WO2019038721A1 - Polyurea composition comprising hydroxyl component and methods - Google Patents

Abstract

Methods of accelerating the reaction rate of a polyurea coating composition are described comprising a) providing a polyurea coating composition comprising a first part comprising at least one polyisocyanate, and a second part comprising greater than 40 wt.-% of aspartic acid ester polyamine; and b) combining the first part and the second part to form a liquid mixture; wherein the first part, second part or liquid mixture further a hydroxyl component having sufficiently reactivity such that when the hydroxyl component is present at a concentration no greater than 5 wt.-%, the gel time is reduced by at least 50% relative to the same composition without the hydroxyl component. In one embodiment, the method is utilized for forming a coating on a surface of a pipeline is described by applying the liquid mixture to internal surfaces of the pipeline and allowing the mixture to set forming a cured coating. Polyurea coating compositions are also described.

Description

POLYUREA COMPOSITION COMPRISING HYDROXYL COMPONENT

AND METHODS BACKGROUND

Trenchless methods for structural renovation of drinking water pipelines include the pipe in pipe method, pipe bursting method, and polyethylene thin wall lining method. As described in U.S. Patent No. 7,189,429, these methods are disadvantaged by their inability to deal with multiple bends in a pipeline and the fact that lateral connection pipes to customers' premises are

disconnected and then reinstated after execution of the renovation process.

Various compositions have been described that are suitable to form a coating on the internal surface of a drinking water pipeline. See for example US 2013/0116379 and US2015/0104652.

SUMMARY

Components of polyurea coating compositions, such as polyisocyanates and especially polyamines typically contain very small concentrations of water that can accelerate the reaction resulting is fast cure rates, as evident by the gel time. However, the concentration of water is very inconsistent, which in turn can result in wide variation in the rate of cure.

By removing the water from the first and/or second part, the water is no longer a "variable" with respect to the rate of cure. By adding a specified amount of a hydroxyl component, the cure rate can be accelerated in a controlled manner, such that the cure rate is consistent for each "batch" of the two-part composition.

Polyurea compositions that contain high concentrations of aspartic acid ester polyamines often have slow cure rates, regardless of the water concentration. Adding a specified amount of a hydroxyl component to such compositions can also increase the rate of cure. In this embodiment, inclusion of a water scavenger is not required.

In one embodiment, a method of forming a coating on a surface of a pipeline is described. The method comprising the steps of: a) providing a polyurea coating composition comprising a first part comprising at least one polyisocyanate; and a second part comprising greater than 40 wt.-% of aspartic acid ester polyamine; and b) combining the first part and the second part to form a liquid mixture; wherein the first part, second part or liquid mixture further comprises a hydroxyl component having sufficiently reactivity such that when the hydroxyl component is present at a concentration no greater than 5 wt.-%, the gel time is reduced by at least 50% relative to the same composition without the hydroxyl component;

c) applying the liquid mixture to internal surfaces of the pipeline; and d) allowing the mixture to set forming a cured coating.

In another embodiment, a method of accelerating the reaction rate of a polyurea coating composition comprising: a) providing a polyurea coating composition comprising a first part comprising at least one polyisocyanate, and a second part comprising greater than 40 wt.-% of aspartic acid ester polyamine; and b) combining the first part and the second part to form a liquid mixture; wherein the first part, second part or liquid mixture further a hydroxyl component having sufficiently reactivity such that when the hydroxyl component is present at a concentration no greater than 5 wt.-%, the gel time is reduced by at least 50% relative to the same composition without the hydroxyl component.

In other embodiments, polyurea coating compositions are described comprising a) a first part comprising at least one polyisocyanate, and b) a second part comprising greater than 40 wt.-% of aspartic acid ester polyamine. In one embodiment, the first part and/or second part further comprises a hydroxyl component, as described herein. In another embodiment, the composition further comprises a third part comprising such hydroxyl component.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 depicts a perspective view of a pipe comprising a coating of a caliper of at least 5 mm.

FIG. 2 depicts a perspective view of a pipe comprising a coating not having a caliper of at least 5 mm.

DETAILED DESCRIPTION

The present invention provides a polyurea composition, typically comprising at least two- parts. In some embodiments, the polyurea composition is suitable for applying to internal pipeline surfaces so as to form an impervious lining suitable for contact with drinking water. By virtue of its rapid setting characteristics and insensitivity to moisture after curing, the composition is particularly useful as an "in-situ" applied lining for refurbishment of existing drinking water pipelines.

The first part of the two-part coating composition generally comprises at least one polyisocyanate and the second part comprises at least one polyamine. After application and curing, the coating composition comprises the reaction product of such first and second components. The reacted coating comprises urea groups (-NR-C(O)- R-). Polymers containing urea groups are often referred to as polyureas. When the two-part coating composition comprises other isocyanate reactive or amine reactive components, the reacted coating may comprise other groups as well. The coating composition may optionally comprise a filler. For example, polyurea compositions suitable for applying to internal pipeline surfaces often contain a filler in order that the composition can be applied at a caliper of at least 5 mm in a single pass.

The amount of residual water in the polyurea coating composition can vary depending on the components. Organic components typically have no greater than 1.0, 0.5, or 0.25 wt.-% of water. However, fillers may have a higher water content. The residual water content is typically no greater than 2, 1.5, or 1 wt.% of the total polyurea coating composition.

The first part, second part, or both the first and second part optionally comprise a water scavenger, otherwise known as a drying agent. Drying agents are typically grouped into three classes. A first class of drying agents reversibly react with water. This first group varies in their drying ability with the temperature, depending on the vapor pressure of the hydrate that is formed. Examples of such drying agents include for example anhydrous sodium sulfate, magnesium sulfate or calcium chloride. Anhydrous magnesium sulfate is described as forming MgSC"4 7Η₂0 below 48°C in the presence of water and thus has a fairly large capacity to reversibly react with water. However, anhydrous MgS0₄ was not found to be an effective drying agent at ambient temperature. Further, for embodiments wherein the composition is heated at the time of application, such heating can cause the hydrate to release water due to the reversibility of such reaction.

A second class of drying agents irreversibly react with water. This class of drying agents includes alkali metals, metal hydrides and calcium carbide. Such irreversible reactions

disadvantageously produce a by-product. For example, alkali metals and hydride form hydrogen gas. Further, drying agents of this class often react with hydroxyl groups in general and thus react not only with water, but also with the hydroxyl component.

A third class of drying agent are non-reactive with water (e.g., trap water), such as molecular sieves. Molecular sieves are non-reactive in general and thus are also non-reactive with the components (e.g. polyisocyanates, polyamines, hydroxyl component) of the polyurea coating composition. Molecular sieves are types of adsorbents composed of crystalline zeolites (sodium, potassium, and calcium aluminosilicates). When such crystalline zeolites are heated, water of hydration is removed, leaving holes of molecular dimensions in the crystal lattices. These holes are of uniform size and allow the passage of small molecules into the crystals, but not the passage of large ones. The pore size of these sieves can be modified (within limits) by varying the cations built into the lattices.

In some embodiments, the first part and/or second part, or liquid mixture comprises a water adsorbing molecular sieve. Type 4A sieves generally comprise crystalline sodium aluminosilicate with a pore size of about 4 angstroms. This sieve size is suitable for adsorbing water. Type 3 A sieves comprises potassium aluminosilicate with a pore size of about 3 angstroms. Type 3 A are the most selective type of molecular sieves for water adsorption. Molecular sieves are

commercially available from various suppliers. For example, a Type 3 A molecular sieve is available from Zeochem LLC, as "PURMOL 3 ST". Such material is described as having a primary crystal size of 4.6 microns and a typical particle size of 24 microns.

In some embodiments, the water adsorbing sieve has a water adsorption capacity of at least 5, 10, 15, or 20% w/w at 50% relative humidity at 20°C in 24 hours. In otherwords, 1 gram of water adsorbing sieve may absorb 0.05, 0.10, 0.15, or 0.2 grams of water at such conditions.

When the molecular sieve comprises crystalline sodium aluminosilicate and/or potassium aluminosilicate at a high level of purity (e.g. at least 95%, 96%, 97%, 98%, or 99%) the molecular sieve has a pore size of 3-4 angstroms. When the purity is less than 100%, the molecular sieve may comprise a small amount (e.g. less than 5, 4, 3, 2, or 1 wt.-%) of sieve or pores having a smaller and/or larger pore size. In this embodiment, the molecular sieve may have an average pore size greater than 2.5 or 3 angstroms (e.g. at least 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, or 3.5) and less than 5 angstroms (e.g. no greater than 4.9, 4.8, 4.7, 4.6, or 4.5). When the pore size is too small, a water molecule is too large to be adsorbed by the molecular sieve. When the pore size is too large, a water molecule can pass through the sieve. Further, when the pore size is too large, the sieve can adsorb the hydroxyl component and hinder the acceleration of the reaction rate. Thus, in favored embodiments, the molecular sieve does not adsorb the hydroxyl component.

The addition of the water adsorbing molecular sieve generally reduces the reaction rate by removing the residual water. In one example, the gel time of the polyurea composition without the drying agent, but containing residual water was about 25 seconds. The addition of molecular sieve can increase the gel time to greater than 75 seconds. Thus, the addition of the molecular sieve alone can increase the gel time by 1.5X, 2X, 2.5X, or 3X. The gel time can be determined according to the test method described in the examples. The amount of drying agent (e.g. molecular sieve) can vary depending on the amount of residual water in the first and/or second parts of the polyurea composition. The minimal amount of drying agent can be determined by adding incremental amounts of (e.g. water adsorbing molecular sieve) drying agent until the reaction rate (e.g. gel time) no longer decreases. In typical

embodiments, the amount of drying agent will be in slight excess of the minimum. The amount of drying agent is typically at least 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 wt.-% of the total coating composition. In some embodiments, the amount of drying agent is no greater than 5, 4.5, 4, 3.5, 3.0 or 2.5 wt.-% of the total coating composition.

The polyurea coating composition further comprises an (e.g. organic) component comprising one or more reactive hydroxyl groups. The hydroxyl component is typically a liquid at 25°C or at the application temperature of the polyurea coating composition. Alternatively, the hydroxyl component is a solid that is soluble with the second part.

The term "reactive" refers to a hydroxyl group that is not sterically hindered. For example, hindered phenols such as BHT (butylated hydroxytoluene, depicted below) contains a hindered hydroxyl group (e.g. hindered phenols). The reactivity of the hydroxyl group is hindered in view of the branched (e.g. C₄) alkyl substituents. As depicted in the following structure, the branched (e.g. C₄) alkyl substituents as typically bonded to adjacent carbon atoms relative to the carbon atom bonded to the hydroxyl group.

In contrast, the hydroxyl group of nonyl phenol (depicted below) is not hindered by a neighboring substituent.

nonylphenol, molecular weight 220 g/mol. The term "reactive" does not necessarily require the hydroxyl group to be reactive enough to form urethane linkages in the presence of isocyanates at the time scales that gelling occurs in polyurea reactions, as it has been shown that urethane formation can be up to Ι ,ΟΟΟΧ slower than polyurea formation using secondary aliphatic amines.

The component comprising one or more reactive hydroxyl groups typically comprises at least two, three, or four carbon atoms. When the hydroxyl component is larger than the pore size of the water adsorbing molecular sieve, the hydroxyl component is not affected by any excess molecular sieve (i.e. in an amount greater than required to adsorb residual water) that may be present in the coating composition.

In some embodiments, the hydroxyl component is an aliphatic or aromatic alcohol. Such alcohols typically having the general formula:

R¹⁴OH

wherein R¹⁴ is alkyl, aryl, alkaryl, or aryalkyl. The number of carbon atoms of R¹⁴ typically ranges from 2 to 30. In some embodiments, the number of carbon atoms is no greater than 20, 19, 18, 17, 16, or 15 carbon atoms. The alkyl group can be linear, cyclic, or branched, provided the hydroxyl group is reactive as previously described. Suitable examples include for example ethanol, 4-sec butyl phenol, and nonylphenol.

In other embodiments, the hydroxyl component is an aliphatic or aromatic polyol. In some embodiments, such polyols have the general formula:

wherein R¹⁵ is a multivalent atom (e.g. carbon or nitrogen) or an organic moiety having a valence of at least two, L is a covalent bond or divalent organic linking group, and n typically averages from 2 to 4. When R¹⁵ is an organic moiety, the number of carbon atoms of R¹⁵ typically ranges from 2 to 30, and n typically averages from 2 to 4. In some embodiments, the number of carbon atoms is no greater than 20, 19, 18, 17, 16, or 15 carbon atoms. In some embodiments, L is a covalent bond and R¹⁵ is alkylene, arylene, alkarylene, or aryalkylene. In other embodiments, L is a C1-C4 alkylene group.

Representative polyol compounds include for example 1,2 propylene glycol; 1,2,6 hexanetriol, as well as ethylene glycol and glycerol depicted as follows.

ethylene glycol, molecular weight 62 g/mol.

glycerol, molecular weight 92 g/mol.

In some embodiments, R is alkylene and L is a C1-C4 alkylene group, such as in the case of trimethylol propane.

In some embodiments, R¹⁵ is nitrogen and L is a C1-C4 alkylene group, such as in the case of triethanolamine.

In other embodiments, R¹⁵ is carbon and L is a C1-C4 alkylene group, such as in the case of pentaerythritol.

In yet other embodiments, the hydroxyl component is a polyether polyol.

In some embodiments, the polyether polyols have the same general formula as depicted above wherein L is an ether group, such a polypropylene oxide. The number of hydroxyl groups of polyether polyols, i.e. n, can range up to 7, 8, 9, or 10. For example, "CARPOL GSP-370 is reported as having a functionality of 7.

In other embodiments, linear polyether (i.e. polypropylene oxide) polyols typically have the general formula:

wherein m is typically no greater than 20 or 25. One representative example is "VORANOL 220- HON".

In some embodiments, the hydroxyl component (e.g. alcohol, polyol) is aliphatic and therefore lacks aromatic moieties.

When the hydroxyl component is a polyether polyol, the hydroxyl component can have a higher molecular weight than the previously described compounds. For example, the molecular weight can range up to 1000 or 1500 g/mol. Further, the molecular weight per hydroxyl group can range up to 500, 550, 600, 650, 700, or 750 g/per hydroxyl group.

In contrast, the previously described alcohols, and polyol compounds typically have a molecular weight per hydroxyl group of less than 500 g/per hydroxyl group. When the molecular weight per hydroxyl group is minimized, the hydroxyl component is less likely to affect any other (e.g. mechanical) properties of the polyurea. Thus, in some embodiments, the molecular weight per hydroxyl group of the hydroxyl component is less than 500, 450, 400, 350, or 300 g/hydroxyl group. In other embodiments, the molecular weight per hydroxyl group of the hydroxyl component is less than 250, 200, 150, or 100 g/hydroxyl group. The molecular weight per hydroxyl group of the hydroxyl component is typically at least 30, such as in the case of glycerol.

The amount of hydroxyl component depends of the molecular weight per hydroxyl group

(i.e. equivalent weight). For example, when 0.49 wt.-% (based on the total composition) of glycerol is added to the second part (comprising aspartic acid ester polyamine), the hydroxyl equivalents per 100 g of the second part was about 0.0160. However, 2.41 wt-% of a 4-sec- butylphenol was needed to provide the same amount of hydroxyl equivalents per 100 g (0.0160).

The amount of hydroxyl component also depends on the desired reaction rate. For example, when 0.07 wt.-% (based on the total composition) of glycerol is added to the second part

(comprising aspartic acid ester polyamine) the gel time decreased from about 240 seconds to about 175 seconds. However, for a gel time of 97 seconds, more of this hydroxyl component was be used. One of ordinary skill in the art can plot the concentration of a particular hydroxyl component as a function of gel time to control the gel time based on the concentration added.

In general, the amount of hydroxyl component is typically at least 0.05, 0.06, 0.07, 0.08 0.09, 0.10 wt.-% of the total coating composition. The amount of hydroxyl component is typically no greater than 10, 9, 8, 7, 6, or 5 wt.-% of the total coating composition.

In favored embodiments, the hydroxyl component is sufficiently reactive such that no greater than 5 wt.-% of the hydroxyl component reduces the gel time by at least 50%, 60, 70%, 80%), 90%), or greater. Thus, this statement alone is not intended to limit the concentration of hydroxyl component, but rather specify the reactivity of the hydroxyl component. For example, if the polyurea composition has a gel time of 100 seconds, the gel time is reduced to 50 seconds with no greater than 5 wt.-%> of the hydroxyl component. Preferably, the gel time is reduced by at least 50%) with no greater than 4.5, 4, 3.5, 3, 2.5, 2, 1.5 or 1 wt.-%> of the hydroxyl component based on the total composition. Reducing the gel time with the minimal amount of hydroxyl component can favorably have substantially no effect on the other (e.g. mechanical) properties of the polyurea composition, such as tensile strength.

In some embodiments, the gel time of the polyurea coating composition further comprising the hydroxyl component is less than 200, 175, 150, 125, 100, 75, or 50 second according to the Gel Time test method described in the examples. One example of a less favored hydroxyl component has the following structure, wherein Z is -CH2OH and n is 1, commercially available from Eastman Chemical as the trade designation "ABITOL E".

At a concentration of 0.86 wt.-% of the total composition, such hydroxyl component was found to have no effect on the reaction rate. At a concentration of 5 wt.-%, the gel time was reduced from 240 seconds to 145 seconds (i.e. a 40% reduction).

Without intending to be bound by theory, it is surmised that the low reactivity may be due to this compound having more than one cyclic structure. Such cyclic (e.g. hexyl) rings share a common side thereby constraining the rotation of the ring structures. These structural features result in this material having a relatively high viscosity in comparison to other materials of similar molecular weight. For example, ABITOL E is reported to have a melt viscosity of 6500 centipoise (cP) a 50°C. The viscosity of such material may reduce its mobility within the composition, thereby reducing its reactivity. In some embodiments, the organic hydroxyl component has a viscosity less than 6000, 5500, 5000, 4500, 4000, 3500, 3000, 2500, 2000, 1500, or 1000 centipoise at 50°C. Alternatively, or in combination thereof, the bulky cyclic structure and methyl substituent near the hydroxyl group may contribute to some degree of steric hindrance.

The optional (e.g. molecular sieve) water scavenger and organic hydroxyl components can be added to the polyurea composition in various manners. In typical embodiments, the polyurea coating composition is provided with the optional water scavenger(s) and the hydroxyl

component(s) contained within the first and/or second part. In other words, the polyurea coating composition is commercially available containing both the optional water scavenger(s) and the hydroxyl component(s). This may be characterized as having the optional water scavenger(s) and the hydroxyl component(s) "pre-added" to the (e.g. two-part) polyurea coating composition. In this embodiment, the reactive polyurea coating composition comprises a) a first part comprising at least one polyisocyanate, and b) a second part comprising at least one polyamine, wherein the first part and/or second part further comprises optional water scavenger(s) and hydroxyl component(s) comprising one or more reactive hydroxyl groups. More typically, the polyurea coating composition is provided with the optional water scavenger(s) and the hydroxyl component(s) contained within the second part. The first part may also optionally contain water scavenger(s). Although the hydroxyl component can be added to the first (e.g. polyisocyanate) part, doing so result in the first part has a limited shelf life.

Alternatively, the polyurea coating composition may be provided with the optional water scavenger(s) contained within the first and/or second part, but not contain the hydroxyl component(s) in the second part. The hydroxyl component(s) is added to the second part prior to combining the first and second part or during combining the first part and the second part. This may be characterized as having the optional water scavenger(s) pre-added and the hydroxyl component(s) "post-added". In this embodiment, the reactive polyurea coating composition comprises a) a first part comprising at least one polyisocyanate, and b) a second part comprising at least one polyamine, wherein the first part and/or second part further comprises water scavenger; and c) a third part comprising a hydroxyl component comprising one or more reactive hydroxyl groups.

In yet another embodiment, the polyurea coating composition is provided without the optional water scavenger(s) and without the hydroxyl component(s). Both the optional water scavenger(s) and hydroxyl component(s) are (e.g. sequentially) added to the second part prior to combining the first and second part or during combining the first part and the second part. This may be characterized as having the optional water scavenger(s) and the hydroxyl component(s) "post-added" to the (e.g. two-part) polyurea coating composition.

The reactive components such as the polyisocyanate and polyamine can be characterized based on their functionality. Functionality may be calculated by dividing the molecular weight by the equivalent weight. The equivalent weight of isocyanate end groups can be determined by titration procedures such as, for example ASTM D 2572-97. The equivalent weight of amine end groups can be determined by titration procedures such as, for example ASTM D 2074-92. In the case of polyisocyanates, the average functionality is the average number of isocyanate (-NCO) groups of a polyisocyanate. In the case of polyamines, the average functionality is the average number of amine groups of a polyamine. The functionality is typically reported by the supplier. For example, Covestro, Leverkusen, Germany, reports the average functionality of their polyisocyanates. An average functionality is often reported when the material comprises a mixture of compounds. However, when the material is substantially a single compound, the material may be reported as difunctional (e.g. diamine) or trifunctional (e.g. triamine).

The first part of the two-part coating comprises one or more polyisocyanates.

"Polyisocyanate" refers to any organic compound that has two or more reactive isocyanate

(-NCO) groups in a single molecule such as diisocyanates, triisocyanates, tetraisocyanates, etc., and mixtures thereof. Cyclic and/or linear polyisocyanate molecules may be usefully employed. The polyisocyanate(s) of the isocyanate component are preferably aliphatic. In typical embodiments, the (e.g. aliphatic) polyisocyanates are selected such that the total composition is substantially free of isocyanate monomer (e.g. less than 0.5%).

Suitable aliphatic polyisocyanates include derivatives of hexamethylene-l,6-diisocyanate;

2,2,4-trimethylhexamethylene diisocyanate; isophorone diisocyanate; and 4,4'- dicyclohexylmethane diisocyanate. Alternatively, reaction products or prepolymers of aliphatic polyisocyanates may be utilized.

The first part generally comprises at least one aliphatic polyisocyanate. Such aliphatic polyisocyanate typically comprises one or more derivatives of hexamethylene-l,6-diisocyanate

(HDI). In some embodiments, the aliphatic polyisocyanate is a derivative of isophorone diisocyanate. The aliphatic polyisocyanate may comprise an uretdione, biuret, and/or isocyanurate of HDI.

In some embodiments, the first part comprises at least one solvent-free aliphatic

polyisocyanate(s) that is substantially free of isocyanate (HDI) monomer, i.e. less than 0.5 % and more preferably no greater than 0.3 % as measured according to DIN EN ISO 10 283. Various solvent-free aliphatic polyisocyanate(s) are available. One type of HDI uretdione polyisocyanate, reported to have an isocyanate content of 21.8 and a viscosity of 150 mPa s at 23°C is available from Covestro under the trade designation "DESMODUR N 3400". Another HDI polyisocyanate is a trimer, reported to have a viscosity of about 1200 mPa s at 23°C is available from Covestro under the trade designation "DESMODUR N 3600". Such polyisocyanates typically have an isocyanate content of 20-25%. Another polyisocyanate is an aliphatic prepolymer resin comprising ether groups, based on HDI is available from Covestro under the trade designation "DESMODUR XP 2599". Yet another aliphatic HDI polyisocyanate is a trimer is available from Covestro under the trade designation "DESMODUR N3800". This material has an NCO content of 11% and a viscosity of 6,000 mPa s at 23°C. Yet another aliphatic HDI polyisocyanate is a trimer is available from Covestro under the trade designation "DESMODUR N3300". This material has an NCO content of 21.8% and a viscosity of 3,000 mPa- s at 23°C. Yet another aliphatic polyisocyanate resin based on HDI and isophorone diisocyanate is available from Covestro under the trade designation "DESMODUR XP2838". This material has an NCO content of 20% and a viscosity of

3,000 mPa s at 23°C. One type of HDI biuret polyisocyanate, is available from Covestro under the trade designation "DESMODUR N 3200" . This material has an NCO content of 20-25% and a viscosity of 2,500 mPa s at 23°C.

In some embodiments, the first part comprises a single aliphatic polyisocyanate based on hexamethylene-l,6-diisocyanate (HDI). In this embodiment, the first part may comprise 100 wt-% of a single aliphatic polyisocyanate based on hexamethylene-l,6-diisocyanate (HDI).

In some embodiments, the first part comprises a mixture of a (first) aliphatic polyisocyanate based on hexamethylene-l,6-diisocyanate (HDI) and a (second) aliphatic polyisocyanate that is a derivative of isophorone diisocyanate.

In this embodiment, the amount of first aliphatic polyisocyanate is typically at least 70, 75, or 80 wt.% and in some embodiments at least 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95 wt.%) or greater of the first part. In this embodiment, the amount of second aliphatic

polyisocyanate is typically at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,

21, 22, 23, 24, 25 wt.% or greater of the first part.

Various other mixtures of aliphatic polyisocyanates based on hexamethylene-1,6- diisocyanate (HDI) can be used. In some embodiments, the mixtures comprise three or four different polyisocyanates.

In some embodiments, the first part is substantially free of other "amine reactive resin(s)"

(i.e. a resin containing functional groups capable of reacting with primary or secondary amines).

For example, the first part is typically free of aromatic amine reactive resins. The first part may also be free of epoxy functional compounds and compounds containing unsaturated carbon-carbon bonds capable of undergoing "Michael Addition" with polyamines (e.g. monomeric or oligomeric polyacrylates). The first part may optionally comprise non-reactive resins or the composition may be free of non-reactive resins.

The second part of the two-part coating comprises one or more polyamines. As used herein, polyamine refers to compounds having at least two amine groups, each containing at least one active hydrogen (N-H group) selected from primary amine or secondary amine. In some embodiments, the second component comprises or consists solely of one or more (e.g. secondary) polyamines. In a preferred coating composition, as described herein the amine component comprises at least one (e.g. aliphatic) aspartic acid ester polyamine (e.g. diamine). Therefore, such polyamine comprises secondary amine substituentsthat includes ester groups and specifically diester moieties

Aspartic acid ester polyamines, are described in US2010/0266762; incorporated herein by reference. Preferred aspartic ester amines have the following formula:

(Formula 3) wherein R12 is a divalent organic group (up to 40 carbon atoms), and each R13 is independently an organic group inert toward isocyanate groups at temperatures of 100°C or less.

In the above formula, preferably, Rms an aliphatic group (preferably, having 1-20 carbon atoms), which can be branched, unbranched, or cyclic. More preferably, R12 is selected from the group of divalent hydrocarbon groups obtained by the removal of the amino groups from 1,4- diaminobutane, 1,6-diaminohexane, 2,2,4- and 2,4,4-trimethyl-l,6-diaminohexane, l-amino-3,3,5- trimethyl-5-aminomethyl-cyclohexane, 4,4'-diamino-dicyclohexyl methane or 3,3-dimethyl-4,4'- diamino-dicyclohexyl methane.

In some embodiments, R12 preferably comprises a dicyclohexyl methane group or a branched C4 to C12 group. R13 is typically independently a lower alkyl group (having 1-4 carbon atoms).

Suitable aspartic acid esters are commercially available from Bayer Corp. under the trade designations "DESMOPHEN H 1420", "DESMOPHEN NH 1520" and "DESMOPHEN H 1220".

DESMOPHEN NH 1220 is substantially composed of the following compound Formula 4;

fciOOC COOEt wherein Et is ethyl. (Formula 4)

The inclusion of aspartic acid esters according to Formula 3, wherein R is a branched or unbranched group lacking cyclic structures and having less than 12, 10, 8, or 6 carbon atoms, such as depicted in Formula 4, is typically preferred for faster film set times of 2 to 5 minutes. The inclusion of an aspartic acid ester according to Formula 3, wherein R¹² comprises unsubstituted cyclic structures can be employed to extend the film set time to 5 to 10 minutes. The inclusion of an aspartic acid ester according to Formula 3, wherein R¹² comprises substituted cyclic structures, (e.g. Formula III of US 2010/0266764, can even further extend the film set time). In some embodiments, such aspartic acid esters are employed at only small concentrations in combination with another aspartic acid ester that provides faster film set times, as just described.

The concentration of aspartic ester polyamine(s) is greater than 40 wt.-% of the second part or greater than 20 or 25 wt.-% of the total polyurea coating composition. The amount of aspartic ester polyamines(amine) may be at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100 wt.-% of the polyamines of the second part or at least 30, 35, 40, 45, or 50 wt.-% of the total polyurea coating composition.

In some embodiments, the second part comprises other optional amine components in an amount less than 40, 35, 30, 25, 20, 15, 10 or 5 wt.-% of the second part or less than 25, 20, 15, 10, or 5 wt.-% of the total polyurea coating composition. When present, the optional other amine components are chosen to dissolve in the liquid aliphatic cyclic secondary diamine (e.g. of Formula 1 and/or 2).

In some embodiments, the second part may optionally further comprise acyclic aliphatic linear or branched polyamines (i.e. that lacks a cyclic group).

One suitable commercially available aliphatic acyclic secondary diamine includes the following:

In some embodiments, the second part comprises one or more aliphatic cyclic secondary diamines that comprise two, optionally substituted, hexyl groups bonded by a bridging group. Each of the hexyl rings comprise a secondary amine substituent. This class of polyamines comprise secondary amine substituents, yet the polyamine lacks ester groups and specifically diester moieties.

The aliphatic cyclic secondary diamine typically has the general structure:

(Formula 1) wherein Ri and R2 are independently linear or branched alkyl groups, having 1 to 10 carbon atoms. Ri and R2 are typically the same alkyl group. Representative alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, and the various isomeric pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. The symbol "S" in the center of the hexyl rings indicates that these cyclic groups are saturated. The preferred Ri and R2 contain at least three carbons, and the butyl group is particularly favored, such as a sec-butyl group.

R3, R4, R5 and R₆ are independently hydrogen or a linear or branched alkyl group containing 1 to 5 carbon atoms. R3, and R₄ are typically the same alkyl group. In some embodiments, R5 and R₆ are hydrogen. Further, in some embodiments, R3, and R₄ are methyl or hydrogen.

The substituents are represented such that the alkylamino group may be placed anywhere on the ring relative to the CR5R6 group. Further, the R3 and R₄ substituents may occupy any position relative to the alkylamino groups. In some embodiments, the alkylamino groups are at the 4,4'- positions relative to the CR5R6 bridge. Further, the R3 and R₄ substituents typically occupy the 3- and 3'-positions.

Commercially available aliphatic cyclic secondary diamines having this structure include:

Stafford, TX)

In another embodiment, the second part optionally comprises one or more aliphatic cyclic secondary diamines that comprise a single hexyl ring. The aliphatic cyclic secondary diamine typically has the general structure:

(Formula 2) wherein R₇ and Rs are independently linear or branched alkyl groups, having 1 to 10 carbon atoms or an alkylene group terminating with a -CN group. R7 and Rs are typically the same group. Representative alkyl groups include the same as those described above for Ri and R2. In one embodiment, R₇ and Rs are alkyl groups having at least three carbons, such as isopropyl. In another embodiment, R₇ and Rs are short chain (e.g. C1-C4) alkylene groups, such as ethylene, terminating with a -CN group.

R9, Rio and R11 are independently hydrogen or a linear or branched alkyl group having 1 to 5 carbon atoms. R9, Rio and R11 are typically the same alkyl group. In some embodiments, R9, Rio and R11 are methyl or hydrogen. In one embodiment R9, Rio and R11 are methyl groups. The substituents are represented such that the alkylamino group may be placed anywhere on the ring relative to the -NR₈ group. In some embodiments, the alkylamino group is 2 or 3 positions away from the - R₈. The preferred alkylamine group is two positions away from the - R₈ group on the cyclohexyl ring.

In some embodiments, the aliphatic cyclic secondary diamine is prepared by the reaction product of (1 equivalent of) isophorone diamine and (2 equivalents of) a Michael acceptor group that reduces the nucleophilicity of the resulting secondary amine groups. Representative Michael acceptors include acrylonitrile and α,β-unsaturated carbonyl compounds, with acrylonitrile typically preferred. In some embodiments, the alkylene group between the terminal -CN group and the amine group has at least two carbon atoms.

Commercially available aliphatic cyclic secondary polyamines (e.g. diamines) having this structure include:

In some embodiments, the isocyanate-reactive component of the second part may include at least one aliphatic cyclic secondary diamine comprising two hexyl rings bonded by a bridging group (e.g. a specie or species according to Formula 1) and at least one aliphatic cyclic secondary diamine comprising a single hexyl ring (e.g. a specie or species according to Formula 2).

The amount of aspartic ester polyamine(s) can range up to 100%. However, in typical embodiments, the second part further comprises filler(s), such as a thixotrope. In some embodiments, the liquid mixture of the first and second part optionally further comprises a polyether component. In some embodiments, the polyether component may be an isocyanate functional polyether, such as DESMODUR XP 2599. The polyether component may also be an isocyanate-functional prepolymer, where an alcohol or amine functional polyether is added to a large molar excess of isocyanate compound. The polyether component may also be an amine-functional prepolymer, where an isocyanate functional polyether is added to a large molar excess of polyamine.

In typical embodiments, the polyether component comprises one or more amine functional polyethers, such as the JEFF AMINE series of polyether amines. Common types of amine functional polyethers include for example amine-terminated polypropylene oxide, amine- terminated polyethylene oxide (PEG), amine-terminated polytetramethylene oxide, etc.

The polyether amines may be either primary or secondary and are available in various molecular weights and functionality. In typical embodiments, the molecular weight is at least 100, 150, or 200 g/mol. In typical embodiments, the molecular weight is no greater than about 10,000; 9,000; 8,000; 7,000; 6,000 or 5,000 g/mol.

Commercially available (e.g. primary and secondary) polyether amines include the following:

(Huntsman, The Woodlands, TX) In some embodiments, the polyether component is amine functional polyether(s) or a combination of at least one isocyanate functional polyether and at least one amine functional polyether.

In some embodiments, the first and/or second part comprises one or more polyether components such that the polyether content of the total composition (i.e. liquid mixture of first and second part) is at least 1, 1.5, 2, or 2.5 wt.%. In some embodiments, the total polyether content is at least 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 8, 9.5 or 10 wt.-%. In other embodiments, the total polyether content is at least 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5 or 15 wt.-%. In some embodiments, the polyether content of the total composition (i.e. liquid mixture of first and second part) is preferably less than 25, 24, 23, 22 or 21 wt.-%.

The inclusion of one or more polyether components can increase the elongation. In typical embodiments, the elongation is no greater than 25% or 20% and in some embodiments, no greater than 19, 18, 17, 16 or 15%.

In some embodiments, the total composition (i.e. first and second part) is substantially free of aromatic components, such that the composition meets the NSF/ANSI Standard. In some embodiments, the total composition typically comprises less than 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 or 0.5 wt.-% of aromatic components.

The average functionality (favg) of the reactive components (e.g. polyisocyanates, polyamines, etc.) of the total composition can be calculated using Equation 1, where Ni is the number of moles of a given reactant, and is the functionality of that reactant. The functionality of the reactant can be obtained by division of the molecular weight of the reactant by the equivalent weight of the reactant. It is appreciated that fillers (inclusive of pigments, thixotropes, and desiccants (i.e. molecular sieves or other solid drying agents described above), and other additives are not reactive components and are excluded for the calculation of favg.

V * f.

^— v a?

Equation 1. Calculation of average functionality It has been found that increasing the average functionality can contribute to increasing the calculated 50 year creep rupture tensile strength. In some embodiments, the average functionality is at least 2.30, 2.31, 2.32, 2.33, 2.34, 2.35, 2.36, 2.37, 2.38, 2.39, or 2.40. In other embodiments, the average functionality is at least 2.41, 2,42, 2.43, 2.44, 2.45, 2.46, 2.47, 2.48, 2.49, or 2.50. In typical, embodiments, the average functionality is less than 2.65, 2.64, 2.63, 2.62, 2.61, or 2.60.

In some embodiments, the above functionality is achieved utilizing one or more

polyisocy antes each having a functionality greater than 2. However, the above functionality can also be achieved by utilizing a polyisocy anate having a functionality of 2 in combination with a second polyisocyante having a functionality greater than 2.

The first and/or second part may comprise a filler. A filler is a solid, insoluble particulate material often employed to add bulk volume or to extend the pigment capabilities without impairing the reactive chemistry of the coating mixture. Many fillers are natural inorganic minerals such as talc, clay (e.g. kaolin), calcium carbonate (e.g. whiting), dolomite (calcium magnesium carbonate), and siliceous fillers including silica (e.g. particle size greater than 1 micron).

Pigments, such as titanium dioxide, can concurrently function as a colorant and filler.

Further, molecular sieves (e.g. aluminosilicate) can concurrently function as a desiccant and a filler. Inorganic thixotropes, such as fumed silica, can concurrently function as a thixotrope and a filler. Other thixotropes comprise an organic material such as polyamides, waxes, castor oil derivatives, and others, as described for example in US 4,923,909 and US 5, 164,433. These may be soluble and/or semisoluble in the resin and are not considered "fillers".

Other fillers include ceramic microspheres, hollow polymeric microspheres such as those available from Akzo Nobel, Duluth, GA, (under the trade designation "EXPANCEL 551 DE"), and hollow glass microspheres (such as those commercially available from 3M Company, St. Paul,

MN, under the trade designation "K37"). Hollow glass microspheres are particularly advantageous because they demonstrate excellent thermal stability and a minimal impact on dispersion viscosity and density. Other fillers can be solid insoluble particulates comprised of insoluble organic matter. Exemplary fillers of this type could include nylon, polyethylene, polypropylene, polyamides, etc.

In some embodiments, the filler may further comprise a surface treatment compound. In some embodiments, the surface treatment compound may be non-reactive with respect to the reactive components (e.g. amine(s) and isocyanate) of the first and second part. For example, polydimethylsiloxane, as can be present as a surface treatment compound on the fumed silica thixotrope, is an example of a non-reactive surface treatment compound.

To avoid applying multiple coating layers, it is advantageous to apply a coating at a thickness or caliper greater than 5 mm. In order to apply a caliper of at least 5 mm in a single pass, the composition typically comprises thixotrope filler, other fillers, or a combination thereof. Thixotropes often can provide a suitable viscosity at lower concentrations than other types of filler and therefore can be advantageous for reducing the filler concentration.

With reference to FIG. 1, pipe 100 illustrates the polyurea coating composition 150, as described herein, having a caliper of at least 5 mm. In contrast, with reference to FIG. 2, pipe 200 illustrates the polyurea coating composition (250 and 260) not having a caliper of at least 5 mm. When the viscosity of the liquid mixture is too low, the coating sags such that portion 250 may have a thickness greater than 5 mm. However, portions 260 have a caliper significantly less than 5 mm.

Filler is preferably employed in the coating composition (i.e. liquid mixture of first and second part) at a concentration no greater than 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or 1% by volume.

In some embodiments, the second part comprises at least 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 wt.-% or greater of thixotrope in order that a coating of sufficient caliper can be applied in a single pass. The concentration of thixotrope in the second part is typically no greater than 30 wt- %. The first part may also comprise thixotrope. The concentration of thixotrope in the first part can be less than the second part depending on the viscosity (e.g. molecular weight) of

polyisocyanate(s). In some embodiments, the amount of thixotrope in the first part is the same range as just described for the second part. In other embodiments, the second part comprises up to 1, 1.5, 2, 2.5, or 3 wt.-% of thixotrope. In some embodiments, the amount of thixotrope employed in the coating composition (i.e. liquid mixture of first and second part) is at least 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 wt.-%. In some embodiments, the concentration of thixotrope employed in the coating composition (i.e. liquid mixture of first and second part) is no greater than 30, 25, 20, 15% or 10 wt.-%.

The first and/or second part may comprise various additives as are known in the art, provided the inclusion of such is permitted with the requirements of the NSF/ANSI Standard. For example, dispersing and grinding aids, defoamers, etc., can be added to improve the

manufacturability, the properties during application, and/or the shelf life. The stoichiometry of the polyurea reaction is based on a ratio of equivalents of isocyanate (e.g. modified isocyanate and excess isocyanate) of the first component to equivalents of amine of the second component. The first and second components are reacted at a stoichiometric ratio of at least about 1 : 1. Preferably, the isocyanate is employed in slight excess, such that the first part is combined with the second part at a ratio of 1.1 to 1.4 equivalents isocyanate to amine. To simplify application in typical embodiments, the first and second part are formulated such that the stoichiometric ratio is obtained at a volume ratio of 1 : 1. However, other volume ratios can be employed, typically ranging from 1 :3 to 3 :2. When the first and second part are combined at a particular volume ratio (e.g. 1 : 1) the weight percent of each of the components in the total coating composition (i.e. liquid mixture of first and second part) can be calculated based of the wt.-% of the part and the density of the component. Typical amounts of each of the components in the total coating composition are set forth in the following table. Other specific amounts can be derived from the wt.-% of the part as previously described and the density of a particular component as described in Table 1 of the examples.

The first and second parts are preferably each liquids at temperatures ranging from 5°C to 25°C, 30°C, 35°C, or 40°C. In view of the confined spaces within the pipeline and the resultant lack of suitable outlet for vapor, both the first part and the second part are substantially free of any volatile solvent. That is to say, solidification of the system applied to the pipeline interior is not necessitated by drying or evaporation of solvent from either part of the system. To further lower the viscosity, one or both parts can be heated. Further, the coating composition has a useful shelf life of at least 6 months, more preferably, at least one year, and most preferably, at least two years.

Although a wide range of formulations are possible, such as exemplified in the forthcoming examples, the coating compositions described herein are particularly suitable for water distribution pipes, typically having a diameter > 3 inches (7.6 cm) up to about 36 inches (91 cm). It is generally desired that the cured coating has sufficient long term strength (i.e. 50 year creep rupture tensile strength) and ductility (i.e. flexibility as characterized by elongation at break) to remain continuous in the event of a subsequent circumferential fracture of a partially deteriorated (e.g. cast iron) pipe, such that the cured coating continues to provide a water impervious barrier between the flowing water and internal surfaces of the pipe. The following table describes typical and preferred properties of cured coating compositions for water distribution pipes as determined by the test methods described US Patent Application No. 62/527508.

Preferred Performance Ranges for Structural Coatings

The coating compositions described herein advantageously provide these desired properties while complying with NSF/ANSI Standard 61-2008, (i.e. the standard for the United States) and are also believed to comply with Regulation 31 of the Water Supply (Water Quality) Regulations (i.e. the standard for the United Kingdom).

The coating composition is typically applied directly to the internal surfaces of a pipe without a primer layer applied to the surface. This can be done using various spray coating techniques. Typically, the amine component and the isocyanate component are applied using a spraying apparatus that allows the components to combine immediately prior to exiting the apparatus. In carrying out the method of the invention, the first and second parts of the system are fed independently, e.g. by flexible hoses, to a spraying apparatus capable of being propelled through an existing pipeline to be renovated. For example, a remote-controlled vehicle, such as described in US 2006/0112996, may enter the pipeline to convey the spraying apparatus through the pipeline. The apparatus preferably heats the two parts of the system prior to application to the pipeline interior and mixes the two parts immediately before applying the mixture to the interior surface of the pipeline. The mixture of the two parts cures on the interior surface of the pipeline to form a (e.g. monolithic) water impervious lining. Such linings may be formed when the pipeline is initially laid, or after a period of use when the pipeline itself begins to deteriorate. Thus, the pipeline is typically buried underground at the time the coating composition is applied. The liquid mixture can be applied at various thickness. In some embodiments, the coating is present at a caliper ranging from about 1 to 15 mm. Multiple coating layers can be applied to obtain the desired caliper. Notably, the composition described herein can be applied at a caliper of at least 5 mm in a single pass forming a cured continuous lining.

A variety of spray systems may be employed as described in the art. In some embodiments, a heated airless spray apparatus, such as a centrifugal spinning head is employed. In another embodiment, an airless, impingement mixing spray system is employed and generally includes the following components: a proportioning section which meters the two components and increases the pressure to above about 1500 psi (10.34 MPa); a heating section to raise the temperatures of the two components (preferably, independently) to control viscosity; and an impingement spray gun which combines the two components and allows mixing just prior to atomization. In other embodiments, the liquid mixture (e.g. coating composition) is heated and applied with an (e.g. air vortex) spray apparatus.

In some embodiments and in particular when the liquid mixture is applied by spraying, the first and second part typically each have a (Brookfield) viscosity ranging from about 5,000 centipoise (cps) to about 60,000 cps (using spindle 6 with a spindle speed of 20 revolutions per minute (RPM)) at the temperature at which the liquid mixture is applied. The temperature at which the liquid mixture is applied typically ranges from about 15°C to 50°C.

Viscosity behavior of each of the two components is important for two-part spray-coating processes. With impingement mixing, the two parts should be as close as possible in viscosity at high shear rates to allow adequate mixing and even cure. The plural component static mix/spray system appears to be more forgiving of viscosity differences between the two components.

Characterization of viscosities as functions of shear rate and temperature can help with decisions as to starting points for temperatures and pressures of the coatings in the two part spray equipment lines.

Advantages and embodiments of this disclosure are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. In these examples, all percentages, proportions and ratios are by weight unless otherwise indicated.

These abbreviations are used in the following examples: s = seconds, min = minute, ppb = part per billion, hr = hour, L = liter, mL = milliliter; wt = weight, gpm = gallons per minute, V = volts, cP = centipoise, MPa = megapascals, RPM = revolutions per minute, HP = horsepower, and Mw = molecular weight.

Materials and Methods

The chemicals used with their sources are shown in Table 1. All materials were obtained from commercial sources and used as received. Tab

methylphenol 99%, often alternatively called Tewksbury, (BHT) butylated hydroxytoluene (BHT), MA

Mw 220.35 g/mol, 220.35 g/OH

equivalent

4-sec-Butylphenol 4-sec-Butylphenol (SBP), 96%, 0.98 Sigma-Aldrich (SBP) Mw = 150.22 g/mol, 150.22 g/OH Co., St. Louis, equivalent MO

General method for preparation of resin mixtures

Two part cartridges were acquired: Sulzer Mixpac 1 : 1 cartridges (Sulzer Mixpac

EAAC400-01-10-01, 400 milliliter (mL) 1 to 1 Cartridge Assembly Kit available from Ellsworth Adhesives, Germantown, WI).

Resin formulations of the first and second part were separately blended using a 3 horse power (HP), high dispersion Ross Mixer (Charles Ross and Son Company, St. Charles, IL) equipped with a vacuum attachment. Liquid formulation components were charged into a mixing vessel equipped with a Cowles mixing blade and vacuum was applied to the mixing vessel. The components mixed for 15 minutes at 1200 (RPM). The first and second part compositions were then loaded into opposite sides of the two-part cartridges.

General method for preparation of molded samples

The cartridges were dispensed at room temperature. Each sample was dispensed using a pneumatic cartridge dispenser through a 32 element static mixer (Sulzer Mixpac Static Mixer MCQ 08-32T, BrandyWine Materials, LLC, Burlington, MA). The materials were injected into a closed polytetrafluoroethylene (PTFE) mold (ASTM D638-08 Type IV dogbone, ~ 2 mm thickness). The parts were then demolded and stored in a desiccator for greater than 7 days prior to testing.

Tags/molding excess on the samples were sanded smooth using 400 grit sandpaper.

Gel time measurement test method

Approximately 20 mL of the cartridge contents were dispensed at room temperature using a pneumatic cartridge dispenser through a 32 element static mixer (Sulzer Mixpac Static Mixer MCQ 08-32T, BrandyWine Materials, LLC, Burlington, MA) into a 50 mL polyethylene beaker, and the contents was stirred by hand using a wooden tongue depressor. The time between initial dispensing of the material and when the material could no longer be stirred by hand was recorded. Maximum exotherm temperature measurement test method

A 4 inch x 4 inch x 2 millimeter (mm) (lO cm x 10 cm x 2 mm) deep coating was made using a mold with a stainless steel spatula as a drawdown bar. The temperature of the coating was measured using a V&A VA6530 infrared thermometer. The maximum temperature observed was recorded.

Tensile strength and elongation measurements

Samples were stored for at least thirty days in a desiccator prior to measurements. Tensile strength and elongation were measured from the molded samples according to ASTM D-638-14 using either a MTS 880 servohydraulic load frame or a Sintech 10/D electromechanical load frame. Strain was measured by means of an extensometer with 25.4 mm gage length for both load frames. Test control and data acquisition was performed using TestWorks 4.0 software (MTS Corp., Eden Prairie, MN).

General method for spraying formulations on PVC pipes

Cartridges (Sulzer Mixpac EAAC400-01-10-01) filled with the first part and the second part of resin formulations were heated to 40°C and dispensed using a variable speed screw driven plunger apparatus. Plunger speeds were set to 18 inches/min (46 cm/min). When spraying formulations on PVC pipes, the blended resin is dispensed through a static mixer (Sulzer statomix MC-18) into a centrifugal spinning cone head, the spinning cone is placed onto a translational stage that moves within the pipe interior at a fixed speed. The volumetric rate of the resin in the spinning cone is determined to coincide with the translational speed of the spinning cone relative to the interior of the pipe, thus it is possible to achieve a determined coating thickness. In this case the translational speed was set to approximately 12 inches/min (30.5 cm/min), thus targeting a thickness of 8.3 mm. After the spraying, the coated pipe was left to stand over night at room temperature. Post-lining coating measurements were taken by cutting cross-sections of the coated pipes using a band saw and measuring with a ruler.

Example preparation

All inventive, control, and comparative examples were generated using the general procedure described above. The values described are weight percent for each side of the two-part formulations. All formulations were dispensed using 1 : 1 volume ratio. Formulations for Controls 1 and 2 (CT-1 and CT-2) and Examples 3 to (EX-3 to EX-6)

First Part

Second Part

Formulations for Comparative Examples 9 to 12 (CE-9 to CE-12) and Examples 7, 8 and 13 (EX-7, EX-8, EX-13)

First Part

Second Part

Weight percents in the tables below are of the total composition (liquid mixture of first and second part)

Formulations CT-1 to CT-2 and EX-3 to EX-6

PURMOL 3 ST 1.99 1.99 1.99 1.98 1.97

DESMOPHEN H 48.80 47.83 47.76 47.35 46.94 45.59

1220

Glycerol 0.08 0.52 0.98 2.45

Formulations CE-9 to CE-11 and EX-7, EX-8, and EX-13

Table 2. Results from the addition of various levels of glycerol to solutions of DESMOPHEN NH-1220.

BHT = Butylated hydroxytoluene (2,6-di(tert-butyl)-4-methylphenol), SBP = 4-sec-Butylphenol. Insol. = BHT was insoluble in the resin at that concentration.

As can be seen from Table 2, when molecular sieves are added, the gel time is increased from 240 to 560 seconds, indicating traces of water present in the sample were removed by the sieves. Glycerol was then added at various levels, and it was shown that the gel time decreases from 560 seconds to 50 seconds. If it is desired to speed up the reaction as fast as possible, molecular sieves are not necessary as shown by EX-7, EX-8, and EX-13. Here, gel times decreased from 240 to 56 seconds depending on concentration of functional group and which alcohol used. Unhindered phenols such as sec-butyl phenol were especially efficient catalysts when compared to others on a per hydroxyl group concentration basis, while glycerol is extremely efficient in terms of a per wt. % basis.

Claims

What is claimed is:

1. A method of forming a coating on a surface of a pipeline, the method comprising the steps of:

a) providing a polyurea coating composition comprising

a first part comprising at least one polyisocyanate; and

a second part comprising greater than 40 wt.-% of aspartic acid ester polyamine; and

b) combining the first part and the second part to form a liquid mixture;

wherein the first part, second part, or liquid mixture further comprises a hydroxyl component having sufficiently reactivity such that when the hydroxyl component is present at a concentration no greater than 5 wt.-%, the gel time is reduced by at least 50% relative to the same composition without the hydroxyl component; c) applying the liquid mixture to internal surfaces of the pipeline; and d) allowing the mixture to set forming a cured coating.

2. The method of claim 1 wherein the polyurea coating composition is provided with the hydroxyl component(s) contained within the first and/or second part.

3. The method of claim 1 wherein the polyurea coating composition is provided without hydroxyl component(s) and hydroxyl component(s) are added to the second part prior to combining the first and second part or during combining the first part and the second part.

4. The method of claims 1-3 further comprising a water scavenger that is non-reactive with water and non-reactive with the first and second part.

5. The method of claims 1-4 wherein the hydroxyl component is a liquid at 25°C or a solid that is soluble with the second part.

6. The method of claims 1-5 wherein the hydroxyl component is aliphatic.

7. The method of claims 1-6 wherein the hydroxyl component is selected from the group consisting of alcohols and polyols having a molecular weight per hydroxyl group ranging from 30 to 1000 g/hydroxyl group.

8. The method of claims 1-7 wherein the hydroxyl component is present in an amount ranging from 0.05 to 10 wt-%.

9. The method of claims 1-8 wherein the tensile strength is at least 90-100% of the same composition without the hydroxyl component.

10. The method of claims 1-9 wherein the polyisocyanate is aliphatic.

11. The method of claim 10 wherein the polyisocyanate is a derivative of

hexamethylene diisocyanate, a derivative of isophorone diisocyanate, a derivative of hexamethylene diisocyanate and isophorone diisocyanate, or a mixture thereof.

12. The method of claims 1-11 wherein the liquid mixture further comprises filler.

13. The method of claims 1-12 wherein the liquid mixture has a poly ether content of at least 2.5 wt.-%.

14. The method of claim 13 wherein the polyether content is derived at least in part from a polyether poly amine, a polyisocyanate, the hydroxyl component, or a combination thereof.

15. The method of claims 1-14 wherein the pipeline is a drinking water pipeline and the cured coating contacts drinking water.

16. A method of accelerating the reaction rate of a polyurea coating composition comprising

a) providing a polyurea coating composition comprising

a first part comprising at least one polyisocyanate, and

a second part comprising greater than 40 wt.-% of aspartic acid ester polyamine; and b) combining the first part and the second part to form a liquid mixture;

wherein the first part, second part, or liquid mixture further a hydroxyl component having sufficiently reactivity such that when the hydroxyl component is present at a concentration no greater than 5 wt.-%, the gel time is reduced by at least 50% relative to the same composition without the hydroxyl component.

17. The method of claim 16 wherein the coating composition is further characterized by any one or combination of claims 2-14.

18. A polyurea coating composition, comprising:

a) a first part comprising at least one polyisocyanate, and

b) a second part comprising greater than 40 wt.-% of aspartic acid ester polyamine and a hydroxyl component having sufficiently reactivity such that when the hydroxyl component is present at a concentration no greater than 5 wt.-%, the gel time is reduced by at least 50% relative to the same composition without the hydroxyl component.

19. A polyurea coating composition, comprising:

a) a first part comprising at least one polyisocyanate, and

b) a second part comprising greater than 40 wt.-% of aspartic acid ester polyamine,

c) a third part comprising a hydroxyl component having sufficiently reactivity such that when the hydroxyl component is present at a concentration no greater than 5 wt.-%, the gel time is reduced by at least 50% relative to the same composition without the hydroxyl component.

20. The polyurea coating composition of claims 18-19 wherein the coating

composition is further characterized by any one or combination of claims 2-14.

21. An article comprising the polyurea coating composition of claims 28-30 wherein the coating composition is cured.