NL8103932A - LINE MIX WITH "EASY-CLEAN" PROPERTIES BASED ON VINYL ACETATE. - Google Patents

Description

3, VO 2238 * Adhesive mix with "easy-clean" properties based on "vinyl acetate base.

Improved emulsion adhesives based on vinyl acetate homo- or eopolyners, which adhesives are characterized by excellent "easy-clean" properties, are prepared by adding special water-soluble ion-active salts. Moreover, when such salts are added to those emulsion adhesives suitable for rewetting applications, the resulting products are also characterized by improved "lay-flat" behavior.

_ Vinyl acetate based adhesives are used for a wide variety of industrial applications. For example, they are used in rewetting, stenciling, laminating, packaging and other high speed gluing applications. It will be appreciated that high speed processing of these adhesives results in the formation of deposits of dried glue on the various machine parts, which finally interferes with machine processing. Saar-15 cm is emphasized by glue users on the need to remove these deposits quickly and easily with water (a property referred to as "easy-clean"), thereby minimizing stopping time . So far, the "easy-elean" properties, e.g. achieved by using relatively large amounts of polyvinyl alcohol. However, polyvinyl alcohol is expensive, while in some cases its use may undesirably thicken the adhesive or the polyvinyl alcohol may react unfavorably with the substrate to be glued, such as in the case of "patch-gumming" of polystyrene boxes in the manufacture of envelopes In a related area, certain vinyl acetate emulsion adhesives also require a degree of water sensitivity, allowing rewetting applications. The use of these aqueous emulsions for the preparation of re-wettable glues, however, results in the paper fibers swelling and the substrate flowing smoothly therefrom, a problem which becomes even worse upon drying. Attempts have been made to avoid or reduce the wrinkling by adding various wetting agents or plasticizers. To date none of this has resulted in the production of a satisfying aqueous lay-flar adhesive. 2nd last 8 1 0 0 9 3 2 * - "v * 2 the property was obtained only by the wrinkled substrate over knife edges or rollers to destroy the continuity of the adhesive film and thereby allow the substrate to regain its flat configuration.

The present invention provides aqueous emulsion adhesives based on vinyl acetate homo- and / or copolymers, which adhesives are characterized by improved "easy-clean" properties. The invention also provides certain adhesives which are particularly suitable for applications involving patch gumming or stenciling. Furthermore, the invention provides certain glues which contain partially hydrolyzed polyvinyl alcohol, which glues, in addition to having "easy-clean" properties, are also suitable as re-wettable glues, which retain their "lay-flat" configuration even after keep drying. The addition of certain water-soluble ion-active salts to the conventional vinyl acetate aqueous emulsions provides the excellent "easy-clean" and, in some cases, "lay-flat" behavior.

The aqueous adhesive mixture, which is characterized by "easy-clean" properties, comprises per 100 parts by weight of the total mixture: 50 - 99% of an aqueous emulsion, of vinyl acetate homo or copolymer, 0.5 - 15 parts of calcium chloride, calcium nitrate, magnesium chloride, magnesium nitrate, aluminum chloride, aluminum nitrate, ammonium chloride, ammonium acetate, potassium acetate or mixtures thereof, 0 -35 parts of wetting agent, 0-35 parts of plasticizer, 0-35 parts of solvent 25 and 0-20 parts of water-soluble protective colloid, in which the total of the last four components is 0-1 + 9.5 parts per 100 parts of the total mixture. The adhesive mixture suitable for patch gumming operations consists per 100 parts by weight of the total mixture of: 50 - 89.5 parts of an aqueous vinyl acetate copolymer emulsion, 0.5 - 15 parts of calcium chloride , calcium nitrate, magnesium chloride, magnesium nitrate, aluminum chloride, aluminum nitrate, ammonium chloride, ammonium acetate, potassium acetate or mixtures thereof, 5-20 parts of plasticizer and 5-35 parts of humectant. The re-wettable adhesive mixture, which is characterized by improved "lay-flat" properties, consists per 100 parts by weight of the total mixture of: 50-89.5 parts of an aqueous emulsion of vinyl acetate homo- or copolymer. 5 - 15 parts of calcium chloride, calcium nitrate, magnesium chloride, magnesium nitrate, 8103932 V * 3 aluminum chloride, aluminum nitrate, ammonium chloride, ammonium acetate, potassium acetate or mixtures thereof, 5-15 parts partially hydrolysed polyvinyl alcohol and 5-30 parts humectant.

The special salts to be used according to the invention can generally be classified as hygroscopic, deliquescent, water-soluble ionic salts. Calcium chloride is particularly preferred for effectiveness, concentration, cost and availability. , calcium nitrate, magnesium chloride, magnesium nitrate, aluminum chloride, aluminum nitrate, ammonium chloride, ammonium acetate and potassium acetate ♦ Mixtures of these salts or mixtures of these salts with other inorganic salts not mentioned above may also be used The amount of salt will vary depending on the of the particular salt selected, the vinyl acetate base, as well as the end use for which the system is intended, however, the amount will generally be between 0.5 and 15 parts per 100 parts of the total mixture.

The use of the salts of the teachings described herein may benefit any conventional vinyl acetate-based emulsion adhesive. Compositions for such emulsions are known and generally include vinyl acetate copolymer emulsions, as well as vinyl acetate emulsions copolymerized with up to about 50 parts of a copolymerizable monomer or mixtures thereof. Especially in industrial applications, copolymers of vinyl acetate with ethylene, as well as with acrylate and maleate esters, are widely used. These emulsions are commercially available or can be readily prepared and are generally used in the form of aqueous emulsions with a solids content of about 55%, although higher or lower solids concentrations may also be used. Considering the relative proportions of the components present in the adhesive compositions of the invention, where amounts are calculated per 100 parts by weight, it will be appreciated that the water used in the vinyl acetate emulsions will be calculations is included.

It will be appreciated that the adhesives according to the invention are formulated according to known techniques and, depending on the desired application, plasticizers, such as e.g. polyethylene glycol, dibutyl 8 1 0 3 832 # - k phthalate, butyl benzyl phthalate, propylene glycol dibenzoate, triethylene glycol polyester of benzoic acid and of phthalic acid, alkyd plasticizers,. etc .; humectants, such as glycerol, triethylene glycol, propylene glycol and urea; water-soluble polymers or protective colloids, such as polyvinyl alcohol, polyvinylpyrrolidine, polyvinylpyrrolidine acetate copolymer, polyacrylamide, etc .; solvents, such as toluene, 1,1,1-trichloroethane, etc., as well as mixtures of any of the above substances. Generally, the wetting agents, plasticizers and solvents may be present in amounts ranging from 0-30 parts per 100 parts of the total mixture, using the protective colloid in amounts of up to about 20 parts. In all cases, however, the total amount of the above-described additives to be used, if desired, will be less than about 5 5 parts per 100 parts of the total mixture.

In particular, the vinyl acetate emulsion adhesives suitable for use in rewetting applications will usually contain about 5-15 parts of partially hydrolyzed polyvinyl alcohol and 5-30 parts of wetting agent per 100 parts of total mixture.

The alcohol is often used in a water-dissolved form, the easiest being made with 20+ solutions. (The water present in solutions is not included in the calculations listed here).

In addition, other additives known in the field of adhesives may also be present in small amounts.

Among these additives, e.g. include: fillers, such as clay and chalk; anti-oxidants, such as butylated hydroxyanisole and butylated hydroxytoluene; preservatives, such as sodium benzoate and formaldehyde; lubricants; Wash; pigments; dyes; anti-foaming agents; taste and / or odor improving agents; chelating agents; Anti-corrosion agents, fragrances; etc.

The resulting adhesive mixtures of the invention are usually used with a solids content of at least about $ 30, preferably $ 50 or more, although additional water can be added afterwards through the addition of protective colloids or to the final viscosity for good machining processing.

It will be appreciated that the specific compositions selected, as well as the choice of additives, if utilized, will vary depending on the final application for which the particular adhesive or coating is to be used.

Adhesives formulated with these particular salts according to the teachings herein mentioned can be applied using suitable conventional techniques. The adhesives do not show any significant change in application, machining or adhesive properties, while they require only effortless water cleaning of the excess dried adhesive residues on the machines and other application equipment.

It should be remembered that certain salts, including some of the salts the use of which has been described herein, have previously been used as stabilizers and to "pasting" starch-based adhesives (premature curing or formation of the adhesive in a 1p reservoir, in which it is stored) or to modify soft pressure sensitive emulsions of polyacrylate and related eopolymers, in which emulsions the salt serves to cross-link the dried film via carboxyl or other reactive groups on the polymer, wherein greater cohesive values and greater insolubility are obtained, properties which are opposite to those required in the present invention. For this reason, adhesive systems containing axial carboxyl or related functional groups which react with metal ions have not been used for use in the invention.

Further details of the invention, as well as examples of compositions, follow below. In the examples, all parts are parts by weight.

Example I

In order to graft the "easy-elean" property thereby achieved, admixtures were prepared using a vinyl acetate copolymer emulsion (55% solids) and varying amounts of calcium chloride. The adhesive mixtures were composed as follows:

Samples (parts)

A_B_C_D

35 Yinylacetate-hcmcpolymer-enulsion IOC 100 100 100 dale iunchlc ri de 10 5 0.5 8103932 »6 __

The glues were tested for "cleaning" properties by pouring 1 ml aliquots of each mixture onto glass plates and allowing the coatings to dry and age for 1 week. Then drops of water were applied to each film and rubbed comparatively Samples A, B and C containing the calcium chloride salt disintegrated easily, with mixtures A and B containing higher amounts of salt disintegrating almost immediately, while control sample D had to be rubbed for a long time to remove to accomplish.

Example IX

Other conventional adhesive mixtures based on vinyl acetate homopolymer and copolymer emulsions with 55% solids were prepared as follows:

Samples (parts)

15 ABCDEFG H

Vinyl acetate homopolymer emulsion 100 100 100 100 100 100 - -

Vinyl acetate-acrylic copolymer ------ 100 100

Butyl benzyl phthalate (Sanitizer 160-

Monsanto) 10 10 6¾ 6k kh - - 20 Calcium chloride 20 - - 5 -

Magnesium chloride - - 18 - 18 - 1,1,1-Trichloroethane 20 20 -

The adhesives, designated A, C, E and G, when tested for cleaning properties, could be easily removed from the glass plates using only water as described in Example I. Similarly, samples B, D, F and H could not be easily removed.

Example III

It is in sample A of example. The described adhesive mixture was prepared, replacing the calcium chloride with calcium nitrate, magnesium chloride, magnesium nitrate, aluminum chloride, aluminum nitrate, ammonium chloride, ammonium acetate, potassium acetate, a mixture of equal parts of calcium chloride and magnesium chloride or a mixture of equal parts sodium chloride and calcium chloride. All samples had the same "easy-clean" characteristics as those of the sample prepared with calcium chloride.

8103932 ** 3? ** **

Example 17

The following blends are examples of glues which can be used for patch gumming or stenciling applications, eg for window envelope glues, in which poly-5 styrene slotting or related films were attached to paper envelopes. High Speed Stenciling Techniques These glues were generally formulated using aqueous vinyl acetate copolymer emulsions containing 5-20 parts of plasticizer and 5-35 parts of humectant per 100 parts of the total mixture.

Samples (parts)

A B C D

Vinyl acetate maleate cc polymer - - 100 100

Vinyl acetate-ethylene copolymer emulsion 15 (55 # solids} 100 100 - -

Triethylene glycol polyester of benzce and phthalic acid (Hercoflex 900, a product of Kercules Chemical Co.} 23, ^ - 23, ¼ 2k 2h

Glycerol 28.1 28.1 6b 6k 2Q Magnesium chloride 3.1 - 10 -

Samples A and C containing magnesium chloride could be easily cleaned with water when tested, while samples 3 and D containing no salt had to be rubbed extremely strongly to remove the dried glue.

Example 7 (¾ Similarly, various adhesive mixtures were prepared which could be used for rewetting applications. Subsequently, calcium chloride was added to such systems to achieve the "easy-clean" properties thereby achieved, and additionally the "lay-flat" properties.

8103932 8 _Samples (parts) _

ABCDEFGHIJ

Vinyl acetate homopolymer- 100 100 100 100 100 100 100 100 100 100 emulsion (55 # solids) 5 Glycerol 20 20 20 20 - - 10 10 20 20 k0% rs polyvinyl alcohol - 20 20 30 30 - - 20 20 50 50 hollow solution (88 # hydrolysed)

Polyoxyethylene glycol (600 MW) - - - - 1U 1U 10 ΙΟ Ι 0 (Carbovax 600-Union Carbide)

Polyvinylpyrrolidines / - - - - 6 6 ---- vinyl acetate (1: 1 ratio)

An alkyd plasticizer (Resoflex - 3 3 ------ R2 $ 6 - Cambridge Industries) 15 Calcium chloride 10 - 10 - 10 - 10 - 10 -

All of the above adhesive samples were coated onto 5.3 W-3 kg / ream standard gumming stock paper in the machine direction and air dried and allowed to cure overnight. Then pieces of 15.2¼ x 11.3 cm were cut in the direction of the machine and observed daily for one week (with the coated side up) in order to show the wrinkle properties or relative "lay-flat" properties. take. The samples containing the appropriate salt began to show a slight convex ripple (considered desirable from a lay-flat point of view), while the samples not containing the salt developed a slight concave ripple. At the end of 1 week, the samples with the salt were still slightly convex, while the control samples without the salt were significantly concave, ie, they had extremely strong ripples.

The "easy-clean" test described in Example I was also repeated with all of the above mixtures, those samples containing the salt exhibiting "easy-clean" properties, while the control samples were very difficult to clean.

Example VI

The mixture described in sample A of example V became a number of different salts instead of calcium chloride. Thus, mixtures were prepared with magnesium chloride, magnesium nitrate, calcium nitrate and a mixture of equal parts of calcium chloride plus ammonium acetate. When tested in the manner described in Example V, all mixtures had the desired "easy-clean" and "lay-flat" properties.

In summary, advances have been made to provide aqueous glues which are characterized by "easy-elean" properties and, in some cases, by improved "patch-gumrning" and "lay-flat" properties.

8103 932

Claims (5)

An aqueous adhesive mixture, characterized by "easy-clean" properties and per 100 parts by weight of the total mixture consisting of: a) 50 - 99% of an aqueous vinyl acetate homo- or copolymer emulsion; H) 0.5-15 parts of calcium chloride, calcium nitrate, magnesium chloride, magnesium nitrate, aluminum chloride, aluminum nitrate, ammonium chloride, ammonium acetate, potassium acetate or a mixture thereof; c) 0 to 35 parts of a preservative; d) 0-35 parts of plasticizer; E) 0-35 parts of solvent; f) 0 to 20 parts of water-soluble protective colloid; the total of components (c), (d), (e) and (f) being 0 - k9.5 parts by weight per 100 parts of the total mixture. Glue mixture according to claim 1, wherein the emulsion of the part (a) is a vinyl acetate homopolymer emulsion. The adhesive mixture according to claim 1, wherein the emulsion of the portion (a) is a vinyl acetate-ethylene copolymer emulsion. k. Glue mixture according to claim 1, wherein the salt of part (b) is calcium chloride or magnesium chloride. 20 5 · An aqueous "easy-clean" adhesive mixture, per 100 wt. parts of the total mixture consist of: a) 50-8995 parts of an aqueous vinyl acetate copolymer emulsion; b) 0.5-15 parts of calcium chloride, calcium nitrate, magnesium chloride, magnesia nitrate, aluminum chloride, aluminum nitrate, ammonium chloride, ammonium acetate, potassium acetate or mixtures thereof; o) 5-20 parts of plasticizer and d) 5-35 parts of preservative agent. 6. A glue mixture, which can be re-wetted, characterized by improved "lay-flat" properties and per 100 parts by weight of the total mixture consisting of: a) 50 - 89.5 parts of an aqueous vinyl acetate homo- or copolymer emulsion; 8103932 b) 0.5-15 din calcium chloride, calcium nitrate, magnesium chloride, magnesium nitrate, aluminum chloride, aluminum nitrate, ammonium chloride, ammonium acetate, potassium acetate or mixtures thereof; c) 5-15 parts of partially hydrolyzed polyvinyl alcohol; and d} 5-30 parts of humectant. 7 · An improved aqueous vinyl acetate emulsion adhesive, the improvement of which is to add 0.5-15 dia. Of calcium chloride, eal-10 calcium nitrate, magnesium chloride, magnesium nitrate, aluminum chloride, aluminum nitrate, asnonium chloride to each 100 parts of the total adhesive base. , armonium acetate, potassium acetate or mixtures thereof, whereby "easy-clean" properties are obtained. 8103032