FI70042B - FRAMEWORK FOR FRAMEWORK FOR SUSPENSION OEVERDRAG - Google Patents

Abstract

1. A process for the production of self-adhesive coatings by applying acrylates to a base and exposing the coating to high-energy radiation, wherein derivatives of dihydroxypropyl acrylates are employed as the acrylates, these are mixed with (a) from 0 to 120% by weight of polymers having a glass temperature below 0 degrees C and a K value of from 10 to 80, and/or (b) from 0 to 90% by weight of a conventional tackifying resin, and the mixture is applied to the base, the amount of (a) and (b) together being not less than 5% by weight and the percentages of (a) and (b) being based on the weight of the dihydroxypropyl acrylates derivatives.

Description

70042

The present invention relates to a method for producing self-adhesive coatings by applying a pourable mass containing polymerizable unsaturated olefinic compounds to the surfaces of substrates 5 and irradiating the applied layer with high-energy radiation.

Contact adhesives are increasingly used in the manufacture of labels, adhesive tapes, decorative films and similar self-adhesive thin pieces.

The contact adhesive masses used for this purpose must have certain properties: Not only must the adhesion of the coating to the surfaces be good, the cohesion of the coating must be as high as possible. The contact adhesive must be able to withstand the effects of light, air and moisture well, and the adhesion must remain constant over the widest possible temperature range, i.e. adhesion to surfaces must be good even at low temperatures, and cohesion must not decrease substantially at high temperatures.

It is very common in contact sizing to use rubber solutions as contact sizing compounds. Self-adhesive elastomers become contact adhesives when 25 curing resins are added. Rubber-based compounds have good adhesion to surfaces (sticky) and high cohesion (toughness). However, in terms of their aging time, it is desirable: the adhesive films made using them turn yellow rapidly, and their adhesive capacity 30 decreases. Another disadvantage of rubber adhesives is that they have to be applied to the substrate materials dissolved in organic solvents and dried. In practice, large amounts of solvent vapors are generated, but their expensive recovery is unavoidable for health, environmental reasons and economic reasons.

Contact adhesives containing acrylate polymer have better aging resistance. However, these contact adhesives are also applied to the substrate materials 5, most often in the form of organic solutions or dispersions, and thus also have the disadvantage of drying or solvent recovery. An important prerequisite for the applicability of acrylate polymers in contact adhesives is a relatively high molecular weight because only in this way good cohesion values are achieved. But in the case of contact adhesives, the high molecular weight of the polymer means the high viscosity of the solution, so in practice only solutions with a low concentration can be prepared and used. As a result, large amounts of solvent must be transported, used and handled as safely as possible. To overcome these difficulties, low molecular weight, low viscosity acrylate polymer solutions were developed which are crosslinked after application to the substrate-20 material. In this case, two systems can be distinguished, namely a two-component system and a self-bridging one-component system. In the case of a two-component system, the two reacting components, for example a solution of a polymer containing hydroxyl groups and a solution of a polyvalent isocyanate, are mixed together just before application, and the mixture is then applied to a substrate. One disadvantage of this method is that both components remain mixed only to a limited extent and coagulate rapidly. Prolonged stoppage of the coating machine can thus lead to laborious cleaning and repair work. A self-crosslinking one-component system that already includes both reactive components generally has the disadvantage of a susceptible storage life. To ensure adequate storage stability, the reactivity must be kept low at 3,70042 to prevent contact adhesive solutions from coagulating prior to application. This inevitably results in a relatively low rate of crosslinking reaction with the substrate material, so that such a sys-5 system reacts too slowly in the case of a fast coating machine, failing to achieve the molecular weights required for the highest cohesion values.

Another possibility is to apply the contact adhesive masses to the substrate films in the form of melts at a temperature above 100 ° C. However, it is inconvenient from a practical point of view here that in most cases melts with a very high viscosity have to be treated at high temperatures. In addition, the disadvantage of these contact adhesives is that, due to the high processing temperatures, heat-sensitive substrate materials can only be coated using special measures, or they cannot be coated at all. In addition, the contact adhesive layer formed from the melt has insufficient heat resistance as well as the durability of the soft meters.

In contrast, NL-A-6 606 711 already discloses tapes which are prepared by coating a substrate with a polyacrylate adhesive in which at least one monomeric acrylate, for example ethylhexyl 25 acrylate, or a mixture thereof and a copolymerizable monomer or a prepolymer-monomer-blend polymer after heating. However, the disadvantages of this process are the equipment costs caused by the additional heating equipment, the limited usability for higher temperature resistant vessels, and the necessity of polymerization accelerators and / or polymerization catalysts. It is also difficult to achieve uniform sizing values using polymerization initiators.

4,70042

In addition, NL-A-7 009 629 describes a process for preparing adhesives in which mixtures containing (meth) acrylic acid esters, such as 2-ethylhexyl acrylate, and organic polymers, such as cellulose derivatives, optionally polyolefins and polyesters, as viscosity regulators, with an agent such as polyvinyl methyl ether is applied as a thin layer to the substrate and treated with run-10 energy radiation; however, a disadvantage of this method is that the cohesion of the adhesive layers thus obtained is not sufficient for many applications in the field of contact adhesives.

U.S. Patent No. 3,772,063 discloses adhesive tapes in which an adhesive layer is obtained by irradiating a mass containing at least one (meth) acrylic acid ester having an alkyl radical of 1 to 9 carbon atoms with ionizing radiation. In this case, however, only adhesive layers with a relatively low cohesion are obtained.

Adhesive tapes or adhesive films prepared by irradiation with high-energy radiation and having a high shear strength are known from DE-A-24 55 133, but in this case 25 C spread as a melt.

Finally, DE-A-23 57 486 discloses a process for preparing self-adhesive coatings, which process is characterized in that a room-temperature fluid mixture containing (A) at least one polymerizable compound containing one carbon-carbon double bond which forms polymers capped at room temperature, (B) at least one compound containing at least two double bonds, and (C) a polymeric substance having a softening point of less than 50 ° C and an average molecular weight of 500 to 10,000 are treated with ionizing radiation . In this case, acrylic and methacrylic acid esters of alkanols having from 4 to 12 carbon atoms can in most cases be used as monomers (A). The adhesive layers prepared according to this method have high shear strength at room temperature and good adhesion to surfaces. The disadvantage, however, is that such air layers have a relatively high cold flow and insufficient shear strength at higher temperatures.

The object of the present invention is to provide a method for producing contact adhesive layers which lack the above-mentioned shells of known methods and which can be easily applied at room temperature and which, after crosslinking with high energy radiation, have high shear strength even at high temperatures and good adhesion to surfaces and plasticizers. The duration of the ability.

It has now been found that self-adhesive coatings can be advantageously prepared by coating substrate materials with acrylic acid esters and irradiating the coatings with high energy radiation when using derivatives of dihydroxypropyl acrylic acid esters as acrylic acid esters and also applying them to polymers having a glass transition temperature below 0 ° C and a K value of 20 to 80 and / or b) 0 to 90% by weight of a conventional tackifying resin and having a total of (a) and (b) of at least 5 wt%; The weight percentages of (a) and (b) are calculated from the weight of the dihydroxypropyl acrylate derivatives. As used herein, the term "dihydroxypropyl acrylic acid ester" 35 refers to both 2,3-dihydroxypropyl-1- and 1,3-dihydroxypropyl-2 compounds. Suitable derivatives of dihydroxypropyl acrylic acid esters are, in particular, their alkyl ethers and esters with saturated carboxylic acids, of which the monoalkyl ethers and monoalkyl carboxylic acid esters of dihydroxypropyl acrylic acid esters are particularly important. Particularly due to their easy availability, the preferred dihydroxypropyl acrylate derivatives have general formulas

10 R - O - CH- - CH - CH- - O - C - CH = CH

£% L · n ^

OH O

and R - O - CH - CH - O - C - CH = CH-

“I II

15 CH2OH O

wherein R is an alkyl or acyl group having 4 to 16 carbon atoms, especially 4 to 12 carbon atoms. Examples of said compounds are the mono- n-butyl, mono-2-ethylhexyl, monoisononyl, monoisooctyl, monodecyl and monolauryl ether of 2,3-dihydroxypropyl acrylate and 1,3-dihydroxyisopropyl acrylate, as well as their monoisovaleric acid ester. , raono-2-ethylhexanoic acid ester, monoversatin acid ester, monolauric acid ester and monopalmitic acid ester.

Such dihydroxypropyl acrylate derivatives can also be used as mixtures. They are easy to prepare by conventional and known methods. The corresponding monoesters can be prepared, for example, by reacting glycidyl acrylate with saturated aliphatic monocarboxylic acids having 4 to 16 carbon atoms or by giving the formula R-O-CH - CH-CH-2/2

35 O

7 70042 wherein R is as defined above, reacting the glycidyl esters or ethers according to acrylic acid, in particular in the presence of catalysts such as tertiary amines or thioethers, at 100-530 ° C; in this case, the second component, usually the glycidyl compound, is placed in a mixing vessel and the second component used in each case is added. Conventional polymerization inhibitors can be used to prevent premature polymerization of the acrylic double bond. Although such methods of preparation are not novel but a general part of the art, the choice of suitable catalysts or catalyst mixtures, reaction temperatures and polymerization inhibitors may affect the properties of the contact adhesive compositions thus prepared, e.g. adhesion properties of the polymerized contact adhesive film. In order to achieve the properties mentioned in the examples of the reaction products or their formulations, the following reaction conditions have proved to be good: 1. Reaction temperatures during preparation:

Monoalkyl ethers of glycidyl acrylate 105-5 ° C 25 Monoalkyl esters of glycidyl acrylate 125-5 ° C

2. Catalysts in the preparation of:

Monoalkyl ethers 1-2 wt% thiodiglycol Monoalkyl esters 0.5-1 wt% thiodiglycol 30 or 0.5 wt% thiodiglycol + 0.2 wt% benzyldimethylamine 3. Polymerization inhibitors:

Generally 300 to 1,000 ppm tris (N-cyclohexyldiazenedium) aluminum 35 + 500 to 1,000 ppm 2,6-di-t-butyl-p-cresol and / or 500 to 1,000 ppm phenothiazine 8,70042

The preparation usually takes place without solvent and without further purification steps, i. monoalkyl ethers and esters of dihydroxypropyl acrylate can be used for further purification to make pulps.

Suitable polymers (a) are polymers which have a glass transition temperature of less than 0 ° C and a κ value of 20 to 80, determined in accordance with DIN 53 726, and which are generally capable of forming a homogeneous solution at room temperature which can be poured at room temperature without dihydroxypropyl acrylate derivatives. Such polymers can be prepared in a manner conventional per se by polymerization using radical initiators by the emulsion, suspension, melt or, preferably, solution method. Suitable polymers or blended polymers are, for example, those containing unsaturated monoolefinic carboxylic acid esters, such as straight-chain or branched acrylic and methacrylic acid esters having 1 to 12 carbon atoms in their alkyl groups, such as methyl, , Butyl, pentyl, hexyl, 2-ethylhexyl, octyl, decyl and dodecyl acrylate and methacrylate, as well as vinyl esters such as vinyl acetate, vinyl propionate, vinyl ethyl hexanoate, vinyl versurate and vinyl versatate. In addition to carboxylic acid esters, other unsaturated olefinic monomers can also be polymerized, such as mono- and dicarboxylic acids having 3 to 5 carbon atoms, for example acrylic acid, methacrylic acid, maleic acid, fumaric acid, diacarboxylic acid or crotonic acid, as well as crotonic acid. Further suitable comonomers include hydroxyl-containing monomers such as hydroxyethyl, hydroxypropyl and hydroxybutyl acrylate and methacrylate, as well as hydroxyl polyoxyacrylates derived from ethylene and propylene oxide oligomers and polymers such as hydroxyl polyoxyacrylates and polymers, and 2,3-dihydroxypropyl acrylate and methacrylate, chlorohydroxypropyl acrylate, as well as vinyl aromatic monomers such as styrene, vinyl toluene, additional (β-unsaturated mono- and / or dicarboxylic acid amides such as (meth) acrylamides such as (meth) acrylamide and methacrylonitrile, vinyl halides such as vinyl chloride and vinylidene chloride, 1,3-dienes such as butadiene and isoprene, and o (-) alkyl esters of unsaturated monoolefinic dicarboxylic acids such as diethyl and dibutyl ester of malonic acid. the contact adhesive compositions used according to the invention may contain polymers (a) up to 120% by weight, preferably 20 to 100% by weight, based on the weight of the dihydroxypropyl acrylate derivatives.

Particularly preferred polymers (a) are copolymers containing acrylic acid esters, vinyl esters or ethers, vinyl aromatic compounds and optionally β-unsaturated mono- dicarboxylic acids.

The compositions used according to the invention may also contain, instead of the polymers (a) or their customary tackifying resins (b) (adhesives), up to 25% by weight, preferably from 5 to 50% by weight, based on the weight of the dihydroxypropyl acrylate derivatives. Suitable resins (b) are, for example, terpene resins, balsamic resins # rosin resins, rosin, hydrogenated rosin, esters of rosin or hydrogenated rosin, such as glycol roliester, pentaerythritol ester, propylene glycol ester, diethylene glycol ester, diethylene glycol ester, Esters of hydroabietyl alcohol formed by complete hydrogenation of rosin, for example benzoic acid or phthalic acid ester, are also suitable.

35 In addition, good tackifiable resins (b) include conventional terphenophenol resins, alkylphenol resins, ketone resins such as condensation products of cyclohexanone, aldehyde resins, carbonyl indole copolymers obtained with, for example, polymerization of styrene, , as well as low molecular weight polyvinyl isobutyl ethers or polyolefins such as low molecular weight polyisobutylene. The total amount of polymers (a) and / or tackifying resins (b) in the contact coating compositions must be at least 5% by weight, based on the weight of the dihydroxy-10 cypropyl acrylate derivatives.

Suitable monomers (c) containing at least two carbon-carbon double bonds are, for example, acrylic and methacrylic esters of polyhydric aliphatic alcohols (preferably having 2 to 12 carbon atoms), such as butane-1,4-diol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, hexanediol diacrylate, trimethylolpropane triacrylate, pentapropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate derivative, such as their acacrylic acid esters, N-alkyl - (N-methylolacrylamide) glycol ether, xylene / bis-acrylamide and bis- (N-methylolacrylamide) diethylene glycol ether. In certain applications, their amount is preferably 2 to 10% by weight, based on the amount of dihydroxypropyl acrylate derivatives.

In the process according to the invention, it is also possible for the mixture to contain other unsaturated monoolefinic monomers (d), such as, for example, acrylic acid esters, preferably butyl, 2-ethylhexyl, nonyl, dodecyl, octyl, isooctyl. - and ethyl diglycol acrylate, as well as vinyl esters, preferably vinyl 2-ethylhexanoate, N-vinyl-35 caprolactam and N-vinylpyrrolidone. The amount of these additional unsaturated monoolefinic monomer 70042 (d) is generally 0-15% by weight based on the weight of the dihydroxypropyl acrylate.

Finally, it is possible to add to the mixtures used according to the invention small amounts of other additives (e) which are customary in contact adhesives, for example plasticizers such as di-butyl, dibenzyl and dioctyl phthalate, stabilizers, fixing agents or also, for example, to control viscosity. , small amounts of solvent.

The polymers (a) and / or tackifying resins (b) are optionally dried and mixed with dihydroxypropyl acrylate derivatives at a temperature below 150 ° C. The mixture can then optionally be mixed with the other monomers (c) and / or (d). It is also possible to get rid of polymer solutions or aqueous or non-aqueous dispersions and to remove the solvent and / or dispersing phase from the mixtures.

Contact adhesive compositions have an almost unlimited "use-20 time" after treatment with high energy radiation, i.e. their viscosity remains unchanged for a long time, and clotting does not occur spontaneously at elevated temperatures.

According to the invention, the contact adhesive compositions are used for the production of self-adhesive coatings by coating thin pieces, and are particularly suitable for the production of adhesive tapes, adhesive films and self-adhesive labels, self-adhesive wall and floor coverings as well as self-adhesive sound insulation materials. Suitable substrate materials are, for example, films made of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride or metals, fibrous materials such as paper, cardboard or textile materials, bituminous materials, glass or wood.

The coating of the substrate materials with the contact adhesive mixtures can take place directly by application, for example by sweeping with a blade, pouring, using rollers or rollers or by means of nozzles. Indirectly when applied, i.e. by the transfer method, the contact adhesive composition can be first applied to a non-stick substrate, for example silicone-treated paper, crosslinked and then transferred to a desired substrate material, for example a film made of soft PVC.

In general, the thickness of the contact adhesive layer 10 is chosen to be more than 5 μm, preferably 20 to 200 μm, which / '2 layer thicknesses correspond to coating amounts of more than 5 g / m 2 and 20 to 200 g / m 2.

To produce a self-adhesive coating, the compositions are applied to the substrate materials by conventional coating equipment, and are preferably irradiated under anaerobic conditions, generally for a short time, with high-energy radiation, especially a high-energy cathode ray.

Suitable radiation sources include, for example, cathode ray generators, both scanning devices and electron envelope devices.

The scanning devices send a cathode beam parallel to the inlet to the adhesive masses. Generally, the beam is directed to the respective working width at a frequency of 100-200 Hz.

Electronic curtain devices do not have a scanner and therefore no oscillating single beam. The electrons come out as a continuous beam over the entire width.

30 When treated with high-energy radiation, the syrupy contact adhesive mixture is transformed into a valuable adhesive film with excellent adhesive properties. The energy dose is most often 1 to 500 kGy (0.1 to 50 megarads). A particularly preferred dose is 30 to 150 kGy (3-15 megarads). The dose depends on the acceleration voltage of the generator, which is generally 150 to 300 kV, preferably 150 to 200 kV, the duration of the radiation, i.e. the rate at which the mixture according to the invention is passed through the generator, and the operating current. By changing the dose, the achievable sizing properties can be changed.

5 In order to evaluate the gluing properties of thin bodies prepared according to the new method, in the following examples, polyester films are coated with contact adhesive mixtures so that the coating thickness 2 is 25 μm (corresponding to a coating amount of 25 g / m 2). The coating applied to the vessel 10 is irradiated with cathode rays using an electron envelope device. A 2 cm wide test strip is used for each coated and irradiated film. To determine cohesion, a shear test is performed and to determine adhesion, a release test is performed as follows:

In the release test, the test strips are glued to the chrome-plated plate and removed in the direction of the adhesive layer, i.e. At an angle of 180 ° and the force required to do so is measured. The drawing speed is 300 mm / min and the measurement is made 24 hours 20 after gluing.

To measure the cohesion of the adhesive layer, a shear test is performed by pressing the test strips onto a high-gloss chrome-plated plate over an area of 2.0 x 2.5 cm. The board is fixed vertically and a load of 1,000 g is applied to the end of the adhesive tape 25. The time by which the gluing is released when a constant tension of 1000 g is applied is then determined. The measurement is performed at 20 ° C and 50 ° C.

The proportions given in the following examples and 30% are by weight unless otherwise indicated.

K values are determined in accordance with DIN 53 726. Abbreviations A or K mean adhesion or cohesion fracture. The softening points indicated in the examples are determined in accordance with DIN 53 180.

14 70042

The glass transition temperature is measured in a conventional manner by means of differential scanning calorimetry.

Example 1 90 parts of a versatic acid monoester mixture of 2,3-dihydroxypropyl 1-acrylate and 1,3-dihydroxypropyl 2-acrylate and 10 parts of a conventional commercial cyclohexanone resin prepared in Ullmanns Encyclopädie der Terhnischen Chemie, Part 10 12, 1976 according to the instructions on page 551 and having a softening point of 80 ° C were mixed together.

After the polyester film was coated with a coating amount of 25 g / m 2 and irradiated with a cathode ray dose of 75 kGy, the following sizing values were obtained: Peel strength: 4.5 N / 2 cm; shear strength below 20 ° C: more than 3 days; shear strength at 50 ° C: more than 3 days.

Example 2

A mixture of 50 parts of a mono-2-ethylhexyl ether mixture of dihydroxypropyl acrylate, 40 parts of a blend polymer prepared from 60 parts of ethyl hexyl acrylate, 38 parts of vinyl acetate and 2 parts of acrylic acid was prepared in a blender at 100 ° C. -25 and having a K value of 60 and a glass transition temperature of -30 ° C, and 10 parts of a conventional commercial rosin glycerol ester having a softening point of 85 ° C.

After the polyester film is coated with a coating amount of 25 g / m 2 and irradiated with a cathode-30 beam dose of 35 kGy, the following sizing values are obtained: Peel strength: 2 N / 2 cm; shear strength at 20 ° C: more than 3 days; shear strength at 50 ° C: 4 hours.

Examples 3-7

50 parts of the versatin acid ester used in Example 1 and 80 parts of the 50% solution of the mixed polymer of Example 2 having a K value of 60 70042 were mixed together and the solvent was evaporated off under reduced pressure.

After the addition of 10 parts of the aldehyde resin prepared according to Example 1 of DE-A-27 57 220, the polyester film was coated with that mass and irradiated with various doses of cathode rays.

Bonding values: 10

Pre-Dose Peel strength Shear strength at western temperature mark (kGy) _ (N / 2 cm) _20 C_50 C_ 3 11 9.6 (A) 40 h (K) 2 h 40 '(K) 15 4 21 9.1 (A) 63 h (K) 5 h (X) 5 42 8.0 (A)> 3 days> 3 days 6 149 7.5 (A)> 3 days> 3 days 7 298 5.9 (A)> 3 days> 3 day 20

Example 8

To the mixture of Examples 3-7 was added an additional 7 parts of trimethylolpropane triacrylate. After coating the polyester film and irradiating with a cathode ray dose of 21 to 25 kGy, the following sizing values were obtained:

Peel strength: 7.4 N / 2 cm; shear strength at 20 ° C: more than 3 days; shear strength at 50 ° C: more than 3 days.

Example 9 70 parts of a mono-n-butyl ether mixture of dihydroxypropyl acrylate, 20 parts of poly-n-butyl acrylate having a K value of 35 and a glass transition temperature of -50 ° C, and 10 parts of N-vinyl caprolactam were mixed together.

After coating the polyester film and irradiating the cathode ray with a dose of 35 kGy, the following sizing values were obtained: 16 70042

Peel strength: 4n / 2 cm; shear strength at 20 ° C: 30 hours; shear strength at 50 ° C: 3 hours.

Comparative Example The following sizing values were obtained for the mixture according to the example of DE-A-23 57 486 without the addition of a photoinitiator after coating the polyester film and irradiating with a dose of 35 kGy:

Peel strength: 4 N / 2 cm; shear strength at 20 ° C: 25 hours; shear strength at 50 ° C: 0.5 hours.

Claims (2)

70042 A process for preparing self-adhesive coatings by coating substrate materials with acrylic acid esters and irradiating the coatings with abundant energy radiation, characterized in that dihydroxypropyl acrylic acid esters are also used as acrylic acid esters and 120% by weight of polymers having a glass transition temperature below 0 ° C and a K value of 20 to 80, and / or b) 0 to 90% by weight of a conventional tackifying resin, wherein (a) and (b): The total amount of n is at least 5% by weight, and the weight percentages of the above (a) and (b) are calculated from the weight of the dihydroxypropyl acrylate derivatives. Process according to Claim 1, characterized in that the mixture additionally contains 2 to 10% by weight, based on the amount of dihydroxypropyl acrylate derivatives, of monomers containing at least two carbon-carbon double bonds.