DE1301471B - Process for producing weldable threads from rubber mixtures - Google Patents

Description

i 2

Most, if not all synthetic fabrics, from threads from the coagulate, washing in water, especially those that form fibers and, as a replacement, drying the threads and vulcanizing in one of natural rubber have been proposed, a hot air oven characterized in that remain in their properties compared to this only latex mixtures are used, the 60 to 90 types Material, especially in its speed - 5 percent by weight natural rubber and 40 to 10 percent by weight elastic recovery from the deforma- weight percent of a synthetic rubber tion, which is often referred to as a "snap", contain a base of acrylic compounds, and in their strength in normal household laundry. According to the invention, natural rubber with the

return. Polyurethanes, when mixed with more synthetic rubber than latexes, possess. the 85% of a segmented polyurethane, the mixture obtained then suffers from the following disadvantages. In detail, these are mixed together in the usual way. The synthetic

Rubbers, which are generally usable, contain from 50 to 90 percent by weight of a con-

1. Sensitivity to degradation by chlorine in jugated dienes and 50 to 10 percent by weight of one of the household bleaching agents; ¹ S acrylic based monomers. As conjugated service

come butadiene or its homologues and derivatives of butadiene, such as isoprene, 2,3-dimethylbutadiene,

2. Inability to wash in very hot water 2-chlorobutadiene and 2-cyanobutadiene in question. Butadiene is the preferred hydrocarbon monomers due to its lack of dimensional stability. _{ao The} unsaturated acrylic based monomer is made from

from the group acrylonitrile, methacrylonitrile, acrylic or

3. Risk of hydrolysis of the polyester under normal methacrylic acid, its amides and their esters with alkaline washing conditions; Derived from alcohols with 1 to 3 carbon atoms.

The preferred monomer is acrylonitrile. In particular

. ", .J .... .... r, .... . . Other than that, no more than 4% acrylic or meth-

4. garments with these fibers can not _acr y _{L acid with butadiene and A} ° _cryln i _ril "^ poly-

given that. merized to give additional tensile strength.

The preferred synthetic rubber therefore consists of 63% butadiene, 35% acrylonitrile and 2%

The synthetic elastomers also contain methacrylic acid. The preferred ratio of natural disadvantages compared to rubber, since rubber consists of synthetic rubber they don't have the highly elastic rebound, 20% synthetic rubber and 80% natural those for the purposes of the invention in the sizes rubber. The mixture is made with the usual Order of 95% or higher in half a minute of normal natural chewing agents required are held at an elongation of 150% after they have vulcanized 35 chuk for half a minute. As a theoretical explanation, the following is tentatively

Natural rubber has none of these disadvantages. It has been established by others and still remains the best elastomer on which the degradation reaction caused by squalene is one Textile area. However, it is subject to degradation through oxidative degradation and that oxidation is caused by the influence of chewing and perspiration, if it proceeds through a free radical chain reaction in objects of the person, Borrowed clothing is used that is placed on the skin The usual antioxidants act as chain terminators or be worn very close to the skin, as well as by medium and react mainly with the active ones Dry cleaning solvent. Natural chewing radicals before they react with the rubber Tschuk is currently rarely able to incorporate it into clothing and dismantle it. Squalene is chemically similar worked, which are dry cleaned, since other 45 the natural rubber hydrocarbon, is Substances such as butadiene-acrylonitrile-rubber fibers, however, oxidize more quickly. So is squalene in that if the rubber described in British patent specification 982 523 is present, it will be any antioxidant have been specially developed for this purpose. tion agent that is present in it to the rubber Sweat depletion is therefore the only major drawback to protect, consume and demolish the rubber which must be overcome in order to expose natural chewing oxidative attack. By mixing the Tschuk in all respects the synthetic elasto-natural rubber with, for example, a boomer - as far as they are known so far - superior tadiene acrylonitrile rubber is a physical one close. Barrier created against the movement of the free

It has been established by other sources that radicals, due to the indiscriminate distribution of the

Reason for active degradation when exposed to sweat 55 synthetic rubber. The natural rubber

Squalene is an acyclic dihydrotriterpene that is present in molecules so it will remain intact for a long time.

3.3 to 8.7% is contained in sweat. It is confirmed regardless of the mechanism of the invention,

The following example shows how the desired squalene is actually degrading

accelerated quite alarmingly. It is therefore results to be obtained a rubber compound for particular use for 60
threads pressed out of latex have been developed,

which is relatively stable against degradation by squalene, Example 1 while it has all of the desirable properties

of natural rubber. Centrifuged, weakly ammoniacal, concentrated

The invention relates to a method of making 65 trated natural rubber latex with 61.5% weld strength Threads made from rubber mixtures due to their velvet solids content, by adding 0.5% Stabilizing latices, mixing, aging, deaerating, caustic potash and 1% potassium oleate soap stabilized. Of the Coagulate the latex mixtures with acids, pulling stabilized latex is then mixed as follows:

Mass A

Stabilized natural rubber latex

Butadiene-acrylonitrile rubber latex

Zinc oxide

Dipentamethylene thiuram tetrasulfide

N, N ¹ -di / 3-naphthyl-p-phenylenediamine

Titanium dioxide

Inorganic blue pigment

Parts by weight

on dry

Rubber content

100

25th
5.0

2.2

1.0
5.0
0.2

The mixture was left to stand for 5 days for the purpose of aging and then, after venting under vacuum, passed through a glass capillary into 20% acetic acid solution. The strand thus produced was pulled from the acid with a roll and passed into a wash bath with water at approximately 5O ⁰ C in order to remove excess acid. The washed thread was then fed onto an endless belt into a tunnel dryer and the dry thread that came out in this way was placed in a hot air oven at 70 ^° C. to terminate the vulcanization. The thread produced in this way has a modulus of 24 kg / cm ² at 500% elongation, a tensile strength of 310 kg / cm ² and an elastic springback of 97 ° / ₀ .

The thread was tested for weld strength using squalene as follows:

Sufficient 2 inch loops of the suture for a load of 850 to 1150 grams at 200% elongation were used and left on a jig at 200% for 30 minutes. The load then required to maintain an elongation of 200% was measured. The thread, still at 200% elongation, was then soaked in a fresh 5% squalene solution in isopropyl alcohol at ambient temperature for 24 hours and the load measured again at 200% before the jig and thread were placed in a hot air oven at 70 ° C. The remaining exposure was measured once a day. Heating at 7O ⁰ C was used to accelerate the degradation which may take place to produce a result in hours instead of weeks to arise. This test was also carried out on a thread sample, made of the same mass as mass A, but with the omission of butadiene-avrylonitrile rubber. This thread was designated mass B.

Retained exposure at 200% Stretching after 24 hours 41 hours at 7O ⁰ C at 70 ⁰ C sample to the 17 hours Thread ge Thread ge Soak at 70 ⁰ C broke broke in squalene
solution 70.2% on two at seven Mass B 83% Place Place 59.4 "/ ₀ 58.4% 59.8% Mass A 69.5%

To show that the above aging is due to the

Squalene decreases, a separate experiment was carried out, identical to the one described above, with the exception that the two compositions were soaked in isopropyl alcohol prior to aging at 70 ° C.

sample

Mass A
Mass B

Left exposure at 200%
Stretching after

the watering

in isopropyl

alcohol

95%
98%

41 hours
at 70 ⁰ C

116 hours at 70 ^° C

77.4%
81.5%

69.3%
76.4%

Example 2

Centrifuged, weakly ammoniacal, concentrated natural rubber latex with 61.5% total solids content was stabilized by adding 0.5% caustic potash solution and 0.6% potassium oleate soap solution. The latex was then mixed as follows:

Mass C

Stabilized natural rubber latex

Butadiene-methyl methacrylate copolymer latex

Zinc oxide

Dipentamethylene thiuram tetrasulfide

Base antioxidants
of condensed phenolic resins

Titanium dioxide

Inorganic blue pigment

Parts by weight

on dry

Rubber content

100

25th
5.0
2.2

1.0
5.0
0.2

The above-mentioned synthetic rubber latex was made from a mixture of monomers of 65% Butadiene, 33% methyl methacrylate and 2% methacrylic acid.

A thread was prepared in the same way as in Example 1 and had a modulus of 10.85 kg / cm ² at 300% elongation.

The thread was - as in Example 1 - tested for weld strength together with a thread sample, which was prepared according to the same recipe as compound C, omitting the synthetic one Butadiene methyl methacrylate rubber latex. This latter thread is identified as mass D. the The following results were obtained

sample

Mass C
Mass D

Retained Charge at 200%
Stretching after

to the
Soak
in squalene solution

88.0%
90.0%

hours
at 70 ⁰ C

83.4%
80.4%

70

hours
at 7O ⁰ C

120

hours
at 70 ⁰ C

74.6%
73.8%

61.2%
45.57o

Claims (3)

Patent claims: 1. Process for producing weld-resistant threads from rubber mixtures by stabilizing Latices, mixing, aging, deaerating, coagulating the latex mixtures with acids, pulling threads from the coagulate, washing in water, drying the threads and vulcanizing in a hot air oven, characterized in that latex mixtures are used, the 60 to 90 percent by weight natural rubber and 40 to 10 percent by weight of a synthetic rubber based on acrylic compounds. 2. The method according to claim 1, characterized in that one is used as synthetic rubber Butadiene-acrylonitrile copolymer used. 3. The method according to claim 2, characterized in that one is a synthetic rubber made of 63% butadiene, 35% acrylonitrile and 2% methacrylic acid.