JP2002234079A - Skin material and method for manufacturing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a skin material with good scratch resistance and chemical resistance and a method for manufacturing the skin material by which the skin material is manufactured by using a thermoplastic polyurethane elastomer with which decrease in environmental loading generated when waste treatment is performed can be expected as a raw material and a specified heating treatment is performed on this skin material. SOLUTION: The skin material is molded by using a crystalline polyurethane elastomer as the raw material and after it is molded, heating treatment is performed at a temperature being lower than the melting temperature of the elastomer by a required temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a skin material and a method for producing the same, and more particularly, to a thermoplastic polyurethane elastomer suitably used for powder slush molding and having high crystallinity and a low melting temperature. Used as a raw material, significantly improving the scratch resistance and chemical resistance by further increasing the crystallinity by performing a predetermined heat treatment, a method of producing a skin material that can be used especially for automobiles,
The present invention relates to a skin material produced by the method. Further, a method of manufacturing a skin material which is mounted and used in an automobile or the like and which is improved in scratch resistance and chemical resistance by being heated by, for example, an in-vehicle environment which is in a high temperature state in summer, and manufactured by the method. Related to the skin material.

[0002]

2. Description of the Related Art For example, vehicle interior materials such as instrument panels are formed by joining a skin material to the surface of a base material such as a resin obtained by injection molding. It is desirable that the skin material has a beautiful appearance, is not easily damaged, and has excellent light resistance, heat resistance, durability, and the like. As a material from which such a skin material can be produced, polyvinyl chloride (hereinafter referred to as PVC) or the like has been suitably used.

However, from the viewpoint of preventing environmental pollution in recent years, acrylonitrile-styrene-acrylate copolymer resins or polyolefin-based elastomers have been replaced with PVC containing a large amount of chlorine, which is one of the sources of dioxin and acid rain. As a material, a skin material obtained by removing a raw material resin from PVC has come to be used.

[0004] As a molding method for processing each of these materials into a skin material, slush molding, which is more excellent in embossing transferability than vacuum molding and can form a high-quality skin material having a high designability, is suitably employed. I have. However, when a skin material is produced by slush molding using the acrylonitrile-styrene-acrylate copolymer resin, moldability is poor,
It is pointed out that a skin material having excellent appearance and the like cannot be formed. The formability referred to here indicates the effect of pinholes associated with air contained on the surface of the skin material when a skin material of a corresponding shape is obtained using a mold having a required shape. If a large number of the pinholes are present on the surface, the appearance is poor and the commercial value is lost. Hereinafter, “formability” described in the present specification is used in the above-mentioned meaning.

[0005]

In view of these points, various production methods, such as slush molding, have been conceived which can suitably produce the above-mentioned skin material using a polyolefin-based elastomer having little problem of environmental pollution as a raw material. . However, the skin material made of the elastomer has a disadvantage that it is easily damaged, that is, the scratch resistance is inferior to the skin material made of PVC as a raw material. In this regard, a composition that can be dealt with by optimizing the blending composition has been studied, but the cost is high and it is not practical.

[0006] As one of means for solving the above-mentioned problems, an invention "a thermoplastic polyurethane elastomer for slush molding, a thermoplastic polyurethane elastomer powder for slush molding, and a skin material using the same" has been devised by the present inventor. (Patent Publication No. 2000-313729
Publication). An object of the present invention is to provide a thermoplastic polyurethane elastomer having specific viscoelastic characteristics or thermal characteristics and suitable for slush molding. As shown in FIG. A thermoplastic polyurethane elastomer having a calorific value represented by the area of the exothermic peak when the calorific value (hereinafter referred to as DSC) is measured of 6 mJ / mg or more and having a temperature T of the exothermic peak of 100 ° C. or more is used as a raw material. It has been found that a skin material having improved scratch resistance, chemical resistance and moldability can be produced by using the same.

However, the above-mentioned invention "the thermoplastic polyurethane elastomer for slush molding, the thermoplastic polyurethane elastomer powder for slush molding, and the skin material using the same" relates to slush molding in the case of having specific viscoelastic properties or thermal properties. The main object of the present invention is to predict the easiness of molding, that is, the quality of the moldability, and to make it possible to easily select the raw material of the skin material. The improvement in the formability is considered to be mainly due to an increase in crystallinity,
As a result, the scratch resistance and the chemical resistance can be improved as compared with the conventional thermoplastic polyurethane elastomer, but it is hardly sufficient when compared with the above-mentioned PVC.

[0008]

SUMMARY OF THE INVENTION The present invention has been proposed to solve the problems inherent in the conventional skin material and the method of manufacturing the same, and has been proposed in order to solve the problems. By subjecting a skin material prepared from a thermoplastic polyurethane elastomer, from which a large reduction in load can be expected, to a predetermined heat treatment, a skin material having good scratch resistance and chemical resistance, and the skin material is manufactured. The purpose is to provide a way to obtain.

[0009]

In order to overcome the above-mentioned problems and achieve the intended object, a skin material having improved scratch resistance and chemical resistance according to the present invention is formed by molding a crystalline polyurethane elastomer as a raw material. And a heat treatment at a temperature lower than the melting temperature of the elastomer by a required temperature after molding.

In order to overcome the above problems and achieve the intended object, a method for producing a skin material according to another invention of the present application is to melt a raw material of a crystalline polyurethane elastomer to form a skin material having a required shape, A heat treatment is performed on the formed skin material at a temperature lower than the melting temperature of the elastomer by a required temperature, thereby improving the scratch resistance and chemical resistance of the skin material.

In order to overcome the above-mentioned problems and achieve the intended object, a method for producing a skin material according to still another invention of the present application is a skin material having a required shape obtained by melting and molding a raw material of a crystalline polyurethane elastomer. By heating the skin material under a natural condition at a temperature lower than the melting temperature of the crystalline polyurethane elastomer by a required temperature, the scratch resistance and chemical resistance of the skin material are improved. It is characterized by.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a skin material and a method for producing the same according to the present invention will be described with reference to preferred embodiments. The inventor of the present application has developed a thermoplastic polyurethane elastomer (hereinafter referred to as T
PU) is used as a raw material, formed into a predetermined shape, and then subjected to a predetermined heat treatment, thereby obtaining a skin material having good scratch resistance and chemical resistance. is there.

A case where the skin material according to the preferred embodiment of the present invention is used for an instrument panel which is a typical interior material of a vehicle will be described with reference to FIGS. 1 and 2. The inside of the instrument panel 10 is secured, and the rigidity of the instrument panel 10 is ensured, and the resin base material 12 molded into a required shape is mounted on the outer surface of the base material 12 for the purpose of improving texture. And a skin material 16. As shown in FIG. 2, a foamed elastic body 14 such as urethane foam having an appropriate elasticity is interposed between the base material 12 and the skin material 16 to improve the tactile sensation.

As shown in FIG. 3, the manufacturing process of the instrument panel 10 basically includes a member preparing step S1, a heating step S2, an integrating step S3 and a finishing step S4. The method includes a base material manufacturing step S11 for manufacturing the base material 12 and a skin material manufacturing step S12 for manufacturing the skin material 16.

The base material preparing step S11 includes a base material 12 capable of providing the instrument panel 10 with sufficient rigidity.
Is produced from an olefin resin material such as polypropylene (PP) by applying a conventionally known molding method such as injection molding.

In the step S12 of preparing the skin material, the skin material 16 used on the surface of the instrument panel 10 is formed.
In general, the shape and size covering the entire outer surface of the base material 12 can be arbitrarily set, and are preferably performed by a powder slush molding method or the like that can easily perform a desired design. You. The powder slush molding die 40 for performing the skin material producing step S12 by the powder slush molding method will be described with reference to FIG. 4. The shell sash includes a molding surface 42 a formed in the shape of the skin material 16 inside a shell 42. , This shell 4
2, a temperature control pipe 44 through which a heat medium for heating and cooling the molding surface 42a flows is disposed.
The bucket 46 in which the powdered TPU powder P is stored can be aligned and mounted in the opening 42b.

Using the powder slush mold 40 constructed as described above, a predetermined amount of plastic TPU powder P is used.
The mold 46 is clamped to the opening 42b, and a heating medium is circulated through the temperature control pipe 44 to heat the molding surface 42a to a predetermined temperature, and the entire mold is rotated at a constant speed ( As shown in FIG. 4 (a), the TPU powder P comes into contact with the molding surface 42a to be gradually heated and gelled, and then adheres with a substantially constant thickness. After a certain time, the bucket 46 is opened to discharge the non-gelled TPU powder P out of the mold, and a cooling medium is circulated through the temperature control pipe 44 to cool the molding surface 42a. Solidify the used TPU. Here, the skin material 16 is obtained from the TPU peeled and removed from the molding surface 42a (see FIG. 4B).

Here, a temperature control pipe 44 is employed as a means for heating the shell 42. However, in addition to the above, the entire shell 42 is immersed in a temperature control tank filled with a heating medium, and the cooling performance is poor. However, a method using an electric heater or the like can also be adopted.

The TPU used in this production step S12 is described in JP-A-2000-3137 from the viewpoint of moldability.
No. 29, that is, the calorific value represented by the area of a calorific peak obtained from a graph of differential scanning calorimetry (DSC) measured in a cooling process after melting is 6 mJ / m.
g or more, and the temperature of the exothermic peak is 100 ° C. or more. ”
TPU is particularly preferred. Any shape may be used as long as it can be sufficiently melted in the production step S12 and has good handleability. For example, it is used in the form of a powder or a granular material.

The TPU will be described specifically.
Basically, it is manufactured by a one-shot method capable of collectively mixing each required raw material, and comprises a polyol component forming a soft segment phase and an isocyanate forming a hard segment phase, for example, adipic acid and 1, 4
TPU produced by condensation of monobutanediol with an adipate-type polyester polyol having hydroxyl groups at both terminals and hexamethylene diisocyanate (HDI) as a short-chain diisocyanate (urethane-forming reaction). . In addition to the above-described one-shot method, it can also be manufactured by a conventionally known prepolymer method.

Japanese Patent Application Laid-Open No. 2000-313729 describes that those having the following conditions have high crystallinity, and consequently exhibit good moldability.
Its molecular structure is easy to arrange linearly. The number of urethane bonds per molecule is large, and the bonding force due to hydrogen bonding is greatly expressed. Does not have an excessive crosslinked structure in the structure.

TPU that satisfies the above conditions
Is produced by reacting an isocyanate, which is a main raw material, with a polyol. In this case, 100 to 100 mol of a chain extender such as a short-chain diol and about 1 to 5 moles of the polyol are used. About 500 ppm of a urethane polymerization catalyst is added. The polyol and isocyanate used may have not only two functional groups but also three or more functional groups.

The equivalent ratio (NCO / OH ratio) of the isocyanate group (NCO group) in the structure of the isocyanate to the hydroxyl group (OH group) of the polyol contained in the polyol component is 0.95 to 1 .05 is preferable. If the NCO / OH ratio is less than 0.95, the moldability during slush molding will be improved, but the resulting molded article will have reduced chemical resistance and the like. On the other hand, this ratio is 1.0
If it exceeds 5, the degree of cross-linking of the TPU due to allophanate bonds or burette bonds becomes too high, and the moldability decreases. Even if the NCO / OH ratio is large, if the blending amount of the polymerization catalyst is large, the
O groups are consumed, NCO groups that do not contribute to urethanization increase, the molecular weight does not increase, and a decrease in moldability may be suppressed.

As the isocyanate, the above-mentioned HD
I, diphenylmethane diisocyanate (MDI),
Hydrogenated MDI or isophorone diisocyanate can also be used, and the type is not limited. HDI, MDI and / or hydrogenated MD, especially those having a symmetric molecular structure
I and the like are preferred. When an isocyanate-terminated prepolymer having isocyanates at both ends is used, it is possible to increase the hydrogen bonding force of the hard segment phase and to enhance the crystallinity.

Examples of the polyol include condensation-polymerized polyester polyols, polyester polyols obtained by ring-opening polymerization of cyclic esters such as ε-caprolactone, polyether polyols obtained by ring-opening polymerization of cyclic ethers, and copolymers thereof. A polyetherester polyol or the like obtained by polymerization can be used. Further, a polymer polyol such as a polycarbonate polyol having a carbonate group can also be used. Further, a monomer polyol such as 1,4-butanediol may be used in combination with each of these polyols.

The number average molecular weight of the polyol is as follows:
Those having a size of about 500 to 10,000 are used.
The range of from 00 to 3,000 is preferred. If the number average molecular weight is too large, the soft segment phase relatively increases and the crystallinity decreases, so that excellent moldability cannot be maintained. On the other hand, if the number average molecular weight is too small, the hard segment phase increases and the finished TPU becomes hard. Therefore, when it is used for a skin material as in the present invention, attention must be paid to the sense of touch and the like.

When the above-mentioned monomer polyol is used in combination,
Partial hard segment phase growth occurs in the molecular chain,
Crystallinity further increases. At this time, if the amount of the monomer polyol used is large, it is necessary to pay attention to the fact that the elastomer becomes harder as the crystallization proceeds. On the other hand, in particular, the polyester polyol is hydrogen-bonded to a urethane bond, and the soft segment phase becomes longer and the hard segment phase becomes relatively shorter, so that the crystallinity may be lowered. Thus TP
Many factors affect the quantitative ratio between the hard segment phase and the soft segment phase of U.

Furthermore, trifunctional or higher functional isocyanates and / or
And the use of a polyol, it is possible to reduce the crystallinity or to suppress the decrease in viscosity during molding. It is necessary to suppress the amount to 5 mol% or less. In addition, for other additives and the like, in order to obtain a TPU having desired characteristics, it is necessary to study the action and effect of the raw material composition and the like.

The TPU raw material may contain various additives and the like in addition to the isocyanate and polyol as main raw materials. These are blended into the polyol in advance,
It is often mixed with an isocyanate as a polyol component. Examples of such additives include liquid plasticizers such as phthalic acid esters and trimellitic acid esters, which have the effect of lowering the melt viscosity of the elastomer raw material during molding. The mixing amount of these plasticizers is preferably 20 parts or less, particularly preferably 15 parts or less based on 100 parts by mass of the raw material (hereinafter simply referred to as “parts”). If the amount is more than 20 parts, the plasticizer may bleed out on the surface of the obtained skin material comprising the elastomer, which is not preferable.

Further, in order to increase the rigidity of the TPU or to improve the pulverizability when pulverized by freeze-pulverization or the like, an inorganic filler such as talc, calcium carbonate, silica or the like may be added to the TPU raw material. Thereby, the yield at the time of powdering can be improved. The compounding amount of these inorganic fillers is preferably 40 parts or less, particularly preferably 30 parts or less based on 100 parts of the raw material. When the amount is more than 40 parts, the moldability of the obtained TPU decreases,
The feeling is inferior and the surface of the skin material may be too hard, which is not preferable.

The molding method employed in the skin material producing step S12 includes, in addition to the powder slush molding method described above, which is capable of forming a high-grade skin material having excellent grain transferability and high designability, and a vacuum method. A molding method or the like can also be adopted.

The heat treatment step S2 to be performed next is a step of forming the skin material 1 formed into a required shape in the skin material manufacturing step S12.
6 is a step of performing a predetermined heat treatment using, for example, a circulating hot air heating device or the like.

By performing this heat treatment step S2,
The degree of crystallinity of the skin material 16 is increased. FIGS. 5 and 6 show the results of measuring the differential scanning calorific value (hereinafter, referred to as DSC) in the process of heating the skin material 16 before the main heat treatment step S2 and the skin material 16 after the main heat treatment step S2. In this case, the heat treatment step S2 is performed at a temperature of 110
C., 24 hours. 5 and 6
The equipment used in performing the measurement described above is as follows.・ Thermal property device: Model SSC5200; manufactured by Seiko Electronics Co., Ltd. ・ For heat absorption, see JIS K
7121, 7122 and 7123 (Japanese Standards Association 19
97th edition "JIS Handbook 11 446 pages-455"
Page ").

Referring to FIG. 6 with reference to FIG. 5, an endothermic peak showing crystallinity is shown as 11.5 mg to 1 mg.
It is confirmed that the amount is increased to 8.3 mg. The endothermic amount was calculated to be about 1.6 times that before implementation, and an increase in crystallinity was clearly recognized by the heat treatment. Although not shown, the temperature is 110 ° C., 500 hours, and 1,000 hours.
When heat treatment was performed for a long time, it was confirmed that the endothermic amount indicating the crystallinity reached a plateau of about twice in each case. This increase in crystallinity is inferred as follows.

In the case of the one-shot method in which the four components of the basic materials, polymer polyol, isocyanate, chain extender and catalyst, are mixed together, both the polymer polyol having an OH group at its terminal and the chain extender are Reacts with. The reaction rate at this time largely depends on the respective molecular weights, that is, the diffusion rate, and the chain extender having a smaller molecular weight reacts with the isocyanate with a higher probability.
(Polymerization) to form the hard segment phase. And the polymer polyol and the isocyanate react with a lower probability than that of the chain extender, that is, with a delay (polymerization).
To form the soft segment phase.

In general, the hard segment phase and the soft segment phase are not completely compatible with each other, and the hard segment phase and the soft segment phase are separated by cooling and solidification after the reaction, and the hard segment phase has crystallinity. It is expressed. This model is an ester-based polymer polyol having an ester group formed by condensation polymerization of dicarponic acid and a diol component, or an ether-based polymer polyol having an ether group formed by ring-opening polymerization of a cyclic ether such as ethylene oxide. This is apparent from the fact that the soft segment phase has the ester group or the ether group, respectively, whereas the hard segment phase does not have the same functional group, and therefore has poor chemical affinity and is hardly compatible. From these facts, it can be said that the portion exhibiting crystallinity in the TPU manufactured by the ordinary one-shot method is a portion of the hard segment phase.

However, considering that the one-shot method performs batch mixing of raw materials, the isocyanate and
It is unlikely that the chain extender or the polymer polyol alone completes the polymerization alone. That is, when a part of the polymer polyol is simultaneously involved during the polymerization of the hard segment phase in which the reaction proceeds predominantly, it is considered that the polymerization reaction of the polymer polyol is performed together with the polymerization reaction of the chain extender to form a copolymer. Can be Despite having a hard segment phase, the copolymer synthesized in this way does not show as high a crystallinity as a single hard segment phase.

Therefore, it is inferred that the TPU manufactured and cooled and solidified by the one-shot method takes a structural model as shown in FIG. 7 as a concept. This structural model shows a state in which mutually incompatible ones are dispersed without receiving an external pressure. In this case, any one of the hard segment phase and the soft segment phase constituting the TPU (FIG. 7) In this case, it is considered that the hard segment phase has a sea-island structure in which the hard segment phase exists as an island having a minimum interface area. That is, the structure is composed of a hard segment phase 12 exhibiting crystallinity, a non-crystalline soft segment phase 14 and a copolymer 16 having relatively low crystallinity (see FIG. 7A). Here, the copolymer 16 includes a copolymer 16a mixed in the soft segment phase 14,
Copolymer 16b mixed around the periphery of the island
And two types. The copolymer 16a is obtained by incorporating a small amount of a polymer polyol into the hard segment phase 12, while the copolymer 16b cannot participate in crystal growth upon cooling and solidification, and the soft segment phase 1
4 is left behind.

When heat is applied to the TPU having such a structure, the copolymer 16b exhibits a behavior of separating from the soft segment phase 14 due to the cohesive energy of the hard segment phase 12 and leading to crystal growth. That is, the copolymer 16b grows so as to further surround the copolymer 16a to form the second hard segment phase 18 and the second hard segment phase 18 which is newly independent in the soft segment phase 14.
, And apparently behaves as if the hard segment phases 12 (islands) exhibiting crystallinity increased (see FIG. 7 (b)).

When the second hard segment phase 18 having new crystallinity is formed, the DSC data in the process of heating the TPU having the second hard segment phase 18 are measured. Hard segment phase 18
, An endothermic peak on the low temperature side appears. Then D
As can be seen from the endothermic amount obtained from the SC data, the region having crystallinity, that is, the crystallinity is quantitatively increased, and as a result, the scratch resistance and chemical resistance expressed by the crystallinity are improved. However, no matter how long it takes, the crystallinity does not increase after reaching a certain value, since the formation of the second hard segment phase 18 above the copolymer 16 present in quantity is not possible. That is, there is an upper limit to the time for performing the heat treatment step S2 for efficient crystallization.

The temperature for the heat treatment is preferably lower than the temperature of the endothermic peak which is increased by the heat treatment and as high as possible in a temperature range lower than the melting temperature of the TPU to be subjected to the heat treatment. If the temperature of this heat treatment is low, it takes time to form the second hard segment phase that develops an endothermic peak. The time for performing the heat treatment depends on the temperature for performing the heat treatment,
Empirically, good results can be obtained by performing the treatment continuously for 6 hours or more. If the time is shorter than this, care must be taken because sufficient scratch resistance and chemical resistance cannot be obtained.

In the subsequent integration step S3, the base material 12 manufactured up to the previous step S2 and the skin material 16 manufactured and subjected to the heat treatment are integrated via the foamed elastic body 14. This is a step, for example, performed using a manufacturing apparatus 50 shown in FIG. The manufacturing apparatus 50 includes the skin material 1
6 and the base 12 are mounted in accordance with their shapes, respectively, and the lower mold 5 capable of sealing and defining a molding space 58 therein.
2 and an upper mold 54; an injection nozzle 56 for injecting the raw material of the foamed elastic body 14 between the skin material 16 and the base material 12;
And a moving device (not shown) that can move the device so that it can approach and seal. First, the skin material 16 and the base material 12 are attached to the lower mold 52 and the upper mold 54, respectively. And the skin material 16
The raw material of the foamed elastic body 14 is injected between the base material 12 and the injection nozzle 56 (see FIG. 8A),
And the upper mold 54 is sealed to foam the raw material (FIG. 8).
(b)). Then, the instrument panel 10 in which the skin material 16 and the base material 12 are joined via the foamed elastic body 14 is obtained by foaming and curing of the raw material. Finally, the lower mold 52 and the upper mold 54 are separated from each other, and the instrument panel 10 may be removed from the instrument panel 10 (FIG. 8).
(See (c)).

By going through the steps S1, S2 and S3 up to this point, it is possible to obtain the instrument panel 10 having the skin material 16 with greatly improved scratch resistance and chemical resistance. The final finishing step S4 is
This is a step of subjecting the instrument panel 10 to a final finish, a predetermined inspection, and the like to obtain a final product.

In this embodiment, the produced skin material 16 is subjected to a heat treatment as a manufacturing process to improve the scratch resistance and the chemical resistance. It is heated by the environment inside the car, which is hot in summer due to being installed and used in the car. Heating under these use conditions is not sufficient compared to the above-mentioned heat treatment step S2, but this also improves the scratch resistance and chemical resistance.

In this embodiment, the vehicle interior material is described using an instrument panel. However, the vehicle interior material is not limited to this, and a door trim (lining member) installed inside a side door is used. Vehicle interior materials to which the skin material of each vehicle interior material such as a pillar garnish installed in the pillar portion is attached are all covered.

[0046]

EXPERIMENTAL EXAMPLES Preferred experimental examples of the skin material produced by the method for producing a skin material according to the present invention are shown below, but the skin material according to the present invention and the method for producing the same are limited to these experimental examples. Not something.

(Experimental conditions) Using a predetermined TPU as a raw material, molding into a required shape by powder slush molding,
Each skin material was obtained by performing a heat treatment under various conditions. And the chemical resistance of each obtained skin material was confirmed. Chemical resistance is ethanol dropped on the surface of the skin material, temperature 110 ° C.,
After being left for 48 hours, the skin condition at the dropping position was visually checked for evaluation. Those subjected to the heat treatment described in the present application are described as Experiments 1 to 4, and the others are described as Comparative 1 and Comparative 2. Table 1 below shows the heat treatment conditions and the chemical resistance evaluation results for each TPU. -Materials used: General-purpose TPU (trade name: E785QSDH; manufactured by Nippon Milactran)

[0048]

[Table 1]

(Results) The chemical resistance ascertained from the surface condition of the skin material was as follows: X: Traces were clearly left and there was no merchantability, Δ: Some traces remained, low commercial value, ○:
No problem was evaluated. The evaluation contents are also shown in Table 1 above. As a result, it was confirmed that heat treatment was required at a temperature of 110 ° C. for at least 6 hours, and good results were obtained within the range described in the present invention.

[0050]

As described above, according to the skin material and the method for producing the same according to the present invention, a skin material having high scratch resistance and chemical resistance can be easily obtained by performing a predetermined heat treatment. be able to. Further, for example, even when the vehicle is exposed outdoors in summer, and is exposed to high temperatures, the skin material is heated, so that scratch resistance and chemical resistance are improved. This makes it possible to produce a skin material from thermoplastic polyurethane elastomer, which eliminates the burden on the environment, which has been a concern with the use of PVC, and which has scratch resistance and chemical resistance equal to or higher than that of PVC.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an instrument panel equipped with a skin material according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a structure of an instrument panel to which a skin material according to the embodiment is mounted.

FIG. 3 is a flowchart illustrating a manufacturing process of the instrument panel according to the embodiment.

FIG. 4 is a process diagram showing step by step a powder slush molding method suitably adopted in a skin material producing step S12.

FIG. 5 shows a process D of heating the skin material before the heat treatment.
It is a graph which shows SC data.

FIG. 6 is a graph showing DSC data in a process of heating a skin material subjected to a heat treatment at a temperature of 110 ° C. for 24 hours.

FIG. 7 is a schematic diagram showing a structural model before and after a heat treatment of a skin material according to an example.

FIG. 8 is a process chart showing stepwise an injection molding method suitably adopted in the integration step S3.

FIG. 9 is a graph showing D when the temperature of a thermoplastic polyurethane elastomer, which is a raw material of a skin material according to the prior art, was raised to 250 ° C. and completely melted, and then lowered at a rate of 10 ° C./min.
It is a graph which shows SC data.

[Explanation of symbols]

 16 Skin material T Temperature of exothermic peak

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D044 BA11 BB01 BC04 4F201 AA31 AA45 AH26 AR06 AR11 BA07 BC01 BC02 BC12 BC15 BR13 4F205 AA31 AC04 AH25 AH26 AM27 GA12 GB01 GC04 GW06

Claims (9)

[Claims] 1. A molded article made of a crystalline polyurethane elastomer, which has been subjected to a heat treatment at a temperature lower than a melting temperature of the elastomer by a required temperature after the molding, and has a scratch-resistant property. Skin material with improved chemical resistance. 2. The crystalline polyurethane elastomer,
Differential scanning calorimetry (DS) measured during the cooling process after melting
The calorific value represented by the area of the exothermic peak obtained from the graph of C) is 6 mJ / mg or more, and the temperature of the exothermic peak (T)
The skin material according to claim 1, wherein the temperature is 100 ° C or higher. 3. The skin material according to claim 1, wherein the molded product is manufactured by powder slush molding. 4. A raw material of a crystalline polyurethane elastomer is melted to form a skin material (16) having a required shape, and the formed skin material (16) is heated by a temperature lower than a melting temperature of the elastomer by a required temperature. A method for producing a skin material, characterized by improving the scratch resistance and chemical resistance of the skin material (16) by performing a treatment. 5. The crystalline polyurethane elastomer,
Differential scanning calorimetry (DS) measured during the cooling process after melting
The calorific value represented by the area of the exothermic peak obtained from the graph of C) is 6 mJ / mg or more, and the temperature of the exothermic peak (T)
The method for producing a skin material according to claim 4, wherein the temperature is 100 ° C or higher. 6. The method for producing a skin material according to claim 4, wherein the heat treatment is performed in a temperature range of −50 ° C. to −20 ° C. from a melting temperature of the crystalline polyurethane elastomer. 7. The method for producing a skin material according to claim 4, wherein the heat treatment is performed continuously for at least 6 hours. 8. The method for producing a skin material according to claim 4, wherein the molding of the skin material (16) is performed by powder slush molding. 9. A skin material (16) having a required shape formed by melting and molding a raw material of a crystalline polyurethane elastomer, wherein the skin material (16) has a required temperature higher than a melting temperature of the crystalline polyurethane elastomer under use conditions. A method for producing a skin material, characterized in that the skin material (16) is improved in scratch resistance and chemical resistance by being heated at a temperature just below the temperature.