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US-12624145-B2 - Binding composition for several applications

US12624145B2US 12624145 B2US12624145 B2US 12624145B2US-12624145-B2

Abstract

The present invention relates to an aqueous binding composition containing a) a reducing sugar; b) ammonium sulphamate and/or sulphamate of an alkaline or alkaline-earth metal; c) a pH-adjusting agent selected from ammonium hydroxide (NH4OH), an organic and/or inorganic ammonium salt and/or an organic amine; and a resin (or pre-condensate) obtained by reaction of a polyaldehyde, a urea compound and at a lignin sulphonate and/or a condensation derivate thereof with a polyaldehyde, the resin being present in a percentage of at least 10% by weight on the dry weight of the composition. The binder may be efficiently used to bind cotton fibres, cellulose fibres, organic tissues, coal dust, natural and artificial inorganic fibres, thereby obtaining products with good mechanical properties.

Inventors

  • Marco La Greca
  • Roberto Massini

Assignees

  • STM TECHNOLOGIES S.R.L.

Dates

Publication Date
20260512
Application Date
20210524
Priority Date
20200525

Claims (20)

  1. 1 . A formaldehyde-free aqueous binding composition comprising: a reducing sugar; ammonium sulphamate and/or a sulphamate of an alkaline or alkaline-earth metal; a pH-adjusting agent selected from the group consisting of ammonium hydroxide (NH 4 OH), an organic and/or inorganic ammonium salt and/or an organic amine; and a resin (pre-condensate) obtained by reaction of a polyaldehyde, an urea compound and a lignin sulphonate and/or a condensation derivate thereof with a polyaldehyde, said resin being present in a percentage of at least 10% by weight on the dry weight of the composition.
  2. 2 . The binding composition according to claim 1 , wherein the reducing sugar is present in a total amount of from 50% to 75%.
  3. 3 . The binding composition according to claim 1 , wherein the ammonium sulphamate and/or sulphamate of an alkaline or alkaline-earth metal, is/are present in a total amount of between 8 and 20% by weight, the sulphamate of an alkaline or alkaline-earth metal being sodium sulphamate, potassium sulphamate or calcium sulphamate.
  4. 4 . The binding composition according to claim 1 , wherein said pH-adjusting agent is present in an amount of at least 7%, to adjust the pH to values of between 6 and 9.
  5. 5 . The binding composition according to claim 1 , wherein said organic ammonium salt is the ammonium salt of an acid selected from the group consisting of citric acid, tartaric acid, glycolic acid, malic acid and lactic acid.
  6. 6 . The binding composition according to claim 1 , wherein said organic amine is selected from the group consisting of 2-amino-2-methyl-propanol (AMP), hexamethylenediamine and bis(hexamethylene)triamine.
  7. 7 . The binding composition according to claim 1 , wherein said resin (pre-condensate) is present in a percentage between 10% and 30% by weight on the dry weight of the composition.
  8. 8 . The binding composition according to claim 1 , wherein said polyaldehyde is a non-polymeric dialdehyde, said urea compound is urea and said lignin sulphonate is selected from ammonium salts or salts of alkaline or alkaline-earth metals with lignin sulphonic acid.
  9. 9 . The binding composition according to claim 1 , wherein said resin is obtained by reacting a mixture comprising from 35% to 65% of polyaldehyde, from 15% to 45% of urea compound and from 5% to 40% of a lignin sulphonate and/or a condensation derivate thereof with a polyaldehyde, wherein the percentages are by weight on the dry weight of the mixture resulting at the end of the addition of all the said components, at a temperature of between 60° C. and 100° C., for a time sufficient to substantially complete the reaction.
  10. 10 . The binding composition according to claim 1 , wherein said condensation derivate is obtained by reacting said lignin sulphonate with a polyaldehyde at a temperature of between 50° C. and 70° C.
  11. 11 . The binding composition according to claim 1 , further comprising 5-8% of a mineral oil, 0.1-0.2% of an amino-silane, 0.1-0.5% of polysiloxanes or mixtures thereof.
  12. 12 . The binding composition according to claim 1 , further comprising an acrylic component having molecular weight of between 3,000 and 10,000.
  13. 13 . A process for preparing a fibrous material starting from free mineral fibres, said process comprising the steps of: forming free mineral fibres of rocky or glassy material; applying an aqueous binding composition according to claim 1 to said free mineral fibres, thus forming mineral fibre agglomerates with said binding composition; and subjecting said agglomerates to a thermal treatment at a temperature capable of hardening said binding composition, thus obtaining said fibrous material.
  14. 14 . The process according to claim 13 , wherein the thermal treatment occurs at a temperature of at least 180° C.
  15. 15 . A mineral fibrous material obtained by the process according to the claim 13 .
  16. 16 . The mineral fibrous material according to claim 15 , which is a glass wool fibrous material having one or more of the following properties: density from 6 to 110 kg/m 3 ; solid binder content from 5 to 20% parting strength of at least 100 gf/f according to the standard ASTM C 685-90; at least 100% thickness recovery after compression for rolled blankets packed under pressure (compression ratio more than 4.5) as determined by thickness measure according to UNI:EN 823:2013; and at least 100% thickness recovery after compression for boards packed under pressure as determined by thickness measure according to UNI:EN 823:2013.
  17. 17 . The mineral fibrous material according to claim 15 , which is a rock wool fibrous material having one or more of the following properties: density from 20 to 250 kg/m 3 ; solid binder content from 1.5 to 20% at least 60 kPa at the compression test according to the standard UNI EN 826:2013; and at least 100% thickness recovery after compression as determined by thickness measure according to UNI:EN 823:2013.
  18. 18 . The binding composition according to claim 2 , wherein the reducing sugar is selected from the group consisting of monosaccharides glucose, fructose, galactose, xylose, arabinose, ribose, lyxose, mannose and rhamnose.
  19. 19 . The binding composition according to claim 1 , wherein the reducing sugar is a polysaccharide having a weight average molecular weight lower than 1,000,000, and said polysaccharide being used after acid treatment.
  20. 20 . The binding composition according to claim 8 , wherein the non-polymeric dialdehyde is glyoxal, glutaraldehyde, 1,6-hexanedial or 1,4-terephthalic dialdehyde and the lignin sulphonate is selected from sodium lignin sulphonate, potassium lignin sulphonate, magnesium lignin sulphonate, calcium lignin sulphonate, ammonium lignin sulphonate and combinations thereof.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a 371 of PCT/EP2021/063745, filed May 24, 2021, which claims the benefit of Italian Patent Application No. 102020000012220, filed May 25, 2020. FIELD OF APPLICATION In its most general aspect, the present invention relates to an aqueous binding composition (binder) which has several applications. In particular, the present invention relates to an aqueous binding composition comprising at least one reducing sugar, a sulphamate and a resin (hereinafter also referred to as pre-condensate) obtained by reaction between a polyaldehyde, a urea compound and at least one lignin sulphonate. BACKGROUND OF THE INVENTION Mineral fibrous materials, widely used as both thermal and acoustic insulating materials, for example in residential and industrial buildings, are known in the art. Said materials are formed by mineral fibres joined with each other by binding compositions (binders), usually aqueous, which comprise a polymerizing/cross-linking agent, and which are thermosetting and capable of firmly joining the fibres by high-temperature thermal-mechanical treatments. In this regard, the process for preparing said mineral fibrous materials generally comprises a first step of forming so-called “free” (i.e. not joined with each other) mineral fibres, followed by a step of impregnating at high temperature said free fibres with binding compositions which, due to the contact and the high temperatures, polymerize, thereby firmly joining the fibres with each other, giving shape and texture to the finished product. The binding compositions to be applied onto the mineral fibres are generally in the form of an aqueous solution containing the thermosetting resin and additives such as a cross-linking catalyst for the resin, a silane facilitating the fibre-resin chemical binding, an anti-dust mineral oil, etc. The binding composition is generally applied onto the fibres by spraying. The properties of the binding composition depend to a large extent on the characteristics of the resin. With regards to the application, the adhesive composition must be easy to spray and it must be possible to deposit it onto the surface of the fibres so as to efficiently bind them. Moreover, the resin should be stable for a given time period before being used to form the binding composition, said composition being generally prepared just before using it by mixing the resin and the above mentioned additives. Regarding the compliance with the regulations in force, the resin must be not polluting, i.e. it must contain—and should generate during the bonding step or later—the minimum possible quantity of compounds which can be harmful to human health or to the environment. The most commonly used thermosetting resins are phenolic resins of the resole class. In addition to their good cross-linking capability at the temperature of application onto mineral fibres, said resins are relatively inexpensive. The most common resoles are obtained by condensation of phenol and formaldehyde, in the presence of a base catalyst. These resoles contain a certain proportion of free monomers, in particular formaldehyde, whose presence is undesirable because of its known harmful effects. It has been long proven that formaldehyde is a dangerous carcinogenic agent. Therefore, resole-based resins are generally treated with urea, which reacts with free formaldehyde, thereby forming phenol-urea-formaldehyde copolymers. However, it has been observed that, under conditions of temperature of resin cross-linking, the urea-formaldehyde condensates are unstable; they decompose resulting again in formaldehyde and urea, which at least partially degrade in ammonia, and are released into the environment, in particular into the working environment. Regulations on environment protection have become more and more stringent and force producers of insulating products to find solutions which allow further reduction in the levels of undesirable emissions (volatile compounds), in particular of formaldehyde. For this purpose, several techniques for reducing emissions of undesirable compounds, in particular formaldehyde, of the binding compositions for mineral fibres as much as possible are known in the art. For example, application WO 2012076462 and U.S. Pat. No. 8,552,140 describe phenolic-resin-based binding compositions for mineral fibres, to which dextrose or Maillard reagents comprising a carbohydrate and an amine, respectively, as scavenger for formaldehyde, are added. However, binding compositions of said type still release significant levels of formaldehyde. Moreover, several aqueous binding compositions containing compounds able to polymerize by a Maillard reaction (for a general reference to Maillard reaction see for example GP Ellis et al., Advances in Carbohydrate Chem, 1959, pp. 63-134) are known in the art, such as sugars and proteins, or poly- or monocarboxylic acids and an ammonia source, and further comprising different types