JP3224070B2 - Plastic composition, resin molded product and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic composition as a molding material, and more particularly to a plastic composition containing paint waste.

[0002]

2. Description of the Related Art At the time of spray coating, not all of the paint mist sprayed from a coating gun adheres to an object to be coated, and a considerable amount of the mist scatters around. The paint mist scattered around is collected in circulating water in a washing booth and separated from the water in a treatment tank to become paint waste. This paint waste is a mixture in which various substances such as resin, pigment, solvent and water are mixed at various ratios, and it is difficult to reuse the paint anymore. .

[0003] However, even when incinerated, unburned harmful gas and unpleasant odor may be generated. There is also a problem that the furnace is corroded by acid gas generated during combustion. Furthermore, the amount of paint waste generated in daily painting operations is enormous, which is a waste of resources. Therefore, the reuse of paint waste was studied, for example, in Japanese Patent Application Laid-Open No. 55-18450,
Grind paint waste to about 150 μm or less,
A plastic composition which is heat-treated at ~ 300 ° C and mixed into a polyolefin resin is disclosed.

[0004] JP-A-6-9793 discloses a molding method using the plastic composition.

[0005]

By the way, paint waste generated in the painting process of automobiles contains a melamine resin which is generally used as a cross-linking agent in intermediate coatings and top coatings. Since this melamine resin is synthesized using melamine and formaldehyde as main raw materials, formaldehyde is generated by a self-condensation reaction or the like.

[0006] Therefore, when a plastic composition mixed with paint waste powder generated in a painting process of an automobile is formed into a pellet or a product shape, formaldehyde gas is generated and released from the melamine resin by heat during the molding. Is done. This formaldehyde gas has a strong odor and is a harmful substance that causes symptoms such as tears in the eyes, and is a major cause of deterioration of the working environment. Also, formaldehyde remained in the molded article, which sometimes caused an unpleasant odor of the molded article.

[0007] Therefore, it has been suggested that activated carbon or sepiolite is mixed into a plastic composition to adsorb the formaldehyde generated. However, these substances have almost no effect of adsorbing formaldehyde and preventing the release of gas. In addition, it has been clarified that the addition of these substances lowers the physical properties of the molded article. The present invention has been made in view of such circumstances, and it is an object of the present invention to prevent the emission of formaldehyde gas during molding and improve the working environment without deteriorating the physical properties of molded articles.

[0008]

According to the present invention, there is provided a plastic composition comprising a polyolefin resin, a paint waste powder containing an amino resin, and a paint waste powder.
It is characterized by mixing 1 to 5 parts by weight of urea powder with respect to parts by weight . Also, the method of manufacturing the resin molded product of the present invention
The feature of the method is that the coating contains polyolefin resin and amino resin.
Powder waste powder and urea powder,
From formaldehyde generated from urea powder
Prepare a plastic composition containing roll urea, plus
Methylol urea when heating and molding the tic composition
Reinforcement material made of thermosetting polymethylene urea by reaction
Is to generate. The characteristics of the resin molded product of the present invention
Signs are paint waste containing polyolefin resin and amino resin
Powder and urea powder are mixed to generate from paint waste powder
Formaldehyde reacting with urea powder
Preparing a plastic composition containing urea, plastic
Methylol urea reacts when the composition is heated and molded.
To produce a reinforcing material composed of thermosetting polymethylene urea
Manufactured in a polyolefin resin.
At least include polymethylene urea as a reinforcing material.
You.

[0009]

The plastic composition of the present invention contains urea powder. This urea powder easily reacts with formaldehyde as shown in Formula 1 to produce methylol urea. Therefore, formaldehyde generated from the amino resin is trapped by the urea, and the release to the outside is prevented.

[0010]

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The produced methylol urea reacts with the heat of molding as shown in the following formula [2] to form a thermosetting polymethylene urea represented by the following formula [3]. Because the polymethylene urea functions as a reinforcing material, the mechanical properties such as the strength of the molded product are improved.

[0012]

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[0013]

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[0014]

【Example】

[Specific examples of the present invention] As the polyolefin resin, polypropylene, polyethylene, ethylene propylene copolymer and the like can be used. Examples of the amino resin contained in the paint waste include a melamine resin, a urea resin, a benzoguanamine resin, and a co-condensation resin thereof.

The mixing ratio between the paint waste and the polyolefin resin is preferably as large as possible from the viewpoint of performance, but if the paint waste does not exceed 50% by weight, it has sufficient physical properties as a molded article. ing. In particular, when the content is 30% by weight or less, it is clear that the flexural strength is improved as compared with a pure polyolefin molded body in which no paint waste is mixed.

The amount of urea to be added is desirably determined according to the concentration of amino resin in the paint waste. However, in the case of general melamine crosslinkable paint waste (containing 10 to 30% by weight of amino resin), the amount of urea is preferably determined. If so, a range of 1 to 5 parts by weight is appropriate for 100 parts by weight of paint waste. If the amount of urea is too small, formaldehyde cannot be completely caught, and if the amount is too large, the generation of ammonia becomes remarkable, the working environment is deteriorated, and the physical properties of the molded product are sometimes reduced.

As a method of molding a molded article using the plastic composition of the present invention, the uncured resin in the paint waste reacts when heated for a long time, so that it is present as a foreign substance in the molded article. A molding method such as extrusion molding that keeps a molding material in a heated and molten state for a long time cannot be used, and hot press molding is mainly used. In some cases, injection molding can be used. [Embodiment] Hereinafter, the present invention will be described specifically with reference to embodiments. (Example 1) (1) Preparation of paint waste powder 6 kg of paint waste accumulated in the coating circulating water pit of the car body middle coat / top coat paint line can be sealed and equipped with a crushing wing and a 20-liter capacity processing tank. And pulverize with a rotary blade while heating with steam, strain with a wire mesh,
It was a paint waste powder of μm or less. The properties of the paint waste powder are as shown in Table 1.

[0018]

[Table 1] (2) Mixing Step The above-mentioned paint waste powder, polypropylene powder having a particle size of 500 μm or less (manufactured by Mitsui Toatsu Co., Ltd.) and urea powder (manufactured by Sumitomo Chemical Co., Ltd.) are charged into a treatment tank having a rotor,
Mix until uniform. The mixing ratio was such that the paint waste powder and the polypropylene powder were in a weight ratio of 1: 1, and the mixture was mixed with urea in an amount of 0, 1, 2, 3, 5% by weight. Was obtained. (3) Molding process Each of these plastic compositions was weighed in an amount of 70 g and charged into a mold.
Hot press molding was performed using a 26-ton press under the conditions of 00 kg / cm ³ and a press time of 1 minute to form flat test pieces of 220 × 220 × 3 mm. The gas generated during molding was sampled 350 mm above the upper surface of the mold, and the amounts of formaldehyde and ammonia contained were measured using a Kitagawa detector tube. The results are shown in FIG. (4) Evaluation From FIG. 1, it can be seen that the formaldehyde concentration sharply decreases by adding urea, and the formaldehyde concentration decreases as the amount of urea added increases. However, as the amount of addition increases, the concentration of ammonia generated by the decomposition of urea increases. Therefore, considering the balance between the two, it is understood that the amount of urea added is preferably about 2% by weight. (Example 2 / Comparative Example) (1) Preparation of paint waste powder 6 kg of paint waste accumulated in the paint circulating water pit of the car body middle coat / top coat paint line can be sealed with a crushing wing in a volume of 20 liters. Into a processing tank, pulverized by a rotary blade while heating with steam, strained with a wire mesh,
It was a paint waste powder of μm or less. The properties of the paint waste powder are as shown in Table 2.

[0019]

[Table 2] (2) Mixing process As shown in Table 3, 9.5 g of the above-mentioned paint waste powder and a particle size of 5 wt.
Polypropylene powder of 00 μm or less (Mitsui Toatsu Co., Ltd.
142.1g) and polyethylene pellets (Kojima Sangyo Co., Ltd.)
38 g) and 0.4 g of urea powder (manufactured by Sumitomo Chemical Co., Ltd.) were charged into a processing tank having a rotating blade, and mixed until uniform to obtain a plastic composition of this example. Also, without using urea powder, plastic compositions of Comparative Examples were similarly prepared with the compositions shown in Table 3.

[0020]

[Table 3] (3) Molding Step These plastic composition powders were fed to a 155 rpm 40φ extruder, and extruded and cut at 220 ° C. to form pellets each having a diameter of 2 to 3 mm and a length of 3 to 4 mm by 170 kg each. (4) Evaluation In the above-mentioned molding step, the odor of the working environment around 1 m of the extruder and the odor of the obtained pellets were sensory-evaluated for the plastic compositions of Example 2 and Comparative Example. As a result, in the case of the comparative example, a strong smell of formaldehyde was felt, whereas in the case of the example 2, almost no smell of formaldehyde was recognized, and there was a remarkable difference.

With respect to each of the obtained pellets, Izod impact value, heat deformation temperature, tensile strength, tensile elongation, bending strength, flexural modulus, MI value, hardness and density were measured by a conventional method. Table 4 shows the results.

[0022]

[Table 4] From Table 4, it can be seen that Example 2 shows physical properties that are superior to those of Comparative Example as a whole, which is attributable to the fact that Example 2 contains a product resulting from the reaction between formaldehyde and urea. it is obvious.

[0023]

According to the plastic composition of the present invention, even when a paint waste powder containing an amino resin is used,
The release of formaldehyde gas during molding and from molded products can be prevented, and the working environment is improved. In addition, the mechanical properties of the molded product are improved.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of urea added and the concentrations of released formaldehyde and ammonia in Examples.

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Claims (3)

(57) [Claims] 1. A paint waste powder containing a polyolefin resin and an amino resin, and 100 parts by weight of the paint waste powder .
And 1 to 5 parts by weight of urea powder. 2. It contains a polyolefin resin and an amino resin.
The paint waste powder and the urea powder are mixed, and the paint waste powder is mixed.
Formaldehyde generated from the powder reacts with the urea powder
Preparing a plastic composition containing methylol urea,
When the plastic composition is molded by heating,
Urea to react with thermosetting polymethylene urea
Of resin molded products characterized by producing a reinforcing material
Construction method. 3. A device manufactured by the manufacturing method according to claim 2.
At least polymethylene urea is supplemented in the polyolefin resin.
A resin molded product characterized as containing as a strong material.