JP5878357B2 - Polyurethane foam and seat pad - Google Patents

Description

  The present invention relates to a polyurethane foam and a seat pad using the same, and more particularly to a polyurethane foam and a seat pad excellent in wet heat compression characteristics without deterioration of other characteristics.

Among polyurethane foams, flexible polyurethane foams have excellent elastic tactile sensation, and are therefore used as impact cushioning materials in automobile seat cushions, seat backs, furniture articles and the like.
Conventionally, there has been an increasing demand for weight reduction and density reduction for polyurethane foams, but in recent years, there has been a demand for strength against compression at high temperatures and high humidity (wet heat compression characteristics). Development was desired.

  Here, in order to improve the wet heat compression characteristics of the polyurethane foam, how to suppress the reaction between the urea bond in the urethane resin and water molecules becomes a point. For this reason, conventionally, water used as a raw material for polyurethane foam is reduced to reduce the amount of urea bonds during urethane formation, and by adding a crosslinking agent to the raw material to form steric hindrance, water molecules are bonded to urea. In general, it has been a common practice to improve the wet heat compression characteristics using a technology that makes it difficult to attack.

  However, the above-described technology for reducing water in the raw material is accompanied by a problem that the foaming ratio of the polyurethane foam itself is lowered and cannot meet the needs for weight reduction. Further, the technique of adding a crosslinking agent to the raw material has a problem of adversely affecting other physical properties (elongation characteristics), although it is effective for improving wet heat compression characteristics.

  In Patent Document 1, a polyol compound and an isocyanate compound are reacted in the presence of a foam stabilizer, a foaming agent, and a urethanization catalyst to obtain a flexible polyurethane foam. A polyol compound containing 40% by mass or more of polyoxyalkylene polyol (X) which is 10 to 70 mg KOH / g and the ratio of oxyethylene groups in all oxyalkylene groups (100% by mass) is 50% by mass or more, As a foam stabilizer, a flexible polyurethane foam produced by a method using a foam stabilizer containing a silicone compound having a polysiloxane chain and a polyoxyalkylene chain and having an HLB value of 6 or more is disclosed. According to this polyurethane foam, it is possible to ensure a certain wet heat compression characteristic.

  However, the technique disclosed in Patent Document 1 cannot sufficiently satisfy the required wet heat compression characteristics. In addition, there is a problem that the weight cannot be reduced while maintaining the hardness.

JP 2006-316198 A

  The present invention has been made under such circumstances, and by using the polyurethane foam excellent in wet heat compression characteristics without degrading other characteristics by optimizing the blending components in the raw material, and using the same The object is to provide a seat pad.

  As a result of intensive studies to achieve the above object, the present inventor can incorporate water molecules into the hollow silica by blending the hollow silica into the raw material of the polyurethane foam. It was found that the reaction between urea bonds and water molecules can be suppressed, so that high wet heat compression characteristics can be obtained.

  However, the hollow silica has the property of adsorbing water molecules at around room temperature and releasing the adsorbed water molecules at around 120 ° C, so when used in the raw material as it is, it adsorbs once after molding the polyurethane foam. The released water molecules may be released, causing the inside of the polyurethane foam to expand and break (puncture). Therefore, by further including a foam stabilizer made of a linear siloxane-oxyalkylene block copolymer in the raw material of the polyurethane foam, the air permeability in the molded polyurethane foam can be improved, resulting in the destruction of the inside of the polyurethane foam. The inventors have found that excellent wet heat compression characteristics can be obtained without generating them, and have completed the present invention.

The present invention has been made based on such findings, and the gist thereof is as follows.
(1) formed from a raw material containing a foam stabilizer comprising a polyol, isocyanate, water, hollow silica, and a linear siloxane-oxyalkylene block copolymer ,
The polyurethane foam, wherein the hollow silica is a shirasu balloon .

(2) The polyurethane foam as described in (1) above, wherein the hollow silica has a particle size in the range of 5 to 40 μm.

( 3 ) The polyurethane foam as described in (1) above, wherein the hollow silica is contained in the raw material in a range of 0.1 to 3.0% by mass.

( 4 ) The polyurethane foam as described in (1) above, wherein the foam stabilizer is contained in the raw material in a range of 1.5 to 4.0% by mass.

( 5 ) A seat pad using the polyurethane foam described in (1) above.

  According to the present invention, it is possible to provide a polyurethane foam excellent in wet heat compression characteristics and a seat pad using the polyurethane foam without deterioration of other characteristics.

<Polyurethane foam>
The polyurethane foam according to the present invention is formed from a raw material containing a foam stabilizer made of polyol, isocyanate, water, hollow silica, and a linear siloxane-oxyalkylene block copolymer.

  By including hollow silica in the raw material, water molecules can be taken in when forming polyurethane foam, and the reaction between urea bonds and water molecules in the polyurethane foam can be suppressed, resulting in high wet heat compression characteristics. it can. In addition, by including a foam stabilizer made of a linear siloxane-oxyalkylene block copolymer in the raw material, the air permeability in the molded polyurethane foam can be improved. Therefore, the hollow silica contains water molecules. The internal destruction of the polyurethane foam due to the property of adsorbing at around room temperature and releasing the adsorbed water molecules at around 120 ° C. can be suppressed.

Hereinafter, the raw materials for the polyurethane foam according to the present invention will be described in more detail.
(Polyol)
Examples of the polyol contained in the raw material include dihydric to hexavalent polyhydric alcohols, polyoxyalkylene polyols (polyether polyols), polyester polyols, polymer polyols, and the like. Of these, polyether polyols and polyester polyols are preferably used, and polyether polyols are particularly preferably used. These polyols may use only 1 type, or may use 2 or more types together.

  The polyether polyol is preferably a polyether polyol obtained by ring-opening polymerization of alkylene oxide from the viewpoint of reactivity. Examples of such alkylene oxides include propylene oxide (PO) and ethylene oxide (EO). These may be used alone or in combination of two or more.

  Among these, from the viewpoint of raw material activity, the polyether polyol is preferably a polyether polyol obtained by copolymerization of the PO and the EO. Examples of the polymerization initiator include pentaerythritol and glycerin. The blending ratio of PO and EO during copolymerization is usually 8/92 to 18/82 (molar ratio) as EO / PO (molar ratio), preferably 13/87 to 15/85 (molar ratio). is there. When EO / PO (molar ratio) is out of the above range, it may be difficult to produce a polyether polyol.

  Further, the number of hydroxyl groups contained in one molecule of the polyether polyol is usually 2 to 4, particularly preferably 3. If the number of hydroxyl groups is too large, the raw material viscosity may increase, and if it is too small, the physical properties of the molded article may decrease.

  Further, it is preferable to use a polyether polyol having a low degree of unsaturation. More specifically, a polyether polyol having an unsaturation degree of usually 0.07 meq / g or less, preferably 0.04 meq / g or less is used. When the degree of unsaturation in the polyether polyol exceeds 0.07 meq / g, the durability and hardness of the polyurethane foam molded article of the present invention may be impaired. In the present invention, “unsaturation” is measured by a method in which acetic acid liberated by acting mercuric acetate on unsaturated bonds in a sample is titrated with potassium hydroxide in accordance with JIS K 1557-1970. The total degree of unsaturation (milli equivalent / g).

  In addition, about the said polymer polyol, it is possible to use a general purpose polymer polyol. More specifically, for example, a polymer polyol obtained by graft copolymerizing a polyether polyol with a polymer component such as polystyrene, polyacrylonitrile, or acrylonitrile-styrene copolymer can be given. The alkylene oxide used as a raw material for the polyether polyol (polyalkylene oxide) preferably includes propylene oxide, and particularly preferably includes propylene oxide alone or includes both propylene oxide and ethylene oxide. The proportion of the graft polymer component as described above in the polymer polyol is usually 25 to 50% by mass.

  In this invention, it is possible to mix | blend and use the said polyether polyol and the said polymer polyol in the said raw material. When the polymer polyol is blended with the polyether polyol, it is preferable in that the hardness of the foam can be increased. On the other hand, when it is not blended, the rebound resilience of the obtained polyurethane foam molded article is further improved. It is suitable at the point which can be made. When the polyether polyol and the polymer polyol are blended and used, the blending ratio is usually 30/70 to 100/0, preferably 40/60 as (polyether polyol) / (polymer polyol) (mass ratio). ~ 80/20. If the blending ratio of the two deviates from the above range, the physical properties of the polyurethane foam molded article of the present invention may be deteriorated or a reaction failure may occur.

  The number average molecular weight of each polyol is 1000 to 10,000, preferably 2000 to 5,000. If the number average molecular weight is too large, the stirring efficiency of the polyurethane foam stock solution may be inferior. On the other hand, if it is too small, the resilience of the resulting polyurethane foam may be greatly reduced. In the present invention, the number average molecular weight is a value calculated as a polystyrene equivalent value by the GPC method.

  In addition, about each said polyol, a commercial item can be used, for example, E-3030 (Molecular weight 3000, f (functional group number. The same hereafter) = 3, Asahi Glass Co., Ltd. polyether type polyol), V3943A (base polyol molecular weight) 3000, f = 3, Dow Polyurethane Japan Co., Ltd. acrylonitrile / styrene 43% graft copolymer polyol), 3P56B (molecular weight 3000, f = 3, Takeda Pharmaceutical Co., Ltd. polyether polyol) .

(Isocyanate)
A known isocyanate can be used as the isocyanate contained in the raw material. For example, tolylene diisocyanate, diphenylmethane diisocyanate, triphenyl diisocyanate, xylene diisocyanate, polymethylene polyphenylene polyisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and the like can be mentioned, and these can be used alone or in combination of two or more. May be.

  Among these, it is preferable to use at least one of tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) as the isocyanate from the viewpoint of a molding density region. Here, the TDI is not particularly limited, but may be a mixture having a blending ratio of 2,4-TDI and 2,6-TDI of 80/20 to 50/50 (mass ratio). A mixture of 80/20 to 65/35 (mass ratio) is particularly preferable. The MDI is not particularly limited, and can be used regardless of its molecular weight distribution. For example, pure (Pure) MDI (4,4'-MDI), polymeric MDI, crude MDI, etc. It can be used suitably.

  In addition, about the said TDI and MDI, a commercial item can be used. For example, T-80 (manufactured by Sumitomo Bayer Urethane Co., Ltd.) can be used as the TDI, and 44V20 (crude MDI, manufactured by Sumitomo Bayer Urethane Co., Ltd.) can be used as the MDI.

  When the TDI and the MDI are used in combination, the blending ratio of the two is usually 20/80 to 90/10 (mass ratio), preferably 50/50 to 80/20 as the value of TDI / MDI (mass ratio). (Mass ratio).

  The amount of the isocyanate is not particularly limited, but is usually 20 to 100 parts by mass, preferably 25 to 60 parts by mass with respect to 100 parts by mass of the total polyol. If the blending amount of the isocyanate is too small, the resinification reaction proceeds too much, resulting in closed cells and a suitable sheet may not be obtained. On the other hand, if the amount is too large, curing of the polyurethane foam may be delayed.

  In addition, the proportion of the isocyanate in the raw material (when two or more isocyanates are used in combination, the total amount of the isocyanate in the raw material) is an isocyanate equivalent (active hydrogen in the raw material). When the amount (mole) is 100, the equivalent (mole) ratio of isocyanate groups in the raw material is usually 80 or more, preferably 95 or more, and the upper limit is usually 120 or less, preferably 115 or less. If the isocyanate equivalent is less than 80, the resulting polyurethane foam may suffer from shrinkage failure, while if it exceeds 120, foam down may occur.

(water)
The water contained in the raw material serves as a foaming agent.
Although content of the water in the said raw material is not specifically limited, It is preferable that it is 0.1-10 mass parts with respect to 100 mass parts of said polyols, and it is more preferable that it is 0.5-5 mass parts.

  In addition to the water, the blowing agent is at least one selected from methylene chloride, low-boiling hydrocarbons, low-boiling fluorine-containing hydrocarbons, and inert gases (air, nitrogen, carbon dioxide, etc.). Further known foaming agents can also be used. It is preferable to select the above-mentioned foaming agent as appropriate according to requirements such as the expansion ratio.

(Hollow silica)
About the hollow silica contained in the said raw material, it is a material for enabling the improvement of the wet heat compression characteristic of a polyurethane foam by taking in water inside. The type of the hollow silica is not particularly limited, and for example, a shirasu balloon can be used.

  The size of the hollow silica is not particularly limited, but those having an average particle diameter of 5 to 40 μm are preferably used. Hollow silica with an average particle size of less than 5 μm has a low ability to release carbon dioxide generated when polyurethane foam is cured to the outside, so that sufficient wet heat compression characteristics cannot be obtained, while an average particle size of more than 40 μm Hollow silica may be inappropriate due to poor cohesive strength of the polyurethane foam after molding. In addition, the average particle diameter in this invention is a median diameter measured on a volume basis.

  Moreover, it is preferable that 0.1-3.0 mass% of the said hollow silica is contained in the said raw material. When the content of the hollow silica is less than 0.1% by mass, since the hollow silica is small, water molecules cannot be taken in sufficiently and the desired wet heat compression characteristics may not be obtained. If it exceeds 3.0% by mass, since the hollow silica is too much, the cohesive strength of the polyurethane foam after molding becomes poor and it may be difficult to use as a product.

(Foam stabilizer)
The foam stabilizer contained in the raw material is composed of a linear siloxane-oxyalkylene block copolymer. By using the linear siloxane-oxyalkylene block copolymer, the air permeability in the polyurethane foam can be improved.

  Moreover, it is preferable that the said foam stabilizer is contained in the said raw material in 1.5-4.0 mass%. If the content is less than 1.5% by mass, the amount of the foam stabilizer is too small, which may cause shrinkage and puncture of the polyurethane foam. On the other hand, if the content exceeds 4.0% by mass, the amount of foam stabilizer increases. As a result, too much air permeability may be produced, which may cause collapse of the polyurethane foam.

(Other ingredients)
In addition to the components described above, the raw material may further contain a catalyst, a crosslinking agent, and other additives as necessary.

  About a catalyst, it is used in order to make the said polyol and isocyanate react. As for the type of catalyst, for example, amine-based and tin-based catalysts are preferably used. Examples of amine catalysts include tetramethylhexamethylenediamine, pentamethyldiethylenetriamine, dimethylcyclohexylamine, bis- (dimethylaminoethyl) ether, tetramethylpropylenediamine, trimethylaminoethylpiperazine, tetramethylethylenediamine, dimethylbenzylamine, methylmorpholine, Examples of tin-based catalysts such as ethylmorpholine and triethylenediamine include stannous octate and dibutyltin dilaurate. These may be used alone or in combination of two or more. Among them, triethylenediamine is suitably used for promoting resinification, and diethanolamine is suitably used for controlling the breathability of the resulting foam. As a compounding quantity of a catalyst, it is 0-5 mass parts normally with respect to 100 mass parts of all the polyols, Preferably it is 0.1-1 mass part.

  The cross-linking agent has a molecular weight having two or more hydroxyl groups and having a hydroxyl value exceeding 280 mgKOH / g, or having two or more functional groups having active hydrogen such as primary amino groups and secondary amino groups. It is preferred to use less than 400 compounds. Specific examples include polyhydric alcohols such as pentaerythritol, diglycerin, dextrose, sorbitol, sucrose; polyols obtained by adding alkylene oxide to the polyhydric alcohols; monoethanolamine, diethanolamine, ethylenediamine, 3, 5 -Diethyl-2,4 (or 2,6) -diaminotoluene (DETDA), 2-chloro-p-phenylenediamine (CPA), 3,5-bis (methylthio) -2,4 (or 2,6)- Diaminotoluene, 1-trifluoromethyl-4-chloro-3,5-diaminobenzene, 2,4-toluenediamine, 2,6-toluenediamine, bis (3,5-dimethyl-4-aminophenyl) methane, 4 , 4′-diaminodiphenylmethane, m-xylylenediamine, 1,4 Diaminohexane, 1,3-bis (aminomethyl) cyclohexane, amine compounds such as isophorone diamine. Two or more crosslinking agents may be used in combination.

  Other additives are appropriately selected according to need. For example, fillers such as potassium carbonate and barium sulfate; antioxidants such as antioxidants and ultraviolet absorbers; flame retardants, colorants and antifungal agents. And anti-discoloring agents.

<Method for producing polyurethane foam>
The polyurethane foam according to the present invention is produced by reacting the above-mentioned specific polyol and isocyanate in the presence of the above-mentioned foam stabilizer, water, catalyst and the like. As a method for molding the flexible polyurethane foam, a reaction injection molding method in which a reactive mixture is directly injected into a mold using a low pressure foaming device or a high pressure foaming device is preferable. In addition, the flexible polyurethane foam of the present invention can be produced by either a cold cure method or a hot cure method, and the cold cure method is preferred.

<Seat pads and other products>
The seat pad according to the present invention is characterized by using the polyurethane foam according to the present invention. Thereby, a seat pad excellent in wet heat compression characteristics can be obtained.
In addition to the seat pad, a molded article using the polyurethane foam of the present invention is useful for mattresses, for example.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

(Example 1, Comparative Examples 1-3)
Each raw material for polyurethane foam was prepared by blending the components shown in Table 1 in the proportions in the same table.
Then, the polyurethane foam used as a sample was produced by foam-molding each prepared raw material by the one-shot method on the conditions of foaming liquid temperature: 25-35 degreeC, and foaming mold temperature: 55-65 degreeC.

* 1 Polyether polyol A: KC282, manufactured by Sanyo Chemical Co., Ltd.
* 2 Polyether polyol B: Asahi Glass Co., Ltd. EL555
* 3 Polymer polyol: Mitsui Chemicals POP3628
* 4 Shirasu Balloon: Fuji Balloon H-40 manufactured by Fuji Silysia Chemical Ltd., average particle size of about 40 μm
* 5 Catalyst: DAVCO 33LV, manufactured by Kao Farmin DM1098
* 6 Silicone foam stabilizer A: B8742 manufactured by Evonik, dimethylsiloxane-ethylene oxide block polymer * 7 Silicone foam stabilizer B: L626 manufactured by Momentive, linear siloxane-oxyalkylene block copolymer * 8 Isocyanate TDI / MDI: 4: 1 (mass ratio) blend of TDI-80 (manufactured by Sumitomo Bayer Urethane Co., Ltd., TDI) and 44V20 (manufactured by Sumitomo Bayer Urethane Co., Ltd., Crude MDI)

(Evaluation)
Then, the following evaluation was performed about each obtained sample.

(1) Wet heat compression characteristics Based on JIS K6401, the compression residual strain (%) after wet heat aging of each sample was measured. The measurement results are shown in Table 2. In addition, about compressive residual strain, it turns out that there is no residual strain and it is excellent in wet heat compression characteristics, so that it is small.

(2) Presence or absence of puncture For each sample with size: 350mm x 350mm x 70mm, overall density: 45g / L, after crushing operation, the polyurethane foam was cut and visually confirmed to make puncture (in the hollow silica The presence or absence of internal destruction of the polyurethane foam due to the property of releasing water molecules adsorbed on the water was confirmed.

  From Tables 1 and 2, it was found that the sample of Example 1 showed good results for both the wet heat compression characteristics and the presence or absence of puncture. On the other hand, although Comparative Example 1 and 3 had no puncture, the wet heat compression characteristics were inferior, and Comparative Example 2 showed that the wet heat compression characteristics were good but puncture occurred.

  According to the present invention, it is possible to provide a polyurethane foam excellent in wet heat compression characteristics and a seat pad using the polyurethane foam without deterioration of other characteristics.

Claims (5)

Formed from a raw material containing a foam stabilizer comprising a polyol, isocyanate, water, hollow silica, and a linear siloxane-oxyalkylene block copolymer ,
The polyurethane foam, wherein the hollow silica is a shirasu balloon .   The polyurethane foam according to claim 1, wherein the hollow silica has a particle size in the range of 5 to 40 µm.   The polyurethane foam according to claim 1, wherein the hollow silica is contained in the raw material in a range of 0.1 to 3.0 mass%.   The polyurethane foam according to claim 1, wherein the foam stabilizer is contained in the raw material in a range of 1.5 to 4.0% by mass.   A seat pad comprising the polyurethane foam according to claim 1.