EP0423780A2 - Novel heat curable organic resin foundry sand binder process - Google Patents

Novel heat curable organic resin foundry sand binder process Download PDF

Info

Publication number
EP0423780A2
EP0423780A2 EP90119969A EP90119969A EP0423780A2 EP 0423780 A2 EP0423780 A2 EP 0423780A2 EP 90119969 A EP90119969 A EP 90119969A EP 90119969 A EP90119969 A EP 90119969A EP 0423780 A2 EP0423780 A2 EP 0423780A2
Authority
EP
European Patent Office
Prior art keywords
epoxide
sand
resin
imidazole
curing agent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP90119969A
Other languages
German (de)
French (fr)
Other versions
EP0423780A3 (en
Inventor
Tom Cobett
Neil Markham
Ralf Teltschik
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GVT- GIESSEREI VERFAHRENS-TECHNIK GmbH
Original Assignee
GVT- GIESSEREI VERFAHRENS-TECHNIK GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by GVT- GIESSEREI VERFAHRENS-TECHNIK GmbH filed Critical GVT- GIESSEREI VERFAHRENS-TECHNIK GmbH
Publication of EP0423780A2 publication Critical patent/EP0423780A2/en
Publication of EP0423780A3 publication Critical patent/EP0423780A3/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
    • B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
    • B22C1/22—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins
    • B22C1/2233—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • B22C1/226—Polyepoxides

Definitions

  • the invention relates to epoxide or epoxide novolac resins mixed with a latent curing agent, with or without an accelerator, cured by heat for the production of foundry sand molds and cores. It is common practice to refer to these heat curable resin binders as “Hot Box” or “Warm Box” binders since the core box or pattern must be heated to affect curing of the sand, resin, curing agent and accelerator mixture.
  • the "Hot Box” and “Warm Box” processes utilize sand coated with a thermosetting resin in liquid form and a latent curing agent in liquid or dry powder form. This mixing of sand, resin and curing agent is done at ambient temperature. A metal pattern or core box is then heated to a temperature of 200 to 300 degrees C. and the damp mixture of sand, thermosetting resin binder and latent curing agent is applied to it by dropping or by fluidization with air. After a period of a few seconds to several minutes, the pattern or box is inverted or opened. The sand, resin and curing agent mix has now sufficiently hardened so that the mold or core can be handled and stored for later use in the metal casting process. The "Warm Box” process operates at somewhat lower temperatures than the "Hot Box” process.
  • Epoxide and epoxide novolac resins cured by dicyandiamide with or without an imidazole are used in the aerospace, automotive, electronic, coating and adhesive industries.
  • the cured epoxies are inert, non-toxic polymers. They are not chemically reactive and remain as very stable compounds. There is no presence of formaldehyde or other toxic materials.
  • a sand, resin, curing agent and accelerator composition comprising a medium to high molecular weight epoxide resin, an epoxide novolac resin, or, a mixture of the two, both having an epoxide equivalent weight of 150 to 250; a latent heat curable curing agent such as dicyandiamide or an imidizole; and possibly an imidazole accelerator.
  • a latent heat curable curing agent such as dicyandiamide or an imidizole
  • imidazole accelerator an imidazole accelerator.
  • a flowable sand, resin, curing agent and accelerator mix it may be necessary to dilute or dissolve the resin, curing agent or accelerator in a solvent such as propylene carbonate, methylglycol, methoxypropanol, methyl lactate or butyl lactate.
  • the resin/diluent solution is applied to the sand at 0.5 to 5.0 percent by weight of the sand.
  • the heat curable latent curing agent and accelerator may be applied to the sand in liquid (with diluent) or powder form at 2.0 to 25.0 percent by weight of the resin.
  • the resulting damp sand mixture is now ready for use by heating it to temperatures in excess of the curing agent and accelerator activation temperature.
  • various accelerators can be used such as modified or unmodified imidazoles, including, but not limited to 2-methyl imidazole, 2-phenyl imidazole and 1-H-imidazole.
  • a sand mixture was prepared having the following composition by weight: 98.2 % Silica Sand AFS Grain Fineness Number 90 1.5 % Liquid Resin - 80 % Dow DER 331 Epoxide Resin 20 % Propylene Carbonate Diluent 0.3 % Powder Curing Agent - 100 % Dicyandiamide
  • the sand mixture was blown into an AFS Standard Tensile Strength Specimen Core Box which had been heated to 150 degrees C.
  • the test core required 2 minutes of curing time after which it had sufficient strength to be removed from the core box. No odor or smoke were present during the curing cycle.
  • the 24 hour tensile strength of the cured sand core was measured as being over 350 pounds per square inch (over 25 Newtons per square centimeter).
  • the mixed sand was stable for over 1 week at room temperature with no loss of performance.
  • a sand mixture was prepared having the following composition by weight: 98.2 % Silica Sand AFS Grain Fineness Number 90 1.5 % Liquid Resin - 40 % Dow DER 331 Epoxide Resin 40 % Dow DER 431 Epoxide Novolac Resin 20 % Propylene Carbonate Diluent 0.3 % Powder Curing Agent - 100 % Dicyandiamide
  • the sand mixture was blown into an AFS Standard Tensile Strength Specimen Core Box which has been heated to 150 degrees C.
  • the test core required 1 minute of curing time after which it had sufficient strength to be removed from the core box. No odor or smoke were present during the curing cycle.
  • the 24 hour tensile strength of the cured sand was measured as being over 350 pounds per square inch (over 25 Newtons per square centimeter).
  • the mixed sand was stable for over 1 week at room temperature with no loss of performance.
  • a sand mixture was prepared having the following composition by weight: 98.3 % Silica Sand AFS Grain Fineness Number 90 1.5 % Liquid Resin - 40 % Dow DER 331 Epoxide Resin 40 % Dow DER 431 Epoxide Novolac Resin 20 % Propylene Carbonate Diluent 0.3 % Powder Curing Agent - 80 % Dicyandiamide 20 % 2-Methyl Imidazole
  • the sand mixture was blown into an AFS Standard Tensile Strength Specimen Core Box which had been heated to 150 degrees C.
  • the test core required only 30 seconds of curing time after which it had sufficient strength to be removed from the core box. No odor or smoke were present during the curing cycle.
  • the 24 hour tensile strength of the cured sand was measured as being over 350 pounds per square inch (over 25 Newtons per square centimeter).
  • the mixed sand was stable for over 8 hours at room temperature with no loss of performance.
  • a sand mixture was prepared having the following composition by weight: 98.475 % Silica Sand AFS Grain Fineness Number 90 1.5 % Liquid Resin - 40 % Dow DER 331 Epoxide Resin 40 % Dow DER 431 Epoxide Novolac Resin 20 % Propylene Carbonate Diluent 0.075 % 1-H-Imidazole
  • the sand mixture was blown into an AFS Standard Tensile Strength Specimen Core Box which had been heated to 150 degrees C.
  • the test core required only 15 seconds of curing time after which it had sufficient strength to be removed fromt he core box. No odor or smoke were present during the curing cycle,
  • the 24 hour tensile strength of the cured sand was measured as being over 350 pounds per square inch (over 25 Newtons per square centimeter).
  • the mixed sand was stable for over 8 hours at room temperature with no loss of performance.

Abstract

A heat curable organic foundry sand binder based upon liquid epoxide or epoxide novolac resin and a latent dicyandiamide or imidazole curing agent, with or without an imidazole accelerator, which may be used as a direct replacement for other "Hot Box" and "Warm Box foundry resin binders.

Description

  • The invention relates to epoxide or epoxide novolac resins mixed with a latent curing agent, with or without an accelerator, cured by heat for the production of foundry sand molds and cores. It is common practice to refer to these heat curable resin binders as "Hot Box" or "Warm Box" binders since the core box or pattern must be heated to affect curing of the sand, resin, curing agent and accelerator mixture.
  • The "Hot Box" and "Warm Box" processes utilize sand coated with a thermosetting resin in liquid form and a latent curing agent in liquid or dry powder form. This mixing of sand, resin and curing agent is done at ambient temperature. A metal pattern or core box is then heated to a temperature of 200 to 300 degrees C. and the damp mixture of sand, thermosetting resin binder and latent curing agent is applied to it by dropping or by fluidization with air. After a period of a few seconds to several minutes, the pattern or box is inverted or opened. The sand, resin and curing agent mix has now sufficiently hardened so that the mold or core can be handled and stored for later use in the metal casting process. The "Warm Box" process operates at somewhat lower temperatures than the "Hot Box" process.
  • This type of process is widely used in the foundry industry to make metal castings of high dimensional tolerance. A disadvantage of the "Hot Box" or "Warm Box" process is that the preferred resins are Phenol/Formaldehyde, Urea/Formaldehyde or Furfuryl Alcohol/Formaldehyde or combinations thereof. Formaldehyde is considered to be a toxic material by nearly all industrial nations. There is also a pungent odor generated during the making of the core or mold as well as during metal pouring and shakeout. The problem of toxic materials and/or obnoxious odor exists with most current "Hot Box" and "Warm Box" processes.
  • It is desireable to have a resin binder system that can be used in a similar manner to the "Hot Box" or "Warm Box" processes without exhibiting obnoxious odors or containing toxic materials such as formaldehyde. It is further desireable that the said new resin binder process have the same physical strengths and performance benefits as the existing "Hot Box" and "Warm Box" resin binders, thereby allowing for the utilization of the new resin process with existing equipment and tooling.
  • Epoxide and epoxide novolac resins cured by dicyandiamide with or without an imidazole are used in the aerospace, automotive, electronic, coating and adhesive industries. The cured epoxies are inert, non-toxic polymers. They are not chemically reactive and remain as very stable compounds. There is no presence of formaldehyde or other toxic materials.
  • It has now been found that a heat curable sand, resin and curing agent mix can be produced utilizing an epoxide or epoxide novolac resin and a latent curing agent with or without an accelerator.
  • According to the present invention, there is provided a sand, resin, curing agent and accelerator composition comprising a medium to high molecular weight epoxide resin, an epoxide novolac resin, or, a mixture of the two, both having an epoxide equivalent weight of 150 to 250; a latent heat curable curing agent such as dicyandiamide or an imidizole; and possibly an imidazole accelerator. Certain imidazoles will affect the curing of epoxides without the presence of dicyandiamide. These mixtures will quickly harden when exposed to heat.
  • Accordingly, to produce a flowable sand, resin, curing agent and accelerator mix, it may be necessary to dilute or dissolve the resin, curing agent or accelerator in a solvent such as propylene carbonate, methylglycol, methoxypropanol, methyl lactate or butyl lactate. The resin/diluent solution is applied to the sand at 0.5 to 5.0 percent by weight of the sand. The heat curable latent curing agent and accelerator may be applied to the sand in liquid (with diluent) or powder form at 2.0 to 25.0 percent by weight of the resin. The resulting damp sand mixture is now ready for use by heating it to temperatures in excess of the curing agent and accelerator activation temperature.
  • In all cases, various accelerators can be used such as modified or unmodified imidazoles, including, but not limited to 2-methyl imidazole, 2-phenyl imidazole and 1-H-imidazole.
  • The following examples will serve to illustrate the invention.
    • EXAMPLE A
  • A sand mixture was prepared having the following composition by weight:
    98.2 % Silica Sand AFS Grain Fineness Number 90
    1.5 % Liquid Resin -
    80 % Dow DER 331 Epoxide Resin
    20 % Propylene Carbonate Diluent
    0.3 % Powder Curing Agent -
    100 % Dicyandiamide
  • The sand mixture was blown into an AFS Standard Tensile Strength Specimen Core Box which had been heated to 150 degrees C. The test core required 2 minutes of curing time after which it had sufficient strength to be removed from the core box. No odor or smoke were present during the curing cycle. The 24 hour tensile strength of the cured sand core was measured as being over 350 pounds per square inch (over 25 Newtons per square centimeter). The mixed sand was stable for over 1 week at room temperature with no loss of performance.
    • EXAMPLE B
  • A sand mixture was prepared having the following composition by weight:
    98.2 % Silica Sand AFS Grain Fineness Number 90
    1.5 % Liquid Resin -
    40 % Dow DER 331 Epoxide Resin
    40 % Dow DER 431 Epoxide Novolac Resin
    20 % Propylene Carbonate Diluent
    0.3 % Powder Curing Agent -
    100 % Dicyandiamide
  • The sand mixture was blown into an AFS Standard Tensile Strength Specimen Core Box which has been heated to 150 degrees C. The test core required 1 minute of curing time after which it had sufficient strength to be removed from the core box. No odor or smoke were present during the curing cycle. The 24 hour tensile strength of the cured sand was measured as being over 350 pounds per square inch (over 25 Newtons per square centimeter). The mixed sand was stable for over 1 week at room temperature with no loss of performance.
    • EXAMPLE C
  • A sand mixture was prepared having the following composition by weight:
    98.3 % Silica Sand AFS Grain Fineness Number 90
    1.5 % Liquid Resin -
    40 % Dow DER 331 Epoxide Resin
    40 % Dow DER 431 Epoxide Novolac Resin
    20 % Propylene Carbonate Diluent
    0.3 % Powder Curing Agent -
    80 % Dicyandiamide
    20 % 2-Methyl Imidazole
  • The sand mixture was blown into an AFS Standard Tensile Strength Specimen Core Box which had been heated to 150 degrees C. The test core required only 30 seconds of curing time after which it had sufficient strength to be removed from the core box. No odor or smoke were present during the curing cycle. The 24 hour tensile strength of the cured sand was measured as being over 350 pounds per square inch (over 25 Newtons per square centimeter). The mixed sand was stable for over 8 hours at room temperature with no loss of performance.
    • EXAMPLE D
  • A sand mixture was prepared having the following composition by weight:
    98.475 % Silica Sand AFS Grain Fineness Number 90
    1.5 % Liquid Resin -
    40 % Dow DER 331 Epoxide Resin
    40 % Dow DER 431 Epoxide Novolac Resin
    20 % Propylene Carbonate Diluent
    0.075 % 1-H-Imidazole
  • The sand mixture was blown into an AFS Standard Tensile Strength Specimen Core Box which had been heated to 150 degrees C. The test core required only 15 seconds of curing time after which it had sufficient strength to be removed fromt he core box. No odor or smoke were present during the curing cycle, The 24 hour tensile strength of the cured sand was measured as being over 350 pounds per square inch (over 25 Newtons per square centimeter). The mixed sand was stable for over 8 hours at room temperature with no loss of performance.

Claims (7)

1. A sand mixture composition consisting of 0.5 to 5.0 % by weight of an epoxide resin having an epoxide equivalent weight of about 150 to 500, particuarly to 250; 0.01 to 1.0 % by weight of a latent heat curable curing agent; and the ballance being a clean dry foundry sand.
2. A sand mixture composition according to Claim 1 wherein the epoxide resin may be an epoxide novolac resin or a blend of epoxide resin and epoxide novolac resin.
3. A sand mixture composition according to Claim 2 wherein the epoxide resin and/or epoxide novolac resin may be diluted with a solvent such as propylene carbonate.
4. A sand mixture composition according to Claim 3 wherein the latent heat curable curing agent is Dicyandiamide.
5. A sand mixture composition according to Claim 4 wherein the latent heat curable curing agent may be accelerated by an Imidazole such as 2-Methyl Imidazole, 2-Phenyl Imidazole or 1-H-Imidazole.
6. A sand mixture composition according to claim 3 wherein the latent heat curable curing agent is an Imidazole such as 1-H-Imidazole.
7. A method of making bonded sand foundry cores or molds utilizing the sand mixture compositions according to Claims 1 through 6.
EP19900119969 1989-10-20 1990-10-18 Novel heat curable organic resin foundry sand binder process Withdrawn EP0423780A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3934940 1989-10-20
DE19893934940 DE3934940A1 (en) 1989-10-20 1989-10-20 BINDING AGENT TO SET FOUNDRY SAND

Publications (2)

Publication Number Publication Date
EP0423780A2 true EP0423780A2 (en) 1991-04-24
EP0423780A3 EP0423780A3 (en) 1992-10-28

Family

ID=6391823

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900119969 Withdrawn EP0423780A3 (en) 1989-10-20 1990-10-18 Novel heat curable organic resin foundry sand binder process

Country Status (2)

Country Link
EP (1) EP0423780A3 (en)
DE (1) DE3934940A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001021687A1 (en) * 1999-09-23 2001-03-29 The Dow Chemical Company Solvent composition
WO2021037313A1 (en) 2019-08-30 2021-03-04 Bindur Gmbh Method for producing cores and molds in sand casting
WO2021037312A1 (en) 2019-08-30 2021-03-04 Bindur Gmbh Hot-curing mould material for producing cores and moulds in the sand casting process

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3305527A (en) * 1964-12-09 1967-02-21 Celanese Coatings Company Inc Epoxide resin compositions
US3705872A (en) * 1971-04-05 1972-12-12 Shell Oil Co Process for the production of bonded particles as a material of construction
JPS6072636A (en) * 1983-09-28 1985-04-24 Nissan Motor Co Ltd Composition for binding casting mold
DE3433851A1 (en) * 1984-09-14 1986-03-27 Gurit-Essex, Freienbach CHEMICALLY CURABLE RESINS FROM COMPOUNDS CONTAINING 1-OXA-3-AZA-TETRALINE GROUPS AND CYCLOALIPHATIC EPOXY RESINS, METHOD FOR THE PRODUCTION AND CURING THEREOF AND THE USE OF SUCH RESINS

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3305527A (en) * 1964-12-09 1967-02-21 Celanese Coatings Company Inc Epoxide resin compositions
US3705872A (en) * 1971-04-05 1972-12-12 Shell Oil Co Process for the production of bonded particles as a material of construction
JPS6072636A (en) * 1983-09-28 1985-04-24 Nissan Motor Co Ltd Composition for binding casting mold
DE3433851A1 (en) * 1984-09-14 1986-03-27 Gurit-Essex, Freienbach CHEMICALLY CURABLE RESINS FROM COMPOUNDS CONTAINING 1-OXA-3-AZA-TETRALINE GROUPS AND CYCLOALIPHATIC EPOXY RESINS, METHOD FOR THE PRODUCTION AND CURING THEREOF AND THE USE OF SUCH RESINS

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
KROSCHWITZ ET AL 'Encyclopedia of Polymer Science and Engineering, Volume 6' 1986 , WILEY-INTERSCIENCE , NEW YORK, USA *
WPIL DATABASE, Derwent Publications Ltd., London GB AN=85-137709 [23] DW=8523 & JP-60/72636 ( NISSAN MOTOR KK) 24 April 1985 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001021687A1 (en) * 1999-09-23 2001-03-29 The Dow Chemical Company Solvent composition
WO2021037313A1 (en) 2019-08-30 2021-03-04 Bindur Gmbh Method for producing cores and molds in sand casting
WO2021037312A1 (en) 2019-08-30 2021-03-04 Bindur Gmbh Hot-curing mould material for producing cores and moulds in the sand casting process

Also Published As

Publication number Publication date
DE3934940A1 (en) 1991-04-25
EP0423780A3 (en) 1992-10-28

Similar Documents

Publication Publication Date Title
US4216133A (en) Shell process foundry resin compositions
US3024215A (en) Foundry composition containing furfuryl alcohol polymer, foundry structure thereof, and method of making same
WO2002042349A2 (en) Hardener for epoxy of polyols and n-containing hardener
DE102016123051A1 (en) Amino acid-containing molding material mixture for the production of moldings for the foundry industry
US4317763A (en) Catalysts and binder systems for manufacturing sand shapes
US5607986A (en) Heat cured foundry mixes and their use
JP2009537328A (en) Composition and application method for removal of hexamethylenetetramine in shell sand encapsulation
US4143022A (en) Foundry resin compositions comprising furfuryl alcohol and a copolymer of styrene and allyl alcohol
EP0423780A2 (en) Novel heat curable organic resin foundry sand binder process
US3838095A (en) Foundry sand coated with a binder containing novolac resin and urea compound
JP5595539B2 (en) Method for removing odor in shell sand
US4766949A (en) Hot box process for preparing foundry shapes
RU2305019C2 (en) Cold-box process binder containing epoxy resin, acrylate and alkyl esters
US3046147A (en) Water soluble mold and core binders and method
US5275648A (en) Heat curable organic resin foundry sand binder composition
US3268466A (en) Cold-hardening foundry mixture comprising an epoxy resin and furfuryl alcohol as a catalyst
JPS5823177B2 (en) Mold binder consisting of furfuryl alcohol and aromatic dialdehyde
EP1572397B1 (en) Cold-box foundry binder systems having improved shakeout
EP0398463B1 (en) Ester hardeners for phenolic resin binder systems
US4478269A (en) Furan Resin coated aggregate
US3118850A (en) Self-settable sand-phenolic resin composition containing 2, 5-dimethylpiperazine andmolded article made therefrom
JPH09234540A (en) Binder coated sand grain for mold
US4366267A (en) Catalysts and binder systems for manufacturing sand shapes
JPH02137639A (en) Binder for casting mold
US5703144A (en) Solid furan binders for composite articles

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): CH DE FR GB IT LI NL SE

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): CH DE FR GB IT LI NL SE

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19930419