Adhesion promoter composition
阅读说明：本技术 增粘剂组合物 (Adhesion promoter composition ) 是由 J·B·宾德 S·普加里 于 2020-01-31 设计创作，主要内容包括：一种增粘剂聚合添加剂,其包含具有以下的乳液聚合反应产物：(a)至少一种芳香族单体；(b)至少一种丙烯酸酯或甲基丙烯酸酯单体；和(c)至少一种链转移剂；以及一种增粘丙烯酸粘附剂组合物,其包含(I)至少一种丙烯酸粘附剂聚合物；和(II)上述增粘剂聚合添加剂。(A tackifier polymeric additive comprising an emulsion polymerization reaction product having: (a) at least one aromatic monomer; (b) at least one acrylate or methacrylate monomer; and (c) at least one chain transfer agent; and a tackified acrylic adhesive composition comprising (I) at least one acrylic adhesive polymer; and (II) the above tackifier polymeric additive.)
1. A tackifier polymeric additive comprising an emulsion polymerization reaction product having:
(a) at least one monomer having a homopolymer glass transition temperature greater than 80 ℃;
(b) at least one monomer selected from monomers having the following general formula (I):
R1-CH ═ CR 2-COOR 3 formula (I)
Wherein R1 is selected from the group consisting of hydrogen, aliphatic and aromatic radicals; wherein R2 is selected from the group consisting of hydrogen, aliphatic and aromatic radicals; and wherein R3 is selected from the group consisting of hydrogen, aliphatic, aromatic; and
(c) at least one chain transfer agent; wherein the tackifier polymeric additive has a polymer miscibility fraction greater than 0.
2. The tackifier polymeric additive of claim 1, wherein the tackifier polymeric additive has a glass transition temperature of greater than 0 ℃, a number average molecular weight of 1,200 daltons (Dalton) to 20,000 daltons, and a polymer miscibility fraction of greater than 0.
3. The tackifier polymeric additive of claim 1, wherein the monomer having a homopolymer glass transition temperature greater than 80 ℃ is selected from the group consisting of: aromatic monomers, methyl methacrylate and mixtures thereof.
4. The tackifier polymeric additive of claim 1, wherein the at least one monomer of component (b) is an acrylate monomer or a methacrylate monomer.
5. The tackifier polymeric additive of claim 4, wherein component (b) is selected from the group consisting of: n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, and mixtures thereof.
6. The tackifier polymerization additive of claim 1, wherein the at least one chain transfer agent is selected from the group consisting of: alkyl mercaptans, esters of mercaptans, ethanol, and mixtures thereof.
7. A method for making a tackifier polymeric additive comprising blending:
(a) at least one aromatic monomer having a homopolymer glass transition temperature greater than 80 ℃;
(b) at least one acrylate or methacrylate monomer; and
(c) at least one chain transfer agent; wherein the tackifier polymeric additive has a polymer miscibility fraction greater than 0.
8. The method of claim 7, wherein the blending is performed by emulsion polymerization.
9. A tackified acrylic adhesive composition, comprising:
(I) at least one acrylic adhesive polymer;
(II) at least one tackifier polymer additive according to claim 1; and
(III) optionally water.
10. The tackified acrylic adhesive composition of claim 9, wherein the tackified acrylic adhesive composition has a peel adhesion of 90% to 1,000% relative to the non-tackified adhesive without a significant decrease in cohesion (shear resistance); and wherein the cohesive force (shear resistance) of the tackified acrylic adhesive composition is greater than 71 hours.
11. A process for making a tackified acrylic adhesive composition comprising blending:
(I) at least one acrylic adhesive polymer; and
(II) at least one tackifier polymer additive according to claim 1.
12. An article comprising the tackified acrylic adhesive composition of claim 9.
Technical Field
The present invention relates to a tackifier polymeric additive; and more particularly, the present invention relates to a tackifier polymeric additive for adhesives
Background
Pressure sensitive adhesives are characterized by both the adhesion of the adhesive to the substrate (peel, tack) and the cohesive strength within the adhesive (shear resistance). However, adhesion and cohesive strength are two generally inversely related properties. For certain applications, both adhesion and cohesion need to be improved; and both of these characteristics are difficult to achieve by conventional polymer design or additive methods.
One common method of increasing the adhesion of pressure sensitive adhesives is to add a polymeric additive, known as a tackifier, to the adhesive. Tackifiers are used to increase the self-adhesion (tack) of an adhesive. Several classes of polymers are known to have been used as tackifiers, such as rosins and rosin derivatives, terpene resins, and hydrocarbon resins. Nevertheless, these known tackifiers suffer from several problems, including, for example, poor compatibility with acrylic adhesive polymers, undesirable color, and significant reduction in cohesive strength of formulated adhesives with such tackifiers. Furthermore, the above known tackifiers are not currently available.
An alternative method of providing an adhesive with a tackifier is to make the tackifier polymer from a vinyl aromatic or (meth) acrylic monomer. For example, U.S. Pat. No. 4,912,169 describes adhesive polymers tackified with polymeric additives, wherein the polymeric additives have been prepared from (meth) acrylic acid C1-C20Alkyl esters and cyclic alkyl (meth) acrylates, olefinic acids and other ethylenically unsaturated monomers; and wherein the polymeric additive has a molecular weight of less than: (A)<) A number average molecular weight (Mn) of 35,000 and greater than: (C:)>) Softening point at 40 degrees Celsius (. degree. C.). These manufactured tackifier polymers solve the problem of undesirable color and the usability of various resins. However, formulated adhesives using the manufactured tackifier polymers still suffer from a significant decrease in cohesive strength. In addition, it is difficult to obtain several raw materials suitable for making polymeric additives, such as isobutyl methacrylate (IBMA) and formazanIsobornyl acrylate (IBOMA).
Several prior art references disclose the use of tackifier materials in various polymer compounds, including, for example, U.S. patent nos. 4,912,169; U.S. Pat. No. 5,028,484; 5,236,991 No. C; 6,989,413 No. C; 7,262,242 No. C; 7,723,466 No. C; 7,332,540 No. C; 9,605,188 No. C; and No. 9,657,204; U.S. patent application publication No. US 20020055587; CN 1429259; WO 2016160250; and EP 2847290. However, the above references do not disclose a tackifier material that combines the following qualities: (1) compatibility with the adhesive polymer; (2) a glass transition temperature (Tg) high enough (e.g., >0 ℃) not to significantly reduce shear; and (3) gradually increasing the adhesion (peel or tack) of the adhesive upon formulation. In some known adhesive compositions, the adhesion of the adhesive is reduced to an undesirably low level, such that the adhesion is lower than that of an adhesive without the tackifier material.
Thus, there remains a need in the adhesive industry for a tackifier material: (1) can be produced using readily available raw materials, (2) can be prepared using standard emulsion polymerization equipment rather than specialized equipment; (3) good compatibility with acrylic adhesive polymers; (4) the peel and tacky adhesive properties of the adhesive can be increased; and (5) does not significantly reduce the shear resistance properties of the adhesive.
Disclosure of Invention
In one general embodiment, the present disclosure is directed to a tackifier polymeric additive comprising an emulsion polymerization reaction product having: (a) at least one styrene, methyl methacrylate, alpha-methylstyrene or other aromatic monomer whose homopolymer Tg is >80 ℃; (b) at least one acrylate or methacrylate monomer; and (c) at least one Chain Transfer Agent (CTA). The tackifier polymeric additive exhibits several beneficial properties, for example, the Tg of the tackifier polymeric additive may be >0 ℃, the Mn of the tackifier polymeric additive may be from 1,200 daltons (Da) to 20,000Da, and the polymer miscibility fraction of the tackifier polymeric additive may be > 0. The selection of monomers, Tg, Mn, and polymer miscibility fractions significantly distinguishes the tackifier polymeric additive of the present invention from known additives.
Additionally, tackifier polymeric additives made according to the inventive principles described herein unexpectedly increase the adhesive properties of the adhesive composition without significantly reducing the shear resistance properties of the adhesive composition; and the tackifier polymeric additive of the present invention has good compatibility with acrylic adhesive polymers. In addition, the raw materials used to prepare the tackifier polymeric additive of the present invention are readily available materials.
In another general embodiment, the present invention is directed to a tackified acrylic adhesive composition comprised of (I) at least one acrylic adhesive polymer and (II) at least one of the above tackifier polymer additives. Advantageously, the adhesion of the tackified adhesive composition of the present invention can be increased without significantly reducing the cohesion (shear resistance) of the tackified adhesive composition of the present invention.
Detailed Description
"adhesion" herein means pressure sensitive adhesive peel adhesion test or loop tack test as measured by PSTC 101 or PSTC 16.
"cohesion" or "shear resistance" as measured by PSTC 107 herein means the pressure sensitive adhesive shear resistance test.
By "polymer miscibility fraction" herein is meant a calculated measure of the miscibility of an adhesion promoter polymeric additive with an acrylic adhesive polymer based on the monomer composition of the adhesion promoter polymeric additive, the Mn of the adhesion promoter polymeric additive, and optionally the monomer composition of the acrylic adhesive polymer, with reference to the adhesion promoter polymeric additive.
In a broad embodiment, the invention comprises a tackifier polymeric additive that is an emulsion polymerization reaction product having: (a) at least one monomer, such as styrene, methyl methacrylate, alpha-methylstyrene or other aromatic monomers whose homopolymer Tg is >80 ℃; (b) at least one acrylate or methacrylate monomer; and (c) at least one chain transfer agent; such that the glass transition temperature (Tg) >0 ℃, the Mn of the adhesion promoter polymeric additive is from 1,200Da to 20,000Da, and the polymer miscibility fraction of the adhesion promoter polymeric additive is > 0.
Component (a) of the tackifier polymeric additive of the present invention comprises, for example, at least one monomer having a homopolymer Tg >80 ℃. Homopolymer Tg of the monomer can be measured using a midpoint temperature using Differential Scanning Calorimetry (DSC) as described, for example, in ASTM 3418/82.
In some embodiments, the monomer having a homopolymer Tg >80 ℃ may be an aromatic monomer known in the art that is capable of polymerizing with at least one acrylate or methacrylate monomer to produce the tackifier resin. The term "aromatic monomer" means a monomer containing at least one unsaturated cyclic hydrocarbon group containing one or more rings. Examples of aromatic monomers suitable for use in the present invention include, but are not limited to, olefin-substituted aromatics such as styrene, alpha-methylstyrene, vinyltoluene, indene, methylindene, divinylbenzene, dicyclopentadiene, methyl-dicyclopentadiene, and mixtures thereof. In a preferred embodiment, the aromatic monomer may be styrene. In other embodiments, the monomer with a homopolymer Tg >80 ℃ may be methyl methacrylate. In other embodiments, two or more monomers having a homopolymer Tg >80 ℃ may be used in combination.
In general, in one embodiment, the homopolymer Tg of the monomer can be >80 ℃, in another embodiment 80 ℃ to 110 ℃, and in yet another embodiment 95 ℃ to 160 ℃.
The amount of monomer used to make the tackifier polymeric additive and having a homopolymer Tg >80 ℃ may be, for example, 80 to 10 weight percent (wt%) in one embodiment, 75 to 20 wt% in another embodiment, and 75 to 30 wt% in yet another embodiment. Above and below the above amount ranges, the tackifier polymeric additive will not meet the compatibility and Tg requirements of the present invention.
Component (b) of the tackifier polymeric additive of the present invention comprises, for example, at least one acrylate or methacrylate monomer known in the art which is capable of polymerizing with monomers having a homopolymer Tg >80 ℃.
In one embodiment, the acrylate monomer may be a monomer having the following general formula (I):
R1-CH ═ CR 2-COOR 3 formula (I)
Wherein R1 is selected from the group consisting of hydrogen, aliphatic and aromatic radicals; wherein R2 is selected from the group consisting of hydrogen, aliphatic and aromatic radicals; and wherein R3 is selected from the group consisting of hydrogen, aliphatic, aromatic.
The term "aliphatic" is defined as a straight or branched chain arrangement of constituent carbon atoms and includes, but is not limited to, alkanes, alkenes, dienes, and alkynes. The aliphatic group can contain functional groups such as, but not limited to, hydroxyl, cycloaliphatic, acid, epoxide, amide, acrylonitrile, and acrylate. The aliphatic group may have 1 to 20 carbon atoms in one preferred embodiment, and 1 to 12 carbon atoms in another embodiment.
The term "aromatic group" means at least one unsaturated cyclic hydrocarbon group containing one or more rings. The aromatic group may be selected from the group consisting of: unsubstituted and substituted aromatic radicals of a constituent having up to 6 carbon atoms. In a preferred embodiment, the aromatic group may have 6 to 20 carbon atoms. The aromatic group may contain functional groups such as, but not limited to, hydroxyl, cycloaliphatic, acid, epoxide, amide, acrylonitrile, and acrylate. In some embodiments, the above functional groups may result in acrylate monomers having more than one reactive site for polymerization or other reactions. In a preferred embodiment, both R1 and R2 of the acrylate monomer of formula (I) are hydrogen. When the acrylate monomer is a methacrylic compound, R2 is CH3A group.
In other embodiments, for acid functional monomers, R3 of formula (I) can be hydrogen, forming monomers such as acrylic acid and methacrylic acid. The acid functional monomer may also include difunctional components such as maleic acid and fumaric acid. And in other embodiments, the acid functional monomer may comprise the anhydride form of the above components.
In yet another embodiment, the functional group can be found in the R3 group of formula (I). Suitable examples for use in the present invention may include hydroxyethyl acrylate, glycidyl methacrylate, and 1, 3-butanediol dimethacrylate.
Examples of suitable acrylate or methacrylate monomers suitable for use in the present invention may include esters of monoethylenically unsaturated carboxylic acids having from 3 carbon atoms to 24 carbon atoms, particularly esters of acrylic acid and methacrylic acid, including methyl acrylate ("MA"), ethyl acrylate ("EA"), butyl acrylate ("BA"), butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, isoamyl acrylate, isoamyl methacrylate, 2-ethylhexyl methacrylate, isooctyl acrylate, isooctyl methacrylate, n-propyl acrylate, isopropyl acrylate, methyl methacrylate ("MMA"), decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, and mixtures thereof.
The following are also applicable to the present invention: alpha, beta-ethylenically unsaturated mono-or dicarboxylic acids of 3 to 6 carbon atoms, such as acrylic acid ("AA"), methacrylic acid, itaconic acid, fumaric acid, maleic acid, and mixtures thereof; and anhydrides of monoolefinically unsaturated dicarboxylic acids such as maleic anhydride, itaconic anhydride and mixtures thereof.
Other tackifier polymeric additives suitable for use in the present invention may comprise other monomers including hydroxyalkyl acrylates and methacrylates, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, and mixtures thereof.
In some preferred embodiments, the acrylate or methacrylate monomers may comprise n-butyl acrylate, t-butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, and mixtures thereof. In other embodiments, two or more acrylate or methacrylate monomers may be used in combination.
The amount of acrylate or methacrylate monomer used to make the tackifier polymeric additive may be, for example, from 90 to 20 weight percent in one embodiment, from 80 to 25 weight percent in another embodiment, and from 70 to 25 weight percent in yet another embodiment. Above and below the above ranges of amounts, it will be difficult to achieve the Tg and compatibility characteristics of the tackifier polymeric additive of the present invention.
The acrylate or methacrylate monomer (component (b)) itself exhibits some advantageous properties before it is used to make the tackifier polymeric additive. For example, monomers having the acid functionality described above can improve polymer stability in end use applications. Monomers having more than one reactive site may allow for branching or crosslinking reactions.
Component (c) of the tackifier polymeric additive of the present invention comprises, for example, at least one CTA. Examples of chain transfer agents useful in the present invention include long chain alkyl mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan (n-DDM); 3-mercaptopropionic acid and esters thereof, such as methyl 3-mercaptopropionate (MMP) and butyl 3-mercaptopropionate; carbon tetrachloride, tetrachloroethylene, and trichlorobromoethane; and mixtures thereof.
In some embodiments, the chain transfer agent may be a dithioester or trithioester known to act as a chain transfer agent in free radical polymerization. Examples of chain transfer agents useful in the present invention include 2- (dodecylthiocarbonyl-thionyl) -2-methylpropionic acid, poly (ethylene glycol) methyl ether (4-cyano-4-pentanoic acid dodecyltrithiocarbonate), 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4- (phenylthiocarbonylthio) pentanoic acid, 2-phenyl-2-propylbenzodithiol, 2-cyano-2-propylbenzodithiol and mixtures thereof.
The amount of chain transfer agent used to make the tackifier polymerization additive may be, for example, an amount selected to achieve a target Mn of the tackifier polymerization additive according to the following relationship, e.g., 1,200Da to 20,000 Da:
wherein N isCTAIs CTA mole number, NMonomerIs the mole number of the monomer, ziIs a fraction of the i-th monomerQuantum, χiIs the mole fraction of the ith monomer, Mn is the target Mn for the adhesion promoter polymeric additive, and zCTAMolecular weight of CTA. Depending on the CTA and monomer selected, the moles of CTA per mole of monomer can be selected to achieve the target Mn.
The amount of chain transfer agent used to make the tackifier polymerization additive may depend on the amount of the particular CTA used to make the additive and other components in the additive. However, as an illustrative example and therefore without limitation, when the CTA used in the present invention is, for example, n-DDM, the amount of chain transfer agent may be 1 to 17 weight percent; or when the CTA used in the present invention is, for example, MMP, the amount of chain transfer agent can be 0.6 wt% to 10 wt%.
The CTA itself exhibits some advantageous properties before it (component (c)) is used to make the tackifier polymeric additive. For example, the characteristics of CTA may include solubility in water such that it can be transported from the aqueous phase through the aqueous phase to the growing polymer particles in an emulsion polymerization, or such that it primarily contributes to the polymerization in the aqueous phase. Other chain transfer agents may have lower solubility and greater solubility in organic solvents such that they act primarily on polymerization in monomer-expanded polymer particles. Other chain transfer agents may support reversible transfer reactions to achieve reversible addition fragmentation chain transfer (RAFT) polymerization.
In other embodiments, the tackifier polymeric additive of the present disclosure may comprise, for example, at least one or more additional optional components, compounds, or agents. In one embodiment, further component (d) suitable for use in the present invention may comprise, for example, water.
The amount of water when used to make the tackifier polymeric additive may be, for example, from 25 to 80 weight percent in one embodiment, from 30 to 75 weight percent in another embodiment, and from 30 to 60 weight percent in yet another embodiment. In another embodiment, one or more optional surfactants may be added to the tackifier polymeric additive. Examples of suitable exemplary surfactants according to the present invention may include, but are not limited to, cationic surfactants; an anionic surfactant; a zwitterionic surfactant; a nonionic surfactant; and combinations thereof. Examples of cationic surfactants suitable for use in the present invention may include, but are not limited to, quaternary amines; lauryl-pyripyropene chloride; cetyl dimethylamine acetate; alkyldimethylbenzyl ammonium chlorides wherein the alkyl group has from 8 to 18 carbon atoms; and mixtures thereof. Examples of anionic surfactants suitable for use in the present invention may include, but are not limited to, sulfonates; a carboxylate; a phosphate salt; and mixtures thereof. Examples of nonionic surfactants suitable for use in the present invention may include, but are not limited to, block copolymers containing ethylene oxide and silicone surfactants, such as ethoxylated straight and branched chain aliphatic alcohols; ethoxylated fatty acids; a sorbitan derivative; a lanolin derivative; an alkoxylated polysiloxane; and mixtures thereof.
The amount of any optional surfactant when used in making the tackifier polymeric additive may be, for example, from 0 wt% to 5 wt% in one embodiment, from 0.01 wt% to 3 wt% in another embodiment, and from 0.1 wt% to 2 wt% in another embodiment.
In other embodiments, the tackifier polymeric additive of the present disclosure may comprise, for example, at least one or more initiators. Examples of initiators suitable for use in the present invention may include thermal initiators; a redox system initiator; or mixtures thereof. Examples of thermal initiators suitable for use in the present invention may include, but are not limited to, sodium persulfate; ammonium persulfate; and mixtures thereof. When the initiator used in the present invention is a redox system initiator, the reducing agent used may be, for example, ascorbic acid; hyposulfite or erythorbic acid; and the oxidizing agent used may be, for example, peroxides; or a persulfate. Generally, in one embodiment, the amount of initiator used may be >1 weight percent, based on the total weight of monomers in the monomer mixture.
Generally, the process for making the tackifier polymeric additive comprises copolymerizing (a) at least one monomer having a homopolymer Tg >80 ℃ with (b) at least one acrylate or methacrylate monomer in the presence of (c) at least one chain transfer agent and any desired optional compounds, additives or agents.
In a preferred embodiment, the tackifier polymeric additive may be prepared by an emulsion polymerization process. The parameters of the emulsion polymerization can be adjusted by those skilled in the art of emulsion polymerization. For example, one or more of the monomers and chain transfer agents may be emulsified in the aqueous phase prior to emulsion polymerization. The polymerization can be started with new particles formed by polymerization of the monomers or in the presence of a previously prepared seed polymer. The initiator may be added at the beginning of the polymerization or according to the feed schedule. In another preferred embodiment, the tackifier polymerization additive may be prepared by a semi-batch emulsion polymerization process wherein a mixture of monomers is fed gradually into the polymerization reactor.
The tackifier polymeric additives of the present invention have several beneficial properties and properties, including, for example, higher Tg, higher Mn, and higher polymer miscibility fraction.
For example, the Tg of the tackifier polymeric additive may be >0 ℃ in one embodiment; from 0 ℃ to 50 ℃ in another embodiment, and from 10 ℃ to 50 ℃ in yet another embodiment; and in yet another embodiment from 15 ℃ to 40 ℃. The Tg of the tackifier polymeric additive may be measured by midpoint temperature using a Differential Scanning Calorimetry (DSC) curve as described, for example, in ASTM 3418/82. If the Tg of the tackifier polymeric additive is <0 deg.C, then it is likely that the shear of an adhesive formulated from the tackifier polymeric additive and the acrylic adhesive will be <70 hours (h).
For example, the Mn of the tackifier polymeric additive may be 1,200Da to 20,000Da in one embodiment; 1,500Da to 15,000Da in another embodiment; from 1,800Da to 10,000Da in yet another embodiment; and in yet another embodiment from 2,500Da to 10,000 Da. As the molecular weight of the tackifier polymeric additive becomes higher, the compatibility and adhesion of the tackifier polymeric additive may become lower. As the molecular weight of the tackifier polymeric additive becomes lower, the Tg of the additive may become lower and the cohesive strength of the final adhesive film tends to be lower. The Mn of the tackifier polymeric additive may be measured by Gel Permeation Chromatography (GPC) similar to size exclusion chromatography.
Most emulsion polymerization additives composed of styrene and methyl methacrylate do not act as tackifiers (do not increase adhesion). However, in the present invention, by selecting additives based on the polymer miscibility fraction, excellent tackifiers can be obtained. More specifically, the polymer miscibility fraction of the tackifier polymeric additive of the present invention may be calculated using the following equation (I):
wherein V is selected to be 100cm3Per mol; r is a universal gas constant; t is selected to be 298K; deltaD1、δP1And deltaH1Hansen Solubility Parameters (HSP) for tackifier additive polymers; deltaD2、δP2And deltaH2HSP for an acrylic adhesive polymer to be blended with a tackifier additive polymer; and DpIs the average degree of polymerization of the tackifier additive polymer. In some embodiments, δD2、δP2And deltaH2May be selected for the particular acrylic adhesive polymer to be blended with the tackifier polymeric additive. In other embodiments, the general HSP's of typical acrylic adhesive polymers can be selected such that δD2＝15.2，δP25.4, and δH2＝4.2。
For purposes of calculating the polymer miscibility fraction of the tackifier polymerization additive, D is calculated using the following equation (II)p：
Wherein z isiIs the molecular weight of the i-th monomer, xiIs the mass fraction of the ith monomer, and Mn is the Mn of the tackifier polymerization additive.
The polymer HSP for tackifier polymerization additives or acrylic adhesive polymers can be calculated by linear combination of HSP's of the component monomers weighted by weight fraction using HSP data contained in, for example, Hansen, c.m.; hansen solubility parameters: user manual, 2 nd edition: 2007 (Handen Solubility Parameters: A User's Handbook), published by CRC, in Boca Raton. The polymer HSP of the polymer prepared from 82.4 wt.% EHA, 16.6 wt.% MMA and 1 wt.% AA was delta eachD＝15.0，δP5.0, and δH＝3.8(J/cm3)1/2Derived from the following monomeric HSPs:
3 1/2examples of monomeric HSP's in Table I- (J/cm)
Monomer
δD
δP
δH
2-ethylhexyl acrylate (EHA)
14.8
4.7
3.4
Methyl Methacrylate (MMA)
15.8
6.5
5.4
Vinyl Acetate (VA)
16
7.2
5.9
Styrene (Sty)
18.6
1
4.1
Ethyl Acrylate (EA)
15.5
7.1
5.5
Butyl Acrylate (BA)
15.6
6.2
4.9
Acrylic Acid (AA)
17.7
6.4
14.9
Acrylic acid methyl ester (MA)
15.3
6.7
9.4
Hydroxypropyl acrylate (HPA)
16
13.2
13.4
In the case where monomeric HSPs are not available, HSPs can be estimated from the relevant monomeric and radical contributing terms by the radical contribution method. According to Hansen, c.m.; hansen solubility parameters: user manual, 2 nd edition: 2007, CRC Press, the group contribution method described in Boca Raton, HSP terminology can be estimated as the sum of contributions from different groups in the monomer using the following equation (III):
where in equation (III), δ may be any of the three components of the HSP, U is the radical contribution of each different portion of the monomer of the selected component of the HSP, and V is the volume contribution of each different portion of the monomer. For example, the HSP of Sodium Vinyl Sulfonate (SVS) can be estimated from the HSP of methyl vinyl sulfone and the radical contributions from the literature. Methyl vinyl sulfone has the structure H2C＝CH-S(＝O)2Me and SVS has the structure H2C＝CH-S(＝O)2ONa; and thus, the HSP of SVS can be estimated by taking the radical contribution of methyl vinyl sulfone minus the radical contribution of methyl, plus the radical contribution of hydroxyl, and adjusting to convert hydroxyl to sodium salt. Data for methyl vinyl sulfone, methyl and hydroxyl groups are available from Hansen, c.m.; hansen solubility parameters: user manual, 2 nd edition: 2007, CRC Press, Boca Raton, and data for sodium salt adjustment are available from Barra, J.;-a.; butamante, P.Eur.J.Pharm.Sci.2000,10, 153-.
3 1/2TABLE II-estimation of HSP's of SVS (J/cm)
By way of illustration, δ of SVSHCan be calculated using the following equation (IV):
it will be apparent to one skilled in the art how to calculate HSPs for other monomers using the group contribution method described above. In addition, Hansen, c.m. can also be used for HSP; hansen solubility parameters: user manual, 2 nd edition: 2007, CRC Press, the method described in Boca Raton calculates from experimental data for the monomer in question.
For example, as calculated using equation (I) above, the polymer miscibility fraction of the tackifier polymerization additive may be >0 in one embodiment; from 0 to 3 in another embodiment, and from 0 to 1 in yet another embodiment; and in yet another embodiment may be 0.05 to 0.9. If the polymer miscibility fraction of the tackifier polymeric additive is less than 0, then it is possible that the adhesion of an adhesive formulated with the tackifier polymeric additive and an acrylic adhesive will not be greater than the adhesion of an unformulated acrylic adhesive.
In another broad embodiment, the invention comprises a tackified adhesive composition that is a blend of: (I) at least one adhesive polymer and (II) at least one of the tackifier polymer additives described above. The tackified adhesive compositions of the present invention can be distinguished from the tackified compositions disclosed in the prior art by increasing adhesion without a significant decrease in cohesion (shear resistance) of the tackified adhesive compositions of the present invention, as compared to the tackified compositions disclosed in the prior art that do not have the tackifier polymer additive of the present invention.
The adhesive polymer (component (I)) of the present invention comprises, for example, rubbers such as isoprene and acrylonitrile-butadiene-styrene, and polymers or copolymers prepared from styrene, butadiene, ethylene, vinyl acetate, acrylic acid and esters thereof, and methacrylic acid and esters thereof. In a preferred embodiment, the adhesive polymer is a pressure sensitive adhesive polymer that is a polymer or copolymer of styrene, butadiene, ethylene, vinyl acetate, acrylic acid and esters thereof, and methacrylic acid and esters thereof.
The amount of acrylic adhesive polymer (component (I)) used to make the tackified acrylic adhesive composition may be, for example, from 45 to 99 weight percent in one embodiment, from 60 to 95 weight percent in another embodiment, and from 50 to 90 weight percent in yet another embodiment.
The tackifier polymer additive of the present invention, component (II), comprises one or more of the tackifier polymer additives described above.
The amount of tackifier polymer additive (component (II)) mixed with the acrylic adhesive polymer (component (I)) to make a tackified acrylic adhesive composition may be, for example, from 1 to 55 weight percent in one embodiment, from 5 to 40 weight percent in another embodiment, and from 10 to 50 weight percent in yet another embodiment.
To make the tackified acrylic adhesive composition of the present invention, optional compounds, agents and additives may be added to the composition as component (IV). The optional component (IV) may comprise, for example, plasticizers, crosslinkers, multivalent metal ion salts, defoamers, thickeners, rheology modifiers, stabilizers, pigments, wetting agents, and mixtures thereof. In addition, other types of tackifiers may be added in addition to the tackifier polymeric additive.
Generally, the method of making the tackified acrylic adhesive composition comprises blending: (I) at least one acrylic adhesive polymer; and (II) at least one tackifier polymer additive as hereinbefore described. For this blend, any optional components may be added as desired.
The tackified acrylic adhesive compositions of the present invention have several beneficial properties and properties, including, for example, increased adhesion; no significant decrease in cohesion (shear resistance); and low surface energy adhesion enhancement, such as adhesion to materials having non-polar surfaces, such as polyethylene including HDPE (high density polyethylene), polypropylene, and other polyolefin films. In some embodiments, the low surface energy surface has a surface energy of no greater than 35 millinewtons per meter (mN/m).
Tackified acrylic adhesive compositions improve the adhesion properties (peel force) such that the peel force of the tackified composition is greater than the peel force of the non-tackified adhesive polymer or at least >90 percent (%) of the peel force of the non-tackified adhesive polymer. For example, in one embodiment, the adhesion properties (peel force) of the tackified acrylic adhesive composition may be from 90% to 1,000% relative to the peel force of the non-tackified adhesive polymer; from 100% to 500% in another embodiment, and from 120% to 500% in yet another embodiment; and in yet another embodiment from 150% to 400%. The adhesive properties of the tackified acrylic adhesive composition can be measured by Instron (Instron) according to PSTC 101 standard peel adhesion measurement method.
For example, in one embodiment, the cohesive force (shear resistance) properties of the tackified acrylic adhesive composition may be >70 hours; in another embodiment, 71 hours to >500 hours; in yet another embodiment, 78 hours to >200 hours; and in yet another embodiment, 100 hours to >200 hours. The cohesive force (shear resistance) properties of the tackified acrylic adhesive composition can be measured by PSTC 107.
The tackified acrylic adhesive compositions of the present invention may be used in a variety of applications, such as any pressure sensitive label adhesive, including paper labels, pressure sensitive tapes, overlaminate films, and the like. In a preferred embodiment, for example, tackified acrylic adhesive compositions may be used for pressure sensitive paper label applications.
Examples of the invention
The following examples are presented to further illustrate the invention in detail and should not be construed as limiting the scope of the claims. All parts and percentages are by weight unless otherwise indicated.
The various raw materials or ingredients used in the inventive examples (inv.ex.) and comparative examples (comp.ex.) are explained below:
triton XN-45S is a surfactant available from Dow Chemical Company.
The various terms and names used in the examples are explained below:
"Sty" stands for styrene.
"MAA" represents methacrylic acid.
"nDDM" represents n-dodecyl mercaptan.
"BMA" stands for n-butyl methacrylate.
"MMA" represents methyl methacrylate.
Examples 1-4 and comparative examples A-C-tackifier polymeric additives
General procedure for the preparation of emulsions
A charge consisting of 0.6g of sodium carbonate, 720 grams (g) of deionized water, 7.2g of a 22% strength solution of sodium dodecylbenzenesulfonate in water, and 13.2g of beta-methylcyclodextrin was warmed to 87 ℃ using a flask equipped with a mechanical stirrer. An emulsion was prepared from 11.2g Triton XN-45S, 13.4g of a 22% strength solution of sodium dodecylbenzenesulfonate in water, 3.3g of methacrylic acid, 250g of water, 491.8g of styrene and 107.9g of butyl methacrylate. A portion of the emulsion (43.9g) was transferred to a flask. Next, 20.1g of a 33% strength aqueous solution of sodium persulfate was poured into the flask. After initiation of polymerization and initial heat generation, 67g of dodecyl mercaptan was added to the emulsion. The emulsion was gradually dispensed into the flask over a 3.0 hour span. At the beginning, the rate of addition of the emulsion to the flask was 2.65 grams per minute (g/min) for the first 10 minutes (min). Subsequently, the rate of addition of the emulsion to the flask was increased to 5.3g/min for the remainder of the feed time (3 hours). Starting from the emulsion feed, 111.2g of a 6% strength aqueous solution of ammonium persulfate was added at a constant rate over 3.0 hours and the reaction medium was maintained at 85 ℃ to 87 ℃.
After the feed was completed and at about 80 ℃, a solution of 1.0g of erythorbic acid (erythorbic acid) with 18.1g of water and simultaneously 20.9g of a 9.4% strength solution of tert-butyl hydroperoxide were dosed into the flask over a span of 30 minutes. Resulting in a copolymer dispersion of the polymeric tackifier additive.
The emulsion compositions described in table III were prepared using the general procedure described above.
Molecular weight measurement
To measure Mn and weight average molecular weight (Mw), the tackifier polymeric additives shown in table III were prepared in Tetrahydrofuran (THF) (high performance liquid chromatography (HPLC) grade from Fisher (Fisher)) at a concentration of about 2 milligrams per gram (mg/g). The sample was allowed to equilibrate overnight on a mechanical shaker at ambient temperature (about 25 ℃). The sample solution was filtered using a 0.45 micrometer (μm) Polytetrafluoroethylene (PTFE) filter before being subjected to the SEC (size exclusion chromatography) method.
SEC separation set-up
SEC separations were performed on a liquid chromatograph consisting of an Agilent 1100 model isocratic pump, vacuum degasser, variable injection size autosampler, and Agilent 1100HPLC G1362A refractive index detector. Data were processed using Agilent ChemStation, version B.04.03 authentication with Agilent GPC-Addon, version B.01.01.
SEC separations were performed in THF (HPLC grade, from fisher) at 1 milliliter per minute (mL/min) using a SEC column set consisting of two PLgel MIXED-D columns (available from Agilent) fitted with a 1 st order fit calibration curve in pure THF with narrow fraction polystyrene standards of 580 daltons to 371,000 daltons. A 100 microliter (μ L) sample was subjected to SEC separation.
SEC separation conditions
Column: PLGel MIXED-D column (300X 7.5 millimeter (mm) Internal Diameter (ID)) plus guard (50mm X7.5 mm ID) particle size of 5 μm
Eluent: THF (HPLC grade, Fisher)
Flow rate: 1.0mL/min
Sample solvent: THF (tetrahydrofuran)
Sample concentration: about 2mg/g (0.2%)
Injection volume of sample solution: 100 μ L
Calibration: a 10-point calibration curve (1 st order fit) was constructed using narrow fraction polystyrene standards with peak molecular weights in the range of 580 daltons to 371,000 daltons in THF and concentrations of about 0.5 milligrams per milliliter (mg/mL), which was used to estimate the relative molecular weights of the samples analyzed.
And (3) detection: refractive Index (RI)
The Tg of the polymeric tackifier additives described in table III were measured using a TA instruments Differential Scanning Computer (DSC) according to the following method steps:
1. and the temperature is changed evenly at 20 ℃/min to 150 ℃.
2. Isothermal hold for 5 minutes.
3. Equilibration was maintained at-90 ℃.
4. +/-1.00 ℃ is adjusted every 40 seconds.
5. Isothermal hold for 5 minutes.
6. The temperature of the uniform change is 3.00 ℃/min to 150 ℃.
TABLE III compositions
Calculated based on the adhesive polymer HSP, deltaD2＝15.2，δP25.4, and δH2＝4.2
The additives of the comparative examples described in table III have a Tg below 0 ℃ or a miscibility (compatibility) score below 0.
Examples 5-8 and comparative examples D-F-pressure sensitive Adhesives
The polymeric tackifier additives described in table III were blended with butyl acrylate-based pressure sensitive adhesive polymers (BA-PSA) at a solids loading of 25 parts additive to 100 parts adhesive solids to prepare pressure sensitive adhesive polymers.
TABLE IV-pressure sensitive adhesive polymers and films
Examples of the invention
Composition of
Fraction of miscibility of polymers
Films made with adhesives
Comp.Ex.D
25Comp.Ex.A:100BA-PSA
-0.30
Comp.Ex.G
Comp.Ex.E
25Comp.Ex.B:100BA-PSA
0.18
Comp.Ex.H
Inv.Ex.5
25Inv.Ex.1:100BA-PSA
0.06
Inv.Ex.9
Comp.Ex.F
25Comp.Ex.C:100BA-PSA
-0.06
Comp.Ex.I
Inv.Ex.6
25Inv.Ex.2:100BA-PSA
0.21
Inv.Ex.10
Inv.Ex.7
25Inv.Ex.3:100BA-PSA
0.23
Inv.Ex.11
Inv.Ex.8
25Inv.Ex.4:100BA-PSA
0.26
Inv.Ex.12
Examples 9-12 and comparative examples G-I-films made with Adhesives
Inventive examples 5-8 and comparative examples of pressure sensitive adhesive polymers. Examples D-F adhesive films were prepared by applying a wet adhesive on silicone coated release paper and then drying the adhesive at 80 ℃ for 5 min. The dried adhesive was then transferred to 2 mil PET film for adhesive testing.
Test results
The above blends of additives with butyl acrylate adhesive polymer were tested for Pressure Sensitive Adhesive (PSA) performance (according to PSTC 101 (peel adhesion test) PSTC-16 (loop tack test) and PSTC 107 (shear force test) methods) on stainless steel substrates and high density polyethylene (HPDE) substrates. The results of the PSA test are described in table V. Ex. g was not tested due to poor compatibility (i.e., poor film clarity). Ex.i also has poor film clarity and poor results with EHA-based adhesives.
TABLE V-test results
The inventive examples provide adhesion enhancement such that the peel results of the inventive examples exceed those of adhesives without additives in the comparison without reducing shear resistance below 72 hours. Example H, shear resistance decreased to 70 hours.
Examples 13-16 and comparative example J-L-pressure sensitive Adhesives
The polymeric tackifier additive described in table III was blended with a 2-ethylhexyl acrylate-based pressure sensitive adhesive polymer at a solids loading of 25 parts additive to 100 parts adhesive solids to prepare a pressure sensitive adhesive polymer as described in table VI.
TABLE VI pressure sensitive adhesive polymers and films
Examples 17-20 and comparative examples M-O-films prepared with Adhesives
Inventive examples 13-16 and comparative pressure sensitive adhesive polymers. Examples J-L were used to prepare adhesive films by applying a wet adhesive on silicone coated release paper and then drying the adhesive at 80 ℃ for 5 min. The dried adhesive was then transferred to 2 mil PET film for adhesive testing.
The clarity of the resulting film of the blend was qualitatively assessed as an indication of the compatibility of the additive with the acrylic adhesive polymer. Film clarity was determined by visual inspection of the film. Comparative examples using films of comparative example additives with miscibility fractions below 0 have "poor" films, while inventive examples using films of inventive example additives with miscibility fractions >0 have "good" to "very good" film clarity as determined by visual observation.
The blends were then tested for PSA properties on stainless steel and HPDE substrates. The results of the PSA test are described in table VII. Comp.ex.j was not tested due to poor compatibility (i.e., poor film clarity).
TABLE VII-test results
The inventive examples provide adhesion enhancement such that the peel force of the peel produced in the inventive examples is in most cases higher than in the case of the additive-free adhesive, and in all cases > 90% additive-free adhesive without reducing the shear resistance to less than 72 hours. In contrast, the comparison produced 20 minutes of peeling. Example N is less than 90% of the adhesive without the additive.
OTHER EMBODIMENTS
The tackifier polymeric additive of the present invention comprises the emulsion polymerization reaction product of: (a) at least one monomer having a homopolymer glass transition temperature of >80 ℃ in one embodiment and from 0 ℃ to 60 ℃ in another embodiment, such as a monomer selected from the group consisting of: aromatic monomers, methyl methacrylate and mixtures thereof; (b) at least one acrylate or methacrylate monomer; and (c) at least one chain transfer agent; wherein the tackifier polymeric additive has a polymer miscibility fraction >0 in one embodiment and >0 to 3 in another embodiment (which is a general calculation of fractions not specific to a given adhesive blend).
In one embodiment, the monomer having a homopolymer glass transition temperature of >80 ℃ of the tackifier polymeric additive may be selected from the group consisting of: styrene, methyl methacrylate, alpha-methyl styrene, and mixtures thereof.
In another embodiment, the at least one chain transfer agent of the tackifier polymerization additive may be selected from the group consisting of: tert-dodecyl mercaptan; n-dodecyl mercaptan; 3-mercaptopropionic acid; 3-mercaptopropionic acid methyl ester; 3-mercaptopropionic acid butyl ester; isopropyl alcohol; isobutanol; lauryl alcohol; tert-octanol; carbon tetrachloride; tetrachloroethylene; trichlorobromoethane; and mixtures thereof.
In yet another embodiment, the glass transition temperature of the tackifier polymeric additive of the present invention may be >0 ℃; a number average molecular weight of 1,200Da to 20,000Da in one embodiment, and 1,500Da to 10,000Da in another embodiment; and the tackifier polymeric additive has a polymer miscibility fraction > 0.