JPS5849769A - Method for reusing urea used in precision casting - Google Patents

Abstract

PURPOSE:To obtain an adhesive having long potlife and excellent water resistance, boiling resistance, and weather resistance, by adding an aldehyde, etc. to urea flowed out during the precision casing process, and adding a resorcinol resin to the resultant urea precondensate. CONSTITUTION:Urea flowed out during the precision casting process using urea as the lost material is (preferably after leaving to stand under hot condition and removing the bleeded higher fatty acid and wax from the urea) mixed with an aldehyde such as formaldehyde or an aldehyde donor such as paraformaldehyde, and made to react under heating in the presence of an alkali catalyst to obtain a urea precondensate, which is converted to and utilized as an adhesive by adding a resorcinol resin[a condensation product of resorcinol compound such as resorcinol, alkylresorcinol, etc. and an aldehyde (donor)]. USE:Bonding of wood, textile, plastics, rubber, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for reusing an area used in the precision cleaning method.

In precision casting, a water-soluble substance, a heat-fusible substance, etc. is used as a fugitive substance, and a model similar to the article to be cast is first made using the fugitive substance, and a refractory slurry is applied to the peripheral surface of the model. The mold is manufactured by making a mold, and then dissolving the model inside the mold with water, steam, heat, etc. The method using area as a vanishing substance is particularly called the SUP method. As mentioned above, in the SUP method using area as a fugitive substance, a large amount of area eluate is generated, but in the past, this was incinerated as industrial waste. However, since the area eluate contains a large amount of area, it is not desirable to simply dispose of it by incineration. Therefore, a method has been proposed in which the area eluate is condensed with formaldehyde or the like to form an area resin, and this is used as an adhesive. However, the area eluate in the BUP method contains not only area but also a considerable amount of the eighth component such as polyhydric alcohol, and therefore has better water resistance and boiling resistance than commercially available area resin adhesives. It was not possible to obtain a practical adhesive due to the extremely poor properties and weather resistance.

With the aim of improving the above-mentioned conventional drawbacks and producing highly practical adhesives using the area eluates generated in the precision casting process, and thereby achieving advanced utilization of the area eluates, The gist of this method is to add a resorcinol resin to the initial condensate with aldehyde.

By adding resorcinol resin to the initial condensate of area eluate and aldehyde, a practical adhesive with extremely high water resistance, boiling resistance, and weather resistance can be obtained. In other words, resorcinol-based resins are cured by aldehydes and provide adhesives with great water resistance, boiling resistance, and weather resistance.On the other hand, resorcinol-based resins cure quickly even at room temperature, so the pot life after adding aldehydes is shortened. Although it was short-lived and had limited practicality, the presence of the area eluate extended the pot life, and thus the resorcinol resin, the area eluate, and the initial condensate of aldehyde were mixed and compensated for each other's shortcomings. The present invention, which will provide a highly practical adhesive that does not exist, will now be described in detail.

A model similar to the article to be cast is made by the area using a conventional method for dissolving the area eluates used in the present invention, a mold is made by applying refractory slurry to the peripheral surface of the model, and the area is water-filled from inside the mold. , refers to substances eluted by steam, heat, etc. Generally, the urea eluate contains polyhydric alcohols, higher fatty acids, waxes, etc. in addition to urea, and since higher fatty acids, waxes, etc. will precipitate if the urea eluate is left to warm, it is used after removing these. Area eluates after removal of higher fatty acids and waxes have the following compositions, for example.

Area 75 Weight% polyhydric alcohol t3 Higher fat @ q, g wax
21 Others 2j Water 2I An aldehyde or an aldehyde donor is added to the above-mentioned area eluate and reacted by heating in the presence of an alkali catalyst by a conventional method to form an initial condensate.

The above aldehyde includes all compounds having an aldehyde group such as formaldehyde, acetaldehyde, n-butyraldehyde, acrolein, and 7ran, and decomposition of the above aldehyde supplier and #i paraformaldehyde, hexamethylenetetramine, α-polyoxymethylene, etc. ◇ When producing the above initial condensate, if desired, 1,000 urea, ethylene urea, melamine, guanine, anidine, guanamine, dicyan, diamide, phenol, alkylphenol,
Compounds that can be co-condensed with areas such as furfuryl alcohol, certain - changes the area.

A compound may be added that causes the reaction to occur.

The resorcinol resin added to the above-mentioned initial condensate refers to a condensation product of a resorcinol compound and an aldehyde or an aldehyde donor.

The resorcinol compound herein refers to resorcinol or one or #i2 or more alkyl substituted products of resorcinol. The alkyl group Ifi is a prime number of l to da, and such alkyl groups include methyl group, ethyl group, n-propyl group, 1za-propyl group, n-butyl group, 1zo-butyl group, tart- There are butyl groups, etc. Resorcinol Co., Ltd., which has an alkyl group with a C number of 0 or less as a substituent, is produced as a by-product during dry lacquering of oil shale and can be obtained at low cost. However, since the object of the present invention can be easily achieved even with resorcinol having an alkyl group having 5 or more carbon atoms as a substituent, the present invention is not limited to the number of carbon atoms in the alkyl group. One or more resorcinol compounds may be mixed with each other. In particular, resorcinol compounds that are produced from oil shale during dry distillation include S-methylresorcinol, S-ethylresorcinol, da, 2j-dimethylresorcinol, co,! - Dimethyl resorci, norl, etc.! It is an alkylresorcinol mixture whose main component is substituted alkylresorcinol, and it has extremely high reactivity with aldehydes. If desired, the oil shale may be fractionally distilled and only a specific distillate may be used. Furthermore, for aldehyde 4L, the aldehyde donor used is the aldehyde used in the above-mentioned initial condensate or a compound similar to the aldehyde donor.

The above-mentioned resorcinol compound and an aldehyde or an aldehyde donor are condensed by a conventional method, if desired, phenol, alkylphenol, catechol, alkylcatechol, hydroquinone, alkylhydroquinone, pyrogallol, phloroglycine, ureamelamine, urea, benzoguanamine, Polymers such as toluene, xylene, coumarin, cyclohexanone, cashew oil, tannins, Shichirank, Dammer, rosin-stomach gin derivatives, petroleum 11 fat, methanol, ethanol, isopropanol, N-butanol, ethylene glycol, glycerin, etc. Adding glycol, furfuryl alcohol, etc.
Co-condensation or modification is also acceptable. Further, a carbonyl group-containing compound such as acetone and pulllactam may be added as a condensation regulator.

A third component may be added in addition to the above-mentioned initial condensate and the above-mentioned resorcinol resin. Such third components include natural rubber and its derivatives, 88R.

Synthetic rubbers such as NBR, CB, EPR, Vinyl Vyridine Inter-Lima, vinyl acetate resin, ethylene/vinyl acetate copolymer resin, acrylic resin, methacrylic resin, ethylene/acrylic acid ester copolymer resin, vinyl chloride resin, vinylidene chloride Resin, polystyrene, polyethylene, chlorinated polyethylene, polypropylene, chlorinated polypropylene, polyester resin, urethane resin, polyamide, epoxy resin, various synthetic resins such as butyral resin, polyacrylic salt, polyacrylamide, CMC1 methyl heptylose, hydroxy Ethyl cellulose, polyvinyl alcohol, sodium alginate, starch, starch derivatives,
Glue, gelatin, glue such as blood meal protein, gypsum,
Calcium carbonate, carbon black, wood flour, walnut flour,
Coconut powder, fillers such as wheat flour, pigments (dyes, flame retardants,
There are insect repellents, preservatives, anti-aging agents, ultraviolet absorbers, etc.

The mixing ratio of the above-mentioned initial condensate and resorcinol resin can be appropriately adjusted depending on the purpose of use, and is not necessarily limited to a uniform ratio. The properties of the adhesive obtained vary depending on the mixing ratio of the initial condensate and resorcinol resin, but if the mixing ratio of the initial condensate is large, it is recommended to add a hydrochloric acid, ammonium chloride, paraformaldehyde, etc. This adhesive becomes an adhesive that hardens at room temperature, and when used to bond plywood, it is easy to obtain water-resistant adhesion that passes plywood JAs Standard Class I, and the aldehyde that may be generated as an initial condensation product is absorbed by the resorcinol resin. As a result, the amount of free aldehyde is significantly reduced. On the other hand, when the mixing ratio of resorcinol resin is large, the initial condensate functions as a curing agent for the resorcinol resin, but the room temperature curability is lower and the pot life is longer than when paraformaldehyde is used as a curing agent. Although it is usually cured by heating, it cures at a lower temperature and in a shorter time than when hexamethylenetecilamine is used as a curing agent. When the mixing ratio of the primary condensate and the resorcinol resin is around 1:1, it is desirable to add an aldehyde or an aldehyde donor as a curing agent.

As described above, the adhesive mainly composed of a mixture of an area precondensate and a resorcinol resin obtained by the present invention compensates for the drawbacks of both, has an appropriate pot life, and is resistant to water, boiling, and weathering. This adhesive provides excellent adhesive properties for wood, fiber, paper,
It can be applied to bonding a wide range of organic and inorganic materials such as leather, plastic, metal-glass, ceramics, and concrete.

The following is an actual aaip for explaining the present invention more specifically.
Let's talk about this.

To 100 parts by weight of Example area eluate (urea content 75% by weight), 203 parts by weight of 37% by weight lumalin and 10 parts by weight of sodium hydroxide aqueous solution @/,j were added, and the mixture was non-volatile by heating at 70°C for 3 hours. min 41 J:/wt%, viscosity 4 coboise (Jjt'), Pf17. An initial condensate of $ is obtained.

As the resorcinol resin, DFK-/NB (commercially available alkyl resorcinol resin Ni Nagoya Yukagaku Kogyo Co., Ltd.) was used.

The above-mentioned initial condensate and DFK-/NB were mixed in the ratio shown in Table 1, and the mixture was used as an adhesive for plywood and laminated wood to evaluate its performance. The results are shown in Tables 3 and 8.

Table 1/, ! −j −/, ! Manufacture 3-ply plywood using the lauan wood veneer from ■. The manufacturing conditions are as follows.

Veneer moisture content 7~towt% Cold pressure 10#/dX/! Minute accumulation time: 1
The adhesiveness of the plywood manufactured as described above was tested according to the JAS Compatible Board Standard. The results are shown in Table 3.

As shown in Table E, the mixture At #Al of the precondensate and DFK-/NB is each AI alone.

Compared to 44, the gel time, that is, pot life is longer, but 4
11IA shows good adhesion even after boiling, but
In the case of the initial condensate alone, the ore adhesion force substantially disappears after repeated boiling. DFK-/NB alone A4
shows excellent boiling resistance in terms of adhesive strength, but the gel time is extremely short.

Manufacture laminated wood using Douglas fir wood. The manufacturing conditions are as follows.

Moisture content, r-to weight% adhesive application amount -, 20g/II+'pressure?
#/dXJjtX2#krz The adhesiveness of the laminated wood produced as described above was tested according to JIBK-4102. The results are shown in Table 8.

1fsI Cloth As shown in Table 8, &3, which is an initial condensate alone, has extremely poor water resistance and boiling resistance, but AI and AI with DFK-/N added to it have significantly higher water resistance and boiling resistance. It's improving.

Claims (1)

[Claims] Aldehyde or an aldehyde donor is added to the area eluate generated in the precision casting method that uses area as a fugitive substance and reacted to form an area initial condensate, and a resorcinol resin is added to the area initial condensate for bonding. A method for reusing the area used in precision casting, which is characterized by