DE2023999A1 - Encapsulated monomeric product and process for making the same - Google Patents

Description

Encapsulated monomeric product and process for making the same

Encapsulation methods (in which a core is made of a substance in general of a liquid, in a layer of a normally solid second fabric is wrapped) in the chemical technology is becoming increasingly important. These methods have the difficulty of dealing with many sticky, corrosive or extremely reactive substances and, more importantly, it opens up a way in which normally liquids are put to uses which previously normally required solid substances was. Typical examples of liquids known to be encapsulatable are inks, adhesives, pharmaceuticals Agents and oils.

A wide variety of materials are already available for encapsulation used. The most famous of them are hydrophilic colloids,

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which are deposited on the surface of the liquid; _{See USA Patent 2,800,457} .. More recently, petroleum-based polymers have been used to form encapsulating ΑΑ ι * .ι.χοΐι by bringing small particles of the core material into contact with copolymerizable reactants. Under polymerization conditions, the reactants then polymerize on the surface of the core material and form an encapsulating shell; See U.S. Patents 3,219,476 and 3,270,100.

Recently there has been an increasing * interest in encapsulation polymerizable substances j, especially in the separate encapsulation of copolymerizable reactants. In this way, two substances can be linked mix without having to fear premature implementation. For example, you have an epoxy monomer and a Specific hardening agent encapsulated separately in mixed polymer shells and the encapsulated particles together mixed and stored together. When using such mixtures, the capsules are exposed to heat or mechanical force broken, and the epoxy compound is cured to an epoxy resin in the conventional way »· ·

For many purposes, however, it is undesirable to use polymeric To encapsulate substances in a foreign substance shell, i.e. in a shell, which consists of a different polymer than "that which forms during the polymerization of the core substance. This is especially true when it comes to monomers used as adhesives or adhesive-type sealants should be used. In many cases, foreign substances impair the strength or the connection between the the polymer and the adjacent surfaces. This is especially true for homopolymers, i.e. for polymers, which result from successive reactions between a Form monomers and other molecules of the same monomer. Using any second respondent to

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to create a skin on a core made of such a material, becomes an undesirable foreign substance in the monomer ■ Material introduced. There is therefore a need for encapsulated homopolymerizable monomers in which the Capsule shell consists of the homopolymer itself. There is also a need for a method of making a such product.

It has been found that encapsulated, homopolymerizable substances can be produced according to the invention. The product according to the invention is an encapsulated homopolymerizable material, which consists of "a core made of a liquid a monomeric material and a shell surrounding the core made of a homopolymer of the same monomer. Encapsulated products of this type can be produced by adding individual amounts of one introduces homopolymerizable monomeric material into a fluid, brings the individual amounts therein into contact with a polymerization catalyst which is able to catalyze the homopolymerization of the monomer, and removes the individual amounts from the fluid as soon as the encapsulating homopolymer shells have formed Monomers that are encapsulated in a shell made of homopolymer, which was formed on the spot from the monomer. '

These encapsulated products are unique in a number of ways. They are composed of a single component encapsulated products, d, _e li a polymerizable monomeric material in an envelope of its own homopolymer. When used as an adhesive or sealant, no diluent is present & _{f that could} affect the strength or continuity of the bond formed between the adhesive and the bonded surfaces.

The method described above also offers a number of advantages over the previously known encapsulation methods.

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It represents a method of manufacturing the encapsulated product described above, consisting of only one component. In this process, no separate encapsulating agent needs to be used, since the shell is formed from the core material itself. The only component that continuously supplied v / ground must .is the monomeric material _o In forming the capsule shell is hardly polymerization = catalyst consumed "add one braucht'nur from time to time small amounts of catalyst to the low Verluste_ or low consumption to replace the catalyst »

According to the invention, all monomers which can be homopolymerized under the action of a polymerization catalyst can be used as polymerizable monomeric substances. As "polymerization" materials are referred to herein including, but not participate much in the polymerization, either excite the homopolymerization of the monomer or the extremely low rate of Homopolyaerisation of monomers, "ζ, B ₀ by several orders of magnitude increase ,,. In both cases the result is the initiation of dex * homopolymerization of a monomeric material that is inherently _{stable over long periods of time, Z 0} B ₀ several months or longer.

The term "monomeric material" refers not only to a single monomer in a pure or impure state, but also to individual monomers in a mixture with one or more non-polymerizable, functional constituents ₉ Wi =? ataMlizers and polymerization accelerators, as well as mixtures of related monomers, which react under the influence of a polymerization catalyst to form a single type of pclivii isrisate.

lr> acquisitions of the invention may Although a variety of mono »Ί3ΐ; βίΐ Souff © be used ^ particularly suitable have Tit;, -isdöoh liquid <polymerizable absence of air: -; proven 23'bsto.ffe lind Diolitungsmittel (the?.? hereinafter ge =

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collectively referred to as "anaerobic adhesives"). Anaerobic Adhesives are made from polymerizable monomeric acrylic acid esters and peroxy polymerization agents. In the presence of air or oxygen, they "remain stable; as soon as however, in the absence of air or oxygen, they polymerize into hard, durable resins. Derar »· Term adhesives are particularly suitable for bonding Metals and other non-porous or air-impermeable materials that allow air and oxygen to enter the adhesive prevent the adhesive from polymerizing and the top. binds surfaces together. Polymerizable di- and other polyacrylic acid esters are particularly valuable as adhesive monomers, because they have the ability to make crosslinked polymers form, and therefore represent very advantageous adhesives. But you can also use monoacrylic acid esters, especially if the part of the ester that does not consist of the acrylate radical has a hydroxyl or amino group or another reactive group Contains substituents that can serve as a crosslinking point. Examples of monomers of this type are methacrylic acid hydroxyethyl ester, Acrylic acid cyanoethyl ester, methacrylic acid tert-butylaminoethyl ester and glycidyl methacrylate. The monomeric acrylic acid esters have anaerobic properties bestowed by treating them with a peroxy polymerization agent mixed.

One of the particularly preferred groups of polyacrylic acid esters, which can be used as adhesives are polyacrylic acid esters of the general formula

H ₅ C = CCO

'2

R.

R ¹
-CO

0 -C-C = CH,

in which R is a hydrogen atom, an alkyl or hydroxyalkyl radical having 1 to 4 carbon atoms or a remainder of the composition

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-CH ₀ -OCC = GH ₉ '2

ir · »

R represents a hydrogen or halogen atom or an alkyl radical

1 to 4 carbon atoms, Br is a hydrogen atom, a hydroxyl group or a remainder of the composition

-0-C-CsOH ₂ E ²

la is an integer of at least 1, "z _o B _e from 1 to about 15 or more and preferably from 1 to about 8, η an integer of at least 1, ZeH" from 1 to about 20 or more, and ρ denotes Value 0 or 1 has _o

Examples of employable in the invention, polymerizable polyacrylate esters of the above general lormel are Di =, tri- and tetraethylene glycol dimethacrylate, Dipropylenglykoldi- 'methacrylate, Polyätüylenglykoldiinetnacrylat, di- (pentamethylene glycol) -dimetliäcrylat, ietraäthylenglykoldiacrylatj · Tetraäthjlenglykoldi-Cchloracrylat), diglycerol diacrylate, Diglycerintstramethacrylat, tetramethylene dimethacrylate, ethylene dimethacrylate, Neopentyl glycol diacrylate and erimethylol propane triolate. These monomers do not need to be in the pure state, but can be technical mixtures which additionally contain inhibitors or stabilizers such as polyhydric phenols, quinones, etc. The term "polymerizable monomeric acrylic acid esters" includes not only the above monomers in the pure and impure state, but also other mixtures which contain these monomers in sufficient quantities to give them the characteristic polymerizability of the polyacrylic acid esters. It is also within the scope of the invention, the characteristic properties of the cured resins by using monomers of the above general Pormel together with other unsaturated monomers ₉ such as unsaturated hydrocarbons or unsaturated esters, to "be influence on _o

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The "preferred peroxy pathogens, which together with the above 1) 0-, polymerizable acrylic or polyaoryl acid esters can be used, 'are the hydroperoxy polymerization pathogens, and in particular the organic hydroperoxides of the general formula R OOH, in which R is a hydrocarbon radical with up to about 18 carbon atoms, preferably an alkyl, aryl or aralkyl radical with 1 to about 12 Carbon atoms, means. Typical examples of such Hydroperoxides are cumene hydroperoxide, methyl ethyl ketone hydroper oxide and hydroperoxides, which are formed by the addition of oxygen to various hydrocarbons such as methylbutene, Done and Cyclohexene. However, other peroxy pathogens can also be such as hydrogen peroxide or certain organic peroxides or peresters that are produced by hydrolysis or decomposition in Skip hydroperoxides.

The proportion of peroxy pathogens commonly used is less than about 20 percent by weight of the total of the Monomers and the polymerization pathogen, since larger amounts at polymerization pathogens affect the strength of the adhesive bonds. Preferably the Amount of the peroxy agent about 0.1 to 10 percent by weight of the total amount of monomers and polymerization agent.

To the mixture of the polymerizable monomeric acrylic acid ester and the peroxy pathogen, other substances such as quinones or polyhydric phenols as stabilizers, tertiary kmtrie or imides as accelerators, or other substances such as Yerdikker, coloring substances, etc., can be added. These additives are used in order to achieve technically valuable properties, ie a suitable viscosity and shelf life for longer periods of time (eg at least one month and preferably at least six months). These additives are particularly important when using peroxy pathogens other than organic hydroperoxides used. the anaerobic systems and anaerobically curing resins are described in detail in the US patents 2,895,950, .3 041,322, 3,043,820, 3,046,262, 3,203,941, 3,218,305 and

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3,300,547 ".

The polymerizable, liquid, anaerobic adhesives are preferred as monomers because the encapsulated products made from them are particularly suitable for bonding non-porous materials, especially metals, to one another. Due to their anaerobic properties, they are particularly valuable in the encapsulated state, because the capsules are previously can apply to the parts that are to be assembled ", then so much oxygen penetrates through the capsule walls that the hardening of the monomeric material is prevented." The parts covered with the capsules can be stored for a long time and shipped without loss of adhesive. At the time of joining, the pressure between the two surfaces to be joined is sufficient to break the capsules, releasing the anaerobic adhesive and overlooking the surfaces. Since there is no air between the surfaces, ■ the curing begins immediately, "So far, no one _else's" found only one component of existing adhesive that can be encapsulate this effect. Since the shell walls are made of the same homopolymer ana which forms in the polymerization of the monomeric core, no foreign substances are present which might affect the uninterruptedness of the bond between the two surfaces.

Cracked encapsulated monomers are also preferred because of their particular adaptability to process requirements (described in detail below), the speed with which the shell walls form, and the wide range of yiscosity with which they are made can so that αλ ?.! Slidung of .Einzelteilchen within a wide range Ym 7yrfahre3asbeä.ingungen is facilitated ,,

In a process according to the invention, the monomeric material is

ri £! -l introduced into a fluid in jsinselmengsn and then kept for e - .. '1-ΰ Mii2? for a long period of time with the polymerization catalyst ± L · Bä ^ ülmaiig to prevent the formation of the monomeric material

to enable encapsulating shells made of homopolymer. the Size of the finished, encapsulated product particles primarily according to the size of the individual amounts of the monomeric material which are introduced into the fluid, and therefore the method of introducing these individual amounts depends largely on the type of end product desired. .

In the inventive method the individual amounts of the monomeric material may be introduced into the fluid by passing it einsprüht eg _e from the outside into the fluid. However, the invention also includes the formation of the individual quantities in place, e.g., Be by the addition of the monomeric material to a _f g liquid in which this material is insoluble, and subsequent distribution of the monomeric material in the liquid in the form of small individual quantities by strong Stir.

The most advantageous methods of introducing the discrete quantities of monomeric material to produce small microcapsules make use of spraying the monomeric material into the Fluid or the other method described in the previous paragraph. Larger capsules can be produced by getting lets large drops fall from pipes or through a perforated plate. -

In many cases the fluid can be a gas, for example if the process is carried out in a conventional spray tower, but a liquid is preferably used, especially if the preferred anaerobic monomers described above are involved. With liquids you get a more reactive and varied system, and the control of the particle size and the shell wall thickness can be carried out more easily than in the gaseous state. Individual particles from the monomeric material can be produced in various ways. One can, for example, _o large drops of pipes, such as pipettes, drop into the liquid phase, and if the drops are large enough, they easily penetrate the liquid surface without losing its character as individual particles. This method

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however, it is generally not effective enough when it comes to small droplets because small droplets of the monomeric material gather at or near the surface of the liquid and therefore do not retain their individual character. "It has been found that small capsules insert themselves from tubes keeping the tubes slightly below the surface of the liquid and stirring the liquid during insertion. The size of the capsules depends on the size of the tube opening and the degree of stirring _o The smaller the opening and the stronger the stirring movement, the smaller the capsules are.

To produce large quantities of capsules, the monomeric material is preferably mixed in the liquid phase with vigorous stirring, the stirring movement taking on the task of bringing about the formation of the individual quantities of the monomeric material on the spot. So that these particles remain as individual particles until the encapsulating shell has formed, surface-active agents can also be added to the liquid. In general, the polymerization catalyst is preferably added after the individual particles have been produced; However, this is not absolutely necessary. “If the stirring movement is strong enough, you will also get satisfactory results if the monomeric material is suspended after the catalyst. If the capsules are produced in a liquid, the liquid must be of such a nature that the monomeric material is practically insoluble in it. ”If the monomeric material dissolves easily in the liquid, the individual particles are destroyed before the capsules dissolve can form. For the preferred anaerobic encapsulated monomers described above, water is preferred as the liquid.

Any polymerization catalyst can be used which catalyzed the homopolymerization of the monomeric material

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A number of such catalysts are available for various homopolymerizable monomers. The preferred catalysts for encapsulating anaerobic monomers within
of a liquid are sulfur dioxide and sodium bisulfite.
These two substances are soluble in water and lead to such a rapid homopolymerization on the surfaces of the individual quantities of the monomeric material that the capsules become
of the invention.

The amount of catalyst to be used in conjunction with the fluid
only needs to be enough to allow homopolymerization in that
to catalyze the extent described here. The amounts of catalyst vary from one system to another; However, it has "tended that 0.01 percent by weight of catalyst is generally sufficient in water to encapsulate the anaerobic monomers. The amount of catalyst is preferably between about 0.05 and 3.0 percent by weight, based on the water"
upper limit is not decisive; one achieves however
hardly any benefit if you have the catalyst in amounts of
more than about 5 percent by weight based on the water applies. However, if you use very soluble catalysts, such as sodium bisulfite, you can work with aqueous catalyst concentrations up to the saturation point without significantly changing the result, with the only exception that the capsule walls may be somewhat thicker.

The. Encapsulated particles described here can vary in size from microcapsules that are about 25 to 750 μ in size to macrocapsules that are about 1 to 3 mm in size or even larger. The maximum particle size of the encapsulated product according to the invention is only limited by the
Manufacturing method limited.

The microcapsules have a greater ability to vary and
more possible applications and therefore represent a preferred embodiment of the invention. The most preferred size is about 50 to 500 μ; it is particularly suitable

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for anaerobic adhesives and sealants. Capsules, the size = more than about 500 μ. ,, and especially those that are larger are than about 750 μ, are difficult to hold on to a surface and are too large for easy handling and Use. Particles in the range from 50 to 500 μ are small enough to fit between the threads of the mostly threaded provided objects, such as screws * mattem, bolts and Normal pipe thread on narrow threaded pipes and connections too fit. If the capsules are intended for this particular application, they must fit between the gripping entrances, so that they are not removed when the two mating surfaces are joined.

The capsules according to the invention have a wide range of applications. Sealants ™ and adhesives _B, especially the anaerobic adhesives and adhesives described above, consisting of only one component, can be applied to the parts intended to be joined after they have been produced »pische examples of products that combine with the encapsulated adhesive - and sealing means suitable before joining are nuts, bolts, screws, dowels, nails, rivets, pins, keyways, threaded or flat pipes, pipe connections intended for shrinking, such as metal pipes, and various hydraulic fittings, plastic caps, metal signs, etc. encapsulated products it -is possible, adhesives and sealants free iron Vera'ünnungs = transmit or foreign substances contained in such products _s previously the-apply · göiiden parts prior to assembly to the gusammeasufü "=.

furthermore, the adhesives and sealants according to Invention of other encapsulated, homopolymerizable product® sur available that have advantages, which read the above = - ■: -; iirielien similarly sincL 'independently of their intended purpose

are the © ingekapselten products free of n and Freud t off s _s erhaj the ¥ could "beeinträöhtigen t @ si d products. Yersaafi vxiü Hantio ^ img

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the facilitated since the encapsulated liquids may also be packaged as solids, Z ₀ as in bags, boxes or containers of plastics or other materials that would not come to the packaging of liquid monomers. At the point of use, the capsules are broken by the action of heat or mechanical pressure, thereby releasing the monomeric material.

The following examples illustrate the preparation of encapsulated Products according to the invention, ie of liquid monomers which are encapsulated in a shell, 'which from consists of a homopolymer formed from the monomeric material. The examples also explain the application the methods described above for making encapsulated monomers. Unless otherwise stated, The proportions and percentages relate to the Weight.

example 1

A homopolymerizable liquid monomeric material is made by mixing 90 g of polyethylene glycol dimethacrylate (medium Molecular weight 330), 6 g cumene hydroperoxide, 4 g tributylamine and less than 0.1 g minor components (dye, Ohinon).

5 ml of this monomeric material are added slowly (at a rate of about 3 ml per minute) through an injection needle with an outer diameter of 0.89 mm in 200 ml a 1 percent strength by weight aqueous sodium bisulfite solution injected. Here, the solution is with the help of a magnetic Stirrer at moderate speed (250 rev / min.) Stirred. The individuals forming at the tip of the needle Droplets of the monomeric material are removed from the needle tip by stirring the sodium bisulfite solution.

The task of the sodium bisulfite in the solution is the homopolymerization on the surface of the droplets in place and

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To catalyze site, so that around a core of liquid monomeric) material around a wrapper wall of homopolymer forms, laughing 2 minutes the EXj- ° · ^Ί "η sieved off from the solution, washed several times with water and then to dry on filter paper spread out ₀

The next day, the capsules are examined ι The mean particle diameter is 650 μ and the amount of core liquid (the unpolymerized monomeric material) $ 80> of the total weight of the capsules.

B is P, each _m 1 ^ 2

5 are injected at a rate of 5 ml / min in 200 ml _β Einei ⁰ 0.1 gewiclitsprozentigen aqueous solution of sulfur dioxide ml of liquid monomeric = Mate described in Example 1 rials. For this one uses a hypodermic needle with an external diameter of ₉ 0 4 mm, and the solution is stirred at a speed of 200 rev / min _o

As in example 1, a fluid core is formed from the monomeric material, which is in a shell made of homopolymer a = is encapsulated, which has formed from the monomeric material »The encapsulated product is soaked in Example 1 from the Jjösimg removed, washed and dried »

The closest are the capsules examined? The middle one The diameter of the capsules is 750 μ and the amount of core liquid is $ 85 of the total weight of the capsules »

Example 3

A 114 liter polyethylene container is charged with 30 liters of water containing 0.23 percent by weight of sodium polyacrylate, and the solution is drawn with the help of a stirrer blade equipped 0 "5 HP motor with a speed of 350 rpm, stirred.

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There will be 3 liters of liquid, homopolymerizable, monomeric material made by mixing the following ingredients:

Components & eWo- $

Polyethylene glycol dimethacrylate __ _

(average molecular weight 330) ^ * ^y

Acrylic acid 3 »O

Cumene hydroperoxide 3 »Ö

latent accelerator (benzoyl sulfimide and diethyl-p-toluidine in a weight ratio of 4: 3) '0.7

Minor components (dye, quinone) > 0.1

100.0

The 3 l monomeric material are slowly in the aqueous Pour solution while stirring and continue stirring for 15 minutes after addition. On it is located the monomeric material * in the form of separate quantities, which are suspended in the aqueous solution.

With continued stirring, a solution of 15 g of sodium bisulfite is obtained in 35 ml of water slowly added to the mixture of water and monomeric material. The mixture is then stirred for a further 1 minute and filter the mixture through a cheesecloth filter. The encapsulated product remains on the filter; one leaves it for several minutes Drain, wash it several times with water, and then leave it dry * ■

The encapsulated product is sieved off the next day. Above 90 percent by weight of the capsules have a diameter between 175 and 500 μ. The investigation shows that the amount of core fluid 75 # by the total weight of the capsules;

The encapsulated ones described in Examples 1-3 Products are durable. The anaerobic liquid core stays longer Time, e.g. 6 months or more, in the unpolymerized state. The capsule walls are so air-permeable that enough

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Oxygen can reach the liquid »in order to polymerize. tion to prevent »The encapsulated products can be applied to parts that are intended to be" assembled ", eg" B ₀ on nuts and bolts or on Hokr threads, and when the fitting parts are joined together, the capsules break and release aas liquid aionic material " . In view of the nature of the fitting parts, the access "where air smsoaen" is excluded, and the anaerobic product · hardens in the fair way ·

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Claims (10)

Claims 1. Encapsulated product, characterized by a core liquid monomeric material and one surrounding the core Shell made from the homopolymer of the monomeric material. 2. Encapsulated product according to claim 1, characterized in that that the homopolymer shell has been produced on the spot from the monomeric material. 3 · Product according to claim 1, characterized in that the liquid monomeric material a mixture of a polymerizable Acrylic acid ester and a peroxy polymerization agent is. 4. Product according to claim 3, characterized in that the liquid monomer is a polyacrylic acid ester of the general Porcnel It H ₂ O = COO '2 ir / \ E ¹ -ό-ο - (0H ₂ ) _m - ^6th V ³ y -C-O = GH, is, in which R is a hydrogen atom, an alkyl or hydroxyalkyl radical having 1 to 4 carbon atoms or one reading of the composition - 17 - 1522-f _ ' ß It 2
E a hydrogen or halogenated or an alkyl radical with 1 "to 4 carbon atoms * E a hydrogen atom ^ a hydroxyl group or a Sest of the composition O -0-GG = GH ₉ '2 IT ■ ' m is an integer of at least I ₃ ^ ₀ B ₀ from 1 to about or more, in particular from 1 "to about S ₉ η a whole number of at least I ₉ S ₀ B ₀ from 1" to about 20 or more; mean and ρ the value 0 or 1 hai *. " 5. Product after. Prmoh Ins-3 _»v daduroh in that the liquid monomers in PolyäthylesiglykoldimethacrFlat © ₀ 6 »Product according to claim S _9, characterized in that the Perozy polymerization pathogen is an organic hydroperoxide. 7s product according to claim I ₉ because it has a mean particle size of about 50 ms 750 μ « 8, A method for encapsulating Monoraerenj, characterized gekennseich = net that one Binzelmengen a houopolymerisierbaren monomeric material in a Pluid introduces _a the egg nzelmengen therein with a dis Homopoljmerisation the monomeric material catalyzing polymerization catalyst in Beruhrung holding "and the Einselsengen from düsm 5 ¹ IuId removed after an encapsulating shell made of homopolymer has formed » 9 »'/ learned in accordance with claim 6 _P dadureli _s that a polymerizable aorylic acid ester and a pero-polymerisation agent are used as the monoic material 18 - ORIGINAL INSPECTED 2023399 10. Verfaliren according to claim 9 »characterized in that one water is used as fluid and sulfur dioxide © sodium laisulphite is used as catalyst, 11 * The method according to claim 10, characterized in that the catalyst in amounts of about 0.05 "to 3.0 percent by weight, "based on the water. 12, Threaded item characterized by: that on the threaded part of the same the encapsulated product according to claim 7 adheres. - 19 109849/030