NO138622B - DEVICE IN THE AIR PIPES FROM OIL TANKS ON SHIPS - Google Patents

Description

Process for the polymerization of ethylenically unsaturated monomers.

The present invention relates to a

method for the polymerization of certain

ethylenically unsaturated monomers.

So far, polymerization of larger ;

amounts of ethylene-unsaturated monomeric material which is at least partially not

miscible with water, in practice has been limited to the use of in the monomers

soluble catalysts such as organic ones

peroxides. Aqueous hydrogen peroxide has

not been considered applicable in such po-

lymerizations, as it is poorly soluble in monomers that are not miscible with water.

Among other things for these reasons have

the use of hydrogen peroxide as a catalyst has practically been limited to emulsifiers

tion polymerization in an aqueous environment of such

monomeric materials, in the form of activated

systems or redox systems, which generally lead to products of relatively

high molecular weight.

When in monomeric soluble organics

peroxides and organic hydroperoxides

are used as catalysts for mass polymerization of diene monomers, they show a

tendency, especially at higher temperatures, to cause discoloration and odor

which is difficult to remove in the polymers

products.

In addition, there are disadvantages in that the rate of polymerization in mass polymerization using organic

peroxides and organic hydroperoxides are

difficult to regulate, especially at higher temperatures, and because there is a tendency for

early gel formation, as well as formation of be-

put on the reactors when the polymers are produced from conjugated dienes.

In other embodiments of mass polymerization using alkali metals, alkaline earth metals, alfin and Frie-del-Crafts catalysts, there is a tendency to form polymers with one or more characteristics for such polymerizations, such as: polymers containing ca - catalyst residues or odorous substances which are difficult to remove, polymers containing isomerization products or unwanted end groups, polymers with undesirable molecular weight, and — in the case of polymers from the complete or partial polymerization of conjugated diene monomers — an undesirable predominance of 1,2-configuration, and thus an unfavorable amount of side groups.

Such disadvantages are remedied by the method according to the invention.

In this method, monomers are polymerized which do not dissolve more than 3.5% by weight. water at 20°C and comprising vinylidene monomers, vinyl monomers or monomers with several ethylene double bonds using catalysts essentially consisting of aqueous hydrogen peroxide which preferably contains between 48 and 54 wt. H202, and while carrying out the polymerization at a temperature of at least 100°C, preferably between 110 and 150°C, and the main characteristic feature of the invention is that the polymerization is carried out in the presence of a common solvent for both the monomers and the aqueous hydrogen peroxide , and which essentially consist of water-soluble ketones, alcohols or ethers, or azeotropic boiling mixtures of alcohols or ketones and liquid hydrocarbons, whereby a homogeneous, liquid phase is maintained between the monomers and the aqueous hydrogen peroxide.

The term "common solvent" means a solvent or a mixture of solvents which serves to form a liquid single-phase system of the monomer and the aqueous hydrogen peroxide.

By proceeding according to the invention, the following advantages are achieved: 1. Low molecular weight polymers can be obtained, especially polymers with an average molecular weight in the range of 500 to 10,000. 2. The formation of crosslinks in the polymer is reduced, and consequently reduced

the tendency to gelation.

3. Discolouration, odor and other undesirable effects caused by organic peroxides are avoided. 4. The polymerization can generally be easily regulated.

The method according to the invention can be used with particular advantage in the polymerization of monomers which do not dissolve more than 1 percent of water at 20°C. Examples of monomers to which the invention can be applied are conjugated diene monomers such as butadiene-1,3; 2-chlorobutadiene-1,3; isoprene, piperylene and hexadienes, vinyl monomers such as styrene, α-methylstyrene, di-vinylbenzene, vinyl chloride, vinyl acetate, methyl methacrylate as well as ethyl and methyl acrylate, trialkyl cyanurate, phenylmaleic acid and acrylonitrile.

The method according to the invention is particularly advantageous for the production of low-molecular, generally liquid, polymers of conjugated dienes and low-molecular, generally liquid, copolymers or mixed polymers of dienevinylidene monomers. The latter copolymers or mixed polymers are often advantageous as resin and binder components in the production of decorative and protective coatings.

In the method according to the present invention, the catalyst essentially consists of hydrogen peroxide, and the method must therefore be distinguished from polymerization processes where hydrogen peroxide is used in the presence of a redox system.

The polymerization can be regulated by adjusting the polymerization conditions, in particular the temperature and the hydrogen peroxide concentration. The optimum conditions for a particular polymerization will depend on the monomer material being polymerized and the nature of the polymer or copolymer being formed. In general, it has been found to be preferable to work at temperatures between 100 and 200°C, preferably between 110 and 150°C.

The percentage by weight of hydrogen peroxide in the aqueous hydrogen peroxide solution should preferably be greater than 33 and less than 80. In amounts below 33 percent by weight, hydrogen peroxide generally tends to act too slowly as a polymerization catalyst, and in amounts above 80 percent by weight the risk of explosion becomes too great. The best results are generally obtained by using 48 to 54 percent by weight of hydrogen peroxide. When carrying out the method according to the invention, care must be taken to avoid that hydrogen peroxide and organic material are at any time present in explosive conditions. If, for example, the aqueous hydrogen peroxide used contains more than 80% by weight hydrogen peroxide, a common solvent and diluent equivalent to two or three times the volume of the aqueous hydrogen peroxide must be added before the monomer is added. Similar precautions must be taken when the concentration of hydrogen peroxide in the aqueous solution is between 54 and 80 percent by weight, although the volume of the joint solvent and diluent need not be so large. When the concentration of hydrogen peroxide in the aqueous solution is below 54% by weight, it is of no importance in which order the components are added, except that a homogeneous solution or one phase must be obtained before the mixture's temperatures are raised to within the polymerization range for the monomeric material in question. The polymerization can be initiated by adding all the required hydrogen peroxide, or only part of it, while the rest is added during the reaction.

It is preferable to use a volume of common solvent at least as large as the volume of the aqueous hydrogen peroxide.

The common solvents for use in the present method are those which form single-phase systems in all mixing ratios, both with aqueous hydrogen peroxide and with the relevant monomeric material. Such solutions include those alcohols, ketones, ethers, alcohol ketones, alcohol alcohol ethers and alcohol esters which are miscible with water in all proportions and which do not contain unsaturated, polymerizable carbon-carbon-carbon bonds. Examples of such solvents are methanol, ethanol, n-propanol, isopropanol, acetone, methylethyl ketone, dimethyloxyethane, methylcellosolv, and dioxane.

The common solvent can also be a mixture of two or more solvents, one of which in and of itself need not dissolve one of the reactants. Thus, azeotropic mixtures of different solvents have in many cases proven to be particularly suitable, as recovery of the liquid medium is thereby facilitated. Such azeotropic boiling mixtures include mixtures of a hydrocarbon diluent, e.g. toluene, and a C 1 to C 4 alcohol, e.g. isopropanol; and mixtures of an alcohol and a ketone, e.g. methanol and acetone.

Many of the solvents which are used as common solvents are normally quickly oxidized by aqueous hydrogen peroxide at the temperatures at which the polymerization is carried out. In the presence of the monomeric material, however, it has been shown that polymerization generally takes place rather than oxidation, and the latter becomes of secondary importance.

The weight of hydrogen peroxide as H202 per 100 g of monomer can conveniently lie between 0.5 and 10 g, preferably between 1.0 and 5 g, and most preferably between 2.0 and 4 g.

Antioxidants may be present in the monomeric material to be polymerized, and thus it may be unnecessary to remove an antioxidant present in the starting material.

The structure and/or molecular weight of the final polymer formed in a given case can be regulated, among other things, by varying the polymerization temperature, by varying the volume and concentration of the aqueous hydrogen peroxide, and by adding a modifying or chain transfer agent. Among the modifiers and chain transfer agents that can be used are the mercaptans including the Ct to C1R alkyl mercaptans, e.g. isopropyl mercaptan, butyl mercaptan, amyl mercaptan, hexyl mercaptans, n-dodecyl mercaptan and tert.dodecyl mercaptan, mercaptoalcohols, e.g. mercaptoethanol, aryl mercaptans, e.g. thio-p-naphthol, thiophenol, organic sulphides and disulphides, e.g. diethylsulfide, diphenylsulfide and diphenyldisulfide, thioacids, thioesters and other sulfur compounds, e.g. ethylthioglycolate, diethyldithioglycolate, diisopropyl dixanthogen, halogenated compounds with 1 to 18 carbon atoms, e.g. carbon tetrachloride, chloroform, butyl chloride, n-amyl chloride, methyl chloroform, alkyl chloride, chlorobenzene, bromobenzene and propylene chloride, hydrocarbons such as methane, ethane, methylcyclohexane, benzene, toluene and ethylbenzene, water-insoluble alcohols, ketones, ethers, esters and carboxylic acids with 5 to 18 carbon atoms, e.g. cyclohexanol, n-hexa-nol, iso-octanol, diamyl ketone, dioctyl-heptane, hexyloctyl ketone, dibutyl ether, di-hexyl ether, methyl hexanoate, amyl butyrate, lauric, oleic acid and stearic acid. As it appears here, many substances that can act as modifiers or chain transfer agents can also act as or form part of the common solvent, and thus the latter can serve the purpose of both maintaining a homogeneous liquid environment and modifying the polymerization.

During the execution of the present method, the presence of oxygen should preferably be avoided, as it can lead to polymer gelation. A source of oxygen is the catalytic decomposition of hydrogen peroxide. This decomposition can be minimized by building the reactor system for use in the present method from materials that do not significantly catalyze the decomposition of hydrogen peroxide, such as glass, ceramic material, tin, aluminum or stainless steel. Thus, the inner surface of the reaction vessel should be constructed of or coated with aluminum, an aluminum alloy, tin, stainless steel, glass, enamel, porcelain, or a resin or other material in contact with which hydrogen peroxide is relatively stable.

The decomposition of hydrogen peroxide can be further prevented by the addition of smaller amounts of one or more hydrogen peroxide stabilizers. Such stabilizers are well known, and preferred stabilizers include inorganic boron compounds, e.g. boric acid. The hydrogen peroxide stabilizer or stabilizers can be added to the feed streams of the reactor systems, added separately, or added during the reaction. The amount of stabilizer should be less than 0.1 per cent based on the feed, preferably between 5 and 500 parts per million based on birth.

If an excessively large amount of inhibitor is added, it may be necessary to remove this from the polymeric product.

The reactor can be of any suitable type, but preferably a tube reactor, or a reactor of the tank type, with or without tubes. The polymerization can be carried out batchwise, continuously or periodically. With continuous polymerization, a smoother product is formed than with batch polymerization. In the continuous process, the reactants are fed to the reactor at a constant rate, and the polymeric product can be removed continuously so that the volume in the reactor is kept constant, and a constant degree of polymerization is achieved. In the case where the reactants contain two monomers with widely different copolymerization rates, such as isobutylene and acrylic esters, the polymerization can be initiated by hydrogen peroxide with only acrylic ester present, and after the start period is over, the less easily polymerizable isobutylene is added.

The polymerization process according to the present invention is carried out with or without a steam room, depending on whether the reactions are carried out batchwise or continuously. At the polymerization temperature, the reaction vessel can be exposed to considerable pressure, e.g. 28 to 35 kg/cm2 by polymerization of butadiene-1,3. For other more volatile materials, the pressure can be several hundred kg/cm2. As all these polymerization reactions are exothermic, it is important for the chosen reaction systems to ensure sufficient heat transfer to prevent the reactions from running rampant. The polymerization time will depend on the materials and temperatures used, and can extend from about half an hour to four hours or more, usually a time from 1 to 3 hours will be sufficient to achieve a favorable conversion of the monomers by their optimum polymerization temperature.

The formed polymers can be purified by the normal methods, such as steam stripping and vacuum heating.

The invention is illustrated by the following examples:

Example 1.

To 4 glass bottles, each containing the same amount of hydrogen peroxide in different amounts of water, 45 ml of isopropanol (the common solvent which in this and the following examples is abbreviated to M-S) and 25 g of butadiene-1,3 were added. The bottles were corked and placed in a vapor pressure chamber for 3 hours at 100°C. After cooling, the bottles were opened and the volatile impurities present, mainly butadiene-1,3-, butadiene dimer, isopropanol, acetone, residual hydrogen peroxide and water, were driven off the polybutadiene by vacuum heating. The resulting products were clear, colorless, viscous, liquid polybutadienes. Data for the four experiments in this example are given in Table I.

Example 2.

The ingredients were mixed, and the product purified in the same way as in the example

1, the practical details of the two trials were as indicated in table II. Clear, colorless, viscous, liquid polybutadienes were obtained.

Example 3.

The practical details of this example are given in Table III. The components

were mixed, and the polymer purified in the same manner as in Example 1.

Example 4.

The ingredients in this example were mixed and the product purified in the same way as in example 1. The practical details are given in Table IV. This example compares the effect of various esters and ketones with the effect of a typical C, to C4 alcohol, isopropanol, as a common solvent.

Example 5.

This example shows the effect of different common solvents in the polymerization of isoprene. Practical details are given in table V. The mixing of the components and the purification of the products were carried out as in example 1. Piperyl can be used instead of isoprene, and if the polymerization time is made three times as long as for isoprene, comparable yields are obtained.

Example 6.

The ingredients were mixed and the resulting polymers purified in the same manner as

in Example 1. Table VI gives the practical details of the polymerization of various vinyl monomers and cyclic diene monomers carried out in this example.

Example 7.

In this example, the various monomers were simultaneously added to the aqueous hydrogen peroxide-isopropanol mixture. If, however, a shiny clear mixed polymer is required, the polymerization of the butadiene is first initiated, with or without traces of other monomers, after which the styrene is added, and the polymerization continues. The practical details of this example are given in Table VII.

Example 8.

The components were mixed as in example 7, and the polymeric products purified

as in example 1. The practical details are given in table VIII.

Example 9.

The ingredients were mixed as in Example 7, and the products purified as in Example 1. The practical details of this example are given in Table IX.

While most polymers formed by the process according to the present invention are water-clear, these mixed polymers based on amine monomers are occasionally somewhat amber in color.

Example 10.

In this example, the ingredients were mixed as in example 7, and the products I

purified as in Example 1. The practical details are given in Table X.

Example 11.

In this example, azeotropic mixtures were used as the common solvent

share. The ingredients were mixed and the products purified as in Example 1. Table XI indicates the practical details and the yields achieved.

Example 12.

This example illustrates the different conditions required for the formation of polymers of different molecular weight. The practical details are given in Table XII. The components were mixed and the products purified in the same way as in example 1. Experiment 73 gave a polybutadiene typical of the polymers formed from hydrocarbon-conjugated dienes by the method according to the present invention. Infrared spectrum for this polybutadiene shows a structure dominated by 1,4-configuration (about 75 per cent), which in turn is dominated by trans 1,4-configuration (about 85 per cent trans), while only the smaller remaining part consists of cis 1,4 configuration.

Likewise, the infrared spectrum of the liquid copolymer in test 72 showed the same predominant amount of trans 1,4 configuration for the diene-derivatized portion of the blend polymer.

Example 13.

Continuous polymerization was carried out in a cylindrical high pressure tube of 3 inch internal diameter and 10 feet length, provided with a cooling jacket. Hot water of approximately 113°C was circulated through the jacket under pressure in an amount of approx. 225 liters per minute. This maintained a polymerization temperature in the middle of the tube of approximately 115°C. The reactants were pumped into one end of the tube with a high-pressure displacement pump, and the product withdrawn at the other end of the tube through a relief valve set at 35 kg/cm2. The charge was prepared as follows: for every 1400 g of isopropanol, 226 ml of a 50% by weight aqueous peroxide was added, followed by 4000 g of butadiene-1,3. In this example, butadiene-1,3 was distilled to remove inhibitor (although such distillation is not necessary). The resulting homogeneous solution or single phase was cooled and pumped to the reactor in an amount of 870 ml per hour. The reactor effluent was first stripped of butadiene, then isopropanol and small amounts of acetone formed during the reaction, and finally vacuum and steam stripped to remove butadiene dimer, water

and traces of hydrogen peroxide. A try on

3193 g of the reactor effluent yielded 1026 g of polymer,

which represented 45 percent butadiene conversion. The polymer was a water-clear, viscous

liquid with a Gardner viscosity of between z-5 and z-6.

Claims (1)

Process for polymerization of monomers that do not dissolve more than 3.5% by weight. water at 20°C and comprising vinylidene monomers, vinyl monomers or monomers with several ethylene double bonds using catalysts essentially consisting of aqueous hydrogen peroxide which preferably contains between 48 and 54 wt. H202, and while carrying out the polymerization at a temperature of at least 100°C, preferably between 110 and 150°C, characterized in that the polymerization is carried out in the presence of a common solvent for both the monomers and the aqueous hydrogen peroxide, and as in the essentially consist of water-soluble ketones, alcohols or ethers, or azeotropically boiling mixtures of alcohols or ketones and liquid hydrocarbons, whereby a homogeneous, liquid phase is maintained between the monomers and the aqueous hydrogen peroxide.