FR2793801A1 - Protective-insulating coating for various surfaces is applied by treatment of surface to be coated with a dispersion containing hydro-dispersible polycondensate and acrylic, vinyl and-or styrene polymers - Google Patents

Abstract

Aqueous dispersion of hydro-dispersible polycondensate and acrylic, vinyl and/or styrene polymers, and its use for production of protective-insulating coatings are new. The patent refers to use of aqueous dispersion, based on polymer particles containing 0.1-100 (preferably 0.1-40) wt.% of particles of hydro-dispersible polycondensate, and 0-99.9 (preferably 60-99.9) wt.% of particles of acrylic, vinyl and/or styrene polymers, to produce surface coatings on paper, wood, textiles, metal, glass and other materials. The dispersion is preferably made with pigment, and/or fillers, and/or thickener, and/or other additives (especially active pigments or additives), to form film-like or non-film like coating.

Description

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INSULATION COATING AND PROTECTOR FORMULA WITH
A HYDRODISPERSIBLE POLYCONDENSATE.

 The invention relates to the field of surface treatment of various materials, in particular to the surface treatment of wood and steel and more particularly to the insulating and protective coating, preventing the migration of water-soluble compounds present on the surface and in the breast. from the material to the surface of the coating.

 In general, the compositions used for the surface treatment of materials such as metals, paper, glass, wood, building materials may be aqueous or based on organic solvents.

 The use of aqueous formulations, despite their practical and ecological advantages, faces the problem of migration of water-soluble coloring substances present on the surface and in the material to be coated. In contact with an aqueous formulation, these water-soluble substances solubilize and rise to the surface. For example, some species of wood, such as tropical species, are rich in water-soluble dyes called tannins. When these untreated woods are coated with an aqueous system (such as a latex paint) the tannins are extracted from the substrate and migrate to the surface, which they color unsightly. Coloring occurs through successive layers, unless an insulating layer blocks the rise of the coloring substance.

 The same problem of migration arises for the renovation of walls contaminated by a yellowish deposit left by cigarette smoke, by the soot that migrates through the wall of the chimney, by moisture stains resulting from a leak of water. or a lack of waterproofness of the building.

 Similarly, when an aqueous system is applied to untreated steel, rust spots appear almost instantly on the surface.

The phenomenon is called instantaneous corrosion.

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 These coloring substances are generally not soluble in the organic solvents of the glycerophthalic paints; so that the application of a traditional non-aqueous system solves the problem. With a water system, however, all the constituents (binder, pigmentation, additives and solvents) must be selected in order to optimize the insulating power of the coating. These choices are often made at the expense of other properties of use, such as ease of application, open time, appearance, gloss, adhesion, so that the final result gives only a moderate satisfaction by only partially ensuring the objective of blocking the rise of water-soluble substances.

 Some of these coloring substances, water-soluble at basic pH, have an anionic character. One strategy for immobilizing them is to make them insoluble by precipitating them with insoluble cationic resins. No. 3,494,878, filed in 1970, describes the blocking effect of tannins and the instantaneous corrosion obtained by the combination of a film-forming latex and an insoluble cationic or anionic resin. Patent application WO 94/29393 likewise exploits the blocking properties of a non-film-forming cationic resin used in combination with a compatible film-forming aqueous dispersion to formulate an aqueous correction fluid. EP 322 188 (921007) invokes the same principle to improve the water resistance by fixing the anionic surfactants on an aqueous dispersion of a non-film-forming and insoluble polymer functionalized with a weak base. An improvement of the tannin blockage is mentioned as an additional benefit of the combination. It is remarkable that the weakly basic resin loses its blocking efficiency when it is film-forming. In US Pat. No. 3,494,878, it is already observed that certain tannin species escape the blocking power of the cationic resin, which an anionic resin would be more effective to fix.

 A combination of cationic and anionic functionality provides a wider field of blocking efficiency. According to EP 837110, the resin

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 cationic ion exchange (typically a divinylbenzenestyrene copolymer carrying a quaternary ammonium), combined, as in US 3,494,878, with the emulsion polymer, is activated by a water-soluble anionic polymer.

 No. 5,141,784 describes a treatment of a wood rich in tannins which consists in the application of enough carboxylic acid salt and / or a water-soluble polymer functionalized with quaternizable amino groups and with a molecular weight of 50 to 300. US 5,051,283 discloses an aqueous coating which comprises an alkaline salt of a mono- or dicarboxylic acid and a water-soluble polymer bearing quaternizable amino groups and a molecular weight of 50 to 300,000.

 No. 4,075,394 describes the treatment of a wood rich in tannins with a polyaziridine.

 Numerous documents describe the functionalization of addition polymer dispersions based on vinyl or ethylenically unsaturated monomers by amine monomers, optionally quaternized, for coating. EP 290777 and US 4,760,110 claim to obtain amphoteric latex by a two-step process. US 3,404,14 already used a sequential process in 1968 to introduce an aminoacrylate into a functionalized latex. MATBAE is introduced in 2nd stage after neutralization to obtain a stable latex. The latex described in EP 587333 (940316) comprises an insoluble and functionalized tertiary amine polymer grafted onto an acid functionalized water-soluble polymer. The latex is stable and is formulated in semi-transparent stain, water resistant and having a good open time. Blocking of water-soluble substances is not claimed.

 The presence of amine functional groups does not ipso facto confer the effectiveness of blocking tannins and various spots: the formulation plays indeed a determining role: the pH of formulation, the choice of the neutralizing agent, the presence of oxide of zinc, zirconium salts or zinc contribute to the formation of effective complexes:

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According to EP 407085 (1991), anteriorized with US 375,653 (05/07/89), it is possible to obtain a tannin blocking efficiency equivalent to that of a glycerophthalic primer in the solvent phase by formulating a functionalized latex. cationic acid to neutral pH with an aminosilane dispersant.

 EP 622427 (941102) and US 5,527,619 (960618) disclose a combination of an acid functionalized polymer with an aminosilane, which provides excellent tannin blocking and stain properties.

 EP 192077 describes the formulation of a dispersion-based primer comprising a zinc-amine complex of water-soluble polymer.

The primer in question effectively blocks the tannins of the wood. No. 5,681,880 claims an improvement of the previous patent by suggesting replacing the zinc complexes with water-soluble zirconium complexes.

 The applicant has just discovered that the problems mentioned above can be solved more simply by a treatment of the substrate with an aqueous dispersion based on a water-dispersible polycondensate and / or a polymer based on radical-polymerized vinyl or ethylenic monomers.

 It is also possible to formulate a coating with a dispersion according to the invention which has a good insulating power and good application properties and this without the use of specific pigments and specific additives.

 The object of the invention is the use of the aqueous dispersion as described above for the surface treatment of various substrates such as wood, textile, leather, paper, metal, glass and building materials.

 The dispersion according to the invention constitutes both an active binder and a universal binder. Indeed ; it confers by itself a good insulating and protective power without resorting to particular active constituents, although an addition, of these allows to reinforce these effects (binder

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 active). At the same time, the composition lends itself to conventional methods of formulation and makes it possible to obtain low levels of volatile organic compounds. This generates a significant ecological advantage.

 The treatment according to the invention has good properties in application: a good gloss potential, a good tension, a low tack. It will thus satisfy the specifications in both primary wood and metal finishing. Furthermore, the dispersion according to the invention is capable of being modified and formulated at will according to the requirements of the intended application.

 The treatment of the invention is obtained from an aqueous dispersion containing at least one radical polyaddition polymer and a water-dispersible polycondensate.

 The water-dispersible polycondensate is typically a polyester, a polyester-amide, a polyetherester amide or a polyamide whose hydrodispersible character is linked to the incorporation of sulphate or sulphonate groups. Specific compositions of polyesters and polyesteramides, as well as their method of manufacture, are contained in US Pat. No. 5,277,978, WO 95/05413, WO 95/01382 and EP 532961. In addition, water-dispersible polyamides are described precisely in WO 98. / 500450, WO 98/03567.

 The polycondensate may also contain a grafting site such as a reactive double bond by radical polymerization.

 The dispersion of the invention can be obtained in various ways.

In one form, the water-dispersible polycondensate in the form of a powder or an aqueous dispersion is mixed with an aqueous dispersion containing the acrylic, vinyl and / or styrene polymer.

 According to another form, the acrylic, vinyl and / or styrene polymer is obtained by the radical polymerization in aqueous emulsion of at least one acrylic, vinylic and / or styrene monomer in the presence of at least one water-dispersible polycondensate which then plays the role of

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 protective colloid and makes it possible to reduce, or even completely eliminate during synthesis, the micromolecular surfactants harmful to the application.

To achieve the dispersion according to the latter form, the following procedure is carried out:
In a first step, the unsaturated hydrodispersible polycondensate is prepared by polycondensation and functionalization using a chain limiter according to the procedure described later, then an aqueous dispersion is prepared preferably from 0.1 to 40% by weight of the polyamide. and introduced into the bottom of the reactor vessel. The temperature of the medium is brought to the usual temperatures for emulsion polymerizations (typically 50 C to 80 C). The monomer (s) (A) or the mixture (s) of acrylic, vinylic and / or styrenic monomers is then cast at constant speed over the dispersion according to the semi-continuous processes or sequences known from the skilled person. An aqueous solution of water-soluble initiator of the type conventionally used in emulsion is cast in parallel in the reactor so as to initiate the radical polymerization of the monomer or monomers. Possibly a first hydrophilic monomer casting can be carried out before adding, in a second step, the mixture (s) of more hydrophobic monomers to promote a reverse core-shell mechanism and the obtaining of small particles .

A weakly concentrated solution of macromolecular surfactant can also be cast.

The monomer A is chosen from the group containing:
1. Relatively hydrophilic monomers such as C1-C3 alkyl or hydroxyalkyl amides and esters of (meth) acrylic acids and other unsaturated acids, acrylic, methacrylic and itaconic acids, vinyl alcohol esters, acrylonitrile, methacrylonitrile, crotonaldehyde, (meth) acrylates bearing hydrophilic groups such as segments based on polyoxyethylene.

 2. Hydrophobic monomers such as:

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(C 3 -C 12) alkyl (meth) acrylates, styrenics, vinyls, dienes, (meth) acrylates containing a substituted nitrogen atom such as t-butyl aminoethyl methacrylate, diethylethylethyl methacrylate.

 The preferred monomer A is chosen from: acrylic acid methacrylic acid (meth) acrylate substituted with hydroxyalkyls (HEMA, etc.) (meth) acrylates substituted by alkyl Cn, n <3 styrene butyl acrylate ethyl acrylate octyl hexyl (meth) acrylate.

 Preferably, the polycondensates used to carry out the dispersion of the invention are water-dispersible polyamides having at least one unsaturation, hereinafter referred to as PAHDI. They are obtained by polycondensation and functionalization using a chain limiter carrying a radical-polymerizable unsaturated group.

 In general, the polycondensation is carried out between a diacid and a diamine. The hydrodispersibility is obtained by means of a monomer, generally a diacid containing the unit derived from an alkali metal salt of 2 or 1-sulphoisophthalic acid, the salt possibly being a salt of sodium or of potassium , of lithium or of amine corresponding to the following formula:

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Diacids that may be mentioned include: isophthalic, adipic, azelaic, sebacic, dodecandioic, butane-dioic, 1,4-cyclohexyl dicarboxylic, terephthalic (less than 12% weight), dimerized fatty acids (these dimerized fatty acids have preferably a dimer content of at least 98%, preferably they are hydrogenated, they are marketed under the trademark "PRIPOL" by the company "UNICHEMA", the most interesting grades are PRIPOL 1008, PRIPOL 1009 and PRIPOL 1013 or under the brand Empol by Henkel).

 Diamines that may be mentioned include hexamethylenediamine, tetramethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, 1,5-diaminohexane, 2,2,4-trimethyl-1,6diaminohexane, piperazine, 3,3'-dimethyl-4,4'diaminodicyclohexylmethane, 4,4'-diamino-dicyclohexylmethane, 2,2 '- (4,4'diaminodicyclohexyl) propane, isophorone diamine, 1,4-diaminocyclohexane, methylylene diamine. It is also possible to use diamine polyols marketed under the name "Jeffamine" by Huntsman Corp. The preferred grades are Jeffamine D400 and Jeffamine D2000. These polyether chains increase in particular the hydrophilicity of the resins. Their weight can reach up to 60%.

 The diacids and diamines can be replaced by amino acids or lactams such as caprolactam, enanthalactam, laurolactam, their open forms and 1-amino-undecanoic acid.

As chain limiter we can use:
The unsaturated compounds bearing the abovementioned groups may belong to different classes of organic compounds. They

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can be in particular of the R1R2C = CR3X (1) type where the groups or the atoms R1, R2, R3, which are similar or different, are: H, halogen, alkyl, aryl, in particular phenyl, and carboxyl, norbornyl, thienyl, pyrrolyl or furanyl, while the active group X may be: - (CH2) nCOOH with n = 0 to 17; -CH2NH (CH2) 11COOH; - (OCH 2 CH 2) kOH with k = 20 -COO-glycidyl;
Y-C6H4- (CH2) n, - COOR with n; = 0 or 1, Y being -COO, -CONH, where R is H, alkyl or aryl; -CH20H; - (CH2) mNH2 with m = 0 to 18 or- (OCH2CH2) OH.

 Thus, particularly favorable examples of the compounds according to formula (1) are they: acids or esters of unsaturated acids, acrylic, methacrylic, cinnamic, crotonic, citraconic, itaconic, vinylacetic, undecylenic, maleic, fumaric, 5'-norbornene- 2 acrylic, 3'-furanyl-2 acrylic, 3'-pyrrolyl-2 acrylic, N-allyl aminobezoic, N-acryloyl or N-methacryloyl p-aminophenylacetic, N-allyl amino-1 1-undecanoic, and the like.

 Another type of unsaturated compounds, suitable for the process according to the invention, may be possible without being limited to: N-maleimido: hexanoic, p.benzoic and dodecanoic acids and esters, etc. Mention may also be made of anhydrides and imides derived from anhydrides, such as tetrahydrophthalic acid, p. N-maleimido benzoic acid, p- (endo-cis-bicyclo (2,2,1) -5-heptene-2,3-dicarboxylic acid).

 When preparing the dispersions of the invention it is necessary that the number of PAHDI particles in the reactor is large enough that the monomer can be added and polymerized at high speeds. According to the composition and characteristics of the copolyamide used, there is an optimum window in which these conditions are obtained (for a minimum concentration value of 0.1%). We have also observed that the interactions between the monomers and the polyamide vary according to the polarity of the monomers used. So it is necessary

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 optimize the synthesis process (temperature, nature of the initiators) depending on the nature of the polyamide and vinyl monomers or overpolymerized acrylic.

 Compared to conventional dispersions obtained by polymerization and which generally contain from 1 to 3 parts of low mass surfactants which can diffuse out of the paint films, the dispersions obtained by this invention from 0.1 to 10% by weight of polyamide , have the advantage of having small sizes, preferably less than 120 nm and contain only very small amounts of macromolecular surfactants and a majority proportion of high mass surfactant which has the effect of limiting the species as much as possible. likely to migrate into the movies. In addition, the grafting of the polyamide to the acrylic, vinyl and / or styrenic copolymer described in the present invention completely eliminates the migration of this macromolecular surfactant out of the film. This property limits the deterioration of the films over time, eliminating in particular the phenomena of exudation, water sensitivity and loss of adhesion to the substrates.

 The behavior of the dispersion with respect to the mineral fillers usually used can be improved by the presence at the periphery of the latex particles of an ionic and / or polar group bearing polyamide. Grafting when present can stabilize the interactions between mineral fillers and latex particles during the formation of the paint film, thus ensuring better cohesion and resistance to abrasion, especially wet abrasion.

 The dispersion of the invention, whatever its mode of production, consists of: 0.1% to 100% by weight of the total weight of the polycondensate polymer particles, and preferably from 0.1% to 40%, and from -99.9% to 0% by weight of the total weight of the acrylic, vinyl and / or styrenic polymer polymer particles, with a preference ranging from 60% to 99.9%.

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 The size of the particles is between 20 nm and 1 m, preferably less than 120 nm.

 The coating is formulated or not with pigments and fillers, and will therefore be opaque or (semi) -transparent. The additives or active pigments, generally introduced to obtain the blocking of the coloring substances, can also be used in the coating according to the invention in order to reinforce the insulating and protective effect. The coatings obtained after formulation can be film-forming or non-film-forming.

 The coating according to the invention is obtained by the application on the support to be treated and the drying of a composition according to the invention.

 The composition can be formulated or not.

 The drying can be carried out at ambient temperature or at a temperature of 20 ° C., at atmospheric pressure or under reduced pressure.

 According to the monomer composition of the dispersion and its formulation, the coating is suitable for coating inorganic substrates (masonry, walls to be renovated, etc.), organic (wood, paper, leather, etc.) and metal substrates.

 The coating is characterized by the ability to block the rise of water-soluble species, particularly those such as nicotine, wood tannins or metal salts, which cause an iestetic coloration of the film surface.

 Applied on metal, the coating according to the invention provides an instantaneous protection against corrosion to that accessible by a formulation based on a conventional latex.

Examples
Example 1 Preparation of an Unsaturated Hydrodispersible Polyamide (PAHDI) Monounsaturated with Cinnamic Acid

 It operates in a reactor of 4 liters of capacity, three-pipe: gas inlet, communication with a distillation system comprising a condenser connected to a distillate receiver, and an anchor stirrer.

In this reactor, we introduce:

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339.0 g of lactam 6 is 3.0 mole, 196.5 g of salt AH (adipic acid salt and hexamethylenediamine) is 0.75 mole, 187. 34 g of hexamethylenediamine is 1.615 mole, 168. 5 g of isophthalic acid is 1.015 mole , 161 .0 of monosodium salt of sulpho isophthalic acid is 0.6 mol, and 22. 5 g of cinnamic acid is 0.152 mol which corresponds to one unit of cinnamic acid per PAHDI chain and 50 g of water .

 The reactor is purged with nitrogen, then heated all valves closed up to 200 C material in 1 hour, the pressure is then 6. 0 bar. Then, with stirring, the temperature is raised in 1 hour at 240 C, the pressure is then 15 bar. The reaction is allowed to proceed at 240 ° C. for 4 hours, the pressure reached at the end of the 4 hours at 18 bar and stabilizes, which means firstly that all the monomers react and secondly that the equilibrium of formation of the amides is reached. At this point, the 90-minute expansion is begun, the material temperature at the end of the expansion is 270 ° C. A stream of nitrogen of 30 l / h is passed for 15 minutes and the PAHD is removed from the reactor, collected. in a cooled tray to ensure rapid solification.

 The product obtained is slightly yellow, friable, odorless. The number average molecular weight measured by viscosimetry is 6650 g / mol. The Tg is 89 C (measured by DSC: 10K / min). PAHD is easily dispersible in water up to 40% by weight. The particle size of the dispersion is 62 nanometers.

 Example 2 Preparation of Dispersions According to the Invention

 Example 2.1 Using the PAHDI of Example 1

 In a 20 # jacketed reactor equipped with a condenser and purged with nitrogen, 300 g of a polyamide dispersion, described in Example 1 of the invention, is added to 0.5% solids. .

 The reactor is purged with nitrogen and the temperature is brought to 75 C under 150tr / min. When the temperature is reached and stabilized, 200 g of the monomer mixture consisting of 92.0 g of methyl methacrylate, 104.0 g of butyl acrylate and 4.0 g of acrylic acid and a solution of

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 0.8 g of TBHP initiator (Terbutyl hydroperoxide) in 25 ml of water and a solution of 0.88 g of FORMOPON activator (sodium salt of formaldehyde sulfoxylate) in 25 ml of water are drained in 300 min. After 90 minutes of polymerization, a solution of 1.23 g of SDS in 25 ml of water is poured in 210 min.

 After the end of the addition, the reaction medium is maintained at 75 ° C. for 60 minutes, then cooled to room temperature and filtered through a 100 micron filter. Dry extract and particle size were then determined (Table 1).

Example 3
Formulation
The paint of low CPV, whose formulation is given below, is manufactured according to the invention with an acrylic dispersion on PAHD seed: It is bright and has a good tension. The present formulation does not contain active substances generally introduced to block the rise of water-soluble coloring substances.

Nevertheless, applied on merbau, the coloration of the film is minimal after drying. There is almost no instantaneous corrosion when the paint is applied to degreased steel.

 In comparison, merbau tannin staining and flash corrosion are pronounced when the paint is formulated with standard latex polymerized according to conventional technology. Moreover, functionalized latexes to block the water-soluble ones lend themselves poorly to the formulation of a glossy and taut paint.

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Dispersion <SEP><SEP> Standard <SEP> Acrylic <SEP> on <SEP> PAHD
<tb> with <SEP> surfactants
<tb> Resistance <SEP> to <SEP><SEP> escalation <SEP> of <SEP> Poor <SEP> Good
<tb> tannins
<tb> Difference <SEP> of <SEP> hue <SEP>(#<SEP> E <SEP> Interlab) <SEP> 9. <SEP> 9 <SEP> 7. <SEP> 3
<tb> Corrosion <SEP> Instant <SEP> Pronounced <SEP> Very <SEP> Low
<tb> @
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Claims (9)

1. Use of an aqueous dispersion based on polymer particles containing from 0.1% to 100% by weight of the total weight of the water-dispersible polycondensate particles and from 99.9% to 0% by weight total weight, acrylic, vinyl and / or styrenic polymer particles, for the treatment of surfaces of materials such as paper, textile, wood, leather, metal, glass, building materials.  2. Use according to 1 characterized in that said dispersion preferably contains, from - 0.1% to 40% by weight of the total weight, of the particles of water-dispersible polycondensate and, from - 60% to 99.9% by weight of the weight total, acrylic, vinylic and / or styrenic polymer particles 3. Use according to 1 or 2 characterized in that said polycondensate is selected from polyamides, polyesters, polyesteramides, polyetheresteramides.  4. Use according to claim 3 characterized in that the polycondensate is a polyamide.  5. Use according to one of the preceding claims characterized in that the aqueous dispersion is obtained by mixing the dispersion of the polycondensate and optionally a dispersion of the vinyl polymer, acrylic and / or styrene.  6. Use according to one of the preceding claims characterized in that the aqueous dispersion is obtained by the polymerization in the presence of the water-dispersible polycondensate of at least one vinyl monomer, acrylic and / or styrene.  7. Use according to one of the preceding claims characterized in that the dispersion is formulated with a pigment, and / or <Desc / Clms Page number 16>  fillers, and / or a thickener, and / or other adjuvants to form a film-forming or non-film-forming coating; the dispersion may in particular be formulated with pigments and / or active adjuvants.  8. Use according to one of the preceding claims for preventing the migration of coloring substances from a substrate to be coated; in particular as an inhibitor of tannins in the treatment of wood.  9. Use according to one of the preceding claims as an instantaneous corrosion inhibitor in the treatment of steel.  @