Water-dispersible pressure-sensitive adhesive and tape made therewith

Abstract

Repulpable splicing tape, especially adapted for splicing carbonless paper. The preferred adhesive is a blend of acrylate:acrylic acid copolymer, NaOH and/or LiOH KOH, and certain ethoxylated plasticizing components. A small amount of polyamide-epichlorohydrin crosslinker may also be included.

I claim: 
     
       1. Normally tacky and pressure-sensitive water-dispersible adhesive especially suitable for splicing carbonless paper, comprising the blended reaction product of (a) 100 parts by weight of a copolymer of monomers consisting essentially of (1) about 60-85 weight percent of at least one monomeric acrylic acid ester of nontertiary alkyl alcohol having 4-14 carbon atoms, and, correspondingly,   (2) about 40-15 weight percent of vinyl carboxylic acid,     (b) about 50 to 250 parts by weight of ethoxylated plasticizing components, sufficient to impart adhesion values such as to cause the adhesive to delaminate kraft paper when tested as described herein, consisting essentially of at least one of the following: (1) up to about 125 parts by weight, but not so much as to cause adhesive separation, of one or more OH-functional ethoxylated plasticizers and   (2) one or more electrolyte-tolerant complex acidic esters of phosphoric acid and an ethoxylated nonionic surfactant, and     (c) alkaline hydroxide consisting essentially of (1) sodium hydroxide, lithium hydroxide, or both sodium hydroxide and lithium hydroxide, in an amount sufficient to enhance shear strength and minimize bleeding but insufficient to cause separation of any OH-functional ethoxylated plasticizer present, not exceeding about 0.07 hydroxyl equivalent if OH-functional ethoxylated plasticizer is the only plasticizing component present, and   (2) potassium hydroxide in an amount sufficient to promote water solubility.     
     
     
       2. The adhesive of claim 1 wherein the total amount of sodium hydroxide and lithium hydroxide provides from about 0.02 to about 0.2 hydroxyl equivalent and the potassium hydroxide provides from about 0.1 to about 0.6 hydroxyl equivalent. 
     
     
       3. The adhesive of claim 1 wherein the blended reaction product consists essentially of (a) 100 parts by weight of a copolymer of monomers consisting essentially of (1) about 60-85 weight percent of at least one monomeric acrylic acid ester of nontertiary alkyl alcohol having 4-14 carbon atoms, and, correspondingly,   (2) about 40-15 weight percent of vinyl carboxylic acid,     (b) about 100 to 250 parts by weight of plasticizing components, of which (1) at least about 50 parts by weight are one or more acidic esters of phosphoric acid and ethoxylated alcohol or phenol derivative and   (2) any balance is made up of one or more ethoxylated diamines or ethoxylated phenols, and     (c) sufficient sodium hydroxide to neutralize at least about 5% of the copolymer acid function.   
     
     
       4. The adhesive of claim 3 wherein the acrylic acid ester comprises butyl acrylate and the vinyl carboxylic acid comprises acrylic acid. 
     
     
       5. Normally tacky and pressure-senstive adhesive tape comprising a layer of the adhesive of claim 3 coated on a sheet backing. 
     
     
       6. The tape of claim 5 wherein a tackifying rosin or rosin derivative is included in the adhesive. 
     
     
       7. The tape of claim 5 wherein an extremely small amount of polyamide-epichlorohydrin crosslinking resin is included in the adhesive. 
     
     
       8. The tape of claim 5 wherein the adhesive consists essentially of 100 parts of a butyl acrylate: acrylic acid copolymer having a COOH equivalent in the approximate range of 0.25 to 0.45, sufficient NaOH to provide approximately 0.02-0.2 OH equivalent, sufficient KOH to provide approximately 0.1-0.6 OH equivalent, about 50-250 parts of plasticizer, and 0.08-0.50% by weight polyamide-epichlorohydrin resin crosslinker based on total adhesive solids. 
     
     
       9. The adhesive of claim 1 wherein the plasticizing components include both OH-functional ethoxylated plasticizer and acidic ester of phosphoric acid and ethoxylated alcohol or phenol derivative. 
     
     
       10. The adhesive of claim 9 wherein about 50 to 100 parts by weight of oily ethoxylated plasticizer are present. 
     
     
       11. The adhesive of claim 10 wherein about 50 to 100 parts by weight of the phosphoric acid ester are present. 
     
     
       12. The adhesive of claim 11 wherein from about 75 to about 150 parts by weight of rosin or rosin derivative are present. 
     
     
       13. Normally tacky and pressure-sensitive adhesive tape comprising a layer of the adhesive of claim 12 coated on a sheet backing. 
     
     
       14. The tape of claim 13 wherein an extremely small amount of polyamide-epichlorohydrin resin crosslinker is included in the adhesive.