WO2004063259A1

WO2004063259A1 - Self-foamable organoclay/novolak nanocomposites and process thereof

Info

Publication number: WO2004063259A1
Application number: PCT/CA2004/000066
Authority: WO
Inventors: Abdeslam Kasseh; Jamal Chaouki; Elmekki Ennajimi
Original assignee: Abdeslam Kasseh; Jamal Chaouki; Elmekki Ennajimi
Priority date: 2003-01-16
Filing date: 2004-01-16
Publication date: 2004-07-29
Also published as: CA2416379A1

Abstract

The present invention discloses self-foamable and cross-linkable Organoclay/Novolak nanocomposites, foams and process thereof. The nanocomposites and foams disclosed herein comprise a layered silicate component and a novolak resin component. Nanocomposites compositions may also further comprise a surfactant and a curing agent. The layered silicate is intercalated by reaction with an intermediate having two functional groups, one of the group reacting with the layered silicate, the other participating to the condensation reaction with phenolic compounds. Foams generated from Organoclay/Novolak nanocomposites disclosed herein show improved mechanical properties. Furthermore, the process of producing such foams is greatly simplified by the use of water as the foam blowing agent. Water may originate from the condensation reaction of monomers (a phenol and an aldehyde) or from the volatile content of a novolak polymer.

Description

TITLE:

Self-foamable Organoclay/Novolak Nanocomposites and Process thereof

FIELD OF THE INVENTION

The present invention relates to self-foamable and cross-linkable Organoclay/Novolak nanocomposites having a novolak resin component and a layered silicate component, linked to each other through a covalent bond. More particularly it relates to compositions and foams derived from such nanocomposites. The present invention also encompasses a process for producing the self-foamable and cross-linkable nanocomposite material, as well as the process for producing the naήocomposite foam.

BACKGROUND OF THE INVENTION

Phenolic foams are recognized as versatile foam compositions, which may be used in a variety of materials, such as thermal insulator, fresh flower support, and building materials. Usually phenolic foams are based on resole-type resin which are expanded using chemical blowing agents. For example, conventional novolak-type phenolic foams described in French Patent application published under No. 2,502, 161 and U.S. Patent No. 4,698,370, are produced using chemical blowing agents, which may produce gas during composition curing at high temperature. Chemical blowing agents are expensive and some of them are even harmful to humans. Furthermore, a low compressive and flexural strength limit their use in constructional materials, which usually requires high mechanical properties and heat and flame resistance.

Various attempts have been made, to improve the compressive and flexural strengths of conventional novolak-type phenolic foams. For example, mixing novolak resin with an inorganic material, such as calcium carbonate, mica, perlite, vermiculite, obsidian, or the like was tried. Unfortunately, the incorporation of such inorganic materials results in a brittle composite material because of the very poor bond strength between the inorganic material and the novolak resin. Also, the addition of a large volume of inorganic material drastically reduces foaming and curing rates. It would be advantageous to have an alternative Organoclay/Novolak nanocomposite and process to make it (for example by polymerisation compounding). It would also be advantageous to have foams made from these nanocomposite and the process related thereof. More particularly, it would be advantageous to have a process of producing s uch foams w hich is g reatly s implified b y the u se of w ater a s the foam blowing agent. Disadvantages of using chemical blowing agents could therefore be avoided. In addition to the novolak-type resin and the layered-silicate, the nanocomposite compositions disclosed herein may comprise a surfactant and a curing agent. The resulting foams g enerated herein s how h igh m echanical p roperties a nd high curing and foaming rates.

The content of each publication, patent and patent aplication mentioned in the present application is incorporated herein by reference.

SUMMARY OF THE INVENTION

The present invention relates to self-foamable and cross-linkable Organoclay/Novolak nanocomposites, compositions, foams produced from these nanocomposites and process thereof. The nanocomposites and foams disclosed herein may comprise, for example, a 1 ayered s ilicate component and a n ovolak r esin component that may b e covalently linked (either directly or through an intermediate). Nanocomposite or foam composition may also further comprise a surfactant -and a curing agent. Processes of producing foams disclosed herein exploits water as a blowing agent. The blowing agent may be produced in situ during the generation of the Organoclay/Novolak nanocomposite from raw material (monomers; phenols and aldehydes). When the Organoclay/Novolak nanocomposite is produced from oligomer (novolak resin), water may originate from the volatile content of a novolak resin itself.

It is therefore provided, in a first aspect, a self-foamable and cross-linkable nanocomposite (foam) material, which comprises: a) a novolak type phenolic resin having a number-average molecular weight of 250 to 600 and having a volatile content of 1 to 10% (by weight; wt); b) a layered silicate uniformly dispersed in, said resin, said layered silicate having a layer thickness of about 7 to 12 A and an interlayer distance of at least about 4A, wherein said resin is connected to said layered silicate through an intermediate there between; c) a surfactant; d) a curing agent; and e) a produced in situ blowing agent.

In accordance with the present invention, the blowing agent may be produced (in situ) during the synthesis of the novolak resin, the blowing agent is preferably water.

In accordance with the present invention, the number-average molecular weight of the novolak resin may preferably be between 350 to 550.

Also in accordance with the present invention, the intermediate may be a covalent bond.

Further in accordance with the present invention the layered silicate may be, for example, a smectic clay selected from the group consisting of montmorillonite, nontronite, beidellite, volkonskoite, laponite, hectorite, saponite, sauconite, magadite, kenyaite, stevensite, vermiculite and mixtures thereof.

In accordance with the present invention, the content of said layered silicate may be between 0.05 to 60 parts by weight per 100 parts by weight of the novolak resin.

Also in accordance with the present invention, the layered silicate may be reactive (activated) and intercalated by the condensation reaction of the hydroxyl group of layered silicate with monomers or oligomers having bifunctional groups. The monomers or oligomers may be, for example, toluene diisocyanate, bisphenol A, hydroquinone and /or phenol-diol.

Further in accordance with the present invention, the nanocomposite may be obtained by reacting phenolic monomers in situ with layered silicate modified by a molecule having bifunctional groups.

Also in accordance with the present invention the monomers may be phenol (i.e., phenolic compound) (e.g., phenol, cresol, xylenol, resorcinol, hydroquinone and the like) and aldehyde (para-formaldehyde, acetaldehyde, furfural, and the like). In accordance with the present invention, the nanocomposite may be obtained by reacting the layered silicate modified by a molecule having bifunctional groups with novolak oligomer.

Further in accordance with the present invention, the volatile content in the novolak resin may preferably be water. The volatile content in the novolak resin may preferably be between 2 to 7% (by weight).

In a further aspect, the present invention provides a process for preparing a self- foamable and cross-linkable nanocomposite material involves (comprising) the following steps:

(i) preparing a reactive (activated) and intercalate layered silicate (organoclay); (ii) preparing an Organoclay/Novolak nanocomposite

(iii) mixing Organoclay/Novolak nanocomposite with surfactant; and

(iv) mixing Organoclay/Novolak nanocomposite with a curing agent to form powdered particles.

In accordance with the present invention, step (i) may be conducted in a reactor.

In accordance with the present invention, step (ii) may be conducted by: compounding polymerization of organoclay with novolak resin monomers and oligomers and surfactant to form the Organoclay/Novolak nanocomposite.

Also in accordance with the present invention, step (ii) may be conducted by: melt mixing the organoclay, surfactant and novolak resin through a compounding extruder to form the Organoclay/Novolak nanocomposite.

Further in accordance with the present invention step (ii) may be conducted by: adding organoclay into the reacting system of novolak-type phenolic resin before starting the reaction, and then melt mixing the mixture with the surfactant in a reactor or through a compounding extruder to form novolak-organocaly composite.

Also in accordance with the present invention, step (ii) may be conducted by: -melt mixing the surfactant and novolak resin in a reactor, and then cooling down, and

-dry mixing organoclay and the mixture of surfactant and novolak resin through the miller to form the Organoclay/Novolak (nano)composite

Step (ii) may also be conducted by:

-melt mixing the surfactant and novolak resin in a reactor, and then cooling down, and

-melt mixing organoclay and the mixture of surfactant and novolak resin through a compounding extruder to form the Organoclay/Novolak

(nano)composite.

In accordance with the present invention, step (iii) may be conducted by dry mixing Organoclay/Novolak nanocomposite with a curing agent using a miller to form powdered particles.

Also in accordance with the present invention, step (iii) may be conducted by melt mixing Organoclay/Novolak nanocomposite with a curing agent through a compounding extruder, and then pulverizing it into powdered particles using a miller.

Further in accordance with the present invention, the process for preparing novolak type phenolic nanocomposite foam may comprise heating self-foamable and cross- linkable nanocomposite powdered particles at 100 to 250 °C using a hot press or a hot furnace.

In an additional aspect, the present invention provides a composition for the manufacture of a self-foamable and cross-linkable Organoclay/Novolak nanocomposite, comprising: a) a novolak resin (i.e., novolak-type phenolic resin), and b) a layered silicate, wherein said resin is covalently linked to said layered silicate through an intermediate (linker).

In accordance with the present invention the novolak resin may have, for example, a number-average molecular weight of between 250 to 600, preferably between 350 to 550. Further in accordance with the present invention the novolak resin may have, for example, a volatile content of between 1 to 10% (by weight).

Also in accordance with the present invention, the layered silicate may have, for example, a layer thickness of between 7 to 12 A. Further in accordance with the present invention the layered silicate may have, for example, an interlayer distance of at least 4 A. .

In accordance with the present invention the composition may further comprise a surfactant, such as, for example a non-ionic surfactant. The surfactant may be selected, for example, from the group, consisting of non-ionic siloxane-oxyalkylene, oxyalkylated castor oil (castor oil/polyoxyalkylene copolymer) and polyoxyalkylated alkyl phenols and mixture thereof. In the above defined nanocomposite, the surfactant may be present in a range of between 0.05 to 20 parts by weight per 100 parts by weight of said novolak resin.

In accordance with the present invention, the composition may further comprise a curing agent, for example, hexamethylenetetramine or other curing agent. In the above defined composition, the curing agent may be present in a range of between 5 to 20 parts by weight per 100 parts by weight of said novolak resin.

Also in accordance with the present invention, the volatile content of the novolak resin may preferably be water.

Further in accordance with the present invention, the intermediate (linker) may be a covalent bond or it may be a molecule (having bifunctional groups) of formula; X-P- Y, wherein P is an organic structure and X and Y are independently selected from the group consisting of reactive groups such as -OH, -NCO, -Cl, -NH₂, etc. For example, the linker may be selected from the group consisting of resorcinol, bisphenol A, hydroquinone, toluene diisocyanate, thionyl chloride (Cl₂OS), adipoyl chloride, hexamethylenediamine, etc.

In the above defined composition, the layered silicate may be present in a range of between 0.05 to 60 parts by weight per 100 parts by weight of said novolak resin. In a further aspect, the present invention relates to a composition for the manufacture of (making) a foam comprising: " a) a novolak resin (i.e., novolak-type phenolic resin); b) a layered silicate; and c) a surfactant; wherein said resin is covalently linked to said layered silicate through an intermediate (linker).

In yet a further aspect, the present invention relates to a composition for the manufacture of a foam comprising ;

^' a) a self-foamable and cross-linkable Organoclay/Novolak nanocomposite having a layered silicate component and a novolak resin component, and b) a surfactant; wherein said layered silicate component and said novolak resin component are covalently linked through an intermediate (linker)

In accordance with the present invention, the compositions for the manufacture of a foam may further comprise a curing agent.

In accordance with the present invention, the nanocomposite may have, for example, a volatile content of between 1 to 10% (by weight).

In accordance with the present invention, the foams defined above may comprise, for example, a layered silicate present in a range of between 0.05 to 60 parts by weight per 100 parts by weight of said novolak resin, and a surfactant present in a range of between 0.05 to 20 p arts b y weight p er 1 00 parts by w eight of s aid n ovolak resin. Also in accordance with the present invention, the curing agent may be present in a range of between 5 to 20 parts by weight per 100 parts by weight of said novolak resin. The surfactant and curing agent may be those defined herein.

In an additional aspect, the present invention relates to a process for producing an (self-foamable and cross-linkable) Organoclay/Novolak nanocomposite comprising the step of covalently linking a layered silicate with a novolak resin. Suitable novolak resin and layered silicate may be as defined herein. In accordance with the present invention, the step of covalently linking may be performed by- olymerisation compounding. The step of covalently linking may be performed by reacting a functional group on said novolak resin with the activated surface of said layered silicate. The step of covalently linking may also be performed by reacting a linker having a bifunctional group with the activated surface of said layered silicate and with a novolak resin, said linker being of formula X-P-Y, wherein P is an organic molecule, andX and Y are independently selected from the group consisting of .-OH, -NCO, -Cl, -NH₂, etc. The linker may be selected, for example, from the group consisting of resorcinol, bisphenol A, hydroquinone, toluene diisocyanate, thionyl chloride (Cl₂OS), adipoyl chloride, hexamethylenediamine.

Further in accordance with the present invention, the silicate may be selected from the group consisting of smectic clay (montmorillonite, nontronite, beidellite, laponite, hectorite, saponite, sauconite, magadite, kenyaite, stevensite, and the like), vermiculite, halloysite, or sericite; or a swellable mica-based mineral, such as fluoromica or the like.

In another aspect, the present invention relates to a process for producing an (self- foamable and cross-linkable) Organoclay/Novolak nanocomposite comprising reacting (mixing) an activated layered silicate (e.g., a layered silicate modified by an intermediate (a molecule having bifunctional groups as defined herein)) with a phenolic compound and an aldehyde. The layered silicate may be as defined herein.

In accordance with the present invention, the nanocomposite may have, for example, a volatile content of between 1 to 10% (by weight). The volatile content may preferably be water.

In accordance with the present invention, the phenolic compound may be selected, for example, from the group consisting of phenol, cresol, xylenol, resorcinol, hydroquino- ne, and the like, and phenols modified with aniline, urea, melamine, or cashew and the like.

Also in accordance with the present invention, the aldehyde may be selected from the group consisting of formalin, para-formaldehyde, acetaldehyde, furfural, and the like. The process, in accordance with the present invention, may further comprise adding an acid catalyst.

It is to be understood herein that mixing may occur in successive step, such as for example, the addition of an aldehyde (such as formaldehyde) may be performed by adding it by drop while stirring (mixing). An acid catalyst may be added, for example, before the aldehyde.

In yet another aspect, the present invention provides a process for producing a foam comprising (melt) mixing (i.e., comprising a mixing step); a) a novolak resin (i.e., novolak-type phenolic resin) b) a layered silicate; c) a surfactant; and d) a curing agent.

It is to be understood herein that the process may be stopped at this step and the resulting mix may be shipped or stored (at a suitable temperature). The process may be completed later by for example, heating the mixture at a desired temperature.

In accordance with the present invention, the resin may be covalently linked to said layered silicate through an intermediate (linker) as described herein.

Also in accordance with the present invention, the volatile content of the novolak resin is mainly water.

The process, in accordance with the present invention, may further comprise pulverizing the above defined mixture.

The process, also in accordance with the present invention, may further comprise heating the mixture at a temperature of between 100 and 250 °C (using a hot press or a furnace)(and pressing it into a mold). Heating may promote the evaporation of water contained in the novolak resin and produced from the condensation of the phenolic compound and the aldehyde. Water, upon evaporation may then act as a blowing agent. Excess water may be removed by distillation under vacuum.

In accordance' with the present invention, the surfactant may be selected from the group consisting of non-ionic siloxane-oxyalkylene, oxyalkylated castor oil and polyoxyalkylated alkyl phenols and mixture thereof.

Also in accordance with the present invention, the curing agent may be, for example, hexamethylenetetramine, etc. .

In an additional aspect, the present invention relates to a process for producing a (Organoclay/Novolak nanocomposite) foam comprising; (melt) mixing (i.e., comprising a mixing step); a) an Organoclay/Novolak nanocomposite having a layered silicate component and a novolak resin component ; b) a surfactant; and c) a curing agent.

In accordance with the present invention, the layered silicate component and the novolak component may be covalently linked through an intermediate (i.e., a covalent bond or a linker).

Also in accordance with the present invention, the Organoclay/Novolak nanocomposite may have a volatile content of between 1 and 10% (by weight). The volatile con- tent of the novolak resin may be water.

In accordance with the present invention, water may be used herein as a blowing agent.

The process, according to the present invention, may further comprise pulverizing the above defined mixture. The process, also in accordance with the present invention, may further comprise heating the mixture at a temperature of between 100 and 250 °C (using a hot press or a furnace) (and pressing it into a mold).

In another aspect, the present invention relates to a composition including a nanocomposite comprising a novolak resin covalently attached to a silicate material.

In accordance with the present invention, the.nanocomposite may further comprise a surfactant, such as those defined herein. It may also further comprise a curing agent, as defined herein.

In accordance with the present invention, the nanocomposite may further comprise water as a blowing agent.

In a further aspect, the present invention provides a method for producing a foam from an Organoclay/Novolak nanocomposite having a layered silicate component covalently linked (directly or through a linker) to a novolak resin component, said method comprising using water as a blowing agent.

In another aspect, the present invention provides a foam made from a self-foamable and cross-linkable Organoclay/Novolak nanocomposite having a layered silicate component and a novolak resin component, said foam having a compression strenght at break (room temperature, 0.1 in/min speed) of at least 15 MPa.

In accordance with the present invention, the nanocomposite may have a silicate component of 5 % (by weight). Also in accordance with the present invention, the silicate component may be montmorillonite.

In yet another aspect, the present invention provides a foam made from a self- foamable and cross-linkable Organoclay/Novolak nanocomposite having a layered silicate component and a novolak resin component, said foam having a compression strenght at break (room temperature, 0.1 in/min speed) of at least 40 MPa. In accordance with the present invention, the nanocomposite may have a silicate component of 10 % (by weight). Also in accordance with the present invention, the silicate component may be montmorillonite.

Also in accordance with the present invention the foam made from a self-foamable and cross-linkable Organoclay/Novolak nanocomposite may have a water absorption (room temperature, 36 h) of less than 10% (weight).

A "volatile content" as used herein relates to the content of a composition that generates a gas (vapor) upon heating.

In the process o f this invention, the foam composition may b e incorporated with a variety of flame retardants, such as halogen compounds (e.g., tetrabromobisphenol A, hexabromobenzene, Dechlorane, and chlorinated paraffin), phosphorus compounds (e. g., triphenyl phosphate and cresyldiphenyl phosphate) and boron compounds (e. g., borax and boric acid).

It is to be understood herein, that an "Organoclay/Novolak nanocomposite foam" may be distinguished from the "Organoclay/Novolak nanocomposite" at the physical level. For example, it is to be understood herein that the "Organoclay/Novolak nanocomposite" is the (non-expended) material used to produce the foam. The foam is expended by the blowing agent (water produced in situ), and thus comprises cavities (empty cells), dispersed throughout the foam.

It is to be understood herein, that if a "range" or "group" of substances or the like is mentioned with respect to a particular characteristic (e.g. temperature, pressure, time and the like) of the present invention, it relates to and explicitly incorporates herein each and every specific member and combination of sub-ranges or sub-groups therein whatsoever. Thus, any specified range or group is to be understood as a shorthand way of referring to each and every member of a range or group individually as well as each and every possible sub-ranges or sub-groups encompassed therein; and similarly with respect to any sub-ranges or sub-groups therein.

- with respect to a temperature of at least 100 °C, this is to be understood as specifically incorporating herein each and every individual temperature state, as well as sub-range, comprising 100 °C and above 100 °C, such as for example 101 °C, 105 °C and up, 115 °C and up, 102 °C to 150 °C, up to 210 °C, and 600 °C etc.;

- with respect to a compression strenght at break of at least 15 MPa this is to be understood as specifically incorporating herein each and every individual compression strenght, as well as sub-range, comprising 15 MPa and above, such as for example, 15.5 MPa, 20 MPa, 18 MPa, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1A is a graph illustrating the mechanical properties (storage modulus) of Novolak foam (pure Novolak) or the Organoclay/Novolak nanocomposite foams of the present invention; non-grafted nanocomposite foam (MMT-Na-Novolak (5 % wt) and grafted nanocomposites foam (MMT-TDI-BA-Novolak (5% wt) and MMT- Phenol-Novolak (5% wt)).

Figure IB is a graph illustrating the mechanical properties (storage modulus) of Novolak foam (pure Novolak) or the Organoclay/Novolak nanocomposite foams of the present invention; non-grafted nanocomposite foam (MMT-Na-Novolak (10% wt) and grafted nanocomposites foam (MMT-TDI-BA-Novolak (10% wt) and MMT- Phenol-Novolak (10% wt)).

Figure 2 A is a graph illustrating a thermogravimetric analysis of Novolak foam (pure Novolak) and Organoclay/Novolak nanocomposite foams of the present invention.

Figure 2B is a graph illustrating the thermal stability of Novolak foam (pure Novolak) and Organoclay/Novolak nanocomposite foams of the present invention.

Figure 3A is a graph illustrating the X-ray diffraction (XRD) spectra of MMT (unmodified) and MMT modified by phenol (MMT-phenol) or TDI-BA (MMT-TDI- BA).

Figure 3B is a graph illustrating the XRD spectra of Organoclay/Novolak nanocomposite foams of the present invention with 5 % wt montmorillonite obtained by compounding or by mixing; Na-MMT/Novolak (compounding, 5% wt), Na- Bisphenol/Noyolak (compounding, 5% wt), Na-TDI-BA/Novolak (compounding, 5% wt), Na-TDI-BA/Novolak (mixing, 5% wt).

Figure 3C is a graph illustrating the XRD spectra of Organoclay/Novolak nanocomposite foams of the present invention with 10 % wt montmorillonite obtained by compounding or by mixing; Na-MMT/Novolak (compounding, 10% wt), Na- Bisphenol/Novolak (compounding, 10% wt), Na-TDI-BA Novolak (compounding, 10% wt).

DETAILED DESCRIPTION OF THE INVENTION i The phenolic resin used in this invention is a powdered, novolak phenolic resin that is prepared by crushing the. thermoplastic condensation product formed by reacting one or more kinds of phenol with one or more kinds of aldehyde in the presence of an acid catalyst. Usually, it is cured with a hardener, such as hexamethylenetetramine (referred to as HMTA hereinafter).

Phenol (i.e., phenolic compound) used as a raw material for the phenolic resin includes, for example, phenol, cresol, xylenol, resorcinol, hydroquinone, and the like. It may also include those phenols modified with aniline, urea, melamine, or cashew. The aldehyde that may be used in the generation of the phenolic resin may include, for example, formalin, p ara-formaldehyde, acetaldehyde, furfural, and the like. The acid catalyst may include, for example, sulfuric acid, hydrochloric acid, phosphoric acid, and other inorganic acids; and formic acid, oxalic acid, acetic acid, p-toluene- sulfonic acid, and other organic acids.

The powdered novolak phenolic resin used herein may be, for example, a novolak resin with a number-average molecular weight of about 250 to 600 or preferably 350 to 550. With a number-average molecular weight lower than 250, the phenolic resin may be liable to cake during storage and undergo hardening and foaming reactions, which are undesirable for uniform foams. With a number-average molecular weight in excess of 600, the phenolic resin may be slow in hardening and foaming reactions and does not form a foam with a high expansion ratio. It is to be understood herein that although the use of novolak resin number-average molecular weight lower than 250 or higher than 600 may have some undesirable effects, in some circumstances, such material may prove to be useful. The volatile content of the novolak resin used herein is present in the range of 1 to 10% (by weight) or preferably present in the range of 2 to 7% (by weight). The volatile content might be measured according to ASTM D-4639. The volatile content of the novolak resin includes water and free phenol. In the present invention, water is used as a blowing agent and free phenol may find utility in the control the foaming rate. The amount of volatile content may vary to suit the desired final density of the phenolic foam.

During the foaming of the novolak-type phenolic nanocomposite, a surfactant is present in the chemical composition. Non-ionic siloxane-oxyalkylene, oxyalkylated castor oil and polyoxyalkylated alkyl phenols have been used successfully as surfactants bo individually and in combination. For the chemical composition, which is the basis of the invention, it is preferable to employ between 0.05 and 20% surfactant (by weight), preferably present in the range of 2 to 10% by weight.

A feature of the invention is that the inorganic fillers used herein are layered silicates, which are uniformly dispersed in the phenolic foam. The layered silicate imparts advantageous mechanical characteristics and heat and flame resistance to the phenolic foam.

A typical layered clay (or layered silicate) suitable for use herein may be a swellable clay material, either natural or synthetic, such as, for example, smectic clay, vermiculite, halloysite, or sericite; or a swellable mica-based mineral, such as fluoromica. Examples of suitable smectic clays are montmorillonite, nontronite, beidellite, laponite, hectorite, saponite, sauconite, magadite, kenyaite, stevensite, and the like. These layered clays may generally comprise particles containing a plurality of silicate platelets. They may be, for example, present in the range of 0.8 to 1.2 nm thick, may be. tightly bound together with an interlayer spacing of, for example, 0.4 nm or less and may contain exchangeable cations (e.g., Na⁺, Ca⁺², K⁺ or Mg⁺², etc) at the interlayer surfaces. It is to be understood herein that the thickness and interlayer spacing is not to be restricted to the above mentioned values. In some circumstances it might be useful to use layered silicate with greater or lower values of thickness and interlayer spacing. The layered clay may be used directly in phenolic foam without any treatment. However, it may be advantageous to use a layered clay that is modified by an organic molecule. Such modification (intercalation) may improve the interfacial strength between the silicate layer and the phenolic matrix.

The layered clay (i.e., layered silicate) may be intercalated (modified), for example, with an organic molecule (e.g., a swelling agent) capable of undergoing ion-exchange reactions with the cations present at the interlayer surfaces of the silicate layers. Suitable swelling agents include cationic surfactants such as ammonium (primary, secondary, tertiary and quaternary), phosphonium or sulfonium derivatives of aliphatic, aromatic or arylaliphatic amines, phosphines and sulfides. Such suitable swelling agents and processes for intercalating layered silicates are disclosed in U.S. Patent No. 4,472,538, 4,810,734, 4,889,885 as well as international patent application publication No. WO92/02582, the complete disclosures of which are incorporated herein by reference.

However, in the present application, a novel, intercalating approach is used for intercalating a layered silicate. This new approach is based on the condensation reaction of an organic molecule containing reactive groups (having bifunctional group, such as hydroxyl groups) with the interlayer surface of the layered silicate and subsequently with Novolak resin. The above mentioned organic molecule may be characterized by the following formula:

X-P-Y in which P stands for an organic structure, X and Y are reactive groups, such as -OH, -NCO, -Cl, -NH₂ and so on. Organic molecule of such formula include, for example, hydroquinone, resorcinol, bisphenol A (BA), linear novolak with a molecular weight of 250 to 600, toluene diisocyanate (TDI), thionyl chloride, adipoyl chloride, hexamethylenediamine, and the like.

The process of intercalating organic molecules into layered silicates, therefore producing an Organoclay/Novolak nanocomposite, may be carried out by a one or two steps reaction with or without catalyst.

A typical one step reaction may be, for example; -reacting the layered silicate with hydroquinone, resorcinol, bisphenol A or any suitable organic molecule of the above mentioned structure. The reaction may be performed, for example, using acetonitrile, toluene or cyclohexane as the solvent and with oxalic acid or hydrochloride as the catalyst.

A typical two-step reactions may be, for example; -reacting the layered silicate with TDI or thionyl chloride, and;

-reacting the above with BA, HMDA, novolak or hexamethylenediamine.

According to the present invention, the Organoclay/Novolak may be generated by either producing the Novolak-type resin in situ (by condensation reaction of the phenolic compound and the aldehyde as described above) during the intercalation process of the layered silicate or may be produced from novolak resin prepared in a separate process and then intercalated with the layered silicate.

Turning now to the preparation of the foam itself. The general steps involved in the preparation of the self-foamable novolak-type resin foam from the nanocomposite described above may be, for example; a) mixing the Organoclay/Novolak nanocomposite with a surfactant; and; b) mixing the above with a curing agent to form powdered particles.

More particularly, the surfactant may be added into the novolak resin (by melt mixing in a reactor or through a compounding extruder) before its reaction (linking to) with the (modified) layered silicate or may be added to the Organoclay/Novolak nanocomposite after its synthesis.

The organoclay may be added together with the surfactant into novolak resin by melt mixing in a reactor or through a compounding extruder. The formed Organoclay/Novolak nanocomposite material containing surfactant may then be , mixed with a certain amount of curing agent by miller to form a powdered particle.

The Organoclay/Novolak nanocomposite foam thus obtained is poured into a mold of prescribed shape. The mold is heated to between 100 and 250°C for 2 to 60 minutes for curing and foaming, using a heating furnace or hot press. In this way phenolic resin nanocomposite foam is obtained. With a heating temperature lower than 100°C, the reaction rate of curing and foaming of the phenolic resin nanocomposite foam material is low and the resulting foam is poor in compressive strength. With a heating temperature higher than 250 °C, the curing and foaming take place at such a high rate that the foam with compact cell structures is not obtained.

The process of this invention produces Organoclay/Novolak nanocomposite foam better in comparison with conventional foams. A small percentage of layered silicate can greatly improve the mechanical properties and it does not decrease the curing and foaming rates. It is suitable for the industrial production of phenolic resin nanocomposites foam.

The present invention will be further explained by the following non-limiting and comparative examples.

Production of Novolak resin 1 A 90% phenol liquid (188 g, 1.8 mol phenol) is heated to 100 °C in a three-neck flask equipped with a reflux condenser, stirrer, and dropping funnel. Oxalic acid (1.62 g) is loaded into the phenol melt. A 37% solution of formaldehyde (102.2 g, 1.26mol) is added by drops while stirring at 100 °C. After the addition by drops is complete, the reaction mixture is refluxed for 2 hours. A fraction of the water generated during the process is then removed by distillation under atmospheric conditions and at vacuum for 1 hour. The obtained product is poured on the aluminum paper. The Novolak resin 1 comprises water present in the range of 1 to 10% (by weight) as required for the subsequent generation of a foam from the self-foamable and cross-linkable Organoclay/Novolak nanocomposite.

Production of Novolak resin 2

A 90% phenol liquid (188 g, 1.8 mol phenol) is heated to 100 °C in a three-neck flask equipped with a reflux condenser, stirrer, and dropping funnel. Oxalic acid (1.62 g) is loaded into the phenol melt. A 37% solution of formaldehyde (80.3 g, 0.99mol) is added by drops while stirring at 100 °C. After the addition by drops is complete, the reaction mixture is refluxed for 2 hours. A fraction of the water generated during the process is then removed by distillation under atmospheric conditions until 105 ml water is distilled out. The obtained product is poured onto the aluminum paper. The Novolak resin 2 comprises water present in the range of 1 to 10% (by weight) as required for the subsequent generation. of a foam from the self-foamable and cross- linkable Organoclay/Novolak nanocopomsite. Production of Novolak resin 3

A 90% phenol liquid (188 g, 1.8 mol phenol) is heated to 100 °C in a three-neck flask equipped with a reflux condenser, stirrer, and dropping funnel. Oxalic acid (1.62 g) is loaded into the phenol melt. A 37% solution of formaldehyde (124.1 g, 1.53mol) is added by drops while stirring at 100 °C. After the addition by drops is complete, the reaction mixture is refluxed for 2 hours. A fraction of the water generated during the process is then removed by distillation under atmospheric conditions until 145 ml water is distilled out. The obtained product is poured onto the aluminum paper. The Novolak resin 3 comprises water present in the range of 1 to 10% (by weight) as required for the subsequent generation of a foam from the self-foamable and cross- linkable Organoclay/Novolak nanocomposite.

Production of MMT-TDI-BA

Two grams of Na-montmorillonite (Na-MMT), 0.9 g of toluene diisocyanate (TDI), 0.004 g of DBTDL (dibutyltin dilaurate) and acetonitrile (50 ml) were introduced into a glass reactor. The mixture was stirred for 6 hours at 60°C. Then, 1.6 g of BA was added into the mixture and the reaction was carried out for 2 hours. The obtained product was washed by acetonitrile in order to remove free TDI and BA monomers. The product is named MMT-TDI-BA.

Production of MMT-Phenol

Two grams of Na-montmorillonite (Na-MMT), 0.9 g of hydroquinone and 0.04 g of oxalic acid were introduced into a glass reactor containing 50 ml of acetonitrile. The reaction was conducted for 6 h at 80 °C under stirring. The final product was washed by acetonitrile or acetone up to no free hydroquinone monomer. The product is named MMT-phenol.

PRODUCTION OF NANOCOMPOSITES BY POLYMERIZATION COMPOUNDING

EXAMPLE 1: Production of MMT-Na-Novolak Nanocomposite 5 wt%

Three grams of Na-MMT, 56.4 g of phenol and 0.54 g of oxalic acid were introduced into a glass reactor. The mixture was stirred and heated at 100 °C and after 1 hour

36.5 ml of formaldehyde was added. The reaction was carried out while being stirred for 2 h 30 min. 32 ml of water were removed by distillation under vacuum. Nanocomposites thus produced comprise, water in an amount sufficient for the subsequent generation of a foam from the self-foamable and cross-linkable Organoclay/Novolak nanocomposite.

EXAMPLE 2: Production of MMT-Na-Novolak Nanocomposite 10 wt%

Six grams of Na-MMT, 56.4 g of phenol and 0.54 g of oxalic acid were introduced into a glass reactor. The mixture was stirred and heated at 100°C and after 1 hour 36.5 ml of formaldehyde was added. The reaction was carried out while being stirred for 2 h. 32 ml of water were removed by distillation under vacuum. Nanocomposites thus produced, comprise water in an amount sufficient for the subsequent generation of a foam from the self-foamable and cross-linkable Organoclay/Novolak nanocomposite.

EXAMPLE 3: Production of MMT-TDI-BA-Novolak Nanocomposite 5 wt%

Three grams of MMT-TDl-BA, 56.4 g of phenol and 0.54 g of oxalic acid were introduced into a glass reactor. The mixture was stirred and heated at 100°C and after 1 hour 36.5 ml of formaldehyde was added. The reaction was carried out while being stirred for 2 h. 32 ml of water were removed by distillation under vacuum. The nanocomposites, thus produced comprise water in an amount sufficient for the subsequent generation of generation of a foam from the self-foamable and cross- linkable organoclay/novolak nanocomposite.

EXAMPLE 4: Production of MMT-TDI-BA-Novolak Nanocomposite 10 wt%

Six grams of MMT-TDI-BA, 56.4 g of phenol and 0.54 g of oxalic acid were introduced into a glass reactor. The mixture was stirred and heated at 100°C and after 1 hour 36.5 ml of formaldehyde was added. The reaction was carried out while being stirred for 2 hours. 32 ml of water were removed by distillation under vacuum. Nanocomposites thus produced, comprise water in an amount sufficient for the subsequent generation of a foam from the self-foamable and cross-linkable Organoclay/Novolak nanocomposite.

EXAMPLE 5: Production of MMT-Phenol-Novolak Nanocomposite 5 wt%

Three grams .of MMT-TDI-BA, 56.4 g of phenol and 0.54 g of oxalic acid were introduced into a glass reactor. The mixture was stirred and heated at 100°C and after 1 hour 36.5 ml of formaldehyde was added. The reaction was carried out while being stirred for 2 hours. 32 ml of water were removed by distillation under vacuum. Nanocomposites thus produced, comprise water in an amount sufficient for the subsequent generation of a foam from the self-foamable and cross-linkable Organoclay/Novolak nanocomposite.

EXAMPLE 6: Production of MMT-Phenol-Novolak Nanocomposite 10 wt%

Six grams of MMT-phenol, 56.4 g of phenol and 0.54 g of oxalic acid were introduced into a glass reactor. The mixture was stirred and heated at 100°C and after 1 hour 36.5 ml of formaldehyde was added. The reaction was carried out while being stirred for 2 hours. 32 ml of water were removed by distillation under vacuum. Nanocomposites thus produced, comprise water in an amount (quantity) sufficient for the subsequent generation of a foam from the self-foamable and cross-linkable Organoclay/Novolak nanocomposite.

EXAMPLE 7: Production of MMT-TDI-BA-Novolak Nanocomposite

Two grams of Na-montmorillonite (Na-MMT), 0.9g of toluene diisocyanate (TDI) and 0.004g of DBTDL were put into a glass reactor containing 50 ml of acetonitrile. The reaction was then conducted for 6 h at 60 °C while being stirred followed by adding 2 ,4g of linear novolak (from example 3; Novolak resin 3 ) into the reaction mixture and reacting for 2 hours. The obtained product was washed by acetonitrile or acetone until no free TDI monomers and novolak polymers remained. The product is named MMT-TDI-BA-Novolak 1. Nanocomposites thus produced, comprise water in an amount sufficient for the subsequent generation of a foam from the self- foamable and cross-linkable Organoclay/Novolak nanocomposite.

EXAMPLE 8: Production of MMT-TDI-BA-Novolak Nanocomposite

A MMT-TDI-BA (7.5g), 90% phenol liquid (188g, 1.8mol phenol) was heated to 100°C in a three-neck flask equipped with a reflux condenser, stirrer, and dropping funnel. Oxalic acid (1.62g) was loaded into the phenol melt. A 37% solution of formaldehyde (102.2g, 1.26mol) was added by drops while being stirred at 100°C. After the addition by drops was complete, the reaction mixture was refluxed for 2 hours. After cooling down to 80°C, 5g Surfonic CO-42 was added into the mixture and stirred for 5 min. Some water was then removed by distillation. The obtained product was poured onto the aluminum paper and named MMT-TDI-BA-Novolak 2. Nanocomposites thus produced, comprises water in an amount sufficient for the subsequent generation of a foam from the self-foamable and cross-linkable Organoclay/Novolak nanocomposite.

PRODUCTION OF NOVOLAK NANOCOMPOSITES FOAM

Nanocomposites obtained by polymerization compounding

EXAMPLE 9:

The nanocomposites prepared by polymerization compounding were mixed with 10wt% of a curing agent, like hexamethylenetetramine (HMTA), and pulverized into powder. The powder was put into a mold and pressed to foam, for around 5 minutes at 130 °C. It was heated to 165-170 °C for 10-15 minutes. During all the presses, the pressure was kept at 5 psi. Then the mold was cooled down and the novolak nanocomposite foam was removed.

Nanocomposite obtained by mixing

EXAMPLE 10:

Then grams of novolak resin (production of novolak example 1), 0.5 g Na-MMT- TDI-BA-Novolak 2 and 0.5 g Surfonic CO-42 are put into a flask and heated to 95 °C, mixed for 5 minutes and cooled. The mixture was mixed with 1.1 g HMTA and pulverized into powder. The powdered Organoclay/Novolak nanocomposite material is poured into a 12 x 12 x 5 mm mold. The mold is installed on a hot press at 130 °C for 5 min and heated to 175 °C and kept 10 min at 175 °C. Then the mold is cooled down and the novolak nanocomposite foam is removed.

EXAMPLE 11:

Eleven grams. of novolak nanocomposite material (production of novolak resin 2), are added to 1.1 g HMTA and the mixture is pulverized into powder. The powdered novolak nanocomposite material is poured into a l2 x l2 x 5 mm mold and the mold is installed on a hot press at 130 °C for 5 minutes and heated to 175 °C. The temperature is kept at 175 °C for 10 min. The mold is cooled and the novolak nanocomposite foam is removed. EXAMPLE 12:

Ten grams of novolak resin (production of novolak resin 1) are added to 0.5 g Na- MMT (no any modification) and 0.5g Surfonic CO-42 into a flask, heated to 95 °C, mixed 5 minutes and cooled. The mixture is mixed with 1.1 g HMTA and pulverized into powder. The powdered novolak nanocomposite material is poured into a 12 x 12 x 5 mm mold, the mold is installed on a hot press at 130 °C for 5 min and heated to 175 °C. The temperateure is kept at 175 °C for 10 minutes. The mold is cooled and the novolak nanocomposite foam is removed.

EXAMPLE 13:

Ten grams of novolak resin (production of novolak resin 2) are added to 0.5 g MMT- TDI-BA-Novolak 2 and 0.5g Surfonic CO-42 into a flask, heated to 95 °C, mixed for 5 minutes and cooled. The mixture is mixed with 1.1 g HMTA and pulverized into powder. The powdered novolak nanocomposite material is poured into a l2 x l2 x 5 mm mold, the mold is installed on a hot press at 130 °C for 5 minutes and heated to 175 °C. The temperature is kept at 175 °C for 10 minutes. The mold is cooled and the novolak nanocomposite foam is removed.

EXAMPLE 14: Ten grams of novolak resin (production of novolak resin 3) are added to 0.5 g MMT- TDI-BA-Novolak 2 and 0.5g Surfonic CO-42 into a flask, heated to 95 °C, mixed for 5 minutes and cooled. The mixture is mixed with 1.1 g HMTA and pulverized into powder. The powdered novolak nanocomposite material is poured into a l2 x l2 x 5 mm mold, the mold is installed on a hot press at 130 °C for 5 minutes and heated to 175 °C. The temperature is kept at 175 "C for 10 minutes. The mold is cooled and the novolak nanocomposite foam is removed.

Results presented in Table 1 and 2 indicate that the foam generated from the self- foamable and cross-linkable Organoclay/Novolak nanocomposite and prepared by polymerization compounding have good mechanical properties in comparison with conventional phenolic foam nanocomposites. The compressive strengths at break are two times greater for our products (MMT-TDI-BA-Novolak (5% wt)) and there is also no break over 44.6 KN for the self-foamable and cross-linkable nanocomposite foam at 10% wt of MMT; for the conventional nanocomposite at 10% wt of MMT the break is obtained at 21.8 KN. The nanocomposites present a lower water adsorption. The storage modulus of the nanocomposite foam of the present invention which are prepared by .polymerization compounding is higher than that of conventional nanocomposite foam.

TABLE 1: Com ression stren th: room tem erature, 0.1 in/min s eed

TABLE 2: Water Absor tion (room tem erature, 36 hours

Claims

We claim:

1. A self-foamable and cross-linkable nanocomposite material, which comprises:

(a) a novolak type phenolic resin having a number-average molecular weight ₅ of 250 to 600 and having a volatile content of 1 to 10% (by weight);

(b) a layered silicate uniformly dispersed in said resin, said layered silicate having a layer thickness of about 8 to 12 A and an interlayer distance of at least about 4 A, wherein said resin is connected to said layered silicate through an intermediate there between; O (c) a surfactant;

(d) a curing agent; and

(e) a produced in situ blowing agent.

2. The self-foamable and cross-linkable nanocomposite material as claimed in claim _j 5 1 , wherein the blowing agent is produced in situ.

3. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the blowing agent is produced during the synthesis of novolak resin.

20 4. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the blowing agent is water

5. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the number-average molecular weight of the novolak resin is 350 to

25 550.

6. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein said intermediate is a covalent bond.

30 7. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein said layered silicate is a smectic clay selected from the group consisting of montmorillonite, nontronite, beidellite, volkonskoite, laponite, hectorite, saponite, sauconite, magadite, kenyaite, stevensite, vermiculite and mixtures thereof.

35

8. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the content of said layered silicate is 0.05 to 60 parts by weight per 100 parts by weight of the novolak resin.

9. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein said layered silicate is reactive and intercalated by the condensation reaction of the hydroxyl group of layered silicate with monomers or oilgomers having bifunctional groups.

10. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein said monomers or oligomers are toluene diisocyanate, bisphenol A , hydroquinone and /or phenol-diol.

11. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the nanocomposite is obtained by reacting phenolic monomers in situ with layered silicate modified by bifunctional groups.

12. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the said monomers are phenol and aldehyde.

13. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the said phenol are phenol, cresol, xylenol, resorcinol, hydroquinone and the like.

14 l..T Thhee self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the said aldehyde are para-formaldehyde, acetaldehyde, furfural, and the like.

15. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the nanocomposite is obtained by reacting the layered silicate modified by bifunctional groups with oligomer novolak.

16. The self-foamable and cross-linkable nanocomposite material as claimed in claim

1, wherein the surfactant is non-ionic.

17. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1 , wherein the surfactant is a castor oil/polyoxyalkylene copolymer.

18. The self/foamable and cross-linkable nanocomposite material as claimed in claim 5 1, wherein the content of the surfactant is 0.05 to 20 parts by weight per 100 parts by weight of the novolak resin.

19. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the curing agent is hexamethylenetetramine.

10

20. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the content of the curing agent is 5 to 20 parts by weight per 100 parts by weight of the novolak resin.

15 21. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the volatile content in the novolak resin is mainly water.

22. The self-foamable and cross-linkable nanocomposite material as claimed in claim 1, wherein the volatile content in the novolak resin is 2 to 7% (by weight).

20

23. A process for preparing a self-foamable and cross-linkable nanocomposite material involves the following steps:

(i) preparing a reactive and intercalate layered silicate; (ii) preparing an Organoclay/Novolak nanocomposite 25 (iii) mixing Organoclay/Novolak nanocomposite with surfactant; and

24. The process as described in claim 23, wherein step (i) is conducted in a reactor ,30 according to claim 9, 10, and 11.

25. The process as described in claim 23, wherein step (ii) is conducted by: compounding polymerization of organoclay with novolak resin monomers and oligomers; and surfactant to form the Organoclay/Novolak nanocomposite.

35

26. The process as described in claim 23, wherein step (ii) is conducted by: melt mixing the organoclay, surfactant and novolak resin through a compounding extruder to form the Organoclay/Novolak nanocomposite.

27. The process as described in claim 23, wherein step (ii) is conducted by: adding organoclay into the reacting system of novolak-type phenolic resin before starting the reaction, and then melt mixing the mixture with the surfactant in a reactor or through a compounding extruder to form novolak-organocaly composite.

28. The process as described in claim 23, wherein step (ii) is conducted by:

(a) melt mixing the surfactant and novolak resin in a reactor, and then cooling down, and

(b) dry mixing organoclay and the mixture of surfactant and novolak resin through the miller to form the Organoclay/Novolak composite

29. The process as described in claim 23, wherein step (ii) is conducted by:

(b) melt mixing organoclay and the mixture of surfactant and novolak resin through a compounding extruder to form the Organoclay/Novolak composite.

30. The process as described in claim 23, wherein step (iii) is conducted by: dry mixing Organoclay/Novolak nanocomposite with a curing agent using a miller to form powdered particles.

31. The process as described in claim 23, wherein step (iii) is conducted by: melt mixing Organoclay/Novolak nanocomposite with a curing agent through a compounding extruder, and then pulverizing it into powdered particles using a miller.

32. A process for preparing novolak type phenolic nanocomposite foam comprising heating self-foamable and cross-linkable nanocomposite powdered particles at 100 to 250 °C using a hot press.

33. A process for preparing novolak type phenolic nanocomposite foam comprising heating a self-foamable and cross-linkable nanocomposite powdered particles at 100 to 250 °C using a hot furnace.

34. A composition for the manufacture of a self-foamable and cross-linkable Organoclay/Novolak nanocomposite, comprising: a) a novolak resin; and b) a layered silicate, ' wherein said resin is covalently linked to said layered silicate through an intermediate.

35. The composition of claim 34, wherein said novolak resin has a number-average molecular weight of between 250 to 600.

36. The composition of claim 34, wherein said novolak resin has a volatile content of between 1 to 10% (by weight).

37. The composition of claim 34, wherein said layered silicate has a layer thickness of between 8 to 12 A.

38. The composition of claim 34, wherein said layered silicate has an interlayer distance of at least 4 A,

39. The composition of claim 34, further comprising a surfactant.

40. The composition of claim 39, wherein said surfactant is a non-ionic surfactant.

41. The composition of claim 40, wherein said surfactant is selected from the group consisting^' of non-ionic siloxane-oxyalkylene, oxyalkylated castor oil and polyoxyalkylated alkyl phenols and mixture thereof.

42. The composition of claim 39, further comprising

agent.

43. The composition of claim 42, wherein said curing agent is hexamethylenetetramine.

44. The composition of claim 36, wherein said volatile content is water.

45. The composition of claim 34, wherein said intermediate is a covalent bond.

46. The composition of claim 34, wherein said intermediate is derived from a molecule of formula; X-P-Y wherein P is an organic structure and X and Y are independently selected from the group consisting of reactive groups such as -OH, ^• -NCO, -Cl, -NH₂, etc.

47. The composition of claim 34, wherein said intermediate is selected from the group consisting of resorcinol, bisphenol A, hydroquinone, toluene diisocyanate, thionyl chloride, adipoyl chloride, hexamethylenediamine and the like.

48. The composition of claim 34, wherein said silicate is selected from the group consisting of smectic clay, vermiculite, halloysite, sericite, a swellable mica-based mineral, or the like.

49. The composition of claim 34, wherein said layered silicate is present in a range of. between 0.05 to 60 parts by weight per 100 parts by weight of said novolak resin.

50. The composition of claim 39, wherein said surfactant is present in a range of between 0.05 to 20 parts by weight per 100 parts by weight of said novolak resin.

51. The composition of claim 42, wherein said curing agent is present in a range of between 5 to 20 parts by weight per 100 parts by weight of said novolak resin.

52. A composition for the manufacture of a foam comprising: a) a novolak resin; b) a layered silicate; and c) a surfactant; wherein said resin is covalently linked to said layered silicate through an intermediate. o

53. The composition of claim 52, wherein said novolak resin has a number-average molecular weight of between 250 to 600.

54. The composition of claim 52, wherein said layered silicate is present in a range of between 0.05 to 60 parts by weight per 100 parts by weight of said novolak resin, and wherein said surfactant is present in a range of between 0.05 to 20 parts by weight per 100 parts by weight of said novolak resin.

55. The composition of claim 52, wherein said curing agent is present in a range of between 5 to 20 parts by weight per 100 parts by weight of said novolak resin.

56. A composition for the manufacture of a foam comprising ; a) a self-foamable and cross-linkable Organoclay/Novolak nanocomposite having a layered silicate component and a novolak resin component; and; b) a surfactant; wherein said layered silicate component and said novolak resin component are covalently linked through an intermediate.

57. The compositon of claim 56, further comprising a curing agent.

58. The composition of claim 56, wherein said layered silicate is present in a range of between 0.05 to 60 parts by weight per 100 parts by weight of said novolak resin, and wherein said surfactant is present in a range of between 0.05 to 20 parts by weight per 100 parts by weight of said novolak resin.

(

59. The composition of claim 57, wherein said curing agent is present in a range of between 5 to 20 parts by weight per 100 parts by weight of said novolak resin.

60. A process for producing an Organoclay Novolak nanocomposite comprising the step of covalently linking a layered silicate with a novolak resin.

61. The process of claim 60, wherein said novolak resin has a number-average molecular weight of between 250 to 600. a

62. The process of claim 60, wherein said novolak resin has a volatile content of between 1 to 10% (by weight).

63. The process of claim 60, wherein said layered silicate has a layer thickness of between 7 to 12 A.

64. The process of claim 60, wherein said layered silicate has an interlayer distance of at least 4 A.

65. The process of claim 60, wherein the step of covalently linking is performed by polymerisation compounding

66. The process of claim 60, wherein the step of covalently linking is performed by reacting a functional group on said novolak resin with the activated surface of said layered silicate.

67. The process of claim 60, wherein the step of covalently linking is performed by reacting a linker having a bifunctional group with the activated surface of said layered silicate and with a novolak resin, said linker being of formula X-P-Y, wherein P is an organic molecule, and X and Y are independently selected from the group consisting of -OH, -NCO, -Cl, -NH₂, and the like.

68. The process of claim 67, wherein said linker is selected from the group consisting of resorcinol, bisphenol A, hydroquinone, toluene diisocyanate, thionyl chloride, adipoyl chloride, hexamethylenediamine.

69. The process of claim 60, wherein said silicate is selected from the group consisting of smectic clay, vermiculite, halloysite, sericite, a swellable mica-based mineral, or the like.

70. A process for producing an Organoclay/Novolak nanocomposite comprising reacting an activated layered silicate with a phenolic compound and an aldehyde.

71. The process of claim 70, wherein said novolak resin has a number-average molecular weight of between 250 to 600.

72. The process of claim 70, wherein said novolak resin has a volatile content of between 1 to 10% (by weight).

73. The process of claim 70, wherein said layered silicate has a layer thickness of between 8 to 12 A.

74. The process of claim 70, wherein said layered silicate has an interlayer distance of at least 4 A.

75. The process of claim 70, wherein said phenolic compound is selected from the group consisting of phenol, cresol, xylenol, resorcinol, hydroquinone, and the like, and phenols modified with aniline, urea, melamine, or cashew and the like.

76. The process of claim 70, wherein said aldehyde is selected from the group consisting of formalin, para-formaldehyde, acetaldehyde, furfural, and the like.

77. The process of claim 70, further comprising adding an acid catalyst.

78. A process for producing a foam comprising mixing; a) a novolak resin, b) a layered silicate; c) a surfactant; and d) a curing agent.

79. The process of claim 78, wherein said novolak resin has a number-average molecular weight of between 250 to 600.

80. The process of claim 74, wherein said novolak resin has a volatile content of between 1 to 10% (by weight).

81. The process of claim 78, .wherein said resin is covalently linked to said layered silicate through an intermediate.

82. The process of claim 78, wherein said volatile content is water.

83. The process of claim 78, further comprising pulverizing said mixture.

84. The process of claim 83, further comprising heating the mixture at a temperature of between 100 and 250 °C.

85. The process of claim 78, wherein said surfactant is selected from the group consisting of non-ionic siloxane-oxyalkylene, oxyalkylated castor oil and polyoxyalkylated alkyl phenols and mixture thereof.

86. The process of claim 78, wherein said curing agent is hexamethylenetetramine.

87. A process for producing a foam comprising mixing; a) an Organoclay/Novolak nanocomposite having a layered silicate component and a novolak resin component, b) a surfactant; and c) a curing agent.

88. The process of claim 87, wherein said nanocomposite has a a volatile content of between 1 and 10% (by weight).

89. The process of claim 87, wherein said layered silicate component and said novolak component are covalently linked through an intermediate.

90. The process of claim 88, wherein said volatile content is water.

91. The process of claim 90, wherein water is used as a blowing agent in said process.

92. The process of claim 87, wherein said surfactant is selected from the group consisting of non-ionic^' siloxane-oxyalkylene, oxyalkylated castor oil and polyoxyalkylated alkyl phenols and mixture thereof.

93. The process of claim 87, wherein said curing agent is selected from the group consisting of hexamethylenetetramine, etc.

94. The process of claim 87, further comprising pulverizing said mixture.

95. The process of claim 87, further comprising heating the mixture at a temperature ofbetween l00 and250 °C.

96. A compositon including a nanocomposite comprising a novolak resin covalently attached to a silicate material.

97. The composition of claim 96, further comprising a surfactant.

98. The composition of claim 97, further comprising a curing agent.

99. The composition of claim 98, comprising water as a blowing agent.

100. A method for producing a foam from an Organoclay/Novolak nanocomposite having a layered silicate component covalently linked to a novolak resin component, said method comprising using water as a blowing agent.

101. A foam made from a self-foamable and cross-linkable Organoclay/Novolak nanocomposite having a layered silicate component and a novolak resin component, said foam having a compression strenght at break of at least 15 MPa.

102. The foam of claim 101, having a layered silicate component of 5 % (by weight).

103. The foam of claim 102, wherein said layered silicate component is montmorillonite.

104. The foam of claim 101, characterized in that th^ water absorption of said foam is less than 10% (by weight).

105. A foam made from a self-foamable and cross-linkable Organoclay/Novolak nanocomposite having a layered silicate component and a novolak resin component, said foam having a compression strenght at break of at least 40 MPa.

106. The foam of claim 105, having a layered silicate component of 10 % (by weight).

107. The foam of claim 106, wherein said layered silicate component is montmorillonite.

108. The foam of claim 105, characterized in that the water absorption of said foam is less than 10% (by weight).