NO135477B - - Google Patents

Description

The invention relates to the use of a copoly-

amide of specific composition as a hot-melt adhesive.

Among other things, you expect a hot-melt adhesive to

its properties, especially the melting ratio and thus its thermal stability, are not significantly changed by environmental influences. A hot melt adhesive contains hydrophilic groups so it swells when stored in water or in a moist atmosphere.

In the case of polyamides whose melting temperature is below approx. l80°C

water absorption leads to a strong reduction in heat resistance so that the bonded parts fall apart when exposed to water, especially hot water.

Polyamide-based hot-melt adhesives which must be resistant to water, especially to hot water, have the least possible content of CONH groups responsible for water absorption. They are produced using as many long-chain dicarboxylic acids as possible, e.g. dimerized fatty acids or

also long-chain amino acids such as oj-aminolauric acid,

respectively their lactam. The relatively small content of these polyamides of CONH groups does not allow a high water absorption.

In many cases, however, it is desired

the highest possible water absorption. This applies, for example, to for certain hot-melt adhesives, especially for those that are to be used for gluing together textiles and are not to influence the moisture balance between the skin and the surrounding air. Also for glued together wooden parts, this property is often important for compliance with the breathing activity. The provision of such an adhesive on a polyamide basis was the task that formed the basis of the invention.

Copolyamides with a large amount of similar unbranched structural units are partially crystalline and often have melting temperatures well above 200°C. Such high melting temperatures are usually undesirable for various reasons when used as hot melt adhesives. With small contents of the aforementioned similarly unbranched structural units, the melting temperature drops considerably. At the same time, however, the resistance to water, especially to hot water, also decreases, so that in order to avoid this disadvantage, one is forced to use as many long-chain dicarboxylic acids, diamines and aminocarboxylic acids as possible. Of course, however, such polyamides only have a very small ability to absorb moisture.

It has now been found that certain polyamides based on branched diamines as hot-melt adhesives meet the requirements for high water absorption and at the same time resistance to hot water, although their melting temperatures are below 160°C.

The invention thus relates to the use of a copolyamide of-1) 10 - 90 mol? aliphatic and/or cycloaliphatic dicarboxylic acid with 4-12 C atoms and to these equivalent amounts of aliphatic and/or cycloaliphatic diamines with 2-15 C atoms, at least half of the diamine part being branched,

i.e. that it has alkyl groups attached to the C atoms of the main chain or ring, and

2) 90 - 10 mol% residues of w-aminocarboxylic acids

with H - 12 C atoms and/or corresponding lactams such as hot-melt adhesives.

In order to obtain hot-melt adhesives with melting temperatures below 150°C and with a resistance to washing lye of 80°C, in the components mentioned under point 1) of the polyamide to be used, at least half of the diamine residues must contain at least 2 bonded to the carbon atom of the main chain or ring alkyl groups-.

The melting temperature is not lower when open-chain diamines are combined with cyclic diamines. This surprisingly does not affect the resistance to hot water. Particularly favorable are open-chain diamines with at least three alkyl groups bound to carbon and cyclic diamines with at least three alkyl groups bound to the ring carbon atoms in part 1). This achieves melting temperatures below 150°C and resistance to boiling washing lye.

A moisture absorption capacity of 8 - 12% is achieved with hot melt adhesives of the following composition: 1. 10-40 mol? residues of aliphatic, open-chain and/or cyclic dicarboxylic acids with 4-12 C atoms and to these equivalent residues of aliphatic, open-chain and/or cyclic diamines with 2-15 C atoms, at least half of the diamine residues being branched, and

2. 10 - 40 moles? residues of ui-aminocaproic acid

25 - 80 moles? residues of co-aminocarboxylic acids with

7-12 C atoms.

Despite relatively high melting temperatures, these hot melt adhesives can be processed at temperatures down to 110°C as they have a wide softening range.

A particularly high water absorption capacity of up to approx. 15? is achievable with hot melt adhesives of the following composition: 1. 10 - 40 mol? aliphatic, open-chain and/or cyclic dicarboxylic acids with 4-12 carbon atoms and to these equivalent residues of aliphatic, open-chain and/or cyclic diamines, with 2-15 C atoms, with at least half of the diamine residues being branched, and

2. 90 - 60 moles? residues of 10-aminocaproic acid.

This particularly interesting hot-melt adhesive has melting temperatures as low as 110°C and, despite its high water absorption, is resistant to washing lye up to 80°C, in the event of a high content of aminocaproic acid residues of 85 - 70 mol? also resistant to boiling washing lye. The residues of the following dicarboxylic acids can be contained in the hot melt adhesives according to the invention: Open-chain and cyclic, branched and unbranched aliphatic dicarboxylic acids with 4-12 C atoms, resp. succinic acid, adipic acid, 2,2,4-trimethyladipic acid, azelaic acid, dodecanoic acid, cyclohexane-1,4-dicarboxylic acid.

The residues of the following diamines may be contained

in the hot melt adhesives according to the invention:

Up to 50 moles? of the diamine moiety of open-chain or cyclic aliphatic unbranched diamines with 2 - 12 C atoms, e.g. ethylenediamine, hexamethylenediamine, dodecamethylenediamine, 50 - 100 mol? of the diamine part of branched diamines with 3-15 C atoms, e.g. 1,2--propylenediamine, 3-methylhexamethylenediamine, 3,3-dimethylhexamethylenediamine, 2,4,4- and 2,2,4- trimethylhexamethylenediamine, 3j6-diamino-2-methylcyclohexane, l-amino-3-aminomethyl 1-3-,5,5-trimethylcyclohexane,. 4,4*-bisamino-methyl-2,2'-dimethyldicyclohexylmethane. The residues of the following α-aminocarboxylic acids can be contained in the hot melt adhesives according to the invention: two-aminocarboxylic acids with 4-12 C atoms, e.g. oj-aminobutanoic acid, io-aminocaproic acid, co-aminoundecanoic acid, . co-aminolauric acid. ;Addition of additional polyamide formers to achieve specific properties is possible. Thus allows e.g. by adding small amounts of aromatic dicarboxylic acids or diamines, the melting temperature increases if necessary. ;The average molecular weights of the polyamides used according to the invention as hot-melt adhesives are between 2000 and 40000. The polyamides best suited for textile bonding have average molecular weights between 6000 and 25000. ;The polyamides used according to the invention can be very easily produced according to known methods, e.g. by melt condensation. The molecular weights are adjusted in a known manner by using an excess of diamine or dicarboxylic acid or by adding monofunctional amines or carboxylic acids by the condensation. The indication of the mole percentages refers to the CONH groups, i.e. the sum of 0.5 mol dicarboxylic acid residues and 0.5 mol diamine residues treated as 1 mol. The mole percentages are calculated in the following way: x mol? aminocarboxylic acid; or 1actamer ;;dicarboxylic acid (+equivalent amount of diamine). The melting temperature is determined with a hot table microscope. At the specified temperatures, the samples begin to stick to the substrate. ;Example 1. ;A copolyamide of ;1.05 mol adipic acid ;0.70 mol 1-amino-3"-aminomethyl-3,5,5-trimethyl-cyclohexane ;0.30 mol 2,2,4-trimethylhexamethylenediamine 6 ,00 mol of caprolactam is produced by melt condensation at 200 - 230°C. The average molecular weight is about 15,000. The melting temperature is at 130°C. The copolyamide absorbs a maximum of about 12% water. The product is crushed in a blow mill. to a grain size of 0.1 to 0.44 mm. To test the adhesive strength, the powder is sprinkled in thin, even layers on 4 x 10 cm pieces of linen fabric and covered with pieces of the same size of the same fabric. By pressing briefly with an iron at At 130°C, the two layers of fabric are glued together. After half an hour of heating and stirring this test piece in water of 95 - 100°C containing 0.4% of a household detergent, no reduction in adhesion is determined. Similarly, half hour's stirring in trichloroethylene at 6.0°C without affecting the adhesive strength. ;Example 2. ;A copolyamide of ;1.04 mol azelaic acid ;0.30 mol 1,3"-bisaminomethylcyclohexane 0.30 mol 2-methylhexamethylenediamine 0.40 mol 3,3-dimethylhexamethylenediamine 5.20 mol caprolactam; produced by melt condensation at 200 - 230°C. The average molecular weight is 12,000. The melting temperature is 140°C, the water absorption 11?. A 0.2 mm thick foil of this material is placed between two thin wooden boards which are pressed in a steam heated. press. with a pressure of 10 kg/cm 2. The glued wooden parts are stored for 10 hours in water of 60<G>C. The adhesion does not loosen. ;Example 3. ;By replacing 1,3-bisaminomethylcyclohexane in example 2 with hexamethylenediamine, a polyamide is obtained whose melting and processing temperature is around 10°C higher. The heat resistance also increases by 10°C. ;Example 4. ;A copolyamide of ;1.08 mol adipic acid ;0.60 mol 2,4,4-trimethylhexamethylenediamine 0.40 mol 1-amino-3-aminomethyl-3,5j5-cyclohexane 7.00 mol caprolactam ;is prepared by melt condensation at 200 - 230°C. The average molecular weight is 10,000. The melting temperature is 130°C, the maximum water absorption 12?. The copolyamide can be used for gluing together lining materials in upholstery pieces. The bonded parts do not loosen in boiling washing lye.. ;Example 5» ;A copolyamide of ;1.06 mol ^adipic acid ;0.60 mol 1-amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane ;0, 20 mol dodecanemethylenediamine; 0.20 mol 2,4,4-trimethylhexamethylenediamine 2.00 mol caprolactam; 4.00 mol w-aminoundecanoic acid; produced by melt condensation at 200 - 230°C. The average molecular weight is 17,000. The melting temperature is 140°C, the maximum water absorption 8?. The copolymer is dissolved in ethanol and sprayed onto a sheet of cellulose fibres. After a short pressing at 150°C, a solid flour material is obtained which, when washed with washing lye at 80°C, retains its firmness. ;Example 6. ;Et.copolyamide of ;0.70 mol adipic acid ;0.30 mol azelaic acid ;1.08 mol 1-amino-3-aminomethyl-3)5,5-trim'ethyl-•'<*>. '. cyclohexane

1.00 mol caprolactam 5.00 mol w-aminoundecanoic acid

is produced by melt condensation at 200 - 230°C. The average molecular weight is 14,000. The melting temperature is 150°C, the maximum water absorption 12?. Staple fibers are produced from this polyamide and these are added during the production of a fleur of nylon 6.6 to a weight amount of 5%. When pressing at 120°C, the fleece is fixed. When washing in lye at 100°C, no loss of firmness was observed.

Example 7-

Of

1.04 mol of sebacic acid,

0.50 mol of hexamethylenediamine,

0.25 mol 1:1 isomer mixture of 2,2,4- and 2,4,4-trimethyl-hexamethylenediaminej

0.25 mol of 3-aminomethyl-3,5,5-trimethyl-cyclohexyl-amine,

0.20 mol ε-caprolactam

is produced by melt condensation at 200 - 240°C a polyamide, whose average molecular weight was approx. 10,000. The melting temperature was approx. l40°C. The maximum water intake was determined to be approx. 11?.

The polyamide was applied as a hot-melt adhesive in the manner described in example 1, the pressing temperature being 140°C. No influence on the firmness could be determined by the washing process mentioned in example 1.

Example 8.

Of

1.03 mol dodecanedicarboxylic acid,

0.50 mol 1:1 isomer mixture of 2,2,4- and 2,4,4-trimethyl-hexamethylenediamine,

0.50 mol 3-aminomethyl-3,5,5-trimethyl-cyclohexyl-amine,.

0.50 mol w-laurin lactam,

a polyamide whose average molecular weight was approx. 12,000. The melting temperature was approx. 135°C. The maximum water intake was determined to be approx. 12?.

Claims (6)

1. Use of a copolyamide of 1) 10 - 90 moles? aliphatic and/or cycloaliphatic dicarboxylic acid with 4 - 12 C atoms and to these equivalent amounts of aliphatic and/or cycloaliphatic diamines with 2 - 15 C atoms, with at least half of the diamine part being branched, i.e. that it has alkyl groups bound to the main chain or the C atoms of the ring, and 2) 90 - 10 moles? residues of co-aminocarboxylic acids with 4-12 C atoms and/or corresponding lactams as hot-melt adhesives. 2. Use according to claim 1, where in the copolyamide's component 1) at least half of the diamine residues contain at least 2 alkyl groups bound to carbon atoms in the main chain or ring. 3. Use according to claims 1 and 2, where in the copolyamide's component 1) at least half of the diamine residues contain at least three alkyl groups bound to carbon atoms in the main chain or ring. 4. Use according to claims 1 - 3, where the copolyamide's component 1) contains open-chain and cyclic diamine residues in a molar ratio of 80:20 to 20:80. 5» Use according to claim 1 of a copolyamide as a hot-melt adhesive, where the copolyamide is composed in the following way: 1. 10 - 40 mol? residues of aliphatic, open-chain and/or cyclic dicarboxylic acids with 4 - 12 C atoms and to these equivalent residues of aliphatic, open-chain and/or cyclic diamines with 2-15 C atoms, with at least half of the diamine residues being branched, and 2. 10-40 moles? residues of w-aminocaproic acid and 25 - 80 mol? residues of cj-aminocarboxylic acids with 7 - 12 C atoms. 6. Use of a copolyamide according to claims 1-5, Bom hot melt adhesives, where the copolyamide has the following composition: 1. 10 - 40 mol? residues of aliphatic, open-chain and/or cyclic dicarboxylic acids with 4-12 C atoms and to these equivalent residues of aliphatic, open-chain and/or cyclic diamines with 2-15 C atoms, with at least half of the diamine residues being branched and 2. 90 - 60 moles? residues of two-aminocaproic acid.