JP2015157920A - Coatability-improving agent for polyolefin resin, polyolefin resin composition and molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coatability-improving agent that provides a high level of coatability without loss of characteristics of polyolefin resin.SOLUTION: A coatability-improving agent for polyolefin resin is an alkyl methacrylate polymer (A) comprising an alkyl methacrylate (a) unit of 50 mass% or more. A polyolefin resin composition comprises the coatability-improving agent for polyolefin resin and polyolefin resin (B). A polyolefin resin molded article is obtained by molding the polyolefin resin composition.

Description

  The present invention relates to a coating property improving agent for polyolefin resins, a polyolefin resin composition containing the coating property improving agent, and a polyolefin resin molded product obtained by molding the polyolefin resin composition.

  Polyolefin resin has features such as low cost, low specific gravity, and high rigidity, and is a general-purpose resin widely used for automobile members and the like.

  However, since the polyolefin resin has low polarity, the coating property, the printability, and the film adhesion are low, and it is difficult to apply the coating to the molded product after the molding process.

  As a method for improving the above-mentioned problems, Patent Document 1 discloses that a polyolefin resin is blended with a resin modifier obtained by graft polymerization of an alkyl methacrylate having a specific structure to a rubbery polymer, thereby improving the dyeability of the polyolefin resin. Improvement techniques have been proposed. However, the above technique is a technique that contains a rubbery polymer as an essential component, and the rigidity of the polyolefin resin is reduced by including the rubbery polymer, and a specific acrylic component that contributes to the improvement of dyeability in the graft part. Therefore, there was a problem that the acrylic resin component was not sufficiently dispersed in the polyolefin resin, and the dyeability and paint adhesion were not sufficiently improved.

  As a technique for improving the dispersibility of an acrylic resin in a polyolefin resin and improving dyeability and paint adhesion, Patent Document 2 discloses a polymer “macromonomer” having a polymerizable unsaturated group and a single structure having a specific structure. There has been proposed a technique for improving coating adhesion of a molded body by kneading a polymer obtained by radical polymerization by mixing a monomer with a polyolefin resin. However, the above technique increases the viscosity of the mixture of macromonomer and vinyl monomer, so solution polymerization must be selected as the polymerization method, and an odor is generated during extrusion by the organic solvent remaining in the recovered product. There has been a problem, and there has been a demand for a modifier that is polymerized only with a vinyl monomer that can be recovered by a simple polymerization method such as emulsion polymerization or suspension polymerization with little residue.

  Patent Document 3 discloses a technique capable of imparting a certain compatibility to a polyolefin resin by preparing an alkyl methacrylate having an alkyl group having 2 or more carbon atoms to a predetermined molecular weight. According to the present technology, the alkyl metacrete can improve the dispersibility of the polyolefin resin and polar fillers. However, this patent document does not describe the improvement of the coating properties of the polyolefin resin.

JP 2005-132972 A JP 2006-2079 A WO2011-096596

  An object of the present invention is to provide a paintability improving agent that imparts a high degree of paintability without losing the properties of a polyolefin resin.

  The present invention relates to a coating improver for polyolefin resins, which is an alkyl methacrylate polymer (A) containing 50% by mass or more of an alkyl methacrylate (a) unit. The present invention also relates to a polyolefin resin composition comprising the paintability improving agent and a polyolefin resin. Furthermore, this invention relates to the molded object obtained by shape | molding the said polyolefin resin composition.

  By using the coating property improving agent of the present invention, the coating property of the polyolefin resin can be improved.

The paintability improving agent of the present invention is an alkyl methacrylate polymer (A) containing 50% by mass or more of an alkyl methacrylate (a) unit.
In the present invention, the alkyl methacrylate polymer (A) contains 50% by mass or more of alkyl methacrylate (a) units in 100% by mass of all monomer units, and preferably 70% by mass or more. More preferably, the content is 85% by mass or more. When the content of the alkyl methacrylate (a) unit is 50% by mass or more, the paintability improving effect is excellent.

  Examples of the alkyl methacrylate (a) include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, and n-hexyl. Mention may be made of methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate and 2-hydroxyethyl methacrylate. These alkyl methacrylates may be used individually by 1 type, and may use 2 or more types together.

  The alkyl methacrylate polymer (A) may contain 50% by mass or more of an alkyl methacrylate unit having an alkyl group having 1 to 8 carbon atoms as an alkyl methacrylate (a) unit in 100% by mass of all monomer units. preferable. By containing an alkyl methacrylate unit having an alkyl group having 8 or less carbon atoms, a high powder handling property can be imparted to the coating property improver obtained.

  The alkyl methacrylate polymer (A) may contain 50% by mass or more of an alkyl methacrylate unit having an alkyl group having 1 to 4 carbon atoms as an alkyl methacrylate (a) unit in 100% by mass of all monomer units. More preferably, it is particularly preferable to contain 50% by mass or more of methyl methacrylate (a1) units.

The alkyl methacrylate polymer (A) may contain a monomer (b) unit other than the alkyl methacrylate (a) unit, if necessary.
Examples of these other monomers (b) include aromatic vinyl monomers such as styrene, α-methylstyrene and chlorostyrene; vinyl cyanide monomers such as (meth) acrylonitrile; vinyl methyl ether, Examples thereof include vinyl ether monomers such as vinyl ethyl ether; vinyl carboxylate monomers such as vinyl acetate and vinyl butyrate; olefin monomers such as ethylene, propylene and butylene; and aromatic methacrylates such as phenyl methacrylate and benzyl methacrylate. These other monomers (b) may be used individually by 1 type, and may use 2 or more types together. Among the other monomers (b), it is preferable to use aromatic methacrylate (b1) because it is excellent in paintability improving effect. Particularly, aromatic methacrylate (b1) is copolymerized with methyl methacrylate (a1). It is preferable to use it.

  In the present invention, the mass average molecular weight of the alkyl methacrylate polymer (A) is not particularly defined, but is preferably in the range of 5,000 to 90,000. When the mass average molecular weight of the alkyl methacrylate polymer (A) is 5,000 or more, the resulting paintability-imparting agent is excellent in powder handleability. If the mass average molecular weight is 90,000 or less, a sufficient paintability improving effect can be expected when blended with a polyolefin resin. The mass average molecular weight of the alkyl methacrylate polymer (A) is more preferably in the range of 5,000 to 70,000, and still more preferably in the range of 5,000 to 50,000. The mass average molecular weight of the alkyl methacrylate polymer (A) of the present invention can be measured using gel permeation chromatography.

  The method for adjusting the mass average molecular weight is not particularly limited, and examples thereof include a method for adjusting the amount of polymerization initiator and a method for adjusting the amount of chain transfer agent.

Examples of the chain transfer agent include mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, n-hexyl mercaptan, n-butyl mercaptan; carbon tetrachloride, ethylene bromide. And halogen compounds such as α-methylstyrene dimer.
These chain transfer agents may be used individually by 1 type, and may use 2 or more types together.

  The amount of the chain transfer agent used can be appropriately adjusted according to the weight average molecular weight of the alkyl methacrylate polymer (A), the type of chain transfer agent used, the composition ratio of the monomers, and the like.

  Examples of the polymerization method of the alkyl methacrylate polymer (A) include known polymerization methods such as emulsion polymerization, soap-free emulsion polymerization, fine suspension polymerization, suspension polymerization, bulk polymerization, and solution polymerization. Among these polymerization methods, water-based polymerization such as emulsion polymerization and suspension polymerization is used because of the point of odor when blending the coating property improver into the polyolefin resin and the point that powder recovery is easy and economical. Preferably there is. Auxiliaries necessary for the polymerization can be appropriately used. For example, a polymerization initiator, an emulsifier, a dispersant, a chain transfer agent, and an antifoaming agent can be used.

  The alkyl methacrylate polymer (A) can be used as a coating property improving agent that improves the coating property of the polyolefin resin by kneading the polyolefin resin.

  The alkyl methacrylate polymer (A) can be used alone or in combination with two or more alkyl methacrylate polymers (A) having different molecular weights, compositions, polymerization methods and the like. As a combination of the alkyl methacrylate polymer (A), it is preferable to use a combination of two or more polymers containing 50% by mass or more of an alkyl methacrylate (a1) unit having an alkyl group having 1 to 8 carbon atoms. It is more preferable to use a combination of a polymer containing 50% by mass or more of a unit and a polymer containing 50% by mass or more of an alkyl methacrylate unit having an alkyl group having 2 to 8 carbon atoms, and a methyl methacrylate unit of 50% by mass. It is more preferable to use a combination of a polymer containing at least 50% by mass and a polymer containing at least 50% by mass of an alkyl methacrylate unit having an alkyl group having 4 carbon atoms, and a polymer containing at least 50% by mass of methyl methacrylate units. And 50% by mass or more of isobutyl methacrylate units It is particularly preferred to use a combination of that polymer. When a polymer is used in combination, a higher paintability improving effect can be obtained than when the polymer is used alone.

  In the present invention, the polyolefin resin (B) refers to a homopolymer of an olefin monomer or a copolymer containing 50% by mass or more of an olefin monomer. Examples of the olefin monomer include ethylene, propylene, 1-butene, 1-hexene, 1-decene, 1-octene, and 4-methyl-1-pentene. Specific examples of homopolymers of olefin monomers or copolymers containing 50 mass% or more of olefin monomers include, for example, low density polyethylene, high density polyethylene, polypropylene, ethylene / propylene copolymers, Examples include polymethylpentene, polybutene, and mixed resins thereof.

  The polyolefin resin composition of the present invention comprises a coating property improver that is the alkyl methacrylate polymer (A) and a polyolefin resin (B).

  The content of the alkyl methacrylate polymer (A) in the polyolefin resin composition can be arbitrarily set according to the target level of paintability. The alkyl methacrylate polymer (A) is preferably in the range of 0.1 to 30% by mass in a total of 100% by mass of the alkyl methacrylate polymer (A) and the polyolefin resin (B). When the content of the alkyl methacrylate polymer (A) is 0.1% by mass or more, a high paintability improving effect can be imparted to the obtained molded body. When the content of the alkyl methacrylate polymer (A) is 30% by mass or less, the paintability can be improved without significantly degrading the properties of the polyolefin resin. The content of the alkyl methacrylate polymer (A) is preferably 1 to 25% by mass, and more preferably 5 to 20% by mass.

  As a kneading method of the polyolefin resin composition of the present invention, known melt kneading such as extrusion kneading and roll kneading can be used.

  Although it can set suitably as melt-kneading temperature according to the kind of polyolefin resin (B), as melt-kneading temperature of general polyolefin resin, 160-280 degreeC is preferable and it is 180-240 degreeC. It is more preferable.

  If necessary, the polyolefin resin composition of the present invention may further contain additives such as fillers, flame retardants, stabilizers, lubricants and foaming agents.

  The molded product of the present invention is obtained by molding the polyolefin resin composition of the present invention.

  As a molding method of the molded body of the present invention, a known molding method can be used, and examples thereof include extrusion molding, injection molding, calendar molding, blow molding, thermoforming, foam molding, melt spinning and the like.

  The molded body of the present invention has characteristics that can be easily painted, and is suitable for sheet materials, film materials, automobile members, household appliance members, medical members, building members, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In the examples, “parts” and “%” indicate “parts by mass” and “% by mass”.

(1) Mass average molecular weight Gel permeation chromatography (model name “HLC-8220”, manufactured by Tosoh Corp.), column (trade name “TSK”) using the tetrahydrofuran-soluble content of the alkyl methacrylate polymer (A) as a sample. -GEL SUPER HZM-M "(manufactured by Tosoh Corporation) was used under the conditions of eluent tetrahydrofuran and measurement temperature 40 ° C.
The mass average molecular weight was determined from a calibration curve using standard polystyrene.

(2) Paintability evaluation “News Play Lacquer Round Pattern (Black)” (trade name, manufactured by Rock Paint Co., Ltd.) was sprayed on the molded bodies described in Examples and Comparative Examples as paint for evaluating paintability at room temperature. After drying for 5 hours, it was further dried at 60 ° C. for 2 hours to obtain a test piece for paintability test. 10 cm of a commercially available adhesive tape was affixed to the coated surface, and the adhesion of the paint applied when the tape was peeled was judged according to the following criteria.
◎: Paint does not peel at all ◯: 80% or more and less than 100% of paint remains on the test piece without peeling △: 50% or more and less than 80% of the paint remains on the test piece without peeling ×: 20% of the paint Less than 50% remains on the test piece without peeling. Xx: Less than 20% of the coating remains on the test piece.

[Production Example 1] Production of paintability improver (I) The following components were charged into a heatable reaction vessel equipped with a thermometer, a nitrogen introduction tube, a reflux condenser, and a stirring device, and the reaction vessel was filled with nitrogen. The temperature was raised to 80 ° C.
Deionized water 200 parts Dispersant 0.3 parts Sodium sulfate 0.5 part 2,2'-azobis (2-methylbutyronitrile) 0.4 part Phenyl methacrylate 20 parts Methyl methacrylate 79 parts Methyl acrylate 1 part n-Octyl Mercaptan 2 parts

  Stirring was continued for 4 hours, and the bead polymer was washed with water and dried to obtain an alkyl methacrylate polymer (I). The obtained alkyl methacrylate polymer (I) had a mass average molecular weight of 14,000. The obtained alkyl methacrylate polymer (I) was used as a coating property improving agent (I).

[Production Example 2] Production of paintability improving agent (II) In a separable flask equipped with a thermometer, a nitrogen introduction tube, a cooling tube and a stirrer, 225 parts of ion-exchanged water as a dispersion medium and sodium dodecylbenzenesulfonate as an emulsifier 2.5 parts, ferrous sulfate 0.0002 parts, ethylenediaminetetraacetic acid disodium 0.0006 parts, and ascorbic acid 0.48 parts were charged, and the inside of the container was purged with nitrogen. Next, the internal temperature was raised to 73 ° C., and 0.2 parts of cumene hydroperoxide as a polymerization catalyst, 1 part of n-octyl mercaptan, 98 parts of i-butyl methacrylate and 2 parts of n-butyl acrylate as a chain transfer agent were used. The monomer mixture was added dropwise over 1 hour, and further maintained at the same temperature for 1 hour to obtain an alkyl (meth) acrylate polymer (II) latex.

  The obtained latex was cooled to 25 ° C., dropped in 500 parts of 70 ° C. hot water containing 5 parts of calcium acetate, and then heated to 90 ° C. for coagulation. The obtained coagulated product was separated and washed, and then dried at 60 ° C. for 12 hours to obtain an alkyl (meth) acrylate polymer (II). The obtained alkyl (meth) acrylate polymer (II) had a mass average molecular weight of 30,000. The obtained alkyl methacrylate polymer (II) was used as a coating property improving agent (II).

Example 1
As polyolefin resin (B), 15 parts of the above-mentioned coating property improving agent (I) was blended with 85 parts of polypropylene resin “NOVATEC FY-4” (trade name, manufactured by Nippon Polypropylene Co., Ltd.) and mixed by hand blending. Then, using a φ30 mm co-directional twin screw extruder (manufactured by Plastic Engineering Laboratory Co., Ltd., L / D = 30), melt extrusion kneading under the conditions of a screw rotation speed of 200 rpm and a cylinder temperature of 200 ° C., for coating property evaluation A polyolefin resin composition was obtained. The obtained polyolefin resin composition was dried at 80 ° C. for 12 hours, and using a single screw extruder (manufactured by GM Engineering, L / D = 30) equipped with a T die, the screw rotation speed was 20 rpm. The film was formed to a thickness of 500 μm and a width of 10 cm under the conditions of a cylinder temperature of 200 ° C. and a T die temperature of 210 ° C. to obtain a film-like molded body for coating property evaluation. The obtained molded body was coated by the above method and subjected to evaluation. The evaluation results are shown in Table 1.

(Examples 2 to 4)
Kneading, film formation and evaluation were carried out in the same manner as in Example 1 except that the paintability improving agent (A) was changed to the ratio shown in Table 1. The evaluation results are shown in Table 1.

(Comparative Example 1)
Kneading, film formation and evaluation were carried out in the same manner as in Example 1 except that the paintability improving agent (A) was not blended. The evaluation results are shown in Table 1.

ＦＹ−４：ホモポリプロピレン樹脂「ノバテック ＦＹ−４」（商品名、日本ポリプロピレン（株）製、ＭＦＲ＝５ｇ／１０ｍｉｎ）

FY-4: Homopolypropylene resin “Novatech FY-4” (trade name, manufactured by Nippon Polypropylene Co., Ltd., MFR = 5 g / 10 min)

  As is apparent from Table 1, the polyolefin resin composition containing the coating property improving agent (Examples 1 to 4) of the present invention is excellent in coating property. On the other hand, the comparative example 1 which does not contain a coating property improving agent has remarkably bad coating property. Therefore, it can be seen that the paintability improving agent of the present invention exhibits an excellent effect as a polyolefin resin paintability improving agent.

The paintability improving agent of the present invention greatly improves the paintability of a molded product when blended with a polyolefin resin. For this reason, the coating property of polyolefin resin used for a sheet material, a film material, a member for automobiles, a member for household appliances, an OA equipment member, an electric wire covering material, etc. can be improved, and it is suitable for these uses.

Claims (8)

  A coating property improving agent for polyolefin resin, which is an alkyl methacrylate polymer (A) containing 50% by mass or more of an alkyl methacrylate (a) unit.   The coating property improvement for polyolefin resins according to claim 1, wherein the alkyl methacrylate polymer (A) contains 50% by mass or more of an alkyl methacrylate unit having an alkyl group having 1 to 8 carbon atoms as the alkyl methacrylate (a) unit. Agent.   The coating property improving agent for polyolefin resins according to claim 1 or 2, wherein the alkyl methacrylate polymer (A) contains 50% by mass or more of methyl methacrylate (a1) units as alkyl methacrylate (a) units.   The coating property improving agent for polyolefin resins according to any one of claims 1 to 3, wherein the alkyl methacrylate polymer (A) further contains an aromatic methacrylate (b1) unit.   The coating property improvement for polyolefin resins according to claim 1, wherein the alkyl methacrylate polymer (A) contains 50 mass% or more of an alkyl methacrylate unit having an alkyl group having 2 to 8 carbon atoms as the alkyl methacrylate (a) unit. The coating property improving agent for polyolefin resins according to claim 3 or 4, further comprising an agent.   The alkyl methacrylate polymer (A) further contains a coating property improving agent for polyolefin resin according to claim 1, further comprising 50% by mass or more of isobutyl methacrylate units as alkyl methacrylate (a) units. The coating property improving agent for polyolefin resin as described.   A polyolefin resin composition comprising the polyolefin resin coating property improving agent according to any one of claims 1 to 6 and a polyolefin resin (B). A polyolefin resin molded article obtained by molding the polyolefin resin composition according to claim 7.