DE2309372A1 - WATER-SOLUBLE ACRYLESTER POLYMERIZES - Google Patents

Description

Bad i set "; / Lniliu-« Se Sod a · -Fabrik AG

Our reference: O.Z. 29 719 Wd / IG 6700 Ludwigshafen, February 22, 1973

Water-soluble aeryl ester polymers

Pressure-sensitive adhesives for the coating of articles such as labels, adhesive tapes, decorative films and are used in increasing quantities self-adhesive anti-drumming tapes are used. Some of the liquid adhesives still used for this purpose, or else Remoistenable adhesive coatings are becoming more common replaced more by self-adhesive compounds, i.e. pressure-sensitive adhesives. Mixtures, for example, have proven to be the basis for PSAs made of natural or synthetic rubber and tackifying resins, e.g. water-insoluble polyacrylates, or even polyisobutylene and polyvinyl ethers and also polymers or Copolymers of acrylic esters or copolymers of vinyl acetate and ethylene by themselves can be used practically as pressure-sensitive adhesives will.

The polymers and polymer mixtures used as pressure-sensitive adhesives However, they are only soluble in organic solvents and not in water. This is especially a disadvantage if the structures stuck on using pressure-sensitive adhesives are to be removed again, such as labels and if necessary adhesive tapes and decorative foils. There is therefore a need in the art for such PSAs or Pressure-sensitive adhesive polymers that are water-soluble.

It has now been found that water-soluble polymers from (a) 80 to 100 percent by weight of acrylic esters of the general Formula I.

0 _φ / ^R 1

CH ₂ = CH - C - 0 - (CH ₂ ) _n - N ^ - R ₂ Χ ^θ ,

in which R ₁ and R _{2 represent} alkyl groups containing 1 to 3 carbon atoms, R, represents H or an alkyl group containing 1 to 3 carbon atoms, where R ₁ + R ₂ + R ₅ together not more than

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Contains 5 carbon atoms, η for an integer from 1 to 4

and X stand for an acid residue, and

(b) 0 to 20 percent by weight of other aliphatic monomers with a vinyl group,

the polymers in aqueous solution having K values of at least 100 have excellent pressure sensitive adhesive properties.

The new polymers can be composed of one or more monomers (a) and optionally additional monomers (b) in a conventional manner by bulk, solution, emulsion or (reverse) suspension polymerization from the monomers using radical-forming catalysts, redox catalysts or by stimulating the polymerization using high-energy rays. as Monomers of the general formula (I) have salts of Ν, Ν-dimethyl and of Ν, Ν-diethylate dino-ethyl acrylate, in particular their hydrochloride, particularly proven. As monomers (a) of the general formula (I) there are also N, N-dimethylamino- and Ν, Ν-diethylaminopropyl acrylate in question.

As acid radicals X, the monomers of the general formula (I) can, in addition to the preferred chloride ions, also bromide ions, Nitrate ions, hydrosulfate ions, sulfate ions, methosulf at ions and also ions of phosphoric acid. Organic acid residues, e.g. acetate residues or oxalate residues come into question for the monomers (a) practically at most in exceptional cases, since their acidity is generally sufficient for sufficient Salt formation unsatisfied.

As comonomers (b) in the water-soluble acrylic ester polymers usually in amounts of not more than 10 percent by weight, preferably in amounts of 0 to 5 percent by weight, Based on the total weight of the monomers, are polymerized, particularly those vinyl monomers come into question, their Homopolymers result in films that are tacky at room temperature

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are. Of particular interest as comonomers (b) are monoesters of acrylic acid with alkanols containing 1 to 8 carbon atoms and alkanediols containing 2 to 8 carbon atoms, and also vinyl ethers containing 1 to 4 carbon atoms. The acrylic esters and vinyl ethers can be derived, for example, from straight-chain or branched alkanols or alkanediols, and acrylic esters or vinyl ethers of the type mentioned, which are derived from straight-chain alkanols or straight-chain alkanediols, are preferred.

Examples of comonomers (b) are methyl, ethyl, η-butyl, -2-ethylhexyl, -β-hydroxyethyl, -2-hydroxypropyl and ij> -hydroxy-n-butyl esters and vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether called "As an example of one as comonomers (b) in small amounts, even if vinyl esters are less suitable than the aforementioned acrylic esters and vinyl ethers, vinyl laurate should also be mentioned.

The K values, which, as usual, according to H. Fikentscber, Cellulose- Cbemie, Volume 13 (1932) pages 58ff. are determined should generally be over 100, preferably over 120. They are often 120 to 250, mostly 130 to 200, and water-soluble acrylic ester polymers with K values of 140 to 170 are of particular interest as adhesive polymers, homopolymers made from the monomers (a) of the general formula (I) of are of particular interest.

In a particularly advantageous embodiment of the preparation of the new polymers, a solution of the monomers (a) and optionally monomers (b), which contains a customary photoinitiator , is applied in a thin layer on the surface of a flat structure with high-energy rays at room temperature or optionally higher Temperature irradiated. In this way, water-soluble acrylic ester polymers of the type according to the invention with particularly high K values can be produced. In this preferred preparation of the new polymers , an aqueous one is generally used

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Solution, the total content of monomers should be as high as possible and generally between 10 and 90, preferably is between 30 and 75. In some cases, solutions of the monomers (a) and optionally (b) in organic solvents, e.g. lower aliphatic alcohols, such as especially methanol and ethanol, or in Mixtures of predominant amounts of water and minor amounts of organic solvents that can be mixed with it, such as alcohols of the type mentioned, in particular, can be used. The amount of photoinitiator is in general in the range from 0.001 to 1, preferably from 0.01 to 0.1 percent by weight, based on the amount of monomers. Such a solution is applied to a flat structure in a thin layer, the thickness of which is generally between 0.1 and can be 20 mm, irradiated. The flat structure carrying the thin layer is preferably movable arranged under the radiation source. An endless steel belt, for example, can be used as a flat structure if the polymer produced as such and is to be separated from the flat structure after its production. In this In this case, the thickness of the thin layer of the monomer solution is generally between 1 and 20 mm, preferably between 4 and 10 mm. Paper and film webs, e.g. made of polyethylene, polypropylene, polyvinyl chloride, are also used as flat structures. Polyethylene glycol terephthalate, polystyrene or cellulose and cellulose derivatives in question. In this case the thickness of the thin layer is generally between 0.01 and 1 mm, preferably between C.0.5 and 0.2 mm. As a flat structure, for example, part of the Surface of glass or plastic bottles can be used and also in this case the thickness of the thin layer is im same area as when foils or paper webs are used as flat structures. In the latter cases of polymerizing on paper and film webs "or on the surface of bottles, the polymers are obtained in the General firmly adhered to the surface of the planar Formed as a practically finished pressure-sensitive adhesive coating.

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The photoinitiators for this (! "Can remain Compounds, as described in detail, for example, in the book by J. Kosar "Light-Sensitive Systems", John Wiley-Verlag, New York (1956), as well as in DOS 2 009 748 are described, can be used. Examples of special Suitable photoinitiators bind: benzoin ethers, benzil ketals and mixtures of benzophenone and 4,4 '- (N, N-dimethylamino) benzophenone.

High-energy rays are preferably those whose length waves are in the range from 200 to 500 nm. Such rays can be generated in a conventional manner, for example, with carbon arc, mercury vapor, xenon and fluorescent lamps. In the preferred embodiment of the manufacturing process, UV light is usually used as the high-energy rays. The irradiation can be at room temperature or, in some cases advantageous, at elevated temperature, especially at temperatures of 30 to 150 ⁰ C, are preferably carried out from 50 to 100 ⁰ C. If the irradiation is carried out at an elevated temperature, the solvent used, for example water, can thereby be separated off practically simultaneously with the preparation of the polymer.

The new water-soluble acrylic ester polymers are important primarily as essential constituents of pressure-sensitive adhesives. Such PSAs generally contain, in addition to the water-soluble acrylic ester polymers Water and, if necessary, in some cases also small amounts of organic solvents, e.g. lower ones Alcohols such as methanol, ethanol and isopropanol and / or water-soluble ketones and / or ethers such as acetone and dioxane.

The proportion of water-soluble acrylic ester polymers is generally between 5 and 95, preferably between 10 and 35 percent by weight, based on the total pressure-sensitive adhesive. In addition, such PSAs can also in amounts generally between 5 and 90, preferably

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between 90 and 70 percent by weight, based on the total pressure-sensitive adhesive, are water-insoluble pressure-sensitive adhesive polymers, for example based on acrylic ester copolymers of 4 to 8 carbon atoms in the alcohol radical containing acrylic esters, which can be used, for example, in the form of an aqueous dispersion or as a solution. In some cases it is also an addition of minor amounts of natural rubber and / or synthetic rubber, which is also generally is used as an aqueous dispersion is advantageous. Finally, the PSAs can contain additives customary for this purpose other tackifying resins and, in some cases, pigments, fillers and / or common fungicides included in the usual quantities.

Pressure-sensitive adhesives of the type mentioned can advantageously be used for the production of pressure-sensitive adhesive articles, with in general, at least part of the surface of the article with the pressure-sensitive adhesive is usually carried out in a manner customary per se in an application thickness of 0.005 to 0.1, preferably from 0.01 to 0.05 mm, for example using doctor blades applies and the water or the solvent may evaporate at elevated temperature. As an article that for a Should be considered with the pressure-sensitive adhesives especially paper and foil webs of the type mentioned above, anti-drumming tapes, labels, glass and plastic bottles and flooring tiles, e.g. made from polyvinyl chloride, from needle punched fiber tiles or from knobbed carpets, and finally Foam rubber sheets and foamed polystyrene sheets called. It is a particular advantage of using the polymers or pressure-sensitive adhesives of the invention manufactured pressure-sensitive adhesive articles that the pressure-sensitive adhesive layers can be easily removed with water. The hydrophilicity on the other hand, the pressure-sensitive adhesive layers are not so large that the adhesive properties of such pressure-sensitive adhesive articles due to extremely high humidity or accidentally Moisturizing labels, for example, slacken off too much. The PSAs can also in some cases can be used as hotmelt pressure-sensitive adhesives and for the production of glue sticks. - 7 -

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To assess the adhesive properties of PSA, films made of polyethylene glycol teperbalate or of plasticized polyvinyl chloride are coated in the usual manner in the examples in such a way that the application rate is 25 g / m 2. The Bescbicbtungen are dried (50 bar) at 2O ⁰ C under reduced pressure. To test the surface tack, the loop test and the switch test are carried out. To this end with the pressure-sensitive adhesive polymers coated films in 2 cm wide test strips are cut and these strips stored for 24 hours in a climatic chamber at 20 ⁰ C and 65 $> relative humidity.

A) In the loop test, the test strip is put into a loop and clamped in the upper jaw of a tearing machine. The adhesive layer is on the outside of the loop. In the lower jaw of the tearing machine there is a high-gloss chrome-plated metal sheet on which the loop is run at a speed of 150 mm / minute over a length of about 5 cm. It is immediately withdrawn at the same speed and the force required for this is measured.

B) In the peel test , the test strips are glued to a chrome-plated plate and peeled off parallel to the adhesive layer, ie at an angle of 180, and the force required for this is measured. The peel speed is 150 mm / minute and the measurement is carried out immediately and 24 hours after bonding.

C) A shear test is carried out as a measure of the cohesion of the adhesive layer. The test strips are glued to high-gloss chrome-plated sheet metal with an area of 20 × 25 mm. The sheet is clamped vertically and the end of the adhesive tape is loaded with 500 g *. The time is determined until the bond is released under the constant tensile stress of 500 g. The measurement is carried out at 20 ^° C. and 50 ^° C.

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The parts and percentages given in the following examples relate to weight. The specified K values were after H. Fikentscher, Cellulosecbemie _1j5, 59 (1932) in 0.1 percent solution, in 5 percent aqueous NaCl solution determined (k = 10 Κ).

example 1

171 parts of N.N-diethylamino-ethyl acrylate (DA3) are with 21 parts of water mixed. 100 parts of 35 percent strength aqueous hydrochloric acid are rapidly added dropwise with stirring and thorough cooling. The solution is adjusted to pH 6 (DA3 · HCl).

0.014 part of methylolbenzoin methyl ether is added to 100 parts of this solution (MBMÄ) dissolved, the solution poured out in a shallow dish to form a 0.5 cm thick layer and Illuminated for 10 minutes with Osram fluorescent tubes L 40 W / 70 from a distance of 8 cm. The polymer obtained is soluble in water. Its K value is 174.5.

The polymer gives an adhesive film on polyester film with the following adhesive values:

Loop test 0.5 kg / 2 cm

Immediately peeled 0.3 kg / 2 cm

after 24 hours 1.0 kg / 2 cm

Shear test at 20 ⁰ C> 4 days

at 50 ⁰ C> 4 days

Example 2

50 parts of DA3 are dissolved in 200 parts of acetone. About 11 parts of hydrogen chloride gas are passed in through a frit with cooling until an acidic reaction is obtained. The precipitated hydrochloride is filtered off with suction, washed with a little cold acetone and dried. The yield is 95 1 » DA3 · HCl.

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72 parts of DA3 * HCl are dissolved in 28 parts of water, the solution is adjusted to pH 5 with 10 percent aqueous hydrochloric acid and 0.025 parts of benzoin methyl ether (MBE) are added, The solution is irradiated in a layer thickness of 7 mm as described in Example 1 for 8 minutes.

The water-soluble polymer obtained has a K value of 183. Its adhesive properties correspond to those in Example 1 described product.

Example 3

In each 100 parts of the monomer solution described in Example 1 (DA3 · HCl) are in

Sample A 1 part of 2-ethylbexyl acrylate Sample B 3 parts n-butanediol monoacrylate and Sample C x 3 parts 1,4-butanediol monoacrylate

dissolved or emulsified by brief turbine operation. After adding 0.07 parts of benzoin isopropyl ether (BPÄ), like described in Example 1 polymerized.

The polymers obtained are soluble in water and ethanol; the K value is 151 for sample A and 138 for sample B and for sample C 160.

The following adhesive values are determined on polyester film:

Sample A Sample B Sample C

Loop test (kg / 2 cm) 0.3 0.4 0.2

Peel test immediately (kg / 2 cm) 0.2 0.3 0.3

after 24 hours (kg / 2 cm) 1.1 0.9 0.8

Shear test at 20 ⁰ C (days)>4> 4? 4

at 50 ⁰ C (days)>4>4> 4

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Example 4

60 parts of DA3 are dissolved in a mixture of 207 parts of water and 30 parts of 35 percent strength aqueous hydrochloric acid in a polymerization vessel with belts. Thereafter, 3 ecm 2 percent aqueous K ₂ S ₂ Og solution and 3 ecm 1 percent aqueous NaHSO ^ solution are added at 25 ° C. Polymerization is carried out at 25 ^° C. for 1/2 hour and at 50 ^° C. for 1 hour. The polymer solution obtained has a solids content of 5 #; the K value of the polymer is 166.

After spreading onto Weicb-PVC foil, a film is also created obtain the following adhesive properties:

Loop test 0.8 kg / 2 cm

Peel immediately 0.4 kg / 2 cm

after 24 hours 1.4 kg / 2 cm

Shear test at 2O ⁰ C for 4 days

at 50 ^° C. for 4 days

Example 5

14 _t 3 parts of Ν, Ν-dimethylaminoethyl acrylate (DMA2) are mixed with 1 part of water and reacted with 10 parts of 35 percent aqueous hydrochloric acid to form the hydrochloride. The pH was adjusted to 4. 0.004 parts of MBMÄ are added to the solution. It is then photopolymerized as indicated in Example 1. The aqueous solution obtained has a solids content of 75 percent by weight. The polymer has a K value of 192.3.

After application (approx. 50 g / m 2) to commercially available paper for labels, an adhesive layer with the following adhesive values is created obtain:

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Loop test (kg / 2 cm) 0.2

Peel test immediately (kg / 2 cm) 0.2

after 24 hours (kg / 2 cm) 0.8

Shear test at 20 ⁰ C (days)> 4

at 50 ⁰ C (days)> 4

Example 6

70 parts of N-trimethylammonium ethyl acrylate chloride are used in Dissolved 30 parts of water, added 0.045 parts of MBMA and poured in 5 mm thick Slides, as indicated in Example 1, pbotopolymerized. The polymer solution obtained had a solids content of 75 percent by weight. The K value of the polymer is 147.

After application to polyester film, the following adhesive values are determined:

Loop test 0.7 kg / 2 cm

Peeled immediately 0.6 kg / 2 cm

after 24 hours 1.3 kg / 2 cm

Shear test at 20 ⁰ C> 4 days

at 50 ⁰ C> 4 days

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Claims (4)

Claim e / 1, water-soluble polymers from ¹ ^ (a) 80 to 100 percent by weight of acrylic esters of the general formula (I) τ, CH ₂ = CH - C - 0 - (CH ₂ ) _n - N ^ -R ₂ Χ ^θ , ^R 3 in which R ₁ and R _{2 are alkyl groups containing 1 to 3 carbon atoms, R 1 is} H or an alkyl group containing 1 to 3 carbon atoms, where R 1 + R ₂ + R, together not more than 5 C- Atoms contain, η for a whole η
Z _a HL by 1 to 4 and X is an acid residue, and (b) 0 to 20 percent by weight of other aliphatic monomers having a vinyl group, the polymers in aqueous solution having K values of have at least 100. 2. Process for the preparation of polymers according to claim 1, characterized in that a solution of monomers (a) and optionally of monomers (b) which contains a conventional photoinitiator is applied in a thin layer on the surface of a flat structure with high-energy rays Irradiated at room temperature or optionally at an elevated temperature. 3. PSAs containing water-soluble polymers according to Claim 1. 4. Use of pressure-sensitive adhesives according to Claim 3 for the production of pressure-sensitive adhesive articles by coating at least part of the surface of the articles with the PSAs in a conventional manner and optionally evaporation of solvents. Badische Anilin- & Soda-Fabrik AG 409836/0551