Acrylic formulation

Perhaps a more specialized case of using plasticizers in acrylic formulations can be found in drug delivery patches. Here, plasticizing additives called excipients... 

The addition of hydrogenated castor oil to a copolymer of acrylamide and sodium acrylate formulation will suspend the copolymer and retard the settling process [1657]. 

Any change in rheology brought about by addition of a biocide will be unacceptable unless the formulation can be so designed to take such an effect into account However, serious changes in viscosity which may occur, especially with some acrylic formulations, will render a biocide unusable. 

As the light intensity was increased above 100 mW cm-2, the value of (Rp)max was hardly changed, as shown in Figure 5. A similar behavior was observed with the vinyl ether-based formulation, (Rp)max levelling off at about the same value (20 mol l"1 s"1) as for the acrylate formulation (18 moll-1 s-1). Such a rate saturation effect, which has been found in nearly all of the formulations studied, is difficult to explain. It is not due to a time resolution limitation of the RTIR technique, as shown... 

Hermansson et al. carried out extensive investigations on the fire-retardant behavior of ethylene-acrylate copolymer modified with chalk and silicone elastomer.30 32 They have shown that incorporation of a silicone elastomer (at 5wt.%) and chalk filler (at 30wt.%) can greatly improve the flame-retardant properties of ethylene butyl acrylate formulations. The results show that, compared to the pure polymer, an increase in the LOI from 18 to 30, and a decrease in the peak heat release rate (PHRR) from 1300 to 330kW/m2 were observed. 

The melt-dripping behavior of various ethylene-acrylate formulations with chalk and silicone have also been addressed by exposing these formulations to a Bunsen burner. It has been demonstrated that viscosity plays a crucial role in this process by affecting the transport of volatile gases, eventual dripping, and the formation of the intumescent structure.32... 

Table 20. Photoinitiation activity, expressed as % conversion, of polymer-bound BAE systems and BIBE in the UV curing of various acrylic formulations [108]...

Comonomers mixture 73.4% of triethylene glycol (TEGDA) and 26.6% of UVE74 (Setacure AP570). Belt speed 8 m/min. Photoinitiator concentration 0.1 moll" in terms of photoreactive groups. Thickness of liquid film SOpm Number of passes under UV lamps required to cure the acrylic formulation Determined by H NMR analysis... 

One way of minimizing the detrimental effect caused by chain transfer on decreasing molecular weight and crosslink density of UV curable coatings has been successfully applied [115] by using copolymerizable methacrylic monomers containing the tertiary amine moiety as components of reactive acrylic formulations in the presence of benzoin ether derivatives. 

The comparison of the kinetic data reported in Tables 26 and 28 clearly shows that poly(VBPO-co-MMA)s are more active in the photoinitiated polymerization of the HDDA/BA equimolar mixture than poly(MAPO-co-MMA)s, notwithstanding their uncomplete solubility in the acrylic formulation. In particular, the remarkable shortening of the induction period (to) causes a sharp increase of the overall polymerization efficiency in poly(VBPO-co-MMA)s, as indicated by ti/2 values which are about one third of those for poly(MAK)-co-MMA)s. 

In order to obtain complete solubility of poly(VBPO) and poly(VBPO-co-MMA)s in the HDDA/BA equimolar mixture, UV curing experiments have also been repeated on the same acrylic formulation diluted with chloroform and the results compared with those found for the corresponding low-molecular-weight structural model compound 4-isopropyl-benzoyldiphenylphosphinoxide (IBPO). 

Another interesting procedure for obtaining a two-layer system involves [97] the formation of a base layer of the polymeric photoinitiator, through a spin coated film onto different substrates, followed by their immersion, under UV irradiation, into multifunctional acrylic formulations dissolved in solvents unable to remove the base layer from the substrate. By this method, a top layer of crosslinked acrylic resin is obtained, having strong adhesion to the substrate. The replacement of the polymeric photoinitiator by a low-molecular-weight analogue... 

Table 31. UV curing activity, as determined by Koenig pendulum hardness, of a Ti02-pigmented polyester acrylate formulation in the presence of polymeric and low-molecular-weight initiators based on thioxanthone and hydroxypropiophenone moieties, as a taction of irradiation conditions ...

Figure 22. Visible-light polymerization of acrylic formulation with DBIF and tetramethylammo-nium tetraorganoborates as electron donors. Data from Ref, [89].

Peroxides, which are used as curing agents for methacrylates, are oxidative in nature. These should not be subjected to high temperatures, fire or acids. Certain biocides used in acrylic formulations are toxic in nature. Such products should not be allowed to make contact with skin or eyes. In the event of such contact, thorough washing should be made with clean water. 

The phenomenon of creep in grouted soil masses has been recognized since the late 1950s (the earliest studies were made by the author with acrylamide grouts in 1957. Results were published shortly afterward in an inter-company report, and are shown in the section on acrylic formulations). 

Within the acrylate formulations we were especially interested in the effects of acrylonitrile-butadiene rubber modification of photopolymers with varying multifunctional monomers, photoinitiator concentration and light intensity. 

FIGURE 10.10 Plot of the relative efficiency observed for the polymerization of an epoxy acrylate formulation in the presence of various photoinitiators as a function of their dissociation quantum yields. See the formulas of DMPA, BME, HCAP, HAP, TMPK, MPK, MPPK and TPO in Table 1. 

Figure 5. Effect of dose rate on polymerization temperature of Ludopal U150-butyl acrylate formulation.

Ludopal-Butyl Acrylate Formulation. The Ludopal U150 resin is recommended for wood varnishes. It forms films with elasticity and surface hardness. It contains 34% styrene the butyl acrylate-styrene-polyester ratio is 20 27 53, and the formulation viscosity is 150 mPa s at 25 °C. 

In a second study we have compared the performance of three commercial photolnltlators for surface cure in a commercial urethane acrylate formulation. The following photoinitiators were utilized in this study HCPK - alpha-hydroxy-alpha-cyclohexylphenylketone (Structure II), BDMK - benzil-dimethyl-ketal (Structure III), and AAP (Structure IV). The extinction spectra of these initiators are in Figure 8. 

Table IV shows curing results for a commercial urethane-acrylate formulation cured under the conditions of Figure 9 (0.5 mil thickness coating containing 3% photolnitlator).

Demonstration of Dual Cure. To demonstrate thermal cure after UV cure three sets of films were prepared for Dynamic Mechanical Analysis (DMA). In the first set, four formulations were based on AM 1, AH 2, the epoxy acrylate, amd the urethane acrylate. Formulations used the test resin at 65% in TPGDA, and included 3% Darocur 1173 as a source of free radicals. DMA plots for the epoxy acrylate and urethane acrylate are shown in Figure 9. The elastic or storage modulus (E ) in the rubbery region is often used as a measure of crosslink density. The maximum of the tan delta plot, not shown, is... 

One difference with acrylic adhesives is the fact that they do often contain large amounts of highly reactive substances (monomers) that are used to achieve some of the unique properties associated with this family of products. In some cases, certain monomers may have a tendency to autopolymerize (cure without the use of externally added accelerators or hardeners). Consequently, shelf stability with some systems ean be a problem at relatively low temperatures. Even at as low as 44°C some acrylic formulations will begin to cure and harden in as little as a few weeks if maintained at these temperatures. Large containers [above 5 gallons (ca. 19 L)] can worsen this problem. 

The laminate sheet is a flexible decorative sheet for use in surfacing an automobile body panel. The laminate revealed in this invention contains several layers, including clearcoat, tie coat, color coat, and adhesive layer. Clearcoat is formulated from polyvinylidene fluoride (to assure excellent weather resistance), tie coat is formulated from acrylic (good adhesion to both clear coat and color coat and weather resistance), color coat was formulated from PVC (see formulation in the above table) and adhesive was pressure sensitive acrylic formulation. 

In Figure 5 the UV-Vis spectra of a radical photoinitiator and the BaTiOs (BT) filler that was used in an acrylic formulation are presented. It is evident that there is a competitive absorption between the photo-initiator and the ceramic powder in the UV region between 200 and 400 nm. That leads to a linear decrease of acrylic double bond during UV irradiation by increasing the filler content in the photocurable formulation [Lombardi et al, 2011],... 

One property common to UV-cure.d acrylate formulations as was discussed earlier is relatively poor surface-cure due to oxygen inhibition (see Fig. 1). This effect is most predominant at low photoinitiator concentrations, in thin coatings. Adhesive formulations can benefit from this property by enhancing surface tack via the presence of residual uncured resin. Post-cure, from residual cross-linking, or other anaerobic chemistry, can later result in enhanced bond strength. 

The cured properties of UV-aerobic acrylics include high tensile strengths, heat resistance, impact strength, and other properties expected of aerobic acrylics. Formulations have been developed with properties ranging from hard, tough adhesives with a Shore-D hardness of 80 to soft, elastomeric materials with a Shore-A of 10, similar to silicone rubber. 

---