JPH0240571B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a paper feed roll for electrophotographic copying machines that has excellent toner resistance. Conventionally, rolls made of softened polyurethane have been used as paper feed rolls in electrophotographic copying machines. Rolls made of such softened polyurethane have excellent mechanical properties such as abrasion resistance, but they also contain oils and plasticizers such as dioctyl phthalate, dioctyl adipate, or dipropylene glycol dibenzoate. , softened to have appropriate hardness. As a result, conventional paper feed rolls made of polyurethane containing these plasticizers have a problem of poor toner resistance. In other words, a so-called bleeding phenomenon occurs in which plasticizers and oil ooze out onto the roll surface over time, and the oozing plasticizer and oil dissolve the resin that makes up the toner, causing the roll surface to bleed while the copying machine is in use. Toner sticks and accumulates on the paper, reducing paper feeding performance. Furthermore, if bleeding occurs in the paper feed roll, it can also contaminate the copy paper. In addition, the temperature inside an electrophotographic copying machine is often 10 to 20 degrees Celsius higher than the environmental temperature when the machine is used, and therefore the paper feed roll has a temperature of around 0 degrees Celsius to 50 degrees Celsius.
Constant paper feeding performance is required over a wide temperature range that includes nearby high temperatures, but paper feeding rolls made of softened polyurethane such as those described above do not have sufficient temperature stability and are difficult to use when used at high temperatures. The adhesion of toner to the paper feed roll and the reduction in the coefficient of friction of the surface required for the paper feed roll become more pronounced. The present invention substantially does not cause bleeding phenomenon, maintains the required coefficient of friction, and has excellent temperature stability at high temperatures. Therefore, it has excellent toner resistance and can be used even under high temperatures inside a copying machine. An object of the present invention is to provide a paper feed roll for an electrophotographic copying machine having stable paper feed performance and a method for manufacturing the same. The paper feed roll for an electrophotographic copying machine according to the present invention includes:
A urethane prepolymer made by reacting a polyol and a polyisocyanate, a curing agent, and a urethane prepolymer that has two or more hydroxyl groups in the molecule and has an average molecular weight.
It is characterized by being formed by molding a composition consisting of a reactive oligomer having a molecular weight of 500 to 3,000. The urethane prepolymers used in the present invention are preferably obtained by reaction of polyols such as polyester polyols or polyether polyols with polyisocyanates according to conventional methods. Such urethane prepolymers are commercially available. Examples of the polyol include one or a mixture of two or more glycols such as ethylene glycol, butylene glycol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, or neopentyl glycol, and adipic acid, etc. Polyester polyols such as polyester polyols obtained by reacting with dicarboxylic acids having 2 to 6 carbon atoms, polycarbonate ester polyols, polycaprolactone ester polyols obtained by ring-opening polymerization of caprolactone, and polyoxymethylene glycols. , polyether polyols such as polyoxypropylene glycol are preferably used. In addition, as the polyisocyanate, tolylene diisocyanate, diphenylmethane-4,
4'-diisocyanate, naphthalene-1,5-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and the like are preferably used. However, the polyol and polyisocyanate in the urethane prepolymer used in the present invention are not limited to the above. As mentioned above, in a paper feed roll made of polyurethane, it is necessary that the polyurethane be softened. Therefore, the urethane prepolymer composition for forming the paper feed roll for an electrophotographic copying machine according to the present invention It is necessary to contain a plasticizer. Here, the above composition contains, as a plasticizer, a reactive oligomer having two or more hydroxyl groups in the molecule and having an average molecular weight of 500 to 3,000. Such reactive oligomers are chemically bonded to the urethane prepolymer molecules during crosslinking and curing of the urethane prepolymer through two or more hydroxyl groups in the molecule, so that bleeding does not occur on the surface after molding. Moreover, since it has a high molecular weight and a long molecular chain, a certain distance is created between the urethane prepolymer molecules via the crosslinked chains, and thus a polyurethane paper feed roll that is appropriately softened can be obtained. Obtainable. Examples of the above-mentioned reactive oligomers include polyols such as polyester polyols and polyether polyols, liquid polybutadiene rubber, and silicone rubber. Preferred specific examples include, for example, organic acids such as polyethylene adipate, and polyols such as polyester polyols and polyether polyols. Examples include condensates of alcohols, ring-opening polymers such as caprolactone esters and polyoxyethylene glycol, and liquid rubbers such as silicone and butadiene rubbers. However, it is not limited to these. In the present invention, the molding composition has the above-mentioned reactivity with respect to 100 parts by weight of the urethane prepolymer so that the resulting paper feed roll made of polyurethane has a hardness in the range of 10 to 60 degrees according to JIS A method. It is preferable to contain 10 to 100 parts by weight of oligomer. This is because when the amount of the reactive oligomer is out of this range, when it is formed into a paper feed roll for an electrophotographic copying machine, it will not be possible to give it the above-mentioned appropriate hardness. The composition used in the present invention further contains a curing agent. The amount of the curing agent to be blended is preferably 2 to 8 parts by weight per 100 parts by weight of the urethane prepolymer in order to achieve a preferable softening of the paper feed roll for electrophotographic copying machines. Specific examples of curing agents used include 4,4-methylenebis(2-chloroaniline), triisopropanolamine, ethylene glycol, 1,4-butanediol, 2,3-butanediol, 1,1,
1-trimethylolpropane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-
Diaminodiphenylmethane and hydroquinone
Bis(β-hydroxylethyl) ether may be used alone or as a mixture. The above-mentioned composition can be formed into a paper feed roll for an electrophotographic copying machine according to the present invention by a conventional method known in the production of polyurethane moldings. For example, a mixture consisting of a urethane prepolymer, the reactive oligomer, and a curing agent is poured into a predetermined mold heated to about 100°C,
After heating for several hours, it is removed from the mold and baked in heated air at 90°C for about 10 hours. The thus obtained paper feed roll for electrophotographic copying machines does not bleed not only at room temperature but also at high temperatures around 50°C, and therefore, toner does not stick to the roll surface due to bleeding. It has good toner resistance and also has a resistance of 200% at room temperature.
There is virtually no decrease in the coefficient of friction for a long period of time, even after days or under severe conditions due to temperature changes of -10 to 60°C. As described above, according to the present invention, a paper feed roll for an electrophotographic copying machine is obtained using a urethane composition containing a high molecular weight and reactive oligomer as a plasticizer. The paper feed roll produced has non-bleeding properties and excellent toner resistance. Examples are shown below, but the present invention is not limited to these Examples. In the examples, parts indicate parts by weight. Example (1) Invention 1 100 parts of urethane prepolymer (Takenate L1270, manufactured by Takeda Pharmaceutical Co., Ltd.), polyethylene adipate with an average molecular weight of 2000 and a hydroxyl value of 55 as a reactive oligomer (manufactured by Dainippon Ink and Chemicals Co., Ltd.)
50 parts of ODX102) and a mixture of 4,4-methylenebis(2-chloroaniline) and triisopropanolamine as a curing agent (3:7 molar ratio)
Mix 3 parts and pour into a mold heated to 100℃.
After heating, remove from the mold and heat with heated air at 90℃.
After baking for 12 hours, a paper feed roll of product 1 of the present invention was obtained. (2) Invention 2 In the same manner as in (1) above, except that 50 parts of polytetramethylene glycol (Sanyo Chemical Industries, Ltd. PTMG3000) having an average molecular weight of 3000 and a hydroxyl value of 34 to 40 was used as the reactive oligomer. A paper feed roll of product 2 of the present invention was obtained. (3) Invention Product 3 4 parts of the same curing agent as in (1), liquid rubber with an average molecular weight of 2000 as a reactive oligomer (manufactured by Nippon Soda Co., Ltd.)
A paper feed roll of product 3 of the present invention was obtained in the same manner as in (1) above, except that 30 copies of NISSO PBG-2000) were used. (4) Comparison product Same as (1), 5 parts of hardening agent, plasticizer (Benzoflex 9-88 manufactured by Versicol, molecular weight 341) 30
A comparison paper feed roll was obtained in the same manner as in (1), except that the sample was used in the same manner as in (1). (5) Changes in toner resistance and friction coefficient of each paper feed roll over time Place each paper feed roll in a container, and then feed it with toner (Toner 1 or 2) or resin powder (polyester resin powder or AS resin powder). After the entire paper roll was covered and left at 50° C. for 3 days and at room temperature for 200 days, the powdered toner or resin adhering to the roll was removed and the thickness of the toner or resin adhered to the roll was measured. The results are shown in Table 1. The value indicates the thickness (mm) of the layer of toner or resin powder adhered to the surface of each roll.

【table】

【represent. According to the paper feed roll of the present invention, at 50℃
Under both conditions of 1 day and 200 days at room temperature, there was no adhesion of toner or resin powder to the surface, and no bleeding occurred. On the other hand, in the comparative product, toner or resin powder adhered to a thickness of 0.5 to 1.0 mm. Next, each roll was left at room temperature for 200 days and -10℃
After being exposed to continuous temperature changes (heat cycle) for 6 hours at room temperature, 6 hours at 60℃, and 6 hours at room temperature, the friction coefficient of each roll surface was measured using a Heydon friction coefficient measuring device. was measured. The results are shown in Table 2. According to the roll of the present invention, the friction coefficient did not change at all under any conditions, but the friction coefficient of the comparative product significantly decreased both at room temperature and under heat cycle conditions.

Claims (1)

[Claims] 1 100 parts by weight of a urethane prepolymer obtained by reacting a polyol and a polyisocyanate, a curing agent, and having two or more hydroxyl groups in the molecule, and
Reactive oligomers with an average molecular weight of 500-3000
A paper feed roll for an electrophotographic copying machine, characterized in that it is formed by molding a composition comprising 10 to 100 parts by weight.