JPH07148750A - Production of impact absorbing foam - Google Patents

Abstract

PURPOSE:To mass-produce a product excellent in impact absorbing characteristics and having stable quality by cutting hard resin foam produced by continuous foaming equipment so as to have a longitudinal cell structure so that the vertical direction of foaming is set to an impact absorbing direction to produce impact absorbing foam. CONSTITUTION:A foamable raw material is reacted in continuous foaming equipment having a mixing head 1 and a conveyor 2 to produce foam. At this time, the foamable raw material is foamed while the side guide plate 3 of the continuous foaming equipment is successively narrowed before the gel time of foaming reaction to form a hard resin foam 4 having a longitudinal foam cell structure. The foam 4 is cut so that the longitudinal direction of foamed cells coincides with an impact absorbing direction to produce impact absorbing foam. By this constitution, the impact absorbing foam wherein the vertical direction of foaming is certainly arranged in an impact absorbing direction is produced. Excellent absorbing characteristics is ensured with respect to a conventional molded product and a product of stable quality is mass-produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a shock absorbing foam for protecting a human body from a shock when a car or other vehicle collides.

[0002]

2. Description of the Related Art As a required characteristic of a shock absorber, the load increases as it compresses as shown in FIG. 1, but the load does not increase at any point and changes at a constant load. Is required. By having such characteristics, when the human body and the shock absorber collide, the speed is not rapidly changed and the shock is absorbed without significant repulsion, so that the brain and internal organs inside the human body are damaged. Can be made smaller. As such an impact absorbing foam, conventionally, a rigid polyurethane foam foamed in a closed mold having a desired shape is used. However, in the case of a molded foam product formed by a closed mold, it is generally difficult to exhibit the compression characteristics as shown in FIG. 2 and to have the characteristics as shown in FIG. As a result, the compression characteristic becomes elastic, the speed change when absorbing an impact is large, and the repulsion is also high, so that the human body is likely to be adversely affected. Further, in the case of foaming in a mold, there is a drawback that a certain reaction curing time is required for each mold, the production quantity is limited, the processing time is long, and the cost is high.

As a result of studying to solve such conventional problems, in order to obtain the compression characteristic as shown in FIG.
It has been found to be good to compress vertically long cells in the vertical direction. Considering the cause using a paper cylinder as a model, when compressing in the vertical direction as shown in FIG. 3, the load suddenly rises, then the structure breaks and buckles, so the load suddenly decreases, After that, a phenomenon in which the load decreases again due to structural failure after the load has increased again occurs randomly, and it is compressed with a peak that does not exceed the fracture strength level of the material until it completely collapses. On the contrary, when the compression is applied from the lateral direction, the load is elastically increased with the compression as shown in FIG.

In the case of urethane foam, it is considered that such cylinders are made up of innumerable combinations, and when compressing the cells in the longitudinal direction, when one cell is buckled by compression and the load falls, this time The phenomenon in which another cell is compressed and the load increases is repeated, and the cells are averaged in a larger number of cells, so it is presumed that the compression behavior is as shown in FIG. When the cells are compressed in the lateral direction, it is presumed that elastically changed objects are combined and thus elastically changed as a whole as shown in FIG. Therefore, in order to obtain the target characteristics, it is preferable to perform compression in the vertical direction of the cell with a vertically long cell structure.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an impact absorbing foam which has excellent impact absorbing properties, can be mass-produced, and has stable quality.

[0006]

The present invention relates to a method for producing a foam by reacting a foam raw material in a continuous foaming equipment, in which side guide plates of the continuous foaming equipment are sequentially fitted before the gel time of the foaming reaction. A method for producing a shock-absorbing foam, which comprises foaming to obtain a hard resin foam having a vertically long foam cell structure, and cutting and molding so that the longitudinal direction of the foam cells of the foam coincides with the shock-absorbing direction. Pertain to.

In the present invention, as the foamed resin, polyurethane, phenol resin or the like can be used. Here, the explanation will focus on the polyurethane foam that can be preferably used.

[0008] In the closed mold foaming of a normal rigid polyurethane foam, the shape tends to be spherical and the directionality is difficult to be constant, but the vertically long cell structure in the present invention means a structure in which the vertical diameter of the cell is larger than the horizontal diameter. In addition, even if the individual cell diameters are not uniform, those having a foam structure with a relatively large longitudinal diameter are also included.

In the present invention, the average cell size is preferably 0.15 mm to 1.5 mm, more preferably 0.2 mm to 0.7 mm. If the cell becomes too large, the fluctuation of the flat portion in FIG. 1 in the load / strain characteristic during compression becomes large, which is not preferable. And the aspect ratio of the cell is 1.3 / 1
The above is good, and 1.5 / 1 or more is more preferable.

The shock absorber of the present invention can be manufactured, for example, as follows.

Although it is difficult to give directionality to the cells by mold foaming, in the block in which the stock solution is continuously foamed by supplying the stock solution on the conveyor, only the lateral direction is constrained so that the cells become vertically long. However, at this time, by arranging the guide plates that are laterally constrained so as to be gradually narrowed as shown in FIG. 9, it is possible to promote the vertical lengthening of the cells. At this time, the reaction progresses, and it becomes difficult to fit the guide plate in a state where the gel time has passed and the resinification has progressed, so the gel time should be set before the gel time.

As the urethane material, the materials usually used for rigid polyurethane foam can be used. A semi-hard or soft urethane material is an elastic hardened material, so it is difficult to obtain the target compression characteristics. As the polyol component, polyester polyol, polyether polyol, polymer polyol, or a combination thereof is used, and a mixture of polyols such that the average hydroxyl value is 200 to 900 is used.

The polyether polyol is obtained by addition-polymerizing an alkylene oxide such as ethylene oxide or propylene oxide with an initiator having _two or more functional groups and having an OH group, an NH group or an NH ₂ group at the terminal. For rigid polyurethane foam, it is trifunctional or more and has a hydroxyl value of 200-200.
Those of 0 are preferably used. The polyester polyol may be either a condensation type polyester polyol or a lactone type polyester polyol obtained by a known method. The condensed polyester polyol is preferably a polyester polyol obtained by a condensation reaction of a saturated or unsaturated dibasic acid, acid anhydride, dialkyl ester or the like with glycols. The lactone-based polyester polyol is a polyester polyol obtained by ring-opening polymerization of lactones. The polymer polyol is obtained by graft-polymerizing a monomer having a vinyl group to a polyether polyol, and is preferably used for the purpose of adjusting hardness.

As the polyol component, a mixture of these polyols with several kinds of polyether polyols is used as a main component. Depending on the case, a polyol obtained by mixing a polyester polyol or a polymer polyol is added to an organic amine type or an organic type. A metal-based catalyst, or a surfactant such as silicon or an emulsifier for stabilizing the cell, and a low-boiling substance such as chlorofluorocarbon and water that reacts with it to generate carbon dioxide, etc. as a foaming agent. It is added and used as.

As the isocyanate component, all known bifunctional or higher polyisocyanates can be used. Tolylene diisocyanate (TDI), tolidine diisocyanate (TODI), naphthylene diisocyanate (ND)
I), xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (PAPI) and the like can be used alone or as a mixture, and a prepolymer obtained by adding a polyol is also used. it can. In this case, the isocyanate index is preferably 85 to 120, but can be appropriately adjusted according to the desired physical properties. The mixing method may be stirring mixing or collision mixing.

In the present invention, the phenol resin foam is obtained, for example, by mixing a phenol resin, a foaming agent, an acidic curing agent, etc., and foaming and curing.

The phenol resin is a resol-type phenol resin obtained by reacting phenols and aldehydes in the presence of an alkali catalyst such as sodium hydroxide, barium hydroxide, potassium hydroxide or ammonia, or phenols and aldehydes. A benzylic ether-type phenol resin obtained by reacting the above with a catalyst such as a non-alkaline metal compound such as zinc oxide, magnesium oxide, zinc borate, zinc naphthenate, etc. is used.

As the foaming agent, hydrocarbons such as petroleum ether, n-pentane, cyclohexane and n-hexane, halogenated hydrocarbons such as dichloromethane, trichlorotrifluoroethane, trichloromonofluoromethane, dichlorotrifluoroethane and chloropentane. Classes are generally used, and two or more kinds may be used in combination.

As the acid curing agent, inorganic acids such as phosphoric acid, hydrochloric acid and sulfuric acid, and organic acids such as phenolsulfonic acid, toluenesulfonic acid, xylenesulfonic acid, benzenesulfonic acid and methanesulfonic acid are used. You may use together 1 or more types.

The object of the present invention is to cut and mold a hard resin foam having a vertically elongated foam cell structure obtained by foaming by the above-mentioned specific method so that the longitudinal direction of the foam cell coincides with the impact absorption direction. It is possible to produce a foam having excellent impact absorption.

[0021]

In the shock absorber of the present invention, even if a sudden compression is applied to the cell, the load does not increase from a certain point and the load remains almost constant, so that a good and stable shock absorbing property can be obtained.

Further, in the foaming of the mold, the curing time is required for each mold, and the molding cycle becomes long. However, in this method, a large amount of foaming is required, so that the curing time required for one product is hardly required. Further, since there is no skin layer, it is possible to reduce the weight of the molded foam product.

[0023]

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

Example 1 A polyol component is prepared by mixing the following materials. 1) Mixture of polypropylene glycol (average hydroxyl value 290): 100 parts 2) Silicon foam stabilizer for hard urethane foam: 2 parts 3) Tertiary amine-based urethane-forming catalyst: 0.7 parts 4) H ₂ O ... 1.5 parts Polyol component 100, isocyanate component 94 with NCO% 31% is continuously stirred and mixed in mixing head 1 while continuously feeding onto a conveyor lined with release paper, The width of foaming reaches the point where the raw material reaches the gel time
The lateral guide plates 3 are sequentially set to set from 1400 mm to 1200 mm and set, and after the gel time has passed, set and foamed so that the width of foaming becomes constant, and the specific gravity of the rigid polyurethane foam is 0.07 continuous. The foamed product 4 is created.

The foamed product was cut and molded into a predetermined shape to prepare a product shock absorber 5 for automobile door side collisions (FIGS. 8 and 9). The cell size was measured from the enlarged photograph FIG. 7 and calculated from the magnification, and the average was about 0.8 mm, and the vertical / horizontal ratio of the cell was about 2 on average. ASTM
When the compression characteristic was measured based on D1621-59T, the strain / load characteristic as shown in FIG. 10 was shown.

[0026]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, a shock absorbing foam is formed by cutting out from a hard resin foam that has been foamed in a continuous foaming facility so as to have a vertically long cell structure, with the vertical direction of foaming being the shock absorbing direction. Since it relates to the manufacturing method described above, it is possible to obtain a shock absorber in which the vertical direction of foaming is surely arranged in the shock absorbing direction.

Further, the shock absorber of the present invention, even after being subjected to compression due to a sudden shock or the like, after the lapse of an initial fixed period of time, FIG.
Since a flat compression characteristic as exemplified in (1) is obtained, it is possible to effectively protect the human body from an impact such as a collision. Therefore, compared with conventional molded products, it is possible to obtain far superior impact absorption characteristics and mass production.
Moreover, a product with stable quality can be easily obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing compression characteristics required for a shock absorber.

FIG. 2 is a diagram showing compression characteristics of a molded urethane foam foam.

FIG. 3 is a model diagram in which a cylinder is vertically compressed.

FIG. 4 is a model diagram in which a cylinder is laterally compressed.

FIG. 5 is a model diagram in which an innumerable array of cylinders in a vertical direction is compressed.

FIG. 6 is a diagram showing compression characteristics of a continuous foam product in the lateral direction.

FIG. 7 is an enlarged photograph of a cell of a continuous foam product.

FIG. 8 is a schematic view of a production method by continuous foaming.

FIG. 9 is a schematic view of the continuous foaming of the present method as viewed from above.

FIG. 10 is a diagram showing compression characteristics of a urethane foam produced by this method.

[Explanation of symbols]

 1 Mixing head 2 Conveyor 3 Measuring guide plate 4 Continuous foam molding 5 Impact absorber product

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[Procedure amendment]

[Submission date] November 8, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram showing compression characteristics required for a shock absorber.

FIG. 2 is a diagram showing compression characteristics of a molded urethane foam foam.

FIG. 3 is a model diagram in which a cylinder is vertically compressed.

FIG. 4 is a model diagram in which a cylinder is laterally compressed.

FIG. 5 is a model diagram in which an innumerable array of cylinders in a vertical direction is compressed.

FIG. 6 is a diagram showing compression characteristics of a continuous foam product in the lateral direction.

FIG. 7 is a schematic view of a production method by continuous foaming.

FIG. 8 is a schematic view of the continuous foaming of the present method as viewed from above.

FIG. 9 is a diagram showing compression characteristics of a urethane foam produced by this method.

[Explanation of symbols] 1 Mixing head 2 Conveyor 3 Measuring guide plate 4 Continuous foam molding 5 Impact absorber product

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

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Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area C08G 101: 00) B29K 105: 04 C08L 61:04 75:04

Claims (1)

[Claims] 1. A method for producing a foam by reacting a foam raw material in a continuous foaming facility, wherein a laterally elongated guide plate of the continuous foaming facility is sequentially fitted before the gel time of the foaming reaction to perform foaming to form a vertically long foam cell. A method for producing a shock-absorbing foam, comprising obtaining a hard resin foam having a structure, and cutting and molding the foamed cell so that the longitudinal direction of the foam cells coincides with the shock-absorbing direction.