FIRE-PROTECTION COATING COMPOSITION AND USE THEREOF

Abstract

A composition for an intumescent coating contains a binder system and an intumescent composition. The binder system contains an alkoxy-functional organic polymer, which contains an alkoxy-functional silane group; and a styrene-acrylate copolymer. The composition is useful as a coating, in particular a fire-protection coating.

Claims

1: A fire-protection composition for an intumescent coating, comprising: (A) a binder system, comprising (a1) an alkoxy-functional organic polymer, which contains an alkoxy-functional silane group having the general formula (I), terminated and/or as a side group along a polymer chain,
Si(R.sup.1).sub.m(OR.sup.2).sub.3-m(I), in which R.sup.1 represents a linear or branched C.sub.1-C.sub.16 alkyl group, R.sup.2 represents a linear or branched C.sub.1-C.sub.6 alkyl group, and m is a whole number from 0 to 2; and (a2) a styrene-acrylate copolymer; and (B) an intumescent composition.

2: The fire-protection composition according to claim 1, wherein the alkoxy-functional organic polymer (a1) comprises a basic skeleton, which is at least one member selected from the group consisting of an alkyl chain, a polyether, polyester, polyether ester, polyamide, polyurethane, polyester urethane, polyether urethane, polyether ester urethane, polyamide urethane, polyurea, polyamine, polycarbonate, polyvinyl ester, polyacrylate, poly olefin, polyisobutylene, polysulfide, natural rubber, neoprene, phenolic resin, epoxy resin, and melamine.

3: The fire-protection composition according to claim 2, wherein the basic skeleton is the polyether or the polyurethane.

4: The fire-protection composition according to claim 1, wherein the alkoxy-functional organic polymer (a1) contains at least 2 alkoxy-functional silane groups.

5: The fire protection composition according to claim 1, wherein the styrene-acrylate copolymer is derivable by polymerization of a monomer mixture comprising one or more alkyl (meth)acrylate monomers, and one or more optionally substituted styrene comonomers.

6: The fire protection composition according to claim 1, wherein the styrene-acrylate copolymer is derivable from a monomer mixture comprising greater than or equal to 30 wt % and less than or equal to 60 wt. % of one or more alkyl (meth)acrylate comonomers, and greater than or equal to 40 wt. % and less than or equal to 70 wt. % of one or more optionally substituted styrene comonomers.

7: The fire protection composition according to claim 5, wherein the one or more alkyl (meth)acrylate monomers comprises one or more C.sub.1 to C.sub.12 alkyl (meth)acrylates.

8: The fire protection composition according to claim 5, wherein the one or more optionally substituted styrene comonomers are one or more selected from the group consisting of unsubstituted styrene and C.sub.1 to C.sub.6 alkyl substituted styrene.

9: The fire protection composition according to claim 1, wherein a total amount of polymeric compounds is 10 to 40 wt.-%, with reference to a total weight of the fire protection composition.

10: The fire protection composition according to claim 1, wherein the styrene-acrylate copolymer is present in an amount of greater than or equal to 3 wt. % and less than or equal to 15 wt. %, based on a total weight of the fire protection composition.

11: The fire protection composition according to claim 1, wherein a ratio of the alkoxy-functional organic polymer to the styrene-acrylate copolymer is 0.1:1 to 10:1.

12: The fire protection composition according to claim 1, wherein the intumescent composition (B) comprises at least one compound selected from the group consisting of a dehydrogenation catalyst, a propellant, a carbon supplier, an organic filler, an inorganic filler, a thermally expandable compound, and a mixture of two or more compounds thereof.

13: The fire protection composition according to claim 12, wherein the intumescent composition (B) comprises a combination of the dehydrogenation catalyst, the propellant, and the carbon supplier.

14: The fire protection composition according to claim 1, wherein the fire protection composition additionally comprises (C) a further filler.

15: The fire protection composition according to claim 1, wherein the fire protection composition additionally comprises (D) a further additive.

16: (canceled)

17: The fire protection composition according to claim 1, wherein the fire protection composition is a two-component composition with a first component and a second component.

18: The fire protection composition according to claim 17, wherein the first component contains the alkoxy-functional organic polymer (a1), and the second component contains the styrene-acrylate copolymer (a2) and the intumescent composition (B).

19: The fire protection composition according to claim 18, wherein the first component and/or the second component additionally contain a further filler (C) and/or a further additive (D).

Description

COMPARATIVE EXAMPLES

Comparative Example 1

[0129] Comparative Example 1 is based on example 2 of WO 2010/131037 A1, however, without additives and plasticizer to better show the inventive effect. The formulation is based on an alkoxysilane-based polymer as the only polymer. The weight lost by the omission of plasticizers and additives is compensated by the silane-terminated prepolymer/crosslinker blend so that the end film has the same filling content. The formulation of Comparative Example 1 is shown in Table 1.

Comparative Example 2

[0130] Based on Comparative Example 1 a formulation with one plasticizer was prepared. The formulation of Comparative Example 2 is also shown in Table 1.

Comparative Example 3

[0131] Also based on Comparative Example 1 a formulation with one plasticizer but without a crosslinker was prepared. The formulation of Comparative Example 3 is also shown in Table 1.

Comparative Example 4

[0132] Also based on Comparative Example 1 a formulation but without a crosslinker and without a plasticizer was prepared. The formulation of Comparative Example 4 is also shown in Table 1.

Examples 1 to 6

[0133] To show the positive influence of the styrene-acrylate copolymer added to a crosslinker-free and plasticizer-free MS-Copolymer based formulation the formulation of Comparative Example 3 was selected as the base formulation. The plasticizer was replaced by different amounts of styrene-acrylate copolymer as shown in Table 1 (Examples 1 to 5). To show that alternative styrene-acrylate copolymers can be used, the styrene-acrylate copolymer of Example 5 was replaced by a different one (Example 6).

[0134] Specimen were prepared from all Comparative Example 1 to 4 formulations and from Example 1 to 6 formulations and the following coating properties and fire performance were determined:

[0135] Coating Properties: [0136] Shore D hardness after 1 week at 45 C. [0137] Film aspect after 1 week at 45 C. (1.5 mm WFT) [0138] Bond strength (pull off adhesion test)

[0139] The Shore D hardness was determined with specimen by letting specimen (draw down panels) at 1.5 mm wet film thickness (WFT) dry for one week at 45 C., whereas the hardness of the hardened mass was the depth of penetration of a spring-loaded pin in the material with a Shore durometer (DIN-ISO 7619). The Shore D hardness is measured with a rod that has a tip with a conical point having a radius of 0.1 mm and an opening angle of 30 degrees; the applied mass is 5 kg and the holding time is 15 seconds. The results are shown in table 2.

[0140] The flat surface aspect or film aspect was determined applying a coat of 1.5 mm WFT (1 mm DFT approximately) over a primed steel panel and leaving it drying over a period of 1 week (seven days) at 45 C. The results are also shown in Table 2.

[0141] Pull off adhesion tests to evaluate the bond strength were carried out following ISO 4624. The test determines the greatest perpendicular force (in tension) that a surface area can bear before a plug of material is detached. Failure will occur along the weakest plane within the system comprised of the test, that is adhesive, intumescent coating, primer and steel substrate, and will be exposed by the fracture surface. Four failure modes can occur (1) adhesive failure between primer and steel, (2) adhesive failure between primer and intumescent coating, (3) cohesive failure of the intumescent coating, i.e. failure happens within the intumescent coating, (4) adhesive failure between intumescent coating and plug. The breaking of the system by the pull off adhesion test tends to be not 100% of one failure mode, but often is a mixture or combination of two failure modes, whereas the percentage indicates the degree of each failure mode. The results of the pull off adhesion test, i.e. the achieved load to failure, and the results of a visual assessment of the failure mode are shown in Table 3.

[0142] Panel Fire Performance Properties: [0143] Time to failure (Table 4) [0144] Char properties (Table 5)

[0145] Time to failure (TTF): For the fire performance evaluation a primed and grit blasted carbon steel panel (5 mm thickness; 280 mm width; 280 mm width) was coated at 2 mm dry film thickness (DFT) with the intumescent coatings according to comparative Examples 1 to 4 and Examples 1 to 6 shown in Table 1. It is let to dry and cure for at least two weeks at ambient temperature. The fire test is carried out in a gas fueled furnace following the ISO 834 fire curve and the temperature at the core of the steel panel is monitored by three thermocouples type K. The time to failure is the time for the carbon steel panel to reach an average temperature of 538 C., also abbreviated as TTF538. The results are shown in Table 4.

[0146] Char properties: Once the panel reaches 538 C. average temperature the furnace is stopped and cooled down to room temperature as quickly as possible using ventilation. Once the panel reached room temperature its char is analysed by visual inspection to find the characteristics of its expansion. The results of the inspection are also shown in Table 4.

TABLE-US-00002 TABLE 1 Formulations of Comparative Examples 1 to 4 and Examples 1 to 6 Compar- Compar- Compar- Compar- ative ative ative ative Example 1 Example 2 Example 3 Example 4 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Compound wt.-% MS-Copolymer 20.18 8.25 9.20 21.13 9.20 14.69 17.69 12.68 15.85 14.69 MS-Crosslinker 0.95 0.95 Plasticizer 11.93 11.93 Styrene-acrylate 11.93 6.44 3.44 8.45 5.28 copolymer 1 Styrene-acrylate 6.44 copolymer 2 Xylene 16.59 16.59 16.59 16.59 16.59 16.59 16.59 16.59 16.59 16.59 Mineral fibers 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 Titanium dioxide 10.58 10.58 10.58 10.58 10.58 10.58 10.58 10.58 10.58 10.58 Melamine 9.31 9.31 9.31 9.31 9.31 9.31 9.31 9.31 9.31 9.31 Pentaerythritol 9.31 9.31 9.31 9.31 9.31 9.31 9.31 9.31 9.31 9.31 Ammonium 28.37 28.37 28.37 28.37 28.37 28.37 28.37 28.37 28.37 28.37 polyphosphate China Clay 2.12 2.12 2.12 2.12 2.12 2.12 2.12 2.12 2.12 2.12 Garamite 1.67 1.67 1.67 1.67 1.67 1.67 1.67 1.67 1.67 1.67

TABLE-US-00003 TABLE 2 Results of the Shore D measurement and results of the assessment of the film aspect Example Shore D [Shore] Aspect Comparative 45 smooth Example 1 Comparative 25 slight cracking Example 2 Comparative 0 wet Example 3 Comparative 0 dry surface dry, not Example 4 cured with slight cracking surface cracks Example 1 63 smooth Example 2 45 smooth Example 3 45 smooth Example 4 55 smooth Example 5 52 smooth Example 6 45 smooth

[0147] The results in Table 2 show that the hardness of the dried film increases when an acrylic/styrene co-polymer instead of a plasticizer or crosslinker is used with the MS polymer system. The results lead to the conclusion that the styrene-acrylate copolymer acts as hardener like a crosslinker, also having a positive impact on the film formation.

TABLE-US-00004 TABLE 3 Results of the bond strength measurement Bond Failure Example strength (MPa) mode Comparative 1.86 100% cohesive failure within Example 1 intumescent coating Comparative 0.68 80% cohesive failure within Example 2 intumescent coating; 20% adhesive failure between primer and intumescent coating Comparative 0 predominantly adhesive failure Example 3 between primer and intumescent coating Comparative 0 adhesive failure, coating is Example 4 only surface dry. Example 1 0.79 80% adhesive failure between primer and intumescent coating; 20% cohesive failure within intumescent coating Example 2 1.9 100% cohesive failure within intumescent coating Example 3 0.5 100% cohesive failure within intumescent coating Example 4 4.6 70% adhesive failure between primer and intumescent coating; 30% cohesive failure within intumescent coating Example 5 4.2 100% cohesive failure within intumescent coating Example 6 2.7 100% cohesive failure within intumescent coating

[0148] The results in Table 3 show that the crosslinker-free formulation of comparative Example 3 did not allow the MS prepolymer to cure resulting in a negligible result. The high concentration of plasticizer in the formulation of Comparative Example 2 resulted in a decrease of bond strength. The results of Examples 1 to 6 show that the use of a styrene-acrylate copolymer in conjunction with an MS prepolymer provided curing and an average level of bond strength which can get as high as with the use of a crosslinker.

TABLE-US-00005 TABLE 4 Results of the time to failure (TTF538) measurement and results of the assessment of the char properties Example TTF538 (min) Char properties Comparative 23.9 Partial char detachment Example 1 Comparative 21.6 Partial char detachment Example 2 Comparative 31.9 Coating was partially Example 3 detached before fire test and the char detached during the fire test. Comparative 85.8 Nodular char, compact and Example 4 cohesive Example 1 71.6 Cohesive char Example 2 86.1 Very cohesive char Example 3 89 High expansion rate and cohesive Example 4 79.4 Controlled expansion and cohesive Example 5 68.7 Nodular and slightly cracked surface but cohesive Example 6 77.3 Compact and even expanded char with high cohesivity

[0149] According to the results shown in Table 4, the fire performance of the comparative examples was extremely poor due to char detachments from substrate. Contrary thereto, the formulations comprising the styrene-acrylate copolymer (Examples 1 to 6) show a significant improvement in the fire performance properties, in that the time to failure is prolonged which leads to longer insulation times, and the char properties are better.