Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2001-12-27
2003-12-23
Hightower, P. Hampton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S310000, C528S322000, C528S332000, C524S606000, C524S608000, C525S430000, C525S435000, C525S436000, C162S157600, C162S158000, C162S164100, C162S164600, C162S167000, C162S168200, C162S183000, C162S185000, C162S202000
Reexamination Certificate
active
06667384
ABSTRACT:
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF INVENTION
The present invention relates to polyamide pre-polymers, polyamide polymers, a process for producing polyamide pre-polymers and polyamide polymers, and the resins resulting from reacting a polyamide polymer with an epihalohydrin. The resins of the present invention may be used as wet strength resins and/or creping aids in the papermaking industry as well as surface additives for wool.
BACKGROUND OF THE INVENTION
In the paper industry, poly(aminoamides) made from adipate and diethylenetriamine (DETA) are commonly used as pre-polymers for the preparation of polyamide polymers, and ultimately, wet strength resins (e.g. H. H. Espy,
TAPPI J.,
78, 90 (1995)). Typically, to result in a resin, a polyamide polymer is treated with epichlorohydrin, which reacts with the secondary amine on the polyamide polymer backbone to form azetidinium, chlorohydrin, epoxide or other functionalities necessary for self-crosslinking and reacting with the pulp fiber. Despite the use of this polymer, other poly(aminoamides) with novel structures are still being sought.
U.S. Pat. No. 3,159,612 (Tsou et al. '612), U.S. Pat. No. 3,305,493 (Emmons), and British Patent 1,051,579 (Tsou et al. '579) describe the synthesis of alternative polyamide polymers; however, each teaches a process where different polymer structures and different molecular weights than those contemplated by the present invention are obtained. More particularly, Tsou et al. use a one-step reaction process, involving a diamine and an acrylic or methacrylic ester. Emmons describes a process having “two steps”, however both reactants (a diamine and an acrylic or methacrylic ester in a 1:1 molar ratio) are added all at once. Thus, except possibly with respect to the reaction temperature (in the case of acrylic ester), the “two steps” are actually identical and are therefore, in reality, only one step. In fact, Emmons indicates that the “two steps” may occur concurrently or simultaneously.
Several problems exist in the prior art that are addressed by the present invention. More specifically, the prior art processes generate polymers having random placement of monomer residues and have less flexibility in polyamide structure design and property optimization. Still further, the polymers made according to the prior art have low molecular weights, which results in sub-optimal levels of wet strength.
SUMMARY OF THE INVENTION
The present invention contemplates polyamide pre-polymers, polyamide polymers, a multi-step process for the synthesis of polyamide pre-polymers and polyamide polymers using acrylates and at least one monomer containing at least two primary amines (hereinafter referred to as “diamine”), and resins resulting from reacting a polyamide polymer of the present invention with an epihalohydrin.
The present invention relates to a process comprising the steps of: (a) the Michael addition of a first diamine to an acrylate, thereby forming a reaction mixture containing an amine-containing diester or diacid intermediate pre-polymer reaction product; and (b) carrying out aminolysis and polymerization using either of two methods, Method (b1) or Method (b2). Method (b1) comprises adding a second diamine to the reaction mixture and heating the reaction mixture to an elevated temperature for a period of time ranging from about 2 hours to about 8 hours. Method (b2) adds a second diamine to the reaction mixture and introduces an enzyme, acting as a catalyst, into the reaction mixture, which is then heated to an elevated temperature. Preferably, the enzyme introduced into Method (b2) in the polymerization reaction is a hydrolase enzyme, wherein about 0.1% to about 10% by weight of the enzyme, relative to the total weight of the monomers (diamine and acrylate), is used. The final reaction product resulting from a process of the present invention may be either a linear or a branched condensation polymer having a molecular weight ranging from about 1490 to about 200,000 daltons and a polydispersity (M
w
/M
n
) ranging from about 2.0 to about 10.0.
A method for making a polyamide resin comprising the steps of (i) reacting the final reaction product, a polyamide polymer, with an epihalohydrin, and (ii) allowing the reaction to proceed where the final reaction product is cross-linked with itself.
An object of the present invention is to synthesize and develop regio-regular polyamide structures that contain a high proportion of secondary amine groups to carbons on the polymer repeat units, and have a high molecular weight, as well as provide a process for the synthesis of those polyamide polymers, polyamide pre-polymers, and ultimately resins that were reacted with a halohydrin.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
The present invention contemplates polyamide pre-polymers, polyamide polymers, a multi-step process for the synthesis of polyamide polymers as well as polyamide pre-polymers using acrylates and at least one monomer containing at least two primary amines, and resins resulting from reacting a polyamide polymer of the present invention with an epihalohydrin.
There are several distinct advantages conferred by the present invention. First, the development of a multi-step process allows for the production of more general polyamide structures than is currently found in the art, thereby providing greater flexibility in structure design and property optimization such that there is a wider range of possible polymer structures. Second, the optional use of different diamines in steps (a) and (b) further provides for greater flexibility in polyamide structure design and property optimization. However, even when the same diamine is used in both reaction steps (a) and (b), the present invention differs from the prior art. For example, according to the prior art, when the diamine is NH
2
—C
n
H
2n
—(NH—C
n
H
2n
)
x
—NH
2
and R is a C2-C6 alkylene moiety, the polymer repeat unit is:
[NH—C
n
H
2n
—(NH—C
n
H
2n
)
x
—NH—CO—R—]
where 0≦x≦6, and 2≦n≦10. For easier visualization, W has been denoted as [NH—C
n
H
2n
—(NH—C
n
H
2n
)
x
—NH]. Thus the same repeat unit is:
[W—CO—R—]
However, when the process of the present invention utilizes the above-noted starting materials, a different polymer repeat sequence is obtained, for example:
[W—CO—R—W—R—CO]
A third advantage of the present invention is that typical polymers in the art are generated having a random placement of monomer residues, whereas the process of the present invention generates polyamide polymers having discrete and regio-regular polymer structures. These regio-regular and discrete polymers are advantageous because they allow structures to be designed with greater specificity, and therefore, increase the likelihood of greater numbers of the polymers having a particular functionality. The fourth advantage of the present invention is that the polyamide polymers synthesized according to typical methods known in the art (e.g., Emmons) have low molecular weights (about 300 to 1000 Daltons) whereas the polyamide polymers of the present invention have higher molecular weights (at least 1490 Daltons, but usually much higher), which provide improved wet strength.
Note that in comparison to conventional adipic acid-DETA polymers (e.g., Espy, 1995), the present invention provides polyamide polymers having at least one additional secondary amine per repeating unit when using the same diamine as the starting materials thereby enabling the polymer to react with an epihalohydrin and allowing for crosslinking of the polymer. The polyamide pre-polymers according to the present invention, such as those made using methyl acrylate and diethylene triamine (DETA) or dipropylene triamine (DPTA), have one secondary amine for about every 3-5 carbons, whereas in the backbone of a conventional adipate/DETA pre-polymer, synthesized by the polymerization of adipic acid and DETA, there is only 1 secondary amine for every 10 carbons on the polymer repeat units. The level of functionality on
Cheng Huai Nan
Gu Qu-Ming
Maslanka William W.
Michel Armin
Staib Ronald R.
Hampton Hightower P.
Hercules Incorporated
Rossi Joanne
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