US3639310A

US3639310A - Wax-resin-hydroxypropyl cellulose thermofluid vehicles

Info

Publication number: US3639310A
Application number: US11845A
Authority: US
Inventors: Ray Andrews
Original assignee: Hercules LLC
Current assignee: Hercules LLC
Priority date: 1970-02-16
Filing date: 1970-02-16
Publication date: 1972-02-01
Anticipated expiration: 1989-02-01

Abstract

THERMOFLUID VEHICLES OF THE WAX-RESIN TYPE FOR VITREOUS ENAMEL COLOR COMPOSITIONS ARE DESCRIBED. THE VEHICLES CONTAIN A FATTY ALCOHOL OF FATTY AMIDE WAX, A RESIN BINDER AND A SMALL AMOUNT OF HYDROXYPROPYL CELLULOSE AND GIVE, WITH ENAMEL COLORS, COMPOSITIONS WHICH DO NOT RUN OR SAG DURING FIRING AND WHICH PRODUCE ENAMEL COATINGS FREE OF STENCIL MARKINGS.

Description

United States Patent 3,639,310 WAX-RESIN-HYDROXYPROPYL CELLULOSE THERMOFLUID VEHICLES Ray Andrews, Washington, Pa., assignor to Hercules Incorporated, Wilmington, Del.

No Drawing. Filed Feb. 16, 1970, Ser. No. 11,845 Int. Cl. C03c J/OO U.S. Cl. 260-17 R 2 Claims ABSTRACT OF THE DISCLOSURE Thermofluid vehicles of the wax-resin type for vitreous enamel color compositions are described. The vehicles contain a fatty alcohol or fatty amide wax, a resin binder and a small amount of hydroxypropyl cellulose and give, with enamel colors, compositions which do not run or sag during firing and which produce enamel coatings free of stencil markings.

This invention relates to vehicles for vitreous enamel color compositions and more particularly to improved thermofluid vehicles of the wax-resin type.

Thermofluid wax-containing vehicles for enamel coating compositions to be applied to base objects by slik or metal screen stencil processes are known. The major problem encountered in the use of these vehicles is run off or sagging from the coated area during firing, and the retention of screen markings on the fired enamel coated object.

Various materials such as the anionic surface active agent which is the reaction product of phosphoryl chloride and a fatty alcohol, ethyl cellulose, azelaic acid and the like have been suggested as additives to wax-containing vehicles for enamel coating compositions to improve stiffness or viscosity at firing temperatures and to prevent running and screen markings. Although such additives improve the performance of the coatings under normal firing conditions, running and sagging still occur under the conditions required for decorating glassware and particularly sham bottom tumblers which have thin sidewalls and heavy bottoms. Additionally, stencil markings are not smoothed out or eliminated so that irregularities persist on the coated surfaces. Moreover, the enamel coatings do not overprint themselves well and different vehicles are required for each coolr coating to obtain commercially acceptable multi-color or multi-tone effects. Overprinting is a particularly desirable property when mat colors and/ or gold effects are required.

It is an object of this invention to provide thermofluid wax-containing vehicles for use ,with vitreous enamel color compositions which, when applied to glassware, will not run or sag during firing and which will produce enamel coatings free of stencil markings. Another object of this invention is to provide a thermofluid vehicle which can be used in multi-color decoration and will over-print itself well.

Now, in accordance with this invention it has been found that the above objects can be realized by vitreous enamel color vehicles comprising by weight (a) 50 to 80% of a normally solid wax-like material selected from the group consisting of straight chain alcohols having 16 to 20 carbon atoms, amides of aliphatic hydrocarbons containing 16 to 20 carbon atoms and mixtures thereof; (b) 8 to 38% of a resinous binder soluble in said wax-like material; and (c) l to 12% of hydroxypropyl cellulose having an MS. of at least 2.

By the expression normally solid wax-like material is meant a material having the characteristics of wax and non-tacky solidity at room temperature (25 C.) but ready fusibility at above about 50 C. The wax-like materials which are suitable as vehicle constituents in accordance with this invention are, as stated, the substantially straight chain alcohols having 16 to 20 ,carbon atoms such as 3,639,310 Patented Feb. 1, 1972 stearyl alcohol, cetyl alcohol and mixtures of such alcohols; the amides of aliphatic hydrocarbons containing 16 to 20 carbon atoms such as the amides of hexadecane, octadecane, octadecane and mixtures thereof; and mixtures of any of the above alcohols and amides. The wax-like material constitutes the bulk of the vehicle and is present within the range of 50 to 80% and preferably from about 60 to about by weight of the vehicle.

The vehicle also contains, as stated above, from 1 to 12% and preferably from 2 to 10% by weight of hydroxypropyl cellulose having an MS. (molar substitution) of at least 2. Such hydroxypropyl celluloses are described in U.S. Pat. 3,278,521 to Klug and are normally solids which are soluble in cold water, insoluble in hot water, and soluble in polar organic solvents. The preferred hydroxypropyl celluloses will generally have an MS. of 2 to 10 and preferably in the range of from about 3 to about 5. They are commercially available in finely divided condition under the Klucel trademark in different viscosity grades. While any of these viscosity grades can be used in the practice of the invention, the lower viscosity grades such as grades I, L and E are preferred. Best results are obtained with Klucel E having an MS. of 2.8 to 4.0 and preferably 3.0 to 3.7 and a viscosity of 200 to 300 centipoises measured at 25 C. on a 10% aqueous solution.

In addition to the wax component and the hydroxypropyl cellulose, the vehicle also contains from 8 to 38% and preferably from 10 to 30% of a resinous binder which is soluble in the wax. The binder can be one or more of the conventional resinous additives known to modify or improve the hardness, toughness, viscosity, bonding properties, pigment and glass Wettability, etc. of thermofluid vehicles. For example the binder will usually comprise about 33% of one or more thermoplastic materials which provide a wetting action for pigment and glass, about 33% of one or more thermoplastic materials which contribute coherence and toughness and about 33% of one or more thermoplastic materials which maintain the viscosity Within a desired range. Useful materials which can be used as the binder component include thermoplastic resins such as rosin; a modified rosin such as hydrogenated rosin and disproportionated rosin; a rosin derivative such as a rosin ester; polymers of the resin acids or rosin; synthetic rubbers; alkyd resins; acrylate and methacrylate resins such as n-butyl methacrylate; the resinous chlorinated diphenyls; styrene resins; ethyl cellulose; and mixtures thereof. Other polymeric materials which are more Waxlike than resinous can also be present for special effects such as dispersibiilty, plasticization, lubricity, etc. Particularly preferred materials of this type are the polyalkylene ether glycols such as the polymethylene ether glycols and the polyethylene ether glycols having an average molecular weight of at least about 4000 and preferably from about 4000 to 6000. Best results are obtained when the vehicle contains in addition to the wax component and the hydroxypropyl cellulose as binder, 3 to 12% of rosin, modified rosin or a rosin ester, 3 to 12% of styrene resin, 2 to 12% of an acrylate resin, 0.5 5to 5% of ethyl cellulose and 0 to 8% of a polyalkylene ether glycol, the total of the above ingredients not exceeding 38% of the vehicle.

The thermofluid vehicle of the invention can be employed in various amounts with respect to the ceramic or enamel color-constituents of the enamel coating compositions. Generally, the proportion of vehicle to enamel color will be between 1:2 and 1:5.

The ceramic or enamel color constituents of the enamel coating are any of the vitrifiable compositions customarily employed in ceramic glaze applications, and generally consist of about 5 to 20% of inorganic oxide pigments and from about 95 to of finely-divided lead borosilicate glass frit.

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The enamel color constituents and vehicle can be compounded in any convenient manner and the resulting enamel color composition applied to an object to be decorated conventionally, as through a screen stencil by means of a squeegee process at a temperature above the melting point of the vehicle. The coated object is then fired at a temperature which will fuse the enamel color and thereby produce a firmly bonded design on the object. The firing temperature will usually range from about 550 to 650 C. If desired, a plurality of color compositions in any desired registry can be superimposed upon each other before carrying out the firing operation.

The invention is further illustrated by the following examples. All parts and percentages are by weight unless otherwise indicated.

EXAMPLE 1 A resin-wax vehicle is prepared by stirring at 165 C. until homogeneous the following ingredients:

n-Butyl methacrylate resin 8 Polystyrene (low molecular weight, soft, plasticizing resin having a Ball and Ring melting point of 75 C. Hydrogenated rosin (softening point of 75 C.) Ethyl cellulose 1 Hydroxypropyl cellulose (M.S. of 3.0-3.7, viscosity of 200-300 cps. at 25 C. as measured on a 10% by weight aqueous solution) 6 1 Ethoxyl content of 47.5 to 49.0%, a degree of substitution of 2.42-2.53 and a viscosity of 200 cps. at 25 C. measured on a. 5% by weight solution in 80 20 toluene: ethanol by weight on sample dried 30 minutes at 100 C. The above vehicle is mixed with 500 parts of a glass color comprising 85% of a lead borosilicate glass flux and of titanium dioxide pigment (both being of a particle size substantially finer than the decorating screen through which they will pass) at 100 C., applied as a decorative coating on sham bottom glass tumblers by metal screen printing and then fired at 600 C. for 15 minutes. The coating is free of irregularities and screen marks and no running or sagging is encountered during firing.

When a vehicle is prepared in the same manner except that no hydroxypropyl cellulose is present and the amount of ethyl cellulose is increased to 7 parts, the decorated glassware is inferior, running and sagging having occurred during firing and screen marks being present on the surface of the coating.

EXAMPLE 2 The procedure of Example 1 is repeated except that the vehicle additionally contains 5 parts of a polyethylene 4 ether glycol having a molecular weight of about 4000, and 5 parts of n-butyl methacrylate resin, 4 parts of polystyrene and 4 parts of hydrogenated rosin are used. Excellent coatings which do not run or sag on firing and are free of stencil marks are produced.

EXAMPLE 3 The general procedure of Example 1 is repeated except that a multi-color decoration is applied to the glass tumblers prior to firing by overprinting different color compositions prepared with the vehicle of Example 1. In overprinting, each successive print decoration is superimposed, at least in part, over a prior print decoration. Excellent final decorations of multi-color design result with no running of color or sagging and no screen marks when 2, 3, 5 and 8 layers of decoration are employed.

What I claim and desire to protect by Letters Patent is: 1. A thermofluid vehicle for vitreous enamel color compositions comprising by weight (a) 50 to of a normally solid wax-like material selected from the group consisting of straight chain alcohols having 16 to 20 carbon atoms, amides of aliphatic hydrocarbons containing 16 to 20 carbon atoms and mixtures thereof; (b) a resinous binder soluble in said wax-like material and comprising 3 to 12% of rosin, modified rosin or a rosin derivative, 3 to 12% of a styrene resin, 2 to 12% of an acrylate resin, 0.5 to 5% of ethyl cellulose and 0 to 8% of a polyalkylene glycol ether, the sum thereof not exceeding 38% by weight of the vehicle; and 1 (c) 1 to 12% of hydroxypropyl cellulose having a molar substitution of at least 2.

2. The vehicle of claim 1 wherein the modified rosin is hydrogenated rosin.

References Cited UNITED STATES PATENTS 2,379,507 7/ 1945 Deyrup 260-16 2,607,701 8/1952 Jessen 106-123 2,617,704 11/1952 Morris 106-311 2,823,138 2/1958 Hoflman 106311 3,084,129 4/1963 Hoffman 26017 R 3,089,782 5/1963 Bush et a1 1l7-38 3,414,417 12/ 1968 Miller et al 10626 WILLIAM H. SHORT, Primary Examiner L. M. PHYNES, Assistant Examiner US. Cl. X.R. 106-26, 173; 26027, 28.5