RU2295553C1 - Anti-adhesion cover - Google Patents

Abstract

FIELD: special covers.

SUBSTANCE: invention relates to anti-adhesion covers used for prevention of sticking polymerized masses to working surface of form-forming metallic or plastic equipments. Invention proposes the following variant of cover for improving exploitation indices of anti-adhesion covers that comprises priming and bilayer covering layers based on organosilicon compounds. The priming layer is made on the composition base comprising the following components, wt.-%: dimethylsiloxane, 10-20; hardening agent, 1-2, and organic solvent, the balance. Covering layer is made in the following ratio of components in compositions, wt.-%: for the first layer: heterosiloxane, 20-40; hardening catalyst, 0.8-1.6, and organic solvent, the balance; for the second layer: "TSIATIM", 5-20 and organic solvent, 80-95.

EFFECT: improved and valuable properties of cover.

1 tbl, 3 ex

Description

The invention relates to the field of chemical technology, in particular to release coatings to prevent adhesion of the polymerized masses to the working surfaces of the forming metal or plastic tooling.

Organosilicon compounds, in particular polysiloxanes, are widely used as the basis for compositions for applying release adhesion coatings.

Known release coating RF patent No. 2034887 (publ. 05/10/97, BI No. 13), including the primer and coating layers based on organosilicon compounds using a solvent.

The disadvantages of the described analogue include the rather high adhesive properties of the coating and the inability to reuse the equipment.

As a prototype claimed release coating patent of the Russian Federation No. 2122561 (publ. 11/27/98, BI No. 33), comprising a primer and a two-layer coating layer based on organosilicon compounds, using a solvent in the compositions, while the primer layer is based on the composition, having the following composition, parts by weight:

Methyltriacetoxylan 0.85-1.90 Dimethyldiacetoxysilane 0.05-0.30 Solvent 98-99,

and the coverslip is made in the following ratio of components in the compositions, parts by weight:

For the first layer:

Polyorganoxylan 5-10 Organic solvent 90-95

For the second layer:

Polymethylmetallosiloxane or a mixture of polyorganosiloxane with polymethylmetallosilocane 5-10 Organic solvent 90-95

The disadvantages of the described composition include high adhesive indicators in relation to composite and nitro-containing materials.

The technical task of the invention is the creation of release coatings with improved performance properties.

The technical task is solved by the proposed composition of the release coating, which includes a primer and a two-layer coating layer based on organosilicon compounds, while the primer layer is based on a composition having the following composition, wt.%:

Dimethylsiloxane 10-20 Hardener 1-2 Organic solvent rest,

and the coating layer is made in the following ratio of components in the compositions, wt.%:

For the first layer:

Heterosiloxane 20-0 Curing catalyst 0.8-1.6 Organic solvent rest

For the second layer:

TSATIM lubricant 5-20 Organic solvent 80-95.

The technological process of forming products involves applying anti-adhesive coating to the forming tooling, which is designed to minimize the effort exerted when removing its individual elements at the extrusion stage and to ensure a high-quality surface of the product.

The previously used silicone release coating (prototype) showed that the adhesion between the release coating of the filler is 1.5-2.0 kgf / cm ² . With this amount of adhesive strength, a cured composite material remains on the surface of the tooling for molding composite materials, and the pressed product has surface defects.

The prototype has high adhesive properties, which leads to a violation of the structural integrity of the inner surface of the product, the formation of breakouts of the filler and distortion of the mechanical characteristics, which is extremely undesirable. The proposed release coating contains dimethylsiloxane and heterosiloxane, which are capable of absorbing the filler plasticizer at an elevated temperature during vulcanization of the product and releasing it back upon cooling, when their mass capacity decreases. The use of the claimed composition can reduce adhesion by more than 15 times compared with the prototype. The proposed coating allows to obtain a high-quality surface of the molded product after extrusion. Molded release tools can be used at least five times. The strength values of the connection of the filler with the proposed release coating are shown in the table.

The content in the composition of the release coating below the specified limit of dimethylsiloxane and heterosiloxane leads to a decrease in the physicomechanical characteristics of the coating, which leads to an increase in the curing time of the soil and the first coating layer, an increase in the content of dimethylsiloxane and heterosiloxane complicates the process of coating the equipment and increases its consumption. A decrease in the content of CIATIM lubricant below 5% leads to an increase in adhesive strength, and an increase in the content of the specified plastic lubricant above 20% will lead to the formation of grease deposits on the surface of the pressed samples, which indicates its excess.

In the primer layer of the proposed composition, methyl triacetoxysilane or tetraepoxylan with tin diethylcaprylate or tetraepoxylan with tin dibutylurethane are used as a hardener, and nephras of grades C2-80 / 120, C3-80 / 120 or gasoline are used as a hardener.

In the first layer of the coating layer, polyaluminosiloxane or chromosiloxane rubber is used as heterosploxane, tin diethyl dicaprylate in ethyl silicate or diethyl aminomethyltriepoxysilane is used as a curing catalyst, and benzene grades C2-80 / 120, C3 are used as a solvent.

In the second layer of the coating layer, TsIATIM grease of grades 201, 202 is used (see GOST 6267-74 and RU 2131451 C1, 10.06.1999), and Nefras grades C2-80 / 120, C3-80 / 120 or gasoline are used as a solvent.

Examples of specific performance.

Example 1

Primer coat: (wt.%)

Dimethylsiloxane 10 Methyltriacetoxysilane one Nefras C2-80 / 120 89

Cover layer: (wt.%)

For the first layer:

Polyaluminosiloxane rubber twenty Tin diethyl dicaprylate ethyl silicate 0.8 Nefras C2-80 / 120 79.2

Second layer

CIATIM 201 5 Nefras C2-80 / 120 95

Example 2

Primer coat: (wt.%)

Dimethylsiloxane fifteen Tetraeposiloxane with dutylcaprylate tin 1,5 Nefras S3-80 / 120 83.5

The coating layer (wt.%)

For the first standing:

Polyaluminosiloxane rubber 29.64 Diethylaminomethyltriepoxysilane 1.19 Nefras S3-80 / 120 69.17

For the second layer:

CIATIM 202 10 Nefras S3-80 / 120 twenty

Example 3

Primer singing: (wt.%)

Dimethylsiloxane twenty Tetraepoxylan with Dibutyl Aurenate tin 2 Petrol 78

Cover layer:

For the first layer:

Chromosiloxane rubber 40 Diethylaminomethyltriepoxysilane 1,6 Petrol 58.4

For the second layer:

CIATIM 202 twenty Petrol 80

For all cases of using a release coating, the surface of the pepper equipment by applying a primer should be cleaned of sediment and filler. The equipment prepared for applying the release coating is degreased with a solvent and dried for 30 minutes. The priming and coating layers are applied manually on the working surfaces of the tool with a hair brush, and on small parts of the equipment by dipping or pouring.

The primer layer is applied in two steps, drying between applications is 1.0-1.5 hours, curing after the last application occurs within 24 hours at a temperature of plus 15 to 35 ° C, 8 hours at a temperature of plus 75 to 85 ° C or 4 hours at a temperature of plus 145 to 155 ° C. When the primer coating is cured at elevated temperatures, the equipment is maintained until the coating layer is applied for at least 3 hours. Before applying the coating layer, the equipment coated with the primer layer is wiped with alcohol and dried for 20 minutes.

The coating layer is applied to the equipment, covered with a primer layer, no later than 24-28 hours after the curing of the primer layer.

The coating layer is made of two layers. The first layer is applied in 3-5 steps, drying between applications is from 30 minutes to one hour. Curing of the coating is carried out at a temperature from plus 15 to 35 ° C and a relative humidity of 65% from 6 to 24 hours

A second layer of coating composition consisting of a solution of CIATIM lubricant in an organic solvent is applied to the tool with a cured first layer. The solution is applied manually with a hair brush in one layer, drying for at least 3 hours.

Table
Compositions of release coatings and their properties Example Compositions (components in%) Assessment of the adhesive interaction of AAP with filler Installation parameters when pressing samples ⌀30 mm, L = 180 mm for primer for cover layer σ _AAPc ,
kgf / cm ^{2 *} The nature of the destruction ^** Oil station pressure,
kgf / cm ² Mold surface condition Sample surface condition the first second one 2 3 four 5 6 7 8 9 1 prototype methyltriacetoxysilane - 1.9 dimethyldiacetoxysilane - 0.1
water - 98 polyorganosiloskan - 10
hexane - 90 polyorganosiloxane - 5.8 polymethymetallosiloxane - 3.4
hexane - 90 2.0 N 22-35 filler coating strips of filler, indentation of the pusher 2 dimethylsiloxane - 10 hardener - 1 solvent - 89 heterosiloxane - 20
curing catalyst 0.8
solvent - 79.2 CIATIM - 5, solvent - 95 0.12 BUT 10-22 no AAP damage smooth, without damage 3 dimethylsiloxane - 15 hardener - 1.5 solvent - 83.5 heterosiloxane - 29.64; curing catalyst - 1.19; solvent - 69.17 CIATIM - 10, solvent - 90 0.06 BUT 5-10 no AAP damage smooth, without damage four dimethylsiloxane - 20 hardener - 2 solvent - 78 heterosiloxane - 40
cure catalyst 1.6
solvent - 58.4 CIATIM - 20, solvent - 80 0.001 BUT 5 no AAP damage smooth, without damage ^* Adhesion strength (σ _APP ) was obtained on the samples as a result of processing according to the method of БЖУИ 770304.009 ПМ 9
^** N - samples having a filler coating, A - samples without filler residues on the AARP.

Claims (1)

A release coating comprising a primer and a two-layer coating layer based on organosilicon compounds, characterized in that the primer layer is based on a composition having the following composition, wt.%: Dimethylsiloxane 10-20 Hardener 1-2 Organic solvent Rest and the coverslip is made in the following ratio of components in the compositions, wt.%: for the first layer: Heterosiloxane 20-40 Curing catalyst 0.8-1.6 Organic solvent Rest for the second layer: Tsiatim 5-20 Organic solvent Rest