CS232370B1 - Antiadhesive and lubricating agent for hot glass molds - Google Patents

Abstract

The invention relates to a release coating formed on the walls of glass molds used in blowing and pressing molten glass, which enables easy demolding of molded products. The coating consists of a polymer matrix based on special polymers, polypropylene, or ethylene-propylene copolymer of liquid or solid consistency, to which solid lubricants are added, e.g. graphite, molybdenum disulfide and sulfur. The melting point of the polymer matrix is increased by the addition of vulcanizable ethylene-polypropylene rubber.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-adhesive and lubricating agent for molds, in particular blow molding and hot glass molding, which facilitate the molding of molded articles.

For the production of wrought glass products, usually metal molds are used in which a measured amount of molten glass is metered and converted into the desired shape by blowing or pressing. The molten and hot glass is highly tacky at processing temperatures, and it is therefore necessary to provide mold parts in contact with the hot glass with an anti-adhesive coating to ensure easy demolding. The need for efficient separators increases with increasing use time of molds whose surface is broken due to high working temperature, refining and erosion by the glass and exhibits increasing adhesion to the glass.

For this reason, it is common to use various preparations, so-called lubricants, in the glass forming process, which allow easy removal of the products and / or molds. of semi-finished products from the mold at operating temperature. These preparations are various mixtures of silicones, mineral oils and fats with the addition of graphite. For automatic pressing, the machine manufacturer prescribes the use of a semi-solid lubricant DAMCHEX rubber-like constitution, matured in contact with hot water. This lubricant resembles certain types of fact in rubber industry.

For automatic lines where separation requirements are highest and the lubricant function often determines the flow, yield and process performance, it is used with the success of the imported DAMCHEX, the advantage of which is that it maintains efficiency for multiple duty cycles. The disadvantage of this lubricant is its relatively high price.

The above-mentioned drawbacks eliminate and all the required functions are fulfilled by the anti-adhesive and lubricating coating of the hot glass molds according to the invention, which consists in

2,232,370 from 86 to 97 parts by weight of atactile polypropylene, from 3 to 10 parts by weight of stereoblocks of polymer fractions of polypropylene and from 0.1 to 4 parts by weight of isotactic polypropylene. The polymer matrix may further comprise 0.1 to 15.0 parts by weight of vulcanized ethylene-propylene rubber. Another lubricant enhancing component may be the addition of 0.1 to 15 parts by weight of graphite, molybdenum disulphide or mixtures thereof and / or sulfur in an amount of 0.1 to 15 parts by weight.

Lubricants based on special polymers of propylone of different consistencies which degrade at working temperatures have been found to have an effect similar to DAMCHEX ”; decomposition products have a separating effect and at the same time prevent surface oxidation of the molds. The antioxidant effect can be increased by special additives of a reducing nature.

For the mold function, in addition to the separating effects, a lubricating ability of the composition is required to ensure sufficient mobility of the functional parts of the molds. This can be achieved by the addition of the polymer matrix by the addition of solid lubricants such as graphite, moly, sulfur, etc. The advantage of the polypropylene-based system is their availability and low cost. Atactic proportions of polypropylene are even waste ·

In practice, it has been shown that another important property required for a lubricant is the ability to form a sufficiently weak coating on molds operating at different temperatures in a short time. If the separator is overdosed locally, the surface defects of the products will occur until the excess of the separator is removed by further enamel batches.

It has been found that forming processes with lower operating temperatures of the molds are more advantageous liquid separators and the higher the farm temperature, the higher the melting point of the release agent is required. This is understandable because the polymer is too easy to melt! mixtures tend to predose. In some cases, it is even necessary to reduce the meltability of the composition by partially crosslinking the polymer matrix.

The process of forming the protective coating is simple. The application of the oily mixture can be done by screed or by spraying. In solid formulations, direct contact of the molded separator with the hot mold wall is used. Due to the high temperature, the melted composition disperses on the mold surface.

- 3 Example 1

232 370

A blend of 100 parts by weight of polypropylene oil K 1000, a blend of broadly branched, atactic, branched polyolefins, was used to separate and lubricate molds of a cup blow molding machine operating at a temperature of 200 * 350 ° C. molecular weight distribution, with 14 parts by weight of higher waxy polymers consisting of a mixture of stereoblocks and isotactic polypropylene in a ratio of 5 to 2, and a melting point of 180 to 200 ° 0. The lubricant prepared in this way was applied to the functional parts of the molds.

Example 2

A solution of 100 parts by weight of a mixed atactic polypropylene containing 8% by weight of atactiocol, 4 isocactic and 1Cp stereoblock components in 100 parts of polypropylene oil was used as a separating and lubricating agent to convert the molds of the blow molding machine to temperatures of 200-35 ° C. ® K 1000, made up of atactic polyolefins · 0.2 parts by weight of molybdenum disulfide and 0.2 parts of sulfur flower were added to the solution. The mixture was thoroughly dispersed in a ball mill · The prepared separator was applied to the functional parts of the molds ·

Example 3

Separation and lubrication mixtures consisting of 100 parts by weight of mixed ethylene-propylene rubber consistency fractions of gummy consistency containing atactic, isotactic and O-stereoblock components were used for separaoi molds of cup stalk press operating at temperatures of 400 ° C to 500 ° C. polypropylene, with 2 parts by weight of ethyl-propylene rubber DUTRAi, 4 parts of sulfur and 1 part of captax.

The mixture was prepared by calendering followed by vulcanization at 150 ° C for 30 minutes · The heated vulcanized mixture was formed into a thick foil on a rubber calender ·

Tapes and sticks were then cut from the foil to lubricate and separate the molds.

Example 4

For separaoi molds of the press machine for stem stems operating at temperatures of 400 to 500 ° C, a lubricant was obtained.

- 4,232,370 blended by mixing 100 parts by weight of the mixed atactic fractions as in Example 3 with 3 parts ethyl propylene rubber, 4 parts sulfur, 2 parts molybdenum hum and 2 parts graphite · The mixture was calendered, partially vulcanized in an oven at 180 ° C and from the prepared mixture a thick foil was formed on the calender from which the squares used for mold lubrication were cut.

Claims (3)

SUBJECT OF THE INVENTION 232 37 ( A non-adhesive and lubricating agent for hot glass forming molds, characterized in that it consists of 86 to 97 parts by weight of atactic polypropylene, 3 to 10 parts by weight of the polymer fractions of polypropylene and 0.1 to 4 parts of isotactic polypropylene. 2. The anti-adhesive and lubricant composition of claim 1, further comprising from 0.1 to 15.0 parts by weight of vulcanizable ethylene-propylene rubber. 3. Anti-adhesive and lubricating agent according to Claims 1 and 2, characterized in that it contains an additive of 0.1 to 15 parts by weight of graphite, molybdenum disulfide or a mixture thereof and / or sulfur in an amount of from 0.1 to 15 parts by weight.