DE1057331B - Heat-curable molding, coating and adhesive based on epoxy resin - Google Patents

Description

GERMAN

KJL. S ^ JO ΔΔΙΧ.Ό

INTERNATIONAL KL.

PATENT OFFICE C08g; C09f; j

N 14051 IVb / 39 b

REGISTRATION DATE: AUGUST 28, 1957

NOTICE
LOGIN
AND ISSUE OF THE
EDITORIAL: MAY 14, 1959

There are already thermosetting compositions made of an epoxy resin and a phenol aldehyde resin, such as one Novolak resin has been described whose heat curing by the addition of an alkaline reacting catalyst, in particular an alkali hydroxide or alkali phenolate or an amine can be. Such catalysts are effective even at room temperature. It finds a slow hardening reaction takes place, so that the mixtures containing the catalyst are not stable in storage but have to be processed fairly quickly.

It has now surprisingly been found that this disadvantageous property can be avoided if as a thermosetting molding, coating and adhesive, a mixture of an epoxy resin with an average more than one epoxy group in the molecule and at least 0.1 epoxy equivalents per 100 g of resin and a thermoplastic phenol aldehyde condensate (novolak resin) having an average of at least two so phenolic hydroxyl groups in the molecule, or a \ ^ orkondensationsprodukt from the epoxy resin and the novolak resin, and the alcoholate or salt of a polyvalent metal, the salt of a higher molecular weight optionally unsaturated fatty acid, a resin acid or a ketoenol tautomer Connection, e.g. B. ethyl malonate or ethyl acetate is derived. Such thermosetting Masses are not reactive at room temperature, and they can therefore be practically unlimited Time to be stored. This is particularly important for the production of press powders, which are to be used in a company other than the manufacturing plant and are now ready for use can be delivered without the risk of premature hardening.

Although it was known for example from British patents 722 045, 722 154 and 729 258, that the metal compounds used in the context of the present invention for curing epoxy resins are suitable on their own, it was surprising that such metal compounds are also excellent. Catalysts for the reaction between epoxy resins and novolaks represent, as it is this is a completely different reaction mechanism.

Compared to these, the molding, coating and adhesive compositions according to the invention have known mixtures from pure epoxy resins and metal compounds the advantage that the cured masses a show higher heat resistance and solvent resistance. The first property mentioned is particular in the processing of pressed powders of importance, as generally takes about 10 minutes Thermosetting molding, coating and adhesive based on epoxy resin

Applicant:

NV De Bataafsche Petroleum
Maatschappij, The Hague

Representative: Dr. K. Schwarzhans, patent attorney,
Munich 19, Romanplatz 9

Claimed priority:
Netherlands 30 August 1956

Pieter Bruin, Amsterdam (Netherlands),
has been named as the inventor

is pressed at a temperature of 150 ° C and then too soft products present difficulties.

High heat resistance is also beneficial for processing as casting resins and for gluing. For example showed one obtained by reacting 2,2-bis- (4-oxyphenyl) propane with epichlorohydrin Epoxy resin with an average of 1.85 epoxy groups in the molecule, an epoxy equivalent of 0.5 / 100 g resin and a molecular weight of 370 after curing with cobalt oleate for 24 hours 140 ° C a heat distortion temperature of 75 ° C (measured according to ASTM D 648/264 Psi). From the However, later embodiments show that the products according to the invention after hardening Have heat distortion temperatures between 103 and 139 ° C. They can therefore be much better placed in In the form of molding powders, process as epoxy resins without the addition of novolak.

The better solvent resistance of the compositions according to the invention results from experiments in which paints made with it were treated for a few days by immersion in acetone. It didn't find any substantial softening takes place, while paints made from epoxy resins without a novolak additive already after softened for a few hours.

The epoxy resins to be used according to the invention are preferably obtained in a known manner by converting polyhydric phenols, such as 2,2-bis-

909 510/495

(4-oxyphenyl) propane, with epichlorohydrin or dichlorohydrin in an alkaline medium. These condensates are usually products containing molecules with the following specified structure contain:

CH ₂ -CH - CH ₂ - (O - R - O - CH ₂ - CHOH - CH ₂ ) "- 0 - R - 0 - CH ₂ - CH - CH ₃

In this formula, when the polyhydric phenol used is 2,2-bis- (4-oxyphenyl) -propane, R denotes a diphenylpropane radical, and η is either an integer or 0. The molecules can have alcoholic hydroxyl groups or to a greater or lesser extent Have phenolic groups. The corresponding bromine compounds can also be used in place of epichlorohydrin or dichlorohydrin. If desired, epoxy resins made from polyhydric alcohols such as glycerin can also be used

The epoxy resins to be used according to the invention generally contain no more than 0.8 epoxy equivalents per 100 g. The term "epoxy equivalent" here means the amount of epoxy resin in grams which contains 1 mole of epoxy groups.

The thermoplastic to be used according to the invention Phenol aldehyde resins are condensation products of alkylated or non-alkylated, monohydric or polyhydric phenols and aldehydes, preferably formaldehyde, which are known as' »Novolak« are known. Phenol and cresol are particularly suitable monohydric phenols which the desired. Novolak resins can be made.

The organic metal compounds to be used as curing catalysts according to the invention can be derived from aluminum, cobalt, or tin, for example.

The ratio in which the epoxy resin and the novolak resin are used according to the invention, can vary within wide limits. In general, per 100 parts by weight of epoxy resin 20 to 300 parts by weight of Nj volak resin is used. Preferably 30 to 120 parts by weight of novolak resin are applied to 100 parts by weight of epoxy resin. The larger the ratio of novolak resin to epoxy resin is. the higher the molecular weight of the novolak resin used.

The organic metal compounds are generally used in small amounts. Preferably According to the invention, 1 to 8%, very particularly preferably 1 to 4%, calculated on the weight of the epoxy resin, added to the mixture.

If desired, the mixtures according to the invention can also contain other constituents, such as pigments, Dyes and fillers.

The mixtures described above are hardened by heating. Suitable temperatures for this are between 80 and 220 ° C, in particular between 100 and 180 ° C. It is heated until the reaction product generated is insoluble and infusible. The duration of the heating depends on the curing temperature from, d. H. if higher temperatures are used, the curing time is shorter.

According to a technically particularly valuable embodiment, the mixture is before the formation of a insoluble and infusible reaction product to a. Cooled temperature lower than the temperature at which a reaction takes place, e.g. B. below 50 ° C. In this way, so-called Obtain precondensates, which are very valuable for a number of purposes.

In a subsequent work step, these precondensates can be heated to a temperature of

ίο 100 to 250 ° C in insoluble and infusible products being transformed. If desired, the metal compounds can also be a precondensation product from the epoxy resin and the novolak resin.

By grinding the in the introductory description Pre-condensates obtained in this way can be produced in a molding powder that differs from the known molding powders have various beneficial properties. In contrast to the known thermosetting powder, for example based on urea formaldehyde, melamine formaldehyde or phenol-formaldehyde resins, are used during heating in the deformation of the aforementioned precondensates no volatile components such as water or ammonia separated. So if these precondensates are used as molding powder, can be much lower pressures and therefore a more economical one The way of working can be used as when using the previously known press powder.

The mixtures containing precondensates are not only suitable for the production of press powders, but can also be used with advantage for the production of casting resins and adhesives and also for production be used for surface coatings and laminates. For these last four forms of application the mixtures can also be used without preconditioning be used.

The invention is illustrated in more detail by the examples below.

example 1

From various proportions of a mixture of 100 parts by weight of epoxy resin and 70 parts by weight Novolak resins were molded by heating, at 2%, calculated on the weight of the Epoxy resin, an organic metal compound, was used as a catalyst.

The moldings obtained using the aforementioned components were finely ground and the percent by weight of low molecular weight substance determined with boiling methyl ethyl ketone during 1 hour from a certain amount of the finely ground product could be extracted. the further conditions under which the moldings were produced, as well as the results of the extraction are compiled in the table below.

The table below shows that the higher the hardening temperature, the faster a complete hardening is achieved is chosen.

The epoxy resin used had an average of 1.85 epoxy groups per molecule and had a molecular weight of about 370 and contained 0.5 epoxy equivalent per 100 g. This resin was well known Way obtained by reacting 2,2-bis- (4-oxyphenyl) -propane with an excess of epichlorohydrin in the presence of alkali.

The novolak resin used was made by mixing 1 mole of phenol with 0.88 mole of formaldehyde (37%) and 0.1 g of 37% hydrochloric acid. Of the

Type of catalyst

Weight percent extractable low molecular weight product

Curing temperature ^{140 ° C}

Curing time 3 hours, curing temperature 180 ° C
Curing time 3 hours I curing time 6 hours

Cd stearate

Pb stearate

Al stearate

Sn oleate

Co-oleate

Sn resinate

Mn-naphthenate.,
Al-isopropylate ..,
Without a catalyst

34.1
16.4

39.0
2.5

20.6

24.1
4.3

48.9

8.1
3.5
3.8
7.6
1.7
5.9
5.5

11.9

4.4
2.2

6.0

1.5
5.7
2.4

6.1

35

40

The melting point of the novolak resin was 110 ° C, the molecular weight was about 800. The novolak resin was an average of about 7.7 phenolic hydroxyl groups per molecule.

Example 2

100 g of the epoxy resin described in Example 1 were mixed with 70 g of that described in Example 1 at 180.degree Novolak resin mixed. After cooling to 140 ° C., 2 g of cobalt oleate were added to this mixture added. The obtained mixture was made into a molded article by heating at 140 ° C. for 24 hours hardened. The hardened body had the following properties:

Heat distortion temperature according to ASTM ρ 648, 264 Psi .... 130 ° C

Izod impact strength 5.6 kg cm / cm

Rockwell hardness (E scale) 75

When extracting the finely ground solids with boiling methyl ethyl ketone for 1 hour it was found that 1% by weight of the low molecular weight substance could be extracted.

Example 3

In the manner described in Example 2, hardened bodies were produced using 100 g of the epoxy resin described in Example 1, 200 g of the novolak resin described below and 2 g cobalt oleate.

The hardened bodies had the following properties:

Heat distortion temperature per ASTM D 648, 264 psi 103 ° C

Izod impact strength 2.6 kg cm / cm

Rockwell hardness (E scale) 83

When extracting the finely ground solids with boiling methyl ethyl ketone for 1 hour it was found that 9% by weight of a low molecular substance could be extracted.

The novolak resin used was produced in the same way as the novolak resin described in Example 1, but with the exception that 1 mol of phenol with 0.9 mol of formaldehyde (as a 37% aqueous solution) was mixed. The novolak resin had a melting point of 127 ° C, a molecular weight of 900 and an average of about 8.8 phenolic hydroxyl groups per molecule.

65

Example 4

On a roller mill, the rollers of which were at a temperature of 80 to 100 ° C., 100 g of the mixture were deposited from epoxy resin and novolak resin, as described in Example 1, 100 g of wood flour and 2 g of cobalt oleate intimately mixed. Mixing was continued until the mixture became a rubbery mass had solidified. After cooling, the product formed was ground to a powder.

From this molding powder were at a temperature of 165 ° C, a pressure of 100 atm and a Pressing time of 6 minutes pressed bodies produced.

The compacts had the following properties:

Rockwell hardness (E scale) .... 76
Heat distortion temperature

according to ASTM D 648, 264 psi 110 ° C

Flexural strength 850 kg / cm ²

Izod impact strength 1.21 kg cm / cm

If the compacts produced in the manner described above then a further 6 hours When heated to 140 ° C, these properties could be improved as follows.

Rockwell hardness (E scale) 79

Heat distortion temperature .. 139 ° C

Flexural strength 915 kg / cm ²

Impact strength 1.39 kg cm / cm

Claims (3)

Patent claims: 1. Thermosetting molding, coating and adhesive based on epoxy resin made from epoxy resins, phenol aldehyde resins and organic metal compounds containing an epoxy resin with an average more than 1 epoxy group in the molecule and at least 0.1 epoxy equivalents per 100 g Resin, one made from an alkylated or non-alkylated monohydric or polyhydric phenol Novolak resin with an average of at least two phenolic hydroxyl groups per Molecule or a precondensation product of the epoxy resin and novolak resin, and the salt a polyvalent metal and a higher molecular weight optionally unsaturated fatty acid, Uric acid or a ketoenol tautomeric compound or the alcoholate of a polyvalent one Metal .. 2. Thermosetting composition according to claim 1, containing to 100 parts by weight of the epoxy resin 20 to 300 parts by weight of the novolak. 3. Thermosetting composition according to claim 1 and 2, containing the compounds of the polyvalent Metal in an amount of 1 to 8 percent by weight based on epoxy resin. Considered publications:
U.S. Patent No. 2,521,911. © 909 510/495 5.59