Showing papers on "Vinyl acetate published in 1992"

Catalysts and processes for the manufacture of vinyl acetate

Abstract: A shell impregnated catalyst for use in the production of vinyl acetate from ethylene, acetic acid and an oxygen containing gas is provided. The catalyst has a productivity of greater than 661 grams of vinyl acetate per hour per liter of catalyst at 150° C. and consists essentially of: (1) a catalyst support having a particle diameter from about 3 to about 7 mm and a pore volume of 0.2 to 1.5 ml per gram (2) palladium and gold distributed in the outermost 1.0 mm thick layer of the catalyst support particles, and (3) from about 3.5 to 9.5% by weight of potassium acetate. The catalyst is characterized by having a gold to palladium weight ratio in the range 0.60 to 1.25.

Graft polymers of natural substances containing saccharide structures or derivatives thereof and ethylenically unsaturated compounds and their use

Abstract: (1) Graft polymers (I) obtainable by polymerisation of (A) monomers or monomer mixts. comprising (A1) 10-100 % (all pts. wt.) N-vinylcarboxylic amides. CH2=CH-N(R2)C(O)R' (1), where R1, R2 = H or 1-6 C alkyl (A2) 0-90 % other monoethylenically unsatd., carboxylic gp.-free monomer copolymerisation with (A1) (A3) 0-5 % monomer with at least 2 ethylenically unsatd., non-conjugated double bonds in mol. in presence of (B) mono-, oligo-, or poly-saccharide; oxidatively, hydrolytically, or enzymatically degraded polysaccharide; oxidatively-hydrolytically or oxidatively-enzymatically degraded polysaccharide; chemically modified mono-, oligo-, or poly-sacchardie, or mixt. of these in ratio (A):(B) = 95-20:5-80 and op. subsequent splitting off of gp. -C(:O)R1 from polymerised monomers (A) of (I) with formation of units -CH2-CNHR2H- are claimed. (2) Also claimed are (I) obtainable by process wherein mixt. of 1-99 % N-vinylformamide (II) and 99-1 % vinyl acetate (III) is used as (A), 2-100 % formyl gps. of polymerised (II) are split off with formation of units -CH2-C(NH2)H- (3) and 2-100 % acetate gps. of polymerisated (III) and split off with formation of units -CH20C(OH)H- (4). USE/ADVANTAGE - Dry- and wet-stength agents in prepn. of paper, carboard, and paperboard, (I), prepd. partly with renewable raw materials, are less expensi

Dynamic studies of the molecular relaxations and interactions in microcomposites prepared by in-situ polymerization of silicon alkoxides

Abstract: In-situ polymerization of silicon alkoxide was used to prepare composites of silicon dioxide and poly(vinyl acetate) (PVAc). The FTIR, dielectric, and dynamic mechanical spectroscopy results showed that β decreased with increasing sol-gel concentration, indicating that there is a broadening in the distribution of relaxation times for PVAc chains. The results suggested that thereexists an interfacial region in the composidtes where the mobility of the PVAc is reduced by the interactions with the silicate network.

Size effects on solvent diffusion in polymers

Abstract: Capillary column inverse gas chromatography (CCIGC) has been used for the measurement of diffusion coefficients in polymer-solvent systems at conditions approaching on a solvent diffusion in two polymers, poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc, measuremnets of diffusion coeffiients were made at temperatures ranging from T g to 70 K above T g . Over 30 solvents were evaluated: alkanes, alkenes, aromatic hydrocarbons, and aliphatic esters.

Asymmetric hydroformylation of vinyl acetate by use of chiral bis(triarylphosphite)-rhodium(I) complexes

Abstract: Bis(triarylphosphite) ligands 1–4 were prepared in optically pure forms from (R)- or (S)-binaphthol and (ArO) 2 PCl, and their Rh(I) complexes have been used as catalysis for hydroformylation of vinyl acetate. The corresponding branched aldehyde, 2-acetoxypropanal, was given in up to 95% regioselectivity and in 49% ee.

Emulsion polymerization of vinyl acetate using a polymerizable surfactant. I. Kinetic studies

Abstract: A polymerizable surfactant, sodium dodecyl ally sulfosuccinate (TREM LF-40; Henkel) and its nonpolymerizable counterpart were used in comparative studies of the emulsion polymerization on vinyl acetate. The conversion-time behavior differed for the two-surfactants; the TREM LF-40 showed a decrease in the polymerization rate with increasing concentration while its hydrogenated derivative showed the opposite behavior, the rate increasing with increasing surfactant. Particle size decreased with increassing surfactant concentration for both series of reactions. An explanation for the seemingly ambiguous results obtained for the polymerizable surfactant was sought

Lipase-catalyzed kinetic resolution of .gamma.-hydroxy phenyl sulfones

Abstract: Lipase PS (from Pseudomonas cepacia) catalyzed the enantioselective transesterification of racenic γ-hydroxy- α,β-unsaturated phenyl sulfones 1 and their α,β-saturated derivatives 3 with vinyl acetate in an organic solvent (usually i Pr 2 O). Remarkably, in substrates 1 with (E)-stereochemistry, the enantioselectivity of the process was little influenced by the nature of the R chain. Hence, very high enantiomeric ratios (E≥45) were observed in substrates 1 bearing short (R=Me or Et)

Water sensitive hot melt adhesives for nonwoven applications

Abstract: Nonwoven assemblies bonded with water dispersible or sensitive hot melt adhesives comprising 50-100 parts of a graft copolymer of about 40-85% of at least one vinyl monomer and about 15-60% of at least one water soluble polyalkylene oxide polymer, and about 0-50 parts by weight of tackifying resin. The compositions may also be employed as water sensitive binders in the manufacture of the nonwoven. Vinyl acetate is the preferred vinyl monomer whereas ethylene oxide homo- or copolymers are the preferred polyalkylene oxide. The use of tackifying resin is optional and may be undesirable for many of the applications.

Carrier catalyst, process for its preparation, and its use for the preparation of vinyl acetate

Abstract: The invention relates to a process for the preparation of a catalyst which contains palladium and/or compounds thereof and alkali metal compounds, and additionally cadmium compounds and/or gold and/or compounds thereof, on support particles which have been pressed from SiO2 or an iO2 -Al2 O3 mixture with the aid of a binder which comprises a) washing the roasted support particles with an acid which does not react with SiO2 or SiO2 -Al2 O3 mixtures, until no further cations of the binder employed during pressing of the support particles are released from the support particles; b) then impregnating the support particles with palladium, and gold or cadmium; c) then bringing the impregnated support particles into contact with a solution of a base at least until the thickness of the nobel metal shell generated in this way on the support particles no longer changes substantially; and d) then impregnating the support particles with an alkali metal compound. A shell-like distribution of the palladium and if appropriate of the gold in the support particles is generated in this manner. Furthermore, the invention relates to a catalyst prepared in this way and to its use for the preparation of vinyl acetate.

Reaction kinetics of DNA-histone crosslinking by vinyl acetate and acetaldehyde.

Abstract: The formation and stability of DNA-protein crosslinks (DPXLs) formed by incubation of pUC13 plasmid DNA and calf thymus histones with 1-100 mM acetaldehyde was studied using a filter binding assay. DPXLs were formed at a rate of 127 DPXLs/plasmid molecule/mmol acetaldehyde in a reaction containing 1 microgram of histones and 0.33 microgram of DNA at 37 degrees C for 1 h. Acetaldehyde-induced DPXLs were unstable at 37 degrees C, with loss of up to 75% by 8 h. Crosslink formation was significantly higher at lower pH, with 3- and 2-fold higher levels at pH 5 and 6 respectively than at pH 7.5. Induction of DPXL formation by 1-100 mM vinyl acetate in the presence of rat liver microsomes was observed at 37 degrees C over 3 h. DPXL accumulation followed S-phase enzymatic kinetics, with a rate of formation of 1.1 DPXLs/plasmid molecule/mmol vinyl acetate/microgram microsomal protein/microgram DNA. Vinyl acetate was unable to cause formation of DPXLs in the absence of microsomes. A carboxylesterase inhibitor, bis-(p-nitrophenyl) phosphate, was able to block DPXL formation by vinyl acetate and microsomes. This work supports the hypothesis that DPXL formation by vinyl acetate requires microsomal metabolism to acetaldehyde, which is the active crosslinking agent.

Halogen-free floor covering

Abstract: A surface covering including a blend of a silane-grafted ethylene/vinyl acetate polymer and an ungrafted thermoplastic polymer retains the desirable balance between indentation, tensile strength and elongation of a fully grafted EVA while permitting the reprocessibility of scrap material. Preferably, the silane graft density is one graft per about 100 carbons to one graft per about 5,000 carbons. The preferred EVA has about 18% to about 28% vinyl acetate.

Temporal Stability of Polar Organic Compounds in Stainless Steel Canisters

Abstract: Because of considerable interest at US EPA for the collection of polar organic compounds in stainless steel canisters, particularly for the Toxic Air Monitoring Site (TAMS) study, the stability of 10 selected polar organics in canisters was investigated and the results are described in this paper. The polar organic compounds selected for this stability study were: methanol, acetone, isoprene, acrylonitrile, vinyl acetate, methyl ethyl ketone, t-butyl methyl ether, ethyl acetate, n-butanol, and ethyl acrylate. Two nonpolar compounds, methyl chloroform and toluene, shown to be stable in previous work were included in the stability study as controls. The compounds were loaded in unpolished and Summa-polished canisters at parts-per-billion (ppb) levels under dry and humid conditions. The canister samples were analyzed on Days 0, 1, 3, 4, 14, and 31 after loading. The experimental procedures and stability results are summarized briefly.

Emulsion polymerization of vinyl acetate using a polymerizable surfactant. II. Polymerization mechanism

Abstract: The mechanism of growth of latex particles in the emulsion polymerization of vinyl acetate using a polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40; Henkel) was investigated. Both the aqueous phase and the particle/water interface were found to be loci for the copolymerization of TREM LF-40 with vinyl acetate. The results suggest that the reactions at the particle/water interface are more important and that the particlesize of the latices is a key parameter controlling the polymerization rate through copolymerization and chain transfer to the polymerizable surfactant at the particle surface

Biaxially oriented copolyester film primed with vinyl acetate polymers

Abstract: The invention concerns a primer coated, biaxially oriented self-supporting mono- or multilayer copolyester film, wherein the copolyester is PENBB and wherein the primer coating contains a vinyl acetate copolymer. PENBB is a copolyester containing units of formula (I).

Hair treatment composition

Abstract: A hair treatment composition is provided that includes a water-insoluble, dispersible polymeric resin having a viscosity of less than 2 centipoise at 25° C when dispersed at 10% in water; a water-soluble polymeric resin having a viscosity greater than 6 centipoise at 25° C when 10% is placed in water; and a water-soluble polymer of molecular weight greater than about 500,000 Illustrative of the water-insoluble resin is a diglycol/cyclohexanedimethanol/isophthalates/sulfoisophthalates polyester Preferably the water-soluble polymeric resin is a copolymer of polyvinyl-pyrrolidone and vinyl acetate The preferred water-soluble polymer is polyvinylpyrrolidone, especially a polymer having molecular weight of around 630,000

Complex formation between pairs of vinyl polymers

Abstract: The coefficient of interaction k AB between three pairs of polymers, poly(vinyl acetate) (PVAc) and polyacrylonitrile, PVAc and poly(methyl methacrylate), and PVAc and poly(methacrylic acid) was determined at 60°C in ternary solutions consisting of two polymers in DMSO, DMF, and dioxane. In these systems, where interpolymer complexes are formed, the k Ab value is extremely high and it is a direct function of the polarity of the solvent. The high values indicate that a strong interaction, which consists of van der Waals forces and hydrogen bonding, exists between the polymers.

New crystal of dichloro-tin phthalocyanine, its production and electophotgraphic photoreceptor and coating fluid for the photoreceptor which are made therefrom

Abstract: PURPOSE:To provide new crystals of dichloro-tin phthalocyanine, useful as a charge generating material, a method for producing the crystals. an electrophotographic photoreceptor having high sensitivity and durability. and a coating fluid for an electrophotographic photoreceptor, which enables the dichloro-tin phthalocyanine crystals to maintain the original crystal form for a long time not only when they are dispersed in a solvent but also after application of the dispersion. CONSTITUTION:New crystals of dichloro-tin phthalocyanine have intense diffraction peaks at Bragg angles of 8.5 deg., 11.2 deg., 14.5 deg. and 27.2 deg. in the X-ray diffraction spectrum and can be produced by mechanically grinding a known dichlorophthalocyanine with an inorganic salt or by treating with a solvent after the grinding. the objective electrophotographic photoreceptor is made by covering a conductive support with a photoreceptor layer containing the above- mentioned crystals and a binder resin. As the binder resin, a polyvinyl acetal resin, a vinyl chloride/vinyl acetate copolymer, a phenoxy resin or a modified ether-polyester resin is preferably used. The objective coating fluid consists of the above-mentioned crystals, a binder resin and an acetic ester solvent.

Gum compositions containing vinyl laurate/vinyl acetate copolymer

Abstract: Chewing gum and chewing gum bases containing vinyl laurate/vinyl acetate copolymer as a primary elastomer component are provided. The gum compositions also contain certain elastomer plasticizers, softeners, and low melting point waxes. The chewing gum bases provided are substantially free of polyvinyl acetate and glycerol triacetate, and are particularly useful in bubble gum compositions.

Photochromic and fluorescent probe studies in glassy polymer matrices. 5. Effects of physical aging on bisphenol A polycarbonate and poly(vinyl acetate) as sensed by a size distribution of photochromic probes

Abstract: Polycarbonate (PC) was found to possess a local free volume distribution that is more broad than those of polystyrene (PS) and poly(methyl methacrylate) (PMMA). Contrary to aging results in PS and PMMA, physical aging of PC affected theisomerization abilities of the smaller probes as well as the larger probes, and all probes are affected nearly equally. Physical aging an dry and wet poly(vinyl acetate) (PVAc) showed that absorbed water increases the fraction of local free volume sampled by azobenzene as would be expected in a plasticized system.

Sister-chromatid exchanges induced by vinyl esters and respective carboxylic acids in cultured human lymphocytes

Abstract: Vinyl acetate — an efficient inducer of sister-chromatid exhanges (SCEs) — is known to be hydrolyzed in mammalian cells into acetic acid and acetaldehyde, the latter being the likely metabolite responsible for the SCE induction. As similar hydrolysis to acetaldehyde and to a carboxylic acid is also expected for other vinyl esters, five such compounds — vinyl formate, vinyl chloroformate, vinyl propionate, vinyl crotonate and vinyl-2-ethylhexanoate — and five carboxylic acids — formic acid, acetic acid, propionic acid, crotonic acid and 2-ethylhexanoic acid — were tested for their ability to induce SCEs in cultured (72 h) human lymphocytes with a 48-h treatment, starting at 24 h after culture initiation. Vinyl formate, vinyl propionate and vinyl crotonate induced a clear dose-dependent increase in the number of SCEs/cell at concentrations of 0.125–0.5 mM and vinyl chloroformate at 0.063–1 mM, i.e., at roughly the same concentration range as vinyl acetate and acetaldehyde. Vinyl-2-ethylhexanoate required slightly higher concentrations (0.25–4 mM) for SCE induction. All of the carboxylic acids tested also elevated SCEs, but only slightly. Formic acid and crotonic acid produced some SCE increase at a concentration of 10 mM, acetic acid at 5 and 10 mM and propionic acid at 2.5 mM. 2-Ethylhexanoic acid induced SCEs at a lower concentration range (0.63–2.5 mM) than the other acids. The positive concentrations of the first three carboxylic acids lowered the pH of the culture medium immediately after the treatment by 0.5–1.0 pH unit (lowest observed pH 6.53). The pH differences from the control cultures became smaller in measurements done 24 h and 48 h after the beginning of treatment. Propionic acid and 2-ethylhexanoic acid affected medium pH only slightly (maximum drop 0.2 pH units) at the concentrations that induced SCEs. The results lend support to the idea that the efficient SCE induction observed with the vinyl esters results from the formation of acetaldehyde, with carboxylic acids — with the possible exception of 2-ethylhexanoic acid—playing no significant role. The slight SCE induction obtained with the carboxyle acids cannot be explined by lowered pH alone.

Synthesis, polymerization, copolymerization, and transition‐metal coordination of 4‐(2,2′:6′,2″‐terpyridin‐4′‐yl)styrene and its polymers and copolymers

Abstract: Homopolymer 5 from 4-(2,2′:6′,2″-terpyridin-4′-yl)styrene (4) and copolymers 6–8 from 4 and styrene, vinyl acetate, or acrylic acid were prepared by radical-initiated polymerization with 2,2′-azoisobutyronitrile. These polymers containing pendent 2,2′:6′,2″-terpyridinyl ligands readily formed monotridentate complexes with FeCl2, NiCl2, and CuCl2. By reaction of copolymer 6 with 4′-(p-tolyl)-2,2′:6′,2″-terpyridyliron(III) trichloride or 4′-(p-tolyl-2,2′:6′,2″-terpyridylruthenium(III)) trichloride in the presence of ammonium hexafluorophosphate yielded polymer-metal complexes 11a, 11b containing the corresponding bistridentate complexes. A cyclic voltammogram of 11a containing a bis(2,2′:6′,2″-terpyridyl)iron(II) complex showed characteristic Fe2+/Fe3+ redox couples at + 1,12 V vs. saturated calomel electrode, which was also observed as a reversible color change between purple and colorless.

Vinyl acetate modified suspension polymer beads, adhesives made therefrom, and a method of making

Abstract: The present invention relates to a method of suspension polymerization of a pressure-sensitive acrylate copolymer bead having a glass transition temperature of 0° C. or less which are storage stable in addition to being extrudable at temperature below about 340° F. (171° C.). The method comprises making a monomer-containing premix comprising (i) about 70 to about 98 parts by weight of an acrylic acid ester monomer of non-tertiary alcohol, the alcohol having from 1 to 14 carbon atoms, with the average number of carbon atoms being about 4 to about 12, (ii) about 1 to about 10 parts of a polar monomer copolymerizable with the acrylic acid ester, and (iii) about 1 to about 40 parts vinyl acetate monomer, wherein (i), (ii), and (iii) comprise 100 parts of the monomer-containing premix, (iv) about 0.01 to about 0 5 part by weight chain transfer agent, and (v) about 0.05 to about 1.0 part by weight free-radical initiator, wherein (iv) and (v) are each independently based upon 100 parts by weight total monomer content and wherein about 0.05 to about 30 parts by weight modifier moiety based upon 100 parts by weight total monomer content is present in one or more of the following: said monomer-containing premix, said water phase; the oil-in-water suspension; the aqueous suspension of polymer beads after the exotherm of the polymerization has been reached. The monomer-containing premix is then combined with a water phase containing a sufficient amount of suspending agent to form a suspension. The suspension is concurrently agitated and polymerization of the monomer is permitted until polymer beads are formed. The polymer beads are then collected. The invention also relates to the polymer beads themselves and adhesives prepared therefrom.

Electronic absorption and fluorescence spectra of xanthene dyes in polymers

Abstract: The electronic absorption and fluorescence spectra of fluorescein, fluorescein disodium, erythrosine B and rose bengal in different polymers (poly(vinyl alcohol), poly(vinyl acetate) and polyethylene glycol 600) were studied. It has been noted that fluorescein displays very complex dissociation and ionization equilibria in polymers, depending on the polymer—dye interactions. Its fluorescence emission may be assigned to the neutral zwitterion form in aprotic polymers and solvents. The photophysical properties of fluorescein disodium, erythrosine B and rose bengal are strongly dependent on the polymer—dye interactions and on the internal heavy atom effect. These results are very similar to those obtained for liquid solvents.

Thermodynamic study of poly(4-hydroxystyrene)/poly(vinyl acetate) blends by inverse gas chromatography

Abstract: The poly(4-hydroxystyrene) (P4HS)-poly(vinyl acetate) (PVA) system was studied at 170 o C by inverse gas chromatography. Specific retention volumes of several probes in the homopolymers and four blends (0.26, 0.38, 0.51, and 0.76 P4HS volume fractions) were used to measure the thermodynamic interaction between the polymers. The polymer-polymer interaction parameter χ 23 calculated from the Scott-Flory-Hugging formalism showed an apparent dependence on the probes. A method based on the equation-of-state theory was applied to eliminate the influence of the probe on χ 23 . Negative values of the polymer-polymer interaction parameter confirm the miscibility of the system