US2485295A - Pack of abrasive coated sheets - Google Patents

Description

Oct. i8, 1949. A. J. LARsoN PACK 0F ABRASIVE COATED SHEETS Filed Sept. 17194'7 maar oa. 1a, man

UNITED STATES PATENT OFFICE 2,485,295 rack oF ABnAslvi: coa'ran snEE'rs Adolph 3. Kanon, Chicago, Dl.. I appucaannfseptemser rr, ist?, sensi warmere 2 ce. (ci. zoe-'sei This invention relates to abrasive coated' sheets, of the character commonly known as emery cloths, sandpapers, and the like. More particularly, this invention relates to an abrasive coated paper sheet, and to a pack of such abrasive coated paper sheets, and to holders for use with the new abrasive coated sheets.

In the die makers art large quantities of abray sive coated paper sheets, such as sandpaper, emery cloth and the like, are used for polishing ridges and other rough surfaces in die mold cavities and the like. To accomplish this result die makers frequently wrap a piece of such abrasive coated paper, such as sandpaper, about a pencil or piece .of wood for the purpose of providing a support for forcing the abrasive sheet into and around the hills and valleys in such die mold cavities and the like, during the polishing operation. This practice is dimcult and is hard on the operators hands and fingers, frequently causing them to become scratched and cut.

There is currently available upon the market a device for holding an abrasive coated paper sheet, such as a sheet of sandpaper, upon a cylindrical holder for use in polishing the ridges and other irregular and rough surfaces in die mold cavities and the like. However, this prior holding device is of relatively involved and complicated and correspondingly expensive construction and requires considerable time and effort in mounting an abrasive sheet thereon and in removing it therefrom.

An object oi the present invention is to provide an abrasive coated strip or sheet comprised of e. carrier or base sheet of paper or the like having a pressure-sensitive adhesive on its bottom or non-abrasive coated surface so that it may be readily formed around and attached to a suitable supporting element for use by die makers in polishing die mold cavities, and for other purposes.

Another object of the invention is to provide a novel pack of abrasive coated paper, or like sheets, adhesively heldftcgether in the form of a pack of adhesive engagement or contact between the abrasive coating on the upper surface of each underlying sheet with the pressure sensitive adhesive on the bottom or non-abrasive coated surface of each carrier or base sheet to the end that the abrasive coated paper sheets may be made in suitable sizes `or dimensions and sold and dirstributed as a pack thereof and each sheet readily removed from the pack as and when desired.

An additional object of the present invention is to provide novel holders, hereinafter described, which are especially adapted for use by die mak- 4same or equivalent principles may be used and structural changes may bevmade asdesired by those skilled inthe art without departing from the present invention and the purview of the appended claims.

Fig. 1 is a perspective view of a pack of abrasive coated sheets made in accordance with and emhodying thepresent invention, the uppermost sheet in the pack being partially peeled back at one end thereof to illustrate the manner in which the sheets may be separated from the pack, one by one, when required for use i Fig. 2 is an enlarged transverse sectional view. on line 2--2 in Fig. 1, illustrating a typical and preferred construction of one of the new abrasive coated sheets;

Fig. 3 is an enlarged transverse sectional view, similar to Fig. 2, but illustrating a modified form o the invention; I

Fig. 4 is a top plan view illustrating a holder or support with and upon which the new abrasive coated sheet may be used and which is especially adapted for use by die makers in polishing the surfaces of die mold cavities and the like;

Fig. 5 is a sectional view on line 5 5 in Fig. 4, illustrating the `manner in which the new abrasive sheet is mounted in position of use upon the holder illustrated in Fig. 4;

Fig. 6 is a top" plan view illustrating another type of holder which may be used for holding the new abrasive sheet, and which is especially adapted for use by die makers in polishing the ridges and other irregular surfaces inaiie mold cavities and the like; and f Fig. 7 is a transverse sectional view, on line "i-l in Fig. 6, illustrating the manner in which the abrasive sheet of the present invention is mounted upon the holder shown in Fig. 6. K

A pack of abrasive sheets made in accordance with and embodying the present invention is shown in Fig. 1, wherein it is generally indicated at it, and comprises a purality of superimposed abrasive coated sheets each of which may eme new abrasive coatedk glue, over and upon which a layer I of inelyy divided abrasive particles is laid. The abrasive particles I5 may be composed of sand, emery, silicon carbon, or the like.

In the practice of the present invention I apply to the bottom a non-abrasive coated surface oi! the paper or like base sheet or sheet I3 a coating or lm of normally tacky and pressuresensitive adhesive I6. This coating or illm of normally tacky, pressure-sensitive adhesive `I6 may be applied directly to the bottom or nonabrasive surface of the paper or like base sheet or carrier, as in Fig. 3, or it may be applied to an auxiliary base sheet or carrier I'I, asl in the form of the invention illustrated in Figs. 1 andy 2. This auxiliary base sheet or carrier I1 may be a thin layer of cotton, such as crinoline, to the inner l surface of which a layer or coating I8 of'normally tacky, pressure-sensitive adhesive is ap- -plied so as to adhesively secure the auxiliary base sheet or carrier I1 to the back of theabrasive coated sheet Il.

The normally tacky. pressure-sensitive adhesive lms I6 and I8 may be made according to The latex crepe, zinc oxide and pigment are milled `for 10 minutes, at a temperature of about 14o-150 F., and the resulting base is cut into small Vpieces and churned with the antioxidant, rosin and solvent for about hours at a temperature of -10011".

The indicated heptane may be substituted lor by another volatile rubber solvent such as benml or naphtha. It will be understood that the proportion oi solvent may v'be varied to produce the desired viscosity of the adhesive solution, which the disclosure of United States Letters Patent No.

2,206,899 granted July 9, 1940 to Waldo Kellgren on Method of making pressure-sensitive adhesive sheets. The pressure-sensitive adhesive material I6 or I8 may be of any character suitable for the purposes of the present invention.

It may contain -a reinforcing pigment capable,

of penetrating into the paper, and may be colored by a pigment or dye. The following examples illustrate .suitable adhesive compositions which may be used in the practice of the present in.

vention, all parts being by weight:l

Example No. 1

Parts by weight Latex Crepe 10o Zinc oxide Rosin 100 Heptane (volatile solvent) 40G-600 The latex crepe and zinc oxideare milled on a rubber mill for 10, minutes, at a temperature of about -150 FL, and the resulting base is cut into small pieces and placed in a suitable churnV with the rosin and solvent. The mixture is mixed until homogeneous, involving mixing for about- 40 hours. l Example No. 2

' Parts by weight Latex crepe 132 Zinc oxide Blue pigment mixture 39.5 No. 10 woodrosin 72.5 Flectol B (antioxidant) 1.5 Heptane (volatile solvent) '150 The blue pigment mixture is exemplined -by Du Pont rubber blue Y. D, a milled mixture of equal parts latex crepe and dry blue pigment. This pigment may be omitted. ,Y

should be suillciently low to insure thorough saturation of the paper base sheet or carrier I3 and yet high enough to introduce sufllcient solids so as to properly unify the paper. The adhesive solution produced according to these examples is a thick viscid liquid. .The amount of hydrocarbon solvent required may be reduced by incorporating alcohol as a viscosity-reducer, which may be denatured ethyl alcohol (for example containing 5 volumes of methyl alcohol or ethyl acetate per 100 volumes of\ prooi yethyl alcohol) or may be methyl alcohol, and which may be used in amount equal to 10 to 20% of the hydrocarbon solvent.

The Flectol B (a liquid condensation product of acetone and aniline) is usedfas'an antioxidant to improve the rubber aging qualities. Other suitable antioxidants or age-resistors are; Flectol H (a solid condensation product of acetone and aniline), Solux (p-hydroxy-N-phenylmorpholineie, Agerite Resin (aldol-alpha-naphthylamine reaction'J product), Antox, betanaphthol, Agerite Alba and Agerite White. Those which are soluble in the rubber solvent may be added directly, otherwise they may be J milled into the rubber during the initial milling.

The coloring pigment'serves also as a reinforcing pigment, as does the zinc oxide, giving greater cohesiveness '(rmness) to the adhesive. These pigments maybe omitted or reduced in order` to produce transparent adhesive coatings and a transparent or semi-transparent adhesive sheet product. The adhesive impregnant with which the paper is saturated serves to transparentize it.

Example No. 3

y Parts by weight Isobutylene polymer medium 200 Isobutylene polymer low 200 Soft cumarone resin 80 I`Ieptane i600 yThe isobutylene polymers are resinous materials, the one designated medium having a molecular weight ofabout 80,000 and is transparent and rubbery -in appearance. The one Hydrogenated methyl abietate 0.2 75 Heptane j designated low has a molecular weight of about 14.000. The ingredients are placed in a churn and mixed until homogeneous.

The cumarone resin acts as a tack-producer, as does the lower isobutylene polymer. The latter may be omitted and the stated proportion of cumarone resin retained or increased, and the cumarone res/in may be substitutedfor by wood rosin or other tack-producing resin.

' Example No. 4

' Parts by weight Isobutylene polymer "medium l Zinc oxide 0.5 Para-toluidine redv 0.2 Wood rosin 0.5

The isobutylene polymer, zinc oxide and coloring ingredient (illustrated by para-toluidine red) are first milled on a rubber mill until a uniform plastic composition is secured. This plastic mass is then cut into pieces and placed in a suitable 5 churn with. the balance of the ingredients and churned until a homogeneous solution is formed. The wood rosin serves as a tack-producing agent, so that normally tacky and pressure-sensitive adhesive coatings will be formed. The hydrol0 genated methyl abietate serves as a plasticizer and may be omitted. l

A suitable holder for using the new abrasive sheet is illustrated in Figs. 4 and 5 of the draw,-

ing, and comprises a resilient and substantially cylindrical holder base or body I9' which has a centrally formed cavity formed therein for the reception of an internally threaded anchoring ferrule 2I to which an externally threaded shaft 22 is attached. A radially extending slot 20 23 is formed in the holder base or body I9, as shown in Fig. 4.

In the use of the new abrasive sheet II, upon the particular type of holder shown in Figs. 4

and 5, the sheets or strips II maybe preformed 25 strip may then be inserted into, and adhesively secured in, the radially extending slot 23 in the substantially cylindrical holder base or body I9 and the remaining length of the strip or sheet, with the pressure-sensitive adhesive coating I6 disposed inwardly, woundy about the substantially cylindrical holder baseor body I9 in adhesive contact therewith. The pressure-sensitive adhesive layer I6 will thus cause the entire abrasive coated paper strip or sheet II to adhere to the peripheral surface of the holder base `or body I9. The thus completed tool, shown in Figs. 4 and 5 may be attached. by means of the shaft 22. to a chuck, or ther like, of any suitable portable motor driven tool and the holder I9 with the abrasive sheet II 'adhered thereto rotated in con- 50 tact with/the surface of a die cavity in a die mold or the like so as to polish the ridges and other rough surfaces therefrom. l

Another suitable form of holder upon and with which the new abrasive sheet I I may be employed is illustrated in Figs. 6 and 'l of the drawings and comprises a holder member including a substantially conical-shaped or cup-shaped exible body 26. which may be made of rubber 'or like resilientmaterial.-Thebody25hasabase29ln w which a recess 21 is formed for the reception of an inwardly threaded ferrule 28 to which an externally threaded shaft 29 is attached. The bodyhasanopenendormouthlll.

In the use of the form of the holder shown g5 in Figs. 6 and 'l the abrasive sheets or strips II may be preformed to proper size and disc shape ortheymaybemadeinanydesiredsizeand shape and peeled or separated from the pack I0 and cut to paper size. in the formA of a disc. corresponding to the size and shape -of the mouth of the substantially cup-shaped exible holden body 25. The disc-shaped abrasive-coated sheet II may be adhered to the peripheral edge or 30 of the latter by means of the pressure-sensitive-- adhesive coating I6 thereon, with the body'jof the abrasive -disc I I stretched across the openfendi.-

or mouth 3,0 of the holder body `25. The thus x completed tool, shown in Figs. 6 and 7, may A be attached, by the shaft 29, to a' chuck or the .like of a portable electric power driven tool and rotated and used by a die maker for polishingthfe.;` ridges and hills and valleys in die mold cavitiesj 1 f and the like. During this usage the exible cupf shapedk body 251will flex readily and enable the abrasive coated disc-shaped abrasive sheet II mounted thereon to penetrate into the valleys and other places in the die mold cavity into which it is impossible to penetrate effectively by means of an unmounted abrasive sheet or by means of any tool now knownto or used by die makers.

It will thus be seen from the foregoing description, considered in conjunction with the accompanying drawing, that the present invention thus accomplishes its intended objects, and has the desirable advantages and characteristics, including those hereinbefore pointed out and others which are inherent in the invention.

I claim: 4 1..As a new article of manufacture, a pack of abrasive coated sheets arranged in superimposed relationship and each comprised of a exible base sheet or carrier having on one side thereof y abrasive sheets arranged in superimposed relationship and each comprised of a flexible paper base sheet or carrier having ony one side thereof a coating of nely divided abrasive particles'adhesively secured to the said paper base sheet or carrier and having on its other and non-abrasively coated surface a iilm of a normally tacky, pressure-sensitive adhesive, the said abrasive sheets being adhesively but releasably secured together in superimposed relationship by adhesive engagement between the finely divided abrasive particles on each underlying sheet with the normally tacky pressure-sensitive adhesive on the next adiacent sheet thereabove.

ADOLPH J. LARSON.

REFERENCES CITED i The following references are of record in the file of this patent:

UNrrED STATES PA'I'ENTs Number A- Name Date 1,814,553 Hope July 14,1931 v 2,018,611 Feuerstein Oct. 22, 1935 2,059,583 Jackson et al Nov. 3. 1936 2,259,685 Elsloo Oct. 21, 1941 Kirchner June 16.11942

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