CA2287121A1

CA2287121A1 - A foaming composition of soft polyurethane

Info

Publication number: CA2287121A1
Application number: CA002287121A
Authority: CA
Inventors: Sang Hwa Lee; Byoung Jin Lee; Heon Hee Park; Jong Yoon Lim
Original assignee: Hyundai Motor Co; Kumho Mitsui Chemicals Inc
Current assignee: Hyundai Motor Co; Kumho Mitsui Chemicals Inc
Priority date: 1998-11-18
Filing date: 1999-10-25
Publication date: 2000-06-07
Also published as: KR100303258B1; KR20000032833A

Abstract

The present invention relates to a foaming composition of soft polyurethane used for the cushion insert for vehicles and more specifically, to a foaming composition of soft polyurethane which comprises polymerpolyol whrein solid polymer synthesized from acrylonitrile or styrene monomer is grafted or dispersed in polyetherpolyol, polyol whrein polyetherpolyol is mixed, crosslinkage agent, amine catalysts, foaming agent and organic silicon defoaming agent, and which provides greatly improved productivity and reduced inferiority owing to the natural crushing of independent foam cells through chemical method rather than physical method.

Description

A FOAMING COMPOSITION OF SOFT POLYURETHANE
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a foaming composition of soft polyurethane used for the cushion insert for vehicles and more specifically, to the foaming composition of soft polyurethane which provides greatly improved productivity and reduced inferiority owing to the natural crushing of independent foam cells through chemical method rather than physical method by reacting resin pre-mix containing polymerpolyol wherein solid polymer synthesized Erom acrylonitrile or styrene monomer is grafted or dispersed in polyetherpolyol, polyol wherein polyetherpolyol is mixed, crosslinking agent, amine catalysts, foaming agent and organic silicon defoaming agent with organic polyisocyanate.
~ 5 Soft foams for seat cushion mold are divided into cold cure mold foams and hot cure mold foams depending on the manufacturing method. In the manufacture of hot cure mold foams, artificial cell-opening process is unnecessary because the foamed cell is naturally opened through chemical reaction in the mold. However, in the manufacture of cold cure mold foams, zo artificial cell-opening process (hereinafter referred to as "crushing") has been required because the closed cell is formed. In the manufacture of hot cure mold foams, the source solution is injected at 35-40 C of mold temperature and the foam is solidified at 100-200 C . For cold cure mold foams, the source solution is injected at relatively high mold temperature of 50-70 C and the foam is 25 solidified at relatively low temperature of 50-70 C . The resulting foams contain a certain amount of closed cells and they cause the constriction of the foams.
Therefore, the cold-cure type mold foams need crushing process. The closed cells have been opened either by crushing of passing the foams through a circular frame with narrower width than the foams or by crushing of vacuumizing the foams.
The conventional soft foams for cold cure mold are manufactured by injecting mixture of isocyanate and resin premix in the mold heated to 50-70 C
and solidifying for 3-10 min. The formed foams are processed with crushing in order to open the closed cells. In spite of the advantage of fast solidification at low temperature, the crushing of the closed cells included in the foams render the increase of the cost of utilities, electric power, manpower and other expenditures. Therefore, a new technology which excludes crushing by naturally opening the foams through chemical reaction of isocyanate and resin premix is being required.
SUMMARY OF THE INVENTION
The inventors made intensive efforts to solve the problems. As a result, it ~ s was realized that with the reaction of resin premix containing polymerpolyol wherein solid polymer synthesized from acrylonitrile or styrene monomer is grafted or dispersed in polyetherpolyol, polyol wherein polyetherpolyol is mixed, crosslinking agent, amine catalysts, foaming agent and organic silicon defoaming agent with organic polyisocyanate, the foam yield is greatly 2o improved, and the crushing process becomes unnecessary due to the increased crushability due to the naturally open cells through chemical reaction.
Accordingly, an object of this invention is to provide a foaming composition of soft polyurethane which provides greatly improved productivity and reduced inferiority owing to the natural crushing of 25 independent foam cells through chemical method rather than physical method.
Detailed Description of the Invention The present invention is characterized by a 1:0.5-1:1.5 equivalence ratio mixture of foaming composition of soft polyurethane comprising:
(a) resin premix containing 80-95 wt% of polyol mixture wherein polyetherpolyol with 2-4 functional groups and molecular weight of 6,000-10,000 and polymerpolyol wherein solid polymer synthesized s from acrylonitrile or styrene monomer is grafted or dispersed in polyetherpolyol with the molecular weight of 4,000-8,000 are mixed in the range of 95:5-50:50 wt%, 0.01-2.0 wt% of amine or glycol crosslinking agent, 0.2-3.0 wt% of a tertiary amine catalyst, 2.0-5.0 wt% of water and 0.1-2.0 wt% of organic silicon defoaming agent;
and (b) organic polyisocyanate containing 20-40 wt% of isocyanate group.
The detailed description of the present invention is given hereunder.
The present invention is characterized by manufacturing naturally ~ s crushed soft polyurethane mould foams by the chemical reaction of resin premix and organic polyisocyanate in the mould.
The foaming composition of the present invention comprises resin premix and organic polyisocyanate. The resin premix is prepared by adding crosslinking agent, catalyst, foaming agent and organic silicon defoaming agent 2o to a polyol mixture of polyetherpolyol and polymerpolyol.
The polyol mixture contained in the resin premix is prepared by mixing polyetherpolyol which has 2-4 functional groups, of which at least 13 mod % is primary hydroxyl group, and whose molecular weight is 6,000-10,000 and polymerpolyol wherein solid polymer synthesized from acrylonitirle or styrene ?s monomer is dispersed or grafted in polyetherpolyol with 2-4 functional groups, of which at least 13 mol % is primary hydroxyl group, and whose molecular weight is 4,000-8,000 in the range of 95:5-50:50 wt%. If the mixing ratio is beyond the above range, the solidity, formation and physical properties of the foams deteriorate. The preferable mixture ratio is 85:15-65:35.
The resin premix is prepared by adding crosslinking agent, catalyst, foaming agent and organic silicon defoaming agent to the above polyol mixture.
Glycol or amine crosslinking agents are used. Examples include ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, pentaerythlitol, diethanolamine, triethanolamine, ethylenediamine, triethyltetramine, methyleneorthochloroaniline, 4,4-diphenylmethanediamine, 2,6-dichloro-4,4-diphenylmethanediamine, 2,4-toluenediamine and 2,6-toluenediamine. The desirable content of the crosslinking agent is 0.1-2.0 wt% of the total resin premix. If the content is less than 0.1 wt%, crosslinkage of the resin premix is insufficient, and if it exceeds 2.0 wt%, it requires the crushing process due to the increased independent cells.
For catalyst of the present invention, even though polyurethane foams i a used for the conventional catalysts can be used, a tertiary amine catalyst is desirable. One or a mixture of more than one selected from the group consisting of triethylamine, bisdimethylaminoethyl ether, tripropylamine, triisopropanediolamine, tributylamine, triethylamine, N-methylmorpline, diethylenetriamine bis(2-(N,N-diethylamino)ethyl)ether and their salts can be 2o used. The desirable content of the catalyst is 0.2-2.0 wt% of the total resin premix. If the content is less than 0.2 wt%, the reaction is retarded so that the solidification and productivity becomes poor. And if the catalyst content exceeds 2.0 wt%, there arises a problem such as reduced endurance or fogging of the foams.
~5 Water used for the foaming agent is desirable to be in the range of 2.0-5.0 wt% of the total resin premix.
Organic silicon defoaming agent plays a role of preventing the unification or destruction of cells and forming uniform cells, when isocyanate and water react to produce gaseous carbon dioxide and the gas expands to form cells due to the heat of reaction. Common organic silicon defoaming agent used for the manufacture of soft cold cure mould foams can be used either alone or mixed. The desirable content is 0.1-2.0 wt% of the total resin premix.

5 Various stabilizing agent, filling agent, coloring agent, deflaming agent or settling agent can be used together if necessary.
The said resin premix and organic polyisoisocyanate with 20-40 wt% of isocyanate groups are mixed in the range of 1:0.5-1:1.5 equivalence ratio and reacted to obtain opened soft cold cure mould foams. If the isocyanate group content of the polyisocyanate is less than 20 wt°o, the specific gravity increases, and if it exceeds 40 wt%, problems such as solidity and soldifying rate arise.
The mechanical strength (extensibility, heat resistance and tension resistance) of the opened-cell soft polyurethane foams prepared by the present invention is superior to the closed-cell soft polyurethane foams.
~ 5 The resin premix and poly isocyanate are mixed in the range of 1:0.5-1:1.5 equivalence ratio and injected to a mold heated to 50-70 C to prepare soft cold cure mold foams.
"Index" means a stoichiometric index of isocyanate reacting with the compound having active hydrogens in the resin premix. Index of isocyanate is ?o calculated by the following equation.
Index of Isocyanate = (Isocyante amount actually used)/ (Theoretically required isocyanate amount) After mixing the resin premix and organic polyisocyanate, the mixture is stirred and inserted into a 200x 200X 200um~ open box to foam freely. The 2s sinking height after the foam is defoamed at the maximum height is expressed in % to measure the settling. The reaction mixture is injected into a 400x 400X 100mm aluminum test mould preheated to 50-70 C, 20% excessively of the minimum filling amount, and the mold is capped. After taking out the foams 5 min after the stirring of resin premix and organic polyisocyanate, the crushability is evaluated by measuring the difference of the force required to compress the same 50% firstly and the force required to compress the same 50%
secondly with universal test machine. Crushability is the measuring of the force required to open the closed-cells in the foams and it provides a criterion for determining if the crushing process is necessary or not. The less the crushablility, the less the closed-cells.
The test results of the soft polyurethane mould foams prepared from the present invention show greatly improved productivity and reduced inferiority.
i o The following examples are intended to be illustrative of the present invention and should not be construed as limiting the scope of this invention defined by the appended claims.
Examples 1-6 ~ s Organic polyisocyanate whose toluenediisocyanate content is 20-~0 wt%
of the total isocyanate and isocyanate group content is 36.5 wt% was used.
Resin premix was prepared by mixing polyol, water, catalyst, crosslinking agent and organic silicon defoaming agent as in the following Table 1. 2008 of the resin premix regulated to 25~ 1 C was mixed with 92g of 20 organic polyisocyanate. After stirring vigorously for 5 sec, the same was injected into a 200X 200X 200mm box. After measuring the settling, the central part of the foams was bisected by 100X 100X 50utm in order to measure the core density the following day. The result is shown in Table 1.
Settling and core density decreased with the increase of crosslinking 2s agent.

Table 1 Examples Polyol A~> 280 280 280 280 280 280 Polyol Bz~ 120 i20 120 120 120 120 Polyol C'~ 10 10 10 10 10 10 Resin HzO4~ 14 14 14 14 14 14 premix L-30025 2.8 2.8 2.8 2.8 2.8 2.8 SRX-274CG~ 1.2 1.2 1.2 1.2 1.2 1.2 ~ t DABCO 33LV'~ 1.08 1.40 0.40 1.08 1.08 1.08 NTAX A-1"~ 0.6 0.48 0.6 0.6 0.6 0.6 ~

I
DEOA''~ 2.0 2.0 2.0 0.0 0.8 4.0 IsocyanateMC-70'~ 198.0 198.0 198.0191.8 194.3 204.2 Index ~ 95 95 95 95 95 95 Settling 8.8 7.1 4.6 15.5 12.2 8.3 (%) , Core density 42.0 39.6 37.7 43.9 41.7 37.3 (!cg/
m') '~ Polyether polyol prepared by additional polymerization of propylene oxide and ethylene oxide with glycerin as initiator, OHV 26n~
KOH/g '-~ Polymerpolyol prepared by dispersing acrylonitrile and styrene monomer in polyether polyol prepared by additional polymerization of propylene oxide and ethylene oxide with glycerin as initiator, OHV 28n~
KOH/g '~ Polyether polyol prepared by additional polymerization of propylene oxide and ethylene oxide with glycerin as initiator, OHV 56mg KOH/g ~~ Distilled water or ion exchange water 5~ Organic silicon surfactant, Witco Co.

6> Organic silicon surfactant, Torey Co.

~ Amine catalyst, Air Product Co.

~> Amine catalyst, Tosso Co.

9> Crosslinking agent, diethanolamine, Korea Polyol Co.

1~> NCO%
36.5 Kumho Mitsui Chemical Co. Ltd.

Examples 7-12 Resin premix was prepared as in the following Table 2. 2008 of the resin premix regulated to 25~ 1 C was mixed with 92g of organic polyisocyanate.
After stirring vigorously for 5 sec, the same was injected to a 200X 200X
200mu~

box. After measuring the settling, the central part of the foams was bisected by 100x 100x 50mm in order to measure the core density the following day.
Generally, settling provides the determination of stable cell structure. If a value of settling is small, the cell structure is stable and the forming is favorable.
However, the increased closed cells render the artificial cell-opening process. If a value of settling is large, the cell is unstable and formation weight increases.
Therefore, small settling with large crushability is desirable.
Resin premix was prepared by mixing polyol, water, catalyst, crosslinking agent and defoaming agent as in Table 2. 640g of the resin premix regulated to 25~ 1 C was mixed with 2758 of organic polyisocyanate with 50.Ok~;/ tn' of excess density. After stirring vigorously for 5 sec, the same was injected to a 400X 400x 100utm aluminum mold. The mold was capped and five minutes after stirring, crushability was determined by measuring the difference of the force required to compress the same 50% firstly and the force required to ~5 compress the same 50% secondly with universal test machine.
With the increase of crosslinking agent content, the settling and density decreased and the crushablity became poor. The crushability improved with the decrease of the ratio of resin catalyst (DABCO 33LV) and urea catalyst (NIAX
A-1). However, it was unfavorable to minimize the density due to the increased 2o settling.
Table 2 Examples Polyol A 420 420 420 420 420 420 PolyolB 180 180 180 180 180 180 Polyol C 15 15 15 15 15 15 Resin Hz0 21 ~ 21 21 21 21 21 ~

premix L-3002 4.2 4.2 4.2 4.2 4.2 4.2 SRX-274C 1.8 1.8 1.8 1.8 1.8 1.8 DABCO 33LV 1.62 2.1 2.4 1.62 1.62 1.62 NTAX A-1 0.9 0.72 0.6 0.9 0.9 0.9 DEOA 3.0 3.0 3 0 0.0 1.2 6.0 IsocyanateMC-70 297.0 297.0 297.0 287.7 291.4 306.3 Index 95 95 95 95 95 95 Settling 8.8 7.1 4.6 15.5 12.2 8.3 (%) Core density 42.0 39.6 37.7 43.9 41.7 37.3 (k~/ ~
m') Crushability~~ 0.0 6.5 26.3 0.0 0.0 2.7 ~~ Force-to-Crush, Icg/314cv~
(400x 400x l0mm), Difference of forces required to compress the sam le 50% firstl and secondl Examples 13-18 Resin premix was prepared as in the following Table 3. 2008 of the resin premix regulated to 25~ 1 C was mixed with 92g of organic polyisocyanate.
After stirring vigorously for 5 sec, the same was injected to a 200x 200X
200mm box. After measuring the settling, the central part of the foams was bisected by 100X 100x 50mm in order to measure the core density the following day. Also, resin premix was prepared by mixing polyol, water, catalyst, crosslinking agent and defoaming agent as in Table 3. Resin premix regulated to 25~ 1 C was mixed with organic polyisocyanate with 55.Okg/ rn' of excess density. After stirring vigorously for 5 sec, the same was injected to a 400X 400X 100mm aluminum mould. The mould was capped and five minutes after stirring, crushability was determined by measuring the difference of the force required to compress the same 50% firstly and the force required to compress the same t s 50% secondly with universal test machine.
Crushability varied with the contents of primary, secondary and tertiary amines. With the increase of primary and secondary amines, the settling and density decreased and the crushability became poor. Namely, with the increase of primary amines, noncrushing became unfavorable.
Table 3 Examples Polyol A 490 490 490 490 490 490 Polyol B 210 210 210 210 210 210 Polyol C 17.5 17.5 17.5 ~ 17.517.5 17.5 Resin Hz0 21 21 21 21 21 21 premix L-3002 4.9 4.9 4.9 4.9 4.9 4.9 SRX-274C 2.1 2.1 j 2.1 2.1 2.1 2.1 DABCO 33LV 1.89 2.45 2.8 2.8 2.8 2.8 ' IVTAX A-1 1.05 0.84 0.7 0.7 0.7 0.7 DEOA 7.0 7.0 7.0 0.0 1.4 3.8 IsocyanateMC-70 297.8 297.8297.8 267.6 270.1 273.3 Index 95 95 95 95 95 95 Primary 3.89 3.79 3.76 0.10 0.51 1.81 amine, tllg KOH/g Tertiary 2.78 2.85 2.95 1.72 2.13 2.49 amine, mg KOH/g Settling 7.6 7.3 8.7 11.0 4.9 5.2 ( % ) Core density 43.5 41.3 40.7 49.1 43.2 41.7 (kg/ nt' ) Excess 54.7 54.9 55.2 55.0 54.9 54.8 density (kg/ m' ) Crushability 8.5 17.8 23.0 0 0 0.4 As described in detail above, the soft polyurethane foams of the present invention is prepared by reacting resin premix prepared by mixing polyol, which is a mixture of polyetherpolyol and polymerpolyol, amine or glycol crosslinking agent, tertiary amine catalyst, foaming agent and organic silicon defoaming agent with organic polyisocyanate in the predetermined equivalence ratio. The present invention provides greatly improved productivity and reduced inferiority owing to the natural crushing of independent foam cells through chemical method rather than physical method.

Claims

What is claimed is:

1. A 1:0.5-1:1.5 equivalence ratio mixture of a foaming composition of soft polyurethane which comprises:
(a) resin premix containing 80-95 wt% of polyol mixture wherein polyetherpolyol with 2-4 functional groups and molecular weight of 6,000-10,000 and polymerpolyol wherein solid polymer synthesized from acrylonitrile or styrene monomer is grafted or dispersed in polyetherpolyol with the molecular weight of 4,000-8,000 are mixed in the range of 95:5-50:50 wt%, 0.01-2.0 wt% of amine or glycol crosslinking agent, 0.2-3.0 wt% of tertiary amine catalyst, 2.0-5.0 wt% of water and 0.1-2.0 wt% of organic silicon defoaming agent; and (b) organic polyisocyanate containing 20-40 wt% of isocyanate group.