PNR for paper roller application.Recent technical progress in the area of office automation equipment has made possible remarkable performance advancements in plain paper copiers, laser printers and facsimile machines. Improved properties of print imaging, speed and maintenance-free operation are especially required in today's demanding office environment. Critical to office automation equipment are very low durometer paper feeding rollers used to transport paper of varying quality and thickness throughout the office machine. These rollers play a very important role in feeding papers one by one, without error, at ever increasing speeds. Paper feeding rollers, which pick up paper from the paper cassette A removable magnetic tape storage module that contains supply and takeup reels (hubs) in the same housing. Most audio tapes and videotapes use cassettes as well as backup tape technologies such as DAT, 8mm and Magstar MP (see below). to feed and convey them, use the frictional frictional pertaining to or emanating from friction. frictional acanthosis see acanthosis nigricans. force between the roller and paper. This key property must be maintained for the life of the machine. Because of this, paper feed rollers require the basic properties of high friction coefficient coefficient /co·ef·fi·cient/ (ko?ah-fish´int) 1. an expression of the change or effect produced by variation in certain factors, or of the ratio between two different quantities. 2. , abrasion abrasion /abra·sion/ (ah-bra´zhun) 1. a rubbing or scraping off through unusual or abnormal action; see also planing. 2. a rubbed or scraped area on skin or mucous membrane. resistance, low compression set and low hardness, within the service temperature and ozone range in which the machine will operate. The long-term stability The long-term stability of an oscillator, the degree of uniformity of frequency over time, when the frequency is measured under identical environmental conditions, such as supply voltage, load, and temperature. of these basic properties is a must to achieve longer maintenance-free machine life. Also of consideration is pollution of the paper feed roller. During large copy runs, paper dust is generated from the paper feed which can adhere to adhere to verb 1. follow, keep, maintain, respect, observe, be true, fulfil, obey, heed, keep to, abide by, be loyal, mind, be constant, be faithful 2. the surface of the roller. Gradually, the performance of the paper feed roll decreases. Highly oil extended polynorbornene rubber (PNR PNR Partner PNR Passenger Name Record (airlines) PNR Policía Nacional Revolucionaria (Cuban police) PNR Philippine National Railways PNR Point of No Return PNR Polymerase Chain Reaction ) compounds exhibit low hardness, high tensile strength tensile strength Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its , high friction, abrasion and pollution resistance critical for use in paper feeding rollers for today's high-tech office machines. This article will demonstrate the outstanding properties of highly oil extended PNR compounds, by focusing on their basic properties and then on their functional performance in paper feeding rolls. Experimental To produce oil extended PNR, powered PNR was mixed in a 3.0 liter liter, abbr. l, unit of volume in the metric system, defined since 1964 as equal to 0.001 cubic meters, or 1 cubic decimeter. A cube that has each of its edges equal to 10 centimeters has a volume of 1 liter. The liter is equal to 1.057 liquid quarts, 0. kneader knead tr.v. knead·ed, knead·ing, kneads 1. To mix and work into a uniform mass, as by folding, pressing, and stretching with the hands: kneading dough. 2. for ten minutes at 50 [degrees] C. The PNR compound without curatives was obtained by mixing with EPDM EPDM Ethylene-Propylene-Diene-Monomer EPDM Enterprise Product Data Management EPDM Ethylene Propylene Dimonomer (industrial/commercial piping/plumbing components) EPDM Engineering Product Data Management , fillers, antioxidants Antioxidants Substances that reduce the damage of the highly reactive free radicals that are the byproducts of the cells. Mentioned in: Aging, Nutritional Supplements antioxidants, n. , activators, etc., in a 3.0 liter kneader for ten minutes at 50 [degrees] C. Physical properties The Japan Industrial Standards (JIS JIS Japanese Industrial Standard JIS Jamaica Information Service JIS Juggling Information Service JIS Just in Sequence (automotive industry) JIS Jakarta International School JIS Joint Information System K 6250-6264) were employed for basic physical properties except for special tests described below. E', tangent tangent, in mathematics. 1 In geometry, the tangent to a circle or sphere is a straight line that intersects the circle or sphere in one and only one point. delta Dynamic complex tension modulus See modulo. and tangent delta were measured on a viscoelastic Adj. 1. viscoelastic - having viscous as well as elastic properties natural philosophy, physics - the science of matter and energy and their interactions; "his favorite subject was physics" spectrometer spectrometer Device for detecting and analyzing wavelengths of electromagnetic radiation, commonly used for molecular spectroscopy; more broadly, any of various instruments in which an emission (as of electromagnetic radiation or particles) is spread out according to some . Test conditions were 10 Hz frequency, 2% deflection deflection /de·flec·tion/ (de-flek´shun) deviation or movement from a straight line or given course, such as from the baseline in electrocardiography. de·flec·tion n. 1. at 15% extension from minus 100 to plus 100 [degrees] C. Oil migration During continuous copying, oil in paper feeding rolls can gradually migrate from the roll surface to the paper. As a result, the diameter of the .roller decreases, causing feed problems. We evaluate migration of oil via the use of a compression set measuring apparatus, as shown in figure 1. Ten sheets of paper are put above and under a rubber compression set test piece and compressed 25% under the conditions of 23 [degrees] C for 72 hrs. The amount of oil migration is then measured via the change in weight of the roller and is converted to a relative index. [Figure 1 ILLUSTRATION OMITTED] Bloom and bleed Printing at the very edge of the paper. Many laser printers, including all LaserJets up to the 11x17" 4V, cannot print to the very edge, leaving a border of approximately 1/4". In commercial printing, bleeding is generally more expensive, because wider paper is often used, which is later One of the most frequent problems during paper feeding is with surface bloom or oil bleed from the roll. An accelerated test of bloom and bleed was conducted under several conditions. Roller samples were hung in a test chamber under a successive eight-cycle test. One cycle consists of three individual exposure tests. The first step condition is 70 [degrees] C at 95% relative humidity relative humidity n. The ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperature, expressed as a percentage. (RH) for one hour, the second is 23 [degrees] C at 50% RH for one hour and the third is 10 [degrees] C, 20% RH for one hour. After eight cycles, evaluations were made on surface appearance. The rollers were then installed in the paper feeding test equipment to test paper feeding ability of the aged rollers. Paper feeding test In order to evaluate the paper feeding ability of rollers during high volume copying, we constructed a paper feeding test machine which can continuously feed 3,500 sheets of paper. NPR NPR In currencies, this is the abbreviation for the Nepal Rupee. Notes: The currency market, also known as the Foreign Exchange market, is the largest financial market in the world, with a daily average volume of over US $1 trillion. pick-up paper feeding rollers were made by compression molding Compression molding is a method of molding in which the molding material, generally preheated, is first placed in an open, heated mold cavity. The mold is closed with a top force or plug member, pressure is applied to force the material into contact with all mold areas, and heat using molds with a special embossed em·boss tr.v. em·bossed, em·boss·ing, em·boss·es 1. To mold or carve in relief: emboss a design on a coin. 2. surface which simulates that of a ground roller Noun 1. ground roller - Madagascan roller with terrestrial and crepuscular habits that feeds on e.g. insects and worms roller - Old World bird that tumbles or rolls in flight; related to kingfishers . Cure conditions of the roller were at 160 [degrees] C for 10 minutes. For comparison, a commercially available EPDM roller (Shore A 37) was also evaluated. Two kinds of paper were used in our evaluation because paper type is suspected to affect feeding performance. Paper-pulling force of the roller was measured with a strain gauge strain gauge Device for measuring the changes in distances between points in solid bodies that occur when the body is deformed. Strain gauges are used either to obtain information from which stresses in bodies can be calculated or to act as indicating elements on devices for every 10,000 sheets. The amount of roller abrasion was evaluated by weighing roller before and after 10,000 sheets. Evaluations were also made on the surface appearance of the rolls for paper dust pollution under a microscope. Results and discussion Quality function deployment Quality function deployment or "QFD" is a flexible and comprehensive decision making technique used in product or service development, brand marketing, and product management. Paper feeding rollers are installed for picking up the papers from the paper stock tray and sending towards the photo-conductor. Table 1 gives a brief explanation of the relationship between the original property requirements of the rubber paper feeding roller as dictated by the copy machine industry. The general requirements outlined in this table provide the basis for the development of compounds for paper feeding rollers. Some requirements are not directly related to the copy performance but are requirements during paper stock transportation. Reliability requirements are classified into three ranks as A (most important), B (more important) and C (important). Principal physical properties required for paper feeding rollers are low hardness, high rebound rebound (rē´bownd), n/v 1. a recovery from illness. n 2. an outbreak of fresh reflex activity after withdrawal of a stimulus rebound adjective , high abrasion resistance and high friction coefficient. Of lesser importance is that the roll be bloomless and bleedless within the operating temperature of the copy machine. This is commonly specified from 10 to 40 [degrees] C.
Table 1 - quality function deployment
Requirement Measurable characteristics
Priority Tensile Modulus
strengths
Feedability
Elasticity A D
Soft A E
High friction A
Longer life
Constant friction A
Constant roll diameter B
Paper dusts adhesion A
Wider operating temp.
Feedability at 10 [degrees] C B
Copy quality
Print uniformity A
Less noise C
Stability during stock C
Friction
Requirement Hardness Rebound coefficient
Feedability
Elasticity E D
Soft D E
High friction D D
Longer life
Constant friction D
Constant roll diameter
Paper dusts adhesion
Wider operating temp.
Feedability at 10 [degrees] C D
Copy quality
Print uniformity E
Less noise D E
Stability during stock
Cold Heat
Requirement Abrasion resistance resistance
Feedability
Elasticity D
Soft E
High friction
Longer life
Constant friction D D D
Constant roll diameter D
Paper dusts adhesion
Wider operating temp.
Feedability at 10 [degrees] C D
Copy quality
Print uniformity
Less noise
Stability during stock
Ozone
Requirement Bloom Bleed resistance
Feedability
Elasticity
Soft
High friction E E E
Longer life
Constant friction D D E
Constant roll diameter E
Paper dusts adhesion E E
Wider operating temp.
Feedability at 10 [degrees] C E
Copy quality
Print uniformity E D
Less noise
Stability during stock D D E
(D) Strong relation; (E) weak relation Priority rating: (A) - most important; (B) - more important; (C) - important Properties of PNR Polynorbornene is the common name of polymers obtained by the homo-polymerization of bicylo(2.2.1)hept-2-ene or 2-norbornene. The chemical structure and typical properties are given in table 2. PNR is characterized char·ac·ter·ize tr.v. character·ized, character·iz·ing, character·iz·es 1. To describe the qualities or peculiarities of: characterized the warden as ruthless. 2. by an unusually high molecular weight (2 million gram/mole) and a glass transition temperature The glass transition temperature is the temperature below which the physical properties of amorphous materials vary in a manner similar to those of a solid phase (glassy state), and above which amorphous materials behave like liquids (rubbery state). of 35 [degrees] C. It, therefore, can be regarded as an intermediate between elastomers and thermoplastics. Polynorbornene has a very high affinity for liquid hydrocarbons hydrocarbons (hīˈ·drō·kärˑ·b  nz),n. as promoted by its porous porous /por·ous/ (por´us) penetrated by pores and open spaces. po·rous adj. 1. Full of or having pores. 2. Admitting the passage of gas or liquid through pores. structure. Because of its compatibility with oils that act as a plasticizer plas·ti·ciz·er n. Any of various substances added to plastics or other materials to make or keep them soft or pliable. plasticizer or -ciser Noun , the glass transition temperature of the polynorbornene/oil mixture can be lowered to -60 [degrees] C. The amount of plasticizer included in a compound determines the softness of the vulcanizate. Very low hardness values down to 10 Shore A can be reached with amazingly good mechanical properties. The type of plasticizer used affects the cold resistance and rebound properties of the final compound. The presence of double bonds in the polymeric polymeric /poly·mer·ic/ (pol?i-mer´ik) exhibiting the characteristics of a polymer. pol·y·mer·ic adj. 1. Having the properties of a polymer. 2. chain allows vulcanization vulcanization (vŭl'kənəzā`shən), treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance to solvents, and to render it impervious to moderate heat and cold. with common peroxides or sulfur cure systems.
Table 2 - raw polymer characteristics
Composition Polynorbornene
Appearance White powder
Particle size Between 0.05 and 1mm
average 0.3-0.4mm
Molecular weight More than 2 million
Glass transition temp. 35 [degrees] C
Apparent density 0.30
Specific gravity 0.96
Solubility parameter value 8.09
Solubility Insoluble in water, alcohol.
Easily soluble in aromatic,
naphthenic and paraffnic oils.
Cured extended PNR Figure 2 exhibits the relationship between hardness and tensile strength of PNR in comparison with other elastomers. It is shown that the tensile strength of highly oil extended PNR is much higher than that of other elastomers of equivalent hardness. In general, very low hardness compounds show inferior processability because of their low viscosity, but the very high molecular weight of PNR gives the plasticized compounds sufficient viscosity for trouble-free use. [Figure 2 ILLUSTRATION OMITTED] Figures 3-6 show the effects of type and volume of oil added to the PNR compound on hardness, tensile strength, rebound and compression set. [Figures 3-6 ILLUSTRATION OMITTED] Ozone resistance Because of the presence of double bonds in the chain of PNR, unprotected PNR vulcanizates have limited resistance to ozone. Non-staining compounds with improved ozone resistance can be obtained by adding 20 to 30 parts EPDM, though this will mean a slight drop in mechanical properties. Table 3 shows the changes in mechanical properties and ozone resistance in relation to the ratio of EPDM added. Table 3 - ozone resistance of PNR/EPDM blend Formulation A B C D PNR 100 80 70 60 EPDM(*) 0 20 30 40 Zinc oxide 5 5 5 5 Stearic acid 1 1 1 1 FEF black 200 200 200 200 Aromatic oil, low viscosity 180 180 180 180 Paraffinic oil 20 20 20 20 CBS 5 5 5 5 Sulfur 1.5 1.5 1.5 1.5 Original properties Tensile strength (MPa) 16.1 11.6 9.1 7.1 Elongation (%) 340 260 220 200 Hardness (Shore A) 52 53 55 55 Compression set (%) 15 14 14 11 Ozone resistance At 50% elongation 2 7 24 >200 At 40% elongation 2 9 48 >200 At 30% elongation 2 9 146 >200 At 25% elongation 2 48 >200 >200 At 20% elongation 2 48 >200 >200 At 10% elongation 3 >200 >200 >200 Time to initial crack observed (hour) (*) EPDM with 9% unsaturation un·sat·u·rat·ed adj. 1. Of or relating to an organic compound, especially a fatty acid, containing one or more double or triple bonds between the carbon atoms. 2. Capable of dissolving more of a solute at a given temperature. and 55% ethylene ethylene (ĕth`əlēn') or ethene (ĕth`ēn), H2C=CH2, a gaseous unsaturated hydrocarbon. It is the simplest alkene. Rebound The glass transition temperature of PNR is higher than that of other elastomers. Because of the compatibility of PNR with oil, highly oil extended PNR compounds exhibit extremely low glass transition temperatures. Figures 7-9 illustrate the temperature dependence of rebound on the type, viscosity and amount of oil respectively. These results show that compounds containing naphthenic or paraffinic oil exhibit high rebound within the operating temperature of the copy machine. [Figures 7-9 ILLUSTRATION OMITTED] Physical properties Table 4 shows the paper feed roller formulation formulation /for·mu·la·tion/ (for?mu-la´shun) the act or product of formulating. American Law Institute Formulation of PNR and EPDM used in this study. Table 5 shows the original properties of PNR and EPDM measured at 23 [degrees] C. PNR shows higher tensile strength than EPDM in spite of a lower hardness by 10 points. Ozone tests were conducted under the conditions of 40, 50 pphm, 72 hrs. and 30% elongation elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the planet as measured from the earth. . PNR compounds which contained 30 phr EPDM showed good ozone resistance. The conditions of Akron abrasion test are 6 lb., 10, 1,000 revolutions and the abrasion loss is converted to index. Abrasion tests show PNR is better than EPDM despite its lower hardness.
Table 4 - formulations of PNR and EPDM roller
Norsorex Phr EPDM Phr
PNR 100 EPDM 100
Naphthenic oil 175 Paraffinic oil 90
EPDM 30 Active zinc oxide 3
Zinc oxide 5 Stearic acid 1
FEF carbon, N-550 1 Silica 20
Silica 20 Clay 20
Titanium dioxide 40 FEF carbon, N-550 1
Irganox 1520 D 1 Titanium dioxide 8
Sulfur 2 Silane coupling agent 1.5
TMTD TOT-N 6 Sulfur 1.5
1 TMTD 0.5
MBTS 1.5
ZnBDC 0.5
MBTS 0.5
Table 5 - physical properties of PNR and EPDM
Original properties PNR EPDM
Tensile strength (MPa) 8.0 6.5
Elongation (%) 490 460
300% modulus (MPa) 0.7 1.2
Hardness (Shore A) 24 35
Compression set (%) 24 25
Rebound (%)
At -10 [degrees] C 40 50
At 0 [degrees] C 6O 6O
At 10 [degrees] C 73 68
At 23 [degrees] C 78 70
At 35 [degrees] C 78 70
Ozone resistance no crack no crack
Akron abrasion, index 270 100
Migration test, index 106 100
Temperature dependence of hardness, rebound and dynamic properties Figures 10-12 show temperature dependence of hardness, rebound and dynamic properties of the PNR compounds. Hardness above 0 [degrees] C is almost constant. The PNR compound shows high rebound and little change within the operational temperature range of the copy machine (about 10 to 40 [degrees] C). From the result of viscoelasticity Viscoelasticity, also known as anelasticity, is the study of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like honey, resist shear flow and strain linearly with time when a stress is applied. , the dynamic properties of this compound are almost constant above 0 [degrees] C. [Figures 10-12 ILLUSTRATION OMITTED] Oil migration Table 5 shows the result of the oil migration test. Compared with EPDM, the PNR compound shows the same amount of oil migration in spite of the higher oil content of the PNR compound. Compatibility of PNR with naphthenic oil is better than that of EPDM. Bleed and bloom After the eight-cycle accelerated test of bleed and bloom, the surface of rollers was observed. No bleed and bloom was observed on the surface. Figures 13 and 14 show the test results of abrasion loss and paper pulling force, respectively. Accelerated bleed and bloom test didn't give rise to the problem of paper feeding. Though the PNR roller compound contains a large volume of oil, bleed and bloom do not occur because of its exceptional compatibility with oil. [Figures 13-14 ILLUSTRATION OMITTED] Paper feeding test Figure 15 shows the relationship between paper pulling force and the number of sheets of paper fed. Evaluations were conducted using two kinds of paper. Pulling force was stable up to 40,000 sheets for the two kinds of paper. For Kangas paper, we evaluated the PNR roller up to 100,000 sheets and a decrease of pulling force was not observed. [Figure 15 ILLUSTRATION OMITTED] Abrasion Figure 16 shows the relationship between abrasion loss and number of sheets fed and indicates that abrasion is almost proportional to sheets fed up to 40,000 sheets. Compared with the EPDM roller, the PNR roller shows slightly better abrasion resistance in spite of the fact that the hardness of the PNR roller is 10 points lower than the EPDM roller. For Kangas paper, the PNR roller was tested up to 100,000 sheets and its abrasion is also proportional to the number of sheets fed. [Figure 16 ILLUSTRATION OMITTED] Paper dusts adhesion adhesion /ad·he·sion/ (ad-he´zhun) 1. the property of remaining in close proximity. 2. the stable joining of parts to one another, which may occur abnormally. 3. During large volume copying, paper dust generated tends to adhere to the surface of the roller. Evaluations were made on the surface appearance of the rollers as magnified under a microscope. Dust was observed on the surface of the EPDM roller after the passage of just 20,000 sheets. The surface of the PNR roller shows less paper dust adhered even up to 100,000 sheets. The surface of PNR roller is less sticky because of the very high molecular weight of PNR. Paper dust on the surface of the roller can often cause mis-feeds by paper slippage Slippage The difference between estimated transaction costs and the amount actually paid. Notes: Slippage is usually attributed to a change in the spread. See also: Spread, Transaction Costs Slippage between roller and paper. Summary and conclusions We evaluated the paper feeding ability of a PNR roller vs.an EPDM roller used in paper feeding machines. * The PNR roller shows equal or better feeding performance than the EPDM roller in spite of lower hardness by 10 points. * The PNR roller exhibits better pollution resistance to paper dust generated during the large volume copying over the EPDM roller. * The PNR roller compound exhibits superior physical properties over other low hardness compounded elastomers. As the data reported, it is becoming clear that highly oil extended PNR compounds show the best performance balance for paper feeding rollers. This is further verified in the trend for PNR compounds to be specified for paper feeding rollers in most all of the plain paper copy machines in Japan. The typical properties of highly oil extended PNR compounds may be summarized as follows: * Very low hardness, high tensile strength, high coefficient of friction coefficient of friction n. pl. coefficients of friction The ratio of the force that maintains contact between an object and a surface and the frictional force that resists the motion of the object. and high abrasion resistance; * freely controllable rebound over the wide range of temperatures with the combination of these properties, PNR polymers are widely used for many applications outside that of roller applications. References (1.) Keiji Toyoda; Polyfile 34, No. 402, (1997). (2.) Data Supply; Toner An electrically charged ink used in copy machines and laser printers. It adheres to an invisible image that has been charged with the opposite polarity onto a plate or drum or onto the paper itself. market, edition 1997/1998 (1997). (3.) Keiji Toyoda; Gomu Roller Seminar, Technosystem, 19 December (1997). Kinro Hashimoto, Keiji Toyoda and Yoshi Wada Yoshi Wada (surname Wada; born Yoshimasa Wada, Japan) is a sound installation artist and musician living in the United States. He lived in New York for many years but now lives in San Francisco, California. , Nippon Zeon Co., and Mark Peachey and Terutaka Yao, Zeon Chemical Inc. |
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