VPS 4721 – A Novel Epoxy Functional Silane Resin for Polymer Dispersions

2

VPS 4721 is a novel high molecular weight epoxy functional silane which can be used in different applications. It has some advantages due to the high molecular weight compared to standard epoxy silane. The advantages are summarized in the following chart.

There is a market need for additives which can improve the performance of acrylic polymer dispersions. A standard epoxy silane is such an additive which can be used in acrylic polymer dispersions, but the disad-vantage is the shelf life of such formulations. Stable one-component acrylic dispersions with a standard

High molecular weight

Colorless

Stable epoxy resin

Performance in formulations

■ Advantageous labeling compared to a standard epoxy silane

■ Applications for color sensitive coatings and adhesives

■ Long-term stability

■ Better stability in polymer dispersions

■ More than 60 % less VOC compared to a standard epoxy silane

■ High quality product

■ Excellent reactivity

■ Better adhesion on substrates, less water uptake

1

3

2

4

epoxy silane are very challenging to achieve. Many parameters are influencing the stability of coating formulations like pH and even inter-actions with other components. VPS 4721 can replace a standard epoxy silane and can be formulated with acrylic polymer dispersions resulting in a much better shelf life.

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In the following graph the shelf life of a pure acrylic polymer dispersion is compared with an acrylic polymer dispersion containing a standard epoxy silane or VPS 4721 as an additive.

VPS 4721 has a much better shelf life when added to a polymer dispersion

Immediately

0

50

100

MowilithLDM 7719

Solid

MowilithLDM 7719

+ 3 % standard

epoxy silane

MowilithLDM 7719

+ 3 %VPS 4721

MowilithLDM 6119

MowilithLDM 6119

+ 3 % standard

epoxy silane

MowilithLDM 6119

+ 3 % VPS 4721

150

250

200

2 weeks at RT 4 weeks at RT 8 weeks at RT

Visc

osity

/ D

IN 4

cup

/ s

Stability of VPS 4721 compared to a standard epoxy silane in a 1 comp. acrylic dispersions.

4

The shelf life of a formulation is important for the marketing of a coating. Acrylic polymer dispersions containing VPS 4721 have a better shelf life compared to formulations with a standard epoxy silane without any disadvantages in the perfor-mance. One important parameter for a coating is the water uptake. The water uptake of a coating based on an acrylic polymer dispersion can e. g. reduce the scrub resistance and

without silane

0

20

10

30

Mowilith LDM 7719(Celanese)

53

33

1.5 1 11

Mowilith LDM 6119(Celanese)

40

60

50

+ 3 % standard epoxy silane + 3 % VPS 4721

Wat

er u

ptak

e / %

the weathering stability. If VPS 4721 is used as an additive, a good shelf life combined with less water uptake can be achieved. The Figure below demonstrates the water uptake of pure polymer dispersions compared with polymer dispersions containing a standard epoxy silane or VPS 4721. VPS 4721 shows the same perfor-mance as a standard epoxy silane.

Water uptake of pure polymer dispersions with silanes after 24 hours water immersion

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The stability of a formulation depends on the components. Interactions of the components can reduce the shelf life. Therefore the shelf life of formulations with differ-ent components has to be tested for each formulation.

Comp. A Supplier p.b.w.

DI water ./. 7.7

NaOH 10 % ./. 0.3

TEGO® Dispers 711W Evonik 1.0

TEGO® Foamex 20 Evonik 0.2

TEGO® ViscoPlus 3030 Evonik 0.8

TiO2 Kronos 2310 Kronos 19.0

Millicarb® OG Omya 13.5

Mica MKT Imerys 2.5

DI water ./. 3.0

Mowilith® LDM 7719 Celanese 50.0

Dowanol DPnB Dow Chemical 1.0

Silane Evonik 1.0

Total 100

Formulation 1 1-pack dispersion paint for wood coating – based on guiding formulation L5026 HAI from Celanese

Two different standard formulations for a wood coating were used and formulated pure and with a standard epoxy silane and VPS 4721. The standard formulations are summarized in the following Tables 1 and 2.

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The shelf life of formulations can also be tested at higher tempera-tures. The higher temperature will accelerate the aging, and effects can be seen after a shorter time.

The test results of the shelf life of the example Formulations 1 and 2, pure and with a standard epoxy silane or VPS 4721, are shown on the next page.

Comp. A Supplier p.b.w.

DI water ./. 14.8

Tylose® MH 4000 KG 4 Shin-Etsu 0.2

TEGO® Foamex 26 Evonik 0.3

TEGO® Dispers 711 W Evonik 1.5

NaOH 10 % ./. 0.2

TiO2 Kronos 2160 Kronos 22.0

Millicarb® OG Omya 15.0

Talco Extra Blanco Minerals i Derivats 5.5

NaOH 10 % ./. 0.2

Mowilith® LDM 6119 Celanese 38.5

TEGO® ViscoPlus 3030 Evonik 0.8

Silane Evonik 1.0

Total 100

Formulation 2 1-pack dispersion paint for interior and exterior – based on guiding formulation L3037 HAI from Celanese

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Stability of 1 comp. polymer dispersion paints containing a standard epoxy silane and VPS 4721

Formulation 1 is stable at 50 °C and no change in viscosity can be observed. Formulation 1 with 1 % (w/w) standard epoxy silane as an additive is not stable. The viscosity is increasing after a storage time of one week from 30 sec to 200 sec and after 2 weeks to 300 sec. Formulation 1 with 1 % VPS 4721 does not change the viscosity after one or two weeks.

Immediately

0

50

100

Example 1

Formulation 1 Formulation 2

Example 1+ 1 %

standard epoxy silane

Example 1+ 1 %

VPS 4721

Example 2 Example 2+ 1 %

standard epoxy silane

Example 2+ 1 %

VPS 4721

150

250

300

200

1 week at 50 °C 2 weeks at 50 °C

Visc

osity

/ D

IN 4

cup

/ s

Formulation 2 without a standard epoxy silane or VPS 4721 is not stable as the viscosity is increasing at a storage temperature of 50 °C after one and two weeks. A similar picture can be seen for the formulation 2 containing 1 % (w/w) standard epoxy silane. The viscosity is increas-ing from 50 sec to 300 sec after a storage time of 2 weeks. If these results are compared with formulation 2 containing VPS 4721 a moderate viscosity increase from 50 sec to 70 sec can be observed.

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Water uptake

without silane

0

1210

14

Example 1

17.5

Example 2

16

2018

24

86

+ 3 % standard epoxy silane + 3 % VPS 4721

Wat

er u

ptak

e / %

15.5

8.3 9.4

13.9

9.1

The water uptake of the coatings based on formulation 2 show less water uptake for the formulations containing standard epoxy silane or VPS 4721.

Water uptake of 1 comp. dispersion paints

The water uptake of the coating based on formulation 1 and 2 with-out and with a standard epoxy silane or VPS 4721 are compared in the figure below. Coatings based on the pure formulation 1 and formulation 1 with 3 % standard epoxy silane are having a much higher water uptake compared to the coating based on formulation 1 with 3 % (w/w) VPS 4721.

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Improvement of weathering-resistance of epoxy coatings

Component A Amount %

Ancarez® 4010 / D.E.R. 3531 (liquid DGEBA, EEW=190) 62.2

Epodil® 748 (EEW=290) 13.8

TiO2 (Kronos 2310) 20.8

TEGO® Dispers 670 2.6

TEGO® Wet 240 0.6

Total 100

Component B Amount %

Ancamine® 2280 (H-active EQ = 110) 100

Component A Component B

Mixture ratio 100 42

The weathering stability of epoxy coatings is usually limited. In many outside applications an additional weathering stable top coat has to be applied on the epoxy coating. A lot of developmental work was done at different places to improve the weathering stability of epoxy coatings. Silane based additives

were tested in epoxy coatings and in many cases the weathering stability was improved. The following test results show an epoxy coating formulation with a standard epoxy silane and VPS 4721 as an additive. The weathering resistance was measured via the gloss of the coating with the weathering time.

The composition of the epoxy coating:

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The results of the weathering tests are shown in the following figure:

The gloss is decreasing for the pure epoxy coating formulation and for the formulation with 10 % standard epoxy silane from 100 % to 33 % versus 34 % after 450 hours and 24 % versus 22 % after 900 hours in the weathering test. The epoxy coating formulation containing 10 % of VPS 4721 has a reduction in the gloss from 100 % to 84 % after 450 hours and 77 % after 900 hours in the weathering test.

Initial

0

6050

70

0-Reference 10 % standard epoxy silane 10 % VPS 4721

80

10090

1020

4030

450 h 900 h

Glo

ss 8

5 °

Gloss QUV-B Test at 85 °/ %

3324

100

34

22

10084

77

100

These test results show an improve-ment in the weathering bahavior through additivation with VPS 4721 in comparison to a standard epoxy silane.

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Contact Adhesives & Sealants Dr. Thomas Schlosser Phone +49 7623 91-8392 thomas.schlosser@evonik.com Jürgen Fritz Phone +49 7623 91-8592 juergen.fritz@evonik.com

Coatings Dennis Bringmann Phone +49 7623 91-8188 dennis.bringmann@evonik.com

Please scan the QR code or visit our website: www.dynasylan.com

Please scan the QR code or visit our website: www.aerosil.com

EVONIK OPERATIONS GMBH Silanes Business Line Rodenbacher Chaussee 4 63457 Hanau Germany dynasylan@evonik.com https://www.dynasylan.com/product/ dynasylan/en/contact/

This information and any recommendations, technical or otherwise, are presented in good faith and believed to be correct as of the date prepared. Recipients of this information and recommendations must make their own determination as to its suitability for their purposes. In no event shall Evonik assume liability for damages or losses of any kind or nature that result from the use of or reliance upon this information and recommendations. EVONIK EXPRESSLY DISCLAIMS ANY REPRESENTATIONS AND WARRANTIES OF ANY KIND, WHETHER EXPRESS OR IMPLIED, AS TO THE ACCURACY, COMPLETENESS, NON-INFRINGEMENT, MERCHANTABILITY AND/OR FITNESS FOR A PARTICU-LAR PURPOSE (EVEN IF EVONIK IS AWARE OF SUCH PURPOSE) WITH RESPECT TO ANY INFORMATION AND RECOMMENDATIONS PROVIDED. Reference to any trade names used by other companies is neither a recommendation nor an endorsement of the corresponding product, and does not imply that similar products could not be used. Evonik reserves the right to make any changes to the information and/or recommendations at any time, without prior or subsequent notice. Dynasylan® is a registered trademark of Evonik Industries AG or one of its subsidiaries.

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