JP2006273880A - Emulsifying agent for emulsion polymerization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an emulsifying agent for an emulsion polymerization, excellent in polymerization stability and chemical stability, showing less foaming and capable of obtaining a polymer emulsion excellent in film gloss. <P>SOLUTION: This emulsifying agent for the emulsion polymerization is expressed by the following general formula (1), and contains a nonionic surfactant having 0.8-2.5 degree of branching and 1.10-1.20 Mw/Mn of the degree of multiple dispersion. Provided that, the above mentioned general formula (1) is: R-O-(AO)<SB>x</SB>-H [wherein, R is a 12-14C alkyl; AO is a 2-4C oxyalkylene; (x) is an integer of 1-100; and the addition form of the AO is a random addition, block addition or their mix-addition]. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an emulsifier for emulsion polymerization used in emulsion polymerization.

  Conventionally, as an emulsifier for emulsion polymerization, an alkylphenyl ether type nonionic surfactant obtained by adding an alkylene oxide such as ethylene oxide to an alkylphenol such as nonylphenol or octylphenol has been widely used. However, in recent years, since alkylphenol is hardly biodegradable, it has been pointed out that the burden on the environment is large. For this reason, as a hydrophobic group raw material for emulsifiers for emulsion polymerization, alkylphenols have been shifted to aliphatic alcohols.

On the other hand, in Patent Document 1 below, as an emulsifier for emulsion polymerization in which a hydrophobic group is an aliphatic alcohol residue, an ether-type compound obtained by adding an alkylene oxide to an alcohol having 13 carbon atoms synthesized by the oxo method. Nonionic or anionic surfactants are disclosed.
JP 2001-72702 A

  The performance required for the emulsifier for emulsion polymerization includes emulsion stability during polymerization, chemical stability of the resulting polymer emulsion, and the like. The emulsifier for emulsion polymerization disclosed in Patent Document 1 improves these improvements. Although the effect was recognized, it was still insufficient. In addition, when the obtained polymer emulsion is used for coating applications, it is required that the polymer emulsion has less foaming and that the film formed from the emulsion is excellent in glossiness. The polymer emulsion polymerized was insufficient in these respects.

  The present invention has been made in view of the above points, and it is possible to obtain a polymer emulsion that is excellent in emulsion stability during polymerization and chemical stability of the resulting polymer emulsion, has less foaming, and has excellent film gloss. An object of the present invention is to provide an emulsifier for emulsion polymerization.

  In the course of diligent investigations in view of the above points, the present inventors use a fatty alcohol having a specific range of branching degree as a hydrophobic group raw material, and set the polydispersity of the surfactant within a specific range. As a result, it was found that the above-mentioned problems were solved, and the present invention was completed.

That is, the emulsifier for emulsion polymerization according to the present invention is represented by the following general formula (1), the polydispersity Mw / Mn is 1.10 to 1.20, and the degree of branching is 0.8 to 2.5. It contains a nonionic surfactant.
R-O- (AO) x-H (1)
(In the formula, R represents an alkyl group having 12 to 14 carbon atoms, AO represents an oxyalkylene group having 2 to 4 carbon atoms, and x is an integer of 1 to 100. The addition form of AO is (Random addition, block addition, or mixed addition thereof.)

  The emulsifier for emulsion polymerization of the present invention is one in which R in the general formula (1) is derived from an alcohol obtained from an oxo reaction of a butene trimer.

  Moreover, the emulsifier for emulsion polymerization of the present invention may be one in which R is derived from an alcohol obtained from the Gerve reaction in the above general formula (1).

  The emulsifier for emulsion polymerization of the present invention can further contain polyethylene glycol.

  With the emulsifier for emulsion polymerization of the present invention, a polymer emulsion having good polymerization stability and chemical stability and less foaming can be obtained. Moreover, the particle diameter distribution of the obtained polymer emulsion is narrow, and a film having good gloss when used for coatings can be obtained.

  In the general formula (1), R represents an alkyl group having 12 to 14 carbon atoms. In the present invention, a branched aliphatic alcohol having 12 to 14 carbon atoms is used as a raw material alcohol for a hydrophobic group. Here, specific examples of R include isododecyl group, isotridecyl group, isotetradecyl group and the like. An isotridecyl group is preferable. Although not particularly limited, the hydrophobic group raw material may be a mixture of isotridecyl alcohol and another alcohol. As the other alcohol in this case, the above-mentioned branched aliphatic alcohol having 12 to 14 carbon atoms is preferably used. However, a branched aliphatic alcohol having 12 to 14 carbon atoms within the range not impairing the effects of the present invention. It can also be used. When the branched aliphatic alcohol having 12 to 14 carbon atoms is mixed, the ratio is preferably 10% by weight or less.

In the general formula (1), (AO) _X is a polyoxyalkylene moiety formed by addition polymerization of propylene oxide, ethylene oxide or the like to the raw material alcohol described above, PO is an oxypropylene group, EO is Each represents an oxyethylene group. The addition form of propylene oxide and ethylene oxide may be a random polymer chain, a block polymer chain, or a combination thereof. More preferably, propylene oxide is first added to the raw material alcohol, and then ethylene oxide is block-added so that the alcohol residue side becomes an oxypropylene group portion. In other words, the nonionic surfactant is more preferably represented by the following general formula (2). By adopting such a block addition form, the polymerization stability during emulsion polymerization is good, and the chemical stability of the resulting polymer emulsion and the gloss of the film are good.

R—O— (PO) _m (EO) _n —H (2)
Here, in the formula, R represents an alkyl group having 12 to 14 carbon atoms, EO represents an oxyethylene group, PO represents an oxypropylene group, m is an integer of 0 to 4, and n is an integer of 1 to 100. is there.

  In the alkyl moiety, the degree of branching is in the range of 0.8 to 2.5. When the degree of branching is less than 0.8, foaming of the resulting polymer emulsion increases. On the other hand, when the degree of branching is greater than 2.5, the particle size distribution of the resulting polymer emulsion becomes coarse, and a film having good gloss cannot be obtained when used for coating applications. On the other hand, the added mole number n of EO is 1 to 100, more preferably 5 to 80.

  The nonionic surfactant represented by the general formula (1) has a polydispersity (Mw / Mn) of 1.10 to 1 represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn). It must be within the range of .20. If the polydispersity Mw / Mn is greater than 1.20, the particle size distribution of the resulting polymer emulsion becomes coarse, and a film having good gloss cannot be obtained when used for coating applications. Conversely, when the polydispersity Mw / Mn is less than 1.10, not only the monomers that can be used for emulsion polymerization are limited, but also the polymerization stability becomes insufficient due to insufficient emulsification power. In order to set the polydispersity within the above range, the reaction conditions such as the kind and amount of the catalyst and the reaction temperature when the alkylene oxide is added to the raw material alcohol may be adjusted.

  The emulsifier for emulsion polymerization of the present invention may contain polyethylene glycol together with the nonionic surfactant represented by the above general formula (1), and further improve the polymerization stability by using polyethylene glycol together. Can do. As the polyethylene glycol, those having a number average molecular weight (Mn) of 20,000 or less are used, and more preferably those having a number average molecular weight of 500 to 10,000 are used. When polyethylene glycol is used in combination, it is preferably contained in an amount of 0.5 to 70 parts by weight, more preferably 1 to 30 parts by weight with respect to 100 parts by weight of the nonionic surfactant of the above formula (1).

  The emulsifier for emulsion polymerization of the present invention may further contain an anionic surfactant, thereby improving the polymerization stability during emulsion polymerization. Such an anionic surfactant is not particularly limited, and examples thereof include aliphatic soaps, rosin acid soaps, alkyl sulfonates, alkylaryl sulfonates, alkyl sulfosuccinates, polyoxyethylene alkyl sulfates, and polyoxyethylene alkyls. Examples thereof include aryl sulfates. When using an anionic surfactant together, it is preferable that 0.5-100 weight part is contained with respect to 100 weight part of nonionic surfactant of said Formula (1), More preferably, it is 5-60 weight part. . More preferably, it is 10-30 weight part.

  The emulsifier for emulsion polymerization of the present invention can be applied to emulsion polymerization of various monomers, and the type of the monomer is not particularly limited, but examples include methyl acrylate, ethyl acrylate, butyl acrylate, acrylic acid 2- Ethylhexyl, methyl methacrylate, butyl methacrylate, glycidyl methacrylate, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, acrylamide, methacrylamide, hydroxyethyl ester acrylate, hydroxyethyl ester methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, Acrylic monomers such as acrylic acid and methacrylic acid, aromatic monomers such as styrene, α-methylstyrene, vinyltoluene, p-methylstyrene and divinylbenzene, vinyl acetate Vinyl ester monomers such as vinyl, halogenated olefin monomers such as vinyl chloride and vinylidene chloride, conjugated diolefin monomers such as butadiene, isoprene and chloroprene, and others, ethylene, itaconic acid, fumaric acid, maleic acid, maleic acid And methyl. These monomers can be used alone or in combination of two or more.

  The emulsifier for emulsion polymerization of the present invention is usually used in an amount of 0.1 to 20% by weight, preferably 0.2 to 5% by weight, based on the total amount of monomers.

  For emulsion polymerization using the emulsifier for emulsion polymerization of the present invention, a conventionally known polymerization initiator can be used without particular limitation. Representative examples include hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane). And dihydrochloride.

  Further, redox polymerization can be performed using sodium bisulfite, ferrous ammonium sulfate, or the like as a polymerization accelerator.

  Further, as chain transfer agents, mercaptans such as α-methylstyrene dimer, n-butyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, carbon tetrachloride, carbon tetrabromide Halogenated hydrocarbons such as may be used.

  The polymer emulsion obtained using the emulsifier for emulsion polymerization of the present invention includes, for example, binders for printing inks, paints (for construction, household use, cans, electrodeposition coating, etc.), binders for inkjet media, and adhesives. It can be applied to wood, metal, paper, cloth, plastic, ceramic, other concrete, etc. as an adhesive, a coating agent, an impregnation reinforcing agent and the like.

  Hereinafter, the present invention will be specifically described by way of examples, but the scope of the present invention is not limited thereto. In the following examples, “part” is based on mass unless otherwise specified.

  Production examples of the emulsifier for emulsion polymerization used in the examples are as follows. In Table 1, (EO) is an abbreviation for ethylene oxide, and (PO) is an abbreviation for propylene oxide.

<Production Example 1>
An autoclave was charged with 200 parts (1 mole) of isotridecyl alcohol (branching degree 2.1) and 0.42 part of boron trifluoride (0.006 moles, 0.1% per crude product). Replaced with nitrogen. Next, after introducing 220 parts (5 mol) of ethylene oxide at a temperature of 70 ° C. and a reaction pressure of 0.25 MPa, the reaction solution was aged until the internal pressure decreased and became constant while maintaining the reaction temperature. Until cooled. Next, 1.02 part (0.018 mol) of potassium hydroxide was charged, and after introducing 220 parts (5 mol) of ethylene oxide at a temperature of 120 ° C. and a reaction pressure of 0.25 MPa, the internal pressure was maintained while maintaining the reaction temperature. Aged until the drop was constant. Then, after cooling a reaction liquid to 70 degreeC, it neutralized with 1.36 parts (0.013 mol) of 85 weight% lactic acid, and this invention product [1] was obtained.

<Production Example 2>
An autoclave was charged with 200 parts (1 mol) of isotridecyl alcohol (branch degree 2.1) and 2.02 parts (0.036 mol, 0.1% per crude product) of potassium hydroxide, and nitrogen was added to the autoclave. After the replacement, the pressure was reduced at 70 ° C. while stirring. After the internal pressure in the reactor reached 2.7 kPa, dehydration under reduced pressure was continued for 30 minutes. Subsequently, after raising the temperature to 110 ° C., 58 parts (1 mol) of propylene oxide was introduced at a reaction pressure of 0.20 MPa. After the introduction of propylene oxide, the reaction temperature was maintained, and aging was performed until the internal pressure decreased and became constant. Next, after introducing 1760 parts (40 moles) of ethylene oxide at a temperature of 120 ° C. and a reaction pressure of 0.25 MPa, the reaction temperature was maintained and aging was performed until the internal pressure decreased and became constant. Thereafter, the reaction solution was cooled to 70 ° C. and then neutralized with 4.19 parts of 85% by weight of lactic acid (0.040 mol, 1.1 mol equivalent to potassium hydroxide), and the product of the present invention [2] Got.

<Production Example 3>
An autoclave was charged with 200 parts (1 mole) of isotridecyl alcohol (branch degree 2.1) and 3.72 parts (0.067 moles, 0.1% per crude product) of potassium hydroxide, and nitrogen was added to the autoclave. After the replacement, the pressure was reduced at 70 ° C. while stirring. After the internal pressure in the reactor reached 2.7 kPa, dehydration under reduced pressure was continued for 30 minutes. Next, 3520 parts (80 moles) of ethylene oxide were introduced at a temperature of 120 ° C. and a reaction pressure of 0.25 MPa, and then aging was performed until the internal pressure decreased and became constant while maintaining the reaction temperature. Thereafter, the reaction solution was cooled to 70 ° C. and then neutralized with 4.38 parts of glacial acetic acid (0.073 mol, 1.1 mol equivalent per potassium hydroxide) to obtain the product [3] of the present invention. It was.

<Production Example 4>
Isotridecyl alcohol (branch degree 2.1) was changed to the alcohol shown in Table 1 below, the amount of ethylene oxide introduced was changed to the ratio shown in Table 1 below, and the catalyst amount was changed accordingly (as opposed to Except for 0.1% per crude product), the product [4] of the present invention and the comparative products [3] [6] [7] were obtained in the same manner as in Production Example 3.

<Production Example 5>
An autoclave was charged with 200 parts (1 mol) of isotridecyl alcohol (branch degree 2.1) and 0.64 part of boron trifluoride (0.010 mol, 0.1% per crude product). Replaced with nitrogen. Next, after introducing 440 parts (10 moles) of ethylene oxide at a temperature of 70 ° C. and a reaction pressure of 0.25 MPa, the mixture was aged until the internal pressure decreased and became constant while maintaining the reaction temperature. Thereafter, the reaction solution was cooled to 60 ° C. to obtain a comparative product [1].

<Production Example 6>
An autoclave is charged with 200 parts (1 mol) of isotridecyl alcohol (branch degree 2.1) and 1.96 parts of potassium hydroxide (0.035 mol, 0.1% per crude product), and the autoclave is filled with nitrogen. After the replacement, the pressure was reduced at 70 ° C. while stirring. After the internal pressure in the reactor reached 2.7 kPa, dehydration under reduced pressure was continued for 30 minutes. Next, after introducing 1760 parts (40 moles) of ethylene oxide at a temperature of 170 ° C. and a reaction pressure of 0.25 MPa, the reaction temperature was maintained and aging was performed until the internal pressure decreased and became constant. Thereafter, the reaction solution was cooled to 70 ° C. and then neutralized with 2.31 parts of glacial acetic acid (0.038 mol, 1.1 mol equivalent to potassium hydroxide) to obtain a comparative product [2]. .

<Production Example 7>
Comparative product [4] was obtained in the same manner as in Production Example 2, except that isotridecyl alcohol (branch degree 2.1) was changed to isotridecyl alcohol (branch degree 2.9).

<Production Example 8>
Comparative product [5] was prepared in the same manner as in Production Example 6 except that the amount of ethylene oxide introduced was changed to 3520 parts (80 mol) and the amount of catalyst was changed accordingly (0.1% per crude product). Obtained.

<Production Example 9>
80 parts of the present invention product [1] obtained in Production Example 1 and 20 parts of polyethylene glycol having an average molecular weight of 660 were mixed to obtain the present product [5].

<Production Example 10>
90 parts of the product [2] obtained in Production Example 3 and 10 parts of polyethylene glycol having an average molecular weight of 2200 were mixed to obtain a product [6] of the present invention.

  The polydispersities were measured for the products [1] to [4] of the present invention and the comparative products [1] to [7]. The measurement method is as follows, and the results are shown in Table 1.

[Polydispersity measurement]
By performing GPC measurement under the following conditions, the polydispersity Mw / Mn, which is the extent of the molecular weight distribution of the surfactant, was determined.
Column: Shodex GPC KF-G + Shodex GPC KF-803 + Shodex GPC KF-802.5 + Shodex GPC KF-802 + Shodex GPC KF-801 (all manufactured by Showa Denko KK)
Mobile phase: THF (0.8 mL / min)
Column temperature: 40 ° C
Detector: RI
Sample injection: 100 μL of 1 wt% solution

[Degree of branching]
The degree of branching is a numerical value obtained by obtaining the number of methyl groups by H ¹ -NMR measurement and subtracting 1 corresponding to the terminal methyl group site.

<Examples 1-4 and Comparative Examples 1-5>
A reaction vessel equipped with a stirrer, reflux condenser, thermometer and dropping funnel was charged with 131 parts of distilled water and 0.5 part of sodium bicarbonate as a buffering agent, heated to 80 ° C., and dissolved oxygen was added with nitrogen gas. Removed. Separately, 75 parts of methyl methacrylate, 171 parts of ethyl acrylate, 4 parts of acrylic acid, 8 parts of an emulsifier for emulsion polymerization, and 110 parts of distilled water were mixed to prepare a monomer emulsion. Next, 40 parts of the monomer emulsion prepared above were added all at once to the reaction vessel. After stirring for 10 minutes, 0.5 part of ammonium persulfate as a polymerization initiator was added and stirred for 10 minutes. Next, the remaining monomer emulsion was added dropwise over 3 hours to conduct a polymerization reaction, cooled to 40 ° C., and adjusted to pH 8-9 with aqueous ammonia to obtain a polymer emulsion.

The emulsifier for emulsion polymerization used is as shown in Table 2 below, and the following anionic surfactant was used in combination with 10% by weight based on the nonionic surfactant.
a. Lauryl sulfate sodium salt b. Linear alkylbenzene sulfonic acid sodium salt c. Polyoxyethylene styrenated phenyl ether phosphate (5EO)

  The resulting polymer emulsion was evaluated for polymerization stability, chemical stability, particle size, particle size distribution, and film glossiness. The evaluation method is as follows, and the results are shown in Table 2.

[Polymerization stability]
The polymer emulsion after polymerization was filtered using an 80 mesh filter cloth, and the residue on the filter cloth was washed with water and dried at 105 ° C. for 3 hours. The weight of the residue after drying was measured and expressed as a weight ratio (%) to the total solid content.

[Chemical stability]
Add 10 mL of a 6 mol / L calcium hydroxide aqueous solution to 10 g of the polymer emulsion while stirring, filter using an 80 mesh filter cloth after stirring for 5 minutes, and measure the dry weight of the aggregated polymer that does not pass through the filter cloth. It was expressed as a weight ratio (%) to the solid content.

[Particle size]
The particle size distribution was measured with a dynamic light scattering particle size distribution analyzer (MICROTRAC UPA 9340 manufactured by Nikkiso) and displayed in μm.

[Particle size distribution]
The standard deviation was obtained from the particle size distribution obtained by the dynamic light scattering particle size distribution measurement, and was expressed as a value obtained by dividing the standard deviation by the median diameter, that is, relative standard deviation (%).

[Glossiness of film]
A 0.5 mm (wet) emulsion film was formed on a glass plate and allowed to stand at room temperature for 18 to 20 hours to prepare a film. The glossiness of this film was visually evaluated in three stages: ○ (excellent), Δ (possible), and × (impossible).

<Examples 5-7 and Comparative Examples 6-8>
A reaction vessel equipped with a stirrer, reflux condenser, thermometer and dropping funnel was charged with 131 parts of distilled water and 0.5 part of sodium bicarbonate as a buffering agent, heated to 80 ° C., and dissolved oxygen was added with nitrogen gas. Removed. Separately from this, 100 parts of styrene, 146 parts of butyl acrylate, 4 parts of acrylic acid, 8 parts of an emulsifier for emulsion polymerization, and 110 parts of distilled water were mixed to prepare a monomer emulsion containing an emulsifier for emulsion polymerization. Next, 40 parts of the monomer emulsion prepared above were added all at once to the reaction vessel, and after stirring for 10 minutes, 0.5 part of potassium persulfate as a polymerization initiator was added and stirred for 10 minutes. Next, the remaining monomer emulsion was added dropwise over 3 hours to conduct a polymerization reaction, cooled to 40 ° C., adjusted to pH 8-9 with an aqueous sodium hydroxide solution to obtain a polymer emulsion.

  The emulsifiers for emulsion polymerization used are as shown in Table 3 below, and 10% by weight of polyoxyethylene lauryl sulfate sodium salt (5EO) was used as the combined anionic surfactant.

  The resulting polymer emulsion was evaluated for polymerization stability, particle size, and foamability. The evaluation method of foamability is as follows, and the other evaluation methods are the same as those in the above examples. The results are shown in Table 3.

[Bubbling]
20 mL of the polymer emulsion and 10 mL of water were placed in a 100 mL Nessler tube at room temperature, foamed by shaking (15 times; once / 2 seconds), and displayed as the amount of foam (mL) after standing for 5 minutes.

<Examples 8 to 9 and Comparative Examples 9 to 10>
A reaction vessel equipped with a stirrer, reflux condenser, thermometer and dropping funnel is charged with 131 parts of distilled water and 0.5 part of sodium hydrogen carbonate as a buffer, heated to 70 ° C., and dissolved oxygen is added with nitrogen gas. Removed. Separately, 250 parts of vinyl acetate, 8 parts of an emulsifier for emulsion polymerization, and 110 parts of distilled water were mixed to prepare a monomer emulsion containing an emulsifier for emulsion polymerization. Next, 40 parts of the monomer emulsion prepared above were added all at once to the reaction vessel. After stirring for 10 minutes, 0.5 part of ammonium persulfate as a polymerization initiator was added and stirred for 10 minutes. Next, the remaining monomer emulsion was added dropwise over 3 hours to conduct a polymerization reaction, cooled to 40 ° C., adjusted to pH 6 to 7 with aqueous ammonia to obtain a polymer emulsion. The emulsifier for emulsion polymerization used is as shown in Table 4 below.

  The resulting polymer emulsion was evaluated for polymerization stability and particle size. The evaluation method is the same as in the above example. The results are shown in Table 4.

As shown by the above examples and comparative examples, the emulsion polymerization emulsifier of the present invention has a particularly limited range of branching and a particularly limited alkylene oxide addition form, so that the polymerization stability and chemical stability are good. A polymer emulsion with less foaming was obtained. Moreover, the glossiness of the film was also excellent.

  In contrast, in the comparative product [3] having a branching degree of less than 0.8, as shown in Comparative Example 6, the foaming of the polymer emulsion was large. Further, in the comparative product [4] having a degree of branching exceeding 2.5, as shown in Comparative Example 3, the glossiness of the film was inferior. In comparative products [2] and [5] having a polydispersity exceeding 1.20, as shown in Comparative Examples 2 and 4, the glossiness of the film was inferior. In addition, in the comparative product [1] having a polydispersity of less than 1.10, as shown in Comparative Examples 1 and 9, the polymerization stability was insufficient.

  Since the emulsifier for emulsion polymerization according to the present invention has the above-described excellent effects, it can be preferably used as an emulsifier for emulsion polymerization of various monomers, particularly with less foaming, and the gloss of the film. Since an excellent polymer emulsion can be obtained, it can be particularly preferably used as an emulsifier for emulsion polymerization of a polymer emulsion used for coating.

Claims (4)

It is represented by the following general formula (1), characterized by containing a nonionic surfactant having a polydispersity Mw / Mn of 1.10 to 1.20 and a branching degree of 0.8 to 2.5. Emulsifier for emulsion polymerization.
R-O- (AO) x-H (1)
(In the formula, R represents an alkyl group having 12 to 14 carbon atoms, AO represents an oxyalkylene group having 2 to 4 carbon atoms, and x is an integer of 1 to 100. The addition form of AO is (Random addition, block addition, or mixed addition thereof.)   The emulsifier for emulsion polymerization according to claim 1, wherein in the general formula (1), R is derived from an alcohol obtained from an oxo reaction of a butene trimer.   The emulsifier for emulsion polymerization according to claim 1, wherein, in the general formula (1), R is derived from an alcohol obtained from the Gerbe reaction. The emulsifier for emulsion polymerization according to claims 1 to 3, further comprising polyethylene glycol.