DE2337547A1 - EPOXY COMPOUND - Google Patents

Description

M 3279

PATENT AGENCIES £ »3 O / v> H /

Dr. - Ing.HANS RUSCHKE Dipl.-In ^. OLAF RUSCHKE Dipl.-Ing. HANS E. KUSCHKE

1 BERLIN 33 ^

Auguste-Viktoria-Strasse 65,;

Minnesota Mining and Manufacturing Company, Saint Paul, Minnesota 55101, V.St.v.A.

Epoxy compound

The invention relates to a composition based on epoxy resin and a Method of applying the same. The invention has particular, but not exclusive, reference to a mass known as Coating for metals, in particular as a soldering body in automobile construction, is suitable, as well as a method for applying such Solder body mass. The invention will be described with primary emphasis on the solder body aspects.

To this day, automobile original equipment manufacturers use lead solder in the construction of automobile parts. Solder lead is applied to areas such as the joints of metal plates to provide a smooth, uninterrupted surface to obtain. Solder lead has many attractive properties such as low cost, quick application, good strength and immediate machinability such as sanding and paintability.

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Given these many advantages, a substitute for solder lead is not so easy to find, but the effort to achieve one To obtain an alternative, because of the many dangers and inconveniences, which lead generally imposed on the working people, users and the environment, revived. For the working man

* · There is exposure to poisonous lead fumes and dust inhalation.

% There is a cost and loss of time for the user as a result of medical tests to monitor the effects of such exposure. There is a risk of lead pollution of the air and water in the surrounding area, which occasionally occurs when wagons ready for scrap are destroyed.

Nonetheless, until now, a suitable solder body with reduced Danger to health and the environment, which, however, has the necessary properties of a soldering body, in particular does not yet show fast curing time, sandability, paint absorbency, and fatigue and impact resistance found. Solder lead has been replaced to some extent in the less quality-conscious automotive aftermarket, however, the replacements are often more time-consuming to process than lead solder and do not provide the good results of lead solder.

The primary aim of this invention is to propose a material which is able to meet the requirements for a solder body, including an application means that should be relatively fast and safe.

These and other objects are achieved according to one aspect of the invention by a small-valued mass which is a homogeneous mixture the end

(a) thermosetting, free-flowing, stable at room temperature, containing small-scale material

(1) a solid, thermosetting resin;

(2) at least one compound which is reactive with this resin and which is present in a sufficient quantity

is to cure this resin, this compound being . . has at least 2 active hydrogen atoms and

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Temperatures at or below) the softening point this resin is stable and with this resin at a temperature above the softening point of this resin reacts to form a tough, infusible, insoluble polymer; and

(b) a solid, inert component with a density greater than 1 g / cm2 in sufficient quantity to provide a practically void-free coating of this mass when this resin cures with a density of at least 1 g / cm2,
"having.

The inert component may be particulate in the thermosetting Material preferably homogeneously incorporated filler or be a powder metal that is separate from this small-scale material, but mixed with it. The preferred one Resin for use in practicing the invention is a solid epoxy resin.

According to another aspect, the invention proposes a smooth, Coating practically free of voids on a suitable carrier made of a mass which contains the reaction product from (l) and (2) - see above - in a fused solid mass, with this inert metal component within it Mass is distributed. The preferred carrier is an automobile part panel joint. The invention closes also a method for applying the mass according to the invention, which consists in that one

(1) a gas suspension of this small-sized mass in the dry Condition forms;

(2) a contact between a suitable carrier and this gas suspension from this small-scale mass on a creates a suitable carrier, whereby this mass is drawn on the carrier;

(3) this mass to a temperature above the softening point the resin component of the same as well as sufficient Temperature in order to react with this resin

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to activate capable compound, whereby this resin arrives in the hardened state on this carrier; and

contacting and heating continues to produce a fused mass at least about J5 * 175 mm thick this' composition to form in which is this resin is in the hardened state and this inert component is distributed within this mass.

The gas suspension is preferably submitted by air atomization, i.e. the small-scale mass is in a moving Suspended stream of air from a suitable source.

The epoxy resins useful in practicing this invention are thermoset, i.e., thermosetting, solid Polyethers with an average of more than one 1,2-epoxy group per molecule, including diglycidyl ethers of polyhydric phenols, glycidyl ethers of novolak resins, glycidyl ethers of aliphatic Glycidyl ethers containing polyols and nitrogen. Preferred diglycidyl ethers of polyhydric phenols comprise the condensation product of epichlorohydrin and bisphenol A, especially those having an epoxy equivalent between about 550 and about 700 and a softening point between about 75 ° C and 90 ° C. Typical, Epoxy novolak resins suitable here have an epoxy equivalent between 190 and 285 and a softening point of 70 ° - 99 ° C. Examples of commercially available bisphenol A- type epoxy resins are sold under the trademarks Epon 1002 (a solid diglycidyl ether des bisphenol A, epoxy equivalent weight 600 - 700) and DER 662 (a solid diglycidyl ether bisphenol Α resin, epoxy equivalent weight 575 - 700). The glycidyl ethers of Novolak resins are characterized by phenyl groups which are linked by methylene bridges to the phenyl groups sedentary epoxy groups; Commercially available resins are sold under the trade name Epi Rez 521 (a polyglycidyl ether of phenolic -Formaldehyde novolak, epoxy equivalent weight 190 - 210) and Epotuf 57-171 {a polyglycidyl ether of o-cresol-formaldehyde- -Novolak, epoxy equivalent weight 275 - 285). An im

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Commercially available 'cycloaliphatic epoxy resin is the one below Resin sold under the trade name ERRA 4205 (epoxy equivalent weighted 91-102, melting point 45 ° C).

The curing agents useful in practicing this invention must be above the softening point of the epoxy resin component be reactive in order to be mixed homogeneously with it in the production of the composition according to the invention, without initiating the hardening reaction. In general, the activation temperature should be of the curing agent are at least 5.55 ° C. (10 ° P) above the softening point of the epoxy resin. Suitable hardeners are those described in US Pat. No. 2,847,395 the formula

-atf * · - · "a ™ '

3-n

where R is a polyvalent organic radical with ν valences, η is a number from the group: zero and integer 1, each Z is a member of the group; Amino, hydroxyl and carboxylacylhydrazide radical, and a is equal to v-1. A preferred group of compounds includes those having at least two NEig'Reske * ¹ * of which at least one is part of a carboxylacylhydrazide residue. The dihydrazides are particularly valuable. Other conventional epoxy curing agents can be used alone or in combination so long as they are stable at or below the softening point of the selected epoxy resin. Examples of hardening agents other than those given above are dicyandiamide, chlorenedio anhydride and various other known hardening agents such as substituted mono- and polyureas.

Catalysts or accelerators, well known to those skilled in the chemistry of epoxy resins, are used to further increase the rate of reaction between the hardener or curing agent and epoxy resin. General .tertiäre amines and their acid ^ salts are effective in the curing

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to increase the speed of the preferred compositions at elevated temperatures and yet not unduly affect the stability of the composition when it is held at room temperature or below. Examples of catalysts are QCrMe.thylbenzyldimethylamine, acid salts of tris (dimethylaminomethyl) phenol; Diethylaminopropylphthalimide, as well as the salicylic acid salt thereof, and 2, K, 6-Tridimethylaminomethylphenol.

In addition to epoxy resin, hardeners and catalyst (the latter optionally, but preferably) the composition contains an inert component in an amount which is essential for use as a solder body turned out to get a suitable coating. This inert component can be a filler such as that used by technology or a powder metal, or preferably a combination of the two. Suitable fillers include mica, Asbestos fine material, alkylammonium bentonite, iron oxides, tallow, clay, flint, diatomaceous earth, Venetian shot and the like.

The powder metal used in the bulk of this invention can Be aluminum, iron or copper. Aluminum is particularly desirable because it provides a coating that is economical, practical Free of cavities, quick to sand, can be used on sharp edges (i. Orig. featherable) and for paints is receptive. The powder metal component of the invention Mass should provide excellent heat distribution to the mass ensure that the mass can be heated evenly to the temperature at which the hardening reaction occurs and localized elevated temperatures, which can interfere, are avoided.

Whether filler or metal powder having the inert component alone or in combination, has a density greater than 1 g / cnr ^5, and in a sufficient amount present Ain to form a coating of the cured composition to provide this invention having a density greater than 1 g / cnr. In general, this requires that the composition according to the invention, which contains the epoxy resin and hardener, has at least about 50% by weight of the inert component

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contains, although very dense inert components are less required- ' borrowed can make to meet the condition that the amount of inert components is dimensioned in such a way that the density of the mass is adjusted to at least 1 g / cnr.

In addition to the inert component, the mass can contain components and it preferably contains them, which have potting ability and the leveling ability of the mass in the softened or molten state and the sprayability of the heat-curable component the bulk of this invention promotes. Flow control agents for epoxy resins are well known in the art, a preferred one Agent is a complex polymeric material sold under the trade name Modaflow.

The amount of the various constituents present in the composition according to the invention can vary within relatively wide ranges. The hardening or hardening agent can be present to such an extent that the epoxy resin can be cured to an infusible, insoluble state. About 0.75 to 1.5 equivalents of such a curing agent per epoxy equivalent can be used. An effective amount of the catalyst, when present, should be incorporated into the thermosettable, particulate material containing the epoxy resin and hardener, with an amount being preferred which provides at least about 0.15 or more amino hydrogen equivalents per epoxy equivalent. The total amount of inert component to be incorporated into the bulk has been discussed above. Preferably, the inert component to an extent of about 50% to 90 wt -.% Present, and even more preferably of at least 50 to 70 wt .- ^. When both filler and metal are present, the amount of each can vary from greater than zero to less than 100 percent. Preferably, the metal is up to the amount of 20-80 wt .- ^, and more preferably 20-60 wt -.% Present. When a filler is used, the homogeneous mixing of this component generally requires mixing the filler with softened or molten epoxy resin prior to the formation of the particulate material. The powder metal is

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mixing the metal with the formed, heat-hardenable small-sized material mixed homogeneously.

The composition of the present invention is prepared by careful Mixing the epoxy resin, hardener, catalyst and filler, in order to incorporate these components, preferably homogeneously in a mass; which is subsequently crushed to make atomizable To obtain particle sizes. The epoxy resin is generally heated to a softened state and the other ingredients incorporated therein with the resin serving as a matrix. The particle size of the material containing the small part Epoxy resin should be such that it can be suspended in a gas to form a cloud, such as that Case when atomization or fluidized bed methods are used reach. A small size of 100 mesh (0.147mm) or less is desirable. The gas can be air or some other inert gas medium. The powder metal generally becomes dry mixed homogeneously with the epoxy resin containing the small-sized material as a uniform mixture of separate particles « The size of the powder metal similarly provides a suitable one Great for use by spray or fluidized bed methods and is generally 0.147 mm or less.

'The particulate matter of this invention can be used as a solder body or Filler for metal joints or as a coating or sizing over various substrates, especially metal or Plastic materials such as fiberglass can be used. As a • soldering body in mobile parts, the compound is applied quickly, cures quickly (generally in less than 60 seconds at 2o4.4 ° C), is free of voids, easy to sand and opposite Resistant to shock and the effects of severe environmental conditions. There is no tedious surface preparation of the carrier required, although removal of surface contaminants such as rust, grease and oil is desirable.

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The mass can be applied by a variety of methods including electrostatic atomization, fluidized bed, fluid coating, and conventional atomization. A gas suspension is preferably formed from the homogeneous mixture of small particles, generally as a cloud from a spray gun or a fluidized bed, small particles. The mass is preferably subjected to curing temperatures of the epoxy resin / hardener combination shortly before or after the small-particle material comes into contact with the carrier to be coated. The temperature used is to initiate at least that temperature necessary to activate the heat aktivi _d @ n @ rbar hardener for the curing reaction within the desired time, generally less than two KLnuten and preferably less than one minute. The temperature-time exposure should not exceed the point at which any component of the mass or the carrier is adversely affected in such a way that it can no longer function satisfactorily. A particularly desirable method of applying the particulate mass of this invention includes forming a spray stream of the particulate matter described herein, passing that spray stream through a thermal zone for a time and at a temperature which. sufficient to soften and initiate the hardening of the epoxy resin, as well as the mounting of the thus treated mass on a metal support, the process being continued until a coating of at least about 5.175 mm thickness has been formed. Preferably, the metal support has been preheated prior to peeling at least to the softening temperature of the epoxy resin and generally to the higher curing temperature. The mass located on the carrier forms a molten mass which, upon hardening, solidifies into a fused, solid mass.

The following examples are provided for illustrative purposes; all parts and percentages relate to weight if nothing other is indicated.

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Example I.

M 3279

SD-636 Epoxy Resin (bisphenol A / epichlorohydrin, epoxy equivalent weight 550-675) Modaflow (trade name for a polymeric flow control agent)

4 X Mica (silicate made from Al and Mg)
Aluminum powder ($ 99 325 mesh or less) 2,4,6-tridimethylaminomethylphenol
Curing agent (80.5 wt -.% Isophthalyldihydrazid, 19.5 wt .- # dicyandiamide)

Parts by weight

43.72

0.35 32.15 19.90 0.35

3.53

The above components, with the exception of the aluminum powder, are initially heated on a two roll rubber mill by binding the epoxy resin and then by adding the other components mixed homogeneously. After mixing, the material becomes peeled off and allowed to cool. After cooling, the material is ground to a particle size of 3.175 mm or smaller. The aluminum powder is then added to the ground mixture and mixed in homogeneously on a roller mill until dry a uniform mass is obtained.

A vertical steel panel is made using a propane torch heated to 204.4 ° C. The flame of the torch is then rotated parallel to the face of the board and the powder out of one Powder suction syringe sprayed through the flame and onto the surface of the board. The strength of the powder flow is adjusted so that it either reaches the board surface in the molten state or melts immediately after contact. The coating speed is approximately 18 g / min. Towards the end of the application period, the board and the sprayed mass allowed to cool to room temperature. The mixture was found to harden, giving excellent adhesion to the steel has and can be quickly sanded to a smooth, from.

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To obtain a surface that is free of cavities and appears metallic.

Other steel panels are made in a similar manner and tested to determine the suitability of the product as a substitute for lead solder in the manufacture of automobiles. It will found that the mass has the following test properties: *

1. Shore D hardness: 78

2. Heat resistance: No cracking, blistering, charring or Loss of adhesion after 30 minutes of exposure at 176.7 ° C.

3. 28.9 ° C impact test: No breakage or loss of adhesion 10 beats at 28.9 ° C. ■

4. Thermal shock: No breaking or loss of adhesion has been observed Test cycles noted (panel held at 176.7 ° C for 20 min, then balanced in ice water).

5. Paint pick-up and pick-up for lightly colored spray paint: The paint applied to the sanded panels according to normal automotive practice showed no staining or disruptive phenomena after 96 hours of exposure to UV light

■ at 23.9 ° C or 250 hours of standard conditions in one Atlas Weather Meter (Type XW) (temperature and other conditions). ♦

6. Overlap Shear Strength: 2.54 cm wide, 1.27 cm lap shear panels were made using steel panels and the mixture as an adhesive. The tablets were tested according to ASTM-D-1002-64 and resulted in an average strength value of 200 kp / cm

7. Environmental Tests: As panels were made in 6. above exposed to different environments and then to overlap shear strength tested. The environments and test results

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were as follows:

a) 10 days at 87.8 ° C 198 kp / cm ²

b) 10 days in 5 $ salt spray 183 kp / cm

c) 10 days at 37.8 ° C and 100 % relative ₂

Humidity ■ 196 kp / era

d) 10 days "immersion in gasoline - 197 kgf / cm

Example II

The powder prepared as in Example I is applied to a vertical steel panel by spraying the powder onto the surface of the panel Applied from a modified fluidized bed coater while two 20 amp heat guns are aimed at the board. the Heat guns are arranged in such a way that a temperature of around 176.7-2152.2 ° C is maintained on the surface of the board. The powder is aimed at the board surface by the heated air flow from the guns. The powder instantly melts at or just about before the point of impact. The finished product is hardened, tight and gives a surface free of cavities after sanding. In this test, a horizontally swiveling steel panel is used from about 30 * 4-8 cm x 30> ^ 8 cm from an upright position swayed to strike a steel lock at the lower vertical position. The hardened material, which Applied in a horizontal composite over the board surface must not break or lose adhesion.

Example III

Powder from Example I is used to make the flanges of automobile wheels to be coated by the powder from an air-powdered Powder applicator applied to the rims of the rotating wheel immediately after the rim passes the flame of a stationary propane torch. It becomes even, hard, good Bound layer of hardened mass built up on the wheel rim.

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Example IV

Example I is repeated using an aluminum panel in place of the steel panel. Again, excellent adhesion obtained, and the cured product is hard, dense and, after sanding, is found to be free of voids.

Example V '

Epoxy resin from Example I __ ■ 43.72

Modaflow "0.35

2,4,6-tridimethylaminomethylphenol 0.35

Hardener from Example I 3.53

The above materials are mixed on a two-roll rubber mill and then pulverized as in Example I. This powder is then mixed with either kX mica or aluminum powder as follows:

Example (parts by weight)

V VI VII VIII IX X XI XII

example
powder V 100 95 90 70 50 30th 10 5 4X mica - 5 10 30th 50 70 90 95 * XIII XIV XV XVI XVII XVIII XIX example
powder V 95 90 70 50 30th 10 5 aluminum
powder 5 10 30th 50 70 90 95

These mixtures are made up by the flame of a propane torch the area of a steel sheet preheated to about 176.7-232.2 ° G sprayed on as in Example I. The results are as follows:

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example V About train speed g / sec. actually density g / cnr • No. VI cnr / sec. theore t. % d.Theo VII 0.10-0.14 0.63-0.72 rie VIII 0.16-0.19 0.02 0.60 1.20 52.5-60 IX 0.13 0.22 0.64 1.23 48.7 X 0.34 0.29 o, 6o 1.26 50.8 XI 0.48 0.39 1.21 1.44 41.7 XII 0.30 0.23 1.28 1.66 72.9 XIII 0.18 0.27 1.01 1.96 65.3 XIV • 0.27 0.25: 1.00 2.40 42.1 XV 0.25 0.15 0.78 2.54 39.3 XVI 0.19 0.20 0.61 1.24 • 62.9 XVII 0.32 0.25 0.69 1.27 48.0 XVIII 0.36 .0.33 0.88 1.45 47.5 0.38 0.27 1.18 1.68 52.3 0.23 0.21 1 * 60 2.00 59.0 0.13 2.47 64.7

From the above values it can be seen that compositions with either little or no filler have specific gravity values less than 1.0. A microscopic examination of these cured materials shows that they have a large number of voids. Those masses with very high filler contents turn out to be weak. ' Those samples with 50 to 70 % 4x mica content and those with 50 to 70 % aluminum powder content appear very dense and solid.

The. actual density determinations were made with the cured sample using ASTM C 97-47 (Absorption and Bulk Specific Gravity of Natural Building Stone) and the use of an Ohaus Cent-o-gram (trade name) triple jet balance. After curing, the sample was removed from the substrate for testing. In order to aid the removal, the substrate was coated with a release substance before the mass was applied.

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The composition of this invention can be exposed to temperatures. which are sufficient for the mass to reach a hardening temperature - (121.1-260 ° G, preferably 176.7-232.2 ° C) and within cures in 3 minutes and in many cases within 1 minute or less. In order to keep the curing temperatures in a possible To achieve quick time, the heat source can reach up to 538 C or even higher, e.g. when using propane torches or the like. It has been found to contain epoxy resins and hardeners Masses as they are described here, but which do not contain the inert solid component, especially the powder metal, cannot withstand the heating conditions necessary to produce a cure in the period of time during which the masses of the present invention. Time is of course an important factor in the assembly line manufacturing of automobiles.

The composition of this invention can be made in situ in a single step applied and cured, a skill that makes them extremely attractive for automotive assembly line manufacturing power. The heating of the 'mass to a hardening temperature and The mass can harden almost immediately or within a few seconds after the small mass hits the substrate, take place.

- patent claims -

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Claims (1)

- 16 - M 3279 Godfather nt a η s ρ r. before 1. Composition, which contains a thermosetting, free-flowing, fine-grained material which is stable at room temperature (1) a solid, thermosetting resin; (2) at least one compound reactive with this resin, which is present in an amount sufficient to to cure this resin, this compound having at least 2 active hydrogen atoms and at temperatures at or is stable below the softening point of this resin and with this resin at a temperature above the softening point of this resin reacts to form a tough, infusible, insoluble polymer; has, characterized in that it contains a solid, inert component with a density greater than 1 g / cm contains, this component being present in an amount sufficient to provide a virtually void-free coating to deliver this mass upon hardening of this resin, this mass having a density of at least 1 g / cm3. 2. Composition according to claim 1, characterized in that this resin is an epoxy resin. 3. Composition according to claim 1, characterized in that this inert component contains a filler and a powder metal. 309885/135 1 - 17 - 'M 3279 Mass according to claim 1, characterized in that min. at least one of these compounds that can react with this epoxy resin is a dihydrazide. 5. Composition according to claim 1, characterized in that this inert component contains aluminum powder. 6. Composition according to claim 2, characterized in that this epoxy resin is a bisphenol A / epichlorohydrin reaction product ■ wherein at least two of these epoxy resin-reactive compounds is isophthalyl dihydrazide and dicyandiamide and this inert component is a silicon dioxide - Contains filler and aluminum powder. 7. The method, characterized in that one (1) a gas suspension of the particulate matter according to claim 1 forms when dry, (2) creates a contact between a suitable carrier and this gas suspension from this small mass, whereby this mass is drawn up on this carrier, (3) this mass to a temperature above the softening point their resin component and heated to a temperature sufficient to be reactive with this resin To activate the compound, whereby this resin gets into the hardened state on this carrier, and (4) contacting and heating to form a fused, solid, practically void-free mass of this composition continues, in which this Resin is in the cured state and this inert component is distributed within this mass. 8. The method according to claim T, characterized in that this gas suspension is given by air atomization of this mass. Ro ./Br. 309885 / 13S1