Net Finishing Composition, Process and Product

Technical Field

This invention relates to a compos ition of matter and a process for using same, and more particularly to a net finishing composition for treating nets and the product obtained thereby. Nets, such as fish nets, have from time immemorial been made from natural fibers and have been treated with tar or tar-like materials to protect and enhance the properties thereof. Synthetic materials, such as nylon, polyesters, polypropylene, polyethylene and the like are replacing such natural fibers with nylon presently being in greater demand as a result of the many excellent properties as well as cost considerations.

Nylon, i. e. , the monofilament fiber thereof, is woven to form a twine which is subsequently further woven to form the desired mesh size of the net. To protect the thus formed nylon net or the like, such a net is treated with tar and variations of such natural like materials, much as the natural fiber nets have been treated over the centuries, as well as being treated with various synthetic materials. Such treatments have been found to be relatively ineffective with the resulting coatings or films readily washing off or wearing off the manufactured net. With such washing out or wearing out, exposure of the synthetic material to the elements has caused early breakdown of the net resulting in the surveying thereof or at best retreat ment thereof.

A s hereinbefore mentioned, nylon has found the greatest use in the fish net industry as compared with other synthetics due to its many excellent properties as well as present cost factors, however, nylon has been found to absorb as much as 20% by weight of its weight in water with concomitant loss in fiber strength.

In the manufacture of nets, whether the net is to be used for in sporting events, such as tennis, ping-pong or the like or as fishing nets, the mesh size thereof are set by usage or by governmental regulations. In particularly, the fishing industry, the net mesh size

5 is carefully regulated by the Federal Government, i. e. , mesh size is dictated by the type of fish being subjected to trawling. While use of nylon nets have increased the lifetime of net usage as distinguished from natural fiber nets coated with tar or tar-like substances, the usage lifetime is still relatively short.

10 Disclosure of Invention

The objects of the present invention are achieved by a net finishing composition which is preferably applied by dipping the net mesh substrate into such composition and which is comprised of a low molecular weight, high acetate content, vinyl chloride copolymer, a

15 monomeric plasticizer, a polymeric plasticizer dissolved or dispersed in a solvent system. The plasticizers are present in an amount from 40 to 60 parts, preferably 50 parts per 100 parts of the copolymer with the ratio of monomeric plasticizer to polymeric plasticizer ranging from 1 part to 1 part to 3 parts to 1 part, preferably 2 parts to 1.

20 The solvent system includes ketones and aliphatic and/ or aromatic diluents in the range from 75 to 25 to 25 to 75 parts. In one embodiment of the present invention, a net finishing concentrate is provided wherein the copolymer and plasticizers are dissolved in a solvent system comprised of essentially ketones for subsequent dilution in a further

^• 5 solvent for the treatment of the net.

The net finishing composition of the present invention applied to the net substrates exhibits many properties similar to the properties of the tars as well as many properties superior to the properties of tar used to treat natural fiber nets. In this regard, the resulting net

^' 30 exhibits low physical properties, i. e. , low psig with high elongations. Use of a cabon black pigment has significantly aided in psycological acceptance of the resulting net.

The essential components of the resin system of the present invention are the low molecular weight, high acetate content, vinyl chloride copolymers and the monomeric and polymeric plasticizers. The amount of plasticizers added to the low molecular weight, high acetate content, vinyl chloride copolymer is from 40 to 60 parts, preferably about 50 parts to 100 parts of the copolymer resin. The ratio of the monomeric plasticizer to polymeric plasticizers is from 1 : 1 to 3 : 1, preferably about 2 : 1.

The resin system is dissolved or dispersed in a solvent system such that the solids content of the resulting composition of matter is no less than 20% by weight, and between 20 to 40% solids, with a preferable solids range of 27 to 28% by weight.

A solvent system includes ketones and aliphatic aromatic hydrocarbons wherein the ratio of ketones to aliphatic aromatic diluents are from 25 to 75 to 75 parts to 25 parts with a preferred range of 50 parts of ketones to 50 parts of the aliphatic aromatic diluents. It will be understood by one skilled in the art that an increase in the aliphatic aromatic diluents to ketones would be more economically attractive, as well as, result in a product which more closely resembles a tar coating, although higher concentrations of such aliphatic aromatic result in lower solids content in the net finishing composition.

While the actual mechanism of the present invention is not clearly understood, it is believed that the net finishing composition of the present invention results from the viscosity and slow drying time of the net finishing compostion which permits penetration and monofilament coating of the individual fibers of the woven net, and that penetration and coating continues during drying for a time period substantially greater than the synthetic net finishing composition here- tofore tried in the art which normally results in casting as herein¬ after more fully discussed.

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Of the low molecular weight, high acetate content, vinyl chloride copolymers, I have found that the acetate content should not be less than about 10% by weight and preferably between 15 to 20% by weight of the copolymer resin. The molecular weight of the copolymer should be in the range from 20, 000 to 65, 000 with lower acetate content being associated with the higher molecular weights.

In some formulations, pigments have been added for color effect. I have found that carbon black has demonstrated excellent reinforcing properties as well as to result in a net which is colored similar to the nets used for years in the industry, i. e. psycological acceptance.

As her einabove mentioned, due to shipping cost considerations, concentrates of net finishing compositions may be prepared and shipped which only require the addition of diluent solvents at the user site. In this regard, the herein-above discussed resin system is preferable admixed with 100% ketones to form a 45 to 55% by weight solids solution which solids solution is subsequently diluted by adding any conventional aliphatic and /or aromatic hydrocarbon to achieve proper solids content (20% - 40%) prior to net treating. Of the monomeric plasticizers, of which there are many, I have found D. O. D. P. (dioctyl diphthalate) to be particularly usefully advantageous (cost) in the resin system of the present invention. Of the polymeric plasticizers, which there are many in the art, all the primary polymeric plasticizers have been found useful in the net finishing composition of the present invention.

The net finishing composition of the present invention has been found to be particularly useful, as hereinabσre discussed, in the treatment of nylon netting for salt water usage, and in this regard, the composition of the present invention permits a one-step treatment of the netting. Net treatment is effected by placing the net finishing composition, (or properly solventized concentrate) at ambient temperatures in a trough and continuously introducing and wi th¬ drawing width- wise the net in total immersion in the net finishing

solution for a time from 5 to 10 seconds. The net generally dries to the touch in 1 to 2 hours. It is generally desirable to permit the coated net to cure for at least 72 hours before fishing. It will be appreciated by one skilled in the art that fish nets are of consider- able weight and length an d are not readily handled. Consequently, substantial savings in net handling result through the use of the present invention in that one-step treatment with the composition of the present invention may be effected rather than a double or three-through treatment required when using high molecular co- polymers whereby minimum solids pickup of fro m 20 to 25% is required. It has been additionally found that the use of high molec¬ ular weight, high acetate content resins require weight copolymers which require substantial thinning or dissolution to obtain the required penetration for double or triple dipping. Additionally, double or triple dipping of the net with high molecular weight copolymer essentially results in a casting of the material rather than penetration thereby substantially increasing peeling of the resulting film through handling and abrasion.

It has been found that a nylon net treated with the net finish composition of the present invention results in a coated nylon net of significantly increased strength properties, e. g. , up to 25% stronger than a nylon net alone or nylon net treated with tar or tar-like materials. Additionally, it has been found that the resulting coating or film of the present invention substantially reduces water penetration into the nylon filaments and thereby significantly reduces nylon stretching whereby mesh size will remain substantially constant during the fishing season. Thus, the us e of nylon nets treated in accordance with the present invention as com¬ pared with nylon nets tar treated in accordance with the present art practice has resulted in an increase of a fish (menhaden) catch of as

great as 50% due to the substantial maintenance of the mesh size.

The following example is illustrative of the present invention:

EXAMPLE

A nylon fish net is introduced into the following net finishing compound having the following components :

INGREDIENTS

Low molecular weight, high acetate content, vinyl co¬ polymer - *VC113 100 Monomeric plasticizer 33

(D. O. D. P. ) Polymeric plasticizer 17

**Sanitizer 429 M. I. B. K. ) Solvent - 175 Ketone ) System 175

* Registered Trademark of the Borden Company. ** Registered Trademark of Monsanto.

The treated net is removed from the net finishing com¬ position and is permitted to dry for a period of about three days. Thereafter the net is onloaded to a fishing trawler of a fleet thereof and is found t o substantially improve daily catch and in some instances by as much as 50% when compared with nylon nets treated with tar-like materials on trawlers in the same fleet.

Fouling of nets with organism, such as barnacle-type organism have been an additional problem. I have found that by adding of from 6 - 15 oz. per gallons to the net finishing composition of a series of organo tin esters, e. g. n-tributyl tin succinate, benzoate and linoleate, and quartenary ammonium salts dissolved in a solvent system, that significant anti-fouling effects have re- suited.

While the present invention has been used for the treatment of nylon fish nets of a mesh size for menhaden fishing, mesh sizes as well as length sizes are not relevant to the present invention except as to sufficient contact time between the composition and net being treated. Additionally, while the net material has found use in sal t water fishing, nets treated in accordance with the present inventi

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f r sporting events and for fresh water fishing would similarly benefit, as well as the fact that any form of nylon netting or like synthetic fiber netting, as well as natural fibers could benefit from the use of the present invention. Additionally, other vinyl chloride copolymers could be used, e. g. , a vinylidine vinyl chloride.