CA2298469A1 - Siloxane block copolymers for printable release coating - Google Patents

Siloxane block copolymers for printable release coating Download PDF

Info

Publication number
CA2298469A1
CA2298469A1 CA002298469A CA2298469A CA2298469A1 CA 2298469 A1 CA2298469 A1 CA 2298469A1 CA 002298469 A CA002298469 A CA 002298469A CA 2298469 A CA2298469 A CA 2298469A CA 2298469 A1 CA2298469 A1 CA 2298469A1
Authority
CA
Canada
Prior art keywords
release coating
block copolymer
siloxane block
printable release
present
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
Application number
CA002298469A
Other languages
French (fr)
Inventor
Xin Chen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Moore North America Inc
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of CA2298469A1 publication Critical patent/CA2298469A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D183/00Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
    • C09D183/10Block or graft copolymers containing polysiloxane sequences
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00Polymeric products of isocyanates or isothiocyanates
    • C08G18/06Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40High-molecular-weight compounds
    • C08G18/61Polysiloxanes

Abstract

A printable release coating comprising a siloxane block copolymer that is the reaction product of (a) a polydimethylsiloxane free of thio, mercapto, and fluorine groups and (b) an organic diisocyanate. Also, a method of making a siloxane block copolymer for use as a printable release coating, the method including reacting a polydimethylsiloxane with an organic diisocyanate and a chain extender.

Description

Title SILOXANE BLOCK COPOLYMERS FOR
PRINTABLE RELEASE COATING
Background Art Technical Field The present invention relates to printable release coatings. More particularly, the invention relates to a release coating including a siloxane block copolymer synthesized from an organic diisocyanate and certain polydimethylsiloxanes.
Description of Related Art Pressure-sensitive adhesives in the form of labels, for example, are typically coated with a release coating on the back side of the label, (i.e., on the side opposite the adhesive). This release coating is in large part responsible for making these adhesive materials removable without the need for excessive force and without causing delamination of the backing or offsetting of the adhesive.
To be useful as a release coating, a material generally should have low work of adhesion with the adhesive. Useful release coating materials also have suitable strength and possess good adhesion with the backing of the adhesive material. Finally, useful release coating materials prevent inadvertent transfer of the adhesive to the back (i.e., non-adhesive) surtace of the adhesive material. Release coatings make it possible, for example, for pressure-sensitive labels to be repositionable or removable.
Silicones are well known as release coatings for tacky materials,- e.g., as backing members for pressure-sensitive adhesives. Silicones are composed primarily of alternating silicon and oxygen atoms in the polymeric backbone. Any one of a number of organic groups can be attached to the silicon atoms to create polymers that are referred to as organopolysiloxanes.
The simplest polysiloxane, polydimethylsiloxane, is one in which methyl groups are attached to the silicon atom. The physical nature of polysiloxanes depends upon the degree of polymerization and upon the nature of the end groups in the polymer, which can range from chemically active to relatively inert.
One disadvantage of silicone coatings is that they tend to be expensive. In addition, the force to separate a pressure-sensitive adhesive from a surface treated with silicones is typically in the range of 10 to 40 grams per inch of width, a force much too low for the silicone to be effectively used as a low-adhesion backing. This poor adhesion may be due to the scarcity of polar groups in the organosiloxane polymer. The release characteristics of silicone, therefore, may present problems because the release properties are too good. For example, this can result in a roll of tape not remaining tightly wound, among other disadvantages. Also, the use of a primer layer between the silicone film and the substrate is often needed to help anchor the silicone film to the substrate.
As a result, attempts have been made to modify silicone polymers by blending or reacting them with other less effective release materials in order to obtain higher release force values. For example, it is known that siloxane block copolymers may be obtained by combining very specific polydimethylsiloxanes with organic diisocyanates. U.S. Patent No. 4,002,794 to Schwarcz discloses a release coating made of a copolymeric material that is the reaction product of a thio- or mercapto-terminated polyorganosiloxane and a diisocyanate difunctional organic compound.
Another example of a siloxane polymer or copolymer that has been used as a release material is fluorine-terminated polyorganosiloxane. U.S.
Patent No. 4,810,749 to Pinchuk discloses copolymers with a polymeric backbone having repeating isocyanate groups and repeating fluoroalkylsiloxane.
However, modified silicone polymers suffer certain disadvantages.
Some modified silicones contaminate a pressure-sensitive adhesive so that it loses its tackiness. Other modified silicones slowly react with a pressure-sensitive adhesive, causing inseparability upon aging. Some compositions are hard to reproduce consistently, e.g., the release properties change as the silicone gradually migrates to the surface. Other compositions require such *rB
high cure temperatures that the substrate on which they are coated may be melted or destroyed. Finally, some compositions are only effective when used in combination with a specific adhesive.
Certain substituents create more disadvantages and difficulties with the printable release coatings than others. For instance, the present inventor has discovered that a fluorinated polydimethylsiioxane would have a lower surface energy than a non-fluorinated polydimethylsiloxane and would thus be less printable. As a result, a lesser amount of a fluorinated polydimethysiloxane would be used in constructing the block copolymer. This would, in turn, result in a loss of flexibility in the final polymer, leading to a higher release force with a noisier release, known in the art as a more "chattery" peel. Further, it is advantageous to be able to print on such labels, e.g., with a thermal transfer printer, where the resulting print does not easily rub off or become smudged. Because of the aforementioned disadvantage, fluorinated polydimethylsiloxanes would not be suitable for such applications.
In contrast with the prior art, which required end groups on the polydimethylsiloxanes, e.g., fluorine, thio or mercapto groups, the present invention does not require such end groups on the polydimethylsiloxanes in order to obtain effective printable release coatings. The present invention thus avoids the accompanying disadvantages of such end groups. The inventor has found, in fact, that the composition of the present invention works better wifhout the above-mentioned end groups on the polydimethylsiloxane polymer.
The present inventor has found that a siloxane block copolymer-formed by the reaction of certain polydimethylsiloxanes with an organic diisocyanate is surprisingly successful as a release coating for pressure-sensitive labels.
Disclosure of the Invention To achieve these and other advantages, and in accordance with the purpose of the invention as embodied and broadly described herein, the present invention is directed to a printable release coating. The release coating includes a siloxane block copolymer that is the reaction product of (a) a polydimethylsiloxane free of thio, mercapto, and fluorine groups and (b) an organic diisocyanate.
The present invention further relates to a siloxane block copolymer for use as a printable release coating. The copolymer is the reaction product of (a) a polydimethylsiloxane free of thio, mercapto, and fluorine groups and (b) an organic diisocyanate.
The present invention also relates to a method of making a siloxane block copolymer for use as a printable release coating. The method includes the steps of (a) mixing a polydimethylsiloxane with a solvent; (b) mixing a diisocyanate with a solvent; (c) combining the mixture of (a) with the mixture of (b) at a temperature and for a time sufficient to allow the polydimethylsiloxane to react with the diisocyanate; (d) adding a chain extender to the reactants combined in step (c) and maintaining a sufficient temperature for a sufficient time to allow the chain extender to react.
Instead of blending materials having either good printability or good release properties, the inventor has synthesized siloxane block copolymers having both properties by reacting a polydimethylsiloxane with an organic diisocyanate. The siloxane segments of the block copolymer provide good release properties, while the polar (urethane and urea) segments provide printability.
The above and other advantages and features of this invention will become apparent upon review of the following detailed description.
Best Mode for Carrying Out the Invention The present invention relates to a printable release coating including a siloxane block copolymer that is the reaction product of (a) a polydimethylsiloxane free of thio, mercapto, and fluorine groups and (b) an organic diisocyanate.
The present invention further relates to a siloxane block copolymer for use as a printable release coating. The copolymer is the reaction product of (a) a polydimethylsiloxane free of thio, mercapto, and fluorine groups and (b) an organic diisocyanate.
Polydimethylsiloxanes useful in the present invention include, for example, amine-terminated oligomers and hydroxyl-terminated oligomers.
Examples of useful diisocyanates include, but are not limited to, isophorone diisocyanate, diphenylmethyl diisocyanate, toluene diisocyanate, dicyclohexylmethyl diisocyanate, and hexamethylene diisocyanate.
The materials used for synthesis of the siloxane block copolymer may also include chain extenders, catalysts, and solvents. A chain extender lengthens the distance between silicone segments in the siloxane block copolymer. In doing so, the chain extender imparts two properties to the block copolymer. First, the chain extender raises the surface energy of the block copolymer. This improves printability. Second, the chain extender imparts flexibility into the block copolymer. This reduces "chattery" (noisy) release as well as release force overall. "Chatter" is the zipping sound often made when tapes or labels are unwound from a roll.
The chain extender material used in the present invention may be selected from diols, triols, poly-ols, and their sulfur equivalents. Nitrogen analogues, e.g., diamines, triamines, polyamines, could also be used if a stoichiometric excess of diisocyanate is maintained. Preferably, the chain extender is polyethylene glycol, 1,4-butanediol or a mixture thereof. If the chain extender is polyethylene glycol, it is preferably present in the amount of about 0-50 parts by weight. If the chain extender is 1,4-butanediol, it is preferably present in the amount of about 0-20 parts by weight.
Catalysts useful in the present invention include, for example, ferric acetyl acetonate, tributyl tin diacetate, tin octoate, and dibutyl tin dilaurate.
Preferably, the catalyst used in the present invention is dibutyl tin dilaurate.
The catalyst serves to speed up the reaction and allow the reaction to take place at lower temperatures.
The solvents are used in the present invention to make it easier to mix the ingredients for reaction and aid in keeping the final product from solidifying, i.e., keeping its viscosity sufficiently low to make it pourable and coatable. Solvents useful in the present invention include tetrahydrofuran, xylene, and toluene. The preferred solvent is toluene. The solvent is *rB
preferably present in the amount of about 0-80 parts by weight, preferably in an amount of about 50-80 parts by weight.
The release coatings of the present invention may be used to make pressure-sensitive labels. The release composition may be slightly altered to provide the desired release properties and printability for different adhesives and printers. Pressure-sensitive adhesives, for example, could be either repositionable, removable, or permanent. Labels made with the release coatings of the present invention can be printed with a thermal transfer printer.
The present invention also relates to a method of making a siloxane block copolymer for use as a printable release coating. The method includes the steps of {a) mixing a polydimethylsiloxane with a solvent; (b) mixing a diisocyanate with a solvent; (c) combining the mixture of (a) with the mixture of (b) at a temperature and for a time sufficient to allow the polydimethylsiloxane to react with the diisocyanate; (d) adding a chain extender to the reactants combined in step (c) and maintaining a sufficient temperature for a sufficient time to allow the chain extender to react.
Preferably, the polydimethylsiloxane and the diisocyanate are reacted at a temperature of 60-80°C for 20-40 minutes. More preferably, the reaction time for the polydimethylsiloxane and the diisocyanate is 30 minutes. The chain extender is preferably reacted with the polydimethylsiloxane and the diisocyanate at a temperature of 60-80°C for 20-40 minutes, and more preferably for 30 minutes.
The present invention is illustrated by way of the following example. It is to be understood that the invention is not to be limited to the specific conditions or details set forth in this example except as such (imitations are specified in the appended claims.
Example 1 Polydimethylsiioxane (a,w-amine capped, 25.0 g Goldschmidt, MW = 11500) Polyethylene glycol (Dow Chemical, MW = 8000) 12.5 g lsophorone diisocyanate (Olin Chemical) 18.13 g 1,4-butanediol 6.66 g Dibutyltin dilaurate 0.2 g Toluene 180 ml 12.5 g of polyethylene glycol was dissolved in 50 ml toluene in a 500 ml flask at 60°C. Next the polydimethylsiloxane was mixed with 50 ml toluene and the mixture was added into the polyethylene glycol solution. 0.2 g dibutyl tin dilaurate, 18.13 g isophorone diisocyanate and 50 ml toluene were mixed.
This mixture was then added into the flask containing the polydimethylsiloxane solution. The temperature was maintained at 60 -80°C
for 30 minutes and the solutions allowed to react. Then 6.66 g of 1,4-butanediol was mixed with the remaining 30 ml of toluene and the solution was added to the flask. The temperature was maintained at 60 - 80°C for another 30 minutes.
The siloxane block copolymer formed in the flask was diluted into a 10%
solution with tetrahydrofuran and coated on thermal transfer paper {Consolidated Paper) with a #20 Meyer rod. The siloxane block copolymer release coating may be used with a pressure-sensitive adhesive, e.g., Swift 84425 hot-melt permanent, and is printable with a thermal transfer printer (Zebra 140) and a ribbon (Coding Products TTR 7981 ).
It will be apparent to those skilled in the art that various modifications and variations can be made in the composition and method of the invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided that they come within the scope of the appended claims and their equivalents.

Claims (16)

Claims
1. A printable release coating comprising a siloxane block copolymer that is the reaction product of (a) a polydimethylsiloxane free of thio, mercapto, and fluorine groups and (b) an organic diisocyanate.
2. The printable release coating of claim 1, further comprising at least one chain extender.
3. The printable release coating of claim 2, wherein the chain extender is polyethylene glycol present in an amount ranging from greater than 0 to about 50 parts by weight.
4. The printable release coating of claim 2, wherein the chain extender is 1,4-butanediol present in an amount ranging from greater than 0 to about 20 parts by weight.
5. The printable release coating of claim 1, further comprising a catalyst.
6. The printable release coating of claim 5, wherein the catalyst is dibutyl tin dilaurate.
7. The printable release coating of claim 1, further comprising a solvent present in an amount ranging from greater than 0 to about 80 parts by weight.
8. The printable release coating of claim 1, wherein the solvent is toluene.
9. A siloxane block copolymer for use as a printable release coating comprising the reaction product of (a) a polydimethylsiloxane free of thio, mercapto, and fluorine groups and (b) an organic diisocyanate.
10. The siloxane block copolymer of claim 9, further comprising at least one chain extender.
11. The siloxane block copolymer of claim 10, wherein the chain extender is polyethylene glycol present in an amount ranging from greater than 0 to about 50 parts by weight.
12. The siloxane block copolymer of claim 10, wherein the chain extender is 1,4-butanediol present in an amount ranging from greater than 0 to about 20 parts by weight.
13. The siloxane block copolymer of claim 9, further comprising a catalyst.
14. The siloxane block copolymer of claim 13, wherein the catalyst is dibutyl tin dilaurate.
15. The siloxane block copolymer of claim 9, further comprising a solvent present in an amount ranging from greater than 0 to about 80 parts by weight.
16. The siloxane block copolymer of claim 15, wherein the solvent is toluene.
CA002298469A 1997-09-05 1998-08-25 Siloxane block copolymers for printable release coating Abandoned CA2298469A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US92421297A 1997-09-05 1997-09-05
US08/924,212 1997-09-05
PCT/US1998/017424 WO1999013015A1 (en) 1997-09-05 1998-08-25 Siloxane block copolymers for printable release coating

Publications (1)

Publication Number Publication Date
CA2298469A1 true CA2298469A1 (en) 1999-03-18

Family

ID=25449892

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002298469A Abandoned CA2298469A1 (en) 1997-09-05 1998-08-25 Siloxane block copolymers for printable release coating

Country Status (7)

Country Link
EP (1) EP1015522A1 (en)
JP (1) JP2003523413A (en)
CN (1) CN1272126A (en)
AU (1) AU9114098A (en)
BR (1) BR9812158A (en)
CA (1) CA2298469A1 (en)
WO (1) WO1999013015A1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6432528B1 (en) 1998-12-09 2002-08-13 3M Innovative Properties Company Variably printed tape and system for printing and applying tape onto surfaces
KR101200293B1 (en) * 2003-12-22 2012-11-13 다우 코닝 코포레이션 Silicone compositions and their use in controlling the release or transfer of printed or molded patterns and transferring processes therefore
DE102006040846B4 (en) * 2005-08-31 2013-04-18 Mondi Gronau Gmbh Extruded film and its use
EP2892905B1 (en) * 2012-09-04 2019-01-16 Covestro Deutschland AG Isocyanatosilane with thiourethane structure
CN104086740B (en) * 2014-07-09 2016-05-04 温州柯莱恩科技有限公司 The preparation method of the organosilicon grafted and modified polyurethane resin of a kind of use for synthetic leather
WO2019148341A1 (en) * 2018-01-31 2019-08-08 Dow Global Technologies Llc Polysiloxane resin composition

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU591989B2 (en) * 1986-06-20 1989-12-21 Minnesota Mining And Manufacturing Company Block copolymer, method of making the same, diamine precursors of the same method, method of making such diamines and end products comprising the block
US5543171A (en) * 1992-12-14 1996-08-06 Shores; A. Andrew Process of manufacturing a coated article
US5496635A (en) * 1993-10-12 1996-03-05 Minnesota Mining And Manufacturing Company Directly printable coating for olefinic polymer films and articles utilizing such coating
CA2163611A1 (en) * 1994-12-15 1996-06-16 Wayne K. Larson Low surface energy sulfo-polyurethane or sulfo-polyurea compositions
AU5630296A (en) * 1995-04-25 1996-11-18 Minnesota Mining And Manufacturing Company Polydiorganosiloxane polyurea segmented copolymers and a pro cess for making same

Also Published As

Publication number Publication date
WO1999013015A1 (en) 1999-03-18
BR9812158A (en) 2000-07-18
AU9114098A (en) 1999-03-29
JP2003523413A (en) 2003-08-05
CN1272126A (en) 2000-11-01
EP1015522A1 (en) 2000-07-05

Similar Documents

Publication Publication Date Title
JP4180789B2 (en) Silicone copolymer modified release tape
JP3780324B2 (en) Diblock polydiorganosiloxane-polyurea block copolymer and triblock polydiorganosiloxane-polyurea block copolymer
US3957724A (en) Stratum having release properties and method of making
JP2784761B2 (en) Organopolysiloxane-polyurea block copolymer and method for producing the same
US4002794A (en) Adhesive material and articles incorporating same
JP3198926B2 (en) Curable silicone release agent composition and release paper
JPH11504372A (en) Polydiorganosiloxane polyurea segment copolymer and method for producing the same
EP0742803A1 (en) Water-based polyurethane polymer, release coating, adhesive tape and process of preparation
EP0606532A1 (en) Silicone polyelectrolyte aqueous coating solution
EP1873177A1 (en) Isocyanate-terminated urethane prepolymer, process for producing the same, and adhesive comprising the urethane prepolymer
US5543171A (en) Process of manufacturing a coated article
CA2298469A1 (en) Siloxane block copolymers for printable release coating
JP4367670B2 (en) Silicone composition for forming a peelable cured film
US4521471A (en) Processes and articles for removing typewriter inks
JP2797902B2 (en) Silicone composition for release agent
MXPA00002228A (en) Siloxane block copolymers for printable release coating
JPH01215857A (en) Organopolysiloxane composition for release paper
JP2003105089A (en) Organohydrogenpolysiloxane mixture and repellent cured-film forming silicone composition
US5959034A (en) Curable silicone composition
JPH04272959A (en) Releasing silicone composition
JP2004017288A (en) Curable silicone release agent composition and release paper using the same
JP2746811B2 (en) Method of forming release silicone cured film
JP3553111B2 (en) Silicone composition for release paper
JPH0797520A (en) Organopolysiloxane composition
US4519720A (en) Process and articles for removing typewriter inks

Legal Events

Date Code Title Description
EEER Examination request
FZDE Discontinued