Eastman Optifilm™ enhancer 400and Eastman Texanol™ ester alcohol vs.BASF Loxanol™ CA 5320* for architectural coatings

Architectural coatings present challenging formulation problems. Although a coalescent improves film formation, it can be a major contributor of VOCs in architectural coatings. For a coalescent to be used in an architectural paint, it must not only be compatible with the film-forming latex but also with other components in the paint formula. Low- and zero-VOC coalescents are being launched into the market to help meet VOC regulations and maintain the physical properties of paint.

This study demonstrates the effects on physical properties of two paint formulations when Eastman Texanol™ ester alcohol or Eastman Optifilm™ enhancer 400 is used vs. BASF Loxanol™ CA 5320. The study further demonstrates that the coalescent efficiency is affected by the type of latex used in the paint.

Conclusion • There is a potential cost savings from using up to 50% less coalescent in the paint with Optifilm 400 and Texanol than with Loxanol CA 5320 in acrylic latex paints. It was demonstrated that Optifilm 400 and Texanol are more efficient than Loxanol CA 5320 in the Dow Rhoplex™ SG-10M semigloss paint evaluated.

• The efficiency of Optifilm 400 is equivalent to Loxanol CA 5320 in BASF Acronal Optive® 230.

• Optifilm 400 and Texanol have the potential of improving the paint workability when compared with Loxanol CA 5320. This study revealed that Optifilm 400 and Texanol improved the open time of Rhoplex SG-10M semigloss paint when compared with Loxanol CA 5320.

• Optifilm 400 and Texanol can improve the applied paint appearance when compared with Loxanol CA 5320. The semigloss paint evaluated with Optifilm 400 and Texanol has an improved flow and leveling when compared with Loxanol CA 5320.

• Optifilm 400 and Texanol offer shorter return-to-service times than Loxanol CA 5320 in the Rhoplex SG-10M formulas. The semigloss paints formulated with Optifilm 400 and Texanol would allow doors and windows to be closed without sticking sooner than the formula with Loxanol CA 5320 due to superior block resistance.

DataTwo water-based architectural paints were formulated to study the effect of a coalescent in paint application properties. A semigloss acrylic interior paint and a flat acrylic interior paint were evaluated in this study.

The comparison shows the following:

• The coalescent efficiency in paints is affected by the type of latex.

• Physical paint application properties such as open time, flow and leveling, scrub resistance, block resistance, and colorant compatibility are affected by the type of coalescent in the paint.

• When the coalescent is changed in the paint, rheology modifier adjustment may be required to obtain good flow and leveling properties.

Minimum film formation temperature (MFFT) characteristics were determined for Texanol, Optifilm 400, and Loxanol CA 5320 with Rhoplex SG-10M acrylic latex and Acronal Optive 230 acrylic latex.

The results in the acrylic Rhoplex SG-10M at an MFFT of 40°F showed that Loxanol CA 5320 is 100% less efficient than Optifilm 400 and Texanol.

*Formerly Cognis Loxanol™ EFC-200

The paints with Optifilm 400 and Texanol had an improved flow and leveling when compared to Loxanol CA 5320 in the acrylic Rhoplex SG-10M semigloss paints. (See Figure 3.) No major flow and leveling differences were observed in Acronal Optive 230 acrylic flat paints with different coalescents. (See Figure 4.)

Figure 3. Rhoplex SG-10M acrylic semigloss paint flow and leveling

Figure 4. Acronal Optive 230 acrylic flat paint flow and leveling

Block resistance is the ability of paint, when applied to two surfaces, not to stick to itself on contact when pressure is applied. One of the challenges of low-VOC coatings is simultaneously attaining smooth film formation and acceptable block resistance. Low-quality latex paints generally have poor block resistance.

The block resistance results show the effect of formulating with different coalescing aids (Figures 5 and 6). In the case of Texanol in Rhoplex SG-10M acrylic semigloss paint, the block resistance remained constant over time. It is also notable that the Rhoplex SG-10M acrylic semigloss paint with Loxanol CA 5320 did not improve over time as expected.

Figure 5. Rhoplex SG-10M acrylic semigloss paint block resistance

Figure 1. Rhoplex™ SG-10M MFFT

Figure 2. Acronal Optive® 230 MFFT

Acronal Optive® 230 is also an acrylic latex with a lower Tg than that of Rhoplex™ SG-10M (6° vs. 16°C). The amount of coalescent needed to lower the MFFT at 40°F is very low due to the softness of the latex. Eastman Optifilm™ enhancer 400 and Loxanol CA 5320 are 100% less efficient than Eastman Texanol™ ester alcohol.

It was determined that it is more accurate to measure the coalescent efficiency in paint. In general, an additional 10% of the coalescent concentration needed to obtain an MFFT at 35°F of latex was used in the final formulations to obtain a good film formation at 40°F.

All the paints were thickened to constant Stormer and ICI viscosities with low- and high-shear synthetic associative rheology modifiers. The sag and leveling properties in architectural paints are generally controlled with rheology modifiers. A good quality semigloss paint should have a leveling of at least 7 and a sag resistance of at least 12 mils. In a good flat paint, an acceptable sag resistance is 16 mils, whereas the leveling could be as low as 4.

65

Χ

ΧΧ

Χ

0 2 10864 12

phr

MFF

T, °

F

65

30

35

40

45

50

55

60

25

Χ Texanol

Loxanol CA 5320Optifilm 400

Χ

ΧΧ

ΧΧ

Χ Texanol

Loxanol CA 5320Optifilm 400

MFF

T, °

F

45

30

35

40

0 0.5 2.521.51 3.5

phr3

Leveling

30

5

0

10

15

20

25

Texanol Optifilm 400 LoxanolCA 5320

Sag, milsLeveling

Sag

resi

stan

ce (m

ils)

−10

−9

−4

−6

−7

−8

0

−1

−2

−3

−5

30

5

0

10

15

20

25

Texanol Optifilm 400 LoxanolCA 5320

Sag, milsLeveling

Sag

resi

stan

ce (m

ils)

Leveling

−10

−9

−4

−6

−7

−8

0

−1

−2

−3

−5

12

2

0

4

6

8

10

Texanol Optifilm 400 LoxanolCA 5320

Bloc

k re

sist

ance

24 h RT, 60 min

72 h RT, 30 min @ 50°C

1 wk RT, 30 min @ 50°C

Figure 8. Acronal Optive 230 acrylic flat paint scrub resistance

Open time is the length of time a coating remains wet enough to allow for brushing in at the laps. In latex paints, the open time is affected by the total VOC content of the paint. In the Rhoplex™ SG-10M acrylic semigloss paint, Eastman Texanol™ ester alcohol had the longest open time and Loxanol CA 5320 had the shortest open time (5 and 3 minutes respectively). (See Figure 9.) In Acronal Optive® 230 paints, the open time/wet-edge was similar for Eastman Optifilm™ enhancer 400, Texanol, and Loxanol CA 5320. (See Figure 10.)

Figure 9. Rhoplex SG-10M acrylic semigloss paint open time/wet edge

Figure 10. Acronal Optive 230 flat paint open time/wet edge

Texanol Optifilm 400 LoxanolCA 5320

Scrub 7 days

Scrub 8 weeks1600

0

200

400

600

800

1000

1200

1400

Scru

b re

sist

ance

Figure 6. Acronal Optive 230 acrylic flat paint block resistance

Table 1. Block resistance ratings, ASTM D-4946

Numerical rating

Type of separation Performance

10 No tack Perfect

9 Trace tack Excellent

8 Very slight tack Very good

7 Very slight to slight tack Good to very good

6 Slight tack Good

5 Moderate tack Fair

4 Very tacky, no seal Poor to fair

3 5%–25% seal Poor

2 25%–50% seal Poor

1 50%–75% seal Very poor

0 75%–100% seal Very poor

Semigloss paints have superior scrub resistance compared with flat paints because of the higher pigment-to-binder ratio in the semigloss paints. All the paints evaluated showed a significant improvement in scrub resistance after the samples were aged for several weeks. The scrub resistance results must differ by at least 200 scrub cycles to be considered significantly different. No major differences in scrub resistance were observed on aged coatings.

Figure 7. Rhoplex SG-10M acrylic semigloss paint scrub resistance

12

2

0

4

6

8

10

Texanol Optifilm 400 LoxanolCA 5320

Bloc

k re

sist

ance

24 h RT, 60 min

72 h RT, 30 min @ 50°C

1 wk RT, 30 min @ 50°C

Texanol Optifilm 400 LoxanolCA 5320

Scrub 7 days

Scrub 8 weeks1600

0

200

400

600

800

1000

1200

1400

Scru

b re

sist

ance

Texanol Optifilm 400 LoxanolCA 5320

Open time

Wet edge

0

1

2

3

4

5

6

7

Min

utes

Texanol Optifilm 400 LoxanolCA 5320

Open time

Wet edge

0

1

2

3

4

5

6

7

Min

utes

Color development relates to the color strength of the tinted paint film. Full color development is essential to economical tinting and good application properties. Color acceptance is defined as the compatibility, distribution, and stability of the colorant in the paint. Color acceptance is determined by rubbing up the wet film. With this test, pigment flocculation can be assessed. In this study, color development and color acceptance of the paints were evaluated by tinting paint samples at 2 fl oz/gal with BASF Options Red Oxide and Options Phthalo Blue colorants.

Very poor color acceptance was observed in the Rhoplex™ SG-10M paint with Loxanol CA 5320 tinted with Red Oxide and Phthalo Blue. (See Figures 11 and 12.)

Figure 11. Rhoplex SG-10M acrylic semigloss paint (Red Oxide)

Figure 12. Rhoplex SG-10M acrylic semigloss paint (Phthalo Blue)

Optifilm 400 Loxanol CA 5320

Table 2. Summary of paint application properties with Texanol (Performance as compared to Texanol)

Loxanol CA 5320 (coalescent)

Application properties

Rhoplex SG-10M

(latex)

Acronal Optive 230

(latex)

Coalescent efficiency −100% −100%

Leveling <<< =

Block resistance <<< <<

Scrub resistance > =

Open time/wet edge << =

Color development <<< =

< Lower performance> Improved performance= Equivalent performance−100% Twice as much coalescent is needed for the latex to properly coalesce.

Table 3. Summary of paint application properties with Optifilm 400 (Performance as compared to Optifilm 400)

Loxanol CA 5320 (coalescent)

Application properties

Rhoplex SG-10M

(latex)

Acronal Optive 230

(latex)

Coalescent efficiency −100% =

Leveling <<< =

Block resistance <<< <<

Scrub resistance > =

Open time/wet edge < =

Color development <<< =

< Lower performance> Improved performance= Equivalent performance−100% Twice as much coalescent is needed for the latex to properly coalesce.

AppendixCoalescent physical properties

Physical properties Texanol Optifilm 400 Loxanol CA 5320

Solubility, wt% In water, @ 20°C Water in, @ 20°C

0.13.0

0.00.9

1.730.04

Boiling point @ 760 mmHg

254°C 374°–381°C 320°C

% VOC 110°C for 1 hour

100 0.7 2

Optifilm 400 Loxanol CA 5320

COAL-COAT-057 12/15

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