COPOLYESTER ADHESIVE BLEND

Abstract: Copolyester adhesive blends for use particularly as fabric blends. The blends comprise a crystallizable copolyester and a substantially amorphous polyester.

Description: COPOLYESTER ADHESIVE BLEND This invention relates to certain copoiy¬ ester blends which have been found to be useful as adhesives, especially for bonding fabric, fibers and the like. Fabric adhesives are often used on fusible interlinings, which are materials such as fabric which have been coated on one side with a dis¬ continuous pattern of adhesive. When the interlining is bonded to a face fabric in a garment, it provides body and shape to the garment without impairing the ability of the fabric to breathe. Fusible inter¬ linings are used in the manufacture of suits, in shirt collars and cuffs, and in the waistbands of trousers. In the manufacture of suits, polycarbonate basting threads are frequently used to temporarily hold the parts of the suit in place. After the suit is completed, a solvent such as perchloroethylene or trichloroethylene is used to embrittle the poly- carbonate thread so that it may be brushed from the fabric. Binder fibers are used with nonwovens, which are formed from matrix fibers into a web, sheet, or mat. The binder fibers give strength to the wet, mat, or sheet by bonding it together. Certain polyesters are known to be useful for fusible interlining adhesives and binder fibers. However, these polymers also tend to have certain disadvantages. For example, one polyester of inter¬ est is the copoiyester of terephthalic acid, adipic acid, ethylene glycol and 1,4-butanediol as described in U.S. Patent No. 3,699,921. Such polyesters tend to block in pellet form and fumed silica must be added in significant amounts to make it possible to grind this polymer into powder. Excessive amounts of fumed silica in the powder, however, prevent good coatability and good fusion of the powders on the fusible interlining fabric when applied with powder point applicators• Thus, these adhesives are not easily applied. Amorphous polyesters cannot be used as fusion adhesives in which resistance to dry-cleaning agents and high set-up speed are required. In like manner, those polyesters are undesirable which have too little crystallinity, because they solidify too slowly and consequently do not lose their surface stickiness for long periods of time. Certain low melting, crystailizable poly¬ esters are useful for bonding fabrics at temperatures (120-150°C) which do not damage the f brics. These bonds generally show excellent resistance to laun¬ dering and dry cleaning treatments. Thus, these materials are useful in film, fusible interlining, or melt blown web form to laminate fabrics in the con¬ struction of wearing apparel. However, in applica¬ tions where high temperature resistance is required, the low melting polyesters are not completely satis- factory. In U.S. Patent 4,131,714 there is described an adhesive composition which is a blend of a crys¬ talline polyester having a very high melting point, e.g., 243°C, and an amorphous polyester. The blend is used as a solution in an organic solvent usually cresylic acid. This alone makes the composition not useful as a fabric adhesive which must be a solid, e.g., a powder. Further, the cresylic acid is prob¬ ably necessary .r order to provide a plasticizer for the very high melting crystalline polyester used so as to make the composition usable at reasonable tem¬ peratures. Cresylic acid would be unsuitable in a fabric adhesive because it would attack the fabric and could irritate the skin of a wearer of the fab- ric. The compositions of this patent are used in electrical equipment. OMPI Thus, the problem to be solved is to provide a fabric adhesive which is easily applied to fabrics and which shows good high temperature resistance. This problem is solved by providing a particulate blend of a) a crystailizable copoiyester having a melting point of 80-130°C and a glass transition temperature between 0°C and 20°C and b) a substantially amorphous copoiyester having a glass transition temperature of 50°C or higher. The blends contain 10-99%, preferably 95%, of the crystailizable copoiyester and 90-1%, prefer¬ ably 70 to 5% of the substantially amorphous copoiy¬ ester. Useful crystalline polyesters are derived from an acid selected from the group consisting of terephthalic acid and 1,4-cyclohexanedicarboxylic acid and a glycol selected from the group consisting of 1,4-butanediol, 1,6-hexanediol and mixtures of 1,4-butanediol and 1,6-hexanediol, the copoiyester also being derived from about 20-60 mole percent of a co-acid or a co-glycol, or about 20-75 mole percent of a combination of a co-acid and a co-glycol, the co-acid and co-glycol being selected from the group consisting of isophthalic acid, C 3 -C12 ali¬ phatic dibasic acids, aliphatic and cycloaliphatic glycols having 2-8 carbon atoms and diethylene gly¬ col. These polyesters preferably have a heat fusion of 1-10 calories per gram and I.V. (inherent viscos- ity) of 0.4-1.2, preferably between 0.75 and 0.95. Crystailizable copolyesters of particular interest include 1) ρoly(butylene terephthalate) co¬ polyesters containing 20 mole percent glutaric acid and 45 mole percent diethylene glycol, 2) poly(butylene terephthalate) copolyesters containing 30 mole percent glutaric acid and 45 mole percent OM?I diethylene glycol, 3) poly(butylene terephthalate) copolyesters containing 25 mole percent glutaric acid and 40 mole percent diethylene glycol, 4) ρoly(hexa- methylene terephthalate) copolyesters containing 20 mole percent isophthalic acid and 20 mole percent 1,4-butanediol, 5) poly(hexamethylene terephthalate) copolyesters containing 10 mole percent isophthalic acid and 40 mole percent 1,4-butanediol, 6) poly(hexamethylene terephthalate) copolyesters con- tainiπg 20 mole percent 1,4-butanediol, 7) poly(butylene terephthalate) copolyesters containing 50 mole percent isophthalic acid, 8) poly(butylene 1 ,4-cyclohexanedicarboxylate) copolyesters containing 25 mole percent glutaric acid and 25 mole percent diethylene glycol, 9) poly(hexamethylene tere¬ phthalate) copolyesters containing 20 mole percent glutaric acid and 20 mole percent diethylene glycol and the like. Useful amorphous copolyesters are derived from at least one acid selected from the group con¬ sisting of terephthalic acid, isophthalic acid, and 1,4-cyclohexanedicarboxylic acid, and at least one glycol selected from the group consisting of ethylene glycol, diethylene glycol, and 1,4-cyclohexane- di ethanol, with the proviso that the copoiyester contains at least two acids or at least two glycols , the second acid or glycol being present in an amount of 25-60 mole percent. Substantially amorphous copolyesters of particular interest include polyesters having Tg values above 50°C, preferably 50-90°C, heats of fusion ΔHf of less than one calorie per gram and inherent viscosities of 0.4 to 1.2. Some typical polymers include 1) poly(ethylene terephthalate) co- polyesters containing 31 mole percent 1,4-cyclo- hexanedimethanol, 2) poly(l ,4-cyclohexylenedi- methylene terephthalate) copolyesters containing 40 mole percent ethylene glycol, 3) poly(l,4-cyclo- hexylenedi ethylene terephthalate) copolyesters con¬ taining 50 mole percent isophthalic acid, 4) poly(ethylene isophthalate) copolyesters containing 50 mole percent 1,4-cyclohexanedimethanol, 5) poly(ethylene 1,4-cyclohexanedicarboxylate) copoly¬ esters containing 50 mole percent 1,4-cyclohexane¬ dimethanol, 6) poly(ethylene terephthalate) copoly- esters containing 37 mole percent diethylene glycol, and the like. The low melting, crystailizable copolyesters and substantially amorphous, high Tg copolyesters may be used in the form of powder blends or pellet • blends. In general, the concentration of high Tg polyester present may range from about 1 to about 90 weight percent but the preferred range is about 5 to about 70 weight percent. A preferred blend is one wherein the crystailizable copoiyester has an I.V. of 0.75-0.95 and is derived from 60-80 mole percent terephthalic acid, 40-20 mole percent glutaric acid, 45-65 mole percent 1,4-butanediol and 35-55 mole per¬ cent diethylene glycol, and said substantially amor¬ phous copoiyester has an I.V. of 0.45-0.80 and is derived from at least 80 mole percent terephthalic acid, 60-80 mole percent ethylene glycol and 40-20 mole percent 1,4-cyclohexanedimethanol, said mole percentages being based on 100 mole percent dicar- boxylic acid and 100 mole percent glycol, and each of said copolyesters being present in amounts within the range of 30-70 weight percent based on their combined weight. A typical crystailizable copoiyester useful in this invention is as follows : Fifty-three and thirty-five hundredths grams of dimethyl terephthalate (0.275 mole), 36 grams (0.225 mole) of OMPI dimethyl glutarate, 55.35 grams (0.615 mole) of 1,4- butanediol, 40.8 grams (0.385 mole) of diethylene glycol, and 1 mL of n-butanol solution of titanium tetraisopropoxide which is 1.24 weight percent tita- niu are weighed into a 500-mL single-neck round- bottom flask equipped with a nitrogen inlet, stirrer, vacuum outlet, and a condensing flask. The flask is heated at 200°C for three hours with a nitrogen sweep over the reaction mixture. When the theoretical amount of methanol has distilled from the reaction mixture, the temperature is increased to 255°C at a reduced pressure of 0.5 to 0.1 mm of mercury for one hour. The flask is then removed from the heat and allowed to cool as the polyester crystallizes. Gas chromatographic analysis of the hydrolyzed copoiy¬ ester reveals the copoiyester contains the following mole percentages of reaction residues: dimethyl terephthalate, 55 mole percent; dimethyl glutarate, 45 mole percent; 1,4-butanediol, 70 mole percent; and diethylene glycol, 30 mole percent. The copoiyester has an inherent viscosity of 1.0 and a crystalline melting point of 115°C (DSC) . The crystallization half time of this copoiyester is 1.2 minutes at 60°C. The copoiyester is an excellent fabric adhesive. Other crystailizable copolyesters may be made using the same technique, as is well known in the art. Typical substantially amorphous ccJpolyesters which may be used in accordance with this invention are commercially available. For example, 0DAR PETG copoiyester 6763, product of Eastman Chemical Products, Inc., a copoiyester of terephthalic acid and ethylene glycol modified with 1,4-cyclohexane¬ dimethanol is particularly useful. Such substan- tially amorphous polyesters may be produced in accor¬ dance with known techniques, such as taught in U.S. Patent 2,901,466. S ^__ OMPI The copolyesters prepared as described above, are individually cryogenically ground, mixed and screened using conventional procedures to obtain a powder that will pass a 70-mesh screen (200 micro- meter particles). The powders may be applied from an engraved roll to an interlining fabric to form an interlining containing rows of adhesive dots across the interlining fabric. The interlining is used to bond two different face fabrics in the examples , wool/polyester and polyester/cotton. Unless other¬ wise indicated, the interlinings are bonded to face fabrics by pressing 10 cm squares of interlining to 10 cm squares of face fabric using either steam or an electric press. The bonded fabrics are laundered and dry cleaned, then cut into strips one-inch wide and T-peel strengths reported are an average of three determinations per sample. The crystalline melting point, ΔHf, and T referred to above are measured by conventional a means using a Differential Scanning Calorimeter. Ester-forming derivatives of the acids referred to herein can be employed, if desired, to prepare the copolyesters of this invention. Examples of such ester forming derivatives are the anhydrides, esters and ester chlorides of such acids. These copolyesters are readily put into powder form using conventional grinding techniques , preferably by cryogenic grinding. The powders are nonblocking and can be readily applied to fusible interlining fabrics from powder point applicators, from random sprinkling equipment, or in the form of a paste. The particles are finely divided, i.e., from about 1 micrometer to about 500 micrometers. In the application of powders from powder point applicators, it is desirable to have powders with a particle size range of 50-200 micrometers (200-70 mesh) . For ran¬ dom sprinkling application on tightly woven or non- OMFI woven fabrics, particle size of 150-300 micrometers (100-50 mesh) is desirable. For random sprinkling on open-weaver fabrics such as rayon/cotton blends, powders with 300-500 micrometer size (50-35 mesh) are required. For application of powder in paste form, it is necessary to have very fine powders. For exam¬ ple, in paste form, powder size should be 1-80 micro¬ meter (less than 200 mesh) . In the case of binder fibers, such fibers can be produced using conven- tional spinning techniques well known in the art. The copolyesters may also be used in other forms , such as a film. The "heat of fusion", ΔH^, of polymers is the amount of heat absorbed when crystailizable polymers are melted. ΔH^ values are readily obtained using Differential Scanning Calorimeters (DSC) (Perkins-Elmer). For example, one method for determining ΔH^ is described in Journal of Applied Polymer Science, 20 1209 (1976) . Measurement of ΔHf is also described in DuPont Thermal Analysis Bulletin No. 900-8 (1965). Qualitatively, it is possible to compare the degree of crystallinity of polymers by comparing their ΔH^ values. When copolyesters prepared as described above are employed as melt adhesives to laminate various fabric systems, metal strips and the like, excellent bonds result. These bonds are found to be highly resistant to the action of dry cleaning sol¬ vents such as perchloroethylene. The strength of the bonds is determined by a peel test based on the ASTM "T-Peel Test" set forth on pages 609-611 of the 1972 edition of the BOOK OF ASTM STANDARDS, published by the American Society for Testing Materials, and more specifically identified as Test Number D-1876-69. Results are averages of three specimens . -ftTRl OMPI If desired, dyes or dye receptive agents, color stabilizers and various other adjuvants may be added to the copoiyester adhesives to meet certain specific end use requirements. Such additives would normally be added as such to the polymerization mix¬ ture in which the copoiyester is produced. As used herein, the inherent viscosity (I.V.) is measured at 25°C using 0.50 gram of copoiy¬ ester per 100 ml. of a solvent consisting of 60 per- cent by weight phenol and 40 percent by weight tetra- chloroethane. The following examples are submitted for a better understanding of the invention. EXAMPLE 1 A poly(butylene terephthalate) copoiyester containing 30 mole percent glutaric acid and 45 mole percent diethylene glycol (Polymer A) having an in¬ herent viscosity of 0.85 dL/g (measured in 60/40 phenol-tetrachloroethane solvent) is cryogenically ground in a Pulverizer with liquid nitrogen. The powder is screened through U.S. Standard sieves to give particles of 40 to 70 mesh size (coarse powder) • A poly(ethylene terephthalate) copoiyester containing 30 mole percent 1,4-cyclohexanedimethanol (Polymer B) having an inherent viscosity of 0.60 dL/g is cryogenically ground and sieved as described above to provide powder having a particle size of 40-70 mesh. Equal weights (100 g) of the coarse powder of each of these two copolyesters are dry blended in a polyethylene bag by rotating and shaking the bag for five minutes. The coarse powder blend is randomly sprin¬ kled on a bonded polyester nonwoven pad to give a uniform coating weight of 20 grams per 930 cm 2 . The coated pad is placed in an air oven at 177°C for about three minutes to lightly fuse the powder. Less than 1% of the powder remains unfused after this treatment. The coated pad 10 cm x 15 cm is bonded to a 10 cm x 15 cm fabric backed poly(vinyl chloride) sheeting on a Sentinil heat sealer (both platens heated; platens are 2.54 cm wide) at a bonding temperature of 155°C for 10 seconds at 1619 gm/cm 2 gage bonding pressure to give a 15 cm wide bond. The bond is quenched immediately on a stone bench top. Five cm are trimmed from each end of the bond and three one-inch T-peel bonds are cut from each sam¬ ple. These T-peel bonds are tested on an Instron machine at 20 cm/min. crosshead speed. Bonds made with the powder blend have an average peel strength of 2270 gm/linear cm at 23°C and 1394 gm/linear cm at 80°C. Similar bonds made with Polymer A coarse powder (no loss of powder after being fused on the pad) give an average peel strength of 1750 gm/linear cm at 23°C but at 80°C the average peel strength is only 107 gm/linear cm. When attempts are made to fuse unmodified coarse powder of Polymer B on the nonwoven pad, much of the powder is unfused and the powder falls off the pad. This unmodified Polymer B is not useful in this bonding application. Thus, this example illustrates that the powder blend composition provides good fusing prop- erties and good peel strength at both 23°C and 80°C. Equally good bonds are obtained when the nonmono er pad is bonded to the fabric backed vinyl material using dielectric sealing equipment instead of a heat sealer. EXAMPLE 2 The procedure of Example 1 is repeated ex¬ cept that Polymer B is replaced with a poly(1,4- C tFI cyclohexylenedi ethylene terephthalate) copoiyester containing 40 mole percent ethylene glycol (Polymer C) . Bonds made with a powder blend of equal weights of Polymer A and Polymer C give an average peel strength of 2500 gm/linear cm at 23°C and 1770 gm/linear cm at 80°C. EXAMPLE 3 The procedure of Example 1 is repeated ex¬ cept that Polymer B is replaced with a poly(ethylene terephthalate) copoiyester containing 37 mole percent diethylene glycol (Polymer D) . Bonds made with a powder blend of equal weights of Polymer A and Poly¬ mer D give an average T-peel strength of 1966 gm/linear cm at 23°C and 1555 gm/linear cm at 80°C EXAMPLE 4 The procedure of Example 1 is repeated except that Polymer B is replaced with a poly(eth¬ ylene isophthalate) copoiyester containing 50 mole percent 1,4-cyclohexanedimethanol (Polymer E) • Bonds made with a powder blend of equal weights of Polymers A and E give an average T-peel strength of 2502 gm/linear cm at 23°C and 2073 gm/linear cm at 80°C. EXAMPLE 5 The procedure of Example 1 is repeated ex- cept that the powder blend is composed of 75 weight percent Polymer A and 25 weight percent Polymer B. Bonds made with this blend give an average T-peel strength of 2020 gm/linear in at 23°C and 536 gm/linear cm at 80°C EXAMPLE 6 The procedure of Example 1 is repeated ex¬ cept that Polymer A is replaced with ρoly(hexa- ethylene terephthalate) copoiyester containing 20 mole percent isophthalic acid and 20 mole percent 1,4-butanediol (Polymer F) . Polymer F has a melting point of 104°C, ΔH^ of 6.3 cal/g and an inherent viscosity of 0.72. Bonds made with a powder blend of equal weights of Polymer B and Polymer F give an average T-peel strength of 2467 gm/linear cm at 23°C and 500 gm/linear cm at 80°C. EXAMPLE 7 The procedure of Example 1 is repeated ex¬ cept that equal weights of pellets of Polymers A and B are cryogenically coground in the pulverizer rather than being ground separately. Bonds made with coarse powder (40-70 mesh) of the coground powder give an average T-peel strength of 2341 gm/linear cm at 23°C and 1376 gm/linear cm at 80°C. EXAMPLE 8 A pellet blend (0.32 cm pellets) of 10 weight percent Polymer B and 90 weight percent Poly¬ mer A is prepared in a V-Cone mixer by mixing for two hours. The pellet blend is extruded into 3 mil film on a 4.5 cm, 24/1 Prodex extruder at a melt tempera¬ ture of 310°F. (155°C) and with a take-up roll main- tained at 80°F (27°C) The pellet blend provides film that sets up faster and gives significantly less sticking to the chill roll than that obtained with Polymer A. The faster set up of the pellet blend in extruded film form and reduced sticking to the chill roll allows the film to be extruded at a faster rate. Polyester/cotton twill fabric is bonded with samples of this 3-mil film at 150°C on a Sentinel Heat Sealer. The bonds have a peel strength of 3664 gm/linear cm and are resistant to laundering and dry cleaning treatments. Bonds were also made at 130°C and a peel strength of 2588 g/linear cm was obtained. Similarly good results are obtained with a pellet blend of 1.0 weight percent of Polymer B and 99.0 weight percent of Polymer A. CMPI EXAMPLE 9 The procedure of Example 1 is repeated ex¬ cept that the powders of Polymer A and Polymer B are sieved to a particle size of 70-200 mesh (medium powder) . A powder blend of 85 weight percent of medium powder of Polymer A and 15 weight percent of medium powder of Polymer B are dry blended in a poly¬ ethylene bag by tumbling and rotating the bag for five minutes • Powderpoint fusible interlinings are pre¬ pared with this medium powder blend on a small-scale laboratory powderpoint machine. The powder is ap¬ plied (21.7 gm/m 2 ) from an engraved roll to a cotton interlining fabric to form an interlining con- taining rows of adhesive dots across the interlining fabric (34.9 dot ' s/cm 2 ). The interlining is used to bond a polyester/cotton face fabric. The inter¬ linings are bonded to the face fabrics by pressing four-inch squares of interlining to four-inch squares of polyester twill face fabric using an electrically heated garment press at 150°C. The bonded fabrics are laundered and dry cleaned, then cut into strips one inch wide. T-peel strengths are determined before and after laundering and dry cleaning• The T-peel strengths reported are an average of three determinations per sample. An initial peel strength of 429 gm/linear cm at 23°C (30.5 cm/minute testing rate) is observed. After commercial dry cleaning, the bonds have a peel strength of 322 gm/linear cm. After laundering treatments, the bonds have a peel strength of 322 gm/linear cm. Bonds were also made at 120°C and a peel strength of 268 g/linear cm was obtained. EXAMPLE 10 A pellet blend of 5.0 weight percent Polymer B and 95.0 weight percent Polymer A is prepared in a V-cone mixer by blending for two hours . The pellet blend is fed from an extruder into a gear box and through a 0.3 mm spinning orifice at 270°C. An air cavity surrounds the spinning orifice and air at the temperature of the orifice is exited at high pressure at the orifice tip drawing the polymer down and cooling it and causing a melt blown web to form. The melt blown web is taken up on a silicone treated release paper. The web has a weight of 43.4 g/m 2 . Bonds (10 cm x 15 cm) of polyester/cotton twill are made with the web at a temperature of 150°C for 15 seconds on an electricaly heated garment press. The 10 cm x 15 cm 4" x 6" bonds are cut into 2.5 cm x 15 cm pieces and tested on an Iπstron machine at 12 in/min. The results are the averages of three measurements. The web from the pellet blend gives a T-peel strength of 1609 gm/linear cm. EXAMPLE 11 A polyester nonwoven web is formed by passing polyester staple fiber through a Textile Card machine to give a web weight of 13.7 gm/m 2 . Medium powder (70-200 mesh) of a 90/10 powder blend of Poly¬ mer A and Polymer B is fluidized with nitrogen and sprayed on the web with an electrostatic gun to give a uniform coating. The web is passed through a heating chamber of infrared heaters to fuse the adhesive powder and then 3.42 through calendering rolls. The weight of adhesive in the web is 3.42 oz/yd 2 . The web has a nice soft hand and is strong and uniformyl bonded in both the machine and trans¬ verse directions. Unless otherwise specified, all parts, per¬ centages, ratios, etc. , are by weight.

Claims: Claims 1. Adhesive compositions comprising a blend of a) a crystailizable copoiyester having a melting point of about 80-130°C and a glass transi¬ tion temperature between 0°C and 20°C and b) a substantially amorphous copoiyester having a glass transition temperature of 50°C or higher. 2. Adhesive compositions according to claim 1 wherein said crystailizable copoiyester has an I.V. of about 0.75-0.95 and is derived from about 60-80 mole percent terephthalic acid, about 40-20 mole percent glutaric acid, about 45-65 mole percent 1,4-butanediol and about 35-55 mole percent di¬ ethylene glycol, ' and said substantially amorphous copoiyester has an I.V. of about 0.45-0.80 and is derived from at least 80 mole percent terephthalic acid, about 60-80 mole percent ethylene glycol and about 40-20 mole percent 1,4-cyclohexanedimethanol, said mole percentages being based on 100 mole percent dicarboxylic acid and 100 mole percent glycol, and each of said copolyesters being present in amounts within the range of 30-70 weight percent based on their combined weight. 3. Adhesive compositions according to claim 1 comprising about 30 to about 95 percent by weight of said crystailizable copoiyester and about 5 to about 70 percent by weight of said substantially amorphous copoiyester. 4. Adhesive compositions according to claim 1 in the form of a powder blend and having a particle size of about 1-500 micrometers. 5. Adhesive compositions according to claim 1 in the form of a film. OMPI_ 6. Fabric material bonded together with the adhesive composition of claim 1. 7. Substrate material having a coating thereon comprising the composition of claim 1.

Inventors: MCCONNELL RICHARD LEON, MEYER MAX FREDERICK JR, MCCONNELL, RICHARD, LEON, MEYER, MAX, FREDERICK, JR.
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1983
Main classification: C09J3
IPC codes: C09J167