Cellulose coated copolymers

Fig. 2. A modem film composite of cellulose, coated on one side by vinylidene chloride copolymer and the other, printed, side coated with polyethylene.

Copolymers of diallyl dimethyl ammonium chloride [7398-69-8] with acrylamide have been used in electroconductive coatings (155). Copolymers with acrylamide made in activated aqueous persulfate solution have flocculating activity increasing with molecular weight (156). DADM ammonium chloride can be grafted with cellulose from concentrated aqueous solution catalysis is by ammonium persulfate (157). Diallyl didodecylammonium bromide [96499-24-0] has been used for preparation of polymerized vesicles (158). 

Oil-base (including oil-modified alkyd resin) paint films should not be used in alkaline environments as the paint will deteriorate owing to saponification alkali-resistant coatings are provided by some cellulose ethers, e.g. ethyl cellulose, certain polyurethane, chlorinated rubber, epoxy, p.v.c./ p.v.a. copolymer, or acrylic-resin-based paints. In particular, aluminium and its alloys should be protected by alkali-resistant coatings owing to the detrimental effects of alkali on these metals. 

The stabilizing of aqueous latexes succeeded by using emulsifiers (anionic, nonionic) and/or their mixture, steric stabilizators (polyvinyl alcohol (PVOH), hydroxyethyl cellulose, polyethylene glycol, new protective colloids etc.), and polymerizable surfaces active agents, in general. Vinyl acetate (VAc) emulsion homopolymers and copolymers (latexes) are widely used as binders in water-based interior and exterior architectural paints, coatings, and adhesives, since they have higher mechanical and water resistance properties than the homopolymers of both monomers [2, 4, 7]. 

Plasticizers are used in the polymer industry to improve flexibility, workability, and general handling properties. Dibutyl sebacate and phthalates, such as dibutyl phthalate, diethyl phthalate, dicyclohexyl phthalate, butylbenzyl phthalate, and diphenyl-2-ethylhexyl phosphate, serve widely as plasticizers in vinylidene chloride copolymers, nitrocellulose-coated regenerated cellulose film, and cellulose acetate (Castle et ah, 1988a). In PVC, di(2-ethylhexyl)... 

Nowadays, the sieving matrices most employed in CSE are polymer solutions that under suitable conditions may form a transient mesh or sieving matrix that provide the size-based separation of charged biopolymers. The polymer solutions can be formulated with linear acrylamide and N-substituted acrylamide polymers, cellulose derivatives, polyethylene oxide, and its copolymers or with a variety of polymers, such as polyvinylpyrrolidone (PVP), polyethylene oxide (PEO), and hydroxypropyl cellulose(HPC), which do not necessitate the preventive coating of the capillary wall due to their ability to dynamically coat the inner surface of the capillary, resulting in suppressed EOE and sample interactions with the capillary wall. 

Adhesion of Coatings. Except for K-l polycarbonate [4,4 -(2-nor-bornylidene)diphenol polycarbonate] (4), an experimental polymer (inherent viscosity 0.85), all the coatings were prepared with commercial products EAB-381-0.5 and EAB-381-20 cellulose acetate butyrates from Eastman Chemical Products, Inc. VYHH vinyl chloride (87%)/vinyl acetate (13%) copolymer from Union Carbide Corp. Butvar B76 poly-(vinyl butyral) from Shawinigan Resins Corp. Plexiglas V poly (methyl methacrylate) from Rohm and Haas Co. Dylene P3I polystyrene from... 

Shellac is the oldest known material that has been used as enteric coating material. However, as a natural material, it lacks a crucial quality criterion of more modern polymers (i.e., batch-to-batch reproducibility). Hence, the most commonly used polymers today are the synthetic methacrylate copolymers or semisynthetic derivatives of cellulose. The main structural element of these polymers is an acidic function (either phthalate or methacrylic acid), which is responsible for the pH-dependent dissolution. 

A survey of the German market showed that more than 50% of enteric formulations were coated with methacrylate copolymers, about 40% with cellulose derivatives, 5% with shellac, and 3% with other materials [1], Enteric coating materials (Table 1) are described in various publications [21, 22], In addition to polymers mentioned in Table 1, others are being studied (e.g., to obtain release at lower pH) [23], Polymers with a dissolution at lower pH are intended for the protection of drugs in acidic medium and not for the protection of the gastric mucosa. 

To achieve enteric protection of the core, at least 3-4 mg/cm2 of polymer have to be applied (Figure 4). The precise amount of film coating depends on the type of polymer that is applied. Cellulose derivatives usually require higher amounts of polymer to obtain the same protection as methacrylic acid copolymers. A thin layer of 4 mg/cm2 of methacrylate copolymer will dissolve within approximately 10 minutes. However, if increasing layers of polymer are applied, the dissolution time will be prolonged, which can be used to delay the dissolution of the dmg in the small intestine (Figure 5). 

As previously discussed, food effects are an important parameter for enteric-coated systems, especially for drugs, that are sensitive to food. Pancreatic enzyme-containing products fail when they come in contact too early with lipids, proteins, and carbohydrates present in food. The clinical efficacy of pancreatic enzymes formulated as enteric-coated tablets was investigated in man and dog [44], The enteric materials examined were hydroxypropyl methylcellulose phthal-ate (HPMCP), cellulose acetate phthalate (CAP), and the methacrylic acid copolymer USP/NF Type C. In vivo behavior monitored by x-ray scintigraphy showed clear differences between the three coating formulations. HPMCP-coated products adhered to the gastric mucosa, whereas CAP and methacrylate copolymer... 

Naproxen sodium tablets were used in an in vivo-in vitro evaluation with four different polymeric dispersions, cellulose acetate phthalate (CAP), cellulose acetate trimellitate (CAT), 50 50 CAP/CAT, and methacrylic acid copolymer [64], The study indicated that coating material that dissolves at a more acidic pH in vitro (such as CAT at pH 4.5) will also dissolve at a more acidic pH in vivo (i.e., the coating dissolves higher up in the GI tract). In addition, it was found that aging did not markedly affect dissolution characteristics of CAT or methacrylic acid copolymer-coated tablets. 

A primary use of vinylidene chloride copolymer lacquers is the coating of films made from regenerated cellulose or of board or paper coated with polyamide, polyester, polypropylene, poly(vinyl chloride), and polyethylene. The lacquer imparts resistance to fats, oils, oxygen, and water vapor (165). 

For the packaging of sensitive foods, PP films are coated with polyvinylidene chloride, polyvinyl acetate, EVAcopolymers, polyacrylates, styrene-butadiene copolymers, LDPE, poly-l-butene or random copolymers of propene with ethylene and 1-butene. By using these various coatings PP has recently sharply reduced the use of regenerated cellulose (cellophane), the previous market leader in this area. 

ATBC is used as a plasticizer for flexible films made of vinylchloride-vinylidene chloride copolymer and cellulose. It is used as a plasticizer in food contact applications and in vinyl toys for children (low toxicity). ATBC provides adherence to metals, low volatility, and resistance to yellowing. Also used in ink formulations, vinyl gloves, a non-VOC solvent in nitrocellulose propellants, a plasticizer in nail polishes, adhesives and coatings, and for coating both paperboard and foil. 

Use Imparts water tolerance and vapor permeability to copolymer films latex and water-based coating compositions adhesion improver for cellulosics, concrete, glass cross-linking agent in polyester resins color photography. 

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