Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-03-20
2002-06-11
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C523S351000
Reexamination Certificate
active
06403691
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high-concentration talc masterbatch. More particularly, the invention relates to a masterbatch that, when blended with a polypropylene resin, is capable of providing a thermoplastic resin composition suitable for injection molding.
2. Description of the Related Art
Because of their excellent property balance and moldability, polypropylene-based composite materials containing an inorganic filler, e.g., talc, and/or an elastomer are extensively used in recent years as automotive parts such as, e.g., bumpers, instrument panels, door trims, and pillar trims and as industrial parts such as, e.g., parts for domestic electrical appliances. On the other hand, since these ingredients are generally compounded by resin manufactures before being supplied as a composite material to molding manufacturers, even slight modifications of mold designs necessitate a composite material of a new grade having a modified makeup. There has hence been a problem that this constitutes a serious obstacle to grade integration.
Techniques for overcoming these drawbacks have been proposed. For example, JP-A-63-165439 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) proposes a technique in which a high-concentration talc masterbatch, a pigment masterbatch, and a polypropylene resin are metered and premixed together before being molded. JP-A-9-25447 proposes a technique in which a high-concentration talc masterbatch serving also as a color masterbatch is used. However, in these references, there is no description concerning mechanical properties. Furthermore, these techniques have a drawback that the masterbatches, which employ a polypropylene resin as a matrix resin, are less effective in reducing the degree of shrinkage and, hence, need to be used in a large amount. Consequently, further improvements are presently desired.
SUMMARY OF THE INVENTION
An object of the invention is to provide a high-concentration talc masterbatch which efficiently reduces the degree of molding shrinkage and the degree of thermal shrinkage and brings about satisfactory properties merely when it is melt-kneaded together with a base material within an injection molding machine.
The present inventors made intensive studies in order to eliminate the problems described above. As a result, they have found that a high-concentration masterbatch which gives moldings having a satisfactory appearance, can efficiently control the degree of shrinkage, and is suitable for grade integration can be obtained by incorporating a specific amount of a talc ingredient having a specific particle diameter and a specific amount of a metal soap ingredient into an elastomer ingredient having specific flowability. The invention has been completed based on this finding.
The invention provides a high-concentration talc masterbatch obtained by kneading the following ingredients (A) to (C) together and granulating the mixture:
(A) an elastomer having a melt flow rate of from 0.5 to 150 g/10 min: 10 to 60 parts by weight,
(B) talc having an average particle diameter of from 1 to 15 &mgr;m: 40 to 90 parts by weight,
(C) a metal soap: 0.01 to 5 parts by weight per 100 parts by weight of the sum of (A) and (B).
The high-concentration talc masterbatch of the invention is preferably one wherein the metal soap is a compound represented by the formula
(
RCOO
)
n
X
wherein R is a hydrocarbon residue having 10 to 40 carbon atoms; X is a metal selected from Li, Na, K, Mg, Zn, Ca, Ba, and Al; and n is 1, 2, or 3.
Furthermore, the high-concentration talc masterbatch of the invention is preferably one wherein the coefficient of decrease in shrinkage degree (K) per part by weight of the masterbatch (MB) added per 100 parts by weight of a base material is {fraction (1/10,000)} or higher and the coefficient of change in flexural modulus (L) per part by weight of the masterbatch (MB) added per 100 parts by weight of the base material is −50 or higher, the coefficients K and L being respectively determined by the following equations:
K
=(decrease in shrinkage degree)/(MB addition amount, parts by weight)
L
=[(flexural modulus after MB addition)−(flexural modulus before MB addition)]/(MB addition amount, parts by weight).
DETAILED DESCRIPTION OF THE INVENTION
[I] Constituent Ingredients
1. Elastomer (Ingredient (A))
(1) Elastomer Ingredient
The elastomer ingredient for use in the high-concentration talc masterbatch of the invention is used for the purposes of efficiently reducing the degree of shrinkage and bringing about a satisfactory appearance while maintaining or improving impact resistance.
Examples of the elastomer ingredient for use in the invention include ethylene/&agr;-olefin copolymer rubbers such as ethylenepropylene copolymer rubbers, ethylene/1-butene copolymer rubbers, ethylene/1-hexene copolymer rubbers, and ethylene/1-octene copolymer rubbers; ethylene/&agr;-olefin/unconjugated diene copolymer rubbers such as ethylene/propylene/ethylidenenorbornene copolymer rubbers (EPDM); and hydrogenated block copolymer rubbers such as hydrogenated styrene/butadiene/styrene triblock copolymers (SEBS) and hydrogenated styrene/isoprene/styrene triblock copolymers (SEPS).
(2) Production of Elastomer Ingredient
These elastomers are produced, for example, by the following methods.
(i) Production of Ethylene/&agr;-Olefin Copolymer Rubber
An ethylene/&agr;-olefin copolymer rubber can be produced through polymerization using a Ziegler catalyst comprising, e.g., a titanium compound such as a titanium halide, and an organoaluminum/magnesium complex such as an alkylaluminum/magnesium complex or alkylalkoxyaluminum/magnesium complex, an alkylaluminum or alkylaluminum chloride as well as using the metallocene catalyst described in, e.g., International Publication WO 9104257. The polymerization can be conducted by production processes such as, e.g., the vapor-phase fluidized-bed method, solution method, and slurry method.
(ii) Production of Hydrogenated Block Copolymers (SEBS, SEPS)
These triblock copolymers can be produced by the general anionic living polymerization method. An SEBS can be produced by a process comprising successively polymerizing styrene, butadiene, and styrene to produce a triblock copolymer and then hydrogenating the copolymer or by a process comprising first producing a styrene/butadiene diblock copolymer, converting the copolymer into a triblock copolymer with a coupling agent, and then hydrogenating the triblock copolymer. An SEPS can be produced by using isoprene in place of the butadiene in either of these processes.
(3) Properties of Elastomer
The elastomer for use in the invention has a melt flow rate (MFR; 230° C., 2.16 kg load) of from 0.5 to 150 g/10 min, preferably from 0.7 to 100 g/10 min, more preferably from 0.7 to 80 g/10 min. In case where the MFR of the elastomer is lower than the lower limit, it gives insufficient flowability. On the other hand, MFR thereof exceeding the upper limit result in molded objects having a poor appearance.
(4) Proportion of Elastomer
The amount of the elastomer ingredient (A) according to the invention incorporated in the masterbatch of the invention should be from 10 to 60 parts by weight and is preferably from 20 to 50 parts by weight. In case where the incorporation amount thereof exceeds the upper limit, a composite material obtained by blending the masterbatch gives molded objects having a reduced flexural rigidity. In case where the incorporation amount thereof is smaller than the lower limit, a composite material obtained by blending the masterbatch gives molded objects which have a poor appearance due to poor dispersion.
2. Talc (Ingredient (B))
The talc, ingredient (B), for use in the high-concentration talc masterbatch of the invention is used for the purposes of efficiently reducing the degree of shrinkage and bringing about a satisfactory appearance while preventing flexural rigidity from decreasing.
(1) Properties of Talc
The talc contai
Banno Yoshihiro
Zanka Yukihito
Cain Edward J.
Japan Polychem Corporation
Lee Katarzyna W.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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