JPS5950171B2 - Method for manufacturing surface-modified polyolefin molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a surface-modified polyolefin molded article, and the molded article obtained using this as a raw material is an olefin resin that is easy to paint and can withstand temperatures of 100°C. The purpose is to provide molded products using the base material.

Among general-purpose thermoplastic resins, high-density polyethylene and polypropylene can withstand temperatures of 100°C, but because they are chemically inert and do not have polar groups, secondary processing such as painting and adhesion is difficult and complicated. Requires pre-treatment.

There are paints for polyolefins, but they are special paints and have limited film performance. On the other hand, styrene resins, AS resins, vinyl chloride resins, ABS resins, and the like can be easily subjected to secondary processing, but cannot withstand temperatures of 100°C. Moreover, the solvents used for coating with these resins are also limited, and therefore the performance of the resulting coating film is also limited depending on each resin. In recent years, urea resin or melamine resin has been used as the base for lacquerware instead of wood, but ARS is used as the base for direct mass-produced tableware due to its sanitary safety and productivity.
A large amount of resin is used.

However, ABS resin cannot withstand high-temperature baking of 100 degrees Celsius or more during painting, nor can it withstand hot water. In view of these circumstances, there is a need for a lacquerware base that is easy to paint and that can withstand high-temperature baking and hot water. In order to meet the above-mentioned demand, the present inventors are currently studying various methods for surface modification of polyolefin molded products that are inherently heat resistant. It was previously thought that polypropylene and polyethylene would cause delamination, making it impossible to obtain a molded product that could be put to practical use. However, it was discovered that when polypropylene and polyethylene are mixed together in the presence of rubber, delamination does not occur during injection molding, and further investigation has been conducted. As a result, when the rubbery substance is finely dispersed in the olefin resin, layer delamination occurs on the surface of molded products made from compositions containing the same amount of styrene resin or acrylic resin as the olefin resin. We have discovered a previously unknown phenomenon in which no

In addition, the obtained molded product can withstand temperatures of 100°C or higher, and with simple solvent treatment, the paintability of the molded product surface with paints containing thermoplastic resin as the main component is improved, and the molded product can be easily painted. The present inventors have discovered that the use of chlorinated polyolefin significantly improves the adhesion strength of the coating film, leading to the present invention. That is, the present invention provides olefin resin 10
3 parts of solvent-soluble rubber that is incompatible with the resin
~20 parts and styrene resin or acrylic resin (hereinafter the two are collectively referred to as styrene resin, etc.) 5 to 10 parts
A surface-modified polyolefin molded product characterized in that the surface of the molded product obtained by blending 0 parts and melt-kneading and molding is treated with a chlorinated polyolefin solution containing a solvent that dissolves the olefin resin. This is a manufacturing method.

Olefin resins here include propylene homopolymers obtained by polymerizing propylene alone, copolymers obtained by copolymerizing propylene with ethylene or other α-olefins, and homopolymerization of ethylene under medium or low pressure. Alternatively, it is an ethylene homopolymer or copolymer having a density of 0.94 to 0.97 obtained by copolymerizing with other α-olefins.

Solvent-soluble rubber substances include aromatic solvents such as toluene and xylene, MEK, . Thermoplastic unvulcanized rubber that is soluble in any of the solvents commonly used in paints, such as ketones such as MIBK, esters such as ethyl acetate and butyl acetate, and alcohols such as isopropyl alcohol, or a mixed solvent thereof. For example, 1,4 polybutadiene, 1,2 polybutadiene, styrene butadiene rubber, acrylic ester rubber, etc.

The amount of rubber compounded is 3 to 2 parts per 100 parts of polyolefin.
The reason why it is set at 0 parts is because if it is less than this, when styrene resin etc. is blended, the dispersion will be poor and the molded product from the mixture will peel off, and if it is more than 20 parts, the physical properties will deteriorate significantly. The most preferred amount is 5 to 15 parts. Styrenic resins include styrene homopolymers, copolymers of styrene and methylstyrene, AS resins, ABS resins, and the like. The acrylic resin is an acrylic ester polymer, such as polymethyl methacrylate. The blending amount of these styrene resins, etc. is 5 to 100 parts per 100 parts of polyolefin; if it is less than 5 parts, it will be difficult to obtain the desired coating properties, and if it is more than 100 parts, the heat resistance will be greatly reduced. During solvent treatment, the surface of the molded product becomes rough, resulting in poor appearance after painting, and delamination occurs on the surface of the molded product. The preferred amount is 10 to 50 parts. To melt and knead these resins and rubbers, a Banbury type mixer or a twin-screw extruder with a large kneading effect is used.

The composition obtained by melt-kneading these materials can be molded by any molding method such as injection molding, extrusion molding, or blow molding.
Note that the styrene resin and the like may be added during molding. That is, these resins are added and mixed to a composition in which the rubbery material is finely dispersed, which is obtained by melt-kneading the polyolefin resin and the rubbery material in the above-mentioned kneading machine, and then melt-kneaded in the molding machine. Can be done. At this time, it is desirable to use a molding machine with a large kneading effect to prevent the molded product from delaminating. Inorganic fillers such as heavy calcium carbonate and talc, or wood flour may be blended into this composition, and rigidity and heat resistance are improved by blending these ingredients.

The chlorinated polyolefin solution for treating the surface of the molded article of the above-mentioned composition is a solution of chlorinated polypropylene, chlorinated polyethylene, or a mixture thereof, and the solvent used is an aromatic hydrocarbon solvent such as toluene or xylene,
Polyolefin-soluble solvents such as chlorinated hydrocarbon solvents such as trichrene, perchrene, and trichloropropane are preferred, but mixed solvents of these or solvents containing these as main components may also be used.

All commercially available chlorinated polyolefins are used. The appropriate concentration in the solution is several percent. In order to treat the surface of a molded article with the treatment liquid, the surface of the molded article is wetted by a force method such as spraying, dipping, or brush coating, and then dried.

A molded article made from the composition as described above has a surface that is easy to be painted, and can withstand a baking temperature of 100°C or more,
It can also withstand boiling water.

Even though a large amount of low softening point resin such as styrene resin is blended, the above-mentioned heat resistance is exhibited because the heat resistant olefin resin forms the matrix and the styrene resin etc. are finely dispersed. It is thought that this is because of this. The reason why the styrene resin and the like are dispersed without delamination is considered to be because the rubbery substance acts like a surfactant. The surface of this molded product is treated as described above using a solution in which chlorinated polyolefin is dissolved in a polyolefin-soluble solvent such as an aromatic solvent such as toluene or a chlorinated hydrocarbon solvent such as trichlene, and then painted. At this time, the adhesion strength of the coating film is significantly improved.

This treatment is industrially advantageous because it can be carried out at room temperature. The reason why a surface with good paintability can be obtained by the above-mentioned solvent treatment is that the surface of the molded product is covered with a thin film of olefin resin that forms a matrix, and this film is removed by solvent treatment. This is because the surface of the resin such as styrene resin and the rubber surface dispersed under the film are exposed.

Therefore, in the case of a molded product made from a composition in which olefin resin is blended with rubber, styrene resin, etc., the solvent-treated surface may be polystyrene depending on the type of resin such as styrene resin blended. It is possible to paint with ABS paint or ABS paint, but it is not just a solvent treatment.
When the chlorinated polyolefin is applied to the surface of a molded article by removing the surface polyolefin film by treatment with a solvent containing chlorinated polyolefin and then painting, the chlorinated polyolefin acts as a glue between the polyolefin and the coating film, and A coating film with strong adhesion that can withstand boiling tests can be obtained.

Since the base material is polyolefin, there are no restrictions on solvents like in polystyrene paints or ABS paints, and solvents with strong dissolving power can be used.Also, it can withstand high-temperature baking, so the resin content of the paint can be reduced. The selection range becomes wider, and it becomes possible to obtain coatings superior to those of these coatings. As detailed above, the manufacturing method of the surface-modified polyolefin molded product of the present invention has (1) ease of implementation, that is, in the production of the composition, it is possible to The surface treatment of the molded product is not limited by the shape of the molded product, such as flame treatment or corona discharge treatment, which are conventional surface treatment methods for polyolefin. It also does not require the use of dangerous chemicals such as oxidation treatment with a mixture of chromic acid and sulfuric acid, nor does it require complicated operations, and can be easily performed anywhere at room temperature. By combining the practical physical properties characteristic of polyolefins, such as the heat resistance and impact resistance of polypropylene, with the low cost of raw material resins, new products can be provided.

In particular, the effects of the present invention can be exhibited in composite resin molded products where resin coloring is difficult due to the blending of fillers. For the above reasons, the industrial value of the present invention is extremely large. This will be explained below using examples.

Example 1 Propylene homopolymer (melt flow index 1
4) After melt-kneading 100 parts of styrene-butadiene rubber and 10 parts of styrene-butadiene rubber (Tabprene A manufactured by Asahi Kasei Corporation) at 220 to 240°C in a continuous Banbury mixer, and forming the discharged molten resin into a plate shape with a cooling roll. Shattered.

Polystyrene (melt flow index 1, 2) was added to the resulting resin composition in various proportions, mixed in a tumbler, and then molded into test pieces according to various physical property test methods by injection molding. The physical properties of the pieces were measured.
The measurement results are shown in Table 1. Incidentally, even when the plate-shaped test pieces for the coating test were immersed in hot water at 100°C, no deformation was observed in any of them.

In addition, in the coating test, a plate-shaped test piece was coated with chlorinated polypropylene 2
A polystyrene paint (High Plus 200 manufactured by Kawakami Paint Co., Ltd.) was used to treat the product treated at room temperature with a mixed solvent of toluene and trichlorene containing 50% toluene. The results are shown in Table 1. Example 2 Propylene homopolymer (melt flow index 1
4) Melt-knead 100 parts of styrene-butadiene rubber and 100 parts of heavy calcium carbonate at a temperature of 210 to 220°C in a continuous Banbury mixer.

The discharged molten resin was pulverized into a plate shape using a cooling roll. After mixing 100 parts of the obtained resin composition and 20 parts of AS resin in a tumbler, a plate-shaped test piece was molded by injection molding, and the molded product was immersed in a toluene/triclene mixed solvent containing 2% chlorinated polypropylene at room temperature. After drying, it was painted with an acrylic paint (Acrica Bl6O manufactured by Kawakami Paint Co., Ltd.). The result of the paint film peeling test similar to Example 1 was 100/1.
00, no peeling occurred at all. Example 3 In Example 2, methacrylic resin (for injection molding) was used instead of AS resin.
Using 20 parts, the other parts were processed in the same manner to form a plate-shaped test piece.
Painted.

Claims (1)

[Claims] 1. 100 parts of olefin resin is mixed with 3 to 20 parts of a solvent-soluble rubber material that is incompatible with the resin, and 5 to 100 parts of styrene resin or acrylic resin, and the resulting molded product is melt-kneaded and molded. A method for producing a surface-modified polyolefin molded article, which comprises treating the surface with a chlorinated polyolefin solution containing a solvent that dissolves the olefin resin.