High-Performance Polyurethane Elastomer

Abstract

The present disclosure provides (i) a compound of formula I: [Formula 1] JPEG2025542144000010.jpg22170 an aminobenzoate diamine chain extender of (ii) a polyurethane elastomer that is the reaction product of a polyester polyol, (iii) 1,4 butanediol, and (iv) 4,4'-methylenediphenyl diisocyanate.

Description

[Technical Field]

[0001] Embodiments of the present disclosure are directed to elastomers, specifically polyurethane elastomers. [Background technology]

[0002] The benchmark technology for high-performance polyurethane elastomers is toluene diisocyanate (TDI) / 4,4'-methylenebis(2-chloroaniline), also known as TDI / MbOCA or TDI / MOCA. However, this composition is hazardous and has regulatory implications associated with its use. There are also concerns about the high energy consumption associated with the high temperatures required to process TDI / MbOCA systems. As a result, customers have attempted to switch from TDI / MbOCA to less hazardous and more sustainable MDI / glycol-based systems to produce elastomers suitable for applications requiring tough, resilient, high-performance polyurethane elastomers. Such applications include cardboard cutting anvils, wheels, rollers, and gaskets, among other technical articles. However, diphenylmethane diisocyanate (MDI) / glycol-based systems take a long time to cure, which increases demold times to unsatisfactory levels. MDI technology is also more sensitive to processing conditions such as mixing, mix ratio, and temperature. Air bubbles or shrinkage marks are also common defects that MDI technology proves more difficult to control in some applications, including those that require parts to be cast in closed or open molds, such as cardboard cutting anvils or grading screens.

[0003] As a result, there is a need in the art for PU engineering elastomer formulations that can provide improved processing and mechanical properties that are valuable in certain applications such as cardboard cutting anvils. Summary of the Invention

[0004] The present disclosure provides a process for improving PU engineering elastomer formulations that can provide improved processing and mechanical properties valuable in certain applications, such as cardboard cutting anvils, gaskets, wheels, rollers, and other articles that would benefit from the disclosed PU engineering elastomer formulations. Specifically, the present disclosure provides multi-component polyurethane systems with improved cure profiles combined with high levels of mechanical properties and improved aesthetics. Embodiments of the present disclosure incorporate an aminobenzoate compound into the polyurethane elastomer reaction mixture extended with 1,4-butanediol in a predetermined ratio that helps improve the cure profile while maintaining desired mechanical properties. Embodiments of the present disclosure also lower processing temperatures, potentially reducing or eliminating energy-intensive post-cure steps.

[0005] For various embodiments, the present disclosure provides a composition comprising (i) 2 to 15 weight percent (wt %) of a compound of Formula I:

[0006] [ka] (ii) 50-60 wt % of a polyester polyol having a Mw of 500-4000 g / mol, (iii) 2-12 wt % of 1,4 butanediol, and (iv) 24-36 wt % of 4,4'-methylenediphenyl diisocyanate. For various embodiments, the aminobenzoate diamine chain extender has a weight ratio to the 1,4 butanediol (aminobenzoate diamine chain extender:1,4 butanediol) of 0.8:1 to 2.0:1, and the weight percentages of (i)-(iv) are based on the total weight of (i)-(iv), with the total weight of (i)-(iv) not exceeding 100%. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present disclosure provides a process for improving PU engineering elastomer formulations that can provide improved processing and mechanical properties valuable in certain applications, such as cardboard cutting anvils, gaskets, wheels, rollers, and other articles that would benefit from the disclosed PU engineering elastomer formulations. Specifically, the present disclosure provides multi-component polyurethane systems with improved cure profiles combined with high levels of mechanical properties and improved aesthetics. Embodiments of the present disclosure incorporate an aminobenzoate compound into the polyurethane elastomer reaction mixture extended with 1,4-butanediol in a predetermined ratio that helps improve the cure profile while maintaining desired mechanical properties. Embodiments of the present disclosure also lower processing temperatures, potentially reducing or eliminating energy-intensive post-cure steps.

[0008] For various embodiments, the present disclosure provides a composition comprising (i) 2 to 15 weight percent (wt %) of a compound of Formula I:

[0009] [ka] (ii) 50-60 wt % of a polyester polyol having a Mw of 500-4000 g / mol, (iii) 2-12 wt % of 1,4 butanediol, and (iv) 24-36 wt % of 4,4'-methylenediphenyl diisocyanate. For various embodiments, the aminobenzoate diamine chain extender has a weight ratio to the 1,4 butanediol (aminobenzoate diamine chain extender:1,4 butanediol) of 0.8:1 to 2.0:1, and the weight percentages of (i)-(iv) are based on the total weight of (i)-(iv), with the total weight of (i)-(iv) not exceeding 100%.

[0010] (i) Aminobenzoate diamine chain extenders For various embodiments, the polyurethane elastomer comprises (i) 2 to 15 weight percent of a polyurethane elastomer represented by Formula I:

[0011] [ka] where n is greater than 2 and less than 4. For various embodiments, the polyurethane elastomer may be formed via the reaction product with (i) 5 to 12 weight percent of an aminobenzoate diamine chain extender of Formula I. For various embodiments, n may also range from 3 to 4. Other preferred values ​​of n include the range from 3.3 to 3.7, with a value of 3.5 being preferred.

[0012] (ii) Polyester polyol For various embodiments, the polyurethane elastomer is formed via the reaction product of (ii) 50-60 wt % of a polyester polyol having a Mw of 500-4000 g / mol. For various embodiments, the polyurethane elastomer can be formed via the reaction product of (ii) 53-58 wt % of a polyester polyol. For various embodiments, the polyester polyol is a poly(ethylene adipate) polyester polyol. The poly(ethylene adipate) polyester polyol can have the structure of Formula II:

[0013] [ka] where n can be a real number from 2.5 to 25. Preferably, the poly(ethylene adipate) polyester polyol has a Mw of 1000 to 3000 g / mol, with 2000 g / mol being a preferred value. The functionality of the poly(ethylene adipate) polyester polyol can be a value of 2.

[0014] The poly(ethylene adipate) polyester polyols of the present disclosure can be formed from the polycondensation reaction of monoethylene glycol and adipic acid (dimethyl adipate), as is known in the art.

[0015] (iii) 1,4 butanediol For various embodiments, the polyurethane elastomer is formed via the reaction product of (iii) 2 to 12 weight percent 1,4 butanediol. For various embodiments, the polyurethane elastomer can be formed via the reaction product of (iii) 4 to 9 weight percent 1,4 butanediol.

[0016] (iv) 4,4'-methylenediphenyl diisocyanate For various embodiments, the polyurethane elastomer is formed via the reaction product with (iv) 24 to 36 weight percent 4,4'-methylene diphenyl diisocyanate. For various embodiments, the polyurethane elastomer can be formed via the reaction product with (iv) 28 to 32 weight percent 4,4'-methylene diphenyl diisocyanate (4,4'-MDI). For various embodiments, the 4,4'-MDI can be pure 4,4'-MDI (100 weight percent 4,4'-MDI). Alternatively, the 4,4'-MDI of the present disclosure may contain small amounts of other MDI isomers. For example, a 4,4'-MDI suitable for the present disclosure may contain up to 2 weight percent 2,4'-MDI (e.g., 98 weight percent 4,4'-MDI and 2 weight percent 2,4'-MDI). 4,4'-MDI suitable for the present disclosure may contain up to 5% by weight of 2,4'-MDI (eg, 98% by weight 4,4'-MDI and 5% by weight 2,4'-MDI).

[0017] For various embodiments, the aminobenzoate diamine chain extender of Formula I may be premixed with the poly(ethylene adipate) polyester polyol prior to reaction to form the polyurethane elastomer. Such premixing can provide benefits from a processing standpoint, including: (a) the premixing helps lower the freezing temperature of the poly(ethylene adipate) polyester polyol, thereby allowing the polyurethane elastomer to be formed at lower than typical processing temperatures (e.g., reactants (i)-(iv) can be processed at 50°C rather than the 70°C typically required for poly(ethylene adipate) polyester polyol). As one skilled in the art will appreciate, practical processing temperatures are typically significantly higher than the freezing point to reduce the risk of material freezing in the "cold spots" of the dispenser, thereby causing blockages. Furthermore, premixing the aminobenzoate diamine chain extender of Formula I with the poly(ethylene adipate) polyester polyol prior to reaction to form the polyurethane elastomer reduces the number of feed lines in the mixing and dispensing system, thereby enabling the polyurethane elastomer to be formed in a typical three-component dispenser. In such a three-component system, the polyurethane elastomer can be formed by mixing (a) 1,4-butanediol, (b) premixed aminobenzoate diamine chain extender of Formula I and poly(ethylene adipate) polyester polyol, and (c) polyurethane prepolymer provided herein through separate lines (a)-(c). Other mixing options are also available, as known in the art.

[0018] Polyurethane Prepolymer In various embodiments, prior to forming the reaction product of (i)-(iv) to produce the polyurethane elastomer of the present disclosure, (iv) 4,4'-MDI can first be reacted with (ii) a polyester polyol as provided herein to form a polyurethane prepolymer. For various embodiments, the polyurethane prepolymer is the reaction product of all of the (iv) 4,4'-MDI used in forming the polyurethane elastomer with (i)-(iv) and less than all of the (ii) polyester polyol used in the reaction to form the polyurethane elastomer. For example, a polyurethane prepolymer can be the reaction product of 100% by weight of (iv) 4,4'-methylenediphenyl diisocyanate used in the reaction to form the polyurethane elastomer (e.g., all 100% by weight of the 24 to 36% by weight of 4,4'-MDI used in forming the polyurethane elastomer using (i) to (iv)) and 90 to 99% by weight of (ii) polyester polyol used in the reaction to form the polyurethane elastomer (e.g., less than all of the (ii) polyester polyol used in the reaction to form the polyurethane elastomer using (i) to (iv)). In this approach, line (b) of the three-component system described above includes a premixed aminobenzoate diamine chain extender of Formula I and the remainder of the poly(ethylene adipate) polyester polyol not used in forming the polyurethane prepolymer provided in line (c). This approach also allows polyurethane elastomers of different hardness grades to be obtained by adjusting the weight percent of (ii) polyester polyol used in forming the polyurethane prepolymer.

[0019] In additional embodiments, prior to forming the reaction product of (i)-(iv) to produce the polyurethane elastomer of the present disclosure, it is also possible to first react all of the (iv) 4,4'-MDI used in forming the polyurethane elastomer of the present disclosure with all of the (ii) polyester polyol to form a polyurethane prepolymer, as provided herein. Thus, for example, the polyurethane prepolymer can be the reaction product of 100% by weight of the (iv) 4,4'-methylenediphenyl diisocyanate used in the reaction to form the polyurethane elastomer (e.g., 100% by weight of all of the 24-36% by weight of 4,4'-MDI used in forming the polyurethane elastomer using (i)-(iv)) with 100% by weight of the (ii) polyester polyol used in the reaction to form the polyurethane elastomer (e.g., 100% by weight of all of the (ii) polyester polyol used in the reaction to form the polyurethane elastomer using (i)-(iv)). In this approach, line (a) may contain 1,4-butanediol, line (b) may contain the aminobenzoate diamine chain extender of formula I, and line (c) may contain a polyurethane prepolymer comprising the reaction product of all of the poly(ethylene adipate) polyester polyol pre-reacted with all of the 4,4'-MDI to form the polyurethane prepolymer.

[0020] For various embodiments, the resulting polyurethane prepolymers discussed herein can have an isocyanate (NCO) group content of 6 to 16 weight percent based on the total weight of the polyurethane prepolymer.

[0021] For various embodiments, the reaction between (iv) 4,4'-MDI and (ii) polyester polyol to form the polyurethane prepolymer can be carried out under vacuum or atmospheric pressure in a dry nitrogen environment at a temperature between 40 and 80°C.

[0022] As discussed herein, the present disclosure provides a composition comprising (i) 2 to 15 weight percent (wt %) of a compound of Formula I:

[0023] [ka] (ii) 50-60 wt % of a polyester polyol having a Mw of 500-4000 g / mol, (iii) 2-12 wt % of 1,4 butanediol, and (iv) 24-36 wt % of 4,4'-MDI. For various embodiments, the aminobenzoate diamine chain extender has a weight ratio to the 1,4 butanediol (aminobenzoate diamine chain extender:1,4 butanediol) of 0.8:1 to 2.0:1, and the weight percentages of (i)-(iv) are based on the total weight of (i)-(iv), with the total weight of (i)-(iv) not exceeding 100%. In a further embodiment, the present disclosure provides a polyurethane elastomer that is the reaction product of (i) 5 to 12 weight percent of an aminobenzoate diamine chain extender of Formula I; (ii) 53 to 58 weight percent of a polyester polyol; (iii) 4 to 9 weight percent of 1,4 butanediol; and (iv) 28 to 32 weight percent of 4,4'-MDI, wherein the aminobenzoate diamine chain extender has a weight ratio to the 1,4 butanediol of 0.9:1 to 1.75:1, and the weight percents of (i) through (iv) are based on the total weight of (i) through (iv), and the total weight of (i) through (iv) does not exceed 100% of the polyurethane elastomer. In another embodiment, the present disclosure provides a polyurethane elastomer that is the reaction product of (i) 6 to 10 weight percent of an aminobenzoate diamine chain extender of Formula I, (ii) 54 to 57 weight percent of a polyester polyol, (iii) 5.5 to 7 weight percent of 1,4 butanediol, and (iv) 29 to 31 weight percent of 4,4'-MDI, wherein the aminobenzoate diamine chain extender has a weight ratio to 1,4 butanediol of 0.95:1 to 1.65:1, and the weight percents of (i) through (iv) are based on the total weight of (i) through (iv), and the total weight of (i) through (iv) does not exceed 100%. For various embodiments, the polyurethane elastomer is not formed using either toluene diisocyanate or 4,4'-methylenebis(2-chloroaniline).

[0024] Polyurethane Elastomer Reaction For various embodiments, the reaction to form the polyurethane elastomer of the present disclosure can include the following conditions: The mixing of the components in the reaction to form the polyurethane elastomer can be carried out in a dynamic polyurethane dispensing machine known in the art. Preferably, the dynamic polyurethane dispensing machine is a low-pressure dynamic polyurethane dispensing machine known in the art. The mixing of the components can be carried out in the mixing head of the polyurethane dispensing machine, in which case two or more feed lines containing the components (e.g., three lines (a)-(c)) can be mixed before dispensing the polyurethane reactive mixture. The reactive mixture can be dispensed as a spray or poured from equipment known in the art.

[0025] Reaction conditions for forming the polyurethane elastomers of the present disclosure may include preheating each of the components in the reaction system. For example, in the case of a low-pressure dispenser, processing conditions may include feeding a polyurethane prepolymer provided herein at a temperature of 50-70°C, an aminobenzoate diamine chain extender of Formula I or a mixture of an aminobenzoate diamine chain extender of Formula I and a polyester polyol at a temperature of 50-70°C, and 1,4 butanediol at a temperature of 30-50°C. The reaction may occur under positive pressure (0.5-1 bar) from dry air or nitrogen. The mold temperature may be 80-120°C. The post-cure time for forming the polyurethane elastomers of the present disclosure may be 12-24 hours at a temperature of 80-100°C. Conditioning of the resulting polyurethane elastomer may be, for example, for 7 days at ambient conditions, e.g., 23±2°C and 50±5% relative humidity. [Example]

[0026] The following examples are provided for illustrative purposes only and are not intended to define or limit the embodiments in any way. In the examples (EX) and comparative examples (CE) of the present invention, various terms and designations for materials are used, including, for example, the following:

[0027] [Table 1]

[0028] test The following test procedures were used herein.

[0029] The hardness was measured in accordance with ISO 868 (unit: Shore hardness A: ShA) after 7 days of post-curing.

[0030] Pot life was measured as the time at which the mixed composition was still visually homogeneous and had a viscosity low enough to be transferred to a mold. Typically, the viscosity threshold is indicated as less than 20,000 mPas as measured by a Brookfield viscometer measured at 23°C.

[0031] Demolding time was measured as the time it took for a standard sample (cylinder with a diameter of 70 mm and a height of 15-20 mm) to be removed from the mold without causing defects such as permanent deformation, marks, or fingerprints. Sample preparation: Casting by dispenser. All components of the system were delivered by a gear pump from a preheated tank of the dispenser into the mixing chamber. The mixed composition was then transferred into a cup / container carrying the cured material and into a mold placed in a preheated oven.

[0032] Demolding tests were used in combination with hardness measurements (eg hardness after 20 minutes at 100°C and hardness after 30 minutes at 100°C) to provide an indication of minimum molding time.

[0033] The tensile strength at break in MPa was measured according to ISO 527-Type 5 (2 mm thick specimen).

[0034] The 300% modulus (MPa) was measured in accordance with ISO527.

[0035] The angular tear strength was measured according to ISO 34-Pt B, Proc. A.

[0036] Elongation at break was measured according to ISO 527.

[0037] Compression set (22 hours / 70°C) was measured according to ISO 815-1 (Part 1).

[0038] Polyurethane prepolymer synthesis Polyurethane Prepolymer 1 Polyurethane prepolymer 1 was formed by reacting 4,4'-MDI (36 wt. % based on the total weight of polyurethane prepolymer 1) with polyol 1 (64 wt. % based on the total weight of polyurethane prepolymer 1). The 4,4'-MDI was charged to a reactor heated to 45°C under an inert atmosphere (nitrogen), and the reaction was then carried out in the presence of a small amount of acidifying agent (benzoyl chloride, 200 ppm). Polyol 1 was gradually added to the 4,4'-MDI with mixing. Polyol 1 was added at a rate sufficient to remove the heat generated by the reaction. After the addition of polyol 1 was complete, the prepolymer was digested by maintaining the reaction mixture at 70°C with stirring while monitoring the isocyanate (NCO) content, according to the method described in ASTM D5155. The formation of prepolymer 1 was considered complete when the NCO content reached a target NCO value of 9.45 wt. % based on the total weight of the prepolymer.

[0039] Machine Casting The processing temperatures of the reactants were as follows: polyurethane prepolymer 1, 70°C; polyol 1, 50-70°C; and chain extender (e.g., chain extender 1 or chain extender 2, each containing chain extender 3 (BDO)) 30-50°C.

[0040] A machined low-pressure dispenser (Polytec DG 133) using three components (polyurethane prepolymer 1 + polyol 1 + chain extender) was equipped with recirculation and mass flow meters for each component. The mixing speed was 3000-5000 rpm, and the flow rate was 2-5 kg / min. For the Examples (EX) and Comparative Examples (CE), an aminobenzoate chain extender (e.g., Chain Extender 1 or Chain Extender 2) was used in combination with Chain Extender 3 (BDO).

[0041] Table 2 shows the effect of varying the weight ratio between the aminobenzoate chain extender and BDO. For example, a weight ratio of the two aminobenzoate chain extenders close to 1:1 promoted an increase in hardness after 20 and 30 minutes. This significantly improved stiffness and shortened demold time. Further increasing the amount of BDO is undesirable because it slows the cure rate and therefore increases demold time. Further increasing the amount of aminobenzoate chain extender is undesirable because it adversely affects demold time. The results of Table 2 are shown below.

[0042] CE A is a comparative example using only BDO, resulting in a demold time that is too long. By replacing BDO with aminobenzoate (see other examples in the table), the demold time is substantially faster. CE B represents an aminobenzoate / BDO combination where the ratio is too high, resulting in insufficient improvement in demolding and polymer properties. The example CE C relates to a higher Mw aminobenzoate (core Mw of 650 g / mol) that exhibits a good cure profile, longer pot life, and faster hardness buildup, but significantly worse mechanical properties, especially in terms of tensile strength at break. CE D relates to a combination of a higher Mw aminobenzoate (core Mw of 650 g / mol) with BDO at the same ratio as EX 2. CE D shows the benefit of an improved cure profile, but mechanical properties are worse compared to EX 1 and EX 2. EX1 and EX2 represent the use of the disclosed aminobenzoate chain extenders (greater than 2 and less than 4) in combination with BDO at weight ratios of the disclosed invention, resulting in both improved cure profiles and polymer properties. Table 2 below reports experiments and results relating to polymer hardness, pot life, demold time, and selected mechanical properties. In Table 2, the ratios per 100 parts polyurethane prepolymer are determined by stoichiometry and hardness targets: 0.96 (or 1.04 index) stoichiometry and 88-92 ShA hardness.

[0043] [Table 2]

Claims

1. A polyurethane elastomer, (i) 2 to 15 weight percent (wt %) of Formula I: 【Chemistry 1】 wherein n is greater than 2 and less than 4; (ii) 50 to 60 wt. % of a polyester polyol having a Mw of 500 to 4000 g / mol; (iii) 2 to 12 wt. % of 1,4 butanediol; and (iv) 24 to 36 weight percent of 4,4'-methylenediphenyl diisocyanate, wherein the aminobenzoate diamine chain extender has a weight ratio to 1,4 butanediol of from 0.8:1 to 2.0:1, and the weight percent of (i) through (iv) is based on the total weight of (i) through (iv), and the total weight of (i) through (iv) does not exceed 100%.

2. 10. The polyurethane elastomer of claim 1, wherein (iv) is first reacted with (ii) to form a polyurethane prepolymer prior to forming the reaction product of (i)-(iv).

3. The polyurethane prepolymer 100% by weight of (iv) 4,4'-methylenediphenyl diisocyanate used in the reaction to form the polyurethane elastomer; 90 to 99 weight percent of (ii) a polyester polyol used in the reaction to form the polyurethane elastomer; 3. The polyurethane elastomer of claim 2, which is the reaction product of:

4. 4. The polyurethane elastomer according to claim 2, wherein the polyurethane prepolymer has an isocyanate (NCO) group content of 6 to 16% by weight, based on the total weight of the polyurethane prepolymer.

5. The polyurethane elastomer according to any one of claims 1 to 4, wherein the polyester polyol is a poly(ethylene adipate) polyester polyol.

6. 5. The polyurethane elastomer according to any one of claims 1 to 4, wherein the polyester polyol is a poly(ethylene adipate) polyester polyol having a Mw of 1000 to 3000 g / mol.

7. The polyurethane elastomer according to any one of claims 1 to 6, wherein in formula I, n is 3 to 4.

8. The polyurethane elastomer according to any one of claims 1 to 6, wherein in formula I, n is 3.

5.

9. The polyurethane elastomer is (i) 5 to 12 wt. % of an aminobenzoate diamine chain extender of Formula I; (ii) 53 to 58 wt. % of a polyester polyol; (iii) 4 to 9 wt. % of 1,4 butanediol; and (iv) 28 to 32 weight percent of 4,4'-methylenediphenyl diisocyanate, wherein the aminobenzoate diamine chain extender has a weight ratio to 1,4 butanediol of from 0.9:1 to 1.75:1, and the weight percent of (i) through (iv) is based on the total weight of (i) through (iv), such that the total weight of (i) through (iv) does not exceed 100%.

10. The polyurethane elastomer of any one of claims 1 to 9, formed without the use of either toluene diisocyanate or 4,4'-methylenebis(2-chloroaniline).

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