US2753992A - Packaging methods and products - Google Patents

Description

July 0, 1956 s. MANCHESTER 4 2,753,992

PACKAGING METHODS AND PRODUCTS Filed Sept. 24, 1953 INVENTOR RANDALL S. MANCHESTER.

BY W

ATTORNEY United States Patent 2,753,992 PACKAGING METHODS AND PRODUCTS Randall Stuart Manchester, Troy, N. Y., assignor, by mesne assignments, to Norton Company, Worcester, Mass., a corporation of Massachusetts Application September 24, 1953, Serial No. 382,120 8 Claims. (Cl. 206-59) This invention relates to packaging methods and products. Specifically, it is concerned with methods for forming packages of coated abrasives and to moistureprotected packages of coated abrasives.

Most coated abrasives, popularly called sand-paper, have a pronounced tendency to pick up moisture when stored in high-humidity atmospheres and to lose moisture when held in dry atmospheres. This is due to the hydrophilic qualities of the backing sheets from which the abrasives are made, the adhesive layers of the abrasives, or both.

Many attempts have been made to solve this problem of moisture change in coated abrasives during storage.

Most successful results have been with the use of special wrappings, containers, or other packaging elements. For example, U. S. 2,209,715 describes the use of a hermetically sealed container to maintain proper moisture content in a coated abrasive. However, most known means for accomplishing the desired moisture protection are unsatisfactory either because (a) special wrappers or the like are required which are too costly to be of much use commercially or (b) because once the first portion of coated abrasive has been withdrawn from the package, the moisture protection quality of the package is destroyed and the remaining portion of coated abrasive is no longer protected.

A principal object of this invention is the provision of new methods for protecting coated abrasives against moisture change during handling, storage, and use of only a portion of the total package of coated abrasive. Other objects include:

(1) The provision of new forms of coated abrasive packages.

(2) The provision of new forms of coated abrasive rolls in which the coated abrasive is protected against moisture change during handling and storage even in varied humidity atmospheres.

(3) The provision of such forms of coated abrasive rolls from which portions of the coated abrasive may be withdrawn without destroying the moisture protection qualities of the remaining roll.

(4) The provision of new methods which are very inexpensive and easy to carry out for handling coated abrasives to protect them against moisture-content change.

(5) The provision of new coated abrasive packages which use only relatively small amounts of packaging materials.

(6) The provision of new coated abrasive packages which are particularly useful for the handling of large rolls of coated abrasives, e. g., drum sanding fiber or similar bulky coated abrasive units, and which permit the abrasive to be used bit by bit without disturbing the remaining package or its moisture protection qualities.

(7) The provision of packages of coated abrasives especially useful in making overseas shipments because of the lightness of weight of the packaging elements per se and the excellent protection against moisture change given the coated abrasives even in very damp climates which are normally encountered in the tropics and semitropics.

Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific eX- amples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

These objects are accomplished according to the present invention by taking a sheet or web of coated abrasive which it is desired to package, rolling the sheet or web up into a cylindrical roll and then spraying, or otherwise coating, the two ends of the roll with a nontacky, substantially moisture-impermeable, resinous base coating. The coating used is compounded so that it is sufiiciently adhesive to the end of the roll that it will remain intact thereon during all normal movement encountered in use and shipment, and is sufliciently co hesive that the pulling off of separate layers of abrasive sheet from the roll does not pull apart or otherwise destroy the remainder of the coating or disturb its adhesion to the roll ends.

Only the roll ends need be coated with the resinous base coating. Surprisingly, it has been discovered that just coating the ends of the roll with the moisture barrier coating keeps the roll substantially at a given moisture content even when stored in atmospheres which vary greatly in moisture content. If desired, the entire roll can be coated, but this has been found not to add materially to the moisture protective value of the package for normal use conditions and considerably increases the cost.

A more complete understanding of the packages of this invention and the methods used to obtain them may be had by reference to the accompanying drawing in which:

Figure l is a diagrammatic perspective view of one form of apparatus used to perform the methods of this invention.

Figure 2 is a perspective view of a packaged coated abrasive roll of this invention from which a sheet of abrasive is being withdrawn without destroying the remainder of the package.

Figure 3 is a side sectional view of the roll shown in Figure 2.

Figure 4 is an enlarged, fragmentary sectional side view of a modified form of a coated abrasive package of this invention.

Referring in detail to the drawings, a coated abrasive package according to this invention consists of a roll 2 of a coated abrasive sheet 4 provided on each end with a non-tacky, moisture barrier, resin coating 6. The roll shown in Figure 3 also includes a core 8, which is often used, especially with large rolls, but which can be eliminated.

The coating of the roll ends can be accomplished in many ways, e. g., the coating may be brushed or troweled on the ends. However, the best balance between adhesion to the roll and cohesion of the coating is obtained when it is sprayed on the ends.

The spraying can be done by hand or many types of automatic or semi-automatic machines may be used. One form the apparatus may take is shown in Figure 1. Here rolls 2 of coated abrasive are delivered to a coating station from the left by the conveyor 10. A spray head 12, held at an adjustable height upon the stand 14, is positioned on either side of the conveyor 10. The spray heads 12 are equipped with air inlets 16 and coating solution inlets 18. The heads 12 spray coating material 20 onto the ends 22 of the rolls 2. This coats the ends of 3. th rolls h. he oa in 6 hich. new in th case of rolls with very large diameter cores, even covers up the core portion of the roll.

Use of single spray heads 12 on each side of the iconveyor is illustrated, but, if the speed of operation or characteristics of the spray demands, a plurality of spray heads may be used on each side. The operation is preterablyconducted to give a coating *6 :of between about i005 and .940 inch in thickness.

Under some circumstances, it may not be possible to get with one layer a protective coating which will have the desired moisture barrier properties and at the same time be sufticiently adhesive to hold onto the roll end and cohesive enough to remain intact when portions of the abrasive sheet are withdrawn. Also, with :a single layer end coating, there is the possibility microscopic solvent holes may exist in the single layer which can be compensated for by subsequent layers. In such cases, the desired result can be obtained by use of a multi-layer coating. The bottom layer may be the same as the succeeding layer or layers, or separate layers formed from different coating compositions may be used in forming the new packages.

A multielayer type packagemay take the form shown in Figure 4 where the roll 2 is coated on the end 22 with an inner layerj2-4 and an outer layer 26. The inner layer 24 contains a reinforcing member .28 which consists of an open mesh cloth, e. g., cheese or leno cloth, about which the coating layer 24 has been sprayed.

For-best results, the coated abrasive sheet is conditioned to the optimum moisture content before application of the end coatings. This can be done by storing the prewound rolls in a controlled atmosphere of about 40 to 50% R. H. at about 70 F. or by blowing air of this moisture content through an end of the roll. However, it is even better :to condition the sheet before rolling on a rewinding :Orslitter machine by hanging :in a-rack with the specified controlled atmosphere.

The :process is not limited to the packaging of any given :size :rolls, but may :be used with rolls of all sizes. In the past, large rolls have presented the most trouble because they require large amounts of wrappings, which is-Ja major' problem ffromit'he cost and labor viewpoint, and because they are generally used up more slowly after the initial removal \of abrasive sheet, than is the case with smaller rolls. For example, rolls of drum sanding fiber. which is :principally used :by the plywood making industry, may be two or more feet in width and several feet in diameter. Furthermore, the purc'hasenof such rolls 'uses the coated abrasive up bit by bit so that the roll may be stored in widely varied humidity conditions before it is used .up. Themethods :of this invention permit such products to be packaged so that the abrasive sheet will always be in optimum condition when Withdrawn for use regardless of the conditions or length of storage. Large rolls, such as the so-called Jumbo-rolls, may also be end-coated for storage and handling prior to rewinding and slitting by the new methods. Likewise, small rolls, e. g., .1 inch width by 100 foot rolls, may be packaged using the methods of this invention.

A wide variety of coating solutions or dispersions may be used to form the subject package coatings. Resins from the vinyl chloride copolymers of vinyl acetate or vinylidene chloride class are particularly suited for use as the resin bases for the coatings.

Suitable compositions for spray coatings are:

Example 1 Material: Percentage Vinyl acetate-vinyl chloride copoly-mer 85 to 90% vinyl chloride) i -5 to 25 Plasticizer, e. g., trietbylene glycol iii-'2- -j vT T. ?7 Z TT T.T 5, A "Volatile solvent, e. g., acetone 60 to 90 E c zz e 2 Percentage Vinyl acetate-vinyl chloride copolymer 15 to 25 Plasticizer, e. g., dibutyl phthalate 10 to 20 Hydrocarbon solvent, e. g., toluene 40 to 60 Ketone solvent, e. g., methyl isobutyl ketone 5 to 25 Example 3 Vinyl chloride-vinylidcne chloride copolymer (40 to vinyl chloride) 10 to 2'5 Plasticizer, e. g., dialkyl phthalate 10 to 25 Solvent, e. g., volatile'ketone and ester mixture.. 50 to 80 Example 4 Material:

Vinyl chloride-vinylidene chloride copolymer (50% vinyl chloride) l5 Dialkyl phthalate l5 Solvent, e. g., methyl ethyl ketone 69 Aluminum metal pigment powder '1 Examples of other classes of resinous materials from which components for the coating compositions may be taken include: polyvinyl .acetal .resins; acrylic resins; rubhers, which includes naturaland synthetic rubbers, such as .butadiene copolymers of styrene or acrylonitrile, butyl rubber, etc.;'-rubber hydrohalides; halogenated rubbers; polyethylene; halogenated polyethylene and mixtures of these are best suited for an entire coating or the inner layer of mold-layer coatings. For the outer layers of multialayeri-coatings, additional examples of usable resins include cellulose esters; .cellulose-ethers; alkyd resins; and

the like.

Plastici zers are usually included to import the proper balance of adhesiveness and cohesiveness as is known in the art to give non-tacky, flexible, strippable films. The volatile solvents, e. g., :ketones, aromatic hydrocarbons, ethers, esters, halogenated aliphatic hydrocarbons, etc, are, chosen according to known techniques to give the proper degrceof coverage without :undue penetration into the 110.11 layers or tooslow drying of the coated film.

Pigments, dyes, .fillers and the like may be incorporated in thecoating compositions :if desired. Inclusion ofsmall percentages, e. g., 0.1 to 5% of a pigment-type aluminum metal powder has been found .to. give compositions which produce final packages with efine qualities.

Sutficient solvent evaporates in passing from the spray gun totberrollend or on standing :that the resulting film is sufficiently firm shortly after spraying that it may be handled. However, .if needed, infra-red lamps, drying tunnels, or equivalent means may be added to the coating equipment :todry and harden the end coatings.

The coating composition is thinned with sufficient solvent to givethe proper viscosity for spraying, or other coating operation used. When spraying is used, the gun or spray head is best held about six'inches from theend of the roll and at a '90 angle to the working surface. 'il hespray is preferably applied in multilayers rather than a single heavy layer to avoid the possibility of solvent holes-in the-resultingfbarrier film.

-New :methods for handling rolls of coated abrasives have :been described which protect the roll contents againstmoieturecontentchange. The new methods make possible the =formation-of coated abrasive packages which provide the moisture protection not only when the package isnew, but right-ondown to the final-portions of the roll as sections of the abrasive sheet are removed from the roll and used. Furthermore, these new roll packages use only a very small amount of packaging materials, thus making them inexpensive as well as light and compact.

"realm:

A i l at a shee Qf s ated abrasive hich has a tecdca y' op c sup mo s ure hen ored ia is -hum i t! a m sphere -and t l se m ist r hen hel n. dr atmospheres comprising a substantially continuous, moistum-impermeable, non-tacky, resinous base coating covering each end thereof, the remainder of the roll being free of such coating whereby the roll of coated abrasive is protected against changes in moisture content during storage in atmospheres of varying moisture content and portions of the coated abrasives may be pulled from the roll without destruction of the moisture barrier qualities of the remaining package.

2. A coated abrasive package as claimed in claim 1 wherein said coating comprises a plurality of layers.

3. A coated abrasive package as claimed in claim 1 wherein said coating comprises an inner flexible layer and an outer, less flexible, more moisture-impermeable layer.

4. A coated abrasive package as claimed in claim 1 wherein said coating comprises a reinforcing layer of open-mesh cloth imbedded in the body of the non-tacky coating.

5. A coated abrasive package as claimed in claim 1 wherein said coating comprises predominantly a vinyl chloride copolymer.

6. A coated abrasive package as claimed in claim 1 wherein said coating comprises predominantly rubber.

7. A packaged coated abrasive sheet which has a tendency to pick up moisture when stored in high-humidity atmospheres and to lose moisture when held in dry atmospheres comprising a roll of said coated abrasive sheet and a continuous, moisture-impermeable, non-tacky, resinous base coating upon each end of the roll, with the remainder of the roll being substantially free of such coating, said coating being fixed directly to the ends of the rolls with sufficient adhesive force that it remains intact thereon during shipment and storage, protecting the roll against changes in moisture content, although portions of the coated abrasive sheet may be pulled from the roll without destruction of the remainder of said coating and the moisture barrier qualities of the remaining package.

8. A method for packaging lengths of coated abrasive which has a tendency to pick up moisture when stored in high-humidity atmospheres and to lose moisture when held in dry atmospheres which comprises adjusting the moisture content of a sheet of said coated abrasive by subjecting the sheet to a controlled atmosphere having a moisture content equivalent to air with a relative humidity of about to at F., rolling such moisturecontent adjusted sheet into a cylindrical roll and spraying a resinous base coating composition on the ends of said roll without spraying any appreciable amount of said coating onto the remainder of the roll to form a nontacky, moisture-impermeable, resinous base coating directly on the ends of said roll.

References Cited in the file of this patent UNITED STATES PATENTS 1,457,625 Freyclberg June 5, 1923 1,687,905 Stevenson Oct. 16, 1928 2,036,960 Brenn Apr. 7, 1936

Claims (1)

1. 8. A METHOD FOR PACKAGING LENGTHS OF COATED ABRASIVE WHICH HAS A TENDENCY TO PICK UP MOISTURE WHEN STORED IN HIGH-HUMIDITY ATMOSPHERES AND TO LOSE MOISTURE WHEN HELD IN DRY ATMOSPHERES WHICH COMPRISES ADJUSTING THE MOISTURE CONTENT OF A SHEET OF SAID COATED ABRASIVE BY SUBJECTING THE SHEET TO A CONTROLLED ATMOSPHERE HAVING A MOISTURE CONTENT EQUIVALENT TO AIR WITH A RELATIVE HUMIDITY OF ABOUT 40 TO 50% AT 70* F, ROLLING SUCH MOISTURECONTENT ADJUSTED SHEET INTO A CYLINDRICAL ROLL AND SPRAYING A RESINOUS BASE COATING COMPOSITION ON THE ENDS OF SAID

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