WO2022266787A1

WO2022266787A1 - Polyurethane products and processes for preparing the same

Info

Publication number: WO2022266787A1
Application number: PCT/CN2021/101153
Authority: WO
Inventors: Tao Wang; Yanbin FAN; Hongyu Chen; Kang Chen; Xiaolin Huang
Original assignee: Dow Global Technologies Llc
Priority date: 2021-06-21
Filing date: 2021-06-21
Publication date: 2022-12-29
Also published as: CN117413000A

Abstract

Disclosed is a process for preparing a polyurethane product, comprising: providing an isocyanate component (i), and an isocyanate-reactive component (ii) comprising at least one unsaturated linear diol represented by Formula (I), at least one polyol other than the unsaturated linear diol, and at least one free radical initiator having a decomposition temperature above 120°C; and subjecting the above stated components to a multi-stage thermal treatment. The polyurethane product thus prepared can exhibit superior mechanical strengths even at an elevated temperature, decreased internal heat buildup, improved heat resistance, and desirable manufacture cost. A polyurethane product prepared by the process and a composition for preparing the polyurethane product are also provided. HO-R₁-C (R₂) =C (R₃) -R₄-OH Formula (I)

Description

POLYURETHANE PRODUCTS AND PROCESSES FOR PREPARING THE SAME

FIELD OF THE INVENTION

The present disclosure relates to a polyurethane product, such as a microcellular polyurethane foam or a solid tire, and a process for preparing the same. The process comprises the steps of two-stage curing, micro-phase separation and crosslinking of ethylenically unsaturated residual group in the polyurethane backbone with the assistance of a free radical initiator having higher decomposition temperature. The polyurethane product exhibits excellent properties such as inhibited internal heat buildup, enhanced thermal resistance, tear strength and cost effectiveness, among others.

BACKGROUND TECHNOLOGY

Microcellular polyurethane foams are foamed polyurethane materials with a density of about 100-900 kg/m ³ and are usually fabricated via a two-component process of reacting Component A (polyols, chain extenders, foaming agents, catalysts, surfactants, etc. ) and Component B (monomeric isocyanate, prepolymer of polyols and isocyanates, or blend thereof) . The two components are usually blended at high speed and then transferred into varied molds with desired shapes. Over the past decades, microcellular polyurethane foams have been employed in a wide range of end use applications like shoemaking (e.g., soles) and automotive industries (e.g., bumpers and arm rests of integral skin foams) . Recently, microcellular polyurethane foams have been explored in solid tire applications. These microcellular polyurethane solid tires have been attractive due to the possibility of eliminating deflation risk that all the pneumatic rubber tires inherently possess and may bring about potential safety issues and increased maintenance costs.

However, due to the poor heat resistance and high “internal heat” build-up of PU, the solid tire has been limited to the low speed applications. The internal heat buildup originates from transition of mechanical energy into heat inside polyurethanes and is characterized by significant augmentation of the tire temperature during rolling especially under high speed and load. With increasing temperature, material failures including fatigue cracking and/or melting are usually observed. Thus, the upper limits of speed and load under which a polyurethane tire can operate are determined by internal heat buildup, and of course, thermal stability of the polyurethane tire. Generally, the dominate market requests >40km/hour speed which is much higher than the upper limit of the speed due to the dramatic and quick drop of the modulus at a high temperature of e.g. around 120℃.

Significant efforts have been made to increase the thermal stability of polyurethanes and reduce the “internal heat buildup” in the polyurethane product by introduction of functional moieties e.g. isocyanurate, oxazolidone, oxamide or borate groups or to reduce the “internal heat buildup” in polyurethanes by using special isocyanates like 1, 5-naphthylene diisocyanate. However, the above indicated modification by using the chemicals with special groups or special isocyanates are usually too expensive to be commercialized. Besides, it was found that when compared with polyether polyols, polyester polyols can impart polyurethanes with higher tear strength due to higher cohesive energy thereof, but their processing and durability are poor due to their high viscosity and insufficient resistance to hydrolytic attack, respectively. There were also reports about using specific isocyanates like 1, 5-Naphthalene diisocyanate (NDI) and specific chain extender (e.g. amines) to improve the tear strength and thermal stability of polyurethane material, but all of raw materials exhibit unacceptable disadvantages such as excessively high cost, poor storage stability, poor processing properties, etc.

For the above reasons, there is still a need in the polyurethane manufacture industry to develop a cost-effective technology for preparing a polyurethane, such as a microcellular polyurethane foam or a solid tire, which can achieve improved heat resistance, enhanced mechanical properties and reduced internal heat buildup even at elevated temperature. After persistent exploration, the inventors have surprisingly developed such a technology which can achieve one or more of the above targets.

SUMMARY OF THE INVENTION

The present disclosure provides a technical solution comprising the combination of a specific formulation and a unique multi-stage process.

In a first aspect of the present disclosure, the present disclosure provides a process for preparing a polyurethane product, comprising:

(A) providing an isocyanate component (i) comprising at least one first isocyanate compound having at least two isocyanate groups, and an isocyanate-reactive component (ii) comprising at least one unsaturated linear diol represented by Formula I,

HO-R ₁-C (R ₂) =C (R ₃) -R ₄-OH Formula I

wherein each of R ₁ and R ₄ is independently selected from the group consisting of covalent bond, C ₁ to C ₆ alkylene group, C ₂-C ₆ alkenylene group, C ₆-C ₁₂ cycloalkylene group, and C ₆-C ₁₂ arylene group, and each of R ₂ and R ₃ is independently selected from the group consisting of hydrogen and C ₁-C ₆ alkyl group,

at least one polyol other than the unsaturated linear diol, and

at least one free radical initiator having a decomposition temperature above 120℃;

(B) combining the isocyanate component (i) with the isocyanate-reactive component (ii) to form a mixture; and

(C) subjecting the mixture to a multi-stage thermal treatment comprising

a low temperature treatment stage in which the curing and the microphase-separation are achieved without incurring the activation of the free radical initiator, and

a high temperature treatment stage in which the free radical initiator is activated to initiate the crosslinking of carbon-carbon double bond derived from the unsaturated linear diol represented by Formula I.

According to an embodiment of the present disclosure, the low temperature treatment stage comprises: (C1) curing the mixture at a first curing temperature of 20 ℃ to 60 ℃ to produce a pre-cured substance; (C2) curing the pre-cured substance at a second curing temperature of 0 ℃ to 50 ℃ to produce a cured substance; and (C3) heating the cured substance at a first heating temperature of 30 ℃ to 80 ℃ to form a microphase-separated substance; and

the high temperature treatment stage comprises (C4) heating the microphase-separated substance at a second heating temperature of 90 ℃ to 140 ℃ to produce the polyurethane product.

In a second aspect of the present disclosure, the present disclosure provides a polyurethane product obtained by the process of the first aspect, wherein the polyurethane product can be a tire of various apparatuses such as e-bike, bicycle, motorcycle, automobile, cart, wheelchair and aircraft, and is preferably the tire of an e-bike.

In a third aspect of the present disclosure, a composition for preparing the polyurethane product of the present disclosure is provided, wherein the composition comprises the isocyanate component (i) and the isocyanate-reactive component (ii) as disclosed in the first aspect.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DETAILED DESCRIPTION OF THE INVENTION

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Also, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference.

As disclosed herein, “and/or” means “and, or as an alternative” . All ranges include endpoints unless otherwise indicated. Unless indicated otherwise, all the percentages and ratios are calculated based on weight, and all the molecular weights are weight average molecular weights.

In the present disclosure, it is found that the use of a specific formulation, preferably in combination with a particularly designed multistage curing/microphase-separation /crosslinking process, enables a significant improvement of the modulus of the resultant microcellular PU foam at elevated temperature, thus rendering the microcellular PU foam suitable for high speed applications.

According to various embodiments of the present disclosure, the polyurethane product is prepared by using a “two-component” , “two-part” or “two-package” composition comprising an isocyanate component (i) and an isocyanate-reactive component (ii) . The isocyanate component (i) and the isocyanate-reactive component (ii) are transported and stored separately, combined shortly or immediately before being used during the manufacture of the polyurethane product. Once combined, the isocyanate groups in component (i) reacts with the isocyanate-reactive groups (particularly, hydroxyl group) in component (ii) in two curing stages to form polyurethane.

According to an embodiment of the present disclosure, the isocyanate component (i) and the isocyanate-reactive component (ii) are combined in a mold, such as a mold having an internal space shape and size corresponding to that of the target product, e.g. a solid tire.

According to an embodiment of the present disclosure, once the isocyanate component (i) is combined with the isocyanate-reactive component (ii) , the resultant mixture of the two components (i) and (ii) is subject to multi-stage thermal treatment comprising a low temperature treatment stage and a high temperature treatment stage, wherein the high temperature treatment stage is conducted at a temperature higher than that of the low temperature treatment stage. The low temperature treatment stage may comprise at least one temperature or a temperature plot under which the mixture is cured, i.e. the isocyanate groups substantially react with the isocyanate-reactive groups, and the microphases within the polyurethane are separated, e.g. the hard segment microphase (such as the polymeric segment derived from the isocyanate compound) and the soft segment microphase (such as the polymeric segment derived from the polyol) in the polyurethane are separated from each other. Nevertheless, the temperature/temperature plot of the low temperature treatment stage will not incur the activation of the free radical initiator, thus the crosslinking of carbon-carbon double bond will not substantially occur in this low temperature treatment stage. The high temperature treatment stage comprises at least one temperature or a temperature plot under which the free radical initiator is activated to initiate the crosslinking of carbon-carbon double bond derived from the unsaturated linear diol represented by Formula I.

According to an embodiment of the present disclosure, the low temperature treatment stage comprises the following steps: (a) a first curing step at a first curing temperature, (b) a second curing step at a second curing temperature, (c) a microphase-separation step at a first heating temperature and the high temperature treatment stage comprises (d) a crosslinking step at a second heating temperature. Without being limited to any specific theory, one of the technical breakthroughs of the present application resides in the combination of the particularly selected unsaturated linear diol and the free radical initiator having a high decomposition temperature. Besides, it is also found that the performance properties of the polyurethane product can be further improved by the particularly designed “two stage curing-microphase separation-crosslinking” preparation procedures.

According to an embodiment of the present disclosure, once the isocyanate component (i) is combined with the isocyanate-reactive component (ii) , the resultant mixture of the two components (i) and (ii) is subject to the following steps: (a) a first curing step at a first curing temperature, (b) a second curing step at a second curing temperature, (c) a microphase- separation step at a first heating temperature and (d) a crosslinking step at a second heating temperature. Without being limited to any specific theory, one of the technical breakthroughs of the present application resides in the combination of the particularly selected unsaturated linear diol and the free radical initiator having a high decomposition temperature. Besides, it is also found that the performance properties of the polyurethane product can be further improved by the particularly designed “two stage curing-microphase separation-crosslinking” preparation procedures.

According to one embodiment of the present disclosure, the first curing temperature can be in the range of 20℃ to 60℃, such as from 25 ℃ to 60 ℃, or from 30 ℃ to 60 ℃, or from 35 ℃ to 60 ℃, or from 40 ℃ to 60 ℃, or from 45 ℃ to 60 ℃, or from 40 ℃ to 55 ℃, or from 40 ℃ to 50 ℃. According to another embodiment of the present disclosure, the duration of the first curing step is from 3 to 40 minutes, or from 4 to 35 minutes, or from 5 to 30 minutes, or from 6 to 25 minutes, or from 7 to 20 minutes. Without being limited to any specific theory, the NCO group in the isocyanate component (i) partially reacts with the hydroxyl group and, optionally other isocyanate-reactive groups (such as amino group, thiol group, etc. if any) in the isocyanate-reactive component (ii) during the first curing step to form a partially cured or pre-cured substance which can be in the form of a microcellular foam. According to an embodiment of the present disclosure, the first curing steps is conducted in the same mold, such as a mold having an internal space shape and size corresponding to that of the target product, e.g. a solid tire.

According to one embodiment of the present disclosure, the pre-cured substance is cooled or allowed to cool to ambient temperature of e.g. about from 15 ℃ to 35 ℃, or from 20 ℃ to 30 ℃, and is then subject to the second curing step. According to another embodiment of the present disclosure, the pre-cured substance is removed from the mold (i.e. demolded) before the second curing step.

According to one embodiment of the present disclosure, the second curing temperature can be in the range of 0℃ to 50℃, such as from 5 ℃ to 45 ℃, or from 10 ℃ to 40 ℃, or from 15 ℃ to 35 ℃, or from 20 ℃ to 30 ℃. According to another embodiment of the present disclosure, the second curing temperature is ambient temperature. According to another embodiment of the present disclosure, the duration of the second curing step is from 10 to 48 hours, or from 11 to 40 hours, or from 12 to 30 hours, or from 14 to 24 hours, or from 16 to 20 hours. According to another embodiment of the present disclosure, the second curing step lasts overnight. Without being limited to any specific theory, the unreacted NCO group and isocyanate-reactive groups remained in the pre-cured substance react with one another during the second curing step to form a cured or fully-cured substance.

According to one embodiment of the present disclosure, the first heating temperature can be in the range of 30℃ to 80℃, such as from 35 ℃ to 75 ℃, or from 40 ℃ to 70 ℃, or from 45 ℃ to 65 ℃, or from 50 ℃ to 60 ℃, or from 45 ℃ to 55 ℃. According to another embodiment of the present disclosure, the first heating temperature is identical with the first curing temperature. According to another embodiment of the present disclosure, the duration of the microphase-separation step is from 10 to 48 hours, or from 12 to 40 hours, or from 16 to 35 hours, or from 20 to 30 hours. Without being limited to any specific theory, the hard segment microphase (such as the polymeric segment derived from the isocyanate compound) and the soft segment microphase (such as the polymeric segment derived from the polyol) in the polyurethane are gradually separated from each other and thus suitable microphase hard/soft segment separation occurs during the microphase-separation step. As used herein, the expression of “microphase separation” refers to the displacement and/or rearrangement of polyurethane main-chain under the first heating temperature which will result in the approaching, gathering and accumulation of identical microphases (i.e. all the hard segment microphases being displaced to locations closer to other hard segment microphases, and all the soft segment microphases being displaced to locations closer to other soft segment microphases, as compared with the state in the fully-cured substance prior to the microphase separation step) .

According to one embodiment of the present disclosure, the second heating temperature can be in the range of 90 ℃ to 140 ℃, such as from 95 ℃ to 135 ℃, or from 100 ℃ to 130 ℃, or from 105 ℃ to 125 ℃, or from 110 ℃ to 120 ℃. According to another embodiment of the present disclosure, the duration of the crosslinking step is from 0.5 to 24 hours, or from 0.6 to 22 hours, or from 0.7 to 20 hours, or from 0.8 to 18 hours, or from 0.9 to 16 hours, or from 1.0 to 14 hours, or from 1.5 to 12 hours. Without being limited to any specific theory, the ethylenically unsaturated functionality of the unsaturated linear diol represented by Formula I is introduced into the polyurethane backbone during the above stated first and second curing steps, and is basically kept intact until the crosslinking step. In the crosslinking step, the initiator, which is added as a part of the isocyanate-reactive component, decomposes under the second heating temperature to produce free radicals which initiates the crosslinking of the ethylenically unsaturated functionality included in the polyurethane backbone.

According to one embodiment of the present disclosure, the polyurethane product comprises crosslinked structure derived from the unsaturated linear diol represented by Formula I. For example, the above stated crosslinked structure may be formed by the reaction between the carbon-carbon double bonds of residual groups derived from the unsaturated linear diol represented by Formula I contained in two polyurethane main chains, or the reaction of said carbon-carbon double bond with one or more reactive groups attached to another polyurethane main chain. According to one embodiment of the present disclosure, at least 10%, or at least 15 %, or at least 20 %, or at least 25 %, or at least 30 %, or at least 35 %, or at least 40 %, or at least 45 %, or at least 50 %, or at least 55 %, or at least 60 %, or at least 65 %, or at least 70 %, or at least 75 %, or at least 80 %, or at least 85 %, or at least 90 %, or at least 95 %, or at least 99 %, or 100 %of said carbon-carbon double bond, based on the total molar amount of the unsaturated linear diol represented by Formula I, have been crosslinked during this crosslinking step.

As stated above, one important technical breakthrough of the present application resides in the particularly designed composition, especially of the isocyanate-reactive component (ii) . According to various embodiments of the present disclosure, the isocyanate-reactive component (ii) comprises at least one unsaturated linear diol represented by Formula I,

HO-R ₁-C (R ₂) =C (R ₃) -R ₄-OH Formula I

at least one polyol other than the unsaturated linear diol,

at least one free radical initiator having a decomposition temperature above 120℃, and optionally one or more other additives or processing aids.

According to an embodiment of the present disclosure, the unsaturated linear diol represented by Formula I is used for incorporating residual moiety of linear unsaturated diols having carbon-carbon double bond (which is also known as “ethylenically unsaturated linear diol” or “linear diol having ethylenically unsaturated functionality” ) into the polyurethane backbones. Such ethylenically unsaturated residual moiety is basically retained intact during the two curing steps and the microphase separation step, and then crosslinking of the ethylenically unsaturated residual moiety occurs during the crosslinking step. For example, the unsaturated linear diol represented by Formula I can be selected from the group consisting of 2-butene-1, 4-diol, 2-pentene-1, 5-diol, 2-hexene-1, 6-diol, 3-hexene-1, 6-diol, 2, 4-hexadiene-1, 6-diol, 2-heptene-1, 7-diol, 3-heptene-1, 7-diol, 2, 4-heptadiene-1, 7-diol, 2, 5-heptadiene-1, 7-diol, 2-octene-1, 8-diol, 3-octene-1, 8-diol, 4-octene-1, 8-diol, 2, 4-octadiene-1, 8-diol, 2, 5-octadiene-1, 8-diol, 2, 6-octadiene-1, 8-diol, 1, 2-bis (4-hydroxylcyclohexyl) ethylene, 1, 2-bis (3-hydroxylcyclohexyl) ethylene, 1, 2-bis (4-methylolcyclohexyl) ethylene, 1, 2-bis (3-methylolcyclohexyl) ethylene, 1, 2-bis (4-hydroxyl-phenyl) ethylene, 1, 2-bis (4-methylol-phenyl) ethylene, 1, 2-bis (4-hydroxyl-benzyl) -ethylene, 1, 2-bis (4-methylol-benzyl) ethylene, and any combinations thereof. According to a specific embodiment, the unsaturated linear diol represented by Formula I is 2-butene-1, 4-diol, which is also known as butenediol (BEDO) in the context of the present disclosure. According to an embodiment of the present disclosure, the content of the above said unsaturated linear diol represented by Formula I is from 1%to 20 %by weight, based on the total weight of the isocyanate-reactive component (ii) , such as in the numerical range obtained by combining any two of the following end point values: 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6wtt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, 12.5 wt%, 13 wt%, 13.5 wt%, 14 wt%, 14.5 wt%, 15 wt%, 15.5 wt%, 16 wt%, 16.5 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, 19.5 wt%and 20 wt%.

According to an embodiment of the present disclosure, at least 70 mol%, or at least 75 mol%, or at least 80 mol%, or at least 85 mol%, or at least 90 mol%, or at least 95 mol%, or at least 98 mol%, or at least 99 mol%, or up to 100 mol%of the ethylenically unsaturated functionality derived from the unsaturated linear diol represented by Formula I, based on the total molar amount of the unsaturated linear diol represented by Formula I contained in the isocyanate-reactive component (ii) , is present in the polyurethane backbone of the polyurethane product. According to another embodiment of the present disclosure, the isocyanate-reactive component (ii) , more preferably all the raw materials for preparing the polyurethane product, do not comprise an unsaturated compound and/or a branched compound which will introduce an ethylenically unsaturated side chain into the polyurethane backbone formed by reacting the (ii) isocyanate-reactive component with the (i) isocyanate component, thus none of the polyurethane backbones in the polyurethane material comprises an ethylenically unsaturated side chain. In an embodiment of the present disclosure, the unsaturated linear diol represented by Formula I is the only one monomer which will introduce ethylenically unsaturated functionality (especially, carbon-carbon double bond) in the backbone of the resultant polyurethane product. In another embodiment of the present disclosure, the unsaturated linear diol represented by Formula I is the only one monomer which will introduce carbon-carbon double bond in the resultant polyurethane product.

According to an embodiment of the present disclosure, the free radical initiator has a decomposition temperature above 120 ℃, wherein the decomposition temperature is defined as the temperature where the half life t 1/2 of the initiator equals to 1 hour (i.e. T@t _1/2=1 hour) . Particularly, in the context of the present disclosure, the parameter “T@t _1/2=1 hour” refers to the specific temperature at which the content of the free radical initiator can be reduced by 50%in one hour. This parameter of a specific compound can be either determined by monitoring a diluted solution of the initiator in monochlorobenzene with Differential Scanning Calorimetry-Thermal Activity Monitor (DSC-TAM) , or by calculation with the Arrhenius equation based on the kinetic data obtained from notebook. According to a preferable embodiment of the present disclosure, the the free radical initiator has a decomposition temperature of above 120 ℃ and up to 200 ℃, or up to 190 ℃.

Exemplary free radical initiators having desirable decomposition temperature are listed in the following table 1:

Table 1: Exemplary free radical initiators having a decomposition temperature of above 120 ℃:

According to an embodiment of the present disclosure, the preferable initiators have the above stated decomposition temperature of higher than 120 ℃ and will not be substantially consumed during the two curing steps and the microphase separation step, but will decompose to produce free radicals when being heated at the second heating temperature in the crosslinking step. The free radicals produced by the initiator will initiate the crosslinking of the ethylenically unsaturated functionality (which is derived from the unsaturated linear diol represented by Formula I) within the polyurethane backbone. As evidenced by the following inventive examples and comparative examples, it was surprisingly found that the above stated “decomposition temperature” is an essential parameter for selecting useful free radical initiators, and many initiators, which appear to have molecular structures quite similar with that of the inventive initiators, cannot achieve desirable technical effect once they exhibit a “decomposition temperature” no higher than 120℃.

According to an embodiment of the present disclosure, the amount of the above stated initiator is from 0.5%to 10%, or from 0.5%to 8%, or from 0.5%to 6%, or from 0.5%to 5%, or from 0.8%to 5%, or from 1.0%to 5%, by weight based on the weight of the unsaturated linear diol represented by Formula I.

In the context of the present disclosure, the term “an unsaturated compound which will introduce an ethylenically unsaturated side chain into the polyurethane backbone” refers to a compound whose molecular chain containing one or more ethylenically unsaturated functionalities (carbon-carbon double bond) is not terminated at both ends with a isocyanate-reactive (such as hydroxyl group, amine group, carboxyl group, etc. ) , and thus the ethylenically unsaturated functionality will be linked to the polyurethane backbone in the form of a side chain rather than as part of the linear polyurethane backbone. For example, 3- (allyloxy) propane-1, 2-diol, whose molecular structure is shown in Formula II, is a typical unsaturated compound which “will form an ethylenically unsaturated side chain” attached to the polyurethane backbone, hence such a compound and any analogs shall be particularly excluded from the polyurethane composition of the present disclosure.

According to one embodiment of the present disclosure, the molar amount of the ethylenically unsaturated side chain is less than 30%, or less than 20%, or less than 15%, or less 10%, or less than 8%, or less than 5%, or less than 2%, or less than 1%, or less than 0.5%, based on the molar amount of the unsaturated linear diol represented by Formula I. According to another embodiment of the present disclosure, all the polyurethane backbones are linear and do not comprise any side chain at all.

According to an alternative embodiment of the present disclosure, the isocyanate-reactive component (ii) comprises at least one unsaturated linear diol represented by Formula I, at least one saturated linear C ₂-C ₁₂ aliphatic diol, and at least one additional polyol, wherein the at least one additional polyol is different from either one of the above diols and is selected from the group consisting of C ₂-C ₁₆ aliphatic polyhydric alcohols comprising at least two hydroxyl groups, C ₆-C ₁₅ cycloaliphatic or aromatic polyhydric alcohols comprising at least two hydroxyl groups, C ₇-C ₁₅ araliphatic polyhydric alcohols comprising at least two hydroxyl groups. More preferably, the at least one additional polyol is different from either one of the above diols and is selected from the group consisting of C ₂-C ₁₆ aliphatic polyhydric alcohols comprising at least two hydroxy groups, dimer of the C ₂-C ₁₆ aliphatic polyhydric alcohols comprising at least two hydroxy groups, trimer of the C ₂-C ₁₆ aliphatic polyhydric alcohols comprising at least two hydroxy groups, C ₆-C ₁₅ cycloaliphatic or aromatic polyhydric alcohols comprising at least two hydroxy groups, C ₇-C ₁₅ araliphatic polyhydric alcohols comprising at least two hydroxy groups, C ₂-C ₁₀ alkanolamine comprising at least one hydroxyl group and at least one amino group, vegetable oil having at least two hydroxyl groups, and a combination thereof.

According to an embodiment of the present disclosure, the isocyanate-reactive component (ii) further comprises at least one polyol other than the unsaturated linear diol represented by Formula I. For example, the polyol can be selected from the group consisting of C ₂-C ₁₆ aliphatic polyhydric alcohols comprising at least two hydroxyl groups, C ₆-C ₁₅ cycloaliphatic or aromatic polyhydric alcohols comprising at least two hydroxyl groups, C ₇-C ₁₅ araliphatic polyhydric alcohols comprising at least two hydroxyl groups, polyester polyols having a molecular weight from 100 to 12,000 and an average hydroxyl functionality of 1.1 to 8.0, a polyether polyol having a molecular weight from 100 to 12,000 and an average hydroxyl functionality of 1.1 to 8.0, a polymer polyol having a core phase and a shell phase based on polyether/polyester polyol, and any combinations thereof. According to another embodiment of the present disclosure, the polyol other than the unsaturated linear diol represented by Formula I can be selected from the group consisting of C ₂-C ₁₆ aliphatic polyhydric alcohols comprising at least two hydroxy groups, dimer of the C ₂-C ₁₆ aliphatic polyhydric alcohols comprising at least two hydroxy groups, trimer of the C ₂-C ₁₆ aliphatic polyhydric alcohols comprising at least two hydroxy groups, C ₆-C ₁₅ cycloaliphatic or aromatic polyhydric alcohols comprising at least two hydroxy groups, C ₇-C ₁₅ araliphatic polyhydric alcohols comprising at least two hydroxy groups, polyester polyols having a molecular weight from 500 to 5,000, polycarbonate polyols having an average functionality of 2 to 5 and a molecular weight from 200 to 5,000, polyether polyols having an average functionality of 2 to 5 and an average molecular weight of 200 to 12,000, C ₂-C ₁₀ alkanolamine comprising at least one hydroxyl group and at least one amino group, vegetable oil having at least two hydroxyl groups, and a combination thereof.

In an embodiment of the present disclosure, the polyether polyol used for component (ii) has a molecular weight of 100 to 10,000 g/mol, and may have a molecular weight in the numerical range obtained by combining any two of the following end point values: 120, 150, 180, 200, 250, 300, 350, 400, 450, 500, 550, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, 5000, 5100, 5200, 5500, 5800, 6000, 6200, 6500, 6800, 7000, 7200, 7500, 7800, 8000, 8200, 8500, 8800, 9000, 9200, 9500, 9800, and 10000 g/mol. In an embodiment of the present disclosure, the polyether polyol used for component (ii) has an average hydroxyl functionality of 1.0 to 8.0, or from 1.5 to 5.0, and may have an average hydroxyl functionality in the numerical range obtained by combining any two of the following end point values: 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8 and 7.9. According to a preferable embodiment of the present disclosure, the polyether polyol is selected from the group consisting of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (2-methyl-1, 3-propane glycol) and any copolymers thereof, such as poly (ethylene oxide-propylene oxide) glycol. According to another embodiment of the present application, the polyether polyol can be polytetramethylene glycol (PTMEG) having a molecular weight of 200 to 3,000 and a hydroxyl functionality of 1.0 to 3.0. According to another embodiment of the present application, starting material polyether polyol can be a poly (ethylene oxide-propylene oxide) glycol having a molecular weight of 200 to 3,000 and a hydroxyl functionality of 2.0 to 8.0, wherein the molar ratio between the ethylene oxide repeating unit and the propylene oxide repeating unit can be from 5/95 to 95/5, such as from 10/90 to 90/10, or from 20/80 to 80/20, or from 40/60 to 60/40, or at about 50/50.

According to a preferable embodiment of the present application, the polymer polyol is a composite particulate having a core-shell structure, wherein the core is a micro-sized or nano-sized core composed of any polymer or copolymer, such as SAN (styrene and acryl nitrile) , and the shell phase is composed of a polyether polyol, such as PO-EO polyol. According to another embodiment of the present application, the polymer polyol has a shell phase based on the poly (C ₂-C ₁₀) alkylene glycol or copolymer thereof. Preferably, the polymer polyol has a core phase and a shell phase based on the poly (C ₂-C ₁₀) alkylene glycol or copolymer thereof, having a solid content of 1-50%, an OH value 10 ～ 149, and a hydroxyl functionality of 1.5-5.0, such as 2.0-5.0. The shell phase may comprise at least one poly (C ₂-C ₁₀) alkylene glycol or copolymer thereof, for example, the polyol may be selected from the group consisting of polyethylene, (methoxy) polyethylene glycol (MPEG) , polyethylene glycol (PEG) , poly (propylene glycol) , polytetramethylene glycol, poly (2-methyl-1, 3-propane glycol) or copolymer of ethylene epoxide and propylene epoxide (polyethylene glycol-propylene glycol) with primary hydroxyl ended group or secondary hydroxyl ended group. The core phase may be micro-sized and may comprise any polymers compatible with the shell phase. For example, the core phase may comprise polystyrene, polyacrylnitrile, polyester, polyolefin or polyether different (in either composition or polymerization degree) from those of the shell phase. According to a preferable embodiment of the present application, the polymer polyol is a composite particulate having a core-shell structure, wherein the core is a micro-sized core composed of SAN (styrene and acryl nitrile) and the shell phase is composed of PO-EO polyol. Such a polymer polyol can be prepared by free radical copolymerization of styrene, acryl nitrile and poly (EO-PO) polyol comprising ethylenically unsaturated groups.

According to an embodiment of the present disclosure, the polyether polyols can be prepared by polymerization of one or more linear or cyclic alkylene oxides selected from propylene oxide (PO) , ethylene oxide (EO) , butylene oxide, tetramethylene glycol, tetrahydrofuran, 2-methyl-1, 3-propane glycol and mixtures thereof, with proper starter molecules in the presence of a catalyst. Typical starter molecules include compounds having at least 1, preferably from 1.5 to 3.0 hydroxyl groups or having one or more primary amine groups in the molecule. Suitable starter molecules having at least 1 and preferably from 1.5 to 3.0 hydroxyl groups in the molecules are for example selected from the group comprising ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butenediol, 1, 4-butynediol, 1, 5-pentanediol, neopentyl glycol, 1, 4-bis (hydroxymethyl) -cyclohexane, 1, 2-bis (hydroxymethyl) cyclohexane, 1, 3-bis (hydroxymethyl) -cyclohexane, 2-methylpropane-1, 3-diol, methylpentanediols, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol, polybutylene glycols, trimethylolpropane, glycerol, pentaerythritol, castor oil, sugar compounds such as, for example, glucose, sorbitol, mannitol and sucrose, polyhydric phenols, resols, such as oligomeric condensation products of phenol and formaldehyde and Mannich condensates of phenols, formaldehyde and dialkanolamines, and also melamine. Starter molecules having 1 or more primary amine groups in the molecules may be selected for example from the group consisting of aniline, EDA, TDA, MDA and PMDA, more preferably from the group comprising TDA and PMDA, an most preferably TDA. When TDA is used, all isomers can be used alone or in any desired mixtures. For example, 2, 4-TDA, 2, 6-TDA, mixtures of 2, 4-TDA and 2, 6-TDA, 2, 3-TDA, 3, 4-TDA, mixtures of 3, 4-TDA and 2, 3-TDA, and also mixtures of all the above isomers can be used. Catalysts for the preparation of polyether polyols may include alkaline catalysts, such as potassium hydroxide, for anionic polymerization or Lewis acid catalysts, such as boron trifluoride, for cationic polymerization. Suitable polymerization catalysts may include potassium hydroxide, cesium hydroxide, boron trifluoride, or a double cyanide complex (DMC) catalyst such as zinc hexacyanocobaltate or quaternary phosphazenium compound. In a preferable embodiment of the present disclosure, the starting material polyether polyol includes polyethylene, (methoxy) polyethylene glycol (MPEG) , polyethylene glycol (PEG) , poly (propylene glycol) , polytetramethylene glycol, poly (2-methyl-1, 3-propane glycol) or copolymer of ethylene epoxide and propylene epoxide (polyethylene glycol-propylene glycol) with primary hydroxyl ended group or secondary hydroxyl ended group.

According to various embodiments of the present disclosure, the isocyanate component (i) comprises at least one monomeric compound having at least two isocyanate groups, or at least one prepolymer having at least two isocyanate groups, or a mixture thereof. According to an embodiment of the present disclosure, the isocyanate component (B) has an average NCO functionality of at least about 1.5, preferably from about 2 to 10, more preferably from about 2 to about 8, more preferably from about 2 to about 6, and most preferably about 2. Preferably, the isocyanate component (B) has an average NCO functionality of 2.0.

In the context of the present disclosure, the terms “prepolymer” , “prepolymer of isocyanate” and “polyurethane prepolymer” are used interchangeably and refer to a prepolymer prepared by reacting at least one isocyanate compound having at least two isocyanate groups with a polyol, wherein the prepolymer comprises at least two isocyanate groups and is used for further reacting with the isocyanate-reactive component (ii) to form the polyurethane product such as microcellular polyurethane foam. In the context of the present disclosure, the terms “polyisocyanate compound” , “polyisocyanate” and “isocyanate compound comprising at least two isocyanate groups” are used interchangeably and refer to an isocyanate having at least two isocyanate groups, wherein the isocyanate is monomeric, dimeric, trimeric or oligomeric (such as having a polymerization degree of 2, 3, 4, 5 or 6) .

According to an embodiment of the present disclosure, the monomeric compound having at least two isocyanate groups is selected from the group consisting of C ₄-C ₁₂ aliphatic isocyanate comprising at least two isocyanate groups, C ₆-C ₁₅ cycloaliphatic or aromatic isocyanate comprising at least two isocyanate groups, C ₇-C ₁₅ araliphatic isocyanate comprising at least two isocyanate groups, and any combinations thereof. For example, the monomeric compound having at least two isocyanate groups may include m-phenylene diisocyanate, 2, 4-toluene diisocyanate and/or 2, 6-toluene diisocyanate (TDI) , diphenylmethanediisocyanate (MDI) , carbodiimide modified MDI products, hexamethylene-1, 6-diisocyanate, tetramethylene-1, 4-diisocyanate, cyclohexane-1, 4-diisocyanate, hexahydrotoluene diisocyanate, hydrogenated MDI, naphthylene-1, 5-diisocyanate, isophorone diisocyanate (IPDI) , isomers of naphthalene-dipolyisocyanate (NDI) such as 1, 5-NDI, isomers of hexamethylene dipolyisocyanate (HDI) , isomers of isophorone dipolyisocyanate (IPDI) , isomers of xylene dipolyisocyanate (XDI) , or mixtures thereof. According to a preferable embodiment of the present disclosure, the isocyanate compound can be a quasi-prepolymer formed by reacting a monomeric MDI with one or more polyols. According to a preferable embodiment of the present disclosure, the isocyanate compound is at least one aromatic isocyanate as stated above, having a NCO content between 12-32%and a viscosity below 1500 mPa·s at room temperature. Generally, the amount of the isocyanate compound may vary based on the actual requirement of the polyurethane products. For example, as one illustrative embodiment, the content of the isocyanate compound can be from 15 wt%to 60 wt%, or from 20 wt%to 50 wt%, or from 23 wt%to 40 wt%, or from 25 wt%to 35 wt%, based on the combined weight of the isocyanate component (i) and the isocyanate-reactive component (ii) . According to a preferable embodiment of the present disclosure, the amount of the isocyanate compound is properly selected so that the isocyanate group is present at a stoichiometric molar amount relative to the total molar amount of the hydroxyl groups included in the isocyanate-reactive component and any additional additives or modifiers.

According to another embodiment of the present disclosure, the isocyanate component (i) comprises at least one prepolymer having at least two isocyanate groups, wherein the prepolymer is formed by the reaction of one or more (monomeric) isocyanate compounds comprising at least two isocyanate groups, preferably comprising two isocyanate groups, with one or more isocyanate-reactive compounds having at least two isocyanate-reactive groups; wherein the prepolymer comprises at least two free isocyanate groups, preferably comprises two free isocyanate groups. According to a preferable embodiment, the isocyanate compound used for preparing the prepolymer is selected from the above stated monomeric compound having at least two isocyanate groups, and the isocyanate-reactive compound used for preparing the prepolymer may comprise the above stated polyols for the isocyanate-reactive component (ii) .

Generally, the amounts of the above said monomeric isocyanate compound and/or prepolymer may vary based on the actual requirement of the microcellular polyurethane foam and the polyurethane tire. For example, as one illustrative embodiment, the content of the monomeric isocyanate compound and/or prepolymer can be from 10 wt%to 70 wt%, or from 15 wt%to 60 wt%, or from 20 wt%to 50 wt%, or from 23 wt%to 40 wt%, or from 25 wt%to 35 wt%, based on the combined weight of the isocyanate component (i) and the isocyanate-reactive component (ii) . According to a preferable embodiment of the present disclosure, the amount of the monomeric isocyanate compound/prepolymer is properly selected so that the isocyanate group is present at a stoichiometric molar amount relative to the total molar amount of the hydroxyl groups included in the isocyanate-reactive component, and any additional additives or modifiers. According to another embodiment of the present disclosure, the prepolymer has a NCO group content of from 5 to 60 wt%, preferably from 6 to 49 wt%, based on the total weight of the prepolymer.

The reaction for preparing the prepolymer and the reaction between the isocyanate component (i) and the isocyanate-reactive component (ii) may occur in the presence of one or more catalysts that can promote the reaction between the isocyanate group and the hydroxyl group. Without being limited to theory, the catalysts can include, for example, glycine salts; tertiary amines; tertiary phosphines, such as trialkylphosphines and dialkylbenzylphosphines; morpholine derivatives; piperazine derivatives; chelates of various metals, such as those which can be obtained from acetylacetone, benzoylacetone, trifluoroacetyl acetone, ethyl acetoacetate and the like with metals such as Be, Mg, Zn, Cd, Pd, Ti, Zr, Sn, As, Bi, Cr, Mo, Mn, Fe, Co and Ni; acidic metal salts of strong acids such as ferric chloride and stannic chloride; salts of organic acids with variety of metals, such as alkali metals, alkaline earth metals, Al, Sn, Pb, Mn, Co, Ni and Cu; organotin compounds, such as tin (II) salts of organic carboxylic acids, e.g., tin (II) diacetate, tin (II) dioctanoate, tin (II) diethylhexanoate, and tin (II) dilaurate, and dialkyltin (IV) salts of organic carboxylic acids, e.g., dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate; bismuth salts of organic carboxylic acids, e.g., bismuth octanoate; organometallic derivatives of trivalent and pentavalent As, Sb and Bi and metal carbonyls of iron and cobalt; or mixtures thereof. According to an embodiment of the present disclosure, the tertiary amine, morpholine derivative and piperazine derivative catalysts can include, by way of example and not limitation, triethylenediamine, tetramethylethylenediamine, pentamethyl-diethylene triamine, bis (2-dimethylaminoethyl) ether, triethylamine, tripropylamine, tributyl-amine, triamylamine, pyridine, quinoline, dimethylpiperazine, piperazine, N-ethylmorpholine, 2-methylpropanediamine, methyltriethylenediamine, 2, 4, 6-tridimethylamino-methyl) phenol, N, N’, N”-tris (dimethyl amino-propyl) sym-hexahydro triazine, or mixtures thereof. In general, the content of the catalyst used herein is larger than zero and is at most 3.0 wt%, preferably at most 2.5 wt%, more preferably at most 2.0 wt%, and can be in the numerical range obtained by combining any two of the following end point values: 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2.0 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%and 3.0 wt%, based on the total weight of the polyurethane product.

In various embodiments of the present disclosure, the raw materials for preparing the polyurethane product comprise one or more additives selected from the group consisting ofchain extenders, crosslinkers, blowing agents, foam stabilizers, tackifiers, plasticizers, rheology modifiers, antioxidants, fillers, colorants, pigments, water scavengers, surfactants, solvents, diluents, flame retardants, slippery-resistance agents, antistatic agents, preservatives, biocides, antioxidants and combinations of two or more thereof. These additives can be transmitted and stored as independent components and incorporated into the mold shortly or immediately before the combination of components (i) and (ii) . Alternatively, these additives may be contained in either of components (i) and (ii) when they are chemically inert to the isocyanate group or the isocyanate-reactive group.

A chain extender may be present in the reactants that form the polyurethane products. A chain extender is a chemical having two or more isocyanate-reactive groups per molecule and an equivalent weight per isocyanate-reactive group of less than 300, preferably less than 200 and especially from 31 to 125. The isocyanate reactive groups are preferably hydroxyl, primary aliphatic or aromatic amino or secondary aliphatic or aromatic amino groups. Representative chain extenders include monoethylene glycol (MEG) , diethylene glycol, triethylene glycol, 1, 2-propylene glycol, dipropylene glycol, tripropylene glycol, 1, 4-butanediol, cyclohexane dimethanol, ethylene diamine, phenylene diamine, bis (3-chloro-4- aminophenyl) methane, dimethylthio-toluenediamine and diethyltoluenediamine. According to a preferable embodiment of the present disclosure, the chain extender is a short chain (such as C ₂ to C ₄) polyol exclusively comprising hydroxyl group as the isocyanate-reactive group, and is preferably monoethylene glycol. According to another preferable embodiment of the present disclosure, the chain extender is an aliphatic or cyclo-aliphatic C ₂-C ₁₂ polyol having a hydroxyl functionality of 2.0 to 8.0, such as 3.0 to 7.0, or from 4.0 to 6.0, or from 5.0 to 5.5, and can be selected from the group consisting of ethylene glycol, propane diol, butane diol, pentane diol, hexane diol, 1, 4-cyclohexane dimethanol, and their isomers. According to a preferable embodiment of the present disclosure, the chain extender is contained as part of the component (ii) .

According to a preferable embodiment of the present disclosure, the raw materials for preparing the polyurethane product do not include any additional crosslinkers as the crosslinking function is solely contributed by the unsaturated linear diol of Formula I.

A filler may be present in the polyurethane product to reduce cost and/or enhance the mechanical properties of the product. Particulate rubbery materials are especially useful fillers. Such a filler may constitute from 1 to 50%or more of the weight of the polyurethane product.

Suitable blowing agents include water, air, nitrogen, argon, carbon dioxide, hydrocarbons, hydrofluorocarbons, hydrochlorofluorocarbons and other volatile chemicals with low boiling points of from -30 ℃ to 75℃.

A surfactant may be present in the raw materials. It can be used, for example, if a cellular tire filling is desired, as the surfactant stabilizes a foaming reaction mixture until it can harden to form a cellular polymer. A surfactant also may be useful to wet filler particles and thereby help disperse them into the reaction mixture and the resultant foam. Silicone surfactants are widely used for this purpose. The amount of surfactant used will in general be between 0.02 and 1 part by weight per 100 parts by weight of the isocyanate reactive component (ii) .

According to a preferable embodiment of the present disclosure, one or more foam stabilizer, such as silicone-based foam stabilizers; anti-foam agents, such as silicone-based anti-foam agents; functional additives, such as anti-static electricity agents, flame-retardant agents, slippery resistance agents, and etc. may be further included in the polyurethane composition.

According to another embodiment of the present disclosure, the polyurethane composition comprises at least one of colorant, pigment and dye. The colorant, pigment and dye can be included in either component (i) or component (ii) , and are preferably included in component (ii) but not in component (i) . According to a preferable embodiment of the present disclosure, the colorant, pigment and dye include carbon black, titanium dioxide or isoindolinon. According to a preferable embodiment of the present disclosure, the amount of each of the colorant, pigment and dye is from 0.3 to 3.0%by weight, based on the total weight of the component (ii) . For example, the colorant, pigment or dye can be added as a dispersion in polyol, such as a dispersion in the isocyanate reactive component (ii) .

According to another embodiment of the present application, the polyurethane product of the present disclosure is a foamed polyurethane product, or a microcellular polyurethane foam. For example, the polyurethane foam is applicable to prepare a wide range of tires that can be used in many applications. The polyurethane product can be a solid tire for various vehicles such as bicycle, e-bike, cart such as golf cart or shopping cart, motorized or unmotorized wheelchair, automobile such as car, jeep or truck, any other type of transportation vehicles including an aircraft, as well as various types of agriculture, industrial and construction equipments. Large tires that have an internal volume of 0.1 cubic meter or more are of particular interest.

According to various embodiments of the present disclosure, the microcellular polyurethane foam has a density of at least 100 kg/m ³, such as from 100 to 950 kg/m ³, from 200 to 850 kg/m ³, from 300 to 800 kg/m ³, from 400 to 750 kg/m ³, from 500 to 700 kg/m ³, from 550 to 650 kg/m ³, or from 580 to 620 kg/m ³, or about 600 kg/m ³.

According to an embodiment of the present disclosure, it is surprisingly found that the particularly designed two-stage curing and the microphase separation step can ensure the complete curing and sufficient hard segment/soft segment phase separation, while the carbon-carbon double bond and the initiator having proper decomposition temperature are also particularly selected so that both of them are basically kept intact until the final crosslinking step, in which the C=C bond in the polyurethane backbone and the initiator effectively cooperate with each other to form the crosslinking structure within the polymer material which has been sufficiently cured and phase separated, thus superior performance properties such as higher mechanical strengths even at an elevated temperature, decreased internal heat buildup, improved heat resistance and the like, can be achieved. Besides, the technology of the present disclosure will not result in significantly increased cost.

The description hereinabove is intended to be general and is not intended to be inclusive of all possible embodiments of the disclosure. Similarly, the examples hereinbelow are provided to be illustrative only and are not intended to define or limit the invention in any way. Those skilled in the art will be fully aware that other embodiments, within the scope of the claims, will be apparent from consideration of the specification and/or practice of the invention as disclosed herein. Such other embodiments may include selections of specific components and constituents and proportions thereof; mixing and reaction conditions, vessels, deployment apparatuses, and protocols; performance and selectivity; identification of products and by-products; subsequent processing and use thereof; and the like; and that those skilled in the art will recognize that such may be varied within the scope of the claims appended hereto.

EXAMPLES

Some embodiments of the disclosure will now be described in the following Examples. However, the scope of the present disclosure is not, of course, limited to the formulations set forth in these examples. Rather, the Examples are merely inventive of the disclosure.

The information of the raw materials used in the examples is listed in the following table 2:

Table 2. Raw materials used in the examples

In the following Inventive Examples 1-5 and Comparative Examples 1-6, polyurethane foam samples were synthesized and characterized.

Characterization Technologies for the Inventive Examples 1-5 and Comparative Examples 1-6:

Tear strength were determined on a Gotech AI-7000S1 universal testing machine according to the testing method DIN 53543, and the general industrial requirement on tear strength is higher than 180 N/cm.

The storage modulus was characterized via Dynamic mechanical analysis (DMA) , wherein DMA was performed on a TA RSA G2 analyzer under strain-control mode at a frequency of 1 Hz and 0.1%strain, in a temperature range from -80 ℃ to 200 ℃ with a ramp rate of 3 ℃/min.

Differential scanning calorimeter (DSC) was performed on a TA Q1500 analyzer with a cooling speed of 10 ℃/min and heating speed of 20 ℃/min under N ₂ atmosphere.

In the Inventive Examples 1-5 and Comparative Examples 1-6, the isocyanate reactive component (Part A) were made by mixing the polyols, the linear unsaturated diol of Formula I, chain extenders, catalysts, blowing agents, silicon compounds and initiators according to the recipes as shown in Table 3 and 5. Then the isocyanate reactive component (Part A) was mixed with the isocyanate prepolymer (NE569) at room temperature with a high speed stirrer (at a stirring rate of 2500 RPM) for 7 seconds. The mixture was poured into a metal mold (which is lined with PTFE film to aid the demolding at a later stage) at 50 ℃ and then the mold was sealed immediately. The reaction between the isocyanate reactive component and prepolymer occurred instantly after the mixing, the reaction content was cured at 50℃ for 10 minutes to form the microcellular PU foam sample. The mold was opened and the foam sample was demolded. The foam sample was kept at room temperature of about 20 ℃ overnight, and was then heated in an oven at 50℃ for 24 hours. Then the properties of the foam sample before and after being heated at 105 ℃ for 1 hour were characterized.

Table 3. Formulations for the preparation of polyurethane foam in Comparative Examples (Com. Ex. ) 1-5 and Inventive Examples 1-3 (Inv. Ex. )

The characterization results of the samples prepared according to Comparative Examples and Inventive Examples of Table 3 were summarized in the following Table 4, wherein the experiments marked with “105℃” refer to the samples which have been heated at 105℃ for 1 hour.

Table 4 Characterization Results of Comparative Examples 1-5 and Inventive Examples 1-3

The Comparative Examples 1-2 do not comprise any initiator, Comparative Examples 3-5 comprise initiators having a T@t _1/2=1h of lower than 120 ℃, and Examples 1-3 comprise initiators having a T@t _1/2=1h of higher than 120 ℃. The samples of comparative examples 3 and 4 were too soft to be demolded. The sample of comparative example 5 can be demolded but exhibits inferior mechanical performance which will be further degraded after the heating treatment under 105 ℃, which could be due to improper microphase separation/crosslinking behaviors. On the contrary, all of the Inventive Examples 1-3, which were conducted by using initiators having a T@t _1/2=1h of higher than 120 ℃, exhibit superior mechanical strength properties both before and after the heating treatment under 105 ℃, while none of the comparative document can achieve such superior mechanical strength properties.

Furthermore, Inventive examples 4, 5 and comparative example 6 are further conducted by using different initiator amounts.

Table 5. Formulations for the preparation of polyurethane foam in Comparative Example (Com. Ex. ) 6 and Inventive Examples 1 and 4-5 (Inv. Ex. )

The characterization results of the samples prepared according to Comparative Examples and Inventive Examples of Table 5 were summarized in the following Table 6, wherein the experiments marked with “105℃” refer to the samples which have been heated at 105℃ for 1 hour. As shown in Table 6, good tear strength can be achieved when the initiator content is in the level of 1%to 10%, and 1-5%is a more preferable level which can achieve superior tear strength and further improvement of tear strength after the heating treatment.

Table 6 Characterization Results of Comparative Example 6 and Inventive Examples 1, 4 and 5

	Tear Strength (N)	Tensile Strength (N)
Com. Ex. 6	205	251
Com. Ex. 6-105℃	180	288
Inv. Ex. 4	237	296
Inv. Ex. 4-105℃	243	226
Inv. Ex. 1	233	285
Inv. Ex. 1-105℃	254	293
Inv. Ex. 5	210	230
Inv. Ex. 5-105℃	215	189

Claims

A process for preparing a polyurethane product, comprising:

(A) providing an isocyanate component (i) comprising at least one first isocyanate compound having at least two isocyanate groups, and an isocyanate-reactive component (ii) comprising at least one unsaturated linear diol represented by Formula I,

HO-R ₁-C (R ₂) =C (R ₃) -R ₄-OH Formula I

wherein each of R ₁ and R ₄ is independently selected from the group consisting of covalent bond, C ₁ to C ₆ alkylene group, C ₂-C ₆ alkenylene group, C ₆-C ₁₂ cycloalkylene group, and C ₆-C ₁₂ arylene group, and each of R ₂ and R ₃ is independently selected from the group consisting of hydrogen and C ₁-C ₆ alkyl group,

at least one polyol other than the unsaturated linear diol, and

at least one free radical initiator having a decomposition temperature above 120℃;

(B) combining the isocyanate component (i) with the isocyanate-reactive component (ii) to form a mixture; and

(C) subjecting the mixture to a multi-stage thermal treatment comprising

a low temperature treatment stage in which curing and microphase-separation are achieved without incurring the activation of the free radical initiator, and

a high temperature treatment stage in which the free radical initiator is activated to initiate the crosslinking of carbon-carbon double bond derived from the unsaturated linear diol represented by Formula I.
The process according to claim 1, wherein the low temperature treatment stage comprises:

(C1) curing the mixture at a first curing temperature of 20 ℃ to 60 ℃ to produce a pre-cured substance;

(C2) curing the pre-cured substance at a second curing temperature of 0 ℃ to 50 ℃ to produce a cured substance;

(C3) heating the cured substance at a first heating temperature of 30 ℃ to 80 ℃ to form a microphase-separated substance; and

the high temperature treatment stage comprises

(C4) heating the microphase-separated substance at a second heating temperature of 90 ℃ to 140 ℃ to produce the polyurethane product.
The process according to claim 1, wherein the free radical initiator is selected from the group consisting of tert-butyl peroxybenzoate, butyl 4, 4-di (tert-butylperoxy) valerate, di-tert-amyl peroxide, dicumyl peroxide, di (tert-butylperoxyisopropyl) benzene, 2, 5-dimethyl-2, 5-di (tert-butylperoxyl) hexane, tert-butyl cumyl peroxide, 2, 5-dimethyl-2, 5-di (tert-butylperoxyl) hexyne-3, di-tert-butyl peroxide, 3, 6, 9-triethyl-3, 6, 9-trimethyl-1, 4, 7-triperoxonane, isopropylcumyl hydroperoxide, 1, 1, 3, 3-tetramethylbutyl hydroperoxide, cumyl hydroperoxide, tert-butyl hydroperoxide, and any combinations thereof.
The process according to claim 1, wherein the unsaturated linear diol represented by Formula I is selected from the group consisting of 2-butene-1, 4-diol, 2-pentene-1, 5-diol, 2-hexene-1, 6-diol, 3-hexene-1, 6-diol, 2, 4-hexadiene-1, 6-diol, 2-heptene-1, 7-diol, 3-heptene-1, 7-diol, 2, 4-heptadiene-1, 7-diol, 2, 5-heptadiene-1, 7-diol, 2-octene-1, 8-diol, 3-octene-1, 8-diol, 4-octene-1, 8-diol, 2, 4-octadiene-1, 8-diol, 2, 5-octadiene-1, 8-diol, 2, 6-octadiene-1, 8-diol, 1, 2-bis (4-hydroxylcyclohexyl) ethylene, 1, 2-bis (3-hydroxylcyclohexyl) ethylene, 1, 2-bis (4-methylolcyclohexyl) ethylene, 1, 2-bis (3-methylolcyclohexyl) ethylene, 1, 2-bis (4-hydroxyl-phenyl) ethylene, 1, 2-bis (4-methylol-phenyl) ethylene, 1, 2-bis (4-hydroxyl-benzyl) -ethylene, 1, 2-bis (4-methylol-benzyl) ethylene, and any combinations thereof.
The process according to claim 1, wherein the isocyanate compound is selected from the group consisting of C ₄-C ₁₂ aliphatic isocyanate comprising at least two isocyanate groups, C ₆-C ₁₅ cycloaliphatic or aromatic isocyanate comprising at least two isocyanate groups, C ₇-C ₁₅ araliphatic isocyanate comprising at least two isocyanate groups, a prepolymer comprising at least two isocyanate groups, and any combinations thereof;

the polyol other than the unsaturated linear diol is selected from the group consisting of C ₂-C ₁₆ aliphatic polyhydric alcohols comprising at least two hydroxyl groups, C ₆-C ₁₅ cycloaliphatic or aromatic polyhydric alcohols comprising at least two hydroxyl groups, C ₇-C ₁₅ araliphatic polyhydric alcohols comprising at least two hydroxyl groups, polyester polyols having a molecular weight from 100 to 12,000 and an average hydroxyl functionality of 1.1 to 8.0, a polyether polyol having a molecular weight from 100 to 12,000 and an average hydroxyl functionality of 1.1 to 8.0, a polymer polyol having a core phase and a shell phase based on polyether/polyester polyol, and any combinations thereof; and each of the isocyanate component (i) and the isocyanate-reactive component (ii) independently and optionally further comprises at least one additive selected from the group consisting of chain extender, crosslinker, blowing agent, foam stabilizer, tackifier, plasticizer, rheology modifier, antioxidant, UV-absorbent, light-stabilizer, catalyst, cocatalyst, filler, colorant, pigment, water scavenger, surfactant, solvent, diluent, flame retardant, slippery-resistance agent, antistatic agent, preservative, biocide, supplemental initiator and any combinations thereof.
The process according to claim 1, wherein

the content of the unsaturated linear diol represented by Formula I is from 1%to 20%by weight, based on the total weight of the isocyanate-reactive component (ii) ; and

the content of the free radical initiator having a decomposition temperature above 120℃ is from 0.5%to 10%by weight based on the weight of the unsaturated linear diol represented by Formula I.
The process according to claim 1, wherein at least 70%by mole of the repeating units derived from the unsaturated linear diol represented by Formula I, based on the total molar amount of the unsaturated linear diol represented by Formula I contained in the isocyanate-reactive component (ii) , are present in the polyurethane backbone of the polyurethane product.
A polyurethane product prepared by the process according to any of claims 1 to 7.
The polyurethane product according to claim 8, wherein the polyurethane product is a solid tire for an equipment selected from the group consisting of e-bike, bicycle, motorcycle, automobile, cart, wheelchair and aircraft.
A composition for preparing a polyurethane product, comprising

(i) an isocyanate component comprising at least one first isocyanate compound having at least two isocyanate groups, and

(ii) an isocyanate-reactive component comprising

at least one unsaturated linear diol represented by Formula I,

HO-R ₁-C (R ₂) =C (R ₃) -R ₄-OH Formula I

wherein each of R ₁ and R ₄ is independently selected from the group consisting of covalent bond, C ₁ to C ₆ alkylene group, C ₂-C ₆ alkenylene group, C ₆-C ₁₂ cycloalkylene group, and C ₆-C ₁₂ arylene group, and each of R ₂ and R ₃ is independently selected from the group consisting of hydrogen and C ₁-C ₆ alkyl group,

at least one polyol other than the unsaturated linear diol, and

at least one free radical initiator having a decomposition temperature above 120℃.