USRE22438E - Coating composition - Google Patents

Description

- Reissued Feb. 22, i

v .airao s'm'riez's PATENT; OFFICE COATING fifiOSITION I I was aeaassmsia ssss:

vanla Industrial Chemical Corporation, a corporation of Pennsylvania No Drawing. Original No. $319,389, dated May 18, 1943, swarm. 345,860, July 16, 1940. ap- .plication for reissue August 9, 1943, Serial No.

This invention relates to a thermoplastic coating composition purposed particularly as a coating for paper and other fibrous or cellulosicmaterials. such as cloth of different sorts.

Heretofore the substances preponderantly used for coating paper have been paraffin wax and one or more of the more expensive types of resin,

such as coating compositions containing vinyl resins or the polymers of acrylic acid esters.

Paraflln wax is the typical paper coating material, but of itself does not give to a maximum all the desired qualities of a paper coating, in that it tends to opacity, is of relatively low melting point, and'has low resistance to abrasion.

'bocyclic terpene hydrocarbons are, without hydrogenation or other treatment,-highly compatible with paraifln wax to such extent that they blend in all proportions with the wax without granulation in the mixture or separation between 5 Claims. (Cl. 26028) cluded in the composition in sufliciently great proportion, we have also discovered that paper coated with the mixture is translucent and in practical effect transparent, and that it possesses a glossy finish so that the coated paper is suitable for use in display packages for foods and other materials.

. The proportions'in which terpene resins, even those of the highest melting point which have been made, are compatible with paraffin wax are unlimited, so that there may be included in thewax mixture any relative proportions which are desirable or economical in making a composition for use in making any specialized type of coated paper or fabric. In this connection it should be emphasized that the terpene resins require no addition or modification in order that they may possess such broad measure of compatibility with the paraflin wax.

In line with the foregoing, we may make a paper-coating composition containing, for example. 90% paraffin wax, and 10% of high-melting terpene resin. Such composition has good heatsealing properties, in which the parailln wax is of itself deficient, and has a higher gloss and lesser opacity than paraflin wax. We have found that even this relatively small proportional inclusion of terpene resin, and this is particularly true the wax and resin.. Thus, we have discovered.

that we are able successfully to blend with par-. afiin wax the highest melting terpene resins which may be made by polymerizing selected unsaturated constituents of gum spirits of turpentine and other terpene starting materials; such as those high polymers of beta-pinene, and terpene mixtures in which beta-pinene preponderates, which are disclosed in the application of Samuel G. Burroughs, Serial No. 288,390, filed August 4, 1939, issued December 7, 1943, as Patent No. 2,355,912. We havefound that by so doing, we are able to produce with paraflln wax .a homogeneous mixture having a melting pointmuch higher than that oi the parailln wax, and

yet WhichFpoSsesses wax characteristics. Such if the resin has a high melting point such as a melting point of from 250 F. upward, gives a coating composition which, when applied, has better fllrn continuity and better resistance to abrasion than unmodified paraflin wax.

As exemplary of coating compositions capable of rendering paper transparent and giving it a glossy finish, so that it is well suited for the packaging of foods and the like. we may mix paraflin wax and high-melting terpene resin, such as aterpene resin melting about 275 F., in a proportion of from 30% and more of the resin.

A coating composition in which the brittleness of the resin is modified by an addition of wax may be made by mixing the resin with 25% or' even less of paraffin wax. Such composition is useful for glazing paper for purposes in which great transparency or translucency is of primary importance.

In all mixtures of thewax and resin the qualiablend of terpene resin and parafiln Waxes, in

accordance. with the proportional inclusion. of

- the resin and its melting point, has a greater resistance to abrasion than paramn wax, and has better heat-sealing properties than the wax taken by itself. If a terpene resin mixed with the wax is of sufilciently high melting point and is inties imparted to the mixture by the resin are more striking for any proportional inclusion of the 'resin,.the higher the melting point of the resin which is included.

In addition to paraffin waxall the other wax- I like materials, whether or no they be wholly hydrocarbon in nature, are compatible with ter- 2 pene resin of all melting points. Thus, for example, in our thermoplastic coating composition we have made homogeneous mixtures of terpene resin having melting-points up to the highest currently obtainable with ceresin wax', candelilla wax, camauba wax, montan wax, Japan wax: and synthetic waxes, such as those produced by the esteriflcation of long chain alcohols with fatty acids, and hydrogenated fats and oils;

Most of the other wax-like materials lack the chemical resistance of paraflin wax, but otherwise have properties making them useful in a thermoplastic coating composition of the sort with which we are concerned. i

Among the wax-like materials which we may use, parafiln wax may be considered the preferred waxy ingredient, both for reasons of economy, and because its other properties, such as light color, chemicalresistance, and relatively high melting point render it suitable. It is the wax typically usedfor paper coating, and, in

known thermoplastic coating compositions for paper coating and like uses. The usual high grade of ,paraihn waxobtained from petroleum oils melts at about 140 F. Certain other waxlike materials, typically carnauba wax, melt at relatively high temperatures. 4

In our coating composition leis important that the terpene resin be higher melting than the wax -like material with which it is mixed,.in order that the more substantial advantages coming from its inclusion may be had. This is true with whatever one, or more of the wax-like materials itmay be'mixed. It follows that, in order to obtain compositions having properties best suited to particular materials to be coated, and particular uses to which'the materials thus coated are to be put, we vary the melting point of the terpene resin and its proportionalinclusion in accordance with the melting temperature of the waxlike material for any intended use of the composition. .It is roughly true that inclusion of the terpene resin in any proportion with a wax-like material proportionally modifleslthe properties of that material, and inclusion of a wax-like matev rial in any proportion with a terpene resin proportionallymodifles the properties of the resin.

, Because of the compatibility of the highest melting terpene resin with all wax-like materials, and because there is nothing critical about the proportional inclusion of the ingredients of the composition, it is a simple matter to apportion the ingredients of the composition in accordance with their melting properties and the intended use of the composition. Thus, we may give, as roughly illustrative, a coating composition for a coated paper of good heat-sealing properties consistingessenti'ally of about 90% paraflin waif 'melting at about 140" F. and about 10% -of tor-.-

pene resin melting at about 300 F. As a composition for glazed paper for use in display packages and the like, we may give as roughly exemplary a composition consisting essentially. of about40%- paraflln wax melting'at about 140- F. and about 60% of terpene resin melting at'about 250! PL, For a composition having primarily the properties of a plasticized resin, we may give as roughly exemplary one consisting essentially of about parailin wax melting at about 140 F.

r and about 75% of terpene resin melting at about 275 F. It is a simple matter to obtain varied desired properties of the coating composition by varying the proportions of the ingredients and by selecting tho-ingredients on'the basisoftbeir melting temperatures. By reference to the melting temperatures of all the various other waxlike materials, it is also a simple matter to make up from the other wax-like materials and terpene resin coating compositions which parallel the paraiiin-wax compositions in the properties dependent upon the melting characteristics of the ingredients.

All variants-oi the terpene-containing coating composition above described are thermoplastic compositions, and by this we mean that in applying them they are caused to flow by heat. They thus may be prepared for application, and may be applied by any procedure known to be suitable for the application of coatings of paraffin-wax and other wax-like materials, or coating compositions consisting essentially of such materials and ingredients other than terpene resins. The mixture of the ingredients is made by fusing them together, and may be applied either as made or by refusing the mixture.

its intimate association with the wax-like material, or materials with which it is mixed. It may be applied to paper or fabric in any of the wellknown methods by which they have been coated; as by immersion, hot-spraying, use of the doctor knife, or working in hot rolls. It may be applied to the surfaces of more substantial bodies, in any way known to be suitable for applying thermoplastic coatings; as by immersion or hot-spraying.

Our coating composition, consisting essentially of an unaltered and relatively inexpensive terpene resin and a wax-like material, which may be the relatively inexpensive paraflin wax, thus has commercial advantage over coating compositions 01 similar sort whichlnclude with the wax in ying ingredients of some more expensive It has, in comparison with the wax alone, greater resistance to abrasion, better heat -sealing prop erties due to the inherent tendency of the resin to act as a thermoplastic adhesive, gloss and transparency in higher order, and the ability to'im- I prove, the capacity of paper coatedwith it to receive a suitable printing ink without blurring Other advantageous qualities of our coating I composition are attributable to the wholly hydrocarbon nature of its terpene resin content. For

1 other reagents.

' under.

example, that resin tends to impart to the coating composition its own inherent qualities of chemical resistance to acids, alkalis, salts; and

It also tends to-impart tothe coating composition in which it is included re-. sistance to enzyme reactions,'and thus to'render paper or fabric coated with it suitable for use in packaging foods. If, as is usual, we include the terpene resin with paraiiin wax, which is also wholly hydrocarbon in nature, the coating composition possesses those qualities in maximum To our base coating composition, co ting essentially of a wax-like material and a highermelting terpene resin, other ingredients for imparting specific additional qualities may be added;

Thus, a number of high molecular weight strength-increasing substances are compatible both with the paraflln wax, or otherwax-like material, and with the terpene resin. For example,

we may add to the composition a minor pr portion of strength-increasing substances, such as the polymers of isobutylene, thelower polymer ized forms of the higher-esters of acrylic acid,

such as butyl-methacrylate, worked rubber; the

resin content Ofrubber, and rubber 4 In eithe case the melting temperature of the resin is lowered by exemplified by. chlorinated rubber; making such addition'to the essential composition when highly elastic coatings are desired.

Additions, such as those above noted, may be made to our essential composition without departure from our invention, and while remaining within the definition of that invention as contained in our appended claims.

We claim as our invention:

1. The herein-disclosed thermoplastic coating composition consisting essentially of a homogeneous mixture 01 paraflin wax and thermoplastic and25% to 90% oithewax.

3. The herein-disclosed thermoplastic coating composition consisting of a homogeneus mixture of parafiin wax and thermoplastic terpene resin melting higher than the paraffin wax and composed of polymers of unsaturated pinene constituents of turpentine in' the approximate proportion of 10% to 75% of the terpene polymers and 25% to 90% of the wax.

4. The herein-disclosed thermoplastic coating composition consistin essentially of a homogeneous mixture of a wax and thermoplastic terpene resin melting higher than the wax and composed of polymers of unsaturated pinene constituents of turpentine.

5. The herein-disclosed thermoplastic coating composition having as its major component a homogeneous mixture of a wax andthermoplastic terpene resin melting higher than the wax and composed of polymers of unsaturated pinene constituents of turpentine.

FRANK w. CORKERY. v SAMUEL G. BURRQUGHS.