Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Silicon dioxide – silicic acid – orthosilicate – or...
Reexamination Certificate
2000-08-10
2001-09-25
Medley, Margaret (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Silicon dioxide, silicic acid, orthosilicate, or...
C508S551000, C106S482000, C106S485000, C106S486000, C106S491000, C524S232000, C524S231000, C523S210000, C523S001000
Reexamination Certificate
active
06294505
ABSTRACT:
The invention relates to an integrated additive composition, to processes for its preparation and to its use, in particular to its use in polyolefin films as in the production of polyolefin films and in injection moulding.
In the production of polymer films, in particular on the basis of polyolefins, two additives in particular among others play an important role: a) anti-blocking agents and b) slip agents. Synthetic amorphous, porous silica gels such as for example SYLOBLOC®, which is produced by the applicant GRACE GmbH itself, are widely used as anti-blocking agents. Aliphatic acid amides, in particular oleic acid amide and erucic acid amide, are often used as slip agents. These two components are typically used in concentrations of 1000 to 3000 ppm, relative to the component in question, in the polymer films.
In order to achieve profitable process conditions, it is of importance that pre-mixed powders comprising for example anti-blocking agent and slip agent are available. However, these pre-mixtures are frequently subject to a demixing process if the powdery material is pneumatically conveyed over longer distances. Furthermore, the organic components, such as for example slip agents, act as adhesives in such pre-mixed powders and have an adverse effect on the free-flowing properties of these powders.
Thus DE 12 64 054 Rexall Drug & Chemical Co. describes a powdery free-flowing additive composition which contains polyolefin powder, anti-blocking agents and slip aids. However, because of the different particle sizes and densities used, a separation of the individual components of the composition readily occurs.
EP-A-0 138 203 describes the preparation of mixtures of silica gel and slip agents in order to obtain polyolefin masterbatches with a high concentration of anti-blocking agent and slip agent. The first stage in the preparation of a masterbatch having a high concentration is the mixing of the silica gel with the slip agent. This is achieved, as described in example 1 of EP-A-0 138 203, by mixing in a double-cone mixer. Also, the additive described there is ground in an impact mill with the addition of liquid nitrogen. This disclosed process does not, however, lead to free-flowing powders which can be pneumatically conveyed without sticking or being separated into their constituents.
The object of the present invention is therefore to create a composition which combines several substances used as additives in the production of polymer films and is present in a form which allows it to be used in an economically advantageous way as a powder with good free-flowing properties. It is also the object of the invention to provide processes for the preparation of such compositions.
This object is achieved by an integrated additive composition which contains anti-blocking agents and at least one organic component which is characterized in that the organic component(s) is (are) localized in a concentration of 5 to 65 wt.-%, relative to the total weight of the composition, in the pores of the anti-blocking agent, the volume of the organic component(s) not being greater however than the pore volume of the anti-blocking agent.
The subject-matter of the present invention are also processes for the preparation of the integrated additive composition according to the invention.
The use of the compositions according to the invention in polyolefins and in injection moulding are also the subject-matter of the present invention.
Preferred versions of the invention are the subject-matter of the dependent claims.
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Luers Georg
Schmidt Andreas
Cross Charles A.
Medley Margaret
W. R. Grace & Co.,-Conn.
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