JPS5838404B2 - Method for producing solid granular herbicide composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing solid formulations containing herbicides, particularly bipyridylium herbicides.

Various herbicidal bipyridylium quaternary salts are disclosed in British patent no.
No. 85732, No. 813531 and No. 8135
It is described in the specification of No. 32.

Typically, these compounds are produced in the form of concentrated aqueous solutions for use in agriculture.

When used, these concentrated aqueous solutions are diluted with water to obtain a dilute solution, which is then sprayed onto the weeds.

For various reasons, including packaging considerations, it is advantageous for pipyridylium herbicides to be provided in solid form rather than in aqueous solution form.

Although various methods have been proposed for producing solid formulations of herbicidal bipyridylium quaternary salts, all of these formulations have traditionally been unsuitable for widespread commercial use in agriculture. known from.

GB 813,532, for example, describes a powder formulation consisting of a mixture of the herbicidal bipyridylium quaternary salt and an inert powder diluent, such as talc, china clay, gypsum or basic slag. .

However, such powder formulations are inconvenient for agricultural use of bipyridylium herbicides and are therefore not used commercially.

GB 1,086,937 discloses that an aqueous solution of a herbicidal bipyridylium quaternary salt is mixed with a hydrate-forming salt in a proportion that combines a sufficient amount of its water content to provide a solid composition. A method for producing a solid herbicide composition is described.

Compositions produced in this way are sold on the retail market for use in home gardens.

However, these compositions are unsuitable for use in canine quantities in agriculture.

This is because the composition has a relatively small active fraction and the composition does not dissolve quickly enough.

Yet another method for producing solid herbicide compositions is described in Japanese Patent Publication No. 48-3381.

In the method described in the publication, an aqueous solution of a bipyridylium herbicide is absorbed into preformed granules of water-soluble salts.

However, even in this method, the above-mentioned British patent No. 1
As in the method described in No. 086937, only formulations with relatively low concentrations of active ingredient can be conveniently produced.

We have now developed a method by which solid granular preparations can be produced containing a relatively high proportion of the bipyridylium quaternary salt used as active ingredient.

According to the invention, therefore, an aqueous solution of herbicidal bipyridylium diquaternary salt is introduced into a fluidized bed of solid diluent particles maintained at an elevated temperature, thereby rapidly evaporating said aqueous bipyridylium salt solution to form a solid diluent. A solid comprising a herbicidal bipyridylium diquaternary salt and a solid diluent, characterized in that the bipyridylium diquaternary salt is deposited on the particles and the solid granular composition thus obtained is collected. A method of making a granular herbicide composition is provided.

The term fluidized bed is well known in the chemical process art.

That is, the term relates to a process in which gas is passed through a solid particulate material at such a velocity that the particulates are suspended in motion in the gas stream.

The particle layer (or "bed") exhibits highly turbulent conditions similar to a boiling liquid.

In the present invention, it is preferred to use air as the gas for fluidizing the solid particulate material.

However, if desired, other gases (e.g. nitrogen)
may also be used.

The fluidized bed is maintained at an elevated temperature by heating the gas stream that fluidizes the bed.

The temperature of the heated gas stream is between 100 and 250°C, for example between 120 and
Preferably, the temperature is 150°C.

The fluidized bed temperature can be, for example, 50-100°C.

The aqueous bipyridylium quaternary salt solution can be introduced into the fluidized bed by spraying from one or more spray nozzles.

If desired, the aqueous solution itself can be heated, but no particular benefit is obtained thereby.

The concentration of the bipyridylium quaternary salt solution is preferably high, for example at least 200 r of bipyridylium quaternary cation per liter of solution, in order to reduce the amount of water that has to be evaporated. .

Surprisingly, it is not necessary that the solid particulate diluent be insoluble in water.

The evaporation of water from aqueous solutions occurs very rapidly, creating difficulties when using granules that dissolve in aqueous solutions of bipyridylium quaternary salts, even when using water-soluble diluents such as sodium chloride. do not have.

Therefore, both water-soluble and water-insoluble diluents can be used as diluents.

However, it is preferred to use a diluent that is freely soluble in water, so that when the solid composition of the invention is used for weeding, this solid diluent will dissolve completely and rapidly. The spray solution can be prepared using

If an inorganic salt is used as a diluent, the inorganic salt should be substantially water-free and crystalline, since hydrated salts may burn and burst in the heated air stream.

Salts that react with alkalis in aqueous solutions, such as salts that exhibit a pH of about 8 or higher when dissolved in water (e.g. sodium carbonate)
It is not preferred to use bipyridylium quaternary salts as solid diluents in the present invention because bipyridylium quaternary salts are unstable in high pH solutions and salts such as those mentioned above are therefore not suitable for use as solid diluents. This is because it may have an adverse effect on the active ingredients inside.

The rate of air flow required to flow a solid particulate diluent will vary depending on various factors, such as the particle size of the diluent and its density.

Suitable speeds can be easily determined by practicing the method of the invention, and the technology of methods using fluidized beds is well known to those skilled in the art, but to give an example: 9
An air line velocity of ˜1.1 m was found to be adequate to maintain the fluidized bed of sodium chloride in a fluid state.

The herbicidal bipyridylium quaternary salt that can be used as an active ingredient of the herbicidal composition of the present invention has the formula: , alkoxy group, alkylcarbonyl group, alkoxycarbonyl group, carbamoyl group or N
- represents an alkyl group or alkenyl group having 1 to 4 carbon atoms which may be substituted by an alkyl-substituted carbamoyl group or a halogen atom; Xn represents an anion and n represents 1, 2, 3 or 4) include.

Preferred alkoxy groups have 1 to 4 carbon atoms.

Preferred alkylcarbonyl groups and alkoxycarbonyl groups have 2 to 5 carbon atoms.

Preferred N-alkyl substituent rubamoyl groups are those in which the alkyl group bonded to the carbon atom has 1 to 4 carbon atoms.
It is an individual thing.

Examples of herbicidal bipyridylium diquaternary salts are as follows: 1,1'-monoethylene-2,2'-bipyridylium dibromide (diquot dibromide), 1,1'-dimethyl- 4,4'-bipyridylium dichloride (baraquat dibromide), ■1'-di-2-hydroxyethyl-4,4'bipyridylium dichloride, ■1'-bis-3,5-dimethylmorpholinocarbonylmethyl- 4,47-Bipyridylium dichloride (
morphamquat dichloride), ■-(2-hydroxyethyl)-l'-methyl 4,4'-bipyridylium dichloride, ■,1'-dicarbamoylmethyl-
4,4'-bipyridylium dichloride, 1,1'-bis-N-N-dimethylcarbamoylmethyl-4,4'-bipyridylium dichloride, ■,1'
-Bis-N-N-diethylcarbamoylmethyl-4.4
'-Bipyridylium dichloride, ■・l'-G(
piperidinocarbonylmethyl)4,4'-bipyridylium dichloride, ■,1'-diacetonyl-4,4'
-bipyridylium dichloride, ■・1′-ethoxycarbonylmethyl-4・4′ bipyridylium dibromide, 1・1′-diaryl-47-bipyridylium difuromide, within the number 0 of some of the above compounds The names listed are the accepted common names for the cationic moieties of the above compounds.

For example, 1 paraquart'' is ■・1'-dimethyl-4・
4'-Bipyridylium is a common name for the cation.

Baraquat is a particularly preferred bipyridylium compound for use in the herbicidal compositions of the present invention.

Since the herbicidal effect of the bipyridylium quaternary cation is independent of the type of anion bound thereto, a convenient anion is selected depending on, for example, price.

Preferably, the anion is one that provides a salt with convenient water solubility.

Examples of anions, which can be monovalent or polyvalent, are acetic acid radicals,
Benzene sulfonic acid radical, benzoic acid radical, bromide ion, butyric acid radical, chloride ion, citric acid radical, fluorosilicate radical, fumaric acid radical, hydroborofluoride radical, iodide ion, lactic acid radical, malic acid radical, maleic acid radical, methyl sulfate radical, nitrate radical , propionate, phosphate, salicylate, co-citrate, sulfate, thiocyanate, tartrate and p-}luenesulfonate.

Salts of the herbicidal bipyridylium cation may be formed from a number of similar anions or mixtures of different anions.

For example, passing a pre-prepared salt through an ion exchange resin, either by direct synthesis from reactants containing the desired anion or by exchanging the anion of the pre-prepared salt with the desired anion according to well-known methods. By this, salts having any particular desired anion can be produced.

For convenience and economic reasons, chloride is the most preferred anion.

Since the characteristic herbicidal activity of the herbicidal bipyridylium quaternary cation salts is based solely on the cation, the concentration and application rate of the active ingredient should be
This eliminates the inconvenience of having to express different application proportions for the same bipyridylium quaternary cation due to different salt types.

Therefore, the application rates and concentrations indicated herein are:
Unless otherwise specified, amounts of bipyridylium quaternary cation are indicated.

As mentioned above, in carrying out the method of the present invention, the pipyridylium quaternary cation is used at a high concentration, for example, 1
Preference is given to using aqueous solutions containing a concentration of at least 200 parts per liter.

360 per 11? Concentrated solutions of high concentration may be advantageously used.

The herbicidal compositions produced by the method of the invention may also contain relatively high proportions of bipyridylium cations used as active ingredients; for example, a concentration of 20% by weight of bipyridylium cations is easily produced. and higher concentrations, for example up to 28% by weight or more, may be advantageously produced.

Preferably, the herbicidal composition contains at least 10% by weight of bipyridylium cations.

The method of the invention can be carried out batchwise or continuously.

The time required to complete production of the herbicidal composition will vary depending on, for example, the temperature and speed of the heated air stream.

For example, in a typical batch process, 5 ky of sodium chloride is fluidized in an air stream having a velocity of 60 meters per minute and a temperature at the inlet of the fluidized bed of 130°C.

A solution of paraquat dichloride (6 liters; 36(1) paraquat per liter) is sprayed into the fluidized bed from a spray nozzle for one hour or so.

After the above period of time, the collected product is a non-scattering granular solid containing 27% paraquart and no moisture.

The average particle size of these granules is 1 to 2 mm, and the bulk density is 1 ml.
The hit is 0.81'.

If desired, further ingredients may be included in the herbicidal compositions of the invention,
For example, a surfactant can be added.

This can be done in a variety of ways; for example, by adding a surfactant to
It can be blended into the bipyridylium salt aqueous solution introduced into the fluidized bed.

Alternatively, the bipyridylium salt solution and the surfactant solution can each be introduced separately into the fluidized bed.

The amount of surfactant used can be, for example, 10-20% by weight of the bipyridylium cation in the herbicidal composition.

However, it may also be appropriate to use larger or smaller amounts of surfactant depending on the intended use of the product.

Preferably, the surfactants used are cationic or nonionic surfactants.

Selection of a particular surfactant is readily within the skill of those skilled in the art of insecticidal formulations.

However, by way of example, nonionic surfactants useful in the herbicidal compositions of the present invention include ethylene oxide and aliphatic alcohols such as oleyl alcohol and cetyl alcohol or alkyl phenols such as octylphenol, nonylphenol and octylcresol. Examples include condensation products with

Other nonionic surfactants are partial esters derived from long chain fatty acids and hexitol anhydride, such as sorbitan monolaurate; condensation products of the above partial esters with ethylene oxide; and lecithin.

Examples of cationic surfactants are quaternary salts and condensation products of ethylene oxide and amines, such as "Ethomeen", "Duoquad" and "7) L
It is a substance commercially available under the registered trade name 'Arquad'.

The process of the invention can be carried out in conventional fluidized bed reactors.

The technique of using fluidized beds is well known in the chemical process art.

The reactor itself consists of a normally tubular or cylindrical vessel, placed vertically along its long axis and having a perforated plate closing the bottom.

The solid particulate material to be flowed is introduced into the reactor and placed on a perforated plate.

The gas used to flow the fluid material is forced under pressure through the perforated plate and moves upwardly through the fluid material.

The pressure downstream of the perforated plate is preferably maintained at a pressure slightly below the atmospheric pressure outside the apparatus, for example by the action of a fan provided to exhaust the outflow air from the reactor.

By employing such a method, even if, for example, a crack occurs in the wall of the reactor, fine particles are prevented from flowing out of the reactor.

In the process of the invention, the air effluent from the reactor is used to collect the fine powder particles which are too fine to remain in the fluidized bed and which flow out of the reactor by means of the air stream. Preferably, it is delivered to a device (eg, a cyclone).

As mentioned above, the aqueous solution of bipyridylium salt can be introduced into the fluidized bed by spraying from one or more spray nozzles.

The spray nozzle can be mounted, for example, in the wall of the fluidized bed reactor or in the center of the perforated plate.

It is convenient to pump the solution via a metering pump and control it by measuring the amount introduced.

A block diagram of an apparatus for implementing the invention is shown in the drawing.

Examples of the present invention are shown below.

EXAMPLE The process of the invention was carried out using granular calcium chloride and sodium chloride as solid particulate diluents.

As bipyridylium salt, use paraquat dichloride at 360 paraquats per liter? It was used at a concentration of ※※.

In operations using sodium chloride, it is a condensation product of 7 to 8 moles of ethylene oxide and p-nonylphenol and is called
A surfactant commercially available under the trade name of sapol"NX and a paraquat dichloride solution were mixed at a ratio of 4 parts of baraquat per 1 part of sapol"NXI and sprayed as a homogeneous mixture.

The products obtained in the two operations were homogeneous, free-flowing, non-scattering granules with an average particle size of 1-2 mm.

The operating conditions are shown in Table ①.

In addition, the analytical values and yield of the obtained product are shown in Table 2.

[Brief explanation of the drawing]

The drawing is a block diagram of an apparatus for implementing the invention.

Claims (1)

[Claims] 1 introducing an aqueous solution of herbicidal bipyridylium diquaternary salt into a fluidized bed of solid diluent particles maintained at an elevated temperature;
A herbicidal herbicidal agent, characterized in that the bipyridylium salt aqueous solution is thereby rapidly evaporated to deposit the bipyridylium diquaternary salt on the solid diluent particles, and then the solid granular composition thus obtained is collected. A method for producing a solid granular herbicide composition containing bipyridylium diquaternary salt and a solid diluent.