KR20100054284A - Preparation method of polyurethane foam for sound absorbing material of automobile floor mat - Google Patents

Abstract

PURPOSE: A manufacturing method of a polyurethane foam for a vehicle floor mat sound absorbing material is provided to reduce the density of the polyurethane foam for 30~40% compared to a conventional polyurethane foam. CONSTITUTION: A manufacturing method of a polyurethane foam for a vehicle floor mat sound absorbing material comprises a step of reacting a modified polyisocyate including 25~40wt% of isocyanate group and polyol with urethane. The polyol is formed by mixing 90~97wt% of high molecular weight polyol and 3~10wt% of low molecular weight polyol. The modified polyisocyate is obtained by mixing 100wt% of resin premix and polymeric MDI, 30~60wt% of monomeric MDI, 5~20wt% of modified MDI, and 1~20wt% of TDI.

Description

Preparation method of polyurethane foam for automobile floor mat sound absorbing material {Preparation method of polyurethane foam for sound absorbing material of automobile floor mat}

TECHNICAL FIELD The present invention relates to polyurethane foams used as sound absorbing materials for automobile floor mats.

In the automobile floor mat, appropriate sound absorbing materials are used to maintain comfort in the vehicle from various external noise sources such as noise generated by an automobile engine and noise generated by friction between the tire and the road surface. Recently, maintaining quietness in cars has become an important factor for consumers to judge the quality level of passenger cars. For this reason, various studies have been actively conducted in terms of structural and raw materials in order to improve sound absorption performance. The automobile floor mat generally consists of the structure shown in FIG. The automobile floor mat is composed of a carpet fabric (1) on the upper surface, a layer of sound insulating material (2) made of a plate-like soft synthetic resin material, and a polyurethane foam (3) on the lower surface. The sound insulating material 2 of the synthetic resin material is called a heavy layer in this field.

As the sound insulation material 2 used to supplement the durability and sound insulation performance of the floor mat, soft synthetic resins such as polypropylene, polyethylene, and polyester resin are mainly used.

In general, in order to increase the sound absorption of automobile floor mats, urethane foams used herein require more open cells rather than closed cells and have a higher density.

On the other hand, automotive interior materials are required to be light within the range of performance.

If the weight of the interior material is heavy, not only will it increase the manufacturing cost but also adversely affect the environmental pollution at the time of disposal, but also increase the weight of the vehicle itself, which will also have a bad effect on fuel economy. Accordingly, development of lightweight polyurethane foams while maintaining high density is desired.

Recently, a method of reducing the weight of the interior material is being progressed to enhance fuel efficiency. However, in the case of the existing polyurethane foam for sound absorbing material, when the density is lowered, the sound absorbing performance is deteriorated and the properties such as tensile and tear strength are deteriorated. For this reason, currently used polyurethane foam is a situation that high density (85kg / m ³ or more) of the product is used.

In order to reduce the weight of the sound absorbing material, a heavy layer layer is removed, and a sound absorbing material for a floor mat using only a carpet fabric and a polyurethane foam has been introduced, but there is a problem in that sound absorption and durability are inferior.

The present inventors intend to provide a method for producing a polyurethane foam that maintains the sound absorbing performance of a conventional polyurethane foam while lowering the density of the polyurethane foam used for sound absorption on a floor mat.

It is an object of the present invention to provide a method for producing a polyurethane foam for automobile floor mat sound absorbing material to maintain sound absorption performance and durability while lowering the density of the polyurethane foam for sound absorbing material of automobile floor mat 30 to 40% compared to conventional commercial products. The purpose.

The present invention relates to polyurethane foams used for automobile floor mat sound absorption.

Polyurethane resins are prepared by urethane reaction of a polyisocyanate compound and a polyol compound.

Specifically, a resin is obtained by reacting a resin with a resin premix composed of a polyol, a catalyst and a foam stabilizer and an isocyanate.

Generally, polyurethane foams are obtained by reacting an isocyanate compound with a resin premix consisting of a polyol, a catalyst, a crosslinking agent and a blowing agent.

In order to develop a light weight sound absorbing material, until recently, a low density sound absorbing material product has been developed by increasing the content of a blowing agent or changing the content of a polyol used. However, the product developed in this way was not able to be applied in actual production because the loss of the excellent sound absorption performance, which is a characteristic of the polyurethane product, without the density reduction is large.

In order to solve this problem, the lightweight polyurethane foam for sound absorption material developed by our company does not use aliphatic diols and diamines, which are used as crosslinking agents, to maintain the strength of polyurethane foam when preparing resin premixes, unlike conventional polyurethane foams. Do not. The material used as a crosslinking agent was maintained in the foam strength, but was excluded from the prescription due to the problem of increasing the density by enhancing the adhesion between molecules. Instead of developing resin premix which adds a high molecular weight polyol and a low molecular weight polyol for the purpose of maintaining elasticity while maintaining the strength, isocyanate is used to reduce the density through the foaming force. Low density using modified isocyanate products made by blending Polymeric MDI, Monomeric MDI, Modified MDI and TDI. In addition, the company has developed polyurethane products for sound absorbing materials that are equal to or better than existing products in terms of foam strength and sound absorption performance.

Polyol is composed of -CHx- structure except -OH group which is a functional group at the end.As a result, the higher the molecular weight, the more the amount of -CHx- increases elasticity, and the empty space increases, which is effective in reducing the density of urethane foam. to be. However, there is a problem that the hardness indicating strength is weakened, but low molecular weight polyol is mixed therein to maximize the elasticity while preventing the decrease in hardness. This isocyanate product is mixed to increase NCO% compared to the existing product to strengthen foaming force and to react with isocyanate with enhanced hardness and elasticity, thus reducing the weight of the automobile flow mat sound absorbing material that maintains existing properties even at a density of 60kg / m ³ or less. Polyurethane foam was developed.

The present invention uses a mixed polyol obtained by mixing 3 to 10 wt% of a low molecular weight polyol having a molecular weight of 1000 or less with 90 to 97 wt% of a high molecular weight polyol having a molecular weight of 6500 or more, and polyisocyanate is mono to 100 wt% of a polymer M.D.Eye. Merrick M.D.I 30 ~ 60% by weight, modified M.D.I (Kumho Mitsui Chemicals, cosmonate LK) 5 ~ 20% by weight and T.D.I 1 ~ 20% by weight A polyurethane foam was prepared using a modified polyisocyanate containing 25 to 40 wt% of isocyanate group (-NCO) by performing time reaction, thereby lowering the density by 30 to 40% and lowering the sound absorbency compared to a polyurethane prepared using a conventional crosslinking agent. And a method for producing a polyurethane foam for automobile floor mat sound absorbing material having excellent durability.

The weight percent in the modified polyisocyanate manufacturing process is weight percent based on the polymer M.D.E.

Polyurethane foams that have been used for sound absorbing materials are resin premixes containing polyether polyols having a molecular weight of 3,000 to 5,000 and crosslinking agents composed of aliphatic diols and diamines, and amine or metal catalysts and foaming agents for reactivity control. Isocyanate is reacted to produce polyurethane foams. The reason why the polyether polyol is used here is that polyether polyol is advantageous to polyester polyol rather than polyester polyol in order to open a closed cell of the foam to form an open cell. Polyurethane foams for sound absorbing materials of this type are actively used because they exhibit excellent sound absorption performance compared to other polymer materials.

The lightweight polyurethane foam for sound absorbing material of the present invention, unlike conventional polyurethane foam, does not use aliphatic diols and diamines which are used as crosslinking agents to maintain the strength of the polyurethane foam when preparing resin premixes, and has high elasticity and strength. Molecular weight polyols are used and the isocyanate compounds are referred to as polymeric diphenyl methane diisocyanate (hereinafter referred to as polymeric M. di.oc.) and monomeric diphenyl methane diisocyanate (hereinafter referred to as monomeric). M. di, i)), modified diphenylmethane diisocyanate (hereinafter referred to as modified M. di. Is), and modified toluene diisocyanate (hereinafter referred to as modified T. di. Is) Low density and foam strength and sound absorption Utilities, were equally or develop a good sound-absorbing material for polyurethane foam compared to conventional products.

The polyol used in the production of polyurethane is a polyether polyol having a molecular weight of 6,000 or more and a terminal hydroxyl group (-OH) of 2 to 4, and a polyether polyol having a molecular weight of 300 to 1,000 and a terminal hydroxyl group (-OH) of 2 to 4 Ether polyols are mixed and used. In addition, it does not generally use a crosslinking agent used to strengthen the hardness.

The catalyst used is not different from the range of conventional polyurethane foams for sound absorbing materials, and amine catalysts, metal catalysts, and the like are used. Amine catalysts include triethylamine, dimethylcyclohexylamine, bisdimethylaminoethyl ether, tripropylamine, N-methyl morpholine, and metal catalysts include titanic acid esters, iron compounds, and tin compounds. And the amount is 0.01 to 10.0% by weight relative to the resin premix 100% by weight of the catalyst can be used alone or mixed.

As a blowing agent, water, which is a chemical blowing agent, is used alone, and the amount used is 0.1 to 15% by weight compared to 100% by weight of resin premix, and an organosilicon foaming agent for maintaining a stable foam structure contains 0.1 to 10.0% by weight of resin premix. And a polyurethane foam composition for sound absorbing material prepared by reacting polyisocyanate containing isocyanate group (-NCO) with 25 to 40% by adjusting the index to 0.5 to 2.0. In the present invention, various stabilizers, fillers, antibacterial agents, flame retardants, colorants, inorganic and organic fillers and the like can be used as necessary.

The isocyanate index is calculated as follows.

Polyisocyanate used in the present invention is a monomeric M.D.I (Kumho Mitsui Chemicals, 100 parts by weight of the polymer M.D.I (Kumho Mitsui Chemicals, product name: Cosmonate M-200) produced by the company) Product Name: Cosmonate PH) 30-60% by weight, modified M.D.I (Kumho Mitsui Chemicals, Trade Name: Cosmonate LK) 5-20% by weight and T.D.I. The reaction is carried out for 5 hours to prepare modified polyisocyanate containing 25 to 40% of isocyanate group (-NCO). Cosmonate LK product is a modified Mdiay used here.In order to solve the problem that monomeric Mdiay is solid at room temperature, it is partially modified by carbodiimidation reaction to make liquid properties at room temperature. Say.

Polyurethane foam produced by the method of the present invention has the effect of keeping the density low 50 ~ 60kg / ㎥ lightweight and excellent sound absorption and durability.

The present invention will be described in detail with reference to the following Examples.

Next, as shown in [Table 1], a high molecular weight polyether polyol, a catalyst, an organosilicon foam stabilizer, and ion-exchanged water, which are components of a resin premix, are mixed in the amount shown in [Table 1] to form a resin premix, and an isocyanate group The polyisocyanate polymerized so that (-NCO) is 25-40% is taken at index 0.7, mixed, stirred, and injected into a 1000 × 1000 × 20 mm aluminum square mold heated to 40-70 ° C. at a density of 55 kg / m ³ to close the lid. The foam molded in the mold was demolded for 2 to 3 minutes from the start of stirring the resin premix and the polyisocyanate composition, and then measured for the next day strength, elongation, tensile strength, tear strength and sound absorption performance, and [Table 1] and FIG. Shown.

Comparative Example 1

As a polyurethane foam for sound absorbing materials, a resin premix is prepared by mixing polyether polyol, a crosslinking agent, a catalyst, an organosilicon foam stabilizer, and ion-exchanged water in the amounts shown in [Table 1], and an isocyanate group (-NCO) is 10. The polyisocyanate in the prepolymer form containing ~ 60% is taken at index 0.7, mixed, stirred, and injected into a 1000 × 1000 × 20 mm aluminum square mold heated to 40 to 70 ° C. at a density of 85 kg / m ³ to close the lid. The foam molded in the mold was demolded after 2-3 minutes from the start of stirring the resin premix and the polyisocyanate composition, and measured the strength, elongation, tensile strength, tear strength and sound absorption performance of the next day, and are shown in [Table 1] and FIG. It was.

Comparative Example 2

As shown in the following [Table 1], as the density reduction foam of the polyurethane foam for sound absorbing materials, the polyether polyol, the crosslinking agent, the catalyst, the organosilicon foaming agent, and the ion-exchanged water were used in the amounts shown in [Table 1]. Mix the resin to make a resin premix, and take the polyisocyanate in the prepolymer form containing 10-60% of isocyanate group (-NCO) as index 0.7, mix and stir, and then mix and stir to the 1000X1000X20mm aluminum square mold heated to 40 ~ 70 ℃. Inject m ³ to close the lid. The foam molded in the mold was demolded after 2-3 minutes from the start of stirring the resin premix and the polyisocyanate composition, and measured the strength, elongation, tensile strength, tear strength and sound absorption performance of the next day, and are shown in [Table 1] and FIG. It was.

-Sound absorption performance evaluation

Sound absorption performance is the value measured by the absorption meter (SCIEN company make, model name Acoustic duct. Sp-9031).

In Figures 2, 3 and 4, the absorption ratio 1 means that 100% of the generated sound is absorbed, and the higher the sound absorption rate, the better the sound absorption. The frequency (Hz) can be divided into the low range of 1600 ~ 2000Hz and the high range of 5000Hz or more, and the sound absorption performance in the high range greatly affects the overall sound absorption performance.

The product of Example 1 was much better in sound absorption in the high sound region than the comparative product.

[Table 1] Composition and Properties of Resin Premix

Unit: gr

 NO. Example Comparative Example 1 Comparative Example 2  Resin Premix Prescription (Weight)  Polyol A # 1) 95 - -  Polyol B # 2) 5 - -  Polyol C # 3) - 100 90  Polyol D # 4) - - 10  Ion-exchanged water (foaming agent) 4.8 4.0 4.5  Foam stabilizer # 5) 1.0 0.5 0.5  Diethanolamine (crosslinking agent) - 0.5 0.5  Amine catalyst # 6) 0.05 0.2 0.2  Urethane Catalyst # 7) 1.1 - 0.55  Cell Opener # 8) 3.0 3.0 3.0  Isocyanate A # 9) 73.1  Isocyanate B # 10) 75.4 83.6  Isocyanate Index 0.7 0.7 0.7 Molding density (kg / m ³ ) 55 85 60 Elongation # 11) 151.1 161.1 112.3 Tensile Strength (kgf / cm ² ) # 12) 1.63 2.16 1.31 Tear strength (kgf / cm) # 13) 1.22 1.04 0.65

# 1) Polyether polyol obtained by addition polymerization of propylene oxide and ethylene oxide with glycerin as initiator, OHV 28mg KOH / g, molecular weight 6,500

# 2) Polyether polyol obtained by addition polymerization of propylene oxide and ethylene oxide with glycerin as initiator, OHV 240mg KOH / g, molecular weight 700

# 3) Polyether polyol obtained by addition polymerization of propylene oxide and ethylene oxide with glycerin as initiator, OHV 28 mg KOH / g, molecular weight 5,000

# 4) Polyether polyol prepared by dispersing acrylonitrile and styrene monomer in polyether polyol obtained by addition polymerization of propylene oxide and ethylene oxide as an initiator, OHV 28mg KOH / g, molecular weight 6,000

# 5) Foaming agent, product of Airproduct, brand name DABCO DC-5043

# 6) Amine catalyst, product of OSI company, brand name A-1

# 7) Urethane catalyst, product made by KAO, trade name No.25

# 8) Polyether polyol obtained by addition polymerization of propylene oxide and ethylene oxide as cell opener and glycerin as initiator, OHV 52mg KOH / g

# 9) NCO 33.5% polyisocyanate

# 10) NCO 28.5% polyisocyanate

# 11) Elongation, according to ASTM D-638

# 12) Tensile strength, according to ASTM D-638

# 13) Tear strength, according to the method of ASTM D-624

1 is a view showing the structure of a general automotive floor mat.

Figure 2 is a graph evaluating the sound absorption performance of the polyurethane foam prepared by the method of Example 1 in the present invention.

Figure 3 is a graph evaluating the sound absorption performance of the polyurethane foam prepared by the method of Comparative Example 1 in the present invention.

Figure 4 is a graph evaluating the sound absorption performance of the polyurethane foam prepared by the method of Comparative Example 2 in the present invention.

* Description of the symbols for the main parts of the drawings *

1: carpet fabric

2: Heavy Layer

3: polyurethane foam

Claims (2)

In the method for producing a polyurethane foam, Resin premix consisting of polyol, diethanolamine, foaming agent, urethane catalyst, and bubble-opening agent, which are composed by mixing 90-97% by weight of high molecular weight polyol having a molecular weight of 6500 or more with 3-10% by weight of low molecular weight polyol having a molecular weight of 1000 or less; 100% by weight of the polymer M.D.Eye is mixed with 30 to 60% by weight of the monomeric M.D.Eye, 5 to 20% by weight of the modified M.D.Eye and 1 to 20% by weight of the T.D.Eye A method of producing a polyurethane foam for automobile floor mat sound absorbing material by urethane-reacting a modified polyisocyanate containing 25 to 40% by weight of an isocyanate group as an isocyanate index of 0.5 to 2.0. The method for producing a polyurethane foam for automobile flow carpet sound absorbing material according to claim 1, wherein the molding density of the polyurethane foam is 60 kg / m ³ or less.

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