DE2353167A1 - FLAME RETARDED BROMED LATEX - Google Patents

Description

The present invention relates to a method for Manufacture of flame retarded tatices by direct bromination .of latices from vinylaryl monamers and conjugated diolefins.

The use of styrene-butadiene-latex as the backing material for textile carpet is known. The latex itself burns because of it not easy due to its high water content. After application on The resulting polymer film is the carpet and water drainage however, due to the thin cross-section of the product

susceptible to burning besoriders. -

These latices are made by adding various bromine-containing ", Low molecular weight compounds, such as organic phosphates, made something self-extinguishing. For certain tep-

("tufted") however, such as "tufted and non-woven carpets, have the necessary to effectively delay a burning, high amounts of additive have an adverse effect on the other Polymer properties. ·

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It is known that brominated styrene / butadiene copolymers can be used by direct bromination of the copolymers with molecular bromine. Attempts to burnish styrene / butadiene latices however, with molecular bromine have resulted in coagulation of the latex due to the high acidity of the system.

It is also known to brominate styrene / butadiene latices by adding bromine water. Because of the low solubility of the bromine in water (2-4% by weight), the use of bromine water results in an extremely strong dilution of the latex, which makes the subsequent use of the latex uneconomical. This method is thus limited to introducing low levels of bromine (less than 5 %) into the latex.

A new, effective process has now been found for brominating uinylaryl monomers / conjugated diαlefin latices without coagulation or undesired dilution of the latex. The process is characterized in that an emulsion of bromine in water is added to the latex at such a rate that the bromine color disappears as quickly as it is formed. The bromine emulsion comprises 20-30% by weight of bromine, which is emulsified in the water with the aid of a suitable surface-active system. In the novel process, flanmverzögerte latices having a bromine content up to 40 wt - prepared.%.

The inventive method is based on the bromination of many different, rubber-like polymers that can form stable latices, applicable.

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A simple addition of Bromine to the remaining 'unsaturated' bonds of the latex polymer. The process according to the invention is therefore suitable for the bromination of all available rubber polymers with the rest

unsaturated bonds due to polymerization or interpolymerization conjugated diolefins, such as 1,3-butadiene, 2,3-dimethyl- 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2-chloro-i, 3-butadiene (Chloroprene), piperyleri, etc.

The latex polymers can be copolymers of the above conjugated Be diolefins with vinyl aryl monomers. Suitable vinyl. arylamonomere are styrene, substituted styrenes such as methylstyrene, Dimethylstyrene, ethylstyrene, chlorostyrene, dichlorostyrenes, p-isopropylstyrene, p-tert-butylstyrene, divinylbenzene, vinylnaph- ■ thalin usiu. or mixtures of these monomers.

The preferred mixed polymer latices of vinyl aryl monomers and conjugated diolefins contain 20-70 % vinyl aryl monomer and 30-80 % conjugated diolefin. Certain latex polymers suitable as carpet backing material can also contain up to 10% of one or more additional monomers such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, aconitic acid, acrylamide, methacrylamide, itaconamide, Diacetone acrylamide usiu., Contain. ;

The initial latex should have a solids content between ... 45-60%. The latices with a higher solids content are preferred because of the inevitable dilution which anoints with the emulsions according to the invention with a relatively high bromine content

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entry.

The bromine emulsion is made by adding bromine to water, which is a suitable Contains emulsifier system. The bromine u / earth the aqueous - solution of the surfactants under mechanical Stir added to disperse the bromine. The final emulsion is light brown in color. Although the emulsion is very stable should ensure complete emulsification Continue stirring and grounding until the bromine is added to the latex to be brominated. The bromine emulsion should be used for every be freshly prepared due to possible hydrolysis of the bromine in the aqueous medium.

Particularly suitable surfactants for preparing the bromine emulsion are the commercially available anionic surfactants such as alkylarylsulfonates, organic phosphate esters, sulfated esters of fatty acids, sodium dodecyldiphenylether disulfonates, dialkyl esters of succinic acid and sodium dialkylsulfosuccinates. The anionic surface active agents are used in amounts of 2-4 wt -% of the used emulsion.. Greater than 4 % surfactant can be used; however, the amount of the surface active agent becomes appropriate. "Keeping the bromination of latices to a minimum in order to keep the total amount of surfactants in the latex to a minimum.

Nonionic surfactants can be effective in stabilizing the emulsions when used in concentrations above 4% by weight, but have been found to be ineffective at 3% concentration.

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The bromination of the latex is a quick reaction and takes place at room temperature by adding the bromine emulsion to the latex with stirring and at such a speed * that the bromine color disappears between each encore. The pH of the latex falls drastically during the addition of bromine, and you have to use a base, such as Ammonia, sodium hydroxide, potassium hydroxide, morpholine, water-soluble Add amines, hydroxyamines, etc. to adjust the pH of the latex to 7-10. '..---

According to the process according to the invention, latices with up to about 40 % bromine have been produced. Attempts to introduce greater than 40 % bromine have usually been unsuccessful due to the coagulation of the latex. At higher B'rom concentrations, such as. 25-40 %, it is advisable to add a buffer salt _r such as diammonium phosphate to the latex to help prevent coagulation due to the low pH value. Latices with higher percentages of bromine have been found to have a low percentage solids content for a commercial use. Excess water can be removed from them using standard procedures. ■

The following examples illustrate the present invention, without restricting them.

Example ■ 1 —-

Preparation of the bromine emulsion -

In a glass-lined one equipped with an effective stirrer Reactor were 80 parts of water with 2.2 parts of sodium dodecylbenzenesulfonate and 0.8 part of sodium dihexylsulfur succinate introduced as emulsifiers. The stirrer was turned on and there

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26 parts of bromine were added. The mixture was stirred to disperse the bromine and form an emulsion having a density of 1.2 g / cc and a bromine content of 23.8 % by weight. The bromine emulsion was continuously stirred until it was used in the subsequent bromination, although it is stable for about 30 minutes without stirring. Since the emulsion is subject to hydrolysis of the bromine in the aqueous medium, only the

amount of emulsion used in a day. Bromination of styrene / butadiene latex

A 100 g latex sample made from a copolymer of styrene, butadiene and acrylic acid (59.4-39.6-1.0) with a solids content of 52.5 % and a pH of 3.0 was put into one of each 6 reactors lined with glass. The bromine emulsion prepared above was added to each reactor at the rate of the bromine reaction indicated by the disappearance of the bromine color. The amount of bromine emulsion added to each reactor was calculated from the amount of bromine desired in the polymer, assuming quantitative bromination. The latices obtained were neutralized with ammonia and stored for one month to determine the stability of the latex and the change in pH. The results are shown in Table 1. Experiments 5 and 6 with the higher bromine content were buffered with about 2 % diammonium phosphate to prevent coagulation due to the pH value.

4/0660

Attempt no.

Köntr.

/ ο bromine in the polymer

calculated --

analyzed

^ y solids content \ 52.5

Latex stability; Months A pH of the latex

initially 3.0

after 1 week, 3.2

after 2 weeks 3 »O

after 4 weeks 3 ^ 1

* - buffered

Tabel· 2 1 4th 5 6th 1 9.5
9.7 3 17.5:
17.0 23.2
21.0 36.3
32.5 5.3 ■.
6.8 47 13.5 ·.
13.3 44 ■ 42 36 49 ¹ 45.4 .etum 1 1 ·. , 1 1 .·' 8.0
6.5 ,, ^. . ■
6.7
6.3 1 7.0
5.75
5.6
5.0 8.25 *
7.8
7.35
7.0. 8.25 *
- 8.15
7.7
7.25 6.5
5.2
5.1
4.8- 7.0
5.8
5.3
5.15

It is noteworthy that after one month only the latex from Trial 4 coagulated despite a drop in the pH of all of the latexes. Although the addition of the bromine emulsion diluted the latices to some extent, the percent solids content after the bromination could be increased to that of the original latex by possibly stripping off the excess water. It is important to note that if a 2% bromine solution (e.g. bromine water) was used, the volume of water used to produce the latex containing 32.5% bromine in Experiment 6 would be extremely large, so that the solids content was reduced to about 6 %.

would have decreased instead of the 36 % received.

example 2

The bromination process of Example 1 was repeated to produce a brominated latex based on a copolymer of 61 % styrofoam], 39 % butadiene and 1 % itaconic acid. The starting latex contained such an amount of a known flame retardant additive that a control sample containing 1.1 % bromine resulted. The latices obtained were all diluted to a solids content of 43% and then applied to cotton fabric to determine the polymer bond strength. This test was carried out by measuring the maximum force required to separate two pieces of cotton fabric which had been impregnated with the latex, pressed together and cured for 10 minutes at 132 ° C. in a drying oven. This test is of practical value in determining how good a latex is for gluing light cotton fabrics. The limiting oxygen index (LOI) was also determined for each latex polymer. The LOI χ 100 is the one in one

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Oxygen-nitrogen mixture required percentage Oxygen to make a sample burn. The greater the LOI, the more The preparation is more flame retardant. The results are in Table 2 listed.

Tabe lle 2

Test% bromine in the LOI bond strength l \ lr . Polymer -: -. _ Ka

1.1 (added) 0.185 4.1

control 1.1 Baisp. 2-1 5.5 2-2 8.8 2-3 15.3: 2-4 19.9 2-5 27.8

0.195 3.9 0.202 3.2 0.225 2.9 0.242 " 2.5 0.279 1.8

As can be seen, the bond strength decreases with increased amounts of bromine strong in the polymer. This property must be weighed against or compensated for against the improved flame retardancy measured by the LDI values.

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Claims (1)

Claims 1.- Process for the production of a self-extinguishing polymer preparation in latex form, characterized in that one a) an emulsion of 20-30 wt .- ^ bromine in water with stabilization forming the emulsion by means of an anionic surfactant system; b) the bromine emulsion to form a polymer latex at such a rate adds that the bromine is almost completely consumed by the polymer latex - and the desired Degree of bromination has occurred, with as a polymer a copolymer of conjugated diolefins and vinyl aryl monomers is used; and c) the latex to increase the pH fourth to 7.0-9.5 a beisc inflicts. 2, - l / experienced according to claim 1, characterized in that a copolymer of 20-70 Gem .- ^ styrene and 30-80 Gb \ u .-% butadiene is used as the polymer latex. 3, - l / experienced according to claim 1 and 2, characterized in that that the bromine emulsion is added until the latex 7-40 wt .- ^ Bromine, based on the percentage of solids in the latex, contains. . - 4, - A method according to claim 1 to 3, characterized in that the anionic surfactant system comprises a mixture of 2-2.5 wt -% sodium dodecylbenzenesulfonate and 0.5-1.0 wt .-): i comprises sodium dihexyl sulfosuccinate and as the base. Ammonium hydroxide is used. The patent attorney: 409824/0680;