TW201529706A - Toughening agents for epoxy systems - Google Patents

Abstract

A curable composition comprising: (a) 30 weight percent to 98 weight percent of an epoxy resin; (b) a hardener; (c) 1 weight percent to 10 weight percent of nanosilica; and (d) 1 weight percent to 10 weight percent of a core shell rubber comprising a rubber particle core and a shell layer, is disclosed.

Description

Toughening agent for epoxy resin systems Field of invention

This invention relates to epoxy resin systems that can be used in composite applications. More particularly, the invention relates to toughening agents for use in such epoxy resin systems.

Background of the invention

Various fillers have been used to toughen epoxy systems. In particular, both hard and soft nanoparticle fillers have been used. An example of a hard nanoparticle filler is nano cerium oxide. Nano cerium oxide improves fracture toughness, rigidity, and strength. However, nano-cerium oxide does not toughen epoxy resin like soft nanoparticle filler. Epoxy resins toughened with hard nanoparticle fillers do not meet the high toughness and rigidity requirements of aerospace composite applications.

Combinations of hard and soft nanoparticle fillers have also been used in epoxy applications. For example, nano cerium oxide has been used in combination with micro rubber particles. However, such systems have exhibited losses in other desirable properties, such as glass transition temperature (Tg), modulus, and strength. In addition, the resulting compositions are not destructive and fatigue (cycle to failure) performance.

Therefore, it has a balance of destructive toughness and fatigue performance, and does not compromise on other properties such as viscosity, glass transition temperature, and modulus. The epoxy system is what you want.

Summary of invention

In a broad aspect of the invention, a curable composition comprising, consisting of, or consisting essentially of: a) from 30 weight percent to 98 weight percent of an epoxy resin; a hardener c) 1% by weight to 10% by weight of nano cerium oxide; and d) 1% by weight to 10% by weight of a core shell rubber comprising a rubber particle core and a shell.

Detailed description of the preferred embodiment

The curable composition of the present invention comprises at least one epoxy resin. The epoxy resin can be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic and can be substituted. The epoxy resin may also be mono- or poly-polymeric.

The epoxy resins used in component (a) of the present invention in the embodiments disclosed herein may vary and include conventional and commercially available epoxy resins, which may also be used alone or in two or Many are used in combination. In selecting an epoxy resin for use in the compositions disclosed herein, the properties of the final product should not be considered solely, as well as the viscosity and other properties that may affect the processing of the resin composition.

Epoxy resins which are particularly suitable for those skilled in the art are epichlorohydrin and polyfunctional alcohols, phenols, cycloaliphatic carboxylic acids, aromatic amines, or amine groups. The reaction product of phenol is mainly. A few non-limiting examples include, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, resorcinol diepoxypropyl ether, and a tricyclic ring of aminophenol. Oxypropyl propyl ether. Other suitable epoxy resins well known to those skilled in the art include the reaction products of epichlorohydrin with o-cresol and, in contrast, phenol phenolic resins. Other epoxy resins include epoxy resins of divinylbenzene or divinylnaphthalene. Mixtures of two or more epoxy resins can also be used.

The epoxy resins useful in the present invention may be selected from commercially available products, for example, DER®.331, DER332, DER383, DER334, DER580, DEN431 available from The Dow Chemical Company. , DEN 438, DER 736, or DER 732 epoxy resin or Syna 21 cycloaliphatic epoxy resin available from Syqasia. As one of the present inventions, the epoxy resin component (a) may be a liquid epoxy resin such as DER383, an epoxy novolac DEN 438, a cycloaliphatic epoxide Syna 21, and a divinyl group. A mixture of aromatic hydrocarbon dioxide, divinylbenzene dioxide (DVBDO), and mixtures thereof.

In general, the epoxy resin is present in the composition in an amount ranging from 30 weight percent to 98 weight percent, based on the total weight of the composition. In various other embodiments, the epoxy resin can be present in an amount ranging from 70 to 85 weight percent.

The composition also includes an amine hardener. Examples of amine hardeners include, but are not limited to, primary and secondary polyamines and their like, anhydrides, and polyamines. Examples include aromatic amines, aliphatic amines, cycloaliphatic amines, and amidoamines. For example, polyfunctional amines may include aliphatic amine compounds such as diethylenetriamine (DEH ^TM 20, available from Dow Chemical Company (the TDCC)), triethylene tetramine (DEH ^TM 24, available from the TDCC), four ethylene pentylamine (DEH ^TM 26, available from the TDCC), and the above amines with epoxy resins, diluents, or other adducts of amine-reactive compound. Aromatic amines such as meta-phenylenediamine and diamine diphenyl hydrazine, aliphatic polyamines such as amine ethyl hydrazine Polyethylene polyamines, and aromatic polyamines such as meta-phenyldiamine, diamine diphenylphosphonium, and diethyltoluenediamine may also be used.

In general, the amine hardener is present in the composition in an amount ranging from 0.1 to 100 parts by weight of the hardener per hundred parts by weight of the epoxy resin. In various other embodiments, the amine hardener may be present in an amount ranging from 20 to 30 parts of hardener per hundred parts of epoxy resin.

The toughening agent of the composition includes nano cerium oxide particles.

In each of the embodiments, the nano cerium oxide used is a colloidal cerium oxide sol in a resin matrix having a surface-modified, spherical shape of cerium oxide nanoparticles having a diameter of 50 nm. The particles were synthesized from an aqueous sodium citrate solution and then surface modified with organodecane and matrix exchanged to produce a 40 wt% (26 vol.%) cerium oxide masterbatch in the epoxy resin. In various embodiments, the nano cerium oxide particles have an average particle size of about 20 nm, have a very narrow particle size distribution, and most of the particle diameters are generally between 5 and 35 nm. In each of the implementations, Nanopox ^® F400 was used.

In general, the nano cerium oxide is present in the composition in an amount ranging from 1 weight percent to 10 weight percent. In another embodiment, the nanometer cerium oxide is from 2.5 weight percent to 7.5 weight percent The amount of the range is present in the composition based on the total weight of the composition.

The toughening agent of the composition also includes a core-shell rubber. The core-shell rubber comprises a rubber particle core formed of a polymer comprising an elastic or rubber polymer as a main component, and a shell formed of a polymer graft-polymerized onto the core. By graft polymerizing a monomer to the core, the shell partially or completely covers the surface of the rubber particle core. In general, the rubber particle core is composed of an acrylic acid or methacrylic acid ester monomer or a diene (conjugated diene) monomer or a vinyl monomer or a decane type monomer and combinations thereof. The core-shell rubber may be selected from commercially available products such as Paraloid EXL 2650A, EXL 2655, EXL2691 A, each available from The Dow Chemical Company, or the Kane Ace® MX series, available from Kaneka Corporation, such as MX 120. MX 125, MX 130, MX 136, MX 551, or METABLEN SX-006, available from Mitsubishi Rayon.

In general, the core-shell rubber is present in the composition in an amount ranging from 1 weight percent to 10 weight percent. In another embodiment, the core-shell rubber is present in the composition in an amount ranging from 2.5 weight percent to 7.5 weight percent based on the total weight of the composition.

Alternatively, a catalyst can be added to the curable composition. Examples of catalysts that can be used include, but are not limited to, 2-methylimidazole (2MI), 2-phenylimidazole (2PI), 2-ethyl-4-methylimidazole (2E4MI), 1-benzyl 2- A mixture of phenylimidazole (1B2PZ), boric acid, triphenylphosphine (TPP), tetraphenylphosphine-tetraphenylboron (TPP-k), and the like.

The catalyst is typically present in the curable composition in an amount ranging from 0.01 weight percent to 20 weight percent based on the total weight of the curable composition. In another embodiment, the catalyst is present in an amount ranging from 0.05 weight percent to 10 weight percent, and in yet another embodiment in an amount ranging from 0.02 weight percent to 3 weight percent.

In one or more embodiments, the curable composition can also include a filler. Examples of fillers include, but are not limited to, cerium oxide, zinc oxide; aluminum oxide, titanium dioxide, aluminum trihydrate (ATH), magnesium hydroxide, and combinations thereof.

In one or more embodiments, the curable composition can comprise a solvent. Examples of the solvent may be used include, but are not limited to, methyl ethyl ketone (MEK), dimethylformamide (DMF), ethanol (EtOH), propylene glycol methyl ether (the PM), propylene glycol methyl ether acetate (DOWANOL ^TM PMA), A mixture of 1,4-butanediol diglycidyl ether and the like.

The composition can be made by a suitable method known to those skilled in the art. In one embodiment, the core-shell rubber particles are dispersed in an epoxide matrix. In various embodiments, the dispersion is carried out at room temperature. The fillers can then be blended into the epoxy resin using high speed shear mixing, or any other mixing method known to those skilled in the art. The hardener and any other desired components, such as the above optional components, are then added to the mixture. In various embodiments, the mixture is then poured into a mold and placed at room temperature for one hour and then cured at about 70 ° C for about 7 hours.

These cured products are commonly used in composite applications, Such as windmill blades, auto parts, pressure vessels, sports goods, etc.

Instance

DER ^TM 383 (DER 383) - DGEBA type liquid epoxy resin from The Dow Chemical Company.

PARALOID ^TM EXL 2619A Impact Modifier (EXL 2619A) - Core Shell Butadiene Rubber from The Dow Chemical Company

Jeffamine ^® D230 - polyetheramine hardener from Huntsman Vestamin ^® IPD-cycloaliphatic hardener from Evonik

DEH ^TM 52 (DEH 52) - Polyamine / Polyamide Hardener from Dow Chemical Company

Nanopox ^® F400: bismuth phenol-based epoxy resin reinforced with yttria, surface-modified, spherically shaped yttrium oxide nanoparticles with a diameter of 50 nm, available from Evonik

Method of making a plate

The required amount of core-shell rubber EXL 2691A was added to DER 383 and homogenized using an IKA UltraTurrax T25 homogenizer for 30 minutes. This initial mixture is kept wet for 3-5 days, which contributes to the dispersion of the rubber particles in the epoxy matrix. After the wetting step, the required amount of Nanopox ^® F400 was added and mixed for 10 minutes at an overhead stirrer at 500-700 rpm. Following this step, the resin with the filler was homogenized for another 2 hours. The mixture was then degassed at 2-5 mm Hg for 15-20 minutes. Subsequently, the desired amount of hardener component comprising Jeffamine D-230 (64 weight percent), Vestamin IPD (33 weight percent), and DEH 52 (3 weight percent) was added and manually mixed. The mixture was then degassed for 5 minutes and poured into the mold. The mixture was held in the mold at room temperature for one hour and then placed in an oven for 7 hours at 70 °C. The plate was then slowly cooled to room temperature.

Various toughening systems having Nanopox ^® F400 (yttria nanoparticle masterbatch) as a hard filler and EXL-2691A were produced as shown in Table 1 below. Load ratings (5 weight percent, 7.5 weight percent, and 10 weight percent) for three different filler loads are also considered. The weight fraction of hard and soft fillers varies for each filler loading. For example, for 5% filler loading, five different compositions of Nanopox ^® F400 and EXL-2691A are considered as mentioned in Table 1. A total of 16 panels were manufactured as above.

These properties of each example are shown in Table 2 below.

testing method

Glass transition temperature (Tg)

The glass transition temperature was measured by differential scanning calorimetry (DSC) using a Q2000 instrument from a TA instrument. Generally, a thermal scanning range from room temperature to 250 ° C and a heating rate of 10 ° C/min are used. Two heating cycles were performed, and the curve from the second cycle was used for the Tg measurement by the "recurve point intermediate" method.

Destruction toughness (K _1C )

Destructive toughness was determined by ASTM D5045 on a typical Instron or MTS equipment. The sample was cut to size using a water knife. An initial rupture was introduced using a cold knife edge at room temperature by gently tapping the Chevron score in the sample. The rupture end should be sharp to achieve the singularity of the stress field. The sample is inspected to ensure that the score is not too long, if it is too long, try The sample was not tested. The front edge was placed in a dry ice container for 30 minutes. The test was carried out at room temperature on an Instron 5566 mechanical test frame equipped with a 200 lb load cell with a fixed chuck speed of 0.02 in/min. The sample was loaded using a clamp and a locating pin. The data was recorded using the Instron Bluehill software. In many cases, five samples were analyzed.

Modulus

The modulus was determined by dynamic mechanical analysis (DMA). The DMA of these cured samples was completed using a TA instrument RSA3 DMA. The test was performed using a three-point bending structure. The sample size is typically 10-11 mm wide and 2.6-2.8 mm thick. The sample has a length of 40 mm, which is controlled by the points that are simply supported in the three-point bending fixture. Three operations were completed for each sample. The temperature changes from room temperature to 110 ° C, using compressed gas and an internal heater as a temperature regulator. The frequency is kept fixed at 1 Hz. The strain value was determined by a strain sweep experiment and the standard value was chosen to be linear where the modulus change was linear. Typically the strain value is between about 0.0015 and 0.002. ASCII data acquired by the original data and the drawing and analysis in EXCEL ^TM TA Orchestrator software controlling the instrument. The modulus was measured at 35 °C.

Viscosity

Viscosity with a Brookfield viscosity, model DVII+ Pro. Two types of cylindrical shafts are used in different applications from SC-4-15 and SC-4-21 from Brookfield. The RPM was adjusted until the torque value for each sample reached 90-98%. For viscosity measurements, only part A is considered to have various loads of such toughening agents.

Claims (6)

A curable composition comprising: a) 30% by weight to 98% by weight of an epoxy resin; b) a hardener; c) 1% by weight to 10% by weight of nano cerium oxide; and d) 1 weight The percentage to 10% by weight includes a rubber particle core and a core shell rubber. The curable composition of claim 1, wherein the core-shell rubber comprises a monofunctional group selected from the group consisting of a carboxyl group, a hydroxyl group, a carbon-carbon double bond, an anhydride group, A combination of an amine group, a guanamine group, and the like. The curable composition according to any one of claims 1 to 2, wherein the epoxy resin is selected from a diglycidyl ether of bisphenol-A, a diglycidyl propyl-F a group of ethers, and combinations thereof, etc. The composition of any one of claims 1 to 3, wherein the hardener is selected from the group consisting of an aromatic amine, an aliphatic amine, a cycloaliphatic amine, an anhydride, a guanamine, a polyamine, and the like. A group of combinations. A method for preparing a composition according to any one of claims 1 to 4, comprising the steps of: a) dispersing the core-shell rubber into the epoxy resin to form a dispersion; and b) Rice cerium oxide and a core-shell rubber are incorporated into the dispersion. A composite consisting of the composition of any one of claims 1 to 5 Manufacturing.