Mold release composition

Details Mold release composition Mold release composition

2002-02-08

2003-09-16

Marcheschi, Michael (Department: 1755)

Compositions: coating or plastic

Coating or plastic compositions

Molds and mold coating compositions

C106S038200, C106S038240, C106S038700, C264S333000, C264S338000, C264S213000

Reexamination Certificate

active

06620230

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a mold release composition for the molding of hydraulic bonding materials, for example, concrete.
BACKGROUND OF THE INVENTION
Concrete release agents are applied to the molds, forms or other surfaces that come in contact with freshly mixed concrete. The majority of concrete release agents contain hydrocarbon solvents, and/or oils that are known to cause health and fire hazard related problems. For example, compositions currently used are known to cause dermatological problems when contacting the skin of certain people. These compositions also threaten groundwater supplies due to spillage, runoff and overspray. Because spraying is a common method of applying concrete release agents, prolonged breathing of their aerosolized mists can cause respiratory problems. Many of these compositions also have a disagreeable odor. Additionally, these materials are known to create contamination when scrap concrete parts containing transferred mold release material are put in landfills. Attempts to overcome one or more of these disadvantages have included using vegetable oil-based and water-based mold release compositions, but the result has been a lowering of the releasability and effectiveness of the mold release composition.
There is thus a need for an effective mold release composition that is environmentally friendly and less hazardous to persons working with the composition.
SUMMARY OF THE INVENTION
The present invention provides a mold release composition for facilitating demolding of hydraulic bonding materials, such as concrete, from molds or other tool surfaces by application of an effective amount of the mold release composition to the mold surfaces. To this end, a mold release composition is provided comprising at least one low vapor pressure hydrocarbon fluid or a blend of low vapor pressure hydrocarbon fluids. In an exemplary embodiment of the present invention, this hydrocarbon fluid is used in combination with a release modifying material. The hydrocarbon fluids in the compositions of the present invention are low vapor pressure fluids having a vapor pressure less than about 0.1 mm Hg at 20° C., making the compositions nonhazardous, nonflammable and environmentally friendly, including at least moderate biodegradability. The low vapor pressure hydrocarbon fluid alone exhibits release characteristics for the bonding materials. However, release ease may be improved or augmented by combining the hydrocarbon with a release modifying material, such as an acid bearing material. In the method for using the composition of the present invention, the composition is applied to the molding tool surface prior to molding the article, then following molding and curing of the article, the article is released from the tool surface.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides biodegradable release compositions for facilitating the demolding of hydraulic bonding materials, such as concrete, from molds or other surfaces by application of an effective amount of the release composition to the surface, wherein the release composition includes at least one low vapor pressure hydrocarbon fluid. The low vapor pressure hydrocarbon fluid provides superior release and environmental benefits. The hydrocarbon fluid may be combined with a release modifying material, including but not limited to acid bearing materials, such as fatty acids. The raw materials utilized in the composition of the present invention have multiple FDA and EPA approval ratings, even some with direct food contact applications. The mold release composition has a high flash point rating, for example above about 195° F. (90.5° C.), and a low vapor pressure, generally below about 0.1 mm Hg at 20° C., making the composition safer to use not only from the standpoint of fire hazard, but also from the standpoint of worker safety because workers will not have to breathe volatile and often harmful volatilized hydrocarbon fractions. Scrap parts containing transferred release composition of the present invention may be landfilled under stringent regulations due to the moderate to high biodegradability of the raw materials utilized in the composition. The mold release compositions of the present invention are less hazardous to the skin, eye, nose and throat of individuals coming in contact either on a spot or continuing basis.
The mold release compositions of the present invention may also be applied at lower weights to the molds or other substrates, therefore representing not only a cost savings for the customer, but also less release weight percent on the molded concrete article. By way of example, current mold release compositions normally require about 50-90 grams per square meter of tool surface, whereas compositions of the present invention are effective with less than about 50 grams per square meter or less, for example about 20-50 grams per square meter. In addition, the mold release composition exhibits markedly improved “release ease” versus products currently in use in production settings. The molded products release very easily from the tool surface, with little to no-mold buildup. Scrap rates due to part breakage are also significantly reduced.
The main ingredient in mold release compositions of the present invention is a low vapor pressure hydrocarbon fluid, wherein low vapor pressure is understood to refer to a vapor pressure on the order of less than 0.1 mm Hg at 20° C. This low vapor pressure hydrocarbon fluid is biodegradable, resulting in improved degradation characteristics of the product in landfill applications, i.e. when scrap molded articles are discarded. Use of the low vapor pressure hydrocarbon fluids lessens hazards normally associated with conventional mold release systems, such as high volatility, which exposes the worker to inhalation hazards. Moreover, the hydrocarbon fluid of the present invention is typically non-flammable, thereby lessening the hazards associated with conventional flammable mold release systems.
In one example of the present invention, the low vapor pressure hydrocarbon fluid comprises an isoparaffinic hydrocarbon fluid or is a blend of isoparaffinic hydrocarbon fluids, such as a predominantly C12-C20 isoparaffinic hydrocarbon fluid, which refers to a fluid having as a majority component an isoparaffinic hydrocarbon with 12-20 carbons. Examples of such materials include hydrotreated middle petroleum distillates available from Exxon Mobil Corp. under the names Isopar® V and Isopar® M. Isopar® V is classified with CAS No. 64742-46-7, which covers the process for manufacturing hydrotreated middle petroleum distillates. Isopar® V is essentially a branched alkane of relatively low vapor pressure consisting predominantly of C12-C20 isoparaffinic hydrocarbons. It has a minimum flash point of about 244° F. (118° C.), and typically about 262° F. (127.7° C.). The “minimum flash point” corresponds to the flash point when all the molecular fractions of the hydrocarbon fluid are at the low end, whereas the “typical flash point” is the flash point most commonly exhibited by the fluid. Isopar® M is essentially a lower boiling version (i.e. lower molecular weight) of the Isopar® V, and it has a minimum flash point of about 177° F. (80.5° C.), and typically about 199° F. (93° C.). Both of these hydrocarbon fluids further comprise some cycloparaffins and less than 0.1% aromatics. Lower boiling distillates, such as Exxsol® D110, Exxsol® D95, Exxate® 1000, Exxate® 1200 and Exxate® 1300, each from Exxon Mobil Corp., may also be used, alone or in combination, for the low vapor pressure hydrocarbon fluid of the present invention. The Exxsol® fluids are mixed hydrocarbons, specifically, a mixture of normal, cyclo and isoparaffins, and have minimum flash points of about 221° F. (105° C.) and 200° F. (93° C.), respectively, and .typically about 244° F. (117.7° C.) and 205° F. (96.1° C.), respectively. The Exxate® fluids are mono-esters, specifically, a mixture of iso-alkyl acetates, and have typical flash points of 212° F. (100° C.), 225° F. (107° C.)

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