DE849754C - Fast curing resinous aminoplast compounds - Google Patents

Description

The invention relates to rapidly hardening, resinous aminoplast compositions, in particular for molding purposes, those of a urea formaldehyde and / or a melamine formaldehyde resin in combination with a latent hardening accelerator or catalyst and preferably an inhibitor such as hexamethylenetetramine, exist. The use of latent hardening accelerators or catalysts is known are fairly stable at temperatures below the normal hardening temperatures of synthetic resins, but accelerate hardening at the latter temperatures. So far, the following have been used as such: Phthalic acid, hexahydrophthalic acid salts, halogenated aliphatic monocarboxylic acids and arylated phthalic acids. Also, the use of inhibitors to prevent premature curing is more thermosetting Resins known; hexamethylenetetramine has already been used for this purpose.

According to the invention, tetrachlorophthalic acid or its anhydride is used as a latent catalyst in one Amount of about 0.05 to about 0.5% based on resin weight is used. This connection proved are highly effective at higher hardening temperatures, but rather ineffective at normal temperatures. The mass obtained contains an inhibitor, e.g. B. Hexamethylenetetramine has excellent Storage properties, hardens rapidly when heat is applied and provides hard moldings.

With otherwise approximately the same properties, the mass according to the invention enables a shortening the time required for molding and casting by a fifth to a third of the time otherwise required Duration. This shortening depends inter alia. on the type and shape of the article to be manufactured, those used Devices, etc. from. From the standpoint of the greatest performance and the best supervision processing it has been shown that masses of the type described, between about 0.25% and about 0.45% tetrachlorophthalic anhydride, calculated on the resin weight, are the best.

The tetrachlorophthalic anhydride can be in the form of finely divided solid particles or for the purpose of obtaining

a more extensive dispersion can be used as a mixture with other substances, these substances latent catalysts such as paratoluene, sulfonamide, or mere mold lubricants such as zinc stearate can. One can also use a small amount of the resin as a dispersant for the catalyst alone or use in conjunction with other materials listed above.

Example ι

A base having catalyst was ₀ filled by milling of a mixture of 50 parts of 35 ° / alpha cellulose, dry urea formaldehyde resin, 75 parts Paratoluolsulfonamid, 145 parts of tetrachlorophthalic anhydride and 0.2 parts of zinc stearate produced in a ball mill. The lump-free, smooth and uniform powder thus obtained was then used in various proportions as a catalyst for molding and casting compounds, as can be seen from the table below, in each case to 3000 parts of a dry urine-maldehyde resin filled to 35% with alpha cellulose added:

Table A.
25th

reason
mass with Hexa
methylene
tetramine zinc Tem pressure Time Kataly stearate temperature sator Parts Se Parts 8th Parts ⁰ C kg / cm ² Customers 12th 8th 12th 168 144 6th 14th 8th 12th 163 216 15th 13th 8th 12th 150 216 50 15th 8th 12th 163 144 7th 16 7th 12th 143 290 48 5 7th 12th 157 252 90 9 8th 6th 150 216 50 21 12th 143 144 6th

The objects produced, buttons, watch cases, radio boxes, etc., showed excellent appearance and same durability, which indicates complete and correct hardening.

Example 2

Additional catalyst-containing bases were prepared by grinding in a ball mill for about 24 hours made of:

Table B.

Urea-
shape
aldehyde resin
Parts Mole
relationship Paratoluene
sulfonamide
Parts Tetrachloride
phthalic
acid-
anhydride
Parts zinc
stearate 463
925
573 i: i, 7
i: i, 5 694
1387
859 1342
2683
1662 2
4th
2.5

The above bases were used in amounts ranging between 4.5 and 15 parts per 3000 parts Urea formaldehyde resin with 7 to 8 parts of hexamethylenetetramine and 12 parts of zinc stearate according to were as shown in Table A above in order to provide comparable results.

The following examples demonstrate the utility of tetrachlorophthalic anhydride alone, without use of dispersing or other materials such as lubricants and other catalysts.

Example 3

Molding compositions using finely divided tetrachlorophthalic anhydride alone have been prepared and deformed under the temperatures, pressures and times given in the following table :

Table C.

urea Tetra Hexamethylene
tetramine Zinc stearate
Parts temperature pressure Time formaldehyde resin
filled with 35%
Alpha cellulose chlorophthalic acid ■
anhydride Parts ⁰ C kg cm ² Seconds Parts Parts 7th 12th 168 290 120 3OOO 1.5 8th 12th 163 144 6th 3000 8th 7th 12th 157 252 90 3OOO 2 7th 12th 163 144 18th 3000 7th 8th 12th 163 144 8th 3000 9 8th 12th 165 144 6th 3000 10.5 8th beginning 6 143 216 25th 3000 9 later 3 8th beginning 6 163 144 8th 3000 8th later 6 8th beginning 6 168 144 6th 3OOO 10.5 later 6 8th beginning 6 163 144 7th 3000 9 later 6

Claims (1)

These masses were also used for buttons, watch cases, Radio boxes, etc. deformed. Colored moldings were made by incorporation a small amount of pigment is made into the mass at some stage of the process prior to deformation. Example 4 A urea formaldehyde resin with a filling of 35 ° / o alpha cellulose, calculated on the weight of the resin and of the filler therein, was 0.45 ° / ₀ Base and catalyst according to Example 1, o, 26 ° / ₀ hexamethylenetetramine, 0.5 % zinc stearate and _{/ 0} of a commercial iron-free, mixed 0.1 ° pink pigment. This percentage is based on the weight of the filled resin. These materials were ground in a ball mill to obtain a uniform dispersion, whereupon this dispersion was ^{molded at 163 ° and 144 kg / cm 2} pressure for 6 seconds to produce a pink-colored article. The above example was repeated by varying the percentage of the base composition, including catalyst, to 0.55 and o, y ° / ₀ and that of the pigments, and similar results were obtained. Although the invention is described herein only in relation to the deformation of urea-formaldehyde resin it is not limited to that. Any urea formaldehyde resin, whether z. B. filled with alpha cellulose, wood flour, asbestos, glass fibers, threads, fabric or not, which is useful as a molding material, can be used in practicing the invention. Those resins which have a molar ratio of 1.1 to 2.5 moles of formaldehyde per mole of urea are particularly suitable and expedient for the application of the invention for molding compositions. All acid curable Urea-formaldehyde resins or compositions containing such are also for the invention useful. In addition to the urea-formaldehyde resins, the melamine-formaldehyde resins can also be used effectively. So that a completely stable mass remains when the tetrachlorophthalic anhydride or the Acid itself, alone or in combination with dispersants or other acidic catalysts, in the the thermosetting aminoplast resin in question is dispersed and mixed, it is essential that a Inhibitor or retarder, such as hexamethylenetetramine, is also used to ensure the stability of the mass preserved. All of the examples described above include a lubricant such as zinc stearate. This particular one Calcium stearate and the like can also be substituted for lubricant. Patent λ ν s ρ r υ c ii: Rapidly hardening resinous aminoplast material, especially for molding purposes, made of urea-formaldehyde and / or melamine formaldehyde resin with a latent hardening accelerator or catalyst and preferably also an inhibitor, such as hexamethylenetetramine, characterized in that it is used as a latent catalyst Tetrachlorophthalic acid or the anhydride thereof in an amount from about 0.05 to about 0.5 ", calculated on the weight of the resin. 5359 9.