JP2770893B2 - Anti-mouse microcapsules - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcapsule having excellent stability and comprising a cycloheximide as an active ingredient.

More specifically, the present invention has a small decrease in the potency of cycloheximide when it is applied to a required molded article by kneading, coating, etc., and is particularly excellent in heat resistance and pressure resistance showing stable activity over a long period of time. And a dense rat-proofing agent microcapsule.

[0003]

2. Description of the Related Art The number of rats in Japan is about 3% of the population.
It is estimated to be double, or more than 300 million, and the damage is enormous throughout the year. The main types of such damage to rats include packaging materials such as paper or cloth bags of rice and wheat flour and damage to cardboard cases for packaging various foods, and flexible polyvinyl chloride or rubber. Container damage, and communication materials related to computer and related communications, power, optical communication cables, signal cables, other electric wires and cables, nesting, urination and defecation inside the machine Disconnection, poor contact, corrosion of parts, etc., and in the agricultural sector, there is damage to crops, fruit trees, and plantations. Many rodenticides and rodent repellents have been developed to prevent such rat harm.
Each has achieved some results, but when these are applied to various materials, it is necessary to make direct contact with the materials that compose them, so the physical properties of the materials may be lost,
It was inevitable that the pollution caused new damage. In addition, these agents volatilize within a short period of time or are washed away by rainwater, and as a result, it has been difficult to maintain their effects over a long period of time.

On the other hand, microcapsules using a solid rodenticide as a core substance have been proposed in order to facilitate the consumption of rodenticides by rats and the like. It is effective only when it produces an effect, and cannot be applied to a type of repellent which emits an odor which rats and the like dislike and emits it.

By the way, 3- [2- (3,5-dimethyl-2-oxocyclohexyl) -2-hydroxyethyl] glutarimide, ie, cycloheximide, is known as one of the compounds having a rat repellent action. This mechanism of action is thought to be because rats extremely dislike the taste of cycloheximide, and once they experience this taste, they remember the odor and repel it with only a faint odor that cannot be detected by humans. Have been.

[0006] As an example of the use of this cycloheximide, the crystal is kneaded into polyvinyl chloride and used for coating a cable. In this case,
In addition to the inevitable loss in potency caused by destruction due to pressure during molding, heating or free hydrochloric acid contained in polyvinyl chloride, the bleeding of cycloheximide onto the surface layer of the cable coating that occurs over time causes the coating to escape from the cable. There is a drawback of falling off.

Another example of use is to dissolve the cycloheximide crystal in a solvent and apply it directly to the surface of the required article. However, when the article is left outdoors, the cycloheximide is dissolved in water. However, it has the drawback of being easily drained by rainwater and rapidly losing its rat-control effect.

[0008] Accordingly, there has been a demand for a rat-controlling agent which can impart heat resistance and exhibit a stable effect for a long period of time without deteriorating the murine repellent effect of cycloheximide.

[0009] In order to respond to such a demand, the present inventors first made a solution in which cycloheximide was dissolved in a solvent inert thereto was used as a core material and a micro solution containing a urea resin or a melamine resin as a wall film material. A capsule-type anti-rat agent was proposed (Japanese Patent Publication No. 3-20361). However,
Although this microcapsule-type anti-mouse agent is considerably more effective than conventional anti-mouse agents, in maintaining cycloheximide titer during molding and stability over a long period of time,
It was not satisfactory enough.

[0010]

DISCLOSURE OF THE INVENTION The present invention overcomes the drawbacks of the conventional rat-control agents containing cycloheximide as an active ingredient, and has excellent heat resistance, high compactness, and pressure resistance. The purpose of the present invention is to provide a rat-proofing agent microcapsule capable of exhibiting a stable effect over a long period of time with little decrease in the cycloheximide titer when kneaded or coated with the compound.

[0012]

The present inventors have conducted intensive studies on microcapsules containing cycloheximide as a core substance, and as a result, have found that a urea resin is used as a wall substance, and that the surface is treated with a water-soluble polyester. It has been found that the object can be achieved, and the present invention has been completed based on this finding.

That is, the present invention provides

Embedded image A solution prepared by dissolving cycloheximide represented by the formula (1) in an inert solvent as a core substance, and using a urea resin as a wall substance to treat the surface of the microcapsules with a water-soluble polyester. .

In the microcapsule of the present invention, it is necessary to use, as a core substance, a solution in which cycloheximide is dissolved in a solvent inert thereto.

As this solvent, a solvent which dissolves cycloheximide well but does not reduce its titer even when contacted with it is used. Particularly preferred solvents have a relatively high boiling point of 250 ° C. or higher, do not volatilize even when heated when microcapsules are formed or kneaded into various materials, and are also hydrophobic. Typical examples of such a solvent include phthalic acid diester, low molecular weight epoxy resin, and phosphoric acid triester.

Examples of the phthalic acid diester include dimethyl phthalate (bp 282 ° C.), diethyl phthalate (bp 298 ° C.), and dibutyl phthalate (bp 298 ° C.).
340 ° C.), diheptyl phthalate, dioctyl phthalate, di (2-ethylhexyl) phthalate, diisodecyl phthalate, dityl benzyl phthalate, ditridecyl phthalate, and the like. Examples of the low molecular weight epoxy resin include an epoxy resin having a molecular weight of 400 or less, for example, Epicoat 815, 816, 818 (both are trade names manufactured by Shell Chemical Co., Ltd.). Examples of the phosphoric acid triester include triphenyl phosphate,
There are tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate and the like. These may be used alone or as a mixture of two or more.

Next, the wall material of the microcapsule of the present invention must not reduce the efficacy of cycloheximide or dissolve in the above-mentioned solvent. The present inventors have conducted various studies on the premise of these conditions, and found that the urea resin conforms to these conditions, and that the surface of the wall film is coated with a water-soluble polyester, thereby providing more excellent heat resistance and pressure resistance. It was found that a highly dense product could be obtained. When a resin other than the urea resin, for example, gelatin, polyamide, polyurethane or the like is used, the loss rate of cycloheximide in the capsule during storage increases, and the rat-proof effect is significantly reduced.

To prepare a microcapsule in which the solution containing the cycloheximide of the present invention is used as a core material and the core material is coated with a wall material, a method known in the art of microcapsule production, for example, dissolving or dispersing cycloheximide. A polymerization reaction occurs at the interface between the two phases of the monomer soluble in the solvent and the monomer soluble in the dispersion medium forming the continuous phase to form a microcapsule wall film of the polymer, and cycloheximide is contained in the wall film. An interfacial polymerization method in which microcapsules are produced by using a combination of a hydrophobic monomer and a hydrophilic monomer to obtain microcapsules encapsulating a solution and utilizing the polymerization reaction at the interface, or a continuous phase or discontinuous The monomer is supplied from only one of the phases, and the polymerization reaction takes place at the interface, and the microcapsule wall film It can be carried out using a method such as an in situ method for forming, a coacervation method, a curing-in-liquid coating method (orifice method), a drying method in liquid, a spraying / granulating method, etc. Among the methods, the in situ method is particularly preferable.

Next, in Santu (in Situ)
An example of a preferred method for forming a wall film made of a urea resin by the method will be described. First, an aqueous solution of a substantially completely hydrolyzed styrene-maleic anhydride copolymer is prepared, and then an oxalic acid is added thereto. And a polycarboxylic acid such as citric acid, tartaric acid, trimellitic acid or the like is added to adjust the pH to 6 or less. By adding this dicarboxylic acid,
The aqueous solution of the styrene-maleic anhydride copolymer gradually thickens and has the highest viscosity in the pH range of 3.5 to 5.5 and the maximum emulsifying power. It is advantageous to add a dicarboxylic acid to the mixture.

The thus obtained aqueous solution of a substantially completely hydrolyzed styrene-maleic anhydride copolymer having a pH of 6 or less serves as an emulsifier and a catalyst for forming a wall film, and serves as an emulsifier. The polymer contributes as one component for forming the wall film.

Next, to the thus obtained aqueous solution of substantially completely hydrolyzed styrene-maleic anhydride copolymer having a pH of 6 or less, a solution prepared by dissolving cycloheximide as a core substance in the solvent is added. Emulsify or disperse by high-speed stirring or ultrasonic application. The amount of the core substance at this time is suitably about 5 to 50 times the weight of the styrene-maleic anhydride copolymer based on the weight.

On the other hand, an initial condensate is prepared by condensing a mixture of urea and its resorcinol in an amount of 30 to 50% by weight and formalin at a temperature of about 20 to 90 ° C. under alkaline conditions. At this time, the ratio of formaldehyde to the total amount of urea and resorcin is usually 1.5 to 1.5.
2.0.

Next, the thus prepared initial condensate is mixed with the above-mentioned core substance by emulsifying or dispersing it at pH 6
In addition to the following aqueous solution of substantially completely hydrolyzed styrene-maleic anhydride copolymer, it is added under acidic conditions of pH 3-7, usually at a temperature in the range of 40-90 ° C.
A wall film comprising a reaction product of the substantially completely hydrolyzed styrene-maleic anhydride copolymer and the precondensate around microparticles comprising the core substance by stirring for about 00 minutes. Are formed to obtain a microcapsule dispersion.

At this time, the amount of the precondensate to be used is selected in the range of 10 to 100 parts by weight per 10 parts by weight of the styrene-maleic anhydride copolymer in terms of solid content.

The wall material of the microcapsule thus formed has a functional group such as a carboxyl group derived from a hydrolyzate of a styrene-maleic anhydride copolymer and an amino group or a hydroxyl group derived from the precondensate. Since a group is present, in the present invention, a water-soluble polyester is further added to the microcapsule dispersion, and the surface of the wall film is subjected to a cross-linking treatment, so that the wall film is more excellent in heat resistance, pressure resistance, and tightness. It is assumed to be high.

The water-soluble polyester is obtained, for example, by polycondensing a dicarboxylic acid component, a diol component and a monomer having a hydrophilic group, and having a hydrophilic group such as a hydroxyl group, a carboxyl group or a sulfonic acid group at the molecular terminal. It has a reactive functional group and reacts with the functional group of the wall substance to crosslink the wall surface.

Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and phthalic acid, and aliphatic dicarboxylic acids such as adipic acid, succinic acid, sebacic acid and dodecane diacid. Examples of the components include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, bisphenol A, and the like.

Further, as the monomer having a hydrophilic group,
Examples thereof include dimethyl sodium 5-sulfoisophthalate and polyethylene glycol.

The effect of the water-soluble polyester can be exhibited with a small amount, and even if it is used in a predetermined amount or more, no further effect can be expected. Therefore, the water-soluble polyester is preferably added in an amount corresponding to the molecular terminal group corresponding to the functional group of the wall substance. According to the strength measurement results, the amount of the water-soluble polyester to be added is selected in the range of 2.5 to 25% by weight, preferably 5 to 20% by weight, particularly 7 to 15% by weight based on the solid content.

The crosslinking reaction with the water-soluble polyester proceeds by heating and drying the dispersion. In this case, it is advantageous to carry out the drying in such a manner that the water content after drying is reduced as much as possible. This drying temperature is 100-250 ° C.
, For example, using a spray dryer.

The concentration of cycloheximide in the cycloheximide solution used as the core substance in the microcapsule of the present invention is 1 to 20% by weight, preferably 3 to 20% by weight.
A range of 15% by weight is suitable.

The particle size of the microcapsules is as follows:
Although not particularly limited, it is usually selected within the range of 5 to 100 μm.

The anti-mouse agent of the present invention comprises the above-mentioned microcapsules, which can be used, for example, as described below.

(1) In general, synthetic resin processed products mainly composed of polyvinyl chloride, such as communication / power / optical communication cables,
Kneading and coating of furniture, building interior and exterior materials (walls, bran, etc.), flexible containers and packaging containers. (2) Impregnation and kneading of yarn in fiber processed products. (3) Impregnation of various tapes (paper, plastic),
Kneading, coating. (4) Kneading into various adhesives. (5) Kneading into sealants and other paste-like products. (6) Mixing into various paints. (7) Kneading into various pellets and compounds.

[0035]

The microcapsule of the present invention is obtained by modifying the surface of a microcapsule containing a cycloheximide solution as a core substance and a urea resin as a wall substance with a water-soluble polyester, and has an excellent heat resistance. It has a high density, high density and pressure resistance, and can exhibit a stable rat-proofing effect over a long period of time without being kneaded into a material or being coated with the cycloheximide titer.

[0036]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

The pressure resistance and heat resistance of the microcapsules were compared by performing a destruction test and a heat resistance test as follows. (1) Destruction test: A ram pump (full scale 100 kg) manufactured by Riken Seiki Co., Ltd. was used as a load device, and a stainless steel container having a diameter of 10 mm and a depth of 7 mm was used as a load container. Sample (primary particles of microcapsules)
After accurately weighing 05 g into a stainless steel container, applying a load for 20 minutes with a load device with a pressure lid,
Put the container and pressure lid into a 20 cc sample bottle. Next, 10 ml of tetrahydrofuran was added, and after applying ultrasonic waves for 5 minutes, the mixture was filtered with a membrane filter, cycloheximide eluted from the broken capsule into tetrahydrofuran was quantified by liquid chromatography, and the breaking ratio (average of three tests) was determined. , And the pressure resistance was evaluated.

(2) Heat resistance test: 0.024 g of a sample was accurately weighed into a 100 ml volumetric flask (0.03 g in Comparative Example 2), heated in a drier set at a predetermined temperature for a predetermined time, and then added to cycloheximide. The residual cycloheximide was quantified by an extraction method, the residual ratio was determined, and the heat resistance was evaluated.

Example 1 25 g of cycloheximide (trade name: Naramycin, manufactured by Tanabe Seiyaku Co., Ltd.) was dissolved in 225 g of dimethyl phthalate.
A liquid was prepared. Next, 234 g of a 4% by weight aqueous solution of 100% hydrolyzate of styrene-maleic anhydride copolymer
While stirring the aqueous solution, 16 g of a 30% by weight aqueous citric acid solution was gently added, and then the above solution A was added to 250 g of the aqueous solution to emulsify to prepare an O / W emulsion.

On the other hand, 27.3 g of urea and 9.2 g of resorcin were added to 57.3 g of a formalin solution adjusted to pH 9.0.
Was added all at once, and dissolved at 60 ° C. to prepare pale orange liquid B. Next, this B solution was mixed with the O /
The mixture was gradually added to the W emulsion while stirring, and reacted at 80 ° C. for 2 hours to obtain a 8% by weight cycloheximide-encapsulated microcapsule dispersion having a wall film composed of urea-resorcin-formaldehyde resin.

Next, 27.0 g of a 25% aqueous solution of a water-soluble polyester (having a solid content ratio of 10.0% to the wall material) was added to the dispersion.
% By weight) and spray dryer (inlet temperature 200
C., outlet temperature 95 ° C.) to produce rat-proofing agent microcapsules.

The load per cm ² was 6.4 kg, 12.7 kg, 19.1 kg, or 25.
The breaking rate was measured at 5 kg, and the results are shown in Table 1. Further, the residual ratio of cycloheximide at 50 ° C. and 100 ° C. was measured, and the results are shown in Tables 2 and 3.

Comparative Example In the same manner as in Example 1, an O / W emulsion A solution was prepared. Separately, 28.2 g of melamine was added to 72.4 g of a formalin aqueous solution adjusted to pH 9.0, and the mixture was heated to 70 ° C. and dissolved to prepare solution B.

Next, the solution B was added little by little to the solution A while stirring, and the mixture was reacted at 80 ° C. for 2 hours to form an 8% by weight cycloheximide-encapsulated micro-tube having a wall film composed of a melamine-formaldehyde resin. A capsule dispersion was obtained. This dispersion was dried in the same manner as in Example 1 to produce rat-proofing agent microcapsules.

The microcapsules thus obtained were subjected to a destructive test and a heat test at 50 ° C. and 100 ° C.
The results are shown in Tables 1, 2 and 3.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

Example 2 A solution of 25 g of cycloheximide (trade name: Naramycin, manufactured by Tanabe Seiyaku Co., Ltd.) was dissolved in 225 g of dimethyl phthalate.
A liquid was prepared. Next, 234 g of a 4% by weight aqueous solution of 100% hydrolyzate of styrene-maleic anhydride copolymer
While stirring the aqueous solution, 16 g of a 30% by weight aqueous citric acid solution was gently added, and then the above solution A was added to 250 g of the aqueous solution to emulsify to prepare an O / W emulsion.

On the other hand, 27.3 g of urea and 9.2 g of resorcin were added to 57.3 g of a formalin solution adjusted to pH 9.0.
Was added all at once, and dissolved at 60 ° C. to prepare a pale orange liquid B. Next, this B solution was mixed with the O /
Add gradually to the W-type emulsion while stirring, 80 ° C
For 2 hours to obtain a 8% by weight cycloheximide-encapsulated microcapsule dispersion having a wall film made of urea-resorcin-formaldehyde resin.

Next, a 25% by weight aqueous solution of a water-soluble polyester was added to the dispersion in an amount of 0 to 50% by weight based on the solid content of the wall material, and a spray drier (inlet temperature: 200 ° C., outlet: (Temperature 95 ° C.) to produce 9 kinds of rodent-proofing microcapsules having different water-soluble polyester contents.

Each of these microcapsules has 25.5k
Table 4 shows the results of a pressure resistance measurement test with a load of g as a destruction rate.

[0053]

[Table 4]

As is clear from this table, the addition of the water-soluble polyester reduces the destruction rate.
It is almost constant around 0% by weight. If this amount exceeds 25% by weight, poor drying is caused, and formation of microcapsules becomes difficult.

REFERENCE EXAMPLE 1 Three control cables each having a conductor having a number of wires of 7 and a core wire outer diameter of 3.5 mm covered with an insulating layer made of a polyvinyl chloride composition to a thickness of 1.0 mm were twisted. 1.0m thick on top
m protective layer and further thereon 100 parts by weight of polyvinyl chloride (average degree of polymerization 1300), dioctyl phthalate 50
Parts by weight, 5 parts by weight of a polymerized tin mercapto compound, 1 part by weight of lead stearate and 8% by weight of cycloheximide (hereinafter C)
HI) microcapsules (obtained in Example 1 and Comparative Example) containing 5 parts by weight of a rat-proof polyvinyl chloride composition (CHI content: 0.25% by weight) and a thickness of 0.1%. Coextrusion coating (simultaneous multi-layer extrusion coating, conditions: 160 ° C., 5 minutes) was carried out to a thickness of 5 mm to prepare a rat-proof polyvinyl chloride-coated cable.

For these, the CHI content was measured using a method based on the method for quantitatively determining cycloheximide in polyvinyl chloride specified in the Official Agricultural Chemicals Inspection Method. Table 5 shows the results.

[0057]

[Table 5] As can be seen from this table, the residual ratio of CHI after processing is remarkably higher for the microcapsules of the present invention.

Reference Example 2 From each cable obtained in Reference Example 1, a rat-proof coating layer was cut out, kept at 50 ° C., and the amount of CHI in the coating layer was measured for 6 months to check the storage stability. Table 6 shows the results.

[0059]

[Table 6] As can be seen from this table, the microcapsules of the present invention are also excellent in storage stability.

Reference Example 3 The cable obtained in Reference Example 1, which was kept at 50 ° C. for 6 months, and a cable to which no rat antimicrobial microcapsules were added were cut to a length of 30 cm to obtain samples. Each of the samples was treated with 3 male Wistar rats that had been fasted for 24 hours.
The animals were placed in a cage, left for 24 hours, and taken out to examine the state of food damage by the rats.

This experiment was repeated 10 times for each sample, and the degree of the damage was divided into five stages from intact (−), test wound (±) to wound (3+) where the core wire was exposed, and − and ±.
Were assigned to 3 points, 2 points to +, 1 point to 2+, and 0 points to 3+, and a total of 10 times was calculated. Then, the rejection rate (%) was defined as a percentage relative to the case of-or ±, that is, 30 points. The results are shown in Table 7.

[0062]

[Table 7] As can be seen from the table, the microcapsules of the present invention show almost complete repellency.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisano Higurashi 3-21-271-2 Nakano Sanno, Hachioji-shi, Tokyo (58) Field surveyed (Int. Cl. ⁶ , DB name) A01N 25/28 CA (STN )

Claims (1)

(57) [Claims] (1) Formula (1) A microcapsule comprising a solution obtained by dissolving cycloheximide represented by the formula (1) in an inert solvent as a core material and a surface of a microcapsule comprising a urea resin as a wall material, treated with a water-soluble polyester;