JP2013018818A - Polyimide composition for surface modification and surface modifying method of machine member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyimide composition for surface modification capable of forming at low temperature, a polyimide film that can express abrasion resistance and slidability in addition to properties such as strength and heat resistance which polyimide originally has.SOLUTION: The polyimide composition for surface modification includes: a polyimide solution (A) obtained by mixing a polyamide acid having a structure shown by Formula (I), a dehydration-cyclization reagent, and a solvent; and a fluorine-based resin (B). In the formula (I), X denotes a divalent organic group which may be substituted by a halogen atom; Y denotes a divalent organic group; and Z, Zand Zeach independently denote a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

Description

  The present invention provides wear resistance to mechanical members such as fixing rolls or belts for copying machines, bearings, O-rings, gears, guides, rollers, liners, pulleys, star wheels, slide plates, pallets, and screws. The present invention relates to a polyimide composition for surface modification for imparting slidability, heat resistance, and the like, and a surface modification method for a machine member using the same.

  Polyimide is obtained by imidizing a polyamic acid synthesized using an acid dianhydride and a diamine compound as a reaction raw material, and is derived from the imide ring and can exhibit high strength and excellent heat resistance. . Therefore, conventionally, a film made of polyimide is formed on the surface of various mechanical members to improve the performance.

  For example, a member such as a roll or belt for fixing or transferring in an image forming and recording apparatus such as a copier, a facsimile machine, a printer, or a complex machine thereof (collectively referred to as “copier” in the present specification). Will be exposed to pressurized and / or heated conditions. Therefore, in order to improve physical properties such as heat resistance and strength, a polyimide film is coated on the surface. As a polyimide used for such a copying machine member, for example, a polyimide obtained by using one or more acid dianhydrides and two or more diamine compounds, and at least one of the acid dianhydrides and diamine compounds. The seed compound has an ether bond and / or a thioether bond in the molecule, and the total of ether bonds and thioether bonds in the polymerization repeating unit derived from the acid dianhydride and diamine compound constituting the polyimide is 2 or more. A polyimide has been proposed (Patent Document 1). Such a polyimide has a specified structure so as to exhibit an effect excellent in water repellency in addition to strength and heat resistance.

International Publication No. 2010/150908 Pamphlet

  As described above, the polyimide described in Patent Document 1 was intended to improve water repellency as well as excellent strength and heat resistance for a copying machine member, but the surface of the copying machine member is always severely rubbed. Therefore, high wear resistance is required from the viewpoint of the member life. Abrasion resistance is also an important characteristic in other mechanical parts such as bearings, O-rings, gears, guides, rollers, liners, pulleys, star wheels, slide plates, pallets, screws, etc. There is a high demand for improved wear resistance. Further, in the above-described mechanical member, slidability is also an essential characteristic, and improvement thereof is expected. From the above, there has been a demand for a surface modifying material for a mechanical member that can improve the wear resistance and slidability in addition to the properties inherent to polyimide such as strength and heat resistance.

  In addition, as is the case with the polyimide described in Patent Document 1, polyimide is generally produced by applying a polyamic acid solution as a precursor on a base material (mechanical member) and then imidizing with heat by firing. Be filmed. This is because when polyimide is formed, it is difficult to melt and also dissolve in a solvent, so that it is difficult to apply it onto a substrate and form it into a film. However, when a polyimide film is formed in this way, it is generally necessary to perform baking at a high temperature of 300 ° C. or higher in order to promote imidization and to fully exhibit the inherent properties such as strength and heat resistance. . For example, it is conceivable to perform imidization at a relatively low temperature over time, but in this case, it becomes easy to lower the molecular weight of the polyamic acid once the imidization proceeds, so that only a polyimide having a lower molecular weight is generated. Thus, there arises a problem that the strength or the like of the obtained polyimide film is lowered. Therefore, when baking after apply | coating a polyamic-acid solution on a base material, there existed a restriction | limiting that the material which can endure the high temperature at the time of baking as much as that of a base material had to be selected. Therefore, a technique that can be formed at a relatively low temperature that can remove the solvent in the polyimide film has also been demanded.

  The present invention has been made in view of the above circumstances, and its purpose is to provide a polyimide film that can also exhibit wear resistance and slidability in addition to the properties inherent to polyimide such as strength and heat resistance. An object of the present invention is to provide a surface-modifying polyimide composition that can be formed at a low temperature, and a surface-modifying method for a mechanical member using the surface-modifying polyimide composition.

  As a result of intensive studies to solve the above problems, the inventors of the present invention can mix a polyamic acid having a specific structure with a dehydrating cyclization reagent and a solvent to chemically imidize without heating. The resulting polyimide can be obtained in the form of a solution dissolved in a solvent, and the polyimide solution thus obtained has a good dispersibility and solubility due to the specific structure of the polyamic acid used as a raw material. If it is a composition containing such a polyimide solution and a fluororesin, it can be heated at a low temperature so that the solvent can be removed without lowering the molecular weight after coating on the substrate. By drying, in addition to the inherent properties of polyimide such as strength and heat resistance, it is possible to easily form a film with excellent wear resistance and slidability. However, the present invention has been completed.

  That is, the polyimide composition for surface modification of the present invention comprises a polyimide solution (A) obtained by mixing a polyamic acid having a structure represented by the following formula (I), a dehydrating cyclization reagent, and a solvent; A fluorine resin (B) is included.

［上記式（Ｉ）中、Ｘはハロゲン原子で置換されていてもよい２価の有機基を示し；Ｙは２価の有機基を示し；Ｚ^１、Ｚ^２およびＺ^３は互いに独立して水素原子、フッ素原子、塩素原子、臭素原子またはヨウ素原子のいずれかを示す。該式（Ｉ）で表される構造の中には、１個以上の炭素原子−ハロゲン原子結合が含まれることが好ましく、式（Ｉ）中のＸは、具体的には、ジ−トリフルオロメチル−メチレン基（−Ｃ（ＣＦ_３）_２−）、ｐ−ジオキシ−フェニレン基（−Ｏ−Ｃ_６Ｈ_４−Ｏ−）、ｐ−ジオキシ−テトラフルオロフェニレン基（−Ｏ−Ｃ_６Ｆ_４−Ｏ−）からなる群より選ばれる１種であることが好ましい。］

[In the above formula (I), X represents a divalent organic group which may be substituted with a halogen atom; Y represents a divalent organic group; Z ¹ , Z ² and Z ³ are independently of each other. One of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom is shown. The structure represented by the formula (I) preferably contains one or more carbon atom-halogen atom bond, and X in the formula (I) is specifically di-trifluoro Methyl-methylene group (—C (CF ₃ ) ₂ —), p-dioxy-phenylene group (—O—C ₆ H ₄ —O—), p-dioxy-tetrafluorophenylene group (—O—C ₆ F ₄₎ -O-) is preferably one selected from the group consisting of: ]

  In the polyimide composition for surface modification of the present invention, the dehydration cyclization reagent is preferably a tertiary amine or a combination of a tertiary amine and a carboxylic acid anhydride, and the solvent is N, N- It is preferably at least one selected from the group consisting of dimethylacetamide, N, N-dimethylformamide and N-methylpyrrolidone. Moreover, in the polyimide composition for surface modification of this invention, it is preferable that content of the said fluororesin (B) is 25 mass parts or more with respect to 100 mass parts of polyimides in a polyimide solution (A). Furthermore, the polyimide composition for surface modification of the present invention preferably contains carbon black.

  The surface modification method for a mechanical member of the present invention is characterized in that the surface-modifying polyimide composition of the present invention described above is applied to the surface of the mechanical member, and the solvent is removed at a temperature of 250 ° C. or lower.

  According to the present invention, for example, in a machine member such as a fixing or transfer roll or belt of a copying machine, a bearing, an O-ring, a gear, a guide, a roller, a liner, a pulley, a star wheel, a slide plate, a pallet, or a screw. Since a film made of polyimide obtained by imidizing a polyamic acid having a specific structure can be formed, strength, heat resistance, wear resistance and the like can be imparted to the surfaces of various mechanical members. Further, the composition of the present invention for forming a film made of the above polyimide contains a fluororesin with good dispersibility and solubility because of the specific structure of the polyamic acid which is a polyimide raw material. Exhibits excellent slidability. Furthermore, since the polyimide solution contained in the composition of the present invention used for forming the polyimide film is a solution in which the polyamic acid is mixed with a dehydrating cyclization reagent and a solvent and chemically imidized, the solvent The film can be formed at a low temperature that can remove the film, and the material of the mechanical member (base material) is not limited, and can be applied to a wide range of existing mechanical members.

  The surface-modifying polyimide composition of the present invention (hereinafter simply referred to as “polyimide composition”) contains a predetermined polyimide solution (A) and a fluororesin (B) as essential components. This makes it possible to form a film having excellent strength and heat resistance as well as wear resistance and slidability at a low temperature. Below, the preparation method of a polyimide solution (A) is demonstrated first.

  The polyimide solution (A) is obtained by mixing a polyamic acid having a structure represented by the following formula (I), a dehydrating cyclization reagent, and a solvent.

［上記式（Ｉ）中、Ｘはハロゲン原子で置換されていてもよい２価の有機基を示し；Ｙは２価の有機基を示し；Ｚ^１、Ｚ^２およびＺ^３は互いに独立して水素原子、フッ素原子、塩素原子、臭素原子またはヨウ素原子のいずれかを示す。］
前記ポリアミド酸がかかる特定の構造単位を有することにより、形成されるポリイミド膜の耐摩耗性が向上するとともに、摺動性の向上に寄与する後述のフッ素系樹脂（Ｂ）の分散性や溶解性を良好に保つことが可能になる。

[In the above formula (I), X represents a divalent organic group which may be substituted with a halogen atom; Y represents a divalent organic group; Z ¹ , Z ² and Z ³ are independently of each other. One of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom is shown. ]
When the polyamic acid has such a specific structural unit, the wear resistance of the formed polyimide film is improved, and the dispersibility and solubility of the fluororesin (B), which will be described later, contribute to the improvement of the slidability. Can be kept in good condition.

In the above formula (I), examples of the divalent organic group which may be substituted with the halogen atom represented by X include, for example, —C (CF ₃ ) ₂ —, —C (CF ₃ ) ₂ —C (CF _{3) 2} - or fluorine atom-containing alkylene group; p- dioxy - phenylene group; fluorine-containing p- dioxy - phenylene group (wherein fluorine atom is only to be substituted with at least one of the hydrogen atoms of the phenylene group ); Etc. are preferred. More specifically, X represents a di-trifluoromethyl-methylene group (—C (CF ₃ ) ₂ —), a p-dioxy-phenylene group (—O—C ₆ H ₄ —O—), p-dioxy. - is preferably one selected from the group consisting of tetrafluoroethylene-phenylene group _{(-O-C 6 F 4 -O-} ).
The structure represented by the above formula (I) preferably contains one or more carbon atom-halogen atom bonds. Here, the halogen atom in the carbon atom-halogen atom bond may be introduced as X or may be introduced as Z ^{1 to} Z ³ .

  In the above formula (I), the divalent organic group represented by Y is not particularly limited, and examples thereof include a divalent organic group having an aromatic ring. Specifically, a group composed of one benzene ring or a group having a structure in which two or more benzene rings are bonded via a carbon atom, an oxygen atom, a sulfur atom or directly. Specifically, the following groups can be exemplified.

  The divalent organic group having an aromatic ring described above as an example of Y is a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, preferably a fluorine atom or a chlorine atom, if it can be substituted). , More preferably a fluorine atom), and may be substituted with a group selected from the group consisting of a methyl group and a trifluoromethyl group. There may be a plurality of these substituents, in which case the types of the substituents may be the same or different. A preferable substituent substituted with a divalent organic group having an aromatic ring is a fluorine atom and / or a trifluoromethyl group, and most preferably a fluorine atom. In the group which is an example of Y, the larger the number of fluorine atoms contained, the more the fluororesin can be contained with better dispersibility or solubility when the fluororesin described later is contained in the polyimide solution. Therefore, it is preferable.

In the above formula (I), Z ¹ , Z ² and Z ³ may be the same or different and are each independently selected from a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. It is. When the fluororesin described later is contained in the polyimide solution, preferably at least one of Z ¹ , Z ^2, and Z ³ from the viewpoint that the fluororesin can be contained with good dispersibility or solubility. One is preferably a fluorine atom, and more preferably all of Z ¹ , Z ² and Z ³ are fluorine atoms. Of course, all of Z ¹ , Z ² and Z ³ may be hydrogen atoms.

  The polyamic acid can be produced by subjecting an acid dianhydride and a diamine compound to an amidation reaction in a solvent by a known method. Here, the acid dianhydride and diamine compound used as raw materials may be appropriately selected according to the structure of the polyamic acid to be obtained. The amidation reaction proceeds, for example, by stirring at room temperature in an inert gas atmosphere such as nitrogen to obtain a uniform solution. The solvent may be appropriately selected according to the acid dianhydride and diamine compound used as raw materials. Here, when a solvent described later mixed with polyamic acid is used when preparing a polyimide solution, an amide is used. Since the reaction liquid obtained by the conversion reaction can be used as it is as a mixture of polyamic acid and a solvent (polyamic acid solution (A)), it is preferable.

  The dehydrating cyclization reagent can be used without particular limitation as long as it has the action of chemically dehydrating and cyclizing polyamic acid to form a polyimide. As such a dehydrating cyclization reagent, it is preferable that a tertiary amine is used alone or a combination of a tertiary amine and a carboxylic acid anhydride is used because imidization can be promoted efficiently.

  Examples of the tertiary amine include trimethylamine, triethylamine, tripropylamine, tributylamine, pyridine, 1,4-diazabicyclo [2.2.2] octane (DABCO), 1,8-diazabicyclo [5.4.0]. Undec-7-ene, 1,5-diazabicyclo [4.3.0] non-5-ene, N, N, N ′, N′-tetramethyldiaminomethane, N, N, N ′, N′-tetra Methylethylenediamine, N, N, N ′, N′-tetramethyl-1,3-propanediamine, N, N, N ′, N′-tetramethyl-1,4-phenylenediamine, N, N, N ′, N′-tetramethyl-1,6-hexanediamine, N, N, N ′, N′-tetraethylmethylenediamine, N, N, N ′, N′-tetraethylethylenediamine and the like can be mentioned. It is. Among these, pyridine, DABCO, N, N, N ′, N′-tetramethyldiaminomethane are particularly preferable, and DABCO is more preferable. Only one type of tertiary amine may be used, or two or more types may be used.

  Examples of the carboxylic acid anhydride include acetic anhydride, trifluoroacetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, succinic anhydride, maleic anhydride, and the like. Among these, acetic anhydride and trifluoroacetic anhydride are particularly preferable, and acetic anhydride is more preferable. Only one type of carboxylic anhydride may be used, or two or more types may be used.

  As the solvent, a polar solvent having excellent solubility is suitable. Examples include N, N-dimethylacetamide, N, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide and the like, among which N, N-dimethylacetamide, N, N-dimethylformamide and N-methyl are particularly mentioned. One or more selected from the group consisting of pyrrolidone is preferable in terms of easy solvent removal during film formation.

  In preparing the polyimide solution, the above-described polyamic acid (polyamic acid solution (A)), a dehydrating cyclization reagent, and a solvent may be mixed, and imidization proceeds by mixing, and the resulting mixture becomes a polyimide solution. Become.

  The mixing amount of the polyamic acid may be a concentration such that polyimide does not precipitate at room temperature when the polyimide solution is used. From this viewpoint, the mixing amount of the polyamic acid is preferably 40% by mass or less, more preferably 35% as the polyamic acid concentration with respect to the total mass of the polyamic acid (polyamic acid solution (A)), the dehydrating cyclization reagent and the solvent. It is below mass%. The lower limit of the concentration of the polyamic acid is not particularly limited, and is preferably 5% by mass or more, and more preferably 10% by mass or more. In any case, the specific concentration may be determined by preliminary experiments.

The mixing amount of the dehydrating cyclizing reagent may be appropriately set according to the mixing amount of the polyamic acid. For example, when a tertiary amine is used as the dehydrating cyclizing reagent, the mixing amount is 0 with respect to the amide unit in the polyamic acid. The amount is preferably 0.005 equivalents or more and 0.3 equivalents or less, and more preferably 0.01 equivalents or more and 0.2 equivalents or less. If the tertiary amine is less than 0.005 equivalents, imidization may not proceed sufficiently. On the other hand, adding more than 0.3 equivalents saturates the catalytic effect and is economically disadvantageous. Is concerned. When a carboxylic acid anhydride is also used as a dehydrating cyclization reagent, it is preferably 1 equivalent or more and 20 equivalents or less, more preferably 1.1 equivalents or more, relative to the amide unit in the polyamic acid. 15 equivalents or less. If the amount of carboxylic acid anhydride is less than 1 equivalent, the amide bond may remain and the effect as a dehydrating agent may not be sufficiently exerted. On the other hand, adding more than 20 equivalents saturates the catalytic effect and is economically disadvantageous. There is concern about becoming.
What is necessary is just to set the mixing amount of a solvent suitably so that the density | concentration of a polyamic acid may become the range mentioned above.

  In preparing the polyimide solution, the mixing order of the polyamic acid (polyamic acid solution (A)), the dehydrating cyclization reagent and the solvent is not particularly limited. For example, a mixture of polyamic acid and a solvent (polyamic acid solution ( In contrast to A)), the dehydrated cyclization reagent may be added directly, or the dehydrated cyclization reagent may be dissolved in a solvent and added. Further, the mixing order of both in the case of using a combination of a tertiary amine and a carboxylic acid anhydride as a dehydrating cyclization reagent is not particularly limited, and for example, a tertiary amine and a carboxylic acid anhydride may be added simultaneously, First, either one may be added to a mixture of polyamic acid and a solvent (polyamic acid solution (A)), and after stirring to some extent, the other may be added.

  Mixing of the polyamic acid (polyamic acid solution (A)), dehydrating cyclization reagent and solvent is usually performed at room temperature (for example, 5 to 35 ° C., preferably 15 to 25 ° C.) without special heating or cooling. However, in order to promote imidization, it may be heated in a range of about 100 ° C. or less as necessary.

  When the polyamic acid (polyamic acid solution (A)), the dehydrating cyclization reagent and the solvent are mixed, it is preferable to stir in order to allow the imidization to proceed sufficiently uniformly. As the agitation method, for example, in addition to agitation using a normal agitation blade, a rotation / revolution type mixing method in which rotation and revolution motions are imparted to the object to be mixed is preferably employed. According to this rotation and revolution mixing method, the raw material mixture can be efficiently mixed in a short time, and the contact between each raw material compound can be maintained well, so that the imidization of the imidization can be suppressed and the high imidization rate can be increased. Can be achieved. In addition, according to the rotation and revolution mixing method, defoaming or degassing can be performed at the same time, so that a polyimide solution free from bubbles can be obtained.

  Agitation by the rotation / revolution mixing method may be performed using a commercially available apparatus, or a newly prepared apparatus may be used according to the scale of implementation. The requirement that the apparatus for carrying out the revolution-revolution mixing method should have is that at least a rotation motion and a revolution motion can be given to the container containing the mixing object. Further, in the apparatus for carrying out the rotation and revolution mixing method, the rotation surface and the revolution surface may be parallel, but in order to reduce the load on the device, an angle may be provided on each other surface, for example, An angle of about 10 to 80 degrees may be provided.

  When stirring by the rotation / revolution mixing method, the rotation speed of rotation and revolution is preferably in the range of 0.1 to 5000 rpm, and the rotation speed of rotation and revolution is the same. May be different. Moreover, each rotational speed may be changed, and stirring may be performed at regular intervals. For example, mixing can be performed with a rotation speed of 10 to 2000 rpm and a revolution speed of 100 to 3000 rpm for the main purpose of stirring, and then with a rotation speed of 0 to 1000 rpm and a rotation speed of 100 to 3000 rpm for the main purpose of defoaming. . Specific conditions may be determined according to the implementation scale and the like.

The mixing time for mixing the polyamic acid (polyamic acid solution (A)), the dehydrating cyclization reagent and the solvent is not particularly limited. However, when the rotation / revolution mixing method is used, the mixing proceeds very efficiently. For example, it may be about 1 to 30 minutes. A specific mixing time may be determined by a preliminary experiment.
In preparing the polyimide solution (A), as long as it does not inhibit the imidization reaction, in addition to polyamic acid (polyamic acid solution), dehydrating cyclization reagent, and solvent, for example, a fluororesin (B) described later or Components such as carbon black and various additives to be finally contained in the polyimide composition to be obtained can be mixed at the same time.

  The mixed solution obtained as described above is a polyimide solution (A) containing a polyimide represented by the following formula (II). A polyimide having such a specific structure can exhibit excellent wear resistance and slidability in addition to the properties inherent to polyimide such as high strength and high heat resistance.

［上記式（ＩＩ）中、Ｘ、Ｙ、Ｚ^１、Ｚ^２およびＺ^３の定義と好適な具体例は、化合物（Ｉ）の定義で説明したものと同様とする。］

[In the above formula (II), the definitions and preferred specific examples of X, Y, Z ¹ , Z ² and Z ³ are the same as those described in the definition of compound (I). ]

  The polyimide composition of the present invention includes a fluorine resin (B) together with the polyimide solution (A) described above. In the polyimide solution (A), the polyamic acid used as the raw material of the polyimide has the specific structure described above, and therefore the fluorine resin (B) can be contained with good dispersibility and solubility. As a result, in the present invention, it is possible to improve the slidability of the film formed by containing a larger amount of the fluororesin (B). In addition, when the slidability is improved in a copying or fixing member such as a transfer or fixing roll or belt, the releasability is improved, and a developer such as toner is prevented from adhering to the copying member, and transfer or fixing is prevented. The effect that it becomes easier is also acquired. In general, the fluororesin is preferably contained as a fluororesin particle in the form of particles, and is preferably contained in a dispersed state in the polyimide solution (A) described above.

  As the fluororesin (B), any polymer containing a structural unit derived from an olefin containing a fluorine atom (fluoroolefin) can be used without particular limitation. Here, examples of the fluoroolefin include vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene. Specific examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), tetrafluoroethylene-hexafluoropropylene resin (FEP), tetrafluoride. Preferred examples include ethylene-ethylene copolymer (ETFE), trifluoroethylene chloride resin (PCTFE), trifluoroethylene chloride-ethylene copolymer (ECTFE), perfluorocyclic polymer, and vinyl fluoride resin (PVF). It is done. Only 1 type may be sufficient as a fluorine-type resin (B), and 2 or more types may be sufficient as it.

  When the fluororesin (B) is contained as particles, the particle diameter of the fluororesin particles is not particularly limited as long as it is smaller than the film thickness of the polyimide film to be formed. For example, the center particle diameter is 5 μm or less. More preferably, it is 1 μm or less, and most preferably 0.5 μm or less. When the particle diameter of the fluororesin particles exceeds 5 μm, the surface of the formed polyimide film becomes rough, and as a result, the slidability and the like may be impaired.

Fluorine-based resin (B) (fluorine-based resin particles) may be added to the polyimide solution after imidization, or added together with each raw material (polyamic acid, dehydrating cyclization reagent and solvent) before imidization, You may mix and may add to the polyamic-acid solution (A) previously.
The content of the fluororesin (B) is sufficient to obtain a sufficient slidability improving effect. The mass of the polyimide in the polyimide composition (when polyamic acid is present such as before imidization, the polyamic acid converted to polyimide is used. 25 parts by mass or more, preferably 45 parts by mass or more, and more preferably 65 parts by mass or more with respect to 100 parts by mass. In the present invention, since the polyamic acid has a specific structural unit as described above, the dispersibility and solubility of the fluororesin (B) can be kept good. Thus, it becomes possible to contain a relatively large amount of the fluororesin (B). In addition, since there exists a possibility that the intensity | strength of the polyimide film obtained may fall when there is too much content of a fluorine-type resin (B), content of a fluorine-type resin (B) is the mass of the polyimide in a polyimide composition ( When polyamic acid is present such as before imidization, 150 parts by mass or less is preferable and 100 parts by mass or less is more preferable with respect to 100 parts by mass (total mass obtained by adding the mass of polyamic acid converted to polyimide).

  It is preferable that the polyimide composition of this invention also contains carbon black with the polyimide solution (A) and fluorine resin (B) which were mentioned above. By containing carbon black, for example, when applied to a copying machine member, it can also be provided with antistatic properties, preventing toner and other developers from adhering to the copying machine member, and transferring and fixing. The effect of being easier is obtained. In addition, it is preferable that carbon black is contained in the state disperse | distributed in the polyimide solution mentioned above.

  Any carbon black can be used without particular limitation as long as it is commercially available as conductive carbon black. For example, furnace black produced by continuously pyrolyzing a gas or liquid raw material in a reaction furnace, particularly ketjen black made from ethylene heavy oil, burning a raw material gas and applying the flame to the bottom of the channel steel Examples include channel black deposited by rapid cooling, thermal black obtained by periodically repeating combustion and thermal decomposition using a gas as a raw material, in particular, acetylene black using acetylene gas as a raw material, and carbon nanotubes. Among these, ketjen black, acetylene black, and carbon nanotube are preferable. Only one type of carbon black may be used, or two or more types may be used.

When carbon black is included, the carbon black may be added to the polyimide solution after imidization, or added and mixed together with each raw material (polyamic acid, dehydration cyclization reagent and solvent) before imidization. Alternatively, it may be added in advance to the polyamic acid solution.
The content of carbon black is 20 parts by mass with respect to 100 parts by mass of polyimide in the polyimide composition (when polyamic acid is present, such as before imidization, the total mass obtained by adding the mass of polyamic acid converted to polyimide). The amount is preferably at most 10 parts by mass, more preferably at most 10 parts by mass. When there is too much content of carbon black, there exists a possibility that the intensity | strength of the polyimide film obtained may fall. The lower limit of the carbon black content is not particularly limited, but in order to impart sufficient antistatic properties, it is preferably 1 part by mass or more with respect to 100 parts by mass of the polyimide in the polyimide composition, and 2 masses. Part or more is more preferable.

  The polyimide composition of the present invention further contains various commonly used additives such as a dispersant, an organic solvent, an inorganic filler, a mold release agent, a coupling agent, a flame retardant, and the like, if necessary. As long as it is not impaired, it may be contained as appropriate.

  In the surface modification method for a mechanical member of the present invention, the above-described polyimide composition for surface modification of the present invention is applied to the surface of the mechanical member, and the solvent is removed at a temperature of 250 ° C. or lower. Since the polyimide composition for surface modification of the present invention improves the wear resistance and slidability as well as the strength and heat resistance, the surface modification method is applied to mechanical members that require these characteristics. It is desirable. Examples thereof include mechanical members such as fixing rolls or belts for copying machines, bearings, O-rings, gears, guides, rollers, liners, pulleys, star wheels, slide plates, pallets, and screws. In addition, since the surface modification method of the present invention can form a polyimide film at a low temperature of 250 ° C. or lower, the material of the mechanical member to be applied is not limited, and is made of a general resin or rubber. It can also be applied to members.

  In the surface modification method for a mechanical member of the present invention, it is important to remove (dry) the solvent after applying the polyimide composition of the present invention to a substrate (mechanical member) at a temperature of 250 ° C. or lower. . In the present invention, it is not necessary to calcinate and heat imidize after applying a polyamic acid solution as in the prior art, so the solvent at 250 ° C. or lower (preferably 220 ° C. or lower, more preferably 200 ° C. or lower) is removed. A film can be easily formed simply by drying at a temperature that can be achieved. For example, when dried or baked at a temperature exceeding 250 ° C. at the time of film formation, not only deformation occurs when applied to a substrate (mechanical member) having low heat resistance, but also a fluorine-based resin contained in the polyimide composition ( B) is melted by heat and unevenly distributed on the surface of the base material, which may deteriorate the wear resistance of the surface. In addition, drying does not necessarily need to be heated, and may be performed by a method such as reducing the pressure as necessary at room temperature. Of course, it can be dried at a lower temperature by heating under reduced pressure. What is necessary is just to set drying time suitably according to drying conditions (temperature or pressure).

  There is no restriction | limiting in particular as a coating method at the time of apply | coating the polyimide composition of this invention to a base material (mechanical member), For example, a spin coating method, a casting method, a roll coating method, a spray coating method, a bar coating method, a flexographic method Usual methods such as a printing method and a dip coating method can be employed. Further, the coating amount when applying the polyimide composition of the present invention to a substrate (mechanical member) is preferably such that the dry film thickness is 0.5 μm or more and 50 μm or less, and is 1 μm or more and 30 μm or less. It is more preferable to adjust so.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

Production Example 1 Preparation of Polyamic Acid Solution In a 100 mL three-necked flask, 1.786 g (6.11 mmol) of 1,4-bis (aminophenoxy) benzene as a diamine compound and 2,2 as an acid dianhydride -Bis (3,4- anhydrodicarboxyphenyl) hexafluoropropane 2.714g (6.11mmol) and N-methylpyrrolidone 25.5g as a solvent were added. The mixed solution was stirred at room temperature in a nitrogen atmosphere to obtain a uniform solution, and then allowed to stand for 4 days to obtain a polyamic acid solution. This polyamide solution has a structure represented by the following formula (that is, in the formula (I), X is —C (CF ₃ ) ₂ —, Y is —φ—O—φ—O—φ— (where “ Φ ”represents a benzene ring, O represents an oxygen atom), Z ¹ is a hydrogen atom, Z ² is a hydrogen atom, and Z ³ is a hydrogen atom)). It was.

Example 1
10 g of the polyamic acid solution obtained in Production Example 1 was transferred to a 50 mL glass container, and 415.5 mg (4.06 mmol) of acetic anhydride and 1,4-diazabicyclo [2,2,2] were used as a dehydrating cyclization reagent. ] 6.8 mg (0.061 mmol) of octane (DABCO) was added, and at room temperature, using a rotating / revolving mixer (“AR-250” manufactured by Sinky Corporation) for 10 minutes in a stirring mode, followed by a defoaming mode. After rapidly mixing by stirring for 5 minutes, chemical imidization was performed by leaving still at room temperature for 24 hours to obtain a polyimide solution. When ¹ H-NMR was measured for this polyimide solution, there was no peak due to the carboxyl group of the starting polyamic acid, and no peak corresponding to polyamic acid was found in the ¹⁹ F-NMR measurement. It was confirmed that the chemical imidization proceeded quantitatively.
The agitation by the rotation / revolution mixer is 2,000 rpm and the rotation speed is 800 rpm in the agitation mode, the revolution speed is 2,200 rpm and the rotation speed is 60 rpm in the defoaming mode, and the sample holder is the rotation axis. The inclination was set to 45 degrees with respect to the revolution axis.

  Next, 10 g of the obtained polyimide solution (containing 1.5 g of polyimide), polytetrafluoroethylene (PTFE) dispersion (“KD-1000AS” manufactured by Kitamura Co., Ltd.), dispersion medium: N-methylpyrrolidone, solid content concentration 40%, 2.5 g of PTFE center particle size: 0.3 μm) was added and mixed using the same rotation / revolution mixer as described above to obtain a PTFE-containing polyimide solution.

  Then, separately, in a 200 mL glass container, 98 g of N-methylpyrrolidone as a solvent, 2 g of ketjen black (“Carbon ECP600JD” manufactured by LION), and polyvinylpyrrolidone (“K-30” manufactured by Nippon Shokubai Co., Ltd.) as a dispersant. ) 0.4 g was added together with beads having a diameter of 1 mm, subjected to a dispersion treatment with a paint shaker for 1 hour, and then filtered to prepare a carbon black dispersion liquid having a solid content concentration of 2%. 1.55 g of this carbon black dispersion was added to 10 g of the PTFE-containing polyimide solution and mixed using the same rotation / revolution mixer as described above to obtain a polyimide composition containing PTFE and carbon black.

Next, the obtained polyimide composition was coated on a film, and the abrasion resistance of the formed polyimide film was evaluated.
That is, after applying the polyimide composition on a Kapton (registered trademark) film (manufactured by Toray DuPont) using a spin coater (manufactured by Mikasa) so as to have a dry film thickness of 15 μm, it is performed at 200 ° C. for 1 hour. By drying, a film coated with a polyimide film was produced.

  The obtained film was cut into 10 mm × 70 mm, and the mass was precisely weighed. Then, using a polishing apparatus (“Doctor Wrap ML-180” manufactured by Marto), the coated surface of the film was # 2000 sandpaper. Polishing was performed for 45 seconds under the conditions of a polishing disk rotation speed of 20 rpm and an arm rotation speed of 77 rpm. When the mass of the film after polishing was precisely weighed, the mass decreased after polishing was 3.6 mg.

(Comparative Example 1)
10 g of the polyamic acid solution obtained in Production Example 1 was added to a polytetrafluoroethylene (PTFE) dispersion (“KD-1000AS” manufactured by Kitamura Co., Ltd., dispersion medium: N-methylpyrrolidone, solid content concentration 40%, PTFE center particle size : 0.3 μm) was added and mixed using the same rotation / revolution mixer as in Example 1 to obtain a PTFE-containing polyamic acid solution.

  Next, 1.55 g of a carbon black dispersion separately prepared in the same manner as in Example 1 was added to 10 g of the PTFE-containing polyamic acid solution and mixed using the same rotation / revolution mixer as in Example 1, and PTFE and carbon black were mixed. A polyamic acid composition containing was obtained.

Next, the abrasion resistance of the polyimide film formed by coating the obtained polyamic acid composition on a film and thermally imidizing by heating during drying was evaluated in the same manner as in Example 1.
That is, after applying the polyamic acid composition on a Kapton (registered trademark) film (manufactured by Toray DuPont) using a spin coater (manufactured by Mikasa) so as to have a dry film thickness of 15 μm, By drying for a time, a film coated with a film was produced. The film was cut into 10 mm × 70 mm, and the mass was precisely weighed. Then, the coated surface of the film was polished in the same manner as in Example 1, and the mass of the polished film was precisely weighed. Was 8.8 mg, which was clearly inferior to Example 1 in terms of wear resistance. This is because, when a polyimide film is formed by imidizing a polyamic acid solution with heat, imidation is insufficient only by heating (drying) at a low temperature enough to remove the solvent as in Example 1, and the film is originally developed. It shows that the possible performance (abrasion resistance equivalent to Example 1) cannot be exhibited.

(Reference Example 1)
The polyamic acid composition obtained in Comparative Example 1 was coated on a film, and the wear resistance of a polyimide film formed by thermal imidization by heating at a high temperature during drying was evaluated in the same manner as in Example 1.
That is, the polyamic acid composition obtained in Comparative Example 1 was applied onto a Kapton (registered trademark) film (Toray DuPont) using a spin coater (Mikasa) so that the dry film thickness was 15 μm. Then, a film coated with a polyimide film was produced by drying at 320 ° C. for 1 hour. The film was cut into 10 mm × 70 mm, and the mass was precisely weighed. Then, the coated surface of the film was polished in the same manner as in Example 1, and the mass of the polished film was precisely weighed. Was 3.7 mg.

(Reference Example 2)
Spin coater (manufactured by Mikasa Co., Ltd.) with a polyimide composition containing PTFE and carbon black obtained in Example 1 on a Kapton (registered trademark) film (manufactured by Toray DuPont) so that the dry film thickness is 15 μm. Then, the film coated with a polyimide film was produced by drying at 350 ° C. for 1 hour.

  About the obtained film, when abrasion resistance was evaluated similarly to Example 1, the mass decreased after grinding | polishing was 7.8 mg. This is because the fluororesin having poor wear resistance contained in the polyimide composition starts to melt by heating during drying and is unevenly distributed on the surface of the film.

Claims (8)

A surface comprising a polyimide solution (A) and a fluororesin (B) obtained by mixing a polyamic acid having a structure represented by the following formula (I), a dehydrating cyclization reagent, and a solvent: Polyimide composition for modification.

[In the above formula (I), X represents a divalent organic group which may be substituted with a halogen atom; Y represents a divalent organic group; Z ¹ , Z ² and Z ³ are independently of each other. One of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom is shown. ]   The polyimide composition for surface modification according to claim 1, wherein the dehydrating cyclization reagent is a tertiary amine or a combination of a tertiary amine and a carboxylic acid anhydride.   The polyimide composition for surface modification according to claim 1 or 2, wherein the solvent is at least one selected from the group consisting of N, N-dimethylacetamide, N, N-dimethylformamide and N-methylpyrrolidone.   The content of the said fluororesin (B) is 25 mass parts or more with respect to 100 mass parts of polyimides in a polyimide solution (A), The polyimide composition for surface modification in any one of Claims 1-3 .   The surface-modifying polyimide composition according to claim 1, which also contains carbon black.   The polyimide composition for surface modification according to any one of claims 1 to 5, wherein the structure represented by the formula (I) contains one or more carbon atom-halogen atom bonds.   X in the formula (I) is one selected from the group consisting of a di-trifluoromethyl-methylene group, a p-dioxy-phenylene group, and a p-dioxy-tetrafluorophenylene group. The surface-modifying polyimide composition according to any one of the above.   A surface modification method for a mechanical member, wherein the surface-modifying polyimide composition according to claim 1 is applied to the surface of the mechanical member, and the solvent is removed at a temperature of 250 ° C or lower.