Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-01-13
1999-10-19
Mullis, Jeffrey C.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 84, 525227, 525230, 525238, 525310, C08L 5104, C08L 3312, C08L 2512
Patent
active
059690429
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to thermoplastic molding materials containing a mixture of polymerization of a mixture consisting of ester of acrylic acid and a mixture consisting of and monomer mixture consisting of of a monomer mixture in the presence of the core (C1), consisting of methacrylic or acrylic acid and from 25 to 60 nm, and monomer mixture consisting of methacrylic or acrylic acid and from 90 to 300 nm, and with the further proviso that the ratio of the average particle sizes (d.sub.50)-C to (d.sub.50)-D is kept in the range from 2:1 to 5:1, and based on the sum of the components A, B, C and D, the percentages by weight of A, B, C and D summing to 100 and the difference between the refractive index of the components C and D and that of the mixture of the components A, B and, if required, E being less than 0.005.
The present invention furthermore relates to a process for the preparation of the novel thermoplastic molding materials, their use and the moldings obtainable therefrom.
EP-A 62 223 describes highly glossy, transparent, impact-resistant, thermoplastic molding materials comprising a hard methyl methacrylate polymer, a hard styrene/acrylonitrile polymer and a soft graft copolymer of alkyl (meth)acrylate and, if required, styrene on a rubber. The molding materials contain core/shell particles having a particle size of less than 0.2 .mu.m for improving the impact strength.
However, the toughness/rigidity ratio of such thermoplastic molding materials is still insufficient for some applications, in particular in the cosmetics sector. For various molding materials in the cosmetics sector, it is in fact necessary to have a material which is resistant to stress cracking and which, in addition to high transparency, also possesses a balanced toughness/rigidity ratio.
One possible method for increasing the impact strength of thermoplastic polymers is to chemically agglomerate a graft copolymer used as a modifier with the aid of a latex comprising a copolymer of ethyl acrylate and methacrylic acid (EP-A 347 726). An increase in the average particle diameter from 90 nm to 200-600 nm is observed. The disadvantage of this chemical agglomeration is the broad particle size distribution of the agglomerated fraction, which may lead to opacity and to yellowing of the polymer after grafting of the partly agglomerated latex. In addition, it is very difficult exactly to establish the agglomerated fraction.
Furthermore, GB-A 2 156 365 discloses that the impact strength of thermoplastic polymers can be increased by agglomerating said polymers with the aid of metal salts. However, this may result in salt occlusions in the polymer, which adversely affect its transparency.
It is an object of the present invention to remedy the disadvantages described and to provide improved transparent molding materials which are resistant to stress cracking and have high impact strength and in addition good optical properties.
We have found that this object is achieved by the thermoplastic molding materials defined at the outset.
We have also found a process for their preparation, their use for the production of moldings, and moldings produced from the novel thermoplastic molding materials.
The novel thermoplastic molding materials contain polymer obtainable by polymerization of a mixture consisting of of methyl methacrylate and C.sub.1 -C.sub.8 -alkyl ester of acrylic acid, obtainable by polymerization of a mixture consisting of a vinylaromatic monomer and a vinyl cyanide and copolymer obtainable from obtainable by polymerization of a monomer mixture consisting of and vinylaromatic monomer and obtainable by polymerization of a monomer mixture in the presence of the core (C1), consisting of -C.sub.8 -alkyl ester of methacrylic or acrylic acid and vinylaromatic monomer, from 25 to 60 nm, in particular from 30 to 55 nm, particularly preferably from 35 to 55 nm, and (D) obtainable from obtainable by polymerization of a monomer mixture consisting of and vinylaromatic monomer and obtainable by polymerization of a monomer in the presenc
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Guntherberg Norbert
Tiefensee Kristin
BASF - Aktiengesellschaft
Mullis Jeffrey C.
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