JPH10114823A - Modified polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a modified polyimide film which has a low water absorption, a high modulus, and a high heat resistance by specifying the surface Si-atom concn., tensile modulus, coefficient of linear thermal expansion, water absorption, and 5% thermal wt. loss temp. of the same. SOLUTION: This film has a surface Si-atom concn. (based on Si atoms bonded to phenyl groups at the film surface) of 1-20%, a tensile modulus of 470-1,000kg/mm<2> , a coefficient of linear thermal expansion of 5×10<-6> -25×10<-6> cm/ cm/ deg.C, a water absorption of 0.5-1.3%, a 5% thermal wt. loss temp. of 500 deg.C or higher, and a thickness of 10-125μm. Si atoms at the film surface are derived from a poly(phenyltrialkoxysilane), etc. The arom. tetracarboxylic acid units of the polyimide structural units in the film are derived from a component contg. at least 50mol% 3,3',4,4'-biphenyltetracarboxylic acid, and diamine units, from a component contg. at least 30mol% p-phenylenediamine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide film having excellent physical properties even under various environments.

[0002]

2. Description of the Related Art Aromatic polyimide films have high heat resistance and are used for various electric and electronic parts, but due to recent demands for higher precision, higher density, and higher productivity. Further, there is a need for an aromatic polyimide film having low water absorption and high elasticity. For this reason, various proposals have been made. For example, fluorine-based monomers for the purpose of low water absorption
Polyimides have been developed, but fluorine-based monomers are very expensive, and fluorine-based monomers have low reactivity and it is difficult to obtain high-molecular-weight polymers. The fact is that the obtained polyimide has not reached the point where it can be used widely. It has also been studied to reduce the water absorption by using aliphatic monomers or silicones, but these polyimide films have a drawback that their elastic modulus is small and their stiffness is weak.

[0003] Further, a molded article comprising a composition of silica and polyimide formed from a hydrolytic condensate of tetraethoxysilane by a sol-gel method for the purpose of increasing the elastic modulus is also known. For example, it is a polyimide molded body described in JP-A-3-287626 and JP-A-7-331069. However, these known polyimide moldings have a disadvantage that the water absorption is increased. In other words, these known polyimide resin moldings could not satisfy the conditions of a certain degree of elasticity or more and low water absorption.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyimide film which does not have the above-mentioned problems, that is, has both a certain degree of elasticity and low water absorption.

[0005]

That is, the present invention provides:
The surface atomic concentration of Si based on Si bonded to a phenyl group on the film surface is 1% (% by weight, the same applies hereinafter), the tensile modulus is 450 kg / mm ² or more, and the linear expansion coefficient is 25 × 10 ⁻⁶ cm. / Cm / ° C or less, and the water absorption is 1.
The present invention relates to a modified polyimide film having a thermogravimetric reduction temperature of 4% or less and a 5% thermal weight loss temperature of 500 ° C or more.

The modified polyimide film of the present invention
Preferably has a thickness of 10-125 μm,
By hydrolysis / polymerization of alkoxysilane compounds containing
Atomic concentration on the surface of the substrate is 1% or more, preferably 1 to 2
0%, tensile modulus is 450kg / cm^TwoAbove, especially 47
0-1000kg / cm^Two, The coefficient of linear expansion is 25 × 10 ^-6
cm / cm / ° C or less, especially 5 × 10^-6~ 25 × 10^-6c
m / cm / ° C, water absorption is 1.4% or less, especially 0.5 to
It is preferable that the polyimide film is 1.3%.
No.

[0007] The Si on the film surface is Si bonded to a phenyl group, and the surface atomic concentration must be 1% or more. Even if the Si surface atom concentration is 1% or more, a polyimide film having low water absorption cannot be obtained with Si bonded to an alkyl group.
%, The water absorption becomes high. Further, unless the film as a whole has high elasticity, it is difficult to use it for applications such as electronic parts and printed parts.

[0008] The modified polyimide film of the present invention is, for example, an organic polar solvent solution of polyamic acid or polyimide (preferably an organic polar solvent solution of polyamic acid) which gives a highly elastic polyimide film.
Then, phenylalkoxysilane, diphenylalkoxysilane or a partial hydrolyzate thereof was added thereto, and the obtained solution composition was cast as a dope for film formation and dried to obtain a self-supporting film. It can be suitably manufactured by a method of forming a polyimide film by heating or the like. During this step, phenylalkoxysilane, diphenylalkoxysilane or its partial hydrolyzate is converted to poly (monophenylsiloxane) or poly (diphenylsiloxane) by heating a small amount of water generated or added in the system and heating.

The aromatic tetracarboxylic acid component which is a constituent unit of the polyimide in the present invention includes aromatic tetracarboxylic acids having a rigid molecular structure, for example, 3,4.
3 ', 4,4'-biphenyltetracarboxylic acid, 2,
3,3 ′, 4′-biphenyltetracarboxylic acid, various isomers of benzophenonetetracarboxylic acid, pyromellitic acid, various isomers of naphthalenetetracarboxylic acid, dianhydrides of those acids, or esters of these acids, Alternatively, their halides (especially fluorinated compounds), their acid dianhydrides, or their acid esterified compounds can be used in combination. In particular, 3,3 ', 4
4'-biphenyltetracarboxylic dianhydride is preferred.

As the aromatic diamine component which is a constituent unit of the polyimide of the present invention, an aromatic diamine having a rigid molecular structure, particularly paraphenylenediamine alone, is preferable, and a part of the aromatic diamine is replaced with another aromatic diamine (for example, meta-diamine). Phenylenediamine, aromatic diamine having a group such as O, propylene, ethylene, methylene, S in the main chain)
It may be replaced with 60 mol% or less.

The other aromatic diamines include metaphenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylpropane,
4'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide and the like can be mentioned.

The organic polar solvent solution of a polyamic acid or polyimide which gives a highly elastic polyimide film is, for example, an aromatic tetracarboxylic acid, an acid dianhydride or an ester of the acid, preferably 3,3 ', 4,4 '
-Biphenyltetracarboxylic dianhydride and an aromatic diamine, preferably paraphenylenediamine, are combined with N, N-dimethylacetamide, N-methyl-2-pyrrolidone (in the case of polyamic acid) or parachlorophenol (of polyimide). In the case of a polyamic acid in an organic polar solvent usually used for the production of a polyimide film such as
It is preferably obtained by polymerizing at 10 to 80 ° C for 1 to 30 hours, and suitably has a logarithmic viscosity of the polymer (measuring temperature: 30 ° C,
Concentration: 0.5 g / 100 ml solvent, solvent: N-methyl-
2-pyrrolidone) 1-5, polymer concentration 15-25
% By weight, and the rotational viscosity (30 ° C.) is 500 to 4500.
Polyamic acid that is poise (imidation ratio: 5% or less)
Obtained as a solution.

In the above method, which is a preferred example of producing the modified polyimide film of the present invention, a phenyl group-containing alkoxysilane compound, preferably a phenylalkoxysilane, is added to an organic polar solvent solution of a polyamic acid.
Diphenylalkoxysilane or its partial hydrolyzate is added and mixed to obtain a polyamic acid solution containing phenylalkoxysilane, diphenylalkoxysilane or its partial hydrolyzate.

As the above-mentioned phenylalkoxysilane, diphenylalkoxysilane or a partial hydrolyzate thereof, for example, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane or a partial hydrolyzate thereof is preferable. Used for These may be used alone or in combination of two or more. Moreover, you may use together with another alkoxysilane. These phenylalkoxysilanes, diphenylalkoxysilanes or partial hydrolysates thereof may be used as they are, and organic polar solvents such as N, N-dimethylformamide,
N, N-dimethylacetamide and N-methyl-2-pyrrolidone may be used after being dissolved.

The amount of the phenyl group-containing alkoxysilane compound to be added is 1 to 100 parts by weight of the polyamic acid.
It is preferably from 0 to 80 parts by weight, particularly preferably from 20 to 70 parts by weight. If the addition amount is too small, the effect of improving the water absorption of the obtained film is small, and if the addition amount is too large, the film becomes brittle, but the film becomes brittle, and only those having extremely low commercial value can be obtained. The amount of water added as required is usually 0 to 200 parts by weight based on 100 parts by weight of the polyamic acid. If the amount of water is too large, the polyamic acid is hydrolyzed, and the physical properties of the obtained film are deteriorated.

Simultaneously or separately with the addition of the phenyl group-containing alkoxysilane compound, preferably 0.01 to 1% by weight of (poly) per 100 parts by weight of polyamic acid.
Phosphorus-containing compounds such as phosphate esters and / or amine salts of phosphate esters and polyamic acid 100
0.1 to 3 parts by weight of inorganic filler such as colloidal silica (preferably 0.005 to 2 parts by weight)
μm) to prepare a polyamic acid solution composition.

The polyamide composition may be used by adding other known additives and the like. For example, antioxidants,
Examples include heat stabilizers, ultraviolet absorbers, inorganic fillers (alumina, talc, carbon, etc.), organic and inorganic pigments, and the like.
These addition amounts are selected in a range where the physical properties do not decrease.

The polyamic acid solution composition prepared as described above is used as a dope for film formation, and preferably has a casting temperature of about 150 ° C. or less, particularly preferably 0 to 120 ° C.
A thin film of the solution is formed by casting on a surface of a support such as a glass plate having a smooth surface, a metal drum or a belt at a casting temperature of the order of about 150 ° C. The following drying temperature, particularly preferably 20 to 14:
A self-supporting solidified film formed by a film-forming method such as a solution casting method, which is dried at a drying temperature of about 0 ° C., preferably for about 0.1 to 1 hour, is obtained.

The above-mentioned solidified film of a polyamic acid self-supporting material is, for example, an aromatic polyamic acid solution in which the above-mentioned high molecular weight aromatic polyamic acid is uniformly dissolved at a concentration of about 2 to 50% by weight. In the composition, pyridine,
Betapicolin, isoquinoline, 3,5-lutidine, 4
A tertiary amine compound such as -methylpyridine or 3-methylpyridine, a chemical conversion agent such as a fatty acid anhydride such as acetic anhydride, and the above-mentioned phosphorus compound, and dissolved (addition order of these corner components). The composition is not particularly limited and may be appropriately selected depending on the stability of the composition and the like.) The composition is preferably used as a dope solution for film formation at about 0 to 150 ° C.
A liquid thin film is formed on the surface of the support at a casting temperature of particularly preferably about 5 to 120 ° C., and the thin film is dried on the support at a drying temperature of preferably about 150 ° C. or less, particularly preferably 20 ° C. A self-supporting solidified film is obtained by a film forming method such as a solution casting method in which drying is performed at a drying temperature of about 140 ° C., preferably for about 0.1 to 1 hour.

The rate of formation of poly (phenyltrialkoxysilane) or poly (diphenyldialkoxysilane) is controlled by the amount of water added, heating conditions, amount of chemical conversion agent, and the like. The self-supporting film is heated to evaporate and remove volatile components such as the solvent, imidize the polyamic acid to an imidation ratio of 95% or more, and hydrolyze and polymerize the phenyl group-containing alkoxysilane.

The above heat treatment is first carried out for about 100 to 40
At a temperature of 0 ° C., the imidization of the polyamic acid and the evaporation / removal of the solvent are carried out for about 0.1 to 5 hours, in particular 0.2 to 3 hours.
It is preferable to perform the treatment gradually over time. In particular, the heat treatment is performed at a relatively low temperature of about 100-170 ° C. for about 1-30 minutes, and then at a temperature of 170-220 ° C. for about 1 hour.
Second heat treatment for -30 minutes, and 220-400 ° C
The third heat treatment is preferably performed stepwise at a high temperature for about 1 to 30 minutes. Also, the self-supporting film may be heated, preferably after peeling from the self-supporting surface,
After drying at about 80 to 250 ° C. under a low tension of not more than g / mm ² to form a solidified film containing the solvent and the produced water in the range of about 5 to 25% by weight, both ends of the film are fixed and heated. Is also good. In the continuous heat treatment at a temperature of 250 ° C. or more, it is preferable that at least both ends of the long film in the direction perpendicular to the longitudinal direction are fixed with a pin tenter, a clip, a frame, or the like. In addition to the heating, the fourth high-temperature heating may be performed at any high temperature in the range of 400 to 550 ° C.

According to the method described above, preferably the thickness is 10
And the surface atomic concentration of Si based on phenyl groups on the film surface is 1% or more, preferably 1 to 20 μm.
%, Tensile modulus of 450 kg / cm ² or more, especially 470
~ 1000 kg / cm ² , linear expansion coefficient 25 × 10 ^-6 c
m / cm / ° C. or less, especially 5 × 10 ^{−6 to} 25 × 10 ⁻⁶ cm
/ Cm / ° C, the water absorption is 1.4% or less, especially 0.5 to 1.
A 3% polyimide film can be produced. The modified polyimide film of the present invention retains the high elasticity inherent to the aromatic polyimide film at a high level, and also has low water absorption by Si bonded to a phenyl group, and also has flexibility, Because it has edge crack resistance and punching properties, a known adhesive such as an epoxy resin or preferably a thermoplastic polyimide,
A heat-resistant thermoplastic adhesive such as a thermoplastic polyamideimide or a copolymer-based polyimide siloxane with an aromatic diamine is provided on at least one surface thereof and laminated with another base material for various uses such as FPC and multilayer wiring boards. , Insulating materials and the like.

[0023]

Embodiments of the present invention will be described below. In each of the following examples, analysis of each component in the polyimide film is performed by, for example, determining the weight ratio of each element on the film surface by using an X-ray photoelectron spectrometer (VG, ESCALAB 200X type)
2x3mm using Mg Ka X-ray source (300W)
Was determined by examining the elements present on the very surface (about several tens of degrees) of the film.

Water absorption measurement: Measured according to ASTM D570-63 (23 ° C. × 24 hours) Tensile modulus measurement: Measured according to ASTM D882-64T Linear expansion coefficient (50-200 ° C.) Measurement: heated at 300 ° C. for 30 minutes Measure the stress-relaxed sample with a TMA device (tensile mode, 2 g load, sample length 10 mm, 20 ° C./min). Elongation measurement: Measure according to ASTM D882-64T. 5% Thermogravimetric loss temperature measurement: TGA device in air 10 ° C /
Heat at a rate of 1 minute and determine the 5% thermal weight loss temperature. In terms of SiO ₂ content of the hydrolysis-polymerization product of the phenyl group-containing alkoxysilane compound (wt%) Measurement: The polyimide film was heated in air up to 800 ° C. to oxidize and decompose polyimide was determined from the residue (SiO ₂₎ .

Reference Example 1 N, N-dimethylacetamide (DMAc) was placed in a polymerization tank.
2470 parts by weight, and then 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) 2
94.22 parts by weight and paraphenylenediamine 108.1
4 parts by weight, and polymerized at 30 ° C. for 10 hours to give a polymer having a logarithmic viscosity (measuring temperature: 30 ° C., concentration: 0.5 g).
/ 100 ml solvent, solvent: N-methyl-2-pyrrolidone) 2.66, and a polyamic acid (imidization ratio: 5% or less) solution having a polymer concentration of 14% by weight was obtained. The rotational viscosity of this polyamic acid solution composition was 3,100 poise.

Reference Example 2 1980 parts by weight of N-methyl-2-pyrrolidone was added to a polymerization tank, and then 147.2 parts by weight of s-BPDA, 100.1 parts by weight of pyromellitic dianhydride, and 75.7 parts of paraphenylenediamine. Parts by weight, 60.6 parts by weight of 4,4'-diaminodiphenyl ether, polymerized at 30 ° C. for 6 hours, and the logarithmic viscosity of the polymer (measuring temperature: 30 ° C., concentration: 0.5 g / 100 ml solvent) , Solvent: N-methyl-2
A solution of polyamic acid (imidation ratio: 5% or less) having a concentration of 2.51 and a polymer concentration of 16.2% by weight was obtained. The rotational viscosity of this polyamic acid solution composition was 2900 poise.

Example 1 To the polyamic acid solution prepared in Reference Example 1, 0.1 part by weight of monostearyl phosphate triethanolamine was added in a ratio of 100 parts by weight of polyamic acid, and the mixture was added at room temperature (about ° C) for 6 hours. The mixture was stirred to obtain a polyamic acid solution composition. To 100 parts by weight of the polyamic acid of this solution composition, 40 parts by weight of diphenyldimethoxysilane and 50 parts by weight of water were added and stirred for 2 hours to prepare a uniform solution. This solution was cast on a glass plate, dried at 120 ° C. for 20 minutes, and then peeled from the glass plate to obtain a self-supporting film.

This self-supporting film is pinched to 4
Fix the sides, heat at 150 ° C for 5 minutes, then 200 ° C
And heated at that temperature for 7 minutes, further heated to 250 ° C., heated at that temperature for 9 minutes, finally raised to 420 ° C., heated at that temperature for 5 minutes, A 75 μm modified polyimide film was produced.

This polyimide film has a phenyl group-containing alkoxysilane compound hydrolyzed / polymerized content of 19.8% by weight calculated from SiO ₂ conversion, a Si atom concentration on the glass surface of the film of 4.5%, The atomic concentration of Si on the air surface is 2.0%, and the tensile modulus is 610 kg / mm.
² , elongation 20%, coefficient of linear expansion 17 × 10 ^-6 cm / c
m / ° C., the water absorption rate was 1.1%, and the 5% thermal weight loss temperature was 590 ° C.

Example 2 A modified polyimide film was obtained in the same manner as in Example 1 except that no water was added. This modified polyimide film had a hydrolysis / polymer content of 16.9 of the phenyl group-containing alkoxysilane compound calculated from SiO ₂ conversion.
2. wt%, the atomic concentration of Si on the glass surface of the film is 3.
1%, Si surface atomic concentration of air surface is 1.5%, tensile modulus is 630 kg / mm ² , elongation is 20%, linear expansion coefficient is 14 × 10 ⁻⁶ cm / cm / ° C., and water absorption is 1.2
%, 5% thermal weight loss temperature was 598 ° C.

Example 3 A modified polyimide film was obtained in the same manner as in Example 1 except that phenyltrimethoxysilane was used instead of diphenyldimethoxysilane. In this modified polyimide film, the content of the hydrolyzed / polymerized phenyl group-containing alkoxysilane compound in terms of SiO ₂ was 23.6% by weight, and the Si concentration on the glass surface of the film was 17.3%.
%, The atomic concentration of Si on the air surface is 3.5%, the tensile modulus is 550 kg / mm ² , the elongation is 18%, and the linear expansion coefficient is 1
8.times.10.sup.- ⁶ cm / cm / .degree. C. and a water absorption of 0.8%,
The 5% thermal weight loss temperature was 600 ° C.

Example 4 A modified polyimide film was obtained in the same manner as in Example 1 except that phenyltrimethoxysilane was used instead of diphenyldimethoxysilane, and water was not added. This modified polyimide film had a phenyl group-containing alkoxysilane compound hydrolysis / polymer content of 16.9% by weight calculated from SiO ₂ ,
The i-surface atomic concentration is 3.1%, the air-surface Si surface atomic concentration is 1.5%, the tensile modulus is 580 kg / mm ² , the elongation is 24%, and the linear expansion coefficient is 10 × 10 ⁻⁶ cm / cm /. ° C, water absorption 1.0%, 5% thermal weight loss temperature 602 ° C
Met.

Example 5 A modified polyimide film was obtained in the same manner as in Example 1 except that the polyamic acid of Reference Example 2 was used. This modified polyimide film has a phenyl group-containing alkoxysilane compound hydrolyzed / polymerized content of 20.4% by weight calculated from SiO ₂ conversion, an Si concentration on the glass surface of the film of 4.6%, and air. 1. The surface Si concentration of the surface is 2.
1%, tensile modulus 480 kg / mm ² , elongation 44
%, The coefficient of linear expansion is 21 × 10 ⁻⁶ cm / cm / ° C.,
The water absorption was 1.4%, and the 5% thermal weight loss temperature was 590 ° C.

Comparative Example 1 A polyimide film was obtained in the same manner as in Example 1 except that diphenyldimethoxysilane and water were not used. This polyimide film has an atomic concentration of Si surface on the glass surface of the film of 0.1% and an atomic concentration of Si surface on the air surface of 0.1%.
%, Tensile modulus 650 kg / mm ² , elongation 24%,
The coefficient of linear expansion was 17 × 10 ⁻⁶ cm / cm / ° C., the water absorption was 1.6%, and the 5% thermal weight loss temperature was 620 ° C. A comparison was made between the polyimide film of Comparative Example 1 and the modified polyimide films of Examples 1 to 5 in terms of flexibility and edge crack resistance, and it was confirmed that there was substantially no difference.

Comparative Example 2 A polyimide film was obtained in the same manner as in Example 1 except that tetramethoxysilane was used instead of diphenyldimethoxysilane. This modified polyimide film is made of SiO
_The content of the hydrolyzed / heat-modified product of tetramethoxysilane in terms of ₂ is 26.2% by weight, the Si surface atomic concentration on the glass surface of the film is 9.9%, the Si surface atomic concentration on the air surface is 4.6%, Tensile modulus of elasticity is 710 kg / mm ² , elongation is 1
4%, coefficient of linear expansion 19 × 10 ⁻⁶ cm / cm / ° C., water absorption 4.5%, 5% thermal weight loss temperature 603 ° C.
Met.

[0036]

Since the present invention is configured as described above, the following effects can be obtained.

The modified polyimide film has a low water absorption, a high elastic modulus, and a high heat resistance.

Claims (4)

[Claims] 1. A film having a surface atomic concentration of Si based on Si bonded to a phenyl group on a film surface of 1% or more, a tensile modulus of 450 kg / mm ² or more, and a linear expansion coefficient of 25 × 10 ⁻⁶ cm / cm. / ° C or less, water absorption is 1.4%
Hereinafter, a modified polyimide film having a 5% thermal weight loss temperature of 500 ° C. or more. 2. The modified polyimide film according to claim 1, wherein Si on the film surface is based on poly (phenyltrialkoxysilane) or poly (diphenyldialkoxysilane). 3. The polyimide constituent unit in the film, wherein the aromatic tetracarboxylic acid component contains 3,3 ′, 4,4′-biphenyltetracarboxylic acid, an acid dianhydride or an acid ester thereof in an amount of 50 mol% or more. The modified polyimide film according to claim 1, wherein the modified polyimide film is derived from an aromatic tetracarboxylic acid component, and the diamine component is derived from a diamine containing at least 30 mol% of paraphenylenediamine. 4. A low-water-absorbing and heat-resistant thermoplastic adhesive such as thermoplastic polyimide, thermoplastic polyamide-imide, or a copolymer-based polyimide siloxane containing an aromatic diamine component is provided on at least one surface of the resin layer so that the resin layer has a low water-absorbing property. The modified polyimide film according to claim 1, wherein