DD273639A1 - PROCESS FOR THE PREPARATION OF DICYCLOPENTADIALLY-MODIFIED PF RESOLES - Google Patents

Abstract

The invention relates to a process for the preparation of dicyclopentadiene-modified PF resoles, which can be further processed into flame-retardant decorative or Elektroisolierschichtpressstoffen or molding compounds. The aim of the invention is a cost-effective, in the existing systems of PF resin producers feasible process for the production of high quality PF resoles that lead to PF materials with good dielectric characteristics, low water absorption, high dimensional stability, good heat resistance. The object of the invention is the preparation of dicyclopentadiene-modified PF resoles, in which by adding dicyclopentadiene or a dicyclopentadiene concentrate to the phenolic raw material at room temperature and subsequent heating to 313 to 403 K, this is alkylated until complete reaction of the DCPD. The object is achieved in accordance with the invention by reacting phenol and / or its homologues with dicyclopentadiene or dicyclopentadiene concentrate in the presence of an acid as catalyst at 313 to 403 K in a first process stage. Subsequently, the resin condensation is carried out with formaldehyde and a basic catalyst.

Description

LEWIS acid is reacted as a catalyst in a temperature range of 313 to 403K, preferably 353K. The DCPD concentrate is a readily available and inexpensive raw material from petroleum chemistry with about 85% presensitizable constituents, with a DCPD content of at least 65%. The mass ratio PhenohDCPD is between 1: 0.1 to 1.0, preferably 1: 0.2. The molar ratio of phenolic raw material catalyst is between 1: 0.001 to 0.1, preferably 1: 0.05. As phenolic raw materials it is possible to use preferably phonol, but also all other compounds customary for the preparation of PF resoles, including cresols, alkyl and alkenyl phenols, cashew nut shell oil and mixtures of these compounds. After the alkylation reaction, formaldehyde and a basic catalyst are added to the batch, followed by resin condensation. The molar ratio of phenol to formaldehyde basic catalyst is 1: 0.8 to 1.6: 0.01 to 0.2, preferably 1: 1.1: 0.1. Particularly suitable catalysts are amines and ammonia, but it is also possible to use all other basic catalysts known for the preparation. The DCPD-modified PF resins obtained after distillative dehydration are dissolved in conventional aliphatic alcohols and other common solvents, e.g. dissolved in a mixture of methanol / toluene or they are mixed with organic and / or inorganic fillers and processed into molding compositions. The resins dissolved in solvents may contain, as further modifying components, triaryl phosphates and / or aryl-alkyl phosphates and / or flame retardants (eg tetrabromdiane, red phosphorus) and / or low molecular weight PF resoles and / or amino resins in a mass ratio DCPD-modified PF Resole: Modification components of 100: 5 to 60 are added. The DCPD-modified PF resin solutions prepared by the process according to the invention can be used for the impregnation of flat support materials, in particular cellulose fabrics and papers. Elastic insulating laminates produced on this basis are characterized by good dielectric properties, high dimensional stability, high heat resistance and good tracking resistance. If the modified PF resin solutions are used to produce the core papers for the production of high-quality decorative laminates, these laminates are characterized by good mechanical properties, low water absorption and high heat resistance. It was not expected that an alkylation mixture of phenol and DCPD or DCPD concentrate prepared by the described method would be suitable for producing high quality PF material ion. It is known that arise in the acid-catalyzed reaction of phenol and DCPD in addition to nuclear alkylated products and phenol ethers. The extent of ether formation depends on the molar ratios and the reaction temperature. A higher DCPD content and lower reaction temperatures favor phenol ether formation. It is further known that phenol ethers do not react with formaldehyde under resol production conditions, ie they are not included in the condensation process. It has been demonstrated that phenol ethers are formed in relatively large amounts by the process according to the invention. Nevertheless, obtaining PF resins which after curing result in a regular network structure with high dimensional stability and good heat resistance can be explained by the fact that the DCPD which has reacted with the norbornene ring double bondone in the alkylation with phenol is attached to the second, less reactive double bonds with hydroxymethyl groups of the PF resin in reaction and thus contributes to a regular three-dimensional crosslinking

 The method according to the invention will be explained in more detail with reference to exemplary embodiments:

embodiments

Example 1:

3.5 kg of p-toluenesulfonic acid are dissolved in 470 kg of phenol. Then add 150kg of DCPD concentrate and heat to 353K. At this temperature allowed to react for 60min. The reaction mixture contains no free DCPD. ' After filling with 415 kg of formalin (37%) and 34 kg of ammonia (25% aqueous solution), the resin condensation is carried out under reflux for 80 min. After distilling off the water, 200 kg of tricresyl phosphate, 150 kg of methanol and 100 kg of toluene are added.

As flame retardant Tetrabromdian (6kg per 100kg resin solution) is used.

Festharzkennwurte: B time 6, [> min free form 11% free form aldehyde 1% Resin solution: B time 12.7 min viscosity at 293K 31OmPa-S Solids content 58%

When using this resin solution for impregnating already prepregged sodium kraft paper, the following properties are determined on the electro-insulating laminate:

characteristic value standard determined UL 94 test (afterburn time s / level) <50 / VO 20 / VO Elemental Analysis (Br / P) - 2.4 / 1.3 Curvature (mm) (after 30 min at 423 K) S1 0.5 Shrinkage (after 30 min at 423 K) (longitudinal / transverse χ 10 ² %) 5 ± 3/9 ± 4 5.8 Water absorption (%) <0.75 0.34 dielectric loss factor <0.05 0.03 Solder bath resistance (s) (at 533 K) > 10 60

Example 2:

3.5 kg of p-toluene sulfonic acid are dissolved in 470 kg of phenol. Subsequently, 200 kg of DCPD concentrate are added. After heating to 353 K, SO min is allowed to react at this temperature. Then 415 kg of formalin (37%) and 60 kg of a 33% aqueous sodium hydroxide solution are added and the resin is reacted for 90 min under reflux. By adding a neutralizing agent solution consisting of 50% by mass of 37% hydrochloric acid and 50% by mass of ethanol, the resin is adjusted to a pH of 8.0 and then subjected to vacuum distillation. The solid resin is dissolved in 250 kg of methanol and mixed with 80 kg of red phosphorus.

Solid resin characteristics: B time 5.7 min free phenol 6% free form aldehyde <1% Resin solution: B time 7.6 min viscosity bni 293 K 34OmPa-S Feitkörpergehalt 63%

When the PF resin solution is used for the production of core papers for decorative laminates, high quality composites meeting the specifications specified in standard sheets and having high dimensional stability and heat resistance are obtained.

Claims (3)

1. A process for the preparation of dicyclopentadiene-modified PF resoles in which an alkylation of the phenolic raw materials with dicyclopentadiene is carried out, wherein the alkylation catalyst is a BRÖNSTEDT or LEWIS acid is used, characterized in that phenol and / or its homologues already at room temperature with the catalyst and the dicyclopentadiene; and alkylated in a temperature range of 313 to 483K, the proportion of phenothiyclopentadiene being 1: 0.1 to 1.0, followed by reaction with formaldehyde and a basic catalyst in proportions of phenol: formaldehyde Catalyst equal to 1: 0.8 to 1.6: 0.01 to 0.2. 2. The method according to claim 1, characterized in that instead of DCPD a DCPD concentrate with about 85% resinable constituents, as obtained in the distillation of the C5 fraction in petal chemistry, is used. 3. The method according to claim 1, characterized in that "as phenolic raw materials in addition to phenol, all other customary for the preparation of PF resoles compounds including cresols, alkyl and alkenyl phenols, Gashewnußschalenöl and mixtures of these compounds are used. Field of application of the invention The invention relates to a process for the preparation of DicyclopentadienlDCPDl-modifiable PF resoles, which can be processed into flame-retardant decorative or Elektroisolierschichtpreßstoffen or in molding material, these products are characterized by a low water absorption, good dielectric properties, high dimensional stability and good heat resistance. Characteristic of the known technical solutions In many applications, unmodified PF resins no longer meet today's high material requirements. Unmodified PF resins provide materials with high stiffness, high water absorption, poor dielectric properties, and inadequate dimensional stability. To overcome these disadvantages, numerous modification possibilities have been developed. Success is, for example, the incorporation of bisphenols, especially bisphenol A or adducts of phenol with isopropenylphenol or the modification with low molecular weight EP resins. Such methods, however, are very expensive due to these raw materials. A number of patents (U.S. Patent No. 3,583,052) disclose methods of modifying PF resins with DCPD. This modification with DCPD leads to a reduction in water absorption, an increase in solvent resistance and an improvement in the dielectric and mechanical properties. In addition, DCPD in the form of a concentrate (about 85% resinable constituents) is obtained as a by-product in petal chemistry and therefore has a favorable price compared to phenolic raw materials. However, these methods have a procedural disadvantage that first phenol must be mixed with sulfuric acid and heated to 403 K and therefore the slow dropwise addition of the DCPD concentrate. The procedure is complex in terms of apparatus and time and leads to a significant increase in costs. By choosing these reaction conditions it is achieved that phenol is always present in large excess and that the reaction between DCPD and phenol takes place predominantly at the core positions of the phenol and not on the phenolic hydroxyl group. While core-alkylated phenols react with formaldehyde in the resin condensation and are thus incorporated into the PF resin, phenol ethers do not react under these reaction conditions. This apparent advantage, however, comes with a further disadvantage; At the selected fairly high temperatures, a reaction of the DCPD in cyclopentadiene already takes place. Forming cyclopentadiene reacts with a DIELS-ALDER reaction with dicyclopentadiene to form cyclopentadiene oligomers, which, although fully reactive with phenol, allow for a retro-DIELS-ALDER reaction in the cured PF resin at elevated temperatures. The result is that products based on such DCPD-modified resins have insufficient heat resistance for many applications. Object of the invention It is the object of the invention to develop a low-cost, realizable in existing systems of PF resin producers process for the production of high-quality PF resoles that can be processed into flame-retardant decorative or Elektroisolierschichtpreßstoffen or in molding compositions that are characterized by a low water absorption, good dielectric? Characteristics, high dimensional stability and good heat resistance. Explanation of the essence of the invention The object of the invention is the preparation of DCPDi, modified PF resoles, in which by the addition of DCPD or a DCPD concentrate to the phenolic raw material at room temperature and subsequent heating to 313-403K this is alkylated until complete reaction of the DCPD. The object of the invention is achieved by the fact that in a first process stage phenol and / or its homologues with DCPD or DCPD concentrate in the presence of a BRÖNSTEDT or