SK280828B6 - Process for preparing modified phenolic resins to produce foam material, the use thereof - Google Patents

Abstract

The invention relates to a process for the preparation of phenol resols for foams, in which monosaccharides or disaccharides, sugar alcohol or urea-formaldehyde condensation products are added to the starting materials for resol resin preparation. The foams produced in this way are biodegradable, for example during composting.

Description

Technical field

The invention relates to modified phenol-formaldehyde foam resols of the resol type for the production of biodegradable, duroplastic phenolic resin resins.

BACKGROUND OF THE INVENTION

The use of biodegradable plastics is increasingly required. Such biodegradable plastics are disclosed, for example, in Kunststoff-Lexikon, Cari Hanser Verlag, 8th edition (1992), p. Biodegradability can be achieved by modifying thermoplastics, but biodegradable thermosets are not yet known.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide phenol-formaldehyde foams from which thermosetting thermosetting foams can be biodegradable.

SUMMARY OF THE INVENTION

According to the invention, it is surprisingly possible to modify the starting materials for the production of phenolic resins prior to condensation to the resin, i.e. to form a phenolic resin. to the phenol / formaldehyde mixture, as well as to their other components, without limiting condensation and foaming. Suitable amounts of admixture are 5 to 50% by weight with respect to phenol. The admixtures do not prevent the condensation of the resins and allow the formation of foam of the same quality as without the admixture. Foam substances with admixtures disintegrate in the wet and ingress of microorganisms.

The condensation of phenolic resins with their admixtures takes place under normal manufacturing conditions and without changing the typical characteristics of the foamed resins or the foamed products produced therefrom.

The resin feedstock of phenol and possibly cresol can be condensed in the usual amounts of the formaldehyde planned for this purpose by the addition of hot alkali, the additives according to the invention being present from the beginning. Conventional basic condensation agents such as NaOH, barium hydroxide or ammonia can be used in known amounts. After condensation of the resin, it is neutralized in the usual manner with acids and dried to a viscosity of preferably 2000 to 12 000 mPa · s ^-1 , measured at 20 ° C, under vacuum. Surprisingly, the added substances were surprisingly still partially available after the condensation of the resin.

Mono- and disaccharides, the corresponding carbohydrate alcohols, as well as urea-formaldehyde condensation products, which, in a similar way to carbohydrates, contain several -OH groups, e.g. j. low-molecular-weight, water-soluble substances with a plurality of, optionally with a large number of -OH groups.

For the production of foams, resins at room temperature are mixed with an expandable substance, with low boiling expansives such as hydrocarbons and mixtures thereof boiling between 36 and 80 ° C being preferred. Acid reinforcing agents such as toluene- or phenolsulfonic acids as well as surfactants are added.

The foaming of the resins takes place in a customary manner at temperatures from 40 to 60 [deg.] C. in a heated mold or in a double press, while at the same time stiffening occurs.

DETAILED DESCRIPTION OF THE INVENTION

A typical frothing formula is as follows:

100 parts by weight of the resin, 2 to 8 parts by weight of the surfactant mixture, up to 10 parts by weight of the expandable material, up to 15 parts by weight of the reinforcing agent and 0.5 to 2 parts by weight of the colorant.

A typical foam is characterized by the following data: solid resin content 70-84% by weight, viscosity (20 ° C, Hoeppler) 2000-10,000 mPas, water content (according to Karl Fischer) 5-20% by weight., Free phenol 4-10 % formaldehyde 0.2-3% by weight, resin reactivity 100-150 ° C.

The reactivity of the foam resin as a measure of the stiffening rate is determined by measuring the maximum temperature after the addition of a certain amount of a standard stiffener as a function of time.

For the production of substantially hydrophobic foams, surfactant mixtures are used which act hydrophobically, while hydrophilic surfactant mixtures are used for preferred cut-off foam foams. Such foams are used in particular for the production of shaped articles for the treatment of cut flowers, but also for the production of water-soaked protective containers for the transport of flowers.

The water soaking, important for this purpose, should lie around 80% of the water by the choice of surfactants, based on the volume of the foam, and the water soaking rate should be high and should not exceed a few minutes.

The foams used to stab the cut flowers in their treatment are usually colored, preferably green dyes. Surprisingly, it has been found that these foams have excellent color fastness due to the additives according to the invention.

Preferably, the surfactant mixture of nonionic surfactants and anionic surfactants in a weight ratio of 1: 5 to 5: 1. The thus prepared foaming agents for the treatment of cut flowers have a density in the range of 15 to 35 kg / ^m3.

Furthermore, it has been found that the flower-forming foams thus produced are also perfectly suited for crop-free crops of ornamental and useful plants using nutrient solutions.

In order to test the biodegradability of the described foams for cutting cut flowers, a series of experiments were carried out at the Institute for Vegetable Growing at the Technical University of Hannover. The foam was mixed in different proportions with the compost, the mixtures were placed in glass containers and 24-hour CO ₂ production was measured as a degradation rate of up to three weeks apart. The CO ₂ values initially were well above those corresponding to the compost / foam mixing ratio, indicating the degradation of duroplastic foams. The series was completed after 4 months. In flower treatment foams made from unmodified phenolic resins without additives according to the invention, no decomposition of the microorganisms was found even after 6 months of composting.

Claims (3)

PATENT CLAIMS Process for the production of modified phenolic resols for the production of foamed substances, characterized in that from 5 to 50% by weight of the mono- or disaccharide, with respect to the phenols, is added to the starting materials for the production of phenolic resins before condensation to the resin; Carbohydrate alcohol or urea-formaldehyde condensation product as modifying agent and the condensation is carried out in a basic environment. Process according to claim 1, characterized in that the modifying agent is glucose, fructose, lactose or sorbitol. Use of phenolic rhizomes produced according to one of claims 1 to 2 for the production of biodegradable foams, in particular flower-sticking foams. End of document