FR2956117A1 - Preparing polyurethane foam, useful in seat element, comprises reacting reaction mixture comprising isocyanate composition including e.g. polyisocyanate, mixture of alkoxylated polyols, water and catalyst - Google Patents

Abstract

Preparing a flexible high resilience polyurethane foam (I) comprises reacting a reaction mixture comprising isocyanate composition including at least one polyisocyanate, a mixture of alkoxylated polyols, a crosslinking additive, water and at least one catalyst, where the mixture of alkoxylated polyols comprises e.g. 60-90 wt.% of at least one polyoxyethylene-polyoxypropylene polyol having content of primary hydroxyl functions of >= 50% with a real nominal functionality of 2.5-6, preferably at least equal to 3. Preparing a flexible high resilience polyurethane foam (I) comprises reacting a reaction mixture comprising isocyanate composition including at least one polyisocyanate, a mixture of alkoxylated polyols, a crosslinking additive, water and at least one catalyst, where the mixture of alkoxylated polyols comprises: 60-90 wt.% of at least one polyoxyethylene-polyoxypropylene polyol having content of primary hydroxyl functions of >= 50% with a real nominal functionality of 2.5-6, preferably at least equal to 3; and two alkoxylated vegetable oils of which the first alkoxylated oil is, with respect to the second alkoxylated oil, in greater weight proportion and has a hydroxyl index of not greater than 100, and the second alkoxylated oil has hydroxyl index of at least equal to 150 and the cumulative proportion of first and second alkoxylated oils are preferably 10-28 wt.%. An independent claim is included for the flexible high resilience polyurethane foam obtained by the process.

Description

The present invention relates to the field of the manufacture of flexible polyurethane foams of high resilience (HR). The present invention relates more particularly to a method of manufacturing an HR flexible polyurethane foam including bio-polyols and used for the design of cushions, backrests and accessories, in particular for motor vehicle seats. To manufacture polyurethane foam padding, a technique known as "integrated molding" or "in situ process" is known in which a mold having a cavity shaped to the shape of the padding to be obtained is used, in which the prepared cap, use face against the inner surface of the mold. The cap can be held in place in the mold by various means, including suction through the surface of the mold. Just before closing the mold, polyurethane foam is poured into the cavity, where it expands in a manner known per se, and adheres on the back of the cap in the shape of the cavity.

This technique is particularly advantageous in terms of efficiency and cost. For use of polyurethane foam padding as seat and / or seat backs, it is desirable that the polyurethane foam has a high resilience.

The invention applies to processes using both the "in situ" technique and other more conventional molding techniques. It is known from EP1842866 and WO 2004/020497, a flexible polyurethane foam produced by reaction of polyisocyanates, typically MDI (methylene diphenyl isocyanates) or TDI (toluene diisocyanates), with a mixture of polyols of plant origin, in particular based on polyols of a vegetable oil, which have been alkoxylated.

The advantage of the preparation of this type of foam is that the use of petrochemical polyols which has a negative impact on the environment is minimized. So that the properties of the foam are not impaired by the use of bio-polyols, it is provided according to EP1842866 to use the catalyst complex DMC (Double Metal Cyanide). Thus side reactions, especially transesterification, are minimized during the conversion of vegetable oil polyols to alkoxylated compounds. The following vegetable oils may be mentioned as non-limiting examples: castor oil, polyhydroxy fatty acid, ricinoleic acid, oils modified with hydroxyl groups, such as grape seed oil, l. Nigella oil, pumpkin seed oil, borage oil, soybean oil, wheat germ oil, rapeseed oil, sunflower oil, olive oil peanut oil, apricot kernel oil, pistachio oil, almond oil, olive oil, Macadamia nut oil, avocado oil, sea buckthorn, sesame oil, hemp oil, hazelnut oil, evening primrose oil, rose hip oil, hemp oil, thistle oil, oil of walnuts, as well as fatty acids and esters of hydroxy-modified fatty acids based on myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, petroselinic acid, gadolinic acid , of erucic acid, of nervonic acid, of linoleic acid, linocaine a and Y acid, stearidonic acid, arachidonic acid, timnodonic acid, clupanodonic acid, cervonic acid. A disadvantage of foams thus obtained is the limitation of certain physical properties, so that the flexible polyurethane foams HR obtained from bio-polyols do not meet the most demanding specifications, in particular in the field of motor vehicle seats. By way of example, while the tear resistance must be obtained at least up to a threshold load of 150N in the specifications of certain vehicle manufacturers, the tear is obtained below this threshold with current foams based on organic polyols. It has also been found that polyurethane foams based on bio-polyols have an initial resistance ("green strength") altered, which can cause mold release problems. Another drawback is the loss of lift encountered with molded foams obtained from bio-polyols, the most demanding specifications for this parameter are not met. In addition, there is a need to provide foams using bio-polyols and offering better resistance to climate and dynamic aging.

The present invention aims to overcome one or more of the disadvantages mentioned above. The present inventors, after extensive research, have found that HR foams, having good tear strength and sufficient lift, can be obtained by a process for preparing a high resilience flexible polyurethane foam in which a reaction is carried out. a reaction mixture comprising an isocyanate composition including at least one polyisocyanate, a mixture of alkoxylated polyols, a crosslinking additive (for obtaining a high-resilience foam), water and at least one catalyst, the mixture of alkoxylated polyols comprising: - 60 to 90% by weight relative to the total weight of the mixture of alkoxylated polyols of at least one polyoxyethylene-polyoxypropylene polyol having a primary hydroxyl functional group ratio greater than or equal to 50% with a real nominal functionality included in the range of 2.5 to 6, and preferably at least 3; and a first and a second alkoxylated vegetable oils, the first alkoxylated oil is, in relation to the second alkoxylated oil, in greater proportion by weight and has a hydroxyl number of not more than 100, the second alkoxylated oil having a at least 150 hydroxyl, the cumulative proportion of the first and second alkoxylated oils being preferably in the range of 10 to 28% by weight relative to the total weight of the mixture of alkoxylated polyols. Thanks to these provisions, it is advantageous to integrate bio-polyols (i.e. components derived from renewable natural resources unlike petrochemical components) in a polyurethane foam HR, without destabilizing the cellular network of the foam. On the contrary and surprisingly, the parameters of the high-resilience polyurethane foam thus obtained are particularly satisfactory, in particular the lift and tear resistance.

It is assumed that the use of two alkoxylated vegetable oils (typically corresponding to polyether alcohols prepared by fixation of alkylene oxides on the "organic" components derived from the plants), used in minority proportions, makes it possible to limit alteration of the foam, while the use of an alkoxylated vegetable oil with a higher hydroxyl number (greater than or equal to 150) allows the creation of bonds having the effect of stabilizing the cellular network of the polyurethane foam (properties of crosslinking agent). Preferably, the vegetable oils are propoxylated and / or ethoxylated oils. The percentage by weight of biomass (of non-petrochemical origin) can be increased thus in the final product, it being understood that this level of biomass can be at least 6-7% in a polyurethane foam obtained according to the invention, and preferentially be between 7 and 20%. This percentage takes into account the actual weight of biomass, before the alkoxylation reactions. Such a percentage can in practice be found by using carbon-14 tests and / or chemical analysis of the foam composition (ASTM D6866-08). Here and in what follows, the term "vegetable oil" refers to a compound based on post-growth raw materials. According to a more specific feature of the invention, and without limitation, the mixture of alkoxylated polyols may comprise: 8 to 23% by weight relative to the total weight of the mixture of alkoxylated polyols of said first vegetable oil alcooxylated with a subscript hydroxyl between 26 and 80; From 2 to 5% by weight relative to the total weight of the alkoxylated polyol mixture of said second alkoxylated vegetable oil with a hydroxyl number of between 150 and 400; and optionally at least one additional alkoxylated polyol, in particular when the proportion by weight relative to the total weight of the mixture of alkoxylated polyols of said polyoxyethylene-polyoxypropylene polyol is between 60 and 77%. The reaction mixture may have a weight ratio of isocyanate composition / polyol mixture of 0.3 / 1 to 0.8 / 1. The isocyanate composition has a total free NCO content greater than 10%, for example greater than 15%, and preferably between 20 and 42%. Suitable isocyanates include MDI and TDI. The isocyanates can be used in pure form, that is to say unpolymerized, and / or in prepolymerized form. The isocyanate composition may further comprise isocyanate derivatives containing carbodiimide, uretonimine, isocyanurate, urethane, alophanate, urea and / or biuret groups. Suitable surfactants are, for example, siloxanes. The reaction mixture may comprise other additives, such as crosslinking agents, flame retardants, such as halogenated alkyl phosphates, foam stabilizers, fillers and / or pigments. The crosslinking agents may be chosen from short-chain polyols having a molecular weight of less than 1000, such as diols or triols, diamines or diamino alcohols. Foam stabilizers are used to stabilize or regulate the cells of the foam. Suitable foam stabilizers are, for example, polysiloxane-polyalkylene oxide block copolymers. The respective amounts of catalyst, surfactant and optionally other additives used depend on the nature of the product used and can be adopted by those skilled in the art of polyurethane foams. The water present in the reaction mixture serves as a blowing agent. Advantageously, 1 to 10%, preferably 1 to 5% by weight of water relative to the total weight of the polyol mixture is used. Surprisingly in view of the use of bio-polyols, the process uses catalysts usually employed for the preparation of polyurethane foams, for example catalysts of the gas or gel type. The catalyst can thus be a LVOC (Low Volatile Organic Compound) reduced emission catalyst, that is to say corresponding to a common organic product and more expensive than their Non LVOC counterparts. This is contrary to a prejudice of those skilled in the art, since it is well known that LVOC catalysts deteriorate the aging resistance of foams. The deterioration is indeed more particularly accentuated when testing the durability in wet medium polyurethane foams of high resilience based on polyols of plant origin and obtained using LVOC catalysts. In preferred embodiments of the invention, one or more of the following provisions may also be used: the polyoxyethylene-polyoxypropylene polyol comprises a polyol having an oxyethylene content between 14 and 50% by weight, and preferably between 14 and 17% by weight. the mixture of alkoxylated polyols additionally comprises 1 to 5% by weight relative to the total weight of the polyol mixture of a polyoxyethylene-polyoxypropylene-polyol minority having a real nominal functionality of between 2 and 6, and whose oxyethylene content is from 80 to no% by weight relative to the total weight of the polyoxyethylene-polyoxypropylene minor polyol. the mixture of alkoxylated polyols comprises (for example in a proportion of at least 50% and preferably more than 65% by weight relative to the total weight of the polyol mixture) a polyoxyethylenepolyoxypropylene polyol grafted also called polyol copolymer, of average nominal functionality between 2 and 6, where the EO is present at the end of the chain, and whose total level of EO is less than 20% by weight, the primary hydroxyl function rate being at least 50%. It is possible to obtain, by the process according to the invention, a high-resilience polyurethane foam having very good resistance characteristics. Another object of the invention is to provide a seat element having a high resilience foam whose resistance characteristics correspond to the most stringent specifications while minimizing the portion of material derived from petrochemistry. For this purpose, there is provided a seat element, in particular for a motor vehicle, characterized in that it comprises a flexible polyurethane foam of high resilience according to the invention, this foam being preferably in a molded form. Such a seat element perfectly meets the most stringent requirements of car manufacturers. The invention will be better understood with the aid of the examples which follow, without these in any way limiting the scope.

Examples

The following compounds were used in the examples. The indication relating to the commercial product is not limiting in nature. The characteristics of the products using definitions well known to those skilled in the art (these definitions are also commonly used in patent applications, such as for example EP1842866, WO 2004/020497, FR2899230 or US6037382).

Table 1: Products used in the examples Product Characteristics Commercial product used Isocyanate Prepolymer based on 4,4'-Suprasec 1056 1 diphenylmethane diisocyanate (Huntsman) (MDI) with an NCO content between 20 and 42%. Polyol PO1 A polyoxyethylene-CP1421 polyoxypropylene polyol, Dow Chemicals) average nominal functionality between 2 and 6, where the EO is present at the end of the chain or randomly distributed, and whose total EO level is 80 to 100 Polyol PO2 a polyoxyethylene-polyoxypropylene polyol, of real average nominal functionality equal to 3, where the EO is present at the end of the chain or randomly distributed, and whose total EO level is between 17 and 50% by weight. The level of primary hydroxyl functions is at least 50%. Polyol a polyoxyethylene PO2 'polyoxypropylene polyol, Bayfit 10WF14 nominal functionality (Bayer) actual average greater than 3 and where the EO is present at the end of the chain or randomly distributed, and whose total level of EO is between 17 and 50% by weight. The level of primary hydroxyl functions is at least 50%. Polyol PO3 a polyoxyethylene-polyoxypropylene polyol, Lupranol (BASF) average nominal functionality 3 and where the EO is present at the end of the chain and whose total level of EO is between 14 and 17% by weight. The level of primary hydroxyl functions is at least 50%. The molecular weight is about 6000 Polyol PO4 a polyoxyethylene-NC700 (Dow polyoxypropylene polyol Chemicals) graft also called polyol copolymer, of average nominal functionality between 2 and 6, where the EO is present at the end of the chain, and whose total rate of OE is less than 20% by weight.

The level of primary hydroxyl functions is at least 50%. Polyol H1 Propoxylated and / or ethoxylated vegetable oil with a hydroxyl value of between 26 and 80. Polyol H2 Propoxylated and / or ethoxylated vegetable oil with a hydroxyl number of between 150 and 400 Additive PU45WB02 (Bayer) crosslinking Catalyst Catalyst second generation NE300 LVOC generation gas with reduced emissions. Second generation JeffCat 2130 LVOC gelling catalyst catalyst (Huntsman) NE1070 reduced emission (second generation novel non-emission catalyst). (NE) Gelling Silicone 1 Stabilizer / Regulator 8729 LF2 or Cell. EPK78 (Evonik) The hydroxyl number is expressed in a manner known per se in mg KOH / g. Poloyl PO2 'provides overall better results than the PO2 polyol, due to the greater nominal functionality (> 3).

Flexible HR polyurethane padding was prepared from the respective reaction mixtures of a first group of mixtures, as indicated below: Table 2: Compositions of the reaction mixtures in the first group of mixtures Composition Composition Composition Composition Xl X2 X3 X4 (in accordance with (comparative) (comparative) (comparative / invention) Non Bio) Polyol PO1 1 Polyol PO2 Polyol PO3 70 70 70 90 Polyol PO4 20 20 10 10 Bio-polyol 10 10 20 H1 Bio-polyol 4 H2 Catalyst 1 , 8 1.5 1.2 1.2 Gas LVOC Catalyst 1,3 1,2 1,2 1,4 Gel LVOC Additive 1 1 1 3 Crosslinking Silicone 1 0.4 Water 2.7 2.9 4.5 4 Table 2 shows weight indications. Thus, for 105 g of the mixture of alkoxylated polyols of the composition C1, about 9.5% by weight (based on the total weight of the alkoxylated polyol mixture) of the biopolyol H1 and about 4% by weight of the bio-polyol H2 are used. . The proportions of diisocyanates are not shown in this table.15 First example - composition Xl

A flexible polyurethane foam padding HR, here covered with a cap, is prepared in an in situ process for making an accessory such as a headrest from the reaction mixture shown in Table 2 (composition X1) above in a mold formed of a bottom and a lid. The process may of course be different, for example by preparing a padding without a cap (from the same reaction mixture). In the nonlimiting example of an in situ process, the cap is first placed in the bottom of the mold, visible upside down, and maintained by suction. Then the reaction mixture is poured directly onto the cap. At the same time the suction which held the cap is cut off. Then the lid is sealed. The lid / mold may not be heated due to the exothermic nature of the reaction. When the mold is used successively for the preparation of several padding, the heat in the mold due to the reaction can typically be sufficient. Otherwise it can be heated to a temperature of 50 ° C for example. Alternatively the temperature could be different for example between 50 ° C and 70 ° C.

The lid is reopened here after at most 240s. Eventually this period can be extended up to 300s according to the specific needs. The padding covered with a cap disposed in the bottom of the mold is dislodged. The characteristics of the resulting padding are then determined, which can be: - i) the density (kg / m3) according to DIN EN ISO 845; - ii) resilience (%) 4th cycle according to specification PV3427; - iii) lift / P4 / 40 according to specification PV3410; iv) the Cs lift loss test after autoclaving according to the specification DBL5452.05 (Daimler Benz); v) the loss of lift test Dp after autoclaving according to the specification DBL5452.05 (Daimler Benz); vi) Humid-Aged Compression Sets according to PV3410; vii) the 70% WCs test according to the PSA manufacturer's specification D411637; viii) the 70% Cs test according to the PSA manufacturer's specification D451046; (ix) the tear strength test (N / m) up to a threshold load of 150N, according to the PSA specification D411048.

The results are shown in Table 3 (X1). It is understood that the mold and the heating conditions can be chosen according to the desired application for the padding, without this generating a significant change in the properties of the material constituting the padding obtained. The reaction mixture with the composition X1 is for example usable for obtaining a component of a seat such as a headrest or an armrest. It should be noted that test vi) provides a stricter specification for a cushion (specification threshold: <15) than for a head restraint or armrest (specification threshold: <30). In the case of reaction mixtures of the first group, suitable for the design of a seat accessory such as a head restraint or an armrest, this is the highest threshold that applies for this test vi). In addition, tests vii and viii are not used for headrest and armrest applications. Second Example - Composition X2 (Comparative) The reaction mixture shown in Table 2 (composition X2) is similarly used to obtain a pad of polyurethane foam. The reaction mixture with the composition X2 can be used to obtain a component of a seat such as a headrest or an armrest. The same characteristics as in the first example are then determined. The results are shown in Table 3 (X2). Third example - composition X3 (comparative)

The reaction mixture shown in Table 2 (composition X3) is similarly used to obtain polyurethane foam padding. The reaction mixture with the composition X3 can be used to obtain a component of a seat such as a headrest or an armrest. The same characteristics as in the first example are then determined. The results are shown in Table 3 (X3). Fourth Example - Composition X4 (Comparative) The reaction mixture shown in Table 2 (composition X3) is similarly used to obtain a pad of polyurethane foam. In this case, no bio-polyol is used. The reaction mixture with the composition X4 can be used to obtain a component of a seat such as a headrest or an armrest.

The same characteristics as in the first example are then determined. The results are shown in Table 3 (X4). Table 3: Results for the first group of mixtures The values in accordance with the specifications (tests iv) at ix)) appear in bold type in this table. The "Not measurable" statement relates the state of a fully hydrolysed foam and unsuitable for the evaluation of its physical properties. Characteristics Specification Xl X2 X3 X4 or threshold i) 60 58 35 30 ii) 75 73 73 74 iii) 4,6 4,2 5,4 5,8 iv) <21 18 39 No Not measurable measurable v) <40 13 25 No Not measurable measurable vi) <30 - 20 - - - - (ix)> 150 152 146 155 120 An advantage of the foam produced according to the invention (see first For example, with the mixture X1), the use of bio-polyols surprisingly contributes to achieving high performance (see Table 3) even using an "in-situ" process with a "reduced emission" catalyst. LVOC. In particular, the resilience performance is at least equal, while the loss of lift is significantly reduced. It is furthermore noted that such a foam satisfies all the particularly severe tests indicated above. The use of two alkoxylated organic oils having different hydroxyl numbers makes it possible to obtain a content well above 2% by weight relative to the total weight of the mixture of alkoxylated polyols, with a content preferably ranging from range ranging from 10 to 28%, and even more preferably between 10 and 22% for obtaining optimal performance. In the case of composition X1, the first oil with a hydroxyl number of between 26 and 80 is the predominant oil and can significantly reduce the content of polyols of petrochemical origin. This first oil and the second oil are optionally propoxylated vegetable oils.

Table 4: Compositions of the reaction mixtures in the second group of mixtures Composition Y1 Composition Composition (according to Y2 Y3 the invention) (comparative) (comparative / Non Bio) Polyol PO1 3 3 6 Polyol PO2 25 Polyol PO3 85 85 59 Polyol PO4 Bio-Polyol H1 15 Bio-Polyol H2 3 Catalyst 0.7 0.5 0.6 LVOC Gas Catalyst 0.6 0.6 0.6 Gel LVOC Additive 1 1 1.2 Crosslinking Silicone 1 0.4 0, 7 0.8 Water 3.4 3.4 3.2 Table 4 above shows weight indications. With the composition Y1, the overall percentage of H1 and H2 bio-polyols is a little higher than for the composition X1. Fifth Example - Composition Y1 A capped HR flexible polyurethane foam padding is prepared in an in situ process for making a cushion or the like from the reaction mixture shown in Table 4 (composition Y1) above in a mold formed of a bottom and a lid. First the cap is placed in the bottom of the mold, upside down visible, and maintained by suction. Then the reaction mixture is poured directly onto the cap. At the same time the suction which held the cap is cut off.

Then the lid is sealed. The lid / mold is heated to a temperature of 50 ° C for example, preferably without exceeding 70 ° C. The lid is reopened after at most 300s. The padding covered with a cap disposed in the bottom of the mold is dislodged. It can be noted here that the polymerization time remains short, which is an advantage in terms of productivity and cost of production. Of course, the experiment could as well be carried out with a more conventional method by preparing a quilting without a cap from the same reaction mixture. Characteristics i) to ix) of the padding obtained are then determined.

The results are shown in Table 5 (Y1). It is understood that the mold can be chosen according to the desired application for padding. The reaction mixture with the composition Y1 is for example usable for obtaining a seat element such as a cushion.

Sixth Example - Composition Y2 (Comparative)

The reaction mixture shown in Table 4 (Composition Y2) is similarly used to obtain polyurethane foam padding. The reaction mixture with the composition Y2 can be used to obtain an element of a seat such as a cushion.

The same characteristics as in the fifth example are then determined. The results are shown in Table 5 (Y2).

Seventh Example - Composition Y3 (Comparative) The reaction mixture shown in Table 5 (Composition Y3) was similarly used to obtain polyurethane foam padding. The reaction mixture with the composition Y3 can be used to obtain an element of a seat such as a cushion. The same characteristics as in the first example are then determined.

The results are shown in Table 5 (Y3). Table 5: Results for the second group of mixtures Values according to the specifications appear in bold in this table. Characteristics Specification Y1 Y2 Y3 or threshold i) 58 56 59 ii) 85 83 85 iii) 6.3 6.3 6.3 iv) <21 17 14 13 v) <40 35 48 51 vi) <15 7 6 8 vii <15 12 10 11 viii) <20 7 9 10 ix)> 150 146 145 150 The foam produced according to the invention (see the fifth example with the Y1 mixture) has surprisingly high performances (see Table 5). even using an "in situ" process with a "reduced emission" LVOC catalyst. It can be seen here that the resilience performance is at least equal, while the loss of lift is lower, the foam in particular passing the test v) (loss of lift Dp after autoclaving according to the specification DBL5452.05 of Daimler Benz) . It is furthermore noted that such a foam satisfies all the particularly severe tests indicated above.

Table 6: Compositions of the reaction mixtures in the third group of mixtures Composition Zl Composition Composition (according to Z2 Z3 the invention) (comparative) (comparative / Non Bio) Polyol PO1 2,5 2,5 6 Polyol PO2 88 90 25 Polyol PO3 69 Polyol PO4 Bio-polyol H1 12 10 Bio-polyol H2 4 Catalyst 0.7 0.7 0.5 Gas LVOC Catalyst 0.7 0.7 0.5 Gel LVOC Additive 0.4 2 Crosslinking Silicone 1 0.5 0.5 0.8 Water 3.23 3.23 2.81 Table 6 shows weight indications.

In this third group, comparatively less water is used than in the second group of mixtures (see Table 4, last line). It is intended here to use polyol B1 without addition of polyol D. Moreover, the form of the padding differs here from the second group, this form being conducive to an increase in density of polyurethane foams. It is found that the density is higher with the padding form made using the mixtures of the third group, as shown in Table 7 (see characteristic i)). The density and shape obtained in this third group make padding typically more suitable (but not exclusively) for application to seat backs. With composition Z1, the overall percentage of biopolyols H1 and H2 is a little higher than for composition X1.

Eighth example - composition Z1

In this non-limiting example of the molding process, a capped HR flexible polyurethane foam padding is prepared here in an in situ process for making a pad from the reaction mixture shown in Table 6 (composition Z1). above in a mold formed of a bottom and a lid.

First the cap is placed in the bottom of the mold, upside down visible, and maintained by suction. Then the reaction mixture is poured directly onto the cap. At the same time the suction which held the cap is cut off. Then the lid is sealed. The lid / mold is heated to a temperature of 50 ° C for example, preferably without exceeding 70 ° C. The lid is reopened after at most 300s. The padding covered with a cap disposed in the bottom of the mold is dislodged. Characteristics i) to ix) of the padding obtained are then determined. The results are shown in Table 7 (Z1). Of course, the experiment could as well be carried out with a more conventional method by preparing a quilting without a cap from the same reaction mixture. It is understood that the mold can be chosen according to the desired application for padding. The reaction mixture with the composition Z1 is for example usable for obtaining an element of a seat such as a backrest or cushion.

Ninth Example - Composition Z2 (Comparative) The reaction mixture shown in Table 6 (Composition Z2) was similarly used to obtain polyurethane foam padding. The reaction mixture with the composition Z2 can be used to obtain a seat element such as a backrest or cushion.

The same characteristics as in the eighth example are then determined. The results are shown in Table 7 (Z2).

Tenth Example - Composition Z3 (Comparative)

The reaction mixture shown in Table 6 (Composition Z3) was similarly used to obtain polyurethane foam padding. The reaction mixture with the composition Z3 can be used to obtain an element of a seat such as a backrest or cushion. The same characteristics as in the first example are then determined. The results are shown in Table 7 (Z3).

Table 7: Results for the third group of mixtures Values according to the specifications appear in bold in this table. Characteristics Specification Zl Z2 Z3 or threshold i) 71 70 68 ii) 85 83 85 iii) 7.5 8.3 8.3 iv) <21 18 18 14 v) <40 33 68 55 vi) <15 7 8 9 vii The foam made according to the invention (see eighth example with the Z1 mixture) surprisingly has high performances. (see Table 7) even using an "in situ" process with a "reduced emission" catalyst LVOC. It can be seen here that the resilience performance is at least equal, while the loss of lift is lower, the foam in particular passing the test v) (loss of lift Dp after autoclaving according to the specification DBL5452.05 of Daimler Benz) . It is furthermore noted that such a foam satisfies all the particularly severe tests indicated above. It should be obvious to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed.

Claims (10)

REVENDICATIONS1. A process for producing a high resilience flexible polyurethane foam in which a reaction mixture comprising an isocyanate composition including at least one polyisocyanate, a mixture of alkoxylated polyols, a crosslinking additive, water and at least one a catalyst, the mixture of alkoxylated polyols comprising: 60 to 90% by weight based on the total weight of the mixture of alkoxylated polyols of at least one polyoxyethylene polyoxypropylene polyol having a primary hydroxyl functional group level of greater than or equal to 50% with a functionality actual nominal in the range of 2.5 to 6, and preferably at least 3; and two alkoxylated vegetable oils of which the first alkoxylated oil is, in relation to the second alkoxylated oil, in greater proportion by weight and has a hydroxyl number of not more than 100, the second alkoxylated oil having an hydroxyl number of at least equal to 150, the cumulative proportion of the first and second alkoxylated oils being preferably in the range of 10 to 28% by weight relative to the total weight of the alkoxylated polyol mixture. The process according to claim 1, wherein the alkoxylated polyol mixture comprises: 8 to 23% by weight based on the total weight of the alkoxylated polyol mixture of said first alkoxylated vegetable oil with a hydroxyl number between 26 and 80; 2 to 5% by weight based on the total weight of the alkoxylated polyol mixture of said second alkoxylated vegetable oil with a hydroxyl number between 150 and 400; and optionally at least one additional alkoxylated polyol, in particular when the proportion by weight relative to the total weight of the mixture of alkoxylated polyols of said polyoxyethylene-polyoxypropylene polyol is between 60 and 77%. 3. Method according to one of claims 1 and 2, wherein the weight ratio isocyanate composition / polyol mixture is 0.3 / 1 to 0.8 / 1. 4. Method according to one of claims 1 to 3, wherein the isocyanate composition has a total free NCO content greater than 15%, and preferably between 20 and 42%. 5. Method according to one of claims 1 to 4, wherein said at least one polyoxyethylene-polyoxypropylene polyol comprises a polyol having an oxyethylene content of between 14 and 50% by weight, and preferably between 14 and 17% by weight. . 6. Process according to one of claims 1 to 5, wherein the mixture of alkoxylated polyols further comprises 1 to 5% by weight relative to the total weight of the polyol mixture of a polyoxyethylene-polyoxypropylene polyol minority having a nominal functionality. between 2 and 6, and whose oxyethylene content is 80 to no% by weight relative to the total weight of the polyoxyethylene-polyoxypropylene polyol minority. 7. Method according to one of claims 1 to 6, wherein the catalyst is of the gas or gel type. 8. The method of claim 2 alone or taken in combination with any one of claims 3 to 7, wherein is used as additional alkoxylated polyol a polyoxyethylene-polyoxypropylene polyol graft, also called polyol copolymer, of actual nominal functionality between 2 and 6, where the oxyethylene is present at the end of the chain, and whose total content of oxyethylene is less than 20% by weight, the primary hydroxyl function level being at least 50%. 9. A high resilience flexible polyurethane foam obtained according to any one of claims 1 to 8. Seat element, in particular for a motor vehicle, characterized in that it comprises a high-resilience flexible polyurethane foam according to claim 9, said foam preferably being in a molded form.