MC200042A1 - Fluoride acrylic terpolymer type anti-graffiti varnish for protecting organic polymer type supports - Google Patents

Abstract

The present invention relates to the preparation of hydrophobic and oleophobic anti-graffiti protective varnishes, with anti-soiling properties for the protection of supports of the organic polymer type such as PVC and PET. These varnishes are prepared by radical polymerisation of a composition containing by weight:[A], 20-90 percent, with respect to the total composition, of a mixture containing, by weight with respect to [A],(a) 10-80 percent of styrene or an acrylate or methacrylate monomer having 1-18 carbon atoms in the alkylated group;(b) 5-60 percent of another hydrocarbon monomer of the acrylate or methacrylate type having 1-18 carbon atoms in the alkylated group;(c) 0.1 to 50 percent of a fluorinated monomer of general formula:<IMAGE>wherein:-RF denotes a linear or branched perfluoroalkyl chain, CmF2m+1 (m = 1-22).-R denotes a hydrogen atom or a linear or branched alkyl group containing 1-4 carbon atoms.-n varies from 1 to 15.(d) 0.2 to 2 percent of radical initiator[B], 0-80 percent by weight with respect to the total composition of polymerisation solvent.The corresponding polymer has a glass transition temperature of between 0 and 100 degrees C, preferably between 20 and 50 degrees C.

Description

DUPLICATE

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2 0 0 0 ^0% 2 u 7 2

PATENT FOR INVENTION

August 3, 2001 #12 14

Title of the invention:

Anti-graffiti varnish of the terpolymer type, fluoroacrylic, for the protection of organic polymer substrates

The invention relates to the formulation and use of hydrophobic and oleophobic fluorinated terpolymers as anti-graffiti protection for PET and PVC substrates and, more generally, for organic polymer substrates.

5 The application of graffiti, whether inscriptions or drawings, on the surfaces of street furniture, building facades or public places leads to the disfigurement and deterioration of these surfaces and generates very significant restoration costs.

Besides mechanical treatments (sandblasting), earlier art employs two main anti-graffiti strategies:

The first "chemical" strategy involves stripping the paints applied to the contaminated surfaces using stain removers such as dichloromethane, methanol, 1-methyl-2-pyrrolidinone, or other more specific stain removers. Any remaining residues are removed by powerful washing or sandblasting. Restoration of the treated surface is then performed.

15, therefore often indispensable. Furthermore, the effectiveness of the treatment is considerably reduced in the case of porous surfaces such as concrete, stone...

The second method falls under the category of prevention and consists of applying one or more layers of paint or varnish to prevent the

Inventors: S. Saidi, F. Guittard, S. Geribaldi, M. Mateu, C. Baudrion

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penetration of graffiti colors into the pores of the substrate. Depending on the resistance of anti-graffiti coatings to external effects, particularly atmospheric effects and stain removers, two categories of protection are described:

- Sacrificial coatings: These are generally based on acrylic resins or waxes. These coatings offer significant advantages such as low toxicity and low manufacturing cost. However, they are very fragile and therefore only effective in the short term, which is not very desirable [M. Vo-Thanh (CASCO Nobel France, FR), FR 2 683 540, 1991; C. Brett (Morton International GmbH), DE 197 43 566 Al, 1997; A. Pierre (AGRIPAX (S.A)), FR 2 686 614, 1992]. 10 - Permanent coatings: These are based on polyurethanes, silicones, or fluoropolymers. These undoubtedly represent the most interesting approach since they combine both hydrophobic (water-repellent) and oleophobic (oil-repellent) properties not found in silicone coatings. They have good resistance to humidity, unlike polyurethanes, and exhibit remarkable surface properties [A. L. Dessaint, M.-J. Lina (Atochem, Courbevoie, Fr), US 4 478 975, 1984; R. Marchetti, P. Voghera, S. Turri (Ausimont SpA, Milano), EP 739 923, 1996; H. Kishita, K. Yamaguchi, T. Takago (Shin-Etsu Chemical Co, LTD, Tokyo), US 4 985 526, 1990].

We opted for this latter approach, which consists of designing a 20% anti-graffiti coating to be applied directly to polymer-type substrates requiring protection. Our working hypothesis is primarily based on the introduction of fluorine. The development of this type of coating must be carried out in such a way as to promote, on the one hand, sufficient adhesion of the anti-graffiti varnish to the substrate to be protected, and on the other hand, to prevent graffiti from adhering to the other side of the coating.

The present invention thus falls within the field of fluorinated acrylic coatings, and more particularly acrylic terpolymers, one of whose monomers is a fluorinated acrylate. This varnish is used primarily as a hydrophobic and oleophobic anti-graffiti agent, with anti-adhesive and anti-fouling properties for various polymer substrates. Non-limiting examples of substrates to be protected include: polyethylene, polyvinyl chloride (PVC), polyacrylates, polymethacrylates, polypropylene, polyamides, polyurethanes, acrylonitrile butadiene styrene (ABS), and saturated or unsaturated polyesters such as...

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polyethylene terephthalate (PET), polycarbonates, polyacrylamides, Teflon (PTFE), polysiloxanes, polysaccharides.

According to the invention, the varnishes are obtained by radical polymerization of a composition containing by weight:

*[A] of 20 to 90% by weight relative to the total composition, of a mixture containing by weight relative to [A]: ;(1)- of 10 to 80%, preferably of 40 to 70%, of styrene or of an acrylate or methacrylate type monomer having 1 to 18 carbon atoms in the group;(2)- of 5 to 60%, preferably of 15 to 30%, of another acrylate or methacrylate type monomer having 1 to 18 carbon atoms in the alkylated group; ;(3) from 0.1 to 50%, preferably from 3 to 40% of fluorinated monomer of general formula: ;in which: ;♦ Rf denotes a linear or branched perfluoroalkyl chain CmF2m+i (m = 1 ;25 *[B] of 0 to 80% by weight relative to the total composition, preferably from 25 to 40% of polymerization solvent.

The fluorinated monomers (3) are prepared by conventional methods, for example by esterification of acrylic or methacrylic acid with the corresponding perfluoroalkyl alcohol, in the presence of an acid catalyst such as sulfuric acid or paratoluenesulfonic acid. The corresponding acid anhydrides and chlorides can also be used instead of the organic acid. Monomers (1) and (2) are selected from alkyl acrylates or methacrylates.

10 alkylated;

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20 to 22)

♦R denotes a hydrogen atom or a linear or branched alkyl group

containing 1 to 4 carbon atoms;

♦n varies from 1 to 15, preferably from 2 to 8;

(4)- from 0.2 to 2%, preferably from 0.4 to 1%, of radical initiator;

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containing 1 to 18 carbon atoms in the alkyl group, such as: methyl acrylate, ethyl acrylate, butyl acrylate, isopropyl acrylate, or stearyl acrylate. Other non-acrylate or methacrylate monomers may be used, for example: styrene, alpha-methylstyrene, or alpha-cyanomethylstyrene.

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The composition described above is polymerized by conventional solution or bulk polymerization techniques. When polymerization is carried out in solution, the solvents used are aliphatic hydrocarbons such as heptane, or aromatic hydrocarbons such as benzene, toluene, xylene; ketones such as acetone, methylethyl ketone, methylisobutyl ketone; esters such as butyl or ethyl acetate; ethers such as dimethyl or diethyl ether, ethylene glycol, dipropyl or dibutyl ether; halogenated hydrocarbons such as 1,1,1-trichloroethane, trichloroethylene, perchloroethylene; fluorinated solvents such as Freon 113; or other solvents such as acetonitrile, n-15 methylpyrolidone, or mixtures of these solvents.

Several methods of adding monomers are possible:

- in "one pot": the 3 monomers, the radical initiator and the solvent are placed in the reactor and then heated to the polymerization temperature;

- the 3 monomers and the radical initiator can be added drop by drop 20 into the polymerization solvent previously heated to the polymerization temperature.

- The hydrocarbon monomers and the initiator are first added dropwise to the solvent, then towards the end of the addition, the fluorinated monomer is added all at once to the reaction mixture. This latter method of addition allows access to more complex materials

25 efficient [R. R Thomas, D. R. Anton, W. F. Graham, M. J. Darmon, B. B. Sauer, K. M. Stika, D. G. Swartzfager, Macromolecules, 30, 2883, 1997].

The reaction temperature varies between room temperature and the boiling point of the reaction mixture, preferably between 80° and 100°C. The radical initiators used are azo compounds such as azo-bis-30 isobutyronitrile (AIBN), 1,1'-azo-bis(cyanocyclohexane), azodicarbonamide, or peroxides such as ditert-butyl peroxide, peroxide acetates such as tert-butyl peracetate, or benzoates such as tert-butyl perbenzoate, or octoates such as tert-butyl peroctoate. The amount of initiator used varies

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from 0.2 to 2%, preferably from 0.4 to 1% relative to the total weight of the monomers. The reaction can also take place by UV irradiation in the presence of photoinitiators such as benzophenone.

The weight of the polymers obtained is determined by gel permeation chromatography using polystyrene as a standard and THF as the eluent. Average weights ranging from 10,000 to 150,000 are obtained.

Polymers have a glass transition temperature between 0° and 100°C, preferably between 20° and 50°C.

Once the polymer is obtained, it can be deposited as is, without being isolated from the reaction medium. In this case, the polymerization solvent is used as the deposition solvent. Alternatively, it can be isolated from the reaction medium by precipitation in a solvent such as methanol, and then deposited pure or in solution in a solvent other than the polymerization solvent. If the polymer is deposited in solution, various additives can be added to the formulation, such as UV stabilizers like benzophenones, antioxidants, thixotropic agents, pigments, etc.

The formulation is thus deposited in one or more layers using conventional coating methods such as brush, paintbrush, spray gun, or electrodeposition. It is then dried at a temperature between 50° and 150°C, preferably between 60 and 100°C, for 0.5 to 8 hours.

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The present invention will be better understood with the aid of the following additional description. The following examples illustrate the present invention without, however, limiting it.

Example 1:

25. In a reactor equipped with a stirrer, a condenser, and a thermometer, 1.6 mL of acetonitrile is placed. After purging the apparatus with nitrogen, the mixture is heated to 80°C. 0.85 g (6.64 mmol) of butyl acrylate and 2 g (20 mmol) of methyl methacrylate are added dropwise over 40 minutes. Simultaneously, 0.1723 g (0.105 mmol) of AIBN diluted in 0.25 mL of acetonitrile is added dropwise over 30 minutes. Five minutes before the end of the monomer addition, 0.1 µg is added all at once.

(0.26 mmol) of CsF₂COCH₂C₂(Al) monomer is diluted in 0.1 ml of acetonitrile. After the addition of the monomers is complete, 0.66 ml of acetonitrile is added. The mixture is then stirred at 80°C for 2 hours to ensure the...

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total conversion of monomers.

The mixture is then cooled to room temperature, and the polymer is precipitated by the addition of methanol. It is subsequently subjected to several washing/centrifugation cycles and then dried under reduced pressure. This yields a white solid 5 whose average weight, determined by gel permeation chromatography relative to polystyrene as a standard, is 46,000.

A solution of this polymer and an organic solvent such as acetone at a concentration of 0.15 g/ml is deposited onto PET and dried at 60°C for 6 hours. This yields a transparent film with a thickness of approximately 1.5 µm. The contact angles, θ, of this film are measured using water, CH₂I₂, and hexadecane as wetting solvents. The surface tensions and the polar and nonpolar components of the first two solvents are used to calculate the surface energy using the Owens-Wendt-Fowkes method. The results obtained are summarized below:

15 Beau = 99°; 0ch2i2 = 64°C; hexadecane = 43°; Surface energy (mN/m) = 26.44

Example 2:

The amount of monomer (Al) is increased to 1.11 g (2.66 mmol) in composition 20 described in Example 1. The polymerization and processing conditions are maintained identical to those of Example 1. A polymer with a mass of 55,000 relative to polystyrene, taken as the standard, is obtained. The results obtained are as follows:

0water = 112°; ©ch2i2 = 97°; 0hexadecane = 74°; Surface energy (mN/m) = 10.29

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Example 3:

In the formulation described in example 1, the Al monomer is replaced by 0.118g

(0.266 mmol) of monomer A2 with the general formula: CgFi7(CH2)40C0CH=CH2. The polymerization, processing, and deposition conditions are maintained identically to those of Example 1. A polymer with a mass of 60,000 relative to polystyrene, taken as the standard, is obtained. The following results are obtained:

©water = 98°; 0CH2I2 = 63°; ©hexadecane = 33°; Surface energy (mN/m)= 26.89.

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Example 4:

In the formulation described in Example 1, the monomer Ai is replaced by 0.126 g (0.266 mmol) of monomer Ai with the general formula: CgFi7(CH2)60COCH=CH2. The polymerization, processing, and deposition conditions are maintained identical to those of Example 1. A polymer with a mass of 45,000 relative to polystyrene, taken as the standard, is obtained. The following results are obtained:

©water = 90°; eCH2I2 = 61°; 0hexadecane = 26°; Surface energy (mN/m) = 28.79.

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Claims (1)

DEMANDS 1) Varnishes obtained by radical polymerization of a composition containing by weight: *[A]- from 20 to 90% by weight relative to the total composition, of a mixture containing by weight relative to [A]:;(a)- from 10 to 80% of styrene or of an acrylate or methacrylate hydrocarbon monomer having 1 to 18 carbon atoms in the alkyl group;;(b)- from 5 to 60% of another acrylate or methacrylate hydrocarbon monomer having 1 to 18 carbon atoms in the alkyl group;;(c) from 0.1 to 50% of a fluorinated monomer of general formula:;in which:;♦ R/r denotes a linear or branched perfluoroalkyl chain CmF2m+i (m = there;♦R denotes a hydrogen atom or a linear or branched alkyl group containing 1 to 4 carbon atoms;;♦n varies from 1 to 15;;(d)- from 0.2 to 2% of radical initiator ;;*[B] from 0 to 80% by weight relative to the total composition, of polymerization solvent. 2) Compositions according to claim (1), in which R/r = C4F8, CgF^ and C8F17- 3) Coating compositions according to claim (1), wherein n = 2, 22) 4 and 6. 4) Compositions according to claim (1) containing 40 to 70% of hydrocarbon monomer (a), 15 to 30% of monomer (b), 3 to 40% of fluorinated monomer (c), 0.4 to 1% of at least one initiator and 25 to 40% polymerization solvent. 9 0.4 to 1% of at least one initiator and 25 to 40% polymerization solvent. 5) Polymers obtained according to claim (1) having a glass transition temperature between 0° and 100° preferably between 20° and 50°C. 5 6) Use of the varnishes obtained according to claim (1) as anti-graffiti, anti-fouling, anti-sticking agents, and hydrophobic and oleophobic treatment agents for organic polymer type surfaces. 10 7) Application of the varnishes obtained according to claim (1), onto the substrate to be protected, either pure or in solution in the polymerization solvent or in a solvent other than the polymerization solvent 8) Varnish according to claims 1 to 6 characterized in that the substrate to 15 protect is an organic plastic including polyethylene, polyvinyl chloride (PVC), polyacrylates, polymethacrylates, polypropylene, polyamides, polyurethanes, acrylonitrile-butadiene-styrene (ABS), saturated or unsaturated polyesters such as polyethylene terephthalate (PET), polycarbonates, polyacrylamides, Teflon (PTFE), polysiloxanes, polysaccharides. 20 25 30