Cleaning composition for recirculation of plastics

Abstract

A detergent composition comprising a surfactant having a cloud point of 60 DEG C or more and a glycol ether having a hydrophilic-lipophilic balance (HLB) of from 6 to 10. The glycol ether has an HLB of less than 7.5 if the surfactant has a cloud point of greater than 90 DEG C, or the glycol ether has an HLB of greater than 8.5 if the surfactant has a cloud point of from 60 DEG C to less than 75 DEG C, or the glycol ether has an HLB of from 7 to 9 if the surfactant has a cloud point of from 75 DEG C to 90 DEG C.

Description

Background Art Technical Field

[0001] The present disclosure relates to cleaning compositions, and more particularly to cleaning compositions comprising materials useful for recycling plastics.

[0002] introduction

[0003] There is a growing market for the production and use of recycled plastics. The commercial production of recycled plastics is accomplished through mechanical recycling. Mechanical recycling involves grinding, washing and drying post-consumer plastics to produce clean plastic flakes that can be converted into new products. During the washing step, high temperature treatment of about 80°C, a washing solution consisting of additives (such as surfactants and / or detergents), and caustic soda must be used to remove contaminants. Of particular concern for removal is the adhesive used to label the bottles. The removal of adhesives and other contaminants is important because these contaminants may adversely affect the properties of the recycled plastic (i.e., haze, mechanical properties, etc.). At a minimum, the cleaning composition should remove 50% or more of the residual adhesive to make the recycled plastic usable.

[0004] In cleaning compositions utilizing surfactants, the cloud point of the surfactant should be within ±5°C of the target cleaning temperature for maximum detergency. If the cloud point of the surfactant is much higher or lower than the temperature at which it is used for cleaning, the surfactant loses its detergency ability. Complicating the cloud point and detergency issues is the fact that including caustic soda into a cleaning solution containing a surfactant tends to lower the cloud point of the surfactant. Unfortunately, the reduction in cloud point by caustic soda depends on the amount of caustic soda present and the type of surfactant, but does not decrease in a linear or predictable manner. Typical caustic soda concentrations in cleaning mixtures range from 1 wt % to 2 wt %. Therefore, cleaning compositions containing surfactants cannot be easily replaced between mechanical recycling operations using different amounts of caustic soda without costly and time-consuming reformulation or trial and error testing. In addition, simply replacing a higher cloud point surfactant to compensate for the reduced cloud point is undesirable because it may mean using a solid surfactant, which adds additional handling issues and provides worse detergency performance. It is desirable that the binder removal rate fluctuates by no more than 20% over a range of 1 wt % to 2 wt % caustic soda.

[0005] In view of the above, it is surprising to discover a cleaning composition that achieves a binder removal rate of 50% or greater and also exhibits a binder removal rate that does not fluctuate by more than 20% over a range of 1 wt % to 2 wt % caustic soda. Summary of the invention

[0006] The inventors of the present invention have surprisingly discovered a cleaning composition that achieves an adhesive removal rate of 50% or greater and also exhibits an adhesive removal rate that fluctuates no more than 20% over a range of 1 wt % to 2 wt % caustic soda. The inventors of the present application have discovered that the use of glycol ethers as co-solvents with surfactants provides enhanced performance for surfactants used with alkali metal salts. Specifically, the selection of the surfactant and glycol ether combination depends on the hydrophilic-lipophilic balance ("HLB") of the glycol ether and the cloud point of the surfactant. For example, if the surfactant has a cloud point of greater than 90°C to 105°C, the glycol ether has an HLB of less than 7, or if the surfactant has a cloud point of 60°C to less than 75°C, the glycol ether has an HLB of 7 to 9, or if the surfactant has a cloud point of 75°C to 90°C, the glycol ether has an HLB of greater than 9. Advantageously, utilizing the specific combination of surfactant cloud point and glycol ether HLB values ​​outlined above allows the cleaning composition to be substituted for a different cleaning mixture for recycled plastics without concern that the different alkali metal salt concentrations will affect the detergency of the cleaning composition. Furthermore, the use of a specific surfactant cloud point and glycol ether HLB combination avoids the use of solid surfactants and their associated handling issues in high temperature wash environments because the alkali metal salt cloud point depression is eliminated.

[0007] The present application is particularly suitable for providing cleaning compositions for washing polymeric materials.

[0008] According to a first feature of the present disclosure, a cleaning composition comprises a surfactant having a cloud point of 60°C or greater and a glycol ether having a hydrophilic-lipophilic balance (HLB) of 6 to 10, wherein if the surfactant has a cloud point greater than 90°C, the glycol ether has an HLB of less than 7.5, wherein if the surfactant has a cloud point of 60°C to less than 75°C, the glycol ether has an HLB greater than 8.5, wherein if the surfactant has a cloud point of 75°C to 90°C, the glycol ether has an HLB of 7 to 9.

[0009] According to a second feature of the present disclosure, the surfactant is nonionic.

[0010] According to a third feature of the present disclosure, the glycol ether is 25 to 75 wt % of the total weight of the cleaning composition, and the surfactant is 25 to 75 wt % of the total weight of the cleaning composition.

[0011] According to a fourth feature of the present disclosure, the surfactant has a cloud point of 60°C to less than 75°C, and the glycol ether has an HLB of 7 to 9.

[0012] According to a fifth feature of the present disclosure, the surfactant has a cloud point of 75° C. to 90° C., and the glycol ether has an HLB of greater than 9.

[0013] According to a sixth feature of the present disclosure, the surfactant has a cloud point of more than 90° C. to 105° C., and the glycol ether has an HLB of less than 7.

[0014] According to a seventh feature of the present disclosure, the glycol ether is selected from the group consisting of diethylene glycol monohexyl ether and tripropylene glycol mono-n-butyl ether.

[0015] According to the eighth feature of the present disclosure, the surfactant is a C 12 -C 15 Secondary alcohol.

[0016] According to a ninth feature of the present disclosure, the cleaning mixture includes 0.01 wt % to 2.00 wt % of the cleaning composition based on the total weight of the cleaning mixture, 0.01 wt % to 3.00 wt % of the alkali metal salt based on the total weight of the cleaning mixture, and water.

[0017] According to a tenth feature of the present disclosure, the cleaning method includes the steps of adding a polymer material to a cleaning mixture, and washing the polymer material in the cleaning mixture at a temperature of 60°C to 90°C. DETAILED DESCRIPTION

[0018] As used herein, the term "and / or," when used in a list of two or more items, means that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing components A, B, and / or C, the composition may contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0019] Unless otherwise stated, all ranges are inclusive.

[0020] Test methods refer to the most recent test methods as of the priority date of this document unless the date is expressed as a two-digit number with a hyphen in the test method number. Reference to a test method includes reference to both the testing association and the test method number. Test method organizations are referenced by one of the following abbreviations: ASTM refers to ASTM International (formerly the American Society for Testing and Materials); IEC refers to the International Electrotechnical Commission; EN refers to European Standards; DIN refers to the German Institute for Standardization; and ISO refers to the International Organization for Standardization.

[0021] As used herein, unless otherwise indicated, the term weight percent ("wt%") refers to the weight percent of a component based on the total weight of the polymer composition.

[0022] As used herein, a Chemical Abstracts Services Registry Number ("CAS#") means the unique numeric identifier most recently assigned to a chemical compound by Chemical Abstracts Services as of the priority date of this document.

[0023] Cleaning composition

[0024] The present disclosure relates to a cleaning composition. The cleaning composition comprises a surfactant and a glycol ether. As will be explained in more detail below, the surfactant has a cloud point of 60°C or greater, and the glycol ether has a hydrophilic-lipophilic balance (HLB) of 6 to 10. The combination of the surfactant and the glycol ether used in the cleaning composition is selected based on their cloud point and HLB, respectively. Specifically, if the surfactant has a cloud point greater than 90°C, the glycol ether has an HLB less than 7.5, if the surfactant has a cloud point of 60°C to less than 75°C, the glycol ether has an HLB greater than 8.5, and if the surfactant has a cloud point of 75°C to 90°C, the glycol ether has an HLB of 7 to 9. In some examples, the surfactant has a cloud point of 60°C to less than 75°C, and the glycol ether has an HLB of 7 to 9. In some examples, the surfactant has a cloud point of 75°C to 90°C, and the glycol ether has an HLB greater than 9. In some examples, the surfactant has a cloud point of greater than 90°C to 105°C, and the glycol ether has an HLB of less than 7.

[0025] Surfactants

[0026] The cleaning compositions include surfactants. As used herein, surfactants are compounds that reduce the surface tension (or interfacial tension) between two materials. Specifically, surfactants include hydrophobic moieties and hydrophilic moieties. The cleaning compositions may include surfactants of 25% by weight to 75% by weight based on the gross weight of the cleaning compositions. For example, the cleaning compositions may include surfactants of 25% by weight or more, or 30% by weight or more, or 35% by weight or more, or 40% by weight or more, or 45% by weight or more, or 50% by weight or more, or 55% by weight or more, or 60% by weight or more, or 65% by weight or more, or 70% by weight or more, and 75% by weight or less, or 70% by weight or less, or 65% by weight or less, or 60% by weight or less, or 55% by weight or less, or 50% by weight or less, or 45% by weight or less, or 40% by weight or less, or 35% by weight or less, or 30% by weight or less.

[0027] The surfactant has a cloud point of 60°C or greater as measured according to ASTM D2024-09. Since cloud point measurements are unreliable above 100°C, the surfactant cloud point can be reported as >100°C, which indicates that the surfactant is not turbid at a temperature of 100°C or less. The surfactant can have a cloud point of 60°C or greater, or 62°C or greater, or 64°C or greater, or 66°C or greater, or 68°C or greater, or 70°C or greater, or 72°C or greater, or 74°C or greater, or 76°C or greater, or 78°C or greater, or 80°C or greater, or 82°C or greater, or 84°C or greater, or 86°C or greater, or 88°C or greater, or 90°C or greater, or 92°C or greater, or 94°C or greater, or 96°C or greater, or 98°C or greater, or >100°C as measured according to ASTM D2024-09.

[0028] A variety of surfactant types can be used in cleaning compositions. For example, the surfactant can be C2-C 20 The surfactant may contain an average of 5 to 20 ethylene oxide and / or propylene oxide units. The surfactant may contain an aromatic or phenyl moiety. The surfactant may be ionic. The surfactant may be nonionic. In a specific example, the surfactant is a C with an average of 15 moles of ethylene oxide. 12 -C 15 Examples of commercially available surfactants include TERGITOL TM 15-S-9, TERGITOL TM 15-S-12, TERGITOL TM 15-S-15, TRITON TM X-100、TERGITOL TM 23-6.5, TRITON TM DF-16 and TRITON TM DF-20, all available from The Dow Chemical Company, Midland, Michigan.

[0029] Glycol Ether

[0030] The cleaning compositions include glycol ethers. As used herein, glycol ethers are alkyl ethers of ethylene glycol or propylene glycol. The cleaning compositions may include glycol ethers of 25% to 75% by weight based on the gross weight of the cleaning compositions. For example, the cleaning compositions may include glycol ethers of 25% by weight or more, or 30% by weight or more, or 35% by weight or more, or 40% by weight or more, or 45% by weight or more, or 50% by weight or more, or 55% by weight or more, or 60% by weight or more, or 65% by weight or more, or 70% by weight or more, and 75% by weight or less, or 70% by weight or less, or 65% by weight or less, or 60% by weight or less, or 55% by weight or less, or 50% by weight or less, or 45% by weight or less, or 40% by weight or less, or 35% by weight or less, or 30% by weight or less.

[0031] The glycol ether has an HLB of 6.0 to 10.0 as measured according to the Davis HLB test method described in more detail below. For example, the glycol ether can have an HLB of 6.0 or greater, or 6.2 or greater, or 6.4 or greater, or 6.6 or greater, or 6.8 or greater, or 7.0 or greater, or 7.2 or greater, or 7.4 or greater, or 7.6 or greater, or 7.8 or greater, or 8.0 or greater, or 8.2 or greater, or 8.4 or greater, or 8.6 or greater, or 8.8 or greater, or 9.0 or greater, or 9.2 or greater, or 9.4 or greater, or 9.6 or greater, as measured according to the Davis HLB test method described in more detail below. 6 or more, or 9.8 or more and HLB of 10.0 or less, or 9.8 or less, or 9.6 or less, or 9.4 or less, or 9.2 or less, or 9.0 or less, or 8.8 or less, or 8.6 or less, or 8.4 or less, or 8.2 or less, or 8.0 or less, or 7.8 or less, or 7.6 or less, or 7.4 or less, or 7.2 or less, or 7.0 or less, or 6.8 or less, or 6.6 or less, or 6.4 or less, or 6.2 or less.

[0032] A variety of glycol ethers can be used in the cleaning composition. For example, the glycol ethers can include ethylene glycol monohexyl ether, tripropylene glycol mono-n-butyl ether, diethylene glycol monohexyl ether, dipropylene glycol mono-n-butyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol dimethyl ether, propylene glycol phenyl ether, dipropylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monopropyl ether, ethylene glycol phenyl ether, diethylene glycol monobutyl ether, ethylene glycol monopropyl ether, diethylene glycol monophenyl ether, triethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monomethyl ether and / or other glycol ethers. Examples of commercially available glycol ethers that can be used in the cleaning composition include hexyl CELLOSOLVE TM 、DOWANOL TMTPnB, Hexylcarbitol TM 、DOWANOL TM DPnB、DOWANOL TM PnB, PROGLYDE TM DMM diol, DOWANOL TM PPh, DOWANOL TM DPnP, Butyl CELLOSOLVE TM 、DOWANOL TM PnP、DOWANOL TM Eph, Butyl Carbitol TM , Propyl CELLOSOLVE TM Solvent, DOWANOL TM DiEPh, butoxytriglycol, DOWANOL TM TPM、DOWANOL TM DPM, all available from The Dow Chemical Company, Midland, Michigan.

[0033] additive

[0034] The cleaning composition may include one or more additives. The cleaning composition may include 0 wt % to 20 wt % of each additive based on the total weight of the cleaning composition. For example, the cleaning composition may include 0 wt % or more, or 1 wt % or more, or 2 wt % or more, or 3 wt % or more, or 4 wt % or more, or 5 wt % or more, or 6 wt % or more, or 7 wt % or more, or 8 wt % or more, or 9 wt % or more, or 10 wt % or more, or 11 wt % or more, or 12 wt % or more, or 13 wt % or more, or 14 wt % or more, or 15 wt % or more, or 16 wt % or more, or 17 wt % or more, or 18 wt % or more, or 19 wt % or more. 9 % by weight or more, and at the same time 20 % by weight or less, or 19 % by weight or less, or 18 % by weight or less, or 17 % by weight or less, or 16 % by weight or less, or 15 % by weight or less, or 14 % by weight or less, or 13 % by weight or less, or 12 % by weight or less, or 11 % by weight or less, or 10 % by weight or less, or 9 % by weight or less, or 8 % by weight or less, or 7 % by weight or less, or 6 % by weight or less, or 5 % by weight or less, or 4 % by weight or less, or 3 % by weight or less, or 2 % by weight or less, or 1 % by weight or less of additive. The additive may comprise one or more diluents, such as water, propylene glycol and / or other diluents. The additive may comprise one or more water cosolvents, such as octenyl succinic acid. The additive may comprise one or more defoamers and / or wetting agents, such as surfactants or high molecular weight polyglycols. The additive may comprise one or more water-soluble acrylic copolymers. The additive may include one or more chelating agents such as ethylenediaminetetraacetic acid ("EDTA"), citric acid, potassium citrate, sodium citrate, tetrasodium EDTA, tetrasodium EDTA, tetrasodium EDTA, diammonium EDTA, tetrasodium EDTA, tetrasodium EDTA tetrahydrate, disodium EDTA tetrahydrate, EDTA, disodium EDTA dihydrate, disodium EDTA dihydrate, pentasodium diethylenetriaminepentaacetate, pentasodium diethylene-triaminepentaacetate, trisodium n-(hydroxyethyl)-ethylenediaminetriacetate, disodium n-(hydroxyethyl)-ethylenediaminetriacetate iron, EDTA, and combinations thereof.

[0035] Cleaning mixture

[0036] The present disclosure also relates to a cleaning mixture. The cleaning mixture is a mixture of a cleaning composition and an alkali metal salt. The alkali metal salt is selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, manganese hydroxide and / or a combination thereof. The cleaning mixture may include 0.01 wt % to 2.00 wt % of the cleaning composition based on the total weight of the cleaning mixture. For example, the cleaning mixture may include 0.01 wt % or more, or 0.25 wt % or more, or 0.50 wt % or more, or 0.75 wt % or more, or 1.00 wt % or more, or 1.25 wt % or more, or 1.50 wt % or more, or 1.75 wt % or more, and 2.00 wt % or less, or 1.75 wt % or less, or 1.50 wt % or less, or 1.25 wt % or less, or 1.00 wt % or less, or 0.75 wt % or less, or 0.50 wt % or less, or 0.25 wt % or less of the cleaning composition.

[0037] The cleaning mixture can include 0.01 wt. % to 3.00 wt. % of the alkali metal salt, based on the total weight of the cleaning mixture. For example, the cleaning mixture may contain 0.01 wt % or more, or 0.25 wt % or more, or 0.50 wt % or more, or 0.75 wt % or more, or 1.00 wt % or more, or 1.25 wt % or more, or 1.50 wt % or more, or 1.75 wt % or more, or 2.00 wt % or more, or 2.25 wt % or more, or 2.50 wt % or more, or 2.75 wt % or more, while 3.00 wt % or less, or 2.75 wt % or less, or 2.50 wt % or less, or 2.25 wt % or less, or 2.00 wt % or less, or 1.75 wt % or less, or 1.50 wt % or less, or 1.25 wt % or less, or 1.00 wt % or less, or 0.75 wt % or less, or 0.50 wt % or less, or 0.25 wt % or less of an alkali metal salt, based on the total weight of the cleaning mixture.

[0038] The balance of the cleaning composition may be water or other diluent.

[0039] Cleaning Methods

[0040] The present disclosure also relates to a cleaning method utilizing a cleaning mixture. The cleaning method of the present disclosure comprises the step of adding a polymeric material to the cleaning mixture. The polymeric material can be a thermoplastic recycled after consumption, such as polyethylene terephthalate, high density polyethylene, biaxially oriented polypropylene, etc. The polymeric material can be processed into flakes, fragments and / or pellets. The polymeric material may be contaminated by adhesives, food waste, dust and other dirt.

[0041] The cleaning method also includes the step of washing the polymer material in a cleaning mixture at a temperature of 60° C. to 90° C. The cleaning mixture can be at 60° C. or higher, or 65° C. or higher, or 70° C. or higher, or 75° C. or higher, or 80° C. or higher, or 85° C. or higher, while at 90° C. or lower, or 85° C. or lower, or 80° C. or lower, or 75° C. or lower, or 70° C. or lower, or 65° C. or lower. The step of washing the polymer material can include stirring, mixing, agitating and / or ultrasonically vibrating the cleaning mixture. Mechanical scrubbing of the polymer material can also be utilized in the step of washing the polymer material.

[0042] The cleaning method removes adhesive present on the polymeric material. The cleaning method removes a certain percentage of adhesive present on the polymeric material. For example, the adhesive removal rate from the polymeric material completed by the cleaning method can be 50% or greater, or 55% or greater, or 60% or greater, or 65% or greater, or 70% or greater, or 75% or greater, or 80% or greater, or 85% or greater, or 90% or greater, or 95% or greater, or 100%.

[0043] The cleaning method can use a cleaning mixture having a range of alkali metal salt concentrations. Within a cleaning mixture alkali metal salt concentration of 1 wt % to 2 wt %, the adhesive removal ability of the cleaning mixture and method varies by 20% or less, as measured between the highest adhesive removal rate value and the lowest adhesive removal rate value obtained within the range.

[0044] Example

[0045] Material

[0046] Materials used in these examples are provided in Table 1. All materials were sourced from The Dow Chemical Company, Midland, Michigan.

[0047] Table 1

[0048]

[0049]

[0050] Table 2 provides a description of the materials used in these examples.

[0051] Table 2

[0052] Adhesive Type name type source Adhesive 1 PHL-4150-ZP Styrene PSA HB Fuller Adhesive 2 HM 8535 Styrene PSA Warren / Heigl Adhesive 3 <![CDATA[ROBOND TM PS-8915M]]> Acrylic PSA The Dow Chemical Company Adhesive 4 <![CDATA[ROBOND TM PS-7874K]]> Acrylic PSA The Dow Chemical Company

[0053] Test Method

[0054] Davis HLB: Hydrophile-lipophile balance (HLB) values ​​are calculated using the Davis group contribution method (JT Davis, EK Rideal, Interfacial Phenomena, Academic Press, New York, 1961, p. 371). This method assumes that the HLB value is given by the following formula:

[0055] HLB=7+∑(G i *N i )

[0056] G i represents the group contribution of different hydrophilic and lipophilic groups in the molecule, and N i represents how many times this particular group is present in the molecule. Table 3 shows the different hydrophilic and lipophilic groups considered for these calculations and their group contributions.

[0057] Table 3

[0058] Hydrophilic and lipophilic groups <![CDATA[Group contribution (G i )]]> Hydroxyl 1.9 Ether oxygen 1.3 alkyl -0.475 Ethylene oxide 0.35 Propylene oxide -0.125 Phenyl -1.662 ester 2.4

[0059] Cloud Point: Cloud point was measured according to ASTM D2024-09.

[0060] Sample preparation

[0061] Polyethylene terephthalate ("PET") (obtained from ePlastics, San Diego, California, USA) and biaxially oriented polypropylene (obtained from Multi Plastics Inc., Lewis Center, Ohio, USA) substrates were coated into thin films with either an acrylic pressure-sensitive adhesive or a styrene pressure-sensitive adhesive. The styrene adhesive was applied to the substrate using an HLCL-1000 hot melt coater laminator from Cheminstruments, and the acrylic adhesive was applied to the substrate using a knife coater. Next, some samples were laminated with a silicone-coated release liner to protect the adhesive film, while other samples were laminated with a BOPP film. After coating, each sample was allowed to cure for at least 48 hours before use. After curing, the samples were hand cut into 7.62 cm x 3.81 cm pieces, with each sample having a nominal loading of about 15 to 20 grams of adhesive per square meter or GSM (about 40 to 50 mg / sample). The silicon-coated release liner was removed directly prior to the washing experiment to prevent dust from accumulating on the coated surface.

[0062] In the case of the BOPP laminated samples, the PET was laminated with a 1.9 mm thick BOPP film instead of a silicon coated release liner. These samples were cut into approximately 1 cm x 1 cm squares and then added to the cleaning mixture.

[0063] After sample preparation and curing, 800 g of each of the present cleaning mixtures or comparative cleaning mixtures were preheated to about 70° C. in a 1 L Pyrex bottle. The solution typically included: 0.5 wt % to 2 wt % of a 40 wt % NaOH aqueous solution (as indicated), 0.05 wt % to 1 wt % of a cleaning composition, and water. After preheating, the solution was poured into a 1 L beaker and then further heated to 80° C. while stirring. Once the desired temperature was reached, the substrate sample was washed for 8 minutes at a stirring rate of 500 revolutions per minute. For each example, the sample was washed in triplicate with a blank (no adhesive), for a total of four samples per beaker.

[0064] After the washing step, the samples were rinsed in a beaker containing 500 mL of deionized water at 21°C for 3 minutes using an agitation speed of 400 rpm.

[0065] After rinsing, the samples were laid flat in metal trays and dried at high convection for about 16 hours at a temperature of 40° C. to 45° C. The next day, the samples were allowed to fully reach a temperature of about 23° C. before being weighed.

[0066] The BOPP laminate samples were washed in a similar manner; however, in this case, only 40 grams of sheet were washed in 400 grams of solution. All of the following steps were performed identically.

[0067] The adhesive removal rate was quantified using Equation 1:

[0068]

[0069] Where w1 is the weight of the substrate without adhesive, w2 is the weight of the substrate with adhesive, and w3 is the weight of the substrate after washing, rinsing, and drying. The adhesive removal rate is reported along with potential measurement errors. It should be noted that adhesive removal percentages exceeding 100% are the result of additional contaminants adhering to the test substrate.

[0070] result

[0071] Table 4 provides the results of the inventive examples ("IE") and comparative examples ("CE"). Specifically, the results of Table 3 were obtained under the following test conditions: the substrate was PET, the NaOH dosage was 1 wt%, the temperature was 80°C, the wash additive was 50 wt% of the indicated surfactant and 50 wt% of the indicated glycol ether, the binder type was Type 1, and the balance of the cleaning mixture used was water.

[0072] Table 4

[0073]

[0074]

[0075] As can be seen from Table 4, when the NaOH concentration is held constant, the embodiments of the present invention are able to provide adhesive removal rates greater than 50%. Although IE1 is technically below the 50% cutoff range, the measurement error of 10.25% indicates that the true value may be higher than 50%. It is worth noting that IE1 exhibits an improvement of about 13% relative to CE2. Although CE5-CE15 are able to achieve adhesive removal rates of 50% or better, it is believed that the absence of glycol ethers or the absence of a specified surfactant cloud point and glycol ether HLB relationship means that changes in NaOH concentration will have a negative and unpredictable impact on adhesive removal rates.

[0076] Table 5 demonstrates the ability of the embodiments of the present invention to maintain cleaning performance over a range of NaOH concentrations. The experiments in Table 5 were conducted under the following conditions: the substrate was PET, the temperature was 80°C, the detergent additive was 50 wt% of the indicated surfactant and 50 wt% of the indicated glycol ether, the binder type was Type 1, and the balance of the cleaning mixture used was water.

[0077] Table 5

[0078]

[0079] Table 5 demonstrates that for NaOH concentrations of 1 wt % to 2 wt %, including an appropriate glycol ether and a surfactant having a higher than necessary cloud point (i.e., a cloud point above the wash temperature) can impart good adhesive removal performance over the NaOH concentration range for the material without requiring a formulation change. Specifically, IE16 exhibits only about a 10% change over the NaOH concentration range of 1 wt % to 2 wt %. As shown, CE16 exhibits an adhesive removal rate of greater than 20% when NaOH is varied from 1 wt % to 2 wt %, which is undesirable. It is believed that if the cleaning composition has a glycol ether (a glycol ether having an HLB of less than 7.5 if the surfactant has a cloud point of greater than 90° C., or a glycol ether having an HLB of greater than 8.5 if the surfactant has a cloud point of 60° C. to less than 75° C., or a glycol ether having an HLB of 7 to 9 if the surfactant has a cloud point of 75° C. to 90° C.), then other cleaning compositions will exhibit less than a 20% change in adhesive removal over the defined NaOH range.

[0080] Table 6 demonstrates the ability of the embodiments of the present invention to maintain cleaning performance at various glycol ether to surfactant weight ratios. The experiments in Table 6 were conducted under the following conditions: the substrate was PET, the cleaning composition dosage was 0.2 wt%, the NaOH concentration was 1 wt%, the temperature was 80°C, the adhesive type was Type 1, and the balance of the cleaning mixture used was water.

[0081] Table 6

[0082]

[0083]

[0084] Table 7 demonstrates the ability of the embodiments of the present invention to maintain adhesive removal at various cleaning composition concentrations in the cleaning mixture. The experiments in Table 7 were conducted under the following conditions: the substrate was PET, the NaOH concentration was 1 wt%, the weight ratio of glycol ether to surfactant was 1:1, the temperature was 80°C, the adhesive type was Type 1, and the balance of the cleaning mixture used was water.

[0085] Table 7

[0086] Ex. Surfactants Glycol Ether Cleaning composition (wt%) Adhesive removal rate % IE20 <![CDATA[TERGITOL TM 15-S-15]]> <![CDATA[Hexyl carbitol TM > 1.0 81.77±18.08％ IE21 <![CDATA[TERGITOL TM 15-S-15]]> <![CDATA[Hexyl carbitol TM > 0.5 100.67±0.58％ IE22 <![CDATA[TERGITOL TM 15-S-15]]> <![CDATA[Hexyl Carbitol TM > 0.2 93.13±13.1％ IE23 <![CDATA[TERGITOL TM 15-S-15]]> <![CDATA[Hexyl Carbitol TM > 0.15 92.1％±12.6％ IE24 <![CDATA[TERGITOL TM 15-S-15]]> <![CDATA[Hexyl carbitol TM > 0.05 56.60±13.77％

Claims

1. A cleaning composition, comprising: a surfactant having a cloud point of 60° C. or greater; and A glycol ether having a hydrophile-lipophile balance (HLB) of 6 to 10, Wherein if the surfactant has a cloud point greater than 90°C, the glycol ether has an HLB less than 7.5, wherein if the surfactant has a cloud point of 60°C to less than 75°C, the glycol ether has an HLB greater than 8.5, wherein if the surfactant has a cloud point of 75°C to 90°C, the glycol ether has an HLB of 7 to 9.

2. The cleaning composition of claim 1, wherein the surfactant is nonionic.

3. The cleaning composition according to any one of claims 1 and 2, wherein the glycol ether is 25 to 75 wt% of the total weight of the cleaning composition, and the surfactant is 25 to 75 wt% of the total weight of the cleaning composition.

4. The cleaning composition of any one of claims 1 to 3, wherein the surfactant has a cloud point of 60°C to less than 75°C, and the glycol ether has an HLB of 7 to 9.

5. The cleaning composition of any one of claims 1 to 3, wherein the surfactant has a cloud point of 75°C to 90°C and the glycol ether has an HLB greater than 9.

6. The cleaning composition of any one of claims 1 to 3, wherein the surfactant has a cloud point of greater than 90°C to 105°C and the glycol ether has an HLB of less than 7.

7. The cleaning composition according to claim 6, wherein the glycol ether is selected from the group consisting of diethylene glycol monohexyl ether and tripropylene glycol mono-n-butyl ether.

8. The cleaning composition according to claim 7, wherein the surfactant is a C 12 -C 15 Secondary alcohol.

9. A cleaning mixture, comprising: 0.01 wt % to 2.00 wt % of the cleaning composition according to any one of claims 1 to 8, based on the total weight of the cleaning mixture; 0.01 wt. % to 3.00 wt. % of an alkali metal salt, based on the total weight of the cleaning mixture; and water.

10. A cleaning method, comprising the following steps: Adding a polymer material to the cleaning mixture of claim 9; as well as The polymeric material is washed in the cleaning mixture at a temperature of 60°C to 90°C.

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