CS217133B1 - Fixing quick-drying adhesives with reduced cohesion - Google Patents

Abstract

The invention relates to fast-drying fixing adhesives with reduced cohesion, particularly suitable for fixing material stacked in plastic film packaging. The adhesives consist of 0.2 to 20% by weight of polyvinyl acetals or specified acrylic copolymers, 30 to 90% by weight of organic solvents and optionally up to 5% by weight of plasticizers and up to 65% by weight of cohesion-reducing substances from the group including rosin, optionally modified, phenol-formaldehyde novolaks and dian-type epoxy resins with a molecular weight of 400 to 1000.

Description

The invention relates to an anti-slip adhesive with reduced cohesion, particularly useful for fixing stacked material in plastic bag packaging during handling and transport.

The introduction of palletization for some types of Euro wines and products has brought not only a number of economic and technical advantages, which result primarily from the more perfect use of storage and transportation spaces and from more convenient and faster handling of materials, but also some new problems, the most serious of which is the sliding of stacked cargo due to tilting or shaking during transportation, both of individual stacked layers and of the entire set of layers on the pallet*. This leads to the disintegration of the entire palletized cargo, damage to packaging and therefore financial losses caused by material losses and the necessary reloading of goods*.

Therefore, palletization has necessitated the use of various fixation devices for the purpose of maximum stabilization of the load, the best known of which are strapping tapes, namely metal, paper, textile, etc., as well as adhesive tapes made of paper or plastic materials and chemical coating preparations with anti-slip properties /Manipulation of materials 1, 1966, pp. 15-18/.

For fixing material packed in thin packaging (e.g. paper, polyethylene,

PVC - bags, etc.) are not suitable for strapping tapes, as they can easily damage the packaging after being pulled. They are also not suitable for flexible materials, which reduce their volume due to vibrations, causing the tapes to loosen and lose their function. Adhesive paper tapes can usually only be used to fix less bulky loads. Tapes made of plastic, often reinforced with reinforcing fibers, are usually provided with a self-adhesive layer, which may be suitable for fixing, but causes difficulties during depalletization. For these reasons, chemical coating preparations are more advantageous, applied in relatively thin layers, which increase friction on the sliding surfaces, or create a glued joint between them. If the joint is created from coatings with a self-adhesive effect, this method of fixation has similar disadvantages as when applying self-adhesive tapes. In addition, permanently adhesive layers on the packaging after depalletization are often a defect. Other p.-preparations mainly increase the coefficient of friction, creating only a fragile joint without adhesive properties, so their effectiveness is relatively low. The best suited so far are means of blind fixation, whose resistance to shear forces arising from mutual displacement of the contact layers is sufficiently high, but to forces in the direction perpendicular to the adhesive layer is significantly lower, either due to reduced adhesion to the substrate or low cohesion of the adhesive. This type of adhesive is the subject of, for example, Czechoslovak Administrative Court No. 173 413. Their certain disadvantage is a somewhat longer drying time due to the presence of water, so that the immediate fixation effect, which is very often required due to the use of automatic packaging lines, usually occurs only with porous packaging, while with packaging made of synthetic films the full effect is achieved only after the evaporation of a larger proportion of water from the adhesive.

The adhesives according to the present invention do not have the above disadvantages. Its subject matter is fixing quick-drying adhesives with reduced cohesion based on solutions of synthetic polymeric substances and optionally additives modifying the properties of the adhesive in organic solvents, suitable especially for fixing material stacked in plastic film packaging. The essence of the invention lies in the fact that these adhesives consist of 0.2 to 20% by weight of polyvinyl acetals derived from aliphatic aldehydes with a number of carbon atoms of 1 to 4, preferably polyvinyl butyral, and/or acrylic copolymers with a T value of up to 80 °C from 30 to 90% by weight of organic solvents from the group including liquid aliphatic saturated hydrocarbons with a number of carbon atoms of 1 to 8, optionally chlorinated, aliphatic monohydric alcohols with a number of carbon atoms of 1 to 3, aliphatic ketones with a number of carbon atoms of 3 to 5, methyl and ethyl esters of saturated monocarboxylic acids with a number of carbon atoms of 1 to 3, dioxane and benzene, optionally substituted with 1 to 2 methyl groups. In addition to these basic components, the adhesives may also contain up to 5% by weight of plasticizers from the group including esters of saturated dicarboxylic acids with with 6 to 10 carbon atoms and phosphoric acid, derived from primary aliphatic saturated alcohols with 4 to 8 carbon atoms or from phenol or its homologues, and glyceryl monooleate _and up to 65% by weight of cohesion reducing substances from the group including rosin, modified rosin, phenol formaldehyde novo217 133 varnishes and palm type epoxy resins with an average molecular weight of 400 to 1000. Acrylic copolymers here are copolymers of alkyl esters of acrylic or methacrylic acid with a number of carbon atoms in the alkyl group of 1 to 8, or copolymers of these esters with acrylic or methacrylic acid or with amides, methylolamides, alkoxymethylamides and nitriles of these acids.

The advantage of the fixing adhesives according to the invention is primarily their high drying speed, which allows stacking of packaged material, especially in bags made of plastic films, immediately after applying the adhesive and without the risk of slipping and disintegration of the stored unit. The adhesives are colorless, transparent, and non-sticky after drying, so they do not optically disrupt the surface of the packaging or their possible decorative finish. They have a high anti-slip effect, but the cohesion of the formed blinds is so low that it allows easy removal of individual parts of the fixed set without damaging the packaging.

The polyvinyl acetate component of fixation adhesives consists of synthetic polymeric substances prepared by acetalization of polyvinyl alcohol with aliphatic aldehydes with a number of carbon atoms of 1 to 4, whereby at least 75% of the hydroxyl groups of polyvinyl alcohol must be converted into the acetate form. This is mainly polyvinyl formal obtained by acetalization of polyvinyl alcohol with formaldehyde or the more accessible and even more suitable polyvinyl butyral derived from butyraldehyde.

For the above application, various wastes of these polymers processed in other industries can also be used quite advantageously, e.g. waste polyvinyl butyral from the production of laminated safety glass.

Instead of the polyvinyl acetal component or even in a mixture with it, acrylic polymers can also be used, the glass transition temperature of which /T _g / does not exceed 80. They are copolymers of various acrylic monomers, either copolymers of only acrylic or methacrylic acid esters with the number of carbon atoms in alkyl groups from 1 to 8, or copolymers of these esters with some other types of acrylic monomers, i.e. with acrylic and methacrylic acid, with their amides, methylamides, alkoxymethylamides and nitriles.

Another necessary component of the adhesives according to the invention are organic solvents that dissolve both the aforementioned polymeric substances and any other components. These include aliphatic saturated hydrocarbons that are liquid at ordinary temperatures with a number of carbon atoms of 4 to 8, represented mainly by low-boiling types of gasoline, chlorinated aliphatic saturated hydrocarbons with a number of carbon atoms of no more than 3, e.g. methylene chloride, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, etc., aliphatic saturated monohydric alcohols with a number of carbon atoms of 1 to 3, i.e. methanol, ethanol and propanol, aliphatic ketones with a number of carbon atoms of 3 to 5, namely acetone, methyl ethyl ketone and diethyl ketone, or also methyl and ethyl esters of saturated monocarboxylic acids with a number of carbon atoms of 1 to 3, especially acetic acid. Dioxane or benzene, or their homologues, i.e. toluene and xylene, are also excellent solvents. Due to the requirement for the fixation adhesive to dry as quickly as possible, it is more advantageous to use solvents with a low boiling point.

If necessary, depending on the mechanical properties of the basic polyvinyl acetal and/or acrylic copolymer, the mentioned fixing adhesives can also be plasticized, by adding up to 5% by weight of plasticizers commonly used for various types of macromolecular substances. Suitable plasticizers are in particular esters of saturated dicarboxylic acids with a number of carbon atoms of 6 to 10 derived from primary saturated aliphatic alcohols and a number of carbon atoms of 4 to 8, especially dibutyl phthalate, diethyl phthalate, dibutyl sebacate, etc., as well as phosphoric acid esters derived from the mentioned alcohols or from phenol or its homologues, e.g., tributyl phosphate, triphenyl phosphate, tricresyl phosphate, etc., and also oleic acid monoester derived from glycerol.

Very suitable additives from the point of view of the application properties of the adhesives according to the invention are some low-molecular and high-molecular substances that reduce the cohesion of the adhesive layer while maintaining or even increasing the shear strength of the bonded joint. Rosin is well suited for this purpose, either unmodified or modified, e.g. by esterification with polyhydric alcohols, namely glycerol and pentaerythritol, or by reaction with phenol- or polyphenol formaldehyde.

Ζϊί ±33 hyd resins. In addition to substances of this type, phenol-formaldehyde novolaks or epoxy resins based on diane with an average molecular weight of 400 to 1000 can also be used. These additives can be added in amounts up to 65% by weight of their content in the adhesive.

The fixing adhesives according to the invention are usually prepared by conventional dissolution of solid components in the organic solvents used and optionally further homogenization of the resulting solutions with liquid plasticizers. This results in adhesives of various viscosities which can be applied either manually, e.g. by brush, spraying, etc., or by means of various application devices, often forming the last stage of packaging/bagging/lines.

The subject matter of the invention is further illustrated by specific examples of adhesive compositions, which, however, do not limit its scope in any way.

Example 1

Rosin 62.5% mass Polyvinyl butyral 0.9 II Dioctyl phthalate 1.8 II Methylene chloride 26.8 II Stanol 8.0 II

Example 2

Rosin 8.9 ? q masses Polyvinyl butyral 0.9 II Dibutyl phthalate 1.8 II Ketylene chloride 80.4 It Ethyl acetate 8.0 II

Example 3

Mixed ester of glycerol and rosin acids rosin / ChS-Abiester 90 / 40.4% mass Polyvinylformula 1.6 II Triphenyl phosphate 3.2 II Ketylene chloride 40.3 II Dioxane 14.5 II

Example 4

Example 5

Epoxy resin based dianu about the molar mass in average rio 47.2% mass Polyvinyl butyral 0.4 II Dibutyl phthalate 1.9 11 Acetone 47.2 II Ethanol 3.3 II Phenolphoraldehyde novolac 30.9% mass Polyvinyl butyral 3.7 11 Glyceryl monooleate 1.2 11 Methylene chloride 30.9 11 M ethanol 33.3 11

217 133

Example 6

Copolymer of 2-ethylhexyl acrylate with butyl methacrylate in wt.

ratio 30 < 12 10.2% mass Rosin 12.0 tt Polyvinylbut wipes 4.0 1» Dioxane 14.8 11 Toluene 57.2 II Dioctyl phthalate 1.8

Example 7

Phenol formaldehyde resin modified with rosin/ChS-Abifen 130/ 8.2 ? 'about matter Polyvinyl butyral 1.6 » Dioctyl phthalate 1.6 tt Acetone 73.8 It Ethanol 14.8 those

Example 8

Diane-based epoxy resin with an average molecular weight of 970 40.3% mass Polyvinylformal 1.8 tt Tributyl phosphate 3.0 tl I.ethylene chloride 40.4 tt Dioxane 14.5 tt

Example 9

2-ethylhexyl acrylate copolymer, butyl methacrylate, N-isobutoxyacrylate- mide and acrylic acid in wt. ratio 30 i 12 i 2 i 0.6 16.4% mass Rosin 41.0 tt Dibutyl sebacate 1.6 tt Gasoline / boiling point 80-110 °C / 41.0 tr THE SUBJECT INVENTED E Z U

Claims (2)

CLAIMS 1. Fastening adhesives with reduced cohesion based on solutions of synthetic polymeric substances and, where appropriate, additives to adjust the adhesive properties, in organic solvents, in particular suitable for fixing material stacked in plastic film packages, characterized in that they consist of 0.2 to 20% hmot.polyvinylacetalů derived from aliphatic ALDE Hydes having a carbon number of 1-4, preferably polyvinyl butyral, and / or acrylic polymers, co on the value T _g and 80 ° C, 30 to 90% by weight, of organic solvents from the group consisting of liquid aliphatic saturated hydrocarbons having 1 to 8 carbon atoms and optionally chlorinated aliphatic monohydric alcohols having 1 to 3 carbon atoms, aliphatic ketones having 3 to 5 carbon atoms, methyl and ethyl esters of saturated aliphatic monocarboxylic acids having 1 to 3 carbon atoms, dioxane and benzene, optionally substituted with 1 to 3 carbon atoms 2 methyl groups, and optionally up to 5% by weight of a plasticizer selected from the group consisting of saturated diacrylic acid esters having a carbon number of 6 to 10 and phosphoric acid derived from primary saturated aliphatic alcohols having a carbon number of 4 to 8 or phenol or its homologues, and glyceryl monooleate, and up to 65% by weight of the cohesion-reducing substances selected from the group consisting of rosin, modified rosin, phenol-formaldehyde novolaks and dian-type epoxy resins having an average molecular weight of 400 to 1000. 2. A fast-drying adhesive according to claim 1, characterized in that it is acrylic The copolymers include copolymers of alkyl esters of acrylic or methacrylic acid having a carbon number in the alkyl group of 1 to 8, or copolymers of these esters with acrylic or methacrylic acid or with amides, methylolamides, alkoxymethylamides and nitriles of these acids.