Polyurethane foam for use in packaging

 

(57) Abstract:

Describes porous polyurethane polymer obtained by reaction of the composition of polyetherpolyols containing from 25 to 65 wt.% polyetherpolyols, which contains an average of from 2 to 4 hydroxyl groups/molecule and have an equivalent weight of from 150 to 500: and from 35 to 75 wt.% polyetherpolyols, which contains an average of from 1 to 6 at least 50 wt.% oxyethylene hydroxyl groups/molecule and have an equivalent weight of from 600 to 3000, and a polyisocyanate which has an average isocyanate functionality of 2.3 to 3.5 and contains methylenedianiline and at least 40 wt.% polymethylenepolyphenylisocyanate, and which has an open or interconnected porous structure with a total density of from 20 to 40 kg/m2and at a thickness of 75 mm is characterized by a value equal to 75 or less for statistical voltage, greater than or equal to 2.75 kPa. The technical result is simplification. 3 S. and 6 C.p. f-crystals, 3 tables.

This invention relates to a porous polyurethane, the method of its production and to its use for packaging of fragile or brittle items. Brittle or fragile articles, which include, for example, electronic devices, fragile glass and sensitive is ractice well-known application of porous cushioning the impact of plastic packaging material, such as polystyrene or polyurethane foam, in order to envelop and support within a rigid or semi-rigid box or shell. Such techniques are described, for example, in U.S. patent N 2897641; 3190422; 3173535; 3415364 and 3750871. When the packaging material is chosen polyurethane foam, it is generally rigid or semi-rigid polyurethane foam with a density of from 8 to 15 kilograms per cubic meter. Although rigid or semi-rigid foam will act to restrict the physical movement of the packaged product, is often observed that its ability to cushion shock loads and vibration do not always meet industrial requirements.

Alternatively, in applications such as packaging can be considered elastic or semi polyurethane foam, which, according to common opinion, has the best properties in relation to the mitigation of sound and vibration. However, the characteristics of such a foam by keeping the load does not always meet the requirements of industry for packaging of fragile items. Accordingly, it would be desirable to develop polyurethane foam for use in packages, which can effectively mitigate shock and shaking the it would also be desirable to this foam showed superior fatigue strength. Foams with improved fatigue strength can be regarded as capable of re-use in packages without immediate removal of the scrap.

In addition to the above desired performance requirements, it would be good to polyurethane foam can be obtained in the process without volatile secretions in the environment of substances that rely undesirable for her, or when their small allotments. In particular, it is desirable to avoid the application of some of halogenated gas developing agents, which are considered as aggressive in terms of ozone in the Earth's atmosphere.

In order to adapt to the above requirements, the authors have developed an alternative polyurethane foam, which is particularly suitable for packing fragile or brittle items. Exposure to such products damage due to shocks or vibrations can be expressed with the help of factor G. Under "brittle" usually means products which can be damaged under the action of factor G from 20G to 40G; "fragile" means products which can be damaged when the factor G more than 40G, up to 100G. I believe that the product is more SK is as a packaging material, this foam must significantly limit your exposure to potentially harmful G-forces on the product.

In its first aspect the invention relates to a porous polyurethane polymer that has an open or connected porous structure, with a total density of from 20 to 40 kg/cm3and at a thickness of 75 mm is characterized by a value of G equal to 75 or less for static voltage, greater than or equal to 0.4 lbs/sq. inch (2.75 kPa).

In its second aspect the invention relates to a method for producing a porous polyurethane polymer that has an open or connected porous structure, with a total density of from 20 to 40 kg/cm3and at a thickness of 75 mm is characterized by a value of G equal to 75 or less for static voltage, greater than or equal to 0.4 lbs/sq. inch (2.75 kPa), and the method includes carrying out the reaction of MDI with a composition of polyether polyols in the presence of water; where:

(a) the composition of the polyether-polyols based on the total weight of parts (i) and (ii) contains:

(i) from 25 to 65 percent polyester-polyol, which contains an average of from 2 to 4 hydroxyl groups/molecule and have an equivalent weight of from 150 to 500; and

(ii) from 35 to 75 percent polyester-poly is holding oxyethylene not less than 50 weight percent;

(b) the water is present in an amount of from 1 to 8 parts by weight per 100 parts of the composition of the polyether-polyols;

(C) the polyisocyanate is present in a quantity sufficient to provide an index of the reaction of the isocyanate from 50 to 150, has an average isocyanate functionality of from 2.3 to 3.5 and contains methylenedianiline and at least 40 weight percent polymethylenepolyphenylisocyanate.

According to a third aspect of the invention proposes a method of packaging fragile products using porous, shock absorbing material, and the material used is the above polyurethane foam, which preferably receive in accordance with the above method.

The product of polyurethane foam with open pores according to this invention has an overall average density of from 20 to 40, and preferably from 25 to 35 kg/cm3. Foam with open pores provides an attractive dimensional stability, which does not always show closed cell foams, which is very desirable when such foam is intended for use in packages. The foam of the present invention may further differ in that when the thickness of the sample 75 mm it has the value of G or less static voltage greater or equal to 0.3 psi (2 kPa), and more preferably 50 or less, when the static voltage greater than or equal to 0.3 psi (2 kPa). The phrase "value of G" means that the foam has the ability enough to dampen the shock and vibration, so that the Packed product under normal circumstances would be unlikely exposed to G-forces, most of this numerical value. The higher the value of G for foam, so it is less suitable for packing fragile or brittle items. Advantageously, the foam according to the invention has the value of G from 20G up to 75G static voltage from 0.4 to 1.5 pound per square inch (from 2.75 $ 9.65 kPa), and preferably range from 20G to 50G static voltage from 0.3 to 1.5 psi (2 to 9.65 kPa). This value of G can be determined by conventional test method, including BS7539 (1992), section 2, method 1, according to which a sample of the foam of specified thickness by dropping the selected weight from a specified height. It should be noted that the observed value of G increases with decreasing thickness of the foam sample. For this reason, the value of G different foams, if you want to compare the meaning must be determined for samples with the same orientation of the mesh is to provide a blow associated with the glass transition temperature of the polyurethane polymer, while it is advantageous to have a polymer with a glass transition temperature, which is close to the operating temperature range, often the temperature range of the environment, which can be used Styrofoam. With this purpose beneficial to the foam according to the invention have a glass transition temperature in the range from -40oC to +60oC, preferably from -10oC to +55oC, and more preferably from 0oC to +50oC.

The polyurethane foam of the present invention can be obtained by reaction of a certain composition of polyether-polyols with a certain composition of polyisocyanates in the presence of a blowing agent, which contains water.

The composition of the polyether-polyols

In the calculation for the amount of weight parts present the first and second component, the composition of the polyether-polyols contains as a first component is from 25 to 65 percent polyester-polyol which has an average of 2 to 4 hydroxyl groups/molecule and an equivalent weight of from 150 to 500; and the second component is from 35 to 75 percent polyester-polyol which has an average of 2 to 6 hydroxyl groups/molecule and an equivalent weight of from 600 to 3000, and the content of oxyethylene not less than 50 weight percent is to preferably 60 weight percent. The polyester-polyol is present as the first component has a hydroxyl equivalent weight of preferably from 200, it is better to 250, preferably to 450, better than 400. Preferably, such a polyester-polyol contained on average from 2.5 to 3.6 hydroxyl groups on the molecule. The composition of the polyether polyols preferably comprises from 35 to 60 weight percent of the polyester-polyol has an equivalent weight of from 350 to 400. The polyether-polyols which conform to this specification, used in the method of the present invention to provide the desired glass transition temperature of the final polymer. Suitable polyether-polyols for use as the first component include polyhydric alcohols, which are obtained by conducting the reaction of accelerated, for example, ethylene oxide, propylene oxide, butilenica or mixtures of two or more such oxides with an active initiator containing hydrogen. Typical initiators include water, alkalophile, such as propylene glycol, glycerin, trimethylolpropane or Ethylenediamine. Typical representatives of suitable commercially available products of polyols based on polyethers include products labeled as VORANOL (VORANOL

When it is desirable to improve the properties of the polyurethane on the bearing load, it is advantageous that upon receipt of the foam was present organic polymer in the form of particles. Suitable for this purpose are organic polymers in the form of particles include polymers of the type styrene: Acrylonitrile (SAN), polyurea (PHD), the polyisocyanate-polyamine (PIPA) and styrene-butadiene (SB). Advantageous to use an organic polymer in the form of particles are present in an amount of from 0.5 to 15, preferably from 1 to 12, and more preferably from 2 to 10 parts per 100 parts by weight of the entire composition of the polyether-polyols. When the organic polymer in the form of particles is SB-polymer, it is possible with advantage to enter into the process of foaming, being optionally pre-mixed with the composition of polyhydric alcohols by aqueous latex, in which water contributes to the performance of the foam. Suitable aqueous styrene-butadiene latexes are commercially available and include latexes from Goodyear (Goodyear), designated as LPF 6733A, LPF 6758A, and products available from Enichem (Enichem), including those designated as INTEX (INTEX) 2003 and Inteinational-polyamines (PIPA), you can enter through the suspension in the polyester-polyol, which is not necessarily different from the first or second component of the polyester-polyol, and such polymer systems polyethers-polyols commercially available. Examples of suitable and preferred commercially available polymeric polyhydric alcohols SAN include those sold Jo Dow chemical company, and this includes the products, referred to as VARILUX (VORA-LUXTMtogether with designating codes HN200 - HN206, HL100 - HL400.

The pore-forming

As mentioned, the foam according to this invention receives in the presence of from 1 to 8, preferably from 2.5 to 8, and better from 3.5 to 6.5 parts of water to 100 parts of the total weight of the composition polyhydric alcohols. The water reacts with the polyisocyanate, leading to the formation of carbon dioxide, which then acts as a pore-forming, providing the ultimate example with reduced density. A pore-forming ability, provide water, may be added to the physical pore. Examples of such physical gas developing agents include fluorinated hydrocarbons and chlorpheniramine hydrocarbons, such as dichloromethan (R-123), dichloromethane (R-apenten, hexane and cyclohexane; and the captured gases, such as air, argon, nitrogen and carbon dioxide. Carbon dioxide can also be entered by thermal decomposition using exothermic effect of the reaction of the polyurethane, or, for example, using adducts of amine/carbon dioxide. In a very preferred embodiment of the present invention, the blowing agent is water.

The polyisocyanate

The polyisocyanate used to obtain a foam of the present invention, has an average isocyanate functionality of from 2.3 to 3.5, preferably from 2.5 to 3.2, and more preferably from 2.7 to 3.1, and it contains methylenedianiline and polymethylenepolyphenylisocyanate. Polymethylenepolyphenylisocyanate is present in an amount of not less than 40, preferably not less than 50, it is best not less than 55 percent, preferably 80 percent calculated on the total weight of the polyisocyanate composition. Methylenedianiline is usually a mixture of 2,4'- and 4,4'-isomers, with the advantage that such isomers were present in a weight ratio of from 98:2 to 50:50. The total amount of MDI used to obtain the polyurethane foam should be sufficient to provide an isocyanate index Tny index of the reaction, equal to 100, which corresponds to one isocyanate group at one reactive towards isocyanate hydrogen atom, which is present on the basis of water and the composition of polyols.

In addition to the above components in the foaming process does not necessarily present in other substances, including catalyst promotion /education/ urethanes, substances, stabilizing the foam, flame retardants and antistatic agents, such as STATOR (STATURETM) II, available from Jo Dow chemical company. Substances, stabilizing the foaming include silicone surfactants, for example siloxane-oxyalkylene copolymers such as the products sold under the trademark AGOSTA (TEGOSTAB) from Th. Goldschmidt, including BF-2370 and B-4900, as well as the products sold Osi, including product, denoted as L620. Suitable catalysts that can be used for promotion of education urethane groups include tertiary amines and ORGANOMETALLIC compounds, in particular compounds of tin. Examples of compounds of tertiary amines include N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine, N,N-dimethylethanolamine, bis-dimethylaminoethyl ether and vygodno, as the catalyst was present combination of amine and/or compounds of tin. If you want to give the polyurethane partial properties to slow combustion, the catalyst can use mercury-, phosphorus - or nitrogen-containing substances, which include, for example, melamine, Tris(chloroethyl)phosphonate or, preferably, halogen-free phosphorus compounds, including, for example, triethyl phosphate.

Upon receipt of the polyurethane foam according to this invention the polyisocyanate in the reaction conditions result in contact with the composition polyhydric alcohols in the presence of a blowing agent, and, optionally, an organic polymer in the form of particles. Advantageous to pre-mix composition of polyols, a blowing agent and optionally an organic polymer in the form of particles before reaction with polyisocyanate. Suitable methods of manufacture of the packaging foam, including the following description of the optional additives that can be usefully described, for example, in "Polyurethanes Handbook", Gunter Oertel, Hanser Publishers, Munich, ISBN 0-02-948920-2 (1985); "Reaction Polymers", W. Gum et al., Hanser Publishers, Munich, ISBN 3-446-1569029 (1992).

The invention is illustrated by the following primers, the properties of the foams are observed under the following testing procedures:

Density - ISO 845-88

The deformation under compression - ISO 3386.1-86

Deformation during indentation - ISO 2439.80

Ultimate tensile strength - ISO 1798-83

Elongation - ISO 1798-83

Tear resistance ASTM D 3574-86

Elasticity - ASTM D 3574-86

Air flow - ASTM D 3574-86

Residual compression - ISO 1856-80

The value of G - BS7539 (1992)

In the examples to obtain a polyurethane foam was used substances listed below:

Polyhydric alcohol A:

VORANOL CP 1000 received when initiated by glycerol polyhydric alcohol-based polyoxypropylene, with an equivalent weight of 300, available from Jo Dow chemical company.

Polyhydric alcohol (B:

VORANOL CP 1421 obtained at the initiation of a polyhydric alcohol glycerol based polyether of Polyoxypropylenediamine (70 weight%), the equivalent weight of 1670, available from Jo Dow chemical company.

Polyhydric alcohol C:

VARALUX HN201 obtained at the initiation of a polyhydric alcohol glycerol-based Polyoxypropylenediamine, with an equivalent weight of 1870, containing 21 wt.% the styrene-Acrylonitrile polymer in the form of particles, available from the 1 wt.%, content polymethylenepolyphenylisocyanate 60 wt.%, and with an average NCO-functionality equal to 2.7.

Catalyst A:

DABCO (DUBCO) 33LV, a patented catalyst based on triethylenediamine, available from Air Products.

Catalyst B:

NIAX (NIAX) A1, patented catalyst based on bis-n,n-dimethylaminoethanol ether, available from OSi Specialities, Inc.

Catalyst C:

Octoate divalent tin.

Surfactant A:

AGOSTA BF 2370, patented surface-active agent based on silica, available from Th Goldschmidt AG.

Example 1. The polyurethane foam obtained by mixing/filling device high pressure Hennecke UBT working with the release of a polyhydric alcohol 35 kg/min and flow of all components at a temperature of 20oC. the Following table. I shows the compositions used to obtain foams, and the observed physical properties of the obtained foams.

Example 2. The value of G or characteristic slow /blow/ for foams obtained in example 1, determined by test method BS 7539 (1992), section 2, method 1. Characteristics determined for samples of foam, having a thickness of 75 mm when height is about). The observed values of G are given in table. II.

In addition, the foam according to the invention it was found that if again to measure the value of G for the same sample in multiple (3) fall, then the increase is observed only for 5-10 units. These results indicate that the foams according to the invention have a low value of G in a wide range of static electricity.

For comparing the determined characteristics to a conventional flexible tiled foam with a density of 35 kg/m3capable of withstanding high loads; which are given below in the table. III. Unlike foams according to this invention, the foam in the form of a flexible plate has the value of G, which is significantly increased when observing with multiple drops. The minimum magnitude of G allows to re-use this foam plastic as a packaging material, as it still has enough ability to dampen shock and vibration in order to minimize damage to the packaged product.

The low value of G, especially at higher static voltage, which has the foam according to this invention, makes it especially suitable for spoleczno understand products with weight less than 5 kg

1. Porous polyurethane polymer obtained by reaction of the composition of polyetherpolyols containing from 25 to 65 wt.% polyetherpolyols, which contains an average of from 2 to 4 hydroxyl groups/molecule and have an equivalent weight of from 150 to 500, and from 35 to 75 wt.% polyetherpolyols, which contains an average of from 2 to 6 hydroxyl groups/molecule, not less than 50 wt.% oxyethylene and has an equivalent weight of from 600 to 3000, with a polyisocyanate which has an average isocyanate functionality of 2.3 to 3.5 and contains methylenedianiline and at least 40 wt.% polymethylenepolyphenylisocyanate, and which has an open or interconnected porous structure with a total density of from 20 to 40 kg/m3and at a thickness of 75 mm is characterized by a value of G equal to 75 or less for static voltage greater than or equal to 2.75 kPa.

2. The method of obtaining porous polyurethane polymer with an overall density of from 20 to 40 kg/m3, which comprises carrying out the reaction of MDI with a composition of polyether polyols in the presence of water, wherein the composition of polyether polyols, based on the total weight of parts (i) and (ii) contains (i) from 25 to 65% of polyetherpolyols, which contains an average of from 2 to 4 hydroxyl groups/day from 2 to 6 hydroxyl groups/molecule and have an equivalent weight of from 600 to 3000 and content oxyethylene not less than 50 wt.%; water is present in an amount of from 1 to 8 parts per 100 weight parts of the composition of politicosocial; the polyisocyanate is present in a quantity sufficient to provide an index of reaction from 50 to 150, has an average isocyanate functionality of 2.3 to 3.5 and contains methylenedianiline and at least 40 wt.% polymethylenepolyphenylisocyanate, and porous polyurethane polymer at a thickness of 75 mm is characterized by a value of G equal to 75 or less for static voltage greater than or equal to 2.75 kPa.

3. The method according to p. 2, characterized in that the polyisocyanate has an average functionality of from 2.5 to 3.1 and contains at least 50 wt.% polymethylenepolyphenylisocyanate.

4. The method according to p. 2, where the composition of the polyether polyols contain from 35 to 60 wt.% (i) that has an equivalent weight of from 350 to 400.

5. The method according to p. 4, where the composition of the polyether polyols contain from 40 to 65 wt.% (ii) that has an equivalent weight of from 1000 to 2500 and content oxyethylene not less than 60 wt.%.

6. The method according to p. 2, where the composition further comprises polyether polyols (iii) from 0.5 to 1.5 wt.% organic polymer in the form of particles calculated on the total weight of the composition.

7. The method according to p. 6, where organicheskimim or polyisocyanate/polyamino.

8. The method of packaging fragile products using porous, shock absorbing, polyurethane foam, characterized in that the use of polyurethane foam with open pores having a total density of from 20 to 40 kg/m3and at a thickness of 75 mm is characterized by a value of G equal to 75 or less for static voltage greater than or equal to 2.75 kPa obtained in accordance with the method according to p. 2.

9. The method according to p. 8, characterized in that fragile product has a mass less than 5 kg

 

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