Title of Invention	A PROCESS FOR MANUFACTURING A CROSSLINKABLE HOT-MELT ADHESIVE COMPOUND
Abstract	The present invention relates to a process for manufacturing a crosslinkable hot-melt adhesive compound for coating and/or laminating surface formations, characterized in that the crosslinking constituent is micro-encapsulated by a silanized polybutadiene and the reactive constituents are first caused to react in the melt by crosslinking.

Full Text

The present invention relates to a process for manufacturing a cross-linkable hot-melt adhesive compound based on an aqueous paste comprising a micro-encapsulated polyisocyanate dispersion and a commercially available amine-terminated copolyamide or copolyester for manufacturing a base dot as a strike back barrier in double dot coating. The upper dot comprises an amine-regulated copolyamide for ensuring good bonding to the lower dot. The invention relates in particular to a hot-melt adhesive compound for a grid-like coating of flxable interlining materials for the garment industry, in particular for outerwear. The following can be used in place of the copolyamide: OH group terminated copolyesters based on terephthalic acid, isophthalic acid and butane diol or butane diol in combination with small quantities of up to 12 molar %, preferably from 6 to 10 molar %, of other diols such as for example hexane diol or polyethylene glycol, having melting points of 100 to 150°C. In the interests of solving the problems of reduced washing and dry cleaning resistance as well as weaker adhesion, improved hot-melt compounds have been developed, as have improved coating technologies. Duo dot or double dot coatings are described in patents DE B 22 14 236, DE-B 22 31 723, DE-B 25 36 911 and DE-B 32 30 579 for example. The coating carriers were improved according to the state of the art in that finer yarns with fine-denier single fibers including the microfiber range and synthetic yams such as high bulk acrylic or polyester yarn are used. The fabrics originally used have been replaced extensively by stitch-bonded fabrics, wherein the latter materials represent a combination of nonwoven and woven fabrics. These novel combinations result in very soft though very open structures which place higher demands on coating methods and hot-melt adhesive compounds, in particular with respect to strike back and bleed-through of the hot-melt adhesive compound. Due to costs and quality reasons, there has been a noticeable drop in the coating quantity applied per m of interlining material. Whereas previously coating quantities of 15 to 20 g/m2 were common, nowadays they are 7 to 12 g/m2. Despite these small quantities, adequate adhesion and fastness must be guaranteed, that is, the hot-melt adhesive may not penetrate into the interlining, otherwise it is no longer available for actual adhesion. The aim of the invention was to find an effective strike back barrier which exhibits high bonding strength, good bonding of the upper dot on the base layer and good washing and dry cleaning resistance as well as having a sterilizing capacity, with a reduced quantity of coating material. A further advantage is that a higher level of thermal stability under load is achieved. According to the state of the art, a range of strike back barriers is known, such as crosslinking acrylate or polyurethane dispersions or powder-filled pastes based on high-melting copolyamides and polyethylene or high-viscosity thermoplastic polyurethane powder. All these systems have more or less major disadvantages when applied to rough, napped interlinings and in their bonding to the upper dot or their wash-resistance. In the case of coating of self-crosslinking acrylate or polyurethane dispersions, partial crosslinking frequently occurs during coating, which may result in a coating forming on the template and thus a blockage of the template holes. Extensive cleaning of the plant is then required. When production-related downtime occurs, this can also cause major difficulties and disturbances to the point where the templates become unusable. Also, when the material is being applied, bonding of the upper dot to the base layer is a problem. The high-viscosity powder-filled systems based on polyamide, polyethylene and polyurethane generally do not satisfy the resistance to strike back that is required. To date there has been no success in creating a stable crosslinked system for the base dot. The isocyanates preferably used were unable to be stabilized against water (matrix for coating pastes) or the activation temperatures required for crosslinking (greater than 150°C) were excessive. For special applications where the activation temperature can be higher (>150°C), for example for fixing shirt collars, internally blocked polyisocyanates, e.g. dimerized polyisocyanates, may be employed. Powder mixtures of this polyisocyanate and the amine-terminated copolyamide or copolyester can also be processed by means of other application techniques such as powder dispersion or powder dot. According to the state of the art to date, polyethylene with melting points of 110°C to 120°C or higher-melting polyamides in the melting range of 130°C to 160°C have been used for fixing shirt collars. Isocyanate had to be stabilized against water or against diffusion of humidity to ensure activability at relatively low temperatures. The object of the present invention was to find an effective strike back barrier which exhibits high bonding strength, good bonding of the upper dot on the base layer even on rough bases and good washing and dry cleaning resistance as well as a sterilizing capacity with a reduced quantity of coating material. Another object was to attain increased thermal stability under load for the hot-melt adhesive coating and to facilitate processing of the dispersions, as well as preventing the templates from becoming blocked. An additional object of the invention was to clearly improve the sensitivity of the isocyanate to humidity. This task was solved as claimed in the claims in that the isocyanate, having more than 2 free NCO groups and a melting range of 110 to 130°C, e.g., trimerized polyisocyanate products, were added to the paste formulation in micro-encapsulated form. Silanized polybutadiene, which forms stable and water-impermeable capsules on contact with water or moist steam atmosphere, is suitable as a capsule material. It is known that silanized polybutadienes may be employed for micro-encapsulation, but their applicability in conjunction with isocyanates and amines was surprising. It would have been assumed that isocyanate or amine and silane react with one another so that the isocyanate for generating the hot-melt adhesive is deactivated or destroyed and no longer available for hot-melt adhesive formation in accordance with the intended use. It would also have been assumed that isocyanate and the moist medium required for crosslinking or generating the capsule structure of the silanized polybutadiene in situ is damaging to the isocyanate in that it immediately hydrolizes. According to the solution according to the present invention it was surprising that isocyanates are very sluggish in reaction vis-a-vis the silane and that microcapsules can be formed. In addition to this, micro-encapsulation obviously occurs so rapidly that hydrolysis of the isocyanate is entirely prevented and moisture, which might damage the isocyanate, is prevented from penetrating into the microcapsule. The microencapsulated isocyanates are manufactured by mixing the isocyanate constituent with the silanized polybutadiene. The mixing temperature is adjusted to the melting points of the constituents and as a rule is at 100°C to 150°C. The crosslinking constituent with the silanized polybutadiene in a ratio of 4:2 to 4:1, preferably 4:1, are charged. The polybutadiene should exhibit a silicon content of 2 to 10% by weight, a molar mass of 1500 to 2500 g/mol, a viscosity of 1000 to 3000 mPas and a solids content of greater than 60%. The mixing procedure runs under high shearing. Added to the mixture are another approx. 0.5 to 1.5% of a commercial surfactant (e.g. Intrasol), 0.05 to 0.1% of a catalytic acid (e.g., toluenesulfonic acid) and 1.5 to 5% of a thickener (e.g., acrylic acid ester thickener) and other additives, if required. The crosslinkable hot-melt adhesive compound according to the present invention for coating and/or laminating of surface formations is characterized in that the reactive constituents present in the hot-melt adhesive compound first react in the melt with crosslinking. The crosslinking constituent is added to the coating paste in the form of a microencapsulated polyisocyanate dispersion. In this preferred initial form, a commercial copolyamide with amino end groups with a trimerized diisocyanate rendered nonsensitive to water is processed into a paste. The material to be processed is then coated by means of rotary screen-printing. A copolyester may be used in place of the copolyamide. During subsequent drying in an oven at approx. 120°C crosslinking is introduced within a few seconds to obtain a crosslinked strike back barrier for the double dot. In this way the usual problems of systems containing isocyanate can be circumvented; by way of example, these comprise the fact that capped isocyanates (caprolactam or oximes as encapsulation media) require excessively high activation temperatures. It is also an advantage that no low-boiling inflammable solvents are released during fixing, since there is an aqueous suspension present. Example 1: 160 g of 70% polyisocyanate solution of a trimerized IPDI are mixed together with 40 g of a silanized polybutadiene having a molar mass of 1500 to 2500, a viscosity of 1000 to 3000 mPas and a solids content > 60%. The result is a clear homogenous mixture. This mixture is added slowly into an aqueous solution comprising 500 g water, 10 g Intrasol, 0.5 g p-toluenesulfonic acid, 1 g defoaming agent and 30 g of a commercial aqueous thickener under high shearing by means of a stirring apparatus which generates high shear forces (Ultra-Thurrax). Under hydrolysis conditions the capsule-forming material immediately encapsulates the polyisocyanate by forming a waterproof shell that can be destroyed or released by pressure or heat as per the intended use. The dispersion or the print paste generated in this manner now has particularly advantageous properties: The paste, which is printed as a base dot (strike back barrier) for the so-called double dot, crosslinks during drying in the attached hot-air duct and melts with the scattered amine-terminated copolyamide (upper dot). Bonding is particularly good because the amino end groups from the upper dot, at the boundary surface to the base dot, can react with the crosslinking constituent, resulting in a fluent transition from the crosslinked base layer to the thermoplastic upper dot which guarantees actual adhesion. To attain particularly good bonding of the upper dot on the base dot, it is advisable to use an amine-regulated copolyamide as the upper dot material. Appropriate products for the base and upper dot are low-viscosity, low-melting grades. The melting point should be between 90 and 150°C, preferably between 115 and 130°C, with a solution viscosity in the range of 1.2 to 17 mPas, preferably 1.25 to 1.4 mPas. The boundary layer thereby reacts with the isocyanate paste and creates a very resistant connection of both dots. The coating quantities for the base dot should be 2 to 5 g/m2, preferably 2.5 to 4 g/m2, for the upper dot according to application, 4 to 8 g/m2, particularly 5 to 7 g/m2. The base dot can be applied grid-like as a paste. Internally blocked polyisocyanates (e.g., dimerized polyisocyanate) can also be processed Without being encapsulated in paste because they are not susceptible to water. The use of such systems is limited to a temperature range above 150°C, for example for shirt collars, because the textiles being used here, generally cotton, tolerate higher temperatures. A paste formula, VESTAMELTX 1316-P 1 (Degussa Huls), is suitable as a hot-melt adhesive. Example 2 An amine-terminated copolyamide of Degussa-Huls AG (VESTAMELT X 1027-P 1) and an encapsulated polyisocyanate dispersion manufactured inlhe above-mentioned manner were processed into a printable paste with commercially available dispersing agents and thickeners, e.g., Intrasol 12/18/5 and Mirox TX marketed by Stockhausen, and as described in DE-B 20 07 971, DE-B 22 29 308, DE-B 24 07 505 and DE-B 25 07 504, and printed using a rotary screen printer with a CP 66 template on a 35 g polyester fabric with high bulk yarn. The coating was 2 g/m2. VESTAMELT X 1027-P816 was scattered on the still wet paste dot, the excess was suctioned up and the article was dried and sintered in a drying oven at 130°C. The upper dot had a coating of 5 g/m2, making the total weight 7 g/m2. Paste formulation of the base dot: 1500g Water 35 g Mirox TX (polyacrylic acid derivative) 40 g Intrasol 12/18/5 (ethoxylated fatty alcohol) 200 g polyisocyanate dispersion (approx. 5% trimerized IPDI) from Example 1 600 g VESTAMELTX1027-P1 The amine-terminated VESTAMELT X 1027-P816 of Degussa-Huls AG was scattered as a scattering material. Result: A 5 cm wide strip of this interlining was fixed to a siliconized blouse material from a cotton/polyester mix at a joint temperature of 127°C for 10 s and a linear pressure of 4 N, after which the composite was subjected to a 60°C wash. Primary adhesion: 16 N / 5 cm 60°Cwash: 14 N/5 cm Back riveting: 0.1 N /10 cm On Example II: Comparison to state of the art A paste system based on copolyamide polyethylene was applied to the same interlining base and scattered with the same upper dot material, then dried and sintered. The same quantities of base dot and upper dot were applied. Paste formulation: 1500 g Water 35g Mirox TX 40 g Intrasol 12/18/5 400 g SCHAETTIFIX 1820 (high-density polyethylene) 200 g VESTAMELT X751-P1 The SCHAETTIFIX 1820 is a high-density polyethylene with a melting point of 128 to 130°C and a melt index of 20 g/10 min. Result: Primary adhesion: 9 N / 5 cm 60°Cwash: 5N/5cm Back riveting: 0.9 N /10 cm The advantage of the process according to the present invention is that under the drying conditions the lower dot already crosslinks and during melting the upper dot crosslinks on account of its terminating with the lower dot, thereby creating an optimum bond. Since after coating the molecular weight of the lower dot is increased strongly, it can no longer sink into the fabric. During the subsequent fixing process, the low-viscosity polyamide of the upper dot is forced to flow against the material to be fixed, since it cannot flow downwards; a very high degree of adhesion is attained thereby with minimal quantities of hot-melt adhesive. The separation layer, previously the weak point of the system, particularly during washing, between upper dot and base dot cannot be attacked so strongly hydrolytically as is the case with previously known systems and it accordingly exhibits substantially higher resistance. Products used: VESTAMELT X 1027-P1 is a ternary copolyamide of Degussa-Huls AG based on LL, CL and DDS/MPD with amino end groups, melting point of 120°C, amino end groups 100 to 400 mVal/kg, preferably 250 to 350 mVal/kg. The trimerized isocyanate is a polyisocyanate with a functionality of 3 to 4, with a melting point of 100 to 115°C. It is a product of Degussa-Huls AG. Example 3: 1500 g Water 35g Mirox TX 40 g Intrasol 12/18/5 400 g VESTAMELT X1316-P1 200 g VESTAMELT X1310-P1 Result: A 5 cm wide strip of this interlining (75 g/m2 cotton) with a CP 66 screen and a coating of 16 g/m2 was fixed to a siliconized blouse material from a cotton/polyester mix at a joint temperature of 155°C for 16 s and a linear pressure of 4 kg/cm2, on a shirt press, after which the composite was subjected to a 60°C wash. Adhesion: 21 N/5 cm 60°Cwash: 19 N/5 cm Test 3a: Comparison to state of the art As in Test 3, 16 g/m2 of a commercially available coating were applied to the same interlining, as per the following formulation: 1500 g Water 35g MiroxTX 40 g Intrasol 12/18/5 600 g VESTAMELT X 250-P1 The following adhesions resulted under the same fixing conditions: Primary adhesion: 16 N / 5 cm 60°C wash: 5 N / 5 cm Result: Hydrolysis resistance is sharply increased by crosslinking (molecular weight increase), something that becomes clearly noticeable in the wash resistances. The strike back inclination is strongly decreased by the gradual molecular weight increase during fixing, effectively increasing adhesion. WE CLAIM: 1. A process for manufacturing a crosslinkable hot-melt adhesive compound for coating and/or laminating surface formations, characterized in that the crosslinking constituent is micro-encapsulated by a silanized polybutadiene and the reactive constituents are first caused to react in the melt by crosslinking. 2. The process for manufacturing a hot-melt adhesive compound as claimed in claim 1, wherein the crosslinking constituent is micro-encapsulated with a silanized polybutadiene in a ratio of 4:1. 3. The process for manufacturing a hot-melt adhesive compound as claimed in either of the preceding claims, wherein the silanized polybutadiene exhibits a silicon 15 content of 2 to 10% by weight, a molar mass of 1500 to 2500 g/mol and a viscosity of 1000 to 3000 mPas. 4. The process for manufacturing a hot-melt adhesive compound as claimed in any one of the preceding claims, wherein crosslinking constituent originates from the isocyanate group and has more than two reactive groups per molecule. 5. The process for manufacturing a hot-melt adhesive compound as claimed in any one of the preceding claims, wherein the isocyanate has a melting range of 110 to 130°C. 6. The process for manufacturing a hot-melt adhesive compound as claimed in any one of the preceding claims, wherein as a crosslinking constituent an isocyanate is micro-encapsulated with a silanized polybutadiene and is caused to react with a second constituent which is a copolyamide or copolyester. 7. The process for manufacturing a hot-melt adhesive compound as claimed in any one of the preceding claims, wherein the second constituent is an amine regulated copolyamide with a melting range of 90 to 150°C and a solution viscosity or relative melting viscosity r|reJ in the range of 1.2 to 1.7. 8. The process for manufacturing a hot-melt adhesive compound as claimed in any one of the preceding claims, wherein the second constituent is an OH group terminated copolyester based on terephthalic acid, isophthalic acid and butane diol or butane diol in combination with small quantities of up to 12 molar % of other diols, having melting points of 100 to 150°C. 9. The process for manufacturing a hot-melt adhesive compound as claimed in any one of the preceding claims, wherein the micro-encapsulated polyisocyanate is dispersed in an aqueous paste and applied by rotary screen printing to a surface formation. 10. The process for manufacturing a hot-melt adhesive compound as claimed in any one of the preceding claims, wherein the reactive mixture is used as a base dot for double dot technology as a strike back barrier. 11. The process for manufacturing a hot-melt adhesive compound as claimed in any one of the preceding claims, wherein the upper dot consists of an amine-regulated copolyamide.

Documents:

0832-mas-2001 abstract-duplicate.pdf

0832-mas-2001 claims-duplicate.pdf

0832-mas-2001 description (complete)-duplicate.pdf

832-mas-2001-abstract.pdf

832-mas-2001-claims.pdf

832-mas-2001-correspondnece-others.pdf

832-mas-2001-correspondnece-po.pdf

832-mas-2001-description(complete).pdf

832-mas-2001-form 1.pdf

832-mas-2001-form 18.pdf

832-mas-2001-form 26.pdf

832-mas-2001-form 3.pdf

832-mas-2001-form 5.pdf