Thermoplastic compound

Details Thermoplastic compound Thermoplastic compound

1999-03-04

2001-05-01

Nutter, Nathan M. (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...

C525S054200, C525S054300, C525S070000, C525S071000, C525S073000, C525S077000, C525S078000, C525S079000, C525S080000, C525S083000, C525S084000, C525S087000, C525S09200D, C525S09200D, C525S095000

Reexamination Certificate

active

06225404

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This is a national phase application of International Application No. PCT/SE97/00822, filed May 21, 1997.
The present invention relates to a new thermoplastic compound comprising at least one linear or branched thermoplastic polymer or copolymer compounded with at least one hyperbranched dendritic polyester macromolecule. The linear or branched thermoplastic polymer or copolymer is fitted with at least one reactive or graftable site (F
1
) and the hyperbranched dendritic macromolecule is through its terminal chain extender functions and/or through an optional chain termination and/or an optional functionalization fitted with at least one reactive or graftable site (F
2
), which reactive or graftable site (F
2
) is reactive to or graftable onto said reactive or graftable site (F
1
). In a further aspect, the invention relates to a thermoplastic composition comprising at least two components, whereby at least one is said thermoplastic compound. In yet a further aspect, the invention relates to a thermoplastic article made of one or more thermoplastic compounds or compositions, whereby at least one is said thermoplastic compound.
Adhesion and compatibility phenomena have during recent years become important issues in many scientific and technological areas including or comprising various polymer combinations, mixtures and blends. The question of improved adhesion and/or compatibility between for instance various thermoplastic polymers is pronounced in areas such as joints, surface coatings, sandwich structures, composite materials and polymer blends. Adhesion depends on a complex series of processes comprising complementary as well as contradictory theories including the theories of mechanical interlocking, molecular entanglement, electrostatic adhesion, interlocking, boundary layers, interfaces, adsorption and wetting, interdiffusion and chemical bonding. Enhanced compatibility of immiscible phases of liquid or solid products is known to be affected by the use of for instance tensides working according to the principles of stabilising the polar
on-polar interface. Tensides are characteristically molecules having both a polar and a non-polar part. A tenside will orient its polar part towards a product surface having a certain polarity, whereas the non-polar part will orient towards a product surface being non-polar or less polar. However, although conventional tensides to a certain extent in thermoplastic blends, composites, filled thermoplastics and the like, will enhance compatibility and adhesion, they have molecular weights being too low to give significant effects in regard of improved mechanical properties. All adhesion processes mentioned above should contribute in order to obtain an optimised adhesion. Low molecular tensides will only affect a few of said adhesion processes positively and can even counteract other adhesion processes. The overall effect is thus that low molecular tensides most likely will merely act as plasticisers with a detrimental effect on the overall performance of thermoplastics.
In order to satisfy an ever increasing demand for new and/or more advanced thermoplastics and thermoplastic systems, interest has focused on blends and combinations of different polymers as well as different polymers and fillers and/or reinforcing materials as an inexpensive way to combine properties of different materials and to obtain thermoplastics for new and specific applications. Many thermoplastic polymers are incompatible with each other and/or various property modifying materials, such as filling and reinforcing materials, resulting in blends and combinations having poor mechanical properties. Additives such as compatibilisers and modifiers to improve the adhesion and/or compatibility between for instance different incompatible or near incompatible thermoplastic polymers are frequently used. An additive should, to obtain good adhesion in thermoplastic blends, composites, filled thermoplastics and the like, be designed to give a positive contribution throughout all known adhesion processes. The net adhesion will then be expected to become very efficient. A compatibilising additive should, to adhere to a non-polar surface, ideally have a long polymer, such as a polyolefine, tail of significant molecular weight, which tail can be attracted to a non-polar thermoplastic surface and adhere through closeness in surface energy and through molecular entanglement and interdiffusion. A compatibilising agent should also, to be able to adhere to a polar surface, ideally be provided with as large a polar surface as possible having a large number of polar and reactive sites or functions, such as hydroxyl groups. Adhesion to a polar surface can thus occur through electrostatic attraction forming for instance strong hydrogen bonds, through covalent bonds between a large number of reactive sites and a polar substrate as well as through chemical reaction between reactive sites being reactive to each other. A compatibilising additive should, furthermore, have a molecular weight high enough to not negatively affect mechanical properties and at the same time have a viscosity low enough to provide a maximised diffusion rate to the polar
on-polar interfaces of thermoplastic blends, composites, filled thermoplastics or the like to be compatibilised.
Normally two main types of polymers/copolymers are used as compatibilisers and modifiers: (a) block copolymers consisting of blocks of the materials to be combined and (b) those creating chemical bonds between the materials to be combined. The second type has the advantage of being less process demanding than the first one. A further type of compounds claimed to be useful as compatibilisers are disclosed in WO 95/106081. The compounds are branched fractal porous polymers comprising rigid aromatic recurring units having electrophilic or nucleophilic reactive moieties on the exterior thereof or are star polymers comprising a polymeric core being said fractal polymers and linear nitrogen containing polymeric moieties grafted to the exterior thereof.
A compatibiliser or modifier must in order to work satisfactorily fulfil at least two conditions, namely to reduce the interfacial energy between materials to be combined and to provide a good bonding therebetween. Graft polymers/copolymers are often used as compatibilisers to create chemical bonds and can be exemplified by maleic anhydride grafted polyolefines, such as polypropylene, commercially used as compatibiliser between for instance the otherwise incompatible polyolefines and polyamides. Maleic anhydride grafted polyolefines have a small polar group and few reactive sites, which is typical for most of the presently known and commercially used compatibilisers. The polyolefine part of the maleic anhydride grafted polyolefine is compatible with a polyolefine and the maleic anhydride part can create bonds with the polyamide. Polyolefines, especially polypropylene, and polyamides will hereinafter be used as model species.
The structure of a maleic anhydride grafted polyolefine, having one end standing maleic anhydride grafted onto a polyolefine chain, can be illustrated by below simplified Formula (I)
wherein
denotes a polyolefine chain of for instance Formula (II)
(polypropylene), wherein n is the degree of polymerisation.
Polyamides and polyolefines are two important species of thermoplastics used for large volume applications. Among polyamides, Polyamide 6 is, due to its high stiffness and good heat and abrasion resistance, commonly used as an engineering plastic in for instance the automotive industry. Polyolefines have the advantages of high chemical resistance, low density and good mechanical properties in addition of being relatively inexpensive.
The properties of polyamides and polyolefines are normally complementary to each other and it is thus of considerable interest to combine these materials to produce thermoplastic compositions and composites for specific applications. A specific example where a combination of materials overcomes the deficien

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