阅读说明：本技术 丙烯酸类压敏粘合剂 (Acrylic pressure sensitive adhesive ) 是由 黎淳昭 陈梁 S·卡雷丁 D·马特兰 G·斯特恩贝克 盛鑫鑫 张心亚 于 2019-03-04 设计创作，主要内容包括：本发明涉及丙烯酸类压敏粘合剂。丙烯酸类聚合物可包括：5重量％至90重量％的(甲基)丙烯酸烷基酯单体的混合物,其中该混合物包含根据CH<Sub>2</Sub>═C(R<Sup>2</Sup>)-(CO)-OR<Sup>1</Sup>的第一(甲基)丙烯酸烷基酯单体,其中R<Sup>1</Sup>是具有碳数为6-13和支化指数为2-4的烷基并且R<Sup>2</Sup>是氢或甲基；和选自以下的一种或多种单体：0重量％至80重量％的根据CH<Sub>2</Sub>═C(R<Sup>4</Sup>)-(CO)-OR<Sup>3</Sup>的第二(甲基)丙烯酸烷基酯,其中R<Sup>3</Sup>是具有碳数为1-14和支化指数为0-1的烷基并且R<Sup>4</Sup>是氢或甲基；0重量％至10重量％的羟基丙烯酸类单体；和0重量％至10重量％的含有羧酸的单体。(The present invention relates to acrylic pressure sensitive adhesives. The acrylic polymer may include: 5 to 90 wt.% of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a monomer according to CH 2 ═C(R 2 )‑(CO)‑OR 1 A first alkyl (meth) acrylate monomer of (1), wherein R 1 Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 andR 2 is hydrogen or methyl; and one or more monomers selected from the group consisting of: 0% to 80% by weight of a base according to CH 2 ═C(R 4 )‑(CO)‑OR 3 A second alkyl (meth) acrylate of (2), wherein R 3 Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R 4 Is hydrogen or methyl; 0 to 10% by weight of a hydroxy acrylic monomer; and 0 to 10% by weight of a carboxylic acid containing monomer.)

1. An acrylic polymer comprising:

5 to 90 wt.% of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a monomer according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and

one or more monomers selected from the group consisting of:

0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl;

0 to 10% by weight of a hydroxy acrylic monomer; and

0 to 10% by weight of a carboxylic acid containing monomer.

2. The acrylic polymer of claim 1 further comprising: 0.1 to 10% by weight of a vinyl monomer selected from: (meth) acrylonitrile, (meth) acrylamide, vinyl acetate, vinylidene chloride, styrene, and methylstyrene.

3. The acrylic polymer of any of the preceding claims wherein the mixture of alkyl (meth) acrylate monomers is present at 20 wt% to 60 wt%.

4. The acrylic polymer of any of the preceding claims wherein the second alkyl (meth) acrylate is present at 10 wt% to 50 wt%.

5. The acrylic polymer of any of the preceding claims wherein the hydroxyacrylic monomer is present at 0.3 wt% to 8 wt%.

6. The acrylic polymer of any of the preceding claims wherein the carboxylic acid containing monomer is present at 0.2 wt% to 8 wt%.

7. The acrylic polymer of any of the preceding claims wherein 90 weight percent of the mixture of alkyl (meth) acrylate monomers has a carbon number range selected from the group consisting of: c_6-8、C_6-9、C_6-10、C_6-11、C_7-9、C_7-10、C_7-11、C_7-12、C_7-13、C_8-10、C_8-11、C_8-12、C_9-11、C_9-12、C_9-13、C_10-12、C_10-13、C_10-14、C_11-13、C_11-14And C_11-15。

8. The acrylic polymer of any of the preceding claims wherein the mixture of alkyl (meth) acrylate monomers has a branching index of from 1.25 to 4.

9. The acrylic polymer of any of the preceding claims wherein the mixture of alkyl (meth) acrylate monomers further comprises at least one alkyl (meth) acrylate monomer according to CH different from the first alkyl (meth) acrylate monomer₂═C(R²)-(CO)-OR¹The (meth) acrylic acid alkyl ester monomer of (1).

10. The acrylic polymer of claim 9 wherein the first alkyl (meth) acrylate monomer and the at least one alkyl (meth) acrylate monomer, in total, comprise from 15 weight percent to 100 weight percent of the mixture of alkyl (meth) acrylate monomers.

11. The acrylic polymer of claim 9, wherein the first alkyl (meth) acrylate monomer and the at least one alkyl (meth) acrylate monomer, in total, comprise 30 to 90 weight percent of the mixture of alkyl (meth) acrylate monomers.

12. A pressure sensitive adhesive comprising:

an acrylic polymer emulsion polymerized in water, the acrylic polymer comprising:

5 to 90 wt.% of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a monomer according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and

one or more monomers selected from the group consisting of:

0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl;

0 to 10% by weight of a hydroxy acrylic monomer; and

0 to 10% by weight of a carboxylic acid containing monomer.

13. The pressure sensitive adhesive of claim 12, wherein the acrylic polymer emulsified in water has a viscosity at 25 ℃ and 40 weight percent solids of 200 centipoise (cP) to 400 cP.

14. The pressure sensitive adhesive of one of claims 12-13 wherein the acrylic polymer has a gel content of about 50% to about 75%.

15. The pressure sensitive adhesive of one of claims 12-14, further comprising: 0.1 to 10% by weight of a vinyl monomer selected from: (meth) acrylonitrile, (meth) acrylamide, vinyl acetate, vinylidene chloride, styrene, and methylstyrene.

16. The pressure sensitive adhesive of one of claims 12-15 wherein the mixture of alkyl (meth) acrylate monomers has a branching index of 1.25 to 4.

17. The pressure sensitive adhesive of one of claims 12-16 wherein the mixture of alkyl (meth) acrylate monomers further comprises at least one monomer according to CH that is different from the first alkyl (meth) acrylate monomer₂═C(R²)-(CO)-OR¹The (meth) acrylic acid alkyl ester monomer of (1).

18. The pressure sensitive adhesive of claim 17 wherein the first alkyl (meth) acrylate monomer and the at least one alkyl (meth) acrylate monomer, in total, comprise 30 to 90 weight percent of the mixture of alkyl (meth) acrylate monomers.

19. A composition comprising:

a substrate having thereon an acrylic pressure sensitive adhesive, wherein the acrylic pressure sensitive adhesive is the acrylic pressure sensitive adhesive of one of claims 12-18.

20. The method comprises the following steps:

emulsion polymerizing a mixture of monomers in the presence of an initiator, the mixture of monomers comprising:

5 to 90% by weight of a mixture of alkyl (meth) acrylate monomers, wherein the mixing is carried outThe substance comprises according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and

one or more monomers selected from the group consisting of:

0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl;

0 to 10% by weight of a hydroxy acrylic monomer; and

0 to 10% by weight of a carboxylic acid containing monomer.

Technical Field

The present disclosure relates to acrylic pressure sensitive adhesives.

Background

Acrylic polymer compositions have long been used as adhesive compositions, particularly in pressure sensitive adhesive ("PSA") compositions. They exhibit adhesion to a wide variety of surfaces, exhibit good low temperature properties, generally produce attractive clear adhesives and possess excellent heat, aging and UV stability. Acrylic adhesive polymers are available as organic (solvent) solutions, aqueous emulsions, and as melt-applied 100% solids thermoplastic systems. Initially, the most common PSA was solvent acrylic, but market demand has led to a rapid growth in water-based acrylic, also known as emulsion acrylic, adhesives.

Traditionally, acrylic PSA compositions have been property adjusted by selection of acrylic monomers and polymerization conditions. Examples of such properties are cohesion (e.g. shear strength) and adhesion (e.g. adhesion and peel strength). For example, acrylate monomers that lower the glass transition temperature of acrylic polymers (such as butyl acrylate and 2-ethylhexyl acrylate) improve adhesion properties, while acrylate monomers and vinyl monomers that raise the glass transition temperature of acrylic polymers (such as methyl methacrylate, styrene, and vinyl acetate) improve cohesion properties. Unfortunately, using more of one type of monomer results in less of the other, so cohesion and adhesion are often inversely related, such that an improvement in one property causes a decline in the other.

Disclosure of Invention

The present disclosure relates to emulsion acrylic PSAs having improved cohesion with maintained high adhesion. More specifically, the emulsion acrylic PSAs described herein utilize (meth) acrylate monomers derived from primary alcohols having carbon chains of varying carbon numbers and varying branching numbers. Such monomers are referred to herein as alkyl (meth) acrylate monomers.

A first non-limiting example of the present disclosure is an acrylic polymer comprising: 5 to 90 wt.% of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a monomer according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and one or more monomers selected from the group consisting of: 0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl; 0 to 10% by weight of a hydroxy acrylic monomer; and 0 to 10% by weight of a carboxylic acid containing monomer.

A second non-limiting example of the present disclosure is a pressure sensitive adhesive comprising: an acrylic polymer emulsion polymerized in water, the acrylic polymer comprising: 5 to 90 wt.% of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a monomer according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and one or more monomers selected from the group consisting of: 0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl; 0 to 10% by weight of a hydroxy acrylic monomer; and 0 to 10% by weight of a carboxylic acid containing monomer. The pressure sensitive adhesive may optionally be further characterized by: (A) wherein the acrylic polymer emulsified in water has a viscosity at 25 ℃ and 40 wt.% solids of 200 centipoise (cP) to 400cP andand/or (B) wherein the acrylic polymer has a gel content of about 50% to about 75%.

A third non-limiting example of the present disclosure is a method comprising emulsion polymerizing, in the presence of an initiator, a mixture of monomers comprising: 5 to 90 wt.% of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a monomer according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and one or more monomers selected from the group consisting of: 0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl; 0 to 10% by weight of a hydroxy acrylic monomer; and 0 to 10% by weight of a carboxylic acid containing monomer.

Drawings

The following figures are included to illustrate certain aspects of embodiments and should not be taken as exclusive embodiments. The disclosed subject matter is capable of considerable modification, alteration, combination, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent art and having the benefit of this disclosure.

Fig. 1 includes photographs of films after exposure to water according to the whitening test described herein.

Detailed description of the preferred embodiments

The present disclosure relates to emulsion acrylic Pressure Sensitive Adhesives (PSAs) having improved cohesion with maintained high adhesion. More specifically, the emulsion acrylic PSAs described herein utilize (meth) acrylate monomers derived from primary alcohols having carbon chains of varying carbon numbers and varying branching numbers. Such monomers are referred to herein as alkyl (meth) acrylate monomers.

Emulsion acrylic PSAs are typically synthesized using pure monomers. Acrylate monomers that impart adhesive properties typically include a straight carbon chain (e.g., butyl acrylate) or a single branchCarbon chains (e.g. 2-ethylhexyl acrylate and C)₁₂-C₃₂A (meth) acrylate monomer of a 2-alkyl alkanol). In contrast, the present disclosure uses a mixture of alkyl (meth) acrylate monomers having carbon chains (or carbon numbers) of different lengths and differently branched carbon chains including two or more branches. Without being limited by theory, it is believed that the diversification of carbon chain lengths and increased branching improves the cohesive properties of the acrylic PSA (including, for example, more than a 5-fold improvement in shear strength) while maintaining the adhesive properties of the acrylic PSA.

Definition and testing method

The term "acrylic" or "acrylic polymer" or "acrylic monomer" refers to a broad class of materials comprising the largest proportion of an α, β -ethylenically unsaturated carboxylic acid, a hydrocarbyl ester of an α, β -ethylenically unsaturated carboxylic acid, or mixtures thereof. The term "(meth) acrylate" refers to either methacrylate or acrylate. The term "(meth) acrylic" refers to methacrylic or acrylic.

As used herein, when a polymer is referred to as "comprising" a monomer, the monomer is present in the polymer in polymerized form of the monomer or in a derivative form of the monomer.

As used herein, the term "carbon number" refers to the number of carbons after the ester bond of a (meth) acrylate. For example, the carbon number of both 2-ethylhexyl acrylate and n-octyl acrylate is 8. The carbon number or carbon number range may be specified in the nomenclature of the alkyl (meth) acrylate monomer. For example, the alkyl (meth) acrylate monomer having 6 carbon atoms may be referred to as C (meth) acrylate₆An alkyl ester monomer. In another example, a mixture of alkyl (meth) acrylate monomers having a carbon number of 8 to 11 may be referred to as C (meth) acrylate_8-11An alkyl ester monomer.

As used herein, the term "carbon number distribution" refers to the relative weight percentage of each carbon number in the mixture of alkyl (meth) acrylate monomers. The carbon number distribution does not distinguish isomers having the same carbon number. Carbon number distribution was determined by gas chromatography using a capillary column with a non-polar stationary phase. More specifically, Agilent 6890N (HP-1 methylsiloxane, 30m × 530ID, dF ═ 0.88) was used running an HP-chemistry workstation and equipped with a5 μ L autosampler, flame ionization detector, and capillary column. The carrier gas was helium (4.2mL/min) and the detector gases were hydrogen (30-40mL/min), air (300-. Additional parameters are provided in table 1.

TABLE 1

The FID signal was normalized to the change in elution time such that the total area under the FID signal plot was 100 wt%. The area under the FID signal plot for each carbon number corresponding to the elution time range is the weight% of that carbon number in the carbon number distribution. The elution time range for each carbon number is determined using multiple standards such as isomers with different carbon numbers.

Carbon number and/or carbon number distribution measurements may be performed on the alkyl (meth) acrylate monomer or its alcohol precursor. It is assumed that the carbon number and carbon number distribution do not change when converting the alcohol to the (meth) acrylate.

As used herein, the term "branching index" refers to the number of branches in the alcohol precursor carbon chain of the alkyl (meth) acrylate monomer. For example, butyl acrylate has a branching index of 0, 2-ethylhexyl acrylate has a branching index of 1, and 2-ethyl-3-methylpentyl acrylate has a branching index of 2. When a mixture of alkyl (meth) acrylate monomers is reported, the branching index can be a decimal number representing the average branching index of the mixture.

Can pass through¹H solution state Nuclear Magnetic Resonance (NMR) spectroscopy measures the Branching Index (BI). It should be noted that the branching index is determined on the alcohol precursor and is assumed to not change upon conversion to the (meth) acrylate.

Quantitative recording in solution using a Varian Inova 500NMR spectrometer operating at 499.95MHz¹HNMR spectrogram. The spectra were recorded at 25 ℃ using an 8mm reverse probe, and nitrogen was used for all pneumatic devices. Approximately 500. mu.L of the alcohol precursor was dissolved in approximately 2mL of chloroform-d and 0.03% Tetramethylsilane (TMS).

Standard single pulse excitation uses 2 mus pulses to produce a 30 ° apex angle, 4s relaxation lag and 14Hz sample rotation. A total of 104064 data points and a residence time of 76.9. mu.s were obtained according to FID, resulting in an acquisition time of 4s and a spectral window of 13kHz (26 ppm). A total of 32 transients were recorded. This setting was chosen primarily for high resolution and generally quantified results for a wide range of materials. The FID is zero-filled, line-broadened, and the spectrum is phased, baseline corrected, and integrated as needed. Chemical shifts are referenced directly to TMS at 0 ppm.

The branching index (B) is calculated according to the following equation, where A is the integral of the spectrum between 0.4ppm and 0.9ppm and B is the integral of the spectrum between 3.0ppm and 3.9 ppm.

BI＝((2*A/3)/B)-1

The viscosity of the emulsion acrylic PSA and/or emulsified acrylic polymer is measured by a rotational viscometer in accordance with Chinese Standard GB/T2794-.

The gel fraction of the acrylic polymer represents the ratio of the insoluble content to the soluble content of the acrylic polymer. To determine the gel fraction, approximately 2g of the dried latex membrane was wrapped with a piece of filter paper (Whatman, qualitative, grade 102, 7cm diameter) and then extracted continuously with Tetrahydrofuran (THF) at 70 ℃ under reflux for 24h to remove soluble components. After extraction, the gel remaining in the filter paper was dried and weighed. The gel content was calculated according to the following equation, wherein W₀Is the weight of the filter paper without initial polymer, W₁Is the total weight of polymer and filter paper prior to extraction, and W₂Is the total weight of polymer and filter paper after extraction.

Acrylic PSA shear strength was measured according to Chinese Standard GB/T4581-2014, in which a strip of tape was applied to a standard steel panel under controlled pressure. The steel plate was mounted vertically, a proof mass was attached to the free end of the tape and the failure time was measured.

The acrylic PSA 180 peel strength was measured according to Chinese Standard GB/T2792-2014, where a strip of tape was applied to a stainless steel test panel with controlled pressure and allowed to dwell for 30 minutes. The tape was then peeled from the plate at an angle of 180 deg. at 300 mm/min. The force required to achieve peeling was recorded.

To evaluate whitening, a piece of acrylic PSA film (40 mm by 100mm BOPP film coated with an acrylic polymer having a thickness of 100 μm) was immersed in 500mL of deionized water in a water bath at 25 ℃. After a specified time, the film was taken out of the water and the appearance of the film was captured by a camera. Relative whitening was visually compared.

To evaluate water absorption, an acrylic PSA was coated on aluminum foil and dried by heating at 60 ℃ for 1 hour and 100 ℃ for 30 minutes to yield an acrylic polymer layer about 70 microns thick. The initial weight of the dried acrylic polymer/aluminum foil film was measured and then the water absorption ratio was measured by immersing the sample in water at room temperature for 24 hours. The sample was then taken out and the surface-adhered water was quickly wiped off with absorbent paper. The final weight was then measured and the amount of water absorbed over 24 hours was calculated (initial weight minus final weight).

The water contact angle (or static contact angle of water) on the acrylic polymer film was measured by OCA15 (Data Physics Instruments Company, germany) by the liquid drop method using a micro-syringe at room temperature and ambient pressure. The contact angle is the average of three separate test data at different locations on the polymer surface.

Acrylic polymer

The vinyl monomers described herein are those polymerizable by free radical reactions, preferably those materials commonly described as acrylic (e.g., alkyl (meth) acrylates and (meth) acrylic acid and generally include components from both (meth) acrylic acid and alkyl (meth) acrylates).

Acrylic of the present disclosure suitable for emulsion acrylic PSAThe polymer comprises (a)5 to 90% by weight of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a copolymer according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and (b) one or more monomers selected from the group consisting of: (i) 0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl; (ii)0 to 10% by weight of a hydroxy acrylic monomer having a carbon number of 1 to 10; and (iii)0 to 10% by weight of a carboxylic acid containing monomer. Optionally, the acrylic polymer of the present disclosure may further comprise 0.1 to 10 wt% of a vinyl monomer.

The acrylic polymer may comprise from 5 to 90 wt%, or from 10 to 80 wt%, or from 20 to 60 wt% of a mixture of alkyl (meth) acrylate monomers as described above for component (a).

The mixture of alkyl (meth) acrylate monomers may be described as a whole or as containing specific materials.

In characterizing the mixture as a whole, the mixture of alkyl (meth) acrylate monomers may have, for example, the following carbon number ranges: c_6-8Or C_6-9Or C_6-10Or C_6-11Or C_7-9Or C_7-10Or C_7-11Or C_7-12Or C_7-13Or C_8-10Or C_8-11Or C_8-12Or C_9-11Or C_9-12Or C_9-13Or C_10-12Or C_10-13Or C_10-14Or C_11-13Or C_11-14Or C_11-15. Further, in characterizing the mixture as a whole, a mixture of 90 wt% alkyl (meth) acrylate monomers may have, for example, the following carbon number ranges: c_6-8Or C_6-9Or C_6-10Or C_6-11Or C_7-9Or C_7-10Or C_7-11Or C_7-12Or C_7-13Or C_8-10Or C_8-11Or C_8-12Or C_9-11Or C_9-12Or C_9-13Or C_10-12Or C_10-13Or C_10-14Or C_11-13Or C_11-14Or C_11-15. Combinations of the above mixtures (disclosed in general or specifically) may be used. For example, (meth) acrylic acid C can be used_7-9Mixtures of alkyl ester monomers and (meth) acrylic acid C_8-11-a mixture of alkyl ester monomers as a mixture of alkyl (meth) acrylate monomers in the acrylic polymer described herein.

In further bulk characterizing the mixture, the mixture of alkyl (meth) acrylate monomers can have a branching index of 1.25 or greater, or 1.25 to 4, or 1.5 to 3, or 1.75 to 2.5, or 2 to 3.5.

Table 2 includes non-limiting examples of primary alcohol carbon number distributions suitable for use in preparing mixtures of alkyl (meth) acrylate monomers, where isohept-1-ol is C with 0-4 branches₇A mixture of isomers of primary alcohols.

TABLE 2

	Mixture 1	Mixture 2	Mixture 3	Mixture 4	Mixture 5
						Isoheptan-1-ol	0-10
Isooctan-1-ol	80-100	0-10
						Isononyl-1-ol	0-10	60-90	0-10
Isodecan-1-ol		10-30	80-100	1-10
						Isoundecane-1-alcohols			0-10	85-99
Isododecane-1-ol				0-5	15-25
						Isotridecyl-1-ol					55-79
Isotetradecan-1-ol					5-15
						Branching index	1.25-2	1.5-2.25	1.5-2.5	1.75-3	2.5-4

Combinations of the above mixtures may be used. For example, a 50:50 weight ratio of mixture 2 and mixture 4 can be used in preparing a mixture of alkyl (meth) acrylate monomers for the acrylic polymers described herein. In yet another example, a 75:25 weight ratio of mixture 4 and mixture 5 can be used in preparing the mixture of alkyl (meth) acrylate monomers for the acrylic polymers described herein.

In characterizing the components of the mixture, according to CH₂═C(R²)-(CO)-OR¹The carbon number of the first alkyl (meth) acrylate monomer(s) may be 6, or 7, or 8, or 9, or 10, or 11, or 12, or 13.

Furthermore, according to CH₂═C(R²)-(CO)-OR¹The first alkyl (meth) acrylate monomer of (a) may have a branching index of 2, or 3, or 4.

The mixture of alkyl (meth) acrylate monomers may contain any number of different alkyl (meth) acrylates based on CH₂═C(R²)-(CO)-OR¹The first alkyl (meth) acrylate monomer of (a). For example, the mixture of alkyl (meth) acrylate monomers may comprise 1 to 15, or 1 to 10, or 2 to 5, or 3 to 10 different alkyl (meth) acrylate monomers according to CH₂═C(R²)-(CO)-OR¹The first alkyl (meth) acrylate monomer of (a).

One or more different according to CH₂═C(R²)-(CO)-OR¹The first alkyl (meth) acrylate monomer of (a) may constitute from 15 wt% to 100 wt%, or from 25 wt% to 90 wt%, or from 25 wt% to 45 wt%, or from 35 wt% to 55 wt%, or from 50 wt% to 90 wt%% of alkyl (meth) acrylate monomer.

The acrylic polymer may comprise from 0 wt% to 80 wt%, or from 10 wt% to 70 wt%, or from 15 wt% to 60 wt%, or from 10 wt% to 50 wt% according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate.

According to CH₂═C(R⁴)-(CO)-OR³Specific examples of the second alkyl (meth) acrylate of (a) may include, but are not limited to, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, n-pentyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, isoundecyl (meth) acrylate, n-dodecyl (meth) acrylate, isododecyl (meth) acrylate, dodecyl (meth) acrylate, isopropyl, N-tridecyl (meth) acrylate, isotridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, isotetradecyl (meth) acrylate, C₁₂-C₃₂2-alkyl alkanols (e.g. C)₁₂-C₃₂Guerbet alkanol), and the like, and any combination thereof.

The acrylic polymer may comprise from 0 wt% to 10 wt%, or from 0.1 wt% to 8 wt%, or from 0.5 wt% to 5 wt% of the hydroxy acrylic monomer.

Examples of the hydroxy acrylic monomer may include, but are not limited to, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 4-hydroxymethylcyclohexyl methacrylate, polypropylene glycol mono (meth) acrylate, N-hydroxyethyl (meth) acrylamide, N-hydroxypropyl (meth) acrylamide, the like, and any combination thereof.

The acrylic polymer may comprise from 0 wt% to 30 wt%, or from 0.2 wt% to 20 wt%, or from 0.5 wt% to 10 wt% of carboxylic acid containing monomers.

Examples of carboxylic acid-containing monomers may include, but are not limited to, acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypropyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and the like, and any combination thereof.

The acrylic polymer may comprise from 0 wt% to 10 wt%, or from 0.1 wt% to 7 wt%, or from 0.5 wt% to 3 wt% of the vinyl monomer.

Examples of vinyl monomers can include, but are not limited to, (meth) acrylonitrile, (meth) acrylamide, vinyl acetate, vinyl propionate, vinyl laurate, vinylidene chloride, styrene, chlorostyrene, chloromethylstyrene, methylstyrene, other substituted styrenes, and the like, and any combination thereof.

The acrylic polymers described herein can have a gel content of from about 50% to about 80%, or from about 60% to about 75%.

Emulsion polymerization of acrylic polymers

The acrylic polymers described herein are typically synthesized by aqueous emulsion polymerization of selected monomers. Emulsion polymerization is a type of polymerization well known in the art. The reaction mixture generally includes an initiator, which may be any compound(s) or source for generating free radicals capable of initiating polymerization of the acrylic monomer. Water-soluble initiators are, for example, ammonium and alkali metal salts of peroxodisulfuric acid (for example sodium peroxodisulfate), hydrogen peroxide, or organic peroxides (for example tert-butyl hydroperoxide). Other suitable initiators include those known as reduction-oxidation initiator systems. Redox initiator systems consist of at least one, usually inorganic, reducing agent and an organic or inorganic oxidizing agent. The oxidizing component comprises the initiators already stated above, for example for emulsion polymerization. The reducing component comprises, for example, alkali metal salts of sulfurous acid (e.g., sodium sulfite, sodium bisulfite), alkali metal salts of metabisulfite (e.g., sodium metabisulfite), bisulfite addition compounds of aliphatic aldehydes and ketones (e.g., acetone bisulfite), or reducing agents such as hydroxymethanesulfinic acid and its salts, or ascorbic acid. Redox initiator systems can be used with soluble metal compounds whose metal component is capable of multiple valence states. Examples of redox initiator systems which are customary include ascorbic acid/iron (II) sulfate/sodium peroxodisulfate, tert-butyl hydroperoxide/sodium metabisulfite, tert-butyl hydroperoxide/Na hydroxymethanesulfinate. The individual components (e.g. the reducing component) may also be mixtures, examples being mixtures of the sodium salt of hydroxymethanesulfinic acid and sodium metabisulfite.

The initiator may be present in an amount of from 0.1 to 10 weight percent, or from 0.2 to 5 weight percent, or from 0.3 to 3 weight percent, based on the total weight of the monomers to be polymerized.

The process typically includes water to adjust the solids content of the emulsion. In some cases, it may be beneficial to buffer the pH of the solution between about 4 and about 7 by including some well-known buffering agents, such as sodium bicarbonate, potassium hydrogen phthalate, and the like.

Surfactants are typically used to aid in the formation of the monomers in the aqueous emulsion and to act as suspending agents for the solids in the final acrylic polymer, which are dispersed in the aqueous medium during and after polymerization, but this approach is not to be considered as limiting the invention. Surfactants useful in emulsion polymerization are well known and are present in amounts sufficient to place the reactants in an emulsion prior to reaction and to maintain the product in suspension after reaction. Examples of surfactants include, but are not limited to, alkylaryl sulfonates (e.g., sodium or calcium alkyl benzene sulfonates); fatty alcohol sulfates (e.g., sodium lauryl sulfate); phosphoric acid esters (e.g., sodium salts of mono-and diesters of orthophosphoric acid); sulfosuccinates; sodium salts of sulfated monoglycerides; sulfonates or sulfosuccinates of alkylpolyoxyalkene oxide condensates or of alkylphenol polyalkylene oxide condensates (e.g., ammonium salts of nonylphenol polyethylene oxide sulfonic acid); polyethylene oxide (e.g., aliphatic alcohols or alkyl phenols reacted with ethylene oxide, such as oleyl alcohol reacted with 15 moles of ethylene oxide); polyalkylene oxide block copolymers wherein the alkylene oxide blocks are those of, for example, ethylene oxide and propylene oxide; carboxylic acid amides (i.e., condensation products of fatty acids and hydroxyalkylamines) (e.g., diethanolamine condensates and polyoxyethylene fatty acid amides); carboxylic acid esters (e.g., glycerol esters, polyoxyethylene esters, and ethoxylated fatty acids and fatty acid glycol esters), and the like, and any combinations thereof. Of particular applicability are blends of anionic and nonionic surfactants having a hydrophilic-lipophilic balance (HLB) of from 14 to 42, or from 35 to 40. Although the range of surfactants is well known, the amount of surfactant can range from 0.1 wt% to 10 wt%, or from 0.2 wt% to 5 wt%, based on the total weight of the monomers to be polymerized.

The molecular weight of such acrylic polymers is generally controlled by the commonly known mono-olefin chain transfer agents in the polymerization mixture. If used, the amount of chain transfer agent can range from 0.01 wt.% to 0.5 wt.%, or 0.01 wt.% to 0.2 wt.%, based on the total weight of the monomers to be polymerized. Suitable chain transfer agents are, for example, organic compounds containing sulfur in bonded form (e.g. compounds having a thiol group), aliphatic and/or araliphatic halogen compounds, aliphatic and/or aromatic aldehydes, unsaturated fatty acids (e.g. oleic acid), dienes having a non-conjugated double bond (e.g. divinylmethane, terpinolene or vinylcyclohexene), hydrocarbons having a readily abstractable hydrogen atom (e.g. toluene), organic acids and/or their salts (e.g. formic acid, sodium formate, ammonium formate), alcohols (e.g. isopropanol) and phosphorus compounds (e.g. sodium hypophosphite).

For the reaction, the monomers are dispersed in an aqueous medium using a surfactant to form an emulsion at ambient temperature. The reaction mixture (e.g., comprising some or all of the monomer emulsion, some or all of the initiator, and some or all of the chain transfer agent) is then formed, typically placed in a reaction vessel evacuated of oxygen by purging with nitrogen or other inert gas, and polymerized with agitation in a closed vessel under the enclosure of nitrogen or other inert gas. The initiator and chain transfer agent are added to the reaction mixture in amounts and for a time to achieve the desired molecular weight.

For example, the emulsion polymerization may be carried out at a temperature in the range of 30 ℃ to 130 ℃, preferably 50 ℃ to 90 ℃. The emulsion polymerization may be carried out batchwise or in a feed process comprising a gradient or staged process, with a feed process being preferred. During the feed, a portion, typically 5 to 10 wt% of the monomer pre-emulsion, is added to the reactor along with a portion of initiator and optionally surfactant and heated to the polymerization temperature to initiate polymerization. The remaining monomer pre-emulsion and initiator are fed to the reactor at the polymerization temperature, typically in 2 to 5 hours. Optionally, polymer emulsion seed crystals may be added as an initial charge for polymerization to better control the particle size of the polymer emulsion.

Methods for adding initiators to emulsion polymerization reactions are known to those of ordinary skill in the art. It may be added to the reactor as an initial charge in its entirety, or fed continuously throughout the reaction, or added in stages or gradients, or a combination of these addition methods as non-limiting examples.

To reduce the amount of residual monomer at the end of the emulsion polymerization (typically after completion of the monomer pre-emulsion feed and initiator feed), the polymerization reaction may be maintained at the polymerization temperature for a longer period of time, typically 1 to 3 hours, to consume residual monomer, optionally with a small amount of initiator at this stage.

Once the reaction is complete, the solid in the form of the dispersed acrylic polymer is cooled to room temperature and the dispersed acrylic polymer is separated from the coagulum formed during the polymerization, typically by filtration (e.g., using a 200 mesh sock filter).

The filtrate is then used in a pressure sensitive adhesive.

Pressure sensitive adhesive and use

The pressure sensitive adhesive may comprise an emulsion of one or more of the acrylic polymers described herein. The pressure sensitive adhesive may be comprised of an emulsion of one or more of the acrylic polymers described herein.

Optionally, the pressure sensitive adhesive may include one or more additives. Examples of additives may include, but are not limited to, fillers, dyes, flow control agents, thickeners (e.g., associative thickeners), defoamers, crosslinkers, plasticizers, pigments, wetting agents, tackifiers (e.g., tackifying resins), and the like, and any combination thereof.

If included, the additives may be individually present in an amount of 0.05 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on the solids weight of the polymer emulsion. However, if a tackifier is used, it may be up to 50 weight percent, based on the solid weight of the polymer emulsion.

The properties of acrylic PSAs depend, among other things, on the composition of the acrylic polymer, the composition and concentration of additives, and the like. Accordingly, the following properties of the acrylic PSA are considered non-limiting.

The acrylic PSAs described herein can have a viscosity at 25 ℃ and 40 wt.% solids of 200 to 400 centipoise (cP), or 250 to 350cP, or 300 to 400 cP.

The acrylic PSAs described herein can have a shear strength of 50 hours or greater, or 75 hours or greater, or 100 hours or greater, or 150 hours or greater, or 200 hours or greater. The upper limit is not limited because the time to achieve shear according to the test methods described herein is very long if it is actually sheared. The test is usually stopped after 200 hours.

The acrylic PSA described herein may have a density of 15 newtons/25 mm (N/25mm) (600 kg/s)²) To 25N/25mm (1000 kg/s)²) Or 17N/25mm (680 kg/s)²) To 22N/25mm (880 kg/s)²) The peel strength of (3).

The acrylic PSAs described herein can have a water absorption rate of 40 wt%/24 hours or less, or 30 wt%/24 hours or less, or 25 wt%/24 hours or less, or 20 wt%/24 hours or less.

The acrylic PSAs described herein can have a water contact angle of 80 ° to 98 °, or 85 ° to 97 °, or 90 ° to 98 °.

The emulsion comprising the acrylic polymer described herein can be coated on a substrate film used as, for example, an adhesive tape. The coated substrate is typically dried by circulating hot air at 50 ℃ to 110 ℃ for 2 to 10 minutes. Other processing parameters for such coated substrates will be readily appreciated by those skilled in the art. The dried and cured coating produces an adhesive film suitable for PSA applications. Suitable substrates for use in conjunction with the PSA may include, but are not limited to, metallic materials, plastic materials, paper materials, cloth materials, and the like. Examples of metal substrates may include, but are not limited to, aluminum, copper, and steel. Examples of plastic substrates may include, but are not limited to, polyesters, polyolefins, polyethylene terephthalate, and the like.

The acrylic polymers described herein may be used in PSA applications including, but not limited to, labels, graphics, tapes, signs, display components, and the like.

Additionally, adhesives formed using the acrylic polymers described herein may be used in non-pressure sensitive adhesives, including but not limited to laminating adhesives, adhesives for woven and non-woven fabrics, adhesives for pressed wood production (e.g., in plywood or engineered wood), and the like.

Example embodiments

A first non-limiting example of the present disclosure is an acrylic polymer comprising: 5 to 90 wt.% of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a monomer according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and one or more monomers selected from the group consisting of: 0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl; 0 to 10% by weight of a hydroxy acrylic monomer; and 0 to 10% by weight of a carboxylic acid containing monomer.

A second non-limiting example of the present disclosure is a pressure sensitive adhesive comprising: an acrylic polymer emulsion polymerized in water, the acrylic polymer comprising: 5 to 90 wt.% of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a monomer according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and one or more monomers selected from the group consisting of: 0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl; 0 to 10% by weight of a hydroxy acrylic monomer; and 0 to 10% by weight of a carboxylic acid containing monomer. The pressure sensitive adhesive may optionally be further characterized by: (A) wherein the acrylic polymer emulsified in water has a viscosity at 25 ℃ and 40 weight percent solids of from 200 centipoise (cP) to 400cP and/or (B) wherein the acrylic polymer has a gel content of from about 50% to about 75%.

A third non-limiting example of the present disclosure is a method comprising emulsion polymerizing, in the presence of an initiator, a mixture of monomers comprising: 5 to 90 wt.% of a mixture of alkyl (meth) acrylate monomers, wherein the mixture comprises a monomer according to CH₂═C(R²)-(CO)-OR¹A first alkyl (meth) acrylate monomer of (1), wherein R¹Is an alkyl group having a carbon number of 6 to 13 and a branching index of 2 to 4 and R²Is hydrogen or methyl; and one or more monomers selected from the group consisting of: 0% to 80% by weight of a base according to CH₂═C(R⁴)-(CO)-OR³A second alkyl (meth) acrylate of (2), wherein R³Is an alkyl group having a carbon number of 1 to 14 and a branching index of 0 to 1 and R⁴Is hydrogen or methyl; 0 to 10% by weight of a hydroxy acrylic monomer; and 0 to 10% by weight of a carboxylic acid containing monomer.

Each of the above examples optionallyIncluding one or more of: element 1: wherein the acrylic polymer or mixture of monomers further comprises: 0.1 to 10% by weight of a vinyl monomer selected from: (meth) acrylonitrile, (meth) acrylamide, vinyl acetate, vinylidene chloride, styrene, and methylstyrene; element 2: wherein the mixture of alkyl (meth) acrylate monomers is present at 20 wt% to 60 wt%; element 3: wherein the second alkyl (meth) acrylate is present at 10 wt% to 50 wt%; element 4: wherein the hydroxyacrylic monomer is present at 0.3 wt% to 8 wt%; element 5: wherein the carboxylic acid containing monomer is present at 0.2 wt% to 8 wt%; element 6: wherein 90 wt% of the mixture of alkyl (meth) acrylate monomers has a carbon number range selected from: c_6-8、C_6-9、C_6-10、C_6-11、C_7-9、C_7-10、C_7-11、C_7-12、C_7-13、C_8-10、C_8-11、C_8-12、C_9-11、C_9-12、C_9-13、C_10-12、C_10-13、C_10-14、C_11-13、C_11-14And C_11-15(ii) a Element 7: wherein the mixture of alkyl (meth) acrylate monomers has a branching index of 1.25 to 4; element 8: wherein the mixture of alkyl (meth) acrylate monomers is derived from an alcohol mixture having a composition of the mixture according to one or more of table 2; element 9: wherein the mixture of alkyl (meth) acrylate monomers further comprises at least one monomer according to CH different from the first alkyl (meth) acrylate monomer₂═C(R²)-(CO)-OR¹Alkyl (meth) acrylate monomers of (a); element 10: element 9 and wherein the first alkyl (meth) acrylate monomer and the at least one alkyl (meth) acrylate monomer, in total, comprise a mixture of 15 to 100 weight percent of the alkyl (meth) acrylate monomer; and element 11: element 9 and wherein the first alkyl (meth) acrylate monomer and the at least one alkyl (meth) acrylate monomer, in total, comprise a mixture of 30 to 90 weight percent alkyl (meth) acrylate monomer. Such a combinationExamples may include, but are not limited to, combinations of two or more of elements 1-5 and optionally further combinations with element 8; elements 6 and 7 in combination and optionally in further combination with one or more of elements 1-5; element 9 (and optionally element 10 or 11) in combination with one or more of elements 1-5 and optionally in further combination with one or more of elements 6-8; and one or more of elements 6-8 in combination with element 9 (and optionally element 10 or 11).

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties (e.g., branching index, reaction conditions, and so forth) used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the embodiments of the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

One or more illustrative embodiments including the embodiments of the invention disclosed herein are set forth herein. In the interest of clarity, not all features of a physical implementation are described or shown in this application. It should be appreciated that in the development of a physical embodiment, including embodiments of the present invention, numerous implementation-specific decisions must be made in order to achieve the developer's goals, such as compliance with system-related, business-related, government-related, and other constraints, which will vary from one implementation to another. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in this art having the benefit of this disclosure.

Although the compositions and methods are described herein in terms of "comprising" various components or steps, the compositions and methods can also "consist essentially of" or "consist of" the various components and steps.

In order to facilitate a better understanding of embodiments of the present invention, the following examples of preferred or representative embodiments are given. The following examples should not be construed in any way to limit or define the scope of the present invention.