US3326835A - Intermediate and microcrystalline wax polybutene-1 resin blends - Google Patents

Description

June zo, 1967 R, A, SIGNORELL. ET AL 3,326,835

INTERMEDIATE AND MICROCRYSTALLINE WAX POLYBUTENE-l RESIN BLENDS Filed Sept. 9, 1964 Fly/1X 250 /0 2 A /A/IEPMEDM/'E WAX /fv//E/vr/a/v ATTORNEY United States Patent O 3,326,835 INTERMEDIATE AND MICROCRYSTALLINE WAX POLYBUTENE-l RESIN BLENDS Richard A. Signorelli, Clifton, and Joseph I. Wrozina, Tenafly, NJ., and John J. Kaufman, New Brighton, Pa., assignors to Allied Chemical Corporation, New York, N.Y., a corporation of New York Filed Sept. 9, 1964, Ser. No. 395,205 4 Claims. (Cl. 260-28.5)

This invention relates to petroleum fwax compositions and more particularly to petroleum wax coating compositions widely used in forming protective coatings for wrapping paper and paperboard in the production of low-cost cartons for liquids.

Petroleum wax is deficient in several properties such as creased barrier properties, hardness, grease resistance, and heat sealing properties. Many additives have been proposed -for blending with petroleum Wax to improve the properties thereof.

The petroleum industry generally classifies petroleum waxes in three main categories, namely, (1) paraflins; (2) intermediate; and (3) microcrystalline waxes. Other classes of waxes are known such as the scale waxes and slack waxes; these are low-cost crude waxes. This invention is concerned with the upgrading of the intermediate and microcrystalline waxes, which, as noted, are distinct, well-known grades of refined waxes distinguishable from the parains and also the crude or low-cost waxes such as the scale and :slack waxes. The paraffins are predominantly the normal paraflins, i.e., straight chain saturated hydrocarbons lwith minor amounts of isoparaflins. The microcrystalline waxes are predominantly cyclic saturated hydrocarbons (naphthenes) and iso parati-ins. The intermediate waxes are blends or mixtures of paraffin and microcrystalline waxes. In Table I below is given the ranges of certain physical and .chemical properties of these three classes of waxes.

In Table II below is given physical and chemical properties of three typical commercial waxes, one from each of these three classes.

TABLE II Inter- Micro- Property Paraflins mediate crystaline Gravity, ASTM D-287, API 41. 3 38. 0 34. 4 Melting Point:

ASTM D-87, F 140.1 156. 2 ASTM D-l27, 156.0 173. 5 on calin Point A 1 g g l 153.5 171.5 Penetration, ASTM D132 At 77 F 14 16 10 At 100 F 40 42 30 Flash Point, F 455 515 610 Ultraviolet Absorbtvity at 290 my, ASTM D-2008.. 0.01 0.03 0.23 Iodine Number 0. 4 1. 4 3.2 Molecular Weight 442 539 746 Refractive Index 1. 4359 1. 4434 1. 4562 Distillation, Vacuum Corrected to 760 mm. Hg, 5% Point, F.-- 804 861 967 Patented June 20, 1967 The upgrading of waxes by the addition of additives thereto has .sought to improve the creased barrier properties of the coated material. The property of a coating wax employed for example in the coating of paper, and paperboard, in the manufacture of food wrappers and paper cartons, to minimize passage of moisture vapor through the creased or folded coated paper and paperboard is a most important factor in the commercial acceptance of that coating wax. A standard test widely used in the wax coating art for measuring this property is the creased moisture vapor transmission rate (referred to herein as creased WVTR). This test is described in TAPPI 465 creased WVTR. Briefly, it involves the determination of the weight of water vapor in grams ywhich passes in 24 hours through square inches of accordian pleated test sample containing the specified weight of coating. All values herein for creased WVTR are determined by this test procedure carried out at 100 F. and 95% RH (relative humidity), are tr-uly comparative because the same weight of coating was applied to all test samples (15 pounds per 3000 square feet), and are given in all cases in grams per 100 square inches for a 24 hour test period.

Among other properties sought to be improved by the addition of additives to the wax are the sealing strength of the wax coating and its grease resistance. Sealing strength values are determined by the standard Socony-Vacuum Seal Tester. Samples are pulled at 3 in./min. with a 100 g. load. The values given are the weight in grams required to pull apart two coated specimens which are sealed together under the predetermined temperature, pressure and dwell time specified in the test procedure. In the case-of the test results given in the specification the test specimens were each rectangular, l2 inches along, 2 inches wide, arranged in superimposed relation with a l inch seal at a temperature of 20G-250 F., pressure of 6-10 p.s.i.g. for a dwell ltime of i-LS minutes.

Grease resistance is a measure of the time required for a drop of the specified grease to penetrate through the coated uncreased test specimen. The grease used in the test results given herein was Wesson Oil applied at ambient temperatures and maintained at F. until failure of the coating.

It isa principal object of this invention to upgrade intermediate and microcrystalline waxes with particular reference to i-mproving their creased WVTR, heat sealing properties and grease resistance.

Other objects and advantages of this invention will be apparent from the following detailed description thereof.

In accordance with this invention intermediate and microcrystalline waxes are ugraded by blending therewith from 10% to 40%, preferably 15% to 25%, based on the weight of the coating material (wax plus polybutene-l resin) of a polybutene-l resin having a molecular weight of from 100,000 to 300,000, preferably 100,000 to 200,000, and an isotactic content of from 50% to 75%, preferably 60% to 70%. Thus this invention involves wax coating compositions consisting essentially of intermediate or microcrystalline waxes blended with from 10% to 40%, preferably 10% to 25% of the aforesaid polybutene-l resins.

In this specificati-on all percentages are given on a weight basis.

The wax coating compositions of this invention have outstandingly good creased WVTR values. For example, in the case of an intermediate wax of F. melting point having a creased WV IR of 6.0, the blending with such wax of 25% polybutene-l having an isotacticity of from 65-70% and a molecular weight of 150,000 to 190,- 000 reduced the creased WV IR value to 0.5. The irnprovement in creased WVTR values is significantly better than with commercial additives for waxesincluding the ethylene vinyl acetate copolymers (Elvax 250 and Elvax 420). Furthermore the wax blends of this invention have good heat seal strength, good grease resistance and generally better overall properties than the base wax and the base wax with other additives such as polyethylene, polypropylene and even with polybutene-l resins not having the molecular weight and isotacticity hereinabove given for the polybutene-l resins blended with the intermediate and `microcrystalline waxes.

The discovery that the .blending of the polybutene-l resin having the molecularweight and isotacticity herein disclosed materially improves the creased WV lR values and other properties of the base intermediate 4and microcrystalline wax is indeed surprising and unobvious. Table III which follows gives a comparison of the creased WVTR values obtained by blending in the proportions indicated polybutene-l resin having a molecular weight of 190,000 and an isotactic content of 68% with paraffin, intermediate and microcrystalline waxes, substantially the same as the three typical commercial waxes the properties of which are given in Table III.

While the blending of of this polybutene resin resulted in an increase in the creased WVTR value for the paraffin wax from 15.5 to 16.8 it gave a decrease from`5.8 to 5.6 in the case of the 'inter-mediate wax. The blending of of this polybutene-l resin with the paraffin gave a decrease from 15.5 to 12.6 (an improvement of about 20% based on the 15.5 value of the base wax), whereas the decrease for the intermediate wax was from 5.8 to 1.3 (an improvement of about 80%) and the decrease for the microcrystalline wax was from 9.8 to 1.2 (an improvement of about 88%). Blends of isotactic polybutene-l with parain wax are. more fully described -in our co-pending application Serial No. 395,204, tiled Sept. 9, 1964.

In this specification, the expression isotactic is used in its conventional sense to mean the material in the polymer remaining after extraction with diethyl ether; the isotactic material is substantially insoluble in hexane Iand naphtha. The diethyl ether extraction removes the amorphous or atactic material (which is the material soluble in hexane and naphtha) and leaves a polymer containing the isotac-tic material.

The polybutene-l resin employed in forming the wax blends of the present invention can be prepared by polymerizing butene-l using a Ziegler type catalyst and conducting the polymerization under conditions to produce a polymer having the desired isotactic content of from 50%l to 75% and desired molecular weight of from 100,000'to 300,000. Any of the known Ziegler catalysts can be used; Vfor example, catalysts obtained by reaction between compounds of metals of Group IV-A (titanium, zirconium, hafnium or thorium), V-A (vanadium, columbiu'm or tantalurn), VI-A (chromium, molybdenum, tungsten or uranium) with alkyl compounds of aluminum a or a metal of Group II (beryllium, magnesium, calcium,

strontium, barium, zinc or cadmium). Polybutene produced by polymerization using stereospecic catalysts such as CrO3 or SiOz-AlgOa support or a catalystkconsisting of a promoted M003 may also be used. In all cases the polymerization must be timed and moderated Ato produce ;a polybutene-l having the desired molecular weight and isotactic content. Hydrogen can be introduced into the polymerization reaction mixture to control the molecular weight and percent isotacticity. Polybutene-l polymers having an isotactic content of from 50% to 75 and a molecular weight of from 100,000 to 300,000 produced by any known procedure can be used.

Polybutene-l resins having the above noted isotactic contents and molecular weights blend readily with the intermediate and microcrystalline waxes.

The blending of polybutene-l with the intermediate or microcrystalline wax can be effected in any known or desired manner. A typical procedure for effecting such blending is described below.

A three-necked ask equipped with an electric drive stirrer, a thermometer, and a nitrogen inlet tube is charged with a measured amount of the wax. The Wax is heated under nitrogen with moderate stirring until a clear liquid results. To the melted wax is added a charge of the polybutene-l resin having the molecular weight and is-otacticity and in amount all as herein disclosed. The mixture is heated to a temperature above the melting point of the wax and stirred to assist solution. The mixture can be maintained under a continuous blanket of nitrogen `during the heating and stirring, if desired, and particularly when the heating is carried out under higher temperatures than C. The polybutene-l charge is completely dissolved in the wax -in approximately onehalf hour; this is evident upon visual inspection. Desirably, however, heating of the blend is continued for an additional one-quarter hour to insure complete dissolution of the resin in the wax. The blend is thereupon allowed to cool to( ambient temperature.

In the drawing, FIGURE 1 is a graph showing the creased WVTR plotted against the precent concentration of two polybutene resins, one having a molecular weight of 150,000 and an isotactic content of 64% (hereinafter referred to as PB-l) and the other a molecular weight of 190,000 and an isotactic content of 68% (hereinafter referred to as PB-Z). In this graph line A shows the creased WVTR for the base wax, an intermediate wax having the properties of the typical intermediate wlax of Table II. Curve B is the ygraph for blends of this intermediate wax with both polybutene-l resins; the creased WVTR values for 4blends with both resins are substantially the same. Line C is the graph for blends of the intermediae wax with an ethylene vinyl acetate copolymer (Elvax 250). It will be noted that at concentrations of 15%, the creased WVTR value for the Elvax wax blend is appreciably greater than that for the base wax whereas the blends with polybutene resin have creased WVTR values of about 3 as compared with 5 for the base wax. At 20% concentration the creased WVTR value for the Elv\ax wax blend is about 6 and for the polybutene resin wax blends is about 1.

FIGURE 2 is a graph showing the creased WVTR values plotted against percent concentration for (l) the base wax, an intermediate Wax; (2) a polybutene-l intermediate wax blend of this invention in which the polybutene-l resin is PB-2; (3) lan ethylene vinyl acetate copolymer having a vinyl acetate content of 28% (Elvax 250); and (4) a second ethylene vinyl acetate co-polymer having a vinyl acetate content of about 18% (Elvax 420). The marked and surprising improvement in creased WV IR effected in the base intermediate wax by blending therewith the polybutene-l resins herein disclosed as compared with Elvax is evident from FIGURE 2.

In Table IV which follows is given the comparative creased WVTR values for a microcrystalline wax, substantially the same as the typical microcrystalline wax the properties of which are given in Table II above, blended with polybutene resins PB-1 and PB-Z and for comparative purposes the creased WVTR values of blends of the same microcrystalline wax with an ethylene vinyl acetate copolymer (Elvax 250). The creased WVTR Value of the base microcrystalline wax was 9.8.

Table V which follows gives the Sealing Strength values for blends of intermediate `and mirocrystalline waxes with PB-l and PB-2 resins at 20% and 25 concentrations. The sealing strength of the base intermediate wax was 27 and that of the base microcrystalline wax was 150.

TABLE V Sealing strength Blend: g./ in. width Intermediate 20% PB-l 139 Intermediate 25% PB-Z 167 1 tear seal Microcrystalline 20% PB-l 170 Microcrystalline 25% PB-2 220 1 tear seal 1 Indicates the coated paper tears, i.e., the seal is so strong the paper tears before or at the point where the weight is large enough to break the seal.

Table VI which follows gives the grease resistance of blends of intermediate Wax with PB-l and PB-2 in concentration of and 20%. This test was carried out on uncreased paper with Wesson Oil applied at ambient temperatures and maintained at 105 F,

TABLE VI Blend Blend Time for Grease Percent Percent To Penetrate, le., PB-l PB-Z Failure in Hours The time for the base wax was 1 hour. Thus this test shows a marked improvement in grease resistance properties of the blends of this invention as compared with the base Wax.

Examples of this invention have been give in the above including the tables which include comparative data demonstrating the improvements in creased WVTR values and sealing strength values embodied in the blends of intermediate and microcrystalline wax with polybutene-l resins having a molecular weight of from 100,- 000 to 300,000 and an isotactic content of from 50% to 75% as compared with Iblends of the same base wax with known commercial additives, namely the ethylene polyvinyl acetate copolymers.

The wax blends embodying the present invention are eminently satisfactory for use in existing coating equipment. They can be employed in all lields Where wax coatings of superior creased barrier properties, heat seal strength, or good grease resistance nd application. The blends of this invention, in the molten state, can be applied by known coating techniques to foil, parchment, kraft, glassine, chipboard and other paper stocks to produce packaging materials having an attractive gloss and exceptionally good creased vapor barrier.

10 Since certain changes in the petroleum waX polybutene- 1 blends embodying this invention can be made without departing from the scope of this invention, it is intended that all matter contained in the description shall be interpreted as illustrative and not in a limiting sense.

15 What is claimed is:

1. A petroleum wax blend consisting essentially of a petroleum wax from the group consisting of intermediate Wax distilling within the temperature range of about S-900 F. and microcrystalline wax distilling within the 2O temperature range of about 950-1050" F. and from 10% to 40% by weight of a polybutene-l resin having a molecular weight of from 100,000 to 3000,000 and an isotactic content of from 50% to 75 by weight, said blend having creased Water vapor transmission rate less than that of 25 the petroleum Wax.

2. The petroleum wax blend of claim 1 in which the polybutene-l resin has a molecular weight of from 100,000 to 200,000 .and an isotactc content of from 60% to 70% by weight.

3. A petroleum wax blend of improved creased resistance to transmission of water vapor therethrough and improved heat sealability which consists essentially of an intermediate wax blended with from 15% to 25 by weight of a polybutene-l resin having a molecular weight of from 100,000 to 200,000 and an isotactic content of from 60% to 70% by Weight.

' 4. A petroleum wax blend of improved creased :resistance to transmission of water vapor therethrough and improved heat scalability which consists essentially of a 40 microcrystalline wax blended with from 15 to 25 by weight of a polybutene-l resin having a molecular Weight of from 100,000 to 200,000 land an isotactic content of from 60% to 70% by weight.

References Cited UNITED STATES PATENTS 2,691,647 10/1954 Field et al. 2,824,089 2/ 1958 Peters et al. 260-88.1 2,932,633 4/1960 Iuveland et al 26o-94.9

FOREIGN PATENTS 849,389 9/1960 Great Britain.

r MORRIS LIEBMAN, Primary Examiner'.

B. A. AMERNICK, Assistant Examiner.

Claims (1)

1. A PETROLEUM WAX BLEND CONSISTING ESSENTIALLY OF A PETROLEUM WAX FROM THE GROUP CONSISTING OF INTERMEDIATE WAX DISTILLING WITHIN THE TEMPERATURE RANGE OF ABOUT 825-900*;. AND MICROCRYSTALLINE WAX DISTILLING WITHIN THE TEMPERATURE RANGE OF ABOUT 950-1050*F. AND FROM 10% TO 40% BY WEIGHT OF POLYBUTENE-1 RESIN HAVING A MOLECULAR WEIGHT OF FROM 100,000 TO 300,000 AND AN ISOTACTIC CONTENT OF FROM 50% TO 75% BY WEIGHT, SAID BLEND HAVING CREASED WATER VAPOR TRANSMISSION RATE LESS THAN THAT OF THE PETROLEUM WAX.

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