阅读说明：本技术 一种用于耐候面漆的水性环氧树脂的分散体和包含其的涂料组合物 (Aqueous epoxy resin dispersion for weather-resistant finish paint and coating composition containing same ) 是由 沈岳 吕宏飞 沈君岱 伍宽平 于 2020-12-18 设计创作，主要内容包括：本发明提供了一种用于耐候面漆的水性环氧树脂,其结构式如式I所示。本发明还提供了包括上述用于耐候面漆的水性环氧树脂的分散体。本发明还提供了一种包含水性环氧树脂的分散体的涂料组合物。本发明提供的水性环氧树脂具有良好的耐候性,可以厚涂而不产生气泡,与现有的PU面漆相比具有类似的抗紫外线性能,可以使用湿碰湿工艺来减少等待时间和提高效率；利用该水性环氧树脂制得的可固化涂料组合物在环境温度下具有1小时或更少的表干时间和12小时或更少的干硬时间。(The invention provides a water-based epoxy resin for a weather-resistant finish paint, which has a structural formula shown as a formula I. The invention also provides a dispersion containing the waterborne epoxy resin for the weather-resistant finishing paint. The invention also provides a coating composition comprising a dispersion of an aqueous epoxy resin. The waterborne epoxy resin provided by the invention has good weather resistance, can be thickly coated without generating bubbles, has similar ultraviolet resistance compared with the existing PU finishing paint, and can reduce waiting time and improve efficiency by using a wet-on-wet process; a curable coating composition prepared using the waterborne epoxy resin has a tack-free time of 1 hour or less and a dry-hard time of 12 hours or less at ambient temperature.)

1. A water-based epoxy resin for a weather-resistant finish paint has a structural formula shown as a formula I:

2. the preparation method of the water-based epoxy resin for the weather-resistant finish paint, which is disclosed by claim 1, is characterized in that: in the presence of benzoyl peroxide, epoxy resin, methyl methacrylate and vinyl triethoxysilane react at 80-120 ℃ to obtain the epoxy resin-modified methyl methacrylate copolymer; the molar ratio of the epoxy resin, the methyl methacrylate and the vinyl triethoxysilane is 1: (2-6): (1-2); the reaction formula is as follows:

3. a dispersion comprising the aqueous epoxy resin for weatherable topcoats of claim 1.

4. The method of preparing the dispersion of waterborne epoxy resin for weatherable topcoats of claim 3, wherein: and (3) adding the waterborne epoxy resin for the weather-resistant finish paint into water with the temperature of 60-80 ℃, and stirring and dispersing to obtain the weather-resistant finish paint.

5. A coating composition comprising a dispersion of an aqueous epoxy resin, characterized in that: comprising the dispersion of claim 3, further comprising an aqueous amine curing agent; the molar ratio of the dispersion to the aqueous amine curing agent is 1 (0.9-2).

6. The coating composition of claim 5, wherein: the waterborne amine curing agent is one or a combination of more of aliphatic amine, cycloaliphatic amine, heterocyclic amine, polyether amine and addition products thereof; the aqueous amine curing agent is diamine or polyamine.

7. The coating composition of claim 6, wherein: the aliphatic amine comprises Ethylenediamine (EDA), Diethylenetriamine (DETA), triethylene tetramine (TETA), Trimethylhexamethylenediamine (TMDA), tetraethylethylenediamine, Hexamethylenediamine (HMDA), 1, 6-hexamethylenediamine, N- (2-aminoethyl) -1, 3-propanediamine, N' -1, 2-ethanediylbis-1, 3-propanediamine and dipropylenetriamine; the cycloaliphatic amines include, for example, Isophoronediamine (IPDA), 4' -diaminodicyclohexylmethane (PACM), 1, 2-Diaminocyclohexane (DACH), 1, 4-cyclohexanediamine, bis (aminomethyl) norbornane; the heterocyclic amines include piperazine, Aminoethylpiperazine (AEP); the polyether amine comprises bis (aminopropyl) ether and polyamide.

8. The coating composition of claim 6, wherein: the composite material also comprises an accelerant, wherein the accelerant comprises one or a combination of more of benzyl alcohol, 2, 4, 6-tri- (N, N-dimethylaminomethyl) -phenol and salicylic acid.

9. The coating composition of claim 6, wherein: the paint also comprises inorganic additives and/or pigments, wherein the inorganic additives are ceramic materials, and the ceramic materials comprise zinc oxide, titanium dioxide, metal nitride (boron nitride), metal carbide, metal sulfide (molybdenum disulfide, tantalum disulfide, tungsten disulfide and zinc sulfide), metal silicate (aluminum silicate and magnesium silicate, vermiculite, metal boride and metal carbonate); the mass of the inorganic additive and/or pigment is 5-60%, preferably 10-40% of the total mass of the coating composition.

10. The coating composition of claim 6, wherein: further comprising other additives including defoamers, plasticizers, antioxidants, light stabilizers, uv absorbers, uv blockers OMPUNT, flow control agents, catalysts and accelerators; the mass of the other additives accounts for 0.001-10%, preferably 0.01-2% of the total mass of the coating composition; the film-forming agent also comprises a cosolvent and/or a film-forming auxiliary agent, wherein the cosolvent comprises alcohol organic solvents (n-butyl alcohol, ethylene glycol and propylene glycol) and ether organic solvents (propylene glycol butyl ether, glycol ether, propylene glycol monomethyl ether and ethylene glycol dimethyl ether); the mass of the organic solvent accounts for 0.5-10%, preferably 0.5-5% of the total mass of the coating composition.

Technical Field

The invention relates to a waterborne epoxy resin for a weather-resistant finish paint and a dispersion thereof, and also relates to an application of the waterborne epoxy resin dispersion in outdoor weather-resistant paint, belonging to the field of paint.

Background

The present invention relates to weatherable 2K waterborne epoxy compositions for maintenance and protective coating (M & PC) applications. 2K epoxy is the most important class of thermosetting polymers and has wide application in protective coatings. However, 2K epoxies are the most commonly used primers, not topcoats, because their outdoor weathering performance is not satisfactory. In the protection process, the epoxy is easy to have yellowing and chalking and light loss. Thus, cost-effective corrosion-resistant bisphenol a type epoxy resins have been widely used as corrosion-resistant primers for M & PC applications, while 2K Polyurethane (PU) compositions with weathering properties have been widely used as protective top coats for M & PC applications. Although there has been a study of weather resistant epoxy in the direction of oil based coatings, waterborne epoxy is naturally used as an anticorrosion primer for M & PC applications during the conversion of oil based industrial coatings to waterborne, and correspondingly, waterborne 2K Polyurethane (PU) compositions with weather resistant properties have been widely used as protective top coats for M & PC applications.

Waterborne polyurethanes find several disadvantages in applications: 1. the paint film can not be thickly coated and has the maximum thickness of the explosion bubble. The water content in the construction of the water-based polyurethane coating is firstly reacted with the curing agent isocyanate to generate a large amount of gas, so that a paint film is easy to foam. 2. The "wet-on-wet" process cannot be used to reduce latency and improve efficiency.

Disclosure of Invention

The technical problem is as follows: in order to solve the defects of the prior art, the invention aims to provide a water-based epoxy resin for a weather-resistant finishing paint and a dispersion thereof.

The technical scheme is as follows: the invention provides a water-based epoxy resin for a weather-resistant finish paint, which has a structural formula shown as a formula I:

the invention also provides a preparation method of the waterborne epoxy resin, which comprises the steps of reacting the epoxy resin, methyl methacrylate and vinyl triethoxysilane at 80-120 ℃ in the presence of benzoyl peroxide to obtain the waterborne epoxy resin; the molar ratio of the epoxy resin, the methyl methacrylate and the vinyl triethoxysilane is 1: (2-6): (1-2); the dosage of the benzoyl peroxide is a catalytic amount; the reaction formula is as follows:

the invention also provides a dispersion containing the waterborne epoxy resin for the weather-resistant finishing paint.

The invention also provides a preparation method of the aqueous epoxy resin dispersoid for the weather-resistant finish paint, which is prepared by adding the aqueous epoxy resin for the weather-resistant finish paint into water with the temperature of 60-80 ℃ and stirring for dispersion.

The invention also provides a coating composition comprising a dispersion of an aqueous epoxy resin, comprising the dispersion of claim 3, further comprising an aqueous amine curing agent; the molar ratio of the dispersion to the aqueous amine curing agent is 1 (0.9-2).

Preferably, the aqueous amine curing agent is one or a combination of several of aliphatic amine, cycloaliphatic amine, heterocyclic amine, polyether amine and addition products thereof; the aqueous amine curing agent is diamine or polyamine.

Preferably, the fatty amines include Ethylenediamine (EDA), Diethylenetriamine (DETA), triethylenetetramine (TETA), Trimethylhexamethylenediamine (TMDA), tetraethylethylenediamine, Hexamethylenediamine (HMDA), 1, 6-hexamethylenediamine, N- (2-aminoethyl) -1, 3-propanediamine, N' -1, 2-ethanediylbis-1, 3-propanediamine, dipropylenetriamine; the cycloaliphatic amines include, for example, Isophoronediamine (IPDA), 4' -diaminodicyclohexylmethane (PACM), 1, 2-Diaminocyclohexane (DACH), 1, 4-cyclohexanediamine, bis (aminomethyl) norbornane; the heterocyclic amines include piperazine, Aminoethylpiperazine (AEP); the polyether amine comprises bis (aminopropyl) ether and polyamide.

Preferably, the pesticide also comprises an accelerator, wherein the accelerator comprises one or more of benzyl alcohol, 2, 4, 6-tri- (N, N-dimethylaminomethyl) -phenol and salicylic acid.

Preferably, the paint also comprises inorganic additives and/or pigments, wherein the inorganic additives are ceramic materials, and the ceramic materials comprise zinc oxide, titanium dioxide, metal nitrides (boron nitride), metal carbides, metal sulfides (molybdenum disulfide, tantalum disulfide, tungsten disulfide and zinc sulfide), metal silicates (aluminum silicate and magnesium silicate, vermiculite, metal borides, metal carbonates); the mass of the inorganic additive and/or pigment is 5-60%, preferably 10-40% of the total mass of the coating composition.

Preferably, further additives are included, including defoamers, plasticizers, antioxidants, light stabilizers, uv absorbers, uv blockers OMPUNT, flow control agents, catalysts and accelerators; the mass of the other additives accounts for 0.001-10%, preferably 0.01-2% of the total mass of the coating composition; the film-forming agent also comprises a cosolvent and/or a film-forming auxiliary agent, wherein the cosolvent comprises alcohol organic solvents (n-butyl alcohol, ethylene glycol and propylene glycol) and ether organic solvents (propylene glycol butyl ether, glycol ether, propylene glycol monomethyl ether and ethylene glycol dimethyl ether); the mass of the organic solvent accounts for 0.5-10%, preferably 0.5-5% of the total mass of the coating composition.

Has the advantages that: the waterborne epoxy resin provided by the invention has good weather resistance, can be thickly coated without generating bubbles, has similar ultraviolet resistance compared with the existing PU finishing paint, and can reduce waiting time and improve efficiency by using a wet-on-wet process; a curable coating composition prepared using the waterborne epoxy resin has a tack-free time of 1 hour or less and a dry-hard time of 12 hours or less at ambient temperature.

The waterborne epoxy resin achieves satisfactory weatherability to less than 30% loss of gloss as measured by ASTM G154-6 for at least 400 hours. Preferably, the coating film has a gloss loss of less than 30% after more than 500 hours, more than 600 hours, more than 700 hours, even more than 900 hours of testing.

The epoxy resin composition of the present invention is prepared by a high speed dispersion process of a surfactant (a nonionic surfactant of the Dailaizi chemical, HD890E, on the Shanghai) to form a high solids dispersion with a solids content of more than 50%, preferably more than 60%. The particle size distribution of the dispersion obtained by light scattering measurement has a volume mean diameter < 0.5 micrometer, preferably < 0.3 micrometer, more preferably < 0.1 micrometer. The resulting dispersion was shelf and hot box stable, i.e., it did not exhibit a significant change in viscosity or phase separation upon exposure to a 50 ℃ environment for 30 days.

The curable coating compositions prepared using the waterborne epoxy resins are suitable for use in a variety of coating applications, such as marine coatings, protective coatings, automotive coatings, wood coatings, coil coatings, and plastic coatings, and are particularly suitable for topcoat applications. It can be applied to and adhered to a variety of substrates, including wood, metal, plastic, foam, including flexible substrates, or substrates found on automobiles, the substrates typically comprising a primer coating, examples of which include epoxy primers and PU primers.

The curable coating compositions prepared using the waterborne epoxy resins can be applied by conventional methods including brushing, dipping, rolling and spraying, using standard spraying techniques and equipment such as air spraying and electrostatic spraying, electrostatic bell application, or manual or automated methods.

Detailed Description

The following examples are given to further describe the present invention in detail with reference to specific embodiments. The following examples are intended to illustrate the invention, but not to limit the scope of the invention.

The experimental procedures in the following examples are conventional, except for the specific illustrations. The raw materials and test reagents used in the examples were commercially available products except for those specifically mentioned.

Example 1

Adding 1mol of epoxy resin E-44 into a 2L round-bottom flask provided with a reflux condensation, stirring and constant temperature device, and heating to 80 ℃; the mixed monomers (2mol of methyl methacrylate, 1mol of vinyltriethoxysilane and 7 g of benzoyl peroxide) were mixed well beforehand, 1/3 of the mixed monomers were added at 80 ℃ taking care of the exotherm; gradually heating to about 110 ℃ and maintaining for 30 minutes, dropwise adding the remaining 2/3 mixed monomer at about 110 ℃ for about 2.5 hours, and introducing a small amount of nitrogen for protection in the whole process; and preserving the temperature for reaction for 2.5h to obtain the waterborne epoxy resin with the EEW of about 700.

500 g of the above-mentioned aqueous epoxy resin and 50 g of emulsifier HD890E were introduced into a 1 l stainless steel tank with a high-speed dispersing device, stirring was started and distilled water was added while heating to 60 ℃ and 80 ℃, and a dispersing disk on a stirring arm was rotated clockwise at a speed of 6000 rpm. The water addition amount is 450 g, and the dispersion time is 5-10h, so as to obtain the aqueous epoxy resin dispersion with the solid content of 55%.

Example 2

Adding 1mol of epoxy resin E-44 into a 2L round-bottom flask provided with a reflux condensation, stirring and constant temperature device, and heating to 80 ℃; mixing mixed monomers (4mol of methyl methacrylate, 1mol of vinyl triethoxysilane and 7 g of benzoyl peroxide) in advance, adding 1/3 mixed monomers at 100 ℃, paying attention to heat release, gradually heating to about 120 ℃ and maintaining for 30 minutes, dropwise adding the rest 2/3 mixed monomers at about 120 ℃ until the addition is finished for about 2.5 hours, and introducing a small amount of nitrogen for protection in the whole process; and preserving the temperature for reaction for 2.5h to obtain the waterborne epoxy resin with the EEW of about 800.

500 g of the above-mentioned aqueous epoxy resin and 50 g of emulsifier HD890E were introduced into a 1 l stainless steel tank with a high-speed dispersing device, stirring was started and distilled water was added while heating to 60 ℃ and 80 ℃, and a dispersing disk on a stirring arm was rotated clockwise at a speed of 6000 rpm. The water addition amount is 450 g, and the dispersion time is 5-10h, so as to obtain the aqueous epoxy resin dispersion with the solid content of 55%.

Example 3

Adding 1mol of epoxy resin E-44 into a 2L round-bottom flask provided with a reflux condensation, stirring and constant temperature device, and heating to 80 ℃; mixing mixed monomers (6mol of methyl methacrylate, 2mol of vinyl triethoxysilane and 10 g of benzoyl peroxide) in advance, adding 1/3 mixed monomers at 120 ℃, paying attention to heat release, gradually heating to about 120 ℃ and maintaining for 30 minutes, dropwise adding the rest 2/3 mixed monomers at about 120 ℃ until the addition is finished for about 2.5 hours, and introducing a small amount of nitrogen for protection in the whole process; and preserving the temperature for reaction for 2.5h to obtain the waterborne epoxy resin with the EEW of about 800.

500 g of the above-mentioned aqueous epoxy resin and 50 g of emulsifier HD890E were introduced into a 1 l stainless steel tank with a high-speed dispersing device, stirring was started and distilled water was added while heating to 60 ℃ and 80 ℃, and a dispersing disk on a stirring arm was rotated clockwise at a speed of 6000 rpm. The water addition amount is 450 g, and the dispersion time is 5-10h, so as to obtain the aqueous epoxy resin dispersion with the solid content of 55%.

Example 4

A batch of aqueous coating compositions was prepared according to the formulations described in table 1.

Mixing and dispersing the component A and a high-speed dispersant to prepare a component A; then mixing component a with component B and stirring for about 30 minutes to form a topcoat composition; and then spraying the finish paint composition onto the sand blasting cleaning plate coated with the primer by using an air spraying method to obtain the epoxy finish paint sample plate.

TABLE 1

Comparative example 1

The two-component waterborne epoxy coating compositions shown in Table 2 are widely used in the industrial coatings market for producing primers. Part A and part B were mixed and stirred for about 30 minutes to form a topcoat coating composition of comparative example B

TABLE 2

The drying properties of the above-mentioned coating composition and the properties of a coating film formed from the coating composition were evaluated.

Table 3 shows the drying characteristics of the coating compositions of samples 1 to 3 and the coating composition of comparative example 1. They all meet the requirements of industrial coatings.

The coating compositions of samples 1 to 3 had a dry time of less than 2 hours and a hard dry time of within 15 hours at ambient temperature.

The coating composition of comparative example 1 had a tack-free time of 2.5h and a hard-dry time of 17h at ambient temperature.

TABLE 3

Coating formulation	Tack-free time h	Hard dry time h
			Sample 1	2.0	15
Sample 2	1.7	13
			Sample 3	1.8	14
Comparative example 1	2.5	17

Table 4 shows the gloss and the loss of gloss after QUV testing of the cured coatings. The coating industry standards set forth in table 5, samples 1 through 3, meet the standards for some industry finishes, and have weathering performance that meets some industry requirements.

The gloss retention of the epoxy finish prepared in comparative example 1 was very poor and could not meet the requirements of any industry standard.

TABLE 4

TABLE 5

The wet-on-wet test between the epoxy primer and the topcoat was evaluated according to the test method for adhesion. After 20 minutes from the completion of the epoxy primer spraying, topcoat samples 1 to 3 and comparative example 1) were directly sprayed. The panels were then cured at ambient temperature for 7 days.

The test result shows that: the wet-on-wet interlayer adhesion on the epoxy primers of samples 1 to 3 exhibited a 0B rating, while the wet-on-wet interlayer adhesion on the epoxy primer of comparative example 1 exhibited a 5B rating.

In the coating composition of the present invention, the following components are used as components, and the object of the present invention can be achieved:

the waterborne amine curing agent is one or a combination of more of aliphatic amine, cycloaliphatic amine, heterocyclic amine, polyether amine and addition products thereof; the aqueous amine curing agent is diamine or polyamine.

The aliphatic amine comprises Ethylenediamine (EDA), Diethylenetriamine (DETA), triethylene tetramine (TETA), Trimethylhexamethylenediamine (TMDA), tetraethylethylenediamine, Hexamethylenediamine (HMDA), 1, 6-hexamethylenediamine, N- (2-aminoethyl) -1, 3-propanediamine, N' -1, 2-ethanediylbis-1, 3-propanediamine and dipropylenetriamine; the cycloaliphatic amines include, for example, Isophoronediamine (IPDA), 4' -diaminodicyclohexylmethane (PACM), 1, 2-Diaminocyclohexane (DACH), 1, 4-cyclohexanediamine, bis (aminomethyl) norbornane; the heterocyclic amines include piperazine, Aminoethylpiperazine (AEP); the polyether amine comprises bis (aminopropyl) ether and polyamide.

The composite material also comprises an accelerant, wherein the accelerant comprises one or a combination of more of benzyl alcohol, 2, 4, 6-tri- (N, N-dimethylaminomethyl) -phenol and salicylic acid.

The inorganic additive is a ceramic material comprising zinc oxide, titanium dioxide, metal nitrides (boron nitride), metal carbides, metal sulfides (molybdenum disulfide, tantalum disulfide, tungsten disulfide, and zinc sulfide), metal silicates (aluminum and magnesium silicates, vermiculite, metal borides, metal carbonates); the mass of the inorganic additive and/or pigment is 5-60%, preferably 10-40% of the total mass of the coating composition.

The other additives include defoaming agents, plasticizers, antioxidants, light stabilizers, ultraviolet absorbers, ultraviolet blockers OMPUNT, flow control agents, catalysts and accelerators; the mass of the other additives accounts for 0.001-10%, preferably 0.01-2% of the total mass of the coating composition; the film-forming agent also comprises a cosolvent and/or a film-forming auxiliary agent, wherein the cosolvent comprises alcohol organic solvents (n-butyl alcohol, ethylene glycol and propylene glycol) and ether organic solvents (propylene glycol butyl ether, glycol ether, propylene glycol monomethyl ether and ethylene glycol dimethyl ether); the mass of the organic solvent accounts for 0.5-10%, preferably 0.5-5% of the total mass of the coating composition.

The following standard analytical equipment and methods were used in the tests of the present invention.

Acid value measurement

The acid number is measured according to GB/T8995-. The acid number of the resin is defined as the mg KOH per gram of resin necessary to neutralize the resin in a simple titration method with thymol blue as the color indicator. In ethanol solution, KOH is conveniently 0.1N (moles/liter). The resin was dissolved in a mixed solvent of toluene and ethanol (volume ratio 2: 1).

Drying Property

A BYK dry timer was used to record the tack free time of the coating composition according to ASTM D5895. The coating composition to be evaluated was coated on a glass plate having a wet film thickness of 150. mu.m, and then the coated glass plate was placed on a BYK drying timer to be dried at ambient temperature.

Adhesion test

Adhesion between the primer and the topcoat was evaluated by the primer according to ASTM D3359 method. Part B and part A of a primer IGGARD 787 epoxy primer commonly used in the Mg/PC industry was mixed in a 3:1 volume ratio and sprayed onto a blast cleaned panel using an air spray process to form an epoxy primer on the panel. After one hour, the epoxy or polyurethane topcoat composition is sprayed onto the epoxy primer coat. Adhesion between the epoxy primer and the epoxy or PU topcoat was tested after 7 days of curing at 0 ℃ or 7 days at room temperature, respectively. The resulting topcoat had an average thickness of 60 m and the results were 0B, 1B, 2B, 3B, 4B and 5B, respectively, where 5B represents the best adhesion and 0B the worst adhesion between the primer and topcoat.

Artificial weathering test

The artificial weathering test was carried out according to the method ASTM G154-06. The test included the following repeated cycles: UV irradiation at 60 + -3 deg.C for 4 hr, and condensation at 50 + -3 deg.C for 4 hr.

An INTERGARD 787 epoxy primer was spray applied to the grit blasted clean panel and cured at ambient temperature for one day to form a dry film having a thickness of 60-80 m, and then the topcoat composition to be evaluated was spray applied over the resulting primer and cured at ambient temperature for 7 days to form dry f. A film having a thickness of 50 to 60_ m. The 60 ° (°) gloss value and the b value of the coated sheet obtained before and after the artificial climate test for a certain time were evaluated by a BYK micro three-gloss meter according to the ASTM D523 method.

Flexibility

The coating composition to be evaluated was sprayed directly onto tinplate and cured at ambient temperature for 7 days to form a coating film having an average thickness of 30 microns. The coating was tested for crack resistance according to ASTM D522 for cone compliance. If the film does not crack at radium 3.3mm after the test, it is visible to the naked eye, indicating that the coating has good flexibility.

Impact resistance

The coating composition to be evaluated was sprayed directly onto tinplate and cured at ambient temperature for 7 days to form a coating film having an average thickness of 30 microns. The impact resistance of the coating film was evaluated according to the method of ASTM 2794.

Epoxy Equivalent Weight (EEW) analysis

The percentage of epoxy resin in the epoxy resin was determined by standard titration. The titration method used was similar to that described in Jay, r.r., "direct titration of epoxy and azide", analytical chemistry, 36, 3, 667-one 668 (3 months 1964). In a modification of the method, a carefully weighed sample (sample weight range 0.17-0.25 g) was dissolved in dichloromethane (15ml) and then tetraethylammonium bromide solution was added to acetic acid (15 ml). The resulting solution treated with 3 drops of crystal violet indicator (0.1% w/v) was titrated with 0.1N perchloric acid in acetic acid on a Metrohm 665 dose titrator (Brinkmann). Titration of a blank consisting of dichloromethane (15mL) and tetraethylammonium bromide solution in acetic acid (15mL) provided a solvent background correction. The epoxide and EEW percentages were calculated using the following equations:

% epoxide ═ x (0.4303)/(gram sample titration) [ (ml titration sample) - (ml titration blank) ]

EEW 43023/[% epoxide ]

It will be apparent to those skilled in the art that the above description of specific embodiments of the invention is not intended to limit the application of the invention, and that various equivalents and modifications may be made thereto depending on the circumstances. All such substitutions and modifications are intended to be within the scope of the appended claims without departing from the spirit of the invention.