DE2055320A1 - Polyvinyl alcohol fibers and radial tires containing polyvinyl alcohol fibers - Google Patents

Description

Kuraray Co., Ltd. DA-5039 J ^ T

Patent attorneys

Bo. - * npU

! tart not i) t = rn: - 'Mil,

i Polyvinyl alcohol fibers and those containing polyvinyl alcohol fibers

Radial tires

Priorities: November 25, 1969, Japan, No. 44-94790 April 30, 1970, Japan, No. 45-37354

The invention relates to polyvinyl alcohol fibers with excellent high temperature properties, such as yarn tenacity, Yarn initial modulus and yarn creep behavior. It also relates to radial tires, where this Fibers can be used as cord for the belt or breaker by twisting them under given conditions.

In general, polyvinyl alcohol fibers (PVA) are different from synthetic fibers in terms of their breaking strength and their initial modulus think. Their application is therefore very recently in the field of fiberglass reinforced plastics (FRP) spread. It is a known fact that PVA fibers are stretched to their yield point and through

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subsequent heat shrinkage can be shortened via a have excellent breaking strength and an excellent initial module. However, PVA fibers tend similarly other synthetic fibers contribute to their properties high temperature proportional to the temperature increase deteriorate significantly.

An essential aim of the invention is therefore to avoid the above-mentioned disadvantages in synthetic fibers, by creating new PVA fibers with excellent properties at high temperature as well as radial tires where these fibers are used as cord for the belt or breaker. The synthetic fibers according to the invention are particularly superior to conventional PVA fibers in terms of their yarn tenacity, their yarn initial modulus and their Yarn creep. The radial tires in which the PVA fibers according to the invention are used as cord for the belt or breaker therefore, as will be shown later, have excellent properties for push rod or plunger test, high-speed test, walk or Corner test, tread wear resistance test and Durability test.

The PVA synthetic fibers and the radial tires are described in more detail below.

I. The PVA synthetic fibers according to the invention are highly crystalline and oriented and are characterized by

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favorable properties at high temperatures as well as a content of boric acid (Η, ΒΟ,) or borate. It applies to them the following:

Garnzähfestigkeit at 120 ⁰ C Garninitialmodul at 120 ⁰ C Garnkriechen at 135 ° C boric acid

7 * 5 g / d and above 100 g / d and above 2 % and below

0.2 to 0.9 weight percent based on weight to PVA.

In general, the stretchability of synthetic fibers increases in proportion to the increase in temperature, and so does the strength as well as the yarn initial module can decrease. This phenomenon can be interpreted by assuming that the The movement of the molecular chains caused by the heating begins in the fibers with a lower molecular orientation and soon reached the state of high molecular orientation. To improve the high temperature properties of synthetic fibers, it is therefore important to control the movement of the molecular chains to suppress as much as possible. This can be achieved by (l) orienting the molecular chains so strongly that that they can no longer move, or (2) certain substances are added to the polymers that inhibit the movement of the molecular chains inhibit. If these two agents are used separately, however, those desired according to the invention can be used Not achieving goals, namely the improvement of the properties at high temperatures, such as the yarn

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tough, the yarn initial modulus and yarn creep. An improvement in the yarn initial modulus can be expected, for example, from a process in which conventional PVA fibers are aftertreated with boric acid. At the same time, however, a considerable decrease in yarn tenacity is associated with this process. Numerous investigations therefore suggested that the essential factor for achieving the goal of the invention is a fibrous structure in which the molecular chains are generally very highly oriented, but which contains a substance to prevent the movement of the molecular chains where the said molecular orientation is relatively low. This means that some or all of the boric acid present in the fibers can combine with the PVA in a relatively loose orientation in order to prevent the movement of the molecular chains caused by heating. If the content of boric acid is less than 0.2 wt -.%, Based on PVA, so this is not sufficient to brake the movement of the chain, while above 0.9 wt -.% Beyond amount prevents a high orientation of molecular chains and thereby at the same time the yarn strength deteriorates.

The PVA fibers according to the invention can be obtained by adding an aqueous solution containing boric acid or borate of PVA (spinning solution), which spins it into a coagulating bath consisting primarily of water, which determines Contains quantities of sodium or potassium hydroxide and sodium sulphate, the threads obtained are stretched by means of rollers Alkali adhering to the fibers is neutralized by acid,

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the piping stretched wet, warm, to adjust to one A certain amount of boric acid remaining in the PVA fibers is rinsed with water, drained, dried and finally dry warm stretched.

As for the preparation of a suitable mixture for the coagulating bath, it should be noted that one for conventional Wet spinning process for the production of boric acid or borate-free PVA fibers used coagulating bath with sodium sulfate is almost saturated if sodium sulfate, which serves as a dehydrating salt, is used for the bath. this is done because the fibers have been tightly adhered to each other due to insufficient coagulation when the concentration of this bath would be below 300 g / l. According to the invention For this purpose, certain amounts of sodium or potassium hydroxide are added to the coagulating bath used, whereby the solutions containing boric acid or borate can be spun more easily. In addition, the properties depend of the PVA fibers produced in this way depend only very little on the temperature. Is the sodium sulfate content in the coagulating bath high, it can often be observed that the stretchability of the product is lower. Compared with usual However, boric acid-free PVA fibers, the PVA synthetic fibers produced according to the invention are more stretchable and less temperature dependent.

Various considerations and attempts were therefore made with regard to the coagulating ability of aqueous solutions of PVA containing boric acid or borate and the properties of those with them

2 0 over B 2 3 / over 8 B 9

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products obtained and found here processes and conditions for the production of PVA synthetic fibers, whose yarn tenacity, yarn initial modulus and yarn creep are hardly dependent on temperature. This new procedure exists in that one spins a boric acid or borate-containing aqueous solution of PVA in a coagulating bath that through Addition of 10 - 100 g / l sodium or potassium hydroxide and 100 - 530 g / l sodium sulphate is strongly alkaline, and the fibers obtained in this way are appropriately aftertreated, such as stretching by means of rollers, their alkali neutralized, they to adjust the amount of boric acid remaining in the fibers to 0.2 to 0.9% by weight, based on PVA, with water rinses, drains, dries and finally dry-stretched.

The boric acid or the borate are preferably added to the spinning solution in amounts between 1 and 5 wt .- #, based on PVA, added. The spinning solution is kept slightly acidic, especially at pH., Until pH_. As acids can be the solution inorganic acids are added, such as sulfuric acid, nitric acid or hydrochloric acid, organic acids such as acetic acid, Tartaric acid, or mixtures of organic acids and their salts, such as citric acid and sodium citrate, Acetic acid and sodium acetate, tartaric acid and potassium tartrate, Tartaric acid and sodium citrate.

If the pH value of the spinning solution is below 3 », it is

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The coagulation speed in the coagulation bath is slower, and the system corrodes due to the excessive acidity. On the other hand, if the pH is above 5 », the solution becomes unstable and more viscous, which creates good spinning conditions or the spinning ability is largely lost.

The concentration of PVA in the spinning solution is preferably 10 to 30 wt .- ^. The degree of polymerization of PVA should preferably be above 500. As already mentioned, the spinning solution is placed in a strongly alkaline coagulating bath spun in, which mainly contains water and sodium or potassium hydroxide in quantities between 10 and 100 g / l and Sodium sulfate in amounts between 100 and 330 g / l. A Sodium or potassium hydroxide content below 10 g / l is unfavorable. For example, it lowers the coagulation speed and stretchability or drawability during spinning. Quantities above 100 g / l are against it also undesirable, as the gelling effect of the alkali becomes so strong that the properties of the fibers, such as yarn tenacity, yarn initial modulus and yarn flow become more dependent on temperature. The concentration lies of sodium sulfate below 100 g / l, the gelling effect of the alkali covers the dehydrating and coagulating effect of sodium sulfate. This causes the fiber to swell during coagulation, which also affects the quality of the product negatively influenced. Sodium sulfate concentrations of over 330 g / l, on the other hand, deform the fiber cross-section cocoon-like because of the draining and coagulating effect

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surpasses other influences. Fibers with deformed Cross-sections are more difficult to stretch or draw.

The PVA fibers spun according to the invention according to the above process are then subjected to post-treatments. she are stretched, for example, by means of rollers, their alkali is neutralized by means of an acid, they are stretched wet and warm and to adjust the remaining in the fibers Boric acid amount to 0.2 to 0.9 wt .- ^, based on PVA, rinsed with water. The amount of boric acid after rinsing with water should be over 0.2 wt .- #, based on PVA, because the fibers are at amounts below 0.2 wt .- ^ while could otherwise swell during rinsing. However, when the fibers swell, slacks or looseness form in the fibers, which result in uncleanliness when passing through the rollers, resulting in yarn tenacity, yarn initial modulus and yarn creep become worse.

The disadvantages just mentioned do not occur according to the invention, since the amount of boric acid present in the fibers is either react with PVA to form inter- or intramolecular cross-links, are attached to the PVA chains or unreacted can remain. This is one of the essential features of the invention. However, if the amount of boric acid is over 0.9 wt .- ^, the drawability becomes worse, which is associated with a decrease in the absolute values of yarn tenacity and yarn initial modulus.

It can therefore be said that by selecting the optimal coagulating conditions, the process for making a

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can stabilize known fibers with high stretchability.

Are also set out the conditions for the water flushing so that the remaining residual amount of boric acid from 0.2 to 0.9 wt -.% Is, we arrive at a product with nearly temperature-independent properties, without the Trockenwarmverstreckbarkeit is lowered.

According to the invention, it is necessary to carry out the warm dry drawing of the PVA fibers after rinsing with water, dewatering and drying in order to achieve a total draw ratio of over 150%. If the total draw ratio is less than 1300 #, it is difficult to obtain PVA fibers with the properties mentioned above. The PVA fibers obtained according to the invention, on the other hand, can be drawn up to a total draw ratio of 100 % .

The thus obtained PVA fibers have the following properties sheep: Garnzähfestigkeit at 120 ⁰ C of more than 7.5 g / d ^ Garninitialmodul at 120 ° C of more than 100 g / d and Garnkriechen at 135 ° C of less than 2% (stretching rate at a load of lg / d for 60 minutes). They contain 0.2 to 0.9 wt .- ^ boric acid. The fibers are superior to conventional boric acid or borate-free PVA fibers in terms of their properties at high temperatures.

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Determining the remaining in the synthetic fibers The amount of boric acid is carried out as follows:

A PVA-related fiber weighing about 2 g is placed in a crucible and covered with 0.1 molar aqueous sodium hydroxide solution. The mixture is allowed the whole to stand overnight in an oven at 105 ⁰ C, and then heated in an electric furnace 60 minutes to 400-500 ⁰ C. The fiber in the crucible is then placed in a beaker, and to add ion exchange water is added and the all stand for 60 minutes. A few drops of phenolphthalein are then added as an indicator and 0.1 molar hydrochloric acid is added until the color changes from red to yellow. The mixture is then heated to boiling for 30-60 minutes, cooled and neutralized to pH 7 with sodium hydroxide or with hydrochloric acid, after which mannitol is added and neutralized again to pH 7 by titrating with 0.1 molar sodium hydroxide solution. The volume (<Jm) required for titration is determined. The amount of boric acid present in the fiber is calculated according to the following equation, where W (g) is the weight of PVA in the test product, which was determined by the method given above, and f and ν (cnr) are the strength and the titrated, respectively Volumes of a 0.1 molar aqueous sodium hydroxide solution are:

0.62. f. ν W

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II. The characteristics of the manufactured according to the invention PVA fibers with excellent high temperature properties are best exposed when the fibers used to manufacture radial tires.

Because of the need to adapt to the ever increasing speeds of automobiles in recent years Years will find tires with improved properties, such as high-speed performance, wear properties and Processing ability, very quickly widespread. This is understood to be the so-called radial tires.

The radial tires contain a carcass made of cord which is arranged parallel to the transverse axis of the tire is * and a belt or breaker that is fitted with a belt or tape-like layer is provided in which a tire cord is substantially parallel to the tire circumference and on the Outside of the carcass is arranged to reinforce the tread or the profile. The radial tire makes a difference Its structure is very different from that of conventional diagonal tires, where the cord is woven diagonally into a cord fabric cut and at an angle of 40 - 60 ° against the The direction of rotation of the carcass or the substructure is arranged. The most salient feature of radial tires is that Presence of a belt-like or band-like layer. The structure with the features mentioned above brings with it Radial tires have many advantages in terms of properties and effects when using tire cord for the belt used for the structure or the properties corresponding to the structure.

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A series of experiments were therefore carried out with radial tires, in particular a tire cord for the belt before finally arriving at a new radial tire for which the PVA synthesis according to the invention fibers are used.

According to the inventive radial tire, a cord made of PVA-synthetic fibers is prepared, containing from 0.2 to 0.9 wt .- ^, relative to PVA, of boric acid or borate include, the Garnzähfestigkeit about 7.2 g / d is at 120 ⁰ C , the Garninitialmodul about 100 g / d is 120 ⁰ C and the Garnkriechen below 2%, and that at a load of 1 g / d for a period of 60 minutes. The twist constant of the thread (ply) of this PVA yarn in the cord is 800-1J500. The cable twist (turns / 10 cm) is guided in a ratio of 80-100% of the pad twist (turns / 10 cm).

In short, the belt or breaker means what the hoop or ribbon is for a barrel. The main ones Qualifications of the material used for the tire cord to manufacture the belt are therefore high toughness as well as high modulus, and the synthetic PVA fibers are well known for these properties. The usual PVA fibers are, however, still imperfect, as their toughness and modulus decrease sharply with increasing temperature, which also applies to other thermoplastic synthetic fibers, for example polyesters or polyamides. The inside of a The tire is also located while driving

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because normally forms in a state of high temperature, about 10O ⁰ C or jammed during driving heat, which is transferred automatically to the radial tire, as the tire cord for the belt is also affected by this temperature rise. A radial tire made using the conventional PVA fibers, the properties of which are highly dependent on temperature, can therefore not perform its primary function of the strong or rigid and non-stretchable belt that monitors the deformation of the tire. Of course, this lack of strength and modulus in conventional PVA fibers can be made up for by increasing the amount of fibers used in a tire. In this case, however, the problem arises that the durability of the tire decreases sharply because the heat build-up or the heat generation increases as a function of the increasing amount of fibers, as a result of which adhesion and fatigue strength decrease.

For this reason, a radial tire is proposed according to the invention, for the production of which the PVA fibers according to the invention with excellent properties at high temperature are used. It was found that the radial tires according to the invention only have the advantages mentioned if the PVA fibers used have a boric acid or borate content between 0.2 and 0.9 wt .- ^, a yarn tenacity of over 7.5 g / d have at 120 ⁰ C, a Garninitialmodul of about 100 g / d comprise at 120 ⁰ C and the Garnkriechen below 2% at 135 ⁰ C.

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These facts apply regardless of the conditions of the construction or the structure of the cord, the heat treatment of the cord or structure of the tire.

One of the factors that must be strictly observed is the construction or the structure of the cord, since the twist number in particular has a strong influence Properties and quality of the end product. There is no one-size-fits-all number of twists that are unique to everyone Material is suitable. It is inextricably linked with the properties of the material. One can therefore choose the appropriate one The number of twists for the conventional PVA fibers or other fibers is impossible on the PVA fibers according to the invention transfer. A number of real driving tests were therefore carried out with tires in which the twist numbers of the PVA pasers used according to the invention were very different, so as to achieve the optimum twist for the Finding out the cord used to make the belt.

Things are made even more complicated by the fact that the properties of a tire are both direct and vice versa are proportional to the twist number. The fatigue strength therefore becomes, for example, with an increasing twist value directly proportionally better, while the module properties, such as roll resistance, flex and corner resistance, are inversely proportional. .

Any type of tire, not just radial tire,

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must therefore meet the various qualifications required. The above-mentioned tests therefore showed that the PVA synthetic fibers according to the invention are very limited with regard to their suitable number of twists in order to produce the cord for the belt of the radial tire therefrom, namely the twist constant of the thread (ply) must be 800-1300 and the Cable twist (turns / 10 cm) are 80 - 100 % of the thread twist (turns / 10 cm). The term "twist constant" used in the present invention is indicated by the letter K in the following equation, where D stands for denier and T is the number of twists (number / 10 cm):

κ = vHd. τ

The number of twists increases as the value of K increases.

If the twist constant of the thread is less than 800, not only does the shape of the cord become very uneven and thus the quality or the appearance of the tire is worse, but the fatigue strength of the cord is also insufficient, so that the cord breaks earlier than the tread or tread wear, resulting in a shorter service life of the tire. The number or the value of the cable twists (turns / 10 cm) has a larger one Influence on the fatigue strength as the thread twist (turns / 10 cm). The durability of the tire is also

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worse if the cable twist (turns / 10 cm) is less than 80 % of the thread twist (turns / 10 cm).

On the other hand, if the twisting constant of the thread is greater than 1300, properties of the PVA fibers, such as high toughness and high modulus, are lost, which means that the advantages of radial tires with regard to rolling resistance, tread or profile strength and flexing or corner strength are lost. The cable twist (turns / 10 cm) should also not go beyond the limit given above, i.e. not more than 100 % of the thread twist (turns / 10 cm), since this not only reduces the tenacity and the modulus of the cord considerably, but also kinking of the cord under relaxation as well as processing and other difficulties arise.

The tire cord is usually subjected to a dip treatment, to give it such an adhesion to rubber. The adhesive used according to the invention is not limited to certain types, but any adhesive used in the rubber industry can be used is common. RFL, a mixture of an alkaline initial condensate of resorcinol and formalin with latex, is special preferred, or one that contains polyvinylpyrrolidine instead of latex. The conditions of the immersion treatment can same as used in treatment methods for cord

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conventional cross-ply tires can be used. The drying, curing in the heat drawing and heat treatment are carried out at temperatures above 200 ^0C.

In order to carry out the invention, any material can be used for the carcass or the substructure is used to produce the usual bias tires.

The invention can also be used for the production of diagonal tires provided with a belt or a band, which have a belt-like or band-like layer of tire cord which runs essentially parallel to the tire circumference and outside the carcass for reinforcement the tread or the profile is arranged, such as

this is the case with radial tires, but the carcass has the same structure as the normal one Bias tires.

Before the invention is explained in more detail with reference to the examples, the various test methods will now be described which were used to determine the properties of radial tires.

A. Plunger test

The result is determined from the occluded energy (kg. cm) before the tire breaks due to the slow penetration of the plunger. The internal pressure of the tire is

2
1 * 7 kg / cm. The higher the value, the stronger or stronger the tire.

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B. High speed test

According to MVSS No. 109 (ASTM), tires adjusted to a pressure of 1.7 kg / cm are left at 80 km / h. on a Start the test drum. If there is no damage to the tires after a predetermined running time, the speed gradually increased. The result is determined by the maximum speed (km / h) at Breaking the tire and the running time (minutes) at the same speed. The larger this numerical value, the greater the high-speed strength.

C. Flexibility or corner strength

The flexing or corner force (kg) of a tire adjusted to a pressure of 1 * 7 kg / cm is measured at a speed of J> 0 km / h, a load of 125 kg and a grinding angle of 10 °. The value obtained by dividing the flexing or corner force by the grinding angle gives the flexing or corner strength (kg / degree). The larger this value, the better the flexing or corner properties.

D. Abrasion resistance of the tread or profile

You leave an automobile with its tires on a pressure

ο
of 1.7 kg / cm are set, on a test track f

After a distance of 20,000 km at one speed »

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speed of around 80 - 100 km / h. is the abrasion of the Tread or profile that touch the ground, measured. The abrasion resistance of the tread or the Tread is expressed by the distance that the tire travels until 1 ram has been rubbed off by it. The bigger this value is the greater the abrasion resistance of the tread or profile.

E. Durability

You leave a car with tires at an air pressure of

1 * 7 kg / cm are set, on a test track 20,000 km at a speed of about 80 - 100 km / h. to run. By examining the tire cord of the belt or breaker The strength of the cord is determined before and after the test run. It is expressed in the residual strength (#) of the Cord of the tested tire compared to the original cord. The higher the value, the higher the durability.

In addition, it should be noted that the PVA synthetic fibers with improved high temperature behavior are also known as Have the pulling part used for V-belts and to reinforce hoses. High modulus and low creep at high temperatures are the guarantee for V-belts with constant dimensional stability. High pressure hoses, like they are used for oil pressure operated machines and tools are also better by using the invention PVA fibers, as opposed to the expansion of the hose due to the high modulus at high temperatures the internal pressure is kept low.

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Example 1;

1.7 kg of PVA with a degree of polymerization of 1750 and a saponification number of 99.5 Mol-Ji as well as 34 g of boric acid and a small amount of nitric acid required to adjust the pH to 4.3 are mixed to 10 kg of aqueous PVA solution . This spinning solution is spun through spinnerets with 600 spinning holes 0.08 mm in diameter into a coagulating bath which contains 30 g / l sodium hydroxide and 230 g / l sodium sulfate. The fibers spun in this way are then pulled out of the bath at a speed of 10 m / min, and then subjected to post-treatments, such as whale stretching by 100 %, neutralization in a bath with 70 g / l sulfuric acid and 300 g / l sodium sulfate, hot wet stretching by 150 %, rinsing with water to adjust the boric acid content to 0.45%, dehydration and drying and finally hot dry stretching to 220%. The end product thus obtained is stretched to a total stretching ratio of 1500 %.

The product then has a Garnzähfestigkeit of 9.3 g / d at 120 ⁰ C, a Garninitialmodul of 135 g / d at 120 ⁰ C and a Garnkriechen of 1.4% at 135 ° C.

PVA fibers according to the invention are used to produce radial tires for passenger cars with the size I65-13 with 1200 d / 600 f (f is the number of threads) used for the belt or breaker, while high-tenacity rayon Super-2 with

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1650 d / llOO f is used for the carcass. Both yarns are twisted and processed into cord fabric with the characteristics given in Table 1.

Table 1

Classification material A 1200 d / 1/3 Material B construction I65O d / 1/2 Gluing resp. Twist number: 30th Thread (ply) (turns / 10cm) 25th 50 Cable ( " " ) 50 Cord twist con 1039 stante of the thread 2031 Cable twisting or twist / Thread twinning or twist χ 100 {%) 100 Twist direction; Thread twinning or PIy- Z twist S. Z Cable twisting 32 S. Cord density (ends / 5 cm) 49 tissue

Both cord fabrics A and B are in the usual way RFL solution submerged. The cord fabric A is then 3 minutes

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dry heat-treated at 200 ° C., the cord being stretched by 2.5%. The cord fabric B is dried at 150 ⁰ C, however, and its original length.

Using the above-mentioned cord fabrics to form the belt or breaker and the carcass one arrives
by conventional methods such as rubber dipping, tire molding, vulcanization and post-curing to give the tire of the present invention. However, the present tire was built up from 4 layers or. Plys in the belt or breaker and 2 layers or plys in the carcass.

The results of various tests on the properties of the tires are shown in Table 2. Radial tires were used as comparison samples, their structure and
Largely resembled the tire according to the invention, for which, however, PVA fibers were used for the production of the belt or breaker, which did not meet all the production conditions and properties of the invention. The test results of the comparative examples are also shown in FIG
Given in the table.

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Tabel example

1

Comparative Examples 5 4. 5 "

Material:

Degree of polymerisation of the PVA

Saponification number of PVA (MoI-Ji)

1750 1750 1750 1750 1750 1750 1750 1750 99.5 99.5 99.5 99.5 99.5 99.5 99.5 99.5

Spinning solution:
Concentration of PVA (*) (*) 17th 17th 17 17 17th 1000 18th 18th 17th added amount of boron
acid (%) (Ji) 2.0 2.2 2.2 2.2 2.2 2.6 2.6 2.0 pH 4.5 4.1 4.1 4.1 4.1 .4.0 ^] ■ 4.0 ³ L ■ * 2
4.5 * Coagulating bath:
NaOH (g / 1) 50 8th 110 80 15th 40 40 50 Na ₂ SO ₄ " 250 260 ISO 90 56Ο 220 220 250 Neutralizing bath:
H ₂ SO ₄ (g / 1)
Na ₂ SO ₄ " 70
500 70
500 70 not 70
spinnable
500 500 80
520 80
520 70
500 Stretching:
Total draw ratio 1500 1100 1200 1500 1200 1100 Roll drawing 100 bad
rolling
stretchable bad
crazy
able to bad 100
roller
stretched
bar 100 100

Table 2 continued

I.
(U pleasant Wet drawing in the
Heat (%) example 1 2 Comparative examples 5 6th 7th I.
ro W.
fan dinghy Dry stretching
in the warmth {%) 1 • χ ή. ' 150 140 150 - $ = ■ bellun 'th Amount of residual boric acid
(*)
Tenacity
(120 ⁰ C) (g / d) 150 220 192 l40 Hers CD
r; Initial module (120 ° C) (g / d) 220 0.51
6.2 0.52
7.0 0.15
7.3 1.00
7.0 0.46
6.5 own- O
co Creep (Creep X 135 ⁰ C) (Ji) 0.45
9.3 72 82 0.49
5.4 91 82 96 CX. QJ
U Plunger test (kg.cm) 135 2.5 2.2 63 2.3 2.4 2.3 CD
NJ d
ü High speed test
[(km / h), min.] 1.4 3524 4175 3.1 4632 4298 3485 OJ C.
φ Flexibility or edge strength
(kg / degree) 5863 184.10 192.25 2643 208.23 184.24 192.20 O
QO I.
C. shaft Tread or profile
strength (kg / mm) 217.20 31.9 32.8 160.40 30.7 32.5 33.4 cn
cc egg K! Durability {%) 40.5 7710 8290 30.2 8030 7960 8140 Ji fen 8 £ 20 73 76 7630 86 82 89 95 70

Table 2 continued

Comments: * 1

* 2

means that the pH has been adjusted with tartaric acid

means that the pH has been adjusted with acetic acid and sodium acetate.

In Example 1 to Comparative Examples, nitric acid was used to adjust the pH used.

Example 2:

PVA pastes containing sodium borate are produced according to the procedure described in Example 1, but 1.5 % sodium borate, based on PVA, is used instead of boric acid, and tartaric acid is used instead of nitric acid to adjust the pH. The fibers are drawn to a total draw ratio of 1500 % . The product obtained has a Garnzähfestigkeit of 9.1 g / d at 120 ⁰ C, a Garninitialmodul of 127 g / d at 120 ⁰ C and a Garnkriechen of 1.5% at 135 ° C.

In the manufacture of radial tires using the above yarn, the properties of tires become mutually exclusive compared, in which the twisting of the cord for the belt or breaker was changed as indicated in Table 3:

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Tabel

example
2 8th Comparative examples
9 10 11 73 18th 40 Twisting resp.
Twist number: 43.3 18th 40 Thread (ply)
(Turns / 10 cm) 30th 30th 23 Cable (turns /
10 centimeters) 30th 20th 11.5 Z Z Twisting resp.
Twist direction: S. S. thread Z Z Z 624 I386 cable S. S. S. Twisting resp.
. Twist constant of.
Thread 1039 1039 ' Γ97 100 100 Cable twisting or
-twist / thread thread- dito
12000
km no defects
after a
Run from
40000
km twisting.
. 100 {%) 100 67 50 96 no men
gel after
a run
from 40000
km the cord ditto
by doing
belt
broke after
a run
from 30,000 to 24,000
km km 45.6 30.6 Shelf life {% of
Residual strength of the
Cord according to εinem
Run of 20,000 km) 97 81 Walk or edge protection
stiffness (kg / degree) 40.3 39.6

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example J:

An aqueous solution of PVA in a concentration of 15% by weight , which contains 150 g of PVA with a degree of polymerization of 2350 and a saponification number of 99 # 5 mol #, is mixed with 30 g of boric acid (2% by weight , based on PVA) and a small amount of acetic acid are added to achieve a spinning solution of pH 4.5. The spinning solution is spun into a strongly alkaline coagulating bath, which consists essentially of water, which contains 40 g / l sodium hydroxide and 250 g / l sodium sulfate. The fibers are pulled out of the bath at a speed of 10 m / min, stretched to 100% by means of rollers, neutralized, hot-stretched wet to 150 %, to adjust the boric acid content to 0.4% by weight, based on PVA Rinsed with water, drained and dried, and finally hot-stretched to 200% dry. The product obtained (1200 d / 600 f) is then brought to a total draw ratio of 1400 % . The product thus obtained has a Garnzähfestigkeit of 9.2 g / d at 120 ⁰ C, a Garninitialmodul of L ^ lg / d at 120 ° C and a Garnkriechen of 1.9% at 135 ° C. It has excellent high temperature properties.

The yarn produced according to the above process is used to produce the belt or breaker of radial tires, by twisting it into a cord (1200 d / l / 3) under the following conditions:

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Thread twisting or twist Cable twisting or twisting

Direction of twist or twist:
Thread (ply)
Cable.

Twist constant of the thread

Cable twisting / thread twisting. 100

30 turns / 10 cm 30 turns / 10 cm

1039 100

No errors were observed after running 35,000 km. The fatigue strength was 98 % and the flexing or corner strength was 40.8 kg / degree.

Example 4 :

An aqueous solution with I7 wt .- # PVA containing 100 kg of PVA with a polymerization degree of I750 and 9 MoI Ji contains a saponification value of 99 * (2 wt to prepare a spinning solution with 2 kg of boric acid -.% _T based on PVA) and 0.3 kg of acetic acid (0.005 equivalent, based on 100 g of PVA). The pH is kept at 4.5.

The spinning solution is through nozzles with 1000 holes and

0.15 mm diameter spun into a coagulating bath containing 50 g / l sodium hydroxide and 200 g / l sodium sulfate. The fibers are pulled out of the bath at a speed of 10 m / min. The spinning behavior is very stable in this case. No difficulties arise during the two-week spinning, such as clogging of the nozzles, etc. The fibers obtained are then further processed in the same way as in Example 3. They are stretched on rollers, neutralized, wet-warm stretched, rinsed with water to bring the boric acid amount to 0.5 % By weight, based on PVA, to be adjusted, dehydrated, dried and hot-stretched dry. The product obtained in this way (1800 d / 1000 f) is brought to a total stretching ratio of 1400 % . It has a Garnzähfestigkeit of 9.3 g / d at 120 ⁰ C, a Garninitialmodul of ijk g / d at 120 ⁰ C and a Garnkriechen of 1.8% in

The yarn obtained in this way is used to manufacture the belt or breaker of a radial tire by placing it under twisted into a cord ÖL800 d / 1/2) under the following conditions:

Thread twisting Cable twisting Twist direction:

thread
cable

Twist constant of the thread

Cable twisting / thread twisting. 100 {%)

30 turns / 10 cm 30 turns / 10 cm

1272

100

209823/0869

No errors were found after running 35,000 km. The fatigue strength is 96 % and the flexing strength or corner strength is 41.2 kg / degree.

2Ü823 / 0 8 69

Claims (3)

Claims:. '«Cfiigta ,,:, ftrrf i 1. ί polyvinyl alcohol fibers having excellent high temperature performance, characterized by a Garnzähfestigkeit of about 7.5 g / d at 120 ⁰ C, a Garninitialmodul of about 100 g / d at 120 ⁰ C and a Garnkriechen of below 2% at 155 ° C, the have a boric acid or borate content of 0.2 to 0.9 wt .- #, based on polyvinyl alcohol. 2. Polyvinyl alcohol fibers according to claim 1, characterized in that a boric acid or borate-containing spinning solution of polyvinyl alcohol at a pH between 3 and 5 is spun into an aqueous solution containing 10-100 g / l alkali metal hydroxide and 100-330 g / l sodium sulfate , stretching the threads obtained by means of rollers, neutralizing them, stretching them while hot, adjusting the amount of boric acid or borate by rinsing with water to 0.2 to 0.9% by weight , based on polyvinyl alcohol, dewatering the threads, drying them and finally stretching them dry and heat-drawing to a total stretching ratio of over I300 %, 3. Radial tire whose belt or breaker consists of a cord which contains the polyvinyl alcohol fibers mentioned in claim 1, whose twist constant for the thread (ply) is 800-1300 and whose twist for the cable (turns / 10 cm) 80-100 % of the thread twist (turns / 10 cm). 2098 * 3/0869 Pi - Sl K, radial tire according to claim 3, characterized in that the polyvinyl alcohol synthetic fibers obtained according to claim 2 are used to produce the cord for the belt or breaker.