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
1998-08-27
2001-05-29
Cooney, Jr., John 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...
C523S201000, C428S402240, C428S403000, C525S179000, C525S183000, C525S902000
Reexamination Certificate
active
06239216
ABSTRACT:
The invention relates to multiphase thermoplastic resin compositions and more particularly to compositions in the form of a matrix in which nodules are dispersed.
Many thermoplastics have to be modified by incorporating rubbers or other polymers, for example in order to modify the flexural modulus thereof or to improve the impact strength.
The Applicant has discovered that if a third polymer (K) meeting certain criteria were to be added to a matrix (M) containing nodules (S), then a composition was obtained which had a new distribution of nodule sizes and for most of the nodules a reduction in size.
This has many advantages, for example when the polymer of the matrix is transparent or even translucent, the reduction in the size of the nodules increases the transparency or makes the polymer more translucent for a constant level of dispersed phase. The mechanical properties, such as tensile strength or impact strength, are also improved.
U.S. Pat. No. 5,070,145 describes compositions consisting of 80 parts of nylon-6 (PA-6) or nylon-6,6 (PA-6,6) in which 20 parts of a mixture (i) of a copolymer of ethylene and of an ethyl or butyl acrylate and (ii) of a copolymer of ethylene, ethyl acrylate and maleic anhydride have been dispersed. These compositions have good impact strength.
EP 284,379 describes multiphase compositions consisting of a polyamide and of an ethylene copolymer in the form of a polyamide matrix in which nodules (1) of an ethylene-ethyl acrylate-maleic anhydride copolymer are dispersed, and dispersed in these nodules (1) are nodules of polyamides. These nodules (1) are firstly prepared by dispersing a polyamide in the ethylene copolymer, and then these nodules are crosslinked and then dispersed in a polyamide. These compositions are also presented as having a good impact strength.
Patent FR 2,719,849 describes thermoplastic compositions consisting of a matrix of a thermoplastic polymer in which nodules of a second thermoplastic polymer, partially or totally encapsulated by an ethylene copolymer, are dispersed. These compositions are prepared by firstly encapsulating the second polymer and then the other polymer forming the matrix is added under conditions such that the capsules are not destroyed. This preparation is carried out in two steps which are completely separate or with one step following the other in the same extruder. These compositions have both good flexibility and good impact strength. The examples show PA-6, PA-12 or PBT (polybutylene terephthalate) matrices in which are dispersed nodules of PA-6,6 encapsulated by an ethylene-ethyl acrylate-glycidyl methacrylate copolymer. A comparative example shows that in a PA-6 matrix the PA-6,6 nodules encapsulated by the ethylene copolymer are coarser than the nodules formed only from the ethylene copolymer.
The present invention is therefore a thermoplastic composition comprising at least one polymer (M) forming a matrix in which are dispersed nodules of (K), nodules of (K) entirely or partly encapsulated in at least one polymer (S) and nodules of (S) and such that the nodules of (K) entirely or partly encapsulated in (S) are smaller than the nodules of (S).
The polymer (M) may be a mixture of several miscible polymers forming a homogeneous phase. The same applies to the polymer (K) and the polymer (S). The compositions of the invention may also comprise several types of encapsulated nodules, for example nodules of (K1) which are encapsulated in (S) and nodules of (K2) which are encapsulated in (S) or else nodules of (K1) which are encapsulated in (S1) and nodules of (K2) which are encapsulated in (S2).
The compositions of the invention are particularly useful for transparent polymers (M) which can be used, for example, to make packaging, pipes of which the contents must be visible, tanks in which the level must be visible, or protective films.
In order to modify the impact properties or the flexural modulus of a polymer (M), it is necessary to add a plasticizer and/or a polymer (S) to it. The drawback of a plasticizer is that, above a certain amount, it exudes and therefore the properties are not preserved. If the amount of (S) is increased too much, there may be compatibility problems and another property may also be affected. For example, if the amount of (S) in (M) is increased, a reduction in the flexural modulus is indeed obtained, but there is a reduction in the tensile strength, which may also be expressed by a decrease in the burst strength of an extruded tube.
For a transparent polymer (M), the increase in the amount of (S), for example in order to decrease the flexural modulus, may also, depending on the nature of (S), a decrease in the transparency.
The Applicant has therefore discovered that by adding a polymer (K) to a mixture of (S) in (M), nodules of (K), nodules of (K) entirely or partly encapsulated in (S) and nodules of (S), called the dispersed phase in (M), were obtained.
The majority (by weight) of this dispersed phase consists of nodules of (K) entirely or partly encapsulated in (S). This is the more so if matrices (M) containing an essentially equal amount of dispersed phase, that is to say that part of (S) dispersed in (M) has been replaced by (K), are compared.
Although nodules of (S) remain in the (M)+(S)+(K) mixtures, the number of them is not sufficient to impair the transparency, most of the nodules being nodules of (K) entirely or partly encapsulated in (S) and therefore having a smaller size than the nodules of (S) in (M), the transparency of (M)+(S)+(K) is superior to the transparency of (M)+(S) at the very least for a constant proportion of (M).
The present invention also relates to transparent thermoplastic compositions comprising at least one polymer (M) forming a matrix in which are dispersed at least one polymer (S) and at least one polymer (K) and such that their transparency is superior to that of compositions comprising only (M) and (S), the proportion of (M) being essentially the same.
Since effectively what is involved is a comparison of polymers (M) essentially containing the same amount of dispersed phase, matrices (M) containing either (S) or (S)+(K) are therefore compared, the amounts of (S) and (S)+(K) being essentially the same.
The transparency may be measured by the transmission of radiation of 560 nm through a film of 2 mm thickness and by the opacity.
Thus, for example, it has been discovered that the nodules of an ethylene/alkyl acrylate/maleic anhydride copolymer in a nylon-11 (PA-11) matrix have a size of 0.2 &mgr;m while, in the same matrix, the nodules of nylon-12 (PA-12) which are encapsulated in the same ethylene/alkyl acrylate/maleic anhydride copolymer have a size of 0.07 &mgr;m (this is the size Dv (volume diameter) of the nodule together with the capsule, i.e. approximately the external diameter of the capsule).
The present invention also relates to a thermoplastic composition comprising at least one polymer (M) forming a matrix in which are dispersed at least one polymer (S) and at least one polymer (K) and such that its flexural modulus is less than the expected flexural modulus, this expected modulus being calculated from the modulus of a composition comprising only a matrix (M) and the same amount of dispersed (S), and the modulus being calculated by adding the moduli of (M) and (K) in proportion to their proportions by weight.
For the PA-12+15% (S) example (Ex. 25), the modulus is 880. The expected modulus of PA-12+15% (S)+15% PA-11 is 860 (PA-11 has a modulus of 1000 compared with 1100 for PA-12), while the measured modulus is 740.
The compositions of the invention have many advantages:
they are more stable, the morphology of the majority of the dispersed phase being finer, that is to say that (M) and (S) have been made more compatible;
they are essentially as flexible as the compositions of (M) comprising nodules containing only (S) since the polymer (K) may be screened with a sufficient thickness of capsule (S). We will return to this point later in the text;
the finer morphologies also incr
Guibouin Chrystelle
Hert Marius
Montanari Thibaut
Perret Patrice
Thomasset Jacques
Atofina
Cooney Jr. John M.
Pennie & Edmonds LLP
LandOfFree
Thermoplastics with improved flexibility and transparency does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermoplastics with improved flexibility and transparency, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermoplastics with improved flexibility and transparency will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2535316