AQUEOUS ALKYD DISPERSIONS WITH IMPROVED APPLICATION PERFORMANCES IN TERMS OF RESISTANCE TO BLOCKING AND YELLOWING, HARDNESS DEVELOPMENT AND SHINE

Abstract

The present invention relates to aqueous alkyd resin dispersions comprising a) a short oil alkyd resin comprising, in its fatty acid component a1), at least one polyunsaturated fatty monoacid a11) having at least two unsaturations per molecule and comprising at least 35% by weight of a monoacid a111) having conjugated unsaturations, the content by weight of said fatty monoacid a111), with respect to said alkyd resin, being at least 5%, preferably from 5% to 40% and more preferably from 5% to 35%, and b) at least one anionic phosphate surfactant. The invention also covers a preparation process and its use in decorative coatings. The coatings based on these aqueous dispersions exhibit improved performance qualities in resistance to blocking and yellowing, in development of hardness and in gloss.

Claims

1) An aqueous alkyd resin dispersion comprising: a) a short oil alkyd resin having a Noury viscosity at 110° C. according to AFNOR XPT 51213 ranging from 7000 to 13 000 mPa.Math.s and comprising, in its fatty acid component a1), at least one polyunsaturated fatty monoacid a11) having at least two unsaturations per molecule and a content by weight of monoacid a111) having conjugated unsaturations of at least 35%, the content by weight of said fatty monoacid a111), with respect to said alkyd resin, being at least 6%, preferably from 5% to 40%, b) at least one anionic phosphate surfactant which is a phosphate alkyl alkoxy ester.

2) The aqueous dispersion of claim 1, wherein said fatty monoacid a11) is a product of the dehydration of castor oil.

3) The aqueous dispersion of claim 1 wherein the acid number of said resin is less than 25 KOH/g.

4) The aqueous dispersion of claim 1 wherein said surfactant b) is a phosphate ester of a C.sub.10 to C.sub.16 alcohol which is alkoxylated with from 4 to 10 ethoxy units.

5) The aqueous dispersion of claim 4 wherein said surfactant b) comprises a phosphate diester and a phosphate monoester of said alcohol.

6) The aqueous dispersion as claimed in claim 1 wherein said surfactant b) is a mixture of phosphate monoester and of phosphate diester with the ratio by weight of the phosphate monoester to the phosphate diester being from 0.8 to 1.2.

7) The aqueous dispersion as claimed in claim 4 wherein said alcohol is a C.sub.12 to C.sub.14 alcohol.

8) The dispersion of claim 7 wherein the number of said alkoxy units is from 4 to 8.

9) The dispersion of claim 1 wherein the content by weight of said surfactant b) with respect to said dispersion varies from 1% to 3%.

10) The dispersion of claim 1 wherein the content by weight of said alkyd resin a) with respect to said dispersion varies from 35% to 65%.

11) The dispersion of claim 1 wherein said dispersion comprises, in addition to said surfactant b), a surfactant c) chosen from the group consisting of polymeric non-ionic surfactant with a ratio by weight of anionic surfactant b) to non-ionic surfactant c), b)/c), ranging from 1 to 3.

12) The dispersion of claim 1 wherein said resin comprises, in its acid component A, at least one aromatic dicarboxylic acid or anhydride a2) and optionally an aromatic monocarboxylic acid a3) and, in its alcohol component B, a polyol b1) with a functionality ranging from 3 to 6.

13) The dispersion as claimed in claim 1 wherein said alkyd resin additionally comprises, in its fatty acid component a1), at least one other non-conjugated polyunsaturated fatty monoacid a12) having at least two unsaturations per molecule and comprising at least 90% by weight of a non-conjugated polyunsaturated monoacid a121).

14) A process for the preparation of an aqueous dispersion of claim 1, said process comprising the following successive stages: i) Preparation of said alkyd resin a) in bulk, ii) Melting said resin a), iii) Addition of said surfactant b) and optionally of a non-ionic surfactant c), iv) Partial addition of water, before v) Neutralization of the acidity of a) and of b) by a base, said base preferably being selected from LiOH, KOH, NaOH, NH.sub.4OH and tertiary amines, vi) Emulsification by phase inversion with adjustment of the solids content after the emulsification.

15) The process of claim 14 wherein stages ii) and iii) are carried out at a temperature ranging from 80 to 100° C., stage iv) at a temperature ranging from 80 to 65° C., stage v) at a temperature ranging from 60 to 70° C. and stage vi) at a temperature ranging from 55 to 65° C.

16) A coating composition comprising an aqueous dispersion of claim 1.

17) The composition of claim 16 which is an aqueous paint, varnish or stain composition.

18) (canceled)

19) (canceled)

20) (canceled)

Description

EXPERIMENTAL PART

1) Starting Materials (See Table 1 Below)

[0056]

TABLE-US-00001 TABLE 1 Technical Character- Name Chemical name function istics SOFA Soybean fatty acid a12 Function- Nouracid ® (90% non-conjugated ality 1 SZ 35 polyunsaturated a121)) Nouracid ® DE Dehydrated castor a11 Function- 656 fatty acid (62% of ality 1 polyunsaturated a111)) Benzoic acid Benzoic acid a3 Function- ality 1 Pentaerythritol Pentaerythritol b1 Function- ality 4 Phthalic anhydride Phthalic anhydride a2 Function- ality 2 10% LiOH Lithium hydroxide as Neutralizing a 10% by weight agent solution (base) Alkoxylated alkyl Ionic phosphate (C.sub.13 surfactant b) alkyl, 6 EO), mono/diester = 0.8-1.2, surfactant Ethoxylated/ Non-ionic propoxylated surfactant c) C.sub.4-C.sub.8 alcohol EO/PO ratio of 1

2) Examples

[0057] 2.1) Synthesis of the alkyd A for the dispersion B according to the invention

Example 1

[0058] 285 g of soybean fatty acid (SOFA) and 95 g of Nouracid® DE656, 265.9 g of pentaerythritol, 287.1 g of phthalic anhydride and 166.3 g of benzoic acid are charged to a 1.5 liter reactor comprising: [0059] a dip pipe for the addition of nitrogen, [0060] a temperature probe, [0061] a reflux condenser supplied with water at 12° C., [0062] a round-bottomed flask for recovering the water resulting from the esterification reaction.

[0063] While bubbling nitrogen through it, the combined mixture is brought to 240° C. using an electric heating mantle and the water formed is distilled as it is formed until an acid number of less than 12 is obtained. At the end of the synthesis, a viscous alkyd resin A is obtained which exhibits the following characteristics: [0064] Acid number: 11.5 mg KOH/g [0065] Solids content: 100% [0066] Noury viscosity at 110° C. according to the AFNOR XPT 51213 method: 110 000 mPa.Math.s
2.2) Dispersion of the alkyd A in order to obtain the dispersion B according to the invention

Example 2

[0067] 477.1 g of alkyd resin A obtained according to the operating conditions of example 1 described above, premelted at 80-100° C., are introduced into a 1 liter reactor. When the temperature of the reactor is stabilized at 85° C., the following two surfactants are introduced: the phosphate surfactant (19.7 g) and the non-ionic surfactant, which is the ethoxylated/propoxylated C.sub.4-C.sub.8 alcohol (9.7 g).

[0068] The mixture is left stirring for 30 minutes. 112 g of water are subsequently introduced over 30 minutes and the reactor is cooled down to 65° C. 55.3 g of 10% LIOH are then introduced over 30 minutes in order to neutralize the alkyd and the phosphate surfactant. The mixture is left stirring for 30 minutes while cooling down to 60° C. Finally, 345 g of water are introduced over 2 hours while maintaining the temperature at 60° C. The reactor is subsequently cooled to ambient temperature and the solids content adjusted to 50%.

[0069] In the end, an emulsion B is obtained which exhibits the following characteristics: [0070] Solids content: 50% [0071] pH: 7.5 [0072] Brookfield viscosity at 23° C.: <100 mPa.Math.s [0073] Size of the particles: <200 nm

[0074] The stability on storage at 50° C. for 1 month relating to the variation or not in the solids content of the emulsion B, according to the invention, in comparison with a reference commercial product which is Synaqua®4804 from Arkema, is presented in table 2 below.

[0075] The stability on storage at 50° C. consists in measuring the solids content at the surface of the sample and in comparing it with the solids content measured at the bottom of the sample. If, after one month of storage at 50° C., the difference in solids content measured is not greater than 2%, the stability is regarded as good.

TABLE-US-00002 TABLE 2 Emulsion Stability 50° C. Emulsion B according to the Good invention Commercial alkyd emulsion Good Synaqua ® 4804 (Arkema)

[0076] The yellowing of the alkyd emulsion B according to the invention is also compared with that of Synaqua®4804. The results obtained are collated in table 3 below.

TABLE-US-00003 TABLE 3 Yellowing index according to ASTM 313-96 1 month at ambient 1 month at Emulsion T° C. 50° C. Alkyd emulsion B 8 18.7 invention Synaqua ® 4804 8.8 21.4 (comparative)

[0077] The alkyd emulsions compared were formulated in a gloss paint with a pigment volume concentration (PVC) of 18% and with a TiO.sub.2 content of 24% with an iron-based drying agent.

Formulation Used (See Table 4 Below)

[0078]

TABLE-US-00004 TABLE 4 Component/Reference Function Parts by weight Water 141.6 Acticide ® MBS Biocide 2 Disperbyk ® 190 Dispersing agent 6 Byk ® 022 Antifoam 1.5 Tiona ® 595 Titanium dioxide 240 Alkyd dispersion Binder 562.7 (at 50% solids content) Borchi Oxy-Coat ® 1101 Iron-based drier 1.4 Coapur ® 830W Thickener 5.6 Coapur ® 2025 Thickener 39.2
Calculated Characteristics of the Formulation No. 1 (without Drier): [0079] PVC=18.2% [0080] Solids content by weight=approximately 54% [0081] Solids content by volume=approximately 41%

[0082] The performance qualities relating to the resistance to yellowing, the development of hardness, the resistance to blocking and the gloss of the formulation of the dispersion, according to the invention, were compared with those of the formulation with Synaqua® 4804 in table 5 below.

TABLE-US-00005 TABLE 5 Yellowing index according 20/60° to ASTM 313-96 Resistance to blocking Gloss 1 month Development of 48 h of drying, 48 h of drying, 24 h at at ambient 1 month hardness (s) 24 h of contact 1 h of contact, ambient Formulation T ° C. at 50° C. 1 day 4 days ambient T ° C. 50° C. T ° C. Paint with alkyd 1.7 8.3 63 106 1 1 94/97 emulsion B Paint with 2.8 9 59 96 7 8 90/95 Synaqua ® 4804

Tests and Methods Used

[0083] These tests and methods are valid in general for the characteristics mentioned in the description and in particular in the examples presented.

1) Solids Content:

[0084] Evaluation according to ISO 3251 according to the conditions: 1 g of dispersion for 1 hour at 125° C. and the result is expressed in %.

2) Viscosity:

[0085] Evaluation of the Noury viscosity at 110° C. on bulk resin according to the standard AFNOR XPT 51213 and expressed in mPa.Math.s.

[0086] Evaluation of the Brookfield viscosity at 23° C., 10 rpm, using the 2 and 3 spindles on a Brookfield RVDVE-230 viscometer according to the standard ISO 2555.

3) Size of the Particles:

[0087] The size of the particles is measured using a device of Zetasizer-Malverb Instruments Ltd type. The dispersion sample is diluted in a transparent cell using filtered deionized water, the size of the particles being measured by 90° laser scattering.

4) Acid Number and Hydroxyl Number:

[0088] The acid number is evaluated according to the standard ISO 3682.

[0089] The hydroxyl number is evaluated according to the standard NFT 30-403.

5) Hardness:

[0090] The hardness is evaluated using a Persoz hardness pendulum on films with a wet thickness of 100 μm applied to glass sheets after different drying times and according to the standard ISO 1522.

6) Yellowing

[0091] Device of the “Dr Lange” Micro Color LMC spectrocolorimeter type.

[0092] Measurements of the yellowing index Yi according to the standard ASTM 313-96 on dry films at different drying times.

[0093] The films with a wet thickness of 150 μm are applied to Leneta charts using a Bird film applicator.

7) Gloss:

[0094] The measurements are taken using a BYK Gardner GmbH micro-TRI-gloss glossmeter at 20°, after different drying times for wet films with a thickness of 200 μm deposited on glass sheets and according to the standard ISO 2813.

8) Resistance to Blocking:

[0095] The paints to be evaluated are applied to two Leneta 2A charts at a chosen thickness using a film applicator. These paints are stored in a climate-controlled chamber (at 23° C.±1° C. and at 50%±5% RH) for a predetermined time. The painted faces of these charts are subsequently placed face to face between 2 glass sheets. The assembly is compressed by a weight which makes it possible to obtain a pressure of 50 g/cm.sup.2 over the entire test surface. The painted faces are left in contact in a climate-controlled chamber for a predetermined time. At the end of the contact time, the charts are gently separated by pulling on the 2 charts, in all directions.

[0096] The damage caused on the paint films is then quantified on a scale varying from 0 to 8 according to the instructions given in the table below (with 0 signifying the best performance and 8 signifying the worst performance):

TABLE-US-00006 Scale of evaluation of the resistance to blocking 0 No adhesion between the films and no noise during the separation of the charts 1 Detachment of the films with a slight noise but without a detrimental change in the test surface 2 Tearing < 10 points on the test surface 3 Tearing < 50 points on the test surface 4 Tearing > 50 points on the test surface 5 Tearing of the surface < 20% of the test surface 6 Tearing of the surface between 20% and 50% of the test surface 7 Tearing of the surface > 50% of the test surface 8 Complete tearing of the test surface