JPS61238439A - Production of resin for casting - Google Patents

Abstract

PURPOSE:To form a resin for casting having an excellent easy collapsing property by bringing phosphate and/or phosphite at a specific ratio into ester exchange reaction with bisphenol then bringing formaldehyde into reaction. CONSTITUTION:0.1-1.0mol phosphare and/or phosphite is brought into reaction with 1.0mol bisphenol A to execute an ester exchange and thereafter 1.0-5.0mol formaldehyde is brought into reaction in the production of the resin for casting. The resin for casting having the excellent collapsing property even with mechanical impact is thus formed without requiring a long-term heating treatment after casting.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a resin for foundries, and is particularly used in the production of castings such as aluminum castings whose casting temperature is relatively low. The present invention relates to a method for producing a foundry resin that significantly improves mold disintegration properties.

[Conventional technology]

General casting resin is a resin obtained by reacting phenol and formaldehyde in acidic or alkaline conditions.
When these phenolic resins are used in foundry sand molds such as aluminum castings where the casting temperature is low, a large amount of cost and labor is required to remove the sand after casting.

In other words, when these phenolic resins are used, the bait mold retains its strength even after casting because the pouring temperature is low, and it is then heat treated at a high temperature of about 500℃ for 4 to 10 hours. After casting, the mold will not collapse unless an impact is applied, and post-processing after casting requires an extremely large amount of cost and labor.

[Problem that the invention seeks to solve]

The present invention provides a method for producing a casting resin that does not require long-term heat treatment and has extremely excellent disintegration properties that can be disintegrated by mechanical impact alone.

[Means for solving problems]

In the present invention, 0 phosphoric acid esters and/or sulfite esters per 1.0 mol of bisphenol A,
A casting resin is produced by carrying out a 1 to 1.0 mol@xx chill Z exchange reaction and then reacting 1.0 to 5.0 mol of formaldehyde in total. The mold has excellent collapsibility after pouring, and it is possible to collapse the mold only by mechanical impact without heat treatment after pouring.

Phosphate esters used in the present invention include tributyl phosphate, triethyl phosphate, tributyl phosphate, triocti/l/yjC sulfate,
These include tryptoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, tricylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, trilauryl phosphate, tristearyl phosphate, and the like.

Phosphites include trimethyl phosphite, tributyl phosphite, triphenyl phosphite, tridodecyl phosphite, dimethyl phosphite,
These include diethyl phosphite and diptylphosphite.

Phosphate ester, phosphite ester, or a mixture thereof is used in amounts of Q1 to 1.0 mol per 1.0 mol of bisphenol A.

If it is less than 0.1 mol, the effect of improving disintegration is small, and if it exceeds 1.0 mol, it has the disadvantage that curing becomes slow, which is not preferable.

A catalyst is used to carry out the transesterification reaction between bisphenol A, phosphoric acid ester, and phosphorous ester. Examples of catalysts include carbonates such as potassium carbonate, sodium carbonate, and lead carbonate, metal oxides such as zinc oxide and barium oxide, metal hydroxides such as sodium hydroxide and potassium hydroxide, and amines such as triethylamine and diethylamine. types can be used.

As formaldehyde, formalin, paraform, etc. can be used. Formaldehyde is bisphenol A1
, 1.0 to 5.0 mole/+4' to 0 mole.

If it is less than 1.0 mol, unreacted bisphenol A will increase, resulting in slow curing, and if it exceeds 5.0 mol, the resin will gel (9) and the odor of formaldehyde will become strong, which is not preferable.

A catalyst is used when formaldehyde is reacted.

As a catalyst, acids such as hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, oxalic acid, or sodium hydroxide, hydration power +1
alkalis such as calcium hydroxide, ammonia trimethylamine, diethylamine, triethylamine,
Amines such as hexamethylenetetramine can be used.

Examples and comparative examples of the present invention will be described below.

〔Example〕

Example 1 228 g of bisphenol A, 163 g of triphenyl phosphate, and 6.9 g'i of potassium carbonate were placed in a 94-meter flask equipped with a stirrer, a reflux condenser, and a thermometer.The mixture was heated on an oil bath and reacted at 160'C for 4 hours. After cooling, 50 g of acetone was added and dissolved. 37% formalin 20
After reacting at reflux temperature for 3 hours, 3 g of oxalic acid and 12.6 g of oxalic acid were added, and the mixture was concentrated under reduced pressure. When the internal temperature reached 150"C, the plate was taken out.

Example 2 228 g of bisphenol A, 62 g of triphenyl phosphite, and 6.9 g of potassium carbonate were placed in a four-way flask equipped with a stirrer, a reflux condenser, and a thermometer, heated on an oil bath, reacted at 160'C for 4 hours, and then cooled. Then, 50 g of acetone was added and dissolved. 37% formalin 203 g
, 12.6 g of oxalic acid was added and after reacting at reflux temperature for 3 hours,
Concentration under reduced pressure was carried out, and the plate was taken out just in case the internal temperature reached 150"C. @Example 3 228 g of bisphenol A, 130 g of triphenylphos 7A, carbonic acid Add 4.6 g of potassium, raise the temperature on an oil bath and react at 150°C for 1 hour. Cool, add 50 g of acetone and dissolve. Next, add 243 g of 37% formalin and 5 g of methylenetetramine A and react at 80° C. for 6 hours. After concentration under reduced pressure, the plate was taken out when the internal temperature reached 95°C.

Comparative Example: In a Yotsuro flask equipped with a stirrer, a MilF, a condenser, and a thermometer, 188 g of phenol, 37.5 g of 80% paraformaldehyde, 7 g of 37% formalin, and 04 gft of IN hydrochloric acid were heated on an oil bath and the reaction solution was heated at the upstream temperature. The mixture was allowed to react until emulsified. Thereafter, the reaction was carried out at reflux temperature for 2 hours, and then concentrated under reduced pressure, and when the internal temperature reached 150°C, the plate was taken out.

In order to compare the properties of the NFCA oils obtained in Examples and Comparative Examples, resin-coated sand was produced under the following conditions.

8 kg of Fremantle silica sand heated to 150℃ and 1 resin
44g and kneaded for 40 seconds with Speed Mikina, and then
Add 144 g of % hexamethylenetetramine aqueous solution to 6
After mixing for 0 seconds, add 8g of calcium stearate and
The mixture was mixed for 0 seconds and discharged to obtain resin-coated sand. However, in Example 3, 120 g of water was added instead of the 15% Fi hexamethylenetetramine aqueous solution.

Table 1 shows the properties of the resin-coated sand obtained.

Table 1 Measuring method Melting point: Based on JACT shell work standards.

Bending strength: Based on JIS K-6910.

Disintegration rate: 30φ x 5011111 heated to 250℃
A test piece was prepared by placing resin-coated gold dust in a mold H and curing it in an electric furnace at 400°C for 3 minutes.

At 500℃ maintained in an oxygen-free condition Enclosed in a heated mold, 500 After baking in the oven for 20 minutes, Cool. This test piece guise 2 8 Rotala on a mesh sieve Shake for 1 minute using a sieve shaker and 5 machines. From the amount of decrease, use the following formula: The decay rate was calculated.

〔Effect of the invention〕

As is clear from the results shown in Table 1, according to the present invention, it is possible to produce a foundry resin with excellent disintegration properties.

Claims (1)

[Claims] 1. After transesterification by reacting 1.0 mole of bisphenol A with 0.1 to 1.0 mole of phosphoric acid esters and/or phosphite esters, 1.0 to 1.0 mole of formaldehyde is transesterified. A method for producing a foundry resin, characterized by reacting 5.0 mol. 2. The method for producing a foundry resin according to claim 1, wherein the phosphoric acid ester is triphenyl phosphate. 5. The method for producing a foundry resin according to claim 1, wherein the phosphite is triphenyl phosphite.