MXPA97002024A - Basic mix formulation for depoliolef applications - Google Patents

Abstract

Basic blends comprising high density polyethylene (HDPE) are used for the production of polyolefin articles, particularly films. Using the HDPE in a basic mixture alone or in combination with a hydrocarbon resin and / or a polyolefin ultimately results in extruded polyolefin articles of stiffness and optimum utility. Using a high density polyethylene in combination with a hydrocarbon resin and a polyolefin in a basic mixture, it causes the basic mixture to solidify more quickly and can be granulated more efficiently.

Description

"FQg ULTIMATE BASIC MIXING FOR POLYOLEFINE APPLICATIONS" This invention relates to basic blends and their method for use in producing polyolefin articles, particularly films. The high density polyethylene can be incorporated into the base mixture alone or in combination with a hydrocarbon resin and / or a polyolefin, and when used in combination with a hydrocarbon resin causes the base mixture to solidify more rapidly and granulate more efficiently (improved mixing efficiency). These basic blends ultimately result in extruded polyolefin articles such as molded polyolefin films of optimum stiffness and ductility. Polyolefins are useful plastic materials to produce a wide variety of valuable products due to their combination of stiffness, ductility, barrier properties, temperature resistance, optical properties, availability and low cost. Being a semi-crystalline polymer, a number of these important properties such as stiffness, barrier properties, temperature resistance and optical properties depend on the ability of the polyolefin to crystallize in the most effective manner, and to the desired degree.

The process to form a polyolefin product strongly affects the crystallization behavior of the material and its final properties. For example, when the polypropylene is molded into a thin film, the polymer cools so rapidly that the final crystallinity level is reduced by this "rapid cooling" process and correspondingly the stiffness of the film is reduced. Molded polypropylene films typically exhibit a stiffness, which is measured as a tension modulus, of nominally 7.03 K kilograms per square centimeter. Highly oriented polypropylene (OPP) films typically exhibit modulus values of 2 to 4 times greater than the values for the molded polypropylene film, while non-oriented coarse molded articles typically exhibit modulus values nominally of 50 percent a 100 percent higher than the molded polypropylene film. Also when producing a molded film it is important that the polypropylene melt solidify rapidly to promote high production rates, and also that the crystalline regions that are formed are not so large in size as to impart turbidity to the film. Other molded polyolefin articles, particularly thin gauge products produced by thermoforming, injection molding or blow molding, are subject to similar restrictions. The faster crystallization that allows rapid demolding and stiffer products is desirable as well as the good optical properties promoted by the small crystalline domain size. As a means to improve the rigidity of polyolefins, the addition of a high softening temperature hydrocarbon resin to polyolefins, such as polypropylene, is already known. The composition of the hydrocarbon resin should be such that it exhibits a significantly higher glass transition temperature (Tg) than the amorphous regions of polypropylene (Tg around -10 ° C) and the hydrocarbon resin should be highly compatible in polypropylene. It is believed that the effect of the hydrocarbon resin is to increase the Tg of the amorphous polypropylene fraction and in doing so increases its modulus of tension at temperatures below 38 ° C. The hydrocarbon resins described above are brittle solids which exhibit very low melt viscosity at the temperatures normally used to process the polyolefin. An effective way to mix the hydrocarbon resin in the polyolefin is in a separate mixing step before the final use of the mixture. It is difficult to incorporate the hydrocarbon resin into the polypropylene during an effective conversion step (e.g., film molding, sheet extrusion, etc.) due to the characteristics of sprinkling of hydrocarbon resins and low melt viscosity. A more effective way to incorporate the hydrocarbon resin into the polyolefin during the conversion step is to add the resin in concentrated form as a mixture of resin with polyolefin. US Patent Number 5,213,744 describes a process for forming a concentrate consisting of a single binary mixture of hydrocarbon resin and polyolefin, and using this concentrate as a more effective way to incorporate the hydrocarbon resin into the polyolefin film formulation at a level of 5 percent by weight to 30 percent by weight. Although the stiffness caused by adding the hydrocarbon resin is desirable, it can be achieved only by adding high levels of hydrocarbon resin (typically at or above 5 weight percent) to the total polyolefin formulation and only if the softening temperature of The hydrocarbon resin is 100 ° C or higher, the stiffening effect increases as the content and softening temperature of the hydrocarbon resin increases. Even though the stiffening effect caused by the addition of hydrocarbon resin to the polyolefins is desirable, the addition of high levels of resin (e.g., greater than 5 weight percent) has a negative impact on ductility and results at an increased formulation cost. Therefore, it would be highly desirable to improve the rigidity of the polyolefin by adding hydrocarbon resin to the polypropylene at levels of less than 5 weight percent, preferably less than 3 weight percent. Before any further discussion, a definition of the following terms will aid in the understanding of the present invention. Basic mixture - a mixture of two or more ingredients that simplifies adding these ingredients to a material as a mixture instead of a plurality of individual ingredients. In the present case, basic mixture is defined as a mixture of one or more ingredients (additives) in the appropriate proportion by weight with a polymer or mixture of polymers, wherein the total formulation is finally added to a second polymer, which is either the same or different than the polymer or mixture of polymers comprising the basic mixture, as the means to incorporate the additives in the second polymer. Additive - an additive is typically a substance that is added to a polymer that is non-polymeric in nature, or if it is of a polymeric nature is considerably different in type and character of the polymer to which it is added. In the present case, the additive refers to both the hydrocarbon resin and the high density polyethylene (HDPE) which are finally mixed with the polyolefin. By our definition, HDPE is considered an additive even though it could also be considered a polymer in the context of the definition of basic mixture. Polyolefin Blend - the final formulation resulting from the combination of a base mixture with a polyolefin polymer or a mixture of polymers. Accordingly, the polyolefin polymer or polymers wherein the base mixture is included is referred to as the blend polyolefin. Hydrocarbon Resin - refers to low molecular weight resin products of a number average molecular weight of 10,000 (Mn) or less that are derived from polymerization feed materials from the coal or petrochemical industries, resin products derived from terpene, rosin and other food materials. This term will not be used to refer to high molecular weight polymer products of a number average molecular weight of 50,000 or more.

As discussed above, the addition of a high softening temperature hydrocarbon resin to a polyolefin, such as polypropylene, will increase the glass transition temperature (Tg) of the amorphous phase of the polyolefin and modify its properties. An effect of the addition of hydrocarbon resin is greater rigidity. However, to achieve a significant property modification, the hydrocarbon resin must be added at levels of or greater than 5 weight percent of the total polyolefin mixture. The addition of high levels of hydrocarbon resin has a negative impact on the ductility and impact properties, increases the cost of the formulation, and slows down the polyolefin crystallization rate. Therefore, it would be desirable to achieve the favorable effects of the addition of hydrocarbon resin at lower hydrocarbon resin addition levels. The present inventor has discovered that by adding low levels of high density polyethylene (HDPE) to a polyolefin such as polypropylene, it accelerates the crystallization rate of the polyolefin when high density polyethylene (HDPE) is properly dispersed in the polyolefin and the ingredients they are added effectively. It appears that under fast cooling conditions, HDPE crystallizes more rapidly than polyolefin and as HDPE begins to crystallize, it acts as a nucleator for the subsequent crystallization of polyolefin. Accordingly, the present invention is directed to basic blends for modifying polyolefins, wherein the base mixture is a combination of a hydrocarbon resin and a high density polyethylene (HDPE) mixed with a polyolefin polymer, or a binary mixture of HDPE with a polyolefin, or a binary mixture of a high density polyethylene and a hydrocarbon resin. The components of the basic mixture must be combined intimately using conventional techniques, such as: dry mixing, extrusion mixing and melt blending and granulation. In another embodiment, the basic mixture is provided in the form of a granule by mixing the melt and granulating the components of the basic mixture. Adding the HDPE and a hydrocarbon resin to a polyolefin polymer as a basic mixture prior to the extrusion of the article results in favorable characteristics in the final article. In addition, the present inventor has discovered that adding low levels of HDPE to a polyolefin, such as a basic mixture, without the hydrocarbon resin, provides modifications of the desirable property of the finished product.

In each case, the ingredients and the weight ratio of the ingredients in the basic mixture are such that they are intimately mixed in a formulation during the final processing step to produce a final article. In one embodiment of the present invention, the basic blend for modifying the polyolefin polymers comprises from 10 percent to 90 percent by weight of high density polyethylene, and a hydrocarbon resin alone or in combination with a polyolefin. The polyolefin may be present in a concentration of up to 85 weight percent of the total base mixture, and may be any alpha-olefin polymer comprising monomers containing from 2 to 8 carbon atoms with propylene polymers being especially preferred. The polyolefin can be an ethylene polymer with a density up to 0.930 gram per cubic centimeter. In another embodiment, the polyolefin is selected from the group consisting of polypropylene and polypropylene polymers with up to 20 weight percent of monomers that are selected from the group consisting of ethylene and mono-alpha olefin of 4 to 8 carbon atoms. The polyolefin in the basic mixture is selected to be similar to the polymer of the mixture or if it is significantly different from the polymer of the mixture, which is present in low levels in the basic mixture, so that it is incorporated at low levels (less than 5%). percent by weight) in the final mixture. The hydrocarbon resin and the high density polyethylene can be present at a combined concentration of 15 percent to 100 percent by weight of the total base mixture, and the hydrocarbon resin and the high density polyethylene can be in a relative proportion in weight from 0: 1 to 10: 1 in the basic mixture, as long as the concentration of the high density polyethylene never exceeds 40 percent by weight of the total basic mixture unless the ratio by weight of the resin from hydrocarbon to high density polyethylene in the basic mixture is at least 0.5: 1 or greater. In another embodiment of the base mix, high density polyethylene has a density greater than 0.935 gram per cubic centimeter and a melt index greater than 1.0 gram / 10 minutes, while the hydrocarbon resin is a compatible aliphatic resin of one weight molecular average in number of 10,000 or less, with an odorless mineral alcohol cloudiness (CMS) of less than 0 ° C and a ring and ball softening temperature of 100 ° C or higher (obtained through the use of Method 28-67 of the American Society for the Testing of Materials). In another basic mixing mode, the hydrocarbon resin is an aliphatic compatible resin having a WHO clouding temperature of less than -40 ° C. The cloudiness temperature of odorless mineral spirits (OMS) was determined by the following test. Ten percent by weight (10%) of the resin is placed in a test tube containing ninety percent by weight (90%) of an odorless mineral spirits (OMS) which is Shell-Sol 71 (obtainable from Shell Chemical Company , Houston, TX). The test tube containing the sample is heated until a crystalline solution is formed. The solution is then cooled until the turbidity of the solution is observed. The initiation of turbidity is recorded as the initial cloudiness temperature. The cooling of the solution is continued until the solution is completely cloudy. The final turbidity temperature is the temperature at which the total turbidity is observed. In additional embodiments of the base mix, high density polyethylene may have a density greater than 0.950 gram per cubic centimeter or a density greater than 0.960 gram per cubic centimeter and a melt index greater than 5.0 grams per 10 minutes or greater. 10.0 grams per 10 minutes, respectively. In another embodiment of the base mix, high density polyethylene has a density of .950 gram per cubic centimeter or greater, and a melt index of between 10 to 30 grams per 10 minutes. In another embodiment, the base mixture may comprise a hydrocarbon resin and a high density polyethylene in a weight ratio of hydrocarbon resin to high density polyethylene from 0.5: 1 to 4: 1. In one embodiment, the composition of the basic mixture comprises a polypropylene, for example, a propylene homopolymer such as polyolefin. In another embodiment, the basic blend for modifying the polyolefin polymers comprises from 5 percent to 50 percent by weight of high density polyethylene, from 30 percent to 60 percent by weight of hydrocarbon resin, and from 10 percent to 10 percent by weight. 45 weight percent polypropylene. In another embodiment, the basic blend for modifying the polyolefin polymers comprises from 5 percent to 25 percent by weight of high density polyethylene, from 40 percent to 60 percent by weight of hydrocarbon resin, and from 25 percent to 25 percent by weight. 45 weight percent polypropylene. For example, a basic blend for modifying the polyolefin polymers may comprise 15 weight percent high density polyethylene, 50 weight percent hydrocarbon resin and 35 weight percent polypropylene. In another embodiment, the basic blend for modifying the polyolefin polymers comprises 40 weight percent high density polyethylene, 40 weight percent hydrocarbon resin and 20 weight percent polypropylene. In yet another embodiment, the basic blend for modifying the polyolefin polymers comprises from 15 percent to 50 percent by weight of high density polyethylene and 50 percent to 85 percent by weight of polypropylene. Other embodiments include 40 percent to 50 weight percent high density polyethylene and 50 percent to 60 weight percent polypropylene. In another embodiment, the basic blend for modifying the polyolefin polymers comprises 30 weight percent high density polyethylene and 70 weight percent polypropylene. The present invention is also directed to modified polyolefin blend compositions that result in the mixing of the ingredients of the basic blend described above into a polyolefin polymer using conventional equipment, such as an extrusion apparatus. twin screws.

Accordingly, in another embodiment of the present invention, a modified polyolefin composition comprises a polyolefin, from 0.3 percent to 4.0 percent by weight of high density polyethylene and up to 5 percent by weight of a hydrocarbon resin. In the modified polyolefin composition, various polyolefins may be used, for example, a polymer comprising a mono-alpha-olefin containing from 2 to 8 carbon atoms, with propylene polymers being preferred. The polyolefin can be an ethylene polymer with a density of less than 0.930 gram per cubic centimeter. In one embodiment, the polyolefin is selected from the group consisting of polypropylene and polypropylene polymers with up to 20 weight percent of monomers that are selected from the group consisting of ethylene and a mono-alpha-olefin of 4 to 8 carbon atoms . In one embodiment of the modified polyolefin blend, the high density polyethylene has a density greater than 0.935 gram per cubic centimeter with a melt index greater than 1.0 gram per 10 minutes. In the additional mixing modalities, the high density polyethylene may have a density greater than 0.950 gram per cubic centimeter or a density greater than 0.960 gram per cubic centimeter, and a melt index greater than 5.0 grams per 10 minutes or greater than of 10.0 grams per 10 minutes, respectively. In the modified polyolefin blend, the high density polyethylene has a density of .950 gram per cubic centimeter or greater and a melt index of between 10 and 30 grams per 10 minutes. In another embodiment of the modified polyolefin blend composition, the modified polyolefin composition comprises from 1.5 percent to 2.5 percent by weight of a high density polyethylene and from 2 percent to 3.5 percent by weight of a high density polyethylene resin. hydrocarbon, wherein the polyolefin comprises polypropylene. In the modified polyolefin composition, the hydrocarbon resin can be an aliphatic compatible resin with an Mn of 10,000 or less, which has an odorless mineral spirits (OMS) soak temperature of less than 0 ° C and a softening temperature of Ring and ball of 100 ° C or higher. In addition, the modified polyolefin composition may comprise an aliphatic compatible hydrocarbon having a cloudless odorless mineral alcohol (OMS) temperature of less than -40 ° C. In one embodiment, the modified polyolefin composition comprises a polypropylene homopolymer such as polyolefin modified by a basic mixture comprising a hydrocarbon resin and an HDPE. In one embodiment, the polyolefin composition can be modified by combining 6 percent of a basic mixture comprising hydrocarbon resin and HDPE with the mixed polyolefin. The modification of the polyolefin by the addition of low levels of hydrocarbon resin and HDPE achieves several improved properties. First, the addition of low levels of hydrocarbon resin and HDPE increases the modulus of tension value of the polyolefin by 15 percent to 70 percent above the value of the polyolefin polymer itself. More typically, increases of 20 percent to 50 percent are achieved through this modification. A principle, but not exclusive of the use for formulations of this type is in a molded film wherein the highest stiffness is a desirable quality. Second, modified polypropylene blends altered in this manner have an improved crystallization behavior wherein the mixture will solidify (crystallize) from the melt more quickly and / or differently than the unmodified polypropylene. This effect is important in many manufacturing processes such as film production, blow molding, injection molding and sheet thermoforming, where the productivity of optical quality depends on the speed and nature of the crystallization process. Therefore, the modified blends are useful for forming various articles such as films, fibers, bottles, molded articles and sheets. Finally with respect to the modified polypropylene mixture, the addition of the hydrocarbon resin and HDPE as modifiers does not deteriorate the optical properties of the mixture, and in some cases it improves the optical quality. Thin molded films (.0254 to .102 mm thick) produced from these modified polypropylene formulations demonstrate excellent clarity, low turbidity values (less than 5 percent as measured by Company Method D-1003). American for Materials Testing), and also high values of 45 ° gloss or gloss from 70 percent to 90 percent (measured by D-2457 method of the American Society p >for the Materials Test). This last effect was especially unexpected. Intuitively, it is to be expected that adding HDPE to polypropylene will greatly increase the turbidity and will lead to surface roughness and low gloss or luster. However, the good optical properties are retained or improved by incorporating low levels of an effective quality of a high density polyethylene, if it is intimately dispersed in the final polypropylene mixture according to the present invention.

Additional aspects of the present invention are directed to the process and result in polyolefin articles formed from the polymer blend compositions resulting from mixing a basic mixture as described above in a polyolefin, and mixing and extruding of the modified polyolefin to form a polyolefin article. Accordingly, the present invention is directed to a process for producing a polyolefin article which comprises providing a basic mixture which may comprise from 10 percent to 90 percent by weight of high density polyethylene and at least one member that is selected of the group consisting of polyolefin and hydrocarbon resin. The polyolefin may be present at a concentration up to 85 weight percent of the total base mixture, and various polyolefins may be used, for example a polymer comprising mono-alpha olefin monomers containing from 2 to 8 carbon atoms, with the propylene polymers being preferred. The polyolefin can be an ethylene polymer with a density up to 0.930 gram per cubic centimeter. In one embodiment, the polyolefin is selected from the group consisting of polypropylene and polypropylene polymers with up to 20 weight percent of monomers that are selected from the group consisting of ethylene and a mono-alpha-olefin of 4 to 8 carbon atoms . The hydrocarbon resin and the high density polyethylene can be present at a concentration of 15 percent to 100 percent by weight of the total base mixture, and the hydrocarbon resin and the high density polyethylene can be present in a proportion of Weight from 0: 1 to 10: 1 in the basic mixture, as long as the concentration of the high density polyethylene never exceeds 40 percent by weight of the total mixture of the basic mixture unless the weight ratio of the hydrocarbon resin to high density polyethylene in the basic mixture is at least 0.5: 1 or higher. The basic mixture can be mixed by melting and granulating. The basic mixture is subsequently mixed with the polyolefin to form a polyolefin blend which is then extruded to form a polyolefin article. In one embodiment of the present invention, the polyolefin blend extruded to form the polyolefin article comprises from 2 percent to 25 percent by weight of the base mixture, with from 4 percent to 10 percent by weight of the basic blend it is preferred, and further comprises from 0.3 percent to 4.0 weight percent high density polyethylene and up to 5 weight percent hydrocarbon resin. In one embodiment, the polyolefin blend comprises 6 percent of the basic mixture. In another embodiment of the present method, the high density polyethylene has a density greater than 0.935 gram per cubic centimeter and a melt index greater than 1.0 gram per 10 minutes and the hydrocarbon resin is an aliphatic compatible resin with an average molecular weight in number of 10,000 or less with an odorless mineral spirits (OMS) clouding temperature of less than 0 ° C and a ring and ball softening temperature of 100 ° C or higher. In a preferred embodiment of the present process, the basic mixture comprises a hydrocarbon resin and a high density polyethylene in a weight ratio of hydrocarbon resin to high density polyethylene of 0.5: 1 to 4: 1. In another embodiment of the present method, the basic mixture comprises 4 percent to 10 percent by weight of the polyolefin blend, with 6 percent by weight being preferred. In another embodiment of the method, the polyolefin blend comprises from 1.5 percent to 2.5 weight percent high density polyethylene and from 2 percent to 3.5 weight percent hydrocarbon resin. In another process mode, the polyolefin polymer comprises polypropylene, such as a polypropylene homopolymer, in the basic mixture and the final polyolefin mixture. In one mode of the process, the basic mixture comprises from 5 percent to 50 percent by weight of high density polyethylene, from 30 percent to 60 percent by weight of hydrocarbon resin and from 10 percent to 45 percent by weight of polypropylene and the polyolefin in the polyolefin mixture comprises polypropylene. In another embodiment, the basic mixture comprises 15 weight percent high density polyethylene, 50 weight percent hydrocarbon resin and 35 weight percent polypropylene, and the polyolefin in the polyolefin blend comprises polypropylene. In another embodiment, the basic blend comprises 40 weight percent high density polyethylene, 40 weight percent hydrocarbon resin and 20 weight percent polypropylene, and the polyolefin in the polyolefin blend comprises polypropylene. In another embodiment of the process, the basic blend comprises from 15 percent to 50 percent by weight of high density polyethylene, and from 50 percent to 85 percent by weight polypropylene, and the polyolefin in the polyolefin blend comprises polypropylene . In another embodiment, the basic mixture comprises 40 or 50 percent by weight of high density polyethylene, and 50 percent or 60 percent by weight of polypropylene. In another embodiment, the basic blend comprises 30 weight percent high density polyethylene and 70 weight polypropylene, and the polyolefin in the polyolefin blend comprises polypropylene. In another embodiment of the present invention, the polyolefin articles are produced according to the aforementioned method. Polypropylene articles that cool very quickly, such as molded film, benefit from an additive that improves rigidity by increasing the level of crystallization in the film. Also, other than thin molded articles, where the optical properties and rigidity are important attributes, benefit from an additive that favorably affects the crystallization process and also improves the rigidity of the product. Accordingly, polyolefin articles that benefit from the composition and methods of the present invention include blow molded polypropylene products, thermoformable polypropylene sheet products, and polypropylene fiber products. In another embodiment, the extruded polyolefin article is a film comprising a high density polyethylene and at least one member selected from the group consisting of polyolefin and hydrocarbon resin. For example, the film may comprise high density polyethylene, polyolefin and hydrocarbon resin or a high density polyethylene and polypropylene. The polyolefin in the film may comprise a polymer comprising mono-alpha olefin monomers containing from 2 to 8 carbon atoms. In another embodiment, the polyolefin comprises polypropylene. In the first at of the present invention, basic mixtures comprising a polyolefin and a high density polyethylene are provided; a hydrocarbon resin of a high density polyethylene and a combination of a polyolefin, a high density polypropylene and a hydrocarbon resin, wherein the basic blend components are present in effective amounts to increase the stiffness of the final article containing the polyolefin. The formulation of the basic mixture can be used in polypropylene applications, such as in molded polypropylene films but is not limited exclusively to this area. The basic mixture must be able to mix with the polyolefin before the processing step and mix uniformly in the final product (eg, the molded film) homogenizing in the product during the processing step (typically extrusion).

Suitable hydrocarbon resins for use as additives in the base blend are compatible aliphatic products derived from rosin, terpene, or hydrocarbon feedstocks having a ring and ball softening temperature (R &B) of 70 ° C or higher . These hydrocarbon resins have a number average molecular weight (Mn) as measured by vapor phase osmometry less than the molecular weight of the polyolefin. Suitable hydrocarbon resins have a number average molecular weight of less than 10,000, with Mn hydrocarbon resins of less than 5,000 being preferred, for example, hydrocarbon resins of at least 500 to 2000 Mn. The hydrocarbon resins include aliphatic resins compatible with an odorless mineral spirits (OMS) cloudiness of less than 0 ° C, but preferably less than -40 ° C, and with a softening temperature R &B of 100 ° C. or greater, with completely hydrogenated terpene or hydrocarbon resins having a softening temperature of 120 ° C or higher that are preferred and those with a softening temperature R &B of between 135 ° C and 160 ° C being especially preferred. Examples of hydrocarbon resins include REGALITE® R-125 Resin, REGALREZ® 1139 Resin, and REGALREZ® 1128 Resin, which are hydrogenated resins with an R & B softening temperature of more than 120 ° C, all of which can be obtained of Hercules Incorporated. A hydrocarbon resin for use in this application are the fully hydrogenated hydrocarbon resins with a softening temperature R &B greater than 135 ° C. For example, the hydrocarbon resin REGALREZ® 1139 (obtainable from Hercules Incorporated) is a hydrogenated hydrocarbon resin of low molecular weight that exhibits a high Tg (about 90 ° C) and is highly compatible with aliphatic polymers. Other similar hydrocarbon resins exhibiting low molecular weight, aliphatic compatibility and high softening temperature can also be used with similar efficacy such as those hydrocarbon resins described in US Patent Number 5,213,744. When used in a basic mixture, the hydrocarbon resin is believed to act as a "diluent" that compatibilizes the mixture of the two different polymers. The hydrocarbon resin also acts to reduce the melt viscosity of a basic polymer mixture, which improves the ability to completely disperse the ingredients of the basic mixture in the final mixture. When added to polypropylene, the hydrocarbon resin is associated with the amorphous phase of the polyolefin and raises the Tg of the amorphous phase of the polyolefin and finally its modulus.

The high density polyethylene polymers suitable as additives for the basic mixture are those having a density greater than 0.935 gram per cubic centimeter. Preferably the density should be greater than 0.950 gram per cubic centimeter, with the HDPE especially preferred having a density of 0.960 gram per cubic centimeter or greater. The percentage of crystallinity of the HDPE increases with the increased density, and therefore the density is a rough measure of the HDPE capacity to initiate crystallization. The effectiveness of HDPE depends on achieving a finely dispersed and complete distribution of the HDPE through the final polyolefin blend. As a result, the efficiency of the HDPE depends on the degree of dispersion of the HDPE in the basic mixture, combined with the efficiency of the basic mixture to disperse the HDPE through the polyolefin mixture. In order to effectively disperse in the formulation of the basic mixture, the molecular weight (MW) of the HDPE must be appropriately low. The fusion index (MI) (Method D-1238 of the American Society for the Testing of Materials, 190 ° C and load of 2.16 kilograms) is a good indicator of relative molecular weight and flow. He HDPE graduates effectively in this application in case you have an MI greater than 1.0 gram for 10 minutes, and preferably greater than 5.0 grams for 10 minutes. Especially preferred are HDPE grades with an MI greater than 10 grams per 10 minutes. For example, an effective quality of HDPE is a quality that has an MI value of between 10 to 30 grams per 10 minutes (190 ° C, 2.16 kilograms) and a density of 0.950 gram per cubic centimeter or greater. HDPE having a lower MW and higher flux is desirable because both factors make it easier for HDPE to be dispersed through the polyolefin into finer and more numerous domains. However, if the MI is too thin, the fluidity of the melt may be excessive and prevent the effective dispersion of the HDPE in the polyolefin. HDPE with the highest density exhibits the fastest and most complete crystallization behavior. HDPE that exhibits an intense affinity to crystallize is desirable. A highly effective HDPE for use in this invention is the ALATHON H6611 polymerase (from Lyondell Petrochemical Company) having an MI of 11.0 grams per 10 minutes, and a density of 0.965 gram per cubic centimeter. Although it is not restricted to a specific mechanism, it is believed that the function of HDPE in the formulation of the basic mixture is to modify the crystallization behavior of the polyolefin, preferably the homo-polypropylene. HDPE does not function as a bulk alloy ingredient that is its function in conventional applications but rather behaves like a nucleator; an agent that can accelerate the crystallization regime or change the crystallization behavior of a material, even when used at very low levels. Desirable base blend compositions contain additive concentrations that incorporate sufficient amounts of the high density polyethylene polymer together with a hydrocarbon resin and / or a polyolefin to achieve the desired blend compositions with improved properties. In the formulation of the base mix both the high softening temperature hydrocarbon resin and the HDPE are considered active ingredients or additives. The concentration of the active ingredients in the basic mixture can vary from 5 weight percent to 100 weight percent. A scale of active ingredients is from 50 weight percent to 100 weight percent. According to one embodiment, the additives are present in the basic mixture at a level of 15 percent to 80 percent by weight while the polyolefin is from 20 percent to 85 percent by weight. In another embodiment, the additives are present at from 15 percent to 100 percent by weight while the polyolefin levels of the basic mixture are from 0 percent to 85 percent by weight. In another embodiment, the additives in the basic mixture are present at 80 weight percent, while the levels of the polyolefin basic mixture are 20 weight percent. The acceptable weight ratio of hydrocarbon resin and HDPE that will provide the required property modification will vary from a hydrocarbon resin / HDPE weight ratio of 0/1 (no resin added, 100 percent HDPE as the active agent) up to a weight ratio of 10/1. A scale of compositions is between a weight ratio of hydrocarbon resin / HDPE from 0.5 / 1 to 4/1. In the formulation of the basic mixture, the HDPE concentration should never exceed 40 percent by weight of the total mixture, unless the weight ratio of the hydrocarbon / HDPE resin is 0.5 / 1 or greater. In the formulation of the basic mixture, various polyolefins can be used, for example a polymer comprising mono-alpha olefin monomers containing from 2 to 8 carbon atoms, with propylene polymers being preferred. The polyolefin may have an ethylene polymer with a density less than 0.930 gram per cubic centimeter. In another modality, the polyolefin is selected from the group consisting of polypropylene and polypropylene polymers with up to 20 weight percent of monomers that are separated from the group consisting of ethylene and a mono-alpha-olefin of 4 to 8 carbon atoms. Accordingly, the polyolefin polymer may comprise a homopolymer of an olefin of 2 to 8 carbon atoms or a copolymer of 2 or more olefins of 3 to 8 carbon atoms, inclusive, but not being limited to propylene, buten-1, hexene and 4-methylpenten-l. The present invention can also employ a random copolymer of ethylene and propylene such as an isotactic propylene-ethylene copolymer with a density of 0.86 to 0.92 gram per cubic centimeter as measured at 23 ° C according to the D-1505 method of the American Society for the Testing of Materials and a melt flow index of 2 to 15 grams per 10 minutes, as determined in accordance with Method D1238 of the American Society for the Testing of Materials (conditions at 230 ° C and 2.16 kilograms). The propylene copolymers can be synthesized using conventional polymerization methods employing catalysts such as AICI3 and TÍCI4. Polyolefins that fit within the aforementioned definition are described in U.S. Patent No. 5,213,744. The polyolefin portion of the basic mixture is selected to be similar to the polymer to which the melt mixture will be added, or if it is significantly different that it is present in amounts in the basic mixture so that it is present at levels less than 5 percent by weight in the polymer article. With respect to the base mix formulations used for film applications, various grades of polypropylene polymer are preferred, for example, a high molecular weight, semi-crystalline, semi-crystalline polypropylene. If a more rigid molded polypropylene film is desired, the polypropylene homopolymer is especially preferred. Polypropylene melt flow regimes (230 ° C, 2.16 kilogram load) of 0.5 to 50 grams per 10 minutes can be used in the present invention with between 2 to 10 grams per 10 minutes being preferred and an MFR between 2.0 to 5.0 grams per 10 minutes, being especially preferred. The melt flow rate (MFR) of the basic mixture and the MFR of the polymer of the polyolefin mixture help to determine the efficiency with which the polyolefin, the basic mixture, is distributed. If the polymer of the polyolefin mixture exhibits low MFR, the basic mixture will be better distributed if it also exhibits an MFR typically between 2 times and 20 times the value of the polyolefin polymer. If the polymer of the mixture has a higher MFR, then a formulation of the basic mixture with a higher MFR than in the previous case is of course desirable, again nominally from 2 times to 20 times the MFR of the polyolefin polymer in where the basic mix will be combined. The base mix formulations of this invention can be used to produce scales of polyolefin blend compositions containing high density polyethylenes alone or in combination with a hydrocarbon resin exhibiting improved mechanical and optical properties. These polyolefin compositions can be particularly useful in molded film applications. • ** »* ' The polyolefin mixture should incorporate the necessary additives at addition levels of the base mixture from 2 percent to 25 percent by weight, with 4 percent to 10 percent by weight being preferred, and between 4 percent to 8 percent by weight. 100 percent by weight being especially preferred. The polymer of the polyolefin blend in the final polymer formulation comprises any polymer grade or polymer blend as described above for the basic mixture, which can be altered to the extent described by modifiers (e.g., resin). of hydrocarbon and HDPE) present in the basic mixtures. For example, the polyolefins used in the final mixture used to produce the extrudate, for example a film, can be selected from one of the aforementioned polyolefins which are mentioned as being appropriate in the basic mixture. Although the polyolefin used in the base mixture and the polyolefin used in the mixture may differ, it is preferred that they be similar. In one embodiment, the present invention is directed to a final polymer formulation comprising the modified polypropylene polymer by the addition of basic blends containing low levels of HDPE alone, or together with a hydrocarbon resin. The resulting polyolefin blend exhibits improved properties compared to the properties of the polyolefin polymer alone. In another embodiment, the formulations comprise a modified polypropylene by melt blending with low levels of hydrocarbon resin and HDPE. The final mixture exhibits any or all of the following properties, A) Modulus values that are 15 percent to 70 percent greater than the unmodified polypropylene polymer value, B) Higher crystallization behavior and C) Turbidity values comparable to or better than unmodified polypropylene. The polypropylene homopolymer is modified more effectively by the additives described above and is preferred in the application of a molded film of this invention. In molded films, polypropylene homopolymer having an MFR of 2 to 10 grams per 10 minutes, (230 ° C, 2.16 kilograms) is of course preferred. A typical MFR for the polypropylene homopolymer used in molded film applications, for which the invention is particularly directed, is nominally 7 grams per 10 minutes. At hydrocarbon resin addition levels of 5 weight percent or more, the hydrocarbon resin will have detrimental effects on ductility and impact properties. Because of this last restriction, it is preferred that the hydrocarbon resin be incorporated into the final polyolefin formulation (e.g., polypropylene) at hydrocarbon levels of from 0 percent to 5 percent by weight, but preferably at levels of 2 percent to 3.5 percent by weight of the final propylene mixture. While it is known that high temperature softening hydrocarbon resins that are added to polyolefins, preferably polypropylene, can increase the modulus of the polyolefin, the present inventor has discovered that combining low HDPE levels with low resin levels Hydrocarbon is an even more effective way to reduce rigidity to polyolefins such as polypropylene. Even when this subject is investigated, it has surprisingly been known that the addition of low levels of HDPE alone to the polyolefins can also lend considerable rigidity to the polyolefin. From then on it is surprising that the above-mentioned low HDPE levels added to the polyolefin obtain a significant improvement in the polyolefin's mechanical properties, as demonstrated in the examples presented below where the addition of between .7 by percent to 3 weight percent, of HDPE (most preferably 1.5 to 2.5 weight percent of HDPE) to polypropylene increased the tensile modulus of the material by 20 percent to 50 percent. Low HDPE addition levels are therefore preferred because at higher HDPE levels, the improvement in polyolefin properties is lost and / or other negative attributes caused by the presence of HDPE are observed. In one embodiment of the invention, the HDPE can be incorporated into the modified polypropylene formulation at a level ranging from 0.3 percent to 4.0 percent by weight, with the addition of HDPE from 0.7 percent to 3.0 percent by weight being preferred, and an HDPE addition of 1.5 percent to 2.5 weight percent being especially preferred. At lower HDPE levels (e.g., less than 0.3 weight percent) it is difficult to reproducibly affect the mechanical properties of the polypropylene formulation even when good dispersion exists. At higher levels (v.gr, greater than 4 weight percent) the size of the HDPE domain increases with increased levels of addition causing an increase in turbidity and a decrease in ductility. Accordingly, another embodiment is directed to the incorporation into a polypropylene polymer of 2.0 percent to 3.5 weight percent of a high softening temperature hydrocarbon resin along with the required low level of HDPE, which is preferably added to a level of 0.7 percent to 3.0 percent by weight. In addition, the properties of the polypropylene polymers can also be greatly improved by mixing low levels of HDPE in the polypropylene, typically at levels of between 0.7 percent to 3.0 percent by weight, exclusive of the use of the hydrocarbon resin. The present invention will also be illustrated by the following Examples.

Examples 1 to 3 In Examples 1 and IB of Comparison a mixture consisting of a hydrocarbon resin was stirred.

REGALREZ® 1139, manufactured by Hercules Incorporated, and a HIMONT PD-403 polypropylene homopolymer (obtained from Himont Incorporated) using a twin screw extrusion apparatus B13ABENDER model D-6, which contains two counter-rotating twin interlocking screws that they are operated at approximately 100 revolutions per minute. The temperature of the extrusion apparatus during feeding is approximately 150 ° C and the temperature of the extrusion apparatus in the nozzle is approximately 220 ° C. The extrusion apparatus is operated under critical feeding conditions in order to maximize the resistance time in the extrusion apparatus. Under these conditions, the sample is mixed in the extrusion apparatus for about 2 to 5 minutes in order to completely melt and homogenize both components before being subsequently granulated. In Example 2, a mixture of the hydrocarbon resin REGALREZ® 1139 (50 percent) combined with Polypropylene PD 403 from Exxon Chemical (35 percent) and HDPE ALATHON M6210 from Lyondell (15 percent) were mixed dry. Subsequently the mixture was homogenized and granulated using a twin screw extrusion apparatus in the same manner as in Example 1. In Example 3, a mixture of 70/30 Polypropylene PD 403 and HDPE ALATHON M-6210 was stirred or mixed likewise in Examples 1 and 2. In Example IB, a basic mixture was made according to the process of Example 1 with the exception that the Polypropylene used was ESCORENE 4292 Polypropylene which was of 2.0 MFR quality of polypropylene manufactured by Exxon Chemical. Each product described in Examples 1 to 3 was finally extruded as a strand in a 610 meter long water bath to solidify the melt before granulation. It was observed that the high level of hydrocarbon resin REGALREZ® 1139 in Example 1 slowed down the crystallization / solidification process such that the strand was not rigid enough to be cut cleanly after a period of time of 40 seconds had elapsed. after leaving the cooling bath. In Example 2, the presence of HDPE accelerated the solidification process such that the strand was stiff and could be sharply cut 20 seconds after leaving the cooling bath. In Example 3, which does not contain hydrocarbon resin, the strand is sufficiently rigid to be granulated immediately after leaving the cooling bath.

Example Contents of Speed Content of Resin RR1139 HDPE Strand (meters / second) 1.1B 50 percent 4.57 (comp.) 2 15% of M6210 3 30% of M6210 (continuation) Example Strand Length Required Solidification Time (Required Cooling Bath-Granulator) (Granulator-Cooling Bath) 3. 05 meters 40 seconds 1.52 meters 20 seconds 0.0 meter 0 seconds The slow solidification of Comparison Examples 1 and IB made it difficult to efficiently convert this mixture into granule form. The faster solidification caused by the addition of HDPE ALATHON M-6210 in Example 2 made the process more efficient.

Examples 4 to 7 In Example 4, a molded film mixture was prepared by extruding the ESCORENE 4193 molded film grade polypropylene obtainable from Exxon Chemical Corporation having an MFR of 7.5 grams per 10 minutes through a 15.24 cm wide film using an apparatus of 19.05 millimeter Brabender single screw extrusion. The molten polymer was molded on a cooling metal roll cooled with water at 40 ° C and stretched to a thickness of 0.0381 mm, adjusting the surface speed of the molding rolls relative to the extrusion rate of the polymer. In Example 5, a mixture of 94/6 of SCORENE 4193 PP combined with 6 percent of the REGALREZ® 1139 concentrate of Example 1 in a molded 0.0381 mm film under identical conditions used to prepare the films of Example 4. In this and the subsequent Examples the mixing of The additives of the concentrate in the polypropylene matrix is achieved during the extrusion step of the film. In Example 6, similar films were produced wherein a compound containing 6 percent of the concentrate [REGALREZ 1139 + HDPE] of Example 2 was extruded into a film under the same conditions as in Examples 4 and 5. In Example 7 , molded films were prepared under conditions identical to the previous Examples where a 94/6 mixture of Escorene 4193 was used with the concentrate of Example 3. The tensile properties of each of the film samples of Examples 4 to 7 they were measured as mentioned in the table presented below.

Example Additive% of Turbidity% RR-1139 HDPE (%) 4 - . 4 - - - 5.7 (comp.) 5 (comp.) 6%. 1 3 - 5.7 6 6%. 2 3 0.9 8.2 7 6%. 3 -3 1.8 - (Continuation) Example Elastic Limit Stress Module (K kg / cm2) (K kg / cm2) MD / TD MD / TD 4 (comp.) .214 / .220 7.17 / 8.01 5 (comp) .239 / .216 9.07 / 8.51 6 .255 / .245 9.49 / 9.49 7 HDPE Gels HDPE Gels The films of Example 5 containing hydrocarbon resin-REGALREZ 1139 exhibited higher stiffness (modulus of tension) and higher MD yield strength than the films prepared in Example 4 that do not contain the hydrocarbon resin additive. Comparable films of Example 6 containing a low level of HDPE ALATHON M-6210 in addition to REGALREZ 1139 exhibited higher modulus and yield values than the films of Example 5 that do not contain HDPE. The films produced according to Example 7 were very poor in quality due to the poor dispersion of the HDPE of the basic mixture of Example 3 through the Polypropylene matrix. The films were of inferior quality and exhibited poor ductility in the transverse direction. In Example 6, the presence of low levels of HDPE increased the effectiveness of the hydrocarbon resin REGALREZ 1139 by increasing the stiffness of the molded film. By itself, HDPE has no desirable effect because it can not be homogeneously dispersed in the polypropylene during the step of molding the film.

Examples 8 to 13 In Example 8 (comparison), molded films of Escorene 4292 polypropylene were produced which can be obtained from Exxon Corporation having a nominal MFR of 2.0 grams per 10 minutes. The films were produced in a manner similar to the procedure in Example 4, using a molding roll that was cooled with water of 40 ° C with the exception that the speed and extrusion rate of the molding roll was adjusted to produce films of a thickness of .0762 mm. In Example 9 (comparison), the film samples were produced according to the procedure used in Example 8 with the exception that the polymer feed was a mixture of 94/6 of polypropylene ESCORENE 4292 combined with the basic mixture of Example 1, such that the final film contained 3 percent hydrocarbon resin REGALREZ 1139. In Example 10, the films were produced in the same manner as in the previous Examples with the exception that the feed of the polymer of a 94/6 mixture of the ESCORENE 4292 polypropylene and the basic mixture described by Example 2, wherein the final film contained 3 percent REGALREZ 1139 and 0.9 percent HDPE ALATHON M6210. The tensile properties of these films were measured in both the machine direction and the transverse direction as mentioned in the table below. By comparing the values, it can be seen that the presence of HDPE in Example 10 increased both the modulus of tension and the elastic limit of the molded films compared to both the unmodified polypropylene film (Example 8) and the film containing REGALREZ 1139 but not HDPE (Example 9). In Example 11 (comparison), the molded polypropylene film was produced in the same manner as in Example 8 with the exception that the speed of the molding roll was increased to reduce the thickness of the film to .0381 mm.

In Example 12 (comparison), the molded film thickness of .0381 millimeter was produced in a manner similar to Example 11 with the exception that the polymer composition was identical to that in Example 9, the film containing 3 percent of REGALREZ 1139. Likewise in Example 13, similar to 0.0381 millimeter film was produced using a polymer blend used in Example 10 where the final film contained 3 percent REGALREZ 1139 and 0.9 percent HDPE ALATHON M6210. The tension properties of the films produced are listed in the table below. Comparing Examples 8 to 13, the tension modulus of the thin films was not increased to the same degree as the modulus of the thicker films by the addition of either the REGALREZ 1139 resin or the resin combined with HDPE ALATHON M6210. Example 12 compared to Example 13 demonstrates that there is no additional effect on the tension modulus of the HDPE addition together with the REGALREZ 1139 resin.

Example Additive Thickness of% of Film RR-1139 HDPE 8 (comp.) - 0.081 mm - 9 (comp.) 6%. . 1 0.084 mm 3 10 6%,. 2 0.076 mm 3 0.9 11 (comp.) - 0.038 mm - 12 (comp.) 6%. . 1 0.041 mm 3 13 6%. , 2 0.043 3 0.9 (Continuation) Example Elastic Limit Stress Module (K kg / cm2) (K kg / cm2) MD / TD MD / TD (comp.) 7.87 / 7.87, 212 / .202 9 (comp.) 8.23 / 8.44, 203 / .196 10 9.91 / 9.- .238 / .219 11 (comp.) 6.9 / 6.96, 193 / .188 12 (comp.) 7.24 / 7.52 192 / .187 13 7.59 / 7.73 188 / .186 Comparing Examples 8 to 13, it can be seen that for each polymer composition that reduces the thickness of the film, the tension modulus of the final film was decreased. As the thickness of the film is reduced, the polymer melt cools more rapidly and crystallization is forced to occur at lower temperatures. This effect prevents the ability of the polymer to crystallize which leads to lower modulus values in the thin molded films. It was observed that the highest modulus values observed for films containing both the hydrocarbon resin REGALREZ 1139 and the HDPE ALATHON M6210 could not be developed under limited film thickness conditions combined with the temperature of the molding roll. Reducing the thickness of the film or decreasing the temperature of the cast roll both have the effect of preventing the ability of the polymer to crystallize from the melt, and both conditions greatly reduced the efficiency of low levels of HDPE ALATHON M6210 to modify the mechanical properties of the molded polypropylene film. The synergistic effect of adding HDPE together with hydrocarbon resin for molding the polypropylene film formulations appears to be related to the effect of HDPE on the crystallization of the polypropylene during the film molding step. This effect is not achieved by the generic addition of low levels of HDPE in the formulation. The desired effect is effected by the type of HDPE added, the degree of dispersion of the HDPE in the polymer melt and the crystallization conditions during the step of film molding. It is highly desirable to use a basic mixture formulation [hydrocarbon resin + HDPE] which is much less sensitive to the film molding conditions than the formulation of Example 2.

Examples 14 to 17 In Example 14, a mixture consisting of [50 percent hydrocarbon resin REGALREZ 1139 + 15 percent HDPE ALATHON H6611 (Lyondell) + 35 percent ESCORENE 4292 pp] was mixed and extruded in the form of granule in the same manner as the concentrated products of Examples 1 and 2. In Example 15, a similar concentrate mixture was produced except that ALATHON H5121 was the type of HDPE added at a 15 percent level. Example 16 was a similar basic mixture containing 12.5 percent HDPE ALATHON H5234 while in Example 17 the basic mixture contained 12.5 percent HDPE ALATHON H5618. Mixtures represented by Examples 14 to 17 exhibited faster solidification of the extruded strand than the mixture without HDPE, which is represented by Example 1, and both could be granulated more efficiently. These types of HDPE are polymer injection molding qualities, and differ from the M6210 quality of Example 2 as will be described below.

Example Content Content of HDPE of REGALREZ 1139 2 50% 15% of ALATHON M6210 14 15% of ALATHON M6611 15 15% of ALATHON H5112 16 12.5% of ALATHON H5234 17 12.5% of ALATHON H5618 (Continuation) HDPE Fusion Index Example Density of (ASTM Method D-1238) HDPE (gr / cm3! 2 1.0 0.962 14 11.0 0.966 15 12.0 0.951 16 34.0 0.952 17 18.0 0.956 The M6210 quality is a higher MW extrusion quality HDPE. The molecular weight MW is higher can negatively affect the ability of the polymer to disperse uniformly in a mixture and can slow down the crystallization of the dispersed HDPE in this mixture under fast cooling conditions such as when the thin molded films are produced.

Examples 18 to 25 In Example 18 (for comparison), a molded film with a thickness of .0508 millimeter of the ESCORENE 4292 polypropylene was prepared in the same manner as the films of Examples 4 to 7, by molding the melt of mold rollers cooled by water of 50 ° C. In Example 19 (comparison), a film was prepared in a manner similar to Example 18 of a mixture of ESCORENE 4292 PP with 7 percent of the REGALREZ 1139 hydrocarbon resin concentrate at 50 percent that is described in Example IB. In Example 20, a molded PP film was prepared according to Example 18 of ESCORENE 4292 PP with 7 percent of the basic mixture of Example 14, containing 50 percent of REGALREZ 1139 + 15 percent of HDPE ALATHON H661. In Example 21, a similar film of a mixture of ESCORENE 4292 PP was prepared with 7 percent of the basic mixture of Example 15 containing 50 percent REGALREZ 1139 + 15 percent HDPE ALATHON H5112. The tensile properties of these molded films were measured as mentioned in the table below. It can be seen that the films containing the hydrocarbon resin REGALREZ 1139 exhibited a significantly higher tensile modulus while the films produced from the basic mixtures containing ALATHON H6611 or HDPE H5112 in addition to the hydrocarbon resin REGALREZ 1139 exhibited still modulus values. higher values together with values of elastic limit to the highest tension. In Examples 22 to 25, films molded in an identical fashion as the films of Examples 18 to 21 were prepared with the exception that the water for the molding roll was 40 ° C instead of 50 ° C. The tensile properties of these films were measured and compared to the values of the previous Examples in the table below. The lower temperature of the cast roller causes the treated melt to crystallize at a low temperature and reduce the level of final crystallinity. This effect in turn leads to lower values of tension modulus and elastic limit as measured in Examples 22 to 25. In Example 24, which contains HDPE ALATHON H 6611 in addition to 3.5 percent of REGALREZ 1139, the film molded retained the higher values of modulus elastic limit while the film of Example 25, which contains HDPE ALATHON H5112, exhibited somewhat lower values. The film of Comparison Example 23 containing 3.5 percent of REGALREZ 1139 without added HDPE, exhibited a smaller increase in tensile modulus, and elastic limit with respect to the produced film of 100 percent ESCORENE 4292 PP (Example 22 of Comparison) than the films that additionally contain HDPE. In these previous Examples, the addition of REGALREZ 1139 lent greater rigidity to the molded polypropylene films, while the films containing also 1.05 percent HDPE were even more rigid. The influence of HDPE is possibly a synergistic effect on the crystallization of the polypropylene during the molding step of the film. The ALATHON H6611 which is a highly crystalline HDPE (density of 0.966) was particularly effective in this application.

Example Additive Tempera- Caliber or% of Thickness of RR-1139 HDPE Thickness Mold the film (ml) 18 (comp.) - 50 ° C 1.9 19 (comp.) 7%. IB 2.0 3.5 20 7%. 14 1.6 3.5 1.05 21 7%. 15 1.9 3.5 1.05 22 (comp.) _ 40 ° C 2.0 23 (comp.) 7%. IB 1.9 3.5 24 7%. 14 2.0 3.5 1.05 7%. 15 2.0 3.4 1.05 (Continued) Example Turbidity Modulus Elastic Limit (%) (K kg / cm2) (K kg / cm2) MD / TD MD / TD 18 (comp.) 7.8 7.45 / 7.87 209 / .211 19 (comp.) 6.9 8.93 / 8.79 224 / .216 5.9 9.35 / 9.70 240 / .245 21 5.5 9.56 / 9.42 242 / .238 22 (comp) 4.3 7.03 / 6.89 194 / .186 23 (comp) 2.4 7.94 / 8.08 206 / .197 24 2.5 9.35 / 9.35 235 /. 226 25 2.6 8.44 / 8.44 218 / .217 Examples 26 to 33 In Examples 26 to 29 molded PP films were produced according to the procedure of Examples 18 to 21 except that Amoco 82-6721Y polypropylene was used and the water for the molding roll was 35 ° C.

In Examples 30 to 33, PP films molded according to the four previous examples were produced with the exception that the water of the molding roll was increased to 42 ° C. Polypropylene 82-6721Y is one of 7.5 grams per 10 minutes of MFR quality produced by .Amoco for molded PP film applications. The properties measured for these films are listed in the table below.

Example Additive TemperaCalibre or% of Thickness of RR-1139 HDPE Thickness Film (ml) 26 (comp.) - 35 ° C 1.9 27 (comp.) 7%,. IB 1.8 3.5 28 7%,. 14 1.8 3.5 1.05 29 7%. . 15 1.8 3.5 1.05 (comp.) - 42 ° C 2.0 31 (comp.) 7%. , IB 2.0 3.5 32 7%. . 14 1.7 3.5 1.05 33 7%. . 15 1.7 3.5 1.05 (Continued) Example Turbidity / Modulus Elastic Limit Brightness (K kg / cm2) (K kg / cm2) (%) MD / TD MD-TD 26 (comp.) 3.8 / 77 7.87 / 7.80 .199 / .199 27 (comp.) 3.0 / 80 8.08 / 8.72 .205 / .209 28 5.1 / 81 5.81 / 81 .236 / .238 29 4.6 / 82 4.6 / 82 9.63 / 9.70 30 (comp.) 6.1 / 71 7.94 / 7.80 .206 / .206 31 (comp.) 5.7 / 70 8.72 / 8.86 .215 / .219 32 4.6 / 81 10.62 / 10.40 .254 / .252 33 4.8 / 79 9.77 / 9.84 .241 / .236 Molded PP films containing only REGALREZ 1139 additive exhibited marginally higher values of modulus of elastic limit, while films containing also 1.05 percent of HDPE exhibited significantly higher values. Again, ALATHON H6611 quality HDPE with a density of 0.966 was particularly effective in combination with the REGALREZ 1139 hydrocarbon resin to provide stiffness to molded PP film.

Examples 34 to 43 In Example 34 a molded PP film of Amoco polypropylene 82-6721Y was produced in a manner similar to Example 26, except that the water of the casting roller was graduated at 28 ° C. In Example 35 (comparison), a film was produced as in Example 34 except that 7 percent of the basic mixture of REGALREZ 1139 of Example IB was mixed with the polypropylene. In Example 36, a film similar to the previous Example was produced wherein the basic mixture added is described by Example 14, which contains HDPE ALATHON H6611 in addition to REGALREZ 1139. In Example 37, a film similar to the previous Examples was produced wherein the basic mixture added is described by Example 16, which contains 12. 5 percent HDPE ALATHON H5234 plus REGALREZ 1139. In Example 38, a film similar to that of the previous Examples was produced wherein the basic mixture added is described by Example 17, which contains 12.5 percent HDPE ALATHON H5618 in addition to REGALREZ 1139. In Examples 39 to 43 prepared molded PP films in the same manner as the films of Examples 34 to 38 with the exception that the cooling water temperature of the molding roll was increased to 50 ° C. The tensile properties of the films prepared in these Examples are listed in the table below.

Example Additive Tempera- Caliber or% of Thickness Tough RR-1139 HDPE Molding of the film (ml) 34 (comp.) - 28 ° C 1.3 35 (comp.) 7%. IB 1.7 3.5 - 36 7%. 14 1.7 3.5 1.05 37 7%. 17 1.5 3.5 1.05 38 7%. 18 1.5 3.5 1.05 39 (comp.) - 50 ° C 1.5 40 (comp.) 7%,. IB 1. 9 3.5 - 41 7%. . 14 1. 7 3.5 1.05 42 7%. . 17 1. 5 3.5 1.05 43 7%,. 18 1. 5 3.5 1.05 (Continuation) Example Turbidity / Modulus Limit Elastic Luster (K kg / cm2) (K kg / cm2) (%) MD / TD MD / TD 34 (comp.) 1.2 / 85 7.7 / 7.38 .189 / .181 35 (comp.) 0.9 / 90 8.72 / 8.51 .217 / .212 36 4.4 / 81 9.42 / 9.14 .231 / .225 37 3.4 / 79 9.28 / 9.63 .232 / .230 38 3.2 / 82 8.86 / 9.28 .221 / .215 39 (comp.) 10.5 / 44 8.72 / 8.79 .223 / .222 40 (comp.) 13.0 / 60 9.49 / 9.63 .235 / .229 41 4.2 / 79 12.58 / 11.88 .292 / .285 42 3.3 / 83 11.11 / 11.11 .269 / .257 43 3.8 / 79 12.30 / 11.60 .288 / .273 As stated in the previous Examples, adding the hydrocarbon resin REGALREZ 1139 to the polypropylene formulation increased the stiffness of the molded PP films prepared from the mixture, and incorporating low levels of HDPE increased the rigidity even more synergistically. Various kinds of HDPE were used in Examples 34 to 43 to modify the mechanical properties of the molded PP films with good effect under a scale of film molding conditions. The HDPE materials were injection molding grades with a lower molecular weight which allowed them to be more easily distributed in the polypropylene formulation and allowed the material to crystallize more easily under conditions of rapid cooling. It is important that the HDPE incorporated in the hydrocarbon resin base mix can modify the properties of the molded polypropylene film even when the thickness of the film is thin or the molding temperature remains at the low end of typical molding conditions. films .

Examples 44 to 46 In Example 44, a formulation of the REGgALREZ 1139 basic mixture of 40 percent hydrocarbon resin REGALREZ 1139 + 20 percent HDPE ALATHON H6611 + 40 percent PP ESCORENE 4292 was melt blended and granulated in the manner described in Examples 14 to 17. In Example 45, a similar basic mixture containing 40 percent hydrocarbon resin REGALREZ 1139 + 40 percent HDPE ALATHON H6611 + 20 percent PP, ESCORENE was prepared 4292. In Example 46, a basic mixture similar to Examples 45 and 46 was prepared by combining 30 percent HDPE ALATHON H6611 with 70 percent PP, ESCORENE 4292. It will be noted that formulations of the basic mixture containing high levels of hydrocarbon resin solidify slowly due to the slower crystallization rate than the mixtures containing the amorphous resin. It was also observed that adding HDPE to these formulations of the hydrocarbon resin base mixture caused the molten mixture to solidify and stiffen more rapidly, allowing basic mixtures containing HDPE to granulate more efficiently during mixing. This effect is related to the effect of HDPE on the crystallization rate of the formulations of the hydrocarbon resin base mixture. The crystallization properties of various formulations of the basic mixture of REG.ALREZ 1139 and HDPE in polypropylene were measured by differential scanning calorimetry (DSC) where polymer blends were cooled from melting at 25 ° C per minute to room temperatures , and the total heat of crystallization and the maximum temperature of crystallization having been measured by this method. The crystallization properties of DSC of various formulations of the basic mixture of REGALREZ 1139 with or without additional HDPE are listed in the table below.

Example Content Content REGALREZ 1139 HDPE (%) ALATHON H6611 - 100% ALATHON H5112 - 100% Escorene 4292 PP - - 1 (comp.) 50 - 14 50 15% 15 50 15% 40 45 40 40% 40 60% (Continued) Example Crista Heat - Maximum Crystallization Temperature (Joules / gram) (° C) ALATHON H6611 192.8 105.5 ALATHON H5112 141.5 106.8 Escorene 4292 PP 80.7 102.4 1 (comp.) 42.3 91.8 14 59.9 97.9 15 54.8 92.7 - 49.6 95.3 45 92.6 112.6 - 110.8 110.8 Compared to polypropylene, HDPE exhibits a higher heat of crystallization and faster crystallization. The fastest rate of crystallization is indicated by the smallest degree of cooling to less than the maximum melting temperature of the polymer required for crystallization to occur in the HDPE compared to PP. In the basic mixtures of REGALREZ 1139, those formulations containing HDPE in addition to the hydrocarbon resin REGALREZ 1139 exhibited both a higher crystallization temperature and a higher crystallization heat. Both effects contribute to the faster rate at which basic hydrocarbon resin blends modified with HDPE crystallize to the degree of stiffness necessary to allow the material to be effectively granulated. Examples 47 to 54 In Example 47 (for comparison), a molded film sample of Amoco 10-6711 molded film grade polypropylene (MFR of 7.5 grams per 10 minutes) was prepared according to the procedure used in Examples 4 to 7. In this Example, the cooling water for the molding rolls during the preparation of the film was maintained at 40 ° C. In Example 48, a film was prepared in a manner identical to Example 47 except that 6 percent of the basic mixture of Example 44 was added to the Amoco PP 10-6711. In Example 49, a film molded identically to the two previous Examples was prepared with the exception that 6 percent of the base mix material of Example 45 was added to the polypropylene.

In Example 50, a molded film was produced in the same manner as the three previous examples with the exception that 6 percent of the basic mixture of Example 46 was added. In Examples 51 to 54 the films of Molded polypropylene was produced in an identical manner to the films of Examples 47 to 50 with the exception that ESCORENE 4292 was the grade of polypropylene used. The composition and tension properties for these film samples are listed in the table below.

Example Additive Type of PP Caliber of% of Film RR1139 HDPE (ml) (%) 47 - Amoco 1.5 (comp.) 10-6711 48 6%,. 44 1.5 2.4 1.2 49 6%. . 45 1.5 2.4 2.4 50 6%. . 46 1.5 1.8 51 -. 51 - Escorene 1.5 (comp.) 4292 1.5 52 6%,. 44 1.6 2.4 1.2 53 6%. . 45 1.5 2.4 2.4 54 6%. . 46 1.5 1.8 (Continued) Example Turbidity / Modulus Limit Elastic Luster (K kg / cm2) (K kg / cm2) (%) MD / TD MD / TD 47 4.3 / 76 7.59 / 7.73 .198 / .143 (comp.) 48 5.4 / 78 8.58 / 8.58 .224 / .226 49 4.4 / 78 10.33 / 11.18 .270 / .285 50 6.1 / 77 7.73 / 8-08 .211 / .213 51 3.6 / 73 7.32 / 6.96 .197 / .196 (comp.) 52 2.5 / 85 9.07 / 9.56 .238 / .240 53 2.7 / 83 8.30 / 9.42 .230 / .283 54 3.0 / 76 9.42 / 9.07 .266 / .255 In Amoco 10-6711 quality molded film polypropylene, the basic blend of Example 45 that was added in an equal amount of the REGALREZ 1139 hydrocarbon resin and the ALATHON H6611 HDPE to the molded PP film composition, was very effective to increase the rigidity of the film. In the ESCORENE 4292 polymer of low MFR, the basic mixture of Example 46, which contains HDPE H6611 but not hydrocarbon resin, was effective as the basic mixtures [REGALREZ 1139 + HDPE] to increase the modulus of the molded PP film . In these and all the above Examples the hydrocarbon resin and the HDPE were mixed in the polypropylene polymer during extrusion of the polymer in the process of molding films. To achieve the desired effect on the mechanical properties, both the hydrocarbon resin and HDPE must be properly dispersed in the base mix and there must be a satisfactory viscosity match between the base mix and the polypropylene polymer to allow the components of the base mix they are satisfactorily dispersed in the polypropylene polymer during the extrusion process of the film. Due to this reason, the molecular weight or MFR of the HDPE polymer is an important factor as is the MFR of the basic mixture [Hydrocarbon Resin * HDPE]. Comparing the Examples in the above table it will be noted that adding the basic mixture containing the HDPE H6111 without the hydrocarbon resin REGALREZ 1139 was more effective in increasing the stiffness of the ESCORENE 4292 polymer of lower MFR (Example 54) than the same basic mixture in the highest MFR of the Amoco polymer (Example 50). In the higher MFR Amoco polymer, the base mix compositions containing both hydrocarbon resin REGALREZ 1139 and HDPE were very effective in increasing stiffness (Examples 48 and 49), the basic mixture containing HDPE H6611 without the resin of hydrocarbon REGALREZ 1139 being only marginally effective (Example 50). In these Examples, the hydrocarbon resin greatly increased the MFR of the basic mixture formulation. This effect is important because an important factor in the final efficiency of the basic mixture is the appropriate viscosity matching between the base mix and the polypropylene polymer being modified which affects the final distribution of the additive in the film. The improved stiffness of molded PP films modified with low HDPE levels can result from faster crystallization HDPE while accelerating the crystallization rate of PP, in the modified formulation. When the molded film is produced, the cooling rate is very fast and the polymer can be rapidly cooled to a temperature low enough to prevent further crystallization before the desired level of crystallinity is developed. The faster crystallization results in a higher level of crystallinity and a higher modulus in the final molded PP film. The crystallization properties of the modified polypropylene formulations with the basic blends [Hydrocarbon Resin + HDPE] of this invention can be measured by differential scanning calorimetry (DSC). Several modified PP formulations were analyzed by DSC where the materials were cooled from melting temperatures to room temperature at a rate of 25 ° C per minute while the heat of crystallization and the temperature of maximum crystallization were measured. The crystallization properties of various formulations of PP modified with the HDPE ALATHON H6611 or without the additional hydrocarbon resin REGALREZ 1139, are listed in the table below.

Example Content Type Polypropylene REGALREZ 1139 HDPE (%) 47 Amoco 10-6711 49"" 2.4 2.4% 50"" - 1.8% 51 Escorene 4292 53"" 2.4 2.4% 54"" - 1.8% [Continued] Example Crystallization Heat Maximum Temperature (Joules / gram) of Crystallization (° C) 47 88.8 107.6 49 90.0 112.1 50 91.6 111.4 51 76.6 108.0 53 82.0 112.9 54 82.6 112.1 Normally, adding the hydrocarbon resin to the polypropylene reduces the maximum crystallization temperature and reduces the heat of crystallization by the same percentage in amount as the percentage of the amorphous resin added. In the Examples listed in the above table, formulations modified with hydrocarbon resin containing HDPE ALATHON H661 exhibited both a higher crystallization heat and a higher maximum crystallization temperature. Also, polypropylene formulations modified with only HDPE, H6611 exhibited the same effect. This effect can facilitate the development of higher levels of crystallinity in the case of PP films where the final crystallization level is strongly influenced by the rapid cooling that occurs during the film molding process.

Examples 55 to 58 In Example 55, a molded Polypropylene film of HD642H polypropylene, a molded film polymer grade manufactured by Borealis, (Copenhagen, Denmark) was prepared. The film was molded according to the procedure of Example 4 wherein the polymer was extruded into a cooling roller having a surface temperature of 50 ° C and the molding speeds were adjusted to produce a nominally molded film with a thickness of .0381 millimeter. In Example 56 a film was produced in a manner similar to Example 55 with the exception that the polymer feed contained 7 percent of the hydrocarbon resin concentrate REGALREZ 1139 / polypropylene, which was produced according to Example IB with the exception of that the concentration of REGALREZ 1139 in the mixture was reduced from 50 percent to 40 percent. In Example 57 a molded PP film identical to that of the two previous Examples was produced with the exception that 7 percent of the basic mixture of Example 44 was mixed with the polymer Borealis. In Example 58 a similar film was produced. wherein 7 percent of the basic mixture of Example 45 was mixed with the polymer Borealis. Tension properties and barrier properties were measured for these molded films. The composition of each film and its corresponding properties are listed in the table below for comparison purposes.

Example 55 Example 56 PP BOREALIS HD642H 100 97.2 Resin REGALREZ 1139 - 2.8 HDPE ALATHON H6611 Type of MB - Ex IB Stress Module, K kg / cm2, MD / TD 7.96 / 7.88 9.20 / 9.20 Elastic Limit, K kg / cm2, MD / TD .224 / .223 .237 / .234 Turbidity (%) 9.4 6.6 Luster 45 ° (% ) 58 66 Steam Transmission 9.86 9.08 Humidity (gr-.0245 mm / m-day 38 ° C, 90% RH Permeability of 02 8840 8630 at 23 ° C (ce-, 0254 mm / m2-day atmosphere) (Continuation Example 57 Example 58 PP BOREALIS HD642H 95.8 94.4 Resin REGALRESS 1139 2.8 2.8 HDPE ALATHON H6611 1.4 2.8 Type MB Ex. 44 Ex. Four. Five Voltage Module, K kg / cm2, MD / TD 10.66 / 10.95 11.24 / 11.61 Elastic Limit, K kg / cm2, MD / TD .278 / .296 .286 / .297 Turbidity (%) 5.1 4.4 Luster 45 ° (%) 70 73 Steam Transmission 7.10 6.77 Humidity (gr / .0245 mm / m2-day 38 ° C, 90% RH Permeability of 02 6700 6730 at 23 ° C (ce-.0254 mm / m -day-atmosphere) Examples 57 and 58 produced with hydrocarbon resin base mixture compounds containing HDPE further exhibited considerably higher tensile modulus and yield strength than for the polypropylene film which does not contain added hydrocarbon resin, and also considerably higher than the values for the film that contains 2.8 percent of REGALREZ 1139 but does not contain HDPE. Likewise, the films wherein HDPE was incorporated together with the REGALREZ 1139 using basic blends of Examples 44 and 45 exhibited considerably better oxygen and moisture barrier properties than the comparison films that do not contain HDPE. The novel formulations of this invention provide a means to improve the barrier properties of polypropylene films. Although the invention has been described in connection with certain preferred embodiments so that aspects thereof are better understood and appreciated, it is not intended to limit the invention to these specific embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents that may be included within the scope of the invention as defined by the appended claims.

Claims (26)

CLAIMS:

1. A process for producing a polyolefin article comprising providing a base mixture consisting of 10 percent to 90 percent by weight of high density polyethylene and at least one member selected from the group consisting of polyolefin and hydrocarbon resin; mix the basic mixture with polyolefin to form a polyolefin mixture; and extruding the mixture to form a polyolefin article.

2. A process according to claim 1, wherein the polyolefin in the basic mixture is present in a concentration of up to 85 percent by weight of the total basic mixture.

3. A process according to claim 1 or 2, wherein the polyolefin in the basic mixture comprises a polymer consisting of mono-alpha olefin monomers containing from 2 to 8 carbon atoms.

4. A process according to claim 1, 2 or 3, wherein the concentration of the high density polyethylene in the basic mixture never exceeds 40 weight percent of the total basic mixture unless the weight ratio of the hydrocarbon resin to high density polyethylene in. the basic mixture is at least 0.5: 1.

5. A process according to any of the preceding claims, wherein the concentration of the high density polyethylene in the basic mixture never exceeds 50 weight percent of the total basic mixture unless the weight ratio of the hydrocarbon resin to the high density polyethylene of the basic mixture is at least 0.5: 1.

6. A process according to any of the preceding claims, wherein the concentration of the high density polyethylene in a basic mixture never exceeds 60 weight percent of the total basic mixture unless the weight ratio of the hydrocarbon resin to high density polyethylene in the basic mixture is at least 0.5: 1.

A process according to any of the preceding claims, wherein the base mixture comprises hydrocarbon resin and the hydrocarbon resin and the high density polyethylene are present in a relative weight ratio between 0: 1 to 10: 1 in the basic mixture.

8. A process according to any of the preceding claims, wherein the basic mixture is granulated before being mixed with the olefin to form the mixture.

9. A process according to claims 1, 2, 3, 4, 5, 6 or 7, wherein the basic mixture is melt-mixed and granulated before being mixed with the polyolefin to form the mixture.

A process according to any of the preceding claims, wherein the basic mixture comprises polyolefin and the polyolefin in the basic mixture consists of alpha-olefin monomers containing from 2 to 8 carbon atoms, as long as the polymers of ethylene have a density of less than 0.930 gram per cubic centimeter.

11. A process according to any of the preceding claims, wherein the basic mixture comprises polyolefin and the polyolefin of the basic mixture is selected from the group consisting of polypropylene and polypropylene polymers with up to 20 weight percent of monomers that they are selected from the group consisting of ethylene and mono-alpha-olefin of 4 to 8 carbon atoms.

12. A process according to any of the preceding claims, wherein the polyolefin blend comprises from 2 percent to 25 percent by weight of the basic mixture.

13. A process according to any of the foregoing claims, wherein the polyolefin blend comprises from 4 percent to 10 percent by weight of the basic mixture.

A process according to any of the preceding claims, wherein the polyolefin blend comprises from 0.3 percent to 4.0 percent by weight of high density polyethylene and from 0 percent and weight to 5 percent by weight of hydrocarbon resin.

15. A process according to any of the preceding claims, where high density polyethylene has a density greater than 0.935 gram per cubic centimeter.

16. A process according to any of the preceding claims, wherein the high density polyethylene has a density greater than 0.950 gram per cubic centimeter.

17. A process according to any of the preceding claims, wherein the high density polyethylene has a density greater than 0.960 gram per cubic centimeter.

18. A process according to any of the preceding claims, wherein the basic mixture comprises a hydrocarbon resin, and the hydrocarbon resin is an aliphatic compatible resin with a number average molecular weight of 10,000 or less.

19. A process according to any of the preceding claims, wherein the basic mixture comprises a hydrocarbon resin and the hydrocarbon resin is a compatible aliphatic resin having an odorless mineral alcohol cloudiness (LMS) temperature of less than 0 ° C.

20. A process according to any of the preceding claims, wherein the basic mixture comprises a hydrocarbon resin and the hydrocarbon resin is a compound aliphatic resin having a cloudless odorless mineral alcohol (OMS) temperature of less than -40 ° C.

21. A process according to any of the preceding claims, wherein the basic mixture comprises a hydrocarbon resin and the hydrocarbon resin is a compatible aliphatic resin having a ring and ball softening temperature of 100 ° C or higher .

22. A process according to any of the preceding claims, wherein the basic mixture comprises a hydrocarbon resin and a high density polyethylene of a weight ratio of hydrocarbon resin to polyethylene at a high density of 0.5: 1 to 4. :1.

23. A process according to any of the preceding claims, wherein the polyolefin blend comprises from 2 percent to 3.5 weight percent hydrocarbon resin.

24. A basic mixture used in the process of any of the foregoing claims.

25. A polyolefin article produced according to the method of any of the foregoing claims.

26. The polyolefin article according to claim 25, wherein the article is a film.