Polystyrene binders

Details Polystyrene binders Polystyrene binders

1998-02-11

2004-04-27

Aftergut, Jeff H. (Department: 1733)

Adhesive bonding and miscellaneous chemical manufacture

Methods

Surface bonding and/or assembly therefor

C524S300000, C524S379000

Reexamination Certificate

active

06726798

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to binders based on homopolymers or copolymers of styrene, to their production and to their use for bonding, coating and sealing.
Binders in the context of the invention are substances which are capable of bonding or firmly adhering to substrates of the same or different types. They are generally based on substances, especially polymers, which set chemically or physically. Physical setting consists in solidification from the melt or in the drying of an aqueous or organic solution or dispersion. The substances or rather polymers are generally modified by additives in such a way that they are more suitable for bonding, adhesive sealing and coating. Corresponding additives are, for example, resins, plasticizers, solvents, fillers, pigments, accelerators, stabilizers and dispersants. Accordingly, the adhesives, sealing compounds and coating compounds are based on correspondingly modified binders.
2. Discussion of Related Art
Plasticizers are added to improve the plasticity or to reduce the hardness of adhesives, sealing compounds and coating compositions. Plasticizers are liquid or solid, generally inert organic substances of low vapor pressure. According to general expert knowledge (see Habenicht, Gerd: “Kleben: Grundlagen, Technologie-Anwendungen”, 2nd Edition,1990, page 100), the disadvantage of plasticizer-containing adhesive layers lies in their impaired ageing and adhesion properties and in the reduced strengths of the adhesive layer and in its tendency to creep and migrate. Accordingly, well-balanced consideration has to be given to the priorities between plasticity on the one hand and strength of the other hand. In “Ullmanns Encyclopädie der technischen Chemie”, the use of plasticizers is also described under the keyword “Weichmacher (Plasticizer)” (see pages 371 to 377, Vol. 24, 4th Edition, 1983).
Corresponding compositions of polystyrene and plasticizers are known. Thus, U.S. Pat. No. 4,869,934 describes a composition for the smoothing, cleaning and coating of floors which consists, for example, of the following components: 31.2 parts by weight of a copolymer of butyl methacrylate, methacrylic acid, methyl methacrylate and styrene in a ratio of 10:18:52:20, 1.6 parts by weight of the permanent plasticizer (BuOCH
2
CH
2
O)3PO and 7.0 parts by weight of the volatile plasticizer Me(OC
3
H
6
)
2
OH and around 48 parts by weight of water. This known composition has the disadvantage that the volatile plasticizers at least pollute the environment or are even toxic.
The product “Plastilit 3060” is described in BASF's Technical Information Pamphlet TI/ED 1115 d-1 of January 1984. This product is a polypropylene glycol alkylphenyl ether which is used as a plasticizer for polymer dispersions, more especially for polyacrylates. The polymers specifically mentioned include a copolymer of styrene and butyl acrylate and a copolymer of ethyl acrylate, ethyl hexyl acrylate and acrylonitrile. Corresponding compositions may be used, for example, as sealing compounds with rapid skin formation after application, with relatively little post-curing and with better elongation behavior at low temperatures. In addition, they form with fillers paste-like tile adhesives which combine high tensile strengths with high elasticity. The plasticizer has an elasticizing effect on the copolymer without significantly impairing the water absorption of the film. Thus, the elongation of a film increases substantially linearly from around 300% to 4,000% where 9% of plasticizer is added. So far as the biological activity of the plasticizer is concerned, it is said not to be a health risk although prolonged exposure may well result in irritation of the skin and mucous membrane.
The same disadvantages also apply to the following two publications. Polish patent PL 119091 describes a non-toxic and non-inflammable adhesive for ceramics and plastics which, in addition to an acrylate/styrene dispersion, contains polypropylene glycol alkylphenyl ether, fillers, organic solvents and water.
German patent DE 36 38 224 describes an elastic sealing material which contains a styrene/butadiene rubber, an &agr;-methyl styrene polymer, solvents, such as hydrocarbons and aromatic hydrocarbons, and polypropylene glycol alkylphenyl ether.
Czechoslovakian patent CS 259825 describes a contact adhesive for labels and tapes which mainly contains a copolymer of acrylates, unsaturated carboxylic acids and, optionally, styrene, alkyl styrene or vinyl acetate. Other components are organic solvents, plasticizers such as, for example, polyethylene glycol and polypropylene glycol.
Against the background of this prior art, the problem addressed by the present invention was to provide a toxicologically safe composition of a styrene polymer and a plasticizer free from aromatic constituents which would be suitable for use as a binder and which would provide acceptable adhesion.
DESCRIPTION OF THE INVENTION
The solution provided by the invention is defined in the claims and is characterized in that the styrene polymer contains a relatively large quantity of styrene while the plasticizer is a fatty compound.
The styrene polymer contains styrene or methyl styrene in a quantity of, preferably, more than 30% by weight, in particular more than 50% by weight and, above all, more than 80% by weight of the monomers. Comonomers of styrene or methyl styrene can be acrylates and methacrylates containing 1 to 12 carbon atoms in the alcohol component and, more particularly, 2 to 8 carbon atoms. The acrylates may also contain reactive groups for subsequent crosslinking. Corresponding reactive groups may also contain vinyl comonomers, for example a silane group. The Si(Alk)
3
group may be attached to the vinyl group either directly or by a (CH
2
)
n
radical where n may be a number of 2 to 6 and preferably has a value of 3 or 0. The alkyl groups may contain 1 to 4 carbon atoms and preferably 1 or 2 carbon atoms. Other comonomers can be vinyl esters, maleic acid esters (again containing 1 to 12 and preferably 2 to 8 carbon atoms in the alcohol component), ethylene, acrylamide, acrylic acid, butadiene, acrylonitrile both individually and in the form of mixtures. The molecular weight is above 100,000 g/mole. Commercially available styrene copolymers are: Acronal 290 D, Scopacryl D 343, Ubatol VAF 1539, Acronal S 360 D, Scopacryl PAA D 8875, Acronal S 400, Acronal S 401, Styrofan A 900, Rhodopas DS 913, Joncryl 678, Vinnapas LL 6010 and SAF 54, Neocryl A 621 (styrene/acrylate copolymer), Pliotec LS 1 (styrene/butyl acrylate/methacrylic acid terpolymer), Mowilith DM 611, Mowilith DM 680, Styropor P 555 (pure styrene), Buna EM 2116, Styrolux 684 D, Rhodopas SB 012, (styrene/butadiene copolymer), Novodur P2M, Synthomer VL 10286 (styrene/butadiene/acrylonitrile terpolymer).
The styrene copolymers may be produced by known methods, more particularly by emulsion or bead polymerization. These processes give aqueous dispersions with a concentration of around 40 to 70% by weight of styrene copolymer. However, the styrene copolymers may also be produced in bulk or solution.
It may be regarded as surprising that these aromatic polymers are compatible with the aliphatic fatty compounds. It may also be regarded as surprising—in view of the constant need to dry and degrease the substrate surfaces to ensure firm adhesion—that strength is hardly affected in the process. This is particularly surprising insofar as the content of fatty compounds is not just a few percent, but generally from 0.5 to 60% by weight, preferably from 10 to 50% by weight and, more preferably, from 15 to 40% by weight, based on the binder. The tensile shear strength of adhesives is still >1, preferably >2 and, more preferably, >4 N/mm
2
for beechwood.
“Fatty compounds” in the context of the invention are fatty acids, fatty alcohols and derivatives thereof. Their molecular weight is generally above 100 and preferably above 200. The upper limit is 20,000 and preferably 300 to 1,500.
“Fatty acids” in the context of the i

Affiliated with

Also associated with

Rating

Polystyrene binders does not yet have a rating. At this time, there are no reviews or comments for this patent.

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

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3248386