EP4308620A1 - Process for making a polyurethane gel - Google Patents

Process for making a polyurethane gel

Info

Publication number
EP4308620A1
EP4308620A1 EP22714242.9A EP22714242A EP4308620A1 EP 4308620 A1 EP4308620 A1 EP 4308620A1 EP 22714242 A EP22714242 A EP 22714242A EP 4308620 A1 EP4308620 A1 EP 4308620A1
Authority
EP
European Patent Office
Prior art keywords
polyurethane gel
expandable microspheres
process according
mixing
expansion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22714242.9A
Other languages
German (de)
French (fr)
Inventor
Stefano Grassini
Massimo GILARDI
Marco GUASCHINO
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TOSCANA GOMMA SpA
Original Assignee
TOSCANA GOMMA SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TOSCANA GOMMA SpA filed Critical TOSCANA GOMMA SpA
Publication of EP4308620A1 publication Critical patent/EP4308620A1/en
Pending legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
    • C08G18/76—Polyisocyanates or polyisothiocyanates cyclic aromatic
    • C08G18/7657—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings
    • C08G18/7664—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups
    • C08G18/7671—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups containing only one alkylene bisphenyl group
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/088—Removal of water or carbon dioxide from the reaction mixture or reaction components
    • C08G18/0885—Removal of water or carbon dioxide from the reaction mixture or reaction components using additives, e.g. absorbing agents
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C08G18/4825—Polyethers containing two hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C08G18/4829—Polyethers containing at least three hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
    • C08G18/76—Polyisocyanates or polyisothiocyanates cyclic aromatic
    • C08G18/7657—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/30—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by mixing gases into liquid compositions or plastisols, e.g. frothing with air
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/32—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof from compositions containing microballoons, e.g. syntactic foams
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2203/00—Foams characterized by the expanding agent
    • C08J2203/22—Expandable microspheres, e.g. Expancel®
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2375/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
    • C08J2375/04—Polyurethanes

Definitions

  • the present invention relates to a process for making a polyurethane gel of the type specified in the preamble of the first claim.
  • a gel is traditionally defined as a three-dimensional solid molecular network composed substantially of cross-linked polymers distributed in a gelatinous matrix of any shape or size and which does not exhibit steady-state flow.
  • the term "gel” is used here to describe a soft polyurethane with a gel-like consistency.
  • the polyurethane gel is comfortable to the touch and is capable of slowly returning to its original shape after deformation. In general, it is a solid and compact material. Such gels can be covered with a thin layer of elastomeric material to provide surface protection.
  • the polyurethane gels are materials with excellent shock-absorbing properties. In addition, they provide vibration insulation. Polyurethane gels are widely applied in the production of seats, backrests and ergonomic elements. For example, an important area of use for these gels is in the automotive sector.
  • the polyurethane gels are formed by the polymerisation reaction between an isocyanate and a polyol.
  • the polymerisation takes place in the presence of catalysts to increase the reaction speed.
  • plasticisers typically inert non-volatile liquids, can also be used to guarantee characteristic properties.
  • the use of plasticisers is being phased out as they have a tendency to separate and migrate to the gel surface. If separation and migration are substantial, the polyurethane gel progressively loses its characteristic properties.
  • the polyurethane gels are generally produced by moulding.
  • the moulding can be carried out by low-pressure casting or high-pressure injection into a mould. In this way, objects and padding can be obtained ready for use, without the need for further cutting or shaping processes.
  • some objects do not provide the desired level of comfort and have a high weight.
  • the technical task at the basis of the present invention is to devise a process for making a polyurethane gel capable of substantially obviating at least part of the aforementioned drawbacks.
  • a further important scope of the invention is to make a polyurethane gel capable of high cushioning and high thermal insulation.
  • a further important scope of the invention is to make a lighter polyurethane gel.
  • the measurements, values, shapes and geometric references (such as perpendicularity and parallelism), when associated with words like “about” or other similar terms such as “approximately” or “substantially”, are to be considered as except for measurement errors or inaccuracies due to production and/or manufacturing errors, and, above all, except for a slight divergence from the value, measurements, shape, or geometric reference with which it is associated.
  • these terms if associated with a value, preferably indicate a divergence of not more than 10% of the value.
  • treatment refers to the action and/or processes of a computer or similar electronic calculation device that manipulates and/or transforms data represented as physical, such as electronic quantities of registers of a computer system and/or memories in, other data similarly represented as physical quantities within computer systems, registers or other storage, transmission or information displaying devices.
  • the polyurethane gel according to the invention is globally referred to as 1.
  • a polyurethane gel is obtained by the reaction of at least one polyol with isocyanate.
  • the polyol has generally, preferably, average functionality less than or equal to three.
  • the isocyanate is generally a poly-isocyanate preferably having average functionality greater than or equal to two.
  • the polyurethane gel 1 is produced by a manufacturing process preferably comprising substantially a formulation step, a mixing and polymerization step and an expansion step.
  • gels are defined as a substantially diluted cross-linked system, which shows no flow when in the steady state, although the liquid phase may still diffuse through this system.
  • a gel has been defined phenomenologically as a soft, solid or solid-like material consisting of two or more components, one of which is a liquid, present in substantial quantities.
  • the formulation step includes the selection and dosage of at least one polyol 2 and isocyanate 3.
  • the polyol 2 preferably, as mentioned, has average functionality less than or equal to three.
  • the polyol 2 is a poly-propylene glycol and/or polyethylene glycol and/or a polyether polyol or polyester with greater than equal to two functionality (preferably two or three) and/or a polyether monol or a mixture thereof.
  • a particular embodiment involves the combined use of two or more polyols.
  • Such one or more polyols define a polyol blend 20.
  • the polyol blend 20 is preferably present in a weight percentage of between 85% and 90% of the total obtained from the formulation step.
  • the isocyanate 3 may be aliphatic or aromatic. For example, it may be based on diphenylmethane-4,4'- diisocyanate.
  • the isocyanate 3 is present in a weight percentage of between 6% and 10% of the total obtained from the formulation step.
  • no water is added and no water is present.
  • silicone surfactants are also not added in the formulation step, and more preferably also in the subsequent steps, and preferably no surfactants are present at all.
  • the formulation step comprises the selection and dosage of a catalyst 5.
  • the catalyst 5 is suitable to control the polymerisation reaction and thus allows obtaining a product having desired physical-mechanical characteristics.
  • This catalyst 5 may be amine or metallic.
  • the catalyst 5 is preferably present in a weight percentage of between 0% and 0.5% of the total obtained from the formulation step.
  • molecular sieves 6 are preferably chosen and dosed. They are preferably aluminosilicates, more preferably zeolites. The molecular sieves preferably have pores with a diameter between 3 A and 4 A. The molecular sieves 6 are preferably present in a weight percentage of between 1 % and 2% of the total obtained from the formulation step. They are suitable for absorbing traces of water present in the reactant mixture. This absorption is necessary for the finished product to have optimal characteristics.
  • the polymerization occurs consequently and substantially simultaneously with the mixing between polyol blend 20, to which catalyst 5 and molecular sieves 6 are preferably previously added, and isocyanate 3. It preferably takes place at a temperature between 15°C and 80°C.
  • the polymerisation temperature and the amount of catalyst 5 introduced in the first step determine the speed of the polymerisation reaction.
  • the expansion step increases the volume of the material, compared to the volume the material would have without the expansion step, by at least 10%, more preferably at least 50%, more preferably at least 100%, more preferably at least 20%, more preferably still at least 400%.
  • the expansion step can be achieved by two different methods. Each of the two methods makes it possible to obtain the polyurethane gel 1 with the desired characteristics.
  • the first approach involves introducing and saturating gas in the polyol blend 20, preferably comprising the catalyst 5 and molecular sieves 6, prior to the mixing and polymerisation step with the isocyanate 3.
  • the gas used is preferably air or carbon dioxide or blowing agents belonging to the families of products known as HFCs and/or HFOs having a boiling temperature in the range -40°C- + 40°C and or low-boiling liquids such as methyl formate or other similar products.
  • the polyol blend 20 is emulsified and after polymerization the polyurethane gel 1 has a finely microcellular structure.
  • the second approach comprises introducing expandable microspheres 4 into the polyol blend 20.
  • expandable microspheres 4 are capable of expanding when heated. They are therefore heated, together with the other components, preferably during the polymerisation reaction, then in the mixing and polymerisation phase.
  • expandable microspheres 4 are produced by the company Nouryon® and marketed under the brand name "Expancel”.
  • Such expandable microspheres 4 substantially comprise a thermoplastic polymeric outer shell 4a suitable for containing an inner fluid 4b. During expansion, the outer shell 4a progressively thins.
  • the inner fluid 4b is preferably a gas at room temperature. It is capable of expanding with increasing temperature.
  • the inner fluid 4b is preferably a hydrocarbon. More preferably it is methane, ethane, isobutane, neopentane or other similar.
  • the fluid 4b may be made by a mixing of the aforementioned substances.
  • said fluid 4b has a boiling temperature preferably between -20 °C and 100°C, more preferably between -20 °C and 50°C.
  • the outer shell 4a is preferably made from unsaturated monomers. Such monomers preferably include: acrylonitrile, methacrylonitrile, acrylic acid esters, methacrylic acid esters, and others.
  • the shell 4a can be made by a combination of the aforementioned monomers.
  • Similar microspheres are described in patent application WO 2007/091960 A1 , in particular between pages 12 and 16, or also in patent application WO 2019/101749 A1 , in which an alternative embodiment of outer shell 4a is presented.
  • the initial diameter of the expandable microspheres 4 is preferably between 10 pm and 16 pm. During expansion, such microspheres 4 can expand to a volume of four times their initial volume. Furthermore, such expansion is advantageously irreversible.
  • the expandable microspheres 4 preferably begin to expand at an operating temperature of between 80°C and 95°C. Furthermore, the expandable microspheres 4 preferably have a maximum expansion temperature of between 120°C and 135°C. Such microspheres are therefore suitable to be exposed to a temperature range between 80°C and 135°C for a time interval preferably between 1 s and 100 s, more preferably between 5 s and 60 s.
  • the microspheres 4 are added to the mixture subjected to polymerisation in a weight percentage of between 0.2% and 10% of the total.
  • the physical-mechanical characteristics of the polyurethane gel 1 are determined by the amount and timing of expansion of the expandable microspheres 4 during the polymerisation phase.
  • the polyurethane gel 1 preferably has a density between 1100 g/l and 250 g/l, and more preferably between 1100 g/l and 400 g/l, more preferably still between 1100 g/l and 600 g/l. Furthermore, it may be made with thickness having dimensions preferably between 0.1 mm and 200 mm.
  • the polyurethane gel 1 has numerous applications: in the automotive sector for the manufacture of seats or similar products dedicated to the automotive interior, in the textile sector in particular for sportswear, in the medical sector and even more.
  • the invention comprises a new process for making a polyurethane gel 1 . This process comprises an expansion step which can be carried out with two distinct approaches as previously described.
  • thermosetting polyurethane gel it makes it possible to obtain an expanded thermosetting polyurethane gel. Furthermore, such a polyurethane gel 1 increases the comfort of the objects in which it is used.
  • the polyurethane gel 1 has enhanced thermal insulation characteristics. Finally, polyurethane gel 1 has a reduced specific weight.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Polyurethanes Or Polyureas (AREA)

Abstract

It is provided a process for making a polyurethane gel (1), comprising: a first formulation step in which the choice and dosage of at least one polyol occurs (2) defining a polyol blend (20) and isocyanate (3), one Next phase of mixing and polymerization in which the polyol blend (20) and the isocyanate (3) react and a thermosetting polyurethane gel (1) is made, a phase of expansion during polymerization.

Description

DESCRIPTION
PROCESS FOR MAKING A POLYURETHANE GEL
The present invention relates to a process for making a polyurethane gel of the type specified in the preamble of the first claim. A gel is traditionally defined as a three-dimensional solid molecular network composed substantially of cross-linked polymers distributed in a gelatinous matrix of any shape or size and which does not exhibit steady-state flow. The term "gel" is used here to describe a soft polyurethane with a gel-like consistency. The polyurethane gel is comfortable to the touch and is capable of slowly returning to its original shape after deformation. In general, it is a solid and compact material. Such gels can be covered with a thin layer of elastomeric material to provide surface protection.
The polyurethane gels are materials with excellent shock-absorbing properties. In addition, they provide vibration insulation. Polyurethane gels are widely applied in the production of seats, backrests and ergonomic elements. For example, an important area of use for these gels is in the automotive sector.
The polyurethane gels are formed by the polymerisation reaction between an isocyanate and a polyol. The polymerisation takes place in the presence of catalysts to increase the reaction speed. In order to obtain such gels, plasticisers, typically inert non-volatile liquids, can also be used to guarantee characteristic properties. The use of plasticisers is being phased out as they have a tendency to separate and migrate to the gel surface. If separation and migration are substantial, the polyurethane gel progressively loses its characteristic properties.
The polyurethane gels are generally produced by moulding. The moulding can be carried out by low-pressure casting or high-pressure injection into a mould. In this way, objects and padding can be obtained ready for use, without the need for further cutting or shaping processes.
The known technique described includes some important drawbacks.
In particular, some objects do not provide the desired level of comfort and have a high weight. In addition, one would like to achieve better thermal insulation and even greater cushioning of the known polyurethane gels and also a reduction in the weight of the objects.
In this situation, the technical task at the basis of the present invention is to devise a process for making a polyurethane gel capable of substantially obviating at least part of the aforementioned drawbacks.
In the context of said technical task, it is an important aim of the invention to obtain a highly comfortable polyurethane gel.
A further important scope of the invention is to make a polyurethane gel capable of high cushioning and high thermal insulation. A further important scope of the invention is to make a lighter polyurethane gel.
The specified technical task and purposes are achieved by a process for making a polyurethane gel as claimed in the appended claim 1 .
Preferred technical solutions are disclosed in the dependent claims.
The features and advantages of the invention are hereinafter clarified by the detailed description of preferred embodiments of the invention, with reference to the annexed figures, wherein: the Fig. 1 schematises the procedure according to the invention.
In the present document, the measurements, values, shapes and geometric references (such as perpendicularity and parallelism), when associated with words like “about” or other similar terms such as “approximately” or “substantially”, are to be considered as except for measurement errors or inaccuracies due to production and/or manufacturing errors, and, above all, except for a slight divergence from the value, measurements, shape, or geometric reference with which it is associated. For instance, these terms, if associated with a value, preferably indicate a divergence of not more than 10% of the value.
Moreover, when used, terms such as “first”, “second”, “higher”, “lower”, “main” and “secondary” do not necessarily identify an order, a priority of relationship or a relative position, but can simply be used to clearly distinguish between their different components.
Unless otherwise specified, as results in the following discussions, terms such as “treatment”, “computing”, “determination”, “calculation”, or similar, refer to the action and/or processes of a computer or similar electronic calculation device that manipulates and/or transforms data represented as physical, such as electronic quantities of registers of a computer system and/or memories in, other data similarly represented as physical quantities within computer systems, registers or other storage, transmission or information displaying devices.
The measurements and data reported in this text are to be considered, unless otherwise indicated, as performed in the International Standard Atmosphere ICAO (ISO 2533:1975).
With reference to the Figures, the polyurethane gel according to the invention is globally referred to as 1.
A polyurethane gel is obtained by the reaction of at least one polyol with isocyanate. In particular, the polyol has generally, preferably, average functionality less than or equal to three. The isocyanate is generally a poly-isocyanate preferably having average functionality greater than or equal to two. The polyurethane gel 1 is produced by a manufacturing process preferably comprising substantially a formulation step, a mixing and polymerization step and an expansion step.
As is known, gels are defined as a substantially diluted cross-linked system, which shows no flow when in the steady state, although the liquid phase may still diffuse through this system. A gel has been defined phenomenologically as a soft, solid or solid-like material consisting of two or more components, one of which is a liquid, present in substantial quantities.
By weight, gels are mostly liquids, yet they behave like solids due to a three- dimensional cross-linked network within the liquid. The formulation step includes the selection and dosage of at least one polyol 2 and isocyanate 3.
The polyol 2, preferably, as mentioned, has average functionality less than or equal to three. Preferably, the polyol 2 is a poly-propylene glycol and/or polyethylene glycol and/or a polyether polyol or polyester with greater than equal to two functionality (preferably two or three) and/or a polyether monol or a mixture thereof. A particular embodiment involves the combined use of two or more polyols. Such one or more polyols define a polyol blend 20. The polyol blend 20 is preferably present in a weight percentage of between 85% and 90% of the total obtained from the formulation step. The isocyanate 3 may be aliphatic or aromatic. For example, it may be based on diphenylmethane-4,4'- diisocyanate. Preferably, the isocyanate 3 is present in a weight percentage of between 6% and 10% of the total obtained from the formulation step. Preferably, in the formulation step, and more preferably also in the subsequent steps, no water is added and no water is present.
Preferably, silicone surfactants are also not added in the formulation step, and more preferably also in the subsequent steps, and preferably no surfactants are present at all.
In addition, the formulation step comprises the selection and dosage of a catalyst 5. The catalyst 5 is suitable to control the polymerisation reaction and thus allows obtaining a product having desired physical-mechanical characteristics. This catalyst 5 may be amine or metallic. The catalyst 5 is preferably present in a weight percentage of between 0% and 0.5% of the total obtained from the formulation step.
In said formulation step, molecular sieves 6 are preferably chosen and dosed. They are preferably aluminosilicates, more preferably zeolites. The molecular sieves preferably have pores with a diameter between 3 A and 4 A. The molecular sieves 6 are preferably present in a weight percentage of between 1 % and 2% of the total obtained from the formulation step. They are suitable for absorbing traces of water present in the reactant mixture. This absorption is necessary for the finished product to have optimal characteristics.
The polymerization, occurs consequently and substantially simultaneously with the mixing between polyol blend 20, to which catalyst 5 and molecular sieves 6 are preferably previously added, and isocyanate 3. It preferably takes place at a temperature between 15°C and 80°C.
The polymerisation temperature and the amount of catalyst 5 introduced in the first step determine the speed of the polymerisation reaction. Preferably, the expansion step increases the volume of the material, compared to the volume the material would have without the expansion step, by at least 10%, more preferably at least 50%, more preferably at least 100%, more preferably at least 20%, more preferably still at least 400%.
The expansion step can be achieved by two different methods. Each of the two methods makes it possible to obtain the polyurethane gel 1 with the desired characteristics.
The first approach involves introducing and saturating gas in the polyol blend 20, preferably comprising the catalyst 5 and molecular sieves 6, prior to the mixing and polymerisation step with the isocyanate 3. The gas used is preferably air or carbon dioxide or blowing agents belonging to the families of products known as HFCs and/or HFOs having a boiling temperature in the range -40°C- + 40°C and or low-boiling liquids such as methyl formate or other similar products. In this approach, during the mixing and polymerization step, the polyol blend 20 is emulsified and after polymerization the polyurethane gel 1 has a finely microcellular structure. The second approach comprises introducing expandable microspheres 4 into the polyol blend 20. These expandable microspheres 4 are capable of expanding when heated. They are therefore heated, together with the other components, preferably during the polymerisation reaction, then in the mixing and polymerisation phase. For example, expandable microspheres 4 are produced by the company Nouryon® and marketed under the brand name "Expancel". Such expandable microspheres 4 substantially comprise a thermoplastic polymeric outer shell 4a suitable for containing an inner fluid 4b. During expansion, the outer shell 4a progressively thins. The inner fluid 4b is preferably a gas at room temperature. It is capable of expanding with increasing temperature. The inner fluid 4b is preferably a hydrocarbon. More preferably it is methane, ethane, isobutane, neopentane or other similar. Furthermore, the fluid 4b may be made by a mixing of the aforementioned substances. In particular, said fluid 4b has a boiling temperature preferably between -20 °C and 100°C, more preferably between -20 °C and 50°C. The outer shell 4a is preferably made from unsaturated monomers. Such monomers preferably include: acrylonitrile, methacrylonitrile, acrylic acid esters, methacrylic acid esters, and others. In particular, the shell 4a can be made by a combination of the aforementioned monomers. Similar microspheres are described in patent application WO 2007/091960 A1 , in particular between pages 12 and 16, or also in patent application WO 2019/101749 A1 , in which an alternative embodiment of outer shell 4a is presented. The initial diameter of the expandable microspheres 4 is preferably between 10 pm and 16 pm. During expansion, such microspheres 4 can expand to a volume of four times their initial volume. Furthermore, such expansion is advantageously irreversible.
The expandable microspheres 4 preferably begin to expand at an operating temperature of between 80°C and 95°C. Furthermore, the expandable microspheres 4 preferably have a maximum expansion temperature of between 120°C and 135°C. Such microspheres are therefore suitable to be exposed to a temperature range between 80°C and 135°C for a time interval preferably between 1 s and 100 s, more preferably between 5 s and 60 s.
Depending on the desired product characteristics, the microspheres 4 are added to the mixture subjected to polymerisation in a weight percentage of between 0.2% and 10% of the total. The physical-mechanical characteristics of the polyurethane gel 1 are determined by the amount and timing of expansion of the expandable microspheres 4 during the polymerisation phase.
In particular, the polyurethane gel 1 preferably has a density between 1100 g/l and 250 g/l, and more preferably between 1100 g/l and 400 g/l, more preferably still between 1100 g/l and 600 g/l. Furthermore, it may be made with thickness having dimensions preferably between 0.1 mm and 200 mm.
The polyurethane gel 1 has numerous applications: in the automotive sector for the manufacture of seats or similar products dedicated to the automotive interior, in the textile sector in particular for sportswear, in the medical sector and even more. The invention comprises a new process for making a polyurethane gel 1 . This process comprises an expansion step which can be carried out with two distinct approaches as previously described.
The process for making a polyurethane gel 1 according to the invention achieves important advantages.
In fact, it makes it possible to obtain an expanded thermosetting polyurethane gel. Furthermore, such a polyurethane gel 1 increases the comfort of the objects in which it is used.
The polyurethane gel 1 has enhanced thermal insulation characteristics. Finally, polyurethane gel 1 has a reduced specific weight.

Claims

1. Procedure for making a polyurethane gel (1), comprising:
- a first formulation step in which the choice and dosage of:
- at least one polyol (2), defining a polyol blend (20),
- isocyanate (3),
- a subsequent mixing and polymerisation step in which said polyol blend (20) and said isocyanate (3) react and a thermosetting polyurethane gel (1) is produced, and characterised by that comprising an expansion phase during said polymerisation.
2. Process according to claim 1 , wherein no water is added in said formulation step and in said mixing and polymerization step.
3. Process according to any one of the preceding claims, wherein no silicone surfactant is added in said formulation step and in said mixing and polymerization step.
4. Process according to any one of the preceding claims, wherein in said formulation step and in said mixing and polymerization step no surfactants are added.
5. Process according to any one of the preceding claims, wherein said expansion step is performed by introducing and saturating gas in said polyol blend (20) prior to said mixing and polymerization step.
6. A process according to any one of claims 1 to 4, wherein said expanding step occurs by introducing expandable microspheres (4) into said polyol blend (20) and said expandable microspheres (4) being capable of expanding during said polymerization reaction.
7. Procedure according to the preceding claim, wherein said expandable microspheres (4) begin to expand at an operating temperature of between 80°C and 95°C.
8. Procedure according to any one of claims 6 - 7, wherein said expandable microspheres (4) are exposed to a temperature range between 80°C and 135°C for a time interval between 5 s and 60 s.
9. A process according to any one of claims 6 - 8, wherein said expandable microspheres (4) have initial diameter sizes between 10 pm and 16 pm.
10. Procedure according to any one of claims 6 - 9, wherein said expandable microspheres (4) have maximum expansion temperature between 120°C and 135°C.
11. Polyurethane gel (1) made by a process according to any one of the preceding claims, wherein said expansion step, preferably, increases the volume of said polyurethane gel (1), compared to the volume the same would have without said expansion step, by at least 10%.
12. Polyurethane gel (1) according to the preceding claim, having a density between 1100 g/l and 250 g/l.
13. Polyurethane gel (1) according to the preceding claim, having a density between 1100 g/l and 400 g/l.
14. Polyurethane gel (1) according to the preceding claim, having a density between 1100 g/l and 600 g/l.
15. Polyurethane gel (1 ) according to any one of claims 8-9, having a thickness of between 0.1 mm and 200 mm.
EP22714242.9A 2021-03-15 2022-03-07 Process for making a polyurethane gel Pending EP4308620A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT202100006140 2021-03-15
PCT/IB2022/051989 WO2022195398A1 (en) 2021-03-15 2022-03-07 Process for making a polyurethane gel

Publications (1)

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EP4308620A1 true EP4308620A1 (en) 2024-01-24

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WO (1) WO2022195398A1 (en)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6458861B1 (en) * 2001-01-18 2002-10-01 Bayer Antwerp N.V. Carbon dioxide blown low density, flexible microcellular elastomers suitable for preparing shoe components
DE102004010809A1 (en) * 2004-03-05 2005-09-22 Bayer Materialscience Ag Flexible moldings made of foamed polyurethane and their use
WO2006027805A1 (en) * 2004-09-08 2006-03-16 Elachem S.R.L. Composition and process for the realization of low density expanded products
US10113043B2 (en) * 2010-02-26 2018-10-30 Twin Brook Capital Partners, Llc Polyurethane gel particles, methods and use in flexible foams

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