WO2020021314A1

WO2020021314A1 - Concentrated suspensions of copper salicylate and preparation process thereof

Info

Publication number: WO2020021314A1
Application number: PCT/IB2018/055611
Authority: WO
Inventors: Silvia Mormile; Paolo Bellandi; Giampaolo Zanardi; Claudio DACARRO; Elisa GALIMBERTI
Original assignee: Isagro SpA
Current assignee: Isagro SpA
Priority date: 2018-07-26
Filing date: 2018-07-26
Publication date: 2020-01-30
Anticipated expiration: 2021-01-26

Abstract

Concentrated suspensions of copper salicylate having a copper concentration higher than 5% by weight are described, in addition to a process for their preparation and their use as fungicides and for the control of phytopathogenic bacteria.

Description

CONCENTRATED SUSPENSIONS OF COPPER SALICYLATE AND PREPARATION PROCESS THEREOF

The present invention relates to concentrated suspensions of copper salicylate and the preparation process thereof.

STATE OF THE ART

Salicylate acid is a derivative of a carboxylic acid, extracted from the bark of willow trees, composed of a phenolic ring and a carboxylic group. The simultaneous presence of an acid function given by the carboxylic group and a phenolic group gives this molecule remarkable anti-rheumatic properties, in addition to anti-inflammatory and antiphlogistic properties.

Furthermore, in the agricultural field, it has been demonstrated that salicylic acid is able to control different phytopathogens through the induction of defense systems naturally present in plants, which are activated only after entry of the pathogen.

The Applicant has previously found that copper salicylate, possibly combined with other products, is characterized by an optimum fungicidal effectiveness, as described in patent application W02005/094580.

In addition, patent application WO2017/109694 reports that copper salicylate in some specific crystalline forms can he validly used for controlling plant bacteria, without causing undesirable effects of phytoto icity.

These crystalline forms can be prepared as specified in WQ2010/076038, in Wuhan University Journal of Natural Sciences, 2003, 425-427 or in Nippon Kagaku Kaishi, 1979, 4, 502-505.

Numerous formulations containing copper salts are known in the art for use in the agrochemical field. These formulations may be in the form of solid or liquid preparations, or in the form of suspensions of solids in liquids.

For correct use, the formulations must be able to dissolve, or disperse, or must give rise to stable emulsions when diluted in appropriate volumes of water. These emulsions are, in turn, applied on the crops or on the soil in which the crop is grown, before or after sowing or germination. Numerous agropharmaceuticals are validly used in the form of concentrated suspensions (SC), a specific type of liquid formulation in which the finely ground active ingredient is suspended in water with the addition of particular surfactants such as welting agents, dispersants, rheology modifiers, defoamers and biocides, which allow- its stability to be improved and thus make the active ingredient more suitable for agricultural use.

There are numerous advantages of concentrated suspensions: a reduced environmental impact due to the absence of organic solvents, in addition to greater safety for the operator in applying the product to the ground.

However, when copper salicylate is prepared and isolated according to one of the methods known in the ait described above and subsequently formulated, or when it is used as a slurry ready for the formulation, it is not possible to obtain a concentrated suspension having a concentration, expressed as a copper content, higher than 5% by weight.

For concentrations higher than 5% by weight, in fact, the concentrated suspension is excessively viscous and shows phenomena of physical instability, such as flocculation or aggregation.

Consequently, in the agrochemical field, the need is strongly felt for stable, liquid formulations which, having a higher concentration, allows a reduction in the volume of the formulation to be used for reaching the dose of use in a single treatment, with a consequent reduction in production, transportation and disposal costs.

DESCRIPTION

The Applicant has surprisingly found a process for the preparation of concentrated suspensions containing copper salicylate having a concentration of copper higher than 5% by weight, with respect to the total weight of the suspension.

The suspensions obtained by this process are stable over time, with no thickening phenomena and are easy to pour and suitable for use in the agricultural field.

A first object of the present invention therefore relates to a process for the preparation of concentrated suspensions containing copper salicylate having a concentration of copper higher than 5% by weight, with respect to the total weight of the suspension, comprising the following steps:

a) a copper compound is added to an aqueous suspension of salicylic acid, possibly in the presence of an inorganic base;

b) the suspension obtained in step (a) is left under stirring for a time ranging from 1 to 4 hours at a temperature ranging from 40 to l00°C;

c) co-formulants are added to the suspension obtained in step b); and d) the suspension thus obtained is subjected to grinding up to an average particle size of less than a 4 pm;

said process being characterized in that steps a), b), c) and d) are carried out in direct sequence, without isolating any intermediate.

As is well known to the skilled persons in the field, the grinding step d) is carried out at a controlled temperature, preferably at temperatures ranging from 15 to 45°C. This grinding allows a particle-size of the particles preferably equal to or less than 4 pm for Dv 50 and equal to or less than 12 pm for Dv 90, to be reached.

The term“Dv 50” represents the value of the average diameter below which there is 50% of the particles.

The term“Dv 90” represents the value of the average diameter below which there is 90% of the particles.

The fundamental aspect of the process according to the present invention is therefore specifically linked to the implementation of steps a), b), c) and d) in direct sequence, without isolating any intermediate: the product obtained in step a) is directly subjected to step b), the product resulting from step b) is the starting material of step c) and the product resulting from step c) is subjected to step d), all without any isolation and/or purification step of intermediates.

More specifically, therefore, in step a) of the process according to the present invention, copper salicylate is prepared by the addition of a copper compound to an aqueous suspension of salicylic acid. Said copper compound is preferably selected from copper hydroxide, copper chloride and copper sulfate. If copper sulfate or copper chloride is used, an inorganic base preferably selected from hydroxides of alkaline metals, more preferably selected from sodium hydroxide, potassium hydroxide and ammonium hydroxide, must be added. Said inorganic base is added to the resulting solution in a molar quantity ranging from 1.5 to 2.5, preferably equal to about 2, with respect to the quantity of copper compound used. In step b) of the process according to the present invention, the suspension obtained in step (a) is left under stirring for a time ranging from 1 to 4 hours, preferably for about 2 hours, at a temperature ranging from 40 to l00°C.

According to a preferred aspect, the suspension is left under stirring at a temperature ranging from 60°C to 80°C, preferably about 70°C, leading to the formation of the crystalline form II of copper salicylate, described in Wuhan University Journal of Natural Sciences, 2003, 425-427 and WO2017/109694, incorporated herein as reference.

Said copper salicylate is not isolated and purified according to methods known in the art, such as precipitation or crystallization, but is used as such as slurry ready for the subsequent formulation, in step c) of the process according to the present invention.

The reaction medium is preferably brought to a temperature ranging from room temperature to 40°C and appropriate co-formulants are added for the preparation of the concentrated suspension.

The addition of these coformulants has the advantage of rendering the reaction mixture considerably fluid and therefore easily transferable to the subsequent processing step.

The preparation of the above-mentioned concentrated suspension is carried out according to known methods, mixing the components in the desired ratios and in any order.

In step d) of the process according to the present invention, the resulting concentrated suspension is subjected to grinding until an average particle size of less than 4 pm has been reached.

The formulation process according to the present invention can also be used for the preparation of concentrated suspensions containing copper salicylate in a quantity lower than 5% by weight of copper, with respect to the total weight of the suspension, providing, also in this case, a stable and pourable formulation and therefore suitable for use in the agricultural field.

A further object of the present invention relates to a concentrated suspension comprising:

i) copper salicylate in a quantity higher than 5% by weight of copper with respect to the total weight of the suspension;

ii) one or more dispersing agents in a quantity ranging from 1% to 10% by weight with respect to the total weight of the suspension, and optionally

iii) one or more wetting agents in a quantity ranging from 1% to 5% by- weight with respect to the total weight of the suspension.

Said copper salicylate is present in the concentrated suspension of the invention in a quantity higher than 5% by weight of copper, preferably in a quantity ranging from 6% to 12% by weight of copper, with respect to the total weight of the concentrated suspension.

Said one or more dispersing agents are selected from non-ionic surfactants, anionic surfactants and mixtures thereof.

The non-ionic surfactants used as dispersing agents are preferably selected from etho-propoxylated block copolymers, acrylic polymers, polycarboxylates, methyl oleyl taurates, ethoxylated tristyrylphenols, etho-propoxylated tristyryiphenois, alkyl polyglucosides and mixtures thereof.

The anionic surfactants used as dispersing agents are preferably selected from ethoxylated tristyrylphenol phosphates, ethoxylated Iristyrylphenol sulfates, condensed alkyl-naphthalene sulfonates, lignosulfonates and mixtures thereof. They are more preferably selected from condensed alkyl-naphthalene sulfonates and lignosulfonates.

In the concentrated suspension according to the present invention, said one or more dispersing agents are present in a quantity ranging from 1% to 10% by- weight, preferably from 1.5% to 6% by weight, more preferably in a quantity equal to about 5% by weight, with respect to the total weight of the above- mentioned concentrated suspension. Furthermore, the above-mentioned concentrated suspension preferably does not contain wetting agents unlike concentrated suspensions traditionally used in agriculture.

If necessary, however, one or more wetting agents can be added to the concentrated suspension of the invention, in a quantity ranging from 1 % to 5% by weight, preferably from 1.5% to 3% by weight, more preferably equal to about 2% by weight, with respect to the total weight of the concentrated suspension.

Said one or more wetting agents are selected from non-ionic surfactants, anionic surfactants and mixtures thereof, preferably said one or more wetting agents are non-ionic surfactants.

The non-ionic surfactants used as wetting agents are preferably selected from sorbitan esters and ethoxy fated fatty alcohols.

The anionic surfactants used as wetting agents are preferably selected from sulfo succinates and sulfonated alkyl naphthalene and their salts, more preferably they are sulfosuccinates and their salts, even more preferably a sodium salt of sulfo succinate.

As is well known to skilled persons in the field, the concentrated suspensions according to the present invention can also comprise further surfactants and co- formulants, such as rheology modifiers, defoamers and biocides/preservatives. Further compounds can also be optionally added to the above-mentioned concentrated suspensions to improve their biological activity.

The complement to 100 consists of the solvent, i.e. water.

The concentrated suspensions according to the present invention also show a high fungicidal and bactericidal activity and do not show any phytotoxicity towards the application crops.

A further object of the present invention therefore relates to the use of the above- mentioned concentrated suspensions as fungicides and for the control of phytopathogenic bacteria.

The concentrated suspensions according to the present invention can be applied to any aerial part of the plant, such as for example leaves, stems and branches. Examples of crops of interest are fruit trees, horticultural crops and extensive crops such as rice and wheat.

The quantity of formulation to be applied for obtaining the desired effect can vary depending on various factors such as, for example, the crop, the climatic conditions, the characteristics of the soil, the application method, etc.

Overall doses of formulations ranging from 0.5 1 to 12 1 per hectare of agricultural crop generally provide a sufficient activity.

The following examples are now provided for a better illustration of the invention, which should be considered as being illustrative and non-limitative of the same. EXPERIMENTAL PART EXAMPLE 1

Preparation of a concentrated suspension of copper salicylate containing 10% of copper (with wetting agents)

Procedure - Reaction step

The reaction was carried out in a glass reactor having a useful volume of 30 litres, equipped with an efficient stirring system, for example with a blade or propeller, and a discharge valve on the bottom. The system is also provided with a heating and cooling system consisting of an outer jacket in which a suitable fluid circulates coming from a circulation thermostat. The temperature of the reaction mass was measured by means of a thermometer. A water-cooled condenser intercepted the vapours leaving the system.

Water (6.75 1) and salicylic acid (3,000 g) were initially charged into the reactor; the resulting suspension was kept under stirring and progressively heated to about 70°C.

Solid technical copper hydroxide (2,255 g) was subsequently added to the same suspension, over a time period of 10-20 minutes.

At the end of the addition, the resulting green-coloured suspension was stirred in continuous at the same temperature of about 70°C for a further 2 hours.

The mixture was then cooled inside the reactor to an internal temperature below 40°C. The necessary co-formulants, indicated in the following 'Fable 1 , were then added to and homogeneously incorporated in the mixture in a quantity of about 1 320 g. The fluid thus obtained was discharged from the reactor through the valve at the bottom, and transferred to the grinding step.

The preparation of the concentrated suspension was completed with the addition of biocide and thickening agent and the slurry thus obtained was ground in a ball mill to obtain an average particle size less than or equal to 4 pm.

An example of a composition thus obtained is indicated in Table 1.

Table 1

Agnique PG1805-G is an alkyl polyglucoside

Bretax C is ligno sulfonate calcium salt

Rhodasurf ID/5 is a C9-C11 alcohol, rich in C10 ethoxylate

Defoamer DB310 is a polydimethylsiloxane

Amebact C is 2,2’,2”-(hexahydro-l,3,5-triazin— l,3,5-triyl)triethanol

Rhodopol G is a xanthan gum.

EXAMPLE 2 Preparation of a concentrated suspension of copper salicylate containing 10% of copper (without wetting agents)

The same experimental procedure was repeated as described in Example 1, without adding wetting agents to the slurry containing copper salicylate, with the components indicated in the following Table 2.

Table 2

Amepon DP is condensed polynaphthalenesulfonate

Bretax C is ligno sulfonate calcium salt

Defoamer DB310 is a polydimethylsiloxane

Amebact C is 2,2’,2”-(hexahydro-l,3,5-triazin— l,3,5-triyl)triethanol

Rhodopol G is a xanthan gum.

The formulations of Examples 1-2 were subjected to the accelerated stability test (according to Cipac MT 46.1 ) which aims at accelerating the aging of the product by heating. This test serves to mimic the stability of a specific formulation after 2 years of storage at room temperature.

The procedure is as follows: a certain amount of formulation (for example 500 ml) is introduced into a hermetically sealed container and left in an oven at 54°C for 14 days. After this time period, the container is removed from the oven and is left to return to room temperature. It is then verified that the formulation has not undergone separation of the phases or other phenomena of physical instability such as flocculation, aggregation, crystalline growth or increase in viscosity.

Claims

1. A process for the preparation of concentrated suspensions containing copper salicylate having a concentration of copper higher than 5% by weight, with respect to the total weight of the suspension, comprising the following steps: a) a copper compound is added to an aqueous suspension of salicylic acid, possibly in the presence of an inorganic base; b) the suspension obtained in step (a) is left under stirring for a time ranging from 1 to 4 hours at a temperature ranging from 40 to l00°C;

2. The process according to claim 1, wherein in step a), the copper compound is selected from copper hydroxide, copper chloride and copper sulfate.

3. The process according to any of the previous claims, wherein the copper compound is selected from copper chloride and copper sulfate, in the presence of an inorganic base selected from hydroxides of alkaline metals, preferably from sodium hydroxide, potassium hydroxide and ammonium hydroxide, said inorganic base being added to the solution in a molar quantity ranging from 1.5 to 2.5, preferably equal to about 2, with respect to the quantity of copper compound used.

4. The process according to one or more of the previous claims, wherein in step b), the suspension is left under stirring for a time ranging from 1 to 4 hours, preferably for about 2 hours, at a temperature ranging from 40 to l00°C.

5. The process according to one or more of the previous claims, wherein in step b), the suspension is left under stirring at a temperature ranging from 60 to 80°, preferably about 70°C.

6. The process according to one or more of the previous claims, wherein the grinding step is carried out up to a particle size of the particles, preferably equal to or less than 4 pm for Dv 50 and equal to or less than 12 pm for Dv 90.

7. The process according to one or more of the previous claims, wherein the grinding step is carried out at a temperature ranging from l5°C to 45 °C.

8. A concentrated suspension comprising:

i) copper salicylate in a quantity higher than 5% by weight, preferably from 6% to 12% by weight, of copper with respect to the total weight of the suspension;

ii) one or more dispersing agents in a quantity ranging from 1% to 10% by weight, preferably from 1.5% to 6% by weight, more preferably in a quantity equal to about 5% by weight, with respect to the total weight of the suspension, and optionally

iii) one or more wetting agents in a quantity ranging from 1% to 5% by weight, preferably from 1.5% to 3% by weight, more preferably 2% by weight, with respect to the total weight of the suspension.

9. The suspension according to claim 8, wherein one or more dispersing agents are selected from non-ionic surfactants, anionic surfactants and mixtures thereof, the non-ionic surfactants being preferably selected from etho- propoxylated block copolymers, acrylic polymers, polycarboxylates, methyl oleyl taurates, ethoxyiated tristyrylphenols, etho-propoxylated tristyryiphenols, alkyl polyglucosides and mixtures thereof, the anionic surfactants being preferably selected from ethoxyiated tristyryl phenol phosphates, ethoxyiated tristyrylphenol sulfates, condensed alkyl -naphthalene sulfonates, lignosulfonates and mixtures thereof, more preferably condensed alkyl-naphthalene sulfonates and lignosulfonates.

10. The suspension according to one or more of claims 8 and 9, wherein one or more wetting agents are selected from non-ionic surfactants, anionic surfactants and mixtures thereof, they are preferably non-ionic surfactants, said non-ionic surfactants being preferably selected from sorbitan esters and ethoxyiated fatty alcohols.

11. The suspension according to claim 10, wherein the anionic surfactants are selected from sulfosuccinates and sulfonated alkyl naphthalene and their salts, they are more preferably sulfosuccinates and their salts, even more preferably a sodium salt of sulfo succinate

12. Use of a concentrated suspension according to any of claims 8-11 as fungicides and for the control of phytopathogenic bacteria, preferably by application to the crop via the leaves.