JPH0566589B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field of the invention] The present invention involves heating a toner powder image of dry electrophotography.
The present invention relates to a heat fixing roll that performs fixing by applying pressure, and more particularly to a heat fixing roll that exhibits less distortion due to heating, less adhesion of toner, and excellent releasability. [Technical background of the invention and its problems] Conventionally, in dry electrophotography, a toner powder image is formed using a heated rubber roll as a means for fixing a toner powder layer transferred from a transfer drum or the like onto a support such as paper. A method of fixing by applying pressure onto a support is considered to be appropriate. It is well known that silicone rubber is used for the heat fixing roll used in this method due to its excellent heat resistance. (2) liquid silicone rubber that hardens by condensation reaction (e.g., Japanese Patent Publication No. 1277/1983);
No. 2439, Japanese Patent Application Laid-open No. 1975-75446) and (3)
Liquid silicone rubbers (for example, Japanese Patent Application Laid-open No. 149354/1983) that are cured by addition reactions have been disclosed. Silicone rubber produced by these three types of curing methods each has its own advantages and disadvantages, and is used for various types of copying machines depending on the required performance. In other words, while (1) the toner cured with organic peroxide has excellent mechanical properties, it has poor toner releasability from the roll (hereinafter referred to as toner releasability), and (2) the toner cured by condensation reaction has poor mechanical properties. The releasability is good compared to other types, but the compression set is large, and the compression set due to addition reaction (3) is small compared to other types, but the toner releasability is compared to (2). And expensive. In recent years, the production and demand for electrostatic plain paper copying machines has rapidly increased, and high quality heat fixing rolls with lower compression set and excellent toner releasability are required. To improve the toner releasability, there are methods to add silicone oil to the composition or to bleed the oil into the roll surface layer by impregnation, but as the oil bleeds over time, it decreases over time and causes toner stains. There are problems in that the diameter of the roll becomes thinner. In addition, among the fillers used in silicone rubber, conventional ones or a combination thereof, such as silica-based reinforcing fillers, semi-reinforcing fillers such as crystallite and celite, and their combination can improve toner releasability. has reached its limit. [Object of the Invention] As a result of studies on fillers for improving these properties, the present inventors have developed a polyorganosiloxane composition that has excellent properties by using polymethylsilsesquioxane as a filler. was found to be obtained. The present invention has been made based on the above findings, and an object of the present invention is to provide a heat fixing roll that retains the inherent advantages of conventional silicone rubber rolls and has excellent toner releasability. [Structure of the Invention] The present invention is based on a silicone rubber obtained by curing a polyorganosiloxane composition basically consisting of (A) a polyorganosiloxane (B) a curing agent (C) a polymethylsilsesquioxane powder. A heat fixing roll having at least a surface layer thereof. The polyorganosiloxane composition in the present invention includes basic components (A) polyorganosiloxane base polymer, (B) curing agent, and (C) polymethylsilsesquioxane powder, and if necessary, a reinforcing filler. , various additives are uniformly dispersed. Among the various ingredients used in these compositions,
The polyorganosiloxane (A) and the curing agent (B) are:
It is appropriately selected depending on the reaction mechanism for obtaining the rubber elastic body. The reaction mechanisms include (1) a crosslinking method using an organic peroxide vulcanizing agent, (2) a method using a condensation reaction, and (3) a method using an addition reaction. It is well known that preferred combinations of polymer and (B) curing agent, ie, curing catalyst or crosslinking agent, are determined. That is, in the crosslinking method (1), usually (A)
A polydiorganosiloxane in which at least two of the organic groups bonded to silicon atoms in one molecule are vinyl groups is used as the base polymer. In addition, as a curing agent for (B), benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, cumyl-t-butyl peroxide, 2,5-di-t-butylperoxyhexane, di-t-butyl peroxide, etc. Various organic peroxide vulcanizing agents are used, but dicumyl peroxide, cumyl-t-butyl peroxide,
2,5-di-t-butylperoxyhexane and di-t-butylperoxide are preferred. Note that these organic peroxide vulcanizing agents can be used alone or as a mixture of two. The amount of organic peroxide that is the curing agent in (B) is (A)
per 100 parts by weight of polyorganosiloxane
It is preferably selected from the range of 0.05 to 15 parts by weight. If the amount of organic peroxide (B) is less than 0.05 parts by weight, vulcanization will not be sufficient, and if it exceeds 15 parts by weight, not only will there be no particular effect, but the physical properties of the resulting silicone rubber molded product will be adversely affected. This is because it may give. In the condensation reaction (2), a polydiorganosiloxane having hydroxyl groups at both ends and a viscosity of 50 to 500,000 cSt at 25°C is used as the base polymer of (A), and methyl is used as the crosslinking agent as the curing agent of (B). Trimethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxylane, methyltripropoxysilane, ethyl orthosilicate, propyl orthosilicate and their partially hydrolyzed/condensed products are used as curing catalysts such as iron octoate, Cobalt octoate, manganese octoate, tin naphthenate,
Carboxylic acid metal salts such as tin caprylate, tin oleate, dimethyltin dioleate, dimethyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dioleate, diphenyltin diacetate, dibutyltin oxide, dibutyltin Organotin compounds such as dimethoxide, dibutylbis(triethoxysiloxy)tin, and dioctyltin dilaurate are used. The amount of crosslinking agent used is 0.1 per 100 parts by weight of component (A).
~20 parts by weight. If the amount is less than 0.1 part by weight, the rubber after curing will not have sufficient strength, and if it exceeds 20 parts by weight, the resulting rubber will become brittle, and both are not suitable for practical use. Further, the amount of the curing catalyst added is 0.01 to 5 parts by weight. If the amount added is less than this, it will be insufficient as a curing catalyst, and curing will take a long time, and curing will be poor in areas far from the surface in contact with air. On the other hand, if the amount is more than this, the storage stability will decrease, which is not appropriate. A more preferable range of addition amount is 0.1 to 3 parts by weight. In the addition reaction of (3), the base polymer of (A) should be heated at 25°C in which at least two of the organic groups bonded to silicon atoms in one molecule are alkenyl groups.
A polydiorganosiloxane having a viscosity of 50 to 500000 cSt is used as the curing agent for (B), and as a curing catalyst, chloroplatinic acid, platinum olefin complex,
A polydiorganosiloxane in which a platinum-based catalyst such as a platinum vinyl siloxane complex, platinum black, or platinum triphenylphosphine complex is used, and the number of hydrogen atoms bonded to silicon atoms as a crosslinking agent exceeds an average of at least two per molecule. is used. The amount of the curing catalyst blended is in the range of 1 to 100 ppm in platinum atoms based on component (A). If it is less than 1 ppm, the effects of the present invention cannot be achieved, and if it exceeds 100 ppm, no improvement in curing speed can be expected. The amount of crosslinking agent to be used is such that the number of silicon-bonded hydrogen atoms in the crosslinking agent is 0.5 to 4.0, preferably 1.0 to 3.0, per one alkenyl group in component (A). It is. If the number of hydrogen atoms is less than 0.5, the curing of the composition will not proceed sufficiently and the hardness of the composition after curing will be low, and if the number of hydrogen atoms exceeds 4.0, the physical hardness of the composition after curing will decrease. Properties and heat resistance decrease. The organic group of the polyorganosiloxane (A) used in the various reaction mechanisms described above is a monovalent substituted or unsubstituted hydrocarbon group, and includes a methyl group, ethyl group, propyl group, butyl group, and hexyl group. , alkyl groups such as dotecyl group, aryl groups such as phenyl group, β-phenylethyl group, β-
Examples include aralkyl groups such as phenylpropyl group, and further examples include chloromethyl group and 3,3,3-trifluoropropyl group, but in general, methyl group is often used due to ease of synthesis. be done. The polymethylsilsesquioxane powder used as component (C) in the present invention is a reinforcing agent and/or a mold release improving agent for silicone rubber. This filler has a lower specific gravity when made into a compound than other silica-based fillers with similar average particle sizes, such as crushed quartz and diatomaceous earth, so even when filled in large amounts, the specific gravity of the system remains low. Moreover, when used in liquid silicone rubbers (2) and (3), the system exhibits little increase in viscosity and is highly fluid. As polymethylsilsesquioxane powder,
The product obtained by hydrolyzing and condensing methyltrialkoxysilane or its hydrolysis/condensation product in an aqueous solution of ammonia or amines has almost no impurities such as chlorine atoms, alkaline earth metals, and alkali metals. It is preferable because it is spherical and has excellent free-flowing properties. The average particle size of polymethylsilsesquioxane powder is 0.1 to 100 μm, and even 0.1 to 100 μm.
20 μm is preferred. If it is less than 0.1 μm, it is difficult to manufacture and it is difficult to fill more than necessary, and if it exceeds 100 μm, it is difficult to obtain the necessary reinforcing effect and it becomes difficult to obtain the functions necessary for the present invention. The blending amount is 0.5 to 300 parts by weight, preferably 0.5 to 200 parts by weight, based on 100 parts by weight of the polyorganosiloxane (A). If it is less than 0.5 parts by weight, no mold release effect will be obtained, and if it exceeds 300 parts by weight, it will be difficult to incorporate into the system, and furthermore, the elasticity of the rubber after curing will be poor, not only will the reinforcing effect be lost, but the mechanical properties will deteriorate. The composition of the present invention may additionally contain fillers other than polymethylsilsesquioxane powder, pigments, heat resistance improvers, adhesion aids, flame retardants, etc., as necessary. Other polyorganosiloxanes may be used in combination within a range that does not impair the effect. Such additives typically include fumed silica, precipitated silica, diatomaceous earth, titanium oxide, aluminum oxide, zinc oxide, iron oxide, cerium oxide, mica, clay, carbon black,
Examples include graphite, calcium carbonate, zinc carbonate, manganese carbonate, cerium hydroxide, glass beads, metal powder, polydimethylsiloxane, and alkenyl group-containing polysiloxane. The composition comprising the above-mentioned components may be solid or fluid. Although the mixing conditions are not particularly limited, component (C) and other fillers and additives as necessary are added to component (A) and dispersed uniformly, and at the time of manufacturing the rubber roll, (B) is added. Preferably, the ingredients are mixed. A roll using the silicone composition described above is formed by utilizing the reaction mechanism for obtaining the rubber elastic body described above. For example, in a crosslinking method using an organic peroxide vulcanizing agent, a method using a compression molding method in which a silicone composition is coated around a core metal that has been primed by brushing or spraying, or an addition reaction or condensation In the reaction method, a rubber roll can be obtained by injection molding or a general curing method for liquid rubber depending on the viscosity of the silicone composition. In addition, when an organic peroxide vulcanizing agent is used, the decomposition residue of the organic peroxide in the molded product can be removed by heating the molded product at 150 to 200°C for several hours. preferable. A fixing roll is obtained by polishing the roll thus obtained. [Examples of the Invention] The present invention will be described below with reference to Examples. In the examples, all parts indicate parts by weight. Note that these Examples do not limit the present invention. First, polymethylsilsesquioxane powder was synthesized by the following method. Reference Example 1 A four-necked flask equipped with a thermometer, a reflux device, and a stirrer was charged with the amount of water shown in Table 1 and an ammonia aqueous solution with a concentration of 28%, and methyltrimethoxysilane was added to the ammonia aqueous solution. was gradually added dropwise over 60 to 120 minutes while stirring. The reaction temperature started at 10°C and reached 30°C at the end of the dropwise addition. Next, the mixture was heated with a mantle heater to reflux at 84°C, and stirring was continued at this temperature for about 1 hour. After cooling, the precipitated product in the flask is collected, washed with water, dried, and then subjected to a pulverization process to produce powdered polymethylsilsesquioxane (F-1 to F) with excellent free-flowing properties shown in Table 1. -4) was obtained.

[Table] Reference Example 2 9 parts of water were added to 178 parts of methyltriethoxysilane containing 1% by weight of chlorine atoms, and the mixture was heated at 80°C for about 2 hours to obtain a partially hydrolyzed/condensed product. When this was dropped into 500 parts of a 3% by weight aqueous solution of ethylenediamine and hydrolyzed and condensed under the same conditions as in Reference Example 1, powdered polymethylsilsesquioxane (F-5 )was gotten. Example 1 100 parts of polydimethylsiloxane, which has an average degree of polymerization of 5000, contains 0.2 mol% of methylvinylsiloxane units, and whose terminals are blocked with hydroxyl groups, and 80 parts of powder F-1 were uniformly blended using two rolls, 2 more,
0.5 part of 5-dimethyl-2,5-di-t-butylperoxyhexane was added and mixed at room temperature to form Composition 11.
was prepared. Comparative Example 1 Comparison was made under the same conditions as in Example 1 except that 30 parts of wet silica carplex #80 (manufactured by Shionogi Pharmaceutical Co., Ltd.) with a specific surface area of 230 m ² /g was used instead of powder F-1. Composition 12 was prepared. Comparative Example 2 Comparative composition 13 was obtained in the same manner as in Example 1 except that 40 parts of Celite Super Floss (manufactured by John Manville) was used instead of powder F-1. Composition 11 and comparative compositions 12 and 13 were placed in a chrome-plated mold and pressed at 170°C for 10 minutes under a pressure of 100 kgf/cm ² to form silicone rubber sheets of 2 mm and 6 mm thickness. Obtained. Next, this sheet was subjected to atto-vulcanization at 200° C. for 4 hours, and then tested for mechanical properties, compression set, and surface tack according to JISK6301 at room temperature. The results are shown in Table 2. Furthermore, the compression set is
Heated at 180℃ for 22 hours, surface adhesion test according to Note 1. Note 1 Surface adhesion test 2.5 cm wide and 10 cm long on a silicone rubber sheet.
tape (Scotchi 5490 manufactured by Sumitomo 3M) at 10gf/
After bonding at a pressure of cm ² at room temperature for about 5 hours, a peel test was performed at 180 °C at a peel rate of 10 mm/min using an autograph, and the average load at that time was
It is expressed as peeling force (unit gf/cm) converted per cm. The smaller the peeling force, the better the surface non-adhesiveness. In addition, each composition was press-cured under the above conditions in a cylindrical mold into which a roll core metal treated with a primer was inserted, and after further atto-vulcanization at 200°C for 4 hours, it was polished and used for heat fixing. Got the roll. The copy life test of Note 2 was conducted on this roll. The results are shown in Table 2. Note 2 Copy life test The fuser roll manufactured according to each example below was replaced with the fuser roll attached to the Toshiba Leo Barai 7811 dry electrophotographic copying machine, copies were made continuously under the following operating conditions, and the fuser roll was The copy life was defined as the number of copies until stains (Macbeth density 1.0 or higher) appeared. Fusing temperature 180℃ Fusing pressure 4Kgf/cm ² Original Text document with image area ratio of approx. 20% Copying speed 28 sheets/min Copy paper Size A4 for Toshiba RheoDry 7811 Toner used Toner for Toshiba RheoDry 7811

[Table] Example 2 Average degree of polymerization is 6000, methylvinylsiloxane unit is 0.2 mol%, diphenylsiloxane unit is 5%
Wet silica containing mol%, 100 parts of polydimethylsiloxane whose terminals are blocked with dimethylvinylsiloxy groups, 50 parts of powder F-2, and a specific surface area of 230 m ² /g.
Knead 20 parts in a kneader until uniform,
Further, 0.6 part of dicumyl peroxide was uniformly mixed at room temperature using two rolls to obtain Composition 21. Comparative Example 3 Comparative composition 22 was obtained in the same manner as in Example 2, except that heavy calcium carbonate NS #400 (manufactured by Nitto Funka Kogyo Co., Ltd.) was used instead of powder F-2. The physical properties of Composition 21 and Comparative Composition 22 were determined in the same manner as in Example 1 and Comparative Examples 1 and 2.
Peel force and offset properties were measured. The results are shown in Table 3.

[Table] Example 3 30 parts of Powder F-3 was added to 100 parts of polydimethylsiloxane base oil having a viscosity of 100,000 cP at 25°C and having dimethylhydroxysilyl groups blocked at both ends, and the mixture was mixed uniformly. To this, 5.5 parts of methyltrimethoxysilane, 0.5 parts of dimethyltin dilaurate,
Composition 31 was prepared by adding 0.1 part of water and mixing to uniformly disperse the mixture. Example 4 Composition 32 was prepared in the same manner as in Example 3 except that 15 parts of Aerosil 200 and 5 parts of Powder F-3 were added instead of 30 parts of Powder F-3. Comparative Example 4 Comparative composition 33 was obtained in the same manner as in Example 3 except that 18 parts of Aerosil 200 were added instead of 30 parts of powder F-3. Compositions 31, 32 and comparative composition 33 were poured into a plastic mold, left at room temperature for 2 days, and then removed from the mold.
The sheets were further left at room temperature for 3 days to obtain sheets with a thickness of 2 mm and a thickness of 6 mm. This sheet was heat treated at 200° C. for 4 hours, then returned to room temperature and subjected to mechanical properties, compression set, toner peeling test and copy life test based on JIS K6301. The results are shown in Table 4. In addition, the compression set is at 180℃.
Measurements were taken after heating for 22 hours, and the toner peeling test was conducted in the following manner. (Toner Peeling Test) After heat treatment, a 2 mm thick sheet returned to room temperature was cut into two tanzak shapes of 30 mm x 130 mm, and the surface was sufficiently polished with sandpaper (No. 1000). The edge of the polished surface of this sheet 30mm x
Apply toner EP310 (manufactured by Minolta Co., Ltd., trade name) evenly to the surface of the 100mm. Then, as shown in the drawing, the toner-coated surfaces of the two sheets are overlapped,
Crimp at 180℃ for 30 minutes (with a 1000g weight). In addition, in the drawing, ₁ = 30mm, ₂ = 100
mm. Next, it is returned to room temperature and pulled in a 180° direction using a tensile tester equipped with an automatic recorder, and the force required to peel off the crimped portion is defined as the "toner peeling force." The smaller this value is, the better the releasability is. Table 4 shows the results of comparing the physical properties, toner releasability and offset properties of Compositions 31, 32 and Comparative Composition 33.

【table】

[Table] Example 5 100 parts of polydimethylsiloxane base oil with a viscosity of 3000 cP at 25°C and blocked with dimethylvinylsilyl groups at both ends, 54 parts of powder F-4, (CH ₃ ) ₂
2 parts of polyorganohydrodiene siloxane consisting of HSiO _1/2 units and SiO ₂ units and containing 1.02% by weight of hydrogen atoms bonded to silicon atoms and having a viscosity of 21 cP at 25°C and a solution of chloroplatinic acid in isopropyl alcohol as platinum atoms. Mix 10ppm of the base oil and disperse it evenly to create a composition.
Adjusted 41. Comparative Example 5 Comparative composition 42 was prepared under the same conditions as in Example 5 except that 35 parts of fumed silica Aerosil 200 (manufactured by Degutsusa Co., Ltd., trade name) was used instead of powder F-4. Comparative Example 6 In Example 5, Celite Super Floss (manufactured by John Manville, trade name) was used instead of powder F-4.
Comparative composition 43 was obtained in the same manner except that 50 parts were used. Composition 41 and Comparative Compositions 42 to 43 were poured into a mold, and then pressed at 170°C for 10 minutes to obtain sheets with a thickness of 2 mm and a thickness of 6 mm. This sheet is 200
After heat treatment at ℃ for 4 hours, return to room temperature,
Mechanical properties based on JISK6301, compression set,
A toner peel test and a copy life test were conducted. The results are shown in Table 5.

[Table] Example 6 100 parts of polydimethylsiloxane base oil with a viscosity of 10,000 cP at 25°C with dimethylvinylsilyl groups blocked at both ends, 18 parts of Aerosil 200, powder F-
5 parts of (CH ₃ ) ₂ HSiO _1/2 units and SiO ₂ units, containing 1.02% by weight of hydrogen atoms bonded to silicon atoms.
Contains 1.3 parts of polyorganohydrodiene siloxane with a viscosity of 21 cP at 25°C, 6 parts of polydimethylsiloxane with a viscosity of 100 cSt at 25°C, 5 parts of silicone oil, and an isopropyl alcohol solution of chloroplatinic acid at 8 ppm based on the base oil as platinum atoms. were mixed and uniformly dispersed to prepare Composition 51. Example 7 Composition 62 was prepared in the same manner as in Example 6 except that 10 parts of Powder F-5 were used instead of 5 parts. Example 8 Composition 63 was prepared in the same manner as in Example 6 except that 20 parts of powder F-5 was used instead of 5 parts. Comparative Example 7 Comparative composition 64 was prepared in the same manner as in Example 6 except for excluding powder F-5. Comparative Example 8 To Comparative Composition 64 of Comparative Example 7, 5.0 parts of Celite Super Floss was added to 100 parts of base oil in the composition, and the mixture was mixed and uniformly dispersed to prepare Comparative Composition 65. Sheets and rolls were produced for Compositions 61 to 63 and Comparative Compositions 64 to 65 in the same manner as in Example 5, and subjected to mechanical properties, compression set, toner peeling test, and copy life test based on JIS K6301. The results are shown in Table 6.

[Table] [Effects of the Invention] According to the polyorganosiloxane composition of the present invention, it is possible to obtain a heat fixing roll that has significantly improved compression set and toner releasability, and has a significantly longer copy life.

[Brief explanation of the drawing]

The drawings are diagrams showing the state of a sheet in a toner peeling test of an example of the present invention.

Claims (1)

[Scope of Claims] 1. (A) polyorganosiloxane (B) curing agent (C) polymethylsilsesquioxane powder. A heat fixing roll composed of layers. 2. Claim 1, wherein (C) is polymethylsilsesquioxane powder obtained by hydrolyzing and condensing methyltrialkoxysilane or its hydrolyzed and condensed product in an aqueous solution of ammonia or amines. The heat fixing roll described. 3. The heat fixing roll according to claim 1 or 2, wherein (C) has an average particle diameter of 0.1 to 100 μm. 4 The blending amount of (C) is 0.5 to 300 parts by weight per 100 parts by weight of (A).
The heat fixing roll according to any one of claims 1 to 3, which is in parts by weight.