EP0387310A1

EP0387310A1 - Removable waterborne temporary coating

Info

Publication number: EP0387310A1
Application number: EP89906508A
Authority: EP
Inventors: Daniel J. Dotson; Roger E. Hayner
Original assignee: Ashland Oil Inc
Current assignee: Ashland LLC
Priority date: 1988-07-27
Filing date: 1989-05-09
Publication date: 1990-09-19
Also published as: WO1990001051A1; AU3699089A; KR900701943A; AU616536B2

Abstract

Est décrit un revêtement protecteur provisoire à émulsion pour la protection des véhicules durant leur transit depuis le constructeur jusqu'au concessionnaire. Des combinaisons comprenant des émulsions acryliques, des cires, des solvants, des inhibiteurs de corrosion, des antimousses, des amines et des tensioactifs assurentn une protection provisoire aux substrats peints et non peints et s'éliminent aisément sans paraffine ou vapeur. De même, étant à émulsion et s'éliminant à l'aide de nettoyants alcalins, ils ne sont pas nocifs pour l'environnement.A temporary protective emulsion coating is described for the protection of vehicles during their transit from the manufacturer to the dealer. Combinations including acrylic emulsions, waxes, solvents, corrosion inhibitors, defoamers, amines, and surfactants provide temporary protection to painted and unpainted substrates and are easily removed without paraffin or vapor. Likewise, being emulsified and being eliminated using alkaline cleaners, they are not harmful to the environment.

Description

CROSS REFERENCES TO RELATED APPLICATIONS

USSN 124,655 (Attorney Docket 6255AUS) filed November 24, 1987 relates to the general field of the invention.

BACKGROUND

1. Field of the Invention

The present invention relates to the field of corrosion resistant coatings, more particularly water based coatings for temporary protection of painted surfaces and easy removability. A major application iε the protection of painted surfaces of automobiles during transit from manufacturer to distributor, including international transportation. Such compositions are sometimes called "transit waxes".

2. Prior Art

Various water-based compositions taught in the prior art, e.g. U.S. 4,659,380, U.S. 4,444,802, U.S. 4,444,803 all to Winters and Savell produce coatings for the protection of metal from corrosion.

Other waterborne coatings, e.g. U.S. 4,315,957 to Hereth et al. (Hoechst), utilize wax in waterborne formulations for protective coatings.

Some prior formulations are intended specifically for automobile permanent coatings, e.g. Japanese patent applications 62132-569-A and 62132-568-A (Kansai Paint KK) both of which use radiation to cure compositions containing radical polymerisable unsaturated compounds, such as epoxy resins and waxes. Agueous wax dispersions for preserving metal and lacquer are taught by West German patent DE 3512564 Al, 16 October 1986 to Ziegler et al. BASF AG).

All of the above coatings are basically permanent coatings and do not fill the object of the present invention to provide a temporary coating for protecting surface of automobiles, etc. temporarily, during transit.

Temporary coatings are taught by Kawabata (Nippon Oil) U.S. 4,442,140 which teaches compositions containing oxygen-containing wax, emulsifying agent, talc or other silica, other solid pigment or filler. U.S. 4,442,140 compositions tend to flake off and stain as noted at its column 1, line 33-37.

U.S. 4,594,109 also to Kawabata (Nippon Oil) comprising oxygen-containing wax, polybutane, silicone oil, various fillers and an emulsifier. The use of silicone oil precludes any over-spraying, e.g. to cure minor defects or pitting damage during transit.

Therefore, neither of these formulations is well-suited to protection of automotive coatings, even though these compositions are designed to be removable.

Even with those formulations which are water-based and which are designed for reasonably efficient removal of the temporary coating, many require removal with hot steam and solvents, e.g. kerosene, others particularly those employing wax will cause difficulty in removal and possible staining of the undercoating. Others, e.g. water-based amine-containing compositions, can cause softening of the permanent coating which they are intended to protect. Most waxy formulations provide only a hazy or opalescent finish, detracting substantially from the appearance of the automobile or other coated object which they are protecting and may obscure vision through the windshield during drive-on, drive-off operations. As mentioned above, some formulations have prevented over-coating, particularly those formulations which contain silicone. Many wax-containing (water-or solvent based) formulations present a soft waxy film which retains dirt, creating unsightly appearance after long transportation. Solvent based formulations generally present health hazards in the work place where they are applied and removed as also do coatings which require steam and solvent combinations for their removal.

SUMMARY

1. General Statement of the Invention:

According to the present invention, it has been discovered that waterborne, optionally clear, protective coating for protection of new vehicles in transit and the like which is easily removable without harm to the underlying permanent coating can be formulated from: acrylic emulsions, preferably alkali soluble acrylic emulsions, amines, particularly aqueous ammonia and amines such as morpholine, triethylamine/triethanolamine (TEA), dimethylethanolamine (DMEA) , diethylaminoethanol (DEAE), 2-amino, 2-methyl -1- propanol (AMP 95).

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a bar graph of comparative Weatherometer test results of the invention versus several comparative conventional formulations as set forth in the Examples. Figure 2 is a schematic of an article of manufacture comprising a painted metal substrate coated with a composition of the invention.

DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

STARTING MATERIALS

Acrylic Emulsions

Preferably the compositions of the present invention will include acrylic emulsions, and more preferably those which are alkali soluble. A preferred acrylic emulsion having film forming characteristics at ambient temperatures and a glass transition (Tg) of 5-40°C. Non-volatile content should be in the range of about 30-50% by weight. Acid value of the acrylic should be in the range of about 75-150 which allows for alkali solubility.

Preferred commercial acrylic emulsions would include Neocryl BT520 from Polyvinyl Chemical and Carboset 514H or XPD-1214 from B.F. Goodrich.

The amount of acrylic emulsion to be utilized for the present invention is not narrowly critical. For most formulations, the acrylic resin content will be from about 0.5 to 90, more preferably from about 10 to about 60, and most preferably from about 20 to about 60% by weight.

All percents given herein are percents by weight based on the weight of the total formulation unless otherwise expressly stated. These percents assume average concentration and, of course, can be greater reduced by over-dilution with water and/or co-solvents without departing from the spirit of the invention.

Amine

The term "amine" as used herein, includes aqua ammonia. Aqua ammonia (preferably 28° Be) is the most preferred "amine" for purposes of the present invention. Other amines usable include morpholine, triethanolamine, dimethylethanolamine (DMEA) , diethylaminoethanol (DEAE), preferably supplied commercially as "AMP-95", or others commercially available and used by those skilled in the art.

The amine will be present preferably in about 0.1-20 parts by weight, more preferably 1.0-10, and most preferably about 1-5 parts by weight. The most preferred amine is about 1-5 parts by weight of aqueous ammonia (28° Be).

Cosolvents

Cosolvents are desirable, though not absolutely necessary, because they assist in rapid drying. Preferred cosolvents are alcohols, e.g. ethanol, Isopropanol or isobutanol; glycol ethers e.g. butyl cellosolve, cellosolve, methyl cellosolve, dipropylene glycol methyl ether (DPM), propylene glycol methyl ether (PM), and various others as may provide desired characteristics in blending and application for the particular formulation of interest.

Cosolvents will preferably be present in about 0-30 parts, more preferably 1-20 parts, and most preferably 1-10 parts. Corrosion Inhibitors

The preferred corrosion inhibitors for the purposes of the invention are the most preferred metal passivator commonly known as Cobratec^R TT85 available from PMC Specialities, Cincinnati, Ohio, which is a sodium salt of tolytriazole. Other effective corrosion inhibitors are ammonium salts of dichromate and molybdate and the Corbratec benzotriazoles. SACI 445W emulsion from Witco Chemical and other calcium sulfonate emulsions can be used. Ammonium benzoates and sodium nitrites can also be employed in the formulations in the present invention. It has been found that experimental emulsion 31327X1 from Michelman, Inc., Cincinnati, Ohio, has a particular advantage in the present invention because it has been discovered to not only have both a corrosion inhibition, but also a stabilizing effect when used in the formulations of the present invention.

Corrosion inhibitors will generally be present in about 0.1-15, more preferably 0.1-10, and most preferably 0.5-5 parts by weight based on the weight of the formulation.

Surfactants

Preferred surfactants include non-ionic surfactants, e.g. Triton X-100, a 100% active octyl phenoxy polyethoxy ethanol having a HLB value of 13.5 and available from Rohm & Haas. Other non-ionic surfactants, e.g. Igepal, available from GAF may be used. Anionic and cationic surfactants may be used in specialized circumstances, but are generally not preferred because they have a tendency to attack the underlying paint film which is to be protected and because they may form unstable emulsions due to their incompatibility with other ingredients. Triton X-100 is particularly preferred because it has a two-fold advantage. Triton X-100 imparts excellent surface wetting of the mixture, and also renders the cured film more sensitive to removal by hot water, providing additional ease in removability.

Surfactants will generally be present in amounts of about 0.1-10, more preferably 0.2-5, and most preferably 0.5-2.0 parts by weight based on the total weight of the formulation.

UV Additives

Though not required for the formulations of the present invention, their economics and solubility considerations will permit, various UV absorbers, hindered amine light stabilizers and anti-oxidants may be incorporated to lengthen or improve the desired protection provided to the underlying coating by the temporary films of the present invention. UV absorbers and HALS function to keep the acrylic resin from cross-linking from outdoor heat and UV exposure, and thereby permit longer periods of protection and provide films which remain easy to remove.

When used in the present invention, UV additives will generally be present in amounts of 0.05-5%, more preferably 0.1-2%, most preferably 0.15 to about 1% by weight, but these amounts are not narrowly critical.

Defoamers

In most of the formulations of the present invention, defoamers are valuable additives and any of the common defoamers currently used with water-based acrylic formulations are acceptable. Particularly preferred is BYK 020 available from BYK-Chemie and

SWS211 available from SWS Silicones Corp. in Adrinn, Michigan.

Defoamers will generally be used in very small amounts ranging from a trace to 5.0, more preferably 0.01 to about 2, and most preferably 0.02-0.5 parts by weight based on the weight of the formulation.

Other Additives

Various corrosion inhibitors, wax emulsions, and additives commonly known to those skilled in the coatings art may be added to tailor specific properties desired in cured films according to the invention.

Techniques in Mixing

Apparatus: The apparatus for the present invention will be that conventionally utilized in the preparation of coatings compositions, e.g. kettles and mixing tanks having flow metering or measuring devices and agitation means, e.g. pumps mounted on side-arms connecting with the main vessel, internal stirrers, contra-rotating shearing devices and any of the other available devices which are well known to the art.

Temperature: The entire formulation of the present compositions can be accomplished at or near room temperature without need for expensive heated vessels, temperature control, etc. No substantial exotherm is involved during formulation of the compositions of the invention in most cases. The temperature during mixing may be different during different stages in the formulation. These temperatures are not narrowly critical and will vary to provide faster mixing or better compatibility of ingredients according to observation of those skilled in the art. For example, pressure vessels may be utilized for the purpose of lowering ingredient melting and boiling points, where useful, in order to provide better dispersion of difficult-to-mix ingredients.

Mixing Procedure: While the formulations of the present invention may be manufactured continuously if desired, batch techniques will be more usually employed. Acrylic emulsions, water, corrosion inhibitors and neutralizing agents are mixed in a stainless vessel.

Quality Control:

The finished formulation, prior to packaging, will generally be checked for viscosity, solids content, freeze-thaw stability, film build, spray ability, corrosion-protection under accelerated conditions and other tests utilizing techniques well known to the coatings industry.

Application:

The formulations of the present invention may be applied to substrates to be protected by conventional application techniques, such as spraying, brushing, dipping, flow-coating, electrostatic airless spraying. Coating thickness can be varied by changing the formulation, the number of coats, or the amount applied per coat but in general will be in the range from about 0.5 to about 5 mils after drying. EXAMPLES

Example 1

(Formulations according to the invention providing firm film for protection of underlying permanent paint layers and also providing easy removability with alkaline cleaners)

To a conventional unjacketed mixing kettle equipped with mild impeller rotary mixer or agitation are added, in order: 55.3 parts by weight of Neocryl BT-520, an alkali-soluble acrylic emulsion manufactured by Polyvinyl Chemical Industries and described above under "Acrylic Emulsions" at room temperature (about 20°C); 42.10 parts by weight of water (tap water) at tap temperature (approximately 15°C), these components are allowed to mix until homogenous, no substantial reaction is involved. To this mixture is added very slowly 1.79 parts by weight of aqua ammonia (28° Baume NH40H) which will cause the mixture, previously milky, to become clear. This neutralizes the acid groups on the acrylic resin but involves no substantial exotherm. To this clear mixture is added 0.18 parts by weight of Triton X-100, a nonionic surfactant manufactured by GAF, 0.45 parts by weight of Cobratec-85, a sodium salt of a tolytriazole manufactured by PMC Specialities, and 0.18 parts by weight of BYK-020, a defoamer manufactured by BYK Chemie. Agitation is continued during the addition of all of the ingredients. No heating is required. Agitation is continued for about two hours until the mixture is entirely homogenous.

The homogenous batch is sampled for quality control and the pH is found to be about 9 (a range of pH is preferably from about 8 to 10, more preferably from about 8.5 to 9.5). Nonvolatiles are measured by wt% of evaporation and found to be approximately 23%

(nonvolatiles will generally be in the range of from about 18 to 27, more preferably from about 20 to 25, and most preferably from about 21 to 24% though these can, of course, be reduced by dilution of the formulation, e.g. for specialized applications).

ASTM Method D-2369 is used to determine nonvolatiles.

Viscosity is found to be about 23 seconds using a Ford Number Four cup viscometer (preferred viscosity will be in the range of from about 15 to about 27, more preferably from 18 to about 25, and can also vary with dilution as needed).

Resulting product is tested for weathering resistance by applying it to a cold rolled 10 10 steel panel which has been painted with a Dupont acrylic enamel which is sprayed on. After drying for 24 hours, the test panel is subjected to a xenon light Weatherometer operated according to ASTM G-26-83 and resists over 300 hours of exposure to the Weatherometer without failure.

A panel which had been exposed for 300 hours to the Weatherometer was then sprayed with a cleaner composed of water, DPM (co-solvent) and Triton X-100 (surfactant) and 28° Be aqua ammonia. The temporary coating of the present invention is readily removed with gentle sponging (allow to set for 3-5 minutes). The alkaline cleaner effectively solubilizes the coating and it removes readily. Examination of the underlying acrylic enamel permanent finish shows no visible staining, no apparent gloss reduction or other apparent softening or damage to the permanent film.

The coating composition exhibits good freeze/thaw stability over 5 cycles of 8 hours at 0°F followed by 16 hours at about 25°C and repeat.

Examples 2-13

(Formulations produced according to the techniques of Example 1, but using the respective parameters set forth in Table 2 provide the results described in Table 2)

Example VI is a commercial temporary protective formulation available from Eastman Kodak comprising:

(Eastman E43 Anionic Emulsion)

Eastman E43 Polyethylene 40 PBW

Tall Oil Fatty Acid 7 PBW

Morpholine 6 PBW

KOH 3 PBW

Sodium Metabisulfite 0.4 PBW

Isobutanol 4 PBW

Water 61 PBW

Example VII is a commercial temporary protective coating also available from Eastman comprising:

(Eastman E-10 Anionic Emulsion)

Eastman E10 Polyethlene 40 PBW

Tall Oil Fatty Acid 7 PBW

Morpholine 6 PBW

Water 103 PBW

MODIFICATIONS Specific compositions, methods, or embodiments discussed are intended to be only illustrative of the invention disclosed by this specification. Variation on these compositions, methods, or embodiments are readily apparent to a person of skill in the art based upon the teachings of this specification and are therefore intended to be included as part of the inventions disclosed herein.

For example, pigments or non-staining dyes can be added to provide distinctive color and/or opacity, multiple coats can be used, compositions can be diluted as needed to provide desired film thickness and ease of application. These compositions will typically permit recoating with additional coats of similar compositions without wrinkling or lifting of the base coat. In fact, the second coating will generally cause some softening of the first layer of the temporary coating so that the two coats fuse together and form a desirably thick coat.

Reference to patents and other literature made in the specification is intended to result in such patents or literature being expressly incorporated herein by reference including any patents or other literature cited within such patents.

Claims

1. Anti-corrosive, storage stable, water-based, water or co-solvent reducible, non-staining, dispersible coating compositions removable with water-based alkali cleaners at room temperature, capable of application and flow on solid substrates to form a firm but removable coating, said composition comprising:

A. alkali soluble acrylic emulsion;

B. water-soluble amine or aqueous ammonia;

C. surfactant having a hydrolipo balance (HLB) of from about 10 to about 15; and

D. water with optional co-solvents, corrosion inhibitors, UV additives, defoamers and other additives.

2. A composition according to Claim 1 wherein the surfactant comprises a alkyl phenoxy polyethoxy ethanol or other nonionic surfactant.

3. A composition according to Claim 1 comprising 0 to 30% weight co-solvents selected from the group consisting of alcohols and glycol ethers.

4. A composition according to Claim 1 further including about 0.1 to 15% by weight of corrosion inhibitors.

5. A composition according to Claim 4 in which co-solvents comprise faster evaporating alcohols selected from the group consisting of methanol, ethanol, isobutanol, secondary butanol.

6. A composition according to Claim 5 comprising corrosion inhibitors selected from the group consisting of benzotriazoles, tolytriazoles, ammonium salts of dichromates and molybdates.

7. A composition according to Claim 1 in which the acrylic emulsion is an acrylic copolymer emulsion having acid value in the range of about 20-200.

8. A composition according to Claim 7 comprising the sodium salt of tolytriazoles.

9. A method for coating solid substrates wherein a composition according to Claim 1 is applied to a painted substrate by dipping, brushing, rolling and/or spraying.

10. An article of manufacture comprising a painted substrate coated with a film derived from a composition of Claim 1.