This invention relates to a hybrid phenolic resm derivable from the initial reaction of two ofthe three components that are a phenol, a siloxane and an aldehyde, and then adding the third component to the initial reaction mixture and to a process for the synthesis thereof 5 It is well known to produce phenolic resins from a phenolic compound and an aldehyde such as formaldehyde Such phenolic resins find wide uses such as eg in the making of thermosetting resins, thixotropic compositions, foams, laminates, pipes, ducts, adhesives and coatings

It has now been found that the physical and fire resistant properties of such io phenolic resms can be improved significantly, if siloxanes are incorporated therein during their production in order to form hybnd resins

Accordingly, the present invention is a hybrid phenolic/polysiloxane resm denvable by

A reacting a phenolic compound with ϋ a a siloxane polymer or b an aldehyde and B reacting the reaction product of stage

(A)(a) with an aldehyde, or, 20 (A)(b) with a siloxane polymer to form the hybrid phenolic/polysiloxane resin, said resm having a siloxane content of 1-40% by weight ofthe total hybrid resm and a viscosity in the range of 100- 10000 mPa s

The hybrid phenolic/polysiloxane resin (hereafter termed "hybrid resin" for 2ι convenience) suitably has the following physical characteristics all by weight ofthe

total hybrid resin: i. a siloxane content of 1-40%; ii. a water content of < 15%; iii. a free aldehyde content of < 5%; and iv. a free phenolic compound content of < 15%.

By the expression "phenolic compound" as used herein and throughout the specification is meant a compound having phenolic hydroxyl groups. Thus, phenolic compounds used to form the hybrid resin may be one or more of phenol, the isomeric cresols, nonyl phenol, styrenated phenols, bromo-phenols, catechol, resorcinol, the isomeric xylenols and phenolic resins (derived from a phenolic compound and an aldehyde) having a molecular weight below 1000 preferably from 200 to 500. Of these, phenol itself and the isomeric cresols are preferred. By the expression "siloxane polymer" is meant here and throughout the specification compounds having a -Si-O-Si- grouping in their structure. Thus, the siloxane polymer used to form the hybrid resin is suitably alkoxy and/or silanol functional siloxane polymer having a molecular weight ranging from 1000 to 6000.

Of these, siloxane polymer marketed by Wacker Chemie under the trade name SY-

231 (which is a siloxane with alternating phenyl and methoxy group on its backbone in which the phenyl to methoxy group ratios is at least 1.4 per molecule and which has a molecular weight of about 1000) or the equivalent product, 3074 from Dow Corning, is preferred.

The aldehydes that may be used for making the hybrid resins ofthe present invention suitably comprise one or more of aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde and butyraldehyde or aqueous solutions thereof and is preferably formaldehyde which can be used as an aqueous solution thereof, ie formalin.

The two methods of forming the hybrid resin outline above are described below in some detail and each method has been sectionalised for clarity.

1. Method A(a) + Bf AUa): 1.1 Stage A(a) : Reacting the phenolic compound with a siloxane polymer: In this method, the phenolic compound is initially reacted with a siloxane polymer in the presence of a catalyst.

The amount ofthe siloxane polymer used in relation to the phenolic compound is suitably in the range by weight from 7 : 50 to 10 : 20, preferably about 7 : 30. For this reaction the catalyst may be alkaline, amphoteric or acidic,

but is preferably alkaline Examples of catalysts that may be used include inter a a an alkali metal hydroxide or an alkaline earth metal hydroxide. More specifically, the catalyst is preferably sodium hydroxide. The amount of catalyst used for this reaction is suitably below 10 parts by weight, preferably from 2 to 10, parts for every 100 parts ofthe phenolic compound used as the reactant. The catalyst may be used in conjunction with a co-catalyst Examples of co-catalysts that may be used include organo tin compounds, especially alkyl tin dicarboxylates wherein the alkyl group may contain 1-4 carbon atoms, and specifically dibutyl tin diacetate. Where a co-catalyst is used, it is suitably present in an amount from 0.1-4 parts for every 100 parts ofthe phenolic compound used as the reactant.

The reaction between the phenolic compound and the siloxane polymer is suitably carried out at a temperature in the range from 30 to 80°C, preferably from 40 to 50°C such as eg 40°C. The reaction is suitably carried out for a relatively short time ranging from 5 minutes to about 3 hours, preferably from about 20 minutes to about 2 hours, eg 30 minutes

The products from this stage A(a) ofthe method may comprise further polymerisation products since the siloxane polymers used as reactants have a tendency to polymerise in the presence ofthe catalysts ofthe type now used for this reaction Where such polymerisation occurs, it is important that the molecular weight of such a polymer is controlled so that it is within the range from 1000- 5000, preferably from 1000-3000 in order to prevent the siloxane polymers precipitating out as a separate phase in the reaction products. 1.2 Stage B(A)(a): Reaction of Product A(a) with an Aldehyde

The products from stage A(a) ofthe method are then reacted with an 5 aldehyde in a stage B The relative proportions ofthe reaction products from stage A(a) and the aldehyde for the condensation reaction in stage B is suitably in the range by weight from 1 . 2 to 2 1

The stage B condensation reaction is suitably carried out in the presence of a catalyst which is preferably alkaline and may be the same as that used in stage o A(a) In fact, if the reaction products from stage A(a) are used directly without being subjected to any separation stages, the catalyst present in stage A(a) products may be sufficient to effect condensation with the aldehyde in stage B The stage B(A)(a) condensation reaction with the aldehyde is suitably carried out a temperature in the range from 40 to 85°C, preferably from 60 to 80° C The duration of this stage B reaction is suitably from 30 minutes to 3 hours.

preferably from 45 minutes to 2 hours.

The products of this reaction are the desired hybrid resins. Neutralisation (to about pH 6) is carried out at a water content from 5-8% and then distillation is continued to a typical final water content of 2-3%. 2. Method A. b) + B(A).b.:

2.1 Stage Afb) : Reacting the phenolic compound with an aldehyde:

The products made by Method 1 above may also be made by reacting a phenolic compound initially with an aldehyde in the presence of a catalyst. For this stage A(b), the relative mole ratios ofthe aldehyde to phenolic compound used in this stage is suitably in the range from 1.1 : 1 to 2.5 : 1.

For this reaction A(b), the catalyst, as previously, may be alkaline, amphoteric or acidic, but is preferably alkaline. Examples of catalysts that may be used include inter alia an alkali metal hydroxide or an alkaline earth metal hydroxide. More specifically, the catalyst is preferably sodium hydroxide. The amount of catalyst used for this reaction is suitably in the range from 2 to 10 parts for every 100 parts ofthe phenolic compound used as the reactant. The catalyst may be used in conjunction with a co-catalyst. Examples of co-catalysts that may be used include organo tin compounds, especially alkyl tin dicarboxylates wherein the alkyl group may contain 1-4 carbon atoms, and specifically dibutyl tin diacetate. Where a co-catalyst is used, it is suitably present in an amount from 0.1-4 parts for every 100 parts ofthe phenolic compound used as the reactant.

Stage A(b) ofthe reaction between the phenolic compound and the aldehyde is suitably carried out at a temperature in the range from 30 to 70°C, preferably from 40 to 50°C such as eg 50°C. The reaction is suitably carried out for a time ranging from 30 minutes to about 3 hours, preferably from about 60 minutes to about 2 hours, eg 60 minutes.

The products from stage A(b) carried out using the phenolic compound and the aldehyde will comprise of mono-, di- and tri- additions of the aldehyde to the phenolic ring since such by-products have a tendency to be produced in the presence of the catalysts ofthe type now used for this reaction. Where such additions occur, it is important that the molecular weight ofthe product is controlled so that it is within the range from 150-8000. 2.2 Stage B(AHb): Reaction of Product A(b) with a siloxane polymer:

The reaction product from this stage A(b) is used for reaction with the siloxane polymer in stage B(A)(b). However, with this type of resin, the pH is

kept high at a value from pH 8-9 during distillation in order to promote co- condensation

The relative proportions of the reaction products from stage A(b) and the siloxane polymer in stage B(A)(b) is suitably in the range by weight from 20 1 to 2 1

The stage B(A)(b) reaction is suitably carried out in the presence of a catalyst which is preferably alkaline and may be the same as that used in stage A(b) In fact, if the reaction products from stage A(b) are used directly without being subjected to any separation stages, the catalyst present in stage A(b) products may be sufficient for the stage B(A)(b) reaction

The stage B(A)(b) reaction is suitably carried out at a temperature in the range from 35 to 85°C, preferably from 60 to 80°C The duration of this stage B(A)(a) reaction is suitably from 20 minutes to 3 hours, preferably from 45 minutes to 2 hours Whether the hybrid resins are produced by Method 1 or Method 2, the reaction between the stage A reaction products, and either the aldehyde or siloxane polymer in stage B may be carried out in the presence of a silane in order to facilitate and promote interaction between the organic and inorganic phases which may separate during the course ofthe reaction By a "silane" is meant here and throughout the specification a compound ofthe formula

R Si(OR') _4-t wherein R is an alkyl group and/or a functional amino group so that at least one of its R groups is a functional amino or epoxy group, R' is H, a C]-C alkyl group or combinations thereof and x has a value from 1 to 3 Thus, the OR' groups in the silane may be fully or partially hydrolysed, ie they may all be OH groups or all be O-Alkyl groups or any combinations thereof Those silanes having at least some free OH groups are preferred. A specific example of such a silane is n-(2- aminoethyl)-3-aminopropyltrihydroxy silane which can be represented by the formula NH ₂ CH ₂ CH ₂ NH(CH ₂ ) ₃ Si(OH) ₃ This reaction and the subsequent working up ofthe stage B reaction products from both Methods 1 and 2 is very similar in all other respects to the conventional production of a phenolic resole resin from a phenolic compound and an aldehyde

In the process ofthe present invention, it is preferable to add a small amount of one or more of the following compounds prior to distillation of the

s

stage B reaction products to reduce the water content thereof to below 15% l an acid to neutralise the alkaline catalyst, when used, π a surfactant such as an alkoxylated castor oil eg ethoxylate castor oil, to stabilise the resin/resole formed, and iii a glycol such as eg monoethylene glycol

It is preferable to reduce this water content to below 2% The hybrid resm product after vacuum distillation is also relatively low in free aldehyde content (usually < 5% by weight, preferably < 3% by weight) and free phenol content (< 15% by weight, preferably < 10% by weight) The hybrid resms are very sensitive to the presence of acids which initiate rapid curing ofthe resin Therefore, whilst stoπng the hybrid resins care should be taken to avoid contact with any acidic materials although such resins can be formulated with any other desired ingredients pπor to storage The hybrid resins, due to their relatively low water content, are stable and have reasonably long pot lives

The resultant hybrid resins can be used in many ofthe applications including the making of thermosetting resins, thixotropic compositions, foams, laminates, composites, pipes, ducts, linings, adhesives and coatings In using these hybrid res s to make any ofthe aforementioned products, it would be necessary to use an acidic curing agent (also known as a hardener) The curing agent is suitably selected from one or more of mineral acids, organic acids or a compound capable of giving rise to said acids under the curing conditions eg by hydrolysis Specific examples of mineral acids are hydrochloric acid, sulphuric acid, and phosphoric acid and partial esters thereof Specific examples of organic acids are the sulphonic acids, especially the xylene sulphonic acids and toluene sulphonic acids, particularly /ram-toluene sulphonic acid An example of a compound capable of giving rise to the acid curing agent under the curing conditions is an acyl halide It is preferable to use a combination of two or more of these such as eg a combination of a mineral acid and an organic acid A particularly preferred combination is that of a sulphonic acid and phosphoric acid An example of such a curing agent is Phencat ® 381 (ex C F Budenheim) comprising a partial phosphate ester (derived by reacting polyphosphoπc acid with a diol or a polyol) and 5% by weight of para- toluene sulphonic acid Use of such partial phosphate esters as hardeners for phenolic resins is claimed and described in our prior published EP-A-0539098 The amount ofthe acidic curing agent used is suitably in the range from 5-

15% by weight ofthe hybrid resin employed

The products made from the hybrid resins ofthe present invention can be subjected to elevated temperature during and/or after curing A feature ofthe hybrid resms ofthe present invention is that products such as composites formed therefrom show improved performance after such high temperature treatment.

The products derived from the hybrid resins ofthe present invention have enhanced impact strength, can tolerate higher burst pressures in pipe applications, have improved resistance to hydrolysis and other environmental weathering characteristics; have improved fire stability, and show improved film flexibility in coatings These characteristics are a particular improvement over those exhibited by epoxy resins conventionally used in such applications Furthermore, such resins can be produced more economically than epoxy resins

The present invention is further illustrated with reference to the following Examples EXAMPLE 1:

The following ingredients were used

CHARGE PARTS MASS (g)

Phenol 100 2000

Formalin (44% solution) 1 16 5 2330

Siloxane SY 231 15 530

25% Caustic soda soln 4 2 84

Monoethylene glycol 7* 227 p-TSA (65%o solution) - (92 ml)

Silane 1-6137 (ex Dow) 1 * 35

* - amount based on the final mass

Phenol, siloxane SY231 and caustic soda were charged into a reactor and initially heated to 40°C and blended for 45 minutes To this mixture was charged formalin and further heated to 60°C for 0 5 hrs The heating was continued further to raise the temperature to 80°C until the desired viscosity (21 8 mm ² /s) was obtained The reaction mixture was then neutralised with /^-toluene sulphonic acid (p-TSA) until the pH was 7 5 followed by addition of monoethylene glycol The resultant mixture was subjected to vacuum distillation to produce a hybrid resin The viscosity of this hybrid resin was adjusted by addition of water to 4200 mPa s (cPs) The hybrid resin so formed had a water content of 3 0 %, a free phenol

content of 9 9% and a free formaldehyde content of 2 0%. The silane was added to the hybrid resin EXAMPLE 2:

The following reactants were used in this Example

CHARGE PARTS MASS (g)

Phenol 100 2000

Formalin (44% solution) 116.5 2330

Siloxane SY 231 11 8 530

25% Caustic soda soln 4 2 84

Monoethylene glycol 5 227 p-TSA (65% solution) - (90 ml)

Silane 1-6137 (ex Dow) 1 18* 53

* - amount based on the siloxane used

Phenol, formalin and caustic soda solution were blended in a reactor at 40° C for 0 5 hour and then the temperature was raised to 60°C and maintained at that temperature for a further 0 5 hour to form an intermediate phenol-formaldehyde resin

To 100 parts of this intermediate resin (4500 g) was added the siloxane and silane and the resultant mixture was blended in a reactor at 35°C for 0 5 hour The alkali in the reaction mixture was then neutralised with^-TSA and the monoethylene glycol was then added The resultant product was then subjected to vacuum distillation The hybrid resin so formed had a viscosity of 3160 mPa s (cPs), a water content of 8%, a free phenol content of 8 9% and a free formaldehyde content of 1 2%

EXAMPLE 3:

The following reactants were used in this Example

CHARGE PARTS MASS (g)

Phenol 100 2000

Formalin (44% solution) 1 16.5 2330

Siloxane SY 231 15 530

25%o Caustic soda soln 4.2 84

Monoethylene glycol 7* 227 p-TSA (65% solution) - (90 ml)

Silane 1-6137 (ex Dow) 1 20

Metatincat® 702** 0 2 4

* - amount based on the final mass **- a dibutyl tin diacetate (ex ACIMA)

Phenol and the siloxane were blended and solubilized in a reactor by heating to 40°C The Metatincat® 702 catalyst was then added and stirred for about 30 minutes Thereafter the formalin and caustic soda were charged to the reactor and the temperature raised to 60°C and maintained at this temperature for 30 minutes The temperature was then raised to 80°C and maintained at that temperature until the viscosity of the mixture was 21.4 mm /s (cSt). The resultant product was then neutralised with -TSA until the pH was 7.3 and monoethylene glycol then added. This mixture was then subjected to vacuum distillation to reduce the water content thereof Thereafter the siiane was added. The hybrid resin so formed had a viscosity of 1700 mPa s (cPs), a water content of 4 4%, a free phenol content of 8 9% and a free formaldehyde content of 1 5%

EXAMPLE 4:

The following reactants were used in this Example

CHARGE PARTS MASS (g)

Phenolic resin* 100 4500

Siloxane SY 231 15 530

Monoethylene glycol 6** 233

25% Caustic soda soln - (15 ml)

Metatincat®702 0 2 4 p-TSA (75% solution) - (88 ml)

* - Tlie resin used was the mteπnediate produced in the initial stage of Example 2 above ** - amount based on the final mass

The intermediate phenolic resin was initially neutralised with p-TSA in a reactor until the pH thereof was 7 6 and then blended with the siloxane at 35°C for 20 minutes Thereafter, the Metatincat® 702 catalyst was added thereto and then monoethylene glycol was added The tin catalyst was then neutralised with a further aliquot ofthe caustic soda solution to bring the pH value to 8 0 The resultant mixture was subjected to vacuum distillation to reduce the water content thereof The final hybrid resin so formed had a viscosity of 3220 mPa s (cPs), a water content of 4 7%, a free formaldehyde content of 1 55% and a free phenol content of 8 4%

EXAMPLE 5:

The following ingredients were used

CHARGE PARTS MASS (kg)

Phenol 100 1310

Formalin (44% solution) 1 16 5 1526

Siloxane SY 23 1 17 2 225

25%o Caustic soda soln 4 2 55 p-TSA (65% solution) 6 4 84

Phenol, formalin and caustic soda were charged into a reactor and initially heated to 60°C and blended for 30 minutes until the viscosity at 25 °C was 13-15 mm ² /s (cSt) To this cooled mixture was charged the siloxane and the resultant mixture was subjected to vacuum distillation to produce a hybrid resin having water content of 5 - 10 % The reaction mixture was then neutralised with p-toluene sulphonic acid (p-TSA) until the pH was 5 5 - 6.2. The resultant mixture was subjected to further vacuum distillation at 94 81 kPa (28 inches Hg) and 80°C to reduce the water content thereof to <2 5% The viscosity of this hybrid resin was 1800 - 2800 mPa s (cPs) at 25°C 0 The physical characteristics ofthe above hybrid resin are tabulated below in Table 6 and is compared with the properties of conventional resins In the data provided, the reference to 10% Siloxane relates to the amount of Siloxane in the final product, in the case of Example 5 after removal of water by vacuum distillation 5 TABLE 6

* - This is a comparative test (not according to the invention) in which the initial phenol-aldehyde resin of Example 5 (base resin) was mixed with 10% siloxane and a catalyst but without heating the resultant mixture of reducing the water content

20 thereof

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