CS263924B1 - Weldable paint on the base of acrylic copolymers solutions in organic solutions for heat sealing of cellophane foils - Google Patents

Abstract

The purpose of the solution is to ensure a perfect weldability and high strength cellophane weld packaging foils applicable to high-speed ball automatech. This is achieved by a suitable formulation of a weldable lacquer based on acrylic solutions copolymers in organic solvents with addition of nitriculose, plasticizers and additives from the group comprising: natural and synthetic resins, substances vascular with a softening point of 30 to 90 ° C and inorganic powder fillers.

Description

The present invention relates to a process for the preparation of a weldable lacquer based on acrylic copolymers in organic solvents containing additives for the thermal bonding of cellophane.

Viscose films, referred to as cellophane, play an important role as packaging materials for the food industry and consumer industrial packaging of articles of all kinds. These films are practically air- and gas-tight, they are also characterized by transparency, odor and oil resistance. The mechanical properties of these films are also good. However, their resistance to water vapor penetration is very low and these films swell strongly when in contact with water. However, high air humidity permeability is extremely unsuitable for many applications. For these reasons and in order to ensure the weldability of the cellophane in the packaging machines, these films are treated with a thin layer of transparent lacquer, a maximum of 6 g of lacquer / m ^of film. For the purposes of packaging, the cellophane films are lacquered primarily with the following compositions: nitrocellulose-based solution lacquers, polyvinylidene chloride-based polymer solutions and polyvinylidene chloride-acrylonitrile copolymers.

Since the late 1920s, cellophane-based cellophane coating formulations, especially nitrate, such as pat. USA ě. The composition of this composition is later only practically modified with various additives. A number of patents relate to these modifications, e.g. U.S. Pat. E. 799 631, brit. U.S. Pat. No. 459,344. A number of patents include the formulation of a weather-resistant final product, but a special intermediate layer is required to achieve complete water resistance (e.g., U.S. Patent No. 2,252,091, German Patent No. 748,357 J. newer patents relating to the formulation of nitrocellulose welding lacquers include, for example, item No. 102 223. These lacquers are characterized by relatively good hot weldability, but are not usable for applications on modern high-speed welding machines. polyvinylidene chloride copolymer varnishes (U.S. Pat. No. 639,241, U.S. Pat. No. 2,837,296) In the case of solutions of these copolymers in organic solvents, dissolution of the optimum amount of copolymer in solvents is a major problem (limiting the content of individual monomers in the polymer, aqueous dispersions). in turn, they are not suitable for all applications copolymers of vinylidene chloride with acrylonitrile, eg U.S. Pat. No. 2,618,575, No. 3,817,780. Some coating systems for cellophane film must be anchored with melamine-formaldehyde resins to achieve the desired performance properties.

The present invention is directed to a weldable lacquer for thermally bonding cellophane film based on solution acrylic copolymers in organic solvents containing additives. According to the invention, the lacquer consists of 6 to 25 wt. parts by weight of acrylic copolymers prepared by free-radical copolymerization of a monomer mixture containing 54 to 99.9 wt. % of esters of acrylic and / or methacrylic acid derived from aliphatic primary or secondary monovalent to divalent alcohols having carbon numbers of 1 to 13, 0.1 to 8 wt. α, β-ethylenically unsaturated aliphatic mono- to dicarboxylic acids having a carbon number of 3 to 5, or anhydrides thereof, and optionally up to 1 wt. glycidyl esters of acrylic acid and / or alkyl derivatives thereof having a number of carbon atoms in the alkyl substituent of 1 to 4, 75 to 96 wt. parts of organic solvents, 0.3 to 3.1 wt.%, parts of nitrocellulose having a nitrogen content of 11.7 to 12.3 wt.%, 0.1 to 2.2 wt. % of plasticizer and 0.05 to 1.3 wt. % of additives, in particular from the group consisting of natural and synthetic resins, waxy substances with a softening point of 30 to 90 ° C and inorganic powder fillers.

The varnish according to the invention ensures good weldability and high weld strength of the cellophane wrapping film and allows its use on high-speed packaging machines. Another advantage of this welding varnish is its lightfastness and achievement of the required properties without anchoring the cellophane.

To prepare a sealable film on cellophane films, I use an acrylic copolymer prepared by the free-radical copolymerization of a monomer mixture in which the essential component is esters of acrylic and / or methacrylic acid with aliphatic alcohols of 1 to 16 carbon atoms, such as e.g.

methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentamol, isopentanol, pentanol-3-methylbutanol,

2-methylbutanol, n-hexan-ol,

1-methylpentanol,

2-Methylpentanol

3-Methylpentanol

2-ethylbutanol, n-heptanol,

1-methylhexanol,

2-Methylhexanol

3-methylhexanol, heptanol-3,2-ethylpentanol, n-octanol, iso-octanol,

2-ethylhexanol,

3,5,5-trimethylbexanol, n-decanol or dodecanol.

The other constituents of the basic copolymer are acrylic and / or methacrylic acids, optionally other α, β-ethylenically unsaturated aliphatic acids, such as wool-acetic, crotonic, allylacetic and maleic acids and / or their anhydrides and unsaturated functional acrylic and / or methacrylic compounds, in particular glycidyl and hydroxy esters. For certain purposes, the base copolymer may comprise styrene. Some of the properties of the weldable lacquer according to the invention can be further improved and improved by the addition of organic and / or inorganic substances. An important component of the weldable adhesive of the present invention is nitrocellulose. These are ester-soluble types with a nitrogen content of 11.7 to 12.3% by weight. Another component of the weldable lacquer is organic plasticizers (plasticizers). For this purpose, plasticizers based on mono-, di-, tri- and higher esters of organic acids having 4 to 18 carbon atoms (butyric, caprylic, lauric, palmitic, stearic, hydroxystearic, violet, adipic, etc.) can be advantageously used. aliphatic primary, secondary or cycloaliphatic alcohols having 1 to 12 carbon atoms, mono-, di- and triglycols and their monoesters, polyols and aryl alcohols (such as inethanol, ethanol, n-butanol, isobutanol, n-hexanol,

2-ethylbutanol,

1,3-dimethylbutanol, n-octanol, isooctanol,

2-ethylhexanol, n-decyl alcohol, cyclohexanol, ibenzyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, and the like; organic phosphates such as tri-n-butyl phosphate, tricresyl phosphate, and liquid oligomeric substances having an average molecular weight of 180 to 180 4,000 such as polyethylene glycols, polypropylene glycols, low molecular weight oligomers of acrylic and / or methacrylic esters with aliphatic alcohols ·

Some of the properties of the weldable lacquers of the present invention can be further improved and improved by the addition of organic and / or inorganic additives. The cohesive and adhesive properties are modified by the addition of modified or unmodified natural and / or synthetic resins such as rosin, modified rosin-based resins, copal resins, shellacs and balsams, phenoformaldehyde resins, epoxy, epoxyester, polyester resins, vinyl acetate / maleic acid copolymers or vinyl acetate with ethylene, and the like.

Foil blocking can be reduced by antiblocking agents such as various forms of silica, clay, starches, stearamide, divalent metal stenates, tertiary ammonium salts and silicones. Some properties, especially water vapor permeability, are regulated by waxy substances of natural and synthetic origin. Organic solvents are a further component of these lacquers and are not limited thereto. Preferably, solvents such as acetic acid esters (ethyl acetate, butyl acetate), primary and secondary alcohols (isobutanol), aromatic solvents (toluene, xylene), and the like can be used.

The lacquers according to the invention are suitable for coating cellophane films. The coating of the film is carried out on existing equipment such as the use of nitrocellulose or saran solvent lacquers. In this way, a wrapping film can be prepared to provide weldability at 80 to 180 ° C and at jaw pressure of 0.1 to 0.5 MPa.

Example 1

9.5

88.5

0.94

0.90

0.16 wt. % by weight of an acrylic copolymer prepared from wt. % methyl methacrylate 45 wt. % butyl acrylate 6 wt. 2-ethylhexyl acrylate 2% w / w; acrylic acid wt. a part of the solvent mixture containing 29% 10% / 1% by weight,

500 wt. ethyl acetate wt. toluene wt. butylacetate wt. ethanol of a portion of nitrocellulose having a K-value of wt. % dicyclohexyl phthalate wt. % of the additive mixture consisting of

13.6% wt. amorphous silica ·

50.6% wt. paraffin with a softening point of 62 ° C

9.8 wt. rosin 26.0% wt. vinyl acetate-ethylene copolymer (vinyl acetate content 40% by weight)

The prepared welding varnish is a clear, low-viscosity liquid suitable for application to cellophane in a coating thickness of 1.3 to 6.0 g / m ² .

Example 2 wt. % of the acrylic copolymer prepared according to Example 1 by weight. % by weight of the solvent mixture, containing wt. % butyl acetate 3 wt. % toluene 92 wt. ethyl acetate

1.96 wt. % of nitrocellulose © K-value 1200

1.74 wt. % of dicyclohexyl phthalate

0.30 wt. % of the additive mixture consisting of

46.7% wt. paraffin, softening point ° C

13.3 wt. of amorphous silica

13.3% rosin

26.7% of a mixed glycerin ester of rosin and an adduct of resin acids with maleic anhydride with an acid number of not more than 15 milligrams of KOH / g and a softening point of 125 ° C

1.1 wt. % of the additive mixture consisting of 12 wt. % amorphous silica; % of paraffin having a softening point of 62 ° C; % stearamide 21 wt. of a mixed glycerin ester of rosin and an adduct of resin acids with maleic anhydride having an acid number of max. 15 mg KOH / g and a softening point of 125 ° C by weight rosin

Example 3

..WExample 5

9.5 copolymer,

88.0

1.17

1.04

0.29 wt. % of acrylic prepared from 25 wt. % butylacrylate wt. % butyl methacrylate wt. % methyl methacrylate 2 wt. % lauryl methacrylate. % 2-ethylhexyl acrylate 1.7 wt. % acrylic acid 0.3 wt. glycidyl methacrylate wt. % by weight of the solvent mixture; % ethyl acetate wt. % xylene wt. butylacetate wt. % of K-value nitrocellulose

7.0

91.0 copolymer, wt. parts of acrylic prepared from 46 wt. styrene 42 wt. % butyl acrylate 6 wt. % lauryl methacrylate 4 wt. % butyl methacrylate 2 wt. methacrylic acid wt. part of the solvent mixture of composition

800 wt. % by weight of dicyclooctyl phthalate; % of the additive mixture consisting of 11.4 wt. of amorphous silica

58.0 wt. of paraffin having a softening point of 0.81

0.83

0.34; 62 ° C

17.6% wt. % of a mixed glycerin ester of rosin and an adduct of resin acids with maleic anhydride having an acid number of 13 milligrams of KOH / g and a softening point of 145 ° C by weight. zinc stearate% 35% 10% 5% by weight 500 wt. ethyl acetate wt. xylene wt. butylacetate wt. % of toluene of the nitrocellulose part of the K-value. % by weight of the plasticizer mixture; % dicyclohexylphthalate 10 wt. % dibutyl phthalate wt. tricresyl phosphate mass. % of the additive mixture consisting of 13.6 wt. % amorphous silica; % of paraffin having a softening point of 62 ° C; % copolymer of vinyl acetate with ethylene with an ethylene content of 65 wt.

% wt. talku

9.4 wt. rosin

Example 4

19.4 wt. % by weight of an acrylic copolymer prepared from wt. % butylacrylate wt. % methyl methacrylate wt. % styrene wt. mehacrylic acid 75 wt. % by weight of the solvent mixture; % ethyl acetate 25% wt. % toluene 12 wt. % butyl acetate; ethanol 1 wt. isopropanol

2.5 wt. % by weight of the nitrocellulose mixture consisting of wt. % nitrocellulose having a K-value of 400 wt. nitrocellulose with a K-value of 840

2.0 wt. parts of dicyclohexyl phthalate

Example 6

8.5 wt. % by weight of an acrylic copolymer prepared from 40 wt. % butylacrylate wt. ethyl acrylate

2.5 wt. % 2-ethylhexyl acrylate 49 wt. methyl methacrylate

0.5 wt. methacrylic acid

89.6 wt. % of the solvent mixture of Example 1

0.7 wt. % of nitrocellulose with a K-value of 700

0.65 wt. % of dicyclooctyl phthalate

0.55 wt. % by weight of the additive mixture consisting of wt. % amorphous silica; % of paraffin having a softening point of 62 ° C; % zinc stearate wt. % rosin copolymer of vinyl acetate with ethylene with an ethylene content of 65% by weight;

Claims (1)

Subject Weldable varnish for thermal bonding of cellophane films based on solutions of acrylic copolymers in organic solvents containing additives, characterized in that it consists of: 6 to 25 parts by weight of acrylic copolymers prepared by the free-radical copolymerization of a monomer mixture containing 54 to 99.9% by weight of acrylic and / or methacrylic esters derived from aliphatic primary or secondary monohydric alcohols and carbon numbers from 1 to 16, 0.1 to 8 % by weight of α, β-ethylenically unsaturated aliphatic mono- to dicarboxylic acids having a carbon number of 3 to 5, or anhydrides thereof, and optionally up to 1% by weight OF THE INVENTION glycidyl esters of acrylic and / or methacrylic acid and up to 50% by weight of styrene and / or its alkyl derivatives having a carbon number of 1 to 4 alkyl substituents 75 to 96 parts by weight of organic solvents, 0.3 to 3.1 parts by weight of nitrocellulose with a nitrogen content of 11.7 to 12.3% by weight 0.1 to 2.2 parts by weight of plasticizers; and 0.05 to 2.3 parts by weight of additives, in particular from the group comprising natural and synthetic resins, waxy substances having a softening point of 30 to 90 ° C and inorganic powdered fillers.