JP2007290891A - Method for manufacturing resin-coated granular fertilizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a resin-coated granular fertilizer with suppressed initial elution of fertilizer components and controlled elution of fertilizer components. <P>SOLUTION: This method for manufacturing the resin-coated granular fertilizer comprises alternately coating mineral powder and a polyol compound liquid at room temperature by each 1-5 layers on the surface of granular fertilizer whose water absorption is ≥0.01 g-water/g-fertilizer at room temperature thereby making the water absorption at room temperature to ≥0.001 g-water/g-fertilizer and less than 0.01 g-water/g-fertilizer, and then coating the surface with a resin coating material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a resin-coated granular fertilizer. Specifically, the present invention relates to a method for producing a resin-coated granular fertilizer in which initial elution of fertilizer components is suppressed and elution of fertilizer components is controlled.

In recent years, due to the aging of agricultural workers, the decrease in the number of employed workers, and the increase in part-time farmers, it is more labor-saving and the fertilizer effect-type resin-coated granular fertilizer that keeps elution of fertilizer components as the plant grows for a predetermined period Is required. Among them, a resin-coated granular fertilizer in which initial elution of fertilizer components is suppressed and elution of fertilizer components is controlled is desired.
As a method for producing a resin-coated granular fertilizer with few coating defects for controlling the elution of fertilizer components, generally, a method of repairing a coating defect portion by increasing the amount of the resin coating is taken. However, this method has a problem that the amount of fertilizer component is reduced and the cost is high.

In addition, as a method for producing a coated granular fertilizer with few coating defects, when the coated granular fertilizer is produced by coating the surface of the granular fertilizer with a coating material containing a synthetic resin as a main component, the circularity coefficient [(4π × particle (Projected area) / (length of contour of particle projection) ² ] is known to be a method using a granular fertilizer having a value of 0.7 or more (see Patent Document 1).
However, the effect of the fertilizer type is greater than the influence of the circularity on the elution performance of the fertilizer component, and even if the circularity coefficient of the granular fertilizer is close to 1, the elution performance is not necessarily improved. Therefore, there is a demand for a method for producing a resin-coated granular fertilizer in which the initial elution is small and the elution of fertilizer components is controlled.
Japanese Patent Laid-Open No. 10-158084

  The present invention provides a method for producing a resin-coated granular fertilizer in which initial elution of fertilizer components is suppressed and elution of fertilizer components is controlled, that is, the elution rate of fertilizer components is controlled, and elution of fertilizer components lasts for a predetermined period. It is to provide.

  In view of such circumstances, the present inventors have intensively studied a method for producing a resin-coated granular fertilizer in which the initial elution of the fertilizer component is suppressed and the elution of the fertilizer component is controlled. It is found that the larger the water absorption amount, the smaller the water absorption amount, and the smaller the water absorption amount, and the surface of the granular fertilizer is alternately changed to mineral powder and a liquid polyol compound at room temperature (20 to 30 ° C., hereinafter the same). If it is coated with ˜5 layers, it becomes possible to easily reduce the amount of water absorption. By this method, the amount of water absorption of the granular fertilizer at room temperature is 0.001 g-water / g-fertilizer. After making less than g-fertilizer, it was found that by coating the surface with a resin coating material, resin-coated granular fertilizer in which the elution of the fertilizer component was suppressed and the elution of the fertilizer component was controlled was obtained. Departure The has been completed.

  That is, the present invention coats the surface of granular fertilizer having a water absorption of 0.01 g-water / g-fertilizer or more at room temperature alternately with 1-5 layers of mineral product powder and liquid polyol compound at room temperature. The amount of water absorption at room temperature is 0.001 g-water / g-fertilizer more than 0.01 g-water / g-fertilizer and then the surface is coated with a resin coating. It is a manufacturing method of resin-coated granular fertilizer.

  By the method of the present invention, it is possible to produce a resin-coated granular fertilizer in which initial elution is suppressed and elution of fertilizer components is controlled, and its industrial utility value is very large.

The granular fertilizer used in the present invention is a granular material containing a fertilizer component, and has a water absorption of 0.01 g-water / g-fertilizer or more at room temperature.
The fertilizer component is a component containing various elements such as nitrogen, phosphorus, potassium, silicon, magnesium, calcium, manganese, and boron that are applied to the soil to provide nutrients in plant cultivation such as paddy rice. Specific examples include urea, ammonium nitrate, ammonium nitrate, ammonium nitrate, ammonium sulfate, ammonium phosphate, sodium nitrate, calcium nitrate, potassium nitrate, lime nitrogen, formaldehyde processed urea fertilizer (UF), acetaldehyde processed urea fertilizer (CDU), Nitrogenous fertilizers such as isobutyraldehyde processed urea fertilizer (IBDU) and guaneaure urea (GU), superphosphate lime, heavy superphosphate lime, molten phosphorus fertilizer, humic phosphate fertilizer, calcined phosphorus fertilizer, heavy calcined phosphorus, bitter Soil perphosphate, ammonium polyphosphate, potassium metaphosphate, calmetaphosphate Phosphoric fertilizers such as humic, bitter phosphate, ammonium sulfate, potassium phosphate, ammonium phosphate, potassium chloride, potassium sulfate, potassium sulfate, potassium sulfate, potassium bicarbonate, potassium phosphate, etc. Fertilizers, siliceous fertilizers such as calcium silicate, magnesium fertilizers such as magnesium sulfate and magnesium chloride, calcium fertilizers such as quick lime, slaked lime and calcium carbonate, manganese fertilizers such as manganese sulfate, sulfated manganese manganese, and mineral manganese, Nitrogen-phosphoric acid, nitrogen-kari, and ordinary fertilizers (including complex fertilizers) defined by the fertilizer control law such as borate fertilizers such as acids and borates, and / or combinations of these Phosphoric acid-Kari two-component system, nitrogen-phosphoric acid-Kari three-component system, or plants such as magnesium, manganese, boron, etc. It includes granular fertilizer which contains the necessary elements for growth.
The particle size of the granular fertilizer is not particularly limited, but is usually in the range of 1 to 15 mm and preferably in the range of 2 to 5 mm from the viewpoint of production.

  Examples of the mineral powder used in the present invention include talc, kaolin, diatomaceous earth, activated white clay, quartz sand, bentonite, and phyllite. Of these, talc and lozenges are preferably used.

  The coating amount of one layer of mineral product powder is usually in the range of about 0.1 to 2% by weight based on the granular fertilizer. When the coating amount of one layer exceeds about 2% by weight, the rate of attachment to the granular fertilizer decreases, and powdering increases with this, which is not preferable because the operability deteriorates. The amount of coating and the number of coatings are appropriately adjusted according to the amount of water absorbed by the granular fertilizer to be used. For example, when the water absorption amount of the granular fertilizer is small, the coating process is sufficient once, and when the water absorption amount is large, the coating process is repeated a plurality of times, for example, 2 to 5 times until the predetermined water absorption amount is reached. It is. The coating method is not particularly limited, and methods known in the art can be applied. Generally, a method is used in which a granular fertilizer is supplied to a rolling-type rotating cylinder, a rotating dish, or the like, and a mineral product powder is added and mixed to the rolling while being rolled.

  The polyol compound that is alternately coated with the mineral product powder is an amino alcohol, amine, or the like that is liquid at room temperature as an initiator, and an aliphatic alcohol such as propylene glycol or trimethylol propane and ethylene oxide or propylene oxide. Polyether polyols obtained by addition, polyether type polyols such as polytetramethylene ether glycol obtained by polymerizing tetrahydrofuran, natural fats and oils having hydroxyl groups such as Isano oil and castor oil, polyhydric alcohols, polyether polyols and carboxyls Examples thereof include polyester type polyols obtained by a method of reacting an acid compound, among which polyether polyols are preferably used.

  The coating amount of one layer of a polyol compound that is liquid at room temperature is usually in the range of about 0.1 to 2% by weight with respect to the granular fertilizer. If the coating amount of one layer exceeds about 2% by weight, the rate of attachment to the granular fertilizer will decrease, and with this, the liquid will become excessive and adhesion of the granular fertilizer will easily occur. This is not preferable because the properties deteriorate. The amount of coating and the number of coatings are appropriately adjusted according to the amount of water absorbed by the granular fertilizer to be used, as in the case of the mineral product powder. The coating method is not particularly limited, and methods known in the art can be applied in the same manner as the mineral powder. In general, a method is used in which a granular fertilizer coated with mineral product powder is rolled and sprayed, mixed and coated with an apparatus such as a rolling type rotating cylinder or rotating dish.

  Resin coating material for coating the surface of a granular fertilizer coating treated with a water absorption amount at room temperature of 0.001 g-water / g-fertilizer or more and less than 0.01 g-water / g-fertilizer by the above treatment method As for, thermosetting resin is mainly used. As the thermosetting resin, an alkyd resin, a urethane resin or the like is used, and among them, a urethane resin is preferably used. The urethane resin is produced by three-dimensional crosslinking by a reaction between a polyisocyanate compound and a polyol compound. Further, two or more polyisocyanate compounds and / or two or more polyol compounds can be mixed and used.

  Examples of the polyisocyanate compound include toluene diisocyanate (hereinafter sometimes abbreviated as TDI), diphenylmethane diisocyanate (sometimes abbreviated as MDI), naphthalene diisocyanate, tolidine isocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diene. An isocyanate etc. can be mentioned and these mixtures can be used as needed. Among these, MDI, TDI or oligomers derived from these (polymeric MDI, polymeric TDI, etc.) are preferably used.

  As the polyol compound to be reacted with the polyisocyanate compound, for example, amino alcohol, amine and the like as described above are used as a starting material, and an aliphatic alcohol such as propylene glycol and trimethylolpropane is polyadded with ethylene oxide and propylene oxide. Polyether polyol obtained, polyether type polyol such as polytetramethylene ether glycol obtained by polymerizing tetrahydrofuran, natural fats and oils possessing hydroxyl groups such as Isano oil and castor oil, polyhydric alcohol, polyether polyol and carboxylic acid compound Examples thereof include polyester-type polyols obtained by a method such as reaction.

  The equivalent ratio of the NCO group derived from the polyisocyanate compound to be used and the OH group derived from the polyol compound, so-called NCO / OH, is usually adjusted between 0.9 and 1.2.

  Examples of the catalyst added for the purpose of accelerating the curing of the urethane resin raw material include triethylenediamine, N-methylmorpholine, N, N-dimethylmorpholine, diazabicycloundecene, imidazole, ethylmethylimidazole, diazabicyclo. Amine catalysts such as octane, 2,4,6, -tris (dimethylaminomytyl) phenol, ammonia derivatives such as urea, alkaline compounds such as sodium hydroxide and potassium hydroxide, organic compounds such as dibutyltin laurate and dibutyltin malate A tin compound is mentioned. Of these, amine-based catalysts are preferably used. The amount of these catalysts is usually about 0.05 to 5% by weight based on the total weight of the polyisocyanate compound and the polyol compound.

  The amount of the resin coating material is not particularly limited, and is appropriately adjusted according to a desired elution rate and elution period. Usually, it is performed within a range of 3 to 15% by weight with respect to the granular fertilizer.

  The method for coating the resin coating material is not particularly limited, and methods known in the art can be applied. In general, the water absorption amount at room temperature is 0.001 g-water / g-fertilizer or more and 0.01 g- There is used a method in which a liquid thermosetting resin is added to and coated with a granular fertilizer coating treated with less than water / g-fertilizer and rolled, followed by thermal curing and coating.

The reason for obtaining a resin-coated granular fertilizer in which initial elution is suppressed and elution of fertilizer components is controlled by the method of the present invention is not clear, but is presumed as follows.
In the conventional resin coating method, the state of the resin coating becomes non-uniform between the portion of the granular fertilizer having pores and the portion having no pores. When the pore size is large and the amount of water absorption is large, the state of the coating is further non-uniform, so that elution control according to the amount of coating becomes impossible, and elution occurs every time the amount of water absorption of the granular fertilizer used differs. It becomes unstable and it becomes difficult to control elution according to the coating amount.
On the other hand, in the method of the present invention, the mineral powder added first is taken into the pores, and then the liquid polyol compound is further taken into the pores at room temperature, and the pores are filled. When the pores are large, this is repeated several times to completely fill the pores, and as a result, a granular fertilizer with very few pores can be obtained. When coating the granular fertilizer thus obtained with a resin solution, the resin solution can be layered without being taken into the pores, so that the film thickness becomes uniform, and therefore the coating Elution control according to the amount becomes possible.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
In addition, unless otherwise indicated, all the parts and% in an Example show a weight part and a weight percentage.

Moreover, the water absorption amount and the elution amount of the fertilizer component were measured by the following methods.
(1) Measurement of water absorption:
At room temperature, put 300g of granular fertilizer into a commercial bread granulator (container: stainless steel, container dimensions: 240mmφ x 75mm, tilt angle: 45 degrees, rotation speed: 50rpm), and use an electric burette while rolling. Add water from the top of the rolling granular fertilizer at an addition rate of 0.2 g / sec, add until the granular fertilizer stops rolling, measure the amount of water until it stops rolling, It was.
(2) Measurement of fertilizer component elution amount:
5 g of resin-coated granular fertilizer to be measured was put into each of a plurality of 100 ml glass tubes with stoppers, 100 ml of water was added and immersed, stoppered and placed in a thermostatic bath at 25 ° C.
At predetermined intervals, the glass tube was taken out of the thermostat, the solution was filtered with chemical filter paper, and the fertilizer components eluted in water were quantitatively analyzed, and the elution amount (%) was calculated.

Example 1
(1) Manufacture of a coated processed product of granular fertilizer having a water absorption at room temperature of less than 0.01 g-water / g-fertilizer:
At room temperature, 20 kg of granular sulfuric acid (water absorption at room temperature: 0.082 g-water / g-fertilizer, average particle size 3.5 mm) was charged into a rolling type coating apparatus. The rotating part of the coating apparatus was rotated at 20 to 30 rpm, and the charged granular sulfuric acid was brought into a rolling state. Mineral powder talc [149 μm (100 mesh) pass product, the same applies hereinafter] 200 g was gradually added from the upper part of the animal to be coated. Next, 200 g of a branched polyol polyether of a polyol compound (Sumiphen (registered trademark) TM, manufactured by Sumitomo Bayer Urethane Co., Ltd.) was spray-applied from the upper part of the animals and coated. The amount of water absorption of the obtained coated processed product was 0.046 g-water / g-fertilizer. Since the water absorption amount is not less than 0.01 g-water / g-fertilizer, the coated product is further rolled using the same apparatus and the same conditions as above, while 200 g was gradually added for coating. Next, 200 g of the branched polyether polyol was spray-applied from the upper part of the animal and coated. The amount of water absorption of the resulting coated product was 0.007 g-water / g-fertilizer.

(2) Production of resin-coated granular fertilizer:
The surface of the coated water treated product of 0.007 g-water / g-fertilizer obtained in (1) above was coated with a urethane resin by the following method to produce a resin-coated granular fertilizer. The coating amount of the urethane resin on the coated product was 4%.
At room temperature, 208.8 g of branched polyether polyol (Sumiphen (registered trademark) TM, manufactured by Sumitomo Bayer Urethane Co., Ltd.) and 4 g of 2,4,6-tris (dimethylaminomethyl) phenol as a curing catalyst were added to a polyol mixing tank, and 30 The mixture was stirred for a minute to obtain 212.8 g of a mixture (hereinafter referred to as a mixture A).
10 kg of the coated product was charged in a rolling type coating apparatus capable of controlling the temperature. The rotating part of the coating device was rotated at 20 to 30 rpm, and the charged coated product was brought into a rolling state. While maintaining the temperature of the coated product to 70 to 75 ° C., 187.2 g of polymeric MDI (Sumijoule (registered trademark) 44V10, manufactured by Sumitomo Bayer Urethane Co., Ltd.) as a polyisocyanate compound and 212.8 g of mixture A were mixed. The liquid uncured urethane resin composition obtained in this manner was gradually added and coated while being thermally cured. The time required for this coating treatment was about 28 minutes.
With respect to the resin-coated granular fertilizer having a urethane resin coating amount of 4% obtained in this manner, the fertilizer component elution performance was measured. The results are shown in Table 1.

Example 2
The surface of the coated product with a water absorption of 0.007 g-water / g-fertilizer obtained in Example 1 was coated with a urethane resin by the following method to produce a resin-coated granular fertilizer. The coating amount of the urethane resin with respect to the coated product was 8%.
Add 417.7 g of branched polyether polyol (Sumiten (registered trademark) TM, manufactured by Sumitomo Bayer Urethane Co., Ltd.) and 7.9 g of 2,4,6-tris (dimethylaminomethyl) phenol as a curing catalyst to a polyol mixing tank at room temperature. The mixture was stirred for 30 minutes to obtain 425.6 g of a mixture (hereinafter referred to as the mixture B).
10 kg of the coated product was charged in a rolling type coating apparatus capable of controlling the temperature. The rotating part of the coating device was rotated at 20 to 30 rpm, and the charged coated product was brought into a rolling state. While maintaining the temperature of the coated product to 70 to 75 ° C., 374.4 g of polymeric MDI (Sumidur (registered trademark) 44V10, manufactured by Sumitomo Bayer Urethane Co., Ltd.) and 425.6 g of mixture B were mixed as the polyisocyanate compound. The liquid uncured urethane resin composition obtained in this manner was gradually added and coated while being thermally cured. The time required for this coating treatment was about 56 minutes.
With respect to the resin-coated granular fertilizer having a urethane resin coating amount of 8% obtained in this manner, the fertilizer component elution performance was measured. The results are shown in Table 1.

Comparative Example 1
The same granular sulfuric acid as that used in Example 1 (water absorption at room temperature: 0.082 g-water / g-fertilizer, average particle size 3.5 mm) was used as it was in the same manner as in Example 1 to obtain a urethane resin. A resin-coated granular fertilizer having a coating amount of 4% was produced.
For this resin-coated granular fertilizer, the fertilizer component elution performance was measured. The results are shown in Table 1.

Comparative Example 2
The same granular sulfuric acid as used in Example 1 (water absorption at room temperature: 0.082 g-water / g-fertilizer, average particle size 3.5 mm) was used as it was in Example 2 to obtain a urethane resin. A resin-coated granular fertilizer having a coating amount of 8% was produced.
For this resin-coated granular fertilizer, the fertilizer component elution performance was measured. The results are shown in Table 1.

Example 3
(1) Manufacture of a coated processed product of granular fertilizer having a water absorption at room temperature of less than 0.01 g-water / g-fertilizer:
At room temperature, 20 kg of granular potassium chloride (water absorption at room temperature: 0.107 g-water / g-fertilizer, average particle size: 3.2 mm) was charged in a rolling type coating apparatus. The rotating part of the coating apparatus was rotated at 20 to 30 rpm, and the charged granular chloride was put into a rolling state. From the upper part of this animal, 200 g of mineral powder chlorophyll [149 μm (100 mesh) pass product, the same applies hereinafter] was gradually added and coated. Next, 200 g of a branched polyol polyether of a polyol compound (Sumiphen (registered trademark) TM, manufactured by Sumitomo Bayer Urethane Co., Ltd.) was spray-applied from the upper part of the animals and coated. The water absorption of the obtained coated product was 0.073 g-water / g-fertilizer. Since the water absorption is not less than 0.01 g-water / g-fertilizer, the coated product is further rolled under the same apparatus and the same conditions as above, 200 g of stone was gradually added to perform the coating treatment. Next, 200 g of the branched polyether polyol was spray-applied from the upper part of the animal and coated. The amount of water absorption of the coated product thus obtained was 0.039 g-water / g-fertilizer. Since the water absorption amount is not yet less than 0.01 g-water / g-fertilizer even after the two coating treatments, this coated animal is further rolled with the same equipment and the same conditions as above. From above, 200 g of the above-mentioned mesophyll was gradually added and coated. Next, 200 g of the branched polyether polyol was spray-applied from the upper part of the animal and coated. The amount of water absorption of the obtained coated processed product was 0.006 g-water / g-fertilizer.

(2) Production of resin-coated granular fertilizer:
The surface of the coated product of water absorption 0.006 g-water / g-fertilizer obtained in (1) was coated with a urethane resin by the following method to produce a resin-coated granular fertilizer. The coating amount of the urethane resin with respect to the coated product was 6%.
Add 313.3 g of branched polyether polyol (Sumiphen (registered trademark) TM, manufactured by Sumitomo Bayer Urethane Co., Ltd.) and 5.9 g of 2,4,6-tris (dimethylaminomethyl) phenol as a curing catalyst to a polyol mixing tank at room temperature. The mixture was stirred for 30 minutes to obtain 319.2 g of a mixture (hereinafter referred to as the mixture C).
10 kg of the coated product was charged in a rolling type coating apparatus capable of controlling the temperature. The rotating part of the coating device was rotated at 20 to 30 rpm, and the charged coated product was brought into a rolling state. While maintaining the temperature of the coated product to 70 to 75 ° C., 280.8 g of polymeric MDI (Sumijoule (registered trademark) 44V10, manufactured by Sumitomo Bayer Urethane Co., Ltd.) as a polyisocyanate compound and 319.2 g of mixture C were mixed. The liquid uncured urethane resin composition obtained in this manner was gradually added and coated while being thermally cured. The time required for this coating treatment was about 42 minutes.
With respect to the resin-coated granular fertilizer having a urethane resin coating amount of 6% obtained in this manner, the fertilizer component elution performance was measured. The results are shown in Table 1.

Example 4
Production of resin-coated granular fertilizer:
The surface of the coated product of water absorption 0.006 g-water / g-fertilizer obtained in Example 3 was coated with a urethane resin by the following method to produce a resin-coated granular fertilizer. The coating amount of the urethane resin with respect to the coated product was 10%.
At room temperature, 522.1 g of branched polyether polyol (Sumiten (registered trademark) TM, manufactured by Sumitomo Bayer Urethane Co., Ltd.) and 9.9 g of 2,4,6-tris (dimethylaminomethyl) phenol were added as a curing catalyst to a polyol mixing tank. The mixture was stirred for 30 minutes to obtain 532 g of a mixture (hereinafter referred to as the mixture D).
10 kg of the coated product was charged in a rolling type coating apparatus capable of controlling the temperature. The rotating part of the coating device was rotated at 20 to 30 rpm, and the charged coated product was brought into a rolling state. Obtained by mixing 468 g of polymeric MDI (Sumijoule (registered trademark) 44V10, manufactured by Sumitomo Bayer Urethane Co., Ltd.) as a polyisocyanate compound and 532 g of a mixture D while maintaining the temperature of the coated product to 70 to 75 ° C. The liquid uncured urethane resin composition was gradually added and coated while being thermally cured. The time required for this coating treatment was about 70 minutes.
With respect to the resin-coated granular fertilizer having a urethane resin coating amount of 10%, the fertilizer component elution performance was measured. The results are shown in Table 1.

Comparative Example 3
Using the same granular potassium chloride as used in Example 3 (water absorption at room temperature: 0.107 g-water / g-fertilizer, average particle size of 3.2 mm) as it is, urethane resin in the same manner as in Example 3. A resin-coated granular fertilizer with a coating amount of 6% was produced.
For this resin-coated granular fertilizer, the fertilizer component elution performance was measured. The results are shown in Table 1.

Comparative Example 4
Using the same granular potassium chloride as used in Example 3 (water absorption at room temperature: 0.107 g-water / g-fertilizer, average particle size 3.2 mm) as it is, urethane resin as in Example 4 A resin-coated granular fertilizer having a coating amount of 10% was produced.
For this resin-coated granular fertilizer, the fertilizer component elution performance was measured. The results are shown in Table 1.

As shown in Table 1, in the resin-coated granular fertilizer obtained by the method of the present invention, the initial elution of the fertilizer component is suppressed and the elution of the fertilizer component is controlled.

Claims (3)

  By coating 1 to 5 layers of mineral powder and a liquid polyol compound alternately at room temperature on a granular fertilizer surface having a water absorption of 0.01 g-water / g-fertilizer or more at room temperature, A resin-coated granular fertilizer characterized in that the amount of water absorption below is 0.001 g-water / g-fertilizer or more and less than 0.01 g-water / g-fertilizer and then the surface is coated with a resin coating material. Production method.   The method for producing a resin-coated granular fertilizer according to claim 1, wherein the coating amount of each layer of the mineral product powder and the polyol compound that is liquid at room temperature is 0.1 to 2 wt% with respect to the granular fertilizer. The method for producing a resin-coated granular fertilizer according to claim 1, wherein the resin coating material is a thermosetting resin.