Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Primarily organic continuous liquid phase
Reexamination Certificate
2001-05-14
2004-09-07
Cooney, Jr., John M. (Department: 1711)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Primarily organic continuous liquid phase
C252S001000, C252S182240, C252S182270, C516S033000, C516S034000, C516S199000, C521S107000, C521S114000, C521S116000, C521S117000, C521S155000, C521S170000, C521S174000
Reexamination Certificate
active
06787575
ABSTRACT:
The present invention relates to the technological sector which manufactures polyurethane foams and more specifically to the mineral fillers used in this sector, in particular fillers of the carbonate, hydroxide, silicate and sulphate type and similar mineral fillers.
It is known that polyurethane foam (or PUR) is obtained by the reaction of a polyol on an isocyanate such as toluene diisocyanate or TDI, concurrently with a reaction of the isocyanate on water.
To produce block foam, the “mixing head” is charged either with a master batch of polyol and mineral additive on the one hand and on the other hand the remaining polyol, the catalyst system such as an amine catalyst, tin catalyst or any other catalyst, one or more surface active agents, generally of the silicon type, water, toluene diisocyanate, optionally an auxiliary foaming agent which may be methylene chloride, acetone and various additives such as heat stabilising agents or, alternatively, with the polyol in which the master batch has been diluted to the desired concentration beforehand and on the other the above-mentioned additives (catalyst, surface active agent, etc . . . ).
The reaction of the water on the isocyanate, catalysed by the amine, generates CO
2
which forms the foam.
In order to reduce the cost price per litre and per kilogram of objects made from flexible, semi-rigid or rigid polyurethane foam, which may or may not be moulded, it has become increasingly necessary to increase the quantity of filler contained in the flexible, semi-rigid or rigid polyurethane foams whilst conserving or improving their physical-chemical properties, such as compression modulus or tear strength, or improve their aesthetic or other qualities such as their fireproof qualities, a required by the different fields of industry such as the automotive, furniture, building and other industries.
These days, there are several methods of incorporating the mineral fillers with these polyurethane compounds.
In a first type of method (FR 2 651 236), calcium carbonate is introduced into a polyurethane plasticiser. This method of producing a suspension of filler in a plasticiser, which allows the proportion of filler in the polyurethane compound to be increased, has proved to be expensive and too awkward to implement when manufacturing flexible, semi-rigid or rigid polyurethane foams because of the accompanying deterioration in the physical and chemical properties of the foams obtained using this filler suspension.
Attempts were then made to introduce the mineral fillers to the flexible, semi-rigid or rigid polyurethane foams in a simpler, less costly manner, eliminating the inherent problem which causes a significant reduction in the reaction capacity of the polyurethane foams.
To this end, various methods of introducing the filler into a polyol, one of the ingredients of polyurethane, have become known to those skilled in the art.
A first type of method is based on a teaching of grafting methacrylic acid (DE 2 654 746, DE 2 714 291, DE 2 739 620) or another vinyl compound such as styrene onto the polyol. However, with this type of method the calcium carbonate suspension in the polyol becomes unworkable, being too difficult to handle due to a very high viscosity and a poor distribution of the filler in the medium in conjunction with problems caused by sedimentation of the suspension.
Another type of method consists in treating the surface of the filler before it is introduced into the polyol using an agent, which might be an alcohol with 8 to 14 carbon atoms for example (FR 2 531 971) or a phosphate of hydroxycarboxylic acid (EP 0 202 394).
However, these methods produce the same type of disadvantages as those outlined above because the user is faced with problems caused by the poor capacity of the mineral filler treated in this way to disperse in the polyol.
Another method of treating a mineral filler has been developed (EP 0 726 298) using at least one agent of the organic phosphate type for treatment purposes, in conjunction with a treated mineral filler, producing a suspension of mineral filler in the polyols which has a high filler content and a low viscosity, i.e. a homogeneous suspension which is not susceptible to sedimentation or to decantation, nor does it inherently thicken when manufacturing flexible, semi-rigid or rigid polyurethane foam.
According to this document, the mineral fillers are treated with a view to placing them in suspension in the polyols with the aid of at least one agent of the organic phosphate type for treatment purposes, having the general formula (1):
where R
1
=either H or alkyl with 8 to 40 carbon atoms or aryl or alkylaryl or arylalkyl with 6 to 40 carbon atoms
where R
2
=either alkyl with 8 to 40 carbon atoms or aryl or alkylaryl or arylalkyl with 6 to 40 carbon atoms
X=—CH
2
—CH
2
—
Y=CH(CH
3
)—CH
2
— or —CH
2
—CH(CH
3
)—
(m+n) varies from 0 to 30 where m≦30 and n≦30
(p+q) varies from 0 to 30 where p≦30 and q≦30.
This latter technique is satisfactory but a new problem has been encountered in connection with a specific and more recent technique of manufacture of PUR foams.
According to the conventional method, the mixer head is charged with a mixture of polyol and mineral filler on the one hand and the remaining polyol, TDI, an auxiliary foaming agent such as methylene chloride and various additives such as a tin salt and a surfactant, generally of the silicon type, on the other. The reaction generates CO
2
in situ, as mentioned above, which forms the foam. Formation of the foam passes through two main stages, the first occurring at the onset of foaming and the second when the foam block is being stabilised, after which a mass of PUR foam is produced which is then cut into blocks of the desired dimension in order to make mattresses, seat coverings, etc . . .
A new method has been developed in recent years and is described in particular in patents EP 0 645 226 and WO 96/00644, whereby the CO
2
is injected into the mixing head directly or through the polyol flow in the liquid state. The CO
2
is therefore used as an auxiliary blowing agent.
This method has advantages, particularly in terms of reducing in quite a remarkable way the use and formation of toxic or inflammable products and is likely to take on increasing importance in the future.
However, this new method does have technical problems in addition to those inherent in manufacturing PUR foam.
In order to implement a method of this type correctly, known as PUR foam with CO
2
or “CO
2
method”, it seems to be necessary to reduce significantly the time needed to mix the filler with the polyol and to improve the mixing quality.
As proposed by this invention, it has been found that the problem of the mixing time and the difficulties inherent in the new CO
2
method can be resolved by treating a mineral filler in a manner comparable to the techniques described in EP 0 726 298, but with significant improvements.
Surprisingly, it was also discovered whilst conducting research into the CO
2
method that the method used to treat the mineral fillers as proposed by the invention also improves the conventional processes used to manufacture PUR foams.
Accordingly, the invention is not limited to the CO
2
processes, which was the original problem to be resolved, but on the contrary is applicable in a general manner.
It has also been found that the method proposed by the invention for treating mineral fillers can be applied to the methods used to manufacture composite materials with a PUR matrix, whether or not they are cellular, and that whatever the filler used: CaCO
3
, talcs, kaolins, aluminium hydroxide, magnesium hydroxide, etc . . . in numerous applications in the field of accessories for the automotive industry, for the transport sector, in particular road or rail and for industrial objects used in a variety of applications.
By the terms “composite materials” or “composite PUR” used here is meant polyurethanes reinforced with vegetable fibres, glass or quartz or synthetic fibres, cut fibres in gene
Blanchard Pierre
Fichou Jean Pierre
Husson Maurice
Ravet Georges
Cooney Jr. John M.
Omya SA
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