FR2543514A1 - Soluble protective film - Google Patents

Abstract

Process making it possible to protect temporarily the surface of a substrate in the course of treatment, manufacture or handling, by applying a protective film of a soluble polymer to the surface. The surface of the substrate is coated with a solution of a soluble film-forming polymer and the solvent is evaporated off to form a film at the surface of the substrate. The polymer is preferably soluble in water and is chosen from the group of alginates, polyvinyl alcohols, polyvinylpyrrolidone and copolymers thereof. The solution may include various conventional additives such as particulate spacing materials, for example polyethylene beads, so as to form an insert layer between adjacent substrate surfaces. Particular application to the protection of stacked glass sheets or plates.

Description

 the present invention relates generally to the technique of protecting glass surfaces from stains and scratches, and more particularly to the technique of protecting glass surfaces, without permanent modification of the glass surfaces, using removable protective films.

 US Pat. No. 3,723,312 (RAY) describes the use of dusted agglomerated salicylic acid with an inert particle separation material, such as sawdust or polystyrene to prevent soiling of the stacked glass sheets. U.S. Patent No. 3,798,112 (HAY) describes the agglomeration of salicylic acid with polyethylene oxide to produce an interlayer material which further comprises an inert particle separation material, such as sawdust or polystyrene , to prevent soiling of stacked glass sheets.

US Patent No. A 011,359 (SISiPKIN et al.) Describes an interlayer material for separating glass sheets and protecting them from stains and scratches, which contains a finely divided porous support material, impregnated with a weakly acidic material, and fine particles of chemically inert plastic
US Patent No. 4,200,670 (ALBACH) describes a process for protecting glass sheets during their packaging, transport and storage. The process consists in applying water, a dirt-inhibiting material, and finely dry particles. divided by a mechanical separator on the surfaces of the glass sheets before stacking them, according to several encircled steps which produce an adherent coating which acts as a protective interlayer between the glass surfaces facing each other when the sheets or plates are stacked.

 US Patent No. 4,263,371 (FRANZ) describes a process for reducing the surface energy of a glass article by chemisorption of an alkyltin compound. The functional tin part binds to the surface of the glass, while the organic part is oriented outwards from the glass by forming a low energy surface layer which gives low friction, low chemical reactivity and repels water. , dirt and glass shavings.

 US Patent No. 4,276,350 (FRANZ) describes a process for reducing the reactivity of a glass surface using a fluorinated hydrocarbon. The process involves adsorbing multivalent metal cations on the surface of the glass to form anchor sites for the chemisorption of otherwise non-reactive fluorinated hydrocarbons. your glass surface treated with a resulting fluorinated hydrocarbon repels water as well as organic solids.

 US Patent No. 4,360,544 (FR NE) describes a process for protecting the surfaces of stacked glass sheets by chemisorption of an organotin compound on the glass surfaces, and the separation of the glass surfaces adjacent to using an inert interlayer material.

 The previous references to the FRANZ patents describe the protection of a glass surface using a treatment which causes reaction and incorporation on the glass surface. In some cases, a removable protective layer is sought. For example, when the glass sheets and plastic interleaves are laminated in an oil autoclave for the production of safety windshields, the removal of the oily residue from the glass surfaces often requires several costly cleaning steps using washes. Detergents and hot water rinses, as well as high speed blowing drying. According to the present invention, a water-soluble but oil-insoluble protective film is applied to the exposed glass surfaces. before stratification in the oil autoclave. Thereafter, the oily residue as well as the protective film can be removed by a single rinse with hot water.

 A water-soluble polymeric protective film according to the present invention can be advantageously used in a wide variety of applications. When applied to a clean glass surface prior to manufacturing processes, a water-soluble polymeric protective film according to the present invention minimizes handling marks, such as fingerprints and marks from rollers or belts, - as well as the adhesion of dust and debris, After manufacture, handling and installation of the protective film is easily removed by washing, leaving a clean and unmarked glass surface.

 A temporary protective film is applied to a substrate surface by application of a solution of a film-forming polymer which is soluble on the surface and evaporation of the solvent. your film protects the surface from dust, debris, fingerprints, roller marking, belt marks, etc., during manufacturing, handling and installation Subsequently, the soluble protective film is easily washed away leaving a clean unmarked surface. your protective protective film of the present invention is particularly usable on glass sheets or plates.

 The present invention also provides an interlayer material for protecting and separating adjacent surfaces, as well as effective temporary surface protection; The present invention consists of S-formx a soluble polymer film on the surface of the substrate. The soluble polymer film may also comprise inert insoluble spacing particles such as polyethylene or acrylic beads, as well as dirt inhibitors - such as adipic acid, or hydrophobic additives such as colloidal silica which have undergone a chemical reaction. The protective film of the present invention is applied to a surface of substrate before handling, storage, transport, installation, etc., to protect the surface from stains, scratches, dirt , fingerprints, etc. When the substrate has reached its final destination, the soluble protective film is easily removed by ordinary washing operations.

A thin protective film of a soluble polymer is preferably applied to a substrate by bringing the surface of the substrate into contact with a solution of the polymer and evaporating the solvent. We can latinize any convenient application techniques, such as brushing, soaking or spraying. Preferred solvents include water as well as volatile water-miscible alcohols and ketones, such as methanol, ethanol, propanol, acetone, methyl ethyl ketone, etc., for rapid drying. also contain a wetting agent improving the uniformity of the film, as well as to improve rinsing and drying without staining, especially when the solvent is water. your preferred polymers are water soluble. A preferred water-soluble polymer is polyvinylpyrrolidone. In some applications, a water-soluble polymer is preferably also insoluble in oil. In such applications, the preferred polymers include alginates and xanthan gums as well as polyvinylpyrrolidone. Copolymers of polyvinylpyrrolidone and polyvinyl dl-acetate can also be used, as well as polymers and copolymers of polyvinyl alcohol.
In a preferred variant of the present invention, a polyvinylpyrrolidone film. - is applied to exposed glass surfaces with sets of glass% sheets / plastic sheets-d laminate in an oil autoclave. The film is preferably applied to the exposed glass surfaces by dipping or spraying, using an aqueous solution of about 1 to 10% polyvinylpyrrolidone. The polyvinylpyrrolidone film withstands the temperature and temperature conditions of the oil autoclave without decomposing and integrating with the glass surface, and there is no reaction or contamination with the oil of the autoclave. After stratification in the oil autoclave, the treated glass surfaces are rinsed with hot water, which removes all oily residues with the protective film of polyvinylpyrrolidone, eliminating the need for several stages of washing with detergent and rinsing with hot water.

 In other preferred embodiments of the present invention, clean glass plates are contacted with solutions of polyvinylpyrrolidone in an alcohol, which may contain a wetting agent for uniform wetting and rapid drying. The solvent is evaporated, and a thin protective film of polyvinylpyrrolidone is formed on the glass surface. The treated glass sheets are then subjected to various manufacturing processes such as machining, drilling, edge-to-edge welding, etc. The polyvinylpyrrolidone protective film minimizes the adhesion of dust and debris, as well as fingerprints, roller marks and belts.

After manufacturing, handling and installation, the glass is simply washed to remove the polyvinyl pyrrolidone film and leave a clean and unmarked glass surface. This surface protection treatment can also be used with various plastic substrates, as well as with polymeric materials such as butyl rubber. Solutions containing up to about 30% polymer are preferred.

 In other preferred embodiments of the present invention the substrates, preferably glass sheets, receive temporary protection against soiling and scratches by application of a protective film of a soluble polymer. Preferably, the glass sheets are contacted with a solution of a water-soluble film-forming polymer, and the solvent is evaporated to form a water-soluble film on a glass surface before the glass is subjected to manufacturing, finishing, handling; stacking, storage, transport, installation. A proffered polymer is polyvinylpyrrolidoney and preferred solvents include water and water-miscible alcohols and ketones such as methanol, ethanol, propanol, acetone and methyl ethyl ketone. Appropriate application techniques include spraying, soaking and roller coating. The polymeric film preferably comprises inert insoluble polymer-organic particles of micron size which act as spacers when the glass surfaces are brought into contact, for example when stacked for storage or transport Preferred polymeric spacers include polyethylene beads or acrylic beads.

 In a preferred embodiment of the present invention, the glass sheets are contacted with a solution of a water-soluble film-forming polymer containing inert insoluble polyethylene particles and hydrophobic colloidal silica. your particles act as spacers when the glass sheets are stacked for storage and transport. When sheets or sheets of glass are used in architectural applications, hydrophobic colloidal silica minimizes wetting of glass surfaces and thus protects these surfaces from soiling usually caused by concrete or mortar as well as other factors of soiling. generally encountered on construction sites.

 In another preferred embodiment of the present invention, when the glass sheets are intended for screen printing or a similar process, a protective film is applied according to the present invention before such treatment. In this embodiment, the protective film is applied to one of the surfaces of the glass plates, and must not be transferred to the opposite surface. In addition, it is preferred that the film-forming polymer, as well as the particulate spacing agent, shine without residue during an annealing cycle. A preferred protective film in this embodiment of the present invention comprises a polyvinylpyrrolidone film and polyethylene particles.

 In another preferred embodiment of the present invention where a protective film of water-soluble polymer essentially acts as an interlayer material, the polymer film preferably contains, in addition to the particulate spacer material, a soil-inhibiting material such as an organic acid.

A particularly preferred protective film contains polyvinylpyrrolidone as a film-forming agent, polyethylene as a spacer and adipic acid as a soil-blocking agent.

The present invention will be better understood from the description of specific examples which follow
Example 1
-Glass sheets are assembled with polymeric spacers so as to form a multilayer unit for stratification. These glass / plastic assemblies are immersed for one minute in an aqueous solution containing 1% of colloidal sodium alginate polymer. The polymer is hydrophilic, insoluble in oils, non-toxic, relatively inexpensive, and readily available from
KELCO CO. under the name KELGIN XL. The glass sheets are removed from the solution and air dried. The treated glass plates are subjected to the conditions of the oil autoclave which are approximately 15 ° C. (3000 ° F) under a pressure of 13.8 bars for 45 min. For comparison, untreated glass sheets are laminated under the same conditions. After removal from the oil autoclave, the treated and untreated laminates are washed to remove oily residue. The treated glass surfaces are free of oily residues after a single rinse with hot water, while the untreated glass surfaces also require washing with hot water and a detergent and at least two additional rinses with water. 'Hot water.

Example -2
Glass / plastic assemblies as described in Example 1 are immersed in an aqueous solution containing 2% of polyvinylpyrrolidone and 0.1% of a wetting agent, available under the name ZONrL FSN from Dupent de Nemours.

The assemblies are removed from the solution, air dried and subjected to stratification conditions in the oil autoclave, as well as untreated glass / plastic assemblies, as in the previous example. After removal of the other clave, all glass surfaces are washed to remove oily residue. As in the previous example, the treated glass surfaces are free of oily residues after a single rinse with hot water, while the untreated glass surfaces require washing with hot water and detergent and at least two additional hot water rinses.

Example III
An aqueous solution of 2% polyvinylpyrrolidone and 0.05% of wetting agent is sprayed on glass / plastic assemblies as in Example 2. The treated assemblies, as well as untreated control assemblies, are subjected to the conditions of the oil autoclave as in the previous examples. Again, only the treated glass surfaces are free of oily residue after a single rinse with hot water.

Example IV
A solution of 10% of polyvinylpyrrolidone and 0.1% of wetting agent in isopropanol is sprayed onto glass sheets, which evaporates rapidly. The sheets, as well as untreated glass sheets, are subjected to edge polishing, which generates abrasive particles as well as siliceous debris particles which contaminate the glass surfaces. After this treatment, the treated and untreated sheets of glass are subjected to a single rinse with hot water. The treated glass sheets come out clean while the untreated sheets remain streaked and stained, and require manual cleaning with a glass cleaner to remove siliceous debris.

Example V
Pairs of glass sheets are transformed into sets of multi-pane windows with edges surrounded by butyl rubber. Butyl rubber can become sticky and adhere to packaging materials, or debris can adhere to the surrounded edges. To eliminate the problems associated with the sticky state of butyl rubber, the edges surrounded by the units are brought into contact, before handling and transport, with a solution containing 20 to 30% of polyvinylpyrrolidone in water or isopropanol. The solution is applied with a brush and the solvent is evaporated, leaving behind a thin transparent film of polyvinylpyrrolidone which is not sticky.

The units are heated to around 1200C (2500F) for 20 mins and there are still no sticky spots on the surface.

These units are transported, stored and installed without any adhesion of impurities being encountered on the surrounding butyl rubber. The protective film is removed when desired by washing with water.

Example VI
A solution is prepared containing 2% of polyvinylpyrrolidone and 2% of interlayer material in propanol. The interlayer material is an equal weight mixture of acrylic beads and adipic acid. This composition is sprayed onto the surfaces of glass sheets coated with a metal oxide. After two weeks of exposure to 600C and a relative humidity of 90%, the treated glass surfaces show no foam or stains. By comparison, adjacent glass surfaces separated by newspaper have a slight froth, and adjacent surfaces separated by other conventional interlayer materials have an even greater deterioration of the surfaces.

Example VII
A solution is prepared containing 2% of polyvinyl pyrrolidonep 2 2 of polyethylenep particles 2% of hydrophobic colloidal silica and 0.2 W of a wetting agent (ZONYL-FSN from DuPont de Nemours) in isopropanol The composition is sprayed on surfaces of metal oxide coated glass sheets to protect them from concrete and mortar dust on construction sites.

To test the protection provided by the soluble film, the treated leaves are placed in a horizontal position and they are brought into contact with a cement slurry which is left to dry on the coated glass surface. The leaves are then placed in a humid chamber. 500C and 100% relative humidity for two weeks. When the samples are removed from the chamber and washed, the cement is washed away and the coated glass surface is clean with no stains.

Example VIII
To protect glass surfaces from dirt and scratches before screen printing and tempering, it is necessary to use on a glass surface a protective film which does not undergo transfer to an adjacent glass surface, does not interfere with the process screen printing and is eliminated by combustion without residue during the tempering cycle. A suitable protective film is deposited on the glass surfaces using a solution of 2 g of polyvinylpyrrolidone, 2% of polyethylene particles and 0.2% of wetting agent (ZOWYL-SN from DuPont de Nemours)
This composition is sprayed onto a surface of a number of glass sheets. The protective film formed prevents the glass from being soiled and scratched, does not undergo transfer to adjacent glass surfaces, can be handled with equipment under empty, does not interfere with screen printing and is eliminated by combustion without residue in the tempering cycle.

 The preceding examples are given to illustrate the present invention which may give rise to various modifications. For example, other soluble polymers can be used, such as polyvinyl alcohols or polyvinylpyrrolidone copolymers. Other solvents can be used, preferably water or water-miscible ketones and alcohols such as acetones, methyl ethyl ketone, methanol or ethanol. Other inert spacing materials can be used such as acrylic beads or sawdust. Other possible wetting agents can be used as well as other hydrophobic additives.

 Soluble film-forming polymers can be applied by other techniques such as roller coating, and substrates other than glass, such as plastics, can be protected. The field of the present invention is only defined by the appended claims.

Claims (30)

- CLAIMS  1. Method for obtaining temporary protection of a surface of a. substrate, characterized in. what it includes the steps of bringing the surface of the substrate into contact with a solution of a polymer. soluble film former, and evaporating the solvent to form a soluble polymer film on the surface of the substrate.  2. Method according to claim l, characterized in that the polymer is soluble in water.  3. Method according to claim 2, characterized in that the polymer is chosen from the group comprising alginates, polyvinyl alcohols, polyvinylpyrrolidone and their- copolymers.  4. Method according to. claim 3, characterized in that the polymer is polyvinylpyrrolidone.  5. Method according to claim 3, characterized in that the solution comprises a solvent chosen from the group comprising water, ketones and water-miscible alcohols, and their mixtures.  6. Method according to claim 5, characterized in that the solution further comprises a wetting agent.  7. An article of manufacture comprising a substrate chosen from the group of glass and polymeric materials, and a protective film of a soluble polymer placed on a portion of the surface of said substrate.  8. Article according to claim 7, characterized in that said polymer is soluble in water.  9. Article according to claim 8, characterized in that said polymer is chosen from the group comprising alginates, polyvinyl alcohols, polyvinylpyrrolidone and their copolymers.  10. Article according to claim 9, characterized in that the substrate is glass and the polymer is poly vinylpyrro lidone.  11. Method for obtaining temporary protection on a substrate surface, characterized in that it consists in coating said surface with a film comprising a soluble film-forming polymer and inert insoluble spacing particles.  12. Method according to claim 11, characterized in that the substrate is glass.  13. Method according to claim 12, characterized in that the polymer is soluble in water  14. Method according to claim 13, characterized in that the polymer is chosen from the group comprising polyvinylpyrrolidone, polyvinyl alcohol and their copolymers.  15. The method of claim 14, characterized in that the coating is obtained by bringing the substrate surface into contact with a solution of the water-soluble polymer containing the inert insoluble spacing particles and by evaporating the solvent.  16. Method according to claim 15, characterized in that the solvent is chosen from the group comprising 'water and water-miscible alcohols and ketones.  17. The method of claim 16, characterized in that the polymer is polyvinylpyrrolidone.  18. The method of claim 17, characterized in that the solvent is isopropanol.  19. The method of claim 18, characterized in that the solution further comprises a wetting agent.  20. The method of claim 19, characterized in that the inert spacing particles are a material selected from the group comprising polyethylene beads and acrylic beads  21. The method of claim 20, characterized in that the film further comprises a hydrophobic additive.  22. Method according to claim 21, characterized in that the hydrophobic additive is hydrophobic colloidal silica.  23. Manufactured article comprising a substrate chosen from the group of glass and polymeric materials, and a protective coating placed on a part of the surface of said substrate and comprising a film of soluble polymer and insoluble inert spacing particles.  24. Article according to claim 23, characterized in that the substrate is glass.  25, Article according to claim 24, characterized in that the polymer film is soluble in water.  26. Article according to claim 25, characterized in that said polymer is chosen from the group comprising polyvinylpyrrolidone, polyvinyl alcohols and their copolymers.  27. Article according to claim 26, characterized in that the polymer is polysinylpyrrolidone.  28. Article according to claim 27, characterized in that the inert spacing particles are chosen from the group comprising polyethylene beads and acrylic beads.  29. Article according to claim 28, characterized in that the coating further comprises a soil-inhibiting agent which is an organic acid.  30. Article according to claim 28, characterized in that the coating further comprises a hydrophobic compound.