JPS6340443B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to new and useful curable epoxy resin compositions comprising a curable epoxy resin and a small amount of an oxidizing agent capable of reacting with sulfur dioxide to form a catalyst and cure the epoxy resin. The curable epoxy resin composition is particularly useful for producing molded fillers comprising epoxy resin and inorganic solid particles. Particularly useful fillers of this type include abrasive articles, foundry cores and molds. Over the past few decades, so-called "epoxy" resins have gained wide acceptance in various fields. Epoxy resins have very good electrical, thermal and chemical properties and exhibit low shrinkage during curing. Epoxy resins exhibit good adhesion to the surfaces of a variety of materials, making them particularly useful as coatings, electronic and electrical applications, and binders and adhesives in many applications. Epoxy resin has an epoxy group in it, i.e. It is characterized by the presence of an epoxy group represented by the formula (in which x represents a small integer). Such resins are commercially available from a variety of sources. The products available on the market are characterized by a wide variety of properties, depending on the chemical composition of the epoxy resin. Epoxy resins are converted into useful forms by condensation reactions. Note that this condensation reaction is initiated and/or promoted by heat and/or a condensation catalyst or a curing agent. Typically, epoxy resins are commercially available in the form of liquid or solid compositions containing partially condensed resins, which may or may not contain curing agents. If a catalyst is present, final curing to a usable solid form is accomplished by heating the composition to a suitably high temperature at the time of use. Commercially available epoxy resin compositions often do not contain curing agents or curing catalysts.
The reason for this is that many curing agents have some degree of activity at ambient temperatures, resulting in such compositions having an undesirably short shelf life. Manufacturers of epoxy resins therefore sell curing agents in containers for use with the epoxy resins, and typically include such curing agents when it is desired to cure the resin into a usable solid form. Or a curing catalyst is added to the epoxy resin. Other methods of curing epoxy resins are described in the literature, particularly at ambient temperatures and without incorporating curing agents into the composition. For example, US Patent No.
No. 3,139,657 describes that epoxy resin compositions are usually cured by using gaseous curing agents. Examples of such curing agents include some inorganic nitrogen, and halogen compounds such as hydrogen halides, boron-halogen compounds,
There are silica-halogen compounds and nitrogen-halogen compounds. However, since the epoxy resin composition comes into contact with the solid heat absorber and the gas hardening agent during treatment with the gas hardening agent, it is essential that the exposed surface be in the form of a thin film. Therefore, the above specification states that such a film has a diameter of approximately 0.254 mm (0.01 mm).
It is stated that if the thickness is thicker than 1 inch), sufficient curing cannot be achieved by this treatment. In the foundry industry, sand is coated with a resin binder and shaped into molds and cores for producing precision castings. A wide variety of techniques have been developed for the manufacture of sand cores and molds. These include hot boxes for forming molds and cores.
box) method; Ciel method: “No-bake” (No-
Bake), and cold box
There is a law. In the hot box method and the shell method,
Sand molds and cores are formed by heating a mixture of sand and thermosetting resin at a temperature of approximately 150 to 320°C in contact with a pattern that yields the desired shape for the mold or core. be done. The resin polymerizes and a core or mold is formed. This type of method is described in US Pat. No. 3,059,297 by Deyun et al.
No. 3,020,609 to Brown et al. A particular disadvantage of the hot box and shell processes is that they require heating the master box to 150 DEG -320 DEG C. in order to polymerize and harden the resin binder. This is a very expensive and generally expensive technique. Cold box methods for forming cores and molds involve the use of sand in which the sand is mixed with or coated with a resin that can be cured at room temperature by acid or base catalysts. Acid or base catalysts are used in liquid, fixed or gaseous form. Typical cold boxing methods are U.S. Pat.
3108340, U.S. Patent No. 3184814 to Brown et al.
No. 3639654, Australian Patent No. 453160 and British Patent No. 3639654 to Robbins.
It is disclosed in the specification of No. 1225984. Many of these methods involve the use of sulfur-containing acid catalysts, such as benzenesulfonic acid, toluenesulfonic acid, and the like. Several years ago, a method for the room temperature polymerization of condensation resins was developed in which the acid curing agent is generated in situ in the resin or in the sand-resin mixture. Previously, U.S. Pat.
No. 3,145,438 it was proposed to inject SO ₃ in gaseous form into a mixture of sand and resin and to cure the resin at room temperature. But with this method SO ₃
It was found that the resin in the treated areas immediately hardened, thereby inhibiting the diffusion of the SO ₃ gas to other parts of the resin, especially to the center of the mixture. Subsequently, methods have been developed that circumvent this difficulty. Richard U.S. Pat. No. 3,879,339 discloses that sand is coated with a suitable oxidizing agent, such as an organic peroxide, and then coated with a resin to be used to bond the sand into a core or mold shape. After that, the sand-resin mixture is molded into a suitable shape and gas
It is stated that it should be treated with SO ₂ . This SO ₂
is oxidized in the system to SO ₃ and converted to sulfur-containing molecules by the water present in the mixture. The sulfur content produced in the system polymerizes the resin quickly and uniformly at room temperature. This process has proven to be industrially successful and has been used to treat phenolic, furan and urea resins.
Applied to formaldehyde resins, as well as mixtures and copolymers thereof. The cold box process described in Richard U.S. Pat. No. 3,879,339 uses a wide variety of peroxides that can be added to the sand along with the resin used to form the sand core or mold. It has been introduced. This combination is formed into a molded body and treated with SO ₂ gas. Most of the peroxides described in the '339 patent are extremely expensive and often difficult to handle.
Difficult to transport or transport. Special licenses are required for interstate trade of organic peroxides. Organic peroxides are often highly flammable or otherwise present a fire hazard. Also, organic peroxides are often sensitive to shock and may explode under certain conditions. As a result, from economic and safety considerations, there are no organic peroxides that can be used in the method described in the above-mentioned US Pat. No. 3,879,339. Although the prior art has shown some applications of epoxy resins in the manufacture of foundry cores and molds, such resins usually require the use of strongly acidic gases for curing, and this If serious problems arise, such as equipment corrosion,
Makes it difficult to use epoxy bonding products. US Pat. No. 3,145,438 to Kottoke et al. discloses a gas curing process for curing sand and abrasive bonding, sand cores and mold resins. Such resins are primarily furfuryl alcohol formaldehyde resins, and some epoxy resins including epoxidized linseed oil, mono- and di-vinyl cyclohexane dioxide, butadiene dioxide, glycidyl metharylate, and polymers thereof. Curing gases are strong acid gases, including boron trifluoride, boron trichloride, hydrogen chloride, and sulfur trioxide. US Pat. No. 3,107,403 to Moore states:
A method of making sand cores or molds is disclosed that uses an epoxy resin that is cured by treating the molding composition with a strong Lewis acid such as boron trifluoride, titanium tetrachloride, tin tetrachloride, and the like. U.S. Pat. No. 3,428,110 to Walker et al. discloses a method for making sand cores and molds using a curable resin, such as a phenolic resin, and a polyisocyanate that is cured by treatment with a gaseous amine. ing. U.S. Pat. No. 3,519,056 by Bykerdyk et al. discloses a method for manufacturing a mold for metal casting, in which the mold is molded from inorganic fibers and is made of a thermosetting resin containing an epoxy resin or a phenolic resin. The resin is cured at high temperature. U.S. Pat. No. 4,176,114 to Stewart et al. discloses a method for making foundry cores and molds using resins modified with polyfurfuryl alcohol, in which sand is mixed with resin and organic It is treated with peroxide or hydroperoxide and then subjected to sulfur dioxide gas treatment. US Pat. No. 4,050,500 to Steinbaker discloses a shell molding process that uses soluble silicates, such as sodium silicate, as the binder. This sodium silicate is used to bind sand in addition to thermoset organic resins, which resins are benzoyl peroxide or t-
Hardened by treatment with peroxides such as butyl perbenzoate. GB 2,066,714 discloses a method for producing molded cast articles using a binder containing ethylenically unsaturated monomers and curing with a free radical initiator. The initiator includes an organic peroxide and a catalyst such as sulfur diacid. Illustrative monomers and polymers thereof that have been described as useful include acrylates and modified acrylate copolymers such as epoxy acrylates, polyether acrylates, polyester-acrylates and polyester-urethane-acrylates. Also, U.S. Pat. No. 3,139,657 to Murray discloses a method of curing epoxy resins with gaseous curing agents. This includes many gaseous curing agents, namely fluorine, chlorine and bromine; hydrogen fluoride;
Hydrogen chloride, hydrogen bromide and hydrogen iodide; boron trichloride, boron trifluoride, boron monochloride pentahydride, boron monobromide pentahydride; silicone fluoride, trifluorosilicane and chlorosilicane;
Bromine chloride, chloroazide, nitrosyl chloride, nitrosyl fluoride, nitrosyl bromide, nitrile chloride and nitrile fluoride; nitrogen dioxide and nitrogen tetroxide are listed. SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel and useful curable epoxy resin comprising a mixture of acid-curable epoxy resins and a small amount of an oxidizing agent capable of reacting with sulfur dioxide to form a catalyst and cure the epoxy resins. An object of the present invention is to provide an epoxy resin composition. It is an object of the present invention to provide a superior sand-resin-peroxide composition having an extremely good pot life for sand cores and molds. The curable epoxy resins of the present invention have been found to be particularly useful in forming foundry cores and molds, such as sand cores or molds. These and other objects of the invention are achieved by a foundry core and mold made from sand and an epoxy resin binder by a superior gas curing process. Epoxy monomers alone or with the addition of thermosetting condensation resins are mixed with foundry blade sand together with organic peroxides, hydroperoxides or hydroxy-hydroperoxides, or mixtures thereof with hydrogen peroxide. The sand is then formed into a core or mold and gassed with sulfur dioxide for a few seconds. The cores or molds obtained after a few seconds of gas treatment at temperatures between room temperature and 150°C (300°C) are superior to cores and molds in castings made with other resins under similar conditions. It has far superior strength and hardness to conventional casting applications. Moreover, the sand-resin-peroxide mixture is a sand molding composition with an unexpectedly excellent pot life. Description of preferred embodiments The composition of the present invention comprises an acid-curable epoxy resin;
A curable epoxy resin composition comprising a mixture of sulfur dioxide and a small amount of an oxidizing agent capable of reacting with sulfur dioxide to form a catalyst to cure the epoxy resin. The epoxy resin used in the present invention is acid-curable and contains an epoxy group, i.e. It can be any one of a number of well-known resins characterized by the presence of an epoxy group represented by the formula (where x represents 0 or a small integer). Such resins are a mixture of aliphatic and aromatic. Generally, aliphatic-aromatic mixed epoxy resins are bis-(hydroxy-aromatic) alkanes or tetrakis-(hydroxy-aromatic) alkanes.
aromatic) alkanes with halogen-substituted aliphatic epoxides in the presence of a base such as sodium hydroxide or potassium hydroxide. Examples of halogen-substituted aliphatic epoxides include epichlorohydrin, 4-
Chloro-1,2-epoxybutane, 5-bromo-
1,2-epoxypentane, 6-chloro-1,3
- Epoxyhexane, etc. It is generally preferred to use chlorine-substituted aliphatic epoxides in which the epoxy group is at the end of the alkyl chain. The most widely used epoxy resin is the diglycidyl ether of bisphenol A. These are produced by reacting epichlorohydrin with bisphenol A in the presence of an alkaline catalyst. By adjusting the operating conditions and varying the ratio of epichlorohydrin to bisphenol A, products with different molecular weights can be obtained. Other useful epoxy resins include other bisphenol compounds such as bisphenol B, F, G
and H diglycidyl ethers. Epoxy resins of the above type based on various bisphenols are very widely available on the market. The product name of this group is "Epon"
(Epon) resin is known, and the resin is
Manufactured by a chemical company. For example, "Epon 820" is an epoxy resin with an average molecular weight of about 380 and is made from 2,2-bis-(p-hydroxyphenol)propane and epichlorohydrin. Similarly, "Epon 1031" is approximately
It is an epoxy resin with an average molecular weight of 616,
Produced from epichlorohydrin and symmetrical tetrakis-(p-hydroxyphenol)ethane.
"Epon 828" has a molecular weight of 350-400 and a molecular weight of about 175-
It has an epoxy equivalent weight of 210. Another group of epoxy resins available on the market is known under the trade name EPI-REZ (Celanese Resin, Division of Celanese Coatings Company). For example, EPI-REZ510 and
EPI-REZ509 is a commercial grade of bisphenol A or diglycidyl ether with slightly different viscosities and epoxy equivalents. Another group of epoxy resins useful in this invention are novolaks, particularly epoxy cresol and epoxy phenol novolaks. These are prepared by reacting novolak resins, usually produced by the reaction of orthocresols or phenols with formaldehyde, with epichlorohydrin. Also, epoxy resins derived from non-benzenoid materials, such as aliphatic or cycloaliphatic hydroxyl-containing compounds, can be used in the present invention.
Epoxy resins with non-benzenoid molecular structures are commonly referred to in the art as aliphatic epoxy resins or cycloaliphatic epoxy resins. Cycloaliphatic epoxy resins are prepared by peracetic epoxidation of cyclic olefins and by condensation of an acid such as tetrahydrophthalic acid with epichlorohydrin followed by dehydrohalogenation. can be manufactured.
Aliphatic epoxy resins can be produced by reaction with hydroxyl group-containing aliphatic compounds, such as aliphatic diols and triols, and cyclic compounds. For example, ethylene glycol or glycerol can be reacted with halogen-substituted aliphatic epoxides, such as epichlorohydrin (and others mentioned above), which are characterized by lower viscosities than epoxy resins derived from aromatic hydroxy compounds. A liquid epoxy resin can be produced. Such aliphatic epoxy resins, when cured, are less brittle than aromatic epoxy resins and exhibit elastomeric properties in many instances. Aliphatic epoxy resins are widely available on the market, such as those sold by Shell Chemical Company and Reichhold Chemicals. To specifically illustrate, 140
There is Epon 562, which has an epoxy equivalent weight of ~165 and a hydroxyl equivalent weight of about 65. In the present invention, an oxidizing agent is incorporated into the acid-curable epoxy resin formulation as a curing agent. The oxidizing agent mixed into the acid-curable epoxy resin composition of the present invention is
A catalyst is formed that reacts with sulfur dioxide to cure the epoxy resin. Many oxidizing agents are suitable for use in the epoxy resins of the present invention. Suitable oxidizing agents include peroxide hydroperoxides, hydroxy hydroperoxides, chlorates, perchlorates, zincates, hydrochlorides, perbenzoates, permanganates, and the like. However, the oxidizing agent is preferably a peroxide, a hydroperoxide or a mixture of peroxides or hydroperoxides and hydrogen peroxide. Organic peroxides can be aromatic or alkyl peroxides. Examples of useful diacyl peroxides include benzoyl peroxide, lauroyl peroxide, and decanoyl peroxide. Ketone peroxides are particularly useful and include methyl ethyl ketone peroxide, isobutyl methyl ketone peroxide and 2,4-pentanedione peroxide.
Examples of peroxyester oxidizing agents include t-butyl peroctoate,
These include t-butyl peracetate, t-butyl perbenzoate and t-amyl peroctoate. Examples of alkyl peroxides include dicumyl peroxide and di-t-butyl peroxide. Examples of hydroperoxides useful in the present invention include t-butyl hydroperoxide, cumene hydroperoxide, and paramenthane hydroperoxide. One or a mixture of two or more of the organic peroxides or hydroperoxides mentioned above can be used together with hydrogen peroxide as a curing agent or accelerator. The composition of the present invention comprises about 10 to about 50% by weight based on the weight of the epoxy resin,
Preferably it contains about 15 to about 45 weight percent oxidizing agent. It has been discovered that the acid-curable epoxy resins of the present invention comprising mixtures of epoxy resins and oxidizing agents such as peroxides can be cured by treating the mixtures with gaseous sulfur dioxide. Such curing begins almost instantaneously and yields a resin with good strength and surface hardness ready for use. This result is surprising. The reason for this is that the curing of such epoxy resins is not described in any literature. Generally, the epoxy resin-peroxide mixture is heated between ambient temperature and about 150°C.
Contact with sulfur dioxide for an instant to about 5 minutes at a temperature of °C. In some cases, sulfur dioxide can be entrained in the carrier gas stream in known manner. Examples of carrier gases commonly used for this purpose include air and nitrogen. Epoxy resin-
The amount of sulfur dioxide required to cure the peroxide mixture is a catalytic amount, and generally an amount of sulfur dioxide on the order of about 0.5% by weight of the carrier gas is sufficient to cause polymerization and cure. However, as mentioned above, it is also possible to contact the epoxy resin-peroxide mixture directly with sulfur dioxide in the presence of an optional carrier gas. The acid-curable epoxy resins of this invention can be modified by adding various monomers and polymers that produce desired properties in the cured epoxy system. For example, the thermal stability of epoxy systems can be increased by mixing various monomers with the epoxy resin-oxidizer mixture. In this case, such mixtures can be cured with sulfur dioxide as described above. Examples of monomeric or polymeric materials that can be mixed with the acid-curable epoxy resin of the present invention include:
Thermosetting resins based on acrylic or vinyl monomers, furfuryl alcohol, polyfurfuryl alcohol, formaldehyde, urethane resins,
or a mixture of these. The exact mechanism by which these identified monomers and polymers modify the properties of acid-curable epoxy resins is not known at this time. It has been discovered that up to about 50% by weight of the monomers and polymers specified above can be mixed with an epoxy resin to form a modified epoxy resin system according to the present invention. Acrylic compounds are particularly useful as modifiers for epoxy systems, and specific examples include trimethylolpropane triacrylate and furfuryl methacrylate. Examples of formaldehyde-based thermosetting resins that are useful as modifiers include phenol-formaldehyde resins or urea-formaldehyde resins. Resorcinol is also particularly useful as a modifier. In a preferred embodiment of the present invention, (a) a large amount of solid particulate material, (b) a small amount of (a) acid-curable epoxy resin, and (b) sulfur dioxide are reacted to form a catalyst and the epoxy resin is A curable epoxy resin composition is produced that includes a mixture with an oxidizing agent that can be cured. Generally, such curable epoxy resin compositions contain from about 0.2% to about 15%, preferably from about 0.8% to about 1.0%, of epoxy resin based on the weight of the particulate material, with an oxidizing agent based on the weight of the epoxy resin. about 10 to about 50% by weight, preferably about 15 to about 40%
Contains % by weight. As mentioned above, the acid-curable epoxy resin used in this composition is a thermosetting resin based on acrylic or vinyl monomers, furfuryl alcohol, polyfurfuryl alcohol, resorcinol, formaldehyde, or urethane resins. The mixture can be a modified epoxy resin containing up to about 50% by weight. The results obtained are surprising. The reason for this is that epoxy resins have not traditionally been cured in this manner and have not been cured using strong sulfur-containing acids, which are thought to be produced by the reaction of sulfur dioxide and peroxide. A somewhat similar process is covered by U.S. Patent No.
No. 3,879,339, in which urea-formaldehyde, furan, or phenolic resole resins cured by acid-catalyzed condensation reactions are gassed with sulfur dioxide in the presence of organic peroxides or hydroperoxides. It is disclosed that it can be cured by.
This process is registered trademark Insta in North America.
Sold at Draw. The US patent only discloses the production of foundry cores and molds with condensation curable resins, such as furfuryl alcohol polymers and copolymers, and phenolic resins. Epoxy resins are not cured by condensation reactions and are therefore not equivalent to condensation resins. A variety of solid particulate materials can be used in the epoxy resin composition of the present invention. The choice of particulate material is determined in part by the intended use of the filled epoxy resin. Particulate materials that can be used as fillers in the compositions of the invention include all materials containing a high proportion of silica, such as silica sand, water-resistant materials, particulate metal oxides, such as zirconium oxide,
and abrasives such as carborundum, emery, quartz, garnet, aluminum oxide, silicon carbide, etc. Other materials can be included in the compositions of the present invention to achieve other desired results. For example, the material may include a coupling agent to improve the bond between the epoxy resin and the particulate material, and the coupling agent may include a coupling agent in the polymeric material that regains its original properties after a long period of time and/or after exposure to moisture. improve the ability of Examples of coupling agents known in the art include silanes and titanates. Coupling agents are chemically hybrid materials having the functionality of an organic reactive group at one end of the molecule and the functionality of an inorganic alkoxysilane or alkoxytitanate at the other end. Typical organic functional groups found in silanes include vinyl groups, chloroalkyl groups, epoxy groups, methacrylate groups, amine groups and styrylamine groups. Silane coupling agents known in the art are particularly useful in the compositions of the present invention filled with solid particulate materials. A mixture comprising solid particulate material, epoxy resin, oxidizing agent and other optional additives, such as silane, can be molded into various shapes using molds. While the mixture is in the mold, it is treated with sulfur dioxide gas as described above to effect almost instantaneous curing. The articles thus obtained have good strength and surface hardness ready for use. The introduction of gas into the shaped composition can be carried out by known processes in various ways depending on the core or mold to be manufactured. For example, in the case of a core, the composition is molded in a mold having an orifice communicating with the outside and equipped with a filter, through which gas is introduced into the composition under pressure. When manufacturing molds from the composition,
A reverse procedure is followed in which the sand and resin mixture is clamped into a master mold and the gas is introduced through grooves machined into the master mold. After manually, mechanically, hydraulically or pneumatically clamping the composition of granular filler, epoxy resin and oxidizing agent, the gas is injected at a pressure and at an ambient temperature that can be determined and varied by the dimensions of the object to be produced. be able to. This pressure is
There must be enough gas to distribute uniformly over the entire volume of the composition and to escape out of the mold. The pressure commonly used is about 0.3 to 5 atmospheres. The molded articles produced in this way exhibit good strength and surface hardness and are ready for use. Thus, this method allows foundry cores and molds to be easily manufactured and provides several advantages over methods using condensation type curable resins. One important advantage is the absence of formaldehyde in the system. The reason for this is that most condensation resins, such as phenol, urea-formaldehyde, furfuryl alcohol-formaldehyde, etc. liberate formaldehyde during curing. Epoxy resins do not liberate significant formaldehyde during curing. The thermal stability of epoxy systems can be increased by the addition of furfuryl alcohol, furfuryl alcohol-formaldehyde polymers or phenol formaldehyde resins or precursors. Another important advantage of the compositions of the invention is the reduced amount of water present in the system. Commonly used epoxy formulations contain less than 1% water compared to 2-8% in conventional sulfur dioxide cured furans. Furthermore, little or no water is liberated during the curing reaction, which is the ring opening and crosslinking reaction. On the other hand, furan, phenolic and urea formaldehyde resins liberate significant amounts of water upon curing. In some foundry applications, such as pouring high quality steel castings, water can contribute to casting defects known as "pinholes." Another advantage of the epoxy resin compositions of the present invention is reduced surface migration of reaction by-products. Methods using condensation resins tend to cure more slowly near the surface of the mold due to absorption of the heat of reaction, possibly causing reaction by-products to migrate toward the mold surface. If the temperature of the box is lower than the ambient temperature, this creates a problem in that a high concentration of peroxide is required to produce an article with a sufficiently hard surface. Such effects do not appear in epoxy resin systems, and excellent core strength can be obtained even if the amount of peroxide is deliberately reduced. Yet another advantage is high acid consumption (high acid consumption).
Superior performance and excellent pot life have been observed in lakeside applications (demand). For example, furan resins perform well in low acid consumption silica sands, but the high acid consumption Lakeside basicity slows curing and requires high amounts of resin and peroxide. This significantly increases the cost of the system and the amount of organic material in the sand. The epoxy system of the present invention can be applied extremely well to each of the above-mentioned sands, and in the case of Manley 1-L lakeside, which is a common lakeside widely used in foundry applications, Uedron ( more than required for extremely low acid consumption silicas such as Wedron) 5040.
No need to increase resin or peracid. The length of time during which a sand-resin-peroxide mixture is stored, exposed to the atmosphere, and treated with sulfur dioxide to still yield an acceptable product is called the pot life. The pot life for the resin is 12-16 hours, depending on the temperature of the sand. In the case of the epoxy system according to the invention, a pot life of 6 days was observed. Under favorable conditions and with clean silica sand, the pot life of furan resin is 3 days. With similar sands, the epoxy resin system of the present invention was observed to have a pot life of over 10 days. Yet another advantage obtained when using the epoxy resin system of the present invention is the significant cost savings, especially in high acid consuming sands where less resin is required. Depending on the type of sand, furan resins require 40-50% peroxide, while epoxy resins have an average peroxide content of 30%. Epoxy processing works well with low cost cumene hydroperoxide catalysts. Since epoxy systems require less peroxide, the amount of sulfur dioxide required for catalysis is even smaller. Next, the present invention will be explained based on examples. Example 1 A mixture of 100 parts of Epon 828 resin, bisphenol-type A epoxy resin and 30 parts of cumene hydroperoxide was milled for about 5 minutes. This mixture was used in the form of a film and gassed with sulfur dioxide for about 0.5 seconds at ambient temperature. The initial curing of the resin resulted in a slightly flexible epoxy film. Example 2 Core bonded with epoxy resin In this test, Uedron 5040 sand was mixed with 1.0% by weight (based on sand) Epon 828 resin,
Pulverized for minutes. Epon 828 is a bisphenol A type epoxy resin. 30% by weight (based on resin weight) of cumene hydroperoxide was added to the mixture and the resulting mixture was milled for an additional 3 minutes. This sand-resin-peroxide mixture was then used in a mold [standard dogbone molding test mold].
The specimen was pressed or poured into a shaped specimen mold and gassed with sulfur dioxide for approximately 0.5 seconds at room temperature, followed by air purging for 15 seconds. Gas treatment time of about 0.3 seconds to about 5 minutes and room temperature to about
Temperatures of 150°C (300°C) could be used. Epoxy resins are characterized by being tough and slightly flexible during initial curing. Flexibility is beneficial in many applications and reduces core breakage when removing the article from the mold. However, in some cases, a hard initial cure is preferred to prevent deformation of thin, intricate designs. 5-15% epoxy resin
Modification with a phenol-formaldehyde resin resulted in a harder initial cure and higher initial tensile strength. The product obtained after 20 seconds (test molding) could be used immediately as described above. This product had hardness and tensile strength equal to or better than similar products made using condensate resins. Furthermore, this method could be similarly carried out using bisphenol-F type epoxy resin and epoxy novolak resin. Example 3 Core Bonded with Modified Epoxy Resin In another implementation, Uedron 5040 sand, 15%
modified with furfuryl alcohol (or furfuryl alcohol-formaldehyde polymer)
1.0% by weight (based on sand) of Epon 828 was mixed and the resulting mixture was milled for 3 minutes. Furthermore, Epon 828
is a bisphenol-A type epoxy resin. To this mixture was added 30% by weight (based on the resin weight) of cumene hydroperoxide and the mixture was
Pulverized for minutes. The sand-resin-peroxide mixture was then pressed or poured into a mold (standard dogbone mold test mold) and gassed with sulfur dioxide for approximately 0.5 seconds at room temperature, followed by air purge for 15 seconds. Gas treatment times of about 0.3 seconds to about 5 minutes and temperatures of room temperature to about 150°C could be used. The product obtained after 20 seconds was ready for use as described above. This product had hardness and tensile strength equal to or better than similar products made using the condensed form of the resin. This procedure could be similarly carried out using bisphenol-F type epoxy resins and epoxy novolac resins. Example 4 Baking of Epoxy Resin Bonded Cores The test bodies produced in Examples 2 and 3 were baked in a Matsufuru furnace at approximately 990°C (1800°C). After 2 minutes had elapsed, the biscuit (test molded product) was taken out and hit with a small hammer to measure the ease of breaking. The furfuryl alcohol (or furfuryl alcohol-formaldehyde) composition was extremely hard. These tests showed that the increased thermal stability was due to modification of the epoxy with furfuryl alcohol or furfuryl alcohol formaldehyde resin. Example 5 Uedron 5040 sand was modified with 15% furfuryl alcohol to produce 1.0% by weight (based on sand) Epon.
828 resin and milled for 3 minutes. To this mixture was added 30% by weight (based on the resin weight) of cumene hydroperoxide and the resulting mixture was milled for an additional 3 minutes. The sand-resin-peroxide mixture was then pressed or poured into a mold (standard dogbone mold test mold) and gassed with sulfur dioxide for approximately 0.5 seconds at room temperature, followed by air purge for 15 seconds. about
Gas treatment time from 0.3 seconds to about 5 minutes and from room temperature to about 150℃
Temperatures in °C could be used. The test moldings, ie biscuits, were then heated for a further 5 minutes at approximately 110°C. After cooling to room temperature, the biscuits are comparable to 20.39 Kg/cm ² (290 psi) without baking.
It had a tensile strength of 35.15 Kg/cm ² (575 psi). This procedure could be similarly carried out using bisphenol-F type epoxy resins and epoxy novolac resins. Example 6 Core Bonded with Modified Epoxy Resin Uedron 5040 sand was mixed with 1.0% by weight (based on sand) of Modified Epon 828 and ground for 3 minutes. 80%
Epon 828, 10% phenolic resin, 0.2% A
-187 silane, containing 10% methanol, plus 20
% trimethylolpropane triacrylate was used. The phenolic resin used in this example and the following examples was prepared by mixing formaldehyde and phenol under basic conditions at a ratio of 1.5:
It is a resol reacted at a ratio of 1:1. 30% by weight (relative to resin weight) of cumene hydroperoxide was then added to the mixture and the resulting mixture was milled for an additional 3 minutes. The sand-resin-peroxide mixture was then pressed or poured into a mold (standard dogbone mold test mold) and gassed with sulfur dioxide for approximately 0.5 seconds at room temperature, followed by air purge for 20 seconds. Gas treatment times from about 0.3 seconds to about 5 minutes and temperatures from room temperature to about 150°C (300°C) could be used. After about 20 seconds the product was ready for use as described above. This product had an instantaneous tensile strength (after 20 seconds) of 10.968 Kg/cm ² (156 psi), compared to 9.140 Kg/cm ² (130 psi) for the unmodified product. This product had hardness and tensile strength equal to or better than similar products made using condensate resins. This procedure could be similarly carried out using bisphenol-F type epoxy resins and epoxy novolac resins. Example 7 Core bonded with modified epoxy resin Uedron 5040 sand, 1.0% by weight (based on sand)
of modified Epon 828 and ground for 3 minutes. The composition used contained 80% Epon 828, 10% phenolic resin, 0.2% A-187 silane, 10% methanol, to which was added 20% furfuryl methacrylate. 30% by weight in this mixture
of cumene hydroperoxide (based on resin weight) was added and the resulting mixture was milled for an additional 3 minutes. The sand-resin-peroxide was then pressed or poured into a mold (standard dogbone mold test mold) and gassed with sulfur dioxide for approximately 0.5 seconds at room temperature. Gas treatment times from about 0.3 seconds to about 5 minutes and temperatures from room temperature to about 150°C (300°C) could be used. The product obtained after 20 seconds was ready for use as described above. This product had a significantly greater instantaneous tensile strength than the unmodified product. The product also had hardness and tensile strength equal to or better than similar products made using condensate resins. This procedure could be similarly carried out using bisphenol-F type epoxy resins and epoxy novolac resins. Example 8 Core bonded using modified epoxy resin Uedron 5040 sand, 1.0% by weight (based on sand)
of modified Epon 828 resin and milled for 3 minutes.
The composition used contained 80% Epon 828, 10% phenolic resin, 0.2% A-187 silane, 10% methanol, to which was added 20% furfuryl glycidyl ether. This furfuryl glycidyl ether was produced by reacting epichlorohydrin with furfuryl alcohol using a base such as sodium hydroxide as a catalyst for dehydrohalogenation. 30 to the mixture
% (by weight of resin) of cumene hydroperoxide was added and the resulting mixture was milled for an additional 3 minutes. The sand-resin-peroxide mixture was then forced or poured into a mold (standard dogbone mold test mold) and gassed with sulfur dioxide for approximately 0.5 seconds at room temperature, followed by air purge for 20 seconds.
Gas treatment time of about 0.3 to about 5 minutes and room temperature to about
Temperatures of 150°C (300°C) could be used. The product obtained after 20 seconds was ready for use as described above. This product had a significantly higher instantaneous tensile strength than the unmodified product. This product also had hardness and tensile strength equal to or better than similar products made using condensate resins. This type of sand/resin composition also had excellent thermal stability. This method could be similarly performed using bisphenol-F type epoxy resin. Pot life test A series of experiments were conducted to test the epoxy resin/peroxide/
The pot life of sand mixtures as well as the influence of different types of sand were evaluated. Example 9 In a series of tests, Manley 1-L sand was mixed with 1.0% by weight (based on sand) of modified Epon 828 resin;
Grind for 3 minutes. The composition used was 82% Epon 828, 5% resorcinol resin, 3% triphenyl phosphite, 0.2% A-187 silane,
It contained 10% methanol. Then 30% by weight (based on the resin weight) of cumene hydroperoxide was added to the mixture and the resulting mixture was
Pulverized for minutes. The sand-resin-peroxide mixture was then held for 5 minutes, 65 hours and 6 days, respectively.
It was then pressed or poured into a mold (standard dogbone molding test mold) and gassed with sulfur dioxide for about 0.5 seconds at room temperature, followed by air purging for 15 seconds. Gas treatment times from about 0.3 seconds to about 5 minutes and temperatures from room temperature to about 150°C (300°C) could be used. Tensile strength and hardness data for these products were obtained after the following periods:

[Table] This procedure could be carried out similarly using bisphenol-F type epoxy resin and novolac resin. Example 10 In another series of tests, 5040 Oedron sand
It was mixed with 1.0% by weight (based on sand) of modified Epon 828 resin and ground for 3 minutes. The composition used was 82%
Epon 828, 5% resorcinol, 3% triphenyl phosphite, 0.2% A-187 silane, and 10% methanol. To this mixture 30% by weight (based on resin weight) peroxide was added and the resulting mixture was milled for an additional 3 minutes. The sand-resin-peroxide mixture was held for 5 minutes, 65 hours and 6 days respectively, then pressed or poured into a mold (standard dogbone molding test mold) and gassed with sulfur dioxide for about 0.5 seconds at room temperature. death,
After that, air was replaced for 15 seconds. Gas treatment times of about 0.3 seconds to about 5 minutes and temperatures of room temperature to about 150°C could be used. Tensile strength and hardness data for these products were obtained after the following periods:

[Table] This procedure could be carried out similarly using bisphenol-F type epoxy resin and novolac resin. Epoxy Resin vs. Furan Resin in Lakesand A series of tests were conducted to evaluate the products obtained by bonding Lakesand with epoxy resin as well as with furan resin at various amounts. Example 11 In a series of tests, Manley 1-L lake sand was mixed with resin and ground for 3 minutes. Then peroxide was added to this and the resulting mixture was further heated for 3
Pulverized for minutes. This procedure was repeated for epoxy resins as well as for furan resins at three different amounts and for two different peroxides. The sand-resin-peroxide mixture was then pressed or poured into a mold (standard dogbone mold test mold) and gassed with sulfur dioxide for approximately 0.5 minutes at room temperature, followed by a 15 second purge with air. Gas treatment times of about 0.3 seconds to about 5 minutes and temperatures of room temperature to about 150°C could be used. The epoxy resin used was Epon 828 with other materials added, and the composition used was 82% Epon 828, 5% resorcinol resin, 3% triphenyl phosphite, and 0.2% A-187 silane. , containing 10% methanol. To this composition 30% by weight (based on resin weight) peroxide was added and the resulting mixture was ground for an additional 3 minutes before molding. The furan resin was a furfuryl alcohol formaldehyde copolymer reacted under acidic conditions. The ratio of formaldehyde to furfuryl alcohol was 1. The tensile strength and hardness data for products obtained with different resins and different peroxides are shown below:

[Table] This method could be similarly carried out using bisphenol-F type epoxy resin and epoxy novolak resin. Example 12 Evaluation of Different Epoxy Resin-Sand-Peroxide Mixtures In this series of tests, 5040 Uedron silica sand was mixed with the resin and ground for 3 minutes. Peroxide was added to this mixture and the resulting mixture was milled for an additional 3 minutes. This procedure was also repeated for two different epoxy resin compositions in two different amounts and for two different peroxides. Thereafter, the sand-resin-peroxide mixture was pressed or poured into a mold (standard dogbone mold test mold) and gassed with sulfur dioxide for about 0.5 seconds at room temperature, followed by air purge for 15 seconds. Gas treatment times of about 0.3 seconds to about 5 minutes and temperatures of room temperature to about 150°C could be used. The epoxy resin used was Epon 828 with other materials added. Composition A is 80% Epon 828,
Composition B shall contain 15% furfuryl alcohol, 5% resorcinol resin, 0.2% A-187 silane; Composition B will contain 82% Epon 828, 5% resorcinol resin, 3% triphenyl phosphite, 0.2% A-187 silane containing 10% methanol. To these compositions 30% by weight (based on resin weight) of cumene hydroperoxide was added and the resulting mixture was ground for an additional 3 minutes before molding. The tensile strength and hardness data for products obtained with different resins and different peroxides are shown below:

[Table] This method could be similarly carried out using bisphenol-F type epoxy resin and novolac resin. Example 13 In this series of tests, Manley 1-L lake sand was mixed with resin and ground for 3 minutes. Peroxide was added to this mixture and the resulting mixture was milled for an additional 3 minutes. Note that this procedure was similarly performed for two different epoxy resin compositions in the same amounts, as well as for two different peroxides. The sand-resin-peroxide mixture was then pressed or poured into a mold (standard dogbone mold test mold) and gassed with sulfur dioxide for 0.5 seconds at room temperature, followed by air purge for 15 seconds. Gas treatment time of about 0.3 seconds to about 5 minutes and room temperature to about 150℃ (300℃)
〓) temperature could be used. The epoxy resin used was Epon 828 mixed with other materials. Composition B is 82% Epon 828;
Composition C contains 5% resorcinol resin, 3% triphenyl phosphite, 0.2% A-187 silane, 10% methanol, and composition C contains 80% Epon 828, 15% methanol, 5% resorcinol and It contained 0.2% A-187 silane. 30% by weight (relative to resin weight) in these compositions.
of peroxide was added and the resulting mixture was milled for an additional 3 minutes before molding. Tensile strength and hardness data for products obtained using different resins and different peroxides are shown below.

[Table] This method could be similarly carried out using bisphenol-F type epoxy resin and novolac resin. Example 14 In this series of tests, sand was mixed with resin and
Grind for 3 minutes. Peroxide was added to this mixture and the resulting mixture was milled for an additional 3 minutes. still,
This procedure was similarly performed with three different sands, three different epoxy resin compositions, and two different amounts. Cumene hydroperoxide was used as the peroxide. After that, the sand-resin-peroxide mixture was molded (standard dogbone molding test mold).
0.5 at room temperature.
It was gassed with sulfur dioxide for 1 second and then replaced with air for 15 seconds. Gas treatment times from about 0.3 seconds to about 5 minutes and temperatures from room temperature to about 150°C (300°C) could be used. The epoxy resin used was Epon 828 mixed with other materials. Composition D is 75% Epon 828;
15% furfuryl alcohol polymer, 0.2% A
-187 silane and 10% methanol, composition B is 82% Epon 828, 5% resorcinol, 3% triphenyl phosphite,
Composition E shall contain 0.2% A-187 silane and 10% methanol, and composition E shall contain 80% Epon 828,10
% phenolic resin, 0.2% A-187 silane, 10
% methanol. To these compositions 30% by weight (based on resin weight) of cumene hydroperoxide was added and the resulting mixture was ground for an additional 30 minutes before molding. The tensile strength and hardness data for products obtained with different resin compositions and different sands are shown below:

【table】

[Table] This method could be similarly carried out using bisphenol-F type epoxy resin, epoxy novolac resin, furfuryl glycidyl ether, etc. Example 15 Uedron 5040 sand was mixed with 1.0% by weight (based on the weight of the sand) Epon 828 resin and milled for about 3 minutes. The Epon 828 resin was modified with 20% trimethylolpropane triacrylate (TMPTA), which was then mixed with 10% methanol and 0.2% A-
187 silane. Then add 30 to this mixture
% (by weight of resin) of cumene hydroperoxide was added and the resulting mixture was milled for an additional 3 minutes. This mixture is then pressed or poured into a standard dogbone mold test mold, gassed with sulfur dioxide for approximately 0.5 seconds at ambient temperature, and then
Air was replaced for seconds. Tensile strength and hardness data for the test compacts were obtained after the following time periods: For comparison, the above procedure was repeated using Epon 828 with 30% peroxide instead of triacrylate:

Table: As seen above, modification of bisphenol-A epoxy resin with 20% triacrylate increased the tensile strength by 75% in the first 20 seconds after gas treatment. Additionally, the significant increase in article stiffness has enabled the molding of thinly defined, complex cores such as water jacket and cylinder head cores. Another advantage is that the peroxide concentration required for curing is reduced. Example 16 Uedron sand was mixed with 75 parts of epoxy-novolac resin (EPN-1139 manufactured by Ciba Geigi);
1.0% by weight (based on the weight of sand) of a mixture containing 25 parts Epon 828 mixed with 10% methanol and 0.2% A-187 silane was mixed. peroxide 20
Test bodies were prepared as described in Example 15 using the above and similar formulations, except that 7% of trimethylolpropane triacrylate (TMPTA) was reduced to . For comparison, a test molded body of unmodified Epon 828 was also produced. The tensile strength and hardness data for the test compacts produced in this example are shown below:

TABLE These results indicate that the mixture of epoxy and epoxy novolac produces stronger cores than epoxy resin alone. It has also been found that the admixture produces a stronger core than epoxy novolak alone. Furthermore, the above data shows that excellent results can be obtained when the epoxy resin blend is modified with TMPTA even when the amount of peroxide is reduced. Example 17 Uedron sand with 0.2% A-187 silane and 10%
Epoxy novolac resin (EPN-1139) containing only methanol, or 45% epoxy novolac resin EPN-1139 and 45% Epon 828, 0.2%
A-187 silane and 1.0% by weight (based on the weight of the sand) of a blend of 10% methanol.
Cumene hydroperoxide (30% by weight) was then added to the resin blend and the resulting resin mixture was ground. Thereafter, a test molded body was produced according to Example 15. The tensile strength and core hardness data are shown below:

TABLE The above data demonstrate that superior strength is obtained when a combination of resins is used in the compositions of the present invention. Additionally, various other binders commonly used in the manufacture of foundry molds and cores using sulfur dioxide as a hardening agent in combination with an oxidizing agent may be used to make the resins with small amounts of acid hardening of the type mentioned above. It has been found that this can be improved by mixing with epoxy resin at the initial stage. More particularly, it has been shown that the strength of molds and cores produced, for example, with ethylenically unsaturated monomeric binder materials can be increased by the incorporation of small amounts, i.e. up to 50% by weight, of acid-curing epoxy resins. I found it. Incidentally, such ethylenically unsaturated monomer binder materials include those described in British Patent No. 2066714, and generally contain 1 to 1.
There are tetrafunctional acrylates, as well as acid curable condensation resins containing polyfurfuryl alcohol as described in US Pat. No. 4,176,114. An example of this is shown in the following example. Example 18 An acrylic resin was prepared using 2.5 moles of acrylic acid, 1 mole of diethylene glycol, 3 g of concentrated sulfuric acid, and
It was prepared by mixing 0.3 g of hydroquinone and reacting the mixture at about 95° C. for 3 hours in the presence of air. The resulting mixture was then washed with distilled water and excess water was removed by vacuum distillation. A portion of this acrylate product was modified with 30% by weight Epon 828 resin and 0.2% Z-6075 silane,
The rest was modified with only 0.2% Z-6075. Nao Z-
6075 is vinyltriacetoxysilane manufactured by Dow Corning. 20g of Epon 828 modified acrylic resin, 2000g
of Uedron 5040 silica in a Hobart mixer at low speed for 2 minutes.
Cumene hydroperoxide (1.6 g) was then added to this mixture and mixed in the same manner. Standard dogbone tensile test compacts were prepared and gassed with 100% sulfur dioxide for 0.5 seconds. The tensile strength of this test molded product after 20 seconds was 8.437Kg/cm ²
(120psi), the core hardness at that time was 85, 5
Tensile strength after minutes is 17.577Kg/cm ² (150psi)
The core hardness at that time was 85. Similar tests performed on test bodies made from acrylate modified with silane (not Epon 828) showed that the tensile strength after 20 seconds was
At 5.625Kg/cm ² (80psi), the core hardness at that time is 65 and the tensile strength after 5 minutes is 6.328Kg/cm ²
(90psi) and the core hardness at that time was 65. The above results show that the tensile strength of the acrylic resin used in the sulfur dioxide treatment method can be increased by modifying the acrylic resin with an acid-curable epoxy resin. Similar results are obtained when furan resins are modified with small amounts of acid-curing resins. Oxidizing agents that can be used in any of the above examples include various organic peroxides, hydroperoxides or hydroxy-hydroperoxides, or mixtures thereof with hydrogen peroxide, especially cumene hydroperoxide, para Menthane hydroperoxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, and/or methyl ethyl ketone peroxide, or mixtures thereof with hydrogen peroxide.

Claims (1)

[Scope of Claims] 1. 50 to 90% by weight of an epoxy resin selected from the group consisting of bisphenol A, B, F, G and H type epoxy resins and epoxy-novolak resins.
and 10 to 50% by weight of peroxide. 2. The composition according to claim 1, wherein the peroxide is an organic peroxide, a hydroperoxide, a hydroxy-hydroperoxide, a mixture thereof, or a mixture of these and hydrogen peroxide. 3 The organic peroxide is metal ethyl ketone peroxide, cumene hydroperoxide, paramenthane hydroperoxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, a mixture thereof, or a mixture of these and hydrogen peroxide. A composition according to scope 2. 4 The epoxy resin is a modified epoxy resin containing up to 50% by weight of an acrylic or vinyl monomer, furfuryl alcohol, polyfurfuryl alcohol, resorcinol, a formaldehyde-based thermosetting resin, a urethane resin, or a mixture thereof. A composition according to claim 1. 5. The composition according to claim 4, wherein the formaldehyde-based thermosetting resin is a phenol formaldehyde resin or a urea formaldehyde resin. 6. The composition according to claim 4, wherein the acrylic monomer is a monofunctional, difunctional, trifunctional or tetrafunctional acrylate. 7 (a) an inorganic solid particulate material; (b) (i) based on the weight of said particulate material selected from the group consisting of bisphenol A, B, F, G and H type epoxy resins and epoxy-novolac resins; A curable epoxy resin composition comprising 0.2 to 15% by weight of an epoxy resin and (b) 10 to 50% by weight of peroxide based on the weight of the resin. 8. The composition according to claim 7, wherein the peroxide is an organic oxide, a hydroperoxide, a hydroxy-hydroperoxide, a mixture thereof, or a mixture of these and hydrogen peroxide. 9. Claim No. 9, wherein the organic peroxide is methyl ethyl ketone peroxide, cumene hydroperoxide, paramenthane hydroperoxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, a mixture thereof, or a mixture of these and hydrogen peroxide. Composition according to item 8. 10 A modified epoxy resin in which the epoxy resin contains up to 50% by weight of an acrylic or vinyl monomer, furfuryl alcohol, polyfurfuryl alcohol, resorcinol, a formaldehyde-based thermosetting resin, a urethane resin, or a mixture thereof. The composition according to claim 7, which is 11. The composition according to claim 10, wherein the formaldehyde-based thermosetting resin is a phenol formaldehyde resin or a urea formaldehyde resin. 12. The composition of claim 7, wherein the inorganic solid particulate material is sand. 13. The composition of claim 7, wherein the inorganic solid particulate material comprises inorganic abrasive particles. 14. The composition according to claim 10, wherein the epoxy resin is modified with a monofunctional, difunctional, trifunctional or tetrafunctional acrylate.