NL2006218C2

NL2006218C2 - A method for reducing the formaldehyde content of a resinous starting material.

Info

Publication number: NL2006218C2
Application number: NL2006218A
Authority: NL
Inventors: Gerardus Wilhelmus Schuren
Original assignee: Trespa Int Bv
Priority date: 2011-02-16
Filing date: 2011-02-16
Publication date: 2012-08-24
Also published as: WO2012112043A1

Description

A method for reducing the formaldehyde content of a resinous starting material.

The present invention relates to a method for reducing the formaldehyde content of a resinous starting material. In addition, the present invention relates to the use 5 of such a resinous material as well as to a panel comprising resin impregnated cellulose fibers.

US patent No. 4,116,921 relates to a resin to be used in the production of moulded products. According to said document, such resins are characterized by a relatively narrow molecular weight distribution and low molecular weight, wherein the 10 polydispersity of such resins is low. The polydispersity ranges from about 1.5 to about 5, in particular from about 1.7 to about 3. Said document furthermore indicates that the duration of the reaction is determined by the desired polydispersity.

International application WO 01/46101 relates to so-called stable bisphenol compositions, which are used in usual lamination processes.

15 US patent No. 4,337,334 relates to the preparation of a phenol resin, wherein the phenol component comprises the group of high molecular weight phenolic compounds, which latter compounds are obtained as by-products in the preparation of bisphenol A.

Several publications relate to the reduction of the formaldehyde content 20 in resins, e.g. EP 0 148 050, EP 0 480 778, US 6 114 491.

A phenol resin that is mentioned in the introduction is known per se from International application WO 91/19749, which has the same inventor as the present application. According to said International application, the molecular structure of the phenol resin obtained as a result of the reaction must meet a number of requirements, 25 using a special ratio of the total number of reactive sites (A) in the phenol resin to the total number of sites (B) in the phenol resin to which formaldehyde is added, to the total number of sites (C) in the phenol resin in which two molecules of the phenolic compounds are condensed with each other through a methylene group, which ratio is as follows: (A):(B):(C)=1 :(0.85 to 1.0):(less than or equal to 0.05, in particular less than or equal to 30 0.02).

2 0 0 6 2 1 8 2

From International application WO 01/74750 there is furthermore known a mixture which is used in the preparation of phenol resins, epoxide resins or formaldehyde resins, which starting mixture contains 35 to 75 wt.% of p,p-bisphenol A, 5 to 25 wt.% of o,p-bisphenol A and 20 to 50 wt.% of secondary products which are 5 produced during the preparation of bisphenol A, wherein the sum of the proportions by weight of p,p-bisphenol A and o,p-bisphenol A is 50 to 80 wt.% and wherein the sum of the proportions by weight of p,p-bisphenol A and o,p-bisphenol A and the secondary products is 100 wt.%. In particular, the mixture additionally contains 0 to 90 wt.% of phenol, with respect to the total weight of the mixture then produced. Further details with 10 regard to the phenol resin prepared with said starting material are not provided in said document, not to mention the specific requirements that are made of a phenol resin used in the production of rigid moulded products.

US 2008/0085968 relates to molding compositions, in particular to thermoplastic molding compositions which comprise polyoxymethylene polymer, 15 zeolitic material and thermoplastic polyurethanes. The use of zeolitic material as a constituent of a polyoxymethylene-containing molding composition is to reduce formaldehyde emission.

EP 0 619 344 relates to acetal resin composition comprising specific oxymethylene copolymers, hindered phenol type antioxidants, and ion 20 adsorbents. The acetal resin compositions are capable of avoiding the formation of mold deposits and the smell of formaldehyde gas during mold.

JP 2008 260923 relates to a polyacetal resin composition which is excellent in the low formaldehyde emissions and thermal stability.

JP 2006 181537 relates to a formaldehyde gas treatment agent or 25 coating material excellent in formaldehyde adsorption capability and formaldehyde selectivity. The formaldehyde gas treatment agent contains a composite metal hydroxide.

US 6,590,020 relates to thermoplastic polyoxymethylene molding materials containing from 10 to 99.98% by weight of a polyoxymethylene homo- or 30 copolymer and may contain further conventional additives and processing assistants, such as formaldehyde scavengers, plasticizers, adhesion promoters and pigments in an amount of from 0.001 to 5% by weight.

WO 96/34041 relates to a molded article of a resin composition obtained by adding a specific amount of a solid solution of a specific magnesium 3 oxide and aluminum oxide to a polyoxymethylene resin. These molded articles from the polyoxymethylene resin composition can be used in gears, chassis, cams, rollers, and the like.

The present inventors found that the presence of formaldehyde in a 5 resinous material will result in the emission of unwanted components when the resinous material has been used in the manufacturing of for example construction materials, like HPL (high pressure laminates) panels. In addition, the release of formaldehyde during its production in the factory should be kept as low as possible, due to safety and health requirements.

10 The object of the present invention is to provide a method for reducing the formaldehyde content of a resinous starting material such that it is possible to reduce the formaldehyde content significantly without adversely effecting the physical characteristics of the resinous material itself.

Another object of the present invention is to provide a method for 15 reducing the formaldehyde content of a resinous starting material such that it is possible to obtain a resinous material without additional, unwanted chemicals, especially so-called formaldehyde scavengers.

Another object of the present invention is to provide a resinous material having a very low formaldehyde content, especially a formaldehyde content below the 20 detection limit of the chemical analytical method used when filing the application.

According to the present invention, the method for reducing the formaldehyde content of a resinous starting material comprises the steps of: a) providing a resinous starting material having a formaldehyde content in the range of from 0.01 wt.% to 25 wt.%., and b) subjecting said resinous starting 25 material to a contact process in the presence of a heterogeneous catalyst such that the formaldehyde of the resinous material thus treated is lower than the formaldehyde content of the resinous starting material, preferably in the range of from 5 wt.% to 0 wt.%.

Using such a method, it is possible to achieve one or more of the aforesaid objects. The lower limit of 0 wt.% should be interpreted as the detection limit of 30 the at present available analytical methods. This means that according to the present method the formaldehyde content of the resinous starting material can be reduced below the detection limit of the analytical apparatus. In practice, such a low content of formaldehyde does not necessarily means zero weight percent, but its content is in the range of several ppms.

4

The present invention is not restricted to a method in which the formaldehyde content of the resinous material treated is always below an amount of 5 wt.%, but the present method shows that a reduction of the formaldehyde content in a resinous starting material can be obtained in an effective way by using a heterogeneous 5 catalyst.

The present method clearly shows that the formaldehyde content can be reduced without the incorporation of additional chemicals, like formaldehyde scavengers. Therefore, in a preferred embodiment the present invention clearly disclaims the use of those chemicals, e.g. urea, melamine, primary and secondary amines and other amine 10 based modifications. Disadvantages of these scavengers are, among others, odor problems, precipitation, crystallization and reduced pot life of the resin.

The heterogeneous catalyst according to the present invention is preferably of the alkaline type. According to a preferred embodiment the heterogeneous catalyst according to the present invention consists of alkaline metal oxides and/or 15 hydroxide or of mixtures thereof, or of alkaline solid inorganic materials, e.g. N-doped carbon nanotubes, ion exchangers).

More preferably the heterogeneous catalyst consist of oxides and/or hydroxides of elements or mixtures of elements from the first group of the Periodic Table, also referred to as alkali metals, consisting of the elements lithium, sodium, potassium, 20 rubidium, caesium, and francium or of elements or mixtures of elements of the second group of the Periodic Table, also referred to as earth alkali metals, consisting of the elements beryllium, magnesium, calcium, strontium, barium, and radium or of elements or mixtures of elements of the third group of the Periodic Table, also referred to as rare earth metals, consisting of the elements scandium, yttrium, lanthanum, and actinium or of 25 elements or mixtures of elements ranging from order number 58 to 71 of the Periodic Table, also referred to as lanthanides, consisting of cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium or of elements or mixtures of elements of the Group four of the Periodic Table, consisting of titanium, zirconium, and hafnium or of elements or 30 mixtures of elements of the Group eleven of the Periodic Table, consisting of copper, silver, and gold or of elements or mixtures of elements of the Group twelve of the Periodic Table, consisting of zinc, cadmium, and mercury or of mixtures thereof like for example spinels; either in pure form (eg. CuAI204, ZnAI204, MnAI204), as mechanical mixtures of different spinels or as mixed spinels (eg. (Cu)x(Zn(1-x))AI204); perowskits, or layered 5 double hydroxides (LDH).

Even more preferably the heterogeneous catalyst according to any of the preceding claims consists of oxides and/or hydroxides of lithium, sodium, potassium, beryllium, magnesium, calcium, barium, lanthanum, cerium, zinc, zirconium, and copper 5 or mixtures thereof like for example spinels; either in pure form (eg. CuAI204, ZnAI204, MnAI204), as mechanical mixtures of different spinels or as mixed spinels (eg. (Cu)x(Zn(1-x))AI204); perowskits, or layered double hydroxides (LDH).

The earth alkali metal is monovalent or divalent, preferably divalent.

The earth alkali metal is preferably derived from the group of oxides, 10 hydroxides, carbonates, sulfates, and phosphates or any other anorganic earth alkali metal salt, or from the group of organic earth alkali metal salts consisting of formates, acetates, oxalates, stearates, or of mixtures thereof.

Preferably the earth alkali metal is derived from oxides, hydroxides, carbonates, sulfates, phosphates or mixtures thereof.

15 More preferably the earth alkali metal is derived from oxides, hydroxides, carbonates or mixtures thereof.

Another embodiment of the invention uses as a heterogeneous catalyst the alkaline metal oxides and/or hydroxides or mixtures thereof supported on a carrier material/substrate.

20 In more detail the carrier material/substrate is selected from the group of anorganic matrices consisting of aluminum oxide, silicon oxide, silicon-aluminum oxide, titanium oxide, zirconium oxide, bauxite, clays, pumice, activated carbon, carbon nanotubes, molecular sieves or from the group of organic matrices consisting of polymers, and polymeric resins.

25 Typical surface areas are 2-400 m2/g: preferably 10-250 m2/g.

The present catalyst can be used in the form of powders, flakes, spheres, pellets, rings, extrudates or in any other suitable form. The catalyst particles may be used in a wide range of dimensions, for instance, as pellets with a diameter of 1-5 mm or as powders whose particles have a grain size of 15-35 mesh (largest diameter of 30 approx. 13-0.5 mm), 30-80 mesh (largest diameter of approx. 0.595-0.177 mm) or 100-325 mesh (largest diameter of approx. 0.15-0.04 mm). In general, the catalytic process proceeds faster as the catalyst particles are smaller.

The resinous starting material as mentioned in step a) above is chosen from the group of melamine, urea and phenolic based resins, or combination thereof, 6 preferably phenol based resins are used.

The present inventors found that the temperature in step b) is preferably in the range of 0 -110 °C.

In the embodiment of a continuous process, the liquid hourly space 5 velocity (LHSV) in step b) is in the range of 0.1 - 20, preferably in the range of 0.3 -10, more preferably 0,5 - 5 [1/h]..

In the embodiment for a batch process the residence time in step b) is preferably in the range of 10-500 minutes, preferably less than 200 minutes. The present inventors found in a special embodiment that the reaction time is influenced by the 10 formaldehyde content of the resinous starting material and the amount of catalyst applied. Therefore, the residence time can be as long as 400 minutes when high contents of formaldehyde are present in the resinous starting material especially when the formaldehyde content is to be reduced as low as < 0.05 wt.%.

The present inventors found that the resinous starting material as used 15 in step a) is preferably a mixture of two or more of the group of phenol and its derivates, bisphenol F and its derivatives, bisphenol A and its derivatives, triphenols, tetraphenols, chromanes, indanes, substituted or non-substituted phenols, and polyphenols.

The resinous starting material has preferably a weight average molecular weight (Mw) of 123-1000, preferably 300-600, and the resinous material 20 obtained after step b) has preferably a weight average molecular weight (Mw) of 150-750, preferably 350-600.

The present inventors found that according to the method according to the present invention, the weight average molecule weight (Mw) ratio of the resinous starting material and the resinous material thus treated is in the range of 0.75-1.50. Such 25 a range is an indication that the physical properties of the resinous material have not been changed dramatically after carrying out the method according to the present invention.

The term “polydispersity” as used in the present description is a dimensionless parameter, which is known to those skilled in the art and which is defined as the quotient of the average molecular weight, Mw, and the molecular mass that 30 comprises the largest number of molecules, Mn, viz. MJMn. The ratio Mw/Mn can be considered to be the width of the molecular weight distribution obtained through a GPC method. If a phenol resin having a polydispersity outside the aforesaid range is used, an unsatisfactory impregnation behaviour will be observed, in particular in the case of heavier papers, which has an adverse effect, e.g. on the distribution of the resin in a moulded 7 product formed of impregnation paper, and which is thus disadvantageous with regard to the mechanical properties and the hygric values thereof.

In a preferred embodiment of the present invention the polydispersity of the resinous starting material is 1.0-3.0, wherein the polydispersity of the resinous 5 material obtained after step b) is 1.0-3.0.

According to the present method the present inventors found that the polydispersity ratio of the resinous starting material and the resinous material thus treated is in the range of 0.75-1.5.

In the present invention step b) can be carried out as a continuous 10 process, wherein the reactor is chosen from the group of tubular reactor, cascade reactor and/or plug flow reactor type, or a combination thereof. According to another embodiment the present method can be carried out as a batch process, e.g. in a batch reactor in which temperature and residence time can be controlled very accurately.

According to a preferred embodiment of the present invention the 15 resinous material obtained after step b) is subjected to a step c), in which step c) comprises an additional treatment for reducing the amount of residual heterogeneous catalyst in said resinous material to a minimum, preferably neutralization, filtering, separation or a combination thereof.

Furthermore, it is possible in a preferred embodiment to add one or 20 more additives to the resinous material before or after either of step b) or step c), in which said additives are chosen from the group of flame retardants, stabilizers, pigments, dispersion agents, antistatics, flow modification agents, solvents, curing agents. The exact moment of adding the additives depends on the chemical character of the additives. Care should be taken that the heterogeneous catalyst is not poisoned by any of the additives.

25 The resinous material obtained according to the method of the present invention can be used for impregnating inert parts, especially impregnation paper, in which the thus impregnated paper can be used for the assembly of panels. The process for manufacturing panels as such is known from US 4,927,572, US 4,789.604, which documents are in the name of the present applicant and can be incorporated here as 30 reference.

The resinous material obtained according to the present invention is especially suitable for an impregnation paper having a weight of at least 40 g/m2, especially in the range of 120-400 g/m2.

The present invention further relates to a panel comprising a resin 8 impregnated cellulose fiber, wherein the resinous material is obtained according to the present method. In a special embodiment the resinous material is a phenolic based resin. According to a special embodiment the present panel meets the requirements of F**** (four star rating) according to JIS A 4 XXX.

5 In addition, the present method relates to a resinous material obtained according tot the present method, in which resinous material the formaldehyde content is in a range of 3 wt.%-0 wt.%, preferably less than 0.05 wt.%, in which resinous material preferably no formaldehyde scavengers are present. As mentioned before, according to the present method the formaldehyde content of the resinous starting material can be 10 reduced below the analytical detection limit of the analytical apparatus used, e.g. a potentiometric method.

In order to provide a better understanding of the invention, the present invention will now be explained by means of a number of examples, in which connection it should be noted, however, that the present invention is by no means limited to such 15 special examples.

The method for determining the weight average molecular weight is based on GPC. The method for determining the free formaldehyde content in a resin is based on a potentiometric method. According to the potentiometric method a sample of the resin is solved in a mixture of iso propanol and water. Hydroxyl ammonium chloride as 20 a reagens is added and a reaction between said reagens and formaldehyde will result in the formation of acid. The amount of acid thus formed is determined by adding aqueous potassium chloride.

Examples

Example 1A

25 A 20 °C preheated 0.5 liter double-walled laboratory batch reactor equipped with an overhead stirrer and a reflux condenser is charged with 360 g of a Phenol Resol type impregnation resin. 15-20 g of the resin are taken as zero time sample. Under moderate stirring 40 g of the heterogeneous catalyst Pural MG 70 (see table III for its composition) are added to the preheated resin. The temperature during the test is kept 30 at 20 °C by a thermostat. In regular interval times resin samples (15-20 g) are taken to analyse and monitor the chemical composition to detect specific changes in the composition. All samples are stored in a refrigerator to prevent further conversion until analysis.

9

Example 1B

The same steps as mentioned in Example 1A were carried out, except that the temperature increased to 30 °C.

Example 1C

5 The same steps as mentioned in Example 1B were carried out, except that the temperature increased to 50 °C.

Table I

Test__la__1b__1c_

10 Reaction temperatures in °C 20 °C 30 °C 50 °C

Sampling time from he beginning of Ö Ö Ö the test in minutes

Free formaldehyde content % m/m 0,93 0,93 0,93

Free phenol content % m/m 5.46 5.46 5.46 15 IVLavg. 523 523 523

Polydispersity 2.178 2.178 2.178

Sampling time from the beginning of 120 120 80 the test in minutes 20 Free formaldehyde content % m/m__0,44__0,27__0,67_

Free phenol content % m/m 5.38 5.52 5.46

Mv, avq. ~ 513 ~ 497 510

Polydispersity 2.085 2.101 2.124

Sampling time from the beginning of 240 240 160 25 the test in minutes

Tree formaldehyde content % m/m <0,05 <0,05 0,25

Free phenol content % m/m__5.38__5.46__5.32_ M*avg. 493 472 491

Polydispersity 2.036 2.053 2.083 30

Table II

10

Test 2a 2b

Resin type BPA resol PF resol 5 ____

Sampling time from on the 0 0 beginning of the test in minutes

Free formaldehyde content % m/m 1.42 0,93

Free phenol content % m/m 3.98 5.46 avg. 3Ï4 523 in----

Polydispersity 1.581 2.178

Sampling time from he beginning of 120 120 the test in minutes

Free formaldehyde content % m/m 0.50 0,27 he----

Free phenol content % m/m 3.99 5.52 M„ avg. 3Ö9 497

Polydispersity 1.572 2.101

Sampling time from he beginning of 24Ö 240 20 the test in minutes

Free formaldehyde content % m/m <0.05 <0,05

Free phenol content % m/m 3.96 5,46 M, avg. 306 ' 472

Polydispersity__1.565__2.053_ 25 A formaldehyde content <0.05% means below the detection limits of the analytical method. The results disclosed in Table II demonstrate that the BPA resol having a relative high free formaldehyde content of 1.42 % can be effectively reduced to a content of < 0.05% after a reaction time of 240 minutes.

' 30 11

Example 3A

A 30 °C preheated 0.5 litre double-walled laboratory batch reactor equipped with an overhead stirrer and a reflux condenser is charged with 360 g of a Phenol Resol type impregnation resin. 15-20 g of the resin are taken as zero time sample.

5 Under moderate stirring 40 g of the heterogeneous catalyst Nopro RO 365 (see table III for its composition) are added to the preheated resin. The temperature during the test is kept at 30 °C by a thermostat. In regular interval times resin samples (15-20 g) are taken to analyse and monitor the chemical composition to detect specific changes in the composition. All samples are stored in a refrigator to prevent further conversion until 10 analysis.

Example 3B

The same steps as mentioned in Example 3A were carried out except that catalyst Nopro RO 366 (see table III for its composition) was used.

Example 3C

15 The same steps as mentioned in Example 3A were carried out except that catalyst Pural MG30 (see table III for its composition) was used.

Example 3D

The same steps as mentioned in Example 3A were carried out except that catalyst Pural MG70 (see table III for its composition) was used.

20 Example 3E

The same steps as mentioned in Example 3A were carried out except that Bisphenol A mixture + Phenol Resol type impregnation resin was used as the resin.

Example 3F

The same steps as mentioned in Example 3C were carried out except 25 that Bisphenol A mixture + Phenol Resol type impregnation resin was used as the resin.

Example 3G

The same steps as mentioned in Example 3D were carried out except that Bisphenol A mixture + Phenol Resol type impregnation resin was used as the resin.

30 12

Table III

Tests 3a 3b 3c 3d 3e 3f 3g

Heterogeneous Nopro Nopro Pural Pural Nopro Pural Pural catalysts R0 365 R0 366 MG30 MG70 R0 365 MG30 MG70

Resin type PF PF PF PF BPA BPA BPA

5 resin resin resin

Sampling time from 0 0 0 0 0 0 on the beginning of the test in minutes 10 Free formaldehyde 0.88 0.80 0.82 0,93 1.21 1.20 1.42 content % m/ro

Free phenol content 5.41 5.44 5.42 5,46 3.95 3.96 3.98 % m/m

Mw avg. 583 588 589 523 374 368 3Ï4

Polydispersity 1.918 1.924 1.936 2.178 1.475 1.461 1.581 15 --------

Sampling time from 240 240 240 240 240 240 240 on the beginning of the test in minutes

Free formaldehyde Ö33 ÖÖ6 Ö42 <005 032 084 <005 „ content % m/m 20________

Free phenol content 5.24 5.19 5.41 5.46 3.79 3.70 3.96 % m/m

Mw avg. 536 527 6Ö4 472 356 37Ö 3Ö6

Polydispersity T823 Ï322 Ï954 2.053 ÏT43Ï T46Ï Ï165

Remarks: 25 Pural Mg 70 = 70 wt.% MgO and 30 wt.% AI2O3 Pural Mg 30 = 30 wt.% MgO and 70 wt.% AI2O3 RO 365 282 = 23.2 wt.% MgO and 76.8 wt.% AI2O3 RO 366 283 = 19.4 wt.% MgO, 36.4 wt.% CaO, 41.9 wt.% AI2Q3 and 2.05 wt.% SiP2_ 30 13 A formaldehyde content <0.05% means below the detection limits of the analytical method.

The results disclosed in Table III demonstrate that the efficiency for removing the formaldehyde content can be increased upon increasing the content of Mg.

5 In addition, the results also show that a mixture of different types of phenol components having a relatively high formaldehyde content can be treated in an effective way by the method according to the present invention.

10 2006218

Claims

A method for reducing the formaldehyde content of a resinous starting material, characterized in that the method comprises the following steps: a) providing a resinous starting material with a formaldehyde content in the range of 0.01% by weight to 25 wt%, and b) subjecting the resinous starting material to a contacting process in the presence of a heterogeneous catalyst such that the formaldehyde content of the resinous material thus treated is lower than the formaldehyde content of the resinous starting material, preferably in the range of 5 % by weight to 0% by weight.

Process according to claim 1, characterized in that the heterogeneous catalyst is of the alkaline type.

Process according to one or more of claims 1-2, characterized in that the heterogeneous catalyst comprises one or more of alkali metal oxides, alkali hydroxides and alkali-solid inorganic materials, wherein the alkali metals are preferably selected from the first group and / or or second group of the Periodic System, in particular preferably selected from the group of oxides and / or hydroxides of lithium, sodium, potassium, beryllium, magnesium, calcium, barium, lanthanum, cerium, zinc, zirconium and copper or mixtures thereof , in particular magnesium oxide and / or calcium oxide.

Method according to one or more of the preceding claims, characterized in that the resinous starting material is selected from the group of melamine, urea and phenol-based resins, or combinations thereof.

Method according to one or more of the preceding claims, characterized in that the temperature in step b) is in the range of 0-110 ° C.

6. Process according to one or more of the preceding claims, characterized in that the heterogeneous catalyst is applied to a support, preferably selected from one or more of the group of inorganic matrices consisting of aluminum oxide, silicon oxide, silicon-aluminum oxide, titanium oxide, zirconium oxide, bauxite, clay materials, pumice, activated carbon, carbon nanotubes, molecular sieves or of the group of organic matrices consisting of polymers and polymer resins, in which the support preferably has an area in the range of 2-400 m2 / g, in particularly in the range of 10-250 m2 / g. 2006218

Method according to one or more of the preceding claims, characterized in that the residence time in step b) is in the range of 10-500 minutes, preferably less than 200 minutes, for a batch process.

8. Method according to one or more of the preceding claims, characterized in that the resinous starting material is a mixture of two or more of the group of phenol and its derivatives, bisphenol F and its derivatives, bisphenol A and the derivatives of these, triphenols, tetraphenols, chromane compounds, indane compounds, unsubstituted or substituted phenols and polyphenols.

9. Method according to one or more of the preceding claims, characterized in that the resinous starting material has a weight average molecular weight (iv1w) of 123-1000, preferably 300-600.

Method according to one or more of the preceding claims, characterized in that the resinous material obtained after step b) has a weight average molecular weight (Mw) of 150-750, preferably 350-600.

Method according to one or more of the preceding claims, characterized in that the ratio of the weight average molecular weight (Mw) of the resinous starting material and the resinous material thus treated is in the range of 0.75-1.50.

12. Method according to one or more of the preceding claims, characterized in that the polydispersity of the resinous starting material is 1.0-3.0.

Method according to one or more of the preceding claims, characterized in that the polydispersity of the resinous material obtained after step b) is 1.0-3.0.

14. Method according to one or more of the preceding claims, characterized in that the ratio of polydispersity of the resinous starting material to the resinous material thus treated is in the range of 0.75-1.5.

Process according to one or more of the preceding claims, characterized in that the formaldehyde content of the resinous starting material is at most 10% by weight, preferably at most 5% by weight, in particular at most 2.5% by weight , in particular preferably not more than 0.5% by weight.

Process according to one or more of the preceding claims, characterized in that step b) is carried out as a continuous process, wherein the reactor is selected from the group of tubular reactor, cascade reactor and / or plug flow type reactor, or a combination thereof. O

Method according to one or more of the preceding claims, characterized in that the resinous material obtained after step b) is subjected to a step c), wherein step c) comprises an additional treatment for reducing the amount to a minimum residual heterogeneous catalyst in the resinous material, preferably via neutralization, filtering, separation or a combination thereof.

Method according to one or more of the preceding claims, characterized in that one or more additives are added to the resinous material before or after step b) or c), wherein the additives are selected from the group of flame retardants, stabilizers , pigments, dispersants, antistatic agents, flow modification agents, solvents, curing agents.

Use of a resinous material according to one or more of claims 1-18 for the manufacture of panels obtained by impregnating inert parts, in particular impregnation paper, with the resinous material and subsequently compressing the assembly of resin-impregnated resin inert parts under conditions of elevated temperature and pressure to obtain the panels.

Use of a resinous material according to claim 19, wherein the impregnation paper has a weight of at least 40 g / m2, in particular in the range of 120-400 g / m2.

21. Panel comprising cellulosic fibers impregnated with resin, characterized in that a resinous material obtained according to one or more of claims 1-18 is used.

Hieroglyphic material obtained according to one or more of claims 1 to 18, characterized in that the formaldehyde content is in the range of 3% by weight to 0% by weight, preferably less than 0.05% by weight, in which resinous material no formaldehyde scavengers are present.

Resin-like material according to claim 22, characterized in that no formaldehyde scavengers are present. 30 2006218