DE102012015539B4 - Foam material and use thereof - Google Patents

Abstract

Foam material obtained by foaming the constituents of the foam material in the presence of a foaming or blowing agent and then curing by drying, comprising: at least 50% by weight, based on the total weight of the foam material, of paper dust resulting from the waste paper recycling waste product, the waste product being a very small amount Fiber content has, • 2-5 weight percent, based on the total weight of the foam material, carboxymethylcellulose as a natural, starch-free binder.

Description

The present invention relates to a foam material and its use as an insulating board.

Increased efforts to effectively isolate housing have created a growing demand for suitable insulation materials. On the market, among other things, petrochemical products that are competitively priced and mass-produced are offered as insulation boards. For example, styrofoam is used here. Chemically, polystyrene is an expanded polystyrene (EPS), which is formed by polymerization of the monomer styrene. In addition to the recurring discussion about the dangers of styrene and its high fire load, the economic efficiency of petrochemical polymer materials is currently deteriorating. With rising oil and energy prices, plastic prices have risen sharply in recent years.

Another insulating material is specially treated mineral fibers. In addition to the problem of the availability of artificial mineral fibers (KMF) has been arguing for some time about the harmful potential of the fibers. Despite the multitude of experimental and epidemiological investigations, no definitive conclusions regarding this topic are possible. There is a great and urgent need for alternative materials in view of the great economic significance of the fiber problem, the sometimes very controversial discussions and the unclear scientific data on the assessment of the possible carcinogenicity of individual artificial mineral fiber types, especially since it is known that an increased exposure of biopersistent fibers should be avoided ,

In addition to the conventional petrochemical or mineral products, there are some efforts to use cellulose as a base material for the construction sector. Especially in the production of plate materials here but starchy or petrochemical binders are used. The starchy binders have the disadvantage that the plate material produced very easily absorbs water and the structure is irreversibly damaged. The disadvantage of petrochemical binders is mainly to be seen in the fact that a later recycling or composting of the building material is impossible.

In DE 34 201 95 C2 discloses a method for producing insulating materials, wherein a raw material of waste paper or cardboard with a binder having a high starch content, mixed and then foamed.

DE 40 088 62 C1 relates to a process for the production of paper foam from waste paper or cardboard, in which this starting material is mixed with starch, compressed in an extruder and expanded or foamed by temperature and pressure drop.

WO 2010/083548 A1 relates to a foam element containing, besides cellulose, polyurethane, polyethylene, polystyrene, polycarbonate, PVC, silicone, PMMA or rubber foam.

The DE 195 46 296 A1 describes a method for the definition of various properties of foam bodies from cellulosic materials and foamed body produced according to the method.

The DE 42 11 013 A1 describes a residue granulate and process for its preparation.

In the DE 42 18 549 C1 An insulation material based on used raw materials and their use as well as processes for its production are disclosed.

It is therefore the object of the present invention to provide a foam material which overcomes the disadvantages of the prior art. In particular, a foam material is to be provided which is recyclable and / or compostable and at the same time has a low weight, good thermal insulation properties and high mechanical stability and whose properties, depending on the intended use, can be influenced in a simple manner.

This object is solved by the subject matter of the independent claims. Preferred embodiments will be apparent from the dependent claims. Described herein is a foam material comprising cellulose, at least one natural, starch-free binder, and optionally at least one aggregate, the foam material having a cellulose content of at least 50 percent by weight based on the total weight of the foam material.

As starting material for the cellulose in the cellulose foam, it is possible in principle to use any material consisting essentially of cellulose, in particular cardboard, paper, in particular recovered paper, predominantly cellulose material or paper dust. Paper dust, which is obtained as waste product in waste paper recycling and has a very low fiber content, is provided in the starting material according to the invention.

Particularly advantageously, the foam material according to the invention in the form of plates, such as insulation boards, can be used. Likewise, however, any alternative use may be provided, for example, the production of pellets of the foam material according to the invention for a bed, so for introducing the pellets as bulk material in a cavity for insulation.

The foam material can generally be made in any manner known in the art. The preparation according to the invention is characterized in that the components of the foam material are mixed together with a foaming agent and / or blowing agent, which then causes the foaming in a foaming step. In particular, water, surfactants such as sodium lauryl sulfate or carbonate compounds, for example sodium bicarbonate, can be used as the foaming agent and / or propellant, the foaming in these cases being achieved by heating, for example in an oven, by microwave irradiation or by mechanical input of energy, for example stirring , The foaming step is followed by a drying step in which the resulting foam is cured by suitable treatment, for example by heating.

The natural, starch-free binder according to the invention is carboxymethylcellulose.

For the purposes of the present disclosure, a binder is to be understood as meaning a substance in which the cellulose and possibly also added further substances are substantially homogeneously distributed.

The natural binder according to the present disclosure is a naturally occurring material whose properties permit recycling and / or composting of the binder.

As starch-free binders are to be understood that contain neither starch nor their derivatives, such as ethers, phosphates, etc.

The natural, starch-free binder must be present in the foam material at least in such a proportion that cohesion of the other constituents is ensured, in particular the mechanical properties of the foam are retained.

The proportion of carboxymethylcellulose in the foam material is according to the invention 2-5 weight percent, preferably 3 weight percent, based on the total weight of the foam material.

It is preferably provided that the additive is a fungicide, water repellent or flame retardant.

A fungicide here is to be understood as meaning a chemical or biological active substance which kills fungi or their spores or prevents their growth for the duration of their activity.

In this case, it is preferably provided that the fungicide is a base, preferably a metal hydroxide, lime, borate or a copper salt, in particular copper sulfate.

In the case where a base is used as the fungicide, it should be used in accordance with the invention in a concentration and / or strength that will increase the pH of the material to more than 8. The group of the fungicides of the invention is in no way limited to those mentioned above. According to the invention, any common fungicide can be used.

A hydrophobizing agent in the context of the present invention is a substance or substance mixture whose presence in the foam material leads to a water-repellent surface behavior of the foam. Accordingly, by adding a hydrophobing agent, for example, a building material can be obtained which has a protective effect against the ingress of moisture.

It is preferably provided that the hydrophobing agent is a siliconate, siloxane, silicone oil or water glass.

Flame retardants in the context of the present invention are those substances which limit, slow down or prevent the spread of fires, in particular reduce the combustibility of the foam material.

It is preferred that the flame retardant is a borate, aluminum hydroxide, magnesium hydroxide, ammonium polyphosphate, sodium sulfate, a compound from the group of alums or ammonium sulfate.

The cellulose is particularly preferably paper residue, high gloss paper and / or cardboard, preferably paper dust.

It is also preferable that the foam material has pores of a diameter in a range of 1 μm-20 mm, preferably 100 μm-2 mm.

For the purposes of the present invention, pores are to be understood as meaning air or gas inclusions which arise during the foaming of the material. These pores do not necessarily have a spherical shape. Any other possible form is conceivable.

The object is likewise achieved by the use of the foam material according to the invention as an insulating board, in particular as a lightweight board.

Surprisingly, it has been found that the foam material according to the invention combines recyclability and / or compostability of the foam with a low weight, good thermal insulation properties and a simultaneous high mechanical stability. Furthermore, it has surprisingly been found that the properties of the foam material according to the invention can be adjusted in a simple manner by the addition of suitable substances depending on the intended use.

Further features and advantages of the foam material according to the invention and its use will become apparent from the following detailed description of exemplary embodiments in conjunction with the figures, wherein

1 is a photograph of a paper plate according to the invention ;,

2 is a photograph of a foam material according to the invention comprising a hydrophobizing agent and to which a drop of water has been applied; and

3 is a photograph of a foam material according to the invention containing a flame retardant and exposed to open flame.

Examples

All processes for producing the foam material according to the invention have in common that the following amounts (based on the dry weight) of ingredients were used:

Paper dust 80-90%, binder 2-3%, blowing agent 3-20% and / or a foaming agent 5-20%, and optionally substances, as defined in the previous text, in an amount of 3-15%.

In a microwave drying process, the liquid and dry components were premixed separately in two containers. Thereafter, the liquid phase was mixed with the dry phase, filled into a mold and dried. During the drying process, the porosity of the foam material was created by the chemical reaction of the blowing agent or foaming agent.

In a dry kiln drying process (60-180 ° C and atmospheric pressure), all the substances were placed in a container and mixed. It was important to ensure a sufficient energy input in the mechanical foaming. The mass was stably foamed by the added blowing agent or foaming agent and placed in a mold. During the drying process, only the water was removed from the mass, but the structure of the foam was retained.

In the production by means of "freeze gelation", all substances were homogenized in a container over a certain period of time and placed in a mold. This was cooled to -80 ° C and dried in the ambient air. The porosity of the foam material resulted in this case from the water crystals that resulted from the freezing of the water. In this case, silica sol was used as binder.

Claims (8)

Foam material obtained by foaming the constituents of the foam material in the presence of a foaming or blowing agent and then curing by drying At least 50% by weight, based on the total weight of the foam material, of paper dust arising as a waste product in waste paper recycling, the waste product having a very low fiber content, • 2-5% by weight, based on the total weight of the foam material, of carboxymethyl cellulose as a natural, starch-free binder. A foam material according to claim 1, wherein the proportion of the natural, starch-free binder in the foam material is 3% by weight, based on the total weight of the foam material. Foam material according to claim 1 or 2, wherein additionally fungicidal water repellents and / or flame retardants are contained. A foam material according to claim 3, wherein the fungicide is a base. Foam material according to claim 3 or 4, wherein the hydrophobing agent is a siliconate, siloxane, silicone oil or water glass. Foam material according to one of claims 3 to 5, wherein the flame retardant is a borate, aluminum hydroxide, magnesium hydroxide, ammonium polyphosphate, sodium sulfate, a compound from the group of alums or ammonium sulfate. Foam material according to one of the preceding claims, wherein the foam material has pores of a diameter in a range of 1 micron-20 mm. Use of the foam material according to one of the preceding claims as an insulation board.

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