JPH0995567A - Resin composition prepared by using coated resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin compsn. which is prepd. by recycling a polyolefin resin molding and which can efficiently give a molding excellent in impact resistance and mechanical strengths even when prepd. from a coated molding usually considered to be difficult to recycle by adding a small amt. of an additive. SOLUTION: This resin compsn. comprises 100 pts.wt. crushed coated polyolefin resin molding and 2-15 pts.wt. modified polypropylene resin obtd. by grafting an unsatd. carboxylic acid or its deriv. onto a polypropylene resin in the presence of a freeradical polymn. initiator, subject to the condition that the polypropylene resin mainly comprises propylene-derived structural units and the modified polypropylene resin contains 0.1-20wt.% structural units derived from the unsatd. carboxylic acid or its deriv.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition, and more particularly to a resin composition for reusing scrap materials for automobile bumpers made of a coated polyolefin resin composition.

[0002]

2. Description of the Related Art Bumpers for automobiles are required to have very high impact resistance, and polyolefin resin compositions, mainly propylene polymers, ethylene-propylene copolymer rubbers,
Those containing talc are widely used, and various ones have been proposed (for example, JP-A-53-55952, JP-A-53-64257, and JP-A-57-5).
5952, JP-A-57-159841 and JP-A-58-111846). In addition, many automobile bumpers are painted to enhance their design in addition to satisfying their performance. By the way, in recent years, in particular, environmental issues and resource protection have been emphasized,
Various products, especially automobile parts, are required to be reused (recycled). As a method for recycling an automobile bumper made of a coated polyolefin resin composition, the recovered resin molded product is crushed by a crusher and used as a raw material for molding, or the crushed product is further extruded. It is a general method to pelletize and use as a raw material for molding.

[0003]

However, when it is used as a recycled material by such a method, it has a poor compatibility between the paint-based resin and the polyolefin-based resin, and thus is composed of a resin composition that can be reused. There is a problem that the impact resistance of the molded product decreases. Therefore, it is difficult to use the recycled material as it is for parts that require impact resistance. Then, as a method for improving the impact resistance of a molded product made of a resin composition using a waste material of a painted polyolefin resin automobile part, JP-A-5-154861 is known.
The methods described in JP-A-5-169479 and JP-A-5-169479 are known. However, the above-mentioned method requires at least 76 parts by weight of various materials to be mixed for improving impact resistance with respect to 100 parts by weight of the waste material to be reused. Therefore, the amount of waste material used is relatively small and the cost increases. Therefore, it is difficult to completely dispose of a large amount of waste material that occurs or is generated, and it is not very effective as a method for recycling the waste material.

The present invention has been made in order to solve the above-mentioned problems, and is a resin composition in which a polyolefin-based resin molded product is reused, and which has a coating which has been conventionally difficult to reuse. Even if there is a small amount of an additive, it is an object of the present invention to provide a resin composition which enables a molded product with high efficiency and excellent impact resistance and mechanical strength.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a specific acid-modified polypropylene-based resin is used as a scrap material for automobile bumpers made of a coated polyolefin-based resin composition. It was found that by blending at a specific weight ratio, the impact resistance of the molded product made of the obtained resin composition is greatly improved, and an injection molded product excellent in mechanical properties such as rigidity and heat resistance is obtained. That is, in the present invention, 100 parts by weight of a pulverized product of a coated polyolefin-based resin molded product, and a polypropylene-based resin having propylene as a main polymer constituent unit, an unsaturated carboxylic acid or a derivative thereof is present as a radical initiator. A resin composition comprising 2 to 15 parts by weight of a polypropylene-based resin modified by graft polymerization below (hereinafter referred to as an acid-modified polypropylene-based resin), which is an unsaturated carvone in the polypropylene-based resin. The resin composition contains 0.1 to 20 parts by weight of units derived from an acid or a derivative thereof. In the present invention, an automobile bumper is particularly preferably used as the coated polyolefin resin molded product.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. First, a waste material (hereinafter also referred to as a waste material) of an automobile bumper made of a painted polyolefin resin composition for reuse will be described. [Waste Material] As the waste material in the present invention, a polyolefin resin molded article having a surface coated with a paint resin such as an acrylic resin, a polyurethane resin or an unsaturated polyester resin can also be applied. The proportion of the coating resin contained in the waste material is 5% by weight or less, preferably 3% by weight or less. This is because if the proportion of the coating resin exceeds 5% by weight, the effect of improving impact resistance is small. In order to reuse the waste material, a crushing process is first performed for convenience of mixing. The size of the pulverized waste material can be set as appropriate, but a maximum length of 0.1 mm to 10 mm is preferable because mixing is easy. Further, as the polyolefin resin molded product,
A wide variety of things are applied, automobile parts and home appliances,
Furniture, miscellaneous goods, etc. are applied, and for example, for automobile parts, there are exterior parts such as bumpers, spoilers, side moldings, instrument panels, interior parts such as door linings, and the like.

The present invention enables the reuse of even a painted polyolefin resin composition which has been difficult to recycle in the past, and is repainted. As a matter of course, the present invention can be applied to a polyolefin resin composition that does not exist.

[Acid-modified polypropylene-based resin] The acid-modified polypropylene-based resin used in the present invention comprises a polypropylene resin and a radical-polymerizable anhydride. The radical-polymerizable anhydride as used herein refers to a compound having at least one radical-polymerizable unsaturated bond and at least one acid-anhydride group in the molecule, and capable of introducing an acid anhydride into the molecule by polymerization. . As typical examples of such compounds, maleic anhydride, itaconic anhydride, endic acid anhydride, citraconic anhydride, 1-butene-3,4-dicarboxylic acid anhydride, at the terminal having at most 18 carbon atoms Examples thereof include alkanyl succinic anhydride having a double bond and alkadienyl succinic anhydride having a double bond at the terminal having at most 18 carbon atoms. These may be used in combination of two or more kinds at the same time. Of these, maleic anhydride and itaconic anhydride are particularly preferable.

The proportion of the units derived from the radical-polymerizable acid anhydride in the acid-modified polypropylene resin is 0.1% by weight.
Must be in the range of ~ 20% by weight. When the proportion of the radical-polymerizable acid anhydride is less than 0.1%, the effect of improving the compatibility with the coating resin contained in the waste material is not sufficient and the effect of improving the impact resistance is not exhibited. If the composition ratio exceeds 20% by weight, the impact resistance of the polypropylene resin is lost, which is not preferable. The polypropylene resin used in the present invention is a propylene homopolymer, a block copolymer with ethylene and / or an α-olefin containing propylene as a main component, or an ethylene and / or ethylene containing propylene as a main component.
Alternatively, it is a random copolymer with an α-olefin. In both of these block copolymers and random copolymers, the copolymerization ratio of ethylene and α-olefin is 20% by weight or less, preferably 15% by weight or less, as their total amount.

The carbon number of the α-olefin is 4-12.
It is preferred that Examples of such α-olefins include butene-1, hexene-1, 4-methylhexene-1, and octene-1. From the viewpoint of enhancing rigidity, a propylene homopolymer is preferable. This polypropylene resin melt flow rate (MFR: AS
According to TM-D1238, using a load of 2.16 kg, 2
(Measured at 30 ° C.) is preferably 0.01 to 100 g / 10 min from the viewpoint of moldability and mechanical properties of the obtained molded product,
More preferably 0.01 to 80 g / 10 min, 0.05
More preferably, it is -80 g / 10 min.

The acid-modified polypropylene-based resin of the present invention is produced by using the polypropylene-based resin and unsaturated carboxylic acid in the above-mentioned proportions and treating them in the presence of at least one free radical initiator (heating). To be done.
At this time, the polypropylene resin, the unsaturated carboxylic acid and the free radical initiator may be treated while being mixed, but after dry blending in advance, the mixture is melted using a mixer such as a screw extruder, a kneader or a Banbury mixer. A more uniform composition can be obtained by kneading. If this treatment is carried out under a too high temperature condition, the polypropylene resin may deteriorate. However, in order to graft-polymerize the polypropylene resin and the unsaturated carboxylic acid used, depending on the type of the free radical initiator used,
It is desirable to carry out at 160 to 300 ° C, and further at 170 to 280 ° C.

The acid-modified polypropylene resin used in the present invention is preferably produced in the presence of at least one free radical initiator under the above reaction conditions. Examples of free radical initiators include oxygen; dialkyl peroxides such as di-t-butyl peroxide, t-butyl cumyl peroxide and dicumyl peroxide; acetyl peroxide, i-butyl peroxide, octanoyl peroxide and the like. Peroxycarbonates such as dialkyl peroxide, di-i-propylperoxycarbonate, and di-2-ethylhexylperoxycarbonate;
Peroxyesters such as t-butylperoxypivalate and t-butylperoxylaurate; ketone peroxides such as methylethylketone peroxide and cyclohexanone peroxide; 1,1-bis-t-butylperoxycyclohexane, 2,2 Examples include peroxyketals such as bis-t-butylperoxyoctane; hydroperoxides such as t-butylhydroperoxide and cumene hydroperoxide; azo compounds such as 2,2-azo-i-butyronitrile.

[Composition Ratio] The composition ratio of the above components used in the present invention is 2 to 15 parts by weight of the acid-modified polypropylene resin with respect to 100 parts by weight of the waste material, and 3 to 15 parts.
Weight part is preferable, and especially 3 to 13 weight part is desirable. If the composition ratio of the acid-modified polypropylene resin to the waste material of 100 parts by weight is less than 2 parts by weight, the effect of improving the impact resistance is not sufficient. On the other hand, if it exceeds 15 parts by weight, not only the effect of improving the impact resistance corresponding to the blending amount cannot be obtained, but also the impact resistance is deteriorated, which is not preferable.

[Blending] The waste material and the acid-modified polypropylene resin may be blended by uniformly mixing the respective compositions. In this case, antioxidants, heat stabilizers, light stabilizers, plasticizers, antistatic agents, flame retardants, lubricants, foaming agents, cross-linking agents, colorants, pigments, inorganics commonly added in the field of polyolefin resins. You may add various additives, such as a filler, in the range which does not impair the property which each composition or synthetic resin has substantially. Further, various synthetic resins can be added as required. For mixing each composition, a method generally used in the field of synthetic resins may be applied, and as a mixing method, a method of dry blending using a mixer such as a tumbler, a ribbon blender or a Henschel mixer or a screw method. Extruder, kneader,
A method of melt-kneading using a mixer such as a Banbury mixer can be mentioned. At this time, a more uniform composition can be obtained by dry-blending the composition in advance and further melt-kneading the resulting mixture.

[Molded Article] A molded article obtained by using the resin composition of the present invention can be obtained by various molding methods generally used in the field of synthetic resins. Among them, the injection molding method has high molding efficiency. preferable. Even in the case of the above-mentioned melt-kneading, it is necessary to carry out at a temperature at which the polyolefin resin melts even when molding a molded body, but if carried out at a higher temperature than necessary, the polyolefin resin may be thermally decomposed. The melt-kneading temperature and molding temperature are 18
It is set to 0 to 270 ° C, preferably 180 to 250 ° C. The molded product obtained by the resin composition of the present invention,
The paint-based resin is mixed inside, but the impact strength is greatly improved compared to the original waste material.

In the resin composition of the present invention, by adding a small amount of acid-modified polypropylene resin to the waste material and kneading the mixture, the compatibility of the paint resin and the polyolefin resin in the waste material is improved, so that the impact resistance is improved. It is thought that it will be greatly improved. That is, the compatibility is increased by expressing the adhesive property of the acid-modified polypropylene resin at the interface between the paint resin and the polyolefin resin.

[0017]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples. As shown in Table 1, 100 parts by weight of waste material was dry-blended with 4 kinds of acid-modified polypropylene-based resins in advance for 3 minutes using a tumbler. Each of the obtained mixtures was melt-kneaded at a resin temperature of 200 ° C. using a vented twin-screw extruder (diameter 30 mm) to produce pellet-shaped resin compositions. Further, the obtained pellets of each resin composition were injection-molded at a resin temperature of 210 ° C. using an injection molding machine having a mold clamping force of 100 tons to prepare test pieces for each test shown below.

Here, as the used scrap material, a paint-made polypropylene bumper collected from a scrap car of an automobile (manufactured by Honda Motor Co., Ltd.) was crushed by a crusher. In addition, the physical properties of the waste materials are MFR 11g / 10mi
n, the flexural modulus was 9900 kg / cm ² , and the falling weight impact strength was 125 kg-cm. Further, a urethane coating film was mixed in the waste material by 0.9% by weight. The ethylene copolymer used is shown below. Acid-modified polypropylene-based resin (A) Polypropylene homopolymer (MFR: 0.5 g / 10 min) 100 parts by weight Maleic anhydride 1.5 parts by weight Di-t-butyl peroxide 0.5 parts by weight-Acid-modified polypropylene-based resin Resin (B) Propylene-ethylene block copolymer (MFR: 0.1 g / 10 min, ethylene content: 10% by weight) 100 parts by weight Maleic anhydride 5 parts by weight Dicumyl peroxide 1.2 parts by weight Acid-modified polypropylene Resin (C) Propylene-ethylene block copolymer (MFR: 3.5 g / 10 min, ethylene content: 8% by weight) 100 parts by weight Maleic anhydride 12 parts by weight Dicumyl peroxide 1.2 parts by weight Acid-modified Polypropylene resin (D) Propylene-ethylene block copolymer (MFR: 2.5 g / 10 min, ethylene content: 15% by weight) 1 0 parts by weight 6 parts by weight acetyl peroxide 5 parts by weight of maleic anhydride

For each resin composition, the melt flow rate (hereinafter, also referred to as MFR), flexural modulus, falling weight impact strength, and heat deformation temperature were measured. Table 1 shows the measurement results. Melt flow rate is according to ASTM-D1238,
It was measured at 230 ° C. with a load of 2.16 kg. The flexural modulus is 25 in accordance with ASTM-D790.
It was measured under the condition of mm / min. The method of measuring the falling weight impact strength is as follows. First, a 60 × 60 × 3.2 mm flat plate molded from each material by injection molding is used as a test piece, and this is placed on a pipe-shaped test stand with an outer diameter of 48 mm, an inner diameter of 44 mm, and a height of 50 mm, and on top of that. Place a hammer with a radius of 1/2 inch. Then, under the condition of −30 ° C., a weight of 3 kg was naturally dropped from an arbitrary height, and the height at which the test piece was broken was measured. Height when destroyed (cm) x 3 (kg)
Is shown in the table as falling weight impact strength. Heat distortion temperature is AS
According to TM-D648, the load was measured under the condition of 4.6 kg / cm ² .

As comparative examples, resin compositions having different compounding ratios were prepared and the same tests were conducted. The measurement results are shown in Table 2.

[Table 1]

[Table 2]

From Tables 1 and 2, when the waste material as it is (Comparative Example No. 1) has a particularly low drop weight impact strength, the resin composition of this example has a flexural modulus, a drop weight impact strength,
It can be seen that the heat distortion temperature is excellent. Further, the falling weight impact strength of the comparative example Nos. 2, 3 and 5 having a small compounding ratio of the acid-modified polypropylene resin and the falling weight impact strength of the comparative example No. 4 having a large compounding ratio remain small.

[0022]

EFFECTS OF THE INVENTION The molded product obtained from the resin composition of the present invention has a paint resin mixed therein, but the impact strength is greatly improved as compared with the original waste material. .
Therefore, the resin composition according to the present invention can be used for molded articles requiring impact resistance, including automobile parts,
It can be reused as a molded product for various purposes such as electrical products and daily sundries. In particular, since the present invention uses a small amount of ethylene-based copolymer and a large amount of waste material,
The amount of waste materials used is relatively large, which is economically advantageous,
This technology is also excellent in terms of environmental issues and resource protection.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI technical display location C08L 51:06) (72) Inventor Akiko Katagiri 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Electric Works Co., Ltd. Kawasaki Plastics Research Institute (72) Inventor Kazuo Ito 1-13-9 Shiba Daimon, Minato-ku, Tokyo Showa Denko Co., Ltd. (72) Inventor Atsushi Takeuchi 1-4-1 Chuo Wako, Saitama Prefecture Stock Association Incorporated in Honda R & D Laboratories (72) Inventor Minoru Makuda 1-4-1 Chuo, Wako, Saitama Stock Company Incorporated in Honda R & D Laboratories (72) Inventor Hitoshi Ogane 1-4-1 Chuo, Wako, Saitama Incorporated in Honda R & D Co., Ltd. (72) Kenji Hamabe, Kenji Hamabe 1-4-1 Chuo, Wako, Saitama Prefecture Incorporated in Honda R & D Co., Ltd. (72) Osamu Aoki Central 1 in Wako, Saitama Eyes fourth No. 1 stock company Honda intra-technology Research Institute

Claims (2)

[Claims] 1. A pulverized product of a coated polyolefin resin molded product, 100 parts by weight, a polypropylene resin containing propylene as a main polymer constituent unit, and an unsaturated carboxylic acid or a derivative thereof in the presence of a radical initiator. Is a resin composition containing 2 to 15 parts by weight of a polypropylene-based resin modified by graft-polymerization with 1., wherein the proportion of units derived from an unsaturated carboxylic acid or its derivative in the polypropylene-based resin is 0. 1 to 20 parts by weight, a resin composition utilizing a coated resin molded product. 2. The resin composition according to claim 1, wherein the polyolefin-based resin molded product is an automobile bumper.