CA1091844A - Bonding method - Google Patents

Abstract

A method is disclosed for forming a strong bond between a substrate and a solid thermoplastic polymer which comprises melting a thermoplastic polymer having an effective open time (a period after melting the polymer during which it remains aggressively tacky and bondable below the melting temperature),cooling it below the melting temperature, contacting the open polymer with a substrate and allowing the polymer to revert to its non-bondable, solid state. Also disclosed are a class of polyesters suitable for use in the method and certain novel articles adapted for carrying out the method.

Description

109184~

BONDING METHOD

m is invention concerns a method for forming a strong, dependable adhesive bond without sub~ecting the substrate bonded to high temperature and without lnvolving volatiles~ a class of segmented copolyesters by which the method of the invention can be practiced and certain novel articles adapted for carrying out the method.
m e method comprises , .
- (1) melting a solid, relatively strong thermoplastic ~
polymer (which is free of solvating agents, ~`
including solvents and plasticizers) having an f/ open time of at least about l/4 minute at 20 C., .,

(2) cooling the polymer below its melting temperature,

(3) bringing the polymer into contact with a sub-strate at a temperature below the polymer i~ 15 melting temperature and while the polymer is th~ still open, and

(4) maintaining the polymer and the substrate in contact until the polymer has reverted to its solid, non-bondable state.
Surfaces can be bonded together by this process or strong, adherent coatings can be applied to substrates.
The segmented copolyesters of the invention are solld, non-tacky, strongly cohesive, solvent-free thermo-plastic polymers which are themselves not sub~ect to cold ; 5 flow and are non-blocking below their melting temperatures .; but which become aggressively tacky and bondable upon Y being melted~ m ey consist essentially of from about ' 5 to 75 percent ~y weight of amorphous ester units and 95 4~

to 25 percent by weight of crystallizable ester units joined through the ester linlcages ~"crystallizable" as used herein includes both crystalline ester units and units which are capable of becoming crystalline).
The crystallizable units are of the formula:
O O
ll ll ' -CRlC-R2-and the amorphous ester units are of the formula:

O O
.

wherein Rl consists of divalent radicals remaining after removal of the car-boxyl groups from one or more saturated aliphatic dicarboxylic acids and/or aromatic dicarboxylic acids, Rl containing from 2 to 8 carbon atoms when it is ;~ an aliphatic radical and being phenylene when it is an aromatic radical, R2 consists o divalent radicals remaining after removal of the hydroxyl groups rom one or more saturated aliphatic diols containing from 2 to 12 carbon atom5, R3 is Rl or R5, R4 is R2 or R6, R5 consists of the divalent radicals containing from about 22 to 50 carbon atoms which remain after remoYal of the carboxyl groups from saturated aliphatic dimer acids and R6 consists of the divalent radicals remaining after removal of the hydroxyl groups of long chain aliphatic diols having an average molecular weight of 200 to 4000, provided that at least one of R3 and R4 in each amorphous ester unit is R5 or R6, and provided also that when Rl is aromatic, R2 contains from 6 to 12 carbon atoms ~~< and the amorphous content is 50-75 percent by weight, the said copolymer havlng a DTA melting temperature from about 25 to 150C., and an inherent vis-cosity of at least 0.5 dl/g at 25C., as measured in 0.3 g/dl solutions of polymer in chloroform at 25C., an open time of at least about 1/4 minute at ; 20C , substantially complete solubility in toluene at 25C, in the ratio of :
about 10 percent by weigh~. of copolyester and 90 percent by weight of solvent, a tensile strength of lOG-400 kg/cm, an elongation at break of 400-1000 percent, a T-peel adhesion to vinyl of at least 0.9 kg/cm of width and a DTA glass . transition temperature, Tg, below -25C.
The copolyesters become bondable initially only when heated to or ~ `, `,) 109184~1 above the melt temperature, but have the remarkable property of remaining "open", i.e. bondable and tacky for a period of time ranging from a few seconds to many minutes after they have been cooled below the melting temperature and to ordinary (room) temperature, i.e. 20-25C. or even lower (the open time of any particular polymer depending largely upon its chemical composition). While ;
the polymers are open they adhere strongly to substrates which are themselves at ordinary temperature (often far below the polymer melt temperature). The open times of the copolyesters are at least about 1/4 minute and 20C. and or-dinarily they are not more than about 1 hour at 20C.
At the end of the open time a thermoplastic bond forms, i.e. which is firmly set and of relatively high strength but capable of being broken by heating.
Preferably the copolyesters have melting points of at least 40C., although in certain applications (e.g. where they are used in die replication as temperary binders in the preparation of fugitive molds) polymers melting down to 25C. are useful. Por most adhesive, tape, permanent binder and coating applications, the polyors should have melting temperatures of from about 65 to 150 C
and such copolyesters form a particularly pre~erred clas~.
The open tlme depends upon the composition of the particular copolymer Small amounts of other materials which do not interfere with the polymerization reaction to form the segmented copolyester can be present. To enhance the open time and/or solubility of the copolyesters in which R
is entirely aromatic, they pre~erably contain at least 50 percent by weight o~ amorphouæ ester unitæ. In any event, , R2, ~ , R4 and any other building block æhould be selected such that the segmented copolyester has a differen-tial thermal analysis (DTA) melting temperature of from ,., about 25 to 150 C. (pre~erably 65 to 150 C,), an inherent viscosity Or at least 0.5 dl/g and an open time of at least about 1/~ minute at 20 C.
!' me open time measurements herein are made by heating on a hot plate a 2.5 cm x 7.5 cm x 300 micron strip o~ the polymer to its melting point on a 2 mm glas~
plate (microscope slide), removing the glass plate from the hot plate and immediately placing it polymer side up on a heat insulating sur~ace, such as a thick paper pad, r,~ at about 20 C. me open time is the elapsed time ~rom placing the hot slide on the heat insulating sur~ace until a paper strip placed in contact with the copolyester surface will no longer bond. m e melting temperatures are - determined by differential thermal analysis (DTA) and are taken at the peak of the maximum endotherm. m ey are mea-sured in an atmosphere of helium at 740 mm. of mercury pressure at a temperature rise of 30 C./minute, the test ' 1~91~44 ordlnarily being run over the range of from about -140 to +200 C. m e detalls of this method are described, for ; example, by C. B. Murphy ~n "Dif~erentlal m ermal Analysis", R. C. Mackenzie, Editor, Volume I, pages 643 to 671, : 5 Academic Press, New York, 1970.
The copolyesters of the invention are substan-tially linear, of relatively high molecular weight and strength and they adhere well to a variety of substrates, including porous materials (such as wood, paper, etc.), glass and ceramics, metals (such as anodized aluminum), other polymers (such as polyesters, polycarbonates, vinyls and polystyrene), etc.
m e copolyesters o~ the lnvention are normally - also characterized by:
(1) tensile strengths o~ 100-~00 kg/cm (2) elongations at break, of 400-1000 percent (3) T-peel adhesions to vinyl of at least 0.9 . kg/cm of width (4) DTA glass transition temperatures, Tg, below . 20 -25 C.
. (5) substantially complete solubility in toluene at 25 C. in the ratio of about 10 percent by .~ weight of copolyester and 90~ by weight of . ~ solvent.
`. 25 Normally also they have acid values of 5 or less.
.~
The end groups o~ the polymers can be either carboxyls or hydroxyls (or simple derivatives thereof su~h as esters9 acid chlorides and anhydrides).
me tensile and elongation at break are measured by ASTM test method D 882, and the T-peel ad~esion by ASTM

. --5--:

9184~

test method D 1876-69 at a separation rate of about 30 cm/minute (the tensile, elongation and T-peel being run at room temperature: 20-25 C.). The glass transition temperature (the temperature range at which an amorphous polymer changes from a brittle glassy state to a flexible rubbery state) is measured by differential thermal analysis by the procedure described previously relative -; to the melt temperature determination. m e acid number iæ
, . .
the number of milligrams of potassium hydroxide per gram of polymer required when titrating to bromothymal blue endpoint.
Normally and preferably the copolyesters contain only carbon, hydrogen and oxygen.
- m e diacid precursors containing Rl are often referrsd to herein as short chain diacids, the diol pre-cursors containing R2 as short chaln diols, the diacid precursors containing R5 as long chain diacids and the diol presursors containing R6 as long chain diols.
m e relative amount of crystallizable and amorphous units is determined by the precursor charge.
Moæt frequently the copolyesters are reaction products of a long and a short chain precur~or of one functionality and a short chain precursor of the other functionality.
In case of such ia stoichiometrically balanced charge of three monomers, the weight percentages of amorphous and crystallizable units can be calculated exactly (this is also true where there are more than three monomers but of only three types, e.g. two short chain diacids, one short chain diol and one long chain diol but no long chain diol, etc.). However, if monomers of all four type~ are ,:.

10~9184~

included in the charge, the relative amounts of amorphous and crystallizable units are not exact but can be expressed as falling between two values (the range being quite narrow).
Thus, to calculate the minimum amorphou~ content in such a copolyester, it is assumed that the maximum possible reaction occurs between the short chain diol and short chain diacid (thus maximizing the content of crystallizable units). To calculate the maximum amorphous content, it is assumed that the maximum possible reaction occurs first between the - 10 short chain diacid and the long chain diol and the short chain diol and the long chain diacid, the remaining ~ reactants after those reactions (if any remain) reacting - with one another.
The amorphous and crystallizable units of the copolye~ter~ can alternate in the polymer chains or they $ can appear in blocks of the same type and thus can be controlled to some extent by the process of preparation.
..
For example, prepolymers of crystallizable and/or amor-phous units can be prepared separately thus assuring larger blocks of one type or the other or, a~ is the usual practice, the precursors (monomers) can be charged directly and simultaneously to the reaction vessel. It has been found, however, that these variations cause only very minor, if any, differences in the final polymers and that the produc~s of the polymers are largely determined by the proportions and chemical natures of the individual ;; crystallizable and amorphous units as defined previously and by the molecular weight of the linear polymer.
The amorphous blocks of the copolyesters of the ~; 30 invention are most often composed of alternating long 10~91844 chain diol and short chain dlacld residue~, but this is not necessarily the case.
m e preferred short chain diols are 1,5-pentane-diol and cyclohexane-1,4-dimethanol whlch may be a mixture of cis-trans isomers such as a mixture containing about 30% cis- and 70% trans- cyclohexane-1,4-dimethanol.
me chemical structure of the long chain diol is not critical. Any substituent groups which do not inter-fere with the polymerization reaction to form the copoly-ester can be present. Thus, the chain can be a single divalent acyclic or alicyclic, hydrocarbon group, poly-(alkylene oxide) group, polyester group, a combination thereof, or the like. The hydroxy functional groups cf the long chain diols should be terminal groups to the extent po~ible.
The long chain diacid~ include dimerized and hydrogenated ethylenically unsaturated C12-C26 fatty acids (such as are described in U.S. Patent 3,538~oog).
m e copolyesters can be prepared by conventional polycondensation polyester-forming reaction~ preferably with a cataly~t. The reactions are generally carried out in the melt, however, a solvent may be utilized for azeotropic removal of the condensation by-product.
m e choice of catalyst depends on the starting materials. The short chain diacid alone may serve in some caseæ, although it i5 preferred to use a compound having an ionization constant greater than about 10-3, e.g.
p-t-butylbenzenesulfonlc acid. For esterification by ester interchange, an ester interchange catalyst is used. m e~e include manganous acetate, calcium acetate, zinc acetate~

sodium methoxlde, antimony oxlde, antlmony glycoxide, tetraalkyltitanates, complex tltanates such as magnesium hexaalkyltitanates, etc.
An ester interchange can include heating the dimethyl ester of a short chain diacid with a short chain dlol and a long chain diol in the presence of a suitable catalyst at 150 C. to 180 C. A~ter about three hours~
75 to 90 percent of the theoretical amount of methanol will ordinarily be distilled off and the copolyester prepolymer will have an inherent viscosity of less than 0.5 dl/g and an acid vaIue of more than about lO. m e pressure of the reaction vessel is then reduced to about 5 mm (Hg.) and heating is continued for l to 2 hours at about 200 C.
Finially, the pressure is reduced to less than l mm and heating l~ continued for 3 to 5 hours at about 210 C. The copolymerization reaction is complete when the inherent viscosity of the cop~lyester is about 0.5 or greater, usually about l and the acid value is about 5 or less. It is preferable to carry out the conversion o~ the prepoly-,.", .
mer to the product copolye~ter in the presence of an anti-i ox~dant such as sym-di-~-naphthyl-p-phenylenediamine or ~-j 1,3,5-trimethyl,2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)-benzene or a hindered polyphenol such as "Irganox lOlO"
r` ~reJer~ s and "1076" (~rod~ot~ o~ Ciba Geigy).
25 ~ Furthe~r advancement, e.g. chain exten3ion, can be obtained using difunctional isocyanates, dihalosilanes such as diphenyldichlorosilane, by reacting with epoxy-silane such as ~ 3,4-epoxycyclohexyl)ethyltriethoxy ,~ .
` sllane, etc.
-_g _ ",~
..
.,~
.~

-- iO~i~4~

Among the areas in which the copolyesters are advantageously used as bonding agents are protective coatings, surface primers (e.g. on polyesters, such as polyethylene terephthalate), heat activated adhesives (used per se as well as in heat activated transfer tapes and fiber-reinforced adhesive films), as permanent binders (e.g. in various sheet products such as magnetic tapes) as temporary binders, etc.
A particular area of utility for certain of the copolyesters of the invention is as binders in magnetic recording media which comprise a non-magnetizable backing member bearing a coating of magnetizable particles in a -; 10 binder. The binders in these articles comprise copolyesters of the present invention consisting essentially of about 25 to 75 percent by weight of amorphous ester units and 75 to 25 percent by weight of crystallizable ester units in which ~ is primarily tetramethylene, and/or phenylene, the copoly-esters having DTA melting temperatures of from about 65 to 150 C. and DTA
glass transition temperatures, Tg, below 0 C.
The copolyesters can be used in thermally activatable pressure sensitive tape constructions in combination with a wide variety of sheet ' backings including films such as polyesters including polyethylene terphthal-~: ate, cellulose acetate, ethyl cellulose, polyvinyl chloride, vinyl acetate-vinyl chloride copolymers; polyolefines such as polyethylene; polyurethanes;
fibrous backings such as paper ~nd cloth, metal foils, such as aluminum foil, foams such as urethane, polyvinyl chloride and polyolefin foams, etc.

.

,; --10--: ~.

10!~18A4 The copolyesters can be thermally pressed into films, hot melt or extruder coated onto flexible or inflex-ible substrates, coated from solution, or formed into various shapes by extrusion, molding, casting, etc. Films of the copolyesters can be further processed by cold drawing and heat setting. Normally they are either solvent coated or extruded onto appropriate liners or backings for the manufacture of tapes. When used as adhesives per se, they can be hot melt coated onto substrates for bonding at the time of use. The need for low adhesion backsizes or low adhesion liners in any of the tape products of the invention (to allow the tape to be more readily unwound ~ from the roll form) depends to a large extent on the ; speci~ic copolyester u~ed.
An adhesive transfer tape, comprising a temporary low adhesion laminate backlng, and a film of a copolyester o~ the inven~ion may be stored in roll form. At the time of use, it is heated above the melt temperature of the copolyester. Then, while the copolyester is still open it is applied to a surface and the temporary backing is remove~
exposing a second tacky surface of the copolyester layer, to which another surface is adhered. At the end of the open time of the copolyester the two surfaces are strongly bonded. In another type of product, a non-woven fibrous web is included as an internal network within copolyester layer, cons~derably enhancing its film strength. Likewise unlinered transfer tapes are contemplated in which a film - of the copolyester is itseif wound in roll form (without the temporary laminate backing). In such an article care must be taken not to heat the tape roll above the melt temperature of the polymer in order to avoid fusing the convolutions to one another.
Assuming that a reasonably high molecular weight is attained (as indicated by an inherent viscosity of at least about 0.5 dl/gm), the physical properties of the copolyesters, such as the melt temperature, the glass transition temperature, the tensile and elongation, adheæive properties, and the open time, can in general be controlled by ad~ustment o~ the amounts and nature oi the constituents. Thus~ in general, as the weight percent of amorphous units is increased in the copolyesters, the open time is lengthened and the melt temperature is lowered.
Also, in general, the copolye~ters of the longer chain aliphàtic dlcarboxylic acids (~uch as azelaic acid and sebacic acid) tend to have lower melting temperatures than i those of the shorter chain dicarboxylic acids (such as ~ adipic acid) Since the combination of properties desired -will vary wldely with the pro~ected end use, a variéty of - chemical makeups are preferred for dlfferent products.
. .~
. 20 The copolyesters can be modified by the incorpor-..
ation of ~illers, pigments, dyes and other modifiers where opacity, color~ increased firmness or other effects are desired~
.~
In the following examples, all parts, proportions and percentages are by weight unless otherwise indicated.
- m e procedures for most of the tests reported in the examples have been described previously. Unless . .
; otherwise specified, conditions for the T~peel tests were as follows: Strips of anodized aluminum (1.25 cm x 15 cm x 0.002 cm) were bonded to blocks o~ smooth polyvinyl .

` .

lO~9i844 chloride resin (5 cm x 13 cm x 0.4 cm) with a 0.00125 cm coating (approximately) of the copolyester being tested.
m e polymers of the invention generally elongate at con-stant tenslle until they reach a yleld point at about 200 percent elongation after which the tensile increases (indicating crystallinity and orientation). m e T-peels and tensiles were run at room temperature at a ~aw separa-tion rate of about 30 cm per minute. All of the polymers of Examples 1-40 were substantially completely soluble in toluene at 25 C. in the ratio of about 10 percent by weight of copolyester to 90 percent by weight of solvent.
The following abbreviations are used in the examples. Subscript numbers following abbreviations for the glycols indicate the approxlmate molecular weight of the material indicated.
AA adipic acid SA sebacic acid DA dimer acid (hydrogenated dilinoleic acid) CHD 1,4-cyclohexanedimethanol PTMEG poly(oxytetramethylene)glycol PCLD polycaprolactonediol PEG poly(oxyethylene)glycol PBD polybutadiene PECG polyoxyethylenecarbonate glycol Example 1 A copolyester of the invention having 52.0 crystallizable blocks and 48.o% amorphous blocks.
A 3-neck flask is fitted with a mechanical stirrer, a Dean-Starke trap-condenser, a thermometer, and a gas inlet for maintaining an inert atmosphere within the flask. The following are charged to the ~lask:
30.7 parts Adipic acid 27.2 parts 1,4-Cyclohexanedimethanol 42.1 parts Poly(oxytetramethylene)glycol (2000 molecular weight) 0.021 parts Antimony glycoxlde Inert gas i8 introduced into the ~lask and the contents of the flask brought to 170 C. by means of a heated oil bath. The mixture is stirred and held at this temperature for about three hours. During this time, water resulting from the condensation iB collected in the trap.
m e temperature of the mixture is reduced to about 145 C., and the pressure is then reduced to 5 to 0.25 mm Hg. These conditions are maintained for about one hour to remove additional volatile materlal. About 1 part o~ sym-di-B-naphthyl-p-phenylenediamine (an antioxidant) is then added while maintaining an inert atmosphere. m e temperature of the mlxture is increased to 200 to 220 C. and the pressure reduced to 0.15 mm Hg and these conditions maintained for approximately 4 hours.
The polymer solidifies to a tough, flexible, colorless, opaque material having an inherent viscosity of , o.8 dl/g, a melt temperature (Tm) of about 90 C., a glas~
transition temperature (Tg) of -82 C. and an acid number (or value) of 2Ø It has an open time o~ ~ minutes, a room temperature tensile strength of 135 kg/cm2 and an elongat10n at break of 650%. The T-peel (vinyl) of this 9,', polymer is 2.9 kg/cm of width (16 pounds per inch). Strips C f anodized aluminum on polystyrene and Lexan~bonded by the :., polymer have T-peel strengths of 1.6 and 2.1 kg/cm (9 and ade~ark ;' 1091~344 12 pounds per inch) respectively. A polyester prepared in a similar manner using only adipic acid and 1,4-cyclo-hexanedimethanol has an open time of less than one minute and does not wet vinyl, polystyrene, or Lexan resins sufficiently to provide a bond.
Example 2 A copolyester of the invention having 43.7-47.0%
crystallizable blocks and 53.o-56.3% amorphous blocks is prepared in substantially the same way from 24.9 parts of adipic acid, 24.3 parts of hydrogenated dilinoleic acid, 29.4 parts of 1,4-cyclohexanedimethanol, 21.4 parts of poly(oxytetramethylene)glycol (2000 molecular weight), 0.1 part of Irganox (ankioxidant), and 0.1 part of tetra-butyltitanate (catalyst).
The polymer solidifieæ to a tough, flexible, colorless, opa~ue material having an inherent viscoslty of - o.85 dl/g, a Tm Of about 79 C., a Tg of -72 C. and an acid number of 5. It has an open time of 6 mlnutes, a room temperature tensile strength of 105 kg/cm2 and an elonga-tion at break of 600~. Its T-peel strength is 4.3 kg/cm of width.
':;
m e copolyesters of the remainder of the examples are prepared utilizing essentially the same process, except .
as otherwise specifically indicated.
Exam~les 3-7 .., Copolyesters of adipic acid, 1,4-cyclohexane-dimethanol and poly(oxytetramethylene) glycol molecular , ,.
weight about 2000 varying in amorphouæ content from about 30 to 70% and control. Th~ compositions are:
~..

, .
, i, .

1091~344 Short Chaln Diol/
Example Wt % Long Chain Diol ~:
No. AmorPhous Mole Ratio 3 o 100/0 4 30.3 95/05 40.0 92.5/7.5 6 48.o go/lo 7 67.6 80h0 Examples 8-12 Copolyesters of adipic acid, 1,4-cyclohexane-dimethanol and various polyglycols havlng molecular weights - ~
of approximately 1000, the copolyesters varying in amor- ~.
phous content from about 25j¢ to about 65% and control. I~e - compositions are:
Short Chain Diol/
: Example Polymeric Wt % Long Chain Diol No. Gl~colAmorphousMole Ratio ; 3 _- O 100/0 8 750 27.3 9o/lO
9 P~MEGggo32 . 5 9o/lO
0 PBDlOOO(l)32.6 9o/lO
11 PT~ggo 52.2 80/20 12 P~!EGggo 65.1 70/30 (l)A hydroxy-terminated polybutadiene ` 25 having a molecular weight of about - 1000 available under the trade designation "Hystl G-1000" from the Hystl Development Co.
Examples 13-18 .... .
Copolyesters of sebacic acid, cyclohexanedimethanol and long chain diols varying in amorphous content from abqut 10 to 30% and control. me compositions are:

: 1 ~ --16--:.
.~, .. , . . . .. - ` ~
... . . . . . .

10~1844 Short Chain Diol/
Example Polymeric Wt % Long Chain Diol No._ Glycol Amor~hous Mole Rat_o 13 __ 0 100/0 14 PTMEG630 11.9 95/05 PEG1000 16.4 95/05 16 PTMEGggo 16 . 3 95/05 17 PCLD1250 19.3 95/05 18 99O 29. 3 go/lo Examples 19-21 Copolyesters of adipic acid, cyclohexanedimethanol and hydrogenated dilinoleic acid whlch vary in amoxphous content ~rom about 20 to 65 percent and control. m e compositions are:
Example Wt % AA/DA
No. Amorphous Mole Ratio 39.9 80/20 21 64.o 60/40 Examples 22-25 Copolyesteræ of adipic acid, 1,4-cyclohexane-dimethanol, poly(oxytetramethylene)glycol having a molecular weight of about 2000 and hydrogenated dilinoleic acid which vary ln amorphous content from about 30 to 65 percent. The composltlons are:
`~. Short Chain Diol/ AA/DA
Example Wt ~ Long Chain Diol Mole No. AmorphousMole Ratio Ratio .
22 34.3-38.o 95/05 95/05 ;~ 23 41.0-44.5 95/05 90/10 24 53.0-56.3(1)95/5 80/20 61.8-64.~ 95/05 70/30 (l) me same as Example 2 ~091844 ExamPles 26-30 Copolyesters of azelaic acid, 1,5-pentaned~ol and poly(oxytetramethylene)glycol having a molecular weight of about 630, the copolyesters varying in amorphous content from about lO to 45 percent and control. m e compositions are:
Short Chain Diol/
Example Wt % Long Chain Diol No. AmorPhous Mole Ratio 27 13.8 95/05 ~-28 35.0 85/15 -29 39.3 82.5/17.5 43.4 80/20 Example3 31-32 Two copolyesters having amorphous contents ln the range o~ 30-34 percent. The composition~ are:
Example No. 31 32 ;: ; Charge (parts by weight) Adipic Acid 32.4 34.5 ,: .
Sebacic Acid 7.8 5.3 Cyclohexanedimethanol 33.9 34.2 Poly(oxytetramethylene) - glycol, m.w. 990 25.9 26.0 ~; 25 Irganox lOlO (anti- -~; oxidant) 0.1 0.1 AA/SA mole ratio 85/15 90/10 Cyclohexanedimethanol/-Poly(oxytetramethylene) ~ 30 glycol mole ratio 90/10 90/10 -~ Weight Percent Amorphous 3105 31.8 c The mole ratios of adipic acid to sebacic acld range ~rom about 80/20 to 95/05 and the mole ratios of .. .
r --18-->,.
., .

~ .
.~, lO~i84~

1,4-cyclohexanedimethanol to poly(oxytetramethylene) glycol range from about 85/15 to 95/5.
Examples 33-38 Copolyesters of dimethylterephthalate, various linear (unbranched) aliphatic diols containing ~rom 6iX to twelve carbon atoms and poly(oxytetramethylene)glycol having a molecular weight of about 2000, the copolyesters varying in amorphous content from about 50 to 75~ by weight. m e compositions are:
Short Chain Diol/
Example Aliphatic Wt % Long Chain Diol No. Diol Amorphous Mole Ratio 331,6-hexane 60 85/15 diol ~
34 Same 68 80/20 Same 74 75/25 361,8-octane 58 85/15 diol 37l,10-decane 55 85/15 diol . 381,12-dodecane 53 85/15 diol ExamPles 39-40 Copolyesters o~ dimethylsebacate, dimethyltere-phthalate, 1,4-cyclohexane dimethanol and polytoxytetra-; methylene) glycol having a molecular weight of about 990 containing about 16 to 17 percent of amorphous units. The compositions are:
Dimethyl-sebacate/
Dimethyl- Short Chain Diol/
Example terephthalate Long Chain Diol Wt %
No.Mole Ratio Mole Ratio Amor~hous 39 95/5 95/5 16.3 4097.5/2.5 95/5 16.5 '.' '' -19-';.

,......................................................... .

iO9it~4 me characteristics of the copolye~ters of Examples 3-40 are given ln the I ollowing table:

~ ';
;' :
,:
~'' . .
.,~ :
,," .
~; ; .
'.
,.
.:
,........................................................................... .
., .
~ .

`: ~
.~
.'5 , :.;~, ,.i .~
.'~,:' :.., .,X

. ., . ' , .
:' .. ''i .

'a :s o ~ ~J o 3 a~ O a:~ o o o L~ o O
CC ~ L~ O t~ N ~ 1 ~) O ~ 1 ~1 0 0 0 U~ U~
V

C ~
~ 1 3 L~ O ~ O Lr~ o ~1 1~ o Lr~ O O O O IS~ ~I O O O
~1 0 O OC~ O O~ t-- CO OC) O ~> O O OD ~1 ~ I~ O ~
C~
~;la ~oooo~1oooo,~o~,1o,~ooo,~o ~1 0~
Q.~ O o ~ t~ J o ~1 ~rl 3 ~ o o o o o ~1 ~_ ' U~ O O O O U~ O O O U~ O U~ O O
~E-I E3 o ~I ~ J ~ 1 3 L~ ~ 3 . , .

" ~ OOOOOOOOOOOOOOOOOOOOO
a~ o o o 1~ o o o o o o o o o 11~ o 11~ o o o It~
~ m~ O O O O O
: _ ~ U~ 30 ~0 0 ,, a~
, ',;
_ O o o It~ 3 Lt~ O 0 3 00 3 ~1 3 Ir~ O O 0 3 ~1 ~, ,1 ~ ,~ ~ ~ ~ ~ ~ ~ ~ In ~ c~ ~ ~o ~ 2~ o o o u~
~ t~ 1 t~ 1 ~1 ~1 ~1 ~1 ~ ~1 ~1 ~1 ~1 ~I N N N ~`J ~1 : _ ," 'V .
, ~o n ~--U~ tO O~ I J J O ~O 00 C~J 11~ t-- IS'~ 3 J O ~ D 3 ., :-, . ~, O t~l O O ~ ~ ~ J O 00 0 0~ 3 1~ 00 1~ 0 ~ Lt~
00 o CJ~ J J J ~ 3 0~

.,'"~ ,_1 .' O tY') J IS~ O ~ ~ O ~1 ;.` ,~1 :~ ~

o lS~ O

: .
' . .
- ~ . . ":, ~, . .

iO91844 ,, ~ ~.
1 1~ ~J 3 ~ U~ ~ ~
Cl ~

ooooooo~o1~ooorloo ~C0 oOOOOOOOOoOOOoOO;O

0 C~ ~S N O O O O O O O O J :S ~I r--i ~i 0 0 i /~11 All All All All Ali All E~ ~ !C ~ ' ~ .11111 1 ~ 1~ C~ O O U~ O O O O O 11~ N N N N
,O E~ ~ ~D O ~O O ~ O U~ ~ ~ O O O O O O ~1 ~

OOOOOOOOOOOOOOOOO
, ~d ooooooo1~ooooooooo . bO ~ ~ ~ O O O O C ~D ~O O O O O O O O O
~ m ~ I o O O O o O O O O l O O O
~ ~ O O O O O O O O O O O O O
~ ~r ~r ~ J :t J J ~ J ~ J ~t :~

.' ~, ~oooooooooooooooo ',le O O O O O O O ~ ~ 0 O 0 0 o O 0 O ~
,.1~ ~ rl ~1 ~ J ~ 5 S ~ r^1 ~ s~ ~f ~r 1~ 3 3 J

"' ~ OOOOO OOOOOOOO
r.;~ :
`;t ,.,j0 ~q 0 ~ N 00 0 0 N Ir~ N J ~ N ~ J ~ J 3 e I ~
''s ..;
3 oo ~ o J o o o o o~ ~D
, ~ ~ ,, e ~ ~ ~D J ~ n ,1 o ~ ~
~ ~ --I ~1 ~1 ,1 ,1 ~ 7 o J ~ o ,~ N ~ ~ ~ O
X ~ ~J N N ~J N ~1~ ~ ~r) ~ ~) ~) ~ l~ tr) l ~) ~
.,.,,, ~13 ~ O U~ O

.~ -2~ -.~j :~ `
;,.`~
. .,, ~ .
.,.;; .

''"I ' lO9i844 The copolyester of the type of Examples 3-7 which contain from about 30-33 percent, 46-50 percent and 66-70 percent amorphous content form preferred classes as hot melt adhesives, primers (especially for use on polyethylene tere-phthalate films) and binders for certain sheet products respectively. The ad-hesion of the copolyester of Example 10 to terpolymers of acrylonitrile-buta-diene-styrene terpolymers (specifically ABS-Royalite 20, trademark of United States Rubber Company) is particularly high. The copolyesters of the type of Examples 22-25 which contain from about 40 to 65 percent amorphous ester units form a preferred class. The copolyester of Example 24 (which contains about 53-57 percent amorphous units and for which the ratio of glycol to di-acid content is about 3:7) is particularly preferred as an adhesive in heat activated transfer tapes due to its combination of relatively long open time and high adhesion. The copolyester of Example 34 is particularly preferred as an adhesive in heat activated transfer tapes due to its combination of open time, T-peel, adhesion and high temperature shear adhesion.
Example 41-42 Advancement of a copolyester of sebacic acid, 1,4-cyclohexanedimethan-ol and poly(oxytetramethylene)glycol, having a molecular weight of approxi-mately 630. The copolyester contains about 11 weight percent amorphous units .~ 20 and the short chain diol to long chain diol mole ratio is 95/05 (the same '~'1 constituents as Example 14). It is prepared in the usual way and is then re-acted with one percent by weight of an epoxy silane ( ~3,4(epoxycyclohexyl) , ethyltrimethoxy-, . . .
", ~ ~ .
,r.
.~ .
.~:
.... .
'' ''~

~'' .,.' ~ G -23-'~

10~84~

silane ("A186", Union Carbide and Carbon Corporation)).
The epoxy sllane (1 gm) is added dropwise over about 15 minutes to 100 g of the original copolyester in a nitrogen atmosphere at 180 C. with stlrring and the mixture iB
allowed to react for two hours under these conditions. m e properties of the original copolyester (Example 41) and the modified copolyester (Example 42) are compared in the following table:
Example No. 41 42 ~ (1) 1610 2150 A (1) 473 880 Ratio Aw~ 3.40 2.44 -~
Inherent Viscosity (dl/gm) A) 0.5~ in tetrahydrofuran0.59 0.61 B) 0.3~ in chloroform 0.71 0.74 Glass Transition Temp. (C) -58 -56 Melt Temperature (C) ~42 ~42 Overlap tensile(2), kg/cm2 9.05 15.42 Acid Value 4.20 3.50 (1) ~ is the weight average polymer chain length in Angstrom units. ~ is the number average polymer chain length Nin Angstrom units.
; m ese were determined utilizing Gel Permeation Chromatography as described in "Preparative Methods of Polymer Chemistry", Second Edition, by Sorenson and Campbell, Interscience Publishers, New York.
... .
~:` (2)This tensile test is run at room temperature following the procedure of ASTM test D-1344-72 and using overlapped aluminum strlps adhered , over a 2.5 cm x 2.5 cm area with a 1.8 mm thick polymer sample.
Examples 43-44 ~; Advancement of a copolyester corrssponding in composition to that of Example 28 except using PTMEG2000 in :

in place of PTMEG630 is accomplished by adding 1.0 percent by weight of isophoronediisocyanate dropwise o~er a period of 15 minutes to the original polyester at 180 C. with stirring and in a nitrogen atmosphere then reacting for 2 hours under the same conditions. m e original copolyester had ~W 1200 and AN 200. The advanced copolyester had AW
2300 and A 320.

,. ~

.

., ~,~

... .

: .

. .

~ -25--.~. .

Claims (22)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A thermoplastic segmented copolyester capable of forming a strong, dependable bond to a substrate at a temperature below its melting temperature and without the involvement of volatiles consisting essentially of from about 5 to 75 percent by weight of amorphous ester units and 95 to 25 percent by weight of crystallizable ester units joined through ester linkages, the cry-stallizable ester units being of the formula:

and the amorphous ester units being of the formula:

wherein R1 consists of divalent radicals remaining after removal of the carboxyl groups from one or more saturated aliphatic dicarboxylic acids and/or aromatic dicarboxylic acids, R1 containing from 2 to 8 carbon atoms when it is an alipha-tic radical and being phenylene when it is an aromatic radical, R2 consists of divalent radicals remaining after removal of the hydroxyl groups from one or more saturated aliphatic diols containing from 2 to 12 carbon atoms, R3 is R
or R5, R4 is R2 or R6, R5 consists of the divalent radicals containing from about 22 to 50 carbon atoms which remain after removal of the carboxyl groups from saturated aliphatic dimer acids and R6 consists of the divalent radicals remaining after removal of the hydroxyl groups of long chain aliphatic diols having an average molecular weight of 200 to 4000, provided that at least one of R3 and R4 in each amorphous ester unit is R5 or R6, and provided also that when R1 is aromatic, R2 contains from 6 to 12 carbon atoms and the amorphous content is 50-75 percent by weight, the said copolymer having a DTA melting temperature from about 25 to 150°C., and an inherent viscosity of at least 0.5 dl/g at 25°C., as measured in 0.3 g/dl solutions of polymer in chloroform at 25°C., an open time of at least about 1/4 minute at 20°C., substantially com-plete solubility in toluene at 25°C. in the ratio of about 10 percent by weight of copolyester and 90 percent by weight of solvent, a tensile strength of 100-400 kg/cm, an elongation at break of 400-1000 percent,a T-peel adhesion to vinyl of at least 0.9 kg/cm of width and a DTA glass transition temperature, Tg, below -25°C.

2. A copolyester according to claim 1 wherein R1 is the divalent radi-cal of adipic acid, R2 is the divalent radical of 1,4-cyclohexanedimethanol, R3 is R1, and R4 is the divalent radical of poly (oxytetramethylene) glycols having molecular weights of about 2000, the copolyester varying in amorphous content from about 30 to 70 percent.

3. A copolyester according to claim 2 having from about 30 to 33 percent amorphous content.

4. A copolyester according to claim 2 having from about 45 to 55 percent amorphous content.

5. A copolyester according to claim 2 having from about 66-70 percent amorphous content.

6. A copolyester according to claim 1 wherein R1 is the divalent radical of adipic acid, R2 is the divalent radical of 1,4-cyclohexanedimethanol, R3 is R1 and R4 is the divalent radical of polyglycols having molecular weights of about 1000, the copolyester varying in amorphous content from about 25 to 65 percent.

7. A copolyester according to claim 1 wherein R1 is the divalent radical of adipic acid, R2 is the divalent radical of 1,4-cyclohexanedimethanol, R3 is the divalent radical of hydrogenated dilinoleic acid and R4 is the divalent radical of poly(oxytetramethylene)glycol having molecular weights of about 2000, the copolyester varying in amorphous content from about 30 to 65 percent.

8. A copolyester according to claim 7 having from about 40 to 65 percent amorphous ester units.

9. A copolyester according to claim 8 having from about 53 to 57 percent amorphous units and in which the weight ratio of glycol to diacid content is about 3:7.

10. A copolyester according to claim 1 wherein R1 is the divalent radical of terephthalic acid, R2 is the divalent radical of a linear aliphatic diol containing from six to twelve carbon atoms, R3 is R1 and R4 is the divalent radical of poly(oxytetramethylene) glycol having a molecular weight of about 2000, the copolyester varying in amorphous content from about 50 to 75 percent.

11. A copolyester according to claim 10 wherein R1 is the divalent radical of terephthalic acid, R2 is the divalent radical of 1,6-hexanediol, R3 is R1 and R4 is the divalent radical of poly(oxytetramethylene) glycol having a molecular weight of about 2000, the copolyester varying in amorphous content from about 60 to 75 percent.

12. A copolyester according to claim 11 of 68 percent amorphous content.

13. A copolyester according to claim 1 consisting essentially of about 25 to 75 percent by weight of amorphous ester units and 75 to 25 percent by weight of crystallizable ester units in which R1 is primarily tetramethylene, and/or phenylene, the copolyester having a DTA melting temperature of from about 65° to 150°C, and a DTA glass transition temperature below 0°C.

14. A method for forming a strong, dependable bond to a substrate without subjecting the substrate to high temperatures and without the involvement of volatiles which comprises:
(1) melting a solid, relatively strong thermo-plastic copolyester as defined in claim 1, (2) cooling the copolyester to below its melting temperature, (3) bringing the copolyester into contact with a substrate at a temperature below the copolyester melting temperature and while the copolyester is still open, and (4) maintaining the copolyester and the substrate in contact until the copolyester has reverted to its solid, non-bondable state.

15. A method according to claim 14 for forming a strong, dependable adhesive bond between substrate surfaces without subjecting the substrates to high temperatures and without the involvement of volatiles which comprises:
(1) melting the solid, relatively strong thermo-plastic copolyester, (2) cooling the copolyester to below its melting temperature, (3) forming an assembly comprising a bonding layer of the copolyester which is still open between the substrate surfaces which are below the melting temperature of the co-polyester, and (4) maintaining the assembly at a temperature below the melting temperature of the copolyester until the copolyester has reverted to its normal, solid, non-bondable state.

16. A method according to claim 14 wherein the substrate is maintained substantially at room temperature throughout the bonding operation.

17. A sheet backing provided on at least one major sur-face with a thermoplastic, coherent layer which essentially comprises a segmented copolyester according to claim 1.

18. A composite tape-like product according to claim 17 capable of being wound upon itself in roll form and subsequently unwound without delamination or transfer comprising a flexible sheet backing having adhered thereto over one major surface a thermoplastic, coherent layer which essentially comprises a segmented copolyester.

19. A composite tape-like product according to claim 18 comprising in combination a self-supporting smooth web and, releasably adhered to one face of said web, an adhesive film whereby when the adhesive is heated above its melting point, the exposed surface thereof may be adhered to a structure to be bonded, the web removed without disrupting the adhesive film, a second structure applied to the newly exposed adhesive surface and temporarily adhered thereby to the first structure and held until the adhesive has hardened to permanently bond said structures together, said adhesive film consisting essentially of a thermoplastic segmented copolyester.

20. A composite tape-like product according to claim 19 wherein the adhesive film comprises a copolyester wherein R1 is the divalent radical of adipic acid, R2 is the divalent radical of 1,4-cyclohexanedimethanol, R3 is the divalent radical of hydrogenated dilinoleic acid, and R4 is the divalent radical of poly(oxytetramethylene) glycol having a molecular weight of about 2000, the copolyester having from about 53 to 57 percent amorphous units and in which the weight ratio of glycol to diacid content is about 3:7.

21. A composite tape-like product according to claim 19 wherein the adhesive film comprises a copolyester wherein R1 is the divalent radical of terephthalic acid, R2 is the divalent radical of 1,6-hexanediol, R3 is R1 and R4 is the divalent radical of poly(oxytetramethylene)glycol having a molecular weight of about 2000, the copolyester having 68 percent amorphous units.

22. A fiber-reinforced thermoplastic adhesive film com-prising in combination a fibrous web provided on at least one major surface with a thermoplastic segmented copolyester accord-ing to claim 1.