CS242810B1 - Filled mixture based on latex of natural or synthetic rubber - Google Patents

Abstract

The invention relates to filled mixtures based on natural or synthetic rubber latex containing vulcanizing agents, dispersants, stabilizers, accelerators, activators, antioxidants, pigments and other auxiliary additives. Inorganic fillers are used in the mixture to adjust some properties of latex products and, above all, to reduce their cost. However, their use is limited to relatively small amounts, since otherwise their settling in production equipment makes the production process difficult or impossible. According to the invention, this deficiency is eliminated by adding 0.1-5 parts by weight of an aqueous dispersion of silicon dioxide with a particle size of 10-20 nm. Latex mixtures with a silicon protective colloid have increased sedimentation stability and can be filled with a larger amount of inorganic fillers. The invention also relates to a method for producing the above mixtures by mixing a separately prepared mixture of latex, additives and a protective colloid with a dispersion of the filler.

Description

Filled mixture based on latex of natural or synthetic rubber

The present invention relates to filled latex-based natural or synthetic rubber compositions comprising vulcanizing agents, dispersants, stabilizers, accelerators, activators, antioxidants, pigments and other adjuvants.

Inorganic fillers are used in the mixture to modify some of the properties of the latex products, and especially for cheaper products. However, their use is limited to relatively small amounts, since otherwise their deposition in the production facilities makes it difficult or even impossible to make the production process.

According to the invention, this drawback is achieved by adding 0.1-5 parts by weight of an aqueous silica dispersion having a particle size of 10-20 nm. Latex mixtures with a silica protective colloid have increased sedimentation stability and can be filled with more inorganic fillers.

The invention also relates to a process for preparing said compositions by mixing a separately prepared mixture of latex, additives and protective colloid with a filler dispersion.

242 810

242 810

The invention relates to filled latex mixtures based on natural or synthetic rubber containing vulcanizing agents, dispersants, stabilizers, accelerators, activators, antioxidants, pigments and other auxiliaries, as well as a process for preparing these mixtures.

The compositions according to the invention are intended for the production of rubber articles by dipping. This technology currently produces a number of rubber products such as gloves (for various technical used, operational, household), protective equipment, advertising and meteorological balloons.

For most applications latex mixtures based on natural or synthetic rubber, or mixtures thereof containing the usual additives such as vulcanizing agents, dispersants, stabilizers, accelerators, activators, antioxidants, pigments and other auxiliaries are used.

Inorganic fillers such as limestone, chalk, kaolin, lithopone, barium sulphate, which are commonly used in other latex technological processes for the treatment of hardness or stiffness, but mainly for latex mixtures, are used only to a limited extent when soaked · Used fillers cannot be added into latex mixtures by direct mixing, but the fillers must be premixed in water using suitable dispersants and then subjected to a particle dispersion process in one of the grinding equipment (ball, colloid and atritor mill).

242 810

Substances used as proven dispersants - ammonium, sodium or potassium oleate, sodium salt of alkylnaphthalenesulphonic acid and its various derivatives, or the condensation product of oleil chloride and methyltaurine are sufficient for satisfactory dispersion of additives supplied to latex mixtures (colloidal sulfur, accelerators, antioxidants, vulcanizing additives, pigments) in small quantities of the order of 1-5 parts per 100 parts of rubber (dsk). These dispersants allow wetting and dispersing of the inorganic fillers in water, but when the dispersed fillers are used in amounts of 10 dsk or more in latex mixtures, the filler particles are gradually sedimented. If the mixtures are not permanently mixed, a hardly stirred sediment forms at the bottom of the vessels, pipes, hoses and containers, which makes it difficult or impossible to use fillers in the continuous production of soaked goods. Other known dispersants of natural origin, such as casein, glue, gelatin, ammonium alginate, also exhibit low efficacy and, when used in large quantities, increase the wettability of the film and coagulate latex due to their biodegradation.

Since it is not possible to ensure continuous mixing of the filled latex mixture at all stages of the soaking process, the use of inorganic fillers in the present process of making the mixture is completely unrealistic, although the physical-mechanical properties of the filled rubber products are satisfactory for most applications.

Although sedimentation can be suppressed by significantly reducing the particle size of the fillers, this affects the technical capabilities of filler manufacturers and suppliers. The second possibility of increasing the sedimentation stability by increasing the viscosity of the latex mixture by using different thickeners is very limited, since the soaking technology requires only a narrow viscosity range of the latex mixture to achieve a uniform appearance and thickness of the products.

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242 810

The purpose of the invention was to prepare a latex mixture filled with inorganic fillers of such a composition as to achieve a long-term sedimentation stability allowing a continuous technological soaking process. It has been found that a latex mixture based on natural or synthetic rubber containing vulcanizing agents, dispersants, stabilizers. accelerators, activators, antioxidants, fillers, pigments and other auxiliary additives, characterized in that it contains 5-50 parts by weight of inorganic fillers such as limestone, chalk, barium sulfate or kaolin per 100 parts by weight of latex and 0.2-10 parts by weight protective colloid based on a colloidal aqueous dispersion of silica having a particle size of 10-20 nm.

In preparing the latex composition of the present invention, an aqueous dispersion of an inorganic filler with a dispersant and a latex composition containing vulcanizing agents, stabilizers, accelerators and other adjuvants and a protective colloid according to the invention are separately prepared, followed by addition of the inorganic filler dispersion to the mixture. latex blends.

Colloidal aqueous dispersion of silica with particle size 10-20 nm creates a spatial mesh in the latex mixture, which apparently increases the viscosity with a thixotropic effect. This thixotropy suppresses the sedimentation of the particles in unmixed filled mixtures and eventually the formed sediment is inconvenient and easy to mix.

In order to further elucidate the invention, the following examples of compositions according to the invention are given.

Example 1

The dissolver mixer is used to prepare a premix filler composition (in parts by weight):

Precipitated calcium carbonate

Distilled water

Disperser (based on condensate of sulphonated alkylnaphthalene with formaldehyde) 1

- 4,242,810

The premix is dispersed in an attritor mill with a glass bead filling at 1000 rpm for 10 minutes · (The ratio of bead filling and masterbatch is 1.5: 1.0). The prepared filler premix has a dry matter content of 61%, a viscosity of 15 s (FOBD 0 4 mm). · Using this premix, a filled soaked composition (in parts by weight) was prepared while stirring:

Latex natural rubber (60%) 100.00

Disperser (based on condensate of sulphonated alkylnaphthalene with formaldehyde

Sulfur ground 0,62

Zinc alkylthiocarbamate accelerator 0.62

Titanium dioxide - rutile 1.20

Silicone emulsion 0.07

Color premix 0,04

Distilled water 3,80

Precipitated calcium carbonate premix 25.00

Colloidal water dispersion of silica (30

1.00

This filled dipping latex mixture has good mechanical stability (min · 1000 with KL.XON), the filler does not sediment in the mixture · Slight haze, which is formed after 14 days of standing, can be easily mixed, the coagulability of the mixture is comparable to latex-free fillers ·

The mixture can be used for the production of soaked goods, especially the hand for household and industry, technical gloves and advertising balloons.

Example 2

The dissolver mixer is used to prepare a master batch of the filler composition (in parts by weight):

Kaolin 45,0

Distilled water 54.0

Disperser (based on condensate of sulphonated alkylnaphthalene with formaldehyde)

1.0

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The masterbatch is dispersed in an attritor mill filled with steel or glass beads at 1000 rpm, 15 minutes · (The ratio of bead filling and masterbatch is 1.5: 1.0). The prepared filler premix has a dry matter content of 46 s viscosity (FORD 0 4 mm).

Using this pre-mix, a steeped soaked composition (in parts by weight) was prepared with stirring:

Latex natural rubber (60%) 100.00

Disperser (based on condensate of sulphonated alkylnaphthalene with formaldehyde)

Sulfur ground 0,62

Zinc alkylthiocarbamate accelerator 0.62

Titanium dioxide - rutile 1.20

Silicone emulsion 0.07

Color premix 0,04

Distilled water 3,80

Kaolin masterbatch 65.00

Colloidal silica solution (30%) 2,50

This filled latex mixture for steeping has good mechanical stability (min. 1000 with KIAXON), the filler does not sediment in the mixture.

The slight haze produced by standing can be easily mixed, the coagulability of the mixture being comparable to the latex-free filler.

The mixture can be used for the production of dipped goods especially household and industrial gloves, technical gloves and advertising balloons.

Example 3

Using the masterbatch prepared according to Example 1, a filled soaked composition was prepared with the mixing (in parts by weight):

Latex butadiene - acetonitrile dry matter content 45%) 100

Disperser (based on condensate of sulphonated alkylnaphthalene with formaldehyde)

Example 3

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Using the masterbatch prepared according to Example 1, a filled soaked composition was prepared with the mixing (in parts by weight):

Latex butadiene acrylonitrile (dry matter content 45%)

Disperser (based on condensate of sulphonated alkylnaphthalene with formaldehyde)

Sulfur ground

Accelerator (zinc diethyldithiocarbaman)

Titanium dioxide - rutile

Colorful premix

Silicone emulsion

Distilled water

Precipitated calcium carbonate premix

Colloidal aqueous dispersion of silica (30%)

100 ALIGN!

0.20

0.46

0.46

0.90

0.03

0.05

2.05

10.80

0.60

The soaked soaked latex mixture has satisfactory mechanical stability (min · 1000 with KIAXON), the filler does not sediment in the mixture · The low haze formed after standing for 14 days is easy to mix, the coagulability of the mixture is comparable to the latex-free filler ·

The mixture can be used for the production of dipped goods, especially technical gloves resistant to solvents and oils ·

Claims (2)

SUBJECT OF THE INVENTION 242 810 1 · A natural or synthetic rubber latex filled composition containing vulcanizing agents, dispersants, stabilizers, accelerators, activators, antioxidants, pigments and other auxiliaries, characterized in that it contains 5-50 parts by weight of inorganic filler such as limestone per 100 parts by weight of latex , kaolin, barium sulfate or chalk and 0.1-5 parts by weight of a protective colloid based on a colloidal aqueous dispersion of silica having a particle size of 10-20 nm. 2. The process of claim 1 wherein the aqueous dispersion of an inorganic filler with a dispersing agent and a latex composition containing vulcanizing agents, stabilizers, accelerators, activators, antioxidants, pigments and other auxiliaries and an aqueous-based protective colloid are separately prepared. silica dispersion, followed by the addition of an inorganic filler dispersion to the latex mixture while stirring.