Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-10-03
2002-02-26
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S319000, C526S328000, C526S328500, C526S329000, C526S329100, C526S329200, C526S332000, C526S335000, C526S336000, C526S337000, C526S340000, C526S347000, C526S348000
Reexamination Certificate
active
06350842
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to allylic copolymers. More particularly, the invention relates to allylic copolymers that have broad molecular weight distributions. The copolymers are particularly useful, for example, as toner resins.
BACKGROUND OF THE INVENTION
Allyl alcohol and allyl alcohol alkoxylates are useful, unique, hydroxyl functional monomers. They readily copolymerize with most commonly used monomers, e.g., vinyl aromatics, acrylates and methacrylates, vinyl ethers and esters, vinyl halides, conjugated dienes, and many others. These allylic monomers not only contribute hydroxyl functionality to the copolymers, but they also regulate the molecular weight of the copolymers and control the polymerization rate. When even a small portion of allylic monomer is used, a low molecular weight polymer is produced.
U.S. Pat. No. 5,382,642 teaches how to prepare copolymers of vinyl aromatics and allyl alcohol propoxylates. The copolymers have hydroxyl numbers of 80-260 mg KOH/g, and number average molecular weights from 500 to 3500. They are particularly useful for polyurethane, alkyd, and melamine coatings.
U.S. Pat. No. 5,451,652 teaches how to prepare homopolymers of allyl alcohol propoxylates, and copolymers of allyl alcohol and allyl alcohol propoxylates. These polymers are highly hydroxyl-functionalized, and are particularly useful as crosslinking agents.
U.S. Pat. No. 5,475,073 teaches how to prepare hydroxyl acrylic resins by substituting allyl alcohol and allyl alcohol propoxylates for hydroxyalkyl acrylates or methacrylates. By using the allylic monomers, low molecular weight resins are advantageously produced without the need for a chain transfer agent or solvent. The resins have hydroxyl numbers from 50 to 450 mg KOH/g, and number average molecular weights from 500 to 10,000. They are particularly useful for acrylicurethane and acrylic-melamine coatings.
U.S. Pat. No. 5,480,954 teaches how to prepare copolymers of allyl esters with allyl alcohol or allyl alcohol propoxylates. Compared with the polymers taught in U.S. Pat. No. 5,451,652, these copolymers have lower hydroxyl numbers, improved solubility in organic solvents, and better compatibility with other resins.
U.S. Pat. No. 5,646,225 teaches how to prepare water-soluble or water-dispersible resins. These resins are prepared by copolymerizing an allyl alcohol propoxylate, a vinyl aromatic monomer, and acrylic acid. They are particularly useful in water-borne coatings and inks.
The polymers disclosed in the above U.S. patents all have low molecular weights and narrow molecular weight distributions. They are highly valuable as hydroxyl functional resins in high-solids or low-VOC coatings because their low molecular weights and narrow molecular weight distributions give low solution viscosities.
Allylic copolymers having high molecular weights and broad molecular weight distributions are needed, for example, in toner resins. However, they are difficult to prepare.
Commonly used toner resins are high molecular weight copolymers of styrene and butadiene, or styrene and acrylates. Usually, they are prepared by suspension or emulsion polymerization. Toner resins usually require broad molecular weight distributions or bimodal distributions because the low molecular weight portion gives the toner low melt viscosity and good flexibility, while the high molecular weight portion improves anti-offset and anti-winding characteristics.
U.S. Pat. No. 5,219,947 teaches how to prepare a toner resin by a two-stage polymerization process. In the first stage, a low molecular weight polymer is formed in a solution polymerization. In the second stage, the low molecular weight polymer from the first stage is dissolved in a monomer, and the monomer is then polymerized by a suspension polymerization. The preparation is rather complicated not only because there are two different polymerization processes involved, but also because both the organic solvent from the first stage and water from the second stage must be removed from the product.
Copending application Ser. No. 09/085,039 teaches how to prepare high molecular weight, broad molecular weight distribution, allylic copolymers. These copolymers are particularly useful as toner resins. They are prepared by copolymerizing an ethylenic monomer, a monofunctional allyl monomer, and a multifunctional allyl monomer. No solvent is needed in the preparation. However, removing the unreacted multifunctional allyl monomer, such as diallyl phthalate, is found to be very difficult.
New methods for preparing allylic copolymers of high molecular weight and broad molecular weight distribution are needed. Ideally, the preparation does not require the use of a multifunctional allylic monomer.
SUMMARY OF THE INVENTION
The invention is a process for preparing an allylic copolymer that has a broad molecular weight distribution. The process comprises free radically copolymerizing a mixture of a mono-ethylenic monomer, a multi-ethylenic monomer, and a mono-allylic monomer to produce an allylic copolymer that has a high molecular weight, a broad molecular weight distribution, and a low gel content.
The invention includes an allylic copolymer that comprises about 0.1% by weight to about 10% by weight of multi-ethylenic monomeric units, about 5% by weight to about 40% by weight of mono-allylic monomeric units, and about 50% by weight to about 95% by weight of mono-ethylenic monomeric units. The polymer has a weight average molecular weight greater than about 10,000, a molecular weight distribution (Mw/Mn) greater than about 5, and a gel content less than about 10% by weight. It is particularly useful as a toner resin.
DETAILED DESCRIPTION OF THE INVENTION
The process of the invention comprises free radically copolymerizing a monomer mixture containing: a) a mono-ethylenic monomer; b) a multi-ethylenic monomer; and c) a mono-allylic monomer.
The mono-ethylenic monomer suitable for use in the invention has one free radically polymerizable group. Preferably, the group is —CR═CH
2
, wherein R is hydrogen, or C
1
to C
10
alkyl. Examples of suitable monoethylenic monomers are vinyl aromatics, vinyl halides, vinyl ethers, vinyl esters, unsaturated nitrites, acrylic and methacrylic acids and their esters, conjugated dienes, and the like, and mixtures thereof. Preferred monoethylenic monomers are vinyl aromatics, C
1
to C
10
alkyl acylates and methacrylates, and conjugated dienes. Particularly preferred are styrene, methyl methacrylate, butyl methacrylate, butyl acrylate, isoprene, and butadiene. More preferred are mixtures of styrene with butyl acrylate, and styrene with butadiene.
Usually, the mono-ethylenic monomer is the major component of the monomer mixture. The amount used is determined by many factors, particularly the desired glass transition temperature (T
g
) of the copolymer. For toner applications, the copolymer is required to have a T
g
greater than about 50° C. The T
g
of the copolymer is essentially determined by the monomeric type and comonomer ratio. For example, when a low T
g
mono-allylic monomer is used, a relatively large amount of a high T
g
mono-ethylenic monomer is required to achieve a high T
g
copolymer. The mono-ethylenic monomer is usually used in an amount greater than about 50% by weight of the copolymer composition.
The multi-ethylenic monomer suitable for use in the invention contains more than one free radically polymerizable ethylenic group as defined above. Examples are divinyl aromatics, diacrylates, and dimethacrylates. Preferred multi-ethylenic monomers are divinyl benzene (DVB), and ethylene glycol dimethacrylate.
The amount of multi-ethylenic monomer used is important because it determines the molecular weight of the copolymer. The multi-ethylenic monomer has two or more reactive carbon-carbon double bonds that participate in the polymerization. This results in polymeric chain branching and an increase in copolymer molecular weight. Using too much multi-ethylenic monomer causes gel formation during polymerization. Gel formation is undesirable because
Arco Chemical Technology, l.p.
Guo Shao
Pezzuto Helen L.
LandOfFree
Preparation of allylic copolymers of broad molecular weight... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Preparation of allylic copolymers of broad molecular weight..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of allylic copolymers of broad molecular weight... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2964905