RU2277553C2 - Composition for the elastic coating of the molds at manufacture of the production tools - Google Patents

Abstract

FIELD: construction industry; compositions for an elastic coating of the molds at manufacture of the production tools for construction and decorative works.

SUBSTANCE: the invention is pertaining to the field of manufacture of the elastic, in particular, the rubber-silicon technological fittings used in production by small series of geometrically-complex artistically-applied details, in the works at manufacture of the technical-decorative products and restoration works. The composition for manufacture of the elastic coating for molds used for manufacture of the technological fittings contains the high-molecular silicone rubber in amount of 2-35 mass %, the curing agent - up to 0.5 mass % and the organic solvent - the rest. The technical result of the invention is production of the composition ensuring the increase of the operational life of the elastic technological fittings and possibility of the multiple restoration of their form up to the operational state.

EFFECT: the invention allows to produce the composition ensuring the increase of the operational life of the elastic technological fittings and possibility of the multiple restoration of their form up to the operational state.

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Description

The invention relates to the field of manufacturing elastic, in particular rubber-silicone, tooling used for the production of small series of complex parts, arts and crafts, in works when performing technical and decorative products and restoration works.

One of the ways of manufacturing experimental parts of new developments in small batches seems to be casting them into silicone elastic forms from thermosetting compositions or special waxes.

A significant problem is the erosion of the mold surface under the action of various components of the casting compounds, while it is not possible to ensure long-term operation of the mold and to replicate high-quality castings.

Thus, the restoration of forms and increasing their working resource seems to be a necessary task.

Known compositions for forms, including an elastomer, an organic solvent and other components (Reference "Electroplating", under the editorship of Ginzburg A.M., M .: Metallurgy, 1987). However, such a composition has low mechanical strength and viscosity, which does not allow using it for our tasks.

Also known are compositions that include serial sealants with a relatively high intrinsic viscosity (due to the lack of solvent), which does not allow coating with a minimum thickness of the relief surface, because in thin layers do not provide the necessary strength and elasticity (“Adhesives and sealants”, edited by DA Kardyshev, M .: Chemistry, 1978).

Described (Schetz M. “Silicone rubber”. L .: Chemistry, 1975) inaccessible rubbers and composites, judging by the data presented, do not provide sufficient ratios of viscous flow properties with strength and elastic properties to achieve the task.

The same applies to silicone-based polymeric materials based on low molecular weight cold cured rubbers (Labutin A.L. Directory, M .: Chemistry, 1974, Synthetic Rubber, L .: Chemistry, 1976).

Closest to the claimed composition, the low-viscosity siloxane composition proposed in RU 2052475, 01/20/1996, including, parts by weight: liquid siloxane rubber with terminal silanol groups (SKTN-A, SKTN-V, SKTNF, SKTN-2F6) 100.0 ; ethyl silicate-40 30.0-80.0; Organotin catalyst (K-18, K-1) 3.0-12.0; alkyl (aryl) acetoxysilane 0.5-1.5. Alkyl (aryl) acetoxysilane-methylphenyl diacetoxysilane, methyl triacetoxysilane, dimethyldiacetoxysilane, diethyl diacetoxysilane with a vulcanizate strength of 3.5-8.0 MPa after 1-3 days of curing, with an adhesive strength of 0.05-0.8 kN / m.

This composition is used as heat-resistant and frost-resistant protective coatings, impregnating compositions, adhesive film materials. The technical result is determined by the use of anti-adhesive temporary coatings and is achieved through the use of alkyl (aryl) acetoxysilanes in the composition.

However, their presence just precludes the applicability of the composition proposed in the closest analogue for our purposes.

From table 1 of RU 2052475 it follows that the curing time of the composition from 1 to 3 days.

In the claimed solution, in the technological use of the composition, such curing conditions are not allowed, since The claimed composition is intended for applying it to the multidisciplinary multilevel surfaces of technological equipment. A long curing time will inevitably lead to spontaneous swelling of the composition from the upper points of the form down, its accumulation in these areas, i.e. irreversible distortion of the geometry of the form, a change in the surface pattern and other necessary parameters of a complex elastic form.

In addition, acetoxysilane does not provide uniform solidification of the silicone in thickness and the resulting monomer coating has an internal stress, which is unacceptable during the operation of the mold, because sharply reduces its resource.

Thus, the known composition does not provide the necessary wear resistance of the forms, their performance and the possibility of repeated restoration of the form, in addition, a long time of curing it (up to 3 days) on the surface does not meet the requirement of uniformity of application of the composition on complex profiles.

That is, the composition of RU 2052475 for the indicated purposes is not applicable.

The essence of the invention is to create a composition that provides an increase in the resource of flexible technological equipment and the possibility of multiple high-quality restoration of the form to a working state.

A composition for flexible tooling is proposed, including silicone high molecular weight rubber, a curing catalyst and an organic solvent at certain component ratios specified in the claims.

The technical result is achieved by the fact that the composition of the elastic coating forms in the manufacture of elastic technological equipment, including an elastomer and an organic solvent, as an elastomer high molecular weight silicone rubber and a curing catalyst in the following ratio, wt.%:

high molecular weight silicone rubber 2-35 curing catalyst up to 0.5 organic solvent rest

Data on the characteristics of the composition when using various quantitative ratios of the components are shown in table 1.

Property Composition Curing time, min Tensile strength, MPa Shore hardness, A Elongation at break Adhesion to the surface, peeling strength, kn / m Prototype SKTN - A 1-3 days 4.0-7.2 118-74 SKTN - B 3 days 5,4 98 SKTNF 3 days 5,0 --- 53 --- SKTN - 2F6 3 days 3,5 58

cont. table 1 1. High molecular weight rubber-SKTV - 2 wt.%., 20-30 1.7 30-35 300 > 0.45 catalyst (2 days) curing - 0.1 wt.%., (ethyl silicate 40 dibutyl diol tinolurinate acc. 3: 1) solvent - hexane - the rest 2. High molecular weight 30-40 2.0 30-35 300 > 0.5 rubber SKT-4 wt.%., (2 days) curing catalyst - 0.1 wt.%. (butyl silicate-40 - diazobutyltin diapronate according to 4: 1), solvent - heptane - the rest 3.High molecular weight 100-200 2,5 30-35 350 > 0.6 rubber SKTV-1 - 15 wt.%., (1 day) curing catalyst - 0.1 wt.%., (ethyl silicate-32 - dibutyltin dilaurate acc. 4: 1) solvent - heptane - the rest 4. High molecular weight 150-200 2,5 30-40 400 > 0.8 rubber-SKT - 20 wt.%., (2 days) catalyst curing - 0.4 wt.%. (ethyl silicate-40 - tin octoate acc. 7: 1) solvent - octane - the rest

cont. table 1 5. High molecular weight 200-300 2,8 30-40 420 > 0.8 rubber SKTV-35 wt.%., (1 day) catalyst curing - 0.1 wt.%., (ethyl silicate-32 - tin octoate acc. 10: 1) solvent - heptane - the rest 6. High molecular weight rubber SKTV - 6 wt.%., 50-60 2.6 35-45 400 > 1.0 (1 day) curing catalyst - 0.5 wt.%., (ethyl silicate-32 tin diethyl dicaprylate according to 6: 1), solvent - octane - the rest

The physical properties of the claimed composition, namely fluidity, can repeatedly eliminate caverns, the effects of erosion on the surface of the tool and other defects that arise during operation by repeated or partial application of the composition to the surface of the mold. The inventive composition well eliminates the resulting defects in shape, allows you to make the necessary refinement of the surface to the state required by the technical conditions.

The composition uses

silicone rubbers with a molecular weight of 200-500 thousand, with properties corresponding to the technical conditions

- SKTV, - TU 38.103675-89,

molecular weight - 200-500 thousand

mainly methyl methyl units (up to 1% methyl vinyl units) curing catalyst is ethyl silicate-40-dibutyl diol tin olurinate.

- SKT, -TU 38.103694-89,

molecular weight - 200-500 thousand

the curing catalyst is butyl silicate-40-diisobutyltin dicapronate.

- SKTV-1, TU 38.103675 - 89,

molecular weight - 200-500 thousand

curing catalyst - ethyl silicate-32-dibutyltin dilaurate.

Curing catalysts (grades K-1, K-68) are a mixture of alkyl silicates with tin salts in ratios from 1: 1 to 10: 1. The main generators of the formula

R ^' ₂ S _n (OCOR ^'' ) ₂ .

The general properties of curing catalysts are their ability to form vulcanizate over a wide time range.

Organic solvent. As a solvent, C ₅ -C ₉ hydrocarbons are preferred. The best results are obtained with hydrocarbons of a linear type or acyclic structure.

Due to the high adhesive properties of the claimed composition allows you to apply on the surface of the mold, if necessary, a uniform layer, including those with conductive properties. In combination with a finely divided filler, the composition has significantly greater elasticity than the closest analogue.

The inventive composition is made by mixing all the components using a mixer for 2-10 hours at a temperature of (20-35) ° C. In this case, the rubber is preliminarily swelled in an organic solvent. The composition thus prepared is applied to the model by dipping or using the hand method, dried at room temperature (20 ± 5) ° C for 1-24 hours, removed from the model and used as part of the equipment.

The properties of the claimed composition in comparison with the prototype and its main physical and mechanical characteristics are shown in table 2.

table 2 The properties Cure time Tensile strength, MPa Shore hardness, A Elongation at break The claimed composition 20-300 min 1.7-2.8 30-40 up to 420 Prototype 1-3 days 3,5-8,0 - 53-118

Table 2 summarizes the test results and shows that optimal properties can be obtained provided that the composition contains high molecular weight silicone rubber (2-35 wt.%.) And a curing catalyst (up to 0.5 wt.%.).

Analysis of all the data shows the following advantages of the claimed composition in comparison with the prototype:

- the inventive composition provides the formation of a solid monolithic coating on the model for the required time period without distortion of the application surface,

- technological equipment with this composition has an increased resource due to the use of high molecular weight silicone rubber,

- due to the physical properties of the composition (fluidity, adhesion), the mutual penetration of the applied layers by chemical affinity occurs with a silicone elastomer of the form,

- the possibility is achieved of repeatedly recovering undergoing surface erosion during the operation of technological equipment,

- as well as additional protection against erosion of the surface layer of the form by the poured compounds

- allows you to produce complex with small details of the product,

- ensures the efficiency of the entire technological process by increasing the resource of the form and the possibility of its repeated restoration.

Only the claimed combination of components in the given amounts allows to increase the working resource of elastic technological equipment and to provide the possibility of repeated restoration of the form to a working state.

Claims (1)

Composition for flexible coating of molds in the manufacture of tooling, containing high molecular weight silicone rubber, a curing catalyst and an organic solvent in the following ratio, wt.%: High molecular weight silicone rubber 2-35 Curing catalyst Up to 0.5 Organic solvent Rest