# US 4,400,374 A · Controlled release of compounds utilizing a plastic matrix

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- Number: US 4,400,374 A
- Document ID: US4400374A
- Status: Granted
- Kind: A
- Application number: 06/171,835
- Filed: 1980-07-24
- Granted: 1983-08-23
- Earliest claimed: 1978-06-19
- Assignees: Environmental Chemicals, Inc.
- Inventors: Nathan F. Cardarelli
- Web page: https://patentgrep.com/patent/US4400374A

## CPC

- C08J 9/26: by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out
- A01M 1/2055: {Holders or dispensers for solid, gelified or impregnated insecticide, e.g. volatile blocks or impregnated pads}
- A01N 25/10: Macromolecular compounds
- A01N 25/34: Shaped forms, e.g. sheets, not provided for in any other sub-group of this main group
- C05D 9/02: containing trace elements
- C05G 5/40: Fertilisers incorporated into a matrix
- C08J 2201/0444: Salts
- C08J 2323/02: not modified by chemical after treatment
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- A01M: CATCHING, TRAPPING OR SCARING OF ANIMALS (appliances for catching swarms or drone-catching A01K57/00; fishing A01K69/00 - {A01K99/00}; biocides, pest repellants or attractants A01N); APPARATUS FOR THE DESTRUCTION OF NOXIOUS ANIMALS OR NOXIOUS PLANTS
- A01N: PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF (preservation of food or foodstuff A23); BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES (preparations for medical, dental or toiletry purposes which kill or prevent the growth or proliferation of unwanted organisms A61K); PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- C05D: INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
- C05G: MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS (organic fertilisers containing added bacterial cultures, mycelia, or the like C05F11/08; organic fertilisers containing plant vitamins or hormones C05F11/10); FERTILISERS CHARACTERISED BY THEIR FORM

## Abstract

A composition and method for the controlled release of compounds from a plastic dispenser, usually a thermoplastic, generally in association with a porosigen in contact with water, for example, an aquatic environment or soil moisture. Thermoplastic dispensers are generally made from a water insoluble polymer such as polyethylene, polypropylene, ethylene vinyl acetate, polyamide, polystyrene, polyvinyl acetate, polyurethane, etc. Thermoset plastics, such as epoxy, are also used. The porosigen, depending upon the desired end use and release rate of a compound, can have a solubility of less than 0.1 or 0.001 grams per 100 grams of water, or up to 100 grams per 100 grams of water. The released compound, for example, a larvicide, a molluscicide, a nematicide, a trace nutrient, a plant regulant, etc., is contained in the thermoplastic dispenser. The combination of the plastic dispenser containing the porosigen and compound results in a slow release which can last for days, months, and even years, through dissolution of the porosigen and the formation of a porous network permitting water to contact the dispersed compound located in the interior portions of the dispenser.

## Claims

### Claim 1

A floating controlled release pesticide dispenser, comprising:
a polymer, an aquatic pesticide, and a porosity inducing agent,
said polymer in the form of a matrix and containing said aquatic pesticide and said porosity inducing agent,
the amount of said polymer being 100 parts by weight,
said polymer of said matrix selected from the group consisting of a thermoplastic polymer, a thermoset polymer, and combinations thereof;
said aquatic pesticide being a pesticide for destroying aquatic pests in an aqueous environment, the amount of said pesticide ranging from about 2 parts by weight to about 80 parts by weight per 100 parts of said polymer except when said pesticide is an organotin compound, the amount of said organotin compound ranging from about 25 to about 75 parts; and
said aquatic pesticide slowly being released from the dispenser;
said dispenser having a density of less than 1.0 grams per cc; and
an anchor, said anchor having a density of greater than 1.0 grams per cc and connected to said dispenser.

### Claim 2 (depends on 1)

A floating controlled release pesticide dispenser according to claim 1, wherein said thermoplastic polymers are selected from the group consisting of polyolefins made from monomers having from 2 to 10 carbon atoms, polystyrene, substituted polystyrene, the acrylic polymers, the polyvinyl ethers, the polyvinyl acetals, the halogen-containing polymers, the nylons, the polyethers, polyesters, polyurethanes, the cellulose plastics, and combinations thereof, and wherein said thermoset polymers are selected from the group consisting of phenolics, the epoxides, the amino resins, the unsaturated polyesters, the urethane foams, the silicone polymers, and combinations thereof.

### Claim 3 (depends on 2)

A floating controlled release pesticide dispenser according to claim 2, wherein the porosity of said porosity agent is 0.1 grams or less per 100 grams of water, wherein the amount of said porosity agent ranges from about 5 to about 70 parts per 100 parts of polymer except for said organotin compound in which the amount of porosity agent ranges from about 15 to about 70 parts.

### Claim 4 (depends on 3)

A floating controlled release pesticide dispenser according to claim 3, wherein said pesticide is selected from the group consisting of tetramethyl-O,O'-thiodi-p-phenylene phosphorothioate; O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate; O,O-dimethyl phosphorodithioate ester of diethyl mercaptosuccinate, a compound having the formula R.sub.3 S.sub.n X where R.sub.3 is selected from the group consisting of an alkyl group having from 1 to 8 carbon atoms, an aryl group, and a substituted aryl group wherein said substituted group is an alkyl or an ester containing from 1 to 6 carbon atoms; X is selected from the group consisting of a halogen, an oxide, an alkoxy OR.sup.1 where R.sup.1 is an alkyl having from 1 to 12 carbon atoms, or an ##STR2## group where R" is an alkyl having from 1 to 12 carbon atoms; 2-(1-methylethoxy)phenyl methylcarbamate; dimethyl-1,2-dibromo-2,2-dichloroethyl phosphate; 6,7,8,9,10,10a-hexachloro-1,5,5a,6,9,9a-hexahydro-6,-methano-2,4,3-benzodi oxathiepen-3-oxide; 1-naphthyl methylcarbamate; gamma-1,2,3,4,5,6-hexachlorocyclohexane; 2-(1-methylethoxy)phenol methylcarbamate; 1,2,12,12a-tetrahydro-2-isopropenyl-8,9-dimethyl-(1)-benzopyrano-(3,4,6)-f uro-(2,3,6)(1)-benzopyran-6(6a)H-one; dichlorodiphenyltrichloroethane; 2,2-bis(p-methoxyphenyl)-1,1,1-trichloroethane; N-[(4-chlorophenyl)(amino)(carbonyl)]-2,6-difluorobenzamide; dimethyl 2,2-dichlorovinyl phosphate; O,O-dimethyl-O-(3-methyl-4-nitrophenyl) phosphorothioate; O,O-dimethyl-O-[3-methyl-4-(methylthio)phenyl] phosphorothioate; O,O-diethyl-O-O(3,5,6-trichloro-2-pyridyl)phosphorothioate; O,O-dimethyl-S-(N-methylcarbomoyl methyl)phosphorothioate; and O,O-dimethyl phosphorodithioate, S-ester with 4-(mercaptomethyl)-2-methoxy-1,3,4-thiodazoline 5-one.

### Claim 5 (depends on 4)

A floating controlled release pesticide dispenser according to claim 4, wherein said porosity agent is selected from the group consisting of an oxide and a salt, said oxide and said having a cation selected from the group consisting of the alkaline metals, the alkaline earth metals, iron, zinc, nickel, silver, and tin, and said salt having an anion selected from the group consisting of a carbonate, bicarbonate, nitrate, nitrite, nitride, peroxide, phosphate, phosphite, phosphide, sulfate, sulfite, and sulfide, which have a solubility of less than 0.1 grams per 100 grams of water.

### Claim 6 (depends on 5)

A floating controlled release pesticide dispenser according to claim 5, wherein said thermoplastic polymer has a number average molecular weight of from about 10,000 to about 1,000,000 and wherein said thermoset polymer is crosslinked, said polymer selected from the group consisting of polyethylene including low density polyethylene or high density polyethylene, polypropylene, a copolymer of ethylene and propylene, a copolymer of ethylene-vinyl acetate, polybutylene, polystyrene, poly-alpha-methylstyrene, polymethylacrylate, polyacrylate, polymethylmethacrylate, polyvinyl acetate, polyvinyl butyral, polyvinyl chloride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polyamide, polyoxymethylene, polyethyleneterephthalate, cellophane, rayon, a copolymer of ethylene-propylene, and combinations thereof.

### Claim 7 (depends on 6)

A floating controlled release pesticide dispenser according to claim 6, wherein the amount of said pesticide ranges from about 3 to about 50 parts, wherein the amount of said organotin compound ranges from about 40 to about 70 parts, wherein the amount of said porosity agent ranges from about 15 to about 35 parts, and wherein the amount of said porosity agent for said organotin compound ranges from about 25 to about 60 parts, and wherein said organotin compound is tributyltin oxide or tributyltin fluoride.

### Claim 8 (depends on 7)

A floating controlled release pesticide dispenser according to claim 7, wherein said thermoplastic polymer is selected from the group consisting of polyethylene, a copolymer of ethylene-vinylacetate, polypropylene, polystyrene, polyester, and combinations thereof; and
wherein said thermoset polymer is selected from the group consisting of epoxy, phenolic, and combinations thereof, and wherein said porosity agent has a porosity of 0.01 grams or less per 100 grams of water.

### Claim 9 (depends on 8)

A floating controlled release pesticide dispenser according to claim 8, wherein said porosity-inducing agent is selected from the group consisting of magnesium carbonate, calcium carbonate, and strontium carbonate.

### Claim 10 (depends on 9)

A floating controlled release pesticide dispenser according to claim 9, wherein said pesticide is selected from the group consisting of tributyltin fluoride, tributyltin oxide, O,O,O',O'-tetramethyl-O,O-thiodi-p-phenylene phosphorothioate; O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)phosphorothioate; O,O-dimethyl phosphorodithioate ester of diethyl mercaptosuccinate; dimethyl-1,2-dibromo-2,2-dichloroethyl phosphate; O,O-dimethyl-O-(3-methyl-4-nitrophenyl)phosphorothioate; and combinations thereof.

### Claim 11 (depends on 2)

A floating controlled release pesticide dispenser according to claim 2, wherein said porosity agent has a solubility of from about 0.1 to about 100 grams per 100 grams of water, and wherein the amount of said porosity agent ranges from about 1 to about 60 parts by weight per 100 parts of said polymer.

### Claim 12 (depends on 11)

A floating controlled release pesticide dispenser according to claim 11, wherein said pesticide is selected from the group consisting of tetramethyl-O,O'-thiodi-p-phenylene phosphorothioate; O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)phosphorothioate; O,O-dimethyl phosphorodithioate ester of diethyl mercaptosuccinate, a compound having the formula R.sub.3 S.sub.n X where R.sub.3 is selected from the group consisting of an alkyl group having from 1 to 8 carbon atoms, an aryl group, and a substituted aryl group wherein said substituted group is an alkyl or an ester containing from 1 to 6 carbon atoms; X is selected from the group consisting of a halogen, an oxide, an alkoxy OR.sup.1 where R.sup.1 is an alkyl having from 1 to 12 carbon atoms, or an ##STR3## group wherein R" is an alkyl having from 1 to 12 carbon atoms; dimethyl-1,2-dibromo-2,2-dichloroethyl phosphate; 6,7,8,9,10,10a-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzod ioxathiepen-3-oxide; 1-naphthyl methylcarbamate; gamma-1,2,3,4,5,6-hexachlorocyclohexane; 2-(1-methylethoxy)phenol methylcarbamate; 1,2,12,12a-tetrahydro-2-isopropenyl-8,9-dimethoxy-(1)-benzopyrano-(3,4,6)- furo-(2,3,6)(1)-benzopyran-6(6a)H-one; dichlorodiphenyltrichloroethane; 2,2-bis(p-methoxyphenyl)-1,1,1-trichloroethane; N-[(4-chlorophenyl)(amino)(carbonyl)]-2,6-difluorobenzamide; dimethyl 2,2-dichlorovinyl phosphate; O,O-dimethyl,O-(3-methyl-4-nitrophenyl) phosphorothioate; O,O-dimethyl-O-[3-methyl-4-(methylthio)phenyl]phosphorothioate; O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)phosphorothioate; O,O-dimethyl-S-(N-methylcarbomoyl methyl)phosphorodithioate; and O,O-dimethyl phosphorodithioate, S-ester with 4-(mercaptomethyl)-2-methoxy-1,3,4-thiodiazoline 5-one.

### Claim 13 (depends on 12)

A floating controlled release pesticide dispenser according to claim 12, wherein said thermoplastic polymer has a number average molecular weight of from about 10,000 to about 1,000,000 and said thermoplastic polymer is crosslinked, said polymer selected from the group consisting of polyethylene including low density polyethylene or high density polyethylene, a copolymer of ethylene and propylene, a copolymer of ethylene-vinylacetate, polypropylene, polybutylene, polystyrene, poly-alpha-methylstyrene, polymethylacrylate, polyacrylate, polymethylmethacrylate, polyvinyl acetate, polyvinyl butyral, polyvinyl chloride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polyamide, polyoxymethylene, polyethyleneterephthalate, cellophane, rayon, and combinations thereof.

### Claim 14 (depends on 13)

A floating controlled release pesticide dispenser according to claim 13, wherein the amount of said pesticide ranges from about 3 to about 50 parts, wherein the amount of said organotin pesticide ranges from about 40 to about 70 parts, wherein the amount of said porosity agent ranges from about 2 to about 20 parts per 100 parts of polymer, wherein said porosity agent is selected from the group consisting of halogenated metals, the halogenated alkaline earth metals, halogenated nickel, halogenated tin, halogenated silver, ammonium bromide, ammonium carbonate, ammonium chlorate, ammonium chloride, ammonium fluoride, ammonium sulfate, sodium carbonate, and sodium bicarbonate.

### Claim 15 (depends on 3, 4, 6)

A floating controlled release pesticide dispenser according to claim 3, 4, 6, or 8, wherein said porosity agent has a solubility of from about 0.1 to about 0.0005.

### Claim 16 (depends on 1, 3, 4, 6, 8, 9, 10, 11, 12, 13)

A floating controlled release pesticide dispenser according to claim 1, 3, 4, 6, 8, 9, 10, 11, 12 or 13, wherein said anchor causes said floating dispenser to reside within an aqueous environment.

### Claim 17 (depends on 16)

A floating controlled release pesticide dispenser according to claim 16, wherein said anchor weighs from about 2 to about 10 times the amount of said floating dispenser.

### Claim 18 (depends on 16)

A floating controlled release pesticide dispenser according to claim 16, wherein said floating dispenser is in the form of strands.

### Claim 19 (depends on 16)

A floating controlled release pesticide dispenser according to claim 16, wherein said floating dispenser is in the form of a bimodal pellet.

### Claim 20 (depends on 16)

A floating controlled release pesticide dispenser according to claim 16, wherein said floating dispenser is in the form of a chip.

### Claim 21

A controlled release pesticide dispenser, comprising:
a polymer, an aquatic pesticide, and a porosity inducing agent,
said polymer in the form of a matrix and containing said aquatic pesticide and said porosity inducing agent,
the amount of said polymer being 100 parts by weight, said polymer selected from the group consisting of a thermoplastic polymer, a thermoset polymer, and combinations thereof,
said aquatic pesticide being a pesticide for destorying animal aquatic pests in an aqueous environment, the amount of said pesticide ranging from about 2 parts to about 80 parts by weight per 100 parts of said polymer, except when said pesticide is an organotin compound, the amount of said organotin compound ranging from about 25 to about 75 parts, and
said aquatic pesticide slowly being released from the dispenser, and porosity agent having a solubility of 100 grams or less per 100 grams of water.

### Claim 22 (depends on 21)

A controlled release pesticide dispenser according to claim 21, wherein said pesticide is selected from the group consisting of tetramethyl-O,O'-thiodi-p-phenylene phosphorothioate; O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)phosphorothioate; O,O-dimethyl phosphorodithioate ester of diethyl mercaptosuccinate, a compound having the formula R.sub.3 S.sub.n X where R.sub.3 is selected from the group consisting of an alkyl group having from 1 to 8 carbon atoms, an aryl group, and a substituted aryl group wherein said substituted group is an alkyl or an ester containing from 1 to 6 carbon atoms; X is selected from the group consisting of a halogen, an oxide, an alkoxy OR.sup.1 where R.sup.1 is an alkyl having from 1 to 12 carbon atoms; 2-(1-methylethoxy)phenol methylcarbamate, dimethyl-1,2-dibromo-2,2-dichloroethyl phosphate; 6,7,8,9,10,10a-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzod ioxathiepen-3-oxide; 1-naphthyl methylcarbamate; gamma-1,2,3,4,5,6-hexachlorocyclohexane; 2-(1-methylethoxy) phenol methylcarbamate; 1,2,12,12a-tetrahydro-2-isopropenyl-8,9-dimethoxy-(1)-benzopyrano-(3,4,6)- furo-(2,3,6)(1)-benzopyran-6(6a)H-one; dichlorodiphenyltrichloroethane; 2,2-bis(p-methoxyphenyl)-1,1,1-trichloroethane; N-[ (4-chlorophenyl)(amino)(carbonyl]-2,6-difluorobenzamide; dimethyl 2,2-dichlorovinyl phosphate; O,O-dimethyl,O-(3-methyl-4-nitrophenyl) phosphorothioate; O,O-dimethyl-O-[3-methyl-4-methylthio)phenyl]phosphorothioate; O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)phosphorothioate; O,O-dimethyl-S-(N-methylcarbomoyl methyl)phosphorodithioate; and O,O-dimethyl phosphorodithioate, S-ester with 4-(mercaptomethyl)-2-methoxy-1,3,4-thiadiazoline 5-one.

### Claim 23 (depends on 22)

A controlled release pesticide dispenser according to claim 22, wherein said porosity agent has a solubility of less than 0.1 grams per 100 grams of water, wherein the amount of said porosity agent ranges from about 5 to about 70 parts except for said organotin compound in which the amount of porosity agent ranges from about 15 to about 70 parts by weight per 100 parts of polymer.

### Claim 24 (depends on 23)

A controlled release pesticide dispenser according to claim 23, wherein said thermoplastic polymers are selected from the group consisting of polyolefins made from monomers having from 2 to 10 carbon atoms, polystyrene, substituted polystyrene, the acrylic polymers, the polyvinyl ethers, the polyvinyl acetals, the halogen-containing polymers, the nylons, the polyethers, polyesters, polyurethanes, the cellulose plastics, and combinations thereof, and wherein said thermoset polymers are selected from the group consisting of phenolics, the epoxides, the amino resins, the unsaturated polyesters, the urethane foams, the silicone polymers, and combinations thereof.

### Claim 25 (depends on 24)

A controlled release pesticide dispenser according to claim 24, wherein said thermoplastic polymer has a number average molecular weight of from about 10,000 to about 1,000,000 and said thermoset polymer is crosslinked, said polymer selected from the group consisting of polyethylene, low density polyethylene, high density polyethylene, a copolymer of ethylene-vinylacetate, a copolymer of ethylene and propylene, polypropylene, polybutylene, polystyrene, poly-alpha-methylstyrene, polymethylacrylate, polyacrylate, polymethylmethacrylate, polyvinyl acetate, polyvinyl butyral, polyvinyl chloride, polytetrafluoroethylene, polychlorothrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polyamide, polyoxymethylene, polyethyleneterephthalate, cellophane, rayon, and combinations thereof.

### Claim 26 (depends on 25)

A controlled release pesticide dispenser according to claim 25, wherein the amount of said pesticide ranges from about 3 to about 50 parts, wherein the amount of said organotin compound ranges from about 40 to about 70 parts, wherein the amount of said porosity agent ranges from about 15 to about 35 parts, and wherein the amount of said porosity agent for said organotin compound ranges from about 25 to about 60 parts, and wherein said organotin compound is tributyltin oxide or tributyltin fluoride, and wherein said porosity agent has a solubility of less than 0.01 grams per 100 grams of water.

### Claim 27 (depends on 22)

A controlled release pesticide dispenser according to claim 22, wherein said porosity agent has a solubility of from about 0.1 to about 100 grams per 100 grams of water, and wherein the amount of said porosity agent ranges from about 1 to about 60 parts by weight per 100 parts of said polymer.

### Claim 28 (depends on 27)

A controlled release pesticide dispenser according to claim 27, wherein the amount of said pesticide ranges from about 3 to about 50 parts, wherein the amount of said organotin pesticide ranges from about 40 to about 70 parts, wherein the amount of said porosity agent ranges from about 2 to about 20 parts per 100 parts of said polymer, and wherein said polymer is selected from the group consisting of polyethylene including low density polyethylene or high density polyethylene, polypropylene, polybutene, polystyrene, poly-alpha-methylstyrene, polymethylmethalate, polymethylacrylate, polyacrylate, polymethylmethacrylate, polyvinyl acetate, polyvinyl butyral, polyvinyl chloride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polyamide, polyoxymethylene, polyethyleneterephthalate, cellophane, rayon, and combinations thereof.

### Claim 29 (depends on 28)

A controlled release pesticide dispenser according to claim 28, wherein said thermoplastic polymer has a number average molecular weight of from about 10,000 to about 1,000,000 and said thermoset polymer is crosslinked, said porosity agent is selected from the group consisting of halogenated metals, the halogenated alkaline earth metals, halogenated nickel, halogenated tin, halogenated silver, ammonium bromide, ammonium carbonate, ammonium chlorate, ammonium chloridem ammonium fluoride, ammonium sulfate, sodium carbonate, and sodium bicarbonate.

### Claim 30

A process for preparing a controlled release pesticide dispenser, comprising the steps of:
adding and mixing 100 parts by weight of a polymer, from about 2 to about 80 parts by weight per 100 parts of polymer of an aquatic pesticide except when said aquatic pesticide is an organotin compound, the amount of said organotin compound ranging from about 25 to about 75 parts, and a porosity inducing agent, said polymer selected from the group consisting of a thermoplastic polymer, a thermoset polymer, and combinations thereof;
forming a floating polymer matrix dispenser, said dispenser having a density of less than 1.0 grams per cc,
attaching said dispenser to an anchor, said anchor having a density of greater than 1.0 grams per cc.

### Claim 31 (depends on 30)

A process according to claim 30, wherein said polymer is selected from the group consisting of polyethylene, a copolymer of ethylene-vinylacetate, a copolymer of ethylene and propylene, polypropylene, polystyrene, a polyester and combinations thereof, or in said thermoset polymer which is selected from the group consisting of an epoxy, a phenolic, and combinations thereof, wherein said porosity agent is a compound having a solubility of less than 0.01 grams per 100 grams of water, the amount of said porosity agent ranging from about 5 to about 70 parts per 100 parts of polymer, except for said organotin compound in which said porosity agent ranges from about 15 to about 70 parts.

### Claim 32

A method for preparing a slow release pesticide dispenser, comprising the steps of:
adding and mixing 100 parts by weight of a polymer, an aquatic pesticide for use in an aqueous environment for destroying aquatic pests, and a porosity inducing agent having a solubility of 100 grams or less per 100 grams of water, the amount of said pesticide ranging from about 2 parts to about 80 parts by weight per 100 parts of said polymer, except wherein said pesticide is an organotin compound, the amount of said organotin compound ranging from about 25 parts to about 75 parts by weight per 100 parts of said polymer; and
forming a polymer matrix dispenser so that upon contact with an aqueous environment, said pesticide is slowly released therefrom.
said polymer selected from the class consisting of a thermoplastic and a thermoset.

### Claim 33

A method for the controlled release of pesticides from a floating dispenser into an aquatic environment, comprising:
(a) dispersing a floating matrix into the environment, said matrix comprising a polymer, an aquatic pesticide for destroying aquatic pests, and a porosity inducing agent,
said polymer selected from the group consisting of a thermoplastic polymer and a thermoset polymer;
(b) dissolving said porosity agent from said matrix at a controlled rate upon contact with water, to create a pore structure in said matrix;
(c) dislodging said aquatic pesticide through said pore structure from said matrix upon contact with water, said pesticide to retard or destroy undesired pests;
said porosity agent having a water solubility less than 100 grams per 100 grams of water and said polymer being water insoluble and non-porous;
said dispenser having a density of less than 1.0 grams per cc; and
an anchor, said anchor having a density of greater than 1.0 grams per cc and connected to said dispenser.

### Claim 34 (depends on 33)

A method for the controlled release of pesticides into an environment, according to claim 33, wherein said matrix further comprises a porosity agent modifying compound.

### Claim 35

A composition for destroying aquatic pests, comprising:
a mixture of an aquatic pesticidally effective active ingredient which is water dispersible and an inert particulate material having a water solubility from less than 100 grams per 100 grams of water at 25.degree. C.;
said mixture being dispersed within a water insoluble, non-porous polymer matrix, and being floatable;
said polymer selected from the group consisting of a thermoplastic and a thermoset,
the proportion of particulate material being sufficient to induce liquid porosity in said matrix upon exposure to water; and
an anchor, said anchor connected to said floatable mixture.

### Claim 36

A method for the controlled release of pesticides in an environment, comprising:
(a) dispersing a matrix into the environment, said matrix comprising an aquatic pesticide for destroying pests, and a porosity inducing agent, said polymer selected from the group consisting of a thermoplastic and a thermoset;
(b) dissolving said porosity agent from said matrix at a controlled rate upon contact with water, to create a pore structure in said matrix;
(c) dislodging said aquatic pesticide through said pore structure from said matrix upon contact with water, said pesticide to retard or destroy undesired pests; and
said porosity agent having a water solubility less than 100 grams per 100 grams of water and said polymer being water insoluble and non-porous.

### Claim 37 (depends on 36)

A method for the controlled release of pesticides into an environment, according to claim 36, wherein said matrix further comprises a porosity agent modifying compound.

### Claim 38

A composition for destroying aquatic pests, comprising:
a mixture of an aquatic pesticidally effective active ingredient which is water dispersible and an inert particulate material having a water solubility from less than 100 grams per 100 grams of water at 25.degree. C.;
said mixture being dispersed within a water insoluble, non-porous polymer matrix, said polymer selected from the group consisting of a thermoplastic, and a thermoset;
the proportion of particulate material being sufficient to induce liquid porosity in said matrix upon exposure to water.

### Claim 39 (depends on 1)

A floating controlled release pesticide dispenser according to claim 1, further comprising a second of said polymer selected from the group consisting of said thermoplastic and said thermoset, said second polymer having a melt index, said second polymer index having a disparity from said first polymer melt index of from about 5 to about 25 melt index units so that a free volume within said dispenser is created.

### Claim 40 (depends on 1)

A floating controlled release pesticide dispenser according to claim 1, wherein said porosity agent creates a pore structure in said matrix upon exposure to water.

### Claim 41 (depends on 1)

A floating controlled release pesticide dispenser according to claim 1, wherein said matrix further comprises a porosity agent modifying compound.

### Claim 42 (depends on 30)

A process according to claim 30, further comprising adding a second of said polymer selected from the group consisting of said thermoplastic and said thermoset, said second polymer having a melt index, said second polymer index having a disparity from said first polymer melt index of from about 5 to about 25 melt index units so that a free volume within said dispenser is created.

### Claim 43 (depends on 30)

A process according to claim 30, creating a pore structure with said porosity agent in said matrix upon exposure to water.

### Claim 44 (depends on 30)

A process according to claim 30, further comprising adding a porosity agent modifying compound.

### Claim 45 (depends on 21)

A controlled release pesticide dispenser according to claim 21, further comprising a second of said polymer selected from the group consisting of said thermoplastic and said thermoset, said second polymer having a melt index, said second polymer index having a disparity from said first polymer melt index of from about 5 to about 25 melt index units so that a free volume within said dispenser is created.

### Claim 46 (depends on 21)

A controlled release pesticide dispenser according to claim 21, wherein said porosity agent creates a pore structure in said matrix upon exposure to water.

### Claim 47 (depends on 21)

A controlled release pesticide dispenser according to claim 21, wherein said matrix further comprises a porosity agent modifying compound.

### Claim 48 (depends on 32)

A process according to claim 32, further comprising adding a second of said polymer selected from the group consisting of said thermoplastic and said thermoset, said second polymer having a melt index, said second polymer index having a disparity from said first polymer melt index of from about 5 to about 25 melt index units so that a free volume within said dispenser is created.

### Claim 49 (depends on 32)

A process according to claim 32, creating a pore structure with said porosity agent in said matrix upon exposure to water.

### Claim 50 (depends on 32)

A process according to claim 32, further comprising adding a porosity agent modifying compound.

### Claim 51 (depends on 26)

A controlled release pesticide dispenser according to claim 26, wherein said porosity agent is selected from the group consisting of magnesium carbonate, calcium carbonate, and strontium carbonate,
wherein said thermoplastic polymer is selected from the group consisting of polyethylene, a copolymer of ethylene-vinylacetate, polypropylene, polystyrene, polyester, and combinations thereof; and
wherein said thermoset polymer is selected from the group consisting of epoxy, phenolic, and combinations thereof.