RO121125B1 - Flexible cold-polymerizable polyurethane system for motor vehicle parts industry - Google Patents

Abstract

The invention relates to a flexible cold-polymerizable polyurethane system based on polyether-polyols and diphenylmethanediisocyanate polymer for the motor-vehicle parts industry, which is the result of the reaction between a mixture comprising 100 parts by weight of polyether-polyol having the molecular mass Mm of 6000, the hydroxyl index of 28 mg KOH/g and the primary hydroxyl value of at least 70 mg KOH/g, 3.5...4 parts by weight of grafted polyol polymer having the hydroxyl index of 28 mg KOH/g, 3.5...4.2 parts by weight of water, 0.2 parts by weight of amine catalyst diazobicyclo-octane, 0.60...0.75 parts by weight of retarding catalyst 1-(dimethylaminoethyl)-4-methylpiperazidine, 0.3 parts by weight of silicone emulsifier and diphenylmethanediisocyanate polymer having a content of -NCO= groups of 28.3%, the density of 170 cP at a temperature of 25A C at a polyol component/isocyanate component mixing ratio of 100/60 corresponding to an isocyanate index I=0.90.

Description

The present invention relates to a flexible polyurethane system, cold polymerizable, based on a composition based on polyether-polyols and diphenylmethanesisocyanates polymers, used to obtain seat cushions for the automotive industry.

Flexible polyurethane foam compositions are known, having the polyolic component adapted to the cold or hot foaming system and using isocyanate systems based on toluendiisocyanate or diphenylmethanesocyanate, depending on the demands imposed on the respective landmarks from a physical-mechanical point of view.

Compared to the flexible, hot polymerizable, energy-intensive polyurethane systems, and the cold-working toluendiisocyanate-based polyurethane systems that require special molds and thermoregulatory equipment, diphenylmethanesisocyanate-based polyurethane systems are increasingly used. due to the technical-economic advantages they produce, their application requires minimal investments.

Seat cushions for the automotive industry must meet certain specific requirements, which result from the particular anatomical characteristics of the human body, from the behavior of the vehicle from the point of view of oscillations and vibrations, and from the mandatory criteria of road safety.

Thus, the car seat must:

- to support the user in safe conditions, in all possible situations during the journey;

- to ensure a uniform distribution of the pressure exerted by a person on the chair;

- to screen the driver in the best conditions against the vibrations, oscillations and shocks that occur as a result of the profile of the road and the constructive features of the vehicle;

- to give the user, in all possible situations, a full sense of comfort;

- have the lowest possible weight, without decreasing the physico-mechanical properties and functional parameters.

lately, the attention of the flexible polyurethane foam producers has turned to polio compositions mixed with isocyanates, without freon expansion agents, in order to protect the environment, whose physical-mechanical properties, following cold polymerization are comparable to those of polyurethane systems based on toluendiisocyanate.

It is known that two components are required to obtain polyurethane foams:

- component A or polyol component, containing: the basic polyol, crosslinking agents, catalysts, foaming agents, stabilizers, flame retardants, antioxidants and colorants;

- component B or isocyanate component, which may consist of a single isocyanate (toluendiisocyanate or diphenylmethanesisocyanate) or a mixture of two or more isocyanates contained in various ratios, depending on the physical-mechanical characteristics required.

The polyols commonly used in component A are either glycerine-based or trimethylol-propane-based polyethers that are block copolymerized with propylene and ethylene oxide, with ethylene oxide terminal blocks and high average molecular weights M, _n = 3500-7000, or graft polyethers, made by grafting styrene, acrylonitrile or chlorinated derivatives on the polyether chain.

Known compositions based on polyether-polyols for cold-polymerizable flexible polyurethane foams, for seat cushions, in combination with diphenylmethanesocyanates do not ensure the obtaining of physical-mechanical properties of endurance and weight similar to those obtained with flexible or polymerizable flexible polyurethane systems. systems using toluendiisocyanate.

RO 121125 Β1

The technical problem solved by the invention is to make a polyurethane system 1 based on polyether-polyols and polymeric diphenylmethanesisocyanate-like isocyanates for cold-polymerizable flexible polyurethane foams, with improved physical-mechanical properties and 3 weights of approximately low seat cushions. 20%, situation impossible to achieve with classic polyurethane systems using diphenylmethanesisocyanate applicable in the technology 5 of manufacture of seat cushions.

The flexible polyurethane system based on polyether-polyols and polyphenyl diphenylmethanesocyanate according to the present invention, eliminates the disadvantage of the classic polyurethane-polyol and polyphenylmethanesisocyanate compositions, cold polymerizable, because it is the result of the reaction of a mixture of 100. by weight polyether-polyol having a molecular weight M _m of 6000, hydroxyl index of 28 mg KOH / g and primary hydroxyl figure of at least 70 mg KOH / g, 3.5 ... 4 parts by weight polyol polymer graft having a hydroxyl OH index of 28 mg KOH / g, 3.5 ... 4.2 parts by weight water, 0.2 parts by weight catalyst 13 amine diazobicyclooctane, 0.60 ... 0.75 parts by weight catalyst of delay 1- (dimethylaminoethyl) -4-methylpiperazine, 0.3 parts by weight silicone emulsifier and diphenylmethanesisocyanate 15 polymer having a group content -NCO = 28.3% density at 25 ° C of 170 cP, at a ratio of ame each polyol component / isocyanate component of 100/60, corresponding to an isocyanate index I = 0.90.

The advantages of cold polymerizable polyurethane composition according to the invention are: 19

- obtaining free foam densities in the range of 40 ... 42 kg / m ³ , densities by about 20% lower than those of diphenylmethane-diisocyanate based polyurethane systems currently used in the production of car seat cushions;

- increase in productivity by about 15%; 2. 3

- reducing the weight of the foamed parts by about 20%;

- great flexibility in modifying the physical-mechanical properties of the poly-urethane system, by the variation of the ratio between components, respectively the variation of the isocyanate index in the range 0.85 ... 1.05. 27

The following is an example of embodiment of the invention:

In an industrial plant for the conditioning of the polyol components, it is dosed with 29% accuracy of 1%:

-100 parts by weight polyether-polyol with molecular weight M _m = 6000, hydroxyl index -31

OH - 28 mg KOH / g and primary hydroxyl figure of at least 70 mg KOH / g;

- 3.5 parts by weight polyol grafted polymer, having the hydroxyl index -OH = 22 mg 33 KOH / g;

- 3.8 parts by weight of water; 35

- 0.2 parts by weight diazobicyclooctane amine catalyst;

-0.7 parts by weight catalyzed by type 1- (dimethylaminoethyl) -4-methylpiperazine delay; 37

- 0,3 parts by weight silicone emulsifier, mixing the components according to the following process parameters: 39

- agitator speed: 75 rpm / min .;

- flow rate of the recirculation pump: 9 m ³ / h; 41

- mixing time: 3 h;

- mixing temperature: 23 ± 2 ° C.43

The polio component i that conditioned as in the example above, is mixed together with the diphenylmethanesisocyanate polymer (having a group content -NCO = 28.3%, density 45 at 25 ° C = 1.19 g / cm ³ and a viscosity of 170 cP), using a high pressure polyurethane foam injection machine, at a mixing ratio corresponding to an isocyanate index 47 of I = 0.9, respectively A / B = 100/60.

RO 121125 Β1

A polyurethane foam is obtained with the following characteristics:

- start time = 17 s;

- growth time = 55-58 s;

- density at free foam = 41 kg / m ³ ;

- tear resistance = 0.45 - 0.48 daN / cm;

- bearing = 1.90 -1.95 daN / dm ² ;

- elongation at break = 280%, (The analyzes were performed on standard specimens cut from a foam block with a dimension of 1x1x1 m.)

Claims (1)

Claim Flexible polyurethane system, cold polymerizable, based on polyether-polyols and diphenylmethanesisocyanate polymer for the auto parts industry, characterized in that it is the result of the reaction between a mixture of 100 parts by weight polyether-polyol having a molecular mass M _m of 6000, hydroxyl index of 28 mg KOH / g and primary hydroxyl number of minimum 70 mg KOH / g, 3.5 ... 4 parts by weight polyol grafted polymer having a hydroxyl index OH of 28 mg KOH / g, 3, 5 ... 4.2 parts by weight water, 0.2 parts by weight diazobicyclooctane amine catalyst, 0.60 ... 0.75 parts by weight late catalyst 1- (dimethylaminoethyl) -4-methylpiperazine, 0.3 parts by weight silicone emulsifier and diphenylmethanesisocyanate polymer having a group content -NCO = 28.3% density at 25 ° C of 170 cP, at a mixing ratio of polyol / isocyanate component of 100/60, corresponding to an isocyanate index 1 = 0.90.