Impregnate with antistatic properties

Abstract

An impregnate with antistatic properties for use in laminates or for coating wood-based panels is disclosed. A resin used for impregnating and/or coating paper may include carbon-based particles, at least one compound of the general formula (I) R.sup.1.sub.aR.sup.2.sub.bSiX.sub.(4-a-b), and/or hydrolysis products thereof. X is H, OH, or a hydrolysable moiety selected from the group including halogen, alkoxy, carboxy, amino, monoalkylamino or dialkylamino, aryloxy, acyloxy, or alkylcarbonyl. R.sup.1 is an organic moiety selected from the group including alkyl, aryl, or cycloalkyl, which may be interrupted by —O— or —NH—. R.sup.1 has at least one functional group Q.sup.1 selected from a group including a hydroxy-, amino, monoalkylamino, carboxy, mercapto, alkoxy, aldehyde, acrylic, acryloxy, methacrylic, methacryloxy, cyano, isocyano or epoxide group. R.sup.2 is a non-hydrolyzable organic moiety selected from the group including alkyl, aryl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl; a is 0, 1, 2, or 3, and b is 1, 2, 3, or 4.

Claims

1. An antistatic impregnated and/or coated paper for use in laminates or for coating wood-based panels, wherein at least one resin used for impregnating and/or coating the paper consists of a formaldehyde containing resin and comprises: carbon-based particles; at least one compound having the general formula (Ia):
R.sup.1.sub.aSiX.sub.(4-a)  (Ia), and/or hydrolysis products thereof, wherein X is H, OH, or a hydrolyzable moiety selected from the group comprising halogen, alkoxy, carboxy, amino, monoalkylamino or dialkylamino, aryloxy, acyloxy, and alkylcarbonyl, wherein R.sup.1 is an organic moiety selected from the group comprising alkyl, aryl, C.sub.2-C.sub.6 alkenyl, C.sub.3-C.sub.8 cycloalkenyl, and cycloalkyl, which may be interrupted by —O— or —NH—, wherein R.sup.1 has at least one functional group Q.sub.1 selected from a group comprising a hydroxy, amino, monoalkylamino, carboxy, mercapto, alkoxy, aldehyde, acrylic, acryloxy, methacrylic, methacryloxy, cyano, isocyano and epoxy group, wherein a is 1 or 2; and at least one further compound of the general formula (II):
R.sup.3.sub.cSiX.sub.(4-c)  (II), and/or hydrolysis products thereof, wherein X has the above meaning, wherein R.sup.3 is a non-hydrolyzable organic moiety selected from the group comprising alkyl, aryl, alkenyl, alkynyl, cycloalkyl, and cycloalkenyl, and wherein c is 1, 2, or 3.

2. The antistatic impregnated and/or coated paper according to claim 1, wherein X is selected from a group comprising H, OH, fluorine, chlorine, bromine, iodine, C.sub.1-6 alkoxy, C.sub.6-10 aryloxy, C.sub.2-7 acyloxy, and C.sub.2-7 alkylcarbonyl.

3. The antistatic impregnated and/or coated paper according to claim 1, wherein R.sup.1 is selected from a group comprising C.sub.1-C.sub.30 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.3-C.sub.8 cycloalkyl, and C.sub.3-C.sub.8 cycloalkenyl.

4. The antistatic impregnated and/or coated paper according to claim 1, wherein the at least one functional group Q.sup.1 is selected from a group comprising epoxy, hydroxy, ether, acrylic, acryloxy, methacrylic, methacryloxy, amino, alkoxy, cyano, and isocyano group.

5. The antistatic impregnated and/or coated paper according to claim 1, wherein the non-hydrolyzable organic moiety R.sup.3 is selected from a group comprising C.sub.1-C.sub.15 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, and C.sub.6-C.sub.10 aryl.

6. The antistatic impregnated and/or coated paper according to claim 5, wherein the non-hydrolyzable organic moiety R.sup.3 is selected from a group comprising C.sub.1-C.sub.10 alkyl.

7. The antistatic impregnated and/or coated paper according to claim 1, wherein the paper to be impregnated and/or coated with the at least one resin is a decorative, kraft, overlay, or base paper.

8. The antistatic impregnated and/or coated paper according to claim 1, wherein the at least one resin used for impregnation and/or coating is an aqueous formaldehyde-containing resin.

9. The antistatic impregnated and/or coated paper according to claim 8, wherein the aqueous formaldehyde-containing resin is a melamine-formaldehyde resin, urea-formaldehyde resin, melamine-urea-formaldehyde resin, phenol-formaldehyde resin or mixtures thereof.

10. The antistatic impregnated and/or coated paper according to claim 1, wherein the solid content of the resin is between 50 and 75% by weight.

11. The antistatic impregnated and/or coated paper according to claim 10, wherein the solid content of the resin is between 55 and 70% by weight.

12. The antistatic impregnated and/or coated paper according to claim 11, wherein the solid content of the resin is between 60 and 65% by weight.

13. A process for producing an antistatic impregnated and/or coated paper according to claim 1, the process comprising the steps of: providing a resin suspension consisting of a formaldehyde containing resin and comprising carbon-based particles, at least one compound of the general formula (Ia), and at least one further compound of the general formula (II); providing a paper layer; impregnating the paper layer with the resin suspension and/or coating the paper layer with the resin suspension; and drying the impregnated and/or coated paper layer.

14. The process according to claim 13, wherein the paper layer is impregnated with the resin suspension in an impregnation channel.

15. A laminate comprising at least one antistatic impregnated and/or coated paper according to claim 1.

16. The laminate according to claim 15, wherein the at least one antistatic impregnated and/or coated paper is a Kraft impregnate and/or a decorative impregnate.

17. A wood-based panel comprising at least one carrier board and at least one antistatic impregnated and/or coated paper according to claim 1 arranged on at least one side of the carrier board.

18. The wood-based panel according to claim 17, wherein the at least one antistatic impregnated and/or coated paper is a decorative impregnate.

19. The antistatic impregnated and/or coated paper according to claim 1, wherein the carbon based particles are carbon nanotubes or graphene.

Description

DESCRIPTION OF THE INVENTION

Example 1: Preparation of a First Resin Suspension with Modified Carbon Particles

(1) For modification, 90 g (or 80 g) of melamine-formaldehyde resin and 8.5 g (or 17 g) of water are added, followed by 0.08 g (or 0.16 g) of para-toluenesulphonic acid. To this aqueous solution 0.7 g (or 1.4 g) of gylcidyloxypropyltriethoxysilane and 0.16 g (or 0.32 g) of ocytyltriethoxysilane are added.

(2) Then 1.5 g (or 3 g) of CNTs are dispersed in the solution using ultrasound and high shear (15 000 rpm ultraturray) and stirred at 40° C. for 30 minutes. This solution can now be processed like a normal resin system. (In parentheses are the specifications for the sample with 3% CNT in the resin)

Example 2: Preparation of a Second Resin Suspension with Modified Carbon Particles

(3) For modification, 98.5 g water is added and then 0.08 g para-toluenesulfonic acid. To this aqueous solution 0.7 g of gylcidyloxypropyltriethoxysilane and 0.16 g of ocytyltriethoxysilane are added.

(4) Subsequently, 1.5 g CNTs are dispersed in the solution using ultrasound and high shear forces (15 000 rpm ultraturray) and stirred at 40° C. for 30 minutes. This pure aqueous solution can now be dosed to melamine resin directly at the application machine.

Example 3: Production of a First Impregnate

(5) In an impregnation channel, a printed decorative paper (paper weight: 80 g/m.sup.2) is subjected to a core impregnation in the first impregnation bath. The impregnation is carried out with a standard melamine resin, which contains the usual additives (hardeners, wetting agents, defoamers, etc.) in normal quantities. The impregnating liquor had a solids content of approx. 65 wt %.

(6) To ensure that only a core impregnation was achieved, the decorative paper was sharply peeled off on both sides with a knife blade after impregnation. The resin application was approx. 80 wt % solid resin.

(7) The impregnate was dried in a floatation dryer and then coated on the back with a melamine resin in a screen unit. In addition to the usual auxiliary materials, the impregnate contained approx. 2.5% by weight carbon nanotubes from example 2. Approx. 30 g resin fl./m.sup.2 were applied.

(8) The impregnate was dried in a second air flotation dryer to a residual moisture content of approx. 6% by weight. The impregnate was cut to size and stacked.

(9) The decorative impregnate was pressed onto a large-format HDF (2.8×2.07 m, 8 mm) at approx. 200° C., 15 sec. and 40 kg/cm.sup.2 with an overlay and a backing in a KT press. Then a sample 50×50 cm was cut out of the large-format panel and conditioned for two weeks at 50% relative humidity, 23° C.

(10) Then the surface resistance was determined on the sample in accordance with DIN EN 1081: 2018. This resulted in a value of 1.0×10.sup.9Ω. A value of 5×10.sup.12Ω was found for a zero sample without carbon nanotubes

Example 4: Production of a Second Impregnate

(11) In an impregnation channel, a printed decorative paper (paper weight: 80 g/m.sup.2) is impregnated with a melamine resin in the first impregnation bath. The impregnation is carried out with a standard melamine resin in which the usual additives (hardeners, wetting agents, defoamers etc.) were contained in the normal quantities. The solids content in the resin was approx. 65 wt %. In addition, the resin contained approx. 2.5% by weight carbon nanotubes from example 2.

(12) After the squeeze rolls, approx. 140 g resin fl./m.sup.2 were still contained in the decor paper. The impregnate was dried in an air flotation dryer to a residual moisture content of approx. 6% by weight. The resin application rate was approx. 110% by weight. The impregnate was then cut to size and stacked.

(13) The decorative impregnate was pressed onto a large-format HDF (2.8×2.07 m, 8 mm) at approx. 200° C., 15 sec. and 40 kg/cm.sup.2 with an overlay and a backing in a KT press. Then a sample 50×50 cm was cut out of the large-format panel and conditioned for two weeks at 50% relative humidity, 23° C.

(14) Then the surface resistance was determined on the sample in accordance with DIN EN 1081: 2018. This resulted in a value of 8.0×10.sup.8Ω. A value of 5×10.sup.12Ω was found for a zero sample without carbon nanotubes.

Example 5: Production of a Third Impregnate

(15) A soda kraft paper (paper weight: 150 g/m.sup.2), which is to serve as the core layer for a CPL continuous produced laminate), is subjected to impregnation in an impregnation channel. An impregnating resin consisting of approx. 65% by weight of melamine resin and 35% by weight of a phenolic resin is placed in an impregnation trough. The two resins had a solids content of approx. 65 wt %. The total solids content after addition of the auxiliary materials and water was approx. 60% by weight. The resin mixture contained the usual additives (hardeners, wetting agents, defoamers, etc.) in normal quantities. In addition, the resin contained approx. 2.5 wt % carbon nanotubes from example 2.

(16) The soda kraft paper was impregnated with the impregnating resin in the impregnating trough. After the squeeze rolls, the soda kraft paper still contained approx. 215 g resin fl./m.sup.2. The impregnate was dried in an air flotation dryer to a residual moisture content of approx. 6% by weight. The resin application rate was approx. 85 wt %. The impregnate was then rolled up.

(17) The force impregnate was pressed with an overlay impregnate, a decorative impregnate and a pergament in a CPL press to form a thin laminate (T=approx. 200° C., v=15 m/min and 60 kg/cm.sup.2). Then a sample 50×50 cm was cut out of the laminate and conditioned for two weeks at 50% relative humidity, 23° C.

(18) Then the surface resistance was determined on the sample in accordance with DIN EN 1081: 2018. This resulted in a value of 6.0×10.sup.8Ω. A value of 9×10.sup.11Ω was found for a zero sample without carbon nanotubes.