Resin packaging

Abstract

This invention relates to packages, systems, and methods for protecting rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins suitable for use in the production of printing inks and other coatings from the effects of exposure to oxygen during transport and storage. In particular, this method involves the packaging of rosin-based resins, modified rosin resins, hydrocarbon resins and/or hydrocarbon modified resins at a temperature at least 5° F. below the glass transition temperature of the resin being packaged in sealed oxygen-transmission resistant enclosures from which a substantial portion of the oxygen has been evacuated.

Description

FIELD OF INVENTION

This invention relates to packages, systems, and methods for protecting rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins suitable for use in the production of printing inks and other coatings from the effects of exposure to oxygen during transport and storage. In particular, this method involves the packaging of rosin-based resins, modified rosin resins, hydrocarbon resins and/or hydrocarbon modified resins at a temperature at least 5° F. below the glass transition temperature of the resin being packaged in sealed oxygen-transmission resistant enclosures from which a substantial portion of the oxygen has been evacuated.

BACKGROUND OF THE INVENTION

It is well known that rosin exists in a number of forms. The term rosin, as used herein, includes tall oil rosin, wood rosin, gum rosin, crude materials and mixtures containing any of the foregoing, and, in general, any materials containing abietic acid, including tall oil fractions containing various proportions of rosin and fatty acids. Hydrocarbon resins refer to products produced using materials such as dicyclopentadiene, cyclopentadiene, indene, vinyl toluene, and the like, which are derived from distillation of crude oil or natural gas. Rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins are chemically modified and polymerized to produce products having from low to very high molecular weights based on the required physical properties of the end user.

Rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins are commonly employed in a variety of different uses, including lithographic inks and other printing ink formulations, coating formulations, pigment resinating, dry grinding of pigments and presscake flushing operations. However, a major problem exists in the industry concerning the transport and storage of these resins. Rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins are capable of reacting with molecular oxygen in a process known as autoxidation. These resins are particularly susceptible to such reactions due to the existence of double bonds throughout the resins. Autoxidation is essentially a free radical process that can be initiated by heat. Free radicals are formed in the resin, which can react with molecular oxygen to form peroxy radicals. These peroxy radicals can further react with other organic material to form hydroperoxides. Hydroperoxides tend to be stable at temperatures of less than 70° F., but can decompose at higher temperatures to generate additional free radicals and continue to fuel the oxidation process.

The oxidation and peroxide formation are undesirable processes that can alter the physical properties of the rosin-based resins and modified rosin resins to such an extent that the resins are not longer suitable for employment in the formulation of inks or coatings, or for various other uses. Oxidation and peroxide formation can increase the viscosity of these resins, thereby making them less soluble—or even insoluble—in ink oils. Furthermore, oxidized resins are more prone to absorb moisture, which can be a major problem for coating producers. For example, should a coating producer attempt to dissolve oxidized resin in a hot ink oil system, the presence of excessive moisture can cause the varnish to foam, thereby causing production and safety concerns.

It is common practice in the industry to flake rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins to facilitate their transportation and use in the production of inks and coatings. The flaking of these resins provides optimal conditions for oxidation and peroxide formation, as the flaked resins tend to have relatively large surface areas exposed to oxygen interaction.

Flaked rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins are commonly packaged in large containers (such as sacks containing from 50 to 2,500 pounds of resin and other packages) for transportation and storage. The problems of oxidation and peroxide formation in packaged rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins can be particularly acute during the summer months and during extended periods of transportation and/or storage.

Various methods have been utilized in attempts to deal with the problem of oxidation and peroxide formation in packaged rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins. One approach has been to keep the resins as cool as possible by maintaining the packaged resins under temperature-controlled conditions during transportation and storage. However, the use of air-conditioned transportation or warehousing can be comparatively expensive.

Another approach has been to place the rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins directly into solution. However, pre-made resin solutions may restrict the user's flexibility to formulate inks and other coatings.

Yet another approach to the problem of oxidation and peroxide formation has been to add antioxidants to the packaged rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins to disrupt the free radical process. For example, hindered phenol antioxidants can be added to react with the peroxy radicals to form inactive species. Likewise, phosphites and thioethers can be added to react with hydroperoxides to yield non-reactive products. Often these two classes of antioxidants are employed together to achieve a synergistic effect. Such antioxidants are typically added to rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins at a rate of about 0.1% to about 2.0% on a weight basis. However, the use of such antioxidants is relatively expensive.

Therefore, an object of this invention is to solve these major problems by disclosing a method of packaging rosin-based resins, modified rosin resins, hydrocarbon resins and/or hydrocarbon modified resins having a temperature at least 5° F. below the glass transition temperature of the resin being packaged in sealed oxygen-transmission resistant enclosures from which a substantial portion of the oxygen has been evacuated.

Another object of this invention is to disclose packages for rosin-based resins, modified rosin resins, hydrocarbon resins and/or hydrocarbon modified resins used in the production of lithographic printing inks and other coatings.

A further object of this invention is to disclose a system for packaging rosin-based resins, modified rosin resins, hydrocarbon resins and/or hydrocarbon modified resins used in the production of inks and other coatings.

SUMMARY OF THE INVENTION

The present invention achieves these objects and others by the packaging of rosin-based resins, modified rosin resins, hydrocarbon resins and/or hydrocarbon modified resins having a temperature at least 5° F. below the glass transition temperature of the resin being packaged in sealed oxygen-transmission resistant enclosures from which a substantial portion of the oxygen has been evacuated. It has been found that the packaging of rosin-based resins, modified rosin resins, hydrocarbon resins and/or hydrocarbon modified resins in an oxygen-reduced atmosphere while they are at a temperature at least 5° F. below their glass transition temperatures serves to prevent accelerated oxidation. Energy in the form of heat is generated during oxidation. By allowing additional energy in the form of temperatures greater than about at least 5° F. below the glass transition temperature of the resin, it is possible to accelerate the oxidation process utilizing the trapped air within flaked resin (that is generated during the flaking process) and heat energy that releases the trapped air. Because the glass transition temperatures of rosin-based resins and modified rosin resins are commonly in the range of about 120° F. to about 200° F., air trapped within the thin resin flakes can be released as the temperature approaches the glass transition temperature of the resin. Also, any moisture that is present within the package can have the effect of distributing heat in a more even fashion, while also evenly distributing free radicals formed during oxidation and continuing the progress to hydroperoxide formation. This process continues until the fuel sources in resin flakes have been consumed. In some cases, the initial temperature and heat energy generated approaches temperatures where esterfication (i.e., the chemical reaction commonly used to produce rosin-based resins and hydrocarbon resins) begins. In these extreme situations, the resins can become molten and potentially exothermic (thereby generating water-formation and increasing the molecular weight of the resins in an uncontrolled fashion).

Packaging the rosin-based resins, modified rosin resins, hydrocarbon resins and/or hydrocarbon modified resins in sealed oxygen-transmission resistant enclosures from which a substantial portion of the oxygen has been evacuated serves to retard the oxidation process. Another further advantage of vacuum sealing under pressure is that the compression of the brittle resin flakes can shatter the thin layers of resin that trap air with individual flakes, thereby freeing trapped air for evacuation. Additionally, vacuum sealing also serves to evacuate moisture that may be present on the surface of flaked resin, thus helping to reduce distribution of heat energy.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The method of the present invention comprises packaging at least one member selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins, hydrocarbon modified resins, and combinations thereof at a temperature at least 5° F. below the glass transition temperature of said resin in sealed oxygen-transmission resistant enclosures from which a substantial portion of the oxygen has been evacuated.

A further embodiment of the present invention comprises a method for packaging resin, comprising the steps of:

• • 1) providing resin selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins, hydrocarbon modified resins and combinations thereof;
  • 2) placing the resin in one or more oxygen-transmission resistant, flexible packaging enclosures wherein each enclosure has at least one sealable opening therein;
  • 3) subjecting the packaging enclosures and the resin to a vacuum force to remove a substantial portion of the oxygen from the packaging enclosures;
  • 4) sealing the flexible packaging enclosures while subjected to the vacuum force such that upon sealing the packaging enclosure contains an oxygen-reduced atmosphere, and wherein the resin has a temperature at least 5° F. below its glass transition temperature at the time of sealing.

In another embodiment, at least one member selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins, hydrocarbon modified resins and combinations thereof having a temperature at least 5° F. below the glass transition temperature of the resin is placed within one or more oxygen-transmission resistant, flexible packages. Each package has at least one sealable opening therein. The packages and the resins are then subjected to a vacuum force. The vacuum force is maintained for a time sufficient to remove a substantial portion of the oxygen from the package. While under the influence of the vacuum, the packages are sealed while maintaining the resin temperature and the vacuum force, rendering the package gas impermeable while maintaining an oxygen-reduced atmosphere inside the package. Typically, the package is heat sealed shortly after initiating the vacuum, and usually not more than one-half hour after initiating the vacuum.

In another embodiment, at least one member selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins, hydrocarbon modified resins and combinations thereof is placed within one or more containers (such as a sack or other package). The container(s) containing resin having a temperature at least 5° F. below the glass transition temperature of the resin is subsequently placed within one or more oxygen-transmission resistant, flexible packages wherein each package has at least one sealable opening therein. The packages, containers, and resin are then subjected to a vacuum force. The vacuum force is maintained for a time sufficient to remove a substantial portion of the oxygen from the package. While under the influence of the vacuum, the packages are sealed while maintaining the resin temperature and the vacuum force, rendering the package gas impermeable while maintaining an oxygen-reduced atmosphere inside the package. Typically, the package is heat sealed shortly after initiating the vacuum, and usually not more than one-half hour after initiating the vacuum.

In another embodiment, at least one member selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins, hydrocarbon modified resins and combinations thereof that are to be subjected to the method of the invention are first placed in an oxygen-transmission resistant flexible package that has at least one sealable opening therein. The package and the resin are then subjected to a vacuum force while at least one sealable opening remains open. The vacuum force is maintained for a time sufficient to remove a substantial portion of the oxygen from the package. Thereafter, the package is sealed (preferably heat sealed) while the resin has a temperature at least 5° F. below the glass transition temperature of the resin and while maintaining the vacuum force, rendering the package gas impermeable while maintaining an oxygen-reduced atmosphere inside the package.

The package of the present invention comprises a sealed, oxygen-transmission resistant enclosure surrounding at least one member selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins, hydrocarbon modified resins and combinations thereof, wherein said resin has a temperature at least 5° F. below the glass transition temperature of the resin at the time the enclosure is sealed and wherein said package had a substantial portion of the oxygen evacuated from said package at the time the enclosure is sealed to produce an oxygen-reduced atmosphere in said package. Where desired, more than one oxygen-transmission resistant enclosure may be employed.

The system of the present invention for packaging at least one member selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins, hydrocarbon modified resins and combinations thereof comprises:

• • (a) means for forming a sealed, oxygen-transmission resistant enclosure around said resin, and
  • (b) means for evacuating a substantial portion of the oxygen from said enclosure prior to sealing of said enclosure to produce an oxygen-reduced atmosphere within said enclosure at a time when said resin has a temperature at least 5° F. below the glass transition temperature of said resin.
    Where desired, more than one oxygen-transmission resistant enclosure may be employed.

Enclosures which are suitable for this method are oxygen-transmission resistant. It is preferred that the oxygen-transmission resistant enclosures have an oxygen transmission rate (OTR) of less than about 200 (preferably less than about 100 and more preferably less than about 50) cubic centimeters per square meter per day at atmospheric pressure and a moisture vapor transmission rate (MVTR) of less than about 90 (preferably less than about 50 and more preferably less than about 15) grams per square meter per day at atmospheric pressure. Suitable types of enclosures include, but are not limited to, the following: bags, sheets, liners, metal containers, composite containers, and the like. Packaging materials that are suitable for use in the enclosure within which the rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins are sealed can be selected from among the many types of high barrier, oxygen transmission resistant, packaging materials. Such packaging materials include, but are not limited to, the following: nylons, polyethylenes, foils, plastics, EVOH, composite materials, and combinations thereof. The thickness of the packaging material is preferably in the range of about 4 millimeters to about 50 millimeters.

It is preferred that the oxygen-transmission resistant enclosure be a heat sealable bag. The type of bag or other enclosure used to package the resin is chosen based on the characteristics of the resin product being packaged and the desired use of the package. It is well within the ability of one skilled in the art to determine the type of enclosure to be employed for desired package uses.

It is further preferred that the enclosure employed in the sealing process be a 4.5 millimeter nylon and polyethylene fused layered liner. The nylon characteristics include a very low OTR of 30-50 cubic centimeters per square meter per day at atmospheric pressure, an MVTR of 5-15 grams per square meter per day, and the formability to allow the enclosure to conform to the shape of the original bulk sack or other container. The polyethylene characteristics include a very low MVTR and low OTR, good formability properties, and excellent sealability. The polyethylene layer is a lower cost barrier material that provides thickness for durability. Durability of packaging is important as resin packages are commonly transported to customers by truck and handled multiple times until opened and used by customers. During handling, it is important to provide a durable package to withstand handling and transportation while maintaining an oxygen-reduced atmosphere within the package.

It is further preferred that the rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins be first packaged in a sack or other container prior to enclosure in the oxygen-transmission resistant enclosure. The sack is then sealed in the enclosure from which a substantial portion of the oxygen has been evacuated. At the time the enclosure is sealed to produce an oxygen-reduced atmosphere within the enclosure, the resin(s) contained in the enclosure should have a temperature at least 5° F. below the glass transition temperature of the resin(s).

The method or means by which the oxygen is evacuated from the enclosure to produce an oxygen-reduced atmosphere is not critical, in that the oxygen may be evacuated in any suitable manner that does not adversely effect the OTR and MTVR characteristics of the enclosure or the chemical characteristics of the rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins. Suitable methods include, but are not limited to, the following: purging with at least one inert gas (such as nitrogen, argon, helium, neon, etc.), vacuum sealing, and the like. It is preferred to maintain a vacuum force to remove a substantial portion of the oxygen while sealing the enclosure, thereby rendering it impermeable to gases.

As used herein, the removal of a “substantial portion of the oxygen” is the removal of an amount of oxygen sufficient to impede oxidation of the rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins. It is preferred to remove substantially all of the oxygen from the enclosure, and it is further preferred to remove all of the oxygen from the enclosure.

A preferred method of oxygen evacuation is a combination of inert gas purging and vacuum sealing. It is further preferred to employ at least one sack (or other container) to contain the rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins. The sack(s) containing the rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins is placed within an enclosure (preferably a heat sealable bag), then subjected to a first purge with inert gas (preferably nitrogen) to displace and dilute the oxygen content. The gas is then vacuumed out of the enclosure bag to 6.93 pounds per square inch gage. The enclosure bag is purged a second time with inert gas (preferably nitrogen) to further dilute any remaining oxygen and a second vacuum is pulled to 6.93 pounds per square inch gage vacuum. The enclosure is then sealed to maintain the oxygen-reduced atmosphere within the enclosure. At the time the enclosure is sealed, the resins contained in the enclosure have a temperature at least 5° F. below their glass transition temperatures.

Rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins which are suitable for use in the production of lithographic inks, printing inks, coatings, pigment resinating, dry grinding of pigment and/or presscake flushing operations may be used in the present invention. Suitable modified rosin resins include, but are not limited to, the following: maleic-modified rosin resins, phenolic-modified rosin resins, fumaric-modified rosin resins and the like. It is preferred that the rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins be flaked prior to packaging within the oxygen oxygen-transmission resistant enclosure.

It is critical that the temperature of the rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins be at least 5° F. below the glass transition temperature of the resin being packaged at the time the enclosure is sealed. If more than one resin is being packaged in the enclosure, then the temperature of the resins being packaged at the time the enclosure is sealed should be at least 5° F. below the lowest of the glass transition temperatures of the packaged resins. It is preferred that the temperature of the resin be less than about 100° F. at the time the enclosure is sealed, more preferably less than about 80° F., and more preferably less than about 70° F.

It has been found that the packaging of the rosin-based resins, modified rosin resins, hydrocarbon resins, and/or hydrocarbon modified resins in an oxygen-reduced atmosphere while they are at a temperature at least 5° F. below their respective glass transition temperatures serves to prevent accelerated oxidation. Energy in the form of heat is generated during oxidation. By allowing additional energy in the form of temperatures near or at the glass transition temperature of the resin, it is possible to accelerate the oxidation process utilizing the trapped air within flaked resin (that is generated during the flaking process) and heat energy that releases the trapped air. Because the glass transition temperatures of rosin-based resins and modified rosin resins are commonly in the range of about 120° F. to about 200° F., air trapped within the thin resin flakes can be released as the temperature approaches the glass transition temperature of the resin. Also, any moisture that is present within the package can have the effect of distributing heat in a more even fashion, while also evenly distributing free radicals formed during oxidation and continuing the progress to hydroperoxide formation. This process continues until the fuel sources in the resin flakes have been consumed. As a function of this process, it has been determined that vacuum sealing is most effective at temperatures lower than about 70° F. and at relative humidities lower than about 60%. It is preferred that the relative humidity be as low as possible. One skilled in the art would recognize that barrier materials can also change with these process conditions and become a contributing factor in the OTR and MVTR rates. Likewise, OTR and MVTR rates increase with elevated temperatures and higher humidities.

The following examples are provided to further illustrate the present invention and are not to be construed as limiting the invention in any manner.

EXAMPLE 1

A series of tests were conducted evaluating the effect of packaging and storage on the oxidation, viscosity, and dilution characteristics of hard resins. For comparison purposes, samples of HC-910 (a flaked hydrocarbon modified rosin resin having a glass transition temperature of 82.2° C. commercially available from MeadWestvaco Corporation) were evaluated under two conditions. As a control, 500 grams of resin was placed in a tray and left exposed to atmosphere (hereinafter “tray” sample). In the second evaluation, 100 grams of resin were placed in each of sixteen separate polyethylene plastic bags, vacuum was applied to remove a substantial proportion of the air out of the bag, and the bags were then heat sealed to form sealed enclosures having oxygen-reduced atmospheres (hereinafter “vacuum bag” samples). The resins were packaged at a temperature of about 73° F. and a relative humidity of about 30%. The respective resin samples were subsequently stored at 110° F. to simulate typical summertime warehouse conditions.

The evaluations were based on a run of two samples per week over a 52-day period. The tests run on each sample throughout the testing period were 1:2 ARLO solution line-to-line seconds viscosity, % M-47 dilution, and a cloud point determination using the Chemtronic I with 10% resin and 90% PKWF®6/9 Test oil (a test oil commercially available from Haltermann GmbH). The 1:2 ARLO test is a standard industry related test (ASTMD 1725-62, American Society for Testing and Materials), where 1 part of resin is added to 2 parts of ARLO (alkaline refined linseed oil) heated to 215° C. The solution is then added to a viscosity tube (bubble tube), controlled to 25° C., and the viscosity is measured as an air bubble travels the length of the tube (with the viscosity recorded in seconds). The prepared solution is also titrated with MagieSol® 47 (a distilled mineral oil commercially available from Magie Bros.) and recorded in percentage of oil added to prepared ARLO solution, which is also a standard industry related test (ASTMD 5062-96). The cloud point test employed a Chemotronic Automatic Cloud Point Tester, wherein a solution of resin and ink oil is heated at a controlled rate to 230° C. with stirring, then cooled at a controlled rate, to record the point of resin kick out (cloud point) using a photo electric sensor. The resins initially had a 1:2 ARLO solution line-to-line seconds viscosity of 130 seconds, a % M-47 dilution of 141%, and a cloud point determination of 129° C. The test results are shown in Table I below.

TABLE I
RESIN PACKAGING
Day #	Sample	V1:2 (sec.)1	% M-47 Dil.2	Cld Point (° C.)3
3	Tray	138	125	138
	Vacuum Bag	134	136	126
10	Tray	176	121	155
	Vacuum Bag	143	127	130
14	Tray	190	105	143
	Vacuum Bag	129	152	129
17	Tray	209	99	162
	Vacuum Bag	136	137	129
21	Tray	357	86	141
	Vacuum Bag	132	133	124
25	Tray	308	77	208
	Vacuum Bag	168	128	131
29	Tray	Insoluble	Insoluble	147
	Vacuum Bag	155	117	129
35	Tray	Insoluble	Insoluble	190
	Vacuum Bag	155	137	135
38	Tray	Insoluble	Insoluble	191
	Vacuum Bag	141	126	131
42	Tray	Insoluble	Insoluble	Insoluble
	Vacuum Bag	136	126	135
49	Tray	Insoluble	Insoluble	210
	Vacuum Bag	174	118	129
52	Tray	Insoluble	Insoluble	Insoluble
	Vacuum Bag	176	114	132
1V1:2 (sec) = 1:2 ARLO solution line-to-line viscosities.
2% M-47 Dil. = % M-47 dilution.
3Cld Point = cloud point determination in ° C. using a Chemtronic I with 10% resin and 90% PKWF 6/9 Test oil.

The viscosity results in Table I show the atmospheric sample going out of specification (i.e., 135-195 line to line seconds) at day 21 of testing and insoluble at day 35. In contrast, the vacuum bag samples stayed in specification over the entire period with only a slight increasing trend in viscosity.

Dilution results show a larger negative sloping trend on the atmospheric sample. The atmospheric sample is out of specification (i.e., % M-47 dilution of 130-180%) low in dilution at day 7 of testing, and insoluble at day 29. Dilutions on the vacuum bag samples were able to stay in specification until day 21. At no time did the vacuum bag samples fall below 110% M-47 dilution level (which is extremely favorable).

Cloud point measurements for vacuum bag samples stayed constant throughout the testing period. In contrast, the atmospheric sample's cloud point rose at a steady rate with each test until the 38^th day when no cloud point could be obtained due to insolubility. The cloud point measurements of the atmospheric samples tended to vary somewhat due to the relative exposures to oxygen of the surface areas of the individual flakes.

EXAMPLE 2

A rosin resin can be packaged by the following method. Two thousand pounds of flaked hard rosin resin can be placed into a super sack. The super sack containing the resin can be placed within a nylon and polyethylene fused layered liner enclosure bag, which can then be subjected to a first purge with nitrogen to displace and dilute the oxygen content therein. The nitrogen gas can then vacuumed out of the enclosure bag to about 6.9 pounds per square inch gage. The enclosure bag can then purged a second time with nitrogen gas to further dilute any remaining oxygen and a second vacuum can be pulled to about 6.9 pounds per square inch gage to remove the gas and produce an oxygen-reduced atmosphere. The enclosure bag can then be sealed to maintain the oxygen-reduced atmosphere within the enclosure bag. At the time the enclosure bag is sealed, the resins contained in the enclosure bag have a temperature at least 5° F. below their glass transition temperatures.

Many modifications and variations of the present invention will be apparent to one of ordinary skill in the art in light of the above teachings. It is therefore understood that the scope of the invention is not to be limited by the foregoing description, but rather is to be defined by the claims appended hereto.

Claims

1. A method for packaging resin, comprising the steps of:

a) providing resin selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins, hydrocarbon modified resins, and combinations thereof;

b) placing said resin in one or more oxygen-transmission resistant, flexible packaging enclosures wherein each enclosure has at least one sealable opening therein;

c) subjecting the packaging enclosures and said resin to a vacuum force to remove a substantial portion of the oxygen from the packaging enclosures; and

d) sealing the flexible packaging enclosures while subjected to the vacuum force such that upon sealing the packaging enclosure contains an oxygen-reduced atmosphere, and wherein said resin has a temperature at least 5° F. below its glass transition temperature at the time of sealing.

2. The method of claim 1 wherein the resin is flaked.

3. The method of claim 1 wherein the resin has a temperature of less than about 100° F.

4. The method of claim 1 wherein the resin has a temperature of less than about 70° F.

5. The method of claim 1 wherein the packing enclosure has an oxygen transmission rate of less than about 200 cubic centimeters per square meter per day at atmospheric pressure.

6. The method of claim 1 wherein the packing enclosure has a moisture vapor transmission rate of less than about 90 grams per square meter per day at atmospheric pressure.

7. A package for resins comprising a sealed, oxygen-transmission resistant enclosure surrounding at least one resin selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins, hydrocarbon modified resins, and combinations thereof, wherein said resin has a temperature at least 5° F. below its glass transition temperature at the time the enclosure is sealed and wherein said package had a substantial portion of the oxygen evacuated from said package at the time the enclosure is sealed to produce an oxygen-reduced atmosphere in the package.

8. The package of claim 7 wherein the resin is flaked.

9. The package of claim 7 wherein the resin has a temperature of less than about I 00° F. at the time the enclosure is sealed.

10. The package of claim 7 wherein the resin has a temperature of less than about 70° F. at the time the enclosure is sealed.

11. The package of claim 7 wherein the enclosure has an oxygen transmission rate of less than about 200 cubic centimeters per square meter per day at atmospheric pressure.

12. The package of claim 7 wherein the enclosure has a moisture vapor transmission rate of less than about 90 grams per square meter per day at atmospheric pressure.

13. A system for packaging at least one resin selected from the group consisting of rosin-based resins, modified rosin resins, hydrocarbon resins and hydrocarbon modified resins and combinations thereof comprising:

a) means for forming a sealed, oxygen-transmission resistant enclosure around said resin, and

b) means for evacuating a substantial portion of the oxygen from said enclosure prior to sealing of said enclosure to produce an oxygen-reduced atmosphere within said enclosure at a time when the enclosed resin has a temperature at least 5° F. below its glass transition temperature.

14. The system of claim 13 wherein the resin is flaked.

15. The system of claim 13 wherein the resin has a temperature of less than about 1 00° F. at the time the enclosure is sealed.

16. The system of claim 13 wherein the resin has a temperature of less than about 70° F. at the time the enclosure is sealed.

17. The system of claim 13 wherein the enclosure has an oxygen transmission rate of less than about 200 cubic centimeters per square meter per day at atmospheric pressure.

18. The system of claim 13 wherein the enclosure has a moisture vapor transmission rate of less than about 90 grams per square meter per day at atmospheric pressure.