CZ20011709A3 - Coating compositions - Google Patents

Abstract

A coating composition comprises a solvent, an alkyd resin, and a vinylic star polymer comprising the residue of a polyfunctional thiol compound having at least three functional thiol groups and at least three vinylic chains each comprising the residue of at least one monofunctional vinylically unsaturated monomer. The vinylic star polymer is soluble in the alkyd resin solution and produces solutions of relatively low viscosity compared to linear acrylic polymers.

Description

Paints

Technical field

The invention relates to paints, in particular paints containing alkyd resins, which are used, for example, in solvent paints.

BACKGROUND OF THE INVENTION

Alkyd resins are polyhydroxyl alcohols and acids, long chain fatty acids, oils and widely used as protective wood coatings It is common to modify with long naturally occurring glycerin. industrial applications

They are eg.

colors.

polyesters which are often derived from alcohols in many such as paint or alkyd resins solvents or resins due to other compounds, eg phenolic increased hardness and because of resistance to epoxy resins due to increased adhesion and silicones for increased temperature resistance and resistance to thermal shocks. A detailed description of alkyd resin modifiers can be found, for example, in "Encyclopaedia of Polymer Science and Technology 1st Edition, Vol. 1, p. 663 (Wiley 1964). Acrylic compounds are also used as alkyd resin modifiers, for example, to improve durability, improve color and color fastness, enhance gloss and improve gloss fastness, and shorten the drying time of the coating. For the purpose of modification, the modifying resin must be miscible with alkyd resins and soluble in a carrier system such as white spirit or xylene. Among the thermoplastic acrylic resins are low molecular weight linear polyisobutyl methacrylate polymer resins known to have good solubility in white spirit and good miscibility with alkyds, and are preferred for commercial use as alkyd modifiers compared to other thermoplastic acrylic resins.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a coating composition comprising a solvent, an alkyd resin and a vinyl star polymer comprising a polyfunctional thiol compound residue having at least three functional thiol groups and at least three vinyl chains, each comprising at least one monofunctional vinyl unsaturated monomer such as alkyl acrylate. or alkyl (alk) acrylate.

In another aspect, the invention provides a vinyl star polymer comprising a polyfunctional thiol compound moiety having at least three functional thiol groups and at least three vinyl chains, each comprising at least one monofunctional vinyl unsaturated monomer such as an alkyl acrylate or an alkyl (alk) acrylate as a coating component. based on alkyd resin.

In another aspect, the present invention provides a process for the manufacture of paints comprising forming a solution or dispersion of an alkyd resin in a solvent and then adding a vinyl star polymer comprising a polyfunctional thiol compound residue having at least three functional thiol groups and at least three vinyl chains, each comprising at least one monofunctional vinyl unsaturated monomer such as an alkyl acrylate or an alkyl (alk) acrylate; and mixing the resulting mixture to affect the polymer solution.

Polymers having " star polymers "

• to • described compositions are • to • this to to · to · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Acrylic.

known as due to their morphology in shape are described with both alkyd modifiers and three acrylic chains arranged from a thiol. Star polymers compatibility use in WO-A-96/37520. However, their resins and their resins for alkyd resin systems were not the same as before

The star polymers described have been described and are unexpected.

improved solubility in solvents used in the production of alkyds such as white spirit, as well as providing increased miscibility with alkyd resins compared to some known acrylate-type alkyd resin modifiers. These features can provide advantageous effects, e.g., coating compositions having a lower application viscosity or having a higher content of acrylic modifiers in the alkyd resin.

The vinyl polymer comprises a head portion of a polyfunctional thiol compound. The head derived from the portion comprises a core group X and at least three linker groups Y-S. X is preferably at least a portion of the tri- to hexafunctional alcohol residue of dipentaerythritol such as glycerin, sorbitol, pentaerythritol, tripentaerythritol, trimethylolethane, pentahydroxypentane. trichinoyl and inositol.

is preferably an alkylate, in particular a C ₂ to C 10 alkylate, and in particular trimethylolpropane,

Coupling unit

_C2 to _C6 alkyl;

The head portion is preferably a tri- to octa-functional residue, in particular a tri- to hexafunctional mercaptan. The mercaptan may be an ester formed from an alcohol and a thio-C 2 to C 10 alkanoic acid, in particular a thio-C 2 to C ₆ alkanoic acid. Examples of suitable acids are 2-mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, 4-mercaptobutanoic acid, 5-mercaptopentanoic acid, 6-mercaptohexanoic acid and 10-mercaptodecanoic acid. acid. Preferably, the acid is 2-mercaptoacetic acid or 3-mercaptopropionic acid.

Examples of suitable polyfunctional mercaptans include trimethylolethane tris (3-mercaptopropionate), pentaerythritol tetra (3-mercaptopropionate), pentaerythritol tetrathioglycolate, trimethylolethane trithioglycollate, trimethylolpropane tris (3-mercaptopropionate), mercaptopropionate), dipentaerythritol hexathioglycolate, tripentaerythritol octa (3-mercaptopropionate), tripentaerythritol octathioglycolate.

Mixed polymer systems may be made by selecting more than one type of head compound, eg, by polymerizing acrylic monomers to form chains in the presence of more than one polyfunctional thiol compound or one or more polyfunctional thiol compounds and one or more monofunctional or difunctional thiol compounds. Suitable monofunctional thiol compounds include propyl mercaptan, butyl mercaptan, hexyl mercaptan, octyl mercaptan, dodecyl mercaptan, thioglycolic acid, mercaptopropionic acid, 2-ethylhexyl thioglycollate, mercaptoethanol, mercaptooleate acid, thiocapoundecanoic acid, thiocapoundecanoic acid; 3-mercapto5 propionate), ethylene bis (3-mercaptopropionate), polyethylene glycol dimercaptoacetates

Star polymer blends may be formed from such blended polymerizations or simply by mixing more than one type of preformed star polymer resin or one or more preformed star resins with one or more linear vinyl polymers. Such compositions can be used very effectively in the coating compositions of the present invention. The vinyl chains of each vinyl star polymer or linear polymer may be formed from vinyl monomer compounds that are either the same or different from the vinyl star polymer or linear polymer in the blend.

The vinyl polymer chain is formed from at least one mono-olefinically unsaturated monomer, which may be selected from any of the mono-olefinically unsaturated monomers known in the art. '

Suitably, methacrylic monofunctional vinyl unsaturated monomers may be selected such as acrylic.

of the monomers is an acrylic .typu CHC1COOH = _CH2), acrylamide and methacrylamide, alkoxyalkyl, acrylamides and methacrylamides, acrylonitrile and methacrylonitrile, e.g. butoxymethyl acrylamide and methoxymethyl methacrylamide, hydroxyalkyl acrylamides methacrylamides, e.g. N-methylol acrylamide and methacrylamide, the metal acrylates and methacrylates' and acrylic, methacrylic and chloroacrylic acid esters with alcohols and phenols; vinylaromatic compounds such as styrene and substituted derivatives thereof such as its halogenated derivatives and vinyltoluene; vinyl esters such as vinyl acetate and vinyl pyrrolidone.

Preferred monofunctional vinylically unsaturated monomers include acrylic or methacrylic acid and esters thereof having the formula CH ₂ = C (R) COOR ^2, wherein R is H, methyl or butyl, especially methyl, isobutyl and n-butyl and R ² is an optionally substituted hydrocarbyl (e.g., optionally halo- or hydroxy-substituted hydrocarbyl) and in particular is a C 1 -C ₁₀ alkyl, C ₈ -C 10 cycloalkyl or C ₆ -C ₁₀ aryl group. Particular examples of such monomers include unsubstituted esters of acrylic and methacrylic acids such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, benzo methacrylate, methacrylate and isobornyl acrylate; and substituted acrylic and methacrylic acid esters such as hydroxyethyl methacrylate and hydroxypropyl methacrylate. More specifically, the monofunctional vinyl unsaturated monomer is a C ₁ -C ₈ alkyl ester of methacrylic acid. Methyl methacrylate, isobutyl methacrylate and n-butyl methacrylate are particularly preferred monomers.

At least three vinyl polymer chains may be formed from a mixture of monofunctional vinyl unsaturated monomers, eg, a mixture of monomers described above.

Each vinyl-unsaturated polymer chain may typically be comprised of 10 to 1500 monomer units, e.g., 25 to 1500 monomer units, preferably 20 to 800 monomer units, and in particular 30 to 800 such monomer units. Preferably, the copolymer is a random copolymer as formed by conventional free radical polymerization.

Each vinyl polymer chain may be formed using polythiol as a chain transfer agent by a polymerization process conventionally used for the preparation of poly (methacrylates). This process involves block polymerization,. solution polymerization and suspension polymerization of acrylic polymer chains. Preferred processes are suspension polymerization and block polymerization.

Suspension polymerization is typically carried out, at least initially, in the range of 10 to 120 ° C, preferably in the range of 50 to 110 ° C, especially in the range of 70 to 110 ° C, and particularly preferably at 75 to 100 ° C. Suitable block polymerization processes are carried out at temperatures of from 70 to 130 ° C.

Preferred processes are block, solution, emulsion and suspension polymerizations using free radicals.

Suitable free radical initiators include organic peroxides, hydroperoxides, persulfates, and azo compounds. Examples of such initiators are methyl ethyl ketone peroxide, benzoyl peroxide, cumene hydroperoxide, potassium persulfate, azobisisobutyronitrile (AIBN), lauroyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, diethylperoxide, dipropyl peroxide, dilauryl peroxide, dioleyl peroxide, dioleyl peroxide ) peroxide, di (tert-amyl) peroxide, tert-butyl · hydroperoxide, tert-amyl hydroperoxide, acyl peroxide, propionyl peroxide, lauroyl peroxide, stearoyl peroxide, malonylperoxide, succinylperoxide, phthaloylperoxide, acetylbenzoyl peroxide, propylbenzoyl peroxide, propylbenzoyl peroxide, sodium percarbonate, potassium percarbonate, sodium perborate, potassium perborate, sodium perphosphate, potassium perphosphate, tetralin hydroperoxide, tert-butyldiperphthalate, tert-butylperbenzoate, 2,4-dichlorobenzoylperoxide, ureaperoxide, caprylylperoxide bis, t-chlorobenzoyl peroxide butane, hydroxyheptyl peroxide.

An initiator to polythiol ratio of less than 6: 1 (molar) is preferred, e.g. in the range. 6: 1 to 1: 6, and a particularly preferred ratio of initiator to polythiol is less than 3: 1 molar, e.g. in the range of 3: 1 to 1: 3. A molar ratio of polythiol to monomer in the range of 1:10 to 1: 3000 is preferred, and a particularly preferred molar ratio of polythiol to monomer is in the range of 1:25 to 1: 1500.

When the polymerization process is an emulsion polymerization, the emulsifier may be selected from emulsifiers commonly used in the art. These emulsifiers include fatty acid soaps, partially saponified rosin, sodium lauryl sulfate, polyethoxyalkylated phenols, dioctyl sodium sulfosuccinate and dihexyl sodium sulfosuccinate.

If the polymerization process requires a solvent, the solvent may be selected from solvents commonly used in the art, such as benzene, toluene, xylene, aliphatic esters, aliphatic ethers, aliphatic ketones and aliphatic alcohols.

The molecular weight of the polymer is. controlled by the mercaptan used to produce the head portion of the star polymer.

The molecular weight (Mw) is. usually in the range of 4000 to

80000 Dalton, preferably from 8000 to 60000 D ..

φφ.φ ·

ΦΦΦ · φφφ

The acrylic polymer may be present in the coating composition in concentrations of from 1 to 80% by weight, preferably from 1 to 60% by weight. The weight ratio of acrylic polymer to alkyd resin is typically in the range of 1: 8 to 1: 2.

Coating typically resin, acrylic components. These additional resin coating solution resins include desiccants, zinc, zirconium or in concentrations of from 0.1 to containing, in addition to alkyd and solvents, other formulations.

such as

well-known cobalt salts, lead, calcium,

1.0% by weight of the alkyd resin normally present in the coating. The coating may also contain pigments and opacifiers, such as titanium dioxide. When used, the pigments may be present at concentrations such that the pigment to binder weight ratio is between 1:20 to 1.2: 1.

Typical solvents in such coatings are white spirit. The total solids content (i.e., non-volatile components) of white spirit is typically in the range of from 40 to 50 wt%.

The coating compositions may also contain other ingredients not mentioned above and which may be known in the art of solvent coating formulations.

The invention will be further described by way of examples.

• 0 ·· Φ ···

DETAILED DESCRIPTION OF THE INVENTION

Example 1. Preparation of a blended star polymer

The suspending agent (4.5 g, Natrosol HEC 250LR, obtained from Aqualon Inc, Hercules Inc) was dissolved in a 5 L flask in 2.0 L of deionized water by heating at 40-50 ° C for 30 minutes under nitrogen. atmosphere with gentle stirring. The pre-blended monomer phase was made from 500 g of i-butyl methacrylate, 1.75 phm (parts per hundred parts of monomer) of dodecyl mercaptan (DDM), 1.75 phm of trimethylolpropane tris (3-mercaptopropionate) (TRIMP) and 1 75 phm pentaerithritol tetra (3-mercaptopropionate) (PETMP). The AIBN initiator (5.0 g) was added to deionized water under a connected water condenser under a nitrogen atmosphere. The temperature was raised to 76 ° C and the mixture was stirred at 1500 rpm. The polymerization proceeded to almost complete conversion of the monomer to polymer, after which the cooling water in the condenser was stopped. The polymer was then exposed to a higher temperature ranging from 90 to 95 ° C for 30 minutes to complete polymerization and remove unreacted monomer. After heat treatment, the nitrogen atmosphere was removed and the polymer was cooled in air. The cooled polymer was then filtered, washed with deionized water and dried.

The molecular weight of the polymer was measured using gel permeation chromatography (GPC) using chloroform as solvent and polymethyl methacrylate standards. The results are summarized in Table 1. The polymer was dissolved in white spirit, the viscosity of the resulting solution was measured, and the results are shown in Table 2. Commercial thermoplastic solid polyisobutyl methacrylate alkyd solution (labeled) in the following table as CR) having a molecular weight Mw = 9550 and Mn = 4750 was used for

demonstration effects known modifiers ve comparison with polymers of Přídů 1 and 2. Example 2. Preparation star polymer se medium molecular weight It was pou live the way preparation from Example 1 p tou exemption,

that DDM was omitted.

Example 3 (Comparative). Preparation of linear polymer

The preparation method of Example 1 was used except that the only mercaptan used was DDM at a concentration of 1.75 phm.

The results show that the polymers described in Examples 1 and 2 are soluble in white spirit and produce solutions of relatively low viscosity up to a concentration of 30% w / w. In contrast, the linear control polymer (Example -3) is not completely soluble in white spirit.

It can also be seen that for a given viscosity, the resins of Examples and 2 have the additional advantage of being able to dissolve to a higher solids content (e.g.

to be able to use less solvent) than it is. this is the case with polyisobutyl methacrylate resin.

Table 1

Example Mercaptan (s) Mw Mn d 1 1.75 phm DDM, TRIMP and PETMP 9450 5250 1.79 2 1.75 phm TRIMP and PETMP 14100 8700 - 1.63 3 (compare) 1.75 phm DDM 15500 7 650 2.03 CR 9550 4750 2.00

····

Table 2

Brookfield viscosity (cP) at lab. temperature Polymer 10% w / w 20% w / w 30% w / w Example 1 2.5 5 14.5 Example 2 4,5 8 23.5 Example 3 CR 9 23 152.5

Example 4. Miscibility with alkyd resins

1.0 g of each polymer of Examples 1 to 3 and polyisobutyl methacrylate resin was added to a 9.0 g solution of each of the various commercial alkyd resins. Each sample was then placed in a water bath at 90 ° C and stirred occasionally for 6 hours. After cooling to room temperature, the degree of solubility was estimated visually and classified according to the following distribution:

A: Clear solution - contains no undissolved particles

B: Clear solution - very little undissolved substances C: Cloudy solution - small amount settled undissolved resin D: Cloudy solution - large amount settled undissolved

resin.

The results are summarized in Table 3.

These results show that star polymers and polymers with a partially star structure of Examples 1 and 2 have miscibility with alkyd resins at least as good as the known polyisobutyl methacrylate alkyd modifier. The linear polymer of Example 3 is generally less miscible with these alkyds.

Table 3

Type of alkyd Commercial designation of alkdyd Type of solvent Acid number Polymer CR 1 O z. 3. Long soybean oil Wresinol AS621 65% in white spirit 10 max D (B) AND' C Long linseed oil Wresinol AL668 65% in white spirit 10 max AND AND AND (B) Medium soybean oil Wresinol AS483 50% · in white spirit 14 max (B) AND C C Short soybean oil Blagden Chemicals K674-50x 50% in white spirit 30 max D (B) D D Long soybean oil Blagden Chemicals 1426 65% in white spirit 10 max AND AND (B) C ' Medium linseed oil Blagden Chemicals 830-40 40% in white spirit 10 max (B) AND (B) C

φ φφφ

Claims (12)

PATENT CLAIMS · φ φ · · • · φ φ φ • • • • • • • • • · · · · · · · · · · · · · · 1. A coating composition comprising a solvent, an alkyd resin, and a vinyl star polymer comprising the remainder of a polyfunctional thiol compound having at least three functional thiol groups and at least three vinyl chains. wherein each comprises a residue of at least one monofunctional vinyl unsaturated monomer. The coating composition of claim 1, wherein the polyfunctional thiol compound comprises a head portion having a core X and at least three linker groups Y-S, wherein: X is at least part of the tri- to hexafunctional alcohol residue and the linker group Y is an alkylate. The coating composition according to claim 2, wherein the multifunctional alcohol is selected from the group consisting of dipentaerythritol, glycerin, tripentaerythritol, sorbitol, trimethylolethane, trimethylolpropane, pentahydroxypentane, trichinoyl and inositol. Paint according to claim 2, characterized in that the linker group Y is a C-2 to C 10 alkylate. Coating composition according to claims 1 to 4, characterized in that said vinyl star polymer is a mixture of more than one vinyl star polymer comprising residues of different polyfunctional thiol compounds having at least three functional thiol compounds and at least three vinyl chains wherein the vinyl chains of each vinyl star polymer are formed from a vinyl monomer blend that is either the same or different for each vinyl star polymer. Coating composition according to claims 1 to 5, characterized in that: characterized in that said coating composition further comprises a linear vinyl polymer comprising residues of a vinyl monomer mixture which is either the same or different from the vinyl monomer mixture from which the vinyl chains of each vinyl star polymer are formed. 7. The coating composition of claim 7 wherein said linear vinyl polymer comprises at least one thiol compound having one or two functional thiol groups. Coating composition according to claims 1 to 7, characterized in that said at least one monofunctional vinyl unsaturated monomer is selected from the group consisting of acrylic monomer types, acrylamide methacrylamide, acrylonitrile, methacrylonitrile, alkoxyalkyl acrylamides and methacrylamides, hydroxyalkyl acrylamides and methacrylamides, metal acrylates and methacrylates, acrylic, methacrylic and chloroacrylic acid esters with alcohols and phenols; vinylaromatic compounds and substituted derivatives thereof; and vinyl esters or mixtures of the aforementioned compounds. Coating composition according to claim 8, characterized in that said at least one monofunctional vinyl unsaturated monomer is selected from the group comprising acrylic and methacrylic acid and their esters having the formula CH ₂ = C (R) COOR ² , wherein R je.H, methyl or butyl and R ² is optionally • · «φφφ substituted Ci to Cg alkyl, C ₆ to C _i0 cycloalkyl or C _s to Clc aryl group. 10. The coating composition of claim 9 wherein said at least one monofunctional vinyl unsaturated monomer is a mixture of at least two acrylic or methacrylic acid esters. Use of a vinyl star polymer comprising a polyfunctional thiol compound residue having at least three functional thiol groups and at least three vinyl chains, each comprising a residue of at least one monofunctional vinyl unsaturated monomer, as a component of a alkyd resin based paint. 12. A process for the manufacture of a coating composition comprising forming a solution or dispersion of an alkyd resin in a solvent, then adding a vinyl star polymer comprising a polyfunctional thiol compound having at least three functional thiol groups and at least three vinyl chains comprising a residue at least one monofunctional vinyl unsaturated monomer, and thereafter mixing the resulting mixture optionally with other components selected from the group consisting of drying compounds, pigments, opacifiers to affect the acrylic polymer.