CA1294382C

CA1294382C - Directly printable tape with novel release coating

Info

Publication number: CA1294382C
Application number: CA000497447A
Authority: CA
Inventors: Bernard S. Truskolaski; Daniel P. Pohl
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1985-01-23
Filing date: 1985-12-12
Publication date: 1992-01-14
Anticipated expiration: 2009-01-14
Also published as: BR8600227A; EP0475460A3; DE3686173D1; AU584656B2; NO855145L; NZ228621A; EP0475459A2; PH23463A; JPS61174285A; AR241166A2; ZA859623B; KR940000535B1; US4599260A; DE3686173T2; AU5133285A; AU3239089A; EP0189308A2; ATE78849T1; AR241166A1; NZ214917A

Abstract

ABSTRACT

This invention relates to directly printable tapes, inks for printing upon said tapes, and a method for printing upon said tapes.
Adhesive tapes with printed indicia on the back side, i.e., the side opposite that bearing adhesive are useful for advertising and identification functions. As a practical matter, the adhesive is generally a pressure sensitive adhesive. Inasmuch as pressure-sensitive adhesive tapes are those in Which the adhesive has sufficient adhesion and tack to adhere to adherend surfaces With light finger pressure, the tapes are generally coated`
on the back side With a release agent. Such a coating permits the tape to be unwound easily in roll form without transfer of the adhesive to the back side of the tape.
Thus, with printable pressure-sensitive adhesive tapes, the ink must adhere to the release coating, which is often called a "backsize", and not be removed by the adhesive in contact therewith.
This invention involves a directly printable tape comprising a polymeric film backing having a low adhesion backsize coating on one major surface thereof and a pressure-sensitive adhesive on the other major surface thereof. The low adhesion backsize coating comprises a mixture of a low adhesion backsize compound and an ink adhesion promoter. The disclosure further involves a method of printing on the low adhesion backsize coating and an ink composition. The ink comprises a conventional flexographic ink composition containing an ink adhesion promoter.

Description

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DIRECTLY PRINTABLE TAPE WIT_ NOVEL RELEASE COATING

BACKGROU~ID OF THE INV~NTION
This invention relates to directly printable tapes, inks for printing upon said tapes, and a method for printing upon said tapes.
Adhesive tapes with printed indicia on the back side, i.e., the side opposite that bearing adhesive are useful for advertising and identification functions. As a practical matter, the adhesive is generally a pressure-sensitive adhesive. Inasmuch as pressure-sensitive adhesive tapes are those in which the adhesive has sufficient adhesion and tack to adhere to adherend surfaces with light finger pressure, the tapes are generally coated on the back side with a release agent. Such a coating permits the tape to be unwound easily in roll form without transfer of the adhesive to the back side of the tape.
Thus, with printable pressure-sensitive adhesive tapes, the ink must adhere to the release coating, which is often called a "backsize", and not be removed by the adhesive in contact therewith.
Early attempts to provide printed pressure-sensitive adhesive tapes involved a process known as the "print seal processn. In this process, the back side of the tape is printed with indicia, dried, and immediately overprinted with a release agent and dried before the adhesive qurface contacts the printed indicia. Although this process produces a satisfactory tape when properly carried out, it requires a special printing machine with at least two printing and drying operations, making it inconvenient, expensive, and frequently variable in result.
A number of attempts have been made to provide printable, pressure-sensitive adhesive tapes which do not require overprinting. It has been particularly difficult 12~3'13~32 to find a release agent capable of sufficiently retaining the printed indicia against the adhesive action of high performance or high adhesion adhesives, especially those based on block copolymer elastomers. Thus, it is desirable to provide a release coating composition which when employed with such block copolymer-based pressure-sensitive adhesives will impart to tapes the property of ready release and good printability without advercely affecting adhesion and tack of the adhesive. It is further desirable to provide a release coating composition capable of forming a coating which is resistant to splitting and to loss of desirable properties on aging.
Current packaging tapes are required to achieve a level of performance which imposes drastic constraints on those tapes, which must of necessity be printable and carry a sharp, clear imprinted message from the tape roll to the surface upon which the tape is to be applied. Commercial distribution of printable packaging tapes requires that the tape be shipped to a converter who applies the printed indicia, in turn selling the printed tape in dispensable roll form ~o the ultimate customer. At this stage, the tape may be subjected to rea~onabl~ lengthy periods of storage at conventional warehou~ing conditions including moderately elevated temperatures. During this time, the highly aggre~sive pressure-sensitive adhesive i3 in direct contact with the underlying printed surface~ which may result in offsetting of the ink to the adhesive layer when the tape i~ ulti~ately dispen9ed from the roll.
The means for insuring sufficient anchorage of the printed matter to prevent this ink transfer, and the means for promoting satisfactory release of the adhesive layer from the backsize when the tape is in roll form are in essence diametrically opposed. Prior art attempts to balance these opposing forces have been accomplished only by cumbersome proces~ing steps which complicate the production of such tapes and increa~e the expense thereof.
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Attempts have also been macle to modify commercially available inks for use with low a~hesion backsize coated pressure-sensitive adhesive tapes by the addition of natural or synthetic waxy materials, but such attempts have been unsatisfactory because such additives tend to migrate into the adhesive layer and cause a variety of deficiencies such as detackification and loss in adhe-sive and cohesive strength.
SUMMARY OF TH~ INVENTION
In one aspect of this invention, there is provided a printable pressure-sensltive adhesive tape comprising backin~
film, -the faceside being coated Witll a pressure-sensitive adhesive and the backside being coated with a low adhesion backsize coating comprising (1) at least one low adhesion backsize compound, and (2) a chlorinated polyolefin in an amount sufficient to promote ink adhesion, said low adhesion bac'ksize coatin~ bears an inked impression and is low-force removable from said pressure-sensitive adhesive without transfer of said inked impression to said pressure-sensitive adhesive.
In another aspect, there is provided an ink capable of printing on the backsize coating of the previously described pressure-sensitive adhesive tape. This ink makes possible winding and unwinding the printed tape in normal fashion without transfer of ink from the printed surface to the adjacent pressure-sensitive adhesive. The ink comprises an ink composition comprising a resinous binder comprising a polyamide, a coloring agent, an effective amount of a chlorinated polyolefin, and a solvent, wherein said chlorinated polyolefin comprises from about 3 to ~4~82 about 12 weight percent of said composition. Preferably, the ink contains from about 15 to abou-t 35 weight percent, ana preferably from about 15 to about 30 weight percent of a resinous binder;
fro~ about 5 to about 15 weight percent, and preferably from about 6 to about 7 weight percent, of a coloring agent which can be inorganic or organic; from about 4 to about 7 weight percent, and preferably from about 4 to about 5 weight percent, oE a chlorin-ated polyolefin, and from about 55 to about 75 weight percent, and preferably from about 60 to about 70 weight percent, of a solvent for flexographic ink. Additional ingredients such as conventional ink modifiers can be added as necessary.
In a third aspeCt of thiS invention, there is provided a method for applying ink to the directly printable tape. This method involves heating the tape to a temperature sufficiently high to soften the low adhesion backsize coating, but not so high as to distort the polymeric backing or to degrade the adhesive, and applying ink to said backsize coating by means of a flexo-graphic printing apparatus while said coating is in a softened state.
The pressure-sensitive adhesive tape of this invention is directly printable. As used herein, the term "directly print-able" means capable o~ being printed on without the necessity ofrequiring any form of protective overcoating. It has overcome the objectionable tendency to transfer printed matter from "backside"
to "faceside", on unrollinq. The printed tape of this invention can function in a dual capacity as a packaging or holding tape as well as a printed identification or instructional message.

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- 4a - 60551-2987 For future reference and clarity in understanding this invention, the film ~acking of the tape of this invention has two principal surfaces. The surface bearing the pressure-sensitive adhesive is referred to as the "faceside", while the surface bear-ing the printing ink, which is the low adhesion backsize surface, is referred to as the "backside". The term "low adhesive backsize compound" refers to a compound or compounds that constitute an ingredient of the low adhesion backsize coating. The term "low adhesion backsize coating" refers to the layer that contains both the low adhesion backsize compound and the inX adhesion promoter.
DETAILED DESCRIPTION
Polymeric film backings suitable for the tape of the present invention i.nclude oriented and unoriented polymeric materials, such as, for example, polyolefins, e.g., polypropylene, polyesters, e.g., polyethylene 3~}Z

_5_ 557-2987 terephthalate, and polyvinyl chloride, e.g., unplasticized polyvinyl chloride. Although polypropylene bearing a low adhesion backsize coating generally presents difficult problems with respect to ink adhesion, the directly printable tape of the present invention can be made from a polypropylene backing with little difficulty. It is preferred that the polymeric film backing be oriented, either uniaxially or biaxially, because orientation conventionally provides increased strength to the tape. In the case of a packaging tapei biaxial orientation is preferred.
The present invention involves the proper selection of a binary component mixture to prepare a backsize coating which will allow direct printability and yet avoid the attendant problems previously noted. The first component of the mixture is at least one conventional low adhesion backsize compound, hereinafter alternatively re~erred to as an LAB. Representative examples of conventional low adhesion backsize compounds suitable for use in this invention are fully described in U.S. Patents 2,607,711, 2,532,011, and 3,318,85~.

For example, U.S. Patent 2,607,711 describes LAss formed of a copolymer of an ester of the class consisting o~ higher alkyl acrylates and methacrylates wherein the higher allcyl radical has a length of at least 12 carbon atoms, and an acid of the class consisting of acrylic acid and methacrylic acid. The acrylic acid or methacrylic acid can be replaced in part by another copolymerizable ethylenic monomer, e.g., acrylonitrile or methacrylonitrile.
U.S. Patent 3,318,852 describes LABs formed of a copolymer derived from an ethylenically unsaturated monomer containing a functional group forming a conjugated system with the ethylenic linkage wherein between about 10 and about 90 mole percent of the polymerized units of the copolymer contain a free carboxylic acid group as the .
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functional group forming the conjugated system and all other functional groups forming the conjugated system are hydrolyzable to a ~ree carboxyl acid group, and 20-90 percent by weight of monomeric units derived from an ethylenically unsaturated monomer containing a fluoroalkyl group of at least six carbon atoms. The solubility of the copolymer can be enhanced by the use o~ a third comonomer, also ethylenically unsaturated, containing a functional group which forms a conjugated system with its unsaturated bond and is hydrolyzable to a carboxyl group. Each of the monomers contributes to the overall properties of the copolymer.
U.S. Patent 2,532,011 describes LABs comprising polyvinyl carbamate polymers wherein the carbamate side chains terminate with an alkyl group more than five carbon atoms in length, and preferably at least 14. These can be made by reacting polyvinyl alcohol with an appropriate isocyanate having a terminal alkyl group. An example is polyvinyl N-octadecyl carbamate, made by reacting polyvinyl alcohol and octadecyl isocyanate~ which has 18 carbon atoms in the nitrogen-bonded side chain alkyl groups.
The ink adhesion promoter is ~elected from chlorinated polyolefins, e.g.~ chlorinated polyethylene, chlorinated polypropylene~ chlorinated polybutylene, and mixtures thereof.
Repre~entative exa~ples of commercially available chlorinated polyolefins include Eastman~ CP-343-1, available from Eastman Chemical Products, Inc., and "Hardlen" 13-LP, available from Toyo Kasei Kogyo Co., Ltd.
The low adhesion backsize coating should contain at least about 10 percent by weight, and preferably from about 80 to about 90 percent by weight, of low adhesion backsize compound. This amount insures reasonableness in terms of the unwind force of the pressure~sensitive adhesive tape. The backsize coating sho~ld contain at least about 0.25 percent by weight chlorinated polyolefin, and preferably from about 10 to about 20 percent by weight.

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~7~ 557-2987 The amount of chlorinated polyolefin required to insure adequate ink adhesion depends on several factors, including the nature of the polymeric film backing, the nature of the adhesive, usage and storage conditions.
The coating thickness and weight of the low adhesion backsize coating are substantially the same as those described in U.S. Patent 2,532,011. For example, the low adhesion backsize coating can be very thin, e.g. less than one-hundred-thousand of an inch thick, constituting a ~ 10 "molecular film" (i.e. a film which has a thickness of only a relatively few molecules). It has been found that coating weights of from about 0.2 to about 1.0 lb. per 1000 square yards of polymeric film backing give the results desired. Thicker coatings can be used if so desired.
Conventional pressure-sensitive adhesives can be used in the tape of this invention. A representative example of a suitable adhesive is described in U.S. Patent 3,239,478.
The two components of the low adhesion backsize coating are typically combined in solution form. The resultant mixture is adjusted to a solids percentage depending on the particular coating method employed. The - preferred solvents are toluene and xylene.
Either the low adhesion backsize com~ound solution or the chlorinated polyolefin solution can be charged to a mixing vessel and the other solution and any additional solvent can then be added to complete the blend.
To insure homogeneity, the blend typically requires agitation prior to coating, in conventional fashion.
The backsize coating solutions described in this invention are generally coated onto the backside of the polymeric film backing prior to the coating of the pressure-sensitive adhesive to the faceside thereof. A
conventional rotogravure roll coater can be used, which accurately meters the quantity of coa~ing solution applied, and insures a uniform and continuous coating.

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An ink found useful for printing on the backside of the tape of the present invention comprises a mixture of a conventional flexographic ink stock and a chlorinated polyolefin. The flexographic ink stock in general comprises colorin~ agents and liquid vehicles ~omprising solutions of suitable binders in solvents. A specific choice of binders and solvents depends on seve~al factors, such as, for example, the nature of the coloring agents.
The essence of the ink of this invention co~nprises incorporating a chlorinated polyolefin into such conventional inks. Suitable chlorinated polyolefins can be ~elected from the same group that are suitahle as the ink adhesion promoter in the low adhesion backsize coating previou~ly described. Examples of suitable commercially available chlorinated polyolefins include Eastman~ CP-343-1 and "Hardlen" 13-LP.
Solvent systems commonly employed in the manufacture of flexographic inks are the lower aliphatic alcohols, includlng propanol, isopropanol, ethanol and butanol, the lower aliphatic e~ter~, in particular ethyl acetate; and the lower aliphatic ketones, in particular methl ethyl ketone. Additional solvent ~ystems for flexographic inks are described in Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed. Vol. 13, John Wiley & Sons, Inc. (New York: 1981), p. 387. The amount and type of ~olvent are regulated ~o a~ to give the ink the desired drying speed and degree of penetration.
Binders for ink vehicles are commonly selected from rosin esters~ synthetic film-forming polymers~
polyamides~ alkyd resins and proteins~ including casein, gelatin and soy protein. The choice of binder depends upon the particular ~ubstrate used, each type of fibrous or film material having specific requirements for optimum adhesion~
a is known to those of ordinary skill in the art.
Coloring agents can be organic or inorganic.
Representative examples inolude dyes and pigments. The ~ 2~3~Z

choice of suitable coloring agents is known to those of ordinary skill in the art.
In addition to the above-~entioned chief components, conventional flexographic inks customarily contain various amounts of modifying agents selected frorn waxes such as beeswax or paraffin wax, drying oils such a~
linseed oil, caster oil, turpentine oil, menhaden oil or the salts of linoleic acid, oleostearic acid and the like with amines such as triethanolamine or hydroxypropylamine, as well as sma'l quantities of so-called drier like cobalt resinate, cobalt linoleate, or an aluminum soap of linseed or tung oil. The use of such modifying agents is a well-established art.
An effective amount of chlorinated polyolefin must be added to the ink composition to promote ink - adhesion. An effective amount is generally at least about 0.25 weight percent of thè ink composition. If too great a concentration of chlorinated polyolefin is incorporated in the ink, e.g. greater than 12 weight percent, the adhesive may pick off the backsize coating or adhesive may be transferred to the printed surface.
Preferably, the concentration of ingredients o the ink composition is as follows:
Amount Preferred amount 25 In~redient(Percent by weight? (Percent by weight) Coloring agentabout 5 to about 15 about 6 to about 7 Resinous binderabout 15 to about 35 about 15 to about 30 Solventabout 55 to about 75 about 60 to about 7Q
Chlorinated polyolefinabout 3 to about 12 about 4 to about 5 The concentrations of coloring agent, resinous binder, and solvent can vary from the foregoing concentrations.

lZ9~t32 Other inks found suitable for printing on the backside of the tape of the present invention are described in assignee's copending Canadian patent application No. 491,181 filed on December 9, 1985. An exemplary ink composition, described in the above-referenced Canadian patent application contains the following ingredients in the amounts indicated (the percentages are percentages by weight):
Amount Amount Ingredient (% of dry solids) (% of total) Dry solids: 41.6 Binder (mixture of poly- 48.9 amide and nitrocellulose) Pigment 19.0 Chlorinated polyolefin 15.4 (Eastman ~ CP 343-1) Wax 1.3 Fatty acid amide (Armid~ HT, 15.4 available from Armak Company) Solvent (mixture of methanol, 58.4 ethanol, isopropanol, n-propanol, ethyl acetate, n-propyl acetate) 10 One ink preferred contains per 100 weight percent of total composition: from about 10 to about 25 weight percent, and preferably from about 20 to about 25 weight percent, of a resinous binder; from about 3 to about 10 weight percent, and preferably from about 4 to about 6 weight percent, of a coloring agent which can be inorganic or organic; from about 1 to about 5 weight percent, and preferably from about 2 to about 3.5 weight percent, of a low adhesion backsize compound, and from about 40 to about 80 weight percent, and preferably from about 50 to about 70 weight percent, of a conventional solvent for flexographic ink. In ., .

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another embodiment of such an ink an effective amount of chlorin-ated polyolefin, e.g., from about 3 to about 12 weight percent, preferably from about 4 to about 6 weight percent chlorinated polyolefin, can also be added to the ink. Additional ingredients such as conventional ink modifiers can also be added. Low adhesion backsize compounds that can be used in the aforementioned ink are fully described in U.S. Patents 2,607,711, 2,532,~11 and 3,318,852.
A sufficient amount of low adhesion backsize compound must be incorporated in the ink stock composition to prevent ink pick-off by aggressive adhesives, such as for example, those adhesives descri~ed in U.S. Patent 3,239,478, without adversely affecting the functional properties of the adhesive. Concentra-tions of low adhesion backsize greater than about 5 percent by weight are not preferred because most low adhesion backsize compounds are not readily soluble in conventional flexographic solvents. The addition of a chlorinated polyolefin t~ the ink provides an improvement with respect to ink anchorage. Chlorin-ated polyolefins that are suitable for the ink are the same as those that are useful for the tape.
When a mixture of additives is used, i.e., when both the low adhesion backsize compound and the chlorinated polyolefin are used, the individual additives can be added separately to the conventional ink stock composition, or, when convenient, said components can be mixed together before being added to the ink stock composition.
The solvent systems commonly employed in the manufacture of flexographic inks and the binders for ink vehicles that were described earlier are also suitable for the ink compositions that contain low adhesion backsize compounds.

Coloring agents can be organic or inorganic.
Representative examples of coloring agents include dyes and pigments. The choice of suitable coloring agents is known to those of ordinary skill in the art.
In addition to the above-mentioned chief components, conventional modifying agents as described previously can also be incorporated into the low adhesion backsize compound-containing ink composition.
The third aspect involves the method of printing on the novel tape of this invention with the aforementioned inks.
The tape is subjected to a temperature sufficiently high to soften the low adhesion backsize coating, but not so high as to distort the polymeric backing or to degrade the adhesive. The ink is applied to the low adhesion backsize coating when it has reached this softened state. As used herein, the term "soften", "softened state", and the like refers to the condition of a solid that has reached its softening point, which point is defined as the temperature at which a solid flows (see Concise Chemical and Technical Dictionary, 3rd ed., Chemical Publishing Company, Inc. ~New York: 1974), p. 961).
After the tape has been printed, it can be used immediately or rewound and stored for use at a later date.
Rewinding of the printed tape is conducted under conventional conditions well known to those of ordinary skill in the art.
In the directly printable tapes of this invention, the printed ink remains anchored to the tape backside while the pressure-sensitive adhesive releases from the printed surface easily without "picking" or transferring of the printed matter to the pressure-sensitive adhesive, or transferring of the adhesive to the printed matter. Such can be accomplished without additional post printing treatment such as heat, pressure, , .

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radiation, or additional overcoating of a release-promoting layer.

Exam~le 1 A gravure roller consisting of a 200 line pyramidally knurled roll was utili~ed to apply the low adhesion backsize coatin~s at a machine speed of 20 yards/minute using solutions having a solids content of 5.8 percent. The coatings were then dried in an oven at 150F
for 1.5 minutes prior to winding the coated film in roll for~.
These coating conditions resulted in backsize coatings which ranged in thickness from about 200 to about 800 nanometers.
The polymeric film backing utilized was corona treated biaxially oriented polypropylene. Film thicknesses ranged from 1 to 2 mils. The faceside of each film was then coated with a pres~ure-sensitiVe adhesive~ a ~onventional block copolymer 5yStem ~imilar to those described in U.S.
Patent 3~239/478. The pre9sure-9en~itive adhesive was applied at coating weights of 17 to 30 gramS per Sq~are ~eter.
The completed pressure-sensitive adhesive tape wa9 in the form of a 12 inch wide roll which was slit to rolls of 2 inch width and 60 yard length for evaluation and testi ng .

Ink Removal Tests A conventional flexographic printer, the SIAT L3 Printer, commercially available from Flexo Printing Equipment Corp., was used to print the backside of the test tape rolls. The ink~ utilized in the test procedure were "Flexotuf" Hard Blue 84Lo569 or "Flexotuf" Hard slack 84L0863, available from the Inmont Corporation, modified by the addition of Eastman~ CP 343-1 chlorinated polyolefin and ~rmidv HT fatty acid amide. The ink is fully described in Canadian patent application No. 497~181 filed on December 9, 1985.

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Printing was carried out at a machine speed of 100 yards/minute. The printed indicia covered 30 to 40 percent of the area of the tape backside. The tape was heated to approximately 200F, at which temperature the low adhesion back~ize coating was softened, and the ink was applied. Following printing, the tape was rewound in roll form for storage. The thus printed rolls were then aged at 120F for eleven days. The rolls of tape were unwound by hand at a rate consistent with nor~al tape application procedure~. The quantity of ink removed was determined subjectively by visual observation, and tapes exhibiting no more than about 5 percent ink removal by this test were considered acceptable.

Unwind And Adhesion Tests of Printed Tape Unwind forces were measured as the tape roll was unwound after printing. The adhesion test was performed by applying a length of the tape to a polished steel surface followed by removal therefrom.
Both of these tests are described in detail in the Seventh Edition of "Test Method For Pressure Sensitive Tapes", copyright 1976, Pressure Sensitive Tape Council, Glenview, Illinois. The test for unwind force i9 designated PSTC-8, while the adhesion test is de~ignated PSTC-l.
It is preferred for commercial purposes that unwind be 25 oz/in or lower. It is preferred that adhesion drop be 1~% or lower.
Backsize coating composition A containin~ the components set forth in Table I was prepared in the following manner. The LAB (19.2 g) was dissolved in xylene (364.6 g) and the chlorinated polyolefin (4~0 g) was dissolved in toluene (12.0 g). The LAB solution was charged to a one-quart jar, and then the chlorinated polyolefin solution was charged. The blend was stirred to bring about homogeneity. Backsize coating compositions B-F
were prepared in the same manner as backsize Coating composition A, the only exceptions being the relative 1;2~?~3~3~

amounts of chlorinated polyolefin and LAB present in the coating solutions. Backsize coating composition G did not contain a chlorinated polyolefin. The compositions were applied to films as set forth in Table II according to the general coating procedure previously described and the coated film dried at a temperature of 150F.

TAsL~ I

sacksize coating composition (parts by weight, dry solids) 10 Components _ B C D E FG_ _ _ _ _ Chlorinated5 10 15 17 40 56 0 polyolef inl 1 Eastman CP 343-1 2 Polyvinyl N-octadecyl carbamate as described in U.S.
Patent 2,532,011.

The opposite surface of the film was coated with the adhesive previously described.
The tapes were slit to about two inches in width and printed in the manner previously described. The printed tapes were wound into rolls and some were retained for 11 days at 120F. The tapes were measured for adhesion, unwind force, and observed for ink transfer, with the results shown in Table II.

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1~9~3~2 The data in the foregoing table show that tape havin~ a low adhesion backsize coating wherein the concentration of chlorinated polyolefin ranges from 5 percent by weight to 17 percent by weight provides good unwind and ink transfer properties, while not adversely affecting adhesion properties to an unacceptable extent.
The identical release compositions and adhesives used in Example 1 can be applied to a biaxially oriented polyethylene terephthalate backing (thickness of 1 to 2 mils) in the manner described in Example 1. Upon being tested under the same conditions as in Example 1, the results will be substantially similar to those of Example 1~

Example 2 An ink composition was prepared by adding 1.19 grams of chlorinated polyolefin (Eastman~ CP 343-1) to 20.0 grams of Rotoflo OPQ Red B758700 75Lo555 a commercially available flexographic ink composition manufactured by Inmont Corporation.
This ink wa~ u~ed to print on the same types of tape as described in Example 1 under the same printing condition~ as described in Example 1. Upon being tested under the same conditions as in Example 1, the results were substantially similar to those of Example 1.

Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the embodiments set forth herein.

Claims

1. A printable pressure-sensitive adhesive tape comprising backing film, the faceside being coated with a pressure-sensitive adhesive and the backside being coated with a low adhesion back-size coating comprising (1) at least one low adhesion backsize compound, and (2) a chlorinated polyolefin in an amount sufficient to promote ink adhesion, said low adhesion backsize coating bears an inked impression and is low-force removable from said pressure-sensitive adhesive with-out transfer of said inked impression to said pressure-sensitive adhesive.

2. The tape of claim 1 wherein said chlorinated polyolefin comprises at least about 0.25 percent by weight of said low adhesion backsize coating.

3. The tape of claim 1 wherein said chlorinated polyolefin comprises from about 10 percent by weight to about 20 percent by weight of said low adhesion backsize coating.

4. The tape of claim 1 wherein said low adhesion backsize coating contains at least 10 percent by weight of low adhesion backsize compound.

5. The tape of claim 1 wherein said low adhesion backsize coating contains from about 80 to about 90 percent by weight of low adhesion backsize compound.

6. The tape of claim 1 wherein said low adhesion backsize compound is selected from the group consisting of polyvinyl carbamate polymers wherein the carbamate side chains terminate with an alkyl group more than five carbon atoms in length, copolymers of an ester of the class consisting of higher alkyl acrylates and methacrylates wherein the higher alkyl radical has a length of at least 12 carbon atoms, and an ethylenically unsaturated monomer, copolymers derived from an ethylenically unsaturated monomer containing a functional group forming a conjugated system with the ethylenic linkage wherein between about 10 and about 90 mole percent of the polymerized units of the copolymer contain a free carboxylic acid group as the functional group forming the conjugated system and all other functional groups forming the conjugated system are hydrolyzable to a free carboxyl acid group, and 20-90 percent by weight of monomeric units derived from an ethylenically unsaturated monomer containing a fluoroalkyl group of at least 6 carbon atoms.

7. The tape of claim 1 wherein said film backing is biaxially oriented.

8. The tape of claim 7 wherein said backing is selected from polyolefins, polyesters, polyvinyl chlorides.

9. The tape of claim 8 wherein said backing is selected from polypropylene and polyethylene terephthalate.

10. The tape of claim 1 wherein said film backing is uniaxially oriented.

11. The tape of claim 10 wherein said backing is selected from polyolefins, polyesters, and polyvinyl chlorides.

12. The tape of claim 11 wherein said backing is selected from polyproplene and polyethylene terephthalate.

13. A printed pressure-sensitive adhesive tape comprising a backing film, the faceside thereof being coated with a pressure-sensitive adhesive and the backside thereof being coated with a low adhesion backsize coating comprising (1) at least one low adhesion backsize compound, and (2) a chlorinated polyolefin in an amount sufficient to promote ink adhesion, wherein said low adhesion backsize coating bears an inked impression and is low-force removable from said pressure-sensitive adhesive without transfer of said inked impression to said pressure-sensitive adhesive.

14. The tape of claim 13 wherein said chlorinated polyolefin comprises at least about 0.25 percent by weight of said low adhesion backsize coating.

15. The tape of claim 13 wherein said chlorinated polyolefin comprises from about 10 percent by weight to about 20 percent by weight of said low adhesion backsize coating.

16. The tape of claim 13 wherein said low adhesion backsize coating contains at least 10 percent by weight of low adhesion backsize compound.

17. The tape of claim 13 wherein said low adhesion backsize coating contains from about 80 to about 90 percent by weight of low adhesion backsize compound.

18. The tape of claim 13 wherein the low adhesion backsize compound is selected from the group consisting of polyvinyl carbamate polymers wherein the carbamate side chains terminate with an alkyl group more than five carbon atoms in length, copolymers of an ester of the class consisting of higher alkyl acrylates and methacrylates wherein the higher alkyl radical has a length of at least 12 carbon atoms, and ethylenically unsaturated monomer, copolymers derived from an ethylenically unsaturated monomer containing a functional group forming a conjugated system with the ethylenic linkage wherein between about 10 and about 90 mole percent of the polymerized units of the copolymer contain a free carboxylic acid group as the functional group forming the conjugated system and all other functional groups forming the conjugated system are hydrolyzable to a free carboxyl acid group, and 20-90 percent by weight of monomeric units derived from an ethylenically unsaturated monomer containing a fluoroalkyl group of at least 6 carbon atoms.

19. The tape of claim 13 wherein said film backing is oriented.

20. The tape of claim 19 wherein said backing is selected from polyolefins, polyesters, polyvinyl chlorides.

21. The tape of claim 20 wherein said backing is selected from polypropylene and polyethylene terephthalate.

22. An ink composition comprising a resinous binder compris-ing a polyamide, a coloring agent, an effective amount of a chlorinated polyolefin, and a solvent, wherein said chlorinated polyolefin comprises from about 3 to about 12 weight percent of said composition.

23. The composition of claim 22 wherein said chlorinated polyolefin comprises from about 4 to about 7 weight percent of said composition.

24. The composition of claim 22 wherein said resinous binder comprises about 15 to about 35 weight percent of said composition, said coloring agent comprises from about 5 to about 15 weight percent of said composition, said chlorinated polyolefin comprises from about 3 to about 12 weight percent of said composition, and said solvent comprises from about 55 to about 75 weight percent of said composition.

25. The composition of claim 22 wherein said resinous binder comprises from about 15 to about 30 weight percent of said com-position, said coloring agent comprises from about 6 to about 7 weight percent of said composition, said chlorinated polyolefin comprises from about 4 to about 5 weight percent of said composi-tion, and said solvent comprises from about 60 to about 70 weight percent of said composition.

26. A method of printing a printable pressure-sensitive adhesive tape, which tape comprises a polymeric film backing coated on the faceside thereof with a pressure-sensitive adhesive and coated on the backside thereof with a low adhesion backsize coating, comprising the steps of (1) heating the tape to a temperature sufficiently high to soften the low adhesion backsize coating, but not so high as to distort the polymeric backing or to degrade the adhesive, and (2) applying ink to said backsize coating by means of a flexographic printing apparatus while said coating is in a softened state.

27. The method of claim 26 wherein the printable pressure-sensitive adhesive tape comprises a backing film having a faceside and a backside, the faceside thereof being coated with a pressure-sensitive adhesive and the backside thereof being coated with a low adhesion backsize coating comprising (1) at least one low adhesion backsize compound, and (2) a chlorinated polyolefin in an amount sufficient to promote ink adhesion, said low adhesion backsize coating being ink-imprintable and low-force removable from said pressure-sensitive adhesive.