DE2040795A1 - Ceramic masses and objects made from them - Google Patents

Description

£. I. m PONT DE KSHOUBS AHD COMPANY 10th and Harket Streets, Wilmington, Delaware 19898, V.St.A.

Ceramic bodies and objects made from them

The present invention relates to slurries from which ceramic objects can be made «you Compounds contain a ceramic »particulate material mixed with an aqueous dispersion of an internally plasticized, thermosetting resin. These masses are raw ("green"; unfired) ♦ ceramic tapes deformed, which ultimately "where fired" rigid ceramic bodies are needed, e.g. B * in multilayer circuits, can be used for electronic purposes can. Through these slurry masses, many of the. to the known state of the art belonging brook parts overcome with the dimensional stability, flexibility, durability against weathering and compatibility with a large variety of conventional metallization pastes.

In the manufacture of ceramic objects, the Evaporation of volatile constituents from a digestive mass of inorganic substances has been made possible earlier

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brings. In U.S. Patent 2,486,410 (ftowatt) the Manufacture of leather-hard panels described, the finely divided ceramic materials and small amounts of organic, Contain solvent-soluble or water-soluble binders. The plates are in a leather-like, flexible shape only because some solvent or water is being retained. Vie, however, in U.S. Patent 2,952,877 (Park) is found, it is difficult to retain a sufficient amount of water in the plates during storage, to keep them malleable or to control dimensional features. In the above-mentioned patent 2,952,877 the use of a mixture is described which, in addition to a ceramic material (a) an essentially water-soluble, polymeric organic binder (e.g. polyvinyl alcohol), (b) a substantially water-soluble, compatible organic plasticizer for said binder and (c) a relatively small amount of water to allow calibration results in a highly viscous paste. Moses mixture became extruded into sheets and dried to before subsequent Pressing and firing into sintered products first of all flexible plates, the ceramic, particulate material contain to manufacture.

This latter method also had its problem ·. Careful monitoring of the water present is necessary in order to enable uniform extrusion. Careful drying conditions are needed »to prevent a loss of v <* f p.hm ^ fr + j > \ χ η $ n achf *?" * Gendy p loss of the extruded sheet »α * Bu extruded product has due to the loss dea verhaltnismägsig volatile organic plasticizer limited s tabl Ii did. Aueserdea must the extruded product at low humidity are stored, is dealt avoided

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BATH ORIGINAL

that the dried plate absorbs more water, which leads to poor control of the dimension merlaiale during the subsequent processing. Me is high water absorption naturally due to the use of practically water-soluble, polymeric binders and plasticizers. A later United States Patent 2,966,719 (Park) taught to avoid these difficulties of the water-based system by using a volatile, organic solvent system is used in which the tape after a Giessverfehren is formed. This method differs in particular from that of US Pat. No. 2,486,410 (Howatt), when the cast ceramic tape is made pliable by a thermoplastic binder resin that has been plasticized in a contractually plasticized manner, instead of being made pliable by solvent retention, In the case of the method according to US Pat. No. 2,966,719 is also the addition of an organic, solvent-based Reactive agent preferred.

This method according to the latter USA patent also suffers from various difficulties, some of which are characteristic of an organic solvent system are. These difficulties include potential pollution, flammability, and tossibility hazards · Also are the tapes are particularly sensitive to deformation when using very soft, thermoplastic binders in handling or rolling up for storage as the Polymers are subject to creep even with low applied stress. If an externally acting plasticizer is used, the slow volatilization of the Plasticizer to stiffening and curdling upon prolonged storage. In addition, the use of one results in organic-soluble, thermoplastic binder elements burnt-on tapes, which are highly sensitive to most organic solvents

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20A0795

PO 3645

One of the main uses of ceramic tapes is in the electron industry. Many electronic component manufacturers print their circuits onto the ceramic Tape before the tapes are burned. The solvent sensitivity of these tapes limits the choice of sum Printing specific masses that the manufacturer can use. Accordingly, the purpose of the present invention is to provide ceramic slurry compositions made without the above-described difficulties of the prior art methods belonging to ceramic tapes are set that can be burned to ceramic objects. In addition, the ceramic tapes and objects produced according to the invention are particularly useful in the Electron industry.

The present invention relates to a slurry mass, from which ceramic objects can be made. The slurry contains a ceramic particulate material mixed with a resin binder and is characterized in that the ceramic, particulate substance with an aqueous dispersion of an internally plasticized thermosetting resin is mixed. The slurry mass can contain small amounts of optional constituents « Contains parts such as emulsion stabilizers, wetting agents, leveling agents and anti-foaming agents

The invention also relates to a process for producing ceramic objects from a slurry, which is characterized in that (1) a For the production of ceramic objects suitable Aufechschlungemasee sets up, which contains a ceramic, particulate substance, which with an aqueous sieve ion an internally softened, tea-hardening Harsee mixed

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(2) forms a film of slurry called tLev on a smooth, bearing surface; and (3) heats the film to remove the aqueous medium and thereby produce a flexible KLIm loaded with a ceramic, particulate matter.

The novelty of the slurry compositions according to the invention lies in the use of an aqueous dispersion, an internally plasticized, thermosetting resin. An aqueous system is therefore used in order to avoid the troubles of an organic solvent system such as pollution of the atmosphere, flammability and toxicity. In addition, aqueous systems are much more convenient to make and subsequently handled, and ceramic articles are much easier to make from them than from organic solvent systems. The expression "internally plasticized, thermosetting resin ¹¹ denotes a known class of thermosetting resins. In general, a thermosetting resin is one which becomes non-flowable and insoluble when heated. This is in contrast to externally plasticized resins, in which an external plasticizer is present as part of a physical mixture that can be lost through volatilization, extraction or oxidation plasticized thermosetting resins provide better dimensional stability, better storage stability, better solvent resistance, and more permanent plasticized raw (unfired) ceramic articles than through the use of prior art hates.

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The internally plasticized, thermosetting resins according to the invention are medium to high molecular weight, water-insoluble polymers which, when films or sheets are formed from the slurry masses at room temperature, give tough, flexible films. Slurry compositions containing these resins also produce tough, flexible, crosslinked films or sheets for short periods of time (0.1 to 15 minutes) after heat drying at moderately elevated temperatures (50 to 150 ° C.). Polymers useful according to the invention are, for example, vinyl acetate copolymers which contain 5 to 50 % of an internally plasticizing comonomer, e.g. B. ethylene, butyl acrylate, vinyl 2-ethylhexoate, dibutyl maleate, and 0.5 to 10 % of a comonomer which is able to crosslink the polymer by heat treatment after polymerization (e.g. N-methylolacrylamide). Small amounts of the acidic Catalysts can also be present to accelerate the crosslinking reaction. Another group of more useful internally plasticized, toughening resins includes copolymers of acrylic acid esters !! with comonomers which can crosslink during drying, especially if they are heated. Acrylic acid esters such as "Bhoplex" E-32 or "Bhoplex" HA-8, which are described in Boehm & Haas Bulletin ΈΡ-125 &, are commercially available * This list of specific examples of suitable, internally plasticized, hit-hardening resins is not to be regarded as limiting or comprehensive. Other known, internally plasticized, thermosetting resins can also be used according to the invention. The thermosetting resin selected can have a high or low viscosity must but during dee firing to form rigid one, the ceramic body can deliver are volatilized · Also you must dae resin flexible films · thermosetting harp show a generally acceptable bending "" * ness when the initial modulus below 2110 kg / cm ² (JO 000 pel )

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PG 3645

A wide variety of ceramic materials can be used in the present invention. Suitable are inorganic substances, consisting mainly of alumina, steatite, zircon, Aluminiumsillcat _t Zikoniumdioxid, titanium dioxide, Hagnesiumsilicat, barium titanate, beryllia, etc., and various combinations thereof. Plus agents such as phosphates, borides or modifying oxides of lead, iron or tin can be added. »The ceramic materials selected for the slurry should have a small particle size, which should be in the order of 325 Haschen ™ or smaller. (The bag sizes here are taken from the US Standard Sieve Series, 1940 », which is in the Handbook of Chemistry and Physics, 36th edition« Chemical Rubber Publishing Co. »Cleveland, Ohio, USA, 1954-55 * pages 3078-3079 appeared.) Heinere particle sizes on the order of 325 hashes facilitate the formation of a dense 511 ms of ceramic, particulate! Material and assist in providing a dense, fired product desirable for electronic uses. Larger particles result in a fired object with significantly lower dielectric resistance, which is often porous or permeable in nature and even looks Λ broken or streaked.

Optional additives for the slurry masses include Wetting agents, anti-foaming agents, emulsion stabilizers and Leveling Aids · A wide variety of wetting agents for the ceramic particles can be used, e.g. B. Polyphosphates, Tetraphosphates, silicates, low molecular weight, organic ■ organic surface-active agents, such as substituted polyethylene glycols, or anionic organic surfactants such as sodium salts of higher aliphatic carboxylic acids (Sodium stearate). Water-soluble, high molecular weight substances

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are effective wetting agents for the ceramic particles and also act as building emulsion stabilizers. These include Carboxymethyl cellulose and its salts, hydroxyethyl cellulose, Methyl cellulose, polyvinyl alcohol, substituted polyvinyl alcohols, polyvinylpyrrolidone and proteinaceous substances (e.g. Casein). The wetting agent in the slurry facilitates the formation of homogeneous, uniform slurry masses, that have desirable spreadability * Without such Gown requires excessive mixing and uniform films free from defects are difficult to manufacture. Hit wetting agents will be the method of preparation of slurry masses and making them into elms surprisingly easy to do *.

The antifoam agents added to the slurry reduce air leakage and include compounds such as silicones, polyglycol ethers, higher alcohols, etc. The amount of the optional additive can be adjusted can be varied to the given requirements, as is known to the person skilled in the art *

The previously mentioned surfactants and antifoams which may be present in the slurry cups according to the invention are generally present in percentages by weight (based on the total pesticides present) of 0.001 to 5% or from 0.0001 to 3 % .

When carrying out the method according to the invention first the aqueous dispersion of the internally softened, thermosetting resin. Prepared beforehand, inner soft skin hardening resins can be used in Vasaer * be pergated, or it may be desirable that «polymerize the monomers directly in an aqueous dispersion will.

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If a pouring method is to be used for film formation, the viscosity of the dispersion should be below 1600 cps. (measured at 20.degree. C. in a Brookfield viscometer at 50,000 revolutions per millimeter), so that the viscosity of the slurry insulation compound according to the invention (which is a ceramic, particulate substance contains) is not too high for irrigation.

After the aqueous dispersion of the internally plasticized, thermosetting resins has been prepared, this dispersion is mixed with the ceramic, particulate material. Conventional methods of compounding! This slurry can be used; Die Hasse, however, must be mixed thoroughly until a homogeneous suspension is obtained in order to avoid undesirable streaking and breaks in areas of poor strength in the fired end product . avoid. In certain cases, when the resin dispersions are very stable and contain the surfactant at a fairly high level of concentration, the ceramic particulate can be added directly to the dispersions; this compounding process should be accompanied by agitation. Rope agglomerates can be broken up by agitation at high shear to ensure a smooth surface. However, to ensure that the addition of the ceramic particulate does not "shock" the aqueous dispersion of the polymer and cause coagulation, the ceramic particles are often first dispersed in water containing a wetting agent and optionally an anti-foaming agent. This ceramic particle suspension is then after a treatment with high shear forces and after the removal of air by blowing in the egg and in a vacuum mixed with the aqueous dispersion of the hardening resin.

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tenon slurry, wet after prolonged standing one there is little tendency for the ceramic, particulate matter to settle out. This is problem-free because of the particulate The material is easily damaged by gentle listening.

The ratio of ceramic particulate to total water in the slurry can vary considerably, but should be as high as possible, while still allowing the formation of a good dispersion and ceramic film from it. particulate matter to water reduces the shrinkage that occurs in the ceramic SiIm during firing. On the other hand, if the FLIa is to be manufactured by extrusion methods, a high viscosity paste is required and the water concentration should be very low. More precisely, if the unfired TiIm is made from the ceramic particulate matter and binder by casting methods such as coating with a hessian, viscosity values of the dispersion, e.g. B. from 300 cps. (At 100 revolutions per minute in the Brookfield visionosimeter) up to 1200 cps. Which has been found to be “ desirable. With the wide variety of coating methods available, viscosity values of 50 to 5000 cp (at 100 revolutions / flinate in the Brookfield viscometer) and up to 20,000 cp (at 10 revolutions / kinute in the Brookfield viscometer) can be used.

After the production of the * vf frrlP ffi- ^ ga-ff ψ ^λ , ** ** the same is deposited on a smooth surface as an ulm, plate or tape. As mentioned above, any conventional coating and / or corrosion method can be used. The IiIm is banned according to any conventional drying method (ultra-red, air drying,

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Oven heat) dried · To accelerate the drying process and to crosslink the thermosetting resin usually heat in the range of 50 Me 150 ° C applied. This type of drying generally only takes a few minutes · Different drying methods can be longer or shorter Need times.

The one still in contact with the supporting surface Film can be removed from the surface and further processing steps, such as coating, compression molding, pressing and the like · Alternatively, the film may, if it lies on a flexible, load-bearing surface, rolled up and stored in this way. These known methods are described in US Pat. No. 2,966,719 *

The invention is illustrated by the following examples. In the examples and elsewhere in the description, all percentages and proportions are used Substances or components based on weight. Venn additions in Drops are specified, 1 drop weighs about 0.025 g *

example 1

A slurry was prepared by adding a mixture of 190 g of alumina powder (325 mesh) and 10 g of talc to an aqueous dispersion which contained the following ingredients: (a) 20 g of a dispersion of. 75 * 5% vinyl acetate / 21 _t O% Itajlen / 3 »5 % H-methylol-acrylamide-terpolymares, which contained 46.7% polymer moisture, (b) 0.04 g taleSaaeikatalyeator, (e) 90 g H ^ p and (d) 2 drops of Antischäoaeittel (Hercules Ho. 540). She became the whole mix ia a · «Homoaiacer (device that works with high shear works) for 3 minutes. You became dispersion

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then deflated in vacuo, and the Brookfield viscosity was decided. It was 2380 cps. at 10 revolutions / minute and 630 cps. at 100 revolutions / minute.

The slurry was then spread on a Teflon plate poured under a rigid knife. After drying for 48 hours in air at tree temperature, the plate was wise, homogeneous, looked and pliable · Mn similar result was obtained when the plate was heated to 120 ° C for 5 minutes «

Example 2

A slurry body was prepared by adding a mixture of 190 g of alumina powder and 10 g of talc to an aqueous dispersion containing the following components: (a) 20 g of an aqueous dispersion of 75 _T 5% vinyl acetate / 21.0% lthylen / 3.5 % K-methylol acrylamide terpolymer containing 46.7 % polymer solids, (b) 0.15 6 trisodium polyphosphate surfactant, (c) 63 g water, and (d) 4 drops of antifoam (Hercules # 3W)). The entire mixture was blended in a homomixer (high shear device) for 3 minutes. The dispersion was then vented in vacuo and the Brookfield viscosity was determined. It was 2380 cps. at 10 revolutions / minute and 63O cps at 100 revolutions / minute.

The slurry was then placed on a Teflon plate poured under a rigid knifeBach 48hissem_Troeknen lh air at room temperature the plate was wise, homogeneous, tough and flexible. A similar result was obtained when the plate was heated to 120 ° C for 5 minutes.

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PC 3645
Example 3

Its slurry mass was obtained by adding a mixture of 190 g of clay and 10 g of talc to (a) 20 g of an aqueous dispersion which contained 80 % vinyl acetate / 17 % ethylene / 3 % N-methylolscrylamide terpolymer and had a polymer solids content of 49% % comprised "(b) 0.04 g oxalic acid catalyst and (c)? 8 g water produced" The results are similar to those of Example 2 ·

Example 4

A slurry mass according to Example 2 was produced with the modification that the internally plasticized, thermosetting Resin "X-Idnk" 2873, a product of ürma national Starch and Chemical Corporation, and that 130 grams of Vasser were added. The results were similar to those obtained in Example 2, although the film was somewhat weaker was

Example 5

A slurry according to Example 2 was prepared with the modification that the internally plasticized, thermosetting resin "Ehoplex" E-52, a self-crosslinking, acrylic resin dispersion containing 46 % solids (pH 3.2; Sohm & Haas Co.) t was; 110 g of water were required for the viscosity control. After pouring and drying the films, tough, flexible slimes were obtained which were similar to those of Example 2.

Example 6

In this example an alternative method to Heratel

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Development of this slurry illustrated in which the particulate matter prior to eventual mixing with the aqueous, thermosetting resin is dispersed

A mixture of 380 g of alumina powder and 20 g of talc was made into a solution of 160 g of water, 80 g of a 2% strength solution of "Methocel" (methyl cellulose, grade 90, BG-DG-40Q0 Dow Chemical Company) and 3 drops Antifoam agent (Hercules Hr. 357) given. The mixture was then subjected to a high shear force for 5 minutes and freed from dissolved and dispersed air by massive drilling for 10 minutes at 82 to 85 ° C., cooled to 45 ° C., and then evacuated while guiding at this lower temperature. The detachment of the bubbles was promoted by alternating evacuation and releasing the vacuum. After about 30 minutes the foam was completely removed. At this point, 40 g of an aqueous "Bhoplex" E-32 dispersion containing 1 drop of an anti-foaming agent was slowly added to the particulate dispersion with gentle stirring that no bubbles formed · Films were cast and dried; the results showed « that homogeneous, tough and flexible films can be obtained with this method.

cm χ 2.54 cm squares were made from the cast Films punched out and screen printed with conductive inks. The structure finally obtained became a printed one Circuit burned

Example 7

The dimensional stability and electrical properties of the ceramic items were tested erilndungsgemässen

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and found to be excellent »he results are given below in label I reproduced

On both sides of a 2.54 cm χ 2 _% 5 cm large, pre-baked ceramic fragment, a conductive button was produced by applying a silver mass by screen printing and baking it for 5 minutes at 750 ° C. The leads were soldered to demi using a lead / tin (6O / 4O) tmlttel. The loss factor was determined In general, values below 0.001 were considered satisfactory. The differential shrinkage was determined (the difference in the length and the width of the 2.54 x 2.5 x cm large, atv-punched elm after firing at 1650 ° G ).

Table I.

Sample KLfferen Loss Fairtor

For drying shrinkage tielle play (in%) shrinkage

(in %)

1 dried in air 20.0 * 0.0 0.0 0.0006 * 0.0001
and λητίπ burned

1 direct ge 20, β * 0.1 ° · 2 BLD. burns and
dried

5. Air dried 20.3 * 0.05 0.1 0.0005 * 0.00005
and then burned

5 in the air »MÄW 0.1 0.0005 * 0.00005 Set-dries
and ^ H f ^ yin
burned

The present invention thus results in an aqueous System provided unfired, ceramic flats, the excellent laying stability, flexibility »insensitivity

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resistance to solvents and moisture and compatibility with a wide variety of printing materials The inventive »fired ceramic articles are useful as substrates for the application of various circuit elements, which can be used in a variety of ways in the electronic field.

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1 09808/1539

Claims (1)

PC 3645 August 17, 1970 Claims Suitable for the manufacture of ceramic objects A slurry containing a ceramic particulate material bonded with a resin binder is mixed, characterized in that the ceramic, particulate material is mixed with an aqueous dispersion an internally plasticized thermosetting resin is mixed. Cohesive, pliable film that forms a rigid, ceramic Condition is combustible, characterized in that the film is an intimate mixture of a ceramic, particulate Substance with an internally plasticized, thermosetting resin contains · · A cohesive, flexible film according to claim 2, characterized in that the resin is crosslinked. Rigid object made by firing an object from the slurry according to claim 1 A method for producing ceramic objects from a slurry, characterized in that (1) a slurry suitable for the production of ceramic objects is prepared which contains a ceramic, particulate material which is mixed with an aqueous dispersion of an internally plasticized, thermosetting resin , (2) from said \ slurry body forms a film on a smooth bearing surface and (J) the film heated "to the aqueous medium to remove and thereby one with the - 17 - 109808/1539 ceramic, particulate matter laden, pliable Make film. 6 · Method according to claim 5 »characterized in that? step (3) in the temperature range from 50 to 150 ° C carries out - 18 -109808/15 39