DE1569511A1 - Abrasives - Google Patents

Description

The present research examines soles and abrasives made from them. It refers to "insbe®ood © r © on SehleifTsiitt ©! Suit improved flexural strength uftä". Maturity "b @ i ^ giniäe teiaperatur .and when he elevated temperatures = ₀ - - -

- Abrasives υ ^ 'ijie Soleif solleifa © a _s: Sohl @ if räder etc. _O9 ' hab @ a suitable. A -good flexural strength wad toughness at room temperature © Eig. for example ^ eis © @ia Aus @ iiianderbF © ühaB due to. der-Centrifugal forces '& v ^ \ r®rm® idea ₀ A sur improvement of the toughness «oi flexural strength ψ®η Schl @ .ifsaitt @ ln- suggested it? © rfahr @ .a consisted in the BiErir © rl @ ili« ag th © rtBOp'lsietischer Mat © - rialien ₉ 'like S ₀ B ₀ Pol |' viöflae © ta3.e unä. anders® Viay

. sate) ο Bsi # © 3? Tay ^ esiaag w @ M © i3 di @ Seiileiffflittel jeäoeh

the abrasives at their normal use temperatures an unacceptably low level. Low limits on use temperatures make grinding speeds slow necessary and are otherwise undesirable. '

The aim of the present invention is therefore to provide abrasive materials and abrasives with improved Flexural strength and toughness at room and elevated temperatures.

Another object of the present invention is to provide a method of improving flexural strength and toughness of abrasives at cinnamon and elevated temperatures.

These and other goals are achieved with abrasive preparations in accordance with the present invention obtained from abrasive grains, a thermosetting Resin binder and a thermoplastic polyhydroxy ether in an amount of up to 60 parts by weight per 100 parts by weight of the heat-resistant Resin binder exist.

Surprisingly, it has been found that the incorporation of the thermoplastic polyhydroxyether in abrasive preparations one Improvement in flexural strength and toughness by about 50% at room temperatures instead of the usual 10-20% improvement achieved with thersaoplastiachen additives.

However, it was completely unpredictable that this thermoplastic Additives actually reduce flexural strength and toughness increased about $ 50 at 260 ° and more, and not like others thermoplastic additives do this, which degrade use properties at high temperatures.

This merkliohs improvement in flexural strength is quantitative is illustrated in the following table in which identical abrasives are compared, where "A" using a Usually used heat-resistant, non-modified

009824/183 5 BAD original

Phenol adhesive and '"B" using a device according to the invention; Naoli Example 1 produced resin blinder became ..- "■" "■ -, - \ -

Table 1 A. - - B- actual percentage Test- . Flexural strength kg / cm "" 248,
-112,
■ 87 9 5
0
5 ' 388.5--
163.8
136.5- improvement
about A from B to temp ,; ⁰ C. +56
+46
+56 " 25 "
260
29O '

The bezel earring used here "thermoplastic ■ polyhydroxy» äther "sioto. refers to practically linear polymers of the general" = my Formeis' _. . .

in which D stands for the remainder of a dihydric phenol | S is a hydroxyl group-containing radical of an epoxy-s uod;.; . Stands for the degree of polymerisation and has a value iron raioc at least 30 and preferably 80 or more. The term "thermoplastic polyhydroxy ^{ethers H} should also include mixtures of at least two thermoplastic polyhydroxy ethers",

The dihydric phenol which supplies the phenol radical 'B can either a -bivalent, mononuclear © - phenol, such as hydroquinone and Resor = an ,, or a zw & valued. polynuclear phenol, such as materials of the following general formula,

HO

kr

in what-ar for. an aromatic, divalent hydrocarbon such as -laphthylon and
the same qü®t

s-tehtj

^: · Ηέ

BAD ORtQINAL

0Ö9824 / 183

preferably with 1-4 carbon atoms, halogen atoms, ie fluorine, chlorine, bromine and iodine, or alkoxy radicals, preferably with 1-4 carbon atoms; r and ζ are integers with a value from 0 to a maximum of the value corresponding to the number of hydrogen atoms on the aromatic radical (Ar) that can be replaced by substituents; and R ¹ is a bond between adjacent carbon atoms, as in dihydrodiphenyl, or a divalent radical, such as -C-, -0-, -S-, -SO-, -SO ₀ - and -SS-,

Il ~ C. '*

as well as Q

divalent hydrocarbon radicals, such as alkylene, alkylidene, cycloaliphatic radicals, for example cycloalkylene and cycloalkylidene, halogenated, alkoxy- or aryloxy-substituted alkylene, alkylidene and cycloaliphatic radicals, and alkarylene and aromatic radicals including halogenated, alkyl, alkoxy or aryloxy-substituted radicals ring fused to an Ar group; R ¹ can also stand for polyalkoxy or polysiloxy or for two or more alkylidene radicals which are separated by an aromatic ring, a tertiary amino group, an ether bond, a carbonyl group or a sulfur-containing group, such as a sulfoxide group, etc.

Examples of particular dihydric polynuclear phenols include: The pis (hydroxyphenyl) alkanes, such as 2,2-bis (4-hydrophenyl) propane, 2,4'-dihydrodiphenylmethane, bis- (2-hydrophenyl) -methane, bis- (4-hydrophenyl) -methane, Bis (4-hydroxy-2,6-dimethyl-3-ynethoxyphenyl) methane, l, l-bis (4-hydrophenyl) -ethane, l, 2-bis- (4-hydrophenyl) -ethane, l, l-bis- (4-hydroxy-2-chlorophenyl) -ethane, 1,1-bis- (3-methyl-4-hydrophenyl) -ethane, 1,3-bis- (3-methy1-4-hydroxyphe ~ nyl) propane, 2,2-bis (3-phenyl-4-hydroxyphenyl) propane, 2,2-bis (3-isopropyl - ^ - hydroxyphenyl) propane, 2,2-bis- (2-isopropyl-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxynaphthyl) propane, 2,2-bis (4-hydroxyphenyl) pentane, 3,3-bis (4-hydroxyphenyl) pentane, 2,2-bis- (4-hydroxyphenyl) -heptane, bis- (4-hydroxyphenyl) -phenylmethane, Bis- (4-hydroxyphenyl) -cyclohexylmethane, 1,2-bis - ^ - hydroxyphenyl) - !, 2-bis (phenyl) propane, 2,2-bis (4-hydroxyphenyl) -

1-phenylpropane, etc.

009824/1835

: Di (hydroxyphenyl) sulfones, such as bis (4-hydroxyphenyl) sulfone; 2,4'-dihydrodiphenylsulfone, 5 ^f -chloro-2,4'-dihydrodiphenylsulfone,: 5'-chlorine ^^ '- dihydroxydiphenylsulfone, etc .;

; Di (hydroxyphenyl) ethers, such as bis (4-hydroxyphenyl) ethers, the 4,3'-, 4,2'-, 2,2'-, Z ^ '- dihydroxydiphenyl ethers, 4,4'- Dihydroxy-2,6-dimethyldiphenyl ether, bis (4-hydroxy-3-isobutylphenyl) ether, bis (4-hydroxy-3-isopropylphenyl) ether, bis (.- 4-hydroxy-3-chlorophenyl) - ether, bis- (4-hydroxy-3-fluorophenyl) -ether, bis- (4-hydroxy-3-t) romphenyl) -ether, bis- (4-hydroxynaphthyl) -ether, bis- (4-hydroxy-3 chloronaphthyl ether, bis (2-hydroxydiphenyl) ether, 4,4'-dihydroxy-2,6-dimethoxydiphenyl ^{ether, 4,4 l} -dihydroxy-2,5-diethoxydiphenyl ether, etc .;

Also suitable are the bisphenol reaction products of 4-vinylcyclohexene and phenols, such as 1,3-bis (p-hydroxyphenyl) -1-ethylcyclohexane, and the bisphenol reaction products of dipentene or its isomers and phenols, such as 1,2-bis- (p-hydroxyphenyl) -1-methyl-4-isopropylcyclohexane, and bisphenols such as 1,3,3-trimethyl-1- (4-hydroxyphenyl) ^ 6-hydroxyindane and 2,4-bis- (4- hydroxyphenyl ) -4-methylpentane, etc.

Particularly suitable dihydric polynuclear phenols have the

Formula / " _λ . , _γ , ..

■ 'ζ

- R « J / ^ S-OH

in which Y and Y 'have the meaning given above;, r and ζ have a value from 0 to 4, and R ¹ is a divalent saturated aliphatic hydrocarbon radical, in particular an alkylene or alkylidene radical with 1-3 carbon atoms, and a cycloalkylene radical with up to to 10 carbon atoms.

Mixtures of dihydric phenols can also be used, and where the designation »bivalent Phenol "or" dihydric polynuclear phenol "used mixtures of these compounds with

000824 / $ 183

be included.

The epoxide which supplies the radical E containing hydroxyl groups can be a monoepoxide or mepoxide. "Epoxide ¹¹ is understood to mean a compound containing an oxirane group, ie an oxygen atom attached to two vicinal aliphatic carbons

is bonded to atoms, such as. - C - C -. A monoepoxide

contains such an oxirane group and provides a radical E with a single hydroxyl group; a diepoxide contains two such oxirane groups and yields a radical E with two hydroxyl groups. Saturated epoxides, ie diepoxides, which are free of ethylenically unsaturated bonds, ie]> C = C ^, and acetylenically unsaturated bonds, ie, -C = C-, are preferred. Halogen-substituted saturated monoepoxides, ie the epihalohydrins, and saturated diepoxides which contain only carbon, hydrogen and oxygen are particularly preferred, especially those in which the vicinal or adjacent carbon atoms form part of an aliphatic hydrocarbon chain Oxirane oxygen, ether oxygen -0-, oxacarbonyl oxygen
0 0

Il Il

-C-O-, carbonyl oxygen -C-, etc. be.

Special monoepoxides are e.g. epichlorohydrins, such as epichlorohydrin, Epibromohydrin, 1,2-epoxy-1-methyl-3-chloropropane, 1 ^ -Epoxy-i-butyl ^ -chloropropane, 1,2-epoxy-2-methyl-3-fluoropropane etc.

Suitable diepoxides are e.g. diethylene glycol bis (3,4-epoxycyclohexane carboxylate), Bis (3,4-epoxycyclohexylmethyl) adipate, Bis (3,4-epoxycyclohexylmethyl) phthalate, 6-methyl-3 »4-epoxyoyolohexylmethyl-6-ynethyl-3,4-epoxycyclohexanecarboxylate, 2-chloro-3,4-epoxyoyolohexylmethyl-2-chloro-3,4-epoxycyolohexane. oarboxylate, diglyoidyl ether, bee (3,4-epoxycyclopentyl) ether,

00982W1835

BATH ORIGINAL

1,5-pentanediol bis (6-methyl-3,4-epoxycyclohexylmethyl) ether, bis (2,3-epoxy-2- ethylhexyl) adipate, diglycidyl maleate, diglycidyl phthalate, 3-oxate1; racyclo- / 4 ".4.0.1 ^{7 '10} .O ^^ - undec-8-yl-2,3-epoxy propyl ether, bis (2,3-epoxycyclopentyl) sulfone, bis (3,4-epoxyhexoxypropyl) sulfone, 2,2 • -sulfonyl diethyl diethyl bis- ^ j ^ -epoxycyclopentanecarboxylate), 3-oxytetracyclo- / t. 4.O.1 ⁷ ' ¹ ° .O ^{2 >> 4} __7-undec-8-yl-2,3-epoxybutyrate , 4-pentenal-di- (6-wethy 1-3., 4-epOxycyclohexylmethyl) -acetal, ethylene glycol bis (9,10-epoxystearate), diglycidyl carbonate, bis (2,3-epoxybutalphe, nyl) -2-ethylhexalphosphate , Diepoxydioxane, butadiene dioxide and 2-, 3-diethylbutadiene dioxide. Preferred M-epoxides are those in which the oxirane groups are bonded to an electron-donating substituent which is not bonded directly to the carbon atoms of this oxirane group.

Such diepoxies have the grouping

III

A - G - G - C

in which A stands for the electron donating substituent,

like -0-, -N-, -S-, -SO-, -SO ₀ -, j \ _n or -Ni έ —υ— u,

Q SO ₉ .

I ^ -

where Q is a saturated hydrocarbon radical, such as a Alkyl, cycloalkyl. » Aryl or aralkyl radical.

In the manufacture of thermoplastic polyhydroxy ethers a single monoepoxide or diepoxide or a mixture of at least two monoepoxies or diepoxies are used; and the terms "Monoepoxyd" and "Diepoxyd" should also be used Mixtures of at least two monoepoxies or diepoxides include.

009824/1835

■ r. ■ "-.;.

The thermoplastic polyhydroxyether used was prepared by reacting equimolar amounts of 2,2-bis (4-hydroxyphenyl) propane and epichlorohydrin along with sodium hydroxide. The device used was provided with a sealed stirrer, thermometer and reflux condenser. In these were given:

2,2-bis (4-hydroxyphenyl) propane 114.5 parts (0.5 mol)

Epichlorohydrin (purity 99.1 96) 46.8 parts (0.5MoI)

Ethanol 96.0 parts

Butanol 10.0 parts

Sodium hydroxide (purity 97.5-96) -22.6 parts Water 70.0 parts

The above mixture was stirred for 16 hours at room temperature to cause the initial coupling reaction; then one hour at 80 ⁰ C. was heated 60 cc of a 7: 3 mixture of toluene and butanol is added and the mixture a further 2 hours at 80 ⁰ C. heated. A further 50 parts of a 7: 3 mixture of toluene and butanol and 4.5 parts of phenol were then added and the contents of the vessel were heated to 80 ° C. (reflux) for about a further 2.5 hours. After cooling, the reaction mixture was admixed with 200 parts of a 7: 3 mixture of toluene and butanol, 100 parts of water were added and the contents were stirred while dissolving the salts present in the reaction mixture. The contents of the vessel were allowed to settle for 10 minutes, a lower salt phase forming which was decanted off. The upper phase containing the polymer solution was washed twice in succession with 160 parts of water containing 4.5% butanol each time. The washed .Polymerisatlösung was acidified by stirring with a mixture of 1 part of 85- ^ phosphoric acid with 100 parts of water (pH = 2) for one hour. The upper polymeric solution phase was again separated off by decanting and washed four times with 200 parts each of water containing 4.5% butanol. The washed polymer was then coagulated in 1000 parts of Ieopropanol, filtered and dried. For example, a thermoplastic polyhydroxy ether was made from 2,2-bis (4-hydroxyphenyl) propane and epi-

009824/1835

. '. ■ · - ■ ■' '■ _ ■ ■. - - 9 -. . ■ '. . obtained chlorohydrin with a melt flow of 7.0 dg / min.

Thermoplastic polyhydroxy ethers with a. * Melt flow between 0.5 and 20 or more, especially 2 to 7, provide excellent grinding preparations and structures if they according to the invention are incorporated into phenolic resin binders.

The thermoplastic polyhydroxyether can be one or more Fillers, opacifiers, extenders, Contain colorants or other additives common to thermoplastic resins. These preparations can be used according to the thermoplastic materials using conventional mixing processes.

Thermosetting resins obtained by incorporating a thermoplastic Polyhydroxyethers can be improved in their strength at room temperature and at elevated temperature, are those resins commonly used in abrasives. Typical thermosetting resins are phenol-aldehyde, Amine-aldehyde and modified, e.g. amine-modified Phenol-aldehyde resins. According to the invention, both novolaks and resols are suitable, the former in combination with Hardening agents. A complete description of suitable resins can be found in Robert W. Martin's book "The Chemistry of Phenolic Resins "(published by John Wiley & Sons, 1956) and in the book by T.S.Carswell" Phenoplasts "(published by. Interscience publishers, 1947). These and others thermosetting resins are disclosed in U.S. Patents 2,559,664, 2 779668 and 2 521 911.

The term "phenol-aldehyde resin" as used herein refers to acidic or base catalyzed thermosetting resins of the resole or novolak type, which are formed from a phenol such as phenol, cresol, xylonol, p-tert-butylphenol, p- Phenylphenol, bephenols and resorcinol and an aldehyde such as formaldehyde and

BAD OBiQlNAt

¹³ '009824/1 * 35

- ίο -,

Furfural; see the US patents * 2,585,196; 2,475,587; 2,557,922; 2,617,785; 2 675 335 and 2 551 025.

The abrasive articles or articles of the invention are made in a "preferred manner" by mixing together a liquid resole resin or resin solvent, a solid, powdered novolak resin mixed with a hardening amount of a methylene group-generating hardener, and the thermoplastic polyhydroxyether and abrasive grains Abrasive grains include metal oxides, particularly aluminum oxides, for example No. 12, No. 14 or No. 16 mesh size, natural corundum and diamond, although any other abrasive grains such as silicon carbide coated with a wetting agent are also used The wetting agent for the grains can be a liquid thermosetting resin or a resin solvent, vyie furfural, or a mixture of furfural and cresol, or a solution of a thermoplastic polyhydroxy ether. This mixture is pressed into a mold and the binder is hardened due to the effect of the hardness ungsmittel or the self-reaction of the resin cured. In this context it is noted that the term "heat" in "thermosetting" should also include room temperatures (eg 25 ^° C.).

The abrasive preparations and abrasives of the present invention can contain up to about 200 parts per 100 parts by weight of the thermosetting resin binder of conventional fillers such as cryolite, fluorspar, magnesia, silica, and other known modifiers. The greater flexural strength of the abrasives of the present invention may be indicative of greater tolerance for such modifiers.

The abrasives of the present invention are usually made in a manner conventional for known materials , with the exception of the use of the thermoplastic polyhydroxyether.

'' 00 9 8 2 ^{4/1 8 3 5 BAD} o RiQlNAL

- 11 - ■.: ■■ -:

Previously known abrasives, such as grinding wheels, wgxien im generally made from "grit", e.g. 780 parts ge *? melted AIpO, (each 260 parts of a mesh size of No. 12, No. 14 and No. 16) the filler, e.g. Cryolite, and Harz- '. binder (120 parts). The binder consists of solid material and liquid wetting agent, usually in a proportion of about 80 parts of powdered resin binder and about 40 parts liquid resin binder. In another well-known In the formulation, the binder consists of 120 parts of solid resin and about 10-20 parts of furfural as a wetting agent. The abrasive mix is mixed to a free-flowing mass by first coating the abrasive grit with the liquid binder (wetting agent) at room temperature. The gryolite filler and the one with sufficient hardening agent, such as hexamethylene

.tetramin, mixed powdery binders are mixed, and this dry mixture is circulated with the wetted semolina. The agglomerates are made by passing them through a sieve crushed. The abrasive should remain free flowing until the time it is added to the mold.

The thermoplastic polyhydroxyether can be used in an amount of up to 60% by weight, based on the thermosetting resin binder, to produce the abrasives according to the invention. For easier handling and to achieve optimal properties, preferably 0.5-50 $ polyhydroxy ethers are used. Maximum strength at high temperatures (260 ⁰ G.) and room temperature. (25 C <) are achieved by using 5 * -25 $ thermoplastic polyhydroxy ether, and the preparations within this range are particularly suitable for use as grinding wheels. . .

In one embodiment of the present invention Abrasive preparations made by using abrasive grit with a Potentially thermosetting or thermosetting resin containing the polyhydroxyether mixes, so the powdered

009824/183 5

thermosetting resin with a tableted, finely divided or powdery thermoplastic polyhydroxy ether circulated, mixed, ground in a screw mixer or otherwise intimately be mixed. Dry blends of the thermoplastic polyhydroxy ether and a potentially thermosetting one can be used Resin together with a hardening agent before or after pulverizing the mass to make abrasives getting produced. ■

"Snagging", as defined on page 909 in the "Tool Engineers Handbook" (published by NcGraw-Hill Book Co., Inc., New York City), is primarily a process of removing metal by the application of manual pressure by the Processor and is used extensively in foundries, welding shops and forges to grind pouring funnels, troughs, steam supply lines, pipe connectors, burrs and protruding welders' elevations. It is also used in rolling mills for rough grinding of slabs, billets, pre-rolled iron bars and blocks, where hard or strong grinding wheels with organic binders are used.

The preparations according to the invention are not only suitable for the production of grinding and metal grinding wheels, but also in other grinding elements, such as high-performance sand and polishing belts, cones, discs, etc.

The following examples illustrate the present invention without limiting it. Unless otherwise given, all parts and percentages are parts by weight and

example 1 Manufacture of test abrasives

a) Manufacture of dense metal abrasives

Weight "parts

Grit, molten aluminum oxide (Al ₉ O,) (mixture of 260 parts each with a size of No. 12, No. 14 and No. 16 780

009824/1835 _BAD qricmnal

Parts by weight

Cryolite (filler) 100

liquid phenolic resin 40

powdered resin 80

1 = 1-stage phenol-formaldehyde resole resin;

100-3000 cps. at 25 C

2 ■ == ■ 2-stage phenol-formaldehyde novolak resin

and thermoplastic polyhydroxy ether in an 88:12 mixture (10 ^ hexamethylenetetramine, based on the total modified novolakJ

The resin portion of the formulation was divided into liquid and powdered divided into solid phenolic resins. In the comparative system, 40 parts of liquid phenolic resin and 80 parts of powdered phenolic resin were used in making a free-flowing one Abrasive compound used. The amount of liquid and pulverized! Resin was adjusted to give a dry, free flowing mixture. .

b) Procedure

The liquid surfactant was added at 25 ⁰ C for abrasive grit in a metal pan and mixed with a spatula, was wetted until each grain semolina. A mixture of cryolite filler and the powdered resin mixed with enough hexamethylenetetramine to cure the novolak resin was passed through a sieve three times and placed on a piece of Kraft paper. The moistened semolina was then poured onto this dry powder mixture and coated by hand by rotating it with a swing arm on the Kraft paper and mixing. The agglomerates of the original mixture were broken up by passing them through a large mesh sieve. The agitation on the Kraft paper continued until it was completely coated and little or no residual powdered resin remained. The proportion of pulverized liquid resin was considered correct when

009824/1835

the abrasive mix remained free flowing until the time it was poured into the mold.

Six equal parts of the mixture obtained were then each placed in a 15 x 2.5 x 1.25 cm hollow mold, smoothed out and cold deformed to a density of 2.93 g / ccm using a ramming pressure of 30 tons. The test abrasive was then cured using a standard 24 hour gradual cycle : 10 hours from 66-186 °; 12 hours at 186 ⁰ G and 2 hours for cooling.

Three abrasive articles were tested to ASTM-D-709-61, respectively according to its bending strength at 25 ⁰ C and 260 ⁰ C. The average values are given in the following table:

Table 2

pulverizing test temp.
⁰ C. Flexural strength; kg / cm polyhydroxy ether
modif. phenol
resin percentage resin 25th unmodified.
phenol
resin 373.8 improvement fine ¹ 25 · 248.5 388.5 50 rough 260 248.5 118.3 56 fine ¹ '260 112 163.8 6th ρ
rough 112 46

1 = micro-crushed, powder density 0.26-0.29 g / ccm

Sieve Analysis: $ 97-99 through 200 mesh sieve

2 = micro-crushed, powder density 0.43-0.4-7 g / ccm

Sieve analysis: $ 76-78> through 200 mesh sieve

3 = polyhydroxyether content about 12 »

The polyhydroxyether-modified phenolic resin with a Bulk weight (powder density) of 0.43-0.47 g / ccm gives one optimal balance of the improvement in strength at room temperature and at high temperatures compared to

009824/1835

heat-resistant, unmodified phenolic resin binders. at with a decrease in the powder density or the particle size of the resin, the strength remains at room temperature essentially constant, but the strength at high Temperatures fall progressively. With higher powder densities or coarser particle sizes, the strength of the with remains Polyhvdroxyäther modified phenolic material essentially constant, but the strength at room temperature increases.

Example 2

The effect of changing the ratio of powdered for liquid phenolic resin is given in table 3:

: 40 ¹ Tabel 3 148 kg / cm ²
160 ° C . «36 ² 217 Proportions of powder,
too runny. Phenol-
resin: parts : 26 ² , Flexural strength:
at 25 C. - 211 , 0 80 237, , 4 84 372, 94 415, ■ \ ₌ , 3 , o'V , Q unmodified phenolic resin

2 = phenolic resin modified with polyhydroxy ether.

Flow accelerators can also be used in the preparations according to the invention to reduce the melt viscosity for. ■ special end uses are incorporated. In addition Bisphenol-Ä and other phenols, such as e.g. Phenol itself and hexatriphenol.

Example 3 .

Phenolic resin binder systems for abrasives can be made from one 2-stage covolak resin and / or a 1-stage resol resin getting produced. Will mainly just be a 2-step If novolak uses so is formaldehyde in any of its Forms, such as paraformaldehyde and trioxane or a compound, which contains available formaldehyde, such as a hexamethylene

009824/1835

Resole containing tetramine and methylol is required to create the cross-links necessary to thermoset the system to deliver.

In practice, however, the grinding wheel industry prefers 2-stage phenolic compounds hardened with hexamethylenetetramine Novalak binder; The effect of novolaks modified with polyhydroxyether is given in Table 4, the data for the flexural strength using the grinding wheel preparation and the curing conditions of Example 1 contains different amounts of hexamethylenetetramine and polyhydroxy ether:

Table 4

Polyhydroxy- ° ß> Hexamethy-
ether in lentetramine
Phenolic novolak *
resin 7th Flexural strengths: kg / cm at
25 C 260 C ratio ** 36.4 7.0 - 10 253.4 148.4 , ¹ . ^6th - 7th 237.3 64.6 7.0 12th 10 443.6 235.2 1.8 12th 7th 443.1 117.6 4.2 20th 10 353.5 213.5 2.2 20th 469.0

* = #, based on the weight of the modified novolak

** = ratio of flexural strength at room temperature (25 C) to flexural strength at 260 C.

A hexamethylene tetramine content of $ 10> provides an optimal balance between the flexural strength at room temperature and elevated temperatures for abrasive wheel-type abrasives. Good "high-temperature" skills are required.

When using abrasives in foundries, are however, higher strengths at room temperature and lower strengths at elevated temperatures are necessary. the

00982A / 1 835

Use of a lower hexamethylenetetramine content provides agents with a higher strength ratio at room temperature versus elevated temperatures.

The use of a hexamethylenetetramine content above 10 fo results in lower strengths at room temperature and the same or lower strengths at elevated temperatures. For general purposes, however, polyhydroxyether modified 2-stage phenolic resins with a hexamethylitetramine content between $ 3-20 are suitable as grinding wheel materials.

Example 4

The effect of the concentration of the thermoplastic polyhydroxyether on the flexural strength of grinding wheel preparations is given in Table 5, with the grinding wheel base preparations and curing conditions of Example 1 with the exception of a changed polyhydroxyether content. were turned »

Tabel 5 'C fo increase at 26O ⁰ C # Increase io polyhydroxy ether in liovolak preparation Flexural Strength: kg / cm ^ 130 9 - - Comparison, (no at 25 9 202, 3 55 Polyoxyether) 26th 186 9 43 5 * ..- ■ ν; 227.5 44 189 7th 45 9 .- ■ ♦ 247.1 81 - 149, 1 14th 15 * 286; 3 77 198 8th 52 50 *, 326.9 83 224, 0 71;. 10 ** 411.6 12 ■ '**' 401.8 414.1

* Β of ₀ Polyhydroxyäther and the novolak resin were mixed at 82-121 in a hot two-roll mill.

* ♦ β the polyhydroxyether was finished after production of the novolak in the reaction vessel before isolating the novolak by adding a hot molten salt through the Added to the distillation flask.

009824/183

BATH ORIGINAL

• - 18 - '

As can be seen from Table 5, the addition of the hot melt solution of the polyhydroxyether to the phenolic novolak is more effective and is therefore preferred for modification.

Improvements can be made with a polyhydroxyether content between $ 0.25-50 based on the weight of the phenolic novolak. The preferred range of polyhydroxy ethers is between about 5-20% by weight.

Example 5

The effect of the various polyhydroxy ethers on the heat resistance of grinding wheels is shown in Table 6, the samples being prepared according to the procedure of Example 1.

Table 6

ia polyhydroxy
ether in novolak
preparation Flexural Strength: kg / cm 'G % at 26'
increase 130.9 o ° io ■ 1
increase ^f o preserved
Strength
at Zim-
mertemp. at 25 opposite to
comparison 26 186.9 opposite to
I forget Comparison: 0 # 31 217.7 - 57 9 ¹ 227.5 14th 184.1 43 65. 10 ² 286.3 24 220.5 66 73 9 ³ 298.2 41 71 9 ⁴ 259.0 69 78 282.8

1 = a polyhydroxyether derived from biaphenol-A

(Melt flow 1-6)

2 = a polyhydroxy ether derived from bisphenol A base

(Melt flow 30)

3 = one of 1,2-bis- (p-hydroxyphenyl) -1-methy1-4-isopropyl-

cyclohexane-derived polyhydroxy ether

4 = polyhydroxy ether. derived from Biaphenol-A

(Melt flow 1-6) plus 4 $> phenol-blocked toluene diisocyanate as crosslinking agent.

Q0982W1835

The heat resistance of a test abrasive is indicated by the. Flexural strength at elevated temperature (26O ⁰ C) 'and the .bewahrte, percentage Festigkeit'bei room temperature when tested hot. Thus, it is believed that a resin which provides higher strength at elevated temperatures and / or a higher percentage of retained strength at room temperature will also provide greater heat resistance in the abrasive.

Greater heat resistance, both by strength measured at elevated temperatures as well as by the percentage retained strength at room temperature, are obtained with a polyoxyether of a lower value Molecular weight (higher melt flow) and a crosslinked polyhydroxy ether with low melt flow.

Example 6

The effects of the curing times of the resin and the Temperature changes are shown in Table 7, the preparation of Example 1 with an unmodified novolak

compares.

BATH

00982A / 183 5

Tabel

final curing stage

resin

Flexural Strengths: kg / cm '

at

Increase at 260 C

$ $> preserved strength increase at room temperature

co co cn

12 hours at 185 C -σ-

12 hours 6 hours

at 185 C -ο,

at 185 C

6 hours at 185 ^° C. and 4 hours at 232 ^° C.

undead . Novolak

237.3

preparation

v. Example 1 372.4

"345.8

"350.0

148.4

57 217.0 47 46 211.4 43 48 245.7 66

62

59
62
70

1 = initial curing of 65.5 ⁰ C to 185 ⁰ C in 10 hours

cn σ? co

The usual cure cycle, which requires a 12 hour hold at 185 °, has been found to be one , optimal balance of strength at room temperature and increased temperatures for the unmodified NOVölak comparison material results.

However, the resin modified with the polyhydroxyether gave the same "relative improvement in strength with a shorter cure cycle and significantly higher (SGf ₀ ) strengths at elevated temperatures with a higher peak temperature for post cure. Furthermore, the higher final cure cycle gave a higher percentage of retained." Strength at room temperature «

Example 7

The heat resistance of that described in Example 1, with Polyhydroxyether modified preparation was with a unmodified novolak resin compared. Those shown in Table 8 Data illustrate that the heat resistance of the polyhydroxyether modified novolak resin (measured by the strength at elevated temperatures) is much higher is, and that the modified Fovolakharζ is more stable than the unmodified. regardless of the particular curing cycle of time and temperature, the strength was at increased Temperatures with the modified resin by 40-100 $ higher than with the unmodified material.

0Ö9824 / 1835

1 SBiSH

-, 22 -

Table 8

Final curing stage Flexural strengths at 260 C: kg / cm

unmodified with polyhydroxy ether modified. Novolak novolak

149 ⁰ G - 4 hours 199.5 154.7

185 ⁰ C - 2 hours 216.3 95.9

4 hours 228.0 113.4

8 hours 228.4 93.1

204 ° C - 4 hours 230.3 156.8

8 hours' 233.8 128.8

238 ⁰ C - 2 hours 205.1 170.8

4 hours 256.2 184.1

₀ 8 hours 253.4. 195.3

272 C - 2 hours 216.3 172.2

4 hours 233.1 165.9

8 hours 240.8 173.6

1 = initial hardening from 77-174 ° C in 8 hours

Example 8

For use in high performance grinding wheels Preparations, the sintered aluminum oxide grain in a mixture with the pdlyhydroxyäther-modified described in Example 1 Novolak contained compared with unmodified novolak resin. In addition, there were 20 parts of furfural with 3 parts Calcium oxide was used instead of the liquid resole resin of the preparation of Example 1. The data are given in Table 9:

Tabel resin 9 Flexural strength! kg / cm ⁵ C increase 260 < , 4 increase aluminum 25 ^C , 3 .148, , 0 oxide semolina unmodified
tes novolak 237, , 4 57 217, ,8th 47 melted Polyhydroxy
ether-modified
Novolak 3 ^# 372, ,8th 110 226, 6th 53 It 492,
AYl ,1·
18th 125
35 271, 85 ρ
sintered "roi-ynyuruxyi * ¹ "
modifiζ.Novolak *
50 9 8 534
24 /

1 =. "Aloxite" grain from the Carborundum Co.

2 - "Alundum 75 A" grain from Norton Co.

3 = Resole liquid wetting agent

4 = Furfural net center (20 parts) with 120 parts

powdered NOvolak

It has been found that certain high-performance grinding operations Abrasives with a lower percentage of voids (porosity) perform best. The use of heat and pressure (hot pressing) as opposed to pressure alone (cold pressing) speeds you up better resin flow and wetting of the grit, whereby the Porosity of the agent is reduced.

Example 9

For some high-performance grinding work, agents with a lower percentage of cavities than can be obtained by cold pressing are useful. A number of experiments were carried out in which the test samples were produced by hot pressing, since this results in improved resin flow and wetting of the grit, which reduces the porosity of the agent obtained. The preparation described in Example 1 was used, which, due to the hot deformation for 10 minutes (157-16O ⁰ C) instead of cold pressing, had a density of 3.03 g / ccm. However, the usual 24 hour cure cycle of Example 1 was the same. Instead of the liquid resole in the preparation of Example 1, furfural (20 parts) and calcium oxide (3 parts) were also evaluated. The results are given in the table:

009824/183

I ι

Table 10
Test flexural strength: kg / cm '

Wetting agent p _ ^ ____

component _semolina $ emp .: unmodified. Polyoxyether % increase in

Modified novolak. Firmness "- - - 'Novolak

liquid gesehmol-

Resol Zen 25th 122.5 260 86.1 Furfural Il 25th 162.4 260 109.2 liquid
Resol minded
tert 25th 145.6 260 101.5

189.0
93.1

273.7
123.9

301.0
139.3

100 • 37

Regardless of the type of wetting agent or grit used, the polyhydroxyether modified novolak resin provided a 55-100 "strength improvement" at room temperature over unmodified novolak using liquid resole or furfural as the wetting agent component. The strength improvement ranged from 8-37 %

009824/1835

Claims (8)

Abrasive mixture consisting of a major amount of abrasive grains and a binding amount of a thermosetting one Resin binder, characterized in that the mixture contains up to 60 parts by weight of a thermoplastic polyhydroxyether the formula: -O-E- 0 " contains, in which D for Hesi; a dihydric phenol E stands for a radical containing hydroxyl groups of an epoxy and η means the degree of polymerization and has a value of at least 30 per 100 parts the thermosetting binder. 2. Mixture according to claim 1, characterized in that the The abrasive is aluminum oxide. 3. Mixture according to claim 1 and 2, characterized in that the thermosetting resin binder is a mixture of one liquid resole resin and a novolak resin in admixture with a curing amount of a "curing agent" providing methylene groups. 4. Mixture according to claim 3 »characterized in that the Novplak resin is a phenol / formaldehyde resin and the curing agent is hexamethylenetetramine. 5 «mixture according to claim 1 to 3, characterized in that that the dihydric phen oil is 2,2-bis (4-hydroxyphenyl) propane and the Bpoxide is epiochlorohydrin. 6. Mixture according to claim 1 to 5, characterized in that it is shaped and hardened ÖÖ9824 / 1835 7. Mixture according to claim 1 to 5, characterized in that that the mixture is present as a grinding wheel. 8. Mixture according to claim 1 to 7, characterized in that it contains 0-200 parts of filler, preferably gryolite, per 100 parts of the thermosetting resin binder. 009824/1835