Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-02-09
2003-04-08
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S504000, C523S505000, C523S509000, C523S511000, C523S514000, C523S515000, C523S516000, C523S521000, C523S527000, C524S004000, C524S005000, C524S057000, C524S058000, C524S906000, C156S327000, C156S332000, C156S336000
Reexamination Certificate
active
06545068
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a grouting composition.
BACKGROUND OF THE INVENTION
Anchor bolts are employed in various fields of engineering, for example, as strengthening or reinforcing members in rock formations and in structural bodies. The bolts are inserted into drill holes in the formation or body, and often are fixed or anchored, at their inner end or over substantially their entire length, by means of a reactive grouting composition that hardens around the bolt. When used in a mine roof, bolts grouted in this manner help significantly to prevent mine roof failure.
A grouting composition generally contains a resin and water. Such a water-based composition is typically placed in boltholes using tubular compartmented cartridges and should be held rigid by the internal package pressure. The internal pressure is created by a cartridging machine when end clips are applied to the cartridge film to seal the contents.
However, within about two months, the cartridges become limp or lacking in stiffness or firmness. Such limp cartridges are a problem for the customer because limp cartridges are difficult to insert into overhead boreholes. It was found that most of the limpness was caused by water permeating through the film and not from leakage through the end clips. For example, a Mylar® (terephthalate polyester) film used throughout the industry because of its high modulus has an extremely high permeability to water. Thus, any grouting formulation containing water is subject to limpness due to loss of water volume. Formulations that do not use water are not subject to this problem. However for formulations described in the U.S. Pat. No. 4,280,943, the limpness can be a significant problem.
Solutions that reduce the water loss such as coating the polyester film with Sarane®, metal, or polyethylene work well and have been employed to reduce the water loss. However, such solutions are very expensive typically doubling the packaging cost.
Therefore, there is an increasing need to develop a composition that can retains the firmness or stiffness of the package for a reasonable period time and at reasonable cost. One advantage of the present invention is that, instead of reducing the water loss to retain stiffness, the invention composition keeps the cartridge package stiff as water is lost. Other advantages of the invention will become more apparent as the invention is more fully disclosed hereinbelow.
SUMMARY OF THE INVENTION
According to the invention, a composition that can be used as a grouting composition is provided. The composition comprises, consists essentially of, or consists of a compressible substance, a first component, and a second component. The first component comprises a peroxide, a liquid that comprises water, a solid particulate, and optionally a sugar. The second component comprises a polymer, a crosslinking agent, and a solid particulate. The compressible substance can be present in the first component, the second component, or both.
According to another embodiment of the invention, a process for substantially improving the firmness of a grouting composition is provided. The process comprises introducing a compressible substance into a grouting composition. The grouting composition can comprise the first and second components disclosed above. The compressible substance can be introduced into the first component, the second component, or both.
DETAILED DESCRIPTION OF THE INVENTION
The term “first composition” or “second composition” is interchangeably used in the application as “first component”, or “second component”. The term “compressible substance” refers to a material that, when present in a grouting composition, expands as the water or water vapor in the grouting composition is lost thereby maintaining a rigid package of the composition. The term “substantially” refers to more than trivial. The term “limp” or “limpness” refers to the state that a cartridge containing a grouting composition is not as rigid as the cartridge originally packaged. The two components can be separated by, for example, a floating polyester membrane.
According to the invention the compressible substance can be any compressible substance that expands as the water or water vapor is lost thereby maintaining a rigid package of the grouting composition such that it can be easily inserted in boreholes. Examples of preferred compressible substances include, but are not limited to, nitrogen, oxygen, air, a nonflammable gas, soft rubber, foam rubber, and combinations of two or more thereof. Examples of nonflammable gases include, but are not limited to, Freon® 12, carbon dioxide, argon, or combinations thereof. The compressible substance used in the invention composition is substantially not permeable through the cartridge of the composition or is substantially less permeable than water. Compressible solids such as rubber can also be employed.
The compressible substance must be substantially less permeable than water and low in cost. Nitrogen is an ideal compressible substance because it is over 1000 times less permeable than water through polyester film and is low in cost.
The compressible substance can be present in the first component, second component, or both. Generally, it can be present in about 0.1 to about 40, preferably about 1 to about 20, and most preferably 2 to 10 volume % of the total volume of the composition. The volume of the compressible substance generally is such that it is at least equal to the volume of water that is lost for the desired use period. For example, if 10 cc (cubic centimeter) of water is lost from the package over a 6-month period, the volume of compressible substance is 10 cc. However, generally, it requires at least about 10 cc.
The compressible substance can be combined with the first composition, the second composition, or a composition comprising the first and second composition. The compressible substance can be introduced into the composition by any method known to one skilled in the art such as, for example, whipping in very small bubbles that do not rapidly separate. Preferably the compressible substance such as a gas can be injected at a packaging machine though a small tube or tubes that creates a series of small bubbles over the length of the package in either first compartment, second compartment, or both.
Suitable peroxide can be an organic peroxide, an inorganic peroxide, or combinations thereof. The presently preferred peroxide is an organic peroxide, which can be any diacyl peroxides. Examples of suitable organic peroxides include, but are not limited to, benzoyl peroxide, dichlorobenzoyl peroxide, dibromobenzoyl peroxide, dimethoxy benzoyl peroxide, and combinations of two or more thereof. The presently preferred organic peroxide is benzoyl peroxide because it is readily available and effective for use in a grouting composition.
Any liquid that comprises water can be used in the composition of the first embodiment of the invention. The liquid can also comprise a second liquid such as a freezing point depressing material. The second liquid can be a polyalcohol such as ethylene glycol and propylene glycol, solution of calcium chloride, solution of sodium chloride, and combinations of two or more thereof.
A suitable liquid can also comprise a thickener, which keeps the liquid in diffused or well-mingled form. Examples of suitable thickeners include, but are not limited to, cellulose, methylcellulose, hydroxyethyl cellulose, and combinations of two or more thereof. A thickener can be present in the first component in any quantity that can thicken the liquid, generally in the range of from about 0.1 to about 30 weight %, based on the total weight of the liquid.
According to the invention, the invention can also comprise a sugar. The term “sugar” refers to a carbohydrate selected from the group consisting of monosaccharides, disaccharides, trisaccharides, tetrasaccharides, oligosaccharides, sugar alcohols, derivatives thereof, and combinations of two or more thereof. Generally a suitable oligosaccharide has about 4 to
Barsotti Domenic Joseph
Gramlich Phillip Edwin
Simmons Walter John
E. I. du Pont de Nemours and Company
Szekely Peter
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