CS242544B1 - A method of producing polishing material with increased hardness - Google Patents

Abstract

The solution is a method of producing a polishing compound with increased hardness for surface treatment and polishing of brittle and hard materials based on polyurethanes. The essence of the solution lies in the fact that a trimerization catalyst comprising alkaline and/or phenolic and/or onium compounds is added to the system in an amount of 0.01 to 2.5 percent by weight, calculated on the starting raw materials at a reaction temperature of 15 to 90 °C, and the resulting polyurethane-isocyanurate elastomer of the cellular structure is then shaped.

Description

242544 3 4

BACKGROUND OF THE INVENTION The present invention relates to a process for the production of polishing materials with increased hardness for surface treatment and polishing of brittle and hard materials based on polyurethanes. Nowadays, high-intensity sposoboptical polishing is carried out on high-performance machines with higher turns and pressures, as a matter of course in proportionally increased demands and demands on the properties and lifetime of the laying masses. For this high-intensity polishing process, many polishing compositions used so far, e.g., materials prepared by impregnating fabrics with various smoky and waxes, or by applying thermoplastic polymers and natural synthetic fiber resins, or metal carriers, are poorly suitable. prepared by depositing mixtures of acrylates and asphalt on a metal support with subsequent heat treatment (No. 133,072).

These materials are not particularly suited to the low lifetime and long polishing times. The high abrasion resistance is characterized in particular by polyurethanes, but also by certain types such as, for example, hard polyurethane foam with a bulk density of 300 to 750 kg. m-3 is a significant brittle and slightly foamed polyurethane elastomer is relatively small with a hardness of 10 to 17 ° Sh (D) CS No. 238 838.

The hardness of the foamed polyurethane elastomer depends on the bulk density, but it increases slightly with the increasing molar ratio of the diisocyanate to the polyol, or the use of a triple chain extender. More significantly, the hardness is increased by the use of a filler in the range of 20 to 60% by weight, but the filler material is not suitable for many applications. It has been found that the hardness of the polyurethane elastomer is greatly enhanced by modifying the polyurethane with isocyanurate rings, i.e. preparing the polyurethane-isocyanate elastomer.

SUMMARY OF THE INVENTION The present invention relates to a process for the preparation of a polishing composition with a hardness base based on polyurethanes prepared by reacting a polyurethane prepolymer having a content of from 4.3 to 20% by weight, preferably from 8.5 to 17% by weight. free NCO groups, and a low molecular weight diol and / or diamine in the presence of excipients, in particular an activator, a stabilizer, a blowing agent, and a polishing agent, such that a trimerization catalyst is added to the reaction system, including the alkali and / or phenolic and / or anionic compounds in an amount of 0.01 to 2.5% by weight, preferably 0.02 to 1.2% by weight, of the calculated feedstock at a reaction temperature of 15 to 90 ° C and the resulting polyurethane-isocyanate elastomer of the cell structure is then shaped shapes. An advantage of the polishing process of the present invention is the production of a high-intensity, high-pressure and high-speed polishing method which, while retaining the other excellent properties of the polyurethane elastomer, particularly high abrasion resistance, thus of strength, elasticity and dimensional stability in the temperature range of -20 to - (- 80 ° C> has a suitable microcell structure with open-pores up to 1 mm in size and isocyanate-indexed in the range of 15-750 high hardness in the range of 15 to 7 depending on isocyanurate content) up to 60 ° Sh (D).

Another important factor is the possibility of the properties of the polishing material being made available by the polishing requirements of various materials by varying the feedstock and the type of starting materials, especially the molar ratios of the main and auxiliary reaction raw materials. Last but not least, it is possible to prepare a polishing compound with a filler in an amount of 50% by weight.

Generally, the microcell polyurethane elastomer is prepared by a two-stage pre-polymeric process by reacting a linear polyol-diisocyanate prepolymer with a content of 4.3 to 20% by weight, preferably 8.5 to 17% by weight. free chain-extending NCO groups in the presence of additional excipients, in particular a discharger, an activator, a stabilizer, and others at a temperature of 15 to 90 ° C.

After the homogenization of the reactants is intensified, the reaction mixture is poured into the unsaturated metal form, resulting in a polyaddition and trimerization reaction of the polymeric polyurethane, whereby the molding time of the molding is generally not longer than 10 min. The molar ratio of the polyol to the diisocyanate and the crosslinker feed affects the polishing properties, in particular the hardness, strength and structure, and is chosen taking into account the type of polished material and the process of polishing and equipment.

Polyol and diisocyanates are the raw materials for the preparation of the polyurethane prepolymer. Voranol P 2000), propoxylated trimethylolpropane (Slovaprop TMP-56, SlovapropTMP-48), followed by polyethylene glycols (polyethylene glycol-1500, polyethylene glycol-4000), polycaprolactone (Niax 2025), polytetrahydrofuran and the like. Suitable diisocyanates include 4,4'-methanediphenyl diisocyanate (Desmodur 44) and 1,5-naphthyldiisocyanate, followed by toluene diisocyanate hexamethylene diisocyanate. The reaction is generally carried out without the presence of a catalyst at 90 ° C in an inert nitrogen atmosphere under stirring for 0.5 to 2 hours.

Molecular glycols, diamines and amino-alcohols such as monoethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butane- are used as chain extenders. diol, 1,6-hexanediol, ethylenediarin, hexamethylenediamine, tetramethylenediamine, ethanolamine, diethanolamine, propanolamine and the like, but also from a number of aromatics, e.g. diphenylmethanediamine. The chain extender considerably influences the hardness of the polyurethane product, by reducing its feed equivalent to the detriment of the polyadditional urethane reaction, the trimerization reaction of the NCO group takes place to form isocyanurate rings, thereby increasing molecular weight and cross-linking the polyurethane macromolecules .

The degree of cross-linking, and thus the isocyanurate content, is given by the isocyanate index value of 150 to 750 for the material, the isocyanate index 100 being the theoretical prepolymer for reaction with the chain extender and the chain extender. with chain and water extender. As a rule, with increasing isocyanate index, the hardness of the mass increases.

In the preparation of the slightly foamed polyurethane-isocyanurate elastomer, three types of reactions take place simultaneously, which must be well-balanced to achieve the desired properties of the polyurethane. The NCO group of the prepolymer reacts with the chain extender, the blowing agent, and the trimer to the isocyanurate rings, and their mutual relationship is determined by the composition and concentration of the individual activators of the catalyst system used.

Suitable catalysts for the polyaddition polyurethane reactions as well as for the reaction reaction are in particular tertiary amines such as triethylenediamine, N, N-dimethylcyclohexylamine, triethylamine, triethanolamine, 1,4-dimethylpiperazine, optionally in combination with organo tin compounds, e.g. stannous octoate, dibutyltin dilaurate.

Suitable trimerization catalysts are, in particular, potassium hydroxide, octane potassium, 2,4,6-tris (dimethylaminomethylphenol, organic ionic hydroxides such as tetra-methylammonium hydroxide, etc.). demanding, requires great theoretical knowledge and is usually determined experimentally, taking into account, in particular, the pre-polymer used, characterized by the content of the tracer-dependent NCO groups and the properties of the final product.

In addition to activators, blowing agents, in particular water, freon-11, freon-12, are also used as auxiliaries in such a concentration to produce a final product having a bulk density of 200 to 800 kg. m ~ 3, preferably 350 to 550 kg. m-3. The preparation of the cellular polyurethane can be carried out even in the absence of a stabilizer, more preferably homogeneity and the porosity of the cellular structure is stabilizer, in particular a pore stabilizer, e.g. Tego-stab B 1605, Tegostab B 4113 at the end of 0.02 to 1.5% by weight .

The process for preparing the polishing material allows the preparation of a material filled with a solid abrasive and a polishing agent, e.g., a silica crucible, boron carbide, cerium oxide, ferric oxide, pumice, etc., up to 50% by weight. Example 1

A 14.7 wt.% Prepolymer is used to prepare the microcell polyurethane isocyanurate elastomer. free NCO groups prepared by reaction of 1000 gp polyether polyol Slovaprop TMP-56 (hydroxyl number 55.7 mg KOH / g, acid number 0.05 mg KOH / g, water content 0.02%, viscosity at 25 ° C 6. Passing 1000 g of 4,4 ' -methanediphenyl diisocyanate (MDI) with stirring at 90 [deg.] C. under a nitrogen atmosphere for 30 min Add a crosslinking component containing 1,4-butanediol to the 1000 g of prepolymer in the amount indicated in the table below, 1.5 g of Tegostab B gilicon stabilizer 4113.1 g of water, 0.4 g of N, N-dimethylcyclohexylamine, 0.1 g of stannous octoate and 0.3 g of potassium acetate, vigorously stirring the mixture. it is heated to a temperature of 60 ° C.

The start time of the reaction is 25 s, the growth time is 60 s and the release time is 4 min. The hardened mass of the microcell structure has a bulk density of 350 kg / m3, while the hardness of the mass with the isocyanate index is as follows:

Experiment 1 2 3 4 5 6 7 butanediol-1,4 (g) 152 73 47 35 26 19 17 isocyanate index 100 200 300 400 500 600 700 hardness [° Sh (D) j 15 18 30 35 38 40 41

Claims (3)

242544 7 Example 2 A pre-polymer containing 17.9% by weight of free -NCO groups is prepared by the procedure of Example 1 by reacting 1000 g of polyester polyol Desmophen 2000 (hydroxyl number 55.5 mg KOH / g, acid number 0.6 mgKOH / g) , a water content of 0.03% by weight, a temperature of 55 ° C) and 1000 g of 1,5-naphthyldiisocyanate. The polyurethane elastomer is formed by reacting 1000 g of the prepolymer and the crosslinking component obtained by mixing 44 g of 1,4-butadiene (corresponding to the isocyanate index 400), 0.7 g of water, 0.6 g of triethylene. with an increased polyurethane hardness by reacting the polyurethane prepolymer with a content of 4.3 to 20% by weight, preferably 8.5 to 17% by weight. the free NCO groups and the low molecular diol and / or diamine the presence of excipients, notably the activator, the stabilizer, the blowing agent and the polishing agent, lndiamine and 1.2 g of 2,4,6-tris (dimethylamino-methyl) phenol. The mass has a regular structure with open cells and at a volume weight of 560 kg / m 3 has a hardness of 48 ° Sh (D). 3. Into the prepolymer prepared according to Example 2, 500 g of ferric oxide of 10 + 2 μΐη is mixed and allowed to react with the crosslinking component prepared according to Example 2. The cellular polyurethane elastomer has a bulk density of 680 kg / m @ 3 and hardness 60 ° Sh (D). characterized in that a trimerization catalyst comprising alkali and / or phenolic and / or anionic compounds in an amount of 0.01 to 2.5% by weight, preferably 0.03 to 1.2 ° C, is added to the reaction system. % by weight, calculated on the starting materials at a reaction temperature of 15 to 90 ° C. Severograíla, n. P., Plant 7, Most Price 2.40 KČS