KR20040047892A - High solids content, low-viscosity emulsion polymers - Google Patents

Abstract

The present invention provides emulsion polymers useful in the manufacture of coatings and adhesives, including PSA tapes, labels, and other structures. The polymers of the present invention are characterized by high solids content and low viscosity. The present invention also provides a process for preparing the polymer. A plurality of acrylic monomers are copolymerized in the presence of a plurality of surfactants using the divided feedstock, and the resulting emulsion polymer has a bimodal or larger particle size distribution.

Description

Emulsion polymer with high solid content and low viscosity {HIGH SOLIDS CONTENT, LOW-VISCOSITY EMULSION POLYMERS}

Acrylic polymers are well known and commonly used in the manufacture of adhesives, labels, and other structures, including PSA tapes. Acrylic polymers are also used as various coatings, or coating additives, including paints, primers, barrier layers, anti-scratch hard coatings, ink soluble coatings, and chemical resistant coatings. Acrylic polymers can be prepared by various polymerization methods including bulk polymerization, solvent polymerization and emulsion polymerization. In emulsion polymerization, one or more emulsifiers (surfactants) are used as auxiliaries so that a certain number of monomers are dispersed in a continuous aqueous phase, and the polymerization reaction is, for example, a free-radical initiator. It is catalyzed by The resulting product, i.e., the colloidal dispersion of polymer particles, is called latex, emulsion polymer or simply emulsion. Particle size and molecular weight are generally distributed over a range of values and can be expressed using statistical means.

In the process of making PSA tapes and labels, it is desirable to use polymers having a relatively high solids content. Due to the relatively low moisture content of emulsion polymers with high solids content, a number of significant cost savings can be realized: More material can be formed in a given manufacturing cycle; Transportation costs are reduced; Faster line speeds are achieved because there is less moisture to remove when drying the polymer coating. At the same time, however, as the solids content of the polymer increases, the viscosity of the emulsion polymer generally increases. Too high a viscosity results in poor coatability and more difficult processing. For example, paste-like emulsions cannot be coated with Meyer rods and similar coating apparatus conventionally used in the manufacturing process of PSA tapes, labels, and other structures. Generally, the solids content of emulsion polymers used in the PSA industry rarely exceeds about 67% by weight. For economics, a viscous emulsion polymer having a high solid content and a low viscosity is required for processability.

PSA is used under a variety of temperature and environmental conditions in a wide variety of applications. Certain particular PSAs may exhibit good performance (adhesion) when applied to a given substrate or at a particular temperature, but may not be suitable for other substrates and other use temperatures. Particularly problematic is low temperature (<0 ° C) application. Even in order to achieve a nominal level of adhesion, the glass transition temperature (T _g ) of the PSA polymer is generally required to be much lower than the temperature of the adhesive, ie the temperature at which the PSA tape, label or other construct is applied or used on the substrate. Do. However, not all emulsion polymers with low T _g are suitable for use as PSA at low temperatures. It is not uncommon for polymers with low T _g to have undesirably high creep values such that switching (slitting, die cutting, matrix stripping, etc.) becomes a problem. Thus there is a need for an improved emulsion polymer that functions as a PSA when applied to various substrates even at low temperatures.

The present invention relates to emulsion polymers, in particular acrylic polymers useful as coatings and adhesives.

The inventors have found that acrylic emulsion polymers characterized by high solids content and low viscosity can be prepared using a mixture of surfactant and split monomer feed.

In one embodiment of the present invention, an emulsion having a high solid content and a low viscosity comprises an emulsified product copolymerized with a plurality of monomers in the presence of a plurality of surfactants, wherein the plurality of monomers are weights based on the total amount of the monomers. %, About 90% to 98% alkyl acrylate containing 4 to 12 carbon atoms; N-vinylpyrrolidone from about 0.1% to 0.5%; About 0.5% to 4.5% of carboxylic acid unsaturated in ethylene form; And 0% to about 0.5% (more preferably about 0.1% to 0.5%) of a multifunctional crosslinking monomer, wherein the total amount of the monomer is 100% by weight. The emulsified product is pourable because it has a viscosity of 300 cps to 15,000 cps with at least a bimodal particle-size distribution and a solids content of at least 68 wt%. In some embodiments, methyl acrylate or ethyl acrylate may be contained in small amounts, for example up to about 6% by weight, based on the total amount of monomers. Small amounts of other monomers commonly used in the production of PSA polymers may be used.

The emulsion polymer according to the invention is prepared in a direct manner. In one embodiment, the emulsified product is (a) a pre-emulsified first portion of a plurality of monomers fed to the reactor in two distinct feedstocks, and (b) a second portion of the plurality of monomers. Formed sequentially by polymerizing the first feedstock of the two feedstocks relatively slowly, containing about 0.4 to 1% by weight of the first emulsified portion of the plurality of monomers, and the second feedstock relative And from about 99 to 99.6% by weight of the first part pre-emulsified of the plurality of monomers. The second portion of the plurality of monomers, although not essential, can be pre-emulsified before being fed to the reactor and polymerized.

In another embodiment, the emulsified product is formed by polymerizing one pre-emulsion of a plurality of monomers fed to the reactor with two distinct feedstocks, wherein the first feedstock of the two feedstocks is fed relatively slowly. And the second feedstock is supplied relatively quickly, and the first feedstock and the second feedstock preferably contain the amounts of the relative weight percentages described above.

Preferably, the surfactant system consists of three kinds of anionic surfactants, each having a specific main function, namely particle generation function, emulsion stabilization function and wet-out / coating enhancement function.

According to a preferred embodiment of the present invention, an emulsion having a high solids content and a low viscosity is provided, wherein the emulsion comprises an emulsified product copolymerized with a plurality of monomers in the presence of a plurality of surfactants, wherein the plurality of monomers, About 90% to 98% of an alkyl acrylate (a) having an alkyl group containing 4 to 12 carbon atoms in weight percent based on the total amount of the monomers; N-vinylpyrrolidone from about 0.1% to 0.5%; About 0.5% to 4.5% of carboxylic acid unsaturated in ethylene form; And 0% to about 0.5% (more preferably about 0.1% to 0.5%) of the multifunctional crosslinking monomer. Optionally, said plurality of monomers contains up to about 6% by weight methyl acrylate or ethyl acrylate. The emulsified polymerization product has at least a bimodal particle size distribution, more preferably a multimodal particle size distribution.

Non-limiting examples of alkyl acrylates having 4 to 12 carbon atoms in the alkyl group include butyl, pentyl, hexyl, heptyl, octyl, isooctyl, ethylhexyl, nonyl, decyl, and dodecyl acrylate. Preferred among 2-ethylhexyl acrylate, butyl acrylate and isooctyl acrylate (three commercially available acrylates commonly used in the preparation of PSA acrylic polymers) is 2-ethylhexyl acrylate, which is 2-ethylhexyl acrylate. This is because a copolymer based on has a lower T _g than a copolymer based on butyl acrylate. Isooctyl acrylate is less preferred because emulsion polymers based thereon appear to be less stable than polymers based on 2-ethylhexyl acrylate.

Non-limiting examples of carboxylic acids unsaturated in ethylene form include acrylic acid, methacrylic acid, beta-carboxyethyl acrylate and itanoic acid. Mixtures of acrylic acid and methacrylic acid are preferred.

As used herein, the term "multifunctional crosslinking monomer" refers to a monomer copolymerizable with an acrylic monomer, in which at least one carbon-carbon double bond and at least one other functional group can cause a polymerization reaction or a crosslinking reaction. Means. Non-limiting examples of such monomers include multifunctional (meth) acrylates such as diacrylate, triacrylate, dimethyl acrylate and trimethyl acrylate; Multifunctional allyl compounds such as diallyl maleate and allyl methacrylate; Polyfunctional crosslinking monomers having vinyl groups; And multifunctional crosslinking monomers having reactive heteroatom containing functional groups such as imidazolidone groups. The non-limiting list includes the following monomers.

Multifunctional monomer Abbreviation

Allyl Methacrylate AMA

Diallyl maleateDAM

DivinylbenzeneDVB

Ethylene Glycol Dimethacrylate EGDMA

N, N'-methylene-bis-acrylamideNNMBA

Tripropylene Glycol Diacrylate TPGDA

Triallyl cyanurate TAC

Tetraethylene Glycol DiacrylateTEGDA

Triethylene glycol dimethacrylate TEDMA, TEGMA

Trimethylolpropane triacrylate TMPTA

Trimethylolpropane trimethacrylateTMPTMA, TRIM

Trimethylolpropane diallyl ether TMPDAE

Imidazolidone methacrylate MEIO

A preferred multifunctional crosslinking monomer is Norsocryl7 104 (manufactured by Elf Atochem), a 35-37% by weight solution of ethyl imidazolidone methacrylate (MEIO) dissolved in methyl methacrylate. Both MEIO and methyl methacrylate are copolymerized with other monomers present in the monomer mixture; Methyl methacrylate is therefore considered to be one of the "plural monomers" in the examples containing Norsocryl7 104. In contrast, MEIO is dissolved in different solvents, preferably reactive (copolymerizable) diluents, for example short chain alkyl (meth) acrylates such as methyl, ethyl or propyl (meth) acrylates.

Multifunctional crosslinking monomers improve the shear performance (enhanced adhesive strength) of the resulting emulsion polymer. However, when too many crosslinking monomers are used, the adhesion performance (eg looptack) is substantially reduced. It is particularly advantageous to include multifunctional crosslinking monomers in low temperature PSA formulations. By doing so good shear strength can be obtained at low temperatures without loss of viscosity.

Optionally, the plurality of monomers comprises a small amount of methyl acrylate and / or ethyl acrylate, for example, in an amount of from 0 to about 6 weight percent, more preferably from about 0.2 to 0.5 weight percent, based on the total amount of monomers. Include. Inclusion of methyl acrylate or ethyl acrylate appears to accelerate the overall polymerization rate and reduce the amount of residual monomer (unreacted monomer remaining after the polymerization reaction is complete). In some embodiments, the plurality of monomers also includes small amounts of one or more types of polymerizable monomers conventionally used to prepare PSA polymers. Non-limiting examples include diesters of carboxylic acids unsaturated in the form of vinyl acetate, styrene and ethylene such as dioctyl maleate, dioctyl fumarate and the like. When other monomers are included, such monomers are each present at about 15% by weight or less, based on the total amount of monomers, and correspondingly the amount of alkyl acrylate is reduced. When the resulting polymer is to be used as PSA, the weight percentage of any additional monomer is further inhibited by the desired T _g in the resulting polymer, at which time T _g is generally at least 25 above the lowest expected use temperature of the adhesive. Should be low.

Small amounts of N-vinyl pyrrolidone (NVP) in the monomer mixture are not critical to obtaining pressure-sensitive adhesive properties, but appear to form more stable emulsion polymers and may contribute to lowering the viscosity. Good results are obtained when the amount of NVP present is about 0.1-0.5%, more preferably about 0.2-0.3%. If it exceeds 0.5%, the particle size distribution and viscosity may deteriorate.

It is preferable to use several surfactant in the process of superposing | polymerizing a monomer, and an anionic surfactant is the most preferable among these. In particular, a mixture of three different surfactants, each with a primary function, gives very good results. The first surfactant has a primary function of producing emulsion polymer particles and is present in an amount of about 10-20% by weight based on the total weight of the surfactant. The second surfactant has a main function of stabilizing the emulsion and is present in an amount of about 20-30% by weight. The third surfactant has a main function of enhancing the wettability and / or emulsion coating properties of the substrate and is present in an amount of about 20-30% by weight. The sum of all surfactants is of course 100%.

Surfactants of the first form are preferably sulfates of ethoxylated alcohols, for example sodium lauryl ether sulfate. A non-limiting example is Disponil FES 77 from Henkel Corp.

The second type of surfactant is preferably sulfosuccinate or a derivative thereof, for example sodium ethoxylated alcohol half ester of sulfosuccinic acid. Non-limiting examples include Cytec Industries, Inc. Aerosol A-102.

The third type of surfactant is preferably sulfosuccinate or a derivative thereof, for example, dioctyl ester of sodium sulfosuccinic acid. A non-limiting example is Aerosol OT-75, also available from Cytec Industries, Inc.

In addition to the monomers and surfactants described above, additional components, reactants, process aids, and other components are used to implement preferred embodiments of the present invention. Non-limiting examples include polymerization catalysts (initiators) such as potassium persulfate (K ₂ S ₂ O ₈ ); Electrolytes such as tetrasodium pyrophosphate (the electrolyte used to control TSPP--emulsion stability and particle size) and other sodium or potassium salts; chain transfer agents such as n-dodecyl mercaptan (n-DDM); Basic solutions (eg ammonia water, sodium hydroxide, etc.); Accelerators such as sodium formaldehyde sulfoxylate (AWC—used to decompose excess initiator); Antifoaming agents such as Drewplus L-191; Biocide such as Kathon LX; And emulsion media (continuous phase) such as water or mixtures of water and lower alcohols.

The emulsion polymer according to the invention is prepared in a direct manner. In one embodiment, the first portion of the pre-emulsified monomer is fed to the reactor to polymerize into two distinct feedstocks, followed by a second portion of the monomer regardless of whether it is pre-emulsified. As such, in one embodiment, a portion of the monomers is dispersed in an aqueous medium with one or more types of surfactant and the resulting preemulsion is fed to the reactor, initially with a very small initial amount of the preemulsion, for example about 2 Beginning with a slow supply of the first portion of the pre-emulsified plurality of monomers of up to about, preferably more than about 0.4-1% by weight, followed by about 99-99.6% by weight of the first portion of the pre-emulsified plurality of monomers The second feedstock containing the feed quickly. After opening, a second portion of the monomer is fed to the reactor. It has been found that ideal results (high solids content and low viscosity) are obtained when the second feed rate is at least about 5 times faster than the first feed rate. According to an embodiment, the second feed rate reaches 10 or even 20 times the first feed rate.

In another embodiment, all of the plurality of monomers are pre-emulsified and then fed to the reactor as a split feedstock. That is, the first feedstock contains a very small amount, for example about 2% by weight or less, more preferably about 0.4 to 1% by weight of a pre-emulsion of monomers, and the second feedstock contains the remaining monomers, for example about It contains 99-99.6% by weight preliminary emulsion. As described above, the relative feed rate is also greatly different such that the second feed rate is at least about five times as large as the first feed rate.

Polymerization, when a small amount of monomer is fed slowly, produces a small amount of very small (<300 nm) particle size polymer, as evidenced by the slightly blue (white) tint of the reaction mixture. It is believed. The subsequent higher speed and higher concentration of monomer supply is believed to produce larger (300-700 nm or> 700 nm) polymer particles.

Emulsion polymers prepared according to the present invention generally have a high molecular weight (> 1,000,000), high gel content (> 60% or 70% by weight), high solids content and low viscosity, and, in the case of PSA polymers, the expected service temperature of PSA At least about 25 ° C. lower glass transition temperature (T _g ). For example, emulsion polymers for PSA used in room temperature applications have a T _g of less than about 0 ° C. For low temperature applications it is preferred that the polymer has a T _g of less than about −50 ° C.

When the solid content is measured immediately after the polymerization reaction, a high value of 75 to 78 wt% appears. (In at least one embodiment, a solids content of about 82 weight percent is obtained.) After neutralizing and diluted with deionized water, the emulsified product has a solids content of at least about 70 weight percent (at least 68 to 69 weight percent). Despite the high solids content, the emulsified product of the polymerization reaction is an injectable material that has a viscosity of about 300-15,000 cps, not pasty. The viscosity of certain polymers according to the present invention can be controlled by the selection of monomers and surfactants and their amount and the control of the monomer feed rate. It is also possible to dilute high viscosity emulsions of high solids content to lower viscosities if necessary.

The desired specific solids content and viscosity for a given emulsion polymer depends in part on the manner in which the emulsion polymer is coated or otherwise applied to the backing substrate or other substrate. For example, when high viscosity materials are used, the reverse gravure and nip-fed coaters used to make PSA structures will not work properly, so the approximate limit of acceptable viscosity is 1,000 cps. It is known. However, to date such low viscosity materials have not been obtained at high solids content. As another example, especially when the material to be coated is thixotropic, die-coating techniques can handle materials with much higher viscosities up to 10,000 cps or more. Under high shear forces occurring at the lip site of the extrusion die coater, the viscosity of the shear-thinning emulsion polymer will be much lower than 10,000 cps.

When coated and dried on a substrate, the polymer of the present invention is inherently tacky and therefore useful for preparing adhesives, labels, and other structures, including paints, primers, coatings, barrier layers, pressure sensitive adhesive tapes. In one embodiment, the coating structure is coated by coating the polymer emulsion on a release liner, drying the emulsion, and then laminating the resulting subassembly on a facestock or other substrate such as, for example, paper or film backing. Is manufactured. Alternatively, the emulsion can be coated directly onto the fabric, dried and protected until use by a release liner or a structure backsize with low release energy. In another embodiment, a coating structure is prepared by simply coating the emulsion polymer on a substrate and leaving it to dry.

The following examples illustrate, without limitation, various examples of the invention.

Example 1

Using the components listed in Table 1A, an emulsion polymer having a high solids content and a low viscosity was prepared as follows:

Except for the kick-off catalyst, initial reactor charge A was charged to the polymerization reactor and heated to 76 ° C. Stirring speed was set to 120 rpm (laboratory) or 50 rpm (pilot reactor). Monomer mixtures (1) and (2) and pre-emulsion soap (surfactant) solutions were prepared separately. The monomer mixture (1) was added to the soap solution with stirring to form a stable monomer preemulsion (1) and stored for delay addition. Catalyst solution was prepared and stored for delayed addition. When the reactor reached 76 ° C., the starting catalyst was added and the reactor was purged with nitrogen (N ₂ ) for 5 minutes. The nitrogen supply was then stopped. Preliminary emulsion (1) feed was started at a rate of 1.00 g / min over 3.8 minutes, followed by a second rapid feed at 4.85 g / min. 20 minutes after the start of the preliminary emulsion feed, the catalyst feed was started at a rate of 0.20 parts by weight over 207 minutes. The batch temperature was maintained in the range of 78 ° C. to 86 ° C. The stirring speed was increased as necessary to ensure effective mixing. 10 minutes after the addition of the pre-emulsion 1 to the reactor, the monomer mixture 2 was fed to the reactor at a rate of 1.55 g / min over 55 minutes. Ten minutes after 90% of the catalyst retardant had been charged, the remaining amount of catalyst was fed at a rate of 1.00 parts by weight, and the batch was then held in the range of 78 ° C. to 86 ° C. for an additional 30 minutes. Residual monomer concentration was measured, and when the residual monomer concentration was less than 0.10%, cooling for the batch was started up to 35 ° C. After the temperature had dropped to 60 ° C., a primary 19% ammonia solution and a 50% AWC solution were added. A secondary 19% ammonia solution and deionized water were added to adjust the pH and solids / viscosity of the emulsified product, which was then filtered through a 20-50 μm filter. Residual monomer, pH, total solids content and viscosity in the obtained product were measured. Table 1B shows the parts by weight and time in minutes for the reaction retardant. Theoretical solid content was 67.62%.

Table 1A-Example 1

ingredient Mass (g)

Reactor input

Deionized Water

FES 77 (32.50%) 0.15

K ₂ S ₂ O ₈ (Akick-ff @ catalyst) 1.50

110.00

Pre-emulsion soap solution

Deionized Water 86.00

TSPP (59.70%) 2.60

OT-75 (75.00%) 2.20

A-102 (31.50%) 7.70

FES-77 (32.50%) 18.30

116.80

Monomer mixture (1) (2)

2-EHA525.50 81.30

MA 2.70 1.30

NVP 2.80 0.00

MAA 7.10 1.80

AA 2.90 0.00

Norsocryl 104 2.50 0.50

n-DDM 0.30 0.10

543.80 85.00

Catalyst solution to delay

Deionized Water 44.30

K ₂ S ₂ O ₈ 1.70

46.00

Etc

Primary NH ₃ solution (19%) 3.50

50% AWC solution 0.30

Drewplus L-191 0.30

Kathon LX (1.50%) 0.30

Second NH ₃ solution (19%) 1.00

Deionized Water 13.00

Total

Solids content: 69.9 0.5%

Table 1B-Delayed Addition

ingredient Volume (g) Minutes Speed (g / min)

Preparative Emulsion (1)

Initial 3.80 3.80 1.00

Rest 656.80 135.00 4.85

catalyst

Initial 41.40 207.00 0.20

Remaining 4.60 4.60 1.00

Monomer (2) 85.00 55.00 1.55

The emulsion polymer of Example 1 may have a pH of 6.8 to 7.5; Measured grit of less than 80 ppm on a 55 μm filter; Less than 0.10% residual monomer; And Brookfield LVT viscometer (# 3 spindle) with a viscosity of 1,000 to 5,000 cps as measured at 30 rpm, 25 ° C. This very low grit level is a further advantage of the present invention. On the other hand, many commercial polymerization reactions result in grit greater than 1,000 ppm. When coated, such high grit compositions are likely to have streaks and wrinkled appearance.

Example 2

An emulsion polymer having a high solids content and a low viscosity is prepared according to the method of Example 1, wherein a single monomer mixture ((1) + (2)) is used to prepare a preliminary emulsion, and the preemulsion is then divided feedstock And the first feedstock contains about 0.60% by weight of the monomer pre-emulsion and is fed at a rate of about 1.00 g / min, and the second feedstock contains about 99.4% by weight of the monomer pre-emulsion It is fed at a rate of about 4.85 g / min.

Many PSA structures were prepared and tested for adhesion performance on low density polyethylene (LDPE) and corrugated cardboard. The emulsion polymer prepared according to the invention was coated onto a siliconized release liner, dried for 10 minutes at 75 ° C. in an oven and laminated to 60 lbs / ream of high gloss paper fabric. The weight of the adhesive coat measured after drying was 20 ± 1 g / m 2. The PSA structures were tested and compared to commercial products Flexcryl ATA, a product of the Department of Polymer Chemistry from Air Products and Chemical, Inc .. The structure was tested for 90 ° peel, roof tack, T-peel and shear strength. A “cold box” test, ie a looptack test conducted in an environmental chamber at three temperatures (-5 ° C., −20 ° C., −35 ° C.), was performed on an HDPE substrate. The T-peel test is a self-adhesive test designed to indicate performance in aircraft luggage tag applications.

Despite the fact that the test results are somewhat variable at low temperatures (presumably due to condensation on the substrate), PSAs prepared using the emulsion polymers described in the present invention exhibit adhesion performance comparable to commercially available Flexcryl products. What is shown is certain. Some tests showed better performance at certain temperatures.

Although the present invention has been described through the above-described exemplary embodiments, the present invention is not limited thereto. Those skilled in the art will appreciate that other modifications may be made to the emulsions, methods and PSA structures according to the invention without departing from the scope of the invention. For example, tackifiers and / or plasticizers can be added to control PSA performance and utility. Tackifiers have the property of increasing the glass transition temperature and lowering the modulus of the polymer to which it is added. By adding a tackifier, the temperature range in which the emulsion polymer can be used can be widened. In addition, many tackifying resins have a solid content of 50 to 60 wt%. The addition of such tackifiers to polymers with high solids content lowers the overall solids content of the composition. For example, 40 parts by weight of a tackifier having a solid content of 55% is added to 60 parts by weight of an emulsion having a solid content of 65% to obtain a final product having a total solid content of 61% by weight. Starting with an emulsion polymer of 75% solids content, the resulting composition will have 67% solids by weight. Thus, the addition of a tackifier with a high solids content and a low viscosity polymer having a T _g higher than the desired temperature as a starting material (thus lowering the T _g throughout the composition) results in the desired solids content, viscosity and A tackifying composition having a T _g can be obtained.

The process of emulsion polymerization according to the invention has general utility which extends beyond the scope of the specific monomer systems described herein. Slowly feeding the monomer initially (about 0.4 to 1% by weight of monomer) and then rapidly feeding the secondary monomer (about 99 to 99.6% by weight of monomer) yields a multimodal or at least bimodal particle size distribution.

Preferably, but not necessarily, it is contemplated that plural middle class surfactants may be used to polymerize acrylic monomers and other monomers in the emulsion according to the process of the present invention.

The term "about" as used in connection with the range of numerical values throughout this specification and claims is intended to modify both the upper and lower of the stated values.

Claims (39)

As an emulsion with high solids content and low viscosity, An emulsified product copolymerized with a plurality of monomers in the presence of a plurality of surfactants, The plurality of monomers comprises about 90 to 98% of an alkyl acrylate containing 4 to 12 carbon atoms in weight percent based on the total amount of the monomers; About 0.1 to 0.5% of N-vinylpyrrolidone; About 0.5 to 4.5% of carboxylic acids unsaturated in ethylene form; And 0% to about 0.5% multifunctional crosslinking monomer, The emulsified product has at least a bimodal particle size distribution, a solids content of at least 68% by weight, and a viscosity of 300-15,000 cps. emulsion. The method of claim 1, Emulsion, characterized in that the emulsion product has a multimodal particle size distribution. The method of claim 1, Wherein said plurality of monomers further comprises methyl acrylate and / or ethyl acrylate in an amount of about 6% by weight or less based on the total weight of said monomers. The method of claim 1, The alkyl acrylate is selected from the group consisting of ethylhexyl acrylate, butyl acrylate, and mixtures thereof. The method of claim 1, Emulsion, characterized in that the alkyl acrylate comprises ethylhexyl acrylate. The method of claim 1, The carboxylic acid unsaturated in the ethylene form is selected from the group consisting of acrylic acid, methacrylic acid, beta-carboxyethyl acrylate, itaconic acid, and mixtures thereof. The method of claim 1, The carboxylic acid unsaturated in the ethylene form comprises a mixture of acrylic acid and methacrylic acid. The method of claim 1, Wherein said multifunctional crosslinking monomer is selected from the group consisting of a polyfunctional (meth) acrylate, a polyfunctional allyl compound, a polyfunctional crosslinking monomer having a vinyl group, and a multifunctional crosslinking monomer having a reactive heteroatom-containing functional group. Emulsion. The method of claim 1, Emulsion, characterized in that the multifunctional crosslinking monomer comprises ethyl imidazolidone methacrylate. The method of claim 9, The ethyl imidazolidone methacrylate is dissolved in a solvent. The method of claim 10, Emulsion, characterized in that the solvent comprises a reactive diluent. The method of claim 11, Emulsion, characterized in that the reactive diluent comprises a short chain alkyl (meth) acrylate. The method of claim 1, The plurality of monomers are about 90-98 wt% ethylhexyl acrylate, about 0.1-0.5 wt% N-vinyl pyrrolidone, about 0.5-4.5 wt% mixture of acrylic acid and methacrylic acid, methyl methacryl Emulsion comprising from about 0.1 to 0.5% by weight of ethyl imidazolidone methacrylate, and up to about 6% by weight of methyl acrylate and / or ethyl acrylate dissolved in rate. The method of claim 1, And said plurality of monomers further comprises at least one of diesters of carboxylic acids unsaturated in the form of vinyl acetate, styrene, and ethylene. The method of claim 1, The emulsified product is (a) a pre-emulsified first portion of a plurality of monomers fed to the reactor in two distinct feeds, and (b) a second portion of the plurality of monomers. Formed by polymerization of The first feedstock of the two distinct feedstocks is fed relatively slowly and contains about 0.4 to 1% by weight of the pre-emulsified first portion of the plurality of monomers, the second feedstock is supplied relatively quickly and the Contains from about 99 to 99.6% by weight of the first emulsified portion of the plurality of monomers Emulsion, characterized in that. The method of claim 1, The emulsified product is formed by polymerization as a pre-emulsion of a plurality of monomers is fed to the reactor in two distinct feedstocks, The first feedstock of the two distinct feedstocks is supplied relatively slowly and contains about 0.4 to 1% by weight of the plurality of monomers, the second feedstock is supplied relatively quickly and the 99 to Containing 99.6% by weight Emulsion, characterized in that. The method of claim 1, The plurality of surfactants are weight percent based on the total weight of the surfactant, 10 to 20% of the first surfactant mainly having particles, and 20-30% of the second surfactant mainly having emulsion stabilization. And 55% to 65% of a third surfactant having a main function of imparting wet out and / or emulsion coatability of the substrate. The method of claim 17, Emulsion, characterized in that the first surfactant comprises ethoxylated lauryl alcohol, long chain fatty acid. The method of claim 17, Emulsion, characterized in that the second surfactant comprises a half ester of succinic acid. The method of claim 17, The third surfactant comprises an succinic sulfonic acid. The method of claim 1, Wherein said plurality of surfactants comprise ethoxylated lauryl alcohol, long chain fatty acids, half esters of succinic acid, and succinic sulfonic acid. As an emulsion with high solids content and low viscosity, An emulsified product copolymerized with a plurality of monomers in the presence of a plurality of surfactants, The plurality of monomers comprises about 90 to 98% of an alkyl acrylate containing 4 to 12 carbon atoms in weight percent based on the total amount of the monomers; About 0.1 to 0.5% of N-vinylpyrrolidone; About 0.5 to 4.5% of carboxylic acids unsaturated in ethylene form; And 0% to about 0.5% multifunctional crosslinking monomer, The emulsification product is in turn by polymerizing (a) a pre-emulsified first portion of the plurality of monomers fed to the reactor in two distinct feedstocks, and (b) a second portion of the plurality of monomers. Formed, The first feedstock of the two distinct feedstocks contains about 0.4 to 1% by weight of the pre-emulsified first portion of the plurality of monomers and is metered to the reactor at a relatively slow first feed rate, and a second feed The feedstock contains about 99-99.6% by weight of the pre-emulsified first portion of the plurality of monomers and is metered into the reactor at a relatively fast second feed rate. emulsion. The method of claim 22, And said second feed rate is at least five times faster than said first feed rate. (a) applying the high solids content and low viscosity emulsion of claim 1 onto a substrate, and (b) drying the emulsion Coated construction formed by. The method of claim 24, And the emulsion is applied onto the substrate, dried and then protected with a release liner. The method of claim 24, Wherein the emulsion is applied and dried on a release liner to form a subassembly, which is then laminated onto a substrate. The method of claim 24, Coated structure, characterized in that the substrate is paper or film. The method of claim 27, Coated structure, characterized in that the substrate is die-cut. The method of claim 24, Coated structure, characterized in that the structure is a PSA tape or label. A process for preparing an emulsion polymer having a high solids content and a low viscosity, Copolymerizing the plurality of monomers in the presence of the plurality of surfactants, The plurality of copolymers comprise about 90 to 98% of an alkyl acrylate containing 4 to 12 carbon atoms in weight percent based on the total amount of the monomers; About 0.1 to 0.5% of N-vinylpyrrolidone; About 0.5 to 4.5% of carboxylic acids unsaturated in ethylene form; And 0% to about 0.5% multifunctional crosslinking monomer, (a) the pre-emulsified first portion of the plurality of monomers is fed to the reactor as two distinct feedstocks to carry out the polymerization reaction, and (b) the second portion of the plurality of monomers is fed to the reactor, Continues, The first feedstock of the two distinct feedstocks contains about 0.4-1% by weight of the first portion of the plurality of monomers and is metered into the reactor at a relatively slow first feed rate, and the second feedstock is A first portion of the plurality of monomers containing about 99-99.6% by weight and metered into the reactor at a relatively fast second feed rate Emulsion Polymer Preparation Method. The method of claim 30, And wherein said second feed rate is at least five times faster than said first feed rate. A process for preparing an emulsion polymer having a high solids content and a low viscosity, Copolymerizing the plurality of monomers in the presence of the plurality of surfactants, The plurality of copolymers comprise about 90 to 98% of an alkyl acrylate containing 4 to 12 carbon atoms in weight percent based on the total amount of the monomers; About 0.1 to 0.5% of N-vinylpyrrolidone; About 0.5 to 4.5% of carboxylic acids unsaturated in ethylene form; And 0% to about 0.5% multifunctional crosslinking monomer, The polymerization reaction occurs as the pre-emulsion of the plurality of monomers is fed to the reactor in two distinct feedstocks, The first feedstock of the two distinct feedstocks contains about 0.4-1% by weight of the plurality of monomers and is metered to the reactor at a relatively slow first feed rate, and the second feedstock contains the plurality of monomers. Containing from about 99 to 99.6% by weight and metered to the reactor at a relatively fast second feed rate Emulsion Polymer Preparation Method. As an emulsion with high solids content and low viscosity, An emulsified product copolymerized with a plurality of monomers in the presence of a plurality of surfactants, The plurality of monomers are weight percent based on the total amount of the monomers, about 96.5% ethylhexyl acrylate, about 0.6% methyl acrylate, about 0.5% N-vinyl pyrrolidone, and about methacrylic acid 1.4%, about 0.5% acrylic acid, about 0.18% imidazolidone methacrylate, and about 0.32% methyl methacrylate, The emulsified product has at least a bimodal particle size distribution. emulsion. The method of claim 33, wherein Emulsion, characterized in that the emulsified product has a multimodal particle size distribution. The method of claim 33, wherein The emulsified product is formed in turn by polymerizing (a) a first part pre-emulsified of a plurality of monomers fed to the reactor with two distinct feedstocks, and (b) a second part of the plurality of monomers, The first feedstock of the two distinct feedstocks is fed relatively slowly and contains about 0.4 to 1% by weight of the pre-emulsified first portion of the plurality of monomers, the second feedstock is supplied relatively quickly and the Contains from about 99 to 99.6% by weight of the first emulsified portion of the plurality of monomers Emulsion, characterized in that. The method of claim 33, wherein The emulsified product is formed by polymerization as a pre-emulsion of a plurality of monomers is fed to the reactor in two distinct feedstocks, The first feedstock of the two distinct feedstocks is supplied relatively slowly and contains about 0.4 to 1% by weight of the plurality of monomers, the second feedstock is supplied relatively quickly and the 99 to Containing 99.6% by weight Emulsion, characterized in that. The method of claim 1 or 22, Emulsion comprising a tackifier or a plasticizer, or a tackifier and a plasticizer. The method of claim 22, Emulsion comprising a tackifier or a plasticizer, or a tackifier and a plasticizer. (a) applying the high solids content and low viscosity emulsion of claim 22 onto a substrate, and (b) drying the emulsion Coated structures formed by.