CA2122921A1 - Uv-cured hot melt pressure-sensitive adhesives - Google Patents
Uv-cured hot melt pressure-sensitive adhesivesInfo
- Publication number
- CA2122921A1 CA2122921A1 CA002122921A CA2122921A CA2122921A1 CA 2122921 A1 CA2122921 A1 CA 2122921A1 CA 002122921 A CA002122921 A CA 002122921A CA 2122921 A CA2122921 A CA 2122921A CA 2122921 A1 CA2122921 A1 CA 2122921A1
- Authority
- CA
- Canada
- Prior art keywords
- monomer
- pressure
- temperature
- polymer
- monomers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
- C09J133/04—Homopolymers or copolymers of esters
- C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09J133/08—Homopolymers or copolymers of acrylic acid esters
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/10—Esters
- C08F220/12—Esters of monohydric alcohols or phenols
- C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
- C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
- C08F220/1808—C8-(meth)acrylate, e.g. isooctyl (meth)acrylate or 2-ethylhexyl (meth)acrylate
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F246/00—Copolymers in which the nature of only the monomers in minority is defined
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J2301/00—Additional features of adhesives in the form of films or foils
- C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
- C09J2301/302—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
Abstract
The present invention relates to a pressure-sensitive-adhesive copolymer comprising copolymerizable photoinitiator monomers such as benzoin compounds, acyloin compounds, and mixtures thereof;
low-glass-transition-temperature monomers; and multifunctional monomers. The invention also provides a process for the preparation of such copolymers. The actinic radiation cure of the polymer is performed with light at about 240 to about 410 nm wavelength, a light intensity of about 6 to about 10 kWatts/m2, and at a temperature of about 45 ·C to about 125 ·C, under aerobic conditions.
The resultant pressure-sensitive adhesives exhibit cohesive strength and high-temperature shear strength which, in a static shear test, does not fail after several thousand minutes; a tack performance of about 300 to about 500 N/m; a peel adhesion performance of about 550 to about 650 N/m; a shelf-life at room temperature of more than about 10 months, with little or substantially no increase in the viscosity of the polymer; and a hot melt pot-life at 100 ·C of at least 10 days, with little increase in the viscosity of the polymer.
low-glass-transition-temperature monomers; and multifunctional monomers. The invention also provides a process for the preparation of such copolymers. The actinic radiation cure of the polymer is performed with light at about 240 to about 410 nm wavelength, a light intensity of about 6 to about 10 kWatts/m2, and at a temperature of about 45 ·C to about 125 ·C, under aerobic conditions.
The resultant pressure-sensitive adhesives exhibit cohesive strength and high-temperature shear strength which, in a static shear test, does not fail after several thousand minutes; a tack performance of about 300 to about 500 N/m; a peel adhesion performance of about 550 to about 650 N/m; a shelf-life at room temperature of more than about 10 months, with little or substantially no increase in the viscosity of the polymer; and a hot melt pot-life at 100 ·C of at least 10 days, with little increase in the viscosity of the polymer.
Description
w~ /n~ IPC~/U$~2/09~g~
2122g2~ ' ,'~'' W -CURED HOT MELT PRESSURE-SENSITIVE ADHESIVES
Field of_the Invention This invention is related to photo-curable, pressure~~ensitive adhesives.
Backqround of the Invention High-performance pressure~-sensitive adhesives (PSAs) are normally characterized by the ability of the adhesive to withstand creep or shear deformation ~0 at high loadings and/or high temperatures while exhibiting adequate tac;~ and peel adheslon proper~
ties.
This balance of prope~ties is derived from the polymer structure of the PSA~ ~Such p~olymers are c~aracterized by a high~-molecular weight to provide the necess~ry resi~t~nce to she r deformatlon a~d by~
a low modulus of elasticity of the polymer ba~kbone t~ allow th~ polymer to conf~orm to a ~ubstrate surf~ce upon contact.~ ~:Certain~ surfa~e~energy and 3Q pularity requirements must::~also~ be satisfied for a ! go~d bond to form between: the~adhesive~: andl the substr~te.
The desired high molecu~lar~ weights~can::: be obtained either by primary~polymeri~zatlon of monomers t~ ~orm long-chain-length:backbon~s, or by crosslink~
ing of pre-existing~primary~polym~r:chains.
WV~ X2 2 1 2 ~ ~ 7 ~ PC~/USg~0~4s3 1 The PSA polymer backbone should consist of material of low enough modulus or high enough compli-ance to make a good contact with the adherent at the application temperature. This condition is normally satisfied by the use of material of low glass-transi-tion temperatures (Tg's), such as polymers or c~poly-mers of 2-ethyl-hexylacrylate, iso-octylacrylate, butylacrylate, ethylacrylate, methylacrylate, or the like.
Frequently, small amounts of other types of monomers are incorporated to modify the polarity, the rheological and surface properties of the polymer, such as acrylic aci~, maleic acid, ~-carboxyethylacr-ylate, esters of methacrylic acid, laurylacrylate, stearylacrylate, styrene, dibutylfumarate, dioctylma~eate, dioctylfumarate, vinylacetate, or the like.
Resistance to creep or shlear deformation in a high-performance PSA is normally the result of a hig~
internal cohesive strsngth. This condition can usually be obtained from a high primary polymer molecular weight. However, if the internal cohesive strength imparted by the polymer is insu~ficient, high in~ernal cohesive strength can also be obtained by incor~orating, into the polymer body, a high degree of interchain hydrogen bonding, ionic associa~
tion, or covalent crasslinking.
With hot melt PSAs, crossli~king the adhesive ~y radiation after~ coating is~ one of the~preferred 3Q methods of incorporating~high Gohesive streng~ih. The ! conv~rsivn of a f~uid whIch flows and ~oats~out ~ell,~
into a non-flowing ~is:coelastic material can be done with better con~rol by radiati~n crosslinking than by thermochemical mean:s.
In order for:a:polymer ~o be~crosslinkable:by W
radiation, the polymer~ ne~s to carry ~in~
unsaturation which,:in~the pre~eoce of~small amounts .. .. .. .
. . ;. - , WU~ 2 212~21 PCT/US~2/~9493 1 of added multi-vinyl-functional monomers and a photoinitiat~r, would resp~nd to vinyl addition polymerization upon W radiation. The combination of vinyl unsaturation on the polymer and multi-vinyl-functional monomers leads to very poor melt potliYes; polymer gelation in only an hour at the melt temperature is not uncommon with hot melt PSA formu-la~ions.
Crosslinking by W radiation of a polymer without vinyl unsaturation is also possible when a peroxy compound is present in addition to the multi~
vinyl~functional mo~omer and photoinitiator. Peroxy compounds which have been used are benzoylperoxide and t-butylperbenzoate. However, once again, the pot lives of the unfunctionali~ed hot melt polymer in the presence of the peroxy compound and multi-vinyl-functional monomers are very short, i.e., of the order of an hour at the melt te!mperature.
U.S. Patent No. 4,~181,752 cliscloses the manufac-~0 ture of P~As in web polymeriæativn of a polymer-monomer syrup by W irradiation. To form polymer molecules of sufficiently ~igh molecular weights, the UV energy o~ 300 and 400 nm wavelength is supplied at low intensities, 0.~01 to 0.07~ kWatts/m2 while maintaining the web temperature below 35C. In an on-web-syrup polymerization, the low W :.intensity r~quirement necessitates that cure takes place at relatively low web speeds of about 2 inches per minute to 2 feet per minute. Howev r, this irradia~
tion is preferably carried out under anaerobic conditions thus requiring ~n a~mosphere co~trol sy~tem.
U.S. Patent No. 4,052,527, discloses a method of production of UV crosslinkable ho~ melt pressure~
sen itive adhesives which cont~in~photoi:nitiators of the 3-(chlorinated aryloxy~2-hydroxypropyl acrylates or methacryl~tesO The photoinitiators were copoly-. ~ ~
wn ~ 91S~ ~ 12 ~ .~) 2 1. P~r/US~2/l~4~?~
1 merized into acrylic polymers and which containedother modifying monomers su~h as vinylics, and were made in solution, emulsion, or in bulk~ When not made in bulk, the solvent medium is vacuum-stripped so that the polymer can be coated as a melt between 120C and 180C. W cure is obtained from commercial medium-pressure lamps of 200 Wa~ts per inch intensi-ty. However, multiple passes under the W lamp are required to obtain moderate increases in shear strengths, 2.g., improvement of room-temperature shears from 4 minutes before W cure to only 0.5 hour shear after. passing 15 times under the W lamp, 1.5 hour shear after 2S passes, and 3.5 hours shear after 35 passes under the W lamp.
U.S. Patent No. 4,144,157 and DE 27-43-979 dis~loses the W crvsslinkability of acrylic pres-sure-sensitive adhesives which were exemplified by polymers which are made in and coated out of solu-tion, or when made in bulk are to be coated out of solution. The pressure-sensitive-adhesi~e materials are W -cross linkable to high shear strengths, because of copolymerizable photoinitiators in the pressure-sensitive adhesive polymer which belong to a class of (2-alkoxy,2-phenyl-2-benzoyl)ethyl 2 acrylates or methacrylates and the acrylate or methacrylate of benzoin or its derivati~e. The W
cure is obtained by radiation from high-p~essure mercury lamps or burners, with very-high-intensity ~utputs of from one lamp af ~00 Watts to four lamps of 2000 Watts each. ~espite the use of high-intensi-ty, high-pressure mercury lamps, the pressure-sensi~
~ive-adhesive material needs relatlvely high W
dosages of at least about 10 kJ/m2 before hig~ shear strengths can be obtained in the adhesive. The 3~ ad~ixkure of reactive cr~sslinking agents such as multiIunc~ion~l acrylic monomers to the pres~ure sensiti~e-adhesive material prio~ to coating and W
,, ~
" ' `' '.
. '.,~:~,'', . ;....
:, :` ;' W~ tl)~l~' 212 ~ 9 2 1 PCr/US~2/~4~3 1 cure is explicitly discouraged to prevent poor shelf stability of the coater-ready material.
U.S. Patent No. 4,~81,152 describes the synthe-sis of benzophenone derivatives which are copolymeri-za~le into a polymer backbone by way of acrylicfunctiona~ groups. The benzophenone derivatives are useful as a component in W -curable resin composi-tions and in anaerobic thermosetting adhesive compo-sitions.
U.S. Patent NQ~ 4, 672, 079 describes a method of manufao~uring polystyrene derivatives with W -activatable ~unctional groups, and the use of these compounds in the photopolymerization of monomer or oligomer mixture~ with ethylenic unsaturation for use in wood paints, paper lacquers, printing inks, engraving printed and integrated circuits, fabric printing, and the like, but not for pressure-sensi-tive adhesives.
European Patent Application ND. 87-30439~.2 and U.S. Patent No. 4,737,559 describe the synthesis and the use of benzophenone and acetophenone photo~
initiator derivatives, which are coplymerizable into a copolymer backbone by acrylic or acrylamide func-tional groups for use in adhesive compositions for human skin contact application. A pressure-sensitive adhesive is described which is a copolyme~ of acrylic monomers and the ketone deriv~tive, by means of which the copolymer can be UV~crosslinked. The amount of crosslinking ketone ~omonomer and the degree of polymerization of the copolymer are controlled, to obtain the right creep compliance ~alue for an~
enhanced leveil of initihl adhesion when applied to the skin, but r 5iSt objec~ionable adhesion build-up ovèr time.
DE 35-12-179 and DE 35-34 645 dascribe the conversion of phenyl(~-hydroxy-2-propyl)ketone ~DAROCUR 1173), and similar acyloin compounds into ,:, 0~)152 21~ ~ ~? ~ PCr/US92/o(~
J t'~ r, i~ 1.
1 copolymerizable acrylated or methacrylated deriva-tives. The use of these copolymerizable photoinitiators in coatings and ink compositions give products, upon W curing, which are free of odors and other low m~lecular weight photoinitiation material.
Baeumer et al. from E. Merck, in a marketing publication, described the usefulness of the above functionalized photoinitiators in W -cured hard coating compositions which do not give off sol~ent extractables or low-molecular-weight photochemical products, which ooze to the ~urface of the cured coatings. No application of these photoinitiators is claimed in the W cure of pressure-sensitive adhe-sives.
J. P. Guarino and J. P. Ravijst, Journal of Radiation Curin~, July 1988, disclose the use of copolymerizable photoinitiators in coating composi-tions which emit very low levels of odor upon W
curing. No application is mentioned for W -cura~le pressure-sensitive adhesives.
Therefore, there exists a need for a PSA which is W -curable and which has a long shelf-life and a long hot melt pot life, e~en in the presence of multifunctional monomers, but which retains c~hesive strength, high-temperature shear strength, and tack and peel adhesion performance~ ~t is also desirable that the W curing be performed using conventional l~mps and in an atmosphere of air.
''~'~''''''''''' ".~`'.' 3~
~ '''`.`'.
W~ 'C7/US~2/09493
2122g2~ ' ,'~'' W -CURED HOT MELT PRESSURE-SENSITIVE ADHESIVES
Field of_the Invention This invention is related to photo-curable, pressure~~ensitive adhesives.
Backqround of the Invention High-performance pressure~-sensitive adhesives (PSAs) are normally characterized by the ability of the adhesive to withstand creep or shear deformation ~0 at high loadings and/or high temperatures while exhibiting adequate tac;~ and peel adheslon proper~
ties.
This balance of prope~ties is derived from the polymer structure of the PSA~ ~Such p~olymers are c~aracterized by a high~-molecular weight to provide the necess~ry resi~t~nce to she r deformatlon a~d by~
a low modulus of elasticity of the polymer ba~kbone t~ allow th~ polymer to conf~orm to a ~ubstrate surf~ce upon contact.~ ~:Certain~ surfa~e~energy and 3Q pularity requirements must::~also~ be satisfied for a ! go~d bond to form between: the~adhesive~: andl the substr~te.
The desired high molecu~lar~ weights~can::: be obtained either by primary~polymeri~zatlon of monomers t~ ~orm long-chain-length:backbon~s, or by crosslink~
ing of pre-existing~primary~polym~r:chains.
WV~ X2 2 1 2 ~ ~ 7 ~ PC~/USg~0~4s3 1 The PSA polymer backbone should consist of material of low enough modulus or high enough compli-ance to make a good contact with the adherent at the application temperature. This condition is normally satisfied by the use of material of low glass-transi-tion temperatures (Tg's), such as polymers or c~poly-mers of 2-ethyl-hexylacrylate, iso-octylacrylate, butylacrylate, ethylacrylate, methylacrylate, or the like.
Frequently, small amounts of other types of monomers are incorporated to modify the polarity, the rheological and surface properties of the polymer, such as acrylic aci~, maleic acid, ~-carboxyethylacr-ylate, esters of methacrylic acid, laurylacrylate, stearylacrylate, styrene, dibutylfumarate, dioctylma~eate, dioctylfumarate, vinylacetate, or the like.
Resistance to creep or shlear deformation in a high-performance PSA is normally the result of a hig~
internal cohesive strsngth. This condition can usually be obtained from a high primary polymer molecular weight. However, if the internal cohesive strength imparted by the polymer is insu~ficient, high in~ernal cohesive strength can also be obtained by incor~orating, into the polymer body, a high degree of interchain hydrogen bonding, ionic associa~
tion, or covalent crasslinking.
With hot melt PSAs, crossli~king the adhesive ~y radiation after~ coating is~ one of the~preferred 3Q methods of incorporating~high Gohesive streng~ih. The ! conv~rsivn of a f~uid whIch flows and ~oats~out ~ell,~
into a non-flowing ~is:coelastic material can be done with better con~rol by radiati~n crosslinking than by thermochemical mean:s.
In order for:a:polymer ~o be~crosslinkable:by W
radiation, the polymer~ ne~s to carry ~in~
unsaturation which,:in~the pre~eoce of~small amounts .. .. .. .
. . ;. - , WU~ 2 212~21 PCT/US~2/~9493 1 of added multi-vinyl-functional monomers and a photoinitiat~r, would resp~nd to vinyl addition polymerization upon W radiation. The combination of vinyl unsaturation on the polymer and multi-vinyl-functional monomers leads to very poor melt potliYes; polymer gelation in only an hour at the melt temperature is not uncommon with hot melt PSA formu-la~ions.
Crosslinking by W radiation of a polymer without vinyl unsaturation is also possible when a peroxy compound is present in addition to the multi~
vinyl~functional mo~omer and photoinitiator. Peroxy compounds which have been used are benzoylperoxide and t-butylperbenzoate. However, once again, the pot lives of the unfunctionali~ed hot melt polymer in the presence of the peroxy compound and multi-vinyl-functional monomers are very short, i.e., of the order of an hour at the melt te!mperature.
U.S. Patent No. 4,~181,752 cliscloses the manufac-~0 ture of P~As in web polymeriæativn of a polymer-monomer syrup by W irradiation. To form polymer molecules of sufficiently ~igh molecular weights, the UV energy o~ 300 and 400 nm wavelength is supplied at low intensities, 0.~01 to 0.07~ kWatts/m2 while maintaining the web temperature below 35C. In an on-web-syrup polymerization, the low W :.intensity r~quirement necessitates that cure takes place at relatively low web speeds of about 2 inches per minute to 2 feet per minute. Howev r, this irradia~
tion is preferably carried out under anaerobic conditions thus requiring ~n a~mosphere co~trol sy~tem.
U.S. Patent No. 4,052,527, discloses a method of production of UV crosslinkable ho~ melt pressure~
sen itive adhesives which cont~in~photoi:nitiators of the 3-(chlorinated aryloxy~2-hydroxypropyl acrylates or methacryl~tesO The photoinitiators were copoly-. ~ ~
wn ~ 91S~ ~ 12 ~ .~) 2 1. P~r/US~2/l~4~?~
1 merized into acrylic polymers and which containedother modifying monomers su~h as vinylics, and were made in solution, emulsion, or in bulk~ When not made in bulk, the solvent medium is vacuum-stripped so that the polymer can be coated as a melt between 120C and 180C. W cure is obtained from commercial medium-pressure lamps of 200 Wa~ts per inch intensi-ty. However, multiple passes under the W lamp are required to obtain moderate increases in shear strengths, 2.g., improvement of room-temperature shears from 4 minutes before W cure to only 0.5 hour shear after. passing 15 times under the W lamp, 1.5 hour shear after 2S passes, and 3.5 hours shear after 35 passes under the W lamp.
U.S. Patent No. 4,144,157 and DE 27-43-979 dis~loses the W crvsslinkability of acrylic pres-sure-sensitive adhesives which were exemplified by polymers which are made in and coated out of solu-tion, or when made in bulk are to be coated out of solution. The pressure-sensitive-adhesi~e materials are W -cross linkable to high shear strengths, because of copolymerizable photoinitiators in the pressure-sensitive adhesive polymer which belong to a class of (2-alkoxy,2-phenyl-2-benzoyl)ethyl 2 acrylates or methacrylates and the acrylate or methacrylate of benzoin or its derivati~e. The W
cure is obtained by radiation from high-p~essure mercury lamps or burners, with very-high-intensity ~utputs of from one lamp af ~00 Watts to four lamps of 2000 Watts each. ~espite the use of high-intensi-ty, high-pressure mercury lamps, the pressure-sensi~
~ive-adhesive material needs relatlvely high W
dosages of at least about 10 kJ/m2 before hig~ shear strengths can be obtained in the adhesive. The 3~ ad~ixkure of reactive cr~sslinking agents such as multiIunc~ion~l acrylic monomers to the pres~ure sensiti~e-adhesive material prio~ to coating and W
,, ~
" ' `' '.
. '.,~:~,'', . ;....
:, :` ;' W~ tl)~l~' 212 ~ 9 2 1 PCr/US~2/~4~3 1 cure is explicitly discouraged to prevent poor shelf stability of the coater-ready material.
U.S. Patent No. 4,~81,152 describes the synthe-sis of benzophenone derivatives which are copolymeri-za~le into a polymer backbone by way of acrylicfunctiona~ groups. The benzophenone derivatives are useful as a component in W -curable resin composi-tions and in anaerobic thermosetting adhesive compo-sitions.
U.S. Patent NQ~ 4, 672, 079 describes a method of manufao~uring polystyrene derivatives with W -activatable ~unctional groups, and the use of these compounds in the photopolymerization of monomer or oligomer mixture~ with ethylenic unsaturation for use in wood paints, paper lacquers, printing inks, engraving printed and integrated circuits, fabric printing, and the like, but not for pressure-sensi-tive adhesives.
European Patent Application ND. 87-30439~.2 and U.S. Patent No. 4,737,559 describe the synthesis and the use of benzophenone and acetophenone photo~
initiator derivatives, which are coplymerizable into a copolymer backbone by acrylic or acrylamide func-tional groups for use in adhesive compositions for human skin contact application. A pressure-sensitive adhesive is described which is a copolyme~ of acrylic monomers and the ketone deriv~tive, by means of which the copolymer can be UV~crosslinked. The amount of crosslinking ketone ~omonomer and the degree of polymerization of the copolymer are controlled, to obtain the right creep compliance ~alue for an~
enhanced leveil of initihl adhesion when applied to the skin, but r 5iSt objec~ionable adhesion build-up ovèr time.
DE 35-12-179 and DE 35-34 645 dascribe the conversion of phenyl(~-hydroxy-2-propyl)ketone ~DAROCUR 1173), and similar acyloin compounds into ,:, 0~)152 21~ ~ ~? ~ PCr/US92/o(~
J t'~ r, i~ 1.
1 copolymerizable acrylated or methacrylated deriva-tives. The use of these copolymerizable photoinitiators in coatings and ink compositions give products, upon W curing, which are free of odors and other low m~lecular weight photoinitiation material.
Baeumer et al. from E. Merck, in a marketing publication, described the usefulness of the above functionalized photoinitiators in W -cured hard coating compositions which do not give off sol~ent extractables or low-molecular-weight photochemical products, which ooze to the ~urface of the cured coatings. No application of these photoinitiators is claimed in the W cure of pressure-sensitive adhe-sives.
J. P. Guarino and J. P. Ravijst, Journal of Radiation Curin~, July 1988, disclose the use of copolymerizable photoinitiators in coating composi-tions which emit very low levels of odor upon W
curing. No application is mentioned for W -cura~le pressure-sensitive adhesives.
Therefore, there exists a need for a PSA which is W -curable and which has a long shelf-life and a long hot melt pot life, e~en in the presence of multifunctional monomers, but which retains c~hesive strength, high-temperature shear strength, and tack and peel adhesion performance~ ~t is also desirable that the W curing be performed using conventional l~mps and in an atmosphere of air.
''~'~''''''''''' ".~`'.' 3~
~ '''`.`'.
W~ 'C7/US~2/09493
2 ~2 2 ~ . !
1 Summary~of the Invention The present inYention relates to a pressure-sensi tive-adhesive copolymer comprising at least one copolymerizable photoinitiator monomer, at least one low-glass-transition-temperature monomer, and at least one multifunctional monomer and to a process for preparing such polymers.
The actinic radiation cure of the polymer is performed with light at about 240 to about 410 nm wavelength, light intensity of about 6 to about 10 kWatts/m~, and t~mperature of about 45OC to about 125C, under aerobic conditions. The resultant pressur~-sensitive adhesives exhibit cohesive ,strength and high-temperature shear strength which, when put to a static shear test, do not fail after several thousand minutes; tack performance of about 300 to about 500 N/m; peel adhesion perfo~mance of about 550 to about 650 N/m; a shelf-life at room t~mperature of more than about: 10 months, with no increase in the ~iscosity of the polymer; and a hot-melt pot-life at 100C of at least 10 d~ys, with little or substantially no increase in the viscosity of the polymer~
The coplymerizable photoinitiator monomers ~or use in the present invention are selected from the group consisting of benzoin compounds r acyloin compounds, and mixtures thereof, and, in a preferred embodiment of the invention, are sele ted from the - g~oup consisting of DAROCUR ZLI 3331 and DAROCUR
The multifunctional monomers for use in I the present invention are selected from the ~roup con~
sisting of diethyleneglycol~diacrylate "
tri~thyleneglycoldia~rylate, tripropyleneglycol~
35 diacrylate, 1,5-hexanedioldiacrylate, trimethylolpropanetriacrylate, trimethylc)lpropan~tr~
~ .....
W~ IS~ 2:1%2r) ~;J ~C~/USg2/Og4~3 --8~
1 methacryla~e, pentaerythritoltriacrylate, and mix-tures thereof.
The low-glass-transition-temperature monomers for use in the present invention are selected from the group consisting of 2-ethylhexylacrylate, iso~
octylacrylate, butylacrylatP, and mixtures thereof.
Other compounds such as acrylic acid, maleic acid, ~-carboxyethylacrylate, esters of methacrylic .
acid, laurylacrylate, st~arylacrylate, styrene, dibutyl- fumarate, dioc~ylmaleate, dioctylfumarate, and vinylacetate are added to the polymer to modi~y the properties of the polymer.
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~ /Q~ 2 1 2 2 9 2 1 PCr/lJS92/0~93 g l ~rie Description of the Drawinqs These and other features and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, wherein:
FIG. 1 is a graph of looptrack vs W dosage for -polym~r-2.
FIG. 2 is a graph o~ peel adhesion vs. W dosage for polymer-2.
FIG. 3 is a graph of melt viscosity at 100C vs heating period at 100C for polymer-4.
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2122!321 W~ IS~ PCT/U~92/~9493 1 Detailed Descri~tion The present invention relates to high-perfor-mance, W -cur~d, essentially acrylic-b~sed, pressure-sensitive adhesives which can be in the form of hot melts, solution adhesive compositions, or emulsion adhesi~es, and to methods for their manufacture.
The adhesive polymer compositions comprise low Tg monomers, such as 2-ethylhexylacrylate, iso-octyl-acrylate, butylacrylate, or the like. Preferably, the low Tg monomer is present in an amount of from a~out 40% to about ~0% by weight.
Other ~ypes of monomers are incorporated to modify the polarity and the rheological and surface properties of the polymer, such as acrylic acid, methacrylic acid, maleic acid, ~-carboxyethyl-acrylate, ~sters of methacrylic acid, laurylacrylate, stearylacrylate, styrene, vinyltoluene, dibutylfumarate, dioctylmaleate, dioctylfumarate, vinylacetate, or the like. These monomers are pre~ent in an amount of from about 10% to about 40 by weight.
The adhesive polymer contains a copolymerizable photoinitiator sold under the trade name "DAROCUR ZLI
3331" by E. Merck of ~armstadt, ~ermany, and which is 2S 4 ( 2-ac:ryloyloxyethoxy) phenyl- (2-hydroxy-2 propyl)ketone. The aoryloyl yroup makes the molecule copolymeri~able with other acrylic and vinylic monomers which make up the body of the adhesive polymer. The phot~initiator activity of DAROCUR ZLI
3331 r2sides in the phenyI(2-hydroxy-2-propyl~ketone moiety of the molecule. A compound with this latter structure is sold under the trade name "DAROCUR 1173"
by Merck . An add:itional j rel ated photoinitiator sold under thP trade name "DAROCUR 2959" is also sold 35 by Eo Merck. This compound is 4(2 hydroxyethoxy)phenyl-(2-hydroxy-2-propyljketone.
"~ 2 1 2 f~J !3 2 1 ~r/usg2/~ 49~
1 DAROCUR 2959 can also be made copolymerizable through the use of methacrylate ester and maleate halfester compounds. The maleate halfester can be formed in situ during the copolymerization of the acrylic and vinylic monomers and maleic anhydride in the presence of DAROCUR 2~59. The halfester forma-tion can be "pushed" to completion by the addition of a tertiary amine such as N,N,-dimethylbenzylamine at the termination of the polymerization reaction.
The copolymerizable photoinitiator monomer is presen~ in the range of from 0.1% to 10% by weight, and preferahly ~rom 0.5% to 5% by weight, in the adhesive c~polymer composition.
Another monomeric component which may be added to the polymer composition is, one or more vinyl esters present in a total amount of O up to about 20%
by weight based on the total we.ight of the monomers.
Vinyl esters contain from 2 to about 16 carbon atoms in the alkyl group of the acid. Representativ2 of the ~inyl esters are vinyl acetate, vinyl butyrate, vinyl propionate, vinyl isobutyrate, vinyl valerate, vinyl versi~ate, and the like. Vinyl ace~ate is preferred.
The monomer proportions are adjusted in such a way that the adhesive has a glass-transition tempera-ture of about -30C or le55 and at least about 50C
below the use temperature, giving a good bal~nce of adhesion and tack at room temperature and low temper~
atures The present inYention is, especially suitable for making hot melt PSAs, which have low melt viscosi~
ties, allowing them to~be easily coated out on a we~
as a thin film, even by a ~rinting proc~ss" Usually, low melt ~iscosities are o~tained by dilution of the P5A polymer with: relatîv~ly larg:e ~uantities of reactive diluent~. However, in ~he present inven-~, . . ...
.
W~ 0gl5~ 2122~ ~ PCr/US92/094~
1 tion, low melt viscosities are achieved by relatively low initial polymer molecular weight.
The PSA polymers of the present invention are compounded with small amounts of multifunctional acrylates or methacrylates, such as diethyleneglycol-diacrylate (DEGDA), triethyleneglycoldiacrylate (TEGDA), tripropyleneglycoldiacrylate ~TPGDA), 1,6-hexanedioldiacrylate~HDODA),trimethylolpropanetri-acrylate (TMPTA), trimethylolpropanetrimethacrylate (TMPTMA), pentaerythritoltriacrylate (PETA), or ~he like. The m~ltifunctional acrylates or methacrylates are presenk in the range of from 0.1% to 10% by weight, preferably from 1% to 5% by weight.
After coating the compounded polymer as a thin film, it can be W -cured very rapidly with small W
dosages of as low as 3 kJ/m2, to produce a PSA of very high cohesive strength and hi.gh-temperature shear strength, which retains a good balance of tack and peel perormance.
The UV radiation in thi~ invention is preferably by conventional, medium-pressure mercury lamps, with emission bands ranging from 240 nm to 410 nm, light intensities from 6 to 10 kWatts/m2, and temperatures from 45C to 125C at the web surface. Unli~e other ~5 W cures, the W cures of the present invention are performed in an aerobic atmosphere.
Also unlike other PSAS, which contain multifunctional acrylic monom~rs, the PSAs of the present invention respond readily to W crosslinking, and the coater-ready hot melt PSA composition has an excellent shelf-life a~ well as an excellent melt pot-life. Storage of the polymer at room temperature of more than about 10 months results in no increase in the viscosity of the polymer. Similarly, exposing the pol~mer to 100C for 10 day~ results in only a slight increase in the viscosity of the polymer, from . ~;''' `;
',' :.
~ }'~ 2122~2 I P~l/lJS92/()~
1 its initial viscosity of 16 Pascal seconds to only 28 Pascal seconds after 10 ~ays at 100C.
The tack and peel adhesion performance of the PSAs of the present invention are relatively insensitive to wide variations in the W irradiation dosag~ needed for cure, to variations in the polymers' initial viscosity, and to levels of added multifunctional acrylic monomers. The decrease in tack ~nd peel adhesion upon accelerated aging is also0 smaller than in conventional W -cured PSAs.
Polymer Synthesis In a 1000-5000 ml jacketed resin kettle, which is equipped with a strong mechanical stirrer, thermocouple, water-cooled co~denser, and nitrogen blanke'ing, is polymerized a mixture of acrylic and other vinylic monomers; copolymerizable photoinitia~or; polymerization initiator, which can be a peroxide or other polymeri.zation initiator such as those sold under the trade name "VAZO" by DuPont of Wilmington, Delaware; iand chain transfer modulators.
About 10% of the mixturP is placed in the reactor, and the polymerization is allowed to initiate. Heating of the reactin~ mix is provided throuyh the jacket from a circulating oil bath.
After the reaction of the initial mixture has subsided, the remainder ~f the mix is added to the reactor, via a metering pump~ over a: period of 1 to
1 Summary~of the Invention The present inYention relates to a pressure-sensi tive-adhesive copolymer comprising at least one copolymerizable photoinitiator monomer, at least one low-glass-transition-temperature monomer, and at least one multifunctional monomer and to a process for preparing such polymers.
The actinic radiation cure of the polymer is performed with light at about 240 to about 410 nm wavelength, light intensity of about 6 to about 10 kWatts/m~, and t~mperature of about 45OC to about 125C, under aerobic conditions. The resultant pressur~-sensitive adhesives exhibit cohesive ,strength and high-temperature shear strength which, when put to a static shear test, do not fail after several thousand minutes; tack performance of about 300 to about 500 N/m; peel adhesion perfo~mance of about 550 to about 650 N/m; a shelf-life at room t~mperature of more than about: 10 months, with no increase in the ~iscosity of the polymer; and a hot-melt pot-life at 100C of at least 10 d~ys, with little or substantially no increase in the viscosity of the polymer~
The coplymerizable photoinitiator monomers ~or use in the present invention are selected from the group consisting of benzoin compounds r acyloin compounds, and mixtures thereof, and, in a preferred embodiment of the invention, are sele ted from the - g~oup consisting of DAROCUR ZLI 3331 and DAROCUR
The multifunctional monomers for use in I the present invention are selected from the ~roup con~
sisting of diethyleneglycol~diacrylate "
tri~thyleneglycoldia~rylate, tripropyleneglycol~
35 diacrylate, 1,5-hexanedioldiacrylate, trimethylolpropanetriacrylate, trimethylc)lpropan~tr~
~ .....
W~ IS~ 2:1%2r) ~;J ~C~/USg2/Og4~3 --8~
1 methacryla~e, pentaerythritoltriacrylate, and mix-tures thereof.
The low-glass-transition-temperature monomers for use in the present invention are selected from the group consisting of 2-ethylhexylacrylate, iso~
octylacrylate, butylacrylatP, and mixtures thereof.
Other compounds such as acrylic acid, maleic acid, ~-carboxyethylacrylate, esters of methacrylic .
acid, laurylacrylate, st~arylacrylate, styrene, dibutyl- fumarate, dioc~ylmaleate, dioctylfumarate, and vinylacetate are added to the polymer to modi~y the properties of the polymer.
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~ /Q~ 2 1 2 2 9 2 1 PCr/lJS92/0~93 g l ~rie Description of the Drawinqs These and other features and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, wherein:
FIG. 1 is a graph of looptrack vs W dosage for -polym~r-2.
FIG. 2 is a graph o~ peel adhesion vs. W dosage for polymer-2.
FIG. 3 is a graph of melt viscosity at 100C vs heating period at 100C for polymer-4.
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2122!321 W~ IS~ PCT/U~92/~9493 1 Detailed Descri~tion The present invention relates to high-perfor-mance, W -cur~d, essentially acrylic-b~sed, pressure-sensitive adhesives which can be in the form of hot melts, solution adhesive compositions, or emulsion adhesi~es, and to methods for their manufacture.
The adhesive polymer compositions comprise low Tg monomers, such as 2-ethylhexylacrylate, iso-octyl-acrylate, butylacrylate, or the like. Preferably, the low Tg monomer is present in an amount of from a~out 40% to about ~0% by weight.
Other ~ypes of monomers are incorporated to modify the polarity and the rheological and surface properties of the polymer, such as acrylic acid, methacrylic acid, maleic acid, ~-carboxyethyl-acrylate, ~sters of methacrylic acid, laurylacrylate, stearylacrylate, styrene, vinyltoluene, dibutylfumarate, dioctylmaleate, dioctylfumarate, vinylacetate, or the like. These monomers are pre~ent in an amount of from about 10% to about 40 by weight.
The adhesive polymer contains a copolymerizable photoinitiator sold under the trade name "DAROCUR ZLI
3331" by E. Merck of ~armstadt, ~ermany, and which is 2S 4 ( 2-ac:ryloyloxyethoxy) phenyl- (2-hydroxy-2 propyl)ketone. The aoryloyl yroup makes the molecule copolymeri~able with other acrylic and vinylic monomers which make up the body of the adhesive polymer. The phot~initiator activity of DAROCUR ZLI
3331 r2sides in the phenyI(2-hydroxy-2-propyl~ketone moiety of the molecule. A compound with this latter structure is sold under the trade name "DAROCUR 1173"
by Merck . An add:itional j rel ated photoinitiator sold under thP trade name "DAROCUR 2959" is also sold 35 by Eo Merck. This compound is 4(2 hydroxyethoxy)phenyl-(2-hydroxy-2-propyljketone.
"~ 2 1 2 f~J !3 2 1 ~r/usg2/~ 49~
1 DAROCUR 2959 can also be made copolymerizable through the use of methacrylate ester and maleate halfester compounds. The maleate halfester can be formed in situ during the copolymerization of the acrylic and vinylic monomers and maleic anhydride in the presence of DAROCUR 2~59. The halfester forma-tion can be "pushed" to completion by the addition of a tertiary amine such as N,N,-dimethylbenzylamine at the termination of the polymerization reaction.
The copolymerizable photoinitiator monomer is presen~ in the range of from 0.1% to 10% by weight, and preferahly ~rom 0.5% to 5% by weight, in the adhesive c~polymer composition.
Another monomeric component which may be added to the polymer composition is, one or more vinyl esters present in a total amount of O up to about 20%
by weight based on the total we.ight of the monomers.
Vinyl esters contain from 2 to about 16 carbon atoms in the alkyl group of the acid. Representativ2 of the ~inyl esters are vinyl acetate, vinyl butyrate, vinyl propionate, vinyl isobutyrate, vinyl valerate, vinyl versi~ate, and the like. Vinyl ace~ate is preferred.
The monomer proportions are adjusted in such a way that the adhesive has a glass-transition tempera-ture of about -30C or le55 and at least about 50C
below the use temperature, giving a good bal~nce of adhesion and tack at room temperature and low temper~
atures The present inYention is, especially suitable for making hot melt PSAs, which have low melt viscosi~
ties, allowing them to~be easily coated out on a we~
as a thin film, even by a ~rinting proc~ss" Usually, low melt ~iscosities are o~tained by dilution of the P5A polymer with: relatîv~ly larg:e ~uantities of reactive diluent~. However, in ~he present inven-~, . . ...
.
W~ 0gl5~ 2122~ ~ PCr/US92/094~
1 tion, low melt viscosities are achieved by relatively low initial polymer molecular weight.
The PSA polymers of the present invention are compounded with small amounts of multifunctional acrylates or methacrylates, such as diethyleneglycol-diacrylate (DEGDA), triethyleneglycoldiacrylate (TEGDA), tripropyleneglycoldiacrylate ~TPGDA), 1,6-hexanedioldiacrylate~HDODA),trimethylolpropanetri-acrylate (TMPTA), trimethylolpropanetrimethacrylate (TMPTMA), pentaerythritoltriacrylate (PETA), or ~he like. The m~ltifunctional acrylates or methacrylates are presenk in the range of from 0.1% to 10% by weight, preferably from 1% to 5% by weight.
After coating the compounded polymer as a thin film, it can be W -cured very rapidly with small W
dosages of as low as 3 kJ/m2, to produce a PSA of very high cohesive strength and hi.gh-temperature shear strength, which retains a good balance of tack and peel perormance.
The UV radiation in thi~ invention is preferably by conventional, medium-pressure mercury lamps, with emission bands ranging from 240 nm to 410 nm, light intensities from 6 to 10 kWatts/m2, and temperatures from 45C to 125C at the web surface. Unli~e other ~5 W cures, the W cures of the present invention are performed in an aerobic atmosphere.
Also unlike other PSAS, which contain multifunctional acrylic monom~rs, the PSAs of the present invention respond readily to W crosslinking, and the coater-ready hot melt PSA composition has an excellent shelf-life a~ well as an excellent melt pot-life. Storage of the polymer at room temperature of more than about 10 months results in no increase in the viscosity of the polymer. Similarly, exposing the pol~mer to 100C for 10 day~ results in only a slight increase in the viscosity of the polymer, from . ~;''' `;
',' :.
~ }'~ 2122~2 I P~l/lJS92/()~
1 its initial viscosity of 16 Pascal seconds to only 28 Pascal seconds after 10 ~ays at 100C.
The tack and peel adhesion performance of the PSAs of the present invention are relatively insensitive to wide variations in the W irradiation dosag~ needed for cure, to variations in the polymers' initial viscosity, and to levels of added multifunctional acrylic monomers. The decrease in tack ~nd peel adhesion upon accelerated aging is also0 smaller than in conventional W -cured PSAs.
Polymer Synthesis In a 1000-5000 ml jacketed resin kettle, which is equipped with a strong mechanical stirrer, thermocouple, water-cooled co~denser, and nitrogen blanke'ing, is polymerized a mixture of acrylic and other vinylic monomers; copolymerizable photoinitia~or; polymerization initiator, which can be a peroxide or other polymeri.zation initiator such as those sold under the trade name "VAZO" by DuPont of Wilmington, Delaware; iand chain transfer modulators.
About 10% of the mixturP is placed in the reactor, and the polymerization is allowed to initiate. Heating of the reactin~ mix is provided throuyh the jacket from a circulating oil bath.
After the reaction of the initial mixture has subsided, the remainder ~f the mix is added to the reactor, via a metering pump~ over a: period of 1 to
3 hours, while maintaining the reaction temperature in the range of 80~C ~o llO~C. The reaction temperature varies depending on the hal~life temperature of the ini~iators u~ed~
The polymerization prcduct is sampled ~or percent conversion and for melt viscosity measurements. The polymerization pr~duct is immediately compounde~ with the multifunctional `'~ ,',","' ~' W~ 5~ 2 l~2~ ~
1 acrylic monomer, inside the reactor, before the product is discharged as coater-ready material.
Adhesive Coatinq and W Cure The compounded polymer is direct-coated on about 50 ~m polyester film at a coatiny weight ranging from about 30 to about 40 g/m2, and is cured by W
radiation from two conventional medium-pressure mercury lamps which have spectral emissions from 240 nm to 410 nm, and light intensities from 6 to 10 kWatts/m2. The coated polyester film is carried on a moving web under the W radiation source, and the web temp~rature is from about 45C to about 125C. The W dosage which the coated adhe~ive film receives is controlled by the W lamp-intensity setting and web speed. All W cure is performed in an aerobic atmosphere, and no special precautions to exclude air are required.
After the adhesive film is cured, it is laminated with a sheet of release liner, for protection, until it is ready Eor application. When solution adhesives or emulsioll adhesives are to be coated and curedj the major portion of the low volatiles are removed ~rom the coated materîal, before W cure. The volatlles are removed by placing the ~oated material in a forced-air oven at about 70~ for about 5 minutes be~ore cure, and r to remove the last traces of low volatiles, for another 15 minutes after cure. -~ . .
Adhesive Performance Testina ~ ~-Loo~ack Samples of th~ coated adhesive construction are cut in 2054 cm x about 20~cm t~st~strips~. ~Th~ strips are formed into a Ioop, which~ is brought, in an Instron t~n~ile tester, into contact with a standard 35 st2inless steel test paneI ~ a rate of abo~t 30 ~ ~
cm~minu e, with no other ~orce than the weight of the ~;
strip itself. After a~rief contact period;,~the loop~
., ~-~ fl~ 212 2 9 2 ~ Pcr/us~2/os4s~
1 is peeled from the test panel at about 30 cm/minute.
The force to remove the adhesive loop is measured, in newtons ~N3/m. Tests are performed in triplicate.
The possible adhesion failure modes are: panel (p~
= no visible stain on panel; panel staining (ps) =
visible stain on panel, but no sticky residue;
cohesi~e (c) = adhesive film splits during the test, leaving residue films both on panel and on facestock;
facestock failure (f) = ad~esive delamina-tes completely from faces~ock; mixed (p/c or p/f) =
failure with mixed p/c or p/f~
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W~/0~ 2 l2~,'92 L P~l/US92/09~
1 180 Peel_Adhesion Samples were cut in 2.54 cm x about 20 cm test strips, which were rolled down on standard stainless ~teel test panels with about a 2 kg rubber-clad steel roller, back and forth once at a rate of about 30 cm/minute. After a dwell time of Z0 minutes at standard tes~ing laboratory conditions, the test s~rips were peeled away from the test panel in an Instron tensile tester at 180 to the test panel, i.e., folded back on itself and parallel to the surface of the panel, at a rate of about 30 cm/minu~e. The force to remove the adhesive test strip from the test panel was measured in N/m. Tests were performed in triplicate. Possible modes of5 adhesion failures are the same as above.
Static Shear Samples were cut in 1.27 cm x about ~ cm and 2.54 cm x about 6 cm test st;rips. When the shear test was per~ormed at room temperature (RTS), the 1.27 cm x 5 cm test strips were applied on a standard stainless steel test panel, making a sample-overlap of 1.27 cm x 1.27 cm with the test panel. The sample portion on the test panel was rolled down with about a 2 kg rubber-clad steel roller, back and forth once at a rate vf 30 cm/minute. The free end of the test strip was folded back on itself, and a small hole was made at the ~ree end, where:a load of 500 g could be attached during the test.~
Tha sample's free end can be reinforced with aluminum foil, cardboard, or the like, to prevent the sample from tearing when the load is applied~ `After~
a dwell time of at least 20: minutes at standard laboratory testing condition , the test panels, with the test strips on it, were placed on a rack in a vertical position, and a load of 500 g was ~ttached t~ the hole at ~he test strips' free end~ The time, in minu~es, for the sample to fail and fall~off the .
~ .
~ 21~ ,? 9 ~ C~ S~2/~94~
17- :
1 panel was measured by means of a timing device. The modes of adhesive failure are recorded as above. `
Tests were performed in triplicate.
When a sample does not fail after several thousand minutes, without any creeping of the test strip down the test panel surface, it is recorded either as "infinite, NC" or, e.g., 'i4000+, NC" (NC =
no creep).
When the shear test was perfo~med at an elevated temperature (ETS), either at 70C, 100C, or at any higher temperature, the 2.54 cm x 6 cm test strips were used, ~nd were applied on the test panels t~
make a sample-overlap of 2~54 cm x 2.54 cm with the test panel. The rack with panels, test strips, S~0 g load and timing device are placed in an oven, equipped with a constant-temperature-control mechanism.
Example 1 .
PolY~er 5ynthe~s's -:
PSA polymer-1 (P-l) was a control and comprised 58% by weight 2-ethylhexylacr-ylate, 24~ methyl~
acrylate, 10% ~-carboxyethylacrylate, and 8% dibutyl-fumarate. P-1 had a weight-averaged molecular weight :
(Mw) of 385,000 and a number-averaged molecular weight (~) of 66,000, as determined by size exclusion -chromatography (SEC). After compounding with 2% by -~
weight of HDODA, P-l had a 100C Brookfield melt ~ :~
viscosity of 46.5 pascal seconds (Pa.s. ), using the ~29 spindle at 10 rpm. It was aIso compounded with ~% by weight of pho~oinitiator DAROCU~ 1173.
PSA P-2 was the test~material, made according to the present invention, and~comprised 2% by weight of ~:~
the copolymerizable photoinitiato~ DARQCUR ZLI 3331, 56% ~-ethylhexylacrylate, 24% methy1acrylate, 10% ~
carboxyethylacrylate, and 8~ dibutylfumarate. P-2 had a M~ ss,noo, a ~ = 20,000 by SEC, and a 100C .
Brookfield melt viscosity of 10 Pa.s. after ' w~ s 2 I 7 ? 9 ? I pcr/us~/o94~
. r~l J r~ .
1 compounding with 2% by weight of HDODA. The compositions of the P-l and P-2 are summarized in Table I.
Table I
P-l P-2 2-ethylhPxylacrylate 58 56 methylacrylate 24 24 ~-carboxyethylacrylate 10 10 dibutyl~umara~e 8 8 HDODA, compounded after polymerization 2 2 P-2 developed infinite shear (4000+ minutes) after on~y 3 kJ/m2 of W exposure, whereas the control, P-:L, with the conventional photoinitiator, did not form cohesive strength, even with 9 kJ/m' of W . The results obtained wi.th P-1 and P;2 are ~ :.
~ummarized in Table II.
~ . ~,., 1~OO 70C
W LQOP- Pee!1 RTS ETS
~ taCk (N/m)(Min ) ~L
P--1 - .
Control 9 540 p/c 1000 c 7 c 0 c ` `~ :
P-2 0 4 c - ~...
P-2 3 500 p 560 p 4000+,NC :
4000~,NC
P-2 9 410 p 450 p :4000;+,NC
4000+,NC
c = cohesive, adhesive film splits during:the ~est, leaving residue :f:ilm~ both on pa~el and fa~estock p ~ no visible stain on panel NC = no creep P~2, which was UV crosslinkable by a mechanism using a copolymeri~able photoinitiator, was~not only unique in it~ rapi:d response to W cure in~dcveloping:
high cohesiv~ str~ngth,:but~the adhesive performance : ~ : .. .~
w~ 2 I 2 ~ 9 2 :~ f~r/US~2/~949~
-19~ :
1 in looptac:k and 180 pee:L adhesion remained essentially the same over a wide range of W
radiation dosage, from 3 to ~ kJtm2. This corresponds to a web speed variation of about 50 to about 15 m/minute on a conventional W printing press, and indira~es that W overcure is improbable under these conditions. FIGs. 1 and 2 illustrate a relatively fl~t response of looptack and ~80 peel adhesion of P-2 to W radiation dosage.
ExamPle 2 .:
Polymer synthesis -~
Adhasive performance ~f PSAs which are made according to the présent invention is characterized -; by a low sensitivity to variations in the 5tarting polymer viscosity, its formulation, and the UV
irradiation dosage.
Th~ synthesis of P-2 was repeated twice more (P~
2a and P-2b). Due to slightly different polymeriza tion conditions, the resultan1: products exhibited .:.~0 different 100C melt ~iscosities -- 35 Pa.s. for the first repe~t, and 65 Pa.s. for the second repeat ~
indicating different polymer molecular weiyhts in the prod~cts. The polymers were subse~uently compounded with 1.0% by weight, 1.5% by weight, 2.0% by weight, and 5.0~ by weight of HDQDA, coated and cured with 3 to 9 kJ/m2 of W ~ The compositions of the p~lymers are su~mari~ed in Table III.
- Table_IlI .. '.', 30 2-e~hylhexylacrylate 56 56 56 56 -~
methylacrylate : 24 2424 ' 24 ~
~-carboxyethylacrylate10 10 10 10 :~ ;
dibutylfumarate :8 ~ 8 8 HD~DA, compounded after poly~erization 1 1.5 2 5 All samples gave i~ini~e shears, and, despite the diffirences in ini~ial m~lt viscosities, ~`
. ~ r ~ ' '',~
W~J0~1~2 2 12 2 9 ~ :1 PCT/US92/0~4~3 --~ O ~
l different le~els of HDODA, and different W dosages, the looptack and peel adhesion performance were about the same over the range of these differences. The results are summarized in Table IV.
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21~
1 Table IV -;
Low Dependence of_Adhesive Performance on Startinq PolYmer Viscosity~ Formulation, an~ W Irradiation Dosaae (Adhesive coating weight 35-40 g/m2 on 2 mil PET film; tack, peel, and shear tests orl st~inless steel panels) Loop- 130 W tack Peel kJ/m2 ~NL~ (Nlm) Static Shear .
10 ~
10 Pa.s. at 100C, 2% ~DODA
3 501 p 561 p In~inite 7~C
ETS
The polymerization prcduct is sampled ~or percent conversion and for melt viscosity measurements. The polymerization pr~duct is immediately compounde~ with the multifunctional `'~ ,',","' ~' W~ 5~ 2 l~2~ ~
1 acrylic monomer, inside the reactor, before the product is discharged as coater-ready material.
Adhesive Coatinq and W Cure The compounded polymer is direct-coated on about 50 ~m polyester film at a coatiny weight ranging from about 30 to about 40 g/m2, and is cured by W
radiation from two conventional medium-pressure mercury lamps which have spectral emissions from 240 nm to 410 nm, and light intensities from 6 to 10 kWatts/m2. The coated polyester film is carried on a moving web under the W radiation source, and the web temp~rature is from about 45C to about 125C. The W dosage which the coated adhe~ive film receives is controlled by the W lamp-intensity setting and web speed. All W cure is performed in an aerobic atmosphere, and no special precautions to exclude air are required.
After the adhesive film is cured, it is laminated with a sheet of release liner, for protection, until it is ready Eor application. When solution adhesives or emulsioll adhesives are to be coated and curedj the major portion of the low volatiles are removed ~rom the coated materîal, before W cure. The volatlles are removed by placing the ~oated material in a forced-air oven at about 70~ for about 5 minutes be~ore cure, and r to remove the last traces of low volatiles, for another 15 minutes after cure. -~ . .
Adhesive Performance Testina ~ ~-Loo~ack Samples of th~ coated adhesive construction are cut in 2054 cm x about 20~cm t~st~strips~. ~Th~ strips are formed into a Ioop, which~ is brought, in an Instron t~n~ile tester, into contact with a standard 35 st2inless steel test paneI ~ a rate of abo~t 30 ~ ~
cm~minu e, with no other ~orce than the weight of the ~;
strip itself. After a~rief contact period;,~the loop~
., ~-~ fl~ 212 2 9 2 ~ Pcr/us~2/os4s~
1 is peeled from the test panel at about 30 cm/minute.
The force to remove the adhesive loop is measured, in newtons ~N3/m. Tests are performed in triplicate.
The possible adhesion failure modes are: panel (p~
= no visible stain on panel; panel staining (ps) =
visible stain on panel, but no sticky residue;
cohesi~e (c) = adhesive film splits during the test, leaving residue films both on panel and on facestock;
facestock failure (f) = ad~esive delamina-tes completely from faces~ock; mixed (p/c or p/f) =
failure with mixed p/c or p/f~
. -- . .
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~, ~ ;,.
, . ~.~ . ...
. , . , "
-- . .
W~/0~ 2 l2~,'92 L P~l/US92/09~
1 180 Peel_Adhesion Samples were cut in 2.54 cm x about 20 cm test strips, which were rolled down on standard stainless ~teel test panels with about a 2 kg rubber-clad steel roller, back and forth once at a rate of about 30 cm/minute. After a dwell time of Z0 minutes at standard tes~ing laboratory conditions, the test s~rips were peeled away from the test panel in an Instron tensile tester at 180 to the test panel, i.e., folded back on itself and parallel to the surface of the panel, at a rate of about 30 cm/minu~e. The force to remove the adhesive test strip from the test panel was measured in N/m. Tests were performed in triplicate. Possible modes of5 adhesion failures are the same as above.
Static Shear Samples were cut in 1.27 cm x about ~ cm and 2.54 cm x about 6 cm test st;rips. When the shear test was per~ormed at room temperature (RTS), the 1.27 cm x 5 cm test strips were applied on a standard stainless steel test panel, making a sample-overlap of 1.27 cm x 1.27 cm with the test panel. The sample portion on the test panel was rolled down with about a 2 kg rubber-clad steel roller, back and forth once at a rate vf 30 cm/minute. The free end of the test strip was folded back on itself, and a small hole was made at the ~ree end, where:a load of 500 g could be attached during the test.~
Tha sample's free end can be reinforced with aluminum foil, cardboard, or the like, to prevent the sample from tearing when the load is applied~ `After~
a dwell time of at least 20: minutes at standard laboratory testing condition , the test panels, with the test strips on it, were placed on a rack in a vertical position, and a load of 500 g was ~ttached t~ the hole at ~he test strips' free end~ The time, in minu~es, for the sample to fail and fall~off the .
~ .
~ 21~ ,? 9 ~ C~ S~2/~94~
17- :
1 panel was measured by means of a timing device. The modes of adhesive failure are recorded as above. `
Tests were performed in triplicate.
When a sample does not fail after several thousand minutes, without any creeping of the test strip down the test panel surface, it is recorded either as "infinite, NC" or, e.g., 'i4000+, NC" (NC =
no creep).
When the shear test was perfo~med at an elevated temperature (ETS), either at 70C, 100C, or at any higher temperature, the 2.54 cm x 6 cm test strips were used, ~nd were applied on the test panels t~
make a sample-overlap of 2~54 cm x 2.54 cm with the test panel. The rack with panels, test strips, S~0 g load and timing device are placed in an oven, equipped with a constant-temperature-control mechanism.
Example 1 .
PolY~er 5ynthe~s's -:
PSA polymer-1 (P-l) was a control and comprised 58% by weight 2-ethylhexylacr-ylate, 24~ methyl~
acrylate, 10% ~-carboxyethylacrylate, and 8% dibutyl-fumarate. P-1 had a weight-averaged molecular weight :
(Mw) of 385,000 and a number-averaged molecular weight (~) of 66,000, as determined by size exclusion -chromatography (SEC). After compounding with 2% by -~
weight of HDODA, P-l had a 100C Brookfield melt ~ :~
viscosity of 46.5 pascal seconds (Pa.s. ), using the ~29 spindle at 10 rpm. It was aIso compounded with ~% by weight of pho~oinitiator DAROCU~ 1173.
PSA P-2 was the test~material, made according to the present invention, and~comprised 2% by weight of ~:~
the copolymerizable photoinitiato~ DARQCUR ZLI 3331, 56% ~-ethylhexylacrylate, 24% methy1acrylate, 10% ~
carboxyethylacrylate, and 8~ dibutylfumarate. P-2 had a M~ ss,noo, a ~ = 20,000 by SEC, and a 100C .
Brookfield melt viscosity of 10 Pa.s. after ' w~ s 2 I 7 ? 9 ? I pcr/us~/o94~
. r~l J r~ .
1 compounding with 2% by weight of HDODA. The compositions of the P-l and P-2 are summarized in Table I.
Table I
P-l P-2 2-ethylhPxylacrylate 58 56 methylacrylate 24 24 ~-carboxyethylacrylate 10 10 dibutyl~umara~e 8 8 HDODA, compounded after polymerization 2 2 P-2 developed infinite shear (4000+ minutes) after on~y 3 kJ/m2 of W exposure, whereas the control, P-:L, with the conventional photoinitiator, did not form cohesive strength, even with 9 kJ/m' of W . The results obtained wi.th P-1 and P;2 are ~ :.
~ummarized in Table II.
~ . ~,., 1~OO 70C
W LQOP- Pee!1 RTS ETS
~ taCk (N/m)(Min ) ~L
P--1 - .
Control 9 540 p/c 1000 c 7 c 0 c ` `~ :
P-2 0 4 c - ~...
P-2 3 500 p 560 p 4000+,NC :
4000~,NC
P-2 9 410 p 450 p :4000;+,NC
4000+,NC
c = cohesive, adhesive film splits during:the ~est, leaving residue :f:ilm~ both on pa~el and fa~estock p ~ no visible stain on panel NC = no creep P~2, which was UV crosslinkable by a mechanism using a copolymeri~able photoinitiator, was~not only unique in it~ rapi:d response to W cure in~dcveloping:
high cohesiv~ str~ngth,:but~the adhesive performance : ~ : .. .~
w~ 2 I 2 ~ 9 2 :~ f~r/US~2/~949~
-19~ :
1 in looptac:k and 180 pee:L adhesion remained essentially the same over a wide range of W
radiation dosage, from 3 to ~ kJtm2. This corresponds to a web speed variation of about 50 to about 15 m/minute on a conventional W printing press, and indira~es that W overcure is improbable under these conditions. FIGs. 1 and 2 illustrate a relatively fl~t response of looptack and ~80 peel adhesion of P-2 to W radiation dosage.
ExamPle 2 .:
Polymer synthesis -~
Adhasive performance ~f PSAs which are made according to the présent invention is characterized -; by a low sensitivity to variations in the 5tarting polymer viscosity, its formulation, and the UV
irradiation dosage.
Th~ synthesis of P-2 was repeated twice more (P~
2a and P-2b). Due to slightly different polymeriza tion conditions, the resultan1: products exhibited .:.~0 different 100C melt ~iscosities -- 35 Pa.s. for the first repe~t, and 65 Pa.s. for the second repeat ~
indicating different polymer molecular weiyhts in the prod~cts. The polymers were subse~uently compounded with 1.0% by weight, 1.5% by weight, 2.0% by weight, and 5.0~ by weight of HDQDA, coated and cured with 3 to 9 kJ/m2 of W ~ The compositions of the p~lymers are su~mari~ed in Table III.
- Table_IlI .. '.', 30 2-e~hylhexylacrylate 56 56 56 56 -~
methylacrylate : 24 2424 ' 24 ~
~-carboxyethylacrylate10 10 10 10 :~ ;
dibutylfumarate :8 ~ 8 8 HD~DA, compounded after poly~erization 1 1.5 2 5 All samples gave i~ini~e shears, and, despite the diffirences in ini~ial m~lt viscosities, ~`
. ~ r ~ ' '',~
W~J0~1~2 2 12 2 9 ~ :1 PCT/US92/0~4~3 --~ O ~
l different le~els of HDODA, and different W dosages, the looptack and peel adhesion performance were about the same over the range of these differences. The results are summarized in Table IV.
,~-~ - .. ,;
~ ~ .
~:
;
~; ~"
:;
W~ 2 1 2 2 ~ 2 1 Pcrfu~ g~
21~
1 Table IV -;
Low Dependence of_Adhesive Performance on Startinq PolYmer Viscosity~ Formulation, an~ W Irradiation Dosaae (Adhesive coating weight 35-40 g/m2 on 2 mil PET film; tack, peel, and shear tests orl st~inless steel panels) Loop- 130 W tack Peel kJ/m2 ~NL~ (Nlm) Static Shear .
10 ~
10 Pa.s. at 100C, 2% ~DODA
3 501 p 561 p In~inite 7~C
ETS
4.5 453 p 467 p Infinite 70C
ETS
6 429 p 456 p Infinite 700C
ETS
9 414 p 452 p Infinite 70C
ETS
1.5% HDO~A
4.5 470 p 514 p Infinite RTS :~
6 445 p 467 p Infinite RTS ~: .-9 396 p 436 p Infinite RTS
~; . .
1.0% H~ODA .
4.5 486 p 469 p Infinite RTS
6 463 p 434 p Infinite RTS ~ ~:
9 443 p 415 p Infinite RTS
25 5.0% HDODA
3 545 p 650 p Infinite RTS
6 4:59 p 475 p Infinite ~TS ~:~
P-2a 35 Pa.s. at 100C, 2.0~ HDQDA
. .
3 51~ p :566 p Infinite 70~C
ETS
6 453 p 455 p In~inite i7Q~C
ETS
P-2b . ~ ~-.
65 Pa.s. a~ 100C, 2~0% HDODA
3 : 568 p 628:~p In~ini~e ~:0C :
ETS
~ ~84 p 458 p Infinite 70C
ETS
W~ 2 2 ~ 2 2 ~ ~ 1 pcr/vs9~/o(~49~
-22- ~
1 ETS = Elevated Temperature Shear; RTS = Room Temperature Shear; p = All sample failures were .
panel failure , ~"-.
, " .
"~
. .:, -W~)~3~ 2 :1 ~ 2 9 2 1 PCT/US~2/094~
1 Exa~ple 3 Post Cure Coated and W -cure~ adhPsives of the present invention have better aging stability than adhesives which are made by conventional UV curing methods.
~ rawdowns of the PSAs of the present in~ention w2re subjected to an accelerated aging at 60C over a period of one week. Table v shows that the drop in the adhesive's looptack and 180 peel is only about 10~-20% from the original values. In conveQtional W -cured PSAs, losses in excess of 50% in these adhesion properties are Yery common.
~0 ", " ''~
.~.~
~,........
, ~ ~
"",''' ~'~ '', ql~2 1 ~?J 2 ~.3 21. Pcr/uss2/o949~
1 Table V
optack_and Peel Performance after One Week's Aqinq at 60C
(Adhesi~e coating weight 35 40 g/m2 on 2 mil PET film; tack, peel, and shear tests on stainless steel panels) W, kJ/m2 Looptack, N/m 180 Peel, Nlm Ini- After Ini- After 1~ tial ~g~ %~ tial Aqinq %_ 10 Pa~s. at 100C ~ -2.0% HDODA
4,5 453 403 11 467 426 ..
9 ......
ETS
6 429 p 456 p Infinite 700C
ETS
9 414 p 452 p Infinite 70C
ETS
1.5% HDO~A
4.5 470 p 514 p Infinite RTS :~
6 445 p 467 p Infinite RTS ~: .-9 396 p 436 p Infinite RTS
~; . .
1.0% H~ODA .
4.5 486 p 469 p Infinite RTS
6 463 p 434 p Infinite RTS ~ ~:
9 443 p 415 p Infinite RTS
25 5.0% HDODA
3 545 p 650 p Infinite RTS
6 4:59 p 475 p Infinite ~TS ~:~
P-2a 35 Pa.s. at 100C, 2.0~ HDQDA
. .
3 51~ p :566 p Infinite 70~C
ETS
6 453 p 455 p In~inite i7Q~C
ETS
P-2b . ~ ~-.
65 Pa.s. a~ 100C, 2~0% HDODA
3 : 568 p 628:~p In~ini~e ~:0C :
ETS
~ ~84 p 458 p Infinite 70C
ETS
W~ 2 2 ~ 2 2 ~ ~ 1 pcr/vs9~/o(~49~
-22- ~
1 ETS = Elevated Temperature Shear; RTS = Room Temperature Shear; p = All sample failures were .
panel failure , ~"-.
, " .
"~
. .:, -W~)~3~ 2 :1 ~ 2 9 2 1 PCT/US~2/094~
1 Exa~ple 3 Post Cure Coated and W -cure~ adhPsives of the present invention have better aging stability than adhesives which are made by conventional UV curing methods.
~ rawdowns of the PSAs of the present in~ention w2re subjected to an accelerated aging at 60C over a period of one week. Table v shows that the drop in the adhesive's looptack and 180 peel is only about 10~-20% from the original values. In conveQtional W -cured PSAs, losses in excess of 50% in these adhesion properties are Yery common.
~0 ", " ''~
.~.~
~,........
, ~ ~
"",''' ~'~ '', ql~2 1 ~?J 2 ~.3 21. Pcr/uss2/o949~
1 Table V
optack_and Peel Performance after One Week's Aqinq at 60C
(Adhesi~e coating weight 35 40 g/m2 on 2 mil PET film; tack, peel, and shear tests on stainless steel panels) W, kJ/m2 Looptack, N/m 180 Peel, Nlm Ini- After Ini- After 1~ tial ~g~ %~ tial Aqinq %_ 10 Pa~s. at 100C ~ -2.0% HDODA
4,5 453 403 11 467 426 ..
9 ......
5.0% HDODA
3 545 49~ 9 650 4g3 24
3 545 49~ 9 650 4g3 24
6 ~59 383 17 475 432 9 . .
~-2a 35 Pa.s. at 100C -. :
2.0% HDODA
3 556 488 l~ 572 540 6 : -6 453 392 l~ 455 ~49 : .
-~
P-2b ~ -:, .",. "
65 Pa.s. at 100~C
2~0.% HDODA . :
3 56~ 513 10 628 493 21 ~ 484 459 5 458 408 11 :.
~, In situ Incorporat_on~ o~ hotoinitiator Fun~tion ~-Polymer~3 was made :according ~o the present ~ ,!,~;
inYention. T~le phot~in:itiator material~used wa~ the alcohol DAROC~R 2959 or~4(2~-hydro~yethoxy~phenyl-(2~
hydrvxy-2-propyl)ketone,~ which ~ was :made cop~lymerizable through~ t~e maleata ~ halfester compound. The~male~te hal~est~r, however, ~was nQt made in a separat~ synkhsis~s~p, but:was~made~
W~Q~ 31~ 2' 3 ~1 fJ~r/uss~/~s~3 1 situ during the polymerization of the monomers which comprise the PsA material. The following monomers: :
57~ by weight of butylacrylate, 4~ acrylic acid, 35%
dioctylfumarate, and 2% maleic anhydride, were copolymerized in th~ presence of 2% by weight DAROCUR
2959, at gO-95C, using Vazo 52/64 as polymerization initiators. At the end of the polymerization step, the maleate halfester for~a~ion with the photoinitiator alcohol DAXOCUR 2959 was completed by ~ -.
l0 the addition of 0~25% of N,N-dimethylbenzylaminP. :-The composition of P-3 is summarized in Table VI.
Table VI
butylac:rylate 57 acrylic acid 4 dioctylfumarate 35 maleic anhydride 2 N,N-dimethylbenzylamine 0~25 -:
Vazo S2/64 polymerization :initiator HDODA, compounded a~ter polymerization 4 The product has a l00C melt viscosity of 30.4 -:
Pa.s. before compounding. Xt was subsequently ~
compounded with 4~ by weight of HDODA and after - ~ .
coating on 50 ~m poly-(ethylene terephthalate) (PET~ : :
~t a coating weight of 30 glm2 and W -cured. The adhesive performance of the PSA is summarized in Tab~e VII~
`~
. ~.
., :.- :
~, .. :.., ~
~3/~15~ JC~/~'S',)~ 49;~
h J ~.J J.
Table VII
Loop-- 180 70C
W tack Peel ETS
kJlm2 (N~m~ (N/m) (Min. ) . .
P-3 4 407 p/ps 638 c 400~+,NC
6 3~5 p 554 c/ps 4000~,NC
8 402 p 546 p 4000t,NC
c = cohesive, adhesive film splits during the test~
leaving re~idue films both on panel and fa~estock p = no visible stain on panel :
ps - visible stain on pa~el, but no sticky residue NC = no creep ..
Example 5 ;;~
Resistance to Lig~id~Immersion lSCoated and UV-cured adhesi.~es of the present in~ention exhibit good immersion resistance to a number of liquids, provided when the facestock ~ .:
m~terial is not aff~cted by t:he li~uids in the i~mersion tests.
2~Polymer P-3 was evaluated fi~r ~n under-the-hood automotive labeling adhesive application, where the labels might be exposed to a number of automo~ive -~
liquids. In this evaluation, 2.54 cm x about 20 cm -$est samples from the previous illustration were 25 applied to standard stain1ess steel test panels. .
After a ~well time of :24 hourst the panels and ~pplied test samples:were immersed in the a~tomotive -~`
liquids~ A~ter the specified times of immer~ion, the - .-panels and samples were tak~n~out. The adhering : ~.' 3~ liquîds were carefully blot~ed with filter paper:, and ,.
a~ter a l-hour recovery at ambient, t~he test strips :
were examined for:liquid:~edge penetration and for any changes to the~acestocks. ~Maximum acceptable ed~e : `
penetration is normally no more than 5~mm. :Fin~lly, ~ ~=
the test strips vere peelecl awaV in a 18~D peel ang1e ~ , .........
~V~I~J0~ 212 ~ ~ ~ t P~r/uss2/o~
1 from the test panels. The results are summarized in Tabl e VIII.
Table VIII
Changes to Facest~ck Ed~e Penetration and SPeel Measurements af~ter Exposure of APplied Labels on Stainle s StePl Panels Change to face-Cure W stoc~ and edge 180~Peel kJ/m2 ~enetration .
10 N/m 1 hour in gasoline 4 No chang~ to 764 at ambient temp. 6 facestock, 2 mm 741 8 edge penetration 64~ :
15 c ~ ~:
~ hours in 120~C 4 No change in 7~7 c , ~ .
hot engine oil 6 facestock or 738 :
. . . .
8 edge penetration 7B8 :
4 hours in brake 4 No ch~:nge in 785 -~
c .~
fluid at ambient 6 ~acestock or 775 .-;
temp. 8 edge penetration 733 c - cohesive, adhesive film splits during the test, -leaving residue films ~oth on panel and facestock . Example 6 Stable Pot-Lives of Co~unded ~ot Melt PSA:Formula~ions :
Polymer-4 was a s~al~ up uf:~:P-3 from 800:g to 6000 g. It had a lOO~C melt viscssity of 27.9 ~a.s.
before compounding. It was subs:equently compounded with 4% by weight o~ HI3ODA and~af~er co~in~ on~ 5û ,a~m PET at a coating w~ight of 30 g/m2, was W -cured. :The W~ 13~ Pcr/us92~ol~4~?s 212~2 1 1 adhesive perormance of P-4 is summarized in Table IX.
Table IX
~oop- 18~ 70C .-: ~.
W tack Peel ETS .. :-~/m2 (N/mL LNlm) lMin.) P-4 4 46~ p 701 c 4000~,NC
6 391 p 548 p 4000~,NC
8 295 p 430 p 4000+,NC
c = cohesi~e, adhesive film splits during the test, -~
: . ,,,:
leaving residue films both on panel and faces~ock.
p = no visible stain on panel.
NC = no creep.
Compounded polymers which are made according to tAe present invention have very ~ood pot-lives, even when kept at elevated ten~peratures.
The coater xeady P-4 which contained 4% by weight of HDODA was heated continuously at 100C in the Thermocell of a Brookfield vissometer, and the melt viscos~ty followed over several days. The melt viscosity rose from about 16 Pa.s. to only about 22 Paqs. after 8 days of continuous heating, after which time it rose quicker to about 2g Pa.s. after 11 days of heating. The results are presented in FIG. 3.
Example 7 Polymer 5 was made according to the pr~sent in~ention. It cont~ ined :2%~: by weight of the copolymer~izable photolnitiator~DAROCUR ZLI 3~3:31~, and consisted furthe~ of ~6% 2-ethylhexylacrylate, 24%
3~ methylacrylate, 3% acryli;c acid, ~ 7%
carboxyethylacrylate, and 8% dio~tylmaleate.~ It was suhsequently scaled up~ tQ a 100~kilogram~:batch run, which, af~er compounding wi~th 4% by weight:of~HDODA, had a 100C melt vi~cosity of~ 12.G: Pa:.s.~ The compositlon of~P-5 is su=marized in Table X.~
.,; - ,:
".. ~-,, ~ n~Js~ ~12~' 9 2 ~ PCT/VS92/094~3 :
1 Table x 2-ethylhexylacrylate 56 methyl~crylate 24 ~-carboxyethylacrylate 7 acrylic acid 3 dioctylmaleate 8 -~
DA~OCUR ZLI 3331 2 :
HDODA, compounded after polymerization 4 The scaled-up batch had the following adhesive ~ :
p~r ormance on 50 ~m PET facestock at a coating ~: :
}0 weight of 30 g/m2 and after W cure. The properties of P 5 are summaxizad in Table XI. `:
~able_XI
Loop- 1~0 70C .
W tack Peel ~TS
~ L~L ~N/m) ~n-) 15 Scal~d-up ~:
p-5 4 507 p 663 c 1200+,N~
6 520 p 677 p/c 1200+,NC
8 575 p 603 p~c 1200+,NC
c = cohesive, adhesive film sp:Lits during the test, leaviny residue films both on panel and ~0 facestock -~-p = no visible stain on panel ~:
NC = no creep :~
The scaled up, P-5 coater-ready material was stored in closed, l9-liter~ metal pails, and was `
retrieved after lo :months of stor~ge under uncontroll~d warehouse conditians~ The material had ~ `~
an xcellent ~helf-life. The 100C melt viscosity rose only to 12.3 Pa~s~ `after:the lO-mon~h stora~e period~ The material:~was still very W -reactive;
after coating on 50 ~m PET at~30 g/m2~coatlng weight and W cure wlth only 4 kJ/m2, it gave infinite 70~C -~
ETS, without a~y creep~
'Solu~
The form~tion~f:high cohes:ive stren ffl h~in P~SAs by W cure ~of~ the~present; invention~ is~also W~ 9~/~gl~9 2 1 2 ~ S 2 1 ~cr/usg2~Q(>49~
1 a~plicabl~ to solution-based as well as emulsion- :~
based adhesives. .
Pol~mer-6 was made in ethylacetate solution from 52.5% by weight of 2-ethylhexylacrylate, 18% methyl-acryla~e, 18% vinylacetate, ~% dioctylmal~ate, 3%
acrylic acid, and 0.5% DAROCUR ZLI 3331, using Vazo 52 as th~ pol~merization initiator. The ~omposition o~ P-6 is summarized in Table XII. .
Table XII ~ ~.
2 ethylhexylacrylate 52.5 methylacrylate 18 vinylacetate 18 .
ac:rylic acid 3 ~ :.
dioctylmaleate DAROCUR ZLI 3331 0.5 .
HDODA, compounded after polymerization 4 A portion of the product was evaporated to dryness; it had a 100C melt viscosity of 136.0 Pa.s.
The remainder of the product was subsequently compounded with 4% by weight of HDODA based on the ~.
2~ polymer solids. W cure de~eloped high cohesive -strength in the adhesive coating on 50 ~m PET at a dry coating weight of 30 g/m2. The properties of P-6 `.:~
are summarized in Tahle XIII.
Tahle XII
~5 ~ p ~0O 70C ~:~
UV tacX Peel ETS . :.
~ LmL ~Lm~ (Min.
P-6 0 770 p 666 c O G :.
4 424 p 71~ ps1200+,~C
6 358 p 501 p/c1200+,N~
8 380 p 381 p1200~,NC . .:
c = cohesive, adhesive film splits during the test, :~
lea~in~ residue f ilms both on panel and ~ ;
f acestock p = no vi~i~le stain on panel ps - visible stain on panel, but no stic3~y residue . :
NC -- no creep ... .
'` ' ',' :, :-~ 15~ 2 1 2 ~' 9 2 1 ~T~US92/0949~
. ~ , `li~ , ! ' ExamPle 9 Polymer-7 was made in emulsion and consisted of 55% by weight of 2-ethylhexylacrylate, 20% methyl-acrylate, 8% dioctylmalea~e, 5% acrylic acid, and 1%
5 of DAROCUR ZLI 3331, using Alipal C0-436 .
(manu~actured by Rhone Poulenc/Triton X-165 (manufactured by Union Carbide) as the surfactant, and t-butylhydroperoxide-FeE~TA as the redox initiator system. The product was compounded with 4%
by w ight of HDODA based on polymer solids. The composition of P-7 is summari2ed in Table XIV.
~able XIV
2-ethylhexylacrylate 66 methylacrylate 20 acrylic acid 5 ~5 dioctylmaleate HDODA, compounded after polymerizat.ion 4 W cure developed high cohesive strength in the adhesive coating, on 5Q ~m PET a-t a coating weight of 30 g/m2~ The properties of P-7 are summarized in Table XY.
able XV
Loop- 180 70C
W tack Peel ETS :
k~/m2 lN/m~ ~N/m) ~Min~L -~
P-7 ~ 244 p 267 c~p~ O c 6 135 p 50 p 1200~,NC
8 137 p 49 p 12QO+,NC
c = cohesive, ~dhesiv film ~plits during the test, leaving residue films b~th on panel and .::
3 o fa~estock p ~ no visibl~ sta i n on panel :~
ps = visible stain on panel, but no stic~y ~esidue . ::~
NC - no creep ~ ;
,;.,`,~
;. ....
~-2a 35 Pa.s. at 100C -. :
2.0% HDODA
3 556 488 l~ 572 540 6 : -6 453 392 l~ 455 ~49 : .
-~
P-2b ~ -:, .",. "
65 Pa.s. at 100~C
2~0.% HDODA . :
3 56~ 513 10 628 493 21 ~ 484 459 5 458 408 11 :.
~, In situ Incorporat_on~ o~ hotoinitiator Fun~tion ~-Polymer~3 was made :according ~o the present ~ ,!,~;
inYention. T~le phot~in:itiator material~used wa~ the alcohol DAROC~R 2959 or~4(2~-hydro~yethoxy~phenyl-(2~
hydrvxy-2-propyl)ketone,~ which ~ was :made cop~lymerizable through~ t~e maleata ~ halfester compound. The~male~te hal~est~r, however, ~was nQt made in a separat~ synkhsis~s~p, but:was~made~
W~Q~ 31~ 2' 3 ~1 fJ~r/uss~/~s~3 1 situ during the polymerization of the monomers which comprise the PsA material. The following monomers: :
57~ by weight of butylacrylate, 4~ acrylic acid, 35%
dioctylfumarate, and 2% maleic anhydride, were copolymerized in th~ presence of 2% by weight DAROCUR
2959, at gO-95C, using Vazo 52/64 as polymerization initiators. At the end of the polymerization step, the maleate halfester for~a~ion with the photoinitiator alcohol DAXOCUR 2959 was completed by ~ -.
l0 the addition of 0~25% of N,N-dimethylbenzylaminP. :-The composition of P-3 is summarized in Table VI.
Table VI
butylac:rylate 57 acrylic acid 4 dioctylfumarate 35 maleic anhydride 2 N,N-dimethylbenzylamine 0~25 -:
Vazo S2/64 polymerization :initiator HDODA, compounded a~ter polymerization 4 The product has a l00C melt viscosity of 30.4 -:
Pa.s. before compounding. Xt was subsequently ~
compounded with 4~ by weight of HDODA and after - ~ .
coating on 50 ~m poly-(ethylene terephthalate) (PET~ : :
~t a coating weight of 30 glm2 and W -cured. The adhesive performance of the PSA is summarized in Tab~e VII~
`~
. ~.
., :.- :
~, .. :.., ~
~3/~15~ JC~/~'S',)~ 49;~
h J ~.J J.
Table VII
Loop-- 180 70C
W tack Peel ETS
kJlm2 (N~m~ (N/m) (Min. ) . .
P-3 4 407 p/ps 638 c 400~+,NC
6 3~5 p 554 c/ps 4000~,NC
8 402 p 546 p 4000t,NC
c = cohesive, adhesive film splits during the test~
leaving re~idue films both on panel and fa~estock p = no visible stain on panel :
ps - visible stain on pa~el, but no sticky residue NC = no creep ..
Example 5 ;;~
Resistance to Lig~id~Immersion lSCoated and UV-cured adhesi.~es of the present in~ention exhibit good immersion resistance to a number of liquids, provided when the facestock ~ .:
m~terial is not aff~cted by t:he li~uids in the i~mersion tests.
2~Polymer P-3 was evaluated fi~r ~n under-the-hood automotive labeling adhesive application, where the labels might be exposed to a number of automo~ive -~
liquids. In this evaluation, 2.54 cm x about 20 cm -$est samples from the previous illustration were 25 applied to standard stain1ess steel test panels. .
After a ~well time of :24 hourst the panels and ~pplied test samples:were immersed in the a~tomotive -~`
liquids~ A~ter the specified times of immer~ion, the - .-panels and samples were tak~n~out. The adhering : ~.' 3~ liquîds were carefully blot~ed with filter paper:, and ,.
a~ter a l-hour recovery at ambient, t~he test strips :
were examined for:liquid:~edge penetration and for any changes to the~acestocks. ~Maximum acceptable ed~e : `
penetration is normally no more than 5~mm. :Fin~lly, ~ ~=
the test strips vere peelecl awaV in a 18~D peel ang1e ~ , .........
~V~I~J0~ 212 ~ ~ ~ t P~r/uss2/o~
1 from the test panels. The results are summarized in Tabl e VIII.
Table VIII
Changes to Facest~ck Ed~e Penetration and SPeel Measurements af~ter Exposure of APplied Labels on Stainle s StePl Panels Change to face-Cure W stoc~ and edge 180~Peel kJ/m2 ~enetration .
10 N/m 1 hour in gasoline 4 No chang~ to 764 at ambient temp. 6 facestock, 2 mm 741 8 edge penetration 64~ :
15 c ~ ~:
~ hours in 120~C 4 No change in 7~7 c , ~ .
hot engine oil 6 facestock or 738 :
. . . .
8 edge penetration 7B8 :
4 hours in brake 4 No ch~:nge in 785 -~
c .~
fluid at ambient 6 ~acestock or 775 .-;
temp. 8 edge penetration 733 c - cohesive, adhesive film splits during the test, -leaving residue films ~oth on panel and facestock . Example 6 Stable Pot-Lives of Co~unded ~ot Melt PSA:Formula~ions :
Polymer-4 was a s~al~ up uf:~:P-3 from 800:g to 6000 g. It had a lOO~C melt viscssity of 27.9 ~a.s.
before compounding. It was subs:equently compounded with 4% by weight o~ HI3ODA and~af~er co~in~ on~ 5û ,a~m PET at a coating w~ight of 30 g/m2, was W -cured. :The W~ 13~ Pcr/us92~ol~4~?s 212~2 1 1 adhesive perormance of P-4 is summarized in Table IX.
Table IX
~oop- 18~ 70C .-: ~.
W tack Peel ETS .. :-~/m2 (N/mL LNlm) lMin.) P-4 4 46~ p 701 c 4000~,NC
6 391 p 548 p 4000~,NC
8 295 p 430 p 4000+,NC
c = cohesi~e, adhesive film splits during the test, -~
: . ,,,:
leaving residue films both on panel and faces~ock.
p = no visible stain on panel.
NC = no creep.
Compounded polymers which are made according to tAe present invention have very ~ood pot-lives, even when kept at elevated ten~peratures.
The coater xeady P-4 which contained 4% by weight of HDODA was heated continuously at 100C in the Thermocell of a Brookfield vissometer, and the melt viscos~ty followed over several days. The melt viscosity rose from about 16 Pa.s. to only about 22 Paqs. after 8 days of continuous heating, after which time it rose quicker to about 2g Pa.s. after 11 days of heating. The results are presented in FIG. 3.
Example 7 Polymer 5 was made according to the pr~sent in~ention. It cont~ ined :2%~: by weight of the copolymer~izable photolnitiator~DAROCUR ZLI 3~3:31~, and consisted furthe~ of ~6% 2-ethylhexylacrylate, 24%
3~ methylacrylate, 3% acryli;c acid, ~ 7%
carboxyethylacrylate, and 8% dio~tylmaleate.~ It was suhsequently scaled up~ tQ a 100~kilogram~:batch run, which, af~er compounding wi~th 4% by weight:of~HDODA, had a 100C melt vi~cosity of~ 12.G: Pa:.s.~ The compositlon of~P-5 is su=marized in Table X.~
.,; - ,:
".. ~-,, ~ n~Js~ ~12~' 9 2 ~ PCT/VS92/094~3 :
1 Table x 2-ethylhexylacrylate 56 methyl~crylate 24 ~-carboxyethylacrylate 7 acrylic acid 3 dioctylmaleate 8 -~
DA~OCUR ZLI 3331 2 :
HDODA, compounded after polymerization 4 The scaled-up batch had the following adhesive ~ :
p~r ormance on 50 ~m PET facestock at a coating ~: :
}0 weight of 30 g/m2 and after W cure. The properties of P 5 are summaxizad in Table XI. `:
~able_XI
Loop- 1~0 70C .
W tack Peel ~TS
~ L~L ~N/m) ~n-) 15 Scal~d-up ~:
p-5 4 507 p 663 c 1200+,N~
6 520 p 677 p/c 1200+,NC
8 575 p 603 p~c 1200+,NC
c = cohesive, adhesive film sp:Lits during the test, leaviny residue films both on panel and ~0 facestock -~-p = no visible stain on panel ~:
NC = no creep :~
The scaled up, P-5 coater-ready material was stored in closed, l9-liter~ metal pails, and was `
retrieved after lo :months of stor~ge under uncontroll~d warehouse conditians~ The material had ~ `~
an xcellent ~helf-life. The 100C melt viscosity rose only to 12.3 Pa~s~ `after:the lO-mon~h stora~e period~ The material:~was still very W -reactive;
after coating on 50 ~m PET at~30 g/m2~coatlng weight and W cure wlth only 4 kJ/m2, it gave infinite 70~C -~
ETS, without a~y creep~
'Solu~
The form~tion~f:high cohes:ive stren ffl h~in P~SAs by W cure ~of~ the~present; invention~ is~also W~ 9~/~gl~9 2 1 2 ~ S 2 1 ~cr/usg2~Q(>49~
1 a~plicabl~ to solution-based as well as emulsion- :~
based adhesives. .
Pol~mer-6 was made in ethylacetate solution from 52.5% by weight of 2-ethylhexylacrylate, 18% methyl-acryla~e, 18% vinylacetate, ~% dioctylmal~ate, 3%
acrylic acid, and 0.5% DAROCUR ZLI 3331, using Vazo 52 as th~ pol~merization initiator. The ~omposition o~ P-6 is summarized in Table XII. .
Table XII ~ ~.
2 ethylhexylacrylate 52.5 methylacrylate 18 vinylacetate 18 .
ac:rylic acid 3 ~ :.
dioctylmaleate DAROCUR ZLI 3331 0.5 .
HDODA, compounded after polymerization 4 A portion of the product was evaporated to dryness; it had a 100C melt viscosity of 136.0 Pa.s.
The remainder of the product was subsequently compounded with 4% by weight of HDODA based on the ~.
2~ polymer solids. W cure de~eloped high cohesive -strength in the adhesive coating on 50 ~m PET at a dry coating weight of 30 g/m2. The properties of P-6 `.:~
are summarized in Tahle XIII.
Tahle XII
~5 ~ p ~0O 70C ~:~
UV tacX Peel ETS . :.
~ LmL ~Lm~ (Min.
P-6 0 770 p 666 c O G :.
4 424 p 71~ ps1200+,~C
6 358 p 501 p/c1200+,N~
8 380 p 381 p1200~,NC . .:
c = cohesive, adhesive film splits during the test, :~
lea~in~ residue f ilms both on panel and ~ ;
f acestock p = no vi~i~le stain on panel ps - visible stain on panel, but no stic3~y residue . :
NC -- no creep ... .
'` ' ',' :, :-~ 15~ 2 1 2 ~' 9 2 1 ~T~US92/0949~
. ~ , `li~ , ! ' ExamPle 9 Polymer-7 was made in emulsion and consisted of 55% by weight of 2-ethylhexylacrylate, 20% methyl-acrylate, 8% dioctylmalea~e, 5% acrylic acid, and 1%
5 of DAROCUR ZLI 3331, using Alipal C0-436 .
(manu~actured by Rhone Poulenc/Triton X-165 (manufactured by Union Carbide) as the surfactant, and t-butylhydroperoxide-FeE~TA as the redox initiator system. The product was compounded with 4%
by w ight of HDODA based on polymer solids. The composition of P-7 is summari2ed in Table XIV.
~able XIV
2-ethylhexylacrylate 66 methylacrylate 20 acrylic acid 5 ~5 dioctylmaleate HDODA, compounded after polymerizat.ion 4 W cure developed high cohesive strength in the adhesive coating, on 5Q ~m PET a-t a coating weight of 30 g/m2~ The properties of P-7 are summarized in Table XY.
able XV
Loop- 180 70C
W tack Peel ETS :
k~/m2 lN/m~ ~N/m) ~Min~L -~
P-7 ~ 244 p 267 c~p~ O c 6 135 p 50 p 1200~,NC
8 137 p 49 p 12QO+,NC
c = cohesive, ~dhesiv film ~plits during the test, leaving residue films b~th on panel and .::
3 o fa~estock p ~ no visibl~ sta i n on panel :~
ps = visible stain on panel, but no stic~y ~esidue . ::~
NC - no creep ~ ;
,;.,`,~
;. ....
Claims (20)
1. A pressure-sensitive adhesive copolymer formed by applying a hot melt coating of a mixture of a copolymer of:
a. at least one copolymerizable photoinitiator acyloin monomer; and b. at least one low-glass-transition-temperature monomer present in an amount sufficient to provide a copolymer having a Tg of at least about 50°C below the use temperature with;
c. at least one multifunctional monomer selected from the group consisting of multifunctional acrylates, methacrylates and mixtures thereof, and exposing said mixture to actinic radiation at with light at about 240 to about 410 nm wavelength at a light intensity of about 6 to about 10 kWatts/m2, and at a temperature of about 45°C to about 125°C under aerobic conditions to form a cured pressure-sensitive adhesive having a cohesive strength and a high-temperature shear strength of at least several thousand minutes; a tack of about 300 to about 500 N/m; a peel adhesion of about 550 to about 660 N/m;
said mixture prior to aerobic cure having a shelf-life at room temperature of more than about 10 months, with no increase in the viscosity of the polymer; and a hot melt pot-life at 100°C of at least 10 days, with little or substantially no increase in the viscosity of the polymer.
a. at least one copolymerizable photoinitiator acyloin monomer; and b. at least one low-glass-transition-temperature monomer present in an amount sufficient to provide a copolymer having a Tg of at least about 50°C below the use temperature with;
c. at least one multifunctional monomer selected from the group consisting of multifunctional acrylates, methacrylates and mixtures thereof, and exposing said mixture to actinic radiation at with light at about 240 to about 410 nm wavelength at a light intensity of about 6 to about 10 kWatts/m2, and at a temperature of about 45°C to about 125°C under aerobic conditions to form a cured pressure-sensitive adhesive having a cohesive strength and a high-temperature shear strength of at least several thousand minutes; a tack of about 300 to about 500 N/m; a peel adhesion of about 550 to about 660 N/m;
said mixture prior to aerobic cure having a shelf-life at room temperature of more than about 10 months, with no increase in the viscosity of the polymer; and a hot melt pot-life at 100°C of at least 10 days, with little or substantially no increase in the viscosity of the polymer.
2. A pressure-sensitive adhesive copolymer as claimed in claim 1 in which the copolymerizable photoinitiator is an acyloin monomer and in which the low-glass-transition-temperature monomer comprises and acrylic monomer provided in an amount sufficient to provide a cured polymer having a Tg of at least about 50°C below use temperature.
3. A pressure-sensitive adhesive copolymer as claimed in claim 1 wherein the low-glass-transition-temperature monomer is selected from the group consisting of 2-ethylhexyacrylate, iso-octylacryate, butylacrylate, and mixtures thereof.
4. A pressure-sensitive adhesive copolymer as claimed in claim 1,2 or 3 wherein the copolymeriz-able photoinitiator monomer is selected from the group consisting of 4(2-acryloyloxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone and 4(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone.
5. A pressure-sensitive adhesive copolymer as claimed in any one of the previous claims wherein the copolymerizable photoinitiator monomer is present at a concentration of about 0.1% to about 10% by weight.
6. A pressure-sensitive adhesive copolymer as claimed in any one of the previous claims wherein the copolymerizable photoinitiator monomer is present at a concentration of about 0.5% to about 5% by weight.
7. A pressure-sensitive adhesive copolymer as claimed in any one of the previous claims wherein the multifunctional monomer is are selected from the group consisting of diethylene-glycoldiacrylate, tri-ethylaneglycol-diacrylate, tripropylencglycoldi-acrylate, 1,6-hexanedioldiacrylate, trimethylolpro-panetriacrylate, trimethylolpropanetrimethacrylate, pentaerythritoltriacrylate, and mixtures thereof.
8. A pressure-sensitive adhesive copolymer as claimed in any one of the previous claims wherein the multifunctional monomer is present at a concentration of about 0.1% to about 10% by weight.
9. A pressure-sensitive adhesive copolymer as claimed in any one of claims 1 to 7 wherein the multifunctional monomer is present at a concentration of about 1% to about 5% by weight.
10. A pressure-sensitive adhesive copolymer as claimed in any one of the previous claims wherein the light is supplied by medium-pressure mercury lamps.
11. A process for preparing a pressure-sensi-tive adhesive copolymer suitable for the preparation of hot melts comprising:
a) copolymerizing at least one low glass-transition-temperature monomer in an amount suffi-cient to provide a polymer having a Tg as low as about 50°C below the use temperature, at least one copolymerizable photoinitiator monomer selected is a benzoin compounds; acyloin compounds, their deriva-tives and mixtures thereof, and a polymerization initiator;
b) heating the polymerization mixture to maintain the polymerization reaction;
c) adding at least one multifunctional monomer to the copolymer;
d) coating the copolymer onto a suitable surface; and e) curing the coated copolymer with light at about 240 to about 410 nm wavelength, a light intensity of about 6 to about 10 kWatts/m2, and at a temperature of about 45°C to about 125°C under aerobic conditions.
a) copolymerizing at least one low glass-transition-temperature monomer in an amount suffi-cient to provide a polymer having a Tg as low as about 50°C below the use temperature, at least one copolymerizable photoinitiator monomer selected is a benzoin compounds; acyloin compounds, their deriva-tives and mixtures thereof, and a polymerization initiator;
b) heating the polymerization mixture to maintain the polymerization reaction;
c) adding at least one multifunctional monomer to the copolymer;
d) coating the copolymer onto a suitable surface; and e) curing the coated copolymer with light at about 240 to about 410 nm wavelength, a light intensity of about 6 to about 10 kWatts/m2, and at a temperature of about 45°C to about 125°C under aerobic conditions.
12. The process as claimed in claim 11 wherein the low-glass-transition-temperature monomers are selected from the group consisting of 2-ethylhexy-acrylate, isooctyl acrylate, butylacrylate and mixtures thereof.
13. The process as claimed in claim 11 or 12 wherein the copolymerizable photoinitiator monomers are selected from the group consisting of benzoin compounds, acyloin compounds, and mixtures thereof.
14. The process as claimed in any one of claims 11 to 13 wherein the copolymerizable photoinitiator monomers are selected from the group consisting of 4(2-acryloyloxyethoxy)phenyl-(2-hydroxy-2propyl)-ketone and 4(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone.
15. The process as claimed in any of claims 11 to 14 wherein the copolymerizable photoinitiator monomers are present at a concentration of about 0.1%
to about 10% by weight.
to about 10% by weight.
16. The process as claimed in any one of claims 11 to 15 wherein the copolymerizable photoinitiator monomers are present at A concentration of about 0.5%
to about 5% by weight.
to about 5% by weight.
17. The process as claimed in any one of claims 11 to 16 wherein the multifunctional monomers are selected from the group consisting of diethylene-glycoldiacrylate, triethylene-glycoldiacrylate, tripropyleneglycoldiacrylate, 1,6-hexanedioldi-acrylate, trimethylolpropanetriacrylate, trimethylol-propanetrimethacrylate, pentaerythritoltriacrylate, and mixtures thereof.
18. The process as claimed in any one of claims 11 to 17 wherein the multifunctional monomers are present at a concentration of about 0.1% to about 10%
by weight.
by weight.
19. The process as claimed in any one of claims 11 to 18 wherein the multifunctional monomers are present at a concentration of about 1% to about 5% by weight.
20. The process as claimed in any one of claims 11 to 19 wherein the light is supplied by medium-pressure mercury lamps.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US78815891A | 1991-11-05 | 1991-11-05 | |
| US788,158 | 1991-11-05 | ||
| PCT/US1992/009493 WO1993009152A1 (en) | 1991-11-05 | 1992-11-04 | Uv-cured hot melt pressure-sensitive adhesives |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2122921A1 true CA2122921A1 (en) | 1993-05-13 |
Family
ID=25143624
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002122921A Abandoned CA2122921A1 (en) | 1991-11-05 | 1992-11-04 | Uv-cured hot melt pressure-sensitive adhesives |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU3126993A (en) |
| CA (1) | CA2122921A1 (en) |
| WO (1) | WO1993009152A1 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4222334A1 (en) * | 1992-07-08 | 1994-01-13 | Beiersdorf Ag | Hot melt pressure sensitive adhesive for medical products |
| DE4406977C2 (en) * | 1994-03-03 | 1996-05-02 | Lohmann Gmbh & Co Kg | Process for the production of thick pressure-sensitive adhesive layers for the production of self-adhesive high-performance adhesive articles |
| JP3545414B2 (en) * | 1994-07-29 | 2004-07-21 | ミネソタ マイニング アンド マニュファクチャリング カンパニー | Syrup curable into crosslinked viscoelastic polymer materials |
| CA2211130A1 (en) * | 1995-02-10 | 1996-08-15 | The Minnesota Mining & Manufacturing Company | Process for the production of an article coated with a crosslinked pressure sensitive adhesive |
| US5891530A (en) * | 1996-04-19 | 1999-04-06 | Minnesota Mining And Manufacturing Company | Method for producing a coating |
| JP2000161444A (en) * | 1998-11-25 | 2000-06-16 | Xerox Corp | Puzzle cut connection device using ultraviolet curing method |
| DE50009033D1 (en) * | 1999-04-14 | 2005-01-27 | Basf Ag | Method for bonding a UV-transparent film with another substrate |
| DE10049669A1 (en) † | 2000-10-06 | 2002-04-11 | Tesa Ag | Process for the production of crosslinked acrylic hotmelt PSAs |
| WO2003046031A1 (en) | 2001-11-24 | 2003-06-05 | Tesa Ag | 2-component crosslink of end-functionalized polyacrylates |
| DE10310889A1 (en) * | 2003-03-11 | 2004-09-23 | Basf Ag | Adhesive composition useful for self-adhesive film, comprises a polymer prepared from radically polymerizable compounds and compounds having ethylenically unsaturated radically polymerizable groups and mol. wt. of less than 5000 g/mol |
| EP1791884B1 (en) | 2004-09-09 | 2011-08-10 | Tesa Se | Functionalised polymers or contact adhesive masses |
| JP5464798B2 (en) | 2007-11-08 | 2014-04-09 | 日本カーバイド工業株式会社 | Adhesive composition and optical film |
| DE102009007589A1 (en) * | 2009-02-05 | 2010-08-12 | Tesa Se | Transfer-pressure-sensitive adhesive tape and method for producing a pressure-sensitive adhesive tape |
| CN105246922B (en) | 2013-03-29 | 2019-03-08 | 亚什兰许可和知识产权有限公司 | Ultraviolet solidifiable contact adhesive |
| JP2015092003A (en) * | 2015-02-10 | 2015-05-14 | スリーエム イノベイティブ プロパティズ カンパニー | Method for producing acrylic pressure-sensitive adhesive |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3926639A (en) * | 1971-11-18 | 1975-12-16 | Sun Chemical Corp | Photopolymerizable compositions comprising polycarboxysubstituted benzophenone reaction products |
| DE2443414C2 (en) * | 1974-09-11 | 1983-05-19 | Beiersdorf Ag, 2000 Hamburg | Process for the manufacture of self-adhesive products |
| US4737559A (en) * | 1986-05-19 | 1988-04-12 | Minnesota Mining And Manufacturing Co. | Pressure-sensitive adhesive crosslinked by copolymerizable aromatic ketone monomers |
| EP0258719A3 (en) * | 1986-08-30 | 1989-07-05 | Ciba-Geigy Ag | Two-layer system |
| JP2604453B2 (en) * | 1988-12-14 | 1997-04-30 | 積水化学工業株式会社 | Acrylic adhesive tape |
-
1992
- 1992-11-04 WO PCT/US1992/009493 patent/WO1993009152A1/en active Application Filing
- 1992-11-04 AU AU31269/93A patent/AU3126993A/en not_active Abandoned
- 1992-11-04 CA CA002122921A patent/CA2122921A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| AU3126993A (en) | 1993-06-07 |
| WO1993009152A1 (en) | 1993-05-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |