JP2006028216A - Polyimide film and manufacturing method of the polyimide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily slidable polyimide film which contains titanium dioxide particles in the interior of the film and has a surface average particle size and maximum agglomerated particle size of ≤5 μm and a coefficient of static friction of ≤1.4, and a manufacturing method of the polyimide film. <P>SOLUTION: The polyimide film contains the titanium dioxide particles having an average particle size of 0.01-0.80 μm in the entire film, wherein the amount of the titanium dioxide particles contained is 0.010-0.500 wt.% against the weight of the polyimide. The surface average particle size of the polyimide film is ≤5 μm, and the coefficient of static friction between the films is ≤1.80. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a polyimide film containing fine titanium dioxide particles and a method for producing the polyimide film.

  Conventionally, polyimide resins having various excellent properties such as heat resistance and electrical insulation have been widely used in the electronics field. For example, it is used for a flexible printed circuit board, a TAB tape, or a base film for a high density recording medium.

  A polyimide film is generally manufactured by a method of applying a polyamic acid solution on a smooth metal plate, etc., and the film surface is likely to be smooth. Therefore, slipperiness (easiness of slipping) is changed. It was not enough. For this reason, in order to impart high slipperiness, it has been proposed to make an easy-slip film having fine protrusions on the film surface by incorporating inorganic fine particles and the like. As the inorganic fine particles to be contained, fillers having high hardness and high heat resistance such as silica fine particles, silica colloid, calcium hydrogen phosphate, and calcium phosphate are often used. However, when such a filler is used, for example, when silica particles with high hardness are used, when the films come into contact with each other, a polishing action of the film surface by the filler occurs, so that many fine scratches are generated on the film surface. There was a thing.

  For example, Patent Literature 1 describes an aromatic non-thermoplastic polyimide film containing 0.1 to 0.5% by weight of inorganic powder mainly composed of 1 to 5 μm per weight of film resin. . Therefore, in Patent Document 1, it is essential that the particle diameter of the incorporated metal particles is 1 μm or more, and there is a problem that sufficient slipperiness (slidability) is difficult to be expressed unless the particle diameter is 1 μm or more. Has been.

  Further, in Patent Document 2, a part of each inorganic particle having an average particle diameter of 0.01 to 100 μm is retained and buried in the surface layer of the polyimide film. A polyimide film in which a large number of special notes are uniformly formed over the entire surface layer is described, and titanium dioxide is exemplified as the inorganic particles. However, since the film described in Patent Document 2 cannot produce a polyimide film imparted with sufficient slipperiness with inorganic particles embedded in the film, a binder resin (polyamic acid resin solution) containing metal particles can be produced. Has been proposed, but the manufacturing method is difficult, and the cohesive strength of the titanium dioxide particles is strong, which causes a problem of aggregation.

Patent Document 3 discloses a imide film containing particles having a median particle diameter of 0.8 to 1.0 μm as filler particles. However, when filler particles having this particle size are used, it has been difficult to make the maximum diameter of the surface protrusion due to the titanium dioxide particles of the obtained film 5 μm or less.
JP 6-65707 (right of 3) Japanese Patent Laid-Open No. 5-25295 (paragraph numbers 0006 to 0008) JP 2002-256085 (paragraph numbers 0009 to 0010)

  In recent years, with the trend toward lightweight, small, and high-density mounting of electrical and electronic equipment, the metal wiring formed on the surface of flexible printed circuit boards and the like and the interval between wirings have been narrowed, and the demand for lightweight, small, and high-density mounting of metal wiring boards It was necessary to be a thing corresponding to. In recent technology, a fine wiring / wiring interval of 15 μm, which is the sum of the wiring and the wiring interval, is realized.

  In order to realize such a wiring interval, it is desired to control the particle diameter caused by the filler formed on the surface to 5 μm or less. In order to achieve such surface properties, it can be achieved using silica particles, for example, using the method described in Patent Document 2, but scratches occur when the films contact each other as described above. Therefore, a filler having a smaller particle diameter and less scratching on the surface is desired. Titanium dioxide is regarded as a promising filler. However, the titanium dioxide particles have a higher cohesive force than the silica particles, and therefore, the aggregated particles may cause a problem that the surface protrusion diameter becomes large. In addition, if the amount of film particles is decreased in order to suppress aggregation, there is a problem that the slipperiness of the film cannot be imparted.

  In other words, it was very difficult to use titanium dioxide particles to make the maximum diameter of the surface protrusions of titanium dioxide particles 5 μm or less.

This invention can solve the said subject with the following novel polyimide films and its manufacturing method.
1) A polyimide film in which titanium dioxide particles are present in the film, wherein the film surface has protrusions due to titanium dioxide particles, and the maximum diameter of protrusions due to the titanium dioxide particles is 5 μm or less. Polyimide film.
2) The polyimide film according to 1), wherein the coefficient of static friction of the film is 1.80 or less.
3) At least
(A) a step of reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine to obtain a polyamic acid solution (a),
(B) A polyamic acid solution (b) obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine, a titanium dioxide dispersion solution (c) containing at least three components of titanium dioxide particles and an organic solvent for dispersion. Obtaining step,
(C) A step of adding a titanium dioxide dispersion solution (c) to the polyamic acid solution (a) (D) A step of adding an aromatic tetracarboxylic dianhydride or an aromatic diamine after the step (C),
A polyimide film is produced using a titanium dioxide-containing polyamic acid solution (d) produced by a production method comprising: 1) or 2) a method for producing a polyimide film according to 2).
4) The production method according to 3), wherein the titanium oxide particles have an average particle diameter of 0.01 μm or more and 0.80 μm or less.
5) The method for producing a polyimide film according to 3) or 4), wherein the polyamic acid solution (a) has a viscosity of 0.1 to 100 Pa · s.
6) The method for producing a polyimide film according to any one of 3) to 5), wherein the titanium dioxide-containing polyamic acid solution (d) has a viscosity of 100 to 1000 Pa · s.
7) The titanium dioxide dispersion solution (c) has a polyamic acid solid content concentration of 0.5 to 10% by weight and a solid content concentration of titanium dioxide particles of 1 to 20% by weight. 3) The manufacturing method as described.
8) The titanium dioxide-containing polyamic acid solution (d) is added so that the titanium dioxide particles may be 0.010 to 0.500% by weight based on the solid weight of the polyamic acid 3 ) Described production method.
9) The production method according to 3), wherein the end groups of the polyamic acid solution (a) and the end groups of the polyamic acid solution (b) are the same.
10) The production method according to 9), wherein the end groups of the polyamic acid solution (a) and the polyamic acid solution (b) are amine end groups or carboxylic acid end groups.

  According to the present invention, it is a polyimide film in which titanium dioxide particles are present in the film, and the maximum diameter of the surface protrusion by the titanium dioxide particles can be made 5 μm or less. Furthermore, the static friction coefficient between films can be reduced.

  The present invention is described in detail below.

  The present inventors have developed a novel polyimide film in which titanium dioxide particles having a small particle diameter are contained and titanium dioxide particles having a small particle diameter are inherently generated, although titanium dioxide particles having a small particle diameter are used. I found it. That is, a polyimide film in which titanium dioxide particles are present in the film, the surface of the film having protrusions due to titanium dioxide particles, and the maximum diameter of protrusions due to the titanium dioxide particles is 5 μm or less I found.

(Maximum protrusion diameter due to titanium dioxide particles in the polyimide film of the present invention)
In the polyimide film of the present invention, titanium dioxide particles having a small particle diameter are inherent in the film. In this invention, the protrusion diameter by the titanium dioxide particle which exists in the film surface is measured. With respect to the protrusion diameter of titanium dioxide, the range of 200 μm × 200 μm of the film was observed with an optical microscope (manufactured by Nikon Corporation) to observe the maximum protrusion diameter. In the present invention, the maximum particle size is desirably 5 μm or less.

(Average particle diameter of titanium dioxide particles used in the present invention)
The average particle diameter of the titanium dioxide particles is determined by adhering the particles to the surface of the carbon tape, and depositing a conductor such as gold, platinum, carbon, etc. on the inside of the vacuum deposition apparatus (ion sputtering apparatus manufactured by JEOL Ltd.). The particle diameter was directly observed with an electron microscope (manufactured by JEOL Ltd.) and 50 particle diameters were observed, and then the average particle diameter was calculated and taken as the average particle diameter. In particular, most of the titanium dioxide particles have a non-spherical particle shape, and the particle diameter was calculated by the following calculation formula 1.

  The average particle diameter is preferably from 0.01 to 0.80 μm, particularly preferably from 0.02 to 0.70 μm. Moreover, the lubricity (slip property) of a polyimide film can be provided by containing the particle | grains of the said range.

Furthermore, a preferred particle diameter ratio in the present application is calculated by the following calculation formula 2.

  The preferred particle diameter ratio in the present invention is desirably 1.00 to 10.00, and particularly desirably 1.00 to 5.00. That is, it is desirable that the maximum particle length and the shortest particle length are approximately equal. This is desirable because the smaller the particle size ratio, the closer the titanium dioxide particles are to a spherical shape and express easy slipping, and the particle size on the film surface can be reduced.

(Friction coefficient of the polyimide film of the present invention)
The polyimide film of the present invention is a film in which titanium dioxide particles having a small particle diameter are present in the film, so that the static friction coefficient of the polyimide film is small and scratches are unlikely to occur even when the films come into contact with each other.

The static friction coefficient of the polyimide film of the present invention is that the polyimide film is cut out to 10 × 20 cm, the film is fixed on a metal substrate, and the film cut out into a polyimide film 7 × 6 cm is placed on top of it, and the bottom area is A weight of 36 cm 2 and a weight of 860 g was placed on a 7 × 6 cm film, the film was pulled at a speed of 200 mm / min, and the force generated at the moment when the film started moving was defined as a static friction force. The vertical drag is 860 gf from the weight of the weight.
The static friction coefficient is calculated by the following formula.

The static friction coefficient is preferably 1.80 or less.

(Production method of polyimide film)
Below, an example of the manufacturing method of the polyimide film of this invention is shown.
The polyimide film of the present invention can be produced from a polyamic acid solution containing titanium dioxide particles. The titanium dioxide particle-containing polyamic acid solution can be obtained by a production method including at least the following steps (A) to (D).
(A) A step of obtaining a polyamic acid solution (a) by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine (B) A polyamide obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine Obtaining a titanium dioxide dispersion solution (c) comprising at least three components of an acid solution (b), titanium dioxide particles and an organic solvent for dispersion;
(C) Step of adding titanium dioxide dispersion solution (c) to the polyamic acid solution (a) (D) Step of adding aromatic tetracarboxylic dianhydride or aromatic diamine after the step (C) Each step will be described in detail.

Step (A) Step (A) is a step in which an aromatic tetracarboxylic dianhydride and an aromatic diamine are reacted to obtain a polyamic acid solution (a). The aromatic tetracarboxylic dianhydride used in the preparation of the polyamic acid solution (a) of the present invention is a structure containing two dicarboxylic anhydride structures as shown by the following general formula (1). have.

上記一般式（１）中のＲ₁は、少なくとも１つの炭素６員環を含む４価の芳香族残基であることが好ましいが、より好ましい構造としては、下記の一般式群（２）に示す４種類の芳香族残基が挙げられる。

R ₁ in the general formula (1) is preferably a tetravalent aromatic residue containing at least one carbon 6-membered ring, but more preferable structures include those represented by the following general formula group (2). There are four types of aromatic residues shown.

なお、上記一般式群（２）の芳香族残基に含まれる４価の構造上の位置は特に限定されるものではなく、上記各一般式中では、説明の便宜上、価を示す結合線は図示していないが、上記４価のうち、２価ずつが対をなしている構造であることがより好ましい。

In addition, the position on the tetravalent structure included in the aromatic residue of the general formula group (2) is not particularly limited, and in each general formula, for convenience of explanation, Although not shown, it is more preferable to have a structure in which each of the four valences is paired.

R ₂ in the aromatic residue of the general formula group (2) is preferably a divalent organic group selected from the following general formula group (3) containing a benzene ring or a naphthalene ring.

なお、上記一般式群（３）中のＲ₃は、Ｈ−、ＣＨ₃−、Ｃｌ−、Ｂｒ−、Ｆ−、ＣＨ₃０−からなる群より選択される何れか１つの基であればよい。

In the general formula group (3), R ₃ is any one group selected from the group consisting of H—, CH ₃ —, Cl—, Br—, F—, and CH ₃ 0—. Good.

  Specific examples of the aromatic tetracarboxylic dianhydride having the above structure include, for example, p-phenylenebis (trimellitic acid monoester acid anhydride), p-biphenylenebis (trimellitic acid monoester acid anhydride). ), Oxydiphthalic dianhydride, diphenylsulfone-3,4,3 ′, 4′-tetracarboxylic dianhydride, 4,4 ′-(2,2-hexafluoroisopropylidene) diphthalic dianhydride, m -Terphenyl-3,4,3 ', 4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3', 4'-tetracarboxylic dianhydride, cyclobutane-1,2,3 , 4-tetracarboxylic dianhydride, 1-carboxymethyl-2,3,5-cyclopentanetricarboxylic acid-2,6: 3,5-dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4'-biphenyltetra Carboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′benzophenone tetracarboxylic dianhydride, 1,4-bis (3,4 -Dicarboxyphenoxy) benzene dianhydride.

  The aromatic diamine used in the present invention has a structure containing two amino groups as shown in the following general formula (4).

上記一般式（４）中のＲ₄は、少なくとも１つの炭素６員環を含む２価の芳香族残基であることが好ましいが、より好ましい構造としては、下記の一般式群（５）より選択される２価の有機基が挙げられる。

R ₄ in the general formula (4) is preferably a divalent aromatic residue containing at least one carbon 6-membered ring, but a more preferable structure is from the following general formula group (5). The divalent organic group selected is mentioned.

なお、上記一般式群（５）中のＲ₅は、Ｈ−、ＣＨ₃−、Ｃｌ−、Ｂｒ−、Ｆ−、ＣＨ₃０−からなる群より選択される何れか１つの基であればよい。
上記構造を有する芳香族ジアミンの具体的な例としては、例えば、ｏ−、ｍ−またはｐ−フェニレンジアミン、４，４’−ジアミノジフェニルエーテル、３，４’−ジアミノジフェニルエーテル、パラキシレンジアミン、４，４’−ジアミノジフェニルメタン、４，４’−ジアミノジフェニルスルホン、ベンジジン、３，３’−ジメトキシベンジジン、３，３’−ジトリフルオロメチルベンジジン等の芳香族ジアミン、が挙げられる。

In the general formula group (5), R ₅ is any one group selected from the group consisting of H—, CH ₃ —, Cl—, Br—, F—, CH ₃ 0—. Good.
Specific examples of the aromatic diamine having the above structure include, for example, o-, m- or p-phenylenediamine, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, paraxylenediamine, 4, And aromatic diamines such as 4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, benzidine, 3,3′-dimethoxybenzidine, and 3,3′-ditrifluoromethylbenzidine.

  The polyamic acid solution is selected from at least one aromatic tetracarboxylic dianhydride described in the general formula (1) and at least one aromatic diamine described in the general formula (2) in an organic solvent, In order to control the viscosity of the polyamic acid solution (a) to 0.1 to 100 Pa · s, the solid content concentration of the polyamic acid in the organic solvent to be produced is preferably 5 to 40 wt% of the polyamic acid in the organic solvent. Is preferably 10 to 30 wt%, more preferably 13 to 25 wt%, from the viewpoint of handling. Here, the solid content concentration refers to the concentration of the entire nonvolatile component excluding the polymerization solvent contained in the polyamic acid solution, but substantially refers to the concentration of the polyamic acid contained in the polyamic acid solution. become. Therefore, when the total weight of the polyamic acid solution is Ws and the weight of the polyamic acid contained in the polyamic acid solution is Wp, the solid content concentration C is calculated by the following formula (iii).

Solid content concentration C = (Wp / Ws) × 100 (i)
A polyamic acid solution in which the end group obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine with an aromatic tetracarboxylic dianhydride / aromatic diamine ratio of 0.90 or less is an amine end group, or Polyamic acid whose terminal group obtained by reacting aromatic tetracarboxylic dianhydride and aromatic diamine at a ratio of aromatic tetracarboxylic dianhydride / aromatic diamine of 1.10 or more is a carboxylic acid terminal group It is desirable to prepare as a solution. The viscosity of the polyamic acid solution (a) in the present invention is kept for 1 hour in a water bath kept at 23 ° C., and the viscosity at that time is measured with a B-type viscometer. The number of rotations of 7 is measured at 4 rpm, and the viscosity is taken as the viscosity of the polyamic acid solution. In the method of the present invention, the viscosity when adding the titanium dioxide dispersion solution (c) in which titanium dioxide particles are dispersed is desirably 0.1 to 100 Pa · s, and particularly preferably 1.0 to 90 Pa · s. is there. When the viscosity of the polyamic acid solution (a) is high, when the titanium dioxide solution (c) is added, it is desirable that the titanium dioxide particles are easily aggregated and adjusted to 100 Pa · s or less.

  Examples of the organic solvent used for the polymerization of the polyamic acid solution (a) of the present invention include ureas such as tetramethylurea and N, N-dimethylethylurea, dimethyl sulfoxide, diphenylsulfone, and tetramethylsulfone. Sulfoxides or sulfones, such as N, N-methylacetamide (DMAc), N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), γ-butyllactone, hexamethylphosphate triamide Amide or aprotic solvent of phosphorylamide, alkyl halides such as chloroform and methylene chloride, aromatic hydrocarbons such as benzene and toluene, phenols such as phenol and cresol, dimethyl ether, diethyl ether, p- Cresol methyl ether Can ethers and the like, typically may be used in combination as appropriate of two or more as needed using these solvents alone. Of these, amides such as DMF, DMAc and NMP are preferably used.

  This polyamic acid solution (a) can be prepared by carrying out a polymerization reaction in one stage in one reaction apparatus to produce the polyamic acid solution (a). In order to carry out the polymerization reaction in one step, in order to remove insoluble raw materials and mixed foreign substances from the monomer components in the polymerization reaction, the monomer is dissolved in an organic solvent immediately before addition to the reaction vessel and mixed with a filter or the like. If a step of removing is provided, foreign matter and defects in the film can be reduced. Alternatively, it is preferable to carry out the polymerization reaction after reducing the number of foreign matters / defects in the film by directly providing a step of removing powdered foreign matters by directly sieving the powder. The aperture of the filter is preferably 10 μm or less, preferably 5 μm or less, more preferably 3 μm or less. This is because if there are defects on the polyimide film surface due to insoluble raw materials or mixed foreign substances, the adhesion between the film and the metal layer is lowered in the metal layer forming step on the polyimide film.

By the above operation, it is possible to prepare a polyamic acid solution (a) suitable for the present invention. In addition, the polyamic acid solution (a), (B) step (B) step, (B) polyamic acid solution (b) obtained by reacting aromatic tetracarboxylic dianhydride and aromatic diamine and titanium dioxide This is a step of obtaining a titanium dioxide dispersion solution (c) containing at least three components of particles and an organic solvent for dispersion.

  First, the manufacturing method of a polyamic acid solution (b) is demonstrated. The aromatic tetracarboxylic dianhydride and aromatic diamine used as the raw material of the polyamic acid solution (b) are the same as the aromatic tetracarboxylic dianhydride and aromatic diamine exemplified in the polyamic acid solution (a). Are preferably used. The aromatic tetracarboxylic dianhydride and aromatic diamine used in the polyamic acid solution (a) may be the same or different.

  The polyamic acid solution (b) includes at least one aromatic tetracarboxylic dianhydride described in the general formula (1) and at least one aromatic diamine described in the general formula (2) in an organic solvent. It is preferable to produce a polyamic acid solution which is a polyimide precursor by reacting approximately equimolarly. The end group of the solution to be prepared must have the same end group as that of the polyamic acid solution (a). When the end group of the polyamic acid solution (a) is an amine end, the aromatic tetracarboxylic group The ratio of acid dianhydride / aromatic diamine is preferably adjusted to a ratio of 0.8500 to 0.9999. When the ratio is 0.8500 or less, sufficient rigidity is exhibited when formed into a polyimide film called a critical molecular weight. Otherwise, it may be difficult to mold the film. Moreover, when the terminal group of the polyamic acid solution (a) is a carboxylic acid terminal, the aromatic tetracarboxylic dianhydride / aromatic diamine ratio is preferably adjusted at a ratio of 1.0001-1.500, If it is 1.2500 or more, a large amount of excess aromatic tetracarboxylic dianhydride remains in the polyamic acid solution, and excess aromatic tetracarboxylic dianhydride remains in the film body, resulting in various carboxylic acids. appear. For example, when a large amount of carboxylic acid remains in the polyimide film, there is a problem that the hydrolysis rate of the polyimide film is accelerated and the stability of the polyimide film is lowered.

In addition, it is preferable to use the polyimide film whose tensile elasticity modulus of a polyimide film is 4.2 GPa or more and 6.9 GPa or less for selection of the aromatic tetracarboxylic acid or aromatic diamine used suitably for this invention. When the tensile modulus of the polyimide film is within the above range, it is preferable because good irregularities are generated on the surface of the polyimide film obtained from the polyamic acid solution containing fine particles, and the slipperiness is easily exhibited. A person skilled in the art can easily select aromatic tetracarboxylic dianhydrides and aromatic diamine compounds for obtaining a polyimide film having a tensile modulus of elasticity.
As the organic solvent used for the polymerization of the polyamic acid solution (b), the solvents exemplified in the polyamic acid solution (a) are preferably used.

  The solid content concentration of the polyamic acid in the organic solvent to be produced is 5 to 40 wt%, preferably 10 to 30 wt%, more preferably 13 to 25 wt% of the polyamic acid dissolved in the organic solvent from the handling aspect. preferable.

  The average molecular weight of the polyamic acid is preferably 10,000 or more in terms of GPC PEG (polyethylene glycol), so that the titanium dioxide particles can be easily dispersed when preparing the titanium dioxide dispersion.

  The viscosity of the polyamic acid solution was kept in a water bath kept at 23 ° C. for 1 hour, and the viscosity at that time was measured with a B-type viscometer. 7 is measured at 4 rpm and the viscosity is preferably 50 Pa · s or more and 1000 Pa · s, more preferably 100 Pa · s or more and 500 Pa · s, and most preferably 200 Pa · s or more and 350 Pa · s. Is preferable because sufficient dispersibility can be imparted in preparing the titanium dioxide particle solution.

  In addition, about the manufacturing method of a polyamic acid solution (b), the manufacturing method similar to a polyamic acid solution (a) is employable.

  The polyamic acid solution (b) thus obtained, the titanium dioxide particles and the organic solvent for dispersion are added to obtain a titanium dioxide particle dispersion solution (c).

  In the titanium dioxide dispersion (c), a part of the polyamic acid solution of the polyamic acid solution (b) is added to the organic solvent for dispersion, and the solid content concentration of the polyamic acid in the titanium dioxide dispersion (c) is 0.5% by weight or more. Disperse the titanium dioxide particles in the titanium dioxide dispersion so that the solid concentration of the titanium dioxide particles in the titanium dioxide dispersion solution is 1 to 20% by weight. It is preferable to prepare the solution (c).

  The average particle diameter of the titanium dioxide particles used is preferably 0.01 μm or more and 0.80 μm or less.

  The dispersion / mixing of the titanium dioxide particle dispersion solution (c) can be prepared by dispersing the titanium dioxide particle dispersion solution (c) using an apparatus such as a homogenizer that can disperse particles strongly. In the polyamic acid solution (a) and the polyamic acid solution (b), the aromatic tetracarboxylic dianhydride and the aromatic diamine used may be the same or different. However, in the present invention, the end groups of the polyamic acid solution are preferably the same. The terminal group of the polyamic acid solution is a terminal carboxylic acid group when the amount of aromatic tetracarboxylic dianhydride is larger than the amount of aromatic diamine during polymerization. Such a polyamic acid solution is referred to as an acid-terminated polyamic acid solution. Further, when the amount of aromatic diamine is larger than the amount of aromatic tetracarboxylic dianhydride during polymerization, the terminal is an amine group. Such a polyamic acid solution is referred to as an amine-terminated polyamic acid solution. That is, it is preferable that both end groups of the polyamic acid solution (a) and the polyamic acid solution (b) that can be used in the present invention are acid ends or diamine ends. If the end groups are different, the polyamic acid solution may be gelled and cured. Further, for example, the amine terminal can be modified with a dicarboxylic acid anhydride, or the acid terminal can be modified with an amine compound.

  Examples of the organic solvent for dispersion used in the titanium dioxide dispersion solution (c) include ureas such as tetramethylurea and N, N-dimethylethylurea, sulfoxides and sulfones such as dimethylsulfoxide, diphenylsulfone, and tetramethylsulfone, Amides such as N, N-methylacetamide (DMAc), N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), γ-butyllactone, hexamethylphosphoric triamide, or phosphorylamide Aprotic solvents such as alkyl halides such as chloroform and methylene chloride, aromatic hydrocarbons such as benzene and toluene, phenols such as phenol and cresol, ethers such as dimethyl ether, diethyl ether and p-cresol methyl ether S can be mentioned, usually may be used in combination as appropriate of two or more as needed using these solvents alone. Of these, amides such as DMF and DMAc are preferably used.

  As long as the polyamic acid or titanium dioxide particles in the polyamic acid solution are not precipitated even if the solvent used in the polyamic acid solutions (a) and (b) and the solvent of the titanium dioxide dispersion solution are the same type or different types, the type is limited. Not. Similarly, the polyamic acid solution (a) and the polyamic acid solution (b) to be used can be used as long as the polyamic acid composition has the same or different polyamic acid composition as long as the end groups of the polyamic acid solution are the same.

  The amount of the polyamic acid solution (b) added to the titanium dioxide dispersion solution is such that the polyamic acid solid content concentration in the titanium dioxide dispersion solution (c) is finally 0.5 wt% or more and 1.5 wt% or less. The addition is preferable because the dispersion stability of the titanium dioxide particles in the titanium dioxide dispersion solution is improved. When the polyamic acid solid content concentration is 0.5% by weight or less, precipitation of titanium dioxide particles may easily proceed.

  Further, the content of titanium dioxide particles in the titanium dioxide dispersion solution is desirably added so that the solid content concentration is 1 wt% or more and 20 wt% or less. When the solid content concentration of the titanium dioxide particles is more than 20% by weight, the titanium dioxide particles in the titanium dioxide dispersion may tend to aggregate.

  Furthermore, the dispersion apparatus for dispersing the titanium dioxide dispersed by mixing the dispersion solvent, the titanium dioxide particles, and the polyamic acid solution by the above-described addition method may be a known utility apparatus. For example, it can be dispersed using various devices such as a powerful dispersing device such as a homogenizer, or a dispersing device provided with paddle blades.

Step (C) Step (C) is a step in which (C) the titanium dioxide dispersion solution (c) is added to the polyamic acid solution (a).

  The method of adding the titanium dioxide dispersion (c) to the polyamic acid solution (a) is preferably a method of gradually adding the titanium dioxide particle dispersion (c) while stirring and mixing the polyamic acid solution (a). It is desirable to select a stirring apparatus, stirring speed, and stirring temperature for the polyamic acid solution (a) as well as publicly known apparatuses, a stirring speed suitable for the apparatus, and an optimal stirring temperature for the reaction of the polyamic acid solution (a).

  Next, the titanium dioxide particle content of the solution to which the polyamic acid solution (a) and the titanium dioxide dispersion solution (c) are added will be described.

  The content of titanium dioxide particles is that the titanium dioxide particles are contained in a proportion of 0.010 to 0.500% by weight, particularly preferably 0.010 to 0.450% by weight, based on the polyimide resin. It is preferable for imparting the slipperiness of the film. Particularly, it is preferable that the aggregated particles can be reduced by controlling the aggregated particles within the above range.

In addition, content of a titanium dioxide particle can be prescribed | regulated below.
Titanium dioxide content (wt%) =
(Weight of titanium dioxide added to polyamic acid solution) / (polyamic acid weight in polyamic acid solution) / (1- (theoretical water content generated from 1 g of polyamic acid))
When the solid content concentration of titanium dioxide in the polyamic acid solution is 0.5% by weight or more, the particles may aggregate on the surface of the polyimide film. In the case of 0.010% by weight or less, it may be difficult to provide sufficient sliding properties between polyimide films.

  Moreover, when adding the titanium dioxide particle dispersion (c) to the polyamic acid solution (a), it is desirable to use the polyamic acid solution (a) after filtering it at least once with a filter. When the aperture of the filter is 10 μm or less, preferably 5 μm or less, particularly preferably 3 μm or less, the amount of foreign matter in the finally obtained polyamic acid solution is small, and when formed into an imide body such as a polyimide film, This is preferable because the amount of foreign matter is reduced.

(D) Process (D) A process is a process of adding aromatic tetracarboxylic dianhydride or aromatic diamine after the (C) process.

  After the titanium dioxide dispersion (c) is added to the polyamic acid solution (a), the polyamic acid solution is stirred and mixed for at least 1 minute to 5 hours, preferably 10 minutes to 3 hours, and then the polyamic acid. When (a) is an amine end group solution, an aromatic tetracarboxylic dianhydride is added to increase the viscosity. When the polyamic acid (a) is a carboxylic acid end group, an aromatic diamine is added. It is preferable to increase the viscosity by additional addition to obtain a polyamic acid solution having a desired viscosity. In addition, the form at the time of addition of aromatic tetracarboxylic dianhydride and aromatic diamine may be a solution, or may be in the form of a powder or a slurry solution dispersed in a solvent.

  The viscosity of the finally obtained polyamic acid solution (d) was measured with a 23 ° C. varnish using a B-type viscometer (rotor No. 7 with a rotation speed of 4 rpm) in view of moldability to a polyimide film. The viscosity is preferably 100 Pa · s or more and 1000 Pa · s, more preferably 100 Pa · s or more and 500 Pa · s, and most preferably 200 Pa · s or more and 350 Pa · s. Most preferred above.

  In addition, an antioxidant, a light stabilizer, a flame retardant, an antistatic agent, a heat stabilizer, an ultraviolet absorber, or various reinforcing agents may be added to the polyamic acid organic solvent solution (d) as necessary. Also good.

  During the polymerization reaction of the polyamic acid, if the polymerization temperature is high, the decomposition reaction of the polyamic acid solution is likely to proceed, and there is a problem that the polymerization reaction of the polyamic acid solution does not proceed. Therefore, the liquid temperature of the reaction solution is preferably 60 ° C. or lower, and more preferably 50 ° C. or lower.

  Furthermore, the polyamic acid contained in the polyamic acid solution according to the present invention may be two or more types. That is, the polyamic acid solution (a) produced by the production method according to the present invention contains two or more polyamic acids by adding and mixing one or more polyamic acid solutions produced by other polymerization reactions. A polyamic acid solution may be used. Moreover, various conditions in the polyamic acid polymerization step may be changed to carry out the production method according to the present invention, and the obtained polyamic acid solutions having different average molecular weights may be mixed.

  However, when mixing the plurality of types of polyamic acid solutions, it is preferable that the types of end groups of the polyamic acid are the same. Specifically, the terminal group of the polyamic acid may be a carboxylic acid group (hereinafter referred to as an acid terminal) or an amine group (hereinafter referred to as an amine terminal). The polyamic acids at the terminals or the polyamic acids at the amine terminals are mixed, and the acid-terminated polyamic acid and the amine-terminated polyamic acid cannot be mixed.

(Manufacture of polyimide film)
In order to obtain the polyimide film of the present invention from the thus-obtained titanium dioxide particle-containing polyamic acid solution (d), either a thermal method of thermally dehydrating and ring-closing or a chemical method using a dehydrating agent may be used. However, the chemical method is preferable because the polyimide film produced has excellent mechanical properties such as elongation and tensile strength. Further, the chemical method has advantages such as imidization in a short time. A thermal method and a chemical method can be used in combination.

  As a typical method for producing a polyimide film from a polyamic acid organic solvent solution, a mixed solution obtained by adding a stoichiometric or higher amount of a dehydrating agent and a catalyst to the above polyamic acid organic solvent solution is used to form a drum or endless belt from a slitted die. The film is cast on a support such as a film and formed into a film. The gel film is self-supporting by heating and drying on the support at 200 degrees or less for 1 to 20 minutes, and then the film is drawn from the support. Remove. Next, both ends of the film are fixed. A chemical ring closure method in which imidization proceeds by gradually or stepwise heating from 100 degrees to 600 degrees, and after slow cooling, end fixing is removed to obtain a polyimide film. And an organic solvent solution of polyamic acid not containing a dehydrating agent and a catalyst is cast-coated on a support such as a drum or an endless belt from a slit base and formed into a film. After making into a gel film having self-supporting property by heating and drying in minutes, the film is peeled off from the support. Next, both ends of the film are fixed. Thereafter, there is a thermal ring closure method in which imidization proceeds by gradually or stepwise heating from 100 degrees to 600 degrees, and after the slow cooling, fixing of the end portion is removed to obtain a polyimide film. These chemical ring closure methods and thermal ring closure methods can be used in combination.

  Examples of the dehydrating agent used in the chemical ring closure method include aliphatic acid anhydrides such as acetic anhydride and aromatic acid anhydrides. Examples of the catalyst include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as pyridine and isoquinoline.

  Before mixing the dehydrating agent and the catalyst with the polyamic acid organic solvent solution, a step of removing undissolved raw materials and mixed foreign matters with a filter or the like is provided to reduce foreign matters and defects in the film. The aperture of the filter is preferably 1/2, preferably 1/5, and more preferably 1/10 of the thickness of the obtained film.

  Although the content of the dehydrating agent and the catalyst with respect to the polyamic acid depends on the structural formula constituting the polyamic acid, the number of dehydrating agent moles / the number of amide group moles in the polyamic acid is preferably 10 to 0.01, and in the catalyst / polyamic acid The number of moles of amide group is preferably 10 to 0.01. More preferably, the number of moles of dehydrating agent / the number of amide groups in the polyamic acid is preferably 5 to 0.5, and the number of moles of amide groups in the catalyst / polyamic acid is preferably 5 to 0.5. In this case, a reaction retarder such as acetylacetone may be used in combination. The contents of the dehydrating agent and the catalyst with respect to the polyamic acid may be defined by the time (pot life) from when the polyamic acid and the dehydrating agent / catalyst mixture are mixed at 0 ° C. until the viscosity starts to increase. Generally, the pot life is preferably 0.1 minutes to 60 minutes, more preferably 0.5 minutes to 20 minutes.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples. In particular, the present invention describes an example of a method for producing a polyimide film.

Example 1
(Preparation of polyamic acid solution (b))
DMF (N, N-dimethylformamide) is taken into a separable flask, 5.0 equivalents of p-PDA (paraphenylenediamine) and 7.0 equivalents of ODA (4,4′-diaminodiphenyl ether) are taken into p-PDA, Stir well at room temperature until ODA is completely dissolved. Next, TMHQ (p-phenylenebis (trimellitic acid monoester anhydride)) 8.0 equivalents and PMDA (pyromellitic dianhydride) 3.9 equivalents were gradually added, and then stirred for 40 minutes. A polyamic acid solution having a solid content concentration of 15% by weight, a viscosity of 160 Pa · s (23 ° C.), and a terminal group of a carboxylic acid terminal group was obtained.
(Preparation of titanium dioxide dispersion)
DMF was added into a glass beaker having a capacity of 100 ml, and the polyamic acid solution (b) was mixed so that the solid content concentration of the polyamic acid in the titanium dioxide dispersion solution was 1.0 wt%. , Titanium dioxide particles, ST-01 (titanium dioxide average particle diameter 0.11 μm, manufactured by Ishihara Sangyo Co., Ltd.) were mixed so that the solid content concentration was 10% by weight, stirred for 10 minutes with a homogenizer, and then dispersed in titanium dioxide. Used as. The average particle diameter of the titanium dioxide particles is determined by adhering the particles to the surface of the carbon tape, and then depositing a conductor such as gold, platinum, carbon, etc. in a vacuum deposition apparatus (ion sputtering apparatus manufactured by JEOL Ltd.). Then, the particle diameter was directly observed with an electron microscope (manufactured by JEOL Ltd.), and 50 particle diameters were observed. Then, the average particle diameter was calculated and used as the average particle diameter. In particular, most of the titanium dioxide particles have a non-spherical particle shape, and the particle diameter was calculated by the following calculation formula 1.

Furthermore, the particle size ratio is calculated from the following calculation formula 2.

(Preparation of polyamic acid solution (a))
DMF (N, N-dimethylformamide) is taken into a separable flask, 5.0 equivalents of p-PDA (paraphenylenediamine) and 7.0 equivalents of ODA (4,4′-diaminodiphenyl ether) are taken into p-PDA, Stir well at room temperature until ODA is completely dissolved. Next, 8.0 equivalents of TMHQ (p-phenylenebis (trimellitic acid monoester anhydride)) and 2.8 equivalents of PMDA (pyromellitic dianhydride) are gradually added, and then stirred for 40 minutes. A polyamic acid solution having a solid concentration of 15% by weight and a viscosity of 50 Pa · s (23 ° C.) was obtained. The adjusted titanium dioxide dispersion solution is added to the polyamic acid solution so that the solid content concentration of the titanium dioxide particles with respect to the polyamic acid is 0.15% by weight, and further 1.2 equivalents of PMDA is added to increase the viscosity. At 200 Pa · s (23 ° C.), a polyamic acid solution in which the terminal group was a carboxylic acid terminal group was obtained. The solid content concentration of the polyamic acid solution was 15% by weight.
(Production method of polyimide film)
100 g of the above polyamic acid solution is mixed with 20 g of acetic anhydride (AA) and 5 g of isoquinoline (IQ), and the mixture is cast on an aluminum plate and dried at 100 ° C. for 3 minutes. Peel from the aluminum plate, fix the coating on the support frame, and then heat at 100 ° C for 2 minutes, 350 ° C for 20 seconds, 450 ° C for 20 seconds, and further at 500 ° C for 20 seconds, dehydrating and ring-closing drying As a result, a polyimide film having a thickness of 25 μm was obtained.

The static friction coefficient of the polyimide film obtained by the above method and the maximum protrusion diameter of the titanium dioxide particles on the film surface were measured as follows.
(Static friction coefficient)
The polyimide film is cut out to 10 × 20 cm, the film is fixed on a metal substrate, and the film cut into polyimide film 7 × 6 cm is placed on top of it, and the weight of the bottom area is 36 cm 2 and the weight is 860 g. The film was pulled on a 7 × 6 cm film and pulled at a speed of 200 mm / min, and the force generated at the moment when the film started moving was defined as the static friction force. The vertical drag is 860 gf from the weight of the weight.

The static friction coefficient was calculated by the following formula.

(Measurement of maximum protrusion diameter by titanium dioxide particles in polyimide film of the present invention)
In the polyimide film of the present invention, titanium dioxide particles having a small particle diameter are inherent in the film. In this invention, the protrusion diameter by the titanium dioxide particle which exists in the film surface is measured. With respect to the protrusion diameter of titanium dioxide, the range of 200 μm × 200 μm of the film was observed with an optical microscope (manufactured by Nikon Corporation) to observe the maximum protrusion diameter.

(Example 2)
As titanium dioxide particles, a film was produced using the same film preparation method as in Example 1, except that SA-1 (manufactured by Sakai Chemical Co., Ltd., titanium dioxide average particle size 0.26 μm) was used. Then, the physical property values were evaluated. The evaluation results are shown in Table 1.

Example 3
As titanium dioxide particles, a film was prepared using the same film preparation method as in Example 1 except that titanium dioxide particles of KRONOS KA-30 (manufactured by Titanium Industry Co., Ltd., average particle diameter 0.24 μm) were used. The physical property values were evaluated. The evaluation results are shown in Table 1.

(Examples 4 to 6)
As titanium dioxide particles, TA-200 (manufactured by Fuji Titanium Co., Ltd., average particle size 0.30 μm) titanium dioxide particles were used, and the same method for preparing a film as in Example 1 except that the addition amount shown in Table 1 was added. A film was prepared using and the physical property values were evaluated. The evaluation results are shown in Table 1.

(Example 7)
A film was prepared using the same method for preparing a film as in Example 1 except that T805 (manufactured by Nippon Aerosil Co., Ltd., average particle size: 0.02 μm) was used as the titanium dioxide particles. Evaluation was performed. The evaluation results are shown in Table 1.

(Example 8)
(Preparation of polyamic acid solution (b))
DMF (N, N-dimethylformamide) was taken into a separable flask, 10.0 equivalents of ODA (4,4′-diaminodiphenyl ether) was taken, and stirred well at room temperature until ODA was completely dissolved. Next, 10.0 equivalents of PMDA (pyromellitic dianhydride) is gradually added, and then stirred for 40 minutes. The polyamic acid solution has a solid content concentration of 15% by weight and a viscosity of 200 Pa · s (23 ° C.). Got.
(Preparation of titanium dioxide dispersion)
In a 100 ml glass beaker, DMF was added, and the polyamic acid solution (b) was mixed so that the solid content concentration of the polyamic acid solution of the titanium dioxide dispersion was 1.0 wt%. In addition, titanium dioxide particles, ST-01 (average particle size 0.11 μm, manufactured by Ishihara Sangyo Co., Ltd.) were mixed so that the solid concentration was 10% by weight, stirred for 10 minutes with a homogenizer, and then used as a titanium dioxide dispersion solution. Using.
(Preparation of polyamic acid solution (a))
DMF (N, N-dimethylformamide) is taken into a separable flask, 5.0 equivalents of p-PDA (paraphenylenediamine) and 7.0 equivalents of ODA (4,4′-diaminodiphenyl ether) are taken into p-PDA, Stir well at room temperature until ODA is completely dissolved. Next, 8.0 equivalents of TMHQ (p-phenylenebis (trimellitic acid monoester anhydride)) and 2.8 equivalents of PMDA (pyromellitic dianhydride) are gradually added, and then stirred for 40 minutes. A polyamic acid solution having a solid concentration of 15% by weight and a viscosity of 50 Pa · s (23 ° C.) was obtained. The adjusted titanium dioxide dispersion solution is added to the polyamic acid solution so that the solid content concentration of the titanium dioxide particles with respect to the polyamic acid is 0.15 wt%, and PMDA 1.22 equivalent is further added to increase the viscosity. A polyamic acid solution of 210 Pa · s (23 ° C.) was prepared. The solid content concentration of the polyamic acid solution was 15% by weight.
(Production method of polyimide film)
100 g of the above polyamic acid solution is mixed with 20 g of acetic anhydride (AA) and 5 g of isoquinoline (IQ), and the mixture is cast on an aluminum plate and dried at 100 ° C. for 5 minutes. Peel from the aluminum plate, fix the coating on the support frame, and then heat at 100 ° C for 2 minutes, 350 ° C for 20 seconds, 450 ° C for 20 seconds, and further at 500 ° C for 20 seconds, dehydrating and ring-closing drying As a result, a polyimide film having a thickness of 25 μm was obtained.

  The physical properties of the polyimide film were evaluated under the same conditions as in Example 1. The evaluation results are shown in Table 1. It has been clarified that even if the compositions of the polyamic acid solution (a) and the polyamic acid solution (b) are different, there is no great difference in the property values of the polyimide film.

(Comparative Example 1)
A film similar to that of Example 1 except that the amount of TA-200 used in Examples 4 to 6 (produced by Fuji Titanium Co., Ltd., average particle size 0.30 μm) was changed to 0.005% by weight. Films were prepared using the preparation method, and physical properties were evaluated. The evaluation results are shown in Table 1.

  (Comparative Example 2) A film containing no titanium dioxide particles was produced under the conditions of Example 1 and the coefficient of static friction was measured. As a result, it became clear that the static friction coefficient of the film was a big problem.

Observation part of particle diameter of polyimide film surface of this application

Claims (10)

It is a polyimide film in which titanium dioxide particles are present in the film, and there are protrusions due to titanium dioxide particles on the surface of the film, and the maximum diameter of protrusions due to the titanium dioxide particles is 5 μm or less. Polyimide film. The polyimide film according to claim 1, wherein the static friction coefficient of the film is 1.80 or less. at least,
(A) a step of reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine to obtain a polyamic acid solution (a),
(B) A polyamic acid solution (b) obtained by reacting an aromatic tetracarboxylic dianhydride and an aromatic diamine, a titanium dioxide dispersion solution (c) containing at least three components of titanium dioxide particles and an organic solvent for dispersion. Obtaining step,
(C) A step of adding a titanium dioxide dispersion solution (c) to the polyamic acid solution (a) (D) A step of adding an aromatic tetracarboxylic dianhydride or an aromatic diamine after the step (C),
A polyimide film is manufactured using the titanium dioxide containing polyamic-acid solution (d) manufactured by the manufacturing method containing this, The manufacturing method of the polyimide film of Claim 1 or 2 characterized by the above-mentioned. The manufacturing method according to claim 3, wherein the titanium oxide particles have an average particle size of 0.01 μm to 0.80 μm. The method for producing a polyimide film according to claim 3 or 4, wherein the polyamic acid solution (a) has a viscosity of 0.1 to 100 Pa · s. The method for producing a polyimide film according to any one of claims 3 to 5, wherein the titanium dioxide-containing polyamic acid solution (d) has a viscosity of 100 to 1000 Pa · s. The titanium dioxide dispersion solution (c) has a polyamic acid solid content concentration of 0.5 to 10% by weight and a solid content concentration of titanium dioxide particles of 1 to 20% by weight. 3. The production method according to 3. 4. The titanium dioxide-containing polyamic acid solution (d) is added so that titanium dioxide particles are 0.010 to 0.500% by weight based on the solid weight of the polyamic acid. The manufacturing method as described. The production method according to claim 3, wherein the end groups of the polyamic acid solution (a) and the end groups of the polyamic acid solution (b) are the same. The production method according to claim 9, wherein the end groups of the polyamic acid solution (a) and the polyamic acid solution (b) are amine end groups or carboxylic acid end groups.

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