CN117203257A - Polyurethane elastomer and method for producing same - Google Patents
Polyurethane elastomer and method for producing same Download PDFInfo
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- CN117203257A CN117203257A CN202280031232.6A CN202280031232A CN117203257A CN 117203257 A CN117203257 A CN 117203257A CN 202280031232 A CN202280031232 A CN 202280031232A CN 117203257 A CN117203257 A CN 117203257A
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Abstract
A polyurethane elastomer having excellent friction properties (low friction coefficient), high abrasion resistance and low hardness is provided. The polyurethane elastomer includes a first repeating structural unit represented by the general formula (1) and a second repeating structural unit represented by the general formula (2), and includes a matrix phase and a domain phase dispersed in the matrix phase, the matrix phase including the first repeating structural unit, and the domain phase including the second repeating structural unit.
Description
Technical Field
The present disclosure relates to polyurethane elastomers and methods of making polyurethane elastomers.
Background
Polyurethane elastomers are used in a wide range of applications such as artificial leather, synthetic leather, paints, coating agents, adhesives, and the like. Typically, polyurethane elastomers are formed from the reaction product of a polyisocyanate and a polyol, and include hard segments derived from the polyisocyanate and soft segments derived from the polyol. Polyols, which are one of the raw materials of the polyurethane elastomer, are classified into polyether polyols, polyester polyols, polycarbonate polyols, and the like depending on the difference of molecular chain structures, and the polyols are selected according to the desired properties. In particular, the polyurethane elastomer having a polycarbonate structure using a polycarbonate polyol as a raw material is excellent in abrasion resistance. Furthermore, it is known that: the polyurethane elastomer having a polycarbonate structure is also excellent in heat resistance, weather resistance, hydrolysis resistance, and the like, as compared with the polyurethane elastomer having a polyether structure or a polyester structure. Meanwhile, in the polyurethane elastomer having a polycarbonate structure, strong intermolecular forces act between the polycarbonate structures, resulting in a significant increase in the hardness of the polyurethane elastomer. Therefore, polyurethane elastomers having a polycarbonate structure are difficult to use in applications requiring low hardness.
Further, a typical example of the low-hardness elastomer is a silicone elastomer. Silicone elastomers have excellent compression set, but poor abrasion resistance, compared to polyurethane elastomers having a polycarbonate structure.
Against this background, there is a need for an elastomer having excellent abrasion resistance similar to polyurethane elastomers having a polycarbonate structure and low compression set comparable to silicone elastomers.
In patent document 1, a polyurethane elastomer is disclosed which includes a structural unit derived from a polyol, a structural unit derived from a polyether carbonate diol having a specific structure, and a structural unit derived from a polycarbonate diol having two repeating units having a specific structure and/or a polyalkylene ether diol having two repeating units having a specific structure. Further, in patent document 2, a developing blade for an electrophotographic apparatus is disclosed in which a blade member is bonded to a support. In addition, it is disclosed that the material of the blade member is a polyurethane elastomer which is a reaction product of a polyol compound and a polyisocyanate compound, and the polyol compound is a blend of polydimethylsiloxane having active hydrogen at least at each of both molecular terminals thereof, and polypropylene glycol.
[ reference List ]
[ patent literature ]
Patent document 1: japanese patent application laid-open No.2020-128461
Patent document 2: japanese patent application laid-open No.2000-29307
Disclosure of Invention
Problems to be solved by the invention
According to the studies conducted by the present inventors, the polyurethane elastomer disclosed in patent document 1 is excellent in flexibility as compared with the polycarbonate polyurethane of the related art, but it is difficult to achieve low hardness equivalent to that of a silicone elastomer. Further, in the polyurethane elastomer disclosed in patent document 1, it is difficult to achieve excellent friction properties comparable to those of usual polycarbonate polyurethane, probably because polyether segments are uniformly present in the polyurethane elastomer. Further, the polyurethane elastomer disclosed in patent document 2 is excellent in hardness and friction properties, but it is difficult to achieve low compression set comparable to that of silicone elastomers.
The present disclosure aims to provide a polyurethane elastomer having excellent friction properties (low friction coefficient), high abrasion resistance, and low hardness, and a method for producing the polyurethane elastomer.
Solution for solving the problem
According to one aspect of the present disclosure, there is provided a polyurethane elastomer comprising: a first repeating structural unit represented by the general formula (1); and a second repeating structural unit represented by the general formula (2), wherein the polyurethane elastomer comprises a matrix phase and a domain phase dispersed in the matrix phase, wherein the matrix phase comprises the first repeating structural unit, and wherein the domain phase comprises the second repeating structural unit:
[ chemical formula 1]
Wherein R is 1 Represents an alkylene group having 3 to 12 carbon atoms;
[ chemical formula 2]
Wherein R is 2 Represents an alkylene group having 3 to 6 carbon atoms.
According to another aspect of the present disclosure, there is provided a method for manufacturing the above polyurethane elastomer, the method comprising the steps of:
(i) Reacting a first polyether having at least one isocyanate group and a first polycarbonate polyol having at least two hydroxyl groups with each other to provide a urethane prepolymer having at least two hydroxyl groups;
(ii) Providing a dispersion in which droplets containing at least a portion of the urethane prepolymer are dispersed in a second polycarbonate polyol; and
(iii) A polyurethane elastomer-forming mixture containing a dispersion and a polyisocyanate having at least two isocyanate groups is prepared, and then the urethane prepolymer, the second polycarbonate polyol, and the polyisocyanate in the polyurethane elastomer-forming mixture are reacted with one another to form a polyurethane elastomer.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present disclosure, a polyurethane elastomer having excellent friction properties (low friction coefficient), high abrasion resistance, and low hardness, and a method of manufacturing the same can be obtained.
Drawings
Fig. 1 is a schematic view for explaining a method of manufacturing a polyurethane elastomer according to the present disclosure.
FIG. 2 is a graph showing a temperature-loss tangent (tan. Delta.) curve obtained by Dynamic Mechanical Analysis (DMA) of the polyurethane elastomer produced in example 1 and comparative examples 1 and 2.
FIG. 3 is a photograph showing a viscoelastic image of a cross section of the polyurethane elastomer produced in example 1 taken with a viscoelastic atomic force microscope (VE-AFM).
Detailed Description
Embodiments of the present disclosure are described below. The embodiments described below are merely examples, and the present disclosure is not limited to these embodiments.
The polyurethane elastomer according to the present disclosure includes, as the repeating structural units, a first repeating structural unit having a polycarbonate structure represented by the general formula (1) and a second repeating structural unit having a polyether structure represented by the general formula (2):
[ chemical formula 3]
Wherein R is 1 Represents an alkylene group having 3 to 12 carbon atoms;
[ chemical formula 4]
Wherein R is 2 Represents an alkylene group having 3 to 6 carbon atoms.
In addition, the polyurethane elastomer includes a matrix phase and a domain phase dispersed in the matrix phase. The matrix phase comprises polyurethane comprising first repeating structural units. In addition, the regiophase comprises a second repeat unit.
Polyurethanes obtained by the reaction between a polyol having a polycarbonate structure (polycarbonate polyol) and a polyisocyanate have strong intermolecular forces between carbonate groups. Thus, such polyurethanes exhibit mechanical properties such as excellent friction properties (low coefficient of friction) and high abrasion resistance. However, strong intermolecular forces result in increased hardness, and therefore such polyurethanes are unsuitable for soft polyurethane elastomer applications.
On the other hand, in general, polyurethanes obtained from the reaction between polyols having a polyether structure (polyether polyols) and polyisocyanates have weak intermolecular forces between ether groups. Therefore, the hardness is suppressed to be very low, and thus such polyurethane is suitable for use in a soft polyurethane elastomer. However, weak intermolecular forces lead to reduced mechanical properties (e.g. friction properties and abrasion resistance).
The polyurethane elastomer according to the present disclosure has a matrix-domain structure including a matrix phase and a domain phase. In addition, the matrix phase comprises polyurethane comprising first repeating structural units. In addition, the regiophase comprises a second repeat unit. With this configuration, the polyurethane elastomer can have excellent friction properties and high abrasion resistance while suppressing the hardness to be low. That is, in the polyurethane elastomer according to the present disclosure, a function of imparting excellent friction properties and high abrasion resistance to the matrix phase and a function of imparting hardness reduction to the domain phase are imparted. As described above, the polyurethane elastomer according to the present disclosure can achieve excellent friction properties, high abrasion resistance, and low hardness at a higher level by imparting different functions to the matrix phase and the domain phase, respectively.
Further, by such a configuration as described above, the polyurethane elastomer according to the present disclosure can also achieve both low hardness and low compression set. The reason is considered as follows. The matrix phase and the domain phase are chemically connected to each other through urethane bonds at an interface therebetween, and thus the polyurethane elastomer exhibits excellent elasticity (entropy elasticity) without plastic deformation against external force such as compression. That is, it is considered that the entire domain phase has a function of soft crosslinking points by the action of entropy elasticity, and thus both low hardness and low compression set can be achieved.
In addition, it is preferable that in the temperature-loss tangent (tan δ) curve obtained by Dynamic Mechanical Analysis (DMA) of the polyurethane elastomer according to the present disclosure, there are at least two peaks ascribed to glass transition observed in a temperature range of-80 ℃ to +20 ℃. More preferably, there are at least two peaks ascribed to glass transition observed in the temperature range of-70 ℃ to 0 ℃. That is, the above two cases indicate that the polyurethane segment having the above polycarbonate structure and the polyurethane segment having the above polyether structure are significantly phase-separated from each other by the interface between the matrix phase and the domain phase. When peaks in the temperature-tan delta curve overlap each other, it is necessary to separate the individual peaks. Here, the peak separation in the temperature-tan. Delta. Curve can be performed by a known method.
Furthermore, it is preferable that at least one of peaks ascribed to glass transition is observed in a temperature range of-50 ℃ or less in a temperature-tan δ curve obtained by DMA of the polyurethane elastomer according to the present disclosure. It is also preferred that at least one of the peaks is in a temperature range above-40 ℃. More preferably, at least one of the peaks is in a temperature range of-60 ℃ or lower and at least one of the peaks is in a temperature range of-35 ℃ or higher. Typically, the peak ascribed to the glass transition of the polyether is observed in the temperature range from-80 ℃ to-50 ℃ or less. In addition, a peak ascribed to glass transition of the polycarbonate was observed in a temperature range of-40℃to +20℃. Thus, the presence of peaks ascribed to glass transition in two temperature ranges means the following.
In the polyurethane elastomer according to the present disclosure, the segment comprising the first repeating structural unit and the segment comprising the second repeating structural unit are phase separated. Thus, both segments are present, although being difficult to compatibilize with each other. This apparent phase separation inhibits the mixing of segments comprising the second repeat unit into the matrix phase. Thus, in the polyurethane elastomer according to the present disclosure, the matrix phase achieves excellent friction properties and high abrasion resistance.
A first repeating structural unit having a polycarbonate structure represented by the general formula (1) contained in a matrix phase of a polyurethane elastomer according to the present disclosure will be described. R in the general formula (1) 1 Represents an alkylene group having 3 to 12 carbon atoms. R is R 1 Preferably an alkylene group having 3 to 9 carbon atoms, more preferably an alkylene group having 3 to 6 carbon atoms. When R is 1 When an alkylene group having 3 to 12 carbon atoms is represented, low compatibility with a segment having a polyether structure represented by the general formula (2) is ensured, and a matrix phase and a domain phase can be markedly phase-separated. In addition, R is more preferable from the viewpoint of being able to suitably suppress intermolecular force between carbonate groups and being able to achieve both excellent friction properties and high abrasion resistance and low hardness 1 Containing an alkylene group having 3 to 12 carbon atoms. R is R 1 Examples of (C) include- (CH) 2 ) m - (m represents 3 to 12), -CH 2 C(CH 3 ) 2 CH 2 -、-CH 2 CH(CH 3 )CH 2 -and- (CH) 2 ) 2 CH(CH 3 )(CH 2 ) 2 -. In the polyurethane elastomer, all R 1 R may be the same or different 1 。
The number average molecular weight (Mn) of the polycarbonate structure represented by the general formula (1) is preferably 500 or more and 10,000 or less as the repeating unit in the polyurethane elastomer. The number average molecular weight is based on the polycarbonate polyol as a raw material. The number average molecular weight is more preferably 700 or more and 8,000 or less. It is preferable that the number average molecular weight is 500 or more because low compatibility with the polyurethane segment having the polyether structure of the repeating structural unit represented by the general formula (2) can be ensured and phase separation between the matrix phase and the regio-phase is clear. Further, by setting the number average molecular weight to 10,000 or less, an increase in the viscosity of the polycarbonate polyol as a raw material can be suppressed.
The number average molecular weight of the polyol and the like described later and the number average molecular weight of the polycarbonate structure are obtained by using standard polystyreneThe conversion of the molecular weight of the alkene or the value calculated from the hydroxyl number (mgKOH/g) and the valence number. For example, the number average molecular weight converted based on the molecular weight of polystyrene can be measured by using high performance liquid chromatography. The number average molecular weight may be determined by using, for example, 2 columns in series in a high-speed GPC apparatus "HLC-8220GPC" manufactured by Tosoh Corporation: shodex GPCLF-804 (exclusion limit molecular weight: 2X 10) 6 Separation range: 300 to 2X 10 6 ) To be measured. When hydroxyl numbers and valence numbers are used, the number average molecular weight can be calculated by the following mathematical expression. For example, the number average molecular weight of a polyol having a hydroxyl value of 56.1mgKOH/g and a valence of 2 can be calculated to be 2,000.
Number average molecular weight=56.1×1,000×valence number/hydroxyl number
In the second repeating structural unit represented by the general formula (2) contained in the domain phase, R 2 Represents an alkylene group having 3 to 6 carbon atoms. R is R 2 Preferably, the alkylene group includes an alkylene group having a branched structure in which 3 to 5 carbon atoms are present, and more preferably, an alkylene group having a branched structure in which 3 or 4 carbon atoms are present. When R is 2 When an alkylene group having 3 to 6 carbon atoms is represented, low compatibility with a polyurethane segment having a polycarbonate structure represented by the general formula (1) is ensured, and a matrix phase and a domain phase can be markedly phase-separated. In addition, R is more preferable from the viewpoint of being able to suppress the intermolecular force between ether groups to be very low and to achieve low hardness 2 Containing an alkylene group having a branched structure in which 3 to 5 carbon atoms are present. R is R 2 Examples of (C) include- (CH) 2 ) m - (m represents 3 to 6), -CH 2 CH(CH 3 )-、-CH 2 C(CH 3 ) 2 CH 2 -、-CH 2 CH(CH 3 )CH 2 -、-(CH 2 ) 2 CH(CH 3 )CH 2 -and- (CH) 2 ) 2 CH(CH 3 )(CH 2 ) 2 -. In the polyurethane elastomer, all R 2 R may be the same or different 2 。
The polyether structure represented by the general formula (2) preferably has a number average molecular weight (Mn) of 1,000 to 50,000 as a repeating unit in the polyurethane elastomer. The number average molecular weight is based on the polyether polyol as a raw material. The number average molecular weight is more preferably 1,200 or more and 30,000 or less. When the number average molecular weight is 1000 or more, low compatibility with the polyurethane segment having the polycarbonate structure represented by the general formula (1) is ensured, and phase separation between the matrix phase and the regio-phase can be further clarified. In addition, when the number average molecular weight is 50,000 or less, the segment having a polyether structure easily forms a regiophase, and the phase separation structure can be further stabilized.
The area ratio of the matrix phase to the domain phase in the cross section of the polyurethane elastomer according to the present disclosure is preferably 40/60 to 90/10, more preferably 45/55 to 80/20. It is preferable that the area ratio of the matrix phase to the domain phase falls within the above range because the phase separation morphology is stabilized, tending to form the matrix phase and the domain phase easily and stably.
The average diameter of the domain phase is preferably in the range of 0.2 μm to 30 μm, more preferably in the range of 0.5 μm to 20 μm. It is preferable that the average diameter falls within the above range because low hardness is ensured when the average diameter is 0.2 μm or more, and the phase separation morphology is stabilized when the average diameter is 30 μm or less.
The area ratio of the matrix phase to the domain phase and the average diameter of the domain phase can be calculated by, for example, a known method from a sectional image of the polyurethane elastomer obtained by an optical microscope, a Visco-elastic atomic force microscope (Visco-Elasticity Atomic Force Microscopy, or VE-AFM), or a scanning electron microscope.
In addition, the chemical structures of the components contained in the matrix phase and the regional phase can be analyzed using, for example, a spectrum analyzer such as an AFM infrared spectrum analyzer, a micro infrared spectrum analyzer, or a micro raman spectrum analyzer, a mass spectrometer, or the like.
The polyurethane elastomer according to the present disclosure may be synthesized by, for example, a method comprising the following steps (i) to (iii):
step (i): a step of reacting a first polyether having at least one isocyanate group and a first polycarbonate polyol having at least two hydroxyl groups with each other to provide a urethane prepolymer having at least two hydroxyl groups.
Step (ii): providing a dispersion in which droplets containing at least a portion of the urethane prepolymer are dispersed in a second polycarbonate polyol; and
step (iii): a step of preparing a polyurethane elastomer-forming mixture containing the dispersion and a polyisocyanate having at least two isocyanate groups, and then reacting the urethane prepolymer, the second polycarbonate polyol and the polyisocyanate in the polyurethane elastomer-forming mixture with each other to form a polyurethane elastomer.
One embodiment of a method of manufacturing a polyurethane elastomer according to an aspect of the present disclosure is described with reference to fig. 1. The method of manufacturing the polyurethane elastomer according to the present disclosure is not limited to this embodiment.
In step (i), a first polyether 51 having at least one isocyanate group and a first polycarbonate polyol 52 having at least two hydroxyl groups are mixed. Next, the isocyanate groups and the hydroxyl groups in the resulting mixture are reacted with each other in the presence of a curing catalyst to be connected to each other through urethane bonds, thereby providing a urethane prepolymer 53 having at least two hydroxyl groups. In fig. 1, a polyether having two isocyanate groups is shown as an example of the first polyether 51.
In step (ii), the urethane prepolymer 53 obtained in step (i) is dispersed in a second polycarbonate polyol 55. The segment from the first polyether 51 contained in the urethane prepolymer 53 forms droplets 54 without being compatible with the second polycarbonate polyol 55. On the other hand, by the segment derived from the first polycarbonate polyol 52 contained in the urethane prepolymer 53, the droplets 54 containing the segment derived from the first polyether forming part of the urethane prepolymer are uniformly and stably dispersed in the second polycarbonate polyol 55. As a result, a dispersion in which droplets 54 containing segments of the first polyether 51 derived from the urethane prepolymer 53 are dispersed in the second polycarbonate polyol 55 is obtained. For ease of description, steps (i) and (ii) are described separately, but these steps may be a continuous series of steps.
In step (ii), the second polycarbonate polyol 55 in which the droplets 54 are dispersed may be an unreacted product with the first polyether in the first polycarbonate polyol used in step (i). That is, by using an excess of the first polycarbonate polyol relative to the first polyether in step (i), a dispersion in which the urethane prepolymer 53 is dispersed in an excess of the first polycarbonate polyol (i.e., the second polycarbonate polyol 55 described in step (ii)) can be obtained. Even when the first polycarbonate polyol 52 is excessively used, a polycarbonate polyol (second polycarbonate polyol 55) used as a dispersion medium for the urethane prepolymer may be additionally added. In this case, the added polycarbonate polyol may have the same chemical composition as the first polycarbonate polyol used in step (i), or may be different therefrom.
On the other hand, when the first polycarbonate polyol 52 and the first polyether 51 are reacted with each other in equal amounts and all of the first polycarbonate polyol 52 is consumed in step (i), a new polycarbonate polyol is used as the second polycarbonate polyol to prepare a dispersion in step (ii). Also in this case, the polycarbonate polyol used as the second polycarbonate polyol 55 may have the same chemical composition as the first polycarbonate polyol 52, or may be different therefrom.
Finally, in step (iii), a polyurethane elastomer forming mixture is prepared containing the dispersion prepared in step (ii) and a polyisocyanate 56 having at least 2 isocyanate groups. Then, the terminal hydroxyl groups of the urethane prepolymer 53, the hydroxyl groups of the second polycarbonate polyol 55 and the isocyanate groups of the polyisocyanate 56 in the polyurethane elastomer-forming mixture are reacted with each other. Thereby, a network structure through urethane bonds is formed, and the polyurethane elastomer-forming mixture is cured to provide a polyurethane elastomer according to the present disclosure. The polyurethane elastomer 33 thus obtained has a matrix-domain structure in which domains 32 containing a polyether structure (i.e., a second repeating structural unit) derived from the first polyether 51 are dispersed in a matrix 31 containing a polyurethane elastomer having a polycarbonate structure (i.e., a first repeating structural unit) derived from the first polycarbonate polyol 52 and the second polycarbonate polyol 55. In addition, the region 32 mainly includes a polyether structural portion (second repeating structural unit), and the inside of the region 32 may be substantially free of a crosslinked structure. In other words, the region 32 may be present in the matrix 31 in a substantially liquid state. With this configuration, in the polyurethane elastomer 33 according to the present disclosure, the region 32 may have a low elastic modulus.
Further, with respect to the region 32, the liquid portion is not limited only in the matrix 31, but the region 32 and the matrix 31 are chemically bonded to each other through a urethane bond in a boundary portion between the region 32 and the matrix. Thus, when the load applied to the polyurethane elastomer 33 is removed, the recovery from deformation of the region 32 may be associated with the recovery from deformation of the base 31. That is, the substantially liquid form of the region 32 is substantially free of cross-linked structures therein. Therefore, the region 32 deformed by applying a load to the polyurethane elastomer 33 is difficult to automatically recover from the deformation. However, in the polyurethane elastomer 33 according to the present disclosure, the region 32 is chemically bonded to the base 31 at the boundary portion with the base 31, and thus the region 32 can also recover from deformation together with the recovery of deformation of the base 31. As a result, even when the polyurethane elastomer 33 is repeatedly subjected to loading and unloading, stable deformation (deformation amount) and stable recovery from the deformation are achieved.
Steps (i) and (ii) are steps of stably dispersing polyether which is originally low in compatibility with polyol, difficult to stably and uniformly disperse therein in polyol. That is, steps (i) and (ii) are steps of reacting the first polyether 51 and the first polycarbonate polyol 52 with each other to form the urethane prepolymer 53, thereby providing a dispersion in which the segment of the polyether derived from the first polyether 51 is stably and uniformly dispersed in the second polycarbonate polyol 55. As a result, it is possible to manufacture the polyurethane elastomer 33 in which the regions 32 having a high degree of circularity, a small size in the micrometer scale, and a relatively uniform size distribution are dispersed in the polyurethane 31 serving as the matrix.
As another method of mixing materials having low compatibility with each other, for example, a method of mixing and dispersing materials using high shear force is given. However, in this method, as a result of applying a high shear force to the polyether, the shape of the region is distorted to reduce the circularity, and the size of the region also becomes uneven. Furthermore, the dispersed state is also unstable, and the aggregation of the regions proceeds in a relatively short time. In addition, incompatibility between polyether and polycarbonate polyol cannot be ensured, and phase separation between the matrix and the region of the resulting polyurethane elastomer is unclear. Therefore, it is difficult to obtain such a polyurethane elastomer that provides an elastomer that is flexible and excellent in deformation recovery according to the present disclosure.
The first polyether is a polyether having at least one isocyanate group and a repeating structural unit represented by the general formula (2). The first polyether may be obtained, for example, by the following steps.
The polyether polyol having at least two hydroxyl groups and a repeating structural unit represented by the general formula (2) is reacted with a polyisocyanate having at least two isocyanate groups.
Examples of polyether polyols include: polyether polyols having an alkylene structure, such as polypropylene glycol, polytetramethylene glycol, a copolymer of tetrahydrofuran and neopentyl glycol, and a copolymer of tetrahydrofuran and 3-methyltetrahydrofuran; and random or block copolymers of these polyalkylene glycols. These polyether polyols may be used alone or in combination thereof.
Among the polyether polyols, amorphous polyether polyols are preferred from the viewpoint of achieving low compatibility with the second polycarbonate polyol described later and low hardness. More preferably, at least one selected from the group consisting of polypropylene glycol, a copolymer of tetrahydrofuran and neopentyl glycol, and a copolymer of tetrahydrofuran and 3-methyltetrahydrofuran is incorporated into the polyether polyol.
The number average molecular weight of the polyether polyol is preferably 1,000 or more and 50,000 or less, more preferably 1,200 or more and 30,000 or less. It is preferable that the number average molecular weight is 1,000 or more, because low compatibility with the polycarbonate polyol is ensured and phase separation between the matrix phase and the domain phase of the resulting polyurethane elastomer is clear. In addition, it is preferable that the number average molecular weight is 50,000 or less, because polyurethane segments derived from polyether polyols tend to easily form regio-phases and the phase separation morphology is stabilized.
Examples of the polyisocyanate to be reacted with the polyether polyol include pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, a trimer compound (isocyanurate) or a polymer compound of any of these polyisocyanates, allophanate type polyisocyanate, biuret type polyisocyanate, and water-dispersible type polyisocyanate. These polyisocyanates may be used alone or in combination thereof.
Among the polyisocyanates exemplified above, difunctional isocyanates having 2 isocyanate groups are preferable because of their high compatibility with polyether polyols and easy adjustment of physical properties such as viscosity. Of the above polyisocyanates, at least one selected from hexamethylene diisocyanate, isophorone diisocyanate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, xylylene diisocyanate and diphenylmethane diisocyanate is more preferably incorporated.
In the step of reacting the polyether polyol and the polyisocyanate with each other to provide the first polyether, the isocyanate index is preferably in the range of 0.05 to 8.0, more preferably in the range of 0.1 to 5.0. When the isocyanate index falls within the above range, the amount of the component derived from the first polyether remaining without forming the network structure is reduced, and bleeding of the liquid substance from the polyurethane elastomer can be suppressed. The isocyanate index represents the ratio of the number of moles of isocyanate groups in the isocyanate compound to the number of moles of hydroxyl groups in the polyol compound ([ NCO ]/[ OH ]).
The first polyether obtained by the reaction between the first polyether polyol and the polyisocyanate has a structure in which hydroxyl groups and isocyanate groups are reacted with each other so as to be connected to each other through urethane bonds. The number average molecular weight is preferably 1,000 to 100,000, more preferably 1,200 to 50,000.
The first polycarbonate polyol is a polycarbonate polyol having at least 2 hydroxyl groups and a repeating structural unit represented by the general formula (1). Examples of the first polycarbonate polyol include a reaction product of a polyol and phosgene, and a ring-opening polymerization product of a cyclic carbonate (e.g., alkylene carbonate).
Examples of the polyhydric alcohol include propylene glycol, dipropylene glycol, trimethylene glycol, 1, 4-tetramethylene glycol, 1, 3-tetramethylene glycol, 2-methyl-1, 3-trimethylene glycol, 1, 5-pentamethylene glycol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 2, 4-diethyl-1, 5-pentanediol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (e.g., 1, 4-cyclohexanediol), and sugar alcohols (e.g., xylitol and sorbitol).
Examples of alkylene carbonates include trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate.
The number average molecular weight of the first polycarbonate polyol is preferably 500 or more and 10,000 or less, more preferably 700 or more and 8,000 or less. It is preferable that the number average molecular weight is 500 or more because low compatibility with the polyurethane segment having the polyether structure represented by the general formula (2) is ensured and phase separation between the matrix phase and the regio-phase can be further clarified. Further, it is preferable that the number average molecular weight is 10,000 or less, because it is possible to prevent the increase in viscosity of the polycarbonate polyol as a raw material, which makes handling difficult.
The number average molecular weight of the first polycarbonate polyol can be calculated in the same manner as the number average molecular weight of the polyether polyol by using the hydroxyl value (mgKOH/g) and the valence.
The same polyisocyanates as those exemplified above as the raw material for the first polyether may each be used as the polyisocyanate 56 having at least 2 isocyanate groups to be used in step (iii). These polyisocyanates may be used alone or in combination thereof.
From the viewpoint that the elastic modulus of the matrix can be improved, among the above-exemplified polyisocyanates, the first polyisocyanate preferably includes a polyisocyanate having at least 3 isocyanate groups, for example, a trimer compound (isocyanurate) or a polymer compound of a polyisocyanate, an allophanate type polyisocyanate, a biuret type polyisocyanate, or the like. The first polyisocyanate more preferably includes any one of a trimer compound (isocyanurate) of pentamethylene diisocyanate, a trimer compound (isocyanurate) of hexamethylene diisocyanate, and a polymer compound of diphenylmethane diisocyanate. The curing catalysts of polyurethane elastomers are roughly classified into urethane catalysts (reaction promoting catalysts) and isocyanurate catalysts (isocyanate trimerization catalysts) for promoting rubberizing (resinification) and foaming. In the present disclosure, these polyisocyanates may be used alone or as a mixture thereof.
Examples of urethanization catalysts include: tin-based urethanization catalysts such as dibutyltin dilaurate, stannous octoate, and the like; and amine-based urethanization catalysts such as triethylenediamine, tetramethylguanidine, pentamethyldiethylenetriamine, diethylimidazole, tetramethylpropylenediamine, and N, N, N' -trimethylaminoethylethanolamine, etc. These urethanization catalysts may be used alone or as a mixture thereof.
Among these urethanization catalysts, triethylenediamine is preferred from the viewpoint of particularly promoting the urethane reaction.
Examples of isocyanurate catalyst include: metal oxides, e.g. Li 2 O and (Bu) 3 Sn) 2 O; hydrides, e.g. NaBH 4 The method comprises the steps of carrying out a first treatment on the surface of the Alkoxide compounds, naOCH 3 KO- (t-Bu) and borates; amine compounds, e.g. N (C) 2 H 5 ) 3 、N(CH 3 ) 2 CH 2 C 2 H 5 And 1, 4-ethylenepiperazine (DABCO); basic carboxylate compounds, e.g. HCOONa, na 2 CO 3 、PhCOONa/DMF、CH 3 COOK、(CH 3 COO) 2 Ca. Alkaline soaps and naphthenates; a basic formate compound; and quaternary ammonium salt compounds, e.g., ((R) 3 -NR 'OH) -OCOR'. In addition, as a catalyst combination (cocatalyst) For example, amine/epoxide, amine/carboxylic acid, and amine/alkylene imide are given. These isocyanurate catalyst and combination catalyst may be used alone or as a mixture thereof.
Among catalysts for urethane synthesis, N' -trimethylaminoethylethanolamine (hereinafter referred to as "ETA") is preferable, which functions as a urethane catalyst alone, and also exhibits the function of an isocyanurate catalyst.
In the method of producing a polyurethane elastomer according to the present disclosure, a chain extender (multifunctional low molecular weight polyol) may be used as needed. The chain extender is, for example, a diol having a number average molecular weight of 1,000 or less. Examples of diols include: ethylene Glycol (EG), diethylene glycol (DEG), propylene Glycol (PG), dipropylene glycol (DPG), 1, 4-butanediol (1, 4-BD), 1, 6-hexanediol (1, 6-HD), 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, xylenediol (terephthalyl alcohol), and triethylene glycol. The chain extender other than the diol is, for example, a polyol having 3 or more members. Examples of the 3-membered or more polyhydric alcohol include trimethylolpropane, glycerol, pentaerythritol and sorbitol. These alcohols may be used alone or as a mixture thereof.
In addition, additives such as a conductive agent, a pigment, a plasticizer, a water repellent agent, an antioxidant, an ultraviolet absorber, and a light stabilizer may be added together as needed.
Examples (example)
Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.
< materials used >
The materials used in the examples and comparative examples are listed below.
[ polyol ]
A-1: polyether glycol (polypropylene glycol) [ product name: PREMINOL S4013F, R 2 Carbon number=3 (branching), mn=12,000, hydroxyl number: 9.4mgKOH/g, AGC Inc]
A-2: polyether glycol (polypropylene glycol) [ product name: UNOL D-2000, R 2 Carbon number=3 (branching), mn=2,000, hydroxyl number: 55.0mgKOH/g of the aqueous solution,NOF Corporation manufactured by]
A-3: polyether glycol (copolymer of tetrahydrofuran and 3-methyltetrahydrofuran) [ product name: PTG-L3000, R 2 Carbon number=5 (branched) +4 (linear), mn=2,900, hydroxyl number: 38.6mgKOH/g, hodogaya Chemical Co., ltd.)]
A-4: polyether glycol (polytetramethylene glycol) [ product name: PTMG2000, R 2 Carbon number=4 (straight chain), mn=2.000, hydroxyl number: 57.2mgKOH/g, mitsubishi Chemical Corporation production]
A-5: polycarbonate diol [ product name: kuraray Polyol C-2090, R 1 Is produced by ltd. having carbon number=6 (straight chain) +6 (branched), mn=2,000, kuraray co]
A-6: polycarbonate diol [ product name: kuraray Polyol C-2065N, R 1 Carbon number=9 (straight chain) +6 (branched), mn=2.000 (hydroxyl number: 56.4mgKOH/g, manufactured by Kuraray co., ltd.)]
A-7: polycarbonate diol [ product name: DURANOL T6002, R 1 Carbon number=6 (straight chain), mn=1.900, hydroxyl number: 57.6mgKOH/g, asahi Kasei Chemicals Corporation production]
A-8[ product name: DURANOL G3452, mn=2.1×10 3 (hydroxyl value: 53.6 mgKOH/g), asahi Kasei Chemicals Corporation production]
A-9: polyester diol [ product name: kuraray Polyol P-2050, mn=1,900, hydroxyl number: 58.1mgKOH/g, kuraray Co., ltd. ]
[ polyisocyanates ]
B-1: xylylene diisocyanate [ Tokyo Chemical Industry Co., ltd. ]
B-2: polymeric MDI [ product name: MILLIONATE MR-200 manufactured by Tosoh Corporation ]
B-3: isocyanurate compound [ product name: STABiO D-370N,Mitsui Chemicals,Inc, manufacturing ]
[ curing catalyst ]
C-1:1, 4-diazabicyclo [2.2.2] octane-2-methanol (product name; RZETA) [ Tosoh Corporation Co., ltd.)
[ chain extender ]
D-1:1, 4-butanediol
< evaluation >
The evaluation methods in examples and comparative examples are as follows.
[ evaluation 1: appearance inspection
In the polyurethane elastomer containing the matrix phase and the domain phase, the transparency tends to be lowered due to scattering of visible light, and thus the sample having a thickness of 2mm was evaluated based on the following criteria.
Evaluation criteria
Class a: opaque (no object visible through the sample)
B level: semitransparent (objects can be seen through the sample but transparency is not high)
C level: transparent (objects can be seen clearly through the sample)
[ evaluation 2: tan delta peak temperature of glass transition ]
The measurement was performed as described below using a viscoelasticity measuring device (product name: physica MCR302, manufactured by Anton Paar Japan K.K.). Test pieces having a thickness of 2mm and a width of 5mm formed with a die cutter were set, and their viscoelasticity was measured at a frequency of 1Hz from-85℃to 20℃at a temperature rising rate of 2℃per minute in a torsion mode (twist) of 20mm length, thereby providing a temperature-tan delta curve.
[ evaluation 3: micro rubber hardness ]
Microrubber hardness of a test piece having a thickness of 2mm at 23℃was measured using a microrubber hardness meter (product name: MD-1capa;Kobunshi Keiki Co, manufactured by Ltd., push-pin: A type (cylindrical shape, diameter: 0.16mm, height: 0.5mm, outer diameter: 4mm, inner diameter: 1.5mm, measurement mode: peak hold mode). The micro rubber hardness was evaluated based on the following criteria.
Evaluation criteria
Class a: the hardness of the micro rubber is less than 40 DEG
B level: the micro rubber hardness is more than 40 DEG and less than 50 DEG
C level: the micro rubber hardness is above 50 DEG
[ evaluation 4: friction Properties (evaluation 4-1: dynamic Friction coefficient/evaluation 4-2: abrasion resistance) ]
The evaluation was performed using a ball and disc type friction abrasion tester (product name: HEIDON type: 20,Shinto ScientificCo, manufactured by ltd.) as follows. A SUS ball indenter (diameter: 10 mm) was pressed against a test piece having a thickness of 2mm fixed with a double-sided tape under a constant load, and rotated and slid. Therefore, the friction properties of the test piece having a thickness of 2mm at a temperature of 23℃were evaluated under the following measurement conditions.
Load: 0.5N (50 g)
Diameter of rotation: 1cm
Rotational speed: 192rpm (10 cm/second)
Measurement time: 300 seconds
< evaluation 4-1> the coefficient of dynamic friction was calculated as the average value of the measured values after 10 seconds to 300 seconds (sampling speed: 5 ms) from the start of measurement, and evaluation was made based on the following criteria.
Evaluation criteria
Class a: coefficient of dynamic friction less than 1.6
B level: a dynamic friction coefficient of 1.6 or more and less than 2.4
C level: the dynamic friction coefficient is more than 2.4
< evaluation 4-2> abrasion resistance was evaluated from the result of visual observation of abrasion marks after measuring the dynamic friction coefficient based on the following criteria.
Evaluation criteria
Class a: no abrasion trace was confirmed.
B level: the abrasion trace can be slightly confirmed.
C level: the abrasion trace can be clearly confirmed.
[ evaluation 5: elastic deformation Power (Elastic Deformation Power) (ηiT)
The elastic deformation power (. Eta.iT) at a temperature of 23℃was used as an index for evaluating compression set. ηit was measured under the following measurement conditions using a nanoindenter (manufactured by FISCHERSCOPE HM2000, fischer Instruments k.k.) by using a tetragonal cone-type vickers indenter having a face angle of 136 ° as an indenter.
Maximum indentation load: 10mN
Load speed: 10mN/30 seconds
Maximum load hold time: 60 seconds
Unloading time: 5 seconds
From the resulting "load-displacement curve", ηit is calculated by using the following formula.
ηit (%) = (elastic deformation work/total deformation work) ×100
From the obtained ηit, compression set was evaluated based on the following criteria.
Evaluation criteria
Class a: eta iT is 80% or more
B level: eta iT is more than 60% and less than 80%
C level: eta iT is less than 60%
[ evaluation 6: average diameter of regional phase in section of polyurethane elastomer and area ratio of matrix phase to regional phase ]
The cross section of the polyurethane elastomer was observed using a Scanning Probe Microscope (SPM) (product name: S-Image, manufactured by Hitachi High-Tech Science Corporation) under the following conditions by using a slice having a thickness of about 800nm manufactured by using a cryomicrotome (cryomicrotome).
Measurement mode: VE-DFM (viscoelastic dynamic force mode)
Cantilever: SI-DF3 (spring constant=1.9N/m)
Scan area: 50 μm square
Operating frequency: 0.3Hz to 0.5Hz
The average diameter of the regional phase and the area ratio of the matrix phase to the regional phase were determined by detecting the regional phase region using a grain analysis module using SPM Image analysis software SPIP (Scanning Probe Image Processor, manufactured by Image technology).
[ evaluation 7: identification and analysis of matrix phase and regional phase in section of polyurethane elastomer (examples 1 to 12)
Mapping was performed on a cut piece made of a sheet-like polyurethane elastomer having a thickness of 2mm by using a microtome using a three-dimensional microscopic laser Raman spectrum analyzer (product name: nanofinder 30,Tokyo Instruments,Inc. Manufactured)And (5) measuring. The measurement mode was EM, and 60X 60 points were measured at 500nm intervals to provide 0cm -1 To 400cm -1 Is a whole image of the image. From the obtained integral image, a matrix phase and a plurality of domain phases dispersed in the matrix phase were confirmed in the sheet. In addition, the matrix phase and the domain phase are clearly phase separated.
Then, raman spectra of portions of the matrix phase and the region phase are measured from the integrated image. The measurement was performed under the following conditions: the light source is Nd-YVO 4 (wavelength: 532 nm), laser intensity was 240. Mu.W, objective magnification was 100 times, diffraction grating was 300gr/mm, pinhole diameter was 100 μm, exposure time was 30 seconds, and number of scans was 1. From the obtained raman spectrum, it was confirmed that the matrix phase had a structure derived from polycarbonate polyurethane, and the domain phase had a structure derived from polyether polyol.
Example 1
< preparation of urethane prepolymer UP1 >
31.9 parts by mass of polyol A-1, 1.0 parts by mass of polyisocyanate B-1 and 500ppm of curing catalyst C-1 were uniformly mixed, and the mixture was heated at a temperature of 100℃for 24 hours to synthesize a polyol having isocyanate groups at the terminal thereof. 59.2 parts by mass of polyol A-5 was mixed into the polyol, and the mixture was heated at a temperature of 100℃for 4 hours to prepare a urethane prepolymer UP1.
< Synthesis of polyurethane elastomer No.1 >
92.1 parts by mass of urethane prepolymer UP1, 1.7 parts by mass of B-1, 2.5 parts by mass of B-2 and 3.7 parts by mass of B-3 were mixed, and the mixture was stirred for 2 minutes with a autorotation revolution type vacuum stirring defoaming mixer (product name: V-mini300, manufactured by EME Inc.) at a revolution speed of 1600rpm until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture according to the present embodiment was obtained. Next, the polyurethane elastomer-forming mixture was preheated to a temperature of 130 ℃, poured into a mold on which a mold release agent was thinly coated to produce a sheet having a thickness of 2mm, and cured by heating at a temperature of 130 ℃ for 2 hours. Next, the cured product was taken out of the mold and post-cured at a temperature of 80℃for 2 days to obtain a sheet-like polyurethane elastomer No.1 having a thickness of 2 mm.
Example 2
< preparation of urethane prepolymer UP2 >
13.5 parts by mass of polyol A-1, 26.9 parts by mass of polyol A-2, 4.0 parts by mass of polyisocyanate B-1 and 500ppm of curing catalyst C-1 were uniformly mixed, and the mixture was heated at a temperature of 100℃for 24 hours to synthesize a polyol having an isocyanate group at the terminal thereof. 49.4 parts by mass of polyol A-5 was mixed in the polyol, and the mixture was heated at a temperature of 100℃for 4 hours to produce urethane prepolymer UP2.
< Synthesis of polyurethane elastomer No.2 >
93.8 parts by mass of urethane prepolymer UP2, 2.5 parts by mass of B-2 and 3.7 parts by mass of B-3 were mixed, and the mixture was stirred for 2 minutes with a autorotation revolution type vacuum stirring defoaming mixer at a revolution speed of 1600rpm until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, a polyurethane elastomer No.2 was obtained in the same manner as in example 1 except that the polyurethane elastomer-forming mixture was used.
Example 3
< preparation of urethane prepolymer UP3 >
35.6 parts by mass of polyol A-2, 4.9 parts by mass of polyisocyanate B-1 and 500ppm of curing catalyst C-1 were uniformly mixed, and the mixture was heated at a temperature of 100℃for 24 hours to synthesize a polyol having isocyanate groups at the terminal thereof. 53.3 parts by mass of polyol A-5 was mixed in the polyol, and the mixture was heated at a temperature of 100℃for 4 hours to produce urethane prepolymer UP3.
< Synthesis of polyurethane elastomer No.3 >
93.8 parts by mass of urethane prepolymer UP3, 2.5 parts by mass of B-2 and 3.7 parts by mass of B-3 were mixed, and the mixture was stirred for 2 minutes with a autorotation revolution type vacuum stirring defoaming mixer at a revolution speed of 1600rpm until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, polyurethane elastomer No.3 was obtained in the same manner as in example 1 except that the polyurethane elastomer-forming mixture was used.
Example 4
< preparation of urethane prepolymer UP4 >
18.0 parts by mass of polyol A-1, 0.6 parts by mass of polyisocyanate B-1 and 500ppm of curing catalyst C-1 were uniformly mixed, and the mixture was heated at a temperature of 100℃for 24 hours to synthesize a polyol having isocyanate groups at the terminal thereof. 72.1 parts by mass of polyol A-5 was mixed in the polyol, and the mixture was heated at a temperature of 100℃for 4 hours to produce urethane prepolymer UP4.
< Synthesis of polyurethane elastomer No.4 >
93.7 parts by mass of the urethane prepolymer, 3.1 parts by mass of B-1, 2.5 parts by mass of B-2 and 3.7 parts by mass of B-3 were mixed, and the mixture was stirred with a autorotation revolution type vacuum stirring defoaming mixer (product name: V-mini300 manufactured by EME Inc.) at revolution speed of 1,600rpm for 2 minutes until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, a polyurethane elastomer No.4 was obtained in the same manner as in example 1 except that the polyurethane elastomer-forming mixture was used.
Example 5
A urethane prepolymer UP5 was produced in the same manner as in example 1, except that polyol a-6 was used instead of polyol a-5. In addition, polyurethane elastomer No.5 was obtained in the same manner as in example 1 except that urethane prepolymer UP5 was used.
Example 6
A urethane prepolymer UP6 was produced in the same manner as in example 1, except that polyol a-7 was used instead of polyol a-5. Further, polyurethane elastomer No.6 was obtained in the same manner as in example 1 except that urethane prepolymer UP6 was used.
Example 7
A urethane prepolymer UP7 was produced in the same manner as in example 1, except that polyol a-8 was used instead of polyol a-5. In addition, polyurethane elastomer No.7 was obtained in the same manner as in example 1 except that urethane prepolymer UP7 was used.
Example 8
< preparation of urethane prepolymer UP8 >
32.5 parts by mass of polyol A-1, 1.0 parts by mass of polyisocyanate B-1 and 500ppm of curing catalyst C-1 were uniformly mixed, and the mixture was heated at a temperature of 100℃for 24 hours to synthesize a polyol having isocyanate groups at the terminal thereof. 56.8 parts by mass of polyol A-5 was mixed in the polyol, and the mixture was heated at a temperature of 100℃for 4 hours to produce urethane prepolymer UP8.
< Synthesis of polyurethane elastomer No.8 >
90.2 parts by mass of urethane prepolymer UP8 and 0.8 parts by mass of D-1 were mixed. Then, 2.8 parts by mass of B-1, 2.5 parts by mass of B-2 and 3.7 parts by mass of B-3 were mixed, and the mixture was stirred with a autorotation revolution type vacuum stirring defoaming mixer (product name: V-mini300 manufactured by EME Inc.) at revolution speed of 1,600rpm for 2 minutes until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, a polyurethane elastomer No.8 was obtained in the same manner as in example 1 except that the polyurethane elastomer-forming mixture was used.
Example 9
< preparation of urethane prepolymer UP9 >
35.9 parts by mass of polyol A-3, 4.1 parts by mass of polyisocyanate B-1 and 500ppm of curing catalyst C-1 were uniformly mixed, and the mixture was heated at a temperature of 100℃for 4 hours to synthesize a polyol having isocyanate groups at the terminal thereof. 53.8 parts by mass of polyol A-5 was mixed in the polyol, and the mixture was heated and stirred at a temperature of 100℃for 4 hours to produce urethane prepolymer UP9.
< Synthesis of polyurethane elastomer No.9 >
93.8 parts by mass of urethane prepolymer UP9, 2.5 parts by mass of B-2 and 3.7 parts by mass of B-3 were mixed, and the mixture was stirred with a autorotation revolution type vacuum stirring defoaming mixer at revolution speed of 1,600rpm for 2 minutes until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, a polyurethane elastomer No.9 was obtained in the same manner as in example 1 except that the polyurethane elastomer-forming mixture was used.
Example 10
< preparation of urethane prepolymer UP10 >
35.6 parts by mass of polyol A-4, 4.9 parts by mass of polyisocyanate B-1 and 500ppm of curing catalyst C-1 were uniformly mixed, and the mixture was heated at a temperature of 100℃for 4 hours to synthesize a polyol having isocyanate groups at the terminal thereof. 53.3 parts by mass of polyol A-5 was mixed in the polyol, and the mixture was heated at a temperature of 100℃for 4 hours to produce a urethane prepolymer UP10.
< Synthesis of polyurethane elastomer No.10 >
93.8 parts by mass of urethane prepolymer UP10, 2.5 parts by mass of B-2 and 3.7 parts by mass of B-3 were mixed, and the mixture was stirred with a autorotation revolution type vacuum stirring defoaming mixer at revolution speed of 1,600rpm for 2 minutes until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, a polyurethane elastomer No.10 was obtained in the same manner as in example 1 except that the polyurethane elastomer-forming mixture was used.
Example 11
< preparation of urethane prepolymer UP11 >
31.9 parts by mass of polyol A-1, 0.3 parts by mass of polyisocyanate B-1 and 500ppm of curing catalyst C-1 were uniformly mixed, and the mixture was heated at a temperature of 100℃for 24 hours to synthesize a polyol having isocyanate groups at the terminal thereof. 59.2 parts by mass of polyol A-5 was mixed in the polyol, and the mixture was heated at a temperature of 100℃for 4 hours to produce a urethane prepolymer UP11.
< Synthesis of polyurethane elastomer No.11 >
92.1 parts by mass of urethane prepolymer UP11, 2.4 parts by mass of B-1, 2.5 parts by mass of B-2 and 3.7 parts by mass of B-3 were mixed, and the mixture was stirred for 2 minutes with a autorotation revolution type vacuum stirring defoaming mixer (product name: V-mini300, manufactured by EME Inc.) at revolution speed of 1,600rpm until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, a polyurethane elastomer No.11 was obtained in the same manner as in example 1 except that the polyurethane elastomer-forming mixture was used.
Example 12
< preparation of urethane prepolymer UP12 >
31.9 parts by mass of polyol A-1, 1.5 parts by mass of polyisocyanate B-1 and 500ppm of curing catalyst C-1 were uniformly mixed, and the mixture was heated at a temperature of 100℃for 24 hours to synthesize a polyol having isocyanate groups at the terminal thereof. 59.2 parts by mass of polyol A-5 was mixed in the polyol, and the mixture was heated at a temperature of 100℃for 4 hours to produce a urethane prepolymer UP12.
< Synthesis of polyurethane elastomer No.12 >
92.1 parts by mass of urethane prepolymer UP12, 1.2 parts by mass of B-1, 2.5 parts by mass of B-2 and 3.7 parts by mass of B-3 were mixed, and the mixture was stirred for 2 minutes with a autorotation revolution type vacuum stirring defoaming mixer (product name: V-mini300, manufactured by EME Inc.) at revolution speed of 1,600rpm until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, a polyurethane elastomer No.12 was obtained in the same manner as in example 1 except that the polyurethane elastomer-forming mixture was used.
Comparative example 1
87.7 parts by mass of polyol A-5, 4.5 parts by mass of B-1, 3.1 parts by mass of B-2, 4.7 parts by mass of B-3 and 500ppm of curing catalyst C-1 were mixed, and the mixture was stirred with a autorotation type vacuum stirring defoaming mixer at revolution speed of 1,600rpm for 2 minutes until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, a polyurethane elastomer No. c1 was obtained in the same manner as in example 1, except that the polyurethane elastomer-forming mixture was used.
Comparative example 2
35.1 parts by mass of polyol A-2, 52.6 parts by mass of polyol A-9, 4.6 parts by mass of B-1, 3.1 parts by mass of B-2, 4.7 parts by mass of B-3 and 500ppm of curing catalyst C-1 were mixed, and the mixture was stirred with a autorotation type vacuum stirring defoaming mixer at revolution speed of 1,600rpm for 2 minutes until the mixture became uniform. Thus, a polyurethane elastomer-forming mixture was obtained. Then, a polyurethane elastomer No. c2 was obtained in the same manner as in example 1, except that the polyurethane elastomer-forming mixture was used.
The evaluation results of the polyurethane elastomers according to examples 1 to 12 and comparative examples 1 and 2 are shown in tables 1 to 1 (examples) and tables 1 to 2 (comparative examples).
[ Table 1-1]
[ tables 1-2]
< Structure of polyurethane elastomer >
Typical temperature-tan delta curves (example 1, comparative examples 1 and 2) obtained by viscoelastic measurement among the results shown in tables 1-1 and 1-2 are shown in fig. 2. As shown in fig. 2, in example 1, 2 tan delta peak temperatures (glass transition temperatures) were confirmed in the range of-80 ℃ to 10 ℃, whereas in comparative examples 1 and 2, only 1 peak temperature was confirmed. In addition, regarding the appearance of the polyurethane elastomers, the polyurethane elastomers nos. 1 to 12 according to examples 1 to 12 were opaque. On the other hand, the polyurethane elastomers No. c1 and No. c2 according to comparative examples 1 and 2 have high transparency.
The tan delta peak temperatures observed in the polyurethane elastomer No.1 according to example 1 were-65℃and-22℃and were glass transition temperatures corresponding to the polyether polyurethane derived from the raw material A-1 (polypropylene glycol) and the polycarbonate polyurethane derived from the raw material A-3 (polycarbonate polyol), respectively (see comparative example 1). That is, it is clear that in the polyurethane elastomer No.1 obtained in example 1, the polyurethane containing polycarbonate and the polyurethane containing polyether are hardly compatible with each other but exist in a clear phase-separated manner. In addition, a clear phase separation structure between the domain phase and the matrix phase was observed from a viscoelastic image of a cross section of the polyurethane elastomer No.1 shown in fig. 3 taken with a viscoelastic atomic force microscope (VE-AFM). In addition, it is shown that the region phase with high black concentration in the viscoelastic image is derived from the ether structure with low hardness in the polyurethane elastomer (formula (2)), and the matrix phase with low black concentration is derived from the carbonate structure with high hardness in the polyurethane elastomer (formula (1)).
Likewise, in the polyurethane elastomers nos. 2 to 12 according to examples 2 to 12, in the temperature-loss tangent (tan δ) curve obtained by Dynamic Mechanical Analysis (DMA) in the same manner as in the polyurethane elastomer No.1, two peaks ascribed to glass transition were observed in the temperature range of-80 ℃ to +20 ℃. Further, clear phase separation structures between the domain phase and the matrix phase were observed from the viscoelastic images of the respective cross sections of the polyurethane elastomers nos. 2 to 12 photographed by a viscoelastic atomic force microscope (VE-AFM). In addition, it is shown that the domain phase with high black concentration in the viscoelastic image is derived from the ether structure with low hardness in the polyurethane elastomer (formula (2)), and the matrix phase with low black concentration is derived from the carbonate structure with high hardness in the polyurethane elastomer (formula (1)).
On the other hand, in the polyurethane elastomer No. c2 obtained in comparative example 2, the appearance and the cross-sectional observation result of high transparency were obtained. In addition, in addition to the foregoing, only 1 tan δ peak was observed at-53 ℃, and thus it was confirmed that the polyether polyurethane and the polyester polyurethane were substantially completely compatible with each other, and did not have a phase separation structure.
< physical Properties of polyurethane elastomer >
In the polyurethane elastomer No.1 according to example 1, the hardness was significantly reduced, and a reduction in the dynamic friction coefficient was also observed, as compared with the single polycarbonate polyurethane No. c1 obtained in comparative example 1. In addition, the polyurethane elastomer obtained in example 1 has excellent abrasion resistance and exhibits high elastic deformation power (low compression set) comparable to that of silicone elastomer.
On the other hand, in the polyurethane elastomer No. c2 obtained in comparative example 2, the hardness was low, but the abrasion resistance was low. When evaluating friction properties, ball indenters made of stainless steel (SUS 304) float and bounce due to surface roughness caused by abrasion, and thus it is difficult to measure the dynamic friction coefficient. In addition, the elastic deformation power was low as compared with examples 1 and 2, and a tendency of deterioration in compression set was observed.
As is apparent from the above results, the polyurethane elastomer according to the present disclosure exhibits excellent effects capable of achieving low hardness, excellent friction properties, and low compression set. These effects were determined to be caused by the presence of a phase separation structure in which polycarbonate polyurethane was disposed in the matrix phase and polyether polyurethane was disposed in the regio-phase.
The present disclosure is not limited to the above-described embodiments, and various changes and modifications may be made without departing from the spirit and scope of the present disclosure. The following claims are intended to disclose the scope of the present disclosure.
The present application claims priority based on Japanese patent application Nos. 2021-074333 filed on 26 4 months of 2021, 2022-011688 filed on 28 months of 2022, and 2022-043901 filed on 18 months of 2022, and is incorporated herein by reference in its entirety.
[ description of reference numerals ]
51. First polyether
52. First polycarbonate polyol
53. Urethane prepolymers
54. Liquid drop
55. Second polycarbonate polyol
56. Polyisocyanates
31. Matrix body
32. Region(s)
33. Polyurethane elastomer
Claims (9)
1. A polyurethane elastomer characterized in that it comprises:
a first repeating structural unit represented by the general formula (1); and
a second repeating structural unit represented by the general formula (2),
the polyurethane elastomer includes a matrix phase and a domain phase dispersed in the matrix phase,
the matrix phase comprising the first repeating structural unit, and
the domain phase comprises the second repeat unit:
[ chemical formula 1]
Wherein R is 1 Represents an alkylene group having 3 to 12 carbon atoms;
[ chemical formula 2]
Wherein R is 2 Represents an alkylene group having 3 to 6 carbon atoms.
2. The polyurethane elastomer according to claim 1, wherein in a temperature-loss tangent (tan δ) curve obtained by Dynamic Mechanical Analysis (DMA) of the polyurethane elastomer, there are at least two peaks ascribed to glass transition observed in a temperature range of-80 ℃ to +20 ℃.
3. The polyurethane elastomer according to claim 1 or 2, wherein at least one of the peaks ascribed to glass transition is observed in a temperature range below-50 ℃ and at least one is observed in a temperature range above-40 ℃.
4. A polyurethane elastomer according to any one of claims 1 to 3, wherein at least 1 of the peaks ascribed to glass transition are observed in a temperature range below-60 ℃ and at least 1 are observed in a temperature range above-35 ℃.
5. The polyurethane elastomer according to any one of claims 1 to 4, wherein the area ratio of the matrix phase/the domain phase is 40/60 to 90/10.
6. The polyurethane elastomer according to any one of claims 1 to 5, wherein the average diameter of the domain phase is in the range of 0.2 to 30 μm.
7. The polyurethane elastomer according to any one of claims 1 to 6, wherein R in the first repeating structural unit 1 Represents an alkylene group having 3 to 9 carbon atoms.
8. The polyurethane elastomer according to any one of claims 1 to 7, wherein R in the second repeating structural unit 2 Represents an alkylene group containing a branched structure having 3 to 5 carbon atoms.
9. A method for producing a polyurethane elastomer, characterized in that the polyurethane elastomer is a polyurethane elastomer according to any one of claims 1 to 8, comprising the steps of:
(i) Reacting a first polyether having at least one isocyanate group and a first polycarbonate polyol having at least two hydroxyl groups with each other to provide a urethane prepolymer having at least two hydroxyl groups;
(ii) Providing a dispersion in which droplets containing at least a portion of the urethane prepolymer are dispersed in a second polycarbonate polyol; and
(iii) Preparing a polyurethane elastomer-forming mixture containing the dispersion and a polyisocyanate having at least two isocyanate groups, and then
Reacting the urethane prepolymer, the second polycarbonate polyol, and the polyisocyanate in the polyurethane elastomer forming mixture with one another to form a polyurethane elastomer.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2021-074333 | 2021-04-26 | ||
| JP2022-011868 | 2022-01-28 | ||
| JP2022043901A JP2022168829A (en) | 2021-04-26 | 2022-03-18 | Polyurethane elastomer and production method thereof |
| JP2022-043901 | 2022-03-18 | ||
| PCT/JP2022/016102 WO2022230584A1 (en) | 2021-04-26 | 2022-03-30 | Polyurethane elastomer and production method therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117203257A true CN117203257A (en) | 2023-12-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202280031232.6A Pending CN117203257A (en) | 2021-04-26 | 2022-03-30 | Polyurethane elastomer and method for producing same |
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| Country | Link |
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| CN (1) | CN117203257A (en) |
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