GB2200592A - Method of manufacturing a laminated facestock and carrier stock and an adhesive therefor - Google Patents

Description

220 0 5 9 2 Method of Manufacturing a Laminated Facestock and Carrier

Stock and an Adhesive Therefor, The invention relates generally to a method of manufacturing a facestock that becomes releasably secured to one sideof a carrier stock and to an adhesive therefor..

C" There is a great marketplace demand for paper and synthetic products which are used for dry tags, coupons, temporary membership cards, and the like. These products are used in a number of specialized applications. As one non-limiting examplej such products may take the form of point-of-purchase coupons which are printed on two sides, die-cut, stripped, and automatically.

applied to a product package. When a consumer removes the coupon from the-package, it must separate cleanly, leaving no trace of adhesive on either the coupon or the package. Temporary membei;ship cards on pressure-sensitive tag stock are also printed on two sides, die-cut, stripped, and automatically applied to a substrate which may be a business form or direct response mailing piece. The consumer must be able to easily remove the card from the substrate, and no exposed adhesive must remain on either.the substrate or the card.

Va.cestock that is suitable-for..computer printing can be printed on one or two sides, die-cut, stripped, marginally punched, and either rewound on a roll, fan-folded, or sliced into a 1 2/M0599 :2 plurality of discrete labels. The rewound, fan-folded, or discrete labels may be then imprinted by a computer printer. Again, as individual tags or labels are removed for use, there must be no exposed adhesive on either the back side of the tag or the stripped portion of the carrier stock or liner.

One current method of manufacturing such coupons or cards is a process performed by Techhicote Mfg. Co., Miamisburg, Ohio, which comprises bringing together two laminar components, a substrate composite, and a facestock composite. The substrate is a five-layer composite. Three of the layers are film or paper, and the other two are bonding materials or adhesive. Particularly, the substrate composite comprises a first layer of clear film, a chemical bond as the second layer, another layer of clear film, a TP 110 permanent adhesive, and a forty-pound silicon liner.

The facestock composite is a three-layer product, and includes a first layer for receiving printi-ng or graphics, a patterned adhesive, and a liner. In order to manufacture coupons from these substrate and facestock composites, the bottom liner layer from the facestock composite is removed, exposing its adhesive. This facestock adhesive layer is then secured to the top, clear film layer of the substrate composite to form a seven-layer facestock-substrate construction. At this point, facestock graphics may be printed, the construction is die-cut, waste is removed, and the finished labels are typically rewound onto a roll for the ultimate user.

3 is When this user grasps an edge of the coupon or label to remove it from the facestock-substrate construction, the adhesive from the facestock composite sticks to the first or top clear film layer of the substrate composite, and "pulls" that clear film layer with it. In this mannerr the facestockf its adhesive, and the top layer of clear film are removed together to form the coupon. The coupon that is removed thus includes the facestock from the faqestock composite as its top layer; the top clear film layer from the substrate as its bottom layer; and the adhesive from the facestock composite as an intermediate layer. Thus, neither the coupon, whose backside comprises the clear film layer, nor.the substrate, whose front side comprises a non-tacky chemical bonding layer, is tacky or sticky to the touch.

The main disadvantage of the Technicote method is that the number of layers or components used in each of the composites used to manufacture the label is substantial. As described, the Technicote method comprises merging two _composites, one originally comprising three layers and the. other originally comprising five layers. one of the layers of the facestock composite, the liner, is removed, discarded, and ultimately wasted.

Another method of manufacturing these coupons appears to comprise assembling a three-layer laminate including a facestock, a paper carrier sheet, and a water-based adhesive intermediate the two. This method, as it appears based upon limited knowledge by Applicants, is is used by Standard Register Company of Terre Haute, Indiana, to manufacture coupons. Although it eliminates the multiple layers required in the Technicote method, the Standard Register method appears less able to impart proper release between the facestock and the carrier sheet. Particularly, the various samples obtained by us from Standard Register and apparently made by the above-described method exhibited very high adhesion between the carrier'sheet and the facestock. As a result, the facestock curled excessively when it was removed from the carrier sheet.

An improved method of manufacturing these oroducts would lower the number of components or layers used in connection with label making, and provide adhesion levels enabling the coupons or tags to be removed from the carrier sheet without excessive curling.

Now, according to one aspect of the present invention, a method of manufacturing-a facesteck that-becomes releasably secured to one side of a carrier stock comprises (a) placing an ultraviolet-ray curable adhesive on the front side of the carrier stock; (b) overlaying the front side of the carrier stock with the facestock; and (c) curing the adhesive with ultraviolet radiation through the reverse side of the carrier stock. The Dresent method results in a facestock that may be printed upon, die-cut, and trimmed in "a conventional manner and wound into a roll or fan-foldpd into a stack of finished labels for the end user. Upon removal, both sides of the coupon or facestock and all exposed or covered portions of the carrier stock are tack-free. This is because the adhesive is cured with ultraviolet radiation to a tack-free state. "Tack-free," as applied to the product made by this method, is intended to mean lacking in a sticky or adhesive quality or condition.

The present method may be employed on a conventional label press using readily available ultraviolet curing unit accessories. The finished fan-folded or roll material may be punched to be pin-fed into a computer printer, and printed in the conventional manner.

The invention also comprises, according to a second aspect, a photoinitiatable or phot-opolymerizable adhesive comprising (a) a photoi, nitiator, (b) a polyurethane, (c) triacrylate; and (d) difunctional monomer. Such an adhesive provides suitable release characteristics and cures through the carrier stock, enabling the manufactured coupons and waste from the release liner tobe tack-free. The photoinitiated adhesive or coating is preferably curable at high speeds through the carrier stock or release liner, flexible at relatively thick coatings of up to.0254 mm (1 mil), should preferentially adhere upon curing to the facestock rather than to the release liner, and should be capable of "wetting out" the surface of the reease liner to prevent air entrapment whi ch could result in a non-uniform coated surface.

i 1 1 6 The invention may be carried into practice in various ways and a method of manufacturing a facestock in accordance with the invention and adhesives in accordance with the invention and suitable for use in the method will now be described by way of example with_reference to the accompanying drawings, in which:

Fig. 1 is a side view of a conventional flexographic press modified to operate according to the method of the present invention; Fig. 2 is a side view of the facestock and the carrier stock used in the method as they are brought together at a pair of nip rolls at station A of Fig. 1, and as they pass through the ultraviolet curing unit shown in Fig. 1; and Fig. 3 is a perspective view of the finished product made by the method and showing a trimmed tag being removed from a finished product material web that has been pre-punched for computer pinwheel feeding.

Referring now to Figs. land 2 of the drawings, there is shown a Mark Andy Model 4120 label printing and die-cutting press that may be used for the present method. The Mark Andy press, manufactured by Mark Andy Company, Chesterfield, Missouri, is generally designated by the numeral is 1 10, and receives a continuous web 12 of carrier stock material originating at one remote end of the label press. The carrier stock is preferably a semi-bleached densified kraft-based stock with a basis weight of 54 pounds. and was chosen to utilize existing die tooling. Any suitable carrier stock may be used. However, the carrier stock must transmit, through a single layer, a certain minimal amount of ultraviolet radiation. Through the presently-utilized kraft-based stock, transmittable ultraviolet radiation was found to be in a wave-length range of 250-400 nanometers. The amount of the radiation through the single layer of carrier stock must be sufficient to cure the ultraviolet- ray curable adhesive at normal label press speeds. The preferred adhesive _formulation used in the present process was found to adequately cure at web speeds of 200 feet-per minute,-61 m/min.

The web of carrier stock 12 ultimately reaches station A, where the ultraviolet-ray curable or photoinitiatable adhesive is applied to the front side 15 of the carrier stock by rotating roll 18. Adjacent the adhesive-applying station A is the facestock-unwind stand 20, through which a web of facestock 22 is unwound from facestock roll 24. A pair of nip rolls 26 and 28 driven at web speed are spaced a small distance apart, and the adhesive-covered web of carrier stock 12 and the facestock 22 are brought into engagement at nip rolls 26 and 28.

The selection of facestock will be largely dependent upon the desired print-receiving characteristics and the ability of the zr, is 1 flexographic press to successfully remove trim. One suitable facestock that may be used in association with this method is a 90-pound index stock. This stock provides good computer printability, and the high internal and tensile strength characteristics for wide-web die cutting and trim removal.

The nip rolls 26 and 28 function to -effect a uniform adhesive layer thickness acrbss the entire facestock- carrier stock interface. It has been found that an adhesive thickness of. 0254 m approximately(one miVshould be applied to the carrier stock 12 by the rotating roll 18, and that the spacing between the nip rolls 26 and 28 should ensure that this adhesive layer is somewhat compressed by their combined action.

Prom the nip rolls, the combined carrier stock/facestock web 12/22 enters an ultraviolet-ray curing unit-30. The curing unit 30 provides ultraviolet lamps 31 enabling passage of ultraviolet rays through the reverse side 13 of the carrier stock web 12. The reverse side 13 is the side that has not been overlaid with adhesive. The ultraviolet curing unit is con-ventional, and may be obtained from Mark Andy for the 4120 press. The unit is a 'Mark Andy Model 88 ultraviolet curing system', and contains two 305 mm (12-inch) long ultraviolet lamps having a lighting value of 118 W/cm (30C watts per inch). Replacement lamps are available from UV Process Supply Co., Chicago, Illinois, as Part No. H54C/18A. These ultraviolet lamps will provide sufficient curing exposure when the combined carrier stock/facestock web 12/22 passes 1 q is through the ultraviolet curing unit 30 at a web speed of approximately 61 m (200 feet) per minute.

As the composite-carrier stock/facestock web 12/2.2 leaves the ultraviolet curing unit 30, it passes over an idler roller 32 en route to a die-cut station B. The die-cut station includes a rotary cutting die 36 and a driven die-cutting base roll-34 spaced slightly below rotary cutting die 36. The spacing is such that as the composite carrier stock/facestock web 12/22 passes between the cutting die 36 and the die- cutting base roll 34, the cutting die 36 cuts through the facestock web 22 without cutting into the carrier stock 12. The cutting die 36 may be arranged to cut the facestock 22 to form label portions 38 of any suitable dimen.sion and shape. The die-cut label portions 38 are surrounded by waste portions which are removed from the web of carrier stock 12. The die-cut composite web of facdstock and carrier stock then passes through a hole-punch station C, where holes 40 are punched into the web's periphery to enab le the finished product to be fed through a computer pin-fed tractors. Prom hole-punch station C, the die-cu"t"- Composite web 12/22 is fed over a pair of waste removal rollers 42 and 44, where the waste portions of the facestock web 22 are stripped from the surrounded label portions 38 to form a waste portion web 46. Web 46 is fed upwardly over a pair of idler rollers 48 and 50 to a waste take-up roller 52 on which the waste web 46 is wound.

Removal of the waste web 46 from the carrier stock web 12 provides a finished product label material web 54 which may be fed to a ccross-perforation station D. At station D, cross-perforations are placed into the finished product label material web 54 so that the finished product may be fan-folded at a separate station (not shown). It is understood to those skilled in the art that rather than being crossperforated for fan-folding, the finished product label material web 54 may be fed to a product-rewind assembly, where the web 54 is rewound onto a rewind roll (not shown). Alternatively, it will be understood that instead of winding the finished product web or fan-folding it, the web could be sliced into a plurality of discrete labels, each provided with its own backing sheet. Purther, while in this embodiment of the invention no printing is described, it will be appreciated that printing stations may be provided for printing the facestock on the front and back or the finished labels with any desired indicia, or that the facestock front and back may be printed prior to its placement at the facestock unwind stand 20.

Referring now to RIG. 3, in use the label portions 38 may be readily peeled from the finished product label web 54. The adhesive used is such that after ultraviolet curing, peeling away of the label portion 38 from the finished product material web 54 yields a label portion 38 having a backside 56 which is tack-free. Purther, the portion. of carrier stock web 12 beneath the label portion 38 will also be tack-free, as will the area of the carrier stock web 12 surrounding the label portions 38 and beneath the previously-removed waste web 46. The backside 56 of label portion 38 may have been pre-printed with i 11 is indicia so that it may be used, for example, as a two-sided hang-tag in connection with the sale of garments. Further, because both the label portion -38 and the finished product.label material web 54 are tack-free, the product made by the present method will not ngUM Ur)n computer- operated printers and their associated label feed machines.

It was-decided to formulate in-house a photoinitiatable adhesive for use in the present method. A UV-curable coating that could be applied to the carrier stock was preferred. As stated above, the UV-coating needed to be readily curable through the carrier stock, exhibit flexibility at relatively thick 0.0254 mm (1-mil) coatings adhere to the facestock rather than to the carrier stock, and be capable of "wetting out" the surface of the carrier stock to prevent air entrapment which could result in a non-uniform coated surface.

Applicants tested approximately 14 different formulations of various components before finding an ultraviolet-ray curable adhesive that exhibited the proper release and visual characteristics for a paper tagstock application. The cured adhesive should permit curl-free release of the facestock from the carrier stock at 9.8-29.59/cm(2575 grams per inch), as read from a TLMI release tester, at both 30.5 cm (12 inches) per minute and 30.5 m (1200 inches) per minute. The adhesive cures to the back of the facestock. When the label portion 38 is peeled from the fitiished product label material web 54, the backside 56 of the label should have a uniform, transparent, spot-free visual appearance.

12- is The ultimately preferred UV-curable adhesive was a blend of components, including monomers, oligomers, and a photoinitiator. Generallyr this adhesive comprised an acrylated polyurethane, an acrylate ester, a triacrylate, a difunctional monomer, a photoinitiator, and a wax grind. Particularly, this adhesive comprised CMD 8800, an acrylated polyurethane manufactured by Celanese Corporationt Louisville, Kentucky; Celrad 7100, an acrylate ester manufactured by Celanese Corporation, Louisville, Kentucky; glycerol propoxy triacrylate (GPTA) manufactured by Celanese Chemical, Dallas, Texas; tripropylene glycol diacrylate (TRPGDA) manufactured by Celanese Chemical, Dallas, Texas; Tone M-100, a caprolactone manufactured by Union Carbide Corporation, Danbury, Connecticut; Irgacure (IRG) 184, a photoinitiator manufactured by CibaGeigy Corporation, Greensboro, North Carolina; and 4118 wax grind, which is a blend of 3 parts glycerol propoxy triacrylate and 2 parts of a microcrystalline wax grind, and which is manufactured by Ink Specialties, Arlington Heights, Illinois. The wax grind itself is a microfine wax, Catalog No. MP-2F, available from Dura Commodities, Harrison, New York. The preferred ultraviolet-ray curable adhesive formulation has the following composition:

13 5.

Component CMD 8800 (acrylated urethane) Parts By Weight 38.2 Cel-rad -7100 (acrylate ester) 9_.5 -- GPTA (triacrylate.) Qk is 17.2 TRPGDA (difunctional monomer) Tone M-100 (difunctional monomer) IRGACURP 184 (photoinitiator) 4118 (wax grind) 13.3 13.3 4.8 3.7 This adhesive may be made as follows: The CMD 8800, Celrad 7100, GPTAr TRPGDA, and Tone M-100 are mixed in a heated, oil-jacketed tank at 60"C 140 P)until the viscosity of the blend has been lowered to a workable mix.

This blend is then placed in a high-shear mixer containing the IRGACURE 184, and blended for appoximately one-half hour.

rinally, the 4118 wax grind is added to the high-shear mixer and blended with the remaining ingredients for about-15 minutes.

The 4118 wax grind may be obtained from Ink specialties or blended by the formulator. To blend this wax grind, the glycerol propoxy triacrylate is placed in a high-speed dispenser, 14- is and the wax is sifted into the dispenser over a one-half hour period.

Other adhesive formulations were TMLI release-tested on the preferred facestock and. carrier stock, and the results of those tests are shown below. Some of these formulations may provide suitable release characteristics, i.e., release of the facestock from the carrier stock of 9.829.5 g/cm (25-75 g/in) at either 30.5 cms (12 inches) per-minute or 30. 5 m (1200 inches) per minute, for carrier stocks and facestocks other than those preferred in this embodiment. rormulation (N) below is also preferred, in that it resulted in suitable release characteristics for the preferrpd-facestock and carrier stock. The formulations described below and the preferred formulations were tested in a laboratory and at a web speed of 23 m (75 feet) per minute:

j 4 1 j Is TABLE 1 (A) (B) - (C) (D) (E) Uvithane 788 10.8 21.5 21.5 10.8 32.3 Celrad.

3800 21.5 10,8 10.8 21.5 ---- GPTA PP-TA 10.8 10.8 20.8 10.8 10.8 21.5 21.5 11.5 21.5 21.5 - TRPWA 21.5 21.5 21.5 21.5 21.5 V-pyrol 1 13.9 13.9 13.9 13.9 13.9 Irgacure (IRG) 651 4.5 4..5 4.5 4.5 4.5 BYK-300 FC-430 2 - drops 1.0 1.0 1.0 1.0 1.0 is TMLI release, g/in. @ 12n/ min. 17.5 18.0 19.0 19.0 25.0 1 TMLI release, g/in. @ 1200" min. 20.0 19.0 23.0 21.0 35.0 1 i ib Uvithane 788 is a polyester urethane acrylate manufactured by Morton- Thiokol, Chicago, Illinois. Celrad 3800 is an acrylate ester manufactured by Celanese Corporation, Louisville, Kentucky. PVTA is a triacrylate manufacted by Celanese Corporation, Louisville, Kentucky. V-pyrol is n- vinyl-2-pyrrolidone, manufacted by GAP Corporation, New York, New York. Irgacure 651 is a photoinitiator manufactured by Ciba-Geigy Corporation, Greensboro, North Carolina. BYK-300 is a surfactant for coatings, manufactured by BYKCHFM, Wallingford, Connecticut. VC-430 is a fluorochemical surfactant, and is a product of The 3M Company, St. Paul, Minnesota.

j i Q t 17 Table 2

CMD 8800 Celrad 3800 (P) 32.3 GPTA 10.8 PFTA 21.5 TRPWA 21.5 V-pyrol 13.9 Irgacure 651 4.5 FC-430 1.0 TMLI release, g/in. @ 120 min. 32.5 TMLI release, g/in. @ 12000/min. 39.5 f.

is Table 3 (G) (H) (I) CMD 8800 32.3 32.3 32.3 GPTA 10.8 10.8 20.8 PE-TA 21.5 21.5 --- TRPWA 21.5 21.5 33.0 Tone M-100 13.9 13.9 13.9 Irgacure (IRG) 651 4.5 4.5 4.5 FC-430 -1.0 1.0 1.0 TMLI release, g/in. @ 12n/min. 35 20 40 TMLI release, - g/in. @ 1200"/min. 40 20 39 Two (2) passes required to cure.

0 Used Uvithane 788 rather than CMD 8800.

11 1 lq Table 4 (i) (K) CMD 8800 4 1 (L) (M) (N) 32.3 32.3 22.3 32.3 32.0 Celrad 7100 GPTA 10.0 20.0 10.0 10.0 20.8 20.8 20.8 20.8 18.0 TRPGDA 33.0 23.0 23.0 23.0 22.0 Tone M-100 Irgacure 651 4118 wax grind 13.9 13.3 13.9 13.9 14.0 4.5 4.5 4.5 4.5 -5.0 ---- 4.0 TMLI release, g/in. @ 12"/min. 40 43 34 42 45 TMLI release, g/in. @ 12000/min. 40 46 38 46 45 rwo (2) passes required to cure.

1 f 11

Claims (1)

1. Claims:

   A method of manufacturing a facestock that becomes releasably secured to one side of a carrier stock comprising:

   (a) placing an ultraviolet-ray curable-adhesive 5 on the front side of the carrier stock; - (b) overlaying the front side of the carrier stock with the facestock; and (c) curing the adhesive with ultraviolet radiation through the reverse side of the carrier 10 stock.

   2. A method as claimed in Claim 1 in which both sides of the facestock and of the carrier stock are in a tack-free state upon the said ultraviolet 15 radiation curing.

   3. A method as claimed in Claim 1 or Claim 2 in which the adhesive is placed upon the carrier stock with a rotating roll.

   4. A method as claimed in Claim 1 or Claim 2 or Claim 3 in which the facestock is overlaid on the carrier stock between a pair of nip rolls.

   5_.

   A photoinitiatable adhesive, comprising: (a) a photoinitiator; (b) a polyurethane; (c) triacrylate; and (d) difunctional monomer.

   11.

   9 1 21 6. A photoinitiatable adhesive as claimed in Claim 5 which includes a blend of glycerol propoxytriacrylate and a microcrystalline wax grind.

   7. A photoinitiatable adhesive as claimed in Claim 5 or Claim 6 in which the difunctional monomer consists of or includes a caprolactone. - 8. A photoinitiatable adhesive that is curable to a tack-free state through a layer of a paper carrier stock, comprising: (a) 4-5%(wt.) of a photoinitiator; (b) 21-39%(wt.) polyurethane; (c) 10-20%(Wt.) glycerol propoxy triacrylate; and (d) 12- 32%(wt.) tripropylene glycol diacrylate.

   9. A photoinitiatable adhesive as claimed in Claim 8 which further includes a blend of 60%(wt.) glycerol propoxytriacrylate and 40%(wt.) microcrystalline.wax grind.

   1 0. A photoinitiatable adhesive, comprising 38.2 parts polyurethane, 9.5 parts acrylate ester, 17.2 parts glycerol propoxy triacrylate, 13.3 parts tripropylene glycol diacrylate, 13.3 parts caprolactone, 4.8 parts photoinitiator, and 3.7 parts of a blend of 60%(wt.) glycerol propoxytriacrylate and 40%(wt.) microcrystalline wax grind.

   Published 1988 a, The Patent Office, State House. 6671 Mgh Holborn, Lozdon WCJR 4TF. RL-Lher copies may be obtamed from The Patent =cc. Sales Branch. St. Mazy Cray., Orpingwri, Kent BR5 3RD. Printed by Multiplex technIques ltd. St. Mary Cray. Kent Con. 1/87.