FI76104C - Surface coating procedure for wood and wood combination board - Google Patents

Description

76104

This invention relates to a coating method for protecting the surface of a particle board, plywood or wood or wood composite board against wear, shocks, water absorption or various chemical and physical stresses. The method uses various mixtures of thermosets by thermosetting them to the surface of the sheet materials with a hot pressure press.

Various coating methods are known for surface protection of wood panels, in which either the finished plastic laminate board is glued to the surface or absorbent paper pre-impregnated with plastic resin or a glass mat is hot pressed to cure the resin (Film-Forming Compositions, Parts I-III, Raymond R. Myers and JS Long 1972, Marcel Dekker, Inc., New York, "Modern Oberflächenbeschichtigung", Soine, H., Holz-technologie 18 (1977) 2, pp. 100-104; "Economic feasibility of synthetic fiber reinforced laminated veneer lumber", Laufenberg , TL, Rowlands, EE, and Krueger, GP, Forest Prod. J. 34 (1984) 4, pp. 15-22).

It is also known to treat the plywood surface with mixtures of temporal phenolic resins, in which organic fillers are used as fillers: wood flour, coconut shell flour, starch powder, etc. Inorganic fillers are known as chalk flour and barium sulphate powder. Only organic reactive polyphenol powders, such as kebrazo and certain tannins, and paraformaldehyde have been used as curing accelerators in these mixtures. The catalytic effect of metal ions has been known on the adhesive resin side, but has been believed to be effective only in the pH range of 2.5-7, because on the alkaline side the OH ion concentration determines the reaction rate (Chemistry and Application of Phenolic Resins. A. Knop and W. Scheib, 1979, 1979, Springer-Verlag, Berlin; Wood Adhesives Chemistry and Technology, A. Pizzi, 1983, Marcel Dekker, Inc., New York). Thus, on the side of the alkaline coating resins 35, they have not been used because it is believed that they do not obtain a sufficient drying and curing rate.

2 76104 "

Metal catalysts have been found to form a variety; chelate complexes with phenolic resin. Catalytic effect based on the rate of exchange of metal ions, so salts of weaker acids have been believed to work more efficiently 5 than salts of strong mineral acids. Metal ion catalysis is based on the so-called ortho-ortho directed effect, and thus e.g. sulphate ion is believed to slow down the catalysis due to its meta-control and circumferential deactivation.

In surface resin, the resin mixture 10 without a carrier phase must be pressed with a wire or similar pattern mesh. This prevents stresses in the resin coating during the curing step, which may later cause cracks. The wire pattern as a coating also serves as a friction surface in floorboard use.

15 The phenolic resin, which hardens as a thin layer, forms a thin layer of plastic wood with the plywood, which also prevents the surface resin from breaking due to the water-swelling and thermal expansion of the plywood below.

In current surface resin processes, alkaline phenolic resins darken unevenly under the influence of heat. This causes color variation as the boards coated on the surfaces stand hot in the stack. As a result, black surfaces have been satisfactory, or surfaces have had to be painted later, which may have been difficult due to the release agents contained in the coating resins.

The phenolic resin mixtures used have contained mainly organic substances: fillers such as wood flour and coconut shell flour, thickeners such as starch and hardeners such as kebratso yra. polyphenols and paraformaldehyde. This has caused the strength of the coating to be not very high. In addition, the organic fillers contain capillaries, so water is absorbed quite easily through the coating. In addition, the cured surface is transparent, so that although a black color pigment has been used, the grain patterns, knots, and other irregularities of the veneer of the plywood 35 will be visible through the coating.

761 04 3

After application of the current surface resin compositions and oven drying, the resin is still so pressure sensitive and the onset of curing reaction continues when the hot sheets are stacked that the sheets tend to stick together, making it difficult to remove them for insertion into a hot press. To alleviate this phenomenon, a paraffin emulsion has been added to the resin mixture, but this has also only partially alleviated the matter.

A method 10 according to the claims and a mixture for use therein have now been invented, by means of which the above-mentioned disadvantages can be prevented. In one embodiment of the invention, all organic fillers in the normal phenolic resin mixture have been replaced by inorganic mineral powders and inorganic metal compounds have been used as catalysts instead of organic polyphenolic hardeners and paraformaldehyde. In addition, the surface is made opaque with a reflective TiO 2 pigment or its substitute. Chalk flour and BaSOjj et al. Powders, for example, have been studied as mineral powders replacing organic fillers. Wollastonite has given the best results as a Pill that increases the strength of 20. Of the metal catalysts, bi- and triva- have given the best results. . . . 2+ 2+.

iron oxides and salts of Zn and Mg ions. As the alkaline phenolic resin, a lower alkali form with a pH of about 10 has been used instead of the normal plywood adhesive resin. The inorganic metal salt catalysts studied in the invention achieve a better degree of drying and curing than polyphenols and formaldehyde. Conventional organic accelerators also rapidly precipitate the mixture, thus shortening its service life.

In addition to inorganic fillers, some organic substances can be used, such as to adjust the viscosity of starch. The amount of mineral powders based on the total weight of the mixture can vary between 20-50% depending on how abrasion resistant the coating is desired. The amount of the inorganic salt hardener may vary between 10-20% based on the dry weight of the phenolic resin. The faster the hardener is, of course, the faster the hardener, the higher the service life of the mixture. When ZnSO 2 x 7H 2 O is used, 12% in aqueous solution and 17% in solid addition are the recommended amounts. If the hardener is added as a solid, precipitation of the mixture over time may interfere with its use. It is also possible to use hardener solutions with several salts, e.g. mixed solutions of Zn sulphate, Mg sulphate and Zn acetate.

In another embodiment of the invention, white or colored coatings have been developed which do not change color upon stacking of the sheets after oven drying. This color fastness is achieved by the phenolic resin mixture by lowering the pH of the phenolic resin mixture below 8.6 or by a suitable melamine-resin-phenolic resin mixture, where the service life and applicability of the melamine resin on the roll is improved by a suitable low-alkali phenolic resin additive.

The penol-resin mixture is made to pre-cure in the drying ovens sufficiently so that the surfaces of the various sheets no longer adhere hot to each other when standing on the stack, so that they can be hot-pressed, e.g. with a steel wire mesh in a sheet press. This is accomplished with suitable bivalent metal cations.

The color change in phenolic resin mixtures due to heat is due to the oxidation of phenolic compounds to methoxyquinoid compounds, which in certain combinations are darker in color than the original phenolic resin combinations. By igniting the pH of the phenolic resin mixture below 8.6 or by using phenolic resin-melamine resin mixtures, etc., the color change reaction can be prevented.

Purely such water-soluble wood glue phenolic resins are not available and novolak resins are thermoplastic, making it difficult to use them for this purpose.

However, certain ammonia, amine and Ba (OH) 2-catalyzed phenolic resins can be stabilized and their pH adjusted to 7-8 with certain amino resin additives. These phenolic resins do not have sufficient adhesive forces, so they are unable to bind filler powders and wood material.

However, when so much alkaline wood-adhesive phenolic resin is added to the batch that the pH of the mixture remains below 8.6, the phenolic resin is obtained sufficiently to bind the mineral powders. The addition of an alkaline wood glue resin to, for example, glass-la-phenol resin also accelerates the maturation of the mixture in the curing step. Other additives in the resin composition are mineral-filled filler powders.

Urea-neutralized glass wool phenolic resin can also be added to ordinary urea-melamine wood glue resin. This improves the behavior of the latter resin on the resin spreading rollers. Ordinary resin is easily adhered to the grooves of Vals-10 sin and washing is difficult. This adhesion is reduced by this mixing of the resins. The urea-melamine resin of the mixture cures in hot pressing with the addition of acid salts of salmia and the like, and the phenolic resin part in turn with bivalent metal ions. The other fillers 15 are mineral powders. If a pleasant brown color is desired for the coating, it is obtained with added iron oxide powders which at the same time act as curing catalysts for the mixture. If another color is desired for the coating, various pigments can be used and pheno- 2+ p + as hardeners.

20 for meat resins e.g. salts of Zn or Mg ions. The catalyst combinations described above cause the amino resin-phenol resin mixture to cure faster than the phenol-resin mixture alone. This is an advantage if the power of the drying ovens used does not want to be sufficient for the surface-stacking of the dry-surface surface resin before hot pressing after the application of the resin mixture.

According to the invention, a porous wood board can be protected by hot pressing a suitable amount of thermosetting resin mixture onto the surface, whereby a layer with intermediate properties remains between the actual board and the resin laminate-50 tip. This intermediate layer compensates, for example, for the different movements of the base plate and the surface layer due to thermal expansion and swelling. In addition, this intermediate layer gives new properties to the entire coated board, improving e.g.

35 abrasion resistance measured by the DIN 53799 test for chipboard or plywood veneer and rolling resistance measured by the SS 923508 test.

6 761 04 According to the present invention, a surface layer resistant to weather conditions is available for particle board and other porous wood and composite boards, which also corresponds to products known as plastic wood as an intermediate layer according to the invention in terms of wear and rolling resistance.

The resin blends described above have been tried for this purpose with good success. The coated chipboard has been tested with a rolling tester according to SS 923508 with a load of 3000 N, and it has been found that the coated chipboard withstands the rolling test better than a similarly coated plywood. This is because the chipboard is more uniform in different directions than the plywood, and in addition, the chipboard has transverse pores which absorb the hot-pressed resin more easily than the pores in the surface plane 15 of the plywood. If the chipboard itself contains more adhesive resin, the rolling resistance of such a chipboard is improved. However, the density of the sheet has its optimum value, and the resin mixture cannot be easily compressed on an excessively dense surface. However, the types of board-20 such as cement chipboard can also be coated with the mixtures.

Such strong wear- and rolling-resistant boards have use, for example, as a floorboard in both indoor and outdoor conditions. The types of panels coated according to the invention are also suitable in various hall structures, animal shelters, ships, etc. According to the invention.

However, continuous contact with liquid water may, over time, damage at least the chipboard, so in such conditions the edges of the board should be carefully protected. If you want to use the coated-30 and sheets, e.g. in wall structures, the hot pressing can be performed using smooth press sheets, or if desired with different patterned coats. In the manufacture of a floorboard, the boards are pressed with a plastic or steel wire mesh to obtain a friction effect.

7,76104; )

Example 1

Exter 401 ® 300 po (parts by weight)

Wollastonite 150

TiO2 6 [5 Carbon black 3

ZnSOjj x 7 H20 20

Water 30

The Exter 401 used in the mixture is a special purpose plywood adhesive resin with a pH of about 10.8, a viscosity of about 170 mPas and a dry matter content of about 40%.

The viscosity of the mixture is about 1500 mPas at 25 ° C and rises to about three times within 3 days. With a little water, the mixture is made useful again. The resin mixture can be applied, for example, by a roller to the surface of a wood board at 100-1550 g / m 2 and dried by blow drying at 110-120 ° C.

after which a second layer of stud can be applied. j ί resin mixture. After the second drying, a thin layer of molten paraffin can be applied to the surface, and the sheets can be> stacked on top of each other to await the actual hot pressing, which is done using steel or plastic wire mesh at a temperature of 130-140 ° C. The coating is then so mature that it is resistant to dilute NaOH solution and other chemicals.

The abrasion resistance of the coating, measured according to DIN 53799, is about 1000 revolutions of wear, which is about two to 25 times the value achieved when using organic fillers and hardeners. In addition, the water absorption of the coating is reduced. 98% of inorganic fillers and the like.

Example 2 30 Exter 401® 300 po

Wollastonite 130

TiO2 6

Carbon black 3

ZnSOjj x 7 H20 20 35 Mobilcer 60 ® 15

Water 40 8 76104 When using paraffin emulsion (Mobil-cer 60) in the adhesive mixture, it is not necessary to apply molten paraffin to the surface after oven drying, but it needs good cooling when stacking the boards to wait for hot pressing. If the cooling is not sufficient, the plates will stick to each other while standing on the stack. Et al. the amount of wollastonite in the mixture has been slightly reduced, and thus the abrasion resistance value is about 800 revolutions. 90% of inorganic fillers and the like.

10 Example 3

Exter K® 300 po

Wollastonite 130

TiO2 6

Carbon black 3 15 ZnSOjj x 7 H20 20

Pe203 10

Mobilcer 60 ® 20

Exter K is an impregnation phenolic resin with a pH of 9.5 and ka. 42.8%.

20 Oven drying as in Example 2 gives yo. a relatively dry product with a mixture and a coating mature in hot pressing at 130-140 ° C. 88% of fillers and the like are inorganic.

Example 4 25 Penorex 615 ® 2200 po

Exter 401® 380

Wollastonite 1000

Chalk flour 1000

TiO 2 75 30 Fe 2 O 3 60

Fri3 ° 4 * 5

Mobilcer 60 ® 100 BX starch 70

Eo. Penorex 615 contains glass wool phenolic resin, low alkali phenolic resin used in 35 Exter 401 plywood gluing and wollastonite fibrous Ca silicate powder.

Of the total amount of phenolic resins in the mixture, 15% of Exter 401 9 76104 resins have a pH of about 8.6. If the proportion of wood glue resin is increased, the proportion of wollastonite and chalk flour in the fillers can be increased, but then the above-mentioned variation in the color of the coating begins to occur, the higher the higher the pH. 93% of inorganic fillers and the like are inorganic.

Example 5

Fenorex 615 ® 2300 po

Exter 40 ^ β) 300 10 Wollastonite 1500;

Ti02 70 *

Carbon black 10

Fe 2 O ^ 60

ZnSOjj x 7 H20 150 15 Mobilcer 60 ® 100

The viscosity of the mixture can be adjusted upwards by the addition of starch and reduced by the addition of water. A suitable viscosity is 1500-2000 mPas for roller application. The addition of water prolongs the drying time. The chalk flour has been omitted 20 in the mixture, replacing it with wollastonite. In this case, the surface strength is increased. Care must be taken with the addition of acidic Zn sulphate, as the Exter * 101 resin precipitates in the mixture as the pH drops to around 7. 94% of fillers and the like are inorganic.

25 Example 6

Melurex V ® M00 po

Fenorex 615 ® 1300

Wollastonite 700

Chalk flour 700 30 Ti02 50

Fe 2 O 3 35 35

Mobilcer 60 ® 100 NHjjCl (25%) 100

35 BX starch HO

Melurex V is a urea-melamine resin used in plywood gluing. The mixture is easily applied by roller and its viscosity of 761 04 10 is maintained for 3 days in the range 1500-2000 mPas.

Et al. the abrasion impurity wear value of the coating of about 300 g / m 2 is about 700 revolutions. 92% of non-organic fillers and other substances.

5 Example 7

Test resin 230 po

Wollastonite 150

TiO2 15

Dispers Brown 1 10 Zn (CH 3 COO) 2 (25%) 30

ZnSO 4 x 7 HpO (25%) 20

Mobilcer 60 © 20

Night. the test resin is about 48% aqueous phenolic resin solution with a pH of 8.6. The hardeners Zn sulfate and Zn acetate are each 25 5S aqueous solutions. Et al. the mixture gives a light brown coating with an abrasion blast-snow value of about 600 revolutions.

Et al. in light resin coatings, when phenolic resins alone are used, the upper pH limit can be considered to be 8.6, above min-20, color change reactions begin to occur.

When a melamine or urea melamine resin is used among the phenolic resin, the mixing ratio with certain neutral glass-la-phenolic resins is free. The amount of the amino resin hardener, e.g. salmia, in the mixture can be 7-15% and the amount of the bivalent salt of the phenolic resin-25 hardener 10-20%. dry weight of resins. Of the fillers and the like, 91% are inorganic.

Example 8

Melurex V ® 110 per 30 Fenorex 615 ® 110

Wollastonite 100

Chalk flour 100

TiO2 6

Fe 2 O 3 4.5 35 Fe 3 O 4 4.5

Mobilcer 60 ® 10 NH 4 Cl (25%) 10 11 76104

When used on the chipboard surface, the cure rate of the mixture is higher than on the plywood surface, due to the fact that e.g. the urea-melamine resin bonded chipboard contains free formaldehyde, which forms hexamine 5 with NH 3 Clin, releasing HCl, which acts as a hardener for amine components.

As the surface resin of the phenolic resin bonded chipboard, the resin blends of Examples 1-5 are preferable. 96% of inorganic fillers and the like.

10 Example 9

Melurex V® 1100 po

Fenorex 615 ® 1100

Wollastonite 1000

Chalk flour 1000 15 TiO2 60 i

Fe 2 O 3 to 5 |

Fe 2 O 3 45 NH 4 Cl (25%) 120

Water 50 20 The plywood and chipboard were surface resinized with the mixture as described above. After the second surface resin drying oven treatment, a thin layer of normal commercially available molten paraffin was applied to the surface, and such coated sheets were stacked on top of each other while holding them at 25,100 ° C. After about 2 hours, the plates were easily detached from each other and hot pressed in the normal way using a wire mesh. The quality of the finished surface obtained was excellent. Depending on the hot pressing time at 150 ° C, the surface was either completely free of paraffin or partially or completely covered with a layer of paraffin. Ko. the procedure can be applied in many different ways, so the invention is not limited to the example of et al.

Example 10 35 was done otherwise as in Examples 1-8 except that the paraffin emulsion was omitted from the mixture and molten paraffin was applied to the surface instead, and the procedure was as described in Example 9 of 76104 12. The result was excellent.

Example 11

Resol <B> test resin 230 po j 5 Wollastonite 130

TiO2 15

Fe 2 O-j 6

Fe ^ 5 k2co3 10 i 10 Mobilcer 72 ® 20 j

The resole test resin is a special phenolic resin with a pH of about 9.5 and an alkalinity of about 1.5% - Fe-oxides and potash act as hardeners. Et al. the mixture gives a dark brown coating with an abrasion blast wear value of about 1000 to 15 revolutions. The pH of the mixture is therefore high (about 10) so that color changes begin to occur under the influence of heat. Enough! however, the dark brown mixture, when well cooled after oven drying and hot pressing, gives a satisfactorily smooth surface. 89% of fillers and the like are inorganic.

Claims (10)

A method for coating a clamping plate, vanes and other wood or wood combination sheet, in which on the surface of the skiing is spread a resin mixture containing both filling and extruding and curing agent, and which plate is then cured, characterized in that the wafer surface spreads a phenolic resin composition of phenolic resin or a mixture of phenolic resin and amino resin as well as inorganic salts or curing agent inorganic salts or oxides in an amount of at least 88% by weight of the filler, extender and curing agent. Process according to Claim 1, characterized in that a phenolic resin mixture is used, in which no curing catalyst bi- and / or trivalent inorganic salts or oxides is used. Process according to claim 2, characterized in that a phenolic resin is used, which includes as a curing catalyst a site of a bivalent metal ion and a strong mineral acid. 20 4. A process according to any one of claims 1-3, characterized in that a phenolic resin composition is used which includes a mixture of phenolic resin and amino resin and a normal amino resin curing agent. 5. A process according to any one of claims 1-4, characterized in that a phenolic resin composition is used in which the filler is wollastonite. 6. A method according to any of claims 1-5, characterized in that a phenolic resin composition is used which includes a surface covering producing inorganic pigment material such as titanium oxide. Process according to any of claims 1-6, characterized in that a phenolic resin composition is used, the pH of which is high 8.6. 8. A process according to any one of claims 1-7, characterized in that a phenolic resin composition is used, which comprises glass wool phenol resin and low alkaline wood-lymphol resin. Process according to any one of claims 1-7, characterized in that the phenolic resin composition is dispersed in