EP2917270A2

EP2917270A2 - Particle foams with corrosion-inhibiting additive

Info

Publication number: EP2917270A2
Application number: EP13783600.3A
Authority: EP
Inventors: Dietrich Scherzer; Klaus Hahn; Anita KRÖNER; Joachim Ruch
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2012-11-05
Filing date: 2013-10-29
Publication date: 2015-09-16
Also published as: WO2014067948A2; WO2014067948A3; TW201431918A

Abstract

The invention relates to a particle foam which contains 0.5 to 8 wt.-% of one or more corrosion inhibitors, selected from among amines, triazoles, carboxylic acid esters, carboxylic acid salts, nitrites, alcohols or mixtures thereof, to methods for producing said foam and to the use for packaging corrodible metal articles.

Description

The present invention relates to a particle foam containing corrosion inhibitors, as well as methods for its production and use for packaging of corrosive metal objects.

To prevent corrosion during transport or storage of metal parts, they may be oiled or greased beforehand. The oil or grease, however, must be removed before use. For this purpose, organic solvents are usually required.

The subsequent removal of the oil or grease can be avoided by the use of Volatile Corrosion Inhibitor (VCI) components. For this purpose, a VCI active substance mixture can be introduced into the packaging. However, the corrosion inhibitors are difficult to handle because of their properties.

EP 2 184 162 A1 describes a packaging material for articles susceptible to corrosion of metal. The outer side of the packaging is formed by a plastic film, for example a thin polypropylene film, which is coated with an adhesive layer, for example a 1-pack

Polyurethane adhesive, is connected to a plastic fleece. In the adhesive layer, a small amount of a VCI active substance was introduced, which ensures a rapid build-up of complete protection against corrosion via the gas phase and also a long-term protection. US 2009/01 1 1901 describes an open or closed cell foam structure, preferably of a polyolefin, in which an effective amount of a volatile corrosion inhibitor is incorporated in the polymer and released by controlled migration on the surface of the foam. The object of the present invention was to provide an elastic packaging material with corrosion-inhibiting equipment as well as processes for its production, which ensures a sufficient corrosion protection effect over a longer period of time.

The object has been achieved by a particle foam which contains 0.5 to 8% by weight of one or more corrosion inhibitors selected from amines, triazoles, carboxylic acid esters, carboxylic acid salts, nitrites, alcohols or mixtures thereof.

The particle foam contains in total preferably 0.5 to 8 wt .-%, particularly preferably 1 to 6 wt .-% of the preferably volatile corrosion inhibitors. Suitable corrosion inhibitors are the commercially available VC I active substances (volatile corrosion inhibitor), for example nitrite compounds, amines, ammonium salts or carboxylic acid salts. Table 1 shows suitable substances which, individually or in combination, are effective as corrosion inhibitors for metals.

Table"! :

Triazoles such as benzotriazole, 2-mercaptobenzotriazole, methylbenzotriazole and derivatives, aminobenzotriazoles, 4-amino-5-mercaptopropyl-triazole

Guanidines, alkylguanidines or their salts

Immidazoles, such as benzimidazole, 2-benzimidazole-thiol,

Higher amines, such as dodecylamines, tridodeclamine, polyamines, ethylenediamine, diaminohexane and their salts,

Stannic acid, its esters and salts

alkanolamines

urea compounds

Quaternary ammonium salts, such as ammonium lactates, ammonium formate, ammonium acetate, ammonium oxalate, ammonium benzoate, diammonium citrate,

Ammonium hydrogentartrate, ammonium dihydrogen citrate, ammonium nitrate,

Ammonium Phosphate, Ammonium Dihydrogen Phosphate, Ammonium Amidosulphate, Ammonium Sulfate, Diammonium Hydrogen Phosphates, Ammonium Hydrogen Sulfates, Ammonium Sulfite, Ammonium Tartrate, Ammonium Succinate, Ammonium Adipate, Diammonium Ethylenediaminetetraacetate, Ammonium Borate,

Ammonium salicylate

Thiazoles, such as 6-methoxy-aminobenzothiazole,

Nitrites, such as sodium nitrite, ammonium nitrite, nitrite esters and organic nitro compounds

Carboxylic acids and their salts, such as sodium benzoate, sodium salicylate, sodium macropate, nitrobenzoates

Benzotriazole, sodium nitrite, sodium benzoate or mixtures thereof are particularly preferably used as corrosion inhibitors. The density of the particle foam is generally in the range of 10 to 100 kg / m ³ .

The particle foam according to the invention is formed by thermoplastic foam particles, preferably foam particles of prefoamed, expandable styrene polymers, in particular expandable polystyrene (EPS), prefoamed expandable polystyrene / polyethylene mixtures or expanded polyolefins. Particular preference is given to using elastic particle foams made from expandable polystyrene / polyethylene mixtures, as described, for example, in WO 2004/085527, WO 2004/085528 or WO 2009/1 12549. Preferred foam particles P are obtained by prefoaming expandable, thermoplastic polymer particles which

A) 45 to 97.9 wt .-%, preferably 55 to 78.1 weight percent of a styrene polymer, B1) 1 to 45 wt .-%, preferably 7 to 15 weight percent, of a polyolefin with a

Melting point in the range of 105 to 140 ° C,

B2) 0 to 25 wt .-%, preferably 5 to 10 weight percent, of a polyolefin with a

Melting point below 105 ° C,

C1) 0.1 to 25 wt .-%, preferably 6 to 15 weight percent, of a styrene-butadiene or

Styrene-isoprene block copolymers,

C2) 0.0 to 10 wt .-%, preferably 0.8 to 3 weight percent, of a styrene-ethylene-butylene

block copolymers,

D) 1 to 15% by weight, preferably 3 to 10% by weight, of a propellant,

E) 0 to 5 wt .-%, preferably 0.3 to 2 weight percent, of a nucleating agent, wherein the sum of A) to E) 100 wt .-% results.

Particularly preferably, the expandable thermoplastic polymer particles, from which the foam particles P are obtained by prefoaming, consist of the components A) to E). In the foam particles, the blowing agent (component D) has essentially escaped during the pre-foaming.

The expandable thermoplastic polymer particles contain 45 to 97.9 wt .-%, preferably 55 to 78.1 wt .-% of a styrene polymer A), such as standard (GPPS) - or impact polystyrene (HIPS) or styrene-acrylonitrile copolymers (SAN ) or acrylonitrile-butadiene-styrene copolymers (ABS) or mixtures thereof. The expandable, thermoplastic polymer particles used to produce the foam particles P1 preferably contain styrene polymer A) as standard polystyrene (GPPS). Particularly preferred are standard polystyrene types having weight average molecular weights in the range of 120,000 to 300,000 g / mol, in particular 190,000 to 280,000 g / mol, determined by gel permeation chromatography; and a melt volume rate MVR (200 ° C / 5 kg) according to ISO 1 13 used in the range of 1 to 10 cm ^3/10 min, for example PS 158 K, 168 N or 148 G of BASF SE. To improve the fusion of the foam particles during processing to the molded part, easily flowing types, for example Empera® 156L (Innovene), can be added

As further components B), the expandable thermoplastic polymer particles comprise polyolefins B1) having a melting point in the range from 105 to 140 ° C. and polyolefins B2) having a melting point below 105 ° C. The melting point is the melting peak determined by DSC (Dynamic Scanning Calorimetry) at a heating rate of 10 ° C./minute.

The expandable, thermoplastic polymer particles contain 1 to 45 weight percent, in particular 7 to 15 wt .-% of a polyolefin B1). The polyolefin B1) used is preferably a homo- or copolymer of ethylene and / or propylene having a density in the range from 0.91 to 0.98 g / l (determined according to ASTM D792), in particular polyethylene. As a polypropylene In particular injection molding grades come into consideration. Suitable polyethylenes are commercially available homopolymers of ethylene, such as PE-LD (injection molding types), LLD, -HD, or copolymers of ethylene and propylene (for example Moplen® RP220 and Moplen® RP320 from Basell or Verify®). Dow types), ethylene and vinyl acetate (EVA), ethylene acrylates (EA) or ethylene-butylene acrylates (EBA). The melt volume index MVI (190 ° C / 2.16 kg) of the polyethylenes is usually in the range of 0.5 to 40 g / 10 min, the density in the range of 0.91 to 0.95 g / cm ³ . In addition, blends with polyisobutene (PIB) (eg Oppanol® B150 from BASF Aktengesellschaft) can be used. Particularly preferred is LLDPE having a melting point in the range of 1 10 to 125 ° C and a density in the range of 0.92 to 0.94 g / L used.

Also suitable as component B1) are olefin block copolymers which are composed of a polyolefin block PB1 (hard block) and a polyolefin block PB2 (soft block), as described, for example, in WO 2006/099631. The polyolefin block PB1 preferably consists of 95 to 100% by weight of ethylene. The PB2 block is preferably composed of ethylene and α-olefin, where as α-olefins styrene, propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, norbornene, 1-decene, 1, 5-hexadiene or mixtures thereof. Preferred as PB2 block is an ethylene-α-olefin copolymer block with 5 to 60 wt .-% α-olefin, in particular an ethylene-octene copolymer block. Preference is given to multiblock copolymers of the formula (PB 1 -PB 2) n, where n is an integer from 1 to 100. The blocks PB1 and PB2 essentially form a linear chain and are preferably distributed alternately or statistically. The proportion of the PB2 blocks is preferably 40 to 60% by weight, based on the olefin block copolymer. Particularly preferred are olefin block copolymers with alternating, hard PB1 blocks and soft, elastomeric PB2 blocks, which are commercially available under the name INFUSE®.

With a lower proportion of polyolefin B1), the blowing agent retention capacity increases significantly. Thus, the shelf life and the processability of the expandable thermoplastic polymer particles are significantly improved. In the range from 4 to 20% by weight of polyolefin, expansible thermoplastic polymer particles having a long storage life are obtained without the elastic properties of the particle foam produced therefrom deteriorating. This manifests itself, for example, in a lower demolding residual _res in the range of 25 to 35%.

As polyolefin B2), the expandable, thermoplastic polymer particles contain 0 to 25 percent by weight, in particular 1 to 10 wt .-% of a polyolefin B2) having a melting point below 105 ° C. The polyolefin B2) preferably has a density in the range of 0.86 to 0.90 g / L (determined according to ASTM D792). For this purpose, in particular thermoplastic elastomers based on olefins (TPO) are suitable. Particular preference is given to ethylene-octene copolymers which are obtainable, for example, commercially under the name Engage® 841 1 from the company Dow. Expandable, thermoplastic polymer particles containing the component B2) show a significant improvement in the bending work and tear resistance after processing into foam moldings. For specific adjustment of the desired morphology, compatibilizers (components C) are used according to the invention. A further improvement in compatibility is achieved by using a mixture of styrene-butadiene or styrene-isoprene block copolymers as component C1) and styrene-ethylene-butylene block copolymers (SEBS) as component C2).

The expandable thermoplastic polymer particles contain as component C1) 0.1 to 25 percent by weight, in particular 6 to 15 wt .-% of a styrene-butadiene or styrene-isoprene block copolymers.

For example, styrene-butadiene or styrene-isoprene block copolymers are suitable for this purpose. The total diene content is preferably in the range from 20 to 60% by weight, particularly preferably in the range from 30 to 50% by weight, the total styrene content is correspondingly preferably in the range from 40 to 80% by weight, particularly preferably in the region of 50 to 70% by weight.

Preferred compatibilizers are styrene-butadiene-styrene (SBS) triblock copolymers having a butadiene content of from 20 to 60% by weight, preferably from 30 to 50% by weight, which may be partially hydrogenated or unhydrogenated. These are for example under the name Styroflex® 2G66, Styrolux® 3G55, Styroclear® GH62, Kraton® D 1 101, Kraton® D 1 155, Tuftec® H1043 or Europren® SOL T6414 commercially. These are SBS block copolymers with sharp transitions between B and S blocks.

As component C2), the expandable, thermoplastic polymer particles contain 0 to 10 percent by weight, in particular 0.8 to 3 percent by weight, of a styrene-ethylene-butylene block copolymer (SEBS). Suitable styrene-ethylene-butylene block copolymers (SEBS) are, for example, those obtainable by hydrogenation of the olefinic double bonds of the block copolymers C1). Suitable styrene-ethylene-butylene block copolymers are, for example, the commercially available Kraton® G types, in particular Kraton® G 1650. Further, the multiphase polymer mixture may contain additives, nucleating agents, plasticizers, halogen-containing or halogen-free flame retardants, soluble and insoluble inorganic and / or organic compounds Dyes and pigments, fillers or Cotreibmittel be added in amounts that do not affect the domain formation and resulting foam structure.

As component E), the expandable, thermoplastic polymer particles contain 0 to 5 percent by weight, preferably 0.3 to 2 percent by weight of a nucleating agent or nucleating agent, for example talc. As blowing agent (component D), the expandable, thermoplastic polymer particles contain 1 to 15 percent by weight, preferably 3 to 10 percent by weight, based on the sum of all components A) to E) of a physical blowing agent. The propellants can at Room temperature (20 to 30 ° C) and atmospheric pressure gaseous or liquid. They should have a boiling point below the softening temperature of the polymer blend, usually in the range of -40 to 80 ° C, preferably in the range of -10 to 40 ° C. Suitable blowing agents are, for example, halogenated or halogen-free aliphatic hydrocarbons, alcohols, ketones or ethers. Suitable aliphatic blowing agents are, for example, aliphatic C3 to C5 hydrocarbons, such as n-propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, neopentane, cycloaliphatic hydrocarbons, such as cyclobutane and cyclopentane, halogenated hydrocarbons, such as methyl chloride, ethyl chloride, methylene chloride, trichlorofluoromethane, dichlorofluoromethane, dichlorodifluoromethane, chlorodifluoromethane, dichlorotetrafluoroethane and mixtures thereof. The halogen-free blowing agents are preferably isobutane, n-butane, isopentane, n-pentane, neopentane, cyclopentane and mixtures thereof.

Suitable co-blowing agents are those having a lower selectivity of solubility for the domain-forming phase, for example gases such as CO 2, N 2, fluorohydrocarbons or noble gases. These are preferably used in amounts of 0 to 10 wt .-%, based on the expandable thermoplastic polymer particles.

To improve processability, the final expandable thermoplastic polymer particles may be coated by glycerol esters, antistatic agents or anticaking agents.

Preferably, the resulting round or oval particles are foamed to a diameter in the range of 0.2 to 10 mm. Their bulk density is preferably in the range of 10 to 100 kg / m ³ . The expandable, thermoplastic polymer particles can be prefoamed by means of hot air or steam to foam particles having a density in the range of 10 to 100 kg / m ³ , preferably in the range of 15 to 80 kg / m ³ and then welded in a closed mold into foam moldings. The foam particles P may also contain additives, nucleating agents, plasticizers, Halogenhalti- ge or halogen-free flame retardants, soluble and insoluble inorganic and / or organic dyes and pigments or fillers in conventional amounts.

The particle foam according to the invention can be prepared, for example, by reacting expandable styrene polymers or expandable polystyrene / polyethylene

Mixtures coated with one or more, preferably volatile, corrosion inhibitors, prefoamed foam particles and sintered in a molding machine.

Alternatively, prefoamed, expandable styrene polymers, prefoamed expandable polystyrene / polyethylene mixtures or expanded polyolefins can be coated during or after prefoaming with one or more, preferably volatile, corrosion inhibitors. A further possibility consists in homogeneously mixing the, preferably volatile, corrosion inhibitors with the molten polymers during the preparation of the expandable styrene polymerates, of the expandable polystyrene / polyethylene mixtures or of the expanded polyolefins.

The particle foam according to the invention can be used for the packaging of corrosive metal objects. It is particularly suitable for the packaging of high-priced goods, for example engine parts, for overseas shipments, for in-house transport or for the storage of spare parts.

Examples of starting materials:

Expandable PS / PE granules:

Expandable polystyrene / polyethylene blends (PS / PE), obtainable according to Example 2 of WO 2009/1 12549, were used for the following examples.

Corrosion inhibitor mixture:

20% by weight of benzotriazole, 30% by weight of sodium nitrite and 50% by weight of sodium benzoate

Production of packaging moldings:

The propellant-containing PS / PE granules were prefoamed in a commercially available EPS-Druckvorschäumer (Kurtz) to foam beads. The foam beads were processed after 24 hours storage in a molding machine to block-shaped packaging molded parts (container). The density of the packaging moldings was about 20 kg / m ³ .

Corrosion test:

Standard steel plates were placed in two-part packaging moldings and sealed with adhesive tape. This was followed by a 35-day storage in the climate change cabinet (6 hours 25 ° C / 98% relative humidity, 6 hours 55 ° C / 95% relative humidity, VW / Audi test standard).

Pre-expanded, PS / PE granules were used as comparative experiments, in which no corrosion inhibitor was incorporated or applied as a coating. Example 1 (compounding of the corrosion inhibitor mixture)

3 wt .-% (Example 1 a) and 6 wt .-% (Example 1 b), based on the foam bead, a mixture consisting of 20 wt .-% benzotriazole, 30 wt .-% sodium nitrite and 50 wt .-% Sodium benzoate was incorporated into the polymer matrix during the preparation of the expandable PS / PE granules. From the material thus produced, the containers described above were foamed, which were used for storing the steel plates in the climatic chamber. The containers subjected to the environmental change test were opened weekly and the steel samples were evaluated. In the assessment, the percentage area of the corroded surfaces was given in percent (Table 2).

Table 2:

Example 2 (application to non-foamed pear surface)

A mixture consisting of 20 g of benzotriazole, 30 g of sodium nitrite and 50 g of sodium benzoate was intimately mixed together with 20 g of glycerol monostearate and 30 g of glycerol tristearate in a laboratory mixer.

In a Lödige mixer system, 2% by weight (based on the pure corrosion inhibitor mixture (powder)) was applied to the expandable PS / PE granules (Example 2a). From the material thus produced, the containers described above were foamed, which were used for storing the steel plates in the climatic chamber. The containers subjected to the environmental change test were opened weekly and the steel samples were evaluated. In the assessment, the percentage area of the corroded surfaces was reported (Table 3).

In further experiments, correspondingly 4% by weight (Example 2b) and 6% by weight (Example 2c) of this mixture were applied.

The density of the foam was 20 g / l. Table 3:

Example 3 (application to the prefoamed bead surface)

A mixture consisting of 20 g of benzotriazole, 30 g of sodium nitrite and 50 g of sodium benzoate was stirred into 100 ml of water. During pre-foaming, an aqueous solution of the corrosion inhibitor was injected by means of a nozzle into the stirred pressure prefoamer (Kurtz company). The intumescent beads were coated with in each case 1% by weight (Example 3a), 3% by weight (Example 3b) and 6% by weight (Example 3c), based on the foam bead, of the pure corrosion inhibitor.

From the material thus produced, the containers described above were foamed, which were used for storing the steel plates in the climatic chamber. The containers subjected to the environmental change test were opened weekly and the steel samples were evaluated. In the assessment, the percentage area of the corroded surfaces was reported (Table 4).

The density of the foam was 20 g / l.

Table 4:

Comparative Experiment V3 Example 3a Example 3b Example 3c

Korrosionsinhib. 0 1 3 6

[Wt .-%]

7 days 0 0 0 0

14 days 10 0 0 0

21 days 60 0 0 0

28 days 90 5 0 0

35 days 90 10 5 0

Claims

claims

1 . Particulate foam containing 0.5 to 8 wt .-% of one or more corrosion inhibitors selected from amines, triazoles, carboxylic acid esters, carboxylic acid salts, nitrites, alcohols or mixtures thereof.

Particulate foam according to claim 1, characterized in that it has a density range of 10 to 100 kg / m ³ .

Particle foam according to claim 1 or 2, characterized in that it contains foam particles of prefoamed, expandable styrene polymers, prefoamed expandable polystyrene / polyethylene mixtures or expanded polyolefins.

Particulate foam according to one of claims 1 to 4, characterized in that it contains benzotriazole, sodium nitrite, sodium benzoate or mixtures thereof as a corrosion inhibitor.

Particulate foam according to one of claims 1 to 4, characterized in that it contains foam particles which are obtained by prefoaming of expandable, thermoplastic polymer particles, which

A) 45 to 97.9 wt .-%, preferably 55 to 78.1 weight percent of a styrene polymer, B1) 1 to 45 wt .-%, preferably 7 to 15 weight percent of a polyolefin with a

Melting point in the range of 105 to 140 ° C,

B2) 0 to 25 wt .-%, preferably 5 to 10 weight percent of a polyolefin with a

Melting point below 105 ° C,

C1) 0.1 to 25 wt .-%, 6 to 15 weight percent of a styrene-butadiene or styrene

Isoprene block copolymers,

C2) from 0.0 to 10% by weight, preferably from 0.8 to 3% by weight, of a styrene-ethylene oxide

Butylene block copolymer,

D) 1 to 15% by weight, preferably 3 to 10% by weight of a blowing agent,

E) 0 to 5 wt .-%, preferably 0.3 to 2 weight percent of a nucleating agent, wherein the sum of A) to E) 100 wt .-% results.

A process for producing a particle foam according to any one of claims 1 to 5, characterized in that one or more corrosion inhibitors in the preparation of the expandable styrene polymers or expandable polystyrene / polyethylene mixtures incorporated into the polymer particles, the prefoamed particles into foam particles and in a Sintered molding machines. Process for producing a particle foam according to one of claims 1 to 5, characterized in that expandable styrene polymers or expandable polystyrene / polyethylene mixtures are coated with one or more corrosion inhibitors, prefoamed into foam particles and sintered in a proportioning machine.

A process for producing a particle foam according to any one of claims 1 to 5, characterized in that prefoamed, expandable styrene polymers, prefoamed expandable polystyrene / polyethylene mixtures or expanded polyolefins are coated with one or more corrosion inhibitors.

Use of the particle foam according to one of claims 1 to 8 for the packaging of corrosive metal objects.