JPH0341100B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a polypropylene molded product with excellent offset printability. (Prior Art) It is well known that polyolefins such as polypropylene are inherently inert among various plastics and have poor surface properties such as printability and adhesiveness. In order to improve these defects, polyolefin molded products are subjected to pretreatment such as acid treatment, flame treatment, and corona discharge treatment, but pretreated polyolefin molded products cannot be printed using screen printing, etc. It has excellent printability with no unevenness and can print with good adhesion to the ink, but in the case of offset printing, not only does printing unevenness occur,
Adhesion with ink was poor, and polyolefin molded products had to be coated with an anchor coat. In addition, as a technique to eliminate such drawbacks, for example, as seen in Japanese Patent Application Laid-open No. 11840/1984,
A non-polar polyolefin is blended with a polymer having a polar group such as a (meth)acrylic acid ester polymer or a vinyl acetate polymer, this is molded, and the surface of this molded body is further subjected to a corona discharge treatment,
A technique is known that ensures printability and ink adhesion without requiring an anchor coat. (Problems to be Solved by the Invention) However, even with this technology, that is, blending polymers with polar groups and subjecting them to corona discharge treatment, the printability and ink adhesion are still insufficient. Therefore, further improvement was desired. (Means for solving the problem) The inventors of the present invention have established a means for solving the problem in response to such a demand. That is, the gist of the present invention is to add 0.01 to 50 parts by weight of a polar polymer and 0.05 to 2.0 parts by weight of an antistatic agent or 0.1 to 10 parts by weight of a surfactant to 100 parts by weight of a polypropylene resin, and then heat the mixture. A polypropylene molded article is obtained by subjecting a molded article obtained by molding a composition obtained by kneading to a corona discharge treatment. In the present invention, polypropylene resins include those whose main component is a propylene homopolymer or copolymer, such as crystalline polypropylene, crystalline ethylene-polypropylene block copolymer, etc.
and mixtures thereof. The polar polymers used in the present invention include a copolymer of ethylene and vinyl acetate, a partially saponified copolymer of ethylene and vinyl acetate, a copolymer of vinyl chloride and vinyl acetate, a copolymer of vinyl chloride and acrylic acid, Copolymers of fumaric acid, crotonic acid and their esters, copolymers of acrylonitrile and vinyl acetate, copolymers of ethylene and unsaturated acids or their esters, copolymers of ethylene and vinyl chloride , copolymers of polypropylene and unsaturated acids or their esters, graft polymers of polyethylene, polypropylene and unsaturated acids or their esters, copolymers of polyethylene or polypropylene and vinyl ethers, copolymers of ethylene and styrene. Examples include polymers, copolymers of ethylene and urethane, copolymers of ethylene and fluorine-containing monomers, chlorinated polyethylene, and chlorinated polypropylene. The amount of polar polymer used varies depending on its type, but is 0.01 to 50 parts by weight per 100 parts by weight of the polypropylene resin, particularly preferably 2 to 50 parts by weight.
It is 10 parts by weight. If the amount of the polar polymer is less than 0.01 parts by weight per 100 parts by weight of the polypropylene resin, no effect of improving the printability or adhesion with ink of the resulting polypropylene molded product will be observed. 50 again
If the amount is more than 1 part by weight, the mechanical properties of the polypropylene molded product will be greatly deteriorated, which is not preferable. The antistatic agents used in the present invention include primary amine salts, tertiary amine salts, quaternary ammonium compounds, cationic antistatic agents such as pyridine derivatives, sulfated oils, soaps, and nitrated esters. Oil, sulfated amide oil, sulfate ester salts, fatty alcohol, alkyl sulfate ester salt, fatty acid ethyl sulfonate, alkyl sulfonate hydrochloride, alkylnaphthalene sulfonate, alkylbenzene sulfonate, succinate ester sulfonate Anionic antistatic agents such as salts and phosphate ester salts, partial fatty acid esters of polyhydric alcohols, ethylene oxide adducts of fatty acids, ethylene oxide adducts of fatty acid amines or fatty acid amides,
Examples include ethylene oxide adducts of alkylphenols, ethylene oxide adducts of partial fatty acid esters of polyhydric alcohols, nonionic antistatic agents such as polyethylene glycol, and amphoteric antistatic agents such as carboxylic acid derivatives and imidazoline derivatives. It will be done. The amount of the antistatic agent used is 0.05 to 2.0 parts by weight, preferably 0.4 to 0.8 parts by weight, based on 100 parts by weight of the polypropylene resin. If it exceeds 2.0 parts by weight, the antistatic agent bleeds onto the surface of the polypropylene molded product, impairing its appearance, which is not preferable. Surfactants used in the present invention include polyoxyethylene glycol, polyoxypropylene glycol, polyoxypropylene triol,
Polyoxypropylene tetraol, condensates of ethylene oxide or propylene oxide and alkyl amines, condensates of ethylene oxide or propylene oxide and alkylamides, alkyls of ethylene glycol, propylene glycol, ethers and ester alcohols of polyethylene glycol and polypropylene glycol Etherified products with esters, derivatives of ethylene oxide and propylene oxide such as alkyl ethers and allyl ethers of ethylene glycol, propylene glycol, and polypropylene glycol, or alkyl allyl ethers and alkyl esters, glycols, glycerin, polyglycerin, pentaerythritol sorbitol, etc. Nonionic surfactants such as hydrohydric alcohols, fatty acid esters or naphthenic acid esters of polyhydric alcohols, low molecular weight polyvinyl alcohol with a molecular weight of 10,000 or less, partial esterification products of low molecular weight polyvinyl alcohol, saturated fatty acids of C4 or more and less than C10, and C10 or more. saturated and unsaturated fatty acids, metal salts of higher fatty acids such as metal salts of Li, Mg, Ca, Zn, Al, etc. of saturated and unsaturated fatty acids of C8 or higher, alkylbenzene sulfonates, alkylnaphthalene sulfonates, etc. Anionic surfactants such as alkylaryl sulfonates can be used. The amount of this surfactant used is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polypropylene resin. If the amount exceeds 10 parts by weight, the physical properties of the resulting polypropylene molded product may deteriorate and the surfactant may ooze out, which is undesirable. The method for producing a polypropylene molded article of the present invention includes:
Polypropylene resin, polar polymer, antistatic agent or surfactant, and if necessary coloring agent are premixed in a mixing machine such as a drum blender, V-type blender, ribbon blender, etc., and this is extruded into various types. The mixture is heat-kneaded and molded using a heat-kneading device such as a kneading machine, and then subjected to corona discharge treatment. Of course, the present invention does not exclude products that are laminated by a molding method such as coextrusion on a regular polypropylene molded product to which no polar polymer is added, and then subjected to corona discharge treatment. This corona discharge treatment may be carried out by a commonly used corona discharge treatment, preferably 35 to 55 dyne/
It is best to perform a corona discharge treatment of cm. The temperature of heating and kneading must be higher than the melting and softening temperature of the polypropylene resin and lower than the decomposition temperature, but in particular, the temperature must be higher than the melting temperature of the polar polymer, so that the polypropylene resin and the polar polymer are uniformly kneaded. It is necessary to do so. (Example) 100 parts by weight of ethylene-propylene block copolymer (manufactured by Chitsuso Petrochemical) with a melt index of 1.0 and 20% vinyl acetate content as a polar polymer.
5 parts by weight of ethylene-vinyl acetate copolymer (manufactured by Nippon Unicar) and 0.8 parts by weight of polyoxyethylene alkylamine as an antistatic agent were mixed in a drum blender for 30 minutes, and then melted and extruded in an extruder to obtain a thick texture. Each sheet is sheeted to 0.75mm and 300mm wide, and at the same time, a corona discharge treatment machine (Kasuga Denki) is used to
38dyne/cm (70V, 2.2A), 47dyne/cm (90V,
3.6A), 50dyne/cm (110V, 5A), 54dyne/cm
(130V, 6.4A) to obtain a polypropylene sheet-shaped molded product. The printability (printing unevenness and peeling test) using offset ink was measured for the obtained sheet-like molded product. The results are shown in Table 1. The printing unevenness and peeling tests were measured using Daikyure RT-7 (manufactured by Dainippon Ink and Chemicals Co., Ltd.) as an offset ink in the following manner. Printing unevenness test: Daikyure RT-7 was offset printed on the obtained sheet-like molded product using an RI tester. Ink coverage (printing unevenness) was evaluated based on the following criteria. Grade 5 A...The ink is 100% on the printing surface,
A state in which the color of the ink is dark (the amount of ink adhered is large). 5th class B...The ink is 100% on the printing surface,
A state in which the color of the ink is light (the amount of ink attached is small). Grade 4: A state in which 80 to 90% of the ink is on the printing surface. Grade 3: A state in which 50% of the ink is on the printing surface. Grade 2: A state in which 30% of the ink is on the printing surface. Grade 1: Ink is not on the printing surface at all (0
%) condition. Peeling test: Daikyure RT-7 was offset printed on the obtained sheet-shaped molded product, and this was heated at a temperature of 20°C.
After leaving it in an atmosphere of ℃ and 60% humidity for 2 days, make cuts with a razor so that 100 squares are formed at 1mm intervals on the printed surface, apply cellophane tape to this, and quickly peel it off to prevent it from peeling off. The number of squares remaining was evaluated according to the following criteria. 5th grade...100 squares remaining 4th grade...90-95 squares remaining 3rd grade...60-70 squares remaining 2nd grade...30-50 squares remaining Grade 1: No squares left.Furthermore, for items that fall under grade 5 according to the above evaluation criteria, use a razor to form 400 squares at 0.5mm intervals on the printed surface. A cut was made, and cellophane tape was removed in the same manner, observed, and re-evaluated using the following criteria. 5th grade A...400 squares remained 5th grade B...1 or more squares peeled off Example 2 Using the formulation of Example 1 instead of polyoxyethylene alkylamine as an antistatic agent The same measurements were carried out as in Example 1 except that 1.5 parts by weight of PEG-6000 (manufactured by Daiichi Kogyo Seiyaku) was added as a surfactant. The results are shown in Table 1. Example 3 The same measurements were carried out as in Example 1 except that ethylene-methyl ethyl methacrylate copolymer was used as the polar polymer and beef tallow ethylene-oxide adduct was used as the antistatic agent. The results are shown in Table 1. Example 4 The same measurements were carried out as in Example 1 except that chlorinated polyethylene was used as the polar polymer and N-N-bis(2-hydroxyethyl)stearylamide was used as the antistatic agent. The results are shown in Table 1. Example 5 The same measurements were carried out as in Example 2 except that chlorinated polyethylene was used as the polar polymer and stearin monoglyceride was used as the surfactant. The results are shown in Table 1. Example 6 The same measurements were carried out as in Example 1 except that ethylene-acrylic acid copolymer was used as the polar polymer and glycerin lanophosphate was used as the antistatic agent. The results are shown in Table 1. Example 7 The same measurements as in Example 2 were conducted except that ethylene-acrylic acid copolymer was used as the polar polymer and polyoxystearylamide was used as the surfactant. The results are shown in Table 1. Comparative Example 1 The same measurements as in Example 1 were carried out except that no antistatic agent was added (same as in Example 2 except that no surfactant was added). The results are shown in Table 1. Comparative Example 2 The same measurements as in Example 3 were performed except that no antistatic agent was added. The results are shown in Table 1. Comparative Example 3 The same measurements as in Example 4 were carried out except that no antistatic agent was added (same as in Example 5 except that no surfactant was added). The results are shown in Table 1. Comparative Example 4 The same measurements as in Example 6 were carried out except that no antistatic agent was added (same as in Example 7 except that no surfactant was added). The results are shown in Table 1.

[Table] (Effects) The polypropylene molded product of the present invention is formed by molding a composition obtained by adding a specific amount of polar polymer and a specific amount of antistatic agent or surfactant to a polypropylene resin and heating and kneading the mixture. Since the molded product is subjected to corona discharge treatment, it has better printability in offset printing and has better adhesion with printing ink compared to polypropylene resin with polar polymer added and corona discharge treatment. In good condition.

[Claims]

1. Antistatic foamed polyolefin sheet containing polyoxyethylene alkylamine as the main component, which is compatible with the above main component and contains non-volatile additives with a freezing point of 20°C or lower. agent. 2. The antistatic agent for foamed polyolefin sheets according to claim 1, wherein the additive has a boiling point of 150° C. or higher. 3. The antistatic agent for a foamed polyolefin sheet according to claim 1, wherein the additive is ethylene glycol. 4. The antistatic agent for a foamed polyolefin sheet according to claim 1, wherein the additive is tetraethylene glycol dimethyl ether. 5. The antistatic agent for the foamed polyolefin sheet according to claim 1 above, wherein the blending ratio of the main component and the additive is 5 to 40% of the additive to the entire antistatic agent. .