CH706685A2 - improved support structure for the human body. - Google Patents

Abstract

A support structure for the human body comprises a shell (2) to which a padding (4) in turn covered by a covering (7) is superposed. The padding (4) and / or the lining (7) are made with a formulation comprising at least one polymeric material of fossil derivation and at least one material derived from renewable sources and the materials of the formulation are selected in such a way that the imprint of carbon according to the ISO 14067 standard in terms of equivalent carbon dioxide quantity (CO 2 e) per unit weight of the formulation is relatively low and the percentage of radiocarbon 14 (pMC) according to the ASTM D6866 standard per unit weight of the formulation is relatively high. The formulation for the realization of the lower layer (5) of the padding (4) comprises an expanded polymeric preparation comprising a polyol phase, an isocyanate phase, an additive phase, and a plasticizer phase, in which the additive phase includes additives derived from fossil sources and derived from renewable sources, the latter comprising additives selected from the group which includes plasticizers derived from hydrogenated castor oil, crosslinkers, catalysts, expanding agents, and in which said plasticizers are derivatives of hydrogenated castor oil.

Description

[0001] Sector of application The present invention is generally applicable to the technical field of support devices for the human body and particularly relates to an improved and eco-responsible support structure.

State of the art

[0002] It is known that support devices for the human body, such as saddles for bicycles or pedal machines, such as for example an exercise bike and spinning bikes, but also seats and armrests of machines in general, generally have a formed structure. by at least one hull intended to be fixed on the frame of the machine, a padding superimposed on the hull and a covering intended to cover the padding and to come into contact with the user's body.

Technical problem

[0003] Patent application CH-A-716/12 in the name of the same Applicant describes a support structure for the human body, such as a saddle or a seat for a similar vehicle or machine, essentially comprising a hull, a padding superimposed on the hull and a covering able to cover the padding. The padding and / or the covering are made with a formulation comprising at least one polymeric material of fossil derivation and at least one material derived from renewable sources.

[0004] The materials of the aforementioned formulation are selected in such a way that the carbon footprint according to the ISO 14067 standard in terms of carbon dioxide equivalent amount per unit weight of the formulation is relatively low and the radiocarbon percentage 14 according to the ASTM D6866 standard per unit weight of the formulation is relatively high.

[0005] Furthermore, the formulation used for making the lower layer of the padding comprises an expanded polymeric preparation comprising a phase of polyols, an isocyanate phase, an additive phase, and a plasticizer phase.

[0006] Still, the additive phase includes additives derived from fossil sources and derivatives from renewable sources, in which the aforesaid derivatives from renewable sources comprise additives selected from the group which includes plasticizers, crosslinkers, catalysts, expanding agents, and components of the known structures of support of the type indicated above and present on the market are generally made of polymeric materials of fossil origin and in which, preferably, the plasticizers are derived from castor oil.

[0007] In mechanical terms, the comfort of the saddle as a whole can be associated with its compliance or resilience. While the hull is designed to support the weight of the user and is therefore made of a relatively rigid or semi-rigid plastic material, such as for example high-density polyethylene, polypropylene, polyethylene, polyamide, PVC and other similar resins, the padding and the coating is aimed at giving the saddle the desired comfort. Since these components are superimposed on each other, and therefore connected in series, the yield and therefore the resulting comfort is given by the sum of the inverse of the stiffness of the individual components of the saddle depends on the stiffness of the individual components depends on the modulus of elasticity of the base material, by the thickness and by the state of residual tension. In general, the polymeric materials used are selected from those with a relatively low modulus of elasticity, ie with a relatively low Shore hardness.

[0008] Such "soft" materials are obtained by mixing various polymers in the liquid state, some of which have plasticizer functions. In general, a plasticizer is a compound of molecules much smaller than the macromolecules of the polymer, so that it can be inserted more homogeneously between the macromolecules during mixing. In addition, the plasticizer must be completely miscible with the polymer, so as to be stably and homogeneously incorporated into its mass and does not tend to migrate towards the surface of the plastic material over time (a phenomenon known as "exudation"). The plasticizer must also be little or not at all volatile, that is, have a high boiling point, because leaving the plastic material, its effect would fail.

[0009] A problem of these known formulations is that the plasticizers containing castor oil in the pure state, or ricinoleic acid, can be particularly compact and characterized by high hardness, for example of the order of 60 Shore C.

[0010] It follows that the padding may be less comfortable for users.

Presentation of the invention

[0011] A general purpose of the present invention is to overcome the aforementioned drawbacks by providing a support structure for the human body with eco-responsible characteristics, reduced environmental impact, comfort, durability and economy.

[0012] A particular purpose is that of realizing an eco-responsible support structure for the human body realized with materials having the maximum content from renewable sources and having as a whole a low carbon footprint so as to contribute to an eco-friendly development. responsible.

[0013] A further object is to provide a support structure for the human body that has the lowest environmental impact by reducing the use of synthetic materials derived from fossil sources.

[0014] Another object is to provide a support structure for the human body which has characteristics of high softness and mechanical characteristics, in particular low loss of lift at dynamic fatigue and high resilience.

[0015] These objects, as well as others which will become clearer below, are achieved by a support structure for the human body in accordance with the main claim.

Brief description of the drawings

[0016] Further characteristics and advantages of the invention will become more evident in the light of the detailed description of some preferred but not exclusive embodiments of a support structure for the human body, for example a bicycle saddle according to the invention, illustrated by way of non-limiting example with the aid of the attached drawing tables in which: fig. 1 is a perspective view of a support structure, in particular a bicycle saddle according to the invention; fig. 2 shows the saddle structure of fig. 1 partially sectioned to highlight its main components; fig. 3 shows a plan view of the saddle structure of Fig. 1; fig. 4 shows a view of the saddle structure of Fig. 3 sectioned along a longitudinal plane of line IV – IV; fig. 5 shows a view of the saddle structure of Fig. 3 sectioned according to a transversal plane of track V – V.

[0017] Detailed description of embodiments With reference to the above figures, a support structure for the human body is shown, in particular a saddle for cycles, motorcycles or pedal machines, such as for example an exercise bike for outdoor or indoor exercise.

[0018] In this case, the saddle has a substantially elongated conventional shape, with an axis of longitudinal symmetry, a tapered front portion intended to support the scrotal or inguinal region of the user and an enlarged posterior portion intended to support the ischial region of the same user.

[0019] Alternatively, the support structure may also have a different shape, such as for example that of a seat, an armrest or a headrest for a vehicle of any type, such as a motor vehicle, a boat, an airplane, a car for work, without departing from the scope of the invention.

[0020] The saddle structure, generally indicated with the reference number 1, comprises a support hull 2 which can be anchored to a frame 3 intended to be fixed to a bicycle or similar vehicle.

[0021] On the shell 2 there is provided a padding, generally indicated 4, which comprises a lower layer 5 of an expanded polymer to which at least a layer 6 is at least partly superimposed, at least in part with memory of a polymer in the form of a gel.

[0022] On the padding 4 a covering 7 is made which is intended to cover the upper surface of the padding and come into contact with the user's body.

[0023] The shell 2 is of the conventional type and is made of synthetic material, for example high density polyethylene, polypropylene, polyethylene, polyamide, PVC and other similar polymeric materials. Preferably the shell 2 can be made of polypropylene.

[0024] Preferably the upper layer 6 of the padding can be made with a polyurethane or silicone gel.

[0025] Preferably, the coating 7 contains polymeric materials of the type PVC, thermoplastic polyurethane, polyurethane, Pebax ® ® derived from PAll-Polyamide 11.

[0026] Without prejudice to the conventional nature of the polypropylene shell, according to the invention, to make the support eco-responsible, the padding 4 and the covering 7 can be made with a formulation comprising at least one polymeric material of fossil derivation and at least one material derived from renewable sources.

[0027] With particular reference to the components of the padding 4, they are generally constituted by a foam and a gel which, according to what has been previously said, are generally of a polyurethane nature, i.e. formed by chains of polymers formed by urethane bonds.

[0028] It is known that urethane or PU polymers are obtained by reacting a di-isocyanate (aromatic or aliphatic) and a polyol (polyethylene glycol or polyester) in the presence of catalysts and other additives to give the material the desired characteristics. If said polyol materials are added with so-called "expanding" materials, it is possible to obtain expanded polyurethanes.

[0029] Foamed PUs may be in the form of flexible soft PUs, integral soft or self-pelleting PUs, semi-rigid PUs, rigid / structural PUs, compact rigid PUs and compact elastic PUs.

[0030] In general, two mechanisms are involved in the production of polyurethane foams: the first is the reaction of the isocyanate, present in excess, with the hydroxyl groups of the polyol, the second produces the swelling gas and gives rise to the structure of the expanded foam .

[0031] This last process can be of chemical or physical nature: in the first case, the basic reaction of the synthesis is paired with that of the isocyanic group with water and in this way the foam is obtained from the formation of urethane bonds and from the simultaneous unfolding of carbon dioxide gas resulting from the reaction with water. Physical expansion, on the other hand, uses part of the heat from the polymerization reaction to vaporize a chemically inert liquid (swelling agent) with a low boiling temperature.

[0032] As expanding agents, products are currently used such as hydrochlorofluorocarbons (HCFC), used in combination with water or alone. The expanding agent is added to the polyols and its action is manifested by the vaporization induced by the heat developed by the main reaction which is exothermic. All other additives and catalysts are also added to the polyols.

[0033] The two most widely used isocyanates in the manufacture of these foams are the TDI (toluene di-ispianate) and MDI (diphenylmethanediisocyanate polymer) isomers. Generally an 80/20 mixture of the two TDI isomers is used for the synthesis of flexible foams, while the MDI is more widely used in the production of rigid foams.

[0034] In general, in the seats and in the saddles for bicycles, integral self-beading expanded foams are used. These foams are characterized by an internal cellular structure and a non-cellular external surface, and are made in a mold by a single operation. The principle of their synthesis is the use, as swelling agent, of halogenated hydrocarbons, without water, as well as in the use of molds with cold metal walls. At the moment of contact between the foam and the cold wall of the mold the condensation of the swelling occurs at the working pressure (1–4 bar). This causes a solid external coating to form, while inside the reaction mixture remains warm and polymerizes forming the foam. Oligomer polyols with a molecular weight between 3000 and 6500 are used, while for the isocyanate the choice is bound to the type of process. In general, TDI isocyanates are used in the bicycle saddle industry.

[0035] The formulation used for the realization of the padding 4 and of the lining 7 of the support 1 for the human body comprises at least one polymeric material of fossil derivation and at least one material derived from renewable sources.

[0036] Preferably, the amount of polymeric materials derived from renewable sources contained in the formulation is between 5% and 60% and is preferably between 10% and 40% and is still more preferably between 15% and 35% by weight.

[0037] A peculiar characteristic of the invention consists in the fact that the materials contained in the aforementioned formulation are selected in such a way that the carbon footprint according to the ISO 14067 standard in terms of equivalent carbon dioxide (CO2e) quantity is relatively low and the percentage of radiocarbon 14 (pMC) according to the ASTM D6866 standard is relatively high.

[0038] With specific reference to the padding 4, the amount of carbon dioxide equivalent (CO2e) associated with lkg of formulated for the realization of the padding is <9.5kg, is preferably between 9.3kg and 9kg and is even more preferably between 4.9kg and 3.5kg.

[0039] Furthermore, the percentage of radiocarbon 14 (pMC) associated with lkg of formulation of the padding 4 is> 0.01%, is preferably between 60% and 5% and is still more preferably between 40% and 10% .

[0040] With specific reference to coating 7, the amount of carbon dioxide equivalent (CO2e) associated with lkg of formulated for making the coating is <9.5kg, it is preferably between 9.3kg and 9kg and is even more preferably between 3.6kg and 2kg.

[0041] Furthermore, the percentage of radiocarbon 14 (pMC) associated with lkg of formulation of the coating 7 is> 0.01%, is preferably between 70% and 30% and is still more preferably between 60% and 40%.

[0042] With specific reference to the padding 4, the lower layer 5 can be a foam obtained with an expanded polymeric preparation, such as an expanded polyurethane suitable for making a performing product.

[0043] Suitably, the aforementioned polyurethane foam is selected with a relatively low Carbon Footprint value and a relatively high pMC radiocarbon value.

[0044] The aforementioned polyurethane preparation is obtained by mixing a polyol phase composed of a blend of polyols for integral PU and flexible PU with different molecular weight, an isocyanate phase composed of a blend of isocyanates for integral PU and for flexible PU, a phase of additives from fossil sources and renewable sources.

[0045] Preferably, the polyols for integral PU have a molecular weight between pm = 4000 and pm = 7000 and preferably equal to about pm = 4500, and the flexible PU polyols have a molecular weight of between 5000 and 6500 and preferably equal to at about pm = 6000.

[0046] The percentage by weight of the total polyols per integral PU with pm = 4500 is preferably between 40% and 0.01% and more preferably between 25% and 15% and even more preferably between 17% and 5%.

[0047] The percentage by weight of the total polyols for flexible PU with pm = 6000 is preferably between 35% and 0.01% and more preferably between 25% and 10% and even more preferably between 21% and 5 %.

[0048] The percentage by weight of the total isocyanates for integral PU is preferably between 30% and 10% and more preferably between 25% and 15% and even more preferably between 20% and 3%.

[0049] The percentage by weight of the total isocyanates for flexible PU is preferably between 20% and 0.01% and more preferably between 15% and 5% and even more preferably between 10% and 3%.

[0050] The percentage by weight of the total of the additives from fossil sources is preferably between 15% and 0.01% and more preferably between 10% and 5% and even more preferably between 6% and 5%.

[0051] A significant boost to the use of materials from renewable sources also in the production of expanded polyurethane foams derives from the identification of alternative "bio-based" additives that present lower costs than those of synthetic additives.

[0052] In this regard, in the polyol-based formulations for integral foams and for flexible foams, it is possible to select biological additives selected from glucides (carbohydrates), in particular among the disaccharides.

[0053] Saccharose can be selected from the disaccharides in the form of "icing sugar".

[0054] As is known, sucrose, C6H12O6, is formed by the reaction of a glucose molecule with a fructose molecule and the release of a water molecule. The hydroxyl groups of sucrose bind to those of the isocyanate thus contributing to the polymerization of the polyurethane mixture.

[0055] The amount of "icing sugar" that can be inserted into the polyol-based formulation cannot be raised indiscriminately since the percentage increase of this bio-based additive corresponds to an increase in lift and a reduction in resilience.

[0056] From an economic point of view, the use of this bio-based additive is favored by the reduced cost of the material, around 1 Euro / kg.

[0057] Furthermore, the additives derived from renewable sources may comprise additives selected from the group comprising plasticizers, crosslinkers, catalysts, expanding agents.

[0058] In particular, the plasticizers may comprise ricinoleic acid whose percentage by weight with respect to the total will be between 15% and 18% and preferably close to 17%.

[0059] By way of example, ricinoleic acid can be inserted by mixing the other components of the padding with 4 castor oil as it is.

[0060] However, it has been experimentally observed that the use of castor oil as such leads to the production of so-called "compact" polyurethane compounds with Shore C hardness measured according to the ASTM 2240 standard close to 60.

[0061] Therefore, the padding 4 thus obtained does not appear to be sufficiently comfortable as it has relatively high density and hardness.

[0062] Experimentally it has instead been observed that the use of plasticizers containing hydrogenated castor oil, both for the lower part 5 of the padding 4 and for the gel 6, improves the mechanical characteristics and the softness of the support padding, increasing the comfort for the user.

[0063] Particularly advantageous results have been obtained by using plasticizers comprising acetylated monoglycerides, in particular derived from fully hydrogenated castor oil.

[0064] A preferred component may be the acetic ester of the monoglyceride (also called acetylated monoglyceride) with CAS number 736150-63-3.

[0065] The use of the aforementioned additives will allow to have a lower layer 5 with Shore C hardness measured according to the ASTIVI 2240 standard between 30 and 50 and preferably between 40 and 45, and an upper layer 6 having Shore C hardness measured according to the ASTM 2240 standard between 1 and 10 and preferably close to 5.

[0066] The percentage by weight of the total of the additives from renewable sources is preferably between 55% and 0.01% and more preferably between 45 and 10% and even more preferably between 33% and 10%.

[0067] The percentage by weight of the total plasticizers from renewable sources is preferably between 30% and 0.01% and more preferably between 25% and 5% and even more preferably between 17% and 5%.

[0068] The percentage by weight of the total inert fillers from renewable sources is between 25% and 0.01% and more preferably between 20% and 5% and even more preferably between 16% and 5%.

[0069] With reference to the upper layer 6 of the padding 4, it can comprise a polyurethane gel having a relatively low Carbon Footprint value and a relatively high pMC radiocarbon value.

[0070] In particular, the polyurethane gel can be obtained by mixing a polyol phase comprising a polyol for flexible PU with molecular weight pm = 6000, an isocyanate phase composed of a blend of isocyanates for integral PU and flexible PU with the addition of a phase of fossil additives and a phase of additives from renewable sources.

[0071] In particular, the total weight percentage of polyols for flexible PU with pm = 6000 may be between 95% and 25%, more preferably between 70% and 50% and even more preferably between 60% and 5%.

[0072] The percentage by weight of the total of the additives from fossil sources is preferably between 2% and 0.01% and more preferably between 1.75% and 0.25% and even more preferably between 1% and 0.5%

[0073] The percentage by weight of the total of the additives from renewable sources is preferably between 70% and 0.01% and more preferably between 45% and 25% and even more preferably between 35% and 5%.

[0074] The percentage by weight of the total isocyanates for integral PU is preferably between 5% and 0.01% and more preferably between 4% and 1% and even more preferably between 2.5% and 1%.

[0075] The percentage by weight of the total isocyanates for flexible PU is preferably between 2% and 0.01% and more preferably between 1.75% and 0.25% and even more preferably between 1% and 0.5% .

[0076] With the configuration of the product object of the present invention it is possible to realize supports for the human body, and in particular bicycle saddles characterized by a content of materials from renewable sources (bio-based) up to 44% more than analogues competitor products, such as for example the saddle structure described and claimed in the European application EP 2 139 751.

[0077] It is also possible to make saddles that have an equivalent carbon-footprint content (CO2e) of approximately 2.94kg per kilogram of saddle weight against 4, llkg per kilogram of weight of similar products on the market such as, for example, the aforementioned saddle structure described and claimed in EP2 139 751.

[0078] In other words, similar saddles available on the market of the aforementioned type have a carbon-footprint that is greater than 40% of that of saddles made according to the teachings of the invention.

[0079] Two examples of polyurethane foam are provided below for the lower layer 5 of the filling obtained with commercially available products of Dow Chemical, with different percentages of polymeric materials derived from renewable sources, according to the following percentages calculated on 100% of the weight of the polyurethane formulation. <tb> EXAMPLE 1 <tb> A) POLIOLO phase <sep> <sep> <tb> Al) SPECFLEX NR 961 <sep> <sep> <tb> A.1.1 - SPECFLEX NR 914 (Prepared for INTEGRAL) <sep> <sep> <tb> INTEGRAL POLYOLUS phase with pm = 4500) <sep> <sep> <tb> <sep> VORANOL CP 4711 (69%) <sep> 16.48% <tb> <sep> SPECFLEX NC 700 (13%) <sep> 3.10% <tb> Additives for INTEGRAL PU <sep> <sep> <tb> <sep> MONOETHYLENE GLYCOL (crosslinker) <sep> 2.31% <tb> <sep> WATER (expanding) <sep> 0.11% <tb> <sep> VORALUX HT 326 (catalyst) <sep> 0.11% <tb> <sep> PLS 912 BLACK (coloring pigment) <sep> 0.88% <tb> <sep> SOLKANE 245 (expanding) <sep> 0.88% <tb> A.1.2) Prepared for FLEXIBLE <sep> <sep> <tb> PIPE FLEXIBLE Phase with pm = 6000 <sep> <sep> <tb> <sep> VORANOL CP 6001 <sep> 23.88% <tb> Additives for PU FLEXIBLE <sep> <sep> <tb> <sep> MONOETHYLENE GLYCOL (crosslinker) <sep> 1.67% <tb> <sep> WATER (expanding) <sep> 0.08% <tb> <sep> VORALUX HT 326 (catalyst) <sep> 0.08% <tb> <sep> PLS 912 BLACK (coloring pigment) <sep> 0.64% <tb> <sep> SOLKANE 245 (expanding) <sep> 0.64% <tb> A.2) RENOVABLE source phase <sep> <sep> <tb> A.2.1) Preparation with PLASTIFICANT function <sep> <sep> <tb> <sep> RECINOLEIC acid <sep> 17.80% <tb> Additives for INTEGRAL / FLEXIBLE PU <sep> <sep> <tb> <sep> MONOETHYLENE GLYCOL (crosslinker) <sep> 0.57% <tb> <sep> VORALUX HT 326 (catalyst) <sep> 0.14% <tb> <sep> SOLKANE 245 (expanding) <sep> 1.13% <tb> B) ISOCYANATE phase: SPECFLEX NE 432 <sep> <sep> <tb> SPECFLEX NE 135 (isocyanate for FLEXIBLE) <sep> <sep> 19.70% <tb> SPECFLEX NE 145 (isocyanate for INTEGRAL) <sep> <sep> 9.80% <tb> EXAMPLE 2 <tb> A1) SPECFLEX NR961 <sep> <sep> <tb> A.1.1 - SPECFLEX NR 914 (Prepared for INTEGRAL) <sep> <sep> <tb> INTEGRAL POLYOLUS phase with pm = 4500 <sep> <sep> <tb> <sep> VORANOL CP 4711 (69%) <sep> 12.14% <tb> <sep> SPECFLEX NC 700 (13%) <sep> 2.29% <tb> Additives for INTEGRAL PU <sep> <sep> <tb> <sep> MONOETHYLENE GLYCOL (crosslinker) <sep> 1.71% <tb> <sep> WATER (expanding) <sep> 0.08% <tb> <sep> VORALUX HT 326 (catalyst) <sep> 0.08% <tb> <sep> PLS 912 BLACK (coloring pigment) <sep> 0.65% <tb> <sep> SOLKANE 245 (expanding) <sep> 0.65% <tb> A.1.2) Prepared for FLEXIBLE <sep> <sep> <tb> PIPE FLEXIBLE Phase with pm = 6000 <sep> <sep> <tb> <sep> VORANOL CP 6001 <sep> 17.60% <tb> Additives for PU FLEXIBLE <sep> <sep> <tb> <sep> MONO-ETHYLENE COLE (cross-linker) <sep> 1.22% <tb> <sep> WATER (expanding) <sep> 0.06% <tb> <sep> VORALUX HT 326 (catalyst) <sep> 0.06% <tb> <sep> PLS 912 BLACK (coloring pigment) <sep> 0.46% <tb> <sep> SOLKANE 245 (expanding) <sep> 0.46% <tb> A2) RENOVABLE source phase <sep> <sep> <tb> Preparation PLASTIFYING <sep> <sep> <tb> <sep> RECINOLEIC acid <sep> 16.00% <tb> Additives for INTEGRAL / FLEXIBLE PU <sep> <sep> <tb> <sep> MONO-ETHYLENE GLYCOL (cross-linker) <sep> 0.20% <tb> <sep> VORALUX HT 326 (catalyst) <sep> 0.04% <tb> <sep> SOLKANE 245 (expanding) <sep> 0.40% <tb> Prepared with INERT CHARGE <sep> <sep> <tb> <sep> SUGAR SUGAR <sep> 16.00% <tb> B) ISOCYANATE phase: SPECFLEX NE 432 <sep> <sep> <tb> SPECFLEX NE 135 {isocyanate for FLEXIBLE) <sep> <sep> 19.70% <tb> SPECFLEX NE 145 (isocyanate for INTEGRAL) <sep> <sep> 9.80%

Claims (6)

1. A support structure for the human body, such as a saddle or a seat for a similar vehicle or machine, comprising: - a hull (2); - a padding (4) superimposed on said hull; - a coating (7) able to cover said padding (4); wherein said padding (4) and / or said coating (7) are made with a formulation comprising at least one polymeric material of fossil derivation and at least one material derived from renewable sources, wherein the materials of said formulation are selected such that the carbon footprint according to the ISO 14067 standard in terms of equivalent carbon dioxide (CO2e) per unit weight of the formulate is relatively low and the percentage of radiocarbon 14 (pMC) according to the ASTM D6866 standard per unit weight of the formulation is relatively high, wherein said formulation for the realization of the lower layer (5) of the padding (4) comprises an expanded polymeric preparation comprising a polyol phase, an isocyanate phase, an additive phase, and a plasticizer phase, wherein said additive phase comprises additives derived from fossil sources and derived from renewable sources, said additives derived from renewable sources comprising additives selected from the group which includes plasticizers, crosslinkers, catalysts, expanding agents, and wherein said plasticizers are derived from hydrogenated castor oil. 2. The structure according to claim 1, wherein said plasticizers comprise acetylated monolicides derived from hydrogenated castor oil. 3. Structure according to claim 2, wherein said lower layer (5) of said padding (4) comprises an expanded polymeric preparation with a polyurethane foam for integral PU and for flexible PU containing said plasticizers derived from hydrogenated castor oil. 4. Structure according to any one of the preceding claims, in which the quantity of materials of said formulate derived from renewable sources is between 5% and 60% and is preferably between 10% and 40% and is still more preferably between 15% and 35%. 5. Structure according to any one of the previous claims, wherein said plasticizers are present in said lower layer (5) so as to give the polyurethane foam a Shore C hardness measured according to the ASTM 2240 standard of between 30 and 50 and preferably between 40 and 45. 6. Structure according to any one of the preceding claims, wherein said upper layer (6) of the padding (4) comprises a polyurethane gel, said plasticizers being present in said polyurethane gel to give it a Shore C hardness measured according to the ASTM 2240 standard between 1 and 10 and preferably close to 5.