Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1981-02-05
1983-03-08
Pertilla, Theodore E.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
106111, 106116, 524 2, 524 8, 524 60, C08L 9500, C08L 1102
Patent
active
043761763
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the setting of anionic latices of film forming polymers.
It is sometimes desirable to add substances to latices of film forming polymers, which substances will cause the latex to gel or coagulate to a solid or semi-solid after a certain time has passed, so enabling the latex to be subjected to various processing steps before gelling or coagulation takes place. An example of this is in the production of foam rubber in which air is beaten into a rubber latex, to which a substance has previously been added which will remain inactive for a time while air is incorporated into the latex to produce a foam but which will then cause the latex to gel so as to prevent the foam collapsing. The resulting solid foam can then be heated to vulcanise the rubber. The substance which is conventionally used to obtain this delayed action setting effect in rubber latices is sodium silico-fluoride. The same material is used when gelling is required in latices based on rubbers with other materials which are used in producing ground coverings e.g. for sports tracks and playgrounds. Sodium silico-fluoride however is expensive and it can be difficult to incorporate it into latex compositions economically.
British Patent Specification GB 1 317 603 discloses a process for making a hardenable mixture containing an aqueous dispersion of a natural or synthetic rubber. The specification explains that when the previously known hardenable compositions based on such dispersions are used to make thick sections or coatings such thick sections or coatings harden very slowly. The first stage of hardening is the formation of a skin on the surface exposed to the air through which water can escape only very slowly (e.g. over 1 to 2 weeks).
GB 1 317 603 proposes to overcome this problem by adding a solid particulate coagulant which is capable of taking up water e.g. cement, plaster of Paris. The problem of water elimination is overcome by taking up the water within the composition so that it does not need to escape from the composition. However in order to prevent such a rapid coagulation that the composition cannot be worked satisfactorily e.g. to form a smooth layer on a surface, it is necessary to coat the particles of the solid particulate material with a hydrophobic liquid. This increases the costs and makes the process for manufacturing the compositions more complicated. Furthermore as the water present in the composition has to be taken up by the coagulant it is necessary to use large quantities of coagulant. Thus the smallest quantity of coagulant mentioned in GB 1 317 603 is 15 parts of Portland cement per 100 parts of solids in the dispersion, and this is stated to give a soft product. The typical quantity is said to be 25-100 parts of Portland cement per 100 parts of solids in the dispersion.
We have now found a process for the delayed action setting of latices which does not require the water to be taken up by the coagulant. We have surprisingly found that it is possible to carry out delayed action setting of aqueous latices without the water being trapped within the coagulating material.
Thus it is possible to eliminate a major part of the water within two days of applying a layer of the composition and in the case for example of a playground surfacing material it can be possible to walk on the surface relatively shortly after the surface has been applied. According to the present invention there is provided a process for the delayed action setting of a composition comprising an anionic latex of a film forming polymer by the addition of a delayed action setting agent characterised in that the setting agent is a compound containing a multivalent metal cation, which metal cation compound has a solubility in the range 0.1 g to 150 g per 100 g of water at 20.degree. C. in water and which has a dissolution time greater than 1 minute, the quantity of metal cation compound being not more than 2.5% by weight based on the total weight of composition and not more than 11% based on the weight of film forming polyme
REFERENCES:
patent: 3951900 (1976-04-01), Bath
Pertilla Theodore E.
The British Petroleum Company Limited
LandOfFree
Process for setting a latex of a film forming material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for setting a latex of a film forming material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for setting a latex of a film forming material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1734653