Water-resistant modified polyvinyl alcohol coating liquid and preparation method thereof, and coating formed by coating liquid

Abstract

The invention discloses water-resistant modified polyvinyl alcohol coating liquid and a preparation method thereof, and a coating formed by the coating liquid. The water-resistant modified polyvinyl alcohol coating liquid comprises the following components in part by mass: 5 to 20 parts of polyvinyl alcohol, 45 to 95 parts of water, 0.1 to 3 parts of nano inorganic substance, 0.8 to 6 parts of modifier, 0.2 to 3 parts of catalyst, 0.05 to 1 part of coupling agent, 1 to 10 parts of regulating agent, 0.05 to 5 parts of adhesion accelerator, 0 to 0.5 part of leveling agent and 0 to 2 parts of wetting agent. The preparation method comprises the following steps of: adding the polyvinyl alcohol into water; heating and stirring; preserving the heat when the temperature is between 90 and 95 DEG C to ensure that the polyvinyl alcohol is dissolved completely; cooling to normal temperature; adding the nano inorganic substance, the catalyst and the modifier and completely stirring; and adding the coupling agent, the regulating agent, the adhesion accelerator, the leveling agent and the wetting agent during use and stirring uniformly. The coating formed by the water-resistant modified polyvinyl alcohol coating liquid prepared by the method has excellent properties.

Description

technical field [0001] The invention relates to a water-resistant modified polyvinyl alcohol coating liquid, its preparation method and the formed coating. Background technique [0002] In recent years, with the continuous development of the food industry, the performance requirements for packaging materials have gradually increased, such as barrier properties to oxygen, carbon dioxide, and moisture. [0003] The earliest developed high-barrier flexible packaging material is polyvinylidene chloride (PVDC), which is mainly used in the packaging of high-end food, medicine, cigarettes and other products. However, PVDC molecules contain a large number of chlorine atoms, which will produce a large amount of dioxin gas to pollute the environment when incinerated, and PVDC is difficult to degrade naturally. [0004] Ethylene-vinyl alcohol copolymer (EVOH) is one of the substitutes of PVDC. EVOH is a modified variety of PVA. However, EVOH is relatively expensive and is a polar poly...

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Problems solved by technology

However, PVDC molecules contain a large number of chlorine atoms, which will produce a large amount of dioxin gas to pollute the environment when incinerated, and PVDC is difficult to degrade naturally

[0004] Ethylene-vinyl alcohol copolymer (EVOH) is one of the substitutes of PVDC. EVOH is a modified variety of PVA. However, EVOH is relatively expensive and is a polar polymer. It cannot be directly compounded with general-purpose materials. It must be used in the production process. Adhesive resin and expensive multi-layer co-extrusion equipment are very expensive, and the barrier properties of this material are greatly affected by humidity, so five-layer co-extrusion equipment must be used to improve its barrier properties

[0005] Polyvinyl alcohol (PVA) is a polyhydroxy polymer with the molecular formula (C 2 h 4 O) n , strong water absorption, soluble in water, due to its intermolecular hydrogen bond, high density, excellent gas barrier performance, but its melting point is as high as 220-240 ° C, and the decomposition temperature is low, etherification begins at 160 ° C, and etherification begins at 200 ° C Begins to break down, making it difficult to thermoplastically process

At present, most of the commercially available PVA films are produced by tape casting, but a series of shortcomings of tape casting limit the popularization and application of PVA films.

[0006] When the traditional water-based modified polyvinyl alcohol coating solution is used, although the coating performance can meet the general packaging requirements, because the polyvinyl alcohol molecule contains a large number of strongly hydrophilic hydroxyl groups, it can form hydrogen bonds with water in a wet state , and associate with water in the form of hydrogen bonds, and the properties of PVA products associated with water will undergo qualitative changes, making it impossible to achieve dense cross-linking in water-based systems, and the adhesion to the substrate is not high

[0007] In the prior art, due to the excessive addition of functional additives in the modified PVA material used, the stability of the coating solution is reduced, and the coating will shrink on the surface of the base film, and the coating uniformity is not enough and The coating is easy to fall off, etc., and the storage period of the coating solution is short

[0008] Chinese patent application 200410034455.1 discloses a modified polyvinyl alcohol coating solution and its production process, by adding additives such as nano-silica, coupling agent, tackifier, plasticizer, etc., to make the polyvinyl alcohol coating layer The water vapor transmission rate and oxygen transmission rate have been significantly improved, but the water resistance, leveling, adhesion and coating uniformity of the coating are poor

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