MXPA99010683A - Polylactide coated paper - Google Patents

Abstract

A coated paper product including a paper layer and a polymer layer, wherein the polymer layer includes a polylactide polymer composition having a ratio of Mz to Mn of greater than about 6. The polymer composition, when melted, exhibits a die swell of greater than about 1.25 for a melt flow index of greater than about 2. Polymer lactide compositions, methods of manufacturing the polymer composition and the coatedpaper product, and articles produced therefrom are also described.

Description

PAPER COATED WITH POLYLACTIDE Field of the Invention The present invention concerns the technology of paper coating. This concerns general techniques, methods and materials that relate to paper coating with a biodegradable polymer, especially a biodegradable polymer composition, and articles made from coated paper.

Background of the Invention In recent years, attention has been focused on preferably degradable polymers. Most attention focused on polymers include, as monomer units within these, the result of lactic acid or lactic acid polymerization. Attention is focused, for example, on Patents North American Nos. 5,142,023 by Gruber et al; ,338,822 by Gruber et al; 5,475,080 by Gruber et al; 5,359,026 by Gruber et al; and 5,549,095 REF .: 32097 by Gruber et al; the full disclosure of these is incorporated here as a reference. It is noted that US Pat. Nos. 5,142,023; 5,338,822; 5,475,080; 5,359,026; and 5,594,095 are owners of Cargill Incorporated, of Minneapolis, Minnesota. Cargill Incorporated is the signatory of the present invention as well.

Other published documents relate to lactic acid or lactide polymers include: International Application No. WO 94/06856 by Sinclair et al, published March 31, 1994; International Application No. WO 92/04413 by Sinclair et al, published March 19, 1992; International Application No. WO 90/01521 by Sinclair et al, published February 22, 1990.

Paper coated with polymer or wax coatings is desirable because it can increase the strength of the stacked paper, impart water resistance, improve gloss, and / or improve the barrier properties. Polypropylene is a common polymer used in paper coating processes. See Film Manual, TAPPI Press, 1992, ISBN 0-89852-250-1 In view of the decrease in cellulosic fiber in the last decade, removing pulp from paper and accelerating the rejection of the cellulose fiber recovered in the process of pulp removal. A typical pulp removal process involves mechanical agitation of the paper. Frequently the pulp removal environment involves water, heat, or other severe conditions such as acid or alkaline solutions. A problem that occurs with the removal of the pulp in the coated paper is the disposal or recycling of the coating which is released during the process of pulp removal. In addition, papers coated with certain polymers, such as polyethylene, are not easily removed from the pulp since polyethylene typically does not break under the conditions of the pulp removal process.

Coatings have been developed which are represented as they can be "Removed the pulp". There are materials that supposedly have adequate properties as a paper coating, and when they are exposed to pulp removal conditions, they dissolve or disperse. In a solution or dispersion, it is claimed that these materials will stop through screens or other filtering stages and pass with the waste water before the pulp removal step. Although these coatings have been widely used, several problems have been encountered with their use. Frequently the coatings are not clear or shiny. Some coatings may also be inappropriately sensitive to water.

Disposal is the main problem associated with coatings that can be removed from the pulp and those that can not be removed. For coatings that are recovered during the pulp removal process, there is no value in recovering the material if it should be disposed in a landfill. The coatings that pass through filters and sieves in the process of pulp removal, these materials In the end, wastewater may have a problem for wastewater treatment plants.

Polylactide polymers have been used to coat paper products. See U.S. Patent No. 5,475,080. Polylactide polymers are advantageous because, once they are separated from the paper, they can be composted. Alternatively, all the coated paper product can be composted. In order to meet the projected needs for biodegradable packaging materials, others have strived to optimize systems that process lactic acid. (US Patent No. 5, 142, 023) by Gruber et al, discloses a continuous process for the manufacture of lactic polymers with optical purity from lactic acid having adequate physical properties to replace the current petrochemical-based polymers.

Generally, polymer manufacturers use processes such as those that are exposed by Gruber et al, will convert the raw material of monomers into polymers, beds, resins or other granulated or powdered products. The polymer is these forms are sold to end users who convert, for example, extruded, melt-molded, molded films, blown films, thermoforming, injection molding or weaving polymer fibers at elevated temperatures to form useful articles. The above processes collectively refer to fusion processing. Polymers produced by processes such as described by Gruber et al, which are sold commercially as granules, resins, powders or other solid unfinished forms are generally collectively referred to as polymer resins.

Brief Description of the Invention A coated paper is provided by the present invention. The product of the coated paper includes a paper layer and a polymer layer. The polymer layer comprises a polylactide polymer composition having a ratio of Mz to Mn greater than about 6. In a preferred embodiment, the polylactide polymer is a peroxide-modified polylactide polymer prepared by mixing the polylactide polymer with an alkyl peroxide. The polymer layer can be prepared from the molten polylactide polymer composition by exhibiting die dilation greater than 1.25 for a melt flow rate greater than about 2.

A method for coating paper is provided by the present invention. The method includes the steps of: (a) providing the polylactide polymer containing granules having a crystallinity greater than about 10 J / g; (b) melting the granules to provide the composition of the molten polylactide polymer having a die expansion greater than about 1.25 for a melt flow rate greater than about 2; and (c) extruding the molten polylactide polymer onto a substrate to provide a coated substrate. It should be understood that the alternative methods of coated paper are exposed additionally, including, proximity or coating with slot machines.

The invention is further directed to a polylactide polymer composition and methods for the preparation of the polylactide polymer composition. Generally, the composition of the polylactide polymer can be referred to as a "polylactide grade coating" because it can be processed in conventional paper coating equipment normally used to coat the paper with polyethylene. A preferred method for preparing the coating grade polylactide is by modification with linear polylactide peroxide or polylactide with modified viscosity. A preferred method of characterizing polymer grade polylactide is a polymeric composition which has a ratio of Mz to Mn greater than about 6, and which, when melted, exhibits a die expansion greater than about 1.4 for an index of melt flow greater than about 2.

Articles of manufacture that incorporate the coated paper product are also part of this invention. Articles of manufacture include boxes, rates, plates, bowls, butter and margarine wraps, pet food containers or boxes, hamburger wrappers and wraps for meat pieces, wrapped food containers, containers for packaging liquids, including coated cartons and bags for liquids bulky An advantage of the coated paper product of the invention is that it can be used adjacent to the food because this can be GRAS. In addition, the polylactide polymer coating can exhibit desirable heat sealing properties that allow it to be used without adhesives. In addition, the coating can provide desirable resistance to grease and barrier properties.

Brief Description of the Drawings Figure 1 is a sectional cross-sectional view of a paper product coated with in accordance with the principles of the present invention; Figure 2 is a sectional cross-sectional view of an alternate embodiment of a coated paper product in accordance with the principles of the present invention; Figure 3 is a sectional cross-sectional view of an alternate embodiment of a coated paper product in accordance with the principles of the present invention; Figure 4 is a schematic representation of a preferred modification of the polymer the paper coating process in accordance with the principles of the present invention; Figure 5 is a schematic view of an extrusion coating process of the present invention; Figure 6 is a schematic view of a slot machine coating process of the present invention; Figure 7 is a graph showing the relationship between die dilation and melt flow index for polylactide polymer; Figure 8 is a graph showing the relationship between the neck of entry and the dilation in the die for polylactide polymer; Figure 9 is a graph showing the relationship between dilation in the die and Mz / Mn for polylactide polymer and; Figure 10 is a perspective view of a paper cup that includes a coating of the polylactide polymer according to the present invention.

Detailed description of the invention The present invention concerns the technology of paper coating and how it can be used to provide coated paper and desirable articles with coated paper. In particular, the present invention relates to the preparation and use of coated paper having a coating layer prepared with the polylactide polymer composition to provide desirable characteristics.

Applicants have found that by controlling the melt stability, melt elasticity, and melt viscosity of the polylactide polymer, commercial paper coating equipment can be adapted to coat paper with polylactide. A polylactide polymer composition that has been modified or adapted to be processed into commercial or conventional paper coating equipment can be referred to herein as "coating grade polylactide". It is understood that this phrase means to exclude generally the compositions of the linear polylactide polymer which can not easily be processed in commercial or conventional equipment for paper coating.

The concept of polylactide fusion stability has several facets including molecular weight degradation, lactide reformation, and yellowing. In general, techniques that include reducing the level of lactic acid or lactide in the polymer to lower equilibrium values, removing the catalyst or reducing the levels of the catalyst, and the introduction of catalyst deactivators contribute to • reduce the reformation of lactide. These techniques are described in U.S. Patent No. 5,475,080 at, in particle, columns 7-8 and 14-15, the disclosure of these locations is incorporated herein by reference. In addition, stabilizers can be introduced to reduce the formation of lactide and to reduce yellowing over time. It has been found that tartaric acid is useful for reducing lactide reformation, and phosphite stabilizers have been found useful in reducing yellowing over time. The polymer can be dried to help reduce the degradation of molecular weight during processing.

The melt elasticity refers to the running ability of the polylactide polymer composition in the commercial extrusion equipment for the coating which is capable of removing the polymer composition in thin coatings with an inlet neck at high speeds with high velocity. temperatures required for good adhesion to paper. The elasticity requirements of the melt in relation to the polyethylene coating operations are well known. See Michael, Raj S. "Influence of Molecular Weight Distribution on Low Density Polyethylene Coating Performance" Vol. 77, No. 6, Tappi Journal 1994, pages 188-192. It is believed that the elasticity of the melt in the composition of the polylactide polymer is related to the extent or degree of stretching of the chain. Preferred techniques for the improvement to entangle the molecular chain or interaction of the polylactide polymers are described in US Pat. No. 5,594,095, all of which is incorporated herein by reference.

The melt viscosity is a measure of the melting capacity of the polymer to flow under an applied force. In the context of the present invention, it is desired that the melt viscosity, as a measure of the melt flow index, be a value which allows the molten polymer to be melted. Adhere to the surface of the paper and which allows the amount of material premium processed at a certain time. Generally, when the melt viscosity is increased, the amount of raw material processed in a given time decreases because it increases the die pressure. In addition, increasing the melt viscosity tends to require the increase of polymer temperatures which tend to increase the degradation of the polylactide polymer.

The following discussion focuses on the paper coating process of the present invention; the processing characteristics that can be modified to provide a desirable commercial product; and in the characteristics of the desired commercial product. Attention then focuses on the materials that can be advantageously used to provide coating grade polylactide, and on the articles that can be manufactured from the coated paper product. 1. Paper Coating A) Coated Paper and Processes for Manufacturing Now referring to Figure 1, a coated paper product in accordance with the present invention is shown with reference numeral 10. The coated paper product 10 includes a paper substrate 12 having a first surface 14 and a second surface 16, and a coating layer 18 adhered to the first surface 14. The coating layer 18 is preferably a polylactide polymer composition. An alternate embodiment of the coated paper product of the invention is shown in Figure 2 with a reference number 10 '. The coated paper product 10 'includes paper substrate 12' having the first surface 14 'and the second surface 16', a first coating layer 18 'adhered to the first surface 14', and a second coating layer 20 '. adhered to the second surface 16 '. The first coating layer 18 'and the second coating layer 20' may be the same or different. Preferably, at least one of the coatings includes a polylactide polymer composition. In the situation where the first and second coating layer both are compositions of the polylactide polymer, it should be understood that both coatings may or may not have the same chemical and / or physical properties. An exemplary product that may require coating having different properties is a coated paper product for use in the manufacture of the assortment of cups. As an article, it would be advantageous to provide the coating that will form the exterior of the cup with a high gloss and / or receiving surface for printing. The coating that would form the inner surface of the cup may desirably have a low coefficient of friction which allows the assembly of two thin layers and the disassembly of the cup without other cups.

Another alternate embodiment of the coated paper product of the invention is shown in Figure 3 as a reference 10 '. The coated paper product 10"includes the paper substrate 12" having the surface 14"and the second surface 16". The two layers are then coated in the first surface 14 ''. These layers are the first layer 13"and the second layer 18". Similar to the situation in Figure 2, the two layers may be the same or different. In the situation where these two are polylactide polymer compositions, it should be understood that both coatings may have different chemical and / or physical properties. For example, it may be advantageous to provide a layer 13"with a size of coating to improve adhesion on the first surface 14". The coating 18"may then be applied as a finishing surface. For example, the layer 13"may include polylactide with relatively low molecular weight to provide better adhesion on the first surface 14". The coating 18"may include a higher molecular weight polylactide composition to provide the desired final texture. Alternatively, the layer 13"may be used to provide additional barrier properties. It should be understood that it is appreciated that the layer 13"does not need to include a polylactide polymer this can be provided from non-lactide material to provide desired properties such co or barrier properties and / or adhesion between the layers.

It is expected that the first layer 13"and the second layer 18" will be applied sequentially or at the same time by coextrusion. The techniques for the coextrusion of polylactide are described in detail in the Series of the North American Patents Nos. 08 / 535,706, registered on September 28, 1995, and 08 / 642,329, registered on May 3, 1996. All the exhibitions of these two patent applications are incorporated herein by reference.

Although the invention is described in detail with reference to coated paper products, it should be appreciated that the coated paper product is a type of multilayer structure and that the invention may be characterized more broadly as a multilayer construction or structure. Furthermore, it should be understood that the multilayer structure of the invention does not need to incorporate paper as a substrate. That is, the multilayer structure of the invention can include a substrate in place of paper on which the composition of the polylactide polymer can be applied. Since a preferred embodiment of the invention is described with reference to paper as the substrate, the concept of the invention can be applied to substrates instead of paper, such as plates and other polymer films, which would be appreciated by one skilled in the art. the art.

In most applications where continuous coating is desired, it is expected that • the coating thickness will be between approximately 0.1 thousand and approximately 2 thousand. The minimum thickness of the coating is generally limited by the capacity to provide a continuous coating without holes or small holes. In most applications where polymer processing of polylactide is expected, a minimum thickness will be approximately 0. ~ 1 mil. The upper limit in the thickness of the coating is generally determined by the conservation of the material. That is, this is not usually necessary to use more necessary material for a given application. In the case of p ir-? < .rü _. a surface with barrier properties, It is generally desired to provide a surface thickness to maintain the barrier properties. Preferably, the thickness of a coating with polylactide polymer will be between about 0.3 mil. And about 1.2 thousand, and more preferably between about 0.5 thousand and 1 thousand.

It is generally the purpose of this invention to provide for the processing of the polylactide polymer on paper using readily available paper coating equipment. It is understood that most paper coating equipment is designed for the application of polymers, such as, low density polyethylene on paper. With a very small, if any modification, standard equipment for paper coating can be adapted to process the composition of the polylactide polymer of the invention on paper. In contrast, linear polylactide tends to be unsuitable for processing in conventional extrusion coating equipment without extensive modifications.

One aspect of the invention is the modification of linear polylactide to provide a polylactide composition that can be processed in conventional paper coating equipment. Thus, by adapting the composition of the polylactide polymer, and / or controlling parameters that control processing, the composition of the polylactide can be called "polylactide grade coating" and can be processed through conventional paper coating equipment. Modifications to the equipment or processing conditions which may be useful include modifying the screw extruder to provide lower compression to provide a greater amount of raw material processed in a certain time at an energy level in the die, and by shortening the breathing space between the outer punch and the paper to reduce the cooling effects of the ambient air. They are described in more detail Then techniques to modify conventional equipment for paper coating.

It is expected that unmodified linear polylactide can be processed in the paper using current coating equipment. The current coating equipment, however, is less conventional than the processing equipment for conventional extrusion coating, and does not provide the raw material processing levels at a desired time for various commercial paper coating applications. Since rheology can not be a problem for unmodified linear polylactide, melt stability may be the remaining problem in current coating processes.

The paper coating equipment can be specially prepared to coat the paper with polylactide polymer composition which takes into account various properties of the polylactide polymer composition as discussed above. It is expected, however, that the equipment specially designed for the Polylactide polymer composition processing will result in greater capital expenditure. It is expected that the market for paper coated with polylactide polymer will continue to develop, the equipment will be designed for the handling of polylactide polymer. Meanwhile, however, one advantage of the present invention is the ability to use conventional or standard paper coating equipment, typically used with polyethylene, to coat the paper with the composition of the polylactide polymer.

The paper coating generally involves several processing conditions in particular. The reason for this is that the composition should be fluid even if the surface of the paper is moistened, and adheres to the surface of the paper. In addition, commercial processing equipment such as extrusion coating equipment generally requires a large amount of polymer processed raw material in a certain time to coat the paper at high speeds. In order to maintain a large amount of raw material polymer processed over a period of time, the polymer must flow through a relatively narrow opening defined by the lips of the die. High temperatures are used to reduce the viscosity of the melt to provide a sufficient amount of polymer raw material processed in a certain time.

In addition, it is desired that the film be as thin as possible by providing a continuous coating on the paper. In order to ensure that the composition of the polymer is sufficiently fluid, the composition must be heated to an excess temperature which is generally required for applications such as fiber formation, film formation, and injection molding.

Processes for paper coating generally require very wide dies. The reason for this is that the die is usually wide although the wider paper is coated process is designed for the coating. In different applications the dies as wide as five feet in order to coat a paper with width of three feet. When it is desired to provide a narrow coating of an established die, the end of the die can be blocked. This forces the molten polymer composition to pass through the restricted aperture of the die. As a result, the molten polymer can remain in the die for a long period of time. In particular, eddies or certain circulation patterns may occur at the end of the die near the locking region, which tends to increase the average time the polymer remains in the die which increases the severity of the processing conditions. It is an advantage of this invention that a polylactide polymer composition can be provided with sufficient degradation stability during the processing conditions where the end of the die is blocked.

Extrusion coating and lining by approximation are two very common methods for coating paper. Both methods can be done by applying a composition of the polylactide polymer to a substrate according to the present invention. In general, extrusion coating includes different types of paper-wrapping processes that use an extruder to force the polymer through a die and includes, for example, the coating curtain. Coating by approximation generally refers to applications that provide a very close die in contact with the substrate. The coating resin is typically supplied with a fusion pump or with a combination of an extruder / fusion pump. In general, the approximate coating is used for the application of pressure sensitive adhesives on a substrate.

Now with reference to Figure 4, a diagram showing a total manufacturing process for producing coated paper according to the present invention is provided. The diagram shows the polymer grade polylactide coating with reference to the number 112 which can be fed into the system paper coating 114 for coating the paper. The grade-coated polylactide polymer 112 possesses the desired properties of melt stability and melt elasticity to be processed in a commercial paper coating equipment. The grade polylactide polymer coating 112 may be in the form of granules for convenient storage and transportation. The paper coating system 114 includes the processes of extrusion coating and / or approximation coating. The polylactide polymer 112 must have the chemical and physical characteristics identified by the invention for coating paper in conventional paper coating equipment. The coated paper 116 leaving the paper coating system 114 is generally in the form of large sheets or rolls which can then be sent to the place 118 for storing or the subsequent processing into articles of manufacture. The articles of manufacture are expected to include fees, plates, bowls, butter / margarine wraps, boxes and containers for animal feed, multilayer paper sacks, bags for storing cut grass, hamburger and meat wraps, food-bending containers, liquid-packaging containers, including folded cartons or bags for liquids, food containers where fat resistance and / or barrier properties are desired, and containers for food where recognized materials such as GRAS are desired. It is expected that the modifiers (paper-coating companies) will buy the polylactide polymer grade coating 112 in a form that has been modified to provide the features and properties described in this application. As described in more detail below, it is possible to modify certain types of linear polylactide to provide the characteristics and properties required by the coating grade polylactide. For example, you can not start with 100 linear polylactide available from Cargill Incorporated of Minneapolis Minnesota under the name of resin YOU , EcoPLA Alternatively, the commercially available resin may be a resin TM EcoPLA with modified viscosity. He linear or modified viscosity polylactide may also be modified to provide a polylactide polymer having the properties and characteristics required by the grade-impregnated polylactide polymer 112. Linear polylactide may be prepared according to that shown in US Patents Nos. 5,338,822 and 5,475,080 which are assigned to Cargill, Incorporated. The modified viscosity modified polylactide polymer can be prepared according to the teachings in U.S. Patent Nos. 5,359,026 and 5,594,095 assigned to Cargill, Incorporated. What is shown relates to the preparation of linear or modified viscosity polylactide provided in these Patents is incorporated herein by reference.

The linear polylactide or the polylactide with modified viscosity 100 is preferably in the form of granules which are suitable for storage or transport. The reference number 102 designates a storage place for polylactide 100, but it should be appreciated that it is not necessary to store the polylactide 100, and that this can be transported via line 104 to the polymer modification system 106. In the polymer modification system 106, the polymer 100 can be modified to provide a polymer having the desired melt elasticity as describes in the invention. This may include modification to rheology such as expansion by reaction with peroxide, branching by reaction with multifunctional chain coupling agents, and adjusting the molecular weight. The polymer modification system 106 may include the use of volatilization to remove residual lactide, and may include the addition of stabilizers, and a drying step to remove the water. The steps would preferably be made in an extension to provide stability to the melt. The modified polylactide 108 can be transported to a dryer 110 to remove the water.

The polymer 100 may be amorphous or semi-crystalline polymer. However, once it is processed through the modification system of polymer 106 and dryer 110, it is preferably a semicrystalline polymer. Applicants have found that the grade 12 polylactide coating is preferably a semi-crystalline polymer. As discussed in more detail below, it is desired to increase the crystallinity to process the polylactide polymer in conventional extrusion coating equipment. Alternatively, the grade polylactide polymer 112 may be amorphous. In the case of amorphous polylactide polymer, processes can be used that help to improve processing in conventional extrusion coating equipment. The grade polylactide polymer 112 can also be stored or fed directly into a paper coating system 114.

With reference to Figure 5, a diagram showing an extrusion coating process according to the present invention is provided. As shown, the polymer granules 28 can be introduced into the transport chamber 30 and fed into the extruder 32. The granules of polymer 28 may be referred to as a coating grade polylactide polymer having the desired characteristics of melt stability and melt elasticity identified in this application. The polymer granules 28 correspond to the modified polylactide polymer 112 provided in Figure 4. It is preferred that the granules fed to the transport chamber 30 are semi-crystalline to reduce adhesion.

It has been found that the polylactide polymer has a vitreous transition temperature of about 55-60 ° which originates in the granules adhesion under certain storage conditions or under the conditions of increased temperature in the transport chamber 30. Furthermore, it has been found that the amorphous polylactide tends to stick within the screw of the extruder 32 thereby increasing the energy requirements for operating the extruder 32. Accordingly, it is advantageous for the granules 28 to be semicrystalline in order to decrease the adherence incident during storage or in the transport chamber 30, and to decrease the adhesion in the screw of the extruder.

The granules 28 are melted in the extruder 32 and forced to pass through the hole 33 in the die 34 to provide a curtain 36 of molten polymer 38. The molten polymer 38 falls on a traveling paper substrate 40 and covers the substrate. Generally the molten polymer 38 can flow at a rate of 5 lb / hr per inch in width at 25 Ib / hr per inch in width, or greater, in order to cover paper traveling at a rate of about 30 ft / min at approximately 1500 ft / min.

The compression roller 42 and the cooling roller 44 are provided to improve the adhesion of the molten polymer 38 to a paper substrate 40. Thus, the pressure generated between the compression roller 42 and the cooling roller 44 forces the polymer melt 38. within the fibers of the paper substrate 40 to improve the adhesion the cooling roller 44 is in contact with the molten polymer 38 and must control the temperature in order to to prevent excessive heating of the roller that would cause the adhesion of the polymer to the roller.

The air gap 50 is the distance between the hole 33 provided in the die 34 and the contact point 48 where the molten polymer curtain 38 meets the paper substrate 40. When the curtain 36 is within this air space 50, both sides of curtain 36 are exposed to ambient air which promotes cooling. Accordingly, it is generally desired that the air space 50 be as small as possible.

It is generally expected that the paper 40 to be coated will be provided on a large roll 52, and once the paper 40 is coated and the coating is cooled to provide a coated paper product 46, it can then be collected on a roll 54 or , optionally, you can go directly to the manufacture of the item such as paper cup manufacturing. Along with the process, it is conventional to use tension rollers 56 in order to provide smooth flow through the extrusion coating system.

The effect of ambient air temperature on the molten polylactide polymer is important. In general, the processing of the polylactide polymer is restricted at high temperature. By this, it is understood that the temperature of the composition of the molten polylactide polymer should be high in order to ensure that the entire composition melts and remains fused when in contact with the paper substrate, but should not be so high that De-polymerization or degradation is induced in significant amounts. Thus, it is generally desirable to work as close to the melting temperature as possible. This means that the air gap should be as small as possible to reduce the extent of polymer degradation while in the die space. In more conventional polyethylene applications, the air gap is 7-10 inches, to promote oxidation. In the present invention reduce this air gap to 2-4 inches or less, to prevent excessive cooling of the polymer or the need to compensate for cooling when using high extrusion temperatures.

The cooling roller 44 may include a finishing surface 40 which may be smooth or textured to provide a finish for the coating 42 on the coated paper 46. It is an important feature of the present invention that the surface of the cooling roller may provide different finished in the coating of the polylactide polymer composition.

When it is desired to coat both sides of the paper 40, the first coating is applied as described below. A series of rollers can be used to rotate the paper so that the uncoated side with the surface facing up, and then the other extruder and die arrangement can be provided to place a second one on the paper 40. Although not shown in FIG. Figure 5, can be placed a dryer before the transport chamber 30 in order to ensure that the granules 28 entering the extruder 32 are sufficiently sjü < P? Q Now referring to Figure 6, a schematic view showing a conventional process of approaching or coating with a slot machine is provided. The apparatus 64 includes a first drive mechanism 66 which is capable of supporting a supply roll 68. The supply roll 68 carries a continuous strip of uncoated paper 70. The uncoated paper 70 contains two major surfaces 71 and 73. One or both of these major surfaces can be coated sequentially or simultaneously.

The first drive mechanism 66 supports a rotating shaft 72. The uncoated paper supply roll 68 is mounted on the shaft 72 which can be driven at a predetermined speed by the first drive mechanism 66 or rotatable by the force exerted on this. when removing uncoated paper 70.

The pickup roller 82 is coaxially mounted on the drive shaft 84 which is rotated by a second drive mechanism 86. The second drive mechanism 86 allows the coated paper 88 to be wound on the pickup roller 82 at a predetermined speed and under a proper tension.

The guide rollers 74 and 80 serve to align and guide this on the coating roller 76 and the cooling roller 78, before the receiving roller 82.

It has been found that a typical line speed using the apparatus 64 is from about 100 feet per minute (fpm) to about 1200 fpm. A more preferred line speed is between about 250 fpm to about 600 fpm the line speed can vary depending on the type of paper being coated, the particular composition of the liquid resin, the viscosity of the resin, the coating thickness, etc. .

The apparatus 64 also includes an approximate coating equipment 90 that contains a die of the slot machine 92. The slot machine die is angularly aligned with the coating roll 76 such that a small opening or compression may be present between the die of the slot machine 92 and the coating roll 76. This opening must be wide in order to allow uncoated paper 70 to pass therethrough. An opening or compression of less than about 0.05 inches (about 1.3 mm), and preferably less than about 0.01 inches (about 0.25 mm) is sufficient for most applications where the thickness of the coating to be applied is less than 1.0 mils. The exact size of the opening may depend on the thickness of the paper to be coated, the viscosity of the coating resin, the type of equipment one uses, the speed of the equipment, etc.

The polylactide resin, dry, semicrystalline, with modified rheology, in the form of granules 94 is loaded into the chamber of transport 95. The granules of the transport chamber 95 are fed by gravity to the extruder 96. The extruder 96 melts and heats and transports the polymer to the granules.

At the outlet of the throat 116 is a filter 118 that can remove any lumps or debris that may be present. At the outlet 108, the molten polylactide resin passes through the hose 120 to the approach coating equipment 90. In the coating equipment 90 the temperature of the molten resin is maintained and the resin is moved forward through the die. of the slot machine 92 at a predetermined pressure. The liquid resin is then supplied in the form of a liquid stream or sheet or film through the die of the slot machine 92. The thickness of the liquid resin applied to the uncoated paper 70 can vary by the size and configuration of the aperture formed in the die of the slot machine 92, as well as the internal pressure exerted on the liquid resin by the operation of the coating equipment 90. While the liquid resin it is applied to the uncoated paper 70, the paper 70 becomes coated as indicated by the number 88.

A uniform thickness of liquid resin should be deposited on the continuous strip of paper 70 as it travels through the opening formed between the slot of the slot machine 92 and the coating roll 76. The thickness of the coating can be adjusted by varying the speed of the paper in movement 70, the size of the opening formed in the slot of the slot machine 92, the internal pressure exerted on the liquid resin, the viscosity of the resin, the temperature of the resin, etc. One or more of these parameters can be adjusted for the precise control of the thickness of the coating that is applied to the coated paper 88.

After the molten resin is deposited on the passing paper 70 the coating is cooled as the paper 88 passes over the surface of the cooling roll 78. The resin is cooled to at least a partially solidified state, the resin is cooled to a solid consistency before it is wound on the receiving roller 82. One or more sequentially arranged cooling rollers can be used for a more efficient cooling of the resin 94. In Figure 6, only one cooling roller 78 is shown. Cooling roll 78 can be cooled with water or any other commercially available refrigerant type.

It should be noted that if one wishes to coat both major surfaces 71 and 73 of the paper strip 70 simultaneously, this is possible. This can be done by installing a second lining equipment of slot machines and a second liner roll adjacent to the first approach liner 90. Other variations may also make the apparatus 64 conform to the particular requirements of each. Alternatively, one can run the paper coated strip 88 back through the apparatus 64 and coat the uncoated surface 73 to obtain a paper strip that is coated on both major surfaces 71 and 73.

It should be appreciated that pneumatic forceps or air jets can be used to help control the polymer while it adheres to the paper. It is understood that the pneumatic grippers can cool the end of the polymer network which helps to stabilize the process. In addition, the polymer can overcoat the paper so that the edges of the forming bed can be cut without cutting the paper or substrate. It is expected that upon overcoating, a more uniform pressure is provided through the polymer that results in improved adhesion.

B) Characteristics of the Process and Polylactide Degree Coating Applicants have found that certain features must be maintained during the paper coating process in order to provide desirable results. Means to affect the processing characteristics include adjusting the chemistry of the polymer composition and adjusting the processing conditions during the process of paper coating. The techniques to provide the desired characteristics are discussed in more detail below. 1. Processing Equipment and Preferred Process Conditions The preferred method for coating paper is extrusion coating. As discussed previously, it is an advantage of the present invention that conventional polyethylene extrusion coating equipment can be used to coat the paper with polylactide grade coating. Conventional polyethylene paper coating equipment is described, for example, in Manual Extrusion Film, published in 1992 by TAPPI Press, ISBN: 0-89852-250-1, the entire disclosure of which is incorporated herein by reference. The desirable to cover the paper with polylactide grade coating can simply adopt the polyethylene extrusion coating equipment identified in the previous book and modify this, if necessary, in view of the following comments. It should be appreciated, that no Several modifications are required. It should be understood that the following conditions identified for processing the coating grade polylactide are preferred. The invention is not limited to the identified conditions.

The extruder designed to process polylactide can have a length / diameter (L / D) ratio of approximately 24: 1. Different extruders used to process polyethylene have an L / D ratio of approximately 30: 1 or greater. The longer screw in an extruder is needed to process polyethylene to ensure that all the polymer melts. The polylactide in contrast, melts relatively fast. With this a shorter screw length is preferred for processing the coating grade polylactide, the long screws normally associated with the polyethylene processing can be used.

The design of the screw for processing polyethylene generally provides a high compression ratio of approximately 4: 1. Contrast polylactide does not require a high compression ratio. Applicants have found that polylactide can be processed using a conventional polystyrene extrusion screw. Typical polystyrene extrusion screws are described in, for example, the "Manual Extrusion Film" published by TAPPI, 1992, as referred to above.

Extrusion coating systems for processing polyethylene generally provide an air gap of between 7 and 11 inches. This air space is relatively large in order to promote the oxidation of the polyethylene polymer. Polylactide, in contrast, does not require oxidation in the air space. Accordingly, it would be advantageous to reduce the die space of about 4 inches or less. It is particularly preferred to provide an air space of between 2 and 3 inches when processing grade polylactide coating. It should be understood that while a smaller air space is preferred for processing polylactide, the smaller length of air space is determined by the diameter of the cooling roller and / or the compression roller and the design of the equipment.

Coating. It is generally "preferred that the die space be as small as possible in order to minimize the cooling effect by ambient air prior to adhesion to the paper surface.

The space between the lips of the die refers to the space of the die. To process coating grade polylactide, it is preferred that the die space be between about 15 mils and about 30 mils. Preferably, the die space is between about 18 mils and about 25 mils. It is generally understood that a larger die space requires a higher attention ratio, in turn, causes instability and crease of the liner. If the die space is too small, the die pressure is increased, and the coating may be too thin or provide a poor addition.

Generally the cooling roller should run as hot as possible without sticking the polymer. This conserves energy and prevents condensation on the cooling roller. To process the coating grade polylactide, it is generally desired for the cooling water entering the cooling roll to have a temperature of about 80 ° F. Since it is difficult to measure the surface temperature of the cooling roller, the temperature is expected to be lower than the glass transition temperature of the coating grade polylactide. Generally, it is believed that the temperature of the cooling surface will be less than about 130 ° F.

When coating grade polylactide is processed in an extrusion coating process, it is generally desired that the compression pressure be between about 2 and 5 bar. This amount of pressure helps to provide the proper adhesion of the extruded polylactide in order to avoid excessive wear on the rollers.

The surface of the cooling roller can be modified to provide a desired texture in the coating. For example, a Highly polished chrome roller can provide a highly glossy finish. The highly glossy finish can be advantageous when it is desired to provide a finishing surface for receiving a print. A cooling roller having a rough surface can produce a matte finish which may be desirable to provide a coating surface having a lower coefficient of friction.

The majority of applications for processing grade polylactide coating through a die, it is expected that the width of the die can be any width commercially used in paper coating processes. Generally, this will correspond to a width of between 2 feet and 10 feet. Thus, it should be appreciated that because of the width of the die used in the extrusion coating processes, the coating grade polylactide must have sufficient melt stability and melt elasticity to flow properly through a die.

The conventional paper coating equipment for processing polyethylene frequently has some or all of the following equipment: a non-vented barrel; a general-purpose screw with L / D ratios of 24: 1 to 30: 1 and 3: 1 compression ratio; a cooling screw for the feeding section; a separator plate with 60-80 mesh screens for greater productivity and safety. It should be noted that the coating grade polylactide can be processed in conventional equipment. 2. Preferred Operating Conditions When coating grade polylactide is processed through the extrusion coating equipment, it is generally preferred to provide coating grade polylactide in semicrystalline form prior to melting. It is generally preferred that the crystallinity be greater than about 10 J / g, and more preferably greater than about 15 J / g. The applicants have found that the Amorphous polylactide tends to block during storage and transport. This means that the amorphous polylactic polymer granules tend to stick or agglomerate, particularly under hot conditions frequently found in warehouses in the southern United States. In addition, the amorphous polylactic polymer granules tend to melt in the transport chamber as a result of the heat generated in the extruder. Furthermore, applicants have found that the amorphous polylactide polymer tends to stick to the screw within a single screw extruder. As discussed above it is expected that the extruders used to process polylactide will be conventional polyethylene extruders having relatively large L / D ratios. It has been found that amorphous polylactide tends to stick to the screw in the extruders before it is fully melted. These problems can be minimized by providing semicrystalline polylactide.

Before the step of feeding the grade polylactide coating to the transport chamber for extrusion coating, it is generally preferred to further dry the polylactide using a conventional inline drying apparatus. The polymer is preferably transported from the dryer in line to the transport chamber without exposure to the environment. The polylactide grade coating is generally sensitive to moisture during the melt process, and increases the levels of moisture that have been found to contribute to molecular weight degradation. Semi-crystalline polylactide granules can advantageously be dried at temperatures of about 60-130 ° C, while amorphous polylactide granules should generally be dried below 60 ° C, this being the glass transition temperature.

The extruder that melts the polylactide grade coating preferably provides a melting temperature of between 480 ° F and about 560 ° F. It is generally desired that the temperature of the molten polylactide be high enough so that all of the polylactide melts and so that the curtain melted adhere to the surface of the paper. The higher temperature of the molten polylactide is restricted by considerations of melt strength and degradation. Because polylactide is sensitive to temperature, the temperature of the molten polylactide should not be so high to adversely affect the melting strength of the curtain or the degradation of the polymer. More preferably, the temperature of the molten polylactide should be between about 495 ° F and about 450 ° F. More preferably, the temperature of the molten polylactide in the extruder should be between about 500 ° F and 530 ° F.

The molten polymer is preferably supplied to the die with a quantity of processed raw material greater than about 5 lb / hr per inch of die width. More preferably with a quantity of raw material greater than about 10 Ib / hr per inch of die width. It has been found that lower amounts of raw material can be used processed to provide adherable coatings, but when used to provide thin coatings, it sometimes fails to provide one. Adequate adhesion of the coating to the paper substrate. It is believed that the lower amount of processed raw material results in better cooling of the molten curtain so that the thin films are not so hot to provide adequate adhesion. In general, the amount of raw material processed is determined to provide sufficient heat capacity to obtain the desired adhesion to the paper.

Generally, the speed of the process line for processing grade-grade polylactide in extrusion coating equipment runs between approximately "300 and approximately 2000 ft / min." More preferably, the line speed is between approximately 500 and approximately 1500 ft / min. It has been found that in conventional extrusion coating equipment for polyethylene, the coating thickness can be provided at these line speeds. of polylactide is between about 0.1 thousand and about 2 thousand. More preferably the thickness between about 0.3 mil and about 1.5 mil, and more preferably the thickness between about 0.5 mil and about 1.0 mil.

Fusion stability The polylactide polymers that can be used in the paper coating operations of the present invention are melt stable. By "melt-stable" it is generally understood that polylactide polymer, when subjected to fusion processing techniques, adequately maintains its physical properties and does not generate by-products in sufficient quantity to contaminate or cover the processing equipment. The melt-stable polylactide polymer exhibits reduced degradation and / or reduced lactide formation relative to known lactide polymers. It is understood that the degradation will occur during the fusion process. The requirements for composition and use of stabilizing agents as set forth herein it reduces the degree of this degradation to a point where physical barriers are not significantly affected by the melting process and contamination by impurities or degradation of by-products such as lactide does not occur. The melt-stable polymer must be processable by fission in fusion processing equipment such as commercially available equipment. In addition, the polymer will preferably retain adequate molecular weight and viscosity. The polymer preferably should have a sufficiently low viscosity at the temperature of the melting process so that the coating equipment can create an acceptable coating. The temperature at which this viscosity is sufficiently low will also preferably be lower than the temperature at which substantial degradation occurs. The stability of the polylactide polymers can generally be separated into three types. The formation stability of lactide refers to the resistance to depolymerization to form lactide, high processing temperatures and long processing times tend to cause the formation of lactide in the molten polymer. This is a problem because the lactide can be separated instantaneously, during polymer processing, causing fumes and contamination of the equipment. The presence of large amounts of lactide in the final product is undesirable because it affects the physical properties in the storage life. Molecular weight degradation is a problem because it affects viscosity and physical properties, such as tensile strength, performance, impact resistance, etc. It is important to control the molecular weight in a safe manner in order to maintain quality. Polylactide polymers are prone to yellow / brown color development due to prolonged exposure to heat. This is undesirable for several applications when a light color is desired.

Fusion elasticity In order to process the polylactide polymer in commercial extrusion coating equipment, the polylactide polymer must have good fusion elasticity. It is desired to extrude and stretch thin coatings of the polylactide polymer with a minimum inlet neck at high speeds with high temperatures required for good adhesion to paper. It is believed that the melt elasticity is related to the molecular interaction or interlacing of the polymer chain.

As discussed above, the polylactide grade coating includes the characteristics that allow it to be processed in conventional paper coating equipment typically designed to process polyethylene. Applicants have found that linear polylactide is generally not suitable for processing in non-conventional paper coating equipment. It is believed that the reason for this is that the linear polylactide does not possess the melt elasticity necessary to provide the amount of commercially acceptable processed raw material to acceptable levels at the neck entrance and the coating stability. The linear polylactide is generally characterized in that it is prepared by the open ring of lactide or by the direct condensation of lactic acid in the absence of multifunctional or branching initiators or binding agents. The linear polylactide will generally have a molecular weight characterized by a Flory-Schultz distribution (also known as the "most likely distribution"). This distribution is generally characterized by a polydispersity index (PDI) of less than about 2.2 (ideally about 2.0) and an M2 / Mn ratio of about 3.0. The more conventional linear polylactide polymers will have values somewhat close to these values of PDI and Mz / Mn. Some deviation is expected due to the variation in polymer processing, but it is also expected that the polymer will exhibit general characteristics of the linear polymer. This equates a low degree of chain binding and a low melt elasticity. Methods for increasing molecular interaction or chain binding are described in detail in U.S. Patent No. 5,594,095 in columns 4-28, this portion of the U.S. Patent.

No. 5,594,095 is incorporated herein by reference. Generally these methods involve the increase of molecular weight, the increase of the branching, or the increase of the bond.

It has been observed that the increase in molecular weight tends to increase the molecular bond and also increases the viscosity. If the viscosity becomes very high, the polymer will not be easily processable nor will it penetrate into the surface of the adhesion paper. Increasing the temperature to a level necessary to process linear polylactide is not practical because the melt elasticity is sacrificed and the extent of polymer degradation is increased.

To compensate for the appropriately contradictory properties of increasing the melt elasticity while maintaining the low viscosity, it is preferable to extend the molecular weight distribution. The extension of the molecular weight distribution (MWD) can be characterized by the polydispersity index (PDI, defined as Mw / Mn) or by the ratio Mz / Mn. In addition to increasing the MWD, the high viscosities resulting from the increase in the average molecular weight (Mw) can be compensated for by mixing low molecular weight polymer within the resin. It is believed that this can be done by adding thickening resins or low molecular weight fractions of polylactide.

Joining and branching are the preferred methods for increasing chain binding and thereby expanding the molecular weight distribution. The degree of entanglement of the chain is proportional to the type of branch or link of the chain. Branch long chains favors the entanglement of the chain on the branching of short chains. The desired degree of binding and / or branching can be obtained by modifying the total composition of the polymer or by adding a small amount (between about 3 percent and about 20 percent by weight of the composition) of the highly branched or interlaced polymer.

As discussed above, the molecular weight distribution can be used as an indirect indicator of melt elasticity. That is, a very broad molecular weight distribution generally provides desirable fusion elasticity. The melt elasticity can be directly known by measuring the expansion ratio in the die in the extrusion of a melt flow index instrument according to ASTM-D1238 with a die with a diameter of 0.0825 and carried out at 210 ° C. and 2.16 kg, and reported in grams of polymer for 10 minutes. Dilation in the die is a measure of the ratio of the diameter of the extrudate to the die. In the context of this invention, the property of "dilation in the die" is determined by cutting the strand of the polymer leaving the melt flow rate test when it is one inch long. The diameter of the strand is measured in at least three places and averaged. Generally this test is repeated 5 times to improve reproduction. A Newtonian fluid demonstrates expansion ratios of about 1.1 or less. While it is increases the elasticity increases the dilation in the die. Accordingly, it is desirable to provide polylactide polymer with a dilation in the die greater than about 1.25, and preferably greater than 1.3. more preferably, the dilation in the die for the polylactide according to the invention is greater than 1.4. by comparison, the dilation in the linear polylactide die is about 1.2 or less with a melt flow index of 8 or greater, and is about 1.4 or less for the melt flow index of 4 or greater, and it is estimated that is about 1.5 or less for the melt flow rate of two or more. This is shown by Figure 7.

The expansion ratio in the die to access the difference in melt elasticity between the polylactide and a commercial grade low density polyethylene used in the extrusion coating. Using an instrument to measure melt flow index at 210 ° C and 2.16 kg force, the expansion ratio for linear PLA is generally less than or equal to 1.1 while the expansion ratio of the LDPE may be 1.5 or greater. At the same time, linear PLA tends to provide a large entrance in the neck with poor stress characteristics.

The molten polymer should be provided with a melt viscosity that is sufficient to provide an operating pressure of the die and allow the desired adhesion of the molten polymer to the paper substrate. As discussed above, increasing the entanglement of the chain tends to improve the melt elasticity of the polylactide, this additionally tends to increase the melt viscosity, particularly if it is done by increasing the molecular weight. In a preferred process, the branching of a long chain induced by bonds (eg, by modification with peroxide) is used to increase chain entanglement without dramatically increasing the melt viscosity. The melt flow index (NFI), as written above, is a useful measure of viscosity. Generally a high MFI corresponds to a material with low viscosity and a low MFI corresponds to a material with high viscosity. The linear polylactide exhibits a strong correlation between the average molecular weight (M ") and MFI, with additional correlation between the residual lactide level and MFI. The long chain branching, as preferred in the present composition, causes a deviation from this relationship.

For extrusion coating, applicants have found that the MFI should preferably be within the range of about 2 to about 30. More preferably, the MFI should be in the range of about 8 to about 20, and more preferably in the range of approximately 12 to approximately 16.

Referring now to Figure 7 which shows the relationship between die dilation and melt flow index (MFI) for the polymer modified polylactide with epoxidized soybean oil and the same polymer after modification with peroxide. The data provided in Figure 7 were taken from Tables 2-4. It is expected that the polylactide polymer will exhibit die expansion values less than those exhibited by the modified polylactide polymer with epoxidized soybean oil. It should be appreciated that the large dilation can be obtained by the linear polylactic polymer but only with very low MFI values (of about 2 or less). For paper coating operations, it is desirable to provide a melt flow rate greater than about 1.2. in preferred compositions, the melt flow rate will be greater than about 2, and the die expansion values greater than about 1.3. even more preferably, the dilation in the die should be greater about 1.4. In general, the preferred compositions exhibit MFI values and die dilation greater than that shown in the line of the solid in Figure 7. Preferably, the compositions exhibit an MFI in excess of 10 and a dilation in the die in excess of 1.4. (more preferably 1.4).

The line of the solid shown in the graph of Figure 7 can be mathematically characterized as the dilation in the die equal to 1.6 less 0.05 times for the values of the melt flow index between 2 and 8; and the dilation in the die is equal to 1.2 for melt flow index values of 8 or greater. It should be understood that compositions exhibiting a melt flow index of less than 2 are generally not desirable for paper coating applications.

The reason for the difference in the width of the dies and the width of the paper is explained as a phenomenon known as "entrance neck". The neck of entry refers to the narrowing of the width of a film while it leaves a die. During certain operations of fusion processing, linear polymers such as linear polylactide exhibit certain undesirable flow properties, such as the inlet neck.

For example, if polylactide is extruded as a film on a mobile substrate, the Polylactide film that is directed onto the substrate will tend on the neck under the tensile forces caused by the moving substrate. In this phenomenon, the entrance neck causes problems when controlling the process and problems when maintaining the thickness of the film. Linear polymers such as linear polylactide also tend to exhibit hydrodynamic instability or stress resonance at large stress ratios. This resonance of tension can cause a periodic variation in a coating with and / or size for example, this can cause the breaking of the polymer network.

B) Characteristics of Paper Coated with Polylactide Paper products are frequently coated with polymeric or wax coatings in order to increase the strength of the stored paper, impart water resistance, improve gloss, and improve barrier properties. The applicants have found that the The use of the polylactide polymer composition for the stored paper provides several advantages. In particular, applicants found that the use of a polylactide polymer composition provides greater grease resistance compared to polyolefins. The grease resistance of the paper coated with the polylactide polymer composition according to the present invention provides higher grease strength, without penetration after 65 hours at 100 ° C, according to the ASTM F119 test method. In comparison, the paper coated with polyethylene shows penetration of the fat after 10 hours.

By providing a coated paper product having improved grease resistance, it should be readily appreciated that this type of product would be advantageous for use in wrapping products having a high fat content for example, the coated paper product could be used as a food wrap for meat and fish products, hamburgers, sandwiches, and cheese. In addition, the coated paper would be useful as a liner for the pet food, such as dog food, which tends to be high in fat, and in the form of containers with folds for food, containers for the packing of liquids, including folded cartons and boxes for liquids.

It has also been found that polylactide provides an effective barrier to flavor and aroma molecules, as exemplified by ethyl butyrate and d-limonene. A method for testing the aroma barrier has been described by J. C. Tou, D. C. Rulf, and P. T. DeLassus, in Analytical Chemistry, vol. 62_, p. 592-597 (1990). A great development was found for the polyolefins in the polylactide films. This property also improves its utility in the applications mentioned above. Polylactide has moderate steam water transmission speeds, which will be suitable for several applications. If a large barrier to water vapor is needed it is necessary that polymer layers can be provided.

Another advantage of the coated paper product of the invention is the ability to provide a coated paper product which can heat seal at a relatively low temperature. Due to the heat sealing properties, no adhesives need to be used when the composition of the polylactide polymer can serve as a sealing material. In a preferred coating, the polymer composition is amorphous, and can easily seal with heat at temperatures above the vitreous transition temperature of 55-60 ° C.

With reference to Figure 10 a rate 150 is shown manufactured with a coated paper product 52. The coated paper product 152 includes a stacked paper 154 and a coating composition of the polylactide polymer 156.

Rate 150 is manufactured by first supplying a large sheet of coated paper. A rate pattern of the large sheet is cut to provide the stacked sheet 152. The stacked sheet 152 is then rolled and heat sealed along the sealing edge with heat 158 so as to form the outer wall of the rate. He flange 160 is then formed by rolling the top end 162 of the rate and again, this flange 160 is sealed with heat. It is an advantage of the polylactide polymer composition that it can be heated to a relatively low temperature, such as a temperature less than about 70 ° C, in order to sufficiently melt the polylactide polymer composition so that it forms a bond. The bottom 164 of the rate 150 is formed by similar cutting of a pattern, and is sealed by heating at the lower end 166 of the rate 150.

Applicants found that the flexibility of the composition of the polylactide polymer coating can be maintained by adjusting the molecular weight. For example, by maintaining the average molecular weight above 80,000 and preferably above 120,000.

The coefficient of friction of the coated surface of the coated paper product of the invention can be adjusted to a desired level by the processing parameters. For example, at Adjust the texture of the cooling roller or when incorporating the sliding agents.

Applications where a coating having a low coefficient of friction are desired to include applications such as the interior of the rates of coated paper (to discourage), paper plates (at least one surface), and applicators (teles as applicators). tampons or suppositories).

It should be recognized that a high gloss finish, which may be desirable for various types of applications, would result primarily with a high coefficient of friction. An application where a high coefficient of friction may be desirable is in coated paper bags, where it is desired that bags can be stacked without slipping.

The coefficient of friction (COF) can be determined by following the ASTM D-1894 method. Polylactide with a high coefficient of friction will generally have a COF, for polymers that slip into polymers, greater than 0.6, preferably greater than 0.75. This is easily provided when using a smooth, highly glossy roller. A lower COF value, for articles coated with polylactide, will be less than 0.6, preferably less than 0.4, and more preferably in the range of 0.1-0.3. This is comparable with several polyethylene films.

The applicants found that the composition of the polylactide polymer, when coated on paper, provides good development of small holes. In general, preferred polylactide polymer compositions of the invention can be provided with a thickness of 0.4 mil and remain essentially free of small holes. By "essentially free of small holes", it is understood that the coated paper product will provide desirable barrier properties when used commercially.

The coating of the present invention exhibits a higher surface energy than typical polyethylene or polypropylene films. These hydrocarbon films have a surface energy in the range of -33 dynes / cm. This not only increases the costs associated with the production of the films, but the modification of the treatment will be diffuse in the film will produce an unsatisfactory stamping surface.

The surface energy of the substantially pure poly (lactide) films of the present invention is about 38 to 44 dynes / cm. This results in a surface with satisfactory stamping characteristics without surface modification however, in the preferred processing, a corona treatment is used to increase the surface energy, as much as 50 dynes / cm. Additionally, inks that are typically more difficult to apply on paper coatings, such as water-based inks, can be applied directly to poly (lactide). The techniques for corona treatment are described in Manual Extrusion Film, TAPPI Press, 1992, chapter 8, pages 129-150, incorporated herein by reference.

Products that can use the coated paper product include boxes, rates, plates, wraps for butter and margarine, pet food containers or boxes, hamburger wraps, multilayer bags, slip-proof bags, and meat wraps.

II Materials In general, preferred polymers that can be provided according to the present invention include at least one component, polylactide or polylactic acid (polylactide and polylactic acid refer to, collectively, herein as polylactide or PLA).

In general, the polymer nomenclature sometimes referred to as polymers in the base of the monomer from which the polymer is made, and in other examples characterizes the polymer based on the smaller repeating units found in the polymer. For example, the smallest repeat unit in polylactide is acid lactic acid (currently residues of lactic acid). However, in typical examples, commercial polylactide will be manufactured from the polymerization of lactide monomer, instead of lactic acid. The lactide monomer, of course, is a lactic acid diimer. Here the terms "polylactic acid", "polylactide", and "PLA" are intended to include within their scope both the polymers based on polylactic acid and polymers based on polylactide, with the terms used interchangeably. That is, the terms "polylactic acid", "polylactide", and "PLA" are not intended to be limited with respect to the manner in which the polymer is formed.

The term "polylactide-based" polymer or "polylactic acid-based" polymer means that it refers to polylactic acid or polylactide polymers, as well as copolymers of lactic acid or lactide, where the resulting polymer comprises at least 50%, weight , repeating units of the lactic acid residue or repeating units of the lactide residue. In this context, the term "repeat unit of Lactic acid residue "means that it refers to the following unit: In view of the above definition, it should be clear that polylactide can refer to both as a polymer containing residues of lactic acid and as a polymer containing residues of a lactide. Here the term "repeated unit of the lactic residue" refers to the following repeated unit: It should be noted that the repeated unit of the lactide residue can be obtained from L-lactide, D-lactide and meso-lactide. L-lactide is composed of two residual S-lactic acids; D-lactide is composed of two residual S-lactic acids and one residual R-lactic acid.

In addition, it should be understood that the term "PLA" is not intended to limit a composition to one containing only polylactide or polylactic acid as the polymer component as used herein, the term "PLA" converts compositions containing a polymer containing the units. of residual lactic acid described above with an amount of at least 50%, by weight, based on the total repeating units in the polymer. A PLA composition may include other components blended with the polymer containing at least 50%, by weight, of repeated units of lactic acid. In most applications, it is believed that the coating component containing polylactide will be the dominant material. Generally, it is expected that at least about 20% of the component will be comprised of a polylactide material. Preferably the component will include at least about 70% by weight of polylactide, and more preferably at least about 90% by weight of polylactide. It should be appreciated that the amount of polylactide present in a particular compound depends on the desired property that will be imparted to this component. In the case where the component is intended to be completely compostable, this is mainly that 100%, weight of the component will be polylactide and the additives can be composted.

A. PLA (Polylactic Acid or Polylactide) PLA-based polymers useful for conversion to coat materials according to the preferred techniques described herein are prepared from the polymerization of lactide or lactic acid. In some applications, the polymerization may be a copolymerization, with the lactide or lactic acid monomer copolymerized with another material.

In some examples, lactic acid or lactide can be first polymerized, with the resulting polymer mixture when reacting, for example copolymerized, with another material in order to provide some modifications, for example in relation to molecular weight or polydispersity.

In the context of the present invention, in reference to degradable polymers include polymers that can be given composting treatment. Compostable polymers are polymers that have at least a portion which will break and become part of a compost subject to physical, chemical, thermal and / or biological degradation in a solid waste composting facility or biogasification. As used in this application, a composting or biogasification facility has a specific environment that induces rapid or accelerated degradation. Generally, conditions that provide rapid or accelerated degradation, compared to storage or conditions of use, are referred to herein as composting conditions.

It should be appreciated that the polymers of the invention can be fully or partially compostable, depending on the amount of compostable material in the fibers. The compostable component of the polymer composition must be compostable and biodegradable during composting / biogasification, or in solid amended with compost, at a speed and / or grade comparable to known reference materials such as paper cellulose. Basically, this means that the components must be biodegradable within a time where. the products made of these, after using them, they can be recycled when composting and used as a compost. It should be understood that certain materials such as hydrocarbons and other polymeric resins including polyethylenes, polypropylenes, polyvinyls, polystyrenes, polyvinyl chloride resins, urea formaldehyde resins, polyethylene terephthalate resins, polybutylene terephthalate resins, and the like are not considered compostable. or biodegradable for purposes of this invention because these take long degradation when alone or in a compost environment. The speed and degree of biodegradation of the compostable materials are described in detail in the US Patent Series No. 08 / 642,329, which was registered with the United States Patent and Trademark Office on May 3, 1996, all the exposition of this is incorporated here as a reference.

Polymers containing lactic acid residues are particularly preferred for use in the present invention due to their hydrolysable and biodegradable nature. One theory of the degradation of the lactic acid residue polymer is that it can be degraded by hydrolysis with hydrolysable groups to lactic acid molecules that are subjected to enzymatic decomposition by a wide variety of microorganisms. It should be appreciated, however, that the precise mechanism of degradation is not a critical feature of the present invention. Rather, it is enough that one recognizes that the polymer which provides the similar rapid degradation towards natural end products that may be useful in the present invention. U.S. Patent No. 5,142,023 published by Gruber et al, on August 25, 1992, the disclosure of which is hereby incorporated by reference, generally discloses a continuous process for the manufacture of lactic acid polymers from lactic acid. The related processes for generating purified lactide and creating polymers with this are disclosed in U.S. Patent Nos. 5,247,058; 5,247,059; and 5,274,073 published by Gruber et al, the expositions of which are incorporated herein by reference. It should be appreciated that the polymers selected from the patents have the appropriate physical properties so that they can be used in the present invention. Generally, the polymers according to U.S. Patent No. 5,338,822 published by Gruber et al, on August 16, 1994 and U.S. Patent No. 08 / 279,732 filed July 27, 1994, which is incorporated herein by reference , can be used in the present invention. Polymers that contain lactic acid residues exemplified may be used as described in U.S. Patent Nos. 5,142,023; 5,274,059; 5,274,073; 5,258,488; 5,357,035; 5,338,822 and 5,359,026 by Gruber et al, and US Patents Series No. 08 / 110,424; 08 / 110,394; and 08 / 279,732, the expositions of which are incorporated herein by reference. The polylactide polymers that can be used in the invention are available under the trademark EcoPLA ™ by Cargill, Incorporated.

B. Advantageous Properties of Polylactide In the context of coating formation, it is desired to provide the polylactide polymer with a desirable melt flow index, molecular weight ranges, PDI, Mz / Mn, optical composition and melt stability.

To provide a coating that exhibits the desired properties of hardness and breaking strength, it is preferred that the polylactide polymer be provided with a molecular weight average between approximately 60,000 and 300,000. More preferably, an average molecular weight of between about 80,000 and about 275,000 is provided, and even more preferably between about 100,000 and about 250,000. It should be understood that the lower limit of the average molecular weight is determined with physical properties such as tensile strength. The upper limit of the average molecular weight is generally determined by consideration such as the ability to process the melt.

The melt flow index (MFI) is a useful indicator of the ability to process the melt. In the context of the present invention, the MFI values of measured following ASTM D1238-95 at 210 ° C and 2.16 kg. Preferred compositions of the invention exhibit an MFI between about 2 and about 30 and more preferably between about 8 and about 20, and more preferably between about 12 and about 16. The lower limit of the MFI value is restricted for considerations of viscosity and adhesion to the substrate.

The polydispersity index (PDI) of the polylactide polymer is generally a function of branching or entanglement. The linear polylactide will have a PDI, defined as the weight average molecular weight divided by the average molecular weight number, of about 2.0. Increasing the binding or crosslinking can be advantageously used to increase the PDI. Preferred compositions will have a PDI greater than 2.5 and more preferably above 2.9.

The linear polylactide is expected to have an Mz / Mn ratio of about 3. The preferred residence of the present invention, in contrast, will have an Mz / Mn ratio greater than about 6, more preferably greater than about 7, and more preferably higher. of about 8. As shown in Example 6 and Figures 8 and 9, the polylactide polymers exhibit higher values of Mz / Mn which provide better dilation in the die and reduced entrance neck. It should be appreciated that Mz / Mn values as high as 11 were observed in polylactide polymer compositions using the peroxide entanglement methods detailed in Example 6. These compositions are believed to be advantageous and even high values may be beneficial. .

The peroxide linkage is described in Examples 6-8 and in US Patent No. 5,594,095 is a preferred method for generating coating grade polylactide. The disclosure of U.S. Patent No. 5,594,095 in column 15, lines 21-59 is incorporated herein by reference. Other methods can also be used to generate coating grade polylactide, providing adequate dilation in the die obtaining the appropriate MFI.

It is believed that the entanglement with peroxide is spatially effective because the probability of reaction is proportional to the molecular weight of the polymer. The higher molecular weights are therefore preferably intertwined, causing a rapid increase in Mz with only minor changes Mn.

The peroxide is preferably dry mixed with the polylactide polymer and conglomerated to use a two screw extruder at a temperature appropriate for the peroxide. Typically, temperatures of between about 180 ° C and 210 ° C are preferred. the molar ratio of peroxide to polymer is typically about 0.01: 1 to 10: 1 (more preferably 0.05: 1 to 3: 1). These peroxide levels will generally provide sufficient polymer action and will improve rheology. In such circumstances, the average molecular weight number of the polymer increases with only about 10%, while the weight average molecular weight increases by about 20% or more. Peroxide molar ratios with polymer above about 10: 1 are believed to probably cause excess gel formation in typical systems. A more preferred molar ratio of peroxide to polymer is between about 0.1: 1 to about 0.4: 1. This usually corresponds to a weight percent in the range of about 0.05% by weight to about 0.2% by weight, based on the weight of the total composition. It should be appreciated that the above molar ratios of peroxide with polymer correspond to approximately the weight percent ranges between about 0.005 weight percent to about 0.03 weight percent and between about 1.5 weight percent to about 5 percent. in weigh.

Applicants have found that it is beneficial to improve the polylactide grade coating with optical purity. Generally, the optical purity will provide an improved crystallinity. As discussed previously, improved crystallinity (approximately 10 J / g provide the desirable properties). In particular, semicrystalline granules tend to avoid the adhesion or blocking problems normally associated with amorphous polylactide granules. It is believed that the higher vitreous transition temperature of semicrystalline polylactide granules contributes to this advantage. In addition, semicrystalline polylactide can be dried at higher temperatures than amorphous polylactide. However, optical purity should not be so great because it causes crystallization when applied as a coating. That is, unless it is desired to provide crystallization in the coating. It has generally been found that crystallization in the coating tends to contribute to shrinkage and / or opacity, and requires higher temperatures to seal with heat. The polylactide grade coating preferably has an optical purity of the S-lactic acid residues of between about 90 and about 99.5%, more preferably between about 92 and about 98%, and more preferably between about 95% and about 96.5%. Alternatively established, the optical purity of the polylactide grade coating provides R-lactic residues between 3.5 and about 5%. It should be understood that the conversion of these values is expected to be true. That is, the optically pure coating grade polylactide must be obtained with a large amount of R-lactic acid residues and with a low amount of S-lactic acid residues.

Preferred polylactide polymers for use in paper coating are preferably melt stable. Thus, it is believed that the polylactide polymer will be relatively stable to lactide reformation and depolymerization at temperatures encountered in the melting process. With respect to this, the disclosure concerning the melt stability provided in US Pat. Nos. 5,338,822 and 5,525,706 is incorporated herein by reference.

Further, it should be understood that preferred melt-stable polylactide compositions preferably include a lactide concentration of less than about 2% by weight, more preferably a lactide concentration of less than about 1% by weight, and even more preferably a concentration of lactide less than about 0.5% by weight. More preferably, to ensure the properties of melt stability, it is preferred that the lactide concentration is less than about 0.3% by weight. Furthermore, it is preferred that the degree of lactide generation during the melting process, such as through an extruder, provides the generation of less than about 2% by weight of lactide. Of course, the higher melting stability of the polylactide polymer is a result of the low levels of residual lactide, the lower the expected additional lactide will be generated during the melting process. Thus, it is expected that for melt-stable polylactide polymers, the melting process will only generate less than about 1% of the lactide, and even more preferably less than about 0.5% by weight of the lactide. Since the low level of residual lactide may be important in maintaining melt stability, it should be appreciated that additional additives may additionally depend on providing melt stability. Examples of additives are described in the two patents referred to above. It will be appreciated that several of the Examples disclose the use of tartaric acid as stabilizer for polylactide polymers. It is expected that the additional carboxylic acids will function to improve the stability of the polylactide polymer during the melting process.

It should be understood that the polylactide polymer is sensitive to moisture. Accordingly, it is desired to reduce the water content in the polylactide polymer to a level that the polymer is stable to melting. When coating grade polylactide polymer is fed to the processing equipment for coating formation, it is generally desired to run the polylactide polymer through the line dryer to reduce the moisture level to less than about 500 ppm, and more preferably less than 200. ppm. the most preferred levels of water, if the water is present, is less than about 100 ppm and more preferably less than about 50 ppm. In preferred coating operations, the polylactide polymer is not exposed to the ambient atmosphere between the step of Inline stretch and melting step of the polymer.

As discussed above, the coating conditions of the paper are very extreme, which promotes the reformation of lactide and the degradation of molecular weight. The processing temperature frequently exceeds 260 ° C. As a result, the conditions during the coating of the paper favor the degradation of the polymer. Applicants have found that it is advantageous to improve the melt stability beyond the melt stability requirements frequently encountered during film formation or molding.

C. Copolymers Polymers containing residual lactic acid include copolymers and are generally prepared from monomers including lactic acid, lactide, or combinations thereof. The polymers that are considered acid Residual lactic acid containing polymers include poly (lactide) polymers, poly (lactic acid) polymers, and copolymers such as random copolymers and / or blocks of lactide and / or lactic acid. The lactic acid compounds that can be used to form the residual lactic acid-containing polymers include L-lactic acid and D-lactic acid. The lactide compounds that can be used to form the residual lactic acid-containing polymers include L-lactic acid and D-lactic acid, and meso-lactide. A particularly preferred copolymer includes residues of residual L-lactide and residual D-lactide as comonomers.

Polypectides with modified viscosity are preferred to provide dilation in the beneficial die. These polymers are described in detail in U.S. Patent No. 5,359,026 and U.S. Patent Application Serial No. 08 / 729,732, filed by Gruber et al. on July 27, 1994, entitled "Viscosity-Modified Lactide Polymer Composition and Process for Manufacture The polylactide polymers with modified viscosity are important because they provide desirable processing characteristics such as reduced viscosity, increased melt strength.

Particularly preferred modified viscosity polylactide polymers include epoxy lactide copolymers and multifunctional oils such as flax seed oil and epoxy soybean oil. In several situations it is preferred that the polymer was prepared with multi-functional epoxy oil with 0.1 to 0.5% by weight and molten lactide monomer. The catalyst can be added, and the mixture can be polymerized between about 160 ° C and 200 ° C.

It should be understood that different types of compounds or reagents can be introduced into the polylactide polymer, the presence of these does not necessarily cause them to repeat units. Clearly, the presence of a compound or This residue with a concentration that corresponds to the presence of a few compounds or residues in a polymer chain does not repeat.

Other preferred copolymers include copolymers of PLA with other biodegradable polymers, especially aliphatic polyesters. The preferred method for forming the copolymers would be through interesterification or coupling in a post-polymerization process, such as reactive extrusion. Extrusion in the presence of peroxides can be a method to provide the coupling while creating non-linear polymer molecules. Alternatively, copolymers of lactide and other cyclic esters, cyclic ethers and cyclic amide esters are possible. The comonomers in this case would include a lactide with glycolide, paradioxanone, morpholinindinones, dioxepan-2-one, dioxanones (such as p-dioxanone), lactones' (such as epsilon-capproláctone or 4-valeroláctone), dioxan (dione) s (such as glycolide or tetramethyl-1,4-dioxan-2,5-dione) or amide esters (such as morpholino- 2,5-dione). With respect to the copolymers, reference may be made to U.S. Patent No. 5,359,026, the disclosure of which is incorporated herein in its entirety. Also, the copolymers of lactic acid and other hydroxy acids or low molecular weight polyesters terminated with hydroxy and / or acids. Aliphatic polyesters or amide polyesters are preferred.

D. Other Compounds The composition of the polylactide polymer includes the additional compounds or additives that include, plasticizers, rheology modifiers, crystallinity modifiers, antioxidants, adhesion enhancing additives, stabilizers, pigments, nucleating agents, and the like.

Plasticizer For most polymers containing residual lactic acid, it is believed that the vitreous transition temperature can be lowered to desirable levels by adding a plasticizer compound to provide a concentration of about 0.5 to 20 weight percent plasticizer, based on the weight of the composition of the polymer. Generally, a sufficient amount of plasticizer must be incorporated to provide a desired reduction in Tg. It is believed that the level of plasticizer should be greater than at least 1 percent by weight, and more preferably above at least 2 percent by weight, to provide sufficient flexibility and softness. Accordingly, if the plasticizer is used, it must be included to provide a concentration level of about 1 to 10 weight percent.

The selection of the plasticizer may involve the concentration of several criteria. In particular, due to the large area of the polymer exposed during the formation of the film, it is desired to provide a plasticizer that does not volatilize to a significant degree. In addition to the reduction of gases, this would originate the reduction of the laminate. It is generally desirable to provide as much biodegradability as possible, it is preferred to use a plasticizer that is biodegradable, non-toxic, compatible with the resin and relatively non-volatile.

The plasticizer of the general classes of esters, alkyl or aliphatic esters and multifunctional functional esters and / or ethers is preferred. These include alkyl phosphate esters, dialkylether diesters, tricarboxylic esters, epoxide oils and esters, polyesters, polyglycol diesters, alkyl alkyl ether diesters, aliphatic diesters, alkyl ether monoesters, citrate esters, dicarboxylic esters, vegetable oils and their derivatives, and glycerin esters. Preferred plasticizers are tricarboxylic esters, citrate esters, glycerin esters and dicarboxylic esters. More preferably, citrate esters are preferred since it is believed that these esters are biodegradable. These plasticizers can obtained with the names of Citroflex A-4®, Citroflex A-2®, Citroflex C-2®, Citroflex C-4® (from Morflex).

The volatility is determined by the vapor pressure of the plasticizer. An appropriate plasticizer must be sufficiently non-volatile such that the plasticizer remains sufficiently in the composition throughout the process necessary to produce the multilayer structure and to provide desired properties when the structure is used. Excessive volatility can cause contamination of the process equipment, and may cause undesirable migration of the plasticizer. The preferred plasticizer should have a vapor pressure less than about 10 mm Hg at 170 ° C, and more preferably the plasticizer should have a vapor pressure less than 10 mm Hg at 200 ° C. a more preferred plasticizer has a vapor pressure of less than 1 mm Hg at 200 ° C. The internal plasticizer that binds with the polymer containing the residual lactic acid may also be useful in the present invention.

The exemplified plasticizer that can be attached to the polymer include epoxides. Plasticizers that are normally solid at room temperature can be used additionally.

Agents for the Formation of Nuclei In the present invention, a polymer composition is considered to be semi-crystalline if it exhibits an endothermic melting network greater than 10 J / g of the polymer when analyzed by differential calorimetric scanning (DSC). To determine if the layer of the polymer composition is semi-crystalline, it can be tested in a differential scanning calorimeter, such as Mettier. The details of the development of the crystallinity test are known to persons with experience in the art and are identified in the Application of the North American Patent Series No. 08 / 110,394, registered on August 23, 1993, the entire exhibition is incorporated herein as reference.

Yes a semicrystalline coating is desired (greater than 10 J / g), agents for the formation of nuclei can be incorporated. Core forming agents may include selected plasticizers, finely divided minerals, organic compounds, salts of organic acids, and imides and finely divided crystalline polymers with a point of 'melting above the processing temperature of the poly (lactide). Examples of nucleating agents include talc, sodium salt of saccharin, calcium silicate, sodium benzoate, calcium titanate, boron nitride, copper phthalocyanine, isotactic polypropylene, low molecular weight poly (lactide) and polybutylene terephthalate. A semicrystalline coating may be desirable in situations where the development of high temperatures (improved heat resistance) and better barrier properties are desired. Exemplary applications where a semi-crystalline coating may be desired include hot beverage cups, hamburger wrappers, and food carrying containers.

It should be understood that it is generally desired for the coating to be amorphous. An amorphous polylactide coating generally provides the desired clarity. Semi-crystalline polylactide coatings tend to become opaque or white. Amorphous polylactide coatings are generally preferred when it is desired to improve a coating that does not tend to shrink. In contrast, if the coating becomes an amorphous coating which crystallizes while solidifying, the coating will tend to cause the paper to roll up. Of course, it can be advantageous to provide a coating that causes the paper to roll up. In general, it is desired to provide a coating that does not cause the paper to wrap. This coating can be obtained if the polylactide polymer composition is applied as an amorphous coating, and solidifies as an amorphous coating.

Amorphous polylactide coatings are generally preferred in situations where heat sealing is an important property. As discussed above, ownership of the Heat sealing allows the polylactide coating to melt under pressure and provides a heat seal. This is an important feature in the formation of cups. Generally, an amorphous polylactide coating will seal with heating at a temperature above the vitreous transition temperature. Accordingly, by heating the polylactide coating above 60 ° C, it is possible to improve a heat seal. Accordingly, the use of adhesives can be reduced or eliminated.

An amorphous polylactide coating is also preferred when it is desired to provide a coating that degrades faster than, for example, semicrystalline polylactide. Generally, the amorphous structure will be composited faster under composting conditions than semicrystalline polylactide.

The amorphous coating tends to be more flexible than semicrystalline polylactide coatings. This is an important consideration, when for example, you want roll the coated paper backing to form a rim in a cup. It is generally not desired for the coating to break under one application. In addition, an amorphous polylactide coating generally provides better adhesion to paper compared to the semicrystalline polylactide coating.

Filling Agents Low levels of fillers may be useful to prevent blockage or adhesion of the coated paper product during storage and transportation. The inorganic filling agents include clays and minerals, modified on their surface or not. Examples include talc, diatomaceous earths, silica, mica, kaolin, titanium dioxide, and wallastonite. Inorganic fillers are environmentally stable and non-toxic.

Organic fillers include a variety of forest and agricultural products, with or without modification. Examples include cellulose, wheat, starch, starch modified, chitin, chitosan, keratin, cellulosic materials derived from agricultural products, gluten, nut shell flour, wood flour, corn cob meal, and guar gum. Preferred fillers are derived from renewable sources and are biodegradable. The fillers can be used alone or as a mixture of two or more fillers. Preferred filler levels, if all are used, will be less than 10% by weight and more preferably less than about 5% by weight.

Surface Treatments Surface treatments can be used to reduce blockage. These treatments include powder coating the surface with materials that reduce contact with the surface between the polylactide base coat and the adjacent surface. Examples of materials that can be used in surface treatments include talc, silica, corn starch, flour of corn, latex spheres, or other particles. Surface treatments include chemical and physical treatment. These treatments include crown and flame treatments which increase the surface energy of the coating based on poly (lactide). The processes of corona treatment and flame are conventional and are described in detail in the TAPPI "Manual Film Extrusion", 1992, chapter 8, p. 129-150, the exhibition of this is incorporated here as a reference in its entirety. In most applications where polylactide based coatings are corona or flame treated, it is expected that a tempered corona treatment will give the surface energy of the polylactide up to about 45-50 dynes.

Lubricants For certain applications, it is desirable for the coating to have good sliding properties. Solid lubricants, such as powders, are sometimes incorporated. fluoropolymer or graphite to increase the sliding properties. Commonly fatty acid esters or hydrocarbon waxes are used as lubricants for the molten state, they are exudated gradually, if they are used with high concentrations, they allow permanent effects of lubrication. Certain additives migrate or strengthen on the surface, even during cooling, where an invisible coating is uniformly thin. Thus, these slip agents can be important in the production of coating which are used in automatic packing machines. It has been found that preferred lubricants reduce the amperage for the operation of the screw of an extruder by about 10 to about 15% when about 1000 ppm by weight is added (compared to the amperage without lubricant).

The internal lubricants that can be used in the present invention include esters of fatty acids, amides, salts and soaps of metals, and paraffin or hydrocarbon waxes.

Examples of useful lubricants include zinc stearate, calcium estereate, aluminum stearate, acetyl stearic, white beeswax, candelilla wax, LDPE with high MFI, Eastman Epolene N21, Eastman Epolene E20, and Loxiol HOB7119, Preferred internal lubricants include estereate of aluminum and stearic acetate.

Natural and synthetic waxes, and these waxes are typically used in paper coating applications that can be used to provide lubricity, anti-blocking properties, and improve gloss.

Antistatic agent Antistatic agents can be employed in the present invention. Antistatic agents are reactants that can be subdivided into cationic, anionic and non-ionic agents.

With respect to cationic compounds, the active molecular part generally consists of a bulky cation that frequently contains a long alkyl residue (for example, a quaternary ammonium, phosphonium or sulfonium salts) by means of which the quaternary group may also find a ring system (for example, imidazoline). In most cases, the anion is chloride, methosulphate or nitrate that originate from the quaternization process.

In the anionic compounds, the part of the active molecule in this case of compounds is the anion, most often a sulfonate or alkyl phosphate, a dithiocarbamate or carboxylate. The alkali metals often serve as cations.

Non-ionic antistatic agents are molecules with discharged active surface of a significantly lower polarity than the ionic compounds mentioned above and include polyethylene glycol esters or ethers, fatty acid esters or ethanolamides, mono- or diglycerides or ethoxylated fatty amines.

Reagents For certain applications, it is desirable for the coating to be modified to alter the properties of water transport. Reagents can be incorporated into the network of the present invention to increase the water transport properties.

Reagents that are useful can be subdivided into cationic, anionic, or non-ionic agents.

Pigments The pigments, dry, or colored agents can be added if necessary. Examples include titanium dioxide, clays, calcium carbonate, talc, mica, silica, silicates, oxides and hydroxides of iron, carbon black and magnesium oxide.

Additives that Improve Adhesion In certain applications, it is desirable to provide additives that improve the adhesion of the coating to the substrate. A general class of these additives can be referred to as adhesion additives. It is believed that these additives tend to decrease the viscosity of the molten polylactide polymer which, in turn, promotes the adhesion of the molten polylactide polymer to a substrate, especially paper. Additives that may be useful with respect to this include plasticizers, lactic acid oligomers, low molecular weight polylactide and tackifying resins. Preferred additives are relatively polar and have a solubility parameter close to that of polylactide. Preferably, the solubility parameter will be within about 5 cal ° "5 / cm 3. These additives will preferably be added in an amount of between about 1 and about 10% by weight and more preferably between about 3 and about 8% by weight.

Catalysts In the manufacture of the polylactide compositions of the present invention, the reaction is catalyzed to polymerize the lactide. Several catalysts have been cited in the literature for the use in polymerization of opening lactone rings. These include but are not limited to: SnCl2, SnCl, SnBr4, aluminum alkoxides, tin alkoxides, zinc alkoxides, are, PbO, Sn (2-ethyl hexanoates), Sb (2-ethyl hexanoates), (some sometimes called octoatos) estereatos of Ca, estereatos of Mg, estereatos of Zn, and tetrafeniltin. Applicants have also tested several catalysts for the polymerization of lactides at 180 ° C, which include: tin (II) bis (2-ethylhexanoate) (commercially available from Atochem, such as Fascat 2003 and Air Products as DABCO T-9), dibutyltin diacetate (Fascat 4200®, Atochem), butyltin tris (2-ethylhexanoate) (Fascat 9102®, Atochem), monobutyl hydrated oxide (Fascat 9100®, Atochem), antimony triacetate (S-21, Atochem), and tris Antimony (ethylene glycoxide) (S-24, Atochem). Of these catalysts, tin (II) bis (2-ethylhexanoate), butyltin tris (2-ethylhexanoate) and dibutyltin diacetate appear to be the most effective.

Oils for the finished For some applications, it may be useful to apply surface treatments to provide lubricity, hydrophilic change, alter static characteristics and affect cohesion.

An example of these surface treatments are the oils for the finish. Oils for finishing can affect the previous fiber properties, but also affect downstream fiber formation processes.

These processes include the manufacture of spinning and carding. Examples of some of the finishing oils that could be used for PLA include esterases or other commercially available suitable oils.

Peroxides Preferred peroxides are dialkyl peroxides. Examples of dialkyl peroxides include dicumyl peroxides; a, a'-di (t-butylperoxy) diisopropylbenzene; 2, 5-dimethyl 1-2, 5-di (t-butylperoxy) exano; t-butylcumyl peroxide; di-t-butyl peroxide; and 2,5-dimethyl-2,5-di (t-butylperoxy) 3 -hexine. Particularly preferred is 2,5-dimethyl-2,5-di (t-butylperoxy) hexane available from Varox DBPH-50 by R. T. Vanderbilt or Luperco 101-XL from Elf Atochem.

Other Polymers As discussed above, different types of polymers can be mixed with polylactide and used in the present invention. Examples of types of polymers that can be mixed with polylactide include polyolefins, polyamides, aromatic / aliphatic polyesters, including polybutylene terephthalate and polyethylene terephthalate, and combinations thereof. Additional types of polymers that can be used include destructurized starch compositions, polyhydric alcohols and derivatives, hydroxypropyl cellulose derivatives, cellulose esters, biodegradable aliphatic polyesters, ethers, urethanes, and biodegradable aliphatic-aromatic polyesters. Examples of destructurized starch compositions include starch in combination with ethylene vinyl alcohol (EVOH) available as Mater-Bi from Novamont. Examples of polyhydric alcohols and derivatives include polyvinyl alcohol modified with appropriate plasticizers, such as glycerol, ethylene glycol, polyvinyl alcohol in combination with poly (alkenoxy) acrylate which is available as Vinex from Air Products and Chemicals. An example of hydroxypropyl cellulose derivatives include nonionic cellulose ether of hydroxypropyl cellulose, such as those available as KLUCEL from Hercules. Examples of cellulose esters include cellulose acetates (Tenites available from Eastman and include propionates and butyrates, cellulose acetate propionates, cellulose acetate butyrates, etc.) Examples of polyesters Biodegradable aliphatics include polyhydroxybutyrate (PHP), polyhydrobutyrate-co-valerate (PHBV) available as Biopol, polycaprolactane available as Tone from Union Carbide, polybutylene succinate available as Bionelle 1000 series by Showa, polybutylene succinate-co-adipate available as Bionelle 3000 by Showa , polyglycolic acid (PGA), various grades of polylactide (PLA), polybutylene oxalate, polyethylene adipate, polyparadioxanone, polymorphinevinion, and polydioxipan-2-one. Examples of ethers include polypropylene oxide and copolymers of polypropylene oxide and polyethylene oxide and polyethylene oxide copolymers. Examples of polycarbonates include polyethylene carbonate, polybutylene carbonate and polytrimethylene carbonate and their derivatives. Examples of urethanes include urethanes made with polyester or ethers or mixtures thereof, or made with polyesters and urethanes to provide aliphatic polyester urethanes. Biodegradable aliphatic-aromatic polyesters include polybutylene succinate-co-terephthalate available from Eastman, and Biomax from Dupont.

Additional compounds that can be mixed with PLA or used as other multicomponent film compounds include thermoplastic resins such as hydrocarbons, polyesters, polyvinyl alcohols, poly (acrylonitrile) polymers, and highly substituted cellulose esters. Examples of hydrocarbons include polyethylene polypropylene. Examples of polyesters include aromatic polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Polymers that can be used in the present invention include PLA and PLA-based polymers, other biodegradable or water-soluble polymers, such as PVA, other lactic acid-containing polymers (e.g., lactic acid-based polyurethanes, polycaprolactone (PCL) ), polypropiollactone, polymeric cellulose acetates containing glycolides (PGAs), degradable polyesters (aliphatics), polyhydroxypropionate (or butylate, capreolate, heptanoate, valerate or octanoate), polyesteramides, polymers of aliphatic diols, aliphatic and aromatic dicarboxylic acids, and, where applicable, copolymers and mixtures thereof. An exemplary preferred polymer is a polybutylene succinate homopolymer sold under the tradename of Bionelle 1000 ™ and is available from Showa High Polymer Co. Ltd.

B) Generally Paper According to the present invention, the polylactide polymer composition can be coated on any substrate where it will adhere. Examples of substrates include natural and synthetic paper, polymer films and aluminum foils. Preferably, the polylactide polymer composition is coated on paper such as bleached and unbleached Kraft paper, clay coated paper, bleached and unbleached packaging paper, bleached box paperboard and the like.

Paper of several weights can be used. For example, in the manufacture of a rate, it is generally desired to use a paper having a weight between about 210-250 g / m2.

Example 1 Paper with High Gloss, Water Resistant, with Biodegradable Coating A 20% solution of poly (lactide) with a molecular weight of 40,000 in a chloroform solvent was deposited on 50 lb. Kraft paper (Georgia Pacific) using a 15 mil drawbar. After the coating was allowed to dry at room temperature for 24 hours, the coated paper was placed in a vacuum oven at 40 ° C and under high vacuum for 24 hours to remove the residual solvent. The coating thickness after drying was 2 mils. The resulting coating had excellent clarity and high gloss; a value of 60 ° brightness of 83 was found according to ASTM D 523-85. Exposing the coating to water for 8 hours did not affect its appearance. The flexibility of the coating was verified at fold the liner over a 1/8"mandrel.

Example 2 Heat Sealing Capacity of a Coating with Biodegradable Paper A 20 percent poly (lactide) solution in chloroform was deposited on 50 lb. Kraft paper (Georgia Pacific) using a 15 mil and one 25 mil draw bar. The coated paper was allowed to dry at room temperature for 24 hours. The residual solvent was removed in a vacuum oven at 30 ° C under high vacuum. The thickness of the dry coating was 2 thousand and 4 thousand respectively.

Its heat scalability on uncoated paper was tested on coated paper using a 1"wide test specimen. A Sencorp Heat Sealer Model 12-As / l was used to apply a pre-set pressure for a given time and temperature. two jaws of 1 x 12 ''. The 1"wide coated paper was framed to an uncoated paper of the same dimensions. The pressure was varied from 60 to 80 psi, the temperature was from 200 ° to 280 ° F, and the time from 0.5 to 1.5 seconds. The samples were allowed to cool to room temperature. The quality of the resulting bond was evaluated hereafter using a T-peel test by hand and the degree of tearing of the substrate fiber was judged visually.

The samples were judged as "excellent" heat seal (2) if they had 100% tear of the fiber of the uncoated strip on the coating. A "good" heat seal (1) was partial tearing of the uncoated strip. Sealing with "poor" heat (0) does not indicate the tearing of the fiber. The tests were performed using a coating of 2 thousand and 4 thousand. An * indicates an average of multiple tests. The following are the results: TABLE 1 O = POOR 1 = GOOD 2 = EXCELLENT AVERAGE OF MULTIPLE TESTS Time (Sec.) 1.5 1.0 0 2 * 2 * 0.5 0 0 0 0 0 0 * 0 * 1.5 * 220 210 220 230 240 250 260 270 280 TEMPERATURE ° (F) Due to the thermoplastic nature of the coating, the bonded substrates can be peeled off by the application of heat and stress to the bond line where the coating is softer. This offers an additional option for recycling coated paper.

Example 3 Ability to Extract the Pulp of the Biodegradable Coating at pH 7 A 20 percent poly (lactide) solution in chloroform was deposited on 70 lb. Kraft paper (Georgia Pacific) and dried at room temperature overnight. The residual solvent was removed in a vacuum oven at 30 ° C under high vacuum. The thickness of the dry coating was 5 mil.

Several pieces of one square inch of coated paper were placed in one liter of water 140 ° F pH 7 in a Waring blender. The solid contents were 2 percent w / v. The coated paper was mixed in a fixed size cutting machine for 8 minutes. The lining of the pulp was removed by filtering through a No. 5 screen. Although a small amount of fiber remained adhered to the coating, the ability to compost the mixture would be excellent. Also the recovery of the lactic acid from the hydrolysis of the coating would not be an obstacle due to the presence of very low levels of wood fiber.

Example 4 The ability to extract the pulp from the biodegradable coating under alkaline conditions Pieces of one square inch of the coated paper prepared in Example 3 were placed in one liter of water pH 10, 140 ° F in a Waring blender. The content of the solids was 2 percent w / v. After stirring for 8 minutes in a fixed cutting machine, the fibers were recovered by filtering through a No. 5 screen. Although a small amount of fiber remained adhered to the coating, the ability to compost the mixture would be excellent. Also the recovery of the lactic acid from the hydrolysis of the coating would not be an obstacle due to the presence of very low levels of wood fiber.

Example 5 Examples of Coating Two samples of melt-stable poly (lactide) were used in a continuous paper coating test. The poly (lactide) was dried and the vapors were removed, with an initial lactide concentration of 0.5 weight percent. Poly (lactide) was produced from lactide using catalyst with a 5,000: 1 molar ratio ratio of monomer with catalyst. The catalyst was bis (2-ethylhexanoate) tin (II). The stabilizer (Weston PNPG) was added at the beginning of the polymerization with a proportion of 0.2 weight percent. The first sample of poly (lactide) had an initial weight average molecular weight of 75,000 and the second had an initial weight average molecular weight of 105,000.

Poly (lactide) was melted in a reservoir and then pumped through the die to produce an 8"wide coating, using a May Coating Technologies CLS-300 coater and model 50B melt tank. The die was placed in place by pneumatic pressure and floated against the substrate between a fusion pad. The substrate was paper Natural kraft, 50 lb. basis weight, 12"wide.

The molecular weight test 75,000: the polymer was melted and pumped at temperatures of 190 ° -200 ° C. The pumping speed was maintained at 2.6 lb / min and the line speed was set at 375 feet per minute and 75 feet per minute to give a thickness of. coating of approximately 1 thousand and 5 thousand, respectively for the coating of 5 thousand, the temperature in the rolling was of 80 ° C so a coated film was released (MYLAR ®) was wound to remove the block. In subsequent runs a cooling roller was incorporated and no film release was used.

The 105,000 molecular weight test: the polymer was melted and pumped at temperatures of 215 ° -227 ° C. In a reservoir at a temperature of 227 ° C, there were no notable vapors. The pumping speed was set at 2.6 lb / min and the line speed was set at 375 feet per minute to give a coating thickness of approximately 1 one thousand. Additional tests were made at line speeds of 150 feet per minute at 500 feet per minute, giving a coating thickness of 2.5 thousand, to 0.75 thousand respectively.

The coatings had high gloss and had excellent adhesion to the paper. The coatings exhibited good water repellency, high tear resistance, and rigidity was increased.

The blocking of coated paper PLA (2.5 mils) at three temperatures at 25 °, 53 ° and 63 ° C under a load of 17.5 ounces applied in an area of 262.5 square centimeters was tested, using a film-to-film substrate placement, paper to film, film to film (powdered with talcum powder). After 24 hours paper to film and film to film (powdered with talcum) showed no blockage at 25 °, 53 ° and 63 ° C while the placement of the film on the substrate film showed no blocking at 25 ° C and block at 53 ° C.

Example 6 Effect of Modification of Properties with Peroxide In this example, four resins were treated with two levels of peroxide to determine the effect of peroxide crosslinking on polymer properties such as Mn, Mz, Mz + 1, melt flow index (MFI), dilation in the die, neck of entrance during the extrusion of the film deposition. The four samples of resins, labeled AD, were all prepared in semi-working scale plants using batches of 4,000-6,000 pounds and included 0.35% by weight of epoxidized soybean oil (available as PARAPLEX G-62, from CP Hall Company ) as a copolymerization agent, tin (II) bis (2-ethyl hexanoate) as a catalyst with a molar ratio of 1 part of catalyst with 80,000 parts of lactide (catalyst available from DABCO T-9, from Air Products Company) , and a stabilizing process (typically TNPP from GE Specialty Chemicals). The temperature of polymerization was about 180-200 ° C for a time of about 9-13 hours. The vapors were removed from the samples using a twin-screw extruder and a clean film evaporator, leaving a residual lactide content of less than 1% by weight. The polymer was then granulated and dried.

The samples were prepared by dry blending a peroxide (Varox DBPH-50 from RT Vanderbilt Co. Which is 45% by weight of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane in 1: 1 calcium carbonate mixture: inert silicone filler) in 0.05% by weight or 0.10% by weight granules of a dry polymer and reacts with these when extruded at 10 lb / hr in a Leistritz double screw extruder. mm. The extruder was run at a speed of 100 r.p.m. and a temperature of 180 ° C with a residence time of about three minutes. The extruder has 11 zones, numbered. starting in the first section, with temperatures of 160 ° C in zone 1, 175 ° C in zone 2, 180 ° C in zone 3-9, and 185 ° C in zones 10-11. The samples were also prepared by using an extrusion temperature of 210 ° C and similar results were obtained, although there was more dispersion in the data and evidence of thermal degradation (degradation in the number of the average molecular weight). The extrusion was carried out under vacuum to eliminate the products of the volatile decomposition. The resin was then formed into granules, dried, and collected at 110 ° C for 12 hours to crystallize the granules. Crystalline granules have been found to cause fewer problems with adhesion to the screw when processing poly (lactide) into single screw extruders. The control samples without the addition of peroxide were processed in the same way as the samples treated with peroxide so that they had the same thermal history.

The samples were then tested for several of their properties. Gel Permeation Chromatography (GPC) was used to determine different molecular weight averages, including Mn, Mw, Mz, Mz + 1. This procedure has been previously described. The determination of Die Dilation and Fusion Fluency Index in a Tinius Olsen Fusion Indicator, model MP993, using a die diameter of 0.0825 inches at 210 ° C under a load of 2.16 kg. This procedure has been previously described.

The development of the samples in a small film deposition line was used to determine the propensity of the entrance neck, as follows. In a one-inch Killion single screw extruder operated at a temperature of 170 ° C with a screw speed of 40 r.p.m. it was used with a six inch film deposition die, also at 170 - to deposit by extrusion a film on an eight inch diameter receiving roll that runs at twelve r.p.m. The entrance neck is reported as the width of the die (six inches) minus the width of the deposited film, in inches.

The results are shown in Table 2 and the Figs. 8 and 9. The data shows that the entrance neck is correlated strongly with Mz / Mn (Fig. 9). The data also show the dramatic increase in Mz / Mn when it is entangled with peroxide, causing an increase in the compounds of higher molecular weight. The entrance neck was dramatically reduced.

Table 2 Effect of the Modification with Peroxide in the Properties of Several Degrees of PLA Example 7 Effect of Peroxide Level in the Distribution Mol. Weight A resin, similar to the previous Example, was treated with three different levels of peroxide (Varox DBPH-50, RT Vanderbilt Co., 45% of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane in a inert filler). In addition to the peroxide, 1000 ppm of aluminum stearate and 500 ppm of tartaric acid were added. The materials were mixed dry (except for the control) and reacted in an extruder at 180 ° C, as the previous example. The results are shown in Table 3. The data show a modest change in the number of the average molecular weight but a dramatic increase in molecular weights, average weight, Z-average, Z-average + 1. The increase in the higher averages is directly the response to the amount of the added peroxide. The dilation in the die increased with the increase in Mz / Mn, indicating improved properties for extrusion coating operations. He Melt flow index (MFI) decreases slightly by increasing the level of peroxide.

GPC results were used to determine in more detail if molecular weight changes occurred. The data show that the lower molecular weight fraction (< 10,000 AMU) remained at a low level (2.5% by weight the least) for all samples. The very high molecular weight fraction (> 500,000 AMU) was constantly increased by increasing the peroxide level in the treatment, being from 4.6% by weight in the base material to 12.3% by weight in the higher level of the treatment.

Table 3 Effect of Various Amounts of Peroxide on Polymer Properties and Weight Distribution in Weight Example 8 Paper Coating Test with Various Resins Two resins (A and D in Table 4) were prepared in a manner similar to Example 6. These resins were modified by mixing in a twin screw extruder 0.05% by weight or 0.10% by weight (peroxide base) of Varox DBPH-50 from RT Vanderbilt Co. (45% 2,5-dimethyl-2,5-di (t-butylperoxy) hexane in an inert carrier) in a manner similar to Example 6. These resins were labeled B, C, E and F in Table 4. The properties of the resins and the effects of the peroxide treatment are shown in the table, with results generally similar to those detailed in Examples 6 and 7. In particular, the peroxide treatment effectively increased the dilation in the die , and Mz / Mn with minimum changes in Mn.

The dried, crystallized resins were processed in a paper coating line to produce a coating of 0.6-1.2 mils, depending on the conditions. Paper It was 50 lb. Kraft paper. The width of the die was 28 inches and a resin production of 1701b / hr was supplied using two extruders (one single screw 2-inch at 80 rpm and one single screw 2.5 inches at 60 rpm) feeding a die simple, giving a raw material processing of 6 pounds per hour per inch of the die (pph / in). The air space was adjusted to 3 inches, this was as low as it could be practical. Generally a small air gap allows good adhesion at low melting temperatures, reducing thermal stress on the polymer.

Each of the resins was processed at the specific temperature in Table 4 and at a variety of line speeds (reported in feet per minute). The energy and pressure head of the extruder were reported and a slight increase in the required energy and head pressure is shown for the high peroxide levels in the treatment, although the increase in the melting temperature helps to moderate this effect. The energy and pressure head can be critical factors, when polylactide resins are extruded, and only modest increments, as shown here, could be tolerated.

The coating tests, indicated by the neck entrance% (calculated as 100 * (width of the die-width of the coating) / width of the die) and TAPPI adhesion (stretch test of the tape, with 5 indicating complete adhesion and 1 indicating no adhesion of the coating to the paper), and comments indicating the presence of excessive edge waving (1/4 inch or more) are also shown in the Table.

Observing first the base resins (A and D) show the maximum line velocity of approximately 200 fpm before the rippling of the edge is noticed, with approximately 17% of entry neck. In comparison, the peroxide-treated resins were processed at speeds of at least 300 fpm and in some cases 450 fpm without edge waving, and with only 11-16% inlet neck. These are improvements significant in terms of raw material processing of a paper coating line and in terms of reducing the polymer and residual paper associated with the inlet neck. The adhesion, in all cases, was reduced while the line speed was increased. The peroxide-treated coated resins show comparable adhesion to the base case resins at comparable speeds, except for the F resin which is processed at a higher temperature. The higher operating temperature is seen to increase adhesion. The current maximum line speed will be greater for large-scale equipment and will improve the adhesion obtained with large quantities of raw material processed to produce polymer.

Table 4 Paper Coating Test with Various Grades of PLA Resins Modified with Peroxide Re- MFI Dilata Mn Mw Mn / Mz Mz / Mz + 1 Mz + l / M% of Actuation of Mw Mn n C mbio Die of Mn 28 1.6 68000 139600 2.05 239000 3.51 384000 5.35 B 0.05 16 1.31 72300 177300 2.45 378700 5.21 667000 9.23 6.32 C 0.1 14 1.41 77500 199000 2.57 473000 6.10 900000 11.61 13.97 ~ D 0 12 1.12 83700 175500 2.10 305000 3.64 466500 5.57 E 0.05 8.4 1.36 88800 226600 2.55 520000 5.86 984600 10.86 6.09 F 0.1 7.4 1.5 85400 246700 2.89 623000 7.30 115100 13.48 2.03 0 Res% of% of% of Amps Presi Temp Velo% Cue Eat Adhe ina Acti Change Change Changing the value of the contents of the procession Mw Mz Mz + 1 Ex of the input fu TAPPI Tru extru sion line of Sor sor ( F) (fpm) (psi) A 0 34 1980 504 150 16 4 200 17 3 250 19.6 o .B 2 300 22.3 0 .B 1 B 0.05 27.01 57.62 83.24 37 2130 507 150 13 4 200 14 3 250 15 2 300 16 1 C 0.1 42.55 97.91 147.25 38 2190 508 150 11 4 200 12 3 250 14 2 300 14 1 350 14 1 400 14 1 450 15 1 D 0 45 2750 508 150 15 4 200 16.8 3 250 17.4 O.B. sl 3 300 18.6 O. B. 2 E 0.05 29.12 70.49 106.77 47 2900 512 150 14 4 200 14 3 250 15 2 300 15 1 F 0.1 40.57 104.28 146.73 47 2000 533 150 14 5 200 15 4 250 15 3 300 16 1 350 16 O. B. 1 O.B. Rim Wavy Since the invention has been described in conjunction with several specific embodiments, it is understood that various alternatives, modifications and variations will be apparent to a person skilled in the art in view of the foregoing description. Accordingly, it is intended that this invention encompass all of these alternatives, modifications and variations that fall within the scope and perspective of the claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (34)

1. A polylactide polymer composition, characterized in that it comprises polylactide polymer having optical purity of residual S-lactic acid between about 90% and 99.5%, the polylactide polymer composition has a ratio of Mz to Mn greater than about 6 and has a dilation in the larger die of about 1.25 with a melt flow index greater than about 2 as measured by ASTM D1238-95 at 210 ° C and 2.16 kg.

2. A coated paper product comprising a paper layer and a polymer layer, characterized in that the polymer layer prepared by extrusion coats the polylactide polymer composition according to claim 1 on the paper layer.

3. A coated paper product according to claim 2, characterized in that the composition of the polylactide polymer comprises peroxide-modified polylactide polymer.

4. A coated paper product according to claim 3, characterized in that the peroxide modified polymer has been prepared by combining the polylactide polymer with an alkyl peroxide.

5. A coated paper product according to claim 3, characterized in that the peroxide-modified polylactide polymer is prepared by combining the polylactide polymer and the peroxide based on the total weight of the composition which is between about 0.005 and about 0.03 percent.

6. A coated paper product according to claim 5, characterized in that the polylactide comprises residual epoxidized soybean oils.

7. A coated paper product according to claim 2, characterized in that the polylactide polymer composition has a ratio of Mz to Mn greater than about 7.

8. A coated paper product according to claim 2, characterized in that the polylactide polymer composition has a die expansion greater than about 1.4 with a melt flow rate greater than about 2 as measured by ASTM D1238-95 at 210 °. C and 2.16 kg.

9. A coated paper product according to claim 2, characterized in that the polylactide polymer composition comprises an adhesion resin.

10. A coated paper product according to claim 2, characterized in that the polylactide polymer composition has not been modified with peroxide.

11. A coated paper product according to claim 2, characterized in that the polymer layer has a surface that exhibits a surface energy of between about 38 dynes / cm and 44 dynes / cm.

12. A coated paper product according to claim 2, characterized in that the polymer layer has a surface that exhibits a surface energy greater than 44 dynes / cm.

13. A coated paper product according to claim 2, characterized in that the polylactide polymer has an optical purity of residual S-lactic acid between about 92% and about 98%.

14. A coated paper product according to claim 2, characterized in that the polylactide polymer composition has an average molecular weight in weight of between approximately 100,000 and approximately 275,000.

15. A coated paper product according to claim 2, characterized in that the polylactide polymer composition comprises at least about 70% by weight of the polylactide polymer.

16. A coated paper product according to claim 2, characterized in that the polylactide polymer composition has a melt flow index of between about 8 and about 20 as measured by ASTM D1238-95 at 210 ° C and 2.16kg.

17. A coated paper product according to claim 2, characterized in that the polylactide polymer composition comprises the polylactide polymer having an optical purity of residual S-lactic acid between about 95% and about 96.5%.

18. A coated paper product according to claim 2, characterized in that the polylactide polymer composition has a residual lactide concentration of less than about 0.5% by weight.

19. A coated paper product according to claim 2, characterized in that the polylactide polymer composition comprises a stabilizing agent.

20. A coated paper product according to claim 2, characterized in that the polylactide polymer composition comprises a lubricant selected from the group of esters of fatty acids, amides, metal salts and soaps, paraffins, hydrocarbon waxes and mixtures thereof.

21. A coated paper product according to claim 2, characterized in that the paper layer has a first surface and a second surface, the polymer layer is a first polymer layer adhered to the first surface of the layer of paper, and further comprises a second polymer layer adhered to the second surface of the paper layer.

22. A coated paper product according to claim 2, characterized in that the paper layer has a first surface and a second surface, the polymer layer is a first polymer layer adhered to the first surface of the paper layer, and in addition it comprises a second polymer layer adhered to the first polymer layer.

23. A coated paper product according to claim 2, characterized in that the paper layer includes a first surface and a second surface, the polymer layer comprises a first polymer layer, and a second polymer layer, the second polymer layer it adheres to the first surface of the paper layer, and the first polymer layer adheres to the second polymer layer.

24. A coated paper product according to any of claims 21, 22, 23, characterized in that the second polymer layer comprises a polylactide polymer.

25. A coated paper product according to claim 24, characterized in that the second polymer layer has a weight average molecular weight different from the weight average molecular weight of the first polymer layer.

26. A coated paper product according to claim 23, characterized in that the second polymer layer is selected to provide adhesion between the paper layer and the first polymer layer.

27. A coated paper product according to claim 2, characterized in that the coated paper product provides a property of grease resistance of no penetration after 65 hours at 100 ° C in accordance with the ASTM F-119 method test.

28. A coated paper product according to any of claims 21, 22, 23, characterized in that the second polymer layer comprises a polymer selected from the group consisting of unstructured starch compositions, polyhydric alcohols and derivatives, hydroxypropyl cellulose derivatives, esters of cellulose, biodegradable aliphatic polyesters, esters, urethanes and biodegradable aliphatic-aromatic polyesters.

29. A method for preparing a coated paper product, according to claim 2, characterized in that the method comprises the steps of: (a) providing the polylactide polymer composition according to claim 1 in the form of granules having a higher crystallinity of approximately 10 J / g; (b) melting the polylactide polymer composition to provide a polylactide polymer composition; and (c) extrusion coating the molten polylactic polymer composition on the paper layer to provide the coated paper product.

30. A method for coating paper according to claim 29, characterized in that the coating layer comprises an amorphous polylactic polymer composition.

31. A method for coating paper according to claim 29, characterized in that the molten polylactic polymer composition is provided at a temperature between about 495 - and about 540 ° F.

32. A method for coating paper according to claim 29, characterized in that the extrusion coating is provided when processing the composition of polylactide polymer at a line speed of between about 300 ft / min and about 2000 ft / min.

33. A article of manufacture, characterized in that it comprises a coated paper product according to claim 2.

34. An article of manufacture according to claim 33, characterized in that the article is selected from the group consisting of boxes, cups, plates, butter wrappers, margarine wrappers, pet food sacks, pet food boxes, wraps for hamburgers, multilayer bags, bags for cut grass and meat wraps.