AU9819698A

AU9819698A - Process for molding polyurethane using an internal demolding agent, and molding products obtained

Info

Publication number: AU9819698A
Application number: AU98196/98A
Authority: AU
Inventors: Denis Ghesquiere; Daniel Loc'h
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1997-12-26
Filing date: 1998-12-24
Publication date: 1999-07-15
Anticipated expiration: 2018-12-24
Also published as: EP0926173A1; PT926173E; ES2237829T3; ZA9811797B; FR2773163A1; JPH11315154A; FR2773163B1; AU753689B2; EP0926173B1; DE69829265T2; ATE290553T1; DE69829265D1; CA2256973A1; BR9805688A

Abstract

Diester of at least one aliphatic, aromatic, alicyclic or dimeric diacid and at least one linear or branched aliphatic monoalcohol is used as an internal mold release agent in the moulding of polyurethanes. Process for moulding polyurethanes comprises charging a mold with a mixture of: (a) at least one isocyanate prepolymer, (b) at least one organic hydroxylated compound capable of reacting with (a), and (c) an internal mold release agent consisting of at least one diester of at least one aliphatic, aromatic, alicyclic or dimeric diacid and at least one linear or branched aliphatic monoalcohol, the diester having a total of 24-52 (26-36) C atoms. Independent claims are included for: (1) a process as claimed in which microcellular soles for shoes are molded; (2) molded products made using the process and (3) shoes having soles molded using the process.

Description

V/UU/U11 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: PROCESS FOR MOLDING POLYURETHANE USING AN INTERNAL DEMOLDING AGENT, AND MOLDING PRODUCTS OBTAINED The following statement is a full description of this invention, including the best method of performing it known to us PROCESS FOR MOLDING POLYURETHANE USING AN INTERNAL DEMOLDING AGENT, AND MOLDING PRODUCTS OBTAINED The present invention relates to a process for molding polyurethane, in which an internal demolding agent is used, as well as to the molded products obtained by this process, in particular shoes with a molded sole.

It is known practice to mold polyurethane by introducing, into an open or closed mold, a mixture containing an isocyanate prepolymer and at least one hydroxylated compound, in particular a polyether polyol or a polyester polyol having a functionality at least equal to 2, which can react with the isocyanate prepolymer, as well as various additives such as expansion agents, catalysts, stabilizers and fillers or reinforcing agents.

It is known practice to spray on to the molds, before they are used, an external demolding agent, such as a wax or a silicone, generally in the form of solutions in a solvent or in the form of an aqueous dispersion. In the absence of internal demolding agent, it is necessary to carry out a new spraying operation on the surface of the mold after each demolding operation.

It is moreover known practice to add to the mixture to be molded an internal demolding agent, the purpose of which is to allow several demolding operations to be carried out before it is necessary to respray with external demolding agent. The higher the number of demolding operations, the more the rate of molding can be increased and, consequently, the more cost-effective the process. In addition, the quantitative reduction of the use of external demolding agent also entails a reduction in the manufacturing cost and leads to an improvement in ecological terms on account of the reduced amount of solvent evaporated into the atmosphere, as well as the amount of external demolding agent sprayed outside the mold.

2 It is also known practice, for example from US-A-5,389,696, to introduce into the mixture to be molded, in a proportion of 1 to 10% by weight relative to the total weight of the mixture to be molded, an internal demolding agent containing mixed esters containing 1) diacids, 2) polyols and 3) monocarboxylic acids containing 12 to 30 carbon atoms. It is expressly indicated, in column 2, lines 35-38, that this agent must not contain any esters of diacids and of aliphatic monoalcohols containing from 12 to 30 carbon atoms.

When such an agent is used, it is difficult to measure out since it is difficult to mix with the prepolymer and/or the polyol.

According to the present invention, it has been found that certain diesters can be used alone as internal demolding agent, with a better result than that obtained with the mixture recommended by patent US-A-5,389.696, although they are explicitly excluded in that patent.

The subject of the present invention is, consequently, a process for molding polyurethane, according to which a mixture containing at least one isocyanate prepolymer and at least one hydroxylated organic compound which can react with said prepolymer is introduced into a mold, an internal demolding agent being added to said mixture, characterized in that said internal demolding agent consists of at least one diester of at least one aliphatic, aromatic, alicyclic or dimeric diacid and of at least one linear or branched aliphatic monoalcohol, said diester containing 24 to 52 carbon atoms in total, preferably 26 to 36 carbon atoms. A diester of a monoalcohol containing a number of carbon atoms of between 7 and 14 is preferably used.

The diesters used can be, for example, diisodecyl phthalate, diisoundecyl phthalate, diisotridecyl phthalate, diisononyl adipate, diisodecyl adipate, diisotridecyl adipate, di-n(C12-C14)alkyl 3 adipate, 2-ethylhexyl dodecanedioate, n-octyl dodecanedioate, the ester of a dimer of oleic acid and of 2-ethylhexyl alcohol (2-ethylhexyl dimerate) and the ester of a dimer of oleic acid and of n-octyl alcohol (n-octyl dimerate), these diesters making it possible to mold products in a single unit, in particular in the form of a layer of unique density.

Diisotridecyl phthalate, diisotridecyl adipate, di-n(C12-C14)alkyl adipate, 2-ethylhexyl dodecanedioate, n-octyl dodecanedioate, 2-ethylhexyl dimerate and n-octyl dimerate are preferably used, which make it possible to manufacture both products molded in a single unit of unique density and those in the form of two coupled separate parts, in particular of 1-ayers which may be of different density and which adhere together. In a particularly preferred manner, diisotridecyl phthalate, diisotridecyl adipate, n-octyl dodecanediaote and n-octyl dimerate are used, diisotridecyl phthalate and diisotridecyl adipate being particularly preferred.

It has been found that these diesters, in the active proportions defined below, are sufficiently easy to mix with the isocyanate prepolymer and/or with the hydroxylated compound capable of reacting with the prepolymer, for it to be possible to introduce them into the mold as a mixture with the prepolymer, as a mixture with the hydroxylated compound(s) capable of reacting with the prepolymer, or as a mixture with both. Furthermore, the diesters according to the invention can be introduced independently into the mixing head of the molding machines at the same time as the other components of the mixture. This introduction method is particularly favorable when the diester is a dimerate.

The diesters according to the invention make it possible in particular to mold polyurethanes having a density of between 0.2 and 1.25 g/cm 3 this density being obtained in particular by varying the weight 4 percentage of the expansion agent in the overall mixture.

The amount of diesters added is between 1 and by weight relative to the total weight of the molding mixture. For amounts less than the number of molding operations which can be carried out after using an external demolding agent is not increased. For amounts greater than there is no further substantial increase in the number of demolding operations between two successive uses of external demolding agent. The external demolding agent preferably used is a mixture of linear and/or cyclic polydimethylsiloxanes and/or of polydimethylsiloxanes containing hydroxyl ends, with which the mold is coated initially and after a certain number of successive molding operations without coating.

The isocyanate prepolymer can be obtained from any isocyanate known for the preparation of polyurethanes, whether they be aliphatic, cycloaliphatic, aryl, arylaliphatic or heterocyclic isocyanates. Methylenediphenyl isocyanate is used, for example.

The hydroxylated compound can be a polyether polyol or a polyester polyol. According to the invention, a polyester polyol is preferably used, in particular a polyadipate. It can also contain polyols with a molecular weight of less than 400 as chain extenders.

The mixture to be molded can contain, in a known manner, additives other than the internal demolding agent. Mention may be made of expansion agents such as water, halogenated hydrocarbons, lowboiling solvents such as pentane, catalysts such as tertiary amines, emulsifiers or foam stabilizers, such as siloxanes, inorganic and organic fillers such as glass fibers, mica, talc, calcium carbonate or organic microspheres such as those sold under the brand name "Expandocel" by the company Nobel Industries. Additives 5 such as flame-retardants, antistatic agents, dyes and cell regulators can also be added. It should be noted that liquid diluents, such as a mineral oil, a plant oil or a cyclic olefin, are not generally added.

The use of the internal demolding agent according to the invention is particularly suitable for molding microcellular soles for shoes, in particular soles with closed cells. The soles can be manufactured separately and then fixed onto the stem of the shoe by bonding or they can be molded by direct injection onto the stem of the shoe. In this case, it has been found that the use of the diesters according to the invention makes it possible to maintain good adhesion of the polyurethane sole to the stem, in particular to a leather stem.

According to the present invention, it is also possible to prepare so-called "coupled" soles consisting of two layers: a relatively compact wear layer with a density of about 1 to 1.25, and a comfort layer with a lower density, of about 0.4. In this case, the stem can also be attached directly to the sole during the molding. It has been observed that the two layers adhere together satisfactorily and that the lowdensity layer adheres to the stem of the shoe when direct injection onto said stem is carried out.

The use of the diesters according to the invention makes it possible to carry out at least molding operations and up to more than 50 consecutive molding operations before it is necessary to reapply an external demolding agent to the surface of the mold.

The molding rate can thus be increased very considerably and, consequently, the manufacturing time and cost can be reduced, along with the pollution due to the evaporation of the solvent from the external demolding agent and also due to the spraying of external demolding agent outside the mold. The addition of the diesters according to the invention does not modify the reaction: it is possible to work at the same

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6 temperatures with the same proportions of products as in their absence.

The subject of the invention is also a molded product, and in particular a shoe sole, obtained by carrying out the process defined above, as well as a shoe whose sole is thus obtained.

The tests given below, purely as nonlimiting illustrative examples, will allow a better understanding of the invention to be gained.

General molding method The tests were carried out on two machines: 1) a machine sold by the company "Gusbi", in which the mixture to be molded is cast in an open mold, 2) a machine sold by the company "Desma", in which the mixture to be molded is injected into a closed mold.

The molds used are made of aluminum alloy.

Before any tests, they are cleaned thoroughly with N-methylpyrrolidone and then rinsed with methylene chloride and dried in the open air. They are thermostatically maintained at 40-45 0

C.

An external demolding agent (see Table V) is applied with a spray-gun into -the molds before the first molding operation. No other spraying is applied while it is possible to obtain soles or plates without bonding, without defects and, more generally, without any specific intervention.

The molds used are strictly of the same type as those used industrially for the manufacture either of unit soles (isolated molding) intended to be bonded to a shoe stem, or of soles of unique density directly injected onto a stem, or of soles of "coupled" type containing a wear layer of higher density and a comfort layer of lower density, which are successively injected. The plate molds have the following dimensions: 15 x 20 cm, and a variable thickness from to 1 cm.

7 In all cases, the demolding or mold-opening times were maintained at their standard value, i.e. the value used in the absence of internal demolding agent.

Depending on the polyurethane prepared and on the mold used, these times range between 1.5 and 3 minutes.

Products used for the molding operations They are obtained by reaction of a methylene diphenyl isocyanate (MDI) prepolymer with a polyol composition including a polyester polyol, which is a polyadipate.

Polyadipates Three types of polyadipate were used, which differ in the polyols used or in their molecular mass.

TABLE I Polyadipate Polyadipate I Polyadipate

II

Polyadipate

III

Polyols used (proportions in moles) Ethylene glycol 60% Diethylene glycol Ethylene glycol 70% Butanediol Ethylene glycol 70% Butanediol Molecular mass 2,000 2,000 3,000 Internal demolding agents The internal demolding agents used are given in Table II below.

TABLE II

DIESTER

Diisodecyl phthalate Diisoundecyl phthalate Diisotridecyl phthalat Diisononyl adipate Diisodecyl adipate I Total number of carbons Reference DEx DE1 30 DE2 e 34 DE3 24 nP4 24 TV~A n 8 Diisotridecyl adipate 32 DE6 C12-C14 di-n-alkyl adipate =31.6 DE7 2-Ethylhexyl dodecanedioate 28 DE8 n-Octyl dodecanedioate 28 DE9 2-Ethylhexyl dimerate 52 n-Octyl dimerate 52 DE11 Obtained from the C12/C14=70/30 mixture of alcohols "Nafol" 12-14 S from the company Condea Obtained with the dimeric acids "Pripol 1017" from the company Unichema Prepolymers Three types of prepolymers B and C) were prepared containing 16.5% of NCO as a function of the diester DEx concerned.

TABLE III Composition of the prepolymers Reference MDI polyadipate I

A

MDI polyadipate I 4% diester DEx BDEx MDI polyadipate I 7% diester DEx CDEx Polyol compositions A polyadipate, i.e. a polyester polyol, is mixed with various additives so as to obtain the compositions given in Table IV.

9 TABLE IV Reference Polyol composition by weight 1 Polyadipate II 95.40 Ethylene glycol (chain extender) 3.60 Triethylenediamine (catalyst) 1.00 2DEx Idem 1 2% diester DEx 3DEx Idem 1 4% diester DEx 4 Polyadipate II 88.55 Ethylene glycol (chain extender) 10.30 Triethylenediamine (catalyst) 0.40 NIAX silicone SR 393* (cell stabilizer) 0.40 Water (expansion agent) 0.35 Idem 4 2% diester DEx 6 Polyadipate III 89.45 Ethylene glycol (chain extender) 9.00 Triethylenediamine (catalyst) 0.70 NIAX silicone SR 393* (cell stabilizer) 0.40 Water (expansion agent) 0.45 7DEx Idem 6 2% diester DEx 8 Polyadipate II 89.95 Ethylene glycol (chain extender) 8.50 Triethylenediamine (catalyst) 0.60 NIAX silicone SR 393* (cell stabilizer) 0.40 Water (expansion agent) 0.55 9DEx Idem 8 2% diester DEx Idem 8 4% diester DEx 11 Polyadipate II 93.40 Ethylene glycol (chain extender) 5.60 Triethylenediamine (catalyst) 1.00 12DEx Idem 11 2% diester DEx_ NIAX silicone SR 393 silicone surfactant sold by the company "Witco Corporation" I 10 A prepolymer defined above in Table III and a polyol composition defined above in Table IV were introduced into molds in the weight proportions (prepolymer/polyol composition) indicated in Table V in column R. The components are thermostatically maintained at 45-50 0 C. The number of molding operations after a first spraying with external demolding agent until the need for a second spraying, and optionally after a second spraying until the need for a third spraying, were measured. The tests were carried out using a "Gusbi" casting machine or using a "Desma" injection machine. In the case of molding of singledensity layers (unit molding), the results are given in Table V below; in this table, the two tests in the first line correspond to the molding of plates, while the other lines correspond to the molding of soles.

TABLE V

MOLDINGS

Density Machine Polyol Prepolyiner R diester External Initial number Af ter 2nd in mixture demolding of molding spraying r!agent operations 1.2 Gusbi 1 A 0.54 0.0 AP 7014-89(1) 1.2 Gusbi 3DE6 A 0.53 2.6 AP 7014-89 40-45 40-45 1.2 Desma 1 A 0.53 0.0 AP 7014-89 1.2 Desma 3DE6 A 0.52 2.6 AP 7014-89 1.2 Desma 1 BDE6 0.54 1.4- AP 7014-89 20-25 20-25 1.2 Desma 1 CDE6 0.54 2.5 AP 7014-89 1.2 Desma i2DEl BDE1 0.68 2.8 FZ 3711(2) 10-12 1.2 Desma 11 A 0.70 0.0 FZ 3711 4-6 1.2 Desina 12DE2 -BDE2 0.69 2.8 FZ 3711 10-11 1.2 Desma 12DE3 JBDE3 0.68 2.8 FZ 3711 >3U* 1.2 Desma 2DE4 JBDE4 0.53 2.7 AP 7014-89 10-12 1.2 Desma 2DE5 BDE5 0.52 2.7 AP 7014-89 10-11 1.2 Desma 12DE5 BDE5 0.68 2.8 FZ 3711 1.2 Desma 3DE5 BDE5 0.53 4.0 AP 7014-89-10-12 1.2 Desma -12DE6 BDE6 0.68 2.8 FZ 3711 55 1.2 Desma. 12DE6 BDEG 0.68 2.8 Siliconol NM1-l00 1.2 Desma 12DE7 BDE7 0.68 2.8 FZ 3711 1.2 Desma 12DE8 BDE8 0.68 2.8 FZ 3711 1.2 Desrna 12DE9 BDE9 0.68 2.8 FZ 3711 24-25 1.2 Desma 2DE1O BDE10 0.54 2.7 AP 7014-89 27-28 1.2 Desma 12DEll BDE11 0.69 2.8 FZ 3711 12-14 0.55 Gusbi j4 A 1i.17 0*.OAP 7014-89 2-3 0.55 Gusbi 14 BDE6 1.17 j2.2 A P 7014-89 10-12 0.55 Gusbi JSDE6 BDE6 1.17 j3.1 AP 7014-89 15-20 0.55 Desma j6 A 1.02 10.0 AP 7fl1A-,QQ 0.55 Desma 6 CDE6 1.02 3.

0.55 Desma 7DE6 BDE6 1.02 3.

0.45 Desma 8 A 1.08 0.

0.45 Desma 8 BDE6 1.08 2.

0.45 Desma. 8 CDE6 1.08 13.

AP 7014-89 15-20 AP 7014-89 15-20 AP 7014-89 2-3 AP 7014-89 25-30 25-30 AP 7014-89 1>30* (1) (2) (3) -res stopped before the limit of the system was reache Deniolding agent from the company Air Products Silicone fluid FZ 3711 from the company Witco Corporat Silicone oil: polydimethylsiloxane from the company HUi ion ls 13 The polyurethanes with a density of 1.2 correspond to "coupled" sole wear layers, the polyurethanes with a density of 0.45 correspond to "coupled" sole comfort layers and the polyurethanes with a density of 0.55 correspond to monolayer soles (single-density).

These tests show that in the presence of the diesters of the invention, the number of possible molding operations between two successive sprayings with external demolding agent increases considerably.

Tests for molding two layers of different density by successive injections ("coupled" soles) were also carried out, the first layer corresponding to a wear layer with a density of 1.2 and the second layer corresponding to a comfort layer with a density of 0.45. A "Desma" injection machine was used. The results are given in Table VI below.

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TABLE VI COUPLED SOLES Wear layer (d 1.2) Comfort layer (d 0.45) External Number of molding demolding operations (1) Polyol Pre- R Polyol Pre- R agent After 1st After 2nd polymer diester polymer diester spraying spraying 1 A 0.54 0.0 8 A 1.08 0.0 AP 7014-89(2) 3-5 3DE6 A 0.53 2.6 10DE6 A 1.08 1.9 AP 7014-89 50 45-50 2DE6 BDE6 0.53 2.7 8 BDE6 1.08 2.1 AP 7014-89 30-35 30-35 2DE6 BDE6 0.53 2.7 9DE6 BDE6 1.06 3.0 AP 7014-89 12DE3 BDE3 0.68 2.8 9DE3 BDE3 1.06 3.0 FZ 3711(3) 56 45-50 11 CDE6 0.69 2.9 8 CDE6 1.08 3.6 FZ 3711 62 12DE9 BDE9 0.68 2.8 9DE9 BDE9 1.06 3.0 FZ 3711 12DEll BDE11 0.68 2.8 9DE11 BDE11 1.06 3.0 FZ 3711 13-16 Stopped before reaching the limit of the possibilities Number of possible molding operations without defects on the 2 layers, one or the other still possibly being acceptable AP 7014-89: Demolding agent from the company Air Products Silicone fluid FZ 3711 from the company Witco Corporation 15 In this case also, it is seen that in the presence of the diesters of the invention, the number of possible demolding operations between two successive sprayings with external demolding agent increases considerably.

On the coupled moldings corresponding to the fourth line of Table VI, according to standard EN 344 (paragraph the adhesion between the two layers was measured, which is 4.2 at 7.5 N/mm, and the adhesion between the comfort layer and a leather stem was measured, which is 6 to 10 N/mm. These adhesions are suitable since, for example, according to standard EN 344, the minimum value for the adhesion must be 4 N/mm.

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Claims

1. Process for molding polyurethane, according to which a mixture containing at least one isocyanate prepolymer and at least one hydroxylated organic compound which can react with said prepolymer is introduced into a mold, an internal demolding agent being added to said mixture, characterized in that said internal demolding agent consists of at least one diester of at least one aliphatic, aromatic, alicyclic or dimeric diacid and of at least one linear or branched aliphatic monoalcohol, said diester containing 24 to 52 carbon atoms in total.

2. Molding process according to Claim 1, characterized in that the diester or the weighted mixture of diesters contains 26 to 36 carbon atoms in total.

3. Molding process according to either of Claims 1 and 2, characterized in that the monoalcohol contains 7 to 14 carbon atoms.

4. Molding process according to one of Claims 1 to 3, characterized in that the diester is diisotridecyl phthalate or diisotridecyl adipate.

Molding process according to one of Claims 1 to 4, characterized in that the diester is introduced into the mold as a mixture with the prepolymer, the hydroxylated organic compound(s) or with both constituents.

6. Molding process according to one of Claims 1 to 4, characterized in that the diester is introduced independently into the mixing head of a molding machine containing the mold.

7. Molding process according to one of Claims 1 to 6, characterized in that the amount of diester introduced is between 1 and 5% by weight relative to the total weight of the molding mixture.

8. Molding process according to one of Claims 1 to 7, characterized in that the hydroxylated organic compound is a polyester polyol with a functionality of at least 2. 17

9. Molding process according to Claim 8, characterized in that the polyester polyol is a polyadipate.

Molding process according to one of Claims 1 to 9, characterized in that, initially and after a certain number of successive moulding operations, the mold is coated with an external demolding agent containing one or more linear and/or cyclic polydimethylsiloxanes and one or more polydimethylsiloxanes containing hydroxyl ends.

11. Molding process according to one of Claims 1 to characterized in that microcellular soles for shoes are molded.

12. Molding process according to one of Claims 1 to 11, characterized in that soles containing two layers of different density are molded.

13. Molded product obtained by carrying out the process according to one of Claims 1 to 12.

14. Shoe containing a sole molded by carrying out the process according to one of Claims 1 to 12. DATED this 24th day of December 1998. WITCO WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN. VIC. 3122. I