Goodnaturedly mixture

 

(57) Abstract:

The invention relates to goodnaturedly mixtures for the manufacture of foundry cores and molds. Goodnaturedly the mixture comprises (m h): 100 quartz sand, 1.5 to 2.5 alkaline polyphenolic resin and 25-30% by weight of the resin ester hardener. As a hardener mixture contains glycol acetates or mixtures thereof with-butyrolactone or propylene carbonate. The invention can be adjusted over a wide range of survivability and speed of hardening goodnaturedly mixtures. 14 table.

The invention relates to foundry, in particular to the core and molding goodnatured mixtures (CTS) for the manufacture of foundry cores and molds.

Known cold solidifying mixtures with synthetic resins carbamidefuran (for example, BS-40), phenol (for example, SF-3042) or peneloperainbow (for example, FF-1F) class, curing acid catalysts. Resins of these classes have a high toxicity. The content of free formaldehyde in the resin BS-40 reaches of 1.7% (when MPC=0.5 mg/m3), the content furisosogu alcohol - 40% or more of nitrogen - 12%. In the phenolic resin content of free phenol reaches 15% (when MPC=03 mg/what I cause the formation of metallized burns sieve porosity and gas pockets in the casting.

The possibility of regulating the survivability and hardening rate of such mixtures is very limited. It can only be done by changing the concentration of the catalyst or its content in the mixture.

In the foundry industry as a binder for the preparation of CTS often use phenol-formaldehyde resin, which depending on the conditions of their reception are divided into Novolac and rezol. Novolac resins get in an acidic environment and rezol - alkaline.

As the closest to the present invention prototype taken CTS on the basis of phenol-formaldehyde rezol resin RSF-3010. Resin is a product rezol polycondensation of phenol and formaldehyde in the presence of a synthesis catalyst is magnesium oxide (Handbook "Molding materials and technology mold" page 91, PL.46). The content of free phenol in the resin RSF-3010 no more than 15%, a free formaldehyde is less than 2%.

The composition of the CTS on the resin RSF-3010, wt.h.:

The quartz sand 100

Resin RSF-3010 2

Water p-p benzosulfimide

(BSC), the density of the 1.265 g/cm31,2

Survivability cm is s and technology mold"). The disadvantages of the CTS on the resin RSF-3010 (the prototype) are high toxicity due to high content of free phenol and formaldehyde, limited opportunities for regulation of survivability and hardening rate of tripping and reduce the strength and speed of hardening at low temperatures. In addition, phenol-formaldehyde resin similar to the resin RSF-3010 and CTS based on them lead to the formation of metallized burns and other defects in the castings.

According to the present invention as a binder in the composition goodnaturedly mixture is applied known rezol phenol-formaldehyde alkaline water-soluble resin, which represents a phenol-formaldehyde oligomer, translated due to excess alkali (sodium hydroxide or caustic soda) in the form of polifenoles. Binder and hardening the system on its basis by the English group Borden Chemical UK. This system was called Seth process. In the early 90-ies of the 20th century set the process has been widely used in Europe, USA, Japan. Now you start to use it and at the enterprises of the Russian Federation. The essence of the process is described, in particular, article C-J. Nybergh (firm OYLUX AB, Espoo, Finland) "Alphaset process and Eveno JSC "Uralkhimplast". She was awarded a trademark FSM-1.

According to the JSC “Uralkhimplast” THE 6-00-5751766-4-88 "of furan Resin and phenolic silenzione" resin FSM-1 represents the reaction product of diphenylpropane, phenol and formaldehyde, modified followin alcohol, ethylene glycol and silicone monomers. Rezol alkaline phenolic resins have a pH of 12.5-14; the content of free formaldehyde not more than 0.3%, and the free phenol is not more than 0.2%. Mass fraction of water in the resin up to 40%. Currently used for cooking CTS synthetic resin (phenol-formaldehyde, urea - and proliferance) have rn,5-8,4. They are all practically vodorastvorimyi.

The fundamental difference alkaline resins from other classes of synthetic resins used for the preparation of CTS, is that the first otverzhdajutsja ester reagents, and the second acid catalyst (H3RHO4benzosulfimide - BSC, n-toluensulfonate).

Due to the absence in the Russian market for alkaline ester resins hardeners set the process we found very limited application with a focus only on imported hardeners. In table. the AMI under different brand names for a set of process and providing mixtures of different size survivability. The composition of foreign hardeners unknown. Hardeners were tested in mixes on alkaline resin JSC “Uralkhimplast” brand FSM-1 in the following, wt.h.:

The quartz sand 100

Resin FSM-1 2,5

Hardener 0,75

Mode mixing on a laboratory blade mixer mixing the hardener with filler 1.5-2 min, then was injected resin and the mixture is stirred for 45 to 50 C. the strength of the mixtures were tested in compression after 20 min, 1 h, 3 h and 24 h of curing. The persistence of the mixtures was determined by the instrument design TSNIITMASH.

The table shows that different brands of foreign hardeners have different activity, allowing to obtain, depending on the production necessary survivability and speed of hardening mixtures.

The technical task of the present invention is goodnaturedly mixture comprising 100 wt.h. quartz sand, 1.5-2.5 wt.h. alkaline polyphenolic resin (or alkaline polifenoles) and 25-30% by weight of the resin ester hardener - glycol acetates, or mixtures thereof with butyrolactone in their mass ratio from 1:9 to 9:1, or a mixture thereof with propilenkarbonate hardening goodnaturedly mixtures.

For the preparation of CTS instead of quartz sand as a filler can be used, and other high strong refractory materials, such as granular Distin-sillimanite, chromite, zircon, corundum, and others. Because high strong refractory fillers have a higher density than quartz sand, binder content and advertiseda in the mixture must be adjusted in the direction of reducing them.

As a binder in the mixtures used alkaline polyphenolic resin (alkaline polifenoles), produced for the set of process under various trademarks, including resin, produced by JSC “Uralkhimplast” under the trademarks FSM, for example resin FSM-1, with which we have conducted basic tests.

Ester hardeners can be a glycol acetates (ACEG) in independent form or two hardeners, consisting of glycol acetates and one of the two cyclic ethers: -butyrolactone or propylene carbonate, regulatory survivability and speed of hardening mixtures depending on the specific production conditions or temperature of the surrounding air.

As one of the cyclic ethers proposed-butyrolactone when changing aspect] is 6 to 30 min, and the curing time is from 9 to 48 min while increasing the strength.

Other cyclic ether of the present invention is propylene carbonate. He is more active than butyrolactone. When changing the relation between ACEH and propylene carbonate in the range from 1:1 to 25:1 the persistence of the mixture increases from 2 to 20 minutes, and the curing time is from 4 to 32 minutes

When using ACEH in independent form of the persistence of the mixture can be increased to 40-60 min with a significant reduction of strength in the initial stages of hardening.

The invention is illustrated by the following examples. One of the main components of our proposed ester hardeners are the acetates of ethylene glycol. It is a mixture of di - and monoacetate of ethylene glycol. Getting glycol acetates consists in the synthesis of the product from acetic acid and ethylene glycol. Structural formulas diacetate and monoacetate of ethylene glycol:

Technology of production of acetates of ethylene glycol was developed with our participation. Currently, the industry produced 5 marks ACEH for utverjdena liquid XTC. They are different fractional composition - the ratio between di - and monoacylglycerols CTS from 5-6 min to 1.5-2.0 hours. Inbox us denote brands curing agents for liquid XTC and their composition are given in table.2.

In table.3 shows the properties of the CTS on the resin FSM-1 with 6 brands of ACEH. The composition of the test mixture, wt.h.:

The quartz sand 100

Resin FSM-1 2,5

Hardener, ACEH 0,75

From table.2 and 3 shows that with the increase of the brand hardener and a decrease in its content monoacetate of ethylene glycol survivability mixtures significantly increased, and strength properties in the initial stages of hardening slightly reduced, while the daily strength are aligned. In a production environment it is sometimes necessary to use a mixture with survivability 60 min or more. In this case, it can be used ACEH consisting of pure diacetate, ethylene glycol and practically do not contain monoacetate of ethylene glycol (provisionally designated brand OOM). Properties of this mixture are listed in table.3.

The properties of the mixtures are given in table.3, obtained at temperatures of 18-20C. To get the survivability of less than 25 min and accelerate the hardening of the mixture using one of ACEH cannot. However, the acetates of ethylene glycol can be used in independent form to reject the medium and high ambient temperatures. In relation to these conditions they meet foreign hardeners marks an-61 and H-30 (table.1).

However, at temperatures of +10-15C and below the durability of the mixtures increases, the rate of hardening is reduced and the strength of the fall. In the winter, for example, disclosure of core boxes and drawing models when used as hardeners, ACEH can be carried out not earlier than in 1,5-3 h, which in most cases is unacceptable for industrial practice.

To reduce robustness, but also for regulation in a wide range of survivability and hardening rate of CTS with alkaline phenolic resins, we propose to use cyclic esters, which on theoretical concepts should more actively compared to ACEH to cure CTS alkaline resins. According to our data, the most effective representative of a large group of cyclic esters for alkaline curing resins is butyrolactone. Get it by dehydrogenation of 1,4-butanediol followed by distillation. The issue butyrolactone is beyond 64-9-07-87, according to which the mass fraction of butyrolactone in the product not less than 99,0%, density 1,1266-1,1286 g/cm3.

Structural formula b is P CLASS="ptx2">

Another cyclic ether - propylene carbonate - is a full, cyclic ether of propylene glycol and carbonic acid. The structural formula of propylene carbonate

The basic substance content in the product is not less than 98%. Density 1,198 - 1,200 g/cm3(THE 2435-378-05742746-2001).

Test in equal conditions with the same mixture composition (wt.h.: silica sand - 100 resin FSM-1 - 2,5, hardener - 0,75) best quick foreign hardener EN-51-butyrolactone described BSM (fast overdyed for resin), showed that the hardener BSM on structural characteristics (at one and the same survivability) is significantly superior to the best foreign analogues (see table.4).

Apply-butyrolactone as a separate hardener is technically feasible, but economically it may be disadvantageous because of the relatively high cost of butyrolactone.

Two-component curing agent consisting of ACEH and-butyrolactone (BSM) at various ratios, allows a wide time interval to adjust the survivability and speed of hardening CTS while increasing strength. The hardening time of about 50% more survivability see what thatnot (BSM) for survivability, the time of hardening and strength of the mixtures are presented in table.5.

The composition of the mixture for testing was selected following, wt.h.:

The quartz sand 100

Alkaline phenolic resin FSM-1 2,0

Hardener variable composition 0,6

The tests were performed at temperatures of 18-20C. In the composition of the curing agent was changed ratio between ACEH and BSM in the range from 9:1 to 1:9 (wt.h.). Under the numbers 1 and 9 shows the properties of the blend at 100% ACEG (mixture 1) and 100% MSM (mix 9). In a mixture of 2, for example, when the ratio ACEH:BSM=9:1 hardener consisted of 90% ACEG and 10% MSM; in a mixture of 5 with a ratio of ACEH:BSM=1:1 hardener consisted of 50% ACEG and 50% MSM, etc.

In table.5 and subsequent tables 6-13 in the compositions ester hardeners used ACEH grade 3 CM, which is a mixture of mono - and diacetate of ethylene glycol. The content of monoacetate in this hardener is in the range of 22-26% by mass.

From table.5 shows that decreasing the ratio between ACEH and BSM (-butyrolactone) or increase in the content of the hardener composition BSM survivability of the mixture and the curing time is gradually reduced with a significant increase in strength at all stages of hardening. The lower the moderate magnitude survivability (not more than 30 minutes), and the upper limit of the ratio between ACEH and MSM should be limited to 1:9 with regard to more cost-butyrolactone (about 2 times) compared to ACEH, and also because the vitality and strength of the mixtures during the transition from a ratio of 1:9 to one-butyrolactone changed slightly. In everyday industrial practice it is preferable to use a two-component curing agent with a ratio within ACEH and MSM from 4:1 to 1:4.

For survivability, the curing time and initial strength of the mixture is substantially influenced by the temperature of the ambient air and source ingredients.

In table.6 and 7 shows the effect of temperature on the properties of mixtures with different hardeners.

In table.6 presents the properties of the mixtures at a temperature of 8-10C with two kinds of hardeners: two-component at a ratio of ACEH:BSM=1:1 and one - on-one ACEG.

In table.7 shows the effect of temperature on the durability and initial strength of the mixture (after an hour curing) at a ratio of the hardener, ACEH and BSM equal to 1:1.

With decreasing temperature, the survivability of the mixture increases sharply, and the initial strength fall. For a mixture with one of the ü slowly hardens and its use becomes impossible. In relation to these conditions, the use of two-component curing agent is mandatory.

Another representative of the complex cyclic ethers, is able to regulate the durability and speed of hardening CTS with the alkaline resin is propylene carbonate (FCT) - ester of propylene glycol and carbonic acid. In table.8 shows the properties of CTS on alkaline polyphenolic resin with two hardeners with different ratios of ACEH:FCT, changing in the range from 1:1 to 25:1 (mixture 1-8). In the same table properties on the same hardener, ACEH (mix 9).

The data table.8 shows that with increasing the ratio of ACEH:PCT survivability mixtures increases from 2 min (at a ratio of 1:1) to 20 min (at a ratio of 25:1).

From the comparison of the data of tables 5 and 8 shows that propylene carbonate compared with butyrolactone more actively affect the survivability and hardening time of the mixture at a lower its content in the composition of the hardener. When this strength properties unlike mixtures-butyrolactone changed slightly. In table.8 shows the properties of the mixtures at a temperature of 20C. At other temperatures with the same ratios between ACEH and the FCT ZnO limit 1:1, that ensures the survivability of the mixture equal to 2 minutes At a smaller ratio of the mixture becomes-low-tech. The upper limit of the ratio of ACEH:FCT limited us 25:1, in which the persistence of the mixture is quite acceptable for production purposes, and strength properties of the mixture is high enough. If necessary, increase survivability, you can use the hardener, ACEH in independent form (mix 9, PL.8). In addition, when the ratio is about 25:1 may be difficulties in the preparation of two-component curing agent due to the small quantities of propylene carbonate.

In table.9 and 10 shows the compositions and properties of the mixtures at the boundary and the average ratios between ACEH-butyrolactone (BSM), and table.11 and 12 composition and properties of the mixtures at the boundary and the average ratios between ACEH and propylene carbonate.

In table.13 shows three specific composition CTS with alkaline rezol resin brand FSM-1: at minimum binder content of 1.5 wt.h. (mixture 1), at an average grade of 2.0 wt.h. (mix 2) and with a maximum resin content of 2.5 wt.h. (mixture 3), with different hardeners and CTS prototype (mixture 5). A mixture of 4 contains ester hardener with the changing ratio between ACEH and>/P>From a consideration of the table.13 and 14, when the lower limit of the content of the binder (1.5 wt.h.) you can do CTS with satisfactory strength and technological properties when using high-quality enriched quartz sand. On an ordinary quartz sand with clay content up to 2% mixture with 1.5 wt.h. binders have relatively low strength and high asiaeast. With a further reduction of the content of the binder, even when using enriched quartz sand mixture be-low-tech. The upper limit on the content of alkaline phenolic resin should be limited to 2.5 wt.h., since the mechanical properties of CTS with 2 and 2.5 wt.h. differ a little, and the increase in the content of the binder increases the cost of the mixture and increases its attornet.

The optimum content of alkaline phenolic resin in the mixture should be considered as 1.8 to 2.2 wt.h.

Comparison of properties of mixtures 2 and 4 on the resin FSM-1 with a mixture of the prototype (5) shows that the properties of the first two mixes stand out from the properties of the mixtures according to the prototype, both in mechanical properties and control survivability and speed of hardening.

Method of preparation of two-component ester OTES cyclic ethers: -butyrolactone (BSM) or propylene carbonate in the above the invention the ratios (wt.h.) under mechanical stirring and at ambient temperature.

Using esters of glycol acetates and two representatives of cyclic esters: -butyrolactone and propylene carbonate for the first time in the Russian Federation proposed gamma domestic one - and two-component curing agents for CTS on alkaline polyphenolic resins, allowing to regulate in a wide time interval survivability (from 5-6 min to 60 min) and the rate of hardening mixtures.

Proposed hardeners are not inferior and in some respects superior to the best foreign analogues.

CTS alkaline resins developed but the present invention hardeners have been wide production tested and implemented at several plants, including JSC “Cherepovets casting and mechanical plant”, Kolomna LLC Metallicas” and other enterprises.

Techno-economic advantages of the invention compared with the known CHC on synthetic resins are as follows:

- improving the quality and surface finish of castings of iron and steel, including cast manganese steels;

- virtually eliminated the formation of metallized burns and "punching";

several times reduces the number of defects and b is the remaining resin free of phenol and formaldehyde (dozens of times) are significantly improved sanitary and hygienic working conditions, and environmental conditions in foundries.

Goodnaturedly mixture comprising 100 wt.h. quartz sand, 1.5-2.5 wt.h. alkaline polyphenolic resin and 25-30% by weight of the resin ester hardener - glycol acetates or mixtures thereof with-butyrolactone in their mass ratio from 1:9 to 9:1, or a mixture thereof with propylene carbonate at a mass ratio of from 1:1 to 25:1.

 

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