Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-08-15
2004-04-13
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S089000, C526S227000, C526S232300, C526S317100, C526S318000, C526S318100, C526S318440, C526S319000, C526S329200, C526S352000, C526S352200
Reexamination Certificate
active
06720398
ABSTRACT:
The present invention relates to the use of trioxepan compounds, or substituted 1,2,4-trioxacycloheptanes, in the process to make acrylic (co)polymers, preferably high-solid acrylic resins, styrenic (co) polymers and/or ethylenic (co)polymers, preferably low-density polyethylene (LDPE).
High-solid acrylic resins are resins that are typically used in coating compositions. For environmental reasons, such coating compositions preferably release as little volatile matter as possible when used. In order to achieve this, resins that contain as little as possible of one or more solvents are needed. In order to be able to handle the coating compositions, particularly when they are to be sprayed, it is typically required that acrylic resin compositions with a low molecular weight be used, so that a low solution viscosity is obtained. In practice, this means that in said coating compositions often use is made of acrylic resins with a low molecular weight and a narrow molecular weight distribution. An example of processes wherein such specific high-solid coating resins are produced can be found in WO 96/27620. In this patent application it is disclosed to use specific cyclic ketone peroxides. Similarly, WO 00/08072 discloses the use of specific dialkyl compounds in order to obtain the high-solid acrylic resins. However, there is a need for further alternative processes. In these alternative processes, preferably use is made of a peroxide that does not need to be phlegmatised, so that the high amount of peroxide that is used does not introduce an undesired solvent, such as solvents that alter the boiling point of the polymerisation medium.
For the production of styrenic resins, styrene is typically (co)polymerised by means of a radically induced process. The radicals can be formed by means of a thermal process wherein it is believed that styrene first dimerises and subsequently forms radicals with a third monomer molecule. However, in order to increase the reactor output and to gain better control over the molecular weight of the polymer, often one or more peroxides are used as a source of free radicals. Typically, a peroxide is sought that generates a polymer with a high molecular weight, compared with polymers produced with other peroxides under similar conditions. Such peroxides can be used in greater amounts, which will increase the polymerisation rate with an attendant reduction of the molecular weight of the resin. Hence, the same polymer as before can be produced at an increased polymerisation rate, leading to an increased reactor space-time yield. For this reason, difunctional peroxides, peroxides with two peroxygen bonds in one molecule, or peroxides that cause controlled cross-linking are considered for use or being used in conventional styrene polymerisation processes. However, alternative polymerisation systems, preferably ones that allow the reactor space-time yield to be increased even further, are still desired. To avoid undesired contamination of the final resin, it is preferred that the alternative peroxides contain less than 25% by weight, more preferably, less than 20% by weight, even more preferably less than 10% by weight of a phlegmatiser, based on the weight of the final formulation. Depending on the situation, it may be most preferred to have a peroxide formulation that is essentially phlegmatizer free.
Similarly, there is a need for a peroxide-initiated process wherein ethylene (co)polymers are produced that have a reduced level of phlegmatiser and/or which makes use of highly efficient peroxides.
The present invention relates to alternative processes wherein a new specific type of peroxide is used. In these processes, it was found that the molecular weight of the resulting resin could be accurately controlled, that the polymer yield was very high, and that some processes led to a colourless product. More particularly, the present invention relates to a process wherein monomers are polymerised using at least one initiator selected from trioxepan compounds of formula I
with R
1-3
being independently selected from hydrogen and substituted or unsubstituted hydrocarbyl groups, while two of the groups R
1-3
may be linked to form a ring structure. Preferably, R
1-3
are independently selected from the group consisting of hydrogen and substituted or unsubstituted C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
aralkyl, and C
7
-C
20
alkaryl, which groups may include linear or branched alkyl moieties, while two of the groups R
1-3
may be connected to form a (substituted) cycloalkyl ring; the optional one or more substituents on each of R
1
-R
3
being selected from the group consisting of hydroxy, alkoxy, linear or branched alk(en)yl, aryloxy, halogen, carboxylic acid, ester, carboxy, nitrile, and amido. Preferably, R
1
and R
3
are selected from lower alkyl groups, such as methyl, ethyl, and isopropyl, methyl and ethyl being most preferred. R
2
is preferably selected from hydrogen, methyl, ethyl, iso-propyl, iso-butyl, tert-butyl, amyl, iso-amyl, cyclohexyl, phenyl, CH
3
C(O)CH
2
—, C
2
H
5
OC(O)CH
2
—, HOC(CH
3
)
2
CH
2
—, and
wherein R
4
is independently selected from any of the group of compounds given for R
1-3
. Another preferred product is
A first group of preferred processes according to the invention are the polymerisation processes to make high-solid acrylate resins. These processes are of the conventional type, for example in bulk, suspension, emulsion or solution, except that at least one peroxide as described above is used. Preferably, use is made of a solution polymerisation.
A second group of preferred polymerisation processes according to the invention are the styrene polymerisation processes wherein at least 40% by weight of the monomer is styrene. Such processes include the production of copolymers such as polystyrene acrylonitrile (SAN), and rubber-modified polymers such as methacrylate-butadiene-styrene (MBS) and high-impact polystyrene (HIPS) resins, as is known in the art. The processes can be carried out by mass, suspension, emulsion or solution polymerisation processes as known in the art. Within this second group of processes, mass polymerisation processes, also known as bulk polymerisation processes, and/or suspension/mass processes, wherein first part of the polymerisation is carried out in suspension after which the reaction mixture is transferred to a mass process, are most preferred. In these most preferred processes, typically general-purpose polystyrene (GPPS) and/or HIPS is produced.
A third preferred group of preferred polymerisation processes are the high-pressure polymerisation processes wherein ethylene is (co)polymerised at pressures ranging from 500 to 4,000 bara. In these processes, the unique properties of the peroxides according to the invention are expected to allow very efficient polymerisation reactions with an improved control over the molecular weight of the resulting polyethylene or ethylene copolymer.
Typically, the polymerisation temperature for all of these processes will range from ambient to 400° C., preferably from 40° to 350° C. It is also possible to conduct the polymerisation using a temperature profile, e.g., to perform the initial polymerisation below 100° C. and then elevate the temperature above 100° C. to complete the polymerisation. In solvent polymerisation processes, the polymerisation is often conducted at the reflux temperature of the solvent or mixture of solvents. These variations are all known to the man skilled in the art, who will have no difficulty in selecting the reaction conditions of choice, depending on the particular polymerisation process and the specific radical polymerisation initiator used. However, the trioxepans are pre-eminently suited for use in high-temperature polymerisation processes, particularly those where the temperature is higher than 140° C., more preferably higher than 165° C., where conventional peroxides are too reactive, resulting in poor yields.
Suitable (co)monomers for producing high-solid solvent based coating resins are olefinic or ethyl
Hogt Andreas H.
Meijer John
Akzo Nobel N.V.
Fennelly Richard P.
Zalukaeva Tatyana
LandOfFree
Use of trioxepans in the process to make high-solid acrylic,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Use of trioxepans in the process to make high-solid acrylic,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Use of trioxepans in the process to make high-solid acrylic,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3201103