JPS5835780B2 - Mold manufacturing method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a casting core and a mold.

Many different types of binding materials are used to make casting cores and molds.

Upon curing, the bonding material is required to impart various desired properties to the core and mold.

Such properties include, for example, corrosion resistance, moisture resistance and collapsibility or dumpability.

In core formation or mold formation, it is desirable to increase productivity.

Modern core forming and mold forming techniques have used unsaturated drying oils derived from natural products as bonding materials.

Linseed oil is a typical example of a drying oil.

When exposed to air, linseed oil and other unsaturated oils undergo oxidative incipient polymerization to form solid, highly crosslinked structures.

Polymerization can be promoted by thermal or chemical methods.

These bonding materials are known in the industrial arts as core oils.

In core formation, the core oil is mixed with sand and the sand mixture is formed into the shape of a core or mold.

Curing is accomplished by heating or aging the core or mold for an extended period of time.

In addition to the core oil component, binders based on core oil contain other components such as esters derived from the oil, unsaturated hydrocarbon resins, and solvents.

Core oil methods for forming molds such as molds and cores have been known for 50-60 years.

Methods more advanced than the core oil method described above have been introduced for 25 to 30 years.

These methods require heat curing of the bonding material.

These hot-box core methods are based on thermosetting resin compositions.

Chemically, these thermosetting resins include phenol-formaldehyde resins, urea-formaldehyde resins, and furfuryl alcohol-formaldehyde resins.

In addition to using heat to cure or polymerize these materials, acids are often used as catalysts.

Over a decade ago, cold, high-speed methods were introduced for the production of casting cores and molds.

The binders formed by these methods are based on urethane chemistry.

Essentially, the bonding material consists of two liquid resin components.

The first component is a phenol-formaldehyde resin.

The second component is a high molecular weight isocyanate.

Phenolic and isocyanate resins can be mixed with sand and used in a "cold box J" or "nobake J" system.

In a cold box system, sand coated with two components is blown into a corebox.

As the sand mixture is blown into the core box, a gaseous tertiary amine is passed through the core box to form a binder that causes instant hardening or solidification.

This technique is described in US Pat. No. 3,409,579.

In the method of making "no bake" type cores,
The entire polyisocyanate component, phenolic resin component, and catalyst are simultaneously mixed with the sand.

The sand mixture is then poured into the core box or pattern.

The sand mixture remains fluid for a period of time.

After this period, the catalyst begins to cure or polymerize and the core is rapidly formed by the binding materials that make up the binder reacting rapidly to form the urethane binder.

For no-bake binders, see U.S. Pat. No. 3,676.
It is described in the specification of No. 392.

Other binding compositions for making mold binders (bindi-ng
compositions and methods are described in US Pat. No. 3,879,339.

This US patent describes a cold box, ambient temperature, gas curing process to form a mold binder that includes an acid-curable organic resin and an oxidizing agent.

This bonding component is cured with sulfur dioxide gas.

The combination of sulfur dioxide and oxidizing agent leads to the formation of sulfuric acid, which cures the acid-curable organic resin.

Originally, sulfuric acid would be generated in situ and the acid would react with the resin.

For this purpose, curing of the bonding composition is achieved.

However, the above-mentioned template binders do not have such utility and versatility from the standpoint of being versatile or non-substituting template binders.

Either way, they have certain advantages and disadvantages.

It is an object of the present invention to provide novel binders that have not hitherto been chemically applied in castings or in other areas of binder application.

Further, the object of the present invention is to provide a cold hardening method that exhibits rapid curing.
Provides a box-type mold binder.

Another object of the invention is to provide a cold box binder useful in casting aluminum and other light metals.

The present invention preferably uses a binder that cures at room temperature.

The binder consists of (a) a binding material and (b) a free radical initiator.

The former binder materials include ethylenically unsaturated monomers, ethylenically unsaturated polymers, mixtures of such unsaturated monomers, mixtures of such ethylenically unsaturated polymers, and mixtures of such unsaturated monomers and polymers. and the latter free radical initiator consists of a peroxide and a catalytic agent.
agent).

Generally, the present invention uses cold curable bonding compositions that are polymerizable via free radical initiation and chain extension.

These bonding compositions are used in adhesive materials, especially particulate solids.

In particular, the present invention applies to sand or other aggregates.
s) to form molds or cores for metal casting, including in particular aluminum and other light metals.

Molds and cores made with these binders exhibit excellent collapsibility when used with light metals, ie, metals cast at low casting temperatures.

Curing of the bonding material formed into the bonding agent is performed at ambient temperature;
This is accomplished by a free radical initiator consisting of a peroxide and a catalytic agent.

In a preferred form, the catalytic agent is gaseous so that curing is accomplished very instantaneously.

However, the selection of different catalytic agents can be varied arbitrarily with respect to the method and cure rate.

The present invention relates to mold binders that are different from the chemical means used to form any binders conventionally known in the foundry industry.

The binder also has application as a binder in fields other than the foundry industry.

The chemical means underlying this bonding agent are based on coating materials (see, e.g., GB 1,055,242) and adhesives (e.g., Loctite Corporation).
ite Corporation)).

anaerobica based on similar chemical means
lly) Hardened mold binder is Canadian Patent No. 1,053,
It is described in the specification of No. 440.

This binder is very slow to cure and requires heating to achieve cure.

The present invention does not include an airless curing method, but does include rapid, almost instantaneous curing at room temperature using some kind of catalytic agent.

Molds, i.e., cores and molds, are formed by sprinkling sand or other aggregate with a binding material or chemical, shaping the sand into the desired mold, and curing the binding material or chemical to form the binding agent. It is known to be made by

The present invention can be directed to a binder obtained from combining two components together.

The first component (component I) is a binding material or composition that provides polymerization and crosslinking to hold or bond the sand or other aggregate in the desired shape.

The second component (component ①) is a substance that causes the polymerization and crosslinking of component I.

This component (1) material can be referred to as a "free radical initiator."

"Crosslinking" described here refers to the chain formation (-chai) that occurs when a polymer is bonded to another polymer or monomer.
n buildup).

Also, "polymerization" as described herein includes "crosslinking", but is also meant to apply to chain extensions involving only monomers.

Component (1) of the binder system can be described as an unsaturated composition that can be crosslinked or polymerized by a free radical mechanism.

Unsaturation occurs in terminal groups or side chains (
pendent ) is preferred.

Internal unsaturation is acceptable and polymerization occurs in combination with component (i).

Depending on the means of synthesis of component (1), it is also possible to use component I with terminal and/or side chain unsaturation and internal unsaturation in the same component.

The polymerization mechanism appears to be similar to the free radical type when it involves crosslinking compositions (ie, unsaturated polymers).

When certain monomers are used in the binding composition, a portion of the polymerization can occur by mechanisms other than free radicals.

To this end, although in the present invention the mechanism for polymerization may be conveniently used, the "free radical mechanism" is likely to be used in almost all cases; however,
Besides the free radical mechanism, other mechanisms in polymerization can also be involved under certain circumstances.

Curing is accomplished using a component consisting of a peroxide and a catalytic agent: a free radical initiator.

Unsaturated reactive monomers, polymers, and mixtures thereof can be used as flash-curable bonding materials in certain catalytic options for free radical initiators.

The unsaturated groups in the monomer and polymer are preferably of the ethylenic type.

For example, reactive polymers which can be described as oligomers or as adducts containing preferred vinyl or acrylic unsaturation can be used as bonding materials to make a bond for foundry cores or molds formed from sand during polymerization. use

Free radical initiators (component ■) are reactive polymers or monomers (
When mixed with component I), the binding material polymerizes to form free radicals which form the binding agent.

This combination of a peroxide and a catalytic agent that produces energy other than chemical properties can also be referred to herein as a free radical initiator.

The free radical initiators described herein can be used to polymerize component materials by a number of means.

For example, peroxide can be mixed with this mixture homogeneously mixed with the component I material and sand.

After shaping the sand into the desired shape, the shaped sand can be exposed to a catalytic agent.

Alternatively, the catalytic agent can also be added to component I and this mixture used to coat the sand, and the coated sand can then be shaped into the desired shape.

Next, the peroxide component of the free radical initiator is added to the compact;
It can be cured by the formation of polymerization.

Also, the component I material can be divided into two parts.

The catalytic agent can be added to this first part and the peroxide can be added to the other part.

When these two parts are combined. Polymerization occurs after interacting with the material to be bonded to at least one portion.

Depending on the catalytic agent or the equipment used and the type of application, this last method is not practical.

However, this last method can be used especially if the bonding material is used for bonding non-particulate materials.

The selection of various catalytic agents is significantly influenced by the means that can be used to polymerize the bonding material and the rate at which the bonding material is cured.

For example, a suitable catalytic agent may be selected by the user of the bonding material to polymerize the material instantaneously at ambient temperature, or to delay polymerization for a period of time and finally accomplish polymerization at an elevated temperature.

The effectiveness of the selection for the selection conditions for polymerizing the binding material appears to be important.

As mentioned above, the component I binding material is a polymerizable, unsaturated monomer, polymer or mixture of such monomers and such polymers.

Suitable monomeric component materials for component I include, for example, a wide variety of -functional, difunctional, trifunctional and tetrafunctional acrylates.

Representative examples of these monomers include alkyl acrylates, hydroxy alkyl acrylates, alkoxy alkyl acrylates, cyano alkyl acrylates, alkyl methacrylates, hydroxy alkyl methacrylates, alkoxyalkyl methacrylates, cyanacrylic methacrylates, N-alkoxy methyl acrylamide, and N-alkyl acrylates. -Includes alkoxy methyl methacrylamide.

Difunctional monomeric acrylates include, for example, hexadiol diacrylate and tetraethylene glycol diacrylate.

Other acrylates that can be used include, for example, trimethylol propane triacrylate, methacrylic acid and 2-ethylhexyl methacrylate.

It is preferred to use polyfunctional acrylates if the monomers are to be bonded in a binder system.

When only monomers are used as binding materials, as described above, no crosslinking occurs.

Also, some mechanisms other than free radical mechanisms cause polymerization.

Unsaturated reactive polymers that can be specifically used to form the template binder include, for example, epoxy acrylate reaction products, polyester/urethane/acrylate/reaction products, polyether acrylates, and polyester acrylates.

Unsaturated polymers used as component (1) include, for example, commercially available materials such as Uvitane 782 J and Uvitane 783, thiokol and acrylated urethane oligomers and acrylic polymers from CMD 1700J. and "Celard 3701J acrylated urethane, an acrylated epoxy resin available from Cel aness."

Reactive polymers can be made in many ways.

One suitable method of producing the reactive polymer is to react a polyhydroxy compound or polyol with a diisocyanate to form an incyanate-terminated prepolymer.

Additionally, this prepolymer is reacted with a hydroxyalkyl acrylate to form an oligomer.

Another method is to use a polyunsocyanate compound, -
Preferably, the isocyanate compound is reacted with a hydroxyalkyl acrylate.

The reaction product is an adduct of these two materials.

Furthermore, oligomers and adducts can be produced simultaneously under appropriate conditions.

In addition to the reactive unsaturated polymer, a reactive solvent can also be included, preferably as a component of the bonding material.

Also, inert solvents can be used, although this will affect the properties of the unsaturated bonding material.

Preferred solvents are unsaturated monomeric compounds such as the monomeric compounds described above or the Monomeric Component I materials.

The Component I material therefore consists of a mixture of these unsaturated monomers and the unsaturated polymers described above for use as the Component 1 material itself.

Best results are obtained when solutions of unsaturated reactive polymers and monomeric unsaturated solvents are used.

This combination is prone to copolymerization and cross-linking to bond sand or other aggregates together to form casting cores or molds, or to form the bonding matrix needed to bond other materials. do.

As mentioned above, in addition to the unsaturated polymer, it is preferred to use an unsaturated monomeric compound as a solvent in component I of the binder system.

As mentioned above, these monomers contain unsaturation and, in addition to acting as solvents for unsaturated polymers, form crosslinks with the polymers.

Also, any of the unsaturated monomers (or combinations thereof) mentioned above used as the Component I material itself can be used as a solvent.

Ethylenically unsaturated compounds of the vinyl or acrylic type are preferred.

Preferred monomers used as solvents for unsaturated polymers include, for example, pentaerythritol triacrylate, trimethylolpropane triacrylate,
, 6-hexanediol diacrylate, and tetraethylene glycol diacrylate.

The amount of monomers in component 1 can be in proportions from 0 to 100% relative to the total weight of component I binding material.

Component I A free radical initiator containing a reactive polymer as the material and an unsaturated monomer present on the unsaturated polymer without any solvent may be used.

Component I Materials - Although the same unsaturated monomers are used as free radical initiators, it is desirable not to use reactive polymers to obtain the polymeric binder.

Both of the above two combinations are not preferred.

As mentioned above, a preferred binder system is for a component I consisting of a reactive diluent, preferably a reactive unsaturated polymer dissolved in a monomerically unsaturated solvent, and a free radical initiator.

Free radical initiators consist of two precepts.

As a precept, organic peroxides are preferred.

However, any substance that generates free radicals when exposed to a catalytic agent can be used as the first component, including the free radical polymerizable component described above. Can be used with mixtures.

Peroxide levels can vary over a wide range, depending in part on the catalytic agent used.

However, generally 0 relative to the weight of the binding material - (component I)
．． 5-2% peroxide provides satisfactory binding under most conditions.

Examples of preferred peroxides include t-butyl hydroperoxide, rimene hydroperoxide, and methyl ethyl ketone peroxide.

Hydroperoxides are the most preferred peroxides.

Curing of unsaturation is observed when using peroxides.

Mixtures of peroxides and hydroperoxides can be used.

The catalytic component of the free radical initiator is preferably chemical in nature, preferably gaseous sulfur dioxide.

Other catalytic agents of some practical utility include amines and NO2.

Changes in catalytic agents affect the rate of polymerization.

However, other non-chemical substances which interact with the peroxide component of the free radical initiator can also be used advantageously.

For example, a moderate minimum temperature of 60.0° C. (below 140° C.) can be applied with the peroxide to form free radicals that polymerize the Component I material.

As the temperature increases, polymerization increases and cures quickly.

Polymerization occurs without the presence of chemical catalysts.

In a preferred molding operation, an unsaturated reactive polymer,
The monomer or mixture thereof and the peroxide component of the free radical initiator are mixed with the sand by conventional means.

This sand mixture is then compacted into the desired mold and formed by blowing or other known foundry core and mold forming methods.

The shaped body is then exposed to a catalytic material component of the free radical initiator.

In a preferred method of the invention, gaseous S02 is used as the catalytic agent of the free radical initiator.

This gas is present in catalytic amounts as described above.

The time that the sand mixture is exposed to such gas can be as short as 1-72 seconds or less, and the bonding material is cured by contact with the catalytic agent.

When SO2 is used as a catalytic agent in a foundry cold-box process, it is suspended in a carrier gas stream by known means.

Generally, the carrier gas is N2.

A small amount of SO2, such as 0.5% relative to the weight of the carrier gas
is suitable for polymerization.

It is also possible to add SO to the bonding material without the presence of any carrier gas.
2 can be exposed.

In addition, component (2) can contain any desired component.

For example, wetting and defoaming additives can be used.

Silanes have proven to be particularly useful additives.

Particularly preferred silanes are unsaturated silanes such as vinyl silanes.

The bonding material as a component of the mold bonding agent in the present invention has the following advantages: The bonding agent used for casting Nialuminum has excellent disintegrability.

This bond is easy to disintegrate and allows aluminum castings to be shaken out under the influence of minimal external energy.

Also, the binder has good strength. The pot life of the sand mixture of component (2) can be extended.

The surface finish of the mold can be achieved through the use of a bonding agent.
The process proved to be highly favorable.

The production rate of cores and molds made using the binder system of the present invention is particularly rapidly accelerated when SO2 gas is used as the catalytic agent.

Molding operations using the binder compositions of the present invention include component I and a free radical initiator, preferably a peroxide (component
) with sand or other foundry aggregate by known means.

This sand mixture is then formed into the desired mold, ie, core or mold, by known means.

The binder of the present invention is then formed by exposing the sand mixture to a catalytic agent, a second component of a free radical initiator, preferably sulfur dioxide gas, which immediately causes polymerization of the component I binder material.

Next, the present invention will be explained by giving examples.

In these examples, all “
Parts" are by weight, and all percentages are percentages by weight.

Example 1 Gel tests were conducted on various unsaturated monomers and polymers to determine their polymerization tendencies and rates.

In these tests, about 1.5-2 g of unsaturated monomer or polymer (i.e. component I) was mixed with 0.0:1 t-
Mixed with butyl hydroperoxide (peroxide component of the free radical initiator).

This mixture is then exposed to SO2 gas (a catalytic agent of a free radical initiator) with a force that disperses such gas into a liquid (bubbling) or to generate an SO2 atmosphere above the liquid (contacting).
Cool and expose.

The results are shown below. In this case, all unsaturated monomers and polymers are shown to be polymerized.

To this end, all the compounds listed below are potential binding agents.

Also, those compounds that exhibit fast polymerization or gelation are the greatest potential mold binders for use in mold molding to achieve fast cold box mold and core formation.

Hydroxy PBG-2000 (Hisdol Company) in Acetone 50% Unsaturated Hydrocarbon Resin Example 2 The unsaturated polymer was mixed with 1 mole of pentane diol and 4
It was made by reacting mol of hydroxy ethyl acrylate with 3.0 mol of toluene diisocyanate.

The reaction was accelerated using dibutyltin dilaurate.

A catalyst content of 0.14% based on the solid content was used.

Hydroquinone monoethyl ether was used as an inhibitor.

The reaction was carried out in a reaction medium (solvent) consisting of ethylhexyl acrylate and hydroxy acrylate.

In carrying out the reaction, a mixture of TDI and solvent was charged to the reaction vessel.

Pentane diol was added to this mixture followed by hydroxyethyl acrylate.

After the hydroxyethyl acrylate addition was complete, the catalyst was added.

The reaction was carried out under air sparge.

The reaction was carried out at 40-45°C for 2.1 hours, then the temperature was increased to 8.
The temperature was raised to 0-85° C. and the reaction continued for 4.3 hours, then 0.03% inhibitor was added and the reaction continued for half an hour.

The reaction product was allowed to cool.

This product was tested for non-volatiles and found to be 59.2%.

This corresponds to a theoretical non-volatile content of 60%.

The viscosity of the product was 6.0 Stokes.

Then 20g of unsaturated polymer was mixed with 1.6g of acrylic acid, 10.7f! of diethylene glycol diacrylate, 9.99 g of trimethylolpropane trimethacrylate and 2.0 g of vinyl silane.

Acrylic acid, diethylene glycol diacrylate and trimethylol propane triacrylate are unsaturated monomers.

This solution of unsaturated polymer and unsaturated monomer is designated as component 1.

1. ! 9 of t-butyl hydroperoxide, the peroxide component of a free radical initiator, was added to the solution of unsaturated polymer and unsaturated monomer.

Unidrone 5% sand (finely ground silica sand, washed and dried) was placed in a suitable mixing device.

Component I and the peroxide component of the free radical initiator were mixed into the sand until uniformly distributed.

Component I and state of superpolymerization slow, in contact with SO2 The oxide level was 2% by weight of sand.

The sand mixture was placed in a regular core cavity to make a standard tensile briquette test core known as "dog bones".
ty) or blown into a box.

The dock bone test cores were exposed to a free radical initiator catalytic component and cured.

Gaseous sulfur dioxide was used as the catalyst component.

The cores were exposed to the SO2 catalyst for approximately 1/2 second (gas time) and the catalyst was removed by purging with nitrogen for 15 seconds.

The tensile strength of the core is 15.61 when taken out of the box.
Ky/cffl (223psi), 14.41 Kt/cr/l (205psi) after 3 hours, and 5.96 Kp/m (227p) after 24 hours.
si).

A swing test was conducted on aluminum castings using the same "dock bone" as described above.

Seven tensile briquettes (dock bones) were placed in the mold.

This mold was incorporated into a gating system.

The mold was designed to make a hollow casting with metal on all sidewalls approximately 1/4 inch thick.

An opening was provided at one end of the casting for removing the core from the casting.

Approximately 70.4℃ (approximately 1
The aluminum melt at 300'F) was poured into the mold.

After approximately 1 hour of cooling, the aluminum casting was broken off from the sprue system and removed from the mold for shakeout testing.

The castings were placed in a 3.79z (i gallon) capacity container and tested for shakeout.

The container was placed on a vibrating machine and cartwheeled for 5 minutes.

The weight of the sand core thus removed from the casting was compared to the initial weight of the sand core and the swing-out rate was calculated.

After the vibration operation described above, the sand remaining on the casting was scraped off and weighed.

The sand cores bound by the binder were observed by shaking out 100 times.

No standard test was conducted for the above-mentioned swing test.

The tests used are useful for understanding the disintegration properties of binders and for comparing the relative disintegration properties of binders.

The percentages given are based on dispersion and are reliable readings.

Claims (1)

[Scope of Claims] 1 a) dispersing aggregate with a binding material consisting of an ethylenically unsaturated monomer; b) forming such aggregate into a desired mold; and C) dispersing said binding material with an organic filtrate. 1. A method for producing a template, characterized in that the polymerization is carried out under the action of a free radical initiator consisting of an oxide and a catalytic agent. 2. The method for manufacturing a mold according to claim 1, wherein the aggregate is sand. 3. The method of manufacturing a mold according to claim 2, wherein the bonding material is a mixture of an ethylenically unsaturated monomer and at least one other ethylenically unsaturated monomer. 4. The method of manufacturing a mold according to claim 1, wherein the catalytic agent is a substance having chemical properties. 5. The method of manufacturing a mold according to claim 1, wherein the catalytic agent is gaseous sulfur dioxide.
Method for manufacturing the mold described in Section 1. 6. Method for producing a mold according to claim 2, wherein the bonding material contains at least one ethylenically unsaturated polymer in addition to the ethylenically unsaturated monomer.7. suspended in the binding material and at least 0.5
The method for manufacturing a mold according to claim 5, wherein the mold is exposed for a second. 8. The catalytic agent is heated to at least 51.7°C (125'
Claim 5 which is heat of elevated temperature of F')
Method for manufacturing the mold described in Section 1. 9 The amount of said binding material is increased to io% by weight of sand.
A method for manufacturing a mold according to claim 5. 10a) dispersing the aggregate with a bonding material consisting of an ethylenically unsaturated polymer; b) forming such aggregate into the desired mold; and C) dispersing the bonding material with a free bonding material consisting of an organic peroxide and a catalytic agent. A method for producing a template, characterized in that polymerization is performed using a base initiator. 11. The method of manufacturing a mold according to claim 10, wherein the aggregate is sand. 12. The method of manufacturing a mold according to claim 11, wherein the bonding material is a mixture of an ethylenically unsaturated monomer and at least one other ethylenically unsaturated polymer. 13. The method for manufacturing a mold according to claim 11, wherein the catalytic agent is a substance having chemical properties. 14. The method of manufacturing a mold according to claim 11, wherein the catalytic agent is gaseous sulfur dioxide. 15 The catalytic agent is heated to a temperature of at least about 125°C.
Claim 1, which is heat at an elevated temperature of 'F)
A method for manufacturing a mold according to item 1. 11. The method for producing a mold according to claim 10, wherein the oligomer is a 16-unsaturated polymer. 11. The method for producing a mold according to claim 10, characterized by a 17-unsaturated polymer.