GB1574478A

GB1574478A - Elastomer melamine resins

Info

Publication number: GB1574478A
Application number: GB51017/77A
Authority: GB
Original assignee: Formica Corp
Current assignee: Formica Corp
Priority date: 1977-12-07
Filing date: 1977-12-07
Publication date: 1980-09-10

Description

(54) ELASTOMER MODIFIED MELAMINE RESINS (71) We, FORMICA CORPORATION, a corporation organized and existing under the laws of the State of Delaware, United States of America, of 120 East Fourth Street, Cincinnati, State of Ohio, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to elastomermodified melamine resin compositions useful in the production of heat- and pressure-consolidated articles, particularly decorative surfaced panels.

The production of decorative surfaced panels designed for such applications as furniture and vertical surfaces where exceptionally high abrasion resistance is not required has increased enormously over the past decade. These panels comprise a single sheet of melamine/formaldehyde resin impregnated decorative paper which is bonded under heat and pressure to a substrate, usually particle board, of about one-quarter to about one inch in thickness.

These products, because they are produced at low pressures, i.e. about 300 psi, and at very short cure cycles, i.e., 2-3 minutes.

are relatively inexpensive and have a good appearance and stain resistance.

Abrasion resistance thereof is however, often poor and attempts have been made to improve the property by providing a layer of clear, unfilled melamine/formaldehyde resin on top of the decorative sheet. While these panels have proven very successful in that the abrasion resistance is adequately increased, they deteriorate when subjected to humidity conditions encountered in normal use. This deterioration manifests itself as surface cracks in the panel after it is subjected to low humidity. The cracks are believed to be a result of the dimensional instability of the melamine/formaldehyde resin. These resins undergo dimensional changes owing (1) to loss of water during curing, (2) to cooling after release from the panel press and (3) to loss or gain of water during subsequent exposure to the environment.The dimensional changes are often enough to strain the resin to failure, thus forming cracks. The decorative cellulosic sheet aids in the resistance of the panel to cracking, but its effectiveness is limited by the need for a resin-rich surface to impart abrasion resistance.

Known additives which generally have been added to melamine/formaldehyde resins (such as sucrose and pentaerythritol sebacate, so as to react with the resin and reduce the tightness of cross-linking usually associated with brittleness do not prevent cracking to a satisfactory degree.

It is, therefore, clear that there remains a need for a melamine/formaldehyde resin formulation which can be carried as a transparent film on top of a decorative print sheet in decorative panels to thereby confer abrasion resistance thereto, which will not crack when the panel is subjected to low humidity and will still retain the desirable properties of melamine/formaldehyde resins per se, including transparency and resistance to heat and staining.

This invention comprises a novel melamine/formaldehyde resin formulation which can be impregnated into decorative cellulosic sheets and heat and pressure consolidated into decorative surfaced panels, which resin will not crack at the panel surface upon subjection thereof to low humidity. Furthermore, the invention also comprises the heat and pressure consolidated panel which not only does not crack upon subjection to low humidity but also retains its heat resistance, transparency and abrasion resistance.

These results are achieved by the incorporation of an elastomer latex into the melamine/formaldehyde resin in the form of fine particles and impregnating the resultant composition into the decorative sheet.

Although not wishing to be bound by any specific theory as to why the instant compositions accomplish the result they do, the following discussion is believed particularly pertinent.

It is generally well founded that when a glassy polymer, such as a melamine/formaldehyde resin, is stressed sufficiently either in impact or in tension, crazes and cracks develop. A craze differs from a small crack in that a craze is partially filled with a network of polymer molecules pulled from the walls and. serving as a potential healing mechanism. Crazes are usually initiated by high local stress concentrations in the vicinity of flaws or crack tips. Rate of craze growth depends on the fracture energy of the resin, the applied forces and the temperature. If liquids are present. they may diffuse to the craze front, plasticize the area and assist in craze growth. Ultimately, fracture results from the breaking of the crazed material.

Elastomeric particles, on the other hand, can prevent failure by either or both of two general mechanisms. By the first mechanism, the distorted stress field around each particle initiates microcrazes. These microcrazes multiply and grow, but large amounts of energy are absorbed and a stabilized network soon forms. The system thus supports a higher elongation than in the absence of particles and returns, on release of stress, to its original state. By the second mechanism, which may operate independently, the stress field causes shear bands to develop from the particles into the matrix. Shear banding is a form of yielding and orientation usually accompanied by strain hardening. Thus a stabilized network forms in this case as well.

It thus appears probable that the elastomers incorporated into the melamine/formaldehyde resin to produce the instant compositions, function as described above to reduce craze and cracks when the resin-elastomer composition is impregnated into cellulosic sheets which are then consolidated into the decorative panels and utilized at low humidity.

Mixtures of melamine/formaldehyde resins and rubbery polymers have been known in the art, see British Specification No. 1417421, but said specification does not disclose the elastomer components set forth as useful herein.

The invention in its broadest aspect is a composition comprising a mixture of (1) an aqueous melamine/formaldehyde resin solution, (2) from 2.5% to 30.0% by weight, based on the weight of the resin solids of(l), of an elastomer comprising: (a) an ethylene/vinyl chloride copolymer containing from 0.5% to 7.0%, by weight, based on the total weight of (a), of units containing amide groups or (b) a polyurethane elastomer containing from 3.0 /O to 10.00/, by weight, based on the total weight of (b), of carboxyl groups, said elastomer having a particle size of up to 20,000 A.

The heat and pressure consolidated structure comprises in superimposed relationship, (A) a self-supporting substrate and (B) a decorative paper sheet impregnated with the above-enumerated composition.

The melamine-formaldehyde resin syrups useful herein are well known to those skilled in the art. Typically, they are prepared by adding water, melamine crystal, formaldehyde, usually used as a 37% solution in water, and other additives in minor amounts, to water in mole ratio of melamine to formaldehyde of from 1:1.6 to 1:2.5 and allowing the reaction to proceed at 75-900C. for- 5-12 hours. Sufficient material is added to produce a resin solids content of from 40% to 75%, preferably from 50 /n to 65%, in the resultant aqueous solution.

The elastomer component of the compositions is added to the melamine/formaldehyde resin in such a quantity so as to result in a solids content of the elastomer of from 2.5% to 30.0%, preferably from 5.0% to 25.0%, by weight, based on the total weight of the melamine/formaldehyde resin solids.

The elastomer is preferably added to the melamine/formaldehyde resin solution as small particles and usually in latex form.

The particle size in most instances should not exceed 4,000 A; however, it is possible, in some cases, to utilize elastomers having a particle size, on the average, of up to 20,000 A. Where it is required that the compositions produce a transparent system, e.g., in the production of decorative panels of a specific color or having a specific decorative pattern or design on the decorative layer, it is preferred that the elastomeric additive have a particle size of less than 1,000 A. Alternatively, haziness can be reduced, i.e., transparency can be achieved by matching the refractive index of the elastomer to that of the melamine/formaldehyde resin. The combination of a particle size less than about 1,000 A and a matching refractive index will, of course, further enhance the usefulness of the elastomer.

One class of elastomeric materials which have been found to be effective in producing the compositions and laminates of this invention are the ethylene/vinyl chloride polymers containing from 0.5% to 7.0 by weight of units containing amide groups. These copolymers are well known in the art and typically contain from 20% to 30% ethylene, from 65% to 80% vinyl chloride and from 0.5% to 7%, preferably from 1.0% to 5.0%, of units containing amide groups, said percentages totalling 100% and being, by weight, based on the total weight of the elastomer. The amide functionality can be imparted to the ethylene/vinyl chloride copolymer in any manner known to those skilled in the art such as by copolymerization thereof with amide containing vinyl monomers, e.g.

acrylamide or methacrylamide, see United States Patent 3,428,582.

The useful polyurethane elastomers, which form another class of elastomers which may be employed in the compositions of this invention, are governed only by their ability to either dissolve in water or to form a latex. That is to say, if the polyurethane elastomer is per se water-soluble, it can be added as such to the aqueous melamine/formaldehyde resin solution and produce a composition which may be used to prepare a useful laminate. Alternatively, if the polyurethane elastomer is capable of being formed into a latex, the latex can be added to the aqueous melamine/ formaldehyde resin solution and the elastomer will, of course, remain dispersed therein. The resultant dispersion can then be used to impregnate the decorative sheet and form the decorative panel.

Suitable polyurethane resins can be produced by reacting such polyols as those having a molecular weight of from 400 to 5,000, preferably from 600 to 3,000, with an isocyanate. Useful polyols include those produced from diols such as the polyoxyalkylene adducts of diols and alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide and mixtures thereof. Useful diols include ethylene glycol, 1,2-propylene glycol, 1,3propylene glycol, 1,2-butanediol, 1,4butanediol, 1,6-hexanediol, hydroquinone and bisphenol A.

Typical polyoxyalkylene diols include polyethylene-ether glycol, polypropyleneether glycol and polytetramethylene-ether glycol.

Polyoxyalkylene arylene diols which also have molecular weights ranging from 400 to 5,000 but which differ from the abovedescribed polyoxyalkylene diols in having arylene radicals, such as phenylene, naphthylene and anthrylene radicals, either unsubstituted or substituted, e.g., with alkyl or aryl groups, in place of some of the alkylene radicals of said polyoxyalkylene diols may also be employed.

Polyoxyalkylenearylene glycols of the type ordinarily used for this purpose will usually contain at least one alkylerie ether radical having a molecular weight of about 200 for each arylene radical present.

Essentially linear polyesters constitute another class of reactive organic diols which may be employed in preparing the urethane prepolymers useful in the present invention.

While the preparation of polyesters suitable for this purpose has been described in great detail in the prior art and forms no part of the present invention per se, it may be mentioned here by way of illustration that polyesters of this type may be prepared by the condensation of a dihydric alcohol, generally a saturated aliphatic diol such as ethylene glycol, propanediol-1,2, propanediol-1,3, butanediol-1,4, pentanediol-l 2, pentanediol- 1,5, hexanediol-1,3, hexanediol-1,6, diethylene glycol, dipropylene glycol, triethylene glycol and tetraethylene glycol, as well as mixtures of such diols with each other, with a dicarboxylic acid, e-caprolactone, or anhydride which is either saturated or which contains only benzenoic unsaturation, such as oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, terephthalic, sebacic, malic, phthalic, cyclohexanedicarboxylic and endomethylenetetrahydrophthalic acid, and their isomers, homologs, and other substituted derivatives, e.g., chloro derivatives. The linear polyesters used in preparing the urethane prepolymers also generally have molecular weights ranging from 400 to 5,000. In addition, they generally have relatively low acid numbers, e.g., acid numbers not appreciably in excess of 60 and preferably as low as can be practicably obtained, e.g., 2 or less. Correspondingly, they have relatively high hydroxyl numbers, e.g., from 20 to 300.

When preparing these polyesters, an excess of diol over dicarboxylic acid is generally used.

As can be readily appreciated, mixtures of the various reactive organic diols described hereinabove may also be employed in preparing the urethane prepolymers useful in the present invention.

The organic diisocyanates which can be employed to produce the urethane elastomers useful in the present invention include, for example, the aliphatic, cycloaliphatic and aromatic diisocyanates including m-xylene diisocyanates, methylenediisocyanate, tetramethylenediisocyanate, hexamethylene diisocyanate, 4,4' - methylenebis (cyclohexyl isocyanate), 4 - chloro - m phenylene diisocyanate, isophorone diisocyanate, o, p, or m- phenylene diisocyanate, trimethylhexamethylene diisocyanate, 4 - t - butyl - m - phenylene diisocyanate, 4,4' - methylene bis(phenyl isocyanate), tolylene diisocyanate, 1,5naphthalene diisocyanate, 4- methoxy m - phenylene diisocyanate, biphenylene diisocyanate, cumene - 2,4 - diisocyanate, 3,3' - dimethyl- 4,4' - biphenylene diisocyanate, p,p' - diphenylene diisocyanate, 3,3' - dimethoxy - 4,4' biphenylene diisocyanate and mixtures thereof.

The polyol may be reacted with the diisocyanate in the presence of a suitable catalyst such as an organotin compound, e.g., dibutyltin dilaurate and dibutyltin octoate; a tertiary amine, e.g., triethylene diamine; an organolead compound, e.g., lead octoated, at concentrations of from e.g.

0.001 to 0.1If^, by weight, based on the total weight of the polyol and diisocyanate. The reaction is generally allowed to proceed at a temperature of from 60"C to 1800C. until the isocyanate terminated urethane prepolymer forms, i.e., from 4 to 24 hours.

As mentioned above, in order for the polyurethane elastomer to be useful herein, it must contain carboxyl groups. These carboxyl groups, present in the elastomer in a concentration of 3.0% to 10.0%, by weight, based on the total weight of the elastomer, may be incorporated into the elastomer by replacing an equivalent amount of the above mentioned polyol with a polyol containing at least one carboxyl group.

Suitable compounds conforming to this description are 2,2 - dimethylol propionic acid, tartaric acid, glyceric acid, bis (hydroxymethyl)benzoic acid and bis(hydroxymethyl)cyclohexane carboxylic acid. United States Patent 3,479,310 teaches the production of such carboxylcontaining polyurethanes.

The compositions of the instant invention may be prepared by blending the elastomer per se after having emulsified it with a suitable amine such as triethanol amine, Nmethyl morpholine, tetramethyl ammonium hydroxide, triethylamine and tetrabutylammonium hydroxide, with the aqueous melamine/formaldehyde resin solution, with stirring for e.g. from 3-15 minutes.

Catalyst, such as ammonium sulfate, thiourea, hydrochloric acid, sulfuric acid formic acid, acetic acid, oxalic acid, sodium hydroxide, potassium hydroxide and sodium carbonate, can be added at this time to regulate subsequent cure rate of the melamine/formaldehyde resin when the decorative sheet containing it is heat and pressure consolidated into the decorative panel. The use of a strong acid catalyst when a basic emulsifier is used to produce the elastomer latex should be avoided.

The aqueous melamine/formaldehyde resin solution can be used as such or the resin itself and/or the solution. Often called a "syrup", it may be further modified by the addition of known additives thereto.

The blending of the prepared elastomer with the melamine/formaldehyde resin solution is the preferred manner in which the compositions of this invention may be prepared. It is also possible, however, to form the elastomer in situ in the melamine/formaldehyde solution by incorporating therein a solution of the elastomer components and then forming the elastomer during the melamine/ formaldehyde precuring operation and/or the decorative panel production.

The decorative papers from which the low-pressure panels of the present invention are preferably produced are made from bleached wood pulp which is high, at least 60%, in alpha cellulose content. The papers are pigmented in a known manner to obtain the desired levels of color and opacity. They generally have a basis weight of at least 40 pounds per 3,000 square foot ream. The paper should have controlled pH of about that of the melamine/formaldehyde resin due to the influence pH has on the reaction rate of the melamine resin after it is applied thereto.

The decorative surface paper porosity (Gurley) is preferably controlled to assure proper treating of the paper with the resin and pressing of the panel. A paper having too high a porosity will allow too much resin to penetrate while a paper with too low a porosity will not enable sufficient resin to penetrate.

Impregnation of the paper and drying of the impregnated paper may be effected by conventional treaters and driers at e.g., 8 125"C. for 3-50 minutes. Treaters which have been found to be particularly useful in this regard achieve a high resin pick-up and uniform surface coating with sufficient surface resin to achieve an acceptable abrasion resistance. The impregnated paper generally contains at least 40% resin, by weight, based on the weight of the impregnated paper.

Core material, i.e., self-supporting substrates useful in producing the decorative low-pressure panels include medium density, mat-formed, wood particle board and medium density, wood fibreboard. Useful core material, however, merely must enable the production of fullsized, smooth-faced, well bonded, crack and craze resistant panels. Core materials should be stored for a sufficient time at ambient conditions to achieve an equilibrium temperature and an equilibrium moisture content.

The decorated layer may be placed on both sides or only on one side of the selfsupporting substrate when panels are being produced. If the decorative sheet is placed only on one side of the substrate, it is preferred that a so-called balance sheet, i.e., a melamine-formaldehvde resin impregnated paper sheet, e.g., of kraft or other paper, sometimes called a cabinet liner, be placed on the other side in order to prevent the resultant panel from warping during pressing.

Typical release sheets can be applied to both the decorative layer and the balance sheet to prevent the press plate from sticking thereto.

Various finishes may be applied to the decorative panels of the present invention.

For example, the surface may be rendered glossy by using a highly polished press plate, matte by interposing a texturizing release sheet between the press plate and the decorative sheet or embossed by using an etched press plate.

The following examples illustrate the invention. All parts and percentages are by weight unless otherwise specified.

The Taber Abrasion Resistance Test mentioned below is specifically detailed in N.E.M.A. Standards Publication "Laminated Thermosetting Decorative Sheets", Standard No. LDI-2,01 "Method of Test of Resistance of Surface to Wear".

Example A Preparation of a Polyurethane Emulsion To a suitable reaction vessel equipped with stirrer, thermometer, N2 gas inlet and vacuum adapter are added 44.2 parts of polytetramethylene glycol having a molecular weight of 2,000 and 11.9 parts of 2,2 - bis(hydroxymethyl)propionic acid.

The vessel is heated to 1000C. and a 1-2 mm. Hg. pressure for 2 hours to dry the glycol and acid. A blanket of nitrogen gas is then maintained over the vessel contents and the vessel is cooled to 40"C. 43.9 parts of toluene diisocyanate are then added and the exotherm is controlled at 800 C. for 8 hours. The vessel is then cooled to 600 C.

and the resultant polyurethane polymer is transferred to a second vessel and sealed under nitrogen.

To a third vessel are added 7.0 parts of triethanol amine, as an emulsifier, in 90 parts of water. The vessel is cooled to 40C.

The cooled solution is transferred to a fourth vessel which has been cooled to OOC, and is equipped with vigorous agitation means. The solution is vigorously agitated and 30.0 parts of the above-prepared polyurethane polymer are heated to 1000C.

and added to the vortex of the agitating solution in a continuous stream. When addition is complete, 10.0 parts of chipped ice are added and stirring is continued 1 minute. Another 10.0 parts of chipped ice are added and the mixture is again agitated for 1 minute. The vessel contents are then transferred to a suitable container, cooled to < 100C. and stirred for 5 hours while the temperature slowly rises to ambient. A clear, blue opalescent emulsion of 25 ,; solids is recovered. Small amounts of coagulum which may be present therein are removed by filtering the emulsion through a No. 1 Whatman paper. The average particle size of the elastomer is less than 1,000 A.

Example 1 100 Parts of a commercially available 1:1.8 melamine/formaldehyde resin syrup (58 /n solids) are added to a suitable reaction vessel. The liquid is stirred and 0.05 part of ammonium sulfate catalyst is added thereto.

To the resultant mixture are then added 34.8 parts of the polyurethane emulsion of Example A. Stirring is continued for 5 minutes. A stable emulsion is recovered.

A large section of woodgrained print paper is impregnated with the resultant stable emulsion. The impregnated sheet is precured in an air circulating oven. The precured paper sheet is then placed atop a particleboard section of the same size with the decorative side up and a release sheet is placed on top of the decorative side thereof.

The assembly is placed between 2 steel press plates, slid into a hydraulic press heated to a platen temperature of about 155"C. and pressed at 250--350 psi for 2-3 minutes.

The resulting surface layer of polyurethane modified resin is transparent and about 45 y thick. The panel is removed from the press and treated.

The low humidity cracking resistance thereof is determined by placing the decorative panel into an indicating CaSO4 conditioned desiccator at 0% R.H. and counting cracks formed at intervals during 30 days through a stereomicroscope.

Abrasion resistance is determined as set forth above. The Taber cycles to 50 /" print erasure are 250. No cracks appear after 30 days.

Examples 2-16 Following the procedure of Example 1, additional decorative panels are prepared.

The thickness of the resin layers is varied as is the precentage of the polyurethane. The results are set forth in Table I, below.

TABLE I Taber Cycles No. Cracks Surface Resin to 50% Print after 30 days Example % Polyurethane Thickness u Erasure at 0% R.H.

2 21 35 370 0 3 5 25 300 0 4 10 45 350 0 5 10 20 200 0 6 10.8 25 200 0 7 10.8 15 170 0 8 8.9 20 230 0 9 10.8 45 330 0 10 7.5 45 310 0 11 (comp) 0 0 70 0 12(comp) 0 8 80 20 13(comp) 0 30 350 50 14(comp) 0 45 310 > 50 15(comp) 0 35 350 > 50 16(comp) 0 40 360 > 50 Example 17 Again following the procedure of Example 1 except that 10% of a commercially available ethylene/vinyl chloride (18/77) copolymer containing 5% of amide-containing units, is used instead of the polyurethane, a smooth, clear film results on the decorative panel. The average particle size of the copolymer is about 775 A.Precuring followed by laminating as described in Example 1 results in panels having a Taber value of 140170. No cracks are observed after 40 days at 0% R.H. The decorative pattern is readily observable.

Example 18 The procedure of Example 1 is again followed except that a commercially available poly(ethylene adipate) of 1700 molecular weight and having terminal hydroxyl groups is used as the polyol.

Similar results are achieved, the polyurethane elastomer having been added to the melamine/formaldehyde resin solution by suspending it in the aqueous phase thereof. Particle size of the urethane is about 1,000 A.

Example 19 A bisphenol A-ethylene oxide adduct of 2,800 molecular weight is used as the polyol in place of that of Example 1. Again an excellent decorative panel with no cracks after 35 days at 0% R.H. is produced. The particle size of the polyurethane is about 1,500 A.

Example 20 The procedure of Example 1 is again followed except that the particle size of the elastomer in the emulsion is about 3,800 A and a white decorative sheet is used. A panel having excellent crack resistance at 0% R.H. and a somewhat cloudy surface is produced.

As can be seen from Example 20, the use of the above-described melamine/formaldehyde resin-elastomer composition sometimes results in a cloudy -or hazy surface on the resultant laminate.

This haziness cannot only be reduced by reducing the particle size of the elastomer, as mentioned above, but by incorporating into the resin-elastomer mixture, an alkylene polyamine diamine or polyalkylene polyamine. Not only does the use of the alkylene polyamine solve the problem of haze formation, but it also enables the reduction, or elimination altogether, of the curing catalyst used to bring the resinelastomer blend to the B-stage once it is impregnated into the cellulosic decorative sheet. Additionally, when using an alkylene polyamine diamine or polyalkylene polyamine, the elastomers useful in the preparation of the resin-elastomer blend can be broadened to include a butadiene/acrylonitrile copolymer containing from 1% to 10% by weight of carboxyl groups.

The butadiene/acrylonitrile copolymers useful in this aspect of the invention contain available carboxyl groups and generally comprise from 5095% of butadiene and, correspondingly, from 5-50% of acrylonitrile. Carboxylation of the copolymer in amounts ranging from 1-10% can be achieved by replacing a portion of either of the comonomers with a carboxyl group-containing monomer or carboxylating the copolymer.

The alkylene diamine and polyalkylene polyamine can be added to the compositions before or after the melamine/formaldehyde resin and elastomer have been blended or it can be added to either the elastomer or the resin and then the remaining component can be added, the particular method of blending the ingredients forming no part of the instant invention.

The alkylene diamines and polyalkylene polyamines employed have the general formula: H2N-[-CH2CH2NH-] nCH2CH2NH2 wherein n isO, 1, 2 or 3. Examples of useful di- and polyamines include ethylene diamine, diethylenetriamine, triethylene tetramine and tetraethylene pentamine.

The di- and polyamines are incorporated into the formulations in amounts ranging from 0.25 to 1.25%, by weight, based on the total solids, i.e., the melamine/formaldehyde resin and the elastomer, of the composition.

Blending of the prepared elastomer with the melamine/formaldehyde . resin solution and di and polyamine is the preferred manner in which the compositions useful herein may be prepared. It is also possible, however, to form the elastomer in situ in the melamine/formaldehyde solution containing the alkylene diamine or polyalkylene polyamine by incorporating therein a solution of the elastomer components and then forming the elastomer during the melamine/formaldehyde precuring operation and/or the decorative panel production.

Example 21 100 Parts of a commercially available 1:1.8 melamine/formaldehyde resin syrup (58% solids) are added to a suitable reaction vessel. The liquid is stirred and 1.0 part of tetraethylene pentamine is added thereto.

To the resultant mixture are then added 30.0 parts of the polyurethane emulsion of Example A. Stirring is continued for 5 minutes. A stable emulsion is recovered.

A large section of woodgrained print paper is impregnated with the resultant stable emulsion and formed into a decorative laminate as in Example 1. The Taber cycle to 50% print erasure are 210.

Only 10 microcracks appear after 30 days.

No haze is visible to the naked eye, whereas, without the pentamine, a slight haze is detectable.

Examples 22-27 Following the procedure of Example 21, additional decorative panels are prepared.

The percentage of the pentamine is varied as is the percentage of the polyurethane and the precuring cycle. The results are set forth in Table II, below. In each case, the decor sheet was clearly visible as a sharp, contrasting pattern.

TABLE II Taber Cycles No cracks to 50% Print after days Example % Polyurethane % Pentamine Erasure at 0% R.H.

22 8.1 1.0 300 7-30 days 23 8.1 0.2 310 0--28 days 24 8.1 0.4 170 W28 days 25 8.1 0.4 300 0-28 days 26 8.1 0.6 280 0--28 days 27 8.2 0.6 240 W28days *=(NH4)2SO4 added as cat.

Example 28 Again following the procedure of Example 21, except that 10% of a commercially available ethylene/vinyl chloride (18/77) copolymer containing 5% of units containing amide groups is used instead of the polyurethane, a smooth, clear film results on the decorative panel. The average particle size of the copolymer is about 775 A. Precuring followed by laminating as described in Example 1 results in panels having a Taber value of 140-170. No cracks are observed after 40 days at 0% R.H. The decorative pattern is clearly visible to the naked eye.

Example 29 The procedure of Example 21 is again followed except that the particle size of the elastomer in the emulsion is about 3,200 A and a blue decorative sheet is used. A panel having excellent crack resistance at 0% R.H. and a clear blue sparkling surface is produced.

Example 30 The procedure of Example 21 is again followed except that the polyurethane is replaced by 21% of a commercially available butadiene/acrylonitrile (80/20) copolymer containing 3.5% carboxyl groups and a white decor sheet is used. A sharp, bright decorative panel is recovered which exhibits excellent crack resistance at low humidity and possesses no haze visible to the naked eye.

Examples 31-33 When the tetraethylene pentamine of Example 21 is replaced by an equivalent amount of (31) ethylene diamine, (32) diethylene triamine and (33) triethylene tetramine, substantially identical results are achieved.

Examples 34-35 When the procedure of Example 28 is again followed except that (34) ethylenediamine and (35) triethylene tetramine are substituted for the tetraethylene pentamine thereof, the results are again substantially equivalent.

Example 36 The use of diethylenetriamine in Example 30 as a replacement for the tetraethylene pentamine thereof achieves identical results.

The instant invention also contemplates the use of ethylene glycol or a polyethylene glycol, in the resin-elastomer mixture to increase the abrasion resistance of a decorative laminate produced from the composition. The ethylene glycol or polyethylene glycol can be used in the absence or the presence of the alkylene diamine or polyalkylene polyamine haze reducing additive, and when used, the elastomer may be a butadiene/acrylonitrile copolymer containing from 1% to 10% by weight carboxyl groups whether or not an alkylene amine haze reducing additive is also present.

The ethylene glycol or a polyethylene glycol can be used as a reactant with the melamine and formaldehyde in producing the resinous material or the melamine and formaldehyde can be first reacted to produce the resinous material and then the ethylene glycol or a polyethylene glycol can be added thereto. After the resinous melamine/formaldehyde material as produced, in concentrations and in the manner set forth hereinabove, the ethylene glycol or polyethylene glycol can be added in aqueous solution to the aqueous solution of the resin in amounts ranging from 2 0In to 20.00/,, by weight, based on the resinous solids.Alternatively, when the ethylene glycol is added with the melamine and formaldehyde to the reaction vessel, it can be added in the same quantity, by weight, as above, based on the total weight of the melamine and formaldehyde charge materials.

The polyethylene glycols employed herein have the general formula: HO[CH2CH2O]nH wherein n is an integer of 245, inclusive, i.e., sufficient to produce a material having a molecular weight of up to 2,100. Useful polyethylene glycols include diethylene glycol and those commercially available polyethylene glycols having molecular weights of e.g. 600 or 2,000. The ethylene glycol or polyethylene glycols are incorporated into the compositions in amounts ranging from 2.0% to 20.0 ,/, by weight, based on the total weight of melamine and formaldehyde monomers.

Example 37 45.2 Parts of a 37% formalin solution, 38.5 parts of crystalline melamine, 12.2 parts of water and 1.2 parts of diethylene glycol are charged to a suitable reaction vessel and heated to about 90"C. for about 2 hours.

0.05 Part of ammonium sulfate catalyst and 1.03 parts of the polyurethane elastomer of Example A, above, are then added.

A large section of woodgrained print paper is impregnated with the resultant catalyst containing resin solution, precured and formed into a decorative laminate as in Example 1. The resultant panel has 0 cracks after 35 days at 0% R.H. and a Tabler Cycle to Failure of 230.

Example 38 To a suitable reaction vessel are charged 46.0 parts of a 37% formalin solution, 39.4 parts of melamine crystal, 12.3 parts of water and 2.4 parts of polyethylene glycol having a molecular weight of 380420. The condensation is run for about 1 hour at 900 C. When formed into a panel as in Example 1, after adding 4.1 parts of the polyurethane elastomer of Example A, except that the press temperature is about 1600C., the resultant panel has a good appearance, shows no cracks after 30 days.

Example 39 When Example 37 is again followed except that 1% of tetraethylene pentamine is also added, 0 cracks form after 35 days at 0% R.H. and the Taber Cycles to Failure is 300.

Example 40 Again following the procedure of Example 38 except that 10% of a commercially available ethylene/vinyl chloride (18/77) copolymer containing 5% of units containing amide groups is used instead of the polyurethane, a smooth, clear film results on the decorative panel. The average particle size of the copolymer is about 775 Â. Precuring followed by laminating results in panels having good abrasion resistance. No cracks are observed after 20 days at 0% R.H.

Example 41 The procedure of Example 38 is again followed except that the elastomer is replaced by 210/, of a commercially available butadiene/acrylonitrile (80/20) copolymer containing 3.5% carboxyl groups. A sharp, bright decorative panel is recovered which exhibits good crack resistance at low humidity and possesses no cracks after 20 days at 0% R.H.

Examples 42--44 When the tetraethylene pentamine of Example 39 is replaced by an equivalent amount of (42) ethylene diamine, (43) diethylene triamine and (44) triethylene tetramine, substantially identical results are achieved.

Example 45 To 40 parts of a 1:1.6 melamine/ formaldehyde resin syrup at 58% solids are added 4.4 parts Qf ethylene glycol.

The blend is stirred to achieve a good admixture and ammonium sulfate is added as a catalyst. A laminate is then made from the resultant syrup as in Example 37.

Example 46 When the procedure of Example 45 is again followed except that the ethylene glycol is replaced by 2.9 parts of a commercially available polyethylene glycol of a molecular weight of about 2,000, good results are observed.

WHAT WE CLAIM IS: 1. A composition comprising a mixture of (I) an aqueous melamine/formaldehyde resin solution, (2) from 2.5% to 30.0% by weight, based on the weight of the resin solids of (1), of an elastomer comprising: (a) an ethylene/vinyl chloride copolymer containing copolymer from 0.5% to 7.0%, by weight based on the total weight of (a), of units containing amide groups or (b) a polyurethane elastomer containing from 3.0% to 10.0% by weight, based on the total weight of (b), of carboxyl groups, said elastomer having a particle size of up to 20,000 A.

2. A composition comprising a mixture of (1) an aqueous melamine/formaldehyde resin solution, (2) from 2.5% to 30.0% by weight, based on the weight of the resin solids of (1), of an elastomer comprising: (a) an ethylene/vinyl chloride copolymer containing from 0.5% to 7.0In, by weight, based on the total weight of (a), of units containing amide groups, (b) a polyurethane elastomer containing from 3.00,n/ to 10.0%, by weight, based on the total weight of (b), of carboxyl groups, or (c) a butadiene/acrylonitrile copolymer containing from 1% to 10% by weight, based on the total weight of (c), of carboxyl groups, said elastomer having a particle size of up to 20,000 A, and (3) from 0.25 to 1.25% by weight, based on the total weight of solids in said coniposition, of an alkylene diamine or a polyalkylene polyamine.

3. A composition according to Claim 2, wherein said (3) is tetraethylene pentamine or triethylenetetramine.

4. A composition comprising: (1) a blend of an aqueous melamine/formaldehyde resin solution and from 2% to 20%, by weight, based on the solids weight of said resin, of ethylene glycol or a polyethylene glycol having a molecular weight of up to 2,100, or (2) an aqueous solution of the resinous reaction product of (I) melamine, (II) formaldehyde and (III) from 2% to 20.0%, by weight, based on the total weight of melamine and formaldehyde, of ethylene glycol or a polyethylene glycol having a molecular weight up to 2,100, and (3) from 2.5 to 30.0%, by weight, based on the weight of resin solids, of an elastomer comprising:: (a) an ethylene/vinyl chloride copolymer containing from 0.5% to .7.0%, by weight, based on the total weight of (a), of units containing amide groups, (b) a polyurethane elastomer containing from 3.0% to 10.0%, by weight, based on the total weight of (b), of carboxyl groups, or (c) a butadiene/acrylonitrile copolymer containing from 1% to 10%, by weight, based on the total weight of (c), of carboxyl groups, said elastomer having a particle size of up to 20,000 .

5. A composition according to Claim 4, wherein said polyethylene glycol is diethylene glycol or a polyethylene glycol having a molecular weight of about 600.

6. A composition according to Claim 4 or Claim 5, wherein said composition also contains (4) from 0.25 to 1.25% by weight, based on the total weight of solidus in said composition, of an alkylene diamine of a polyalkylene polyamine.

7. A composition according to any preceding Claim, wherein said elastomer has a particle size of up to 4,000 .

8. A heat- and pressure-consolidated article comprising, in superimposed relationship, (A) a self-supporting substrate and (B) a decorative cellulosic paper sheet impregnated with a composition according to any preceding Claim.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. copolymer containing 3.5% carboxyl groups. A sharp, bright decorative panel is recovered which exhibits good crack resistance at low humidity and possesses no cracks after 20 days at 0% R.H. Examples 42--44 When the tetraethylene pentamine of Example 39 is replaced by an equivalent amount of (42) ethylene diamine, (43) diethylene triamine and (44) triethylene tetramine, substantially identical results are achieved. Example 45 To 40 parts of a 1:1.6 melamine/ formaldehyde resin syrup at 58% solids are added 4.4 parts Qf ethylene glycol. The blend is stirred to achieve a good admixture and ammonium sulfate is added as a catalyst. A laminate is then made from the resultant syrup as in Example 37. Example 46 When the procedure of Example 45 is again followed except that the ethylene glycol is replaced by 2.9 parts of a commercially available polyethylene glycol of a molecular weight of about 2,000, good results are observed. WHAT WE CLAIM IS:

1. A composition comprising a mixture of (I) an aqueous melamine/formaldehyde resin solution, (2) from 2.5% to 30.0% by weight, based on the weight of the resin solids of (1), of an elastomer comprising: (a) an ethylene/vinyl chloride copolymer containing copolymer from 0.5% to 7.0%, by weight based on the total weight of (a), of units containing amide groups or (b) a polyurethane elastomer containing from 3.0% to 10.0% by weight, based on the total weight of (b), of carboxyl groups, said elastomer having a particle size of up to 20,000 A.

9. A composition according to Claim I,

Claim 2 or Claim 4. and substantially as described in any one of the Examples herein.

10. A heat- and pressure-consolidated article according to Claim 8 and substantially as described in any one of the Examples herein.