Acrylic syrup curable to a crosslinked viscoelastomeric material

• US 5,902,836 A
• Filed: 08/23/1995
• Issued: 05/11/1999
• Est. Priority Date: 07/29/1994
• Status: Expired due to Term

• Current Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Zimmerman, Patrick G., Chen, Kejian, Vesley, George F., Bennett, Greggory S., Winslow, Louis E., Babu, Gaddam N.
• Primary Examiner(s): Berman, Susan W.
• Application Number:
  US08/505,350
• Time in Patent Office: 1,357 Days
• Field of Search: 522/904, 522/905, 522/35, 522/182, 522/114, 522/121, 522/125, 522/8, 522/34, 526/328.5, 526/328
• US Class Current: 522/8
• CPC Class Codes: C08F 2/02 Polymerisation in bulk
• CPC Class Codes: C08F 2/48 by ultraviolet or visible light
• CPC Class Codes: C08F 2/50 with sensitising agents
• CPC Class Codes: C08F 265/00 Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00
• CPC Class Codes: C08F 291/00 Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00
• CPC Class Codes: C09D 4/06 Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09D159/00 - C09D187/00
• CPC Class Codes: C09J 4/06 Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
• CPC Class Codes: G03F 7/027 Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds G03F7/075 takes precedence
• CPC Class Codes: Y10S 522/904 Monomer or polymer contains initiating group
• CPC Class Codes: Y10S 522/905 Benzophenone group

Abstract

Solute polymers in solvent monomers form a coatable syrup that can be cured to a viscoelastomeric material when radiation-sensitive α-cleaving groups in either the polymer or one of the monomers are exposed to ultraviolet radiation. The solute polymers can be formed from the solvent monomers in situ or be added thereto to form the syrup.

Claims

1. A syrup curable to a crosslinked viscoelastomeric adhesive comprising:

a) about 85 to 99.9 weight percent of a solvent monomer mixture comprising

1) 95 to 100 parts by weight of at least one free radically-polymerizable ethylenically unsaturated monomer, and

2) an ethylenically unsaturated monomer in an amount up to 5 parts by weight and comprising a radiation-sensitive α

-cleaving group;

b) about 0.1 to 15 weight percent of a solute polymer prepared in situ from said monomer mixture;

c) from 0 to 5 parts by weight of a free radically-polymerizable polyethylenically unsaturated monomer; and

d) from 0 to 3 parts by weight of a saturated energy-activated initiator of polymerization.

2. The syrup of claim 1 wherein said at least one free radically-polymerizable ethylenically unsaturated monomer of said monomer mixture comprises a monoethylenically unsaturated monomer homopolymerizable to a polymer having a glass transition temperature of less than about 0°

C.

3. The syrup of claim 2 wherein said monoethylenically unsaturated monomer is selected from the group consisting of isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, decyl acrylate, dodecyl acrylate, hexyl acrylate, and butyl acrylate.

4. The syrup of claim 2 wherein said at least one free radically-polymerizable ethylenically unsaturated monomer further comprises a monoethylenically unsaturated monomer homopolymerizable to a polymer having a glass transition temperature of greater than about 50°

C.

5. The syrup of claim 4 wherein said second monoethylenically unsaturated monomer is selected from the group consisting of (meth)acrylic acid, itaconic acid, N,N-dimethylacrylamide, N-octylacrylamide, 2-hydroxyethyl acrylate, N-vinyl pyrrolidone, N-vinyl caprolactam, acrylonitrile, tetrahydrofurfuryl acrylate, and isobornyl acrylate.

6. The syrup of claim 1 wherein said ethylenically unsaturated monomer comprising a radiation sensitive group has the formula ##STR7## wherein R is H or a C₁ to C₃ alkyl group, preferably H or a methyl group;

X is O or NH;

n is 0 or 1;

m is 0 or an integer from 1 to 5;

a, b, and c are independently 0 or 1;

M¹ is CH₂ or SiR¹ R² ;

M² is CR³ R⁴ or SiR¹ R² ;

M³ is O, NH, C(O), C(O)O, C(O)NH, or OC(O)NH;

R¹ and R² are independently H or a C₁ to C₄ alkyl group;

R³ and R⁴ are independently H, an alkyl group having 1 to 14 carbon atoms, a cycloalkyl group having 3 to 14 carbon atoms, an aryl group having 5 to 12 ring atoms, an arenyl group having 6 to 26 carbon and 0 to 3 S, N, and nonperoxidic O heteroatoms, or R³ and R⁴ taken together with the carbon to which they are attached form a carbocyclic ring containing 4 to 12 ring atoms;

G is a covalent bond, (CH₂)_d, or (CH₂)_d O where d is an integer from 1 to 4, preferably from 1 to 2;

Z is a radiation-sensitive α

-cleaving group having the general formula ##STR8## in which Ar is an arene group having 6 to 12 carbon atoms and substituted by R⁵ ;

R⁵ is hydrogen, a C₁ to C₁₂ alkyl group, a C₁ to C₁₂ alkoxy group, or a phenyl group; and

R⁹ is selected from the group consisting of ##STR9## in which R⁴ is selected from the class consisting of hydrogen, C₁ to C₁₂ alkyl groups, C₁ to C₁₂ alkoxy groups, and phenyl groups, with the proviso that, when R³ and R⁵ are both ortho to the carbonyl group of Z, together they can be one of ##STR10## and R⁶, R⁷, and R⁸ are independently selected from the class consisting of hydroxyl, phenyl, C₁ to C₁₂ alkyl, C₁ to C₆ alkoxy, and --NR¹⁰ R¹¹ groups, wherein R¹⁰ and R¹¹ are independently hydrogen or a C₁ to C₆ alkyl group,

with the proviso that, when R⁹ is --CR⁶ R⁷ R⁸, one of the following must be true;

(1) at least one of R⁶, R⁷, and R⁸ is selected from the class consisting of hydroxyl, alkoxy, and --NR¹⁰ R¹¹ ;

(2) any two of R⁶, R⁷, and R⁸ together are one of --C_p H_2p -- and --OC_p H_2p O-- wherein p is either 2 or 3 so that they, together with the carbon atoms to which they are attached, form a 5- or 6-membered ring; and

(3) any two of R⁶, R⁷, and R⁸ together are a carbonyl group, provided that the remaining one of R⁶, R⁷, and R⁸ is selected from the class consisting of hydroxy, alkoxy, --NR¹⁰ R¹¹, and phenyl groups.

7. The syrup of claim 6 wherein R⁹ of said ethylenically unsaturated monomer comprising a radiation-sensitive group is ##STR11##

8. The syrup of claim 6 wherein X is O, m is 0, and G is (CH₂)_d O with d being 2.

9. The syrup of claim 6 wherein Ar of said ethylenically unsaturated monomer comprising a radiation-sensitive α

-cleaving group is a benzene group.

10. The syrup of claim 1 wherein said saturated energy-activated initiator of polymerization is present in an amount of 0.001 to 1.0 parts by weight.

11. The syrup of claim 1 wherein said solute polymer has a molecular weight of at least 500,000.

12. The syrup of claim 10 wherein said energy is ultraviolet radiation.

13. The syrup of claim 1 wherein said syrup is of a coatable viscosity.

14. A process for making a viscoelastomeric adhesive comprising the steps:

a) providing a composition comprising

1) a solvent monomer mixture comprising

(a) at least one free radically-polymerizable ethylenically unsaturated monomer, and

(b) an ethylenically unsaturated monomer in an amount up to 5 parts by weight and comprising a radiation-sensitive α

-cleaving group, and

2) 0 to 3 parts by weight of a saturated energy-activated initiator of polymerization;

b) exposing said composition to energy so as to partially polymerize said monomer mixture to form a coatable adhesive syrup;

c) adding to said syrup, based on the total amount of monomer initially present in said monomer mixture,

1) 0 to 3 parts by weight of a saturated energy-activated initiator of polymerization,

2) 0 to 3 parts by weight of an ethylenically unsaturated monomer comprising a radiation-sensitive α

-cleaving group, with the proviso that the amount of ethylenically unsaturated monomer comprising a radiation-sensitive α

-cleaving group added to said syrup must be greater than zero when the amount of said ethylenically unsaturated monomer comprising a radiation-sensitive α

-cleaving group in said monomer mixture is zero, and

3) 0 to 5 parts by weight of a free radically-polymerizable polyethylenically unsaturated monomer; and

d) exposing said syrup to energy that activates said saturated initiator and said radiation-sensitive α

-cleaving group of said ethylenically unsaturated monomer comprising a radiation-sensitive α

-cleaving group so as to form said viscoelastomeric adhesive.

15. The process of claim 14 wherein said ethylenically unsaturated monomer comprising a radiation-sensitive α

-cleaving group has the formula ##STR12## wherein R is H or a C₁ to C₃ alkyl group, preferably H or a methyl group;

X is O or NH;

n is 0 or 1;

m is 0 or an integer from 1 to 5;

a, b, and c are independently 0 or 1;

M¹ is CH₂ or SiR¹ R² ;

M² is CR³ R⁴ or SiR¹ R² ;

M³ is O, NH, C(O), C(O)O, C(O)NH, or OC(O)NH;

R¹ and R² are independently H or a C₁ to C₄ alkyl group;

R³ and R⁴ are independently H, an alkyl group having 1 to 14 carbon atoms, a cycloalkyl group having 3 to 14 carbon atoms, an aryl group having 5 to 12 ring atoms, an arenyl group having 6 to 26 carbon and 0 to 3 S, N, and nonperoxidic O heteroatoms, or R³ and R⁴ taken together with the carbon to which they are attached form a carbocyclic ring containing 4 to 12 ring atoms;

G is a covalent bond, (CH₂)_d, or (CH₂)_d O where d is an integer from 1 to 4, preferably from 1 to 2;

Z is a radiation-sensitive α

-cleaving group having the general formula ##STR13## in which Ar is an arene group having 6 to 12 carbon atoms and substituted by R⁵ ;

R⁵ is hydrogen, a C₁ to C₁₂ alkyl group, a C₁ to C₁₂ alkoxy group, or a phenyl group; and

R⁹ is selected from the group consisting of ##STR14## in which R⁴ is selected from the class consisting or hydrogen, C₁ to C₁₂ alkyl groups, C₁ to C₁₂ alkoxy groups, and phenyl groups, with the proviso that, when R³ and R⁵ are both ortho to the carbonyl group of Z, together they can be one of ##STR15## and R⁶, R⁷, and R⁸ are independently selected from the class consisting of hydroxyl, phenyl, C₁ to C₂ alkyl, C₁ to C₆ alkoxy, and --NR¹⁰ R¹¹ groups, wherein R¹⁰ and R¹¹ are independently hydrogen or a C₁ to C₆ alkyl group,

with the proviso that, when R⁹ is --CR⁶ R⁷ R⁸, one of the following must be true;

(1) at least one of R⁶, R⁷, and R⁸ is selected from the class consisting of hydroxyl, alkoxy, and --NR¹⁰ R¹¹ ;

(2) any two of R⁶, R⁷, and R⁸ together are one of --C_p H_2p -- and --OC_p H_2p O-- wherein p is either 2 or 3 so that they, together with the carbon atoms to which they are attached, form a 5- or 6-membered ring; and

(3) any two of R⁶, R⁷, and R⁸ together are a carbonyl group, provided that the remaining one of R⁶, R⁷, and R⁸ is selected from the class consisting of hydroxy, alkoxy, --NR¹⁰ R¹¹, and phenyl groups.

16. The process of claim 14 wherein said step of exposing said composition to energy forms a coatable syrup containing a solute polymer having a molecular weight of at least 500,000.

17. The process of claim 15 further comprising the step:

e) prior to irradiating said syrup, coating said syrup on a substrate.

18. The process of claim 17 wherein said substrate is a flexible web.