EP3864200A1

EP3864200A1 - Melt-drawn polyamide filaments

Info

Publication number: EP3864200A1
Application number: EP19783050.8A
Authority: EP
Inventors: Lan DE GANS LI; Martin Wielpütz; Markus Hartmann; Dirk Heinrich BÜCKER
Original assignee: Evonik Operations GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2018-10-10
Filing date: 2019-10-09
Publication date: 2021-08-18
Also published as: CA3115386A1; CN112955588A; JP2022503967A; US20210381135A1; WO2020074572A1; CN112955588B; MX2021004065A; BR112021006566A2; AR116725A1; KR20210069705A; JP7446289B2; EP3636808A1

Abstract

The invention relates to drawn filaments based on linear, branched or cyclic aliphatic or partially aromatic polyamides, wherein the filaments have been drawn at a temperature between the glass transition temperature and the melting point and wherein the filaments are cooled to room temperature under full tensile load.

Description

Melt-hidden polvamide filaments

The present invention is directed to drawn filaments based on linear, branched or cyclic aliphatic or partially aromatic polyamides, the filaments having been drawn at a temperature between the glass transition temperature and the melting point and the filaments being cooled to room temperature under full tensile load.

Fiber-reinforced materials are mostly based on the use of glass or carbon fibers in polymers. There is therefore basically the problem of the compatibility of the fibers with the matrix material and thus the problems of bonding between the reinforcing material and the matrix. This is often a particular problem when using thermoplastics as a matrix. Furthermore, these materials are not recyclable because the separation of the fibers is very expensive.

In the prior art, two processes for stretching polyolefins, such as polyethylene or polypropylene, are known, the melt spinning process (WO 2004/028803 A1) and the gel spinning process (WO 2010/057982 A1). Polyolefins can easily be stretched at room temperature, the stretching speed having to be chosen relatively low due to the exothermic nature of the stretching. The stretched polyolefins have the disadvantage that they shrink very much after stretching when processed at elevated temperatures and therefore first have to be equilibrated at the desired working temperature. Furthermore, stretched polyolefins have very limited mechanical values which limit their use as reinforcing fibers. In particular, the lack of thermal stability and the lack of pressure resistance (cold formability) are disadvantageous.

DE 766441 and GB 598820 claim an improvement in the mechanical values of stretched polyamide wires by targeted shrinkage, for example with the aid of water or water vapor. For the purposes of the present invention, however, shrinkage processes are disadvantageous. In particular, the disadvantageous effect of water in relation to the tensile strength is evident.

WO 2013/190149 A1 discloses ductile fibers of various thermoplastics, preferably polypropylene and polyethylene, as a component of so-called PrePregs. This includes interweaving of thermoplastic fibers with brittle fibers, in particular carbon fibers.

These materials are then preferably deep-drawn or pressed in a matrix made of the material of the ductile fibers. The ductile fiber melts and improves the bond between the matrix and the brittle fiber.

The production of fully aromatic polyamide fibers, such as poly (p-phenylene terephthalamide) (PPTA, aramid under the brand names: Kevlar® (trademark of DuPont, USA), Twaron® (trademark of Teijin Lim, Japan) are described in US 3,869,430 A. These Fibers are made from a sulfuric acid solution using the so-called wet spinning process, which is expensive, technically difficult and environmentally hazardous.

In WO 2015/107024 A1, partially aromatic polyamides are stretched with a stretching factor of less than 5; the stretching temperatures are preferably just as high as possible Glass transition temperature. Any shrinkage can be counteracted by heating the stretched filaments as high as possible under tensile load, this temperature being above the stretching temperature. So the filaments have to be heated twice.

No. 3,393,252 discloses mixtures of two non-isomorphic polyamides whose glass transition points must be below 120 ° C. and above 140 ° C., which are used to stabilize tires.

In US 5,01,645, fibers are made by a process in which the tow rope is first drawn between multiple feed and draw rolls, followed by heating and cooling the draw filaments to anneal them under controlled tension.

In the context of this invention, the term filament means fibers, films or tapes. Preferred filaments are films or tapes. Films in particular are preferably stretched in more than one direction. The filaments preferably have an aspect ratio of greater than 2, more preferably greater than 10, more preferably greater than 50 and particularly preferably greater than 100. The aspect ratio is defined as the ratio of width to thickness, the length being more than 5 times, preferably more than 10 times, more preferably more than 100 times and in particular more than 1000 times the width. So-called continuous filaments, which e.g. have a length of 10 meters and more.

The object of the present invention was therefore to produce drawn filaments from aliphatic or partially aromatic thermoplastics, and to make them harmless, simple and

to provide a solvent-free process for stretching polyamide.

The task was solved by stretched filaments made of polyamide, the filaments being cooled under full tensile load after stretching.

The present invention relates to drawn filaments containing at least 80% by weight, preferably 85% by weight, more preferably 90% by weight, more preferably 95% by weight and in particular consisting of linear, branched or cyclic aliphatic or partially aromatic Polyamides,

the dry filaments were drawn at a temperature between

Glass transition temperature and melting point and

whereby the filaments are cooled dry to below 100 ° C under full tensile load.

Another object of the invention is a method for producing the drawn filaments according to the invention. Another object of the invention is the use of the drawn filaments according to the invention for the production of composites.

Another object of the invention is the use of the drawn filaments according to the invention for the production of winding layers.

An advantage of the drawn filaments according to the invention is that they shrink little at elevated temperature, that is to say they have hardly any relaxation effect.

It is also advantageous that the drawn filaments according to the invention have high mechanical stability. The mechanical stability is preferably measured in the form of a tensile strength at break in the direction of stretching. In addition, the maximum stress before breaking (max strength) can be measured.

It is also advantageous that the drawn filaments according to the invention have high mechanical stability even at elevated temperature.

The drawn filaments according to the invention, the composites according to the invention containing the filaments according to the invention and the production and use according to the invention are described below by way of example, without the invention being exemplary thereof

Embodiments should be limited. If areas, general formulas or classes of compounds are given below, these should not only refer to the corresponding areas or

Include groups of connections that are explicitly listed, but also all sub-areas and sub-groups of connections that can be obtained by removing individual values (areas) or connections. If documents are cited in the context of the present description, their content should completely belong to the disclosure content of the present invention. If percentages are given below, they are percentages by weight unless otherwise stated. For compositions, the% data relate to the total composition, unless stated otherwise. If mean values are given below, they are mass averages (weight average) unless otherwise stated. If measurement values are given below, these measurement values were determined at a pressure of 101325 Pa and a temperature of 25 ° C, unless otherwise stated.

The scope of protection includes customary packaging and packaging of the products according to the invention as such, as well as in possible forms of comminution insofar as these are not defined in the claims.

The polyamides can be produced from a combination of diamine and dicarboxylic acid, from a co-aminocarboxylic acid and / or the corresponding lactam. Here, the co-aminocarboxylic acid or the lactam or a mixture of various such monomers an arithmetic mean preferably at least 7.0 carbon atoms. In the case of a combination of diamine and dicarboxylic acid, the arithmetic mean of the C atoms of diamine and dicarboxylic acid is preferably at least 7.0. Suitable polymers according to the invention are PA 6.9 (which can be prepared from hexamethylenediamine [6 C atoms] and nonanedioic acid [9 C atoms]; the average of the C atoms in the monomer units here is 7.5), PA 6.8, PA 6.10, PA 6.12 , PA 6.13, PA 6.14, PA 6.18, PA 10.6, PA 10.10, PA 10.12, PA 12.12, PA 10.13, PA 10.14, PA 1 1, PA 12, PA 6.T, PA 9.T, PA 10.T, PA 12.T, PA 14.T, PA P ACM.10 (PACM = 4,4'-diaminocyclohexylmethane), PA PACM.12, PA MACM.10 (MACM = 3,3'-dimethyl-4,4'- diaminocyclohexylmethane), PA MACM.12, PA TMD.10 (TMD = 1, 6-diamino-2,4,4-trimethylhexane, 1, 6-diamino-2,2,4-trimethylhexane), PA TMD.12 and in general Polyamides derived from a diamine and nonadecanedioic acid. Copolyamides are also suitable; the building blocks mentioned diamine and dicarboxylic acid, w-aminocarboxylic acid and lactam can be combined as desired. In addition, polyetheramides based on these polyamides and polyetheresteramides are also suitable according to the invention. Polyetheramides are made from dicarboxylic acid-regulated polyamide blocks and

Polyether diamine blocks built up, polyether ester amides accordingly

dicarboxylic acid regulated polyamide blocks and polyether diol blocks. The polyether units generally contain 2 to 4 carbon atoms per ether oxygen. Polyether amides and

Polyetheresteramides are known to the person skilled in the art and are commercially available in a large number of types.

The polyamides preferably contain a maximum of 40 and particularly preferably a maximum of 26 carbon atoms in the monomer units in the arithmetic mean.

The polyamides preferably contain no solvents.

The term "dry" means that the filaments are not brought into contact with a liquid, especially not with water. The filaments therefore preferably have a maximum of 1.5% by weight of water, more preferably a maximum of 1% by weight, in particular a maximum of 0.9% by weight. The water content is determined by customary methods of the prior art, preferably by Karl Fischer with a coulometer. For example, the KF Coulometer 831 from Metrohm is suitable; a suitable oven temperature is 170 ° C.

The minimum stretching temperature Trec _k, min is preferred using equation (1):

determined, where T _m = melting point, T _g = glass transition temperature and Xc are the crystallinity, and

the crystallinity being determined using equation (2)

The sizes T _m , T _g and AH _m are determined within the scope of the present invention with the aid of the DSC, preferably determined according to EN ISO 11357-1: 2016D, more preferably as described in the examples.

The values AH _m ° for calculating the crystallinity Xc are taken from standard tables, e.g. B. van Krevelen “Properties of Polymers”, 4th edition, 2009. The following are preferred Accepted values:

Polyamide AHm ° Tg Tm

PA 6 230 40 260

PA 1 1 226 46 220

PA 12 210 37 179

PA 6.6 300 50 280

PA 6.10 260 50 233

PA 6.12 215 54 200

PA 10.9 250 214

PA 10.10 200 60 216

The values refer to the polyamide of the unstretched filaments, in the 2nd heating in the DSC.

With a crystallinity of 0 and close to 0, the stretching temperature is at least 5 ° C above the glass transition temperature. With a crystallinity of 1 and close to 1, the stretching temperature is at least 5 ° C below the melting temperature.

The filaments according to the invention are preferably drawn at a temperature above the minimum drawing temperature Trec, min, more preferably at a drawing temperature defined according to

Equation (G3)

where Y is from 0.05 to 0.95, preferably 0.1 to 0.8, more preferably 0.2 to 0.7, particularly preferably 0.3 to 0.6.

The filaments according to the invention are preferably drawn by an elongation factor RF greater than or equal to 2.5, more preferably greater than or equal to 5, more preferably RF greater than or equal to 10, particularly preferably greater than or equal to 15 or greater.

The filaments according to the invention have preferably been drawn in free space without contact. The zone in which the stretching takes place is a zone in which the atmosphere of the

Environment is heated, e.g. B. a kind of furnace, tube furnace or the space between two heated plates.

The filaments of the invention can be drawn continuously or in batches.

Static stretching, ie stretching, in which one end of the filament remains at rest at speeds of 10 mm / min to 200 mm / min, preferably from 20 mm / min to 100 mm / min, more preferably 30 mm / min to, is preferred Stretched 80 mm / min.

Preferred continuous stretching is carried out so that the low

Transport speed preferably in the range from 5 mm / min to 20,000 mm / min, preferably from 10 mm / min to 3,000 mm / min, more preferably from 50 mm / min to 2500 mm / min, more preferably 100 mm / min to 2000 mm / min, more preferably 500 mm / min to 1500 mm / min. The speed of the faster running transport unit is calculated using the stretching factors.

The filaments according to the invention can be drawn by only one drawing operation or by several successive ones. In the latter case, the stretching temperature must be selected higher. Only one stretching process is more preferred.

The filaments according to the invention are cooled to below 100 ° C. after stretching. This cooling is preferably slow, preferably at least 1 second, more preferably at least 5 seconds, more preferably at least 10 seconds, particularly preferably at least 30 seconds, particularly preferably at least 1 minute.

Water cooling of the drawn filaments is excluded. The drawn filaments are preferably not exposed to water in any state of aggregation, steam is hereby expressly excluded, also the deviation from standard conditions, in particular the use of different pressures to generate different states of aggregation of water is excluded.

The stretched filaments according to the invention preferably have one when heated

Temperature below the melting point only a small shrinkage / relaxation in

Train direction on.

The relaxation temperature is preferably above the glass transition temperature and below the melting temperature, preferably below the stretching temperature.

The filaments according to the invention preferably relax at most 6% with respect to the stretched length, preferably at most 5.5%, more preferably at most 5%, further more preferably at most 4.5% and particularly preferably at most 4%.

The filaments according to the invention more preferably relax at a relaxation temperature of 80 ° C. at most 6% in relation to the stretched length, preferably at most 5.5%, more preferably at most 5%, further more preferably at most 4.5% and particularly preferably at most 4% .

The filaments according to the invention are preferably not relaxed under tensile stress.

The drawn filaments according to the invention preferably have a length which is greater than 5 times a dimension at right angles to the length; the filaments are preferably so-called endless filaments. The length of the filaments is always determined in the pulling direction.

In the context of this invention, the term filament means fibers, films or tapes. Films in particular are preferably stretched in more than one direction.

The individual filaments can be made into bundles like filament bundles; preferred bundles of fibers are fiber bundles and yarns. The filament bundles, including fiber bundles or yarns, can be processed into further composites, preferably into unidirectional or multi-directional fabrics, interweaving such as mats, and entanglements, or also mixed forms. Layers can consist of filaments cut to a certain length, as well as of endless filaments in the form of windings around pipes, for example.

Preferred fabrics made of endless filaments are wrapping layers around hollow bodies. They are preferably unidirectional or multidirectional. Multi-directional winding layers have an angle with respect to the direction of pull of the filaments. This angle is preferably in the range from 5 to 120 °, more preferably from 30 to 90 °, particularly preferably 15 to 80 °. In the case of winding layers around pipes, these winding layers have a pitch angle with respect to the pipe center. Different winding layers preferably have different pitch angles. The winding layers around tubes are preferably designed with respect to the pitch angle in such a way that after one revolution the edges of the layer connect flush with one another.

Brief description of the pictures:

Fig 1: graphical representation of the results according to Table 1;

left group stretch factor 1, 1 (P 1, 1); right group RF = 2.5 (P 1, 2);

bold hatching: relaxation temperature 80 ° C, thin hatching: relaxation temperature

120 ° C;

Hatching vertical represents the shrinkage in the direction of stretching and cross-hatching represents the extent at right angles to the direction of stretching

Fig. 2: Plotting the max strength, o _m [MPa] over temperature at which o _{m was} determined, determinations for samples with different stretching factors RF]

Examples

Materials PA 6.10: VESTAMID Terra HS 16 (Evonik)

PA 10.10: VESTAMID Terra DS 18 (Evonik)

PA 12: VESTAMID L2101 nf (Evonik)

Trogamid: CX7323 (Evonik)

PA 11

Methods

DSC:

Perkin bucket, type Diamond, automatic peak detection and integration, based on DIN EN ISO 1 1357-1: 2010, heating rate 20 K / min.

Example 1, production of the test pieces:

The above-mentioned polyamides were made into a tape with a thickness of 150, 350 and Extruded 650 pm, cooled to 30-40 ° C.

The tapes were calendered at a speed of 1.4 m / min, the width was 35 mm.

P 1, ^* are samples from PA 12;

P 2 are samples made of trogamide;

P 3, * are samples from PA 6.10;

P 4, * are samples from PA 10.10;

P 5, * are samples from PA 11.

Example 2, stretching the specimens:

Method 1:

In a tractor (Zwick, Z101-K) test pieces according to Example 1 were with a

Speed of 50 mm / min stretched at 140 ° C. Before the strain relief, the

Sample pieces cooled to room temperature. The cooling was carried out slowly within 2 minutes or quickly within 10 seconds. Further samples according to the following table.

P 1.0 P 1.3 P 2.0 P 2.1 P 3.0 P 3.1 P 5.0 P 5.1

Stretching factor 1 5 1 4.5 1 4.6 1 4.6

Stretching speed

50 50 25 25

[mm / min]

Stretching temperature [° C] 140 60 80 60 cooling [min] 2 2 2 2

Method 2:

An endless test piece according to Example 1 was provided on a spool, on a continuously working machine (retech drawing) at one

Material feed speed of 1 to 2.5 rpm and a pulling speed of up to 32 rpm stretched to a stretching factor (RF) of 3.5 to 8. The stretching took place at a temperature of 60 to 140 ° C.

Example 0: Continuous stretching process - samples P 1, * (PA12), thickness 650pm, width 10mm.

Example 3, Relaxations:

Test pieces of Example 2 were cut to a length of 10 cm. The test pieces according to Example 2, Method 1 were cut at both ends. The specimens were stored in a thermal cabinet without tensile load, individually horizontally and freely movable, at temperatures of 80 ° C and 120 ° C for 5 h.

After cooling, the samples were measured in their two flat dimensions. The results are shown in Table 1 and Figure 1.

Table 1, relative change in the dimensions of the test pieces according to Example 3, length = in the direction of pull, width = 90 ° to the direction of pull Sample length width length width

80 ° C 120 ° C

P 1, 1; RF = 1.1 -4.03 +1.23 -11.96 +2.38

P 1, 2; RF = 2.5 -2.67 +0.61 -4.17 +1.39

Polyamide samples show little relaxation and surprisingly show increasing relaxation with increasing stretching factor.

Example 4 mechanical tests:

Tensile tests

Shoulder rods according to DIN 527-5: 1997 (A rod) were punched out of the stretched ribbons, the thickness resulted from the stretching test and was not changed.

The tensile strength was measured on 3 test specimens in each case using a tensile tester from Zwick at different temperatures. Test speed = 5 mm / min, clamping length = 120 mm and measuring length of the incremental transducer = 75 mm.

Temperature 23 ° C, relative humidity 50%.

The results are shown in Tables 2 and 3 and Figure 2.

The results represent the arithmetic mean of 3 test pieces.

Table 2: T = 23 ° C, results of the tensile tests according to Example 4.

P 1.0 P 1.3 P 2.0 P 2.1 P 3.0 P 3.1 P 5.0 P5.1

Stretching factor 1 5 1 4.5 1 4.6 1 4.6

_{Modulus of} elasticity [MPa] 982 3277 1572 3049 686 2189 873 1984 max strength, o _{m 7fi}

332 56 207 49.2 182.9 56.3 174.1

[MPa] ^ö

max strain, c _m [%] 189 9.1 88 1 1, 8 233.5 23.6 267.7 46.0 strength at break, Ob _{7 "}

332 55 207 49.2 182.4 56.3 174.1

[MPa] ⁶

strain at break, 8b [%] 181 9.12 102 12 234.2 23.9 267.7 46.0 Table 3: T = 23 ° C, results of tensile tests according to Example 0

Table 4: max strength, o _m [MPa] for different test temperatures, results of tensile tests according to Example 4, for samples with different stretching factors

P 1, 0 P 1, 1 P 1, 2 P 1, 4

Stretching factor 1 1, 1 2.5 4.7

Test temperature [° C] o _m [MPa] o _m [MPa] Om [MPa] o _m [MPa]

23 76 135 223 294

40 77.6 118 209 288

60 70 113 195 270

80 67.7 102 147 222

Claims

1. drawn filaments containing at least 80% by weight of linear, branched or cyclic aliphatic or partially aromatic polyamides,

the dry filaments were drawn at a temperature between

Glass transition temperature and melting point and

the filaments are cooled dry to below 100 ° C. under full tensile load, water being excluded for cooling.

2. Drawn filaments according to claim 1, wherein the minimum stretching temperature T _{reck, min} with the help

Equation (1):

the crystallinity being determined using equation (2)

whereby the sizes Tm, T _g and AH _{m are determined} by DSC according to EN ISO 1 1357-1: 2016D and AH _m ° standard tables are taken.

3. Drawn filaments according to one of the preceding claims, wherein the when heated to a temperature above the glass transition temperature and below the

Melting point, preferably below the stretching temperature, only a low one

Have shrinkage / relaxation in the pulling direction of maximum 6% with respect to the stretched length.

4. Drawn filaments according to one of the preceding claims, wherein the monomers of the polyamides aminocarboxylic acid or the lactam or a mixture of different such monomers in the arithmetic mean preferably at least 7.0 carbon atoms, in a combination of diamine and dicarboxylic acid is the arithmetic Average of the C atoms of diamine and dicarboxylic acid preferably at least 7.0.

5. A method for producing the drawn filaments according to any one of claims 1 to 4, wherein the filaments have been drawn at least by a factor of 2.5.

6. Use of the drawn filaments according to one of claims 1 to 5 for the production of

Ally.

7. Use of the drawn filaments according to one of claims 1 to 5 for the production of winding layers.