DE2363346B2 - Fuser roller with silicone elastomer coating - Google Patents

Description

-Si-O-CH ₈

transferred so that it can be softened enough to be permanently fixed on the paper, ao Preferably, the elastic or deformieröare in general The roller is heated and the pressure roller is rigid.

They are heated fusing rollers with silicone, where η is an integer and between 3 and 8 known elastomer coating, which in some amounts to. 35 cases are still stored in wrappings

3. A method of making a siioxane ring formed according to a low surface energy material that does not contain any of the preceding claims. Furthermore, from the US-PS fusing roller with a cylindrical roller 36 69 707 the problem is known that after the fusible core, which is uniformly coated with a silicone elastomer process on the one hand, the toner is not coated on the heated one and in which the silicone elastomer 30 roller, but adheres to the paper, and to form a silicone rubber layer vulcani- other the paper is easily siert from the heated roller, characterized in that core and dissolves and does not stick to this heated roller coating to a temperature that at least remains and with it on the wrong path transported away from the normal operating temperature of the melting point. To solve this problem, the pre-fixing roller is heated and beating on it, the temperature is kept in the silicone elastomer coating so that the roller and its energy can be stored at the same time as filling materials that have low surface areas of the temperature effect. As such a filler material is stratified there is exposed to a vacuum, which is proposed, for example, polytetrafluoroethylene. It is sufficient to determine the boiling point of the volatile grains, it is also known to use rollers with materials to beponenten the silicone elastomer below the pre-40, which lower the temperature prevailing a slightly higher surface energy, and the roller an anti-adhesive agent in liquid temperature And the effect of vacuum so long to supply the influence of the higher energy levels, until the temporal derivation of the table materials compensate again and thus the weight loss to improve the non-stick properties at a constant temperature,
and constant pressure, essentially constant 45 The possible sticking and the associated is possibility for the copy material with the heated

[</ (Weight loss) / df = K]. Role to run along and not in the normal way

Breaking away from this role are the main problems encountered with this technique. Silicone rubbers are

50 materials that have the property only one very

have low surface energy so that they are advantageously used in this application can. However, silicone rubbers have properties

The present invention relates to a fuser roller having a wide range of practical use Finer coating made of a silicone elastomer for 55 as a coating material for heated fusion-fused in Electro-photographic device for melt rolling are unsuitable. The silicone rubbers have one fixing of thermoplastic material on a very low surface energy at room temperature, Carrier. However, if they are at the elevated temperatures in the

There are various techniques known to be used in thermal operation as fuser roller coating plastic powder, also known as toner, on a 60, then the non-stick properties of the SiIi carrier, such as paper, melted or congums almost completely disappeared, so that to fix in order to adhere a toner image, which has been transferred onto the paper, paper and toner, to the roller by melting the toner and to run with it,
to be fixed permanently on paper. To these the cause for this is presumed that to

Various techniques include the melting 65 many Siioxanringe in the silicone elastomer coating by jet heat, by steam melting, by existing or at the increased temperature newly conducted heat transfer over the paper and which are formed.
Technique of Fuser Rollers With Heated Rollers It is an object of the present invention to provide a

silicone-elastomer-coated fuser roll with improved non-stick properties and longer lifespan. In particular, the Siloxane rings from the silicone elastcyier be so far removed that they have no adverse effect on the Have non-stick properties.

This object is achieved with the fusing roller according to the invention with a silicone elastomer coating solved in that the volatile components of the coating material are reduced to such a value that the coating under operating conditions, at a certain temperature and a certain pressure, a substantially constant Exhibits weight loss

A method for the production of a scamelzfixierrolie according to the invention is characterized in, that core and coating to a temperature which is at least the normal operating temperature of the Fuser roller corresponds to, heated and kept at this temperature that simultaneously with the The roller including the coating is exposed to a vacuum that is sufficient to in order to lower the boiling points of the volatile components of the silicone elastomer below the prevailing temperature, that temperature and vacuum exposure are maintained until the Time derivative of weight loss, at a constant temperature and at a constant Pressure, is essentially a constant.

It is achieved in an advantageous manner with the invention that the non-stick properties of silicone elastomer coatings are significantly improved and are stabilized. This is due to the removal of the siloxar rings and the early breaking of semi-stable bonds that would otherwise lead to the release later and formation of siloxane rings by the simultaneous application of appropriate heat treatment and vacuum exposure.

The invention is explained in more detail below using an exemplary embodiment Figure generally shows the weight loss over the exposure time at a specific temperature.

For the sake of illustration of a preferred embodiment, the description of the materials and methods is made with respect to a silicone rubber manufactured by General Elektrik Corporation is manufactured. Other silicone rubbers that behave the same or in a similar way, also appear suitable

Said special material is composed of four components and in a single one Containers already mixed together. The main component of silicone rubber is holydimeothylsiloxane with approximately

1000 Si-O units is an integer and is about 1000. Furthermore, two filler materials are included in the entire material. The first filler material is silicon dioxide (SiOj) and the second filler material is iron oxide (FCjO ₃ ). In addition to the three ingredients mentioned, there is a fourth ingredient which is a three-functional silane of the form

R-Si-CH ₃

where R represents an organic group.

As a separate material is dibutyl tin dilaurate intended as a catalyst. Dibutyltin dilaurate catalyst contains the above four ingredients filled to the vulcanization or networking of the To cause basic components. With advancing Vulcanization or cross-linking creates an elastomeric cross-linked structure.

Due to incomplete crosslinking or vulcanization, a lot of the siloxane rings

as general formula

CH ₈

Si-O

CH ₈

formed, where η is an integer and is between 3 and 8. The structure is in the form of a ring put together. The following siloxane ring, in which η equals 4, may stand as an example

CH ₈ -Si-CH ₃

per linear chain.

CH ₈

μ Si - ο

CH ₈

This chemical formula above denotes the more general form of the chain links, where η

These siloxane rings are present as disturbances in the polymer, and they will also then formed when the cross-linked structure is destroyed by thermal effects. The chains in the

As a natural phenomenon, net structures have some bonds that are weaker than others. When the material is heated, energy is released through which these weak bonds break and then a segment of the longer chain of

the crosslinked structure is separated and continues to break apart until a point in time at which η of the general formula for siloxane rings is then in the range between 3 and 8. These materials are then chemically stable at elevated temperatures

and exist in either liquid or vapor form, depending on your individual

- Melting and boiling points and the prevailing Conditions. The siloxane rings have different ones

Pressure values boiling point pressure η in ° C in now ed 133 760 3 171.5 760 4th 205 760 5 236 760 6th 147.5 20th 7th 168 20th 8th

Boiling points, which depend on their molecular weight, are linked to the chains and form additional ones. Some boiling points are so high, such as siloxane rings to those already in the polymer from the start, that it is necessary to reduce the ambient pressure on rings that are below. When these are formed. lowering the pressure or vacuum in order to volatilize these materials then go into liquid or vapor form quickly enough to build up these 5 states, depending on the number
Products to avoid. The boiling points of the siloxane rings of interest are in the following |
Blackboard illustrated. _ Si - O units

Table ^l0

Boiling points of siloxane rings with special «? ^the special siloxane and depending on de.

Temperature at which the material is located.

It was found that the removal of the siloxane rings, which occurred after the vulcanization phase before -15 are available, and those that are at elevated operating temperature, on the heated rollers necessarily work must be newly formed due to the breakdown of metastable networks good influence on the non-stick properties of the role ao and thus the life of such roles so because improved so that now silicone elastomer-coated rollers are economically and functionally flawless can be used. The processes and conditions for rapid removal and »5 for curing or crosslinking the coating

The curing or cross-linking temperature must, as can be seen from the table below, above the operating position process, explained from the beginning,
temperature of the roll, preferably it is a roll core is made according to the desired

Above the boiling point temperature of the measurements produced and placed in a rotating device that has the highest boiling point and removed 30. The silicone material is meant to be mil together. At a pressure of about 20 mm Hg, a dibutyltin dilaurate catalyst is used, dei ie 20 mm of mercuric acid, the temperature is added up to about 0.50 percent by weight is above about 168 ⁰ C. The operating temperatures This mixture is then added to the roll under Dreder roll are between 171 and 193 ° C. The hung applied, namely in a coating curing or crosslinking temperatures are 35 thick between 0.075 and 0.15 mm. The roll is about 26O ⁰ C and thus are large enough to have sufficient mm Hg to then after the coating continuously gedrehl effectiveness with applied vacuum pressure and at room temperature for about 24 hours 20 ge-dried to remove the unwanted product. To be removed from room ducts after drying for 24 hours. temperature is the temperature of the roll to about

It has been found that the increased from the beginning of 40 66 ⁰ C for a period of 4 hours in the polymer and at temperature to achieve essentially a complete vulcanization action as degradation products newly formed siloxane. After the heat treatment at 66 ° C., the silicone rubber coating apparently had a negative effect on the 4 hours and the non-stick properties of the silicone rubber coating had decreased in thickness to a thickness of approximately. The general structure of these siloxane rings is 0.0625 to 0.125 mm.

door very similar with the materials that are considered non-stick After downsizing the coating on the

medium are known, for example polydimenthyl- desired thickness is the role in a vacuum is siloxane. The primary difference is spent furnace and the temperature of the roller aui that the siloxane rings have a detrimental influence on the about 260 ⁰ C accommodated for a period of 24 stun surface properties of the silicone rubber, so the. The vacuum oven is operated at about 736 mm Hg Va. The siloxane rings have a tendency to keep the rubber kuum.

sticky, although generally a relatively In accordance with the invention properly understood

has low surface energy and therefore does not believe that the high temperature of something is sticky or attractive. It is known ^{per se the 260 0} C, which is significantly above the normal Be Use of polydimenthylsiloxanes as the anti-operating temperature of the heating roller, in Dampffora adhesives, but these are in connection with the siloxane rings, which are known as reaction residues other than silicone rubber. When crosslinking processes occur, as well as such, are known polydimenthylsiloxanes either in the siloxane rings, which from the beginning in the polymerisation were used directly as a coating on steel rollers or were present. In addition, the Tem on rolls coated with polytetrafluoroethylene. 60 temperature at which the roller is held, each weak. In use, it becomes evident that, although bond in the crosslinked structure of the silicone elasto, these siloxane rings in some contexts broken so that additional siloxane rings have a good effect in the present case Use to be formed. The bonds that are broken open when coated with dry silicone elastomers are those that are the least stable and unstable on a heated roller, they have a very detrimental effect and are most likely to cause the effect at normal heating temperatures. heated roll during breaker operation

When the temperature in the roll and would. The vacuum that occurs during the on-coating rises, then break the weak heating of the roller is present, supports the heat

Effect on volatilization of the siloxane rings and on targets or by curing up to one

their removal from the rubber roller. It is necessary to point high enough on the curve, either in the

dig that siloxane rings quickly through the heat and area 10 or 12 that is below the reduced

Remove vacuum treatment, especially to operating temperatures and atmospheric pressure

• To remove such siloxane rings which, from the higher 5, essentially reduce the rate of weight loss during operation.

Are molecular weight. These are meant to be effective instantly borrowed is constant

then removed as they arise. If this is in the state and under the conditions specified by If it is not the case and rings are formed, the area 14 shown disappearing will be acceptable this only very slowly, §o that it reaches at least one and reliable non-stick properties of the melt-growing transition state of siloxane rings 10 fixing role. During the curing process, the form which are detrimental to the sustained reliable rate of weight loss in areas 10 and 12 Working method of the material are. by increasing the applied temperature

In the successive execution of the steps mentioned and / or by increasing the applied Vabein in the above example has been accelerated cumulative. Accordingly, will found that the simultaneous heat and vacuum lowering and / or the temperature treatment of the coated roll as long as the rate of weight loss in these temperatures is sufficient to achieve a satisfactory roll 10 and 12. Reach Ku until the level of the siloxane rings reaches a level. The curve shown in the figure is more general Point is reduced at the siloxane rings of the same type, but can be removed with suitable scales for to-be-rate as they arise again. Extra working roles as well as those in operation

This condition can best be applied on the basis of scrolling. Weight loss of the role, if for a satisfactory removal of the siloxane

this is treated or manufactured and operated. rings to ensure reliable working

A characteristic property of elastomeric conditions to create as well as a long life Silicone rubber material that is guaranteed by vulcanization is the application of a temperature

forms is that, as long as the material temperature, which is at least the same, but in general

When exposed to heat, degradation of the polymer is greater than the normal operating temperature

occurs and siloxane rings are formed. Fusing process, and the simultaneous application

It is therefore essential to use vacuum in the present technology. The simultaneous loading

impossible to remove all siloxane rings and the action is with vacuum and elevated temperature

Avoid the formation of further siloxane rings, if necessary, because vacuum alone is only such

the elastomeric structure would remove siloxane rings that are in liquid or elevated operating temperatures

is exposed. The F i g. 1 represents a general graph of the vapor state under normal space

of weight loss as a function of time at which temperatures are present. These are siloxane rings

Heating to a certain temperature. Of the 35 low molecular weight ones. Unaffected Area of the curve in FIG. 1, which would be designated with 10 such siloxane rings in this procedure

is, can be referred to as a transition state, the material remain, the higher molecular weight

occurs during the time when the residual products have the.

Vulcanization or cross-linking, especially the A similar application of heat alone, Siloxane rings, which are removed and at what time 40, especially at extremely high temperatures, harbors the

due to the prevailing temperature of the curing- danger inherent in converting the rubber into simply formed siloxane

process to convert additional siloxane rings due to the ring that occurs at atmospheric pressure

breaking the metastable bonds of the crosslinked can hardly be volatilized from the material.

Materials are formed. The rate of evaporation of these siloxane rings, labeled 12, is relative The area of the curve is the area where a stability is low compared to others, easily volatilized.

lization occurs and the removal rate reduces lowing materials, so that a large quantity of

is due to the fact that excess siloxane rings can be formed in rubber without

Vulcanization residues no longer ensure adequate removal when cured with

distance are available and that the only higher temperature without simultaneous vacuum

Material available for removal 50 application.

such is that on an ongoing basis based on the foregoing statement and the foregoing

the increased operating temperature is formed. Example concerned a silicone rubber material from

The area of the curve labeled 14 indicates General Elektrik Corporation. It should be noted, however

the static state that may be the result of removing other, similar materials from others

of the vulcanization products and the initial 55 companies are available and that these are from the same

existing siloxane rings are due to the initial general nature, d. that is, they have a long chain of

Temperature increase has been reached. Have the production of silicone elastomers. The main difference

Consists of siloxane rings by breaking down the basic between the different silicone rubbers

elastomeric layer is thus at a constant rate essentially in that different amounts and

has been stabilized, and mathematically this 60 different types of filling material can be used

Area that is shown in FIG. 1 is denoted by 14, as d will. These filling materials are used in place of the

(Weight loss) / dt = k . The ab- in the present example used Fe ₁ O ₃ and des

Conducting weight loss over time results in a SiO, material used These materials have

Constant according to which the disruptive siloxane rings generally have little or no influence

have been removed. 65 on the polymerization and are in fact only physically

The constant rate of weight loss can be kaiische filling materials. They do influence, however

under operating conditions either by achieving the thermal properties and other physical

a constant rate or closer observation of erratic properties as well as the rate of formation of

Siloxane rings. The exact conditions for curing for each particular material and the optimal ones Curing conditions for a particular material depend on: the for the curing time available, depending on the operating temperature of the fusing roller normal operation and from the particular silicone elastomer material used. The important one The point in the making is that the rate of weight loss for the silicone material is reduced to one must be stabilized in an approximately constant value before a state of equilibrium is reached. In this State of equilibrium are the properties such that the most favorable conditions for reliable Repulsion of thermoplastic to be melted

Material and its backing material from the fuser roll are present.

In some cases it may be possible to reduce the non-stick properties already secure in the part of the curve that is labeled 12 or as the knee in the curve is. This is possible when the level of the siloxane rings in the material is already on a relative basis low value has been lowered. In practice, it is not possible to use percentages to determine the level

ίο the siloxane rings with normal laboratory equipment and test techniques. This is why dei weight loss has proven to be a definite measure of what you want Structure of the material and those influencing the material in the present application

is highlighted effects.

1 sheet of drawings

Claims (2)

or with roles that work under particularly high pressure. Within the fuser roll techmk there are 1. Fuser roller with a coating of two different solutions. One consists of the a silicone elastomer for an electrophotographic use of a rigid, non-deformable heating element Device for fusing the thermal roller and an elastic pressure roller, and the plastic material on a carrier, thereby using a rigid pressure roller and other technique characterized in that the volatile grain is an elastic heating roller. In both cases the components of the coating material on an elastic roll generally as a stable, solid cylinder are reduced to such a value that the coating ίο carried out on which a layer of an elastounter Operating conditions, of certain tempera- tures, material is attached to the pressure gap temperature and certain pressure, one essentially between the opposite pressure roller exhibits constant weight loss. malleable isL in this way becomes a larger 2. Roller according to claim 1, characterized marked imprint area created by the two roles that the volatile components siloxane 15 surfaces are in very close contact with each other, rings with the basic structure. This imprint area in the gap is necessary to to have enough time to heat the toner to it CH,