DE1231391B - Process for the treatment of oriented synthetic polyester threads or fibers - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

D06m

German class: 29 b-5/04

Number:
File number:
Registration date:
Display day:

1 231391
J20599IVc / 29b
September 29, 1961
December 29, 1966

Textiles that contain staple fibers made of polyesters, such as polyethylene terephthalate, contain, easily form small balls or nodules of fibers on their surface when used. The propensity for education Such balls of fibers in use are known as pilling and are believed to be associated with the Migration of polyester fibers not firmly held in place in the yarn or fabric. Such a pilling effect therefore occurs with low-twist yarns made from polyester fibers and loosely woven or knitted fabrics containing such yarns.

The method according to the invention relates to the treatment of oriented synthetic polyester threads or fibers with a chemical agent such that the filaments or fibers are locally weakened are, the novelty of the invention is that the treatment of the threads or fibers with the chemical agents before processing into textiles and before heat setting, but after the ao Crimping takes place, the crimp being produced in that the threads are bent sharply and thereby the inner curvature of the threads is given a compressive stress that is beyond the Elasticity limit is, which is reached when the pressure is applied by bending.

According to the invention, cables are to be made from polyester threads, which after a as Cable-to-sliver conversion known stretch breaking process be converted into tops in which the forces necessary to break the threads into fibers are lower and the breaking is relieved. Excess lengths during cutting are switched off.

Furthermore, a method for producing such threads and fibers is proposed, with crimped synthetic polyester filaments or fibers treated with a chemical agent under such conditions be that the threads or fibers at intervals corresponding to the vertices of their Ripples are weakened. The method is preferably applied to threads in the form of a crimped stretched cable was applied before the filaments were subjected to a heat setting process to fix the imparted crimp and before cutting or breaking into staple fibers.

Numerous chemical agents can be used. The most expedient are alkaline solutions, such as sodium hydroxide solution, ammonia, and also solutions of certain quaternary ammonium salts or methyl alcohol, which can be added to the sodium hydroxide solution, or certain diamines, such as a solution from processes for the treatment of oriented
synthetic polyester threads or fibers

Applicant:

Imperial Chemical Industries Limited, London

Representative:

Dr.-Ing. H. Fincke, Dipl.-Ing. H. Bohr
and Dipl.-Ing. S. Staeger, patent attorneys,
Munich 5, Müllerstr. 31

Named as inventor:

Geoffrey Leonard Goulding,

Keith Philip Barr, Harrogate, Yorkshire

(Great Britain)

Claimed priority:

Great Britain September 30, 1960 (33 612)

Hexamethylenediamine, anhydrous glycols, including high molecular weight glycols, as well as their Esters and ethers, which are still liquid at room temperature. These solutions can optionally inert diluents are added.

A treatment for uncrimped threads or crimped but heat set threads under the the same conditions does not lead to the same weakening at certain distances along the Threads or fibers, as the chemical agents attack more evenly. It should be noted that the Weakening or breaking of the threads or fibers as a result of the treatment according to the invention is a direct one Follow the selective intensity of attack by the agents at intervals along the filaments or fibers is at the vertices of the crimps, while the sections between the vertices are at the uniform application of the chemical agent to a lesser degree or practically none at all to be attacked. As a result, the parts of the threads treated with a suitable agent break or fibers under mechanical stress, preferably at intervals, while those in between Parts remain practically unaffected.

It is believed that the selective weakening at the peaks of the crimp is due to internal Tension is caused, which arise from the sharp deformation during the crimping and

6OT 74W391

cause local disorientation in the threads or fibers. For this reason, stuffer box pucker and gear crimps are preferred.

The treatment conditions are to be chosen so that in the uncrimped part of the threads or Fibers while no intolerable weakening occurs the peaks of the crimps by at least one third, or preferably about one half or more weakened in comparison with their original strength. That can be achieved by measuring the strength of a small sample of the threads or fibers before and after the treatment measures and examines the broken ends of the fibers, which only at the apexes of their Ripples should occur.

The stresses applied during the crimping should preferably be such that they allow the bending of the Fibers at certain intervals cause and permanent deformation with compression beyond the elastic limit at the inner curvature of the bent thread and one Tensile stress on the outer curve of the bent thread to produce a deformation not more than 5% of the elastic limit, and only at intervals along the thread axis. at Polyester threads with a practically circular cross-section should preferably be deformed in a spaced bend of the threads with a radius of curvature of less than 50 times the Thread diameter exist, d. i.e., a 4 denier thread should have a radius of curvature less than Can be bent 0.02 cm. The crimping conditions should preferably be set up so that the Gaps between crimps give 5 to 18 crimps per inch (2.54 cm). At a Curl frequencies below 5 can cause curled fibers migrating to the surface of the fabric cause the fibers to break off at intervals that are too great to prevent pilling. In other words, the protruding broken fiber ends are too long for the nodules to form to prevent. On the other hand, if the crimp frequency is over 18 crimps per As inches increase, the usable fiber lengths between the crimp apices can increase be short, and textiles made from such fibers are likely to exhibit reduced wear and tear Wear resistance and will therefore hardly find any technical use.

To explain the above requirements, reference is made to the drawing, which shows a schematic plan view of part of a polyethylene terephthalate thread stressed by bending. In the drawing, a thread with the diameter d is placed under tension by bending to a radius r , so that a small part of the thread AB of the order of magnitude of the thread diameter d extends over an angle Φ at the center of the curvature. At the inner curvature of the thread, compression of more than 1 to 2% causes permanent deformation and disorientation of the fiber-forming polymer. It is assumed that this enables the selective, pronounced attack of the chemical agent in comparison with the other parts of the fiber, since the 'order of the thread structure in the curved part' is reduced.

A stretching occurs at the outer curve, which causes further orientation. Because of the Disorientation at the inner curvature of the bent thread, the latter is a stronger one Exposed to attack by the treatment agents. At the outer curve, the bending causes a Orientation, which can be accompanied by crystallization, and for these reasons one should use the Stretching deformation preferably not exceeding 5%, and heating before chemical Treatment should also be avoided. This defines the voltage limits that are caused by the Bending of the threads. As indicated, the bending of the thread should preferably be less than 50 thread diameter to meet the above requirements, according to the formula:

_ | _r --j) Φ

r <P

Ir

> Ibis2%.

The desired crimp can be obtained using a stuffer box crimper with feed rollers of relatively large diameter and by adjusting the pressure in the stuffer box, from which the crimped threads only resist the pressure of a dead weight or hydraulic pressure can escape. Feed rollers from 11.2 to 16.3 cm in diameter and approximately one inch wide were used for crimping 100,000 to 300,000 denier tows in one Stuffer box crimper found effective.

It should be noted that one must apply the chemical agent uniformly in order to achieve the selective weakening of the threads according to the invention. Strong aqueous caustic alkali solutions of 20 to 30 percent by weight can be used at low temperatures, for example at 20 to 40 ° C., for a treatment lasting 30 to 50 hours. The addition of small amounts of catalytic accelerators to the caustic alkali solution, namely methyl alcohol or certain quaternary ammonium salts, accelerates the reaction. Suitable quaternary ammonium salts include cetyltrimethylammonium bromide and lauryldimethylbenzylammonium chloride. The effects of other quaternary salts, such as cetyltrimethylpyridinium bromide, dimethylphenylbenzylammonium chloride and tetramethylammonium bromide, are less pronounced and are therefore not recommended because of the higher treatment costs. If the accelerator is added, the concentration of the caustic alkali solution can be reduced considerably, e.g. B. to 5 or even only 1 percent by weight. When using temperatures close to the upper limit given below, the treatment time can be reduced quite significantly. Very small amounts of accelerator can be used, e.g. B. 0.005 to 1 percent by weight of the solution. It must be emphasized, however, that the treatment must be carried out at a temperature below the heat setting temperature in order to be effective. Obviously, the treatment time can be shortened when using higher temperatures, but since the selective degradation of the crimped threads decreases with increasing temperature, temperatures below HO ⁰ C, preferably from room temperature up to about 70 ⁰ C, are preferred.

5 6

In the case of crimped threads with an overall made, and the polyester denote fiber-forming

strength above 4 g / denier should be the strength of polyester, including polyethylene terephthalate,

preferably reduced to less than 3 and more than 1.5 g / denier mixed polyester with up to 15% of another component

will. In the case of fibers of medium strength, one of the components from the group of dicarboxylic acids

4 g / denier it is desirable to have the total fiber 5 formula

strength to a maximum of 2.5 and at least 1.0 g / rrnnr ¹ τ? rnnw

Decrease denier. Note that a HUUC - R - CUUH
certain diminution of the firmness even of the stronger ones,

Fiber parts located between the crimps in which R is methylene, polymethylene or arylene, but this should preferably be a 10 p-phenylene, such as sebacic, adipic and isophthalic thirds of the original strength ^ not excessively acid, and the remainder polyethylene terephthalate or closing steps. In the case of caustic alkali treatment, Hch modified fiber-forming polyesters such as poly can correspond to a weight loss of up to 10% with- (hexahydro-p-xylylene) terephthalate.
the reduction of the diameter of the threads designate the threads can be an effective deformation acts, and simultaneously therewith will result in a ₅ stage i are exposed, followed by treatment improved feel of the fabric. with a suitable means and if necessary

The invention is particularly described followed by further steps such as heat setting prior to reference to polyethylene terephthalate or after further deformation steps in order to obtain polyester filaments and fibers, the filaments having a greater frequency of crimps. The threads have a practically circular cross-section, for which they do not need to be cut and can be particularly suitable. It should be noted, however, in the form of filamentary yarn treated according to the invention that the invention is not limited thereto and can be processed into fabrics or the like,
The polyester threads can be used in hot, essentially circular cross-section, especially borrowed anhydrous polyethylene glycols and nonyl with a cross-shaped, Y-shaped, trilobal, 25 phenyl polyethylene glycol ether with a molecular bone-shaped or other known cross-section weight from 200 to 2000 at temperatures above for thermoplastic threads. It is similarly applicable 80 ° C, but at least 30 ° C below the melt on other polyester or mixed polyester threads, temperature of the polyester, preferably 110 to which show a tendency to podule, 130 ° C, dipped or sprayed with it, as indicated above . 30 The polyglycols can be used before or after stretching

Polyethylene terephthalate threads are preferred. the polyester threads are applied, and one produced by melt spinning and then achieved a considerable improvement in the dye stretching at a temperature below HO ⁰ C, uptake.

preferably between 80 and 98 ⁰ C. The stretched example 1

Threads are then in the form of a cable, a 35

Subjected stuffer box crimp treatment, A 275,000 denier tow made from 70,000 polyethylene

a deformation of the threads under bending in terephthalate threads is carried out in a stuffer box

At intervals with a curvature of less than curling device so that they are 10 to 14 curling

50 times the diameter of the thread and one size per inch (2.54 cm). The ruffled,

Frequency of 5 to 18 crimps per 40 inch but unfixed cable is obtained by immersion

(2.54 cm), depending on the case, between 1 and 22.5% aqueous sodium hydroxide solution

5 denier per thread lying thread diameter, treated at 30 ° C for 40 hours. Excess solution To learn how to achieve the desired crimp. is removed by nip rollers, and the cable

The crimped tows are then treated, washed with water, dried, with steam

subjected to the specified chemical agents, heat-set 45 at 130 ° C and turned into staple fibers of the

which are removed again, e.g. B. cut desired length by neutral. When examining a

size with a dilute solution of a strong acid, number of threads from the treated cord in

are rinsed with water, then dried and found on a tensile tester that the

a temperature above HO ⁰ C, preferably break always at the apex of the crimp

using steam at superatmospheric 50 occurs and the strength of the individual fiber at the

pressure and temperatures from 130 to 150 ° C and at the specified location in comparison with an uncertain

Use is reduced by dry heat up to 22O ⁰ C, treated control fiber by 94%.

heat set. The fixation is necessary in order to reveal the fabric made from the treated staple fibers

residual shrinkage in boiling water while no nodule formation, whereas tissue made of un-

1 minute to less than 1%. 55 treated fibers show numerous nodules.

Suitable finishing lubricants may be applied before or after heat setting of a crimped cable to facilitate pre-sodium hydroxide processing and to prevent solution build-up as in Example 1 using static electricity steam. The crimped, is heat-set at 14O ⁰ C for ^x / ₂ hour, treated and heat-set cable 60 are then reduced by only 32%,
to staple fibers of the desired length, e.g. B. between ". . _{1 0}
Cut 1.5 to 7 inches (3.81 to 17.78 cm). B e 1 s ρ 1 e 1 2

A cable of polyethylene terephthalate filaments can be made from these staple fibers according to known methods

Methods including weaving and knitting are crimped, and the crimped tow is made, as in US Pat

improved fabrics are produced, which an improved 65 Example 1, treated with sodium hydroxide solution

have a reduced tendency to form nodules. and washed. The treated cable is in comb

The polyester threads mentioned in the description train or yarn converted after a stretch break

and fibers are processed according to a taste spinning process, which is set up in such a way that the

desired stack length between 2.5 and 6 inches (6.35 to 15.24 cm).

The conversion of the cable to sliver or yarn is made easier, since only lower stretching forces are required because the alkaline treatment is at the vertices of the crimps Has produced lower tensile strength and the cable breaks more easily while delivering the desired Fiber length. In the staple fibers, therefore, there are no undesirable excess and short lengths.

In the following examples 3 to 6 attempts are described to the effect of fixing to a imitated crimping of polyethylene terephthalate yarn under various conditions of the Treatment with caustic soda solutions with and without an accelerator to explain. Besides, the test method used to determine the breaking load and elongation of the yarn is described. in the The following raw materials and methods were used:

Polyethylene terephthalate - ("Terylene") - 75 - denier 36-ply yarn with a tenacity of 4.5 to 5.5 g / denier and an elongation at break of 27 to 17%.

Krausem:

The yarn was wrapped around a 2 cm wide strip of 0.25 mm thick copper foil, placed between polished steel plates, and subjected to a pressure of 236 kg / cm ² in a hydraulic press for 5 minutes to obtain a simulated crimped yarn in which each Thread is deformed by compressing beyond the elastic limit, if this is 1 to 2%, at the inner curvature of the bent threads.

Fix:

40

The yarn was subjected to dry heat fixing by one treated 10 minutes at 140 ⁰ C in an electric heating cabinet. Other samples of the same yarn were fixed with steam in a Sanderson furnace at a steam pressure of 2.80 kg / cm ² , corresponding to a temperature of 140 ^° C., for 15 minutes.

Treatment:

The crimped yarn, depending on whether it was fixed or not, was placed in a 100 cm ³ flask with an uncrimped control sample and treated as described. After the treatment, the samples were thoroughly washed with water and dried.

Test:

Lengths of yarn with only one crimp were placed on cardboard, the location of the crimp was marked, and the fiber breaking load and elongation at break were determined with an »Instrone tensile tester. The values given in the following tables are each the mean of ten tests.
The uncrimped samples were tested similarly.

Example 3
Effect of fixing the crimps

The treatment time was 30 hours using a 20% (w / v) sodium hydroxide solution at room temperature and the results are shown in Table I. Unfixed, dry heat set and steam set yarns, both crimped and uncrimped, have been used before as well as after the treatment with caustic soda regarding breaking load and elongation at break checked. From the table it can be seen that the effect obtained leads to considerable differences in the Tensile strength between the crimped and uncrimped part of the threads leads and that one this Effect on the unfixed fiber is obtained, where after the treatment the crimped fiber is 48% weaker was than the uncrimped fiber. The fixed fibers do not show this significant difference in strength.

With dry heat set fibers, the difference is between crimped and uncrimped Samples both before and after treatment at approximately 6% were crimped steam set fibers twice as weak compared to uncrimped fiber after treatment as above, during the The difference in breaking load was only 21%.

In each case, the unfixed treated samples broke at the crimp when tested during the control samples, as well as the fixed curled samples, did not always break at the curl.

Table I.

Effect of fixation treatment: 30 hours at room temperature in 20% (w / v) NaOH

yarn

Uncrimped
Breaking load elongation

Ruffled
Breaking load I elongation

% Difference
Breaking load I elongation

Unfixed

control

treated

Heat set dry

control

treated

Steam fixed

control

treated

342
241

41.0
28.2

38.6
26.5

38.8
34.2

276
147

319
227

298
229

24.4
14.0

36.5
23.7

35.9
17.0

22nd
48

6.7
5.8

14th
21

40.5
51

4.9
10.5

7.5
50.5

Example 4

Effect of concentration

Unfixed crimped yarn and uncrimped control yarns of the type described were used for

10

Investigation of the effect of different alkali concentrations and treatment times used. The results are summarized in Tables II and III. The difference in strength of the crimped and uncrimped fibers both increased with the concentration as well as the duration of the treatment.

Table II

Effect of concentration Unfixed Gam treated at room temperature for 30 hours

concentration
the NaOH

Uncrimped Breaking Load I Elongation Crimped
Breaking load I elongation

Uncrimped
Breaking load I elongation

5 ° / o
10%

15%
20%

25%
30%

330 32.5 268 22.9 18.8 30.4 320 32.6 252 24.0 21.2 26.4 336 32.0 232 16.5 31.0 48.5 283 28.2 147 14.0 48.1 50.4 243 24.0 117 12.3 51.6 48.7 254 28.3 90 9.9 64.6 65.0

Table III

Influence of the treatment time
Unfixed yarn treated in 20% (w / v) NaOH at room temperature

Treatment time

Uncrimped Breaking Load I Elongation Crimped
Breaking load I.

Uncrimped strain hunch Breaking load 40.3 24.4 16.1 33.8 21.6 19.5 44.2 17.0 33.8 46.8 14.0 45.3 67.3 8.3 67.2 77.5 2.4 90.3

control

7V ₂ hours
23V ₂ hours
31Va hours
50 hours ..
95Va hours

329 303 272 256 228 194

40.9 32.6 30.5 26.3 25.4 21.0

276

244

180

140

Example 5

Examination of the effect of temperature produced the results shown in Table IV. The treatment time was changed, to obtain a curled fibers, and the results showed that the treatment decreased rapidly at temperatures above 5O ⁰ C, the difference in strength between crimped and uncrimped yarn with increasing temperature. That could affect the fixation effect

constant value for the strength of the un- 45 the hot liquid can be attributed.

Table IV Effect of temperature

Handles temperature

Time minutes

Uncrimped Breaking Load Elongation Crimped
Breaking load elongation

% Difference

Breaking load

strain

100 ⁰ C
90 ⁰ C
80 ° C
7O ⁰ C
6O ⁰ C
50 ° C

2O ⁰ C

3.5 7.5

18th

36

88 168

1800

287 287 277 302 285 283

283

30.2 31.5 29.7 33.6 30.6 32.2

28.2 257
249
239
240
199
172

147

22.3
22.1
22.0
21.6
17.2
15.4

14.0

10.5
13.2
13.7
20.5
30.2
29.2

48.0

26.1
29.8
25.9
35.7
43.8
52.2

50.5

., Examples

" ^I polyethylene terephthalate yarn is treated at room temperature with 20% sodium hydroxide solution, to which 1% lauryldimethylbenzylammonium chloride (sold under the name" Vantoc CL ") is added. The results of the treatment of uncrimped and crimped threads for 1 to 7 hours and the differences in Tensile strengths and the percentage differences

609 749/391

between uncrimped and> crimped samples are listed in Table -V. As can be seen, after only 6 hours the crimped yarn is too weak for a determination of tensile strength. When comparing the time to get a 50% difference the strength between crimped and uncrimped yarn can be seen that the use 1% accelerator ("Vantoc C. L.") accelerates the reaction 26-fold, i.e. to 1.3 hours in comparison with 34 hours in example 3.

Table V Effect of the accelerator

Treated unfixed yarn at room temperature with a 20 ° / ₀ by weight (wt./vol.) Solution with NaOH l ° / ₀ content of lauryldimethylbenzylammonium

Treatment time Ungeki
Breaking load äuselt
strain Creep
Breaking load owls
strain % You
Breaking load Terence
strain 1 hour 299
294
267 38
34
30th 161
127
104 16
12th
9 46.1
56.8
61.2 58
62
70 2 hours 277
224
197 VO VO ■> *
CS CS CS 80
30th 5
2 71.2
86.5
100 81
92
100 ' 3 hours 191 21 - - 100 100 4 hours 5 hours 6 hours 7 hours

Example 7

This example illustrates the effect of the treatment on nodule formation. A crimped stuffer box unfixed stretched polyethylene terephthalate tow was left in place for 30 hours at room temperature treated in 20% aqueous sodium hydroxide solution, washed with water, dried, Fixed in air at 140 ° C for 10 minutes, in 2 inch lengths (5.08 cm) and the resulting staple fibers were trimmed with a conventional cotton machine was converted to cotton-type spun polyester yarn, and this yarn was woven into a twill fabric which is susceptible to pilling has been checked.

Table IV compares the properties of the fiber at various stages of fabric manufacture with untreated 2 inch polyester staple fibers of the cotton type. As can be seen, an improved behavior in terms of nodule formation is achieved at the expense of decreased flexural abrasion resistance and tensile strength. The lower elongation at Breakage of the treated fiber is a particular benefit when the fibers are blended with cotton.

Table VI Fabric Manufacture

Units of production Fiber form characteristic unit Untreated
fiber Treated
fiber cut
fiber Fiber length
denier
strength
strain cm
0 /
/ 0
g / den.
0 /
/ 0 5.08
3
5.37
30th 5.08
3
2.38
18th Spinning: fiber spun too
2 / 18.7's cc of yarn with
lOZ single and 5S
double twist Single yarn
(1 / 18.7's)
Double yarn
(2 / 18.7's) strength
strain
strength
strain g / den.
0 /
/ 0
g / den. 2.42
30.3
2.77
32.2 1.42
17.7
1.45
17.9 Nodules
education
(Sponge Nodules
Per
6.46 cm ^a 28 8th Weaving: yarn woven into one
2/2 twill fabric, 81.3 cm wide,
52 x 52 ends X wefts
per inch finished setting finished fabric < test
200 minutes)
Bending
abrasion number
Bends
until
fracture 6000 1800 Flat abrasion similar

It can be seen from the examples that

1. Unfixed curled fiber by strong aqueous Caustic soda solution is attacked preferentially at the crimp apices;

2. Crimped fibers set by both steam and dry heat are preferred Do not suffer attack to the same extent;

3. the addition of quaternary ammonium salts to the caustic soda solution, the rate of attack elevated;

4. Fabric or the like made from treated fiber. An improvement in nodule formation shows in comparison with untreated fibers.

The brush and sponge test in the example? is described in the American Standard ASTM 1958 D 1375-55T, p. 515.

Claims (8)

Patent claims: 1. Procedure for the treatment of oriented * 5 synthetic polyester threads or fibers with a chemical agent such that the threads or fibers are locally weakened, characterized in that the treatment of threads or fibers with the marriage ae> mix agents before processing into textiles and before heat setting, but after Crimping takes place, the crimp being produced by the filaments being sharply bent and thereby the inner curvature of the threads is given a compressive stress that is beyond the elastic limit, which is reached when the pressure is applied by bending. 2. Method for handling crimped, oriented synthetic polyester threads according to An-Spruch 1, characterized in that this after stretching in the form of a crimped cable are chemically treated and then, before or after cutting into staple fiber lengths, the crimp to reduce the residual shrinkage that occurs in boiling water during one minute to less than 1% is heat set. 3. Method for treating crimped oriented synthetic polyester filaments according to Claim 1, characterized in that this in the form of a crimped cable after Stretch are chemically treated and then, before or after stretch breaking of the threads by a tow-to-top process, the crimp to reduce the residual shrinkage occurring in boiling water during one minute to less than 1% is heat set. 4. The method according to any one of claims 1 to 3, characterized in that the threads through Bend to a curvature of less than 50 thread diameters according to the formula τΦ Ibis2 ° / o, where d is the filament diameter, r is the radius of curvature, and Φ is the angle made by a filament element with the center of the curvature. 5. A method for treating crimped oriented polyester filaments or fibers according to one of claims 1 to 4, characterized in that as a chemical agent at least one of the following: sodium hydroxide, ammonia, certain quaternary ammonium salts, methyl alcohol, Hexamethylene diamine, polyethylene glycols and nonylphenyl polyethylene glycol ethers can be used. 6. A method according to any one of claims 1 to 5, characterized in that the chemical agent comprises a 5 to 30 ° / _o aqueous Natiiumhydroxydlösung and optionally as quaternary ammonium salt, cetyl trimethyl ammonium bromide or lauryldimethylbenzylammonium chloride. 7. The method according to claim 6, characterized in that 0.005 to 1 weight percent of the quaternary salt can be used. 8. The method according to claim 1, characterized in that the polyester is up to 15% contains other component, namely one from the group of the dicarboxylic acids of the formula HOOC-R -COOH wherein R is methylene, polymethylene or arylene, except p-phenylene, such as Sebacin-, Adipin- and Isophthalic acid, the remainder being polyethylene terephthalate, or modified fiber-forming Polyesters such as poly (hexahydro-p-xylylene) terephthalate. Considered publications:
Austrian Patent No. 184 663;
Swiss patents No. 221 902, 315283; British Patent No. 847 147. 1 sheet of drawings 609 749/391 12.66 © Bundesdruckerei Berlin