JP3473914B2 - Method for miniaturizing coating film of resin molded product with coating film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the reuse of resin-molded waste products with a coating film.

[0002]

2. Description of the Related Art In recent years, it has become necessary to recycle waste resin moldings from the viewpoint of environmental protection. Resin molded products are also used for automobile parts, but many of the resin molded products are painted, and the reuse of the waste products has become an important issue. The coating film formed on these resin molded products is usually cross-linked and cured in a three-dimensional network, is thermosetting, does not melt, and does not dissolve in a solvent or the like. There is no method other than mechanical shaving to remove this coating film. Therefore, after mechanically removing the coating film by sandblasting in advance,
A method of crushing to obtain a recycled resin composition is conceivable. However, in this method, it takes a long time to remove a coating film on a part having a complicated three-dimensional surface, and it cannot be completely removed, which is industrially unsuitable.

As a method of recycling the resin molding waste products coated with the thermosetting paint, the crushed resin molding waste products are directly kneaded using a kneading device such as a multi-screw extruder to obtain a recycled resin composition for molding. How to do it is done. However, in this method, the coating film component does not melt in the kneading device and exists as a coarse foreign substance in the reclaimed resin composition for molding. Therefore, the mechanical properties of the resin molded product molded from the resin composition containing the pulverized product of the waste resin molded product are deteriorated. This deterioration in mechanical properties of the resin molded product is particularly remarkable in impact strength. For this reason, the recycled resin composition for molding is limited to a field where its use does not require impact strength.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and the resin molded article has a reduced impact strength in the kneading step without removing the coating film from the waste resin molded article with the coating film. The purpose is to make the coating film finer to the extent not shown.

[0005]

Means for Solving the Problems In the method for making a coating film resin product finely coated according to the present invention, a pulverized product of the coating resin product and a viscosity at 200 ° C. are η = 90 poise (g / cm ·
sec) Kneading and extruding a mixture with the thermoplastic base material resin as described above, and refining the coating film of the resin molded article with the coating film to such an extent that the moldability and physical properties of the thermoplastic base material resin are not affected. Is characterized by.

The resin-molded product with a coating film is usually a resin-molded product having a coating film of urethane paint and amino resin-based paint formed on its surface. For example, a molded product of olefin resin such as polypropylene resin or other general-purpose resin is used. is there. Specifically, there is a PP bumper waste product with a coating, which is a molded product of a kneaded product of a polypropylene resin and an amorphous polyolefin resin. The resin molded product with a coating film is put into an extruder or the like at the time of kneading and crushed to a size that allows extrusion molding.

The thermoplastic base material resin of the present invention is 20
A high-viscosity grade product of a normal resin having a high viscosity of 0 ° C. of η = 90 poise (g / cm · sec) or more, for example, polyethylene resin, polypropylene resin, nylon resin or the like can be used. This high-viscosity thermoplastic matrix resin imparts a large shearing force to the foreign material when the foreign material is added during kneading with an extruder or the like.
Therefore, when the pulverized product of the resin molded product with a coating film is mixed into the base material resin and kneaded, the coating film of the pulverized product is peeled off by the shearing force and heat of the base material resin, and the resin component is melted. The peeled coating film is further subjected to the shearing force of the base material resin to be made into fine particles.
As a result, the coating film of the resin molded article with a coating film becomes fine, and the moldability and physical properties of the resin composition containing the refined coating film,
In particular, it is possible to form a finely divided coating film to a size that does not affect the impact resistance.

The thermoplastic base material resin must have a high viscosity such that it can be kneaded in an extruder and has a large shearing force at the time of kneading. For example, the viscosity at 200 ° C. is η = 90 pois.
e or more can be used. If the viscosity of the thermoplastic base material resin is less than η = 90 poise, the shearing force applied to the coating film is insufficient and the coating film cannot be sufficiently miniaturized, which is not preferable. An extruder capable of sufficiently kneading the resin mixture can be used for the kneading. For example, single screw extruder, twin screw extruder,
A multi-screw extruder or the like can be used. The temperature at the time of kneading is preferably at least a molding temperature of the thermoplastic base material resin, and more preferably a temperature higher than the molding temperature of the resin having a high molding temperature in the resin mixture.

The amount of the pulverized product of the resin molded product with a coating added to the base material resin is preferably in the range of 5 to 30% by weight. If the amount added exceeds 30% by weight, the fineness of the coating film does not proceed uniformly, which is not preferable. Further, if the addition amount is less than 5% by weight, the utilization effect of the pulverized product is deteriorated, which is not preferable. Further, at the time of kneading the resin mixture, a compatibilizing agent that promotes compatibility between the base material resin and the resin of the resin molded article with a coating film can be added. Further, during kneading, the resin may be blended with an inorganic filler such as calcium carbonate, a pigment such as carbon black, an antioxidant, an ultraviolet absorber, a heat stabilizer, and a lubricant.

This kneaded product can be used as it is as a molding material, but it can also be used by mixing it in an appropriate amount with a new material of the same kind. This kneaded product can be applied with a usual resin molding method, but can also be used as a material for injection molding, stamping molding, and vacuum pressure molding.

[0011]

In the method of making a coating film fine according to the present invention, a mixture of a thermoplastic base material resin material having a high viscosity and a pulverized product of a resin molded article with a coating film is kneaded. Since the thermoplastic base material resin that serves as a matrix during kneading has a high viscosity, coexisting pulverized resin molding waste products with a coating film are subjected to shearing force and the coating film pieces are peeled from the resin, and further subjected to shearing force to reduce the size. Then, it becomes fine particles and is dispersed in the base material resin. The pulverized resin from which the coating film has been peeled is dispersed in the base material resin by heat and shearing force. Therefore, a molded product molded from a molding material containing this kneaded material does not have foreign matter of a large shape, so that the mechanical strength, for example, the impact strength at low temperature can be maintained at the same level as that of the new material. Therefore, the kneaded product treated by this method can be used as a normal molding material as it is or after being blended with a new material.

Therefore, the resin molding waste product with a coating film can be made into a recycled resin for molding by crushing and kneading without treating the coating film in advance.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples. (Example) Bumper waste made of polypropylene resin (P
P: 60% by weight, EPR 30% by weight, talc 10% by weight) was crushed into about 5 mm square. This pulverized product has a viscosity η = 9
0.2 poise (g / cm · sec at 200 ° C)
Was added to the high viscosity polyethylene (HEPE) at a ratio shown in Table 1 and kneaded at 220 ° C. for 5 minutes with a single-screw or twin-screw extruder. The amount of waste bumper added is no. 1 is 5%, No. 1 Two
Is 10%, No. 3 is 20%, No. 3 4 is 30%. No. No. 5 is No. The composition was the same as that of 2, and kneading was performed at 220 ° C. for 5 minutes with a uniaxial extruder.

30% by weight or more of PP bumper waste products are mixed.
When kneading, the amount of PP having a low melt tension is mixed in so much that the melt tension of high density polyethylene (HDPE) is lowered, so that stretchability during melting, vacuum pressure molding which requires high melt tension and the like become difficult. Also, the overall viscosity will decrease (the viscosity of PP is P
It is also difficult to make the coating film finer (1/30 of E). Further, the PP bumper was mixed more uniformly at 10% by weight, the heat resistance of the molded product was improved, and the vacuum pressure air moldability was the best. It is also possible to prepare a kneading masterbatch of the mixture in advance with an extruder and then dry blend it with HDPE pellets to adjust the blending amount. (Comparative Example) The PE viscosity of the base material resin was changed, and the content of the bumper waste product was adjusted to 10%, followed by kneading at 220 ° C. for 5 minutes with a twin-screw extruder. No. No. 1 has a viscosity η of 8.2 and No. 2 is viscosity η
14.2, No. No. 3 has a viscosity η of 15.9. N
o. No. 4 is No. The mixture of 3 was kneaded with a single screw extruder.

[0015]

[Table 1] (Effect of atomizing coating film) For biaxial kneading, the viscosity of the base material resin used and the particle size distribution of the coating film after kneading are shown by the weight on the cumulative sieve in FIG. FIG. 2 shows the viscosity of the base material resin and the particle size distribution of the coating film after kneading in terms of weight% on the cumulative screen. In Table 1, when the medium value of the particle size of the coating film is less than 100 μm, it is indicated by ◯, and when the medium value is 100 μm or more, it is indicated by x.

The coating particles are measured by melt-pressing the kneaded product with a hot press (230 ° C. or higher) and stretching it into a film. The film is photographed with a magnifying glass or a microscope to directly measure the particle size of the coating film. Regarding the particle size distribution of the finely divided coating film, when kneading with the base material resin (HEPE) D having a high viscosity, the particle size distribution of the base material resins A, B and C having a low viscosity is increased. I understand. Further, according to the graph of the cumulative sieve weight% (FIGS. 1 and 2), when the viscosity η of the base material resin is 90 or more, 60% of the coating film is fine particles by 100 μm or less when kneaded by a single-screw extruder. Has been converted. Furthermore, when kneading with a twin-screw extruder,
5% was finely divided to 100 μm or less. (Impact resistance) Each of the above kneaded products was pelletized, and a rectangular test piece of 63 × 12 × 6 mm was formed by injection molding using the pellet. Make a notch in this test piece and
STM D256 TEST METHOD A (CANT
Izod impact strength at -30 ° C was measured by ILEVER BEAM (IZOD-TYPE) TEST). In Table 1, the impact strength of the PE base material is defined as 100%, and the impact strength retention rate (%) of the test piece is shown. In Examples 3 and 4, since the mixing ratio of PP is high, the influence of PP is added. Izod impact value of PP is 50 J / m, Izod impact value of PE is 225 J / m
m. Assuming only the influence of the coating film, the Izod impact retention rate is improved.

The strength retention rate is 8 even when kneading with a uniaxial ruder using a base material resin having a low temperature Izod impact strength, η = 90 or more, which is most affected by coating film pieces existing in the resin.
It exceeds 0%. This is PP rather than the effect of the coating film.
It seems to be the influence of. Also, as the viscosity of the base material resin increases, the impact strength retention rate also increases.It can be seen from the size distribution of the coating film particles that the atomization of the coating film depends on the viscosity of the base material. .

3 and 4 show the results of measuring the impact strength in the same manner as described above for the samples obtained by kneading the crushed PP pulverized product with polyethylene mixed with polyethylene with a uniaxial or biaxial extruder. Show. Especially when kneading with a twin screw,
The composition containing 0% by weight shows that the Izod strength is remarkably improved. From FIG. 3 and FIG. 4, it is shown that the pulverized product of the coated PP with respect to the base material meets the standard value even if it is compounded at about 30% by weight, and it is possible to add up to this compounding amount. (Moldability) The kneadability of the kneaded product was evaluated based on the following items by molding the kneaded product into a fender liner by vacuum pressure forming. The evaluation criteria are moldability, the product weight variation is within 1%, and the product is free from defects such as deformation, cracks, cracks, and holes. Satisfaction of this was evaluated as ◯, molding was possible and one of the criteria was insufficient Δ, and unmoldable was evaluated as x.

The kneaded product of the comparative example could not be vacuum-pressure molded because the polymer itself had a low viscosity and good flowability. P
In order to use a kneaded product in which a coating film of a waste P bumper product is made into fine particles in injection molding, the resin surrounding in the mold may not be sufficient because of its high viscosity, so it is not preferable to use it directly in injection molding. . For use in injection molding, this kneaded product is preferably dry-blended with an injection grade product of the same resin as the base resin. The mixing ratio of the kneaded product and the base material is not important. Since they are the same resin, the kneading property is good, and it is possible to mix in an amount that does not impair the flowability of the injection grade. When the content of the kneaded product is approximately 10% by weight, a molded product having stable physical properties can be obtained without impairing the flowability of the injection grade. However, the appropriate amount of the mixing ratio is strictly different depending on the type of base material, viscosity (or flowability), type of injection grade, and viscosity (or flowability).

The type of high-viscosity thermoplastic resin base material is PE,
After changing to PP and PA, the PP bumper waste with a coating film was mixed and kneaded with a single-screw extruder. Table 2 compares the physical properties of this kneaded product with a new material of the thermoplastic resin base material. Table 2
It is also possible to use it by adding it to other resins as shown in FIG.

[0021]

[Table 2] Low temperature Izod impact strength -30 ℃ Equilibrium water temperature 23 ℃, 50% RH

[0022]

EFFECTS OF THE INVENTION According to the method of the present invention, the coating film of the resin molded product with a coating film is subjected to shearing force due to being kneaded with the high-viscosity base material to be made fine. As a result, in this kneaded product, the finely divided coating particles do not adversely affect the moldability and physical properties of the molded product even when added as a part of the molding material. Therefore, when the pulverized product of the resin molded product with a coating film is reused, the step of peeling or removing the coating film is not required, and the reuse is facilitated. Therefore, the method of the present invention can reduce the amount of new material used and bring about economic effects in raw materials and manufacturing processes.

[Brief description of drawings]

FIG. 1 is a line graph showing the weight% on the cumulative sieve of the particle size of the coating film in the resin after kneading with a twin-screw extruder.

FIG. 2 is a line graph showing the weight percentage on the cumulative sieve of the particle size of the coating film in the resin after kneading with a single-screw extruder.

FIG. 3 is a graph of changes in Izod impact when the compounding ratio of the PP bumper waste product mixed with PE is changed and kneaded with a single-screw extruder.

FIG. 4 is a graph of changes in Izod impact when the compounding ratio of PP bumper waste products mixed with PE is changed and the mixture is kneaded with a twin-screw extruder.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Yamamoto 1-1, Toyota-cho, Kariya-shi, Aichi Toyota Boshoku Co., Ltd. (72) Inventor Isao Park, 1-1-cho, Kariya-shi, Aichi Toyota Boshoku Co., Ltd. (72) Inventor Shigetoshi Sugiyama 1 41, Nagachote, Nagakute-cho, Aichi-gun, Aichi Prefecture 1 of Toyota Central Research Institute Co., Ltd. (72) Inventor Norio 41, Nagakute, Nagakute-cho, Aichi-gun, Aichi Prefecture 1 share Company Toyota Central Research Institute (72) Inventor Shoichi Suzuki, Aichi Prefecture, Nagakute-cho, Aichi Prefecture, Nagatoji, 1 41, Yokomichi Toyota Central Research Institute Co., Ltd. (56) Reference JP-A-7-228722 (JP, A) Special Kaihei 7-60819 (JP, A) JP 6-134757 (JP, A) JP 5-92430 (JP, A) JP 7-233263 (JP, A) JP Hei 7-164443 (JP, A) JP 7-117052 (JP, A) JP 6-100726 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29B 7 / 00-11/14 B29B 13/00-15/06 B29B 17/00-17/02 C08J 11/00-11/28 C08L 1/00-101/14 B09B 3/00-5/00

Claims (2)

(57) [Claims] 1. A crushed product of a resin molded product with a coating and 200 ° C.
A mixture with a thermoplastic matrix resin having a viscosity of η = 90 poise (g / cm · sec) or more is kneaded and extruded to form a coating film of a resin molded product with a coating film on the moldability and physical properties of the thermoplastic matrix resin. A method for making a paint film of a resin-molded article with a paint film, which is characterized in that the paint film is miniaturized to such an extent that it does not affect the coating film. 2. A resin molded product with a film according to claim 1, wherein the resin molded product with a film is a kneaded product of a polypropylene resin and an amorphous polyolefin resin, and the thermoplastic matrix resin is a polyethylene resin. Method for making coating film fine.