WO2008065687A2

WO2008065687A2 - Process for making expanded thermoformed goods

Info

Publication number: WO2008065687A2
Application number: PCT/IT2007/000708
Authority: WO
Inventors: Rossano Ragazzini
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-10-18
Filing date: 2007-10-10
Publication date: 2008-06-05
Anticipated expiration: 2009-04-18
Also published as: EP2076473A2; WO2008065687A3; ITFI20060252A1

Abstract

Process for the production of expanded thermof ormed goods comprising the preparation of a mixture to be put in a forming mould and subsequently submitted to baking, characterised in that said mixture comprises glass particles, CaSO4 and a carbonizable substance.

Description

TITLE

Process for making expanded thermoformed goods

DESCRIPTION

The present invention relates to a process for making expanded thermoformed goods.

More particularly, a process according to the present invention comprises the step of mixing glass particles with an expanding agent and in submitting the mixture so obtained to a baking process, as indicated in claim 1. Further features of the present invention are the subject of the dependent claims.

Thanks to the present invention, it is possible to realise mixtures having optimal plasticity and formability features so as to produce light goods which are particularly suitable for applications in the building industry. The features of the thus obtained goods are programmable by adjusting the quantities of the mixture components and by acting on the process parameters, as indicated in a more detailed way in the following description. Moreover, a process according to the present invention can be carried out without using special equipments or machines and it can be managed also by not particularly qualified personnel. The simplicity in the execution of the present process offers further advantages, even in economical terms, which positively reflect on the fabrication costs of the goods . These and other advantages and characteristics of the invention will be best understood by anyone skilled in the art thanks to the following description in conjunction which refers to possible ways to carry out the present process. As already said, a process according to the present invention consists in mixing glass particles with an expanding agent and submitting this mixture to a baking process.

In principle, the quantity of glass to be used is comprised between 90 % and 99 % while the quantity of expanding agent to be used is comprised between 1 and 5 % by weight of the mixture.

The glass can be flour-like or sand-like.

It is pbssible to use glass derived from differentiated waste collection.

Some examples concerning a process according to the present invention are listed below.

Example 1

A gypsum mortar is prepared using glass flour (granulometry 50-100μ ) for 60-70% by weight and

2-10 % carbon powder by weight. Then the mortar is poured or pressed into a mould so as to realise a moulded product having the desired shape and size.

The gypsum acts both as a crude binding agent, ensuring high formability even when moulds having particularly complex shapes are used, and as an expanding agent. After a predetermined time, which is necessary for the "setting" of gypsum, the mould is opened and the moulded product is 'baked in a furnace. The baking temperature can be comprised between 900 and 1100° C in relation to the quantity of expanding agent used to realise the mixture.

Preferably, the temperature of 900° C is reached in about 2 hours, then the material is brought to a temperature of 1100 C in about 1 hour. An air cooling phase of the product removed from the furnace follows this step.

During baking, the carbon monoxide (due to the presence of the carbon powder) reacts with the calcium sulphate of the gypsum. A resistant or "bearing" calcium silicate structure is formed in the product being baked and bubbles of CO₂, SO₂ and SO₃ develop. At least part of the bubbles is trapped inside the material being baked, which, at this point of the process, is in a plastic- viscous state and causes it to expand. Example 2

The mixture components are the same as those of the previous example and powdered gypsum is used instead of a gypsum mortar, and the baking process takes place in a muffle furnace. In this case, however, it is preferable to use a gypsum quantity comprised between 2 and 10 %. Example 3 The composition mentioned in example 1 stays the same and, if a minor formability of the mixture is accepted, the glass can be sand-like with an irregular granulometry, instead of being flour-like. Example 4 Potassium permanganate (KMnO₄) is used in a quantity- comprised between 1% and 5% by weight of the mixture, CaSO₄ in a quantity comprised between 20% and 30% by weight of the mixture, 70-74% of glass flour, and 5 % organic fibres (for example paper fibers) by weight of the mixture which constitute a carbonizable agent. The mixture is brought to a temperature of 800 ⁰ C in 1 hour, then to 950 ° C in 20-30 minutes. Between 700 and 900 ° C the potassium permanganate frees oxygen, and there is the formation of manganese (MnO₂) and manganese silicate. The oxygen bubbles determine an increase in volume of the material being baked. The manganese acts as a bleaching agent if its percentage is inferior to 3%. If greater amounts of the indicated expanding agent are used, the finished product will take a violettish coloration.

In practice, by adjusting the quantity of potassium permanganate in the starting mixture, it is possible to adjust the quantity of gaseous bubbles per unit volume and the colour of the finished product, which can therefore be lighter or darker. Moreover, by using potassium permanganate it is possible to obtain a greater dimensional homogeneity of the bubbles . Example 5

A mixture containing 10-30% by weight of CaSO₄, 2-5% of KAl(SO₄), 5-10% of paper fibers and glass particles (in a quantity necessary to reach 100% by weight of the mixture) is prepared. The mixture is then brought to a temperature of 900 ° C in two hours and then to a temperature of 950-1000 ° C in 20 minutes. A cooling phase follows this phase (the cooling can be either rapid or slow) . In this case, a vitreous sponge-like product is obtained. Example 6

A mixture containing 10-30% by weight of CaSO₄, 2-5% of BaSO₄, 5-10% of paper fibers and glass particles (in a quantity necessary to reach 100 % by weight of the mixture) is prepared. The mixture is brought to a temperature of 900°C in two hours and then to 1000-1050 ° C in 30 minutes. A cooling phase follows this phase (the cooling can be either rapid or slow) . In this case, a vitreous sponge-like product is obtained like in the case of example 5 but with gaseous bubbles having a minor volume. BaSO₄ facilitates continuity in the formation of gaseous bubbles during the glass fusion above 1000 ° C and it is preferably used in a mixture with high- temperature-fusing glass. Example 7 A mixture containing 10-30 % by weight of CaSO₄, 2-5 % of NaSO₄, 5-10% of paper fibres and glass particles (in a quantity necessary to reach 100% by weight of the mixture) is prepared. The mixture is brought to a temperature of 800 ° C in 3 hours and then to a temperature of 1050 ° C in an hour. An air cooling follows. Na₂SO₄ facilitates continuity in the formation of gaseous bubbles during the glass fusion between 750 ° C and 1050 ° C and it is preferably used in a mixture with low-temperature- fusing glass. Example 8

A mixture containing 10-30 % by weight of CaSO₄, 2- 5% of MgSO₄, %-10% of paper fibers and glass particles (in a quantity necessary to reach 100% by weight of the mixture) is prepared. The mixture is brought to a temperature of 800 C in 3-4 hours and then to 1050 ° C in 2 hours. An air cooling follows. The effect of MgSO₄ is analogous to that of CaSO₄ described in Example 1. Example 9

A mixture containing 10-30% by weight of CaS04 , 2-5% of CuSO4. 5-10% of paper fibers and glass particles ( in a quantity necessary to reach 100% by weight of the mixture) is prepared. The mixture is brought to a temperature of 850 ° C in 3 hours and then to 1050 ⁰ C in 1 hour. An air cooling follows. The presence of copper determines an increase in the viscosity range of the glass, as, during the process, copper silicate is formed. This helps holding of the most voluminous gaseous bubbles . Example 10

A mixture containing 10-30% by weight of CaSO₄, 2-5 % of FeSO₄, 5-10% of paper fibers and glass particles (in a quantity necessary to reach 100 % by weight of the mixture) is prepared. The mixture is brought to a temperature of 850 ° C in 3 hours and then to 1000 ° C in 2 hours. An air cooling follows. The presence of FeSO₄ determines an effect which is opposite to that of CuSO₄ indicated in Example 9, i.e. it increases the fluidity range of the glass and reduces the viscosity thereof. Example 11 A mixture containing 10-30% by weight of CaSO₄ , 2- 5% of ZnSO₄, 5-10 % of paper fibers and glass particles (in a quantity necessary to reach 100% by weight of the mixture) is prepared. The mixture is brought to a temperature of 850 ⁰C in 4 hours and then to 1050 ⁰C in 1 hour. An air cooling follows. The effect determined by the presence of ZnSO₄ in the mixture is analogous to that indicated in Example 10 as regards the fluidity of glass, but this substance acts as a structuring agent, since zinc silicates are formed during baking. Example 12

A mixture containing 40-50% of CaSO₄, 1-5 % by weight of the mixture of paper fibers and glass particles in a quantity necessary to reach 100 % by- weight of the mixture) is prepared. The mixture is brought to a temperature of 1000-1100 ⁰C in about 8 hours and kept at this temperature for 30-60 minutes. An air cooling follows. The thus obtained product features a mixed alveolar structure (with open and closed alveoli) and is more thermally refractory than the products in the previous examples and it maintains good mechanical properties and features a higher density.

The time indicated in the previous embodiments can obviously vary in relation to the mass submitted to baking. Advantageously, in order to ensure a more uniform distribution of cavities in the finished product, it is foreseen to premix the expanding agent with carbon or with a relatively low-temperature carbonizable substance (i.e. carbonizable at 300- 400° C ), such as sugary substances, sawdust, vegetable wastes or paper fibers.

To widen the viscosity range of the vitreous material, it is possible to add blast furnace ashes, pozzuolana or clay.

Practically, all the execution details may vary in any equivalent way as far as the shape, dimensions, elements disposition, nature of the used materials are concerned, without nevertheless departing from the scope of the adopted solution idea and, thereby, remaining within the limits of the protection granted to the present patent.

Claims

1) Process for the production of expanded thermoformed goods comprising the preparation of a mixture to be put in a forming mould and subsequently submitted to baking, characterised in that said mixture comprises glass particles, CaSO₄ and a carbonizable substance.

2) Process according to claim 1 characterised in that an additive, selected among the following additives, is added to the mixture: NaSO₄, K₂SO₄, MgSO₄, BaSO₄, CaSO₄, KAl (SO₄) 2, FeSO₄, CuS04, MnS04.

3) Process according to claim 1, characterised in that said mixture comprises flour-like glass.

4) Process according to claim 1, characterised in that said mixture comprises sand-like glass. 5) Process according to claim 1 characterised in that said carbonizable substance is a sugary substance.

6) Process according to claim 1 characterised in that said carbonizable substance consists of sawdust.

7) Process according to claim 1 characterised in that said carbonizable substance consists of vegetable wastes .

8) Process according to claim 1 characterised in that said carbonizable substance consists of paper fibers