JPH0325255B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a composition that is used when forming a mold by adding gaseous or aerosol sulfur dioxide to a sand mold made by adding and kneading acid-curable resin and peroxide to fire-resistant granular aggregate. The present invention relates to curable mold compositions having peroxide compositions containing certain dilution stabilizers. Conventionally, in order to manufacture molds at high speed, a shell molding method has been used in which so-called resin coated sand, in which refractory granular aggregate is coated with phenolic novolac resin, is molded and heat cured. However, in order to save energy during mold manufacturing, mold production speed, and improve the production quality of molds and castings, the so-called cold box method, in which molds are manufactured by chemical reaction at room temperature by adding gas and hardening, has been replaced. The foundry industry is seriously considering its introduction as a mold manufacturing method. Currently, cold box methods include the so-called furan cold box method, in which acid-curing resins such as furan resin are cured with sulfur dioxide using peroxide as an oxidizing agent, and polyols and polyisocyanates are cured using an aerosol of tertiary amine as a catalyst. There is a urethane cold box method that hardens, and the Franco cold box method, which has been proven to have good results in the field of manufacturing high-mix, low-volume castings due to its self-hardening properties, has recently been rapidly attracting attention. One of the drawbacks of the shell mold method is that the mold does not easily disintegrate during the disassembly process after internal pouring in the casting manufacturing process, and especially for aluminum castings, it is necessary to perform heat treatment to remove the sand mold of the core. An alternative molding process is required in order to save energy and streamline the process. The present inventors have arrived at the present invention as a result of intensive research to further improve the disintegration of the Francold Box method, which has good disintegration among high-speed mold making methods. That is, the present invention involves adding and kneading an acid-curing resin and a peroxide composition to a fire-resistant granular material, and molding the resulting sand mold.
A composition used when producing a mold by blowing gaseous or aerosol sulfur dioxide, the composition comprising:
The peroxide composition contains 40-60% by weight of hydroperoxide or ketone peroxide and a dilution stabilizer.
60 to 40% by weight, and the dilution stabilizer has the general formula
A curable mold containing 30 to 100% by weight of at least one methyl ester of an aliphatic dibasic acid represented by HOOC(-CH ₂ -) _o COOH (n = 1 to 10). This relates to a composition. The dilution stabilizer may be only the methyl ester of the aliphatic dibasic acid represented by the above general formula, but it may contain up to 70% by weight of a known peroxide dilution stabilizer. Such dilution stabilizers include the following [I]~
One or more of the compounds represented by [V] may be used, but if the amount exceeds 70% by weight, the effect of improving mold disintegration will be insufficient. [I]

[Formula] (In the formula, n is 1 to 3, and when n = 1, X is an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, aryl group, or aralkyl group having 1 to 20 carbon atoms. n = In the case of 2, X is an alkylene group having 2 to 26 carbon atoms, an alkenylene group, an alkynylene group, a cycloalkylene group, a phenylene group, an aralkylene group, or an alkyl substituent thereof. In the case of n=3

【formula】

【Formula】Also teeth

[Formula] is. For n=1 to 3, R ₁ may be the same or different, and the sum of all the carbon numbers of R ₁ is n
~60 alkyl groups, alkenyl groups, alikynyl groups, cycloalkyl groups, aryl groups, aralkyl groups, or halogen, alkoxy, acyloxy, or alkoxycarbonyl substituted products thereof. ) []

[]

(In the formula, R ₄ , R ₅ , R ₆ are hydrogen atoms, or alkyl groups or alkenyl groups having a total number of carbon atoms of 1 to 60,
They are an alkynyl group, a cycloalkyl group, an aryl group, or an aralkyl group. However, at least one of R ₄ , R ₅ , and R ₆ is not a carbon atom. ) [] Phosphorus esters

【formula】

【formula】 or

[Formula] (In the formula, R ₇ , R ₈ , R ₉ are hydrogen atoms or have 1 to 1 carbon atoms.
20 alkyl groups, alkenyl groups, alkynyl groups,
An aryl group, an aralkyl group, or a halogen-, alkoxy-, or acyloxy-substituted product thereof. However, at least one of R ₇ , R ₈ , and R ₉ is not a hydrogen atom. ) In the present invention, at least one methyl ester of an aliphatic dibasic acid represented by the general formula HOOC (-CH ₂ -) _n COOH (where m = 2 to 8) is used as a dilution stabilizer in an amount of 50 to 100% by weight. It is preferable to use one containing %. Further, as the peroxide, hydroperoxide and ketone peroxide are used, and ketone peroxide is preferably used. Normally, 0.5 to 3 parts by weight of the acid-curing resin and 0.1 part by weight of the peroxide composition per 100 parts by weight of the fire-resistant granular material.
Gaseous or aerosol sulfur dioxide is blown into the molded sand mold by adding ~1 part by weight and kneading to produce a mold. As the refractory granular aggregate, silica sand containing quartz as a main component, zircon sand, chromite sand, etc. are used, but the present invention is not limited to these. As the acid-curable resin, furan resin, phenol resin, urea resin, or a copolycondensate or mixture thereof is used, but the present invention is not limited to these acid-curable resins. The advantages of the present invention will be explained in more detail with reference to examples, but the scope of the present invention is not limited by the following examples. Examples 1 to 5 and Comparative Examples 1 to 3 1000 parts by weight of silica sand contains 12 parts by weight of furan resin, the same amount of methyl ethyl ketone peroxide and the dilution stabilizer listed in Table 1, and the amount of active oxygen is 10%. A mixture obtained by adding and kneading 5 parts by weight of the methyl ethyl ketone peroxide composition was heated to 50 m/mφ
After filling the mH mold, a mold was formed by passing sulfur dioxide for 1 second and compressed air for 5 seconds. The formed mold was heated in a furnace at 750°C for 5 minutes and its compressive strength was measured, and the ease with which the mold would collapse was determined by the strength before and after heating. The results are shown in Table-1.

[Table] Examples 6 to 7 and Comparative Examples 4 to 5 Tests were conducted in the same manner as in Example 1 using methyl ethyl ketone peroxide compositions with different ratios of dimethyl adipate and diisopropyl adipate as dilution stabilizers. The results are shown in Table-2.

【table】

Claims (1)

[Scope of Claims] 1 Used when manufacturing a mold by blowing gaseous or aerosol sulfur dioxide into a sand mold made by adding and kneading an acid-curing resin and a peroxide composition to a fire-resistant granular material. a composition, wherein the peroxide composition comprises 40-60% by weight of a hydroperoxide or ketone peroxide and 60-40% by weight of a dilution stabilizer;
The dilution stabilizer has the general formula HOOC (-
A curable mold composition containing 30 to 100% by weight of at least one methyl ester of an aliphatic dibasic acid represented by CH2- ₎ oCOOH (where n=1 to ₁₀ ). 2 The dilution stabilizer of the peroxide composition has the general formula
Claim 1, which contains 50 to 100% by weight of at least one methyl ester of an aliphatic dibasic acid represented by HOOC(-CH ₂ -) _n COOH (where m = 2 to 8) curable mold composition.