DK172536B1 - Process for preparing aqueous dispersions of plant protection products containing swelling agents - Google Patents

Abstract

1. A process for mixing a solid swelling agent with an aqueous plant protection agent dispersion, wherein the mixing is carried out in a colloid mill.

Description

in DK PR 172536 B1

The present invention relates to a process for mixing a solid swelling agent with an aqueous plant protection product dispersion.

Most commercially available dispersions of plant protection products contain, in addition to water as a carrier liquid, the active substance, as well as humectants and dispersants and anti-foaming agents, additional swelling agents. The latter serves, for example, to increase the storage stability of the dispersions and to prevent the formation of 10 precipitates.

According to West German publication no.

2,924,403, the preparation of plant protection product dispersions by wet milling of the materials by means of friction ball mills is known. This is done by mixing the components in a mixing vessel and then milling them in friction ball mills. In the known methods, the swelling agent, e.g. polysaccharides, aluminosilicates or xanthan gum, in the form of aqueous concentrated solutions for the premix thus prepared.

20 The major disadvantages of this process are that the added solutions of quenching agents, in spite of low levels of quenching agents, become very high viscous and are thus difficult to handle. Aqueous solutions of swelling agents, scan are extracted from natural substances, e.g. polysaccha-25 rides, upon standing, has a strong propensity for mold formation, so that the solutions become useless. Also unfortunate is the fact that in the milling process in the friction ball mills, the swelling agent solutions change in the direction that their stabilizing properties are diminished or even completely lost.

By adding aqueous solutions of swelling agents, an undesirable dilution effect of the dispersions of plant protection products is usually obtained. Therefore, in order to compensate for this dilution effect, it is necessary to use a high concentration of active compound in the dispersion to use corresponding concentrated dispersions of active compound in the milling process. When grinding dispersions with elevated concentrations of active compound, especially when using active substances melting between 70 ° and 100 ° C, an agglomeration or baking may occur. As a result, the grinding process can completely stall. If active substances with a melting point higher than 100 ° C are used, e.g. lsopro-turon or carbendazim, grindingly high viscous dispersion concentrates are also often not available.

Addition of swelling agents by simple admixture to the dispersions of plant protection products was previously very problematic, since no good distribution of the swelling agent was obtained in the dispersion of active compound. This is because the swelling agent is present in a very low concentration of only approx. 0.1% by weight of the plant protection product dispersion. Thus, at an amount of 4 h of plant protection product dispersion, only 4 kg of swelling agent is added. As a result of stirring the swelling agent into the aqueous dispersion, light co-2 ° clumping occurs as a result, and the swelling agent can also easily adhere to the agitator.

The object of the present invention was therefore to find a method which allows swelling agents to be added to plant protection agent dispersions without the above problems occurring.

It has now surprisingly been found that the process according to the invention achieves a significantly reduced grinding time, which leads to time and energy savings, 30 - clearly better flow properties with the mixed nitrogen and thus a better stability of the dispersions and - no clumping at mixture of swelling agent and dispersion.

The present invention thus relates to a method for mixing a solid swelling agent with an aqueous plant protection agent dispersion, and the process of the invention is peculiar to the milling being carried out in a colloid mill.

For example, as colloid mills, dental disc, corundum disc or wet cutting mills can be used (see D. Seidel, Maschinenmarkt, Wiirzburg 85 (1979), page 44), preferably dental disc colloid mill. To date, only the use of such colloid mills for the refinement of plant protection products is known. However, in the process of the invention 10, no actual milling process occurs since the active substances in the dispersion are already in finely ground state.

In the method of the invention, the dispersion of plant protection agent is conveniently conducted via a suitable set, suitably a funnel-shaped set, thus into the colloid mill, until a funnel-shaped bow is formed in the dispersion, hereinafter referred to as a drum. In this trombone, the swelling agent is dosed on liquid, ie. dissolved or suspended form, with water or organic solvents being used as liquid, e.g. polyglycols, or in solid form, especially in solid form. For this, a conventional dosing device, e.g. a Gericke dosing device from the company Gericke.

25 In the colloid mill, the dispersion and the added swelling agent are thoroughly mixed due to the high shear forces when passing through the mill. Hereby the desired distribution of the swelling agent occurs.

The dispersions of plant protection products thus prepared can be stored without problems and are very stable. The swelling agent is optimally distributed in the dispersion.

As aqueous dispersions of plant protection products, all common plant protection product dispersions 35 can be used, as described above, for example, according to West German publication no.

DK PR 172536 B1 4 2,924,403 by wet grinding by means of friction ball mills. Thus, the dispersions contain the usual wetting, adhesive, emulsifying and dispersing agents and additional additives, such as antifoaming agents and preservatives. Wetting agents are, for example, polyoxyethylated alkyl phenols, polyoxyethylated oleyl or stearyl amines, alkyl or alkyl phenyl sulfonates. Examples of dispersants include: lignin sulfonic acid sodium, 2,2'-dinaphthyl-methane-6,6'-disulfonic acid sodium, dibutyl-10-naphthalene sulfonic acid sodium, oleyl methyl tauric acid sodium, Na-lauryl ether phosphate, condensation products made of polyglycol ethylene ( ethylene oxide and formaldehyde), sodium sulfite and maleic anhydride (West German Patent No. 2,132,405, so-called sulphoric acid ester alkali metal salts) or condensation products of cresol, formaldehyde and sodium bisulfite. For example, emulsifiers may be used: alkylrylsulfonic acids calcium salts, fatty acid polyglycol esters, alkylaryl polyglycol ethers, fatty alcohol polyglycol ethers, polyoxyethylated oleyl or stearylamines, propylene oxide-ethylene oxide condensation and alkylene oxide acid, tion products.

Furthermore, any conventional active substances may be used for the dispersions, e.g. the active substances carbendazim, isoproturon, linuron, endosulfan and mono-linuron.

As a swelling agent, all common swelling agents such as polysaccharides, e.g. such as may be prepared from the corresponding natural products by means of xanthomonas bacteria, aluminosilicates such as montmorilionite or bentonite type, e.g. hectorite ®, xanthan gum, gum arabic or alanates, especially polysaccharides. These are commonly used in concentrations of 35 0.01 to 1% by weight, especially 0.04 to 0.3% by weight, calculated from the total plant protection product dispersion.

DK PR 172536 B1 5

The process of the invention is illustrated by the following examples.

Example 1 99.9 parts by weight of an aqueous carbendazime dispersion (carbendazime = 2-methoxycarbonylamino-benzimidazole) having the following composition 40% by weight of active compound 12% by weight dispersant (sulphuric acid half-ester sodium salt, prepared by reaction of a polyglycol ether based on nonylphenyl, ethylene oxide and formaldehyde with sodium sulfite and maleic anhydride) 2 wt% sodium lignin sulfonate 2 wt% antifoaming agent (type SE 2, Wacker-Chemie, Munich) 4 wt% alkyl polyglycol ether 20 wt% ethylene glycol 35 wt% water by first grinding , is fed to a toothed colloid mill (type ^^ UC mill from the company Probst und Clasen) via a hopper set until a drum is formed in the dispersion. In this thrombus, 0.1 parts by weight of a solid polysaccharide (Rhodophol ®23) is dosed via a Gericke dosing device over a period of approx. 2 minutes and the two components are mixed intensively with each other in the mill.

The dispersion of plant protection products thus produced is stable over a period of 3 months at 50 ° C.

DK PR 172536 B1 6

Example 2 99.95 parts by weight of a final aqueous isoproturon dispersion (isoproturon = N-4-isopropylphenyl-N, N'-dimethylurea) having the following composition 5 46.5% active compound 6% dispersant (condensation product of cresol, formaldehyde) and sodium bisulfite) 3% Na lauryl ether phosphate (Forlanit®P, Fa. Henkel) 1% antifoam (type SE2) 10% ethylene glycol 0.05% preservative (Bronidox L, Fa. Henkel) 33.45% water is mixed as described in Example 1 with 0.05 parts by weight of Kelzan ® S (a polysaccharide) in the P (JC ® mill). The thus-prepared nitrogen-containing dispersions thus stored are stable for three months at 50 ° C.

Claims (7)

A process for mixing a solid swelling agent with an aqueous plant protection product dispersion, characterized in that the milling is carried out in a colloid mill. Process according to claim 1, characterized in that a plant protection product dispersion is led to a colloid mill until a thrombus is formed and the swelling agent is dosed to that thrombus. A method according to claims 1 to 2, characterized in that a dental disc, corundum disc or wet cutting mill is used as a colloid mill. Method according to claims 1 to 3, characterized in that a dental disc colloid mill is used. Process according to claims 1-4, characterized in that polysaccharides, aluminosilicates, xanthan gum, gum arabic or alginates are used as swelling agents. 6. A process according to claims 1-5, characterized in that 0.01 to 1% by weight of swelling agent is used in relation to the total dispersion of plant protection product. Use of colloid mills for mixing solid swelling agents with aqueous plant protection product dispersions.