DE2160691A1 - Process for the production of elastic, compressed polyurethane foams - Google Patents

Description

"Process for the production of elastic, compressed polyurethane foams"

Priority: December 7, 1970, V.St.A., No. 95 954

The invention relates to a method for producing elastic, compressed polyurethane foams, which in particular have a low ball rebound resilience.

U.S. Patent 3,506,600 (incorporated herein by reference in its entirety is) describes a process for the production of elastic, compressed polyurethane foams in which a foamable polyurethane mixture after foaming within a certain period of time and in compliance with certain ambient temperatures in the partially hardened state to one

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PAD ORIGINAL

A fraction of the original foam volume is compressed and finally fully cured. Here receives a permanently compressed foam with good physical properties, which is suitable for a variety of applications, e.g. for upholstery or for damping floor coverings such as carpets.

The polyurethane foams produced by the process of ÜS-PS 3 506 600 lead, however, in those cases in which a particularly low rebound resilience is required, not producing technically satisfactory results. In addition, these foams have the use of fillers in the foamable polyurethane mixture often an insufficient load-bearing capacity.

The object of the invention was therefore to overcome the aforementioned disadvantages and create elastic polyurethane foams with low ball rebound resilience and / or high load-bearing capacity. This object is achieved by the invention solved.

The invention thus relates to a method for producing elastic, compressed polyurethane foams from foamable ones Polyurethane mixtures containing a polyol component and an isocyanate component

(a) foaming the polyurethane mixture to form a partially cured foam mass,

(b) compressing this foam mass with the application of pressure etv / a 2/3 to Ι / ΙΌ of their original volume 0 to about

'' 10 minutes after the end of the rise time, whereby the temperature

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door during the time from 0 to about 10 minutes to about?

. "is held to 205 ⁰ C ,, and
(C) complete hardening of the foam mass with removal of the

Pressure,

which is characterized in that one is used as the polyol component a mixture of a low molecular weight polyol (I) having a molecular weight of about 100 to 1500 and a high molecular weight Polyol (II) with a molecular weight of about 2000 to 10 in a weight ratio of (Ι) ί (II) of about 1: 9 to 4 J 1 used.

The polyurethane foams produced according to the invention have a falling ball rebound resilience of less than about 40 percent, compared with Y / erten of over 45 percent in conventional Way produced compressed polyurethane foams. The compressed polyurethane foams produced according to the invention are e.g. suitable for various purposes of damping or shock absorption.

The falling ball rebound resilience of polyurethane foams is determined in accordance with ASTM D 1564-64T. A steel ball with a diameter of 9.53 mm is dropped onto the foam sample from a height of 45.7 cm, the rebound height being measured. This height, expressed as a percentage based on the height of fall (45 ₅ 7 cm), is given as the falling ball rebound resilience of the foam.

The method of the invention can be carried out by the one-step process or a modified two-stage process, the so-called semi-

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BATH ORIGINAL

prepolymer processes are carried out. Under the term "Foamable polyurethane niche" are all known combinations of polyols, such as polyether polyols or polyester polyols, organic polyisocyanates, blowing agents, catalysts and. understood other common additives and processing aids, provided the foamable polyurethane mixture contains a mixture of the low molecular weight polyol (I) and the high molecular weight polyol (II). Typical, general Recipes are in US-PS 3,072,582 and CA-PS 705,938 described. *.

The method of the invention is preferably carried out in such a way that that a polyether polyol is used both for the low molecular weight polyol (I) and for the high molecular weight polyol (II). The molecular weights of the low molecular weight ' Polyol (I) and the high molecular weight polyol (H) about 150 to 1000 and about 2500 to 6000 and the molar ratio of polyol CO to polyol (II) is preferably about 1: 5 to 2: 1.

The polyether polyols preferably used, such as alkoxylated polyhydric alcohols, preferably have medium hydroxyl numbers below about 250. These alkoxylated polyvalent Alcohols are generally random or incremental Implementation of a polyfunctional alcohol as a chain

j. . . j. . -in — Segenwart e ines basic Kut ^ ivaato.tr. starter made with exnem alkylene oxide. Examples of suitable alkylene oxides are ethylene oxide, propylene oxide, butylene oxide or amylene oxide, and halogenated alkylene oxides, such as epichlorohydrin, or mixtures of the aforementioned alkylene oxides.

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Purely for the production of alkoxylated polyhydric alcohols become polyhydric alcohols with a functionality of 2 Ms 8, such as diols, triols, tetrols or higher functional alcohols, used. Examples are ethylene glycol, propylene glycol, 2,3-butylene glycol, 1,5-pentaudediol, 1,6-hexanediol, glycerine, Trimethylolpropane, triethylolpropane, pentaerythritol or carbohydrates, such as sorbitol, sucrose, glucose or methyl glucoside. Preference is given to the reaction with the alkylene oxides polyhydric alcohols with a functionality of at least 3 are used. '

Polyisocyanates suitable for the process of the invention are, for example, tolylene diisocyanate, such as the commercially available 80:20 or 65 J 35 isomer mixtures of 2,4- and 2,6-tolylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, methylene bis-4-phenyl isocyanate, 3 , 3 ^r -bitoluylene-4,4'-diisobyanate, hexamethylene diisocyanate, naphthylene-1,5-diisocyanate, polyphenylene polymethylene isocyanate or mixtures of the aforementioned isocyanates. The amount of polyisocyanate is chosen so that at least about 0.7 HOO groups per hydroxyl group are present in the reaction system. In addition to the hydroxyl groups of the polyol, the hydroxyl groups of other compounds present in the reaction system must also be taken into account. Although a stoichiometric excess of polyisocyanate can also be used, this is generally disadvantageous for reasons of cost. Preferential

approximately.
wise, no more aTsvT, 25 NCO groups, in particular about 0.9 "to 1.1 WCO groups, are used per hydroxyl group.

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The polyurethane mixture is foamed in the presence a propellant, a catalyst and preferably a small amount of a conventional surface-active additive.

The usual blowing agents, such as water or organic blowing agents, come with up to. to 7 carbon atoms, such as halogenated hydrocarbons, low molecular weight alkanes, alkenes or ethers, or mixtures of the aforementioned blowing agents. The amount of propellant can vary widely. In general, the halogenated hydrocarbons are used in an amount of about 1 to 50 parts by weight, or water ίκ in an amount of about 1.0 to 6.0 parts by weight, based in each case on 100 parts by weight of the polyol. Typical halogenated hydrocarbons include, for example, monofluorotrichloromethane, dichlorofluoromethane, Difluordiehlormethan, 1, 1,2-Tri chlorine. 1,2,2-trifluoroethane, dichlorotetrafluorathane, ethyl chloride, methylene chloride, chloroform or carbon tetrachloride. Other special propellants are methane, ethane, ethylene, propane, propylene, pentane, hexane, heptane, diethyl ether, diisopropyl ether or mixtures of the aforementioned propellants.

Suitable catalysts are e.g. tertiary amines or metal salts, especially tin (II) salts. These catalysts can be used alone or in admixture. Preferably a Amine-metal salt mixture used. The catalysts are in generally in concentrations from about 0.04 to. 1.5 percent by weight, preferably about 0.05 to 0.50 percent by weight, based in each case on the polyol component, is used. Specific Examples of tertiary amines are N-methylmorpholine, N-Hydro.Xyäthylmorpholin, Triethylenediamine, triethylamine or trimethyl

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amine. Typical metal salts are e.g. the salts of antimony, Tin or iron, such as dibutyltin dilaurate or tin (II) octoate.

Surface-active additives suitable for the process of the invention are, for example, silicone oils, soaps or siloxane-oxyalkyleto block copolymers. Various surface-active additives are described in TJS-PS 2,834,748 and "Rigid Plastic Foams", Reinhold Publishing Corp., New York (1963) 38-42. In general, up to 2 percent by weight of the surface-active additive is used per 100 parts by weight of the polyol component. The presence of the surface-active additive improves the cell structure of the polyurethane foams.

In a preferred embodiment, the method of the invention is carried out with a polyurethane mixture, the one contains ground filler such as barite, clay or calcium sulfate. It has been shown that these fillers increase the load-bearing capacity of the compressed foams produced with it can be improved without affecting the good properties be adversely affected in terms of the low ball rebound resilience. Preferably, barite, generally in an amount of about 10 to 100 parts by weight, is preferred about 20 to 80 parts by weight, each based on 100 parts by weight of the polyol component, is used.

Further additions can be made to the foamable polyurethane mixtures substitutes such as dyes, reinforcing fibers, y / calibrators, Fragrances or antioxidants.

The density of the polyurethane foam produced according to the invention

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- ο - ■.

fabrics can move widely. The process is preferably carried out in such a way that foams with a density of about 24 to 240 g / l are produced. These foams are produced when foamable polyurethane mixtures are used which, when freely foamed and cured without the application of external pressure, produce foams with a density of about 12.8 to 64.1 gA- . '

In practice, the method of the invention is preferably performed such that, the foamable polyurethane mixture in "· a suitable Reaktionsζone -., For example, by pouring it into a respective box or a box or a conveyor belt, feeds ■ Since the foaming reaction is exothermic, is No heat supply per se required, but it may be appropriate in certain cases. The start time, ie the time from mixing the starting components to the start of the foaming reaction, which is indicated by the mixture becoming creamy, is about 0.1 to 20 seconds As the reaction temperature rises, gas bubbles develop, which results in the formation of an uncured, cellular gel mass, the volume of which gradually increases.

When the development of gas bubbles ceases, the expansion of the uncured, cellular gel mass is also stopped. In Agreement with the teaching of US Pat. No. 3,506,600 must be At this point in time, some critical process conditions must be observed in order to obtain foams that were produced before actual curing have been compressed.

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The first critical parameter is the so-called. crush time. The crush time refers to the period of time - that elapses from the end of the rise time to the application of pressure. The procedure the invention is carried out with a crush time of 0 to about 10 minutes, preferably 3/4 to about 6 minutes. Although one compresses the foam mass immediately after the end of the rise time elastic, compacted Can produce polyurethane foams, it has been shown in practice that from the end of the rise time to compression at least about 6 seconds elapse.

The second critical parameter is the ambient temperature during the crush time. It has been shown that the partially cured foam must be kept at temperatures of about 7 to 205 ° C. during the crush time. In general, v / ground at a time of 0 to crush about 2.5 minutes temperatures of about 7-205 ⁰ Cf, preferably about 7 to 94 ° C, at a crush time of about 2.5 to 5 minutes, temperatures of about 7 to 94 ° 0, preferably from about 7 to 38 ° C, and at a crush time of 5 to 10 minutes a temperature of about 7 to 44 ⁰ C, applied preferably about 7 to 30 ⁰ G. Conventional devices, such as ovens or cooling systems, may be used to maintain the aforementioned temperatures.

When carrying out the process according to the invention on an industrial scale, the work is preferably carried out at room temperature, ie at temperatures of about 21 to 44 ^° C. and with a crush time of 0 to 10 minutes.

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At the end of the crush time, the partially hardened polyurethane foam mass pressed together by means of suitable gate directions, e.g. rollers or plates.

The extent of the interaction caused by the force

"·· ι -tolffi, .si.ch in far Rahman, move upd Depends on the required compression of the polyurethane foam away. Preferably, the partially cured foam composition to achieve well-compacted foams up to compressed to about 2/3 to 1/10 of the original thickness after expansion. The desired degree of cooperation pressure can be achieved by adjusting the opening width between the pressure-conveying devices.

The duration of the application of pressure and the temperature of the devices causing the compression of the foam mass and the Play environment when performing the invention. Procedure no particular role. When carrying out the procedure on an industrial scale, however, for reasons of cost the duration of the pressure injection is kept as short as possible.

After compressing the partially hardened foam mass complete curing takes place with the removal of the pressure to the polyurethane foam- '. In general, no heat supply is required to cure the polyurethane foam mass. since a complete curing already takes place at room temperature increased temperatures are used for curing.

With prolonged application of pressure and relatively small thicknesses of the polyurethane foam mass, it can happen that the

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Removal of the pressure has already resulted in an essentially complete hardening of the foam mass with regard to its handling Has. This hardening can thus take place before, at the same time as or after the pressure is removed. All of the foregoing Process variants and combinations are identified by the expression "and complete curing of the foam mass with removal of the Pressure "recorded.

After releasing the pressure and curing completely the compressed polyurethane foam may be possible that s the foam by a small isil of the difference between original thickness "and the thickness after compression expands again. However, since the polyurethane foam has been compressed, i.e., permanently, before hardening, this is Expansion always limited to a small extent.

In the case of the discontinuous procedure, the process is the Invention carried out, for example, that the foamable polyurethane mixture in an ordinary box, e.g. a box, foamed, after the crush time has elapsed while maintaining the aforementioned temperature ranges, the box removed from the partially hardened foam mass, and the foam mass condensed. Here, the foam mass is reduced to about 2/3 to 1/10 of its original using plates or rollers Compressed in volume. The pressure is then removed so that the foam mass cures completely can. The box into which the foamable polyurethane mixture is fed is preferably dimensioned so that the finished polyurethane foam in this form or after one

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Slimming process to remove the skin that is in general forms on the foam surface, can be used. on

Foam materials ...

In this way, compressed YT such as mattresses or pillows,

manufacture by a discontinuous process.

Preferably, however, in particular on an industrial scale, the process of the invention is carried out continuously. That Process can e.g. be carried out in such a way that the stock

Including the organic blowing agent, parts of the foamable polyurethane mixture are applied via a mixing chamber to a laterally limited conveyor belt. The side limits are necessary until the foam mass has sufficiently gelled to support its own weight. Depending on the transport speed, the foam mass passes through, for example, a pair of pressure rollers within the predetermined crush time. After it has passed through the pressure rollers, an oven may be connected in order to accelerate the hardening of the compressed polyurethane foam mass. Finally, after passing through the oven, the cured foam can be cut to size by means of suitable cutting devices or trimmed in the desired manner. The polyurethane foams obtained in this way can also be used directly, for example as upholstery parts such as mattresses or pillows, or for other damping purposes. As already mentioned, the polyurethane foams produced according to the invention have a low falling ball rebound resilience, which is less than about 40 percent and generally between about 20 and 38 percent by weight. If the foaming is carried out in the presence of fillers, foams with a high load-bearing capacity are obtained. The polyurethane produced according to the invention

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Foams are used in particular where foams with low rebound resilience are required. You will, e.g. Used to make particularly soft pillows, mattresses and other upholstery. You will also be of particular benefit for shock absorption, e.g. for vehicle interior linings, as bumper protection, as suitcase lining or for packaging more sensitive instruments ^ used.

The method of the invention, can be in the context of the general Inventive concept in versatile process variants through. to lead. The compressed polyurethane foam can also be used, for example, on floor coverings such as carpets, carpets or tiles, Apply by placing the foamable polyurethane mixture directly on the back of a continuously transported web of the floor covering is applied and the partially cured foam. mass is compressed. ■

The examples illustrate the invention. All parts and percentages relate to weight, unless otherwise stated. ·.

''•Example. 1

According to the recipe given, a foamable polyurethane mixture is created by mixing the individual components (elastic type).

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Component parts by weight

oxypropylated glycerine (II).

(Molecular weight 3000) '.75

oxypropylated glycerine (I)

(molecular weight 600) 25

Tolylene diisocyanate
(NCO index *) 100)

(NCO index J 100) 55

Water . , 4

surfactant additive '.. 1.5

Tin (II) octoate 0.2

Triethylenediamine 0.3

The NCO index gives the ratio of isocyanate: hydroxyl groups in percent. ·

** ^ Silicone Surfactant DC-190 (Manuf. Dow. Corning).

The polyurethane mixture comes in an open square box with a side length of 20.3 cm "and a height of 10.2 cm foamed. 'When on the surface of the foam mass Bubbles appear, which indicate the end of the rise time, a crush time of 90 seconds is allowed at ambient temperature of 24 ° G elapse. Then the foam mass is taken out of the box and placed between plates or a press compressed into an opening of about 2.3 cm. The foam block obtained has after complete curing at room temperature a thickness of about 2.5 cm and a ball drop rebound resilience (according to ASTM D 1564-64T) of 25 percent. In the table are other properties of this polyurethane foam compiled.

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- 15 B e. i, s ρ i e.-l 2

Example 1 is repeated, but instead of the polyol ratio ' (II: I) of 75 ί 2-5 a polyol ratio of 80:20 used. The foam obtained has a falling ball rebound resilience of 38 percent. The properties are summarized in the table.

Comparative example '

Example 1 is made using 100 parts of the oxypropylated Glycerine (II) with a molecular weight of 3000 is used instead of the polyol mixture. The compressed foam has a ball-drop rebound resilience of 51 percent. This illustrates the effect that mit.der invention Use of a polyol mixture with regard to rebound resilience is reached. The results are compiled in the table. · "

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Example of origin. after meeting

He.

• borrowed

to press

Tabel

Density, when free

Foaming

(ff / liter)

■ Rebound compression density after elastic compression ity did «(s / li

iter)

1 10.2

2. 10.2 ■ Comparison 10.2

2.5 2.5 2.5

25.6 25.6

25.6

99.3 99.0 99.5

25th 0.224 38- 0.329 51 0.238

approx. values

' The compressibility indicates the pressure that is required to produce the foam

Compress 25 percent of its thickness and is a measure. for the load bearing

of the foam.

Example 3

Example 1 is repeated, but the polyol component a mixture of 60 parts of the oxypropylated glycerine (H) with a molecular weight of 3000 and 40 parts of an oxypropylated G-lycerins with a molecular weight of 1000 are used. The compressed foam obtained has a Ball drop rebound resilience of 36 percent and a density of 96.4 g / l.

Example "4

Example 1 is repeated, but 80 parts of ground barite are added to the foamable polyurethane mixture. This When freely foaming, the mixture results in a foam with a density of about 43.3 g / l. The obtained compacted Foam has a falling ball rebound resilience of 29 percent, a load-bearing capacity of 0.67 kg / cm and a density of 178 g / l. When comparing these values with the results of Examples 1, 2 and the comparative example (see table) shows that the incorporation of a filler leads to foams with improved load-bearing capacity and that these too Foams still have a low rebound elasticity. "

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Example 5

Example 4 is repeated, but instead of 80 parts only 20 parts of barite are used, so that a foam with a density of about 30.4 g / l is formed when foaming freely. To When compressed, this foam has a falling ball rebound resilience. of 33 percent, a load capacity of 0.52 kg / cm and a density of 143 g / l.

Claims

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Claims (12)

- 19 claims 1 . Process for the production of elastic, compressed polyurethane foams made of foamable polyurethane compositions, which are a polyol component and containing an isocyanate component (a) foaming the polyurethane mixture to form a partially cured foam mass, (b) Compressing this foam mass with the application of pressure to about 2/3 to I / ^{10 of its original volume 0 to about 1} 10 minutes after the end of the rise time, the temperature during the period from 0 to about 10 minutes to about 7 to 205 ° 0, and
(E) complete curing of the foam mass with removal of the Pressure, characterized in that the polyol component a mixture of a low molecular weight polyol (I) having a molecular weight of about 100 to 1500 and one high molecular weight polyol (II) with a molecular weight of about 2000 to 10,000 in a weight ratio of (I): (II) of about 1: 9 to 4: 1 used. 2. The method according to claim 1, characterized in that there is used as polyols (I) and (II) polyether polyols. 3. The method according to claim 2, characterized in that the polyether polyols used are alkoxylated polyhydric alcohols. BAD ORSGiNAL 209 8 27/1019 4. The method according to claim 3, characterized in ₅ - "ate was used as alkoxylated polyhydric alcohols oxypropylated C ^: .oerin. 5. The method according to claim 1 to 4, characterized in that a polyol (I) 'with a · molecular weight of about 150 to 1000 and a polyol (II) having a molecular weight of about 2500 to 6000 is used. 6. The method according to claim 1 to 5, characterized in that ' that a weight ratio of polyol (I): polyol (II) from about 1: 5 to 2: 1 used. 7. The method according to claim 1 to 6, characterized in that a polyurethane mixture is used, the tolylene diisocyanate, Water and a mixture of an amine and a tin ~ (II) salt contains as a catalyst. 8. The method according to claim 1 to 7, characterized in that that a polyurethane mixture is used which is about 10 to 100 percent by weight, based on the weight of the polyol component, contains a filler. 9. The method according to claim 8, characterized in that öaP man barite used as filler. 10. The method according to claim 1 to 9, characterized in that for a period of 0 to about 2.5 minutes from the end of the rise to rare pressure application, the partially cured Schaummaese at ambient temperatures of about 7 to 205 ⁰ C, preferably about 7 to 94 ° G, with a ¹ period of about 209827/1019 bad ORIGINAL 2.5 "to 5 minutes at ambient temperatures of about 7-94 ⁰ C _v vorzugsv / eiae 7 to 38 ⁰ C and a period of. About 5 to 10 minutes at ambient temperatures of about 44- 7 to ⁰ C, preferably from about 7 to 3O ⁰ C, holds. 11. The method according to claim 1 to 10, characterized in that the partially cured foam mast; e from the end of the rise time to the application of pressure 0 to about 10 minutes at ambient temperatures of about 21 to 44 ⁰ C. 12. Method according to claim 1, characterized in that polyurethane mixtures are used, which are used in free foaming Foams with densities of about 12.8 to 64 g / l and, after the application of pressure, foams with a density of about 24 to 240 g / l. BAD ORIGINAL 2 0 9 8 2 7/1019