Encouraging Innovation Environmental Regulations Drive Epoxy Formulation

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52 JPCL April 2015 / paintsquare.com

By Marcelo Rufo, Air Products and Chemicals, Inc.

A

ccording to Harvard Business School professor Michael Porter, in what has come to be known as the “Porter hypothesis,” strict environmental regulations can induce efficiency and encourage innovations that help improve commercial competitiveness.

Global environmental regulations have driven much devel-

opment in the coatings industry and regulations implemented to increase worker safety and environmental protection have helped to launch many new products. There is increasing social pressure on all industrial activities to reduce and or eliminate the use of raw materials that could have a negative impact on the environment and on the health of people consuming or handling products that use such raw materials. Several different terminologies have been used by the paint and coatings industry to describe the various technological solutions, such as “compliant” or “environmentally friendly,” “HAPs-free” (hazardous air pollutants), “water-based or water-reducible” and more recently “emissions-free” or “totally reactive technology.” The terms mentioned describe concerns being addressed and advantages and disadvantages of these new technologies against well-established products in the market. Typically the speed of adoption of new technologies by the coatings industry is linked with the development of new polymers or resins that will serve as a base for the new formulations addressing concerns about environmental regulations, while meeting stringent performance requirements.

paintsquare.com / JPCL April 2015 53

REGULATIONS & FORMULATION

Just few decades ago, a typical

tion, the United States Environmental

these two regions, it wouldn´t be diffi-

conversation between a development

Protection Agency (EPA) keeps a list of

cult to find the same paint sold in both,

chemist and a marketing professional

exempt organic compounds that have

but reporting different VOC numbers on

would probably be restricted to the

been identified as having negligible

its technical data sheet. Other countries

performance requirements for the new

photochemical reactivity. This concept

or regions might have different defini-

coating being developed. In today´s

allows paint companies in the U.S. mar-

tions for VOC, but these two are cited

world the performance of a new coating

ket to use exempt solvents to comply

as examples of how complex it can be

is just a starting point and further un-

with VOC regulations.

to achieve global compliance with VOC

derstanding of product registration, la-

The EPA set VOC limits for floor coat-

requirements.

beling, and volatile organic compound

ings at under 400 g/L, established under

Another factor of increasing impor-

(VOC) limits and definitions must also

rule 40 CFR 59, Subpart D — National

tance concerning VOC regulations is the

be addressed at the early stages of new

Volatile Organic Compound Emission

Green Building or Leadership in Energy

coating development. The challenge

Standards for Architectural Coatings

& Environmental Design (LEED) certifi-

becomes bigger as the world becomes

(issued in 1998). The Ozone Transport

cation program. A voluntary program,

smaller and today´s regulations may

Commission (OTC) whose current mem-

LEED provides third-party verification

have immediate impact on a global

bers include Connecticut, Delaware, the

of green buildings. Building projects

scale.

District of Columbia, Maine, Maryland,

satisfy prerequisites and earn points to

Probably the most significant impact

Massachusetts, New Hampshire, New

achieve different levels of certification.

of an environmental regulation came

Jersey, New York, Pennsylvania, Rhode

Prerequisites and credits differ for each

from the endeavor to reduce the VOCs

Island, Vermont and Virginia, uses 100

rating system, and teams choose the

in paints and coatings. This is still a

g/L for floor coatings and the South

best fit for the project.

very strong driver today and is likely to

Coast Air Quality Management District

In the case of epoxy coatings, the

be even more restrictive in the coming

(SCAQMD) uses 50 g/L for floors.

VOC requirement for floor coatings calls for less than or equal to 100 g/L in order

years. VOC Definition in Europe

to obtain the credits for LEED classifi-

Defining VOCs

In Europe the Solvent Emissions

cation. The challenge comes from the

When referring to coatings with low

Directive (SED), 1999/13/EC introduced

fact that most, if not all, of the so-called

VOC content, one must first understand

limits for volatile organic solvents from

solvent-free epoxy coatings quite often

the VOC definition specific to the region

an installation or stationary unit where

have a nonreactive plasticizer in their

where the coating will be used. For

a VOC was defined by its vapor pres-

composition. These plasticizers give the

example, the VOC definition used in the

sure at ambient temperature. Council

final coating the flexibility necessary to

United States is very different from that

Directive 2004/42/EC, also referred to as

meet industry requirements. The most

used in Europe.

the “Paints Directive,” specified a VOC

common nonreactive plasticizer used

by its boiling point at ambient pres-

is benzyl alcohol (BzOH). This normally

VOC Definition in the U.S.

sure and sets maximum limits of VOCs

results in a standard VOC content in

In the U.S., VOC refers to any com-

released into the environment for dif-

excess of 250 g/L, if the BzOH is classed

pound of carbon, excluding carbon

ferent types of coatings and varnishes.

as a volatile compound. Additionally, as

monoxide, carbon dioxide, carbonic

Under both directives, benzyl alcohol,

BzOH is classed as a fugitive plasticizer

acid, metallic carbides or carbonates,

which is the most widely used plasticiz-

(one that volatizes during the drying

and ammonium carbonate, which par-

er and modifier in epoxy curing agent

process) the coating can lose its flexi-

ticipates in atmospheric photochemical

technology, is considered a VOC.

bility over the service life as the BzOH

reactions. To supplement the defini-

Looking at the definitions within just

leaches out of the coating.

54 JPCL April 2015 / paintsquare.com

REGULATIONS & FORMULATION

Table 1: Properties and Performance of HPPA Based on Anticorrosive Primer Formulation

curing agent composition, properties such as low viscosity, good compatibil-

Anticorrosive Primer Formulation Based on HPPA

Formulation Based on Conventional Polyamide Adduct

VOC

g/L

85

320

Mix viscosity

mPa.s

1000

1000

still be achieved.

Mix solids

Vol. %

91

67

Typically, conventional, “solvent-free”

Mix ratio (by volume)

A:B

2:1

4:1

amine curing agents for epoxy coat-

Pot-life (min. to double viscosity)

77 F

90 - 120

120 - 150

ing may contain fugitive plasticizer in

Salt Spray*, 2000 hrs

Field/Scribe

10/9

10/9

Prohesion**, 2000 hrs

Field/Scribe

10/9

10/9

Adhesion GT 0, No blisters

Adhesion GT 0, No blisters

Cleveland Humidity*** 12 months

ity with epoxy resin, excellent carbamation resistance, excellent corrosion protection, and workable pot-life can

their composition ranging from 35 to 50 percent. This is not part of the final polymer network when the curing agent

*ASTM B-117, DFT ~200μm. Rating: ASTM D714, ASTM 1654: 10=Best, 0=Worst **ASTM G-85, DFT ~200 μm, Rating: ASTM D714, ASTM 1654: 10=Best, 0=Worst ***ASTM D-2247, cabinet temperature 60 C, Rating: Adhesion ISO 2409: GT 0=best, GT 5=worst

reacts with the epoxy resin and may leech out over time, impacting the film’s flexibility and changing the mechanical properties. The elimination of unreactive plasticizers which may be lost

Table 2: Properties of Conventional Modified Cycloaliphatic Amine Curing Agent and the New Amine Curing Agent (HPFA) Property Unit HPFA Modified Cycloaliphatic Amine Viscosity

mPa.s/77 F

150 - 250

300 – 600

Color

Gardner

≤4

≤3

Amine Equivalent Weight

95

95

Level of curing agent

phr*

50

50

Gel Time

Minutes/77 F

29

26

Degree of cure**

% @ 7 days

100

100

Level of fugitive plasticizer

%

0

25 – 50%

VOC for the curing agent only

g/L

0

412

VOC for curing agent plus epoxy resin

g/L

0

169

*Diluted Bisphenol-A/F resin, C12-14-glycidyl ether diluted, EEW 190, = 900 mPa.s **Determined by differential scanning calorimetry (DSC) at 10 C/min.

during the coating’s lifespan, facilitates long-term conservation of the mechanical properties of the coating. HPPA and HPFA The first experiment performed was the development of a high-performance polyamide curing agent (HPPA) using novel amine technology which was benchmarketed against a conventional polyamide. The results demonstrate similar corrosion protection with additional benefits including the elimination of the induction time and a significant reduction in viscosity while increasing the solids and elimination of the fugitive plasticizer.

Novel Amine Technology

agents do not contain fugitive plasticizer

Polyamide HPPAs were also formulat-

in Epoxy Coatings

in their composition.

ed in a high-solids, low-VOC, anticorro-

A classic approach to addressing VOC

A novel amine technology has been

sion primer and evaluated in accelerat-

regulations and reducing emissions in

developed for use in a new class of

ed weathering tests. The results showed

epoxy coatings is the adoption of water-

amine curing agents allowing fugitive

excellent anticorrosion properties with

borne technologies. In these systems,

plasticizers and solvents to be reduced

minimal or no failures up to 2,000 hours

conventional solvents are replaced by

or eliminated. Although solvents and

in salt spray and prohesion tests, and

water and typically, water-based curing

plasticizers can be removed from the

Cleveland humidity resistance of more

56 JPCL April 2015 / paintsquare.com

paintsquare.com / JPCL March 2015 57

REGULATIONS & FORMULATION

than a year without any loss of adhesion

it is possible to replace nonreactive

References

or blister formation (Table 1, p. 56).

plasticizers and solvents in formula-

A second experiment was carried out

tions without sacrificing application and

using the novel technology to develop

coating performance properties. New

an amine curing agent (HPFA) for floor-

curing agents can better position paint

ing application and an existing conven-

formulations for long-term viability as

tional modified cycloaliphatic amine

environmental regulations continue to

was used as a benchmark.

develop and become more restrictive on

As seen in Table 2 (p. 56), the key han-

coating composition.

Ambec, Stefan, Mark A. Cohen, Stewart Elgie and Paul Lanoie. “The Porter Hypothesis at 20: Can Environmental Regulation Enhance Innovation and Competetiveness?” Resources for the Future, Vol. 11, No. 1 (2011). “Biomonitoring: Bisphenol-A.” America’s Children and the Environment, Third Edition (ACE3). U.S. Environmental Protection Agency (EPA), June 20, 2013. http://www.epa.gov/ace/ biomonitoring/bpa.html. Frakes, Kyle. “VOC Regulations: Past, Present, and Future.” CoatingsPro, Vol. 10, No. 5 (September 2010). Le Craz, Sebastien and Richard A. Pethrick. “Solvent Effects on Cure 1-Benzyl Alcohol on Epoxy Cure.” International Journal of Polymeric Materials, Vol. 60 (2011). Lee, Henry and Neville, Kris. Handbook of Epoxy Resins. First Edition. McGraw-Hill Inc., October 1967. Ma, Songqi, Xiaoqing Lio, Libo Fan, Yanhua Jiang, Lijun Cao, Zhaobin Tang and Jin Zhu. “Sythesis and Properties of a Bio-Based Epoxy Resin with High Epoxy Value and Low Viscosity.” ChemSusChem, Vol. 7, No. 2 (February 2014). Porter, Michael E., and Claas van der Linde. “Green and Competetive: Ending the Stalemate.” Harvard Business Review, Vol. 73, No. 5 (September–October 1995). Rasing, Rob and Gamini A. Vedage. “Epoxy Systems: Clearing the Air.” European Coatings Journal, Vol. 11, No. 6 (June 2011). Totev, Daniel, G.A. Vedage, Willy Raymond, Marcelo Rufo, Mike Cook and Neil McFerran. “High-Performance Polyamide Curing Agents Offering Low Emissions and Long-Term Performance.” 20th SLF Conference (Federation of Scandinavian Paint and Varnish Technologists), Helsinki, May 2012. “VOC Solvents Emissions Directive.” Europe an Commission, March 20, 2015. http:// ec.europa.eu/environment/archives/air/ stationary/solvents/exchange.htm. Weiss, Keith D. “Paint and Coatings: A Mature Industry in Transition.” Progress in Polymer Science, Vol. 22, No. 2 (1997).

dling properties are very similar for the

Attributes such as low emission,

HPFA curing agent and for the commer-

the elimination of fugitive plasticizer

cially available cycloaliphatic amine, with

reducing or eliminating the VOC from

the advantage of the complete elimina-

the paint formulation, and the mainte-

tion of the fugitive plasticizer in the com-

nance of important properties such as

position of HPFA. As a result, significant

excellent corrosion protection, make the

reduction in the VOC level was observed

newly developed amine technology a

while the handling viscosity was main-

viable option for companies looking for

tained in the industry-acceptable range

innovative approaches to address the

for flooring applications.

stringent regulations around VOC con-

The technologies used in HPPA and

tent, while also aiding in the acquisition

HPFA offer the industry a means of

of Green Building certification.

satisfying VOC regulations without sacrificing coating properties.

About the Author Marcelo Rufo is the

Summary

senior application

The evolution of environmental regu-

chemist for the

lations is an ongoing process as new

coatings business

discoveries are made on the effects of

of Air Products and

existing chemicals. These discoveries

Chemicals, Inc.,

continue to drive discussion on the use

and is responsible

of these chemicals and the creation of

for the Americas region. His prima-

new regulations.

ry responsibilities are new product

Staying up-to-date with existing reg-

development, application development

ulations is mandatory and keeping an

and technical service related to curing

eye on evolving regulations can present

agents for epoxy coatings.

opportunities for leading companies to

Rufo has worked in the coatings

innovate.

industry for nearly 30 years, joining Air

These changes in environmental

Products and Chemicals, Inc. in 2000.

requirements present both challenges

His focus has always been research

and opportunities to paint formula-

and development of new products and

tors. Recent and ongoing curing agent

resins for coatings application.

developments have demonstrated that

58 JPCL April 2015 / paintsquare.com