FR2473742A1 - EXPANDER FUSION ROLL AND METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

Disclosed is a developer fuser roll and a method of making it. The roller is formed from a compound formed from a silicone elastomer and containing as additive a silicone oil, such as polydimethyl-siloxane oil, of high viscosity, that is to say at least 1000 centistokes, and further a curing agent, the content of which is maintained at about 10 parts per 100 parts of silicone elastomer and silicone oil, the proportion of oil to the elastomer itself being from 5 to 50 parts per 100 parts of elastomer. Application to electrostatic copying machines. (CF DRAWING IN BOPI)

Description

Developer melting roll and its manufacturing process The phase

  The final operating procedure in a conventional electrostatic copying machine is the fixing or melting of the developer powder image on the paper substrate. The developer is a pigmented thermoplastic material that must be heated above its softening point to create particle-on-particle and particle-on-paper adhesion to produce a permanent copy. Silicone rubber fusion rollers are typically used in this process. The melt roll is typically one of two nip rolls between which the developer image-carrying paper sheet is passed during the fusing or fixing process. The melting roll is

  typically a silicone rubber roll. In function

  design of the electrostatic copying machine

  In particular, the two nip rolls may be formed of silicone rubber or one of the rollers may be a silicone rubber and the other may be a

  steel roller or a steel roller coated with poly-

  Tetrafluoroethylene (PTFE). The rubber melting roller

  silicone rubber and / or the other roll of a pair of rolls

  nip can be heated directly or indirectly and the melt roller can contact the front side of the sheet of paper on which is

  placed the developer or with its reverse side.

  Regardless of the particular configuration

  of using a melting roll in a donating machine.

  The silicone rubber melting roll comes into contact, either directly or indirectly, with the developer. The developer must be detached from the roll of

  merged with each copy execution so that the copy

  vante cleanly undergoes the merger operation. That is,

  say that, if the developer has not been properly removed

  of the fusing roll, the next copy made by the

  China will receive traces of developer remaining on the melting roll and will then become fouled, scrambled or otherwise damaged. This problem of developer adhesion resulting in faulty copying is sometimes referred to as "smearing." Smearing is not the only cause of incidents with a fuser roller, for example, gripping fingers can damage the roll, or

  although this one can be affected by a warm-up. This-

  during, smearing is one of the main factors of malfunction of the melting roller and often limits its service life. Accordingly, the duration of the intended use period for a melt roll is often measured by the number of copies that can be made by the melt roll before the developer detaches incorrectly, i.e. the adhesion of the developer particles to the silicone rubber melting roll does not reach a degree

unacceptable.

  A common practice in solving the problem of smudging is to create a thin film of silicone fluid on the outer surface of the smear roll

  to facilitate the detachment of the developer particles.

  This problem has been solved in the known domain by incorporating

  a relatively low viscosity silicone fluid

  (about 100 cs) to the silicone rubber compound

  storing the melt roll. A thin film of silicone fluid is formed on the outer surface of the fusing roll as a result of fluid migration through the rubber to the surface of the roll. This works satisfactorily as long as a silicone fluid coating appears on its surface. The degree of migration of this low viscosity silicone oil is such that the roll is depleted of oil relatively quickly and an oil refill is required. For example, a manufacturer of electrostatic copying machines specifies

  that the roll of fusion must be changed after 50,000 copies.

  Although other causes of tampering with said roll may be taken into account for the establishment of this

  value, an essential factor is that food

  The silicone oil content of the roll is reduced to a level such that the adhesion of the developer particles to the

  roll is likely to occur after approximately 50,000

  Magpies. The obligation to replace the fuser roller due to smudging is obviously a factor in the operation of copying machines that manufacturers and

  users would be happy to see reduce in frequency.

  That is, it is quite desirable to extend the service life of the fusing rolls by increasing the number of copies that can be made before the smudging is difficult and that is why The purpose of the invention is to provide a melting roll and its method

  of manufacture, with a view to solving this problem.

  According to the invention, there is provided a melt roll comprising a cylindrical body formed of a silicone elastomeric material to which is incorporated a high viscosity silicone oil, namely a viscosity of at least 1000 centistokes (cs). More particularly,

  an oil consisting of polydimethylsiloxane of a screw

  cosity of about 1,000 cs (about 20,000 MW) is incorpo-

  to the silicone rubber compound of the melting roll. Incorporation of this high viscosity oil

  produced a very large increase, which was also unexpectedly

  tense, service life of silicone rubber fusion rollers before particle detachment

  developer is a problem. Fusion rollers

  Bricks according to the present invention have an estimated useful life of several hundreds of thousands of copies in some cases before the developer begins to adhere to the roll. The polydimethylsiloxane oil is incorporated in the silicone rubber in the proportion of 50 parts per part of rubber.

  The invention also relates to a method of manufacturing

  of a rubber melting roll consisting of

  form a mixture containing from 99 to 101 parts of an elastomer

  silicone, 8 to 20 parts of a curing agent, 5 to 50 parts of a silicone oil with a viscosity of not less than 1,000 cs, and casting the mixture in a

  mold and then harden it to form a roll.

  Other advantages and characteristics of the

2 47374a -4-

  will be highlighted later in the description of the

  FIG. 1 is a perspective view of a silicone rubber melting roll according to the present invention, and FIGS. 2 and 4 are a non-limiting example with reference to the accompanying drawings, in which: FIG. 3 show one of the arrangements

  typical known for using a rubber melting roller.

silicone bunch.

  In the drawings, Figure 1 shows the configuration

  general application of a silicone rubber

  cone, designated as a whole by 10. This roller has a central metal axis on which is fixed a layer

  external cylindrical 14 of a silicone elastomeric material.

  Since the subject of the present invention relates to the composition of the silicone material that forms the melt roll, as well as the improved roll thus obtained,

  specialists in the subject will understand that the external aspect

  the roller according to the invention does not differ from that of a roll of known type. As is admitted for the

  known rolls, the roll according to the invention is preferably

  made in a well polished surface mold, using low shrinkage materials. The use of a high degree of polishing of the mold makes it possible to obtain on the outer surface of the roll a perfect finish without having

  to perform a finishing grinding operation, i.e.

  say a grinding operation after molding the roll.

  Making the roll in the appropriate mold includes

  the following operations: (1) positioning of the central axis

  tral of mandrel 12 into mold, (2) filling of mold with uncooked silicone compound, (3) baking of roll

  at about 1000C for about fifteen minutes and (4) post-

  baking in an oven for about two hours at 205 OC.

  In Figures 2 and 3, it is shown schematically

  the typical installation of a fusion roll 10 which constitutes one of the two rolls of nips, the other of which

  is in this case a metal cylinder whose surface ex-

  dull is provided with a polytetrafluoroethylene coating.

  In the configuration of Figures 2 and 3. the rollers 10-5 and 16 rotate in opposite directions, i.e. in the directions indicated by arrows, to draw a sheet of paper 18 in the inter-roll gap. The surface of the sheet 18 in contact with the roller 16 carries an electrostatically formed developer image. The unfused developer particles are indicated by the point segment 20 to the left of the roll gap, while the melted developer particles are indicated by the solid line 22 to the right of the roll gap. The developer particles

  melted by heating one or both of the two

  10, 16 when the sheet of paper passes through the

  existing valley between them. The training of these particles,

  indicated in the form of flattened and partly

  melted on the surface of the roller 16, is undesirable.

  due to the fact that they contaminate the surface of said roll 16 (that is, the surface of the roll tends to become fouled). In order to try to keep clean the

  surface of the roll 16, a cleaning strip 16 is presented

  both in the form of a continuously rotating belt

  naked, can be brought into contact with the surface of the roller 16 to exert on it a scraping action. However, any residual developer particles on said surface are not removed by the cleaning tape 26. Some particles continue to adhere to the surface of the roll 16 and are transferred onto the roll in a soiling process, which is called "smearing" as shown in Fig. 3. If the surface of the silicone material roll 10 retains the developer particles

  thus arriving on it, this roll becomes clogged with

  then stains on the reverse side of the next sheet of paper passing between the rolls

  or the rollers pass the particles of

  backwards and forwards in repeated phases.

  stains so that both sides of the leaves

successive are fouled.

  As mentioned above, the configuration

  2 and 3 correspond only to one of the possible arrangements using silicone elastomer melting rollers to form one of the nip rollers operating in the melting station. However,

  the problem posed by the adhesion of the particles of

  It has been a permanent problem on the surface of silicone rollers that has limited the service life of the melters of most machines. Fusion rolls of known types have been

  typically provided with a low viscosity silicone oil

  cosity (of the order of 100 to 250 cs) to encourage the

  the developer particles compared to the

  roll face. This result, i.e., promoting detachment of the developer particles from the roll surface, was achieved by forming a thin film of low viscosity silicone oil on the outer surface of the roll. In some applications of the known domain,

  this film was formed by directly depositing the silicone oil

  cone of low viscosity on the surface of the roll then

  that, in other embodiments, the silicone oil

  cone of low viscosity has been incorporated into the

  making the roll, the oil propagating towards the over-

  However, once the oil is consumed, it is necessary to replace the roller or, in certain cases, it can be carried out.

  state to recreate the film of oil.

  It has also been found that the service life of silicone rubber fusion rollers can be extended considerably in order to produce several

  hundreds of thousands of copies in some cases,

  so much of the currently accepted practice. More specifically, it has been discovered that the incorporation of a very high viscosity silicone oil into the material of which

  the melting roll is made produces a strong elongation

  the service life of this roller. An amount

  of polydimethylsiloxane oil with a higher viscosity

  greater than 1,000 centistokes (approximately 20,000 MW)

  has been incorporated into the compound of which the roll is made.

  This polydimethylsiloxane oil was found to propagate to the surface of the melt roll to form a satisfactory film which favored detachment of the developer particles. In addition, it was found that the degree of migration of this high viscosity oil was synergistically lower than would have been expected simply because of the viscosity difference between the high viscosity oil used in the case considered.

  and the low viscosity oil used in the prior art.

  It appears that since the poly-

  dimethylsiloxane (1,000 cs) are much larger than those of the known type of silicone oil <100 cs), the large molecules of polydimethylsiloxane intertwine in fact the

  with each other and with the rubber molecules

  silicone bunch of the roll. This apparent molecular interleaving not only causes a sharp decrease in the degree of diffusion of the silicone oil but also promotes the retention of an effective film on the surface of the roll. This results in a significant and synergistic increase in the service life of the roll, both by improving the retention of an effective release film of silicone oil on the surface of the roll and

  by establishing a degree of migration of silicone oil

  cone which is much smaller than in the prior art,

  but which is still appropriate for keeping the film neces-

on the surface of the roll.

  It should be noted that while the theory of molecular interleaving is believed to explain

  correctly and to understand the reasons for

  unexpected results obtained by the invention, it is not certain that the theory is correct and we do not want

to be bound to this theory.

  High viscosity silicone oil used

  in the present invention consists of linear polymers

  Dimethylsiloxane res of the type [(CH 3) 2 SiO] x x is an integer greater than 2, and having the following unit structure CH 3

-if-o-

  CH3 The composition or specific structure of the silicone base elastomeric material is not within the scope of the invention. On the contrary, it should be noted that

  may use in the present invention any elastic material

  silicone spinner suitable for the manufacture of fusion rollers. The silicone base elastomeric material may be of the type where the vulcanization is carried out by energy-activated hardening or it may be of the

  vulcanization at room temperature (RTV). According to the

  polydimethylsiloxane (PDMS) oil is not newton-

  High viscosity oil (about 1,000 cs or more) is incorporated into the silicone elastomer compound from which the melt roll is made in the proportion of from 50 to 100 parts of the silicone elastomer.

basic.

  A particularly advantageous composition in the practice of the invention is given below:

Table 1

  Materials Weight (g) Silicone elastomer (1) 100 Hardener (2) 13 PDMS oil (> 1.000 cs) (3) Iron oxide powder 1

  These ingredients were mixed together, the mixture was poured

  in a mold and hardened to form a rou-

  silicone type melting water of the general type shown in Figure 1. This melt roller was installed

  in a Royal RBC II electrostatic copying machine.

  According to the manufacturer, the service life of the

  (1) Polydimethylsiloxane elastomer "Silastic J-RTV" (70,000 cs), manufactured by Dow Corning,, (2) "Silastic J-PDMS" curing agent associated with groups

  functional groups for crosslinking and a catalyst

  Tine, manufactured by Dow Corning, (3) Polydimethylsiloxane oil DC200 (1,000 cs, 20,000 MW),

manufactured by Dow Corning.

  - 9 - known silicone rubber melting agents (impregnated with low viscosity silicone oil) in

  this machine was of the order of 50,000 copies. The rou-

  the melting water according to the invention has worked in this machine so as to produce more than 250,000 copies

  without any problem of detachment from disclosure

  tor. Tests have also shown that

  establish a useful range of proportions of the ingredients

  in the compound of Table 1, as shown below:

Table 2

  Material Silicone elastomer Hardener PDMS oil (7 1,000 cs) Iron oxide powder Weight (g) + 1

13 + 7

+ g

1 + 19

  - 0.5 These ranges of proportions were established following the following test. Eleven compounds having

  the compositions shown in Table 3.

  Table Materials Silicone Elastomer Curing Agent PDMS Oil (7 1.000 cs) Iron Oxide Powder Siloxane Elastomer Hardener Agent PDMS Oil Iron Oxide Powder

1 1 1 1 1 1 1

7 8

100

11 12

20

1 1 1 1 1

  Each of these eleven test samples was

  manually dipped, degassed, cast as pulling plates 152 x 152 x 2.54 mm, cured at 70 ° C for 30 minutes

- 10 -

  minutes, post-cured for 24 hours at room temperature and cut into sample strips of 4 x 152 mm. The fully hardened strips were sprinkled with developer powder and placed in an oven at 1000C for five minutes, then removed from the oven and allowed to cool to room temperature. A metal spatula was then used to try to detach the developer. With sample No 1

  (no PDMS oil), the developer did not come off.

  The releasability of the developer has increased in

  its direct from the amount of PDMS oil incorporated.

  In these tests, the samples were first prepared

  Nos. 1 to 6. It should be noted that the mechanical properties

  sample tapes decreased in samples.

  Nos. 4, 5 and 6 as the amount of PDMS oil has increased to more than twenty parts per hundred parts. Samples Nos. 4 to 6 were significantly lower than samples 1 to 3 with respect to tear and tensile strength characteristics. This is believed to have occurred because the amounts of PDMS oil were sufficient to dilute the curing agent and to reduce the probabilities of crosslinking between this material.

  hardener and silicone elastomer. In corres-

  samples 7 to 11 were carried out in addition to

  as an additional amount of curing agent in all cases so as to further involve one curing agent portion per ten parts of PDMS oil in order to maintain the overall proportions of ten parts curing agent per hundred parts of curing agent. Silicone elastomer and PDMS oil. Samples Nos. 7 to 11 gave

  acceptable results, as regards the characteristics

  tensile strength and tear resistance, these

  results are comparable to those of samples 1 to 3.

  Accordingly, it has been determined that the amount of high viscosity PDMS oil to be added to a silicone elastomer compound should be limited to about twenty parts per hundred parts of silicone elastomer, unless the amount of silicone elastomer compound is increased. hardener to maintain a ratio of about ten parts hardener to

- he -

  hundred parts of silicone elastomer and poly-

  dimethylsiloxane of high viscosity. It should be noted that the additional amount of curing agent incorporated in the system should not produce any significant curing of the high viscosity polydimethylsiloxane oil which is

  added since this oil is essentially non-reactive

  tive. Additional tests similar to those in Table 3 have also been made to prepare compounds containing less than ten and more than fifty parts of high viscosity polydimethylsiloxane oil for

  one hundred parts of silicone elastomer. These tests have

  (1) that it was necessary to involve a mini-

  of five parts of this PDMS oil per hundred parts of elastomer to obtain a significant detaching effect of the developer and (2) it was necessary to limit the amount of additional PDMS oil to less than fifty parts per hundred parts of silicone elastomer for

  prevent oil from oozing and forming a colloidal surface

unacceptable laceration on the roll.

  It has also been determined that the content of curing agent should be between eight and twenty parts per hundred parts of silicone elastomer. Less than eight parts produce insufficient hardening and more

  twenty parts produce a hardening too fast.

  As noted above, melting rolls made in accordance with the present invention

  have a long service life. It is-

  that is, these rolls are capable of making several hundred thousand copies before the developer detachment (or conversely the undesirable adhesion of the

  revealing on the roll) does not pose any

  reinstatement or roll replacement.

- 12 -

R E V E N D I C AT IONS

  1. - Melt roll characterized in that it comprises a substantially cylindrical body of silicone elastomeric material, and in that a suitable amount of high viscosity silicone oil is

  incorporated in said elastomer body (14), the screw

  cosity of said silicone oil being at least 1,000 centistokes. 2. - melting roll according to claim 1, characterized in that the amount of silicone oil of high viscosity is between 5 and 50 parts for

  parts of silicone elastomeric material.

  3. - Fusion roll according to one of the

  1 and 2, characterized in that said

  silicone is polydimethylsiloxane.

  4. Roller for use in material handling equipment, characterized in that it comprises a body of rubberized material having the following composition: Ingredients Weight (parts) Silicone elastomer 99-101 Hardener agent 8-20 Silicone oil ( 71,000 cs) 5-50

  5. Roller according to claim 4, characterized

  in that the content of curing agent is maintained in the ratio of about 10 parts of curing agent per 100 parts of silicone elastomer and silicone oil.

  6. - Roller according to one of claims 4

  or 5, characterized in that said elastomer is an elastomer

  polydimethylsiloxane mill and in that said oil

  is polydimethylsiloxane oil.

  7. Roller according to any one of the

  4 to 6, characterized in that the composition

  holds from 0.5 to 1.5 parts of iron oxide powder.

  8. Roller according to any one of the

  cations 4 to 7, characterized in that the composition is approximately the following: 247374e

- 13 -

  Ingredients Weight (parts) Silicone elastomer 100 Hardener 13 Silicone oil (<1,000 bones) 9. Roller according to Claim 8, characterized in that it contains about one part of powder

of iron oxide.

  10. - A method of manufacturing a roll of rubberized material, characterized in that it consists in preparing a mixture containing from 99 to 101 parts of a

  silicone elastomer, from 8 to 20 parts of a hardening agent

  5 to 50 parts of a silicone oil having a viscosity of not less than 1000 bones, then pouring this mixture into a mold and curing it to form a

roller.

  11. The process according to claim 10, wherein

  in that the mixture preparation phase con-

  add 0.5 to 1.5 parts of iron oxide.

  12. The process according to claim 10, wherein

  in that the mixing preparation phase con-

  is also to maintain the hardening agent in the

  portion of about 10 parts of hardener per 100

  parts of silicone elastomer and silicone oil.

  13. - Process according to any one of the

  10 to 12, characterized in that the silicone elastomer is a polydimethylsiloxane elastomer and

  what the silicone oil is polydimethyl

siloxane.

  14. - Method according to claim 13, characterized

  in that the mixture preparation phase con-

  form a mixture containing about 100 parts silicone elastomer, 13 parts hardener

* and 30 parts of silicone oil.

  15. - Process according to claim 14, characterized

  in that the mixture preparation phase con-

  is also to add about a part of powder

of iron oxide.