Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-03-21
2003-07-01
Mullis, Jeffrey (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S064000, C525S065000, C525S066000, C525S069000, C525S070000, C525S072000, C525S080000, C525S242000, C525S285000, C525S326400
Reexamination Certificate
active
06586525
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a binder resin applicable to polyolefinic resins, for example, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, etc. In more detail, it relates to a primer, paint, ink and adhesive composition to be used for the purpose of protection or beautiful ornament of polyolefinic resin moldings, films, etc.
Because of high productivity and broad degree of freedom for design as well as many advantages of light weight, antirust, shock resistance, etc., in recent years, plastics are used very frequently as the materials for automotive parts, electrical parts, building materials, food packaging film, etc. Above all, because of low price and many excellent properties such as moldability, chemical resistance, heat resistance, water resistance and good electrical characteristics, polyolefinic resins are used in broad range as industrial materials and are one of the materials that the growth of demand is most expected in future.
Different from synthetic resins with polarity such as polyurethane resin, polyamide resin, acrylic resin, polyester resin, etc., however, polyolefinic resin is nonpolar and crystalline, leading to drawbacks of difficult paintability and adhesion.
For the painting and adhesion onto such hard-adherent polyolefinic resin, low-chlorinated polyolefin that has strong adherence onto polyolefinic resin has been used so far as a binder resin.
For example, in Japanese Unexamined Patent Publication Nos. Sho 57-36128 and Sho 59-166534Japanese Patent Publication No. Sho 63-36624, etc., low-chlorinated polypropylene or low-chlorinated propylene-&agr;-olefin copolymer with chlorine content of 5 to 50%, containing carboxylic acid and/or carboxylic anhydride, is proposed as a painting primer or coating binder resin onto polyolefinic moldings.
Moreover, a composition (Japanese Unexamined Patent Publication Nos. Hei 4-248845 and 5-25405) having modified copolymer obtainable by graft copolymerizing &agr;, &bgr;-unsaturated vinyl monomer containing hydroxyl group onto styrene.conjugated diene block copolymer, followed by further chlorination, as an essential component, a composition (Japanese Unexamined Patent Publication No. Hei 5-25405) having chlorinated product of graft modified product from styrene.isoprene block copolymer as an essential component, a composition (Japanese Unexamined Patent Publication Nos. Hei 5-112750 and Hei 5-112751) having chlorinated product of graft modified product from propylene-ethylene-&agr;-olefin random copolymer as an essential component, etc. are also proposed.
Although these compositions exhibit good adherence onto hard-adherent polyolefin, they are remarkably poor in the “gasohol resistance test” being a criterion of solvent resistance, that is, in a testing method wherein painted plate is soaked into a gasoline/alcohol mixed solution (gasohol) obtainable by adding 10% of lower alcohol such as methanol or ethanol to regular gasoline and whether the solvent resistance is good or bad is judged by a time until the painted film is peeled off.
Also, a method of crosslinking carboxyl group-containing chlorinated polyolefin with epoxy resin that can be seen in Japanese Patent Publication Nos. Sho 63-50381 and Hei 01-16414 and Japanese Unexamined Patent Publication No. Hei 8-100032, etc., is excellent in the socalled gasoline resistance to soak only in regular gasoline, but poor in the gasohol resistance property.
Further, such descriptions can be seen that a composition (Japanese Unexamined Patent Publication Nos. Hei 7-247381 and Hei 7-247382) having modified chlorinated polyolefin obtained by reacting carboxyl group-containing chlorinated polyolefin with low-molecular diol or low-molecular compound containing hydroxyl group and amino group as an essential component and a composition (Japanese Unexamined Patent Publication No. Hei 10-158447) obtained by mixing carboxyl group-containing chlorinated polyolefin with acrylic-modified chlorinated polyolefin that was modified with acrylic resin with glass transition point of higher than 60° C., etc. are excellent in the gasohol resistance, but it is difficult to say that both really satisfy the gasohol resistance.
The invention provides a primer composition with improved gasohol resistance and adherence usable for painting the moldings, sheets, etc. of polyolefinic resins.
SUMMARY OF THE INVENTION
The primer composition of the invention that solves the subject aforementioned is a binder resin for polyolefinic resins comprising carboxyl group-containing chlorinated polyolefin obtainable by graft copolymerizing at least one kind of unsaturated carboxylic monomer selected from carboxylic acid and/or carboxylic anhydride onto polyolefin (I) in amounts of 1 to 10 wt. % and then chlorinating to chlorine content of 10 to 30 wt. %, and having carboxyl group-containing chlorinated polyolefin (II), which contains only not more than 2% of a component with molecular weight of 2,000 or lower, being the low-molecular weight region of said carboxyl group-containing chlorinated polyolefin, and which has a value of Mw/Mn, being a ratio of weight average molecular weight (Mw) to number average molecular weight (Mn), of not more than 4, as a major binder resin.
DETAILED DESCRIPTION OF THE INVENTION
The polyolefin graft copolymerized with unsaturated carboxylic acid concerning the invention can be obtained by melting polyolefin under heat and, if need be, reducing viscosity or degrading it by thermal decomposition, and then by graft copolymerizing unsaturated carboxylic acid monomer of carboxylic acid and/or carboxylic anhydride in amounts of 1 to 10 wt. % batchwise or continuously in the presence of radical generator.
As the polyolefins (I), crystalline polypropylene, noncrystalline polypropylene, propylene-&agr;-olefin copolymer etc. can be used solely or by mixing two or more kinds, but, from the points of workability and adhesiveness of binder resin, a crystalline polypropylene with weight average molecular weight of 10,000 to 150,000, a propylene-&agr;-olefin copolymer with weight average molecular weight of 10,000 to 150,000 in which 70 to 97 mol % of propylene component is contained and number of carbon atoms is 2 or 4 to 6, a propylene-butene-ethylene terpolymer with weight average molecular weight of 10,000 to 150,000 in which 70 to 97 mol % of propylene component, 2 to 25 mol % of butene component and 2 to 25 mol % of ethylene component are contained, or the like can be used. In the case of propylene-&agr;-olefin copolymer, the &agr;-olefin unit is preferable to be at least one kind of &agr;-olefin with number of carbon atoms of 2 or 4 to 6 selected from, for example, ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 3-methyl-l-pentene and 1-hexene.
If the weight average molecular weight of raw material polyolefin (I) is under 10,000 or the propylene component is under 70 mol %, then the adherence to polyolefinic resin and the gasohol resistance become poor, and, if the weight average molecular weight exceeds 150,000, then the primer does not become fine particles when painting by air spray etc. to spoil the beautiful appearance of painted surface, which is unpreferable. Moreover, if the number of carbon atoms of &agr;-olefin of propylene-&agr;-olefin copolymer exceeds 6, then the adherence to polypropylene resin becomes poor. Furthermore, the propylene content of propylene-butene-ethylene copolymer being terpolymer is preferable to be 70 to 97 mol % as described above, the butene content is preferable to be 2 to 25 mol % and the ethylene content is preferable to be 2 to 25 mol %.
The unsaturated carboxylic acid monomers usable for introducing carboxyl group include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, intaconic acid, itaconic anhydride, aconitic acid, aconitic anhydride, etc. and the amount of graft copolymerization is preferable to be 1 to 10 wt. % to polyolefin. If under 1%, the gasohol resistance becomes poor and the adherence to upper paint also becomes poor. If over 10%,
Ueda Takaaki
Urata Keiji
Mullis Jeffrey
Nippon Paper Industries Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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