CS238838B1 - A method of manufacturing encapsulated cartridges - Google Patents

Abstract

The invention solves a method of producing a material based on polyurethanes, in particular a microcellular slightly foamed polyurethane elastomer with a bulk density of 250 to 800 kg. m-3, for polishing and grinding brittle and hard materials. The advantage of the material prepared by the method according to the invention is high resistance to abrasion, optimal penetration hardness and ductility, which, with a high service life, allows polishing at higher pressures and speeds, and therefore shorter technological times. The invention can be implemented in enterprises where materials such as mirrors, eye lenses, monocrystalline elements, glass jewelry, ceramics are finely ground and polished.

Description

The invention relates to a process for the production of a polyurethane-based mass 11a. polishing and grinding of fragile and hard materials such as mirrors, single crystal elements, glasses, imitation jewelery, ceramics, but also some metal parts.

The currently used polishing tools for polishing flat and curved surfaces are prepared by impregnating textile materials with various pitches and waxes, or by applying thermoplastic polymers and natural resins to synthetic fibers or metal carriers. For example, for polishing rotationally symmetrical functional surfaces, the polishing mass was prepared by applying 1.0 to 50% by weight of butyl and methyl methacrylate and 90 to 50% by weight of asphalt on a metal support and subsequent heat treatment (cf. Aut. Certificate 133 072). However, the present optical polishing technique requires a very intensive polishing process with high pressures and speeds, where these materials do not meet the requirements of low lifetime and longer technological times.

One of the requirements for polishing materials is also high abrasion resistance. In particular, polyurethanes are characterized by high abrasion resistance, therefore, an attempt is made to prepare polishing compositions on this basis. Of the polyurethanes, a microcellular rigid polyurethane foam with a higher bulk density of 150 to 500 kg is used. m "·’, but it is very fragile and does not experience higher pressures.

The aforementioned drawbacks are eliminated by the process for producing a polyurethane-based mass for polishing and grinding brittle and hard materials according to the invention, which is carried out by preparing the mass from diisocyanates treated with a polyol component containing a linear bifunctional polyol and auxiliaries, in particular crosslinker, preferably water, in an amount of 0.04 to 0.4% by weight of a stabilizer in an amount of 0.01 to 2.5% by weight and a catalyst in an amount of 0.01 to 1% by weight, calculated on the polyol, at a reaction temperature of 15 to ^r 70 C, preferably 25 to 50 DEG C., with stirring and the prepared mixture is introduced into a mold naseparovanej formed as a foamed polyurethane elastomer with a microcellular structure is then shaped adjusting.

An advantage of the process for preparing the polishing material of the present invention is the production of a material with high abrasion resistance, toughness and optimum penetration hardness. The material thus prepared also has a long service life, which allows intensive polishing at higher pressures and speeds. Another important factor is the possibility of variability of the properties of the polishing material according to the requirements for polishing and fine grinding of different types of materials depending on the ratio of starting, main and auxiliary raw materials. Last but not least, it is possible to prepare a polishing material with built-in abrasive powder in a mass structure in an amount of 2.5 to 60% by weight.

The microcellular polyurethane composition can be prepared by a one-step and two-step process. In a one-step process, the polyurethane is prepared by mixing the crosslinking component with polyisocyanates, typically in the presence of reaction retarders, in an amount of, for example, 0.05% by weight of citric acid. In a two-step process, a polyurethane polishing compound is prepared by reacting a prepolymer having a content of 4.3-

17.5% by weight, preferably 6 to 15.6% by weight, of free NCO groups with a chain extender in the presence of excipients, in particular blowing agents, stabilizers, catalysts, fillers and the like. The mole ratio of the starting materials in the preparation of the prepolymer, i.e. the content of the free —NCO groups, decisively affects the properties of the polishing material, in particular the hardness, and taking into account 11a the polishing process and the type of polishing material.

The prepolymer is formed by a conventional procedure by reacting linear polyols with diisocyanates under stirring and at higher temperatures, typically 90 ° C, generally in the absence of catalyst in an inert nitrogen atmosphere for 0.5 to 2 hours. Polyols which may be used are, in particular, polyester polyols, for example polyethylene glycol adipate, polyethylene butylene glycol adipate, polybutylene adipate, and other polyether polyols, for example polypropylene glycol, polyethylene glycols and polycaprolactones. Among the diisocyanates, in particular, 4,4á-methanediphenyl diisocyanate, 1,5-naphthyl diisocyanate and toluene diisocyanate, and further hexamethylene diisocyanate, are suitable.

Suitable chain extenders include, in particular, monoethylene glycol, diethylene glycol, triethylene molecular glycols such as, for example, glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,6-hexanediol, other diamines such as ethylenediainine, tetramethylenediamine, diethylamine, and aminoalcohols, popanolamín.

Of the blowing agents, it is particularly advantageous to use water, which at the same time also acts as a chain extender, in an amount such that a final product having a bulk density of 200 to 800 kg is prepared. nm ³ , preferably 350 to 550 kg. m ³ . In addition to water, other blowing agents may be used, for example fluorochloro derivatives of methane and ethane.

The preparation of the cellular elastomer may be carried out even in the absence of a stabilizer, more preferably in terms of porosity and homogeneity of the cellular structure of the material is to use a foam stabilizer, in particular stabilizers with which a foam material with a plurality of open cells is formed. Such stabilizers are many silicones in an amount of 0.05 to 2.5% by weight, preferably 0.1 to 1% by weight.

Suitable catalysts are, in particular, tertiary amines such as triethanolamine, tributylamine, N, N-dimethylcyclohexylamine, triethylamine, triethylenediamine, tin organo compounds, e.g.

With the process according to the invention, it is possible in a simple manner to incorporate into the mass the necessary amounts and types of powder materials, up to a content of 60% by weight. Suitable polishing and abrasive materials include cerium oxide, zirconium oxide, silicon carbide and many others.

Example 1

For the preparation of the microcellular polyurethane elastomer, a prepolymer containing 14.7% by weight of the free-NCO groups prepared by reacting 1000 g of polyethylene glycol adipate with an acid number of 0.7 mg KOH / g, a hydroxyl number of 56 mg KOH / g and a molecular weight of 2000 g. mol ^-1 , with a water content below 0.02% by weight with 1000 grams of 4,4'-methanediphenyldiisocyanate at 90 ° C with stirring under nitrogen for 30 min.

000 g of the prepolyroer are intimately mixed with the crosslinking component obtained by mixing 284 g of 1,4-butanediol, 10 g of silicone stabilizer, 0.7 g of dimethylcyclohexylamine and 2 g of water, and the mixture is poured into a separated metal mold heated to 50 ° C. The start time of the reaction is 30 seconds, the reaction time is 60 seconds, the release time is 5 minutes. The prepared microcellular tough material has a bulk density of 445 kg. ni ³ , hardness 23 ° Sh (D).

Example 2

Following the procedure of Example 1, a prepolymer containing 11.4% by weight of free-NCO groups was prepared by reacting 1000 g of polyether polyol [hydroxyl number 55.5 mg KOH / g, water content 0.01% by weight, mol. weight 2 000 g. mol ¹ ) and 700 g of 4,4'-methanediphenyl diisocyanate. The thus prepared 1700 g prepolymer is intimately mixed with the crosslinking component prepared by mixing 190 g butanediol-1.4, 2.5 g silicone stabilizer, 0.35 g triethylamine-dibutyltin dilaurate activator in wt. a ratio of 10: 1 and 2.1 g of water blowing agent, the isocyanate index being 105. The characteristic times of polyurethane preparation are: start time 24 s, reaction time 50 s and demold time 4 min. A uniform solid and elastic cell mass is obtained with a density of 320 kg. m ³ and hardness 18,8 ^c Sh (Dj.

EXAMPLE 1 a d 3

By reacting 1000 g of polycaprolactone (hydroxyl value 56.5 mg KOH / g, acid number 0.2 mg KOH / g, water content below 0.01% by weight with 250 g hexamethylene diisocyanate, a prepolymer containing 6.7% by weight is prepared. Polyurethane is formed by mixing 1250 g of prepolymer with a mixture of 86 g of butanediol-1,4- and 0.4 g of water, with a start time of 75 s, a foam growth time of 180 s and a release time of 10 min. it is partially inhomogeneous, has a density of 600 kg m ³ and a hardness of 25,1 ° Sh (Dj.

Example 4

285 g of iron oxide in the form of a very fine powder are mixed into 1000 g of the prepolymer prepared according to the procedure of Example 1. Then the mixture is intensively mixed with a crosslinking component consisting of 142 g 1,4-butanediol, 4 g silicone stabilizer, 0.3 g N, N-dimethylcyclohexylamine activator and 0.8 g water. Start time is 30 s, growth time 180 s and release time 10 min. The cellular brown-colored polyurethane material has a very southern structure, an ohne weight of 660 kg. m ³ and hardness 35 ° Sh (D).

Example 5

650 g of zirconium oxide are mixed into 1000 g of the prepolymer prepared according to Example 2, and then intensively mixed with a crosslinking component consisting of 112 g of 1,4-butanediol, 5 g of silicone stabilizer, 0.3 g of N, N activator -dimethylcyclohexylamine with stannous octoate in a weight ratio of 10: 1 and 1.2 g of water. The light gray mass obtained is uniform in structure and has a density of 520 kg. ni ³ and hardness 27 ° Sh (Dj.

Example 6

Polyurethane is prepared by a one-step process by mixing a mixture of 1000 g of the polypropylene glycol specified in Example 2, 85 g of 1,4-butanediol, 0.4 g of water, 2 g of silicone stabilizer and 0.7 g of citric acid] with 250 g of hexamethylene diisocyanate. The start time is 15 seconds, the reaction time is 95 seconds and the release time is 15 minutes. The mass has a relatively uniform structure, a density of 520 kg. m-3 and hardness 21 ° Sh (Dj.

Claims (3)

238838 SUBJECT MATTER CLAIMS 1. A process for the production of polyurethane-based masses for polishing and grinding brittle and hard materials, characterized in that it is prepared from diisocyanates which are treated with a polyol component containing a linear bifunctional polyol and auxiliary substances, in particular crosslinking agents, blowing agents, preferably water, in an amount of 0.04 to 0.4% by weight, a stabilizer in an amount of 0.01 to 2.5% by weight and a catalyst in an amount of 0.01 to 1% by weight, calculated on a polyol, at a reaction temperature of 15% to 70 ° C, preferably 25 to 50 ° C and under stirring, and the prepared reaction mixture is introduced into the molded form and the foamed polyurethane elastomer with microcell structure formed in the mold is then shaped. 2. A process according to claim 1, characterized in that a prepolymer is initially prepared from the starting materials, which is subsequently worked up under stirring, preferably simultaneously with a crosslinker, blowing agent, activator and stabilizer. 3. A process according to claim 1, wherein the polyol component or prepolymer is added in an amount of 2.5 to 60% by weight. Severografia, n. P., Race 7, Mast Price 2,40 Kcs