Copolymers of cyclic ketene acetal monomers

Abstract

The invention relates to a multi-stage copolymer, preferably in the form of a solid resin, obtainable by multi-stage, radically initiated bulk or solution polymerization. A) in a first stage, copolymerizing one or more cyclic ketene acetal monomers a1) and one or more monomers a2) selected from the group consisting of vinyl esters comprising carboxylic acids having 1 to 15 C atoms, the invention relates to a method for producing a copolymer comprising the steps of a) polymerizing one or more ethylenically unsaturated monomers b1) containing acid groups in a first stage, b) polymerizing one or more ethylenically unsaturated monomers b1) containing acid groups in the presence of the copolymer from the first stage a), in a second stage, b) polymerizing one or more ethylenically unsaturated monomers b1) containing acid groups in the presence of the copolymer from the first stage a), and b) polymerizing one or more ethylenically unsaturated monomers b2) containing acid groups in the presence of the copolymer from the first stage a).

Description

Technical Field

[0001] The present invention relates to copolymers of cyclic ketene acetal monomers, in particular in the form of solid resins or aqueous dispersions or water-redispersible powders, to a process for preparing them by free-radically initiated polymerization, and to their use, for example in adhesives or coating compositions, in particular for the production of textiles. Background Art

[0002] For environmental reasons, there is an increasing demand for improving the biodegradability of polymers based on ethylenically unsaturated monomers, such as acrylates, vinyl esters, halogenated olefins or vinyl aromatic compounds. One method for this is the incorporation of comonomers that are unstable under natural conditions by polymerization. For example, US5541275 describes the copolymerization of vinyl esters and cyclic ketene acetals, in particular 2-methylene-1,3-dioxy-hydrocarbon ring systems, such as 2-methylene-1,3-dioxepane (MDO). Such cyclic ketene acetal monomers can be incorporated into the polymer chain by ring-opening polymerization, as a result of which ester bonds are introduced into the main chain of the polymer as predetermined breaking points and the biodegradability of the polymer is improved, as described, for example, in US11111328.

[0003] However, such unstable monomers may be unstable even under polymerization conditions and have a tendency towards side reactions or decomposition reactions, and it is therefore challenging for these unstable monomers to be incorporated into these polymers by polymerization in a controlled and as complete a manner as possible. For example, cyclic ketene acetals have a tendency to hydrolyze even under aqueous emulsion polymerization conditions and are then no longer polymerizable, as emphasized in US5541275 and US11111329. For example, MDO immediately hydrolyzes in water to form the corresponding 4-hydroxybutyl acetate of the following formula:

[0004] CUPittman, Journal of Organic Chemistry, 1995, 60, pp. 5729-5731 and B. Capon, Journal of American Chemical Society, Vol. 103, No. 7, 1981, pp. 1765-1768 also reported the rapid hydrolysis of 2-methylene-1,3-dioxolane or 2-methylene-1,3-dioxepane. Although the literature does discuss the emulsion polymerization of MDO or other cyclic ketene acetal monomers, the applicant's own reproduction of such a process shows that the hydrolytically unstable monomers are not significantly incorporated into the polymer, but mainly form the corresponding hydrolysis products, as shown by the comparative example 9 of the present application. The applicant's own experiments on the hydrolysis kinetics of cyclic ketene acetals also illustrate these problems in emulsion polymerization.

[0005] Even acid-containing vinyl comonomers such as acrylic acid can lead to hydrolysis of cyclic ketene acetals, so the preparation of copolymers of acid-containing vinyl monomers and cyclic ketene acetal monomers is particularly challenging. In addition, cyclic ketene acetals can exhibit unfavorable co-polymerization properties, which can also prevent the formation of copolymers. In summary, therefore, providing copolymers of cyclic ketene acetals and acid-containing vinyl monomers, especially in the form of aqueous dispersions, is particularly problematic.

[0006] US 10287380B describes the preparation of copolymers of 80 to 98% by weight of methacrylate and 2 to 10% by weight of cyclic ketene acetal by bulk or solution polymerization. JP 2017210503 relates to bulk or solution polymers of methacrylate a1) and cyclic ketene acetal a2) with a weight ratio of a2) / a1) of 1 / 99 to 20 / 80. US 11111328 and US 11111329 describe emulsion polymerization using vinyl esters, cyclic ketene acetals and ethylenically unsaturated acid monomers. Summary of the invention

[0007] Against this background, it was an object to provide copolymers of cyclic ketene acetal monomers and ethylenically unsaturated monomers carrying acid groups, in particular in the form of aqueous dispersions.

[0008] This object was surprisingly achieved by first preparing the copolymer by means of a) a cyclic ketene acetal monomer and a further ethylenically unsaturated monomer and b) a ethylenically unsaturated monomer carrying acid groups in a multistage, free-radically initiated bulk or solution polymerization and subsequently converting the copolymer obtained in this way into an aqueous dispersion. To this end, it has proven necessary to polymerize the cyclic ketene acetal monomer and the further ethylenically unsaturated monomer in a first stage a) of the multistage polymerization and subsequently polymerize the ethylenically unsaturated monomer carrying acid groups in a further stage b).

[0009] The present invention provides multistage copolymers obtainable by multistage, free-radically initiated bulk or solution polymerization, in particular in the form of solid resins, characterized in that

[0010] a) in a first stage, copolymerizing one or more cyclic ketene acetal monomers a1) and one or more monomers a2) selected from the group consisting of vinyl esters of carboxylic acids having 1 to 15 carbon atoms, methacrylates or acrylates of carboxylic acids with unbranched or branched alcohols having 1 to 15 carbon atoms, olefins, dienes, vinylaromatics and vinylhalides, and,

[0011] b) In a further stage, one or more ethylenically unsaturated monomers b1) carrying acid groups are polymerized in the presence of the copolymer from the first stage a).

[0012] The multistage copolymer is preferably in the form of a solid resin, an aqueous dispersion or a water-redispersible powder.

[0013] The present invention further provides a multistage copolymer in the form of an aqueous dispersion obtainable by dispersing one or more multistage copolymers of the present invention (eg in the form of a solid resin) in water.

[0014] The present invention further provides a multistage copolymer in the form of a water-redispersible powder obtainable by drying an aqueous dispersion of the multistage copolymer according to the invention.

[0015] Since they are prepared by multistage polymerization, the multistage copolymers according to the invention inevitably differ in structure from the polymer products from the single-stage polymerization process. This can be manifested, for example, in different water dispersibility or different glass transition temperatures Tg of the multistage copolymers according to the invention and conventional single-stage polymers, despite the identical monomer composition. Therefore, the process characteristics of the multistage polymerization are reflected in the structural characteristics of the multistage copolymers.

[0016] Preferred is the cyclic ketene acetal monomer a1 of the general formula 1)

[0017] (1)

[0018] Where n = 0, 1, 2 or 3;

[0019] R is a hydrogen atom or a C1-C6 alkyl group;

[0020] R 1 and R 2 are independently a hydrogen atom or a C1-C 12 an alkyl, phenyl, vinyl or halogen group; or R 1 and R 2 Together with the carbon atoms to which they are bonded, they form a fused benzene ring or a fused C3-C7 alicyclic ring; and

[0021] R 1’ and R 2’ are independently a hydrogen atom or a C1-C 12 an alkyl, phenyl, vinyl or halogen group; or R 1 and R 1’ and / or R 2 and R 2’ forming an exocyclic double bond; and

[0022] R 3 and R 3’ are independently a hydrogen atom or a C1-C 12 an alkyl, phenyl, vinyl or halogen group; or R 3 and R 3’ forming an exocyclic double bond or a spirocycloaliphatic group or a spiro-2-methylene-1,3-dioxepanyl group; or R 3 and R 3’ Forming an internal double bond, a fused benzene ring, or a fused C3-C7 alicyclic ring with the carbon atom to which they are bonded;

[0023] wherein optionally one or more, preferably non-adjacent -(CR 3 R 3’ ) group, particularly preferably a -(CR 3 R 3’ ) groups are each replaced by an oxygen atom.

[0024] Preferably, if n=1, then R 3 and R 3’ are independently a hydrogen atom or a C1-C 12 an alkyl, phenyl, vinyl or halogen group; or R 3’ and R 3’ An exocyclic double bond or a spirocycloaliphatic group or a spiro-2-methylene-1,3-dioxepanyl group is formed.

[0025] Preferably, if n=2, then R 3 and R 3’are independently a hydrogen atom or a C1-C 12 an alkyl, phenyl, vinyl or halogen group; or R 3 and R 3’ With the carbon atom to which they are bonded they form an internal double bond, a fused benzene ring or a fused C3-C7 alicyclic ring.

[0026] In the general formula (1) for the cyclic ketene acetal monomer a1), n ​​preferably has a value of 2.

[0027] Group R, R 1 , R 1’ , R 2 , R 2’ , R 3 and R 3’ Each independently preferably is a hydrogen atom or a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group, a benzyl group or a chloro group; particularly preferably is a hydrogen atom or a methyl group, a phenyl group or a benzyl group; most preferably is a hydrogen atom or a methyl group.

[0028] In a preferred embodiment of formula (1), n=2 and R, R 1 , R 1’ , R 2 , R 2’ , R 3 and R 3’ Each is a hydrogen atom.

[0029] Examples of the cyclic ketene acetal monomers include 2-methylene-1,3-dioxolane, 2-methylene-4-methyl-1,3-dioxolane, 2-methylene-4,5-dimethyl-1,3-dioxolane, 8-methylene-7,9-dioxabicyclo[4.3.0]nonane, 2-methylene-1,3-dioxane, 2-methylene-5-methyl-1,3-dioxane, 2-methylene-5,5-dimethyl-1,3-dioxane, 2-methylene-1,3-dioxolane-5-methyl-1,3-dioxane. Spirocyclopentane, 2-methylene-1,3-dioxolane-5-spirocyclopentane, 2-methylene-1,3-dioxepane, 2-methylene-1,3-dioxocane, 2-methylene-4-phenyl-1,3-dioxolane, 4,7-dimethyl-2-methylene-1,3-dioxepane, 5,6-benzo-2-methylene-1,3-dioxepane, 2-methylene-1,3,6-trioxocane and 2-methylene-1,3,5-trioxane.

[0030] 2-Methylene-1,3-dioxepane (MDO) is most preferred.

[0031] The preparation of cyclic ketene acetal monomers a1) is known from the literature and is described by way of example in JP 2017210503. Cyclic ketene acetal monomers are also commercially available.

[0032] The multistage copolymer is based on cyclic ketene acetal monomers a1) to an extent of preferably 5 to 99% by weight, more preferably 15 to 95% by weight, even more preferably 20 to 70% by weight, particularly preferably 22 to 50% by weight and most preferably 25 to 40% by weight, based on the total weight of the monomers of stage a), or monomers a1), a2) and optionally a3.

[0033] The multistage polymer is based on cyclic ketene acetal monomers a1) to an extent of preferably 5 to 99% by weight, more preferably 15 to 95% by weight, even more preferably 20 to 70% by weight, particularly preferably 22 to 50% by weight and most preferably 25 to 40% by weight, based on the total weight of the multistage copolymer.

[0034] The ring-opening polymerization of the cyclic ketene acetal monomer a1) generally produces a monomer unit a1 of the following formula (2):

[0035] (2).

[0036] The monomer units a1) preferably comprise ester groups and particularly preferably aliphatic groups having ester groups, which most preferably do not carry any further functional groups.

[0037] The monomers a2) of the first stage a) are selected from the group comprising vinyl esters of carboxylic acids having 1 to 15 carbon atoms, methacrylates or acrylates of carboxylic acids with unbranched or branched alcohols having 1 to 15 carbon atoms, olefins, dienes, vinyl aromatic compounds and vinyl halides.

[0038] Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, vinyl stearate, 1-methylvinyl acetate, vinyl pivalate and vinyl esters of branched or unbranched monocarboxylic acids having 5 to 20 carbon atoms, for example vinyl esters of α-branched monocarboxylic acids having 5 to 13 carbon atoms, for example VeoVa 9R or VeoVa 10R (trade name Hexion). Particularly preferred is vinyl acetate.

[0039] Preferred methacrylates or acrylates are esters of unbranched or branched alcohols having 1 to 15 carbon atoms, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, norbornyl acrylate. Particularly preferred are methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate and 2-ethylhexyl acrylate.

[0040] Preferred olefins or dienes are ethylene, propylene and 1,3-butadiene. Preferred vinyl aromatic compounds are styrene and vinyl toluene. Preferred halogenated olefins are vinyl chloride.

[0041] Preferred monomers a2) are methacrylates or acrylates and in particular vinyl esters, such as vinyl acetate.

[0042] Particular preference is also given to using a plurality of monomers a2) (monomer mixture a2)).

[0043] Examples of monomer mixtures a2) are monomer mixtures a2) of vinyl acetate with ethylene, monomer mixtures a2) of vinyl acetate with ethylene and one or more further vinyl esters), monomer mixtures a2) of vinyl acetate with ethylene and acrylic esters), monomer mixtures a2) of vinyl acetate with ethylene and vinyl chloride), monomer mixtures a2) of styrene and (meth)acrylic esters and monomer mixtures a2) of styrene with 1,3-butadiene.

[0044] Preference is given to monomer mixtures a2 of vinyl acetate and 1 to 40% by weight of ethylene); monomer mixtures a2 of vinyl acetate with 1 to 40% by weight of ethylene and 1 to 50% by weight of one or more further comonomers from the group of vinyl esters having 1 to 12 carbon atoms in the carboxyl group, such as vinyl propionate, vinyl laurate, vinyl esters of α-branched carboxylic acids having 5 to 13 carbon atoms, such as VeoVa9R, VeoVa10R, VeoVa11R; vinyl acetate, 1 to 40% by weight of ethylene and preferably 1 to 60% by weight of (meth)acrylic esters of unbranched or branched alcohols having 1 to 15 carbon atoms, in particular n-butyl acrylate or 2-butyl acrylate. ethylhexyl acrylate); and monomer mixtures a2) with 30 to 75% by weight of vinyl acetate, 1 to 30% by weight of vinyl laurate or of vinyl esters of α-branched carboxylic acids having 5 to 13 carbon atoms, and 1 to 30% by weight of (meth)acrylic esters of unbranched or branched alcohols having 1 to 15 carbon atoms, in particular n-butyl acrylate or 2-ethylhexyl acrylate), which may also contain 1 to 40% by weight of ethylene; monomer mixtures a2 with vinyl acetate, 1 to 40% by weight of ethylene and 1 to 60% by weight of vinyl chloride); where the figures for % by weight, based in each case on the total weight of the monomer mixture a2), add up to 100% by weight.

[0045] Preference is also given to monomer mixtures a2 of methyl methacrylate with n-butyl acrylate and / or 2-ethylhexyl acrylate and optionally ethylene); monomer mixtures a2 of styrene and one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate; monomer mixtures a2 of vinyl acetate with one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and optionally ethylene); monomer mixtures a2 of styrene with 1,3-butadiene); wherein the figures in % by weight, based in each case on the total weight of the monomer mixture a2), add up to 100% by weight.

[0046] The multistage copolymer is based on monomers a2) to an extent of preferably 1 to 95% by weight, more preferably 5 to 85% by weight, particularly preferably 30 to 80% by weight and most preferably 60 to 75% by weight, based on the total weight of the monomers of stage a), or monomers a1), a2) and optionally a3).

[0047] The multistage copolymer is based on monomers a2) to an extent of preferably 1 to 95 wt %, more preferably 5 to 85 wt %, particularly preferably 30 to 80 wt % and most preferably 60 to 75 wt %, based on the total weight of the multistage copolymer.

[0048] The copolymers from the first stage a) may optionally additionally be based on one or more auxiliary monomers a3). Examples of auxiliary monomers a3) are ethylenically unsaturated carboxamides, preferably acrylamide; diesters of fumaric acid, such as diethyl and diisopropyl. Further examples are pre-crosslinking comonomers, such as polyethylenically unsaturated comonomers, for example divinyl adipate, diallyl maleate, allyl methacrylate or triallyl cyanurate, or post-crosslinking comonomers, such as methyl methacrylamidoglycolate (MAGME), N-methylolacrylamide (NMA), N-methylolmethacrylamide (NMMA), N-methylolallylcarbamate, alkyl ethers, such as isobutoxy ethers or esters of N-methylolacrylamide, N-methylolacrylamide and N-methylolallylcarbamate. Also suitable are epoxy-functional comonomers, such as glycidyl methacrylate and glycidyl acrylate. Further examples are silicon-functionalized comonomers such as acryloxypropyltri(alkoxy)silanes and methacryloxypropyltri(alkoxy)silanes, vinyltrialkoxysilanes and vinylmethyldialkoxysilanes, in which the alkoxy groups present may be, for example, methoxy, ethoxy and ethoxypropylene glycol ether groups. Mention should also be made of monomers having hydroxyl or CO groups, such as hydroxyalkyl methacrylates and acrylates such as hydroxyethyl, hydroxypropyl or hydroxybutyl of acrylic acid or methacrylic acid, and compounds such as diacetone acrylamide and acetoacetoxyethyl of acrylic acid or methacrylic acid. Further examples also include vinyl ethers such as methyl vinyl ether, ethyl vinyl ether or isobutyl vinyl ether.

[0049] The multistage copolymer is based on auxiliary monomers a3) to an extent of preferably 0 to 20 wt %, particularly preferably 0.5 to 10 wt %, based on the total weight of the monomers of stage a) or of the monomers a1), a2) and optionally a3).

[0050] The multistage copolymer is based on auxiliary monomers a3) to an extent of preferably 0 to 20% by weight, particularly preferably 0.5 to 10% by weight, based on the total weight of the multistage copolymer.

[0051] The multistage copolymer is based on monomers a1), a2) and optionally a3) to an extent of preferably 85 to 99.5% by weight, particularly preferably 90 to 99% by weight and most preferably 92 to 97% by weight, based on the total weight of the multistage copolymer.

[0052] In step a), preferably no ethylenically unsaturated acid monomers and / or preferably no ethylenically unsaturated acid anhydrides are copolymerized, particularly preferably no monomers b1).

[0053] Ethylenically unsaturated monomers b1) carrying acid groups may be, for example, ethylenically unsaturated carboxylic acids, ethylenically unsaturated acid anhydrides, ethylenically unsaturated phosphoric acids, ethylenically unsaturated sulfonic acids or ethylenically unsaturated sulfuric acids, or salts thereof.

[0054] Examples of ethylenically unsaturated carboxylic acids are acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, crotonic acid, maleic acid and fumaric acid, vinylacetic acid; or monoesters of maleic acid or fumaric acid, such as monoethyl and monoisopropyl. Examples of ethylenically unsaturated anhydrides are maleic anhydride, methacrylic anhydride and acrylic anhydride. Examples of ethylenically unsaturated phosphoric acids are vinylphosphonic acid, 2-hydroxyethyl methacrylate phosphate, ethyl methacrylate phosphate and 2-(methacryloyloxy)ethylphosphonic acid. Examples of ethylenically unsaturated sulfonic acids are 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), vinylsulfonic acid, allylsulfonic acid, methylallylsulfonic acid, styrenesulfonic acid, vinylbenzenesulfonate, 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate, 2-propylene-1-sulfonic acid and acrylamidoglycolic acid.

[0055] Ethylenically unsaturated sulfonic acids and in particular ethylenically unsaturated carboxylic acids are preferred as monomers b1).

[0056] Preferred ethylenically unsaturated carboxylic acids are acrylic acid, methacrylic acid and fumaric acid. Preferred ethylenically unsaturated sulfonic acids are vinylsulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid.

[0057] The multistage copolymer is based on monomers b1) to an extent of preferably 0.5 to 15 wt %, particularly preferably 1 to 10 wt % and most preferably 3 to 8 wt %, based on the total weight of the monomers of stage a) or monomers a1), a2) and optionally a3).

[0058] The multistage copolymer is based on monomers b1) to an extent of preferably 25 to 100% by weight, particularly preferably 50 to 100% by weight and most preferably 90 to 100% by weight, based on the total weight of the monomers of stage b) or of monomers b1) and b2).

[0059] The multistage copolymer is based on monomer b1) to an extent of preferably 0.5 to 15 wt %, particularly preferably 1 to 10 wt % and most preferably 3 to 8 wt %, based on the total weight of the multistage copolymer.

[0060] Furthermore, one or more further ethylenically unsaturated monomers b2) which are different from the monomers b1) can be copolymerized in step b).

[0061] The monomers b2) can be, for example, the above-mentioned monomers a2) and / or auxiliary monomers a3) with the above-mentioned preferences.

[0062] The multistage copolymer is based on monomers b2) to an extent of preferably 0 to 75 wt %, more preferably 0 to 50 wt %, even more preferably 0 to 10 wt %, based on the total weight of the monomers of stage b) or of monomers b1) and b2).

[0063] Particularly preferably, no monomers b2) are used in stage b).

[0064] In stage b), it is also particularly preferred not to use cyclic ketene acetal monomers a1).

[0065] Most preferably, only monomers b1) are used in stage b).

[0066] A further polymerization of further ethylenically unsaturated monomers can be carried out after stage a) and before stage b). After stage b), further ethylenically unsaturated monomers can also be polymerized. Stage b) is preferably carried out immediately after stage a) and / or preferably no further polymerization reaction is carried out after stage b).

[0067] The weight parts of monomers and comonomers are selected to generally result in a glass transition temperature Tg of -65°C to +65°C, preferably -20°C to +20°C. The glass transition temperature Tg of the polymer can be determined in a known manner by differential scanning calorimetry (DSC). The approximate Tg can also be precalculated by the Fox equation. According to Fox TG, Bull. Am. Physics Soc. 1, 3, page 123 (1956): 1 / Tg = x1 / Tg1 + x2 / Tg2 + ... + xn / Tgn, wherein xn is the mass fraction (by weight % / 100) of monomer n, and Tgn is the glass transition temperature of the homopolymer of monomer n in Kelvin. The Tg values ​​of homopolymers are listed in Polymer Handbook 2nd Edition, J. Wiley & Sons, New York (1975).

[0068] The invention further provides a process for preparing multistage copolymers, preferably in the form of solid resins, by multistage free-radical initiated bulk or solution polymerization, characterized in that

[0069] a) in a first stage, copolymerizing one or more cyclic ketene acetal monomers a1) and one or more monomers a2) selected from the group consisting of vinyl esters of carboxylic acids having 1 to 15 carbon atoms, methacrylates or acrylates of carboxylic acids with unbranched or branched alcohols having 1 to 15 carbon atoms, olefins, dienes, vinyl aromatic compounds and halogenated olefins, and,

[0070] b) In a further stage, one or more ethylenically unsaturated monomers b1) carrying acid groups are polymerized in the presence of the copolymer from the first stage a).

[0071] Typically, stage a) and stage b) are polymerized by bulk and / or solution polymerization methods.

[0072] The polymerization temperature is preferably from 30 to 120° C., particularly preferably from 40 to 100° C., most preferably from 50 to 90° C. In the copolymerization of gaseous comonomers such as ethylene, the polymerization is preferably carried out at a pressure of typically 5 to 100 bar.

[0073] The polymerization can be initiated with initiators commonly used in bulk or solution polymerization processes, such as peresters, peroxydicarbonates, diacyl peroxides such as di-tert-amyl peroxyoxalate, tert-amyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-amyl peroxypivalate, tert-butyl peroxypivalate and dicyclohexyl peroxydicarbonate. The free radical initiators mentioned can also be optionally combined with a reducing agent in a known manner. For example, formaldehyde sulfoxylate salts or ascorbic acid are suitable. In the case of redox initiation, one or two redox catalyst components are preferably metered in during the polymerization. Preferably, the amount of the free radical initiator used is 0.005 mol% to 1 mol%, based on the comonomer phase.

[0074] During the polymerization, standard substances acting as chain transfer agents can be used to control the molecular weight. If chain transfer agents are used, they are usually used in an amount of 0.01% to 5.0% by weight, based on the monomer to be polymerized. Chain transfer agents are preferably metered in separately or premixed with the reaction components. Examples of chain transfer agents are n-dodecyl mercaptan, tert-dodecyl mercaptan, mercaptopropionic acid, methyl mercaptopropionate and acetaldehyde.

[0075] The monomers in stage a) can be initially charged completely or preferably partially, and any remaining amounts can be metered in during the polymerization.

[0076] The monomers of step b) are usually metered in after the monomers from step a) have been completely metered in. The metering of the monomers of stage b) is preferably started after the monomers of stage a) have been completely or substantially completely polymerized, in particular after a conversion of the monomers of stage a) of at least 85%, more preferably at least 90% and particularly preferably at least 95%.

[0077] Any emulsifier and any protective colloid can be initially added completely or preferably partially, and any remaining amount of emulsifier and / or protective colloid can be metered in during the polymerization. Suitable emulsifiers and / or protective colloids are described in detail below. Preferably, the polymerization is carried out in the absence of emulsifiers and / or protective colloids.

[0078] The multistage copolymers are preferably not emulsifier-stabilized and / or preferably not protective colloid-stabilized.

[0079] Bulk polymerization is typically conducted without added solvent or in the absence of solvent, ie, in bulk.

[0080] The solution polymerization is preferably carried out in one or more non-aqueous organic solvents, particularly preferably aprotic organic solvents such as esters, ethers or ketones. Esters are particularly preferred. The organic solvent preferably contains 1 to 12 carbon atoms and particularly preferably 1 to 8 carbon atoms. Examples of ethers are dioxane, tetrahydrofuran, diethyl ether, diisopropyl ether and diethylene glycol dimethyl ether. Examples of esters are ethyl acetate, butyl acetate, propyl propionate, ethyl butyrate and ethyl isobutyrate. Particularly preferred solvents are ethyl acetate and acetone. Preferably, no alcohol, in particular no methanol, ethanol, propanol, butanol and benzyl alcohol is used as solvent.

[0081] At the end of the polymerization, residual monomers can be removed by post-polymerization using known methods, for example by post-polymerization initiated by redox catalysts. Volatile residual monomers can also be removed by distillation, preferably under reduced pressure and optionally while passing an inert entraining gas such as air, nitrogen or water vapor through or over the mixture.

[0082] The multistage copolymers of stages a) and / or b) of the process according to the invention are preferably in the form of a melt, a solid resin or in the form of a solution or dispersion.

[0083] The mixture obtained by means of solution polymerization can be converted into a solid resin by standard methods, for example by precipitation, filtration and subsequent drying, or by separation by decantation and subsequent drying. Drying can be carried out in a known manner, for example in a drum dryer, in a flow tube, in a fluidized bed, or in a cyclone dryer.

[0084] The invention further provides a process for preparing multistage copolymers in the form of aqueous dispersions, characterized in that one or more multistage copolymers according to the invention are dispersed in water.

[0085] To prepare the multistage copolymers in the form of aqueous dispersions, it is generally possible to use the multistage copolymers in the form of solid resins or mixtures obtained by solution polymerization. It is also possible to convert the melt obtained by bulk polymerization directly into an aqueous dispersion.

[0086] The mixture obtained by means of solution polymerization can be mixed with water or added to water, for example, and the organic solvent can be removed subsequently, for example by distillation, optionally under reduced pressure, preferably as completely as possible. Multistage copolymers in the form of melts (obtained, for example, by bulk polymerization or by melting of solid resins) can be directly incorporated into water and dispersed, for example, under stirring, using conventional stirring units. Multistage copolymers in the form of solid resins can be directly dispersed in water, similar to the above description for the melt. These methods are particularly effective.

[0087] Alternatively, the multistage copolymer in solid resin or melt form can also be first dissolved with one or more organic solvents, preferably water-soluble solvents, such as alcohols (such as methanol or ethanol), ethers (such as THF), or in particular ketones (such as acetone), and then mixed with water or added to water, and the organic solvent can then be removed as completely as possible, for example by distillation, optionally under reduced pressure. These organic solvents generally have a lower boiling point than water, especially under the conditions prevailing during the solvent exchange process.

[0088] The mixing of the multistage copolymer with water and / or the dissolution of the solid resin in the organic solvent can generally be carried out at room temperature or elevated temperature, at ambient pressure or elevated pressure. Preferably, the dissolution is carried out at a pressure below the boiling point of the organic solvent at the pressure applied in the individual case.

[0089] To convert the multistage copolymers into aqueous dispersions, it is possible to use the apparatus customary for this purpose and standard mixing units, for example stirring units with high shear rates, such as Ultra-Turrax stirrers.

[0090] The multistage copolymer is preferably mixed with one or more bases. For example, the multistage copolymer in the form of an aqueous dispersion can be mixed with a base or preferably the multistage copolymer is mixed in an organic solvent. Inorganic bases or preferably organic bases can be used here. Examples of inorganic bases are alkali metal or alkaline earth metal hydroxides or ammonia, in particular sodium hydroxide or potassium hydroxide. Examples of organic bases are alkanolamines or alkyl or arylamines, in particular di- or trialkylamines. Preferred alkanolamines are dimethylethanolamine, ethanolamine, diethanolamine, triethanolamine, 2-aminomethylpropanol, diethylethanolamine, methyldiethanolamine, dimethylisopropylamine and dimethylisopropanolamine. Preferred alkyl or arylamines are trimethylamine, triethylamine, tributylamine, dibutylamine, dimethylaniline, diethylaniline or triphenylamine. The amount of base is preferably guided by the amount of ethylenically unsaturated monomers b1) with acid groups incorporated by polymerization. Based on the molar amount of monomer units b1) incorporated into the multistage copolymer by polymerization, preference is given to using 70 to 130 mol %, particularly preferably 80 to 120 mol %, of the base. Most preferably, an equimolar amount of the base is used, based on the molar amount of monomer units b1) incorporated into the multistage copolymer by polymerization. The molar amount of monomer units b1) incorporated by polymerization can be increased, for example, by 1 These measures make it possible, for example, to further improve the stability of aqueous dispersions of these multistage copolymers.

[0091] Preference is given to multistage copolymers in the form of solid resins, aqueous dispersions or water-redispersible powders which comprise one or more bases.

[0092] Alternatively, the addition of a base to the multistage copolymer may be omitted.

[0093] One or more emulsifiers and / or one or more protective colloids may be added to the multistage copolymer. This makes it possible to obtain, for example, more stable aqueous dispersions of the multistage copolymer or multistage copolymers in the form of aqueous dispersions with a higher solids content.

[0094] The emulsifier and / or protective colloid is preferably added to the multistage copolymer after its preparation by polymerization, particularly preferably to the mixture obtained by solution polymerization, or to a solution of the multistage copolymer in an organic solvent, or to an aqueous dispersion of the multistage copolymer.

[0095] Preference is given to multistage copolymers in the form of solid resins, in the form of aqueous dispersions or in the form of water-redispersible powders which comprise one or more emulsifiers and / or one or more protective colloids.

[0096] Examples of emulsifiers are in particular anionic and nonionic surfactants. Examples of anionic surfactants are alkyl sulfates with a chain length of 8 to 18 carbon atoms, alkyl and alkyl aryl ether sulfates with 8 to 18 carbon atoms and up to 40 ethylene oxide or propylene oxide units in the hydrophobic group, alkyl or alkyl aryl sulfonates with 8 to 18 carbon atoms, oleic acid sulfonates, esters and monoesters of sulfosuccinic acid with monohydric alcohols or alkylphenols. Suitable nonionic surfactants are, for example, alkyl polyglycol ethers or alkyl aryl polyglycol ethers with 8 to 40 ethylene oxide units. Preferably, alkyl ether sulfates or dodecylbenzene sulfonates are used.

[0097] Based on the dry weight of the multistage copolymers, preference is given to using up to 10% by weight, particularly preferably 0.1% up to 7% by weight and most preferably 1 to 4% by weight of one or more emulsifiers.

[0098] Examples of protective colloids are polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetals, polysaccharides, synthetic polymers such as poly(meth)acrylic acid, copolymers of (meth)acrylates with carboxyl-functional comonomer units, poly(meth)acrylamides, polyvinylsulfonic acid and water-soluble copolymers thereof, styrene-maleic acid and vinyl ether-maleic acid copolymers. Preferred protective colloids are polyvinyl alcohols, in particular partially hydrolyzed or fully hydrolyzed polyvinyl alcohols having a degree of hydrolysis of 80 mol % to 100 mol %. Particularly preferred are partially hydrolyzed polyvinyl alcohols having a degree of hydrolysis of 80 mol % to 95 mol % and having, in particular, a Höppler viscosity of 1 mPas to 30 mPas in a 4% aqueous solution (Höppler method at 20° C., DIN 53015). The protective colloids mentioned can be obtained by methods known to those skilled in the art.

[0099] The protective colloid is present in an amount of preferably 0.1 to 20% by weight, more preferably 0.1 to 15% by weight and particularly preferably 1 to 10% by weight, based on the dry weight of the multistage copolymer.

[0100] One or more additives can be added to the multistage copolymers to improve the performance properties, preferably after their preparation by polymerization, particularly preferably to the mixture obtained by solution polymerization, or to the solution of the multistage copolymer in an organic solvent, or to the aqueous dispersion of the multistage copolymer. Examples of additives are pigments, fillers, foam stabilizers, hydrophobizing agents or cement plasticizers.

[0101] These multistage copolymers in the form of aqueous dispersions have a solids content of preferably 5% to 75%, more preferably 10% to 70%, particularly preferably 20% to 60% and most preferably 30% to 50%.

[0102] The solids content of the multistage copolymer in the form of a protective colloid-free and emulsifier-free aqueous dispersion is preferably from 5% to 30%, particularly preferably from 6% to 20%, most preferably from 7% to 10%.

[0103] The multistage copolymers in the form of aqueous dispersions containing protective colloids or emulsifiers have a solids content of preferably >10% to 40%, particularly preferably 15% to 35% and most preferably 20% to 30%.

[0104] The multistage copolymer in the form of an aqueous dispersion containing protective colloid and emulsifier has a solids content of preferably 10% to 75%, particularly preferably 20% to 60% and most preferably 30% to 50%.

[0105] These multistage copolymers have a number average molecular weight of preferably from 5000 to 1,500,000 daltons, particularly preferably from 10,000 to 500,000 daltons and most preferably from 15,000 to 200,000 daltons.

[0106] The viscosity of the multistage copolymer in the form of an aqueous dispersion is preferably from 1 to 50,000 mPas, particularly preferably from 2 to 10,000 mPas, most preferably from 5 to 1000 mPas.

[0107] The particle size of the multistage copolymer is preferably 200 to 10,000 nm, more preferably 300 to 5,000 nm, particularly preferably 600 to 4,000 nm, and most preferably 1,000 to 3,000 nm.

[0108] Methods for determining solids content, molecular weight, viscosity and particle size are further described below in the Examples.

[0109] The present invention further provides a process for preparing a multistage copolymer in the form of a water-redispersible powder, characterized in that the aqueous dispersion of the multistage copolymer according to the invention is dried.

[0110] To prepare water-redispersible polymer powders, aqueous dispersions of multistage copolymers (polymer dispersions) are usually dried, optionally after adding protective colloids as drying aids, for example by fluidized bed drying, freeze drying or spray drying. The dispersion is preferably spray dried. Spray drying can be carried out in standard spray drying systems, wherein atomization can be carried out by one, two or multiphase nozzles or with a rotating disk. The outlet temperature is usually selected from 45° C. to 120° C., preferably 60° C. to 90° C., depending on the system, the Tg of the copolymer and the desired degree of drying. Examples of drying aids are the above-mentioned protective colloids, in particular polyvinyl alcohol. Typically, a drying aid (protective colloid) is used in a total amount of 3% to 30% by weight, in particular 5% to 20% by weight, based on the polymeric components of the dispersion.

[0111] In the spray for drying the aqueous polymer dispersion, a content of up to 3% by weight of defoamer, based on the base polymer, has proven to be advantageous in many cases. In order to increase the storability by improving the blocking stability, the polymer powder obtained can be provided, for example, with an antiblocking agent (anticaking agent), preferably up to 30% by weight, based on the total weight of the polymer components. Examples of antiblocking agents are calcium or magnesium carbonate, talc, gypsum, silicon dioxide, kaolin, metakaolin, calcined kaolin, silicates with a particle size preferably in the range of 10 nm to 100 μm.

[0112] The viscosity of the mixture to be dried is adjusted via the solids content so that a value of preferably <1500 mPas, particularly preferably <500 mPas is obtained (viscosity at 20 rpm and 25.0° C.). The solids content of the mixture to be dried is preferably >−35%, particularly preferably >−40%.

[0113] Further additives may be added during the drying process in order to improve the performance properties.Further ingredients present in the dispersed powder composition in the preferred embodiment are, for example, pigments, fillers, foam stabilizers, hydrophobizing agents or cement plasticizers.

[0114] The multistage copolymers, in particular in the form of aqueous dispersions, are generally suitable as binders for coating compositions or in particular as adhesives, for example for paints, fibers, textiles, leather, paper or carpets. It is also preferred to use the multistage copolymers as binders for bonding fiber materials, in particular for producing textile fabrics, such as nonwovens, knitted and woven fabrics, leather and fur, or carpets.

[0115] Furthermore, the multistage copolymers can also be used as additives for the preparation of shaped bodies, in particular as a component of a compound based on free-radically crosslinkable polymer compositions, such as unsaturated polyester resins (UP resins). Furthermore, the multistage copolymers can also be used as a chewing gum base in the production of chewing gum.

[0116] The multistage copolymers can also be used in construction chemicals. They can be used alone or in combination with conventional polymer dispersions or dispersion powders, optionally in combination with hydraulically setting binders such as cements (Portland cement, aluminate cement, pozzolanic cement, slag cement, magnesia cement, phosphate cement), gypsum and waterglass, for example for the production of leveling compounds, construction adhesives, renders, filling compounds, joint mortars, sealing slurries, thermal insulation composite systems or coatings, such as powder coatings. Among construction adhesives, tile adhesives or integrated thermal insulation adhesives are preferred areas of use. Preferred areas of application are also leveling compounds; preferred leveling compounds are self-leveling floor filling compounds and screeds.

[0117] Advantageously, the multistage copolymers of the invention can be very easily and to a large extent degraded biologically or under natural conditions. The term "biodegradable copolymers" generally means that these copolymers are completely or partially or proportionally biodegradable, that is to say under the action of microorganisms, or generally under natural conditions, in particular under the action of alkaline media; in particular, they have a better degradability than corresponding polymers comprising, for example, monomer units a2) and b1) but without monomer units a1).

[0118] Particularly surprisingly, using the method according to the invention, cyclic ketene acetal monomers can be incorporated into multistage copolymers by polymerization in high yields and the problem of hydrolysis of cyclic ketene acetal monomers during the preparation of polymer dispersions or during the incorporation of ethylenically unsaturated acids by polymerization can be at least reduced or even eliminated. The hydrolysis of cyclic ketene acetal monomers can be quantified, for example, by gas chromatography. According to the method according to the invention, the cyclic ketene acetal a1) according to the invention is advantageously selectively incorporated into the copolymer by ring opening, resulting in the formation of monomer units a1) of the formula 2 according to the invention. Side reactions, such as vinyl polymerization or elimination of polymerization, such as aldehydes or ketones, do not preferably occur to any significant extent. The polymer dispersions obtainable according to the invention are surprisingly stable, even without emulsifiers or protective colloids as stabilizers. Preferred embodiments of the invention make it possible to achieve these objects to a better extent.

[0119] Furthermore, the multistage copolymers exhibit surprisingly high levels of tack and, after application, surprisingly high adhesion and cohesion. DETAILED DESCRIPTION

[0120] The following examples are used to further illustrate the present invention:

[0121] The number-average molecular weight and mass-average molecular weight Mn, Mw as well as the polydispersity were determined by SEC (size exclusion chromatography):

[0122] The measurements were performed against polystyrene standards in THF at 35 °C at a flow rate of 0.3 ml / min and detection was performed with a RID (refractive index detector) on an Agilent PLgel MiniMIX-C Guard column with an injection volume of 20 µl.

[0123] Determination of the glass transition temperature Tg by DSC (Differential Scanning Calorimetry / Differential Thermal Analysis):

[0124] The measurements were carried out twice on a Metter Toledo DSC-1 apparatus in the temperature range of -150° C. to +150° C. with a heating or cooling rate of 10 K / min, the second run being used to determine the glass transition temperature.

[0125] Solid content of dispersion:

[0126] The solids content is determined on a Sartorius thermobalance. 1 g of the polymer sample is thinly applied onto an aluminum measuring plate and dried at 130° C. to constant weight.

[0127] Brookfield viscosity of dispersion:

[0128] The measurement was carried out on a Brookfield DV-II viscometer at 23° C. The measurement was carried out using spindle 1 or spindle 4 and a rotation speed of 20 rpm or 10 rpm, respectively.

[0129] Particle size distribution of dispersions by dynamic light scattering (DLS) (Z-average):

[0130] The particle size distribution was determined on a Malvern ZetaSizer Nano S with software version 2.2. The dispersion was diluted with demineralized water and measured at 20°C; the Z-average value (Dz) was calculated by the software. Detailed information on the calculation of Dz can be found under ISO 22412:2017 (Particle size analysis - Dynamic light scattering (DLS)).

[0131] Embodiment 1:

[0132] Acid-modified solid polyvinyl acetate resin containing MDO:

[0133] 241.3 g of ethyl acetate, 30.5 g of 2-methylene-1,3-dioxepane (MDO), 70.0 g of vinyl acetate (VAM) and 0.7 g of tert-butyl peroxypivalate (PPV, 75%) were introduced into a reactor and heated to 77°C.

[0134] A mixture of 7.5 g of ethyl acetate and 3.9 g of PPV (75%) was metered in over the course of 300 min.

[0135] 45 minutes after the start of the initiator metering, metering of a mixture of 81.3 g of MDO and 176.0 g of VAM was started and this mixture was metered in over the course of 220 minutes.

[0136] After the metered addition of the monomers was complete, 18.6 g of acrylic acid were metered in over 20 min, followed by dilution with 125.1 g of ethyl acetate metered in over 35 min. The mixture was kept under reflux for a further 60 min and then cooled to room temperature.

[0137] Residual monomers and solvents were removed by drying under reduced pressure.

[0138] The multistage copolymer obtained in the form of a solid resin had a glass transition temperature Tg of 2° C. and an average molecular weight Mw of 26 kDa.

[0139] Embodiment 2:

[0140] Secondary dispersion of the acid-modified MDO-containing solid resin from Example 1, without added emulsifier:

[0141] 25.5 g of a 20% solution of the solid resin from Example 1 in acetone were mixed with 0.35 ml of dimethylethanolamine. 55 g of water were added to the polymer solution under stirring. The dispersion thus obtained was sheared at 14 000 rpm for 15 min using an IKA Ultra-Turrax. The solvent was removed on a rotary evaporator and a stable secondary dispersion of the polymer was obtained.

[0142] The dispersion obtained had a solids content of 8.5%, a Brookfield viscosity of 9 mPas and an average particle size Dz of 1.003 nm.

[0143] Embodiment 3:

[0144] Secondary dispersion of the acid-modified MDO-containing solid resin from Example 1 with addition of a protective colloid:

[0145] 75 g of a 20% solution of the solid resin from Example 1 in acetone are admixed with 1.04 ml of dimethylethanolamine.

[0146] To the polymer solution was added a solution of 9.0 g of a 10% aqueous solution of polyvinyl alcohol (Mowiol 4-88) and 55 g of water with stirring.

[0147] The obtained dispersion was sheared using an IKA Ultra-Turrax at 14000 rpm for 15 min.

[0148] The solvent was removed on a rotary evaporator and a stable secondary dispersion of the polymer was obtained.

[0149] The dispersion obtained had a solids content of 20.3%, a Brookfield viscosity of 127 mPas and an average particle size Dz of 2.382 nm.

[0150] Embodiment 4:

[0151] Secondary dispersion of the acid-modified MDO-containing solid resin from Example 1, with addition of an emulsifier:

[0152] 75 g of a 20% solution of the solid resin from Example 1 in acetone are admixed with 1.04 ml of dimethylethanolamine.

[0153] A solution of 0.9 g of sodium dodecyl sulfate (SDS) and 50 g of water was added to the polymer solution under stirring.

[0154] The resulting dispersion was sheared at 10 000 rpm for 15 min using an IKA Ultra-Turrax. The number of revolutions was reduced here in order to reduce foam formation.

[0155] The solvent was removed on a rotary evaporator and a stable secondary dispersion of the polymer was obtained.

[0156] The obtained dispersion had a solids content of 26.3%, a Brookfield viscosity of 451 mPas, and an average particle size Dz of 1.251 nm.

[0157] Embodiment 5:

[0158] Secondary dispersion of the acid-modified MDO-containing solid resin from Example 1, with addition of emulsifier and protective colloid:

[0159] 950 g of a 20% solution of the solid resin from Example 1 in acetone are admixed with 13.2 ml of dimethylethanolamine.

[0160] An emulsifier solution containing 7.6 g of sodium lauryl sulfate and 76 g of a 10% aqueous solution of polyvinyl alcohol (Mowiol 4-88) and 250 g of water was added to the polymer solution under stirring.

[0161] The obtained dispersion was sheared using an IKA Ultra-Turrax at 14000 rpm for 15 min. The solvent was removed on a rotary evaporator and a stable secondary dispersion of the polymer was obtained.

[0162] The obtained dispersion had a solids content of 43.7%, a Brookfield viscosity of 151 mPas, and an average particle size Dz of 1.924 nm.

[0163] Comparative Example 6:

[0164] Non-acid modified solid polyvinyl acetate resin containing MDO:

[0165] 73.9 g of ethyl acetate, 15.1 g of 2-methylene-1,3-dioxepane (MDO), 35.1 g of vinyl acetate (VAM) and 0.2 g of tert-butyl peroxypivalate (PPV, 75%) were introduced into the reactor and heated to 77° C. A mixture of 2.3 g of ethyl acetate and 1.2 g of PPV (75%) was metered in over 300 min.

[0166] 45 min after the start of the initiator metering, metering of a mixture of 53.3 g of MDO and 124.5 g of VAM was started and this mixture was metered in over 240 min.

[0167] 15 min after the end of the metered addition of the monomers, dilution was carried out with 76.7 g of ethyl acetate, which was metered in over 45 min. The mixture was kept under reflux for a further 50 min and then cooled to room temperature.

[0168] Residual monomers and solvents were removed by drying under reduced pressure.

[0169] The polymer obtained had a glass transition temperature Tg of 0°C and an average molecular weight Mw of 43 kDa.

[0170] Comparative Example 7:

[0171] Attempt to disperse the non-acid-modified MDO-containing solid resin from Comparative Example 6, adding emulsifier and protective colloid:

[0172] An emulsifier solution containing 0.6 g of sodium dodecyl sulfate and 6 g of a 10% aqueous solution of polyvinyl alcohol (Mowiol 4-88) and 20 g of water was added to 75 g of a 20% solution of the solid resin from Comparative Example 6 in acetone under stirring.

[0173] The resulting mixture was sheared using an IKA Ultra-Turrax at 14000 rpm for 15 min.

[0174] The solvent was removed on a rotary evaporator, wherein the polymer precipitated as a precipitate and no dispersion was obtained.

[0175] Comparative Example 8:

[0176] Attempt to disperse the non-acid modified MDO-containing solid resin from Comparative Example 6, adding emulsifier and polyacrylic acid:

[0177] To 50 g of a 20% solution of the solid resin from Comparative Example 6 in acetone was added, under stirring, an emulsifier solution comprising 0.4 g of sodium dodecyl sulfate, 4 g of a 10% aqueous solution of polyvinyl alcohol (Mowiol 4-88), 500 mg of polyacrylic acid (Mw=1800 g / mol), and 0.69 ml of dimethylethanolamine and 13 g of water.

[0178] The obtained dispersion was sheared using an IKA Ultra-Turrax at 14000 rpm for 15 min.

[0179] The solvent was removed on a rotary evaporator, wherein the polymer precipitated as a precipitate and no dispersion was obtained.

[0180] Comparative Example 9:

[0181] MDO emulsion polymerization attempt (recreation of ACS Macro Lett. 2021, 10, 5, pages 591 to 597):

[0182] 16.7 g of Disponil FES 32, 25 mg of FeSO4.7H2O in 16 ml of water, and 3.5 g of 1% aqueous EDTA and 0.06 ml of 2M sodium hydroxide solution were added to 310 ml of water and the pH was adjusted to 8 by addition of 25% aqueous ammonium hydroxide. The reaction vessel was heated to 40°C.

[0183] A mixture of 173.0 g of vinyl acetate (VAM) and 43.9 g of 2-methylene-1,3-dioxepane (MDO) was metered in over a period of 60 min.

[0184] A mixture of 46.4 g of water, 1.4 g of a 50% aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 1.6 g of a 70% aqueous solution of Tergitol and 6.2 g of Disponil FES 32 was metered in simultaneously over the course of 60 min.

[0185] An initiator phase consisting of 1.4 g ammonium peroxodisulfate, 0.64 g tert-butyl hydroperoxide (tBHP) and 38.6 g water and a reducing phase consisting of 2.6 g FF6 in 37.6 g water were metered in over 70 min, while the monomers were metered in. The polymerization was carried out at 40 ° C. The pH was maintained at 8 by adding 25% aqueous ammonium hydroxide solution.

[0186] The obtained dispersion had an average particle size of 164 nm and a solids content of 30.7%.

[0187] The crude dispersion in CDCl3 1 The H NMR contains a triplet at 4.05 ppm which is characteristic of the hydrolysis product of MDO, 4-hydroxybutyl acetate. This can also be detected in the dispersion by gas chromatography.

[0188] pass 1 Drying of the dispersion and re-examination of the obtained solid by H NMR showed that the polymer consisted of polymerized MDO (triplet at 3.95 ppm in CDCl3) to an extent of only 1.9 mol% (theoretical: 16.1 mol%).

[0189] Comparative Example 10:

[0190] An attempt was made to prepare a crotonic acid-modified solid polyvinyl acetate resin containing MDO by metering acid monomer and MDO simultaneously:

[0191] 75.6 g of ethyl acetate, 2.6 g of 2-methylene-1,3-dioxepane (MDO), 48.8 g of vinyl acetate (VAM), 1.6 g of crotonic acid and 0.2 g of tert-butyl peroxypivalate (PPV, 75%) were introduced into a reactor and heated to 77°C.

[0192] A mixture of 2.4 g of ethyl acetate and 1.23 g of PPV (75%) was metered in over the course of 300 min.

[0193] 45 min after the start of the initiator metering, metering of a mixture of 9.1 g of MDO, 10.8 g of crotonic acid and 172.9 g of VAM was started and metered in over 240 min. After the metering was complete, the mixture was kept under reflux for a further 60 min and then cooled to room temperature.

[0194] Residual monomers and solvents were removed by drying under reduced pressure.

[0195] The obtained polymer had a glass transition temperature Tg of 42°C and an average molecular weight Mw of 58 kDa. 1HNMR spectroscopy did not detect any binding of MDO.

[0196] Comparative Example 11:

[0197] Attempt to prepare an acid-modified solid polyvinyl acetate resin containing MDO in methanol:

[0198] 112.7 g of methanol, 14.2 g of 2-methylene-1,3-dioxepane (MDO), 30.8 g of vinyl acetate (VAM) and 0.3 g of tert-butyl peroxypivalate (PPV, 75%) were introduced into a reactor and heated to 77°C.

[0199] A mixture of 3.5 g of ethyl acetate and 1.8 g of PPV (75%) was metered in over 300 min.

[0200] 45 minutes after the start of the initiator metering, metering of a mixture of 37.9 g of MDO and 82.2 g of VAM was started and this mixture was metered in over the course of 220 minutes.

[0201] After the metered addition of the monomers had ended, 8.7 g of acrylic acid were metered in over the course of 20 minutes, followed by dilution with 58.4 g of methanol metered in over the course of 35 minutes.

[0202] The mixture was kept at reflux for an additional 60 min and then cooled to room temperature.

[0203] Residual monomers and solvents were removed by drying under reduced pressure.

[0204] The obtained polymer had a glass transition temperature Tg of 41°C and an average molecular weight Mw of 25 kDa. 1 HNMR spectroscopy did not detect any binding of MDO.

[0205] Embodiment 12:

[0206] Acid-modified solid polyvinyl acetate resin containing MDO:

[0207] 591 g of ethyl acetate, 135 g of 4-methylene-1,3-dioxepane (MDO), 187.0 g of vinyl acetate (VAM) and 1.3 g of tert-butyl peroxypivalate (PPV, 75%) were introduced into the reactor, and an equivalent of 147 g of ethylene was injected. The mixture was then heated to 77°C.

[0208] A mixture of 31 g of ethyl acetate and 16 g of PPV (75%) was metered in over the course of 300 min.

[0209] 45 minutes after the start of the initiator metering, the metering of a mixture of 397 g of MDO and 727 g of VAM was started and this mixture was metered in over 220 minutes.

[0210] After the metered addition of the monomers was complete, 93 g of acrylic acid were metered in over 20 min, followed by dilution with 713 g of ethyl acetate metered in over 45 min. The mixture was kept under reflux for a further 50 min and then cooled to 30°C.

[0211] Residual monomers and solvents were removed by drying under reduced pressure.

[0212] The multistage copolymer obtained in the form of a solid resin had a glass transition temperature Tg of -15°C and an average molecular weight Mw of 33 kDa.

[0213] Embodiment 13:

[0214] Secondary dispersion of the acid-modified MDO-containing solid polyvinyl acetate resin from Example 12 with addition of emulsifier and protective colloid:

[0215] 500 g of a 20% solution of the solid resin from Example 12 in acetone are admixed with 7.0 ml of dimethylethanolamine.

[0216] An emulsifier solution containing 4.0 g of sodium lauryl sulfate, 40 g of a 10% aqueous solution of polyvinyl alcohol (Mowiol 4-88) and 130 g of water was added to the polymer solution under stirring.

[0217] The obtained dispersion was sheared using an IKA Ultra-Turrax at 14000 rpm for 15 min. The solvent was removed on a rotary evaporator and a stable secondary dispersion of the polymer was obtained.

[0218] The obtained dispersion had a solids content of 37.6%, a Brookfield viscosity of 26.340 mPas, and an average particle size Dz of 1.114 nm.

[0219] Comparative Example 14:

[0220] An attempt was made to prepare an acrylic acid-modified solid polyvinyl acetate resin containing MDO by metering acid monomer and MDO simultaneously:

[0221] 60.3 g of ethyl acetate, 7.6 g of 2-methylene-1,3-dioxepane (MDO), 16.5 g of vinyl acetate (VAM) and 0.2 g of tert-butyl peroxypivalate (PPV, 75%) were introduced into the reactor and heated to 77° C. A mixture of 3.5 g of ethyl acetate and 1.0 g of PPV (75%) was metered in over 300 min.

[0222] 45 minutes after the start of the initiator metering, the metering of a mixture of 20.3 g of MDO, 4.7 g of acrylic acid and 44.0 g of VAM was started and this mixture was metered in over 240 minutes.

[0223] After the metered addition of the monomers had ended, dilution was carried out with 34.7 g of ethyl acetate, which was metered in over 45 min. The mixture was kept under reflux for a further 60 min and then cooled to room temperature.

[0224] Residual monomers and solvents were removed by drying under reduced pressure.

[0225] The obtained copolymer in the form of a solid resin had a glass transition temperature Tg of 17.9° C. and an average molecular weight Mw of 39 kDa. 1 H NMR spectroscopy was only able to detect a partial MDO incorporation of 7.9 mol % (theory: 24.2 mol %).

[0226] Comparative Example 15:

[0227] An attempt was made to prepare an acrylic acid-modified, MDO-containing solid polyvinyl acetate resin with parallel metering of acid monomer and MDO:

[0228] 60.3 g of ethyl acetate, 7.6 g of 2-methylene-1,3-dioxepane (MDO), 16.5 g of vinyl acetate (VAM) and 0.2 g of tert-butyl peroxypivalate (PPV, 75%) were introduced into the reactor and heated to 77° C. A mixture of 3.5 g of ethyl acetate and 1.0 g of PPV (75%) was metered in over 300 min.

[0229] 45 minutes after the start of the initiator metering, metering of a mixture of 20.3 g of MDO and 44.0 g of VAM was started and the mixture was metered in over 240 minutes. In parallel therewith, 4.7 g of acrylic acid were metered in over 240 minutes from a separate storage container.

[0230] After the metered addition of the monomers had ended, dilution was carried out with 34.7 g of ethyl acetate, which was metered in over 45 min. The mixture was kept under reflux for a further 60 min and then cooled to room temperature.

[0231] Residual monomers and solvents were removed by drying under reduced pressure.

[0232] The obtained copolymer in the form of a solid resin had a glass transition temperature Tg of 16.4° C. and an average molecular weight Mw of 33 kDa. 1 H NMR spectroscopy was only able to detect a partial MDO incorporation of 8.8 mol % (theory: 24.2 mol %).

Claims

1. A multistage copolymer obtainable by multistage, free-radical initiated bulk or solution polymerization, characterized in that a) in a first stage, copolymerizing one or more cyclic ketene acetal monomers a1) and one or more monomers a2) selected from the group consisting of vinyl esters of carboxylic acids having 1 to 15 carbon atoms, methacrylates or acrylates of carboxylic acids with unbranched or branched alcohols having 1 to 15 carbon atoms, olefins, dienes, vinyl aromatic compounds and halogenated olefins, and, b) In a further stage, one or more ethylenically unsaturated monomers b1) carrying acid groups are polymerized in the presence of the copolymer from the first stage a).

2. The multistage copolymer according to claim 1, characterized in that The multistage copolymer is in the form of a solid resin, a water dispersion or a water-redispersible powder.

3. The multistage copolymer according to claim 1 or 2, characterized in that: One or more cyclic ketene acetal monomers a1) are compounds of the general formula 1 (1), Where n=0, 1, 2 or 3; R is a hydrogen atom or a C1-C6 alkyl group; R 1 and R 2 are independently a hydrogen atom or a C1-C 12 an alkyl, phenyl, vinyl or halogen group; or R 1 and R 2 Together with the carbon atoms to which they are bonded, they form a fused benzene ring or a fused C3-C7 alicyclic ring; and R 1’ and R 2’ are independently a hydrogen atom or a C1-C 12 an alkyl, phenyl, vinyl or halogen group; or R 1 and R 1’ and / or R 2 and R 2’ forming an exocyclic double bond; and R 3 and R 3’ are independently a hydrogen atom or a C1-C 12 an alkyl, phenyl, vinyl or halogen group; or R 3 and R 3’ forming an exocyclic double bond or a spirocycloaliphatic group or a spiro-2-methylene-1,3-dioxepanyl group; or R 3 and R 3’ The carbon atoms to which they are bonded form an internal double bond, a fused benzene ring, or a fused C3-C7 alicyclic ring; Wherein one or more -(CR 3 R 3’ ) groups are each replaced by an oxygen atom.

4. The multistage copolymer according to claims 1 to 3, characterized in that The one or more cyclic ketene acetal monomers a1) are selected from the group consisting of 2-methylene-1,3-dioxolane, 2-methylene-4-methyl-1,3-dioxolane, 2-methylene-4,5-dimethyl-1,3-dioxolane, 8-methylene-7,9-dioxabicyclo[4.3.0]nonane, 2-methylene-1,3-dioxane, 2-methylene-5-methyl-1,3-dioxane, 2-methylene-5,5-dimethyl-1,3-dioxane, 2-methylene-1,3-dioxane 2-Methylene-1,3-dioxolane-5-spirocyclopentane, 2-Methylene-1,3-dioxepane, 2-Methylene-1,3-dioxocane, 2-Methylene-4-phenyl-1,3-dioxolane, 4,7-dimethyl-2-methylene-1,3-dioxepane, 5,6-benzo-2-methylene-1,3-dioxepane, 2-Methylene-1,3,6-trioxocane and 2-Methylene-1,3,5-trioxane.

5. The multistage copolymer according to claims 1 to 4, characterized in that The cyclic ketene acetal monomer a1) is 2-methylene-1,3-dioxepane.

6. The multistage copolymer according to claims 1 to 5, characterized in that The multistage copolymer is based on cyclic ketene acetal monomers a1) to an extent of 20 to 70% by weight, based on the total weight of the monomers of step a).

7. The multistage copolymer according to claims 1 to 6, characterized in that The multistage copolymer is based on monomers a2) to an extent of 30 to 80% by weight, based on the total weight of the monomers of step a).

8. The multistage copolymer according to claims 1 to 7, characterized in that The one or more ethylenically unsaturated monomers b1) carrying acid groups are selected from the group comprising ethylenically unsaturated carboxylic acids, ethylenically unsaturated acid anhydrides, ethylenically unsaturated phosphoric acids, ethylenically unsaturated sulfonic acids, ethylenically unsaturated sulfuric acids, or salts thereof.

9. The multistage copolymer according to claims 1 to 8, characterized in that The multistage copolymer is based on monomers b1) to an extent of 0.5 to 15% by weight, based on the total weight of the monomers of step a).

10. The multistage copolymer according to claims 1 to 9, characterized in that The multistage copolymer is based on monomers b1) to an extent of 25 to 100% by weight, based on the total weight of the monomers of step b).

11. The multistage copolymer according to claims 1 to 10, characterized in that In stage b), exclusively monomers b1) are used as ethylenically unsaturated monomers.

12. A method for preparing the multistage copolymers according to claims 1 to 11 by multistage, free radical initiated bulk polymerization or solution polymerization, characterized in that a) in a first stage, copolymerizing one or more cyclic ketene acetal monomers a1) and one or more monomers a2) selected from the group consisting of vinyl esters of carboxylic acids having 1 to 15 carbon atoms, methacrylates or acrylates of carboxylic acids with unbranched or branched alcohols having 1 to 15 carbon atoms, olefins, dienes, vinyl aromatics and halogenated olefins, b) In a further stage, one or more ethylenically unsaturated monomers b1) carrying acid groups are polymerized in the presence of the copolymer from the first stage a).

13. The method for preparing a multistage copolymer according to claim 12, characterized in that: The polymerization is carried out in the absence of emulsifiers and / or protective colloids.

14. A process for preparing a multistage copolymer in the form of an aqueous dispersion, characterized in that The multistage copolymer is prepared according to claim 12 or 13 and dispersed in water.

15. The method for preparing a multistage copolymer according to claims 12 to 14, characterized in that The multistage copolymer is mixed with one or more organic or inorganic bases.

16. The method for preparing a multistage copolymer according to claims 12 to 15, characterized in that One or more emulsifiers and / or one or more protective colloids are added to the multistage copolymer.

17. Use of the multistage copolymers according to claims 1 to 11 as binders in coating compositions or adhesives, in particular for paints, textiles, paper or carpets, or in construction chemicals.

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