JP2001323164A - Curable composition for roller and rubber roller made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable composition that can give a molding roller free from appearance defects such as surface blisters and pinholes, which composition comprises an addition-type curable composition comprising an alkenyl- containing oxyalkylene polymer, a hydrosilyl-containing compound, a hydrosilylation catalyst, and an oxyalkylene polymer having only one alkenyl group in the molecule. SOLUTION: Provided is a curable composition essentially consisting of (A) a polymer having at least two alkenyl groups in the molecule, having a main chain comprising repeating units mainly consisting of oxyalkylene units, and having a number-average molecular weight of at least 4,000, (B) a compound having at least too hydrosilyl groups in the molecule, (C) a hydrosilylation catalyst, (D) a conductivity improver, and (E) a polymer having at least one alkenyl group on a terminal, having a main chain comprising repeating units comprising oxyalkylene units, having no active hydrogen in the molecule, and having a number-average molecular weight of at most 3,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
Laser printer, facsimile, composite OA of these
The present invention relates to a curable composition constituting a rubber elastic layer in an electrophotographic roller incorporated in an electrophotographic image forming apparatus such as an apparatus, and a rubber roller therefrom.

[0002]

2. Description of the Related Art Generally, such an electrophotographic roller as described above has a rubber elastic layer formed of a curable composition around a conductive core such as a metal shaft. As the curable composition constituting the rubber elastic layer of the roller, a polymer composed of an oxyalkylene unit containing an alkenyl group, a compound containing a hydrosilyl group, and an addition-type curable composition obtained from a hydrosilylation catalyst include: It is known that a curable composition suitable for a roller material can be obtained by adding a conductivity-imparting agent such as carbon black to the curable composition.

[0003] Among the above-mentioned electrophotographic rollers, as for the roller used in a portion which comes into contact with other rollers or members, the curable composition for the roller constituting the rubber elastic layer has a low hardness. In addition, characteristics such as no bleeding compound and small compression set are required. A method for solving such a problem has already been proposed (JP-A-09-124752, etc.). In this method, the curable composition contains a compound having only one functional group capable of reacting with the curable component in the curable composition. However, the above-mentioned method has a large problem of foaming of the roller surface and poor appearance such as pinholes.

[0004]

SUMMARY OF THE INVENTION In view of the above, the present invention relates to an electrophotographic roller incorporated in an image forming apparatus utilizing an electrophotographic method, wherein a roller at a portion which comes into contact with another roller or member is provided. Foaming on the roller surface when used for
An object of the present invention is to provide a curable composition for a roller which clarifies the cause of poor appearance such as a pinhole and solves the problem, and a rubber roller therefrom.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and found that the appearance of defects such as foaming on the roller surface and pinholes was caused by hydrogen generated by active hydrogen. The present inventors have found out that there has been the present invention. That is, the present invention provides: (A) having at least one alkenyl group in a molecule;
(B) a polymer having at least two hydrosilyl groups in the molecule (C) a hydrosilylation catalyst (D) conductivity imparting Agent (E) A polymer having at least one alkenyl group at the terminal and having a number average molecular weight of 3,000 or less in which the repeating unit of the main chain mainly comprises oxyalkylene units and having no active hydrogen in the molecule. A curable composition for a roller comprising the components (A) to (E) as essential components, and a rubber roller provided with at least one rubber elastic layer made of the curable composition for a roller around a conductive shaft. .

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The roller of the present invention is a roller used in an electrophotographic copying machine, a laser printer, and the like.
It is used for a portion that comes into contact with another roller (including a photosensitive drum) or a member (for example, a blade).

[0007] The curable composition used in the production of rollers used in these applications is a curable composition for rollers that is converted from a liquid resin composition to a rubbery solid by a reaction, and has a low hardness and bleeds. A curable composition for a roller, which is characterized by containing no compound and having a small compression set, has been reported (JP-A-09-124).
No. 752). The curability for rollers is a compound having only one functional group capable of reacting with the curable component in the curable composition, specifically, having only one alkenyl group in the molecule and repeating the main chain. It is to contain a polymer whose unit is an oxyalkylene unit.

However, when the oxyalkylene polymer having only one alkenyl group described in the above-mentioned patent is used, foaming, pinholes and the like appear on the roller surface during roller molding, and other rollers and members are not used. This has been a particular problem with rollers that are used in areas that come into contact with the roller. It is considered that these are caused by the fact that, as a side reaction of the hydrosilylation reaction, active hydrogen at the terminal of the oxyalkylene polymer having only one alkenyl group reacts with the hydrosilyl group to generate hydrogen. It is considered that hydrogen generation at this time requires a compound or polymer having a hydrosilyl group and a hydrosilylation catalyst.

Therefore, it is important that the compound having a functional group capable of reacting with the curable component in the curable composition does not have active hydrogen, and (A) at least two alkenyl groups in the molecule. Have
(B) a polymer having at least two hydrosilyl groups in the molecule (C) a hydrosilylation catalyst (D) conductivity imparting Agent (E) A polymer having a number average molecular weight of 3,000 or less, having at least one alkenyl group at a terminal and having an oxyalkylene unit as a repeating unit in the main chain and having no active hydrogen in the molecule. The above problem can be solved by using the curable composition for a roller of the present invention containing the above components (A) to (E) as essential components.

The component (A) in the curable composition of the present invention refers to a polymer comprising 50% or more, preferably 70% or more of oxyalkylene units in the units constituting the main chain. As the unit contained other than the above, a compound having two or more active hydrogens, such as ethylene glycol, a bisphenol compound, glycerin, trimethylolpropane, pentaerythritol, etc. Units. The oxyalkylene unit does not need to be one kind, and may be a copolymer (including a graft polymer) composed of ethylene oxide, propylene oxide, butylene oxide, or the like.

The molecular weight of the polyoxyalkylene polymer as the component (A) is preferably a number average molecular weight (Mn) from the viewpoint of improving the balance between reactivity and hardness reduction.
4,000-50,000, and 4,000-3
Preferably it is 000. In particular, those having a number average molecular weight of 5,000 or more, and more preferably 5,000 to 10,000.
Those which are 0 are preferred. When the number average molecular weight is less than 4,000, it becomes difficult to obtain sufficient mechanical properties (rubber hardness, elongation) and the like when the curable composition is cured. On the other hand, if the number average molecular weight is too large,
Since the molecular weight per alkenyl group contained in the molecule increases or the reactivity decreases due to steric hindrance, curing is often insufficient, and the viscosity becomes too high, resulting in poor processability. It tends to be worse.

When used as a curable composition for an electrophotographic roller, it is preferable to use oxypropylene, oxybutylene or the like whose main chain skeleton has relatively low water absorption in terms of environmental stability of electric characteristics. In particular, the main chain skeleton is preferably oxypropylene.

The alkenyl group contained in the oxyalkylene polymer is not particularly limited as long as it is a group containing a carbon-carbon double bond which is active in a hydrosilylation reaction. Examples of the alkenyl group include an aliphatic unsaturated hydrocarbon group such as a vinyl group, an allyl group, a methylvinyl group, a propenyl group, a butenyl group, a pentenyl group, and a hexenyl group, a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group. And the like, a cyclic unsaturated hydrocarbon group, a methacryl group and the like.

One of the characteristics of the curable composition is that
It is easy to set the rubber-like elastic body obtained after curing to low hardness, and in order to exhibit this characteristic, the number of alkenyl groups of the component (A) is preferably 2 or more at the molecular terminal,
If the number of alkenyl groups is too large compared to the molecular weight of the component (A), the composition becomes rigid and it is difficult to obtain good rubber elasticity.

Next, as the component (B) in the curable composition particles, polyorganohydrogensiloxane is mentioned as one of preferred ones. The term "polyorganohydrogensiloxane" as used herein refers to a siloxane compound having a hydrocarbon group or a hydrogen atom on a silicon atom. To show the structure specifically,

Embedded image Or two or more of these units, such as a chain or a ring represented by

Embedded image And the like.

In using these components (B), those having good compatibility with the components (A), (C), (D) and (E) or having good dispersion stability in the system are preferred. . Especially when the viscosity of the whole system is low,
When a component having low compatibility with the above components is used as the component (B), phase separation may occur and poor curing may be caused. Further, a filler having a small particle size such as fine powder silica may be blended as a dispersing aid. (A) component,
If the compatibility with the component (C), the component (D) and the component (E) or the dispersion stability is specifically shown as being relatively good,

Embedded image And the like.

The amount of the component (B) used in the curable composition of the present invention is based on the total amount of the alkenyl groups of the components (A) and (E) and the silicon-bonded hydrogen of the component (B). It is preferable to use 0.5 to 3.0 equivalents of atoms. When the silicon-bonded hydrogen atom of the component (B) is less than 0.5 equivalent to the total amount of the alkenyl groups of the components (A) and (E), crosslinking may be insufficient. If it exceeds 3.0 equivalents, there is a problem that physical properties are greatly changed due to the influence of silicon-bonded hydrogen atoms remaining after curing. In particular, when it is desired to suppress this effect, it is preferable to use the component (B) in an amount of 0.7 to 1.5 equivalents.

The hydrosilylation catalyst as the component (C) in the curable composition of the present invention is not particularly limited, and any catalyst can be used. Specifically, solid platinum is supported on a carrier such as chloroplatinic acid, platinum alone, alumina, silica, and carbon black; a platinum-vinylsiloxane complex {for example, Pt _n (ViMe ₂ SiOSiM)
e ₂ Vi) n, Pt [(MeViSiO) _{4] m};} platinum - phosphine complex {for _{example, Pt (PPh 3) 4,} Pt
(PBu ₃ ) ₄ }; Platinum-phosphite complex {for example, P
t [P (OPh) ₃ ] ₄ , Pt [P (OBu) ₃ ] ₄ } (where Me is a methyl group, Bu is a butyl group, Vi is a vinyl group, Ph is a phenyl group, and n and m are Represents an integer),
Pt (acac) ₂ , and also the platinum-hydrocarbon complexes described in Ashby et al., U.S. Pat. Nos. 3,159,601 and 3,159,662; and Lamoreaux.
No. 3,220,972 to the platinum alcoholate catalyst.

Examples of catalysts other than platinum compounds include
Is RhCl (PPh_Three)_Three, RhCl _Three, Rh / Al
_TwoO_Three, RuCl_Three, IrCl_Three, FeCl_Three, AlCl_Three,
PdCl_Two・ 2H_TwoO, NiCl_Two, TiCl_Four, Etc.
Can be These catalysts may be used alone or in combination of two or more.
It may be used together. From the viewpoint of catalytic activity, chloroplatinic acid,
Platinum-olefin complex, platinum-vinylsiloxane complex,
Pt (acac)_TwoAre preferred. Especially for the amount of catalyst
There is no limitation, but 1 mol of alkenyl group in component (A)
10 for^-1-10^-8It is good to use in the range of mol.
Preferably 10^-2-10^-6Use in the range of mol
No. Also, hydrosilylation catalysts are generally expensive and corrosive.
In addition, a large amount of hydrogen gas is generated and the cured product foams
10^-1If you do not use more than mol
Is good.

The conductivity-imparting agent, which is the component (D) in the curable composition, is a component that imparts the above-described curable composition with conductivity required for a roller used in an electrophotographic system. Examples of the conductivity-imparting agent of the component (D) include carbon black, metal fine powder, and organic compounds having a quaternary ammonium base, a carboxylic acid group, a sulfonic acid group, a sulfate group, a phosphate group, and the like. Or a polymer,
A compound having a conductive unit represented by ether ester amide or ether imide polymer, ethylene oxide-epihalohydrin copolymer, methoxy polyethylene glycol acrylate, or a compound having a conductive unit, or an antistatic agent such as a high molecular compound can impart conductivity. And the like. These conductivity imparting agents may be used alone or in combination of two or more.

The added amount of the conductivity-imparting agent as the component (D) is 3 to the total amount of the components (A) to (C) and (E).
It is preferable that the amount is not more than 0 parts by weight because the rubber hardness is not increased. On the other hand, from the viewpoint of obtaining a uniform resistance, the amount is preferably 5 parts by weight or more, and the amount added may be determined from the balance of physical properties so that the cured product has the required rubber hardness and volume resistivity. Note that, depending on the type or the amount of the conductivity-imparting agent used, the hydrosilylation reaction may be inhibited. Therefore, the effect of the conductivity-imparting agent on the hydrosilylation reaction must be considered.

The component (E) in the curable composition of the present invention comprises:
It is essential to have no active hydrogen. Specific examples of the polymer constituting the main chain include polyethylene oxide,
Examples include polypropylene oxide, polybutylene oxide, ethylene oxide, propylene oxide, and two or more random or block copolymers of butylene oxide. In the case of the polymer of the component (E), oxypropylene, oxybutylene or the like whose main chain skeleton is relatively low in water absorption is used in the environmental stability of electric characteristics, similarly to the polymer of the component (A). It is particularly preferable that the main chain skeleton is oxypropylene.

The component (E) is preferably represented by the following formula (1) and having an alkenyl group at one end and an alkyl or aryl group at the other end. R ₁ —O—X—O—R ₂ (1) (R ₁ : alkenyl group, R ₂ : alkyl group or aryl group, X: number average molecular weight 3, in which the main chain repeating unit mainly comprises oxyalkylene unit, 000 or less polymer)

Specific examples of the terminal alkenyl group in the above general formula (1) include aliphatic unsaturated hydrocarbon groups such as vinyl group, allyl group, methylvinyl group, propenyl group, butenyl group, pentenyl group and hexenyl group. And a cyclic unsaturated hydrocarbon group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, and a methacryl group.

Specific examples of the alkyl group in the general formula (1) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl, a tert-butyl, a pentyl group, Isopentyl group,
Neopentyl group, tert-pentyl group, hexyl group,
Examples include cyclic saturated hydrocarbon groups such as an isohexyl group and a cyclohexanyl group. Further, specific examples of the aryl group in the general formula (1) include a phenyl group, a tolyl group, a mesityl group, a xylyl group, a cumenyl group, a naphthyl group, a benzyl group, a benzhydryl group, a phenethyl group, a trityl group, and the like. Can be

The number average molecular weight of the component (E), which is a polymer having the above structure, is preferably smaller than the number average molecular weight of the polymer of the component (A). When the number average molecular weight of the component (E) is larger than that of the component (A), the rubber hardness becomes too low, and a desired rubber hardness cannot be obtained. The component (E) has a number average molecular weight of from 100 to 3,000 from the viewpoint of effectively improving the balance of physical properties such as low hardness, no bleeding compound, and low compression set.
0, particularly preferably 200 to 1,000.

Further, the blending amount of the component (E) is (A)
0.1 to 15 parts by weight, more preferably 0.1 to 10 parts by weight, particularly preferably 0.5 to 5 parts by weight, per 100 parts by weight of the components.

Further, a storage stability improver can be used in the curable composition of the present invention for the purpose of improving storage stability. The storage stability improver is a usual stabilizer known as a storage stabilizer for the component (B) of the present invention, and may be any as long as it achieves the intended purpose, and is particularly limited. is not. Specifically, a compound containing an aliphatic unsaturated bond, an organic phosphorus compound, an organic sulfur compound, a nitrogen-containing compound, a tin compound, an organic peroxide, or the like can be preferably used. More specifically, 2-benzothiazolyl sulfide, benzothiazole, thiazole, dimethylacetylene dicarboxylate, diethylacetylene dicarboxylate, butylhydroxytoluene, butylhydroxyanisole, vitamin E, 2- (4-morphodinyl Dithio) benzothiazole, 3-methyl-1-buten-3-ol, organosiloxane containing an acetylenically unsaturated group, organosiloxane containing an ethylenically unsaturated group, acetylene alcohol, 3
-Methyl-1-butyl-3-ol, diallyl fumarate, diallyl maleate, diethyl fumarate, diethyl maleate, dimethyl maleate, 2-pentenenitrile, 2,3-dichloropropene, and the like. It is not limited.

The curable composition of the present invention contains various fillers, various functionalizing agents, antioxidants, ultraviolet absorbers,
A pigment, a surfactant, a solvent, and a silicon compound may be appropriately added. Specific examples of the filler, silica fine powder,
Examples include calcium carbonate, clay, talc, titanium oxide, zinc white, diatomaceous earth, and barium sulfate.

The curable composition of the present invention containing the above-mentioned components (A) to (E) as essential components and further adding the above-mentioned other components used as necessary, for example, in the center of SU
Casting, injection, extrusion, etc. into a mold equipped with a conductive shaft made of a metal shaft such as S
° C, preferably at a temperature of 100 to 140 ° C for 10 seconds to
By heating and curing for one hour, preferably for about one to forty minutes, it can be formed into various rollers used in electronic copiers or printers. In this case, post-curing may be performed after semi-curing.

The roller thus formed is:
The use of the component (E) reduces the hardness of the cured product, reduces the permanent compression strain, and reduces bleed. In addition, the component (E) has no active hydrogen, so that the component (E) has no active hydrogen. This solves the problem of poor appearance such as foaming and pinholes.

[0032]

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

The rollers according to Example 1 and Comparative Example 1 are constituted by providing a conductive elastic layer (rubber elastic layer) having a thickness of about 4 mm around a SUS shaft having a diameter of 8 mm. . Hereinafter, a specific configuration of the conductive elastic layer will be described.

(Example 1) First, as the component (A), AC
100 g of X004 (manufactured by Kanegafuchi Chemical), 10 g of MA220 (manufactured by Mitsubishi Chemical) as a component (D) and UNIOX PKA50006 (manufactured by NOF Corporation) as a component (E)
3 g of main chain skeleton: oxyethylene, terminal functional groups: allyl group and methoxy group, number average molecular weight: 350) were kneaded with a roll three times. Then, as a component (B), a compound B having the following structure is added to this mixture.

Embedded image And 6.6 g of bis (1,3-divinyl-1,1,3,3-tetramethyldisiloxane) as the component (C).
70 μL of a platinum complex catalyst (17.9 × 10 ⁻⁵ mmol / μL, xylene solution) and 35 μL of dimethyl maleate as a storage stability improver were weighed and uniformly mixed. The composition is subjected to a vacuum defoaming stirrer (C-Tech Co., Ltd.) for 60 hours.
Degassed for a minute. This composition was coated around the shaft, and allowed to stand for 25 minutes in an environment of 140 ° C. in a mold and cured to form an elastic layer having a thickness of about 4 mm. As a result of observing the foaming and pinholes on the roller surface, no foaming and pinholes were found on the roller surface.

(Comparative Example 1) With respect to the formulation described in Example 1, the component (E) was changed to UNIOX PKA5001 (manufactured by NOF Corporation, main chain skeleton: oxyethylene, terminal functional groups: allyl group and hydrosilyl group, number average molecular weight: A roller was prepared in the same manner as in Example 1, except that the roller was changed to 200). As a result of observing the roller surface, foaming and pinholes were confirmed on the roller surface.

[0036]

According to the present invention, the formed roller is
It has become possible to suppress appearance defects such as foaming on the surface and pinholes, which are problems when used in a portion that comes into contact with other rollers or members.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 71/00 C08L 71/00 A 71/02 71/02 F16C 13/00 F16C 13/00 A B G03G 15 / 08 501 G03G 15/08 501D F-term (reference) 2H077 AD06 FA22 3J103 AA02 AA13 AA32 BA41 FA14 FA30 GA02 GA52 GA57 GA58 GA60 HA03 HA05 HA12 HA15 HA20 HA33 HA53 4F071 AA51 AA67 AA78 AB03 AB06 AE03 AE15 AF37 CH05W CH053 CH054 CL074 CP04X DA037 DA067 DA116 DD076 EN137 FD010 FD114 FD117 GM00

Claims (5)

[Claims] 1. A curable composition for a roller comprising the following components (A) to (E) as essential components. (A) having at least one alkenyl group in the molecule,
(B) a polymer having at least two hydrosilyl groups in the molecule (C) a hydrosilylation catalyst (D) conductivity imparting Agent (E) A polymer having at least one alkenyl group at the terminal and having a number average molecular weight of 3,000 or less, wherein the main chain repeating unit is mainly composed of oxyalkylene units and has no active hydrogen in the molecule. 2. The curable composition for a roller according to claim 1, wherein the repeating unit of the main chain of the component (A) is oxypropylene. The component (E) is represented by the following general formula (1): R ₁ -OXOR ₂ (1) (R ₁ : alkenyl group, R ₂ : alkyl group or aryl group, X: main chain The curable composition for a roller according to claim 1, wherein the repeating unit is a polymer mainly composed of oxyalkylene units and having a number average molecular weight of 3,000 or less. 4. The curable composition for a roller according to claim 1, wherein the repeating unit of the main chain of the component (E) is oxypropylene. 5. The method according to claim 1, wherein the conductive shaft is provided around the conductive shaft.
A rubber roller provided with at least one rubber elastic layer comprising the curable composition for a roller according to any one of the above.