Patent Application
20140243477
The present invention relates to the use of copolymers (C) comprising at least one epoxy group and at least one alkoxysilane group as stabilizers for polymers (P). The invention further relates to processes for stabilizing polymers with respect to hydrolysis via addition of copolymers (C). The invention further relates to selected copolymers (C′) and mixtures comprising copolymers (C′).
Other embodiments of the present invention can be found in the claims, the description, and the examples. The abovementioned features of the subject matter of the invention, and the features thereof which will be explained hereinafter, can of course be used not only in the specific combination stated but also in other combinations, without exceeding the scope of the invention. Preferred and very preferred embodiments of the present invention in particular include those in which all of the features of the subject matter of the invention have the preferred and, respectively, very preferred meanings.
Polymers having hydrocarbon chains and alkoxysilane groups can crosslink and are therefore frequently used as starting materials for adhesive masses or for sealants, or for compositions for surface modification.
There are various known production processes for polymers having hydrocarbon chains and siloxane groups: U.S. Pat. No. 6,177,519 B1 describes the grafting of a polyolefin with a vinylsiloxane; U.S. Pat. No. 6,194,597 B1 moreover discloses the copolymerization of isobutene with silylstyrene or silylmethylstyrene.
WO 2012/032005 A1 describes terpolymers obtainable via copolymerization of electron-deficient olefins, of olefins which, at their olefinic double bond, bear only hydrogen atoms and/or carbon atoms, without electron-withdrawing substituents, and of alkoxyvinylsilanes, and also describes downstream products obtainable via modification or crosslinking of these terpolymers.
U.S. Pat. No. 5,354,802 describes resin compositions for blow molding comprising from 0.2 to 10 parts by weight of a styrene copolymer comprising from 40 to 97% by weight of styrene, from 60 to 3% by weight of a glycidyl ester of an alpha, beta-unsaturated acid, and from 0 to 50% by weight of other vinylic monomers.
U.S. Pat. No. 6,984,694 B2 describes the use of copolymers comprising epoxy-functionalized (meth)acrylic acid monomers, styrene and/or (meth)acrylic acid monomers, as chain extenders.
U.S. Pat. No. 4,393,156 and U.S. Pat. No. 4,393,158 describe the use of epoxysilanes and of certain epoxysiloxanes for stabilizing polyester carbonates or aromatic polycarbonates with respect to hydrolysis. However, the epoxysiloxanes described in that document do not involve copolymers comprising epoxy groups and alkoxysilane groups.
The unpublished PCT/EP2012/072489 describes mixtures comprising polyfunctional chain extenders and mono- or difunctional hydrolysis stabilizers for polymers.
Carbodiimides are often used industrially to stabilize polymers with respect to hydrolysis, an example being Stabaxol I, from Rhein Chemie. Monomeric carbodiimides are also known by way of example from U.S. Pat. No. 5,439,952 as hydrolysis stabilizers. However, their use often produces toxic byproducts, for example phenyl isocyanates.
Polymers, for example polycondensation polymers such as polyesters, are often susceptible to hydrolytic degradation at elevated temperatures. Conditions of this type occur by way of example when the polymers are processed with introduction of heat while moisture is simultaneously present. Hydrolysis of the polymers leads to molecular-weight reduction and to reduced melt viscosity, with simultaneous impairment of the mechanical properties of the polymers. These effects greatly restrict the usefulness of these hydrolysable polymers, and moreover result in high costs for drying before the polymers are processed.
It was therefore an object of the present invention to provide stabilizers which can be used for polymers and which reduce degradation and reduce the extent of hydrolysis. A particular object of the invention was to suppress reduction of the melt viscosity of polymers during processing. Another object of the present invention was to provide hydrolysis stabilizers which do not exhibit toxic byproducts.
Said objects have been achieved via the use of copolymers (C) comprising at least one epoxy group and at least one alkoxysilane group, as stabilizers for polymers (P), preferably comprising at least two epoxy groups and two alkoxysilane groups. It is preferable that the copolymers (C) are used as hydrolysis stabilizers or acid scavengers.
For the process of the present invention, alkoxysilane groups are groups of the general formula (I):
*—Si(OR1)n(R2)3-n (I)
where
For the purposes of the present invention, epoxy groups are groups of the general formula (II):
where
For the purposes of this invention, expressions of the type Ca-Cb indicate chemical compounds or substituents with a certain number of carbon atoms. The number of carbon atoms can be selected from the entire range from a to b, inclusive of a and b, a is at least 1, and b is always greater than a. Expressions of the type Ca-Cb-V are used for further specification of the chemical compounds or of the substituents. V here represents a class of chemical compound or class of chemical substituent, for example alkyl compounds or alkyl substituents.
The collective expressions used for the various substituents have the following detailed meanings:
C1-C20-alkyl: straight-chain or branched hydrocarbon moieties having up to 20 carbon atoms, for example C1-C10-alkyl or C11-C20-alkyl, preferably C1-C10-alkyl, for example C1-C3-alkyl, such as methyl, ethyl, propyl, isopropyl, or C4-C6-alkyl, n-butyl, sec-butyl, tert-butyl, 1,1-dimethylethyl, pentyl, 2-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 2-methylpentyl, 3-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, or C7-C10-alkyl, such as heptyl, octyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, 1,1,3,3-tetramethylbutyl, nonyl or decyl, or else isomers of these.
C2-C20-alkenyl: unsaturated, straight-chain or branched hydrocarbon moieties having from 2 to 20 carbon atoms and having a double bond in any desired position, for example C2-C10-alkenyl or C11-C20-alkenyl, preferably C2-C10-alkenyl, e.g. as C2-C4-alkenyl, such as ethenyl, 1-propenyl, 2-propenyl, 1-methylethenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, 2-methyl-1-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl, or C5-C6-alkenyl, such as 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-methyl-1-butenyl, 2-methyl-1-butenyl, 3-methyl-1-butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 1-methyl-3-butenyl, 2-methyl-3-butenyl, 3-methyl-3-butenyl, 1,1-dimethyl-2-propenyl, 1,2-dimethyl-l-propenyl, 1,2-dimethyl-2-propenyl, 1-ethyl-1-propenyl, 1-ethyl-2-propenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 1-methyl-1 -pentenyl, 2-methyl-1 -pentenyl, 3-methyl-1-pentenyl, 4-methyl-1-pentenyl, 1-methyl-2-pentenyl, 2-methyl-2-pentenyl, 3-methyl-2-pentenyl, 4-methyl-2-pentenyl, 1-methyl-3-pentenyl, 2-methyl-3-pentenyl, 3-methyl-3-pentenyl, 4-methyl-3-pentenyl, 1-methyl-4-pentenyl, 2-methyl-4-pentenyl, 3-methyl-4-pentenyl, 4-methyl-4-pentenyl, 1,1-dimethyl-2-butenyl, 1,1-dimethyl-3-butenyl, 1,2-dimethyl-1-butenyl, 1,2-dimethyl-2-butenyl, 1,2-dimethyl-3-butenyl, 1,3-dimethyl-1-butenyl, 1,3-dimethyl-2-butenyl, 1,3-dimethyl-3-butenyl, 2,2-dimethyl-3-butenyl, 2,3-dimethyl-1-butenyl, 2,3-dimethyl-2-butenyl, 2,3-dimethyl-3-butenyl, 3,3-dimethyl-1-butenyl, 3,3-dimethyl-2-butenyl, 1-ethyl-1-butenyl, 1-ethyl-2-butenyl, 1-ethyl-3-butenyl, 2-ethyl-1-butenyl, 2-ethyl-2-butenyl, 2-ethyl-3-butenyl, 1,1,2-trimethyl-2-propenyl, 1-ethyl-1-methyl-2-propenyl, 1-ethyl-2-methyl-1-propenyl or 1-ethyl-2-methyl-2-propenyl, or else C7-C10-alkenyl, such as the isomers of heptenyl, octenyl, nonenyl or decenyl.
C2-C20-alkynyl: straight-chain or branched hydrocarbon groups having from 2 to 20 carbon atoms and having a triple bond in any desired position, for example C2-C10-alkynyl or C11-C20-alkynyl, preferably C2-C10-alkynyl, e.g. C2-C4-alkynyl, such as ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methyl-2-propynyl, or C5-C7-alkynyl, such as 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 1-methyl-2-butynyl, 1-methyl-3-butynyl, 2-methyl-3-butynyl, 3-methyl-1-butynyl, 1,1-dimethyl-2-propynyl, 1-ethyl-2-propynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl, 1-methyl-2-pentynyl, 1-methyl-3-pentynyl, 1-methyl-4-pentynyl, 2-methyl-3-pentynyl, 2-methyl-4-pentynyl, 3-methyl-1-pentynyl, 3-methyl-4-pentynyl, 4-methyl-1-pentynyl, 4-methyl-2-pentynyl, 1,1-dimethyl-2-butynyl, 1,1-dimethyl-3-butynyl, 1,2-dimethyl-3-butynyl, 2,2-dimethyl-3-butynyl, 3,3-dimethyl-1 -butynyl, 1-ethyl-2-butynyl, 1-ethyl-3-butynyl, 2-ethyl-3-butynyl, or 1-ethyl-1-methyl-2-propynyl, or else C7-C10-alkynyl, such as the isomers of heptynyl, octynyl, nonynyl, decynyl.
C3-C15-cycloalkyl: monocyclic, saturated hydrocarbon groups having from 3 to 15 carbon ring members, preferably C3-C8-cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl, or else a saturated or unsaturated cyclic system, e.g. norbornyl or norbenyl.
Aryl: a mono- to trinuclear aromatic ring system comprising from 6 to 14 carbon ring members, e.g. phenyl, naphthyl, or anthracenyl, preferably a mono- to binuclear aromatic ring system, particularly preferably a mononuclear aromatic ring system.
For the purposes of the present invention, the symbol “*” in all chemical compounds characterizes the valency by way of which a chemical group has linkage to another chemical group.
In one preferred embodiment of the claimed use, the copolymers (C) are obtained via polymerization of monomers, where said monomers comprise those which
These monomers preferably correspond to the general formulae (III) and (IV):
where
It is preferable that at least 10%, particularly at least 20%, very particularly at least 30%, in particular at least 40%, of the monomers of the copolymers (C) comprise epoxy groups.
It is further preferable that at least 10%, particularly at least 20%, very particularly at least 30%, in particular at least 40%, of the monomers of the copolymers (C) comprise alkoxysilane groups.
In one preferred embodiment of the claimed use, the monomers of the copolymers (C) are selected from glycidyl acrylate, glycidyl methacrylate, styrene, vinyltriethoxysilanes, methacryloxypropyltrimethoxysilane, methacryloxypropyltris(2-propoxy)silane, methyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-propylhexyl acrylates, and alpha-methylstyrene. Preference is given to glycidyl methacrylate, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, styrene, and methyl methacrylate.
In another preferred embodiment of the claimed use, precisely two, three, or four monomers are selected of which the copolymers (C) are composed. In this case, there are no other monomers then present in the copolymer (C).
It is preferable that the precisely two monomers involve glycidyl methacrylate and vinyltriethoxysilane. In particular here, glycidyl methacrylate and vinyltriethoxysilane are used in a molar ratio in the range from 10:90 to 90:10, preferably from 20:80 to 80:20, particularly preferably from 30:70 to 70:30, very particularly preferably from 40:60 to 60:40.
It is further preferable that the precisely two monomers involve glycidyl methacrylate and methacryloxypropyltrimethoxysilane. In particular here, glycidyl methacrylate and methacryloxypropyltrimethoxysilane are used in a molar ratio in the range from 10:90 to 90:10, preferably from 20:80 to 80:20, particularly preferably from 30:70 to 70:30, very particularly preferably from 40:60 to 60:40.
It is further preferable that the precisely four monomers involve glycidyl acrylate, styrene, methyl methacrylate and methacryloxypropyltrimethoxysilane. In particular here, glycidyl acrylate and methacryloxypropyltrimethoxysilanes are used in a molar ratio in the range from 0.01 to 10.
The weight-average molar mass Mw of the copolymers (C) is preferably in the range from 100 to 50 000 g/mol, preferably from 2400 to 20 000, particularly preferably from 3500 to 13 000.
The copolymers (C) are produced by processes known to the person skilled in the art from the prior art, for example those described in WO 2012/098063 A1 or WO 2012/044981 A2.
In one preferred embodiment of the claimed use, the polymers (P) are polycondensates or polyadducts. It is preferable that the polymers (P) here are selected from the group of the polyesters, polyamides, polyurethanes, polycarbonates, and copolymers of these. In particular, the polymers (P) are selected from polyethylene terephthalates (PET), polybutylene terephthalates (PBT), polyethylene naphthalate (PEN), polycarbonate (PC), acrylonitrile-butadiene-styrene copolymer (ABS), biodegradable aliphatic-aromatic copolyesters, biopolymers, and nylon-6 (PA6).
The invention also provides a process for stabilizing polymers (P) with respect to hydrolysis, which comprises adding, to the polymers (P), an effective amount of copolymers (C). It is preferable that the amount of the copolymers (C) added is from 0.01 to 10% by weight, based on the total amount of polymer (P) and copolymer (C).
The addition of the copolymers (C) to the polymers (P) is achieved via processes known to the person skilled in the art from the prior art. In particular, the addition is achieved via extrusion or compounding.
The invention also provides copolymers (C′) composed of
It is preferable that copolymers (C′) are composed of
It is further preferable that copolymers (C′) are composed of
The copolymers (C′) are produced by the processes described above for the copolymers (C).
The invention also provides mixtures comprising copolymers (C′) and polymers (P), where the polymers (P) are preferably polycondensates or polyadducts. It is preferable that the amount of the copolymers (C) comprised in the mixtures is from 0.01 to 10% by weight.
It is further preferable that the polymers (P) here are selected from the group of the polyesters, polyamides, polyurethanes, polycarbonates, and copolymers of these.
It is likewise preferable that the polymers (P) here are PET, PBT, PEN, PC, ABS, biodegradable aliphatic-aromatic copolyesters, biopolymers, or PA6.
The mixtures are produced via processes known to the person skilled in the art from the prior art. In particular, the addition is achieved via extrusion or compounding.
The present invention provides copolymers (C) for stabilizing polymers, where these bring about a reduction of the melt viscosity of polymers and by virtue of their polymeric structure are less toxic during handling, incorporation, and use as stabilizer. The copolymers (C) used for the purposes of the present invention exhibit excellent properties in particular as hydrolysis stabilizers for polyaddition polymers and polycondensation polymers.
The examples provide further explanation of the invention, but do not restrict the subject matter of the invention.
A copolymer of vinyltriethoxysilane (VTEOS) and glycidyl methacrylate (GMA) was produced in accordance with the processes of WO 2012/098063 A1 with the aid of free-radical polymerization. The production process took place in (26% by weight, based on the entire reaction solution) toluene as solvent at a temperature of 120° C. The molar ratio of VTEOS to GMA was about 1:1 (152.8 g of VTEOS and 113.8 g of GMA). Tert-butyl peroxybenzoate (2.6 mol %, based on the amount of monomers) was added as free-radical initiator. The reaction time was 6 hours. A cloudy, viscous polymer solution was obtained.
Diagram of the linear copolymer of example 1:
A copolymer of glycidyl methacrylate (GMA), methyl methacrylate (MMA), styrene (ST), and methacryloxypropyltrimethoxysilane (TMSMA) was produced in accordance with the processes of WO 2012/044981 A2 with the aid of high-temperature polymerization. The production process was in accordance with example 15 of WO 2012/044981 A2. Table 1 describes the molar ratio of the monomers.
Diagram of the copolymer of example 2:
Polyethylene terephthalate (PET) for producing biaxially oriented foils was purchased from Mitsubishi Polyester Film GmbH, Wiesbaden. The PET had a low concentration of carboxylic end groups (about 21 mmol/kg). The acid numbers were obtained via titration of the respective PET solution in a solvent mixture of chloroform/cresol.
The stabilizers (copolymers (C)) were extruded in various concentrations together with the PET at a temperature of 260° C.
The resultant foils were then exposed to elevated temperatures (110° C.) and high humidity (100%) and stored for a period of two and, respectively, five days (2d, 5d).
The degradation of the polymer was determined via measurement of intrinsic viscosity (IV) and/or of acid end group concentration of the PET prior to and after storage. The IV measurements (units in mg/I) were carried out with the aid of a micro-Ubbelohde capillary viscometer, using a 1:1 mixture of phenol and o-dichlorobenzene as solvent.
Unless otherwise stated, the polymers extruded without stabilizers were in each case used as reference (REF 1, REF 2, and REF IND).
In a comparative experiment (IND REF), Stabaxol I (Rhein Chemie), which is frequently used in industry, was likewise incorporated in PET.
As can be seen from table 2, the copolymers (C) stabilize the PET with respect to hydrolytic degradation. Although resultant concentrations of acid groups are higher, when comparison is made with the Stabaxol results, good stabilization of viscosity properties is surprisingly nevertheless obtained.
| Number | Date | Country | |
|---|---|---|---|
| 61769777 | Feb 2013 | US |
