摘要:
Silane-modified polyvinyl acetals are obtained by copolymerizing a) vinyl esters of C1-15 alkylcarboxylic acids having from 1 to 15 carbon atoms, and optionally (meth)acrylates C1-15 of alcohols, olefins, dienes, vinylaromatics, or vinyl halides, with b) from 0.02 to 20.0 % by weight of an ethylenically unsaturated, hydrolyzable silicon compounds or hydrolyzable mercaptosilanes; hydrolyzing the resulting vinyl ester copolymers to 50 mol % or more of vinyl alcohol units; and acetalizing vinyl alcohol units with a C1-15 aliphatic or aromatic aldehydes, wherein from 5 to 50 % by weight of a mixture of comonomers a) and silane comonomers b), based on the total weight of comonomers a) and b), is used as an initial charge, and the remainder is metered in during polymerization, such that the ratio between the comonomers a) and silane comonomers b) remains constant throughout the polymerization, resulting in a homogeneous polymer.
摘要:
The invention relates to silane-modified polyvinyl acetals obtained by acetalizing partially hydrolyzed or fully hydrolyzed vinyl ester polymers having at least 50 mol % of vinyl alcohol units with one or more aldehydes, optionally in the form of their hemiacetals or their acetals, where at least one aldehyde contains hydrolyzable silane groups.
摘要:
The invention relates to a method for producing polyvinylacetals that can be obtained by saponifying a vinylester polymer and subsequently acetalizing the polyvinyl alcohol, which is obtained therewith, with one or more aldehydes selected from the group consisting of aliphatic and aromatic aldehydes having 1 to 15 C atoms, whereby: a) the polyvinyl alcohol is present in an aqueous medium; b) a pH value of
摘要:
Polyvinyl acetals are obtained in a cost-effective and environmentally advantageous manner by employing as at least a portion of the aqueous acetalization medium, the mother liquor from a previous acetalization reaction.
摘要:
Low molecular weight polyvinyl acetals have a solution viscosity of from 2 to 12 mPas and a degree of polymerization Pw less than 200, and are obtained by hydrolyzing a vinyl ester polymer having a solution viscosity of from 1.0 to 1.6 mPas until the content of vinyl alcohol units is ≧50 mol %, to produce a polyvinyl alcohol whose solution viscosity is from 1.0 to 2.0 mPas, and then acetalizing the resultant polyvinyl alcohol. The products may be used as binders and films of increased adhesion to substrates.
摘要:
Low shear-thinning polyvinyl acetals having a solution viscosity in 30% strength by weight solution in methyl ethyl ketone which changes by not more than 10% in a shear rate range from 1 to 100 s−1. The preparation of the low shear-thinning polyvinyl acetals involves acetalation of partly hydrolyzed or completely hydrolyzed vinyl ester polymers comprising ≧50 mol % of vinyl alcohol units with one or more aldehydes, optionally in the form of the hydrates, hemiacetals or full acetals, wherein from 0 to 60% by weight of the aldehyde, based on the total amount of the aldehyde, is initially introduced over the course of the first one to ten minutes of the acetalation and is prereacted over the course of from 1 to 30 minutes, and the remaining proportion is then metered in continuously over the course of at least 20 minutes.
摘要:
A process for preparing silicone-containing polymers comprises free-radical polymerization of one or more ethylenically unsaturated organic monomers in the presence of copper-free free-radical initiator and one or more polymerization regulators, wherein a polymerization regulator is a silicone which contains at least one aldehyde group.
摘要:
Organosilicone and vinyl ester copolymers free from phase separation are prepared by copolymerizing at least one vinyl ester monomer with organosilicones containing difunctional silicone monomers and optionally a minor amount of monofunctional silicone monomers, in a non-aqueous solvent mixture containing at least one solvent with a transfer coefficient greater than 20·10−4 relative to vinyl acetate.
摘要:
Polymer dispersions of polymers derived from silicone macromers and ethylenically unsaturated monomers are capable of incorporating large amounts of chemically bonded macromer, when the silicone macromer and part of the unsaturated monomer are polymerized in aqueous medium as an initial charge with an oil soluble initiator, and the remaining monomers are fed in and polymerized using a water soluble initiator. The dispersions may be dried to form water redispersible polymer powders.
摘要:
Thermoplastic silicon block copolymers containing (A) a hard segment polymer constituent prepared from styrene, methylmethacrylate, butylacrylate, acrylonitrile, vinyl monomers, or mixtures therefore, and (B) a soft segment polymer constituent of general formula (I) G-[(SiR2O)mSiR2—X—]n(SiR2O)mSiR2-G wherein R is an optionally halogenated monovalent C1-18 hydrocarbon radical and X is a specific aryl group-containing, silicon bonded radical, and each G may be a radical (A)-Z-(Si) or Z′-(Si) wherein -Z- represents an aryl group-containing bivalent radical and Z′- represents a monovalent aryl group-containing radical, provided that there is, at most, one radical G and one radical Z′- in formula (I). In formula (I), m represents a whole number between 1 and 1000 and n represents 0 or a whole number between 1 and 20, provided that when n does not equal 0, 4≦n·m≦1000.