JPS6352736A - Resin binder for shell mold - Google Patents

Abstract

PURPOSE:To obtain a resin binder for a shell mold which collapses with the mechanical impact alone while a heat treatment is not always required after casting by mixing phosphate and halogenated inorg. compd. respectively at specific % into a phenolic resin. CONSTITUTION:This resin binder improves the collapsing property of a casting mold after casting when used for production of catings having a relatively low casting temp. such as aluminium casting and alloy casting. A novolak type phenolic resin, resol type phenolic resin, and the mixture and molten mixtures thereof are usable as the phenolic resin. The resin binder prepd. by mixing 2-50 pts. wt. phosphate and 0.1-1.0 pts. wt. halogenated inorg. compd. in 100 pts. wt. phenolic resin is used. The collapsing property after the casting is thereby improved and the need for the heat treatment after the casting is eliminated by using such binder.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a resin binder for shell molds, and is particularly used in the production of castings with relatively low casting temperatures, such as aluminum castings and alloy castings. This invention relates to a resin binder for shell molds that has significantly improved disintegration properties after casting.

[Conventional technology]

Generally, the binder used in resin-coated sand for foundries is a resin obtained by reacting phenol and formaldehyde in an acidic or alkaline environment. When used in sand molds, very large costs and labor are required to remove the sand after casting.

Zunawaji, when these phenolic resins are used,
Even after pouring, the mold still maintains its strength due to the low pouring temperature, and after being heat treated at a high temperature of around 500℃ for 6 to 12 hours, the mold will not collapse unless an impact is applied.
Post-processing after casting requires an extremely large amount of cost and labor.

In particular, with recent calls for energy savings, there is a strong demand for resin binders for shell molds that do not require heat treatment after casting.

[Problem that the invention seeks to solve]

The present invention aims to provide a resin binder for shell molds that does not necessarily require post-casting heat treatment and disintegrates only by mechanical impact.

[Failure to solve the problem]

The resin binder for shell molds of the present invention is characterized in that 2 to 50 parts by weight of a phosphoric acid ester and 0.1 to 1.0 parts by weight of a halogenated inorganic compound are melted to 100 parts by weight of a phenolic resin. do.

100 to 20 using coated sand coated with the binder of the present invention.
The molds manufactured at 0°C had significantly improved collapsibility compared to conventional molds, and as a result, it was revealed that they could collapse only by mechanical impact without post-casting heat treatment.

As the phenolic resin used in the present invention, novolac type phenolic resins, resol type phenolic resins, and mixtures and melts thereof can be used. In addition to the commonly used phenolpolmaldehyde novolac type phenolic resin, the novolak type phenolic resin includes
So-called high-ortho novolac resins modified with alkylphenols. Novolac type resin can be used.

Resol type phenolic resins that can be used in the present invention include resol type phenolic resins obtained using alkali metal or alkaline earth metal hydroxides as catalysts, resol type phenolic resins obtained using ammonia or amines as catalysts, ammonia or amines, etc. A resol-type phenolic resin obtained by a combined catalyst with a hydroxide of an alkali metal or an alkaline earth metal, etc. can be used.

In the present invention, it is very preferable to use a solid resol type phenol resin obtained by using ammonia or amines as a catalyst. So-called ammonia resol resins, which are obtained using ammonia or amines as catalysts, have nitrogen-containing bonds called N-methylene in their molecules, so they are more heat resistant than novolac-type phenolic resins, which only have methylene bonds. This is thought to be due to the low disintegration properties.

It is also possible to produce resin-coated sand using a combination of the novolac type phenolic resin binder and the resol type phenolic resin binder.

Further, it is preferable to use a mixture of a resol type phenol resin and a novolac type phenol resin as the phenol resin because mold strength is improved.

When using a novolak type phenolic resin and a resol type phenolic resin in combination or by mixing them, the ratio of both is as follows:
Although not particularly limited, Redzul type phenolic resin 10
It is desirable that the amount of the novolac type phenol resin be 60 parts by weight or less relative to 0 parts by weight. This is because too much novolac type phenolic resin slows down the curing speed.

However, 7. When using hexamethylenetetramine or the like as a curing agent, up to 200 parts by weight can be used.

The phosphoric acid esters used in the present invention include trimethyl phosphate, 1-ethyl phosphor I, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, trischloroethylbosphate, trischloropropyl phosphate, Phenyl phosphate, tricresylboshe 1-, tricylenyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, xylenyl diphenyl phosphate, trilauryl phosphate, tricetyl phosphate, tristearyl phosphate, Orthophosphoric acid esters such as trioleyl phosphate, trimethyl phosphite, triethyl phosphite, tributyl phosphite, triphenyl phosphite, tridodecyl phosphite, trisnonylphenyl phosphite, trischloroethyl phosphite, tristridecyl phosphite Phosphite triesters, dimethyl phosphite, diethyl phosphite, etc.
Phosphite diesters such as dibutyl phosphite Phosphonate esters such as dibutyl, butyl phosphonate, di(2-ethylhexyl) phosphonate, etc. can be used.

The halogenated inorganic compounds used in the present invention include cupric chloride, magnesium chloride, calcium chloride, barium chloride, aluminum chloride, manganese chloride, ferrous chloride, ferric chloride, cobalt chloride, nickel chloride, and zinc chloride. , chlorinated inorganic compounds such as sulfur chloride, stannous chloride, lead chloride, zinc bromide, aluminum bromide, calcium bromide, cobalt bromide, cupric bromide, nickel bromide, magnesium bromide, Brominated inorganic compounds such as manganese bromide, iodinated inorganic compounds such as zinc iodide, aluminum iodide, calcium iodide, etc. can be used.

Among these halogenated inorganic compounds, chloride and bromide have a remarkable effect on improving disintegration, and as metal components, iron,
Cobalt and sulfur have great effects.

The phosphoric acid ester is based on 100 parts by weight of the phenol resin.
2 to 50 parts by weight are used. In addition, the halogenated inorganic compound is 0.1 to 100 parts by weight of the phenol resin.
1.0 part by weight is used. When a phosphoric acid ester and a halogenated inorganic compound are used together, if the phosphoric acid ester is less than 2 parts by weight, the effect of improving collapsibility will be small, and if it exceeds 50 parts by weight, the mold strength will decrease and the fusion point of the coated sand will decrease. etc., which is not desirable. If the amount of the halogenated inorganic compound is less than 0.1 part by weight, the effect of improving disintegration will be small, and if it exceeds 1.0 part by weight, the mold strength will decrease and the odor will increase when making the mold or pouring, which is undesirable. .

Both substances are uniformly melted or mixed into the resin.

One method for melting phosphoric esters and halogenated phosphoric esters in novolak-type phenolic resin is to charge phenol, formaldehyde, and an acidic catalyst in a reaction vessel, heat to perform a condensation reaction, and then add phosphoric esters. After that, there is a method of concentrating under reduced pressure, adding a halogenated inorganic compound, and melting it uniformly.

Another method is to add a phosphoric acid ester, a halogenated inorganic compound, and if necessary a lubricant and a hardening agent to a solid novolak-type phenolic resin that has been crushed or ground, and then extrude or compression mold the mixture to form a binder. There is a way to manufacture it.

When a phosphoric acid ester and a halogenated inorganic compound are mixed with a resol type phenolic resin, an alkali catalyst is used instead of an acidic catalyst in the above method.

One method for producing a mixture of resol-type phenolic resin and novolac-type phenolic resin, which is a mixture of phosphoric acid ester and halogenated inorganic compound, is to charge phenol, formaldehyde, and an alkali catalyst in a reaction vessel, and conduct a condensation reaction by heating. I do.

Thereafter, a dehydration reaction is performed to dissolve the solid or molten novolac type phenol resin, phosphoric acid ester, and halogenated inorganic compound. In this case, the novolac type phenol resin, phosphoric acid ester, and halogenated inorganic compound may be added during the dehydration reaction.

Other methods include extrusion molding or compression molding of coarsely crushed or pulverized solid resol-type phenolic resins, novolac-type phenolic resins, phosphate esters, and halogenated inorganic compounds, with the addition of lubricants and hardeners as necessary. Manufactured by

The phenolic resin used in the present invention may contain, if necessary, a curing agent such as hexamethylenetetramine, a lubricant, a silane coupling agent, etc., which are commonly used in the industry, within a range that does not impede the woody effect of the present invention. May be blended.

It is preferable to include a lubricant in the phenolic resin because it does not improve mold strength or blocking resistance. As lubricants, ethylene bisstearamide, ethylene bisonimate amide, methylene bisstearamide, oxystearamide, swaric acid amide, valmitic acid amide, oleic acid amide, methylolamide, calcium stearate, polyethylene wax, paraffin Wax, Montan wax, and Karunahawasoku hats can be used. The lubricant is preferably used in an amount of 1 to 0 parts by weight per 100 parts by weight of the phenolic resin. If it is less than 1 part by weight, the effect will be small, and if it exceeds 10 parts by weight, the curing speed will be slow and the adhesive force between sand grains will be impaired, which is not preferable. The method of blending the paste is not particularly limited, but it is preferably added at a temperature of 150°C or higher. Further, the mixing time after addition is not particularly limited, but it is preferable to mix for 1 hour or more. Further, the lubricant can also be added when producing foundry sand by kneading the binder and sand after producing the resin.

A silane coupling agent is usually added to increase the adhesive strength between sand and resin.

The silane coupling agent that can be blended into the resin binder for shell molds of the present invention is not particularly limited, but aminosilane coupling agents are preferred, and N-β (
(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropylmethyldimethoxysilane, T-aminopropyltriethoxysilane, etc., and the compounding price is limited to 1) (1j
Although not included, it is preferably 0.05 to 2 parts by weight based on 100 parts by weight of the phenolic resin. If it is less than 0.05 part, the effect of the coupling agent on the strength direction 1- is small, and if it exceeds 2 parts, there is a risk of blocking of the phenol resin, which is not preferable.

[Effect]

Phosphorus compounds have long been widely used as flame transport agents for polymers. Regarding the Minoenka Kajiyoko, there are references (Sc
Hyryten Il, A, etal, Advan
ce, Chem.

According to Ser., 9.7-20 (1954), phosphorus compounds promote the dehydration reaction of polymers containing oxygen in their molecules, such as phenolic resins, and promote carbonization, which improves flame retardancy. It is considered. The present inventors have disclosed in JP-A-61-2453 and JP-A-61-2/154 a resin viscosity in which 10-50 parts of phosphoric acid ester are dissolved in 100 parts by weight of phenolic resin. It has been disclosed that spinning molds made with coated sand using Binder 4 have significantly improved disintegration properties after casting. The effects obtained by this technique are largely due to the carbonization effect of the phosphorus compound, and it is thought that the cohesive force between the phenolic resin and the sand grains, which has been accelerated by carbonization, is reduced, resulting in improved collapsibility. In the present invention, by using a halogenated inorganic compound in the conventional phosphoric acid ester, it is thought that the disintegration property is further improved due to the synergistic effect of the two.

〔Example〕

The present invention will be explained in more detail below based on Examples, but the present invention is not limited to these Examples in any way.

Example 1 Weighed 880 g of phenol, 375 g of 80% paraboraldehyde, 487 g of 37% formalin, and 4 g of IN hydrochloric acid into a four-eye flask equipped with a stirrer and a refluxing condensate temperature of 200 ml, and added the oil without stirring. The mixture was heated on a bath and the reaction was carried out at reflux temperature until the reaction mixture became emulsified. Thereafter, the reaction was carried out at reflux temperature for 2 hours to form I.rifenylvos-t37.
After adding G g, reduce and compress, and ferrous chloride 1
1. Novolac type phenolic resin binder 224.1. in which Og is added and mixed uniformly, and a phosphoric acid ester and a halogenated inorganic compound are melted. g (softening point: 82°C) was obtained.

Example 2 1.880 g of phenol, 375 g of 80% parabomaldehyde, 487 g of 37% formalin, IN in a four-eye flask equipped with stirrer, refrigerated condensate, temperature 5I.
4 g of hydrochloric acid was weighed out and heated in an oil bath while stirring, and the reaction was carried out at reflux temperature until the reaction solution was emulsified. After that 2
The reaction was carried out at reflux temperature for an hour, and triphenylphosphor 1-
After adding 376 g, concentrate under reduced pressure to obtain cobal bromide)
11.0 g of the mixture was added and mixed uniformly to obtain 2241 g of a Nopola 7-ri type phenolic resin binder (softening point: 80°C) in which a phosphoric acid ester and a halogenated inorganic compound were melted.

Example 3 In a four-eye flask equipped with a stirrer, a reflux condenser, and a thermometer, 1880 g of phenol, 375 g of 80% formaldehyde, 487 g of 37% formalin, and 4 IN hydrochloric acid were added.
g was weighed out, heated on an oil bath while stirring, and reacted at reflux temperature until the reaction solution was emulsified. Thereafter, the reaction was carried out at reflux temperature for 2 hours, and after adding 376 g of triphenylphosphor, it was concentrated under reduced pressure to obtain 1 O, Og of sulfur chloride.
was added and uniformly melted to obtain 2240 g of a novolac type phenolic resin binder (softening point: 80°C) in which a phosphoric acid ester and a halogenated inorganic compound were melted.

Example 4 940 g of phenol, 37% formalin in a four-eye flask equipped with a stirrer, reflux condenser, and thermometer], 62
2 g and 23.5 g of 20% caustic soda were weighed out, heated on a hot water bath without stirring, and reacted at 80 to 85°C for 4.5 hours. After that, the temperature was 90-110℃ and the degree of vacuum was 700±1.
Concentration was carried out using OnHg, and the end point was a distillate amount of approximately 1250 g. 180 g of triphenylphosphor) and 5.0 g of ferrous chloride were
was added and melted, then taken out from the flask and resol type phenolic resin binder 1522 with phosphoric acid ester melted.
I want to obtain a softening point of 78°C).

Example 5 In a four-eye flask equipped with a stirrer, reflux condenser, and thermometer, 940 g of phenol and 1622 37% formalin were added.
g, 23.5 g of 20% caustic soda were weighed out, heated on a hot water bath without stirring, and reacted at 80 to 85°C for 4.5 hours. After that, 90-110℃, degree of vacuum 700±],
Concentration was carried out using Omtlg, and the distillation amount was set at the end point at about 1250 g, and 530 g of novolac type phenolic resin binder, 300 g of triphenyl phosphate, and 5.5 g of cobal bromide l-1 were obtained in the same manner as in Comparative Example 1 below. After melting, the mixture was taken out from the flask to obtain 2172 g of a resol type novolac type mixed phenol resin binder in which phosphoric acid ester was melted (softening point: 77°C).

Comparative Example 1 In a four-eye flask equipped with a stirrer, a reflux condenser, and a thermometer, 1880 g of phenol, 375 g of 80% formaldehyde, 487 g of 37% formalin, IN @
Weigh #4 g in the table frame, heat it on an oil bath without stirring,
The reaction was carried out at reflux temperature until the reaction solution became emulsified. Thereafter, the reaction was carried out at reflux temperature for 2 hours, and then concentrated under reduced pressure to obtain 1960 g of a novolak type phenolic resin binder (softening point: 86'c).

Comparative Example 2 In a four-eye flask equipped with a stirrer, a reflux condenser, and a thermometer, 1880 g of phenol, 375 g of 80% paraformaldehyde, 487 g of 37% formalin, and 4 IN hydrochloric acid were added.
g was weighed out, heated on an oil bath without stirring, and reacted at reflux temperature until the reaction solution was emulsified. Thereafter, the reaction was carried out at reflux temperature for 2 hours, and after adding 376 g of triphenyl phosphate, the mixture was concentrated under reduced pressure to obtain 2230 g of a novolank type phenolic resin binder (softening point: 81°C) in which a phosphoric acid ester was melted.

Production of resin-coated sand 8 kg of Freemantle silica sand heated to 150°C and 144 g of each of the binders obtained in Examples 1.2.3.4 and 5 and Comparative Examples 1 and 2 were mixed in a speed mixer for 40 kg. After kneading for seconds, 142 g of a 15% aqueous hexamethylenetetramine solution was added, and after kneading for 60 seconds, 8 g of calcium stearate was added, mixed for 20 seconds, and discharged to obtain resin-coated sand.

For each coated sand obtained, the fusion point, bending strength and disintegration rate were measured, and the odor during molding and pouring was evaluated.

Measuring method Melting point: According to JIS K-6910.

Bending strength: According to JTTS K-691.0.

Disintegration rate: Resin-coated sand is placed in a 30φ x 50nH mold heated to 250°C and cured for 3 minutes in an electric furnace at 400°C to create a test piece. It was sealed in a mold heated to 500°C kept in an oxygen-free condition and heated for 20 minutes in a 500°C furnace.
After baking for a minute, let it cool. This test piece was placed on a 28 mesh sieve and shaken for 1 to 5 minutes using a rotary tube shaker, and the disintegration rate was determined from the amount of decrease using the following formula.

Disintegration rate (%) - As shown in the margin table below, the resin binders for shell molds obtained in Examples 1 to 5 according to the present invention had a lower melting rate than the binders obtained in comparative examples. It has excellent general properties such as bending strength and odor, and is excellent in disintegration.

〔Effect of the invention〕

The resin binder for seal molds according to the present invention has extremely good disintegration properties after casting, does not require heat treatment after casting, and has better shipability and odor than conventional binders. It has no inferiority, and its industrial value is great.

Claims (1)

[Claims] 1. 2 to 50 parts by weight of phosphoric acid ester and 0.1 to 0.1 to 50 parts by weight of halogenated inorganic compound per 100 parts by weight of phenolic resin
A resin binder for shell molds, characterized in that 1.0 parts by weight is mixed therein. 2. The resin binder for shell molds according to claim 1, wherein the phenolic resin is a novolac type phenolic resin. 3. The resin binder for shell molds according to claim 1, wherein the phenolic resin is a resol type phenolic resin. 4. The resin binder for shell molds according to claim 1, wherein the phenolic resin is a mixture of a novolac type phenolic resin and a resol type phenolic resin. 5. The shell mold resin according to claim 1, 2, 3, or 4, wherein the phenol resin contains 1 to 10 parts by weight of a lubricant per 100 parts by weight of the phenol resin. Binder.