CS252379B1 - Abrasive polyurethane material and method of production - Google Patents

Abstract

The subject of the solution is an abrasive polyurethane compound for surface treatment of hard, especially metal materials, which consists of 80 to 40 wt. % polyurethane foam elastomer type hardness "Shore A" 20 to 45 bulk density 200 to 500 kg/m3 and 20 to 60 wt. % solid abrasive. This compound is produced by a one-stage reaction of a polyurethane prepolymer based on a linear polyether polyol terminated partly with primary hydroxyl groups, containing 2.3 to 15.5 wt. % free —-NCO groups, with a low molecular weight diol or diamine in the presence of 0.05 to 1.3 wt. part of an activator, 0.01 to 1.2 wt. part of a silicone stabilizer, 0.05 to 0.7 wt. part of a blowing agent and 5 to 120 wt. parts of solid abrasive, calculated per 100 parts by weight of prepolymer, at a temperature of 20 to 80 °C, while the batch of individual components and the temperature of the prepolymer are selected so that the demolding time is in the range of 3 to 10 minutes.

Description

252379

BACKGROUND OF THE INVENTION The present invention relates to a polyurethane grinding material for surface treatment of hard, especially metal, materials and to a process for its production.

In the production of replaceable metal punch pads, sintered cartridges, ceramics, or others, it is necessary to cover the edges with gray edges.

By providing a radius on the cutting edge in the range of 0.02 to 0.07 mm, the functional properties are considerably improved and the cutting edge strength is increased. Rounding round edges can be accomplished in a number of ways, of which rounding on elastic rolls filled with solid abrasives is the most advantageous in terms of rounding uniformity, high productivity and low manufacturing costs. The properties of the elastic disc, such as strength, toughness, elasticity, but also the structure of the material, the other handle, the type and size of the particles used by the abrasive material in a decisive way influence the quality and technological mode of processing. Many materials, mostly from the range of macro-molecular plastics they are not particularly suitable for the preparation of discs especially because of the difficulty in incorporating solid abrasive grinding in a high concentration ratio; in some parameters of physico-mechanical properties, for example: low abrasion resistance, weak abrasive bonding to the mass and the like. Such materials are, for example: rubber, rubber, polyolefins or polyamides.

The use of a polyurethane foam or a reaction product of polyvinyl alcohol with formaldehyde (DOS 3114 001) is known for the preparation of the polishing compound. The foam is soft and slightly porous, strong hydrophilic and compressible, useful, for example, for nail polishing, polishing and tooth cleaning, but the surface treatment of metal materials is unsuitable.

Other authors (U.S. Pat. No. 4,128,972) have produced a polyurethane or epoxy resin abrasive polishing wheel of an unfoamed bulk weight of an elastomeric binder. 1 g / cm3, Sh (A) hardness from 50 to 60. The polishing surface of the already produced molding hardness in the range of 85 to 95 Shore A. Such a prepared roll is antistatic, non-tear, but not suitable for rounding due to its higher hardness cutting edges, because of insufficient machining, which requires multiple repetitions of operation associated with increased operating costs.

SUMMARY OF THE INVENTION The subject of the present invention is an abrasive polyurethane composition for surface treatment of hard, in particular metal materials, characterized in that it comprises 80 to 40% by weight, preferably 65 to 45% by weight, of polyurethane foamed elastomeric material. Shore A '20 to 45 and a bulk density of 200 to 500 kg / m3 and 20 to 60% by weight, preferably 35 to 55% / weight. a solid abrasive incorporated and evenly distributed in the polyurethane.

According to the present invention, the process for producing the abrasive polyurethane mass is such that the polyethanes prepolymer with a content of 2.3 to 15.5 wt.%, Preferably 4.1 to 12.5 wt. the free NCO groups are derived from a linear polyetherpolyol terminated by primary hydroxyl groups, the proportion of primary hydroxyl groups being max. is reacted in one step with a low molecular weight diol or diamine, preferably 1,4-butanediol in the presence of 0.05 to 1.3 wt. % of a tertiary amine activator, optionally in a mixture with organotin compounds of a weight ratio of 10: 1, 0.01 to 1.2 wt. of a diol silicone stabilizer, 0.05 to 0.7 wt. part of the blowing agent and 5 to 120 wt. part of a solid abrasive, calculated at 100 wt. of the prepolymer, at a temperature of 20 to 80 ° C, preferably at 35 to 55 ° C, with the charge of the individual components and the temperature of the prepolymer being chosen such that the defrosting time is in the range of 3 to 10 minutes. The advantage of the surface treatment of metal materials on polyurethane discs is that uniform and high-quality rounding of the gray edges is achieved, the working environment is improved and production costs are reduced with high productivity. The abrasive polyurethane material has excellent physico-mechanical properties, in particular optimum penetration hardness, strength, toughness, high resistance to vera and hence high durability, further suitable bubble-like structure with large number of open cells with a size of max. 1 mm. evenly bonded, while its incorporation into polyurethane material is not particularly demanding in terms of technology and labor.

Another important factor is the possibility of the properties of the abrasive material being attributable to the type of metal material being processed, which is achieved by selecting the type and the relative weight ratio of the starting materials, but notably the degree of foaming and the molar ratio of the diolocyanate diol, and then the abrasive and the other. , the grain size and distribution.

Generally, the cellular abrasive polyurethane composition is prepared by a two-stage pre-polymeric process. In the first stage, the prepolymer prepares a linear polyol with a diisocyanate and a content of 2.3 to 15% by weight. preferably 4.1 to 12.5% by weight of the free NCO groups which, in the second stage, by reaction with a low molecular weight diol or diamine in the presence of abrasives and auxiliaries, in particular an activator, a stabilizer, a blowing agent, and possibly further forms final product. A preferred process of preparation is such that in the polyurethane prepolymer a solid abrasive is first dispersed and then the crosslinking component obtained by mixing a low molecular weight diol or diamine with an activator, stabilizer and blowing agent is optionally added to the auxiliary substances. The system thus formed is intensively homogenized generally for 5 to 35 seconds and then poured into a pre-heated, pre-heated metal mold. The actual polyaddition reaction takes place in the mold to form the polyurethane, which is generally within 3 min. terminated at about 5-10 min. maybe a molded out mold. The shape of the molding is given by the mold used and depends on the kind of machine tool. The mass is generally prepared in the form of a sponge, e.g. 300 to 600 mm in diameter and 30 to 60 mm in diameter.

The prepolymer raw materials are polyols and diisocyanates. Of linear divalent polyols of mol. Weights of 1000 to 3000 are adipic acid-ethylene glycol-based polyester polyols, optionally other glycols, polyether polyols obtained by propoxylation of propylene glycol glycerin or trimethylolpropane, optionally followed by ethylene oxide addition, polyethylene glycols, polycaprolactone, polytetrahydrofuran and the like. Particularly advantageous in terms of reactivity is the use of polyetherpolyols terminated at least in part by primary hydroxyl groups. Suitable diisocyanates are, in particular, 4,4'-methanediphenyl diisocyanate (MDI), 1,4-naphthyldiisocyanate (NDIj, but also toluene diisocyanate and hexamethylene diisocyanate. The preparation of the prepolymer is generally carried out in the absence of a catalyst in an inert atmosphere of 70 to 100 ° C for 0.5 to 2 hours Low molecular weight diols and diamines are used as chain extenders and their charge is calculated from the NCO content of the prepolymer, ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,4 butanediol, 1,3-butanediol, 1,6-hexanediol, followed by ethyl diamine, butylenediamine, hexamethylenediamine, but also ethanolamine, or diethanolamine.

Suitable polyaddition polyurethane reaction catalysts tertiary amines, such as: triethylamine, triethylenediamine, N, N-dimethylcycloohexylamine, 1,4-dimethylpiperazine, and others, optionally in combination with organo-compoundamicin, e.g., stannous octoate, dibutyltin dilaurate . The preparation of cellular polyurethane can also be carried out without a stabilizer, more preferably a stabilizer, in particular a cell opening stabilizer, e.g. Tegostab B4113, Tegostab B1605, is used for the homogeneity and porosity of the cellular structure. freon-11, freon-12. The blowing agent composition determines the bulk density of the mass and hence its physico-mechanical properties, generally for a given purpose it ranges from 600 to 1200 kg / m 3.

As solid abrasives, many, in particular, inorganic materials such as carboxy silicon, boron carbide, iron oxide, oxidic acid, pezum and the like can be used. about particle size distribution. The handle, type and size of the abrasive is chosen according to the requirements of the laid material and its content in the mass is usually 5 to 140% by weight. calculated on polyurethane

A prepolymer having a content of 7.0% by weight is used to prepare the polyurethane grinding wheel. free NCO groups prepared by reaction of 5000 g of polyester polyol SlovapropTMP-48 (hydroxyl number of 48 mg KOH / g, primary OH content of 60% by weight, acid value of 0.1 mg KOH / g, water content 0.01% by weight, viscosity at 25 ° C 1.7 Pasja 2000 g 4,4'-methanediphenyl diisocyanate (Desmodur 44 j with stirring at 90 ° C for 45 min. 2,500 g of carbide silicon is dispersed in 2,400 g prepolymer with 45 ° C) a grain size of 100 to 125 µm, and a crosslinking component is added consisting of 157 g of 1,4-butanediol, 4 g of Ν, Ν-dimethylcyclohexyl amine, 2 g of Tegostab B4113 and 4.5 g of water. The starting time of the reaction is 40 s, the reaction time is 2 min and the molding time is 7 min. The prepared cell structure abrasive has a bulk density of 1050 kg / m 3, a hardness of 40 ° Sh (A) and a abrasive content 50 wt.

The disc-shaped abrasive with an external diameter of 400 mm, an inner diameter of 210 min and a crest of 40 mm is used to coat the edged edges of the SNMM 120 408 sintered carbide blades. A curvature of the cutting edge of 0.03 mm is achieved with a rounding time of 3 minutes, the life of the coil is 60,000 pieces. Example 2

The prepolymer is prepared by reacting 2,000 gpolypolyol adipic acid and ethylene glycol (Desmophen 2000, hydroxyl number 56 mg KOH / g, acidity value 1.0 mgKOH / g, molar weight 2000 g mol ”1, water contents 0, 55% C) with 800 gnaphthyl diisocyanate at 100 ° C for 1 hour. In 2,300 g of a prepolymer having a content of 8.4% by weight. 2,000 g of boron carbide (20-30 µm) were dispersed at 50 ° C at 1.5 ° C and 1.5 g of a stannous triethylamine mixture was added after addition of a crosslinking component consisting of 230 g of 1,6-hexanediol; in a ratio of 10: 1 by weight) and 5.1 g of water, this mixture is substantial and intensively homogenized 20 is poured into the separated mold. The start time of the reaction is 30 s, the reaction time is 60 s and the stripping time is 4 min. The abrasive material has a volume weight of 950 kg / m 3, a hardness of 35 ° Sh (also a content of abrasive of 44% by weight on the lapping

Claims (2)

252379 machines are obtained with SNMM 120 408 sintered carbide inserts, 0.02 mm rounded edge, 4 min rounding time, and 45,000 plate lifetime. EXAMPLE 3 By the procedure of Example 1, a prepolymer was prepared by reacting 4000 g of polyether polyol (hydroxyl number of 52 mg KOH / g, based on primary OH groups of 80% by weight, 0.05 mg KOH / s viscosity, viscosity at 50%). 25 ° C 1.4 Pas) and 1300 g 4,4'-methanediphenyldiisocyanate. In a 2,500 g prepolymer of 5.3 wt. 2,600 g of ferric oxide (70 to 80 μπ) were dispersed at 40 ° C at a temperature of 40 ° C and then a crosslinking component composed of 83.2 g of ethanolamine, 2.3 DabcaLV 33, 4 g of Tegostab B was added at once. 1 603 by 4.2 g of water. The mixture is immediately homogenized thoroughly, the reaction times being: start time 25 s, reaction time 50 with release time 2 min. The grit mass of the uniform cell structure has a bulk density of 1020 kg / m 3, hardness 40 ° Sh (A) and 50% wt. On this mass, a rounding of 0.035 mm was achieved with SNMM 120 408 pads, and a rounding time of 3 min and a lifetime of 65,000 plates. OBJECT An abrasive polyurethane mass for surface treatment of hard, non-metallic materials, characterized in that it consists of 80 to 40% by weight, preferably 65 to 45% by weight, of polyurethane foam elastomeric material Shore A 20 to 45 and 20 to 60% by weight, preferably 35 to 55% by weight. a solid abrasive incorporated and evenly distributed in the polyurethane. 2. A process for producing a polyurethane abrasive according to claim 1, wherein the polyurethane prepolymer having a content of 2.3 to 15.5% by weight, preferably 4.1 to 12.5% by weight. free-NCO groups on the base of the linear polyetherpolyol terminated by primary hydroxyl groups, the primary hydroxyl groups being max. 85% by weight, reacted in one step with a low molecular weight diol or a diamine, preferably 1,4-Bu; tndiol in the presence of 0.05 to 1.3 weight percent tertiary amine activator, optionally in admixture with a 10: 1, 0.01 to 1.2 wt% organotin compound; of a silicone stabilizer, 0.05 to 0.7 wt. part of the blowing agent and 5 to 120 wt. part of a solid abrasive, calculated at 100 wt. at a temperature of 20 to 80 ° C, preferably at 35 to 55 ° C, the batch of individual components and the temperature of the prepolymer being selected such that the defrosting time is between 3 and 5 minutes. Ssvsrografla, n. P., Plant 7, Most Cina 3.40 Xls