JP2003306553A - Molded polyimide article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a molded polyimide article of which the electric resistance is stable at from normal temperature and humidity to high temperature and humidity, can be easily controlled into a medium range, and exhibits little variation among samples or due to the change of place, amount of a semiconductive filler incorporated, voltage, and environment and which is excellent in surface properties and mechanical characteristics. <P>SOLUTION: The molded article is obtained from a polyimide resin composition which contains an inorganic filler having a volume resistivity of 1×10<SP>3</SP>-1×10<SP>10</SP>Ωcm and has a volume resistivity of 1×10<SP>6</SP>-1×10<SP>13</SP>Ωcm. The surface roughness of the article is such that Ra is 0.01-0.5 μm and Rz is 0.05-2.5 μm. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide molded body, and more specifically to a polyimide molded body made of a polyimide resin composition having a controlled intermediate resistance value and having excellent surface smoothness.

[0002]

2. Description of the Related Art Polyimide resin has excellent heat resistance,
Taking advantage of its chemical resistance and electrical insulation properties, the film,
Widely used as molded products such as tubes and belts. For example, various applications such as film-like insulating base materials such as FPC or TAB base materials or electric wires, parts of OA equipment such as copying machines such as tubes and belts, and molded products such as separating claws and bearings of copying machines. Is used for. Further, in recent years, it is being used for adhesives, protective films, etc. around the semiconductor by taking advantage of its characteristics.

By the way, electronic copying of printers, copying machines, etc.
Transfer belts / intermediate transfer belts / fixing bells for true applications
For polyimide moldings such as
It is desirable to have an intermediate resistance value for wearing. This place
The required resistance is 10 ⁶-10¹³Ω · cm, preferred
It is 10⁷-10¹³Ω · cm, more preferably 10 ⁹
-10¹³Ω · cm. Also, resistance in all environments
The value is preferably constant. Specifically, at low temperature and low humidity
And the resistance ratio at high temperature and high humidity is 100 times or less, and further 3
It is 0 times or less. Also, depending on the image type and environment,
It is necessary to control the pressure and current, and to adjust the resistance value according to the voltage.
If it fluctuates, it will be difficult to control.
The smaller the possibility, the better. Specifically, 100V and 1
The ratio of the resistance value of 000V is 100 times or less, more preferably
Is 30 times or less. In addition, toner attached to the belt surface
Blades for scraping and improving toner transfer efficiency
Therefore, the belt surface must have excellent smoothness,
The center line average roughness Ra according to JIS B 0601 is 0.
5 μm or less, 10-point average roughness according to JIS B 0601
Rz is 2.5 μm or less, preferably Ra is 0.4 μm or less
Below, Rz is 2.0 μm or less.

In view of such requirements, various attempts have been made to reduce the resistance value of the molded product by adding various conductive substances to the polyimide resin. For example, Japanese Patent Laid-Open No. 2-1101
No. 38 discloses a product containing an aromatic polyimide matrix and a finely divided electrically conductive particle material, in which the particle material is uniformly dispersed, and 10 to 45% by weight of the whole is present. Further, in Japanese Patent Laid-Open No. 63-311263, the surface resistance (Ω /
□) is an intermediate transfer member for an electrophotographic recording device, characterized by comprising an aromatic polyamide film or an aromatic polyimide film having a range of 10 ⁷ ≤Rs ≤10 ¹⁵ . Further, in Japanese Patent No. 2785537, a film made of a composition containing an aromatic polyimide and a conductive inorganic filler, having a volume resistance value of 10 ^-2.
A transparent conductive film characterized by having a total light transmittance of 10 ¹² Ω · cm and 20% or more is shown.

Since carbon black, graphite, metal particles, indium oxide, etc. as described above have an extremely low electric resistance value (less than 1.0 × 10 ³ Ω · cm), the polyimide molded body has an intermediate resistance value. Therefore, the compounding amount required is small, and the surface smoothness of the molded product is not significantly impaired. However, it is very difficult to stably control the resistance in the semi-conductive region by using these low resistance conductive materials, and it is particularly difficult to make the resistance values reproducible and reduce the in-plane variation. It was very difficult. Moreover, only those having a large dependency of the resistance value on the measured voltage and the number of added parts were obtained. As described above, the polyimide molded body in which a conductive filler such as carbon or metal is added to adjust the intermediate resistance value region is difficult to stably control the resistance value,
It was also difficult to optimize the amount added.

[0006]

As a result of investigating a method for stably controlling a polyimide molded body in a region of an intermediate resistance value, a semiconductive inorganic filler is used for controlling the resistance value of a polyimide resin composition, and it is stable. It was found that effective resistance control is possible.

However, in order to control the resistance value by this method, it is necessary to add a large amount of a semiconductive inorganic filler as compared with the case where a conductive filler is used, and as a result, the surface of the polyimide molded body is mixed. It was found that the smoothness deteriorates.

Therefore, the problem to be solved by the present invention is to improve the surface smoothness of a polyimide molded body which is controlled to have an intermediate resistance value by using a semiconductive filler.

[0009]

[Means for Solving the Problems] In order to solve the above problems,
As a result of diligent study, it has an intermediate resistance value, small variation between samples, small surface roughness, little environmental dependence and voltage dependence of resistance value, and excellent transferability and fixing property in an electrophotographic machine. The inventors have found a method for obtaining a polyimide molded body and completed the present invention.

That is, according to the present invention, the volume resistance value is 1 × 10.
^The polyimide resin composition has a volume resistance value of 1 × 10 ⁶ to 1 × 10 ¹³ Ω · cm and contains an inorganic filler of ³ to 1 × 10 ¹⁰ Ω · cm, and has a center line average roughness Ra of 0.0.
1 μm or more and 0.5 μm or less, ten-point average roughness Rz is 0.0
Provided is a polyimide molded body having a thickness of 5 μm or more and 2.5 μm or less.

Preferably, the inorganic filler is a needle-like filler having a minor axis diameter of 0.05 μm or more and 1 μm or less and a major axis diameter of 7.5 μm or more and 100 μm or less, and its content is 100 parts by weight of polyimide resin. For 0.1 to 7
0 parts by weight.

Also, preferably, the volume resistance value of the inorganic filler is 1 × 10 ³ to 1 × 10 ⁸ Ω · cm.

In one embodiment, the polyimide resin composition has a particle size of 0.0
Volume resistance value of 1 x 10 ^-5 when the thickness is between 05 μm and 1.0 μm
It contains a granular inorganic filler having a density of ˜1 × 10 ¹⁰ Ω · cm, and the content thereof is preferably 0.01 to 150 parts by weight with respect to 100 parts by weight of the polyimide resin.

In one embodiment, in addition to the needle-shaped filler, the polyimide resin composition has a minor axis diameter of 0.005 μm or more and 1.0 μm or less and a volume resistance value of 1 or less.
It contains a scale-like inorganic filler having a density of × 10 ^-5 to 1 × 10 ¹⁰ Ω · cm, the content of which is preferably polyimide resin 10
It is 0.01 to 50 parts by weight with respect to 0 parts by weight.

Further, in one embodiment,
In addition to the acicular filler, the polyimide resin composition has a minor axis diameter of 0.005 μm or more and 1.0 μm or less and a volume resistance value of 1 × 10 ⁻⁵ to 1 × 10 ³ (1 × 10 ⁻⁵ or more 1 ×
An acicular inorganic filler having a resistivity of less than 10 ³ Ω · cm is contained, and the content thereof is preferably 0.01 to 50 parts by weight with respect to 100 parts by weight of the polyimide resin.

Here, the polyimide resin is preferably a reaction-curing linear polyimide resin, and the polyimide resin is heated and calcined after adding an acid anhydride and / or a tertiary amine as an imidization promoter to polyamic acid. The polyimide resin thus obtained is preferred.

The polyimide molding of the present invention may be in the form of a film or a tube, and preferably has a thickness of 10 μm or more and 100 μm or less.

Further, the polyimide molded article of the present invention is preferably used for transfer, intermediate transfer, transfer fixing or fixing of an electrophotographic apparatus.

In the present specification, the minor axis diameter, major axis diameter and particle diameter all represent the average minor axis diameter, average major axis diameter and average particle diameter of the filler, and the minor axis diameter is The major axis diameter corresponds to the thickness of the needle-shaped filler, and the major axis diameter is a numerical value corresponding to the length of the needle-shaped filler. The minor axis diameter of the scale-like filler refers to the average thickness of the scale-like filler.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The polyimide resin in the present invention refers to any resin having an imide bond in its structure,
This includes not only resins called by general names such as polyetherimide, polyesterimide, and polyamideimide, but also copolymerization systems and blends with other resins. In particular, a reaction-curable linear polyimide resin that is strongly bonded to the inorganic filler and is easy to orient the acicular inorganic filler in the plane of the film is preferable. Here, the reaction-curable linear polyimide resin refers to a polyimide resin obtained by dehydration ring closure of an amic acid site via a linear polyamic acid as a precursor, and pyromellitic acid diimide A typical example is a polyimide resin obtained by heating, adding a catalyst, or the like to a linear polyamic acid obtained by reacting an anhydride with 4,4′-diaminodiphenyl ether. The reaction-curing linear polyamic acid has a functional group such as a carboxyl group or an amino group, and these functional groups strongly interact with the inorganic filler and can form a strong bond with the inorganic filler. It is preferably used. Furthermore, when an acid anhydride and / or a tertiary amine is used as an imidization accelerator, a polyimide molded product having a strong tear during molding and after molding can be obtained as compared with the case of heat curing, and the molding time can be significantly increased. Shortened. Further, since imidization progresses faster than thermal curing, the resin becomes rigid quickly and is easily oriented in the in-plane direction. As a result, the added filler is also oriented in the in-plane direction, the surface resistance value and the surface roughness are small, and a polyimide molded body having excellent insulating properties in the thickness direction can be obtained.

As a raw material for general polyimide, it is usual to use a diamine compound and tetracarboxylic dianhydride as monomers. As the diamine compound, for example,

[0022]

[Chemical 1]

(Wherein, X is the same or different and
-CH₃, -OCH₃, -O (CH ₂)_nCH₃,-
(CH₂)_nCH₃, -CF₃, -OCF₃From the group consisting of
Represents at least one group selected. Also, A is the same.
Or, differently, O, S, C = O, (CH₂)_n, SO₂,
Represents at least one group selected from the group consisting of N = N
You n is an integer of 1 or more. ) Various monomers shown in
You can Also, as tetracarboxylic dianhydride
Is

[0024]

[Chemical 2]

Various monomers shown in the formula (n is an integer of 1 or more) can be used. Various characteristics can be brought out by combining these, and it can be selected according to the situation such as application and processing method.

For example, using an aromatic diamine containing many bent chains (preferably two or more in one molecule) and / or having an amino group in the meta position, and using a tetracarboxylic dianhydride having two or more rings. Thus, it is possible to provide a polyimide resin composition which can be made into a thermoplastic polyimide and can be melt-molded by heating. For example, 2,2'-bis (4-
Aminophenoxyphenyl) propane in combination with oxydiphthalic dianhydride, bis (2- (4-aminophenoxy) ethoxy) ethane in 3,3 ', 4,4'-
Examples thereof include a combination of benzophenone tetracarboxylic acid dianhydride.

Polyimide usually has a high water absorption rate due to the presence of imide groups, but it can be made into a resin composition having a relatively low water absorption rate in combination with a specific monomer. As an example, a polyimide using a monomer having a structure in which a plurality of benzene nuclei are bound by two or more ester bonds as a tetracarboxylic dianhydride can be mentioned. In particular,

[0028]

[Chemical 3]

(In the formula, n is an integer of 1 or more.)

[0030]

[Chemical 4]

[0031]

[Chemical 5]

Acid dianhydrides such as those shown in are included. As the diamine compound used in this case, it is preferable to use a relatively long-chain monomer in order to reduce the imide group content. For example, 1,4-bis (4-aminophenoxy) benzene and its bond position isomer, 2,2
′ -Bis (4-aminophenoxyphenyl) propane and the like can be mentioned. However, for both the acid dianhydride and the diamine, the structure having a long chain and a large number of bent chains is also a condition for exhibiting the above-mentioned thermoplasticity, and is not suitable when sufficient heat resistance is required. Particularly when both heat resistance and low water absorption are required, a long-chain monomer having a linear structure wholly or partially is suitable. For example, as tetracarboxylic dianhydride,

[0033]

[Chemical 6]

An example is a monomer (TMHQ) having a structure represented by: It has been found that this monomer has a structure in which it contains a bent chain and can take a substantially linear conformation as a whole, and it forms a relatively rigid polyimide in spite of the large number of bonds. If this raw material is used, the coefficient of linear expansion is 15 ppm or less and the water absorption rate is 1.5%.
Hereinafter, it is also possible to obtain a polyimide resin having a hygroscopic expansion coefficient of 10 ppm or less and less dimensional change due to heating or moisture absorption. Further, as the diamine, for example, a structure in which a biphenyl structure or a naphthalene structure is connected by an ether bond can be selected as a relatively rigid structure although it has a long chain. For example, 4,4′-bisaminophenoxybiphenyl and the like. By combining these acid dianhydrides and diamines,
It is possible to obtain a polyimide having a relatively low water absorption and not having a remarkable thermal softening property. Further, not only these monomers but also general-purpose pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, paraphenylenediamine, 4,4'-diaminodiphenyl ether and the like are appropriately copolymerized to obtain a wide range of polyimides having desired properties. It can be designed.

The coefficient of linear expansion of polyimide is larger than that of a metal such as copper. However, even if the type and composition ratio of the monomers are the same, it is possible to obtain a resin composition having a relatively small linear expansion coefficient by controlling the combination (sequence control) of the connection of the monomers. For example, in comparison with the case where 4,4′-diaminodiphenyl ether, paraphenylenediamine, and pyromellitic dianhydride are randomly copolymerized, 4,4′-diaminodiphenyl ether and pyromellitic dianhydride are previously reacted with each other. Then, a procedure of adding para-phenylenediamine is followed to obtain a polyamic acid having a regular monomer arrangement, and a polyimide having a low linear expansion coefficient can be obtained by imidization.

In the present invention, since an inorganic filler is mixed with the polyimide resin, higher toughness is required for the polyimide as compared with the case where the polyimide is used alone. If the toughness of the polyimide itself is not sufficient, the toughness inevitably decreases due to the addition of the inorganic filler, and it may not be practically available. In that respect, the most preferable is a polyimide composed of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether. This structure is a well-balanced structure that has both sufficient heat resistance and high toughness and can maintain its characteristics under a wide range of processing conditions.

The inorganic filler compounded in the above-mentioned polyimide resin used in the present invention may have a volume resistance value of from low resistance value to medium resistance value, but low resistance conductive material such as carbon black, graphite and metal pieces. 1 higher than material
× 10 ³ to 1 × 10 ¹⁰ Ω · cm is preferable, 1 × 10 ³ to 1 × 10 ⁸ Ω · cm is more preferable, and 1 is particularly preferable.
It is a volume resistance value of × 10 ³ to 1 × 10 ⁷ . Generally, when a conductive material having a low resistance value is added to a resin, an intermediate resistance can be realized even if added in a small amount. Therefore, the deterioration of the surface property of the molded body can be suppressed to a small extent, but there is a large difference in the resistance value between the resin and the conductive material. The breakdown voltage is also low. However, in the case of a needle-shaped inorganic filler having a low resistance value, it is difficult to deteriorate the dielectric breakdown property by orienting it in the in-plane direction.

The reason why the medium resistance value can be stably controlled by using the semiconductive inorganic filler, and the variation in the resistance between the compounding parts, the dispersion state, and the samples can be reduced is as follows, though not sure. Thinking to

The semiconductive filler is 1 × 10 ³ to 1 by itself.
It has a resistance of × 10 ¹⁰ Ω · cm, carbon black, conductive metals and metal ceramics (1 × 10 ⁻⁵ to 1 × 10 ³
Ω ・ cm), the resistance value is the target medium resistance value (1 ×
It is close to 10 ⁶ to 1 × 10 ¹³ Ω · cm). As a result, even if it is added excessively, the resistance does not drop to a low resistance value too much, the resistance is saturated near the middle resistance value, and it is possible to stably control the middle resistance value. In addition, in the system to which the semiconductive filler is added, a sharp decrease in resistance due to percolation as seen in carbon black is not seen, and the resistance changes gently with respect to the addition amount. As a result, in the system in which the semiconductive filler is added, the resistance value does not change three times even if the addition amount changes by about 5 parts by weight with respect to the number of addition parts whose resistance is controlled in the medium resistance region. Even if the filler is aggregated or biased during the defoaming or dispersing process, the resistance is not significantly changed. From these facts, it can be said that the semiconductive filler is a material in which the resistance of the composition changes little even if the addition amount and dispersion state in the resin composition vary among the samples.
On the other hand, in the system to which carbon black is added, in order to control the medium resistance region, 10 to 2 is added to 100 parts by weight of the resin.
Although about 0 parts by weight is added, when the number of added parts changes by about 5 parts by weight with respect to such a small number of added parts, the resistance immediately changes by 10 to 100 times or more. As a result, the number of blended parts, the state of dispersion, and slight differences between lots significantly affect the resistance value.

Further, the reason why the insulating property is improved by using the semiconductive filler is considered as follows, although not sure.

It is considered that when a voltage is applied to a film made of polyimide and a conductive material, the voltage is divided between the polyimide and the conductive material, and the voltage is applied to a portion of the polyimide having a higher resistance than the conductive material. In particular, comparing the case of adding a low resistance material such as carbon black or a metal-based material and the case of adding a medium resistance material such as a semiconductive filler, the voltage applied to the polyimide was obtained by adding the medium resistance material. It seems that the time is smaller. As a result, it is considered that the dielectric breakdown in polyimide is reduced.

Further, the reason why the voltage dependence and the environment dependence of the resistance are improved by using the semiconductive filler is considered as follows.

Generally, a high voltage (for example, a thickness of 100 μm) is applied to a resin.
When a voltage of 1 kV or more is applied to m),
The resin approaches dielectric breakdown, and the voltage dependence of the resistance value deteriorates rapidly. That is, a large current flows just before the destruction. From this, it can be considered that the voltage dependency of the resistance value is a phenomenon that occurs when the resin approaches destruction due to the high voltage applied to the resin. However, in a system to which a medium resistance material such as a semi-conductive filler is added, it is possible to prevent a high voltage from being locally applied to the resin portion as compared with the case where a low resistance material such as carbon black is added. I think that the voltage dependence of the resistance value can be improved. In addition, most of the semiconductive fillers partially have hydroxyl groups or active oxygen on the surface, and cause strong interaction with the resin during imidization without surface treatment, and become a strong composite material. It is considered that these strong composite materials are also useful for preventing a decrease in resistance value and deterioration of insulation property at high temperature and high humidity.

Although considered to be due to the above reasons, the following electrical characteristics can be realized by using a semiconductive filler. First, a volume resistance value of 1 × 10 ⁶ to 1 × 10 ¹³ Ω · cm can be stably obtained by appropriately mixing these.
It is preferably 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm, and has a surface resistance value of 10 ⁶ to 10 ¹³ Ω / □, preferably 1 × 10 ⁹ to 1 × 1.
An intermediate resistance value of 0 ¹³ Ω / □ can be realized. Further, the resistance value Rl at low temperature and low humidity and the volume resistance value R at high temperature and high humidity
The ratio of h (Rl / Rh) can be controlled in the range of 0.01 to 100, more preferably 0.3 to 30, and a material having excellent environmental stability can be prepared. Further, the ratio (R _100V / R _1000V ) of the volume resistance value R _100V when _100V is applied to the volume resistance value R _1000V when 1000V is applied is 0.01 to 10
It can be controlled within a range of 0, and more preferably within a range of 0.3 to 30, and a material having little voltage dependency can be adjusted.
Further, within the range of the number of added parts that realizes the resistance value, the variation of the volume resistance is 3 times or less even if the number of added parts of the semiconductive filler changes by 5, and it is possible to adjust a material having little dependency on the number of added parts. it can. Further, it is possible to suppress the variation in the resistance value between the samples to 3 times or less, and it is possible to adjust the material having the small variation between the samples.

[0045] As the resistance value of the semiconductive filler used in the present invention is ^{1 × 10 3 ~1 × 10 1} 0 Ω · cm is good,
It is preferably 1 × 10 ³ to 1 × 10 ⁸ Ω · cm, and particularly preferably 1 × 10 ³ to 1 × 10 ⁷ Ω · cm. Examples of the semiconductive filler satisfying this resistance value include titanium oxide, metal titanate, aluminum borate, tin oxide, and silicon carbide.

Inorganic fillers whose surface is coated with a conductive substance can also be used. Specifically, black conductive substances such as carbon and graphite, ITO (indium-tin composite oxide), A
TO (anti-moly-doped tin oxide), NTO (niobium-doped tin oxide), TTO (tantalum-doped tin oxide), FTO
Semi-conductive fillers coated with a tin oxide-based conductive material such as (fluoride-doped tin oxide) and TO (tin oxide) can be given. Of these, a material coated with a black conductive material or a tin oxide-based conductive material is preferable because it can be adjusted to various medium resistances depending on the type, amount, and forming method of the conductive material.

For example, in the case of a material whose resistance is controlled by a black conductive material such as carbon or graphite, the resistance can be controlled by adjusting the coating amount of the black conductive material attached to the surface. Further, even if a material having a low resistance is obtained once, the resistance is increased by heating in air at a temperature of 50 to 750 ° C., and a semiconductive substance having various resistance values can be easily obtained.

In the case of a material whose resistance is controlled by tin oxide or doped tin oxide, it is possible to control widely from low resistance to high resistance by changing the amount of doping. The resistance can also be controlled by forming a tin oxide layer or a doped tin oxide layer on the surface of the core material and then selecting the heating atmosphere as either oxidizing or non-oxidizing or changing the heating temperature. be able to. In this way
It is possible to easily obtain a semiconductive material having various resistance values having similar shapes. Further, the tin oxide-based material is resistant to heat, and does not cause physical property deterioration even in severe molding exceeding 300 ° C. such as a polyimide film-forming step, so that it can be used in a wide range. Further, tin oxide-based materials are nearly colorless, and if a colorless core material is used, a colorless semiconductive filler can be obtained. as a result,
By using a colorant together, polyimide resin compositions having various colors can be obtained.

Further, by controlling the surface coating method as described above, there are the following merit that the resistance can be controlled. For example, materials such as potassium titanate, tin oxide, and zinc oxide have only specific resistance values, and when these are used to control various resistances, two or more kinds of materials having different resistance values are used. Mix fillers,
It was necessary to change the number of blended parts. Further, it requires a great deal of labor to control the dispersibility and adjust the blending according to each filler, and the mechanical properties differed by changing the blending amount. Further, there is only a single color, and there is little freedom in changing the color when applying various colors. However, if the material coated with the conductive substance of the present invention is used, a material having various resistances can be easily prepared from a single material, and the conductivity can be controlled without changing the mechanical characteristics or dispersibility. Therefore, polyimide resins having the same compounding amount but different resistance values can be prepared. In addition, since basic properties such as mechanical properties and dispersibility of semi-conductive inorganic materials using the same core material are almost the same, cleaning work and switching work by changing the type become very easy. In addition, depending on the method of conducting the surface, a wide range from colorless to black can be selected, and coloring is facilitated.

As the core material (inorganic material) of the semiconductive filler coated with the conductive material used in the present invention, metal,
Examples thereof include ceramic materials such as metal oxides, metal carbides, and metal nitrides, and metal salts. For example, zinc, zinc oxide, aluminum, alumina, aluminum hydroxide, calcium, calcium carbonate, silver, chromium oxide, silicon, silicate, calcium silicate, silica, glass, titanium oxide, metal titanate, aluminum borate. , Tin oxide, iron, iron oxide, copper, copper oxide, barium carbonate,
Barium sulfate, barium hydroxide, magnesium, magnesium hydroxide, silicon carbide, tungsten carbide, titanium carbide, aluminum nitride, silicon nitride, germanium nitride, tantalum nitride, titanium nitride, boron nitride, mica,
Examples thereof include talc, wollastonite, talc, kaolin, and clay minerals.

Zinc oxide, titanium oxide and metal titanate have a high refractive index and a high hiding rate. In particular, titanium oxide has a refractive index of 2.5 or more and a high concealment ratio, and has the property of making the material white. When added to polyimide, the material becomes yellow. Further, even if another black additive such as carbon black or an organic pigment is added, it does not become black easily.

On the other hand, aluminum borate, tin oxide, calcium carbonate, silicate, calcium silicate, barium sulfate, and mica have a small refractive index unlike titanium oxide and metal titanate, and are close to the refractive index of resin. Therefore, it is preferable that it is less likely to be mixed with the resin to impair the transparency and that it is not colored. In addition, alumina, silica,
Glass, wollastonite, talc, and kaolin also have a relatively low refractive index, and transparency is unlikely to be impaired when added to a resin. The refractive index is 2.0 or less, preferably 1.8 or less, and more preferably 1.7 or less. When this is coated with a black conductive substance, a blackened semi-conductive inorganic substance can be obtained, and a black polyimide resin composition is easily obtained after compounding with a polyimide, which is preferable. In addition, when the tin oxide-based material is coated, a semiconductive filler having excellent transparency can be obtained, and the polyimide resin added with this filler has transparency. In addition, it is preferable to add another colorant because an arbitrary color tone can be obtained.

Further, the smaller the amount of metal component released from the core material, the better. The amount of free metal component is 100 ppm or less,
Preferably 80 ppm or less, more preferably 50 pp
It is good that it is m or less. Within these ranges, the free metal component is small and the humidity dependency of the resistance value of the compounded resin is reduced, which is preferable. In addition, the dielectric breakdown voltage is also small, which is preferable.

The semiconductive filler used in the present invention is preferably acicular, and its minor axis diameter is 1 μm or less, preferably 0.75 μm or less, more preferably 0.5 μm.
It is the following. The major axis diameter is 7.5 μm or more, preferably 10 μm or more, more preferably 15 μm or more. However, on the other hand, if the minor axis diameter is too small or the major axis diameter is too large, it is difficult to maintain the shape, so the minor axis diameter is 0.05 μm or more and the major axis diameter is 100 μm.
m or less is realistic.

Usually, in a molded product obtained by mixing these with a general-purpose resin and molding them by an extrusion method or an injection method, a filler having a long major axis is excellent in reducing the resistance, but deteriorates the insulating property, and the surface of the molded product is deteriorated. Protruding to the outside, deteriorating the surface property. Therefore,
Achieving good electrical properties and low surface roughness is very difficult. Further, in order to obtain a molded product having a small surface roughness by using a needle-shaped filler, it is usual to add a needle-shaped filler having a large minor axis and a small major axis, which is more granular (spherical). It was The reason why the needle-like filler deteriorates the surface property is that the major axis of the filler projects to the surface, and the smaller the major axis diameter, the smaller the projecting amount. It is also possible to add a filler having a small particle size to make the surface smooth, but the filler having a small particle size is inferior in the effect of reducing resistance. Therefore, in order to reduce the resistance to the target medium resistance value, it is necessary to add a large amount of granular filler, which deteriorates the surface smoothness.

Although the scale-like filler is inferior to the acicular filler, it has a much larger resistance reducing effect than the granular filler.

The polyimide resin used in the present invention is likely to undergo in-plane orientation during molding. Further, in a preferred embodiment, the polyamic acid solution is extruded from a die having a clearance of about 1 mm or less during molding, so that the resin is more easily oriented in the in-plane direction. With the orientation of the resin, the needle-like filler mixed with the resin is also oriented in the in-plane direction, and the orientation of the filler in the in-plane direction is more likely to proceed than in ordinary extrusion or injection molding. Furthermore, in the case of molding a polyimide from a polyamic acid solution, drying of the solvent occurs while the orientation of the resin is progressing, so even in this drying process, the acicular filler is further oriented in the in-plane direction, It is presumed that it is possible to obtain a polyimide molding having a large inward orientation.
As described above, in the molding of polyimide, it is considered that the filler is more likely to be oriented in-plane than in the usual molding method, because it undergoes three processes of thin film casting or extrusion, early imidization of polyimide, and drying of the solvent.

The preferred major axis diameter of the needle-shaped filler in relation to the thickness of the polyimide molding is 10% or more, preferably 20% or more, of the major axis diameter. , Is preferable for promoting the in-plane orientation.

The influence of the shape of the needle-shaped semiconductive filler used in the present invention on the electrical characteristics is as follows.
Since the major axis diameter is as long as 7.5 μm or more, it is easy to contact each other, and it is possible to control the resistance to the medium resistance region even if the blending amount is small, which is preferable. However, when the major axis diameter becomes longer,
Although the electrical insulation deteriorates, if thin film casting is used as the molding method and polyimide resin is used as the resin, the orientation in the in-plane direction of the needle-shaped semiconductive filler proceeds, and the contact in the thickness direction can be reduced, resulting in the insulation property. It can prevent the deterioration. On the other hand, when the major axis is shorter than 7.5 μm, the contact between the fillers is reduced and the effect of reducing the resistance is inferior, which is not preferable.
In addition, the orientation in the in-plane direction does not proceed, and the insulating property deteriorates.

Since the minor axis diameter of the acicular semiconductive filler used in the present invention is 1 μm or less, the insulating property is not deteriorated even if there is some aggregation, which is preferable. on the other hand,
When the minor axis diameter is larger than 1 μm, dielectric breakdown occurs due to local aggregation due to poor dispersion, which is not preferable. In addition, since this material has a short minor axis diameter and a long major axis diameter, the aspect ratio becomes large, the number of whiskers for the same volume increases, contact between fillers appropriately occurs, and the resistance reducing effect is excellent. It is preferable because the amount of filler added can be reduced. In addition, thin film materials obtained by extrusion molding using general-purpose resins (usually 10 μm or more and 100 μm
m or less), the surface resistance value is higher than the volume resistance value, but in the present invention, since the filler is oriented in the plane and the contact in the surface direction is increased, the surface resistance value is higher than the volume resistance value. Also, it becomes easy to obtain a resin composition having a small surface resistance value.

The influence of the shape of the acicular semiconductive filler used in the present invention on the surface roughness is as follows. Since the major axis diameter is as long as 7.5 μm or more, the orientation in the in-plane direction proceeds, and the portion protruding from the film is reduced, so that the surface roughness is easily obtained. On the other hand, when the major axis diameter is shorter than 7.5 μm, it becomes difficult for the surface orientation to proceed, and the surface property tends to be poor. Further, if the minor axis diameter is 1 μm or less, the surface roughness becomes small, which is preferable. This is because even if the needle-shaped semiconductive filler is completely oriented in the plane, the filler existing near the surface of the film or belt is not always completely covered with the resin and a part thereof is projected. It becomes a shape. In this case, it is considered that the thickness of the minor axis diameter directly affects the surface roughness. However, if the thickness is 1 μm or less, the surface roughness can be minimized, which is preferable. On the other hand, 1 μm
If it is above, surface roughness will deteriorate significantly. As described above, by increasing the major axis diameter and shortening the minor axis diameter, the target surface roughness Ra of 0.5 μm or less, Rz 2.5 μm or less, and more preferably Ra 0.4 μm or less and Rz 2.0 μm or less are realized. can do. The lower limit values of Ra and Rz are not particularly limited, but in reality, each is 0.01 μm.
m, 0.05 μm.

When needle-like semiconductive fillers having a short minor axis diameter and a long major axis diameter are used as described above, the mechanical strength increase, linear expansion coefficient and hygroscopic expansion coefficient reduction effect is high, and tearing etc. It is possible to obtain a film or belt that has excellent durability and high dimensional stability, and excellent long-term transport characteristics by preventing dimensional changes due to tearing or tension.

In the present invention, it is preferable to add a needle-shaped filler to the polyimide resin composition in order not to deteriorate the surface smoothness. In addition to the needle-shaped semiconductive filler, the volume resistance value is 1 or less. × 10 ^-5 to 1 × 10 ¹⁰ Ω · cm
A conductive or semi-conductive granular or scaly filler may be added, or 1 × 10 ⁻⁵ to 1 × 10 ³ Ω · cm conductive needle-shaped filler may be added ( In the present specification, the description of the numerical value range “a to b” represents a or more and b or less, but the upper limit here is 1 × 10 ³ Ω · cm “less than”.).

Examples of the electrically conductive filler include carbon black, graphite, metal powder, electrically conductive ceramics, electrically treated inorganic substances and antistatic agents. Examples of the semiconductive filler include semiconductive inorganic materials and semiconductive ceramics.

As the carbon black, various existing carbon blacks can be used as long as they have conductivity, and there are furnace black, acetylene black, thermal black, channel black and the like.
Among them, it is one kind of furnace black, but when carbon black called Ketjen black having a large specific surface area is used, the resistance reducing effect is high even if the amount of carbon black blended is small, and yet another carbon black is used. It has been found that the voltage dependence (the property that the resistance value changes when the voltage changes and does not cause the behavior according to Ohm's law) is smaller than that in the case where it is used, and it is particularly preferable to use Ketjen black.

Examples of the metal powder include powders of copper, iron, aluminum, SUS and the like, and examples of the conductive ceramics include doped tin oxide and ITO.

Examples of the electrically conductive inorganic material include titanium oxide, metal titanate, barium sulfate, mica, and the like, which are black electrically conductive materials and tin oxide-based electrically conductive materials. Examples of the forming method include the forming method of the conductive layer shown in the needle-like semiconductive filler.

The semiconductive filler is formed by a method similar to the above conductive treatment and has a volume resistance value of 1 ×.
It may be controlled to a medium resistance value such as 10 ³ to 1 × 10 ¹⁰ Ω · cm. Further, the semiconductive ceramic compounded with the polyimide resin may be any one having a volume resistance value of 1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm, such as titanium oxide and titanium. Examples thereof include acid metal salts, aluminum borate, tin oxide, and silicon carbide. Since these fillers have a medium resistance value, they can be controlled to have a medium resistance value while maintaining high dielectric breakdown resistance after blending. In addition, the environmental dependence and voltage dependence of the resistance value can be reduced, and the number of blended parts, the dispersion state, and the variation between samples can also be reduced.

Insulating fillers can be added to the polyimide resin composition in addition to the needle-shaped semiconductive fillers. As the insulating inorganic substance, various substances such as small-diameter granular substances such as alumina and silica, plate-like and scale-like substances such as mica and clay minerals, short fiber-like substances such as calcium carbonate or whiskers-like substances are used. Insulating fillers may be added to control other properties such as elastic modulus, and also aid dispersion of conductive powder to prevent agglomeration of conductors and realize stable resistance. Sometimes you can.

The conductive filler, the semiconductive filler, and the insulating filler to be added in addition to the acicular semiconductive filler used in the present invention may have a granular shape, a acicular shape, a scaly shape or the like.

When it is granular, the particle size is 1 μm or less, preferably 0.3 μm or less, more preferably 0.1 μm or less. In the case of a molded product having a small thickness of 100 μm or less, a material having a thickness of more than 1 μm is not preferable because dielectric breakdown occurs due to local aggregation due to poor dispersion and the surface property tends to deteriorate. On the other hand, if it is 1 μm or less, even if it is a little aggregated, the insulating property and the surface roughness are not deteriorated, which is preferable. However, if the particle size is too small, the polyamic acid solution may increase in viscosity, or may be too bulky to hinder the compounding work.
It is preferably 5 μm or more. The volume resistance value is 1 × 10 ^3.
It is preferably Ω · cm or more. This is because the dielectric breakdown in the thickness direction is unlikely to occur even if some aggregates are present.

In the case of needles or scales, the minor axis diameter is 1 μm
It is preferably 0.3 μm or less, more preferably 0.1 μm or less. In a molded body having a small thickness of 100 μm or less, a material having a minor axis diameter of more than 1 μm is not preferable because dielectric breakdown is likely to occur and the surface property tends to deteriorate. On the other hand, if it is 1 μm or less, even if it is a little aggregated, the insulating property and the surface roughness are not deteriorated, which is preferable. However, if the minor axis diameter is too small, the polyamic acid solution may increase in viscosity or may be too bulky to hinder the compounding work.
It is preferably 5 μm or more.

Since the needle-like or scale-like filler is unlikely to deteriorate the insulating property and the surface roughness, unlike the case where the resistance value is granular, it is possible to widely use those having conductivity to high insulation. it can. This is because these materials tend to be oriented in the in-plane direction, so that it is difficult to form protrusions, and contact in the thickness direction due to aggregation can be suppressed. However, it is preferable that the volume resistance value is 1 × 10 ³ Ω · cm or more. This is because even if some agglomerates are present, dielectric breakdown is unlikely to occur. In addition, needle-like and scale-like particles are preferable because they easily come into contact with each other and the resistance can be controlled in the medium resistance region even if the blending amount is small. In addition, it is highly effective in increasing mechanical strength, linear expansion coefficient, and hygroscopic expansion coefficient, and prevents rupture due to tearing and dimensional change due to tension, and it has high durability and high dimensional stability. Can be obtained.

Next, the compounding amount of the filler with respect to the polyimide resin will be described.

When the needle-shaped semiconductive filler is used alone, the content of the needle-shaped semiconductive filler is 0.1 to 70 parts by weight, preferably 1 to 70 parts by weight with respect to 100 parts by weight of the polyimide resin.
60 parts by weight, more preferably 5 to 50 parts by weight.
If it is more than this number of parts, the surface roughness becomes large, which is not preferable. In addition, if it is less than this number of parts,
This is not preferable because the resistance does not decrease and a polyimide resin having a desired medium resistance value cannot be obtained.

When the needle-shaped semi-conductive filler is combined with other conductive filler, semi-conductive filler, or insulating filler, the content of the needle-shaped semi-conductive filler is 0. It may be 1 to 50 parts by weight, preferably 1 to 40 parts by weight, more preferably 5 to
30 parts by weight. It is not preferable that the amount is larger than this amount because the surface roughness after combining with other fillers becomes large. In addition, if it is less than this number of parts,
It is difficult to obtain a polyimide resin composition having a desired medium resistance value without lowering the resistance.

When the other additive is a granular conductive filler, the compounding amount is 0.1 to 100 parts by weight, preferably 1 to 75 parts by weight, more preferably 5 to 50 parts by weight, based on 100 parts by weight of the polyimide resin. Is. If the amount is more than this blending part, the surface roughness after combining with other fillers becomes large, and the voltage dependency of insulation properties and resistance deteriorates, which is not preferable. On the other hand, if the amount is less than this blending part, the resistance does not decrease and it becomes difficult to obtain a polyimide resin composition having a desired medium resistance value. However, since this filler has a low resistance, the resistance can be reduced by adding a small amount.

When the other additive is a granular semiconductive filler or insulating filler, the compounding amount is 0.1 to 150 parts by weight, preferably 1 to 125 parts by weight, based on 100 parts by weight of the polyimide resin, It is preferably 5 to 100 parts by weight. It is not preferable that the amount is larger than this amount because the surface roughness after combining with other fillers becomes large. On the other hand, if the amount is less than this blending part, the resistance does not decrease and it becomes difficult to obtain a polyimide resin composition having a desired medium resistance value. However, since the resistance of these fillers is higher than the medium resistance value, the insulating property is not deteriorated even if added in a large amount.

Further, when the other additive is a needle-shaped or scale-shaped filler, the compounding amount is polyimide resin 10
0.1 to 50 parts by weight, preferably 1 to 40 parts by weight
Parts by weight, more preferably 5 to 30 parts by weight. It is not preferable that the amount is larger than this amount because the surface roughness after combining with other fillers becomes large. Also,
When the amount is less than this blending part, the resistance is not lowered and the polyimide resin composition having the intended medium resistance value cannot be obtained, which is not preferable. However, since these fillers have a short minor axis diameter and a long major axis diameter, they are very easily oriented in the in-plane direction, and further, because they are mixed in the polyimide resin, the orientation is further advanced. As a result, the insulating property is not significantly deteriorated within the above range of the number of parts. In addition, a material having excellent surface property can be obtained.

As described above, the other additives can be blended appropriately.

By selecting a needle-shaped semiconductive filler and adding a dye and a pigment appropriately, it is possible to color a wide range from light to dark. Dyes include disperse dyes, cationic dyes, basic dyes, acid dyes, metal complex dyes, direct dyes, sulfur dyes, sulfur vat dyes, vat dyes, azoic dyes, mordant dyes, acid mordant dyes, optical brighteners. , Composite dyes, organic solvent-soluble dyes, pigment resin colors and the like. As the organic pigment, insoluble azo pigment, soluble azo pigment, phthalocyanine blue, dye lake, isoindolinone, quinacridone, dioxazine violet,
Examples include pyrinone and perylene. As the inorganic pigment, mica-like iron oxide, white lead, red lead, yellow lead, silver vermilion, ultramarine blue, navy blue, cobalt oxide, titanium dioxide, titanium dioxide coated mica, strontium chromate, titanium yellow,
Examples thereof include titanium black, zinc chromate, iron black, molybdenum red, molybdenum white, litharge, lithopone, emerald green, guinea green, cadmium yellow, cadmium red, cobalt blue, carbon black and graphite. The carbon black referred to here is not for conductivity but for coloring. The addition amount is 0.01 to 10 parts, preferably 0.1 to 5 parts, and more preferably 0.3 to 4 parts. Since the semiconductive filler can be selected from a wide range of colorless to black, it is possible to sufficiently color even a small amount of 10 parts or less. Addition of 10 parts or more is not preferable because mechanical properties and electrical properties are deteriorated. Also,
If it is less than 0.01 part, it is not preferable because it cannot be colored.

As described above, the semiconductive filler alone, the semiconductive filler and other conductive fillers are appropriately selected and adjusted within the above range, whereby high insulation can be maintained and control to a medium resistance value can be achieved. It is possible to adjust a material that has little dependence and environment dependence, and has a small number of added parts, a dispersed state, and a small variation between samples. Further, by appropriately selecting the coloring material species, it is possible to color a wide range from colorless to colored and even black. In addition, since the semiconductive filler containing a large number of functional groups such as hydroxyl groups and active oxygen on the surface has excellent dispersibility and has a strong bond with the polyimide, the mechanical strength of the unfilled product is 50% or more. A polyimide resin composition having a retention rate is easily obtained, and when a polyimide resin composed of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether is combined, the tensile elongation is 35% and the tear propagation strength is 250 g / mm. The above polyimide resin composition can be obtained. Further, even if the semiconductive filler is added, the water absorption rate can be kept at 5% or less, and the increase rate of the water absorption rate can be suppressed to not more than twice the original water absorption rate of polyimide.

In addition to the above combinations, surface treatment of the filler may be carried out depending on the purpose of forming a strong bond between the filler and the polyimide. As the surface treatment agent, a coupling agent can be used, and a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, an amino acid coupling agent, etc. can be used. When the resin is a reaction-curable linear polyimide resin, the bond becomes stronger by the surface treatment, but sufficient strength can be obtained without the treatment.

Various methods can be used to disperse the added filler or other conductive material in the polyimide resin.

When the polyimide resin is soluble in a solvent, a polyimide resin solution dissolved in the solvent and a filler preliminarily dispersed in the solvent are prepared, and both are mixed by a kneader such as a stirring blade or a three-roll to disperse the mixture. There are possible ways to proceed. On the contrary, it is also possible to add a powder or pellets of solvent-soluble polyimide to a material obtained by preliminarily dispersing the filler in a solvent and mix them well. As a method of preliminary dispersion, it is effective to add powders to a solvent and sufficiently disperse the mixture with an ultrasonic disperser. In particular, the needle-like filler may be destroyed in shape when it is subjected to excessive shearing force, so that a method not using three rolls is preferable.

When the polyimide resin is insoluble in a solvent, it is also possible to add the above-mentioned preliminary dispersion to a solution of a polyamic acid which is a precursor of polyimide, and carry out mixing and kneading in the same manner.

When the polyamic acid and the filler are mixed,
There are two main methods: First, there is a method of polymerizing a polyamic acid by adding a filler to a solvent for polymerizing the polyamic acid in advance to prepare a dispersion solution of the filler, and then adding a diamine and an acid dianhydride which are raw materials of the polyamic acid. is there. As another method, there is a method in which a dispersion solution of a filler is added to and mixed with a polyamic acid obtained by polymerization in advance. Whichever method is used, it is usually necessary to prepare a dispersion solution of the filler. Generally, the specific gravity of the filler is larger than that of the resin and is heavier. Therefore, when the filler is added to the solvent, the filler is immediately precipitated. When mixed with the polyamic acid in such a state, aggregates of the filler may be formed, and irregularities may be formed on the surface of the polyimide molded body or a portion where the resistance is locally different may be formed.

Therefore, it is preferable to add a dispersant when preparing a dispersion solution of the filler. Examples of the dispersant include metal salts and surfactants. Particularly preferred are metal salts, such as Li salt, Na salt, K salt, Rb salt and Cs.
One or a combination of two or more selected from the group consisting of salt, Be salt, Mg salt, Ca salt, Sr salt and Ba salt is preferable, and Li salt, Na salt and K salt are preferable. As the Li salt, a Li salt having a lattice energy of 1100 or less is preferable,
Specifically, LiF, LiCl, LiBr, LiI, L
Examples include iSCN and LiCF ₃ SO ₃ .
Among Na salts, Na salts having a lattice energy of 800 or less are preferable, and specifically, NaF, NaCl, NaBr, N
Examples include aI, NaSCN, NaCF ₃ SO ₃ . The K salt is preferably a K salt having a lattice energy of 800 or less, specifically, KF, KCl, KBr, K.
I, KSCN, KCF ₃ SO _{3, and the} like. Ions of these metal salts easily dissociate at room temperature,
It is preferable because the interaction with the filler becomes strong. However, if the lattice energy is too small, the effect of the addition amount becomes too large, so that one having a large lattice energy is preferable. Since these metal salts do not contain organic substances, the resin will not be burnt even during high temperature drying during molding. The dispersant may be added in a predetermined amount of 1 part by weight or less with respect to 100 parts by weight of the polyimide resin, and may be 0.01 to 0.
Even less than 1 part by weight is sufficiently effective. Generally, in the application of wire coating, the addition of a metal salt deteriorates the insulating property, and when it is added to a material having a dielectric constant of 4 or more, the ionic conductivity increases, which is not so preferable. Since polyimide is excellent in insulation and the dielectric constant is 4 or less, deterioration of insulation and voltage dependence of resistance can be reduced.

As another method for obtaining particularly good dispersibility, a filler is first added to a solvent and sufficiently dispersed by an ultrasonic disperser or the like, and a raw material of polyimide (polyamic acid) is added thereto. There is a method in which a diamine compound and an acid dianhydride compound are added to carry out a polymerization reaction. According to this method, dispersion at a micro level can be maintained satisfactorily by ultrasonic dispersion, and at the same time, stirring is always performed after the initial filler dispersion and during the polymerization, so that the dispersibility at a macro level is also achieved. Very good.

The polyimide composition having the above-mentioned composition is molded and used in various shapes. It is particularly difficult for the resistance value to be a constant level while maintaining the insulating property when the thickness is small. In that sense, the above formulation is particularly effective in a film form in a broad sense such as a film form, a sheet form, a belt form, and a tube form, particularly in a form having a thickness of 150 μm or less, preferably 100 μm or less. is there.

A typical method for molding a polyimide resin composition will be described below.

When the polyimide resin is soluble in a solution, a polyimide resin solution is prepared and processed into an arbitrary shape, and then the solvent is volatilized by heating or by using a reduced pressure in some cases to obtain a polyimide molded body. You can

A similar method can be applied at the stage of polyamic acid which is a precursor of polyimide, and this method can be applied even if the polyimide resin is not soluble in a solvent.
In this case, prior to heating, an acid anhydride such as acetic anhydride as a dehydrating agent or a tertiary amine as a catalyst can be used alone or in combination in order to accelerate imidization. However, acid anhydride can not only accelerate the imidization reaction but also cause the main chain of the polyamic acid chain to be cleaved. Therefore, due to the mechanical properties of polyimide, a combination of an acid anhydride and a tertiary amine or a tertiary amine is used. Addition of amine alone is more preferable, and a product having a higher tear propagation strength can be obtained as compared with imidization by heat only.
Specifically, the tear propagation strength is 250 g / mm or more,
More preferably, a product of 500 g / mm or more is obtained. Further, the addition of a catalyst is very preferable because it can reduce the heating time and suppress the thermal deterioration of the polyimide resin composition. In particular, a semiconductive substance may cause a change in conductivity due to heating for a long time, and therefore it is very important to shorten the heating time by adding a catalyst. Also,
In the production method by adding a catalyst, the resin is more likely to be oriented in the in-plane direction, and when acicular or scale-like tin oxide is used together, the filler is easily oriented in a plane. as a result,
The filler oriented in the thickness direction can be reduced, the electric insulation can be improved, and the portion where the electrical characteristics are deteriorated in the thickness direction due to moisture absorption of the filler can be reduced. And it is preferable because the humidity dependency of resistance can be reduced. Further, the molding time is short, the productivity is drastically increased, the strength is easily produced during the production, and the brittleness during the production can be prevented.
These advantages of the manufacturing method by adding a catalyst are that the thickness is 100μ.
This is particularly noticeable in the case of a thin polyimide molding of m or less.

The following method is mentioned as an example of a specific method for forming a film and a tubular article.

The polyamide or polyimide resin solution in which the above inorganic fillers are dispersed is applied onto the endless belt after controlling the thickness by using a T-die, a comma coater, a doctor blade or the like. The resin solution is heated and dried by hot air or the like until it has self-supporting property, and then peeled off from the endless belt. A film-like molded product can be obtained by fixing both ends of the peeled-off semi-dried film with a pin or a clip, and sequentially passing them through a high-temperature heating furnace while controlling the length in the width direction. Alternatively, it is applied in the same manner on a continuous sheet-shaped support such as metal, and a film or sheet-shaped polyimide molded body fixed in a sheet is obtained by passing this through a heating furnace, and then supporting. A method of peeling off from the body sheet or removing the support sheet by means such as etching may be adopted. The easiest method is to obtain a tubular body such as a belt or a tube by cutting the thus obtained film- or sheet-like molded body into a predetermined length and width and connecting them. An adhesive, an adhesive tape, or the like can be used for the joining, but this method inevitably causes a step or a break at the joint, which may cause inconvenience depending on the application.

As a method for obtaining a tubular product, a resin solution of polyamide or polyimide is applied to the inner surface or the outer surface of a cylindrical mold, the solvent is volatilized by heating or drying under reduced pressure, and this is heated to the final firing temperature as it is. Alternatively, it may be peeled off once, fitted into the outer periphery of another mold for finally defining the inner diameter, and heated to the final firing temperature. In applying the resin solution to the cylindrical mold, it is also effective to rotate the mold in order to reduce the variation in thickness due to the sagging of the resin solution. The final firing temperature needs to be appropriately selected depending on the structure of the polyimide and the heat resistance of carbon to be added, but when heating and firing from a polyamic acid state with a non-thermoplastic polyimide, the temperature is generally between 350 ° C and 450 ° C. In the case of plastic polyimide, the glass transition temperature of polyimide is -10
A suitable range is between 0 ° C and -20 ° C.

When the polyimide molded article of the present invention is used as a member of an electrophotographic apparatus, the outermost layer of a fluororesin whose conductivity is controlled is provided on the surface in order to improve the toner releasability, transferability and toner cleaning property. Should be formed.
Examples of the fluororesin include PTFE and PFA, and examples of the additive for controlling conductivity include those listed as the additive for controlling conductivity of polyimide.
As a method for forming the outermost layer, coating, laminating films, etc. can be considered, but a method in which these materials are spray-coated as a dispersion is general.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0099]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples.

The shape of the filler used in each example,
The description of the minor axis diameter and major axis diameter is based on the manufacturer's values obtained from product catalogs.

(Physical Property Evaluation Method) Next, the physical property evaluation method of the polyimide resin composition and the polyimide molded article will be described. The physical properties were measured by molding a polyimide film made of a resin composition or a tubular material and cutting out a film sample.

Surface roughness Ra, Rz of the film sample
Was measured as follows. As a measuring instrument, a surface roughness measuring instrument Surftest 402 (Mitutoyo Corporation) was used, and a measurement sample cut into a size of length 20 mm × width 20 mm was used. The measurement surface was the surface that was in contact with the metal surface when the varnish (resin solution) was cast. The measurement range was 2.5 mm and the feed rate was 0.1 mm / s.

The film sample and the filler are digital ultra-high resistance / micro ammeter R manufactured by Advantest Corporation.
100 using HR probe manufactured by Mitsubishi Chemical Corporation and 8340
The volume resistance value and the surface resistance value at V were measured. The measurement environment was performed in the following three ways, and the measurement was performed in each environment. The film sample was also measured at 1000V. The measurement sample is 1 for film sample
The material cut into 0 cm × 10 cm was used, and the inorganic filler used was compressed into 10 cm × 10 cm × 0.5 mm. After leaving for 24 hours in an environment (LL) with a temperature of 10 ° C and a humidity of 15% Rh, a temperature of 23 ° C and a humidity of 55% R
After being left for 24 hours in an environment (NN) of h, after being left for 24 hours in an environment (HH) of a temperature of 30 ° C. and a humidity of 80% Rh, the resistance value is NN unless otherwise specified.
Refers to the results measured in.

The environmental dependence of the resistance value means the ratio (Rl / R) of the resistance value Rl at low temperature and low humidity to the volume resistance value Rh at high temperature and high humidity.
The value of h) and the voltage dependence of the resistance value are the volume resistance value R when _{100 V} is applied and the volume resistance value R when 1000 _V is applied.
_It means the value of the ratio of _1000V ( _R100V / _R1000V ). When these values are in the range of 0.3 to 30, the material has little dependence (small), and when these values are in the range of 0.01 to 0.3 or 30 to 100, the material having medium dependence ( During),
When the ratio is 0.01 or less or 100 or more, the material has large dependency (large).

The insulation property of the film sample in the thickness direction was measured as follows. This film has a temperature of 23
Leave for 24 hours in an environment (NN) where the temperature and humidity are 55% Rh,
Under the environment, the insulation property was measured by a YSS type electric breakdown resistance tester manufactured by Yasuda Seiki. Dielectric breakdown voltage is 15kV
/ Mm or higher material with high insulation (high), 10 kV
/ Mm or more is a material with medium insulation (medium), 10
A material having a low insulating property (low) was used as a material having a kV / mm or less.

The tensile elastic modulus and tensile elongation of the film sample were measured according to ASTM D882.
The tear propagation strength of the film sample is measured by ASTM
It carried out based on D1938.

The black density of the film sample was evaluated by a Macbeth reflection densitometer (Macbeth RD914).

Next, examples and comparative examples will be described.

Example 1 As aromatic diamine 4,
DMF solution of polyamic acid obtained by using 4'-diaminodiphenyl ether and pyromellitic dianhydride as aromatic tetracarboxylic dianhydride (solid content concentration 1
75 g of 8.5% and a solution viscosity of 3,000 poise) was prepared. On the other hand, acicular titanic acid potassium salt as a semiconductive filler (Tismo D: Otsuka Chemical Co., Ltd .: specific gravity 3.3 g)
/ Cm ³ , volume resistance value 1.0 × 10 ⁷ Ω · cm, minor axis diameter 0.45 μm, major axis diameter 15 μm, ion elution amount 500-
5.08 g of 10000 ppm) was collected, and this was dispersed in DMF 8 times the weight of the filler to prepare a filler dispersion solution.

Then, a filler dispersion was added to the above polyamic acid solution and kneaded. Obtained varnish (resin solution)
Was cast into a tubular film, acetic anhydride / isoquinoline / DMF was added in an amount of 9.03 g / 11.4 g / 15.6.
The solution consisting of g is added and mixed, and then cast on an aluminum foil, 140 ° C / 600 seconds, 275 ° C / 40 seconds, 40
Heat treatment was performed at 0 ° C. for 93 seconds to obtain a polyimide film having a thickness of about 75 μm. The amount of filler in the tubular product is 30 parts by weight based on 100 parts by weight of polyimide solid content. The characteristic values are shown in Tables 1 and 2. When it is obtained as a tubular product, it can be prepared by applying it to the inner surface or the outer surface of a metal cylinder having a mirror surface instead of the aluminum foil. Physical properties such as electrical properties and mechanical properties of the tubular product may be considered to be the same as those of the film. 1 peeling of polyimide from aluminum foil and metal tube
It was carried out after heating at 40 ° C.

The polyimide film alone (excluding filler) polymerized by the same method as described above has a coefficient of linear expansion of 21 ppm, a coefficient of hygroscopic expansion of 16 ppm, a tensile elastic modulus of 2.9 GPa and an elongation of 70%. The tear propagation strength was 450 g / mm and the water absorption was 2.5%.

(Examples 2 to 19) Example 1 was repeated except that the inorganic filler (all needles) and other additives were blended in the blending ratio shown in Table 1 in place of the needle-shaped potassium titanate salt.
A polyimide film was obtained in the same manner as. The characteristic values are shown in Tables 1 and 2.

Details of the fillers described in Examples 2 to 19 of Table 1 are as follows. Carbon-coated potassium titanate refers to BK400HR manufactured by Otsuka Chemical Co., Ltd., and the core material is the acicular potassium titanate salt used in Example 1. Conductive carbon coated mica and semi-conductive carbon coated mica are BK400M and BK400M manufactured by Otsuka Chemical Co., Ltd.
It refers to a medium resistance product.

The tin oxide-based aluminum borate and the semi-conductive tin oxide-based barium sulfate are Pastran-TYPEV-KK006 and Pastran 4350 manufactured by Mitsui Kinzoku Co., Ltd.
Refers to.

The conductive tin oxide-based granular titanium oxide and the conductive tin oxide-based acicular titanium oxide are E manufactured by Ishihara Sangyo Co., Ltd.
Refers to T300W and FT3000.

Carbon black refers to 3030B manufactured by Mitsubishi Chemical Corporation.

The ion elution amount of potassium titanate was 50.
0 to 10000 ppm, <50 of other fillers
It is ppm.

Example 20 As aromatic diamine 4,
D'of the polyamic acid polymerized by dissolving 3 equivalents of 4'-diaminodiphenyl ether in DMF, then adding 4 equivalents of PMDA, and further adding 1 equivalent of paraphenylenediamine.
MF solution (solid content concentration 18.5%, solution viscosity 3,000
A polyimide film was obtained in the same manner as in Example 8 except that poise) was used. The characteristic values are shown in Tables 1 and 2.

The polyimide film thus polymerized has a linear expansion coefficient of 8 ppm and a hygroscopic expansion coefficient of 9 pp.
m, tensile elastic modulus was 4 GPa, elongation was 70%, tear propagation strength was 450 g / mm, and water absorption was 2.1%.

Example 21 As an aromatic diamine 4,
1 equivalent of 4'-diaminodiphenyl ether and 1 equivalent of paraphenylenediamine were dissolved in DMF, and then TMHQ1
A polyimide film was obtained in the same manner as in Example 8 except that a DMF solution of polyamic acid polymerized by adding 1 equivalent of PMDA was added (solids concentration 18.5%, solution viscosity 3,000 poise). Characteristic values are shown in Table 1 and Table 2
Shown in.

The polyimide film thus polymerized alone has a linear expansion coefficient of 9 ppm and a hygroscopic expansion coefficient of 5 pp.
m, tensile elastic modulus was 6 GPa, elongation was 30%, tear propagation strength was 450 g / mm, and water absorption was 1.2%.

Examples 1 to 21 obtained as described above
The surface roughness of the polyimide film of Ra was 0.5 μm or less and Rz was 2.5 μm or less, which was very excellent in surface properties, and was excellent in scraping off the toner with a blade. Further, the residual volatilization of the gel film at the time of peeling from the aluminum foil or the metal cylinder was 20% or less, and the surface of the aluminum foil or the metal cylinder was transferred, and thus the surface property was very excellent.

The volume resistance value at NN is 1 × 10 ⁹ to
The resistance was adjusted to a medium resistance region of 1 × 10 ¹³ Ω · cm, and the insulation was excellent at 10 kV / mm or more.

The ratio of the volume resistance values of LL and HH is 100.
It was less than twice, and the environmental dependence of the volume resistance value was small.
Further, the ratio of the volume resistance values measured at 100 V and 1000 V was 100 times or less, and the voltage dependency of the volume resistance value was small. Further, as a result of measuring the volume resistance value at 100V for five samples produced by the same operation as described above, the difference between the maximum value and the minimum value was 3 times or less, and the variation between the samples was also very small. The variation within the same sample was three times or less, which was very small.

In Examples 1 to 7, the ratio of the volume resistance values due to the difference in the number of added parts (5 parts) of the needle-shaped semiconductive filler was 3 times or less, and the dependency of the volume resistance value on the number of added parts was small. .

Further, Examples 3 to 9, 12, 14 to 15,
Regarding Nos. 18 and 20 to 21, since only a semiconductive filler was included as a filler, the environmental dependency of the resistance value and the voltage dependency were 30 times or less, and the insulating property was 15 kV or more, showing extremely excellent electrical characteristics. .

The tensile modulus of the film was superior to that of the non-filled product, and the elongation was 50% or more and the tear propagation strength was 50% or more, indicating the retention rate. In addition, granular, scale-like,
The tensile strength, elongation, and tear propagation strength tended to increase in the order of needles.

Further, the linear expansion coefficient and the hygroscopic expansion coefficient were several ppm lower than those of the product with no filler added.

The tensile modulus increased in the order of Example 8, Example 20, and Example 21. It is speculated that this is because the tensile elastic modulus of the base resin increases in this order.

(Examples 22 to 41) In addition to the compounds of Examples 3 to 21, coloring carbon black (MA200R) was used.
B: Example 3 except that 4 parts of Mitsubishi Chemical Corporation was added.
A polyimide film was obtained in the same manner as described above.

The black densities of the films obtained in Examples 3 to 21 were 1 or more, showing excellent blackness. It was also found that the physical properties such as electric properties and mechanical properties were almost the same as those in Examples 3 to 21, and the electric properties and mechanical properties were not significantly impaired.

(Comparative Example 1) Needle-shaped titanium oxide coated with conductive tin oxide on 21 g of DMF (FT3000: Ishihara Sangyo Co., Ltd.):
Specific gravity 4.4 g / cm ³ , volume resistance value 1.0 × 10 ³ Ω · c
(less than m) except that a liquid in which 2.78 g is dispersed is prepared,
A polyimide tubular product was obtained in the same manner as in Example 1. The amount of filler in the tubular product was 20 parts based on 100 parts by weight of polyimide solid content. The characteristic values are shown in Tables 1 and 2.

Comparative Example 2 DMF 21 g was mixed with carbon black (# 3030B: Mitsubishi Chemical Corporation: <1.0E + 1).
A polyimide tubular product was obtained in the same manner as in Example 1 except that a liquid in which 4.17 g of Ω · cm) was dispersed was prepared. The amount of filler in this tubular product was 30 parts based on 100 parts by weight of polyimide solid content. The characteristic values are shown in Tables 1 and 2.

The volume resistance value of NN in the polyimide resins of Comparative Examples 1 and 2 obtained as described above was adjusted to the target medium resistance region, but HH had a very low resistance value. Further, the ratio of the volume resistance values due to the difference in the number of added parts of the filler (5 parts) was 3 times or more, and the dependency of the volume resistance value on the number of added parts was large. Further, the ratio of the volume resistance values of LL and HH was 1000 times or more, and the environment dependency of the volume resistance value was very large. Moreover, the ratio of the volume resistance values measured at 100 V and 1000 V was 100 times or more, and the voltage dependency of the volume resistance value was large. In addition, as a result of measuring the volume resistance value at 500 V with respect to 5 samples prepared by the same operation as described above, the difference between the maximum value and the minimum value was 3 times or more, and the variation among the samples was very large. The variation within the same sample was three times or more, which was very large.

Further, the same formulation as in this comparative example was used, but not chemical curing but thermal curing (150 ° C., 30 minutes, 20 minutes).
0 ℃ ・ 30 minutes, 300 ℃ ・ 30 minutes, 400 ℃ ・ 30 minutes)
The film prepared in 1 above was extremely brittle both during and after molding, and required a very long molding time as compared with chemical curing.

[0136]

[Table 1]

[0137]

[Table 2]

[0138]

As described in detail above, the polyimide molded article of the present invention has good insulating properties, a medium resistance value, small variation between samples due to variation in the number of added parts, small surface roughness, and resistance. There is little environmental dependence and voltage dependence of the value,
It has excellent mechanical properties and is particularly suitable for applications such as transfer belts in electrophotographic devices.

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Claims (12)

[Claims] 1. A volume resistance value of 1 × 10 ³ to 1 × 10 ¹⁰ Ω.
・ Volume resistance value containing 1 cm of inorganic filler is 1 × 10
^The polyimide resin composition is ⁶ to 1 × 10 ¹³ Ω · cm and has a center line average roughness Ra of 0.01 μm or more and 0.5 or more.
μm or less, ten-point average roughness Rz is 0.05 μm or more and 2.5
A polyimide molded body having a thickness of not more than μm. 2. The inorganic filler has a minor axis diameter of 0.05.
μm or more and 1 μm or less, major axis diameter is 7.5 μm or more and 100 μm
The polyimide molded body according to claim 1, which is a needle-shaped filler having a size of m or less, and its content is 0.1 to 70 parts by weight with respect to 100 parts by weight of the polyimide resin. 3. The volume resistance value of the inorganic filler is 1 × 1.
The polyimide molded body according to claim 1 or 2, which has a resistivity of 0 ³ to 1 × 10 ⁸ Ω · cm. 4. The polyimide resin composition has a particle size of 0.005 μm or more and 1.0 μm in addition to the acicular filler.
The following contains a granular inorganic filler having a volume resistance value of 1 × 10 ⁻⁵ to 1 × 10 ¹⁰ Ω · cm, and the content thereof is 0.01 to 150 parts by weight with respect to 100 parts by weight of the polyimide resin. The polyimide molded body according to any one of claims 2 to 3. 5. The needle-shaped polyimide resin composition
In addition to the filler, the minor axis diameter is 0.005 μm or more and 1.0 μ
Volume resistance of 1 x 10 or less^-Five~ 1 x 10 ^TenΩ · cm
It contains a scale-like inorganic filler whose content is poly
0.01 to 50 parts by weight based on 100 parts by weight of imide resin
The polyimid according to any one of claims 2 to 4, which is
Molded body. 6. The needle-shaped polyimide resin composition
In addition to the filler, the minor axis diameter is 0.005 μm or more and 1.0 μ
Volume resistance of 1 x 10 or less^-Five~ 1 x 10 ³(1 x 1
0^-Five1 x 10 or more³Less than) Ω · cm needle-like inorganic fiber
Including the filler, the content of which is 100% by weight of polyimide resin
2 to 5, which is 0.01 to 50 parts by weight with respect to parts.
The polyimide molded body according to any one of 1. 7. The polyimide molded body according to claim 1, wherein the polyimide resin is a reaction-curable linear polyimide resin. 8. The polyimide resin according to claim 1, wherein the polyimide resin is a polyimide resin obtained by adding an acid anhydride and / or a tertiary amine as an imidization promoter to a polyamic acid and then heating and baking the mixture. Polyimide molding. 9. The polyimide molded body according to claim 1, which is in the form of a film. 10. The polyimide molded body according to any one of claims 1 to 8, which has a tubular shape. 11. The film-shaped or tubular polyimide molded article according to claim 9 or 10, wherein the thickness is 10 or less.
A polyimide molded body having a size of not less than 100 μm and not more than 100 μm. 12. The polyimide molded body according to claim 1, which is used for transfer, intermediate transfer, transfer fixing, or fixing of an electrophotographic apparatus.