JPH0535109A - Polyurethane foam for roll - Google Patents

Abstract

PURPOSE:To reduce contaminant content in a polyurethane foam down to a specified level or less. CONSTITUTION:This polyurethane foam is a one for roll favorably used in contact with a photosensitive drum of a copying machine, etc., and is cleaned by solvent so that component extracted by acetone become <=3% by wt.% of the resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane foam for rollers used in various rollers in printers for electrophotography, electrostatic recording, etc., especially for rollers used in contact with a photosensitive drum.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic process in which toner prepared in a toner cartridge is supplied to a photosensitive member on which an electrostatic latent image is formed and transferred and fixed on a sheet is generally charged, exposed, developed, Transfer, fixing, static elimination,
It consists of various cleaning mechanisms, and various rollers are used in each mechanism. However, polyurethane foam has come to be widely used as a roller material because of its flexibility and low compression set.

[0003]

However, in particular, the rollers used in the charging, developing, transferring, and cleaning mechanisms are often used in contact with the photoconductor, and a roller made of polyurethane foam is used for such purposes. When used, there was a problem that the copy was unclear.

As a result of investigating the cause of copying problems when a polyurethane foam roller is used as described above, the present invention transfers unreacted monomers or oligomers and other non-reactive additives to the polyurethane foam forming the roller body. The purpose of the present invention is to provide a polyurethane foam for rollers which does not have such defects by finding out that the cause of the transfer of the pollutant to the photoconductor drum and contamination thereof and suppressing these pollutants to below a certain level. To do.

[0005]

In order to achieve the above-mentioned object, the present invention is a polyurethane foam for a roller, which is used as a suitable roller in contact with a photosensitive drum of a copying machine or the like, wherein the acetone extraction component is a resin. The solvent was washed so that the weight ratio was 3% or less.

[0006]

According to the present invention, the contact of the photosensitive drum does not contaminate the photosensitive drum and the characteristics of the polyurethane foam are not lost.

[0007]

EXAMPLE The polyurethane foam used in the present invention is
Foam hardening by stirring and mixing a compound containing two or more active hydrogens (polyhydroxyl compound) and a compound having two or more isocyanate groups (polyisocyanate compound) with additives such as catalysts, foaming agents, foam stabilizers, etc. Polyurethane foam formed by using the above, and as the polyhydroxyl compound, a polyol used for producing a general flexible polyurethane foam or urethane elastomer, that is, a polyether polyol having a polyhydroxyl group at the terminal,
In addition to polyester polyols and polyether polyester polyols which are copolymers of both,
A general polyol such as a so-called polymer polyol obtained by polymerizing an ethylenically unsaturated monomer in the polyol can be used. Further, as the polyisocyanate compound, a polyisocyanate commonly used in the production of flexible polyurethane foams and urethane elastomers can be used. That is, tolylene diisocyanate (TD
I), crude TDI, 4,4-diphenylmethane diisocyanate (MDI), crude MDI, C2-C18 aliphatic polyisocyanate, C4-C15 alicyclic polyisocyanate, and mixtures and modified products of these polyisocyanates For example, a prepolymer obtained by partially reacting with a polyol is used. Further, as the catalyst, the foaming agent, and the foam stabilizer, those used in the general production of urethane foam can be used as they are, and there is no particular limitation. Regarding the foaming method, general H ₂ O is used as a foaming agent, a method of foaming and hardening after stirring and discharging using a volatile solvent as a foaming agent, and a method of using a polyhydroxy component and a polyhydroxy component without using H ₂ O or an organic solvent. Catalyzing isocyanate component,
With a foam stabilizer, use a mechanical stirrer to foam and discharge beforehand.
Heat cure. The so-called mechanical floss method is also useful as a foam material for rollers. If necessary, various fillers, conductivity-imparting substances and the like can be added.

The solvent cleaning may be carried out either at the stage of the raw material of the polyurethane foam thus prepared or before the processing, or at the product shape of the roller integrated with the shaft. Any solvent may be used as long as it is compatible with unreacted monomers or oligomers, such as H ₂ O, alcohols, aromatic solvents such as benzene, toluene and xylene, aliphatic solvents such as hexane and cyclohexane, or THF and dioxane. Ether-based solvent such as DMF
Halogen-containing hydrocarbons such as amides and methylene chloride, and esters such as ethyl acetate are also included, and a mixture thereof is also used. That is, the solvent to be used and the washing method are not particularly limited, but it is important that the amount of unreacted monomers, oligomers and other migrating pollutants present in the polyurethane foam after washing is below a certain amount. The components extracted by acetone extraction must be 3% or less in terms of the resin amount ratio. In this case, the resin amount ratio of the acetone extraction component was determined by extracting a fixed amount of the foam sample (weight A) using a Soxhlet extractor, using acetone as a solvent and heating under reflux for 6 hours to perform extraction. The foam remaining as a residue is sufficiently heated and dried, and its weight is measured (this is referred to as B), and it is determined by the following formula. Extraction component rate = [(A−B) / A] × 100 (%) (A)

Production Example Polyether polyol having a molecular weight of 5000 by adding propylene oxide and ethylene oxide to glycerin (Exenol 828 of Asahi Glass Co., Ltd.) (OH value 33)
………… 100 parts Urethane-modified MDI (Sumijour PF of Sumitomo Bayer Urethane Co., Ltd.) (NCO% = 23%) …………
25.0 parts 1.4-Butanediol ………… 2.5 parts Silicone surfactant (L-520 manufactured by Nippon Unica Co., Ltd.) ……
...... 1.5 parts Nickel acetylacetonate ............ 0.5 parts Dibutyltin diurarate ............ 0.01 parts Average particle size 2.5 μm Natural graphite with fixed carbon content of 99% (Nippon Graphite Co., Ltd.) High-purity graphite AOP) …………
50 parts (28% by weight relative to the total amount of resin) These were placed in a 1-liter plastic container and stirred for 2 minutes with a domestic whisk to obtain a foam having fine uniform cells. This foam is 200mm long x 30mm wide x 30 deep
It was poured into a mold of mm and heated at 140 ° C. for 7 minutes to be cured to obtain a polyurethane foam for rollers.

The polyurethane foam thus obtained was immersed in acetone in a container with stirring and convection and then dried in vacuum to see the cleaning effect. The degree of cleaning was changed by changing the immersion time in acetone. .. Contamination of these photoreceptors was evaluated by copying the foam sample after pressing the foam sample against the photosensitive drum of a commercially available printer after 50 days at 50 ° C. The evaluation was evaluated as ◯ when the entire black copy was not affected by the pressure contact portion at all, Δ when slightly contaminated and slightly blurred black, and × when clearly whitened.
The results are shown in Table 1.

[0011]

[Table 1]

Similarly, Table 2 shows the results of an experiment conducted using methylene chloride as a solvent.

[0013]

[Table 2]

That is, regardless of the type of solvent to be washed, when the acetone extraction component ratio becomes 3% or less, the contamination property disappears.

[0015]

As described above, according to the present invention, since the polyurethane foam used for the roller is solvent-cleaned and the acetone extraction component ratio is 3% or less,
This polyurethane foam does not contaminate the contacted object.

Claims (1)

Claim: What is claimed is: 1. A polyurethane foam for a roller, which is used as a suitable roller in contact with a photosensitive drum of a copying machine or the like, wherein the acetone extraction component is 3% or less by weight of the resin. Polyurethane foam for rollers, characterized by being solvent washed.