices such as films. In addition to this, since this film has a thermal expansion coefficient relatively close to that of a metal, curling is less likely to occur in applications such as FPC, TAB, etc., where it is laminated to a metal, and the elongation is large, so handling in the process is good. It has the feature of being.

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Claims (2)

[Claims] 1. A film consisting essentially of a para-oriented aromatic polyamide having a logarithmic viscosity of 3.5 or more, wherein the dimensional change rate [L] in at least one direction in the plane of the film is 102.
A para-oriented aromatic polyamide film having a Young's modulus of 500 Kg / mm ² or more and an elongation of 30% or more in an in-plane arbitrary direction of the film of less than 0. However, dimensional change rate [L] = 55 × α _W −120 × α _T α _T : thermal expansion coefficient (ppm / ° C., 30 to 150 ° C.) α _W : hygroscopic expansion coefficient (ppm /% RH, 0 to 55%) RH) 2. An optically anisotropic dope consisting essentially of a para-oriented aromatic polyamide having an inherent viscosity of 3.5 or more and sulfuric acid of 95 parts by weight or more is cast on a support surface to absorb moisture and / or In the method for producing a film in which the dope is optically isotropically converted by heating and then coagulated, at least one direction is 0.9 at the time of drying the wet film after coagulation and washing with water.
After shrinking 5 times or less and shrinking 0.6 times or more in all directions and drying, at least one direction becomes 1.05 times or more in a temperature range of 250 to 450 ° C., and all directions are 2 times or more. A process for producing a para-oriented aromatic polyamide film, which comprises heat-setting at a temperature of 300 ° C. or higher after stretching so as not to exceed double.