CS240372B1 - Binding agent for laminated plastics production - Google Patents

Abstract

It is used to produce laminated materials based on phenol-formaldehyde resins. The binder is formed by condensate dropping in the purification of 2,6'-xylenol with formaldehyde or paraformaldehyde, or a solution thereof in solvents.

Description

The invention relates to binders for the production of laminated materials.

For the production of laminated materials, binders based on phenol-formaldehyde resins are used, which are produced by condensation of phenols with formaldehyde.

It has now been found that an excellent binder is the condensate that falls off during 2,6-xylenol purification.

The present invention relates to a binder for the production of laminated materials based on phenol-formaldehyde resins comprising 20 to 100% by weight of a mixture of linear oligomers of the condensation products of phenol, cresols, and xylenols with formaldehyde. 80 DEG C. and up to 80% by weight of alcohols, ketones, esters, aromatics, chlorinated hydrocarbons or mixtures thereof, based on the total weight of the binder.

It is known that the source of 2,6-xylenol is a phenol methylation reaction mixture containing predominantly methylphenols (o-, m- and p-cresols). To a lesser extent, other phenol methylation products are irrelevant from a quantitative point of view. Depending on the phenol methylation reaction conditions, the reaction mixture contains a different ratio of o-cresol and 2,6-xylenol, depending on whether the major methylation product is to be o-cresol or 2,6-xylenol. After the bulk of the o-cresol has been distilled off, 2,6-xylenol remains the major and most important component of the remainder of the reaction mixture. Of the other methyl derivatives of phenol, 90-95% of impurities form separate o-, m- and β-cresols.

From this mixture, 2,6-xylenol was isolated mainly by physical methods such as rectification, crystallization, resp. fractional crystallization or a combination thereof. All these processes are characterized by being very energy intensive, time consuming, requiring complex and costly equipment, and operating with large recycling rates.

Recently, very advantageous chemical refining processes for crude xylenols have been protected by copyright certificates. These methods are based on the fact that the by-products accompanying 2,6-xylenol, phenol derivatives having at least one free o-position relative to the phenolic OH group, can be practically removed by heating this mixture with paraformaldehyde, aqueous formaldehyde solution or release agents. formaldehyde in the presence of catalysts ensuring the condensation of phenol with formaldehyde predominantly into the o-position.

The condensation reaction product is a substantially linear low molecular weight condensate of phenol with formaldehyde, readily fusible usually between 50 and 80 ° C and soluble in a variety of organic solvents, particularly alcohols such as methanol, ethanol, cyclohexanol, cyclic and aliphatic ketones such as ethylmethylketone and diethylketone esters such as methyl formate, ethyl formate, ethyl acetate, methyl acetate, aromatic hydrocarbons such as benzene, toluene, xylene, chlorinated hydrocarbons such as chlorobenzene, chloroform, trichlorethylene and mixtures thereof. The property of this waste product can be advantageously used in the manufacture of laminated materials, in particular of paper, fabric and wood veneer. In addition to the advantageous mechanical properties, the laminates prepared from this waste material are characterized by high resistance to moisture, molds and bacteria as binders. The waste condensate impregnation can be carried out in the form of a solution, preferably in alcohol or a melt, for example by means of mopping, dipping in the melt, or by dusting the condensed condensate and pressing the individual layers.

Laminates prepared with this condensate as binders are very resistant to mechanical and weathering. The waste condensate solutions and the melt can be dyed in any desired manner, with a number of organic dyes and inorganic additives such as clays. Of course, the use of clays loses the advantage of coating transparency. If a condensate solution is to be used for lamination, it is advantageous to work with higher concentrations of condensate in the solution, i.e. at least 30 to 40% by weight, but solutions with a content of 60 to 80% by weight are optimal for this purpose. This means that the solvent must be evaporated before pressing the individual layers. However, it is also possible to process dilute solutions, in which case it is necessary to apply the solution several times to obtain a sufficiently high layer.

The great importance of waste recovery lies in the fact that the entire chemical refining of xylenol takes on the character of waste-free technology. A further advantage of this application is that the product can be used either in the form of a powder, a melt or a solution, and ethanol can be used as a solvent whose toxicity is insignificant. The low melting point of the waste condensate allows undemanding powder processing. The high flow index ensures perfect absorption into the porous materials from which the laminate is made and thus high mechanical cohesion.

Processes in which the condensate is applied to the individual sheets to be pressed by a combination technique by spraying and immediately dusting the previously dried paint are very advantageous. This application method does not require high volumes of solvents and it is easier to achieve high condensate layers without leaking out of the binder layer.

The following examples illustrate the invention. The percentages in the examples are by weight.

He did

500 g of 2,6-xylenol were refined as described in AO No. 231,085, Example 1.

The xylenol used for refining contained 20.2 percent of other phenol methyl derivatives.

After the purification process of pure xylene is described, the residue in a 158 g reboiler was dissolved in 70 grams of etanil. The resulting viscous solution was impregnated with 100 mm by 100 mm strips of cotton fabric at 35 ° C, and the individual sheets were dried at 55 ^° C. double spoon-shaped tear-off bodies having a width of 6 mm at the narrowest part. The exact height of the bodies was measured before the tear test for each body separately (Table 1).

The tear test was carried out on 10 bodies immediately after their preparation and on 10 bodies after 10 hours soaking in a 30 ° C water bath. The measured values are compared with the values obtained during tearing of the base material. The results show that lamination significantly increases strength and is little affected by long-term exposure to water.

T a b u 1 k a 1

Result of tear tests Body tensile strength

After exposure to water No dipping

MPa MPa base material laminated material in the form of bodies

Example 2

By the method indicated in the author's certificates according to Table 2, line 2, dealing with chemical refining of xylenol, xylenol containing 6.4% of other alkylated phenol derivatives was refined. The refining residues were used in the form of melt or solutions to produce laminates from a variety of materials. The laminates produced 25.4 31.3

43.1 45.0 bena tear test pieces. The production of both the laminate and the bodies was carried out as described in Example 1. The concentration of the prepared solutions is shown in Table 2. If the laminate was produced from the melt, this change is shown in the table. Tear tests were performed according to Example 1. The results are shown in Table 2.

Table 2

Line

Importance

9a

11 12 13

Try*

Refining carried out according to

Distillation residue

Condensate solution for lamination

Method of applying condensate Method of applying condensate Laminated material Tensile strength of laminate MPa

Tensile strength of base material MPa

AO

Example

Weight xylenoiu g Softening point ° C Condensate weight g Solvents g Solvent from melt solution after soaking without dipping

1. 1 2 3 2. 232 834 235 679 232 870 3. 3 13 4 4. 96 96 92.4 5. 72 85 73 6. 16 24 24 7. 160 24 90 8. ethanol ethanol ethanol 9. dipping acetone (1: 1) spraying Benzene (36: 64) 9a dipping 10. having fun. fabric having fun. fabric paper 11. 43.1 41.2 6.9 12. 44.1 44.1 8.8 13. 31.3 31.3 3.9 Comment: lj Default quantity raw xylenols for all tests it was 1000 g. Ending-

traces have been adjusted in proportion to the components used in the cited example of that copyright certificate.

4 5 6 7 235 607 235 608 236 128 230 842 1 5 7 4 96.2 93.8 93.1 299 69 85 80 77 24 10 5 100 ALIGN! 90 100 ALIGN! 100 ALIGN! 100 ALIGN! toluene (64:36) methanol ethanol ethanol methanol painting + + dusting dipping šopování dipping paper oak foil oak foil paper 6.9 39.2 31.3 5.9 8.8 54.9 40.2 7.8 3.9 27.4 27.4 3.9

2) Softening temperature was determined using the ring-ball method described in the monograph Jiří Helm "Testing of Oil and Their Products" SNTL, Prague 1957, p. 118; according to CSN 65 7060.

3) Average of 6 measurements (lines 11 and 12).

Claims (1)

SUBJECT Binder for the manufacture of laminated materials based on phenol-formaldehyde resins, characterized in that it consists of 20 to 100% by weight of a mixture of linear oligomers of the condensation products of phenol, cresols and xylenols with formaldehyde, leaving at INVENTION purification of 2,6-xylenol with formaldehyde or paraformaldehyde with a softening point of 50-80 ° C and up to 80% by weight of alcohols, ketones, esters, aromatics, chlorinated hydrocarbons or mixtures thereof, based on the total weight of the binder.