WO2011042652A1

WO2011042652A1 - Use of glycerol acetals as coalescing agents for lacquers, paints or varnishes and compositions thereof

Info

Publication number: WO2011042652A1
Application number: PCT/FR2010/052093
Authority: WO
Inventors: Jean-Luc Couturier; Jean-Pierre Lallier; Jean-Luc Dubois
Original assignee: Arkema France
Priority date: 2009-10-06
Filing date: 2010-10-05
Publication date: 2011-04-14
Also published as: FR2950894B1; FR2950894A1

Abstract

The present invention relates to the use, as a solvent and/or coalescing agent for aqueous lacquer, aqueous paint or aqueous varnish, of a compound having the following formula (I) or (II): where R₁ is -H or -CH₃ and R₂ is -C₆H₁₃. The invention also relates to paint, lacquer or varnish formulations including compounds having formula (I) or (II) above.

Description

USE OF GLYCEROL ACETALS AS COALESCENCE AGENTS FOR LACQUERS, PAINTS OR VARNISHES AND THEIR COMPOSITIONS

The present invention relates to the field of paints, lacquers and varnishes, and more particularly relates to the use of glycerol acetals as solvents, and more specifically as coalescing agents in paints, lacquers, varnishes and pigment concentrates.

The quality and the rendering of a decorative painting depends largely on the quality of the different raw materials used in its composition.

One of the desired qualities of a painting is that it forms a uniform coating. In order to obtain a suitable film formation, a coalescing agent is incorporated into the aqueous dispersion formulations. A coalescing agents most used currently is the mono-isobutyrate of 2,2,4-trimethyl-1, 3-pentanediol, available under the trade name Texanol ^® from Eastman Chemical Company.

However, the European directive 2004/42 / EC for paints and varnishes building and paints automotive repair indicates that for the application "thin layer", the solvents used must not be volatile organic compounds or VOC, that is to say, according to this directive, must not have a boiling point below 250 ° C.

Thus, the 2,2,4-trimethyl-1,3-pentanediol mono-isobutyrate, which has a boiling point of 247 ° C., can no longer be used as a coalescing agent in aqueous dispersion paint formulations in view of this directive.

Patent Application EP2050784 describes the use of glycerol acetals as coalescing agents. Nevertheless, these products are not entirely satisfactory, so that we are always looking for an alternative to them.

The aqueous dispersion paint formulations comprise water, various adjuvants such as dispersant, neutralizer, pigment, bactericide, etc., a latex which consists of fine particles of 0.05 to 5 μηη of diameter dispersed in an aqueous phase and a coalescing agent.

Obtaining a film from an aqueous dispersion paint formulation generally takes place in three steps. The first is the concentration of the latex by evaporation of the water or by absorption of the latter by a porous support. This elimination of water has the main effect the formation of a thin film of interstitial water between the latex particles very close to each other. There is the appearance of capillary forces that will force the particles to continue their approximation.

At this point, the second step which is the filming can begin: the latex particles come into contact with each other, undergoing deformations. The spherical particles then gradually take the hexagonal form.

The last step is called coalescence. The macromolecular chains of the different latex particles diffuse from one particle to another: this is interdiffusion. This results in the loss of the hydrophilic membranous framework existing between the juxtaposed particles. It is during this last very slow stage that the film acquires its optimal properties, in particular its mechanical properties and resistance to liquids (solvents, water).

This film formation depends essentially on the glass transition temperature (Tg) of the polymer. Thus, a given latex will give rise to good filming only if the temperature is higher than the minimum film formation temperature (MFFT) characteristic of a latex.

The role of a coalescing agent is therefore to lower the TMF of the treated latex to facilitate filming at low temperatures.

There is therefore a continuing need for new coalescing agents with high performance, and not included in the list of volatile organic compounds according to European Directive 2004/42 / EC for paints and varnishes, building and automotive paints.

The inventors have shown that specific glycerol acetals make it possible to imitably lower the TMF of a latex. The invention therefore relates to the use as a solvent and / or coalescence agent for aqueous lacquer, aqueous paint or aqueous varnish, of a compound of formula (I) or (II) below:

(I) (i)

wherein R 1 is -H or -CH ₃ and R ₂ is -C ₆ H 13.

The invention also relates to the use of mixtures of compounds of formula (I) and (II) as a solvent and / or coalescing agent for aqueous lacquer, aqueous paint or aqueous varnish.

The compounds of formula (I) and (II) above have many advantages, such as easy synthesis leading to excellent yields, a strong lowering of the MFFT, and a decrease in the viscosity of the compositions in which they are added. These compounds are also non-VOC and can be completely bioresourced.

As a preamble, it will be noted that the expression "included between" must be interpreted, in the present description, as including the boundaries cited.

The coalescing agents defined above are 2-hexyl-1,3-dioxolane-4-methanol, 2-hexyl-1,3-dioxan-5-ol, 2-hexyl-2-methyl-1, 3- dioxolane-4-methanol and 2-hexyl-2-methyl-1,3-dioxan-5-ol.

Preferably, the glycerol acetals of formula (I) and (II) are prepared according to a process comprising the following steps:

(a) mixing glycerol with 2-octanone or heptanal in the presence of an acid catalyst

(b) recovering the compound of formula (I) and or (II) obtained.

The molar ratio of glycerol with respect to 2-octanone or heptanal is generally between 0.5 and 1. According to the above method, excellent yields are obtained, greater than 90%, and even greater than 95%. Such yields are generally obtained with reaction times of about 1 to 6 hours. The process can be conducted without solvent or in the presence of a solvent such as toluene, xylene or cyclohexane allowing azeotropic removal of the water formed.

The compound according to the invention of formula (I) or (II) is preferably used as a coalescing agent in pure form, that is to say without solvent.

The reaction is generally carried out hot at a temperature of between 80 ° C and 150 ° C. In a preferred embodiment, water formed during the reaction between glycerol and heptanal or 2-octanone is removed using Dean-Stark apparatus.

The reaction is generally carried out under an inert atmosphere, for example under nitrogen.

The glycerol used is preferably bioresourced glycerol, comprising contemporary carbon. It can be pure or be in the form of a composition comprising up to 20% by weight of water relative to the total weight of the composition. Such compositions are in particular derived from the synthesis of biodiesel.

The acid catalyst used is preferably phosphoric acid or an acid catalyst immobilized on a resin. As an example of a catalyst, mention may be made of Amberlyst® 15 sold by Rohm & Haas. The acid catalyst is used in an amount of between 0.5 and 10% by weight relative to the total weight of glycerol.

Preferably, the 2-octanone and / or heptanal used are preferably bioressourc compounds, comprising contemporary carbon.

By way of example, bioressoured heptanal comprising contemporary carbon may be derived from the high temperature cracking of castor oil, or its derivatives such as ricinoleic acid or methyl ricinoleate, this oil or these derivatives being themselves from seed of castor seedlings. By way of example, the bioressourced 2-octanone comprising contemporary carbon may be derived from the basic high-temperature cracking of castor oil or its derivatives such as ricinoleic acid or methyl ricinoleate, this oil or these derivatives being themselves derived from seeds of castor seedlings.

Thus, in a preferred embodiment of the invention, all the reagents used for the synthesis of the products of formula (I) and / or (II) are bioressourcés, so that the products of formula (I) and / or (II) II) are obtained from renewable raw materials, and are therefore bioressourced themselves

The compounds of formula (I) and / or (II) are used as coalescing agents, generally in amounts of between 0.1% and 10% by weight, preferably between 0.5% and 5% by weight, and most preferably between 1% and 2% by weight relative to the total weight of the final composition.

The invention also relates to an aqueous paint, an aqueous lacquer, an aqueous lacquer, comprising:

at least one pigment or dye;

a resin,

- a charge, and

a compound of formula (I) and / or (II).

Preferably, said lacquers, paints and varnishes further comprise a compound selected from a neutralizing agent, a dispersing agent, a thickening agent, a drying retarder, an anti-foaming agent, a biocidal agent, and their mixtures.

The paint compositions, lacquer or varnish defined above, can thus include:

• 1 to 30 parts by weight of at least one pigment or dye such as titanium dioxide, and in particular the ΤΊΟ2 RHD2 ^® sold by the company Tioxide,

• 5 to 60 parts by weight of at least one resin, for example a styrene-acrylic emulsion, and in particular the product Craymul 2421 ^® sold by the company Cray Valley, From 1 to 60 parts by weight of at least one filler, for example calcium carbonate and in particular the product MIKHART 2 ^® , marketed by the company PROVENÇALE,

From 0.1 to 10 parts by weight of at least one coalescing agent of formula (I) or (II) as defined above,

From 0 to 3 parts by weight of a neutralization agent, for example ammonia,

• 0 to 2 parts by weight of at least one dispersing agent, for example an acrylic polymer and in particular the product Coatex P90 ^® sold by the company Coatex,

• 0 to 10 parts by weight of at least one thickener, for example a cellulose ether and in particular the product Natrosol ^® 330 sold by the company Hercules Aqualon PU or a polymer and in particular the product COAPUR 3025 ^® sold by the company Coatex ,

From 0 to 10 parts by weight of a drying retarder, for example polyethylene glycol 200 marketed by the company CAMEO Chemicals;

• 0 to 5 parts by weight of customary auxiliaries and additives, for example an anti-foam and in particular the product TEGO 1488 ^® sold by the company Tego Chimie and a biocide, and in particular the product ACTICIDE MBS ^® marketed by THOR society

From 0 to 50 parts by weight of added water,

0 to 30 parts by weight of organic solvent, for example hexylene glycol.

Preferably, the paint defined above is a glossy, matte or satin paint. Example 1 Synthesis of glycerol-heptanal acetals

In a 500ml glass reactor equipped with a mechanical stirrer, a Dean-Stark surmounted by a refrigerant and a temperature probe, one charge 46.0 g of glycerol (0.5 mol), 62.8 g of heptanal (0.55 mol), 2 g of Amberlyst 15 resin and 100 g of toluene. The reaction mixture is refluxed for 3 hours and the water formed (8.7 g) is removed in Dean-Stark. After reaction, the reaction mixture is cooled, filtered, and the excess of heptanal is evaporated under vacuum with Rotavap ^® .

91.3 g of expected product (glycerol acetal / heptanal) are obtained in the form of a slightly yellow liquid (yield = 97%).

The product obtained is a mixture of:

60 parts by weight of acetal in the 5-ring, 2-hexyl-1,3-dioxolane-4-methanol (compound 1 according to the ivention), and 40 parts by weight of acetal in the ring at 6 2-hexyl-1,3-dioxan-5-ol. (Compound 2 according to the invention). Example 2 Synthesis of acetals qlycerol-2-octanone

In a 500 ml glass reactor equipped with a mechanical stirrer, a Dean-Stark surmounted by a condenser and a temperature probe, 46.0 g of glycerol (0.5 mol), 70.5 g 2-octanone (0.55 mol), 2 g of Amberlyst 15 resin and 100 g of toluene. The reaction mixture is refluxed for 3 hours and the water formed (8.6 g) is removed in Dean-Stark. After reaction, the reaction mixture was cooled, filtered, and the excess of 2-octanone was evaporated in vacuo to Rotavap ^®.

96.1 g of expected product (acetal glycerol / 2-octanone) are obtained in the form of a slightly yellow liquid (yield = 95%).

The product obtained is the acetal in a 5: 2-hexyl-2-methyl-1,3-dioxolane-4-methanol ring. (Compound 3 according to the invention)

Example 3: Measurement of the MFFT

Measuring method The MFFT is particularly important to determine for outdoor and cold season applications.

The MFFT is determined using a nickel-plated brass plate producing a gradual temperature gradient. For this, we apply an emulsion film of 75 μιτι on the plate and we observe at what temperature the film is formed.

After closing the lid, the results are recorded after at least 1 hour when the film has begun to form. The method used is in accordance with ASTM D2354. The apparatus used is a MFFT Bac 60 ^® test bench marketed by RHOPOINT Instruments.

The tests were carried out at a temperature of 22 ° C. and at 50% relative humidity.

Results

A Crayrul 2421® styrene-acrylic emulsion sold by Cray Valley having a MFFT of 18 ° C was used, and the lowering of the MFFT depending on the nature and percentage of acetal to this added emulsion was measured.

The following acetals were used:

Compound 1 (Invention): 2-hexyl-1,3-dioxolane-4-methanol

Compound 2 (Invention): 2-hexyl-1,3-dioxan-5-ol

Compound 3 (Invention): 2-hexyl-2-methyl-1,3-dioxolane-4-methanol

Compound 4 (comparative): Iso-butyraldehyde

Compound 5 (Comparative): 2,2,4-trimethyl-1,3 pentanediol monoisobutyrate (Texanol)

Texanol (2,2,4-trimethyl-1, 3-pentanediol monoisobutyrate) being a coalescence agent conventionally used in aqueous paints, the performance of glycerol acetals according to the invention were in particular compared with those of Texanol ^®.

The results are summarized in Table 1 below.

Table 1 0% 1% 2%

Compounds 1 + 2 in 18 ° C 5.3 ° C 2.2 ° C mixture 60/40

Compound 3 18 ° C 13.5 ° C 4 ° C

Compound 4 18 ° C 15.5 ° C 12 ° C

Compound 5 18 ° C 14.5 ° C 9.1 ° C

It is observed that the glycerol acetals according to the invention (Compounds 1, 2 and 3) lead to better performance in terms of lowering the temperature, than those obtained with compounds 4 and 5.

Example 4 Measurement of the viscosity

Coalescing agents usually have the disadvantage of greatly increasing the viscosities of the aqueous paint formulations. On the contrary, the glycerol acetals according to the invention make it possible to lower the viscosity of the compositions in which they are added, as is apparent from Table 2 below.

The following acetals were used:

Compound 1 (Invention): 2-hexyl-1,3-dioxolane-4-methanol

Compound 2 (Invention): 2-hexyl-1,3-dioxan-5-ol

Compound 3 (Invention): 2-hexyl-2-methyl-1,3-dioxolane-4-methanol

Compound 4 (comparative): Iso-butyraldehyde

Measurement method:

Viscosities were measured at room temperature (22 ° C) using a Brookfield DVII viscometer at two different speeds of 10 rpm and 100 rpm. The speed of 10 rpm is representative of the shears obtained during the application of a paint. In the following Table 2, the Brookfield viscosities at: 10 rpm / 100 rpm are given in centipoise.

Results

A Crayrul 2421® styrene-acrylic emulsion sold by Cray Valley having a MFFT of 18 ° C was used, and the viscosity depending on the nature and percentage of acetal added to this emulsion was measured.

Table 2

It is observed that at the usual 2% level for a coalescing agent, and even at 4%, the glycerol acetals according to the invention (coatings 1, 2 and 3) tend to maintain a constant or slightly lower viscosity, what is sought with respect to a very significant increase in the viscosity obtained with Texanol ^® , or conversely a very important decrease observed with compound 4.

Claims

1. Use as a solvent and / or coalescence agent for aqueous lacquer, aqueous paint or aqueous lacquer, of a compound of formula (I) or (II) below:

(I) (i)

wherein R 1 is -H or -CH ₃ and R ₂ is -C ₆ H 13.

2. Use according to claim 1, characterized in that the compound of formula (I) and / or (II) is added in an amount of between 0.1% and 10% by weight, preferably between 0.5% and 5% by weight and most preferably between 1% and 2% by weight relative to the total weight of the final composition.

3. Use according to claim 1 or 2, characterized in that the compound of formula (I) and / or (II) is in pure form, without solvent.

4. Use according to any one of claims 1 to 3, characterized in that the compounds of formula (I) and / or (II) are obtained from renewable raw materials.

5. Aqueous lacquer, aqueous paint or aqueous lacquer comprising:

at least one pigment or dye;

a resin,

- a charge, and

a compound of formula (I) and / or (II) as defined in claims 1 to 3.

6. Lacquer, paint or varnish according to claim 5, characterized in that it further comprises a compound selected from a neutralizing agent, a dispersing agent, a thickening agent, a drying retarder, an anti-aging agent, foam, a biocidal agent, and mixtures thereof.

7. Lacquer, paint or varnish according to claim 5 or 6 comprising:

From 1 to 30 parts by weight of at least one pigment or dye,

From 5 to 60 parts by weight of at least one resin,

From 1 to 60 parts by weight of at least one filler,

From 0 to 3 parts by weight of a neutralization agent,

From 0 to 2 parts by weight of at least one dispersing agent,

From 0 to 10 parts by weight of at least one thickening agent,

From 0 to 10 parts by weight of a drying retarder,

From 0 to 50 parts by weight of added water, and

From 0 to 30 parts by weight of organic solvent.

8. Paint according to claim 7, characterized in that it is a glossy paint, matte or satin.