JPH0513189B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a thermoplastic resin composition that has functions such as deodorization by containing ferrous sulfate with low water content in the form of fine powder, and The present invention relates to a thermoplastic resin molded product obtained by molding a composition, and a masterbatch for molding.

[Conventional technology]

Removal of bad odors generated in the living environment is one of the major themes related to the pursuit of comfort in life. Regarding the removal of bad odors, it is known that they are effective through various mechanisms such as masking action, adsorption action, and neutralization action, and deodorizers and deodorants that utilize these mechanisms have been commercialized. Reactive agents that utilize chemical reactions are superior in terms of their quick effects, but among so-called chemical deodorizers, ferrous sulfate has attracted particular attention in recent years because it has quick effects and is non-toxic. ing.

It is known that ferrous sulfate removes ammonia and that the reaction product of ferrous sulfate and ammonia has the ability to remove hydrogen sulfide (Japanese Patent Publication No. 30-6698, JP-A-51-50889). Publication No.). The mechanism is estimated to be the following reaction.

FeSO ₄ +2NH ₃ +2H ₂ O = (NH ₄ O) ₂ SO ₄ +Fe (OH) ₂ Fe (OH) ₂ + H ₂ S = FeS + 2H ₂ O [Object of the invention] By doing so, it is an object of the present invention to provide a thermoplastic resin composition for molding and a thermoplastic resin molded product having functions such as deodorization.

As a result of intensive research to achieve the above object, the present inventors have found that when ferrous sulfate is mixed with a thermoplastic resin under appropriate conditions and molded, the ferrous sulfate contained in the molded product, especially the molded product, is It has been discovered that the molded product exhibits a deodorizing function due to the action of ferrous sulfate present on the surface of the molded product, and also fulfills the original function of the molded product. This function is particularly effective in molded articles having a large specific surface area, and can effectively impart a deodorizing function to plastic bags for garbage disposal, for example.

Ferrous sulfate used in the present invention is a substance that has poor miscibility with resin, but as a method for uniformly dispersing and mixing a substance with poor miscibility into resin,
A method is used in which a masterbatch containing a high concentration of the target admixture is prepared, and the masterbatch is mixed with a molding resin at a predetermined ratio and molded.
It is also an object of the present invention to provide a masterbatch containing ferrous sulfate in a well-dispersed state and at a high concentration.

[Structure of the invention]

The present invention provides a deodorizing heat treatment product characterized by containing 0.5 to 90% by weight of fine powder of ferrous sulfate whose total water content of crystal water and free water is 20% by weight or less, preferably 15% by weight or less. The present invention relates to a plastic resin composition.

Ferrous sulfate can be obtained using normal manufacturing methods.
It is a water salt and is commercially available in this form. Sulfuric acid No. 1
When iron heptahydrate is mixed with a thermoplastic resin and heated to the melting temperature of the resin, for example 130° C., some of the water of crystallization is liberated and vaporized, thereby causing foaming. Therefore, a good molded product cannot be obtained in this state. Even if a resin with a low melting temperature is selected and molded in a short time, ferrous sulfate heptahydrate is easily oxidized by oxygen and moisture in the atmosphere and turns into ferric sulfate or ferric hydroxide. It is easy to cause discoloration, loss of efficacy, etc.

On the other hand, when heptahydrate is dried by heating at about 120°C, most of the crystallization water is lost and it becomes monohydrate. Ferrous sulfate monohydrate does not lose crystal water under normal thermoplastic resin molding conditions and does not foam during molding.
As mentioned above, ferrous sulfate heptahydrate is easily oxidized, is hygroscopic, and has extremely poor miscibility with hydrophobic resins, but monohydrate is less susceptible to oxidation and hygroscopicity.
It has high resistance to moisture absorption and good miscibility.

Since ferrous sulfate is hydrophilic, it usually adsorbs so-called free water in addition to crystallization water. It is recognized that heating ferrous sulfate at 300℃ for about 1 hour removes all moisture, so 300℃,
The weight loss rate in 1 hour treatment is defined as the total amount of crystal water and free water.

When the total water content of crystallization water and free water expressed in this way is 20% by weight or less, preferably 15% by weight or less, most of the ferrous sulfate exists as a monohydrate, and some of the ferrous sulfate exists as a monohydrate. It is considered to be mixed with water salt and can be advantageously used for the purpose of the present invention.

The ferrous sulfate used in the present invention needs to be a fine powder. The smaller the particle size of the fine powder, the fewer problems there will be during molding, and the larger the specific surface area, the greater the deodorizing ability. Particularly for garbage disposal bags, particles with a particle size of 30 μm or less are preferred. In order to obtain a fine powder with a small particle size, ferrous sulfate is preferably ground and sieved.

The thermoplastic resin raw material for molding used in the present invention is
It is not particularly limited as long as it can be injection molded or extruded. For example, polyolefin resins such as polyethylene, polypropylene, and polystyrene, vinyl resins such as polyvinyl chloride, polyvinylidene chloride, and polymethyl methacrylate, cellulose resins such as cellulose acetate, polyamide resins, polyester resins, polybutadiene,
Examples include diene elastomers such as polyisoprene, copolymer resins such as ethylene/vinyl acetate, and styrene/acrylonitrile. These are supplied to a molding machine in the form of pellets, powder, beads, granules, etc., and are molded by applying heat and pressure. When molding, it is difficult to disperse the resin raw material and ferrous sulfate fine powder sufficiently uniformly by directly mixing them, so the mixture is mixed in a blender and then transferred to a plastomill, kneader, roll, extruder, etc. The resin may be melted, kneaded, and crushed into a plate or rod shape to be used as a raw material to be supplied to a molding machine. The masterbatch pellets and resin pellets may be fed to a molding machine. When producing a masterbatch, in order to ensure good dispersion of ferrous sulfate in the resin composition, it is kneaded in advance with a low molecular weight resin with a molecular weight in the range of 1,500 to 60,000.
Masterbatch pellets can be prepared by coating the surfaces of ferrous sulfate particles with the low molecular weight resin, mixing it with a molding resin, and pelletizing it with a pellet molding extruder. At this time, resin with a molecular weight in the range of 1,500 to 60,000 is mixed with sulfuric acid.
The content is preferably 1/5 to 10 times the amount of fine iron powder.

The low molecular weight resin used for particle surface coating and the molding resin do not have to be the same type of resin as long as they have sufficient compatibility, and resins with slightly different compositions can also be used. The reason for using low molecular weight resins is that they have better fluidity than molding resins and can be sufficiently kneaded, but if the molecular weight is too small, the viscosity will be too low and the specific gravity will be higher than that of resins. Mixing with ferrous sulfate powder becomes even more difficult.

When molding resin, antioxidants, colorants,
It is also possible to add commonly used additives such as ultraviolet absorbers, antistatic agents, flame retardants, and lubricants, or other fillers.

〔Effect of the invention〕

As already mentioned, ferrous sulfate reacts with ammonia, and the reaction product of ferrous sulfate and ammonia reacts with hydrogen sulfide, and by incorporating ferrous sulfate into a thermoplastic resin, , can impart deodorizing ability. For example, a masterbatch with a ferrous sulfate content of 20% by weight is created, mixed with polyethylene resin, and then inflation extruded to form a garbage disposal bag, which generates almost no odor from the stored kitchen waste. When used in the kitchen, the environment can be improved.

Moreover, the masterbatch according to the present invention is
Since it contains a high concentration of iron, it can also be used as a solid deodorizer.

Conventional solid deodorizers are porous or gel-supported or encapsulated substances that have a deodorizing effect, and there are almost no solid deodorizers that are dense continuous bodies like thermoplastic resin moldings. In the present invention as well, it is thought that the particles that actually exhibit the deodorizing effect are limited to the particles exposed on the surface of the molded article and the particles near the surface that are covered with a thin resin layer. Among them, those exposed on the surface are eluted by washing with water, but the particles covered with a thin resin layer are not eluted by washing with water, but are thought to react with the malodorous gases diffused in the resin layer and deodorize them. In addition, the particles under such a thin resin layer have less immediate deodorizing ability than particles exposed on the surface, but they have a sustained effect and are highly resistant to oxidative deactivation due to oxygen in the air. It is expected.

The thermoplastic resin composition of the present invention containing ferrous sulfate particles has various functions in addition to the deodorizing function. One of the things that has been confirmed so far is the decomposition of free chlorine in water. That is, when water containing free chlorine for sterilization is placed in a thermoplastic resin molding containing ferrous sulfate particles, the free chlorine is rapidly decomposed and the water is turned into so-called "tasty water."

〔Example〕

The present invention will be explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 Commercially available ferrous sulfate heptahydrate was vacuum dried at 120° C. for 2 hours to obtain a powder with a total water content of crystal water and free water of 13.9%. This powder was further finely pulverized using an ACM-10 type balberizer (manufactured by Hosokawa Iron Works Co., Ltd.).
It was made into a fine powder with an average particle size of 8.6 μm and a maximum particle size of 30 μm.
Add 40 parts by weight of the above fine powder to an average molecular weight of approximately 5000 and a density of
19 parts by weight of low molecular weight polyethylene wax of 0.93 g/cm ³ and tetrakis[methylene-3-(3',5'-
1 part by weight of di-tertbutyl-4'-hydroxyphenylpropionate]methane was added and melt-kneaded at 120°C using three rolls to obtain a wax coated product. This wax coated product has a density of 0.923g/
cm ³ , melt flow index 7 g/10 minutes, 140 parts by weight of low-density polyethylene powder passed through 20 meshes was added, mixed in a tumbler type blender, and then heated to a molten resin temperature of 130°C under a reduced pressure of 350 Torr using a single screw extruder. Extruded with 20% ferrous sulfate
A polyethylene masterbatch pellet containing the following was prepared.

The deodorizing performance of the masterbatch pellet itself was measured by the following method.

Ammonia concentration 520ppm and hydrogen sulfide concentration
15 g of pellets were placed in a sealed container with a capacity of 9.7 and containing 35 ppm, and the gas concentration was measured after 4 hours using a detection tube. The above gas concentration approximately corresponds to the level of the atmosphere of the human waste vortex. As a result, the removal rates of ammonia and hydrogen sulfide by the masterbatch pellets were 96% and 88%, respectively.

Comparative Examples 1, 2 In place of the ferrous sulfate used in Example 1, a fine powder obtained by pulverizing commercially available ferrous sulfate heptahydrate (Comparative Example 1)
Masterbatch preparation was attempted in the same manner as in Example 1 using a sample (Comparative Example 2) obtained by drying the fine powder with ventilation at 60° C. for 24 hours. The total amount of crystal water and free water was 46.4% for the sample of Comparative Example 1, and 46.4% for the sample of Comparative Example 2.
The percentage of samples was 32.5%. However, it was not possible to obtain a coated product due to severe foaming during the wax kneading process.

Example 2 Masterbatch pellet 1 produced in Example 1
Add 9 parts by weight, 4 parts by weight, and 2.3 parts by weight of the same low-density polyethylene used in Example 1 to the parts by weight, respectively, and use an inflation film forming apparatus to form a film with a width of 200 mm at a melting temperature of 140°C and a cooling temperature of 80°C. , cylindrical films with a thickness of 40 μm were molded (ferrous sulfate content: 2%, 4%, and 6.7%).

2 g of the above film (approx. 200 mm x 300
mm) and measured the gas concentration 4 hours later. As a result, the ammonia removal rates by the films were 75%, 90%, and 94%, respectively.

Comparative Example 3 In place of ferrous sulfate in Example 1, the total moisture content of crystal water and free water was 10.6%, but the average particle size was 52 μm,
Masterbatch pellets having a ferrous sulfate content of 20% were prepared according to the method of Example 1 using ferrous sulfuric acid having a maximum particle size of 85 μm. Using this masterbatch pellet, a low density polyethylene film was produced in the same manner as in Example 2. Although the surface of the film was noticeably rough, a film without pinholes was obtained.
When the ammonia deodorizing ability (after 4 hours) was measured in the same manner as in Example 2, it was found to be 63% (ferrous sulfate content 2%), 66% (ferrous sulfate content 4%), and 68% (ferrous sulfate content 4%). 1 iron content: 6.7%), and a result inferior to that of Example 1 was obtained.

Example 3 and Comparative Example 4 62.5 parts by weight of ethylene-propylene copolymer pellets having an ethylene content of 3.3% by weight and a melt flow index of 17 g/10 minutes were added to 37.5 parts by weight of the wax coated product produced in Example 1 using a super mixer to 120 parts by weight. The mixture was mixed under heating at ℃. After cooling, use a single screw extruder to reduce the pressure to 170°C under a vacuum of 150Torr.
Masterbatch pellets containing 25% ferrous sulfate were prepared by extrusion at .degree. To 1 part by weight of this masterbatch pellet, 6 parts by weight of polypropylene pellets with a density of 0.90 g/cm ³ and a melt flow index of 5.5 g/10 minutes were added, and the pellets were molded using an inflation method film forming apparatus at a melting temperature of 180. A cylindrical film with a width of 260 mm and a thickness of 40 μm was formed at a cooling temperature of 25°C. A bag with a depth of 470 mm was made from this film (Example 3). Separately create bags of the same size that do not contain ferrous sulfate (Comparative Example 4), put 500g of kitchen waste into each bag, seal the mouth,
They were left outdoors in the autumn sunlight for 2 hours, opened, and compared for odor. As a result, the bag containing ferrous sulfate had almost no odor, but the bag not containing ferrous sulfate had a strong odor.

Example 4 To 1 part by weight of the polyethylene master batch pellets prepared in Example 1, 19 parts by weight of polyethylene pellets having a density of 0.920 g/cm ³ and a melt flow index of 1.9 g/10 minutes were added, and the melting temperature was 150. A polyethylene water bottle (main body) with a capacity of 650 c.c. and a weight of 85 g was manufactured by injection molding at ℃.

After thoroughly washing the water bottle, it was filled with tap water containing 0.7 ppm of free chlorine, and changes in free chlorine at room temperature were measured. As a result, after 30 minutes, the concentration was less than 0.1 ppm, and it was confirmed that the water was delicious and had no limescale odor.

Claims (1)

[Scope of Claims] 1. A deodorizing thermoplastic resin composition containing 0.5 to 90% by weight of fine powder of ferrous sulfate whose total moisture content of water of crystallization and free water is 20% by weight or less. . 2. The thermoplastic resin composition according to claim 1, wherein the fine powder of ferrous sulfate has a particle size of 30 μm or less. 3. The thermoplastic resin according to claim 1 or 2, which contains a thermoplastic resin having a molecular weight of 1,500 to 60,000 in an amount of 1/5 to 10 times the amount of ferrous sulfate fine powder. Composition.