Redox initiation systems for acrylic adhesives.

Abstract

The curable composition includes a reactive monomer or oligomer having an acrylate functionality, an amine, and an alkyl peroxide. The alkyl peroxide is free of or substantially free of phenyl rings. The alkyl peroxide may include dilauroyl peroxide (DLP). The curable composition may also include 3,5-diethyl-1,2-dihydroxy-1-phenyl-2-propylpyridine (PDHP). The curable composition may be provided as a two-part adhesive composition, with an A-side including DLP and an acrylic monomer and a B-side including PDHP.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 62 / 964,754, filed January 23, 2020, which is incorporated herein by reference in its entirety.

[0002] FIELD OF THEINVENTION The present disclosure herein relates to an initiation system for acrylic adhesives that is free or essentially free of benzene and benzene derivative residues. [Background technology]

[0003] Conventional acrylic structural adhesives typically contain a mixture of one or more olefin reactive monomers, such as methyl methacrylate and methacrylic acid, and a redox initiation system that cures the reactive monomers. They are usually delivered in a two-part system with a primary reactive monomer on the A side and a curing agent on the B side. The initiator system typically contains at least one oxidizing agent on the B side and at least one reducing agent on the A side. The system is co-reactive at ambient conditions, upon mixing of parts A and B, to initiate a chain polymerization reaction and cure the acrylic adhesive.

[0004] In addition, fully formulated acrylic structural adhesives typically contain other additives to improve adhesion to substrate materials, environmental resistance, flexibility, heat resistance, etc. Epoxy resins impart improved heat resistance.

[0005] The most typical oxidizing agent in acrylic adhesives is benzoyl peroxide (BPO). BPO contains traces of benzene and its derivatives (toluene, xylene, or ethylbenzene) from its natural or thermal degradation. When BPO is formulated into acrylic hardeners, these harmful compounds can accumulate over time and pose environmental, health, and safety (EH&S) hazards.

[0006] Government EH&S regulations are evolving to become more stringent. One common EH&S initiative is reducing volatile organic compounds (VOCs) in chemical products. Particularly undesirable VOCs are benzene and its derivatives, such as toluene, xylene, ethylbenzene, and styrene. In some areas, all chemical products, such as adhesives and sealants, must pass strict industry standards that include the reduction or elimination of benzene and benzene derivative residues.

[0007] It is recognized that commercially available structural adhesives often contain benzene and its derivatives, both in the "wet" adhesive and after curing. Thus, there is a need to provide tough structural adhesives that are essentially or completely free of benzene and its derivatives. This need is addressed by the embodiments disclosed herein. Summary of the Invention

[0008] This Summary lists several embodiments of the subject matter of the present disclosure, and in many cases, variations and permutations of these embodiments. This Summary is merely illustrative of many different embodiments. Reference to one or more representative features of a given embodiment is similarly exemplary. Such embodiments may or may not typically include references to features; these features may be equally applicable to other embodiments of the subject matter of the present disclosure, whether or not described in this Summary. To avoid excessive repetition, this Summary does not describe or suggest all possible combinations of such features.

[0009] Thus, in some embodiments, the present disclosure provides a curable composition, which comprises a reactive monomer or oligomer, a reactive monomer or oligomer having an acrylate functional group, an amine, and an alkyl peroxide, wherein the alkyl peroxide is free or substantially free of phenyl ring.The alkyl peroxide in some aspects comprises an alkyl diacyl peroxide, optionally dilauroyl peroxide (DLP).In some embodiments, such a curable composition can further comprise 3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine (PDHP).

[0010] In some embodiments, provided herein are two-part adhesive compositions comprising an A-side comprising dilauroyl peroxide (DLP) and an acrylic monomer, and a B-side comprising 3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine (PDHP). In some aspects, the two-part adhesive composition may further comprise a stabilizer, optionally comprising Ethanox 330. In some aspects, DLP is present at about 0.5% to about 5.0% by weight, based on the total weight of the composition, and optionally DLP is present at about 1.0% to about 2.5% by weight, based on the total weight of the composition. In some embodiments, PDHP is present at about 0.01% to about 1.0% by weight, based on the total weight of the composition, and optionally PDHP is present at about 0.1% by weight, based on the total weight of the composition.

[0011] These and other objects are achieved, in whole or in part, by the subject matter of the present disclosure. Moreover, while the objects of the subject matter of the present disclosure have been set forth above, other objects and advantages of the subject matter of the present disclosure will be apparent to those skilled in the art after consideration of the following description and examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The presently disclosed subject matter will now be described more fully hereinafter, in which some, but not all, embodiments of the presently disclosed subject matter will be described. Indeed, the presently disclosed subject matter may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

[0013] I. Definition The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the subject matter of the present disclosure.

[0014] Although the following terms are believed to be well understood by those of skill in the art, the following definitions are set forth to facilitate explanation of the subject matter of the present disclosure.

[0015] Unless otherwise specified, all technical and scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art. References to technology used herein refer to technology commonly understood in the art, including variations on these technologies or equivalent technology alternatives that should be obvious to those skilled in the art. Although the following terms are believed to be well understood by those skilled in the art, the following definitions are provided to facilitate the description of the subject matter of this disclosure.

[0016] It should be understood that in describing the subject matter of this disclosure, a number of techniques and steps are disclosed, each of which has separate benefits and each of which can also be used with one or more, or in some cases, all of the other disclosed techniques.

[0017] Thus, for the sake of clarity, this description refrains from unnecessarily repeating every possible combination of the individual steps, although the specification and claims should be read with the understanding that such combinations are fully within the scope of the disclosure herein.

[0018] Following long-standing patent law convention, when used in this application, including the claims, the terms "a," "an," and "the" mean "one or more." Thus, for example, a reference to "a component" includes, for example, a plurality of such components.

[0019] Unless otherwise indicated, all numerical values ​​expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood in all instances as modified by the term "about." Accordingly, unless otherwise indicated, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the subject matter of the present disclosure.

[0020] As used herein, when referring to a value or amount of a composition, dose, sequence identity (e.g., when comparing two or more nucleotide or amino acid sequences), mass, weight, temperature, time, volume, concentration, percentage, and the like, the term "about" is meant to encompass variations in some embodiments of ±20%, in some embodiments of ±10%, in some embodiments of ±5%, in some embodiments of ±1%, in some embodiments of ±0.5%, and in some embodiments of ±0.1% from the specified amount, as appropriate for performing the disclosed methods or employing the disclosed compositions.

[0021] The term "comprising" is synonymous with "including," "containing," or "characterized by" and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. "Comprising" is a term of art used in claim language to mean that the specified elements are essential, but that other elements may be added to form a composition within the scope of the claim.

[0022] As used herein, the term "consisting of" excludes any element, step, or ingredient not specified in the claim. When the term "consisting of" appears in a clause in the body of a claim rather than immediately following the preamble, it limits only the elements recited in that clause and does not exclude other elements from the claim as a whole.

[0023] As used herein, the phrase "consisting essentially of" limits the scope of a claim to those specified materials or steps that, in addition, do not materially affect the basic and novel characteristics of the claimed subject matter.

[0024] With respect to the terms "comprising," "consisting of," and "consisting essentially of," when one of these three terms is used in this specification, the presently disclosed and claimed subject matter can include the use of either of the other two terms.

[0025] As used herein, the term "and / or," when used in the context of a list of entities, means that the entities may be present either singly or in any combination. Thus, for example, the phrase "A, B, C, and / or D" includes not only A, B, C, and D individually, but also any and all combinations and subcombinations of A, B, C, and D.

[0026] II. Redox Initiation Systems for Acrylic Adhesives The source of benzene and its derivatives in structural adhesives was identified as being primarily from the oxidizer, BPO. Furthermore, BPO is shock sensitive, and commercial suppliers often add stabilizers to BPO, and these stabilizers often contain benzene or benzene derivatives.

[0027] After abstraction of hydrogen atoms from its surroundings, decomposition of BPO produces benzoic acid and ultimately benzene, a process that occurs naturally during storage or through thermal decomposition throughout its shelf life.

[0028] [ka]

[0029] In a first embodiment of the subject matter of the present disclosure, an oxidizer for redox-initiated acrylic resins is provided, which is free of phenyl rings. Without being bound to a particular theory or mechanism of action, the lack of phenyl rings in the oxidizer results in the absence of benzene or benzene derivatives in the cured adhesive in some aspects. Furthermore, the oxidizer is less impact sensitive than BPO and does not require stabilizers, thereby eliminating another common source of benzene emissions. This provides a more EH&S compliant adhesive product.

[0030] In one embodiment of the presently disclosed subject matter, the preferred oxidizing agent comprises an alkyl diacyl peroxide, and in some aspects preferably comprises dilauroyl peroxide (DLP). DLP has been shown to undergo room temperature redox decomposition in the presence of primary and tertiary amines and secondary and tertiary amines to initiate polymerization of the acrylic resin system (A-side). In one embodiment of the presently disclosed subject matter comprising a two-part adhesive formulation, DLP may be present in the B-side of the adhesive formulation at about 5 to about 10 weight percent, preferably about 8 weight percent, based on the weight of the B-side.

[0031] In another embodiment of the subject of the present disclosure, an acrylic adhesive is provided that contains a very low content of residual benzene and benzene derivatives. This is usually understood to be less than about 300 mg / kg, more preferably less than about 30 mg / kg, and most preferably less than about 3 mg / kg. In a preferred embodiment of the subject of the present disclosure, the adhesive can be substantially free of benzene and benzene derivatives, for example, less than about 10%, less than about 5%, less than about 1%, less than about 0.5%, or less than about 0.1%, and more preferably completely free. In a further embodiment of the subject of the present disclosure, an acrylic adhesive that contains very low or no residual aldehyde content / residue is also preferred. Most preferred is a system that contains less than about 100 ppm of aldehyde content / residue.

[0032] However, when formulated with traditional amine accelerators used in acrylic adhesives, the disclosed adhesive compositions can be slow to cure. Therefore, accelerators have been introduced that are uniquely suited for use with DLP.

[0033] In a further embodiment of the presently disclosed subject matter, the cure is accelerated by the introduction of 3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine (PDHP). The introduction of a small amount of PDHP surprisingly and effectively accelerated the decomposition of DLP. PDHP is responsible for the decomposition of DLP at room temperature. The cure time can be adjusted between about 3 minutes and about 30 minutes depending on the composition of the system. In one embodiment of the presently disclosed subject matter, PDHP can be present at about 0.01% to about 1.0% by weight based on the total weight of the composition, and is typically present in the "A-side" of the two-part adhesive formulation to keep it separate from the DLP.

[0034] III. Acrylic adhesive composition In additional embodiments of the presently disclosed subject matter, the oxidizers and accelerators can be employed in acrylic adhesive compositions, which are generally known in the art and reported in the literature, and which typically include one or more free radically polymerizable monomers, at least one rubber toughener, optional fillers, colorants, and one or more rate modifiers to control the open time (the time between application of the mixed adhesive and the time when the adhesive performance is impaired due to curing progression), and an oxygen barrier, e.g., wax.

[0035] In another embodiment of the presently disclosed subject matter, the DLP and PDHP are composed of, as major components: (a) from about 10% to about 90% by weight of at least one free radically polymerizable monomer; (b) from about 0% to about 20% by weight of an adhesion promoter; (c) from about 10% to about 80% by weight of an adhesion promoter having a weight average molecular weight (M) of less than about 18,000; w ) or a number average molecular weight (M n (d) about 1% to about 15% by weight of a primary low molecular weight toughening agent having a M of greater than 18,000, preferably as high as 100,000 to 120,000. w or about 10,000 or greater M n In the adhesive composition comprising the total weight of components (a)-(d), a supplemental polymeric toughening agent (or reinforcing agent) having the formula:

[0036] (Meth)acrylic-based monomers and / or polymers derived from (meth)acrylic-based monomers are particularly useful as at least a portion of the polymerizable component. As used herein, (meth)acrylic-based monomers refer to acrylic acid, methacrylic acid, or their amides, esters, salts, or nitriles. Representative (meth)acrylic-based monomers include, but are not limited to, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, cyclohexyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, ethyl acrylate, diethylene glycol dimethacrylate, dicyclopentadienyloxyethyl methacrylate, 2-ethylhexyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, tetrahydrofuryl methacrylate, methacrylic acid, acrylic acid, acrylonitrile, methacrylonitrile, glycidyl methacrylate, cyanoacrylate, acrylamide, and methacrylamide.

[0037] In an exemplary embodiment, the first container contains about 10% to about 90% by weight of C3-C 10 The adhesive includes a two-part acrylic structural adhesive comprising at least one methacrylate selected from alkyl mono-substituted, C1-C6 alkyl di-substituted, C1-C4 alkyl tri-substituted, and C1-C4 alkyl tetra-substituted cyclohexyl methacrylate, the ring substituents being preferably at the 3, 4, and / or 5 ring positions, a linear or branched C4-C14 branched alkyl methacrylate, about 10% to about 80% by weight of a toughening agent, and an adhesion promoter, and in a second container, a bond activator, and an optional epoxy resin.

[0038] In additional embodiments of the two-part adhesive formulations disclosed herein, it may be advantageous in some aspects to "switch" the oxidizer from a traditional B-side component of the two-part adhesive to the A-side. In certain embodiments of the presently disclosed subject matter, a DLP can be contained on the "A-side" and a PDHP on the "B-side" of the adhesive.

[0039] In further embodiments of the presently disclosed subject matter, a stabilizer or antioxidant can be included with the DLP to prevent any undesired degradation of the DLP by reaction with the monomers present in the A-side. While any suitable stabilizer or antioxidant can be used, in a preferred embodiment, the stabilizer can include Ethanox 330, available from SI Group, Inc., having the following structure:

[0040] [ka]

[0041] Other stabilizers suitable for use in embodiments of the presently disclosed subject matter include, by way of example and not limitation, p-benzoquinone, Ethaphos 368, and toluhydroquinone.

[0042] The stabilizer is preferably present in the adhesive in an amount from about 0 ppm (parts per million) to about 500 ppm, and most preferably in an amount from about 125 ppm to about 250 ppm.

[0043] Thus, in some embodiments, the present disclosure provides a curable composition, which comprises a reactive monomer or oligomer, a reactive monomer or oligomer having an acrylate functional group, an amine, and an alkyl peroxide, wherein the alkyl peroxide is free or substantially free of phenyl ring.The alkyl peroxide in some aspects comprises an alkyl diacyl peroxide, optionally dilauroyl peroxide (DLP).In some embodiments, such a curable composition can further comprise 3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine (PDHP).

[0044] The DLP may be present at about 0.5% to about 5.0% by weight, based on the total weight of the composition, or at about 1.0% to about 2.5% by weight, based on the total weight of the composition. The PDHP may be present at about 0.01% to about 1.0% by weight, based on the total weight of the composition, or at about 0.1% by weight, based on the total weight of the composition.

[0045] In some embodiments, the composition may be substantially free of any phenyl-containing components. In some embodiments, the composition may be cured or curable. In some embodiments, the composition may be substantially free of benzene or benzene derivatives, for example, less than about 5%, less than about 1%, or less than about 0.5%. In some embodiments, the composition may be completely free of benzene or benzene derivatives. In some embodiments, the composition may have low or substantially free residual aldehyde content or residues, optionally, the composition has an aldehyde content or residue of less than about 100 ppm.

[0046] In some embodiments, the composition may further comprise diisopropanol toluidine and dimethylpiperazine. In some embodiments, the composition may comprise a two-part adhesive, the two-part adhesive comprising DLP and an acrylic monomer on the A-side and PDHP on the B-side. In some embodiments, the composition may further comprise a stabilizer, optionally comprising Ethanox 330.

[0047] In some embodiments, provided herein are two-part adhesive compositions comprising an A-side comprising dilauroyl peroxide (DLP) and an acrylic monomer, and a B-side comprising 3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine (PDHP). In some aspects, the two-part adhesive composition may further comprise a stabilizer, optionally comprising Ethanox 330. In some aspects, DLP is present at about 0.5% to about 5.0% by weight, based on the total weight of the composition, and optionally DLP is present at about 1.0% to about 2.5% by weight, based on the total weight of the composition. In some embodiments, PDHP is present at about 0.01% to about 1.0% by weight, based on the total weight of the composition, and optionally PDHP is present at about 0.1% by weight, based on the total weight of the composition.

[0048] In some embodiments, the two-part adhesive composition may be substantially free of any phenyl-containing components. In some embodiments, the two-part adhesive composition may be substantially free of benzene or benzene derivatives. In some embodiments, the two-part adhesive composition may be low or substantially free of residual aldehyde content or residues, optionally the composition has an aldehyde content or residues of less than about 100 ppm. In some embodiments, the two-part adhesive composition further comprises diisopropanol toluidine and dimethylpiperazine.

[0049] Working Example The following examples are included to further illustrate various embodiments of the subject matter of the present disclosure. However, those skilled in the art should, in light of this disclosure, understand that numerous changes can be made to the specific embodiments disclosed and still obtain similar or substantially the same results without departing from the spirit and scope of the subject matter of the present disclosure.

[0050] Example 1 Evaluation of two-component acrylic adhesives In this example, a two-part acrylic adhesive was made, in this case, the B-side curing agent designated E029-8 was formulated with dilauroyl peroxide (DLP), e.g., Luperox LP (Arkema Inc), rather than the benzoyl peroxide typical in such adhesives. See Table 1.

[0051] [Table 1]

[0052] The A-side designated 8006-2 contains a typical A-side acrylic structural adhesive containing acrylate monomers, HEMA phosphate, DIIPT (diisopropanol toluidine) and DMP (dimethylpiperazine), as well as additives such as tougheners, inhibitors, waxes, and fillers such as fumed silica. See Table 1.

[0053] The A-side and B-side were mixed in a volumetric ratio of 4:1 (A:B). The mixture cured, but the cure rate was very slow. In addition, there was severe air inhibition during squeeze-out (see Table 2 below).

[0054] Example 2 The surprising effect of adding PDHP Attempts were made to identify potential accelerators to make the DLP / acrylic cure proceed more quickly. After adding cobalt naphthenate solution (6% Cu, Alfa Aesar) and copper naphthenate (8% Co, The Shepherd Chemical Company) to the mixture, no effect was observed.

[0055] Next, 3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine (PDHP) was added to the A / B mixture, for example, at about 0.50% by weight, or in the range of about 0.01% to about 0.70% by weight.

[0056] [ka]

[0057] The addition of small amounts of PDHP into the adhesive mixture surprisingly accelerated the cure and achieved a homogeneous cure. It was further revealed that the cure time could be adjusted by varying the amount of PDHP added or incorporated into the mixture. Furthermore, the inclusion of various amounts of PDHP significantly reduced air blockage. See Table 2.

[0058] [Table 2]

[0059] Example 3 Adhesion evaluation In this experiment, adhesion such as lap shear and T-peel tests against aluminum were observed. The adhesive formulations provided herein provided reasonably acceptable lap shear and T-peel strengths. For this particular application, the preferred lap shear strength is about 1700-2200 psi non-adhesive failure, and the T-peel strength can be in the range of 20-38 pli non-adhesive failure. See Table 3.

[0060] [Table 3]

[0061] The system of this example showed good bonding, but the shelf life was poor due to reaction of the PDHP with other components during storage.

[0062] Example 4 Evaluation of adhesive compositions as plastic bonders The following examples demonstrate the effectiveness of the disclosed adhesive compositions in plastic bonding systems. Metal adhesion promoters such as HEMA phosphate, monoester of phthalic anhydride, and HEMA were removed. Preliminary data showed that the A-side remained flowable and bond strength to acrylonitrile butadiene styrene (ABS) was normal. See Table 4.

[0063] [Table 4]

[0064] All systems achieved strengths in excess of 150 psi, but were not optimized, confirming adhesive cure at room temperature conditions. It is worth noting that these systems were not optimized.

[0065] Example 5 Evaluation of DLP in A-side ingredients In this example, switching of DLP and PDHP between the A-side and B-side was investigated. The goal was to obtain a viable system with adequate shelf life by eliminating the complexation of PDHP with the active hydrogen-containing components in the A-side.

[0066] For the side-switching technique, a model solution of 5.5 wt% PDHP in GY1556 epoxy resin was made. Its fluidity was monitored over time. The solution was monitored over a period of three weeks and showed little detrimental interaction between the PDHP and the epoxy resin when the fluid was left at room temperature.

[0067] A model solution of 4 wt% DLP in t-MCHMA was also made. It was stored at room temperature (RT) and in a 50°C oven. The latter gelled in 24 hours, while the RT solution remained fluid over 3 weeks, but discolored slightly. Laboratory temperatures ranged from 18-21°C. Storing A-side resin in a cold room may not be practical, but cold storage can extend shelf life.

[0068] The bonded parts were initially cured at RT conditions and then post-baked at 175°C for 30 minutes to mimic e-bake. The results showed excellent T-peel performance with the two rubber additives. The effect of LP and PDHP was also investigated to understand the performance region. See Table 5.

[0069] [Table 5]

[0070] Example 6 Evaluating the stability of adhesive compositions The above examples show that by switching between conventional Luperox LP and PDHP in the A-side and B-side, the rapid and strong interactions between PDHP and H-donor components such as HEMA, HEMA phosphate, etc., can be substantially or completely avoided. However, placing LP peroxide in the resin side (A-side) is known to be problematic; natural decomposition of the peroxide can lead to polymerization of monomers and intermediates, resulting in gelation.

[0071] Without being bound to a particular theory or mechanism of action, based on this disclosure, it was concluded that the PDHP was stable on the B-side since there were no active hydrogen-containing raw materials present on this side. No adverse effects were observed from placing the PDHP on the B-side. There was concern that the DLP on the A-side might have stability issues since the peroxide would be expected to react with the acrylic monomer over time. To overcome this issue, a stabilizer, e.g., Ethanox 330, was added to the A-side and the new adhesive formulation was tested alongside a conventional BPO-containing adhesive as a control with comparable levels of DLP and BPO. The cups were placed in a 25°C incubator and monitored over time. The following observations were made: 1) after 2 weeks, the samples containing both DLP and BPO remained fluid with little / no observable color change; 2) after 3 weeks, both samples were still fluid, but the BPO-containing sample was significantly darker / browner than the DLP-containing sample, indicating some reaction / gelation of the monomers; 3) after 2 months, the BPO-containing sample was darker brown and had clearly begun to gel, while the DLP-containing fluid had only darkened slightly; and 4) after 2.5 months, the BPO-containing fluid had gelled by approximately 50%, while the DLP-containing fluid appeared unchanged from previous observations.

[0072] The conclusion was that the Luperox LP-containing system with 10 ppm Ethanox 330 was stable for several months at 25°C, but the BPO-containing system began to gel and become unusable.

[0073] It will be understood that various details of the presently disclosed subject matter may be changed without departing from the scope of the presently disclosed subject matter. Further, the foregoing description is for purposes of illustration only and not for purposes of limitation.

Claims

1. 1. A curable adhesive composition comprising: A reactive monomer or oligomer having an acrylate functionality; Amine; Alkyl peroxide; 3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine (PD HP); Diisopropanol toluidine; and A composition comprising dimethylpiperazine.

2. The composition of claim 1 , wherein the alkyl peroxide comprises an alkyl diacyl peroxide.

3. The composition of claim 1 , wherein the alkyl peroxide comprises dilauroyl peroxide (DLP).

4. The composition of any one of claims 1 to 3 which has been cured.

5. The composition of any one of claims 1 to 4, which is substantially free of benzene.

6. The composition according to any one of claims 1 to 5, which is completely free of benzene.

7. A composition according to any one of claims 1 to 6, having low or substantially no residual aldehyde content or residues.

8. 8. The composition of claim 7 having an aldehyde content or residuals of less than 100 ppm.

9. The composition of claim 3, wherein the DLP is present at 0.5% to 5.0% by weight, based on the total weight of the composition.

10. The composition of claim 9, wherein the DLP is present at 1.0% to 2.5% by weight, based on the total weight of the composition.

11. The composition of claim 1, wherein the PDHP is present at 0.01% to 1.0% by weight, based on the total weight of the composition.

12. 12. The composition of claim 11, wherein the PDHP is present at 0.1% by weight, based on the total weight of the composition.

13. 13. The composition of any one of claims 1 to 12, comprising a two-part adhesive, said two-part adhesive comprising DLP and said acrylic monomer on an A-side and said PDHP on a B-side.

14. The composition of claim 13 further comprising a stabilizer.

15. The stabilizer has the formula: 【Chemistry 1】 The composition according to claim 14, wherein

16. A two-component adhesive composition comprising: an A-side comprising dilauroyl peroxide (DLP) and an acrylic monomer; and A side B comprises 3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine (PDHP).

17. 17. The two-part adhesive composition of claim 16, further comprising a stabilizer.

18. The stabilizer has the formula: 【Chemistry 2】 The two-component adhesive composition according to claim 17 ,

19. The two-part adhesive composition of any one of claims 16 to 18, wherein the DLP is present at 0.5% to 5.0% by weight, based on the total weight of the composition.

20. The two-part adhesive composition of any one of claims 16 to 19, wherein the DLP is present at 1.0 wt% to 2.5 wt%, based on the total weight of the composition.

21. The two-part adhesive composition of any one of claims 16 to 20, wherein the PDHP is present at 0.01 wt% to 1.0 wt%, based on the total weight of the composition.

22. The two-part adhesive composition of any one of claims 16 to 21, wherein the PDHP is present at 0.1 wt%, based on the total weight of the composition.

23. The two-component adhesive composition according to any one of claims 16 to 22, which is substantially free of benzene.

24. The two-part adhesive composition of any one of claims 16 to 23, having low or substantially no residual aldehyde content or residues, optionally having an aldehyde content or residues of less than 100 ppm.

25. The two-component adhesive composition according to any one of claims 16 to 24, further comprising diisopropanol toluidine and dimethylpiperazine.

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