DE2715434A1 - ADHESIVE, GLUING METHODS AND THE SUBSTRATES INCLUDED WITH THEM - Google Patents

Description

The invention relates to adhesives which are essentially polyvinyl alcohol or an ethylene / vinyl alcohol copolymer, a crystalline solvent for the polymer component (such as Urea, thiourea, acetamide, ammonia formate, etc.) and contain a diluent to lower the viscosity (such as water, glycols, etc.). The adhesives are especially for cellulosic ^ substrates suitable and have at ambient temperature very good water resistance. They can be easily processed into a pulp again in hot water.

The invention relates to compositions or compositions based on polyvinyl alcohol. In particular, it relates to polyvinyl alcohol or an ethylene / vinyl alcohol copolymer, a crystalline one Adhesives containing solvents for the polymer and diluents to lower the viscosity.

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In JA-OS 12851/72 v / iel the production of molded articles from polyvinyl alcohol is described. In this process, an aqueous polyvinyl alcohol solution of up to 20% by weight is produced. Based on the weight of the aqueous solution, 5 to 55% by weight of urea are then added to the solution. A uniform force is then applied to the aqueous solution by mechanical stirring. The polyvinyl alcohol / water / urea mixture used in this process contains 0.1 to 19 # polyvinyl alcohol, 55 to 95 # water and 5 to 3% urea, all percentages being based on the total weight of the solution. The shaped objects produced by this process are suitable as very tough, non-woven or non-knitted, flat textile materials, as flakes for mattress inserts or wadding. They can also be used as filaments after the molded articles are split. There is no suggestion of the utility of any of the aqueous solutions or the molded articles as adhesives.

In U.S. Patent 3,313,637, models are described which can be easily removed from their molds. The models consist of a main part by weight of finely divided, crystalline material (such as urea), a smaller proportion by weight of finely divided organic material (such as polyvinyl alcohol) and a liquid solvent for the crystalline material (such as water / water). Example 1 describes the use of a composition which contains 85% urea, 10Sa polyvinyl alcohol and 5% water. However, there is no indication of the use of adhesives in general or as hotmelt adhesives in particular; on the contrary, it is emphasized that after the models have been pressed, they can easily be extracted from the matrix in which they are formed.

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The invention relates to an adhesive or an adhesive composition which essentially contains or consists of: about 2 to 35% by weight of a polymer from the group consisting of polyvinyl alcohol and ethylene / vinyl alcohol copolymers which contain at least 50 mol% of vinyl alcohol; about 10 to 50% by weight of at least one solvent for the polymer, the solvent being crystalline at 40 ° C and being selected from the group: urea, solid alkyl-substituted ureas containing a total of up to 9 carbon atoms, thiourea, biuret, £ - Caprolactam, solid aliphatic amides containing up to 6 carbon atoms, solid polyhydric compounds, and ammonium carboxylate salts; about 5 to 80% by weight of at least one diluent for reducing viscosity, from the group consisting of water, liquid polyhydric compounds, liquid alkyl-substituted ureas having up to 9 carbon atoms in the alkyl group, liquid aliphatic amides containing up to 6 carbon atoms, and dimethyl sulfoxide; and from 0 to about 60% by weight of an extender selected from the group consisting of starch, dextrin, clay, silica, carbon black, talc, calcium carbonate, barium sulfate and vinyl polymer latices, provided that when the diluent for viscosity reduction is in an amount of over 45% by weight is present, the adhesive composition is present as a suspension and the polymer is polyvinyl alcohol which is ^{dispersed in the heat at a temperature of 70 to 190 °} C. in a liquid solvent which contains 42 to 100% by weight of methanol, 9 to 13% by weight of water and 0 to 45% by weight of a solvent from the group consisting of 2 to 5 carbon atoms containing monohydric alcohols, esters, ketones, ethers, hydrocarbons and chlorinated hydrocarbons, in which the polyvinyl alcohol is insoluble, has been treated so that " the cold water soluble content of polyvinyl alcohol is reduced, while its solubility in water at 80 to 100 ° C is retained.

The invention also relates to structures that contain cellulose Substrates with the adhesive according to the invention

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material compositions were glued, included.

In the present application, the term "or" may ^{mean! L} ia essentially comprising consisting essentially of "means that only those non-specified components are present, do not materially affect the basic properties and novel characteristics of adhesive compositions according to the invention. Such ingredients such as wetting agents, curing agents, etc. . be.

According to the invention, adhesives based on polyvinyl alcohol were used (PVA) and ethylene / vinylallcoliol (E / VOH) copolvraeren, containing at least 50 mol% VOH. These Adhesives can be applied by coating, spray or Hot melt processes are used. The compositions, which may or may not be homogeneous, represent different ones new types of adhesive system for bonding cellulosic materials. All adhesive compositions or compositions contain at least the polymer, a crystalline solvent for the polymer and a diluent to lower the viscosity, hereinafter also referred to as "viscosity-lowering diluent" for the sake of simplicity referred to as.

A large number of additional extenders or extenders By-pass means (these terms are used in the present Registration used synonymously), such as starch, dextrin, clay, silicon dioxide or silica, carbon black, talc, calcium carbonate, Barium sulfate as well as vinyl polymer latices (such as polyvinyl acetate and vinyl acetate / ethylene copolymer emulsions) and also mixtures these materials can be incorporated into the adhesive mixtures, so that one has a wide range of applications and maintains a variety of adhesive properties.

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The polymer component acts as a binder and contributes to Adhesive bond strength and water resistance. The crystalline Solvent for the polyvinyl alcohol or the ethylene / vinyl alcohol copolymer acts as a solvent for the Polymer when the invention hates as hot melt adhesives prepared or produced. It also acts as a viscosity reducer and gives some of the compositions described later describe "setting" or "quick sticking". Are the compositions as If hot melt adhesive is used, then the diluent for the .Viskositätserkiedrigung has the role of a viscosity and Melting point depressant, and as such it improves the handleability and melt stability of the molten one Adhesive.

The adhesive compositions described in the present application can be according to a variety of. 'Because of the fact that they can be applied to cellulosic materials within a wide temperature range, depending on the physical form of the adhesive. More specifically, the adhesives from room temperature (about 20 ⁰ C) to a temperature as high as 135 ° C or at any intermediate temperature employed v / ground.

The compositions according to the invention are grounded in the molten state or used as a hot melt adhesive, they are homogeneous and "set" very quickly when cooled. This setting property results in a "fast adhesion" or a "fast adhesion" or * a "fast adhesion". This is a unique one Feature of the melted, homogeneous adhesive systems according to the invention, which is in sharp contrast to the properties known polyvinyl alcohol adhesives, which are used when cooling result in weak, non-adhesive or non-sticky bonds. The term "adherence" or "stickiness" (the angled

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The Saxon expression for this, as it has also become naturalized in Germany, is "Tack") is defined by Skeist (Ref. Handbook of Adhesives, p. 63, Reinhold, 1962) as the "stickiness" of an adhesive that it shows and represents its ability to stick on contact. \ Ίβηη the adhesive has this property to a high degree, it is said that it "sticks quickly" or "sticks quickly" (the Anglo-Saxon expression is "quick tak"). For purposes of discussion, "rapid tack" is defined as the time, in seconds, required for the adhesive to develop a fiber tear bond on a cellulosic substrate in the standard T-peel test. For adhesives that are used for corrugated cardboard or for corrugated cardboard. Material used or used for gluing cardboard boxes, a "quick tack" of 1 to 3 seconds is the preferred range, with a range of 0.5 to 10 seconds being acceptable. The molten, homogeneous adhesive systems according to the invention exhibit rapid adhesion which is within the acceptable range. Range. Adhesives containing urea or thiourea as the main crystalline solvent for the polymer exhibit "quick tack" which is within the preferred range.

The molten, homogeneous adhesives of the present invention can be easily distinguished from mixtures which have only one of the two essential solvent and diluent components, i.e. those that contain only that crystalline solvents or the viscosity reducing diluent contain. Such two-component systems are characterized by very poor melt stability (e.g. PVA / urea mixtures), excessive and unstable application viscosities (e.g. PVA / urea or PVA / thiourea mixtures) and failure to "stick" through crystallization on cooling (e.g. PVA / Viasser or PVA / N-Hethyl- - pyrrolidone mixtures). Solutions that contain 20% by weight

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or more polyvinyl alcohol in common solvents. (2.BJ Water, dimethyl sulfoxide, N-methylpyrrolidone) contain excessive high viscosities and are very likely to gel on cooling.

If the above-described adhesive mixtures are kept in the molten state, normally at 100 to 135 ^° C., for extended periods of time, it is recommended that they be stored in tightly closed containers to avoid loss of the viscosity-reducing diluent. If there is an excessive loss of diluent, the melt becomes progressively more vesicular, due to the formation of ammonia, which is formed by the reaction of polyvinyl alcohol and urea as the temperature rises.

Adhesive mixtures and blends that are not homogeneous melts can be produced. These can be conventional coating method using bsi temperatures which are lower than used in the molten, homogeneous compositions v / ground, for example, applied in the range of 40 to 8O ⁰ C v / ground. These adhesive mixtures are viscous systems (up to 20,000 cP. At 70 ° C) and contain an extender or solvent as an additional component. In general, they have lower viscosities than the molten, homogeneous systems described above. Solutions of only one polymer, ie of polyvinyl alcohol in the diluent (eg V / water), of about 20 wt. # Or more polymer would have an extremely high viscosity. In the heterogeneous adhesive mixtures according to the invention, the crystalline solvent acts as a viscosity-reducing agent, with which the high viscosity is eliminated, which would occur if it were not present. These heterogeneous systems do not exhibit "set" or "quick tack" as quickly as the molten, homogeneous compositions, but they do give water-resistant fiber tear bonds after setting. Of the

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the full advantage of the adhesiveness appears when the diluent is used to reduce viscosity, usually water, after the application of the adhesive, is removed, either by evaporation or by heating, such as this is the case with many known, solvent-containing adhesive systems. These systems also cost significantly less than the currently known polyvinyl alcohol adhesives.

In a further embodiment of the present invention, a particularly preferred type of polyvinyl alcohol is used. The polyvinyl alcohol was heated at a temperature of 70 ° to 190 ⁰ C as a dispersion in methanol and optionally water and 2 to 5 carbon atoms containing monohydric alcohols, esters, ketones, ethers, hydrocarbons and chlorinated hydrocarbons, in which the polyvinyl alcohol is insoluble, for Increased its crystallinity, which is recognizable by a reduction in the cold water solubility, treated. This kind of polyvinyl alcohol has a content of cold-water soluble substances under 10 Gew.?6 at 25 ° C, while its solubility in water is maintained at 80 ° to 100 ⁰ C. Such polyvinyl alcohol products and methods of making them are described in U.S. Patent 3,654,247.

Using this type of polyvinyl alcohol can be heterogeneous Adhesive systems with low viscosities (up to 2000 cP. At 70 ° C) and stable suspensions can be produced. In this state, these can be stored for long periods at room temperature. These systems are suspensions of finely divided polyvinyl alcohol in a solution of the crystalline solvent (preferably urea) in the diluent to lower the viscosity (preferably water). The finely divided PVA used in this system is during remain suspended long times after the initial dispersion during manufacture. A permanently stable suspension / Sion during use can be maintained with a minimum of agitation, such as by gentle agitation or during of flowing or pumping. One can also like a hydrocolloid Guar gum, suspension and / or redispersion auxiliaries, select

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Use periods of static storage, e.g. overnight storage. The resulting suspension can be (about 20 ⁰ C) was applied from room temperature to about 60 ° C to cellulose-containing materials or applied thereto. For this purpose, processes known per se, such as spray coating, roller coating, knife coating processes or other emulsion coating processes, can be used. If the adhesive additives are used by these methods, they adhere firmly as a coating to the cellulosic material when they are air-dried. They can be stored indefinitely until their adhesiveness is activated by further heating. In this form, the adhesive compositions according to the invention are distinguished by heat-activatable systems.

In addition to the requirement that specially treated polyvinyl alcohol be used in the adhesive compositions according to the invention when activatable, stable suspensions with low viscosity are produced, it has been found that all commercially available, investigated grades of polyvinyl alcohol are suitable as blending components. These grades include both fully hydrolyzed (ie, about 99 / S or higher hydrolyzed) and partially hydrolyzed (etvra 88? O) species, which correspond to a degree of polymerization (DP) in the range of about 300 to 2000 (number average basis) as well as fully hydrolyzed copolymers of polyvinyl alcohol (including those containing such as kfa methyl methacrylate comonomer) with a similar DP range. The viscosity (determined at 20 ⁰ C using a 456igen aqueous solution) of the polyvinyl alcohols, determined in the blends is in the range of about 4 to about 65 cP. Preferably the viscosity should be about 10 to about 65 cP. be.

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The polyvinyl alcohol that is preferred as a component in the adhesives discussed, regardless of whether it is in accordance with U.S. Patent 3,654,247 or not is one 99? Jige hydrolyzed quality with a D? from SOO and one Viscosity (20 ° C) from 12 to 14 cP. as a 4% aqueous solution. The E / VOH copolymers suitable for the mixtures according to the invention contain at least about 50 MoI-Jo VOH units.

The amount of polyvinyl alcohol or E / VOH copolymer in the mixtures according to the invention can be in the range from about 2 to 35 % by weight . There should be about 10 to 35 weight percent polyvinyl alcohol in the molten, homogeneous systems of the present invention. The use of such amounts of polymer results in firm bonds or bonds in the dry state. In the inventive viscous, heterogeneous embodiment, the polymer content should be about 5 are "used up to 25 wt.% Polymer. Below about 5% yield, a sufficient adhesiveness for a satisfactory bond, whereas, mixtures containing greater than about 25 / a, for a satisfactory handling and An application of the adhesives to substrates are too viscous. Stable suspensions with low viscosity can be produced according to the invention with about 2 to 35% by weight of polyvinyl alcohol. Polymer contents below about 2% do not result in water-resistant bonds, whereas concentrations above about 35/0 not only are economically unsuitable, but continue to eliminate the suspension properties and result in a paste-like consistency.

The adhesives according to the invention show excellent water resistance under ambient conditions, but are in hot water easily repulpable to a pulp. The water resistance at ambient temperature is determined according to the layer or layer separation test, ASTM-D 1023. Accordingly, they can be used anywhere as hot glue

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used where cheap, wax-free systems are required. They are suitable for bonding cellulose-containing materials in wet ambient conditions. As such, they can be used as adhesives. can be used for corrugated cardboard or corrugated material. If they are used as a stable suspension with low viscosity, they can be used as post-activatable cardboard and housing or box or cardboard adhesives for sealing, which are inexpensive. In these systems, fiber tearing bonds are obtained when the polymer concentration in the adhesive mixture is 2.% or more, calculated on a dry weight basis.

The behavior at high humidity is determined by aging the bonded structures at 905% relative humidity for 1 to 2 hours. It is found to be very good. For example, fiber tear bonds are found in tests with conditioned paperboard samples made with molten, homogeneous adhesive containing 2O5S PVA (calculated on a dry weight basis). Bonded structures are made with a stable, low viscosity suspension adhesive containing as little as 2% of the PVA described in US Pat. No. 3,497,487. After immersion in water, fiber tear bonds are obtained for at least 24 hours.

The crystalline solvent for the polymer component must be meet the following requirements: (1) it must be crystalline at 40 ° C; (2) it must act as a solvent for the polymer act, i.e. it. must be at least 5 percent by weight of the latter with or dissolve above the melting point of the solvent; and (3) it must be miscible with the diluent to lower the viscosity. It was found that the following compounds meet these requirements: (1) urea; solid, alkyl-substituted ureas with a total of up to 9 carbon atoms

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contain, such as methyl urea (melting point 95 to 93 ° C.), ethyl urea (melting point 92 ° C.), 1,1-diethy! urea (melting point 112 ° C.), thiourea; Biuret and ε-caprolactan; (2) solid aliphatic amides containing up to 6 carbon atoms, such as acetamide, propicnanide, butyramide; (3) solid polyhydric compounds, v / ie pentaerythritol, sorbitol, mannitol and tris (hydroxymethyl) aminomethane; and (4) ammonium carboxylate salts such as asmonlum formate. In the above description, "solid" means that the specified compound is in its solid state ^{at 20 ° C.}

Urea is preferred as a crystalline solvent for the polymer at the most, mainly because its melting point (132 ° C) is within the preferred B _e Reich 75-175 C because of its lower hygroscopic nature. E-caprolactam is also a preferred crystalline solvent. Thiourea is also preferred, although it has the property of corroding stainless steel devices.

The crystalline solvent for the polymer should be in a Amount present from about 10 to 80 wt. $ 5. Under this Range does the product become too viscous, i.e. shows poor "adhesion", whereas concentrations above 80 ?! . on the water resistance of the adhesions obtained at ambient temperature have an adverse effect.

The amount of crystalline solvent in the various adhesive forms according to the invention is v / ie follows: about 40 to 80% by weight in the melted, homogeneous mixtures; about 10 up to 45% by weight in the viscous, heterogeneous mixtures and about 15 to 68% by weight in the stable, low viscosity suspensions.

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The adhesive mixture according to the invention contain, in addition to the binding polymer and the crystalline solvent, a diluent for reducing viscosity, which is completely compatible, regardless of the state of the adhesive mixture, ie in molten, homogeneous form, viscous, heterogeneous form or as a stable suspension with low viscosity. When used in molten, homogeneous or viscous, heterogeneous mixtures, the term "viscosity lowering diluent ¹¹ " means that this component decreases the viscosity of the mixture, ie the viscosity of a molten mixture containing the polymer, crystalline solvent for the polymer and the diluent contains for viscosity lowering, determined at a temperature of about 90 ° C to about 135 ° C, lower than the viscosity of the mixture containing the same amount of polymer and crystalline solvent without any diluent being present, the viscosity at the same temperature is determined. in the use of heterogeneous suspensions with a low viscosity containing the PVA described in U.S. Patent 3,654,247, the "diluent of the application of the polymer and the crystalline solvent acts to reduce the viscosity ¹¹ as a carrier to facilitate in or on the ce llulose-containing 'substrate. In contrast to the limited number of compounds useful as crystalline solvents for the polymer, a relatively wide range of materials can be used as viscosity lowering diluents. A major requirement is that such diluents be relatively unreactive in the mixtures. A further requirement is that the diluent be completely miscible with the mixture, although it need not be a solvent for the binder component itself. As a diluent for lowering the viscosity, water, liquid polyhydric, ie containing several hydroxyl groups can be used.

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de Compounds such as glycols with 2 to 9 carbon atoms, glycol ethers (in which the acyl group contains 2 to 4 carbon atoms), low molecular weight (up to a molecular weight of 1000) polyalkylene oxides and their alkyl ethers (where the alkyl group contains 1 to 4 carbon atoms), polyalkylene oxide esters' (where the acyl group contains 2 to 4 carbon atoms), liquid alkyl-substituted ureas (with up to 9 carbon atoms in the Alley l group), such as tetramethylurea and tetraethylurea, liquid aliphatic amides containing up to 6 carbon atoms, such as formamide and Use dimethyl sulfoxide. In this context, the term “liquid” means that the compound mentioned is in a liquid state ^{at 20 ° C.} Some solid diols also show a viscosity lowering effect. Water, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, dimethylsulfα y ± d and formamide are preferred diluents for reducing the viscosity.

These diluents should be used in adhesive compositions according to the invention or compositions in an amount of about 5 to 80 wt.%.

At concentrations of the diluent for reducing the viscosity below about 5 / S the melt is very gaseous, due to the development of ammonia during the conversion of polyvinyl alcohol and urea. At concentrations of the diluent to lower the viscosity above about 8055, the adhesives develop the green strength or fiber tear properties not as fast as desired.

The concentration of diluent to lower the viscosity has a significant influence on the properties and characteristics of the various types of adhesive mixtures, which can be produced according to the invention. With homogeneous

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Melting activates a concentration of diluent and a reduction in viscosity below 3%, the formation of ammonia, which is caused by the reaction of polyvinyl alcohol and urea. If the concentration of diluent used to lower the viscosity is more than a quarter or a half , the melted, homogeneous adhesive mixture does not develop the green strength or fiber tear properties quickly enough.

Melted, homogeneous mixtures that contain up to about 15? S water as a diluent to reduce viscosity require handling temperatures of 115 to 135 ° C and must be stored in tightly closed containers to prevent water loss. When about 15 to 30 ^ water are available, v / ith the melting point of the mixture is lowered, and a handling at about 90 to 110 ⁰ C is possible, provided that one prevents loss of water by evaporation v / ill. In melting, the longer included as etv / a 30% water, handling about 100 ⁰ C is easier because they have improved stability and lower viscosities, but the loss of water from these mixtures should still · kept to a minimum v / ground. Homogeneous mixtures containing more than about 30% water generally do not develop green strength and fiber tear-bond and water resistance properties. This also applies to homogeneous mixtures with a low water content.

In the inventive viscous, heterogeneous mixtures processing or handling temperatures can be obtained 40 to 80 ⁰ C of etv / a. These application temperatures are desirable since the loss of diluent to lower the viscosity can be further reduced. With this type of adhesive composition, diluent concentrations below about $ 20 will result in too high a viscosity. On the other hand, concentrations of diluent for viscosity lowering result in over about 40 μs of compositions with too

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low viscosity, and such compositions do not exhibit sufficient tack to be used as adhesives to be able to.

In the adhesive compositions of the invention stable type of suspension with low viscosity Diluent concentrations from about 30 to about 80% vary. Below a 30% concentration of diluent To reduce the viscosity, there is not enough diluent (e.g. V / water) available for complete dissolution the crystalline solvent or for satisfactory dispersion of the polymeric binder, d. H. Polyvinyl alcohol. At concentrations above about 80ja water is the subsequently heat-activated adhesive to flow and adheres on contact with the cellulose-containing substrate, to which it is applied is not sufficient.

The homogeneous, molten adhesive systems according to the invention can be produced by various processes, as explained below. You can use a dry mixture, for example from 28 parts of Elvanol ' ^R ' 90-50 (polyvinyl alcohol, degree of hydrolysis 99.0 to 99.8 ^, a viscosity of 12 to

14 cP. at 20 ° C as a 4-6 aqueous solution available from EI du Pont de Nemours and Company) and 72 parts of urea, pulverized so that it passes through a 0.42 mm (40 mesh) sieve, with stirring, to 35 parts of water , which is heated to 70 to 85 ° C. The addition takes place at a sufficiently slow rate that a minimum temperature of 70 ° C. is maintained in the mixture. It takes about 1/4 to 1/2 hour. The mixture is at 85 to 90 ⁰ C during further

Hold for 15 minutes so that a high degree of homogeneity is achieved. The resulting product is stable. After storage for 2 days at the application temperature of 90 to 95 ° C no adverse effects are observed on the mixture provided that it is stored in a closed container

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occurs so that loss of Y / ater is prevented. A similar process can be used to produce a molten, homogeneous adhesive system in which the diluent for viscosity reduction is a glycol (e.g. propylene glycol) instead of Nasser, except that a mixing temperature of 120 to 130 ⁰ C is used and the product is 110 is used up to 115 ° C. In the production of the molten, homogeneous adhesive systems according to the invention, the polymer binder or binders and the crystalline solvent component are added in portions to the melt so that the formation of mixtures with excessive intermediate viscosities is avoided.

The molten, homogeneous adhesives of the invention (eg based on PVA, urea and water) give the unexpected and desirable advantage of obtaining bonds which are very water-resistant. The preferred method for achieving this goal is "setting by VJärae". For example, after brief heating, corrugated cardboard produced using the adhesives according to the invention shows a significantly improved water resistance at ambient temperature, determined with the shear test This test consists in placing a 2 15 cm piece of cardboard vertically so that the grooves run horizontally in water at ambient temperature under 350 g of dead shear stress (correcting for buoyancy) Applying this shear force to only five trough, sections (the test zone), the cardboard on the front side is cut in the direction of the corrugation immediately above the test zone Wear a load of 350 g for at least 24 hours liver is produced without "heat setting" fails in 1/2 to 2 minutes. Through a suitable "heat setting" the best

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More than 85% of the specimens that were examined passed the test. A number of methods for carrying out the "semi-binding" of the bonded substrates have been developed. One method is to apply V / arm directly to the bond site through the face of the face sheet, as illustrated in Example 8. In another method, the sample is contacted with the surface of an infrared lamp in contact until the temperature in the Leimzeile 100 ⁰ C (212 ° F). Under these conditions, 1PO? S of the samples pass the test. Another method uses radio frequency energy. Using a "radio frequency heater" (FI-IC Model 67, sold by WT Larose and Associates, Inc. of Cohoes, NY) and operating at 40 megacycles under the following conditions, bonds are formed that support the test exist without exception.

Voltage (volts) exposure time (see)

100 25

125 10

140 5

150 5

175 .2

200 <2

It has also been found that the incorporation of a variety of wetting agents increases the water resistance of the with the adhesives used as hot melt adhesives according to the invention, produced connections or bonds is improved. In the absence of such wetting agents or if post-heat treatment is omitted, the bond occasionally fails the dead load shear test at the glue (i.e. between the binding and the paper). The incorporation of a suitable wetting agent facilitates the moisture penetration of the substrate by the adhesive. As a result, the cohesive force, the high order

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tion is limited even under water immersion conditions, and the phenomenon that the bonds exist upon immersion in water increases significantly, that is, upon immersion in water, there are far more bonds. Wetting agents suitable for this purpose include sodium lauryl sulfate, polyethylene oxide-alkylphenol adducts and their phosphate esters (e.g. "Triton" C-305 and "Triton" QS-9, available from Rohm & Haas), quaternary ammonium salts, various inorganic salts, such as alkali phosphates and sodium nitrilotriacetate. These materials are incorporated in amounts of about 1 to 5 percent based on the weight of the adhesive. It has been found that the use of a wetting agent can reduce the amount of post heat treatment required to produce bonds that pass the ambient water resistance test when the adhesive mixture is applied as a melt.

The use of a latent curing agent is suggested if resistance to boiling water is to be obtained. Such a hardening system can be made from titanium citrate and use glycolic or citric acid. About $ 2 o Titanium citrate and about 2 to 4 $ 4 of either glycolic or citric acid (based on the weight of the adhesive) are suitable. The acid reduces the pH of the mixture to 3.5 to 4.5, where it shows its normal melt flow behavior. The hardening can be done either by treating the bonded substrates with Ammonia (aqueous or gaseous) or by heating to a temperature above 160 ° C for several minutes, so that sufficient ammonia is evolved from the adhesive to cause a curing reaction.

Another cure system developed for the molten adhesives of the present invention in which the liquid co-solvent V / ater is is a hardening system on the Based on resorcinol and formaldehyde. The preferred hardening

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agent consists of 2 parts resorcinol and 2 parts urea and 3 parts 37% formalin, which by heating 15 minutes at 90 to 95 ° C to be converted into a resol. This resol results in when it is in the adhesive in levels of 2 to 10/0 (based on the weight of the adhesive) incorporated bindings that, after aging, have adequate water resistance for 14 to 21 days under ambient conditions develop so that they pass the dead load shear test.

Resol compositions based on resorcinol, Urea and formalin can be a composition is range from 1: 1: 1 to 1: 1: 3 resorcinol / urinary toxin / formalin and they can be used over a concentration range of about 1 to 20%, expressed as the weight of the adhesive. In addition to aging at ambient temperature to a semi-dry state for 14 "to 21 days, these can Mixtures hardened by heating for several minutes at 120 to 150 ° C v / ground.

The polyvinyl alcohol adhesive mixtures according to the invention, the Urea contained as a crystallizable PVA solvent are not combustible, incapable of creating a flame in the vertical maintainable, relatively non-charring with little or no afterglow. The ilengen used these materials reduce the combustibility of the cellulose-containing ones Maters ax they are glued to, not essential if they are not used together with known flame retardants, such as ammonium sulfamate, used v / ground.

Viscous, heterogeneous adhesive systems which can be used in a temperature range of 40 to 8O ⁰ C used v / ground are made as follows. 50 parts of urea are added to 70 parts of water and the solution is heated to 70.degree. 20 parts Elvanol '' 90-50 v / earth while stirring with evenly

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added speed to the urea solution, the temperature being kept at 70 ° C. The mixing is ergeführt w ext is until the Geniisch at 70 ⁰ C uniform. Then 93 parts of finely divided calcium carbonate are added. Mixing is continued until the mixing temperature is 70 ° C. The resulting heterogeneous mixture is stable and can be relocated for several days in a sealed container at 40 to 80 ° C without any loss of adhesive properties.

Adhesive systems of the heterogeneous, stable suspension type with low viscosity, which is reactivated by heat to produce water-resistant bonds or bonds v / ground can be made as follows. 40 parts of urea are added to 40 parts of water at 25.degree. A clear solution is obtained. 20 parts Elvanol 'ν 90-50, treated according to the method of US Pat. No. 3,654,247 are dispersed in the urea solution. 1 / 1O ^ GuargUTPmi ("Jaguar" A40-F available from Stein, Hall and Company, Inc.) is then dissolved in the aqueous phase. A suspension is obtained which is stable for several days at room temperature remain.

The following examples illustrate the invention. The percentages and parts are expressed by weight unless otherwise specified. Examples 1 to 85 illustrate the molten, homogeneous mixtures according to the invention.

example 1

A mixture of 400 g urea and 400 g water is placed in a Brabender mixer and stirred. As soon as most of the urea has dissolved, 200 g of polyvinyl alcohol ("Elvanol" 90-50, degree of hydrolysis 99.0 to 99, S? S, with a viscosity of 12 to 14 cP. At 20 ⁰ C as 4 # ige aqueous solution; available from EI du Pont de Nemours and Comp.)

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added as soon as possible to form a thin slurry. One heats up. As the temperature of the solution increases, a progression of thickening of the mixture can be observed. Its viscosity reaches a maximum at 40 to 50 ⁰ C. When v / Eiteren heating dilutes the mixture becomes clear and is at a temperature of 80 to 90 ⁰ C very fluid (viscosity about 2000 cP.); this process takes about 15 to 20 minutes.The mixture is placed in a polyethylene bag and cooled to below 5 ° C to induce gel formation. The gelled product is crushed into chips and stored in a moisture-proof container to prevent water loss.

At Soiel 2

Using a Cowles® dissolver, 1500 g urea and 200 g water are heated to 125-135 ° C with stirring. Add 500 g of polyvinyl alcohol ("Elvanol" 90-50) to the melted Hasse as quickly as possible. Man stir until mixture is completely melted and cleared. At this point it will be on a "Teflon" sheet poured where it crystallizes immediately. The resulting plate is broken open and pulverized. The finely divided Product is either used as is or is compression molded into cartridges for use in hot melt guns. The product is stored in a moisture-proof container.

Beisr> iel3

A 12.7 to 25.4 / U (0.5-1 ', 0 mil) thick film of the adhesive composition of Example 2 is formed between ⁿ Mylar "sheets by pressing in a heated Pasadena press. The film is made Frozen, one of the "Mylar" sheets is peeled off and a piece of Kraft paper is inserted in. Mild heating (90 to 95 ° C) and low pressure (1.05 to

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AD 4754A **

1.41 atm = 10-20 psig) are used in the Pasadena press to bond the Kraft paper and one side of the adhesive film. The structure is frozen again, the second "Mylar" sheet is lifted off and a second piece of kraft paper is placed on top. The second sheet of kraft paper is then bonded in a Sentinel heat packer using a 1/2 second treatment time, a pressure of 4.92 atmospheres (70 psig), and a bar temperature of 135-175 ° C. The laminate exhibits strong fiber tear bonds after soaking in ambient water; however, rapid delamination takes place in water that is ^{heated to about 70 ° C.}

Example 4

A 15 »2 cm (6") roll coater that comes with a heated and jacketed pan is used to apply the molten glue used on the application roller. This device is equipped with double Kraft paper feed rollers, see above that a laminated structure can be made. The experiment is carried out by first looking at the adhesive composition of Example 1 in a separate jacketed reservoir and heated to a Maintains temperature of about 85 to 95 ° C. After the paper starts to feed at a speed of 6.1 m (20 ft.) / Min occurs, the melted adhesive is pumped into the heated application pan at the rate at which it was applied the paper is applied. In this way, a structure in which two sheets of Kraft paper of 25.4 to 50.8 / u (1-2 mil) adhesive (Trocljsnbasis) are glued, produced, The adhesive can be applied smoothly without any gaps or gaps. There is also no unwanted glue build-up on the applicator roller as the experiment progresses. After completion of the experiment, the pre-device can be wash easily by hot water. The glued

- 23 - ■

809842/0087

AD 4754a

Structure shows excellent resistance to high humidity and water at ambient temperature. she can easily be converted into a pulp in hot water

v / earth.

example 5

In this example, a 63.5 cm (25 ") device for manufacturing corrugated board (corrugator), wherein the application rollers are heated to 85 ⁰ C. Approximately 0.454 kg (1 Ib) of the mixture from Example 1 are melted and the A single lane, corrugated structure is passed over the roller at a speed of about 30.5 m (100 ft.) / Min, so that the The second web is then laid down and the resulting structure is passed through several pressure rollers before moving to about 3.1 to 3.6 m (10-12 ft.) Along the Line or line is cut. The adhesive shows excellent rheology on the device as long as its water content is retained. A suitable "green strength" has accumulated in the structure when it is at the collecting station is sufficient, and after the structure has been allowed to age for 3 to 5 minutes, a fiber tear bond is observed. The corrugated structure shows little or no "ribbing" (which is in direct contrast to structures made with known cardboard adhesives). Cleaning of the device at the end of the experiment is relatively simple due to the ease with which the glue build-up can be removed from the application roller and the glue is also readily soluble in hot water. An examination of the resulting, corrugated structure shows the adhesive's excellent behavior. The dry pin adhesion (corrugated grooves to the upper web binding) is

- 24 8 0 9842/0087

30 2 7 T R 4 3 A

AD 4754A

better than strength [e.g. 38.6 to 45.4 kg (85-100 lbs) versus 22.7 to 31.8 kg (50-70 lbs)] at about 1/2 to 2/3 of the load [e.g. 0 .68 kg (1.5 lbs) versus 0.91 to 1.36 kg (2.0-3.0 lbs) / 9.3 m ² (1000 ft. ² ) cardboard]. The paperboard bonded with the adhesive of this example shows excellent water resistance at ambient temperature in the ply peel test. Fiber tear bonds are still observed after 10 active immersion. In contrast, structures bonded with starch delaminate after immersion for 1 to 2 minutes.The structure bonded with polyvinyl alcohol-urea can quickly be slurried again in hot water or processed into a paste.

Example 6

A 23/68/9 polyvinyl alcohol ("Elvanol" 90-50) / urea / v / water mixture is compression molded into 7/8 "x1 1/2" (2.22 cm by 3.8 cm) cylinders and inserted into known hot melt guns used. The material can be handled very well within a temperature range of 130 to 150 C. It adheres very quickly to paperboard and forms fiber tear bonds within 1 to 3 seconds. When cooling to un
the bonds 100% fiber tear bonds.

Fiber tear bonds. When cooling to below 100 to 110 ⁰ C are

Example 7

The mixture from Example 2 is placed in powdered form in an LTI "Dynapply" 45D carton or box sealing unit which is equipped with an LTI G type 4 nozzle head. The material is melted at a temperature of 129-149 ° C (265-30O ⁰ F) and then applied by pumping it through the nozzle assembly. The glue is quick to apply to Kraft paper and its adhesion and tack are excellent The molten adhesive is found to create fiber tear bonds upon contact with the kraft paper

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AD 4754A

forms. The line of glue seems to have an open time of 1 to 3 seconds possess and form fiber tear bonds in the laminate almost immediately when the sheeting is in contact with the sheet Adhesive-containing web is brought - These bonds show very good water resistance at ambient temperature, they delain in water, however, at 73.9 ° C (165 ° F) or higher.

Example 8

A 2 cm 12 cm piece of corrugated cardboard, glued with an 18/47/35 "Elvanol" 90-50 / urea / water mixture and air-dried for several days, is used in the dead load shear test for water resistance. This paperboard member 30 see at 149 ° C (300 ⁰ F) on a Pasadena press under low pressure heated and then subjected to the determination of the resistance to water at ambient temperature, the dead load shear test. Under the test conditions, the sample can withstand immersion for more than 4 hours. The results obtained by performing the heat set under a variety of conditions are summarized in Table I.

Table I.

Heat setting Frequency of passing

Duration temperature ^ 1; CC F) longer than 24 h (2) (%)

■ '- "■ 0

65 75 100 70 65 35 70

- 26 -

2 H 93.3 (200) 15th min 93.3 (200) 1 min 149 (300) 30th lake 160 (320) 1 sec 249 (480) 1/2 sec 299 (570) 1/2 sec 360 (680)

809842/0087

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(1) Temperature of the surface against which the outside of the corrugated board was pressed during the specified time.

(2) Based on 6 to 8 samples with applied amounts of adhesive in the range from 0.34 to 1.13 kg / 9.5 m (0.75 to 2.5 lb / 1000 sq.ft.) corrugated cardboard.

Examples 9 to 24

Various mixtures containing glycols and glycol ethers are also tested. Both the melting properties and the adhesiveness of these mixtures were investigated. The test results are summarized in Table II. It can be seen that, with the exception of glycerol, which results in a very unstable melt, all of the other additives investigated result in mixtures which, overall, have good to excellent bonding properties. The only disadvantage that was found during testing was the poor water resistance of the resulting bonds in most cases. It is not believed that this Kachteil the usability of the mixtures according to the invention, for example the use in bonding cartons and bookbinding adhesives, significantly limits.

- 27 809842/0087

Table II

E.g. mixture no. composition (weight ratio) ■ "TElvanol" 9O-5o7 urea / "X"

Properties of regular kraft paper

»X» dry fast fusion bond adhesion (i) stabili- (see) strength (2)

V / water

resistant-

ability (3)

O
CO
OO

11 12 13 14 15 16 17 18 19 20 21 22

19/56/25 19/56/25 19/56/25 19/56/25 18/55/27 18/55/27 18/55/27 20/59/21 25/50/25 25/50/25 25/50/25 25/50/25 20/60/20 20/60/20 20/60/20 20/60/20

Pr opy 1 englyko ethylene glycol Trlethylene glycol Glycerin Cellosolve Carbitol Butylcellosolve Carbitol - = - acetate Carbitol '' Cellosolve Butylcellosolve Carbitol Acetate Ethylene glycol propylene glycol diethylene glycol Triethylene glycol fiber tear binder.

1-2 1-2

2-3

not tested fiber tear binding. 2-3 2-3 2-3

»2-3

2-3

"i 2-3

2-4

κ 2-4

»1-2

"1-2

ii 2-3

κ 2-3

excellent excellent. Well "

good moderate very bad not assessed

good good good good good good moderate bad good

excellent good good

very bad

Il Il Il Il Il

excellent

Il It

bad

bad is> —j

AD4754A ³ ^ 27 1 5A3A

Notes to Table II:

(1) The time required for the bond to set by crystallization.

(2) Excellent = less or no changes after 24 hours at 95 °; good = slight increase in viscosity at 95 ° C .; moderate = moderate gas development accompanied by a moderate change in viscosity; bad = phase separation; very bad = too unstable for testing.

(3) Water resistance for 2.54 cm overlapping bonds after immersion at 25 ° C for 24 hours; excellent = 10056 fiber tear bond; good = some fibers tear; moderate = no fiber tear and no delamination; bad = partial delamination; very bad = quick, complete delamination.

Examples 25 to 61

In the following Table III are the compositions and properties of the various molten homogeneous Mixtures according to the invention and some comparison mixtures summarized.

Notes to Table III:

(1) Viscosity designations: moderate = 2000-5000 cP; moderately high = 5000-7500 cP; high = 7500-10,000 cps; very high = over 10,000 cP.

(2) Melt stability designations: excellent = no or only slight gas formation is observed, the viscosity remains constant after several hours of heating; good = moderate gas formation, slow increase in viscosity when heated; moderate = moderate gas formation and remarkable changes in viscosity after heating for 2 hours; bad = considerable gas formation and the development of poor application properties after heating for one hour.

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(3) The time required for a fiber tear bond to be achieved.

(4) Tested with the T-peel (T-peel test).

(5) The "water resistance" is determined after 24 hours of immersion in water of a two-layer Kraft laminate at ambient temperature and rated as follows: excellent = the bond still shows a 10050 fiber tear bond; good = the bond still shows more than 50% fiber tear bond; moderate = only slight ones are observed Fiber tear bond; poor = no fiber tear bond observed, but the sample does not delaminate; very poor = 100 $ delamination occurs.

(6) PG = propylene glycol.

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809842/0087

Table III solvent Diluent f.d. in melted condition ti io (75) - • - PG Other kind (1) heterogeneous Enamel I. excellent Bonding properties > 4 Dry water ui 2-5 100 excellent E.g. for PVA Viscosity reduction Viscose (75) - (10) 23 (6) moderate stabili Well compared to Kraft paper fi bind. (4) persist- £ 3-6 100 η No. Mixture composition (weight ratio) Mixture properties Urinary Others water (50) - 23 heterogeneous strength (2) bad Snow. (% Fiber consistency 1-2 100 " »Elva- crystal.Lö- material H - moderate excellent les teardrop- (5) 1-2 100 " nol " 20th moderate «. 11 Well Be liable dunp;) 90-50 (75) - 10 _ « - U (4) 100 excellent - Thiourea (60) - - ammonium formate (66) - very high - » [lake) 100 » H - ι » 34 high 1-3 100 « 25th H 48 acetamide Glycerine very high 1-3 <10 bad 26th 20th - biuret 48 (34) 1-3 <10 » α> 27 20th ■ mm " • 60 > 4 P ²⁸ 25th 56 12th > 4 not tried) ⁽ α> 29 17th - <10 bad NJ 17th - bad (sticking very bad (sticking not vers.) Sf 30 10 Well excellent 3ί 31 25th 20th Il OO
^ 32 22nd 25th Il 33 25th It 34 19th 35 19th 36 20 ' 19th

Table III (continued)

E.g. mixture composition (weight ratio) mixture properties No. "Elva- Kristall.Lö- Verdünnungsm.f.d. In molten.State

Solvent, viscous butter mixture.

90-50

solvent for PVA

water

Urine- other substance

PG (6) Others

Viscosity (i)

Melt stable! -
• kind (2)

Bonding properties. to Kraft paper ^ 'Schnei- dry- water-ui les bind. (4) resistant-> adhesion (% fiber-tightness (4) tear-binding- (5) (see)

O
CO
OO

37

38
39

40
41

S vjj 42

ι 43

44
45
46

: 47
'48

19th
20th

20th
19th

25 "

25th
18th

60

56 60

19 48

60 56 50

55 50 55 50

23

- ethylene

glycol (20) moderate

» (25) it

- diethylene "
glycol (20)

Well

Il

excellent

Well

Il
Il

- triethylene "
glycol (10)

κ (20) "
μ (25) ι.

- Cellosolve (25) moderate

high

"(27) moderate»

- Carbitol (25) moderately high "'·.

»(27) moderate"

- Butylcello - moderately high moderately
solve (25)

(27) moderately good.

1-2 1-2 2-3

3-6

2-3 2-3 2-3

2-3 2-3 2-3

2-4

2-3

100 100 100 bad

excellent,

Il

100 moderately good

100 moderately i- ¹ 100 moderately good

100 very

bad

100 "

100 "

100 "

100 "

100 "-J

'Jl

E.g.
No.

• "" Table III '(' continued) "."

Mixture composition (weight ratio) Mixture properties "Elva- Kristall.Lö- VerdUnnungsm.fd in melted.Stand solvent viscostifcätsyermind ..
for PVA

nol »90-50

water

Urine- other substance

Other

VISIBILITY (1)

Melt Stability (2)

Bonding properties compared to Kraft paper

- V /

, right ^

'Snow-dry-V / ater-vji

les bind. (4) persistent

Stick (% Fdikit (4) (sec)

(% Fiber strength tear-bond (5) bond)

49

50
51

53
54
ι 55

56

57

58

20th

25 20

25th

33 17 14 20

25 33

59

50 40

25th

33 50

43 40

25 33 Carbitol-. moderate
acetate (2i)

(25)

II

■ dimethylformamide (40) "

»(50)»

Well

bad
excellent

ti

"(33) very high moderate

"(33) moderately high good

"(43) moderately good

- N-methyl- "marked,
pyrrolidone
(40)

"(50) ■« "

"(33) very high moderate

2-3 2-4

2-5

> 60 2-5 2-5 2-4

1-3 3-6

100

100

very bad

100

partially

Fiber tear

binding

bad

Il

<10 very bad 100 bad 100 » 100 "

100 100

It ti

E.g., no.

Table III (continued)

Mixture composition '(weight ratio) "Elva- Kristall.Lö- VerdUnnungsm.f.d. Solvent viscosity low.

90-50 for Fy_A Waiser Pcf

(6)

Urine- Other substance mixture properties
in melted condition

Viscous! - Melt

Different kind (1) Stability (2)

Bonding properties compared to kraft paper

"Schnei- Trocken- W

• The binding (4) be3tain-> Adhesion (% fiber strength (4) tear-binding- (5) (see) dun /?)

59 60 61

60

60

- Pentaerythritol60) -

- Dimethyl sulfate oxide (20)

- formamide (20) "

- Dipropylene "glycol" (20)

excellent,

Well

4-7

partly moderate

1-3 100 moderate Well 1-3 100 moderate

rs)

cn

CO

271

AD 4754A ^{L I.}

Examples 62 to 70

As illustrated in these examples, adhesives belonging to the molten, homogeneous blend type based on "Elvanol" 90-50 PVA and / or "EVAL" 80 E / VOH copolymer have excellent water resistance.

A mixture of "Elvanol» 90-50 and / or "EVAL" 80 (35/67 wt. % E / VOH copolymer, sold by Kurashiki), urea and propylene glycol is stirred for about 1/4 to 1/2 hour heated at 135 ° C "until a homogeneous melt is obtained. The latter is then applied as a thin coating on one side of a 2x3 cm portion of a face sheet material. A bond is produced by placing a second part on this cover and cooling the resulting overlapping cover to room temperature. Finally, the bonded structure in water is dipped, for 24 h at Uagebungstemperatur stored and then by hand to test the Delaiainierungs- "pulled apart resistance as well as for testing binding, the failure of the adhesive during the fiber tear. If we examine the properties of the composition ¹¹ EVAL" 80 alone or together with "Elvanol" 90-50, it can be seen from Table IV that the presence of even a relatively small amount of "EVAL" 80 (for example 3 to h%) provides a high degree of delamination resistance in the corresponding adhesives - "exercises are obtained even with difficult to" humidify, for example when using resin-sized products. Fibrous tear bonds are noted when the "EVAL" 80 levels in the blend reach about $ 135. ·

Mixtures containing "EVAL" 80 cannot be completely reprocessed to a wide range and are therefore suitable for the Production of water-resistant corrugated cardboard suitable where reprocessability into a pulp is not required is.

- 35 809842/0087

Bondings made between parts of the same three types of top sheets with a 20/60/20 "Elvanol" 90-50 / urea / propylene glycol composition. getting produced, delaminate for about 5 to 15 times on this attempt.

Examples 71 to 85

Melted homogeneous blend type adhesives based on "Elvanol T-25 and 71-30 PVA are compared to the same type of" Elvanol "95-50 PVA based adhesives in these examples." Elvanol "T-25 PVA has a degree of hydrolysis of at least about 99? 6, a viscosity as a 4% aqueous solution of 25 to 31 cps. at 20 ⁰ C and is available from EI du Pont de Nemours and Company. "Elvanol" 71-30 PVA has a degree of hydrolysis 99.0 to 99 _°} Q / _t o a viscosity as h% xge aqueous solution of 28 to 32 cP. and is available from EI du Pont de Nemours and Company. The Gemischzusamrnensetzungen and their properties are summarized in Table V.

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809842/00 87

Table IV

E.g.
No.

Mixture composition (weight ratio

"Elvanol" 90-50

"EVAU ^ urea

viscosity

ropylene glycol conditions
(RVT-SC4)

RPM

Temp.

Through heating viscosity to £ j

cutting cycle would take / h uj,

borrowed (h) cP "! 5S j>

(cP.)

62
63
64
65
66
67

ι ⁶⁸

uj 69

T 70

0 0 0 0 0 10

15 18 16

20 16. 13 "10

5 10

5 3 4

60 64 67 70

75 60

60 59 60

20 20 20 20 20 20 20 20 20 5-2.5 130 28 333

1333

50 130 1 992 5.25 62

100 130 575 4.25 24

100 130 215 4.5 9

(estimated at <100 cP. at 130 ⁰ C)

130

8 021

545

4.7 3.1 4.1 4.4

6.8

No. Used
Oberbahn (i)

Table IV (continued)

dor Ubor] nppond on Vorlobu n ron after 24ntünrli / rcm Elntou ch on

"""binding

Delarainierungsbündigkeit

estimated

AnzafiX ~ cl. Tested Bonding

62

63

6 /,

65

Ä 66

67
68

69
70

force

force

Weyerpak

Resin-sized

force

Weyerpak

Resin-sized

force

Weyerpak

Resin-sized

force

Weyerpak

Resin-sized

force
force

force

Weyerpak

Resin-sized

force

Weyerpak

Resin-sized

very high

very high 3 very high very high

high very high very high

high-very high

high

high

moderate

moderate-moderate high moderate

moderately-moderately high

high-very high no

high-very high high-very high high-ear high

very high very high very high none

very strong

weak-moderate

strong

moderately strong

moderate

awake-moderately

none-weak

none-very weak

no

none-very weak

no
no
koine

none-weak

none-weak
no

none-weak
none-weak
no

no

none-weak
no
no

100

100 100 100

60-80 0-30 0-25

0-10

0-10

0 0 0

0-25

0-25 0

0-25

0-25

0-25 0 0

4 4 4

4 4 4

4 4 4

4 4 4

4 4 2

4 2 1 1

(1) Upper web used: 90 ^ regular Kraft paper; 42 ^ Weyerpak. commercially available, ^

water-resistant Weyerhaeuser product; 42 ^ Resin Sized or treated, water-resistant upper sheet material with low porosity, test product from Weyerhaeuser

Table V

E.g. mixture composition (weight ratio) ... mixture properties

No. "Elva-" Elva- "Elva- urinary propylene shafts in

nol "nol ^H nol" substance glycol melted

90-50 T-25 71-30 condition

Viscose "Schraelztät (1) stabil-

Bonding properties compared to Kraft paper
Schnei- Dry- Wasserles Haf- binding (4) permanent (# Fibrous- (5) (see) (3) tear-binding

71 - 17: - 67 17th very high high Well 1-2 100 Well Well Well 72 8.5 8.5 - 67 17th high It from ge ζ. 1-2 100 Well well £ excellent. IF 73 - 67 17th very high It Well 1-2 100 excellent « Well 11 -O O
(O 74 8.5 - 8.5 67 17th moderate ti excellent 1-2 100 Il Well OO
4>. 75 . - 19th - 56 25th very Il It 2-4 100 Well 76 - 20th - 60 20th ti It It 1-3 100 Well O 1 ₇₇ 9.5 9.5 - 56 25th Il Il ti 2-4 100 excellent O
CO from 78 10 10 - 60 20th Il ti Il 1-3 100 Il -4 ¹ 79 10.5 10.5 - 64 15th Il Il Well 1-2 100 80 9.5 9.5 56 25th Il Il Well 3-5 100 81 10 - 10 60 20th Il ti Well 1-3 100 82 10.5 mm 10.5 64 15th Il Well 1-2 100 83 - - 19th 56 25th ti Well 2-4 100 84 - 20th 60 20th Il Well 1-3 100 85 - 21 64 15th Il Well 1-2 100

AD 4754A

Comments on Table V:

(1) Viscosity designations: moderate = 2000 to 5000 cP; moderately high = 5000 to 75 ⁰ O cP; high = 7500 to 10,000 cps; very high = over 10,000 cP.

(2) Designations for the peeling stability: excellent = if little or no gas formation is observed and the viscosity remains constant after heating for several hours; good = little gas formation, slow increase in viscosity when heated; moderate = moderate gas formation and noticeable change in viscosity after heating for 2 hours; bad = considerable Gas formation and poor application properties after heating for one hour.

(3) The requirements for creating a fiber tear bond: lent time. (4) Tested with the T-peel.

(5) The water resistance is determined after immersing a two-layer kraft laminate in water for 24 hours at ambient temperature determined and rated as follows: excellent = the bond still shows a 100% fiber tear bond; good = the bond still shows more than 50% fiber tear bond; moderate = only a slight fiber tear bond is observed; bad = no fiber tear is observed, but the Sample does not delaminate; very bad = 1005 & delamination occurs.

In Examples 86 to 89, the viscous, heterogeneous mixtures explained.

Example 86

60 grams of urea and 53 grams of water are placed in a 0.25 liter stainless steel beaker fitted with an electric heating block

is heated and equipped with an air driven stirrer is. After the temperature of the solution has reached 75 ° C, 20 g of polyvinyl alcohol (Elvanol '' 90-50) with uniform

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AD4754A. ^ 2 7 1 5 4 3 A

Rate added; stirring is continued until a clear solution is obtained. The viscosity of this solution is 850 cP. at 70 ^° C. A comparable composition is produced without urea and is a solid gel ^{at 70 ° C.} 44 g calcium carbonate with pigment quality v / earth stirred into the solution; a heterogeneous mixture is obtained which contains a total of 7054 solids. The viscosity of the mixture is 1800 cP. at 70 ° C; 2800 cP. at 60 ° C and 7500 cP. at 50 ⁰ C, measured with a Brookfield Viscometer, RVT moduli, spindle no. 2 at 5 U / min.

Example 87

A thin coat (about 25.4 to 50.8 / u = 1-2 mils) of the adhesive Mixture of Example 86 is applied to the tip (0.3 cm deep) a 2.5 x 5.0 cm Kraft paper coupon applied. A bond is established by placing a second coupon on it this coating lays and the bonded connection (0.8 cm) is allowed to set at room temperature. The glued structure is immersed in water at a load of 350 g (corrected for buoyancy) and stored for 24 h at ambient temperature. After this exposure, a fiber tear bond is observed at ambient temperature, but the adhesive pull can in water at 70 ° C can be processed into a paste again.

Example 88

81 g of έ, -caprolactam and 91 g of water are placed in a 0.25 liter stainless steel beaker and, as described in Example 86, heated. After the solution has reached 75 ° C., 30 g of polyvinyl alcohol (Elvanol ^ ^R '90-50) are added and the mixture is stirred until a clear solution is obtained. The viscosity of this solution at 70 ° C is 276 cP. A comparable composition that is produced without <£ -caprolactam is a solid gel at 70 ° C. 104 g calcium carbonate pigment quality are stirred into this solution; you get a sticky,

- 41 -

809842/0087

AD 4754A

heterogeneous mixture containing a total of 7055 solids. The Brookfield viscosity of this mixture is 1200 cP. at 55 ° C.

Example 89

A bonded structure is made with the adhesive mixture from example 88 made according to the procedure of Example 87, except that the bonded joints were made under a Infrared heating lamp can be dried for 5 min at a surface temperature of 100 ° C. The bonded structure is in ¥ water, as described in Example 87, immersed. After 24 hours, a fiber tear bond is observed at ambient temperature, but the adhesive coating can be made into a slurry again in water at 70 ° C.

In Examples 90 to 93, the invention is stable Low viscosity suspension explained.

Examples 90 "to 95

Adhesive suspensions based on PVA, which are produced by post-heating are made by dissolving urea in water, adding guar gum as a suspending agent, then dispersed in the solution a heat-treated polyvinyl alcohol prepared in accordance with US Pat. No. 3,654,247. The adhesive compositions produced by this process are summarized in Table VI.

A thin coat of each of those described in Table VI Suspensions are placed on top (0.3 cm deep) of a 2.5 χ 5.0 cm Kraft paper coupon and set aside so that he can dry. A bond is produced by drying a second, uncoated coupon on top of this Coating and the overlapping parts in

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AD 4754A

a sentinel Heizabdichtungsvorrichtung 7 sec "at a 0.98 kg / cm (14 psi) clamping pressure heated at a bar temperature of 190 ⁰ C. The resulting, bonded structures v / ground in water, v / ie described in Example 87 is immersed. after 24 hours of exposure under these conditions is observed a fiber tearing bond, but the adhesive coating may be re-processed to a pulp in water at 70 ° C.

composition urea Table VI 0.20 Solids ^) E.g. PVA 20th 0.06 20th No. 10 40 0.30 70 90 20th 70 of the mixture (weight ratio) 0.10 20th 91 10 60 Water "Jaguar" A · 40-F 60 92 10 120 93 26th 320 46

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809842/0087

Claims (16)

Claims 1. polyvinyl alcohol adhesive composition, characterized in that that it essentially contains or consists of: about 2 to 35 wt. 96 of a polymer from the group Poly vanyJLaJUcpjigl and ethylene / vinyl alcohol copolymers containing at least 50 mol / y vinyl alcohol, about 10 to 80 wt.% of at least one solvent for the polymer, which solvent is crystalline at 40 ⁰ C and is selected from the group consisting of urea, solid alkyl substituted ureas which contain a total of up to 9 carbon atoms, thiourea, biuret, £ -Caprolactaa , solid aliphatic amides containing up to 6 carbon atoms, solid polyhydric compounds and ammonium carboxylate salts, about 5 to 80% by weight of at least one diluent to reduce viscosity from the group of water, liquid polyhydric compounds, liquid alkyl-substituted compounds Urea with up to 9 carbon atoms in the alkyl group, liquid aliphatic amides with up to 6 carbon atoms contain, and dimethyl sulfoxide, and 0 to about 60 wt.% Diluent or diluents from the group of starch, dextrin, clay, silica BZV /. Silica, carbon black, talc, calcium carbonate, barium sulfate and vinyl polymer latices, provided that when the viscosity lowering diluent is present in an amount above 45% by weight, the adhesive composition is a suspension and the polymer is polyvinyl alcohol which is heat treated at a temperature of at least 50 ⁰ C, dispersed in a treatment liquid that has a ca-. containing up to 20 percent by weight acetic acid in a solvent - 44 - 809842/0087 ORIGINAL INSPECTED Methanol or methyl acetate, or a mixture of methanol and methyl acetate containing, was subjected, the polyvinyl alcohol being ^{insoluble in water at 20 0} C, but its solubility in water at Te nip era door he. baibehält over 70 ^0C. Composition according to Claim 1, characterized in that the adhesive composition is a homogeneous system which essentially contains or consists of: about 10 to 35% by weight of a polymer from the group consisting of polyvinyl alcohol and ethylene / vinyl alcohol copolymers containing at least 50 % MoI-Jo vinyl alcohol, about 40 to 80% by weight of at least one crystalline solvent for the polymer and about 5 to 45% by weight of at least one diluent to lower the viscosity. 3. Composition according to claim 1, characterized in that the adhesive composition is a heterogeneous system, which contains or consists essentially of. About 5 to 25 wt% of a polymer from the group of polyvinyl alcohol and ethylene / vinyl alcohol copolymers containing at least 50 95 mol of vinyl alcohol, about 10 to 45 wt. SS of at least one crystalline solvent for the polymer and about 20 to 40 wt. 56 of at least one diluent to lower the viscosity and about 5 to 60 wt. . . 4. Composition according to claim 1, characterized in that that the adhesive composition is a suspension, which essentially contains or consists of: about 2 to 35 wt. # Polyvinyl alcohol, wherein the polyvinyl alcohol is a heat treatment at a temperature of 70 ° to 190 ⁰ C, dispersed in a liquid solvent containing 42 Ms 100 wt. 9i methanol, 0 to 13 wt.% water, and 0 to 45 wt.% of a solvent from the group of 2 to 5 carbon atoms containing monohydric alcohols, esters, ketones, ethers, hydrocarbons and chlorinated hydrocarbons, wherein - 45 - AD 4754A 3 2 7 1 5 A 3 4 the polyvinyl alcohol is insoluble, has been treated to reduce to the content of cold-water soluble substances in the polyvinyl alcohol, but its solubility is maintained in water at 30 ° to 100 ⁰ C, about 15 to 68 weight.% crystalline of at least one Solvent for the polymer and about 30 to 80% by weight of at least one diluent to lower the viscosity. 5 · Curable, homogeneous adhesive composition according to at least one of claims 1 to 4, characterized in that it contains a hardener from the group (a) about 2 wt.% titanium citrate, and about 2 to 4 Gew.55 Glykollsäure or citric acid, based on the weight of the adhesive, and (b) About 1 to 20% by weight , based on the weight of the adhesive, of a resole which, by heating for about 15 minutes at about 90 to 95 ° C., of about 1 part by weight of resorcinol, about 1 part by weight of urea and about 1 to 3 parts by weight of 375oigeni formalin, provided that the hardening agent (b) is only used in hydro-hot melt adhesives in which the viscosity-reducing thinner is water. 6. Composition according to at least one of claims "to 5, characterized in that it additionally" contains up to about 10 % by weight of at least one extender or co-solvent from the group consisting of starch, dextrin, clay, silicon dioxide or silica, carbon black, talc , Calcium carbonate, barium sulfate and / or vinyl polymer latices. 7. Composition according to at least one of the claims "to 6, characterized in that they contain about 0.05 to 0.5% by weight Contains guar gum. - 46 - 809842/0087 AD 4754A 2 7 1 5 ü 3 A 8. Composition according to at least one of claims 1 Ms 6, characterized in that it contains about 0.1 to 0.3 wt.% Guar gum. 9. Method of gluing at least two. Substrates, characterized in that at least one substrate is coated with at least one of the adhesive compositions according to Claims 1 to 8, a second substrate is brought into contact with the adhesive layer and both substrates are glued to one another. 10. Ancestors for bonding two substrates, thereby marked that one (1) one after the other or simultaneously both substrates with at least one adhesive composition of claims 1 to 8 brings in contact and (2) Cools down to fully develop the perfect binding. 11.. Process according to claim 10, characterized in that one (1) the composition melts, (2) applying the molten composition to a first substrate, (3) a second substrate with the molten composition brings into contact on the first substrate, and (4) Cool the composition to develop the adhesive bond. 12. Ancestors according to claim 11, characterized in that that the critical solvent for the polymer is urea. - 47 - 809842 / ΟΟΘ7 AD 4754A 5 "27 15 13. The method according to claim 10, characterized by that he (1) a solid film of the adhesive composition manufactures, (2) treated the film with a first substrate, (3) apply heat to bond the film and the first substrate, (4) the second substrate with the adhesive composition brings into contact on the first substrate, (5) Apply heat to bond the second substrate to the first substrate and (6) the adhesive composition cools to fully develop the adhesive bond. 14. The method according to claim 13, characterized in that the crystalline solvent for the polymer is urea is. 15. Structure, characterized in that it is at least Contains two cellulose substrates which are bonded to one another by at least one of the compositions of claims 1 to 8 are. 16. Structure, characterized in that it has at least one of the adhesive compositions of claims 1 to 8 was bonded, wherein the composition as crystalline Solvent for the polymer urea or ε-caprolactam contains. - 48 - 809842/0087