FR2608504A1 - SILICONE FOAM SHEET CONTAINING A CONTINUOUS MAT OF INCOMBUSTIBLE AND INFUSIBLE FIBERS - Google Patents

Abstract

A SHEET OF SILICONE FOAM, IN WHICH A CONTINUOUS MAT OF INCOMBUSTIBLE AND INFUSIBLE FIBERS IS INCORPORATED, PROVIDES RESISTANCE TO FIRE AND FLAME, EVEN ALONG LINES OR POINTS OF CONSTRAINT.

Description

The present invention relates to a foam sheet of

  silicone containing a continuous mat of non-combustible and infused fibers

  sibles. More particularly, the invention relates to silicone foams for stopping flames containing non-combustible and infusible reinforcing fibers. Many applications requiring fireproofing require protective and insulating silicone foams. To date, silicone foams have been used effectively for fireproofing electrical installations, buildings,

  planes, automobiles and furniture.

  Silicone foam resists contact for a while

  direct from a flame without penetration of the flame. Soft Foam Cis

  tooth to carbonize and form protective ash at the point of contact with flame or heat. The protective ashes prevent the propagation of the flame in the body of the foam and,

  when the thickness of the ashes increases, they prevent the

  following the decomposition into ashes of the silicone foam.

  A silicone foam can be used in the form of a film or sheet and, due to the elastomeric nature of the foam, it can be folded or deformed so that it adapts to various shapes. However, when the silicone foam sheet has a pronounced curvature or angle, a stress is established which leads to the formation of cracks in the foam during oxidation and pyrolysis. Therefore, when a flame is applied to a curvature or to a corner of the silicone foam sheet, the surface oxidizes into fragile silica, a crack forms in the sheet, due to the curvature stress, and the

  flames penetrate the leaf.

  The object of the invention is to produce a sheet of silicone foam having improved resistance to flame penetration at an angle of curvature or at another point of stress and to produce such a sheet having a reduced tendency to crack.

under stress in the oxidized state.

  The invention will now be described in detail.

  The invention provides a sheet of silicone foam containing

  nant: (a) a layer of silicone foam and (b) incorporated therein, a continuous mat of fibers

noncombustible and infusible.

  The silicone foams used here are currently produced by two main processes. Each process uses the in situ formation of hydrogen gas and the simultaneous crosslinking of a silicone elastomer. Less preferred methods of expanding silicone elastomer include the use of a blowing agent. A composition for silicone foam suitable for use in the invention comprises (a) 100 parts by weight of a basic vinyl polymer of formula:

I. R1 R

8

R - SIO --S) - S.R

  RR1 xRl el in which R and R1 are chosen from alkyl radicals of 1 to 8 carbon atoms, aryl radicals, vinyl radicals and fluoroalkyl radicals of 3 to 8 carbon atoms, such that the polymer contains from 0.0002 at 3% by weight of vinyl and x varies

  so that the viscosity of the polymer is from 100 to 1,000,000 centipoi-

  its at 25'C; (b) from 0 to 200 parts by weight of a filler; (c) from 100 parts per million to 1.5 parts by weight of water; (d) from 1 to 50 parts by weight of a polymer hydride of formula: R3 Z y R3 R2 | î 5 40fio 40 S 5 R2 (2) in which R2 is chosen from hydrogen, alkyl radicals of 1 to 8 carbon atoms and aryl radicals and R3 is chosen

  among the alkyl and aryl radicals having up to 8 carbon atoms

  bone, the hydride polymer having a hydrogen content varying from 0.3 to 1.6% by weight, o z and y vary so that the polymer has a viscosity of 5 to 100 centipoise at 25 ° C; and where there is at least

  0.2 mole of SiH per mole of water; and (e) from 1 to 250 parts per half

  lion of a platinum catalyst. It is preferred that the vinyl polymer

  that basic only contains terminal vinyl patterns, however it may contain vinyls on the chain 2 motifs. As far as polymer hydride is concerned, this polymer must have an atom

  of hydrogen on the polymer chain to produce a suitable foam

  prayed. However, in addition to the hydrogen atoms in the chain,

  terminal hydrogen atoms may be present. A poly- hydride

  mother having only terminal hydrogen atoms cannot be used as crosslinking agent. As indicated above, it is necessary that the composition has at least 0.2 mole of hydrogen in the crosslinking agent, consisting of a polysiloxane containing a hydride, for each mole of water, in order to release sufficiently

  of hydrogen to produce a suitable foam.

  The above composition is used to produce a foam by simple mixing of the ingredients which are allowed to react in two main reactions. A reaction produces hydrogen gas by reaction between water and the polymer hydride and causes

  expanding composition. The second reaction hardens the composition.

  sition into a silicone elastomer by reaction between the vinyl functional groups and the polymer hydride. Of course, if we

  applies heat, the reaction takes place very quickly.

  This silicone foam composition is further described in

U.S. Patent No. 4,189,545.

  Another composition for silicone foam suitable for use in the invention comprises (a) an organohydrogensiloxane having on average at least three hydrogen atoms bonded to silicon per molecule, on average not more than one hydrogen atom bonded silicon by silicon core and organic radicals chosen from the group consisting of alkyl radicals having 1 to 6 carbon atoms per radical, phenyl and 3,3,3trifluoropropyl; (b) a hydroxylated organosiloxane having on average more than 1.0 to 2.5 hydroxyl radicals bonded to silicon per molecule and having on average per silicon atom at least one organic radical chosen from the

  group consisting of alkyl radicals having 1 to 6 carbon atoms

  bone by radical, phenyl and 3,3,3-trifluoropropyl; and (c) a platinum catalyst in an amount of 5 to about 200 parts by

  weight of platinum per million parts by weight of the composition

  total tion. The organohydrogensiloxane and the hydroxylated organosiloxane must be present in sufficient quantities to establish a molar ratio of the hydrogen atoms bound to silicon to the radicals

  hydroxyls bound to silicon from 2.5 to 40.

  It is easy to transform the silicone composition into a foam by simply mixing the ingredients which are left to react. The main reaction produces hydrogen gas to expand the composition and simultaneously cross-links the polymers to harden the

composition.

  The main reaction mechanism consists of a reaction

  tion of the hydrogen atom of a hydroxyl group on the organosili-

  hydroxylated cone with a hydrogen atom on the organohydrogensilo-

  xane to produce a hydrogen molecule and a Si-O-Si bond.

  This silicone foam composition is further described in

U.S. Patent No. 4,189,545.

  The ingredients of either of the silicone foam compositions suggested above can be mixed according to standard practice. For example, it is possible to mix the polymer hydride or the organohydrogensiloxane with the platinum catalyst, then mix with the vinyl base polymer and water or with the hydroxylated organosiloxane. Alternatively, the platinum catalyst can first be mixed with the vinyl base polymer and water or

  with the hydroxylated organosiloxane, then mixed with the poly- hydride

  mother or organohydrogensiloxane, as appropriate. Other processes

  are also suitable, for example the polymer viny-

  lique and water or hyi xylated organosiloxane can be divided into

  two portions, one portion being mixed with the catalyst

  tine and the second portion being mixed with the polymer hydride or organohydrogensiloxane, the two mixtures then being combined to form a foam. Various optional ingredients, such as a silica filler, can be mixed with one or more of the required ingredients as appropriate. These "sets" of ingredients

  may consist of any combination of the ingredients

  dients, as long as a premature reaction does not occur before all the ingredients are present in the mixture. For storage, polymer hydride or organohydrogensiloxane must not

  not be stored as a "whole" or mixed with the cat-

  platinum lyser, as gas evolution may occur.

  To control the expansion and hardening reactions that occur simultaneously, an inhibitor of

  platinum catalyst, such as cyclic polynethylvinylsiloxanes

  ques and acetylenic alcohols. Catalyst inhibitors

  platinum are known in the art and there are many different

  your. However, these inhibitors should not hinder expansion and

  hardening to the point of destroying the foam constituting the pro-

  of the invention. The mixture of ingredients must be placed in the place where it is desired to use it from the moment of mixing, because the expansion

  starts immediately, unless a catalytic blocker is used

  platinum to increase pot life so that the mixture

  can be made and then placed where you want to use it.

  Inhibitors are present in relatively small amounts

  and up to 2 parts by weight of polymethylvinyl-

  cyclic siloxanes to control the initiation of expansion and hardening. Cyclic polymethylvinylsiloxanes are known in the art and can be prepared by hydrolysis for example

methylvinyldichlorosilane.

  The density of the above foams can be reduced when necessary or desirable by incorporating MDQ polyorganosiloxane resins. These resins include R4SiO05 (M), R4SiO (D) and SiO2 (Q) units in which R4 is chosen from ronova] ents substituted and unsubstituted hydrocarbon radicals. These resins and their use for the above purposes are further described in

U.S. Patent No. 4,418,157.

  The non-combustible and infusible fiber mats for use in the invention may contain mineral fibers, for example glass fibers, asbestos fibers, graphite fibers, etc. or even organic fibers with very high heat resistance, such as polyimide fibers. It is essential in the invention that the fiber mat does not burn or melt when exposed to the temperatures of ordinary flames, i.e. at temperatures of at least about 300 ° C or more, and of preference to

  temperatures of at least about 500 ° C or more.

  The term "mat" as used herein refers to a layer of nonwoven, woven, needled or interwoven fibers

  way that distributes an applied load over a large area.

  The mat can for example be made of continuous fibers or

  bundles of parallel continuous fibers intermittently joined

  tent with perpendicular transverse fibers. Otherwise, the mat can be made of short fibers woven into a mat. The mat can be bulky, that is to say with loose weave, which allows

  fibers come out of the plane of the mat, or the mat may not be volumi-

  neux, that is to say being of tight texture, the fibers being narrow-

  retained at the level of the mast. The infused mineral fiber mats

  wheat which is preferred to be used here generally has a fiber content of from about 1 x 10-3 to about 5 x 10-1 g / cm2 and preferably

  from about 5 x 10-3 to about 1 x 10-1 g / cm2.

  To produce the composite article of the invention, one applies

  that the silicone foam composition has at least one face of the

  infusible mineral mat and we expand it.

  For best results, the silicone foam composition should be prepared to have a viscosity of one

  million centipoises at 25'C and should preferably have a viscosity

  sity between around 500 and 100,000 centipoises at 25'C. The purpose of adjusting the viscosity is to obtain controlled penetration into the mat, with good cell formation in the foam. The penetration of the nat ut be complete, which produces a

  foam on both sides and a completely incorporated mat. However

  while it may also be desirable to maintain one side of the mat

  as the external face of the composite, i.e. only incorporate

  matly. In this case, only one penetration is allowed.

  tielle, that is to say a penetration sufficient to ensure the adhesion

  one side of the mast. In addition, the composition and the expansion conditions must be such that a foam is produced having a density of ernsron 0.08 to 0.4 g / cm3 and preferably

from about 0.16 to 0.32 g / cm3.

  The composition for silicone foam is matted according to known methods, for example with a roller, doctor blades, etc. Generally, enough silicone foam composition should be applied so that the thickness of the foam on one side of the mat is at least about 1.5 mm. Thinner thicknesses do not

  provide almost no resistance to flame penetration.

  The thickness increases according to the desired degree of protection against fire. Generally, the thicknesses of the foam for many

  applications are between about 6 mm and about 5i mm.

  The silicone foam composition is preferably mixed from sets just before mat application, but it is understood that mixing can be carried out on the surface of the

  matt, for example when using low-strength silicone polymers

ble viscosity.

  A preferred method of applying the silicone foam composition to the mat comprises passing two sheets of an impermeable film, such as a polyolefin film, in the interval of two rolls and in the interval formed thereafter o the polyolefin sheets are in mutual or adjacent contact, the

  passing a layer of mat with the silicone foam composition

  cone on one or both sides. Of course, the foam

  silicone obtained has a polyolefin lining which can be removed

  worm. The use of impermeable film limits the escape of hydrogen gas and also prevents the composition for

  silicone foam adheres to the roller.

  The expansion of the composition can be accelerated by the application of heat. Too vigorous expansion alters cell formation and produces irregular foam. However, it can be heated to increase the production rates and to limit the penetration of the silicone foam composition.

  in the mast. Heat can be applied by convection or ray-

  ment. The temperature in the foam mass should not exceed about 65'C, however, the oven temperature or the

  the surface of the foam can be much higher.

  The silicone foam composition can be added

  fillers usually added to prepare such foams

  his. These fillers include fumed silica, diatomaceous earth

  meas, zinc oxide, calcium carbonate, ground quartz and

  similar. The maximum amount of charge to add depends on the pro-

  desired properties of the foam. Generally, one can use

  up to about 60% by weight of filler.

  To increase the combustion resistance of the above silicone foams, other combustion resistance additives can be used. For example, for 100 parts of the resin portion of the silicone foam composition, one can add

  0.1 to 10 and preferably 0.5 to 2 parts by weight of carbon black

  bone to increase the combustion resistance of the foam.

  When using carbon black, the foams are faster-

self-extinguishing.

  The following examples are presented for illustrative purposes only-

  and should not be construed as limiting this

  invention which is defined by the claims.

Examples

Example 1

  Composition A contains 100 parts by weight of polydlré-

  vinyl-terminated fluid thylsiloxane, 25 parts by weight of an MDVinYl Q resin, 1 part by weight of water, 20 ppm of catalyst with

  platinum capable of gelling the foam in 20 minutes and 50 parts e :.

  load weight if crushed. Composition B contains 20 per

  parts by weight of vinyl-terminated fluid polydlmethylsiloxane d-

  000 centipoises and 80 parts by weight of methylhydrogenosiloxanr fluid with trimethyl termination of 30 centipoises. We combine I0

  parts by weight of composition A to 1 part by weight of the cor.-

  position B to obtain a composition for saicone foam d-

  000 to 40 00C centi-poises. The composition for foam dz s: lconr

  immediately begins to react and harden.

Example 2

  The composition for silicone foam of the exe is mixed: -

  pie 1 and we introduce it continuously in the interval created by eu

  rolls between which pass two continuous sheets of polythy-

  lene. The foam sheet obtained hardens to a thickness of, E r ::

  in about 5 minutes and the poly4thylene coating is removed.

Example 3

  We vertically align a section of the red leaf

  of silicone from example i so that the two sides are visible

  your. Apply a gas flame having a temperature of approximately 1150 ° C at the center of one face of the vertical section and a layer

  silicon oxide immediately forms on the surface. When:

  continues the application of the flame, the surface struck by the flame cracks and begins to remove itself under the effect of the simple impact force of the flame. The flame freely enters the

silicone foam sheet.

Example 4

  A section of the silicone foam sheet of Example 2 is subjected to a stress by folding it at a not very tight angle of 90 '. A gas flame is applied to the outer surface of the curvature and a layer of silicon oxide is immediately formed on the surface. When the application of the flame is continued, the area struck by the flame cracks and begins to remove under the simple impact force of the flame. The flame penetrates freely

  in the silicone foam sheet.

Example 5

  Example 2 is repeated except that, in addition, a mat (glass fiber manufactured by Clark Schweble Fiberglass Company, of White Plains, NY (style 1609, size CS210) having 4 is introduced into the interval between the rollers. , 7 x 1.6 fiber bundles / cm2 and weighing 5.1 x 10-3 g / cr, 2. The foam composition is introduced in the meantime on one side of the glass mat, so that

  the mat is partially visible on one side.

Example E

  The experiment of Example 3 is repeated by applying a gas flame to the sheet of silicone foam of Example 5 on the face of foam. When the exposure continues, the area struck by the flame cracks, but does not come off. The flame does not penetrate the silicone foam sheet, even after prolonged exposure.

Example 7

  The experiment of Example 4 is repeated by applying a gas flame to the sheet of silicone foam of Example 5 on the face of foam. When the exposure continues, the area struck by the flame cracks, but does not come off. The flame does not penetrate the silicone foam sheet, even after prolonged exposure.

Claims (15)

  1. Silicone foam sheet characterized in that it comprises: (a) a layer of silicone foam and (b) incorporated therein, a continuous mat of fibers noncombustible and infusible.   2. Fe of silicone foam according to claim 1, characterized in that said fibers do not burn or melt when exposed to temperatures of at least about 300'C or more.   3. Silicone foam sheet according to claim 1, characterized in that said fibers do not burn or melt when exposed to temperatures of at least about 400'C or more.   4. silicone foam sheet according to claim 2,   characterized in that said fibers are mineral fibers.   5. Silicone foam sheet according to claim 2, characterized in that said fibers are organic fibers heat resistant.   6. silicone foam sheet according to claim 1, characterized in that said continuous mat is partially incorporated. 7. silicone foam sheet according to claim 1,   characterized in that said continuous mat is completely incorporated.   8. A silicone foam sheet according to claim 1,   characterized in that said continuous mat has a fiber content   taken between about 1 x 10-3 and about 5 x 10-1 g / cm2.   9. silicone foam sheet according to claim 1,   characterized in that said continuous mat has a fiber content   taken between about 5 x 10-3 and about 1 x 10-1 g / cm2.   10. A silicone foam sheet according to claim 1,   characterized in that said fibers are continuous fibers.   11. Silicone foam sheet according to claim 1,   characterized in that said fibers are short, woven fibers in continuous beams.   12. silicone foam sheet according to claim 1, characterized in that said silicone foam has a thickness at least about 1.5 mm.   13. silicone foam sheet according to claim 1, characterized in that said silicone foam has a thickness from approximately 6 mm to approximately 51 mm.   14. Silicone foam sheet according to claim 1,   characterized in that said silicone foam has a density   only from about 0.08 to about 0.4 g / cm3.   15. Silicone foam sheet according to claim 1,   characterized in that it contains a hard catalyst residue platinum curing.