Thermoplastic moulding materials

Details Thermoplastic moulding materials Thermoplastic moulding materials

2001-06-18

2003-06-17

Mullis, Jeffrey (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...

C525S068000, C525S071000

Reexamination Certificate

active

06579937

ABSTRACT:

The present invention relates to thermoplastic molding compositions with improved processing properties, based on graft copolymers and on block copolymers.
Mixtures of impact-modified thermoplastic copolymers based on vinylaromatic polymers and graft rubbers are known to the skilled worker as ABS polymers or ASA polymers, and are commercially available. Blends of these ASA polymers or ABS polymers with other thermoplastics, in particular with polycarbonates, are also known.
The introduction of ever faster processing machinery means that products of this type are required to have, in particular, high flowability during injection molding and capability for demolding without breakage. In thermoforming a particularly important factor is high elongation at break.
In order to optimize these properties, use is generally made of various additives, but these often improve only one property while adversely affecting another desired property. For example, additives for improving flowability and thermoforming properties often lead to losses of mechanical properties, while additives for improving the moldability frequently impair flowability.
U.S. Pat. No. 5,760,134 discloses thermoplastic molding compositions made from
(A) a graft copolymer made from an elastomeric polyacrylate graft core with a graft shell,
(B) a thermoplastic polymer built up from styrene and/or &agr;-methylstyrene, and, where appropriate, acrylonitrile and, where appropriate, other monomers, and
(C) an elastomeric block copolymer built up from at least one block A formed from vinylaromatic monomer units and forming the hard phase and/or a block B formed from diene monomers and forming a first elastomeric (soft) phase, and at least one elastomeric block B/A formed from vinylaromatic monomers and also from diene monomers and forming a soft phase.
The proportion of 1,2-linkages in the polydiene within the block B/A of component C is not disclosed in U.S. Pat. No. 5,760,134.
It is an object of the present invention, therefore, to provide thermoplastic molding compositions based on ABS polymers or on ASA polymers and having a balanced property profile.
We have found that this object is achieved, in one first embodiment of the invention, by way of thermoplastic molding compositions comprising
(A) from 5 to 98% by weight, based on the total weight of the molding composition, of an elastomeric graft copolymer built up from
(a
1
) from 30 to 90% by weight, based on (A), of a graft base with a glass transition temperature (T
g
) below −10° C. made from
(a
11
) an at least partially crosslinked acrylate polymer formed from
(a
111
) from 50 to 99.9% by weight, based on (a
11
), of at least one C
1
-C
10
-alkyl acrylate,
(a
112
) from 0.1 to 5% by weight, based on (a
11
), of at least one polyfunctional crosslinking monomer and
(a
113
) from 0 to 49.9% by weight, based on (a
11
), of a further monomer which is copolymerizable with (a
111
) selected from the group consisting of the vinyl C
1
-C
8
-alkyl ethers, butadiene, isoprene, styrene, acrylonitrile and methacrylonitrile, and/or methyl methacrylate
and/or
(a
12
) a diene polymer built up from
(a
121
) from 60 to 100% by weight, based on (a
12
), of at least one diene and
(a
122
) from 0 to 40% by weight, based on (a
12
), of further copolymerizable monomers selected from the group consisting of the C
1
-C
10
-alkyl acrylates, vinyl C
1
-C
8
-alkyl ethers, butadiene, isoprene, styrene, acrylonitrile and methacrylonitrile, and/or methyl methacrylate,
(a
2
) from 10 to 70% by weight, based on (A), of a graft with a (T
g
)above 50° C., grafted onto the graft base and built up from
(a
21
) from 50 to 95% by weight, based on (a
2
), of at least one vinylaromatic monomer,
(a
22
) from 5 to 50% by weight, based on (a
2
), of at least one polar, copolymerizable comonomer selected from the group consisting of acrylonitrile, methacrylonitrile, C
1
-C
4
-alkyl (meth)acrylates, maleic anhydride and maleimides, and (meth)acrylamide, and/or vinyl C
1
-C
8
-alkyl ethers, or a mixture of these,
(B) from 1 to 90% by weight, based on the total weight of the molding composition, of a copolymer composed of
(b
1
) from 50 to 99% by weight, based on (B), of at least one vinylaromatic monomer and
(b
2
) from 1 to 50% by weight, based on (B), of monomers as described for (a
22
),
(C) from 1 to 70% by weight, based on (A), (B), (C) and, where appropriate, (D) and (E), of an elastomeric block copolymer composed of at least one block C
A
forming a hard phase and having copolymerized units of a vinylaromatic monomer, and
at least one elastomeric block C
(B/A)
forming a soft phase and having copolymerized units of a vinylaromatic monomer, and also of a diene,
where the glass transition temperature (T
g
) of the block C
A
is above 25° C. and that of the block C
(B/A)
is below 25° C., and
the selected phase-volume ratio of block C
A
to block C
(B/A)
is such that the proportion of the hard phase in the entire block copolymer is from 1 to 40% by volume and the proportion by weight of the diene in the entire block copolymer is less than 50% by weight,
where the proportion of 1,2-linkages in the polydiene, based on the total of 1,2- and 1,4-cis/trans linkages, is below 15%,
and
(D) from 0 to 300% by weight, based on the weight of components (A) to (C), of a polycarbonate,
(E) from 0 to 30% by weight, based on the total weight of the molding composition, of conventional additives and processing aids.
The thermoplastic molding compositions of the invention have better flowability than comparable molding compositions together with better demoldability and thermoformability and show no reduction in coatability and are largely free from constituents which vaporize or exude.
They are suitable for producing films, moldings (especially sheets) and fibers, with excellent capability for further processing by thermoforming, and also for producing injection moldings, especially for fast processing with short cycle times.
If (A) is a butadiene rubber they have excellent puncture resistance and markedly improved notch impact strength. If (A) is an acrylate rubber, very good impact strength is a particularly remarkable feature.
Many demanding applications require good processability, high flowability, good demoldability and good impact strength of the finished part with respect to initiated or non-initiated fracture, together with good multiaxial impact strength (implying that the impact strength of the molding is good in every direction, with no directional preference), without any substantial impairment of other properties, such as heat resistance, stiffness and flexural strength.
To improve flowability it is usual to add lubricants, often with a reduction in the rubber content. Products with a low rubber content flow better than products of the same type with high rubber content, which have good impact strength but poor flowability. Simultaneous improvement in impact strength and flowability cannot be obtained simply by changing the rubber content.
A further object of the present invention is therefore to provide thermoplastic molding compositions based on ABS polymers or on ASA polymers, in particular on ABS polymers, with better flowability and impact strength than those of conventional materials and moreover with better demoldability, together with paler intrinsic color.
We have found that this object is achieved by way of another embodiment of the present invention. This embodiment provides thermoplastic molding compositions comprising
(A) from 5 to 98.9% by weight, based on the total weight of the molding composition, of an elastomeric graft copolymer built up from
(a
1
) from 30 to 90% by weight, based on (A), of a graft base with a glass transition temperature (T
g
) below −10° C. made from
(a
11
) an at least partially crosslinked acrylate polymer formed from
(a
111
) from 50 to 99.9% by weight, based on (a
11
), of at least one C
1
-C
10
-alkyl acrylate,
(a
112
) from 0.1 to 5% by weight, based on (a
11
), of at least one polyfunctional crosslinking monomer and
(a
113
) from 0 to 49.9% by weight,

Affiliated with

Also associated with

Rating

Thermoplastic moulding materials does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Thermoplastic moulding materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermoplastic moulding materials will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3105541