POLYMER BLENDS FOR EPOXY RESINS COMPOSITIONS

Abstract

A curable epoxy resin composition including at least one epoxy resin, at least one inorganic filler and at least one dispersant, wherein the dispersant includes: (a) at least one first polymer, which is a comb polymer having a polymer backbone including acid groups and side chains which are linked to the polymer backbone, and (b) at least one second polymer, which is a condensate of, at least, an aromatic compound and formaldehyde; or a lignosulfonate.

Claims

1. A curable epoxy resin composition comprising at least one epoxy resin, at least one inorganic filler and at least one dispersant, wherein the dispersant comprises: a) at least one first polymer, which is a comb polymer having a polymer backbone comprising acid groups and side chains which are linked to the polymer backbone, and b) at least one second polymer, which is a condensate of, at least, an aromatic compound and formaldehyde; or a lignosulfonate.

2. The epoxy resin composition according to claim 1, wherein the inorganic filler is coated with the first polymer, the second polymer and/or the dispersant.

3. The epoxy resin composition according to claim 1 wherein the solvent is a polar organic solvent.

4. The epoxy resin composition according to claim 1, wherein the comb polymer comprises the following structural subunits: a) a mole fractions of a structural subunit S1 of the formula (I) ##STR00013## b) b mole fractions of a structural subunit S2 of the formula (II) ##STR00014## c) c mole fractions of a structural subunit S3 of the formula (III) ##STR00015## d) d mole fractions of a structural subunit S4 of the formula (IV) ##STR00016## where R.sup.1, in each case independently of any other, is COOM, SO.sub.2OM, OPO(OM).sub.2 and/or PO(OM).sub.2, R.sup.2, R.sup.3, R.sup.5, R.sup.6, R.sup.9, R.sup.10, R.sup.13 and R.sup.14, in each case independently of one another, are H or an alkyl group having 1 to 5 carbon atoms, R.sup.4, R.sup.7, R.sup.11 and R.sup.15, in each case independently of one another, are H, COOM or an alkyl group having 1 to 5 carbon atoms, M, independently of any other, is H.sup.+, an alkali metal ion, an alkaline earth metal ion, a di- or trivalent metal ion, an ammonium ion or an organic ammonium group, m is 0, 1 or 2, p is 0 or 1, R.sup.8 and R.sup.12, in each case independently of one another, are a C.sub.1 to C.sub.20 alkyl, cycloalkyl or alkylaryl group or are a group of the formula [AO].sub.nR.sup.a, where A is C.sub.2 to C.sub.4 alkylene, R.sup.a is H, a C.sub.1 to C.sub.20 alkyl, cyclohexyl or alkylaryl group, and n is 2-250, R.sup.16, independently of any other, is NH.sub.2, NR.sup.bR.sup.c or OR.sup.dNR.sup.eR.sup.f, where R.sup.b and R.sup.c, independently of one another, are a C.sub.1 to C.sub.20 alkyl, cycloalkyl, alkylaryl or aryl group, or are a hydroxyalkyl group or are an acetoxyethyl (CH.sub.3COOCH.sub.2CH.sub.2) or a hydroxyisopropyl (HOCH(CH.sub.3)CH.sub.2) or an acetoxyisopropyl (CH.sub.3COOCH(CH.sub.3)CH.sub.2) group; or R.sup.b and R.sup.c together form a ring of which the nitrogen is a part, in order to construct a morpholine or imidazoline ring; R.sup.d is a C.sub.2-C.sub.4 alkylene group, R.sup.e and R.sup.f each independently of one another are a C.sub.1 to C.sub.20 alkyl, cycloalkyl, alkylaryl or aryl group or a hydroxyalkyl group, and where a, b, c and d are mole fractions of the respective structural subunits S1, S2, S3, and S4, where a/b/c/d=(0.10.9)/(0.10.9)/(00.8)/(00.8), and with the proviso that a+b+c+d is 1.

5. The epoxy resin composition according to claim 1 wherein the second polymer is a melamine sulfonate formaldehyde condensate, a naphthalene sulfonate formaldehyde condensate, or a lignosulfonate.

6. The epoxy resin composition according to claim 1, wherein a weight ratio of the first polymer to the second polymer is between 2 to 1 and 1 to 2.

7. The curable epoxy resin composition according to claim 1, wherein the dispersant is obtained by: a) providing the first polymer, b) providing the second polymer, c) preparing an aqueous solution comprising the first and the second polymer and d) spray-drying the aqueous solution to obtain the dispersant.

8. The epoxy resin composition according to claim 1, additionally comprising at least one curing agent and/or at least one reactive diluent.

9. The epoxy resin composition according to claim 1, wherein the composition is present as a multi-component system.

10. A cured epoxy resin obtainable by curing an epoxy resin composition according to claim 1 or by mixing the components and curing a multi-component system wherein the composition is present.

11. A solid filler comprising a dispersant, wherein the dispersant comprises: a) at least one first polymer, which is a comb polymer having a polymer backbone comprising acid groups and side chains which are linked to the polymer backbone, and b) at least one second polymer, which is a condensate of, at least, an aromatic compound and formaldehyde; or a lignosulfonate

12. A method for producing a curable epoxy resin composition according to claim 1, comprising the steps of adding at least one first polymer, which is a comb polymer having a polymer backbone comprising acid groups and side chains which are linked to the polymer backbone, and at least one second polymer, which is a condensate of, at least, an aromatic compound and formaldehyde or a lignosulfonate, to at least one epoxy resin and/or to at least one inorganic filler.

13. The method according to claim 12, wherein the first polymer and the second polymer is added in the form of a dispersant which is obtainable or obtained by preparing an aqueous solution comprising the first and the second polymer, and spray-drying the aqueous solution to obtain the dispersant.

14. The method according to claim 12, wherein the inorganic filler is coated with the first polymer, the second polymer and/or the dispersant, wherein the inorganic filler is first impregnated and/or wetted with a solvent, and subsequently the first polymer, the second polymer and/or the dispersant is added to and/or intermixed with the inorganic filler.

15. The method comprising applying a dispersant as defined claim 12 (i) as a dispersing agent for inorganic fillers in curable epoxy resin compositions, (ii) for improving compressive strength of curable epoxy resin compositions and/or (iii) for improving the flexural strength of curable epoxy resin compositions.

Description

SHORT DESCRIPTION OF FIGURES

[0268] FIG. 1 shows the effective bearing area of a comparative epoxy composition CV1 (left) and an inventive epoxy composition CE1 (right);

[0269] FIG. 2 shows a view on top of a cured inventive epoxy composition CE1 15 days after preparation.

EXEMPLARY EMBODIMENTS

1. Production of Dispersants

[0270] The dispersants have been produced in line with WO 2013/020862 A1 (Sika Technology AG) which is incorporated herein by reference.

1.1 Production of a First Solid Dispersant D1

[0271] 500 kg Sikament R-550C (trademark of Sika, CH), a polycarboxylate of comb class with a polyacrylic backbone and a PEG side chain combined by an ester, Mw about 21500, 40% s.c., pH 5.5-6.5, was mixed with 500 kg Sikament FF-86 (trademark of Sika, CH), a sulfonated melamine formaldehyde (SMF) resin at 40% s.c., pH 10-13, at room temperature (25 C.) in a conventional reactor of 1.5 m.sup.3 capacity with a paddle stirrer for 20 minutes until a homogenous mixture has been obtained. This mixture was slightly heated to 60 C. to decrease viscosity and energy costs during spray drying. Spray drying was performed at 200 C. inlet temperature and 120-150 C. in outlet (using air heated). The resulting product passed through a sieve to separate eventually formed waxy or syrupy parts (<1% w/w). The final spray-dried product can be stored within 25 kg coated bags for about 1 year.

1.2 Production of a Second Solid Dispersant D2

[0272] 200 kg Viscocrete PC-2 (trademark of Sika, CH), a polycarboxylate and comb polymer with a polymethacrylic backbone and a PEG side chain attached by an ether bond, 50% s.c., pH 3.5-5.5, was mixed with 800 kg Sikament FF-86, a sulfonated melamine formaldehyde (SMF) resin at 40% s.c., pH 10-13, at room temperature (25 C.) in a conventional reactor of 1.5 m.sup.3 capacity with a paddle stirrer for 20 minutes until a homogenous mixture has been obtained. This mixture was slightly heated to 60 C. to decrease viscosity and energy costs during spray drying. Spray drying was performed at 200 C. inlet temperature and 120-150 C. in outlet (using air heated). The final spray-dried product can be stored within 25 kg coated bags for about 1 year.

2. Production of Epoxy Resin Composition

2.1 Inventive Three-Component Epoxy Resin Composition E1

[0273] A three-component system was produced as the basis for an epoxy grout with the following components K1, K2 and K3:

[0274] Binder Component K1 with Epoxy Resin:

TABLE-US-00001 Component wt. % Bisphenol A-epichlorohydrin resins with average 74.7 molecular weight >700 Mixture of silicone-free defoamer, solvent naphtha 0.3 and 2-methoxy-1-methylethylacetate 1,6-Hexanediol diglycidyl ether 25 Total 100

[0275] The epoxy resin was charged first. All other materials were added and homogenized for about 5 minutes.

[0276] Curing Component K2 with Curing Agent:

TABLE-US-00002 Component wt. % Triethylenetetramine 100

[0277] Further Component K3 with Filler:

TABLE-US-00003 Component wt. % Quartz sand mixture 79.5 TiO.sub.2 white pigment 0.45 Cement, particle size <0.06 mm 20 Iron oxide black 0.05 Solution of dispersant D1 (20 wt. % dispersant 1 D1 dissolved in 80 wt. % benzyl alcohol) Total 101

[0278] Component K3 is composed of a mixture of different quartz sands with particle sizes in the range of 0.06 mm to 3.2 mm. The particle size distribution of the quartz sand mixture is shown in FIG. 1. In addition, component K3 contains cement as inorganic finely divided filler and a low proportion of titanium dioxide and iron oxide as pigments.

[0279] The fillers were successively weighed and placed in a stirred tank (the coarse fillers first, the finely divided fillers last). Then, the benzyl alcohol was added and mixed for about 5 minutes at RT. Subsequently, dispersant D1 in powder form was added and mixed for another 5 minutes at RT. A Hobart planetary mixer N50 CE at level 1 was used as the stirring unit.

2.2 Comparative Three-Component Epoxy Resin Composition V1

[0280] For reasons of comparison, a further three-component epoxy resin composition V1 has been produced similar to the inventive three-component epoxy resin composition E1. However, instead of 1 wt. % of a solution of dispersant D1, a solution of 20 wt. % Sikament R-550C (trademark of Sika, CH) dissolved in 80 wt. % benzyl alcohol has been used in component K3.

3. Production of Curable Epoxy Resin Compositions CE1 and CV1

[0281] A curable epoxy composition CE1 according to the invention was prepared by mixing components K1, K2 and K3 of the three-component epoxy composition E1. The mixing ratio of component K1:K2:K3 was 6:1:35 parts by weight. The density of the prepared epoxy composition CE1 was 2.346 g/cm.sup.3.

[0282] Similarly, a comparative curable epoxy composition CV1 was prepared by mixing components of the comparative three-component epoxy composition V1. Also with the comparative curable epoxy composition CV1 the mixing ratio of component K1:K2:K3 was 6:1:35 parts by weight. The density of the prepared epoxy composition CV1 was 2.299 g/cm.sup.3.

4. Properties of Epoxy Resin Compositions

4.1 Flow Behavior

[0283] The flowability of epoxy compositions CE1 and CV1 was determined using a brass cone (about 500 g epoxy resin mortar) in accordance with DIN EN 13395-1 or EN 1015-3 and the flow spread (diameter) was determined 5 minutes after mixing. For comparative curable epoxy composition CV1 the flow spread was 204 mm. The flow spread for the curable epoxy composition CE1 according to the invention was 210 mm, which is an improvement of about 3%.

4.2 Compressive Strength

[0284] The compressive strengths of epoxy compositions CE1 and CV1 was determined in line with standard ASTM-0579-01 (2012) with cubic test specimens of 50 mm50 mm50 mm at 23 C. The following table gives an overview of the results:

TABLE-US-00004 Compressive strength [N/mm.sup.2] Curing time Composition CV1 Composition CE1 1 23.7 29.1 3 55.2 54.5 7 73.2 73.5 28 86 86

[0285] Remarkably, the early compressive strength after 1 day is clearly higher (+23%) for inventive composition CE1 when compared with comparative composition CV1.

4.3 Flexural Strength

[0286] The flexural strengths of epoxy compositions CE1 and CV1 was determined in line with standard ASTM-0580-02 (2012) at 23 C. The following table gives an overview of the results:

TABLE-US-00005 Flexural strength [N/mm.sup.2] Curing time Composition CV1 Composition CE1 1 13.9 15.37 3 21.4 22.9 7 23.7 24.7 28 26.2 28.0

[0287] At all times (1 to 28 day), the flexural strength inventive composition CE1 is significantly higher when compared with comparative composition CV1.

4.4 Further Properties

[0288] Additionally, the effective bearing area according to ASTM C-1339 has been determined for both compositions CE1 and CV1. For both systems the effective bearing area was found to be 97% (see FIG. 1) and no segregation could be observed.

[0289] Optical inspection of the inventive epoxy composition CE1 15 days after mixing did not reveal any cracks or fissures (see FIG. 2).

[0290] Thus, these results clearly show that inventive dispersants can be used in order to improve flowability, early strength, and flexural strength of curable epoxy resin composition with high filler contents without affecting surface quality and effective bearing area.

[0291] It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted.